bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel synthesis of leucoside by enzymatic hydrolysis of tea seed extract
Authors: Chung Dae‐won , Lee Seul Bi
Published: July 2012

BACKGROUND: The application of tea seed extract (TSE) has been widely investigated owing to its biological activities. In this paper, two flavonol triglycosides found in TSE, camelliaside A (CamA) and camelliaside B (CamB), were subjected to hydrolysis in the presence of three commercial enzyme complexes of the Pectinex® series, 5XL, XXL and Ultra SP‐L (Ultra).

RESULTS: XXL and 5XL induced stepwise deglycosylation of CamA and CamB to yield kaempferol diglycoside (nicotiflorin), kaempferol monoglycoside (astragalin) and kaempferol, while Ultra produced an additional new compound (1) that had not been observed in earlier studies. Upon hydrolysis of isolated CamA and CamB, compound (1) was obtained only from CamB. Both the molecular ion peak in liquid chromatography/mass spectrometry and the 1H and 13C nuclear magnetic resonance spectra of (1) isolated by Ultra‐induced hydrolysis of TSE indicated that (1) was kaempferol 3‐O‐β‐xylopyranosyl (1 → 2)‐β‐glucopyranoside (leucoside), formed by selective hydrolysis of the rhamnosyl moiety of CamB.

CONCLUSION: Pure leucoside can be prepared by enzymatic partial hydrolysis of TSE. This is the first study to address the synthesis of pure leucoside from a natural source. Copyright © 2012 Society of Chemical Industry
The effects of fruit maturation, delayed storage and ethylene treatment on the incidence of low‐temperature breakdown of ‘Hayward’ kiwifruit
Authors: Koutsoflini Alexia , Gerasopoulos Dimitrios , Vasilakakis Miltiadis
Published: July 2012

BACKGROUND: Low‐temperature breakdown (LTB), a disorder inducing quality loss, during and after cold storage of ‘Hayward’ kiwifruit was investigated. Harvested kiwifruits during fruit maturation or after delayed storage (DS) at 20 °C for 0, 1, 2, 3 and 4 weeks and 1 µL L−1 ethylene treatment for 24 h were stored at − 0.5 °C for 24 weeks and additional ripening at 20 °C for 5 days. Fruit quality indices and LTB incidence and severity were determined before and after treatments.

RESULTS: Harvested fruits ripened during maturation, DS and after ethylene treatment. After storage and shelf life, fruits of all treatments were at complete ripening stage. LTB incidence of early harvested fruits was high, while that of fruits of the mid (third) and late harvests was low. Fruits of the third harvest date showed progressively increased LTB incidence with increasing duration of DS to as high as 95–100% after 4 weeks. Ethylene‐treated fruits showed a comparable increase in LTB to that corresponding to 2–3 weeks of DS.

CONCLUSION: In contrast to fruit maturation, postharvest (after harvest and before storage) DS at non‐chilling temperature and ethylene treatment advanced the ripening of ‘Hayward’ kiwifruit and resulted in increased LTB incidence. Copyright © 2012 Society of Chemical Industry
Efficacy of various naturally occurring caffeic acid derivatives in preventing post‐harvest protein losses in forages
Authors: Sullivan Michael L , Zeller Wayne E
Published: July 2012

BACKGROUND: In red clover, oxidation of endogenous o‐diphenols by polyphenol oxidase (PPO) inhibits post‐harvest proteolyis. This system is transferable to alfalfa by providing PPO (via a transgene) and o‐diphenol PPO substrates (via exogenous application). To exploit the PPO system for protein protection, it would be advantageous to produce PPO substrates in alfalfa, which lacks them. We assessed the extent of PPO‐mediated proteolytic inhibition by phenolic compounds, especially those whose biosynthesis could be engineered into alfalfa.

RESULTS: Tested compounds included o‐diphenols (caffeic acid, phaselic acid, chlorogenic acid, clovamide) and monophenols (p‐coumaric acid, p‐coumaroyl‐malic acid). In the presence of PPO, 2 mmol o‐diphenol g−1 protein reduced 24 h proteolysis 68–87% (P < 0.001) and as little as 0.25 mmol g−1 protein still decreased 24 h proteolysis 43–60% (P < 0.001). At high concentrations, clovamide inhibited 24 h proteolysis 50% (P < 0.001) in the absence of PPO, likely due to non‐PPO oxidation. Monophenol p‐coumaric acid did not inhibit 24 h proteolyis, although high levels of its malate ester did exhibit PPO‐ and oxygen‐independent inhibition (37%, P < 0.001).

CONCLUSIONS: For PPO‐mediated proteolytic inhibition, pathways for both phaselic acid and chlorogenic acid may be good targets for engineering into alfalfa. Clovamide may be useful for inhibiting proteolysis without PPO. Published 2012 by John Wiley & Sons, Ltd.
Impact of encroaching woody vegetation on nest success of upland nesting waterfowl
Authors: Thompson Sarah J. , Arnold Todd W. , Vacek Sara
Published: July 2012

Grassland managers often regard woody vegetation as hostile habitat that potentially reduces the abundance and fecundity of wildlife that use grasslands. We tested that assumption for waterfowl by examining patterns of nest success on study areas that differed in current extent and previous management of woody vegetation. We located and monitored 1,064 waterfowl nests on 33 federally owned Waterfowl Production Areas (WPAs) in western Minnesota during 2008–2010. Sites contained 0.3–15.1% woodland and also varied markedly in extent of shrubs and scattered trees. Average nest success was low (12.9%), but ranged from 1.5% to 38.7% among site‐years. Nests were more likely to succeed when located in landscapes containing more grass (500‐m scale) and fewer wetlands (100‐m scale), but none of 8 variables measuring woody vegetation were negatively associated with nest survival and 1 variable (abundance of lone trees) was positively associated with nest survival. Our results indicate that management efforts focusing on removing woody vegetation are unlikely to provide improvements in nest survival rates for breeding waterfowl, except to the extent that such management is necessary to maintain large tracts of grassland. © 2012 The Wildlife Society.
Influence of young black spruce plantations on moose winter distribution
Authors: Leclerc Martin , Lamoureux Jean , St‐Laurent Martin‐Hugues
Published: July 2012

Logging in the boreal forest may benefit moose by increasing food availability. However, the influence of tree plantations on moose behavior, especially on moose spatial ecology, is poorly understood. We assessed the impacts of black spruce plantations on moose winter distribution at a landscape scale in the Bas‐Saint‐Laurent region (Québec, Canada). We used winter aerial surveys to examine relationships among plantation characteristics and other habitat variables known to affect moose distribution. The total area of plantations positively influenced moose abundance, but highly aggregated plantations resulted in fewer moose. Moose abundance was also positively associated with food availability and the density of edges between stands providing cover and stands offering high food availability, but moose abundance was negatively associated with road density. Although plantation characteristics were less influential than habitat variables related to foraging and predator avoidance, we demonstrate that the area of black spruce plantations and their configuration should be considered in moose management. We conclude that an integrated management strategy is needed to find a balance between overdeveloped road networks (needed to join homogeneously distributed plantations) and agglomerated plantations in order to mitigate impacts on moose winter distribution. © 2012 The Wildlife Society.
The Role of Affect in the Computational Modeling ofNaturalLanguage
Authors: Alm Cecilia Ovesdotter
Published: July 2012

Expressivity is an intrinsic component of natural language. This article follows the tradition ofaffective computing(Picard 1997) in usingaffectto refer to connected concepts such as emotion, mood, feelings, personality, attitude, polarity, and related subjective phenomena. The overview clarifies the relevance of affect for linguistics and computational linguistics, summarizes useful background, outlines helpful resources, and highlights important considerations for computational modeling of affect in language and affect‐related linguistic behaviors. In addition, the article sketches unsettled debates, topics, problems, and areas in need of further exploration.
Prominence Hierarchies
Authors: Lockwood Hunter T. , Macaulay Monica
Published: July 2012

This paper surveys the prominence hierarchy, a term which we use to refer to a ranking of person and other categories of reference for a variety of grammatical purposes. This kind of hierarchy has been referred to in the literature by various names, for example person hierarchy, empathy hierarchy, animacy hierarchy, indexability hierarchy, and so on. We exemplify the set of morphosyntactic phenomena accounted for by such hierarchies, and consider assumptions about how hierarchies are structured and how they work. We also discuss suggested motivations for the existence of the hierarchy, consider whether a universal statement of the prominence hierarchy can be made, and examine whether prominence hierarchies can be considered to be a typological universal. Finally, we discuss two examples of formal approaches to data described by prominence hierarchies.
Inflammatory markers sampled by microdialysis catheters distinguish rejection from ischemia in liver grafts
Authors: Haugaa Håkon , Thorgersen Ebbe Billmann , Pharo Anne , Boberg Kirsten M. , Foss Aksel , Line Pål Dag , Sanengen Truls , Almaas Runar , Grindheim Guro , Wælgaard Lars , Pischke Soeren Erik , Mollnes Tom Eirik , Inge Tφnnessen Tor
Published: July 2012

Rejection and ischemia are serious complications after liver transplantation. Early detection is mandatory, but specific markers are largely missing, particularly for rejection. The objective of this study was to explore the ability of microdialysis catheters inserted in liver grafts to detect and discriminate rejection and ischemia through postoperative measurements of inflammatory mediators. Microdialysis catheters with a 100-kDa pore size were inserted into 73 transplants after reperfusion. After the study's completion, complement activation product 5a (C5a), C-X-C motif chemokine 8 (CXCL8), CXCL10, interleukin-1 (IL-1) receptor antagonist, IL-6, IL-10, and macrophage inflammatory protein 1β were analyzed en bloc in all grafts with biopsy-confirmed rejection (n = 12), in grafts with vascular occlusion/ischemia (n = 4), and in reference grafts with a normal postoperative course of circulating transaminase and bilirubin levels (n = 17). The inflammatory mediators were elevated immediately after graft reperfusion and decreased toward low, stable values during the first 24 hours in nonischemic grafts. In grafts suffering from rejection, CXCL10 increased significantly (P = 0.008 versus the reference group and P = 0.002 versus the ischemia group) 2 to 5 days before increases in circulating alanine aminotransferase and bilirubin levels. The area under the receiver operating characteristic curve was 0.81. Grafts with ischemia displayed increased levels of C5a (P = 0.002 versus the reference group and P = 0.008 versus the rejection group). The area under the curve was 0.99. IL-6 and CXCL8 increased with both ischemia and rejection. In conclusion, CXCL10 and C5a were found to be selective markers for rejection and ischemia, respectively. Liver Transpl, 2012. © 2012 AASLD.
Maximizing donor potential: Evolving organ procurement organization metrics and optimizing organ distribution and allocation in the United States
Authors: Washburn Kenneth
Published: July 2012

Key Points

1. Comprehend the basis for liver allocation and distribution in the United States.

2. Understand potential solutions to organ inequalities in the United States.

3. Understand the metrics used to assess the performance of organ procurement organizations. Liver Transpl, 2012. © 2012 AASLD.
Design and Photonic Properties of Novel Fluorinated Copolymers Bearing Phthalocyanine Side Groups
Authors: Tillet Guillaume , De Leonardis Piero , Alaaeddine Ali , Umeda Masashi , Mori Satoru , Shibata Norio , Aly Shawkat M. , Fortin Daniel , Harvey Pierre D. , Ameduri Bruno
Published: July 2012

The design and characterization of amorphous alternating copolymers endowed with a satisfactory thermal stability are reported. These alternating poly(CTFE‐alt‐CEVE) copolymers are synthesized by radical copolymerization of chlorotrifluoroethylene (CTFE) with 2‐chloroethyl vinyl ether (CEVE), which are first modified into poly[CTFE‐alt‐(2‐iodoethyl vinyl ether)] copolymers and then azidated in high yields. Alkynyl CF3‐containing phthalocyanines (Pcs) are then grafted via a copper‐catalyzed Huisgen dipolar 1,3‐addition (“grafting onto”), hence providing fluorinated copolymers with different degrees of grafting (from 10 to 72%) of Pc dangling groups. Electronic spectral (absorption, excitation, and fluorescence) and photophysical properties (fluorescence lifetimes, τF, and quantum yields, ΦF) are evaluated.
New Complex Crystals of Chiral Poly(L‐lactic acid) and Different Tactic Poly(methyl methacrylate)
Authors: Woo Eamor M. , Wang Yu‐Hsiang
Published: July 2012

Based on evidence from differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction (WAXD), and Fourier‐transform infrared (FTIR) spectroscopy, a new stereocomplex crystal (DSC Tm = 175 °C, with WAXD 2θ = 10.0° and 12.5°) is proven for the first time between structurally dissimilar chiral poly(L‐lactic acid) (PLLA) and syndiotactic poly(methyl methacrylate) (sPMMA). There is a strong complexing capacity only between low molecular weight PLLA and sPMMA, in miscible state, at specific weight fractions (70:30). The complexing capacity is more significant when the mixtures are melt‐crystallized at Tc = 110 °C or lower, and the intensity of this complex can be further enhanced if it is annealed between 100 and 160 °C, below its Tm = 175 °C. The new complex crystal can be formed only between PLLA and sPMMA, but not with isotactic or atactic PMMA.
A Highly Efficient Self‐Assembly of Responsive C2‐Cyclohexane‐Derived Gelators
Authors: Feng Chuan‐Liang , Dou Xiaoqiu , Zhang Di , Schönherr Holger
Published: July 2012

The rational design and synthesis of a family of effective low‐molecular‐weight gelators (LMWGs) with a modular architecture based on a C2‐1,4‐diamide cyclohexane core are reported. Due to the high symmetry, the gelators are initially well distributed in solution and no trapped aggregates are formed before the assembly is triggered. The subsequent self‐assembly process, which results in the formation of versatile gels, is highly efficient and can be triggered and tuned due to its remarkable dependence on the pH of solution. The assembly of different gelators is found to be closely related to the pKa of the corresponding functional substituents on the LMWGs. Primary cell culture experiments reveal that the hydrogels made under physiological conditions are promising as potential tailor‐made microenvironments.
Theory of Light‐Induced Deformation of Azobenzene Elastomers
Authors: Toshchevikov V.P. , Saphiannikova M. , Heinrich G.
Published: July 2012

Summary: A microscopic theory is proposed to describe light‐induced deformation of photo‐sensitive elastomers bearing azobenzene chromophores in their strands. We use an orientation approach in which it is assumed that the light‐induced deformation is caused by reorientation of azobenzene chromophores with respect to the electric vector of the linearly polarized light, E, due to the trans‐cis‐trans photoisomerizaion process whose efficiency depends on the orientation of the chromophores with respect to the vector E. In the framework of the Gaussian approximation for elasticity of network strands it is shown that the value of the light‐induced deformation depends on the chemical structure of network strands, namely, on the orientation distribution of chromophores around the main chains which is related to the length and elasticity of spacers. Depending on the chemical structure, azobenzene elastomers can demonstrate expansion or uniaxial contraction along the vector E, as well as non‐monotonic deformation with increasing light intensity (expansion at small light intensities and contraction at high ones).
Modeling of Structure and Nonlinear Optical Activity of Epoxy‐Based Oligomers with Dendritic Multichromophore Fragments
Authors: Fominykh Olga D. , Balakina Marina Yu.
Published: July 2012

Summary:Epoxy‐based oligomers having length up to four units with dendritic chromophore‐containing fragments covalently attached through spacers to the bearing chain are studied. The structure of the oligomers was obtained in the course of conformational search by Monte‐Carlo method, the distribution of the torsion angles values in the dendritic fragment was examined by molecular dynamics. The nonlinear‐optical response of the studied oligomers and dendritic chromophore fragments was calculated by the TDHF method at AM1 level. Intradendron cross‐linking of chromophore groups is investigated, diphenylmethandiisocyanate used as hardening agent. Cross‐linking is shown to decrease the angles between the chromophores in the dendron, thus providing enhanced nonlinear‐optical characteristics of the oligomer. Stacking‐like arrangement of chromophore groups, observed in variety of oligomers, is investigated in the framework of topological analysis of electron charge density, and Van‐der‐Waals interactions are found to be responsible for the stacking effect.
A New Approach to the Determination of Adhesion Properties of Polymer Networks
Authors: Bogdanova Yulia G. , Dolzhikova Valentina D. , Karzov Ilya M. , Alentiev Alexander Yu.
Published: July 2012

Summary: A new approach for the determination and comparison of adhesion properties of polymer networks was proposed. One permits to optimize the choice of polymers for composite materials with inorganic fibers (at the absence of binder diffusion to the fiber). For the first time the works of adhesion of polymer to liquids simulating polar or non‐polar phases were used for prediction of adhesive properties of network (binder, coupling agent) and for the choice of network provided the best tensile strength of composite material. The correctness of proposed approach was experimentally proved by measuring of tensile strength micro plastics.
Autoadhesion of Glassy Polymers
Authors: Boiko Yuri M.
Published: July 2012

Summary: Thick bulk films of linear amorphous polymers with different chain architecture and molecular weight were brought into contact with themselves in a lap‐shear joint geometry at bonding temperatures (T) below the glass transition temperatures of their bulk (T), at a small contact pressure, in order to form autoadhesive joints. As‐bonded joints were shear‐fractured in tension at ambient temperature, and their lap‐shear strength was measured as a function of T, bonding time and molecular weight. The kinetics of the process of the development of the lap‐shear strength at T < T was investigated, and the molecular mechanisms governing this process were discussed. The quasi‐equilibrium surface glass transition temperatures of the investigated polymers were estimated and compared with the corresponding values of T.
Decreased systemic IGF‐1 in response to calorie restriction modulates murine tumor cell growth, nuclear factor‐κB activation, and inflammation‐related gene expression
Authors: Harvey Alison E. , Lashinger Laura M. , Otto Glen , Nunez Nomeli P. , Hursting Stephen D.
Published: July 2012

Calorie restriction (CR) prevents obesity and has potent anticancer effects associated with altered hormones and cytokines. We tested the hypothesis that CR inhibits MC38 mouse colon tumor cell growth through modulation of hormone‐stimulated nuclear factor (NF)‐κB activation and protumorigenic gene expression. Female C57BL/6 mice were randomized (n = 30/group) to receive control diet or 30% CR diet. At 20 wk, 15 mice/group were killed for body composition analysis. At 21 wk, serum was obtained for hormone analysis. At 22 wk, mice were injected with MC38 cells; tumor growth was monitored for 24 d. Gene expression in excised tumors and MC38 cells was analyzed using real‐time RT‐PCR. In vitro MC38 NF‐κB activation (by p65 ELISA and immunofluorescence) were measured in response to varying IGF‐1 concentrations (1–400 ng/mL). Relative to controls, CR mice had decreased tumor volume, body weight, body fat, serum IGF‐1, serum leptin, and serum insulin, and increased serum adiponectin (P < 0.05, each). Tumors from CR mice, versus controls, had downregulated inflammation‐ and/or cancer‐related gene expression, including interleukin (IL)‐6, IL‐1β, tumor necrosis factor‐α, cyclooxygenase‐2, chemokine (C–C motif) ligand‐2, S100A9, and F4/80, and upregulated 15‐hydroxyprostaglandin dehydrogenase expression. In MC38 cells in vitro, IGF‐1 increased NF‐κB activation and NF‐κB downstream gene expression (P < 0.05, each). We conclude that CR, in association with reduced systemic IGF‐1, modulates MC38 tumor growth, NF‐κB activation, and inflammation‐related gene expression. Thus, IGF‐1 and/or NF‐κB inhibition may pharmacologically mimic the anticancer effects of CR to break the obesity–colon cancer link. © 2012 Wiley Periodicals, Inc.
Reversible generalized dystonia and encephalopathy from thiamine transporter 2 deficiency
Authors: Serrano Mercedes , Rebollo Mónica , Depienne Christel , Rastetter Agnès , Fernández‐Álvarez Emilio , Muchart Jordi , Martorell Loreto , Artuch Rafael , Obeso José A. , Pérez‐Dueñas Belén
Published: July 2012

Background:

Thiamine transporter‐2 deficiency, a condition resulting from mutations in the SLC19A3 gene, has been described in patients with subacute dystonia and striatal necrosis. The condition responds extremely well to treatment with biotin and has thus been named biotin‐responsive basal ganglia disease. Recently, this deficiency has also been related to Wernicke's‐like encephalopathy and atypical infantile spasms, showing heterogeneous responses to biotin and/or thiamine.

Methods:

Two Spanish siblings with a biotin‐responsive basal ganglia disease phenotype and mutations in SLC19A3 presented with acute episodes of generalized dystonia, rigidity, and symmetrical lesions involving the striatum, midline nuclei of the thalami, and the cortex of cerebral hemispheres as shown by magnetic resonance imaging.

Results:

The clinical features resolved rapidly after thiamine administration.

Conclusions:

Despite the rarity of thiamine transporter–2 deficiency, it should be suspected in patients with acute dystonia and basal ganglia injury, as thiamine can halt disease evolution and prevent further episodes. © 2012 Movement Disorder Society
Increased vessel depiction of the carotid bifurcation with a specialized 16‐channel phased array coil at 3T
Authors: Tate Quinn , Kim Seong‐Eun , Treiman Gerald , Parker Dennis L. , Hadley J. Rock
Published: July 2012

The purpose of this work was to design and construct a multichannel receive‐only radiofrequency coil for 3T magnetic resonance imaging of the human carotid artery and bifurcation with optimized signal‐to‐noise ratio (SNR) in the carotid vessels along the full extent of the neck. A neck phantom designed to match the anatomy of a subject with a neck representing the body habitus often seen in subjects with carotid arterial disease was constructed. Sixteen circular coil elements were arranged on a semirigid fiberglass former that closely fit the shape of the phantom, resulting in a 16‐channel bilateral phased array coil. Comparisons were made between this coil and a typical 4‐channel carotid coil in a study of 10 carotid vessels in five healthy volunteers. The 16‐channel carotid coil showed a 73% average improvement in SNR at the carotid bifurcation. This coil also maintained an SNR greater than the peak SNR of the 4‐channel coil over a vessel length of 10 cm. The resulting increase in SNR improved vessel depiction of the carotid arteries over an extended field of view, and demonstrated better image quality for higher parallel imaging reduction factors compared to the 4‐channel coil. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
In vitro and in vivo studies of 17O NMR sensitivity at 9.4 and 16.4 T
Authors: Lu Ming , Zhang Yi , Ugurbil Kamil , Chen Wei , Zhu Xiao‐Hong
Published: July 2012

In vivo 17O magnetic resonance spectroscopy has been successfully applied for imaging the cerebral metabolic rate of oxygen consumption through the detection of metabolically produced H217O from the inhaled 17O‐labeled oxygen in animals at high field. In this study, we compared the 17O sensitivity for detecting natural abundance H217O signals from a phantom solution and rat brains at 9.4 and 16.4 T. The 17O signal‐to‐noise ratio measured at 16.4 T was 2.9‐ and 2.7–2.8‐fold higher than that at 9.4 T for the phantom and rat brain studies, respectively. Similarly, three‐dimensional 17O magnetic resonance spectroscopy imaging data showed a more than 2.7‐fold higher signal‐to‐noise ratio in the central rat brain region at 16.4 T than that at 9.4 T. The substantial 17O signal‐to‐noise ratio gain at ultrahigh field significantly improved the reliability for imaging the cerebral metabolic rate of oxygen consumption and will provide an opportunity for in vivo assessment of altered oxidative metabolism associated with brain functions and neurological diseases. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
Den Alltag durchdrungen
Authors: Bengs Holger , Eckensberger David
Published: July 2012

Auf den Deutschen Biotechnologietagen in Frankfurt präsentierten sich die Unternehmen munter. Der schwache Kapitalmarkt ist verdaut. Die Branche wächst moderat.
New petroleum absorbers based on cardanol‐furfuraldehyde magnetic nanocomposites
Authors: Varela A. , Oliveira G. , Souza F.G. , Rodrigues C.H.M. , Costa M.A.S.
Published: July 2012

Cardanol‐furfuraldehyde/maghemite composites were prepared through a bulk polymerization aiming to produce magnetic green resins able to absorb petroleum spilled on the water. Several techniques such as Fourier transform infrared spectroscopy, ultraviolet–visible spectrophotometry, wide angle X‐ray scattering, and small angle X‐ray scattering were used in the characterization of the materials. In addition, magnetic force and oil removal capability tests were also performed. Obtained materials presented a good magnetic force allied with a considerable oil removal capability: each gram of the resin was able to remove 10g of petroleum from the water. Therefore, the easy and simple production process presented is a promising tool for oil spill cleanup process. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Comparison of flocculated and dispersed single‐wall carbon nanotube‐based coatings using nonionic surfactants
Authors: Prichard Todd D. , Vogt Bryan D.
Published: July 2012

Single‐wall carbon nanotubes (SWNTs) are promising filler materials for advanced polymer composites, but the impressive properties that have been predicted theoretically have not been realized experimentally. This gap is generally attributed to aggregation and nonideal dispersion of the SWNTs. Here, nonionic surfactants based on poly(ethylene oxide) are used to disperse SWNTs in either water or ethanol using sonication. The dispersed aqueous SWNTs are stable, while the analogous ethanol system yields loosely flocculated SWNTs. After drying these dispersions, the electrical conductivity of the flocculated system is at least an order of magnitude greater than the dispersed system at the same SWNT loading with conductivity greater than 20 S/cm obtained for the flocculated systems containing unsorted, commercial SWNTs. These flocculated systems can be readily sprayed to create conductive coatings. Despite their high electrical conductivity, these coatings provide only modest electromagnetic interference shielding (<20 dB) when testing large areas (30.5 × 30.5 cm2), which suggests significant heterogeneity or defects in these coatings that are not readily visible by eye or scanning electron microscopy. This defect mechanism is consistent with a decrease in shield efficacy at high SWNT loadings, despite no statistical change in the electrical conductivity of the coating. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
High‐density polyethylene nanocomposites using masterbatches of chlorinated polyethylene/graphene oxide
Authors: Chaudhry A.U. , Mittal Vikas
Published: July 2012

Graphene‐based nanocomposites were generated by solution mixing of the graphene oxide filler with chlorinated polyethylene compatibilizers followed by melt mixing of the solution mixed masterbatches with high‐density polyethylene. Compatibilizers with two different chlorination contents were used in different amounts in order to analyze their effect on the morphology and properties of resulting nanocomposites. Peak melting point as well as overall crystallinity was affected by graphene oxide as well as compatibilizers. Compatibilizer with higher chlorination content also interacted with polar graphene oxide surface more effectively thus leading to better filler dispersion in the composites. The addition of compatibilizers to the composites resulted in their shear and processing stability at higher angular frequencies and temperature, which otherwise was not possible for pure polymer as well as composites without compatibilizer. The mechanical performance of the nanocomposites at ambient conditions was also affected by the factors like filler delamination, plasticization of the matrix, compatibilizer content as well as their chlorination level and amorphous/semicrystalline nature. An increase of 16% in tensile modulus and 21% in strength of the composites with 5 wt% of 25% chlorinated compatibilizer at 0.5 wt% graphene oxide content was observed. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Continuous polymerization of methyl methacrylate in a taylor‐couette reactor. I. Influence of fluid dynamics on monomer conversion
Authors: Liu Zhen , Jin Tao , Kind Matthias
Published: July 2012

A Taylor‐Couette reactor offers certain advantages for continuous polymerization over other reactor types. These advantages are its rather narrow residence time distribution (series of vortices) and its good heat transfer characteristics. Hydrodynamics in this type of reactor can be controlled by its geometry (diameter, gap, width, length) and its operational parameters (rotational speed, mean residence time, viscosity). In this article, a model is presented which is suited to answer the question of how hydrodynamics influences the productivity of a continuously operated Taylor‐Couette polymerization reactor. To this end, productivity is quantified by the rate of monomer conversion. The model is specified and experimentally validated for the free radical polymerization of methyl methacrylate with the solvent xylene and 2,2‐azoisobutyronitrile as the initiator. The model considers the following four phenomena: (i) Macromixing between the vortex cells is accounted for by an axial dispersion model. (ii) The dependence of viscosity on monomer conversion along the reactor is described by a viscosity model. (iii) Polymerization kinetics and its dependence on hydrodynamics are correlated from experimental data. (iv) The dependence of segregation index Is on the local energy dissipation is used to characterize micromixing within the vortices. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Investigation of the in Vitro Metabolism of Evodiamine: Characterization of Metabolites and Involved Cytochrome P450 Isoforms
Authors: Sun Hong‐Zhi , Fang Zhong‐Ze , Cao Yun‐Feng , Sun Xiao‐Yu , Hong Mo
Published: July 2012

Evodiamine is the main active alkaloid of Evodia rutaecarpa (E. rutaecarpa) and has been demonstrated to exhibit many pharmacological activities including vasorelaxation, uterotonic action, anoxia and control of body temperature. The present study focused on the metabolism of evodiamine. Human and phenobarbital‐induced rat liver microsomal incubation of evodiamine in the presence of NADPH resulted in the formation of five major metabolites (M‐1, M‐2, M‐3, M‐4, M‐5). Four metabolites (M‐1, M‐2, M‐3 and M‐5) were identified to mono‐hydroxylated evodiamine and one metabolite (M‐4) was identified to be N‐demethylated evodiamine. CYP3A4, CYP2C9 and CYP1A2 were identified to be the main CYP isoforms involved in the metabolism of evodiamine in human liver microsomes. Finding new metabolites can help us decipher novel substance basis of efficiency and toxicity. Elucidation of drug metabolizing enzymes will facilitate explaining the individual difference for response to the same drugs or herbs and the potential drug–drug interaction or herb–drug interaction. Taken together, these results are of significance for better understanding the pharmacokinetic behaviour of evodiamine and helpful for clinical application of evodiamine and E. rutaecarpa. Copyright © 2012 John Wiley & Sons, Ltd.
A Novel Application of Plasmonics: Plasmon‐Driven Surface‐Catalyzed Reactions
Authors: Sun Mengtao , Xu Hongxing
Published: July 2012

The first experimental and theoretical evidence of the surface‐catalyzed reaction of p,p′‐dimercaptoazobenzene (DMAB) produced from para‐aminothiophenol (PATP) by local surface plasmons was reported in 2010, and since that time a series of investigations have supported these findings using different experimental and theoretical methods. Recent work has also found that local plasmons can drive a surface‐catalyzed reaction of DMAB converted from 4‐nitrobenzenethiol (4NBT), assisted by local surface plasmons. There are at least three important discoveries in these investigations: 1) in the field of surface‐enhanced Raman scattering (SERS) the widely accepted misinterpretation (since 1994) that the chemical mechanism resulting in three additional Raman peaks of PATP in Ag or Au solutions has been corrected with a new mechanism; 2) it is confirmed that SERS is not always a noninvasive technique, and under certain conditions cannot always obtain the vibrational fingerprint information of the original surface species; 3) a novel method to synthesize new molecules, induced by local surface plasmons or plasmon waveguides on the nanoscale, has been found. This Review considers recent novel applications of plasmonics to chemical reactions, especially to plasmon‐driven surface‐catalyzed reactions.
Importance‐based data transmission optimization in multi‐source single‐sink wireless sensor networks
Authors: An Wei , Lin Jiajun , Shao Fang‐Ming , Luo Haiyan , Ci Song , Wu Dalei
Published: July 2012

Energy‐efficient routing becomes one of the most critical technologies for sustaining the overall network lifetime of wireless sensor networks. In this paper, we propose a novel data transmission scheme between a number of specified source nodes and the single sink, which can efficiently restrict the usage frequency of each relay node, measured by the number of source nodes using it for data transmission. On the basis of the importance of source nodes that is closely related to deployed location, they form a descending sequence such that each node finds the minimum energy path earlier than the succeeding one. Then, the energy‐efficient multiple path algorithm with the computational complexity of O(n3) is developed for deriving the minimum energy paths, where n is the number of nodes in the network. Also, a polynomial algorithm is presented for deriving the range of the feasible values of N0 serving as the threshold of the usage frequency of relay nodes, in which each can guarantee the existence of the solution. Further, we theoretically investigate the existence of the solution and the tree‐structured solution using m‐ary tree. Extensive simulation results show that our proposed scheme can achieve significant performance enhancement. Copyright © 2012 John Wiley & Sons, Ltd.
Simulating the dynamics of wind turbine blades: part II, model validation and uncertainty quantification
Authors: Van Buren Kendra L. , Mollineaux Mark G. , Hemez François M. , Atamturktur Sezer
Published: July 2012

Verification and validation (V&V) offers the potential to play an indispensable role in the development of credible models for the simulation of wind turbines. This paper highlights the development of a three‐dimensional finite element model of the CX‐100 wind turbine blade. The scientific hypothesis that we wish to confirm by applying V&V activities is that it is possible to develop a fast‐running model capable of predicting the low‐order vibration dynamics with sufficient accuracy. A computationally efficient model is achieved by segmenting the geometry of the blade into six sections only. It is further assumed that each cross section can be homogenized with isotropic material properties. The main objectives of V&V activities deployed are to, first, assess the extent to which these assumptions are justified and, second, to quantify the resulting prediction uncertainty. Designs of computer experiments are analyzed to understand the effects of parameter uncertainty and identify the significant sensitivities. A calibration of model parameters to natural frequencies predicted by the simplified model is performed in two steps with the use of, first, a free–free configuration of the blade and, second, a fixed–free configuration. This two‐step approach is convenient to decouple the material properties from parameters of the model that describe the boundary condition. Here, calibration is not formulated as an optimization problem. Instead, it is viewed as a problem of inference uncertainty quantification where measurements are used to learn the uncertainty of model parameters. Gaussian process models, statistical tests and Markov chain Monte Carlo sampling are combined to explore the (true but unknown) joint probability distribution of parameters that, when sampled, produces bounds of prediction uncertainty that are consistent with the experimental variability. An independent validation assessment follows the calibration and is applied to mode shape vectors. Despite the identification of isolated issues with the simulation code and model developed, the overarching conclusion is that the modeling strategy is sound and leads to an accurate‐enough, fast‐running simulation of blade dynamics. This publication is Part II of a two‐part effort that highlights the V&V steps required to develop a robust model of a wind turbine blade, where Part I emphasizes code verification and the quantification of numerical uncertainty. Approved for unlimited public release on August 26, 2011, LA‐UR‐11‐4997. Copyright © 2012 John Wiley & Sons, Ltd.
Critical factors for high temperature processing of biomass from agriculture and energy crops to biofuels and bioenergy
Authors: Arvelakis Stelios , Koukios Emmanuel G.
Published: July 2012

The demand for biomass for the production of energy in the forms of electric power, heat, and liquid fuels is growing fast over the last few years worldwide, mainly due to environmental concerns regarding the use of fossil fuels, such as coal, and oil. Agricultural residues, such as wheat straw, olive residue, and corn stover, as well as energy crops, e.g., Arundo donax, miscanthus, and switchgrass gain more and more interest as feedstocks to supply the vast amounts of biomass needed in order to produce the energy and liquid fuels required to fulfill the Kyoto protocol and reduce the environmental burdens of using fossil fuels in our planet. Biomass feedstocks can be converted to energy vectors in high‐efficiency thermochemical systems, such as pressurized fluidized bed boilers and gasifiers coupled with Fischer–Tropsch or other types of liquid fuel synthesis units, supercritical combustion units, and entrained flow combustors or gasifiers. This use is presently limited by the ash‐related problems associated with high‐temperature/high‐pressure environments. Inorganic bioresource constituents, such as alkali metals, chlorine, sulfur, and phosphorus, are the most troublesome elements responsible for several problems occurring. This paper presents a critical discussion regarding the main factors affecting the use of biomass of both agricultural residues and energy crops in high temperatures and high‐efficiency thermochemical conversion systems for the production of energy and liquid fuels. On the basis of an analysis of the particular problems, we identify solutions that could resolve these problems and assist significantly with a much higher production of energy and fuels from various biomass sources in an economical and sustainable way.

This article is categorized under:

Bioenergy > Science and Materials

Energy Policy and Planning > Science and Materials
Breeding of lager yeast with Saccharomyces cerevisiae improves stress resistance and fermentation performance
Authors: Sanchez Rosa Garcia , Solodovnikova Natalia , Wendland Jürgen
Published: July 2012

Lager beer brewing relies on strains collectively known as Saccharomyces carlsbergensis, which are hybrids between S. cerevisiae and S. eubayanus‐like strains. Lager yeasts are particularly adapted to low‐temperature fermentations. Selection of new yeast strains for improved traits or fermentation performance is laborious, due to the allotetraploid nature of lager yeasts. Initially, we have generated new F1 hybrids by classical genetics, using spore clones of lager yeast and S. cerevisiae and complementation of auxotrophies of the single strains upon mating. These hybrids were improved on several parameters, including growth at elevated temperature and resistance against high osmolarity or high ethanol concentrations. Due to the uncertainty of chromosomal make‐up of lager yeast spore clones, we introduced molecular markers to analyse mating‐type composition by PCR. Based on these results, new hybrids between a lager and an ale yeast strain were isolated by micromanipulation. These hybrids were not subject to genetic modification. We generated and verified 13 hybrid strains. All of these hybrid strains showed improved stress resistance as seen in the ale parent, including improved survival at the end of fermentation. Importantly, some of the strains showed improved fermentation rates using 18°Plato at 18–25°C. Uniparental mitochondrial DNA inheritance was observed mostly from the S. cerevisiae parent. Copyright © 2012 John Wiley & Sons, Ltd.
Evaluation of Alginate and Hyaluronic Acid for Their Use in Bone Tissue Engineering
Authors: Rubert M. , Alonso-Sande M. , Monjo M. , Ramis J. M.
Published: July 2012

In this study, we compared the structural and physicochemical properties of different concentrations of alginate and high molecular weight hyaluronic acid (HA) hydrogels and their biocompatibility and bioactivity after long-term culture with MC3T3-E1 cells. Both hydrogels were biocompatible and supported long-term viability and cell proliferation. Alginate induced higher alkaline phosphatase (ALP) activity levels than HA. Calcium content was increased in concentration dependent manner in cells cultured with alginate compared to control. Culture with HA hydrogels reduced alkaline phosphatase (Alp), bone sialoprotein (Bsp) and osteocalcin (Oc), while alginate increased Oc mRNA levels. Unmodified alginate hydrogels supported osteoblast differentiation better than HA hydrogels, suggesting that alginates are more suitable for biomaterial applications in bone tissue engineering.
Close relationships and attributions for peer victimization among late adolescents
Authors: Chen Xiaochen , Graham Sandra
Published: July 2012

This study examined the effect of close relationships (best friendship and romantic relationship) on late adolescents' casual attributions for peer victimization. A total of 1106 twelfth grade students completed self‐report measures of perceived peer victimization, self‐blame attribution, psychological maladjustment (loneliness and social anxiety), and quality of close peer relationships. Results indicated that self‐blame partly mediated the link between peer victimization and psychological maladjustment. Relationship quality moderated the victimization–self‐blame relation. Participants were more likely to endorse self‐blame attributions for peer victimization when they had a negative relationship with a best friend or romantic partner. The moderated effect of negative best friendship quality was only significant for girls, whereas the moderated effect of negative romantic relationship quality was only significant for boys. Implications of these findings for future research on close relations during adolescence and for interventions to reduce the effects of peer victimization were discussed.
Substrate‐induced conformational changes in sarcoplasmic reticulum Ca2+‐ATPase probed by surface modification using diethylpyrocarbonate with mass spectrometry
Authors: Narumi Ryouhei , Yamamoto Taibo , Inoue Akio , Arata Toshiaki
Published: July 2012

We have identified 15 residues from the surface of sarcoplasmic reticulum Ca2+‐pump ATPase, by mass spectrometry using diethylpyrocarbonate modification. The reactivity of 9 residues remained high under all the conditions. The reactivity of Lys‐515 at the nucleotide site was severely inhibited by ATP, whereas that of Lys‐158 in the A‐domain decreased by one‐half and increased by five‐fold in the presence of Ca2+ and MgF4, respectively. These are well explained by solvent accessibility, pK
a and nearby hydrophobicity of the reactive atom on the basis of the atomic structure. However, the reactivity of 4 residues near the interface among A‐, N‐ and P‐domain suggested larger conformational changes of these domains in membrane upon binding of Ca2+ (Lys‐436), ATP (Lys‐158) and MgF4 (His‐5, ‐190, Lys‐436).
miR395 is a general component of the sulfate assimilation regulatory network in Arabidopsis
Authors: Matthewman Colette A. , Kawashima Cintia G. , Húska Dalibor , Csorba Tibor , Dalmay Tamas , Kopriva Stanislav
Published: July 2012

In plants, microRNAs play an important role in many regulatory circuits, including responses to environmental cues such as nutrient limitations. One such microRNA is miR395, which is strongly up‐regulated by sulfate deficiency and targets two components of the sulfate uptake and assimilation pathway. Here we show that miR395 levels are affected by treatments with metabolites regulating sulfate assimilation. The precursor of cysteine, O‐acetylserine, which accumulates during sulfate deficiency, causes increase in miR395 accumulation. Feeding plants with cysteine, which inhibits sulfate uptake and assimilation, induces miR395 levels while buthionine sulfoximine, an inhibitor of glutathione synthesis, lowers miR395 expression. Thus, miR395 is an integral part of the regulatory network of sulfate assimilation.
Self-Discrepancies and the Situational Domains of Social Phobia
Authors: Johns Adam , Peters Lorna
Published: July 2012

The present study explored whether particular discrepancies among an individual's self-beliefs, as described by Higgins’ (1987) Self-Discrepancy Theory, were differentially related to the two broad situational domains of social anxiety: performance and social interaction anxiety. Fifteen people (4 males) with a primary diagnosis of GSP from Macquarie University's Emotional Health Clinic, and 25 undergraduate psychology students from Macquarie University (8 males) with mean chronological ages of 31.7 and 20.6 years respectively, participated in the study. As predicted, the study found that the ‘actual/other:ought/other’ self-discrepancy was uniquely related to performance anxiety, the ‘actual/own:ought/other’ self-discrepancy was uniquely associated with social interaction anxiety, and the ‘actual/own:ideal/own’ self-discrepancy was uniquely associated with depression. The results are discussed in terms of their unique contribution to Self-Discrepancy Theory research, the current empirical debate regarding the existence of subtypes within social phobia, and their implications for the cognitive models and treatment of social anxiety.