bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of nanoclay particles on mold‐filling performance in composites made via resin infusion process
Authors: Karimzadeh M. , Sabet A.R. , Beheshty M.H. 
Published: April 2012

AbstractThis study investigates the effect of 3 and 5 wt% nanoclay (Cloisite 30B) addition on mold filling time and performance of continuous glass filament mat reinforced unsaturated polyester (UP) resin composites made by vacuum infusion process. X‐ray diffraction and transmission electron microscopy analysis as well as viscosity change in liquid state resin confirmed intercalation and exfoliation of the nanoclay in the resin system. The result shows mold filling time increase of 3 and 2.4 times for the samples containing 3 and 5 wt% nanoclay, respectively, compared with nanoclay‐free sample. This increase in mold filling time is directly attributed to the increase in resin viscosity. Filtration of nanoclay particles were observed in the resin flow direction. Result showed 8 and 14% filtration of nanoclay in flow direction for the samples with 3 and 5 wt% nanoclay content, respectively. Nanoclay containing specimens prepared from near resin entry port area showed relatively higher flexural and tensile modulus and as well as strength compared to specimens prepared from area close to vacuum port area. The result showed best performance for 3 wt% nanoclay containing specimen. However, impact strength decreased about 6.1 and 10.8% for 3 and 5% nanoclay, respectively. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Experimental investigation on reprocessing of extruded wood flour/HDPE composites
Authors: Shahi Peyman , Behravesh Amir Hossein , Daryabari Seyyed Yaser , Lotfi Maziar 
Published: April 2012

AbstractThis article presents an experimental study on the change in the properties of wood–plastic composites (WPCs) when reprocessed. The degree of properties degradation upon reprocessing, for recycling purpose, can be considered as a key factor to choose an alternative against discarding into the environment. A material which retains its properties when recycled, or at least exhibits insignificant reduction in its properties, is favorable in environmental point of view. To investigate the reprocessing effect on the WPC properties, in this study, cylindrical profiles of WPC, with 60 wt% of wood content, were produced using a twin screw extruder, at first stage (virgin WPC). These profiles were then chopped into granules and used in the reproduction of the same shaped product (recycled WPC). For the measurement of mechanical properties, tensile and three‐point bending tests were conducted. Differential scanning calorimetry (DSC) test was performed to compare thermal behavior of the neat HDPE, virgin and recycled composites. Scanning electron microscopy (SEM) images were also produced to observe the adhesion quality of the components and changes in wood particles size. Physical properties such as density and water uptake were also measured. A reduction in strength was observed upon recycling which was accompanied with the decrease in density, while an increase in the flexural modulus was noticed. The results also indicate that the recycled samples exhibit a higher water uptake. Analysis of thermal behavior showed a slight increase in the melting temperature of the reprocessed composite and decrease in the degree of crystallinity especially at the first stage of the HDPE process. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Isolation and characterization of betel nut leaf fiber: Its potential application in making composites
Authors: Arifuzzaman Khan G.M. , Shahrear Palash S.R. , Shamsul Alam M. , Chakraborty A.K. , Gafur M.A. , Terano M. 
Published: April 2012

AbstractBetel nut leaf fiber (BNLF) is a new finding as cellulosic filler for polymer composites. Its main constituents are 75% α‐cellulose, 12% hemicelluloses, 10% lignin, and 3% others matter, viscosity average molecular weight 132,000 and degree of crystallinity 70%. In the present work, BNLF reinforced polypropylene (PP) composites were prepared using heat press molding method. 5–20 wt% short length fiber is taken for getting benefits of easy manufacturing and the fiber was chemically treated with NaOH, dicumyl peroxide (DCP), and maleic anhydride‐modified PP (MAPP) to promote the interfacial bond with PP. The extent of modification of fiber was assessed on the basis of morphology, bulk density, moisture absorption, thermal, and mechanical properties of untreated fiber, treated fiber, and their reinforcing PP composites. The tensile and flexural strength of composites increase with the increase of fiber loading up to 10 and 20 wt%, respectively. It was also observed that Young's modulus and flexural modulus increase with fiber loading. The thermal degradation behavior of resulting composites was investigated. Among the various treated fibers, MAPP‐treated fiber composite showed best interfacial interactions as well as mechanical and thermal properties. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Novel trifluoromethylated epoxy based thermosets: synthesis and characterization
Authors: Penoff Marcela E , Montemartini Pablo E , Oyanguren Patricia A 
Published: April 2012

AbstractTwo series of trifluoromethylated crosslinked epoxy‐based polymers with different molecular architectures and fluorine contents (from 1 to 5 wt%) have been investigated. The epoxy monomer was a diglycidyl ether of bisphenol A, and the curing agents were 3‐(trifluoromethyl)aniline and 4,4′‐methylenebis(3‐chloro‐2,6‐diethylaniline). The structural parameters of networks such as gelation and vitrification and the properties of the resulting fluorinated materials were investigated and compared. Final materials showed high transparency with an ultraviolet‐visible absorption cut‐off between 350 and 380 nm, low moisture (0.60 wt%) and a decrease in dielectric constant from 6.3 to 5.2 with increasing fluorine content. Copyright © 2012 Society of Chemical Industry
Synthesis and conformation effects of poly(phenylacetylene)s having chiral and racemic polylactide pendants
Authors: Zhang Chunhong , Wang Hailun , Su Guangdong , Li Ruiqi , Shen Xiande , Zhang Shuang , Geng Qianqian , Liu Fangbin , Otsuka Issei , Satoh Toshifumi , Kakuchi Toyoji 
Published: April 2012

AbstractChiral and racemic macromonomers with a polymerizable phenylacetylenyl end group (PA‐PLLA and PA‐PDLLA) were successfully synthesized through living ring‐opening polymerization of chiral and racemic monomers (L‐lactide and DL‐lactide), respectively. Then the homopolymerization of PA‐PLLA and PA‐PDLLA was successfully carried out to give poly(PA‐PLLA) and poly(PA‐PDLLA), respectively. Chiroptical properties, hydrodynamic radii and micromorphologies of poly(PA‐PLLA) and poly(PA‐PDLLA) were analyzed via circular dichroism, dynamic light scattering and atomic force microscopy (AFM), and the conformation of the polymers is discussed. The results indicate that poly(PA‐PLLA) induced Cotton effects with different intensities in various solvents, and its hydrodynamic radii and dispersity were also different in various solvents, while poly(PA‐PDLLA) induced no Cotton effects and its hydrodynamic radii and dispersity were approximately the same in various solvents. Furthermore, a helical conformation of poly(PA‐PLLA) and the random main chains of poly(PA‐PDLLA) were observed by AFM. Therefore, it is concluded that poly(PA‐PLLA) possesses a dynamic one‐handed helical conformation in various solvents due to chiral poly(L‐lactide) pendants, while poly(PA‐PDLLA) possesses racemic main chains because of the racemic poly(DL‐lactide) pendants. Copyright © 2012 Society of Chemical Industry
Estimation of Agglomeration Degree and Nanoparticles Shape of Zirconia Nanopowders
Authors: Danilenko Igor , Konstantinova Tetyana , Pilipenko Nikolay , Volkova Galina , Glasunova Valentina 
Published: April 2012

AbstractThe influence of different surfactants (Trilon B, Polyammoniumacrylate and Neonol) and mineralizers (HCl, KOH, CH3COOH, etc.) on agglomeration degree of zirconia nanopowders obtained by precipitation technique was investigated. By adding of surfactants and mineralizers the different phase composition, particle size and agglomeration degree of zirconia nanopowders were obtained. The comparison between experimental specific surface area (SSA) value and calculated surface area for nonagglomerated spherical particle model show that experimental value of SSA bigger than calculated value. We proposed that low calcining temperatures (less than 700 °C) lead to formation the zirconia particles with cylindrical form. When taking into account the contact area between the particles in this model, we recalculate the surface area of powders and get better fit to experimental value.
Characterization of Different Shaped Nanocrystallites using X‐ray Diffraction Line Profiles
Authors: Li Zongquan 
Published: April 2012

AbstractQuantitative information on the X‐ray diffraction line profiles for different shaped nanocrystallites, using nanocrystalline Cu as an example, are obtained by using the Debye scattering equation, which is useful for characterizing nanocrystallite. The apparent lattice parameter obtained from line positions by using the Bragg's law has a larger deviation from the actual value when the crystallite sizes are smaller than about 10nm. When the crystallites are larger than about 6nm, the full width at half maximum (FWHM) ratios of FWHMhkl to FWHM002 are nearly constants which can be used to identify the shape of the crystallites. The Scherrer constant depends not only on the shape of the crystallite but also on the Miller index of the line, the values of the Scherrer constant for different shaped nanocrystallites are given in the present paper.
Characterization of Powders using Micro Computed Tomography
Authors: Redenbach Claudia , Ohser‐Wiedemann Renate , Löffler Ralf , Bernthaler Timo , Nagel Alwin 
Published: April 2012

AbstractMicro computed tomography (μCT) is proposed as a tool for the characterization of powders. Using this technique three dimensional images carrying the whole spatial information on a particular powder can be obtained. After an image analytic separation of the single particles, distributions of geometric characteristics describing size, shape, and spatial arrangement of the particles can be estimated. The method is applied to four samples of powders with different particle structure. The results are compared with particle size characteristics measured by laser diffraction, sieve analysis, and the analysis of microscopic 2D images.
Understanding the inactivation process of organophosphorus herbicides: A DFT study of glyphosate metallic complexes with Zn2+, Ca2+, Mg2+, Cu2+, Co3+, Fe3+, Cr3+, and Al3+
Authors: Caetano Melissa S. , Ramalho Teodorico C. , Botrel Douglas F. , da Cunha Elaine F. F. , de Mello Walclee Carvalho 
Published: April 2012

AbstractGlyphosate is the active component of one of the top‐selling herbicides, which is also a potent EPSP synthase inhibitor. The herbicide is absorbed by living tissue and translocated via the phloem, to plant roots and rhizomes. When applied directly into the soil it has low activity, due to the high adsorption by soil constituents. Understanding the specific interactions between metals in the soil and glyphosate is the main step in understanding the low activity of the herbicide when applied directly into the ground and not pulverized. We can observe there is a stability order for both tetrahedral and octahedral complexes between glyphosate and metals: Zn>Cu>Co>Fe>Cr>Al>Ca>Mg. © 2012 Wiley Periodicals, Inc.
Theoretical study of free and encapsulated carboxylic acid and amide dimers
Authors: Tzeli Demeter , Petsalakis Ioannis D. , Theodorakopoulos Giannoula , Ajami Dariush , Rebek Julius 
Published: April 2012

AbstractThe homodimers and heterodimers of four carboxylic acids RCOOH and four amides RCONH2, where R = H, methyl, phenyl, p‐ethylphenylene have been calculated via DFT(M06‐2X), MP2, and CCSD(T) methods in conjunction with the 6‐31G(d,p), 6‐311+G(d,p), aug‐cc‐pVTZ, and aug‐cc‐pVQZ basis sets to find out how the substituent R influences their dimerization energy (ΔE) and their hydrogen bond length. The calculated ΔE values range from 14 to 17 kcal/mol for the different dimers in the gas phase, with the ordering carboxylic homodimers ≥ amide‐carboxylic dimers > amide homodimers. The M06‐2X/6‐311+G(d,p) geometries and ΔE values are in very good agreement with the corresponding MP2/aug‐cc‐pVQZ and CCSD(T)/aug‐cc‐pVTZ values. Coencapsulation of the dimers was studied to examine its effect on the calculated bond lengths and strength of the hydrogen bonds at the M06‐2X/6‐31G(d,p) level of theory. The experimental and calculated % distributions of the encapsulated dimers, taking into account statistical factors are in good agreement. © 2012 Wiley Periodicals, Inc.
Why sp2‐like nanosilicons should not form: Insight from quantum chemistry
Authors: Sheka E. F. 
Published: April 2012

AbstractThe odd‐electron molecular theory, which takes into account the electron correlation, has been applied for a comparative consideration of sp2 nanocarbons and their siliceous analogues. Four characteristic quantities that involve the energy misalignment, the number of effectively unpaired electrons, the squared spin value, and CC and SiSi chemical bond lengths have been suggested to classify the extent of the odd electron correlation in both families. Providing a considerable enlargement of the internuclear distances, the electron correlation in siliceous species is extremely strong thus resulting in complete radicalization of the species and proving the impossibility of their existence at ambient conditions in contrast to carboneous ones that are not so strong correlated. © 2012 Wiley Periodicals, Inc.
One‐electron pseudopotential study of the alkali hydride cation NaH+: Structure, spectroscopy, transition dipole moments, and radiative lifetimes
Authors: Berriche H. 
Published: April 2012

AbstractThe structure and spectroscopic properties of the ground and the lowest excited electronic states of the alkali hydride cation NaH+ have been investigated using an ab initio approach. In this approach, a nonempirical pseudopotential for the Na+ core has been used and a core–core and a core‐valence correlation corrections have been added. The adiabatic potential energy curves and the molecular spectroscopic constants for numerous electronic states of 2Σ+, 2Π, and 2Δ symmetries, dissociating up to Na (4d) + H+ and Na+ + H (3d), have been calculated. As no experimental data are available, we discuss our results by comparing with the available theoretical calculations. A satisfying agreement has been found for the ground state with previous works. However, a clear disagreement between this study and the model potential work of Magnier (Magnier, J. Phys. Chem. A 2005, 109, 5411) has been observed for several excited states. Numerous avoided crossings between electronic states of 2Σ+ and 2Π symmetries have been found and analysed. They are related to the interaction between the potential energy curves and to the charge transfer process between the two ionic systems Na+H and NaH+. Furthermore, we provide an extensive set of data concerning the transition dipole moments from X2Σ+ and the 22Σ+ states to higher excited states of 2Σ+ and 2Π symmetries. Finally, the adiabatic potential energy curves of the ground (X2Σ+) and the first (22Σ+) excited states and the transition dipole moments between these states are used to evaluate the radiative lifetimes for the vibrational levels of the 22∑+ state for the first time. In addition to the bound–bound contribution, the bound‐free term has been evaluated and added to the total radiative lifetime. © 2012 Wiley Periodicals, Inc.
A theoretical study on the hydrogen transport mechanism in SrTiO3 perovskite. II. Scandium doping at titanium site
Authors: Onishi Taku , Helgaker Trygve 
Published: April 2012

AbstractHybrid Kohn–Sham calculations are performed to clarify the proton‐conduction mechanism in Sc‐doped SrTiO3 perovskite, from the viewpoint of energetics and bonding. The calculated potential energy curves are discussed and a molecular‐orbital analysis performed. Much hydrogen can exist around doped scandium, where it is energetically stabilized. However, scandium‐doping has no energetic advantage in the activation energy for proton‐conduction. © 2012 Wiley Periodicals, Inc.
Study of the mass spectrometric behaviors of anthocyanins in negative ionization mode and its applications for characterization of anthocyanins and non‐anthocyanin polyphenols
Authors: Sun Jianghao , Lin Long‐ze , Chen Pei 
Published: April 2012

RATIONALETraditionally, anthocyanin analysis in mass spectrometry is carried out in the positive ionization mode only. A study of the mass spectrometric behaviors of anthocyanins in the negative ionization mode revealed interesting characteristics that was not previously reported. It can be used to differentiate anthocyanins from other non‐anthocyanin polyphenols.METHODSAn ultra‐high‐performance liquid chromatography with high‐resolution mass spectrometry (U‐HPLC/HRMS) method was developed. The method used multiple‐stage mass fragmentation in both the negative and positive ion modes. The whole cycle time of the new method is 1.8 s for two full scans and six data‐dependent scans.RESULTSThe new strategy found, in the negative ionization mode, a series of characteristic ions, e.g. [M–2H]–, [M–2H + H2O]– , formic acid adducts, and doubly charged ions were observed for the MS analysis of anthocyanins. The characteristic ions can be used for identification and differentiation of anthocyanins and non‐anthocyanin phenolic compounds. Comprehensive studies were performed on the differentiation of anthocyanins and non‐anthocyanin polyphenols in blueberry (Vaccinium cyanococcus), Hongcaitai (Brassica compestris L. var. purpurea Bailey), and red radish (Raphanus sativus var. longipinnatus 'Shinrimei').CONCLUSIONSThe data generated from a single LC run enables rapid and reliable differentiation and identification of anthocyanins and non‐anthocyanins in botanicals and foods. Published 2012. This article is a US Government work and is in the public domain in the USA.
Proactive recovery approach for intrusion tolerance with dynamic configuration of physical and virtual replicas
Authors: Zhao Feng , Li Min , Qiang Weizhong , Jin Hai , Zou Deqing , Zhang Qin 
Published: April 2012

ABSTRACTProactive recovery mechanism has been widely used in building intrusion‐tolerant systems that are able to tolerate an arbitrary number of faults. However, previous proactive recovery methods seldom consider the dynamic in attacking power that may cause the increase in fault rate, resulting unguaranteed service availability. This paper describes an approach for tolerating intrusions, or more precisely, damages to replicated data, through dynamic configuration of physical and virtual replicas, which follows a general approach called proactive recovery, and proposes to dynamically adjust recovery frequency to handle potentially changing fault rate. This dynamic proactive recovery method takes the dynamic changes of attaching power into consideration to avoid/minimize the effect of intrusions. Our method is especially effective and useful in intrusion tolerance with physical replicas: it dynamically provides virtual replicas during rejuvenation phase. Copyright © 2012 John Wiley & Sons, Ltd.
Network specific vulnerability based alert reduction approach
Authors: Njogu Humphrey Waita , Jiawei Luo , Kiere Jane Nduta 
Published: April 2012

ABSTRACTTraditional intrusion detection systems are known for triggering large volumes of alerts. An average commercial intrusion detection system reports thousands of alerts on daily basis. A large proportion of these alerts are false alerts. In the field of alert management, alert verification is cited as critical component in determining the success of intrusions. It helps to eliminate any alert that does not have a corresponding vulnerability in a network, hence improving the effectiveness of alert management approaches. Alert verification alone cannot guarantee alerts of high quality because the validated alerts may contain massive number of redundant alerts. The analysts who review alerts are likely to take longer time to understand the complete security incident because it would involve evaluating each single redundant alert. Consequently, the analysts would not only encounter difficulties when taking the correct decision but would also take longer time to respond against the intrusions. Therefore, the unnecessary alerts diminish the value and urgency of the relevant alerts.This paper seeks to address the aforementioned issue to strengthen the vulnerability‐based alert management approaches. Our approach verifies alerts prior to merging them. Central to this approach is the use of two components: verifier and alert merger. The verifier component improves the quality of alerts by validating them with enhanced vulnerability assessment data. The alert merger component reduces huge number of redundant alerts. Experiments conducted in our test bed have demonstrated the success of our approach in reducing most of the unnecessary alerts for a range of attacks with high accuracy yet closely maintaining the detection rate. Copyright © 2012 John Wiley & Sons, Ltd.
STaR: design and quantitative measurement of source‐location privacy for wireless sensor networks
Authors: Lightfoot Leron , Li Yun , Ren Jian 
Published: April 2012

AbstractWireless sensor networks (WSNs) can provide the world with a technology for real‐time event monitoring. One of the primary concerns that hinder the successful deployment of WSNs is source‐location privacy (SLP). The privacy of the source location is vital and highly jeopardized by the usage of wireless communications. Although message content privacy can be ensured through message encryption, it is much more difficult to adequately address the SLP. For WSNs, SLP service is further complex by the fact that sensors consist of low‐cost and energy‐efficient radio devices. Therefore, using computationally intensive cryptographic algorithms (such as public‐key cryptosystems) and large‐scale broadcasting‐based protocols are not suitable for WSNs. In this paper, we analyze the quantitatively measure source‐location information leakage in routing‐based SLP protection schemes for WSNs. Through this model, we identify vulnerabilities of some well‐known SLP protection schemes. We also propose a routing technique, called the Sink Toroidal Region (STaR), to provide adequate SLP with low energy consumption. With this routing technique, the source node randomly selects an intermediate node within a designed STaR area located around the sink node. Furthermore, this routing protocol ensures that the intermediate node is neither too close, nor too far from the sink node in relations to the entire network. While ensuring SLP, our simulation results show that the proposed scheme is very efficient and can be used for practical applications. Copyright © 2012 John Wiley & Sons, Ltd.