bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation of encapsulated disperse dye dispersion for polyester inkjet printing ink
Authors: Fu Shaohai , Zhang Guifang , Du Changsen , Tian Anli
Published: March 2011

Encapsulated C.I. disperse dye blue 60 (disperse dye) was prepared with poly(styrene‐maleic acid) via phase separation method, followed by the preparation of dispersion and inkjet printing ink. The results showed that the encapsulated disperse dye dispersion had a small particle size, narrow particle size distribution, and excellent stability to centrifugal force, freeze‐thaw treatment, polyols and alkali and its rheological behavior belong to Newtonian fluid. The ink that prepared using this dispersion satisfied with the requirement of Mimaki JV4‐180 and showed an excellent printing performance at room temperature. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
The production of lipopeptides by Bacillus subtilis with desizing wastewater and application in soaping process
Authors: Li Ming‐Jian , Yang Qun , Shao Fen‐Juan , Lu Da‐Nian
Published: March 2011

In this article, a low‐cost medium for the production of lipopeptides by the Bacillus subtilis HSO121 was formulated with desizing wastewater as carbon source, which contains starch and its degradation products, and the lipopeptides were biosynthesized. As the result, the yield of crude lipopeptides was 1.03 g/L, and the critical micelle concentration was ∼ 50 mg/L. The chemical oxygen demand of the desizing wastewater after cultivation reduced to half compared with before cultivation. Separation of crude lipopeptides and its application as soaping agents in soaping process were investigated. The optimal soaping process was obtained at pH = 9 and 75°C with 0.05 g/L lipopeptides. Compared with traditional soaping process, lipopeptides soaping showed higher efficiency and higher colorfastness, and it is more energy efficient and more environmentally friendly process. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
A new composition–processing–property relationship for studying the tensile modulus‐phase plastic blends
Authors: Jodeh Shehdeh
Published: March 2011

Based on thermodynamic principles, a composition–processing–property relationship for predicting the modulus properties of multiphase plastic blends has been developed. This relationship describes the relative modulus of the blend in terms of the volume fraction and the index for the degree of mixing of an inclusion‐polymer in the matrix‐polymer. The relative modulus is defined as the ratio between the modulus of the blend and that of the matrix polymer. These blends include a nylon 6,6/polymethyl methacrylate(PMMA) system mixed using an injection molding process arid a nylon 6/ethylene‐vinyl acetate copolymer system mixed using a corotational extrusion process. Based on the values determined for the mixing index of the nylon 6,6/PMMA blends, a relationship between the mixing index and the fill time used in the injection molding has been developed. The results also imply that the degree of mixing of the blend mixed using a correlation extrusion process is better than that of the blend processed using an injection molding process. Using the above results, we now can scientifically develop new plastic blends and design optimum processing conditions for various automotive applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
In vitro controlled release of polymeric drug‐saccharide conjugates with ketoprofen, ibuprofen, and naproxen pendants
Authors: Wu Chengyao , Xie Jiangang , Branford‐White Christopher , Quan Jing , Zhu Limin
Published: March 2011

Polymerizable monomers of glucose and three types of nonsteroidal anti‐inflammatory drugs were prepared. Free radical polymerization of the resulting monomers was carried out in DMF. The polymers with drug pendent were characterized using FTIR, NMR, and GPC spectroscopy. Following hydrolysis of polymeric drug‐saccharide conjugates at 37°C, the cumulative released of naproxen, ibuprofen, and ketoprofen were 70, 55, and 30% after 10 days, respectively. Half‐lives (t1/2) of the copolymers were calculated through the first 12 h and these were found to be 4.2, 5.3, and 7.8 h, suggesting a slow and sustained drug release mechanism. The drug release profiles were also carried out at different pH, temperature, and ionic strength and solution varieties. It was concluded that different release profiles occurred and were dependent on temperature and pH. It was apparent that the polymeric drug‐saccharide conjugate had the potential to be developed as a system that enhances drug delivery. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
The effect of synthesis methods on the mechanical properties of self‐crosslinkable poly(n‐butyl methacrylate‐co‐N‐methylolacrylamide) films
Authors: Aguilar J. , Mendizábal E. , Nuño‐Donlucas S. M. , Arellano M. , Puig J. E. , Rabelero M.
Published: March 2011

The effects of particle size and parent polymer characteristics on the mechanical properties, gel fraction, and swelling index of self‐crosslinkable poly(n‐butyl methacrylate‐co‐N‐methylolacrylamide) films made by two‐stage emulsion or microemulsion polymerization in the presence of variable amounts of the chain transfer agent, n‐butyl mercaptan, are reported here. In films prepared with latexes made by microemulsion polymerization, the crosslinking degree increased greatly on curing; by contrast, in those made by emulsion polymerization, the crosslinking degree practically did not increase after curing. Stress–strain tests of uncured and cured films indicate that microemulsion‐made films are tougher than the emulsion‐made films. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Preparation of acrylic acid and AMPS cointercalated layered double hydroxide and its application for superabsorbent
Authors: Shi Shuxian , Guo Fang , Xia Yuzheng , Su Zhiqiang , Chen Xiaonong , Wei Min
Published: March 2011

This article reports the cointercalation of acrylic acid (AA) and 2‐acrylamido‐2‐methylpropane sulfonic acid (AMPS) in the interlayer region of Mg2Al layered double hydroxide (LDH) and the application of this inorganic–organic composite material in the field of water superabsorbent. The monomers of AA and AMPS were cointercalated into galleries of Mg2Al−LDH (denoted as AA−AMPS/LDH) with various molar ratios by ion‐exchange method, which was confirmed by powder X‐ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), and elemental analysis. The polymer‐based superabsorbent was prepared through in situ free‐radical aqueous copolymerization of AA and AMPS, with AA−AMPS/LDH as additive, N,N′‐methylenebisacrylamide (NMBA) as crosslinker and potassium persulfate (KPS) as initiator. The composition of this poly(AA‐co‐AMPS)/LDH was demonstrated as a good water superabsorbent. The LDH content, water absorbency, thermal stability, and swelling rate of this superabsorbent were also investigated in detail. Results showed that the incorporation of a 5 wt % AA−AMPS/LDH into polymer matrix increased its water absorbency significantly by 27.7% (in water) and by 51.5% (in 0.9 wt % NaCl solution). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Preparation of gold–poly(vinyl pyrrolidone) core–shell nanocomposites and their humidity‐sensing properties
Authors: Chen Xue Jiao , Zhang Jian , Ma Dian Fei , Hui Shi Chao , Liu Yan Li , Yao Wei
Published: March 2011

The humidity‐sensing properties of gold (Au)–poly(vinyl pyrrolidone) (PVP) core–shell nanocomposites were investigated. Au–PVP nanocomposites were synthesized and then incorporated into a capacitive‐type humidity sensor as a dielectric. Because of the adsorption/desorption of water molecules, the variation of capacitance under different humidity levels was examined by the capacitance–frequency conversion circuit and recorded by a LabVIEW system in terms of the frequency shift. As the relative humidity (RH) increased from 11.3 to 93%, the output frequency decreased monotonically, with a sen sitivity of about −136 Hz/% RH. Also, the good reproducibility and stability, fast response, and low hysteresis made the pellet a suitable candidate for humidity sensing. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Preparation and properties of crosslinked multiblock sulfonated poly(arylene ether sulfone) membranes for fuel cell applications
Authors: Zhang Xuan , Hu Zhaoxia , Zhang Sha , Chen Shouwen , Chen Shanshan , Liu Jianmei , Wang Lianjun
Published: March 2011

Novel multiblock poly(arylene ether sulfone)s were prepared by a two‐pot method from a phenoxide‐end‐capped fully disulfonated poly(arylene ether sulfone) oligomer and a fluoride‐end‐capped nonsulfonated poly(arylene ether sulfone) oligomer with block length of 10 as the hydrophilic and hydrophobic moieties, respectively, and were subsequently used as starting materials to be treated with phosphorous pentoxide (P2O5) to get crosslinked membranes. The crosslinking reaction occurred between the sulfonic acid groups and activated ortho‐hydrogen atoms to the ether linkage of the hydrophobic units in the presence of P2O5 during solution casting. The crosslinking ratio was simply controlled by the amount of P2O5, and the fundamental properties of the resulting crosslinked multiblock membranes were investigated in detail. The water uptake and solution uptake in methanol solutions decreased with increasing crosslinking ratio, but a comparable high proton conductivity was maintained in the uncrosslinked membranes. They exhibited isotropic swelling behavior and largely enhanced dimensional stability in water and methanol solutions, whereas the uncrosslinked one showed anisotropic swelling behavior. The oxidative stability of the crosslinked membranes was significantly enhanced by the formation of sulfonyl linkages. The high proton conductivities at 120°C and 50% relative humidity suggested promising applications in elevated temperatures. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Mechanism of degradation of poly(p‐phenylene benzobisoxazole) under hydrolytic conditions
Authors: Fu Qian , Zhang Huiru , Song Bo , Liu Xiaoyun , Zhuang Qixin , Han Zhewen
Published: March 2011

Poly(p‐phenylene benzobisoxazole) (PBO) fiber has received great interest because of its excellent mechanical properties and good thermal stability. The objective of this study was to expose degradation mechanism of PBO under neutral and acidic conditions by molecular mass and Fourier transform infrared (FTIR) spectroscopy. Results were not consistent with the classic degradation mechanism, which indicates that degradation should occur through the ring opening and chain scission of the benzoxazole ring. The FTIR absorption spectra of PBO suggested that the o‐hydroxy amide linkage (the open ring structure) was present in the PBO molecule chain to some extent because of the incomplete polymerization. Further investigation showed that hydrolysis might occur in the open ring section during hydrolytic degradation. Based on the experimental data, a new degradation mechanism was proposed. It suggests that, in the early and middle stages, hydrolysis occurred primarily in the o‐hydroxy amide linkage of the open ring. The concentration of the o‐hydroxy amide structure determined the speed of degradation of PBO. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Crack initiation and propagation in circular rubber bearings subjected to cyclic compression
Authors: Chou Hsoung‐Wei , Huang Jong‐Shin
Published: March 2011

The fatigue failure mechanism of rubber bearings under cyclic compression is important in evaluating their fatigue lives and thus is analyzed theoretically and numerically here. At first, the stress distributions in a bonded rubber cylinder derived from three different existing models were utilized to calculate the cracking energy densities within it. Next, the location of fatigue crack initiation and the direction of subsequent crack propagation in circular rubber bearings were consecutively determined. Furthermore, finite element numerical results were compared to those obtained theoretically from the three models to check their validity in predicting the fatigue crack initiation and propagation in circular rubber bearings. Based on the quasi‐statically theoretical and numerical results, it is found that the fatigue cracks initiate first at the outermost boundary between rubber and steel plates and propagate later inwards to the center of circular rubber bearings. The corresponding fatigue failure mechanism obtained theoretically and numerically is consistent with experimental findings reported previously. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Using embryology screencasts: A useful addition to the student learning experience?
Authors: Evans Darrell J.R.
Published: March 2011

Although podcasting has been a well used resource format in the last few years as a way of improving the student learning experience, the inclusion of enhanced audiovisual formats such as screencasts has been less used, despite the advantage that they work well for both visual and auditory learners. This study examines the use of and student reaction to a set of screencasts introduced to accompany embryology lectures within a second year module at Brighton and Sussex Medical School. Five mini‐lecture screencasts and one review quiz screencast were produced as digital recordings of computer screen output with audio narration and released to students via the managed learning environment (MLE). Analysis of server log information from the MLE showed that the screencasts were accessed by many of the students in the cohort, although the exact numbers were variable depending on the screencast. Students accessed screencasts at different times of the day and over the whole of the access period, although maximum downloads were predictably recorded leading up to the written examination. Quantitative and qualitative feedback demonstrated that most students viewed the screencasts favorably in terms of usefulness to their learning, and end‐of‐module written examination scores suggest that the screencasts may have had a positive effect on student outcome when compared with previous student attainment. Overall, the development of a series of embryology screencasts to accompany embryology lecture sessions appears to be a useful addition to learning for most students and not simply an innovation that checks the box of “technology engagement.” Anat Sci Educ 4: 57–63, 2011. © 2011 American Association of Anatomists.
Linear and Hyperbranched Electron‐Acceptor Supramolecular Oligomers
Authors: Santos José , Pérez Emilio M. , M. Illescas Beatriz , Martín Nazario
Published: March 2011

The nanometric organization of p‐type and n‐type materials is expected to facilitate charge mobility in OSCs, thereby preventing recombination and enhancing efficiency. Herein, the synthesis and self‐assembly of monomers comprising one or two units of a TCAQ tweezer covalently connected to a fullerene derivative is reported. Such molecules self‐assemble in solution (NMR) and on surfaces (AFM) to form linear and hyperbranched supramolecular oligomers, respectively. The self‐assembly process was also found to have very little influence on the electronic properties of the electroactive units of the monomers (CV and UV/Vis), as was expected from their matching character. These polymers constitute two of the first examples of n‐type supramolecular polymers reported to date.
Paper 6: EUROCAT member registries: Organization and activities
Authors: Greenlees Ruth , Neville Amanda , Addor Marie–Claude , Amar Emmanuelle , Arriola Larraitz , Bakker Marian , Barisic Ingeborg , Boyd Patricia A. , Calzolari Elisa , Doray Berenice , Draper Elizabeth , Emil Vollset Stein , Garne Ester , Gatt Miriam , Haeusler Martin , Kallen Karin , Khoshnood Babak , Latos–Bielenska Anna , Martinez–Frias Maria–Luisa , Materna–Kiryluk Anna , Matias Dias Carlos , McDonnell Bob , Mullaney Carmel , Nelen Vera , O'Mahony Mary , Pierini Anna , Queisser–Luft Annette , Randrianaivo–Ranjatoélina Hanitra , Rankin Judith , Rissmann Anke , Ritvanen Annukka , Salvador Joaquin , Sipek Antonin , Tucker David , Verellen–Dumoulin Christine , Wellesley Diana , Wertelecki Wladimir
Published: March 2011

BACKGROUND

EUROCAT is a network of population‐based congenital anomaly registries providing standardized epidemiologic information on congenital anomalies in Europe. There are three types of EUROCAT membership: full, associate, or affiliate. Full member registries send individual records of all congenital anomalies covered by their region. Associate members transmit aggregate case counts for each EUROCAT anomaly subgroup by year and by type of birth. This article describes the organization and activities of each of the current 29 full member and 6 associate member registries of EUROCAT.

METHODS

Each registry description provides information on the history and funding of the registry, population coverage including any changes in coverage over time, sources for ascertaining cases of congenital anomalies, and upper age limit for registering cases of congenital anomalies. It also details the legal requirements relating to termination of pregnancy for fetal anomalies, the definition of stillbirths and fetal deaths, and the prenatal screening policy within the registry. Information on availability of exposure information and denominators is provided. The registry description describes how each registry conforms to the laws and guidelines regarding ethics, consent, and confidentiality issues within their own jurisdiction. Finally, information on electronic and web‐based data capture, recent registry activities, and publications relating to congenital anomalies, along with the contact details of the registry leader, are provided.

CONCLUSIONS

The registry description gives a detailed account of the organizational and operational aspects of each registry and is an invaluable resource that aids interpretation and evaluation of registry prevalence data. Birth Defects Research (Part A) , 2011.© 2011 Wiley‐Liss, Inc.
The Relation Between Obtained Preference Value and Reinforcer Potency
Authors: Graff Richard B. , Larsen Jillian
Published: March 2011

Stimulus preference assessments often include items suspected to be highly preferred. If only high‐preference stimuli are assessed, preference hierarchies may not accurately predict the results of reinforcer assessments (RA). In this study, paired‐stimulus (PS) preference assessments using items suspected to be preferred (PS‐1) generated distinct preference hierarchies. Subsequent RAs (RA‐1) indicated that high‐preference and low‐preference stimuli were associated with similar response rates. Additional assessments (PS‐2) were then conducted, using the least‐preferred item from PS‐1 plus seven new stimuli. The least‐preferred items on PS‐1 ranked as most preferred on PS‐2, and on RA‐2, the top‐ranked items functioned as reinforcers, but low‐ranked items did not. Implications for incorporating low‐preference items into clinical/educational programming are discussed. Copyright © 2011 John Wiley & Sons, Ltd.
A Site‐Saturated Mutagenesis Study of Pentaerythritol Tetranitrate Reductase Reveals that Residues 181 and 184 Influence Ligand Binding, Stereochemistry and Reactivity
Authors: Toogood Helen S. , Fryszkowska Anna , Hulley Martyn , Sakuma Michiyo , Mansell David , Stephens Gill M. , Gardiner John M. , Scrutton Nigel S.
Published: March 2011

We have conducted a site‐specific saturation mutagenesis study of H181 and H184 of flavoprotein pentaerythritol tetranitrate reductase (PETN reductase) to probe the role of these residues in substrate binding and catalysis with a variety of α,β‐unsaturated alkenes. Single mutations at these residues were sufficient to dramatically increase the enantiopurity of products formed by reduction of 2‐phenyl‐1‐nitropropene. In addition, many mutants exhibited a switch in reactivity to predominantly catalyse nitro reduction, as opposed to CC reduction. These mutants showed an enhancement in a minor side reaction and formed 2‐phenylpropanal oxime from 2‐phenyl‐1‐nitropropene. The multiple binding conformations of hydroxy substituted nitro‐olefins in PETN reductase were examined by using both structural and catalytic techniques. These compounds were found to bind in both active and inhibitory complexes; this highlights the plasticity of the active site and the ability of the H181/H184 couple to coordinate with multiple functional groups. These properties demonstrate the potential to use PETN reductase as a scaffold in the development of industrially useful biocatalysts.
Progress in Carbonylative‐Heck Reactions of Aryl Bromides: Catalysis and DFT Studies
Authors: Wu Xiao‐Feng , Jiao Haijun , Neumann Helfried , Beller Matthias
Published: March 2011

Improved palladium‐catalyzed carbonylative Heck coupling reactions of aryl bromides with styrenes are described. Applying a [{(cinnamyl)PdCl}2]/PPh3 catalyst system, >20 chalcones with various functional groups were synthesized in 45–90 % yield. The reaction mechanism of this coupling reaction was studied by detailed DFT computations, which show that the carbonylation step is reversible.
Micronization of Fluticasone Propionate using Supercritical Antisolvent (SAS) Process
Authors: Su C.‐S. , Lo W.‐S. , Lien L.‐H.
Published: March 2011

The micronization of an asthma active pharmaceutical ingredient, fluticasone propionate, using the supercritical antisolvent (SAS) process was investigated in this study. The most commonly used supercritical carbon dioxide was employed as the antisolvent. The effects of five process parameters, including operating temperature, operating pressure, solution flow rate, solution concentration, and nozzle diameter, were compared and discussed. The physical properties of micronized fluticasone propionate were examined by the particle size analyzer, the scanning electron microscope and X‐ray diffractometer. The cross interaction effect of operating temperature and pressure was observed in the SAS treatment of fluticasone propionate and verified by the method of calculated mixture critical point (MCP), using the predictive Soave‐Redlich‐Kwong equation of state. Operation slightly above the MCP was suggested for successful micronization of fluticasone propionate.
Electrospray Crystallization for High‐Quality Submicron‐Sized Crystals
Authors: Radacsi N. , Stankiewicz A. I. , Creyghton Y. L. M. , van der Heijden A. E. D. M. , ter Horst J. H.
Published: March 2011

Nano‐ and submicron‐sized crystals are too small to contain inclusions and are, therefore, expected to have a higher internal quality compared to conventionally sized particles (several tens to hundreds of microns). Using electrospray crystallization, nano‐ and submicron‐sized crystals can be easily produced. With the aid of electrospray crystallization, a mist of ultrafine solution droplets is generated and subsequent solvent evaporation leads to crystallization of submicron‐sized crystals. Using cyclotrimethylene trinitramine (RDX) solutions in acetone, the conditions for a stable and continuous jet were established. At relatively small nozzle diameters and relatively low potential differences, hollow spheres of RDX crystals were observed. At a higher nozzle diameter and potential difference and in the region of a continuous jet, RDX crystals with an average size of around 400 nm could be produced. In order to test the quality of the submicron‐sized energetic material, impact and friction sensitivity tests were carried out. The test results indicate that the submicron‐sized product had reduced friction sensitivity, indicating a higher internal quality of the crystalline product.
Solvent and Substituent Effects on the Photochemistry of Norbornadiene‐Diarylacetylene Pauson–Khand Adducts
Authors: Ji Yining , Verdaguer Xavier , Riera Antoni
Published: March 2011

The photochemistry of Pauson–Khand cycloadducts of norbornadiene with a series of bis‐aryl alkynes has been studied. Two types of photochemical transformation take place: photorearrangement to tricyclic ketones or photochemical 6π electrocyclization. High selectivity levels have been attained for each pathway, controlled by the polarity of the solvent, irradiation wavelength, and presence (or absence) of oxygen.
Towards New Molecular Photocatalysts for CO2 Reduction: Photo‐Induced Electron Transfer versus CO Dissociation within [Os(NN)(CO)2Cl2] Complexes
Authors: Chauvin Jérôme , Lafolet Frédéric , Chardon‐Noblat Sylvie , Deronzier Alain , Jakonen Minna , Haukka Matti
Published: March 2011

Optical excitation in the visible region of trans‐(Cl)‐[Os(bpy)(CO)2Cl2] (bpy=2,2′‐bipyridine; C1) and trans‐(Cl)‐[Os(dmbpy)(CO)2Cl2] (dmbpy=4,4′‐dimethyl 2,2′‐bipyridine; C2) is known to induce the common CO dissociation reaction. However, the quantum yield of the reactions is less than 0.15, although C1 and C2 display pronounced photoluminescence in the visible region at room temperature with a lifetime of few tens of nanoseconds. Taking into account the characteristics of their emitting state, we have investigated the capability of C1 and C2 to act as a photosensitiser in redox reactions in different solvents (MeCN, PrCN and DMF). The efficient oxidation and reduction of both complexes under continuous irradiation in the presence of a sacrificial electron acceptor or donor is reported here. The photo‐induced transformations and the nature of the resulting compounds were analysed by UV/Vis and IR spectroscopies and cyclic voltammetry. Photo‐induced oxidation of C1 and C2 leads to the corresponding monocarbonyl oxidised species, whereas photo‐induced reduction under argon leads mainly to the formation of the corresponding Os‐bonded molecular wires P1 and P2 after exchange of two electrons associated with the loss of two chloro ligands. The chemical yield of the latter reaction (around 65 %) becomes quantitative by adding [Ru(bpy)3]2+ as an external redox photosensitiser. This behaviour has been used to photocatalyse the two electron, two proton conversion of CO2 to CO. Turnover numbers (TON) of 11.5 and 19.5 have been obtained respectively for C1 and C2 after 4.5 h of irradiation under CO2 in DMF with triethanolamine as the electron donor. TON can be slightly increased by adding [Ru(bpy)3]2+ to the solution.
Ti/Pd Bimetallic Systems for the Efficient Allylation of Carbonyl Compounds and Homocoupling Reactions
Authors: Millán Alba , Campaña Araceli G. , Bazdi Btissam , Miguel Delia , Álvarez de Cienfuegos Luis , Echavarren Antonio M. , Cuerva Juan M.
Published: March 2011

The allylation, crotylation and prenylation of aldehydes and ketones with stable and easily handled allylic carbonates is promoted by a Ti/Pd catalytic system. This Ti/Pd bimetallic system is especially convenient for the allylation of ketones, which are infrequent substrates in other related protocols, and can be carried out intramolecularly to yield five‐ and six‐membered cyclic products with good stereoselectivities. In addition, Ti/Pd‐mediated reductions and Würtz‐type dimerisation reactions can be readily carried out from allyl carbonates and carboxylates.
Thermal Activation of NH Bonds by Transition‐metal Oxide Cations: Does a Hierarchy Exist in the First Row?
Authors: Kretschmer Robert , Zhang Xinhao , Schlangen Maria , Schwarz Helmut
Published: March 2011

The thermal reactions of first‐row transition‐metal oxide cations [MO]+ (M=Sc–Ni, Zn) with ammonia have been studied by gas‐phase experiments and computational methods. The activation of NH bonds is brought about by the monoxides of the middle and late 3d metals Mn–Ni and Zn. The two primary reaction channels correspond to dehydration, which leads to [M(NH)]+, and hydrogen‐atom abstraction to form [M(OH)]+. Oxygen‐atom transfer from [MO]+ to NH3 to produce neutral or ionized hydroxylamine was observed as a minor channel for some of the late transition‐metal oxides. The computational analysis of these reactions, which was aimed at elucidating the reaction mechanisms and to uncover possible periodic trends across the first row, have been performed for the couples [MO]+/NH3 (M=Sc–Zn). Dehydration is found to be endothermic for the oxides of scandium to vanadium and exothermic for the other systems. Hydrogen‐atom abstraction becomes exothermic starting with [MnO]+ and, finally, oxygen‐atom transfer is feasible for the cationic oxides of nickel to zinc.
Novel Cinnamyl Hydroxyamides and 2‐Aminoanilides as Histone Deacetylase Inhibitors: Apoptotic Induction and Cytodifferentiation Activity
Authors: Valente Sergio , Tardugno Maria , Conte Mariarosaria , Cirilli Roberto , Perrone Andrea , Ragno Rino , Simeoni Silvia , Tramontano Anna , Massa Silvio , Nebbioso Angela , Miceli Marco , Franci Gianluigi , Brosch Gerald , Altucci Lucia , Mai Antonello
Published: March 2011

Four novel series of cinnamyl‐containing histone deacetylase (HDAC) inhibitors 1–4 are described, containing hydroxamate (1 and 3) or 2‐aminoanilide (2 and 4) derivatives. When screened against class I (maize HD1‐B and human HDAC1) and class II (maize HD1‐A and human HDAC4) HDACs, most hydroxamates and 2‐aminoanilides displayed potent and selective inhibition toward class I enzymes. Immunoblotting analyses performed in U937 leukemia cells generally revealed high acetyl‐H3 and low acetyl‐α‐tubulin levels. Exceptions are compounds 3 f–i, 3 m–o, and 4 k, which showed higher tubulin acetylation than SAHA. In U937 cells, cell‐cycle blockade in either the G2/M or G1/S phase was observed with 1–4. Five hydroxamates (compounds 1 h–l) effected a two‐ to greater than threefold greater percent apoptosis than SAHA, and in the CD11c cytodifferentiation test some 2‐aminoanilides belonging to both series 2 and 4 were more active than MS‐275. The highest‐scoring derivatives in terms of apoptosis (1 k, 1 l) or cytodifferentiation (2 c, 4 n) also showed antiproliferative activity in U937 cells, thus representing valuable tools for study in other cancer contexts.
Genetic variation in the transforming growth factor‐β signaling pathway and survival after diagnosis with colon and rectal cancer
Authors: Slattery Martha L. , Lundgreen Abbie , Herrick Jennifer S. , Wolff Roger K. , Caan Bette J.
Published: March 2011

BACKGROUND:

The transforming growth factor‐β (TGF‐β) signaling pathway is involved in many aspects of tumorigenesis, including angiogenesis and metastasis. The authors evaluated this pathway in association with survival after a diagnosis of colon or rectal cancer.

METHODS:

The study included 1553 patients with colon cancer and 754 patients with rectal cancer who had incident first primary disease and were followed for a minimum of 7 years after diagnosis. Genetic variations were evaluated in the genes TGF‐β1 (2 single nucleotide polymorphisms [SNPs]), TGF‐β receptor 1 (TGF‐βR1) (3 SNPs), smooth muscle actin/mothers against decapentaplegic homolog 1 (Smad1) (5 SNPs), Smad2 (4 SNPs), Smad3 (37 SNPs), Smad4 (2 SNPs), Smad7 (11 SNPs), bone morphogenetic protein 1 (BMP1) (11 SNPs), BMP2 (5 SNPs), BMP4 (3 SNPs), bone morphogenetic protein receptor 1A (BMPR1A) (9 SNPs), BMPR1B (21 SNPs), BMPR2 (11 SNPs), growth differentiation factor 10 (GDF10) (7 SNPs), Runt‐related transcription factor 1 (RUNX1) (40 SNPs), RUNX2 (19 SNPs), RUNX3 (9 SNPs), eukaryotic translation initiation factor 4E (eiF4E) (3 SNPs), eukaryotic translation initiation factor 4E‐binding protein 3 (eiF4EBP2) (2 SNPs), eiF4EBP3 (2 SNPs), and mitogen‐activated protein kinase 1 (MAPK1) (6 SNPs).

RESULTS:

After adjusting for American Joint Committee on Cancer stage and tumor molecular phenotype, 12 genes and 18 SNPs were associated with survival in patients with colon cancer, and 7 genes and 15 tagSNPs were associated with survival after a diagnosis of rectal cancer. A summary score based on “at‐risk” genotypes revealed a hazard rate ratio of 5.10 (95% confidence interval, 2.56‐10.15) for the group with the greatest number of “at‐risk” genotypes; for rectal cancer, the hazard rate ratio was 6.03 (95% confidence interval, 2.83‐12.75).

CONCLUSIONS:

The current findings suggest that the presence of several higher risk alleles in the TGF‐β signaling pathway increase the likelihood of dying after a diagnosis of colon or rectal cancer. Cancer 2011;. © 2011 American Cancer Society.
Study of the Efficiency of UV and Visible‐Light Photocatalytic Oxidation of Methanol on Mesoporous RuO2–TiO2 Nanocomposites
Authors: Ismail Adel A. , Robben Lars , Bahnemann Detlef W.
Published: March 2011

Mesoporous RuO2–TiO2 nanocomposites at different RuO2 concentrations (0–10 wt %) are prepared through a simple one‐step sol–gel reaction of tetrabutyl orthotitanate with ruthenium(III) acetylacetonate in the presence of an F127 triblock copolymer as structure‐directing agent. The thus‐formed RuO2–TiO2 network gels are calcined at 450 °C for 4 h leading to mesoporous RuO2–TiO2 nanocomposites. The photocatalytic CH3OH oxidation to HCHO is chosen as the test reaction to examine the photocatalytic activity of the mesoporous RuO2–TiO2 nanocomposites under UV and visible light. The photooxidation of CH3OH is substantially affected by the loading amount and the degree of dispersion of RuO2 particles onto the TiO2, which indicates the exclusive effect of the RuO2 nanoparticles on this photocatalytic reaction under visible light. The measured photonic efficiency ξ=0.53 % of 0.5 wt % RuO2–TiO2 nanocomposite for CH3OH oxidation is maximal and the further increase of RuO2 loading up to 10 wt % gradually decreases this value. The cause of the visible‐light photocatalytic behavior is the incorporation of small amounts of Ru4+ into the anatase lattice. On the other hand, under UV light, undoped TiO2 shows a very good photonic efficiency, which is more than three times that for commercial photocatalyst, P‐25 (Evonik–Degussa); however, addition of RuO2 suppresses the photonic efficiency of TiO2. The proposed reaction mechanism based on the observed behavior of RuO2–TiO2 photocatalysts under UV and visible light is explored.
Crystallization field and rate study for the formation of single phase sodium‐potassium and potassium clinoptilolite
Authors: Güvenir Ö. , Kalıpçılar H. , Çulfaz A.
Published: March 2011

Reproducible synthesis of clinoptilolite as the single crystalline phase was achieved in the narrow crystallization field at or around the nominal batch composition of 2.1(Na2O+K2O):Al2O3:10SiO2:110H2O at 140 °C. Clinoptilolites of high purity were crystallized in the pure sodium or mixed sodium‐potassium cation systems. Partial replacement of hydroxyl anions with the salts of carbonates or chlorides also yielded clinoptilolite as the single crystalline phase although at lower crystallization rates. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Managing gas purity in epitaxial growth
Authors: Succi M. , Pirola S. , Ruffenach S. , Briot O.
Published: March 2011

The development of high brightness LEDs is being studied worldwide due to the expectation to replace present light sources because of the higher efficiency and estimated lifetime. The deposition of the epitaxial layers is the most critical step of the LED manufacturing process and has to be carried‐out in well controlled conditions to get the necessary uniformity of the epitaxial layers and the proper cleanliness. The most common technology to grow the epitaxial layers is MOVPE, a technology that requires a large quantity of gas to transport the precursors into the process reactor. Control of the cleanliness of the gases used during the process (hydrogen, ammonia, arsine, etc) is necessary to obtain highly efficient and reproducible devices. However, even the use of the cleanest gas source cannot avoid the introduction of impurities when the gas is used in the process reactor. In fact there are several causes that can degrade the actual purity level: the degree of emptiness of the source cylinder, improper procedures during the change out of the cylinder or outgassing from the components in the gas distribution system. These effects can be even worse in research centers where the gas consumption is low and not continuous. A common way to get rid of the above mentioned problems is the adoption of point of use purifiers. Results showing the improvements in the gas quality by adopting point of use purifiers will be presented and discussed. The differences between some widely used hydrogen purification technologies in the compound semiconductor applications will also be evaluated. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Formation of calcium phosphates by vapour diffusion in highly concentrated ionic micro‐droplets
Authors: Iafisco M. , Delgado‐López J. M. , Gómez‐Morales J. , Hernández‐Hernández M. A. , Rodríguez‐Ruiz I. , Roveri N.
Published: March 2011

In this work we have used the sitting drop vapour diffusion technique, employing the “crystallization mushroom ” to analyze the evolution of calcium phosphate crystallization in micro‐droplets containing high initial concentrations of Ca2+ and HPO42‐. The decomposition of NH4HCO3 solution produces vapours of NH3 and CO2 which diffuse through the droplets containing an aqueous solution of Ca(CH3COO)2 and (NH4)2HPO4. The result is the increase of pH by means of the diffusion of NH3 gas and the doping of the calcium phosphate with CO32‐ ions by means of the diffusion of CO2 gas. The pH of the crystallization process is monitored and the precipitates at different times are characterized by XRD, FTIR, TGA, SEM and TEM techniques. The slow increase of pH and the high concentration of Ca2+ and HPO42‐ in the droplets induce the crystallization of three calcium phosphate phases: dicalcium phosphate dihydrate (DCPD, brushite), octacalcium phosphate (OCP) and carbonate‐hydroxyapatite (HA). The amount of HA nanocrystals with needle‐like morphology and dimensions of about 100 nm, closely resembling the inorganic phase of bones, gradually increases, with the precipitation time up to 7 days, whereas the amount of DCPD, growing along the b axis, increases up to 3 days. Then, DCDP crystals start to hydrolyze yielding OCP nanoribbons and HA nanocrystals. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of substrate and film thickness on structural, optical and electrical properties of ZnO thin films
Authors: Gopalakrishnan N. , Balakrishnan L. , Latha K. , Gowrishankar S.
Published: March 2011

Transparent Zinc Oxide (ZnO) thin films have been grown on Si (100) and Sapphire (0001) substrates by RF magnetron sputtering for different growth time intervals (10, 30 and 60 min) to study the substrate and thickness effects. All the films have been grown at a substrate temperature of 450 °C. It has been found that the average growth rate on Si (100) substrate (8.6 nm/min) is higher than that on Sapphire (0001) substrate (2.6 nm/min) in an identical growth condition which clearly shows the virtual role of substrates. The lower growth rate on Sapphire (0001) suggests that the increasingly ordered and uniform growth due to less lattice mismatch. The grown films have been characterized by X‐ray diffraction (XRD), Reflectance, Photoluminescence (PL) and Hall measurements. The XRD result (FWHM) reveals that for lower growth time, the films grown on Si (100) is better than on Sapphire (0001). Conversely, for higher growth time, the films grown on Sapphire (0001) is better than on Si (100). The variation of strain behavior due to thickness on both substrates has been justified by UV‐Vis reflectance, photoluminescence and Hall effect measurements. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
MOCVD of Vertically Aligned ZnO Nanowires Using Bidentate Ether Adducts of Dimethylzinc
Authors: Ashraf Sobia , Jones Anthony C. , Bacsa John , Steiner Alexander , Chalker Paul R. , Beahan Peter , Hindley Sarah , Odedra Rajesh , Williams Paul A. , Heys Peter N.
Published: March 2011

The dimethylzinc‐bidentate ether adducts [Me2Zn(1,4‐dioxane)] (1), [Me2Zn(1,2‐dimethoxyethane)] (2) and [Me2Zn(1,4‐thioxane)] (3) are used as precursors for the growth of vertically aligned zinc oxide (ZnO) nanowires (NWs) by liquid‐injection, metal‐organic (MO)CVD. The ZnO NWs are deposited on Si(111) and F‐doped SnO2/glass substrates in the absence of a seed catalyst. The precursors (1) and (2) are used to deposit ZnO NWs at substrate temperatures of 450 °C and 500 °C, whilst higher deposition temperatures of 550–600 °C are necessary to obtain ZnO NWs using (3). X‐ray diffraction (XRD) data show that the NWs grown from all three adduct precursors are deposited in the wurtzitic ZnO phase. Room‐temperature photoluminescence (PL) data for the ZnO NWs grown using (1) and (2) show an intense peak at 3.28 eV due to near band‐edge emission with a very low intensity of defect‐related green luminescence at 2.42 eV. In contrast, room‐temperature PL data for the ZnO NWs deposited using (3) is dominated by deep centre, defect‐related emission at 2.42 eV. Auger electron spectroscopy (AES) shows that the ZnO films deposited from (1) and (2) are high purity with no detectable carbon, but the ZnO films grown from (3) are contaminated with sulfur (1 at.‐%). Single‐crystal X‐ray structures show that (1) is polymeric containing bridging 1,4‐dioxane ligands while (2) is a monomeric complex featuring a chelating 1,2‐dimethoxyethane ligand. The wide [Me‐Zn‐Me] bond angles in (1) and (2) (152.0(3)° and 154.5(2)°, respectively) suggest moderately weak [Me2Zn]‐ligand interactions. Complex (3) is polymeric and exhibits nearly linear [Me‐Zn‐Me] bond angles, indicative of much weaker [Me2Zn]‐ligand interactions.
Forest, climate and water issues in Europe
Authors: Bredemeier Michael
Published: March 2011

The particular European perspective on current forest and water issues is outlined in three focal areas: water supply, water quality, and water‐related hazards. Much of the synopsis relies on contributions brought together within the European COST consortium ‘Forest management and the water cycle’, which is operating from 2007 to 2011. Under the currently projected climate change (CC) scenarios for Europe, the humidity gradient across the sub‐continent from moist Northwest to dry Southeast will probably intensify, bringing about potentially more flooding problems at the ‘wet end’, and more drought and related problems (wildfires, salination) at the ‘dry end’. Careful planning of management is essential wherever tradeoff situations between forest growth and water yield emerge. The water quality issue in Europe is not as pressing as it was a few decades ago. Much has been achieved on account of successful water‐ and air‐pollution control. Particularly, the acidification pressure on forest soils and their water‐related systems was much relieved, due to strongly declining acidic deposition over the past 30 years. Forests and their appropriate management for optimizing water retention can support flood control, but with clear limitations under very strong and catastrophic events. The contribution to flood control is more important under ‘normal’ conditions than under extremes. Important controls are infiltration capacity and the status of water saturation prior to the rain event, i.e. the still available storage capacity. The safeguarding of water quality is seen as the most important single aspect among forest‐water relations. Copyright © 2011 John Wiley & Sons, Ltd.
Synthesis and Characterization of Platinum(II) Complexes with a Diazenecarboxamide‐Appended Picolyl‐Triazole Ligand
Authors: Urankar Damijana , Pevec Andrej , Košmrlj Janez
Published: March 2011

The coordination of the diazenecarboxamides, which were functionalized with the 1‐(2‐picolyl)‐1H‐1,2,3‐triazole moiety 1, to platinum(II) were studied, where K2[PtCl4] and cis‐[PtCl2(DMSO)2] were used as the platinum sources. The picolyl‐triazole (pictri) binding unit enabled chelation to the metal centre through the 1,2,3‐triazole N2 and the pyridyl nitrogen atoms under mild reaction conditions. When cis‐[PtCl2(DMSO)2] was used, with CH2Cl2 or CH3CN as the reaction solvents, the pure, stable diamminedichloridoplatinum(II) complexes 2 were isolated by filtration in 39 to 83 % yield. The products were structurally characterized in solution by 1H, 13C and 195Pt NMR spectroscopy. The 195Pt NMR chemical shifts for 2 appear in the region of –2203 to –2207 ppm. The structure of complex 2a was confirmed by single‐crystal X‐ray crystallography. The formation of the platinum complexes 2 was monitored using NMR spectroscopy. The complexation with cis‐[PtCl2(DMSO)2] in [D7]dmf proceeded through several intermediates, as indicated by the 195Pt NMR spectra with resonances in the range of –3055 to –2907 ppm. Similarly, the reaction of cis‐[PtCl2(DMSO)2] with diazenecarboxamide, which was functionalized with the nonchelating 1‐(2‐aminoethyl)‐1,2,3‐triazole derivative, was examined by NMR spectroscopy.
Performance of Dye‐Sensitized Solar Cells Based on MWCNT/TiO2–xNx Nanocomposite Electrodes
Authors: Guo Wei , Shen Yihua , Wu Liqiong , Gao Yurong , Ma Tingli
Published: March 2011

Multiwall carbon nanotube (MWCNT) fibrils were introduced into TiO2–xNx photoelectrodes to enhance charge collection efficiency as charge‐transport pathways. For comparison, we also synthesized MWCNT/TiO2 nanocomposites to fabricate dye‐sensitized solar cells (DSCs). The effect of MWCNTs on the photovoltaic performance of the DSCs was studied in detail. The performance of DSCs based on MWCNT/TiO2–xNx differs significantly from that of MWCNT/TiO2 photoelectrodes. A high energy conversion efficiency of 7.66 % was achieved in the dye‐sensitized MWCNT/TiO2 nanocomposites solar cells. The results show that remarkable enhancement of ca. 33 % and ca. 40 % in the conversion efficiency (η) and short‐circuit photocurrent density (Jsc), respectively, occurrs for the DSCs based on MWCNT/TiO2 than those made of pure TiO2 electrodes. The energy conversion efficiency of DSCs based on TiO2–xNx electrodes was 6.98 %, which is similar to that of MWCNT/TiO2–xNx DSCs (6.88 %–5.17 %). We also investigated the charge collection efficiency, electron transport, electron lifetime, and photocurrent transient behavior by electrochemical analysis. The introduced MWCNTs exhibit a smaller sheet resistance and electron transfer resistance, as well as a longer electron lifetime. A 20 % enhancement in the charge collection efficiency is achieved in the nanocomposite DSCs.
The U28 Nanosphere: What's Inside?
Authors: Nyman May , Rodriguez Mark A. , Alam Todd M.
Published: March 2011

Polyoxometalate‐like behavior of actinyl‐peroxide anions in aqueous alkaline media has been recently unveiled in the form of more than 20 reported crystal structures of clusters, each with 20–60 uranyl polyhedra composing capsule‐like topologies. There is now opportunity to fully develop this new polyoxometalate (POM) family to include redox behavior, non‐aqueous chemistry, complex materials from cluster building blocks, cluster‐counterion interactions, etc. To pursue these opportunities, reliable syntheses rooted in an understanding of cluster assembly processes are imperative. To this end, using the U28 nanosphere [UO2(O2)1.5]28 as an example, we report high yield syntheses of a series of four U28 salts that feature different templating cations (K, Rb, Cs) and anions [uranyl monomer, Nb(O2)4 and Ta(O2)4]. The key to assembly and stability of U28 is both 1) synthetic conditions that are not extreme or dynamic, and 2) templating cations and anions that ideally match each other and the topology of the capsule interior. U28 salts are characterized in the solid‐state by powder and single‐crystal X‐ray diffraction and infrared spectroscopy. Furthermore, Cs‐templated U28 is re‐dissolved and characterized by 133Cs NMR; providing information on solution stability, and revealing the interaction of the internal templating Cs+ with the central templating anion. While Cs+ internal to the cluster remains inside when U28 is dissolved in a Na salt solution, the internal K+ will rapidly exchange with Na+, providing new routes to other cluster topologies and compositions.