bluuebunny/crossref_metadata_2025 huggingface dataset:
Theoretical Study on the Mechanism of Ni‐Catalyzed Alkyl–Alkyl Suzuki Cross‐Coupling
Authors: Li Zhe , Jiang Yuan‐Ye , Fu Yao
Published: February 2012

Ni‐catalyzed cross‐coupling of unactivated secondary alkyl halides with alkylboranes provides an efficient way to construct alkyl–alkyl bonds. The mechanism of this reaction with the Ni/L1 (L1=trans‐N,N′‐dimethyl‐1,2‐cyclohexanediamine) system was examined for the first time by using theoretical calculations. The feasible mechanism was found to involve a NiI–NiIII catalytic cycle with three main steps: transmetalation of [NiI(L1)X] (X=Cl, Br) with 9‐borabicyclo[3.3.1]nonane (9‐BBN)R1 to produce [NiI(L1)(R1)], oxidative addition of R2X with [NiI(L1)(R1)] to produce [NiIII(L1)(R1)(R2)X] through a radical pathway, and CC reductive elimination to generate the product and [NiI(L1)X]. The transmetalation step is rate‐determining for both primary and secondary alkyl bromides. KOiBu decreases the activation barrier of the transmetalation step by forming a potassium alkyl boronate salt with alkyl borane. Tertiary alkyl halides are not reactive because the activation barrier of reductive elimination is too high (+34.7 kcal mol−1). On the other hand, the cross‐coupling of alkyl chlorides can be catalyzed by Ni/L2 (L2=trans‐N,N′‐dimethyl‐1,2‐diphenylethane‐1,2‐diamine) because the activation barrier of transmetalation with L2 is lower than that with L1. Importantly, the Ni0–NiII catalytic cycle is not favored in the present systems because reductive elimination from both singlet and triplet [NiII(L1)(R1)(R2)] is very difficult.
Generating Orally Active Galanin Analogues with Analgesic Activities
Authors: Robertson Charles R. , Pruess Timothy H. , Grussendorf Erin , White H. Steve , Bulaj Grzegorz
Published: February 2012

The endogenous neuropeptide galanin has anticonvulsant and analgesic properties mediated by galanin receptors expressed in the central and peripheral nervous systems. Our previous work showed that by combining truncation of the galanin peptide with N‐ and C‐terminal modifications afforded analogues that suppress seizures or pain upon intraperitoneal (i.p.) administration. To generate orally active galanin analogues, the previously reported lead compound Gal‐B2 (NAX 5055) was redesigned by 1) central truncation, (2) introduction of D‐amino acids, and 3) addition of backbone spacers. Analogue D‐Gal(7‐Ahp)‐B2, containing 7‐aminoheptanoic acid as a backbone spacer and an oligo‐D‐lysine motif at the C terminus, exhibits anticonvulsant and analgesic activity post‐i.p. administration. Oral administration of D‐Gal(7‐Ahp)‐B2 demonstrates analgesic activity with decreases in both acute and inflammatory pain in the mouse formalin model of pain at doses as low as 8 mg kg−1.
Computational modelling of cardiac electrophysiology: explanation of the variability of results from different numerical solvers
Authors: Pathmanathan P. , Bernabeu M.O. , Niederer S.A. , Gavaghan D.J. , Kay D.
Published: February 2012

A recent verification study compared 11 large‐scale cardiac electrophysiology solvers on an unambiguously defined common problem. An unexpected amount of variation was observed between the codes, including significant error in conduction velocity in the majority of the codes at certain spatial resolutions. In particular, the results of the six finite element codes varied considerably despite each using the same order of interpolation. In this present study, we compare various algorithms for cardiac electrophysiological simulation, which allows us to fully explain the differences between the solvers. We identify the use of mass lumping as the fundamental cause of the largest variations, specifically the combination of the commonly used techniques of mass lumping and operator splitting, which results in a slightly different form of mass lumping to that supported by theory and leads to increased numerical error. Other variations are explained through the manner in which the ionic current is interpolated. We also investigate the effect of different forms of mass lumping in various types of simulation. Copyright © 2012 John Wiley & Sons, Ltd.
A model of axonal transport drug delivery: effects of diffusivity
Authors: Kuznetsov A.V.
Published: February 2012

This paper investigates the effects of diffusivity on retrograde dynein‐driven transport of pharmaceutical agent complexes (PACs) in axons. The model is designed with two goals in mind: (1) to capture results on axonal transport drug delivery reported in recent experimental research by Filler et al. (Filler AG, Whiteside GT, Bacon M, Frederickson M, Howe FA, Rabinowitz MD, Sokoloff AJ, Deacon TW, Abell C, Munglani R, Griffiths JR, Bell BA, Lever AML. Tri‐partite complex for axonal transport drug delivery achieves pharmacological effect. BMC Neuroscience 2010; 11: 8) and (2) to produce analytically tractable equations. It is shown that the inclusion of a diffusion process in the model produces equations that can still be solved by Laplace transform, although the last step of the solution, finding the inverse Laplace transform, has to be accomplished numerically, thus leading to a hybrid analytical and numerical solution technique. The effects of diffusivity and the kinetic rates describing PAC transition between the dynein‐driven and accumulated states on transport of PACs toward the neuron soma are investigated. Copyright © 2012 John Wiley & Sons, Ltd.
Azafullerene C59N–Phthalocyanine Dyad: Synthesis, Characterisation and Photoinduced Electron Transfer
Authors: Rotas Georgios , Ranta Jenni , Efimov Alexander , Niemi Marja , Lemmetyinen Helge , Tkachenko Nikolai , Tagmatarchis Nikos
Published: February 2012

The synthesis of a new azafullerene C59N–phthalocyanine (Pc) dyad is described. The key step for the synthesis of the C59N–Pc dyad was the formation of the C59N‐based carboxylic acid, which was smoothly condensed with hydroxy‐modified Pc. The structure of the C59N–Pc dyad was verified by 1H and 13C NMR spectroscopy, IR spectroscopy, UV/Vis spectroscopy and MS measurements. The photophysical and electrochemical properties of the C59N–Pc dyad were investigated in both polar and non‐polar solvents by steady state and time‐resolved photoluminescence and absorption spectroscopy, as well as by cyclic voltammetry. Different relaxation pathways for the photoexcited C59N–Pc dyad, as a result of changing the solvent polarity, were found, thus giving rise to energy‐transfer phenomena in non‐polar toluene and charge‐transfer processes in polar benzonitrile. Finally, the detailed quenching mechanisms were evaluated and compared with that of a C60–Pc dyad, which revealed that the different excited‐state energies and reduction potentials of the two fullerene spheres (i.e. C59N vs. C60) strongly diverged in the deactivation pathways of the excited states of the corresponding phthalocyanine dyads.
Shear Modulus of a Coulomb Crystal of Ions: Effects of Ion Motion and Electron Background Polarization
Authors: Baiko D. A.
Published: February 2012

Shear modulus of a body‐centered cubic Coulomb crystal of ions is calculated by thermodynamic perturbation theory taking into account ion motion. Classic and quantum regimes of ion motion are considered. The calculations in the classic range of high temperatures agree well with previous Monte Carlo simulations. In this case, the shear modulus is given by a sum of a positive contribution due to the static lattice and a negative ∝ T contribution due to the ion motion. In the quantum regime of low temperatures, the contribution to the shear modulus due to the ion motion saturates at a negative constant value, determined by zero‐point ion vibrations.

The correction to the static lattice shear modulus due to the polarization of the electron background is also calculated. The background polarization is described by a dielectric function in the linear response formalism. We compare two dielectric functions (simple Thomas‐Fermi and more realistic Jancovici) and find dependence of the correction to the shear modulus on the ion charge number and the electron degree of relativity.

The numerical results are approximated by simple analytical formulas. They can be applied to matter in white dwarf cores and neutron star crusts for precise modeling of oscillations of these astrophysical objects (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamic Screening in Solar and Stellar Nuclear Reactions
Authors: Däppen W. , Mussack K.
Published: February 2012

In the hot, dense plasma of solar and stellar interiors, Coulomb potentials are screened, resulting in increased nuclear reaction rates. Although Salpeter's approximation for static screening is widely accepted and used in stellar modeling, the question of screening in nuclear reactions was revisited in the 1990s. In particular the issue of dynamic effects was raised by Shaviv and Shaviv, who applied the techniques of molecular dynamics to the conditions in the Sun's core in order to numerically determine the effect of screening. By directly calculating the motion of ions and electrons due to Coulomb interactions, the simulations are used to compute the effect of screening without the mean‐field assumption inherent in Salpeter's approximation. In the last few years, the USC group has first reproduced Shaviv and Shaviv's numerical analysis of the screening energy, showing an effect of dynamic screening. When the consequence for the reaction‐rate was computed, a rather surprising resulted, which is contrary to that from static screening theory. Our calculations showed that dynamic screening does not significantly change the reaction rate from that of the bare Coulomb potential. If this can be independently confirmed, then the effects of dynamic screening are highly relevant and should be included in stellar nuclear reaction rates (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Improvement of Wave Packet Molecular Dynamics Using Packet Splitting
Authors: Morozov I. V. , Valuev I. A.
Published: February 2012

The method of Wave Packet Molecular Dynamics Method (WPMD) is a promising replacement of the classical molecular dynamics for the simulations of many‐electron systems including nonideal plasmas. In this contribution we report on a packet splitting technique where an electron is represented by multiple Gaussians, with mixing coefficients playing the role of additional dynamic variables. It provides larger flexibility and better accuracy than the original WPMD with a single Gaussian per electron. As a test case we consider ionization of hydrogen atom in a short laser pulse, where the split packets provide a basis for quantum branching (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Development of an electrospray LC‐MS/MS method for quantification of Δ9‐tetrahydrocannabinol and its main metabolite in oral fluid
Authors: Bylda Caroline , Leinenbach Andreas , Thiele Roland , Kobold Uwe , Volmer Dietrich A.
Published: February 2012

A fast and sensitive reference method for quantification of Δ9‐tetrahydrocannabinol (THC) and its main metabolite 11‐nor‐9‐carboxy‐Δ9‐tetrahydrocannabinol (THCCOOH) in oral fluid is described in this study. Samples were collected using an oral specimen collection device, followed by solid‐phase extraction and liquid chromatography‐tandem mass spectrometry analysis. Chromatographic separation of the analytes was achieved by gradient elution on a reversed‐phase column with subsequent detection by electrospray triple quadrupole mass spectrometry in positive ionization multiple reaction monitoring mode. Quantification was performed by means of deuterated analogues of the analytes as internal standards. Total run time of the assay was 12 min. The method allowed sensitive quantification of both analytes at a limit of quantification of 0.2 ng/ml. This sensitivity is essential for analysis of samples collected with the Intercept Oral Fluid Collection device (OraSure) and an assay for simultaneous quantification of THC and THCCOOH in saliva has not yet been described. The calibration curves for THC and THCCOOH were linear in the range between 0.25 and 8 ng/ml (r2 > 0.99). Ion suppression effects from endogenous or exogenous interferences were investigated using selected model substances (albumin, ascorbic acid, bilirubin, hemoglobin, breath spray, cigarette, chewing gum, chewing tobacco, candy, tooth whitening, and Tums antacid). These substances were chosen because of the high probability of their presence in the collected samples. None of the 11 endogenous model interferences altered the accuracy of analysis, demonstrating good robustness of the method with respect to interferences in common hygiene products, medicine, tobacco and naturally occurring endogenous substances. Copyright © 2012 John Wiley & Sons, Ltd.
Organophosphorus hydrolase as an in vivo catalytic nerve agent bioscavenger
Authors: Wales Melinda E. , Reeves Tony E.
Published: February 2012

The use of proteins as a treatment for organophosphorus intoxication has been investigated since A. R. Main demonstrated protective efficacy against parathion with an exogenously administered arylesterase in the late 1950s. His experiments spurred over 60 years of research and progress in the development of enzymes as potential bioscavengers of nerve agents and pesticides. Efforts have been made to broaden the specificity of enzymes to make a universal scavenger that would protect against multiple compounds, and an understanding of the differential isomer toxicity of these compounds has provided the impetus for rational and random mutagenic approaches in the stereospecific design of enzymes. As improved candidate enzymes are continually developed, our understanding of the contributions of the catalytic parameters (kcat, KM and catalytic efficiency) to efficacy expands. In addition to the scavenging properties of the proteins, another important aspect of development is the pharmacokinetic profile of the drug product. Immunogenicity, absorption, distribution and elimination contribute significantly to the level of protection afforded by the protein. A review of the development of organophosphorus hydrolase (OPH) for use as in vivo catalytic bioscavengers is presented here. Copyright © 2012 John Wiley & Sons, Ltd.
Fluorine in psychedelic phenethylamines
Authors: Trachsel Daniel
Published: February 2012

The so‐called psychedelic phenethylamines represent a class of drugs with a large range of psychoactive properties in humans, ranging from naturally occurring mescaline to amphetamine analogues and homologues. The interest in many of these compounds, occasionally referred to as designer‐drugs, is widely dispersed across popular culture and political and scientific communities. In recent decades, fluorine has become a powerful and important tool in medicinal chemistry. In addition, fluorine‐containing compounds and medicines can be found in numerous commercially successful pharmaceuticals that have gained a market share of some 5–15%. One might anticipate this trend to increase in the future. As far as fluorinated phenethylamines are concerned, much less is known about their chemistry and pharmacology. This paper provides an overview regarding the biological properties of over 60 fluorinated phenethylamines and discusses both historical and recent chemistry‐related developments. It was shown that the introduction of fluorine into the phenethylamine nucleus can impact greatly on psychoactivity of these compounds, ranging from marked loss to enhancement and prolongation of effects. For example, in contrast to the psychoactive escaline (70), it was observed that its fluoroescaline (76) counterpart was almost devoid of psychoactive effects. Difluoroescaline (77), on the other hand, retained, and trifluoroescaline (78) showed increased human potency of escaline (70). Difluoromescaline (72) and trifluoromescaline (73) increasingly surpassed human potency and duration of mescaline (22) effects. Copyright © 2012 John Wiley & Sons, Ltd.
An evaluation of the DRI‐ETG EIA method for the determination of ethyl glucuronide concentrations in clinical and post‐mortem urine
Authors: Turfus Sophie C. , Vo Tu , Niehaus Nadia , Gerostamoulos Dimitri , Beyer Jochen
Published: February 2012

A commercial enzyme immunoassay for the qualitative and semi‐quantitative measurement of ethyl glucuronide (EtG) in urine was evaluated. Post‐mortem (n=800), and clinical urine (n=200) samples were assayed using a Hitachi 902 analyzer. The determined concentrations were compared with those obtained using a previously published liquid chromatography‐tandem mass spectrometry (LC‐MS/MS) method for the quantification of EtG and ethyl sulfate.

Using a cut‐off of 0.5 µg/ml and LC‐MS/MS limit of reporting of 0.1 µg/ml, there was a sensitivity of 60.8% and a specificity of 100% for clinical samples. For post‐mortem samples, sensitivity and specificity were 82.4% and 97.1%, respectively. When reducing the cut‐off to 0.1 µg/ml, the sensitivity and specificity were 83.3% and 100% for clinical samples whereas for post‐mortem samples the sensitivity and specificity were 90.3 % and 88.3 %, respectively. The best trade‐offs between sensitivity and specificity for LC‐MS/MS limits of reporting of 0.5 and 0.1 µg/ml were achieved when using immunoassay cut‐offs of 0.3 and 0.092 µg/ml, respectively. There was good correlation between quantitative results obtained by both methods but analysis of samples by LC‐MS/MS gave higher concentrations than by enzyme immunoassay (EIA), with a statistically significant proportional bias (P<0.0001, Deming regression) for both sample types. The immunoassay is reliable for the qualitative and semi‐quantitative presumptive detection of ethyl glucuronide in urine. Copyright © 2012 John Wiley & Sons, Ltd.
A critical review of reports of endogenous psychedelic N, N‐dimethyltryptamines in humans: 1955–2010
Authors: Barker Steven A. , McIlhenny Ethan H. , Strassman Rick
Published: February 2012

Three indole alkaloids that possess differing degrees of psychotropic/psychedelic activity have been reported as endogenous substances in humans; N,N‐dimethyltryptamine (DMT), 5‐hydroxy‐DMT (bufotenine, HDMT), and 5‐methoxy‐DMT (MDMT). We have undertaken a critical review of 69 published studies reporting the detection or detection and quantitation of these compounds in human body fluids. In reviewing this literature, we address the methods applied and the criteria used in the determination of the presence of DMT, MDMT, and HDMT. The review provides a historical perspective of the research conducted from 1955 to 2010, summarizing the findings for the individual compounds in blood, urine, and/or cerebrospinal fluid. A critique of the data is offered that addresses the strengths and weaknesses of the methods and approaches to date. The review also discusses the shortcomings of the existing data in light of more recent findings and how these may be overcome. Suggestions for the future directions of endogenous psychedelics research are offered. Copyright © 2012 John Wiley & Sons, Ltd.
Distribution patterns of groundwater‐dependent vegetation species diversity and their relationship to groundwater attributes in northwestern China
Authors: Zhu JunTao , Yu JingJie , Wang Ping , Yu Qiang , Eamus Derek
Published: February 2012

The study of the patterns of plant species diversity and the factors influencing these patterns is the basis of ecology and is also fundamental to conservation biology. Groundwater‐dependent vegetation (GDV) must have access to groundwater to maintain their growth and function, and this is especially common in arid and semi‐arid regions, including north‐western China. In this paper, plant species diversity and groundwater attributes (composition and depth) were investigated in 31 plots in the Ejina Delta in north‐western China to determine whether groundwater attributes influenced patterns species diversity in GDV. Detrended canonical correspondence analyses and generalised additive models were performed to analyse the data. A total of 29 plant species were recorded in the 31 plots; perennial herbs with deep roots had an advantage over all other groups, and GDV species diversity was primarily affected by groundwater depth (GWD), salinity (SAL) and total dissolved solids (TDS), HCO3−, Ca2+, pH, and SO42−. The herb layer species diversity and total species diversity reached their maximum in similar, moderate environmental conditions. The diversity of the tree species was influenced by SAL and TDS and was maximal at large values of GWD and low values of SAL and TDS. The diversity of shrub species was affected by Ca2+ and Mg2+ and was maximal low GWD and high SAL and TDS. Patrick's and Shannon–Wiener's index of the total community diversity presented a bimodal pattern along gradients of GWD and SAL, whilst Simpson's and Pielou's index showed a partially unimodal pattern. On the basis of field investigation and the analysis of field data, we concluded that the perfect combination of GWD and SAL for GDV species diversity is 2 m and 1·8 g l−1, respectively. The appropriate combination range is 2–5 m and 1·8–4·2 g l−1, and the critical combination for the damaged GDV species diversity is 5 m and 4·2 g l−1. Copyright © 2012 John Wiley & Sons, Ltd.
Self‐Assembly of 1D, 2D, and 3D Lanthanide‐Metal Coordination Polymers Based on a 2‐(Pyridin‐4‐yl)‐4,5‐imidazoledicarboxylate Linker: Synthesis, Structures, and Luminescence
Authors: Sun Lin , Li Gui‐Zhu , Xu Mei‐Hua , Li Xiao‐Jian , Li Jian‐Rong , Deng Hong
Published: February 2012

Three series of novel lanthanide‐based 1D, 2D, and 3D metallic coordination frameworks involving the 2‐pyridin‐4‐yl‐4,5‐imidazoledicarboxylic acid (H3PIDC) ligand have been characterized by elemental analysis, infrared spectroscopy, thermogravimetric analysis, and single‐crystal X‐ray diffraction. The compound [Tb(PIDC)(H2O)4]·H3PIDC·4H2O (1) upon slow evaporation at room temperature gave a 1D coordination chain framework constructed of [Tb2O2] dimers bridged through the carboxylate groups of PIDC3– ligands; a 3D supramolecular structure is generated through hydrogen bonding and π–π interactions. The second kind of lanthanide‐based coordination framework, namely [Ln(H2PIDC)(ox)H2O]·3H2O [Ln = Sm (2), Gd (3), Dy (4), and Ho (5), ox = oxalic acid], synthesized under hydrothermal conditions, self‐assemble through Ln2[H2PIDC]2 building blocks and bridging oxalate ligands to give a 2D coordination layer structure. The adjacent layers stack to form a 3D supramolecular framework through weak interactions such as hydrogen bonding and π–π interactions. The third series of lanthanide‐based coordination compounds with chemical formula [Ln(HPIDC)(ox)1/2H2O]·3H2O [Ln = Gd (6), Dy (7), Tb (8) and Ho (9)] were also synthesized by hydrothermal reaction. These isostructural compounds contain an infinite –Ln–O–C–O–Ln– zigzag chain, which connect to each other through the oxygen atoms of the HPIDC2– ligands to form a wave‐like layer. The layers are bridged by oxalate ligands to generate a 3D coordination framework.
Complexation of Palladium(II) with Unsaturated Dithioethers – A Systematic Development of Highly Selective Ligands for Solvent Extraction
Authors: Traeger Juliane , Klamroth Tillmann , Kelling Alexandra , Lubahn Susanne , Cleve Ernst , Mickler Wulfhard , Heydenreich Matthias , Müller Holger , Holdt Hans‐Jürgen
Published: February 2012

There is a demand for new and robust PdIIextractants due to growing recycling rates. Chelating dithioethers are promising substances for solvent extraction as they form stable square‐planar complexes with PdII. We have modified unsaturated dithioethers, which are known to coordinate PdII, and adapted them to the requirements of industrial practice. The ligands are analogues of 1,2‐dithioethene with varying electron‐withdrawing backbones and polar end‐groups. The crystal structures of several ligands and their palladium complexes were determined as well as their electro‐ and photochemical properties, complex stability and behaviour in solution. Solvent extraction experiments showed the superiority of some of our ligands over conventionally used extractants in terms of their very fast reaction rates. With highly selective 1,2‐bis(2‐methoxyethylthio)benzene (4) it is possible to extract PdIIfrom a highly acidic medium in the presence of other base and palladium‐group metals.
Substructure shake table test method using a controlled mass: formulation and numerical simulation
Authors: Nakata Narutoshi , Stehman Matthew
Published: February 2012

This study proposes a new substructure shake table test method that allows for experimental investigation of the lower portion of structures while the upper part is numerically analyzed. Compatibility conditions are derived to ensure that the dynamic characteristics of the substructured system are equivalent to the reference entire structure. This method utilizes controlled masses to incorporate interface forces from the computational substructure to the experimental substructure. A feasible implementation procedure for the interface force compatibility is developed using a series of conversions and signal processing. For validation of the capabilities and limitations of the proposed substructure method, numerical simulations are performed using detailed models including dynamics of the controlled mass systems. Results from the numerical simulations showed that the proposed substructure method produced comparable results to the reference entire simulations. The average error between top floor displacements produced by substructured and entire responses for earthquake inputs was 7.1%. Numerical studies showed that the substructure method has potential to serve as an alternative to shaking table tests of entire structures. Copyright © 2012 John Wiley & Sons, Ltd.
Remote detection of interfered downlinks in wireless cellular systems
Authors: Reyes‐Guerrero J. C. , Murillo‐Fuentes J. J. , Olmos P. M.
Published: February 2012

This work provides a novel technological solution to jamming in wireless systems, particularly to remotely detect interfered communications in a cellular network. The new system is focused on the detection of a failure in a link between a base station and a fixed wireless terminal located in a residential or business area. It has an important impact in security systems based on wireless terminals to transmit an alarm to a central station. In these systems, non‐authorised people can prevent the transmission of the alarm by using a short‐range jammer. The main advantage of this proposal is that it is non‐intrusive; that is, no modification is needed in the base station, and no protocol modification is performed in the terminal. The detection is implemented in an external unit developed on a software‐defined radio platform. The novel system proposed is valid for any cellular system and operator. In this work, we focus on its implementation in the GSM/GPRS system to illustrate its benefits and outline the method for Universal Mobile Telecommunications System. We describe the results of some experiments where the system successfully detects the presence of a short‐range jammer in a real scenario. Copyright © 2012 John Wiley & Sons, Ltd.
Study on flashover in a single chamber lined with combustible materials
Authors: Chen Aiping , Zhou Liang , Lu Shizheng
Published: February 2012

With the theories of fire dynamics and relevant parameters of combustible lining materials, a predicted model of hot gas layer temperature during pre‐flashover stage of enclosure fires was established, and the effects of lining materials on the likelihood of flashover were theoretically analyzed. By using common commercial lining materials, such as wall papers, foam plastics, wood‐based panels, and fabric‐upholstered wall panel, the phenomenon of flashover was reproduced in a small‐scale firebox of 1/4 sizes of ISO 9705 test chamber. By comparing the theoretical results with experimental data, the equation predicting the hot gas layer of quasi‐steady enclosure fires was gained; an indicator IFO to reflect overall the hazards of flashover and to classify flashover fires was proposed, and its application was initially studied. The study results can be helpful to explain further and overall the effects of lining materials on enclosure fires and can be used to guide the prevention of flashover by choosing appropriate interior decoration materials. Copyright © 2012 John Wiley & Sons, Ltd.
Proper cerebellar development requires expression of β1‐integrin in Bergmann glia, but not in granule neurons
Authors: Frick Alexandra , Grammel Daniel , Schmidt Felix , Pöschl Julia , Priller Markus , Pagella Pierfrancesco , von Bueren André O. , Peraud Aurelia , Tonn Jörg‐Christian , Herms Jochen , Rutkowski Stefan , Kretzschmar Hans A. , Schüller Ulrich
Published: February 2012

β1‐class integrins play essential roles both in developmental biology as well as in cancer. Particularly, a Nestin‐driven deletion of β1‐integrin receptors results in severe abnormalities of brain development including a laminar disorganization of cerebellar granule neurons. However, since Nestin is expressed in all kinds of neural precursors, these data do not allow conclusions to be drawn about the role of β1‐integrins in distinct neuronal and glial cell types. By generating conditional knockout mice using granule cell‐specific Math1‐promoter sequences, we show here that the expression of β1‐integrins in granule neurons is dispensable for the development of the cerebellum. Also, deletion of β1‐integrin from tumors that arise in a mouse model of granule cell precursor‐derived medulloblastoma did not result in a significant survival benefit. Last, expression levels of β1‐integrin in human medulloblastoma samples did not predict patient's outcome. However, a β1‐integrin knockout using hGFAP‐promoter sequences led to cerebellar hypoplasia, inappropriate positioning of Bergmann glia cells in the molecular layer, undirected outgrowth of radial glia fibers, and granule cell ectopia. We therefore conclude that β1‐integrin expression in cerebellar granule neurons is not essential during normal development or medulloblastoma formation. In fact, it is the expression of β1‐integrin in glia that is crucial for the proper development of the cerebellar cortex. © 2012 Wiley Periodicals, Inc.
Enhancer of zeste homolog 2 epigenetically silences multiple tumor suppressor microRNAs to promote liver cancer metastasis
Authors: Au Sandy Leung-Kuen , Wong Carmen Chak-Lui , Lee Joyce Man-Fong , Fan Dorothy Ngo-Yin , Tsang Felice Hoching , Ng Irene Oi-Lin , Wong Chun-Ming
Published: February 2012

Epigenetic alterations and microRNA (miRNA) deregulation are common in hepatocellular carcinoma (HCC). The histone H3 lysine 27 (H3K27) tri-methylating enzyme, enhancer of zeste homolog 2 (EZH2) mediates epigenetic silencing of gene expression and is frequently up-regulated in human cancers. In this study we aimed to delineate the implications of EZH2 up-regulation in miRNA deregulation and HCC metastasis. Expressions of a total of 90 epigenetic regulators were first determined in 38 pairs of primary HCCs and their corresponding nontumorous livers. We identified EZH2 and its associated polycomb repressive complex 2 (PRC2) as one of the most significantly deregulated epigenetic regulators in primary HCC samples. Up-regulation of EZH2 was next confirmed in 69.5% (41/59) of primary HCCs. Clinicopathologically, EZH2 up-regulation was associated with HCC progression and multiple HCC metastatic features, including venous invasion (

P

= 0.043), direct liver invasion (

P

= 0.014), and absence of tumor encapsulation (

P

= 0.043). We further demonstrated that knockdown of EZH2 in HCC cell lines reduced the global levels of tri-methylated H3K27, and suppressed HCC motility

in vitro

and pulmonary metastasis in a nude mouse model. By interrogating the miRNA expression profile in EZH2-knockdown cell lines and primary HCC samples, we identified a subset of miRNA that was epigenetically suppressed by EZH2 in human HCC. These included well-characterized tumor-suppressor miRNAs, such as miR-139-5p, miR-125b, miR-101, let-7c, and miR-200b. Pathway enrichment analysis revealed a common regulatory role of these EZH2-silenced miRNAs in modulating cell motility and metastasis-related pathways. Our findings suggest that EZH2 exerts its prometastatic function by way of epigenetic silencing of multiple tumor suppressor miRNAs.

Conclusion

: Our study demonstrated that EZH2 epigenetically silenced multiple miRNAs that negatively regulate HCC metastasis. (HEPATOLOGY 2012)
Persistence of hepatitis A vaccine induced seropositivity in infants and young children by maternal antibody status: 10-year follow-up
Authors: Sharapov Umid M. , Bulkow Lisa R. , Negus Susan E. , Spradling Philip R. , Homan Chriss , Drobeniuc Jan , Bruce Michael , Kamili Saleem , Hu Dale J. , McMahon Brian J.
Published: February 2012

Persistence of seropositivity conferred by hepatitis A vaccine administered to children <2 years of age is unknown and passively transferred maternal antibodies to hepatitis A virus (maternal anti-HAV) may lower the infant's immune response to the vaccine. One hundred ninety-seven infants and young children were randomized into three groups to receive a two-dose hepatitis A vaccine: group 1 at 6 and 12 months, group 2 at 12 and 18 months, and group 3 at 15 and 21 months of age. Within each group, infants were randomized by maternal anti-HAV status. Anti-HAV levels were measured at 1 and 6 months and at 3, 5, 7, and 10 years after the second dose of hepatitis A vaccination. Children in all groups had evidence of seroprotection (>10 mIU/mL) at 1 month after the second dose. At 10 years, all children retained seroprotective anti-HAV levels except for only 7% and 11% of children in group 1 born to anti-HAV–negative and anti-HAV–positive mothers, respectively, and 4% of group 3 children born to anti-HAV–negative mothers. At 10 years, children born to anti-HAV–negative mothers in group 3 had the highest geometric mean concentration (GMC) (97 mIU/mL; 95% confidence interval, 71-133 mIU/mL) and children born to anti-HAV–positive mothers in group 1 had the lowest GMC (29 mIU/mL; 95% confidence interval, 20-40 mIU/mL). Anti-HAV levels through 10 years of age correlated with initial peak anti-HAV levels (tested at 1 month after the second dose).

Conclusion

: The seropositivity induced by hepatitis A vaccine given to children <2 years of age persists for at least 10 years regardless of presence of maternal anti-HAV. (HEPATOLOGY 2012)
Differential effects of substrate modulus on human vascular endothelial, smooth muscle, and fibroblastic cells
Authors: Robinson Karyn G. , Nie Ting , Baldwin Aaron D. , Yang Elaine C. , Kiick Kristi L. , Akins Robert E.
Published: February 2012

Regenerative medicine approaches offer attractive alternatives to standard vascular reconstruction; however, the biomaterials to be used must have optimal biochemical and mechanical properties. To evaluate the effects of biomaterial properties on vascular cells, heparinized poly(ethylene glycol) (PEG)‐based hydrogels of three different moduli, 13.7, 5.2, and 0.3 kPa, containing fibronectin and growth factor were utilized to support the growth of three human vascular cell types. The cell types exhibited differences in attachment, proliferation, and gene expression profiles associated with the hydrogel modulus. Human vascular smooth muscle cells demonstrated preferential attachment on the highest‐modulus hydrogel, adventitial fibroblasts demonstrated preferential growth on the highest‐modulus hydrogel, and human umbilical vein endothelial cells demonstrated preferential growth on the lowest‐modulus hydrogel investigated. Our studies suggest that the growth of multiple vascular cell types can be supported by PEG hydrogels and that different populations can be controlled by altering the mechanical properties of biomaterials. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 2012.
Promoted healing of femoral defects with in situ grown fibrous composites of hydroxyapatite and poly(DL‐lactide)
Authors: Zou Bin , Chen Xian , Zhi Wei , Liu Yaowen , Cui Wenguo , Hu Shuchun , Li Xiaohong
Published: February 2012

Although, electrospun composite fibers have shown promise in enhancing growth, differentiation, and mineralization of osteoblasts in vitro, bone repairing capabilities have not been clarified after in vivo implantation up to now. In situ grown composites (IGC) of hydroxyapatite (HA) and poly(DL‐lactide) (PDLLA) were obtained from electrospun fibers grafted with gelatin as the induction sites for HA growth. The presence and location of HA nanoparticles within electrospun fibers were proposed to affect the degradation and repairing process of femoral defects. Subcutaneous implantation of IGC led to around 90% of mass loss and 75% of molecular weight reduction during 16 weeks, which were significantly higher than those after in vitro degradation in buffer solutions. In vitro tests on MC3T3‐E1 cells indicated that IGC acted as a better cell support to provide favorable conditions for cell proliferation and to stimulate the osteogenic differentiation as compared with electrospun PDLLA fibers, and blend electrospun fibrous composites. Femoral defects were created for in vivo evaluation of bone repairing, indicating that the entire defect was filled by newly formed bone with compact structure after 16 week implantation of IGC. Histological and SEM observations demonstrated a successful bridging of the critical‐sized defect with rapid mineralization, continual remodeling, and abundant vasculature. The in situ grown HA nanoparticles on the surface of electrospun fibers improved the biocompatibility with defect sites, promoted the bone formation within fibrous scaffolds and enhanced the bone remodeling, indicating potentials for bone regeneration and repairing of bone defects. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2012.
Adipogenesis on biphasic calcium phosphate using rat adipose‐derived mesenchymal stem cells: In vitro and in vivo
Authors: Venugopal Balu , Fernandez Francis B. , Babu Suresh S. , Harikrishnan V. S. , Varma Harikrishna , John Annie
Published: February 2012

Developing adipose tissue‐engineered construct to mend soft tissue defects arising from traumatic injury, tumor resections, and maxillofacial abnormalities is of prime importance in plastic and reconstructive surgical procedures. It is apparent that the clinical outcome of classic techniques like adipose tissue transplantation is unpredictable, with graft resorption, lack of vascularization, and impaired functionality. In this prospective, the concept of tissue engineering was adopted to fabricate a combination product with biphasic calcium phosphate (BCP) and rat adipose‐derived mesenchymal stem cells (ASCs) toward the development of an adipose tissue construct. BCP, a combination of hydroxyapatite and α‐tricalcium phosphate, was characterized for its physiochemical properties, and ASCs were characterized for their stemness. The cell–ceramic interactions were demonstrated in vitro, whereas adipogenesis was picturesquely depicted by Nile red‐stained multilocular adipocyte‐like cells. Subsequently, the three‐dimensional cell–ceramic‐engineered construct was implanted in the rat dorsal muscle for a period of 3 weeks to demonstrate the efficacy of the tissue construct in vivo. Interestingly, the histology of the postimplanted tissue construct revealed the distribution of chicken wire net‐like fat cells within the vicinity of the construct. The efficacy of cell transplantation via the scaffold was traced using fluorescent in situ hybridization by labeling the Y chromosome. Thus, the ceramic‐based construct may be a good option for reconstruction therapies. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2012.
Prosecution Rate and Quality of the Investigative Interview in Child Sexual Abuse Cases
Authors: Hagborg Johan Melander , Strömwall Leif A. , Tidefors Inga
Published: February 2012

One suggested reason for the low prosecution rate in child sexual abuse cases is the poor quality of the interviews. The present study examined the extent to which a number of aspects of interview quality were used by interviewers at a Children's Advocacy Centre in Sweden. Furthermore, the relationship between aspects of interview quality and the prosecution rate was examined. Transcripts of investigative interviews with 3‐year‐old to 16‐year‐old children who all reported on sexual abuse were assessed (n = 32). There were no effects found concerning the relationship between prosecution rate on the one hand, and interview quality, age, and the child's relationship with the suspected offender on the other. The interviews with older children were, on several aspects, scored as higher in quality. The relationships between these findings and child sexual abuse investigations and interviews are discussed. Copyright © 2012 John Wiley & Sons, Ltd.
Combined magnitude and phase‐based segmentation of the cerebral cortex in 7T MR images of the elderly
Authors: Doan Nhat Trung , van Rooden Sanneke , Versluis Maarten J. , Webb Andrew G. , van der Grond Jeroen , van Buchem Mark A. , Reiber Johan H.C. , Milles Julien
Published: February 2012

Purpose:

To propose a new method that integrates both magnitude and phase information obtained from magnetic resonance (MR) T*2‐weighted scans for cerebral cortex segmentation of the elderly.

Materials and Methods:

This method makes use of K‐means clustering on magnitude and phase images to compute an initial segmentation, which is further refined by means of transformation with reconstruction criteria. The method was evaluated against the manual segmentation of 7T in vivo MR data of 20 elderly subjects (age = 67.7 ± 10.9). The added value of combining magnitude and phase was also evaluated by comparing the performance of the proposed method with the results obtained when limiting the available data to either magnitude or phase.

Results:

The proposed method shows good overlap agreement, as quantified by the Dice Index (0.79 ± 0.04), limited bias (average relative volume difference = 2.94%), and reasonable volumetric correlation (R = 0.555, p = 0.011). Using the combined magnitude and phase information significantly improves the segmentation accuracy compared with using either magnitude or phase.

Conclusion:

This study suggests that the proposed method is an accurate and robust approach for cerebral cortex segmentation in datasets presenting low gray/white matter contrast. J. Magn. Reson. Imaging 2012;36:99–109. © 2012 Wiley Periodicals Inc.
Generalized eigenvalue passivity assessment of descriptor systems with applications to symmetric and singular systems
Authors: Knockaert L. , Ferranti F. , Dhaene T.
Published: February 2012

This paper proposes general eigenvalue‐based passivity tests for descriptor state space systems, extending the already available tests for standard state space systems. Generalized eigenvalue tests are proposed to identify passivity violations in the positive‐real and bounded‐real cases. The important practical case of singular descriptor state space systems is also treated. The proposed passivity tests for descriptor systems can be used in the important case of symmetric (reciprocal) systems, as symmetric systems can always be cast in an explicitly reciprocal descriptor state space format. Also, passivity violation assessment methods are developed in the important case of strictly proper symmetric systems, as in that case the classical test matrices for passivity assessment are undefined. Finally, some pertinent numerical examples are given to demonstrate the usefulness and scope of the different passivity violation assessment tests. Copyright © 2012 John Wiley & Sons, Ltd.
How do leaders use emotional labor?
Authors: Humphrey Ronald H.
Published: February 2012

Leaders use emotional labor to regulate their own emotions and to manage the moods, job attitudes, and performance of their followers. Researchers need to examine how emotional labor is related to (i) leadership styles, (ii) leader and subordinate stress and well‐being, (iii) leader authenticity and character, and (iv) leader effectiveness. Copyright © 2012 John Wiley & Sons, Ltd.
Preoperative embolization of replaced right hepatic artery prior to pancreaticoduodenectomy
Authors: Cloyd Jordan M. , Chandra Venita , Louie John D. , Rao Sekhar , Visser Brendan C.
Published: February 2012

Aberrancy of the hepatic arterial anatomy is common. Because of its course directly adjacent to the head of the pancreas, a replaced right hepatic artery (RHA) is vulnerable to invasion by peri‐pancreatic malignancies. Division of the RHA at the time of pancreaticoduodenectomy, however, may result in hepatic infarction and/or bilioenteric anastomotic complications. We report two cases of patients undergoing preoperative embolization of tumor encased replaced RHAs to allow for sufficient collateralization prior to pancreaticoduodenectomy. J. Surg. Oncol. 2012; 106:509–512. © 2012 Wiley Periodicals, Inc.
Wideband acoustic transfer functions predict middle‐ear effusion
Authors: Ellison John C. , Gorga Michael , Cohn Edward , Fitzpatrick Denis , Sanford Chris A. , Keefe Douglas H.
Published: February 2012

Objectives/Hypothesis:

Compare the accuracy of wideband acoustic transfer functions (WATFs) measured in the ear canal at ambient pressure to methods currently recommended by clinical guidelines for predicting middle‐ear effusion (MEE).

Study Design:

Cross‐sectional validating diagnostic study among young children with and without MEE to investigate the ability of WATFs to predict MEE.

Methods:

WATF measures were obtained in an MEE group of 44 children (53 ears; median age, 1.3 years) scheduled for middle‐ear ventilation tube placement and a normal age‐matched control group of 44 children (59 ears; median age, 1.2 years) with normal pneumatic otoscopic findings and no history of ear disease or middle‐ear surgery. An otolaryngologist judged whether MEE was present or absent and rated tympanic‐membrane (TM) mobility via pneumatic otoscopy. A likelihood‐ratio classifier reduced WATF data (absorbance, admittance magnitude and phase) from 0.25 to 8 kHz to a single predictor of MEE status. Absorbance was compared to pneumatic otoscopy classifications of TM mobility.

Results:

Absorbance was reduced in ears with MEE compared to ears from the control group. Absorbance and admittance magnitude were the best single WATF predictors of MEE, but a predictor combining absorbance, admittance magnitude, and phase was the most accurate. Absorbance varied systematically with TM mobility based on data from pneumatic otoscopy.

Conclusions:

Results showed that absorbance is sensitive to middle‐ear stiffness and MEE, and WATF predictions of MEE in young children are as accurate as those reported for methods recommended by the clinical guidelines. Laryngoscope, 2012