bluuebunny/crossref_metadata_2025 huggingface dataset:
The perforator angiosome: A new concept in the design of deep inferior epigastric artery perforator flaps for breast reconstruction
Authors: Rozen Warren M. , Ashton Mark W. , Le Roux Cara Michelle , Pan Wei‐Ren , Corlett Russell J.
Published: July 2009

Background: The previously described “perfusion zones” of the abdominal wall vasculature are based on filling of the deep inferior epigastric artery (DIEA) and all its branches simultaneously. With the advent of the DIEA perforator flap, only a single or several perforators are included in supply to the flap. As such, a new model for abdominal wall perfusion has become necessary. The concept of a “perforator angiosome” is thus explored. Methods: A clinical and cadaveric study of 155 abdominal walls was undertaken. This comprised the use of 10 whole, unembalmed cadaveric abdominal walls for angiographic studies, and 145 abdominal wall computed tomographic angiograms (CTAs) in patients undergoing preoperative imaging of the abdominal wall vasculature. The evaluation of the subcutaneous branching pattern and zone of perfusion of individual DIEA perforators was explored, particularly exploring differences between medial and lateral row perforators. Results: Fundamental differences exist between medial row and lateral row perforators, with medial row perforators larger (1.3 mm vs. 1 mm) and more likely to ramify in the subcutaneous fat toward the contralateral hemiabdomen (98% of cases vs. 2% of cases). A model for the perfusion of the abdominal wall based on a single perforator is presented. Conclusion: The “perforator angiosome” is dependent on perforator location, and can mapped individually with the use of preoperative imaging. © 2009 Wiley‐Liss, Inc. Microsurgery, 2010.
A quasi optimal Petrov–Galerkin method for Helmholtz problem
Authors: Loula Abimael F. D. , Fernandes Daniel T.
Published: July 2009

A Petrov–Galerkin finite element formulation is introduced for Helmholtz problem in two dimensions using polynomial weighting functions. At each node of the mesh, a global basis function for the weighting space is obtained adding to the bilinear C0 Lagrangian weighting function linear combinations of polynomial bubbles defined on a macroelement containing this node. Quasi optimal weighting functions, with the same support of the corresponding global test functions, are obtained after computing the coefficients of these linear combinations attending to optimality criteria. This is done numerically through a simple preprocessing technique naturally applied to non‐uniform and unstructured meshes. In particular, for uniform mesh a quasi optimal interior stencil of the same order of the quasi‐stabilized finite element method stencil derived by Babuška et al. (Comput. Methods Appl. Mech. Engrg 1995; 128:325–359) is obtained. Numerical results are presented illustrating the great stability and accuracy of this formulation with uniform and non‐uniform meshes. Copyright © 2009 John Wiley & Sons, Ltd.
A method for interpolating on manifolds structural dynamics reduced‐order models
Authors: Amsallem David , Cortial Julien , Carlberg Kevin , Farhat Charbel
Published: July 2009

A rigorous method for interpolating a set of parameterized linear structural dynamics reduced‐order models (ROMs) is presented. By design, this method does not operate on the underlying set of parameterized full‐order models. Hence, it is amenable to an online real‐time implementation. It is based on mapping appropriately the ROM data onto a tangent space to the manifold of symmetric positive‐definite matrices, interpolating the mapped data in this space and mapping back the result to the aforementioned manifold. Algorithms for computing the forward and backward mappings are offered for the case where the ROMs are derived from a general Galerkin projection method and the case where they are constructed from modal reduction. The proposed interpolation method is illustrated with applications ranging from the fast dynamic characterization of a parameterized structural model to the fast evaluation of its response to a given input. In all cases, good accuracy is demonstrated at real‐time processing speeds. Copyright © 2009 John Wiley & Sons, Ltd.
A switching control strategy for the attenuation of blood glucose disturbances
Authors: Markakis Mihalis G. , Mitsis Georgios D. , Papavassilopoulos George P. , Ioannou Petros A. , Marmarelis Vasilis Z.
Published: July 2009

In this computational study we consider a generalized minimal model structure for the intravenously infused insulin–blood glucose dynamics, which can represent a wide variety of diabetic patients, and augment this model structure with a glucose rate disturbance signal that captures the aggregate effects of various internal and external factors on blood glucose. Then we develop a model‐based, switching controller, which attempts to balance between optimal performance, reduced computational complexity and avoidance of dangerous hypoglycaemic events. We evaluate the proposed algorithm relative to the widely studied proportional—derivative controller for the regulation of blood glucose with continuous insulin infusions. The results show that the proposed switching control strategy can regulate blood glucose much better than the proportional—derivative controller for all the different types of diabetic patients examined. This new algorithm is also shown to be remarkably robust in the event of concurrent, unknown variations in critical parameters of the adopted model. Copyright © 2009 John Wiley & Sons, Ltd.
Metallocene based polyolefin: a potential candidate for the replacement of flexible poly (vinyl chloride) in the medical field
Authors: Sunny M. C. , Ramesh P. , Mohanan P. V. , George K. E.
Published: July 2009

A comparative assessment of the performance properties of metallocene polyolefin (m‐PO) with those of plasticized poly (vinyl chloride) (pPVC) and ethylene vinyl acetate (EVA) copolymer having 18% vinyl acetate content (EVA‐18), the two common polymers used for flexible medical products, is carried out. The preliminary evaluation of the processability, mechanical properties, and thermal stability of the new material, m‐PO is described. The processability parameters like mixing torque and melt viscosity of m‐PO are found to be comparable with those of pPVC and EVA‐18. Mechanical properties such as tensile strength, elongation at break, and tear strength (TS) of m‐PO are much higher than that of pPVC and EVA‐18. Thermo gravimetric analysis (TGA) indicates that the thermal degradation of m‐PO takes place only at temperatures above 340°C and can be processed at 170°C without much damage. Oxygen and carbon dioxide permeabilities of m‐PO at three different temperatures (10, 25, and 40°C) are evaluated and compared with those of pPVC and EVA‐18. It could be seen that the permeabilities of both the gases for m‐PO at three temperatures were lower than those of pPVC and EVA. Biological evaluation of m‐PO is carried out by assessing its cytotoxicity, hemolytic property, and blood clotting initiation. The cytotoxicity studies indicate that m‐PO is non‐toxic to the monolayer of L929 mammalian fibroblast cell lines on direct contact or the exposure of its extract. Non‐hemolytic property of m‐PO by direct contact as well as test on extract is revealed both in static and in dynamic conditions. Blood clotting time experiments indicate that the initiation of blood clotting due to m‐PO is faster than that of pPVC and EVA‐18. Copyright © 2009 John Wiley & Sons, Ltd.
A study of the behavior of charge carriers in an organic non‐volatile memory device with a thin metal layer between polymers
Authors: Choi Jin‐Sik , Cho Young Suk , Yook Ju Young , Suh Dong Hack
Published: July 2009

The behaviors of charge carriers were investigated to understand the reversible bistability in the polymer device with an embedded thin metal layer between the metal electrodes. The reversible bistability was sensitive to the condition of the embedded thin metal layer that was prepared by depositing 5 nm Al by 0.8 Å/sec. The device was controlled by the charge and the discharge in the effective trap sites of the embedded Al layer. Poly(N‐vinylcarbazole) as an organic active material merely conducted the charge transport function. The effective trap sites were contributed by the change of the reversible conductance and also preferred to be in a high conduction state. They took relatively low energy states easily as the device was affected by thermal stimulation at 150°C. The modification of the embedded Al layer improved its performances. Copyright © 2009 John Wiley & Sons, Ltd.
Parental expectations, experiences and reactions, sense of coherence and grade of anxiety related to routine ultrasound examination with normal findings during pregnancy
Authors: Ekelin M. , Crang Svalenius E. , Larsson A‐K. , Nyberg P. , Maršál K. , Dykes A‐K.
Published: July 2009

Objective

To investigate parents' expectations, experiences and reactions, sense of coherence and anxiety before and after a second‐trimester routine ultrasound examination, with normal findings.

Methods

Before and after ultrasound questionnaires including the scales parents' expectations, experiences and reactions to routine ultrasound examination (PEER‐U state of mind index), sense of coherence (SOC) and state and trait anxiety inventory (STAI), were sent to a 1‐year cohort of women and their partners. Replies received were 2183.

Results

Both parents had significantly less worried state of mind (PEER‐U) after the examination than before. Women had a lower grade of state anxiety after than before, but for men there was no significant change. Before the ultrasound, women had a higher degree of worried state of mind, as well as a higher grade of state and trait anxiety and a lower sense of coherence, than men. The women showed a greater reduction in worried state of mind than the men after the ultrasound examination. There were no significant differences in sense of coherence before and after ultrasound.

Conclusions

Women and men are affected in their psychological well‐being in relation to a routine ultrasound examination, but their sense of coherence remains stable. Copyright © 2009 John Wiley & Sons, Ltd.
Decreased serum levels of kisspeptin in early pregnancy are associated with intra‐uterine growth restriction and pre‐eclampsia
Authors: Armstrong R. Anne , Reynolds Rebecca M. , Leask Rosemary , Shearing Catherine H. , Calder Andrew A. , Riley Simon C.
Published: July 2009

Objective

To investigate whether pregnancies with development of subsequent pre‐eclampsia and intra‐uterine growth restriction are associated with altered levels of kisspeptin in maternal serum in the second trimester.

Study Design

Retrospective case–control study of 16–20 week serum samples matched for duration of storage at −70 °C. Levels of kisspeptin were measured in serum from women with pregnancies with subsequent development of pre‐eclampsia (n = 57), intra‐uterine growth restriction (n = 118), and matched controls (n = 317).

Results

Serum kisspeptin levels were significantly lower in those women who subsequently developed pre‐eclampsia than in controls [median (quartile range) 1109 (449) vs 1188 (365) pg/mL, p = 0.029] and in those with intra‐uterine growth restriction [1164 (386) vs 1188 (365) pg/mL, p = 0.016].

Conclusions

Kisspeptin levels are lower in maternal serum in the second trimester, in pregnancies associated with placental dysfunction. The differences in kisspeptin are modest, so although not forming a single screening marker in pre‐eclampsia and intra‐uterine growth restriction, measurement of kisspeptin may be useful in combination with other markers. Understanding the role of kisspeptin in the establishment of the placenta may further our knowledge of the mechanisms underlying placental function. Copyright © 2009 John Wiley & Sons, Ltd.
Synthesis of amphiphilic and thermoresponsive ABC miktoarm star terpolymer via a combination of consecutive click reactions and atom transfer radical polymerization
Authors: Li Changhua , Ge Zhishen , Liu Hewen , Liu Shiyong
Published: July 2009

Well‐defined amphiphilic and thermoresponsive ABC miktoarm star terpolymer consisting of poly(ethylene glycol), poly(tert‐butyl methacrylate), and poly(N‐isopropylacrylamide) arms, PEG(‐b‐PtBMA)‐b‐PNIPAM, was synthesized via a combination of consecutive click reactions and atom transfer radical polymerization (ATRP). Click reaction of monoalkynyl‐terminated PEG with a trifunctional core molecule bis(2‐azidoethyl)amine, (N3)2NH, afforded difunctional PEG possessing an azido and a secondary amine moiety at the chain end, PEG‐NHN3. Next, the amidation of PEG‐NHN3 with 2‐chloropropionyl chloride led to PEG‐based ATRP macroinitiator, PEG(N3)Cl. The subsequent ATRP of N‐isopropylacrylamide (NIPAM) using PEG(N3)Cl as the macroinitiator led to PEG(N3)‐b‐PNIPAM bearing an azido moiety at the diblock junction point. Finally, well‐defined ABC miktoarm star terpolymer, PEG(‐b‐PtBMA)‐b‐PNIPAM, was prepared via the click reaction of PEG(N3)‐b‐PNIPAM with monoalkynyl‐terminated PtBMA. In aqueous solution, the obtained ABC miktoarm star terpolymer self‐assembles into micelles consisting of PtBMA cores and hybrid PEG/PNIPAM coronas, which are characterized by dynamic and static laser light scattering, and transmission electron microscopy. On heating above the phase transition temperature of PNIPAM in the hybrid corona, micelles initially formed at lower temperatures undergo further structural rearrangement and fuse into much larger aggregates solely stabilized by PEG coronas. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4001–4013, 2009
Nanostructured polymer composite nanoparticles synthesized in a single step via simultaneous ROMP and ATRP under microemulsion conditions
Authors: Airaud Cédric , Ibarboure Emmanuel , Gaillard Cédric , Héroguez Valérie
Published: July 2009

Ring‐Opening Metathesis Polymerization (ROMP) and Atom‐Transfer Radical Polymerization (ATRP) were carried out simultaneously under microemulsion conditions with 1st generation Grubbs catalyst playing a double role: ROMP initiator and ATRP controlling agent. Starting from two distinct microemulsions—one containing the monomers and the other the catalyst—well‐defined composite nanoparticles with z‐average hydrodynamic diameter smaller than 50 nm were prepared. Depending on the monomers droplet composition, homopolymers blends or graft‐copolymers were synthesized in a one‐pot, one‐step, one‐catalyst approach. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4014–4027, 2009
Thermodynamic and structural analysis of highly stabilized BPTIs by single and double mutations
Authors: Islam Mohammad Monirul , Sohya Shihori , Noguchi Keiichi , Kidokoro Shun‐ichi , Yohda Masafumi , Kuroda Yutaka
Published: July 2009

Enhancing protein conformational stability is an important aspect of protein engineering and biotechnology. However, protein stabilization is difficult to rationalize as it often results from the small cumulative and intertwined effects of multiple mutations. Here, we analyzed the mechanisms behind a remarkable 13° stabilization produced by a single A14G and a double A14GA38V mutation in BPTI‐[5,55], a natively folded bovine pancreatic trypsin inhibitor variant. Differential scanning calorimetry analysis of three BPTI‐[5,55] variants (A14G, A38V, and A14GA38V) indicated that the A14G mutation stabilized the structure enthalpically, whereas the A38V stabilization was entropy driven. We also determined the structure of the A14GA38V mutant at 1.09 Å resolution, whereas the A38V variant did not crystallize, and we previously reported the A14G variant's structure (2ZJX). The overall structures of the A14G and A14GA38V variants were very similar to that of wild‐type BPTI, but small local structure perturbations around residues 14 and 38 strongly suggested potential factors contributing to the enthalpy stabilization. First, the A14G mutation displaced the local backbone structures around residues 14 and 38 by up to 0.7 Å, presumably increasing local van der Waals interactions. Next, this displacement produced steric clashes between neighboring residue's side‐chains in all but the variants containing the A14G mutation. Noteworthy, these clashes are not predicted from the wild type BPTI structure. These observations provide one of the first unambiguous analyses of how a subtle interplay between the sidechain and backbone structures can have a major effect on protein stability. Proteins 2009. © 2009 Wiley‐Liss, Inc.
ATP conformations and ion binding modes in the active site of anthrax edema factor: A computational analysis
Authors: Martínez Leandro , Laine Elodie , Malliavin Thérèse E. , Nilges Michael , Blondel Arnaud
Published: July 2009

The Edema Factor (EF), one of the virulence factors of anthrax, is an adenylyl cyclase that promotes the overproduction of cyclic‐AMP (cAMP) from ATP, and therefore perturbs cell signaling. Crystallographic structures of EF bound to ATP analogs and reaction products, cyclic‐AMP, and Pyrophosphate (PPi), revealed different substrate conformations and catalytic‐cation binding modes, one or two cations being observed in the active site. To shed light into the biological significance of these crystallographic structures, the energetics, geometry, and dynamics of the active site are analyzed using molecular dynamics simulations. The ATP conformation observed in the one‐metal‐ion structure allows stronger interactions with the catalytic ion, and ATP is more restrained than in the structure containing two Mg2+ ions. Therefore, we propose that the conformation observed in the one‐ion crystal structure is a more probable starting point for the reaction. The simulations also suggest that a C3′‐endo sugar pucker facilitates nucleophilic attack. Additionally, the two‐cation binding mode restrains the mobility of the reaction products, and thus their tendency to dissociate. Proteins 2009. © 2009 Wiley‐Liss, Inc.
Insecticidal action of mammalian galectin‐1 against diamondback moth (Plutella xylostella)
Authors: Chen Shiang Jiuun , Chen Nien‐Ting , Wang Siou‐Hua , Hsu Ju Chun , Ding Wang‐Hsien , Kuo‐Huang Ling‐Long , Huang Rong Nan
Published: July 2009

BACKGROUND: Previous studies showed that mammalian galectin‐1 (GAL1) could interact with chitosan or chitin, one component of the peritrophic membrane (PM). This finding suggests that the PM could be a target of GAL1, which prompted the authors to explore the effect of GAL1 on larval growth and its potential mechanism.

RESULTS: The development of Plutella xylostella (L.) larvae was significantly disturbed after they were fed recombinant GAL1. The histochemical structure and immunostaining pattern suggested that GAL1 treatment resulted in dose‐ and time‐dependent disruption of the microvilli and abnormalities in these epithelial cells. Ultrastructural studies showed that the PM was not present in the midgut of GAL1‐treated insects; instead, numerous bacteria were found in the lumen area. These results indicate that the protective function of the PM was disrupted by GAL1 treatment. Moreover, in vitro data showed that GAL1 interacts with chitosan/chitin in a dose‐dependent manner, and also specifically binds to the PM in vitro.

CONCLUSION: In view of the fact that the carbohydrate recognition domain of GAL1 recognises the structural motif N‐acetyl lactosamine (Gal β 1–4 GlcNAc), which is similar to that of chitin (β‐1,4 N‐acetyl‐D‐glucosamine), it is proposed that the insecticidal mechanism of GAL1 involves direct binding with chitin to interfere with the structure of the PM. Copyright © 2009 Society of Chemical Industry
Magnetic and structural study of FCCγ‐Fe precipitates in Cu
Authors: Hines W. A. , Shanthakumar P. , Huang T. , Budnick J. I. , Miller R. L. , Pease D. M. , Perry D. M.
Published: July 2009

Magnetization, X‐ray absorption fine structure, and resistivity measurements on two samples of Cu + 2.0 at% Fe are reported here. The first sample, prepared by annealing at 950 °C for 2 days followed by rapid quenching, consists of a random solid solution of Fe in Cu. The paramagnetic susceptibility follows the Curie–Weiss law 10 K ≤ T ≤ 300 K yielding an effective Fe moment of 1.9 ± 0.1 µBand a Curie temperature −2.0 ± 2.0 K. The second sample, prepared using the heat treatment above followed by a second annealing at 620 °C for 2 h, consists of face‐centered‐cubic (FCC)γ‐Fe precipitates in the Cu matrix. The formation of the Fe precipitates reduces the electronic scattering, which is reflected in the resistivity behavior. The FCC atomic short‐range order for the Fe is demonstrated with X‐ray absorption fine structure. The paramagnetic susceptibility follows the Curie–Weiss law 100 K ≤ T ≤ 300 K yielding an effective Fe moment of 1.8 ± 0.2 µBand a Curie temperature −58 ± 10 K, consistent with an antiferromagnetic (AFM) ordering. The results are discussed in the light of previous neutron investigations of the ordered magnetic structure.
Spiral structures in layered magnets
Authors: Rosenfeld E. V. , Mushnikov N. V. , Dyakin V. V.
Published: July 2009

The formation and stability of spiral magnetic structures in isotropic layered magnets have been studied under the assumption of a strong intralayer and several relatively weak interlayer exchange interactions. It was shown that all the possible magnetic structures can be derived from eigenvectors of a matrix of interlayer exchange integrals. No more than S different magnetic structures can be realized in a crystal that comprises S nonequivalent magnetic layers. Each of these structures can be presented as S nested simple spirals with an equal period, which turn about over the layers of the same type. However, not all of them are stable. In particular, in a two‐layer magnet (S = 2), there can exist two different double spirals but only one of them would be stable.
Realization of longitudinal pure spin currents in a four‐terminal parallel double‐quantum‐dot structure
Authors: Han Yu , Gong Weijiang , Wei Guozhu
Published: July 2009

Spin‐dependent electron transport properties in a parallel double‐quantum‐dot structure with four terminals are theoretically investigated by means of the nonequilibrium Green function technique. When applying a local Rashba spin–orbit interaction on an individual quantum dot and introducing a finite bias between the transverse terminals, we show that in the presence of appropriate structure parameters, apparent pure spin currents come into being in the longitudinal terminals with the same amplitude and opposite polarization directions. Besides, the polarization directions of such spin currents can be efficiently inverted by the adjustment of structure parameters.
The science of atomic engineering of chalcogenide glasses
Authors: Ovshinsky Stanford
Published: July 2009

We briefly describe how science, invention, and technology affected and stimulated an unexplored field of material science, disordered and amorphous semiconductors, which resulted in unexpected and useful new physical, electronic, and stereochemical mechanisms. Our special focus is on chalcogenide glasses and the unique electronic devices that are made from these materials.
Chalcogenide glasses in Japan: A review on photoinduced phenomena
Authors: Tanaka Keiji , Shimakawa Koichi
Published: July 2009

Research on chalcogenide glasses in Japan is historically reviewed. A focus is laid on photoinduced phenomena such as optical phase change, photodarkening, and photodoping. We also refer to electrical, photoconductive, and photonic applications.
Amorphous selenium and its alloys from early xeroradiography to high resolution X‐ray image detectors and ultrasensitive imaging tubes
Authors: Kasap Safa , Frey Joel B. , Belev George , Tousignant Olivier , Mani Habib , Laperriere Luc , Reznik Alla , Rowlands John A.
Published: July 2009

We describe the progress in the science and technology of stabilized a‐Se from its early use in xerography and xeroradiography to its present use in commercial modern flat panel X‐ray imagers and ultrasensitive video tubes which utilize impact ionization of drifting holes. Both electrons and holes can drift in stabilized a‐Se, which is a distinct advantage since X‐ray photogeneration of charge carriers occurs throughout the bulk of the photoconductive layer. An a‐Se photoconductor has to be operated at high fields to ensure that the photogeneration efficiency is sufficiently large to provide reasonable X‐ray sensitivity. However, at high fields, the dark current is unacceptably large in simple metal/a‐Se/metal devices, and special multilayer device structures need to be designed. The dark current decays with time and increases with the nominal applied field. The reduction of the dark current to a tolerable level was one of the key factors that lead to the commercialization of a‐Se X‐ray detectors. We discuss the origin of the dark current, and highlight some of the current challenges in the design of next generation detectors. We also discuss the origin of impact ionization in a‐Se, and its fruitful utilization in ultrasensitive imaging devices, including the Harpicon, which are likely to lead to new high detective quantum efficiency detectors.
Local structure of amorphous GeSbTe alloys: Ge umbrella flip vs. DFT simulations
Authors: Kolobov A. V. , Fons P. , Tominaga J.
Published: July 2009

In this paper, we discuss the structure of amorphous Ge2Sb2Te5 derived from X‐ray absorption experiments and computer simulations. We demonstrate that despite seeming differences the proposed structures are not in contradiction and refer to the same local structure.
Photocurrent measurements in chlorine‐doped amorphous selenium
Authors: Benkhedir Mohammed L. , Mansour Mohammed , Djefaflia Fahima , Brinza Monica , Adriaenssens Guy J.
Published: July 2009

Transient photocurrent (TPC) measurements have been carried out on evaporated a‐Se films doped with either 12.5 or 67 ppm of Cl and compared with analogous measurements on undoped a‐Se samples. The two doping levels lead to strikingly different resulting current traces. While the 12.5 ppm doping level weakens, but does not eliminate the signature of the two hole traps that are observed in the TPC signals of undoped a‐Se, no indication for those levels remains in the 67 ppm Cl‐doped samples. It is argued that suppression of the trap generated by the negative‐U D− centre agrees with the notion that they are being supplanted by doping‐induced Cl− centres. The enhanced density of D+ centres and accompanying cross‐linking of Se chains by those three‐fold coordinated sites leads in turn to the weakening and disappearance of the shallower hole trap ascribed to dihydral angle variations. Results from constant‐photocurrent and time‐of‐flight (TOF) experiments support this interpretation of the TPC observations.
Modelling thermally‐stimulated currents in disordered semiconductors
Authors: Main Charles
Published: July 2009

We report a computer modelling study of thermally stimulated currents in thin film semiconductors. In a multi trapping context, we examine this method as a ‘spectroscopy’ of the energy distribution of localised states. We consider so‐called ‘weak’ and ‘strong’ re‐trapping conditions, the use of non‐physical ‘effective’ attempt‐to‐escape frequencies and the effect of lifetime variation as distributions relax. We show that for strong re‐trapping in distributed states, the energy scale can be better approximated by the quasi‐Fermi level position and propose that the density of states may alternatively be computed using the easily determined derivative of the quasi‐Fermi energy with respect to temperature.
Low‐temperature amorphous silicon p–i–n photodiodes
Authors: Street Robert A. , Wong William S. , Lujan Rene
Published: July 2009

Amorphous silicon p–i–n photodiodes are important for image sensors and solar cells. The paper describes the properties of photodiodes fabricated below 200 °C on flexible plastic substrates. The increased defect density of the low‐temperature growth increases the reverse saturation current but the forward characteristics are largely unchanged. The role of the dangling bond defects in the diode characteristics is discussed.
Applying Design of Experiments to a lift test rig
Authors: Viles Elisabeth , Tanco Martín , Isasa Inge , Arteche Unai , Sagartzazu Xabier
Published: July 2009

As comfort has become an important factor in the lift industry, validated lift models are currently a significant research area. In this article, we present an analysis of a lift guiding system, which transmits vibrations to the cabin and affects passengers' comfort. The project consisted of determining the most important lift guiding system factors that affect a lift's comfort. The Design of Experiments technique was chosen as the best technique available to maximize the information gathered from the experiments. In order to carry out the experiments, a lift test rig was specially constructed in order to simulate a real installation. We screened and analyzed the influence of many factors on the response with an adapted factorial fractional design. This article shows the steps carried out in planning and analyzing the experiments, putting special emphasis on the planning during every phase of the DoE application. This research project was co‐developed by a research center, a university and a well‐known Spanish lift company. Copyright © 2009 John Wiley & Sons, Ltd.
New control charts for monitoring covariance matrix with individual observations
Authors: Memar Ahmad Ostadsharif , Niaki Seyed Taghi Akhavan
Published: July 2009

It has recently been shown that the performance of multivariate exponentially weighted mean square and multivariate exponentially weighted moving variance charts of Huwang et al. (J. Qual. Technol. 2007; 39:258–278) in monitoring the variability of a multivariate process for individual observations is better than existing schemes. Both of these control charts monitor a distinct matrix which is an estimator of the in‐control covariance matrix. Instead of using the trace, in this paper, we propose a L1‐norm and a L2‐norm‐based distance between diagonal elements of the estimators from their expected values to design new control charts in monitoring the covariance matrix of a multivariate process. The results of simulations show that employing the new control statistics significantly improve the ability of the change detection process in the covariance matrix. Copyright © 2009 John Wiley & Sons, Ltd.
Theoretical calculation of the low laying electronic states of the molecular ion RbH+
Authors: Korek M. , Hammoud S. , Harb T.
Published: July 2009

Using an ab initio method, the potential energy has been calculated for the 29 lowest molecular states of symmetries 2Σ+, 2Π, 2Δ for the molecular ion RbH+. The calculation is based on nonempirical pseudopotentials and parameterized ℓ‐dependent polarization potentials. Gaussian basis sets have been used for both atoms. The spectroscopic constants for 18 electronic sates have been calculated by fitting the calculated energy values to a polynomial in terms of the internuclear distance R. Through the canonical functions approach the eigenvalue Ev, the abscissas of the corresponding turning points (Rmin and Rmax) and the rotational constants Bv have been calculated up to 24 vibrational levels for the considered bound states. The comparison of the present results with those available in literature shows a very good agreement. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
A theoretical study on three conformational structures of 2,6‐distyrylpyridine
Authors: Melendez F. J. , Urzúa Omar , Percino M. Judith , Chapela Victor M.
Published: July 2009

Ab initio methods at the levels HF/cc‐pVDZ, HF/6‐31G(d,p), MP2/cc‐pVDZ, and MP2/6‐31G(d,p), as well as methods based on density functional theory (DFT) employing the hybrid functional B3LYP with the basis sets cc‐pVDZ and 6‐31G(d,p), have been applied to study the conformers of 2,6‐distyrylpyridine. Bond distances, bond angles, and dihedral angles have been calculated at the B3LYP level. The calculated values were in good agreement with those measured by X‐ray diffraction analysis of 2,6‐distyrylpyridine. The values calculated using the Hartree‐Fock method and second‐order perturbation theory (MP2) were inconsistent. The optimized lowest‐energy geometries were calculated from the reported X‐ray structural data by the B3LYP/cc‐pVDZ method. Three conformations, A, B, and C, were proposed for 2,6‐distyrylpyridine. Calculations at the three levels of theory indicated that conformation A was the most stable structure, with conformations C and B being higher in energy by 1.10 and 2.57 kcal/mol, respectively, using the same method and basis function. The same trend in the relative energies of the three possible conformations was observed at the two levels of theory and with the different basis sets employed. The reported X‐ray data were utilized to optimize total molecular energy of conformation A at the different calculation levels. The bond lengths, bond angles, and dihedral angles were then obtained from the optimized geometries by ab initio methods and by applying DFT using the two basis functions cc‐pVDZ and 6‐31G(d,p). The values were analyzed and compared. The calculated total energies, the relative energies of the molecular orbitals, the gap between them, and the dipole moment for each conformational structure proposed for 2,6‐distyrylpyridine are also reported. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
Orientation of endohedral H2, CO, and LiH inside heptagon‐containing C58 and C58H18
Authors: Sun Lili , Chang Yingfei , Tang Shuwei , Wang Rongshun
Published: July 2009

Three H2@C58Hx, six CO@C58Hx, and six LiH@C58Hx (x = 0 and 18) complexes were optimized using B3LYP/6‐31G* method. The results show that both C58 and C58H18 destabilize nonpolar H2 and weakly polar CO, and stabilize strongly polar LiH inside their cages. Three H2@C58Hx (x = 0 and 18) complexes are nearly equivalent in energy, and CO orients the longest direction of cage because of spatial repulsion between them in the most stable CO@C58Hx (x = 0 and 18) isomers. Orientation of LiH inside C58Hx (x = 0 and 18) cages is determined by dipole‐induced dipole attractive interaction between them, and this attraction is especially significant in LiH@C58H18 complexes. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
δ and σ vs. π conflicting aromatic pentagonal ring of tungsten with a planar pentacoordinate carbon at the ring center
Authors: Yamaguchi Wataru
Published: July 2009

Density functional theory calculations have predicted a planar dicationic nanocluster CW consisting of a five‐membered tungsten ring and a planar pentacoordinate carbon atom located at the ring center. Although the regular‐pentagonal tungsten ring has strong aromaticity as a whole in terms of a magnetic criterion, detailed analyses have suggested that it is conflicting d‐orbital aromaticity in which δ‐ and σ‐aromaticity coexist with relatively weak π‐antiaromaticity. The system is unique in that δ‐aromaticity is involved in conflicting aromaticity, as well as being found in a conjugated ring consisting of more than three metal atoms. Although the planar pentagonal cluster ion is not the global minimum on the potential energy surface of CW, molecular dynamics simulations suggest that the planar species is fairly stable under mild conditions. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
Superconductivity in cuprates: Details of electron phonon coupling
Authors: Larsson Sven
Published: July 2009

The Bardeen‐Cooper‐Schrieffer (BCS) model explains superconductivity (SC) as due to correlation between electronic momentum and nuclear momentum (phonons) in a free electron gas. The BCS model lacks chemical specificity, however, since the coupling mechanism is left unspecified. After the discovery of high TC superconductivity in 1986 it was concluded that electron–phonon interactions are insufficient to explain electron pairing. A large part of theoretical research has since been aiming at finding another mechanism that would allow us to consider the superconducting system as a gas of charged free bosons. However, there appears to be no reason to assume free electrons in oxides. In this article the free‐electron criterion is therefore replaced by the criterion that a pair of electrons can move freely between sites without resistance, i.e., without activation energy. Electron pair transfer is treated in a many‐electron real space approach using standard mixed‐valence theories. Mott‐Hubbard‐U is strictly defined, its dependence on breathing mode coordinates analyzed, and the connection between U and the energy gap for superconductivity clarified. d‐wave gap anisotropy is found to be consistent with the general atomic level model presented here. Softening of phonon half‐breathing modes in inelastic neutron scattering (INS) is connected to mixed‐valency. The fundamental vibronic interaction between spin density wave (SDW) and charge density wave (CDW) states leads to a new phase with energy gap and electron pair carriers that can only be the superconducting phase. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
Benchmark calculations for molecules in the gas phase: State‐of‐the‐art coupled‐cluster computations
Authors: Puzzarini Cristina , Barone Vincenzo
Published: July 2009

Implementation of very accurate ab initio methods on the one hand and improvements in computer facilities on the other hand allow the determination of structural, thermochemical, and spectroscopic properties of small‐ to medium‐sized molecules to a very high accuracy. The predictive capabilities have become so high that theoretical calculations can guide, support, and even challenge experimental determinations. Therefore, nowadays ab initio calculations are suitable for benchmarking purposes, even for quite large systems. To perform benchmark calculations, highly correlated methods, such as the coupled cluster ones, should be employed in conjunction with extrapolative and additive techniques to account for basis set and wave function truncation errors as well as to include important corrections, such as those related to core correlation and relativistic effects. Some illustrative examples are presented. The comparison of the computed data with experimental results allows us to show how quantum‐chemical computations are able to either accurately predict experimental data or cast doubts on them. Perspectives for extension of extrapolation techniques to the structures and properties of open‐shell systems with an effectiveness and reliability comparable with that well documented for closed‐shell systems are also discussed. Finally, perspectives for wider application of benchmark calculations are addressed. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
Hydrogen bonding interaction between 1,4‐dioxane and water
Authors: Chaudhari Ajay
Published: July 2009

This work reports an interaction of 1,4‐dioxane with one, two, and three water molecules using the density functional theory method at B3LYP/6‐311++G* level. Different conformers were studied and the most stable conformer of 1,4‐dioxane‐(water)n (n = 1–3) complex has total energies −384.1964038, −460.6570694, and −537.1032381 hartrees with one, two, and three water molecules, respectively. Corresponding binding energy (BE) for these three most stable structures is 6.23, 16.73, and 18.11 kcal/mol. The hydrogen bonding results in red shift in OO stretching and CC stretching modes of 1,4‐dioxane for the most stable conformer of 1,4‐dioxane with one, two, and three water molecules whereas there was a blue shift in CO symmetric stretching and CO asymmetric stretching modes of 1,4‐dioxane. The hydrogen bonding results in large red shift in bending mode of water and large blue shift in symmetric stretching and asymmetric stretching mode of water. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
A DFT investigation of dissociation of nitrous acid, transformation of its monomeric isomers, their dimeric isomers, and dimerization
Authors: Ruangpornvisuti Vithaya
Published: July 2009

The structure optimization of the monomeric isomers of the nitrous acid HONO, their cyclic dimers (HONO)2, and transition states of their transformations has been carried out using the density functional theory calculations at the B3LYP/6‐311++G(d,p) and B3LYP/aug‐cc‐pVQZ levels of theory. Three monomeric isomers (c, t, and z isomers) and six dimeric isomers (cc, ct, cz, tt, zz, and tz isomers) were found. Dissociation of the most stable of the HONO isomer (t isomer) was investigated and its rate constant was obtained at the UB3LYP/aug‐cc‐pVQZ level. Energetics, thermodynamic properties, rate, and equilibrium constants of the monomeric and dimeric isomerizations of the nitrous acid were obtained. Dimerization energies, enthalpies, and free energies of the dimeric isomers, (HONO)2 were also obtained. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
Structural alignment using the generalized Euclidean distance between conformations
Authors: Mohazab Ali R. , Plotkin Steven S.
Published: July 2009

The usual Euclidean distance may be generalized to extended objects such as polymers or membranes. Here, this distance is used for the first time as a cost function to align structures. We examined the alignment of extended strands to idealized beta‐hairpins of various sizes using several cost functions, including RMSD, MRSD, and the minimal distance. We find that using minimal distance as a cost function typically results in an aligned structure that is globally different than that given by an RMSD‐based alignment. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Salt Rejection and Water Transport Through Boron Nitride Nanotubes
Authors: Hilder Tamsyn A. , Gordon Daniel , Chung Shin‐Ho
Published: July 2009

Nanotube‐based water‐purification devices have the potential to transform the field of desalination and demineralization through their ability to remove salts and heavy metals without significantly affecting the fast flow of water molecules. Boron nitride nanotubes have shown superior water flow properties compared to carbon nanotubes, and are thus expected to provide a more efficient water purification device. Using molecular dynamics simulations it is shown that a (5, 5) boron nitride nanotube embedded in a silicon nitride membrane can, in principle, obtain 100% salt rejection at concentrations as high as 1 M owing to a high energy barrier while still allowing water molecules to flow at a rate as high as 10.7 water molecules per nanosecond (or 0.9268 L m−2 h−1). Furthermore, ions continue to be rejected under the influence of high hydrostatic pressures up to 612 MPa. When the nanotube radius is increased to 4.14 Å the tube becomes cation‐selective, and at 5.52 Å the tube becomes anion‐selective.
C957T polymorphism of dopamine D2 receptor gene affects striatal DRD2 in vivo availability by changing the receptor affinity
Authors: Hirvonen Mika M. , Laakso Aki , Någren Kjell , Rinne Juha O. , Pohjalainen Tiina , Hietala Jarmo
Published: July 2009

The C957T polymorphism of the human dopamine D2 receptor gene (DRD2) regulates DRD2 availability in striatum in vivo. Specifically, the T allele predicts high DRD2 availability in healthy volunteers (T/T>T/C>C/C). However, this finding was unexpected as in vitro the T allele is associated with a decrease inDRD2mRNA stability and synthesis of the receptor through a putative alteration in the receptor mRNA folding. To elucidate further how changes in DRD2 density (Bmax) and affinity (KD) contribute to the differences in DRD2 availability between the C957T genotypes, we studied these parameters separately in a sample of 45 healthy volunteers. The subjects had two PET scans with [11C]raclopride (high and low specific radioactivity scans) for the estimation ofBmaxandKD, and were genotyped for the C957T. Moreover, the role of the related and previously studied functional TaqIA polymorphism of ankyrin repeat and kinase domain containing 1 (ANKK1) gene was reassessed for comparative purposes. The results indicate that the C957T increased binding potential by decreasing DRD2KD(C/C>C/T>T/T), whileBmaxwas not significantly altered. These preliminary findings indicate that the C957T genotype‐dependent changes in DRD2 availability are driven by alterations in receptor affinity and putatively in striatal dopamine levels. This mechanism seems to differ from that observed previously for theANKK1gene TaqIA polymorphism, where the minor allele (A1) affects DRD2 availability predominantly by changingBmax. The hypothesis that the two SNPs may have independent effects on dopamine neurotransmission needs to be further tested. Synapse 63:907–912, 2009. © 2009 Wiley‐Liss, Inc.
Differential effects of topiramate on prefrontal glutamatergic transmission when combined with raclopride or clozapine
Authors: Jardemark Kent E. , Konradsson Åsa , Schilström Björn , Marcus Monica M. , Svensson Torgny H.
Published: July 2009

Treatment with topiramate may improve negative symptoms in schizophrenia when added to typical antipsychotic drugs (APDs) but not to clozapine. Both dopaminergic and glutamatergic transmissions in the medial prefrontal cortex (mPFC) are facilitated by atypical, but not typical, APDs, which is thought to improve negative symptoms and cognitive dysfunction in schizophrenia. Our previous results show that topiramate increases prefrontal dopamine (DA) outflow when added to the D2/3receptorantagonist raclopride. Here, using intracellular recording in vitro, we investigated the effects of topiramate on glutamatergic neurotransmission in the rat mPFC, both when given alone and in combination with raclopride or clozapine. Neither topiramate nor raclopride alone had any effect onN‐methyl‐D‐aspartate (NMDA)‐induced currents in pyramidal cells of the mPFC. However, the combination of topiramate and raclopride facilitated the NMDA‐induced currents, and this effect was blocked by the D1receptor antagonist SCH23390. Topiramate also facilitated the effect of a submaximal, but inhibited the effect of a maximal, concentration of clozapine on these currents. The effect of combined topiramate and a submaximal concentration of clozapine could be blocked by SCH23390. In addition, combined topiramate and raclopride facilitated excitatory postsynaptic potentials. In contrast, topiramate inhibited clozapine's facilitating effect on these potentials. These data may help explain the improvement of negative symptoms when topiramate is used as adjunctive therapy in schizophrenic patients receiving typical APDs, but they may also shed light on the observed deterioration of symptoms when topiramate is added to full dose clozapine. Synapse 63:913–920, 2009. © 2009 Wiley‐Liss, Inc.
Inherited disorders in the conversion of methionine to homocysteine
Authors: Barić Ivo
Published: July 2009

During the last decade much important new information relating to the metabolic pathway from methionine to homocysteine has been gained. Interest has been stimulated by the discovery of two novel disorders, glycine N‐methyltransferase deficiency and S‐adenosylhomocysteine hydrolase deficiency. Another disorder in this pathway, methionine adenosyltransferase deficiency, has been increasingly detected, thanks to the expansion of newborn screening programmes by tandem mass spectrometry technology. These significant steps allow important insight into the pathogenesis of these three disorders, as well as into the mechanisms of damage to various organs (liver, brain, muscle) and point to the relevance of these disorders for crucial biological processes such as methylation, transsulfuration or carcinogenesis in mammals, the pathogenesis of numerous pathological conditions, in particular those associated with hyperhomocysteinaemia, the action and possible toxicity of some drugs or consequences of nutritional variations. This review summarizes current knowledge of three inherited disorders in this metabolic pathway and draws attention to their much broader significance for human health and understanding of important biological processes.