bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modular Palladium Bipyrazoles for the Isomerization of Allylbenzenes – Mechanistic Considerations and Insights into Catalyst Design and Activity, Role of Solvent, and Additive Effects
Authors: Spallek Markus J. , Stockinger Skrollan , Goddard Richard , Trapp Oliver 
Published: May 2012

AbstractThe catalytic activity of novel bidentate N,N‐chelated palladium complexes derived from electron excessive, backbone fused 3,3′‐bipyrazoles in the selective isomerization of terminal arylpropenoids and 1‐alkenes is described. The catalysts are easily modified by appropriate wing tip substitution, while maintaining the same bulky, rigid unreactive aliphatic backbone. Eleven novel palladium complexes with different electronic and steric properties were investigated. Their performance in the palladium(II)‐catalyzed isomerization of a series of substituted allylbenzenes was evaluated in terms of electronic as well as steric effects. Besides the clear finding of a general trend towards higher catalyst activity with more electron‐donating properties of the coordinated N,N‐bidentate ligands, we found that the catalytic process strongly depends on the choice of solvents and additives. Extensive solvent screening revealed that reactions run best in a 2:1 toluene‐methanol mixture, with the alcohol employed being a crucial factor in terms of electronic and steric factors. A reaction mechanism involving a hydride addition–elimination mechanism starting with a palladium hydride species generated in situ in alcoholic solutions, as corroborated by experiments using deuterium labeled allylbenzene, seems to be most likely. The proposed mechanism is also supported by the observed reaction rate orders of κobs[cat.]≈1 (0.94), κobs [substrate]=0.20→1.0 (t→∞) and κobs [methanol]=−0.51 for the isomerization of allylbenzene. Furthermore, the influence of acid and base, as well as the role of the halide coordinated to the catalyst, are discussed. The system catalyzes the isomerization of allylbenzenes very efficiently yielding high E:Z selectivities under very mild conditions (room temperature) and at low catalyst loadings of 1 mol% palladium even in unpurified solvents. The integrity and stability of the catalyst system were confirmed by multiple addition reaction cycles, successive filtration and isolation experiments, and the lack of palladium black formation.
Teleparallel gauge theory of gravity
Authors: Maluf J.W. , Faria F.F. 
Published: May 2012

AbstractIn this work a tetrad theory of gravity, invariant under conformal transformations, is investigated. The action of the theory is similar to the action of Maxwell's electromagnetism. The role of the electromagnetic gauge potential is played by the trace of the torsion tensor of the Weitzenböck spacetime. It is shown that all static, spherically symmetric space‐times, are solutions of the vacuum field equations. However, by fixing the gauge in the linearized form of the vacuum field equations, the usual Newtonian limit for the gravitational field is obtained.
Comparative study of the influence of active groups of chitosan derivatives on antifungal activity
Authors: Guo Zhanyong , Ren Jianming , Dong Fang , Wang Gang , Li Pengcheng 
Published: May 2012

AbstractIn this study, series of chitosan derivatives containing active groups were synthesized and evaluated for their antifungal activity against three crop‐threatening fungi, Fusarium oxysporum. f. sp. Vasinfectum, Alternaria solani, and Valsa mali. Schiff bases of carboxymethyl chitosan (As: 2‐(2‐hydroxy‐5‐nitrobenzylideneamino)‐6‐carboxymethyl chitosan; Bs: 2‐(2‐hydroxyl‐5‐chlorobenzaldimino)‐6‐carboxymethyl chitosan), N‐substituted carboxymethyl chitosan (An: 2‐(2‐hydroxyl‐5‐nitrobenzylamino)‐6‐carboxymethyl chitosan; Bn: 2‐(2‐hydroxyl‐5‐chlorobenzylamino)‐6‐carboxymethyl chitosan) and 2‐urea‐carboxymethyl chitosan (Au: 2‐(2‐nitrophenylurea)‐6‐carboxymethyl chitosan; Bu: 2‐(2‐chlorophenylurea)‐6‐carboxymethyl chitosan) were synthesized, and their antifungal activity was comparatively studied by hypha measurement in vitro, respectively. Results obtained from this study revealed that the active groups combined with Schiff bases functional groups (CN) could strengthen the antifungal activity most effectively among the compounds studied in this work. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Effects of two types of clay on physical and mechanical properties of poly(lactic acid)/wood flour composites at various wood flour contents
Authors: Liu Ru , Cao Jinzhen , Luo Shupin , Wang Xing 
Published: May 2012

AbstractTo investigate the effects of two types of clay, namely, Na‐montmorillonite (Na‐MMT) and organic‐montmorillonite (OMMT), on poly(lactic acid) (PLA)/wood flour (WF) composites, some physical and mechanical properties including the water sorption, thickness swelling, flexural modulus of rupture (MOR), and modulus of elasticity (MOE) of PLA/WF composites at different WF contents of 0, 20, 40, and 60 wt% were tested in this study. The results showed that: (1) the 24 h water uptake and thickness swelling increased and the flexural MOR and crystallinity decreased with the increasing WF content, whereas the flexural MOE of the composites increased with WF content up to 40 wt% but decreased sharply at WF content of 60 wt%; (2) the addition of Na‐MMT slightly increased the 24 h water uptake as well as the thickness swelling rate below 40 wt%, whereas OMMT reduced the thickness swelling at higher WF contents (40, 60 wt%) although it showed little effect on 24 h water uptake; (3) both Na‐MMT and OMMT could improve the flexural MOR and MOE of PLA/WF composite at WF contents below 40 wt%, and OMMT resulted in more obvious improvement than Na‐MMT. However, they both showed negative effect at WF content of 60 wt%; (4) XRD and FT‐Raman analysis suggested that clays would be attached more on the surface of the WF rather than diffused in the PLA matrix at a higher WF content (60 wt%); (5) SEM analysis proved that the interfacial adhesion of PLA and WF became poorer at WF content above 40 wt%, whereas it could be improved by OMMT modified. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Physical and thermal mechanical properties of corn starch/LDPE composites
Authors: Oromiehie A. R. , lari T. Taherzadeh , Rabiee A. 
Published: May 2012

AbstractThe potential of biodegradable polymers has long been recognized. In this work, composites of low density polyethylene (LDPE) and low density polyethylene/thermoplastic starch (LDPE/TPS) at different ratios of TPS (40%‐60% w/w) were prepared in internal mixer. Polyethylene‐grafted maleic anhydride (PE‐g‐MA) at 3 wt % was used as coupling agent. Chemical reactions between functional groups of composite components were studied and confirmed by Fourier transforms infrared (FTIR) spectroscopy. The morphology of film surfaces was studied using scanning electron microscopy. The physical, mechanical, and dynamic‐mechanical thermal analyses of LDPE/TPS composites were evaluated. The FTIR results showed transmission peak at 1642 cm−1, which is the result of chemical reaction between the hydroxyl groups of starch and anhydride groups of coupling agent. This verifies the presence of the carboxylate group due to the formation of ester bonding. The results showed that the water absorption and density of composite films increased by increasing the starch content in LDPE/TPS composites. The tensile strength and elongation at break decreased by increasing the starch level in the composites, but the young's modulus increased. The morphological studies showed that the biodegradability of composites increased by increasing the starch content and the results was confirmed by weight loss in buring the samples in wet soil during time intervals. The dynamic mechanical thermal analyzer thermograms showed that there are two relaxation temperature peaks. The amplitude of peaks increased by increasing the starch content from 40 to 60% probably due to increasing amorphous phase of composite. The starch was uniformly distributed throughout the LDPE polymer matrix and compatible and biodegradable composites were formed. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Effect of UV absorbers and hindered amine light stabilizers on the photodegradation of ethylene–octene copolymer
Authors: Liu Zhongyang , Chen Shuangjun , Zhang Jun 
Published: May 2012

AbstractThe photodegradation behavior of ethylene–octene copolymer (EOC) and EOC stabilized with UV stabilizers (Tinuvin 326, Chimassorb 81, Tinuvin 770 and Chimassorb 944) were investigated by the digital photography, color difference, gel content, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and mechanical tests. The results revealed that EOC exhibited a very poor photostability, whose performances were sharply reduced with increasing the irradiation time. The photodegradation products consisted of the carbonyl, hydroxyl and vinyl groups. The additives all showed an excellent photostabilizing effect, which effectively inhibited the gel formation and the chain photooxidation. The photostabilizing efficiency of these UV stabilizers could be ranked as Tinuvin 326 < Chimassorb 81 < Tinuvin 770 and Chimassorb 944. The secondary crystallization behavior was strongly affected by the annealing and chain scission. The chain scission, rather than the annealing, played a greater role in the secondary crystallization of the chain segments. And the serious chain scission could improve the mobility of the chain segments, which sharply promoted their crystallizability. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Simple Analogues of Qinghaosu (Artemisinin)
Authors: Li Yun , Hao Hong‐Dong , Wittlin Sergio , Wu Yikang 
Published: May 2012

AbstractA series of 1,2,4‐trioxanes were synthesized in which the key peroxy bonds were installed through a molybdenum‐catalyzed perhydrolysis of the epoxy rings. A core structure was identified that may serve as a promising lead structure for further investigations because of its high antimalarial activity (comparable to that of artesunate and chloroquine), apparent potential for scale‐up and derivatization, and facile monitoring/tracing by using UV light.
Emotions, Risk Perceptions, and Precautionary Behavior Under the Threat of Terror Attacks: A Field Study Among Israeli College Students
Authors: Rosenboim Mosi , Benzion Uri , Shahrabani Shosh , Shavit Tal 
Published: May 2012

AbstractThe current study uses the unique data from a natural experiment conducted in a college located in southern Israel that was exposed to rocket attacks in 2008. The study examines the relationships between the negative emotions, the perceptions of risk to oneself, the precautionary actions, and the intentions of 290 students who were exposed to terror attacks while on campus. In addition, we compared the emotions, the risk perceptions, and the precautionary behavior between the two groups: those who lived within the range of the rockets and were also exposed to rocket attacks at home and those who lived outside the range of the rockets. The results show that the risk perceptions were affected mainly by the emotion of fear while the students were on campus. In particular, fearful people became more pessimistic about their general and personal risks from terror but not about routine risks. The results also reveal that those who lived outside the rocket area (and had less or no experience with terror attacks) were more likely to take precautionary actions during their stay in the campus and were more pessimistic about continuing their studies in college in the coming year than those living in the area, who had more experience with terror attacks. Copyright © 2011 John Wiley & Sons, Ltd.
Discovery of Small‐Molecule Interleukin‐2 Inhibitors from a DNA‐Encoded Chemical Library
Authors: Leimbacher Markus , Zhang Yixin , Mannocci Luca , Stravs Michael , Geppert Tim , Scheuermann Jörg , Schneider Gisbert , Neri Dario 
Published: May 2012

AbstractLibraries of chemical compounds individually coupled to encoding DNA tags (DNA‐encoded chemical libraries) hold promise to facilitate exceptionally efficient ligand discovery. We constructed a high‐quality DNA‐encoded chemical library comprising 30 000 drug‐like compounds; this was screened in 170 different affinity capture experiments. High‐throughput sequencing allowed the evaluation of 120 million DNA codes for a systematic analysis of selection strategies and statistically robust identification of binding molecules. Selections performed against the tumor‐associated antigen carbonic anhydrase IX (CA IX) and the pro‐inflammatory cytokine interleukin‐2 (IL‐2) yielded potent inhibitors with exquisite target specificity. The binding mode of the revealed pharmacophore against IL‐2 was confirmed by molecular docking. Our findings suggest that DNA‐encoded chemical libraries allow the facile identification of drug‐like ligands principally to any protein of choice, including molecules capable of disrupting high‐affinity protein–protein interactions.
Influence of Drying and Calcination on Remaining Amount and Immobile Character of Titanium on Titanium‐pillared Montmorillonite
Authors: Zhao Chuan , Wang Xiaoqun , Du Shanyi 
Published: May 2012

AbstractRemove of titanium (Ti) from titanium‐pillared montmorillont (TIPM) is not expected during its application as adsorbent and photocatalyst, etc. But studies on immobilization of Ti on TIPM are seldom reported. In this work, TIPM was synthesized from TiCl4 and Na+‐montmorillont (Na+‐MMT). Then the prepared TIPM was heated at different temperatures (100, 240 and 450°C) to yield three TIPM samples (TIPM1, TIPM2, and TIPM3). Inductively coupled plasma optical emission spectrometer (ICP‐OES) was used to determine the effect of heating temperature on the remaining amount of Ti on TIPMs. A two‐step treatment method which is often used in the pretreatment and application of TIPM was developed to investigate the immobile character of Ti on TIPMs. X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FT‐IR), N2 adsorption/desorption isotherm, thermogravimetric analysis and differential scanning calorimetry (TG‐DSC) were also used to characterize TIPMs before and after the treatment. The results show that with an increase in heating temperature, the amount of Ti species remained on TIPM decreases gradually and Ti immobilization is strengthened on TIPM. For TIPM3, less than 2% Ti is removed from TIPM3 after the treatment required to simulate the practical conditions of TIPM in its application, while those of TIPM1 and TIPM2 are 6.6% and 8.4%, respectively. The reason may be that when TIPM is heated, Ti species intercalated into MMT become chemically bonded with the framework of MMT and partially migrate into the layer structure, which make Ti immobile on TIPM firmly during the treatment process.
Smoking Status on Outcomes After Percutaneous Coronary Intervention
Authors: Chen Tao , Li Wei , Wang Yang , Xu Bo , Guo Jin 
Published: May 2012

AbstractBackground:The effect of smoking on prognosis among patients undergoing percutaneous coronary intervention (PCI) is controversial, and data on the importance of smoking cessation or reductions were lacking.Hypothesis:Smoking cessation or reductions could reduce the risk of adverse outcomes in patient after PCI.Methods:There were 19 506 consecutive patients who had undergone successful PCI between April 2004 and January 2010 followed. Extensive data, including self‐reported smoking habits, were obtained at baseline and during follow‐up.Results:Compared with post‐PCI quitters and persistent smokers, the nonsmokers and pre‐PCI quitters were older and had a higher prevalence of comorbid factors such as hypertension and impaired left ventricle function. The adjusted hazard ratios for mortality were 2.52 (95% confidence interval [CI]: 1.92–3.30) for nonsmokers, 0.52 (95% CI: 0.32–0.84) for pre‐PCI quitters, and 0.11 (95% CI: 0.06–0.22) for post‐PCI quitters, compared to persistent smokers. With respect to additional revascularizations, a higher risk was observed among the quitters (1.70 [95% CI: 1.40–2.08] for pre‐PCI quitters and 1.59 [95% CI: 1.36–1.85] for post‐PCI quitters) as well as the nonsmokers (1.40 [95% CI: 1.20–1.64]). Among persistent smokers, each reduction of 5 cigarettes/day was associated with a 72% decline in mortality risk (P < 0.001) but did not reach statistical significant for repeated revascularizations (0.80 [95% CI: 0.46–1.37], P = 0.4132).Conclusions:Despite a higher risk of revascularization, the cessation of smoking either before or after PCI is beneficial in all‐cause mortality. The apparent smoker's paradox may be explained by the differences in baseline risk or the reduced sensitivity to adverse outcomes as well as the reluctance to seek medical help among smokers.This study received an unrestricted grant from Pfizer Investment Co., China. The authors have no other funding, financial relationships, or conflicts of interest to disclose.
Development of multiplex PCR system with 15 X‐STR loci and genetic analysis in three nationality populations from China
Authors: Liu Qiu‐Ling , Lu De‐Jian , Quan Li , Chen Ye‐Fei , Shen Min , Zhao Hu 
Published: May 2012

The aim of this study is to develop a new multiplex PCR system that simultaneously amplifies the 15 X‐chromosome short tandem repeats (X‐STRs) loci in the same PCR reaction, and to obtain the 15 X‐STR loci database in three nationality populations from China. This multiplex system includes DXS7133, DXS6801, DXS981, DXS6809, DXS7424, DXS6789, DXS9898, DXS7132, GATA165B12, DXS101, DXS10075, DXS6800, GATA31E08, DXS10074, and DXS10079, which were successfully analyzed on 1251 DNA samples (670 males and 581 females) from Guangdong Han population, Xinjiang Uigur and Kazakh. The allele frequencies and mutation rates of the 15 loci were investigated, and the allele frequency distribution among different populations was compared. A total of 6–17 alleles for each locus were observed and altogether 170 alleles for all the selected loci were found. Thirteen cases with mutation of the above loci were detected in 11 850 meioses. Pairwise comparisons of the allele frequencies distribution showed significant differences in most loci among different populations. The results indicate that this multiplex system may provide high polymorphism information for kinship testing and relationship investigations, and it is necessary to gain allele frequency and mutation rate of different population for forensic application.
De Liliifloris Notulae 9. The only hitherto known Spiloxene species (Hypoxidaceae) from Namibia is a new species, Spiloxene etesionamibensis, and a new Spiloxene species from Namaqualand (Northern Cape), S. namaquana
Authors: Müller‐Doblies Ute , Ackermann Markus , Weigend Maximilian , Müller‐Doblies Dietrich 
Published: May 2012

AbstractThe only Namibian species of Spiloxene is described and illustrated by drawings and photos as Spiloxene etesionamibensis U.Müll.‐Doblies, Mark.Ackermann, Weigend &. D.Müll.‐Doblies. It was hitherto misinterpreted as Spiloxene scullyi (Baker) Garside in Sölch & Roessler (1969) in Merxmüller's Prodromus einer Flora von Südwestafrika, but its closest ally is S. flaccida (Nel) Garside, found in the Western and the Eastern Cape. Spiloxene etesionamibensis, which was found independently by Giess & Merxmüller and by Müller‐Doblies, is only known from two or three independent collections from a single locality. S. scullyi is no longer known from Namibia.In addition to the eight Spiloxene species already known from the Northern Cape Spiloxene namaquana U.Müll.‐Doblies, Mark.Ackermann, Weigend & D.Müll.‐Doblies is described and illustrated by drawings and photos. Its closest ally is Spiloxene trifurcillata (Nel) Fourc. from the Eastern Cape.For Spiloxene namaquana the morphological analysis of the branching pattern of an annual shoot taken in 1988 in the field is evaluated by a longitudinal and a horizontal diagram with explanatory remarks. The unusual innovation system of extreme anisoiteration is discussed.On Map 1 the quarter degree squares of the type localities (± only known localities) of both species is given. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of age on genetic influence on bone loss over 17 years in women: The Healthy Ageing Twin Study (HATS)
Authors: Moayyeri Alireza , Hammond Christopher J , Hart Deborah J , Spector Timothy D 
Published: May 2012

Abstract
The rate of bone loss varies across the aging period via multiple complex mechanisms. Therefore, the role of genetic factors on bone loss may also change similarly. In this study, we investigated the effect of age on the genetic component of bone loss in a large twin-based longitudinal study. During 17 years of follow-up in TwinsUK and Healthy Ageing Twin Study (HATS), 15,491 hip and lumbar spine dual-energy X-ray absorptiometry (DXA) scans were performed in 7056 twins. Out of these subjects, 2716 female twins aged &gt;35 years with at least two scans separated for &gt;4 years (mean follow-up 9.7 years) were included in this analysis. We used a mixed-effects random-coefficients regression model to predict hip and spine bone mineral density (BMD) values for exact ages of 40, 45, 50, 55, 60, 65, 70, 75, and 80 years, with adjustment for baseline age, weight, height, and duration of hormone replacement therapy. We then estimated heritability of the changes in BMD measures between these age ranges. Heritability estimates for cross-sectional hip and spine BMD were high (ranging between 69% and 88%) at different ages. Heritability of change of BMD was lower and more variable, generally ranging from 0% to 40% for hip and 0% to 70% for spine; between age 40 and 45 years genetic factors explained 39.9% (95% confidence interval [CI], 25%–53%) of variance of BMD loss for total hip, 46.4% (95% CI, 32%–58%) for femoral neck, and 69.5% (95% CI, 59%–77%) for lumbar spine. These estimates decreased with increasing age, and there appeared to be no heritability of BMD changes after the age of 65 years. There was some evidence at the spine for shared genetic effects between cross-sectional and longitudinal BMD. Whereas genetic factors appear to have an important role in bone loss in early postmenopausal women, nongenetic mechanisms become more important determinants of bone loss with advanced age. © 2012 American Society for Bone and Mineral Research.
The Role of Posttraumatic Stress and Problem Alcohol Involvement in University Academic Performance
Authors: Bachrach Rachel L. , Read Jennifer P. 
Published: May 2012

ObjectiveThe present study examines how Posttraumatic Stress Disorder (PTSD) during the first year of university affects academic performance and whether alcohol behavior mediates the relationship between PTSD and poor academic outcomes.MethodUniversity students (N = 1,002; 65% female; Mage = 18.11) completed a baseline web survey, and 5 subsequent surveys throughout freshman year assessing variables of interest.ResultsMediation analyses were not significant; however, students who developed PTSD had a lower grade point average and experienced more alcohol consequences by the end of freshman year. Unremitted PTSD and alcohol consequences were associated with leaving university by year's end.ConclusionsFindings suggest that assessment of trauma‐related symptoms and alcohol behavior might benefit interventions aimed at students with academic difficulties. © 2012 Wiley Periodicals, Inc. J. Clin. Psychol. 68:843‐859, 2012
Prenatal sonographic diagnosis of mature renal teratoma: A case report
Authors: Yang Fan , Yang Taizhu , Luo Hong , Chen Huijiao , Yao Jin , Song Bin 
Published: May 2012

AbstractRenal teratoma is an extremely rare condition found in adolescents and young adults. Here, we report a case in which renal teratoma was diagnosed by fetal ultrasound examination. To our knowledge, this is the first report to describe the imaging manifestation of renal teratoma in prenatal diagnosis.© 2012 Wiley Periodicals, Inc. J Clin Ultrasound, 2013