bluuebunny/crossref_metadata_2025_split huggingface dataset:
Syntheses of semiconductor nanoparticles using single‐molecular precursors
Authors: Pickett Nigel L. , O’Brien Paul 
Published: September 2002

AbstractMethods for the preparation of II‐VI, III‐V, and II‐V as well as other compound semiconductor nanoparticles using main group single‐molecular precursors have been developed. The work involves the design and synthesis of compounds containing all the elements required within the desired nanoparticulate material. Precursors are tailored to give reproducible, clean decomposition at moderate temperatures, leading to high quality, defect free, mono‐dispersed nanoparticles. In this article we cover key aspects of precursor and nanoparticle synthesis. One of the more successful and reproducible series of single‐source precursors used, and the one on which we have concentrated our research efforts, is the bis(dialkyldithio‐/diseleno‐carbamato)cadmium(II)/zinc(II) compounds, M(E2CNR2)2 (M = Zn or Cd, E = S or Se, and R = alkyl) for the preparation of chalcogenide nanoparticulate materials. Preliminary mechanistic studies suggest that the precursor to nanoparticle deposition route is strongly influenced by the alkyl substituent groups present, and may well determine the phase and quality of the final metal chalcogenide nanoparticles produced. Herein we discuss the synthesis of semiconductor nanoparticles using such single‐molecular precursors. © 2001 John Wiley & Sons, Inc. and The Japan Chemical Journal Forum Chem Rec 1:467–479, 2001
Weak interactions and molecular recognition in systems involving electron transfer proteins
Authors: Hirota Shun , Yamauchi Osamu 
Published: September 2002

AbstractElectrostatic interactions and other weak interactions between amino acid side chains on protein surfaces play important roles in molecular recognition, and the mechanism of their intermolecular interactions has gained much interest. We established that charged peptides are useful for investigating the molecular recognition character of proteins and their molecular interaction induced structural changes. Positively charged lysine peptides competitively inhibited electron transfer from reduced cytochrome f (cyt f) or cytochrome c (cyt c) to oxidized plastocyanin (PC), due to neutralization of the negatively charged site of PC by formation of PC–lysine peptide complexes. Lysine peptides also inhibited electron transfer from cyt c to cytochrome c peroxidase. Likewise, negatively charged aspartic acid peptides interacted with the positively charged sites of cyt f and cyt c, and competitively inhibited electron transfer from reduced cyt f or cyt c to oxidized PC and from [Fe(CN)6]4– to oxidized cyt c. Changes in the geometry and a shift to a higher redox potential of the active site Cu of PC on oligolysine binding were detected by spectroscopic and electrochemical measurements, owing to the absence of absorption in the visible region for lysine peptides. Structural and redox potential changes were also observed for cyt f and cyt c by interaction with aspartic acid peptides. ©2001 John Wiley & Sons, Inc. and The Japan Chemical Journal Forum Chem Rec 1:290–299, 2001
Science enrichment programs for gifted high school girls and boys: Predictors of program impact on science confidence and motivation*
Authors: Stake Jayne E. , Mares Kenneth R. 
Published: September 2002

AbstractThe impact of two science enrichment programs on the science attitudes of 330 gifted high school students was evaluated using a multimethod, multiperspective approach that provided a more comprehensive evaluation of program impact on science attitudes than did previous assessments of science programs. Although pre–post comparisons did not indicate positive impact on science attitudes, other measures provided strong evidence of program effectiveness. Program benefits were greater among girls, those who had more supportive families and teachers, and those who entered the programs with greater general confidence in their abilities. Implications for science enrichment programs and their evaluation are discussed. © 2001 John Wiley & Sons, Inc. J Res Sci Teach 38: 1065–1088, 2001
The black–white “achievement gap” as a perennial challenge of urban science education: A sociocultural and historical overview with implications for research and practice*
Authors: Norman Obed , Ault Charles R. , Bentz Bonnie , Meskimen Lloyd 
Published: September 2002

AbstractA perennial challenge for urban education in the United States is finding effective ways to address the academic achievement gap between African American and White students. There is widespread and justified concern about the persistence of this achievement gap. In fact, historical evidence suggests that this achievement gap has existed at various times for groups other than African Americans. What conditions prevailed when this achievement gap existed for these other groups? Conversely, under what conditions did the gap diminish and eventually disappear for these groups? This article explores how sociocultural factors involved in the manifestation and eventual disappearance of the gap for these groups may shed some light on how to address the achievement gap for African American students in urban science classrooms. Our conclusion is that the sociocultural position of groups is crucial to understanding and interpreting the scholastic performance of students from various backgrounds. We argue for a research framework and the exploration of research questions incorporating insights from Ogbu's cultural, ecological theory, as well as goal theory, and identity theory. We present these as theories that essentially focus on student responses to societal disparities. Our ultimate goal is to define the problem more clearly and contribute to the development of research‐based classroom practices that will be effective in reducing and eventually eliminating the achievement gap. We identify the many gaps in society and the schools that need to be addressed in order to find effective solutions to the problem of the achievement gap. Finally, we propose that by understanding the genesis of the gap and developing strategies to harness the students' responses to societal disparities, learning can be maximized and the achievement gap can be significantly reduced, if not eliminated entirely, in urban science classrooms. © 2001 John Wiley & Sons, Inc. J Res Sci Teach 38: 1101–1114, 2001
Case‐based pedagogy as a context for collaborative inquiry in the Philippines
Authors: Arellano Elvira L. , Barcenal Tessie L. , Bilbao Purita P. , Castellano Merilin A. , Nichols Sharon , Tippins Deborah J. 
Published: September 2002

AbstractThe purpose of this study was to investigate the potential for using case‐based pedagogy as a context for collaborative inquiry into the teaching and learning of elementary science. The context for this study was the elementary science teacher preparation program at West Visayas State University on the the island of Panay in Iloilo City, the Philippines. In this context, triple linguistic conventions involving the interactions of the local Ilonggo dialect, the national language of Philipino (predominantly Tagalog) and English create unique challenges for science teachers. Participants in the study included six elementary student teachers, their respective critic teachers and a research team composed of four Filipino and two U.S. science teacher educators. Two teacher‐generated case narratives serve as the centerpiece for deliberation, around which we highlight key tensions that reflect both the struggles and positive aspects of teacher learning that took place. Theoretical perspectives drawn from assumptions underlying the use of case‐based pedagogy and scholarship surrounding the community metaphor as a referent for science education curriculum inquiry influenced our understanding of tensions at the intersection of re‐presentation of science, authority of knowledge, and professional practice, at the intersection of not shared language, explicit moral codes, and indigenization, and at the intersection of identity and dilemmas in science teaching. Implications of this study are discussed with respect to the building of science teacher learning communities in both local and global contexts of reform. © 2001 John Wiley & Sons, Inc. J Res Sci Teach 38: 502–528, 2001
Interpretive investigation of the science‐related career decisions of three African‐American college students
Authors: Lewis Bradford F. , Collins Angelo 
Published: September 2002

AbstractReports published since 1977 indicate that African Americans are underrepresented among Ph.D.‐holding scientists. Although researchers have identified numerous factors that correlate with career choice, they have failed to address students' reasons for choosing or not choosing science and science‐related careers. This study examines the career decisions of three African‐American college students. All three students began college aspiring toward science‐related careers. However, by the end of data collection only one student was working toward a science‐related career. Data were collected by means of eight, open‐ended, 1‐hour interviews conducted over a period of 6 months. Findings indicate that students' interest in a science‐related career is directly related to the degree to which they perceive that career as being supportive of deep‐seated life goals; and that a deeper view of the nature of science better enables students to perceive a science‐related career as supportive of life goals. © 2001 John Wiley & Sons, Inc. J Res Sci Teach 38: 599–621, 2001
Maternal diabetes: An independent risk factor for major cardiovascular malformations with increased mortality of affected infants
Authors: Loffredo Christopher A. , Wilson P. David , Ferencz Charlotte 
Published: September 2002

AbstractBackgroundIntensive medical care of women with diabetes has reduced their risks of bearing infants with congenital anomalies. To assess the preventive potential of preconceptional care, the data of a population‐based study of cardiovascular malformations (CVM) were analyzed to determine the morphogenetic specificity of maternal diabetes risks, the morbidity and mortality of the infants, and maternal characteristics that might affect these risks.MethodsThe Baltimore‐Washington Infant Study was a case‐control study (1981‐1989) that included all live born infants with confirmed CVM; control infants were a representative sample of the birth cohort. A questionnaire administered in home visits recorded parental information on social, medical, occupational, and environmental factors. For these analyses of preconceptional diabetes risks, the case group excluded chromosomal and mendelian disorders and was divided into 3 developmental categories and 12 diagnostic groups.ResultsPreconceptional maternal diabetes was strongly associated with CVM of early embryonic origin (odds ratio [OR] = 4.7, 95% confidence interval [CI] 2.8–7.9) and with cardiomyopathy (OR = 15.1, 95% CI 5.5–41.3), but not with obstructive and shunting defects (OR = 1.4, 95% CI 0.7–3.0). There was heterogeneity within these developmental categories: among laterality defects, diabetes was associated only with cardiovisceral and atrioventricular discordance (OR = 10.0, 95% CI 3.7–27.0); among outflow tract anomalies, the risk was strongly associated with normally related great arteries (OR = 6.6, 95% CI 3.2–13.3) but not with simple transpositions; and among atrioventricular septal defects, diabetes was associated with the complete but not with the partial forms (OR = 22.8, 95% CI 7.4–70.5). The association in early CVM was strongest among infants with multisystem, predominantly VACTERL, anomalies. All‐cause mortality of infants with CVM was 39% among those with diabetic mothers and 17.8% in those with nondiabetic mothers. Deceased infants of diabetic mothers were also more likely to have extracardiac anomalies (P = 0.041), to be born prematurely (P = 0.007), and to have low birth weight (P = 0.011). Multivariate analyses of maternal factors revealed no significant confounders of the diabetes associations.ConclusionsThe evidence of diabetes‐induced major cardiac defects is of urgent clinical significance. The effectiveness of early preconceptional care in the prevention of congenital anomalies has been demonstrated repeatedly. Teratology 64:98–106, 2001. © 2001 Wiley‐Liss, Inc.
Inhibitors of choline uptake and metabolism cause developmental abnormalities in neurulating mouse embryos
Authors: Fisher Melanie C. , Zeisel Steven H. , Mar Mei‐Heng , Sadler T. W. 
Published: September 2002

AbstractBackgroundCholine is an essential nutrient in methylation, acetylcholine and phospholipid biosynthesis, and in cell signaling. The demand by an embryo or fetus for choline may place a pregnant woman and, subsequently, the developing conceptus at risk for choline deficiency.MethodsTo determine whether a disruption in choline uptake and metabolism results in developmental abnormalities, early somite staged mouse embryos were exposed in vitro to either an inhibitor of choline uptake and metabolism, 2‐dimethylaminoethanol (DMAE), or an inhibitor of phosphatidylcholine synthesis, 1‐O‐octadecyl‐2‐O‐methyl‐rac‐glycero‐3‐phosphocholine (ET‐18‐OCH3). Cell death following inhibitor exposure was investigated with LysoTracker Red and histology.ResultsEmbryos exposed to 250–750 μM DMAE for 26 hr developed craniofacial hypoplasia and open neural tube defects in the forebrain, midbrain, and hindbrain regions. Embryos exposed to 125–275 μM ET‐18‐OCH3 exhibited similar defects or expansion of the brain vesicles. ET‐18‐OCH3‐affected embryos also had a distended neural tube at the posterior neuropore. Embryonic growth was reduced in embryos treated with either DMAE (375, 500, and 750 μM) or ET‐18‐OCH3 (200 and 275 μM). Whole mount staining with LysoTracker Red and histological sections showed increased areas of cell death in embryos treated with 275 μM ET‐18‐OCH3 for 6 hr, but there was no evidence of cell death in DMAE‐exposed embryos.ConclusionsInhibition of choline uptake and metabolism during neurulation results in growth retardation and developmental defects that affect the neural tube and face. Teratology 64:114–122, 2001. © 2001 Wiley‐Liss, Inc.
Cytosolic redox metabolism in aerobic chemostat cultures of Saccharomyces cerevisiae
Authors: Påhlman Inga‐Lill , Gustafsson Lena , Rigoulet Michel , Larsson Christer 
Published: September 2002

AbstractCytosolic redox balance has to be maintained in order to allow an enduring cellular metabolism. In other words, NADH generated in the cytosol has to be re‐oxidized back to NAD+. Aerobically this can be done by respiratory oxidation of cytosolic NADH. However, NADH is unable to cross the mitochondrial inner membrane and mechanisms are required for conveying cytosolic NADH to the mitochondrial electron transport chain. At least two such systems have proved to be functional in S. cerevisiae, the external NADH dehydrogenase (Luttik et al., 1998; Small and McAlister‐Henn, 1998) and the G3P shuttle (Larsson et al., 1998). The aim of this investigation was to study the regulation and performance of these two systems in a wild‐type strain of S. cerevisiae using aerobic glucose‐ and nitrogen‐limited chemostat cultures. The rate of cytosolic NADH formation was calculated and as expected there was a continuous increase with increasing dilution rate. However, measurements of enzyme activities and respiratory activity on isolated mitochondria revealed a diminishing capacity at elevated dilution rates for both the external NADH dehydrogenase and the G3P shuttle. This suggests that adjustment of in vivo activities of these systems to proper levels is not achieved by changes in amount of protein but rather by, for example, activation/inhibition of existing enzymes. Adenine nucleotides are well‐known allosteric regulators and both the external NADH and the G3P shuttle were sensitive to inhibition by ATP. The most severe inhibition was probably on the G3P shuttle, since one of its member proteins, Gpdp, turned out to be exceptionally sensitive to ATP. The external NADH dehydrogenase is suggested as the main system employed for oxidation of cytosolic NADH. The G3P shuttle is proposed to be of some importance at low growth rates and perhaps its real significance is only expressed during starvation conditions. Copyright © 2001 John Wiley & Sons, Ltd.
Pichia pastoris Pex14p, a phosphorylated peroxisomal membrane protein, is part of a PTS–receptor docking complex and interacts with many peroxins
Authors: Johnson Monique A. , Snyder William B. , Lin Cereghino Joan , Veenhuis Marten , Subramani Suresh , Cregg James M. 
Published: September 2002

AbstractThe peroxisomal protein import machinery plays a central role in the assembly of this organelle in all eukaryotes. Genes encoding components of this machinery, termed peroxins or Pex proteins, have been isolated and characterized in several yeast species and in mammals, including humans. Here we report on one of these components, Pex14p, from the methylotrophic yeast Pichia pastoris. Work in other organisms has shown that Pex14p is located on the cytoplasmic surface of the peroxisomal membrane and binds peroxisomal targeting signal (PTS) receptors carrying proteins bound for the peroxisomal matrix, results that have led to the hypothesis that Pex14p is a receptor‐docking protein. P. pastoris Pex14p (PpPex14p) behaves like an integral membrane protein, with its C‐terminus exposed on the cytosolic side of the peroxisomal membrane. PpPex14p complexes with many peroxins, including Pex3p (Snyder et al., 1999b), Pex5p, Pex7p, Pex13p, Pex17p, itself, and a previously unreported peroxin, Pex8p. A portion of Pex14p is phosphorylated, but both phosphorylated and unphosphorylated forms of Pex14p interact with several peroxins. The interactions between Pex14p and other peroxins provide clues regarding the function of Pex14p in peroxisomal protein import. Copyright © 2001 John Wiley & Sons, Ltd.
Carnitine‐dependent metabolic activities in Saccharomyces cerevisiae: three carnitine acetyltransferases are essential in a carnitine‐dependent strain
Authors: Swiegers Jan H. , Dippenaar Nola , Pretorius Isak S. , Bauer Florian F. 
Published: September 2002

AbstractL‐Carnitine is required for the transfer of activated acyl‐groups across intracellular membranes in eukaryotic organisms. In Saccharomyces cerevisiae, peroxisomal membranes are impermeable to acetyl‐CoA, which is produced in the peroxisome when cells are grown on fatty acids as carbon source. In a reversible reaction catalysed by carnitine acetyltransferases (CATs), activated acetyl groups are transferred to carnitine to form acetylcarnitine which can be shuttled across membranes. Here we describe a mutant selection strategy that specifically selects for mutants affected in carnitine‐dependent metabolic activities. Complementation of three of these mutants resulted in the cloning of three CAT encoding genes: CAT2, coding for the carnitine acetyltransferase associated with the peroxisomes and the mitochondria; YAT1, coding for the carnitine acetyltransferase, which is presumably associated with the outer mitochondrial membrane, and YER024w (YAT2), which encodes a third, previously unidentified carnitine acetyltransferase. The data also show that (a) L‐carnitine and all three CATs are essential for growth on non‐fermentable carbon sources in a strain with a disrupted CIT2 gene; (b) Yat2p contributes significantly to total CAT activity when cells are grown on ethanol; and that (c) the carnitine‐dependent transfer of activated acetyl groups plays a more important role in cellular processes than previously realised. Copyright © 2001 John Wiley & Sons, Ltd.
A hedonic price analysis of thoroughbred broodmare characteristics
Authors: Neibergs J. Shannon 
Published: September 2002

AbstractThoroughbred broodmares are the primary input in the foal production process. Breeders need to make informed broodmare investment decisions, since substantial financial and genetic risks are associated with overvaluing a broodmare's productive capacity. Each broodmare represents a unique combination of breeding, racing, and genetic characteristics. This study estimates the marginal values of broodmare characteristics. Results identify large price differentials for broodmares that have won or produced graded stakes race winners. The analysis provides information for marketing, accounting and management decisions. [EconLit Citation: Q130]. © 2001 John Wiley & Sons, Inc.
Methods for estimation of bone marrow plasma cell involvement in myeloma: Predictive value for response and survival in patients undergoing autologous stem cell transplantation
Authors: Rajkumar S. Vincent , Fonseca Rafael , Dispenzieri Angela , Lacy Martha Q. , Lust John A. , Witzig Thomas E. , Therneau Terry M. , Kyle Robert A. , Greipp Philip R. , Gertz Morie A. 
Published: September 2002

AbstractIn myeloma, the bone marrow plasma cell percentage (BMPC%) is usually estimated independently on the aspirate, core biopsy, and plasma cell labeling index (PCLI) samples. This study was done to determine which of the 3 individual estimates correlates best with complete response (CR) and survival. Seventy‐five consecutive patients who underwent SCT for relapsed myeloma were studied. The median BMPC% on the marrow aspirate, core biopsy, and PCLI studies were 20, 25, and 20, respectively. There was a significant correlation between the three methods, ρ > 0.65,P< 0.001. However, in 8% of patients the BMPC% was different by an absolute value of 50% between methods. No individual method was predictive for CR. However, the highest estimate of the BMPC% among the three methods was a significant predictor of CR (P= 0.02). Survival following SCT was longer among patients with a low BMPC% (≤60) by the PCLI method compared to those with higher values, median survival 23 versus 7 months, respectively,P= 0.02. PFS was also different, with survival times of 11 and 5 months, respectively,P= 0.003. Similar results were obtained when the highest estimate of the BMPC% was used in survival analysis (P= 0.02 and 0.004, respectively). Statistical significance was lower when the BMPC% on the aspirate or biopsy used in survival analysis. Compared to any individual method of estimating BMPC%, the highest estimate of the BMPC% is the best predictor of CR in myeloma. It is also prognostic for poor survival and PFS following SCT for myeloma. We recommend that all three methods of estimating BMPC% be routinely performed and that the highest value be used for prognostic purposes. Am. J. Hematol. 68:269–275, 2001. © 2001 Wiley‐Liss, Inc.