bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study on surface structure and composition of the smaller size organic nanotube and its supermolecule thin films using AFM/force curve method
Authors: Zhu C. F. , Xu Q. M. , Zhou C. Q. , Yin S. X. , Shang G. Y. , Wang C. , Liu C. Q. , Zhang R. B. 
Published: September 2002

AbstractThe surface microstructures of three kinds of polymer thin films (ladderlike polypropyl‐silsesquioxane, organic nanotube and its supermolecule) are studied by atomic force microscopy (AFM) at room temperature in air. The new information then is used for investigation of the microstructure of the polymer from the statistics data of distribution of the adhesion force on the thin films. The statistics of adhesion force distribution agree well with the morphology of AFM. There is good agreement between the experimental results, the configuration models from molecular mechanics calculation and the designed molecular models. We have successfully prepared the organic nanotube and its supermolecular thin film. The liquid crystal molecule has been inserted into the nanotube to form a supermolecule. The statistics results of distribution of the adhesion force would provide interesting data for correctly defining the microstructure of the polymer thin films. We demonstrate that AFM together with molecular mechanics calculation and statistics of the adhesion force distribution would be a good method for studying the microstructure and properties of new functional materials. Copyright © 2001 John Wiley & Sons, Ltd.
Structures of surface‐ and bulk‐dispersion phases of NiO/Al2O3
Authors: Cai Xiaohai , Ren Zhiguo , Hu Tiandou , Xie Youchang 
Published: September 2002

AbstractThe structural features of surface‐dispersion and bulk‐dispersion states of NiO on /in γ‐Al2O3have been studied by x‐ray absorption fine structure (XAFS) in combination with x‐ray diffraction (XRD) and XPS. The results obtained from XRD and XAFS show that surface and bulk dispersions of Ni2+ions need different conditions and have different diffraction features and different coordination structures. In both the surface‐dispersion phase and the solid solution, Ni2+ions seem to prefer to keep the coordination mode in NiO, which is quite different from that in the stoichiometric spinel. The Ni/Al intensity ratios of XPS at different etching depths of samples have a maximum and the distribution of Ni2+ions in the solid solution is not homogeneous. Both it and the coordination features provide evidence of the transition process of dispersing from surface to bulk. Copyright © 2001 John Wiley & Sons, Ltd.
Interface diffusion and reaction between Ti layer and Si3N4/Si substrate
Authors: Zhu Yongfa , Wang Li , Yao Wenqing , Cao Lili 
Published: September 2002

AbstractA Ti layer of thickness 270 nm was deposited successfully on the surface of Si3N4/Si substrate using the d.c. sputtering technique. Auger electron spectroscopy (AES) analysis indicates that the Ti layer reduced the native SiO2 layer that existed on the surface of the Si3N4 film to form TiOx and Si species at the interface during deposition. The interface diffusion and reaction between the Ti layer and Si3N4/Si substrate was promoted significantly by annealing treatments in the temperature range 300–700 °C in a high vacuum. At temperatures below 600 °C, only very little silicide formed. With increasing annealing temperature, TiSi species formed rapidly. When the temperature reached 700 °C, both TiSi and TiSi2 species formed in the interlayer. The formation of TiSi and TiSi2 species was governed mainly by the interface reaction when the annealing time was short. Silicon in the interlayer mainly came from the Si3N4 layer at low temperature or a short annealing time, otherwise it mainly came from the depletion of Si substrate at high temperature or a long annealing time. Copyright © 2001 John Wiley & Sons, Ltd.
High‐temperature nitridation and oxidation of Ti‐based alloys
Authors: Thongtem Somchai , Thongtem Titipun , McNallan Michael 
Published: September 2002

AbstractHigh‐temperature nitridation in nitrogen followed by oxidation in air of Ti–(0.5–20.0)wt.%V and Ti–36.0wt.%Al were studied at 1100–1300 K. The oxidation rate of Ti–(0.5–20.0)wt.%V over 5 h continuously increased with the concentration of vanadium up to 10.0 wt.% V. Above this level, the oxidation rate tended to be constant when the experimental time was sufficient. However, the lowest oxidation rate was found in the case of Ti–36.0wt.%Al. Nitridation can effectively protect the alloys against oxidation. The alloys were characterized by x‐ray diffraction and the results were in agreement with those characterized by a CHNS/O analyser. In addition, the characteristics of the alloys revealed by SEM micrographs were consistent with the oxidation rates in air. Copyright © 2001 John Wiley & Sons, Ltd.
Monte Carlo simulation of low‐energy electron trajectories and energy loss in ZnS phosphor powders
Authors: Greeff A. P. , Swart H. C. 
Published: September 2002

AbstractDuring electron beam irradiation of ZnS phosphor powders, a non‐luminescent ZnO layer is formed on the powder due to electron‐beam‐stimulated surface reactions. As the thickness of the oxide layer increases, the energy loss in the ZnS bulk decreases with a subsequent degradation in cathodoluminescence. Using the Monte Carlo technique, the trajectories of low‐energy electrons were simulated in a ZnS phosphor powder with a ZnO overlayer of varying thickness based on recent models describing the energy loss and scattering angles of low‐energy electrons in a solid. A diffusion interface between the ZnO layer and ZnS bulk was simulated by varying the concentration of O and S atoms in the interface. Modelling the interface in this way describes the electron trajectories and energy loss in the interface region, because a sharp interface between two dissimilar layers very seldom exists. In the energy‐loss profiles the transition between ZnO and ZnS corresponds to a sharp increase in energy loss due to the increased rate of energy loss of electrons in ZnS. The diffusion interface has a smoothing effect on this sudden increase. From the electron trajectory data and corresponding energy loss, energy loss profiles were determined indicating the cumulative distribution of all the electron energy losses as a function of the interaction volume depth and thickness of the ZnO layer. When a distribution of incident angles is used, the profile differs from the typical energy‐loss profile seen at normal incident angles. As the thickness of the ZnO layer increases, the total energy loss in the solid decreases due to the increase in the backscattering coefficient of electrons in ZnO. Copyright © 2001 John Wiley & Sons, Ltd.
Causes and prevention of photochemical reduction of hexavalent chromium during x‐ray photoelectron spectroscopy
Authors: Kagwade Sanjay V. , Clayton Clive R. , Halada Gary P. 
Published: September 2002

AbstractWe report on the photoreduction of hexavalent chromium during exposure to soft x‐rays used in x‐ray photoelectron spectroscopy (XPS). Photoreduction of hexavalent chromium to the tetravalent state in both CrO3 and K2CrO4 was found to involve hydrocarbons adsorbed onto the sample surface during rough pumping with a rotary pump during sample entry. When rough pumping was performed by a Venturi pump and a sorption pump, no photoreduction was observed over a period of 6 h of exposure to soft x‐rays. We also observed that Cr(IV) was stable under soft x‐ray radiation. In the presence of water vapor in the vacuum chamber, Cr(IV) was chemically reduced to Cr(III). The findings of this study bring into question the applicability of current models explaining the photoreduction of high‐valent chromium oxides during XPS, and are also of general interest. Copyright © 2001 John Wiley & Sons, Ltd.
Automated structural analysis of SCR‐style software requirements specifications using PVS
Authors: Kim Taeho , Cha Sungdeok 
Published: September 2002

AbstractThe importance of effective requirements analysis techniques cannot be overemphasized when developing software requiring high levels of assurance. Requirements analysis can be largely classified as either structural or functional. The former investigates whether definitions and uses of variables and functions are consistent, while the latter addresses whether requirements accurately reflect users' needs. Verification of structural properties for large and complex software requirements is often repetitive, especially if requirements are subject to frequent changes. While inspection has been successfully applied to many industrial applications, the authors found inspection to be ineffective when reviewing requirements to find errors violating structural properties. Moreover, current tools used in requirements engineering provide only limited support in automatically enforcing structural correctness of the requirements. Such experience has motivated research to automate straightforward but tedious activities.This paper demonstrates that a theorem prover, PVS (Prototype Verification System), is useful in automatically verifying structural correctness of software requirements specifications written in SCR (Software Cost Reduction)‐style. Requirements are automatically translated into a semantically equivalent PVS specification. Users need not be experts in formal methods or power users of PVS. Structural properties to be proved are expressed in PVS theorems, and the PVS proof commands are used to carry out the proof automatically. Since these properties are application independent, the same verification procedure can be applied to requirements of various software systems. Copyright © 2001 John Wiley & Sons, Ltd.
Test case selection strategies based on Boolean specifications‡
Authors: Chen T. Y. , Lau M. F. 
Published: September 2002

AbstractThis paper considers test case selection for programs whose specifications are expressed by Boolean algebra. The approach is to select test cases based on Boolean specifications. Three test case selection strategies are proposed that aim at the detection of theliteral insertion faultand theliteral reference fault. Although theMAX‐Bstrategy proposed by Weyukeret al.guarantees detection of these types of faults, the proposed strategies are more effective in the sense that the derived test cases form a subset of those selected by theMAX‐Bstrategy. Copyright © 2001 John Wiley & Sons, Ltd.
No significant increase in chromosome aberrations and sister chromatid exchanges in cultured human lymphocytes treated with spiramycin
Authors: Rencüzoğulları Eyyüp , İla Hasan Basri , Topaktaş Mehmet , Kayraldız Ahmet , Budak Songül , Arslan Mehmet 
Published: September 2002

AbstractIn this study, the chromosomal aberrations (CAs) and sister chromatid exchanges (SCEs) were investigated in human lymphocytes treated with spiramycin antibiotic (trade name, rovamycin). Spiramycin did not induce the CAs and SCEs, and also did not decrease the mitotic index (MI). However, spiramycin decreased the replication index (RI) only at 48 h treatment times. Teratogenesis Carcinog. Mutagen. 22:51–58, 2002. © 2002 Wiley‐Liss, Inc.
The biosynthesis of acarbose and validamycin
Authors: Mahmud Taifo , Lee Sungsook , Floss Heinz G. 
Published: September 2002

AbstractThe studies reported here have established the biosynthetic origin of the mC7N units of acarbose and validamycin from sedo‐heptulose 7‐phosphate, and have identified 2‐epi‐5‐epi‐valiolone as the initial cyclization product. The deoxyhexose moiety of acarbose arises from glucose with deoxythymidyl‐diphospho‐4‐keto‐6‐deoxy‐D‐glucose (dTDP‐4‐keto‐6‐deoxy‐D‐glucose) as a proximate intermediate. However, despite the identical origin of the aminocyclitol moieties in acarbose and validamycin A, the pathways of their formation seem to be substantially different. Validamycin A formation involves a number of discrete ketocyclitol intermediates, 5‐epi‐valiolone, valienone, and validone, whereas no free intermediates have been identified on the pathway from 2‐epi‐5‐epi‐valiolone to the pseudodisaccharide moiety of acarbose. The stage is now set for unraveling the mechanism or mechanisms by which the two components of the pseudodisaccharide moieties of acarbose and validamycin are uniquely coupled to each other via a nitrogen bridge. © 2001 John Wiley & Sons, Inc. and The Japan Chemical Journal Forum Chem Rec 1: 300–310, 2001
Asymmetric autocatalysis and the origin of chiral homogeneity in organic compounds
Authors: Soai Kenso , Sato Itaru , Shibata Takanori 
Published: September 2002

AbstractThe discovery and development of asymmetric autocatalysis, in which the structures of the chiral catalyst and the chiral product are the same, are described. Chiral 5‐pyrimidyl, 3‐quinolyl, and 5‐carbamoyl‐3‐pyridyl alkanols act as highly enantioselective asymmetric autocatalysts in the enantioselective addition of diisopropylzinc to the corresponding aldehydes, such as pyrimidine‐5‐carbaldehyde. 2‐Alkynyl‐5‐pyrimidyl alkanol with an enantiomeric excess (ee) of >99.5% automultiplies practically perfectly as an asymmetric autocatalyst in a yield of >99% and >99.5% ee. Asymmetric autocatalysis with an amplification of ee has thus been realized. Consecutive asymmetric autocatalysis starting with chiral 2‐alkynylpyrimidyl alkanol of only 0.6% ee amplifies its ee significantly, and yields itself as the product with >99.5% ee. The reaction of pyrimidine‐5‐carbaldehyde and diisopropylzinc in the presence of chiral initiators with low ee’s, such as secondary alcohol, amine, carboxylic acid, mono‐substituted [2.2]paracyclophane, and chiral primary alcohols due to deuterium substitution, regulates the absolute configuration of the resulting pyrimidyl alkanols, and the ee of the resulting pyrimidyl alkanol is much higher than that of the chiral initiator. Leucine and [6]helicene with very low ee’s, which are known to be induced by circularly polarized light (CPL), also serve as chiral initiators to produce pyrimidyl alkanol with higher ee’s. Overall, the process represents the first correlation between the chirality of CPL and an organic compound with very high ee. Chiral inorganic crystals, such as quartz and sodium chlorate, act as chiral inducers in the asymmetric autocatalysis of pyrimidyl alkanol. The process correlates for the first time ever the chirality of inorganic crystals with an organic compound with very high ee. © 2001 John Wiley & Sons, Inc. and The Japan Chemical Journal Forum Chem Rec 1:321–332, 2001
Same school, separate worlds: A sociocultural study of identity, resistance, and negotiation in a rural, lower track science classroom
Authors: Gilbert Andrew , Yerrick Randy 
Published: September 2002

AbstractThis ethnographic study examined how rural, lower track, underrepresented students made sense of their place in school and what role school science played in their cultural reproduction. The objectives of the study were to identify key components of science classroom discourse, analyze means of negotiating these components, and explicate participants' beliefs and roles in defining microcultural identities specific to rural, underrepresented school contexts. Eight students and their teacher participated in this study, which drew heavily upon teacher and student revoicing of common events. Results showed that the quality of science instruction was subverted through a process of negotiation between students and teachers in the context of low expectations and the school culture. Implications for research and practice are discussed. © 2001 John Wiley & Sons, Inc. J Res Sci Teach 38: 574–598, 2001
Effects of cadmium on formation of the ventral body wall in chick embryos and their prevention by zinc pretreatment
Authors: Thompson Jennifer , Bannigan John 
Published: September 2002

AbstractBackgroundCadmium (Cd) is an established experimental teratogen whose effects can be reversed by pretreatment with zinc. Mesodermal development is a frequently reported target for Cd teratogenicity. The aim of this study was to examine the mechanisms of Cd induced body wall defects in chick embryos.MethodsChick embryos in shell‐less culture were treated with 50 μl of cadmium acetate (8.9 × 10−5 M Cd2+) at 60‐hr incubation (H.‐H. stages 16–17). Controls received equimolar sodium acetate. Other embryos were treated with various concentrations of zinc acetate and then with Cd or NaAc 1 hrs later. Development was evaluated 48 hrs later. Resin‐embedded 1‐μm sections were examined at earlier stages.ResultsCd caused embryolethality (35%), ventral body wall defect with malpositioned lower limbs (40%), and weight reduction in survivors. After 4‐hr treatment with Cd, breakdown of junctions between peridermal cells with rounding up and desquamation occurred. Shape changes were also seen in the basal layer of the ectoderm. At 4 hr, cell death was evident in lateral plate mesoderm, somites, and neuroepithelium; the lateral plate mesoderm began to grow dorsally, carrying the attached limb buds with it. Zn pretreatment protected against the lethal, teratogenic, and growth‐retarding effects of Cd, as well as ectodermal changes and cell death.ConclusionsCd disrupts peridermal cell adhesion and induces cell death in the mesoderm. This may result in abnormal growth of lateral plate mesoderm and in a body wall defect. Zn pretreatment prevents both the gross teratogenic effects and the cellular changes, most likely by competition with Cd. Teratology 64:87–97, 2001. © 2001 Wiley‐Liss, Inc.
Emphasis on Financial vs Nonfinancial Criteria in Employer Benefits’ Measurements
Authors: Pfeffer Jeffrey , Olsen Esther , Singer Sara J. 
Published: January 2025

ImportanceFew studies have examined the extent to which employers emphasize financial over nonfinancial criteria in measurement, reporting, and decision-making about health care benefits.ObjectiveTo measure and identify factors associated with financial over nonfinancial emphasis in employer decision-making about health benefits.Design, Setting, and ParticipantsA survey was administered to a nationally representative sample of US employers to assess the extent of employers’ emphasis on benefits plans’ costs over member experience, access to care, and equity, and on financial vs other considerations when choosing third-party benefits administrators. The sample included in-company human resources administrators from randomly selected nongovernmental organizations with at least 50 employees. The survey was administered in 2 waves: May 2022 to July 2022 and November 2022 to April 2023.ExposureThe survey included 41 multipart questions capturing information about the respondent, company, company interactions with benefits consulting firms and benefits administrators, and company approach to managing employee health benefits.Main Outcomes and MeasuresMain outcomes were proportion of financially oriented measures that internal benefits administrators and external benefits consultants use and importance of financial vs other factors in companies’ choice of third-party administrators.ResultsOf 1159 companies sampled, 251 (22%) responded; 30 with less than 50 employees were excluded. Of the 221 remaining companies, 147 (67%) used a benefits consulting firm. The companies and their benefits consultants focused on financial over nonfinancial performance dimensions in decision-making. While 125 companies (74%) tracked trends in health benefits costs and 109 (64%) tracked spending on the highest cost cases, only 14 (8%) tracked time employees spent having questions answered, and 12 (7%) tracked how often employees delayed receiving care because of an insurance company’s actions. This financial focus was largely independent of organizational characteristics and other potential explanatory factors. Of 37 paired differences comparisons in the proportion of financial vs nonfinancial items, only 6 proportions (16%) differed significantly, with differences in proportions of 0.22 or less.Conclusions and RelevanceIn this survey study, US employers emphasized financial over nonfinancial criteria in their measurement and decision-making about health benefits. To improve health plan performance, employer measurement and decision-making must emphasize both nonfinancial and financial criteria.
Adverse Prehospital Events and Outcomes After Traumatic Brain Injury
Authors: Maiga Amelia W. , Lin Hsing-Hua Sylvia , Wisniewski Stephen R. , Brown Joshua B. , Moore Ernest E. , Schreiber Martin A. , Joseph Bellal , Wilson Chad T. , Cotton Bryan A. , Ostermayer Daniel G. , Harbrecht Brian G. , Patel Mayur B. , Sperry Jason L. , Guyette Francis X. , Wang Henry E. 
Published: January 2025

ImportanceWhile national guidelines recommend avoidance of hypoxia, hypotension, and hypocarbia in the prehospital care of traumatic brain injury (TBI), limited data validate the association of these adverse physiologic events with TBI outcomes.ObjectiveTo validate the associations of prehospital hypoxia, hypotension, and hypocarbia with TBI outcomes in a US national trauma network.Design, Setting, and ParticipantsThis cohort study examined data from 8 level I trauma centers and their affiliated ground and air emergency medical services (EMS) agencies in the Linking Investigations in Trauma and Emergency Services (LITES) Network from January 1, 2017, to June 30, 2021. Adult patients (aged ≥18 years) with confirmed TBI (head Abbreviated Injury Score [AIS] of 1-6) and Injury Severity Score (ISS) of at least 9 were included. Interfacility transfers and patients who underwent prehospital cardiopulmonary resuscitation were excluded. Data were analyzed between April 20, 2022, and November 27, 2023.ExposuresAdverse prehospital TBI events, including hypoxia, hypotension, or hypocarbia.Main Outcomes and MeasuresThe primary outcomes were death in the emergency department (ED), hospital death, and unfavorable discharge disposition. Log-binomial regression models were used to estimate the association between adverse TBI events and outcomes, adjusting for sex, race and ethnicity, age, study site, transport mode, initial Glasgow Coma Scale, ISS, head AIS score, injury mechanism, and multiple trauma.ResultsThe analytic cohort included 14 994 patients (median [IQR] age, 47 [31-64] years; 71% male; median [IQR] head AIS, 3 [2-4]). Patients with adverse TBI events included 12% (1577 of 13 604) with hypoxia, 10% (1426 of 14 842) with hypotension, and 61% (650 of 1068) with hypocarbia among those with advanced airway management. Patient outcomes included 2% (259 of 14 939) who died in the ED, 12% (1764 of 14 623) who died in the hospital, and 25% (3705 of 14 623) with an unfavorable discharge disposition. Hypoxia (adjusted relative risk [ARR], 2.24; 95% CI, 1.69-2.97), hypotension (ARR, 2.05; 95% CI, 1.54-2.72), and hypocarbia (ARR, 7.99; 95% CI, 2.47-25.85) were associated with increased risks of ED death. Each adverse TBI event exposure was also associated with higher risks of hospital death and unfavorable discharge disposition.Conclusions and RelevanceIn this multicenter cohort study, prehospital hypoxia, hypotension, and hypocarbia were associated with poorer TBI outcomes. These results underscore the importance of optimal oxygenation, ventilation, and perfusion in prehospital TBI care.