bluuebunny/crossref_metadata_2025 huggingface dataset:
A 1.4‐Gbps intra‐panel interface with low‐power and low‐EMI schemes for Tablet PC applications
Authors: Lee Dongmyung , Lee Kil‐Hoon , Baek Dong Hoon , Pae Hansu , Lim Jung‐Pil , Choi Young Min , Lee Young Hun , Lee Sun Ik , Lee Jae‐Youl , Nah Kyung‐Suc , Hwang Gyoocheol
Published: February 2013

An intra‐panel interface addressing all of the high‐speed, low‐power, and low‐electromagnetic interference (EMI) requirements for tablet personal computer applications is presented. This work proposes an adaptive clock window scheme to achieve 1.4‐Gbps data‐rate. For EMI suppression, data scrambling, horizontal blank period pattern scrambling, and novel clock and data recovery circuit are introduced. Lastly, for power‐saving, the proposed interface dynamically biases source driver's output buffers and employs early charge sharing by controlling the configuration data. For verification, a WQXGA thin‐film transistor liquid crystal display system is implemented with the timing controller and source driver ICs that are fabricated using 65‐nm and 180‐nm complementary metal‐oxide semiconductor (CMOS) processes, respectively. The liquid crystal display system demonstrates maximum operation speed of 1.4 Gbps and suppression of EMI noise in LTE Band‐20 and GSM 850 bands. The proposed power‐saving schemes achieve 4.3% reduction in total power consumption by source driver IC, which reaches about 85% of power consumption by enhanced reduced‐voltage differential signaling interface circuit.
Mild Oxidation of Thiofunctional Polymers to Cytocompatible and Stimuli‐Sensitive Hydrogels and Nanogels
Authors: Singh Smriti , Zilkowski Ilona , Ewald Andrea , Maurell‐Lopez Tobias , Albrecht Krystyna , Möller Martin , Groll Jürgen
Published: February 2013

Nanogels consist of three dimensionally cross‐linked hydrophilic polymer chains and can thus be easily modified through functionalization of the polymeric building blocks, for example to yield stimuli‐sensitive materials. For drug transport and intracellular release, redox‐sensitive systems are especially of interest, as the intracellular space is reductive. In this study, parameters that allow preparation of nanogels with tunable size between 150 and 350 nm are systematically evaluated and identified. Most importantly, a new and mild oxidation catalyst, alloxan, is introduced for the preparation of the nanogels. This broadens the range of possible payloads to more‐sensitive molecules. Particle stability, degradation in cytosolic conditions, and cytocompatibility in concentrations up to 10 mg · mL−1 are demonstrated.

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Burkholderia cenocepacia conditional growth mutant library created by random promoter replacement of essential genes
Authors: Bloodworth Ruhi A. M. , Gislason April S. , Cardona Silvia T.
Published: February 2013

Identification of essential genes by construction of conditional knockouts with inducible promoters allows the identification of essential genes and creation of conditional growth (CG) mutants that are then available as genetic tools for further studies. We used large‐scale transposon delivery of the rhamnose‐inducible promoter, PrhaB followed by robotic screening of rhamnose‐dependent growth to construct a genomic library of 106 Burkholderia cenocepacia CG mutants. Transposon insertions were found where PrhaB was in the same orientation of widely conserved, well‐characterized essential genes as well as genes with no previous records of essentiality in other microorganisms. Using previously reported global gene‐expression analyses, we demonstrate that PrhaB can achieve the wide dynamic range of expression levels required for essential genes when the promoter is delivered randomly and mutants with rhamnose‐dependent growth are selected. We also show specific detection of the target of an antibiotic, novobiocin, by enhanced sensitivity of the corresponding CG mutant (PrhaB controlling gyrB expression) within the library. Modulation of gene expression to achieve 30–60% of wild‐type growth created conditions for specific hypersensitivity demonstrating the value of the CG mutant library for chemogenomic experiments. In summary, CG mutants can be obtained on a large scale by random delivery of a tightly regulated inducible promoter into the bacterial chromosome followed by a simple screening for the CG phenotype, without previous information on gene essentiality.
Cell Therapy for Parkinson's Disease: What Next?
Authors: Bjorklund Anders , Kordower Jeffrey H.
Published: February 2013

The idea to use transplants of dopamine‐producing cells to substitute for the lost midbrain dopamine neurons in Parkinson's disease (PD) goes back to the 1970s. In this review we give an overview of the history of cell transplantation in animal models of PD, and summarize the experience gained from the open‐label and placebo‐controlled clinical trials performed so far using intrastriatal transplants of human fetal dopamine neuroblasts. Further development of this therapeutic approach face numerous challenges, for example in the development of protocols that allow generation of fully functional and safe midbrain dopamine neurons from stem cells. Based on recent promising advancements, efforts are now being made to develop standardized and efficient protocols, and adapt these protocols to good laboratory practice (GLP)/good manufacturing practice (GMP) conditions, to move this technology closer to clinical translation. © 2013 Movement Disorder Society
The structure of azines derived from C‐formyl‐1H‐imidazoles in solution and in the solid state: tautomerism, configurational and conformational studies
Authors: Pinto Joana , Silva Vera L. M. , Silva Artur M. S. , Claramunt Rosa M. , Sanz Dionisia , Torralba M. Carmen , Torres M. Rosario , Reviriego Felipe , Alkorta Ibon , Elguero José
Published: February 2013

The structures of three azines derived from 2‐formylimidazole, 4(5)‐formylimidazole, and 4(5)‐formyl‐5(4)‐methylimidazole have been determined in solution and in the solid state. Density Functional Theory (DFT) Polarizable Continuum Model (PCM) calculations (geometries, energies, and chemical shifts), NMR [solution and cross polarization magic‐angle spinning (CPMAS)], and X‐ray crystallography [azine of 4(5)‐formylimidazole] have been used. The configuration around the central C = N bonds has been determined and some insights about prototropic tautomerism and conformation have been gained. Copyright © 2013 John Wiley & Sons, Ltd.
Compartmentalization Effects on Miniemulsion Polymerization with Oil‐Soluble Initiator
Authors: Costa Cristiane , Timmermann Suzi A. S. , Pinto Jose Carlos , Araujo Pedro H. H. , Sayer Claudia
Published: February 2013

A dynamic mathematical model is developed to represent miniemulsion polymerization reactions using oil‐soluble initiator. Both simulation and experimental results show that the evolution of conversion varies with particle diameter and that reactions become slower as the particle size is increased. For each experimental condition, a limiting diameter is obtained, above which the reaction kinetics does not change anymore with the diameter. These results are explained in terms of the compartmentalization of growing radicals during the miniemulsion polymerizations. The evolution of conversion in bulk polymerizations shows that the kinetic behavior above the limiting diameter is similar to the kinetic behavior of bulk reactions.

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MRI analysis of cerebellar and vestibular developmental phenotypes in Gbx2 conditional knockout mice
Authors: Szulc Kamila U. , Nieman Brian J. , Houston Edward J. , Bartelle Benjamin B. , Lerch Jason P. , Joyner Alexandra L. , Turnbull Daniel H.
Published: February 2013

Purpose

Our aim in this study was to apply three‐dimensional MRI methods to analyze early postnatal morphological phenotypes in a Gbx2 conditional knockout (Gbx2‐CKO) mouse that has variable midline deletions in the central cerebellum, reminiscent of many human cerebellar hypoplasia syndromes.

Methods

In vivo three‐dimensional manganese‐enhanced MRI at 100‐µm isotropic resolution was used to visualize mouse brains between postnatal days 3 and 11, when cerebellum morphology undergoes dramatic changes. Deformation‐based morphometry and volumetric analysis of manganese‐enhanced MRI images were used to, respectively, detect and quantify morphological phenotypes in Gbx2‐CKO mice. Ex vivo micro‐MRI was performed after perfusion‐fixation with supplemented gadolinium for higher resolution (50‐µm) analysis.

Results

In vivo manganese‐enhanced MRI and deformation‐based morphometry correctly identified known cerebellar defects in Gbx2‐CKO mice, and novel phenotypes were discovered in the deep cerebellar nuclei and the vestibulo‐cerebellum, both validated using histology. Ex vivo micro‐MRI revealed subtle phenotypes in both the vestibulo‐cerebellum and the vestibulo‐cochlear organ, providing an interesting example of complementary phenotypes in a sensory organ and its associated brain region.

Conclusion

These results show the potential of three‐dimensional MRI for detecting and analyzing developmental defects in mouse models of neurodevelopmental diseases. Magn Reson Med 70:1707–1717, 2013. © 2013 Wiley Periodicals, Inc.
Whole‐heart coronary MRA with 100% respiratory gating efficiency: Self‐navigated three‐dimensional retrospective image‐based motion correction (TRIM)
Authors: Pang Jianing , Bhat Himanshu , Sharif Behzad , Fan Zhaoyang , Thomson Louise E. J. , LaBounty Troy , Friedman John D. , Min James , Berman Daniel S. , Li Debiao
Published: February 2013

Purpose

To develop a three‐dimensional retrospective image‐based motion correction technique for whole‐heart coronary MRA with self‐navigation that eliminates both the need to setup a diaphragm navigator and gate the acquisition.

Methods

The proposed technique uses one‐dimensional self‐navigation to track the superior–inferior translation of the heart, with which the acquired three‐dimensional radial k‐space data is segmented into different respiratory bins. Respiratory motion is then estimated in image space using an affine transform model and subsequently this information is used to perform efficient motion correction in k‐space. The performance of the proposed technique on healthy volunteers is compared with the conventional navigator gating approach as well as data binning using diaphragm navigator.

Results

The proposed method is able to reduce the imaging time to 7.1±0.5 min from 13.9±2.6 min with conventional navigator gating. The scan setup time is reduced as well due to the elimination of the navigator. The proposed method yields excellent image quality comparable with either conventional navigator gating or the navigator binning approach.

Conclusion

We have developed a new respiratory motion correction technique for coronary MRA that enables 1 mm3 isotropic resolution and whole‐heart coverage with 7 min of scan time. Further tests on patient population are needed to determine its clinical usage. Magn Reson Med 71:67–74, 2014. © 2013 Wiley Periodicals, Inc.
On some advanced thermo‐mechanical models for saturated clays
Authors: Hong P. Y. , Pereira J. M. , Tang A. M. , Cui Y. J.
Published: February 2013

This paper aims to evaluate the performance of several recent constitutive models in simulating the thermo‐mechanical behaviour of saturated clays. A classic thermo‐mechanical test on natural Boom Clay, commonly used in constitutive modelling, was first clarified. Different methods commonly used to measure volumetric strain in drained heating tests were then discussed. Model evaluation was performed in terms of thermodynamic and elasto‐plastic requirements. The capability of the models to capture the observed behaviour was assessed on the basis of the experimental evidence. It was shown that all the models provide reasonable predictions of the thermo‐mechanical behaviour of saturated clays. However, each constitutive model has its own limitations or unclear points from the theoretical point of view. Copyright © 2013 John Wiley & Sons, Ltd.
Construction of baselines for VoIP traffic management on open MANs
Authors: Gibeli Luis Henrique , Breda Gean Davis , Miani Rodrigo Sanches , Zarpelão Bruno Bogaz , de Souza Mendes Leonardo
Published: February 2013

In the last century, owing to the constant evolution of technologies telecommunication networks have become increasingly robust, being able to support multiple services. These services are part of the heterogeneous network traffic that can be carried through the Internet. Many of these services, including VoIP, are latency sensitive. In other words, this means that their quality depends directly on the network quality of service. Since users tend to become more sensitive with the instability and unavailability of the network, it is important to improve traffic management. A particular type of data that could be used to improve VoIP traffic management is the Internet Protocol Detail Record (IPDR). IPDRs are tickets created by all VoIP call attempts which contain a group of information related to the call history. Because of its full range of information, IPDRs can be used to create VoIP traffic baselines. This paper presents the development of baselines based on IPDRs to support VoIP traffic management in open‐access Metropolitan Area Networks (MAN). Copyright © 2013 John Wiley & Sons, Ltd.
Application and evaluation of the method of ellipses for measuring the orientation of long, semi‐flexible fibers
Authors: Hofmann John T. , Vélez‐Garcia Gregorio M. , Baird Donald G. , Whittington Abby R.
Published: February 2013

The method of ellipses (MoE) is a common experimental technique utilized to quantitatively determine the orientation state of a population of rigid fibers within a fiber–polymer composite. In this research, the validity of applying the MoE to long, semi‐flexible fiber systems in which the majority of fibers are flexible is discussed. The components of the orientation tensor were first determined for a composite formed by a homogenous, simple shear field. The minimum acceptable image analysis width, or bin width, for the selected geometry was found to be ∼5.5 mm, or 1.4 times the average fiber length. This modified bin width was then used to determine the orientation at multiple percentages of flow within an injection‐molded, center‐gated disc, and compared to orientation values obtained utilizing the traditional, 0.7‐mm bin width. The results show that the traditional, 0.7‐mm bin width is sufficient for analysis of the center‐gated geometry. This fortuitous result is attributed to the axisymmetric nature of the center‐gated geometry, and the highly transverse fiber alignment seen within the samples, especially at moderate to high percentages of flow. In more complex flows, it is expected that the conventional bin width will not apply. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers
A New Application of Charged Aerosol Detection in Liquid Chromatography for the Simultaneous Determination of Polar and Less Polar Ginsenosides in Ginseng Products
Authors: Jia Shaodong , Li Jing , Yunusova Nozimakhonim , Park Jeong Hill , Kwon Sung Won , Lee Jeongmi
Published: February 2013

Introduction

Conventional liquid chromatographic methods coupled with ultraviolet or evaporative light scattering detection are not sensitive enough to determine both polar and less polar ginsenosides at low concentrations.

Objective

To establish a liquid chromatography–charged aerosol detection method for the simultaneous determination of polar and less polar ginsenosides in a variety of ginseng products

Methods

Fourteen polar and less polar ginsenosides were extracted and concentrated by solid phase extraction. These were subsequently baseline‐separated on a conventional reversed‐phase C18‐column (250 mm × 4.6 mm, 5 µm) with a simple mobile phase consisting of water and acetonitrile. Components were then detected by means of charged aerosol detection.

Results

The method developed allowed the simultaneous determination of six polar ginsenosides (Rg1, Re, Rb1, Rc, Rb, Rd) and eight less polar ginsenosides (Rg6, F4, Rk3, Rh4, Rg3(S), Rg3(R), Rk1, Rg5) in a single chromatographic run. Further, the method was linear (R2 > 0.99), accurate (relative recoveries, 90–112%), and precise (intraday RSD < 5.7% and interday RSD < 10.6%) within the concentration range tested. The method sensitivity was measured in terms of the limit of detection, which ranged from 0.5 to 4.0 µg/mL.

Conclusion

Concentrations of 14 ginsenosides were determined simultaneously in one homemade red ginseng and 13 commercial ginseng products of different types (liquid and solid samples), and results showed that ginsenoside content varied significantly among the samples tested. The method developed could serve as a useful analytical tool for the quality control of ginseng products. Copyright © 2013 John Wiley & Sons, Ltd.
Raising antibodies against circulating foetal cells from maternal peripheral blood
Authors: Sørensen Morten Dræby , Melchjorsen Connie Jenning , Mandrup Ole Aalund , Kristensen Peter
Published: February 2013

Objective

Cells of foetal origin circulating in the maternal peripheral bloodstream present a unique source for non‐invasive prenatal diagnostics. The aims of this study were to raise antibodies against identified circulating foetal cells from the maternal blood, test the properties of these antibodies and to determine the foetal cell type recognised by the antibodies.

Method

Cells from a male foetus were identified in a maternal blood sample by FISH analysis of the X‐ and Y‐ chromosomes. The identified cells were subjected to phage display selection using a novel single cell selection strategy. Selected antibodies were tested by immunocytochemistry on foetal and adult tissue arrays, an endothelial cell line, and peripheral blood mononuclear cells.

Results

Three identified foetal cells subjected to antibody selection, yielded a total of 12 antibodies. Three antibodies gave distinct staining patterns on tissue arrays, and endothelial cells. One antibody, SF1.3, shows specific staining of a subpopulation of peripheral blood mononuclear cells, including a fraction of CD34 positive cells.

Conclusion

These findings indicate that the identified foetal cells could have been progenitor cells of haematopoietic origin. The antibody SF1.3 could be a potential tool toward non‐invasive prenatal diagnostics. © 2013 John Wiley & Sons, Ltd.
Improvement in toughness and crystallization of poly(L‐lactic acid) by melt blending with ethylene/methyl acrylate/glycidyl methacrylate terpolymer
Authors: Zhang Xin , Li Yi , Han Lijing , Han Changyu , Xu Kun , Zhou Chao , Zhang Mingyao , Dong Lisong
Published: February 2013

Melt blending of poly(lactic acid) (PLA) and ethylene/methyl acrylate/glycidyl methacrylate terpolymer (EGA) containing relatively high‐concentration epoxide groups (8 wt%) was performed to improve the toughness and crystallization of PLA. The results of nonisothermal and isothermal crystallization investigation showed that the addition of EGA accelerated the crystallization rate and increased the final crystallinity of PLA in the blends. Significant enhancement in toughness and flexibility of PLA were achieved by the incorporation of the EGA elastomer. When 20 wt% EGA added, the impact strength increased from 3.0 kJ m−2 of neat PLA to 59.8 kJ m−2 and the elongation at break increased from 4.9 to 232.0%. The failure mode changed from brittle fracture of neat PLA to ductile fracture of the blend. POLYM. ENG. SCI., 53:2498–2508, 2013. © 2013 Society of Plastics Engineers
Cu2ZnSnSe4 thin film solar cells produced via co‐evaporation and annealing including a SnSe2 capping layer
Authors: Redinger Alex , Mousel Marina , Djemour Rabie , Gütay Levent , Valle Nathalie , Siebentritt Susanne
Published: February 2013

Cu2ZnSnSe4 (CZTSe) thin film solar cells have been produced via co‐evaporation followed by a high‐temperature annealing. In order to reduce the decomposition of the CZTSe, a SnSe2 capping layer has been evaporated onto the absorber prior to the high‐temperature treatment. This eliminates the Sn losses due to SnSe evaporation. A solar cell efficiency of 5.1% could be achieved with this method. Moreover, the device does not suffer from high series resistance, and the dominant recombination pathway is situated in the absorber bulk. Finally, different illumination conditions (white light, red light, and yellow light) reveal a strong loss in fill factor if no carriers are generated in the CdS buffer layer. This effect, known as red‐kink effect, has also been observed in the closely related Cu(In,Ga)Se2 thin film solar cells. Copyright © 2013 John Wiley & Sons, Ltd.
Flame retardant high oleic sunflower oil‐based thermosetting resins through aza‐ and phospha‐michael additions
Authors: Moreno Maryluz , Lligadas Gerard , Ronda Juan C. , Galià Marina , Cádiz Virginia
Published: February 2013

Phosphorus‐containing thermosetting resins derived from high oleic sunflower oil were prepared through phospha‐Michael addition of a difunctional secondary phosphine oxide, the 1,3‐bis(phenylphosphino)propane dioxide on the α,β‐unsaturated ketone derived from high oleic acid (ETR). The aim of this approach was to introduce phosphorus and to crosslink the material in one single step. Materials with increasing aromatic content were also prepared by addition 4,4′‐diaminodiphenylmethane and co‐crosslinking through aza‐Michael addition. The kinetics of the phospha and aza‐Michael additions was investigated using the enone derivative of methyl oleate (EO) in presence of BF3·Et2O as catalyst and in absence of catalyst at different temperatures. Competitive experiments showed that phospha‐Michael addition proceeds faster than the aza‐Michael addition. The new triglyceride‐based thermosets containing up to 4.2% of P, were characterized and their thermal and flame retardant properties evaluated. Limiting oxygen index values increase from 21.5 for the phosphorus free material up to 38.0 for the final material with 4.2% P content. These results demonstrate that the flame retardant properties of vegetable oil‐based thermosets can be significantly improved by adding covalently bonded phosphorus to the polymer. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
A macromonomer approach to the synthesis of poly(1,1‐bis(ethoxycarbonyl)‐2‐vinyl cyclopropane‐graft‐dimethyl siloxane)
Authors: Sarker Prodip , Rehman Saif U. R. , Rimmer Stephen
Published: February 2013

Poly(1,1‐bis(ethoxycarbonyl)‐2‐vinyl cyclopropane (ECVP)‐graft‐dimethyl siloxane) copolymers were prepared using a macromonomer approach. Poly(dimethyl siloxane) (PDMS) macromonomers were prepared by living anionic polymerization of cyclosiloxanes followed by sequential chain‐end capping with allyl chloroformate. These macromonomers were then copolymerized with ECVP. MALDI‐ToF mass spectrometry and 1H NMR spectroscopy were used to show that the macromonomers had approximately 80% of the end groups functionalized with allyl carbonate groups. Gradient polymer elution chromatography showed that high yields of the graft copolymers were obtained, along with only small fractions of the PECVP and PDMS homopolymers. Differential scanning calorimetry showed that the low glass transition temperature (Tg) of the PDMS component could be maintained in the graft copolymers. However, the Tg was a function of polymer composition and the polymers produced had Tgs that ranged from −50 to −120 °C. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
Statistical fluorinated copolymers from heterogeneous atom transfer radical copolymerization of styrene and 2,2,2‐trifluoroethyl methacrylate with similar reactivity ratios
Authors: Zhang Ganwei , Hu Jiwen , He Guping , Zou Hailiang , Liu Feng , Hou Chengmin , Luo Hongsheng , Tu Yuanyuan
Published: February 2013

Fluorinated copolymers with statistical structure of azeotropic or gradient composition were prepared from heterogeneous atom transfer radical copolymerizations of styrene (S) and 2,2,2‐trifluoroethyl methacrylate (T). The polymerization kinetic studies show that while the propagation rate constant of S increased with a decreasing S content in the comonomer feed ratio, the propagation rate of T decreased with decreases of the S content in the comonomer feed ratio. The polymerization rate and controllability of the heterogeneous ATRP of S and T were regulated by the solubility of Cu(II)/ligand in the reaction mixture, based on a mechanistic analysis and solubility tests of the Cu(II)/ligand system in the reaction media. The reactivity ratios of S and T were 0.22 and 0.35, as evaluated from kinetic analysis of monomer conversions higher than 35%. These statistical polymers self‐assembled in T to form giant vesicles GVs) with broad diameter distribution in the range of 1–10 μm. Unlike the methods normally used to prepare gradient copolymers by spontaneous controlling with feeding model or batch polymerization of comonomers with obvious differences in the reactivity ratio, in this contribution, we report a novel synthetic strategy for preparing gradient copolymers can also be prepared from both monomers with very similar reactivity ratio. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
Benzoin type photoinitiator for free radical polymerization
Authors: Esen Duygu Sevinc , Arsu Nergis , Da Silva José P. , Jockusch Steffen , Turro Nicholas J.
Published: February 2013

Benzoin, a popular photoinitiator for free radical polymerization of vinyl monomers, was improved by introduction of two methyl thioether substituents. This new benzoin derivative showed an about 50 times higher light absorption in the near‐UV spectral region and performed better than the unsubstituted benzoin in polymerization experiments in bulk solutions or films of acrylate monomers when low initiator concentrations are used. Laser flash photolysis, low temperature luminescence experiments and photoproduct studies by mass spectrometry suggest that a slow α‐cleavage mechanism (kα = 2.2 × 105 s−1) from the electronic triplet state with a quantum yield of 0.1 is the primary photoreaction to generate the initiating free radicals. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
Ligand‐free SET‐DTLRP of MMA at room temperature
Authors: Wang Wenxiang , Zhao Junfei , Zhang Wei , Zhu Jian , Zhang Zhengbiao , Zhu Xiulin
Published: February 2013

An iodine‐based initiator, 2‐iodo‐2‐methylpropionitrile (CPI), was utilized for the single‐electron transfer and degenerative chain transfer mediated living radical polymerization (SET‐DTLRP) of methyl methacrylate (MMA) in the absence of ligand, at ambient temperature. The CPI‐initiated ligand‐free polymerizations manifested reasonable control over molecular weights with relatively narrow distributions (Mw/Mn ≤ 1.35). The living nature of the polymers was further confirmed by successful chain extension reaction and 1H NMR with high chain‐end fidelity (∼96%). Screening of the available solvents suggested that the controllability of this polymerization was highly dependent on the kind of solvents, wherein dimethyl sulfoxide was a better solvent for a controlled molecular weight. The proposed ligand‐free SET‐DTLRP initiated by CPI was intriguing since it would dramatically decrease the concentration of Cu(0) ions both in polymerization system and resultant polymer, and provided a more economical and eco‐friendly reversible‐deactivation radical polymerization technique. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
Constructing novel double‐bond‐containing well‐defined amphiphilic graft copolymers via successive Ni‐catalyzed living coordination polymerization and SET‐LRP
Authors: Li Yongjun , Lu Guolin , Dai Bin , Xu Caixia , Huang Xiaoyu
Published: February 2013

A series of polyallene‐based well‐defined amphiphilic graft copolymers, poly(6‐methyl‐1,2‐heptadiene‐4‐ol)‐g‐poly(2‐(diethylamino)ethyl methacrylate) (PMHDO‐g‐PDEAEMA), was synthesized through the grafting‐from technique. First, double‐bond‐containing PMHDO backbone bearing pendant hydroxyls was prepared via [(η3‐allyl)NiOCOCF3]2‐initiated living coordination polymerization of 6‐methyl‐1,2‐heptadiene‐4‐ol (MHDO). The pendant hydroxyls in the homopolymer were then reacted with 2‐chloropropionyl chloride to give PMHDO‐Cl macroinitiator. Finally, hydrophilic PDEAEMA side chains were formed by single electron transfer‐living radical polymerization (SET‐LRP) of 2‐(diethylamino)ethyl methacrylate (DEAEMA) in THF/H2O initiated by the macroinitiator using CuCl/Me6TREN as catalytic system to afford PMHDO‐g‐PDEAEMA graft copolymers. The narrow molecular weight distributions (Mw/Mn ≤ 1.35) and kinetics experiment showed the controllability of SET‐LRP graft copolymerization of DEAEMA. The critical micelle concentration (cmc) of PMHDO‐g‐PDEAEMA amphiphilic graft copolymer in aqueous media was determined by fluorescence probe technique and the relationships between cmc and pH or salinity were also investigated. Micellar morphologies were preliminarily explored using transmission electron microscopy. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
Modeling controlled photodegradation in optically thick hydrogels
Authors: Tibbitt Mark W. , Kloxin April M. , Anseth Kristi S.
Published: February 2013

There is a growing interest in developing dynamically responsive hydrogels whose material properties are modulated by environmental cues, including with light. These photoresponsive hydrogels afford spatiotemporal control of material properties through an array of photoaddition and photodegradation reactions. For photoresponsive hydrogels to be utilized most effectively in a broad range of applications, the photoreaction behavior should be well understood, enabling the design of dynamic materials with uniform or anisostropic material properties. Here, a general statistical‐kinetic model has been developed to describe controlled photodegradation in hydrogel polymer networks containing photolabile crosslinks. The heterogeneous reaction rates that necessarily accompany photochemical reactions were described by solving a system of partial differential equations that quantify the photoreaction kinetics in the material. The kinetics were coupled with statistical descriptions of network structure in chain polymerized hydrogels to model material property changes and mass loss that occur during the photodegradation process. Finally, the physical relevance of the model was demonstrated by comparing model predictions with experimental data of mass loss and material property changes in photodegradable, PEG‐based hydrogels. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
A novel photo‐acid generator bound molecular glass resist with a single protecting group
Authors: Kasai Tatsuaki , Higashihara Tomoya , Ueda Mitsuru
Published: February 2013

A novel photo‐acid generator (PAG) bound molecular glass photoresist with a single protecting group has been developed as a promising resist material for use in microelectronics. This single component molecular resist was prepared in four steps starting from 9,9‐bis(4‐hydroxyphenyl)fluorene. The single component molecular resist exhibited good thermal properties, such as a 10% weight loss temperature of 200 °C and a glass transition temperature of 91 °C. This resist showed a good sensitivity of 60 μC/cm2 with e‐beam exposure (50 keV). On the other hand, the fine pattern with a half‐pitch of 50 nm in the presence of 4 wt % quencher, trioctylamine, was obtained using electron‐beam (100 keV) lithography. The LER value was 8.2 nm (3σ, 60 nm half‐pitch patterns). © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
Thermally induced shape‐memory effects in polymers: Quantification and related modeling approaches
Authors: Heuchel Matthias , Sauter Tilman , Kratz Karl , Lendlein Andreas
Published: February 2013

Thermo‐sensitive polymers, which are capable to exhibit a dual‐, triple‐, or multi‐shape effect or a temperature‐memory effect (TME), characterized by a controlled shape change in a predefined way, are of current technological interest for designing and realization of actively moving intelligent devices. Here, the methods for the quantitative characterization of shape‐memory effects in polymers and recently developed thermomechanical modeling approaches for the simulation of dual‐, triple‐, and multi‐shape polymers as well as materials that exhibit a TME are discussed and some application oriented models are presented. Standardized methods for comprehensive quantification of the different effects and reliable modeling approaches form the basis for a successful translation of the extraordinary achievements of fundamental research into technological applications. © 2013 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013
Polymer grafted nanoparticles: Effect of chemical and physical heterogeneity in polymer grafts on particle assembly and dispersion
Authors: Jayaraman Arthi
Published: February 2013

Macroscopic properties of polymer nanocomposites depend on the microscopic composite morphology of the constituent nanoparticles and polymer matrix. One way to control the spatial arrangement of the nanoparticles in the polymer matrix is by grafting the nanoparticle surfaces with polymers that can tune the effective interparticle interactions in the polymer matrix. A fundamental understanding of how graft and matrix polymer chemistries and molecular weight, grafting density, and nanoparticle size, and chemistry affect interparticle interactions is needed to design the appropriate polymer ligands to achieve the target morphology. Theory and simulations have proven to be useful tools in this regard due to their ability to link molecular level interactions to the morphology. In this feature article, we present our recent theory and simulation studies of polymer grafted nanoparticles with chemical and physical heterogeneity in grafts to calculate the effective interactions and morphology as a function of chemistry, molecular weights, grafting densities, and so forth. © 2013 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013
Modeling the membrane environment has implications for membrane protein structure and function: Influenza A M2 protein
Authors: Zhou Huan‐Xiang , Cross Timothy A.
Published: February 2013

The M2 protein, a proton channel, from Influenza A has been structurally characterized by X‐ray diffraction and by solution and solid‐state NMR spectroscopy in a variety of membrane mimetic environments. These structures show substantial backbone differences even though they all present a left‐handed tetrameric helical bundle for the transmembrane domain. Variations in the helix tilt influence drug binding and the chemistry of the histidine tetrad responsible for acid activation, proton selectivity and transport. Some of the major structural differences do not arise from the lack of precision, but instead can be traced to the influences of the membrane mimetic environments. The structure in lipid bilayers displays unique chemistry for the histidine tetrad, which binds two protons cooperatively to form a pair of imidazole‐imidazolium dimers. The resulting interhistidine hydrogen bonds contribute to a three orders of magnitude enhancement in tetramer stability. Integration with computation has provided detailed understanding of the functional mechanism for proton selectivity, conductance and gating of this important drug target.
Carbon doped asymmetric cubic AlN/GaN multi quantum well structures for high electrical isolation to 3C‐SiC substrates
Authors: Zado A. , As D. J.
Published: February 2013

In this work we present a novel method of the electrical separation of the substrate and the hetero junction field effect transistor device. For the epitaxial growth of our structures free standing 3C‐SiC (001) substrates with a free carrier concentration of n=2.7×1018 cm‐3 and a resistivity of ρ=34 mΩcm were used. On a 50 nm c‐GaN buffer layer an asymmetric multi quantum well structure consisting of 5 periodes of two cubic GaN:C asymmetric QWs (1 nm and 2 nm) embed‐ded between 3 nm thick c‐AlN:C barriers. A 50 nm c‐GaN cap layer completes the sample structure. A detailed conduction band profile and the quantized electron states within the asymmetric quantum well were calculated using a 1D Poisson‐Schrödinger‐solver. The structural properties were analyzed by atomic force microscopy and high resolution x‐ray diffraction. Current‐voltage measurements of these structures showed an increase of the serial resistivity by six orders of magnitude (from 5 mΩ to 8 kΩ) compared to an unstructured c‐GaN reference sample. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
CHVPE growth of AlGaN‐based UV LEDs
Authors: Kurin Sergey , Antipov Andrey , Barash Iosif , Roenkov Alexander , Helava Heikki , Tarasov Sergey , Menkovich Ekaterina , Lamkin Ivan , Makarov Yuri
Published: February 2013

In this paper, we present results on development of ultraviolet light‐emitting diodes (UV LEDs) based on GaN/AlGaN heterostructures grown on Al2O3 (0001) substrates by chloride‐hydride vapour phase epitaxy (CHVPE). Both packaged and unpackaged UV LED dies were fabricated. The peak wavelengths of dies were in the range of 360–365 nm with a typical FWHM of 10–13 nm. UV LEDs proved performance capability at current density up to 125 A/cm2. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of Storage in a Low Oxygen Gas Atmosphere on Colour and Sensory Properties of Pork Loins
Authors: Tatjana Tasić , Petrović Ljiljana , Ikonić Predrag , Lazić Vera , Jokanović Marija , Džinić Natalija , Tomović Vladimir , Šarić Ljubiša
Published: February 2013

The objective of this study was to examine the quality characteristics of packaging materials and packaging units, and the viability and acceptability of the colour and sensorial properties of fresh pork meat during storage in low oxygen and high carbon dioxide modified atmosphere packaging up to 16 days at two temperatures (0°C and 4°C), as well as the sensorial properties of cooked meat. Packaging materials had good mechanical and barrier properties and were suitable for packaging in selected atmosphere. The concentration of oxygen during the whole storage period was less than 0.5% at both temperatures. The proportion of red colour (a*) was successfully maintained although the colour was slightly darker (L*) and the sensory value was lower when evaluated at the end of the storage period. Based on the obtained results and discussion, it can be concluded that samples packaged in a modified atmosphere with 40% CO2 and 60% N2 can be stored at 0°C for 15 days and at 4°C for 10 days. Samples had a good sensory quality until the 16th day, with the best results achieved on the 7th day. Copyright © 2013 John Wiley & Sons, Ltd.
Migration of Aluminum and Silicon from PET/Clay Nanocomposite Bottles into Acidic Food Simulant
Authors: Farhoodi Mehdi , Mousavi Seyed Mohammad , Sotudeh‐Gharebagh Rahmat , Emam‐Djomeh Zahra , Oromiehie Abdolrasul
Published: February 2013

Poly(ethylene terephthalate) (PET)/clay nanocomposite samples were prepared by melt blending PET and Cloisite 20A nanoparticles. A stretch blow‐moulding machine was used to produce bottles from neat PET and PET nanocomposite. Tests were performed on the migration of aluminum and silicon from PET nanocomposite bottles into acidic food simulant. The samples were stored at room temperature (about 25°C) and 45°C for time durations ranging from 7 to 90 days. A specific surface of sheets (prepared from PET/clay nanocomposite) immersed in acidic food simulant, and two‐sided migration of Al and Si was investigated. According to X‐ray diffraction analysis, the nanoclays show intercalated structure in the PET matrix. Transmission electron microscopy and atomic force microscopy micrographs displayed both intercalation and exfoliation morphology for PET/clay nanocomposites. Inductively coupled plasma was used to quantify amounts of Al and Si that had migrated into the acidic food simulant. It was observed that the migration process is dependent on storage time and temperature, and the molar ratio of aluminum and silicon in the acidic aqueous solution (Al/Si)aq to the ratio in the solid phase of prepared nanocomposites (Al/Si)solid was about 23% higher in the samples stored at 45°C. Copyright © 2013 John Wiley & Sons, Ltd.
Ab‐Initio calculations of the CO adsorption and dissociation on substitutional Fe–Cu surface alloys relevant to Fischer–Tropsch Synthesis: bcc‐(Cu)Fe(100) and fcc‐(Fe)Cu(100)
Authors: Elahifard MohammadReza , Fazeli Elham , Joshani Azadeh , Gholami MohammadReza
Published: February 2013

Direct CO dissociation is seen the main path of the first step in the Fischer–Tropsch Synthesis (FTS) on the reactive iron surfaces. Cu/Fe alloy film is addressed with various applications over face‐centered‐cubic (fcc)‐Cu and body‐centered‐cubic (bcc)‐Fe in the FTS, i.e. preventing iron carbide formation (through direct CO dissociation) by moderating the surface reactivity and facilitating the reduction of iron surfaces, respectively. In this study by density functional theory, the stable configurations of CO molecule on various Cu/Fe alloys over fcc‐Cu(100) and bcc‐Fe(100) surfaces with different CO coverage (25% and 50%) have been evaluated. Our results showed that the ensemble effect plays a fundamental role to CO adsorption energy on the surface alloys over bcc‐Fe(100); on the other hand, the ligand effect determines the CO stability on the fcc‐Cu(100) surface alloys. CO dissociation barrier was also calculated on the surface alloys that showed although the CO dissociation process is thermodynamically possible on the more reactive surface alloys, but according to their high barrier, CO dissociation does not occur directly on these surfaces. Copyright © 2013 John Wiley & Sons, Ltd.
Stress corrosion cracking behaviour of conventional and innovative aluminium alloys for aeronautic applications
Authors: Astarita A. , Bitondo C. , Squillace A. , Armentani E. , Bellucci F.
Published: February 2013

In this work, the stress corrosion cracking (SCC) behaviour of both innovative and conventional friction stir welded aluminium alloys was investigated. Similar butt joints were realized and tested; in particular, four different alloys for aeronautic applications were studied: AA2024 T3, AA2139 T3, AA2198 T3 and AA6056 T4. SCC tests were carried out following the international standards using a dedicated machine designed following as prescribed by the standards. The results showed that all the joints passed the tests, but pitting and generalized corrosion happens on all the specimens tested. Furthermore, an influence of the applied load on the corrosion behaviour was observed. Copyright © 2013 John Wiley & Sons, Ltd.
A Study of Cognitive Vulnerability–Stress Model of Depressive Symptoms among Chinese Adolescents
Authors: Cui Lixia , Shi Guangyuan , Oei Tian P. S.
Published: February 2013

The objective of the present study is to test the validity of the integrated cognitive model of depression proposed by Kwon and Oei (1994) with a Chinese adolescent sample. A two‐wave panel design was used. We hypothesized that the interaction between dysfunctional attitudes measured at time 1 and adolescents' negative life events experienced between times 1 and 2 would predict changes in the frequency of automatic thoughts between times 1 and 2. We further hypothesized that changes in the frequency of automatic thoughts would, in turn, predict changes in the severity of depressive symptoms. Participants were 329 Chinese adolescents. As a comparison, we tested three other competing models: linear mediation, alternative aetiologies and symptom models. All participants completed the Adolescent Self‐Rating Life Events Checklist, Dysfunctional Attitudes Scale, Automatic Thoughts Questionnaire and Center for Epidemiological Studies Depression Scale on two occasions—5 months apart. Path analysis was used to test all models. Results of the path analysis indicated that the integrated cognitive model showed an adequate fit for the Chinese adolescent data. During phases of increased depression, dysfunctional attitudes were common cognitive moderators of depression, whereas automatic thoughts were specific cognitive mediators of depression. Copyright © 2013 John Wiley & Sons, Ltd.
Concise Review: Preclinical Studies on Human Cell-Based Therapy in Rodent Ischemic Stroke Models: Where Are We Now after a Decade?
Authors: Leong Wai Khay , Lewis Martin D. , Koblar Simon A.
Published: February 2013

Stroke, a debilitating brain insult, afflicts millions of individuals globally each year. In the last decade, researchers have investigated cell-based therapy as an alternative strategy to improve neurological outcome following stroke. This concise review critically examines preclinical reports using human adult and fetal stem/progenitor cells in rodent models of ischemic stroke. As we enter the second decade of study, we should aim to optimize our collective likelihood to translational success for stroke victims worldwide. We advocate international consensus recommendations be developed for future preclinical research.
Therapeutic Efficacy and Fate of Bimodal Engineered Stem Cells in Malignant Brain Tumors
Authors: Martinez-Quintanilla Jordi , Bhere Deepak , Heidari Pedram , He Derek , Mahmood Umar , Shah Khalid
Published: February 2013

Therapeutically engineered stem cells (SC) are emerging as an effective tumor-targeted approach for different cancer types. However, the assessment of the long-term fate of therapeutic SC post-tumor treatment is critical if such promising therapies are to be translated into clinical practice. In this study, we have developed an efficient SC-based therapeutic strategy that simultaneously allows killing of tumor cells and assessment and eradication of SC after treatment of highly malignant glioblastoma multiforme (GBM). Mesenchymal stem cells (MSC) engineered to co-express the prodrug converting enzyme, herpes simplex virus thymidine kinase (HSV-TK) and a potent and secretable variant of tumor necrosis factor apoptosis-inducing ligand (S-TRAIL) induced caspase-mediated GBM cell death and showed selective MSC sensitization to the prodrug ganciclovir (GCV). A significant decrease in tumor growth and a subsequent increase in survival were observed when mice bearing highly aggressive GBM were treated with MSC coexpressing S-TRAIL and HSV-TK. Furthermore, the systemic administration of GCV post-tumor treatment selectively eliminated therapeutic MSC expressing HSV-TK in vitro and in vivo, which was monitored in real time by positron emission-computed tomography imaging using 18F-FHBG, a substrate for HSV-TK. These findings demonstrate the development and validation of a novel therapeutic strategy that has implications in translating SC-based therapies in cancer patients.