bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal Excitation of H2 and D2 at Clean Metal Surfaces. Noteworthy Differences between d‐ and s‐Metals
Authors: Gentsch H. , Adamitzki W. , Ave H. , Bothe F.‐W. , Fischer H. , Rogge B. 
Published: July 2012

AbstractAd‐ and desorption measurements of hydrogen (deuterium) on clean metal surfaces under high and ultrahigh vacuum conditions by means of the capillary flow method with pressure control only by inert gauges show a small fraction of desorbing molecules in an activated state. These molecules adsorb on glass and on carbon, respectively, or are able to reduce copper‐I‐oxid. This experiment indicates two different ways for activation of hydrogen molecules in collision with hot metal surfaces: (i) the well known dissociation of molecules dominant at TS > 1100 K and (ii) new, the excitation at hydrogen (deuterium) molecules at 800 < Ts < 1100 K with activation energies of E = 0.52 (0.37) eV. The results show a significant pressure dependence of the vibration accommodation coefficient. The s‐metals Cu and Au are total ineffective in dissociation and in activation molecules, respectively. The energy for excitation (H2, D2) is in accordance with the term difference of the harmonic oscillator.
The Dipole Fluctuations of Ellipsoidal Samples
Authors: Schröer Wolfram 
Published: July 2012

AbstractStarting from the calculation of the dielectric polarization of a macroscopic ellipsoid containing a fluid of polarizable dipoles surrounded by a uniform dielectric by means of electrostatics the macroscopic expressions of the dipole fluctuations are derived as a generalization of the Fröhlich relations concerning a sphere. The result holds for polar, non‐polar, and non‐polarizable molecules and includes samples of spherical, disc and needle geometry surrounded by vacuum, a metal or a medium of the same dielectric constant. The explicit evaluation of the reaction field leads independently of the surrounding medium to the same expressions which hold for samples in vacuum. The evaluation of the dipolar long‐range terms inside the sample leads to expressions of the form of the Clausius‐Mossotti relation which are independent of the boundary conditions and depend on the molecular properties and short‐range correlations only. Considering a sample containing only one molecule the theory leads to a generalization of the Onsager model for ellipsoidal molecules which agrees for small deviations of the spherical shape with the Böttcher‐Scholte model.
Diffusion Coefficients and Thermal Diffusion Factors for Five Binary Systems of Methane with the Noble Gases
Authors: Trengove R. D. , Robjohns H. L. , Dunlop Peter J. 
Published: July 2012

AbstractUsing two‐bulb cells and accurate thermistor bridges, diffusion coefficients and thermal diffusion factors have been measured for binary mixtures of methane with helium, neon, argon, krypton and xenon. The data and existing cross‐term virial coefficients have been employed to generate (m, 6, 8) potential functions. Several potential functions which have been reported in the literature have been tested.
Chiral Recognition of N‐Phthaloyl, N‐Tetrachlorophthaloyl, and N‐Naphthaloyl α‐Amino Acids and Their Esters on Polysaccharide‐Derived Chiral Stationary Phases
Authors: Kim Byoung‐Hyoun , Lee Sang Uck , Moon Dong Cheul 
Published: July 2012

ABSTRACTEnantiomeric separations of N‐phthaloyl (N‐PHT), N‐tetrachlorophthaloyl (N‐TCPHT), and N‐naphthaloyl (N‐NPHT) α‐amino acids and their esters were examined on several kinds of polysaccharide‐derived chiral stationary phases (CSPs). Resolution capability of CSPs was greater Chiralcel OF than the others for N‐PHT and N‐NPHT α‐amino acids and their esters. In N‐TCPHT α‐amino acids and their esters, good enantioselectivities showed Chiralcel OG for N‐TCPHT α‐amino acids, Chiralpak AD for N‐TCPHT α‐amino acid methyl esters, and Chiralcel OD for N‐TCPHT α‐amino acid ethyl esters, respectively. From the results of liquid chromatography and computational chemistry, it is concluded that l‐form is preferred and more retained with electrostatic interaction in case of interaction between N‐PHT α‐amino acid derivatives and Chiralcel OF, N‐TCPHT α‐amino acid derivatives and Chiralcel OD, and N‐NPHT α‐amino acid derivatives and Chiracel OF. On the other hand, d‐form is preferred and more retained with van der Waals interaction in case of interaction between N‐TCPHT α‐amino acid ester derivatives and Chiralcel OG and Chiralpak AD. Chirality 24:1037–1046, 2012. © 2012 Wiley Periodicals, Inc.
The defect in humoral immunity in patients with Nijmegen breakage syndrome is explained by defects in peripheral B lymphocyte maturation
Authors: Piątosa Barbara , van der Burg Mirjam , Siewiera Katarzyna , Pac Małgorzata , van Dongen Jacques J. M. , Langerak Anton W. , Chrzanowska Krystyna H. , Bernatowska Ewa 
Published: July 2012

AbstractPatients with an immunodeficiency in the course of Nijmegen breakage syndrome (NBS) that is caused by mutations in the NBN/NBS1 gene are prone to recurrent infections and malignancies, due to a defective DNA double‐strand breaks repair mechanism. Four‐color flow cytometry was used to analyze changes in B lymphocyte subsets reflecting the most important stages of peripheral B cell maturation. It was demonstrated that the humoral immune defect observed in NBS patients was caused by reduced numbers of B lymphocytes, but also by their aberrant maturation. Reduced relative and absolute counts of naïve and memory B cells were accompanied by a significant accumulation of the natural effector B lymphocytes. The elevated proportion of IgM‐only memory and reduced proportion of IgM‐negative cells within the memory B cell pool suggests that there is class‐switch recombination defect in this population of cells in NBS patients, resulting in inadequate production of immunoglobulins. Because of the reduced T‐cell counts, the T‐cell dependent antigen response is severely impaired resulting in a lower frequency of memory B‐cells. The T‐cell independent B‐cell differentiation pathway seems less affected. The reduced IgG and IgA levels in patients with NBS are caused both by ineffective class switch, at least due to poor T cell help, and low number of memory B cells. This study illustrates that the NBN gene product nibrin plays an important role at different levels in the B‐cell system. © 2012 International Society for Advancement of Cytometry
Interaction of inhibition and triplets of excitatory spikes modulates the NMDA‐R‐mediated synaptic plasticity in a computational model of spike timing‐dependent plasticity
Authors: Cutsuridis Vassilis 
Published: July 2012

AbstractSpike timing‐dependent plasticity (STDP) experiments have shown that a synapse is strengthened when a presynaptic spike precedes a postsynaptic one and depressed vice versa. The canonical form of STDP has been shown to have an asymmetric shape with the peak long‐term potentiation at +6 ms and the peak long‐term depression at −5 ms. Experiments in hippocampal cultures with more complex stimuli such as triplets (one presynaptic spike combined with two postsynaptic spikes or one postsynaptic spike with two presynaptic spikes) have shown that pre–post–pre spike triplets result in no change in synaptic strength, whereas post–pre–post spike triplets lead to significant potentiation. The sign and magnitude of STDP have also been experimentally hypothesized to be modulated by inhibition. Recently, a computational study showed that the asymmetrical form of STDP in the CA1 pyramidal cell dendrite when two spikes interact switches to a symmetrical one in the presence of inhibition under certain conditions. In the present study, I investigate computationally how inhibition modulates STDP in the CA1 pyramidal neuron dendrite when it is driven by triplets. The model uses calcium as the postsynaptic signaling agent for STDP and is shown to be consistent with the experimental triplet observations in the absence of inhibition: simulated pre–post–pre spike triplets result in no change in synaptic strength, whereas simulated post–pre–post spike triplets lead to significant potentiation. When inhibition is bounded by the onset and offset of the triplet stimulation, then the strength of the synapse is decreased as the strength of inhibition increases. When inhibition arrives either few milliseconds before or at the onset of the last spike in the pre–post–pre triplet stimulation, then the synapse is potentiated. Variability in the frequency of inhibition (50 vs. 100 Hz) produces no change in synaptic strength. Finally, a 5% variation in model's calcium parameters (calcium thresholds) proves that the model's performance is robust. © 2012 Wiley Periodicals, Inc.
Efficacy of platelet‐rich plasma gel and hyaluronan hydrogel as carriers of electrically polarized hydroxyapatite microgranules for accelerating bone formation
Authors: Ohba Seiko , Wang Wei , Itoh Soichiro , Takagi Yuzo , Nagai Akiko , Yamashita Kimihiro 
Published: July 2012

AbstractThe technology for electrical polarization and characterization of hydroxyapatite (HA) microgranules has been developed. This study aimed to examine and compare the efficacy of composites comprising electrically polarized HA (pHA) microgranules and platelet‐rich plasma (PRP) or hyaluronan (HAN) in osteoconductivity. Composites of HA microgranules with or without electrical polarization and either PRP or HAN (PRP+pHA, PRP+HA, HAN+pHA, and HAN+HA, respectively), as well as pHA and HA microgranules were implanted randomly into holes created in the medial femoral condyle or tibial tuberosity of rabbits. As a control, PRP or HAN gel alone was implanted, or the bone holes were left empty. Each group included six animals. After 6 weeks, histological examination was performed, and osteoclastic and osteoblastic cell activities were assessed by cell counting. Although PRP alone could not induce bone formation, PRP+pHA and PRP+HA composites, especially the former, activated osteogenic cells and enhanced bone formation. This effect was not prominent in the HAN+pHA and HAN+HA composites. PRP+HA composites formed a gel in which the ceramic particles were dispersed and entrapped in the fibrin network of PRP. It is assumed that these particles provide scaffolds for osteogenic cells, and when electrically polarized, can activate the cells in co‐operation with the positive effects of the PRP, resulting in enhanced bone formation. Conversely, it is conceivable that this composite gel cannot act as an accelerator for woven bone formation, because HAN with low viscoelasticity is absorbed rapidly after implantation, the hydrated network containing HA microgranules is destroyed, and the HA microgranules effuse with HAN from the bone hole. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 100A:3167–3176, 2012.
INNOVATIVE FEATURES IN POVERTY REDUCTION PROGRAMMES: AN IMPACT EVALUATION OF CHILE SOLIDARIO ON HOUSEHOLDS AND CHILDREN
Authors: Martorano Bruno , Sanfilippo Marco 
Published: July 2012

AbstractThe Chile Solidario programme is an innovative conditional cash transfer (CCT) in the Latin American context, aimed at addressing specifically the multidimensional nature of poverty. This paper, using data from the Panel Caracterización Socioeconómica Nacional (CASEN) Survey for the years 2001 and 2006, presents an impact evaluation of this programme. Using matching techniques to compare participants in the programme with a control group, and a difference‐in‐differences estimator, we evaluate its impact on various socioeconomic dimensions and results at the household and child level are differentiated. At the household‐level, we find that the programme has a significant impact on lifting families out of extreme poverty and that it does not have disincentive effects on labour participation. For children, we find that it has contributed to increasing participation in school for those between the ages of 6 and 15 years, and to increased enrolment with the public health services. Copyright © 2012 John Wiley & Sons, Ltd.
Pd‐Catalysed Direct Arylation Polymerisation for Synthesis of Low‐Bandgap Conjugated Polymers and Photovoltaic Performance
Authors: Chang Shu‐Wei , Waters Huw , Kettle Jeff , Kuo Zi‐Rui , Li Chun‐Han , Yu Chin‐Yang , Horie Masaki 
Published: July 2012

AbstractLow‐bandgap conjugated copolymers based on a donor–acceptor structure have been synthesised via palladium‐complex catalysed direct arylation polymerisation. Initially, we report the optimisation of the synthesis of poly(cyclopentadithiophene‐alt‐benzothiadiazole) (PCPDTBT) formed between cyclopentadithiophene and dibromobenzothiadiazole units. The polymerisation condition has been optimised, which affords high‐molecular‐weight polymers of up to Mn = 70 k using N‐methylpyrrolidone as a solvent. The polymers are used to fabricate organic photovoltaic devices and the best performing PCPDTBT device exhibits a moderate improvement over devices fabricated using the related polymer via Suzuki coupling. Similar polymerisation conditions have also been applied for other monomer units.
Evaluation of heterogeneous metabolic profile in an orthotopic human glioblastoma xenograft model using compressed sensing hyperpolarized 3D 13C magnetic resonance spectroscopic imaging
Authors: Park Ilwoo , Hu Simon , Bok Robert , Ozawa Tomoko , Ito Motokazu , Mukherjee Joydeep , Phillips Joanna J. , James C. David , Pieper Russell O. , Ronen Sabrina M. , Vigneron Daniel B. , Nelson Sarah J. 
Published: July 2012

AbstractHigh resolution compressed sensing hyperpolarized 13C magnetic resonance spectroscopic imaging was applied in orthotopic human glioblastoma xenografts for quantitative assessment of spatial variations in 13C metabolic profiles and comparison with histopathology. A new compressed sensing sampling design with a factor of 3.72 acceleration was implemented to enable a factor of 4 increase in spatial resolution. Compressed sensing 3D 13C magnetic resonance spectroscopic imaging data were acquired from a phantom and 10 tumor‐bearing rats following injection of hyperpolarized [1‐13C]‐pyruvate using a 3T scanner. The 13C metabolic profiles were compared with hematoxylin and eosin staining and carbonic anhydrase 9 staining. The high‐resolution compressed sensing 13C magnetic resonance spectroscopic imaging data enabled the differentiation of distinct 13C metabolite patterns within abnormal tissues with high specificity in similar scan times compared to the fully sampled method. The results from pathology confirmed the different characteristics of 13C metabolic profiles between viable, non‐necrotic, nonhypoxic tumor, and necrotic, hypoxic tissue. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
Skeletal age assessment in children using an open compact MRI system
Authors: Terada Yasuhiko , Kono Saki , Tamada Daiki , Uchiumi Tomomi , Kose Katsumi , Miyagi Ryo , Yamabe Eiko , Yoshioka Hiroshi 
Published: July 2012

AbstractMRI may be a noninvasive and alternative tool for skeletal age assessment in children, although few studies have reported on this topic. In this article, skeletal age was assessed over a wide range of ages using an open, compact MRI optimized for the imaging of a child's hand and wrist, and its validity was evaluated. MR images and their three‐dimensional segmentation visualized detailed skeletal features of each bone in the hand and wrist. Skeletal age was then independently scored from the MR images by two raters, according to the Tanner–Whitehouse Japan system. The skeletal age assessed by MR rating demonstrated a strong positive correlation with chronological age. The intrarater and inter‐rater reproducibilities were significantly high. These results demonstrate the validity and reliability of skeletal age assessment using MRI. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
Analysis of the motivations, generativity and demographics of the food bank volunteer
Authors: Agostinho Denise , Paço Arminda 
Published: July 2012

The increasing attention received by the topic ‘volunteering’ is not surprising because it is an activity involving a great number of individuals across all age categories; it includes a considerable number of activities and is fundamental to the effective functioning of many organizations. Thus, the social value of volunteers is unquestionable to civil society. Understanding volunteer's motivations has been regularly recognized by researchers as a valuable asset of volunteer's management. However, why people volunteer themselves remains an unsettled question, despite all the research carried out. ‘To analyse the profile of Food Bank volunteers, mostly regarding their motivation, generativity level and demographic characteristics’ was defined as the key objective for this research. For that purpose, the profile of volunteers belonging to two regional food banks was analysed. The motivational scale ‘Volunteer Functions Inventory’ and the ‘Loyola Generativity Scale’, were adopted for this research by means of a survey applied to 193 volunteers. According to the results achieved, the greater involved volunteers in the organization tend to be more orientated by social and altruistic motivations, the volunteer's generativity level is clearly related to the parenthood status of the volunteer and finally, the statistical analysis states that there is no relationship between the volunteers' level of education and his or her permanence in collaborating with the organization.Copyright © 2012 John Wiley & Sons, Ltd.
Surface modification of polyethylene by diffuse barrier discharge plasma
Authors: Novák Igor , Števiar Marian , Popelka Anton , Chodák Ivan , Mosnáček Jaroslav , Špírková Milena , Janigová Ivica , Kleinová Angela , Sedliačik Ján , Šlouf Miroslav 
Published: July 2012

AbstractLow‐density polyethylene (LDPE) modified by atmospheric dielectric surface barrier discharge plasma in oxygen was investigated to improve surface properties and adhesion of LDPE to more polar polymers. The process of plasma modification was investigated using several methods—surface energy measurements, Fourier Transform Infrared Spectroscopy with Attenuated Total Reflectance (FTIR‐ATR), Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM). The surface energy of LDPE increased significantly after activation by oxygen barrier plasma even at very short time of modification. The FTIR‐ATR spectra manifested the presence of carbonyl functional groups on the surface of polymer pre‐treated by oxygen barrier plasma. It was shown by SEM, and AFM, that the topography of modified LDPE was significantly changed and the surface of modified polymer exhibited higher roughness in comparison with unmodified polymer. The surface energy of treated LDPE diminished in the course of ageing especially during the first 10 days after modification by barrier plasma. Hydrophilicity of the modified LDPE surface was stabilized by photochemical post‐functionalization with 2,2,6,6‐tetramethylpiperidin‐4‐yl‐diazoacetate. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Serum zinc and prostate cancer risk in a nested case–control study: The multiethnic cohort
Authors: Park Song‐Yi , Wilkens Lynne R. , Morris J. Steven , Henderson Brian E. , Kolonel Laurence N. 
Published: July 2012

AbstractBACKGROUNDExperimental studies have provided evidence that zinc has a protective effect against development and progression of prostate cancer. However, epidemiological studies have reported inconsistent findings. We evaluated the association between prediagnostic serum zinc and prostate cancer risk in a cohort of multiethnic population.METHODSThis case–control study is nested within the Multiethnic Cohort of African Americans, Native Hawaiians, Japanese Americans, Latinos, and whites in Hawaii and California. The analysis included 392 prostate cancer cases and 783 controls matched on age, race/ethnicity, date/time of blood draw and fasting status. Conditional logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI).RESULTSThe mean serum zinc concentrations did not significantly differ between cases (94.9 µg/dl) and controls (93.9 µg/dl). No association was found between serum zinc levels and prostate cancer either overall or by tumor stage/grade. In ethnic‐specific analyses, positive associations were found in Japanese Americans (OR for the highest vs. the lowest tertile = 2.59, 95% CI: 1.09–6.17) and Latinos (OR = 2.74, 95% CI: 1.05–7.10), whereas no association was observed in African Americans and whites.CONCLUSIONSWe found no evidence to support an inverse relationship between serum zinc and prostate cancer risk, and, to the contrary, found a suggestion in the ethnic‐specific results of a possible increase in risk; however, blood concentrations of zinc may not adequately reflect the levels in prostate tissue. Further study with a larger sample size, and if possible, with assessment of zinc tissue levels, is warranted to confirm these findings. Prostate 73: 261–266, 2013. © 2012 Wiley Periodicals, Inc.
Occupational Characteristics, Occupational Sex Segregation, and Family Migration Decisions
Authors: Perales Francisco , Vidal Sergi 
Published: July 2012

ABSTRACTThis paper examines the effects of occupational characteristics on family migration within Britain. For the first time in the literature, we explicitly theorise and later test the impact of the sex composition of husbands' and wives' occupations on mobility decisions. The empirical analysis consists of panel regression models estimated on dyadic couple‐level information from the British Household Panel Survey combined with occupational‐level data from the UK Labour Force Survey. Results suggest that some occupational characteristics are significantly associated with family migration, whereas occupational sex segregation has limited impact. Although working in female‐dominated occupations is related to a lower propensity to become a lead mover and a higher propensity to become a tied mover, these associations are mediated by the socio‐economic and occupational characteristics of the spouses. Copyright © 2012 John Wiley & Sons, Ltd.
Colloidal TiO2 nanoparticles as substrates for M(S)ALDI mass spectrometry of transition metal complexes
Authors: Radisavljević Maja , Kamčeva Tina , Vukićević Iva , Radoičić Marija , Šaponjić Zoran , Petković Marijana 
Published: July 2012

RATIONALENanoparticles as substrates for matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS) have advantages over organic matrices, since they enable acquisition of spectra in the low‐mass range. It has been previously shown that TiO2 nanoparticles can be used as substrate for MALDI‐TOF MS analysis of phospholipids and for other types of molecules, but none of them was applied to the analysis of transition metal complexes.METHODSThe MALDI‐TOF mass spectra of potential anti‐tumor drugs [AuCl2(bipy)]Cl, [PtCl4(bipy)], and [RuCl2(bipy)2]Cl acquired with organic matrices have been compared with spectra acquired with colloidal titanium dioxide nanoparticles. Colloidal TiO2 nanoparticles (NPs) with average diameter of 5 nm were synthesized and characterized by microscopy. For some experiments, the TiO2 NPs were treated at 60 °C. Suspensions of matrix and the analyte were premixed, applied to the MALDI target and left at room temperature. Mass spectra were acquired with a 50‐Hz pulsed nitrogen laser emitting at a wavelength of 337 nm.RESULTSThe MALDI spectra of transition metal complexes acquired with TiO2 NPs exhibited somewhat lower sensitivity than those with organic matrices; on the other hand, they are characterized by significantly lower number of signals arising from the tested complexes than the organic matrices. Whereas adducts between organic matrices and the analytes were detectable in the spectra, this was not the case for the TiO2‐assisted mass spectra.CONCLUSIONSWe have shown that colloidal TiO2 NPs can be used as substrates for MALDI‐TOF MS of transition metal complexes. Although the sensitivity of this approach in comparison with the use of organic matrices might still be a problem, the potential of the applications of NPs for the mass spectrometric characterization of transition metal complexes is clearly demonstrated. Copyright © 2012 John Wiley & Sons, Ltd.