bluuebunny/crossref_metadata_2025_split huggingface dataset:
Syntheses and structures of sulfilimine, sulfone diimine, and sulfoximine derivatives of a monocyclic thiophene, 3,4‐di‐tert‐butylthiophene
Authors: Nakayama Juzo , Otani Takashi , Sugihara Yoshiaki , Sano Yuki , Ishii Akihiko , Sakamoto Akira 
Published: September 2002

AbstractThe reaction of 3,4‐di‐tert‐butylthiophene (6a) with N‐[(p‐tolylsulfonyl)imino]‐phenyliodinane (TsN=IPh) in the presence of Cu(MeCN)4PF6 in MeCN at room temperature provided 3,4‐di‐tert‐butyl‐1‐[(p‐tolylsulfonyl)imino]‐1,1‐dihydrothiophene (3b),3,4‐di‐tert‐butyl‐1,1‐bis[(p‐tolylsulfonyl)imino]‐1,1‐dihydrothiophene (5a), and 1‐(p‐tolylsulfonyl)‐3,4‐di‐tert‐butylpyrrole (7a) as the principal products. The use of 20 molar amounts of 6a gave 3b in an increased yield of 61%. Treatment of 3,4‐di‐tert‐butylthiophene 1‐oxide (1a) with (CF3CO)2O or (CF3SO2)2O, followed by reactions with RSO2NH2, ROC(=O)NH2, or RCONH2, furnished a series of S‐imino derivatives (3b,c,e–h) of 6a, which carry an electron‐withdrawing substituent on the imino nitrogen atom. Treatment of the S‐imino derivative 3f (substituent on the nitrogen atom = COBu) with CF3CO2H gave an aminosulfonium salt (13), whose deprotonation led to the parent N‐unsubstituted 1‐imide derivative (3n). Treatment of 2,4‐di‐tert‐butylthiophene 1‐oxide (1b) with TsN=IPh in the presence of Cu(MeCN)4PF6 in MeCN at room temperature provided 2,4‐di‐tert‐butyl‐1‐[(p‐toluenesulfonyl)imino]‐1,1‐dihydrothiophene 1‐oxide (4e) in 81% yield. Hydrolysis of 4e by concentrated H2SO4 at room temperature furnished 2,4‐di‐tert‐butyl‐1‐imino‐1,1‐dihydrothiophene 1‐oxide (4f) in 89% yield. A pair of enantiomers of 4f were separated by high‐performance liquid chromatography (HPLC) on a chiral column, and their absolute configurations were determined by an X‐ray crystallographic analysis. Structures of sulfilimine, sulfone diimine, and sulfoximine derivatives of monocyclic thiophenes, obtained in these ways, are discussed based on spectroscopies (IR and 1H and 13C NMR) and X‐ray crystallographic analyses. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:333–348, 2001
Reinvestigation on the halogenation of 1,1,2,3,4,5‐hexaphenylstannole
Authors: Saito Masaichi , Haga Ryuta , Yoshioka Michikazu 
Published: September 2002

AbstractHalogenation of 1,1,2,3,4,5‐hexaphenylstannole was reinvestigated. Reaction of the stannole with 2 equiv. of bromine gave 1‐bromo‐4‐dibromophenylstannyl‐1,2,3,4‐tetraphenyl‐1,3‐butadiene. Reaction of the stannole with iodine gave similar results. Reaction of the stannole with 1 equiv. of bromine or iodine afforded 1‐halo‐4‐halodiphenylstannyl‐1,2,3,4‐tetraphenyl‐1,3‐butadiene, resulting from halogenation with the cleavage of the bond between tin and vinyl carbon. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:349–353, 2001
New construction of p‐tolylsulfonyl‐substituted naphthalenes by thermal and photochemical cyclization of 1‐aryl‐4‐(methylthio)‐2‐(p‐tolylsulfonyl)‐1,3‐butadienes
Authors: Matsumoto Shoji , Takahashi Shinjiro , Ogura Katsuyuki 
Published: September 2002

AbstractTransformation of 4‐(methylthio)‐1‐phenyl‐2‐(p‐tolylsulfonyl)‐1,3‐butadiene 1a was found to give 2‐(p‐tolylsulfonyl)naphthalene 3a either by the action of I2 in refluxing acetonitrile or by irradiation with a high‐pressure Hg lamp. An electron‐withdrawing group (p‐F or p‐CO2Me) on the phenyl ring retarded the thermal reaction, but the corresponding naphthalene derivative was efficiently produced by the photolysis in the presence of I2. The substituent effect of an electron‐donating methoxyl group is also reported. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:385–391, 2001
Preparation and 31P NMR study of some low‐coordinated organophosphorus compounds bearing the 2,4‐di‐t‐butyl‐6‐isopropylphenyl group
Authors: Toyota Kozo , Matsushita Yoshiaki , Shinohara Naoyuki , Yoshifuji Masaaki 
Published: September 2002

Abstract2‐Bromo‐1,5‐di‐t‐butyl‐3‐isopropyl‐benzene was prepared and converted to the 2,4‐di‐t‐butyl‐6‐isopropylphenyl‐substituted phosphonous dichloride, primary phosphine, diphosphenes, and dithioxophosphorane. The 31P NMR chemical shifts of these compounds are close to those of 2,4‐di‐t‐butyl‐6‐methylphenyl substituted congeners. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:418–423, 2001
Preparation and reactions of water stable hypervalent 10‐Sn‐5 allyl ate complexes
Authors: Kojima Satoshi , Kondoh Fumihiro , Kawakami Jun‐ya , Yamamoto Yohsuke , Akiba Kin‐ya 
Published: September 2002

AbstractHypervalent 10‐Sn‐5 allyl and crotyl tin ate complexes bearing Martin ligands were prepared and found to be surprisingly stable in water. These compounds were found to react with aldehydes in the presence of weak Lewis acids such as LiBr to give the corresponding homoallyl alcohols. Product analysis of the reaction of the crotyl compounds indicated that the reaction occurred via a cyclic transition state unlike an acyclic transition state operative for widely utilized allyltrialkyltin reagents that are of ordinary valency. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:425–430, 2001
The performance of sample selection estimators to control for attrition bias
Authors: Grasdal Astrid 
Published: September 2002

AbstractSample attrition is a potential source of selection bias in experimental, as well as non‐experimental programme evaluation. For labour market outcomes, such as employment status and earnings, missing data problems caused by attrition can be circumvented by the collection of follow‐up data from administrative registers. For most non‐labour market outcomes, however, investigators must rely on participants' willingness to co‐operate in keeping detailed follow‐up records and statistical correction procedures to identify and adjust for attrition bias. This paper combines survey and register data from a Norwegian randomized field trial to evaluate the performance of parametric and semi‐parametric sample selection estimators commonly used to correct for attrition bias. The considered estimators work well in terms of producing point estimates of treatment effects close to the experimental benchmark estimates. Results are sensitive to exclusion restrictions. The analysis also demonstrates an inherent paradox in the ‘common support’ approach, which prescribes exclusion from the analysis of observations outside of common support for the selection probability. The more important treatment status is as a determinant of attrition, the larger is the proportion of treated with support for the selection probability outside the range, for which comparison with untreated counterparts is possible. Copyright © 2001 John Wiley & Sons, Ltd.
Neuroleptic malignant syndrome with olanzapine associated with severe hypernatremia
Authors: Arnaout M. Samir , Antun Fouad P. , Ashkar Khalil 
Published: September 2002

AbstractA 30‐year‐old white man with schizophrenia developed anorexia and nausea, and was admitted to hospital for confusion and delirium. He was on olanzapine, 10 days prior to admission. On admission, typical neuroleptic malignant syndrome (NMS) developed with elevated body temperature (39.7°C), obtundation, tremor, rigidity, diaphoresis, fluctuating pupillary diameter, tachycardia, labile hypertension, elevated serum creatine kinase and severe hypernatremia (190 meq/l). Olanzepine was stopped few days after admission to the hospital and the NMS manifestations resolved by hospital day 12. The patient had all of the major manifestations of NMS. There was no other likely explanation for his illness. This is the first case reported in which NMS was associated with olanzapine and extremely elevated levels of serum sodium. Copyright © 2001 John Wiley & Sons, Ltd.
Influence of reservoirs on solute transport: a regional‐scale approach
Authors: Kelly Valerie J. 
Published: September 2002

AbstractRegional transport of water and dissolved constituents through heavily regulated river systems is influenced by the presence of reservoirs. Analysis of seasonal patterns in solute fluxes for salinity and nutrients indicates that in‐reservoir processes within large storage reservoirs in the Rio Grande and Colorado basins (southwestern USA) are superimposed over the underlying watershed processes that predominate in relatively unregulated stream reaches. Connectivity of the aquatic system with the landscape is apparently disrupted by processes within the reservoir systems; these processes result in large changes in characteristics for solute transport that persist downstream in the absence of significant inputs. Additionally, reservoir processes may be linked for upstream/downstream reservoirs that are located relatively close in a series. In contrast, the regional effect of in‐reservoir processes is negligible for solute transport through run‐of‐river reservoirs in the lower Columbia River (northwestern USA). Published in 2001 by John Wiley & Sons, Ltd.
A conceptual model of preferential flow systems in forested hillslopes: evidence of self‐organization
Authors: Sidle Roy C. , Noguchi Shoji , Tsuboyama Yoshio , Laursen Karin 
Published: September 2002

AbstractPreferential flow paths are known to be important conduits of subsurface stormflow in forest hillslopes. Earlier research on preferential flow paths focused on vertical transport; however, lateral transport is also evident in steep forested slopes underlain by bedrock or till. Macropores consisting of decayed and live roots, subsurface erosion, surface bedrock fractures, and animal burrows form the basis of a ‘backbone’ for lateral preferential flow in such sites. Evidence from field studies in Japan indicates that although individual macropore segments are generally <0·5 m in length, they have a tendency to self‐organize into larger preferential flow systems as sites become wetter. Staining tests show clear evidence of interconnected macropore flow segments, including: flow within decayed root channels and subsurface erosion cavities; flow in small depressions of the bedrock substrate; fracture flow in weathered bedrock; exchange between macropores and mesopores; and flow at the organic horizon–mineral soil interface and in buried pockets of organic material and loose soil. Here we develop a three‐dimensional model for preferential flow systems based on distributed attributes of macropores and potential connecting nodes (e.g. zones of loose soil and buried organic matter). We postulate that the spatially variable and non‐linear preferential flow response observed at our Japan field site, as well as at other sites, is attributed to discrete segments of macropores connecting at various nodes within the regolith. Each node is activated by local soil water conditions and is influenced strongly by soil depth, permeability, pore size, organic matter distribution, surface and substrate topography, and possibly momentum dissipation. This study represents the first attempt to characterize the spatially distributed nature of preferential flow paths at the hillslope scale and presents strong evidence that these networks exhibit complex system behaviour. Copyright © 2001 John Wiley & Sons, Ltd.
Hydrobiogeochemistry of forest ecosystems in Japan: major themes and research issues
Authors: Ohte Nobuhito , Tokuchi Naoko , Shibata Hideaki , Tsujimura Maki , Tanaka Tadashi , Mitchell Myron J. 
Published: September 2002

AbstractHydrobiogeochemical information on forested watersheds in the Japanese archipelago is reviewed to qualitatively summarize the major factors affecting the hydrology and biogeochemistry of this region. Major features that distinguish Japanese forest watersheds from those of north central Europe and the northeast United States generally include higher temperature, greater precipitation and steeper topography. There have been three major themes in hydrobiogeochemistry research on Japanese forest ecosystems: (1) investigations of nutrient cycles with particular emphasis on the establishment and maintenance of forest ecosystems; (2) evaluations of streamwater chemistry as an output from the forest ecosystem; and (3) hydrological studies using biogeochemical tracers. High precipitation inputs during the growing season affect the seasonality of the streamwater NO3− concentration, resulting in different temporal patterns than those generally found in north central Europe and the northeast United States. The high alkalinity and pH of Japanese surface waters is due to the rapid weathering of relatively young soils that are generated by steep hillslopes. Warm temperatures and elevated soil moisture enhance high rates of mineral weathering. Hydrological studies using biogeochemical tracers have shown that the steep topography contributes to the highly heterogeneous movement of water within Japanese catchments. Copyright © 2001 John Wiley & Sons, Ltd.
Evaluation of a reproductive toxicity assay using Xenopus laevis: boric acid, cadmium and ethylene glycol monomethyl ether
Authors: Fort Douglas J. , Stover Enos L. , Bantle John A. , Dumont James N. , Finch Robert A. 
Published: September 2002

AbstractCadmium (Cd), boric acid (BA) and ethylene glycol monomethyl ether (EGME) were evaluated for reproductive and developmental toxicity in Xenopus laevis. Eight reproductively mature adult male and eight superovulated female Xenopus laevis were exposed to at least five separate sublethal concentrations of each material via the culture water for a period of 30 days. Four respective pairs were mated and the offspring evaluated for developmental effects; an evaluation of reproductive status was performed on the remaining four specimens. Ovary pathology, oocyte count, oocyte maturity and maturation capacity (germinal vesicle breakdown, GVBD) and necrosis were evaluated in the female, whereas testis pathology, sperm count, dysmorphology and motility were studied in the male. Based on this assessment, each test material exerted reproductive toxicity in Xenopus laevis, but with varying potencies. Adult female exposure to Cd and EGME particularly, and to a lesser extent to BA, resulted in transgenerational toxicity to the developing progeny. Further, this model appears to be a useful tool in the initial assessment and prioritization of potential reproductive toxicants for further testing. Copyright © 2001 John Wiley & Sons, Ltd.
Comparison of the biomechanics and histology of two soft‐tissue fixators composed of bioabsorbable copolymers
Authors: Powers Dennis L. , Sonawala Mehul , Woolf Shane K. , An Yuehuei H. , Hawkins Richard , Pietrzak William S. 
Published: September 2002

AbstractThe purpose of this study was to assess the dynamic in vitro and in vivo characteristics of two different bioabsorbable copolymer soft‐tissue fixation devices and to determine their efficacy in reattaching soft tissue to bone. Suretac® fixators (Smith & Nephew/Acufex MicroSurgical Inc., Northwood, MA), made of polyglyconate (2:1 glycolic acid:trimethylene carbonate), and Pop Rivets® (Arthrotek, Warsaw, IN), made of LactoSorb® (82% poly L‐lactic acid, 18% polyglycolic acid), were anchored into synthetic bone, and their pull‐out strengths were evaluated. The devices were also evaluated with the use of an in vivo goat model in which the medial collateral ligament (MCL) was elevated from the tibia and directly reattached. In the in vitro biomechanical study, the Suretac® fixators had negligible strength remaining by four weeks, whereas the Pop Rivets® retained 50% of their strength at 4 weeks, 20% at 8 weeks, and negligible strength at 12 weeks. The in vivo strength of MCL repairs affected by each implant was not statistically different at any of the time points. Histologically, both implants were absorbed by 52 weeks, and there was no appreciable adverse tissue response. In conclusion, both copolymer fixators were found to be biocompatible. The Pop Rivet® fixators demonstrated in vivo performance comparable to the Suretac® fixators, although the Pop Rivets® retained strength longer in vitro. Our results suggest that both devices provide adequate strength of fixation before degrading to allow the healing soft tissues to reach or surpass their native strength. © 2001 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 58: 486–495, 2001
Epigallocatechin gallate protects U937 cells against nitric oxide‐induced cell cycle arrest and apoptosis
Authors: Kelly Melissa R. , Geigerman Cissy M. , Loo George 
Published: September 2002

AbstractIngesting phenolic phytochemicals in many plant products may promote health, but the effects of phenolic phytochemicals at the cellular level have not been fully examined. Thus, it was determined if the tea phenolic phytochemical, epigallocatechin gallate (EGCG), protects U937 human pro‐monocytic cells against the nitrogen free radical, nitric oxide (•NO). Cells were incubated for 4–6 h with 500 μM S‐nitrosoglutathione (GSNO), which generates •NO, but this did not induce single‐strand breaks in DNA. Nevertheless, 82 ± 4% of GSNO‐treated cells, compared to only 39 ± 1% of untreated cells, were arrested in the G1‐phase of the cell cycle. However, dosing the GSNO‐treated cells with 9, 14, or 18 μg/ml of EGCG resulted in only 74 ± 8%, 66 ± 1%, and 43 ± 3% of the cells, respectively, in the G1‐phase. Exposing cells to GSNO also resulted in the emergence of a sub‐G1 apoptotic cell population numbering 14 ± 3%, but only 5 ± 2%, 5 ± 1%, and 2 ± 0% upon dosing of the GSNO‐treated cells with 9, 14, and 18 μg/ml of EGCG, respectively. Furthermore, exposing cells to GSNO resulted in greater cell surface binding of annexin V‐FITC, but binding was 41–89% lower in GSNO‐treated cells dosed with EGCG. Collectively, these data suggest that •NO or downstream products induced cell cycle arrest and apoptosis that was not due to single‐strand breaks in DNA, and that EGCG scavenged cytotoxic •NO or downstream products, thus reducing the number of cells in a state of cell cycle arrest or apoptosis. J. Cell. Biochem. 81: 647–658, 2001. © 2001 Wiley‐Liss, Inc.
Evaluation of a knowledge‐based potential of mean force for scoring docked protein–ligand complexes
Authors: Nobeli Irene , Mitchell John B. O. , Alex Alexander , Thornton Janet M. 
Published: September 2002

AbstractThe Biomolecular Ligand Energy Evaluation Protocol (BLEEP) is a knowledge‐based potential derived from high‐resolution X‐ray structures of protein–ligand complexes. The performance of this potential in ranking the hypothetical structures resulting from a docking study has been evaluated using fifteen protein–ligand complexes from the Protein Data Bank. In the majority of complexes BLEEP was successful in identifying the native (experimental) binding mode or an alternative of low rms deviation (from the native) as the lowest in energy. Overall BLEEP is slightly better than the DOCK energy function in discriminating native‐like modes. Even when alternative binding modes rank lower than the native structure, a reasonable energy is assigned to the latter. Breaking down the BLEEP scores into the atom–atom contributions reveals that this type of potential is grossly dominated by longer range interactions (>5 Å), which makes it relatively insensitive to small local variations in the binding site. However, despite this limitation, the lack, at present, of accurate protein–ligand potentials means that BLEEP is a promising approach to improve the filtering of structures resulting from docking programs. Moreover, BLEEP should improve with the continuously increasing number of complexes available in the PDB. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 673–688, 2001
Reassociation of fragments using multicentered multipolar expansions: peptide junction treatments to investigate electrostatic properties of proteins
Authors: Dardenne L. E. , Werneck A. S. , Oliveira Neto M. , Bisch P. M. 
Published: September 2002

AbstractWe report an analysis of three schemes for fragment reassociation using multicentered multipolar expansions derived from ab initio quantum wave functions at the Hartree–Fock/6‐31G* LCAO level, two of them involving single‐bond partitioning in the peptide bond region, and the third one using a partially overlapping procedure based on a methodology proposed by Vigné‐Maeder21 (OME—overlap of multipolar expansions—reassociation method). The effects of different peptide junction treatments in the derivation of molecular electrostatic potentials and molecular electric fields of three peptide sequences are discussed. The results show that the OME reassociation method gives a better and a more homogeneous description of both the potential and the electric field than the other two treatments. We conclude that the OME method is the most indicated for studies involving electrostatic properties of proteins. Our results also indicate that the use of multicentered multipolar expansions coupled to the OME treatment is the best choice in protein studies including solvent effects using, for example, a continuum boundary method to solve the linearized Poisson–Boltzmann equation. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 689–701, 2001
Porosity and surface characteristics of activated carbons produced from waste tyre rubber
Authors: Miguel Guillermo San , Fowler Geoffrey D , Dall'Orso Marco , Sollars Christopher J 
Published: September 2002

AbstractWaste tyre rubber has proven to be a suitable precursor for the production of high quality activated carbons. The performance of these carbons in commercial applications such as water treatment or gas purification is highly dependent on their surface characteristics. This paper presents an in‐depth investigation on how production conditions may affect the yield and characteristics of activated carbons produced from tyre rubber. For this purpose, three tyre rubbers of different particle sizes were consecutively pyrolysed and then activated in a steam atmosphere at 925 °C using a laboratory‐scale rotary furnace. Activation was conducted at different intervals over 80–640 min to achieve different degrees of carbon burn‐off. The resulting carbons were analysed for their elemental composition, ash content and nitrogen gas adsorption characteristics. The BET and t‐plot models were used to investigate various aspects of their porosity and surface area characteristics. SEM analyses were also conducted for visual examination of the carbon surface. Results show that pyrolytic chars, essentially mesoporous materials, developed a very narrow microporosity during the initial stages of the activation process (up to 15–25 wt% burn‐off). Further activation resulted in the progressive enlargement of the average micropore width and a gradual development of the mesoporous structure. Total micropore volumes and BET surface areas increased continuously with the degree of activation to reach values up to 0.498 cm3g−1 and 1070 m2g−1 respectively, while external surface areas developed more rapidly at degrees of activation above 45 wt% burn‐off. Results presented in this work also illustrate that carbons produced from powdered rubber developed a narrower and more extensive porosity, both in the micropore and mesopore range, than those produced from rubber of a larger particle size.© 2001 Society of Chemical Industry
Hydrolysis of carboxymethylcellulose with mixtures of cellulase and β‐1,4‐glucosidase
Authors: Bravo V , Páez M P , El‐Hadj M Aoulad , Reyes A , García A I 
Published: September 2002

AbstractWe studied the hydrolysis of carboxymethylcellulose at 50 °C and pH 4.9 with a commercial preparation of cellulase (Celluclast) supplemented with a commercial β‐1,4‐glucosidase product (Novozym). The initial concentration of carboxymethylcellulose was varied between 2 and 12.5 kg m−3 for assays with Celluclast and two Novozym/Celluclast ratios (0.5 and 1). We determined the conversion to glucose and the overall conversion in terms of glucose equivalent. Conversion to glucose turned out to be directly proportional to the product of experimental time multiplied by the concentration of Celluclast and the constant of proportionality increased concomitantly with the concentration of Novozym. Overall conversion remained unaffected by the concentration of Novozym.© 2001 Society of Chemical Industry