bluuebunny/crossref_metadata_2025_split huggingface dataset:
In situ encapsulation of hydrogel in ultrafine fibers by suspension electrospinning
Authors: Han Fengxuan , Zhang Hong , Zhao Jin , Zhao Yunhui , Yuan Xiaoyan 
Published: July 2012

AbstractComposite ultrafine fibers of hydrogel/polylactide copolymer were successfully electrospun from water‐in‐oil suspensions. Effects of the suspension composition on the morphology and microstructure of the obtained fibers were investigated, including both aqueous phase and oily phase, that is, hydrogel (chitosan or gelatin), polylactide copolymers [poly(ethylene glycol)‐b‐poly (L‐lactide‐co‐caprolactone) (PELCL) or poly(L‐lactide‐co‐glycolide) (PLGA)], organic solvents and surfactants. Scanning electron micrographs showed that mixed solvents of chloroform and N,N‐dimethyl formamide or 2,2,2‐trifluoroethanol were preferred to form beads‐free ultrafine fibers with diameter in the range of 230–470 nm. With ethyl acetate as organic solvent, compared with chitosan hydrogel/PELCL composite fibers, chitosan hydrogel/PLGA fibers showed narrower distribution of diameter in 230–590 nm. Different hydrogel and surfactants used in this experiment had slight effects on the morphology of the obtained fibers, whereas transmission electron micrographs exhibited chitosan and gelatin hydrogel could be in situ encapsulated in the fibers discontinuously. This method may promise a new aqueous reservoir for encapsulation and controlled release of bioactive agents. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers
Synthesis of new organic semiconductors based on poly(2‐anilinoethanol) doped with different acids and investigation of their electro‐optical properties
Authors: Ahlatcıoğlu E. , Şenkal B.F. , Yakuphanoğlu F. , Mansour Sh.A. 
Published: July 2012

AbstractThe polyaniline (PANI) was synthesized using different dopant acids (iminodiacetic, methanesulfonic, phosphoric, and boron trifuoride) using oxidative polymerization method. These obtained new polymers were characterized by using spectrophotometric methods such as FTIR, UV–vis. The calculated value of the optical energy gap for the doped investigated polymer was reached to 3.70 eV for PANI‐OH doped by boron trifuoride. The conductivity of the polymers was also investigated. The direct current (dc) conductivity as a function of temperature for the doped polymers has been studied. The results show increase in the conductivity with increase in temperature. Also, the value of dc conductivity at room temperature was found to be greater than that of the undoped PANI by nearly one to four orders of magnitude with respect to the used dopant acid. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Investigation of the effect of hydrolysis products of postconsumer polyethylene terephthalate bottles on the properties of alkyd resins
Authors: Tuna Ö. , Bal A. , Güçlü G. 
Published: July 2012

AbstractHydrolysis of waste polyethylene terephthalate (PET) flakes obtained from grinding postconsumer bottles was carried out at 200–230°C and molar ratios of PET/H2O were taken as 1/5; 1/10; 1/20. The reaction products, when extracted with boiling water, yielded a water soluble crystallizable fraction (WSCF) and a water insoluble fraction (WIF). These fractions were characterized by acid and hydroxyl value determinations and DSC analysis. WSCF and WIF were used for preparation of alkyd resins. Five long oil alkyd resins were prepared from phthalic anhydride (PA) (reference alkyd resin) or hydrolysis products of the waste PET (PET‐based alkyd resin), pentaerithrithol (PE), soybean oil fatty acid (SOFA), and ethylene glycol (EG). Film properties and thermal degradation stabilities of these alkyd resins were investigated. Drying time, hardness, alkaline resistance, and thermal oxidative degradation resistance of the PET‐based alkyd resins are better than these properties of reference resin. The results show that hydrolysis products of waste PET obtained from postconsumer bottles are suitable for manufacturing of alkyd resins. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
A one‐pot method to prepare transparent poly(methyl methacrylate)/montmorillonite nanocomposites using imidazolium‐based ionic liquids
Authors: Xu Hong , Tong Fangfang , Yu Jian , Wen Lixiong , Zhang Jun , He Jiasong 
Published: July 2012

AbstractPoly(methyl methacrylate) (PMMA)/montmorillonite (MMT) nanocomposites were prepared by a new one‐pot technique, where the hydrophilic Na‐MMT layers were decorated with hydrophobic 1‐dodecyl‐3‐methylimidazolium hexafluorophosphate (C12mimPF6) ionic liquid in situ during melt blending with PMMA and intercalation of polymer chains took place subsequently. The in situ modification and intercalation of Na‐MMT were confirmed using X‐ray diffraction and transmission electron microscopy. The combination of the compatible C12mimPF6 with PMMA and the good dispersion of MMT layers at the nanoscale rendered the resultant PMMA/MMT nanocomposites with improved optical transparency, thermal stability and mechanical properties. Copyright © 2012 Society of Chemical Industry
Preparation of ‘click’ hydrogels from polyaspartamide derivatives
Authors: Huynh Ngoc‐Thach , Jeon Young‐Sil , Zrinyi Miklos , Kim Ji‐Heung 
Published: July 2012

AbstractLately, copper‐assisted azide–alkyne cycloaddition (CuAAC) has become a very interesting tool for synthesizing biocompatible polymer‐based materials such as hydrogels or microgels, which can be used as biomaterials for tissue engineering and drug delivery. Novel poly(2‐hydroxyethyl aspartamide)s (PHEAs) functionalized with pendent acetylene or azide groups were prepared from polysuccinimide, which is the thermal polycondensation product of aspartic acid, through successful ring‐opening reactions using propargylamine, 1‐azido‐2‐aminoethane and ethanolamine. The composition of the prepared copolymers was analyzed using 1H NMR spectroscopy. Clickable PHEA derivatives were crosslinked by mixing together in water with a catalyst system of Cu(I) and N, N, N′, N′, N″‐pentamethyldiethylenetriamine, a type of Huisgen's 1,3‐dipolar azide‐alkyne cycloaddition. The reaction of the polymers resulted in a chemoselective coupling between alkynyl and azido functional groups with multiple formation of triazole crosslinks to give hydrogels. The triazole linkages in the hydrogels are highly stable and may also play a role in swelling behavior. PHEA‐based hydrogels were also obtained by the crosslinking of azide‐ or alkyne‐modified PHEA with a small‐molecule crosslinker. The hydrogels prepared using these two methods were characterized by their degree of swelling and the morphology of the hydrogels was confirmed using scanning electron microscopy. The approach we describe here presents a promising alternative to common chemical hydrogel preparation techniques, and these hydrogels seem to possess structures having potential for a variety of industrial and biomedical applications. © 2012 Society of Chemical Industry
New ladder‐type conjugated polymer with broad absorption, high thermal stability, and low band gap
Authors: Wang Shitao , Hong Wei , Ren Shendong , Li Jie , Wang Mao , Gao Xike , Li Hongxiang 
Published: July 2012

AbstractNew ladder‐type π‐conjugated polymer poly{6‐alkyl‐pyrrolo[3,2‐b:4,5‐b′]bis‐[1,4]benzothiazine} (PPBBTZ) was synthesized through a simple method. PPBBTZ showed good solubility in organic solvents (such as chloroform, tetrahydrofuran, chlorobenzene, o‐dichlorobenzene) and high thermal stability (decomposition temperatures up to 323 °C and 299 °C in nitrogen and air, respectively). The highest occupied molecular orbital and lowest unoccupied molecular orbital energy level estimated from electrochemistry result and absorption spectrum were −5.46 and −3.81 eV, respectively, with a band gap of 1.65 eV. More interestingly, PPBBTZ displayed broad absorption from ultraviolet to visible light regions (200–750 nm). These properties suggested PPBBTZ was a good candidate in opto‐electronics. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Plasma Deposition of PEO‐Like Coatings with Aerosol‐Assisted Dielectric Barrier Discharges
Authors: Da Ponte Gabriella , Sardella Eloisa , Fanelli Fiorenza , d'Agostino Riccardo , Gristina Roberto , Favia Pietro 
Published: July 2012

AbstractIn this paper, we describe the deposition of PEO‐like coatings using dielectric barrier discharges (DBDs) fed with aerosols of the TEGDME organic precursor in helium. By properly tuning plasma parameters such as aerosol/carrier flow ratio, frequency of the electric field applied and input power, the deposition process could be modulated to obtain coatings with variable PEO character, from 50% (cell adhesive) to 70% (nonfouling), which are interesting for surface modification of biomaterials and biomedical devices. magnified image
Multistate approaches in computational protein design
Authors: Davey James A. , Chica Roberto A. 
Published: July 2012

AbstractComputational protein design (CPD) is a useful tool for protein engineers. It has been successfully applied towards the creation of proteins with increased thermostability, improved binding affinity, novel enzymatic activity, and altered ligand specificity. Traditionally, CPD calculations search and rank sequences using a single fixed protein backbone template in an approach referred to as single‐state design (SSD). While SSD has enjoyed considerable success, certain design objectives require the explicit consideration of multiple conformational and/or chemical states. Cases where a “multistate” approach may be advantageous over the SSD approach include designing conformational changes into proteins, using native ensembles to mimic backbone flexibility, and designing ligand or oligomeric association specificities. These design objectives can be efficiently tackled using multistate design (MSD), an emerging methodology in CPD that considers any number of protein conformational or chemical states as inputs instead of a single protein backbone template, as in SSD. In this review article, recent examples of the successful design of a desired property into proteins using MSD are described. These studies employing MSD are divided into two categories—those that utilized multiple conformational states, and those that utilized multiple chemical states. In addition, the scoring of competing states during negative design is discussed as a current challenge for MSD.
Effect of distribution and concentration of topically applied neonicotinoid insecticides in buffalograss, Buchloe dactyloides, leaf tissues on the differential mortality of Blissus occiduus under field conditions
Authors: Stamm Mitchell D , Heng‐Moss Tiffany M , Baxendale Frederick P , Siegfried Blair D , Gaussoin Roch E , Snow Daniel D , Cassada David A 
Published: July 2012

AbstractBACKGROUND: Neonicotinoid insecticides are generally efficacious against many turfgrass pests, including several important phloem‐feeding insects. However, inconsistencies in control of western chinch bugs, Blissus occiduus, have been documented in field efficacy studies. This research investigated the efficacy of three neonicotinoid insecticides (clothianidin, imidacloprid and thiamethoxam) against B. occiduus in buffalograss under field conditions and detected statistically significant differences in B. occiduus numbers among treatments. A subsequent study documented the relative quantity and degradation rate of these insecticides in buffalograss systemic leaf tissues, using HPLC.RESULTS: Neonicotinoid insecticides initially provided significant reductions in B. occiduus numbers, but mortality diminished over the course of the field studies. Furthermore, while all three neonicotinoids were present in the assayed buffalograss leaf tissues, imidacloprid concentrations were significantly higher than those of clothianidin and thiamethoxam. Over the course of the 28 day study, thiamethoxam concentrations declined 700‐fold, whereas imidacloprid and clothianidin declined only 70‐fold and 60‐fold respectively.CONCLUSIONS: Field studies continued to verify inconsistencies in B. occiduus control with neonicotinoid insecticides. This is the first study to document the relative concentrations of topically applied neonicotinoid insecticides in buffalograss systemic leaf tissues. Copyright © 2012 Society of Chemical Industry
Genetic engineering of plant volatile terpenoids: effects on a herbivore, a predator and a parasitoid
Authors: Kos Martine , Houshyani Benyamin , Overeem Aart‐Jan , Bouwmeester Harro J , Weldegergis Berhane T , van Loon Joop JA , Dicke Marcel , Vet Louise EM 
Published: July 2012

AbstractBACKGROUND: Most insect‐resistant transgenic crops employ toxins to control pests. A novel approach is to enhance the effectiveness of natural enemies by genetic engineering of the biosynthesis of volatile organic compounds (VOCs). Before the commercialisation of such transgenic plants can be pursued, detailed fundamental studies of their effects on herbivores and their natural enemies are necessary. The linalool/nerolidol synthase gene FaNES1 was constitutively expressed from strawberry in three Arabidopsis thaliana accessions, and the behaviour of the aphid Brevicoryne brassicae L., the parasitoid Diaeretiella rapae McIntosh and the predator Episyrphus balteatus de Geer was studied.RESULTS: Transgenic FaNES1‐expressing plants emitted (E)‐nerolidol and larger amounts of (E)‐DMNT and linalool. Brevicoryne brassicae was repelled by the transgenic lines of two of the accessions, whereas its performance was not affected. Diaeretiella rapae preferred aphid‐infested transgenic plants over aphid‐infested wild‐type plants for two of the accessions. In contrast, female E. balteatus predators did not differentiate between aphid‐infested transgenic or wild‐type plants.CONCLUSION: The results indicate that the genetic engineering of plants to modify their emission of VOCs holds considerable promise for facilitating biological control of herbivores. Validation for crop plants is a necessary next step to assess the usefulness of modified volatile emission in integrated pest management. Copyright © 2012 Society of Chemical Industry
Scanning tunneling microscopy and density functional theory combined studies of rutile TiO2(1 1 0) surface chemistry: Watch surface processes at the atomic scale
Authors: Zhang Wenhua , Li Zhenyu , Wang Bing , Yang Jinlong 
Published: July 2012

AbstractTiO2 has attracted great interest in chemical and physical sciences, partially due to its potential applications in catalysis. This article provides a brief review on recent progresses of joint scanning tunneling microscopy and density functional theory investigations on the electronic structure of reduced rutile TiO2(1 1 0) surface and the adsorption and reaction of oxygen, carbon monoxide, carbon dioxide, methanol, and ethanol on the surface. © 2012 Wiley Periodicals, Inc.
The analysis of polarization effects on the interelectronic separations in the atoms and molecules of the G1 test set
Authors: Proud Adam J. , Walker Michael P. , Pearson Jason K. 
Published: July 2012

AbstractWe have calculated the differences between kinetic, nuclear attraction, and two‐electron energies as well as the position intracules, P(u), for 56 molecules and 17 atoms contained in the G1 test set, using basis sets differing in their degree of polarization. The calculations were performed using an unrestricted Hartree–Fock wave function that was expanded using the 6‐31G, 6‐31G(d,p), 6‐31G(3d,3p), 6‐31G(3df,3pd), 6‐311G, 6‐311G(d,p), 6‐311G(3d,3p), 6‐311G(3df,3pd), 6‐311++G, 6‐311++G(d,p), 6‐311++G(3d,3p), and 6‐311++G(3df,3pd) basis sets. In addition to these Pople basis sets, the Dunning's cc‐pVDZ and cc‐pVTZ bases as well as the non‐polarized portions of these basis sets were used. We observe a consistent contraction of electron pairs (as measured by the distribution in P(u)) as the number of polarization functions is increased beyond zero in molecular systems. This contraction is related to an increase in the electron density in the internuclear bonding regions of molecules as the wave functions are polarized. We note that the increased flexibility in the polarized basis set allows for a more accurate description of the chemical bond and is energetically favorable due to an increased level of attraction to the nuclei (despite the obvious increase in electronic repulsion energy). Because of the increase in electron density in internal regions of the molecule (at the expense of electron density depletions in outer regions), the probability of observing electrons closer together (i.e., at smaller u) increases due to the relationship between P(u) and its Coulomb component, J(u). © 2012 Wiley Periodicals, Inc.
Recursion relations for the three‐electron subsidiary integral W (l, m, n; α, β, γ)
Authors: Li Chun , Wang Liming , Yan Zong‐Chao 
Published: July 2012

AbstractThe subsidiary integral W (l, m, n; α, β, γ) is a key integral that appears in the variational calculation of a three‐electron atomic system using Hylleraas coordinates. For the case where the ratio α/(α + β + γ) ∼ 1, an important special situation that may occur in the evaluation of the Bethe logarithm, existing approaches for calculating the W integral become impractical due to the problem of slow convergence. In this article, we present a computationally efficient and numerical stable method, in which the W integral can be expressed in terms of either a finite series or a finite recursion relation. Numerical tests are given. © 2012 Wiley Periodicals, Inc.
Stability and robustness of large platoons of vehicles with double‐integrator models and nearest neighbor interaction
Authors: Hao He , Barooah Prabir 
Published: July 2012

SUMMARYWe study the stability and robustness of a large platoon of vehicles, where each vehicle is modeled as a double integrator, for two decentralized control architectures: predecessor following and symmetric bidirectional. In the predecessor‐following architecture, the control action on each agent only depends on the information from its immediate front neighbor, whereas in the symmetric bidirectional architecture, it depends equally on the information from both its immediate front neighbor and back neighbor. We prove asymptotic stability of the formation for a class of nonlinear controllers with sector nonlinearity, with the linear controller as a special case. We show that the convergence rate of the predecessor‐following architecture is much faster than that of the symmetric bidirectional architecture. However, the predecessor‐following architecture suffers high algebraic growth of initial errors. We also establish scaling laws (with N) of certain H ∞  norms of the formation that measure its robustness to external disturbances for the linear case. It is shown that the robustness performance grows geometrically in N for predecessor‐following architecture but only polynomially in N for symmetric‐bidirectional architecture. Extensive numerical simulations are conducted to verify the predictions for the linear case and empirically estimate the corresponding performance metrics for a saturation‐type nonlinear controller. On the basis of the analytical and numerical results, it is seen that the symmetric bidirectional architecture outperforms the predecessor‐following architecture in all measures of performance. Within the predecessor‐following architecture, the nonlinear controller is seen to perform better in general than the linear one. A number of design guidelines are provided on the basis of these conclusions. Copyright © 2012 John Wiley & Sons, Ltd.
The power of imperfect imitation
Authors: Posen Hart E. , Lee Jeho , Yi Sangyoon 
Published: July 2012

AbstractWe examine the power and limitations of imitation. Naive intuition may hold that the efficacy of imitation would be diminished by imperfections in copying high‐performing firms. Employing a computational model, we study the dynamics of imitation when firms are subject to bounded rationality that limits their ability to copy the market leader. We find that imperfect imitation can generate unexpectedly good outcomes for follower firms—indeed, better than the outcomes achieved if they were perfect imitators. Moreover, imperfect imitation, from time to time, enables follower firms to surpass superior firms. These findings suggest there is an adaptive role to mechanisms, such as bounded rationality, that make perfect imitation difficult. Copyright © 2012 John Wiley & Sons, Ltd.
Hot topics for debate in prostate cancer: part 1
Authors: Payne Heather A. , Parker Chris , Malik Zafar 
Published: July 2012

AbstractThis report is based on a seminar held during the 8th Annual Meeting of the British Uro‐oncology Group in York last September. Hot topics for debate covered in part 1 of this article are the use of active surveillance for intermediate‐risk prostate cancer and cardiovascular risks in the hormonal management of locally advanced prostate cancer. All participants, most of whom were clinical oncologists, were invited to contribute and respond to set questions using a keypad voting system. Copyright © 2012 John Wiley & Sons
Visual Representations in Second Graders' Information Book Compositions
Authors: Coleman Julianne M. , Bradley Linda Golson , Donovan Carol A. 
Published: July 2012

AbstractThis paper describes the visuals second grade students included in their own information book compositions during a science unit on weather during which multimodal science trade books on the topic of weather were read aloud. First, the multimodal nature of the information books used in the unit are described. Second, the teacher's talk about visual representations during read alouds of books on weather is presented. And third, the children's own information books about weather topics are examined for inclusion of labeled pictorial illustrations with accompanying captions and graphical representations. These analyses reveal that 1) information book authors vary in their use of visual information, 2) some graphics may be more salient for children, and 3) children's use of pictorial illustrations and graphical representations in their own compositions seems to be impacted by both teacher attention to particular types of visual representations and immersion in information book graphics.
Epoxidized Mesua ferrea L. seed oil‐plasticized thermostable PVC and PVC‐clay nanocomposites
Authors: Das Gautam , Karak Niranjan 
Published: July 2012

AbstractThe use of vegetable‐oil‐based polymeric plasticizers with nanotechnology can create new applications for plasticized poly(vinyl chloride) (PVC). Epoxidized Mesua ferrea L. (Ceylon Ironwood) seed oil was used as a plasticizer for PVC. Further, nanocomposites were prepared through an ex‐situ technique using epoxidized‐oil‐swelled organically modified montmorillonite (5 wt%) and PVC. Notable improvement in thermal and processing characteristics of the nanocomposites was observed over those of the virgin polymer (in both unplasticized and plasticized PVC), as studied by TGA. The prepared nanocomposites were characterized by FTIR, SEM, TEM, and XRD techniques. A dramatic decrease in viscosity (7‐fold) was observed in THF for a 10% solution of epoxidized‐oil‐modified PVC compared to unplasticized PVC in THF, as measured by Brookfield viscometer. Isothermal analysis at three different temperatures (100, 150, and 200°C) reveals sufficient stability of the epoxidized oil modified PVC nanocomposites, as confirmed by gravimetric and FTIR analysis. Augmentation of thermostability and good retention of mechanical properties of the (Mesua ferrea L.)‐plasticized‐PVC/clay nanocomposites with respect to rigid PVC vouch for the utility of the former as advanced industrial materials. J. VINYL ADDIT. TECHNOL., 18:168–177, 2012. © 2012 Society of Plastics Engineers