bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatial and temporal patterns of snow accumulation and aerial ablation across the McMurdo Dry Valleys, Antarctica
Authors: Eveland Jeffery , Gooseff Michael N. , Lampkin Derrick J. , Barrett J. E. , Takacs‐Vesbach Cristina
Published: May 2012

Snow in the McMurdo Dry Valleys is a potential source of moisture for subnivian soils in a cold desert ecosystem. In a water‐limited environment, enhanced soil moisture is expected to provide more favourable conditions for subnivian soil communities. In addition, snow cover insulates the underlying soil from air temperature extremes. Quantifying the spatial and temporal patterns of seasonal snow accumulation and ablation is necessary to understand these dynamics. Repeat high‐resolution imagery acquired for the 2009–2010 austral summer was used to map the seasonal distribution of snow across Taylor and Wright valleys, Southern Victorialand, Antarctica. An edge detection algorithm was used to perform an object‐based classification of snow‐covered area. Coupled with topographic parameters obtained from a 30‐m digital elevation model, unique distribution patterns were characterized for five regions within the neighbouring valleys. Time lapses of snow distribution in each region provide insight into spatially variable aerial ablation rates (change in area of landscape covered by snow) across the region. A strong coastal to interior gradient of decreasing snow‐covered area was evident for both Taylor and Wright valleys. The surrounding regions of Lake Fryxell, Lake Hoare, Lake Bonney, Lake Brownworth, and Lake Vanda exhibited losses of snow‐covered area of 9.61 km2 (−93%), 1.63 km2 (−72%), 1.07 km2 (−97%), 2.60 km2 (−82%), and 0.25 km2 (−96%), respectively, as measured from peak accumulation in October to mid‐January. Differences in aerial ablation rates within and across local regions suggest that both topographic variation and regional microclimates influence the ablation of seasonal snow cover. Copyright © 2012 John Wiley & Sons, Ltd.
Response of snow processes to climate change: spatial variability in a small basin in the Spanish Pyrenees
Authors: López‐Moreno J. I. , Pomeroy J. W , Revuelto J. , Vicente‐Serrano S. M.
Published: May 2012

In this study, the Cold Regions Hydrological Modelling platform was used to create an alpine snow model including wind redistribution of snow and energy balance snowmelt to simulate the snowpack over the period 1996–2009 in a small (33 ha) snow‐dominated basin in the Spanish Pyrenees. The basin was divided into three hydrological response units (HRUs), based on contrasting physiographic and aerodynamic characteristics. A sensitivity analysis was conducted to calculate the snow water equivalent regime for various combinations of temperature and precipitation that differed from observed conditions. The results show that there was large inter‐annual variability in the snowpack in this region of the Pyrenees because of its marked sensitivity to climatic conditions. Although the basin is small and quite homogeneous, snowpack seasonality and inter‐annual evolution of the snowpack varied in each HRU. Snow accumulation change in relation to temperature change was approximately 20% for every 1 °C, and the duration of the snowpack was reduced by 20–30 days per °C. Melting rates decreased with increased temperature, and wind redistribution of snow was higher with decreased temperature. The magnitude and sign of changes in precipitation may markedly affect the response of the snowpack to changes in temperature. There was a non‐linear response of snow to individual and combined changes in temperature and precipitation, with respect to both the magnitude and sign of the change. This was a consequence of the complex interactions among climate, topography and blowing snow in the study basin. Copyright © 2012 John Wiley & Sons, Ltd.
E2F1‐dependent pathways are involved in amonafide analogue 7‐d‐induced DNA damage, G2/M arrest, and apoptosis in p53‐deficient K562 cells
Authors: Li Yiquan , Shao Jin , Shen Ke , Xu Yufang , Liu Jianwen , Qian Xuhong
Published: May 2012

The E2F1 gene well known is its pivotal role in regulating the entry from G1 to S phase, while the salvage antitumoral pathway which implicates it, especially in the absence of p53, is not fully characterized. We therefore attempted to identify the up‐ and down‐stream events involved in the activation of the E2F1‐dependent pro‐apoptotic pathway. For this purpose, a amonafide analogue, 7‐d (2‐(3‐(2‐(Dimethylamino)ethylamino)propyl)‐6‐(dodecylamino)‐1H‐benzo[de]isoquinoline‐1,3(2H)‐dione) was screened, which exhibited high antitumor activity against p53‐deficient human Chronic Myelogenous Leukemia (CML) K562 cells. Analysis of flow cytometry and western blots of K562 cells treated with 7‐d revealed an appreciable G2/M cycle arrest and apoptosis in a dose and time‐dependent manner via p53‐independent pathway. A striking increase in “Comet tail” formation and γ‐H2AX expression showed that DNA double strand breaks (DSB) were caused by 7‐d treatment. ATM/ATR signaling was reported to connect E2F1 induction with apoptosis in response to DNA damage. Indeed, 7‐d‐induced G2/M arrest and apoptosis were antagonized by ATM/ATR signaling inhibitor, Caffeine, which suggested that ATM/ATR signaling was activated by 7‐d treatment. Furthermore, the increased expression of E2F1, p73, and Apaf‐1 and p73 dissociation from HDM2 was induced by 7‐d treatment, however, knockout of E2F1 expression reversed p73, Apaf‐1, and p21Cip1/WAF1 expression, reactivated cell cycle progression, and inhibited 7‐d‐induced apoptosis. Altogether our results for the first time indicate that 7‐d mediates its growth inhibitory effects on CML p53‐deficient cells via the activation of an E2F1‐dependent mitochondrial and cell cycle checkpoint signaling pathway which subsequently targets p73, Apaf‐1, and p21Cip1/WAF1. J. Cell. Biochem. 113: 3165–3177, 2012. © 2012 Wiley Periodicals, Inc.
Studies on the interaction of CdTe QDs with bovine serum albumin
Authors: Liu Peng , Liu Yisi , Wang Qisui
Published: May 2012

BACKGROUND: Quantum dots (QDs) have attracted much attention in biological and medical applications. In particular, the interaction of QDs with bovine serum albumin (BSA) is crucial, and has been systematically investigated by various spectroscopic techniques under the physiological conditions.

RESULTS: The effects of ionic strength and pH on the interaction of CdTe QDs with BSA were studied by changing NaCl concentration and pH in mixed solution and making fluorescence spectroscopic measurements. The Stern‐Volmer quenching constant (Ka) of different ionic strength and pH were calculated, and information on the structural features of BSA were discussed by means of circular dichroism (CD) spectrum.

CONCLUSION: Both fluorescence (FL) and circular dichroism (CD) results indicated that hydrophobic and electrostatic interactions play a major role in the binding reaction, and the nature of quenching is static, resulting in forming QDs‐BSA complexes. Copyright © 2012 Society of Chemical Industry
Participation in unprofessional behaviors among hospitalists: A multicenter study
Authors: Reddy Shalini T. , Iwaz James A. , Didwania Aashish K. , O'Leary Kevin J. , Anderson R. Andy , Humphrey Holly J. , Farnan Jeanne M. , Wayne Diane B. , Arora Vineet M.
Published: May 2012

BACKGROUND:

Unprofessional behaviors undermine the hospital learning environment and quality of patient care.

OBJECTIVE:

To quantify perceptions of, and participation in, unprofessional behaviors among hospitalists.

DESIGN:

Observational survey study.

SETTING:

Three academic health centers.

SUBJECTS:

Hospitalists.

MEASUREMENTS:

Observation, participation in, and perceptions of unprofessional behaviors.

RESULTS:

Response rate was 76% (77/101). Nearly all behaviors were perceived as unprofessional (“unprofessional” or “somewhat unprofessional” on the Likert scale). Participation in egregious behaviors (ie, falsifying records) was low (<5%). The most frequent behaviors reported were having personal conversations in patient corridors (67.1%), ordering a test as “urgent” to expedite care (62.3%), and making fun of other physicians (40.3%). Four factors accounted for 76% of survey variance: (1) making fun of others; (2) learning environment (eg, texting during conferences); (3) workload management (eg, celebrating a blocked‐admission); and (4) time pressure (eg, signing out work early). Hospitalists with less clinical time (<50% full‐time equivalents [FTE]) were more likely to report making fun of others (β = 0.94 [95% CI 0.32–1.56], P = 0.004). Younger hospitalists (β = 0.87 [95% CI 0.07–1.67], P = 0.034) and those with administrative time (β = 0.61 [95% CI 0.11–1.10], P = 0.017) were more likely to report participating in workload management behaviors. Hospitalists who work night shifts were more likely to report participating in time‐pressure behaviors (β = 0.67 [95% CI 0.17–1.17], P = 0.010). Workload management and learning environment varied by site.

CONCLUSION:

While hospitalist participation in unprofessional behaviors is low, job characteristics (clinical, administrative, nights), age, and site were associated with different types of unprofessional behavior that may affect the learning environment and patient care. Journal of Hospital Medicine 2012;. © 2012 Society of Hospital Medicine
Changes in the linear relationship of ENSO–PDO under the global warming
Authors: Kwon MinHo , Yeh Sang‐Wook , Park Young‐Gyu , Lee Yoon‐Kyoung
Published: May 2012

We examine changes in El Niño and Southern Oscillation (ENSO)/Pacific Decadal Oscillation (PDO) relationship under the global warming using coupled climate models participated in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4). The temporal structure for the ENSO–PDO relationship is changed remarkably. The relationship between ENSO and PDO during the boreal winter (December, January and February) becomes stronger so that there would be more frequent in phase occurrence of ENSO and PDO (i.e. El Niño—a positive phase of PDO or La Niña—a negative phase of PDO). As PDO could constructively interfere with the ENSO‐related climate when ENSO and PDO are in phase, in the future one may expect stronger climate signal because of ENSO in the midlatitude. The IPCC AR4 model also shows that the Pacific North America‐like pattern is slightly shifted eastward and much stronger. We also discuss the possible reason for these changes. Copyright © 2012 Royal Meteorological Society
Holocene palaeoflood events recorded by slackwater deposits along the lower Jinghe River valley, middle Yellow River basin, China
Authors: Huang Chun Chang , Pang Jiangli , Zha Xiaochun , Zhou Yali , Su Hongxia , Zhang Yuzhu , Wang Hengsong , Gu Hongliang
Published: May 2012

Palaeoflood slackwater deposits (SWDs), are the natural record of overbank flooding and are often found within aeolian loess‐soil profiles along the river valleys of the middle Yellow River basin. These pedo‐stratigraphic sequences are studied using a multi‐disciplinarily approach to reconstruct Holocene hydro‐climatic variations. Our field investigations along the lower Jinghe River valley have identified palaeoflood SWDs at several sites along the riverbanks based on sedimentological criteria. Analytical results, including magnetic susceptibility, particle‐size distribution and concentrations of chemical elements, indicate that these well‐sorted palaeoflood SWD beds were deposited from the suspended sediment load in floodwaters. We identify two episodes of extraordinary palaeoflood events along the Jinghe River valley. These hydro‐climatic events were dated to 4200–4000 and 3200–2800 a BP, by using the optically stimulated luminescence method in combination with archaeological dating of retrieved anthropogenic remains, and with pedo‐stratigraphic correlations with the previously studied Holocene pedo‐stratigraphy in the Jinghe River drainage basin. The flooding events are therefore considered to be a regional expression of known climatic events in the northern hemisphere and demonstrate Holocene climate was far from stable. This study provides important data in understanding the interactions between regional hydro‐climatic systems and global change in semi‐arid and sub‐humid regions. Copyright © 2012 John Wiley & Sons, Ltd.
Stro‐1+ stromal cells have stem‐like features in giant cell tumor of bone
Authors: Lan Jie , Liu Xiaoguang , Rong Wei , Wei Feng , Jiang Liang , Yu Haiyan , Dang Gengting , Liu Zhongjun
Published: May 2012

Background

Giant cell tumor of bone (GCTB) is an aggressive benign bone tumor with poor prognosis whose neoplastic component is stromal cells (SCs). Tumor stem‐like cells (TSCs) have been demonstrated as precursors for tumor genesis and growth. The aim of this study is to identify TSCs in GCTB.

Methods

Stro‐1+ and Stro‐1− cells were isolated by fluorescence‐activated cell sorting (FACS). Stem‐like properties of both Stro‐1+ and Stro‐1− subpopulations were assessed using MTT colorimetric assays, cell cycle analyses, sphere formation assays, and differentiation assays. Molecular profiles were analyzed by flow cytometry, immunofluorescence, and qRT‐PCR.

Results

The existence of rare Stro‐1+ cells was confirmed in vitro using FACS and in vivo by immunohistochemistry. These Stro‐1+ cells exhibited higher proliferative and cisplatin‐resistant potentials than Stro‐1− cells. In serum‐free suspension cultures, Stro‐1+ SCs could form cell spheres and maintain self‐renewal. Furthermore, Stro‐1+ SCs could differentiate into two mesenchymal lineage cells: osteoblasts and adipocytes. Cell surface markers CD44, CD117, and CD133 and stem cell‐associated genes OCT3/4, NANOG, and ABCG2 were significantly higher in the Stro‐1+ subpopulation.

Conclusions

This study demonstrates that Stro‐1+ SCs in GCTB possess stem‐like biological and molecular phenotypes, indicating that they are the TSCs of GCTB. J. Surg. Oncol. 2012; 106:826–836. © 2012 Wiley Periodicals, Inc.
Short and long term degradation behaviour of Mg–1Ca magnesium alloys and protective coatings based on plasma‐chemical oxidation and biodegradable polymer coating in synthetic body fluid
Authors: Rosemann P. , Schmidt J. , Heyn A.
Published: May 2012

The main problem limiting the application of magnesium alloys as biodegradable implant material is its high degradation rate. In order to slow down the corrosion rate an extrusion process and specific coating systems based on plasma‐chemical oxidation (PCO) and organic dip coating with poly(L‐lactid‐co‐caprolacton) (PLLC) were applied on Mg–1Ca magnesium alloy. The additional PLLC coating is used to delay the start of substrate corrosion, while the purpose of the PCO coating is to decrease the substrate corrosion rate. The corrosion behaviour was investigated in synthetic body fluid (SBF) through measurement of the hydrogen evolution rate in long term tests and polarisation and electrochemical noise measurements in short term tests. The results showed significant differences between the cast and extruded alloys and a decrease of the corrosion rate due to corrosion product formation. The combination of both coating systems resulted in a significant delay of metal substrate corrosion and all coating systems showed good correlation between short and long term tests. The combination of the three investigation methods provides the possibility to gain more information about the degradation behaviour and break down of protective coatings.
A functional polymorphism C‐1310G in the promoter region ofKu70/XRCC6is associated with risk of renal cell carcinoma
Authors: Wang Wei , Pan Xuping , Huo Xinying , Yan Fu , Wang Meilin , Wang Dingxian , Gao Yanqin , Cao Qiang , Luo Dewei , Qin Chao , Yin Changjun , Zhang Zhengdong
Published: May 2012

The DNA repair geneKu70plays a key role in the DNA double strand break (DSB) repair system. Defects in DSB repair capacity can lead to genomic instability. We hypothesized that theKu70C‐1310G polymorphism (rs2267437) was associated with risk of renal cell carcinoma (RCC). We genotyped theKu70C‐1310G polymorphism in a case–control study of 620 patients and 623 controls in a Chinese population and assessed the effects of C‐1310G polymorphism on RCC susceptibility and survival. We then examined the functionality of this polymorphism. Compared with theKu70‐1310CC genotype, the CG and CG/GG genotypes had a significantly increased risk of RCC [adjusted odds ratio (OR) = 1.47, 95% confidence interval (CI) = 1.16–1.87 for CG and OR = 1.47, 95% CI = 1.16–1.86 for CG/GG]. However, the C‐1310G polymorphism did not influence the survival of RCC. The in vivo experiments with normal renal tissues revealed statistically significantly lowerKu70mRNA expression in samples with CG/GG genotypes relative to those with the CC genotype (P < 0.05). In vitro luciferase assays in various cell lines showed lower luciferase activity for the −1310G allele than for the −1310C allele. These results suggest that theKu70C‐1310G polymorphism is involved in the etiology of RCC and thus may be a marker for genetic susceptibility to RCC in Chinese populations. Larger studies are warranted to validate our findings. © 2012 Wiley Periodicals, Inc.
Simple wideband microstrip ring bandpass filter by utilizing forced harmonic suppression and direct feed line coupling
Authors: Liu Y. , Chang K.
Published: May 2012

A compact wideband microstrip ring bandpass filter is demonstrated in this article by means of forced harmonic suppression of a single square ring resonator with the absence of the feed line coupling gaps. Via‐hole and slit‐gap are incorporated as the forced boundary conditions of the resonator in the filter design. Both simulation and measurement results are provided and shown in good agreement. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1968–1970, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26935
Design considerations for compact microstrip resonant cells dedicated to efficient branch‐line miniaturization
Authors: Kurgan P. , Filipcewicz J. , Kitlinski M.
Published: May 2012

A conventional compact microstrip resonant cell (CMRC) has been thoroughly investigated to enhance its slow‐wave properties and subsequently ensure an efficient miniaturization of a microstrip circuit.The geometry of a classic CMRC has been improved in terms of slow‐wave effect in two progressive steps: (i) a single‐element topology has been replaced with a double‐element one and (ii) a high‐impedance section has been refined by means of an optimized meander line characterized by the minimal number of discontinuities. Vital usefulness of the novel CMRC in the process of microstrip circuit miniaturization has been proven and experimentally validated on the basis of a compact 3‐dB branch‐line coupler illustrating the possibilities of the approach. A prototype structure has been designed to mimic the performance of a classic coupler, simultaneously presenting a substantial 85% surface area reduction. The measured in‐band results are in excellent accordance with theoretical characteristics, whereas the broadband performance depicts an additional phenomenon, that is, the efficient suppression of unwanted signals up to the sixth harmonic. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1949–1954, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26980
A dynamic analysis of voluntary agreement implementation in Mexico
Authors: Franco‐García M. Laura , Sosa Alejandro , Bressers Hans Th. A.
Published: May 2012

This paper provides a descriptive historical analysis of failure and success factors during the implementation phase of environmental voluntary agreements (VAs) in Mexico. Secondary source data suggest that over the past two decades, perceptions of VAs have changed, and the purpose of this paper was to identify the driving factors behind that change. The analytical framework has three components: the first one refers to prior research findings on the perceptions of the Mexican private sector. The second and third components draw on previously reported ‘successful’ characteristics in voluntary approaches. By including a range of interest groups, the authors aimed to include those aspects of communication processes described as ‘lobbying’ by several authors. A major outcome of this analysis is that the low level of ‘trust’ among actors amounted to a failure factor when implementing a VA but that, after 14 years, the level of ‘trust’ had increased resulting in a cooperative attitude among actors. Communication effectiveness had an important role in the ‘trust’ building process, leading to the conclusion that communication processes had also improved. Although this cannot be claimed as a direct result of the lobbying processes, this research has identified the influence of ‘lobbying’ in facilitating the successful implementation of a VA. Copyright © 2012 John Wiley & Sons, Ltd.
Are Green Vehicles Worth the Extra Cost? The Case of Diesel‐Electric Hybrid Technology for Urban Delivery Vehicles
Authors: Krutilla Kerry , Graham John D.
Published: May 2012

A central question for environmental policy is whether the long‐term benefits of energy‐saving technologies are sufficient to justify their short‐term costs, and if so, whether financial incentives are needed to stimulate adoption. The fiscal effects of incentivizing new technologies, and the revenue effects of using the technology, are also policy relevant, given current fiscal constraints. This study evaluates the economic and fiscal effects of promoting diesel‐electric hybrid technology in urban delivery vehicles, an application supported by U.S. policymakers. An economic model is used to simulate the conditional probability density functions of the net present values (NPVs) of diesel electric hybrids annually from 2012 to 2030. The NPV time paths, which reflect fuel price, environmental, and technology trends, show the expected dates that hybrids become economically viable, and allow an evaluation of the net benefits of hybrid technology as an investment over the entire simulation horizon. The NPV distributions are computed for five stakeholder classes, including transportation firms, parties benefiting from reduced externality damages, state and local governments, and the larger society. The analysis shows that hybrid technology investment does not appear to be justified from a societal perspective at a 7 percent discount rate, but the probability for positive net returns increases substantially at a 3 percent rate.
Insulating polyimide films containing n‐type perylenediimide moieties
Authors: Damaceanu Mariana‐Dana , Rusu Radu‐Dan , Musteata Valentina‐Elena , Bruma Maria
Published: May 2012

Oxadiazole‐containing polyperyleneimides were prepared by high‐temperature solution polycondensation reaction of an aromatic diamino‐oxadiazole with a mixture of two dianhydrides, one containing a perylene moiety and the other containing a hexafluoroisopropylidene unit. Flexible films having good mechanical properties were made therefrom. The structure of the polymer films was confirmed using X‐ray photoelectron spectroscopy. Some polymer films were subjected to measurements of electrical insulating properties. The variation of the real and imaginary parts of the dielectric permittivity with frequency and temperature was recorded. The values of the dielectric constant, dielectric loss and specific resistance were obtained at 25 °C and in the frequency domain from 1 Hz to 130 kHz. The dielectric spectroscopy data showed distinct γ and β subglass transitions for these polymers at low activation energies. Electronic conduction through a hopping mechanism in these polyimide films was determined from AC conductivity measurements. Copyright © 2012 Society of Chemical Industry
Comprehensive identification of novel post‐translational modifications in cellular peroxiredoxin 6
Authors: Jeong Jaeho , Kim Yunghee , Kyung Seong Je , Lee Kong‐Joo
Published: May 2012

Peroxiredoxin 6 (PRDX6), a 1‐Cys peroxiredoxin, is a bifunctional enzyme acting both as a glutathione peroxidase and a phospholipase A2. However, the underlying mechanisms and their regulation mechanisms are not well understood. Because post‐translational modifications (PTMs) have been shown to play important roles in the function of many proteins, we undertook, in this study, to identify the PTMs in PRDX6 utilizing proteomic tools including nanoUPLC‐ESI‐q‐TOF MS/MS employing selectively excluded mass screening analysis (SEMSA) in conjunction with MODi and MODmap algorithm. We chose PRDX6 obtained from liver tissues from two inbred mouse strains, C57BL/6J and C3H/HeJ, which vary in their susceptibility to high‐fat diet‐induced obesity and atherosclerosis, and a B16F10 melanoma cell line for this study. When PRDX6 protein samples were separated on 2D‐PAGE based on pI, several PRDX6 spots appeared. They were purified and the low abundant PTMs in each PRDX6 spot were analyzed. Unexpected mass shifts (Δm = −34, +25, +64, +87, +103, +134, +150, +284 Da) observed at active site cysteine residue (Cys47) were quantified using precursor ion intensities. Mass differences of −34, +25, and +64 Da are presumed to reflect the conversion of cysteine to dehydroalanine, cyano, and Cys‐SO2‐SH, respectively. We also detected acrylamide adducts of sulfenic and sulfinic acids (+87 and +103 Da) as well as unknown modifications (+134, +150, +284 Da). Comprehensive analysis of these PTMs revealed that the PRDX6 exists as a heterogeneous mixture of molecules containing a multitude of PTMs. Several of these modifications occur at cysteine residue in the enzyme active site. Other modifications observed, in PRDX6 from mouse liver tissues included, among others, mono‐ and dioxidation at Trp and Met, acetylation at Lys, and deamidation at Asn and Gln. Comprehensive identification of the diverse PTMs occurring in this bifunctional PRDX6 enzyme should help understand how PRDX6 plays key roles in oxidative stresses.
The enthalpy of formation of methionine revisited
Authors: Roux María Victoria , Notario Rafael , Segura Marta , Chickos James S. , Liebman Joel F.
Published: May 2012

Methionine (2‐amino‐4‐(methylthio)butanoic acid) is a sulfur‐containing essential α‐amino acid. Despite its importance, its enthalpy of formation is contentious. From the analysis of its polymorphism confirms that the previously reported calorimetric experiments were made in the temperature interval in which a phase transitions occurs. A new value for the enthalpy of formation is suggested based on these results, as well as G4 quantum chemical calculations and thermochemical estimates. From the analysis of experimental enthalpy of formation measurements, the group increment temperature adjusted enthalpy of sublimation, quantum chemical calculations, and difference quantity derived estimates, our recommended value for the gas phase enthalpy of formation of methionine is –(430 ± 10) kJ·mol−1. Copyright © 2012 John Wiley & Sons, Ltd.
Improved efficiency of hybrid solar cell based on thiols‐passivated CdS quantum dots and poly(3‐hexythiophene)
Authors: Liu Xinmei , Jiang Yang , Lan Xinzheng , Zhang Yugang , Liu Chao , Li Junwei , Wang Binbin , Yu Yongqiang , Wang Wenjun
Published: May 2012

A bulk‐heterojunction hybrid solar cell based on CdS quantum dots (QDs) as electron acceptor and P3HT as donor was fabricated for the first time. The CdS QDs synthesized by a one‐pot method had good crystallinity and stability. The hybrid thin film of CdS‐QDs and conjugated polymer was made by simple spin‐coating deposition of CdS‐QDs/P3HT composite solution on ITO substrates and then treated by bidentate ligand ethanedithiol. Under AM1.5G illumination, the power‐conversion efficiency (PCE) of the thiol‐treated monolayer film was more than three times higher than that of the untreated device. The hybrid solar cell based on the assembled trilayer blend film with ethanedithiol by a layer‐by‐layer approach exhibited a further improved PCE of 0.86%, which was sixfold higher than that of the thiol‐treated monolayer device. The results can be explained via ethanedithiol effectively displacing the existing stearate ligands on the surface of QDs in situ and connecting nanoparticles by its end function group, shortening the interdot space and thus improving electron transport between the QDs. The morphology of the thiol‐treated blend film was briefly investigated.
Fabrication of Cu2ZnSnS4 absorbers by sulfurization of Sn‐rich precursors
Authors: Ge Jie , Yu Wenlei , Cao Hong , Jiang Jinchun , Ma Jianhua , Yang Lihong , Yang Pingxiong , Hu Zhigao , Chu Junhao
Published: May 2012

Cu2ZnSnS4 (CZTS) absorbers were grown by sulfurization of the Sn‐rich precursors that were cosputtered from a CuSn target (2 in.) and a ZnS target (2 in.). The excess Sn in the precursor could limit the decomposition of CZTS during the long sulfurization process at 510 °C. The sulfurized CZTS film cosputtered with CuSn 45 W and ZnS 70 W exhibits the intended bandgap of 1.53 eV, main Raman mode at 335.5 cm−1 and a slightly Sn‐rich composition. As the sputtering power of the CuSn target was increased from 45 to 60 W, the corresponding films consisted of a CZTS phase and several Sn‐rich phases (SnS/Sn2S3/Cu4Sn7S16). Conversely, when this sputtering power was reduced to 35 W, the resultant film consisted of a CZTS phase and a ZnS secondary phase. Besides, Raman scattering shows that the increased sputtering power of the CuSn target is related with the redshift and the increased FWHMs of primary Raman modes for the resultant films. X‐ray diffraction data show the (112)‐oriented growth and lattice expansion for the obtained CZTS films.
Effects of boron–nitrogen pair on the electronic properties of zigzag graphene nanoribbon
Authors: Wang Zhiyong , Zhao Shihua , Xiao Jianrong
Published: May 2012

The geometry structures and electronic properties of zigzag graphene nanoribbons (ZGNRs) with boron–nitrogen (BN) pair edge‐doping are investigated by performing first‐principles calculations based on density functional theory. The calculated results show that the BN pair substitutional doping at the edge changes the conducting characteristic of ZGNR to a half‐metallic one with increasing concentration of boron (nitrogen) dopants, which may be attributed to the changes of the ionic potential difference between boron and nitrogen atoms located at the edge of the ZGNRs. It is found that the concentration of dopants at the edge regulate the electronic properties of ZGNRs. It is predicted that the theoretical results may be valuable in the design of GNR‐based spintronics devices.
Factors influencing Northern Hemisphere winter mean atmospheric circulation anomalies during the period 1960/61 to 2001/02
Authors: Greatbatch R. J. , Gollan G. , Jung T. , Kunz T.
Published: May 2012

Influences from the Tropics, the stratosphere and the specification of observed sea surface temperature and sea‐ice (SSTSI) on Northern Hemisphere winter mean circulation anomalies during the period 1960/61 to 2001/02 are studied using a relaxation technique applied to the ECMWF model. On interannual time‐scales, the Tropics strongly influence the Pacific sector but also the North Atlantic sector, although weakly. The stratosphere is found to be influential on the North Atlantic Oscillation (NAO) on interannual time‐scales but is less important over the Pacific sector. Adding the observed SSTSI to the tropical relaxation runs generally improves the model performance on interannual time‐scales but degrades/enhances the model's ability to capture the 42‐year trend over the Pacific/Atlantic sector. While relaxing the stratosphere to the reanalysis fails to capture the trend over the whole 42‐year period, the stratosphere is shown to be influential on the upward trend of the NAO index from 1965 to 1995, but with reduced amplitude compared to previous studies. Influence from the Tropics is found to be important for the trend over both time periods and over both sectors although, across all experiments, we can account for only 30% of the amplitude of the hemispheric trend. Copyright © 2012 Royal Meteorological Society
Measuring PPM Non‐conformities for Processes with Asymmetric Tolerances
Authors: Pearn W. L. , Wu C. H.
Published: May 2012

Process yield has been the most basic and common criterion used in the manufacturing industry for evaluating process capability. The Cpk index has been used widely in the manufacturing industry. In this note, we considered a generalization of Cpk index which handles processes involving a target T with asymmetric tolerances. Particularly, we established a formula for measuring the PPM non‐conformities for given ratios of the two‐side tolerances. We proved the validity of the established formula and tabulated the upper bounds on PPM non‐conformities for various given Cpk index values and ratios of the two‐side tolerances. Copyright © 2012 John Wiley & Sons, Ltd.
Evaluation of Generalised Proportional Intensities Models with Application to the Maintenance of Gas Turbines
Authors: Alkali B.
Published: May 2012

In this paper generalised proportional intensities models are fitted to gas turbine generator failure and maintenance data. The systems of interest have identical maintenance procedures and information about preventive maintenance (PM) and corrective maintenance (CM) activities is known. Closed‐form maximum log‐likelihood estimates of the model parameters are evaluated, and the model goodness‐of‐fit is measured. A simulation study is conducted to determine an optimal cost effective PM schedule. Our analysis and results facilitate decision support for determining the cost‐optimal maintenance strategy. Copyright © 2012 John Wiley & Sons, Ltd.
Mevalonate Metabolism Regulates Basal Breast Cancer Stem Cells and Is a Potential Therapeutic Target
Authors: Ginestier Christophe , Monville Florence , Wicinski Julien , Cabaud Olivier , Cervera Nathalie , Josselin Emmanuelle , Finetti Pascal , Guille Arnaud , Larderet Gaelle , Viens Patrice , Sebti Said , Bertucci François , Birnbaum Daniel , Charafe-Jauffret Emmanuelle
Published: May 2012

There is increasing evidence that breast tumors are organized in a hierarchy, with a subpopulation of tumorigenic cancer cells, the cancer stem cells (CSCs), which sustain tumor growth. The characterization of protein networks that govern CSC behavior is paramount to design new therapeutic strategies targeting this subpopulation of cells. We have sought to identify specific molecular pathways of CSCs isolated from 13 different breast cancer cell lines of luminal or basal/mesenchymal subtypes. We compared the gene expression profiling of cancer cells grown in adherent conditions to those of matched tumorsphere cultures. No specific pathway was identified to be commonly regulated in luminal tumorspheres, resulting from a minor CSC enrichment in tumorsphere passages from luminal cell lines. However, in basal/mesenchymal tumorspheres, the enzymes of the mevalonate metabolic pathway were overexpressed compared to those in cognate adherent cells. Inhibition of this pathway with hydroxy-3-methylglutaryl CoA reductase blockers resulted in a reduction of breast CSC independent of inhibition of cholesterol biosynthesis and of protein farnesylation. Further modulation of this metabolic pathway demonstrated that protein geranylgeranylation (GG) is critical to breast CSC maintenance. A small molecule inhibitor of the geranylgeranyl transferase I (GGTI) enzyme reduced the breast CSC subpopulation both in vitro and in primary breast cancer xenografts. We found that the GGTI effect on the CSC subpopulation is mediated by inactivation of Ras homolog family member A (RHOA) and increased accumulation of P27kip1 in the nucleus. The identification of protein GG as a major contributor to CSC maintenance opens promising perspectives for CSC targeted therapy in basal breast cancer.
Interpreting “systems architecting”
Authors: Emes M. R. , Bryant P. A. , Wilkinson M. K. , King P. , James A. M. , Arnold S.
Published: May 2012

The UK Chapter of the International Council on Systems Engineering (INCOSE UK) commissioned research to illustrate the variety of usage of the terms architecture and architecting in the systems engineering community. These terms, though widely used, are rarely strictly defined, and the meaning attributed to the terms is not consistent even in formal publications. Using soft systems methodology, this research has analyzed three published sources (MODAF [http://www.modaf.org.uk, 2008], The Art of Systems Architecting by Maier and Rechtin [CRC Press, 2009], and ISO/IEC 42010 [2011]), and conducted a series of interviews with systems architecting practitioners. This research was set in context by a historical review of the use of the term systems architecting. Twelve contentious questions in systems architecting are discussed, and six perspectives on systems architecting presented, including three basic worldviews of the relationship between systems engineering and systems architecting. One model sees systems architecting as simply a rebranding of systems engineering to broaden its appeal with no change in content. Another model sees systems engineering restricted to its traditional processes, with systems architecting adding to systems engineering through external processes. The final model, and the most popular among the systems engineering community surveyed, sees systems architecting addressing shortcomings in traditional sequential lifecycle models by stretching the content of systems engineering to include new elements under the banner of systems architecting. © 2012 Wiley Periodicals, Inc. Syst Eng 15.
Do pocket‐sized ultrasound machines have the potential to be used as a tool to triage patients in obstetrics and gynecology?
Authors: Sayasneh A. , Preisler J. , Smith A. , Saso S. , Naji O. , Abdallah Y. , Stalder C. , Daemen A. , Timmerman D. , Bourne T.
Published: May 2012

Objectives

To evaluate the performance and potential impact on patient management of a pocket‐sized ultrasound machine (PUM) in comparison to high‐specification ultrasound machines (HSUM).

Methods

This was an observational cohort study with 204 unselected patients in three categories: 1) women with pain and bleeding in early pregnancy (101 patients); 2) women presenting for routine obstetric ultrasound assessment (53 patients); 3) women with possible gynecological pathology (50 patients). Scans were carried out transabdominally using a PUM. A second operator repeated the examination transvaginally and/or transabdominally, depending on the clinical indication, using an HSUM. The operators were blind to each other's findings.

Results

In the early pregnancy group, there was good to very good agreement between the PUM and HSUM for identifying the presence or absence of an embryo, gestational sac, fetal heart motion, pregnancy location and final diagnostic outcome (kappa coefficients, 0.844, 0.843, 0.729, 0.785 and 0.812, respectively; P < 0.0001). In the obstetric ultrasound group there was good to very good agreement for fetal presentation, placental location and placental position (kappa coefficients, 0.924, 0.924 and 0.647, respectively; P < 0.0001). In the gynecological pathology group, there was very good agreement for final diagnosis and type of ovarian mass (low risk or complex) (kappa coefficients, 0.846 and 0.930, respectively; P < 0.0001). For the measured continuous variables, there was close agreement for crown–rump length, mean sac diameter, femur length and mean diameter of an ovarian mass, but not for endometrial thickness. Neither patient demographics (age, body mass index, ethnicity) nor operator experience and familiarity with a PUM had an impact on agreement between the two machines. If a PUM had been the only equipment available for an initial assessment, only two cases would have led to a suboptimal patient management plan.

Conclusion

The findings and final diagnosis in the three study groups were similar for both a PUM used transabdominally and an HSUM used transvaginally and/or transabdominally. Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.
Prenatal diagnosis and outcome of absent pulmonary valve syndrome: contemporary single‐center experience and review of the literature
Authors: Wertaschnigg D. , Jaeggi M. , Chitayat D. , Shannon P. , Ryan G. , Thompson M. , Yoo S. J. , Jaeggi E.
Published: May 2012

Objective

To review the anomaly spectrum of prenatally detected absent pulmonary valve syndrome (APVS) and the outcome after diagnosis. Previous fetal studies reported survival rates of ≤ 25% for patients with intended postnatal care.

Methods

Clinical data and echocardiograms of 12 cases with a fetal diagnosis of APVS between 2000 and 2010 were analyzed in this retrospective single‐center study. Collected parameters included: gestational age at referral, associated fetal abnormalities, cardiothoracic ratio, maximum diameters of pulmonary annulus and main and branch pulmonary arteries, ventricular dimensions and function as well as ventricular Doppler flows. Karyotyping included fluorescence in‐situ hybridization (FISH) analysis for microdeletion 22q11.2.

Results

Median gestational age at diagnosis was 24 weeks. Three subtypes of APVS were observed: (1) with tetralogy of Fallot (TOF) and no arterial duct (n = 10; 83%); (2) isolated, with a large arterial duct (n = 1; 8%); and (3) with tricuspid atresia, right ventricular dysplasia and a restricted duct (n = 1; 8%). The cardiothoracic ratio and pulmonary artery dimensions were increased in all cases. The karyotype was abnormal in 70% of fetuses with TOF and their mortality rate was significantly higher due to pregnancy termination (n = 3) or perinatal demise (n = 2) (hazard ratio, 5; 95% CI, 0.87−28.9; P = 0.015). Of seven live births with active postnatal care, six children (86%) were alive without residual respiratory symptoms at a median follow‐up of 4.7 (range, 2.1−10.6) years.

Conclusion

Outcome after fetal diagnosis of APVS was significantly better in this study compared with those of previous fetal series, with a low mortality rate for actively managed patients.
Pulmonary outflow tract obstruction in fetuses with complex congenital heart disease: predicting the need for neonatal intervention
Authors: Quartermain M. D. , Glatz A. C. , Goldberg D. J. , Cohen M. S. , Elias M. D. , Tian Z. , Rychik J.
Published: May 2012

Objective

To identify prenatal echocardiographic markers that could predict the need for neonatal intervention in fetuses with right ventricular outflow tract obstruction.

Methods

This was a retrospective study of 52 fetuses with right ventricular outflow tract obstruction. Echocardiograms were evaluated for fetuses with either two‐ventricle anatomy with a large ventricular septal defect or single‐ventricle anatomy. Fetuses with pulmonary atresia were excluded. Parameters were compared between groups that did and did not require an intervention at age < 30 days.

Results

Fifty‐two fetuses were studied; 20 (38%) underwent neonatal intervention and 32 (62%) did not. The most common diagnosis was tetralogy of Fallot (n = 32). Fetuses with two ventricles that required an intervention had lower pulmonary valve diameter Z‐score (PV‐Z‐score) (−4.8 ± 2.1 vs −2.6 ± 1.1; P = 0.0002) and lower pulmonary valve to aortic valve annular diameter ratio (PV/AoV) (0.53 ± 0.15 vs 0.66 ± 0.1; P = 0.003). Using a PV/AoV ratio of < 0.6 or a PV‐Z‐score of < −3 at final echocardiographic examination was highly sensitive (92%) but poorly specific (50%), whereas classifying direction of flow in the ductus arteriosus as either normal (all pulmonary‐to‐aorta) or abnormal (aorta‐to‐pulmonary or bidirectional) was both highly sensitive (100%) and specific (95%) for predicting the need for a neonatal intervention. Parameters for the single‐ventricle cohort did not reach statistical significance.

Conclusions

Analysis of the pulmonary outflow tract and ductus arteriosus flow in the fetus with complex congenital heart disease can aid in identifying those that will require a neonatal intervention to augment pulmonary blood flow. This has important implications for the planning of delivery strategies.
Synthesis and Characterization of the New Mixed Valent Compound Mn5VO8
Authors: Clemens Oliver , Haberkorn Robert , Kohlmann Holger , Springborg Michael , Beck Horst Philipp
Published: May 2012

This work describes the synthesis and characterization of the new compound Mn5VO8. This phase is the only known ternary mixed valent compound in the system MnO‐Mn2O3‐V2O5 and crystallizes in a so far unknown crystal structure, which leads to coordination for the Jahn‐Teller cation Mn3+ in distorted octahedra (elongated and compressed, respectively). The material can be prepared by solid state reaction at 900 °C in a monoclinic [a = 19.5605(10) Å, b = 6.2184(3) Å, c = 5.4276(3) Å, β = 100.078(4)°, C2/m, Z = 4] as well as in a triclinic [a = 5.4320(2) Å, b = 6.2066(2) Å, c = 10.2443(4) Å, α = 107.035(3)°, β = 99.469(3)°, γ = 90.422(4)°, P$\bar{1}$, Z = 2] modification, depending on the composition of the starting material mixture (7MnO + V2O5 versus 0.5Mn2O3 + 4MnO + 0.5V2O5). Quantum mechanical calculations were carried out in order to get more detailed information on the material. Thereby, ionic charges could be assigned to the manganese atoms at the different crystallographic sites.
Stabilization of an Intramolecularly Coordinated Stannylidenium Cation
Authors: Martincová Jana , Dostál Libor , Růžička Aleš , Herres‐Pawlis Sonja , Jambor Roman
Published: May 2012

The treatment of trans‐{[2, 6‐(Me2NCH2)2C6H3]SnI}2PtI2 with Na(pyt) (pyt = 2‐mercaptopyridine) yielded the unprecedented complex {{[2, 6‐(Me2NCH2)2C6H3]Sn}Pt(μ‐pyt)2I} (1), where a Sn←N coordinated stannylidenium (LSnII)+ fragment donates a to a [PtII(pyt)2I]– anion. Compound 1 was characterized by NMR spectroscopy and molecular structure was determined by X‐ray diffraction analysis. The bonding situation in 1 was analyzed by DFT studies.
Synthesis and Electrochemical Behavior of Mixed Organoboron/Organomercury Compounds
Authors: Melaimi Mohand , Gabbaï François P.
Published: May 2012

As part of our ongoing interest in the synthesis and reduction chemistry of organoboron species, we have investigated the synthesis of mixed organoboron/organomercury complexes by reaction of the Li(THF)4 salt of dimesityl‐1, 8‐naphthalenediylborate with 1, 2‐(HgCl)2C6F4 and 1, 3‐(HgCl)2C6F4, respectively. The resulting tetranuclear B2Hg2 complexes (2 and 3, respectively) were characterized by multinuclear NMR spectroscopy and single‐crystal X‐ray analysis. The cyclic voltammogram of complex 2, which features a B–Hg–Hg‐B core connected by an ortho‐phenylene (Hg–Hg connection) and two peri‐naphthalenediyl linkers (B–Hg connection), shows significant coupling of the two electroactive boryl units, presumably via a direct σ interaction of the vacant p orbitals of the four neighboring Lewis acids. This conclusion is supported by DFT calculations, which show that the LUMO of 2 spans the four Lewis acids, with a major in phase contribution from the boron 2p orbitals and the mercury 6p orbitals.