bluuebunny/crossref_metadata_2025 huggingface dataset:
Roles of K151 and D180 in L‐2‐haloacid dehalogenase from Pseudomonas sp. YL: Analysis by molecular dynamics and ab initio fragment molecular orbital calculations
Authors: Nakamura Takashi , Yamaguchi Azusa , Kondo Hirotaka , Watanabe Hirofumi , Kurihara Tatsuo , Esaki Nobuyoshi , Hirono Shuichi , Tanaka Shigenori
Published: April 2009

L‐2‐haloacid dehalogenase (L‐DEX) catalyzes the hydrolytic dehalogenation of L‐2‐haloalkanoic acids to produce the corresponding D‐2‐hydroxyalkanoic acids. This enzyme is expected to be applicable to the bioremediation of environments contaminated with halogenated organic compounds. We analyzed the reaction mechanism of L‐DEX from Pseudomonas sp. YL (L‐DEX YL) by using molecular modeling. The complexes of wild‐type L‐DEX YL and its K151A and D180A mutants with its typical substrate, L‐2‐chloropropionate, were constructed by docking simulation. Subsequently, molecular dynamics (MD) and ab initio fragment molecular orbital (FMO) calculations of the complexes were performed. The ab initio FMO method was applied at the MP2/6‐31G level to estimate interfragment interaction energies. K151 and D180, which are experimentally shown to be important for enzyme activity, interact particularly strongly with L‐2‐chloropropionate, catalytic water, nucleophile (D10), and with each other. Our calculations suggest that K151 stabilizes substrate orientation and balances the charge around the active site, while D180 stabilizes the rotation of the nucleophile D10, fixes catalytic water around D10, and prevents K151 from approaching D10. Further, D180 may activate catalytic water on its own or with K151, S175, and N177. These roles are consistent with the previous results. Thus, MD and ab initio FMO calculations are powerful tools for the elucidation of the mechanism of enzymatic reaction at the molecular level and can be applied to other catalytically important residues. The results obtained here will play an important role in elucidating the reaction mechanism and rational design of L‐DEX YL with improved enzymatic activity or substrate specificity. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2009
Survival responses of human embryonic stem cells to DNA damage
Authors: Filion Tera M. , Qiao Meng , Ghule Prachi N. , Mandeville Matthew , van Wijnen Andre J. , Stein Janet L. , Lian Jane B. , Altieri Dario C. , Stein Gary S.
Published: April 2009

Pluripotent human embryonic stem (hES) cells require mechanisms to maintain genomic integrity in response to DNA damage that could compromise competency for lineage‐commitment, development, and tissue‐renewal. The mechanisms that protect the genome in rapidly proliferating hES cells are minimally understood. Human ES cells have an abbreviated cell cycle with a very brief G1 period suggesting that mechanisms mediating responsiveness to DNA damage may deviate from those in somatic cells. Here, we investigated how hES cells react to DNA damage induced by ionizing radiation (IR) and whether genomic insult evokes DNA repair pathways and/or cell death. We find that hES cells respond to DNA damage by rapidly inducing Caspase‐3 and ‐8, phospho‐H2AX foci, phosphorylation of p53 on Ser15 and p21 mRNA levels, as well as concomitant cell cycle arrest in G2 based on Ki67 staining and FACS analysis. Unlike normal somatic cells, hES cells and cancer cells robustly express the anti‐apoptotic protein Survivin, consistent with the immortal growth phenotype. SiRNA depletion of Survivin diminishes hES survival post‐irradiation. Thus, our findings provide insight into pathways and processes that are activated in human embryonic stem cells upon DNA insult to support development and tissue regeneration. J. Cell. Physiol. 220: 586–592, 2009. © 2009 Wiley‐Liss, Inc.
Mercury(II) removal using polymer inclusion membranes containing Cyanex 471X
Authors: Mercader‐Trejo Flora E , Rodríguez de San Miguel Eduardo , de Gyves Josefina
Published: April 2009

BACKGROUND: Regulatory controls to limit mercury emissions in waters have impacted on the development of membrane extraction‐based methodologies for its separation. The specific advantages (effective carrier immobilization, easy preparation, versatility, and good mechanical properties) of polymer inclusion membranes (PIMs) make them suitable for this purpose. In this work a novel procedure using PIMs for mercury separation with a commercial available extractant (Cyanex 471X) is described and evaluated through the determination of the efficiency parameters (permeability, selectivity, stability) and membrane characterization.

RESULTS: Using a membrane composed of 30% cellulose triacetate (CTA), 60% 2‐nitrophenyl octyl ether (NPOE), and 10% w/w Cyanex 471X a 0.1 mmol dm−3 Hg(II) solution prepared in 0.01 mol dm−3 HCl was transported to a 0.05 mol dm−3 NaCl solution at pH 12.3 with permeability values in the feed and strip phases of 0.25 and 0.15 cm min−1, respectively. A diffusive Fickian‐type mechanism was inferred from the results. High separation factors ranging between 2 and 5900, less than 11% of competing metal ions transported, active transport of the metal ion and a successful reuse of the PIM were achieved.

CONCLUSION: Optimized PIMs using Cyanex 471X represent an interesting alternative for Hg(II) removal from waters showing high efficiency factors and easy implementation. Copyright © 2009 Society of Chemical Industry
Organization of the vitelline envelope in ovarian follicles of Torpedo marmorata Risso, 1810 (Elasmobranchii: Torpediniformes)
Authors: Prisco Marina , Del Giudice Giuseppina , Agnese Marisa , Ricchiari Loredana , Campanella Chiara , Andreuccetti Piero
Published: April 2009

In Torpedo marmorata, the vitelline envelope (VE), an extracellular envelope surrounding the growing oocyte, consists of fibrils and amorphous materials that are deposited in the perivitelline space starting from the initial steps of oocyte growth. SDS‐PAGE analysis of the isolated and purified VE reveals that it consists of different glycoproteins. Furthermore, our investigations showed that the 120 and 66 kDa glycoproteins are positive to an antibody directed against gp69/64 of the Xenopus laevis VE and are synthesized under the control of 17β‐estradiol in the liver, that, together follicle cells and the oocyte, is the biosynthetic site of VE components. J. Exp. Zool. (Mol. Dev. Evol.) 312B:714–721, 2009. © 2009 Wiley‐Liss, Inc.
Grünbaum colorings of toroidal triangulations
Authors: Albertson Michael O. , Alpert Hannah , belcastro sarah‐marie , Haas Ruth
Published: April 2009

We prove that if G is a triangulation of the torus and χ(G)≠5, then there is a 3‐coloring of the edges of G so that the edges bounding every face are assigned three different colors. © 2009 Wiley Periodicals, Inc. J Graph Theory 63: 68–81, 2010
On the conjecture for certain Laplacian integral spectrum of graphs
Authors: Das Kinkar Ch. , Lee Sang‐Gu , Cheon Gi‐Sang
Published: April 2009

Let G be a simple graph of order n with Laplacian spectrum {λn, λn−1, …, λ1} where 0=λn≤λn−1≤⋅≤λ1. If there exists a graph whose Laplacian spectrum is S={0, 1, …, n−1}, then we say that S is Laplacian realizable. In 6, Fallat et al. posed a conjecture that S is not Laplacian realizable for any n≥2 and showed that the conjecture holds for n≤11, n is prime, or n=2, 3(mod4). In this article, we have proved that (i) if G is connected and λ1=n−1 then G has diameter either 2 or 3, and (ii) if λ1=n−1 and λn−1=1 then both G and Ḡ, the complement of G, have diameter 3. © 2009 Wiley Periodicals, Inc. J Graph Theory 63: 106–113, 2010
Increasing the accuracy of mass isotopomer analysis through calibration curves constructed using biologically synthesized compounds
Authors: Shen Tie , Shen Weiqun , Xiong Ying , Liu Haiyan , Zheng Haoran , Zhou Hong , Rui Bin , Liu Jianping , Wu Jihui , Shi Yunyu
Published: April 2009

Mass isotopomer analysis is an important technique to measure the production and flow of metabolites in living cells, tissues, and organisms. This technique depends on accurate quantifications of different mass isotopomers using mass spectrometry. Constructing calibration curves using standard samples is the most universal approach to convert raw mass spectrometry measurements into quantitative distributions of mass isotopomers. Calibration curve approach has been, however, of very limited use in comprehensive analyses of biological systems, mainly suffering from the lack of extensive range of standard samples with accurately known isotopic enrichment. Here, we present a biological method capable of synthesizing specifically labeled amino acids. These amino acids have well‐determined and estimable mass isotopomer distributions and thus can serve as standard samples. In this method, the bacterium strain Methylobacterium salsuginis sp. nov. was cultivated with partially 13C‐labeled methanol as the only carbon source to produce 13C‐enriched compounds. We show that the mass isotopomer distributions of the various biosynthesized amino acids are well determined and can be reasonably estimated based on proposed binomial approximation if the labeling state of the biomass reached an isotopic steady state. The interference of intramolecular inhomogeneity of 13C isotope abundances caused by biological isotope fractionation was eliminated by estimating average 13C isotope abundance. Further, the predictions are tested experimentally by mass spectrometry (MS) spectra of the labeled glycine, alanine, and aspartic acid. Most of the error in mass spectrometry measurements was less than 0.74 mol% in the test case, significantly reduced as compared with uncalibrated results, and this error is expected to be less than 0.4 mol% in real experiment as revealed by theoretical analysis. Copyright © 2009 John Wiley & Sons, Ltd.
Microfluidic chips for mass spectrometry‐based proteomics
Authors: Lee Jeonghoon , Soper Steven A. , Murray Kermit K.
Published: April 2009

Microfluidic devices coupled to mass spectrometers have emerged as excellent tools for solving the complex analytical challenges associated with the field of proteomics. Current proteome identification procedures are accomplished through a series of steps that require many hours of labor‐intensive work. Microfluidics can play an important role in proteomic sample preparation steps prior to mass spectral identification such as sample cleanup, digestion, and separations due to its ability to handle small sample quantities with the potential for high‐throughput parallel analysis. To utilize microfluidic devices for proteomic analysis, an efficient interface between the microchip and the mass spectrometer is required. This tutorial provides an overview of the technologies and applications of microfluidic chips coupled to mass spectrometry for proteome analysis. Various approaches for combining microfluidic devices with electrospray ionization (ESI) and matrix‐assisted laser desorption/ionization (MALDI) are summarized and applications of chip‐based separations and digestion technologies to proteomic analysis are presented. Copyright © 2009 John Wiley & Sons, Ltd.
DC and small‐signal comparison of horizontal emitter designs of InGaP/GaAs heterojunction bipolar transistors
Authors: López‐González Juan M.
Published: April 2009

This paper describes the DC and small‐signal performance of two InGaP/GaAs heterojunction bipolar transistors (HBTs) that have the same chip size. This is done in order to compare emitter–base designs using the TCAD ATLAS device simulator. The HBT devices analyzed have the same cutoff and maximum frequencies but significant differences are observed in other characteristics such as base–emitter turn‐on voltage, saturation collector–emitter voltage, forward current gain, maximum transducer gain and maximum stable gain. Copyright © 2009 John Wiley & Sons, Ltd.
The regime shift in the early 1980s of spring precipitation in Korea
Authors: Choi Ki‐Seon , Kim Do‐Woo , Byun Hi‐Ryong
Published: April 2009

The change‐point analysis demonstrates that there is a regime shift in the spring precipitation in Korea in 1980–1981. The total spring precipitation in the years post‐1980 showed a distinct decrease compared to the years pre‐1980. This phenomenon of reduced spring precipitation was particularly dominant in the southwestern regions of the Sobaek Mountain range in Korea. This phenomenon was also noticed in China and Japan, excluding south China. One of the major causes for this decrease in spring precipitation was the increased snow depth in the mid‐latitude regions of continental East Asia. This resulted in a strengthened cold anticyclone over continental East Asia and a relatively weakened subtropical anticyclone over the western North Pacific, thus forcing a continuation of the typical winter pressure pattern of ‘high‐West and low‐East’ in East Asia from preceding winter into current spring. The strengthened northerlies from this zonal pressure pattern played a significant role in restricting the northern movement of the subtropical anticyclone and preventing the inflow of warm and humid air into Korea. Copyright © 2009 Royal Meteorological Society
Seasonal variations in polyphenols and lipoic acid in fruits of tomato irrigated with sea water
Authors: Incerti Annalisa , Navari‐Izzo Flavia , Pardossi Alberto , Izzo Riccardo
Published: April 2009

BACKGROUND: Polyphenols and lipoic acid, due to their functions of antioxidant and free radical scavengers, are universally recognized as beneficial for preventing widespread human diseases, including cancer, and cardiovascular and cerebrovascular pathologies. In addition, they contribute to the determination of food taste and colour. These compounds were determined in tomato fruits (Solanum lycopersicum L., cv. Daniela) picked at red‐ripe stage during spring and autumn from tomato plants grown in rockwool slabs in a greenhouse in nutrient solutions with either groundwater or dilute sea water.

RESULTS: Compared with groundwater, total phenolic acids, flavonoids and dihydrolipoic acid in tomato plants irrigated with sea water showed a decrease during spring and an increase during autumn. The interaction between sea water and season played a significant role in polyphenol and lipoic acid production.

CONCLUSION: The consumption of polyphenols and lipoic acid is related to oxidative processes, which could be induced by natural physiological processes or more by environmental changes such as salinity or high irradiance. The lower presence of these antioxidants, observed in spring, may be a consequence of the more noxious levels of oxidative stress induced by the high salinity treatment when applied under a higher irradiance, typical conditions of spring in comparison to autumn. Copyright © 2009 Society of Chemical Industry
Assessment for fungal, mycotoxin and insect spoilage in maize stored for human consumption in Zambia
Authors: Kankolongo Muimba A , Hell Kerstin , Nawa Irene N
Published: April 2009

BACKGROUND:Maize constitutes the main staple food and most important crop grown in Zambia. However, maize incurs considerable losses both in field and storage due to pathogens and insects. Some of the pathogens and resultant mycotoxins reduce the nutritional quality of the product. Mycotoxins are toxigenic fungal compounds that can cause cancer and suppress growth. In spite of this health hazard, there has been very little research to document their occurrence. Maize grains stored for human consumption were sampled from different agro‐ecosystems (forest, valley and plateau areas) of three agroecological zones (high, mid and low altitude).

RESULTS:Several fungal genera were recovered among whichAspergillus flavus, A. niger, Fusarium verticillioides, F. solani, Rhizopus stoloniferandPenicilliumspp. were prevalent. The weevilSitophilus zeamaisand the larger grain borerProstephanus truncatuswere the most damaging. Enzyme‐linked immunosorbent assay (ELISA) tests yielded fumonisins and aflatoxins ranging between 0.02 and 21.44 ppm, and 0.7 and 108.39 ppb in 96.4% and 21.4% of samples, respectively. Fumonisin was more pronounced in villages in forest areas whereas aflatoxin was highest in valley and forest areas in Zone II.

CONCLUSION:Strategic interventions to curtail fungal, mycotoxin and insect contamination should be directed towards improved agronomic and post‐harvest practices of maize from fields to consumers. Copyright © 2009 Society of Chemical Industry
Farmers' perception of environmental degradation and their adoption of improved management practices in Alxa, China
Authors: Wei Y. P. , Chen D. , White R. E. , Willett I. R. , Edis R. , Langford J.
Published: April 2009

The environment and the natural resource base have been severely degraded in Alxa League, western Inner Mongolia, China, over the past half‐century. This study reports surveys that reveal farmers' perceptions of environmental degradation and their adoption of improved management practices in this poor and remote desert region. Surveys were made in villages that had been engaged in a large environmental rehabilitation and management project [Alxa League environmental rehabilitation and management project (ALERMP)] and those that had not. The survey results showed that farmers perceived environmental degradation in terms of increased frequency and severity of sandstorms, movement of sand dunes, deterioration of pasture quality and declines in groundwater depth and quality. Farmers had low adoption rates for improved management practices, ranging from zero to a maximum of 28·5 per cent for the most adopted practice. A Tobit model analysis showed that the education level of farmers, the availability of extension services and whether farmers had participated in ALERMP were highly significantly correlated with the farmers' perception of degradation. The farmers' adoption of improved management practices was found to be significantly correlated only with whether they had participated in ALERMP. This shows that specific extension activities of the type possible in large and well‐funded projects are required if farmers are to recognise degradation and adopt improved management practices. The promotion of farmer education and strengthening of extension services are recommended as the best policy strategies for improving environmental management in this region. Copyright © 2009 John Wiley & Sons, Ltd.
Explicit polynomial preserving trace liftings on a triangle
Authors: Ainsworth Mark , Demkowicz Leszek
Published: April 2009

We give an explicit formula for a right inverse of the trace operator from the Sobolev space H1(T) on a triangle T to the trace space H1/2(∂T) on the boundary. The lifting preserves polynomials in the sense that if the boundary data are piecewise polynomial of degree N, then the lifting is a polynomial of total degree at most N and the lifting is shown to be uniformly stable independently of the polynomial order. Moreover, the same operator is shown to provide a uniformly stable lifting from L2(∂T) to H1/2(T). Finally, the lifting is used to construct a uniformly bounded right inverse for the normal trace operator from the space H(div; T) to H–1/2(∂T) which also preserves polynomials. Applications to the analysis of high order numerical methods for partial differential equations are indicated (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Extension of bounded vector‐valued functions
Authors: Frerick Leonhard , Jordá Enrique , Wengenroth Jochen
Published: April 2009

In this paper we consider extensions of bounded vector‐valued holomorphic (or harmonic or pluriharmonic) functions defined on subsets of an open set Ω ⊂ ℝN. The results are based on the description of vector‐valued functions as operators. As an application we prove a vector‐valued version of Blaschke's theorem (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On some local property of the shape of interfaces for the porous media equation
Authors: Hayasida Kazuya
Published: April 2009

We consider the porous media equation with absorption for various conditions and prove that the shape of ist interface never becomes strongly upward convex. For this sake we derive an improperly posed estimate for solutions of the porous media equation for the non‐characteristic Cauchy problem (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Decomposition for Morrey type Besov–Triebel spaces
Authors: Wang Henggeng
Published: April 2009

In this paper, the author establishes the decomposition of Morrey type Besov–Triebel spaces in terms of atoms and molecules concentrated on dyadic cubes, which have the same smoothness and cancellation properties as those of the classical Besov–Triebel spaces. The results extend those of M. Frazier, B. Jawerth for Besov–Triebel spaces and those of A. L. Mazzucato for Besov–Morrey spaces (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
1H NMR discrimination of CHF4226.01 diastereoisomers in DMSO‐d6
Authors: Capacchi Silvia , Lipreri Milco , Rizzi Andrea , Caló Claudia , Peveri Tiziana , Catinella Silvia
Published: April 2009

Two diastereoisomers CHF4226.01 (R, R) and CHF4232.01 (S, R), differing for a chiral center, have been studied to investigate their possible discrimination using NMR. 1D NMR and 2D NMR experiments, such as COSY, NOESY and ROESY, were performed on pure isomers and on the association complexes formed in the presence of the chiral reagent (S)‐(−)‐1‐(2‐napthyl)ethylamine (S‐NEA). Moreover, computational studies, concerning conformational analysis and molecular dynamics, were started and supported the NMR results. Copyright © 2009 John Wiley & Sons, Ltd.
T2 relaxation measurement with solvent suppression and implications to solvent suppression in general
Authors: Hoffmann Markus M. , Sobstyl Hanna S. , Badali Vincent A.
Published: April 2009

A number of suppression pulse sequences including Excitation Sculpting and WATERGATE were incorporated into the standard Carr‐Purcell‐Meiboom‐Gill (CPMG) program for T2 measurement and experimentally evaluated. The chosen suppression schemes were of varying complexity encompassing pulse program elements, such as presaturation, gradients, and selective pulses, which are typically utilized for solvent suppression. The quality of the spectral data and the accuracy of T2 measurements of the investigated suppression schemes were evaluated using three aqueous samples with increasing proton content in the water solvent, i.e. by volume 100% D2O, 80/20% D2O/H2O, and 20/80% D2O/H2O. For signals removed from the water signal, the T2 values were generally very consistent between all pulse sequences tested. T2 measurements can be unreliable for signals too close to the water signal such that they are significantly suppressed as well. Their intensity may actually grow initially through cross relaxation that transfers magnetization back to the solute signal. In turn, this relaxation phenomenon can be exploited to improve the spectral quality of conventional solvent suppression schemes. In favorable cases, even signals that are completely masked by the water signal can be recovered by adding a carefully chosen number of spin echoes with optimized evolution time to conventional water suppression pulse programs, such as Excitation Sculpting or WATERGATE. Copyright © 2009 John Wiley & Sons, Ltd.
Hyperelastic modelling of small‐strain stiffness anisotropy of cyclically loaded sand
Authors: Gajo A.
Published: April 2009

Experimental evidence shows that soil stiffness at very small strains is strongly anisotropic and depends on the stress level and void ratio. In particular, stiffness anisotropy varies considerably in sand when subjected to cyclic loading, following the stress cycles applied. To model this behaviour, an innovative hyperelastic formulation based on the elastoplastic coupling is incorporated in a new kinematic hardening elastoplastic model. The proposed hyperelastic–plastic model is the first to be capable of correctly simulating all aspects of the small‐strain behaviour of granular materials subjected to monotonic and cyclic loads. This hyperelastic formulation is generally applicable to any elastoplastic model. Copyright © 2009 John Wiley & Sons, Ltd.
The clinical and urodynamic results of a 3‐month percutaneous posterior tibial nerve stimulation treatment in patients with multiple sclerosis‐related neurogenic bladder dysfunction
Authors: Kabay Sahin , Kabay Sibel Canbaz , Yucel Mehmet , Ozden Hilmi , Yilmaz Zahide , Aras Ozgen , Aras Bahar
Published: April 2009

Aim

The aim of this study was to investigate the effect of PTNS after 12 weeks, on the urodynamic findings in the Multiple Sclerosis (MS) patients with neurogenic detrusor overactivity (NDO).

Methods

A total of 19 MS patients with NDO were enrolled in the study. Urodynamic studies before and after 12 weeks PTNS were performed. PTNS was applied unilaterally from the medial malleolus and posterior to the edge of the tibia by using charge‐compensated 200 µs pulses with a pulse rate of 20 Hz, weekly, during 3 months. The effects of PTNS on urodynamic variables were compared of baseline and after PTNS data in MS patients.

Results

Mean volume at the first involuntary detrusor contraction (1st IDCV) on standard cystometry was 124.2±37.6 ml, while it was 217.5±66.4 mL after PTNS. Mean maximum cystometric capacity (MCC) on standard cystometry was 199.7±29.3 mL, while it was 266.8±36.9 mL after stimulation. The improvements in the 1st IDCV and MCC were statistically significant after stimulation. Mean Pdetmax at first involuntary detrusor contraction, maximal detrusor pressure at maximum cystometric capacity, detrusor pressure at maximal flow (PdetQmax) and maximal flow rate (Qmax) were statistically significant after PTNS for 12 weeks.

Conclusions

These results have demonstrated that PTNS is effective to suppress NDO in MS patients after PTNS. Although long‐term efficacy of PTNS is known, the findings showed prominent improvements on the clinical and urodynamic outcome, we think that the use of PTNS for DO in MS patients will be promising in clinical practice in the future. Neurourol. Urodynam. 28:964–968, 2009. © 2009 Wiley‐Liss, Inc.
Deterrence, technology, and the sensible distribution of arms control verification resources
Authors: Avenhaus Rudolf , Canty Morton J.
Published: April 2009

For routine inspections in the frame of arms control, we address the determination of a rational basis for the distribution of available verification resources among controlled States. The analysis is performed primarily in the context of the nonproliferation treaty. In the spirit of this treaty, which in its original conception stressed objectivity, we adopt a formal, quantified point of view applying the theory of n‐person noncooperative games. Emphasis is placed on the conditions necessary for fulfillment of the fundamental verification objective of deterring illegal behavior, and reasonable and intuitively understandable conclusions are derived. © 2009 Wiley Periodicals, Inc. Naval Research Logistics 58: 295–303, 2011
Glaucoma: target intraocular pressures and current treatments
Authors: McAllister James
Published: April 2009

Our Drug review of glaucoma management describes the use of target intraocular pressures in directing treatment, and the medical, laser and surgical management options. This is followed by an analysis of prescription data and sources of further information. Copyright © 2009 Wiley Interface Ltd
ARBs: concise guide to properties and recommended use
Authors: Chaplin Steve , McInnes Gordon
Published: April 2009

Steve Chaplin and Professor Gordon McInnes provide an overview of the indications, properties and current recommended place in therapy of the angiotensin‐II receptor antagonists. Copyright © 2009 Wiley Interface Ltd
Recommended use of insulin in type 1 diabetes in children
Authors: Johnston Philip , Flanagan Nuala , Carson Dennis , Bell Patrick
Published: April 2009

Our series Prescribing in children gives practical advice for successful management of childhood problems in general practice. Here, the authors describe the management of type 1 diabetes with insulin and briefly discuss the use of oral hypoglycaemic agents in type 2 diabetes. Copyright © 2009 Wiley Interface Ltd
Surface morphology of zinc oxide nanorods grown by hydrothermal deposition technique
Authors: Hari Parameswar , Spencer Daryl
Published: April 2009

Zinc oxide (ZnO) nanorods grown by hydrothermal techniques are of great interest in photonic and electronic device applications because they offer low cost, low temperature deposition techniques compared to conventional molecular beam vapor deposition and sputtering methods. Our studies of ZnO nanorods grown by hydrothermal technique on indium tin oxide (ITO) coated glass substrates at 90 °C for 9 hours resulted in uniform growth of hexagonally shaped closed nanorod structures. We used scanning electron microscopy (SEM) to map changes in surface morphology of ZnO nanorods grown on various substrates. In this work we investigated the effects of temperature and the choice of conductive substrate on the size and shape of ZnO nanorods grown by hydrothermal growth. In particular, we studied the changes in surface morphology of ZnO nanorods deposited on ITO, ZnO coated glass, Aluminum coated glass, conducting transparent oxide (CTO) glass and mylar substrates. We will present quantitative data on changes in diameter and shape of ZnO nanorods as the growth substrate is varied. We will also discuss the surface morphology of ZnO nanorods grown by hydrothermal techniques at 95 °C on ZnO thin film substrate fabricated by sputter coating of ZnO on glass substrate. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electroluminescence analysis of 1.3‐1.5 μm InAs quantum dot LEDs with (Ga,In)(N,As) capping layers
Authors: Montes M. , Hierro A. , Ulloa J. M. , Guzmán A. , Khalfioui M. Al , Hugues M. , Damilano B. , Massies J.
Published: April 2009

The electroluminescence (EL) of a series of InAs/(Ga,In)(N,As) self‐assembled quantum dot light emitting diodes (QDLEDs) with different capping layer composition is analysed. Room temperature EL close to 1.5 μm is demonstrated using 15% In and 2% N in the capping layer. The origin of the different peaks present in the EL spectra of N‐containing devices has been studied and the higher energy peaks have been attributed to emission from the quantum well constituted by the wetting and the capping layers. The effect of rapid thermal annealing (RTA) on the EL is analysed. It is found that the EL emission energy blue‐shifts after RTA. This blue‐shift is smaller for the N‐containing devices (∼40 meV) than for a InAs/In0.15Ga0.85As reference QDLED (∼85 meV). In addition, the QDLEDs power slope efficiency is also studied at 14 K. It is readily seen that this efficiency decreases by three orders of magnitude with the addition of 2% N to the InGaAs capping layer. Nevertheless, after RTA, this efficiency recovers partially, increasing by two orders of magnitude and reaching values close to those of the N‐free reference QDLEDs. This enhancement can be explained by the reduction of the non‐radiative recombination centre density in the capping layer after RTA, which leads to a higher carrier injection efficiency into the QDs. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical Kerr signals of GaAs/AlAs multilayer cavities for a short pulse
Authors: Morita Ken , Kanbara Toshiyuki , Yano Shinsuke , Kitada Takahiro , Isu Toshirou
Published: April 2009

Optical Kerr signals of GaAs/AlAs multilayer cavities with various quality factor (Q) were measured by an optical pump and probe technique with ultrashort pulses. Although the light intensity is enhanced in the cavities by Q, light power is restricted by the narrower spectrum of the cavity mode than that of the input ultrashort pulse. The measured Kerr signals showed larger dependence on the quality factor than that expected by simple consideration for the field enhancement effect by cavities. It seems that the nonlinear phase shift in the cavity is enhanced by the photon life time in addition to the field enhancement. This indicates that multilayer cavities are useful for enhancement of the optical Kerr signals. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The role of carbon in transport processes during PVT growth of bulk GaN
Authors: Rost H.‐J. , Siche D. , Gogova D. , Albrecht M. , Jacobs K. , Fornari R.
Published: April 2009

Thick GaN layers were deposited by the reaction of gallium with ammonia. The Physical Vapour Transport (PVT) process with NH3 addition is characterized by moderate NH3 flow rates, pressures, and consumption of reactants, by reduced parasitic growth and no NH4Cl formation. Carbon addition to the ammonia results in growth of thicker layers at increased transport rate and in single crystals even at Ga super saturations, which would normally be too high for single crystalline growth. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Narrow‐gap ferromagnetic semiconductors (In,Mn)Sb on GaAs (001): growth and properties
Authors: Tran Lien , Herfort Jens , Bierwagen Oliver , Hatami Fariba , Masselink W. Ted
Published: April 2009

Narrow‐gap (In,Mn)Sb layers, which offer prospects for infrared spin‐photonics, were grown on GaAs (001) substrates using a Riber Compact 21T MBE system and a Veeco valved cracker cell for Sb. Samples consisting 0.4 μm (In,Mn)Sb/GaAs with different Mn content in the range of 1% were examined in this study in respect of their structural, magnetotransport and magnetization properties. It is found that Mn decreases the lattice constant as well as the degree of relaxation of (In,Mn)Sb films. The hole concentration increases with increasing Mn concentration resulting increased acceptor concentration and decreased resistivity.

The magnetoresistance is found to be sensitive to the Mn concentration. The temperature‐dependent resistivity data at lower than 30 K show an increased resistivity with decreasing temperature, suggesting the insulating behavior of the samples. In addition, magnetization measurements reveal distinct hysteresis loops, indicating the ferromagnetic properties. The measured saturation magnetization values of the films are found to be dependent on Mn concentration. The Curie temperature is estimated to be below 50 K. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Biexcitonic photocurrent induced by two‐photon process at a telecommunication band
Authors: Kodera Tetsuo , Suzuki Ayako , Miyazawa Toshiyuki , Takagi Hiroyuki , Kumagai Naoto , Watanabe Katsuyuki , Nakaoka Toshihiro , Arakawa Yasuhiko
Published: April 2009

We report on photocurrent (PC) measurements of biexciton in a single self‐assembled InAs quantum dot (QD) at a telecommunication wavelength of 1.3 μm. We use shadow mask technique on an n‐i Schottky photodiode structure with QDs to excite a single QD resonantly. Coherent pulse excitation is realized in two types of setups utilizing (i) an optical parametric oscillator and (ii) a stable semiconductor laser diode. In both setups we observe the biexcitonic PC peaks induced by a coherent two‐photon process. Especially in the latter setups, the narrower pulse linewidth in energy provides a clearer biexcitonic PC peak because of reduced unwanted excitation. We estimate the binding energy ΔEB of our telecom‐band biexciton to be 0.9 meV from the splitting between excitonic and biexcitonic resonances. The result suggests our telecom‐band exciton‐biexciton system is a good candidate for the building block of fiber‐based controlled‐rotation quantum logic operation. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Heteroepitaxial growth of a rotated AlInSb layer mediated by an InSb bi‐layer on a Si(111) substrate
Authors: Saito Mitsufumi , Mori Masayuki , Ueda Koji , Maezawa Koichi
Published: April 2009

Two‐step growth of an AlInSb film mediated by an InSb bi‐layer on a Si(111) substrate was performed in a molecular beam epitaxy (MBE) chamber. The growth was observed by in situ reflection high energy electron diffraction. After the deposition, the samples were characterized by X‐ray diffraction (XRD). It is confirmed that the grown AlInSb films were rotated by 30° with respect to the Si substrates. The lattice mismatch between the AlInSb and the Si substrate was reduced by the rotation. Using this method, epitaxial AlyIn(1‐y)Sb layers which have the composition ratio y of 0.22‐0.65 can be achieved without thick buffer layers. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
C ‐plane chromia on c ‐plane sapphire
Authors: Tarre A. , Carlotti G. , Gerst A. , Mändar H. , Niilisk A. , Sammelselg V. , Socino G. , Rosental A.
Published: April 2009

Chromium oxide thin films were atomic layer deposited from CrO2Cl2 and CH3OH on α‐Al2O3(0 0 1) (c ‐sapphire) substrates at 420 °C. On the basis of X‐ray reflection evidence, the thickness of the films in a series prepared ranged from 4 to 400 nm. As it was ascertained by reflection high‐energy electron diffraction, the films grew epitaxially. Electron probe microanalysis showed that O/Cr atomic ratio in them was close to 1.5 and that the residual impurities were present in insignificant amounts. The rms roughness of the films measured by atomic‐force microscopy and X‐ray reflection was of the order of 1 nm or less. X‐ray diffraction and Raman scattering data suggested that the films were strained, and that the strain was tensile in the c direction and compressive in the c plane. According to the surface Brillouin scattering measurements, the elastic properties of the films differed only slightly from those for single‐crystal bulk chromia. The films, when surface activated with Pt nanoislands, had a moderate response to CO in air with the transition times in the range of tens of seconds. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Homoepitaxial growth and characterization of ZnO(0001) thin films grown by metalorganic chemical vapor epitaxy
Authors: Ive Tommy , Ben‐Yaacov Tammy , Van de Walle Chris G. , Mishra Umesh K. , Denbaars Steven P. , Speck James S.
Published: April 2009

We study the properties of Zn‐face ZnO(00.1) layers grown on the Zn‐face of high quality ZnO(00.1) single crystal wafers by metalorganic chemical vapour epitaxy. The layers are grown directly on the ZnO substrates without any treatment of the substrate before starting the growth. The growth temperature is varied between 600–1050 °C while the reactor pressure is kept at 50 Torr. Atomic force microscopy reveals monolayer steps with a step length of 170 nm. The root‐mean‐square roughness is 0.1 nm over a 20×20 μm2 area. A two‐dimensional step morphology is only seen for growth temperatures above 950 °C. Layers grown below 950 °C exhibit very rough three dimensional surface morphologies. The full width at half maximum for x‐ray rocking curves is 22 arcsec and 36 arcsec across the (00.2) and the (20.1) reflections, respectively. This is comparable to the rocking curve widths of the as‐received substrates. The peaks of the ZnO epitaxial thin film and the substrate are indistinguishable in reciprocal space maps. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
GaN and digital electronics: A way out of Moore's law?
Authors: Palacios Tomás , Chung Jinwook W. , Saadat Omair , Mieville Frederic
Published: April 2009

After forty years following Moore's law, Si digital electronics is reaching its limits, both in performance and in economic viability. In this paper we describe how nitride semiconductors can be combined with Si electronics to allow electronics to move beyond Moore's law and to enable new functionality. Three different research areas will be discussed: high performance digital circuits, high temperature electronics and heterogeneous integration of nitride and Si electronics. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electroluminescence characterization of AlGaN/GaN HEMTs
Authors: Lossy Richard , Glowacki Arkadiusz , Boit Christian , Würfl Joachim
Published: April 2009

Microscopic electroluminescence (EL) measurements on AlGaN/GaN high‐electron‐mobility transistors are reported. Photon emission is detected from front side and also from the backside of the wafer. Using both detection geometries manufacturing related dependencies can beidentified. Investigation of EL from backside during pinch‐off operation reveals detailed emission pattern that are partially hidden during front side observation. Spectrally resolved photon emission shows different pattern for on‐state and off‐state condition. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electron transport properties in InAs four‐terminal ballistic junctions under weak magnetic fields
Authors: Koyama M. , Fujiwara K. , Amano N. , Maemoto T. , Sasa S. , Inoue M.
Published: April 2009

We report on the electron transport properties based on ballistic electrons under magnetic fields in four‐terminal ballistic junctions fabricated on an InAs/AlGaSb heterostructure. The four‐terminal junction structure is composed of two longitudinal stems with two narrow wires slanted with 30 degree from the perpendicular axis. The electron focusing peak was obtained with the bend resistance measurement. Then it was investigated the nonlinear electron transport property of potential difference between longitudinal stems due to ballistic electrons with applying direct current from narrow wires. Observed nonlinearity showed clear rectification effects which have negative polarity regardless of input voltage polarity. Although this nonlinearity was qualitatively changed due to the Lorentz force under magnetic fields, the degradation of ballistic effects on nonlinear properties were observed when the current increased to higher strength. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multicarrier analysis of magnetotransport data at low and high electric fields
Authors: Murthy O. V. S. N. , Venkataraman V.
Published: April 2009

We present some results on multicarrier analysis of magnetotransport data. Both synthetic as well as data from narrow gap Hg0.8Cd0.2Te samples are used to demonstrate applicability of various algorithms vs. nonlinear least square fitting, Quantitative Mobility Spectrum Analysis (QMSA) and Maximum Entropy Mobility Spectrum Analysis (MEMSA). Comments are made from our experience on these algorithms, and, on the inversion procedure from experimental R/σ‐B to S‐μ specifically with least square fitting as an example. Amongst the conclusions drawn are: (i) Experimentally measured resistivity (Rxx, Rxy) should also be used instead of just the inverted conductivity (σxx, σxy) to fit data to semiclassical expressions for better fits especially at higher B. (ii) High magnetic field is necessary to extract low mobility carrier parameters. (iii) Provided the error in data is not large, better estimates to carrier parameters of remaining carrier species can be obtained at any stage by subtracting highest mobility carrier contribution to σ from the experimental data and fitting with the remaining carriers. (iv)Even in presence of high electric field, an approximate multicarrier expression can be used to guess the carrier mobilities and their variations before solving the full Boltzmann equation. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Differentiation induced byAchyrocline satureioides(Lam) infusion in PC12 cells
Authors: Blasina M. F. , Vaamonde L. , Morquio A. , Echeverry C. , Arredondo F. , Dajas F.
Published: April 2009

Epidemiological studies have shown that flavonoid‐rich plants induce beneficial health effects that are likely beyond their potent antioxidant capacity. Thus, the mechanisms by whichAchyrocline satureioides(AS), a popular South American medicinal plant, protects cells and neurons in culture, are still unclear. In this sense, a recently described trophic capacity for flavonoids, similar to that evoked by growth factors, could be one of the mechanisms involved in AS cellular protection. Since this trophic activity causes differentiation of PC12 cells, the cell differentiation capacity of AS and some of its flavonoids were evaluated. PC12 cells were treated with AS infusion (10 or 20 µg/mL of total polyphenols), quercetin (Q) (12.5 or 25 µm), luteolin (L) (25 µm), Q + L (12.5 µm each one) or nerve growth factor (NGF) for 3 days. Four morphological parameters (percentage of cells with neurites longer than one cell body diameter, percentage of cells with neurites, average number of neurites per cell and percentage of fusiform cells) were explored. The AS infusion showed differentiation capacity on all parameters with similar potency when compared with NGF. Besides, AS was more potent than some of its constituent flavonoids: Q, L or their combination. Copyright © 2009 John Wiley & Sons, Ltd.
Designing a Combinatorial Library by Using Reagent Pharmacophore Fingerprint
Authors: Chen Hongming , Börjesson Ulf , Engkvist Ola , Kogej Thierry , Svensson Mats A. , Blomberg Niklas , Weigelt Dirk , Burrows Jeremy N. , Lange Tim
Published: April 2009

A method is introduced for performing reagent selection for chemical library design based on topological (2D) pharmacophore fingerprints. Optimal reagent selection is achieved by optimizing the Shannon entropy of the 2D pharmacophore distribution for the reagent set. The method, termed ProSAR, is therefore expected to enumerate compounds that could serve as a good starting point for deriving a structure activity relationship (SAR) in combinatorial library design. This methodology is exemplified by library design examples where the active compounds were already known. The results show that most of the pharmacophores on the substituents for the active compounds are covered by the designed library. This strategy is further expanded to include product property profiles for aqueous solubility, hERG risk assessment etc. in the optimization process so that the reagent pharmacophore diversity and the product property profile are optimized simultaneously via a genetic algorithm. This strategy is applied to a two‐dimensional library design example and compared with libraries designed by a diversity based strategy which minimizes the average ensemble Tanimoto similarity. Our results show that by using the PSAR methodology, libraries can be designed with simultaneously good pharmacophore coverage and product property profile
Similarity‐Based Virtual Screening Using Bayesian Inference Network: Enhanced Search Using 2D Fingerprints and Multiple Reference Structures
Authors: Abdo Ammar , Salim Naomie
Published: April 2009

It has been known that different reference structure retrieve different sets of structures. Recent works in similarity searching have suggested that significant improvements in retrieval effectiveness can be achieved by combining results from different reference structures. One of an important characteristic of the Bayesian inference network (BIN) model is that permits the combining of multiple reference structures. In this paper we introduce a formal inference net model to directly combine the contributions of multiple reference structures, and propose a novel approach to the combination of information from various reference structures. The inference net model of similarity, which was designed from this point of view, treats similarity searching as an evidential reasoning process where multiple sources of evidence about target structure are combined to estimate similarity scores. In this paper, we have compared BIN with other similarity searching methods when multiple bioactive reference structures are available. Six different 2D fingerprints were used in combination with data fusion (DF) and nearest neighbor (NN) approaches as search tools and also as descriptors for BIN. Our empirical results show that the BIN consistently outperformed all conventional approaches such as DF and NN, regardless of the fingerprints that were tested. The superiority of BIN over conventional approaches is ascribed to the fact that BIN understands the content of the descriptors of the structures and references and used this understanding to infer the direct relationship between structures and references.