bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selective formation of novel fluorescent aggregates of rhodamine dyes: contribution of surface SiO2 layer and underlying Si layer
Authors: Tomioka Akihiro , Takeuchi Takaya , Takada Kouhei 
Published: October 2012

AbstractRhodamine (Rh) 6G aggregates were formed on a silicon substrate with a varying thickness surface SiO2 layer utilizing a dewetting process of Rh ethanol solution. Sufficient thickness of 30 nm SiO2 layer gave rise to fluorescent aggregates selectively, similar to those formed on a hydrophilic glass surface. Annealing at 200 oC forced a phase transition of those aggregates to fluorescence quenched state, which was also common with those formed on a hydrophilic glass surface. In contrast, sufficiently thin, e.g. naturally formed at ambient condition, 2 nm thick SiO2 layer gave rise to quenched aggregates, that was spectroscopically identical with the annealed aggregates formed on thick SiO2 layer. Whereas the quenching on sufficiently thin SiO2 layer may be partially due to a nonradiative energy transfer to underlying Si, the majority of the quenching was attributed to specific Rh molecular ordering that is thermodynamically stable than the quasi‐stable fluorescent Rh aggregates. This quasi‐stable aggregates were formed only on sufficiently thick SiO2 layer or on hydrophilic glass substrate. This finding will shed light on the disputed discrepancy of fluorescence quenching of Rh dyes deposited on SiO2 nanostripes that were formed on a Si substrate by local anodic oxidation using a conductive AFM tip. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Topological phase transition in bulk materials described by the coherent potential approximation technique
Authors: Chadov Stanislav , Kiss Janos , Kübler Jürgen , Felser Claudia 
Published: October 2012

Abstractmagnified imageWe consider the analogy between the topological phase transition which occurs on a surface of a non‐trivial insulator as a function of spatial coordinate, and the phase transition occurring in the bulk due to the change of internal parameters (such as crystal field and spin–orbit coupling). In both cases the system exhibits a Dirac cone, which is the universal manifestation of a topological phase transition, independent of the type of the driving parameters. In particular, this leads to a simple way of determining the topological class – based solely on the bulk information – even for systems where the translational symmetry is broken by atomic disorder or by strong electron correlations. Here we demonstrate this idea, using as an example the zinc‐blende related semiconductors by means of ab‐initio fully‐relativistic band structure calculations, involving the technique of coherent potential approximation (CPA). (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Observing electronic structures on ex‐situ grown topological insulator thin films
Authors: Yao S. H. , Zhou B. , Lu M. H. , Liu Z. K. , Chen Y. B. , Analytis J. G. , Brüne C. , Dang W. H. , Mo S.‐K. , Shen Z.‐X. , Fisher I. R. , Molenkamp L. W. , Peng H. L. , Hussain Z. , Chen Y. L. 
Published: October 2012

Abstractmagnified imageTopological insulators represent a new state of quantum matter recently discovered with insulating bulk but conducting surface states formed by an odd number of Dirac fermions. In this Letter, we report our recent progress on the study of electronic structures of ex‐situ grown topological insulator thin films by angle resolved photoemission spectroscopy (ARPES). We successfully obtained the topological band structures of molecular beam epitaxial HgTe and vapor–solid grown Bi2Te3 thin films after proper surface cleaning procedures. This new development will not only enable us to study more topological insulators that cannot be measured by conventional in‐situ ARPES technique (e.g. by cleaving or growing samples in‐situ), but also open the door to directly characterize the electronic properties of topological insulators used in functional devices. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Tensorial green‐function theory of atomic‐wire T‐junction transmission
Authors: Sulston Kenneth W. , Davison Sydney G. 
Published: October 2012

AbstractA tensorial Green‐function treatment of the electronic transmission properties of an atomic wire T‐junction is presented within the framework of the tight‐binding approximation. The adoption of the tensorial formalism enables overlap effects to be included in a straightforward manner, without the need to resort to a change in the Hilbert space. The T‐junction structure and the presence of overlap effects both give rise to antiresonances. Although those due to the former are located inside the energy band, the latter appear at the band edges. The transmission is seen to depend in different ways on the bond energy and the overlap between the attached atom and the wire. © 2012 Wiley Periodicals, Inc.
Gaussian basis sets for molecular applications
Authors: Hill J. Grant 
Published: October 2012

AbstractThe choice of basis set in quantum chemical calculations can have a huge impact on the quality of the results, especially for correlated ab initio methods. This article provides an overview of the development of Gaussian basis sets for molecular calculations, with a focus on four popular families of modern atom‐centered, energy‐optimized bases: atomic natural orbital, correlation consistent, polarization consistent, and def2. The terminology used for describing basis sets is briefly covered, along with an overview of the auxiliary basis sets used in a number of integral approximation techniques and an outlook on possible future directions of basis set design. © 2012 Wiley Periodicals, Inc.
Translation of real solid spherical harmonics
Authors: Rico Jaime Fernández , López Rafael , Ema Ignacio , Ramírez Guillermo 
Published: October 2012

AbstractGeneral formulae for the translation of both regular and irregular real solid harmonics are derived from the addition theorems of complex harmonics. The resultant expressions, being too complicated for practical purposes, are rewritten in a more compact and friendly manner. The usefulness of these simplified expressions is illustrated with two examples: the potential generated by sets of charges and multipoles in points placed far away, and the expansion in regular harmonics of the long‐range potential inside a region surrounded by pointwise charge distributions. © 2012 Wiley Periodicals, Inc.
Evaluation of electrospray ionisation mass spectrometry as a technique for the investigation of competitive interactions: A case study of the ternary Th‐Mn‐EDTA system
Authors: Reinoso‐Maset Estela , Worsfold Paul J. , Keith‐Roach Miranda J. 
Published: October 2012

RATIONALEElectrospray ionisation mass spectrometry (ESI‐MS) is a useful tool for exploring the speciation of solution‐phase metal complexes; however, the quantification of ternary systems is challenging due to the differences in the electrospray response of different species. Here, the Th‐Mn‐EDTA system was investigated to evaluate the capability of ESI‐MS for quantifying the species present.METHODSIncreasingly complex mixtures of Th(IV), Mn(II) and EDTA were analysed using manual flow injection of samples into an HPLC grade water mobile phase delivered to an ion trap mass spectrometer fitted with an ESI interface (ThermoQuest Finnigan Mat LCQ). Mass spectra were obtained in the positive and negative ion modes over a mass‐to‐charge (m/z) range from 50–2000.RESULTSThe instrumental response to EDTA was affected by the addition of Th(NO3)4 but not MnCl2, while the response to both Th‐EDTA and Mn‐EDTA species was affected by addition of the other metal salt. Internal standards were also found to suppress signals to different extents. Therefore, each signal suppression was carefully quantified as the solution became more complex, and signal correction factors were used in conjunction with regular external calibration. Mixed metal signals were quantified adequately.CONCLUSIONSThis study showed the complexity of quantifying a ternary system involving different co‐existing species. Nonetheless, the step‐wise protocol developed provided quantitative data on the displacement of Mn from its EDTA complex by Th. Copyright © 2012 John Wiley & Sons, Ltd.
Low Carbon High Nitrogen Low Nickel Stainless Steel
Authors: Ghali Saeed N. 
Published: October 2012

AbstractThis article aims to investigate the effect of soluble and insoluble nitrogen on mechanical properties of stainless steels. Reference steel contains about 14.42%Ni and 0.012%N. Two developed steels have the same base chemical composition of the reference steel except Ni and N contents. One of the developed steels has 6.54%Ni and 0.232%N and the other has 0.452%N and nearly nickel free (0.089%Ni). The produced steels were forged, heat‐treated, and tempered. The microstructure of steels was mainly austenite, and grain size decreases as nitrogen content – especially nitrides‐increases. Yield and ultimate tensile strength of reference steel are less than that of steels containing nitrogen. Strengthening mechanisms contribution to the strength of both soluble and insoluble nitrogen had been analyzed.
Synthesis and characterization of starch‐graft‐polyacrylamide copolymers and their application as filtration control agents in drilling fluid
Authors: Guo Wen‐Yu , Peng Bo 
Published: October 2012

AbstractSome starch‐graft‐polyacrylamide copolymers were prepared by the polymerization of corn starch with acrylamide in aqueous medium using a complex initiation system consisting of ceric ammonium sulphate and ammonium persulphate. The copolymers were applied to water‐based drilling fluid as filtration control agents. Their grafting parameters such as percentage of grafting, grafting efficiency, and solution viscosity (η) were investigated by using elemental analyzer and rotational viscometer. The results showed that increases in initiator concentration and reaction temperature first favored and then impeded the grafting reaction. Grafting of acrylamide onto starch increased with the increase of monomer concentration. It also increased with increasing reaction time up to a certain degree and then leveled off. For the graft copolymers, a higher percentage of grafting and higher η were beneficial in decreasing the filtrate volume of water‐based drilling fluid, even under an operating environments of 147°C and saturated salinity. A possible mechanism is proposed to interpret the improvement of fluid loss properties. J. VINYL ADDIT. TECHNOL., 2012. © 2012 Society of Plastics Engineers
Maximum product of effective channel gains: an innovative user selection algorithm for downlink multi‐user multiple input and multiple output
Authors: Shi Yuwei , Yu Qiyue , Meng Weixiao , Zhang Zhongzhao 
Published: October 2012

ABSTRACTRecently, zero‐forcing beamforming has been widely used for multiple‐input and multiple‐output broadcast channels, because it could provide suboptimal capacity with low complexity. To increase the sum data rate, a good user selection algorithm is attractive. In this paper, a new user selection algorithm named maximum product of effective channel gains is presented. The proposed algorithm is described mathematically, and the lower bound of the sum capacity is demonstrated to be proportional to the product of effective channel gains. Our simulation results show that maximum product of effective channel gains can achieve higher sum rate compared with the classical algorithm, semi‐orthogonal user selection, with the same complexity order, especially when the signal‐to‐noise ratio is high; in addition, the complexity of the proposed algorithm is superior to minimum of the Frobenius norm of the pseudo‐inverse algorithm. Meanwhile, the number of users that can be served simultaneously is equal to the number of transmission antennas, which is the maximum performance that can be achieved.Copyright © 2012 John Wiley & Sons, Ltd.
Ammonia toxicity to the brain
Authors: Braissant Olivier , McLin Valérie A. , Cudalbu Cristina 
Published: October 2012

AbstractHyperammonemia can be caused by various acquired or inherited disorders such as urea cycle defects. The brain is much more susceptible to the deleterious effects of ammonium in childhood than in adulthood. Hyperammonemia provokes irreversible damage to the developing central nervous system: cortical atrophy, ventricular enlargement and demyelination lead to cognitive impairment, seizures and cerebral palsy. The mechanisms leading to these severe brain lesions are still not well understood, but recent studies show that ammonium exposure alters several amino acid pathways and neurotransmitter systems, cerebral energy metabolism, nitric oxide synthesis, oxidative stress and signal transduction pathways. All in all, at the cellular level, these are associated with alterations in neuronal differentiation and patterns of cell death. Recent advances in imaging techniques are increasing our understanding of these processes through detailed in vivo longitudinal analysis of neurobiochemical changes associated with hyperammonemia. Further, several potential neuroprotective strategies have been put forward recently, including the use of NMDA receptor antagonists, nitric oxide inhibitors, creatine, acetyl‐L‐carnitine, CNTF or inhibitors of MAPKs and glutamine synthetase. Magnetic resonance imaging and spectroscopy will ultimately be a powerful tool to measure the effects of these neuroprotective approaches.
Chronic administration of branched‐chain amino acids impairs spatial memory and increases brain‐derived neurotrophic factor in a rat model
Authors: Scaini Giselli , Comim Clarissa M. , Oliveira Giovanna M. T. , Pasquali Matheus A. B. , Quevedo João , Gelain Daniel P. , Moreira José Cláudio F. , Schuck Patrícia F. , Ferreira Gustavo C. , Bogo Maurício R. , Streck Emilio L. 
Published: October 2012

AbstractMaple syrup urine disease (MSUD) is a neurometabolic disorder that leads to the accumulation of branched‐chain amino acids (BCAAs) and their α‐keto branched‐chain by‐products. Because the neurotoxic mechanisms of MSUD are poorly understood, this study aimed to evaluate the effects of chronic administration of a BCAA pool (leucine, isoleucine and valine). This study examined the effects of BCAA administration on spatial memory and the levels of brain‐derived neurotrophic factor (BNDF). We examined both pro‐BDNF and bdnf mRNA expression levels after administration of BCAAs. Furthermore, this study examined whether antioxidant treatment prevented the alterations induced by BCAA administration. Our results demonstrated an increase in BDNF in the hippocampus and cerebral cortex, accompanied by memory impairment in spatial memory tasks. Additionally, chronic administration of BCAAs did not induce a detectable change in pro‐BDNF levels. Treatment with N‐acetylcysteine and deferoxamine prevented both the memory deficit and the increase in the BDNF levels induced by BCAA administration. In conclusion, these results suggest that when the brain is chronically exposed to high concentrations of BCAA (at millimolar concentrations) an increase in BDNF levels occurs. This increase in BDNF may be related to the impairment of spatial memory. In addition, we demonstrated that antioxidant treatment prevented the negative consequences related to BCAA administration, suggesting that oxidative stress might be involved in the pathophysiological mechanism(s) underlying the brain damage observed in MSUD.
Expression of the Nrf2‐system at the blood‐CSF barrier is modulated by neonatal inflammation and hypoxia‐ischemia
Authors: D'Angelo Barbara , Ek C. Joakim , Sandberg Mats , Mallard Carina 
Published: October 2012

AbstractTranscription factor NF‐E2‐related factor‐2 (Nrf2) is a key regulator of endogenous anti‐oxidant systems shown to play a neuroprotective role in the adult by preserving blood–brain barrier function. The choroid plexus, site for the blood‐CSF barrier, has been suggested to be particularly important in maintaining brain barrier function in development. We investigated the expression of Nrf2‐ and detoxification‐system genes in choroid plexus following systemic LPS injections, unilateral cerebral hypoxia‐ischemia (HI) as well as the combination of LPS and HI (LPS/HI). Plexuses were collected at different time points after LPS, HI and LPS/HI in 9‐day old mice. mRNA levels of Nrf2 and many of its target genes were analyzed by quantitative PCR. Cell death was analyzed by caspase‐3 immunostaining and TUNEL. LPS caused down‐regulation of the Nrf2‐system genes while HI increased expression at earlier time points. LPS exposure prior to HI prevented many of the HI‐induced gene increases. None of the insults resulted in any apparent cell death to choroidal epithelium. These data imply that the function of the inducible anti‐oxidant system in the choroid plexus is down‐regulated by inflammation, even if choroid cells are not structurally damaged. Further, LPS prevented the endogenous antioxidant response following HI, suggesting the possibility that the choroid plexus may be at risk if LPS is united with an insult that increases oxidative stress such as hypoxia‐ischemia.
Optimize radiochemotherapy in pancreatic cancer: PARP inhibitors a new therapeutic opportunity
Authors: Porcelli Letizia , Quatrale Anna E. , Mantuano Paola , Leo Maria G. , Silvestris Nicola , Rolland Jean F. , Carioggia Enza , Lioce Marco , Paradiso Angelo , Azzariti Amalia 
Published: October 2012

Cancer cells may use PARP enzymes and Homologous Recombination to repair single and double strand breaks caused by genotoxic insults. In this study, the PARP‐1 inhibitor Rucaparib was utilized to increase the sensitivity to chemoradiotherapy treatment in BRCA‐2‐deficient and ‐proficient pancreatic cancer cells. We used the pancreatic cancer cell lines, Capan‐1 with mutated BRCA‐2 and Panc‐1, AsPC‐1 and MiaPaCa‐2 with BRCA‐1/2 wild type. Cells were treated with Rucaparib and/or radiotherapy (4–10 Gy) plus Gemcitabine then the capability to proliferate was evaluated by colony formation, cell counting and MTT assays. Flow cytometry, immunocytochemistry and western blotting were utilized to assess cell response to Rucaparib plus irradiation. The antitumour effectiveness of combining the PARP‐1 inhibitor before, together and after radiotherapy evidenced the first as the optimal schedule in blocking cell growth. Pre‐exposure to Rucaparib increased the cytotoxicity of Gemcitabine plus radiotherapy by heavily inducing the accumulation of cells in G2/M phase, impairing mitosis and finally inducing apoptosis and authophagy. The upregulation of p‐Akt and downregulation of p53 were evidenced in MiaPaCa‐2 which displayed replication stress features. For the first time, the rationale of using a PARP inhibitor as chemoradiosensitizer in pancreatic cancer models has been hypothesized and demonstrated.
Silicified serpentinite – a residuum of a Tertiary palaeo-weathering surface in the United Arab Emirates
Authors: LACINSKA ALICJA M. , STYLES MICHAEL T. 
Published: October 2012

AbstractMineralogical studies of a silicified serpentinite from the United Arab Emirates throw light on the formative processes. The silicified serpentinite is a residuum of a palaeo-weathering surface that probably developed in a temperate climate with alternating wet and dry periods during middle Eocene to late Miocene times. The rock textures indicate that silicification occurred in a fluid-saturated zone. Silica precipitation is favoured at near-neutral pH. In this study we infer that these pH conditions of the mineralizing fluids could arise in a near-surface mixing zone where acidic meteoric and hyperalkaline groundwater fluids are mingled. This mingling is believed to have resulted from alternating processes of evaporation and precipitation that prevailed during dry and wet seasons, respectively. The silicified serpentinite is composed of > 95% quartz and exhibits a ghost texture of the protolith serpentinite. Preservation of the textures indicates an iso-volumetric grain-by-grain replacement by dissolution of Mg-silicate and simultaneous precipitation of either opal or microquartz as siliceous seeds. These were subsequently overgrown by silica that was probably remobilized from deeply weathered regolith elsewhere.
A revised sedimentary and biostratigraphical architecture for the Type Llandovery area, Central Wales
Authors: DAVIES JEREMY R. , WATERS RICHARD A. , MOLYNEUX STEWART G. , WILLIAMS MARK , ZALASIEWICZ JAN A. , VANDENBROUCKE THIJS R. A. , VERNIERS JACQUES 
Published: October 2012

AbstractThe global standard for the Llandovery Series (early Silurian) in central Wales is re-assessed in the light of detailed geological surveying, biostratigraphical sampling and a rigorous examination of published datasets. A new sedimentary and biostratigraphical architecture is presented. Key graptolite, brachiopod, acritarch and, for the first time, chitinozoan assemblages are critically assessed. Upper Hirnantian to Aeronian strata record events that followed the Late Ordovician glacial maximum and comprise a series of progradational sequences bounded by flooding surfaces, but inferred still to be glacioeustatic in origin. Significant faunal renewals associated with many of the flooding levels underpin their potential for international recognition. Compound non-sequences are a feature of proximal parts of the system where erosion associated with fault footwall uplift was an important process. Extensive slump sheets contribute to further stratal loss and displacement in distal facies. A re-assessment of the Aeronian Stage GSSP reveals shortcomings with the biostratigraphical criteria used in its selection. Telychian portions of the succession display the disrupting effects of intra-Wenlock synsedimentary sliding; hence the relevance of key published fossil assemblages and the criteria used to erect the stage GSSP are undermined. However, the Llandovery area remains one of the best studied early Silurian successions in the world. This, together with regional considerations, supports the retention of the series standard in mid Wales where the contiguous deep-water basinal succession affords internationally cited exposure of richly graptolitic facies for the whole series and, significantly, for the post-sedgwickiiBiozone interval.
Remnant fragments within an agricultural matrix enhance conditions for a rodent host and its fleas
Authors: VAN DER MESCHT LUTHER , LE ROUX PETER C. , MATTHEE SONJA 
Published: October 2012

SUMMARYHabitat fragmentation can adversely impact biodiversity, although where remnant fragments of natural vegetation provide favourable conditions the negative effects of fragmentation may be mitigated. Host-parasite systems in fragmented areas have only recently been examined, with parasites generally showing higher prevalence and richness in fragments, mediated by changes in host density. However, the effect of fragmentation on parasite body size and fecundity remains poorly investigated. Thus, here we compared the body size and condition of a generalist rodent host,Rhabdomys pumilioand the body size of 2 common flea species between pristine natural areas and remnant fragments within agriculture areas. Host body length, weight and body condition values were significantly larger in fragments than in pristine natural vegetation.Listropsylla agrippinaefleas showed the same pattern, being significantly larger in fragments, whileChiastopsylla rossifleas did not differ in size between fragments and natural areas. The differential response of the 2 flea species may reflect the strength of association between the host and parasite, with the former spending a greater proportion of its lifespan on the host. Therefore, in this study agriculture fragments provide better conditions for both an opportunistic rodent and a closely associated flea species.