bluuebunny/crossref_metadata_2025 huggingface dataset:
Bearing strength of pin‐connected polymer composites subjected to dynamic loading
Authors: Yilmaz Taner , Sinmazcelik Tamer
Published: March 2009

In this study, static load bearing strength of pin‐connected carbon fiber‐reinforced polyphenylenesulphide (PPS) composites that have [(0°/90°)]3s stacking sequence was investigated. Firstly, the samples were loaded dynamically, and then the same samples were loaded statically. The results obtained from this sequential experiment were compared with the results obtained from samples that were loaded only statically. In addition, the fatigue life and failure mechanisms were investigated with respect to the selection of the geometrical parameters. Dynamic and static loading experiments were performed according to the ASTM STP 749 and ASTM D953 standards, respectively. To obtain optimum load bearing values, the ratio of distance between the edge and hole center to hole diameter (E/D) and ratio of sample width to hole diameter (W/D) has been systematically changed. According to the experimental results, maximum load bearing values have been obtained when E/D ratio was equal to 2. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Study on superabsorbent composite XXV. Synthesis, characterization, and swelling behaviors of poly(acrylic acid‐co‐N‐acryloylmorpholine)/attapulgite superabsorbent composites
Authors: Zhang Junping , Liu Yin , Wang Aiqin
Published: March 2009

In this work, a novel poly(acrylic acid‐co‐N‐acryloylmorpholine)/attapulgite superabsorbent composite was prepared by graft copolymerization among acrylic acid, N‐acryloylmorpholine and attapulgite in aqueous solution, using N,N′‐methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. The result from FTIR spectra showed that OH of attapulgite participated in graft copolymerization with acrylic acid and N‐acryloylmorpholine. Proper monomer ratio and atapulgite content could form a loose surface, and improve reswelling ability and initial swelling rate. The buffer action of the COOH and COO− groups in the superabsorbent composite keeps the water absorbency a rough constant in the pH range of 4.4–9.6. Both polarity and structure of an organic solvent are responsible for the phase transition point of the superabsorbent composite. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Preparation, morphology, and adhesive and mechanical properties of ultrahigh‐molecular‐weight polyethylene/SiO2 nanocomposite fibers
Authors: Zhang Yi , Yu Junrong , Zhou Chengjun , Chen Lei , Hu Zuming
Published: March 2009

A simple treatment approach has been performed to achieve enhanced surface properties of ultrahigh‐molecular‐weight polyethylene (UHMWPE) fibers by incorporation of nano‐silicon dioxide (SiO2) in the presence of silane coupling agent during gel‐spinning process. The SiO2‐treated UHMWPE (UHMWPE/SiO2) nanocomposite fibers with different nano‐SiO2 compositions were characterized with Fourier transform infrared spectra, scanning electron microscopy, and wide‐angle X‐ray diffraction, and their interfacial adhesion and mechanical properties were also investigated. The nano‐SiO2 can be trapped on the surface of the fibers to form rough surface for UHMWPE/SiO2 fibers, and diffused into the inner of fibers to induce the lower crystal sizes and higher crystallinity of polyethylene in UHMWPE/SiO2 fibers. The resulting UHMWPE/SiO2 fibers therefore exhibit a dramatic enhancement in the adhesive properties because of the combination of rougher surface compared with those of UHMWPE fiber and polar groups absorbed on the surface of fibers. The mechanical properties of UHMWPE/SiO2 nanocomposite fibers are enhanced simultaneously because of the influence of nano‐SiO2 on the structure of UHMWPE crystalline regions and fibrils. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Proteomic analysis of cytoplasmic and surface proteins from yeast cells, hyphae, and biofilms of Candida albicans
Authors: Martínez‐Gomariz Montserrat , Perumal Palani , Mekala Satish , Nombela César , Chaffin W. LaJean , Gil Concha
Published: March 2009

Candida albicans is a human commensal and opportunistic pathogen that participates in biofilm formation on host surfaces and on medical devices. We used DIGE analysis to assess the cytoplasmic and non‐covalently attached cell‐surface proteins in biofilm formed on polymethylmethacrylate and planktonic yeast cells and hyphae. Of the 1490 proteins spots from cytoplasmic and 580 protein spots from the surface extracts analyzed, 265 and 108 were differentially abundant respectively (>1.5‐fold, p <0.05). Differences of both greater and lesser abundance were found between biofilms and both planktonic conditions as well as between yeast cells and hyphae. The identity of 114 cytoplasmic and 80 surface protein spots determined represented 73 and 25 unique proteins, respectively. Analyses showed that yeast cells differed most in cytoplasmic profiling while biofilms differed most in surface profiling. Several processes and functions were significantly affected by the differentially abundant cytoplasmic proteins. Particularly noted were many of the enzymes of respiratory and fermentative pentose and glucose metabolism, folate interconversions and proteins associated with oxidative and stress response functions, host response, and multi‐organism interaction. The differential abundance of cytoplasmic and surface proteins demonstrated that sessile and planktonic organisms have a unique profile.
Targeted serum glycoproteomics for the discovery of lung cancer‐associated glycosylation disorders using lectin‐coupled ProteinChip arrays
Authors: Ueda Koji , Fukase Yu , Katagiri Toyomasa , Ishikawa Nobuhisa , Irie Shinji , Sato Taka‐Aki , Ito Hiroyuki , Nakayama Haruhiko , Miyagi Yohei , Tsuchiya Eiju , Kohno Nobuoki , Shiwa Mieko , Nakamura Yusuke , Daigo Yataro
Published: March 2009

To screen for glycoproteins showing aberrant sialylation patterns in sera of cancer patients and apply such information for biomarker identification, we performed SELDI‐TOF MS analysis coupled with lectin‐coupled ProteinChip arrays (Jacalin or SNA) using sera obtained from lung cancer patients and control individuals. Our approach consisted of three processes (i) removal of 14 abundant proteins in serum, (ii) enrichment of glycoproteins with lectin‐coupled ProteinChip arrays, and (iii) SELDI‐TOF MS analysis with acidic glycoprotein‐compatible matrix. We identified 41 protein peaks showing significant differences (p<0.05) in the peak levels between the cancer and control groups using the Jacalin‐ and SNA‐ProteinChips. Among them, we identified loss of Neu5Ac (α2,6) Gal/GalNAc structure in apolipoprotein C‐III (apoC‐III) in cancer patients through subsequent MALDI‐QIT‐TOF MS/MS. Furthermore, subsequent validation experiments using an additional set of 60 lung adenocarcinoma patients and 30 normal controls demonstrated that there is a higher frequency of serum apoC‐III with loss of α2,6‐linkage Neu5Ac residues in lung cancer patients compared to controls. Our results have demonstrated that lectin‐coupled ProteinChip technology allows the high‐throughput and specific recognition of cancer‐associated aberrant glycosylations, and implied a possibility of its applicability to studies on other diseases.
Sequencing of the thirteen structurally isomeric quartets of N‐terminal dipeptide motifs in peptides by collision‐induced dissociation
Authors: Winter Dominic , Lehmann Wolf D.
Published: March 2009

N‐terminal sequencing of protonated peptides is challenging, since each b2 ion represents two sequence isomers, e.g., NE and EN. Additionally the occurrence of compositional isomers, such as NE and QD, further increases the number of isomers to four (NE, EN, QD, DQ). This leads to a subset of 13 b2 ion masses where each value represents four individual species. The b2 ions within such a quartet are characterized by the same elemental composition. To test the utility of CID for differentiation of isomeric b2 ions, the CID spectra of 52 small synthetic peptides were recorded, representing the 13 isomeric b2 ion quartets, which may be formed from unmodified amino acid residues. The CID spectra of protonated peptides containing these quartets were carefully inspected for N‐terminal sequence information. Below the m/z value of the b2 ion, individual differences were found in the b2 fragment ion signatures (neutral loss of CO, H2O, NH3, and other less common units). Recognition of N and Q in second position from the N‐terminus is based on c1 ion formation. Relative intensities of immonium ions were also used for differentiation between sequence isomers. In the complementary high‐mass regions above the m/z value of the ymax‐2 ion, individual differences were observed in the formation of ymax‐1, xmax‐1 and zmax‐1 ions, which could be correlated to the complementary low‐mass ions. In summary, de novo sequencing of the N‐terminal dipeptide motif is feasible by considering all available sequence information present in CID spectra of protonated peptides.
Exploring the priming mechanism of liver regeneration: proteins and protein complexes
Authors: Deng Xinyu , Li Wenrui , Chen Ning , Sun Yanwei , Wei Handong , Jiang Ying , He Fuchu
Published: March 2009

The liver has the ability to restore its functional capacity following injury or resection and the priming of liver regeneration is a complex process that has not been completely elucidated. In the current research, to further reveal the priming mechanism of liver regeneration, hepatocyte total protein and hepatocyte cytosol of the rats at 4 h after 2/3 partial hepatectomy (PHx) were studied, respectively, by 2‐DE and 2‐D blue native gel electrophoresis. Seventeen unique differential proteins were identified in hepatocyte total protein samples. Nine differential protein complexes containing 41 protein components were identified in hepatocyte cytosol samples. For the first time, at the priming stage of liver regeneration, the variations of serine protease inhibitor 2c, sulfite oxidase and valosin‐containing protein (VCP) were presented and validated by Western blotting, and the VCP complex was further validated by antibody super‐shift experiments. The current results suggested that at 4 h after PHx, VCP complex was down‐regulated in hepatocyte cytosol, apoptosis pathways were inhibited, nuclear factor‐κB and interleukin 6 pathways worked together and triggered the liver regeneration.
Detection of allergen specific immunoglobulins by microarrays coupled to microfluidics
Authors: Cretich Marina , Di Carlo Gabriele , Giudici Cinzia , Pokoj Sven , Lauer Iris , Scheurer Stephan , Chiari Marcella
Published: March 2009

Allergen microarrays are under development for a component‐resolved diagnosis of Type I (IgE‐mediated) allergies. Here we report an improved microarray coupled to microfluidics for the detection of allergen specific immunoglobulin E (IgE). The signal intensity for IgE detection in serum has been improved by using glass slides coated with a novel poly[DMA‐co‐NAS] brush copolymer which is able to immobilize allergens in their native conformation and by carrying out the incubation step in dynamic conditions. The assay, fully automated, was performed in a microcell, using a software‐controlled fluidic processor, to bring assay reagents on the surface of the array. Microfluidics turns the binding between serum immunoglobulins and immobilized allergens from a diffusion‐limited to a kinetic‐limited process by ensuring an efficient mixing of serum samples on the surface of the microarray. As a result of this, the binding of high affinity IgE antibodies is enhanced whereas that of low affinity IgG antibodies, which are present at higher concentration, is impaired paving the way to more accurate and sensitive results.
Proteomic changes in the crucian carp brain during exposure to anoxia
Authors: Smith Richard W. , Cash Phil , Ellefsen Stian , Nilsson Göran E.
Published: March 2009

During exposure to anoxia, the crucian carp brain is able to maintain normal overall protein synthesis rates. However, it is not known if there are alterations in the synthesis or expression of specific proteins. This investigation addresses this issue by comparing the normoxic and anoxic brain proteome. Nine proteins were found to be reduced by anoxia. Reductions in the glycolytic pathway proteins creatine kinase, fructose biphosphate aldolase, glyceraldehyde‐3‐phosphate dehydrogenase, triosephosphate isomerase and lactate dehydrogenase reflect the reduced production and requirement for adenosine tri‐phosphate during anoxia. In terms of neural protection, voltage‐dependent anion channel, a protein associated with neuronal apoptosis, was reduced, along with gefiltin, a protein associated with the subsequent need for neuronal repair. Additionally the expression of proteins associated with neural degeneration and impaired cognitive function also declined; dihydropyrimidinase‐like protein‐3 and vesicle amine transport protein‐1. One protein was found to be increased by anoxia; pre‐proependymin, the precursor to ependymin. Ependymin fulfils multiple roles in neural plasticity, memory formation and learning, neuron growth and regeneration, and is able to reverse the possibility of apoptosis, thus further protecting the anoxic brain.
Anthracene‐ and thiophene‐containing MEH‐PPE‐PPVs: Synthesis and study of the effect of the aromatic ring position on the photophysical and electrochemical properties
Authors: Wild Andreas , Egbe Daniel A. M. , Birckner Eckhard , Cimrová Vera , Baumann Reinhard , Grummt Ulrich‐Walter , Schubert Ulrich S.
Published: March 2009

This contribution reports on the synthesis and characterization of thiophene‐ (P1, P2, and P3) and anthracene‐ (P4 and P5) containing PPE‐PPV copolymers. The thermostable, soluble and film‐forming polymers were fully characterized by NMR, IR and ELEM. ANAL.; they exhibit high molar masses with polydispersity indices below 2.5. The position of the thiophene in the polymeric backbone has insignificant influence on the spectroscopic properties of the polymers. In contrast, the anthracene‐containing polymers reveal position dependent optical properties. A constant bathochromic shift of 50 nm was observed going from P4, where anthracene is surrounded by two double bonds, to P5, where anthracene is at the bridge between a triple bond and a double bond, as well as from P5 to P6 where anthracene is surrounded by two triple bonds. This correlates to the decrease of the observed anthracene band around 255 nm going from P4 through P5 to P6, amounting to the degree of contribution of the anthracene unit to the main chain conjugation. The phenomenon known as CN‐PPV effect was observed in the case of P4 [Φf (solution) = 3%, Φf (solid) = 13%]. Electrochemical studies carried out under absolute inert conditions revealed lower electrochemical band gap energies, E, than E. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2243–2261, 2009
Polybenzimidazoles tethered with N‐phenyl 1,2,4‐triazole units as polymer electrolytes for fuel cells
Authors: Potrekar R. A. , Kulkarni M. P. , Kulkarni R. A. , Vernekar S. P.
Published: March 2009

Polybenzimidazole (PBI) polymers tethered with N‐phenyl 1,2,4‐triazole (NPT) groups were prepared from a newly synthesized aromatic diacid, 3′‐(4‐phenyl‐4H‐1,2,4‐triazole‐3,5‐diyl) dibenzoic acid (PTDBA). The obtained polymers show superior thermal and chemical stability and good solubility in many aprotic solvents. The inherent viscosities of all polymers were around 1 dL/g. They exhibit high thermal stability with initial decomposition temperature ranging from 515 to 530 °C, high glass transition temperature ranging from 375 to 410 °C, and good mechanical properties with tensile stress in the range of 66–98 MPa and modulus 1897–2600 MPa. XRD analysis indicates that these polymers are amorphous in nature. Physicochemical properties such as water and phosphoric acid‐uptake, oxidative stability, and proton conductivity of membranes of these polymers have also been determined. The proton conductivity ranged from 4.7 × 10−3 to 1.8 × 10−2 S cm−1 at 175 °C in dry conditions. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2289–2303, 2009
Highly stable electrochromic polyamides based on N,N‐bis(4‐aminophenyl)‐N′,N′‐bis(4‐tert‐butylphenyl)‐1,4‐phenylenediamine
Authors: Hsiao Sheng‐Huei , Liou Guey‐Sheng , Wang Hui‐Min
Published: March 2009

A new triphenylamine‐containing aromatic diamine monomer, N,N‐bis(4‐aminophenyl)‐N′,N′‐bis(4‐tert‐butylphenyl)‐1,4‐phenylenediamine, was synthesized by an established synthetic procedure from readily available reagents. A novel family of electroactive polyamides with di‐tert‐butyl‐substituted N,N,N′,N′‐tetraphenyl‐1,4‐phenylenediamine units were prepared via the phosphorylation polyamidation reactions of the newly synthesized diamine monomer with various aromatic or aliphatic dicarboxylic acids. All the polymers were amorphous with good solubility in many organic solvents, such as N‐methyl‐2‐pyrrolidinone (NMP) and N,N‐dimethylacetamide, and could be solution‐cast into tough and flexible polymer films. The polyamides derived from aromatic dicarboxylic acids had useful levels of thermal stability, with glass‐transition temperatures of 269–296 °C, 10% weight‐loss temperatures in excess of 544 °C, and char yields at 800 °C in nitrogen higher than 62%. The dilute solutions of these polyamides in NMP exhibited strong absorption bands centered at 316–342 nm and photoluminescence maxima around 362–465 nm in the violet‐blue region. The polyamides derived from aliphatic dicarboxylic acids were optically transparent in the visible region and fluoresced with a higher quantum yield compared with those derived from aromatic dicarboxylic acids. The hole‐transporting and electrochromic properties were examined by electrochemical and spectro‐electrochemical methods. Cyclic voltammograms of the polyamide films cast onto an indium‐tin oxide‐coated glass substrate exhibited two reversible oxidation redox couples at 0.57–0.60 V and 0.95–0.98 V versus Ag/AgCl in acetonitrile solution. The polyamide films revealed excellent elcterochemical and electrochromic stability, with a color change from a colorless or pale yellowish neutral form to green and blue oxidized forms at applied potentials ranging from 0.0 to 1.2 V. These anodically coloring polymeric materials showed interesting electrochromic properties, such as high coloration efficiency (CE = 216 cm2/C for the green coloring) and high contrast ratio of optical transmittance change (ΔT%) up to 64% at 424 nm and 59% at 983 nm for the green coloration, and 90% at 778 nm for the blue coloration. The electroactivity of the polymer remains intact even after cycling 500 times between its neutral and fully oxidized states. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2330–2343, 2009
Pegylated thermally responsive block copolymer micelles and nanogels via in situ RAFT aqueous dispersion polymerization
Authors: Rieger Jutta , Grazon Chloé , Charleux Bernadette , Alaimo David , Jérôme Christine
Published: March 2009

A very straightforward approach was developed to synthesize pegylated thermoresponsive core‐shell nanoparticles in a minimum of steps, directly in water. It is based on RAFT‐controlled radical crosslinking copolymerization of N,N‐diethylacrylamide (DEAAm) and N,N′‐methylene bisacrylamide (MBA) in aqueous dispersion polymerization. Because DEAAm is water‐soluble and poly(N,N‐diethylacrylamide) (PDEAAm) exhibits a lower critical solution temperature at 32 °C, the initial medium was homogeneous, whereas the polymer formed a separate phase at the reaction temperature. The first macroRAFT agent was a surface‐active trithiocarbonate based on a hydrophilic poly(ethylene oxide) block and a hydrophobic dodecyl chain. It was further extented with N,N‐dimethylacrylamide (DMAAm) to target macroRAFT agents with increasing chain length. All macroRAFT agents provided excellent control over the aqueous dispersion homopolymerization of DEAAm. When they were used in the radical crosslinking copolymerization of DEAAm and MBA, the stability and size of the resulting gel particles were found to depend strongly on the chain length of the macroRAFT agent, on the concentrations of both the monomer and the crosslinker, and on the process (one step or two steps). The best‐suited experimental conditions to reach thermosensitive hydrogels with nanometric size and well‐defined surface properties were determined. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2373–2390, 2009
Relaxations in chitin: Evidence for a glass transition
Authors: González‐campos J. Betzabe , Prokhorov Evgen , Luna‐Bárcenas Gabriel , Galván A. Mendoza , Sanchez Isaac C. , Nuño Donlucas Sergio M. , Garcia‐Gaitan B. , Kovalenko Yuriy
Published: March 2009

Relaxations in chitin have been investigated in the temperature range 298–523 K using impedance spectroscopy in the frequency range 10−1–108 Hz. The objective was to detect a glass‐transition temperature for this naturally occurring, semicrystalline polysaccharide. The impedance study was complemented with X‐ray diffraction, thermogravimetric, and differential scanning calorimetry measurements. Preliminary impedance data treatment includes the subtraction of the dc conductivity contribution, the exclusion of contact and interfacial polarization effects, and obtaining a condition of minimum moisture content for further analysis. When all these aspects are taken into account, two relaxations are clearly revealed in the impedance data. For the first time, evidence is presented for a relaxation process, which exhibits a non‐Arrhenius temperature dependence, in dry α‐chitin (∼0.1% moisture content), and likely represents the primary α‐relaxation. This evidence suggests a glass transition temperature for chitin of 335 ± 10 K estimated on the basis of the temperature dependence of the conductivity and of the relaxation time. A second relaxation in dry α‐chitin, not previously reported in the literature, is observed from 353 K to the onset of thermal degradation (∼483 K) and is identified as the σ‐relaxation often associated with proton mobility. It exhibits a normal Arrhenius‐type temperature dependence with activation energy of 113 ± 3 kJ/mol. The latter has not been previously reported in the literature. A high frequency secondary β‐relaxation is also observed with Arrhenius activation energy of 45 ± 1 kJ/mol. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 932–943, 2009
Application of a crystallization kinetics model to simulate the effect of operation conditions on Crystaf profiles and calibration curves
Authors: Anantawaraskul Siripon , Somnukguandee Punnawit , Soares João B. P. , Limtrakul Jumras
Published: March 2009

Crystallization analysis fractionation (Crystaf) is a polymer characterization technique used to estimate chemical composition distributions (CCDs) of semicrystalline copolymers. The Crystaf profile can be transformed into a CCD using a calibration curve that relates average comonomer content to peak crystallization temperature. The calibration curve depends on copolymer molecular properties and Crystaf operation conditions. In this investigation, we applied a crystallization kinetics model to simulate Crystaf calibration curves and to quantify how Crystaf calibration curves depend on these factors. We applied the model to estimate the CCDs of three ethylene/1‐hexene copolymers from Crystaf profiles measured at different cooling rates and showed that our predictions agree well with the CCDs described by Stockmayer's distribution. We have also used this new methodology to investigate the effects of cooling rate, molecular weight, and comonomer type on Crystaf profiles and calibration curves. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 866–876, 2009
Functionalized graphene sheet—Poly(vinylidene fluoride) conductive nanocomposites
Authors: Ansari Seema , Giannelis Emmanuel P.
Published: March 2009

PVDF nanocomposites based on functionalized graphene sheets, FGS prepared from graphite oxide, and exfoliated graphite, EG, were prepared by solution processing and compression molding. FGS remains well dispersed in the PVDF composites as evidenced by the lack of the characteristic graphite reflection in the composites. Although the α‐phase of PVDF is seen in the EG‐based composites, a mixture of α‐ and β‐phases is present in the FGS analogs. SEM and TEM imaging show smooth fractured surfaces with oriented platelets of graphite stacks and obvious debonding from the matrix in the EG‐PVDF composites. In contrast, the FGS‐PVDF composites show a wrinkled topography of relatively thin graphene sheets bonded well to the matrix. Storage modulus of the composites was increased with FGS and EG concentration. A lower percolation threshold (2 wt %) was obtained for FGS‐PVDF composites compared to EG‐PVDF composites (above 5 wt %). Lastly, the FGS‐PVDF composites show an unusual resistance/temperature behavior. The resistance decreases with temperature, indicating an NTC behavior, whereas EG‐PVDF composites show a PTC behavior (e.g., the resistance increases with temperature). We attribute the NTC behavior of the FGS based composites to the higher aspect ratio of FGS which leads to contact resistance predominating over tunneling resistance. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 888–897, 2009
The effect of the cosolvent trifluoroethanol on a tryptophan side chain orientation in the hydrophobic core of troponin C
Authors: Julien Olivier , Mercier Pascal , Crane Melissa L. , Sykes Brian D.
Published: March 2009

The unique biophysical properties of tryptophan residues have been exploited for decades to monitor protein structure and dynamics using a variety of spectroscopic techniques, such as fluorescence and nuclear magnetic resonance (NMR). We recently designed a tryptophan mutant in the regulatory N‐domain of cardiac troponin C (F77W‐cNTnC) to study the domain orientation of troponin C in muscle fibers using solid‐state NMR. In our previous study, we determined the NMR structure of calcium‐saturated mutant F77W‐V82A‐cNTnC in the presence of 19% 2,2,2‐trifluoroethanol (TFE). TFE is a widely used cosolvent in the biophysical characterization of the solution structures of peptides and proteins. It is generally assumed that the structures are unchanged in the presence of cosolvents at relatively low concentrations, and this has been verified for TFE at the level of the overall secondary and tertiary structure for several calcium regulatory proteins. Here, we present the NMR solution structure of the calcium saturated F77W‐cNTnC in presence of its biological binding partner troponin I peptide (cTnI144–163) and in the absence of TFE. We have also characterized a panel of six F77W‐cNTnC structures in the presence and absence TFE, cTnI144–163, and the extra mutation V82A, and used 19F NMR to characterize the effect of TFE on the F77(5fW) analog. Our results show that although TFE did not perturb the overall protein structure, TFE did induce a change in the orientation of the indole ring of the buried tryptophan side chain from the anticipated position based upon homology with other proteins, highlighting the potential dangers of the use of cosolvents.
High‐performance UV emitter grown on high‐crystalline‐quality AlGaN underlying layer
Authors: Tsuzuki Hirotoshi , Mori Fumiaki , Takeda Kenichiro , Ichikawa Tomoki , Iwaya Motoaki , Kamiyama Satoshi , Amano Hiroshi , Akasaki Isamu , Yoshida Harumasa , Kuwabara Masakazu , Yamashita Yoji , Kan Hirofumi
Published: March 2009

Al0.25Ga0.75N films were grown on a grooved‐Al0.25Ga0.75N/ AlN/sapphire template by MOVPE. The dislocation density on the grooved areas was as low as 1 × 108 cm–2. We fabricated a UVA light‐emitting diode grown on such an AlGaN underlying layer exhibiting an output power of 12 mW at a DC current of 50 mA with a peak emission wavelength of 345 nm, which corresponds to an external quantum efficiency of 6.7%. This efficiency is the highest reported to date in this wavelength region. We also fabricated a 358 nm UVA laser diode (LD) using a GaN/AlGaN MQW active layer grown on an AlGaN underlying layer. This UV LD exhibits a threshold current of 73 mA and a corresponding current density of 3.8 kA/cm2 at 7 °C. The characteristic temperature T0 was 174 K in the temperature range of 7–27 °C. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrochemically induced bioactivity of porous silicon functionalized by acetylene
Authors: Pastor Ester , Salonen Jarno , Lehto Vesa‐Pekka , Matveeva Eugenia
Published: March 2009

In order to improve the bioactivity of porous silicon chemically functionalized by acetylene (PSi–C) and stimulate the calcium‐phosphorous (hydroxyapatite) deposition on this material from a simulated body fluid, electrochemical oxidation of the PSi–C templates has been employed. The initial functionalization by acetylene was done at 500 °C in a N2 + C2H2 gas stream of 1:1 ratio for 15 minutes; further electrochemical oxidation was performed in 80% phosphoric acid. The morphology and chemical composition of initial and oxidized porous structures were studied by the high resolution SEM technique and FTIR spectroscopy. Initial chemical functionalization leads to a very stable (practically bio‐inert) material that after electrochemical oxidation becomes bioactive. We observed that the hydroxyapatite phase has been homogeneously deposited on the electrochemically oxidized PSi–C material immersed in the SBF of Kokubo formulae at 36.5 °C just after two weeks. The layer of hydroxyapatite grown on the surface after 30 days of immersion was compact, crystalline and as thick as 5 μm. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Detection of protease activity by FRET using porous silicon as an energy acceptor
Authors: Gu Luo , Orosco Manuel , Sailor Michael J.
Published: March 2009

This work demonstrates a method for detection of protease activity using porous Si as the energy acceptor in a Fluorescence Resonance Energy Transfer (FRET) assay. A fluorescent dye (fluorescein) is trapped in a porous Si matrix, where its fluorescence is quenched. The dye is trapped using a protein (zein), and the action of proteases (Pronase E) release the dye from the quenching matrix. A strong fluorescence signal appears within 30 min of Pronase E addition. A control with no Pronase E shows little fluorescence, and a control using heat‐denatured Pronase E shows approximately 50% of the fluorescence of the active protease. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
In‐situ investigation of the structural phase transition in kesterite
Authors: Schorr Susan , Gonzalez‐Aviles Gabriela
Published: March 2009

A polycrystalline Cu2ZnSnS4 sample (kesterite) was investigated by in‐situ high temperature diffraction using synchrotron X‐rays, revealing for the first time a structural phase transition from the tetragonal kesterite type structure (space group I$ \bar 4 $2m) to the cubic sphalerite type structure (space group F$ \bar 4 $3m). Within 866–883 °C a phase transition region occurs, were a tetragonal phase and a cubic phase coexists. Outside the phase transition region, the lattice parameter of the tetragonal phase increase nearly linearly with increasing temperature, whereas the lattice parameter of the cubic phase show first a negative thermal expansion changing at ∼930 °C to a further linear increase of acub. A cation anti‐site occupancy can only be observed within the phase transition region. On the other hand, the anion position parameters x and z change, which starts at ∼150 °C and lasts up to the phase transition region. Both atomic position parameters reach nearly the ideal value of 1/4, indicating the anion in the middle of the cation tetrahedra. Thus the structural phase transition in Cu2ZnSnS4 from the tetragonal kesterite type to the cubic sphalerite type structure is characterized much more by a displacive behaviour of the anion substructure then by an anti‐site occupancy of the cation substructure. Because the space group I$ \bar 4 $2m) is not a subgroup of I$ \bar 4 $2d) and a group‐subgroup relation is mandatory for displacive phase transitions, the non‐existence of a I$ \bar 4 $2m) → I$ \bar 4 $2d) transition seems plausible. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
UV photoreflectance spectroscopy in strained silicon on insulator structures
Authors: Munguía Jacobo , Bluet Jean‐Marie , Chouaib Houssam , Bremond Georges , Bru‐Chevallier Catherine
Published: March 2009

The optical modulation technique of photoreflectance (PR) is applied on tensely‐strained silicon on insulator (sSOI) substrates in order to determine the deformation potential in the strained silicon direct band gap. Raman spectroscopy is used for strain determination. A redshift of the Si direct band gap transition is observed as the strain induced in the layer is increased. We report a band gap shrinkage at Γ‐point down to 60 ± 6 meV, 120 ± 15 meV and 127 ± 13 meV for 0.77 ± 0.02%, 1.22 ± 0.02% and 1.40 ± 0.03% of strain, respectively. The obtained deformation potential in the direct band gap (a = –0.55 eV and b = –2.45 eV) are in good agreement with previously reported results for bulk material. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Critical diameters and temperature domains for MBE growth of III–V nanowires on lattice mismatched substrates
Authors: Cirlin G. E. , Dubrovskii V. G. , Soshnikov I. P. , Sibirev N. V. , Samsonenko Yu. B. , Bouravleuv A. D. , Harmand J. C. , Glas F.
Published: March 2009

We report on the growth properties of InAs, InP and GaAs nanowires (NWs) on different lattice mismatched substrates, in particular, on Si(111), during Au‐assisted molecular beam epitaxy (MBE). We show that the critical diameter for the epitaxial growth of dislocation‐free III–V NWs decreases as the lattice mismatch increases and equals 24 nm for InAs NWs on Si(111), 39 nm for InP NWs on Si(111), 44 nm for InAs NWs on GaAs(111)B, and 110 nm for GaAs NWs on Si(111). When the diameters exceed these critical values, the NWs are dislocated or do not grow at all. The corresponding temperature domains for NW growth extend from 320 °C to 340 °C for InAs NWs on Si(111), 330 °C to 360 °C for InP NWs on Si(111), 370 °C to 420 °C for InAs NWs on GaAs(111)B and 380 °C to 540 °C for GaAs NWs on Si(111). Experimental values for critical diameters are compared to the previous findings and are discussed within the frame of a theoretical model. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Toward a More Realistic QSAR Approach to Predicting Metal Toxicity
Authors: Lepădatu Costinel , Enache Monica , Walker John D.
Published: March 2009

The subject of this paper is to present molecular descriptors representing the electronegativity of OMO (occupied molecular orbital) and UMO (unoccupied molecular orbital) quantum molecular states that could be used to obtain information on the mechanism of electron transfer between metal compound and biological receptor. The molecular descriptors that were used suggested that the (s,p) and (dN) metal ions have different mechanisms of interaction with the receptor. This result explains why the correlation activity–descriptor is rather poor or practically does not exist when all metal ions are analyzed together (irrespective of their valence shell). Since this interaction is the last event of the long chain of processes of the metal ion up to the biological target, such molecular descriptors could be used together with other descriptors in QSAR models for prediction of biological activity.
Protection of bridge piers against ship collision
Authors: Svensson Holger
Published: March 2009

This article outlines the development of pier protection against ship collision over the last 25 years. The calculation of impact forces is developed from general formulas for equivalent loads, based on collision tests, to numerical FEM simulations. Comparisons between the results are given. Examples of the structural protection of 18 bridges are described.
Composite beam composed of steel and precast concrete (modularized hybrid system). Part IV: Application for multi‐residential housing
Authors: Hong Won‐Kee , Kim Seung‐Il , Park Seon‐Chee , Kim Jin‐Min , Lee Seung‐Geun , Yoon Ki‐Joon , Kim Sun‐Kuk
Published: March 2009

Multi‐residential bearing wall apartments have been constructed to meet the needs of the population growth in metropolitan Korea since 1980. It is extremely difficult to remodel wall‐type multi‐residential apartments due to the nature of the bearing walls. Residents also experience noise and vibrations generated between floors. It is necessary to introduce a frame structure that enables easy remodelling for the realization of long life of apartment. This paper introduces an efficient, multi‐residential modularized hybrid system (MHS). The material quantities, material cost and amount of CO2 emission for the MHS are compared to that of bearing wall structures (linear rectangular shape and tower shape) and flat slab structures. A multi‐residential apartment with an MHS composite girder ensures architectural plan flexibility and easy remodelling, while the floor heights are maintained at the same floor height as in bearing wall structures. The material cost of MHS multi‐residential housing can be reduced by reducing the amount of concrete and reinforcement steels required for the slabs and walls. The MHS also reduces CO2 emission in accordance with the reduction of construction materials. Dry‐type construction can be environment friendly by reducing human resources, temporary materials and waste. Copyright © 2009 John Wiley & Sons, Ltd.
Practical modelling of high‐rise dual systems with reinforced concrete slab‐column frames
Authors: Shin Myoungsu , Kang Thomas H.‐K. , Grossman Jacob S.
Published: March 2009

This paper discusses practical modelling issues pertinent to the design of an irregularly shaped reinforced concrete (RC) high‐rise building currently under development in New York City. The structure analysed consists of a 60‐storey residential tower and a 25‐storey hotel building structurally connected to each other. For the seismic force resistance, a dual system combining ordinary RC shear walls and intermediate slab–column moment frames was used at the upper portion, while a building frame system of ordinary RC shear walls was used at the lower portion of the structure. A variety of models were used to simulate the behaviour of various elements of the structure, with special attention given to overall systemic effects of different member stiffnesses considered to account for distinct stress levels under service and ultimate loads. The models used for slab–column frames and shear walls were verified by comparing with other available models or laboratory tests. The in‐plane flexibility of floor diaphragms at the interface between the two substructures with different geometries was simulated to identify the most critical wind conditions for each structural member. Finally, building dynamic analyses were performed to demonstrate the modelling issues to be considered for the lateral force design of irregular high‐rise buildings. Copyright © 2009 John Wiley & Sons, Ltd.
Progressive collapse resisting capacity of tube‐type structures
Authors: Kim Jinkoo , Lee Young‐Ho
Published: March 2009

In this study, the progressive collapse potential of tube‐type buildings, such as diagrid and tubular structures, composed of lateral load‐resisting perimeter frames and internal pin‐connected gravity frames, was evaluated by nonlinear static and dynamic analyses. To this end, 36‐ and 54‐storey structures were designed as analysis models and progressive collapse analyses were carried out by removing first‐storey columns. According to the analysis results, the progressive collapse of tube‐type analysis model buildings occurred when perimeter columns corresponding to more than 11% of all member cross‐sectional areas were removed from one side of the structures. When the diagonals located around a corner were removed, the ratio was reduced to 8%. It was observed that the corner columns in the diagrid system helped prevent the propagation of member failure all around the perimeter. Copyright © 2009 John Wiley & Sons, Ltd.
Simply too complicated
Authors: Tedeschi Riccardo
Published: March 2009

Starting from the late 1990s and in the first years of the new century, the business of credit securitization has known incredible development, but the credit crunch triggered in August 2007 by American sub‐prime residential mortgages has probably cut to the heart of the so‐called “warehouse and sell” model of business. As a contribution to a higher level of transparency in the business of securitization, this paper tries to give an answer to the question “why is it so difficult to evaluate ABSs and CDOs?” In brief, one might say that “it is not a matter of financial models”. The problem is that ABS and CDO contracts are often too complicated, and there is a significant level of uncertainty concerning the key parameters that characterize the credit portfolios sold by securitization (default probabilities, recovery rates, default correlation), coupled with a strong sensitivity of the CDO prices to the variations of these parameters. At the moment we do not know if ABSs and CDOs will ever have a future, but we know for sure that, to survive, the securitization business will have to change. Hopefully, this crisis will probably bring some benefit in the coming years, probably because it will force big international banks to move toward simpler structures, more secure standards in the selection of borrowers, and a higher level of openness about economic information. If this does happen, we will hopefully remember the events of September and October 2008 as a kind of “adolescent crisis” that led to a more mature market. But for this to happen it is essential that investors learn to apply a few “commonsense” rules in the asset selection process and do not forget to estimate their own fair values and perform their own stress tests when they decide to put their money into these kind of products. Copyright © 2009 Wilmott Magazine Ltd
To the Knowledge of Interpseudohalogens: A Contribution to Cyanogen Isocyanate (NC–NCO)
Authors: Schmidt Carsten L. , Fischer Dieter , Himmel Hans‐Jörg , Köppe Ralf , Schnöckel Hansgeorg , Jansen Martin
Published: March 2009

Cyanogen isocyanate (NC–NCO) has been prepared and studied using a combined experimental and theoretical approach. A crystalline film of the interpseudohalogen species was stabilized by vapor deposition on a cold substrate (T = –100 °C). From IR spectroscopy on the “free” molecule, trapped in a matrix of solid argon, the connectivity and geometry of this unstable interpseudohalogen was deduced and substantiated by theoretical calculations. With this information, the crystal structure of NCNCO in the solid state could be analysed using powder X‐ray diffraction [Pbca (No. 61), a = 7.63(1) Å, b = 6.50(2) Å, c = 6.03(6) Å; V = 299.5(1) Å3]. The compound transforms into amorphous polymeric C2N2O at T > –68 °C. The results obtained were compared with recent findings and further discussed in the general context of C–N–(O) chemistry.
Reversal of glycogen storage disease type IIIa‐related cardiomyopathy with modification of diet
Authors: Dagli A. I. , Zori R. T. , McCune H. , Ivsic T. , Maisenbacher M. K. , Weinstein D. A.
Published: March 2009

Glycogen storage disease type III (GSD III) is caused by a deficiency in debranching enzyme, which leads to an accumulation of abnormal glycogen called limit dextrin in affected tissues. Muscle and liver involvement is present in GSD type IIIa, while the defect is limited to the liver only in GSD type IIIb. Besides skeletal muscle involvement, a cardiomyopathy resembling idiopathic hypertrophic cardiomyopathy is seen. Management consists of maintaining normoglycaemia by supplementation with cornstarch therapy and/or protein. While studies are lacking regarding the best treatment for skeletal muscle disease, a high‐protein diet was previously reported to be beneficial. No cases of improvement in cardiomyopathy have been reported. Our patient presented in infancy with hypoglycaemia and hepatomegaly. His prescribed management consisted of cornstarch supplementation and a high‐protein diet providing 20% of his total energy needs. At 16 years of age, he developed a severe cardiomyopathy with a left ventricular mass index of 209 g/m2. The cardiomyopathy remained stable on a protein intake of 20–25% of total energy. At age 22 years, the diet was changed to increase his protein intake to 30% of total energy and minimize his cornstarch therapy to only what was required to maintain normoglycaemia. Dramatic improvement in the cardiomyopathy occurred. Over one year, his left ventricular mass index decreased from 159.7 g/m2 to 78 g/m2 (normal 50–86 g/m2) and the creatine kinase levels decreased from 455 U/L to 282 U/L. Avoidance of overtreatment with carbohydrate and a high‐protein diet can reverse and may prevent cardiomyopathy.
Effect of ZnCdTe-Alloyed Nanocrystals on Polymer–Fullerene Bulk Heterojunction Solar Cells
Authors: Wang Yan , Hou Yanbing , Tang Aiwei , Feng Zhihui , Feng Bin , Li Yan , Teng Feng
Published: March 2009

The photovoltaic properties of solar cell based on the blends of poly[2-methoxy-5-(2-ethylhexoxy-1,4-phenylenevinylene) (MEH-PPV), fullerene (C60), and ZnCdTe-alloyed nanocrystals were investigated. Comparing the spectral response of photocurrent of the MEH-PPV:C60(+ZnCdTe) nanocomposite device with that of the devices based on MEH-PPV:C60and pristine MEH-PPV, one can find that the nanocomposite device exhibits an enhanced photocurrent. In comparing the composite devices with different ZnCdTe:[MEH-PPV + C60] weight ratios of 10 wt% (D1–1), 20 wt% (D1–2), 40 wt% (D1–3), and 70 wt% (D1–4), it was found that the device D1–3exhibits the best performance. The power conversion efficiency (η) is improved doubly compared with that of the MEH-PPV:C60device.
Radiocarbon deficiencies of US Gulf Coast lakes compromise paleo-hurricane records
Authors: Aharon Paul , Lambert W. Joe
Published: March 2009

Radiocarbon assays of sediments from Lake Shelby, US Gulf Coast, exhibit substantial 14C deficiencies of 9.3% and 4.7% for the limnic sapropel and associated fresh-water clams Rangia cuneata, respectively. Measured radiocarbon dates from the sapropel and clams require corrections of 785 ± 80 and 365 ± 90 14C yr (1σ), respectively, in order to achieve consistency with the radiocarbon time scale. Lake sediments of the US Gulf Coast serve as unique repositories of pre-historic hurricane strikes. Previously unrecognized radiocarbon deficiencies likely render compromised chronologies of the paleo-hurricane records, and erroneous estimates of return period and landfall probability that are derived from the storm chronologies. The recalculated severe hurricane chronologies suggest that the annual landfall probabilities of the last millennium on the US Gulf Coast are equal to, or higher than, the preceding three millennia.