bluuebunny/crossref_metadata_2025 huggingface dataset:
Cerebral glucose metabolism on positron emission tomography of children
Authors: Shan Zuyao Y. , Leiker Andrew J. , Onar‐Thomas Arzu , Li Yimei , Feng Tianshu , Reddick Wilburn E. , Reutens David C. , Shulkin Barry L.
Published: July 2013

Establishing the normative range of age‐dependent fluorodeoxyglucose (FDG) uptake in the developing brain is necessary for understanding regional quantitative analysis of positron emission tomography (PET) brain images in children and also to provide functional information on brain development. We analyzed head sections of FDG PET/computed tomography (CT) images for 115 patients (5 months to 23 years) without central nervous system disease before treatment, as PET studies are not performed on healthy children owing to ethical considerations and the risk of radiation exposure. We investigated the changes in FDG uptake and established age‐associated normative ranges of cerebral FDG. Head sections of FDG PET/CT images were registered to a population‐based probabilistic atlas of human cortical structures. Gray matter of 56 brain structures was defined on normalized PET images according to the atlas. To avoid individual and experimental confounding factors, the relative standardized uptake value (SUV) over the cerebellum of each structure was calculated. Relative SUVs were analyzed by ANOVA and modeled using generalized estimating equalization analysis with false discovery rate control. Age and structure were significant factors affecting SUVs. Anatomic proximity had little effect on FDG uptake. Linear and quadratic developmental trajectories were observed on absolute and relative SUVs, respectively. An increase from posterior‐to‐anterior and superior‐to‐inferior pattern was observed in both absolute SUV increase rate and relative SUV peak age. The SUV of each structure was modeled with respect to age, and these models can serve as baselines for the quantitative analysis of cerebral FDG–PET images of children. Hum Brain Mapp 35:2297–2309, 2014. © 2013 Wiley Periodicals, Inc.
Novel function for the p38‐MK2 signaling pathway in circulating CD1c+ (BDCA‐1+) myeloid dendritic cells from healthy donors and advanced cancer patients; inhibition of p38 enhances IL‐12 whilst suppressing IL‐10
Authors: Franks Hester A. , Wang Qunwei , Lax Stephanie J. , Collins Mary K. , Escors David , Patel Poulam M. , Jackson Andrew M.
Published: July 2013

There is growing interest in myeloid (my) dendritic cells (DC) as an alternative to monocyte‐derived DC (moDC) for immunotherapy. However, in contrast to moDC, little is known regarding the effect of malignancy on the function, abundance or use of intracellular signaling pathways in myDC. Understanding the molecular detail of circulating myDC is therefore important for future use in advanced cancer. Advanced cancer patients had similar numbers of circulating myDC to cancer‐free patients and healthy individuals, and secreted similar levels of IL‐1β, IL‐6, IL‐10, IL‐12 and IL‐23. However, myDC from some patients failed to secrete the Th1‐cytokine IL‐12. Surprisingly, inhibiting p38 (p38i) signaling (using BIRB0796 or SB203580) markedly increased IL‐12 secretion by myDC. This is in complete contrast to what is established for moDC where inhibiting p38 ablates IL‐12. Interestingly, this was specific to IL‐12, since IL‐10 was suppressed by p38i in both DC types. The opposing effect of p38i on IL‐12 was evident at the transcriptional level and in both DC types was mediated through the p38‐MK2 pathway but did not involve differential phosphorylation of the distal Rsk kinase. Importantly, where patient myDC did not secrete IL‐12 (or after treatment with suppressive melanoma lysate), p38i restored IL‐12 to normal levels. In contrast to p38, inhibiting the other MAPK pathways had similar consequences in both DC types. We show for the first time the differential use of a major intracellular signaling pathway by myDC. Importantly, there are sufficient circulating myDC in advanced cancer patients to consider development of adoptive immunotherapy.
Deuterium isotope effect on the suicide inactivation of tyrosinase in its action on o‐diphenols
Authors: Muñoz‐Muñoz Jose Luis , del Mar García‐Molina María , Garcia‐Molina Francisco , Garcia‐Ruiz Pedro Antonio , Garcia‐Sevilla Francisco , Rodriguez‐Lopez Jose N. , Garcia‐Canovas Francisco
Published: July 2013

A solvent deuterium isotope effect on the inactivation suicide of tyrosinase in its action on o‐diphenols (catechol, 4‐methylcatechol, and 4‐tert‐butylcatechol) was observed. This isotope effect, observed during kinetic studies in the transition phase, was higher than that described previously in the steady state, indicating that there is an additional slow step in the suicide inactivation mechanism, which we believe to be responsible for the inactivation. In a proton inventory study of oxidation of o‐diphenols, the representation of
versus n (atom fractions of deuterium), where
is the maximum apparent inactivation constant for a molar fraction of deuterium (n) and
is the corresponding kinetic parameter in a water solution, was linear for all substrates. This suggests that only one of the protons transferred from the two hydroxyl groups of the substrate, which are oxidized in one turnover, is responsible for the isotope effects. We propose that this proton could be the proton transferred from the hydroxyl group of C‐2 to the hydroperoxide of the oxytyrosinase form (Eox) and that it probably causes enzyme inactivation through the reduction of the Cu2+A to Cu0 and its subsequent release from the active site. © 2013 IUBMB Life, 65(9):793–799,
2013
Protease‐activated receptor 2 in dorsal root ganglion contributes to peripheral sensitization of bone cancer pain
Authors: Liu S. , Liu Y.‐P. , Yue D.‐M. , Liu G.‐J.
Published: July 2013

Background

Treating bone cancer pain continues to be a major clinical challenge, and the underlying mechanisms of bone cancer pain remain elusive. Protease‐activated receptor 2 (PAR2) has been reported to be involved in neurogenic inflammation, nociceptive pain and hyperalgesia. Here, we investigated the role of PAR2 in bone cancer pain development.

Methords

Expression of PAR2, mechanical allodynia, thermal hyperalgesia and neurochemical alterations induced by bone cancer pain were analysed in male, adult C3H/HeJ mice with tumour cell implantation (TCI). To investigate the contribution of PAR2 to bone cancer pain, PAR2 antagonist peptide and PAR2 knockout mice were used.

Results

TCI produced bone cancer‐related pain behaviours. Production and persistence of these pain behaviours were well correlated with TCI‐induced up‐regulation of PAR2 in sciatic nerve and dorsal root ganglia (DRG). PAR2 knockout and spinal administration of PAR2 antagonist peptide prevented and/or reversed bone cancer‐related pain behaviours and associated neurochemical changes in DRG and dorsal horn (DH). TCI also induced proteases release in tumour‐bearing tibia, sciatic nerve and DRG. Plantar injection of supernatant from sarcoma cells induced PAR2 up‐regulation and intracellular calcium [Ca2+]i increase in DRG, and calcitonin gene‐related peptide accumulation in DH, as well as significant thermal and mechanical hyperalgesia, which were all in PAR2‐dependent manners.

Conclusion

These findings suggest that PAR2 may be a key mediator for peripheral sensitization of bone cancer pain. Inhibiting PAR2 activation, especially during the early phase, may be a new therapy for preventing/suppressing development of bone cancer pain.
Does tobramycin impregnation of allograft bone affect implant fixation? – An experimental study in 12 dogs
Authors: Barckman Jeppe , Baas Jorgen , Sorensen Mette , Lange Jeppe , Bechtold Joan E. , Soballe Kjeld
Published: July 2013

Clinical trials have used antibiotic impregnated impacted bone allograft in revisions of infected arthroplasties. By this method high local antibiotic concentration and good control of infection was achieved. Toxicity studies, however, suggest that high local antibiotic concentration can impair osteoblast replication. We therefore asked whether impregnating morselized allograft bone with different quantities of tobramycin before impaction would impair implant fixation. We implanted three cylindrical (10 mm × 6 mm) porous‐coated titanium implants into the distal femurs of 12 dogs. The implants were surrounded by a circumferential gap of 2.5 mm into which a standardized volume of morselized allograft bone, with or without tobramycin, was impacted. In each animal, the bone graft was impregnated with either 0 mg (control), 50 mg (low dose), or 200 mg (high dose) of tobramycin per 1 mL of bone graft. At the end of the 4 weeks experimental period, the implants with surrounding bone were evaluated by histomorphometric analysis and mechanical push‐out test. We found no difference between the treatment groups regarding new bone formation, bone graft resorption, or implant fixation. There was, however, a tendency toward a decrease in implant fixation with higher tobramycin dose. The present study is unable to provide evidence on whether the use of topical tobramycin with allograft is safe or whether it indeed can impair implant fixation. The tendency toward an impaired implant fixation warrants further preclinical studies. Its current clinical use should be weighed against its possible positive effects on preventing infection in complicated revisions. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 102B: 173–180, 2014.
Safety, tolerability, and pharmacokinetics of oral and intravenous administration of GSK1322322, a peptide deformylase inhibitor
Authors: Naderer Odin J. , Jones Lori S. , Zhu John , Kurtinecz Milena , Dumont Etienne
Published: July 2013

GSK1322322 is the first in a new class of antibiotics that targets peptide deformylase (PDF), an essential bacterial enzyme required for protein maturation. This randomized, double‐blind, placebo‐controlled, eight‐cohort phase I trial enrolled 62 healthy volunteers to assess safety, tolerability, and pharmacokinetic profiles of GSK1322322. GSK1322322 was administered as a single oral or intravenous (IV) dose, escalating from 500 to 3,000 mg or repeat IV doses escalating from 500 to 1,500 mg twice daily. Upon repeat IV administration, GSK1322322 exhibits linear pharmacokinetics over time upon repeat doses as shown by time‐invariant pharmacokinetics. A dose‐proportional increase in area under concentration‐time curve was observed after single or repeat IV dosing, whereas clearance at steady state remained generally unchanged across doses. There was minimal accumulation of GSK1322322 after repeat IV twice‐daily administration. After oral tablet doses of GSK1322322 1,000 and 1,500 mg, absolute bioavailability was 69% and 56%, respectively. GSK1322322 administration at single and repeat IV doses and at supratherapeutic single IV doses of 2,000 and 3,000 mg was associated with mild‐to‐moderate drug‐related adverse events. On the basis of the pharmacokinetics and tolerability demonstrated in this study, GSK1322322 has the potential to become the first‐in‐class PDF inhibitor for clinical use.
Co‐medication of pravastatin and paroxetine—A categorical study
Authors: An Li , Ravindran Priyadarshini P. , Renukunta Swetha , Denduluri Srinivas
Published: July 2013

Electronic Medical Records (EMRs) are wealthy storehouses of patient information, to which data mining techniques can be prudently applied to reveal clinically significant patterns. Detecting patterns in drug–drug interactions, leading to adverse drug reactions is a powerful application of EMR data mining. Adverse effects of drug treatments can be investigated by mining clinical laboratory tests data which are reliable indicators of abnormal physiological functions. We report here the co‐medication effects of pravastatin (HMG‐CoA reductase inhibitor) and paroxetine (selective serotonin reuptake inhibitor (SSRI) anti‐depressant) on significant clinical parameters, identified through a data mining analysis conducted on the Allscripts data warehouse. We found that the concomitant drug treatments of pravastatin and paroxetine increased the mean values of glucose serum from 113.2 to 132.1 mg/dL and international normalized ratio (INR) from 2.18 to 2.52, respectively. It also decreased the mean values of estimated glomerular filtration rate (eGFR) from 43 to 37 mL/min/1.73 m3 and blood CO2 levels from 24.8 to 23.9 mEq/L respectively. Our findings indicate that co‐medication of pravastatin and paroxetine might have significant impact on blood anti‐coagulation, kidney function, and glucose homeostasis. Our methodology can be applied to any EMR data set to reveal co‐medication effects of any drug pairs.
Effect of final irrigation protocols on microhardness and erosion of root canal dentin
Authors: Aranda‐Garcia Arturo Javier , Kuga Milton Carlos , Chavéz‐Andrade Gisselle Moraima , Kalatzis‐Sousa Natália Guimarães , Hungaro Duarte Marco Antonio , Faria Gisele , Reis Só Marcus Vinicius , Faria‐Junior Norberto Batista
Published: July 2013

The aim of this study was to evaluate the effect of final irrigation protocols (17% EDTA, BioPure MTAD, SmearClear, and QMiX) on microhardness and erosion of root canal dentin. Fifty roots were sectioned transversely at the cement–enamel junction and each root was sectioned horizontally into 4‐mm‐thick slices. The samples were divided into five groups (n = 10) according to the final irrigation protocol: G1: distilled water (control group); G2: 17% EDTA; G3: BioPure MTAD; G4: SmearClear; and G5: QMiX. The dentin microhardness was then measured with a load of 25 g for 10 s. Initially, the reference microhardness values were obtained for the samples without any etching. The same samples were then submitted to the final irrigation protocols. A new measure was realized and the difference between before and after the procedures was the dentin microhardness reduction. In sequence, the specimens were submitted to SEM analysis to verify the dentinal erosion. The Kruskal Wallis and Dunn tests (α = 5%) were used to compare the results. The dentin microhardness decreased for all final irrigation protocols. There was no significant difference between groups 2, 3, 4, and 5 (P > 0.05), but this groups presented significant dentin microhardness reduction than G1 (P < 0.05). In G2, occurred the highest incidence of dentinal erosion (P < 0.05). 17% EDTA, BioPure MTAD, SmearClear, and QMiX promoted significant dentin microhardness reduction. Dentinal tubules erosion was promoted by 17% EDTA. Microsc. Res. Tech., 76:1079–1083, 2013. © 2013 Wiley Periodicals, Inc.
The pattern of surface waves in a shallow free surface flow
Authors: Horoshenkov K. V. , Nichols A. , Tait S. J. , Maximov G. A.
Published: July 2013

This work presents new water surface elevation data including evidence of the spatial correlation of water surface waves generated in shallow water flows over a gravel bed without appreciable bed forms. Careful laboratory experiments have shown that these water surface waves are not well‐known gravity or capillary waves but are caused by a different physical phenomenon. In the flow conditions studied, the shear present in shallow flows generates flow structures, which rise and impact on the water‐air interface. It is shown that the spatial correlation function observed for these water surface waves can be approximated by the following analytical expression . The proposed approximation depends on the spatial correlation radius, σw, characteristic spatial period, L0, and spatial lag, ρ. This approximation holds for all the hydraulic conditions examined in this study. It is shown that L0 relates to the depth‐averaged flow velocity and carries information on the shape of the vertical velocity profile and bed roughness. It is also shown that σw is related to the hydraulic roughness and the flow Reynolds number.
Dynamics of component carbon fluxes in a semi‐arid Acacia woodland, central Australia
Authors: Cleverly James , Boulain Nicolas , Villalobos‐Vega Randol , Grant Nicole , Faux Ralph , Wood Cameron , Cook Peter G. , Yu Qiang , Leigh Andrea , Eamus Derek
Published: July 2013

Vast areas in the interior of Australia are exposed to regular but infrequent periods of heavy rainfall, interspersed with long periods at high temperatures, but little is known of the carbon budget of these remote areas or how they respond to extreme precipitation. In this study, we applied three methods to partition net ecosystem photosynthesis into gross primary production (GPP) and ecosystem respiration (Re) during two years of contrasting rainfall. The first year was wet (>250 mm above average rainfall), while little precipitation fell during the second year (>100 mm below average). During the first year of study, rates of GPP were large (793 g C m−2 yr−1) in this semi‐arid Mulga (Acacia aneura) and grass savanna due to complementary photosynthetic responses by the canopy and C4 understorey to cycles of heavy rainfall. Patterns in GPP during the summer and autumn matched those in leaf area index (LAI), photosynthetic activity, and autotrophic respiration. During the dry year, small but positive photosynthetic uptake by Mulga contributed to the neutral carbon budget (GPP / Re = 1.06 ± 0.03). Small rates of photosynthesis by evergreen Mulga when dry were supported by storage of soil moisture above a relatively shallow hardpan. Little soil organic matter (1.1%) was available to support heterotrophic respiration (Rh) without input of fresh substrate. The two largest sources of Re in this study were autotrophic respiration by the seasonal understorey and Rh through decomposition of fresh organic matter supplied by the senescent understorey.
Development of novel PET probes, [18F]BCPP‐EF, [18F]BCPP‐BF, and [11C]BCPP‐EM for mitochondrial complex 1 imaging in the living brain
Authors: Harada Norihiro , Nishiyama Shingo , Kanazawa Masakatsu , Tsukada Hideo
Published: July 2013

We developed three novel positron‐emission tomography (PET) probes, 2‐tert‐butyl‐4‐chloro‐5‐{6‐[2‐(2[18F]fluoroethoxy)‐ethoxy]‐pyridin‐3‐ylmethoxy}‐2H‐pyridazin‐3‐one ([18F]BCPP‐EF), 2‐tert‐butyl‐4‐chloro‐5‐[6‐(4‐[18F]fluorobutoxy)‐pyridin‐3‐ylmethoxy]‐2H‐pyridazin‐3‐one ([18F]BCPP‐BF), and 2‐tert‐butyl‐4‐chloro‐5‐{6‐[2‐(2‐[11C]methoxy‐ethoxy)‐ethoxy]‐pyridin‐3‐ylmethoxy}‐2H‐pyridazin‐3‐one ([11C]BCPP‐EM), for quantitative imaging of mitochondrial complex 1 (MC‐1) activity in vivo. These three PET probes were successfully labeled by nucleophilic [18F]fluorination or by [11C]methylation of their corresponding precursor with sufficient radioactivity yield, good radiochemical purity, and sufficiently high specific radioactivity for PET measurement. The specificity of these probes for binding to MC‐1 was assessed with rotenone, a specific MC‐1 inhibitor, by a rat brain slice imaging method in vitro. Rat whole‐body imaging by small‐animal PET demonstrated that all probes showed high uptake levels in the brain as well as in the heart sufficient to image them clearly. The rank order of uptake levels in the brain and the heart just after injection was as follows: high in [18F]BCPP‐BF, intermediate in [11C]BCPP‐EM, and low in [18F]BCPP‐EF. The kinetics of [18F]BCPP‐EF and [11C]BCPP‐EM provided a reversible binding pattern, whereas [18F]BCPP‐BF showed nonreversible accumulation‐type kinetics in the brain and heart. Metabolite analyses indicated that these three compounds were rapidly metabolized in the plasma but relatively stable in the rat brain up to 60 min post‐injection. The present study demonstrated that [18F]BCPP‐EF could be a useful PET probe for quantitative imaging of MC‐1 activity in the living brain by PET.
Near‐field optical enhancement by lead‐sulfide quantum dots and metallic nanoparticles for SERS
Authors: Hutter Tanya , Mahajan Sumeet , Elliott Stephen R.
Published: July 2013

There is a growing interest in using quantum dots (QDs) and metallic nanoparticles (NPs), both for luminescence enhancement and surface‐enhanced Raman scattering (SERS). Here, we study the electromagnetic‐field enhancement that can be generated by lead‐sulfide (PbS) QDs using three‐dimensional finite‐element simulations. We investigate the field enhancement associated with combinations of PbS QDs with metallic NPs and substrates. The results show that high field enhancement can be achieved by combining PbS QDs with metallic NPs of larger sizes. The ideal size for Ag NPs is 25 nm, providing a SERS enhancement factor of ~5*108 for light polarization parallel to the NP dimer axis and a gap of 0.6 nm. For Au NPs, the bigger the size, the higher is the field for the studied diameters, up to 50 nm. The near‐field values for PbS QDs above metallic substrates were found to be lower compared to the case of PbS QD‐metal NP dimers. This study provides the understanding for the design and application of QDs for the enhancement of near‐field phenomena. Copyright © 2013 John Wiley & Sons, Ltd.
Ionic‐liquid‐functionalized magnetic particles as an adsorbent for the magnetic SPE of sulfonylurea herbicides in environmental water samples
Authors: He Zeying , Liu Donghui , Zhou Zhiqiang , Wang Peng
Published: July 2013

In this paper, a new ionic‐liquid‐functionalized magnetic material was prepared based on the immobilization of an ionic liquid on silica magnetic particles that could be successfully used as an adsorbent for the magnetic SPE of five sulfonylurea herbicides (bensulfuron‐methyl, prosulfuron, pyrazosulfuron‐ethyl, chlorimuron‐ethyl and triflusulfuron‐methyl) from environmental water samples. The main parameters affecting the extraction efficiency such as desorption conditions, sample pH, extraction time and so on, were optimized using the Taguchi method. Good linearities were obtained with correlation coefficients ranging from 0.9992 to 0.9999 in the concentration range of 0.1–50 μg L−1 and the LODs were 0.053–0.091 μg L−1. Under the optimum conditions, the enrichment factors of the method were 1155–1380 and the recoveries ranged from 77.8 to 104.4%. The proposed method was reliable and could be applied to the residue analysis of sulfonylurea herbicides in environmental water samples (tap, reservoir and river).
Prevention of pressure ulcers after pediatric tracheotomy using a Mepilex Ag dressing
Authors: Kuo Connie Y. , Wootten Christopher T. , Tylor Dale A. , Werkhaven Jay A. , Huffman Kimberly F. , Goudy Steven L.
Published: July 2013

Objectives/Hypothesis

Skin irritation and ulceration beneath the tracheostomy tube or ties secondary to pressure and shearing forces on the skin frequently complicate pediatric tracheotomy in the immediate postoperative period. The aim of this study is to determine the effectiveness of Mepilex Ag dressings in reducing posttracheotomy wound complications.

Study Design

Retrospective study.

Methods

We identified 134 pediatric tracheotomies performed between June 2005 and June 2011 at a tertiary care academic pediatric hospital. Peristomal skin breakdown was documented at the time of the first tracheostomy tube change. Starting in February 2010, the application of Mepilex Ag, a silver‐impregnated foam dressing, underneath the tracheostomy tube and twill ties became standard practice. The rates of wound breakdown before and after the introduction of Mepilex Ag were compared. Age, indication for tracheotomy, comorbidities, and severity of wound breakdown were also compared.

Results

Patients undergoing tracheotomies prior to February 2010 had no dressing applied under the tracheotomy at the end of the procedure (n = 93). Beginning in February 2010, Mepilex Ag barrier was applied beneath the tracheostomy and ties in all subjects undergoing tracheotomy (n = 41). In the cohort without Mepilex Ag, 11.8% developed skin breakdown by the time of first tracheostomy tube change. When Mepilex Ag was used to pad the tracheotomy site, no peristomal skin breakdown occurred (P = 0.02). No comorbidities were associated with postoperative ulcer formation in either cohort.

Conclusions

The use of Mepilex Ag after pediatric tracheotomy reduces the occurrence of postoperative peristomal pressure ulcers.

Level of Evidence

4. Laryngoscope, 123:3201–3205, 2013
RGS21, a regulator of taste and mucociliary clearance?
Authors: Kimple Adam J. , Garland Alaina L. , Cohen Staci P. , Setola Vincent , Willard Francis S. , Zielinski Thomas , Lowery Robert G. , Tarran Robert , Siderovski David P.
Published: July 2013

Objectives/Hypothesis

Motile cilia of airway epithelial cells help to expel harmful inhaled material. Activation of bitterant‐responsive G protein‐coupled receptors (GPCRs) is believed to potentiate cilia beat frequency and mucociliary clearance. In this study, we investigated whether regulator of G protein signaling‐21 (RGS21) has the potential to modulate signaling pathways connected to airway mucociliary clearance, given that RGS proteins modulate GPCR signaling by acting as GTPase‐accelerating proteins (GAPs) for the Gα subunits of heterotrimeric G proteins.

Study Design

This is a pilot investigation to determine if RGS21, a potential tastant specific RGS gene, is expressed in sinonasal mucosa, and to determine its specific Gα substrate using in vitro biochemical assays with purified proteins.

Methods

Rgs21 expression in sinonasal mucosa was determined using quantitative, real‐time PCR and a transgenic mouse expressing RFP from the Rgs21 promoter. Rgs21 was cloned, over‐expressed, and purified using multistep protein chromatography. Biochemical and biophysical assays were used to determine if RGS21 could bind and accelerate the hydrolysis of GTP on heterotrimeric Gα subunits.

Results

Rgs21 was expressed in sinonasal mucosa and lingual epithelium. Purified recombinant protein directly bound and accelerated GTP hydrolysis on Gα subunits.

Conclusions

Rgs21 is expressed in sinonasal mucosa, is amenable to purification as a recombinant protein, and can bind to Gαi/o/q subunits. Furthermore, RGS21 can accelerate the hydrolysis rate of GTP on Gαi subunits. This provides evidence that RGS21 may be a negative regulator of bitterant responses. Future studies will be needed to determine the physiological role of this protein in mucociliary clearance.

Level of Evidence

N/A. Laryngoscope, 124:E56–E63, 2014
Organic light‐emitting transistors with voltage‐tunable lit area and full channel illumination
Authors: Toffanin Stefano , Capelli Raffaella , Koopman Wouter , Generali Gianluca , Cavallini Susanna , Stefani Andrea , Saguatti Davide , Ruani Giampiero , Muccini Michele
Published: July 2013

Organic light‐emitting transistors (OLETs) are multifunctional optoelectronic devices that hold great promise for a variety of applications, including flat panel displays, integrated light sources for sensing and optical communication systems. The narrow illumination area within the device channel is considered intrinsic to the device architecture and is a severe technological drawback for all those applications where a controlled, wide and homogeneous emission area is required. Here it is shown that not only the position but also the extension of the emission area is voltage‐tunable, and the entire channel of the transistor can be homogeneously illuminated. The modeling of the exciton distribution within the channel at the different bias conditions coupled to the modeling of the device emission profile highlights that excitons are spread through the entire channel width and across the bulk of the central emission layer of the p‐channel/emitter/n‐channel trilayer active heterostructure.
Strategic Corporate Social Responsibility Activities and Corporate Governance in Imperfectly Competitive Markets
Authors: Manasakis Constantine , Mitrokostas Evangelos , Petrakis Emmanuel
Published: July 2013

We investigate the incentives of firms' owners to commit voluntarily to corporate social responsibility (CSR) activities in an oligopolistic market. The socially responsible attributes attached to products are considered as credence goods, with consumers forming expectations about their existence and level. We show that hiring an ‘individually’ socially responsible CEO and delegating to him the CSR effort and market decisions acts as a commitment device for the firm's owners and credibly signals to consumers that the firm will undertake the ‘missioned’ CSR activities. We also find that CSR activities are welfare enhancing for consumers and firms and thus, they should be encouraged. Copyright © 2013 John Wiley & Sons, Ltd.
Helix capping
Authors: Aurora Rajeev , Rosee George D.
Published: July 2013

Helix‐capping motifs are specific patterns of hydrogen bonding and hydrophobic interactions found at or near the ends of helices in both proteins and peptides. In an α‐helix, the first four >N‐H groups and last four >C=O groups necessarily lack intrahelical hydrogen bonds. Instead, such groups are often capped by alternative hydrogen bond partners. This review enlarges our earlier hypothesis (Presta LG, Rose GD. 1988. Helix signals in proteins. Science 240:1632‐1641) to include hydrophobic capping. A hydrophobic interaction that straddles the helix terminus is always associated with hydrogen‐bonded capping. From a global survey among proteins of known structure, seven distinct capping motifs are identified‐three at the helix N‐terminus and four at the C‐terminus. The consensus sequence patterns of these seven motifs, together with results from simple molecular modeling, are used to formulate useful rules of thumb for helix termination. Finally, we examine the role of helix capping as a bridge linking the conformation of secondary structure to supersecondary structure.
Spatially and spectrally resolved cathodoluminescence with fast electrons: A tool for background subtraction in luminescence intensity second‐order correlation measurements applied to subwavelength inhomogeneous diamond nanocrystals
Authors: Tizei Luiz Henrique Galvão , Meuret Sophie , Nagarajan Sounderya , Treussart François , Fang Chia‐Yi , Chang Huan‐Cheng , Kociak Mathieu
Published: July 2013

Measurements of the photon second‐order correlation function, g(2)(τ), is a common tool for the characterization of single photon emitters, like nitrogen‐vacancy color centers in diamond. Such measurement requires background photoluminescence correction, which is easy when this background is homogeneous on a few wavelengths scale. However, if the sample contains emitting centers separated by a distance smaller than the optical diffraction limit, and having different and overlapping emission, these background correction techniques cannot be applied. We have recently shown that cathodoluminescence (CL) can be used to measure g(2)(τ) at the subwavelength scale. Here we propose a method, based on spatially and spectrally resolved CL, to subtract the background taking into account the nanometer spatial distribution of the emitted light. To this end, a nanometer‐resolved spectrum image is acquired on the same region where the g(2)(τ) is measured. As an example, we show the use of this method to the subtraction of the H3 background signal from a g(2)(τ) measurement done on NV0 color centers.
Magnetic properties variation of two‐dimensional magnetophotonic crystals by light influence
Authors: Zvezdin Nikolay Y. , Prokaznikov Alexander V. , Afansyeva Darya E. , Paporkov Vladimir A.
Published: July 2013

Investigation of the magnetic properties of two‐dimensional magnetophotonic crystals (MPCs) based on silicon films covered by a Co layer several nanometers thick and a Cr layer several tens of nanometers thick indicated quasiperiodic variation of the magnetic properties of the system while interacting with electromagnetic radiation. Oscillations discovered of angular dependence of the transverse magneto‐optic Kerr effect are connected with resonant condition when a standing (stationary) wave is formed in a magnetic film. This wave activates the rotation of spins in the system and thereby changes the magnetic properties.
n‐ZnO/i‐InGaN/p‐GaN heterostructure for solar cell application
Authors: Nam Seung‐Yong , Choi Yong‐Seok , Song Young‐Ho , Jung Myoung‐Ho , Kang Chang Mo , Kong Duk‐Jo , Park Seong‐Ju , Lee Jeong‐Yong , Namkoong Gon , Lee Dong‐Seon
Published: July 2013

We report hybrid n‐ZnO/i‐InGaN/p‐GaN solar cells in which the n‐GaN layer of n‐GaN/i‐InGaN/p‐GaN solar cell was replaced with n‐type ZnO. In this study, inverted structures were used for hybrid ZnO/nitride solar cells where p‐type GaN was first grown on sapphire substrate, followed by i‐InGaN and n‐ZnO layers. The as‐fabricated device showed high series resistance and low energy conversion efficiency due to the formation of damaged p‐GaN region during dry etching. On the other hand, formation of microrods on the p‐GaN eased the removal of the damaged p‐GaN resulting in significantly lowered series resistance and enhanced energy conversion efficiency.

(a) n‐ZnO/i‐InGaN/p‐GaN solar cell structure without microrods, (b) n‐ZnO/i‐InGaN/p‐GaN solar cell structure with microrods, and (c) magnified image of the dashed box on (b).
Properties of the new electronic device material LaGdO3
Authors: Pavunny Shojan P. , Kumar Ashok , Misra Pankaj , Scott James F. , Katiyar Ram S.
Published: July 2013

The room temperature crystal structure of potential high‐kdielectric LaGdO3has been analyzed by X‐ray diffraction techniques and its structural evolution with temperature has been probed by Raman spectroscopy. Rietveld refinement of the ambient XRD data established the perfectly layered B‐type monoclinic crystal structure witha = 14.43 Å,b = 3.68 Å,c = 8.99 Å, andβ = 100.57° which is further validated by the 21 (14 Agand 7 Bg) Raman‐active vibrational modes with centro‐symmetric space grouporC2/m. Atomic positions, coordination numbers, inter‐ionic lengths, etc. were derived using Rietveld analysis. All prominent Bragg peaks were successfully indexed. Temperature dependent Raman spectra of LaGdO3from 80 to 1400 K were analyzed using the damped harmonic oscillator model. The softening and hardening of vibrational modes are reported. Above 900 K, disappearance of all high frequency modes (>600 cm−1) and merger of several mid frequency modes (between 200 and 500 cm−1) into two distinct modes was observed, a direct evidence of a possible structural phase transition from monoclinic to tetragonal/pseudocubic.
Biological Effects of the Aqueous Extract of Bridelia grandis Stem Bark on Normal and Neoplastic Human Cells: An In Vitro Preliminary Evaluation
Authors: Capelli Enrica , Ngueyem Tatiana , Lanza Enrica , Bertone Vittorio , Barni Sergio
Published: July 2013

The aim of the work is to investigate the effects of Bridelia grandis (Pierre ex Hutch) stem bark water extract on human HeLa cancer cells and normal monocytes treated in vitro, evaluating the morphological modifications with light and electron microscopy. The phytocomplex obtained from B. grandis caused a significant decrease in the mitotic index of both HeLa cancer cells and normal monocytes. In addition, a reduction of the typical aneuploid‐polyploid pattern has been observed in HeLa cells after treatment. Various alterations at fine structural level, both in neoplastic (HeLa cells) and normal (monocytes) cells have been observed. In particular, electron‐dense cells containing condensed mitochondria, autophagic vacuoles and dense spherical cytoplasmic inclusions have been observed. The results show that B. grandis water extracts have an antiproliferative effect on human cells, with a different effect on neoplastic and normal cells. The antiproliferative effect is accompanied by the appearance of various subcellular alterations. The morphological alterations observed are likely to represent the condition of ‘dark cell’ as a possible preliminary phase towards the autophagic and/or apoptotic cell death. Copyright © 2013 John Wiley & Sons, Ltd.
On the definition of a moist‐air potential vorticity
Authors: Marquet Pascal
Published: July 2013

A new potential vorticity is derived by using a specific entropy formulation expressed in terms of a moist‐air entropy potential temperature. The new formulation is compared with Ertel's version and with others based on virtual and equivalent potential temperatures. The new potential vorticity is subject to conservative properties ensured by the Second Law applied to the moist‐air material derivatives. It is shown that the upper tropospheric and stratospheric (dry) structures are nearly the same as those obtained with Ertel's component. Moreover, new structures are observed in the low troposphere, with negative values associated with moist frontal regions. The negative values are observed in the frontal regions where slantwise convection instabilities may take place, but they are smaller than those observed with the equivalent potential vorticity. The main purpose of the article is to diagnose the behaviour of the new potential vorticity from numerical output generated by the ARPEGE NWP model, with the help of isobaric charts and vertical cross‐sections. Two inversion methods are suggested. The first method could be based on the invertibility principle verified by the virtual potential vorticity, with a possibility to control and modify separately potential vorticity components in the (dry) upper and (moist) lower atmospheric levels. The other method may consist of an inversion process directly applied to the new moist‐air entropy potential vorticity, because the negative values and the solenoidal term are smaller than those observed with equivalent potential vorticity, as shown by numerical evaluations.
Cloud droplets in a bulk formulation and its application to buoyancy reversal instability
Authors: de Lozar A. , Mellado J. P.
Published: July 2013

Mixing processes at the boundary of clouds often include typical length‐scales of several metres. Such length‐scales are too large for current Lagrangian models but they are also poorly resolved by typical Eulerian‐based large‐eddy simulations. Here, a bulk formulation is introduced for direct numerical simulations. Two main assumptions sustain this approach: the continuum approximation and the liquid‐phase diffusion approximation. The formulation includes the small‐scale features that originate from microscopic droplet dynamics: sedimentation, finite‐time condensation/evaporation, inertial effects and the low diffusion of liquid droplets with respect to vapour. The methodology is applied to the study of the buoyancy reversal instability that occurs at the top of stratocumulus clouds as a consequence of evaporative cooling. The inclusion of sedimentation, low liquid‐phase diffusion and finite‐time evaporation have a negative impact on instability when compared with the equilibrium formulation. The combined effect of all these small‐scale features reduces mixing at the cloud top by at least 90%. This strong reduction is explained by a condensate‐free middle layer, which emerges when droplets leave the cloud interface due to sedimentation.
Quantification of docetaxel and its metabolites in human plasma by liquid chromatography/tandem mass spectrometry
Authors: Hendrikx J. J. M. A. , Dubbelman A. C. , Rosing H. , Schinkel A. H. , Schellens J. H. M. , Beijnen J. H.
Published: July 2013

RATIONALE

During drug development accurate quantification of metabolites in biological samples using mass spectrometry is often hampered by the lack of metabolites of chemically pure quality. However, quantification of metabolites can be useful for assessment and interpretation of (pre)clinical data. We now describe an approach to quantify docetaxel metabolites in human plasma by liquid chromatography/tandem mass spectrometry (LC/MS/MS) using docetaxel calibration standards.

METHODS

Metabolites (M1/M3, M2 and M4) were generated using microsomal incubations. Retention times of docetaxel and its metabolites were assessed using an LC/UV assay and peak identification was performed by LC/MSn. Samples containing isolated metabolites from human faeces were quantified by LC/UV and used as references for spiking human plasma samples. LC/MS/MS was applied to sensitively quantify docetaxel and its metabolites in human plasma using docetaxel calibration standards in a range of 0.25–500 ng/mL.

RESULTS

Because ionisation of docetaxel and its metabolites differed, correction factors were established to quantify the metabolites using docetaxel calibration samples. During method validation, accuracy and precision of the metabolites were within ±7.7% and ≤17.6%, respectively, and within ±14.3% and ≤10.1%, respectively, for docetaxel. Metabolites were found to be unstable in human plasma at ambient temperature. After storage up to 1 year at –20 °C, recovered metabolite concentrations were within ±25%.

CONCLUSIONS

Development and validation of an LC/MS/MS assay for the quantification of docetaxel and its metabolites M1/M3, M2 and M4 using docetaxel calibration standards is described. The same approach may be used for quantification of metabolites of other drugs by LC/MS/MS when chemically pure reference substances are unavailable. Copyright © 2013 John Wiley & Sons, Ltd.
Stochastic stability of semi‐Markovian jump systems with mode‐dependent delays
Authors: Li Fanbiao , Wu Ligang , Shi Peng
Published: July 2013

Semi‐Markovian jump systems, due to the relaxed conditions on the stochastic process, and its transition rates are time varying, can be used to describe a larger class of dynamical systems than conventional full Markovian jump systems. In this paper, the problem of stochastic stability for a class of semi‐Markovian systems with mode‐dependent time‐variant delays is investigated. By Lyapunov function approach, together with a piecewise analysis method, a sufficient condition is proposed to guarantee the stochastic stability of the underlying systems. As more time‐delay information is used, our results are much less conservative than some existing ones in literature. Finally, two examples are given to show the effectiveness and advantages of the proposed techniques. Copyright © 2013 John Wiley & Sons, Ltd.
Assessing geographic heterogeneity and variable importance in an air pollution data set
Authors: Stanley Young S. , Xia Jessie Q.
Published: July 2013

In this article, we examine data on the relationship between air quality and mortality in the United States using a published observational data set. Observational studies are complex and open to various interpretations. We show that there is geographic heterogeneity for the effect of air pollution on longevity. We also show that the relative importance of air pollution on longevity is much less than that of income or smoking. Most often authors do not address the relative importance of variables under consideration, choosing instead to concentrate on specific claims of significance. Yet good policy decisions require knowledge of the magnitude of relevant effects. Our analysis uses three methods for determining variable importance, showing how this puts predictor variables into a context that supports sound environmental policymaking. In particular, using both regression and recursive partitioning, we are able to confirm a spatial interaction with the air quality variable PM2.5; there is no significant association of PM2.5 with longevity in the west of the United States. We also determine the relative importance of PM2.5 in comparison to other predictor variables available in this data set. Our findings call into question the claim made by the original researchers. © 2013 Wiley Periodicals, Inc. Statistical Analysis and Data Mining, 2013
On assessing model fit for distribution‐free longitudinal models under missing data
Authors: Wu P. , Tu X.M. , Kowalski J.
Published: July 2013

The generalized estimating equation (GEE), a distribution‐free, or semi‐parametric, approach for modeling longitudinal data, is used in a wide range of behavioral, psychotherapy, pharmaceutical drug safety, and healthcare‐related research studies. Most popular methods for assessing model fit are based on the likelihood function for parametric models, rendering them inappropriate for distribution‐free GEE. One rare exception is a score statistic initially proposed by Tsiatis for logistic regression (1980) and later extended by Barnhart and Willamson to GEE (1998). Because GEE only provides valid inference under the missing completely at random assumption and missing values arising in most longitudinal studies do not follow such a restricted mechanism, this GEE‐based score test has very limited applications in practice. We propose extensions of this goodness‐of‐fit test to address missing data under the missing at random assumption, a more realistic model that applies to most studies in practice. We examine the performance of the proposed tests using simulated data and demonstrate the utilities of such tests with data from a real study on geriatric depression and associated medical comorbidities. Copyright © 2013 John Wiley & Sons, Ltd.
The Integration of Studio Cycling into a Worksite Stress Management Programme
Authors: Clark Matthew M. , Soyring Jason E. , Jenkins Sarah M. , Daniels Denise C. , Berkland Bridget E. , Werneburg Brooke L. , Hagen Philip T. , Lopez‐Jimenez Francisco , Warren Beth A. , Olsen Kerry D.
Published: July 2013

High stress is a prevalent problem in the worksite. To reduce stress, improve productivity, reduce absenteeism, and lower healthcare costs, many companies offer exercise classes or stress management programmes. Although physical activity is an important component of stress management, few worksites have integrated physical activity into their comprehensive stress reduction programmes. The purpose of this single‐arm pilot project was to examine the potential effectiveness of an integrated exercise (studio cycling) and cognitive–behavioural stress management programme. Eighty‐four adults, 75% female, mostly aged 40+ years, participated in an integrated 12‐week cycling studio and cognitive–behavioural stress management programme. Participants experienced a significant and clinically meaningful reduction on the Perceived Stress Scale (p < 0.01), rating of current stress level and confidence to manage stress at the programme's end and at a 1‐month follow‐up. Participants also reported having significantly improved overall health, improved nutritional habits, higher physical activity level, greater confidence in their ability to follow a healthy diet, higher spiritual well‐being, improved sleep, receiving more support for maintaining healthy living and improved quality of life at the completion of the 12‐week programme and 1‐month follow‐up. These findings provide further support for an integrated exercise and stress management programme. Copyright © 2013 John Wiley & Sons, Ltd.
The Relationship Between Stress and Body Satisfaction in Female and Male Adolescents
Authors: Murray Kristen , Rieger Elizabeth , Byrne Don
Published: July 2013

This study investigated the relationship between stress and body satisfaction in adolescence. A sample consisting of 515 adolescents aged 12–16 years completed a series of self‐report questionnaires assessing general and specific aspects of adolescent stress, body satisfaction and the psychological constructs of self‐esteem, depressive symptoms and body importance. Results revealed a significant association between higher body dissatisfaction and higher ratings of peer stress, lower self‐esteem and greater body importance for female and male adolescents. These findings suggest that adolescent stress relates to satisfaction with the body and that this stress is specifically focused on the peer environment for both genders during adolescence. This may have implications for intervention programmes aimed at improving body satisfaction, suggesting that the inclusion of stress management training in these programmes could specifically focus on difficulties within the peer domain. Copyright © 2013 John Wiley & Sons, Ltd.