bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of coupling conditions in water way intersections
Authors: Herty Michael , Seaïd Mohammed
Published: July 2012

We present a numerical assessment of coupling conditions in T‐junction for water flow in open canals. The mathematical model is based on the well‐established shallow water equations for open channel flows. In the present work, the emphasis is given to the description of coupling conditions at canal‐to‐canal intersections. The accurate prediction of these coupling conditions is essential in order to achieve good performance and reliable numerical simulations of water canals in networks. There exist several theoretical results for coupling conditions in a reduced geometry. The purpose of our work is to numerically verify these conditions for different water flow regimes. More precisely, we consider a local zooming of the T‐junction resulting in a two‐dimensional flow problem at the canals intersection. A high‐order non‐oscillatory method is used for solving the governing two‐dimensional equations, and the water flow solutions are space‐averaged over the junction areas. The obtained are thereafter, used for verification and comparison with the theoretical results. Verifications are conducted for two types of junctions, namely the 1‐to‐2 and 2‐to‐1 situations. Copyright © 2012 John Wiley & Sons, Ltd.
Evolution of hippocampal shapes across the human lifespan
Authors: Yang Xianfeng , Goh Alvina , Chen Shen‐Hsing Annabel , Qiu Anqi
Published: July 2012

Aberrant hippocampal morphology plays an important role in the pathophysiology of aging. Volumetric analysis of the hippocampus has been performed in aging studies; however, the shape morphometry—which is potentially more informative in terms of related cognition—has yet to be examined. In this paper, we employed an advanced brain mapping technique, large deformation diffeomorphic metric mapping (LDDMM), and a dimensionality reduction approach, locally linear diffeomorphic metric embedding (LLDME), to explore age‐related changes in hippocampal shape as delineated from magnetic resonance (MR) images of 302 healthy adults aged from 18 to 94 years. Compared with the hippocampal volumes, the hippocampal shapes clearly showed the nonlinear trajectory of biological aging across the human lifespan, where the variation of hippocampal shapes by age was characterized by a cubic polynomial. By integrating of LDDMM and LLDME, we were also able to illustrate the average hippocampal shapes in each individual decade. In addition, LDDMM and LLDME facilitated the identification of 63 years as a threshold beyond which hippocampal morphological changes were accelerated. Adults over 63 years of age showed the inward‐deformation bilaterally in the head of the hippocampi and the left subiculum regardless of hippocampal volume reduction when compared to adults younger than 63. Hence, we demonstrated that the shape of anatomical structures added another dimension of structural morphological quantification beyond the volume in understanding aging. Hum Brain Mapp 34:3075–3085, 2013. © 2012 Wiley Periodicals, Inc.
Executive performance is related to regional gray matter volume in healthy older individuals
Authors: Ruscheweyh Ruth , Deppe Michael , Lohmann Hubertus , Wersching Heike , Korsukewitz Catharina , Duning Thomas , Bluhm Saskia , Stehling Christoph , Keller Simon S. , Knecht Stefan
Published: July 2012

Individual differences in executive functioning and brain morphology are considerable. In this study, we investigated their interrelation in a large sample of healthy older individuals. Digit span, trail‐making, and Stroop tasks were used to assess different executive subfunctions in 367 nondemented community‐dwelling individuals (50–81 years). Task performance was analyzed relative to brain structure using voxel‐based morphometry, corrected for age and sex. Improved task performance was associated with increased local gray matter volume in task‐specific patterns that showed partial, but not complete overlap with known task‐specific functional imaging patterns. While all three tasks showed associations with prefrontal gray matter volume as expected for executive functioning, the strongest overlap between the three tasks was found in insular cortex, suggesting that it has a previously underestimated role for executive functions. The association between the insular cortex and executive functioning was corroborated using stereological region‐of‐interest measurement of insular volume in a subgroup of 93 subjects. Quantitatively, the volume of the single most strongly related region explained 2.4 ± 1.1% of the variance in executive performance over and above the variance explained by age, which amounted to 7.4 ± 4.1%. The age‐independent peak associations between executive performance and gray matter described here occurred in regions that were also strongly affected by age‐related gray matter atrophy, consistent with the hypothesis that age‐related regional brain volume loss and age‐related cognitive changes are linked. Hum Brain Mapp 34:3333–3346, 2013. © 2012 Wiley Periodicals, Inc.
HOW WELL DO DIAGNOSIS‐RELATED GROUPS EXPLAIN VARIATIONS IN COSTS OR LENGTH OF STAY AMONG PATIENTS AND ACROSS HOSPITALS? METHODS FOR ANALYSING ROUTINE PATIENT DATA
Authors: Street Andrew , Kobel Conrad , Renaud Thomas , Thuilliez Josselin ,   ON BEHALF OF THE EURODRG GROUP
Published: July 2012

We set out an analytical strategy to examine variations in resource use, whether cost or length of stay, of patients hospitalised with different conditions. The methods are designed to evaluate (i) how well diagnosis‐related groups (DRGs) capture variation in resource use relative to other patient characteristics and (ii) what influence the hospital has on their resource use. In a first step, we examine the influence of variables that describe each individual patient, including the DRG to which the patients are assigned and a range of personal and treatment‐related characteristics. In a second step, we explore the influence that hospitals have on the average cost or length of stay of their patients, purged of the influence of the variables accounted for in the first stage. We provide a rationale for the variables used in both stages of the analysis and detail how each is defined. The analytical strategy allows us (i) to identify those factors that explain variation in resource use across patients, (ii) to assess the explanatory power of DRGs relative to other patient and treatment characteristics and (iii) to assess relative hospital performance in managing resources and the characteristics of hospitals that explain this performance. Copyright © 2012 John Wiley & Sons, Ltd.
Breast cancer survival in the US and Europe: A CONCORD high‐resolution study
Authors: Allemani Claudia , Sant Milena , Weir Hannah K. , Richardson Lisa C. , Baili Paolo , Storm Hans , Siesling Sabine , Torrella‐Ramos Ana , Voogd Adri C. , Aareleid Tiiu , Ardanaz Eva , Berrino Franco , Bielska‐Lasota Magdalena , Bolick Susan , Cirilli Claudia , Colonna Marc , Contiero Paolo , Cress Rosemary , Crocetti Emanuele , Fulton John P. , Grosclaude Pascale , Hakulinen Timo , Izarzugaza M. Isabel , Malmström Per , Peignaux Karin , Primic‐Žakelj Maja , Rachtan Jadwiga , Safaei Diba Chakameh , Sánchez Maria‐José , Schymura Maria J. , Shen Tiefu , Traina Adele , Tryggvadottir Laufey , Tumino Rosario , Velten Michel , Vercelli Marina , Wolf Holly J. , Woronoff Anne‐Sophie , Wu Xiaocheng , Coleman Michel P.
Published: July 2012

Breast cancer survival is reportedly higher in the US than in Europe. The first worldwide study (CONCORD) found wide international differences in age‐standardized survival. The aim of this study is to explain these survival differences. Population‐based data on stage at diagnosis, diagnostic procedures, treatment and follow‐up were collected for about 20,000 women diagnosed with breast cancer aged 15–99 years during 1996–98 in 7 US states and 12 European countries. Age‐standardized net survival and the excess hazard of death up to 5 years after diagnosis were estimated by jurisdiction (registry, country, European region), age and stage with flexible parametric models. Breast cancers were generally less advanced in the US than in Europe. Stage also varied less between US states than between European jurisdictions. Early, node‐negative tumors were more frequent in the US (39%) than in Europe (32%), while locally advanced tumors were twice as frequent in Europe (8%), and metastatic tumors of similar frequency (5–6%). Net survival in Northern, Western and Southern Europe (81–84%) was similar to that in the US (84%), but lower in Eastern Europe (69%). For the first 3 years after diagnosis the mean excess hazard was higher in Eastern Europe than elsewhere: the difference was most marked for women aged 70–99 years, and mainly confined to women with locally advanced or metastatic tumors. Differences in breast cancer survival between Europe and the US in the late 1990s were mainly explained by lower survival in Eastern Europe, where low healthcare expenditure may have constrained the quality of treatment.
A novel anti‐DR5 chimeric antibody and epirubicin synergistically suppress tumor growth
Authors: Qiu Yuhe , Zhang Zhixin , Shi Juan , Liu Shilian , Liu Yanxin , Zheng Dexian
Published: July 2012

Tumor necrosis factor‐related apoptosis‐inducing ligand (TRAIL) induces apoptosis in a variety of tumor cells. TRAIL receptor 2 (DR5) expression is high in tumor cells, transformed cells, and clinical tumor specimens and is low in most normal cells and tissues; therefore, DR5 is considered an attractive target for cancer therapy. In this study, HMCAZ5, a novel mouse–human chimeric antibody based on AD5‐10, was generated and stably expressed in CHO‐dhfr− cells. Highly purified HMCAZ5 exhibits a high affinity for the receptor that is equal to the parental mouse antibody, induces apoptosis in various cancer cells but not in normal hepatocytes, and elicits both antibody‐dependent cellular cytotoxicity and complement‐dependent cytotoxicity in various human cancer cells. The anthracycline anticancer drug epirubicin (EPB) synergizes the cytotoxicity of HMCAZ5 in cancer cells by upregulating DR5 expression on the cell surfaces, enhancing p53 expression, Bid cleavage, and JNK phosphorylation and downregulating c‐FLIP expression and Akt phosphorylation. Moreover, HMCAZ5 alone suppresses tumor growth, and EPB augments the tumoricidal activity in human colorectal and hepatocellular tumor xenografts in athymic nude mice. These data suggest that the anti‐DR5 chimeric antibody HMCAZ5 may have a clinical use and represents a useful immunological strategy, in combination with chemotherapy, for the treatment of cancer © 2012 IUBMB Life, 64(9): 757–765, 2012
Multiphoton imaging of the dentine‐enamel junction
Authors: Cloitre Thierry , Panayotov Ivan V. , Tassery Hervé , Gergely Csilla , Levallois Bernard , Cuisinier Frédéric J. G.
Published: July 2012

Multiphoton microscopy has been used to reveal structural details of dentine and enamel at the dentin‐enamel junction (DEJ) based on their 2‐photon excited fluorescence (2PEF) emission and second harmonic generation (SHG). In dentine tubule 2PEF intensity varies due to protein content variation. Intertubular dentin produces both SHG and 2PEF signals. Tubules are surrounded by a thin circular zone with a lower SHG signal than the bulk dentine and the presence of collagen fibers perpendicular to the tubule longitudinal axis is indicated by strong SHG responses. The DEJ appears as a low intensity line on the 2PEF images and this was never previously reported. The SHG signal is completely absent for enamel and aprismatic enamel shows a homogeneous low 2PEF signal contrary to prismatic enamel. The SHG intensity of mantle dentine is increasing from the dentine‐enamel junction in the first 12 μm indicating a progressive presence of fibrillar collagen and corresponding to the more external part of mantle dentine where matrix metallo‐proteases accumulate. The high information content of multiphoton images confirms the huge potential of this method to investigate tooth structures in physiological and pathological conditions. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Retracted: Physical properties, mechanical behavior, and electron microscopy study of a new α‐TCP block graft with silicon in an animal model
Authors: Maté‐Sánchez de Val José E. , Calvo‐Guirado Jose L. , Delgado‐Ruiz Rafael A. , Ramírez‐Fernández Mª P. , Negri Bruno , Abboud Marcus , Martínez Isabel M. , de Aza Piedad N.
Published: July 2012

This study reports the characterization process and in vivo application of a new block bone graft of α‐TCP with silicate in three different percentages in the aim of determining the influence of the silicate. Three groups of cylindrical implants (6 ± 0.01 mm diameter, 8 ± 0.01 mm length) with varying Si composition were studied: A: 3 wt % C2S; B: 1.5 wt % C2S; C: 100 wt % TCP–0 wt % C2S. These were implanted randomly in critical size defects in New Zealand rabbits. X‐ray diffraction analysis was performed to determine the crystalline phases of the different compositions. Histomorphometric analysis produced one measurement of bone‐to‐implant contact. Comparing the α‐TCPss ceramics, the trial found improved mechanical properties due to the silicon content in solid solution as well as densification. Previous studies have shown that the mechanical strengths of sintered ceramics correlate to densification as well as grain size and mechanical properties. Because of its mechanical and biological behavior, the study has shown α‐TCP with C2S to be an alternative to other bone graft substitutes for use in bone reconstructive surgery in the fields of veterinary, medicine, and oral and maxillofacial surgery. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 100A:3446–3454, 2012.
A new massively parallel version of CRYSTAL for large systems on high performance computing architectures
Authors: Orlando Roberto , Delle Piane Massimo , Bush Ian J. , Ugliengo Piero , Ferrabone Matteo , Dovesi Roberto
Published: July 2012

Fully ab initio treatment of complex solid systems needs computational software which is able to efficiently take advantage of the growing power of high performance computing (HPC) architectures. Recent improvements in CRYSTAL, a periodic ab initio code that uses a Gaussian basis set, allows treatment of very large unit cells for crystalline systems on HPC architectures with high parallel efficiency in terms of running time and memory requirements. The latter is a crucial point, due to the trend toward architectures relying on a very high number of cores with associated relatively low memory availability. An exhaustive performance analysis shows that density functional calculations, based on a hybrid functional, of low‐symmetry systems containing up to 100,000 atomic orbitals and 8000 atoms are feasible on the most advanced HPC architectures available to European researchers today, using thousands of processors. © 2012 Wiley Periodicals, Inc.
An Examination of the Diagnostic Efficiency of Post‐Deployment Mental Health Screens
Authors: Skopp Nancy A. , Swanson Robert , Luxton David D. , Reger Mark A. , Trofimovich Lily , First Michael , Maxwell James , Gahm Gregory A.
Published: July 2012

Objective

To conduct a blinded study to examine the diagnostic efficiency of the Department of Defense (DoD) Post‐Deployment Health Reassessment (PDHRA) screens for major depressive disorder (MDD), posttraumatic stress disorder (PTSD), and alcohol abuse.

Method

Participants were 148 post‐deployed soldiers who were completing the PDHRA protocol. Soldiers’ mean age was 27.7 (standard deviation = 6.6) years, and 89.0% were male. Mental health professionals blinded to the PDHRA screening results administered the Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition directly after the PDHRA assessment protocol.

Results

All screens exhibited excellent negative predictive power. Sensitivity metrics were lower, consistent with the relatively low base rates observed for MDD (10.1%), PTSD (8.8%), and alcohol abuse (5.4%). Metrics obtained for the PTSD screen were consistent with previous research with a similar base rate. A two‐item screen containing PTSD reexperiencing and hyperarousal symptom items revealed excellent psychometric properties (sensitivity = .92; specificity = .79). The alcohol abuse screen yielded high sensitivity (.86), but very poor precision; these metrics were somewhat improved when the screen was reduced to a single item.

Conclusions

The PDHRA MDD, PTSD, and alcohol abuse screens appear to be functioning well in accurately ruling out these diagnoses, consistent with a population‐level screening program. Cross validation of the current results is indicated. Additional refinement may yield more sensitive screening measures within constraints imposed by the low base rates in a typically healthy population.
Self‐Perceived Burden as a Mediator of Depression Symptoms Amongst Individuals Living With a Movement Disorder
Authors: Dempsey Laurie E. , Karver Marc S. , Labouliere Christa , Zesiewicz Theresa A. , De Nadai Alessandro S.
Published: July 2012

Objective

Movement disorders are chronic illnesses that can lead to functional impairment and psychological distress. This study examined the relations between functional impairment, depression, and anxiety in individuals with movement disorders, and whether these associations were mediated by feelings of self‐perceived burden.

Method

This cross‐sectional study sampled individuals (57 males and 57 females; mean age of 62) with chronic movement disorders from a movement disorders clinic. Patients completed measures of depression, anxiety, functional impairment, and self‐perceived burden.

Results

Functional impairment was associated with depression, but not anxiety, and was mediated by self‐perceived burden for individuals with chronic movement disorders.

Conclusions

Self‐perceived burden may have an important role relative to individuals’ adaptation to chronic illness with implications for future interventions.
The roles of water vapour, rainfall and solar radiation in determining air temperature change measured at Bet Dagan, Israel between 1964 and 2010
Authors: Stanhill Gerald , Rosa Rafael , Cohen Shabtai
Published: July 2012

Monthly mean values of climate at Bet Dagan in the central coastal plain of Israel, downwind of Tel Aviv, were analysed to yield seasonal and annual values of long‐ and short‐wave irradiance which were then related to changes in air temperature measured between 1964 and 2010. Over half the large interannual variation and significant increase in atmospheric long‐wave radiation, which averaged 0.7 W m−2 per decade, was associated with concurrent changes measured in specific humidity. The remaining changes were attributed to increases in concentrations of carbon dioxide and other anthropogenic radiatively active gases. Large decadal variations and a significant overall reduction in short‐wave solar radiation were measured averaging 3.6 W m−2 per decade which were, in part, attributed to urban pollution. Changes in downwelling long‐ and short‐wave irradiances together accounted for 58% of interannual variation in the mean annual temperature. Climate sensitivity to short‐wave radiation forcing was very low compared with that of long‐wave forcing resolving the paradox of the sharp rise in temperature accompanying negative all‐wave radiative forcing (RF). Possible physical mechanisms explaining the decoupling between annual values of solar irradiance and air temperature are discussed. A significant, inverse correlation between temperature and the annual number of rain days was found, accounting for 21% of the interannual variation in air temperature unexplained by surface RF. During the last 45 years, changes in annual temperature at Bet Dagan, a near‐coastal site with a strong urban influence situated in the semi‐arid Mediterranean climate, were associated, in the following order of importance, with changes in water vapour, rainfall and solar radiation. Copyright © 2012 Royal Meteorological Society
Identification of oxygen vacancy types from Raman spectra of SnO2 nanocrystals
Authors: Liu L. Z. , Li T. H. , Wu X. L. , Shen J. C. , Chu P. K.
Published: July 2012

Raman spectra acquired from spherical SnO2 nanocrystals prepared by pulsed laser ablation and hydrothermal synthesis exhibit three oxygen‐vacancy‐related Raman modes at 234, 573, and 618 cm−1. The peak location and intensity vary with annealing temperature under O2 finally approaching those of bulk materials. Density functional calculation discloses that the three Raman modes stem from subbridging, in‐plane, and bridging oxygen vacancies, respectively. Raman spectra can thus be used to discern different types of oxygen vacancies in SnO2 nanocrystals. Copyright © 2012 John Wiley & Sons, Ltd.
Incentives, Information, and Emergent Collective Accuracy
Authors: Hong Lu , Page Scott E. , Riolo Maria
Published: July 2012

In this paper, we construct a framework within which we explore how incentives and information structures influence the ability of a collection of individuals to make an accurate aggregate prediction. In our framework, individuals of bounded ability predict outcomes that depend on the values of a set of attributes. Individual construct models consider only a subset of those attributes, and those models depend on their incentives and their information environments. We consider two types of incentive structures: one in which individuals get paid on the basis of accuracy and one based on market like, for example, parimutuel payoffs. We also consider two information environments: one in which individuals learn in isolation and another in which they can copy more successful predictors. We find that market incentives and isolated learning environments produce the most accurate aggregate predictions but that these same incentives and information structures also produce the least accurate individuals. Thus, the incentives and informational structures that produce collective wisdom may hinge on their ability to produce and maintain diversity. Copyright © 2012 John Wiley & Sons, Ltd.
The kinetics of urinary fumonisin B1 excretion in humans consuming maize‐based diets
Authors: Riley Ronald T. , Torres Olga , Showker Jency L. , Zitomer Nicholas C. , Matute Jorge , Voss Kenneth A. , Gelineau‐van Waes Janee , Maddox Joyce R. , Gregory Simon G. , Ashley‐Koch Allison E.
Published: July 2012

Scope

Fumonisins (FB) are mycotoxins found in maize. The purpose of this study was to (i) determine the relationship between FB1, FB2, and FB3 intake and urinary excretion in humans, (ii) validate a method to isolate urinary FB on C18‐SPE cartridges for international shipment, and (iii) test the method using samples from Guatemala.

Methods and results

Volunteers (n = 10) consumed 206 grams/day of tortillas and biscuits prepared from masa flour and a product containing maize flour. Volunteers estimated their daily urine output and samples were analyzed for FB1, FB2, and FB3 and hydrolyzed FB1. Only FB1 was detected in urine suggesting lower absorption of FB2 and FB3. Excretion was highly variable peaking soon after consumption began and decreasing rapidly after consumption stopped. Within 5 days after consumption ended, FB1 was not detected in urine. In a study with eight volunteers, the average total urinary FB1 was 0.5% of the intake. FB1 was detected in 61% (107/177) of the samples collected in Guatemala.

Conclusion

The results support the use of urinary FB1 to assess ongoing exposure in popula‐tion‐based studies. However, relating the FB1 concentration in urine to dietary intake of FB by individual subjects will be complicated due to interindividual variability and the rapidity of clearance.
On building multiple spanning trees and VLAN assignment in metro ethernet networks
Authors: Meddeb Aref
Published: July 2012

While most of today's research effort is being devoted to wireless technologies involving the tiniest and most sophisticated devices, Ethernet is evolving from a best effort, plug‐and‐play LAN technology, towards a carrier‐grade WAN technology. Most of the new Ethernet standards rely on spanning tree protocols (STP) such as Rapid STP (RSTP) and multiple STP (MSTP). RSTP offers faster convergence than the legacy STP but like its predecessor, it uses a single tree to carry all the traffic offered to the network, seriously impacting throughput and bandwidth usage. MSTP however supports multiple spanning tree instances but does not provide generic methods to build those instances. Moreover, MSTP does not provide efficient methods to map between spanning trees and virtual LANs (VLAN). Operators must manually provision this mapping which seriously affects network operation expenditures and network performance. In this paper, we introduce a multiple spanning tree generation algorithm (MSTGA) and a VLAN‐spanning tree mapping algorithm (VSTMA) aimed at helping operators leverage their networks, save bandwidth, and support service level agreements with their customers. These algorithms can be used to extend and/or work with MSTP. We show that MSTGA maximizes throughput while VSTMA minimizes bandwidth usage. We also show that combining edge‐disjoint spanning trees with VSTMA constitutes the best bandwidth/throughput tradeoff. © 2012 Wiley Periodicals, Inc. NETWORKS, 2013
Preparation and properties of novel poly(propylene oxide)‐block‐polylactide‐based polyurethane foams
Authors: Ma Yan , Yang Dongmei , Shi Wenpeng , Li Suming , Fan Zhongyong , Tu Jianjun , Wang Wei
Published: July 2012

A novel degradable flexible polyurethane (PU) foam was prepared by varying the ratio of poly(propylene oxide) (PPO) and triarm poly(propylene oxide)‐block‐polylactide copolymer (PPO‐b‐PLA), and was compared with conventional PU foams based on toluene diisocyanate (TDI) and PPO. Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) showed that introducing PLA segments were able to result in a transition from a microphase separated state to a microphase mixed state and improve the microphase mixing. The changes in structure and domain size distribution associated with this transition were found to have led to enhanced mechanical properties such as the tensile strength, the elongation at break, and the rebound resilience for the PU foams containing PLA segments. Furthermore, it was observed that the network structure was destroyed by hydrolytic degradation in alkali solution (10 wt%/vol%) at 80°C for 50 h, and that as the PLA content increased, the degradation rate of PU foams enhanced. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
UCST and LCST phase behavior of poly(trimethylene ether) glycol in water
Authors: Lee Hau‐Nan , Rosen Brad M. , Fenyvesi Gyorgyi , Sunkara Hari B.
Published: July 2012

We describe the initial studies of the complex aqueous phase behavior of poly(trimethylene ether) glycol (PO3G), a renewably sourced polyether glycol. Cloud point measurement revealed that a low molecular weight PO3G exhibits both lower critical solution temperature (LCST) and upper critical solution temperature (UCST) in water in the temperature range between 30°C and 80°C. At low concentrations of PO3G, the polymer solutions exhibit LCST‐type phase behavior. In the intermediate concentration ranges, PO3G and water are immiscible. However, at higher concentrations of PO3G, the solutions show UCST‐type phase behavior. In addition, both the LCSTs and UCSTs can be easily tuned over a wide range by varying the amount of alcohol co‐solvents. These findings have potential applications in the design of personal care applications and in the development of thermosensitive “smart” materials. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Synthesis and optoelectronic properties of novel benzodifuran semiconducting polymers
Authors: Sista Prakash , Huang Peishen , Gunathilake Samodha S. , Bhatt Mahesh P. , Kularatne Ruvini S. , Stefan Mihaela C. , Biewer Michael C.
Published: July 2012

Two new semiconducting polymers poly{4,8‐bis(4‐decylphenylethynyl)benzo[1,2‐b:4,5‐b′]difuran} (P1) and poly {4,8‐bis(4‐decylphenylethynyl)benzo[1,2‐b:4,5‐b′]difuran‐alt‐4,8‐bis(4‐decylphenylethynyl)benzo[1,2‐b:4,5‐b′]dithiophene} (P2) have been synthesized. These polymers were tested in bulk heterojunction solar cells yielding power conversion efficiencies of 1.19% for P1 and 0.79% for P2. The surface morphology of the solar cell devices indicated that both the polymers display a granular morphology with smoother films displaying higher power conversion efficiencies. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
pH‐ and temperature‐sensitive statistical copolymers poly[2‐(dimethylamino)ethyl methacrylate‐stat‐2‐vinylpyridine] with Functional succinimidyl‐ester chain ends synthesized by nitroxide‐mediated polymerization
Authors: Zhang Chi , Maric Milan
Published: July 2012

Statistical copolymerizations of 2‐(dimethylamino)ethyl methacrylate (DMAEMA) with 2‐vinylpyridine (2VP) with 80 to 99 mol % DMAEMA in the feed utilizing a succinimidyl ester‐terminated alkoxyamine unimolecular initiator (NHS‐BlocBuilder) at 80 °C in bulk were performed. The effectiveness of 2VP as a controlling comonomer is demonstrated by linear increases in number‐average molecular weight versus conversion, relatively low PDI (1.5–1.6 with up to 98% DMAEMA) and successful chain extensions with 2VP. Additional free nitroxide does not significantly improve control for the DMAEMA/2VP copolymerizations. The succinimidyl ester on the initiator permits coupling to amine‐terminated poly(propylene glycol) (PPG), yielding an effective macroinitiator for synthesizing a doubly thermo‐responsive block copolymer of PPG‐block‐P(DMAEMA/2VP). A detailed study of the thermo‐ and pH‐sensitivities of the statistical and block copolymers is also presented. The cloud point temperature of the statistical copolymers is fine tuned from 14 to 75 °C by varying polymer composition and pH. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012.
Mitigation of Single‐Point‐of‐Failure: Development of M127A1 White Star Illuminant Compositions Containing an Epoxy Binder System
Authors: Sabatini Jesse J. , Raab James M. , Hann Ronald K.
Published: July 2012

A replacement for the M127A1 hand‐held signal illuminant was developed to alleviate concerns associated with single‐point‐of‐failure. In addressing single‐point‐of‐failure, Laminac 4116/Lupersol binder system were replaced with Epon 813/Versamid 140 binder system. Powdered sodium nitrate was replaced with prilled sodium nitrate in the disclosed formulations to minimize hygroscopicity concerns associated with this oxidizer. The performance of the prilled sodium nitrate‐based formulations, their burning behaviors, and the sensitivities of the best performing illuminant toward various ignition stimuli are also described in detail.
Charge‐transport physics of high‐mobility molecular semiconductors
Authors: Sirringhaus Henning , Sakanoue Tomo , Chang Jui‐Fen
Published: July 2012

This review is focused on understanding of the charge‐transport physics of high‐mobility organic semiconductors at a molecular level. We review recent high‐mobility small‐molecule and conjugated polymer materials with a focus on crystalline materials that have been able to exceed mobilities of 0.5–1 cm2/V s. We discuss some of the main, competing factors that govern charge transport in these materials and present theoretical approaches that have been developed to describe systems in which moderately strong intermolecular electronic interactions and strong electron–phonon interactions are present. Finally, we review recent experimental results that have aimed to address the important question of whether at room‐temperature charge carriers in these high‐mobility organic semiconductors are in fact simply extended Bloch electrons that undergo occasional scattering processes or are localized on individual molecules and move by hopping.
Circuit model for hybridization modes in metamaterials and its analogy to the quantum tight‐binding model
Authors: Nakata Yosuke , Okada Takanori , Nakanishi Toshihiro , Kitano Masao
Published: July 2012

We formulate a general method to analyze hybridization modes in metamaterials by employing electrical circuit models. By rewriting circuit equations for coupled inductor–capacitor circuit networks in the bra‐ket notation, we show that there exists a good analogy between circuit models and quantum tight‐binding models in solid‐state physics. Our picture is also applicable to transmission systems that do not have tightly bound eigenmodes.

This analogy enables the synthesis of various electromagnetic metamaterials having dispersion relations similar to those for electrons in solids and consequently allows the systematic construction of metamaterials with desired characteristics. In this paper, we focus on the formation of flat bands in metamaterials with specific symmetries. The flat band, which corresponds to a slow group velocity of light or a heavy photon, is useful in designing functional metamaterials.
Density functional study of the TiN/Ge2Sb2Te5 interface
Authors: Mandelli D. , Caravati S. , Bernasconi M.
Published: July 2012

We studied the epitaxial TiN(001)/Ge2Sb2Te5(001) (GST) interface of interest for applications in phase change non‐volatile memories by means of density functional calculations. The cubic phase of GST of interest for the memory devices was considered. From geometry optimization we found an equilibrium distance of about 3.0 Å between Ti and Te, Ge and Sb atoms located directly above along the [001] direction. The interface formation energy of a large 1440‐atom model is γint = 50 meV/Å2. The surface energy of TiN(001) and GST(001) are γS = 81 and 10 meV/Å2 resulting in an adhesion energy of γad = 41 meV/Å2. A good adhesion between the two materials can thus be achieved in the ideal epitaxial configuration. The presence of metal induced gap states (MIGS) is revealed by the analysis of Kohn–Sham (KS) orbitals.
A glass thinning and texturing method for light incoupling in thin‐film polycrystalline silicon solar cells application
Authors: Cui Hongtao , Campbell Patrick R.
Published: July 2012

For polycrystalline silicon (poly‐Si) thin‐film solar cells on ∼3 mm borosilicate glass, glass thinning reduces the glass absorption and light leaking to neighbouring cells; the glass texturing of the sun‐facing side suppresses reflection. In this Letter, a labour‐free wet etching method is developed to texture and thin the glass at the same time in contrast to conventionally separated labour‐intensive glass thinning and texturing processes. For 2 cm2 size poly‐Si thin‐film solar cells on glass superstrate, this wet etching successfully thins down the glass from 3 mm to 0.5 mm to check the ultimate benefit of the process and introduces a large micron texture on the sun‐facing glass surface. The process enhances Jsc by 6.3% on average, with the optimal Jsc enhancement of 8%, better than the value of 4.6% found in the literature. This process also reduces the loss in external quantum efficiency (EQE loss), which is due to light leaking to neighbouring cells, dramatically. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mangifera indica L. Extract and Mangiferin Modulate Cytochrome P450 and UDP‐Glucuronosyltransferase Enzymes in Primary Cultures of Human Hepatocytes
Authors: Rodeiro Idania , José Gómez‐Lechón M. , Perez Gabriela , Hernandez Ivones , Herrera José Alfredo , Delgado Rene , Castell José V. , Teresa Donato M.
Published: July 2012

The aqueous stem bark extract of Mangifera indica L. (MSBE) has been reported to have antioxidant, anti‐inflammatory and analgesic properties. In previous studies, we showed that MSBE and mangiferin, its main component, lower the activity of some cytochrome P‐450 (P450) enzymes in rat hepatocytes and human liver microsomes. In the present study, the effects of MSBE and mangiferin on several P450 enzymes and UDP‐glucuronosyltransferases (UGTs) in human‐cultured hepatocytes have been examined. After hepatocytes underwent a 48‐h treatment with sub‐cytotoxic concentrations of the products (50–250 µg/mL), a concentration‐dependent decrease of the activity of the five P450 enzymes measured (CYP1A2, 2A6, 2C9, 2D6 and 3A4) was observed. For all the activities, a reduction of at least 50% at the highest concentration (250 µg/mL) was observed. In addition, UGT activities diminished. MSBE considerably reduced UGT1A9 activity (about 60% at 250 µg/mL) and lesser effects on the other UGTs. In contrast, 250 µg/mL mangiferin had greater effects on UGT1A1 and 2B7 than on UGT1A9 (about 55% vs. 35% reduction, respectively). Quantification of specific mRNAs revealed reduced CYP3A4 and 3A5 mRNAs content, and an increase in CYP1A1, CYP1A2, UGT1A1 and UGT1A9 mRNAs. No remarkable effects on the CYP2A6, 2B6, 2C9, 2C19, 2D6 and 2E1 levels were observed. Our results suggest that the activity and/or expression of major P450 and UGT enzymes is modulated by MSBE and that potential herb–drugs interactions could arise after a combined intake of this extract with conventional medicines. Therefore, the potential safety risks of this natural product derived by altering the ADMET properties of co‐administered drugs should be examined. Copyright © 2012 John Wiley & Sons, Ltd.
Protective Effects of a Purified Saponin Mixture from Astragalus corniculatus Bieb., in vivo Hepatotoxicity Models
Authors: Vitcheva Vessela , Simeonova Rumyana , Krasteva Ilina , Nikolov Stefan , Mitcheva Mitka
Published: July 2012

In this study, the in vivo effects of a purified saponin mixture (PSM), obtained from Astragalus corniculatus Bieb., were investigated using two in vivo hepatotoxicity models based on liver damage caused by paracetamol (PC) and carbon tetrachloride (CCl4). The effects of PSM were compared with silymarin. Male Wistar rats were challenged orally with 20% CCl4 or PC (2 g/kg) four days after being pre‐treated with PSM (100 mg/kg) or silymarin (200 mg/kg). A significant decrease of aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase (LDH) activities and glutathione (GSH) levels and an increase of malondialdehyde (MDA) quantity was observed after CCl4 and PC administration alone. PSM pre‐treatment decreased serum transaminases and LDH activities and MDA levels and increased the levels of cell protector GSH. Biotransformation phase I enzymes were also assessed in both models. In the CCl4 hepatotoxicity model, pre‐treatment with PSM or silymarin resulted in significantly increased activities of ethylmorphine‐N‐demethylase and aniline 4‐hydroxylase activity and cytochrome P450, compared to the CCl4 only group. Neither silymarin nor PSM influenced PC biotransformation. Our results suggest that PSM, obtained from A. corniculatus, Bieb. showed in vivo hepatoprotective and antioxidant activities against CCl4 and PC‐induced liver damage comparable to that of silymarin. Copyright © 2012 John Wiley & Sons, Ltd.
On the representation matrices for the symmetric group adapted to electron‐pair and electron‐group wave functions using graphical methods of spin algebras
Authors: Wilson S. , Hubač I.
Published: July 2012

Using graphical methods of spin algebras, we present a direct method for the determination of the representation matrices of the symmetric group in a basis adapted to electron‐pair and electron‐group wave functions. In particular, we consider nonstandard representations adapted to
$S_{n_1 } \times S_{n_2 } \times \ldots \times S_{n_\ell }$
where n1 + n2 + … + nℓ = n. The Serber coupling scheme based on S2 × S2 × …× S2 is a special case suited for electron‐pair wave functions. Our approach exploiting graphical methods of spin algebras is contrasted with the use of Young diagrams and tableaux, Yamanouchi symbols and branching diagrams. © 2012 Wiley Periodicals, Inc.
Generalized oscillator strength of endohedral molecules
Authors: Amusia M. Ya. , Chernysheva L. V. , Liverts E. Z.
Published: July 2012

We calculate here the main characteristic of the fast electron scattering on endohedrals, namely their generalized oscillator strength (GOS), total and differential in the angle of atomic electron emission. Endohedrals are atoms A staffed inside the fullerene CN and denoted as A@CN. We take into account two major effects of CN on ionization of the atom A: the scattering of the emitted electron by the static potential of the fullerenes shell and the modification of the interaction between the fast incoming and atomic electrons due to polarization of the fullerenes shell by the incoming electron beam. We substitute the complex fullerenes shell CNby a static zero thickness potential, and express its deformation under incoming electron action via CNpolarizabilities. We perform all consideration in the frame of the random phase approximation with exchange that gave reliable results for GOSes of isolated atoms. We limit ourselves with the dipole and the biggest nondipole contributions to the differential in angle GOSes. We compare differential in angle GOSes with differential in angle photoionization cross‐section as a source of information on the target electronic structure and emphasize some advantages of the fast electron scattering. The concrete objects of calculations are noble gas endohedrals Ar@C60 and Xe@C60, and the results are presented for two transferred momentum q values, q = 0.1 and 1.0. Even for small q = 0.1, in the optical limit, the deviation from photoionization case is prominent and instructive. We demonstrate impressive new features of GOSes that appear due to fullerenes shell actions—regular oscillations and very big maxima. As an interesting and very specific object, we study onion‐type endohedrals A@CN1@CN2, in which the construction A@CN1 is stuffed inside CN2 with N2 >> N1. The consideration is similar to that developed in our recent article on total and differential in angle GOSes of isolated atoms (Amusia et al., Phys. Rev. 2012, A 85, 042722). © 2012 Wiley Periodicals, Inc.
Continuous flow reaction monitoring using an on‐line miniature mass spectrometer
Authors: Browne Duncan L. , Wright Steven , Deadman Benjamin J. , Dunnage Samantha , Baxendale Ian R. , Turner Richard M. , Ley Steven V.
Published: July 2012

RATIONALE

A recently developed miniature electrospray ionisation mass spectrometer has been coupled to a preparative flow chemistry system in order to monitor reactive intermediates and competing reaction paths, screen starting materials, and optimise reaction conditions. Although ideally suited to the application, mass spectrometers have rarely been used in this way, as traditional instruments are too bulky to be conveniently coupled to flow chemistry platforms.

METHODS

A six‐port switching valve fitted with a 5 μL loop was used to periodically sample the flow stream leaving the reactor coil. Mass spectra corresponding to the sample loop contents were observed approximately 10 s after activating the valve. High fluidic pressure was maintained throughout to ensure that gaseous products remained in solution. As an illustrative example of how this apparatus can be employed, the generation of benzyne and its subsequent reaction with furan were investigated. Benzyne was prepared via diazotisation of anthranilic acid using tert‐butyl nitrite.

RESULTS

Unexpectedly, the explosive diazotised intermediate was detected by the mass spectrometer at low coil temperatures or short residence times. The optimum reactor temperature and residence time for production of the desired Diels‐Alder product are 50 °C and 3–5 min, respectively. There are competing reaction pathways leading to the formation of acridone and several other by‐products.

CONCLUSIONS

On‐line mass spectrometry allowed the flow conditions to be quickly tuned for safe operation and optimal generation of the desired product. The validity of this approach was corroborated by off‐line liquid chromatography/mass spectrometry (LC/MS) analysis of flow samples. Copyright © 2012 John Wiley & Sons, Ltd.
MORPHOLOGICALLY RELATED INTEGRATIVE MANAGEMENT CONCEPT FOR RECONNECTING ABANDONED CHANNELS BASED ON AIRBORNE LiDAR DATA AND HABITAT MODELLING
Authors: Hauer Christoph , Mandlburger Gottfried , Schober Bernhard , Habersack Helmut
Published: July 2012

Most of the large rivers are heavily degraded and lack near‐natural conditions due to high human pressure (agricultural use and settlements) especially on former inundation areas. Hence, it is rarely possible to ‘restore’ predisturbance conditions of rivers and their floodplains. Further, river or floodplain restoration programs are often based on type‐specific reference conditions. Those reference conditions are mainly determined on the basis of historical maps not giving any information of, for example, sediment supply, flood frequency and vegetation cover (density). Especially for improving the ecological status of rivers with abandoned channel features, key habitats for target fish species have to be restored by reconnecting floodplains and their secondary channel system. In addition, because of the necessity of improving the ecological status, there is growing interest in interdisciplinary river restoration techniques. Within the presented article, an integrative concept is derived based on Light Detection and Ranging measurements and numerical modelling with respect to river dynamics (hydrologic and morphological). Further habitat modelling, based on unsteady depth‐averaged two‐dimensional hydrodynamics, is applied with a focus on the mesounit scale. For testing the conceptual model, various river reaches at the Morava River were selected, featuring different morphological characteristics. It was found that the applied management concept allows considering the important issues of river dynamics (morphological/hydrologic) using a flow‐ and flood‐pulse approach for identifying bottlenecks of target species at the Morava River. The reconnection of abandoned channels will result in an increase of hydromorphological heterogeneity and/or woody debris within the study reach. This might be of high relevance for habitat features (e.g. backwater habitats) especially for flow pulses between low flow and mean flow and/or in reaches without abandoned channels between low‐flow and the bankfull stage. Copyright © 2012 John Wiley & Sons, Ltd.
Robust parameter design for system dynamics models: a formal approach based on goal‐seeking behavior
Authors: Ng Tsan Sheng , Sy Charlle Lee , Lee Loo Hay
Published: July 2012

Parametric uncertainties in system dynamics models can cause undesirable behavior, and if unaccounted for in the design phase can impair the ability of the system to meet design requirements. Sensitivity analysis, while useful in the modeling process, does not by itself offer a systematic method to the problem of system design under uncertainties. In this work, we propose an optimization model‐based approach with the aim of obtaining a parametric design for system dynamics models that is robust against uncertainties. Our research synthesizes recent developments in robust optimization technology, eigenvalue analysis and the goal‐seeking behavior of decision agents. To this end, we develop a mathematical model that is computationally efficient to solve and effective in hedging against parametric uncertainties. Numerical case studies conducted using a hare and lynx model and an inventory–workforce model demonstrate significant improvements of the proposed designs in achieving system requirements under uncertainty. Copyright © 2012 System Dynamics Society.
Measurement of energy spectra on irradiated polycrystalline UO2 samples using secondary ion mass spectrometry
Authors: Roure I. , Pasquet B. , Desgranges L. , Bienvenu Ph.
Published: July 2012

The energy spectrum of uranium in irradiated fuels is known to give key information on the oxidation state of uranium at the sample surface. In this respect, it is essential to know the operating conditions applied to measure energy spectra by secondary ion mass spectrometry in order to obtain reliable data. Using a focussed beam on CAMECA IMS6f, the acquisition of an energy spectrum is performed along a line on the sample surface because the primary beam position moves as a function of the high voltage. Depending on the size of UO2 grains, the analysed area can be limited within one single grain or spread among many grains. The consequences of such acquisition conditions are discussed in this paper. Copyright © 2012 John Wiley & Sons, Ltd.