bluuebunny/crossref_metadata_2025_split huggingface dataset:
Insights into poly(3‐hexylthiophene)‐b‐poly(ethylene oxide) block copolymer: Synthesis and solvent‐induced structure formation in thin films
Authors: Yang Hui , Xia Hao , Wang Guowei , Peng Juan , Qiu Feng 
Published: September 2012

AbstractWe report the synthesis, characterization, and solvent‐induced structure formation in thin films of an amphiphilic rod‐coil conjugated block copolymer, poly(3‐hexylthiophene)‐b‐poly(ethylene oxide). The diblock copolymers were prepared by a facile click reaction and their characterizations as well as thermal, crystalline, optical properties, and self‐assembly behavior have been investigated in detail. A series of morphologies including two‐phase separated nanostructure, nanofibrils, and their mixed morphology could be obtained depending on the selectivity of solvents to different blocks. Structural analyses demonstrate there is a subtle balance between microphase separation of copolymer and the π‐π stacking of the conjugated P3HT and such balance can be controlled by changing the solvents of different selectivity in solution and the length of P3HT block. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
The study of organic semiconductor/ferromagnet interfaces in organic spintronics: A short review of recent progress
Authors: Zhan Yiqiang , Fahlman Mats 
Published: September 2012

AbstractAn overview is given on recent results in organic spintronic research. In particular, so‐called spinterfaces, spin‐injecting interfaces involving organic semiconductor (OSC) molecules and ferromagnetic metals, are discussed. The interfaces are classified in different categories depending on the type and strength of interface interaction and the relevant physics concerning energy level alignment and spin polarization of interface states are explained. Examples are given on characterization of both interface energetics and spin‐related properties obtained from a wide variety of experimental techniques, highlighting the different ways contacting can modify the electronic and magnetic properties of the OSC molecules and the ferromagnetic metals at the resulting spinterfaces. Finally, models for spin injection at spinterfaces are presented and discussed, followed by some speculations on consequences for device design and performance. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012
Atomic mobility in strained glassy polymers: The role of fold catastrophes on the potential energy surface
Authors: Chung Yongchul G. , Lacks Daniel J. 
Published: September 2012

AbstractDeformation is known to enhance the atomic mobility in disordered systems such as polymer materials. To elucidate the origin of this phenomenon, we carry out two types of simulations: molecular dynamics (MD) simulations, which determine the atomic trajectories at finite temperature, and quasi‐static simulations, which determine the atomic trajectories in the limit of zero temperature (and in the limit of zero shear rate). The quasi‐static simulations show discontinuous changes in properties, such as system energy and atomic mobility. We use a normal mode analysis to show that these discontinuous changes arise from fold catastrophes of the potential energy landscape, in which energy minima flatten out and the heights of energy barriers decrease to zero; this was demonstrated by normal mode frequencies following a power law with an exponent of 0.5 as the discontinuous change is approached. After the fold catastrophe, the system relaxes to a different energy minimum, giving rise to atomic displacements. These fold catastrophes are the only mechanism for diffusive atomic displacements in the quasi‐static simulations, where there is no thermal energy. We compared the mean‐squared displacements as a function of strain from the quasi‐static simulations to those from MD simulations (which do include thermal effects)—the similarity of the values of the mean‐squared displacements in these two types of simulations demonstrates that the fold catastrophes underlie the enhanced dynamics in strained polymer systems even at finite temperature. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012
Synthesis, solid‐state, and charge‐transport properties of conjugated polythiophene‐S,S‐dioxides
Authors: Cochran Justin E. , Amir Elizabeth , Sivanandan Kulandaivelu , Ku Sung‐Yu , Seo Jung Hwa , Collins Brian A. , Tumbleston John R. , Toney Michael F. , Ade Harald , Hawker Craig J. , Chabinyc Michael L. 
Published: September 2012

AbstractAn alkylated semiconducting polymer comprising alternating bithiophene‐[all]‐S,S‐dioxide and aromatic monothiophene units in the polymer backbone was synthesized with the intent of modifying the energy gap and lowest unoccupied molecular orbital for use as a stable n‐type semiconductor. Films spun from this semiconducting polymer were characterized utilizing X‐ray scattering, near edge X‐ray absorption fine structure spectroscopy, ultraviolet photoelectron spectroscopy, and thin‐film field effect transistors to determine how oxidation of the thiophene ring systems impacts the structural and electronic properties of the polymer. The thiophene‐S,S‐dioxide polymers have lower optical and electrical band gaps than corresponding thiophene polymers. X‐ray scattering results indicate that the polymers are well ordered with the π–π stacking distances increased by 0.4 Å relative to analogous thiophene polymers. The electrical stability of these polymers is poor in transistors with a drop in the field effect mobility by approximately one order of magnitude upon addition of just 5% of the thiophene‐S,S‐dioxide unit in a copolymer with thiophene. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013
Kinetic Monte Carlo simulation of the epitaxial growth of Si(100)
Authors: Günther Vivien , Mauß Fabian , Klauer Christian , Schlawitschek Christiane 
Published: September 2012

Abstract3D Kinetic Monte Carlo (KMC) simulations have been carried out on the epitaxial growth of the silicon (100)2×1 surface as a function of surface temperature (570‐870 °C). The KMC model explicitly takes into account the anisotropy of the silicon (100)2×1 surface and the interaction of neighboring sites as a reaction event at a given surface site not only depends on the chemical nature of the site itself but also on steric factors and the local environment. Thus the model includes data about the local structure of the surface, the nature of the surface adatoms and their neighbors, the kinetic reaction parameters, and the incident precursor atoms. Reaction probabilities are calculated with the Arrhenius equation, kinetic parameters are taken from experimental and calculated data from the literature. First estimations are given for missing values. Silane is assumed to be the only gas‐phase reactant on the surface, coupling with the gas phase is carried out by silane partial pressure. For the first time a really complex algorithm comprehending 12 different surface sites and more than 100 reactions such as silane adsorption, SiHx decomposition and diffusion of adsorbed species is presented. The model provides a good fit to experimental observations and theoretical knowledge. Experimental data of growth rate and hydrogen coverage can be reproduced (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Joint pricing and openness decisions in software markets with reinforcing loops
Authors: Rahmandad Hazhir , Sibdari Soheil 
Published: September 2012

AbstractIn software markets, pricing and openness interact to determine profitability through the direct effect of openness on feasible prices and costs, and their impact on different reinforcing feedback loops such as network effects. We develop a simulation model of the inner workings of a software firm, product life cycle and market aggregation, and analyze their interactions in a competitive market. The reinforcing loops increase the value of early market lead and put pressure on the competing firms to seek such advantage. The competitive equilibrium under strong reinforcing loops calls for highly open software products with early discounts that significantly compromise the profitability of the players. Proprietary platforms and higher prices are favored when those mechanisms are weak. We discuss the implications of this analysis for the dynamics of different competitive markets as well as the contributions to the system dynamics literature in analyzing Nash equilibrium of differential games. Copyright © 2012 System Dynamics Society.
Progesterone‐enhanced sperm hyperactivation through IP3–PKC and PKA signals
Authors: Fujinoki Masakatsu 
Published: September 2012

AbstractProposeThe present study examined whether regulation of progesterone‐enhanced hyperactivation of spermatozoa is associated with the production of inositol 1,4,5‐trisphosphate (IP3) and diacylglycerol (DAG) by phospholipase C (PLC) and cyclic adenosine monophosphate (cAMP) by adenylate cyclase (AC), as well as activation of protein kinase C (PKC) and protein kinase A (PKA).MethodsHamster spermatozoa were hyperactivated by incubation for 4 h in modified Tyrode's albumin lactate pyruvate (mTALP) medium. In order to examine the effects of IP3 receptor (IP3R), PKC and PKA on progesterone‐enhanced hyperactivation, their inhibitors (xestospongin C, bisindolylmaleimide 1 and H‐89) were used.ResultsProgesterone‐enhanced hyperactivation was significantly suppressed by the inhibitors of IP3R, PKC and PKA.ConclusionsThe results suggest that progesterone‐enhanced sperm hyperactivation occurs through two signal pathways. One is an intracellular Ca2+ signal through production of IP3 and DAG by PLC, binding of IP3 to IP3R and activation of PKC by DAG and Ca2+. The other is a cAMP–PKA signal through production of cAMP by AC and activation of PKA by cAMP.
Prepubertal exposure to glucocorticoid delays puberty independent of the hypothalamic Kiss1‐GnRH system in female rats
Authors: Kinouchi Riyo , Matsuzaki Toshiya , Iwasa Takeshi , Gereltsetseg Ganbat , Nakazawa Hiroshi , Kunimi Kotaro , Kuwahara Akira , Yasui Toshiyuki , Irahara Minoru 
Published: September 2012

AbstractSecretion of glucocorticoids is widely known as a key endocrine response to stresses. Prenatal dexamethasone administration induces intrauterine growth retardation and delayed onset of puberty in female rats independent of the hypothalamic Kiss1‐gonadotropin‐releasing hormone (GnRH) system. The aim of this study was to evaluate the influence of chronic intracerebroventricular (central, CD) or subcutaneous (peripheral, PD) dexamethasone administration to prepubertal female rats on the onset of puberty and body weight change. Rats administered dexamethasone from day 25 to day 34 (CD and PD) showed significantly reduced body weight gain throughout the experimental period and delayed onset of vaginal opening compared with rats administered saline centrally (CS) or peripherally (PS). At 34 days old, hypothalamic Kiss1r mRNA levels were significantly lower with CD than with CS. No significant differences were seen between rats administered saline and rats administered dexamethasone with regard to hypothalamic Kiss1, GnRH and NPY mRNA levels or serum LH levels. Serum leptin concentrations were higher in CD and PD than in the controls (CS and PS). These results suggest that the delayed onset of puberty induced by prepubertal dexamethasone administration occurs independent of the hypothalamic Kiss1‐GnRH system.
On non-self-similar regimes in homogeneous isotropic turbulence decay
Authors: Meldi Marcello , Sagaut Pierre 
Published: September 2012

AbstractBoth theoretical analysis and eddy-damped quasi-normal Markovian (EDQNM) simulations are carried out to investigate the different decay regimes of an initially non-self-similar isotropic turbulence. Breakdown of self-similarity is due to the consideration of a composite three-range energy spectrum, with two different slopes at scales larger than the integral length scale. It is shown that, depending on the initial conditions, the solution can bifurcate towards a true self-similar decay regime, or sustain a non-self-similar state over an arbitrarily long time. It is observed that these non-self-similar regimes cannot be detected, restricting the observation to time exponents of global quantities such as kinetic energy or dissipation. The actual reason is that the decay is controlled by large scales close to the energy spectrum peak. This theoretical prediction is assessed by a detailed analysis of triadic energy transfers, which show that the largest scales have a negligible impact on the total transfers. Therefore, it is concluded that details of the energy spectrum near the peak, which may be related to the turbulence production mechanisms, are important. Since these mechanisms are certainly not universal, this may at least partially explain the significant discrepancies that exist between experimental data and theoretical predictions. Another conclusion is that classical self-similarity theories, which connect the asymptotic behaviour of either the energy spectrum $E(k\ensuremath{\rightarrow} 0)$ or the velocity correlation function $f(r\ensuremath{\rightarrow} + \infty )$ and the turbulence decay exponent, are not particularly relevant when the large-scale spectrum shape exhibits more than one range.
The effect of dry cow antibiotic with and without an internal teat sealant on udder health during the first 100 d of lactation: a field study with matched pairs
Authors: Mütze Katja , Wolter Wilfried , Failing Klaus , Kloppert Bärbel , Bernhardt Heinz , Zschöck Michael 
Published: September 2012

The objective of this field study was to compare the udder health status as well as the clinical mastitis rate during the first 100 d of lactation in cows that received long-acting dry cow antibiotic alone (group AB) or in combination with an internal teat sealant (group AB + OS). The study was conducted during a 9-month period and included 136 Holstein cows from 12 dairy farms in Hessia, Germany. Between days 1 and 5 after calving a California mastitis test (CMT) was performed. Milk-samples were collected for bacteriological culture before drying off, between days 6 and 14 and days 35 and 56 of lactation. Additionally the cows were monitored for the occurrence of clinical mastitis events until 100 d post partum. Within the 12 herds cow-pairs were formed on the basis of age, milk yield and SCC. A cow-pair consisted of one cow from group AB and one cow from group AB + OS. For statistical analysis within every cow-pair one quarter that has been dried off with internal teat sealant and dry cow antibiotic (group AB + OS) was compared with one quarter that has been dried off with dry cow antibiotic (group AB) alone. As criterion for the matching process of udder quarters the cytobacteriological udder health status before drying off was used. A total of 544 quarters (136 cows) were used in this analysis. In the first 5 d after calving, group AB had significantly more quarters with a positive CMT reaction than group AB + OS (85vs. 57;P <0·001), and in the first 100 d of lactation, group AB had more quarters with clinical mastitis than group AB + OS (25vs. 15;P = 0·03). In the time periods 6–14 and 35–56 d of lactation, there were fewer quarters in group AB + OS populated withCorynebacteriumspp. (days 6–14,P = 0·05; days 35–56,P = 0·02) and aesculin-positive streptococci (days 35–56,P = 0·02). The internal teat sealant was a promising tool for the prevention of new intramammary infections (IMI) of dry cows with environmental udder pathogens as expressed during early lactation.
Herd-level determinants of bovine leukaemia virus prevalence in dairy farms
Authors: Erskine Ronald J , Bartlett Paul C , Byrem Todd M , Render Chelsea L , Febvay Catherine , Houseman Jessica T 
Published: September 2012

The prevalence of bovine leukaemia virus (BLV) was determined in 113 Michigan dairy herds by ELISA testing for anti-BLV antibodies in milk. Additionally, an interview regarding management practices with cooperating herd managers identified farm-level variables thought to be associated with prevalence of BLV. Twenty-three risk factors (P ⩽ 0·1) were identified on one-way ANOVA or simple linear regression. Multivariate analysis identified several management practices whose predictive value for increased prevalence of BLV may relate to transmission among herd mates, e.g. reuse of hypodermic needles, lack of fly control, gouge dehorning and increased use of injections in dry cows. Additionally, exclusive breeding of heifers with artificial insemination was associated with decreased BLV prevalence, as compared with at least some use of natural service by a bull. Although intervention studies are needed before causal relationships can be concluded, and unaccounted variables related to transmission exist among dairy herds, these findings suggest management practices that may help dairy producers reduce the transmission of BLV within their herds.
Delayed carotid blow-out syndrome: a new complication of chemoradiotherapy treatment in pharyngolaryngeal carcinoma
Authors: Esteller E , León X , de Juan M , Quer M 
Published: September 2012

AbstractBackground:Carotid blow-out syndrome is one of the most devastating complications of head and neck carcinoma. It usually occurs as a post-operative complication or when the tumour compromises the vascular axis.Methods and results:We report two patients who suffered carotid blow-out syndrome but who did not have the usual predisposing factors. Both patients had a pharyngolaryngeal carcinoma that was treated with chemoradiotherapy. Residual non-tumoural ulceration was seen along the lateral wall of the hypopharynx in both cases. This ulceration eventually reached the vascular axis, precipitating carotid rupture and death.Conclusion:Residual non-tumoural ulceration of the lateral wall of the hypopharynx after chemoradiotherapy should be considered with the utmost caution. Once persistence of the tumour is excluded, surgery is indicated to protect the vascular axis, in order to prevent carotid blow-out syndrome.
Guillotine versus dissection tonsillectomy: randomised, controlled trial
Authors: Frampton S J , Ward M J A , Sunkaraneni V S , Ismail-Koch H , Sheppard Z A , Salib R J , Jain P K 
Published: September 2012

AbstractObjective:This trial aimed to compare the guillotine technique of tonsillectomy with ‘cold steel’ dissection, the current ‘gold standard’.Design:A single centre, randomised, controlled trial.Methods:One hundred children aged 3 to 11 years who were listed for bilateral tonsillectomy were recruited. Patients had one tonsil removed by each technique, and were blinded to the side. The operative time, intra-operative blood loss, haemostasis requirement and post-operative pain scores were recorded and compared.Results:Operative time and intra-operative blood loss were both significantly less for the guillotine technique (p < 0.001) and there was a significantly reduced haemostasis requirement (p < 0.001). Pain was also less on the guillotine side (p < 0.001). There were no tonsillar remnants or palatal trauma for either technique. There was no significant difference between techniques in the frequency of secondary haemorrhage.Conclusion:This study provides level Ib evidence that guillotine tonsillectomy in children with mobile tonsils is an effective and time-efficient procedure which produces less intra-operative blood loss and post-operative pain than cold steel dissection.
Involvement of focal adhesion kinase in cellular proliferation, apoptosis and prognosis of laryngeal squamous cell carcinoma
Authors: Li D W , Sun Y J , Sun Z F , Dong P 
Published: September 2012

AbstractObjective:This study aimed to investigate the relationship between focal adhesion kinase expression and clinicopathological factors, cell apoptosis and proliferation, and overall survival, in laryngeal squamous cell carcinoma.Methods:Immunohistochemical staining was used to detect the expression of focal adhesion kinase and proliferating cell nuclear antigen in tissue samples. Apoptotic cells were assessed using the terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate nick end labelling (‘TUNEL’) method.Results:The proportion of focal adhesion kinase expression was 73.26 per cent in tumour tissues, significantly greater than in normal tissues (p < 0.05), and was significantly related to laryngeal cancer clinical stage, lymph node metastasis and overall survival (p < 0.05). In the tumour cases assessed, up-regulation of focal adhesion kinase expression was significantly associated with decreased cell apoptosis and increased proliferation (p < 0.05).Conclusion:These findings suggest that focal adhesion kinase may affect laryngeal squamous cell carcinoma progression through regulation of cell apoptosis and proliferation. Focal adhesion kinase expression is a major prognostic factor in laryngeal cancer patients.
Transtympanic balloon dilatation of eustachian tube: a human cadaver pilot study
Authors: Kepchar J , Acevedo J , Schroeder J , Littlefield P 
Published: September 2012

AbstractObjective:To determine the feasibility and safety of transtympanic balloon dilatation of the eustachian tube.Methods:Transtympanic eustachian tube dilatation was performed on six cadaver heads using balloon catheters. Catheters were placed in each eustachian tube and the head scanned by computed tomography. Randomised, blinded dilatation of one balloon in each head was performed, followed again by a second computed tomography scan. The scans were reviewed by a neurotologist and neuroradiologist who were blinded to previous treatment, and measurable dilatation and incidental damage noted.Results:There was adequate placement of the balloon catheter beyond the bony isthmus in 6 of 10 eustachian tubes. There was one insufficient catheter placement and three adverse placements (one into the petrous carotid canal and two into the vidian canal). Only one dilated tube showed a measurable increase in diameter.Conclusion:This experiment revealed serious safety issues with transtympanic eustachian tube dilatation. Therefore, this approach should not be considered feasible at this time.
Prognostic value of cathepsin L and its inhibitor headpin in oral squamous cell carcinoma
Authors: Nakashima T , Yasumatsu R , Masuda M , Clayman G L , Komune S 
Published: September 2012

AbstractObjective:To investigate the clinicopathological and prognostic significance of the expression of cathepsin L and its inhibitor headpin, in oral squamous cell carcinoma.Design:Immunohistochemical studies were performed on 56 oral squamous cell carcinoma samples. We evaluated the relationship between cathepsin L and headpin expression versus patients' clinicopathological factors and survival.Results:The group that was positive for cathepsin L expression tended to have positive metastatic neck lymph nodes and a poorer prognosis. Headpin expression was not related to metastasis or prognosis. Well differentiated squamous cell carcinoma had higher levels of headpin expression compared with poorly differentiated squamous cell carcinoma.Conclusion:Cathepsin L expression is related to the invasive and metastatic potential of oral squamous cell carcinoma.