bluuebunny/crossref_metadata_2025 huggingface dataset:
Acid‐Catalyzed Dehydration of Fructose into 5‐Hydroxymethylfurfural by Cellulose‐Derived Amorphous Carbon
Authors: Qi Xinhua , Guo Haixin , Li Luyang , Smith Richard L.
Published: August 2012

Carbonaceous solid (CS) catalysts with SO3H, COOH, and phenolic OH groups were prepared by incomplete hydrothermal carbonization of cellulose followed by either sulfonation with H2SO4 to give carbonaceous sulfonated solid (CSS) material or by both chemical activation with KOH and sulfonation to give activated carbonaceous sulfonated solid (a‐CSS) material. The obtained carbon products (CS, CSS, and a‐CSS) were amorphous; the CSS material had a small surface area (<0.5 m2 g−1) and a high SO3H group concentration (0.953 mmol g−1), whereas the a‐CSS material had a large surface area (514 m2 g−1) and a low SO3H group concentration (0.172 mmol g−1). The prepared materials were evaluated as catalysts for the dehydration of fructose to 5‐hydroxymethylfurfural (5‐HMF) in the ionic liquid 1‐butyl‐3‐methylimidazolium chloride ([BMIM][Cl]). Remarkably high 5‐HMF yields (83 %) could be obtained efficiently (80 °C and 10 min reaction time). CSS and a‐CSS catalysts had similar catalytic activities and efficiencies for the conversion of fructose to 5‐HMF in [BMIM][Cl]; this could be explained by the trade‐off between SO3H group concentration (high for CSS) and surface area (high for a‐CSS). The cellulose‐derived catalysts and ionic liquid exhibited constant activity for five successive recycles, and thus, the methods developed provide a renewable strategy for biomass conversion.
Hand preference for pointing and language development in toddlers
Authors: Vauclair Jacques , Cochet Hélène
Published: August 2012

The aim of this study was to investigate the relationship between hand preference for communicative gestures and language during development. Hand preference for pointing gestures and level of language were assessed in 46 toddlers between 12 and 30 months of age. Results showed a right‐hand preference for pointing and the use of a developmental quotient (DQ) for language revealed a significant correlation between the degree of hand preference and DQ for language in children with a quotient above 100. Thus, these children were more right‐handed for pointing gestures as DQ increased. These results highlight the close association between the development of hand preference for pointing and the speed of language development, suggesting a new direction for studies of language–gesture links in toddlers. © 2012 Wiley Periodicals, Inc. Dev Psychobiol 55: 757–765, 2013.
Variations in maternal care associated with differences in female rat reproductive behavior in a group‐mating environment
Authors: Prior Karen M. , Meaney Michael J. , Cameron Nicole M.
Published: August 2012

Maternal care influences the development of sexual behavior in pair mating rats, under laboratory conditions. This study examined the effect of variations in maternal care in a group‐mating condition. Groups of two low and two high licking/grooming (LG) female offspring mated with two males in a large pacing chamber for 36 hr. Sexual behaviors were scored for the first 15 vaginal–cervical stimulations (VCS) and the entire 36 hr. Low LG females spent more time mating, required more time to receive an intromission after entering the male compartment. They also received more ejaculations compared to high LG females during the first 15 VCS. This difference disappeared as mating continued. Males were more responsive to high than low females. No pregnancy rate difference was seen between the two female phenotypes, demonstrating that variation in maternal care received results in two mating strategies that are both reproductively successful under group‐mating conditions. © 2012 Wiley Periodicals, Inc. Dev Psychobiol 55: 838–848, 2013.
GAL4 enhancer traps that can be used to drive gene expression in developing Drosophila spermatocytes
Authors: Bunt Stephanie M. , Monk Adrian C. , Siddall Nicole A. , Johnston Neisha L. , Hime Gary R.
Published: August 2012

The Drosophila testis has proven to be a valuable model organ for investigation of germline stem cell (GSC) maintenance and differentiation as well as elucidation of the genetic programs that regulate differentiation of daughter spermatogonia. Development of germ cell specific GAL4 driver transgenes has facilitated investigation of gene function in GSCs and spermatogonia but specific GAL4 tools are not available for analysis of postmitotic spermatogonial differentiation into spermatocytes. We have screened publically available pGT1 strains, a GAL4‐encoding gene trap collection, to identify lines that can drive gene expression in late spermatogonia and early spermatocytes. While we were unable to identify any germline‐specific drivers, we did identify an insertion in the chiffon locus, which drove expression specifically in early spermatocytes within the germline along with the somatic cyst cells of the testis. genesis 50:914–920, 2012. © 2012 Wiley Periodicals, Inc.
Strain‐specific hyperkyphosis and megaesophagus in Add1 null mice
Authors: Robledo Raymond F. , Seburn Kevin L. , Nicholson Anthony , Peters Luanne L.
Published: August 2012

The three adducin proteins (α, β, and γ) share extensive sequence, structural, and functional homology. Heterodimers of α‐ and β‐adducin are vital components of the red cell membrane skeleton, which is required to maintain red cell elasticity and structural integrity. In addition to anemia, targeted deletion of the α‐adducin gene (Add1) reveals unexpected, strain‐dependentnon‐erythroid phenotypes. On an inbred 129 genetic background, Add1 null mice show abnormal inward curvature of the cervicothoracic spine with complete penetrance. More surprisingly, a subset of 129‐Add1 null mice develop severe megaesophagus, while examination of peripheral nerves reveals a reduced number of axons in 129‐Add1 null mice at four months of age. These unforeseen phenotypes, described here, reveal new functions for adducin and provide new models of mammalian disease. genesis 50:882–891, 2012. © 2012 Wiley Periodicals, Inc.
The decline and fall of the IGF‐I receptor
Authors: Baserga Renato
Published: August 2012

This review examines the effect of targeting the insulin‐like growth factor 1 receptor (IGF‐IR) in human cancers. The results are disappointing. The causes for the failure are discussed, as well as the possible use of the IGF‐IR as a secondary target. J. Cell. Physiol. 228: 675–679, 2013. © 2012 Wiley Periodicals, Inc.
Combining individual participant and aggregated data in a meta‐analysis with correlational studies
Authors: Pigott Terri , Williams Ryan , Polanin Joshua
Published: August 2012

This paper presents methods for combining individual participant data (IPD) with aggregated study level data (AD) in a meta‐analysis of correlational studies. Although medical researchers have employed IPD in a wide range of studies, only a single example exists in the social sciences. New policies at the National Science Foundation requiring grantees to submit data archiving plans may increase social scientists' access to individual level data that could be combined with traditional meta‐analysis. The methods presented here extend prior work on IPD to meta‐analyses using correlational studies. The examples presented illustrate the synthesis of publicly available national datasets in education with aggregated study data from a meta‐analysis examining the correlation of socioeconomic status measures and academic achievement. The major benefit of the inclusion of the individual level is that both within‐study and between‐study interactions among moderators of effect size can be estimated. Given the potential growth in data archives in the social sciences, we should see a corresponding increase in the ability to synthesize IPD and AD in a single meta‐analysis, leading to a more complete understanding of how within‐study and between‐study moderators relate to effect size. Copyright © 2012 John Wiley & Sons, Ltd.
Summer tree roost selection by Rafinesque's big‐eared bat
Authors: Clement Matthew J. , Castleberry Steven B.
Published: August 2012

Roost requirements of most North American forest bats are well‐documented, but questions remain regarding the ultimate mechanisms underlying roost selection. Hypotheses regarding roost selection include provision of a stable microclimate, space for large colonies, protection from predators, and proximity to foraging habitat, among others. Although several hypotheses have been proposed, specific mechanisms likely vary by species and geographic region. Rafinesque's big‐eared bat (Corynorhinus rafinesquii) commonly roosts in trees with large basal hollows in the Coastal Plain of the southeastern United States. Our objective was to weigh evidence for hypotheses regarding selection of diurnal summer roosts by Rafinesque's big‐eared bat at 8 study sites across the Coastal Plain of Georgia, USA. We used transect searches and radiotelemetry to locate roosts and measured 22 characteristics of trees, tree cavities, and surrounding vegetation at all occupied roosts and for randomly selected unoccupied trees. We evaluated 10 hypotheses using single‐season occupancy models and used Akaike's information criterion to select the most parsimonious models. We located 170 tree roosts containing approximately 870 bats for our analysis. The best supported model predicted bat presence from cavity size, interior wall texture, and number of entrances. Because large cavities allow bats to fly and smooth walls impede attacks by terrestrial predators, our results are consistent with the hypothesis that bats select roosts that allow them to evade predators. However, data on predation rates are needed for a conclusive determination. Because trees suitable as roosts for Rafinesque's big‐eared bat are rare in the landscape, protection of suitable forested wetland habitat is essential to provide current and long‐term roost tree availability. © 2012 The Wildlife Society.
SESAM‐free mode‐locked semiconductor disk laser
Authors: Kornaszewski L. , Maker G. , Malcolm G.P.A. , Butkus M. , Rafailov E.U. , Hamilton C.J.
Published: August 2012

Experimental demonstration of semiconductor saturable absorber‐free mode‐locked optically pumped semiconductor disk laser is presented. The origin of pulsed operation is attributed to the intensity dependent Kerr lens effect arising in the semiconductor gain medium. Achieved results represent a novel method to mode‐lock this type of laser opening new application opportunities. The laser worked stably in both hard and soft aperture configurations. No semiconductor saturable absorber was used in the laser cavity and the operation was self‐starting. The laser was mode‐locked at 210 MHz repetition rate with 1.5 W average output power and 930 fs pulse width at 985 nm. A record high 6.8 kW peak power was achieved. Measured data is presented along with a discussion of the Kerr lens effect in the cavity.
Tunable pH‐Sensitive Poly(β‐amino ester)s Synthesized from Primary Amines and Diacrylates for Intracellular Drug Delivery
Authors: Song Wantong , Tang Zhaohui , Li Mingqiang , Lv Shixian , Yu Haiyang , Ma Lili , Zhuang Xiuli , Huang Yubin , Chen Xuesi
Published: August 2012

The pH sensitivity of a series of PbAEs synthesized from primary amines and diacrylates is studied. By changing alkyl groups of the amine monomers, the pKb can be tuned across a broad range (from 3.5 to 7.2). Micelles formed from a PEG‐PbAE block copolymer retain the pH sensitivity of PbAE and can stably load hydrophobic molecules under neutral pH, while quickly dissociate and release their cargoes at pH ≈ 6.0. When the chemotherapy drug DOX is loaded, the micelles show efficient cell proliferation inhibition to HeLa cells and fast intracellular release. Thus, the primary‐amine‐based PbAEs are shown to be promising in the construction of intracellular targeting drug delivery systems.

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Polyfluorene Nanoparticles Coated with Folate‐Functionalized Triblock Copolymer: Effective Agents for Targeted Cell Imaging
Authors: Liu Li , Patra Abhijit , Scherf Ullrich , Kissel Thomas
Published: August 2012

An ultra‐bright fluorescence probe comprising conjugated polymer nanoparticles is developed for biological imaging. Highly blue fluorescent polyfluorene nanoparticles (PF‐NPs) stabilized by sodium dodecylsulfate with an average diameter of 100 nm are prepared by a miniemulsion technique. A folate‐conjugated cationic triblock copolymer is employed to coat negatively charged PF‐NPs via electrostatic interaction for specific cell imaging of folate receptor over‐expressing cancer cells. The coated PF‐NPs show a similar size and morphology to the pristine PF‐NPs, while the fluorescence intensity is enhanced. Such surface‐functionalized PF‐NPs are demonstrated to be suitable probes for efficient cell imaging of folate receptor over‐expressing KB cells by CLSM and flow cytometry.

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Thermo‐Switchable Antibacterial Activity
Authors: Mattheis Claudia , Zhang Yi , Agarwal Seema
Published: August 2012

A copolymer system of 2‐aminoethyl methacrylate and N‐isopropylacrylamide comprises novel properties: changes in conformation and hydrophilicity upon heating influence the antibacterial activity and result in a switchable biocidal effect. The copolymers are characterized via NMR, MALDI‐ToF MS, phase transition behavior, and antibacterial tests with E. coli or B. subtilis. MIC and MBC are determined using standard dilution methods, temperature‐dependence via incubation at different temperatures and cytotoxicity by MTT tests. The copolymers exhibit lower MIC in globule than coil conformation, crosslinking on cotton results in non‐leaching materials with better antibacterial activity above than below the phase‐transition point.

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Functionalized Nanoporous Thin Films From Blends of Block Copolymers and Homopolymers Interacting via Hydrogen Bonding
Authors: Gamys Cé Guinto , Vlad Alexandru , Bertrand Olivier , Gohy Jean‐François
Published: August 2012

Blends of poly(acrylic acid)‐block‐polystyrene (PAA‐b‐PS) copolymers and poly(ethylene oxide) (PEO) homopolymers in which PAA and PEO interact via hydrogen bonds were used as precursors of nanoporous PS thin films with cavities decorated by PAA blocks. The presence of free carboxylic acid groups inside the pores was evidenced by fluorescence spectroscopy after reacting them with a diazomethane functionalized fluorescent dye. These nanoporous thin films were then used as templates for the preparation of dense arrays of silica nanodots.
New Polymer Materials for Steel/Polymer/Steel Laminates in Automotive Applications
Authors: Avril Florence , Rahmé Roland , Doux Marjolaine , Verchere Didier , Sage Daniel , Cassagnau Philippe
Published: August 2012

The present works aims to develop multi‐materials such as steel/polymer/steel hybrid system for weight savings in automotive industries. This laminate must be compatible with processing on the industrial line (steel/polymer lamination under 200 °C) and the structure must be flow‐resistant during the paint process curing (200 °C for 30 min). Consequently, a yield stress polymer system based on compatibilized PA11/copolymer of ethylene and octene blends has been developed. The yield stress property (for T > 200 °C) depends on the phase concentration and compatibilization strategy. It is observed that an annealing process (heating treatment for 1 h at 200 °C), simulating the painting process, provides a strong benefit for the polymer/steel properties after aging under humidity conditions.

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Design and Synthesis of Poly(butyl acrylate) Networks through RAFT Polymerization with Crosslinking for Controlled‐Release Applications
Authors: Huang Jianmin , Wang Wen‐Jun , Li Bo‐Geng , Zhu Shiping
Published: August 2012

An effective approach is presented for designing and tailoring diffusion‐controlled systems for targeted release rate profiles. The diffusion‐controlled system consists of PBA networks with precisely controlled crosslink densities via RAFT copolymerization of BA with ethylene glycol dimethacrylate, which gives a desired diffusivity. One‐dimensional releases in the crosslinked PBA matrix (CPM) slabs are evaluated with a hydrophobic dye. Fick's second law is used to model the transient mass transfers in the CPMs with a mixed Newton‐Tikhonov regularization method for determination of their diffusion coefficients. A two‐layer CPM (CPM‐2) with controlled crosslink densities is constructed. The dye release results from the CPM‐2 agreed well with theoretical predictions.

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Caffeine and risk of Parkinson's disease in a large cohort of men and women
Authors: Palacios Natalia , Gao Xiang , McCullough Marjorie L. , Schwarzschild Michael A. , Shah Roma , Gapstur Susan , Ascherio Alberto
Published: August 2012

Caffeine consumption has been associated with a reduced risk of Parkinson's disease (PD). The association is strong and consistent in men, but uncertain in women, possibly because of an interaction with hormone replacement therapy (HRT). We sought to confirm these findings using data on PD incidence in the Cancer Prevention Study II Nutrition Cohort (CPS II–Nutrition), a large, prospective study of men and women. We conducted a prospective study of caffeine intake and risk of PD within the CPS II Nutrition Cohort. Intakes of coffee and other sources of caffeine were assessed at baseline. Incident cases of PD (n = 317; 197 men and 120 women) were confirmed by treating physicians and medical record review. Relative risks (RRs) were estimated using proportional hazards models, adjusting for age, smoking, and alcohol consumption. After adjustment for age, smoking, and alcohol intake, high caffeine consumption was associated with a reduced risk of PD. The RR comparing the 5th to the 1st quintile of caffeine intake was 0.43 (95% confidence interval [CI]: 0.26, 0.71; P trend = <0.002) in men, and 0.61 (95% CI: 0.34, 1.09; P trend = 0.05) in women. Among women, this association was stronger among never users of HRT (RR = 0.32) than among ever users (RR = 0.81; P interaction = 0.15). Consumption of decaffeinated coffee was not associated with PD risk. Findings from this large, prospective study of men and women are consistent with a protective effect of caffeine intake on PD incidence, with an attenuating influence of HRT in women. © 2012 Movement Disorder Society
Short latency activation of cortex by clinically effective thalamic brain stimulation for tremor
Authors: Walker Harrison C. , Huang He , Gonzalez Christopher L. , Bryant James E. , Killen Jeffrey , Knowlton Robert C. , Montgomery Erwin B. , Cutter Gary C. , Yildirim Abidin , Guthrie Bart L. , Watts Ray L.
Published: August 2012

Deep brain stimulation (DBS) relieves disabling symptoms of neurologic and psychiatric diseases when medical treatments fail, yet its therapeutic mechanism is unknown. We hypothesized that ventral intermediate (VIM) nucleus stimulation for essential tremor activates the cortex at short latencies, and that this potential is related to the suppression of tremor in the contralateral arm. We measured cortical activity with electroencephalography in 5 subjects (seven brain hemispheres) across a range of stimulator settings, and reversal of the anode and cathode electrode contacts minimized the stimulus artifact, allowing visualization of brain activity. Regression quantified the relationship between stimulation parameters and both the peak of the short latency potential and tremor suppression. Stimulation generated a polyphasic event‐related potential in the ipsilateral sensorimotor cortex, with peaks at discrete latencies beginning less than 1 ms after stimulus onset (mean latencies 0.9 ± 0.2, 5.6 ± 0.7, and 13.9 ± 1.4 ms, denoted R1, R2, and R3, respectively). R1 showed more fixed timing than the subsequent peaks in the response (P < 0.0001, Levene's test), and R1 amplitude and frequency were both closely associated with tremor suppression (P < 0.0001, respectively). These findings demonstrate that effective VIM thalamic stimulation for essential tremor activates the cerebral cortex at approximately 1 ms after the stimulus pulse. The association between this short latency potential and tremor suppression suggests that DBS may improve tremor by synchronizing the precise timing of discharges in nearby axons and, by extension, the distributed motor network to the stimulation frequency or one of its subharmonics. © 2012 Movement Disorder Society
Kalman filter techniques for accelerated Cartesian dynamic cardiac imaging
Authors: Feng Xue , Salerno Michael , Kramer Christopher M. , Meyer Craig H.
Published: August 2012

In dynamic MRI, spatial and temporal parallel imaging can be exploited to reduce scan time. Real‐time reconstruction enables immediate visualization during the scan. Commonly used view‐sharing techniques suffer from limited temporal resolution, and many of the more advanced reconstruction methods are either retrospective, time‐consuming, or both. A Kalman filter model capable of real‐time reconstruction can be used to increase the spatial and temporal resolution in dynamic MRI reconstruction. The original study describing the use of the Kalman filter in dynamic MRI was limited to non‐Cartesian trajectories because of a limitation intrinsic to the dynamic model used in that study. Here the limitation is overcome, and the model is applied to the more commonly used Cartesian trajectory with fast reconstruction. Furthermore, a combination of the Kalman filter model with Cartesian parallel imaging is presented to further increase the spatial and temporal resolution and signal‐to‐noise ratio. Simulations and experiments were conducted to demonstrate that the Kalman filter model can increase the temporal resolution of the image series compared with view‐sharing techniques and decrease the spatial aliasing compared with TGRAPPA. The method requires relatively little computation, and thus is suitable for real‐time reconstruction. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
A robust genomic signature for the detection of colorectal cancer patients with microsatellite instability phenotype and high mutation frequency
Authors: Tian Sun , Roepman Paul , Popovici Vlad , Michaut Magali , Majewski Ian , Salazar Ramon , Santos Cristina , Rosenberg Robert , Nitsche Ulrich , Mesker Wilma E , Bruin Sjoerd , Tejpar Sabine , Delorenzi Mauro , Bernards Rene , Simon Iris
Published: August 2012

Microsatellite instability (MSI) occurs in 10–20% of colorectal tumours and is associated with good prognosis. Here we describe the development and validation of a genomic signature that identifies colorectal cancer patients with MSI caused by DNA mismatch repair deficiency with high accuracy. Microsatellite status for 276 stage II and III colorectal tumours has been determined. Full‐genome expression data was used to identify genes that correlate with MSI status. A subset of these samples (n = 73) had sequencing data for 615 genes available. An MSI gene signature of 64 genes was developed and validated in two independent validation sets: the first consisting of frozen samples from 132 stage II patients; and the second consisting of FFPE samples from the PETACC‐3 trial (n = 625). The 64‐gene MSI signature identified MSI patients in the first validation set with a sensitivity of 90.3% and an overall accuracy of 84.8%, with an AUC of 0.942 (95% CI, 0.888–0.975). In the second validation, the signature also showed excellent performance, with a sensitivity 94.3% and an overall accuracy of 90.6%, with an AUC of 0.965 (95% CI, 0.943–0.988). Besides correct identification of MSI patients, the gene signature identified a group of MSI‐like patients that were MSS by standard assessment but MSI by signature assessment. The MSI‐signature could be linked to a deficient MMR phenotype, as both MSI and MSI‐like patients showed a high mutation frequency (8.2% and 6.4% of 615 genes assayed, respectively) as compared to patients classified as MSS (1.6% mutation frequency). The MSI signature showed prognostic power in stage II patients (n = 215) with a hazard ratio of 0.252 (p = 0.0145). Patients with an MSI‐like phenotype had also an improved survival when compared to MSS patients. The MSI signature was translated to a diagnostic microarray and technically and clinically validated in FFPE and frozen samples. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Protocadherin 17 acts as a tumour suppressor inducing tumour cell apoptosis and autophagy, and is frequently methylated in gastric and colorectal cancers
Authors: Hu Xiaotong , Sui Xinbing , Li Lili , Huang Xuefeng , Rong Rong , Su Xianwei , Shi Qinglan , Mo Lijuan , Shu Xingsheng , Kuang Yeye , Tao Qian , He Chao
Published: August 2012

Gastric and colorectal cancers are among the most common cancers worldwide and cause serious cancer mortality. Both epigenetic and genetic disruptions of tumour suppressor genes (TSGs) are frequently involved in their pathogenesis. Here, we studied the epigenetic and genetic alterations of a novel TSG–PCDH17 and its functions in the pathogenesis of these tumours. We found that PCDH17 was frequently silenced and methylated in almost all gastric and colorectal tumour cell lines as well as in ∼95% of primary tumours, but not in normal gastric and colonic mucosa. Moreover, its deletion was detected in only 18% of gastric and 12% of colorectal cancer tissues, suggesting that epigenetic and genetic inactivation of PCDH17 are both involved in gastric and colorectal tumourigenesis. PCDH17 protein expression was significantly correlated with low tumour stage and less lymph node metastasis of gastric and colorectal cancer patients, indicating its potential as a tumour marker. Restoring PCDH17 expression inhibited tumour cell growth in vitro and in vivo through promoting apoptosis, as evidenced by increased TUNEL staining and caspase‐3 activation. Furthermore, PCDH17‐induced autophagy, along with increased numbers of autophagic vacuoles and up‐regulated autophagic proteins Atg‐5, Atg‐12 and LC3B II. Thus, PCDH17 acts as a tumour suppressor, exerting its anti‐proliferative activity through inducing apoptosis and autophagy, and is frequently silenced in gastric and colorectal cancers. PCDH17 methylation is a tumour‐specific event that could serve as an epigenetic biomarker for these tumours.
Developmental stage‐specific contribution of LGR5+ cells to basal and luminal epithelial lineages in the postnatal mammary gland
Authors: de Visser Karin E , Ciampricotti Metamia , Michalak Ewa M , Tan David Wei‐Min , Speksnijder Ewoud N , Hau Cheei‐Sing , Clevers Hans , Barker Nick , Jonkers Jos
Published: August 2012

The leucine‐rich repeat‐containing heterotrimeric guanine nucleotide‐binding protein‐coupled receptor 5 (LGR5) has been identified as a marker of cycling stem cells in several epithelial tissues, including small intestine, colon, stomach and hair follicle. To investigate whether LGR5 also marks mammary epithelial stem cells, we performed in situ lineage‐tracing studies and mammary gland reconstitutions with LGR5‐expressing mammary epithelial cells. Interestingly, the LGR5 progeny population in mammary epithelium switches from the luminal to the myoepithelial compartment during the first 12 days of postnatal development, likely reflecting local changes in Wnt signalling. Together, our findings point to a stage‐specific contribution of LGR5‐expressing cells to luminal and basal epithelial lineages during postnatal mammary gland development. Copyright © 2012 Pathological Society of Great Britain and Ireland.
Stem cell research points the way to the cell of origin for intracranial germ cell tumours
Authors: Tan Chris , Scotting Paul J
Published: August 2012

Germ cell tumours found in the brain (intracranial GCTs) are a very unusual class of tumour for two reasons. First, they include a very diverse range of histological subtypes classified together due to their proposed common cell of origin. Second, this proposed cell of origin, the germ cell progenitor, would not normally be found in the tissue where these tumours arise. This is in contrast to all other primary brain tumours, in which the cell of origin is believed to be a brain cell. Indeed, no other class of primary cancer arises from a cell from a distant organ. This theory for the origins of intracranial GCTs has been in place for many decades, but recent data arising from studies of induced pluripotency for regenerative medicine raise serious questions about this dogma. Here we review the cellular origins of intracranial GCTs in the light of these new data and reanalyse the existing data on the biology of this unusual class of tumours. Together, these considerations lead us to conclude that the evidence now falls in favour of a model in which these tumours arise from the transformation of endogenous brain cells. This theory should inform future studies of the aetiology of these tumours and so lead the way to animal models in which to study their development and potential biological therapeutics. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Electro‐optical study of a ×1024 concentrator photovoltaic system
Authors: Pereira Alexandre , Dargent Loïc , Lorin Géraldine , Schwartz Wilfrid , Baffie Thierry , Mangeant Christophe , Mariotto Mathieu , de Salins Jean‐Edouard , Vives Guillaume
Published: August 2012

Concentrator photovoltaic (CPV) systems are one of the most promising technologies for future energy supply. Several studies reported the interest of using a Fresnel lens coupled with a secondary optical element in such a system. For high concentration factor, the optimization of the optical configuration plays a key role regarding electrical performances. On the other hand, the thermal management of the solar cell is also critical to ensure a better module efficiency. This paper presents a study of a ×1024 CPV system performances and a methodology for estimating the optical chain efficiency, the cell temperature impact and the alignment requirements. Module efficiencies were then measured as a function of the cell temperature and correlated to optical performances through current‐tension characterizations under real solar illumination conditions and the estimation of the power density received by the solar cell. The system yield was up to 27% for a cell temperature around 30 °C, confirming that high concentration ratio should be of great interest in the near future. A 1D model was also developed in order to quantify the possible improvements of this CPV system. Using a solar cell with an efficiency of 36.7% at ×600, we then demonstrated that the ×1024 CPV system could reach up to 30% in standard test conditions. Copyright © 2012 John Wiley & Sons, Ltd.
Gene expression analysis in prostate cancer: The importance of the endogenous control
Authors: Vajda Alice , Marignol Laure , Barrett Ciara , Madden Stephen F. , Lynch Thomas H. , Hollywood Donal , Perry Antoinette S.
Published: August 2012

BACKGROUND

Aberrant gene expression is a hallmark of cancer. Quantitative reverse‐transcription PCR (qRT‐PCR) is the gold‐standard for quantifying gene expression, and commonly employs a house‐keeping gene (HKG) as an endogenous control to normalize results; the choice of which is critical for accurate data interpretation. Many factors, including sample type, pathological state, and oxygen levels influence gene expression including putative HKGs. The aim of this study was to determine the suitability of commonly used HKGs for qRT‐PCR in prostate cancer.

METHODS

Prostate cancer (LNCaP, 22Rv1, PC3, and DU145) and normal (PWR1E and RWPE1) cell lines were cultured in air and hypoxia. The performance of 16 HKGs was assessed using Normfinder and coefficient of variation. In silico promoter analysis was performed to identify putative hypoxia response elements (HREs). The impact of the endogenous control on expression levels of HIF1A and GSTP1 was investigated by qRT‐PCR in cell lines and tissue specimens respectively.

RESULTS

Hypoxia altered expression of several HKGs: IPO8, B2M, and PGK1. The most stably expressed HKGs were ACTB, PPIA, and UBC. Both UBC and ACTB showed constitutive expression of HIF1A in air and hypoxia, while PGK1 falsely implied a sixfold hypoxia‐induced down‐regulation. In prostate tumors, UBC and PGK1 both revealed down‐regulation of GSTP1 relative to matched benign, whereas ACTB showed variability.

CONCLUSIONS

This study demonstrates that no universal endogenous control exists for gene expression studies, even within one disease type. It highlights the importance of validating expression of intended HKGs between different sample types and environmental exposures. Prostate 73: 382–390, 2013. © 2012 Wiley Periodicals, Inc.
Deep level studies in high‐temperature annealed silicon wafers for layer transfer in thin‐film solar cells
Authors: Simoen Eddy , Depauw Valerie , Gordon Ivan , Poortmans Jef
Published: August 2012

Deep‐level transient spectroscopy (DLTS) has been applied to high‐temperature annealed n‐ and p‐type Si wafers. The aim is to identify the deep levels responsible for the observed minority carrier lifetime degradation after thin‐film transfer to a glass substrate. Anneals have been performed at 1150 °C in H2 or Ar. Care has been taken to avoid radiation defect formation during the fabrication of the Al Schottky barriers used for DLTS. It is shown that besides a change in the carrier doping density and profile, an annealing‐induced electron trap at 0.43 eV below the conduction band edge can be found, which is related to a vacancy–impurity complex.
UV‐illuminated dielectrophoresis by two‐dimensional electron gas (2DEG) in AlGaN/GaN heterojunction
Authors: Fu Junxue , Luo Yuan , Yobas Levent , Chen Kevin J.
Published: August 2012

Dielectrophoresis (DEP) induced by activating a patterned two‐dimensional electron gas (2DEG) at the interface of compound semiconductor AlGaN/GaN heterojunction has been demonstrated for the first time in our previous work. Briefly, with a peak voltage of ±10 V and a frequency from 100 kHz to 1 MHz, characteristics of both positive and negative DEP have been observed successfully manipulating 2 µm polystyrene microspheres in a drop of deionized (DI) water (pH ∼ 7 and conductivity 1 × 10−4 S m−1) over castellated 2DEG electrodes separated by critical dimensions 50 and 150 µm. This study reports a peculiar observation encountered when performing the DEP experiments under ultraviolet (UV) radiation: The microspheres have been repelled from the 2DEG electrodes yet remained on the surface during pDEP and then levitated upon switching to nDEP. This behavior is not observed in DEP with conventional microelectrodes and explained here by the UV‐induced electron–hole generation and the subsequent charge redistribution in the AlGaN/GaN heterostructure.
Structural and optical properties of crystalline silicon thin films deposited on porous alumina
Authors: Ktifa S. , Ghrib M. , Saadallah F. , Yacoubi N.
Published: August 2012

The goal of this work is to investigate the influence of the anodization current on the optical properties of porous alumina layer, on which crystalline silicon films are deposited by a PECVD technique. Porous alumina layers were grown by a simple electrochemical anodization method, varying the anodizing voltage between 200 to 400 mV.

The structural properties of the Si/Al2O3 films were studied by using Raman spectroscopy and XRD. Photothermal deflection spectroscopy (PDS) is used to determine the gap energy and the optical absorption spectrum by comparing the experimental amplitude of the photothermal signal to the corresponding theoretical one (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A detailed investigation on the failure mechanisms for IGBTs under successive short‐circuit conditions
Authors: Benbahouche Ly. , Merabet A. , Zegadi A.
Published: August 2012

The increasing demand in terms of device performance and reliability requires continuous developments of power semiconductors that operate under hard switching conditions SOA (Safe Operating Area). The aim of this paper to enable a better understanding of the main problems that are associated with successive short circuit failure modes like (latch up and second breakdown) and also to clarify the correlation with respect to the circuit elements. It investigates the temperature impact of successive short‐circuit delay time effects on the failure mechanisms evolutions and to evaluates the feasibility and issues of IGBT under successive short‐circuit conditions. The device behaviour can predicted at critical operations such as its latch up during a turn off short circuit condition or if there is an observable aging effect. It is shown that when applied to IXGH‐IGBT at its worst short circuit condition (successive short circuit), this one can work securely without affecting the normal system operation at higher temperatures. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
DFT study of the effect of hydrostatic pressure on formation and migration enthalpies of intrinsic point defects in single crystal Si
Authors: Sueoka Koji , Kamiyama Eiji , Kariyazaki Hiroaki , Vanhellemont Jan
Published: August 2012

The dependence of the formation enthalpy (Hf) of the self‐interstitial I and the vacancy V on the hydrostatic pressure P was obtained by calculating the formation energy (Ef) and the relaxation volume (vf). The dependence of the migration enthalpy (Hm) of I and V on the pressure P was also obtained by calculating the change of Hf during the migration. Density functional theory calculations were used with 216‐atom supercells and with special attention for the convergence of the calculations. The neutral I and V are found to have quasi constant formation energies EfI and EfV for pressures between – 1 GPa to 1 GPa. For the relaxation volume, vfI is almost constant while vfV decreases with increasing pressure P. The formation and migration enthalpies HfI and HmI, respectively, at the [110] dumbbell site are given by HfI = 3.425 – 0.055×P (eV) and HmI = 0.981 – 0.039×P (eV) with hydrostatic pressure P given in GPa. The HfV and HmV dependencies on P are given by HfV =3.543 – 0.024×P2– 0.009×P (eV) and HmV = 0.249 + 0.005×P2 – 0.030×P (eV). These results indicate that hydrostatic pressure leads to a slight increase of the equilibrium concentration and diffusion of vacancies but this increase is considerably smaller than that of self‐interstitials (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Defect generation by argon implantation: microscopy characterization and electrical properties
Authors: Mica Isabella , Polignano Maria Luisa , Codegoni Davide , Mauri Aurelio , Soncini Valter
Published: August 2012

In this work defects generated by argon implantation were studied both by Transmission Electron Microscopy (TEM) inspections and by measurements of the defect electrical activity at the oxide‐silicon interface and in the bulk. TEM analyses showed defects close to the surface for argon doses equal or larger than 1013cm‐2, and stacking faults in the sample implanted with 1015 cm‐2 dose. The maximum defect depth was about 50 nm. The generation lifetime was heavily degraded even with the lowest argon dose. Besides, positive charge and a relevant population of interface states were found to be related to argon implantation. In addition, DLTS revealed four deep levels starting with the samples implanted with 1013cm‐2 argon dose. These levels evolve with increasing the argon dose and are located much deeper than the defects revealed by TEM, i.e. down to a few micron depth. The dependence of the signal amplitude on the filling pulse width was analyzed, and showed that all the observed levels are related to extended defects. Kinetic Monte Carlo simulations of the implantation and annealing process indicate that argon atoms interact with implantation‐induced defects and enhance the formation of extended defects. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth and characterization of silicon nanocrystallites embedded in amorphous silicon carbon matrix by PECVD
Authors: Coscia U. , Ambrosone G. , Basa D. K. , Rigato V. , Ballarini M. , Virga A. , Ferrero S. , Mercaldo L. V.
Published: August 2012

Nanostructured silicon carbon films, composed of silicon nanocrystals embedded in hydrogenated amorphous silicon carbon matrix, have been prepared by plasma enhanced chemical vapor deposition technique using silane and methane gas mixture diluted in hydrogen. The composition, structure and surface morphology of the films have been investigated by nuclear techniques, Raman, Fourier transform infrared spectroscopy and atomic force microscopy. The study has demonstrated that the nanostructured silicon carbon films can be deposited at low temperature (250 °C) by varying rf power and the crystallinity degree of silicon is quite uniform along the growth direction. Further, it has established that with increase in rf power crystalline volume fraction decreases while carbon content increases in the films (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phosphorous doping of superlattice silicon quantum dots in silicon dioxide
Authors: Simonds Brian J. , Perez‐Würfl Ivan , So Yong‐Heng , Wan Alan S. , McMurray Sarah , Taylor P. Craig
Published: August 2012

Here we investigate the effects of phosphorous (P) doping of silicon quantum dots in a silicon dioxide superlattice structure. The doping occurs by diffusion of P during high‐temperature annealing from P‐rich silicon dioxide regions to directly adjacent layers containing the quantum dots embedded in oxide. Secondary ion mass spectroscopy (SIMS) is used to clearly show that after annealing, the P preferentially resides in the regions containing the dots. Once in these regions, electron paramagnetic resonance (EPR) shows that a relatively small fraction of this P is used to passivate dangling bonds on the surfaces of the quantum dots. Additionally, EPR shows no evidence that any of the P is located in the interior of the dot. Using calibrated SIMS values along with the EPR evidence allows us to conclude that the P is concentrated in the area surrounding the dots in a non‐paramagnetic configuration. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Silicon processing for photovoltaics based on incoherent radiation power
Authors: Serra João M.
Published: August 2012

It is well known that impurity contamination is a very important factor in silicon processing. Contamination arises from crucibles or graphite susceptors during crystal growth, from the use of fibers or dies as in the case of String ribbon or EFG technologies respectively. Furthermore, every hot part in a crystal growth system will contribute to increase impurity contamination. Optical processing using halogen lamps provides clean method, with available fast rise and fall ramps, cold wall furnaces, with great flexibility in many situations related to materials processing and in particular in photovoltaics. Optical power provided by halogen lamps is very cheap, which is an important aspect for an industry that needs to reduce process costs. Techniques based in lamp power radiation have been in use in our laboratory at the University of Lisbon for many years. Several examples of the use of such optical techniques are presented, illustrating its application to silicon ribbon growth, kerfless techniques and on its successful application for photovoltaics in a gas‐to‐wafer path, bypassing both the Siemens and the traditional wafering steps. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
New advances in metallurgical solar grade silicon based on recent Norwegian research activities
Authors: Øvrelid Eivind , Tangstad Merete , Tranell Gabriella , Lohne Otto , Ceccaroli Bruno
Published: August 2012

Among the new routes for the production of solar grade silicon, the metallurgical refining leading to upgraded metallurgical grade (UMG) silicon emerge as serious alternatives to replace the feedstock produced by the Siemens process (commonly called polysilicon). Most of these new alternative processes generally consist of a sequence of purification steps. The most effective and frequently used among these refining steps will be described. Some recent results based on research studies carried out in Norway will be presented with more details. The intention is to give an overview and an understanding of these emerging processes and provide some tools to optimize and further develop new cost efficient processes for production of solar grade silicon (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Surface‐modulated magnetization of magnetite microspheres
Authors: Ma Ji , Chen Kezheng
Published: August 2012

Functional coatings of magnetite particles always reduce their magnetic response and greatly limit their biological in‐vivo applications. In this Letter, an effective solution was proposed by inducing large lattice strain in magnetite microspheres with silver. Their saturation magnetization was found to be larger than that of their parent magnetite spheres at 300 K. Also, an increment of saturation magnetization with temperature was observed, which has not been reported in ferrimagnetic systems before. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A survey on unsupervised outlier detection in high‐dimensional numerical data
Authors: Zimek Arthur , Schubert Erich , Kriegel Hans‐Peter
Published: August 2012

High‐dimensional data in Euclidean space pose special challenges to data mining algorithms. These challenges are often indiscriminately subsumed under the term ‘curse of dimensionality’, more concrete aspects being the so‐called ‘distance concentration effect’, the presence of irrelevant attributes concealing relevant information, or simply efficiency issues. In about just the last few years, the task of unsupervised outlier detection has found new specialized solutions for tackling high‐dimensional data in Euclidean space. These approaches fall under mainly two categories, namely considering or not considering subspaces (subsets of attributes) for the definition of outliers. The former are specifically addressing the presence of irrelevant attributes, the latter do consider the presence of irrelevant attributes implicitly at best but are more concerned with general issues of efficiency and effectiveness. Nevertheless, both types of specialized outlier detection algorithms tackle challenges specific to high‐dimensional data. In this survey article, we discuss some important aspects of the ‘curse of dimensionality’ in detail and survey specialized algorithms for outlier detection from both categories. © 2012 Wiley Periodicals, Inc. Statistical Analysis and Data Mining, 2012
Cornering new physics in b → s transitions
Authors: Altmannshofer Wolfgang , Straub David M.
Published: August 2012

Abstract

We derive constraints on Wilson coefficients of dimension-six effective operators probing the b → s transition, using recent improved measurements of the rare decays B
s → μ
+
μ
−, B → Kμ
+
μ
− and B → K

*

μ
+
μ
− and including all relevant observables in inclusive and exclusive decays. We consider operators present in the SM as well as their chirality-flipped counterparts and scalar operators. We find good agreement with the SM expectations. Compared to the situation before winter 2012, we find significantly more stringent constraints on the chirality-flipped coefficients due to complementary constraints from B → Kμ
+
μ
− and B → K

*

μ
+
μ
− and due to the LHCb measurement of the angular observable S
3 in the latter decay. We also list the full set of observables sensitive to new physics in the low recoil region of B → K

*

μ
+
μ
−.