bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of Isotactic–Heterotactic Stereoblock (Hard–Soft) Poly(lactide) with Tacticity Control through Immortal Coordination Polymerization
Authors: Zhao Wei , Wang Yang , Liu Xinli , Chen Xuesi , Cui Dongmei 
Published: July 2012

AbstractA one‐pot method for the preparation of a new family of PLA materials is reported that combines heterotactic (soft) and isotactic stereoblocks (hard). The ring‐opening polymerization of rac‐lactide with a salan–rare‐earth‐metal–alkyl complex in the presence of excess triethanolamine was performed in an immortal mode to give three‐armed heterotactic poly(lactide) (soft) with excellent end‐hydroxy fidelity. The in situ addition of a salen–aluminum–alkyl precursor to the above polymerization system under any monomer‐conversion conditions activated the “dormant” hydroxy‐ended PLA chains to propagate through the incorporation of the remaining rac‐lactide monomer, but with isospecific selectivity (hard). The resultant PLA had a three‐armed architecture with controlled molecular weight and extremely narrow molecular‐weight distribution (PDI<1.08). More strikingly, each side‐arm simultaneously possessed highly heterotactic (soft) and highly isotactic (hard) segments and the ratio of these two stereoregular sequences could be swiftly adjusted by tuning the addition time of the salen–aluminum–alkyl precursor to the polymerization system. Therefore, star‐shaped hard–soft stereoblock poly(lactide)s with various Pm values and crystallinity were achieved in a single reactor for the first time. This strategy should be applicable to the synthesis of a series of new types of stereoblock polyesters by using an immortal‐polymerization process and a proper choice of specific, selective metal‐based catalysts.
Good or Bad, We Want it Now: Fixed‐cost Present Bias for Gains and Losses Explains Magnitude Asymmetries in Intertemporal Choice
Authors: Hardisty David J. , Appelt Kirstin C. , Weber Elke U. 
Published: July 2012

ABSTRACTIntertemporal tradeoffs are ubiquitous in decision making, yet preferences for current versus future losses are rarely explored in empirical research. Whereas rational‐economic theory posits that neither outcome sign (gains vs. losses) nor outcome magnitude (small vs. large) should affect delay discount rates, both do, and moreover, they interact: in three studies, we show that whereas large gains are discounted less than small gains, large losses are discounted more than small losses. This interaction can be understood through a reconceptualization of fixed‐cost present bias, which has traditionally described a psychological preference for immediate rewards. First, our results establish present bias for losses—a psychological preference to have losses over with now. Present bias thus predicts increased discounting of future gains but decreased (or even negative) discounting of future losses. Second, because present bias preferences do not scale with the magnitude of possible gains or losses, they play a larger role, relative to other motivations for discounting, for small magnitude intertemporal decisions than for large magnitude intertemporal decisions. Present bias thus predicts less discounting of large gains than small gains but more discounting of large losses than small losses. The present research is the first to demonstrate that the effect of outcome magnitude on discount rates may be opposite for gains and losses and also the first to offer a theory (an extension of present bias) and process data to explain this interaction. The results suggest that policy efforts to encourage future‐oriented choices should frame outcomes as large gains or small losses. Copyright © 2012 John Wiley & Sons, Ltd.
Ligand Steric and Fluoroalkyl Substituent Effects on Enchainment Cooperativity and Stability in Bimetallic Nickel(II) Polymerization Catalysts
Authors: Weberski Michael P. , Chen Changle , Delferro Massimiliano , Marks Tobin J. 
Published: July 2012

AbstractThe synthesis and characterization of two neutrally charged bimetallic NiII ethylene polymerization catalysts, {2,7‐di‐[2,6‐(3,5‐di‐methylphenylimino)methyl]1,8‐naphthalenediolato}‐bis‐NiII(methyl)(trimethylphosphine) [(CH3)FI2‐Ni2] and {2,7‐di‐[2,6‐(3,5‐di‐trifluoromethyl‐phenylimino)methyl]‐1,8‐naphthalenediolato}‐bis‐NiII(methyl)(trimethyl‐phosphine) [(CF3)FI2‐Ni2)], are reported. The diffraction‐derived molecular structure of (CF3)FI2‐Ni2 reveals a Ni⋅⋅⋅Ni distance of 5.8024(5) Å. In the presence of ethylene and Ni(COD)2 or B(C6F5)3 co‐catalysts, these complexes along with their monometallic analogues [2‐tert‐butyl‐6‐((2,6‐(3,5‐dimethylphenyl)phenylimino)methyl)‐phenolate]‐NiII‐methyl(trimethylphosphine) [(CH3)FI‐Ni] and [2‐tert‐butyl‐6‐((2,6‐(3,5‐ditrifluoromethyl‐phenyl)phenylimino)methyl)phenolato]‐NiII‐methyl‐(trimethylphosphine) [(CF3)FI‐Ni], produce polyethylenes ranging from highly branched Mw=1400 oligomers (91 methyl branches per 1000 C) to low branch density Mw=92 000 polyethylenes (7 methyl branches per 1000 C). In the bimetallic catalysts, Ni⋅⋅⋅Ni cooperative effects are evidenced by increased product polyethylene branching in ethylene homopolymerizations (∼3× for (CF3)FI2‐Ni2 vs. monometallic (CF3)FI‐Ni), as well as by enhanced norbornene co‐monomer incorporation selectivity, with bimetallic (CH3)FI2‐Ni2 and (CF3)FI2‐Ni2 enchaining approximately three‐ and six‐times more norbornene, respectively, than monometallic (CH3)FI‐Ni and (CF3)FI‐Ni. Additionally, (CH3)FI2‐Ni2 and (CF3)FI2‐Ni2 exhibit significantly enhanced thermal stability versus the less sterically encumbered dinickel catalyst {2,7‐di‐[(2,6‐diisopropylphenyl)imino]‐1,8‐naphthalenediolato}‐bis‐NiII(methyl)(trimethylphosphine). The pathway for bimetallic catalyst thermal deactivation is shown to involve an unexpected polymerization‐active intermediate, {2,7‐di‐[2,6‐(3,5‐di‐trifluoromethyl‐phenylimino)methyl]‐1‐hydroxy,8‐naphthalenediolato‐NiII(methyl)‐(trimethylphosphine).
Gene expression profiling on pre‐ and post‐erlotinib tumors from patients with head and neck squamous cell carcinoma
Authors: Thomas Fabienne , Delmar Paul , Vergez Sébastien , Rochaix Philippe , Hennebelle Isabelle , McLoughlin Patricia , Benlyazid Adil , Sarini Jérôme , Delord Jean–Pierre 
Published: July 2012

AbstractBackgroundThe purpose of our work was to identify genomic predictive markers of erlotinib response in patients with head and neck squamous cell carcinoma (HNSCC).MethodsTumor tissue biopsies were collected before and after treatment for 39 patients. We analyzed genomic expression of the tumors using microarrays to (1) identify genes differentially expressed in baseline samples in patients who were responders vs nonresponders, (2) characterize erlotinib's effect on gene expression, and (3) identify the pharmacodynamic marker of erlotinib.ResultsGene expression profiles found no statistically significant differentially expressed genes between responders and nonresponders. An exploratory analysis by combining statistical criteria allowed us to identify genes differentially expressed in nonresponders compared to responders and genes whose expression was modified during erlotinib treatment. Finally, the search of pharmacodynamic markers identified cyclin‐dependent kinase 2‐interacting protein (CINP) as a potential marker of erlotinib efficacy because its expression decreased only in patients who were responders to the treatment.ConclusionThis study provides candidate genes potentially involved in erlotinib response in HNSCC. Head Neck, 2012
Tenascin‐C, GLUT‐1, and syndecan‐2 expression in juvenile nasopharyngeal angiofibroma: Correlations to vessel density and tumor stage
Authors: Renkonen Suvi , Heikkilä Päivi , Haglund Caj , Mäkitie Antti A. , Hagström Jaana 
Published: July 2012

AbstractBackgroundJuvenile nasopharyngeal angiofibroma (JNA) is a highly vascular tumor with some characteristics resembling those of vascular malformations. The significance of different growth and angiogenesis promoting factors for the etiology of JNA remains unsolved.MethodsWe analyzed the immunoexpressions of glucose transporter 1 (GLUT‐1), tenascin‐C (TNC), and syndecan‐2 in a series of 27 patients with JNA and compared these with each other and the clinical data to investigate their possible connections and role in the angiogenesis and growth of JNA.ResultsWe found that frequent stromal TNC expression had a strong correlation with vessel density and tumor stage and endothelial GLUT‐1 expression, when present, correlated with higher tumor stage. Stromal TNC and stromal GLUT‐1 expressions were also found to correlate with each other.ConclusionsThe immunoexpression of stromal TNC correlated with vascular density and higher tumors stage, which supports the idea of TNC having a role in the tumorigenesis of JNA putatively by promoting angiogenesis. © 2012 Wiley Periodicals, Inc. Head Neck, 2013
Maternal lead exposure during lactation persistently impairs testicular development and steroidogenesis in male offspring
Authors: Wang Hua , Ji Yan‐Li , Wang Qun , Zhao Xian‐Feng , Ning Huan , Liu Ping , Zhang Cheng , Yu Tao , Zhang Ying , Meng Xiu‐Hong , Xu De‐Xiang 
Published: July 2012

ABSTRACTLead (Pb) is a testicular toxicant. In the present study, we investigated the effects of maternal Pb exposure during lactation on testicular development and steroidogenesis in male offspring. Maternal mice were exposed to different concentration of lead acetate (200 or 2000 ppm) through drinking water from postnatal day (PND) 0 to PND21. As expected, a high concentration of Pb was measured in the kidneys and liver of pups whose mothers were exposed to Pb during lactation. In addition, maternal Pb exposure during lactation elevated, to a less extent, Pb content in testes of weaning pups. Testis weight in weaning pups was significantly decreased when maternal mice were exposed to Pb during lactation. The level of serum and testicular T was reduced in Pb‐exposed pups. The expression of P450scc, P45017α and 17β‐HSD, key enzymes for T synthesis, was down‐regulated in testes of weaning pups whose mothers were exposed to Pb during lactation. Interestingly, the level of serum and testicular T remained decreased in adult offspring whose mothers were exposed to Pb during lactation. Importantly, the number of spermatozoa was significantly reduced in Pb‐exposed male offspring. Taken together, these results suggest that Pb could be transported from dams to pups through milk. Maternal Pb exposure during lactation persistently disrupts testicular development and steroidogenesis in male offspring. Copyright © 2012 John Wiley & Sons, Ltd.
In vivoevaluation of novel amine‐terminated nanopore Ti surfaces
Authors: Yu Xiaolin , Ning Chengyun , Li Jingping , Huang Shanshan , Guo Yuanjun , Deng Feilong 
Published: July 2012

AbstractThe aim of this study was to evaluate the effects of the novel nanopore Ti surface and amine‐terminated Ti surface on peri‐implant bone formation and bone–implant bonding strength in a rabbit tibiae model. Characterization of the modified Ti surface, such as root‐mean square roughness, contact angle, and surface energy was evaluated using scanning electron microscopy, atomic force microscopy, and a Contact Angle Measurement System, respectively. The results from alkali treatment indicated that an interpenetrating dimensional porosity surface had been formed, whose morphology was similar to the amine‐terminated surface of self‐assembled monolayers after alkali treatment. The micro‐CT demonstrated that the amine‐terminated surface had higher bone volume ratio and higher mean trabecular thickness after 4 weeks of implantation. The push‐out test and histological examination showed no significant differences in the maximal force and bone–implant contact between the terminated surface and alkali‐treated surface. These novel dimensional nanoporous structures can significantly improve the initial stabilization and the osseointegration. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 100A:3428–3435, 2012.
Development of a hospitalist‐led‐and‐directed physical examination curriculum
Authors: Janjigian Michael P. , Charap Mitchell , Kalet Adina 
Published: July 2012

AbstractBACKGROUND: Deficiencies in physical examination skills among medical students, housestaff, and even faculty have been reported for decades, though specifics on how to address this deficit are lacking.METHODS: Our institution has made a commitment to improving key physical examination competencies across our general medicine faculty. Development of the Merrin Bedside Teaching Program was guided by a comprehensive needs assessment and based on a learner‐centered educational model. First, selected faculty fellows achieve expertise through mentorship with a master clinician. They then develop a bedside teaching curriculum in the selected domain and conclude by delivering the curriculum to peer faculty.RESULTS: We have developed curricula in examination of the heart, shoulder, knee, and skin. Currently, curricula are being developed in the examination of the lungs, critical care bedside rounds, and motivational interviewing. Curricula are integrated with educational activities of the internal medicine residency and medical school whenever possible.CONCLUSIONS: A hospitalist‐led physical examination curriculum is an innovative way to address deficits in physical exam skills at all levels of training, engenders enthusiasm for skills development from faculty and learners, offers scholarship opportunities to general medicine faculty, encourages collaboration within and between institutions, and augments the education of residents and medical students. Journal of Hospital Medicine 2012. © 2012 Society of Hospital Medicine.
The moderating effects of job control and selection, optimization, and compensation strategies on the age–work ability relationship
Authors: Weigl Matthias , Müller Andreas , Hornung Severin , Zacher Hannes , Angerer Peter 
Published: July 2012

SummaryWork ability describes employees' capability to carry out their work with respect to physical and psychological job demands. This study investigated direct and interactive effects of age, job control, and the use of successful aging strategies called selection, optimization, and compensation (SOC) in predicting work ability. We assessed SOC strategies and job control by using employee self‐reports, and we measured employees' work ability using supervisor ratings. Data collected from 173 health‐care employees showed that job control was positively associated with work ability. Additionally, we found a three‐way interaction effect of age, job control, and use of SOC strategies on work ability. Specifically, the negative relationship between age and work ability was weakest for employees with high job control and high use of SOC strategies. These results suggest that the use of successful aging strategies and enhanced control at work are conducive to maintaining the work ability of aging employees. We discuss theoretical and practical implications regarding the beneficial role of the use of SOC strategies utilized by older employees and enhanced contextual resources at work for aging employees. Copyright © 2012 John Wiley & Sons, Ltd.
Timing and level of nitrogen supply affect nitrogen distribution and recovery in two contrasting oat genotypes
Authors: Zhao Gui‐Qin , Ma Bao‐Luo , Ren Chang‐Zhong , Liang Bao‐Chang 
Published: July 2012

AbstractHuman diets containing oat (Avena sativa L.) grain offer health benefits resulting in an emerging interest in oat improvement. Information on nitrogen (N) uptake, distribution, and use efficiency (NUE) in oat is limited. A greenhouse study using a 15N‐labeling technique was conducted to determine the responses of two contrasting oat genotypes to timing and level of N deficiency. Hulled oat cv. Prescott and hulless cv. AC Gehl were grown in soil‐mix pot culture with five N treatments applied through modified Hoagland solutions. Differences in 15N accumulation, 15N distribution, plant N originating from the labeled source, and NUE between the contrasting cultivars, were examined for each N strategy. Level of N deficiency and timing of N supply of 15NH415NO3 greatly affected 15N distribution, the origins of plant N, and the amount of 15N recovered in the plant. When N was supplied from seedling emergence to maturity (T1), AC Gehl accumulated 61% more 15N in the shoots, but 46% less 15N in the grain than Prescott (0.43 vs. 0.80 mg plant–1), indicating that AC Gehl was less effective in producing grain yield than Prescott as AC Gehl produced greater total dry matter (DM). Withholding N supply until flag‐leaf stage (FL) increased 15N in the grain of both cultivars by 29.6%, resulting in the highest NUE. In most cases, there were larger portions of plant N derived from the labeled source for AC Gehl than for Prescott. Our results suggest that greater NUE in the newly released AC Gehl was associated with N accumulation in the vegetative tissues. It is concluded that genotype improvement of hulless oat should be focused on enhancing N‐translocation efficiency.
The influence of the final cause doctrine on anatomists of the sixteenth and seventeenth centuries concerning selected anatomical structures of the head and neck
Authors: Lydiatt Daniel D. , Bucher Gregory S. 
Published: July 2012

AbstractThe Doctrine of Final Cause, taken from Aristotle's “causes” and modified by Claudius (Aelius) Galen (of Pergamon) stated that for an anatomical part to exist it must have a “cause,” not an end point, but a purpose or goal, natural or divine. This affected the renaissance anatomist's thinking. We explore this doctrine's relationship with human head and neck anatomy from antiquity's Aristotle and Galen, and the leading renaissance anatomists from the 16th and 17th centuries. Their relevant writings were influenced by religious and political beliefs and varied from humanistic to reactionary.Tracing anatomical controversies through these works reveal the humanism of Vesalius and others as paralleling the humanists of art and literature. These controversies illustrate how the body was used to demonstrate function, uses, and causes from higher sources. Humanists advanced the social, philosophical, intellectual, literary, and medical/anatomical thoughts of this period. They stood between the Christian church of the Middle Ages and modern science.Like religion, medicine and anatomy had its own revealed sources of knowledge and had sacred texts like Galen's. Vesalius' the Fabrica and the woodcuts established suddenly the beginning of modern observational science and art as the direct and faithful representation of natural phenomena. They displayed anatomy such that others could understand, including errors of Galen, bringing Vesalius into ecclesiastical conflict. Evolutionary scientists today see mutations as favorable or unfavorable depending on the environment. Mutations are random or directed by divine plan, according to perspectives of this ancient debate. Laryngoscope, 2012
On extensions and restrictions of semigroups of linear operators in a Banach space and their applications
Authors: Gorbachuk M. , Gorbachuk V. 
Published: July 2012

AbstractThe description of all solutions on (0, ∞) of differential equations of parabolic and elliptic type in a Banach space is given without imposing any conditions on their behavior near the point 0, and the properties of them are studied. The necessary and sufficient conditions on the initial data, under which the Cauchy problem for a general operator‐differential equation is solvable in the class of locally analytic, entire or entire of finite order and finite type vector‐valued functions, are established. The results are based on the theory of restrictions and extensions of analytic semigroups set forth below.
On the syzygies and Alexander polynomials of nodal hypersurfaces
Authors: Dimca Alexandru , Sticlaru Gabriel 
Published: July 2012

AbstractWe give sharp lower bounds for the degree of the syzygies involving the partial derivatives of a homogeneous polynomial defining a nodal hypersurface. The result gives information on the position of the singularities of a nodal hypersurface expressed in terms of defects or superabundances.The case of Chebyshev hypersurfaces is considered as a test for this result and leads to a potentially infinite family of nodal hypersurfaces having nontrivial Alexander polynomials.
Toward online reconstruction of quantitative susceptibility maps: Superfast dipole inversion
Authors: Schweser Ferdinand , Deistung Andreas , Sommer Karsten , Reichenbach Jürgen Rainer 
Published: July 2012

AbstractMagnetic susceptibility is an intrinsic tissue property that recently became measureable in vivo by a magnetic‐resonance based technique called quantitative susceptibility mapping (QSM). Although QSM may be performed without additional acquisition time, for example, in the course of the well‐established susceptibility weighted imaging, the applicability of QSM is currently hampered by the numerical complexity and computational cost associated with the reconstruction procedure. This work introduces a novel QSM framework called superfast dipole inversion which allows rapid online reconstruction of susceptibility maps from wrapped raw gradient‐echo phase data. The algorithm relies on the extension and combination of several recent algorithms involving the precalculation of convolution kernels and the correction of inversion artifacts. Reconstruction of three‐dimensional high resolution susceptibility maps of the human brain was achieved with superfast dipole inversion in less than 20 s on a conventional workstation computer. Thus, superfast dipole inversion opens the door to an implementation of QSM on MR scanner hardware as well as to the routine reconstruction of large cohorts of datasets. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
Three‐dimensional integration strategies of singular functions introduced by the XFEM in the LEFM
Authors: Minnebo Hans 
Published: July 2012

SUMMARYThe use of the extended finite element method in the scope of linear elastic fracture mechanics induces the integration of singular functions in terms of the stiffness matrix and in the computation of stress intensity factors using the interaction integral method. An adapted method is proposed in this paper to treat efficiently the three‐dimensional case. The improvement is demonstrated by comparison with standard and other methods found in the literature. Copyright © 2012 John Wiley & Sons, Ltd.
The bipenalty method for arbitrary multipoint constraints
Authors: Hetherington Jack , Rodríguez‐Ferran Antonio , Askes Harm 
Published: July 2012

SUMMARYIn finite element (FE) analysis, traditional penalty methods impose constraints by adding virtual stiffness to the FE system. In dynamics, this can decrease the critical time step of the system when conditionally stable time integration schemes are used by introducing spurious modes with high eigenfrequencies. Recent studies have shown that using mass penalties alongside traditional stiffness penalties can mitigate this effect for systems with a one single‐point constraint. In the present work, we extend this finding to include systems with an arbitrary set of multipoint constraints. By analysing the generalised eigenvalue problem, we show that the values of spurious eigenfrequencies may be controlled by the choice of stiffness and mass penalty parameters. The method is demonstrated using numerical examples, including a one‐dimensional contact–impact formulation and a two‐dimensional crack propagation analysis. The results show that constraint imposition using the bipenalty method can be employed such that the critical time step of an analysis is unaffected, whereas also displaying superiority over the mass penalty method in terms of accuracy and versatility. Copyright © 2012 John Wiley & Sons, Ltd.