bluuebunny/crossref_metadata_2025 huggingface dataset:
ER suspensions of composite core‐shell microspheres with improved sedimentation stability
Authors: Krzton‐Maziopa A. , Gorkier M. , Plocharski J.
Published: April 2011

Electrorheological (ER) fluids are usually suspensions of solid polarizable particles in nonpolar carrier liquids. Such systems are particularly sensitive to the presence of electric fields, which transform them reversibly into solid‐like bodies. Fast (within milliseconds) and fully reversible reaction of ER fluids to electric field is a subject of great interest because of many possible applications in tunable vibration dampers, clutches, valves, or brakes. A novel type of ER fluids with composite microspheres composed of polymer electrolyte shell with defined shell thickness and inorganic hollow cores has been synthesized and tested in the presence of an electric field. It has been found that suspensions with composite grains possessed more stable ER response with temperature and lower power consumption in comparison to their polymer‐based counterparts. ER effect of the prepared fluids was measured and related to the applied electric field and solid phase properties. It has been also shown that suspensions of composite materials exhibited improved long‐term sedimentation stability in comparison to polymer‐based suspensions due to the formation of weak microstructure which suppressed the sedimentation of solid phase in off‐field state. Copyright © 2011 John Wiley & Sons, Ltd.
An intumescent flame retardant system using β‐cyclodextrin as a carbon source in polylactic acid (PLA)
Authors: Feng Jian‐Xiang , Su Sheng‐Pei , Zhu Jin
Published: April 2011

In this paper, β‐cyclodextrin (CD) was used as effective “green” carbon source to replace pentaerythritol (PER) in an intumescent flame retardant (IFR). The combination of CD with traditional acid resource ammonium polyphosphate (APP) and/or blowing agent melamine (MA) at different weight ratios exhibited outstanding char‐forming ability. It was demonstrated that strong interactions occurred in APP‐CD and MA‐CD systems through thermogravimetric analysis (TGA). Mechanisms of esterification between APP and CD or dehydration between MA and CD were discussed. The APP/MA/CD complexes showed doubled char residue of those calculated based on three single components in nitrogen atmosphere. For instance, the char residue of CD‐APP (at the weight ratio of 1:1) complex was 38 wt% at 700°C, while the calculated char formation was only 19 wt% in N2. After addition of these complexes into polylactic acid (PLA), the flammability of these PLA resins was evaluated by limited oxygen index (LOI) and vertical combustion (UL‐94). The TGA results indicated that the cyclodextrin mixed with APP and MA as a “green” char agent demonstrated outstanding char formation ability for PLA. When the complex contained CD/APP/MA at weight ratio of 1/2/1 and the addition amount of complex in PLA was 20 wt%, the PLA composites showed LOI values of 34.2 and passed UL 94 V0 rating, and the char residue of the PLA composite was 17.4 wt% at 700°C while only 7.4 wt% was achieved for the calculated composition. Copyright © 2011 John Wiley & Sons, Ltd.
Preparation and properties of polycarbonate/polyhedral oligomeric silsesquioxanes (POSS) hybrid composites
Authors: Cai Hualun , Zhang Xiuju , Xu Kai , Liu Huan , Su Jiangxun , Liu Xin , Fu Zien , Guo Ying , Chen Mingcai
Published: April 2011

Octaphenylsilsesquioxane (PH‐POSS) and octa(γ‐methacryloxypropyl)silsesquioxane (MA‐POSS) were successfully synthesized by hydrolytic condensation of phenyltrichlorosilane and γ‐methacryloxypropyltrimethoxysilane, and characterized by Fourier transform infrared (FT‐IR), 1H and 29Si nuclear magnetic resonance (NMR), and matrix‐assisted laser desorption/ionization‐time of flight (MALDI‐TOF) mass spectrum. Morphology, degradation behavior, thermal, and mechanical properties of hybrid composites were studied by transmission electron microscopy (TEM), polarized optical microscopy (POM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), surface contact angle (SCA), tensile, and impact testing. Domains of PH‐POSS and MA‐POSS dispersed in the matrix with a wide size distribution in a range of 0.1–0.5 µm, while PH‐POSS exhibited a preferential dispersion. Because of the possible homopolymerization of MA‐POSS during the melt blending, the glass transition temperature of polycarbonate (PC)/MA‐POSS composites remained nearly unchanged with respect to PC/PH‐POSS composites that showed a depression of Tg due to the plasticization effect. It is interesting to note that the incorporation of POSS retarded the degradation rates of PC composites and thus significantly improved the thermal stabilities. SiO fractions left during POSS degradations were a key factor governing the formation of a gel network layer on the exterior surface. This layer possessed more compact structures, higher thermal stabilities, and some thermal insulation. In addition, percentage residues at 700°C (C700) significantly increased from 10.8% to 15.8–22.1% in air. Fracture stress of two composites showed a slight improvement, and the impact strength of them decreased monotonically with the increase of POSS loading. Copyright © 2011 John Wiley & Sons, Ltd.
Intravenous infusion of Hb‐vesicles (artificial oxygen carriers) after repetitive blood exchange with a series of plasma expanders (water‐soluble biopolymers) in a rat model
Authors: Sakai Hiromi , Miyagawa Norihito , Horinouchi Hirohisa , Takeoka Shinji , Takaori Masuhiko , Tsuchida Eishun , Kobayashi Koichi
Published: April 2011

Hemoglobin‐vesicles (HbV) are artificial oxygen carriers developed for use as a transfusion alternative. The extremely high concentration of the HbV suspension (solutes, ca. 16 g/dl; volume fraction, ca. 40 vol%) provides a sufficient oxygen carrying capacity to maintain oxygen metabolism. A suspension of HbV has no colloid osmotic pressure (COP). Consequently, a combination of a plasma expander is necessary for a massive dose of HbV. Clinically available plasma expanders include hydroxyethyl starch (HES), modified gelatin (MFG), or recombinant human serum albumin (rHSA). Our previous studies confirmed that these water‐soluble biopolymers interact with HbV to induce flocculation of HbV reversibly by depletion interaction, especially with MFG and high molecular weight HES. It remains unknown whether such flocculate formation in blood might affect animal's hemodynamics. Using a rat model, we tested infusion of a series of plasma expander to maintain the blood volume (level of blood exchange led to 60%) at repeated hemorrhages and the subsequent infusion of HbV (20 ml/kg, 36% of blood volume). All rats survived for 4 hr after the infusion of HbV; hemodynamic and respiratory functions were preserved, indicating that the flocculation does not induce capillary embolism. Blood exchange with rHSA and subsequent infusion of HbV showed more stable systemic parameters because of the longer retention of rHSA in blood than other plasma substitutes, indicating that rHSA is suitable for combination with HbV in this experimental model. Copyright © 2011 John Wiley & Sons, Ltd.
Identification of abrogated pathways in fallopian tube epithelium from BRCA1 mutation carriers
Authors: George Sophia HL , Greenaway James , Milea Anca , Clary Victoria , Shaw Sanjeev , Sharma Monika , Virtanen Carl , Shaw Patricia A
Published: April 2011

The discovery of occult invasive and intra‐epithelial tubal carcinomas in BRCA1 mutation carriers undergoing prophylactic surgery has implicated the fallopian tube epithelium as the source of serous cancer. However, little is known of the early molecular events of serous oncogenesis, or why cancers in BRCA1 mutation carriers are found preferentially in tissues which are responsive to reproductive hormones. We hypothesize that molecular alterations present in morphologically normal tubal epithelium from BRCA1 heterozygotes reflect the earliest events in serous carcinogenesis and may be markers of increased cancer risk as well as targets for risk reduction. Genetic profiling of microdissected tubal epithelium from histologically normal BRCA1 mutation carriers and controls was performed. We sought to define a signature which differentiated BRCA1 mutant tubal epithelium from women with low risk of developing ovarian cancer. Molecular differences between the follicular and luteal phases were prominent and, by using filtering techniques and a two‐way ANOVA without a False Discovery Rate correction, we identified 440 probe sets with a more than two‐fold change in gene expression related to BRCA1 mutation status. Using gene ontology and known associations to cancer pathways, we selected five genes for further analysis by qPCR and immunohistochemistry, and were able to demonstrate statistically significant differentiation of BRCA1 and control cases in an independent set of cases. The altered expression profiles in histologically normal tubal epithelium from BRCA1 heterozygotes suggest that these cells may respond differently to microenvironmental stresses. Copyright © 2011 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Neuroblastoma: A 20‐year experience in a UK regional centre
Authors: Salim Adeline , Mullassery Dhanya , Pizer Barry , McDowell Heather P. , Losty Paul D.
Published: April 2011

Purpose

The role of surgery in the management of neuroblastoma yields conflicting reports. We report a 20‐year experience from a UK centre in the context of evolving cancer therapies for neuroblastoma.

Methods

Hospital records of 91 neuroblastoma patients from 1985 to 2005 were studied. Patient demographics, data from operating notes and tumour biology (MYCN status) where available were analysed.

Results

Surgery consisted of primary resection or delayed operation following tumour biopsy/chemotherapy. Overall survival was 100% for stage 1(n = 3), 90% for stage 2 (n = 10), 46% for stage 3 (n = 13), 13% for stage 4 (n = 55) and 56% for stage 4S disease (n = 9). During the eras 1985–1994 versus 1995–2005, survival for stage 3 lesions was 25% and 80% (P = 0.04) with marginal increase in survival observed in stage 4 disease (12% vs. 22%, P = 0.083). Delayed tumour resection was not performed in 20 (36%) stage 4 patients due to progressive disease. Complete tumour resection was achieved in 62% of stage 3–4 patients during 1995–2005 compared to 38% in 1985–1994. The extent of surgical resection (complete vs. partial) showed no significant differences in overall survival or relapse rates. Postoperative morbidity occurred in 15.7% of cases emphasising technical challenges in resection of neuroblastoma. No child with MYCN amplification survived versus 59% survival in non‐amplified cases (P = 0.012).

Conclusions

While complete tumour resection may be desirable in advanced neuroblastoma (stage 3–4) these findings suggest that the radicality of operation is not significantly associated with better overall survival/relapse. Improving outcomes in the 1995–2005 era for patients with stage 3–4 tumours complements the introduction of new high dose‐intensive chemotherapy regimens and other adjuvant therapies for this enigmatic disease. Pediatr Blood Cancer 2011; 57: 1254–1260. © 2011 Wiley Periodicals, Inc.
Simultaneous Identification of Multiple Celangulins from the Root Bark of Celastrus angulatus Using High‐performance Liquid Chromatography–Diode Array Detector–Electrospray Ionisation–Tandem Mass Spectrometry
Authors: Wei Shaopeng , Gao Jinming , Wu Wenjun , Ji Zhiqin , Zhang Jiwen
Published: April 2011

Introduction

Celangulins are a small family of β‐dihydroagarofuran sesquiterpenoids endowed with diverse polyoxygenated polyol esters and various biological properties. Since our research focuses on celangulins, the development of rapid and sensitive online analytical methods to analyse and characterise them is of great significance.

Objective

To develop an HPLC‐DAD‐ESI‐MS/MS method capable of simple and rapid analysis of celangulins in crude extract of root bark of C. angulatus extracts.

Methodology

High‐performance liquid chromatography coupled with a diode array detector and electrospray ionisation tandem mass spectrometry was established for the efficient and rapid identification of the celangulins. Chromatographic separations of celangulins were performed on a Hypersil Gold C18 reverse‐phase column by gradient elution with acetonitrile–water as mobile phase at a flow‐rate 0.2 mL/min.

Results

ESI/MS/MS analysis of sodium adduct ion ([M + Na]+) of each celangulin shows that all the celangulins produced very similar fragmentation profiles, and that the characteristic fragments at m/z 245, m/z 229 and m/z 231 were defined as the diagnostic ions for celangulins. Simultaneously, 46 components in the extracts of this plant were separated, and 36 of them were characterised as celangulins by online ESI/MS/MS and by comparing their retention times, UV and MS spectra with those of authentic compounds.

Conclusion

HPLC‐DAD‐ESI‐MS/MS was demonstrated to be a powerful tool for the characterisation of minor celangulins in complex samples. Copyright © 2011 John Wiley & Sons, Ltd.
Calix[4]arene‐tetranitrone as crosslinker in dental composite materials
Authors: Tabatabai Monir , Garska Bernd , Moszner Norbert , Utterodt Andreas , Ritter Helmut
Published: April 2011

The synthesis of a functionalized calix[4]arene bearing 1,3‐dipolaric nitrone groups (5) has been carried out. The reaction of N‐methylhydroxylamine or N‐propylhydroxylamine with the carbonyl group of 5,11,7,23‐tetraformyl‐25,26,27,28‐tetraalkoxycalix[4]arene leads to calix[4]arenes bearing a nitrone function at each of the four para‐positions. Via 1,3‐dipolar cyclo‐addition of acrylic acid methyl ester with the nitrone functions of 5, subsequently an upper rim‐substituted tetraisoxalidinecalix[4]arene is quantitatively synthesized. Further, the minimization of shrinkage of a dental filling depending on the amount of calix[4]arene‐tetranitrone is discussed. Copyright © 2011 Society of Chemical Industry
Metallocene ethylene‐co‐(5,7‐dimethylocta‐1, 6‐diene) copolymers crosslinked using electron beam irradiation: a tunable alternative
Authors: Cerrada María L , Benavente Rosario , Fernández‐García Marta , Pérez Ernesto , Campos João M , Ribeiro Rosário
Published: April 2011

Ethylene‐co‐(5,7‐dimethylocta‐1,6‐diene) copolymers with various 5,7‐dimethylocta‐1,6‐diene contents incorporate double bonds in the lateral chains that facilitate the development of crosslinkings in the resulting polymeric material after electron beam irradiation. As an effect of such irradiation, crystallization is delayed but crystallinity remains practically constant after melting and further cooling of irradiated specimens. Crystallinity, crystallite thickness and gel content are key parameters in the mechanical performance of these copolymers. Consequently, the controlled incorporation of non‐conjugated dienes into the polyethylene structure appears as an alternative strategy for tuning the mechanical response in crosslinked polyolefins. Moreover, the resulting materials exhibit good thermal stability. Copyright © 2011 Society of Chemical Industry
Imprinted β‐cyclodextrin polymers using naringin as template
Authors: Ma Xiuling , Chen Zhen , Chen Riyao , Zheng Xi , Chen Xiao , Lan Ruifang
Published: April 2011

The objective of this study was to identify a kind of molecular imprinting polymer (MIP) which was suitable for recognizing naringin (NG) in aqueous medium. Based on two crosslinkers (hexamethylene diisocyanate and epichlorohydrin) and two polymerization methods (solution polymerization and emulsion polymerization), four non‐covalent naringin‐β‐cyclodextrine (NG‐β‐CD) imprinted polymers were prepared by using β‐CD as a functional monomer and NG as a template molecule. The binding property and selectivity were evaluated by equilibrium binding experiments. These demonstrated that all the sites in the MIPs show good selective binding ability for NG from naringin dihydrochalcone, a structurally similar molecule. Of the four MIPs, rod‐like 3# MIP which was prepared by emulsion polymerization using hexamethylene diisocyanate as crosslinker exhibited the highest selectivity, its imprinting factor α being 1.53. Scatchard analysis of 3# MIP suggests that there are two classes of binding sites during the MIP's recognition of NG. Additionally, the 3# MIP could be used at least five times without any loss in sorption capacity. Copyright © 2011 Society of Chemical Industry
A simulation study towards a new concept for realization of thin film triple junction solar cells based on group IV elements
Authors: Feser C. , Lacombe J. , v. Maydell K. , Agert C.
Published: April 2011

In this paper, the theoretical efficiency of multi‐junction solar cells based on group IV elements has been investigated. The effects of different absorbing layer numbers, different band gap combinations, and temperature changes have been reviewed for multi‐spectral solar cells. Several simulations were done to identify the ideal band gap combination for triple‐junction solar cells. Based on these results and under consideration of actual material parameters, a new promising triple‐junction solar cell concept with a‐Si:H/µc‐Si:H/ and µc‐Ge:H has been found for developing high efficiency thin film solar cells. Additionally, advanced simulations were performed in order to evaluate the feasibility of this new concept. The photocurrent, the external quantum efficiency, and the layer thicknesses were simulated and evaluated. All parameters deliver promising results for a new triple‐junction solar cell concept with an intermediate reflector between the middle‐ and bottom structure. Copyright © 2011 John Wiley & Sons, Ltd.
Proteins in leaked amniotic fluid as biomarkers diagnostic for prelabor rupture of membranes
Authors: Wang Tao , Zhou Rong , Zhang Lin , Wang Yanyun , Song Chang ping , Lin Wei , Niu Xiaoyu , Lin Yong , Hu Huaizhong
Published: April 2011

Purpose: Early diagnosis of prelabor rupture of membranes (PROM) is essential to protect mother and fetus from intra‐uterus infection and preterm birth. A simple and rapid bedside test would help clinicians confirm the diagnosis for early treatment.

Experimental design: A protein array was used to screen cervical–vaginal fluid (CVF) and amniotic fluid (AF) samples collected from normal and PROM pregnant women. Enzyme‐linked immunosorbent assay was used to quantify two novel and potentially useful analytes, soluble intercellular adhesion molecule‐1 (sICAM‐1) and Axl receptor tyrosine kinase (Axl).

Results: The mean concentration of sICAM‐1 and Axl was 85 and 482 times higher separately in 30 healthy AF samples than in 110 CVF samples of normal pregnancies. Comparing 110 CVF samples of PROM/Preterm PROM with 110 CVF samples of normal pregnancies, the diagnostic value for PROM was demonstrated by their high sensitivity and specificity (96.4 and 92.7%, respectively, for sICAM‐1, and 92.4 and 90.4%, respectively, for Axl).

Conclusions and clinical relevance: The results indicate that sICAM‐1 and Axl in AF leaked to vagina are sensitive and specific biomarkers for the diagnosis of PROM. Furthermore, sICAM‐1 or Axl can be developed into a rapid strip test for bedside use.
Overview on string phenomenology
Authors: Uranga A.M.
Published: April 2011

I provide an introduction and update on the status of string theory models of particle physics, and in particular focus on recent developments flux compactifications and non‐perturbative D‐brane instanton effects.
Extremal black hole flows and duality
Authors: Ceresole A.
Published: April 2011

Extremal black holes in extended supergravity theories can be obtained as solutions of first order flow equations even when they are not supersymmetric, provided one identifies a suitable superpotential W appearing in the effective potential, and driving the evolution of the scalar fields. W also gives the black hole horizon entropy and the ADM mass. We describe how classical U‐duality allows to determine W in many models and to classify both regular and singular solutions.
On the spectral properties of multi‐branes, M2 and M5 branes
Authors: Garcia del Moral M.P. , Restuccia A.
Published: April 2011

In this note we summarize some of the properties found in [1–3]. We characterize spectral properties of the quantum mechanical hamiltonian of theories with fermionic degrees of freedom beyond semiclassical approximation. We obtain a general class of bosonic polynomial potentials for which the Schröedinger operator has a discrete spectrum. This class includes all the scalar potentials in membrane, 5‐brane, p‐branes, multiple M2 branes, BLG and ABJM theories. We also give a sufficient condition for discreteness of the spectrum for supersymmmetric and non supersymmetric theories with a fermionic contribution. We characterize then the spectral properties of different theories: the BMN matrix model, the supermembrane with central charges and a bound state of N D2 with m D0. We show that, while the first two models have a purely discrete spectrum with finite multiplicity, the latter has a continuous spectrum starting from a constant given in terms of the monopole charge.
High energy cosmic rays from decaying dark matter
Authors: Ibarra A.
Published: April 2011

We discuss the implications of the excess in the total electron plus positron flux and the positron fraction reported by the Fermi and PAMELA collaborations, respectively, for the scenario of decaying dark matter. We also discuss the constraints on this scenario from measurements of other cosmic ray species and the predictions for the diffuse gamma ray flux and the neutrino flux. In particular, we expect a sizable dipole‐like anisotropy in the diffuse gamma‐ray flux which may be observed by the Fermi‐LAT in the near future.
Narrow resonances at the early LHC
Authors: Torre R.
Published: April 2011

We discuss the possibility to observe new resonances at the early LHC using a phenomenological approach. We show predictions for the production of a scalar in the gg‐channel and an heavy quark in the qg‐channel and we compare them with the recent results of the ATLAS and CMS experiments in the di‐jet channel, setting upper limits on the relevant couplings. We finally discuss the importance of the final states containing at least one photon making sensitivity predictions for the corresponding couplings.
The termiticidal activity of Sextonia rubra (Mez) van der Werff (Lauraceae) extract and its active constituent rubrynolide
Authors: Rodrigues Alice MS , Amusant Nadine , Beauchêne Jacques , Eparvier Véronique , Leménager Nicolas , Baudassé Christine , Espindola Laila S , Stien Didier
Published: April 2011

BACKGROUND: Termites are degradation agents that inflict severe damage on wood. Some long‐lasting Amazonian trees can resist these insects by producing toxic secondary metabolites. These metabolites could potentially replace synthetic termiticidal products which are becoming more restricted to use.

RESULTS: Sextonia rubra is resistant to termite‐induced degradation. It has been demonstrated that this species naturally produces an ethyl‐acetate‐soluble termiticidal metabolite, rubrynolide, to protect its wood. Assays in the presence of tropical and invasive termites established that both rubrynolide and crude ethyl acetate extract from S. rubra wood can be used as a treatment for the protection of sensitive woods against termites.

CONCLUSION: Rubrynolide and S. rubra extract are promising candidates for the replacement of synthetic termiticides. Copyright © 2011 Society of Chemical Industry
Development and evaluation of a new method for sampling and monitoring the symphylid population in pineapple
Authors: Soler Alain , Gaude Jean‐Marie , Marie‐Alphonsine Paul‐Alex , Vinatier Fabrice , Dole Bernard , Govindin Jean‐Claude , Fournier Patrick , Queneherve Patrick
Published: April 2011

BACKGROUND: Symphylids (Hanseniella sp.) are polyphagous soilborne parasites. Today, symphylid populations on pineapple are monitored by observing root symptoms and the presence of symphylids at the bottom of basal leaves. The authors developed a reliable method with a bait and trap device to monitor symphylid populations in pineapple or fallow crops. The spatial distribution of the symphylid populations was evaluated using the variance/mean ratios and spatial analyses based on Moran's and Geary's indices. The method has been tested to monitor symphylid populations at different developmental stages of pineapple.

RESULTS: Adding potato baits to the soil samples increased the trapping efficiency of symphylids when compared with ‘soil only’ and ‘bait only’ methods. The handling of the samples is also facilitated by the new device. Results showed that the vertical distribution of symphylids may be uniform deeply inside the soil profile under pineapple, up to 50 cm. Results showed that symphylid populations are highly aggregated, showing a spot area about 4–6 m wide for their development.

CONCLUSION: The new method allows better and easier evaluation of symphylid populations. It may be very useful in the evaluation of new IPM methods to control symphylids under pineapple. Copyright © 2011 Society of Chemical Industry
Monitoring of spirodiclofen susceptibility in field populations of European red mites, Panonychus ulmi (Koch) (Acari: Tetranychidae), and the cross‐resistance pattern of a laboratory‐selected strain
Authors: Kramer Tina , Nauen Ralf
Published: April 2011

BACKGROUND: Phytophagous mites such as the European red mite, Panonychus ulmi (Koch), are serious pests in European fruit tree orchards, and a number of acaricides are frequently used to control them. Spirodiclofen (Envidor®) has been a commonly used acaricide for several years. In the present study, European field populations collected in 2009 and 2010 were checked for their susceptibility to spirodiclofen by using discriminating dose and full dose response bioassays.

RESULTS: In 2009 and 2010, a total of 63 field populations (including winter eggs) of European red mites were collected in different European countries, and in several populations from south‐western Germany a shifting in susceptibility against spirodiclofen was observed. Full dose response bioassays on different developmental stages of field‐collected strains suggested an age‐dependent expression of resistance because eggs remain fully susceptible to spirodiclofen. Artificial selection with spirodiclofen of one of the field strains resulted in resistance ratios of > 7000. Synergism studies suggest a possible role of cytochrome‐P450‐dependent monooxygenases in spirodiclofen detoxification. Most of the other acaricides from different chemical classes displayed no or low cross‐resistance in a spirodiclofen‐selected strain.

CONCLUSION: In order to preserve spirodiclofen as an important tool in spider mite resistance management, the efficacy situation should be continuously monitored, and it is suggested that spirodiclofen be alternated with acaricides coming from different mode‐of‐action classes. An observed age‐specific expression of resistance revealed full susceptibility of eggs, so targeting spirodiclofen particularly against eggs is likely to reduce the selection pressures imposed on other life stages. Copyright © 2011 Society of Chemical Industry
Full optical phonon states and their dispersive spectra of a wurtzite GaN/AlGaN superlattice: Quantum size effect
Authors: Zhang L.
Published: April 2011

The polar optical phonon states of four types of phonon modes including the interface optical (IO) modes, the propagating (PR) modes, the quasi‐confined (QC) phonon modes in well‐layer material (QCw), and the QC phonon modes in barrier‐layer material (QCB) in a wurtzite GaN/AlxGa1–xN superlattice (SLs) are investigated within the dielectric continuum model framework. The analytical phonon states of the four types of modes and their dispersive equations in the wurtzite GaN/AlxGa1–xN SL structures are obtained. Numerical calculations on the dispersive spectra of phonon modes and the quantum size effect are performed for a wurtzite GaN/Al0.15Ga0.85N SL. Results reveal that dispersive curves of phonon modes in SLs form a series of frequency bands. The behaviors of QCwmodes reducing to PR and IO modes are observed clearly. With the increase of well‐layer GaN widthd1of the SLs, the dispersion of the QCBmodes become weaker and weaker, and their frequency bands become narrower and narrower. But the PR, IO, and the QCwphonon modes become more dispersive, and the frequency bands of these modes become wider and wider asd1increases. The present theoretical scheme and numerical results are quite useful for analyzing the dispersive spectra of full phonon modes and their polaronic effect in wurtzite GaN/AlGaN SL structures.
Curie temperatures of the concentrated and diluted Kondo‐lattice model as a possible candidate to describe magnetic semiconductors and metals
Authors: Stier M. , Nolting W.
Published: April 2011

We present a theory to model carrier mediated ferromagnetism in concentrated or diluted local moment systems. The electronic subsystem of the Kondo lattice model (KLM) is described by a combined equation of motion (EOM)/coherent potential approximation (CPA) method. Doing this we can calculate the free energy of the system and its minimum according to the magnetization of the local moments. Thus, also the Curie temperature can be determined and its dependence on important model parameters. We get qualitative agreement with the Curie temperatures' experimental values of Ga1–xMnxAs for a proper hole density.
X‐ray detectors based on Fe doped GaN photoconductors
Authors: Fu Kai , Yu Guohao , Yao Changsheng , Wang Guo , Lu Min , Zhang Guoguang
Published: April 2011

X‐ray detectors based on Fe doped GaN photoconductors have been fabricated. The dark current Id and photocurrent Ip as a function of bias have been investigated and a large Ip/Id ratio of 180 at 200 V has been obtained in spite of optical quenching. The physical mechanism of the transient per‐ formance of the photoconductor has been studied through fitting the experimental data. The functions of photocurrent versus acceleration voltage and current of the X‐ray source have been measured and discussed. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Local spatial biclustering and prediction of urban juvenile delinquency and recidivism
Authors: Izenman Alan J. , Harris Philip W. , Mennis Jeremy , Jupin Joseph , Obradovic Zoran
Published: April 2011

Using a novel database, ProDES, developed by the Crime and Justice Research Center at Temple University, this article investigates the relationship between spatial characteristics and juvenile delinquency and recidivism—the proportion of delinquents who commit crimes following completion of a court‐ordered program—in Philadelphia, PA. ProDES was originally a case‐based sample, where the cases were adjudicated in family court, 1994–2004. For our analysis, we focused attention on studying 6768 juvenile males from the data set. To address the difficult issue of nonstationarity in the data, we considered various two‐way clustering algorithms to group the juveniles into ‘types’ by way of the many variables that described the juveniles. Following different modeling scenarios, we applied the plaid biclustering algorithm in which a sequence of subsets (‘layers’) of both juveniles and variables are extracted from the data one layer at a time, but where overlapping layers are allowed. This type of ‘biclustering’ is a new way of studying juvenile‐offense data. We show that the juveniles within each layer can be viewed as spatially clustered. The layers were determined as descriptive tools to aid in identifying subsets of the data that could be useful in policy making. Statistical relationships of the variables and juveniles within each layer are then studied using neural network models. Results indicate that the methods of this paper are more successful in predicting juvenile recidivism in urban environments when different crimes are modeled as separate data sets rather than being pooled together as a single data set. © 2011 Wiley Periodicals, Inc. Statistical Analysis and Data Mining 2011
An extension of the single threshold design for monitoring efficacy and safety in phase II clinical trials
Authors: Brutti P. , Gubbiotti S. , Sambucini V.
Published: April 2011

Tan and Machin (biStat. Med. 2002; 21:1991–2012) introduce a Bayesian two‐stage design for phase II clinical trials where the binary endpoint of interest is treatment efficacy. In this paper we propose an extension of their design to incorporate safety considerations. At each stage we define the treatment successful and deserving of further study if the total number of adverse events is sufficiently small and the number of responders who simultaneously do not experience any toxicity is sufficiently large. Therefore, our criterion is based on the joint posterior probability that the true overall toxicity rate and the true efficacy‐and‐safety rate are, respectively, smaller and larger than conveniently pre‐specified target values. The optimal two‐stage sample sizes are determined specifying a minimum threshold for the above‐mentioned posterior probability, computed under the assumption that favorable outcomes have occurred. Besides describing the proposed design, we suggest how to construct informative prior scenarios and we also apply the reference algorithm to derive a non‐informative prior distribution. Finally, some numerical results are provided and a real data application is illustrated. Copyright © 2011 John Wiley & Sons, Ltd.
On the clinical meaningfulness of a treatment's effect on a time‐to‐event variable
Authors: Snapinn Steven , Jiang Qi
Published: April 2011

The standard analysis of a time‐to‐event variable often involves the calculation of a hazard ratio based on a survival model such as Cox regression; however, many people consider such relative measures of effect to be poor expressions of clinical meaningfulness. Two absolute measures of effect are often used to assess clinical meaningfulness: (1) many disease areas frequently use the absolute difference in event rates (or its inverse, the number‐needed‐to‐treat) and (2) oncology frequently uses the difference between the median survival times in the two groups. While both of these measures appear reasonable, they directly contradict each other. This paper describes the basic mathematics leading to the two measures and shows examples. The contradiction described here raises questions about the concept of clinical meaningfulness. Copyright © 2011 John Wiley & Sons, Ltd.
Virus‐Based Nanoparticles with Inorganic Cargo: What Does the Future Hold?
Authors: Bronstein Lyudmila M.
Published: April 2011

An analysis of the accumulated knowledge on virus‐based nanoparticles (VNPs) consisting of virus protein capsids and inorganic cargo, such as nanoparticles (NPs), nanowires, and thin layers, is presented. Virus capsids (VCs) can serve either as templates or nanoreactors when inorganic materials are formed outside or inside VCs. The third possibility is when inorganic NPs nucleate the formation of VCs. The structural and mechanistic studies of VNP formation are paving the way to a better understating of virus structure and behavior, and these facilitate promising applications of VNPs in biomedical and materials research.
Covalent Immobilization of Aggregation‐Induced Emission Luminogens in Silica Nanoparticles Through Click Reaction
Authors: Mahtab Faisal , Lam Jacky W. Y. , Yu Yong , Liu Jianzhao , Yuan Wangzhang , Lu Ping , Tang Ben Zhong
Published: April 2011

Fluorescent silica nanoparticles (FSNPs) with efficient light emission, colloidal stability, and size tunability are fabricated by one‐pot, two‐step Stöber and reverse microemulsion techniques. Tetraphenylethene (TPE)‐ and silole‐functionalized siloxanes are facilely synthesized by click reactions and their sol–gel reactions followed by reactions with tetraethoxysilane generate FSNPs with core–shell structures. The FSNPs are uniformly sized with smooth surfaces, and show high surface charges and hence excellent colloidal stability. UV irradiation of ethanol solutions of the FSNPs gives strong blue and green light at 474 and 486 nm in high fluorescence quantum yields, thanks to the novel aggregation‐induced emission attributes of the TPE and silole aggregates in the hybrid nanoparticles. The FSNPs are benign to living cells and function as fluorescent visualizers for intracellular imaging of HeLa cells.
Investigation of Plasmon Resonances in Metal Films with Nanohole Arrays for Biosensing Applications
Authors: Sannomiya Takumi , Scholder Olivier , Jefimovs Konstantins , Hafner Christian , Dahlin Andreas B.
Published: April 2011

Biosensing with nanoholes is one of the most promising applications of nanoplasmonic devices. The sensor properties, however, are complex due to coupled resonances through propagating and localized surface plasmons. This Full Paper demonstrates experimental and simulation studies on different plasmonic hole systems, namely various patterns of circular holes in gold films. In contrast to most previous work, here, the challenging situation of optically thin films is considered. The refractive‐index‐sensing properties, such as sensitive locations in the nanostructure and sensitive spectral features, are investigated. The multiple multipole program provides the complete field distribution in the nanostructure for different wavelengths. It is shown that the spectral feature most sensitive to refractive‐index changes is the extinction minimum, rather than the maximum. The results are consistent with theory for perfect electrical conductors. The spectral response is investigated for molecular adsorption at different positions inside or outside a hole. Furthermore, the optical properties of nanohole arrays with long‐range and short‐range order are compared and found to demonstrate remarkable similarities. Our results help to predict the resonance wavelengths of nanoholes with arbitrary patterns, including short‐range order. The results presented here are highly important since they extend and challenge several aspects of the current understanding of plasmon resonances in nanohole arrays. These theoretical models, simulation results, and experimental data together help provide the understanding necessary for the development of efficient biomolecular analysis tools based on metallic nanoholes.
Cellular Uptake, Intracellular Trafficking, and Cytotoxicity of Nanomaterials
Authors: Zhao Feng , Zhao Ying , Liu Ying , Chang Xueling , Chen Chunying , Zhao Yuliang
Published: April 2011

The interactions of nanoparticles with the soft surfaces of biological systems like cells play key roles in executing their biomedical functions and in toxicity. The discovery or design of new biomedical functions, or the prediction of the toxicological consequences of nanoparticles in vivo, first require knowledge of the interplay processes of the nanoparticles with the target cells. This article focusses on the cellular uptake, location and translocation, and any biological consequences, such as cytotoxicity, of the most widely studied and used nanoparticles, such as carbon‐based nanoparticles, metallic nanoparticles, and quantum dots. The relevance of the size and shape, composition, charge, and surface chemistry of the nanoparticles in cells is considered. The intracellular uptake pathways of the nanoparticles and the cellular responses, with potential signaling pathways activated by nanoparticle interactions, are also discussed.
Nano‐C60: A Novel, Effective, Fluorescent Sensing Platform for Biomolecular Detection
Authors: Li Hailong , Zhang Yingwei , Luo Yonglan , Sun Xuping
Published: April 2011

Water‐soluble nano‐C60 can serve as a novel, effective, fluorescent sensing platform for biomolecular detection with high sensitivity and selectivity. In this paper, fluorescent detection of DNA and thrombin via nano‐C60 is demonstrated for the first time. The principle of the assay lies in the fact that the adsorption of the fluorescently labeled single‐stranded DNA (ssDNA) probe by nano‐C60 leads to substantial fluorescence quenching. In the presence of a target, the biomolecular mutual interaction suppresses this quenching, signaling the existence of the target. This sensing system rivals graphene oxide but is superior to other carbon‐structure‐based systems. The present method can also achieve multiplex DNA detection and withstand the interference from human blood serum.
PPM compression without escapes
Authors: Fenwick P. M.
Published: April 2011

A significant cost in PPM data compression (and often the major cost) is the provision and efficient coding of escapes while building contexts. This paper presents some recent, preliminary, work on a new technique for eliminating escapes in PPM compression, using bit‐wise compression with binary contexts. It shows that PPM without escapes can achieve averages of 2.5 bits per character on the Calgary Corpus and 2.2 bpc on the Canterbury Corpus, both values comparing well with accepted good compressors. Copyright © 2011 John Wiley & Sons, Ltd.
Agile methods for open source safety‐critical software
Authors: Gary Kevin , Enquobahrie Andinet , Ibanez Luis , Cheng Patrick , Yaniv Ziv , Cleary Kevin , Kokoori Shylaja , Muffih Benjamin , Heidenreich John
Published: April 2011

The introduction of software technology in a life‐dependent environment requires the development team to execute a process that ensures a high level of software reliability and correctness. Despite their popularity, agile methods are generally assumed to be inappropriate as a process family in these environments due to their lack of emphasis on documentation, traceability, and other formal techniques. Agile methods, notably Scrum, favor empirical process control, or small constant adjustments in a tight feedback loop. This paper challenges the assumption that agile methods are inappropriate for safety‐critical software development. Agile methods are flexible enough to encourage the right amount of ceremony; therefore if safety‐critical systems require greater emphasis on activities, such as formal specification and requirements management, then an agile process will include these as necessary activities. Furthermore, agile methods focus more on continuous process management and code‐level quality than classic software engineering process models. We present our experiences on the image‐guided surgical toolkit (IGSTK) project as a backdrop. IGSTK is an open source software project employing agile practices since 2004. We started with the assumption that a lighter process is better, focused on evolving code, and only adding process elements as the need arose. IGSTK has been adopted by teaching hospitals and research labs, and used for clinical trials. Agile methods have matured since the academic community suggested almost a decade ago that they were not suitable for safety‐critical systems; we present our experiences as a case study for renewing the discussion. Copyright © 2011 John Wiley & Sons, Ltd.
An analytical approach to free vibration analysis of multi‐outrigger–belt truss‐reinforced tall buildings
Authors: Malekinejad Mohsen , Rahgozar Reza
Published: April 2011

This paper deals with a new and simple mathematical model that may be used to determine natural frequencies and mode shapes of a multistory building that consists of a framed tube, a shear core and multi‐outrigger–belt trusses. The effect of outrigger–belt truss and shear core on a framed tube was modeled as a concentrated moment placed at outrigger–belt truss location, which acted in opposite direction of the rotation created by lateral loads. The analysis is based on a continuum approach, in which a tall building structure may be replaced by an idealized cantilevered beam to model the building's structural characteristics. Energy method and Hamilton's principle have been used to develop the governing equations. After applying separation of variables method to time and space variables, the resulting eigensystem was solved to obtain the building's natural modes and frequencies of vibration. A computer program has been developed in MATLAB (Mathworks Inc., CA, USA) environment, and a numerical example has been solved to demonstrate the accuracy of this method. Results obtained from the proposed mathematical model give a good understanding of a structure's dynamic characteristics. The method is simple to use yet reasonably accurate and hence suitable for quick evaluations during preliminary design stages. Copyright © 2011 John Wiley & Sons, Ltd.
Longitudinal trends in fetoplacental biochemical markers, uterine artery pulsatility index and maternal blood pressure during the first trimester of pregnancy
Authors: Wortelboer E. J. , Koster M. P. H. , Kuc S. , Eijkemans M. J. C. , Bilardo C. M. , Schielen P. C. J. I. , Visser G. H. A.
Published: April 2011

Objective

To assess trends in levels of biochemical markers, uterine artery (UtA) pulsatility index (PI) and maternal blood pressure changes over time and study their relationships in uncomplicated first‐trimester pregnancies.

Methods

The study population comprised 86 women with singleton pregnancies. In each woman, a blood sample was collected at 6–7, 8–9, 10–11 and 12–13 weeks' gestation. At the same visit blood pressure was measured and ultrasound examination was performed to measure the crown–rump length and Doppler flow velocity waveform patterns of both UtAs. Serum concentrations of pregnancy‐associated plasma protein‐A (PAPP‐A), free β‐human chorionic gonadotropin (β‐hCG), A disintegrin and metalloprotease domain‐containing protein‐12 (ADAM‐12), placental protein‐13 (PP‐13) and placental growth factor (PlGF) levels were measured in thawed specimens using an automated time‐resolved fluorescence assay. Summary curves were created to describe normal ranges and trends over time. The data were analyzed with a linear mixed model with the log‐transformed marker values as dependent variables. This allowed for flexible modeling of patterns over time.

Results

Sixty‐eight pregnancies had an uneventful outcome, with the birth of an appropriate‐for‐gestational‐age (AGA) infant. In these pregnancies serum PAPP‐A, ADAM‐12, PP‐13 and PlGF levels increased with gestational age. The UtA‐PI decreased and the mean arterial blood pressure remained constant. There were no significant correlations between maternal age, birth‐weight percentile, gender and blood pressure and any of the biochemical markers. The serum markers were highly correlated with each other except for β‐hCG. A negative correlation was found between most biomarkers and UtA‐PI, especially from 10 weeks onwards. Serum concentrations of ADAM‐12 and PP‐13 were lower in a small‐for‐gestational‐age (SGA) subgroup born at term (n = 6), the former statistically significantly (P = 0.031), the latter non‐significantly (P = 0.054), whereas UtA‐PI was significantly higher (P = 0.02). Biomarker concentrations in 12 women delivering a large‐for‐gestational age infant did not differ from those delivering AGA neonates.

Conclusion

There is a relationship between biochemical markers of early placentation and downstream resistance to flow in the UtAs in low‐risk uncomplicated pregnancies, indicating differences in placentation. In a small series of SGA infants born at term we could demonstrate differences as compared to normal pregnancies, with potential value for screening. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.
Prenatal diagnosis of a pulmonary arteriovenous malformation
Authors: Akler G. , Tamir A. , Malinger G. , Yagel S.
Published: April 2011

Pulmonary arteriovenous malformations (PAVMs) are caused by abnormal communications between pulmonary arteries and pulmonary veins. They are most often congenital, and may occur as isolated lesions or part of complex congenital syndromes. We describe a case of PAVM in a 16‐week‐old fetus. To the best of our knowledge this is the first case to be described in the literature of diagnosis, at such an early gestational age, of PAVM with the shunt found between the main pulmonary artery and pulmonary vein. Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.