bluuebunny/crossref_metadata_2025_split huggingface dataset:
An elastoplastic evaluation of the stress state around cylindrical openings based on a closed multiaxial yield surface
Authors: Li Li , Aubertin Michel 
Published: April 2008

AbstractThere are many applications encountered in geo‐engineering where there is a need to evaluate the stress state around circular openings. This paper presents a new analytical solution for evaluating the stresses around a cylindrical excavation in an elastoplastic medium defined by the closed MSDPu yield surface. The proposed formulation takes into account the 3D stress geometry with a plasticity criterion that intersects the mean stress axis on the positive (compressive) and negative (tensile) sides. The results shown here illustrate how the stress distribution and yielding zone size are affected by various influence factors. Validation of the proposed formulation is made by comparing calculated results with existing analytical solutions and a numerical simulation. Copyright © 2008 John Wiley & Sons, Ltd.
A new composite sorbent for water and dye uptake: Highly swollen acrylamide/2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid/clay hydrogels crosslinked by 1,4‐butanediol dimethacrylate
Authors: Kundakci Semiha , Üzüm Ömer Barış , Karadağ Erdener 
Published: April 2008

AbstractA novel type of highly swollen hydrogels based on acrylamide (AAm) with 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid (AMPS) and clay such as bentonite (Bent) crosslinked by 1,4‐butanediol dimethacrylate (BDMA) was prepared by free radical solution polymerization in aqueous media. Water uptake and dye sorption properties of polyelectrolyte AAm/AMPS hydrogels and AAm/AMPS/Bent composite hydrogels were investigated as a function of composition to find materials with swelling and sorption properties. FTIR analyses were made. Swelling experiments were performed in water and dye solution at 25°C, gravimetrically. Highly swollen AAm/AMPS and AAm/AMPS/Bent hydrogels were used in experiments on sorption of water‐soluble monovalent cationic dye such as Lauths violet “LV, (Thionin).” Swelling of AAm/AMPS hydrogels was increased up to 1,920–9,222% in water and 867–4,644% in LV solutions, while AAm hydrogels swelled 905% in water and swelling of AAm/AMPS/Bent hydrogels was increased up to 2,756–10,422% in water and 1,200–3,332% in LV solutions, while AAm/Bent hydrogels swelled 849% in water. Some swelling kinetic and diffusional parameters were found. Water and LV diffusion into hydrogels was found to be non‐Fickian in character. For sorption of cationic dye, LV into AAm/AMPS and AAm/AMPS/Bent hydrogel was studied by batch sorption technique at 25°C. The amount of the dye sorbed per unit mass removal effiency and partition coefficient of the hydrogels was investigated. The influence of AMPS content in the hydrogels to sorption was examined. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Morphologies and applied properties of PSI/PA composite particles synthesized at low temperature
Authors: Wu Yumin , Ge Chengyue , Xu Jun , Bi Jianmei , Chen Qingfen 
Published: April 2008

AbstractLatex with a poly(dimethyl‐siloxane) core and a poly(methylmethacrylate‐ butylacrylate‐ 2‐hydroxypropyl acrylate) shell have been prepared at low temperature with potassium‐persulphate (KPS), sodium formaldehyde sulfoxylate (SFS) and 2,2′‐azobis [2‐(2‐imidazolin‐ 2‐yl)propane] dihydrochloride (VA‐044) as composite initiators by staged emulsion polymerization. Reactive surfactants were used to significantly improve the applied properties such as water adsorption ratio and thermo‐properties. Transmission electron microscopy (TEM) results indicated that increasing the amount of 2‐hydroxypropyl acrylate (HPA) and butylacrylate (BA) was favorable to form the core/shell particles. Particle size distribution results showed with increasing the dosages of surfactants, initiators, and seed‐latex, particle size decreased. Differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA) results indicated the high temperature‐reserved of copolymer was improved in the presence of polysiloxane. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers
Studies on mechanical properties of sisal fiber/phenol formaldehyde resin in‐situ composites
Authors: Mu Qiuhong , Wei Chun , Feng Shengyu 
Published: April 2008

AbstractPhenol formaldehyde resin (PF) reinforced with short sisal fibers (SF) were obtained by two methods, direct‐mixing and polymerization filling. Impact and bending properties of resulting composites were compared. Under the same compression molding conditions, polymerization filled composites showed better mechanical properties than those of direct‐mixed composites. The influences of fiber modifications on the mechanical properties of SF/PF in‐situ (polymerization filled) composites have been investigated. Treated‐SF‐reinforced composites have better mechanical properties than those of untreated‐SF‐reinforced composites. The effects of SF on water absorption tendencies of SF/PF composites have also been studied. In addition, sisal/glass (SF/GF) hybrid PF composites of alkali‐treated SF were prepared. Scanning electron microscopic studies were carried out to study the fiber‐matrix adhesion. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Three‐dimensional fiber orientation in vibration welded joints of glass fiber reinforced polyamide‐6
Authors: Kamal Musa R. , Chung Young‐Mi , Gomez Rodolfo 
Published: April 2008

AbstractA technique was developed to obtain the three‐dimensional distribution of fiber orientation in vibration‐welded joints of polyamide‐6 (PA‐6) reinforced with 30 wt% glass fibers. The heat‐affected zone (HAZ) of fiber‐reinforced PA‐6 was successfully revealed by polishing and etching the vibration welded joints. Examination with the polarized light microscope in the reflection mode showed detailed microstructure domains, including the bulk crystalline zone and the HAZ. Experimental elliptical fiber cross‐section images were used to obtain second order orientation tensors, thus providing a quantitative description of the three‐dimensional fiber orientation distribution. The fibers in the HAZ were reoriented towards the squeeze flow direction, when compared with the bulk phase. Low welding pressure does not necessarily produce a more favorable fiber orientation in the tensile direction than high welding pressure. High welding pressure and low amplitude promote fiber reorientation in both the squeeze flow and tensile (weld thickness) directions. Overall, it was found that, at 30% fiber content, vibration‐welded joints of injection molded fiber‐reinforced PA‐6 are weaker than vibration‐welded joints in unreinforced injection molded samples. The fibers in the former do not undergo sufficient reorientation to influence weld strength in the tensile direction. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers
Crystal morphology, melting behaviors and isothermal crystallization kinetics of SCF/PTT composites
Authors: Run Mingtao , Song Hongzan , Wang Sujuan , Bai Libin , Jia Yinghua 
Published: April 2008

AbstractIsothermal crystallization kinetics, subsequent melting behavior, and the crystal morphology of short carbon fiber and poly(trimethylene terephthalate) composites (SCF/PTT) were investigated by using differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The crystal morphology of the composites isothermally crystallized at Tc = 205°C is predominantly banded spherulites observed under polarizing micrographs, while the pattern of banded spherulites changed from ring to serration as the SCF content added into the PTT. Moreover, nonbanded spherulites formed at Tc = 180°C. The commonly used Avrami equation was used to fit the primary stage of the isothermal crystallization. The Avrami exponents n are evaluated to be 1.6–2.0 for the neat PTT and 2.7–3.0 for SCF/PTT composites, and the SCF acting as nucleation agents in composites accelerates the crystallization rate with decreasing the half‐time of crystallization and the sample with SCF component of 2% has the fastest crystallization rate. The crystallization activation energy calculated from the Arrhenius formula suggests that the adding SCF component improved the crystallization ability of the PTT matrix greatly, and the sample with of 2% SCF component has the most crystallization ability. Subsequent melting scans of the isothermally crystallized composites all exhibited triple melting endotherms, in which the more the component of SCF, the lower temperature of the melting peak, indicating the less perfect crystallites formed in those composites. Furthermore, the melting peaks of the same sample are shifted to higher temperature with increasing Tc, suggesting the more perfect crystallites formed at higher Tc. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Interfacial interactions and performance of polyamide 6/modified attapulgite clay nanocomposites
Authors: Pan Bingli , Ren Junfang , Yue Qunfeng , Liu Bin , Zhang Junyan , Yang Shengrong 
Published: April 2008

AbstractAttapulgite (AT) clay was firstly treated with sodium polyacrylate (PAS), then polyamide 6 (PA6)/AT nanocomposites were prepared by simple melt compounding. Transmission electron microscope (TEM) and Fourier transform infrared spectrometry (FT‐IR) of treated AT confirm the success of purifying and surface modification of the original AT by PAS. X‐ray diffraction spectra for the nanocomposites show that the microstructure of AT in PA6 matrix is almost unchanged. It indicates that a strong interfacial adhesion exists between AT and PA6 matrix through analyzing fracture surfaces of the nanocomposites, the variation of glass transition temperature (Tg) obtained by dynamic mechanical analysis, and interfacial interaction factors; field emission scanning electron microscopy on the fracture surfaces of the nanocomposites shows that a uniform dispersion of AT is obtained. The above two aspects conform to the improvement of mechanical and thermal properties of the nanocomposites. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Structure and flammability properties of NR‐organoclay nanocomposites
Authors: Liu Lan , Jia Demin , Luo Yuanfang , Li Bo 
Published: April 2008

AbstractThe nanocomposites of natural rubber (NR) and organoclay modified by tributyl phosphate (TMMT) were prepared by the mixing intercalation method and the structure and the flammability properties of them were studied. The structure of the NR‐TMMT nanocomposites were characterized by X‐ray diffraction, transmission electron microscopy, fourier transform infrared spectroscopy and the results show that the d‐spacing of TMMT increase substantially with tributyl phosphate addition and the layers of TMMT disperse in rubber matrix on a nanometer scale. The flammability properties of them were demonstrated by cone calorimeter and indicate that the NR‐TMMT nanocomposites have significantly decreased in heat release rate, mass loss rate, and smoke produce rate. The NR‐TMMT nanocomposites appears very good the flame retardant properties. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Influence of wood flour loading on tribological behavior of epoxy composites
Authors: Dwivedi U.K. , Chand Navin 
Published: April 2008

AbstractA series of wood flour (WF) filled epoxy composites consisting of five samples were prepared by varying the concentration of WF in step of 10 wt%. These samples were characterized for its wear behavior in abrasive and sliding wear modes to study the influence of WF. It was observed that specific wear rate (k0) of all the composites decreased with increasing load in sliding wear mode. Specific wear rate was of the order of 10−10 m3/Nm in abrasive wear mode and ∼10−14 m3/Nm in sliding wear mode. Composite containing 40 wt% WF exhibited the lowest specific wear rate in abrasive wear mode. While composite containing 20 wt% WF exhibited lowest specific wear rate in sliding wear mode. This was attributed to the fact that in abrasive wear mode, the wear debris consisting of mainly WF particles was maximum for 10 wt% composite and minimum for 40 wt% composite. In sliding wear mode, the exposed WF particles caused maximum roughening of steel counterface in the case of composite containing higher concentration of WF particles. Hence, they exhibited a higher value of specific wear rate. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers
Effect of surface‐modification on the dynamic behaviors of fly ash cenospheres filled epoxy composites
Authors: Gu Jian , Wu Gaohui , Zhao Xiao 
Published: April 2008

AbstractAn inexpensive fly ash (FA), which is from a waste production, has been used as the filler to prepare the epoxy composites. With the purpose of characterizing the effect of surface‐modification on the dynamic behaviors of FA cenospheres/epoxy composites, Fourier transform infrared spectral analysis (FTIR), microstructure observation as well as dynamic mechanical analysis (DMA) were systematically investigated, respectively. At the same time, the impact toughness was also evaluated by impact property testing. With FTIR analysis, it can be found that the functionalized groups exist on the surface of FA cenospheres. The SEM photographs show that the FA cenosphere particulates with surface‐modification are distributed homogeneously and have a good interface bonding with the matrix, and the ruptures occur not in the two phases interface, but in the middle parts of FA cenospheres after impact. In addition, DMA indicates that the composite filled with surface‐modified FA cenospheres has a wider glass transition temperature region and a higher loss factor, and its relatively higher impact toughness can also be revealed through impact property test. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Exercise‐induced changes in respiratory impedance in young wheezy children and nonatopic controls
Authors: Malmberg L. Pekka , Mäkelä Mika J. , Mattila Petri S. , Hammarén‐Malmi Sari , Pelkonen Anna S. 
Published: April 2008

AbstractExercise‐induced bronchoconstriction (EIB) is a specific sign of active asthma, but its assessment in young children may be difficult with lung function techniques requiring active cooperation. The aim of the study was to assess the normal pattern of exercise‐induced responses of respiratory impedance by using impulse oscillometry (IOS), and to investigate how these responses discriminate wheezy children from control subjects. IOS measurements were performed in a consecutive sample of wheezy children aged 3–7 years (n = 130) and in an aged matched control group of nonatopic children without respiratory symptoms (n = 79) before and after a free running test. After exercise, wheezy children showed significantly larger responses in respiratory resistance (Rrs5), reactance (Xrs5), and the resonance frequency (Fr) than the control subjects. In the control group, the upper 95% confidence limit of the maximal change was 32.5% for Rrs5, 85.7% for Xrs5, and 53.1% for Fr. By using analysis of receiver operating characteristics, the change in Rrs5 distinguished the wheezy children from the control subjects more effectively than change in Xrs5 or Fr. In wheezy children, the response was significantly effected by the outdoor temperature and exercise intensity in terms of maximum heart rate. In conclusion, an increase of 35% in Rrs5 after a free running test can be regarded as an abnormal response. Wheezy children show an enhanced airway response, which is clearly distinguishable from the control subjects. IOS is a feasible method to detect EIB in young children. Pediatr Pulmonol. 2008; 43:538–544. © 2008 Wiley‐Liss, Inc.
A randomized, controlled trial of smoking cessation counseling provided during child hospitalization for respiratory illness
Authors: Ralston Shawn , Roohi Mahshid 
Published: April 2008

AbstractThe impact of parental smoking on children is enormous. Injury and illness related to parental smoking result in 6,200 excess pediatric deaths per year, which places smoking as the leading preventable cause of death in US children. Parental smoking doubles the risk of child hospitalization for respiratory illness therefore pediatricians have frequent contact with smoking parents. A single study has previously investigated the effect of child hospitalization on parental smoking cessation.Smoking caregivers of children hospitalized for respiratory illness at the University of New Mexico were offered a smoking cessation intervention during the child's hospitalization. Participants were randomized to receive either a brief anti‐smoking message or more extensive counseling based on current clinical practice guidelines.Forty‐two parents enrolled in the study. Fourteen percent of participants in the counseling group and 5% in the brief message group were self‐reported quitters at 6 months.A significant percentage of smoking parents of children hospitalized for respiratory illness are willing to receive smoking cessation counseling while their child is in the hospital. Abstinence rates appear similar to other pediatric office‐based interventions. Child hospitalization should be considered an important opportunity to provide parents with smoking cessation services, particularly since many smoking parents will not have access to these services elsewhere. Pediatr Pulmonol. 2008; 43:561–566. © 2008 Wiley‐Liss, Inc.
Structural and functional characterization of a novel phosphatase from the Arabidopsis thaliana gene locus At1g05000
Authors: Aceti David J. , Bitto Eduard , Yakunin Alexander F. , Proudfoot Michael , Bingman Craig A. , Frederick Ronnie O. , Sreenath Hassan K. , Vojtik Frank C. , Wrobel Russell L. , Fox Brian G. , Markley John L. , Phillips George N. 
Published: April 2008

AbstractThe crystal structure of the protein product of the gene locus At1g05000, a hypothetical protein from A. thaliana, was determined by the multiple‐wavelength anomalous diffraction method and was refined to an R factor of 20.4% (Rfree = 24.9%) at 3.3 Å. The protein adopts the α/β fold found in cysteine phosphatases, a superfamily of phosphatases that possess a catalytic cysteine and form a covalent thiol‐phosphate intermediate during the catalytic cycle. In At1g05000, the analogous cysteine (Cys150) is located at the bottom of a positively‐charged pocket formed by residues that include the conserved arginine (Arg156) of the signature active site motif, HCxxGxxRT. Of 74 model phosphatase substrates tested, purified recombinant At1g05000 showed highest activity toward polyphosphate (poly‐P12‐13) and deoxyribo‐ and ribonucleoside triphosphates, and less activity toward phosphoenolpyruvate, phosphotyrosine, phosphotyrosine‐containing peptides, and phosphatidyl inositols. Divalent metal cations were not required for activity and had little effect on the reaction. Proteins 2008. © 2008 Wiley‐Liss, Inc.
Single and multiple input modules in regulatory networks
Authors: Konagurthu Arun S. , Lesk Arthur M. 
Published: April 2008

AbstractInteractions between transcription factors and target genes form regulatory networks that control target gene expression. Regulatory networks contain canonical motifs, including the feed forward loop (FFL), single input module (SIM), and multiple input module (MIM) (Fig. 1). A challenge for network analysis is to identify and enumerate the motifs, required to illuminate their biological significance. Although there is consensus about the definition of the FFL, published definitions of the SIM and MIM are unclear and often used inconsistently. Here, we provide, for the first time, a complete and consistent definition of SIM and MIM, and algorithms for enumerating SIMs and MIMs in any network. From the algorithmic point of view, enumeration of SIMs and MIMs is substantially harder than enumerating FFLs. We compare the distributions of motifs in the Yeast regulatory network under different physiological conditions, reported earlier by the landmark paper of Luscombe et al. (Nature 2004, 431: 308–312). Our reanalysis shows major differences in the number of motifs compared with the results of those authors, requiring significant revision of some of their conclusions. Proteins 2008. © 2008 Wiley‐Liss, Inc.
Crystal structure of DFA0005 complexed with α‐ketoglutarate: A novel member of the ICL/PEPM superfamily from alkali‐tolerant Deinococcus ficus
Authors: Liao Cheng‐Jen , Chin Ko‐Hsin , Lin Chao‐Hsiung , Tsai Peter Shi‐Fong , Lyu Ping‐Chiang , Young Chiu‐Chung , Wang Andrew H.‐J. , Chou Shan‐Ho 
Published: April 2008

AbstractThe crystal structure of the DFA0005 protein complexed with α‐ketoglutarate (AKG) from an alkali‐tolerant bacterium Deinococcus ficus has been determined to a resolution of 1.62 Å. The monomer forms an incomplete α7/β8 barrel with a protruding α8 helix that interacts extensively with another subunit to form a stable dimer of two complete α8/β8 barrels. The dimer is further stabilized by four glycerol molecules situated at the interface. One unique AKG ligand binding pocket per subunit is detected. Fold match using the DALI and SSE servers identifies DFA0005 as belonging to the isocitrate lyase/phosphoenolpyruvate mutase (ICL/PEPM) superfamily. However, further detailed structural and sequence comparison with other members in this superfamily and with other families containing AKG ligand indicate that DFA0005 protein exhibits considerable distinguishing features of its own and can be considered a novel member in this ICL/PEPM superfamily. Proteins 2008. © 2008 Wiley‐Liss, Inc.
Pulsed layer growth of AlInGaN nanostructures
Authors: Jetter Michael , Michler Peter 
Published: April 2008

AbstractA pulsed layer growth mode in the metal‐organic vapor phase epitaxy (MOVPE) was used to fabricate excellent quality AlInGaN nanostructures. The amount of material was varied, resulting in AlInGaN layer thicknesses between nominally 1.5 nm and 6 nm, respectively. We have analyzed the material properties by X‐ray diffraction (XRD) as well as photoluminescence (PL) spectroscopy. The observed XRD‐spectra and the PL intensity show the high quality of the deposited material.By analyzing the PL spectra we have found an energetic shift of the resonance lines from 2.65 eV to 3.33 eV with decreasing well thickness. We attribute this shift mainly to the presence of internal electric fields at the AlIn‐GaN/GaN interface. Power‐dependent and time resolved PL experiments confirm this observation. Comparing the luminescence at elevated temperatures, the pulsed layer epitaxy structures reveal a much higher intensity as the conventional grown samples. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Power AlGaN/GaN HFETs with excellent Vb/Ron for high speed switching
Authors: Ikeda Nariaki , Kato Kazuo , Li Jiang , Kaya Syusuke , Nomura Takehiko , Masuda Mitsuru , Yoshida Seikoh 
Published: April 2008

AbstractAlGaN/GaN HFETs with a large current and a high breakdown voltage were fabricated. We examined the switching characteristics and capacitance parameters such as an input capacitance (Ciss), a reverse transfer capacitance (Crss), a gate to a source charge (Qgs) and a gate to a drain charge (Qgd) using the GaN HFET devices. In order to confirm the advantage for the high‐frequency switching operation of the GaN HFETs compared with Si devices, capacitance parameters and the figure of merit (FOM) Vb/(Ron) for a switching capability were examined. As a result, a low Ciss, Crss, and Qg were obtained and the FOMs of GaN HFETs have one order of magnitude larger than those of Si power devices. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)