bluuebunny/crossref_metadata_2025 huggingface dataset:
In Situ TEM Investigations on Thermoelectric Bi2Te3/Sb2Te3 Multilayers
Authors: Schürmann Ulrich , Winkler Markus , König Jan D. , Liu Xi , Duppel Viola , Bensch Wolfgang , Böttner Harald , Kienle Lorenz
Published: October 2011

In this work, the impact of heat treatment on the real structure of Bi2Te3/Sb2Te3 multilayers is investigated. The material was heated in situ in the transmission electron microscope (TEM) and ex situ inside a furnace after preparing these layers with the so‐called nanoalloying deposition technique via molecular beam epitaxy (MBE) equipment. The samples were prepared as a lamella for TEM studies using focused ion beam technique. EDX elemental mapping and high angle annular dark field mode‐STEM were performed to monitor changes of the morphology and interdiffusion phenomena after heating up to 250 °C. A grain growth started during heating and the chemical layer structure was smeared out partly but remained in several grains and was found to be adjusted parallel to a major lattice plane in a crystallite. High resolution TEM shows polysynthetic twinning in a number of crystals.
Hybrid Nanoscale Architecture for Enhancement of Antimicrobial Activity: Immobilization of Silver Nanoparticles on Thiol‐Functionalized Polymer Crystallized on Carbon Nanotubes
Authors: Misra R. Devesh K. , Girase Bhupendra , Depan Dilip , Shah Jinesh S.
Published: October 2011

We describe here the synthesis and antimicrobial activity of an innovative nanohybrid system, characterized by attachment of silver nanoparticles (AgNPs) to the thiol‐functionalized polymer that was periodically crystallized on carbon nanotubes (CNTs). The synthesis of the nanohybrid architecture first involved direct crystallization of thiol‐functionalized copolymer along the long axis of CNTs, followed by attachment of AgNPs to the thiol‐group of functionalized copolymer. The antimicrobial activity was assessed in terms of interaction withEscherichia coli, where the constituents of the nanohybrid structure play a synergistic role. The antimicrobial activity was approximately four orders of magnitude greater than the ex situ precipitated bare AgNPs. Possible mechanisms underlying enhanced antimicrobial activity are discussed. The study underscores the potential of uniquely combining CNTs and biopolymers for biomedical applications, in the present case, antimicrobial activity.
Liquid‐Crystalline Perylene Diester Polymers with Tunable Charge‐Carrier Mobility
Authors: Muth Mathis‐Andreas , Carrasco‐Orozco Miguel , Thelakkat Mukundan
Published: October 2011

New classes of liquid‐crystalline semiconductor polymers based on perylene diester benzimidazole and perylene diester imide mesogens are reported. Two highly soluble side‐chain polymers, poly(perylene diester benzimidazole acrylate) (PPDB) and poly(perylene diester imide acrylate) (PPDI) are synthesized by nitroxide‐mediated radical polymerization (NMRP). PPDB shows n‐type semiconductor performance with electron mobilities of 3.2 × 10−4 cm2 V−1 s−1 obtained in a diode configuration by fitting the space‐charge‐limited currents (SCLC) according to the Mott–Gurney equation. Interestingly, PPDI performs preferentially as a p‐type material with a hole mobility of 1.5 × 10−4 cm2 V−1 s−1, which is attributed to the less electron‐deficient perylene core of PPDI compared to PPDB. Optical properties are investigated by UV‐vis and fluorescence spectroscopy. The extended π‐conjugation system due to the benzimidazole unit of PPDB leads to a considerably broader absorption in the visible region compared to PPDI. HOMO and LUMO levels of the polymers are also determined by cyclic voltammetry; the resulting energy band‐gaps are 1.86 eV for PPDB and 2.16 eV for PPDI. Thermal behavior and liquid crystallinity are studied by differential scanning calorimetry, polarized optical microscopy, and X‐ray diffraction measurements. The results indicate liquid‐crystalline order of the polymers over a broad temperature range. These thermal, electrical, and optical properties make the perylene side‐chain polymers attractive materials for organic photovoltaics.
Development and Evaluation of Porous Materials for Carbon Dioxide Separation and Capture
Authors: Bae Youn‐Sang , Snurr Randall Q.
Published: October 2011

The development of new microporous materials for adsorption separation processes is a rapidly growing field because of potential applications such as carbon capture and sequestration (CCS) and purification of clean‐burning natural gas. In particular, new metal‐organic frameworks (MOFs) and other porous coordination polymers are being generated at a rapid and growing pace. Herein, we address the question of how this large number of materials can be quickly evaluated for their practical application in carbon dioxide separation processes. Five adsorbent evaluation criteria from the chemical engineering literature are described and used to assess over 40 MOFs for their potential in CO2 separation processes for natural gas purification, landfill gas separation, and capture of CO2 from power‐plant flue gas. Comparisons with other materials such as zeolites are made, and the relationships between MOF properties and CO2 separation potential are investigated from the large data set. In addition, strategies for tailoring and designing MOFs to enhance CO2 adsorption are briefly reviewed.
Synthesis of high performance polyamides utilizing copper‐catalyzed amidation of a dibromoarene with different diamides
Authors: Ghaemy Mousa , Nasr Farzaneh Hashemi
Published: October 2011

A series of diphenylquinoxaline‐containing polyamides were prepared from the condensation polymerization of 2,3‐bis (4‐bromophenyl) quinoxaline (DBQ) with various primary and secondary diamides via copper‐catalyzed amidation reaction. The polyamides were characterized with FTIR, NMR, GPC, differential scanning calorimeter, and thermo gravimetric analysis, and their solubility and viscosity were measured. The polyamides synthesized here are amorphous and showed relatively good solubility in polar aprotic solvents and demonstrate the ability to form brownish hard films by solvent casting; their inherent viscosities ranged from 49 to 55 mL/g. The average molecular weights of polyamides were in the range of Mw = 11,950–5592 g/mol (MWD = 1.21–1.87). These polyamides had relatively high thermal stability with Tg values up to 276°C, 10% weight loss temperatures (T10%) in the range of 364–476°C, and char yields at 600°C in N2 up to 72%. They also exhibit emission in the solid state and in dilute (0.2 g/dL) DMAc solution at 425–484 nm with photoluminescence quantum (ϕf) yields in the range of 14–23%. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Angle‐resolved light scattering from textured injection‐molded plastics
Authors: Ignell Sofie , Rigdahl Mikael
Published: October 2011

With regard to surface appearance, the angle‐resolved light scattering from textured polymeric surfaces was evaluated to link the reflectance properties to measured gloss as well as visually perceived gloss. Bidirectional reflectance distributions were determined by means of a scatterometer and the specimens involved were textured injection‐molded plaques manufactured from three different polymers; an acrylonitrile‐butadiene‐styrene (ABS) copolymer, a polypropylene (PP), and a polycarbonate and ABS copolymer blend (PC/ABS). The influence of color, surface roughness, and angle of incidence on the scattering characteristics was evaluated. An off‐specular reflectance peak was observed for the textured specimens the magnitude of which was clearly determined by the surface roughness and the angle of incidence. The color of the specimens mainly influenced the diffuse reflectance. The results provide a measure of perceived gloss and supported previously reported findings regarding the relevance of the concept of contrast gloss for the gloss characterization of textured polymeric surfaces. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Influence of clay content on the melting behavior and crystal structure of nonisothermal crystallized poly(L‐lactic acid)/nanocomposites
Authors: Ublekov F. , Baldrian J. , Kratochvil J. , Steinhart M. , Nedkov E.
Published: October 2011

To study the effect of organophilic clay concentration on nonisothermal crystallization, poly(L‐lactic acid) (PLLA)/montmorillonite (MMT) nanocomposites were prepared by mixing various amounts of commercial MMT (Cloisite® 30B) and PLLA. The effect of MMT content on melting behavior and crystal structure of nonisothermal crystallized PLLA/MMT nanocomposites was investigated by differential scanning calorimetry (DSC), small‐angle X‐ray scattering, and wide‐angle X‐ray diffraction (XRD) analyses. The study was focused on the effect of the filler concentration on thermal and structural properties of the nonisothermally crystallized nanocomposite PLLA/MMT. The results obtained have shown that at filler loadings higher than 3 wt %, intercalation of the clay is observed. At lower clay concentrations (1–3 wt %), exfoliation predominates. DSC and XRD analysis data show that the crystallinity of PLLA/MMT composites increases drastically at high clay loadings (5–9 wt %). In these nanocomposites, PLLA crystallizes nonisothermally in an orthorhombic crystal structure, assigned to the α form of PLLA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Effect of pellet size and compatibilization on thermal decomposition kinetic of recycled polyethylene terephthalate/recycled polypropylene blend
Authors: Thumsorn Supaphorn , Yamada Kazushi , Wei Leong Yew , Hamada Hiroyuki
Published: October 2011

This study considers the effects of pellet geometry and compatibilization on its moisture absorption and thermal degradation behavior of recycled polyethylene terephthalate (RPET) and recycled polypropylene (RPP) blend with the ultimate goal of optimizing the design of pellets to enhance their processability. The isoconversion of Flynn–Wall–Ozawa (FWO) was used for the kinetic study, which was suitable for thermal degradation of RPET/RPP blend in N2 while the second order polynomial function was fitted for thermal oxidative degradation in air. Finer geometries, such as powders, were found to have higher moisture absorption rates due to their large surface area although they could also be easily dried. Furthermore, large surface area of fine powder as well as good interaction between RPP disperse particles and RPET matrix eased to decompose in the presence of oxygen thus accelerated chain breaking during thermal oxidative degradation especially at low heating rate. Meanwhile, larger pellets exhibited higher degradation activation energies, which suggest that they are more resistant to thermal degradation than smaller grains. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Weathering of low‐density polyethylene grafted with itaconic acid in laboratory tests
Authors: Wojtala Anna , Czaja Krystyna , Sudoł Marek , Semeniuk Izabela
Published: October 2011

Polyethylene grafted with itaconic acid was subjected to weathering under laboratory accelerated conditions. The course of the photo‐oxidative degradation process of that material was studied by FTIR spectroscopy both through quantitative measurements of changes in absorbance values at selected wave numbers and through measurements of surface area values for absorption bands which were separated by means of deconvolution. The use of both those procedures of quantitative determinations resulted in a general conclusion that the oxidation process was initiated from the very first moment of irradiation, and it produced ketones, acids, esters (intramolecular and of acetate type), peracids, peresters, hydroperoxides, and alcohols. The molecular weight values and gel number values, which were established as well, pointed out that oxidation was accompanied by cracking of polymer macromolecules, and also by polymer crosslinking to a limited degree. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Effect of molecular weight of an anionic dispersant on the properties of BaTi4O9 slurries
Authors: Chung Tzu‐Min , Hsu Kung‐Chung
Published: October 2011

The colloidal stability of BaTi4O9 (BT4) aqueous suspensions with poly(acrylamide‐co‐4‐carboxylamino‐4‐oxo‐2‐butenate) (PAC) of different molecular weights at pH 9 has been investigated by means of zeta potential, adsorption, sedimentation, and particle size measurements. The results indicate that PAC could improve the dispersion of the particles from agglomeration. The resulting suspensions became more stabilized, and contained powder with smaller particle size. Consequently, the compacts with PAC exhibited better properties in terms of density and dielectric constant than those without any polymer present. The performance of PAC increased with decreasing polymer molecular weight. Clearly, PAC1 (Mw = 1.8 × 104) was most effective in dispersing the BT4 particles, and stabilizing the ceramic suspensions. This is attributed to the highest adsorption of this polymer onto BT4 powder, and causes strongest electrostatic repulsions among solid particles. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Synthesis and characterization of novel polyimides containing triazoles units in the main chain by click chemistry
Authors: Hajipour Abdol R. , Abrishami Fatemeh
Published: October 2011

In this study, some polyimides containing triazoles units in the main chain was prepared from the polymerization of dialkynes including imide linkages and diazides in the presence of Cu (I) catalyst in yield of 76.2–87.6%, with inherent viscosity of 0.37–0.53 dL g−1. The obtained polymers are soluble in polar aprotic solvents such as N,N‐dimethyformamide (DMF), N,N‐dimethyacetamide (DMAc), dimethyl sulfoxide (DMSO), and N‐methyl‐2‐pyrrolidone (NMP). These polymers were characterized using FT‐IR, 1H‐NMR, and elemental analysis techniques. Their thermal stability was evaluated with thermogravimetric (TGA) analysis and differential scanning calorimetry (DSC) techniques under a nitrogen atmosphere which is indicative of their good thermal stability. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Effects of poly(1,2‐propylene glycol adipate) and nano‐CaCO3 on DOP migration and mechanical properties of flexible PVC
Authors: Li Xihong , Xiao Yao , Wang Biao , Tang Yao , Lu Yaqing , Wang Chengjun
Published: October 2011

Nano‐CaCO3 was used as nano‐scale filler and poly(1,2‐propylene glycol adipate) (PPA) was used as polymeric plasticizer in flexible poly(vinyl chloride) (PVC) sheets for the partial replacement of di(2‐ethyl hexyl) phthalate (DOP) in this paper. The effect of PPA and nano‐CaCO3 on restraining DOP migration was evaluated via extraction tests. The results showed that the introduction of nano‐CaCO3 can decrease the extraction rate of DOP in the PVC matrix. The tensile strength and elongation at break of CaCO3‐1/PPA‐20/DOP‐30/PVC were similar to those of DOP‐50/PVC, and CaCO3‐1/PPA‐20/DOP‐30/PVC exhibited the superior suppression of DOP migration compared with DOP‐50/PVC. Thermogravimetry analysis (TGA) indicated that the addition of nano‐CaCO3 effectively improved the thermal stability of the nanocomposites. Therefore, the combination of PPA and nano‐CaCO3 is an effective approach to suppress the migration of DOP. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Characterization of soybean protein concentrate—stearic acid/palmitic acid blend edible films
Authors: de la Caba K. , Peña C. , Ciannamea E. M. , Stefani P. M. , Mondragon I. , Ruseckaite R. A.
Published: October 2011

The effect of incorporating commercial stearic acid/palmitic acid blend (SA/PA, 63/37 wt %) into hydrophilic soybean protein concentrate (SPC) film‐forming solutions at neutral and alkaline pH on some selected properties of edible cast films was investigated. SA/PA‐added SPC film exhibited a significant increase in translucency, being more relevant for films obtained at pH 7. This was associated with the more heterogeneous morphology of such films as observed by scanning electron microscopy. Calorimetric measurements and X‐ray diffraction studies confirmed the presence of crystalline fatty acids in films at pH 7 and new crystalline structures at pH 10 due to interactions or reactions between SPC and SA/PA blend. Fourier Transform infrared spectroscopy results confirmed the incorporation of fatty acids into SPC and revealed the occurrence of interactions between both components, depending on the film‐forming emulsion pH. Moisture absorption isotherms at high relative humidity (RH) were determined and experimental data were adequately fitted by Peleg's empirical equation. Control SPC films produced at pH 7 were distinctly more moisture resistant than those at pH 10 owing to the more charged protein molecules at alkaline pH. The increased moisture resistance of SA/PA‐added‐SPC film at pH 10 was related to the more homogeneous dispersion of fatty acid particles within the protein matrix. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Chemical synthesis, characterization, and properties of conducting copolymers of imidazole and pyridine
Authors: Raj V. , Madheswari D. , Mubarak Ali M.
Published: October 2011

A series of conducting copolymers were synthesized by chemical oxidative polymerization of imidazole (Imi) and pyridine (Py) in acetonitrile medium at ambient temperature. The yield, solubility, and conductivity of the copolymers were measured by changing the Imi/Py molar ratio from 0/100 to 100/0. The as‐prepared Imi/Py conducting copolymers were characterized by UV‐Visible, FTIR, 1H‐NMR, DSC, TGA, and XRD. The results suggest that the resulting copolymers were more easily soluble in most of the organic solvents than in polyimidazole. The polymer obtained is a real copolymer containing imidazole and pyridine units, but the Imi content calculated on the basis of the proton NMR spectra is lower than feed Imi content. The thermostability of the Imi/Py copolymer increases with increasing Imi unit content. The copolymers show comparatively higher conductivity and higher thermal stability than the homopolymer polypyridine and are lower than those of polyimidazole. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Temperature and time dependence of electrical resistivity in an anisotropically conductive polymer composite with in situ conductive microfibrils
Authors: Zhang Yi‐Chuan , Dai Kun , Pang Huan , Luo Qiao‐Ji , Li Zhong‐Ming , Zhang Wei‐Qin
Published: October 2011

An anisotropically conductive polymer composite (ACPC) based on conductive carbon black (CB) and binary polymer blend of polyethylene (PE) and polyethylene terephthalate (PET) was successfully fabricated under shear and elongational flow fields. The PET phase formed in situ the aligned conductive microfibrils whose surfaces were coated by CB particles. This ACPC material exhibited a strong electrical anisotropy within a broad temperature range. When the ACPC samples were subjected to isothermal treatment (IT), they showed anomalous variations of the positive temperature coefficient (PTC) and negative temperature coefficient (NTC) effects. The PTC intensity was attenuated gradually with the increase of the IT time, and the NTC intensity was nearly eliminated after IT of 8 or 16 h. Beyond 16 h, the resistivity in the NTC region rose anomalously with the temperature after the elimination of NTC effect, which was the result of much transformation from the potential pathways to the intrinsic pathways due to the disordering of oriented conductive microfibrils. When the amount of potential pathways was very small, the effect of the intrinsic pathway separation surmounts that of the potential pathways, leading to the anomalous resistivity increase in the NTC region. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Selective sorption of Fe(III) using modified forms of chitosan beads
Authors: Gandhi Muniyappan Rajiv , Kousalya G. N. , Meenakshi S.
Published: October 2011

Modified chitosan beads (CB) were prepared and used for the removal of Fe(III) ions from aqueous solution. The advantages of modified CB than raw CB have been explored. The sorption capacity (SC) of the modified forms of CB namely, protonated CB, carboxylated CB, and grafted CB were found to be 3533, 3905, and 4203 mg kg−1, respectively, while the raw CB showed the SC of 2913 mg kg−1 only. Batch adsorption studies were conducted to optimize various equilibrating conditions like contact time, pH, and coions. The sorbents were characterized by FTIR, WDXRF, and SEM with EDAX analysis. The sorption process has been explained with Freundlich and Langmuir isotherms. Thermodynamic parameters such as ΔG°, ΔH°, and ΔS° were calculated to understand the nature of sorption. Modified CB are more selective for Fe(III) than Cu(II), which inturn higher than Cr(VI). A suitable mechanism for iron sorption onto modified CB was established. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
The effect of synthesis condition on physical properties of epoxy‐containing microcapsules
Authors: Wang Rongguo , Hu Honglin , Liu Wenbo , He Xiaodong , Guo Qiong
Published: October 2011

The physical properties of microcapsules are largely influenced by the synthesis conditions such as weight ratio of core/shell material, agitation rate, reaction time, and different emulsifier. Different synthesis condition would lead to different property. It is an important issue for application in composites that require self‐healing microcapsules possessing rough surface morphology, less adhesion, less core material permeability, appropriate diameter and core content, and adequate shell thickness. The properties of microcapsules influenced by the synthesis conditions were investigated systematically in this article. According to orthographic factorial design, the most influencing factor on microcapsule's yield, core material, average shell thickness and average diameter, are concluded, respectively. The synthesis parameters when the epoxy‐containing microcapsules exhibit the optimum properties are concluded: 1.4 : 1 for the weight ratio of core/shell material, 250 rpm for the agitation rate, 3 h for the reaction time and 1.5% content for the emulsifier DBS. The chemical structure of resultant microcapsules is confirmed by FT‐IR, and core material of microcapsule exhibits reactivity through DSC measurement. Subsequently, the microcapsules are characterized by SEM, OM, and contact angle experiment so as to provide parameters of microcapsule's physical properties for making binary self‐healing materials. As a result, the resultant microcapsules are suitable for fabricating self‐healing materials. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Effects of graphene nanosheets on the dielectric, mechanical, thermal properties, and rheological behaviors of poly(arylene ether nitriles)
Authors: Yang Xulin , Zhan Yingqing , Zhao Rui , Liu Xiaobo
Published: October 2011

Poly(arylene ether nitriles) (PEN) containing various contents of graphene nanosheets (GNs) was prepared via solution‐casting method and investigated for their dielectric, mechanical, thermal, and rheological properties. For PEN/GNs nanocomposite with 5 wt % GNs, the dielectric constant was increased to 9.0 compared with that of neat PEN (3.1) and dielectric losses of all nanocomposites were in the range of 0.019–0.023 at 1 kHz. The tensile modulus and strength were increased about 6 and 14% with 0.5% GNs, respectively. The fracture surfaces of the all PEN/GNs nanocomposites revealed that GNs had good adhesion to PEN matrix. The thermal properties of the nanocomposites showed significant increase with increasing GN loading. For 5 wt % GNs‐reinforced PEN nanocomposite, the temperatures corresponding to a weight loss of 5 wt % (Td5%) and 30 wt % (Td30%) increased by about 20 and 13°C, respectively. Rheological properties of the PEN nanocomposites showed a sudden change with the GN fraction and the percolation threshold was about 1 wt % of GNs. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Dispersion of nanoparticles in poly(vinyl chloride) grains during In situ polymerization
Authors: Georgiadou Stella , Jin Lili , Thomas Noreen. L. , Gilbert Marianne. , Brooks Brian W.
Published: October 2011

Inorganic nanoparticles such as calcium carbonate, silica, or hydrotalcite were dispersed in vinyl chloride prior to suspension polymerization. That led to the production of poly(vinyl chloride) (PVC) composite grains with higher porosity and different internal morphology from those of commercial PVC. The PVC/composite grain sizes and their distribution were also influenced by the presence of nanofillers. The distribution of filler nanoparticles (either calcium carbonate or silica) was not uniform throughout the PVC grains. Regions of high and low filler concentration were observed. Regions of pure polymer were also observed. Reasons for that are suggested. Hydrotalcite did not remain in the PVC grains. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Wood flour/polylactide biocomposites toughened with polyhydroxyalkanoates
Authors: Qiang Tao , Yu Demei , Gao Honghong
Published: October 2011

Polylactide (PLA)‐based wood–plastic composites (WPCs) were successfully manufactured by extrusion blending followed by injection molding. The effects of polyhydroxyanoates (PHAs) on the mechanical and thermal properties and the morphologies of the PLA‐based WPCs were investigated with mechanical testing, thermal analysis, and scanning electronic microscopy (SEM). The inclusion of PHAs in the PLA‐based WPCs produced an increase in the impact resistance and a decrease in the tensile strength. The brittle–ductile transition of the impact strength for the PLA‐based WPCs toughened with PHAs was confirmed when the wood flour content was between 15 and 35 wt %. SEM images showed that the fracture surfaces of the PLA‐based WPCs toughened with PHAs were rougher than that of their nontoughened counterparts. The ternary PLA‐based WPCs exhibited ductile fracture during mechanical testing. Differential scanning calorimetry (DSC) showed that addition of PHAs into the composites caused deviations of the cold crystallization temperature and melting temperature of PLA. Thermogravimetric analysis indicated that the PHAs reduced the thermal stability of the PLA‐based WPCs. PHAs can be a green toughening agent for PLA‐based WPCs. The specific properties evidenced by the biocomposites may hint at their potential application, for example, in the automotive industry and civil engineering. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Protective effect of cashew gum nanoparticles on natural larvicide from Moringa oleifera seeds
Authors: Paula Haroldo C. B. , Rodrigues Maria L. L. , Ribeiro Wesley L. C. , Stadler Andre S. , Paula Regina C. M. , Abreu Flavia O. M. S.
Published: October 2011

Nanoparticles (NPs) have been used as carriers and as protective coatings of labile substances with applications in pharmacy, medicine, and agriculture. This work focused on the development of an entrapment process for the protection of a natural larvicide extracted from Moringa oleifera (MO) seeds with cashew gum (CG) NPs as a wall material. CG–MO NPs were characterized with regard to their size, morphology, kinetic release, thermal properties, and Stegomya aegypti larvae mortality. The result showed that the CG–MO NPs presented average particle sizes ranging from 288 to 357 nm, with unimodal distribution. MO larvicide active principle loading varied from 2.6 to 4.4%, and the entrapment efficiencies were in the range 39.1–60.8%. In vitro release kinetics showed a Fickian diffusional behavior. The thermal stability of the CG–MO NPs was related to the MO content, where their decomposition temperatures decreased with increasing MO active principle loading. Bioassays with third instar larvae showed that the mortality rate was related to larvicide loading and reached values up to 98 ± 3% mortality. The CG–MO NPs showed effective extract entrapment, with satisfactory larvicide effects even after 55 days of sample preparation and were effective as an improved and controlled release larvicide system. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Systematic review of wireless phone use and brain cancer and other head tumors
Authors: Repacholi Michael H. , Lerchl Alexander , Röösli Martin , Sienkiewicz Zenon , Auvinen Anssi , Breckenkamp Jürgen , d'Inzeo Guglielmo , Elliott Paul , Frei Patrizia , Heinrich Sabine , Lagroye Isabelle , Lahkola Anna , McCormick David L. , Thomas Silke , Vecchia Paolo
Published: October 2011

We conducted a systematic review of scientific studies to evaluate whether the use of wireless phones is linked to an increased incidence of the brain cancer glioma or other tumors of the head (meningioma, acoustic neuroma, and parotid gland), originating in the areas of the head that most absorb radiofrequency (RF) energy from wireless phones. Epidemiology and in vivo studies were evaluated according to an agreed protocol; quality criteria were used to evaluate the studies for narrative synthesis but not for meta‐analyses or pooling of results. The epidemiology study results were heterogeneous, with sparse data on long‐term use (≥10 years). Meta‐analyses of the epidemiology studies showed no statistically significant increase in risk (defined as P < 0.05) for adult brain cancer or other head tumors from wireless phone use. Analyses of the in vivo oncogenicity, tumor promotion, and genotoxicity studies also showed no statistically significant relationship between exposure to RF fields and genotoxic damage to brain cells, or the incidence of brain cancers or other tumors of the head. Assessment of the review results using the Hill criteria did not support a causal relationship between wireless phone use and the incidence of adult cancers in the areas of the head that most absorb RF energy from the use of wireless phones. There are insufficient data to make any determinations about longer‐term use (≥10 years). Bioelectromagnetics 33:187–206, 2012. © 2011 Wiley Periodicals, Inc.
Effect of the definition of type II diabetes remission in the evaluation of bariatric surgery for metabolic disorders
Authors: Pournaras D J , Aasheim E T , Søvik T T , Andrews R , Mahon D , Welbourn R , Olbers T , le Roux C W
Published: October 2011

Background

The American Diabetes Association recently defined remission of type II diabetes as a return to normal measures of glucose metabolism (haemoglobin (Hb) A1c below 6 per cent, fasting glucose less than 5·6 mmol/l) at least 1 year after bariatric surgery without hypoglycaemic medication. A previously used common definition was: being off diabetes medication with normal fasting blood glucose level or HbA1c below 6 per cent. This study evaluated the proportion of patients achieving complete remission of type II diabetes following bariatric surgery according to these definitions.

Methods

This was a retrospective review of data collected prospectively in three bariatric centres on patients undergoing gastric bypass, sleeve gastrectomy and gastric banding.

Results

Some 1006 patients underwent surgery, of whom 209 had type II diabetes. Median follow-up was 23 (range 12–75) months. HbA1c was reduced after operation in all three surgical groups (P < 0·001). A total of 72 (34·4 per cent) of 209 patients had complete remission of diabetes, according to the new definition; the remission rates were 40·6 per cent (65 of 160) after gastric bypass, 26 per cent (5 of 19) after sleeve gastrectomy and 7 per cent (2 of 30) after gastric banding (P < 0·001 between groups). The remission rate for gastric bypass was significantly lower with the new definition than with the previously used definition (40·6 versus 57·5 per cent; P = 0·003).

Conclusion

Expectations of patients and clinicians may have to be adjusted as regards remission of type II diabetes after bariatric surgery. Focusing on improved glycaemic control rather than remission may better reflect the benefit of this type of surgery and facilitate improved glycaemic control after surgery. Copyright © 2011 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd.
Research Protections for Diverted Mentally Ill Individuals: Should they be Considered Prisoners?
Authors: Amory Carr W. , Amrhein Charles , Dery Ryna
Published: October 2011

The number of diversion programs for the mentally ill has increased dramatically over the past decade. These programs serve the valuable goal of reducing the growing population of incarcerated mentally ill persons by providing supervised community treatment. Research within these programs, critical for improving outcomes for these vulnerable individuals, is complicated by the fact that participants may have legal statuses which carry significant coercive leverage. In this way their ability to freely consent to research may be limited. In this paper, the authors describe the practice of diversion and review relevant research on coercion, informed consent and decisional capacity among the mentally ill and imprisoned. Current legal protections for prisoners are then discussed in the light of a recent proposal to broaden the legal definition of “prisoner” for research purposes to include community corrections populations, thus including diverted individuals. Copyright © 2011 John Wiley & Sons, Ltd.
Mechanistic Basis for RNA Aptamer‐Based Induction of TetR
Authors: Steber Markus , Arora Amit , Hofmann Jan , Brutschy Bernhard , Suess Beatrix
Published: October 2011

The TetR aptamer induces TetR controlled gene expression, and represents an interesting tool for application in synthetic biology. We have analysed the mechanistic basis for RNA aptamer‐based induction of TetR. The aptamer binds TetR with a high affinity in the order of 107 M−1, which is similar to operator DNA binding under the used ionic conditions. We identified the binding epitope of the aptamer on TetR, which consists of amino acids T27, N47 and K48 of both monomers, using loss‐of‐function analysis and electrophoretic mobility shift assays. Tetracycline‐induced conformational changes of TetR led to reorientation of the DNA reading head. This movement destroys the composite binding epitope for the aptamer and leads to reduced RNA binding by one order of magnitude. The aptamer can actively displace TetR from the operator DNA; this could be the key factor for its activity in vivo.
Shaping microtubules into diverse patterns: Molecular connections for setting up both ends
Authors: Mimori‐Kiyosue Yuko
Published: October 2011

Microtubules serve as rails for intracellular trafficking and their appropriate organization is critical for the generation of cell polarity, which is a foundation of cell differentiation, tissue morphogenesis, ontogenesis and the maintenance of homeostasis. The microtubule array is not just a static railway network; it undergoes repeated collapse and reassembly in diverse patterns during cell morphogenesis. In the last decade much progress has been made toward understanding the molecular mechanisms governing complex microtubule patterning. This review first revisits the basic principle of microtubule dynamics, and then provides an overview of how microtubules are arranged in highly shaped and functional patterns in cells changing their morphology by factors controlling the fate of microtubule ends. © 2011 Wiley Periodicals, Inc.
Myotilin dynamics in cardiac and skeletal muscle cells
Authors: Wang Jushuo , Dube Dipak K. , Mittal Balraj , Sanger Jean M. , Sanger Joseph W.
Published: October 2011

Myotilin cDNA has been cloned for the first time from chicken muscles and sequenced. Ectopically expressed chicken and human YFP‐myotilin fusion proteins localized in avian muscle cells in the Z‐bodies of premyofibrils and the Z‐bands of mature myofibrils. Fluorescence recovery after photobleaching experiments demonstrated that chicken and human myotilin were equally dynamic with 100% mobile fraction in premyofibrils and Z‐bands of mature myofibrils. Seven myotilin mutants cDNAs (S55F, S55I, T57I, S60C, S60F, S95I, R405K) with known muscular dystrophy association localized in mature myofibrils in the same way as normal myotilin without affecting the formation and maintenance of myofibrils. N‐ and C‐terminal halves of human myotilin were cloned and expressed as YFP fusions in myotubes and cardiomyocytes. N‐terminal myotilin (aa 1–250) localized weakly in Z‐bands with a high level of unincorporated protein and no adverse effect on myofibril structure. C‐terminal myotilin (aa 251–498) localized in Z‐bands and in aggregates. Formation of aggregated C‐terminal myotilin was accompanied by the loss of Z‐band localization of C‐terminal myotilin and partial or complete loss of alpha‐actinin from the Z‐bands. In regions of myotubes with high concentrations of myotilin aggregates there were no alpha‐actinin positive Z‐bands or organized F‐actin. The dynamics of the C‐terminal‐myotilin and N‐terminal myotilin fragments differed significantly from each other and from full‐length myotilin. In contrast, no significant changes in dynamics were detected after expression in myotubes of myotilin mutants with single amino acid changes known to be associated with myopathies. © 2011 Wiley Periodicals, Inc.
Substructure‐Based Virtual Screening for Adenosine A2A Receptor Ligands
Authors: van der Horst Eelke , van der Pijl Rianne , Mulder‐Krieger Thea , Bender Andreas , IJzerman Adriaan P.
Published: October 2011

A virtual ligand‐based screening approach was designed and evaluated for the discovery of new A2A adenosine receptor (AR) ligands. For comparison and evaluation, the procedures from a recently published virtual screening study that used the A2A AR X‐ray crystal structure for the target‐based discovery of new A2A ligands were largely followed. Several screening models were constructed by deriving the distinguishing structural features from selected sets of A2A AR antagonists, so‐called frequent substructure mining. The best model in statistical terms was subsequently applied to large‐scale virtual screens of a commercial vendor library. This resulted in the selection of 36 candidates for acquisition and testing. Of the selected candidates, eight compounds significantly inhibited radioligand binding at A2A AR (>30 %) at 10 μM, corresponding to a “hit rate” of 22 %. This hit rate is quite similar to that of the referenced target‐based virtual screening study, while both approaches yield new, non‐overlapping sets of ligands.
Prognostic significance of alterations in IDH enzyme isoforms in patients with AML treated with high‐dose cytarabine and idarubicin
Authors: Ravandi Farhad , Patel Keyur , Luthra Rajyalakshmi , Faderl Stefan , Konopleva Marina , Kadia Tapan , Brandt Mark , Pierce Sherry , Kornblau Steven , Andreeff Michael , Wang Xuemei , Garcia‐Manero Guillermo , Cortes Jorge , Kantarjian Hagop
Published: October 2011

BACKGROUND:

IDH1 and IDH2 gene mutations are novel, recurring molecular aberrations among patients with normal karyotype acute myeloid leukemia (AML).

METHODS:

Among 358 patients with AML treated on 4 protocols using high‐dose ara‐C plus idarubicin induction, pretreatment samples were available for 170 (median age 53 years, [range, 17‐73]; 96% ≤65) and were evaluated for IDH1R132, IDH2R172, and IDH2R140 mutations or the codon 105 single nucleotide polymorphism (SNP) in IDH1.

RESULTS:

IDH1 and IDH2 mutations were present in 12 (7%) and 24 (14%) of patients, and IDH1 G105 SNP in 24 (14%). Overall, 52 (30%) patients had IDH gene alterations. There was no association with complete response (CR), remission duration, overall survival, and event‐free survival and any of the IDH alterations, and no association with a higher CR rate or survival with the 4 regimens for the 52 patients with aberrant IDH. Among the patients with diploid karyotype and NPM1mutFLT3WTgenotype, those with IDH1 or IDH2 mutations had an inferior outcome.

CONCLUSIONS:

IDH aberrations and IDH1 codon 105 SNP occur in about 30% of younger patients with AML, mostly with diploid karyotype. Using high‐dose ara‐C‐based induction regimens, we did not detect an association with outcome for any of the aberrations. Cancer 2011;. © 2011 American Cancer Society.
Development and distribution of neuronal cilia in mouse neocortex
Authors: Arellano Jon I. , Guadiana Sarah M. , Breunig Joshua J. , Rakic Pasko , Sarkisian Matthew R.
Published: October 2011

Neuronal primary cilia are not generally recognized, but they are considered to extend from most, if not all, neurons in the neocortex. However, when and how cilia develop in neurons are not known. This study used immunohistochemistry for adenylyl cyclase III (ACIII), a marker of primary cilia, and electron microscopic analysis to describe the development and maturation of cilia in mouse neocortical neurons. Our results indicate that ciliogenesis is initiated in late fetal stages after neuroblast migration, when the mother centriole docks with the plasma membrane, becomes a basal body, and grows a cilia bud that we call a procilium. This procilium consists of a membranous protrusion extending from the basal body but lacking axonemal structure and remains undifferentiated until development of the axoneme and cilia elongation starts at about postnatal day 4. Neuronal cilia elongation and final cilia length depend on layer position, and the process extends for a long time, lasting 8–12 weeks. We show that, in addition to pyramidal neurons, inhibitory interneurons also grow cilia of comparable length, suggesting that cilia are indeed present in all neocortical neuron subtypes. Furthermore, the study of mice with defective ciliogenesis suggested that failed elongation of cilia is not essential for proper neuronal migration and laminar organization or establishment of neuronal polarity. Thus, the function of this organelle in neocortical neurons remains elusive. J. Comp. Neurol., 2012. © 2011 Wiley Periodicals, Inc.
Designing Magnetic Organic Lattices from High‐Spin Polycyclic Units
Authors: Trinquier Georges , Suaud Nicolas , Guihéry Nathalie , Malrieu Jean‐Paul
Published: October 2011

This work addresses the conception of purely organic magnetic materials by properly bridging high‐spin polycyclic hydrocarbons A and B, through covalent ligands L. The strategy varies two degrees of freedom that govern the magnetic character of the A–L‐‐B sequence, namely, the bridge response to spin polarization and the relative signs of spin density on carbon atoms to which the bridge is attached. Topological prescriptions based on Ovchinnikov’s rule are proposed to predict ground‐state spin multiplicities of various A–L–B sets. The relevance of these guiding principles is essentially confirmed through DFT calculations on dimers connected by conjugated bridges. The transferability of interunit magnetic couplings to larger assemblies is further checked, the building blocks tending to maintain their high‐spin character whatever the environment. Such local designs open the way to periodic lattices of ferromagnetic, antiferromagnetic, ferrimagnetic, or paramagnetic materials.
Electromagnetically driven two‐axis optical beam steering MEMS mirror and its dependence of actuation on magnetic field
Authors: Watanabe Yoshiyuki , Abe Yutaka , Iwamatsu Shinnosuke , Kobayashi Seiya , Takahashi Yoshiyuki , Sato Toshiyuki
Published: October 2011

This paper describes the development of an electromagnetically driven two‐axis MEMS mirror which steers an optical beam, and the dependence of the tilting angles on the magnet shape and size and the initial gap between planar coils and the magnet surface. A reflective Au mirror (1.8 × 1.8 mm2) can be tilted bidirectionally with an electromagnetic force induced by the current of the planar coils and the magnetic field of a permanent magnet. A newly developed MEMS mirror device (10 × 10 × 0.2 mm3) was set on a printed circuit board (15 × 15 × 1.0 mm3), and the board was fixed on a holder in which a magnet was inset. The utilized magnets were cubic (6, 8, and 15 mm square and 5 mm thick), cylindrical (6 and 8 mm in diameter and 5 mm thick), and spherical (8 mm in diameter) to investigate efficient actuation. The initial gaps of the planar coils and magnet surface were 0, 500, 1000, and 2000 μm. The magnetic flux density and its gradient decreased with distance from the magnet surface. The tilting angles of the MEMS mirror increased with decreasing size of the square magnet and shorter distance, and were largest when using a magnet 6 mm square and a 500‐μm gap, in which condition the maximum tilting angles in the X and Y directions were 2.95 and 3.68 deg/mA, respectively. In addition, we obtained 3D‐OCT images of human finger tissue by using a Fourier domain fiber interferometer with a newly developed MEMS mirror. © 2011 Wiley Periodicals, Inc. Electron Comm Jpn, 94(11): 24–31, 2011; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.10377
Cyano‐ and Aqua‐Coordinated Diruthenium(III) Complexes with Oxo‐Bis(acetato) Bridge: Preparation and Steric and Electronic Structures
Authors: Zhang Hua‐Xin , Tsuge Kiyoshi , Sasaki Yoichi , Osawa Masatoshi , Abe Masaaki
Published: October 2011

Three new μ‐oxo‐bis(μ‐acetato)diruthenium(III) complexes,trans(μ‐O,OH2)‐[Ru2(μ‐O)(μ‐CH3COO)2(bpy)2(H2O)2][PF6]2·3H2O ([1][PF6]2·3H2O; bpy = 2,2′‐bipyridine), trans(μ‐O,CN)‐[{Ru2(μ‐O)(μ‐CH3COO)2(bpy)2}2{μ‐Ag(CN)2}{μ‐Ag2(CN)3}][Ag(CN)2][Ag2(CN)3](CH3CN)4(CH2Cl2) (2), and cis(μ‐O,CN)‐[Ru2(μ‐O)(μ‐CH3COO)2(bpy)2(CN)2]·CH3OH·H2O([3]·CH3OH·H2O), have been prepared and their X‐ray crystal structures determined. Whereas [1]2+ and 3 are discrete species, 2 is a polymer in which the Ag–CN groups act as bridges through Ru–CN(or NC)–Ag linkages. The discrete complexes dissolve in common solvents, but 2 is only slightly soluble in acetonitrile and dimethyl formamide (DMF) to give fragmented species (denoted as 2′) in solution. Redox waves of 3 were observed at –0.83 (Epc) and +0.76 V (E1/2) versus Ag/AgCl in a solution of 0.1 M nBu4NPF6 in CH2Cl2, which correspond to the Ru2II,III/Ru2III,III and Ru2III,III/Ru2III,IV processes, respectively. The corresponding redox couples (E1/2) of [1]2+ were observed at –0.31 and +0.76 V in 0.1 M NaClO4 aqueous solution. Significantly more negative potentials of the Ru2II,III/Ru2III,III couple for the two cyano complexes (E1/2 = –0.77 V for 2′) are noted. Complexes [1]2+, 2′, and 3 exhibit strong visible absorption bands at λmax = 566 nm (ϵ = 12600 M–1 cm–1; in H2O), 636 nm (21000 M–1 cm–1; in acetonitrile), and 558 nm (18000 M–1 cm–1; in H2O), respectively. Density functional theory (DFT) molecular orbital calculations have been carried out for [1]2+, trans(μ‐O,CN)‐[Ru2(μ‐O)(μ‐CH3COO)2(bpy)2(CN)2] (2a, a model compound for 2′), 3, [Ru2(μ‐O)(μ‐CH3COO)2(py)6]2+ ([4]2+), and trans(μ‐O,py)‐[Ru2(μ‐O)(μ‐CH3COO)2(bpy)2(py)2]2+ ([5]2+; py = pyridine). It was revealed that the frontier orbitals of these complexes are dominated by the Ru(dπ)–μ‐O(pπ) type π systems. For the cyano complexes, energies of these π‐type MOs are lifted up by the interaction with CN–, so that the energy difference with the upper bpy π* orbitals becomes smaller. Thus, whereas the visible absorption bands of [1]2+, [4]2+, and [5]2+ are ascribed to the transitions within the π system metal‐to‐metal charge transfer (MMCT), those of 2′ and 3 are ascribed to the HOMO‐to‐ligand π* (bpy) transition metal‐to‐ligand charge transfer (MLCT) and to the mixture of MMCT and MLCT (HOMO–1 to π*), respectively.