bluuebunny/crossref_metadata_2025 huggingface dataset:
The collagen I mimetic peptide DGEA enhances an osteogenic phenotype in mesenchymal stem cells when presented from cell‐encapsulating hydrogels
Authors: Mehta Manav , Madl Christopher M. , Lee Shimwoo , Duda Georg N. , Mooney David J.
Published: May 2015

Interactions between cells and the extracellular matrix (ECM) are known to play critical roles in regulating cell phenotype. The identity of ECM ligands presented to mesenchymal stem cells (MSCs) has previously been shown to direct the cell fate commitment of these cells. To enhance osteogenic differentiation of MSCs, alginate hydrogels were prepared that present the DGEA ligand derived from collagen I. When presented from hydrogel surfaces in 2D, the DGEA ligand did not facilitate cell adhesion, while hydrogels presenting the RGD ligand derived from fibronectin did encourage cell adhesion and spreading. However, the osteogenic differentiation of MSCs encapsulated within alginate hydrogels presenting the DGEA ligand was enhanced when compared with unmodified alginate hydrogels and hydrogels presenting the RGD ligand. MSCs cultured in DGEA‐presenting gels exhibited increased levels of osteocalcin production and mineral deposition. These data suggest that the presentation of the collagen I‐derived DGEA ligand is a feasible approach for selectively inducing an osteogenic phenotype in encapsulated MSCs. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 3516–3525, 2015.
Composites of electrospun‐fibers and hydrogels: A potential solution to current challenges in biological and biomedical field
Authors: Xu Shuxin , Deng Liandong , Zhang Jianhua , Yin Li , Dong Anjie
Published: May 2015

With increasingly rigorous requirements for biomaterials, the design and fabrication of novel materials with smart functions are urgently needed. The fabrication of composite materials that can surmount individual shortcomings as well as bring synergistic benefits represents an efficient route to improve the performances and expand application scopes of biomaterials. Due to their unique structures and properties, electrospun‐fibers and hydrogels have been widely applied in many biological and biomedical fields. Based on this, more and more attentions have been paid on the composites of electrospun‐fibers and hydrogels as biomaterials, aiming to bring their individual superiority into full play as well as remedy their intrinsic defects. This review summarizes approaches used to integrate electrospun‐fibers and hydrogels into various structures and the development of their composites as a potential solution to some current challenges in drug delivery, tissue engineering and some other bio‐related aspects. The individual roles and mutual synergy of electrospun‐fibers and hydrogels in the composites will be emphasized. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 640–656, 2016.
Phospholipid polymer electrodeposited on titanium inhibits platelet adhesion
Authors: Fukuhara Yusuke , Kyuzo Megumi , Tsutsumi Yusuke , Nagai Akiko , Chen Peng , Hanawa Takao
Published: May 2015

To develop metallic materials with thromboresistance, a block‐type copolymer (PMbA) was immobilized onto a titanium surface with electrodeposition. The polymer was composed of a poly(2‐(methacryloyloxy)ethyl phosphorylcholine (MPC)) segment and a poly(2‐aminoethylmethacrylate) segment, which was designed to electronically adsorb to the surface oxide layer on the titanium surface. We confirmed that the polymer was synthesized as expected by nuclear magnetic resonance and gel permeation chromatography. In a 0.26 mmol L−1 PMbA solution adjusted to pH 11, −3.0 V (vs. an Ag/AgCl electrode) was applied to a titanium substrate for 300 s. The immobilization of PMbA on the titanium was confirmed with X‐ray photoelectron spectroscopy and an atomic force microscope. The water contact angle and amount of adsorbed protein on the PMbA‐modified surface were decreased. Thrombus formation was not observed all over the surface even when the surface was contacted with human blood without an anticoagulant. Therefore, PMbA covered the surface with even density and poly(MPC) segments in PMbA inhibited platelet adsorption. Electrodeposition with PMbA improves the blood compatibility of a titanium substrate in a simple process. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 554–560, 2016.
Development of methacrylate/silorane hybrid monomer system: Relationship between photopolymerization behavior and dynamic mechanical properties
Authors: Song Linyong , Ye Qiang , Ge Xueping , Singh Viraj , Misra Anil , Laurence Jennifer S. , Berrie Cindy L. , Spencer Paulette
Published: May 2015

Resin chemistries for dental composite are evolving as noted by the introduction of silorane‐based composites in 2007. This shift in the landscape from methacrylate‐based composites has fueled the quest for versatile methacrylate‐silorane adhesives. The objective of this study was to evaluate the polymerization behavior and structure/property relationships of methacrylate‐silorane hybrid systems. Amine compound ethyl‐4‐(dimethylamino) benzoate (EDMAB) or silane compound tris(trimethylsilyl) silane (TTMSS) was selected as coinitiators. The mechanical properties of the copolymer were improved significantly at low concentrations (15, 25, or 35 wt %) of silorane when EDMAB was used as coinitiator. The rubbery moduli of these experimental copolymers were increased by up to 260%, compared with that of the control (30.8 ± 1.9 MPa). Visible phase separation appeared in these formulations if the silorane concentrations in the formulations were 50–75 wt %. The use of TTMSS as coinitiator decreased the phase separation, but there was a concomitant decrease in mechanical properties. In the neat methacrylate formulations, the maximum rates of free‐radical polymerization with EDMAB or TTMSS were 0.28 or 0.06 s−1, respectively. In the neat silorane resin, the maximum rates of cationic ring‐opening polymerization with EDMAB or TTMSS were 0.056 or 0.087 s−1, respectively. The phase separation phenomenon may be attributed to differences in the rates of free‐radical polymerization of methacrylates and cationic ring‐opening polymerization of silorane. In the hybrid systems, free‐radical polymerization initiated with EDMAB led to higher crosslink density and better mechanical properties under dry/wet conditions. These beneficial effects were, however, associated with an increase in heterogeneity in the network structure. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 841–852, 2016.
Keratin hydrogel carrier system for simultaneous delivery of exogenous growth factors and muscle progenitor cells
Authors: Tomblyn Seth , Pettit Kneller Elizabeth L. , Walker Stephen J. , Ellenburg Mary D. , Kowalczewski Christine J. , Van Dyke Mark , Burnett Luke , Saul Justin M.
Published: May 2015

Ideal material characteristics for tissue engineering or regenerative medicine approaches to volumetric muscle loss (VML) include the ability to deliver cells, growth factors, and molecules that support tissue formation from a system with a tunable degradation profile. Two different types of human hair‐derived keratins were tested as options to fulfill these VML design requirements: (1) oxidatively extracted keratin (keratose) characterized by a lack of covalent crosslinking between cysteine residues, and (2) reductively extracted keratin (kerateine) characterized by disulfide crosslinks. Human skeletal muscle myoblasts cultured on coatings of both types of keratin had increased numbers of multinucleated cells compared to collagen or MatrigelTMand adhesion levels greater than collagen. Rheology showed elastic moduli from 102to 105Pa and viscous moduli from 101to 104Pa depending on gel concentration and keratin type. Kerateine and keratose showed differing rates of degradation due to the presence or absence of disulfide crosslinks, which likely contributed to observed differences in release profiles of several growth factors.In vivotesting in a subcutaneous mouse model showed that keratose hydrogels can be used to deliver mouse muscle progenitor cells and growth factors. Histological assessment showed minimal inflammatory responses and an increase in markers of muscle formation. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 864–879, 2016.
In vitro bioactivity investigations of Ti‐15Mo alloy after electrochemical surface modification
Authors: Kazek‐Kęsik Alicja , Kuna Karolina , Dec Weronika , Widziołek Magdalena , Tylko Grzegorz , Osyczka Anna M. , Simka Wojciech
Published: May 2015

Titanium and its aluminum and vanadium‐free alloys have especially great potential for medical applications. Electrochemical surface modification improves their surface bioactivity and stimulates osseointegration process. In this work, the effect of plasma electrolytic oxidation of the β‐type alloy Ti‐15Mo surface on its bioactivity is presented. Bioactivity of the modified alloy was investigated by immersion in simulated body fluid (SBF). Biocompatibility of the modified alloys were tested using human bone marrow stromal cells (hBMSC) and wild intestinal strains (DV/A, DV/B, DV/I/1) of Desulfovibrio desulfuricans bacteria. The particles of apatite were formed on the anodized samples. Human BMSC cells adhered well on all the examined surfaces and expressed ALP, collagen, and produced mineralized matrix as determined after 10 and 21 days of culture. When the samples were inoculated with D. desulfuricans bacteria, only single bacteria were visible on selected samples. There were no obvious changes in surface morphology among samples. Colonization and bacterial biofilm formation was observed on as‐ground sample. In conclusion, the surface modification improved the Ti‐15Mo alloy bioactivity and biocompatibility and protected surface against colonization of the bacteria. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 903–913, 2016.
EGFR and MEK Blockade in Triple Negative Breast Cancer Cells
Authors: Maiello Monica Rosaria , D'Alessio Amelia , Bevilacqua Simona , Gallo Marianna , Normanno Nicola , De Luca Antonella
Published: May 2015

Although evidence suggests that the RAF/MEK/ERK pathway plays an important role in triple negative breast cancer (TNBC), resistance to MEK inhibitors has been observed in TNBC cells. Different mechanisms have been hypothesized to be involved in this phenomenon, including receptor tyrosine kinase‐dependent activation of the PI3K/AKT pathway. In this study, we analyzed the effects of the MEK1/2 inhibitor selumetinib in combination with the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor gefitinib in a panel of TNBC cell lines that showed different levels of sensitivity to single‐agent selumetinib: SUM‐149 and MDA‐MB‐231 cells resulted to be sensitive, whereas SUM‐159, MDA‐MB‐468 and HCC70 cells were relatively resistant to the drug. Treatment of TNBC cells with selumetinib produced an increase of the phosphorylation of the EGFR both in selumetinib‐sensitive SUM‐149, MDA‐MB‐231 and in selumetinib‐resistant MDA‐MB‐468 TNBC cells. The combination of selumetinib and gefitinib resulted in a synergistic growth inhibitory effect in all the TNBC cell lines, although the IC50 was not reached in SUM‐159 and MDA‐MB‐468 cells. This effect was associated with an almost complete suppression of ERK1/2 activation and a reduction of selumetinib‐induced AKT phosphorylation. In addition, in selumetinib‐sensitive TNBC cells the combination of selumetinib and gefitinib induced a significant G0/G1 cell cycle arrest and apoptosis. Taken together, our data demonstrated that blockade of the EGFR might efficiently increase the antitumor activity of selumetinib in a subgroup of TNBC and that this phenomenon might be related to the effects of such combination on both ERK1/2 and AKT activation. J. Cell. Biochem. 116: 2778–2785, 2015. © 2015 Wiley Periodicals, Inc.
Synthesis and Structure Elucidation of (R)‐3‐(2′‐hydroxyprop‐1‐yl) adenine
Authors: Gao Yang , Zhong Jia‐Liang , Wu Tai‐Zhi , Jin Lin‐Yong , Zhang Fu‐Li
Published: May 2015

(R)‐3‐(2′‐hydroxyprop‐1‐yl) adenine 4 was obtained by alkylation of adenine 1 with R‐propylene carbonate 2 in the presence of pulverized sodium hydroxide in the synthetic process of tenofovir. The elucidation of the structure of 4 was confirmed by single crystal X‐ray diffraction and NMR experiments such as 1D 1H, 13C, and DEPT, as well as 2D COSY, HSQC, and HMBC spectra.
Investigating the pharmacokinetics and biological distribution of silver‐loaded polyphosphoester‐based nanoparticles using 111Ag as a radiotracer
Authors: Aweda Tolulope A. , Zhang Shiyi , Mupanomunda Chiedza , Burkemper Jennifer , Heo Gyu Seong , Bandara Nilantha , Lin Mai , Cutler Cathy S. , Cannon Carolyn L. , Youngs Wiley J. , Wooley Karen L. , Lapi Suzanne E.
Published: May 2015

Purified 111Ag was used as a radiotracer to investigate silver loading and release, pharmacokinetics, and biodistribution of polyphosphoester‐based degradable shell crosslinked knedel‐like (SCK) nanoparticles as a comparison to the previously reported small molecule, N‐heterocyclic silver carbene complex analog (SCC1) for the delivery of therapeutic silver ions in mouse models. Biodistribution studies were conducted by aerosol administration of 111Ag acetate, [111Ag]SCC1, and [111Ag]SCK doses directly into the lungs of C57BL/6 mice. Nebulization of the 111Ag antimicrobials resulted in an average uptake of 1.07 ± 0.12% of the total aerosolized dose given per mouse. The average dose taken into the lungs of mice was estimated to be 2.6 ± 0.3% of the dose inhaled per mouse for [111Ag]SCC1 and twice as much dose was observed for the [111Ag]SCKs (5.0 ± 0.3% and 5.9 ± 0.8% for [111Ag]aSCK and [111Ag]zSCK, respectively) at 1 h post administration (p.a.). [111Ag]SCKs also exhibited higher dose retention in the lungs; 62–68% for [111Ag]SCKs and 43% for [111Ag]SCC1 of the initial 1 h dose were observed in the lungs at 24 h p.a.. This study demonstrates the utility of 111Ag as a useful tool for monitoring the pharmacokinetics of silver‐loaded antimicrobials in vivo.
Whole‐body MRI‐DWI for assessment of residual disease after completion of therapy in lymphoma: A prospective multicenter study
Authors: Littooij Annemieke S. , Kwee Thomas C. , de Keizer Bart , Bruin Marrie C.A. , Coma Ana , Beek Frederik J.A. , Fijnheer Rob , Nievelstein Rutger A.J.
Published: May 2015

Background

To assess the performance of whole‐body MRI including diffusion‐weighted imaging (whole‐body MRI‐DWI) for the detection of residual disease after completion of treatment in lymphoma patients.

Methods

Twenty‐six patients with lymphoma prospectively underwent whole‐body MRI‐DWI (1.5 Tesla MR) and 18F‐fluoro‐2‐deoxy‐D‐glucose positron emission tomography (FDG‐PET)/computed tomography (CT) for posttreatment evaluation which were visually assessed. Apparent diffusion coefficient (ADC) and FDG‐PET/CT standardized uptake value measurements were performed in all residual lesions. An unblinded expert panel reviewed all cases and determined the presence or absence of posttreatment residual disease using all available imaging (except for whole‐body MRI‐DWI), clinical, and histopathological information with a follow‐up of at least 6 months. The performance of whole‐body MRI‐DWI was compared with this panel reference standard.

Results

Five of 26 patients were diagnosed with residual disease. Sensitivity and specificity for detection of residual disease with whole‐body MRI‐DWI were 100% and 62%, respectively. By ROC analysis, the optimal threshold of ADC was 1.21 × 10−3 mm2/s with sensitivity and specificity of 100% and 91.7%, respectively.

Conclusion

Our initial results suggest that visual whole‐body MRI‐DWI analysis has a very good sensitivity for detecting viable residual lesions after completion of therapy but lacks specificity. ADC measurements could potentially increase the specificity of whole‐body MRI. J. MAGN. RESON. IMAGING 2015;42:1646–1655.
Environmental tobacco exposure is associated with vaccine modified measles in junior high school students
Authors: Suzuki Shuichi , Sato Kazuki , Watanabe Hiroko , Nezu Yoko , Nishimuta Toshiyuki
Published: May 2015

Vaccine modified measles (VMM) affects individuals with attenuated vaccine induced immunity. An outbreak of measles occurred in a junior high school, starting from an unvaccinated eighth‐grade student who developed natural measles and affected a majority of students who were immunized with a low potent strain of measles vaccine (TD97). To determine whether environmental tobacco smoke (ETS) exposure was associated with the development of VMM in this population, a questionnaire was used asking whether students had VMM symptoms during the outbreak and the smoking status of family members. VMM was defined in the study population as occurrence of fever and/or erythema, along with documented history of measles vaccination. A total of 513 students (85.9%) responded. Overall, the presence of in‐house smokers did not differ between VMM students (49.3%) and non‐VMM students (50.2%). However, in the ninth grade, presence of an in‐house smoker was significantly higher in the family of VMM students (54.0%) than in non‐VMM students (36.6%) (P = 0.044). Urinary cotinine levels were also measured in selected students (n = 37). Among families with at least one smoker, urinary cotinine levels were significantly higher in VMM students than in non‐VMM students (P = 0.032). Furthermore, a multivariable logistic regression analysis showed that a high urinary cotinine level (>10 ng/mg creatinine; 13.5 percentile) was associated with the development of VMM. Our findings suggest that a high level of ETS exposure may be associated with an increased risk of VMM in a population with attenuated vaccine induced immunity against measles. J. Med. Virol. 87:1853–1859, 2015. © 2015 Wiley Periodicals, Inc.
Conjugating influenza a (H1N1) antigen to n‐trimethylaminoethylmethacrylate chitosan nanoparticles improves the immunogenicity of the antigen after nasal administration
Authors: Liu Qingfeng , Zheng Xiaoyao , Zhang Chi , Shao Xiayan , Zhang Xi , Zhang Qizhi , Jiang Xinguo
Published: May 2015

As one of the most serious infectious respiratory diseases, influenza A (H1N1) is a great threat to human health, and it has created an urgent demand for effective vaccines. Nasal immunization can induce both systemic and mucosal immune responses against viruses, and it can serve as an ideal route for vaccination. However, the low immunogenicity of antigens on nasal mucosa is a high barrier for the development of nasal vaccines. In this study, we covalently conjugated an influenza A (H1N1) antigen to the surface of N‐trimethylaminoethylmethacrylate chitosan (TMC) nanoparticles (H1N1‐TMC/NP) through thioester bonds to increase the immunogenicity of the antigen after nasal administration. SDS‐PAGE revealed that most of the antigen was conjugated on TMC nanoparticles, and an in vitro biological activity assay confirmed the stability of the antigen after conjugation. After three nasal immunizations, the H1N1‐TMC/NP induced significantly higher levels of serum IgG and mucosal sIgA compared with free antigen. A hemagglutination inhibition assay showed that H1N1‐TMC/NP induced much more protective antibodies than antigen‐encapsulated nanoparticles or alum‐precipitated antigen (I.M.). In the mechanistic study, H1N1‐TMC/NP was shown to stimulate macrophages to produce IL‐1β and IL‐6 and to stimulate spleen lymphocytes to produce IL‐2 and IFN‐γ. These results indicated that H1N1‐TMC/NP may be an effective vaccine against influenza A (H1N1) viruses for use in nasal immunization. J. Med. Virol. 87:1807–1815, 2015. © 2015 Wiley Periodicals, Inc.
Microchip capillary electrophoresis with laser‐induced fluorescence combined with one‐step duplex reverse‐transcription polymerase chain reaction for the rapid detection of Enterovirus 71 and Coxsackievirus A16 in throat swab specimens
Authors: Jia Ruan , Chengjun Sun , Heng Chen , Chen Zhou , Yuanqian Li , Yongxin Li
Published: May 2015

Enterovirus 71 and Coxsackievirus A16 are the main pathogens causing hand‐foot‐mouth disease. In this paper, microchip capillary electrophoresis with laser‐induced fluorescence combined with one‐step duplex reverse transcript‐polymerase chain reaction has been developed for the detection of Enterovirus 71 and Coxsackievirus A16 in throat swab specimens. The specific reverse transcription‐polymerase chain reaction amplicons labeled with SYBR Orange were separated by microchip capillary electrophoresis and detected by laser induced fluorescence detector within 7 min. The intraday and interday relative standard deviation of migration time for DNA Marker was in the range of 1.36–2.94 and 2.78–3.96%, respectively. The detection limits were as low as 2.06 × 103 copies/mL for Enterovirus 71 and 5 × 103 copies/mL for Coxsackievirus A16. No cross‐reactivity was observed with rotavirus, astrovirus, norovirus, and adenovirus, which showed good specificity of the method. This assay was validated using 100 throat swab specimens that were detected by real‐time reverse‐transcript polymerase chain reaction in parallel and the two methods produced the same results. This study provided a rapid, sensitive and specific method for the detection of Enterovirus 71 and Coxsackievirus A16, which make a contribution to significant time and cost saving for the identification and treatment of patients.
Determination of nicotine and its metabolites accumulated in fish tissue using hydrophilic interaction liquid chromatography coupled with tandem mass spectrometry
Authors: Chang Yun‐Wei , Nguyen Hien P. , Chang Mike , Burket S. Rebekah , Brooks Bryan W. , Schug Kevin A.
Published: May 2015

The determination of nicotine and its major metabolites (cotinine and anabasine) in fish tissue was performed using liquid chromatography and tandem mass spectrometry. Marine and freshwater fish were purchased from local grocery stores and were prepared based on a quick, easy, cheap, effective, rugged, and safe sample preparation protocol. To determine the highly polar compounds, hydrophilic interaction liquid chromatography was also used. There were modest suppressions on measured nicotine signals (10%) due to the matrix effects from marine fish but no obvious effects on freshwater fish signals. Method validation was incorporated with internal standards and carried out with matrix‐matched calibration. The detection limits for nicotine, cotinine, and anabasine were 9.4, 3.0, and 1.5 ng/g in fish, respectively. Precision was quite acceptable returning less than 8% RSD at low, medium, and high concentrations. Acceptable and reproducible extraction recoveries (70–120%) of all three compounds were achieved, except for anabasine at low concentration (61%). The method was then applied to define nicotine bioaccumulation in a fathead minnow model, which resulted in rapid uptake with steady state internal tissue levels, reached within 12 h. This developed method offers a fast, easy, and sensitive way to evaluate nicotine and its metabolite residues in fish tissues.
Tracing carbon fixation in phytoplankton—compound specific and total 13C incorporation rates
Authors: Grosse Julia , van Breugel Peter , Boschker Henricus T. S.
Published: May 2015

Measurement of total primary production using 13C incorporation is a widely established tool. However, these bulk measurements lack information about the fate of fixed carbon: the production of major cellular compounds (carbohydrates, amino acids, fatty acids, and DNA/RNA) is affected by for instance nutrient availability as their C:N:P requirements differ. Here, we describe an approach to combine established methods in gas chromatography/isotope ratio mass spectrometry (GC/C‐IRMS) and recently developed methods in liquid chromatography/IRMS (LC/IRMS) to trace stable isotope incorporation into neutral carbohydrates, amino acids, and fatty acids, and compare their production to total carbon fixation rates. We conducted a trial study at stations in the North Sea where different nutrients were limiting. There was variation in the fate of fixed carbon at these sites. The majority of fixed carbon (64–71%) was incorporated into neutral carbohydrates, followed by amino acids (19–32%) and fatty acids (4–9%). The sum of carbon fixation into these three fractions accounted for 81–116% of total carbon fixation. P‐ and N‐limitation increased the biosynthesis of storage lipids and storage carbohydrates while N‐limitation decreased synthesis of amino acid proline with a concurrent increase in glutamic acid + glutamine. This new approach provides the capability to determine direct effects of resource limitation and the consequences for the physiological state of a phytoplankton community. It may thereby enable us to evaluate the overall quality of phytoplankton as a food source for higher trophic levels or trace consumption of phytoplankton through the food web.
Regenerated Cellulose Fibers Prepared from Wheat Straw with Different Solvents
Authors: Chen Jing‐Huan , Guan Ying , Wang Kun , Xu Feng , Sun Run‐Cang
Published: May 2015

Wheat straw cellulose (WSC) was simply isolated by delignification and hemicellulose‐removal processes, and then dissolved in five non‐derivatizing solvents, including N, N‐dimethylacetamide /lithium chloride, N‐methylmorpholine‐N‐oxide, 1‐butyl‐3‐methylimidazolium chloride, 1‐allyl‐3‐methylimidazolium chloride and 1‐ethyl‐3‐methylimidazolium acetate, to prepare regenerated cellulose fibers with wet spinning method. The results showed that WSC could be completely dissolved in all of the five solvents, and the chemical structure and thermal stability of the regenerated fibers were similar. However, the viscosity of the solutions, the morphology and mechanical strength of the fibers were highly depended on the type of the solvents.
Synthesis of pyrene‐capped polystyrene by free radical polymerization and its application in direct exfoliation of graphite into graphene nanosheets
Authors: Wang Haining , Chen Zhao , Xin Lanxia , Cui Jian , Zhao Shuai , Yan Yehai
Published: May 2015

It is of great practical significance to acquire pyrene‐capped polymer, which has proven an excellent dispersant of nanocarbons, in an accessible way. Taking synthesis of pyrene‐capped polystyrene (PyPS) as the example, free radical polymerization was demonstrated to be an attractive option to satisfactorily fulfill such mission. For this, a new azo‐based pyrenyl compound was designed, synthesized, and used as initiator. The molecular structure of PyPS was studied as a function of polymerization temperature and content of chain transfer agent of 1‐dodecanethiol. Following the successful synthesis, a PyPS polymer structured as 1.04 pyrene groups per chain was chosen as dispersant for preparation of graphene. The results showed that 0.2 mg/mL of PyPS in chloroform permits 67.4 μg/mL of graphene nanosheets to be prepared by liquid‐phase exfoliation of graphite. In contrast, only 8.5 μg/mL of graphene nanosheets could be obtained in pure chloroform. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 2175–2185
Application of impedance spectroscopy to detect the binding of biomolecules to biohybrid hydrogels
Authors: Posseckardt Juliane , Mertig Michael
Published: May 2015

Due to their capability to bind and release growth factors via electrostatic interactions, biohybrid hydrogels, formed by synthetic polymers and glycosaminoglycans, are of increasing interest for regenerative therapies. Bound to the hydrogel, growth factors are protected from diffusion and biodegradation. A sustained release of the growth factors promotes vascularization of engineered constructs. By means of impedance spectroscopy, we were able to detect the binding of biomolecules to the immobilized gel at nanomolar concentrations. Biomolecule binding causes the impedance of the gel to increase at characteristic frequencies that can be assigned to the electric properties of the gel and the electrode surface. By decreasing the dimensions of the interdigitated electrode array, the sensitivity to processes at the electrode surface can be increased.
The Hubbard model in the strong coupling theory at arbitrary filling
Authors: Sherman Alexei
Published: May 2015

Equations for the electron Green's function of the two‐dimensional Hubbard model, derived using the strong coupling diagram technique, are self‐consistently solved for different electron concentrations n and tight‐binding dispersions. Comparison of spectral functions calculated for the ratio of Hubbard repulsion to the nearest neighbor hopping with Monte Carlo data shows not only qualitative, but in some cases quantitative agreement in position of maxima. General spectral shapes, their evolution with momentum and filling in the wide range are also similar. At half‐filling and for the next nearest neighbor hopping constant the Mott transition occurs at , where is the initial bandwidth. This value is close to those obtained in the cases of the semi‐elliptical density of states and for . In the case and the Mott gap reaches maximum width at , and it is larger than that at for half‐filling. In all considered cases positions of spectral maxima are close to those in the Hubbard‐I approximation.
Differences in physicochemical, morphological, and structural properties between rice starch and rice flour modified by dry heat treatment
Authors: Qiu Chao , Cao Jinmiao , Xiong Liu , Sun Qingjie
Published: May 2015

The differential influence of dry heat treatment on pasting, thermal, morphological, and crystalline structural properties of glutinous rice starch (GRS) and glutinous rice flour (GRF) in a dry state for 0, 2, or 4 h at 130°C were studied. The results revealed that the viscosity and thermal stability of GRS and GRF increased after dry heat treatment. Peak viscosity of GRF rose nearly threefold from 1156 to 3145 cP. The number of disulphide bonds in GRF increased from 1.93 to 3.19 μmol/g, indicating the covalent SS linkages after dry heat treatment may result in the changes of protein structure, which may greatly influence properties of dry heated flour. Morphology of gelatinized GRS was denser, and a strong laminar structure was observed for gelatinized GRF after dry heat treatment. Fourier transformation infrared spectroscopy indicated that both GRS and GRF had relatively higher transmittance intensities in the region of 1068 and 1022 cm−1. X‐ray diffraction showed that the crystallinity of GRS increased from 32.82 to 35.02% and GRF increased from 29.32 to 34.14% after dry heat treatment. Dry heat treatment had greater effects on viscosity and structural properties of GRF than those of GRS.
Families support their children's success in science learning by influencing interest and self‐efficacy
Authors: Sha Li , Schunn Christian , Bathgate Meghan , Ben‐Eliyahu Adar
Published: May 2015

How is a child's successful participation in science learning shaped by their family's support? We focus on the critical time period of early adolescents, testing (i) whether the child's perception of family support is important for both choice preferences to participate in optional learning experiences and engagement during science learning, and (ii) whether the effects on choice preferences and engagement are mediated through effects on child interest and self‐efficacy in science. Structural equation modeling is applied to data from two different contexts, one examining engagement during a science and technology center visit and the other examining engagement and learning during classroom instruction. Models from both datasets suggest that early adolescents' perceived family support for learning is associated with their choices for and engagement in science learning, and that these effects are mediated by effects on child interest and self‐efficacy in science. Further, children's family physical resources (e.g., available learning spaces and materials) predicts their perceived family support, but is not separately connected to either interest or self‐efficacy. © 2015 Wiley Periodicals, Inc. J Res Sci Teach 53: 450–472, 2016
A coalitional game‐based relay load balancing and power allocation scheme in decode‐and‐forward cellular relay networks
Authors: Farazmand Yalda , Alfa Attahiru S.
Published: May 2015

In this paper, a game theoretic relay load balancing and power allocation scheme is proposed for downlink transmission in a decode‐and‐forward orthogonal frequency division multiple access‐based cellular relay network. A system with a base station communicating with multiple users via multiple relays is considered. The relays have limited power, which must be divided among the users they support. In traditional scheme, each relay simply divides its transmit power equally among all its users. Moreover, each user selects the relay with the highest channel gain. In this work, we do not apply the traditional relay scheme. It is because the users are distributed randomly, and by applying the traditional relay selection scheme, it may happen that some relays have more users connected to them than other relays, which results in having unbalanced load among the relays. In order to avoid performance degradation, achieve relay load balancing, and maximize the total data rate of the network, a game theoretic approach is proposed, which efficiently assigns the users to relays. The power of each relay is wisely distributed among users by the efficient power allocation scheme. Simulation results indicate that the proposed game‐based scheme can considerably improve the average sum‐spectral efficiency. Moreover, it shows that by applying the game, users who can connect to uncongested relays join them as opposed to connecting to congested relays. Copyright © 2015 John Wiley & Sons, Ltd.
The Bismuth Subiodides Bi8Pt5I3 and Bi16Pt11I6 – Layered Metals with Covalent Platinum Networks
Authors: Rasche Bertold , Schnelle Walter , Ruck Michael
Published: May 2015

Black shiny platelets of Bi8Pt5I3 and Bi16Pt11I6 were crystallized from melts of the metals and BiI3. Despite very similar compositions and close peritectics, a protocol for targeted synthesis could be developed based on differences of the decomposition pressures. Bi8Pt5I3 has a monoclinic crystal structure [space group C2/m; a = 1850.7(2) pm, b = 391.46(3) pm, c = 1340.5(1) pm, β = 113.28(1)°], in which corrugated intermetallic layers alternate with monolayers of non‐coordinating iodide ions. The platinum atoms are in square, trigonal‐prismatic, or capped trigonal‐prismatic coordination by bismuth atoms. Additional covalent bonding between platinum atoms defines flat stripes of five atoms width inside the intermetallic layer. Bi16Pt11I6 crystallizes in the acentric tetragonal space group P4212 with a = 1386.6(1) pm and c = 924.5(1) pm. Corresponding to the higher transition‐metal content, the covalent network of platinum atoms is two‐dimensional. The node connectivity in the network is three or four; the total coordination number of all platinum atoms is ten. Single layers of iodide ions separate the intermetallic layers. Two‐thirds of the iodide ions are coordinating bismuth atoms that protrude from the intermetallic layer, forming [BiI4] squares. Temperature‐dependent electrical resistivity and magnetic susceptibility measurements on polycrystalline powders indicate that Bi8Pt5I3 and Bi16Pt11I6 are diamagnetic metals. The calculated electronic band structures confirm pseudo two‐dimensional metallic character only for Bi8Pt5I3.
Directionality of electron transfer in cyanobacterial photosystem I at 298 and 77 K
Authors: Makita Hiroki , Hastings Gary
Published: May 2015

Electron transfer processes in cyanobacterial photosystem I particles from Synechocystis sp. PCC 6803 with a high potential naphthoquinone (2,3‐dichloro‐1,4‐naphthoquinone) incorporated into the A1 binding site have been studied at 298 and 77 K using time‐resolved visible and infrared difference spectroscopy. The high potential naphthoquinone inhibits electron transfer past A1, and biphasic P700+A1
− radical pair recombination is observed. The two phases are assigned to P700+A1B
− and P700+A1A
− recombination. Analyses of the transient absorption changes indicate that the ratio of A‐ and B‐branch electron transfer is 95:5 at 77 K and 77:23 at 298 K.
El Niño controls Holocene rabbit and hare populations in Baja California
Authors: Hart Isaac A. , Broughton Jack M. , Gruhn Ruth
Published: May 2015

The El Niño/Southern Oscillation (ENSO) is a major source of climatic variation worldwide, with significant impacts on modern human and animal populations. However, few detailed records exist on the long-term effects of ENSO on prehistoric vertebrate populations. Here we examine how lagomorph (rabbit and hare) deposition rate, population age structure and taxonomic composition from Abrigo de los Escorpiones, a well-dated, trans-Holocene vertebrate fauna from northern Baja California, Mexico, vary as a function of the frequency of wet El Niño events and eastern Pacific sea-surface temperatures (SSTs) derived from eastern Pacific geological records. Faunal indices vary significantly in response to El Niño-based precipitation and SST, with substantial moisture-driven variability in the middle and late Holocene. The late Holocene moisture pulse is coincident with previously documented changes in the population dynamics of other vertebrates, including humans. As the frequency and intensity of ENSO is anticipated to vary in the future, these results have important implications for change in future vertebrate populations.
Turbulent pair dispersion as a ballistic cascade phenomenology
Authors: Bourgoin Mickaël
Published: May 2015

Since the pioneering work of Richardson in 1926, later refined by Batchelor and Obukhov in 1950, it is predicted that the rate of separation of pairs of fluid elements in turbulent flows with initial separation at inertial scales, grows ballistically first (Batchelor regime), before undergoing a transition towards a super-diffusive regime where the mean-square separation grows as $t^{3}$ (Richardson regime). Richardson empirically interpreted this super-diffusive regime in terms of a non-Fickian process with a scale-dependent diffusion coefficient (the celebrated Richardson’s ‘$4/3$rd’ law). However, the actual physical mechanism at the origin of such a scale dependent diffusion coefficient remains unclear. The present article proposes a simple physical phenomenology for the time evolution of the mean-square relative separation in turbulent flows, based on a scale-dependent ballistic scenario rather than a scale-dependent diffusive. It is shown that this phenomenology accurately retrieves most of the known features of relative dispersion for particles mean-square separation, among others: (i) it is quantitatively consistent with most recent numerical simulations and experiments for mean-square separation between particles (both for the short-term Batchelor regime and the long-term Richardson regime, and for all initial separations at inertial scales); (ii) it gives a simple physical explanation of the origin of the super-diffusive $t^{3}$ Richardson regime which naturally builds itself as an iterative process of elementary short-term scale-dependent ballistic steps; (iii) it shows that the Richardson constant is directly related to the Kolmogorov constant (and eventually to a ballistic persistence parameter); and (iv) in a further extension of the phenomenology, taking into account third-order corrections, it robustly describes the temporal asymmetry between forward and backward dispersion, with an explicit connection to the cascade of energy flux across scales. An important aspect of this phenomenology is that it simply and robustly connects long-term super-diffusive features to elementary short-term mechanisms, and at the same time it connects basic Lagrangian features of turbulent relative dispersion (both at short and long times) to basic Eulerian features of the turbulent field: second-order Eulerian statistics control the growth of separation (both at short and long times) while third-order Eulerian statistics control the temporal asymmetry of the dispersion process, which can then be directly identified as the signature of the energy cascade and associated to well-known exact results as the Karman–Howarth–Monin relation.
Evaporation of sessile drops: a three-dimensional approach
Authors: Sáenz P. J. , Sefiane K. , Kim J. , Matar O. K. , Valluri P.
Published: May 2015

The evaporation of non-axisymmetric sessile drops is studied by means of experiments and three-dimensional direct numerical simulations (DNS). The emergence of azimuthal currents and pairs of counter-rotating vortices in the liquid bulk flow is reported in drops with non-circular contact area. These phenomena, especially the latter, which is also observed experimentally, are found to play a critical role in the transient flow dynamics and associated heat transfer. Non-circular drops exhibit variable wettability along the pinned contact line sensitive to the choice of system parameters, and inversely dependent on the local contact-line curvature, providing a simple criterion for estimating the approximate contact-angle distribution. The evaporation rate is found to vary in the same order of magnitude as the liquid–gas interfacial area. Furthermore, the more complex case of drops evaporating with a moving contact line (MCL) in the constant contact-angle mode is addressed. Interestingly, the numerical results demonstrate that the average interface temperature remains essentially constant as the drop evaporates in the constant-angle (CA) mode, while this increases in the constant-radius (CR) mode as the drops become thinner. It is therefore concluded that, for increasing substrate heating, the evaporation rate increases more rapidly in the CR mode than in the CA mode. In other words, the higher the temperature the larger the difference between the lifetimes of an evaporating drop in the CA mode with respect to that evaporating in the CR mode.
Hierarchy and Judicial Institutions: Arbitration and Ideology in the Hellenistic World
Authors: Grynaviski Eric , Hsieh Amy
Published: May 2015

International arbitration is a distinctive feature of both contemporary international politics and the ancient world. Explanations of arbitration in the international relations literature generally posit that states engage in arbitration to mitigate the effects of competition in an anarchical system, or that the practice of arbitration reflects democratic norms. However, an examination of arbitration during the paradigmatic case of the Hellenistic period (338–90bce) casts doubt on the existing literature. Hierarchy rather than anarchy better characterizes the political context in which arbitration took place: the Greeks often organized themselves into alliances or leagues in which a hegemon dominated decision making, or into federal states with a common foreign policy. This hierarchical setting was a necessary condition for international arbitration where the practice of arbitration was a tool to legitimize hierarchical powers. We assemble an original data set of Hellenistic arbitrations, and use qualitative comparative analysis to show that hierarchy was almost always a necessary condition for international arbitration. Process-tracing of arbitration under three political orders—hegemonic kingdoms in the Greek world, Greek federations, and the Roman Empire—shows that arbitration as a particular means of dispute resolution was used as an ideological device to build and legitimize international order. We then analyze the contemporary record, finding a role for hierarchy in modern international arbitration.
Stylet (vestigial shell) size inOctopus vulgaris(Cephalopoda) hatchlings used to determine stylet nucleus in adults
Authors: Lourenço Sílvia , Moreno Ana , Narciso Luís , Pereira João , Rosa Rui , González Ángel F.
Published: May 2015

The estimation of age and growth of cephalopod stocks is a key issue for their sustainable management. Recently, several studies have successfully validated the daily deposition of growth rings in the vestigial shell or stylets of several octopus species.Octopus vulgariseggs were incubated at two different temperatures, 18 and 22°C, until hatching to determine stylet size at hatching and assess the effect of temperature in the stylet dimensions. The 3-day-old hatchlings were sectioned transversally and 6 μm sections were stained to enhance the stylet position and visibility. The sections were observed under transmitted light microscopy at a magnification of 1000×, and the stylets identified as blue/green structures inside the mantle–funnel retractor muscle. The transversal sections of the whole paralarvae allowed the diameter of the embryonic stylet of an octopus species to be measured for the first time. The mean stylet diameter in 3-day-old paralarvae is 3.99 μm independently of the thermal conditions. Moreover, significant differences in stylet size between captive and wild paralarvae were observed; the latter showed significantly larger stylets, an indication that they are over 3 days old. Our results also indicate that the stylet nucleus is much smaller than previously thought based on measurements in stylets of juveniles and adults.
Bison with benefits: towards integrating wildlife and ranching sectors on a public rangeland in the western USA
Authors: Ranglack Dustin H. , du Toit Johan T.
Published: May 2015

The North American model of wildlife conservation, based on the public trust doctrine, is credited for the recovery of several charismatic wildlife species, including the plains bison Bison bison. In that model, wildlife is a public resource from which the private sector may not profit either individually or collectively. In recent years, however, resilience thinking is driving changes in the traditional state-run wildlife management model to allow for integrated multi-sector approaches at the landscape scale. A free-ranging herd of bison on public land in the Henry Mountains of Utah is used as a case study to consider if and how a community-based conservation programme could be developed for a state-managed wildlife resource to benefit all stakeholders. The Henry Mountains bison, which are disease-free, share the rangeland with cattle that are privately owned by individual ranchers and corporations with various economic goals and environmental values. The ranchers currently derive no benefits from the bison and have concerns regarding competition between bison and cattle. However, a threshold harvesting strategy with community participation could generate revenue to offset these concerns. It could also provide benefits to the local community, increase state revenue, and increase the size of the bison population while securing its long-term genetic viability. Implementation would initially require facilitation by policy specialists, after which we suggest a Henry Mountains bison partnership could serve as a model for bison recovery efforts elsewhere in North America.
Portraits of preperiodic points for rational maps
Authors: GHIOCA DRAGOS , NGUYEN KHOA , TUCKER THOMAS J.
Published: May 2015

Let K be a function field over an algebraically closed field k of characteristic 0, let ϕ ∈ K(z) be a rational function of degree at least equal to 2 for which there is no point at which ϕ is totally ramified and let α ∈ K. We show that for all but finitely many pairs (m, n) ∈ $\mathbb{Z}$⩾0 × $\mathbb{N}$ there exists a place $\mathfrak{p}$ of K such that the point α has preperiod m and minimum period n under the action of ϕ. This answers a conjecture made by Ingram–Silverman [13] and Faber–Granville [8]. We prove a similar result, under suitable modification, also when ϕ has points where it is totally ramified. We give several applications of our result, such as showing that for any tuple (c0, . . ., cd−2) ∈ kd−1 and for almost all pairs (mi, ni) ∈ $\mathbb{Z}$⩾0 × $\mathbb{N}$ for i = 0, . . ., d − 2, there exists a polynomial f ∈ k[z] of degree d in normal form such that for each i = 0, . . ., d − 2, the point ci has preperiod mi and minimum period ni under the action of f.