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  • 1
    Electronic Resource
    Electronic Resource
    Characteristic modifications of the breathing pattern of mice to evaluate the effects of airborne chemicals on the respiratory tract (1993)
    Springer
    Archives of toxicology 67 (1993), S. 478-490 
    Details
    ISSN: 1432-0738
    Keywords: Breathing pattern ; Mice ; Airborne chemicals ; Respiratory tract
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A system was developed for exposure of unanesthetized mice to airborne chemicals and for continuous measurement of their breathing pattern prior to, during and following exposure. By measuring inspiratory and expiratory airflows (VI and VE), and integration with time to yield tidal volume (VT), we obtained characteristic modifications to the normal breathing pattern. These permitted recognition that a specific portion of the respiratory tract was affected by the selected airborne chemicals. Following recognition, we also quantitated the degree of effect using one specific measurement in each case. An effect on the upper respiratory tract, induced by the sensory irritant, 2-chlorobenzylchloride, was quantitated by measuring a decrease in respiratory frequency. An effect on the conducting airways, induced by the airway constrictor, carbamylcholine, was quantitated by a decrease in VE at the mid-point of VT. An effect at the alveolar level, induced either by the vagal nerve ending stimulant, propranolol, or by the pulmonary irritant, machining fluid G, was quantitated by an increase in the length of a pause induced at the end of expiration. The system is easy to construct and operate and can be used to rapidly evaluate the effects of airborne chemicals on the respiratory tract.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01969919
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  • 2
    Electronic Resource
    Electronic Resource
    An approach for evaluating the respiratory irritation of mixtures: application to metalworking fluids (1995)
    Springer
    Archives of toxicology 69 (1995), S. 671-676 
    Details
    ISSN: 1432-0738
    Keywords: Key words Metalworking fluids ; Pulmonary irritation ; Mice ; Mixtures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Recently, the sensory and pulmonary irritating properties of ten metalworking fluids (MWF) were assessed using a mouse bioassay. Relative potency of the MWFs was estimated, but it was not possible to identify the component(s) responsible for the the respiratory irritation induced by each MWF. One of the ten fluids, MWF “E”, produced sensory and pulmonary irritation in mice, and it was of moderate potency in comparison to the other nine MWFs. MWF “E” had three major components: tall oil fatty acids (TOFA), sodium sulfonate (SA), and paraffinic oil (PO). In the present study, the sensory and pulmonary irritating properties of these individual components of MWF “E” were evaluated. Mixtures of the three components were also prepared and similarly evaluated. This analysis revealed that the sensory irritation from MWF “E” was largely due to TOFA, whereas SA produced the pulmonary irritation observed with MWF “E”. Both TOFA and SA were more potent irritants than was MWF “E”, and the potency of TOFA and/or SA was diminished through combination with PO. There was no evidence of synergism of the components when combined to form MWF “E”. This approach for identifying the biologically “active” component(s) in a mixture should be useful for other MWFs. Furthermore, the approach should be easily adapted for other applications involving concerns with mixtures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050230
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  • 3
    Electronic Resource
    Electronic Resource
    Structure-activity relationships of volatile organic chemicals as sensory irritants (1998)
    Springer
    Archives of toxicology 72 (1998), S. 125-140 
    Details
    ISSN: 1432-0738
    Keywords: Key words Sensory irritation ; Structure activity relationship ; Quantitative structure-activity relationships ; QSAR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We used a database of 145 volatile organic chemicals for which the sensory irritation potency (RD50) has been reported in mice. Chemicals were first separated into two groups: nonreactive and reactive, using Ferguson's rule. This rule suggests that nonreactive chemicals induce their effect via a physical ( p) mechanism (i.e., weak forces or interactions between a chemical and a biological receptor). Therefore, appropriate physicochemical descriptors can be used to estimate their potency. For reactives, a chemical (c) mechanism (i.e., covalent bonding with the receptor) would explain their potency. All chemicals were also separated on the basis of functional groups and subgroups into 24 classifications. Our results indicated that the potency of nonreactive chemicals, regardless of their chemical structure, can be estimated using a variety of physicochemical descriptors. For reactive chemicals, we identified five basic reactivity mechanisms which explained why their potency was higher than that estimated from physicochemical descriptors. We concluded that Ferguson's proposed rule is adequate initially to classify two separate mechanisms of receptor interactions, p vs c. Several physicochemical descriptors can be used to estimate the potency of p chemicals, but chemical reactivity descriptors are needed to estimate the potency for c chemicals. At present, this is the largest database for nonreactive-reactive chemicals in toxicology. Because of the wide variety of c chemicals presented, a semi-quantitative estimate of the potency of new, or not previously evaluated, c chemicals can be arrived at via comparison with those presented and the basic chemical reactivity mechanisms presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050479
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  • 4
    Electronic Resource
    Electronic Resource
    Changes in different regions of hepatitis B virus gene in hepatitis B ‘e’ antigen-negative patients with chronic hepatitis B: the effect of long-term lamivudine therapy (2005)
    Oxford, UK : Blackwell Science Ltd
    Alimentary pharmacology & therapeutics 21 (2005), S. 0 
    Details
    ISSN: 1365-2036
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background : Lamivudine therapy for chronic hepatitis B has been associated with changes in different regions of the hepatitis B virus nucleotide sequence.Aim : To study changes in the sequences of polymerase and precore/core promoter regions of hepatitis B virus, before and during 5 years of therapy with lamivudine.Methods : Eighty consecutive samples were taken from 10 chronic hepatitis B ‘e’ antigen-negative patients.Results : Nine patients carried hepatitis B virus precore mutations during the study. Before therapy, wild type was replaced by A1896 in two (20%) cases. During treatment, A1896 reverted transitory to wild type in five cases (50%) and in one case wild type was replaced by A1896. The continuous detection of precore mutations during therapy was associated with a lower response rate.YMDD mutations were observed in nine cases and both, L180M and M204V/I mutations were simultaneously detected in six cases. About 75% of the patients with M204V mutations were responders and none with M204I or mixed pattern sustained response.Conclusion : Hepatitis B ‘e’ antigen-negative patients exhibit changes in the precore regions both spontaneously and under lamivudine therapy, the transitory reversion to wild type being most frequently witnessed. Patients carrying M204V mutations are more likely to respond to therapy. If, in further studies, these results are confirmed some patients with YMDD mutations could benefit from prolonging the duration of lamivudine therapy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2036.2005.02503.x
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  • 5
    Electronic Resource
    Electronic Resource
    THE CONSECUTIVE WÖHLER CURVE APPROACH TO DAMAGE ACCUMULATION (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Fatigue & fracture of engineering materials & structures 19 (1996), S. 0 
    Details
    ISSN: 1460-2695
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract— From the engineering point of view no reliable lifetime prediction method exists, which would enable the life expectancy of structures to be calculated with sufficient accuracy. One of the primary drawbacks of current approaches is their obvious inability to adequately include into an engineering calculation scheme basic knowledge of the microstructural response to cyclic loads during each of the stages of the fatigue process. This article gives a brief introduction into the Consecutive Wöhler Curve Approach which, it is suggested, is capable of predicting with enhanced accuracy fatigue life under varying amplitude conditions. The load interaction behaviour, which is intimately connected with the material's microstructure, is included through “fatigue functions” which are derived from two-step Wöhler tests.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-2695.1996.tb00974.x
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  • 6
    Electronic Resource
    Electronic Resource
    Respiratory effects of a synthetic metalworking fluid and its components (1996)
    Springer
    Archives of toxicology 70 (1996), S. 195-201 
    Details
    ISSN: 1432-0738
    Keywords: Key words Respiratory effects ; Metalworking fluid ; Mouse bioassay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  A synthetic metalworking fluid, MWF “A”, and its major components were evaluated using a previously developed mouse bioassay. This fluid and its components evoked sensory (S) and pulmonary (P) irritation in mice. For MWF “A” and each of its components, a concentration-response relationship was developed on the basis of respiratory frequency (fR) responses. From such relationships, the concentration capable of evoking a 50% decrease in mean fR was determined for MWF “A” and each component (RD50). RD50S or RD50P was used to distinguish decreases in fR that were due to sensory irritation (S) from those due to pulmonary irritation (P). From RD50P values, it was concluded that the fatty acid alkanolamide condensates, tolutriazole, and triazine-type biocide components were similar in potency to one another and similar in potency to MWF “A”. By examining potency and fractional composition, it was concluded that the fatty acid alkanolamide condensates and the triazine-type biocide largely contributed to the irritancy of MWF “A”. From RD50P values, occupational exposure limits were proposed for MWF “A” and each of its components. The current Threshold Limit Value of 10 mg/m3 established by the American Conference of Governmental Industrial Hygienists for “particulates not otherwise classified” (PNOC) would be inadequate to protect workers from the irritating properties of MWF “A” and most of its components.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050260
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  • 7
    Electronic Resource
    Electronic Resource
    Computer assisted recognition and quantitation of the effects of airborne chemicals acting at different areas of the respiratory tract in mice (1994)
    Springer
    Archives of toxicology 68 (1994), S. 490-499 
    Details
    ISSN: 1432-0738
    Keywords: Key words: Sensory irritation – Pulmonary irritation – Airflow limitation – Mice – Airborne chemicals – Propranolol – Carbamylcholine – 2-Chlorobenzylchloride – Trigeminal nerve endings – Vagal nerve endings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The pattern and timing of a normal breath in unanesthetized mice was analyzed from measurement of inspiratory and expiratory airflows (V.I and V.E). Airflow was measured via a differential pressure transducer, attached to a pneumotachograph, which itself was attached to a body plethysmograph into which a mouse was placed. The analog voltage from the differential pressure transducer was digitized and stored for analysis on a microcomputer. Criteria were developed to classify each breath as normal (N) or belonging into one of seven abnormal categories. The abnormal categories were arrived at by computer analysis, recognizing specific modifications of the normal pattern into patterns of: sensory irritation of the upper respiratory tract (S), airflow limitation within the conducting airways of the lungs (A) or pulmonary irritation at the alveolar level (P). Combinations of these effects, i.e., S+A, P+A, P+S and P+S+A were also recognized. Computer analysis of each breath also permitted quantitative evaluation of the degree of S, A or P abnormalities. To induce each type of effect we used inhalation exposures to 2-chlorobenzylchloride, carbamylcholine or propranolol. We propose that this approach will permit rapid evaluation of the possible effects of airborne chemicals at three levels of the respiratory tract, with the classification of the type of effect easily obtained in an objective way using well defined criteria, followed by quantitation of the degree of each effect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050101
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  • 8
    Electronic Resource
    Electronic Resource
    Influence of hydrogen on deformation and torsional fracture of high-strength steel (1994)
    Springer
    Materials science 29 (1994), S. 413-419 
    Details
    ISSN: 1573-885X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566452
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  • 9
    Electronic Resource
    Electronic Resource
    Description of behavior of short fatigue cracks (1990)
    Springer
    Materials science 25 (1990), S. 456-459 
    Details
    ISSN: 1573-885X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00731934
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  • 10
    Electronic Resource
    Electronic Resource
    Eine neue Methode zur Festigkeits- und Zähigkeitsbestimmung von dünnen Schichten (1997)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 28 (1997), S. 124-130 
    Details
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: A New Method of Determining Strength and Fracture Toughness of Thin FilmsA method is presented for measuring strength and fracture toughness of thin films. The basic idea of this method is to use a compact steel specimen as a substrate, which is deeply precracked by means of fatigue loading prior to the coating process. Under bend loading of this composite crack opening occurs accompanied by straining the free-standing thin film which bridges the crack. Film rupture firstly occurs at the front face of the specimen followed by crack growth on both sides. The film properties can be derived by eliminating the substrate effect through determining the difference between the two load-displacement curves corresponding to the intact and the damaged film, respectively. The strength of the film can be calculated from the load difference at film rupture at the front face of the composite. The fracture toughness is evaluated from load and compliance change during successive crack growth on both sides of the specimen. First results on PACVD TiN-films are presented and compared with available bulk data, thus demonstrating the applicability of the proposed method.
    Notes: Es wird eine Methode vorgestellt, mit der es möglich ist, Festigkeits- und Zähigkeitsparameter von dünnen Schichten auf relativ einfache Weise zu bestimmen. Dazu werden Stahlsubstratproben vor den Beschichtung mit einem langen Ermüdungsanriß versehen. Bei einer Biegebelastung derart präparierter Proben wird die Schicht im Bereich des sich öffnenden Anrisses gedehnt und schließlich zerrissen. In diesem sehr schmalen Bereich kann die Schicht als freistehend betrachtet werden. Die Schicht reißt zuerst an der Probenstirnseite, danach an den beiden Probenseiten. Aus der Differenz zweier Kraft-Weg-Messungen während und nach dem Schichtriß läßt sich der Schichteinfluß vom Substrateinfluß separieren. Aus der auf die Schicht wirkenden Kraft beim Schichtriß an der Stirnseite kann die Festigkeit der Schicht (Streckgrenze und Zugfestigkeit) bestimmt werden. Aus der kritischen Schichtkraft und der zugehörigen Nachgiebigkeitsänderung infolge Schichtriß an beiden Probenseiten ergibt sich die Bruchzähigkeit der Schicht. Erste Messungen und Ergebnisse an einer PACVD-TiN-Hartstoffschicht, die die prinzipielle Anwendbarkeit der Methode demonstrieren, werden vorgestellt.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mawe.19970280311
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