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  • 1
    ISSN: 1432-2277
    Keywords: Key words Liver transplantation ; Posttransplant lymphoproliferative disease ; Epstein-Barr virus ; Humans ; Children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Epstein-Barr virus (EBV) infection can induce uncontrolled lymphocyte B proliferation in immunosuppressed transplant patients. Monitoring circulating EBV-infected lymphocytes can help in identifying patients at risk of posttransplant lymphoproliferative disease (PTLD). Circulating EBV genome levels were determined in 54 liver transplant pediatric recipients. Ten patients had more than 500 EBV genome/105 peripheral blood lymphocytes (PBL) and exhibited clinical manifestations of EBV infection; three developed PTLD. To treat EBV infection, the level of immunosuppression was reduced and acute rejection developed in 4 patients. Three were treated with steroid and one had to be switched from cyclosporine to tacrolimus. Treatment of acute rejection was associated with increases in circulating EBV genome. None of the patients with less than 500 EBV genome/105 PBL developed PTLD or EBV infection. Monitoring of EBV DNA is useful in the management of EBV infection and PTLD following pediatric liver transplantation. EBV infection should be treated in ways which do not expose patients to the risk of rejection.
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  • 2
    ISSN: 1432-2161
    Keywords: Key words Bone mineral density ; Dual energy X-ray absorptiometry ; Children ; Rickets ; X-linked hypophosphatemia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Objective. To evaluate the bone mineral status of children being treated for X-linked hypophosphatemia, including potential differences between cortical bone in the radial diaphysis and combined cortical and trabecular bone in the lumbar spine. Design and patients. Forty-four bone mineral evaluations were performed in 11 children and adolescents with X-linked hypophosphatemia. Bone mineral density (BMD) of the lumbar spine and the radial diaphysis were measured by dual X-ray absorptiometry (DXA), second metacarpal cortical thickness was measured on hand radiographs, and these results were expressed as Z-scores (standard deviations from the mean). Results. For the 11 initial examinations, Z-scores (mean±SD) were: radial BMD, –2.73±1.15, lumbar BMD, +1.28±1.53; and cortical thickness, –2.21±0.95. Lumbar BMD Z-scores were significantly greater than those for radial BMD and cortical thickness. On follow-up examinations there was a mild increase in radial BMD and decrease in lumbar BMD. Although these changes were statistically significant, they were quite small and the discordance between radial and lumbar BMD was not corrected. Conclusions. Children and adolescents who are being treated for X-linked hypophosphatemia manifest a bone mineral disorder characterized by decreased BMD in the appendicular skeleton and increased BMD in the lumbar spine. Although current therapy is successful in its anti-rachitic effects, it does not correct this bone mineral disorder and additional therapeutic trials should be considered.
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  • 3
    ISSN: 1432-2129
    Keywords: Schlüsselwörter ; Kopfschmerz ; Kinder ; Akuttherapie ; Flupirtin ; Paracetamol ; Keywords ; Children ; Acute treatment ; Tension-type headache ; Flupirtine ; Paracetamol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Background: About 10% of all schoolchil- dren are suffering from migraine and 50% from tension-type headache. Headache of acute onset usually will be treated with analgesic substances like paracetamol, acetylsalicylic acid or ibuprofen, the first one being the reference drug for tension-type headache in childhood. In case of lacking improvement or side-effects there is demand for an alternative safe substance for the acute analgesic therapy. Methods: In a double-blind randomised investigation flupirtine and paracetamol were given in two consecutive attacks of episodic tension-type headache. 30 children, 6–12 years old, were included. Dosage was determined according to age and weight. The children documented the acute headache intensity and duration in a special diary. Results: Headache intensity was reduced during 2 h after intake in 89% of the 19 children treated. The reduction was 6,5 to 3,1 for flupirtine and 6,9 to 3,3/10 for paracetamol. There was no statistically significant difference between the two substances. Relevant side-effects could not be observed. Conclusion: Flupirtine has shown a convincing clinical effect treating acute episodic tension-type headache for children. The substance was well tolerated by the patients. In addition, flupirtine provides a high degree of safety.
    Notes: Zusammenfassung Hintergrund: Etwa 10% aller Schulkinder leiden nach neueren deutschen epidemiologischen Untersuchungen zumindest gelegentlich an Migräne und etwa 50% an Kopfschmerzen vom Spannungstyp. Häufig nehmen sie bei Spannungskopfschmerzen analgetische Monosubstanzen wie Paracetamol, Azetylsalizylsäure oder Ibuprofen ein. Bei nicht ausreichender Wirkung bzw. Unverträglichkeit besteht Bedarf nach weiteren Substanzen für die Akutanwendung. Methode: In einer doppelblindrandomisierten und gekreuzten Anordnung wurden Paracetamol bzw. das analgetisch und muskelrelaxierend wirksame Flupirtin 30 6- bis 12jährigen Kindern für 2 episodische Spannungskopfschmerzattacken angeboten. 10 Kinder benötigten nach dem Erstkontakt keine Medikation mehr, 1 Kind lehnte die Einnahme grundsätzlich ab. Ergebnisse: Die Kopfschmerzstärke verringerte sich laut Kopfschmerztagebuch innerhalb von 2 h nach der Einnahme auf einer numerischen Schmerzskala (0–10) von 6,5 auf 3,1 unter Flupirtin und von 6,9 auf 3,3 unter Paracetamol bei 89% der verbliebenen 19 Kinder. Statistisch signifikante Unterschiede zwischen beiden Substanzen bestanden nicht. Als Nebenwirkung trat 1-mal Erbrechen unter Paracetamol auf. Schlussfolgerung: Flupirtin hat sich in der Akutphase von episodischen Spannungskopfschmerzen beim Kind bewährt. Es verfügt über eine gute Verträglichkeit. Im Vergleich zu Paracetamol scheint v.a. bei akzidenteller Überdosierung eine größere Sicherheit zu bestehen.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Der Schmerz 14 (2000), S. 302-308 
    ISSN: 1432-2129
    Keywords: Schlüsselwörter Schmerzmessung ; Diagnostik ; Instrumente ; Neugeborene ; Kinder ; Keywords Pain ; Measurement ; Assessment ; Instruments ; Neonates ; Children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Background. The assessment and measurement of pain is essential in the implementation and control of pain relieving strategies. The measurement of pain in infants and children should be based on the consideration of age, cognitive level, psychological status, intercurrent diseases and the social context in order to register the child's individual situation and to avoid misinterpretation. Diagnosis. In the preverbal infant, behavioral and physiological cues have to be interpreted by the caregivers. For the assessment of pain in children of four and older who have at least a basic understanding of the pain concept self assessment methods (as rating scales, specific pain interviews, diaries and questionnaires) can be used. In any case the instruments used should be age appropriate. The instruments used for the different age groups are presented with comments on quality and clinical applicability.
    Notes: Zusammenfassung Hintergrund. Voraussetzung zur Durchführung und Kontrolle einer adäquaten und effektiven Schmerztherapie sind die Erfassung und Quantifizierung des Schmerzes in seinen verschiedenen Dimensionen. Bei der Diagnostik des Schmerzes im Kindesalter müssen Alter, kognitiver Entwicklungsstand, psychologischer Status, interkurrierende Erkrankungen und der soziale Kontext berücksichtigt werden, um das Kind in seiner individuellen Situation erfassen zu können und Fehleinschätzungen zu vermeiden. Schmerzdiagnostik im Kindesalter. Im präverbalen Alter werden die physiologischen und verhaltensbezogenen Schmerzäußerungen von Neugeborenen, Säuglingen und Kleinkindern durch eine Fremdbeurteilung erfasst. Bei Kindern ab etwa 4 Jahren, die über ein einfaches Verständnis von Schmerz verfügen, sind Verfahren der Selbsteinschätzung wie einfache Ratingskalen, spezifische Schmerzinterviews, Tagebücher und Fragebögen die primär einzusetzenden Instrumente. In jedem Fall sollten die Instrumente altersgerecht gestaltet sein. Für die verschiedenen Altersgruppen werden Instrumente der Schmerzerfassung mit qualitativen Hinweisen auf deren Güte und klinische Anwendbarkeit vorgestellt.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Der Schmerz 14 (2000), S. 319-323 
    ISSN: 1432-2129
    Keywords: Schlüsselwörter Schmerz ; Kinder ; Impfung ; Verbrennung ; Injektion ; Keywords Pain ; Children ; Vaccination ; Burn ; Injection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Phenomenon pain. While pain is one of the main reasons for an unscheduled visit to the paediatrician, pain due to painful procedures is of major importance in scheduled visits. Actual pain therapy is illustrated in the treatment of burns. Incomplete analgesia may have an unfavourable impact on morbidity and mortality. The pain score does not correlate with the extent of the burned area, and is regularly underestimated. General anaesthesia or analgo-sedation are warranted during the care of the burned patient. Unsufficient analgesia. Consequence of insufficient analgesia during primary care is an increased need of analgesics, and an increased pain treatment failure rate during subsequent procedures. Pain is interfering with anxiety, sleep disturbancies and post-tramatic psychologic alterations. All those symptoms must be treated adequately. Acute illness and injections. This article covers pain from otitis media, pharyngitis, Guillain-Barré syndrome, purpura fulminans, Toxic Epidermal Nekrolysis, as well as the usage of local anaesthesia during injections, not to forget the application of non-pharmacologic methods for pain therapy and prophylaxis.
    Notes: Zusammenfassung Phänomen Schmerz. Das Phänomen “Schmerz” begleitet fast alltäglich den Kontakt zwischen Arzt und krankem Kind. Auf der einen Seite sind Schmerzen der häufigste Grund für eine ungeplante Kinderarztkonsultation, auf der anderen Seite sind bei geplanten Kinderarztbesuchen häufig schmerzhafte Prozeduren durchzuführen. Anhand der starken Schmerzen bei den im Kleinkindalter häufigen Verbrennungen werden schmerztherapeutische Prinzipien konkretisiert: Schmerztherapeutische Prinzipien. Unzureichende Analgesie kann Morbidität und Mortalität ungünstig beeinflussen. Das Schmerzmaß korreliert nicht mit der Ausdehnung der Verbrennung und wird vom Behandler regelmäßig unterschätzt. In vielen Fällen der Erstversorgung sind Allgemeinanästhesie oder Analgosedierung gerechtfertigt, ähnliches gilt für den Verbandwechsel. Ungenügende Analgesie bei der Erstversorgung führt zu erhöhtem Analgetikaverbrauch und schmerztherapeutischen Misserfolgen bei Folgeeingriffen. Wechselwirkungen zwischen Schmerzen und anderen Symptomen wie Angst, Schlafstörungen oder postraumatischen psychischen Veränderungen sind zu beachten und adäquat zu therapieren. Akute Erkrankungen + Injektionen. Weiter wird auf Schmerzen bei Otitis media, Pharyngitis, Guillain-Barré-Syndrom, Purpura Fulminans und Toxischer Epidermaler Nekrolyse sowie den Einsatz von Lokalanästhetika bei Injektionen eingegangen. Schließlich haben auch nicht pharmakologische Methoden ihren Platz in Schmerztherapie und Prophylaxe.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Der Schmerz 14 (2000), S. 333-339 
    ISSN: 1432-2129
    Keywords: Schlüsselwörter Postoperative Schmerztherapie ; Schmerz ; Kinder ; Jugendliche ; Analgetika ; Keywords Postoperative pain therapy ; Pain ; Children ; Adolescents ; Analgesics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Treatment of pain. Undertreatment of postoperative pain in children is a problem in clinical practice. This is due to a lack of both knowledge about age-specific aspects of physiology and pharmacology, and routine pain assessment. For example, the fear of side-effects prevents the adequate usage of opioids. It is of major importance to select a route of drug administration where the child feels comfortable with (avoid intramuscular injections). Non-opioid analgesics. Non-opioid analgesics are recommended for basic pain treatment after minor surgical procedures. Instead of using the whole multitude of drugs available, the doctor should stick to those drugs he is familiar with (acetaminophen, ibuprofen, diclofenac, dipyrone). Opioids. Opioid usage requires individual dose titration and careful monitoring of side-effects (respiratory monitoring, sedation score). The strong opioids piritramide and morphine may advantageously be administered as either continuous, or patient-controlled iv- infusion (PCA). Forms of therapy. In addition to infiltration anesthesia, intraoperatively applied nerve blocks provide excellent pain relief. Epidural analgesia with local anesthetics and/or opioids via a thoracic or lumbar epidural catheter is a therapeutic option after thoracic or abdominal surgery, or after extensive orthopedic or urological interventions. Adjuvant analgesics and nonpharmacologic interventions, i. e. transcutaneous electrical nerve stimulation (TENS), are primarily indicated in patients suffering from neuropathic pain. Conclusion. The establishment of pain services and the comprehensive education of both the nursing and the medical staff should help to improve postoperative pediatric pain therapy.
    Notes: Zusammenfassung Schmerztherapie bei Kindern. Postoperative Schmerzen bei Kindern werden häufig wegen mangelnder physiologischer und pharmakologischer Kenntnisse und des Fehlens einer regelmäßigen standardisierten Schmerzmessung noch immer unzureichend behandelt. Die Angst vor Nebenwirkungen verhindert eine adäquate Opioidtherapie. Bei der Verwendung von Analgetika ist auf eine kindgerechte Applikationsweise (keine i.-m.-Injektionen!) zu achten. Nichtopioidhaltige Analgetika. Nichtopioidhaltige Analgetika (Parazetamol, Ibuprofen, Diclofenac, Metamizol) sind zur Basisschmerztherapie bei kleineren schmerzhaften Eingriffen geeignet. Opioide. Opioide müssen nach Wirkung titriert werden; Nebenwirkungen können nur bei sorgfältigem Monitoring von Atmung und Sedierungsgrad frühzeitig erkannt werden. Opioide (Tramadol, Piritramid, Morphin) können entweder kontinuierlich i. v. oder mittels PCA-Pumpe verabreicht werden. Therapieformen. Neben der Oberflächenanästhesie sind intraoperativ angelegte Nervenblockaden effektive therapeutische Möglichkeiten. Eine lumbale und thorakale Periduralanästhesie mittels Lokalanästhetika und/oder Opioiden bietet sich bei thorakoabdominalen Eingriffen an. Koanalgetika werden vornehmlich bei Nervenschmerzen verwendet und richten sich gegen die schmerzverursachende Pathophysiologie. Optimierung der Schmerztherapie. Die postoperative Schmerztherapie bei Kindern kann durch Einrichtung eines Akutschmerzdiensts und kontinuierliche Weiterbildung von Pflegepersonal und Ärzten optimiert werden.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Pediatric nephrology 14 (2000), S. 1016-1021 
    ISSN: 1432-198X
    Keywords: Key words Nephrocalcinosis ; Sonography ; Renal function ; Body growth ; Children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  We carried out a retrospective survey on 152 children and adolescents with nephrocalcinosis (NC) in 22 German centers of pediatric nephrology. Etiology, clinical manifestations, growth and development, sonographic appearance of NC and renal function were analyzed. The median age at the time of diagnosis was 3.3 (range 0.1–21) years and the median duration of follow-up was 4.1 years. In 34% of children NC was associated with idiopathic hypercalciuria (IHC) and in 32% with various hereditary tubular disorders. In 9% NC was observed subsequent to prophylactic bolus administration of vitamin D in infancy. A positive family history was found in 36%. Clinical manifestations were mainly failure to thrive during the 1st year of life (46%), psychomotor/mental retardation (28%) and urinary tract infection (34%). In 14% nephrolithiasis was associated. During the follow-up the proportion of patients with the most severe degree of NC (stages 2b or 3) increased from 40% to 55% and that of hypercalciuria decreased from 79% to 52%. Body height was 〈2 standard deviation scores (SDS) of normal in 41% at the time of diagnosis and in 32% at the last observation; the increase in relative height was significant only for IHC. Glomerular filtration rate (GFR) and urinary concentration capacity changed only slightly with time. At the last investigation GFR was 〈50 ml/min/1.73 m2 in 6% and concentration capacity 〈800 mosmol/kg in 48% of patients. The degree of NC was negatively correlated with GFR and concentration capacity.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Pediatric nephrology 15 (2000), S. 302-316 
    ISSN: 1432-198X
    Keywords: Key words Calcium channel blockers ; Children ; Pharmacokinetics ; Hypertension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The calcium channel blockers (CCBs) are a diverse group of antihypertensive medications with variable pharmacokinetics and clinical effects. Although CCBs have been widely applied to the treatment of hypertensive children, data regarding the pharmacokinetics, efficacy and safety of these agents in children are extremely limited. In this review we briefly summarize the mechanism of action of CCBs and then summarize pertinent pharmacokinetic information on each of the CCBs commonly used in children, including amlodipine, diltiazem, felodipine, isradipine, intravenous nicardipine, nifedipine and verapamil. Clinically important drug interactions and adverse effects are discussed, as well as the potential role of CCBs in renal protection. Available pediatric efficacy and safety data are summarized, and recommendations made regarding the rational use of CCBs in the management of pediatric hypertension.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Pediatric nephrology 15 (2000), S. 57-59 
    ISSN: 1432-198X
    Keywords: Keywords X-linked hypophosphatemia ; Dipyridamole ; Children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  X-linked hypophosphatemia (XLH) is characterized clinically by rickets, hypophosphatemia and hyperphosphaturia. Conventional treatment of XLH with oral phosphate and vitamin D is associated with hypercalcuria and nephrocalcinosis. Recently, intravenous and oral dipyridamole has been reported to decrease fractional excretion of phosphate in adults with idiopathic hyperphosphaturia. Our objective was to determine whether oral dipyridamole therapy reduces urinary phosphate excretion and increases serum phosphate concentration in children with XLH. A prospective study was performed in six children with XLH. The average age of the patients at the start of the study was 12.5±1.0 years. The effects of 12 weeks of oral dipyridamole therapy, at 4.4±0.4 mg/kg body weight per day, on serum phosphorous, parathyroid hormone (PTH), 1,25 (OH)2 vitamin D, osteocalcin, tubular maximum for phosphate reabsorption (TmP/GFR), urinary calcium excretion, and cyclic adenosine 3’,5’-monophosphate (cAMP) excretion, were compared to baseline levels. Our results show that there was no change in serum phosphorous concentration or TmP/GFR after 12 weeks of dipyridamole therapy. Dipyridamole therapy also had no effect on serum PTH, serum 1,25 (OH)2 vitamin D, alkaline phosphatase, osteocalcin levels, urinary calcium or cAMP excretion. We therefore concluded that in children with XLH, a 12-week course of dipyridamole had no effect on serum phosphorous or its urinary excretion. Dipyridamole therapy is unlikely to improve the bone disease in children with XLH.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Pediatric nephrology 15 (2000), S. 248-251 
    ISSN: 1432-198X
    Keywords: Key words Nephrotic syndrome ; Acute renal failure ; Children ; Peritonitis ; Ischemic tubular necrosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Idiopathic acute renal failure (IARF) is an uncommon but severe complication in children with relapsing nephrotic syndrome and may require long-term dialytic support until recovery of renal function takes place. Due to limited understanding of the pathophysiology of IARF, specific guidelines for its prevention and therapy have not been developed. Among triggering factors, peritonitis was present in half of all pediatric patients with this complication described in the English literature over the past 15 years. We report an additional nephrotic child who developed IARF following spontaneous bacterial peritonitis. The renal biopsy showed tubular epithelial changes consistent with acute tubular necrosis. A discussion of related literature and possible pathogenesis of this association is presented.
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  • 11
    ISSN: 1433-0350
    Keywords: Key words Child abuse ; Shaken baby syndrome ; Brain injury ; Infants ; Children ; Neuroimaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Acute CT/MRI findings were examined in a prospective, longitudinal study of 60 children 0–6 years of age hospitalized for moderate to severe traumatic brain injury (TBI). TBI was categorized as either inflicted (n=31) or noninflicted (n=29). Glasgow Coma Scale scores and perinatal history were comparable in both groups. Acute CT/MRI studies were visually inspected by a radiologist blind to group membership. Compared with the noninflicted TBI group, the inflicted TBI group had significantly elevated rates of subdural interhemispheric and convexity hemorrhages as well as signs of pre-existing brain abnormality, including cerebral atrophy, subdural hygroma, and ex vacuo ventriculomegaly. Intraparenchymal hemorrhage, shear injury, and skull fractures were more frequent after noninflicted TBI. Subarachnoid hemorrhage and infarct/edema occurred with comparable frequency in both groups. Characteristic acute neuroimaging findings of inflicted TBI included multiple extraaxial hemorrhages in addition to the mild atrophy, subdural hygromas, and ventriculomegaly that suggest prior brain abnormality.
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  • 12
    ISSN: 1433-0350
    Keywords: Key words Brain death ; Children ; Electroencephalogram ; Etiology ; Evoked potentials ; Radioisotopic angiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The objective of this study was to determine the main clinical, neurophysiological and angiographic findings in brain death (BD) in children seen at the Instituto Nacional de Pediatría, a third-level facility in Mexico City, between 1991 and 1996. The following variables were retrospectively analyzed: sex, age, etiology, associated morbidity, duration of stay in hospital, and the results of two of three confirmatory studies (electroencephalogram, evoked potentials, radioisotopic angiography). In all, 125 patients were studied [78 male; median age 2 years (range: 18 days to 17 years)]. The most frequent etiology was infection (34%); 57% of the children developed associated morbidity. In 111 of 122 patients electrocerebral silence was observed; 100 of 107 had brain stem and somatosensory evoked potentials affording conclusive evidence of BD; and 83 of 90 patients had a positive radioisotopic angiography indicating BD. In 76 patients all three confirmatory studies were performed: for 15 there was at least one false-negative test result. Our age cohort showed a predominance of children less than 2 years old. BD etiologies in developing countries differ from those reported in developed countries.
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Child's nervous system 16 (2000), S. 755-759 
    ISSN: 1433-0350
    Keywords: Keywords Head trauma ; Children ; CT scan ; MRI scan ; Follow-up
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  CT scanning is the current first imaging technique to be used after head injury, in those settings where a CT scan is available. The first scan is usually done without contrast enhancement. The value of CT is the demonstration of scalp, bone, extra-axial hematomas and parenchymal injury. It is rapid and easily done in the presence of the multiple monitors that many trauma patients have in place. It can be used to demonstrate the bony anatomy of the spine and is good for evaluation of abdominal and chest trauma also. MRI is more sensitive for all post-traumatic lesions other than skull fracture and subarachnoid hemorrhage, and can demonstrate parenchymal spinal cord injury. The cons are a longer scanning time, interference of the imaging by certain ICP monitors and problems with the positions of the monitoring equipment and ventilators outside the MRI magnetic field. MRI will be used increasingly to study early head injury because of its ability to measure cerebral blood flow, cerebral blood volume and the location and extent of cerebral edema. If the CT does not demonstrate pathology adequate to account for the clinical state, MRI is warranted. Follow up is best done with MRI as it is more sensitive to parenchymal change than is CT.
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  • 14
    ISSN: 1433-044X
    Keywords: Schlüsselwörter Thoraxtrauma ; Atelektasen ; Pädiatrie ; Bauchlage ; Keywords Thoracic trauma ; Atelectasis ; Children ; Prone position
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract We report on the ventilation in prone position in a 5-year-old traumatized child with severe thoracic and abdominal injuries (lung contusion, rib fractures, rupture of liver and spleen). Under continuous analgosedation, the young patient was ventilated in prone position for 6 h, since acute lung injury and atelectasis persisted despite various therapeutic measures (artifical ventilation in the pressure controlled mode, fiberoptic bronchoscopy, reexpansion maneuver). After initiation of the prone position, we observed a rapid increase i narterial oxygenation, which persisted in the following period. The hemodynamic situation remained stable. The complete disappearance of atelectasis was demonstrated radiologically after supine repositioning. After cessation of analgosedation, the extubation was performed 2 days later. Furthermore, we found no side effects of the prone position on the injured abdomen, and the liver function improved rapidly. Although there is a lack of experience with ventilation in prone position in pediatric intensive care, our report might be a recommendation for the indication of this technique in children.
    Notes: Zusammenfassung In dieser Kasuistik wird über die erfolgreiche Anwendung der Beatmung in Bauchlage bei einem 5-jährigen Mädchen berichtet, welches von einem Pkw überrollt worden war und sich Thorax- und Abdominalverletzungen (Rippenserienfraktur, Lungenkontusion, Leber- und Milzeinrisse) zugezogen hatte. Wegen des akuten Lungenversagens mit persistierenden Atelektasen, die durch wiederholte fiberoptische Bronchiallavagen und durch Reexpansionsmanöver nicht zu beheben waren, wurde der Entschluss zur 6-stündigen Lagerung auf den Bauch gefasst, obwohl über den Effekt dieser Lagerungsmaßnahme bei traumatisierten Kindern wenig bekannt ist und zu möglichen negativen Auswirkungen auf das schwerverletzte Abdomen eine Informationen vorliegen. Die Beatmung in Bauchlage führte zur raschen Verbesserung des pulmonalen Gesaustausches, die hämodynamische Situation wurde nicht beeinflusst. Die radiologische Kontrolle nach Rücklagerung zeigte eine vollständigen Rückgang der Atelektasen; die kleine Patientin konnte bald darauf extubiert werden. Weder laborchemisch noch klinisch wurde ein schädigender Einfluss auf das verletzte Abdomen gefunden. Die Beatmung in Bauchlage hat sich als Routineverfahren bei der Behandlung des Lungenversagens des Erwachsenen etabliert; nach der hier beschriebenen Erfahrung ist diese Maßnahme auch bei traumatisierten Kindern in Betracht zu ziehen, insbesondere wenn andere Maßnahmen nicht ausreichend sind.
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  • 15
    ISSN: 1433-0458
    Keywords: Schlüsselwörter Cochlear Implant ; Ambulante Rehabilitation ; Kinder ; Erwachsene ; Ergebnisse ; Keywords Cochlear implant ; Outpatient rehabilitation ; Cost effectiveness ; Results ; Children ; Adults
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Background and objective. This study compares the results of the outpatient-based program of the Cochlear Implant Center Ruhr with inpatient-based rehabilitation, which is almost exclusively performed in Germany. Patients/methods. The Department of Otorhinolaryngology at the University of Essen in Germany provided 52 patients with either 22- or 24-channel Nucleus cochlear implants from March 1996 to July 1999. Almost all patients (n=49) were rehabilitated on an outpatient basis, which is the standard in many cochlear implant centers outside Germany. Results. The longest follow-up period at the University of Essen Department of Otorhinolaryngology was 36 months. Minor complications occurred in 10% of the patients. After 24 months, the first three implanted patients were able to discriminate 100% of numbers and over 60% of syllables in the Freiburg speech discrimination test. The patients who developed an understanding of open speech were able to discriminate 31 words per minute with cochlear implant and without lipreading after 24 months. Children were seen to double their Schmid-Giovannini scores at 6 months postimplantation. Conclusions. The Essen outpatient-based cochlear implant program demonstrates results in speech development and speech understanding equal to those of centers providing inpatient rehabilitation. A special advantage is continuous rehabilitation with professionals known to the child for several years. In children especially, exhaustive commuting reduces school attendance and is a burden on the accompanying guardians. As an inpatient, however, the child is torn from his familiar environment. Parents with several children have particular difficulties in accompanying their child and indeed this may not always be possible.
    Notes: Zusammenfassung Hintergrund und Fragestellung. In dieser Arbeit werden die Ergebnisse der ambulanten Rehabilitation nach Cochlear-Implant-Versorgung mit denen der stationären Rehabilitation verglichen, die bisher in Deutschland fast ausschließlich durchgeführt wird. Von März 1996 bis Juli 1999 wurden an der Universitäts-Hals-Nasen-Ohren-Klinik Essen 52 taube oder an Taubheit grenzende Patienten mit einem 22-kanaligen bzw. 24-kanaligen Nucleuscochlear-Implant versorgt. Fast alle Patienten (n=49) konnten wohnortnah ambulant rehabilitiert werden, wie dies dem internationalen Standard entspricht. Ergebnisse. Der längste bisherige Nachbeobachtungszeitraum an der Universitäts-Hals-Nasen-Ohren-Klinik Essen sind 36 Monate. Nach 2 Jahren wurden von den 3 am längsten nachbeobachteten Patienten 100% der Zahlen und über 60% der Einsilber im Freiburger Sprachtest verstanden. Im “speech tracking” erreichten Patienten mit CI und ohne Lippenabsehen nach 24 Monaten 31 Wörter/min. Die Kinder zeigten 6 Monate nach Implantation eine Verdopplung des Scores im Test nach Schmid-Giovannini. Schlussfolgerungen. Das Essener Modell zeigt, dass eine ambulante Rehabilitation nach CI zu vergleichbaren Ergebnissen in der Sprachentwicklung und im Sprachverstehen führt, wie sie von anderen Zentren vorgelegt wurden, in denen fast ausschließlich stationär rehabilitiert wird. Besonders bei Kindern bedeuten lange Anfahrtswege mit einwöchigem stätionärem Aufenthalt Schulausfälle und eine Belastung für die begleitenden Eltern und Familienangehörigen zu Hause, sowie erhebliche Fahrtkosten. Stationäre Aufenthalte zur Rehabilitation reißen zudem das Kind aus seiner gewohnten Umgebung und sind für Eltern mit mehreren Kindern oft unmöglich.
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  • 16
    ISSN: 1433-0458
    Keywords: Schlüsselwörter Hörstörung ; Prävalenz ; Konnatale Hörstörungen ; Erworbene Hörstörungen ; Progredienz ; Infektionen ; Kinder ; Keywords Hearing loss ; Prevalence ; Connatal hearing loss ; Acquired hearing loss ; Progressive hearing loss ; Infections ; Children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract The results of international investigations on connatally acquired hearing loss are compared with the data of the German Registry on Childhood Hearing Loss (4058 cases). The connatal hearing disorders have shown a notable change in the last years regarding to aetiology and prevalence. In contrast to countries of the third world in developed nations the prevalence of permanent childhood hearing loss has been reduced down to 1 in 1.000 births. The results let assume a prevalence of approximately 1:1.200 births in Germany. For instance the number of rubella embryopathia decreased effectively. In contrast CMV infections and alcohol fetopathia are playing an increasing role. In the patients of the German Registry on Childhood Hearing Loss the percentage of certainly progressive hearing loss is 10.3 within the 4058 children with permanent hearing impairment. Diagnostic procedures first of all for the early diagnosis of CMV but also of toxoplasmosis are considerable because these infections may result in treatable hearing loss. Also consequent hearing tests are demanded in children with alcohol fetopathia.
    Notes: Zusammenfassung Im vorliegenden Beitrag werden die Daten internationaler Studien zu angeborenen erworbenen Hörstörungen mit den Ergebnissen aus 4058 Fällen im Deutschen Zentralregister für kindliche Hörstörungen (DZH) verglichen und ausgewertet. Die angeborenen Erkrankungen des Hörvermögens haben innerhalb der letzten Jahre bezüglich Ätiologie und Prävalenz einen deutlichen Wandel erlebt. Im Gegensatz zu Ländern der 3. Welt ist die Prävalenz permanenter kindlicher Hörstörungen in den westlichen Industrienationen auf ca. 1:1.000 gesunken. In Deutschland liegt die Prävalenz nach ersten Ergebnissen des DZH bei ca. 1,2:1.000. So ist beispielsweise der Anteil der Rötelnembryopathien stark zurückgegangen. Dagegen spielen heute die Zytomegalievirus-(CMV)-Infektion und die Alkoholfetopathie eine größere Rolle. Im Patientenkollektiv des DZH mit 4058 permanent hörgestörten Kindern beträgt der Anteil gesichert progredienter Verläufe 10,3%. Diagnostische Verfahren, vor allem zur Früherkennung von CMV und Toxoplasmose, gewinnen zunehmend an Bedeutung. Ebenso ist eine konsequente Hördiagnostik auch bei Kindern mit Alkoholfetopathie zu fordern.
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  • 17
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    Der Anaesthesist 49 (2000), S. 275-278 
    ISSN: 1432-055X
    Keywords: Schlüsselwörter Tropisetron ; postoperatives Erbrechen ; Adenotonsillektomie ; Antiemetika ; Kinder ; Key words Tropisetron ; PONV ; Adenotonsillectomy ; Antiemetics ; Children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Background: Postoperative nausea and vomiting (PONV) after tonsillectomy is a common problem in children. Tropisetron is a new 5HT3 receptor antagonist and is successfully used in paediatric patients receiving cancer therapy. The aim of the study was to assess efficacy and safety of a single intravenous dose of tropisetron for prevention of PONV in paediatric patients at risk for postoperative vomiting. Methods: In a randomised, double-blind, placebo-controlled trial, we studied 98 children aged 2–12 years undergoing tonsillectomy or adenotonsillectomy. Patients received placebo or tropisetron 0.1 mg (=0.1 ml)/kg body weight immediately after induction of anesthesia. A standard general anesthetic technique (Sevoflurane/N2O/O2 without neuromuscular blockers or opioids) was used. Perioperative vital signs, grade of sedation and episodes of postoperative nausea and vomiting were recorded. Results: No vomiting episodes occurred in 65.3% of the tropisetron treated patients compared to 34.7% of the placebo group (p=0.0024). Only 10.2% of the tropisetron treated patients vomited more than 3 times compared to 22.4% of the control patients (p=0.0004). The need for antiemetic rescue medication was significantly lower in the study group (10.4%) compared to 28.6% (p=0.025). No significant adverse effects of the study medication were shown. Conclusion: A single intravenous prophylactic dose of tropisetron effectively reduces the incidence of PONV during the first 24 postoperative hours after tonsillectomy and/or adenoidectomy. Because of the low incidence of adverse effects, the prophylactic use of tropisetron seems to be safe and justified in paediatric surgical patients at high risk for postoperative vomiting.
    Notes: Zusammenfassung Fragestellung: Erbrechen und Übelkeit nach Tonsillektomien bei Kindern sind ein häufiges Problem. Aufgrund der positiven Erfahrungen mit Tropisetron, einem neueren 5HT3 Rezeptor-Antagonisten bei Chemotherapien in der pädiatrischen Onkologie und mit anderen 5HT3 Rezeptor-Antagonisten in der Kinderchirurgie, prüften wir die Wirksamkeit und Sicherheit einer Einzeldosis Tropisetron zur Prävention von postoperativem Erbrechen bei chirurgischen Kindern mit erhöhtem Risiko für postoperatives Erbrechen. Methodik: Bei 98 Kindern im Alter von 2– 12 Jahren, die eine Tonsillektomie oder Adenotonsillektomie benötigten, führten wir eine randomisierte, doppelblinde, plazebokontrollierte Studie durch. Die Patienten erhielten Tropisetron oder Plazebo in einer Dosis von 0,1 mg (=0,1 ml)/kg KG i.v. unmittelbar nach der Narkoseeinleitung. Die Narkose erfolgte standardisiert mit Sevofluran/N2O/O2 ohne Einsatz von Opioiden und Muskelrelaxanzien. Vitalparameter, Sedationstiefe, das Auftreten von postoperativem Erbrechen und unerwünschte Wirkungen wurden aufgezeichnet. Ergebnisse: In der Tropisetrongruppe zeigten 65,3% der Kinder kein postoperatives Erbrechen, im Gegensatz zu nur 34,7% der Kinder in der Plazebogruppe (P=0,0024). Mehr als 3 Episoden von postoperativem Erbrechen zeigten nur 10,2% der Patienten in der Tropisetrongruppe im Vergleich zu 22,4% der Patienten der Kontrollgruppe (P=0,0004). Auch der Bedarf an antiemetischer Zusatzmedikation war in der Tropisetrongruppe mit 10,4% signifikant niedriger als in der Kontrollgruppe mit 28,6% (P=0,025). Bedeutsame Nebenwirkungen der Studienmedikation konnten nicht dokumentiert werden. Schlussfolgerungen: Eine prophylaktische intravenöse Einzelgabe von Tropisetron reduziert bei Kindern wirksam das Auftreten von postoperativem Erbrechen während der ersten 24 h nach einer Tonsillektomie oder Adenotonsillektomie. Die geringe Inzidenz von Nebenwirkungen rechtfertigt unserer Ansicht nach die prophylaktische Anwendung von Tropisetron bei Kindern nach Tonsillektomien.
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  • 18
    ISSN: 1432-1076
    Keywords: Key words Coeliac disease ; Children ; Iron deficiency anaemia ; Occult blood ; AbbreviationsCD coeliac disease ; ID iron deficiency ; GFD gluten-free diet
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract It has recently been suggested that in adults with coeliac disease, faecal blood loss may play a role in the development of iron deficiency. A group of 45 children diagnosed with coeliac disease during 1996 and 1997 were therefore prospectively evaluated for the presence of gluten in their diet, iron deficiency anaemia, and faecal occult blood. Sixty children admitted for elective surgery or asthma served as controls. Faecal occult blood was found in four iron deficient children on normal diet, of whom three were newly diagnosed. Occult blood loss disappeared in three of the four children when gluten was removed from their diet. Faecal occult blood was found in 26.7% of children on gluten-containing diet, but not in children on gluten-free diet (P=0.01), or in control children (P=0.001). Conclusion Our data suggest that the incidence of occult blood loss in coeliac disease occurs mainly in newly diagnosed cases and responds to a gluten-free diet. Occult blood testing may not be warranted in the absence of iron deficiency anaemia nor in children with iron deficiency anaemia who are on a gluten-free diet.
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  • 19
    ISSN: 1432-1076
    Keywords: Key words Gentamicin ; Once daily ; Children ; Saliva
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Gentamicin is widely used in paediatric medicine and therapeutic monitoring is mandatory due to the narrow margin of safety. Saliva sampling may be of potential interest, especially in children in whom blood sampling is often difficult. Experience with once daily intravenous administration of aminoglycosides has grown in recent years. Gentamicin levels were measured in serum and saliva of 55 children treated with the drug (5 mg/kg per day), administered intravenously in three different regimens: thrice (n=19), twice (n=18), and once daily (n=18). No correlation was found between serum gentamicin concentrations and saliva levels when the drug was administered twice or thrice daily, however, there was good correlation when the drug was administered once daily (r 2=0.96, P 〈 0.0001). Conclusion In children with uncomplicated infections treated with once daily gentamicin, trough concentrations of the drug can be monitored in saliva.
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  • 20
    ISSN: 1432-1076
    Keywords: Key words Sodium cromoglycate ; Children ; Exercise-induced asthma ; Urinary eosinophil protein X excretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This double-blind, randomised and cross-over study was designed to compare the preventive effect against exercise-induced bronchoconstriction (EIB), defined as the percentage decrease in FEV1≥15% after 6 min of exercise, of 2 mg and 10 mg of sodium cromoglycate (SCG), administered through a metered dose inhaler via spacer, in asthmatic children. Each of the 30 subject (age 11.6 ± 3.2 years) was tested on five occasions. For inclusion, EIB in test1 was required. In tests 2 to 5, all subjects inhaled 2 mg or 10 mg of SCG 20 min and 120 min before exercise in a randomised order. In order to assess excretion of eosinophil protein X (EPX) accompanying EIB, urine samples were collected before and after exercise. The mean percentage fall in FEV1 (±SD) in test 1 was 26.8 ± 9.8%. Inhalation of 2 mg and 10 mg of SCG 20 min before exercise provided a significant preventive effect in 83% and 77% and inhalation 120 min before exercise provided a preventive effect in 63% and 70%, respectively (n=30). Variance analysis did not reveal a statistically different absolute fall in FEV1 after exercise when both doses (120 min before exercise) were compared (P=0.356). In an unselected subgroup of 12 children, urinary EPX increased after the challenge without SCG premedication (test 1) (mean change: +48.7 μg/mmol creatinine, P=0.034), whereas no significant increase was found in case of SCG premedication (mean change in μg/mmol creatinine): 2 mg/20 min: +12.1; 2 mg/120 min: +8.5; 10 mg/20 min: −10.4 and 10 mg/120 min: −23.5; P 〉 0.1). Conclusion Administration of 10 mg of sodium cromoglycate is no more effective in preventing exercise-induced bronchoconstriction than 2 mg regardless of whether the medication is given 20 or 120 min before exercise. The preventive effect of sodium cromoglycate on exercise-induced bronchoconstriction in asthmatic children is associated with the inhibition of urinary eosinophil protein X excretion.
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  • 21
    ISSN: 1432-1076
    Keywords: Key words Health-related quality of life ; Health status ; Cross-cultural adaptation ; Children ; Health Utilities Index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Steady progress in developing effective treatments for childhood cancer and other severe pediatric diseases has established the need to consider the nature and frequency of late physical and psychological effects. The Health Utilities Index Mark 2 and Mark 3 (HUI2/3) systems were developed by Feeny, Furlong, Torrance et al. in Canada. These systems are generic multi-attribute measures of a person's health status and health-related quality of life. The first German version of the Canadian HUI2/3 questionnaire was created in our clinic, following recommended guidelines for cross-cultural adaptation of health-related quality of life measures. The usefulness of the resultant version was investigated using a sample of 142 patients who presented to our oncological outpatients' department for a routine health care visit after completion of treatment. The 15 items of the HUI2/3-questionnaire were answered independently by three groups of assessors – nurses, physicians, and parents or patients. Two additional questions covered ratings of the severity of treatment effects and the specification of these effects. The questionnaire was both easy to use and acceptable to the assessors. Percentage agreement between observers about levels for individual attributes ranged from 56% to 100%, with the lowest agreement on the subjective attributes of emotion, pain and cognition. These results are in accordance with previous studies using the original instrument. HUI2 global utility scores were significantly related to ratings of treatment sequelae, giving support to the discriminant validity of the measure. Conclusion The German version of HUI2/3 is a useful instrument with generally high inter-observer agreement and good suitability for outcome measurement in childhood cancer patients. Further research is needed to assess the usefulness of the instrument in other clinical populations and its sensitivity in longitudinal studies.
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  • 22
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    European journal of pediatrics 159 (2000), S. 515-519 
    ISSN: 1432-1076
    Keywords: Key words Osteogenesis imperfecta ; Hearing loss ; Children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Osteogenesis imperfecta (OI) is a genetic disorder of connective tissue. Progressive hearing loss is one of the principal symptoms of OI, affecting about 50% of adult patients. Hearing loss may also occur in childhood and results in additional disability in education and psychosocial adaptation and aggravates the physical handicap. This can be avoided by appropriate otological and audiological treatment. In a nationwide search, 254 Finnish patients with OI were identified indicating a prevalence of 4.9/100 000. Of the 60 children, 45 aged between 4 and 16 years accepting to participate the study on hearing, were evaluated by a questionnaire and clinical audiometry. Hearing loss was defined as pure tone average (PTA0.5–2 kHz) more than 20 dB hearing level (HL). A clinical geneticist determined the type of OI among the 45 patients. Two sporadic OI cases with conductive hearing loss were ascertained (4.4%): An 11-year-old girl with type IV OI with a PTA0.5–2 kHz of 35/40 dB HL and a 15-year-old boy with type IV OI with a PTA0.5–2 kHz of 27/18 dB HL. In addition, a 6-year-old girl with familial OI type I had either a congenital sensorineural deafness or early progressive deafness with PTA0.5–2 kHz of 97/103 dB HL, probably of unrelated aetiology. Conclusion Hearing loss in children with osteogenesis imperfecta is less frequent than generally suspected. Nevertheless, it is recommended that audiometry is performed in children with osteogenesis imperfecta even without symptoms of hearing loss at the age of 10 years, and repeated every 3 years thereafter.
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  • 23
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    European journal of pediatrics 159 (2000), S. 430-433 
    ISSN: 1432-1076
    Keywords: Key words Alport syndrome ; Angiotensin-converting enzyme inhibitors ; Proteinuria ; Children ; AbbreviationACEi angiotensin-converting enzyme inhibitor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Enalapril, a long-acting inhibitor of angiotensin-converting enzyme, was given for 2 years to seven children with Alport syndrome. Five patients had a classical X-linked form of the disease; two siblings had the autosomal recessive variant. Their age was between 5.15 and 13.75 years when enalapril was started. All patients had haematuria and proteinuria, creatinine clearance was 〉80 ml/min per 1.73 m2 in all, and only one patient was hypertensive. The starting dose of enalapril (0.1 mg/kg body weight per day) was increased progressively according to individual clinical tolerance. The median doses were 0.13, 0.12, 0.21 and 0.29 mg/kg at 6, 12, 18 and 24 months, respectively. Median values of mean blood pressure were 95 mmHg at the start and 84 mmHg after 24 months. Median daily proteinuria decreased from 52 mg/kg to 18 mg/kg at 6 months, 21 mg/kg at 12 months, 12 mg/kg at 18 months and 30 mg/kg at 24 months. Serum creatinine increased over time from a median of 0.64 mg/dl at baseline to 0.77 mg/dl at 24 months. Concomitantly, there was a decrease in GFR from 104 to 83 ml/min per 1.73 m2 at 18 months and an increase again to 95 ml/min per 1.73 m2 at 24 months. Analysis of the individual data showed three patterns: no response (n=2), temporary response (n=2) and sustained response (n=3). Conclusion When given enalapril at the dosages mentioned, Alport patients as a group display a marked reduction in urinary protein excretion with a nadir of 23% of the baseline figure at 18 months, a decrease that cannot be accounted for by the slight decrease in glomerular filtration rate. Although these are preliminary data, it is recommended to try an angiotensin-converting enzyme inhibitor in every paediatric Alport patient with proteinuria.
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  • 24
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    European journal of pediatrics 159 (2000), S. 575-578 
    ISSN: 1432-1076
    Keywords: Key words Haemophilia ; HIV-negative patients ; Children ; Growth ; Body mass index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract It has been shown that HIV-positive haemophilic children develop growth retardation. As not only the HIV infection but also other disease-related factors might compromise growth in these children, growth data were analysed in a longitudinal cross-sectional manner in 84 HIV-negative haemophilic patients from two university clinics. A total of 2–24 height and weight measurements (median 6) were recorded in each patient resulting in 683 single values collected between 1977–1995. Height SDS of all haemophilic boys was −0.31 ± 2.13 (mean ± SD, NS versus 0) and body mass index SDS was 0.21 ± 3.49 (mean SD, NS versus 0) at first measurement and remained unchanged throughout the observation period. Neither height nor body mass index differed with respect to the severity of haemophilia (mild/moderate/severe) or the study centre (Vienna/Prague). Conclusion Growth in HIV-negative patients with haemophilia is not affected in spite of the immunological abnormalities attributed to the substitution therapy or the bleeding episodes in the joints with the potential effect on the growth plate.
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  • 25
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    European journal of pediatrics 159 (2000), S. 649-656 
    ISSN: 1432-1076
    Keywords: Key words Antiretroviral therapy ; Children ; AIDS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The introduction of combination antiretroviral therapy has been associated with a dramatic clinical improvement in children with human immunodeficiency virus infection. However, the uptake of antiretroviral therapy has been variable across Europe. The Paediatric European Network for the Treatment of AIDS Steering Committee has performed a systematic literature review of paediatric antiretroviral therapy trials. An analysis of the evidence base for the commencement and maintenance of antiretroviral therapy was produced. Suggestions for when to commence antiretroviral therapy, which drugs to start with and how to monitor and sequence drug regimens are given. Conclusion The aim of these guidelines is to help in obtaining equity of access to a uniformly high standard of care for children with human immunodeficiency virus infection in all European countries.
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  • 26
    ISSN: 1432-1076
    Keywords: Key words Insulin aspart ; Insulin analogue ; Type 1 diabetes ; Pharmacokinetics ; Children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The pharmacokinetics of the novel, rapid-acting insulin aspart were compared with those of soluble human insulin following subcutaneous administration in nine children (aged 6–12 years) and nine adolescents (aged 13–17 years) with stable type 1 diabetes. The study had a randomised, double-blind, two-period crossover design. Each patient received a single subcutaneous dose of insulin aspart or human insulin (0.15 IU/kg body weight) 5 min before breakfast and the plasma insulin and glucose concentrations were measured at intervals during the following 5 h. The pharmacokinetic profile of insulin aspart differed significantly from that of human insulin with a higher mean maximum serum insulin (Cmax ins), 881 ± 321 (SD) pmol/l versus 422 ± 193 pmol/l for human insulin (P 〈 0.001); and with a shorter median serum insulin t max ins, 40.0 min (interquartile range: 40–50 min) versus 75.0 min (interquartile range: 60–120 min) for human insulin, (P 〈 0.001). An age-related effect on Cmax ins and area under the curve (AUC0–5h ins) was observed with higher values in adolescents than in children for both insulin aspart and human insulin. Postprandial glycaemic control was improved with insulin aspart; the baseline-adjusted ΔCmax glu being lower for insulin aspart compared with human insulin (increase of 7.6 ± 5.1 versus 9.4 ± 4.4 mmol/l respectively, P 〈 0.05). The incidence of adverse events was similar for the two insulin types. Conclusion The more rapid onset of action of insulin aspart versus human insulin, previously observed in adults, is confirmed in a paediatric population with type 1 diabetes.
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  • 27
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    European journal of pediatrics 159 (2000), S. 507-508 
    ISSN: 1432-1076
    Keywords: Key words Behçet disease ; Children ; Myositis ; Pustulosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A 12-year-old boy presented with a limp and findings suggesting localised myositis of his right calf and a working diagnosis of Behçet disease was made. During 3 years of follow-up, he had another three episodes of calf myositis, all responsive to corticosteroids within days. Conclusion A case of recurrent localised myositis as a main manifestation of Behçet disease is reported. The evolution of incomplete Behçet disease, which is common in children, to the full blown form, with the emphasis on muscle involvement and the importance of early diagnosis of Behçet disease, is discussed.
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  • 28
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    European journal of pediatrics 159 (2000), S. 530-534 
    ISSN: 1432-1076
    Keywords: Key words Schistosomiasis ; Children ; Travellers ; Ultrasonography ; Immunodiagnosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Reports on schistosomiasis in children growing up in Europe are rare despite increased travel activity. We report on eight male and three female German children aged 50 months to 15 years with schistosomiasis. Six children were asymptomatic, whereas two presented with typical signs of Katayama fever. Persisting haematuria, headache with eosinophilia and pyelonephritis were observed in one child each. An exposure was reported for six of the children. Two were examined solely because schistosomiasis was diagnosed in a family member. All had antibodies against schistosomal antigens in at least two of three screening tests. However, schistosomal ova (Schistosoma haematobium) were detected in urine and faecal specimens from only three children. A tumour-like lesion of the bladder was found by ultrasound in only one of the children who also exhibited haematuria. Neither eosinophilia nor elevated IgE levels were constant findings. Six to 12 months after praziquantel treatment, parasitological and ultrasound checks were negative and levels of specific antibodies decreased. However, 2 years later, elevated antibody levels were detected in one girl without evidence of any new exposure. She became antibody-negative 1 year after a second course of treatment. Conclusion In contrast to residents of endemic areas, parasitological and ultrasound examinations seem to be inferior to immunodiagnostics in children from non-endemic areas at temporary risk for schistosomiasis.
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  • 29
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    Der Hautarzt 51 (2000), S. 95-100 
    ISSN: 1432-1173
    Keywords: Schlüsselwörter Dubowitz-Syndrom ; Atopisches Ekzem ; Monozygote Zwillinge ; Kinder ; Keywords Dubowitz syndrome ; Atopic eczema ; Monozygotic twins ; Children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Autosomal recessive inheritance, intrauterine growth retardation, short stature, microcephaly, distinct facial dysmorphism, psychomotoric retardation, and often uncharacterized eczematous skin lesions distinguish the rare Dubowitz syndrome. Here a pair of monozygotic twins with Dubowitz syndrome and clear-cut atopic eczema is presented.
    Notes: Zusammenfassung Autosomal rezessiver Erbgang, intrauterine Wachstumsretardierung, Kleinwüchsigkeit, Mikrozephalie, charakteristische Gesichtsdysmorphie, psychomotorischer Entwicklungsrückstand sowie häufig nicht näher charakterisierte ekzematöse Hautveränderungen kennzeichnen das seltene Dubowitz-Syndrom. Wir berichten über monozygote Zwillinge mit Dubowitz-Syndrom und eindeutigem atopischen Ekzem.
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  • 30
    ISSN: 1432-1173
    Keywords: Schlüsselwörter Atopisches Ekzem ; Kinder ; Elternschulung ; Video ; Mütter ; Key words Atopic eczema ; Parental education ; Video ; Children ; Mothers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Background and Objective. Psychological problems in children and parents related to children's atopic eczema (AE) may impede the success of treatment. We studied the question, if behavior-based parental education in groups (DPE) or standardized video-education (VPE) could enhance dermatological treatment effects and reduce skin-damaging behaviors in children and stress in their mothers. Patients/Methods. 47 mothers attending the university outpatient-clinic for dermatology and their AE-children (mean age 4 years) participated in the study. 18 mothers underwent the DPE (10 sessions), 15 mothers worked with VPE at home. Dermatological standard treatment (CG; N=14) served as control for a 16-weeks-evaluation-period. Results. AE-symptoms improved overall, but the effectiveness of the treatments differed significantly, improval with parent education and was best with VPE. Psychological problems of mothers were equally reduced with DPE and VPE. Conclusions. It is suggested that VPE is a cost effective and less time consuming method for supporting dermatological therapy of AE in children.
    Notes: Zusammenfassung Hintergrund und Fragestellung. Das atopische Ekzem (AE) im Kindesalter kann psychologische Probleme bei Kind und Eltern zur Folge haben, die den Behandlungserfolg erschweren. Die Effektivität direkter verhaltensorientierter Elterngruppenschulungen (DES) bzw. standardisierter Videoschulungen (VES) gegenüber der dermatologischen Standardbehandlung (KG) zur Besserung des AE, des Kratzverhaltens der Kinder und krankheitsbedingter Belastungen der Mütter wurde überprüft. Patienten/Methodik. An der Studie nahmen 47 Mütter und deren AE-Kinder (Durchschnittsalter 4 Jahre) aus der Neurodermitisambulanz der Universitätshautklinik teil, 18 Mütter besuchten die DES (10 Gruppensitzungen), 15 Mütter arbeiteten mit der VES zu Hause. Die Behandlung der KG (n=14) erfolgte im vergleichbaren 4-Monats-Zeitraum. Ergebnisse. Das AE war über alle Behandlungsbedingungen gebessert, ihre Effekstärken unterschieden sich jedoch signifikant: Elternschulungen waren effektiver als Standardbehandlung, den stärksten Effekt hatte die VES. Belastungen der Mütter reduzierten sich nach beiden Schulungsformen. Schlussfolgerungen. Die Ergebnisse verweisen auf eine Zeit und Kosten sparende Möglichkeit, Videoschulungen für die Unterstützung der Therapie des AE im Kindesalter zu nutzen.
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  • 31
    ISSN: 1432-1173
    Keywords: Schlüsselwörter Dermatologie ; Primary Health Care ; Langzeitergebnisse ; Kinder ; Kenia ; Keywords Dermatology ; Primary health care ; Long-term effects ; Children ; Kenya
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Background and Objective. In spite of the importance of skin diseases in Africa south of the Sahara, dermatology is insufficiently represented within the established primary health care systems. Aim of this study was to find out whether an integrated dermatology project could reduce the prevalence of dermatoses. Patients/Methods. Since 1994 trained community health workers have carried out regular weekly visits to schools and nurseries in 10 communities in rural western Kenya. Epidemiological studies were done in 13 schools in 4 communities involving 5780 and 4961 pupils one year before (1993) and 5 years (1999) following the introduction of the dermatology project. Results. Within this period the prevalence of bacterial skin infections fell from 12.7% to 11.3% (n.s.). Mycoses rose from 10.1% to 13.9% (p〈0.05), while arthropod infections (mainly scabies) remained unchanged with a prevalence of 8.3% in 1993 and 8.0% in 1999 (n.s.). Dermatitis also showed no changes (1.7% in both years). Conclusions. The prevalence of infective dermatoses depends not only on medical treatment but also far more on socio-economic factors.
    Notes: Zusammenfassung Hintergrund und Fragestellung. Trotz der großen Bedeutung der Dermatosen in Schwarzafrika ist die Dermatologie in den dort etablierten Basisgesundheitsdiensten völlig unzureichend repräsentiert. Untersucht werden sollten die Langzeitauswirkungen eines in das Primary Health Care-System integrierten Dermatologieprojekts in Bezug auf die Prävalenz von Hauterkrankungen. Patienten/Methodik. Seit 1994 besuchen ausgebildete Community Health Workers einmal wöchentlich Schulen und Vorschulkindergärten in 10 Gemeinden im ländlichen Westkenia. In 13 Schulen von 4 Gemeinden wurden 1 Jahr vor (1993) und 5 Jahre nach (1999) Projektinitiierung Reihenuntersuchungen an 5780 bzw. 4961 Kindern durchgeführt. Ergebnisse. Innerhalb dieses Zeitraums sank die Prävalenz bakteriell bedingter Dermatosen von 12,7% auf 11,3% (n.s.). Bei den Mykosen fand sich ein Anstieg von 10,1 auf 13,9% (p〈0,05). Arthropodenbedingte Infektionen (vorwiegend Skabies) blieben mit 8,3% 1993 und 8,0% 1999 (n.s.) im Wesentlichen gleich. Ekzeme wiesen zu beiden Zeitpunkten eine Prävalenz von 1,7% auf. Schlussfolgerungen. Die Prävalenz infektiöser Dermatosen hängt nur zu einem geringen Teil von der medizinischen Versorgung, sondern überwiegend von sozioökonomischen Faktoren ab.
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  • 32
    ISSN: 1129-2377
    Keywords: Key words Coeliac disease ; Headache ; Children ; HLA antigens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The linkage between HLA antigens and disease susceptibility has been investigated in several diseases. Two different mechanisms are known to act in the relation between the HLA system and headache: linkage and association of alleles. Among neurological disorders associated with coeliac disease (CD) we focused on headache in 1997. From a group of 70 coeliac children, we studied 10 children with headache (3 boys and 7 girls). For each subject we evaluated clinical history and HLA antigens. The incidence of headache was not different with respect to the prevalence of headache in the general population. The HLA setting is not different between the 2 groups examined. However, we highlight 2 cases for the particular HLA setting.
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  • 33
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    The journal of headache and pain 1 (2000), S. 169-172 
    ISSN: 1129-2377
    Keywords: Key words Migraine ; Sleep ; Sleep apnea ; Children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In our previous study we found a high prevalence of disordered sleep breathing in migraine children vs. controls. Since no quantitative studies about sleep respiratory disorders have been carried out in migraine children, we performed a polysomnographic (PSG) study in 10 migraine patients (7 boys, 3 girls; mean age 8.11 years, range, 5.8–14.5) attending the Headache Center of our department, to evaluate the presence of sleep apnea. Mothers completed a headache diary and a sleep diary for at least 1 month and filled out a sleep questionnaire. PSG data showed a normal sleep architecture in 3 cases, an insomnia pattern in 2, a reduction of slow wave sleep in 3 and a reduction of REM sleep in 2. Respiratory analysis revealed that 2 of 10 patients had obstructive sleep apnea. These 2 patients presented habitual snoring and associated sleep disturbances such as restless sleep and hypnic jerks. Sleep apnea may be a subtle and often undiagnosed symptom in several migraine patients. The report of habitual snoring associated with other sleep disturbances such as restless sleep and other parasomnias may be a sign of sleep apnea in migraine children.
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  • 34
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    Pflügers Archiv 440 (2000), S. r200 
    ISSN: 1432-2013
    Keywords: Key words oxygen uptake ; kinetics ; threshold
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The linear relationship between oxygen consumption (Vo2) and exercise intensity is a well established phenomenon observed during incremental exercise. Recently, a non-linear increase in Vo2 has been reported by Zoladz et al., who used a relatively complicated method to describe the phenomenon. In this study, we tried to ascertain whether the same phenomenon, which we named the oxygen uptake threshold (OUT), could be described by a simple method, using the two best fitting lines adopted for the less and more steep parts of the Vo2 increase. Our hypothesis was that the non-linear Vo2 increase was the result of a continuous Vo2 increase (oxygen drift) occurring during the more intense steps only. Therefore, we analysed the Vo2 time course during each step. Six cyclists performed an incremental exercise test on a cyclo - ergometer. The lactate threshold (LT) was calculated by using the intersection point of the two best fitting lines in the diagram of log LA (lactate concentration) dependence on log P (Power). The time course of Vo2 during each step was analysed by an exponential rise to the maximum model. The results showed that OUT could be determined in five of the six subjects, whereas LT could be determined in all six subjects. The power output determined by OUT (168 ± 13 W) was similar to that determined by LT (180 ± 25 W). The Vo2 time course during each step showed steady values during low intensity exercise. At intensities above LT and OUT, however, Vo2 increased continuously, showing oxygen drift. It may be concluded that OUT is a realistic phenomenon, which is based on oxygen drift.
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  • 35
    ISSN: 1468-2869
    Keywords: Asthma ; Children ; Chronic illnesses ; Diabetes ; Self-help ; Training
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Abstract A randomized field trial of a child-centered model of training for self-management of chronic illnesses was conducted of 355 Spanish-speaking school-aged children, between 6 and 15 years old, with moderate to severe asthma and epilepsy, in Buenos Aires, Argentina. The model, based on play techniques, consists of five weekly meetings of 8–10 families, with children's and parents' groups held simultaneously, coordinated by specially trained teachers and outside the hospital environment. Children are trained to assume a leading role in the management of their health; parents learn to be facilitators; and physicians provide guidance, acting as counselors. Group activities include games, drawings, stories, videos, and role-playing. Children and parents were interviewed at home before the program and 6 and 12 months after the program, and medical and school records were monitored for emergency and routine visits, hospitalizations, and school absenteeism. In asthma and epilepsy, children in the experiment showed significant improvements in knowledge, beliefs, attitudes, and behaviors compared to controls (probability of experimental gain over controls=.69 for epilepsy and .56 for asthma, with σ2= .007 and .016, respectively). Parent participants in the experiment had improved knowledge of asthma (39% before vs. 58% after) and epilepsy (22% before vs. 56% after), with a probability of gain=.62 (σ2=.0026) with respect to the control group. Similar positive outcomes were found in fears of child death (experimental 39% before vs. 4% after for asthma, 69% before vs. 30% after for epilepsy), as well as in disruption of family life and patient-physician relationship, while controls showed no change. Regarding clinical variables, for both asthma and epilepsy, children in the experimental group had significantly fewer crises than the controls after the groups (P=.036 andP=.026). Visits to physicians showed a significant decrease for those with asthma (P=.048), and emergency visits decreased for those with epilepsy (P=.046). An 18-item Children Health Locus of Control Scale (CHLCS) showed a significant increase in internality in experimental group children with asthma and epilepsy (P〈.01), while controls did not change or performed worse 12 months after the program. School absenteeism was reduced significantly for those with asthma and epilepsy (for the group with asthma, fall/winterP=.006, and springP=.029; for the group with epilepsy,P=.011). Conclusion The program was successful in improving the health, activity, and quality of life of children with asthma and epilepsy. The data suggested that an autonomous (Piagetian) model of training is a key to this success, reinforcing children's autonomous decision making.
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  • 36
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    Journal of thermal analysis and calorimetry 59 (2000), S. 807-814 
    ISSN: 1572-8943
    Keywords: facial and meridional Co(III) complexes ; kinetics ; thermodynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Thermal properties of facial and meridional uns-cis-[Co(eddp)gly]0.5H2O complexes were investigated by means of DSC and TG techniques. It wasshown that the processes of thermal decomposition of these complexes are multi-stepdegradation processes, which can also be well separated into individual steps, depending onthe molecular symmetry. Thus, the process of thermal degradation of the meridional isomerof the above complex consists of 4 well-separated steps in the temperature interval from 100to 500°C. The corresponding kinetic and thermodynamic parameters of this process weredetermined, and a possible mechanism is discussed.
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  • 37
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    Journal of thermal analysis and calorimetry 61 (2000), S. 805-818 
    ISSN: 1572-8943
    Keywords: aluminium ; ARC ; DSC ; kinetics ; nanometric size ; SDT ; TG
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The thermal properties of Alex, a nanosized Al powder, were determined using various techniques, including DSC, TG, simultaneous TG-DTA (SDT) and accelerating rate calorimetry (ARC). The results demonstrate that the specific heat capacities of nano and micron size Al powders are similar between 30 and 400°C. Dynamic and isothermal methods were used to determine the kinetic parameters for the oxidation reaction of Alex, which was detected at an onset temperature of 481°C. The results obtained were in good agreement with each other. From the ARC experiments, exotherms were detected near 340 and 260°C for experiments started at ambient pressure and at 0.72 MPa, respectively.
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  • 38
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    Journal of thermal analysis and calorimetry 61 (2000), S. 955-965 
    ISSN: 1572-8943
    Keywords: kinetics ; metal complexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Thermogravimetry (TG) and differential thermal analysis (DTA) were performed on the complexes with general formula (M(DEBT)n (where M =Fe, Co, Ni, Cu or Ru; n =2, or 3 and DEBT=N,N-diethyl-N'-benzoylthiourea). Derivative thermogravimetric (DTG) curves were also recorded in order to obtain decomposition data on the complexes. The complexes of Fe(III), Co(II), Ni(II), Cu(II) and Ru(III) displayed two- or three-stage decomposition patterns when heated in a dynamic nitrogen atmosphere. Mass loss considerations relating to the decomposition stages indicated the conversion of the complexes to the sulfides or to the corresponding metal alone (Cu, Ru, NiS, CoS or FeS). Mathematical analysis of the TG and DTG data showed that the order of reaction varied between 0.395 and 0.973. Kinetic parameters such as the decomposition energy, the entropy of activation and the pre-exponential factor are reported.
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  • 39
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    Journal of thermal analysis and calorimetry 62 (2000), S. 353-363 
    ISSN: 1572-8943
    Keywords: controlled environment ; high-T c superconductors ; kinetics ; microgravimetric investigations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Many properties of oxide superconductors depend on the oxygen concentration and its distribution in the samples. The microgravimetric method is very useful to study of oxide superconductors, as it allows investigations in vacuum and controlled environments in classical applications: thermogravimetric analysis for the study of solid-state reactions, determinations of oxygen contents in redox reactions and the combined measurement of mass and additional parameters, e.g. evolved gas analysis etc. Single-phase samples of high-temperature superconductors were synthesized from stoichiometric mixtures of high-purity oxides and carbonates. Appropriate amounts of the precursor powders were homogenized manually or by a mechanical ball mill and subsequently calcined at temperatures in the 800 to 950°C range with intermediate grinding to ensure homogenous reaction. The lattice parameters of all preparations were controlled, in both initial and final experiments, by the X-ray powder method (CuKα radiation), using a Stadi P (Stoe) diffractometer with a position-sensitive detector. It is well known that temperature and mass can be measured with an accuracy higher by orders of magnitude than it is still possible for the thermoanalyst to determine the transformation temperatures or the mass changes due to overlapping partial reactions. Applications of Cahn microbalance to study of high-temperature superconductors are presented.
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  • 40
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    Structural chemistry 11 (2000), S. 341-346 
    ISSN: 1572-9001
    Keywords: Positronium chemistry ; kinetics ; spin-exchange reactions ; high- and low-spin 3d complexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Continuing in our work on the correlations between the rate constants, k CR, of the ortho into para-positronium conversion reactions, CR, promoted by complexes of various 3d ions and the metal electron delocalization β caused by the ligands, the relationship between the parameters of the correlation lines pertinent to highand low-spin complexes of CrII, MnII, and CoII ions was ascertained. Moreover, it was experimentally verified, for the first time, that the statistical probability of the CR promoted by paramagnetic compounds with S = 1/2 is three times larger than that of the CR caused by compounds with S 〉 1/2.
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  • 41
    ISSN: 1436-3771
    Keywords: Key words Age ; Children ; Dental fluorosis ; Severity ; Tooth eruption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The purpose of this study was to investigate the influence of age on the severity of dental fluorosis in children exposed to drinking water with either low or high fluoride concentrations. The children selected for this study were aged 10–14 years, with 28 permanent teeth and at least 1 tooth pair with fluorosis. The children were permanent residents of districts in western Uganda with either 0.5 mg (n=33) or 2.5 mg fluoride/l in drinking water (n=186). All vestibular tooth surfaces were examined for fluorosis using the modified Thylstrup and Fejerskov (TF) index. In the high fluoride community, the proportion of teeth per child with TF scores ≥4, and ≥5 was significantly higher among children aged 13–14 years compared to those aged 10–12 years. Children’s chronological age correlated positively and significantly with the median TF scores for all teeth, including early erupting (first molars and incisors) and late erupting teeth (canines, premolars and second molars). In linear regression analyses, the median TF score for all teeth, as well as for early erupting and late erupting teeth, increased significantly with age. On the other hand, in the low fluoride community there was no significant association between age and the severity of fluorosis. This study showed a significant increase in the severity of fluorosis with increasing age in a high fluoride community, whereas no change in severity with age was observed in a low fluoride community.
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  • 42
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    Trauma und Berufskrankheit 2 (2000), S. S138 
    ISSN: 1436-6274
    Keywords: Schlüsselwörter ; Vorderes Kreuzband ; Kind ; Wachstumsfuge ; Fehlwachstum ; Key words ; Anterior cruciate ligament ; Children ; Growth plate ; Growth disturbance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Lesions of the anterior and posterior cruciate ligaments are relatively rare in childhood and adolescence; in this age group they need even more consistent and aggressive treatment than in adults as far as conservation of the menisci and definitive stabilization are concerned. Virtually no cases in which serious growth disturbance has arisen following transepiphyseal drilling are known from the literature. Thus, cruciate ligament suturing should also not be done in children, because the long-term efficacy has not been confirmed. The operative procedure is presented in detail and is related to bone age. Early transepiphyseal drilling is permissible.
    Notes: Zusammenfassung Ligamentäre Kreuzbandverletzung beim Kind und im Adoleszentenalter sind relativ selten, sie bedürfen im Vergleich zum Erwachsenen ¶einer noch konsequenteren und aggressiven Behandlung bezüglich Meniskuserhalt und definitiver Stabilisierung. In der Literatur sind praktisch keine Fälle bekannt, bei denen es tatsächlich zu einem gravierenden Fehlwachstum nach transepiphysärer Bohrung gekommen ist. Insofern sollte auch die Kreuzbandnaht beim Kind wegen der nicht bewiesenen Langzeiteffizienz unterlassen werden. Das Vorgehen im Einzelnen in Bezug zum Skelettalter wird dargestellt. Frühzeitige transepiphysäre Bohrungen sind erlaubt.
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  • 43
    ISSN: 1432-2277
    Keywords: Key words Liver transplantation ; Children ; Risk factors for survival ; Primary non-function ; Hepatic artery thrombosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Several recipient, donor and operation factors as well as postoperative complications related to patient survival after liver transplantation (LT) in children were studied by univariate and multivariate analyses . In a 13-year period, 103 patients under 15 years of age underwent 120 LT; the mean age was 63 months and 36 % were under 2 years of age. Indications for LT were cholestatic disease in 68 (56 %), metabolic diseases in 18 (14 %), fulminant hepatic failure in 8 (7.5 %), cirrhosis in 7 (5.8 %), and retransplants in 17 (14 %). Whole liver was transplanted in 79 % of cases and partial liver in 21 %. Actuarial survival at 1, 5, and 10 years was 70 %, 61 %, and 57 %, respectively. United Network of Organ Sharing (UNOS) I recipients (RR = 2.7), primary non-function (PNF) (RR = 13.9), and hepatic artery thombosis (HAT) (RR = 3.8) were independent factors for lower patient survival in multivariate analysis. Thus, in our experience, postoperative mortality as a consequence of the patient's condition before transplantation, or complications such as PNF or HAT, are the major causes of decreased survival in pediatric LT.
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  • 44
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    Catalysis letters 64 (2000), S. 65-75 
    ISSN: 1572-879X
    Keywords: NO reduction ; CH3OH ; La2O3 ; methyl nitrite ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Nitric oxide (NO) reduction by methanol was studied over La2O3 in the presence and absence of oxygen. In the absence of O2, CH3OH reduced NO to both N2O and N2, with selectivity to dinitrogen formation decreasing from around 85% at 623 K to 50–70% at 723 K. With 1% O2 in the feed, rates were 4–8 times higher, but the selectivity to N2 dropped from 50% at 623 K to 10% at 723 K. The specific activities with La2O3 for this reaction were higher than those for other reductants; for example, at 773 K with hydrogen a specific activity of 35 μmol NO/s m2 was obtained whereas that for methanol was 600 μmol NO/s m2. The Arrhenius plots were linear under differential reaction conditions, and the apparent activation energy was consistently near 14 kcal/mol with CH3OH. Linear partial pressure dependencies based on a power rate law were obtained and showed a near‐zero order in CH3OH and a near‐first order in H2. In the absence of O2, a Langmuir–Hinshelwood type model assuming a surface reaction between adsorbed CH3OH and adsorbed NO as the slow step satisfactorily fitted the data, and the model invoking two types of sites provided the best fit and gave thermodynamically consistent rate constants. In the presence of O2 a homogeneous gas‐phase reaction between O2, NO, and CH3OH occurred to yield methyl nitrite. This reaction converted more than 30% of the methanol at 300 K and continued to occur up to temperatures where methanol was fully oxidized. Quantitative kinetic studies of the heterogeneous reaction with O2 present were significantly complicated by this homogeneous reaction.
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  • 45
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    Adsorption 6 (2000), S. 349-357 
    ISSN: 1572-8757
    Keywords: sulfadiazene ; adsorption ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract To investigate the nature of interactive forces between sulfadiazene molecules and alumina surface the experiments were performed for the adsorption of sulfadiazene (SD) from its aqueous sulution onto the alumina surfaces at 25 ± 0.2°C and the influence of factors such as increasing concentration of SD (4.0–20.0 × 10−3 mol cm−3), the time required for adsorption equilibrium, pH (2.0–12.0) and temperature (5–45°C) of the adsorption medium, the presence of ions like Cl−, SO2− 4 and PO3− 4 (0.01–0.30 M) and organic solvents (5% v/v) were observed on the course of adsorption of SD. Various adsorption and kinetic parameters such as adsorption coefficient, the rate constants for adsorption and desorption were also evaluated. The results of the above cited studies facilitated to formulate the mechanisms of interaction between SD and alumina surfaces. From application view point the present work may be a potential tool for an effective chromatographic separation of sulfa drugs from industrial effluents.
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  • 46
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    Catalysis letters 69 (2000), S. 103-107 
    ISSN: 1572-879X
    Keywords: dicyclopentadiene ; Wacker oxidation ; Pd(AcO)2 ; benzoquinone ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The oxidation of dicyclopentadiene catalyzed by palladium(II) acetate and benzoquinone in the presence of perchloric acid was studied. Tricyclodecenone in high selectivity (85–98%) at a conversion of dicyclopentadiene up to 76% was obtained. The kinetic model assumed the significant inhibition complexation between dicyclopentadiene and tricyclodecenone with the catalytic species.
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  • 47
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    Adsorption 6 (2000), S. 137-147 
    ISSN: 1572-8757
    Keywords: adsorption ; kinetics ; linear driving force model ; process design
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The Linear Driving Force (LDF) model for gas adsorption kinetics is frequently and successfully used for analysis of adsorption column dynamic data and for adsorptive process designs because it is simple, analytic, and physically consistent. Yet, there is a substantial difference in the characteristics of isothermal batch uptake curves on adsorbent particles by the LDF and the more rigorous Fickian Diffusion (FD) model. It is demonstrated by using simple model systems that the characteristics of the adsorption kinetics at the single pore or the adsorbent particle level are lost in (a) evaluating overall uptake on a heterogeneous porous solid, (b) calculating breakthrough curves from a packed adsorbent column, and (c) establishing the efficiency of separation by an adsorptive process due to repeated averaging of the base kinetic property. That is why the LDF model works in practice.
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  • 48
    ISSN: 1572-879X
    Keywords: ammonia synthesis ; kinetics ; ruthenium catalysts ; promotional effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetics of NH3 synthesis over carbon-based ruthenium catalysts promoted with barium or alkali was studied. Both the ammonia partial pressure dependencies of the reaction rates (T = 400°C, p = 63 bar, H2 : N2 = 3 : 1) and the pressure variations of the activity (T = 370°C, p= 4–63 bar, H2 : NN2 = 3 : 1) were found to be different for Ba and for the alkali (K, Cs). Ba–Ru/C proved to be more sensitive to the NH3 content and to the total pressure. The rate of synthesis over the alkali-promoted catalysts is, in turn, much stronger influenced by the ruthenium dispersion. TOFs of NH3 synthesis for the promoted samples at 370°C and 4 bar (Ba 0.085 1/s, Cs 0.05 1/s, K 0.035 1/s) are significantly higher than that for the Ru(0001) basal plane (0.0085 1/s results from the literature data at 370°C, 2 bar). The most active Ru/C samples (Ba or Cs) exceed significantly the fused iron catalyst, especially at high conversions.
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  • 49
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    Powder metallurgy and metal ceramics 39 (2000), S. 540-544 
    ISSN: 1573-9066
    Keywords: compaction ; facing ; cumulative charge ; powder ; composite ; heterogeneous structure ; particle ; kinetics ; surface ; die ; model ; xeroradiogram
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract An experimental and numerical (finite element method) study is carried out for the effect of forming scheme on property distribution for cumulative charge facings made from composite heterogeneous powder material. An experimental procedure is developed for studying powder particle flow kinetics. It is shown that use of composite punches and partition of the moulded material into a number of sub-divisions with their successive compaction achieves a more uniform density distribution for an article. It is demonstrated how the direction of the force of friction on the die walls during compaction affects the compaction of articles with faces that are not perpendicular to the direction of the pressing. The results obtained make it possible to select the optimum compaction regime taking account of production features connected with powder material composition as well as service characteristics.
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  • 50
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    Chemistry of heterocyclic compounds 36 (2000), S. 857-861 
    ISSN: 1573-8353
    Keywords: salts of 2,5-dimercapto-1,3,4-thiadiazole ; alkylation ; kinetics ; electronic absorption spectra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A kinetic investigation has been carried out, using electronic absorption spectra, of the alkylation with benzyl chloride of the dihydrazine, monohydrazine, and the disodium salts of 2,5-dimercapto-1,3,4-thiadiazole, and also of the hydrazine and sodium salts of 5-benzylthio-2-mercapto-1,3,4-thiadiazole. The rates orders and constants were established for the benzylation reaction and it was noted that the reaction rate depends on the cation of these salts and the degree of substitution of the 2,5-dimercapto-1,3,4-thiadiazole.
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  • 51
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    Intensive care medicine 26 (2000), S. 942-949 
    ISSN: 1432-1238
    Keywords: Key words Ventilator-associated pneumonia ; Cardiac surgery ; Children ; Pediatric intensive care ; Complications ; Extubation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Objective: This study was undertaken to determine the delay of extubation attributable to ventilator-associated pneumonia (VAP) in comparison to other complications and complexity of surgery after repair of congenital heart lesions in neonates and children.¶Methods: Cohort study in a pediatric intensive care unit of a tertiary referral center. All patients who had cardiac operations during a 22-month period and who survived surgery were eligible (n = 272, median age 1.3 years). Primary outcome was time to successful extubation. Primary variable of interest was VAP. Surgical procedures were classified according to complexity. Cox proportional hazards models were calculated to adjust for confounding. Potential confounders comprised other known risk factors for delayed extubation.¶Results: Median time to extubation was 3 days. VAP occurred in 26 patients (9.6 %). The rate of VAP was not associated with complexity of surgery (P = 0.22), or cardiopulmonary bypass (P = 0.23). The adjusted analysis revealed as further factors associated with delayed extubation: other respiratory complications (n = 28, chylothorax, airway stenosis, diaphragm paresis), prolonged inotropic support (n = 48, 17.6 %), and the need for secondary surgery (n = 51, 18.8 %; e. g., re-operation, secondary closure of thorax). Older age promoted early extubation. The median delay of extubation attributable to VAP was 3.7 days (hazards ratio HR = 0.29, 95 % CI 0.18–0.49), exceeding the effect size of secondary surgery (HR = 0.48) and other respiratory complications (HR = 0.50).¶Conclusion: VAP accounts for a major delay of extubation in pediatric cardiac surgery.
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  • 52
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    Trauma und Berufskrankheit 2 (2000), S. S136 
    ISSN: 1436-6274
    Keywords: Schlüsselwörter ; Vordere Kreuzbandverletzung ; Kinder ; Rekonstruktion ; Indikation ; Key words ; ACL lesion ; Children ; Reconstruction ; Indications
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract For ACL lesions in children near to the end of the growth phase the treatment can be treated identical to that in adults. For younger children (8–12 years) the treatment must be conservative, combined with controls at short intervals. Behaviour during sport should be modified. If instability is experienced in activities of daily life or during sport a reconstruction of the ACL should be done using a central tibial transepiphyseal hamstring reconstruction with a femoral over-the-top position to avoid possible growth disturbances.
    Notes: Zusammenfassung Kreuzbandverletzungen bei Kindern, die nahe ihres Wachstumsabschlusses sind (14. bis 17. Lebensjahr) können wie Kreuzbandverletzungen von Erwachsenen behandelt werden. Kreuzbandverletzungen bei Kindern, die 13 Jahre und jünger sind, sollten zunächst abwartend behandelt werden (Kniebandage, Koordinationstraining, Belastungsreduzierung). Stellt sich im täglichen Leben oder bei sportlicher Belastung eine Instabilität im Sinne eines Giving way heraus, so sollte das Kreuzband rekonstruiert werden. Dabei ist es nach allen vorliegenden Daten unbedenklich, die Tibia zentral mit einem 8-mm-Bohrloch zu durchbohren und ein ligamentäres Transplantat durchzuziehen. Femoral ist es aus Sicherheitsgründen eher sinnvoll, statt einer transossären Bohrung die Over-the-top-Position zu wählen. Auch andere, rein epiphysäre Verankerungsmethoden (Semitendinosusplastik mit transossärer Drahtfixation) sind möglich.
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  • 53
    ISSN: 1439-0973
    Keywords: Key Words Ritonavir ; Nelfinavir ; Children ; Antiretroviral agents ; HIV-1
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Background: Knowledge concerning the long-term antiretriviral and immunological efficacy of protease inhibitors in children is limited. Patients and Methods: An open-label, prospective, multicenter clinical trial was conducted over a period of 72 weeks in Switzerland. 60 HIV-1 infected children (aged 0.3–16.9 years) naive to protease inhibitors were enrolled. Ritonavir or nelfinavir and at least one new nucleoside reverse transcriptase inhibitor were introduced into the durrent treatment regimen. HIV-1 RNA levels and CD4 cell counts were monitored after introducing the protease inhibitor, and the tolerability and safety of the drugs were assessed. Results: Dictated by chronological availability, 37 children received ritonavir and 23 nelfinavir. At baseline, children given ritonavir had higher mean plasma HIV-1 RNA levels (5.03 vs 4.63 log10 copies/ml; p = 0.001) and lower mean CD4 cell counts (277 vs 555 cells/μl; p = 0.009) than children given nelfinavir. Antiretroviral treatment (ART) naive children showed higher mean plasma HIV-1 RNA levels than non-naive (5.18 vs 4.64 log10 copies/ml; p = 0.02). The decline in plasma HIV-1 RNA levels 72 weeks after treatment with ritonavir and nelfinavir was −2.17 and −1.30 log10 copies/ml, respectively (p = 0.006) and in ART-naive vs non-naive patietns −2.70 vs − 1.39 log10 copies/ml (p ≤ 0.01). 69% of ART-naive patients and 32% of non-naive patients achieved sustained plasma HIV-1 RNA levels 〈 400 copies/ml. Increases in CD4 cells were higher in ART naive compared to non-naive patients (p 〈 0.04). Conclusion: The antiretroviral and immunologic benefits of protease inhibitors are more profound in ART-naive than in non-naive children.
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  • 54
    ISSN: 1439-0973
    Keywords: Key words Tick-borne encephalitis ; Children ; Adults
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The aim of this prospective study was to compare epidemiological data and clinical features in children and adults with tick-borne encephalitis (TBE). Patients with aseptic meningitis diagnosed at the University Medical Centre, Department of Infectious Diseases, Ljubljana, Slovenia, from June to August 1997, in whom the diagnosis of TBE was ascertained by the presence of serum IgM antibodies against TBE virus, who were serologically negative for Borrelia burgdorferi sensu lato and had a negative PCR CSF result on enteroviral infection, were included in the study. Out of 213 patients with aseptic meningitis, 80 (37–56%) fulfilled inclusion criteria. There were 20 children and 60 adults. In both groups males predominated. Virtually all patients had headache and fever, and more than 50% suffered from vomiting. The majority of patients in both groups recalled a tick bite, had a biphasic course of the illness, and was found to have obviously expressed meningeal signs. In both groups the median CSF leukocyte count was somewhat lower than 100 × 106/l with a predominance of lymphocytes. Children were more often given antibiotics during the initial phase of TBE than adults (p = 0.0095). Several other statistically significant distinctions (p 〈 0.05) were found including the frequency of fatigue, malaise, vertigo, photophobia, myalgias, arthralgias, as well as elevated CSF albumin and protein concentration, elevated albumin quotient and IgG quotients; all these findings were more often present in adults. In addition a longer duration of fever, more frequent need for anti-edematous treatment and longer hospitalization were found in adults. Direct comparison of clinical and epidemiological characteristics of TBE in children and adults revealed differences in several clinical and laboratory features and corroborates the previous conclusion that TBE in childhood is a milder illness than TBE in adults.
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  • 55
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    Journal of urban health 77 (2000), S. 723-734 
    ISSN: 1468-2869
    Keywords: Child welfare ; Children ; Disclosure ; HIV ; Mothers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The purpose of this investigation was to ascertain the reasons given by mothers diagnosed with AIDS (acquired immunodeficiency syndrome) for disclosing or not disclosing their HIV (human immunodeficiency virus) status to their children, a dilemma faced by most HIV-infected parents and those who counsel them. We interviewed 29 mothers residing in one of two New York City facilities that provide housing and medical treatment for adults with AIDS. The majority of these mothers do not live with their children, but all had recent face-to-face contact with them. The two reasons most frequently considered important for disclosing to children were that disclosure was the “right thing to do” and the need to make arrangements for children's future in case of maternal death or incapacity. The reason most frequently considered important for not disclosing was maternal concern about discussing death and dying with children. These findings have significant implications for counseling of HIV-positive parents.
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  • 56
    ISSN: 1439-0973
    Keywords: Key words Pertussis ; Bordetella pertussis ; Hospitalization ; Complications ; Vaccine ; Children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We prospectively followed 725 children under 2 years of age with laboratory-diagnosed Bordetella pertussis infection to investigate the hospitalization rate and complications. Diagnosis was made by culture and polymerase chain reaction (PCR) from nasopharyngeal swabs in 11,016 children who presented with ≥ 7 days of cough at 63 pediatric practices in Germany. Of these children, 33 (4.5%) were hospitalized at a mean age of 4.8 months (range, 17 days to 19.5 months). Complications occurred in 16 (48%) of the 33 patients. Pneumonia developed in two (6%) children and a convulsion was observed in one (3%). Intensive care monitoring was required for 23 (70%) children. Further complications were bradycardia (21%), apnea (12%), conjunctivitis (12%), loss of weight (12%), otitis media (6%), atelectasis (3%) and dehydration (3%). Children aged 6–24 months who had not received any dose of pertussis vaccine had a ten-fold increased risk of hospitalization compared to those who had been partially or fully immunized (p 〈 0.05). Pertussis immunization should be given at an early point in time and completely in order to prevent severe courses of pertussis and hospitalization in young children.
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  • 57
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    Infection 28 (2000), S. 282-286 
    ISSN: 1439-0973
    Keywords: Key Words Chronic ; Osteomyelitis ; Therapy ; Children ; Ewing's sarcoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Background: Presently, most children with chronic osteomyelitis undergo surgery with the inherent risk of damage to their growth plate. We demonstrate a treatment regimen based on imaging procedures focussing on antibiotics in order to reduce the rate of surgical interventions. Patients and Methods: We retrospectively evaluated all 11 patients with clinically suspected chronic osteomyelitis who were treated at our institution from 1989 to 1995. Patients underwent open biopsy and surgical treatment only if imaging procedures showed signs indistinguishable from malignancy, or if they were highly suggestive for the presence of pus, joint infection or osteonecrosis. The patients were followed up for a minimum of 3 years. Results: All five patients treated solely with antibiotics recovered completely. Three patients were subjected to open biopsy and surgical treatment since they showed radiological signs indistinguishable from malignancy, and two patients due to pus or osteonecrosis. In follow-up, there was one relapse of chronic osteomyelitis 11 months after the first treatment course with surgery and antibiotics. One patient suffering from Ewing's sarcoma as detected by open biopsy was excluded. Conclusion: Our diagnostic procedure was useful to reduce the rate of surgery. Surgical treatment of chronic osteomyelitis is not always neccessary especially in cases of missing necrosis, joint infection and abscess as demonstrated by the complete recovery of our patients treated solely with antibiotics.
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  • 58
    ISSN: 1573-515X
    Keywords: gaseous ; kinetics ; mercury ; methods ; speciation ; waters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Mercury evasion from water is commonly modeled using measurements of dissolved gaseous mercury (DGM). We developed a method using a recently available automated field-ready mercury vapor analyzer to rapidly measure the concentrations of DGM in surface waters. We summarize here results of laboratory tests of the method, field intercomparisons with a manual method, and selected data from recent sampling campaigns in Florida and Michigan. The method uses the 1.5 lpm flow of a Tekran® Model 2537A mercury analyzer to purge and analyze discrete water samples, generating near real time (5-min) data on DGM in samples and blanks. Application of the Tekran allowed for detailed analysis of DGM removal kinetics and short-term diel studies characterizing the influence of sunlight and precipitation on DGM production in surface waters. Gas removal kinetics for dozens of samples indicates a first-order rate constant, and supports a 20-min. purge time for surface water samples from Florida (40-min for Michigan samples). Blanks are measured during a second such purge. Our results indicate that DGMs determined by both automated and manual methods are generally comparable, and that DGM in Florida samples is unstable during storage (loss rate constant ∼0.1--0.2 h-1), probably due to oxidation. This suggests that rapid in-field analysis is preferred to storage with delayed analysis. Our data indicate that DGM at the Florida site is influenced by inputs of reactive Hg in rainwater, and by production of surface DGM during photoreduction of oxidized Hg in the water column.
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  • 59
    ISSN: 1573-6881
    Keywords: Permeability transition ; ADP/ATP translocase ; kinetics ; adenosine diphosphate ; carboxya tractyloside ; bongkekic acid ; mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Low levels of ADP binding at the ADP/ATP translocase caused inhibition of the Ca2+-inducedpermeability transition of the mitochondrial inner membrane, when measured using the shrinkage assay on mitochondria, which have already undergone a transition. Inhibition was preventedby carboxyatractyloside, but potentiated by bongkrekic acid, which increased the affinity forinhibition by ADP. This suggests that inhibition was related to the conformation of thetranslocase. Ca2+ addition was calculated to remove most of the free ADP. Ca2+ added after ADPinduced a slow decay of the inhibition, which probably reflected the dissociation of ADP fromthe translocator. We conclude that the probability of forming a permeability transition pore(PTP) is much greater when the translocase is in the CAT conformation than in the BKAconformation, and, in the absence of CAT and BKA, the translocator is shifted between theBKA and CAT conformations by ADP binding and removal, even in deenergized mitochondria with no nucleotide gradients.
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  • 60
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    Pharmaceutical research 17 (2000), S. 701-706 
    ISSN: 1573-904X
    Keywords: vapor sorption ; molar heat of adsorption ; kinetics ; isothermal microcalorimetry ; recrystallization ; hydration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. In this study, instrumentation for measuring vapor sorptionenthalpies and sorption uptakes simultaneously with an isothermalmicrocalorimeter is introduced. Various pharmaceutical modelsubstances undergoing phase transitions when exposed to humid conditions(25°C), were employed to evaluate the usefulness and sensitivity ofthe constructed experimental method. Methods. The sample is placed in the sample vessel of a RH cell andthe moisture content of the air flow is controlled. From the RH cellthe air flow is conducted into a subsequent perfusion cell in which asaturated salt solution has been loaded. The RH cell and perfusioncells are positioned in the sample sides of two twin calorimetric units.Depending on the moisture content in the outlet flow leaving thepreceding RH cell, the heat flow signal from the subsequent perfusioncell will vary. By means of blank measurement with identical settings,the rate of water sorption can be calculated and, by integration, theamount of sorbed water is obtained. Results. Amorphous lactose and cefadroxil undergo recrystallizationwhen the moisture level in the surroundings exceeds the thresholdvalues specific to each compound. During the sorption phase, heat isevolved fairly linearly as a function of consumed moisture, and alsoafter the recrystallization, the heats indicate linear behavior. The heatvalues for the desorption phase of amorphous lactose and the adsorptionof crystalline lactose coincide. With the different anhydrous forms oftheophylline, the hydration takes place more rapidly in the metastableform I, and generally, the process is more energetic in form I. In allcases, the gravimetric results agree with the water sorption uptakescalculated from the calorimetric data. Conclusions. The technique introduced offers a rapid and sensitivemethod to gain new insights into the transitions in which vapors areinvolved. In addition, different kinds of surfaces with various energeticscan now be studied more closely.
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  • 61
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    Reaction kinetics and catalysis letters 69 (2000), S. 169-176 
    ISSN: 1588-2837
    Keywords: Al3+-exchanged pillared clay catalyst ; 2-methoxyethanol ; esterification ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The pillared clay catalyst, which was obtained by exposing activated clay powder to sulfuric acid and aluminium salts and calcining in air at 373 – 673 K, was found to be highly active for the title reaction. The activity is mainly attributed to the Lewis acid sites and also to a small number of Brönsted acid sites, whose number and strength increases with the extent of pillaring. The kinetic equation of surface esterification is y = 2.57x - 1.47.
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  • 62
    ISSN: 1588-2837
    Keywords: Dichlorocyclopropanation ; 4-vinyl-1-cyclohexene ; phase transfer catalysis ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetics of regioselective dichlorocyclopropanation of 4-vinyl-1-cyclohexene has been studied under controlled phase transfer catalysis conditions, using aqueous sodium hydroxide as the base and 2-benzylidine-N,N,N,N′,N′,N′-hexaethylpropane-1,3-diammonium dibromide (Dq-Br) as a new phase transfer reagent. The reaction was carried out at 40 °C under pseudo-first order conditions by employing aqueous sodium hydroxide and chloroform in excess and was monitored by gas chromatography. The effect of various experimental parameters on the rate of the reaction has been studied and based on the experimental results, a suitable mechanism is proposed.
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  • 63
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    Reaction kinetics and catalysis letters 70 (2000), S. 119-124 
    ISSN: 1588-2837
    Keywords: Tenoxicam ; photodegradation ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Photodegradation of tenoxicam was investigated under different reaction conditions. After 60 min of exposure to UV light, the photodegradation was extensive, and the maximum and minimum in the UV-visible spectrum were shifted to shorter and longer wavelengths, respectively. Ethanol exerted a photostabilizing effect on tenoxicam. Tenoxicam is more stable in acidic and basic media than in neutral solution. Increasing light intensity or temperature causes an increase in the rate of photodegradation. The photodegradation of tenoxicam was found to follow first-order kinetics under all these conditions.
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  • 64
    ISSN: 1588-2837
    Keywords: Ferrites ; aniline alkylation ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Kinetic parameters such as the activation energy (Ea) and Arrhenius frequency factor (A) for the N-methylation of aniline using methanol over Zn-Co ferrites have been calculated. The Ea value is found to be lower than the existing best alkylating systems such as γ-alumina and magnesium oxide.
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  • 65
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    Reaction kinetics and catalysis letters 70 (2000), S. 235-241 
    ISSN: 1588-2837
    Keywords: Methanol ; isobutanol ; ethers ; γ-Al2O3 ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetic of methanol (MeOH) and isobutanol (iBuOH) coupling to ethers has been studied. Catalytic tests were carried out in the gas phase in a fixed-bed flow microreactor, in the temperature range of 463-533 K, under atmospheric pressure, using γ-Al2O3 as the catalyst. The quasi-homogeneous model for the process was assumed. The reaction rates were described by simple kinetics.
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  • 66
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    Reaction kinetics and catalysis letters 71 (2000), S. 295-300 
    ISSN: 1588-2837
    Keywords: Sintering ; kinetics ; Pt/Al2O3
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The variation of dispersion of Pt on Al2O3 support with sintering time is measured and the value of equilibrium dispersion of Pt is obtained directly. It is found that a General Power Law Expression can fit the experimental data well.
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  • 67
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    Reaction kinetics and catalysis letters 69 (2000), S. 247-252 
    ISSN: 1588-2837
    Keywords: Phosphorous acid ; oxidation ; kinetics ; mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The oxidation of lower phosphorus oxyacids by benzyltrimethylammonium chlorobromate (BTMACB) proceeds by a mechanism involving a hydride-ion transfer from oxyacids to the oxidant in the rate-determining step.
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  • 68
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    Reaction kinetics and catalysis letters 70 (2000), S. 139-145 
    ISSN: 1588-2837
    Keywords: Oxidation of sulfides ; kinetics ; Ni-oxide system ; reaction mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Catalytic oxidation of sulfide ions in aqueous solutions by air oxygen has been investigated using a Ni-oxide system as a catalyst. The kinetics and the selectivity of the oxidation process were studied by varying the pH, catalyst amount and reaction temperature. A reduction/oxidation mechanism of the reaction has been supposed comprising interaction between the surface active oxygen of the catalyst and HS− and reoxidizing of the reduced catalyst by the dissolved oxygen. The results obtained show that the Ni-oxide system is a promising catalyst for practical application.
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  • 69
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    Reaction kinetics and catalysis letters 70 (2000), S. 319-324 
    ISSN: 1588-2837
    Keywords: Atmospheric chemistry ; kinetics ; OH-radical ; CH2F2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The rate constant value of k 1 = (6.05 ± 0.20)×109 cm3 mol−1 s−1 (with ± 1σ error) has been determined for the reaction OH + CH2F2 (1) by applying the discharge-flow/resonance-fluorescence method at 298 K.
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  • 70
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    Reaction kinetics and catalysis letters 71 (2000), S. 47-54 
    ISSN: 1588-2837
    Keywords: Alkylbenzenes ; hydrogenation ; nickel ; kinetics ; stereochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Experimental data on gas-phase hydrogenation of several alkylbenzenes (toluene, ethlylbenzene, o-, m-, p-xylenes, mesitylene) over nickel catalyst are summarized. Rate dependence as a function of the chemical nature of substituent and position in the aromatic ring is discussed. The stereochemical distribution for dialkylbenzene and trialkylbenzene is addressed.
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  • 71
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    Reaction kinetics and catalysis letters 70 (2000), S. 147-151 
    ISSN: 1588-2837
    Keywords: Oxo-functionalization ; [RuIII(amp)(pic)(H2O)] ; t-BuOOH ; kinetics ; cyclohexane cyclohexene ; toluene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A novel mixed-ligand [RuIII(amp)(pic)(H2O)] complex (1) (H2amp = N-(hydroxyphenyl)salicyldimine; pic = picolinate) has been synthesized and characterized by physico-chemical methods. Complex 1has been found to be an effective catalyst in oxo-functionalization of C-H bond of organic substrates by using tert-butyl hydroperoxide (t-BuOOH) as a terminal oxidant. Formation of a high valent Ru(V)-oxo species as catalytic intermediate is proposed to be the source of oxygen atom in the oxidised product.
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  • 72
    ISSN: 1588-2837
    Keywords: Fe(CN)5(4-tbupy)3- ; kinetics ; electrolytes ; substitution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The ligand substitution reaction [Fe(CN)5(4-tbupy)]3- + pyrazine (4-tbupy=4-tertbutylpyridine) was studied in aqueous concentrated electrolyte solutions at 298 K. Plots of ln(k/kw) against (γ-γw), where the subscript w refers to pure water and γ is the surface tension of the appropriate salt solution, gave a common straight line for all the electrolytes studied and permits to estimate the activation volume.
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  • 73
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    Reaction kinetics and catalysis letters 71 (2000), S. 343-347 
    ISSN: 1588-2837
    Keywords: Deoximination ; chromium (VI) ; kinetics ; mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Oxidative deoximination of aldoximes and ketoximes by pyridium fluorochromate proceeds by nucleophilic attack of the chromate oxygen on the oxime carbon to give a cyclic intermediate in the rate-determining step.
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  • 74
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    Reaction kinetics and catalysis letters 69 (2000), S. 39-46 
    ISSN: 1588-2837
    Keywords: Coke formation ; kinetics ; USHY zeolites ; ethene ; propene ; 1-butene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A simplified three-parameter model for the interpretation of the kinetic data of coke formation during transformation of light olefins is presented. This model has been applied to the transformation of ethene, propene and 1-butene over fresh and regenerated zeolite USHY at 623 K. The proposed model covers both the coverage of the acid sites and the autocatalytic growth of coke.
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  • 75
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    Topics in catalysis 11-12 (2000), S. 327-333 
    ISSN: 1572-9028
    Keywords: hydrodenitrogenation ; toluidine ; methylcyclohexylamine ; kinetics ; nickel-promoted molybdenum sulphide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The hydrodenitrogenation (HDN) of o-toluidine and its reaction intermediates was studied over a NiMo/γ-Al2O3 catalyst. The kinetics of the HDN of methylcyclohexylamine and of the hydrogenation of cyclohexene were also studied. Hydrogenation of o-toluidine alone produces methylcyclohexene and methylcyclohexane. When a sufficient quantity of cyclohexene is added during the HDN of toluidine, methylcyclohexylamine, the first intermediate in the hydrogenation of toluidine, becomes detectable. Because of its strong adsorption constant and high rate constant for reacting further to methylcyclohexene and methylcyclohexane, methylcyclohexylamine is not observed in the HDN of toluidine. Adding cyclohexene decreases the adsorption of methylcyclohexylamine, thus enabling its detection. The rate and adsorption constants of methylcyclohexylamine and cyclohexene in the HDN of methylcyclohexylamine were calculated by fitting the kinetic data to a Langmuir–Hinshelwood equation. A two-site model was used to describe the surface reactions, with one site for the methylcyclohexylamine reactions and the other for the cyclohexene reaction.
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    Journal of thermal analysis and calorimetry 59 (2000), S. 633-642 
    ISSN: 1572-8943
    Keywords: cadmium ; dialkyldithiocarbamate ; kinetics ; thermal decomposition ; thermogravimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The thermal decomposition kinetics of the solid complexes Cd(S2 CNR2 )2 , where R =C2 H5 , n -C3 H7 , n -C4 H9 or iso -C4 H9 , was studied by using isothermal and non-isothermal thermogravimetry. The superimposed TG/DTG/DSC curves revealed that thermal decomposition reactions occur in the liquid phase. The kinetic model that best fitted the experimental isothermal TG data was the one-dimensional phase-boundary reaction-controlled process R1 . The thermal analysis data suggested the thermal stability sequence Cd(S2 CNBun 2 )2 〉Cd(S2 CNPrn 2 )2 〉Cd(S2 CNBui 2 )2 〉Cd(S2 CNEt2 )2 , which accords with the sequence of stability of the apparent activation energies.
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  • 77
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    Journal of thermal analysis and calorimetry 61 (2000), S. 979-984 
    ISSN: 1572-8943
    Keywords: kinetics ; nucleation-growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The author presents some applications of the fractal geometry in the kinetics of heterogeneous decomposition of solids.
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  • 78
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    Journal of thermal analysis and calorimetry 59 (2000), S. 935-942 
    ISSN: 1572-8943
    Keywords: CoSO46H2O ; kinetics ; thermal decomposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Thermogravimetry (TG-DTG), and differential thermal analysis (DTA) were used in the study of the kinetics of decomposition of cobalt sulphate hexahydrate under an air atmosphere. The kinetics of the particular stages of CoSO4 6H2 O decomposition were evaluated from the dynamic mass loss data. The values of the kinetic parameters for each stage of the thermal decomposition were calculated from the α(T) data by using the integral method, applying the Coats-Redfern approximation.
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  • 79
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    Journal of thermal analysis and calorimetry 63 (2000), S. 397-413 
    ISSN: 1572-8943
    Keywords: Cu–5 at%Zn ; DSC ; F.C.C. (Face Centered Cubic) ; kinetics ; short-range-order ; solute-vacancy complexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A modified first order kinetic law, which describes the roles of bound and unbound vacancies, is proposed in order to predict defect decay and short-range-order kinetics of quenched binary alloys during linear heating experiments. The model has been applied to differential scanning calorimetry (DSC) curves of Cu–5 at%Zn quenched from different temperatures. Activation energy for migration of solute-vacancy complexes was also assessed from the kinetics of short-range-order using DSC traces. A value of 89.5±0.32 kJ mol–1 was obtained. The relative contribution of bound and unbound vacancies to the ordering process as influenced by quenching temperature was determined. In conjunction, a parametric study of the initial total defect concentration and effective energy for defect migration was performed in order to envisage their influence on the calculated DSC profiles.
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  • 80
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    Journal of thermal analysis and calorimetry 63 (2000), S. 457-463 
    ISSN: 1572-8943
    Keywords: isoconversional methods ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract It is demonstrated that, if the activation energy depends on the degree of conversion, its values obtained by isoconversional differential and integral methods are different.
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  • 81
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    Journal of thermal analysis and calorimetry 61 (2000), S. 861-871 
    ISSN: 1572-8943
    Keywords: DAGN ; kinetics ; mechanism and IR spectroscopy ; TAGN ; thermal decomposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Diaminoguanidine nitrate (DAGN) and triaminoguanidine nitrate (TAGN),potential energetic materials in emerging propulsion technology with high mass impetus at low isochoric flame temperature have been studied as regards kinetics and mechanism of thermal decomposition using thermogravimetry (TG), differential thermal analysis (DTA),infrared spectroscopy (IR) and hot stage microscopy. Kinetics of thermolysis has been followed by isothermal TG and IR. For the initial stage of thermolysis of DAGN the best linearity with a correlation coefficient of 0.9976 was obtained for the Avrami-Erofe'evequation, n=2, by isothermal TG. The activation energy was found to be 130 kJ mol–1 and logA=11.4. The initial stage of thermolysis of TAGN also obeyed the Avrami-Erofe'ev equation, n=2, with a correlation coefficient of 0.9975by isothermal TG and the kinetic parameters are E=160.0 kJ mol–1 and logA=16.0. High temperature IR spectra showed exquisite preferential loss in intensity of the NH2, NH, N–N stretching and CNN bending. Spectroscopic and other results favour deamination reaction involving the rupture of the N–N bond as the primary step in the thermal decomposition.
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  • 82
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    Journal of thermal analysis and calorimetry 62 (2000), S. 681-685 
    ISSN: 1572-8943
    Keywords: coal-burning additive ; combustion ; graphite ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The catalytic and accelerating effects of three coal-burning additives (CBA) on the burning of graphite were studied with the help of thermogravimetric (TG) analysis. The kinetic study on the catalytic oxidation of the graphite doped with CBA was carried out and the results were presented. The results show that the CBA can change the carbon oxidation/combustion course by catalytic action and change the activation energy, thus improving the combustion efficiency.
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  • 83
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    Journal of thermal analysis and calorimetry 63 (2000), S. 375-386 
    ISSN: 1572-8943
    Keywords: activation energy ; ammonium perchlorate ; decompositon ; isothermal ; kinetics ; thermogravimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetics of the thermal decomposition of ammonium perchlorate at temperatures between 215 and 260°C is studied, in this work, by measuring the sample mass loss as a function of time applying the isothermal thermogravimetric method. From the maximum decomposition rate – temperature dependence two different decomposition stages, corresponding to two different structural phases of ammonium perchlorate, are identified. For the first region (215–235°C), corresponding to the orthorhombic phase, the mean value of the activation energy of 146.3 kJ mol–1, and the pre-exponential factor of 3.43⋅1014 min–1 are obtained, whereas for the second region (240–260°C), corresponding to the cubic phase, the mean value of the activation energy of153.3 kJ mol–1, and the pre-exponential factor of 4.11⋅1014 min–1 are obtained.
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  • 84
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    Journal of thermal analysis and calorimetry 60 (2000), S. 25-33 
    ISSN: 1572-8943
    Keywords: DSC ; kinetics ; thermal decomposition ; 2,4,6-trinitrotoluene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An autocatalytic model involving the limited solubility of volatile catalytic products was applied to the thermal decomposition of 2,4,6-trinitrotoluene. The critical supersaturation of the thermal decomposition products with the catalytic properties was higher at a low heating rate. Decrease of the sample mass led to an increased critical supersaturation of the decomposition products. This is probably a result of the greater contribution of products adsorption on the aluminium pan surface. It is presumed that the differences observed in the rate constant are connected with the uncontrolled critical supersaturation of the volatile thermal decomposition products.
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  • 85
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    Journal of thermal analysis and calorimetry 60 (2000), S. 35-43 
    ISSN: 1572-8943
    Keywords: kinetics ; 10-methylacridinium halides ; thermodynamics ; thermogravimetric investigations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract 10-Methylacridinium chloride, bromide and iodide were prepared in crystalline forms (the first two salts as monohydrates) and subjected to thermogravimetric investigations. Decomposition of the compounds is initially accompanied by the liberation of water (in case of monohydrates), halomethanes and acridine molecules. As decomposition proceeds, side reactions occur which are reflected in a complex pattern of thermogravimetric curves. TG traces corresponding to the initial decomposition stage were used to determine the kinetic characteristics of the thermal dissociation of the salts. MNDO/d, AM1 and PM3 methods were employed independently to examine reaction pathways and to predict thermodynamic and kinetic barriers for the thermal decomposition of the compounds. These data were subsequently supplemented with theoretically determined crystal lattice energies, which enabled the relevant characteristics for the decomposition of crystalline phases to be predicted. The theoretically predicted characteristics are qualitatively comparable with those originating from thermogravimetric investigations, which allows one to believe that both are valid.
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  • 86
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    Keywords: cyanazine ; DSC ; kinetics ; thermal stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Cyanazine was taken as an example for investigations under the influence of different conditions on thermal decomposition of triazine herbicides. DSC measurements were carried out under atmospheric pressure and hermetically closed, under pressure 1.3 kPa. The influence of the pressure on the constant reaction rate of decomposition of cyanazine was discussed. It was also proved that the predicted reaction constant rates from isothermal and non-isothermal measurements are consistent.
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  • 87
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    Journal of thermal analysis and calorimetry 60 (2000), S. 247-255 
    ISSN: 1572-8943
    Keywords: desulfuration ; gas atmosphere ; kinetics ; thermal decomposition ; titanium dioxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The studies were devoted to determination of the effect of gas atmosphere and its pressure on the second step of decomposition of hydrated titanium dioxide (HTD) promoted by sulfate groups. It has been found that thermal decomposition of HTD at temperatures above 300°C consists of a number of processes such as dehydroxylation, desulfuration, recrystallization and sintering of solid grains, photochemical processes (if the decomposition proceeds in the presence of light) and adsorption of gas phase components (in the presence of air or SO2). Kinetic parameters characterizing this step of decomposition have been determined for processes carried out in vacuum and in argon or air atmospheres (at a pressure of 13.33hPa). The kinetic curves of decomposition carried out in the presence of gases capable of being adsorbed on the surface of partly dehydrated HTD are featured by local extrema due to simultaneous processes of decomposition and adsorption of gas components.
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  • 88
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    Journal of thermal analysis and calorimetry 60 (2000), S. 9-15 
    ISSN: 1572-8943
    Keywords: coordination compounds ; kinetics ; thermal dissociation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Physicalo-chemical importance of the quantitative study of kineticliability of coordination compounds in thermal dissociation processes is considered. Muchattention is given to the proof of the physicalo-chemical meaning and validity of kineticparameters calculated from thermoanalytical data. Experimental data (thermal dissociation ofcoordination compounds and clathrates with such a matrix) are discussed.
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  • 89
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    Journal of thermal analysis and calorimetry 60 (2000), S. 401-407 
    ISSN: 1572-8943
    Keywords: cross-linking ; isothermal crystallization ; kinetics ; modification ; polypropylene ; silica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The effect of addition of silica on the parameters of isothermal crystallization of polypropylene has been investigated. It was found that the covering of the silica surface by a layer of low-density polyethylene leads to a deactivation of the filler regarding the positive effect on the polypropylene crystallization rate parameters. Cross-linking of the surface polyethylene layer results in a stronger attachment of the modifying polymer to the filler surface and the deactivation effect of the silica surface modification is more pronounced.
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  • 90
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    Journal of thermal analysis and calorimetry 60 (2000), S. 541-547 
    ISSN: 1572-8943
    Keywords: Cr(II) ; chromium trioxide ; kinetics ; reduction ; thermal analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The thermal behaviour of CrO3 on heating up to 600°C in dynamic atmospheres of air, N2 and H2 was examined by thermogravimetry (TG), differential thermal analysis (DTA), IR spectroscopy and diffuse reflectance spectroscopy (DRS). The results revealed three major thermal events, depending to different extents on the surrounding atmosphere: (i) melting of CrO3 near 215°C (independent of the atmosphere), (ii) decomposition into Cr2(CrO4)3 at 340–360°C (insignificantly dependent), and (iii) decomposition of the chromate into Cr2O3 at 415–490°C (significantly dependent). The decomposition CrO3 → Cr2(CrO4)3 is largely thermal and involves exothermic deoxygenation and polymerization reactions, whereas the decomposition Cr2(CrO4)3 → Cr2O3 involves endothermic reductive deoxygenation reactions in air (or N2) which are greatly accelerated and rendered exothermic in the presence of H2. TG measurements as a function of heating rate (2–50°C min−1) demonstrated the acceleratory role of H2, which extended to the formation of Cr(II) species. This could sustain a mechanism whereby H2 molecules are considered to chemisorb dissociatively, and then spillover to induce the reduction. DTA measurements as a function of the heating rate (2–50°C min−1) helped in the derivation of non-isothermal kinetic parameters strongly supportive of the mechanism envisaged.
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  • 91
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    Journal of thermal analysis and calorimetry 60 (2000), S. 667-674 
    ISSN: 1572-8943
    Keywords: accommodation function ; crystal growth ; glass-ceramics ; kinetics ; number of nuclei ; thermal history
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Kinetic modeling of the crystal growth from pre-existing nuclei was reexamined to obtain a fundamental information about the controlled crystallization of glasses during formation of advanced inorganic glass-ceramics. Methods of kinetic analysis were reviewed by taking account of thermal history of the sample within the temperature range of nucleation. An accommodation function depending on the thermal history was introduced in the kinetic equation. The role of the accommodation function was reinvestigated when determining the activation energy from a series of kinetic curves. The kinetic description of the crystal growth in the samples with different thermal history was generalized by extrapolating the rate behavior to infinite temperature.
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  • 92
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    Journal of thermal analysis and calorimetry 60 (2000), S. 333-343 
    ISSN: 1572-8943
    Keywords: base line ; DSC ; kinetics ; modeling ; thermodynamics ; TMDSC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The application of non-linear heating program to a heat-flux DSC apparatus has attracted much attention. From thermodynamics viewpoint, it is shown that the variation of enthalpy of a sample changing with temperature change is due, to both the true heat capacity of the sample and the enthalpy of some transformations occurring in the sample, characterized by its degree of advance. Using the simple assumption that the rate of the transformation is proportional to the distance from the thermodynamic equilibrium, an electrical model of the thermal event is given. Using the coupled cell model of the DSC apparatus, we show how to obtain the rate of transformation of the sample and heat capacity, which is directly related to the base line of the experiment.
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  • 93
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    Journal of thermal analysis and calorimetry 60 (2000), S. 759-778 
    ISSN: 1572-8943
    Keywords: decomposition temperature ; error sources ; gas-flow and vapor control ; kinetics ; thermogravimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The well-known divergence between the present ‘state of the art’ of thermogravimetry and industrial requirements is discussed. Sources of errors are analyzed and the optimization of measuring conditions is discussed regarding the problems associated with static and dynamic (flow) atmospheres, and interactions between materials and gases or vapors. Recommendations for gas-flow control systems and vapor sources are given. Thermal stability and the kinetics of gas-evolving, reversible, thermal decompositions of solids are discussed. The scope of TG-derived kinetics for practical use is examined. Some new characteristic points of TG curves are proposed and defined, e.g. ‘procedure-independent decomposition temperature’ and ‘augmented decomposition temperature’ (obtained at pseudo-equilibrium conditions).
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  • 94
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    Journal of thermal analysis and calorimetry 60 (2000), S. 879-886 
    ISSN: 1572-8943
    Keywords: driving force ; kinetics ; rate equation ; reversible reactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract This paper outlines the different ways of taking the distance from thermodynamic equilibrium into account in kinetic studies based on thermoanalytical experiments. The three main approaches are: (i) avoiding or neglecting the effect of the reverse reaction, (ii) describing the influence of distance from equilibrium on apparent kinetic parameters, and (iii) incorporating a driving force factor in the rate equation. Finally, the contradiction of the microscopic nature of the processes and the macroscopic character of the usual rate equation are briefly discussed.
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  • 95
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    Journal of thermal analysis and calorimetry 60 (2000), S. 943-954 
    ISSN: 1572-8943
    Keywords: CRTA ; kinetics ; self-generated atmospheric conditions ; synthetic malachite ; thermal decomposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetic behavior of the thermal decomposition of synthetic malachite was investigated by means of CRTA under different conditions of reduced pressure, flowing gases and quasi-isobaric atmospheres. The thermal decomposition was found to proceed at lower temperatures under the influence of the self-generated gases, CO2 and H2O. From a viewpoint of chemical equilibrium, the normal and opposite effects on the overall kinetics were observed for the self-generated CO2 and H2O, respectively. The complexity of the present reaction is also reflected by the variations of the apparent kinetic parameters which depend on the applied and self-generated atmospheric conditions. The practical usefulness of CRTA when applied to a complicated thermal decomposition is discussed as exemplified by the kinetic approaches to the present reaction.
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  • 96
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    Journal of thermal analysis and calorimetry 61 (2000), S. 151-156 
    ISSN: 1572-8943
    Keywords: complexes ; kinetics ; TG-DTA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Thermal behaviour of a few lanthanide complexes of the type ML3(I) [M=Eu,Gd; HL=4,4,4-trifluoro- 1-(2-napthyl)-1,3-butanedione and EuL30.5dmm dmm=2,6-dimethylmorpholine(II)], has been investigated. From thermogravimetric(TG) curves, the decomposition pattern of the compounds has been analysed on the basis of mass loss data. The order and activation energy of the thermal decomposition reactions have been elucidated. From differential thermal analysis (DTA) studies, the heat of reaction and rate of thermal decomposition reaction have been enumerated.
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  • 97
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    Journal of thermal analysis and calorimetry 61 (2000), S. 239-242 
    ISSN: 1572-8943
    Keywords: kinetics ; Mannich compounds ; thermal decomposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The authors present data concerning the evaluation of kinetic parameters of the decomposition of a Mannich compound by using the classical method of constant heating rate thermal analysis and the new one of controlled rate thermal analysis (CRTA). The data processed using the CRTA method allow to obtain more reliable kinetic parameters according to the proposed reaction mechanism.
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  • 98
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    Journal of thermal analysis and calorimetry 61 (2000), S. 437-450 
    ISSN: 1572-8943
    Keywords: crystallization ; EPDM ; kinetics ; morphology ; PP ; rubber
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The effect of the incorporation of an amorphous immiscible polymer (ethylene-propylene-diene- terpolymer) on the PP crystallization kinetics and thermodynamics is investigated by thermal analysis. The results of the investigation have shown that EPDM acts as a nucleant agent. A marked decrease of the half time of PP crystallization, τ1/2 , as well as a sensible increase of the overall crystallization rate, K n , has been observed in the presence of EPDM. Moreover, at any crystallization temperature, a minimum of τ1/2 , is obtained at 25% EPDM content in the blend. The Avrami model has been successfully applied to describe the crystallization kinetics of the blend. The kinetic curves obtained under non-isothermal conditions confirm the results obtained under isothermal conditions and demonstrate the nucleant action of the EPDM phase on the PP crystallization.
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  • 99
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    Journal of thermal analysis and calorimetry 62 (2000), S. 721-727 
    ISSN: 1572-8943
    Keywords: kinetics ; metal exchange ; thermaldehydration ; zeolite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Zeolite-4A is a hydrated aluminosilicate which becomes more hydrated when exchanged with transition metals. In this work, the dehydration kinetics of cobalt, nickel and copper(II)-exchanged zeolite-4A were studied by means of TG and DTA over the temperature range from 20 to 500°C, and the numbers of water molecules in the metal-exchanged zeolite samples were calculated. It was observed that, as the ionic radius of the hydrated metal increased, the number of water molecules also increased. The loss of water from the zeolite samples generally occurred in the temperature range 100–300°C and was manifested in the DTA graphs by an extended endothermic effect. The DTA curves demonstrated that the peak position shifted towards lower temperatures as the metal concentration increased or, in other words, the water of hydration increased. The kinetic parameters (order of reaction and activation energy) were calculated via the Coats and Redfern method. The process of dehydration was found to follow first-order kinetics.
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  • 100
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    Journal of thermal analysis and calorimetry 63 (2000), S. 359-374 
    ISSN: 1572-8943
    Keywords: KEKAM equation ; kinetics ; thermal dissociation of solids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Relationships have been established between the average conversion degree and the dissociation time for polydisperse granular material, taking its grain size distribution into account. It has been checked in which cases the kinetic curves obtained by a numerical solution can be described in terms of KEKAM equation.
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