bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of rapid thermal annealing on the electrical properties of ion‐beam‐synthesized oxide layers using 12 keV O2+ bombardment of Si
Authors: Deenapanray Prakash N. K. 
Published: September 2002

AbstractSurface layers of SiO2 were synthesized by bombarding n‐type Si samples with 12 keV O2+ ions at 10° incidence in a SIMS instrument. The oxide layers were annealed at 950 °C for 3, 6 or 8.5 min under Ar flow in a rapid thermal annealer. Temperature‐dependent current–voltage (I–V–T) measurements were used in order to establish both the dielectric quality and the current transport mechanisms across the dielectric layers. Annealing for 8.5 min doubled the breakdown voltage while decreasing the leakage current by a factor of ∼18. The ohmic quality of the layers for the low field strengths decreased with the increasing annealing time, which is related to the removal of implantation damage as observed by high‐resolution RBS measurements. For the high field strengths, the tunnelling effect was most dominant for the oxide annealed for 8.5 min. The breakdown voltage of oxide layers exhibited an Arrhenius‐like dependence on the sample temperature, with the activation energy for breakdown decreasing with the increasing annealing time. Deep‐level transient spectroscopy (DLTS) and capacitance–voltage (C–V) measurements also were used to characterize the samples. Copyright © 2001 John Wiley & Sons, Ltd.
AES quantification of intergranular film thickness in the Ni–Bi system with respect to the liquid metal embrittlement phenomenon
Authors: Wolski K. , Marié N. , Biscondi M. 
Published: September 2002

AbstractIntergranular penetration of liquid bismuth‐rich alloy in solid polycrystalline nickel is investigated at 700° C. Short intergranular films of micrometric thickness with a very acute tip are observed by SEM. Intergranular penetration of Bi–Ni alloy induces strong intergranular brittleness that extends far ahead of the micrometric film tip. Very long intergranular films of nanometric thickness are identified by AES after in situ intergranular fracture. A quantitative model aimed at the determination of the actual thickness of these films is developed and described in detail. The measured bismuth/nickel intensity ratios (IBi/INi) are correlated to the thickness of the intergranular film. Detailed procedures related to the determination of the experimental IBi/INi ratio as well as all assumptions related to the quantification model are clearly stated. Atomic densities, attenuation lengths and retrodiffusion factors are calculated whereas effective cross‐sections, probabilities of de‐excitation by the Auger process and the transmission efficiency of the analyser are suppressed from the final formulae due to reference measurements on the bulk Bi–Ni embrittling alloy, which is used as a bicomponent standard of known composition. Numerical application gives a value of 2–4 nm for the thickness of the film formed during 8 h at 700° C. The uncertainty mainly comes from the difficulty in determination of the Auger electron collection angle, due to the use of polycrystals. Interest for the use of bicrystals is underlined. It is postulated that the mechanisms of liquid metal embrittlement (LME) should be analysed with respect to the tip of this nanometric film. Copyright © 2001 John Wiley & Sons, Ltd.
Auger electron appearance potential spectroscopy study of CrNx films
Authors: Chourasia A. R. , Hood S. J. 
Published: September 2002

AbstractThin films of chromium nitride deposited with varying concentrations of nitrogen on stainless steel substrates have been studied using Auger electron appearance potential spectroscopy (AEAPS). This technique provides information on the density of states in the conduction band. The chromium L2,3 levels have been investigated. The normalized AEAPS chromium spectra in the films have been compared with the elemental chromium spectrum. The signal strength at the Fermi level (EF) is observed to be larger in the films. This represents an increase in the density of states at EF for the films as compared with that of elemental chromium. However, in the films, the density of states is found to decrease with increasing nitrogen concentration. The binding energy of the chromium L3 level for the films exhibits a positive chemical shift with respect to elemental chromium. These spectral data indicate a direction of charge transfer from chromium to nitrogen. In the films, the charge transfer is observed to decrease with increasing nitrogen content. We also present a scheme to estimate the Coulomb correlation energy using the chromium L3 core‐level binding energy data obtained from AEAPS and x‐ray photoelectron spectroscopy (XPS). A decrease in the correlation energy with increasing nitrogen content is observed for the films. We also have estimated the total density of unoccupied states above EF from the experimental data. This total density is observed to be more in the films than in elemental chromium. In the films, the total density of states decreases with nitrogen concentration. The AEAPS spectral results have been correlated with our earlier XPS results on these films. Copyright © 2001 John Wiley & Sons, Ltd.
Diabetes teratogenicity in mice is accompanied with distorted expression of TGF‐β2 in the uterus
Authors: Fein A. , Magid N. , Savion S. , Orenstein H. , Shepshelovich J. , Ornoy A. , Torchinsky A. , Toder V. 
Published: September 2002

AbstractEarly embryonic deaths as well as malformed newborns are among complications of the diabetic pregnancy. Cytokines and growth factors operating in the embryonic vicinity are found to be among factors that determine the sensitivity of embryos to external and internal detrimental stimuli, including diabetes. Transforming Growth Factor‐β2 (TGF‐β2) has been shown to be essential for embryonic development and survival. In the present work, we evaluated the pattern of TGF‐β2 expression in the uterus of streptozotocin‐induced diabetic mice, demonstrating a decreased reproductive performance and elevated percentage of litters with severely malformed fetuses. Since stimulation of the maternal immune system was found to increase the resistance of mouse embryos to the teratogenic effect of diabetes, the effect of immunopotentiation on the expression of the cytokine was also investigated. TGF‐β2 expression was studied at the mRNA level by using the in situ hybridization technique and at the protein level by using the immunohistochemical analysis. A clear decrease in TGF‐β2 mRNA expression in the uterus of diabetic mice was observed at examined time points: days 1, 5, and 9 of pregnancy. Also, an evident reduction in TGF‐β2, the protein expression in the uterus of diabetic mice, was demonstrated at these time points. Maternal immunopotentiation that improved the reproductive performance of diabetic mice and reduced the number of the litters with malformed fetuses was also accompanied by a clear increase in the level of TGF‐β2 mRNA expression in the pregnant uteri. The above results clearly demonstrate that the embryotoxic effect of diabetes is accompanied by an alteration of TGF‐β2 expression. Immunopotentiation that was shown to improve the reproductive performance of the diabetic mice was accompanied by a partial normalization of TGF‐β2 expression in embryonic vicinity. Teratogenesis Carcinog. Mutagen. 22:59–71, 2002. © 2002 Wiley‐Liss, Inc.
The role of radicals in enzymatic processes
Authors: Frey Perry A. 
Published: September 2002

AbstractResearch on the mechanism of action of coenzyme B12, adenosylcobalamin, as a graduate student introduced the author to the field of organic free radicals in enzymology. Twenty years later, related work on S‐adenosylmethionine (SAM) as a “poor man’s coenzyme B12” was initiated in a detailed analysis of the mechanism of action of lysine 2,3‐aminomutase (LAM). The interconversion of l‐lysine and l‐β‐lysine is catalyzed by LAM, which requires SAM, pyridoxal‐5′‐phosphate (PLP), and a [4Fe–4S] cluster as coenzymes. The mechanism of this reaction has been delineated as a radical isomerization, in which radical formation is initiated by the [4Fe–4S]‐dependent cleavage of the SAM into methionine and the 5′‐deoxyadenosyl radical. The mechanism of this process is discussed, together with the role of this radical in hydrogen abstraction from lysine to initiate the substrate radical isomerization. The chemistry underlying the functions of SAM, PLP, and [4Fe–4S] in the action of LAM is novel in all respects, except for the formation of a lysine‐PLP aldimine at the active site. Of the four free radicals in the mechanism, three have been characterized by EPR spectroscopy. In the suicide inactivation of adenosylcobalamin‐dependent dioldehydrase (DDH) by glycolaldehyde, the formation of cob(II)alamin and 5′‐deoxyadenosine is accompanied by the conversion of glycolaldehyde to cis‐ethanesemidione radical at the active site. The cis‐ethanesemidione radical has been characterized by EPR spectroscopy. Its exceptional stability at the active site is the basis for the inactivation of DDH by glycolaldehyde. © 2001 John Wiley & Sons, Inc. and The Japan Chemical Journal Forum Chem Rec 1:277–289, 2001
Selection bias in Teratology Information Service pregnancy outcome studies
Authors: Johnson K. A. , Weber P. A. , Jones K. L. , Chambers C. D. 
Published: September 2002

AbstractBackgroundPregnancy outcome studies conducted through Teratology Information Services (TIS) rely on volunteer subjects. If these subjects tend to have different risk profiles than the population from which they are drawn, the results of TIS studies may have limited generalizability.MethodsWe selected all subjects who enrolled in the California Teratogen Information Service (CTIS) pregnancy outcome study for prenatal exposure to carbamazepine or valproic acid between 1990 and 1997 and who received prenatal care through Kaiser Permanente of Southern California (n = 13). We compared these subjects to Kaiser patients identified through the Maternal Serum Alpha Fetoprotein Program with exposure to carbamazepine or valproic acid but who had not enrolled in the CTIS project. The controls were matched by Kaiser location and pregnancy year using a 2:1 ratio (n = 26). Medical records were reviewed and the prevalence of 14 pregnancy risk factors was compared between the two groups.ResultsThere were no significant differences between the groups on any one risk factor; however, a notably higher proportion of women who did not enroll in the CTIS study used tobacco or had a positive family history of congenital anomalies.ConclusionsAlthough the sample was small, and results may not apply to other exposures in different health care environments, these data provide some evidence that women who enroll in TIS pregnancy outcome studies do not have a substantially different pregnancy risk profile than women who do not. Efforts to address possible selection bias should be incorporated in future TIS study design. Teratology 64:79–82, 2001. © 2001 Wiley‐Liss, Inc.
Predatory behavior of the snake Bothrops jararaca and its adaptation to captivity
Authors: Troncone Lanfranco R.P. , Silveira Paulo F. 
Published: September 2002

AbstractHabituation to captivity is difficult for some species. Understanding the motivational elements involved in predation may ease this habituation. Seventy‐one Brazilian jararaca snakes (Bothrops jararaca [Wied, 1824], Viperidae, Crotalinae) recently captured and never fed in captivity were tested for predatory behavior on rodents. Lighting was adapted to allow predatory sessions to occur during the first hours of the night when these animals are more active. Up to three prey subjects were presented in a session. In the first experiment, the preference for prey size and color was assessed using albino and dark‐colored rodents. In a second experiment, a group of snakes was submitted to 12 sessions during a period of almost 2 years. The strike strategy was classified in one of two categories: envenomation (E) or seizing (S). Envenomation involved a bite delivered by the snake with prompt retrieval of the head; holding the rodent in the snake’s jaws since the first strike, without retrieving the fangs and holding the prey during venom action, characterized S strike. Trailing and swallowing the dead prey always followed E strike. Results suggest that snakes fed more often on larger subjects. The color of the prey was not a relevant factor. E strike was predominant in the first predatory event in captivity. After habituation, S strike was predominant. Snakes may have a poor perception of the prey objects in captivity and adopt a strike strategy that assures the control of the prey. Also, the use of small prey subjects to ease feeding during adaptation to captivity may be less effective. Zoo Biol 20:399–406, 2001. © 2001 Wiley‐Liss, Inc.
Efficacy of levonorgestrel when administered as an irradiated, slow‐release injectable matrix for feline contraception
Authors: Looper Sheri , Anderson Gary , Sun Yichun , Shukla Atul , Lasley Bill 
Published: September 2002

AbstractReliable and safe methods of reversible contraception are needed for use in zoo felids. The efficacy of levonorgestrel (LNG) as a contraceptive, when delivered as a cesium‐irradiated, slow‐release, injectable matrix, was tested in domestic cats as a model for exotic cats. An increase (P= 0.0017) in body weight was observed in treated but not control queens (P= 0.2146). All control queens (n = 6), which received injections of matrix only, but none of the LNG‐treated queens (n = 6) became pregnant during the trial. Levonorgestrel was effective in preventing pregnancy for at least 36 weeks after two injections of drug‐loaded formulations (40 mg/kg body weight), administered 68 days apart. Throughout the study, all control queens displayed luteal activity and fluctuating fecal estradiol concentrations, whereas the LNG‐treated queens displayed lower estradiol concentrations and no luteal activity after treatment. We conclude that LNG, when delivered as a cesium‐irradiated, slow‐release, injectable matrix, is an effective contraceptive in domestic cats, reducing follicular activity, and thus, preventing mating and luteal activity. Zoo Biol 20:407–421, 2001. © 2001 Wiley‐Liss, Inc.
Influence of group size and neonatal handling on growth rates, survival, and tameness of juvenile houbara bustards
Authors: van Heezik Yolanda , Seddon Philip J. 
Published: September 2002

AbstractThe influence of group size, sex, year, and environmental enrichment on growth of a large sample of captive‐bred houbara bustards was examined, as well as the influence of regular handling on survival. Growth rates of chicks kept in groups of eight were depressed compared with chicks in groups of five. Differences in growth rates between males and females were not significant at fledging (∼35 days), but were so by 80 days, although interindividual variation still precluded reliable sexing by body mass at this age. Growth rates varied between years, suggesting that management practices may affect growth, and potentially the reproductive performance of birds. Survival of birds receiving extra handling, mainly in the form of regular weighing, was significantly higher than that of birds receiving little handling. The effect of environmental enrichment on tameness was also assessed. Tameness is desirable in the captive flock, where stress is perceived as a major impediment to reproductive performance, preventing the successful collection of semen from males and insemination of females, delaying recruitment, and causing nonbreeding among both sexes. Extra handling and environmental enrichment was applied to a sample of chicks, and tameness of juveniles was assessed in a variety of ways (open field test, subjective assessments), but no significant difference was found between the enriched birds and a control group. The enrichment protocol might be improved by increasing the period of time during which birds were handled and associating handling with food rewards, although the time required to carry out such a protocol may be constrained when large numbers of chicks are produced. Zoo Biol 20:423–433, 2001. © 2001 Wiley‐Liss, Inc.
Nociceptor activation and protein extravasation induced by inflammatory mediators in human skin
Authors: Lischetzki Grischa , Rukwied Roman , Handwerker Hermann O. , Schmelz Martin 
Published: September 2002

Protein extravasation (PE) is known to play an important role in inflammatory conditions. In this study we used dermal microdialysis to apply inflammatory mediators (histamine, bradykinin, serotonin) to human skin. Locally induced PE was compared to pain ratings and axon reflex erythema measured simultaneously. Linear microdialysis capillaries (outer diameter 0.4 mm; cut‐off 3000 kDa) were inserted intracutaneously at a length of 1.5 cm in the volar forearm of healthy volunteers. The capillaries were perfused with Ringer's solution at a constant flow rate of 4 μ l/min. The perfusate was sampled at 15‐min intervals and was analysed for total protein concentration. After a baseline of 60 min, the perfusion was switched to inflammatory mediators for 30 min and then back to vehicle again. Sensations evoked by the stimulation were assessed on a visual analogue scale and visible axon reflex erythema was measured planimetrically.Dose‐dependent increases in PE could be assessed for all inflammatory mediators tested. Bradykinin (10–7M) induced a significant PE, whereas serotonin was effective only at a concentration of 10–3M. While serotonin in lower concentrations induced moderate burning pain and an axon reflex flare but no PE, bradykinin provoked PE without pain or axon reflex flare at a concentration of 10–7M. Application of histamine similarly evoked PE at lower concentrations as compared to the induction of itch sensation and axon reflex flare.It is concluded that there is no link between nociceptor activation and protein extravasation induced by inflammatory mediators in healthy human skin.
Population differences in von Willebrand factor levels affect the diagnosis of von Willebrand disease in African‐American women
Authors: Miller Connie H. , Dilley Anne , Richardson Lisa , Hooper W. Craig , Evatt Bruce L. 
Published: September 2002

AbstractDiagnosis of von Willebrand disease (vWD) is based on a panel of laboratory tests that measure the amount and function of von Willebrand factor (vWF). In population studies, vWF is higher in African Americans than Caucasians. Bleeding time, factor VIII activity (FVIII), vWF antigen (vWF:Ag), “vWF activity” ELISA (vWF:Act), ristocetin cofactor (vWF:RCof), and ristocetin‐induced platelet aggregation (RIPA) were measured on 123 women with menorrhagia and 123 randomly selected control women; 70 cases and 76 controls were African American. Among controls, African Americans had significantly higher levels of vWF:Ag (mean 120 vs. 102 U/dl, P = 0.017). Among all subjects, African Americans had higher levels of vWF:Ag (mean 123 vs. 103, P = 0.001), vWF:Act (mean 101 vs. 89, P = 0.006), and FVIII (mean 118 vs. 104, P = 0.008). VWF:RCof did not differ between races (93 vs. 94 U/dl). RIPA was reduced in African Americans (P < 0.0001). In both races, women with type O blood differed significantly from those with other ABO types in vWF:Ag, vWF:Act, FVIII, and vWF:RCof. Based on criteria of two or more tests below race‐ and ABO‐specific reference ranges, 6.5% of menorrhagia cases and 0.8% of controls were classified as having vWD, or its phenocopy. Among Caucasians, no controls and 7 cases (15.6%) were classified as affected, and in African Americans, 1 control (1.3%) and 1 case (1.4%) were so classified. Racial differences in vWF further complicate the issues surrounding diagnosis of vWD. The finding of increased vWF:Ag not accompanied by increased vWF:RCof has implications for understanding the structure‐function relationships of vWF. Am. J. Hematol. 67:125–129, 2001. Published 2001 Wiley‐Liss, Inc.
Oxygen saturation and heart rate in healthy school children and adolescents living at high altitude
Authors: Huicho L. , Pawson I.G. , León‐Velarde F. , Rivera‐Ch M. , Pacheco A. , Muro M. , Silva J. 
Published: September 2002

AbstractThis study was conducted to establish reference values for percent oxygen saturation of hemoglobin (SaO2, %) and heart rate (HR, bpm) in children living at high altitude (4,100 m) and to relate possible differences in the variables with ethnic origin. Healthy children from a mine‐located school (Tintaya, n = 417), a nearby school (Marquiri, n = 474), and a rural Andean community (Nuñoa, n = 373) were investigated. The samples included different ethnic combinations, with the Nuñoa children having a predominant Quechua ancestry. Mean SaO2 for all ages was substantially lower in all high altitude children compared to values considered normal for sea level. Among the three samples, SaO2 was higher (91.3 ± 2.7) and HR was lower (84.8 ± 13.6) in Nuñoa than in Tintaya (SaO2, 89.8 ± 2.5; HR, 91.7 ± 14.9) and Marquiri (SaO2, 89.6 ± 3.1; HR, 88.5 ± 12.9) (P < 0.05). There was no sex difference and only a weak age‐dependent trend for SaO2. Values considered abnormal at sea level were observed in all healthy high‐altitude children. Higher SaO2 and lower HR in Nuñoa children may suggest a better degree of acclimatization to altitude. Am. J. Hum. Biol. 13:761–770, 2001. © 2001 Wiley‐Liss, Inc.
Genetic relationships between Amerindian populations of Argentina
Authors: Goicoechea A.S. , Carnese F.R. , Dejean C. , Avena S.A. , Weimer T.A. , Franco M.H.L.P. , Callegari‐Jacques S.M. , Estalote A.C. , Simões M.L.M.S. , Palatnik M. , Salzano Francisco M. 
Published: September 2002

AbstractA total of 495 individuals from five different Argentinian tribes was examined for variation in 23 blood group and protein genetic systems, and the results were integrated with previous data on some of these systems. These tribes generally present RH ∗︁ R1, PGM1 ∗︁ 1, and ACP ∗︁ A frequencies lower and RH ∗︁ R2, ESD ∗︁ 1, and GLO ∗︁ 1 prevalences higher than those observed in other South American Indian groups. Earlier studies with mitochondrial DNA showed that haplogroup A was present in low frequencies in these tribes, but haplogroup B showed a high prevalence among the Mataco. Average heterozygosities are very similar in the five tribes, while estimates of non‐Indian ancestry are generally low. Both the blood group and protein, as well as the mtDNA data sets, divide the five tribes into two groups, and the relationships obtained with the blood group and protein systems are exactly those expected on the basis of geography and language. However, the topology obtained with the mtDNA results was different, possibly due to sampling effects or diverse patterns of exchange between the groups related to sex. Am J Phys Anthropol 115:133–143, 2001. © 2001 Wiley‐Liss, Inc.