bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flow instabilities in rheotens experiments: Analysis of the impacts of the process conditions through neural network modeling
Authors: Tronci Stefania , Coppola Salvatore , Bacchelli Fabio , Grosso Massimiliano 
Published: November 2012

AbstractFiber spinning experiments are conducted with a capillary rheometer and a Rheotens tester on linear styrene‐isoprene‐styrene copolymer samples by varying extrusion temperature and drawdown velocity in a wide range of values, also covering the occurrence of instability phenomena. Tensile stress is measured during the experiences, and the experimental time series are then analyzed by means of a new methodology. The proposed approach is based on Neural Network modeling of the time series, coupled with Principal Component Analysis postprocessing of the results. The methodology is able to identify and quantify the effects of process condition on the dynamical behavior of the system. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Synthesis, characterization, biological activity, and thermal stability of new styrenic polymer having pendant ketone and its some derivatives
Authors: Erol Ibrahim , Şahin Zehra , Özcan Levent 
Published: November 2012

AbstractA new type of styrene monomer, 1‐{4‐[(4‐vinylbenzyl)oxy]phenyl}ethanone (VBOPE), was synthesized. The oxime, phenylhydrazone, toluol‐4‐sulfonic acid hydrazone, and thiosemicarbazone (TSC) derivatives of VBOPE were prepared with hydroxylamine hydrochloride, phenylhydrazine, toluol‐4‐sulfonic acid hydrazine, and TSC hydrochloride, respectively. Radical homopolymerization of the monomers were prepared at 65°C in 1,4‐dioxane solution with benzoylperoxide as an initiator. The compounds was characterized with Fourier transform infrared and NMR techniques. The thermal properties of polymers were investigated with thermogravimetric analysis and differential scanning calorimetry. The activation energies of the thermal degradation of the polymers were calculated with the Ozawa and Kissinger method. The antibacterial and antifungal effects of the monomer and the polymer and its derivatives were also investigated on various bacteria and fungi. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Chiral and water‐soluble poly(2‐oxazoline)s
Authors: Luxenhofer Robert , Huber Stephan , Hytry Julia , Tong Jing , Kabanov Alexander V. , Jordan Rainer 
Published: November 2012

AbstractWe describe the synthesis and characterization of the first water‐soluble and chiral poly(2,4‐disubstituted‐2‐oxazoline)s. While poly(2,4‐dimethyl‐2‐oxazoline)s are water soluble up to 100 °C, aqueous solutions of poly(2‐ethyl‐4‐methly‐2‐oxazoline) exhibit a lower critical solution temperature. This is discussed in context with its constitutional isomers poly(2‐oxazoline)s and poly(2‐oxazine)s. Circular dichroism spectroscopy revealed strong Cotton effects, which are also responsive to temperature in aqueous solution. It is therefore hypothesized that structures, comparable to polyproline helices, are formed in aqueous solution. In contrast to polyproline, poly(2,4‐disubstituted‐2‐oxazoline)s are highly water soluble and therefore represent very interesting pseudo‐polypeptides that may be useful to develop responsive biomimetic biomaterials. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
Donor–acceptor‐integrated conjugated polymers based on carbazole[3,4‐c:5,6‐c]bis[1,2,5]thiadiazole with tight π–π stacking for photovoltaics
Authors: Zha Daijun , Chen Lie , Wu Feiyan , Wang Hongming , Chen Yiwang 
Published: November 2012

AbstractAn original strategy to construct a new donor–acceptor (D–A)‐integrated structure by directly imposing “pull” unit on the “push” moiety to form fused ring architecture has been developed, and poly{N‐alkyl‐carbazole[3,4‐c:5,6‐c]bis[1,2,5]thiadiazole‐alt‐thiophene} (PCBTT) with D–A‐integrated structure, in which two 1,2,5‐thiadiazole rings are fixed on carbazole in 3‐, 4‐ and 5‐, 6‐position symmetrically and thiophene is used as bridge, has been synthesized. The interaction between pull and push units has fine tuned the HOMO/LUMO energy levels, and the resulting copolymer covers the solar flux from 300 to 750 nm. The interaction between pull and push units is worth noting that due to the fused five rings inducing strong intermolecular interaction, an extremely short π–π stacking distance of 0.32 nm has been achieved for PCBTT both in powder and solid states. This is the shortest π–π stacking distance reported for conjugated polymers. Additionally, an obvious intramolecular charge transfer and energy transfer from donor units to acceptor units have been detected in this D–A integration. A moderate‐to‐high open‐circuit voltage of ∼0.7 V in PCBTT:[6,6]‐phenyl‐C61 butyric acid methyl ester (PCBM) (w/w = 1/2) solar cells is achieved due to the low‐lying HOMO energy level of PCBTT. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
Photo and electrically switchable behavior of azobenzene containing pendant bent‐core liquid crystalline polymers
Authors: Srinivasan M. Vijay , Kannan P. , Roy A. 
Published: November 2012

AbstractNew class of photo and electrically switchable azobenzene containing pendant bent‐core liquid crystalline monomers (AZBM 1, 2, and 3) and their polymers (AZBP 1, 2, and 3) are reported. The synthesized precursors, monomers, and polymers were characterized by FT‐IR, 1H, and 13C NMR spectroscopy. Thermal stability of polymers was examined by thermogravimetric analysis and revealed stable up to 260 °C. The mesophase transition of monomers and polymers are observed through polarized optical microscopy (POM) and further confirmed by differential scanning calorimetry (DSC). The electrically switching property of monomers and their polymers were studied by electro‐optical method. Among the three monomers AZBM 1, 2, and 3, AZBM 1 and 2 exhibit antiferroelectric (AF) switching and AZBM 3 exhibits ferroelectric (F) switching behavior. On the other hand, low molecular weight polymers (AZMP 1, 2, and 3) show weak AF and F switching behavior. The photo‐switching properties of bent‐core azo polymers are investigated using UV‐vis spectroscopy, trans to cis isomerization occurs around 25 s for AZBP‐1 and 30 s for AZBP‐2 and 3 in chloroform, whereas reverse processes take place around 80 and 90 s. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
Hydrophilic polyisophthalamides containing poly(ethylene oxide) side chains: Synthesis, characterization, and physical properties
Authors: Carretero Paula , Molina Serena , Sandín Ricardo , Rodríguez‐Hernández Juan , Lozano Angel E. , Abajo Javier de 
Published: November 2012

AbstractNovel polyisophthalamides containing pendent poly(ethylene oxide) (PEO) sequences were prepared by grafting PEO onto poly(5‐hydroxy‐isophthalamide)s (HO‐PIPAs). First, an optimized method of synthesis was applied to prepare HO‐PIPAs, following the rules of the direct polyamidation reaction promoted by triphenyl phosphite and catalyzed by pyridine. Next, the modification of HO‐PIPAs was performed by a nucleophilic substitution reaction with chlorine‐terminated PEO monomethyl ether of average molecular weight 100, 550, and 1000 g/mol. The modification (grafting) reaction was optimized to assure virtually 100% yield. Polymers behaved as graft or brush‐like copolymers of polyisophthalamide (PIPA) and PEO, covering a wide range of ratios of PIPA/PEO. Physical properties, such as solubility, glass transition temperature, and thermal resistance were determined. Special attention was paid to the affinity of the novel copolymers for water. It was realized that with a high content of PEO, the materials could absorb water in amounts exceeding their own weight. Gravimetric methods and water contact angle measurements were used to quantify the hydrophilicity of the current PIPA‐g‐PEO copolymers. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
Introducing a new triazoloquinoxaline‐based fluorene copolymer for organic photovoltaics: Synthesis, characterization, and photovoltaic properties
Authors: Baran Derya , Pasker Felix M. , Blanc Stephan Le , Schnakenburg Gregor , Ameri Tayebeh , Höger Sigurd , Brabec Christoph J. 
Published: November 2012

AbstractA new donor‐acceptor copolymer consisting of triazoloquinoxaline and 9,9‐dialkylfluorene units on the main chain has been synthesized, characterized and evaluated as donor material in bulk heterojunction solar cells using PC61BM as an acceptor. The resulting polymer PTQF showed good thermal stability and solubility in common organic solvents. Cyclic Voltammetry measurements showed that the PTQF has HOMO–LUMO energy levels of −5.13 and −3.62 eV, respectively. DFT calculations revealed that the HOMO is delocalized all over the thiophene and fluorene units and the LUMO is localized mainly on the triazole and pyrazine units. PTQF absorbs broadly in the visible region and exhibits a bandgap of 1.4 eV. Photovoltaic devices exhibited 1.7% efficiency for 1:2 PTQF:PC61BM blend ratio using Ca/Ag electrodes. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
Photocaged pendent thiol polymer brush surfaces for postpolymerization modifications via thiol‐click chemistry
Authors: Hensarling Ryan M. , Hoff Emily A. , LeBlanc Arthur P. , Guo Wei , Rahane Santosh B. , Patton Derek L. 
Published: November 2012

AbstractIn this work, a postpolymerization surface modification approach is reported that provides pendent thiol functionality along the polymer brush backbone using the photolabile protection chemistry of both o‐nitrobenzyl and p‐methoxyphenacyl thioethers. Poly(2‐hydroxyethyl methacrylate) (pHEMA) brushes were synthesized via surface‐initiated atom transfer radical polymerization, after which the pHEMA hydroxyl groups were esterified with 3‐(2‐nitrobenzylthio)propanoic acid or 3‐(2‐(4‐methoxyphenyl)‐2‐oxoethylthio)propanoic acid to provide the photolabile protected pendent thiols. Addressing the protecting groups with light not only affords spatial control of reactive thiol functionality but enables a plethora of thiol‐mediated transformations with isocyanates and maleimides providing a modular route to create functional polymer surfaces. This concept was extended to block copolymer brush architectures enabling the modification of the chemical functionality of both the inner and outer blocks of the block copolymer surface. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
Flexible active matrix addressed displays manufactured by printing and coating techniques
Authors: Kawahara Jun , Andersson Ersman Peter , Nilsson David , Katoh Kazuya , Nakata Yasukazu , Sandberg Mats , Nilsson Marie , Gustafsson Göran , Berggren Magnus 
Published: November 2012

AbstractA flexible electrochromic active matrix addressed display, including 8 × 8 pixels, is demonstrated by using solution processing based on standard printing and coating manufacturing techniques. Each organic electrochromic display (OECD) pixel and its corresponding organic electrochemical transistor (OECT) are located on different sides of the flexible PET substrate. Electronic vias generated through the plastic substrate connects each OECD pixel with one addressing OECT. When comparing this display with actively addressed OECDs with all its components located on the same side, the present approach based on this electronic via substrate provides an enhanced pixel resolution and a relatively more simplified manufacturing process. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012
Comparison of two types of vertically aligned ZnO NRs for highly efficient polymer solar cells
Authors: Gonzalez‐Valls Irene , Angmo Dechan , Gevorgyan Suren A. , Sebastián Reparaz Juan , Krebs Frederik C. , Lira‐Cantu Monica 
Published: November 2012

AbstractVertically aligned ZnO nanorods (NR) are prepared by two different syntheses methods and applied on polymer solar cells (PSCs). The ZnO electrodes work as the electron transport layer with the P3HT:PCBM blend acting as the active material. Several organic blend solution conditions are optimized: concentration, solvent, and deposition speed. The effect of different NR electrode morphologies is analyzed on the solar cell performance and characterized by current–voltage curves and IPCE analyses. The photovoltaic performance of the solar cells was observed to be influenced by many factors, among them infiltration of the organic P3HT:PCBM blend within the ZnO NR layer. The infiltration of the active layer was monitored by cross section SEM and energy dispersive X‐ray spectroscopy analyses. Our results show that higher power conversion efficiencies are achieved when shorter NRs lengths are applied. The best power conversion efficiency obtained was 2.0% for a 400 nm ZnO NR electrode. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013
Monte‐carlo simulations of the order–disorder transition depression in ABA triblock copolymers with a short terminal block
Authors: Woloszczuk S. , Banaszak M. , Spontak R. J. 
Published: November 2012

AbstractAlthough most ABA triblock copolymers are molecularly symmetric (i.e., the terminal blocks possess the same mass), molecularly asymmetric A1BA2 triblock copolymers are of greater fundamental interest in that they can be used to explore the transition from diblock to triblock copolymer in systematic fashion. In this study, we use a lattice Monte Carlo method known as the cooperative motion algorithm to simulate molten ABA triblock copolymers possessing a short terminal block to explore the effect of molecular asymmetry on the copolymer order–disorder transition (ODT). Reduced ODT temperatures, discerned by simultaneously analyzing several features of the simulation results, are found to compare favorably with experimental data. Of particular interest here is the initial depression in the ODT temperature for A1BA2 copolymers possessing a relatively short terminal (A2) block. This signature feature is successfully captured by the simulations and is found to be strongly dependent on composition, but weakly dependent on copolymer chain length. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013
Polyvinylidene fluoride‐co‐chlorotrifluoroethylene and polyvinylidene fluoride‐co‐hexafluoropropylene nanofiber‐coated polypropylene microporous battery separator membranes
Authors: Lee Hun , Alcoutlabi Mataz , Watson Jill V. , Zhang Xiangwu 
Published: November 2012

AbstractNanofiber‐coated polypropylene (PP) separator membranes were prepared by coating a Celgard® microporous PP membrane with electrospun polyvinylidene fluoride‐co‐chlorotrifluoroethylene (PVDF‐co‐CTFE) and PVDF‐co‐CTFE/polyvinylidene fluoride‐co‐hexafluoropropylene (PVDF‐co‐HFP) nanofibers. Three PVDF polymer solutions of varying compositions were used in the preparation of the nanofiber coatings. Two of the polymer solutions were PVDF‐co‐CTFE blends made using different types of PVDF‐co‐HFP copolymers. The PVDF‐co‐CTFE and PVDF‐co‐CTFE/PVDF‐co‐HFP blend nanofiber coatings have been found to have comparable adhesion to the PP microporous membrane substrate. The electrolyte uptakes and separator–electrode adhesion properties of nanofiber‐coated membranes were evaluated. Both the electrolyte uptake and the separator–electrode adhesion were improved by the nanofiber coatings. The improvement in electrolyte update capacity is not only related to the gelation capability of the PVDF copolymer nanofibers, but also attributed to the increased porosity and capillary effect on nanofibrous structure of the electrospun nanofiber coatings. Enhancement of the separator–electrode adhesion was owing to the adhesion properties of the copolymer nanofiber coatings. Compared with the PVDF‐co‐CTFE/PVDF‐co‐HFP blend nanofiber coatings studied, the PVDF‐co‐CTFE coating was more effective in improving the electrolyte uptake and separator–electrode adhesion. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013
Life‐Cycle Assessment of Ammunition Demilitarization in a Static Kiln
Authors: Ferreira Carlos , Ribeiro José , Mendes Ricardo , Freire Fausto 
Published: November 2012

AbstractThe demilitarization of ammunition that has reached the end of life (or become obsolete) has to be carried out with minimum energy and environmental impacts. The Portuguese Armed Forces have significant amounts of ammunition that need to be eliminated. In order to assess and improve ammunition demilitarization, a life‐cycle approach must be adopted. The main goal of this article is to present a comprehensive life‐cycle assessment (LCA) of the ammunition demilitarization performed by the Portuguese company IDD (Industria de Desmilitarização e Defesa). A life‐cycle model was developed for the entire demilitarization process, which involves ammunition dismantling, discharging, the incineration of energetic material, and the subsequent flue gas treatment. A detailed inventory was based on data collected from the IDD. A life‐cycle impact assessment was carried out, based on three complementary methods used to assess a total of ten impact categories: cumulative energy demand (primary energy); CML 2001 (six environmental impact categories) and USEtox (three toxicological categories). The results show that the main contributor in nine out of the ten impact categories is the incineration and gas treatment process, due to the high energy requirements (electricity and propane). Nevertheless, equipment manufacture also has a significant impact in the Human Toxicity (non‐cancer) category, mainly related to the manufacture of the static kiln. These findings enhance our understanding of demilitarization using a static kiln, showing that the associated impacts are significant and should be reduced.
Structural Characterization of RDX‐Based Explosive Nanocomposites
Authors: Stepanov Victor , Willey Trevor M. , Ilavsky Jan , Gelb Jeff , Qiu Hongwei 
Published: November 2012

AbstractRecently developed cyclotrimethylene trinitramine (RDX)‐based nanostructured explosive compositions were shown to exhibit greatly reduced initiation sensitivity as compared to conventional compositions prepared with coarser, micrometer‐scale RDX. In particular, improvements were shown in the sensitivity towards shock and impact stimuli, key sources of inadvertent initiation. Such an improved response to mechanical stimuli is believed to be largely a result of smaller crystal and void sizes. Characterization of these structural parameters is therefore necessary in order to construct a meaningful physical description of these novel explosive compositions. Herein, we report the results of a detailed structural characterization of these novel RDX‐based nanocomposites. The analyzed specimens were in pellet form with nominally 10 % porosity. These results constitute an unprecedentedly complete structural picture of this new class of energetic materials.
Bioimpedance for Oedema Evaluation after Total Knee Arthroplasty
Authors: Pichonnaz Claude , Bassin Jean‐Philippe , Currat Damien , Martin Estelle , Jolles Brigitte M. 
Published: November 2012

AbstractBackground and PurposeElectrical bioimpedance spectroscopy (BIS) allows the evaluation of limb extracellular fluid (R0) and total fluid (Rinf). BIS could facilitate post‐surgical oedema evaluation after total knee arthroplasty (TKA), as it is easily performed and is non‐invasive. However, neither its applicability in this context nor the influence of metallic implants on measurement has been evaluated. The aim of this study was to evaluate the influence of TKA implants on the BIS R0 and Rinf variables used for oedema evaluation.MethodThis was a prospective non‐randomized comparative clinical trial. One oedema‐free group of patients with TKA was compared with a group presenting similar characteristics except for the arthroplasty, to assess the influence of the implant on BIS measurement in the absence of oedema. The TKA group included 15 patients who had undergone surgery more than a year previously, and the control group included 19 patients awaiting TKA surgery. Volume and perimeter measurements served as reference criterions. The lower limb percentage differences for BIS, knee perimeter and volume were calculated. The significance of differences between groups was calculated for all measurement methods, using the Mann–Whitney test. The setting was a Department of Orthopedic Surgery and Traumatology in a university hospital.ResultsThe differences between groups were not significant for R0, Rinf, volume and perimeter. R0 showed the smallest mean difference in limb percentage difference between groups [means (SD): TKA 3.98 (8.09), controls 3.97 (5.16)].ConclusionsThe lower‐leg percentage difference in the TKA group is comparable with that of healthy subjects. R0 can be used for oedema evaluation following TKA surgery, as there was no sign of alteration from the metallic implant. These findings indicate the potential for early oedema evaluation after TKA. More research is warranted to extensively validate the application of BIS for oedema evaluation after TKA. Copyright © 2012 John Wiley & Sons, Ltd.
Molecular basis for dramatic changes in cannabinoid CB1 G protein‐coupled receptor activation upon single and double point mutations
Authors: Scott Caitlin E. , Abrol Ravinder , Ahn Kwang H. , Kendall Debra A. , Goddard William A. 
Published: November 2012

AbstractThere is considerable interest in determining the activation mechanism of G protein‐coupled receptors (GPCRs), one of the most important types of proteins for intercellular signaling. Recently, it was demonstrated for the cannabinoid CB1 GPCR, that a single mutation T210A could make CB1 completely inactive whereas T210I makes it essentially constitutively active. To obtain an understanding of this dramatic dependence of activity on mutation, we used first‐principles‐based methods to predict the ensemble of low‐energy seven‐helix conformations for the wild‐type (WT) and mutants (T210A and T210I). We find that the transmembrane (TM) helix packings depend markedly on these mutations, leading for T210A to both TM3+TM6 and TM2+TM6 salt‐bridge couplings in the cytoplasmic face that explains the inactivity of this mutant. In contrast T210I has no such couplings across the receptor explaining the ease in activating this mutant. WT has just the TM3+TM6 coupling, known to be broken upon GPCR activation. To test this hypothesis on activity, we predicted double mutants that would convert the inactive mutant to normal activity and then confirmed this experimentally. This CB1 activation mechanism, or one similar to it, is expected to play a role in other constitutively active GPCRs as well.