bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multiple dark matter as a self‐regulating mechanism for dark sector interactions
Authors: Baldi M. 
Published: July 2012

AbstractA wide range of astrophysical and cosmological observations support the evidence that the energy density of the Universe is presently largely dominated by particles and fields that do not belong to the standard model of particle physics. Such cosmic dark sector appears to be made of two distinct entities capable to account for the growth of large‐scale structures and for the observed acceleration of the expansion rate of the Universe, respectively dubbed dark matter and dark energy. Nevertheless, the fundamental nature of these two dark components has so far remained mysterious. In the currently accepted scenario dark matter is associated to a single new massive and weakly interacting particle beyond the standard model, while dark energy is assumed to be a simple cosmological constant. However, present cosmological constraints and the absence of a direct detection and identification of any dark matter particle candidate leave room to the possibility that the dark sector of the Universe be actually more complex than it is normally assumed. In particular, more than one new fundamental particle could be responsible for the observed dark matter density in the Universe, and possible new interactions between dark energy and dark matter might characterize the dark sector. In the present work, the possibility that two dark matter particles may exist in nature is investigated. These different species are assumed to have identical physical properties except for the sign of their coupling constant to dark energy. Extending previous works on similar scenarios, the evolution of the background cosmology as well as the growth of linear density perturbations for a wide range of parameters of such multiple dark matter model is studied. Interestingly, the results show how the simple assumption that dark matter particles carry a “charge” with respect to their interaction with the dark energy field allows for new long‐range scalar forces of gravitational strength in the dark sector without conflicting with present observations both at the background and linear levels. The presented scenario does not introduce new parameters with respect to the case of a single dark matter species for which such strong dark interactions have been already ruled out. Therefore, the present investigation suggests that only a detailed study of nonlinear structure formation processes might possibly provide effective constraints on new scalar interactions of gravitational strength in the dark sector.
Protein folding – simplicity in complexity
Authors: Lin M.M. , Zewail A.H. 
Published: July 2012

AbstractUnderstanding and predicting protein folding would elucidate how misfolded proteins cause aggregation and amyloid formation, for example in Alzheimer's disease. Despite the seemingly bewildering complexity of protein biology, simple analytic models can still capture the basic physics and predict the fundamental limits for protein domain size and folding speed.
Improving the flame retardancy of the polypropylene/aramid fiber composites by the introduction of decabromodiphenyl ethane and antimony trioxide
Authors: Chen Xiao‐Sui , Xu Guo‐Zhi , Zhang Sheng , Zhang Rong , Sun Jun , Dong Ming‐Zhe , Zhu Xin‐Jun , Liu Wei 
Published: July 2012

AbstractOur previous study showed that aramid fibers (AFs) could significantly enhance the mechanical properties of polypropylene (PP) composites; for example, the tensile strength of PP/AF composites with 30 wt % AF increased by 65.6%, whereas the Izod notched impact strength was almost five times that of pure PP. However, the fire performance of the PP/AF composites was not ideal. In this study, decabromodiphenyl ethane and antimony trioxide [Sb2O3; decabromodiphenyl ethane–antimony trioxide (D–S)] were introduced to improve the flame retardancy of PP/D–S/AF composites. Fourier transform infrared spectroscopy and scanning electron microscopy techniques were used to investigate the possible chemical reaction between the phosphate coupling agent and AFs. The mechanical properties of the PP composites were evaluated by tensile, flexural, and impact tests. The flame retardancy was characterized by limiting oxygen index and UL‐94 burning tests. The thermal properties of the PP composites was also investigated by combined thermogravimetry–differential thermal analysis. The results show that good interfacial adhesion between the fibers and the PP matrix was formed in the presence of the phosphate coupling agent. The flame retardancy and mechanical properties of the PP/D–S/AF composites were significantly improved by the incorporation of AFs and D–S. The sample containing 30 wt % D–S and 20 wt % AF reached V‐0 in the UL‐94 test. The maximal char residue of PP/D–S/AF was up to 15.5%, which was 115% higher than that of PP/D–S. A possible synergism of the flame retardancy between the AFs and D–S is proposed and discussed. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Alignment and properties of carbon nanotube buckypaper/liquid crystalline polymer composites
Authors: Chang Chi‐Yung , Phillips Erin M. , Liang Richard , Tozer Stanley W. , Wang Ben , Zhang Chuck , Chiu Hsien‐Tang 
Published: July 2012

AbstractCarbon nanotubes (CNTs) have been recognized as a potential superior reinforcement for high‐performance, multifunctional composites. However, non‐uniform CNT dispersion within the polymer matrix, the lack of adequate adhesion between the constituents of the composites, and lack of nanotube alignment have hindered significant improvements in composite performance. In this study, we present the development of a layer‐by‐layer assembly method to produce high mechanical performance and electrical conductivity CNT‐reinforced liquid crystalline polymer (LCP) composites using CNT sheets or buckypaper (BP) and self‐reinforcing polyphenylene resin, Parmax. The Parmax/BP composite morphology, X‐ray diffraction, mechanical, thermal, and electrical properties have been investigated. SEM observations and X‐ray diffraction demonstrate alignment of the CNTs due to flow‐induced orientational ordering of LCP chains. The tensile strength and Young's modulus of the Parmax/BP nanocomposites with 6.23 wt % multi‐walled carbon nanotube content were 390 MPa and 33 GPa, respectively, which were substantially improved when compared to the neat LCP. Noticeable improvements in the thermal stability and glass transition temperature with increasing CNT content due to the restriction in chain mobility imposed by the CNTs was demonstrated. Moreover, the electrical conductivity of the composites increased sharply to 100.23 S/cm (from approximately 10−13 S/cm) with the addition of CNT BP. These results suggest that the developed approach would be an effective method to fabricate high‐performance, multifunctional CNT/LCP nanocomposites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Preparation and characterization of electrospun Antheraea pernyi silk fibroin nanofibers from aqueous solution
Authors: He Jianxin , Cheng Yanmin , Cui Shizhong 
Published: July 2012

AbstractAntheraea pernyi silk fibroin nanofibers were prepared from aqueous solution with electrospinning. The viscosity and conductivity values of the A. pernyi silk fibroin aqueous solutions with different concentrations were measured, and the morphologies of the prepared electrospun nanofibers were observed by scanning electron microscopy. The morphologies of the electrospun nanofibers changed from beadlike to uniform cylindrical and then to beltlike. The A. pernyi silk fibroin aqueous solution with a concentration of 31% exhibited good spinnability, in which uniform and regular nanofibers with an average diameter of 422 nm were obtained. The secondary structure of the electrospun A. pernyi silk fibroin nanofibers was studied by solid 13C‐NMR cross‐polarization/magic angle spinning spectroscopy, X‐ray diffraction, and differential scanning calorimetry. The as‐spun A. pernyi silk fibroin nanofibers presented a complete α‐helix/random coil structure, and no β‐sheet structure was observed. After insoluble treatment with water vapor, α‐helix and β‐sheet conformations coexisted in the A. pernyi silk fibroin nanofibers, and the β‐sheet conformation was predominant. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Comparison of the nanoparticles performance in the photocatalytic degradation of a styrene–butadiene rubber nanocomposite
Authors: Arantes Tatiane M. , Sala Renata L. , Leite Edson R. , Longo Elson , Camargo Emerson R. 
Published: July 2012

AbstractMuch has been talking about the advantages of polymeric nanocomposites, but little is known about the influence of nanoparticles on the stability of these materials. In this sense, we studied the influence of both oxides of zirconium and titanium, known to have photocatalytic properties, as well as the influence of synthetic clay Laponite on the photodegradation of styrene–butadiene rubber (SBR). SBR nanocomposites were prepared by the colloidal route by mixing commercial polymer lattices and nanometric anatase TiO2, monoclinic ZrO2 or exfoliated Laponite clays colloidal suspensions. To better understand the degradation mechanisms that occur in these nanocomposites, the efficiency of different photocatalysts under ultraviolet radiation was monitored by FT‐IR and UV–vis spectroscopies and by differential scanning calorimetric. It was observed that TiO2 and ZrO2 nanoparticles undoubtedly acted as catalysts during the photodegradation process with different efficiencies and rates. However, when compared to pure SBR samples, the polymer degradation mechanism was unaffected. Unlike studies with nanocomposites montmorillonite, exfoliated laponite clay effectively acts as a photostabilizer of polymer UV photodegradation. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Synthesis and reactive features of a terpolymer: Poly(N‐vinyl‐2‐pyrrolidone‐co‐vinyl acetate‐co‐glycidyl methacrylate)
Authors: Hood David K. , Kranbuehl David E. , Glover A. Jaeton , Senak Laurence , Zhu Chao , Ozkan Seher , Musa Osama M. 
Published: July 2012

AbstractA polyvinyl pyrrolidone terpolymer system is described that can be chemically cross‐linked at moderate, 70–100°C, temperatures. The system has significant potential for development of durable long‐lasting pyrrolidone coatings in a wide range of applications, particularly in water filtration membrane construction where leaching is an unresolved, serious problem. The synthesis of the terpolymer, poly(N‐vinyl‐2‐pyrrolidone‐co‐vinyl acetate‐co‐glycidyl methacrylate), by free radical polymerization is described. The reactive features of this terpolymer are presented in the context of acidic anhydride curing. In a polar aprotic solvent, the terpolymer is reacted with poly(methyl vinyl ether‐co‐maleic acid) and cured thermally. Key aspects of the terpolymer synthesis and the acid anhydride cross‐linking reaction using DSC, rheology, FTIR, and a small molecule model system to study the cross‐linking chemistry are presented. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
AEBP1 gene variants in infants with gastroschisis
Authors: Feldkamp Marcia L. , Bowles Neil E. , Botto Lorenzo D. 
Published: July 2012

AbstractBACKGROUND: The AEBP1 (adipocyte enhancer binding protein) gene has two isoforms: AEBP1, the shorter of the two isoforms, and Aclp (aortic carboxypeptidase‐like protein). Aclp−/− mice demonstrate a ventral wall defect that is similar to gastroschisis in humans. Aclp is a potential candidate gene because it is expressed in numerous tissues during early development in mice; it associates with the extracellular matrix; and is essential for abdominal wall development and wound healing. In contrast, AEBP1 encodes an intracellular protein involved in proinflammatory responses, and may play a critical role in apoptosis and cell survival. Gastroschisis is a severe abdominal wall defect more common in young women and recently associated with a genitourinary infection early in pregnancy. METHODS: We screened AEBP1 in 40 cases of gastroschisis and compared identified variants in a control population. RESULTS: We identified several novel variants in AEBP1, including synonymous and nonsynonymous single nucleotide substitutions and intronic indels. However, the frequency of these variants was not significantly different from that of the control group, and the associated amino acid changes were predicted to be benign by two prediction software programs. CONCLUSIONS: Gastroschisis remains an intriguing defect that, for an unknown reason, occurs more commonly in young women and after a genitourinary infection. Although we found many alterations in AEBP1 among the gastroschisis cases, they were predicted to be benign. However, this gene requires further understanding of its interaction with other genes involved in the immune response pathway. Birth Defects Research (Part A) 94:738–742, 2012. © 2012 Wiley Periodicals, Inc.
Association of microtia with maternal nutrition
Authors: Ma Chen , Shaw Gary M. , Scheuerle Angela E. , Canfield Mark A. , Carmichael Suzan L. ,   National Birth Defects Prevention Study
Published: July 2012

AbstractBACKGROUNDFew studies have investigated the potential association of maternal dietary intake and risk of microtia among offspring.METHODSThe study included deliveries from 1997 to 2005 from the National Birth Defects Prevention Study. Nonsyndromic cases of microtia were compared to nonmalformed, population‐based, live‐born control infants by estimating adjusted odds ratios (ORs) and 95% confidence intervals (CIs) from logistic regression models that included maternal race or ethnicity, education, folic acid–containing supplement intake, fertility treatment, study site, and total energy intake.RESULTSComparing intake in the lowest 10th percentile versus the 10th to 90th percentiles, lower maternal intakes of carbohydrate (OR, 1.59; 95% CI, 1.07–2.38) and dietary folate (OR, 1.57; 95% CI, 1.09–2.25) were associated with elevated risk of microtia. In addition, results suggested that higher diet quality (as measured by the Diet Quality Index, and comparing the highest with the lowest quartile) was protective, but the CI did not exclude one (OR, 0.73; 95% CI, 0.50–1.07). Results were similar among obese and nonobese women.CONCLUSIONSThese data contribute to the limited body of evidence regarding the potential contribution of maternal nutrition to the etiology of microtia. Birth Defects Research (Part A) 2012. © 2012 Wiley Periodicals, Inc.
Self‐reported maternal smoking during pregnancy by source in Utah, 2003–2007
Authors: Srisukhumbowornchai Sivithee , Krikov Sergey , Feldkamp Marcia L. 
Published: July 2012

AbstractBACKGROUNDMaternal self‐report is the most common method for assessment of past cigarette exposure to assess birth defect risk. This study compared maternal smoking prior to and during pregnancy based on self‐reports obtained from the medical records abstracted for the Utah Birth Defect Network (UBDN), the birth certificate, and the computer‐assisted telephone interview (CATI) in the National Birth Defects Prevention Study (NBDPS). The study also investigated how the different sources for maternal smoking data affect estimates in an empirical study.METHODSA total of 1774 case and 618 control mothers who had participated in the NBDPS and whose live born infants were delivered between January 1, 2003, and December 31, 2007, were included in this study. Among the case mothers, we compared data from all three sources, whereas for control mothers only two data sources were available for comparison (i.e., birth certificate and CATI).RESULTSSmoking prevalence was highest in the CATI. Compared to the CATI, data from the UBDN had a higher sensitivity (61.3%) and better agreement (kappa = 0.63) than birth certificates (51.8%; kappa = 0.56). Adjusted odds ratios for all and specific birth defects (i.e., holoprosencephaly, hydrocephalus, anophthalmia/microphthalmia, anotia/microtia, total anomalous pulmonary venous return/partial anomalous pulmonary venous return [TAPVR/PAPVR], heterotaxy, and gastroschisis) were different between the birth certificate and CATI. The change in the effect estimates between the two sources ranged from 19% to 56%.CONCLUSIONSBased on our findings, maternal smoking exposure from interview data was shown to be of higher quality with less misclassification compared to data obtained from medical records or birth certificates. Birth Defects Research (Part A) 2012. © 2012 Wiley Periodicals, Inc.
Is adult stem cell aging driven by conflicting modes of chromatin remodeling?
Authors: Przybilla Jens , Galle Joerg , Rohlf Thimo 
Published: July 2012

AbstractEpigenetic control of gene expression by chromatin remodeling is critical for adult stem cell function. A decline in stem cell function is observed during aging, which is accompanied by changes in the chromatin structure that are currently unexplained. Here, we hypothesize that these epigenetic changes originate from the limited cellular capability to inherit epigenetic information. We suggest that spontaneous loss of histone modification, due to fluctuations over short time scales, gives rise to long‐term changes in DNA methylation and, accordingly, in gene expression. These changes are assumed to impair stem cell function and, thus, to contribute to aging. We discuss cell replication as a major source of fluctuations in histone modification patterns. Gene silencing by our proposed mechanism can be interpreted as a manifestation of the conflict between the stem cell plasticity required for tissue regeneration and the permanent silencing of potentially deleterious genomic sequences.
Deletion of galectin‐3 exacerbates microglial activation and accelerates disease progression and demise in a SOD1G93A mouse model of amyotrophic lateral sclerosis
Authors: Lerman Bruce J. , Hoffman Eric P. , Sutherland Margaret L. , Bouri Khaled , Hsu Daniel K. , Liu Fu‐Tong , Rothstein Jeffrey D. , Knoblach Susan M. 
Published: July 2012

AbstractGalectins are pleiotropic carbohydrate‐binding lectins involved in inflammation, growth/differentiation, and tissue remodeling. The functional role of galectins in amyotrophic lateral sclerosis (ALS) is unknown. Expression studies revealed increases in galectin‐1 mRNA and protein in spinal cords from SOD1
G93A mice, and in galectin‐3 and ‐9 mRNAs and proteins in spinal cords of both SOD1
G93A mice and sporadic ALS patients. As the increase in galectin‐3 appeared in early presymptomatic stages and increased progressively through to end stage of disease in the mouse, it was selected for additional study, where it was found to be mainly expressed by microglia. Galectin‐3 antagonists are not selective and do not readily cross the blood–brain barrier; therefore, we generated SOD1
G93A/Gal‐3
−/− transgenic mice to evaluate galectin‐3 deletion in a widely used mouse model of ALS. Disease progression, neurological symptoms, survival, and inflammation were assessed to determine the effect of galectin‐3 deletion on the SOD1
G93A disease phenotype. Galectin‐3 deletion did not change disease onset, but resulted in more rapid progression through functionally defined disease stages, more severely impaired neurological symptoms at all stages of disease, and expiration, on average, 25 days earlier than SOD1
G93A/Gal‐3
+/+ cohorts. In addition, microglial staining, as well as TNF‐α, and oxidative injury were increased in SOD1
G93A/Gal‐3
−/− mice compared with SOD1
G93A/Gal‐3
+/+ cohorts. These data support an important functional role for microglial galectin‐3 in neuroinflammation during chronic neurodegenerative disease. We suggest that elevations in galectin‐3 by microglia as disease progresses may represent a protective, anti‐inflammatory innate immune response to chronic motor neuron degeneration.
Significant Formation of Adipic Acid by Direct Oxidation of Cyclohexane Using Supported Nano‐Gold Catalysts
Authors: Alshammari Ahmad , Koeckritz Angela , Kalevaru Venkata Narayana , Bagabas Abdulaziz , Martin Andreas 
Published: July 2012

AbstractAdipic acid (AA) is one of the highest volume chemicals in world use with a wide range of commercial applications. This paper demonstrates the possibility of producing significant proportions of AA by the selective oxidation of cyclohexane (CH) in one step using various supported gold‐nanoparticle (AuNP) catalysts. The catalysts were characterized by ICP, BET, XRD, X‐ray photoelectron microscopy, and TEM. The catalytic activity tests were carried out in the liquid phase using autoclaves in the temperature range of 100–170 °C at 10 bar. A CH conversion of over 25 %, with 26% selectivity of AA and 70% selectivity of KA oil (cyclohexanone+cyclohexanol), was achieved over a nano‐gold/TiO2 (anatase) catalyst. The superior performance of this catalyst is attributed to the smaller size of AuNPs, which has an average particle size of 2 nm. Good correlation between activity and Au particle size could be achieved. Overall, the particle size of the AuNPs showed a strong influence on catalytic performance.
Current Statin Usage for Patients With Acute Coronary Syndrome Undergoing Percutaneous Coronary Intervention: Multicenter Survey in Korea
Authors: Kim Mi‐Jeong , Jeon Doo Soo , Gwon Hyeon‐Cheol , Kim Soo‐Joong , Chang Kiyuk , Kim Hyo‐Soo , Tahk Seung‐Jea ,   for Korean MUSTANG Investigators
Published: July 2012

AbstractBackground:Although high‐dose statin therapy has been reported to improve outcomes in patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI), patterns of statin usage for such patients have not been reported in real‐world clinical practice.Hypothesis:Some clinical factors would affect the pattern of statin usage in patients with ACS.Methods:In the multicenter prospective registry, 3362 patients with ACS who underwent PCI were analyzed. High‐dose statin treatment was defined as atorvastatin ≥40 mg or rosuvastatin ≥20 mg per day. The patterns of statin usage were investigated for 30 days after the index PCI.Results:High‐dose statins were administered prior to PCI to 13.7% and 19.6% of patients with unstable angina/non–ST‐elevated myocardial infarction (UA/NSTEMI) and ST‐elevated myocardial infarction (STEMI), respectively (P < 0.001). After PCI, 476 (14.2%) patients were maintained on high‐dose statins, and 550 (16.4%) patients received no statins. Independent factors associated with high‐dose statin usage after PCI were STEMI (odds ratio [OR]: 1.704, 95% confidence interval [CI]: 1.321–2.197, P < 0.001), high total cholesterol level (OR: 1.445, 95% CI: 1.136–1.837, P = 0.003), and current smoker (OR: 1.556, 95% CI: 1.206–2.008, P < 0.011). The absence of hypercholesterolemia was an independent factor determining the nonuse of statins (OR: 0.229, 95% CI: 0.148–0.353, P < 0.001).Conclusions:In real‐world clinical practice, high‐dose statin treatment is being underused despite extensive evidence for patients with ACS undergoing PCI, particularly in UA/NSTEMI. Efforts are needed to ensure that clinical practice complies with evidence‐based guidelines. Clin. Cardiol. 2012 doi: 10.1002/clc.22038This work was supported financially by Pfizer Pharmaceuticals Korea Ltd., which had no role in the study design, data collection, analysis, manuscript writing, or decision to proceed with publication. The authors have no other funding, financial relationships, or conflicts of interest to disclose.