bluuebunny/crossref_metadata_2025_split huggingface dataset:
Extruder‐made TPO nanocomposites. I. Effect of maleated polypropylene and organoclay ratio on the morphology and mechanical properties
Authors: Tiwari Rajkiran R. , Hunter Douglas L. , Paul Donald R. 
Published: September 2012

AbstractPP/PP‐g‐MA/MMT/EOR blend nanocomposites were prepared in a twin‐screw extruder at fixed 30 wt % elastomer and 0 to 7 wt % MMT content. Elastomer particle size and shape in the presence of MMT were evaluated at various PP‐g‐MA/organoclay masterbatch ratios of 0, 0.5, 1.0, and 1.5. The organoclay dispersion facilitated by maleated polypropylene serves to reduce the size of the elastomer dispersed phase particles and facilitates toughening of these blend nanocomposites. The rheological data analysis using modified Carreau‐Yasuda model showed maximum yield stress in extruder‐made nanocomposites compared with nanocomposites of reactor‐made TPO. Increasing either MMT content or the PP‐g‐MA/organoclay ratio can drive the elastomer particle size below the critical particle size below which toughness is dramatically increased. The ductile‐brittle transition shift toward lower MMT content as the PP‐g‐MA/organoclay ratio is increased. The D‐B transition temperature also decreased with increased MMT content and masterbatch ratio. Elastomer particle sizes below ∼1.0 μm did not lead to further decrease in the D‐B transition temperature. The tensile modulus, yield strength, and elongation at yield improved with increasing MMT content and masterbatch ratio while elongation at break was reduced. The modified Mori‐Tanaka model showed better fit to experimental modulus when the effect of MMT and elastomer are considered individually. Overall, extruder‐made nanocomposites showed balanced properties of PP/PP‐g‐MA/MMT/EOR blend nanocomposites compared with nanocomposites of reactor‐made TPO. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012
Electrical and optical simulations of a polymer‐based phosphorescent organic light‐emitting diode with high efficiency
Authors: Al‐Sa'di Mahmoud , Jaiser Frank , Bagnich Sergey , Unger Thomas , Blakesley James , Wilke Andreas , Neher Dieter 
Published: September 2012

AbstractA comprehensive numerical device simulation of the electrical and optical characteristics accompanied with experimental measurements of a new highly efficient system for polymer‐based light‐emitting diodes doped with phosphorescent dyes is presented. The system under investigation comprises an electron transporter attached to a polymer backbone blended with an electronically inert small molecule and an iridium‐based green phosphorescent dye which serves as both emitter and hole transporter. The device simulation combines an electrical and an optical model. Based on the known highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels of all components as well as the measured electrical and optical characteristics of the devices, we model the emissive layer as an effective medium using the dye's HOMO as hole transport level and the polymer LUMO as electron transport level. By fine‐tuning the injection barriers at the electron and hole‐injecting contact, respectively, in simulated devices, unipolar device characteristics were fitted to the experimental data. Simulations using the so‐obtained set of parameters yielded very good agreement to the measured current–voltage, luminance–voltage characteristics, and the emission profile of entire bipolar light‐emitting diodes, without additional fitting parameters. The simulation was used to gain insight into the physical processes and the mechanisms governing the efficiency of the organic light‐emitting diode, including the position and extent of the recombination zone, carrier concentration profiles, and field distribution inside the device. The simulations show that the device is severely limited by hole injection, and that a reduction of the hole‐injection barrier would improve the device efficiency by almost 50%. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012
Structural and chemical characterization of nanocrystalline and amorphous hydrogenated Si films
Authors: Garozzo Cristina , Puglisi Rosaria Anna , Lombardo Salvatore 
Published: September 2012

AbstractWe present a study on the morphological evolution of hydrogenated amorphous silicon layers obtained by plasma enhanced chemical vapor deposition at different H dilutions in the regime close to the formation of the nanocrystalline (nc‐Si) phase. The role of hydrogen in the transition from the amorphous to the crystalline phase is investigated by accurate structural and chemical characterisation, from the early stages of nucleation, where the nuclei present a size slightly larger than the critical nucleus, i.e. about 0.8 nm in radius, up to the formation of crystalline grains larger than 30 nm in radius. Hydrogen is found to have a crucial role in the transition from a‐Si:H to nc‐Si:H, since it forms an intermediate bond‐centred Si–H–Si configuration, and when the H moves away from the bond‐centred location, the strained Si–Si bonds either break or relax, undergoing local structural rearrangements closer to those of c‐Si. During this phase transition a part of H bonds at grain boundaries. A correlation between the structural characteristics of the crystalline phase and the bonding mechanism of Si with H through multiple hydrides, such as Si‐H2 and Si‐H3 is found. Particularly the SiH3 are found to be directly correlated to the shape and the size of the nanocrystallites present in the films (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Robust and Aligned Carbon Nanotube/Titania Core/Shell Films for Flexible TCO‐Free Photoelectrodes
Authors: Di Jiangtao , Yong Zhenzhong , Yao Zhaojun , Liu Xiangyang , Shen Xiaojuan , Sun Baoquan , Zhao Zhigang , He Huixin , Li Qingwen 
Published: September 2012

AbstractCarbon nanotube (CNT)/semiconducting oxide hybrids are an ideal architecture for light‐harvesting devices, in which the CNTs are expected to not only act as a scaffold but also provide fast transport paths for photogenerated charges in the oxide. However, the current potential of CNTs for charge transport is largely suppressed due to the nanotubes not being interconnected but isolated by the low conductive oxide coatings. Herein, a flexible and conductive CNT/TiO2 core/shell heterostructure film is reported, with aligned and interconnected CNTs wrapped in a continuous TiO2 coating. Without using additional transparent conducting oxide (TCO) substrates, this unique feature of the film boosts the incident photon‐to‐electron conversion efficiency to 32%, outperforming TiO2 nanoparticle electrodes fabricated on TCO substrates. Moreover, the film shows high structural stability and can generate a stable photocurrent even after being bent hundreds of times.
Thermal Decomposition Reactions for the Exploration of New Coordination Polymers based on Mn(NCS)2 and Pyridazine
Authors: Wöhlert Susanne , Näther Christian 
Published: September 2012

AbstractReaction of different ratios of manganese(II) thiocyanate with pyridazine in water at room temperature leads always to the formation of the pyridazine‐rich 1:4 compound (1:4 = ratio between metal and neutral co‐ligand) Mn(NCS)2(pyridazine)4 (1). In the crystal structure of 1, the Mn2+ cations are coordinated by two nitrogen atoms of terminal N‐bonded thiocyanato anions and four nitrogen atoms of pyridazine ligands within slightly distorted octahedra. However, in one reaction single crystals of the new compound Mn3(NCS)6(pyridazine)4(H2O)·(pyridazine) (2) were obtained. In its crystal structure the manganese atoms are linked into chains by µ‐1, 3 and µ‐1, 1 bridging thiocyanato anions as well as bridging pyridazine ligands. Heating rate dependent DTA‐TG measurements of 1 reveal a multi‐step thermal decomposition, in which three new pyridazine‐deficient compounds of composition Mn(NCS)2(pyridazine)3 (3), Mn(NCS)2(pyridazine)2 (4) and Mn(NCS)2(pyridazine) (5‐Mn) are formed. IR‐spectroscopic investigations indicate that on heating more condensed coordination networks with µ‐1, 3‐ and µ‐1, 1‐bridging thiocyanato anions has formed. Magnetic measurements show only Curie‐Weiss paramagnetism for compounds 1, 3 and 4, whereas in the 1:1 compound 5 an antiferromagnetic ordering is observed at TN = 14 K. Surprisingly, the most pyridazine deficient compound 5 transforms into 2 after storage for several weeks.
(NH4)AgMoS4: Synthesis, Structure and Catalytic Activity
Authors: Shafaei‐Fallah Maryam , Malliakas Christos D. , Kanatzidis Mercouri G. 
Published: September 2012

AbstractThe synthesis, characterization and crystal structure of (NH4)AgMoS4 is presented. (NH4)AgMoS4 was prepared by the stoichiometric reaction of AgNO3 with (NH4)2MoS4. The black microcrystalline (NH4)AgMoS4 is thermally unstable and contaminated by a phase that analyzes for Ag2MoS4. In the TGA continuous weight loss was observed corresponding to the loss of ammonia gas subsequent loss of sulfur and H2S to give Ag2S and MoS2. In the infrared spectrum of (NH4)AgMoS4, characteristic bands for the ammonium ion at 1350–1400 cm–1 and for the [MoS4]2– group at 460 cm–1 are observed. Crystals of (NH4)AgMoS4 were investigated using a synchroton source. (NH4)AgMoS4 is isostructural to (NH4)CuMoS4 and crystallizes in the tetragonal space group I$\bar{4}$ (Z = 2, a = 7.8740(3), c = 5.7733(4) Å). (NH4)AgMoS4 can be used as a catalyst in the syngas conversion to higher alcohols with showing good activity and ethanol selectivity.
Origins for Everyone
Authors: Ellington Andrew D. 
Published: September 2012

Abstract
The origin of life on Earth remains a mystery, but the question can still be approached with scientific rigor. Identifying life’s origins requires the definition of life itself, which has been described as a self-sustaining system capable of Darwinian evolution, although it's also possible that there is no good scientific definition. All known living systems contain linear strings of information based on DNA, a molecule that makes Darwinian evolution possible through replication and mutation. This review explains the scientific concepts and issues underlying the origin of life, possible mechanisms of origins, and the features of living systems that can arguably be viewed as an inevitable consequence of the earliest molecules.
Morphologic changes in the placentas of HIV‐positive women and their association with degree of immune suppression
Authors: Vermaak Anine , Theron Gerhard B. , Schubert Pawel T. , Kidd Martin , Rabie Ursula , Adjiba Benedict M. , Wright Colleen A. 
Published: September 2012

AbstractObjectiveTo provide baseline information regarding a possible association between specific histopathologic features of the placentas of HIV‐positive women and the degree of immune suppression.MethodsA prospective single‐blinded laboratory‐based pilot study was conducted at Tygerberg Hospital, South Africa. The macroscopic and microscopic features of placentas from HIV‐positive (n = 91) and HIV‐negative women (n = 89) were compared and recorded using a standard template. Investigators were blinded to the participants’ HIV status and CD4‐positive cell count.ResultsPlacentas from the HIV‐positive group were characterized by decreased weight and increased number of marginal infarcts relative to the HIV‐negative group. The most important microscopic finding was the increased presence of villitis of unknown etiology (VUE) among the group of untreated HIV‐positive women with CD4 cell counts of 200 cells/mm3 or below.ConclusionBoth macroscopic and microscopic differences relating to the degree of immune suppression were identified, which seemingly contradicts previous reports. Larger studies are warranted to define the function of antiretroviral therapy and VUE in the mechanism of mother‐to‐fetus transmission of HIV. Furthermore, the potential role of VUE in the pathophysiology of the compromised immune response observed among HIV‐exposed but uninfected infants should be investigated.
Misoprostol for preventing and treating postpartum hemorrhage in the community: A closer look at the evidence
Authors: Oladapo Olufemi T. 
Published: September 2012

AbstractThe lack of clear interpretation of clinical and operational evidence on misoprostol use for postpartum hemorrhage (PPH) in the community may jeopardize the realization of its full potential for improving women's survival. This paper highlights the usefulness of misoprostol in addressing PPH in the community within the limits of available research evidence. There is now substantial evidence to support the beneficial effects of 600 μg of oral misoprostol for PPH prevention in the community, with a trend toward better protection against severe PPH morbidity, and particularly when administered by less skilled or lay caregivers. Although there is tangible evidence to show that 800 μg of sublingual misoprostol has important benefits for PPH treatment where there is no access to oxytocin, there is presently no direct evidence to indicate that less skilled or lay caregivers can safely use it to treat PPH in the community. Operational research evidence indicates that advance community distribution of misoprostol to pregnant women for postpartum self‐use is a feasible strategy to ensure availability of the drug at the time of birth. The evidence is, however, limited by its quality to establish whether the benefits of such a strategy truly outweigh the potential harms. It is time for the international community to focus on improving PPH‐related outcomes by scaling up what is currently guided by hard evidence and join forces to address unanswered questions through high‐quality research.
Major hydrological regime change along the semiarid western coast of South America during the early Holocene
Authors: Ortega Cristina , Vargas Gabriel , Rutllant José A. , Jackson Donald , Méndez César 
Published: September 2012

AbstractWater availability in the semiarid western coast of Chile (30–32°S) is conditioned by high interannual precipitation variability, reflecting the transition between arid subtropical and moist mid-latitude climates in the Southeastern Pacific Ocean. A paleoclimate reconstruction based on the latest Pleistocene–Holocene geological record from the Quebrada Santa Julia archeological site in Chile (31°50′S) and on modern meteorological mechanisms producing alluvial episodes in this region indicates a major change in the rainfall regime shortly after 8600 cal yr BP. This, together with other paleoclimate proxies along the west coast of South America (34°–14°S), suggests La Niña-like conditions 13,000–8600 cal yr BP. Based on sedimentological and geomorphologic evidence, we hypothesized that the absence of heavy rainfall events in northern Chile and the new hydrological regime that prevailed ca. 8600–5700 cal yr BP in north-central Chile resulted from an increase in the large-scale westerly flow over central Chile, as expected in near-neutral ENSO conditions. This atmospheric circulation anomaly is compatible with an equatorward shift of the influence of the Southeast Pacific Subtropical Anticyclone relative to the early Holocene, prior to the onset of modern ENSO variability.
Readmission of known MRSA carriers and MRSA colonization pressure in hospital
Authors: GROHS P. , PINEAU B. , KAC G. , GUTMANN L. , MEYER G. 
Published: September 2012

SUMMARYReadmission of asymptomatic methicillin-resistant Staphylococcus aureus (MRSA) carriers may contribute to the hospital reservoir. Using an electronic alert system, we assessed the weight of readmission of known MRSA carriers on MRSA colonization pressure in a hospital setting. During the 2004–2010 period, 2058 alerts were generated for 1060 inpatients. A total of 486/1060 patients (46%) were readmitted at least once, and 330/486 (64·4%) were readmitted <3 months after discharge. A mean of 20 MRSA patients were present on the same day (from 40 in 2004 to eight in 2010). The number of MRSA patient-days was 34 575, i.e. 2·5% of the 1 366 277 patient-days of the study period, and 17 737 (51·3%) MRSA patient-days were due to readmission of known MRSA carriers. The number of new MRSA cases was partly correlated with the number of MRSA patients hospitalized (R2 = 0·49). Rapid electronic identification of these patients proved essential in decreasing the global burden of MRSA in our hospital.
Hepatitis C virus prevalence in The Netherlands: migrants account for most infections
Authors: VRIEND H. J. , VAN VEEN M. G. , PRINS M. , URBANUS A. T. , BOOT H. J. , OP DE COUL E. L. M. 
Published: September 2012

SUMMARYA population-based anti-hepatitis C virus (HCV) prevalence is important for surveillance purposes and it provides insight into the burden of disease. The outcomes of recent studies in the general Dutch population as well as recent HCV data from specific risk groups including migrants, men who have sex with men (MSM) and injecting drug users (IDUs), were implemented in a modified version of the Workbook Method (a spreadsheet originally designed for HIV estimations), to estimate Dutch HCV seroprevalence. The estimated national seroprevalence of HCV was 0·22% (min 0·07%, max 0·37%), corresponding to 28 100 (min n = 9600, max n = 48 000) HCV-infected individuals in The Netherlands. Of these, first-generation migrants from HCV-endemic countries (HCV prevalence ⩾2%) accounted for the largest HCV-infected group, followed by IDUs and HIV-positive MSM.
A randomized, double-blind, placebo-controlled 6-wk trial of the efficacy and tolerability of 5 mg vortioxetine in adults with major depressive disorder*
Authors: Jain Rakesh , Mahableshwarkar Atul R. , Jacobsen Paula L. , Chen Yinzhong , Thase Michael E. 
Published: September 2012

Abstract
Vortioxetine (Lu AA21004) is a multi-modal antidepressant in clinical development for the treatment of major depressive disorder (MDD). The current study evaluated the efficacy and tolerability of 5 mg vortioxetine compared to placebo after 6 wk of treatment in adults with MDD in an out-patient setting. Adults aged 18–75 yr, with a diagnosis of MDD and a baseline Montgomery–Asberg Depression Rating Scale (MADRS) total score ⩾30, were randomized to receive either 5 mg vortioxetine or placebo over 6 wk, followed by a 2-wk medication-free discontinuation period. The primary efficacy measure was change from baseline in Hamilton Rating Scale for Depression (HAMD)-24 total score at week 6 compared to placebo. Additional measures included response and remission rates, Clinical Global Impression Scale – Improvement scores, HAMD-24 total score in subjects with baseline Hamilton Anxiety Scale (HAMA) >19 and MADRS-S total score. Adverse events (AEs) were assessed throughout the study. A total of 600 adults were randomized. There were no significant differences in efficacy measures between subjects in the 5 mg vortioxetine and placebo groups at week 6. HAMD-24 total score in subjects with baseline HAMA >19 in the 5 mg vortioxetine group was improved at weeks 3–6 compared to the placebo group (nominal p value <0.05). The most common AEs for the vortioxetine and placebo groups were nausea (19.1 and 9.4%), headache (17.1 and 15.1%) and diarrhoea (11.4 and 7.0%), respectively. In this study of adults with MDD, 5 mg vortioxetine did not differ significantly from placebo in reducing depression symptoms after 6 wk of treatment.
Cyclin-dependent kinase-5 and p35/p25 activators in schizophrenia and major depression prefrontal cortex: basal contents and effects of psychotropic medications
Authors: Ramos-Miguel Alfredo , Meana J. Javier , García-Sevilla Jesús A. 
Published: September 2012

AbstractCyclin-dependent kinase-5 (CDK5) and p35/p25 activators, interacting with the exocytotic machinery (e.g. munc18-1 and syntaxin-1A), play critical roles in neurosecretion. The basal status of CDK5/p35/p25 and the effect of psychotropic drugs (detected in blood/urine samples) were investigated in post-mortem prefrontal cortex (PFC)/Brodmann's area 9 of schizophrenia (SZ) and major depression (MD) subjects. In SZ (all subjects, n = 24), CDK5 and p35, but not p25, were reduced (−28 to −58%) compared to controls. In SZ antipsychotic-free (n = 12), activator p35 was decreased (−52%). In SZ antipsychotic-treated (n = 12), marked reductions of CDK5 (−47%), p35 (−76%) and p25 (−36%) were quantified. In MD (n = 13), including antidepressant-free/treated subgroups, CDK5, p35 and p25 were unaltered. In SZ (n = 24), CDK5, p35 or p25 correlated with munc18-1a, but not with syntaxin-1A. The results demonstrate reduced p35 basal content and down-regulation of CDK5/p35/p25 by antipsychotics in SZ. The suggested CDK5/munc18-1a functional interaction may lead to dysregulated neurosecretion in SZ PFC.
The structure, dynamics and tropospheric signature of the Polar Annular Mode
Authors: Black Robert X. , McDaniel Brent , Lee Yun‐Young 
Published: September 2012

Intraseasonal variability in the stratospheric polar vortex is intrinsically linked to concomitant tropospheric variability via the annular modes. The primary mode, the Northern Annular Mode (NAM), represents variability in the polar vortex strength while the second mode, the lesser studied Polar Annular Mode (PAM), represents variability in the latitudinal position of the polar vortex. The current study examines the structural evolution, zonal‐mean dynamical forcing and tropospheric impact of discrete PAM episodes occurring during boreal winter. The analysis identifies large amplitude positive and negative PAM events occurring in the absence of NAM or sudden stratospheric warming events. Composite time evolution analyses are performed for both positive and negative PAM events. The onset of positive (negative) PAM events is preceded by a weak and broad acceleration (deceleration) within the stratospheric polar vortex at midlatitudes. During PAM onset the canonical PAM structure in zonal‐mean zonal wind develops over a 5 day period in association with robust stratosphere‐troposphere coupling. Zonal wind changes occurring during onset are induced by anomalous wave driving associated with low frequency Rossby wave activity. After PAM onset, the zonal wind anomaly features at high latitudes quickly weaken while those in the subtropics and midlatitudes persist for a period of 2–3 weeks. During this time, PAM events provide a statistically significant impact upon the tropospheric circulation, with large‐scale perturbations in (a) surface air temperature over North America and Eurasia and (b) the structure and amplitude of the primary storm tracks.
Climatology of midlatitude ionospheric disturbances from the Very Large Array Low‐frequency Sky Survey
Authors: Helmboldt J. F. , Lane W. M. , Cotton W. D. 
Published: September 2012

The results of a climatological study of ionospheric disturbances derived from observations of cosmic sources from the Very Large Array (VLA) Low‐frequency Sky Survey (VLSS) are presented. We have used the ionospheric corrections applied to the 74 MHz interferometric data within the VLSS imaging process to obtain fluctuation spectra for the total electron content (TEC) gradient on spatial scales from a few to hundreds of kilometers and temporal scales from less than one minute to nearly an hour. The observations sample nearly all times of day and all seasons. They also span latitudes and longitudes from 28°N to 40°N and 95°W to 114°W, respectively. We have binned and averaged the fluctuation spectra according to time of day, season, and geomagnetic (Kp index) and solar (F10.7) activity. These spectra provide a detailed, multiscale account of seasonal and intraday variations in ionospheric activity with wavelike structures detected at wavelengths between about 35 and 250 km. In some cases, trends between spectral power and Kp index and/or F10.7 are also apparent. In addition, the VLSS observations allow for measurements of the turbulent power spectrum down to periods of 40 s (scales of ∼0.4 km at the height of the E‐region). While the level of turbulent activity does not appear to have a strong dependence on eitherKp index or F10.7, it does appear to be more pronounced during the winter daytime, summer nighttime, and near dusk during the spring.