bluuebunny/crossref_metadata_2025 huggingface dataset:
Diminished Bone Strength Is Observed in Adult Women and Men Who Sustained a Mild Trauma Distal Forearm Fracture During Childhood
Authors: Farr Joshua N , Khosla Sundeep , Achenbach Sara J , Atkinson Elizabeth J , Kirmani Salman , McCready Louise K , Melton L Joseph , Amin Shreyasee
Published: April 2014

Children and adolescents who sustain a distal forearm fracture (DFF) owing to mild, but not moderate, trauma have reduced bone strength and cortical thinning at the distal radius and tibia. Whether these skeletal deficits track into adulthood is unknown. Therefore, we studied 75 women and 75 men (age range, 20 to 40 years) with a childhood (age <18 years) DFF and 150 sex-matched controls with no history of fracture using high-resolution peripheral quantitative computed tomography (HRpQCT) to examine bone strength (ie, failure load) by micro–finite element (µFE) analysis, as well as cortical and trabecular bone parameters at the distal radius and tibia. Level of trauma (mild versus moderate) was assigned using a validated classification scheme, blind to imaging results. When compared to sex-matched, nonfracture controls, women and men with a mild trauma childhood DFF (eg, fall from standing height) had significant reductions in failure load (p < 0.05) of the distal radius, whereas women and men with a moderate trauma childhood DFF (eg, fall while riding a bicycle) had values similar to controls. Consistent findings were observed at the distal tibia. Furthermore, women and men with a mild trauma childhood DFF had significant deficits in distal radius cortical area (p < 0.05), and significantly lower dual-energy X-ray absorptiometry (DXA)-derived bone density at the radius, hip, and total body regions compared to controls (all p < 0.05). By contrast, women and men with a moderate trauma childhood DFF had bone density, structure, and strength that did not differ significantly from controls. These findings in young adults are consistent with our observations in children/adolescents with DFF, and they suggest that a mild trauma childhood DFF may presage suboptimal peak bone density, structure, and strength in young adulthood. Children and adolescents who suffer mild trauma DFFs may need to be targeted for lifestyle interventions to help achieve improved skeletal health. © 2014 American Society for Bone and Mineral Research.
Sclerostin Deficiency Is Linked to Altered Bone Composition
Authors: Hassler Norbert , Roschger Andreas , Gamsjaeger Sonja , Kramer Ina , Lueger Sonja , van Lierop Antoon , Roschger Paul , Klaushofer Klaus , Paschalis Eleftherios P , Kneissel Michaela , Papapoulos Socrates
Published: April 2014

High bone mass in animals and humans with sclerostin deficiency is associated with increased bone strength, which is not the case for all disorders with high bone mineral density, some of which are even associated with fragility fractures owing to unfavorable bone composition. In the current study we investigated whether alterations in bone composition may contribute to the bone strength characteristics associated with lack of sclerostin. We examined cortical bone of Sost-knockout (KO) mice (n = 9, 16 weeks old) and sclerosteosis patients (young [4 to 14 years], n = 4 and adults [24 and 43 years], n = 2) by quantitative backscattered electron imaging and Raman microspectroscopy and compared it to bone from wild-type mice and healthy subjects, respectively. In Sost-KO mice endocortical bone exhibited altered bone composition, whereas subperiosteal bone was unchanged. When comparing endocortical bone tissue of identical tissue age as defined by sequential dual fluorochrome labeling the average bone matrix mineralization was reduced −1.9% (p < 0.0001, younger tissue age) and −1.5% (p < 0.05, older tissue age), and the relative proteoglycan content was significantly increased. Similarly, bone matrix mineralization density distribution was also shifted toward lower matrix mineralization in surgical samples of compact bone of sclerosteosis patients. This was associated with an increase in mineralization heterogeneity in the young population. In addition, and consistently, the relative proteoglycan content was increased. In conclusion, we observed decreased matrix mineralization and increased relative proteoglycan content in bone subcompartments of Sost-KO mice—a finding that translated into sclerosteosis patients. We hypothesize that the altered bone composition contributes to the increased bone strength of patients with sclerostin deficiency. © 2014 American Society for Bone and Mineral Research.
Reactivity index based on orbital energies
Authors: Tsuneda Takao , Singh Raman K.
Published: April 2014

This study shows that the chemical reactivities depend on the orbital energy gaps contributing to the reactions. In the process where a reaction only makes progress through charge transfer with the minimal structural transformation of the reactant, the orbital energy gap gradient (OEGG) between the electron‐donating and electron‐accepting orbitals is proven to be very low. Using this relation, a normalized reaction diagram is constructed by plotting the normalized orbital energy gap with respect to the normalized intrinsic reaction coordinate. Application of this reaction diagram to 43 fundamental reactions showed that the majority of the forward reactions provide small OEGGs in the initial stages, and therefore, the initial processes of the forward reactions are supposed to proceed only through charge transfer. Conversely, more than 60% of the backward reactions are found to give large OEGGs implying very slow reactions associated with considerable structural transformations. Focusing on the anti‐activation‐energy reactions, in which the forward reactions have higher barriers than those of the backward ones, most of these reactions are shown to give large OEGGs for the backward reactions. It is also found that the reactions providing large OEGGs in the forward directions inconsistent with the reaction rate constants are classified into SN2, symmetric, and methyl radical reactions. Interestingly, several large‐OEGG reactions are experimentally established to get around the optimum pathways. This indicates that the reactions can take significantly different pathways from the optimum ones provided no charge transfer proceeds spontaneously without the structural transformations of the reactants. © 2014 Wiley Periodicals, Inc.
Antiretroviral drug resistance among antiretroviral‐naïve and treatment experienced patients infected with HIV in Iran
Authors: Baesi Kazem , Ravanshad Mehrdad , Ghanbarisafari Maryam , Saberfar Esmaeil , SeyedAlinaghi SeyedAhmad , Volk Jonathan E.
Published: April 2014

Resistance to antiretroviral therapy (ART) threatens the success of programs to reduce HIV morbidity and mortality, particularly in countries with few treatment options. In the present study, genotype and phenotype data from ART‐naïve and experienced hospitalized patients infected with HIV in Tehran, Iran were used to assess the prevalence and types of transmitted (TDR) and acquired drug resistance (ADR) mutations. All 30 participants naïve to ART and 62 of 70 (88.6%) participants receiving ART had detectable viral loads. Among participants receiving ART with sequencing data available (n = 62), 36 (58.1%) had at least one drug resistance mutation; the most common mutations were K103N (21.0%), M184V (19.4%), and the thymidine analogue mutations. Seven (11.3%), 27 (43.5%), and two (3.2%) of these participants had resistance to one, two, and three drug classes, respectively. High‐level resistance to efavirenz (EFV) was more common among participants on EFV‐based regimens than high‐level lopinavir/ritonivar (LPV/r) resistance among those on LPV/r‐based regimens (55.3% vs. 6.7%, P < 0.0001). Two (6.7%) antiretroviral‐naïve participants had K103N mutations. These findings document an alarmingly high frequency of multiple HIV drug class resistance in Iran, confirm the presence of TDR, and highlight the need for systematic viral load monitoring and drug resistance testing, including at diagnosis. Expanded access to new antiretroviral medications from additional drug classes is needed. J. Med. Virol. 86:1093–1098, 2014. © 2014 Wiley Periodicals, Inc.
Ossification defects detected in CT scans represent early osteochondrosis in the distal femur of piglets
Authors: Olstad Kristin , Kongsro Jørgen , Grindflek Eli , Dolvik Nils Ivar
Published: April 2014

The purpose of the current study was to validate the use of CT for selection against osteochondrosis in pigs by calculating positive predictive value and comparing it to the positive predictive value of macroscopic evaluation, using histological examination as the reference standard. Eighteen male, hereditarily osteochondrosis‐predisposed piglets underwent terminal examination at biweekly intervals from the ages of 82–180 days old, including CT scanning, macroscopic, and histological evaluation of the left distal femur. Areas of ischemic chondronecrosis (osteochondrosis) were confirmed in histological sections from 44/56 macroscopically suspected lesions, resulting in a positive predictive value of 79% (95% CI: 67–84%). Suspected lesions, that is; focal, radiolucent defects in the ossification front in CT scans corresponded to areas of ischemic chondronecrosis in 36/36 histologically examined lesions, resulting in a positive predictive value of 100% (95% CI: 90–100%). CT was superior to macroscopic evaluation for diagnosis of early stages of osteochondrosis in the distal femur of piglets. The current histologically validated observations can potentially be extrapolated to diagnostic monitoring of juvenile osteochondritis dissecans in children, or to animal models of human juvenile articular cartilage injury and repair. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:1014–1023, 2014.
Thermoelectric‐based temperature‐controlling system for in‐tube solid‐phase microextraction
Authors: Yang Yang , Rodriguez‐Lafuente Angel , Pawliszyn Janusz
Published: April 2014

A temperature‐controlling device for in‐tube solid‐phase microextraction was developed based on thermoelectric cooling and heating. This device can control the temperature of the capillary column from 0 to 100°C by applying a voltage to a Peltier cooler or stainless steel tube. The extraction temperatures for angiotensin I, propranolol, and ranitidine were optimized. In all cases, setting the temperature to 10°C for extraction achieved the best extraction efficiency. Desorption showed minimum peak broadening at 70°C, contributing to better chromatographic performance. Propranolol was selected as a model compound to compare the performance of temperature‐controlled in‐tube solid‐phase microextraction at optimized conditions. Calibration curves exhibited good linearity (R2 > 0.999) over the studied range, and the limit of detection and limit of quantification were about three times lower than those obtained at standard conditions (30°C extraction and desorption).
Screening epidermal growth factor receptor antagonists from Radix et Rhizoma Asari by two‐dimensional liquid chromatography
Authors: Han Shengli , Huang Jing , Hou Jingjing , Wang Sicen
Published: April 2014

Radix et Rhizoma Asari is a traditional Chinese medicine, and has many pharmacological effects, such as calming, analgesia, anti‐inflammation, antiarrhythmic, antihypertensive, antivirus, etc. But few studies have screened the active compounds from extracts of Radix et Rhizoma Asari for tumor therapy. In this study, a two‐dimensional liquid chromatography system was built to screen active compounds acting on epidermal growth factor receptor (EGFR) from Radix et Rhizoma Asari. The screening result showed that asarinin from Radix et Rhizoma Asari was the targeted component that could act on EGFR specificity. The competitive binding assay and molecular docking assay results showed asarinin binding with EGFR in similar manner as with gefitinib, which was used as a positive control drug. Then the antitumor effect of asarinin was studied through cell growth assay in vitro. The results showed that gefitinib and asarinin could inhibit highly expressed EGFR cell growth in a dose‐dependent manner in the range of dose from 0.10 to 102.4 μM. This two‐dimensional liquid chromatography system will be a useful method in drug discovery from natural medicinal herbs for searching potential antitumor candidates.
Electrospun Nanofiber Scaffolds and Plasma Polymerization: A Promising Combination Towards Complete, Stable Endothelial Lining for Vascular Grafts
Authors: Savoji Houman , Hadjizadeh Afra , Maire Marion , Ajji Abdellah , Wertheimer Michael R. , Lerouge Sophie
Published: April 2014

In the quest to reduce risk of thrombosis in vascular grafts, it is essential to provide a surface with morphological and mechanical properties close to those of the extracellular matrix beneath the luminal endothelium, and to favor the growth of a confluent, stable monolayer of endothelial cells. This is accomplished here by combining electrospun poly(ethylene terephthalate) (PET) mats with an amine‐rich thin plasma‐polymerized coating, designated “L‐PPE:N.” Its deposition does not modify the open, highly porous mats and leads only to small changes in mechanical properties. L‐PPE:N significantly improves the adhesion and growth of human umbilical vein endothelial cells (HUVEC) and their resistance to flow‐induced shear stress. These properties favor the formation of desired confluent HUVEC monolayers on the topmost surface, unlike conventional vascular grafts (ePTFE or woven PET), where cells migrate inside the material. This combination is therefore highly advantageous for the pre‐endothelialization of the luminal side of small‐diameter vascular prostheses.
Sequential pH‐Dependent Adsorption of Ionic Amphiphilic Diblock Copolymer Micelles and Choline Oxidase Onto Conductive Substrates: Toward the Design of Biosensors
Authors: Sigolaeva Larisa V. , Günther Ulrike , Pergushov Dmitry V. , Gladyr Snezhana Yu. , Kurochkin Ilya N. , Schacher Felix H.
Published: April 2014

This work examines the fabrication regime and the properties of polymer–enzyme thin‐films adsorbed onto conductive substrates (graphite or gold). The films are formed via two‐steps, sequential adsorption of poly(n‐butylmethacrylate)‐block‐poly(N,N‐dimethylaminoethyl methacrylate) (PnBMA‐b‐PDMAEMA) diblock copolymer micelles (1st step of adsorption), followed by the enzyme choline oxidase (ChO) (2nd step of adsorption). The solution properties of both adsorbed components are studied and the pH‐dependent step‐by‐step fabrication of polymer–enzyme biosensor coatings reveals rather drastic differences in their enzymatic activities in dependence on the pH of both adsorption steps. The resulting hybrid thin‐films represent highly active biosensors for choline with a low detection limit of 30 nM and a good linearity in a range between 30 nM and 100 μM. The sensitivity is found to be 175 μA mM−1 cm−2 and the operational stability of the polymer–enzyme thin‐films can be additionally improved via enzyme‐to‐enzyme crosslinking with glutaraldehyde.
Effect of Particle Size and Shape on the Reinforcing Efficiency of Nanoparticles in Polymer Nanocomposites
Authors: Hassanabadi Hojjat Mahi , Rodrigue Denis
Published: April 2014

The effect of particle characteristics such as size and shape on the reinforcing efficiency of nano‐particles is investigated. Nanocomposites based on ethylene vinyl acetate (EVA) copolymer containing five different nano‐particles including clay, multiwall carbon nanotube (CNT), CaCO3, talc, and nano‐crystalline cellulose (NCC) were produced. The analyses are performed in the melt and solid states. The highest property changes were obtained for clay and CNT, followed by talc, NCC, and CaCO3. By using morphological analyses, mechanical properties, and rheological data, the results were correlated to the amount of available surface area between the particles and polymer. Finally, the particles were compared using a material cost over mechanical performance ratio where the optimum was obtained for talc followed by clay, NCC, CNT and CaCO3.
Amenability of compact hypergroup algebras
Authors: Amini Massoud , Medghalchi Ali Reza
Published: April 2014

We show that for a compact hypergroup K, the hypergroup algebra is amenable as a Banach algebra if the set of hyperdimensions of irreducible representations of K is bounded above. Conversely if is amenable, the set of ratios of the hyperdimension to the dimension of irreducible representations of K is bounded above. These are equivalent for compact commutative hypergroups.
Spatial Control over Brush Growth through Sunlight‐Induced Atom Transfer Radical Polymerization Using Dye‐Sensitized TiO2 as a Photocatalyst
Authors: Li Bin , Yu Bo , Zhou Feng
Published: April 2014

Simulated‐sunlight induced atom transfer radical polymerization is used for spatial control over polymer brush growth by in situ photo‐generation of the CuI/L activator complex from its higher oxidation state CuII/L deactivator complex using dye sensitized titanium dioxide nano­particles. The polymerization is well controlled under sunlight irradiation. Another attractive feature of this method is the possibility of creating various patterned surfaces of brushes using photomasks. When a nanoporous alumina oxide membrane is used as the template for confinement diffusion of photogenerated CuI/L catalyst, patterns with sub‐50 nm resolution are obtained.

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Conjugated Polymer Patterning through Photooxidative Backbone Cleavage
Authors: Johnson Ross S. , Haworth Jacob J. , Finnegan Patrick S. , Wheeler David R. , Dirk Shawn M.
Published: April 2014

Photolithographic patterning of a xanthate precursor to poly(3,4‐diphenyl‐2,5‐thienylene vinylene) is described. Unlike xanthate precursors to poly(p‐phenylene vinylene), the thienylene vinylene analogue patterns as a positive tone resist. Characterization of irradiated films reveals photooxidative cleavage of the vinylene linker decreases the molecular weight of the polymer (increasing the solubility of the UV‐exposed areas). As a result of the mechanism, the developed pattern sees no UV light exposure, which is a significant advantage compared with negative‐tone‐conjugated polymer resists. Single micron resolution of a low‐bandgap polymer is achieved in an efficient and scalable process.

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The Influence of Structure on Mechanical Properties of Filler Networks Via Coarse‐Grained Modeling
Authors: Xi He , Hentschke Reinhard
Published: April 2014

We extend a previously introduced coarse‐grained computer model for the simulation of the amplitude and frequency dependence of dynamic moduli in filled elastomers. An algorithm is developed, which allows the generation of close to realistic filler structures. The latter significantly influences the compounds mechanical properties, in particular above a certain threshold concentration, where the mixing process causes the formation of a spanning filler network. Its basic units are “unbreakable” aggregates consisting of primary filler particles. The aggregates form, by comparison, loosely bound agglomerates, which in turn form the network largely responsible for the final compound's mechanical properties. We study the breakup of the network on the level of the agglomerates under mechanical stress and the attendant reduction of the storage modulus including its relation to the network structure.
Surface structure influences contact killing of bacteria by copper
Authors: Zeiger Marco , Solioz Marc , Edongué Hervais , Arzt Eduard , Schneider Andreas S.
Published: April 2014

Copper kills bacteria rapidly by a mechanism that is not yet fully resolved. The antibacterial property of copper has raised interest in its use in hospitals, in place of plastic or stainless steel. On the latter surfaces, bacteria can survive for days or even weeks. Copper surfaces could thus provide a powerful accessory measure to curb nosocomial infections. We here investigated the effect of the copper surface structure on the efficiency of contact killing of Escherichia coli, an aspect which so far has received very little attention. It was shown that electroplated copper surfaces killed bacteria more rapidly than either polished copper or native rolled copper. The release of ionic copper was also more rapid from electroplated copper compared to the other materials. Scanning electron microscopy revealed that the bacteria nudged into the grooves between the copper grains of deposited copper. The findings suggest that, in terms of contact killing, more efficient copper surfaces can be engineered.
Propeller flap reconstruction of abdominal defects: Review of the literature and case report
Authors: Scaglioni Mario F. , Giuseppe Alberto Di , Chang Edward I.
Published: April 2014

The abdominal wall is perfused anteriorly by the superior and deep epigastric vessels with a smaller contribution from the superficial system. The lateral abdominal wall is perfused predominantly from perforators arising from the intercostal vessels. Reconstruction of soft tissue defects involving the abdomen presents a difficult challenge for reconstructive surgeons. Pedicle perforator propeller flaps can be used to reconstruct defects of the abdomen, and here we present a thorough review of the literature as well as a case illustrating the perforasome propeller flap concept. A patient underwent resection for dermatofibrosarcoma protuberans resulting in a large defect of the epigastric soft tissue. A propeller flap was designed based on a perforator arising from the superior deep epigastric vessels and was rotated 90° into the defect allowing primary closure of the donor site. The patient healed uneventfully and was without recurrent disease 37 months following reconstruction. Perforator propeller flaps can be used successfully in reconstruction of abdominal defects and should be incorporated into the armamentarium of reconstructive microsurgeons already facile with perforator dissections. © 2014 Wiley Periodicals, Inc. Microsurgery 35:72–78, 2015.
Virus transcript levels and cell growth rates after naturally occurring HPV16 integration events in basal cervical keratinocytes
Authors: Scarpini Cinzia G , Groves Ian J , Pett Mark R , Ward Dawn , Coleman Nicholas
Published: April 2014

Cervical carcinogenesis is characterized by a clonal selection process in which the high‐risk human papillomavirus (HRHPV) genome usually changes from the extra‐chromosomal (episomal) state seen in productive infections to DNA that is integrated into host chromosomes. However, it is not clear whether all HRHPV integration events provide cells with a selective growth advantage compared with the episome‐containing cells from which they originate. It is also unclear whether selection of cells containing a particular integrant from a mixed population simply reflects the highest levels of virus oncogene expression or has additional determinants. These early events in cervical carcinogenesis cannot readily be addressed by cross‐sectional studies of clinical samples. We used the W12 model system to generate a panel of cervical squamous cell clones that were derived from an identical background under non‐competitive conditions and differed only by the genomic site of HPV16 integration. Compared with the ‘baseline’ episome‐containing cells from which they were isolated, only 9/17 clones (53%) showed significantly greater growth rates and only 7/17 (41%) showed significantly greater expression of the major virus oncogenes E7/E6. There were significant variations in levels of HPV16 transcription per DNA template, changes that were associated with histone modifications in the integrated virus chromatin. Cell growth rates showed only weak and non‐significant associations with protein and mRNA levels for E7, E6, and the mean E7/E6 values. We conclude that HPV16 integration in basal cervical cells does not necessarily lead to increased levels of virus oncogenes, or to a competitive growth advantage, when compared with the initiating episome‐containing cells. © 2014 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.
Neutrophil extracellular traps promote differentiation and function of fibroblasts
Authors: Chrysanthopoulou Akrivi , Mitroulis Ioannis , Apostolidou Eirini , Arelaki Stella , Mikroulis Dimitrios , Konstantinidis Theocharis , Sivridis Efthimios , Koffa Maria , Giatromanolaki Alexandra , Boumpas Dimitrios T , Ritis Konstantinos , Kambas Konstantinos
Published: April 2014

Neutrophil activation by inflammatory stimuli and the release of extracellular chromatin structures (neutrophil extracellular traps – NETs) have been implicated in inflammatory disorders. Herein, we demonstrate that NETs released by neutrophils treated either with fibrosis‐related agents, such as cigarette smoke, magnesium silicate, bleomycin, or with generic NET inducers, such as phorbol 12‐myristate 13‐acetate, induced activation of lung fibroblasts (LFs) and differentiation into myofibroblast (MF) phenotype. Interestingly, the aforementioned agents or IL‐17 (a primary initiator of inflammation/fibrosis) had no direct effect on LF activation and differentiation. MFs treated with NETs demonstrated increased connective tissue growth factor expression, collagen production, and proliferation/migration. These fibrotic effects were significantly decreased after degradation of NETs with DNase1, heparin or myeloperoxidase inhibitor, indicating the key role of NET‐derived components in LF differentiation and function. Furthermore, IL‐17 was expressed in NETs and promoted the fibrotic activity of differentiated LFs but not their differentiation, suggesting that priming by DNA and histones is essential for IL‐17‐driven fibrosis. Additionally, autophagy was identified as the orchestrator of NET formation, as shown by inhibition studies using bafilomycin A1 or wortmannin. The above findings were further supported by the detection of NETs in close proximity to alpha‐smooth muscle actin (α‐SMA)‐expressing fibroblasts in biopsies from patients with fibrotic interstitial lung disease or from skin scar tissue. Together, these data suggest that both autophagy and NETs are involved not only in inflammation but also in the ensuing fibrosis and thus may represent potential therapeutic targets in human fibrotic diseases. Copyright © 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd
Facile Synthesis of Porous MnO Microspheres for High‐Performance Lithium‐Ion Batteries
Authors: Li Xiuwan , Shang Xiaonan , Li Dan , Yue Hongwei , Wang Suiyan , Qiao Li , He Deyan
Published: April 2014

Manganese oxide is a highly promising anode material of lithium‐ion batteries (LIBs) for its low insertion voltage and high reversible capacity. Porous MnO microspheres are prepared by a facile method in this work. As an anode material of LIB, it can deliver a high reversible capacity up to 1234.2 mA h g−1 after 300 cycles at 0.2 C, and a capacity of 690.0 mA h g−1 in the 500th cycle at 2 C. The capacity increase with cycling can be attributed to the growth of reversible polymer/gel‐like film, and the better cycling stability and the superior rate performance can be attributed to the featured structure of the microspheres composed of nanoparticles with a short transport path for lithium ions, a large specific surface, and material/electrolyte contact area. The results suggest that the porous MnO microspheres can function as a promising anode material for high‐performance LIBs.
Atrial fibrillation: current approaches to management
Authors: Tayal Upasana , Greenbaum Robert
Published: April 2014

A trial fibrillation is the commonest arrhythmia and GPs have an important role to play in management. Our Drug review discusses its diagnosis and current recommended treatment, followed by sources of further information.
Providing support to patients who wish to quit smoking
Authors: Pang Elizabeth , Stern Myra
Published: April 2014

Smoking cessation is the most cost‐effective intervention for the prevention and treatment of smoking‐related disease. Here, the authors discuss the available products for aiding smoking cessation and how to support patients wishing to quit.
The effect of baroclinicity on the wind in the planetary boundary layer
Authors: Floors R. , Peña A. , Gryning S‐E.
Published: April 2014

The influence of baroclinicity on wind within the planetary boundary layer was investigated using two years of wind lidar measurements collected at a suburban site in northern Germany (Hamburg) and a rural‐coastal site in western Denmark (Høvsøre). Measurements were made up to a height of 950 m. The surface geostrophic wind, the surface gradient wind and the gradient wind were estimated using the pressure and geopotential fields from a mesoscale model. At both sites the atmospheric flow was typically baroclinic. The distribution of the geostrophic wind shear was approximately Gaussian with a mean close to zero and a standard deviation of approximately 3 m s−1km−1. The geostrophic wind shear had a strong seasonal dependence because of temperature differences between land and sea. The mean wind profile in Hamburg, observed during an intensive campaign using radio sounding and during the whole year using the wind lidar, was influenced by baroclinicity. For easterly winds at Høvsøre, the estimated gradient wind decreased rapidly with height, resulting in a mean low‐level jet. The turning of the wind in the boundary layer, the boundary‐layer height and the empirical constants in the geostrophic drag law were found to be dependent on baroclinicity for neutral conditions.
Rational design of outer‐expanded purine analogues as building blocks of DNA‐based nanowires with enhanced electronic properties
Authors: Liu Haiying , Li Genqin , Zhao Peng , Chen Gang , Bu Yuxiang
Published: April 2014

Due to the fact that natural DNA may lack sufficient conductance for direct application in molecular electronics, a novel design of outer‐expanded purine analogues was proposed by incorporating an aromatic ring at the N7‐C8 site into natural G and A bases from the outside. The effect of the outer‐expansion modification on electronic properties of DNA was investigated by density functional theory and molecular dynamics. The analyses revealed that these purine analogues not only preserve the same sizes of natural purine bases, thus avoiding distortions of DNA skeleton induced by the normal ring‐inner‐expansion modification, but also keep the selectivity of pairing with their natural counterpart C and T bases. More importantly, their electronic properties are enhanced, indicated by the narrowed HOMO–LUMO gaps, the lowered ionization potentials and the improved ultraviolet absorption spectra. This work may provide helpful information for designing of artificial bases as promising building blocks of biomolecular nanowires. © 2014 Wiley Periodicals, Inc.
Determination of13C/12C ratios of endogenous urinary 5‐amino‐imidazole‐4‐carboxamide 1β‐D‐ribofuranoside (AICAR)
Authors: Piper Thomas , Thomas Andreas , Baume Norbert , Sobolevsky Timothy , Saugy Martial , Rodchenkov Grigory , Schänzer Wilhelm , Thevis Mario
Published: April 2014

RATIONALE

AICAR (5‐aminoimidazole‐4‐carboxamide 1β‐D‐ribofuranoside) is prohibited in sport according to rules established by the World Anti‐Doping Agency. Doping control laboratories identify samples where AICAR abuse is suspected by measuring its urinary concentration and comparing the observed level with naturally occurring concentrations. As the inter‐individual variance of urinary AICAR concentrations is large, this approach requires a complementary method to unambiguously prove the exogenous origin of AICAR. Therefore, a method for the determination of carbon isotope ratios (CIRs) of urinary AICAR has been developed and validated.

METHODS

Concentrated urine samples were fractionated by means of liquid chromatography for analyte cleanup. Derivatization of AICAR yielding the trimethylsilylated analog was necessary to enable CIR determinations by gas chromatography/combustion/isotope ratio mass spectrometry. The method was tested for its repeatability and stability over time and a linear mixing model was applied to test for possible isotopic discrimination. A reference population of n = 63 males and females was investigated to calculate appropriate reference limits to differentiate endogenous from exogenous urinary AICAR. These limits were tested by an AICAR elimination study.

RESULTS

The developed method fulfills all the requirements for adequate sports drug testing and was found to be fit for purpose. The investigated reference population showed a larger variability in the CIR of AICAR than of the endogenous steroids. Nevertheless, the calculated thresholds for differences between AICAR and endogenous steroids can be applied straightforwardly to evaluate suspicious doping control samples with the same statistical confidence as established e.g. for testosterone misuse. These thresholds enabled the detection of a single oral AICAR administration for more than 40 h.

CONCLUSIONS

Determination of thee CIRs is the method of choice to distinguish between an endogenous and an exogenous source of urinary AICAR. The developed method will enable investigations into doping control samples with elevated urinary concentrations of AICAR and clearly differentiate between naturally produced/elevated and illicitly administered AICAR. Copyright © 2014 John Wiley & Sons, Ltd.
Electrospray ionization tandem mass spectrometry study of six isomeric cationic amphiphiles with ester/amide linker
Authors: Vijay Darshan D. , Chandar B. G. N. , Srujan M. , Chaudhuri A. , Prabhakar S.
Published: April 2014

RATIONALE

Isomeric cationic amphiphiles differing only in the orientation of the linker group have been demonstrated to possess dramatically changed gene transfer efficacies. Studies aimed at understanding structure‐stability correlations of such isomeric cationic amphiphiles at the molecular level are yet to be undertaken. Such studies may throw significant new insights into the mechanistic origin on their contrasting bioactivities.

METHODS

Electrospray ionization mass spectrometry (ESI‐MS) and multi‐stage tandem mass spectrometric (MSn) experiments were performed on a LCQ ion trap mass spectrometer. The decomposition pathway was confirmed by high‐resolution mass spectrometry data from a quadrupole time‐of‐flight (Q‐TOF) mass spectrometer. Dissociation curves were drawn based on the intensities of precursor and product ions.

RESULTS

The collision‐induced dissociation (CID) spectra of the M+ ion of each isomeric pair showed distinct product ions (3 pairs). Normal esters (1 and 3) showed abundant product ions with a neighboring group participation (NGP) reaction and reverse esters (lipid 2 and 4) showed McLafferty rearrangement product ions. The spectra of a normal amide (5) and a reverse amide (6) are similar to that found in the corresponding ester, except for the absence of the McLafferty rearrangement in 6. Dissociation curves revealed that normal esters/amide decompose at lower energy than those of corresponding reverse esters/amide.

CONCLUSIONS

The lipids which easily decompose (flexible) show dramatically enhanced gene delivery capabilities and the lipids which decompose at higher collision energy (CE) values (rigid) are transfection incompetent. Copyright © 2014 John Wiley & Sons, Ltd.
Who Needs 3D When the Universe Is Flat?
Authors: ERIKSSON URBAN , LINDER CEDRIC , AIREY JOHN , REDFORS ANDREAS
Published: April 2014

An overlooked feature in astronomy education is the need for students to learn to extrapolate three‐dimensionality and the challenges that this may involve. Discerning critical features in the night sky that are embedded in dimensionality is a long‐term learning process. Several articles have addressed the usefulness of three‐dimensional (3D) simulations in astronomy education, but they have neither addressed what students discern nor the nature of that discernment. A Web‐based questionnaire was designed using links to video clips drawn from a simulation video of travel through our galaxy and beyond. The questionnaire was completed by 137 participants from nine countries across a broad span of astronomy education. The descriptions provided by the participants were analyzed using hermeneutics in combination with a constant comparative approach to formulate six categories of discernment in relation to multidimensionality. These results are used to make the case that the ability to extrapolate three‐dimensionality calls for the creation of meaningful motion parallax experiences.
Phase‐Field Modeling of the Dendrite Growth Morphology with Influence of Solid–Liquid Interface Effects
Authors: Rezende Joao , Senk Dieter , Hüttenmeister Dennis
Published: April 2014

High manganese steels are able to deform by the TRIP effect, TWIP effect and microbanding formation. These steels are quite promising materials for mechanical construction, once they show an unusual combination of high ductility and high tensile strength. The casting of these steels represents a technological challenge, because they are extremely prone to macro‐ and microsegregation. Segregation, on its turn, may locally impair the desired mechanical properties. Simulations by the phase‐field method may be utilized to investigate microstructure formation and the development of microsegregation patterns during solidification. Nevertheless, performing reliable microstructure simulations is only possible when reliable values for the solid–liquid interface energy are available. Through utilization of the sessile‐drop method, first measurements of the interface energy in the Fe–Mn–C alloy system were performed. By utilizing the obtained values for the interface energy as an input, phase‐field simulations were run aiming at investigating both the effect of the value for the interface energy and of the steel composition on the dendrite morphology.
Sonographic diagnosis of lateral asynclitism: a new subtype of fetal head malposition as a main determinant of early labor arrest
Authors: Ghi T. , Bellussi F. , Pilu G.
Published: April 2014

We report on the sonographic appearance of a new type of fetal head malposition in labor that has not been previously described systematically. In some circumstances, the fetal lie is characterized by a lateral orientation of the head with respect to the trunk and, on suprapubic ultrasound, a transverse section of the fetal chest together with the facial profile can be seen on the same image. These sonographic findings were documented in five cases of first‐stage labor arrest. This report illustrates how, in these circumstances, ultrasound might be helpful in clarifying the precise cause of obstructed labor. [[ArtCopyrightmsg]]
Thermopressurized diluted phosphoric acid pretreatment of ligno(hemi)cellulose to make free sugars and nutraceutical oligosaccharides
Authors: Tiboni Marcela , Grzybowski Adelia , Baldo Gizele Rejane , Dias Edson Flausino , Tanner Robert D , Kornfield Julia Ann , Fontana José Domingos
Published: April 2014

Ligno(hemi)cellulosics (L(h)Cs) as sugarcane bagasse and loblolly pine sawdust are currently being used to produce biofuels such as bioethanol and biobutanol through fermentation of free sugars that are often obtained enzymatically. However, this bioconversion requires a pretreatment to solubilize the hemicellulose fractions, thus facilitating the action of the cellulolytic enzymes. Instead of the main free monosaccharides used in these current models, the modulation of thermopressurized orthophosphoric acid as a pretreatment, in the ranges of 3–12 atm and pH 1.5–2.5, can produce nondigestible oligosaccharides (NDOS) such as xylo-oligosaccharides (XOS) because heteroxylan is present in both types of hardwood and softwood hemicelluloses. A comparative thin-layer chromatographic analysis of the hydrolytic products showed the best conditions for NDOS production to be 7 atm/water, pH 2.25 and 2.50, and 8.5 atm/water for both sources. Particular hydrolysates from 7 atm (171 °C) at pHs 2.25 and 2.50 both for cane bagasse and pine sawdust, with respective oligosaccharide contents of 57 and 59 %, once mixed in a proportion of 1:1 for each plant source, were used in vitro as carbon sources for Bifidobacterium or Lactobacillus. Once both bacteria attained the stationary phase of growth, an unforeseen feature emerged: the preference of B. animalis for bagasse hydrolysates and, conversely, the preference of L. casei for pine hydrolysates. Considering the fact that nutraceutical oligosaccharides from both hemicelluloses correspond to higher value-added byproducts, the technology using a much diluted thermopressurized orthophosphoric acid pretreatment becomes an attractive choice for L(h)Cs.
Twisted Witt Groups of Flag Varieties
Authors: Zibrowius Marcus
Published: April 2014

Calmès and Fasel have shown that the twisted Witt groups of split flag varieties vanish in a large number of cases. For flag varieties over algebraically closed fields, we sharpen their result to an if-and-only-if statement. In particular, we show that the twisted Witt groups vanish in many previously unknown cases. In the non-zero cases, we find that the twisted total Witt group forms a free module of rank one over the untwisted total Witt group, up to a difference in grading.

Our proof relies on an identification of the Witt groups of flag varieties with the Tate cohomology groups of their K-groups, whereby the verification of all assertions is eventually reduced to the computation of the (twisted) Tate cohomology of the representation ring of a parabolic subgroup.
Dissolution-driven porous-medium convection in the presence of chemical reaction
Authors: Ward T. J. , Cliffe K. A. , Jensen O. E. , Power H.
Published: April 2014

Motivated by processes occurring during ${\mathrm{CO}}_2$ sequestration in an underground saline aquifer, we examine two-dimensional convection in a finite-depth porous medium induced by a solute introduced at the upper boundary. Once dissolved, the solute concentration is assumed to decay via a first-order chemical reaction, restricting the depth over which solute can penetrate the domain. Using spectral and asymptotic methods, we explore the resulting convective mixing using linear stability analysis, computation of nonlinear steady solution branches and time-dependent simulations, as a function of Rayleigh number, Damköhler number and domain size. Long-wave eigenmodes show how deep recirculation can be driven by a shallow solute field while explicit approximations are derived for the growth of short-wave eigenmodes. Steady solution branches undergo numerous secondary bifurcations, forming an intricate network of mixed states. Although many of these states are unstable, some play an important role in organising the phase space of time-dependent states, providing approximate bounds for time-averaged mixing rates.
Analysis of complex singularities in high-Reynolds-number Navier–Stokes solutions
Authors: Gargano F. , Sammartino M. , Sciacca V. , Cassel K. W.
Published: April 2014

Numerical solutions of the laminar Prandtl boundary-layer and Navier–Stokes equations are considered for the case of the two-dimensional uniform flow past an impulsively-started circular cylinder. The various viscous–inviscid interactions that occur during the unsteady separation process are investigated by applying complex singularity analysis to the wall shear and streamwise velocity component of the two solutions. This is carried out using two different methodologies, namely a singularity-tracking method and the Padé approximation. It is shown how the van Dommelen and Shen singularity that occurs in solutions of the Prandtl boundary-layer equations evolves in the complex plane before leading to a separation singularity in finite time. Navier–Stokes solutions, computed at different Reynolds numbers in the range$10^3 \leq Re \leq 10^5$, are characterized by the presence of various complex singularities that can be related to different physical interactions acting over multiple spatial scales. The first interaction developing in the separation process is large-scale interaction that is visible for all the Reynolds numbers considered, and it signals the first relevant differences between the Prandtl and Navier–Stokes solutions. For$Re\geq O(10^4)$, a small-scale interaction follows the large-scale interaction. The onset of these interactions is related to the characteristic changes of the streamwise pressure gradient on the circular cylinder. Even if these interactions physically differ from that prescribed by the Prandtl solution, and they set a possible limit on the comparison of Prandtl solutions with Navier–Stokes solutions, it is shown how the asymptotic validity of boundary-layer theory is strongly supported by the results that have been obtained through the complex singularity analysis.
Transport equation for the mean turbulent energy dissipation rate in low- grid turbulence
Authors: Djenidi L. , Antonia R. A.
Published: April 2014

A direct numerical simulation (DNS) based on the lattice Boltzmann method (LBM) is carried out in low-Reynolds-number grid turbulence to analyse the mean turbulent kinetic energy dissipation rate, $\overline{\epsilon }$, and its transport equation during decay. All the components of $\overline{\epsilon }$ and its transport equation terms are computed, providing for the first time the opportunity to assess the contribution of each term to the decay. The results indicate that although small departures from isotropy are observed in the components of $\overline{\epsilon }$ and its destruction term, there is sufficient compensation among the components for these two quantities to satisfy isotropy to a close approximation. A short distance downstream of the grid, the transport equation of $\overline{\epsilon }$ simplifies to its high-Reynolds-number homogeneous and isotropic form. The decay rate of $\overline{\epsilon }$ is governed by the imbalance between the production due to vortex stretching and the destruction caused by the action of viscosity, the latter becoming larger than the former as the distance from the grid increases. This imbalance, which is not constant during the decay as argued by Batchelor & Townsend (Proc. R. Soc. Lond. A, vol. 190, 1947, pp. 534–550), varies according to a power law of $x$, the distance downstream of the grid. The non-constancy implies a lack of dynamical similarity in the mechanisms controlling the transport of $\overline{\epsilon }$. This is consistent with the fact that the power-law-decay ($\overline{q^2} \sim x^n$) exponent $n$ is not equal to $-$1. It is actually close to $-$1.6, a value in keeping with the relatively low Reynolds number of the simulation. These results highlight the importance of the imbalance in establishing the value of $n$. The $\overline{\epsilon }$-transport equation is also analysed in relation to the power-law decay. The results show that the power-law exponent $n$ is controlled by the imbalance between production and destruction. Further, a relatively straightforward analysis provides information on the behaviour of $n$ during the entire decay process and an interesting theoretical result, which is yet to be confirmed, when $R_{\lambda } \rightarrow 0 $, namely, the destruction coefficient $G$ is constant and its value must lie between $15/7$ and $30/7$. These two limits encompass the predictions for the final period of decay by Batchelor & Townsend (1947) and Saffman (J. Fluid Mech., vol. 27, 1967, pp. 581–593).
Scattering of internal tides by irregular bathymetry of large extent
Authors: Li Yile , Mei Chiang C.
Published: April 2014

We present an analytical theory of scattering of tide-generated internal gravity waves in a continuously stratified ocean with a randomly rough seabed. Based on a linearized approximation, the idealized case of constant mean sea depth and Brunt–Väisälä frequency is considered. The depth fluctuation is assumed to be a stationary random function of space, characterized by small amplitude and a correlation length comparable to the typical wavelength. For both one- and two-dimensional topographies the effects of scattering on the wave phase over long distances are derived explicitly by the method of multiple scales. For one-dimensional topography, numerical results are compared with Bühler & Holmes-Cerfon (J. Fluid Mech., vol. 678, 2011, pp. 271–293), computed by the method of characteristics. For two-dimensional topography, new results are presented for both statistically isotropic and anisotropic cases.