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  • 1
    Electronic Resource
    Electronic Resource
    The influence of ion energy, ion flux, and etch temperature on the electrical and material quality of GaAs etched with an electron cyclotron resonance source (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 2712-2715 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The residual damage incurred to GaAs via etching with a Cl2/Ar plasma generated by an electron cyclotron resonance (ECR) source was investigated as a function of variations in ion energy, ion flux, and etching temperature. The residual damage and electrical properties of GaAs were strongly influenced by changes in these etching parameters. Lattice damage was incurred in all processing situations in the form of small dislocation loops. GaAs etched at high ion energies with 200 W rf power, exhibited a defect density five times higher than GaAs etched at lower ion energies with 20 W rf power. This enhanced residual damage at the higher rf powers was paralleled by a degradation in the unannealed contact resistance. Higher etch rates, which accompany the higher rf power levels, caused the width of the disordered region to contract as the rf power was elevated. Therefore, the residual etch damage is influenced by both the generation and removal of defects. Increasing the microwave power or ion flux resulted in elevating the residual defect density, surface roughness, and unannealed contact resistance. GaAs etched at high temperatures, ∼350 °C, resulted in a lower contact resistance than GaAs etched at 25 °C. The high temperature etching augmented the defect diffusion which in turn lowered the near surface defect density. This decrease in residual damage was deemed responsible for improving the electrical performance at 350 °C. The electrical measurements were found to be more sensitive to the density of defects than the vertical extent of disorder beneath the etched surface. Results of this investigation demonstrate that in order to minimize material damage and improve electrical performance, etching with an ECR source should be performed at low rf and microwave powers with a high substrate temperature. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360067
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  • 2
    Electronic Resource
    Electronic Resource
    Magnetic phase transitions in (Fe1−xTx)3Ga4 alloys (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 4879-4881 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The magnetic ordering in the series of transition metal alloys (Fe1−xTx)3Ga4 with T=Ni and Ti having values of x in the range 0.05≤x≤0.20 has been investigated at high fields and low temperatures. Magnetization measurements revealed that in contrast to other T substitutions, Ni and Ti induce completely different types of effects on the magnetic properties. In the case of Ni substitution a ferrimagnetic-like type of magnetic order is induced at low compositions and low temperatures and Ti produces a ferromagnetic ground state. For Ti alloys with low composition as the temperature is increased a field induced transition starts to appear at about 50 K which persists up to room temperature suggesting a phase transition from a ferromagnetic to an antiferromagnetic state. The phase diagrams of the Ni and Ti system are explainable in terms of the Moriya-Usami and Isoda theories. Preliminary neutron diffraction measurements on the Ni alloys carried out at ILL suggest the existence of short-range order over a certain temperature range. The behavior observed so far on the various substituted systems leads us to believe that there is a clear relation between the magnetic properties and the relative position of the substitution element with respect to Fe in the Periodic Table. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.373189
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of electron cyclotron resonance etching on the ambient (100) GaAs surface (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 3054-3055 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Photoreflectance has been used to study the electronic behavior of the ambient (100) GaAs surface and its modification by etching in a Cl2/Ar plasma generated by an electron-cyclotron resonance (ECR) source. We observed two pinning positions for ambient (100) GaAs, with n-GaAs pinning near midgap and p-GaAs pinning near the valance band. ECR etching shifts the Fermi level of p-GaAs toward midgap, but has little effect on n-GaAs. The surface modification is most influenced by the rf power. Auger electron spectroscopy indicates that the etching increases As at the GaAs/oxide interface. We suggest that the Ga/As ratio controls the position of the Fermi level. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.114275
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  • 4
    Electronic Resource
    Electronic Resource
    Pump-energy-dependent photo-ionization and collisional ionization in two-photon-resonant- and three-photon-ionization processes (1998)
    Springer
    Applied physics 66 (1998), S. 617-620 
    Details
    ISSN: 1432-0649
    Keywords: PACS: 32.80.Rm; 34.50.Fa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003400050446
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  • 5
    Electronic Resource
    Electronic Resource
    The epidemiology and surveillance of blood lead in Taiwan (R.O.C.): A report on the PRESS-BLL project (1997)
    Springer
    International archives of occupational and environmental health 69 (1997), S. 386-391 
    Details
    ISSN: 1432-1246
    Keywords: Key words Blood lead level (BLL) ; Surveillance ; Occupational health ; Field survey ; PRESS-BLLs project
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  To monitor the lead hazards in industries and to investigate the prevalence of elevated blood lead levels (BLLs) in lead-exposed workers, a lead surveillance system (PRESS-BLLs) has been established and operated in Taiwan, Republic of China, since July 1993. A cohort of lead-exposed workers who received a periodic annual health examination at 55 accredited hospital laboratories was constructed. A total of 9807 separate BLL measurements were reported to the system in 1994. The mean BLL was 15.8 μg/dl in male workers and 11.6 μg/dl in female workers. The mean BLL of lead-exposed workers was significantly (P〈0.05, z-test) higher than that of the general Taiwanese population (8.6 μg/dl for males and 6.7 μg/dl for females). In addition, the BLLs of 983 (10.0%) workers exceeded the regulatory action level (40 μg/dl for males; 30 μg/dl for females). The workplaces and homes of 57% of the workers with elevated BLLs were thoroughly investigated to determine the sources of lead contamination. These actions identified the causes of elevated BLLs and set up strategies to reduce workers’ lead exposure. The establishment of this occupational lead surveillance system represents a method for monitoring of lead hazards from occupational and environmental settings to prevent lead poisoning. The information acquired from the system can help in the setting up of a priority of prevention and the development of control measures. It is also useful for further monitoring of changes in the BLLs of the lead-exposed-worker cohort. The Health Department of Taiwan can use this information to evaluate the effectiveness of current industrial hygiene practice. Subjects with elevated BLLs have been medically treated and placed on long-term follow-up for sequelae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004200050165
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  • 6
    Electronic Resource
    Electronic Resource
    Risk factors for high blood lead levels among the general populationin Taiwan (1998)
    Springer
    European journal of epidemiology 14 (1998), S. 775-781 
    Details
    ISSN: 1573-7284
    Keywords: High blood lead ; Risk factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Purpose: Environmental and occupational lead pollution is a common problem in both developing and industrialized countries. The purpose of this study is to evaluate the risk factors for high blood lead levels among the general population in Taiwan. Methods: After multi-stage sampling, we randomly selected 2803 subjects (1471 males and 1332 females) for this study. Univariate and multivariate logistic regression analyses were conducted to evaluate the risk of high blood lead. To control for differences in age and gender, all analyses were with age-adjusted and gender-stratified. Results: Among males, the mean age is 46 years (15 to 85 years), mean and median blood lead levels is 7.3 and 6.3μg/dl, respectively. Among females, the mean age is 43 years (15 to 84 years), mean and median blood lead level is 5.7 and 4.8μg/dl, respectively. Among males, the history of herbal drug use, drinking water from well or spring sources, and occupational lead exposure are significantly different between relatively high and normal blood lead level subjects. The history of occupational lead exposure, history of herbal drug use, and well or spring sources of drinking water are the major risk factors for high blood lead with odds ratio of 4.62 (95% CI: 2.82–7.55), 3.09 (95% CI: 1.60–5.97), 2.06 (95% CI: 1.13–3.76), and 2.37 (95% CI: 1.39–4.04), respectively. Among females, these characteristics remain important except the sources of drinking water. The history of herbal drug use and occupational lead exposure become the major risk factors for high blood lead with odds ratio of 2.94 (95% CI: 1.26–6.88) and 7.72 (95% CI: 3.51–16.99), respectively. In multivariate logistic regression analyses, we find that the risk factors for high blood lead in both genders include a history of herbal drug use and occupational lead exposure. Among males, the drinking water sources and factories in the neighboring areas are also significant factors for high blood lead. Conclusions: For the goal of reducing prevalence of high blood lead by the year 2000, the improvement and monitoring of the working environment, the careful attention to herbal drug use and the lead-free drinking water sources should be executed as thoroughly as possible to reduce the probability of lead pollution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007544205378
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  • 7
    Electronic Resource
    Electronic Resource
    Bicarbonate permeability and immunological evidence for an anion exchanger-like protein in the red blood cells of the sea lamprey, Petromyzon marinus (1996)
    Springer
    Journal of comparative physiology 166 (1996), S. 197-204 
    Details
    ISSN: 1432-136X
    Keywords: Anion movements ; Chloride/bicarbonate exchange ; Red cell proteins ; AE1 or band 3 ; Petromyzon marinus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Physiological and immuno-blotting experiments were used to determine whether the red blood cell membrane of a primitive vertebrate, the sea lamprey Petromyzon marinus, contained a counterpart similar to the vertebrate anion exchange protein known as AE1 or band 3. Results of the physiological experiments which measured CO2 production after adding H14CO 3 - to the extracellular saline, indicated significant transmembrane bicarbonate movement in lamprey blood which unlike that in most vertebrates, was insensitive to inhibition by 4,4′ diisothiocyanatostilbene-2,2′ disulfonic acid. The present study also showed that lamprey red blood cells possess acetazolamide-sensitive carbonic anhydrase which is an important component of CO2 production by vertebrate red blood cells. Polyclonal immunoglobulins against a 12 amino acid domain in the C-terminus of the mouse AE1 recognized a trout red blood cell membrane protein with a relative molecular mass of 97 kDa, but failed to immunoreact with any membrane proteins from the red blood cells of lamprey. Antibodies against trout AE1 immunoreacted with trout red blood cell membrane proteins of approximately 97 kDa, 200 kDa and 〉200 kDa. Interestingly, only a 200-kDa membrane protein from the red blood cells of the primitive lamprey immunoreacted with the trout anti-AE1 immunoglobulin proteins. Therefore, lamprey red blood cells appear to possess an AE1-like protein that may be physiologically different than that in most other vertebrates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00263983
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  • 8
    Electronic Resource
    Electronic Resource
    Unique distribution of the anion exchange protein in the sea lamprey, Petromyzon marinus (2000)
    Springer
    Journal of comparative physiology 170 (2000), S. 497-504 
    Details
    ISSN: 1432-136X
    Keywords: Key words Anion exchange ; AE1 ; Red blood cells ; Lamprey ; Respiration ; AbbreviationsA carbonic anhydrase activity ; CA carbonic anhydrase ; DIDS 4,4′ diisothiocyanatostilbene-2,2′ disulphonic acid ; GTC-AP guanidium isothiocyanate-acid phenol ; IgGs type G immunoglobins ; P red blood cell HCO−3 permeability ; PCR polymerase chain reaction ; rbc(s) red blood cell(s)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The purpose of the present study was to examine the distribution of the anion exchange protein in the sea lamprey. Southern blots showed that genomic DNA of juvenile lampreys possesses several regions that are similar to segments of the AE gene from other vertebrates. However, physiological experiments examining rapid anion fluxes across the red blood cell (rbc) membrane and molecular experiments examining mRNA transcript levels both indicated that the anion exchange protein is absent in sea lamprey rbcs. In contrast, lamprey kidney, skeletal muscle, liver and heart tissue all appeared to possess mRNA transcripts for an AE protein. Further evidence for the presence of an AE protein in kidney tissue was obtained from Western blots. In order to evaluate the impact of the apparent rbc anion exchange limitations, the bicarbonate permeability of lamprey rbcs was also evaluated using mass spectrometry. The bicarbonate permeability of the lamprey rbc membrane was an order of magnitude lower than that of trout rbcs. Taken together, these results indicate that the gene for the AE protein is indeed present in lampreys, but it is not expressed in the rbc. Moreover, the process of CO2 transport in lamprey probably does not involve bicarbonate transport across the rbc membrane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003600000127
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  • 9
    Electronic Resource
    Electronic Resource
    The Genetically Epilepsy-Prone Rat (GEPR) (1995)
    Springer
    Neurological sciences 16 (1995), S. 91-99 
    Details
    ISSN: 1590-3478
    Keywords: GEPR ; Genetically Epilepsy-Prone Rats ; seizures ; epilepsy ; forebrain seizure ; brainstem seizure ; electroencephalography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Sommario Due ceppi indipendenti di ratti geneticamente suscettibili ad epilessia (GEPRs) sono stati ottenuti mediante reincroci. GEPR-3s e GEPR-9s differiscono per il grado di predisposizione alle crisi della loro espressione rispettivamente moderato e importante. La predisposizione alle crisi stabilisce una distinzione fondamentale tra cervello normale ed epilettico. Sia nei GEPRs che nell'uomo la predisposizione alle crisi riguarda sia le crisi spontanee sia il grado di responsività o la soglia di risposta a stimoli che possono causare crisi anche in soggetti non epilettici. L'attivazione di circuiti epilettogeni del tronco da parte dell'input uditivo, attraverso il collicolo inferiore, provoca nei GEPR-9s risposte elettrografiche e comportamentali che riproducono le crisi generalizzate tonico-cloniche dell'uomo. L'attivazione dei circuiti epilettogeni del tronco da parte di circuiti epilettogeni proencefalici nei GEPRs rappresenta un modello recentemente individuato di crisi parziali complesse con generalizzazione secondaria a crisi tonico-cloniche. Per questi motivi la predisposizione epilettica nei GEPRs rappresenta una opportunità privilegiata per lo studio delle epilessie umane non riscontrabile in studi sul cervello normale esposto a stimoli epilettogeni.
    Notes: Abstract Two independently inbred strains of genetically epilepsy-prone rats (GEPRs) have been developed. GEPR-3s and GEPR-9s have moderate and severe degrees of seizure predisposition as well as expression, respectively. Seizure predisposition is a fundamental distinction between the normal and epileptic brain. Seizure predisposition in GEPRs and in humans with epilepsy includes spontaneous seizures and exaggerated seizure responsiveness and/or abnormally low thresholds to stimuli which also cause seizures in non-epileptic subjects. Activation of brainstem seizure circuitry by auditory input via the inferior colliculus causes electrographic and behavioral responses in GEPR-9s which replicates human generalized tonic/clonic seizures. Activation of brainstem seizure circuitry by input from forebrain seizure circuitry in GEPRs provides a newly discovered model of complex partial seizures with secondary generalization to tonic/clonic seizures. Thus, seizure predisposition in GEPRs offers a unique opportunity to study the human epilepsies that is not offered in studies of normal brain exposed to convulsant stimuli.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02229080
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