bluuebunny/crossref_metadata_2025_split huggingface dataset:
Star and Hyperbranched Polyisobutylenes via Terminally Reactive Polyisobutylene‐Polystyrene Block Copolymers
Authors: Kali Gergely , Szesztay Márta , Bodor Andrea , Iván Béla 
Published: January 2013

AbstractUnique, highly branched polyisobutylenes (PIB) were prepared via quasiliving carbocationic copolymerization of isobutylene and styrene (St) monomers. The junction points were formed by Friedel‐Crafts self alkylation of PSt segments by the carbocationic chain ends. First, linear PIB was prepared with reactive chain ends. This was reacted with St monomer to form PIB‐b‐PSt AB, and PSt‐b‐PIB‐b‐PSt ABA type triblock copolymers with reactive carbocationic chain ends. The terminal carbonations react with the phenyl group of the polystyrene end‐segments of the block copolymers leading to chain coupling, and thus PIB star polymers in the case of AB and hyperbranched PIB from ABA block copolymers. The resulting branched polymers were characterized and the branch formation was confirmed by gel permeation chromatography (GPC) and proton nuclear magnetic resonance spectroscopy (1H NMR).
Caffeine consumption and risk of dyskinesia in CALM‐PD
Authors: Wills Anne‐Marie A. , Eberly Shirley , Tennis Marsha , Lang Anthony E. , Messing Susan , Togasaki Daniel , Tanner Caroline M. , Kamp Cornelia , Chen Jiang‐Fan , Oakes David , McDermott Michael P. , Schwarzschild Michael A. ,   on behalf of the Parkinson Study Group
Published: January 2013

ABSTRACTBackgroundAdenosine A2A receptor antagonists reduce or prevent the development of dyskinesia in animal models of levodopa‐induced dyskinesia.MethodsWe examined the association between self‐reported intake of the A2A receptor antagonist caffeine and time to dyskinesia in the Comparison of the Agonist Pramipexole with Levodopa on Motor Complications of Parkinson's Disease (CALM‐PD) and CALM Cohort extension studies, using a Cox proportional hazards model adjusting for age, baseline Parkinson's severity, site, and initial treatment with pramipexole or levodopa.ResultsFor subjects who consumed >12 ounces of coffee/day, the adjusted hazard ratio for the development of dyskinesia was 0.61 (95% CI, 0.37–1.01) compared with subjects who consumed <4 ounces/day. For subjects who consumed between 4 and 12 ounces/day, the adjusted hazard ratio was 0.73 (95% CI, 0.46–1.15; test for trend, P = .05).ConclusionsThese results support the possibility that caffeine may reduce the likelihood of developing dyskinesia. © 2013 Movement Disorder Society
Neuropeptides trigger oocyte maturation and subsequent spawning in the hydrozoan jellyfish Cytaeis uchidae
Authors: Takeda Noriyo , Nakajima Yoko , Koizumi Osamu , Fujisawa Toshitaka , Takahashi Toshio , Matsumoto Midori , Deguchi Ryusaku 
Published: January 2013

AbstractOocyte maturation and subsequent spawning in hydrozoan jellyfish are generally triggered by light‐dark cycles. To examine if the initiation of the maturation process after light stimulus is mediated by neurotransmitters, neuropeptides isolated originally from Hydra magnipapillata were applied to sexually mature female medusae of the hydrozoan jellyfish Cytaeis uchidae. Among the Hydra neuropeptides tested, Hym‐53 (NPYPGLW‐NH2), as well as a nonphysiological peptide, CGLWamide (CGLW‐NH2), were most effective in inducing oocyte maturation and spawning. Hym‐355 (FPQSFLPRG‐NH2) also triggered these events, but the stimulatory effect was weaker. Since Hym‐53‐OH (NPYPGLW) and Hym‐355‐OH (FPQSFLPRG) had no effect, amidation at the C‐terminus may be critical for the stimulatory activities of the peptides. Exposure to Hym‐53 for 2 min was sufficient to trigger of oocyte maturation, and the spawned eggs were able to be fertilized and to develop normally. Transmission electron microscopy confirmed that bundles of axon‐like structures that contain dense‐core synaptic vesicles and microtubules are present in the ovarian ectodermal epithelium overlying the oocytes. In addition, immunohistological analyses revealed that some of the neurons in the ectodermal epithelium are GLWamide‐ and PRGamide‐positive. These results suggest that a neuropeptide signal transduction pathway is involved in mediating the induction of oocyte maturation and spawning in this jellyfish. Mol. Reprod. Dev. 80: 223–232, 2013. © 2013 Wiley Periodicals, Inc.
Study of Plastic Explosives based on Attractive Cyclic Nitramines, Part II. Detonation Characteristics of Explosives with Polyfluorinated Binders
Authors: Elbeih Ahmed , Pachman Jiri , Zeman Svatopluk , Trzcinski Waldemar A. , Suceska Muhamed 
Published: January 2013

AbstractA series of plastic bonded explosives (PBXs) based on Viton A and Fluorel binders were prepared using four nitramines, namely RDX (1,3,5‐trinitro‐1,3,5‐triazinane), β‐HMX (β‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocane), BCHMX (cis‐1,3,4,6‐tetranitro‐octahydroimidazo‐[4,5‐d]imidazole), and ε‐HNIW (ε‐2,4,6,8,10,12‐hexanitro‐2,4,6,8,10,12‐hexaazaisowurtzitane). The detonation velocities, D, were determined. Detonation parameters were also calculated by means of modified Kamlet & Jacobs method, CHEETAH and EXPLO5 codes. In accordance with our expectations BCHMX based PBXs performed better than RDX based ones. The Urizar coefficient for Fuorel binder was also calculated.
Modeling of Ignition in a Single Layer of Impacted Energetic Crystals
Authors: Wu Yan‐Quing , Huang Feng‐Lei , Huang Ming 
Published: January 2013

AbstractA thermal‐mechanical model for the ignition of a layer of cyclotetramethylene tetranitramine (HMX) particles under drop‐weight impact was developed. Considering the micro‐particle plasticity, frictional heating, melting, fracture, and chemical reaction at particle level, effects of loading parameters and sample characteristics on ignition and mechanical responses were discussed. The threshold values for ignition to occur under different loading conditions and various material parameters can be predicted. The model was validated by comparing experimental measured and calculated mean pressure‐strain curves, which showed two turning points due to localized fragmentation and melting. Relationships between thermal and mechanical responses at the particle level were examined.
Factors Influencing Triacetone Triperoxide (TATP) and Diacetone Diperoxide (DADP) Formation: Part I
Authors: Oxley Jimmie C. , Smith James L. , Bowden Patrick R. , Rettinger Ryan C. 
Published: January 2013

AbstractConditions, which result in the formation of triacetone triperoxide (TATP) or diacetone diperoxide (DADP) from acetone and hydrogen peroxide (HP, were studied for the purposes of inhibiting the reaction. Reaction of HP with acetone precipitates either DADP or TATP, but the overall yield and amount of each was found to depend on (1) reaction temperature, (2) the molar ratio of acid to HP/acetone, (3) initial concentrations of reactants, and (4) length of reaction. Controlling molar ratios and concentrations of starting materials was complicated because both sulfuric acid and hydrogen peroxide were aqueous solutions. Temperature exercised great control over the reaction outcome. Holding all molar concentrations constant and raising the temperature from 5 to 25 °C showed an increase of DADP over TATP formation and a decrease in overall yield. At 25 °C a good yield of TATP was obtained if the HP to acetone ratio was kept between 0.5 : 1 and 2 : 1. At constant temperature and HP‐to‐acetone held at one‐to‐one ratio, acid‐to‐HP molar ratios between 0.10 : 1 and 1.2 : 1 produced good yield of TATP. Plotting the molality of HP vs. that of sulfuric acid revealed regions, in which relatively pure DADP or pure TATP could be obtained. In addition to varying reaction conditions, adulterants placed into acetone were tested to inhibit the formation of TATP. Because there is much speculation of the relative stability, sensitivity, including solvent wetting of crystals, and performance of DADP and TATP, standard tests (i.e. DSC, drop weight impact, and SSED) were performed.
Solvent Free Microwave Assisted Isomerization of N‐Nitropyrazoles
Authors: Ravi Pasupala , Tewari Surya P. 
Published: January 2013

AbstractThis paper describes solvent‐free isomerization of N‐nitropyrazoles under microwave irradiation to achieve a new green chemistry procedure for the synthesis of C‐ nitropyrazoles in good to excellent yields. The presented procedure requires less time, offers simplified workup procedure, needs no obnoxious solvents, and may be used for the preparation of several C‐nitropyrazoles.
The effect of Ga‐doping on the defect chemistry of RE3Al5O12 garnets
Authors: Stanek C. R. , Jiang C. , Yadav S. K. , McClellan K. J. , Uberuaga B. P. , Andersson D. A. , Nikl M. 
Published: January 2013

AbstractIt has been recently shown that the addition of Ga to Lu3Al5O12 garnet (LuAG) removes the electron trapping associated with cation antisite defects. In this paper, we show via atomic scale simulations that the replacement of Al with Ga in LuAG actually lowers the energy of the antisite disorder process. Thus, we predict that Ga additions will lead to an increase of the antisite defect concentration and, in the absence of the electronic structure changes, would actually degrade the performance of the material. Since there are two crystallographically distinct Al sites in the garnet structure, we not only present results for complete replacement of Al with Ga, but also partial replacement for 40% (on 16a) and 60% (on 24d) of the Al with Ga. Our results support the explanation for Ga‐doping leading to improvement in garnet scintillator performance that relies on variations of the electronic structure rather than reduction of the antisite defect concentration. magnified imageCation antisite defects in RE3Al5O12 garnet, where small light gray atoms and large dark gray atoms are lattice Al and RE atoms, respectively. The constituents of the antisite defect pairs are labeled, and it should be noted that the Ga atom (blue) is similar in size to RE (green). Oxygen atoms are not shown for clarity.
Influence of Ir and La substitution on the thermal transport properties of YbRh2Si2
Authors: Stockert Ulrike , Pfau Heike , Hartmann Stefanie , Lausberg Stefan , Friedemann Sven , Krellner Cornelius , Wirth Steffen , Geibel Christoph , Steglich Frank 
Published: January 2013

AbstractWe investigate the influence of small amounts of Ir and La substitution on the low‐temperature thermal conductivity κ and thermopower S of YbRh2Si2. While the thermal conductivity is reduced in both cases due to the introduction of additional impurities, the effect on the thermopower is non‐uniform: Ir substitution leads to a reduction of the absolute value of the thermopower. This is attributed largely to an enhanced disorder scattering. On the other hand, La substitution increases the absolute thermopower values. We discuss the possibility that this is due to band structure modifications upon doping into the Yb sublattice.
Photonic band gap active waveguide filters based on dilute nitrides
Authors: Calò Giovanna , Grande Marco , Alexandropoulos Dimitris , Petruzzelli Vincenzo 
Published: January 2013

AbstractThe wavelength filtering characteristics of active defective Photonic Band Gap (PBG) waveguides based on dilute nitrides are examined. The analyzed structure is made of GaInNAs‐GaInAs MQW ridge waveguides in which a geometrical active defect in the periodic lattice induces selective transmission spectral regions centered at different wavelengths inside the PBG. The device show the advantage of simultaneous DWDM selective filtering and amplification of the filtered signal. The performances of the active PBG filters are investigated as a function of the geometrical and the electrical parameters. The analysis is performed by using proprietary codes, based on the Bidirectional Beam Propagation Method with the Method of Lines introducing the rate equations. Highly selective 9‐channel active filter with minimum value of the bandwidth at half‐height transmittance B3dB=0.12 nm has been calculated. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Point defects in calcite used to estimate the date of arrival of first settlers in central region of Brazil
Authors: Cano Nilo F. , Etchvarne Carlos A. , Munita Casimiro S. , Rocca Rene R. , Barbosa Renata F. , Watanabe Shigueo 
Published: January 2013

AbstractA calcite formation was found on a rock‐wall painting at Chapada de Diamantina in a site in between Serra da Capivara National Park and Montalvania, Piaui, Brazil. Thermoluminescence and electron paramagnetic resonance (EPR) dating of this calcite gave an age of 40 to 55 ka, indicating that humans lived there prior to 40 ka ago. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
HVPE growth of GaN in the semipolar direction on planar Si(210)
Authors: Bessolov Vasily , Konenkova Elena , Shcheglov Mikhail , Sharofidinov Shukrillo , Kukushkin Sergey , Osipov Andrey , Nikolaev Vladimir 
Published: January 2013

AbstractA layer of semipolar gallium nitride was grown on Si(210) substrate by hydride vapor phase epitaxy (HVPE). As a buffer a nanocrystalline layer of 3C‐SiC was used. It has been found that anisotropic strain of the growing nitride layer changed the crystallographic orientation of its surface: with increasing layer thickness orientation of the surface changed sequentially as follows: (0001), (10‐15), (10‐14), (10‐13) and, finally, (10‐12). (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mechanisms behind efficiency droop and degradation in InGaN/GaN LEDs
Authors: Shmidt Natalia , Greshnov Andrew , Chernyakov Anton , Levinshtein Michael , Zakgeim Alexander , Shabunina Evgeniia 
Published: January 2013

AbstractThe results of low frequency noise studies in power blue InGaN/GaN LEDs with external quantum efficiency 30‐45% classified by leakage current (LC) values before and after degradation are reported. The LC values at V< 2V integrally characterize electrical properties of extended defect system (EDS) that is typical for InGaN/GaN LEDs. The smaller concentration of extended defects and length of dilatation, dislocation boundaries, the lower LC value is. It has been demonstrated that non‐radiative recombination processes (NRRP) localized in extended defect system (EDS) contribute in efficiency droop of LEDs at j ≥ 10 A/cm2. The main characteristics of degradation processes such as: (1) increase in tunneling current values related with EDS, at U ≤ 2 V, (2) strong deterioration of p‐n junction rectification properties, (3) formation of conductive paths along EDS; (4) increase in non‐uniformity of current distribution, and (5) the formation of local overheating channels at j > 10 A/cm2 along EDS had been revealed. The NRRP are localized along EDS and can be considered as a general mechanism of efficiency droop and the ambiguous degradation process in power InGaN/GaN LEDs (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nondestructive method for evaluation of electrical parameters of AlGaN/GaN HEMT heterostructures
Authors: Paszkiewicz Bogdan , Wosko Mateusz , Paszkiewicz Regina , Tlaczala Marek 
Published: January 2013

AbstractImpedance spectroscopy methods were proposed for direct evaluation of electrical properties of the AlGaN/GaN heterostructures. The impedance spectra were measured using a two contact mercury probe. Application of the proper distributed elements equivalent circuits enabled to evaluate not only the typically obtained parameters of the heterostructures such as sheet carriers concentration and its pinch off voltage but also the dependence of the channel sheet resistance and the mobility of 2DEG on d.c. gate bias (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Hot Strength and Creep Resistance of a High Interstitial Austenitic CrMn Steel
Authors: Berns Hans , Geenen Karina 
Published: January 2013

AbstractThe hot strength and short‐time creep resistance of austenitic steel CN0.85 with about (mass%) 18Cr, 18Mn, 0.6N, and 0.25C was investigated up to 700°C together with the corresponding structural changes of the solution annealed or cold worked initial states. In the primary creep range, the creep rate was rapidly reduced to the minimum creep rate and the more so after initial cold working. This also lowered the minimum creep rate but hardly the time to fracture. Precipitation of carbides and nitrides occurred in or near grain boundaries which gave rise to creep cracks. Precipitates within the grains, visible only in the overaged state, are assumed to have raised the resistance to creep. Comparing the creep strength of CN0.85 with standard hot work tool steel H11 points to an advantage of the former at service temperatures of >550°C. However, tests in practice are required to back up the favorable results of this tentative study.
Modeling the Viscosity of Alumino‐Silicate Melt
Authors: Zhang Guo‐Hua , Chou Kuo‐Chih 
Published: January 2013

AbstractThe structurally based viscosity model for aluminosilicate melts is developed, in which the influence of melt structure on viscosity is expressed by the definitions of different types of oxygen ions: (i) bridging oxygen OSi, bonded to Si4+ ions (ii) non‐bridging oxygen ${\rm O}_{{\rm Si}}^{i} $, bonded to Si4+ ion and cation i from basic oxide, (iii) free oxygen Oi, bonded to i ions, (iv) bridging oxygen OAi,i, bonded to an Al3+ ion charge compensated by cation i; (v) non‐bridging oxygen ${\rm O}_{{\rm Al, }i}^{j} $, bonded to the metal cation j and Al3+ ion charge compensated by cation i; (vi) oxygen OAl, bonded to an Al3+ ion which is not charge compensated. A systematic method is proposed to calculate numbers of these oxygen ions. According to the calculation results of the viscosity model, it has been found that the abilities of basic oxides to decrease viscosity follow the order: FeO > MnO > CaO > MgO, when Al2O3 is absent. The viscosities of quinary, quarternary, ternary, binary, and unary systems involving MgO, CaO, FeO, MnO, Al2O3, and SiO2 components are calculated by the present model, with all the mean deviations not >30%. Furthermore, it is indicates a better precision of the present model than that of other models for the same systems.
Differentiation-Related Response to DNA Breaks in Human Mesenchymal Stem Cells
Authors: Oliver Lisa , Hue Erika , Séry Quentin , Lafargue Audrey , Pecqueur Claire , Paris François , Vallette François M. 
Published: January 2013

Abstract
We have recently shown that the in vitro differentiation of human mesenchymal stem cells (hMSCs) was accompanied by an increased sensitivity toward apoptosis; however, the mechanism responsible for this shift is not known. Here, we show that the repair of DNA double-strand breaks (DSBs) was more rapid in undifferentiated hMSCs than in differentiated osteoblasts by quantification of the disappearance of γ-H2AX foci in the nuclei after γ-irradiation-induced DNA damage. In addition, there was a marked and prolonged increase in the level of nuclear Ku70 and an increased phosphorylation of DNA-PKcs. This was accompanied by an augmentation in the phosphorylation of ATM in hMSCs post-irradiation suggesting the nonhomologous end joining repair mechanism. However, when hMSCs were induced to differentiate along the osteogenic or adipogenic pathways; irradiation of these cells caused an expeditious and robust cell death, which was primarily apoptotic. This was in sharp contrast to undifferentiated hMSCs, which were highly resistant to irradiation and/or temozolomide-induced DSBs. In addition, we observed a 95% recovery from DSB in these cells. Our results suggest that apoptosis and DNA repair are major safeguard mechanisms in the control of hMSCs differentiation after DNA damage.
Mosquito Net Mesh for Abdominal Wall Hernioplasty: A Comparison of Material Characteristics with Commercial Prosthetics
Authors: Sanders David L. , Kingsnorth Andrew N. , Stephenson Brian M. 
Published: January 2013

AbstractBackgroundThe use of sterilized mosquito net as a cheaper alternative to commercial mesh used in hernia repair has previously been published. However, as no standards with regard to the material have been documented, we aimed to define the characteristics of a commonly available and low‐cost mosquito net, which has already been shown to be clinically efficacious in groin hernia repair. We compared its characteristics to other commercially available meshes, in keeping with the well‐established FDA and MHRA regulatory processes.MethodsThe macromolecular structure of the mosquito net was determined by vibrational spectroscopy. The ultrastructure of the meshes was examined with scanning electron microscopy, and uniaxial and burst tensile strength testing was performed. The following parameters were assessed: polymer type, filament characteristics, pore size, weight, linear density, elasticity, and tensile strength.ResultsThe mosquito net was a polyethylene homopolymer, knitted from monofilament fibers with a mean filament diameter of 109.7 μm and a mean mesh thickness of 480 μm. The mean pore maximum diameter was 1.9 mm, with 91.2 % porosity, 53.7 g/m2 mean mesh weight, and a linear mass density of 152 denier. This was comparable to the “large pore” (class I) commercial meshes. The bursting force for polyethylene mosquito net was greater than for UltraPro and Vypro (43.0 vs. 35.5 and 27.2 N/cm, respectively), and the mosquito net exhibited less anisotropy compared to the commercial meshes.ConclusionsThe material and mechanical properties of the polyethylene mosquito net are substantially equivalent to those of commonly used lightweight commercial meshes.
Identifying and Addressing Preventable Process Errors in Trauma Care
Authors: Pucher Philip H. , Aggarwal Rajesh , Twaij Ahmed , Batrick Nicola , Jenkins Michael , Darzi Ara 
Published: January 2013

AbstractBackgroundManagement of the acute trauma patient is complex, with potential for error and adverse events. Avoidable injuries and deaths are not well understood. Analysis of error incidence, type, and severity can aid in greater understanding of the root causes and guide future development of error reduction strategies.MethodsWeekly case review meetings for a UK trauma center were retrospectively reviewed over 1 year. Errors were identified and corroborated with case‐note review by a reviewer blinded to any identified events. All events were classified according to the Joint Commission on Accreditation of Healthcare Organisations taxonomy and were typified as structural or process errors and omission or commission errors.ResultsA total of 1,752 major trauma patients were admitted over the study period, and 169 preventable errors were identified through analysis of case review meetings and case‐note review. Clear patient harm was identified in 3.6 % of cases, with risk of harm in 30 %. Most errors occurred during the initial phase of care in the emergency department (51 %) and resulted most commonly in delays (56 %). The majority of errors were identified as process‐related (88 %), with 62 % of them considered errors of omission.ConclusionsThis study reports error incidence in trauma and typifies them according to type and root cause. It identifies process errors and errors of omission in particular as the most common recurring events. Error theory suggests that protocols or checklists may most effectively address these errors. Further study should be prospective and may aid in the development of such interventions.