bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular orientation evolution during low‐density polyethylene blown film extrusion using real‐time Raman spectroscopy
Authors: Gururajan Giriprasath , Ogale Amod A.
Published: October 2008

Real‐time polarized Raman spectroscopy was used in this study to measure the molecular orientation evolution during blown film extrusion of low‐density polyethylene (LDPE). Spectra were obtained at different locations along the blown film line, starting from the molten state near the die and extending up to the solidified state near the nip rolls. The trans CC symmetrical stretching vibration of polyethylene (PE) at 1132 cm−1 was analyzed for films possessing uniaxial symmetry. For the given peak, the principal axis of the Raman tensor is coincident with the c‐axis of the orthorhombic crystal, and was used to solve a set of intensity ratio equations to obtain second (〈P2(cosθ)〉) and fourth (〈P4(cosθ)〉) moments of the orientation distribution function. The orientation parameters (P2, P4) were found to increase along the axial distance in the film line even past the frost‐line height (FLH). The P2 values also showed an increasing trend with crystalline evolution during extrusion, consistent with past observations that molecular orientation takes place even after the blown film diameter is locked into place. It was also found that the integral ratio (I1132/I1064) obtained from a single, ZZ‐back‐scattered mode can provide a reasonable estimate of molecular orientation. These results indicate the potential of real‐time Raman spectroscopy as a rapid microstructure monitoring tool for better process control during blown film extrusion. Copyright © 2008 John Wiley & Sons, Ltd.
The relaxations of temporal bond polarizabilities of methylviologen adsorbed on the Ag electrode by 514.5 nm excitation: a Raman intensity study
Authors: Fang Chao , Wu Guozhen
Published: October 2008

An algorithm to elucidate the temporal bond polarizabilities from the surface enhanced Raman (SERS) intensities was employed to the case of methylviologen (MV) adsorbed on the Ag electrode. This enables us to obtain the properties of its SERS mechanisms and the effect of its adsorption. The analysis shows that the charge transfer and electromagnetic mechanisms involving in this MV SERS system possess different relaxation times for its various temporal bond polarizabilities. The physics is that the process involved in the charge transfer mechanism will take longer time than that involved in the electromagnetic mechanism since it needs more time to redistribute the charges during relaxation. The time division between these two mechanisms is figured out to be around 3 ps for this system. Adsorption also enhances the relaxation of the temporal bond polarizabilities, in general. The adsorption effect is indicated by the temporal bond polarizabilities close to the final stage of relaxation. They are, in fact, the quantities parallel to the bond electronic densities in the molecular orbital (MO) concept. For comparison, the case of MV solid was also analyzed. Copyright © 2008 John Wiley & Sons, Ltd.
Trissarcosine barium(2 + ) dibromide—a new complex of N‐methylglycine
Authors: Trzebiatowska‐Gusowska Monika , Ga̧gor Anna , Baran Jan , Drozd Marek
Published: October 2008

We obtained a new complex containing sarcosine (CH3NH2+CH2COO−) and barium(2 + ) dibromide (TSBB) in 3:1 molar ratio, as well as its deuterated analog. Single‐crystal X‐ray diffraction measurements show that TSBB crystallizes in the monoclinic system, space group P2(1)/c. The unit cell parameters are as follows: a = 18.345(4) Å, b = 10.668(2) Å, c = 8.9212(18) Å, β = 91.86(3)°, and Z = 4. The structure was determined with final R1 = 0.0396 (for I > 2σI). The crystal possesses a pseudohexagonal symmetry down c axis showing the resemblance to the crystal structure of trissarcosine calcium chloride (TSCC). There are NHBr hydrogen bonds (HB) of six types. TSBB crystal undergoes a phase transition at 416 K (heating)–415 K (cooling) of continuous nature. The spectroscopic [Infrared (IR) and Raman] investigation of the crystal was performed at room temperature. The results are discussed with respect to the crystallographic data, as well as the results obtained for TSCC crystal. Copyright © 2008 John Wiley & Sons, Ltd.
Structural studies and Raman spectroscopy of forbidden zone boundary phonons in Ni‐doped ZnO ceramics
Authors: Yadav Harish Kumar , Sreenivas K. , Gupta Vinay , Katiyar R. S.
Published: October 2008

We present X‐ray diffraction and Raman spectroscopy studies of Ni‐doped ZnO (Zn1−xNixO, x = 0.0, 0.03, 0.06, and 0.10) ceramics prepared by solid‐state reaction technique. The presence of the secondary phase along with the wurtzite phase is observed in Ni‐doped ZnO samples. The E2(low) optical phonon mode is seen to be shifted to a lower wavenumber with Ni incorporation in ZnO and is explained on the basis of force‐constant variation of ZnO bond with Ni incorporation. A zone boundary phonon is observed in Ni‐doped samples at ∼130 cm−1 which is normally forbidden in the first‐order Raman scattering of ZnO. Antiferromagnetic ordering between Ni atoms via spin‐orbit mechanism at low temperatures (100 K) is held responsible for the observed zone boundary phonon. Copyright © 2008 John Wiley & Sons, Ltd.
Raman characterization before and after rapid thermal annealing of CeO2 thin films grown by rf sputtering on (111) Si
Authors: Guhel Y. , Ta M. T. , Bernard J. , Boudart B. , Pesant J. C.
Published: October 2008

We investigated by Raman spectroscopy (RS) the crystalline quality of CeO2 thin films radio frequency magnetron sputtered on n‐type (111) Si substrates from CeO2 target. The deposition temperature was in the range of 200–800 °C. We also realized structural investigations on CeO2 layers after Rapid Thermal Annealing (RTA) performed in the range of 750–1000 °C for 30 s under nitrogen atmosphere. So this study displays that a high‐growth temperature and a high post‐growth‐RTA temperature improves the crystalline structure of the film.

In fact, the best crystalline quality, which is close to the CeO2 target taken as a reference, is obtained for a CeO2 layer deposited at 800 °C and post‐annealed at 1000 °C for 30 s. Copyright © 2008 John Wiley & Sons, Ltd.
Fast adsorption and separation of bovine serum albumin and lysozyme using micrometer‐sized macromesoporous silica spheres
Authors: Zhai Zheng , Wang Yujun , Chen Yang , Luo Guangsheng
Published: October 2008

Micrometer‐sized silica spheres with bimodal macromesoporous structures are synthesized continuously by a modified gelation technology, and a novel coaxial microfluidic device is applied to control the size of the silica spheres. These spheres are used as a new protein adsorbent to realize fast adsorption and separation of protein mixture. BSA and lysozyme (LYS) are as model proteins with different sizes and pIs. High protein adsorption capacity and rapid adsorption rate have been achieved. Fast separation of a binary mixture of BSA and LYS through a short packed column (50 mm×4.6 mm id) has also been successfully realized. LYS was selectively adsorbed while BSA flowed through the column in 12 s at a flow rate of up to 5.0 mL/min. As a result, an ultrafast adsorption and separation of BSA and LYS was obtained, showing great potential for applications in fast, large‐scale protein separation processes of these monodispersed silica spheres.
A novel HS‐SBSE system coupled with gas chromatography and mass spectrometry for the analysis of organochlorine pesticides in water samples
Authors: Grossi Paula , Olivares Igor R. B. , de Freitas Diego R. , Lancas Fernando M.
Published: October 2008

A methodology to analyze organochlorine pesticides (OCPs) in water samples has been accomplished by using headspace stir bar sorptive extraction (HS‐SBSE). The bars were in house coated with a thick film of PDMS in order to properly work in the headspace mode. Sampling was done by a novel HS‐SBSE system whereas the analysis was performed by capillary GC coupled mass spectrometric detection (HS‐SBSE‐GC‐MS). The extraction optimization, using different experimental parameters has been established by a standard equilibrium time of 120 min at 85°C. A mixture of ACN/toluene as back extraction solvent promoted a good performance to remove the OCPs sorbed in the bar. Reproducibility between 2.1 and 14.8% and linearity between 0.96 and 1.0 were obtained for pesticides spiked in a linear range between 5 and 17 ng/g in water samples during the bar evaluation.
Influence of galvannealed process on coating corrosion resistance of high strength IF steel
Authors: Xiaodong Hao , Binkai Chen , Wugang Yu , Qifu Zhang
Published: October 2008

Analyzing the influence of different galvannealed process parameters on coating corrosion resistance of high strength IF steel indicated that corrosion resistance rose with the increase in iron content. Corrosion resistance was related to the phase structure of coating and the fraction of different phases. The appearance of compact Γ1phase indicated the great increase in coating corrosion resistance. At the same galvannealed time, coating corrosion resistance became better with the increase in the galvannealed temperature.
X‐Ray photoelectron spectroscopic investigations of powder coated steel
Authors: Hallmeier K. H. , Gehrke J.
Published: October 2008

Polyester powder coatings are used for corrosion protection of different materials. XPS studies were performed in order to characterize such coatings on steel surfaces as a pre‐treatment for following applications like gluing. Different surface treatments by alkaline cleaner, plasma treatment (Plasma Treat® process), and the use of a silicoater (Pyrosil® process) were investigated. In dependence of such treatments, the resulting surfaces are found to be hydrophilic or hydrophobic. Although this behavior can also be investigated by contact‐angle measurements, the aim of our work is the element‐specific characterization of chemical bonding states (speciation).
A comparative study on the corrosion behavior of NdFeB magnets in different electrolyte solutions
Authors: Song Y. W. , Zhang H. , Yang H. X. , Song Z. L.
Published: October 2008

Sintered NdFeB magnets possess excellent magnetic properties. However, the corrosion resistance property of NdFeB is very poor due to its multiphase microstructure consisting of matrix phase Nd2Fe14B, Nd‐rich phase, and B‐rich phase. The corrosion behavior of NdFeB magnets in sodium hydroxide (NaOH), sodium chloride (NaCl), nitric acid (HNO3), and oxalic acid (H2C2O4) solutions was investigated by immersion and electrochemical tests. HNO3is the strongest corrosive electrolyte compared with the other three solutions. The increase in HNO3concentration can accelerate the corrosion of NdFeB magnets. NaCl belongs to medium corrosion electrolyte. A NaCl concentration of 0.5 M shows the severest corrosive feature in comparison with other concentrations of NaCl solution. NdFeB hardly suffers corrosion in NaOH and H2C2O4solutions owing to the formation of passivation films on the surface of magnets. Based on the corrosion behavior of NdFeB in different electrolytes, the possible corrosion mechanisms are discussed.
Interactions of Ionic Liquids with Polysaccharides – 7: Thermal Stability of Cellulose in Ionic Liquids and N‐Methylmorpholine‐N‐oxide
Authors: Dorn Susann , Wendler Frank , Meister Frank , Heinze Thomas
Published: October 2008

The thermal behavior of cellulose dissolved in ionic liquids was studied in comparison to NMMO solutions. The cellulose solutions were characterized by reaction calorimetry and UV‐vis spectroscopy. Generation of chromophoric substances in cellulose/IL solutions is minimized by exposing to temperatures of above 100 °C for longer time periods. Dynamic calorimetric investigations revealed first thermal activities above 180 °C applying EMIMac and above 200 °C for BMIMCl and five other ILs tested. Moreover, even in the case of modified cellulose/IL solutions, e.g., activated charcoal, only a slight decline of onset temperatures was registered compared to modified cellulose/NMMO solutions.

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A convolution for the Hankel–Kontorovich–Lebedev transformation
Authors: Gutiérrez–Tovar Y. E. , Méndez–Pérez J. M. R.
Published: October 2008

The analysis of a kernel involving the product of three Bessel functions motivates the introduction of the translation operator and the convolution associated to the Hankel–Kontorovich–Lebedev tranformation, first in a classical framework, and then in certain spaces of generalized functions. The main properties of this convolution are investigated, the more important operational rules are obtained and some applications are shown. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Carleson measures and conformal self‐mappings in the real unit ball
Authors: Kotilainen Marko , Latvala Visa , Rättyä Jouni
Published: October 2008

Bounded and compact Carleson measures in the unit ball Bof Rn , n ≥ 2, are characterized by means of global Dirichlet integrals of the conformal self‐map Ta taking a ∈ B to the origin. The same proof applies in the unit ball of Cn . It is also proved that the powers of the Jacobian of Ta satisfy the weak Harnack inequality and even Harnack's inequality with a constant independent of a. As an application of these results it is shown that the two different definitions for Carleson measures in the existing literature are equivalent for a certain range of parameter values. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Relating transplantation and multipliers for Dunkl and Hankel transforms
Authors: Nowak Adam , Stempak Krzysztof
Published: October 2008

By expressing the Dunkl transform of order α of a function f in terms of the Hankel transforms of orders α and α + 1 of even and odd parts of f, respectively, we show that a considerable part of harmonic analysis of the Dunkl transform on the real line may be reduced to known results for the Hankel transform. In particular, defining the modified Dunkl transform and then considering the Dunkl transplantation operator we transfer known multiplier results for the Hankel transform to the Dunkl transform setting. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An equivalence for weighted integrals of an analytic function and ist derivative
Authors: Pavlović Miroslav , Peláez José Ángel
Published: October 2008

In this paper we introduce the class of differentiable weights ω in the unit disc 𝔻 such that

equation image

where L is a positive constant.

The main result in this paper asserts that if ω is one of these weights, then the equivalence

equation image

holds for all 0 < p < ∞, 0 < q ≤ ∞and f an analytic function in 𝔻. Our results improve others due to Aleman, Siskakis, and Stević.

We also prove two results on harmonic conjugate functions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonoscillation criteria for second‐order nonlinear differential equations with decaying coefficients
Authors: Sugie Jitsuro
Published: October 2008

This paper is concerned with the problem of deciding conditions on the coefficient q (t) and the nonlinear term g (x) which ensure that all nontrivial solutions of the equation (|x ′|α–1x ′)′ + q (t)g (x) = 0, α > 0, are nonoscillatory. The nonlinear term g (x) is not imposed no assumption except for the continuity and the sign condition xg (x) > 0 if x ≠ 0. In our problem, it is important to examine the relation between the decay of q (t) and the growth of g (x). Our main result extends some nonoscillation theorem for the generalised Emden–Fowler equation. Proof is given by means of some Liapunov functions and phase‐plane analysis. A simple example is includes to show that the monotonicity of g (x) is not essential in our problem. Finally, elliptic equations with the m ‐Laplacian operator are discussed as an application to our results. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Interval oscillation criteria for linear Hamiltonian systems
Authors: Zheng Zhaowen
Published: October 2008

In this paper some new oscillation criteria of interval type for linear matrix Hamiltonian systems are established which are different from most known ones in the sense that they are based on the information only on a sequence of subinterval of [t0, ∞) rather than on the whole half line. Our results are shaper than previous results. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
One‐sided operators inLp(x)spaces
Authors: Edmunds David E. , Kokilashvili Vakhtang , Meskhi Alexander
Published: October 2008

Boundedness of one‐sided maximal functions, singular integrals and potentials is established inL(I) spaces, whereIis an interval inR. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Novel Route to Organic–Inorganic Hybrid Nanomaterials
Authors: Radhakrishnan Bindushree , Constable Andrew N. , Brittain William J.
Published: October 2008

The in situ formation of functionalized silica nanoparticles is reported. The reactive stabilizers used in the study, [3‐(2‐bromoisobutyryl)propyl]triethoxysilane and [3‐(2‐bromoisobutyryl)propyl]ethoxydimethylsilane, have an atom transfer radical polymerization (ATRP) initiator at the noncondensable end. Condensation with tetraethoxysilane yields silica nanoparticles with a surface‐immobilized initiator. The size of these functionalized silica nanoparticles can be controlled by varying the time of initiator addition and initiator concentration. The silica particle sizes ranged from 10 to 300 nm. With the initiator functionalized silica nanoparticles, ATRP synthesis was performed with styrene, tert‐butyl acrylate, and methyl acrylate to produce organic–inorganic nanomaterials.

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Synthesis of Spirobifluorene‐alt‐Carbazole Copolymers with Oxadiazole Pendants and their Thermal, Electrochemical, and Photoluminescent Properties
Authors: Zhang Kai , Zou Yang , Xu Xichen , Gong Shaolong , Yang Chuluo , Qin Jingui
Published: October 2008

Two new carbazole derivatives with the oxadiazole moiety substituted at the 9 position of carbazole have been facilely synthesized by an aromatic nucleophilic substitution reaction of arylamine and fluoroarenes. Alternating copolymers with spirobifluorene were then prepared by a Suzuki coupling reaction. Spirobifluorene units together with the bulky oxadiazole pendant significantly enhance the morphological stability of the copolymers. An increased π‐electron delocalization in P2 with 2,7‐coupling of carbazole results in a decrease of absorption and phosphorescence emission energies as compared to P1 with 3,6‐coupling of the carbazole. The bandgaps and energy levels of the polymers can be tuned by different coupling positions between carbazole and the spirobifluorene moieties.

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Minimizing SONET Add‐Drop Multiplexers in optical UPSR networks using the minimum number of wavelengths
Authors: Wang Yong , Gu Qian‐Ping
Published: October 2008

In SONET/WDM optical networks, a high‐speed wavelength channel is usually shared by multiplexed low‐rate network traffic demands. The multiplexing is known as traffic grooming and carried out by SONET Add‐Drop Multiplexers (SADM). The maximum number of low‐rate traffic demands that can be multiplexed into one wavelength is called the grooming factor. Because SADMs are expensive network devices, a key optimization problem in optical network design is to groom a given set of low‐rate traffic demands such that the number of required SADMs is minimized. This optimization problem is challenging and NP‐hard even for Unidirectional Path‐Switched Ring networks with unitary duplex traffic demands. In this article, we propose two linear‐time approximation algorithms for this NP‐hard problem based on a novel graph partitioning approach. Both algorithms achieve better worst case performance than the previous algorithms. We also show that the upper bounds obtained by our algorithms are very close to the lower bounds for some instances. In addition, both of our algorithms use the minimum number of wavelengths, which are precious resources as well in optical networks. © 2008 Wiley Periodicals, Inc. NETWORKS, 2009
Network design for reverse and closed‐loop supply chains: An annotated bibliography of models and solution approaches
Authors: Akçalı E. , Çetinkaya S. , Üster H.
Published: October 2008

Historically, both the theory and practice of supply chain management have placed an emphasis on manufacturing and distribution operations, i.e., the forward channel, which consists of suppliers, manufacturers, distributors, retailers, and customers. Recently, increased attention to product recovery practices has extended the scope of traditional supply chain management by drawing attention to collection, demanufacturing, and remanufacturing operations, i.e., the reverse channel, which consists of final‐users, collectors, demanufacturers, and remanufacturers. To optimize the performance of the extended supply chain, there is a need to establish an effective and efficient infrastructure via optimal network design. As a result, network design for product recovery has attracted the attention of a growing number of researchers in the past decade. In an attempt to draw more academic attention to this area, this annotated bibliography provides a detailed account of the published literature. The article is organized into two main sections that focus on (i) reverse supply chain network design, which is concerned with establishing an infrastructure to manage the reverse channel only and (ii) closed‐loop supply chain network design, which is concerned with establishing an infrastructure to manage both forward and reverse channels in a coordinated manner. Specifically, we describe the operational characteristics of the underlying supply chain system considered in each paper, highlight the features of the network design model proposed therein, and discuss the proposed solution approach along with a brief description of significant computational work, if available. In conclusion, a critical review of the published literature is given and potential areas for future research are identified. © 2008 Wiley Periodicals, Inc. NETWORKS, 2009
Joint vehicle assembly‐routing problems: An integrated modeling and optimization approach
Authors: Sherali Hanif D. , Ghoniem Ahmed
Published: October 2008

This article examines logistical systems where it is desirable to appropriately ascertain the joint composition of the sequences of vehicles that are to be physically connected along with determining their delivery routes. Such assembly‐routing problems occur in the truck manufacturing industry, for example, where combinations of trucks to be delivered to dealerships are composed and are subsequently dispatched via appropriately optimized delivery routes, which are in turn restricted by the particular sequence in which the trucks are connected. A similar structure is exhibited in the business of shipping goods via boat‐towed barges along inland waterways, or via trains through railroad networks. We present a novel unifying model and a column generation‐based optimization approach for this challenging class of joint vehicle assembly‐routing problems. In addition, we suggest several extensions to accommodate particular industrial settings where assembly sequence‐dependent delivery routes are necessary, as well as those where driver‐ and equipment‐based restrictions are imposed. Computational experience is provided using realistic data from a case‐study involving a major truck manufacturing company to demonstrate the applicability of the proposed methodology in practice. © 2008 Wiley Periodicals, Inc. NETWORKS, 2009
New largest known graphs of diameter 6
Authors: Pineda‐Villavicencio Guillermo , Gómez José , Miller Mirka , Pérez‐Rosés Hebert
Published: October 2008

In the pursuit of obtaining largest graphs of given maximum degree Δ and diameter D, many construction techniques have been developed. Compounding of graphs is one such technique. In this article, by means of the compounding of complete graphs into a bipartite Moore graph of diameter 6, we obtain a family of large graphs of the same diameter. For maximum degrees Δ = 5, 6, 9, 12, and 14, members of this family constitute the largest known graphs of diameter 6. © 2008 Wiley Periodicals, Inc. NETWORKS, 2009
A linear algorithm for finding the k‐broadcast center of a tree
Authors: Harutyunyan Hovhannes A. , Liestman Arthur L. , Shao Bin
Published: October 2008

The term k‐broadcast indicates the process of disseminating a message from one vertex to all vertices of a graph in such a way that in each time unit, an informed vertex can send the message to up to k of its neighbors. The k‐broadcast center of a graph is the set of vertices that can initiate a minimum time k‐broadcast within the graph. We present a linear algorithm to determine the k‐broadcast center of a given tree. From this, we obtain a linear time algorithm for finding the k‐broadcast time of any vertex of the tree and, thus, the k‐broadcast time of the tree itself. © 2008 Wiley Periodicals, Inc. NETWORKS, 2009
Decomposition algorithms for the design of a nonsimultaneous capacitated evacuation tree network
Authors: Andreas April K. , Smith J. Cole
Published: October 2008

In this article, we examine the design of an evacuation tree, in which evacuation is subject to capacity restrictions on arcs. The cost of evacuating people in the network is determined by the sum of penalties incurred on arcs on which they travel, where penalties are determined according to a nondecreasing function of time. Given a discrete set of disaster scenarios affecting network population, arc capacities, transit times, and penalty functions, we seek to establish an optimal a priori evacuation tree that minimizes the expected evacuation penalty. The solution strategy is based on Benders decomposition, in which the master problem is a mixed‐integer program and each subproblem is a time‐expanded network flow problem. We provide efficient methods for obtaining primal and dual subproblem solutions, and analyze techniques for improving the strength of the master problem formulation, thus reducing the number of master problem solutions required for the algorithm's convergence. We provide computational results to compare the efficiency of our methods on a set of randomly generated test instances. © 2008 Wiley Periodicals, Inc. NETWORKS, 2009
Correlation between nanohole volume and mechanical properties of amine‐cured epoxy resin blended with poly(ethylene oxide)
Authors: Ramos J. A. , Larrañaga M. , Mondragon I. , Salgueiro W. , Somoza A. , Goyanes S. , Rubiolo G. H.
Published: October 2008

A set of diglycidylether of bisphenol‐A (DGEBA)/4,4′‐diaminodiphenylmethane (DDM) epoxy matrix modified with poly(ethylene oxide) (PEO), pre‐cured at two different temperatures, was examined by positron annihilation lifetime spectroscopy (PALS). The aim was to investigate the correlation between local free volume and mechanical properties. A negative deviation from the linear additivity rule of the local free volume is observed at both cure schedules. Using together the local free volume and mechanical results allows to conclude that the cure temperature makes small contribution to the flexural strength and modulus of blends but is responsible for the composition‐dependent rise of the fracture toughness. It is proposed that this behavior is a consequence of the nearest‐neighbor intrachain contacts or self‐association of the epoxy‐OH groups during cure leading to a non‐uniform space distribution of the DGEBA–PEO contacts, which causes the deflection of the crack path. Copyright © 2008 John Wiley & Sons, Ltd.
Novel preparation of glass fiber reinforced polytetrafluoroethylene composites for application as structural materials
Authors: Gu Aijuan , Liang Guozheng , Yuan Li
Published: October 2008

A novel method was developed to fabricate continuous glass fiber reinforced polytetrafluoroethylene (PTFE/GF) composites which includes the use of conventional sintering and vacuum assisted resin transfer molding (VARTM), successively. The RTM resin (coded as M4506‐1) “fills” the porosity and defects of original PTFE/GF composites prepared by traditional sintering processing, improves the overall interface bonding between the matrix and fibers, and thus significantly improves the mechanical properties such as the flexural and interlaminar shear strength of fiber reinforced PTFE composites. The present work suggests a new way to produce fiber (especially continuous fiber) reinforced PTFE composites with high mechanical properties, and thus make it potentially possible to use PTFE‐based composites as structural materials. Copyright © 2008 John Wiley & Sons, Ltd.
Synthesis and modification of epoxy resins using recycled poly(ethylene terephthalate)
Authors: Czub Piotr
Published: October 2008

Development of a method of degradation of poly(ethylene terephthalate) (PET) wastes for the preparation of materials for the synthesis and modification of epoxy resins, development of a method of preparation of epoxy resins, characterization of epoxy resins so prepared, and optimization of the composition of epoxy resins modified with recycled materials were the goals of this work. Therefore, the conditions required for the strong degradation of waste PET by glycolysis reaction were chosen. Glycols with different length of alkyl chain were tested. Composition and structure of the degradation products were determined by GPC and spectroscopic methods (i.e. FT‐IR, 1H‐NMR, and 13C‐NMR). Next, the products of waste PET glycolysis were used as polyhydroxylic reagents for the synthesis of epoxy resins by their reaction with epichlorohydrin. Bis(2‐hydroxyalkyl)‐terephthalate was used as a model compound. The products were applied in the preparation of compositions with Bisphenol A‐based low‐molecular‐weight epoxy resins. It was found that modification of epoxy resins with the products of PET degradation led to the improvement of their tensile and flexural strengths, hardness, and thermal stability. Better results were obtained for the products with longer alkyl fragments. The incorporation of alkylether chains from PET glycolysis not only increased water absorption of the modified resins, but also improved their chemical stability against 10% HNO3, 75% H2SO4, and ethyl acetate. Copyright © 2008 John Wiley & Sons, Ltd.
New N‐allylated monomers in the synthesis of practical valuable high‐molecular‐weight compounds
Authors: Gorbunova M. , Vorob'eva A. , Tolstikov A. , Monakov Y.
Published: October 2008

Methods for the synthesis of N‐allylated monomers of new structural types based on transformations of hydrazides of carboxylic acids and guanidine have been developed. A reactivity of N,N‐diallyl‐N′‐acylhydrazines (DAH) and 2,2‐diallyl‐1,1,3,3‐tetraethylguanidiniumchloride (AGC) in reactions of free‐radical homo‐ and copolymerization with sulfur dioxide and vinyl monomers has been studied. The structure of the polymers obtained was identified by NMR 13C. Investigations carried out showed DAH and AGC to copolymerize with vinyl monomers and sulphur dioxide, both double bonds participating with the formation of cis‐, trans‐stereoisomeric pyrrolidine structures in cyclolinear polymer chain. Kinetic regularities of the process and some properties of the copolymers have been investigated. Copyright © 2008 John Wiley & Sons, Ltd.
A novel poly(N‐isopropylacrylamide‐co‐N‐hydroxymethyl acrylamide) gel: preparation in the absence/presence of a pore‐forming agent and characterization
Authors: Gürdağ Gülten , Öz Gökay Mutlu
Published: October 2008

Poly(N‐isopropylacrylamide) (PNIPAM) homopolymer gel and copolymer gels of N‐isopropylacrylamide (NIPAM) and N‐hydroxymethyl acrylamide (NHMAAM) were prepared in the absence/presence of a pore‐forming agents, poly(ethylene glycol) (PEG) (PEG 400 or PEG 2000) using N,N′‐methylenebisacrylamide (NMBA) as a crosslinker in aqueous solution at 4°C. The chemical structures and microscopic morphologies of PNIPAM and P(NIPAM‐co‐NHMAAM) copolymer gels were investigated by FT‐IR and SEM (scanning electron microscopy), respectively. The effects of initial monomer concentration (0.5 and 1 M), the contents of crosslinker (0.25 and 1%) and comonomer (1–3 mol%), the absence/presence of pore‐forming agent in the feed, and the molecular weight of pore‐forming agent on the compressive elastic moduli and equilibrium swelling values (ESVs) of both polymers were investigated. While the use of a pore‐forming agent during the polymer synthesis favored the formation of porous gels and increased the swelling values, it led to decrease in the compressive elastic moduli of PNIPAM and P(NIPAM‐co‐NHMAAM) gels. The swelling values of gels, which were prepared at high monomer (1 M) and crosslinker (1%) contents, were not dependent on the comonomer NHMAAM incorporation to PNIPAM, the use of pore‐forming agents, and the use of former and latter parameters together. The twice increase in initial monomer concentration at low NMBA (0.25%) content highly enhanced the elastic moduli of PNIPAM. One mol% NHMAAM incorporation into PNIPAM especially at low monomer (0.5 M) and crosslinker (0.25%) contents made the highest increase (4.7 times) in the elastic moduli of gel, and further increase in the NHMAAM content of gel decreased the moduli of gels at all crosslinker and monomer concentrations. It was concluded that the increase in the elastic moduli of copolymer gels with 1 mol% NHMAAM, which were prepared at low crosslinker and monomer concentrations, can be attributed to the increase in crosslinking through the condensation reaction between N‐methylol groups or N‐methylol and NH groups in NHMAAM and NIPAM. Copyright © 2008 John Wiley & Sons, Ltd.
Using a polyelectrolyte to fabricate porous polyimide nanoparticles with crater‐like pores
Authors: Zhao Gufan , Ishizaka Takayuki , Kasai Hitoshi , Hasegawa Masatoshi , Nakanishi Hachiro , Oikawa Hidetoshi
Published: October 2008

We have used the reprecipitation method and subsequent two‐step imidization to fabricate highly porous polyimide (PI) nanoparticles possessing crater‐like surface pores (depths, diameters: tens of nanometers) from poly(amic acid) (PAA) derivatives in the presence of poly(sodium‐4‐styrenesulfonate) (PSS) as a polyelectrolytic porogen. The porous structures arose presumably through segregative microphase separation of PAA and PSS (i.e. repulsion between PAA and PSS in the presence of a common solvent) and subsequent removal of PSS. The addition of this strong polyelectrolyte improved the degree of porosity of the resulting PI nanoparticles and allowed controllable release of the porogen. The resulting porous PI nanoparticles exhibited a high thermal stability (5% weight loss at temperature 450°C). This technique is suitable for the preparation of novel low‐k materials and their surface‐related applications. Copyright © 2008 John Wiley & Sons, Ltd.
Investigation of drug release and 1H‐NMR analysis of the in situ forming systems based on poly(lactide‐co‐glycolide)
Authors: Mohamadnia Z. , Ahmadi E. , Rafienia M. , Mirzadeh H. , Mobedi H.
Published: October 2008

In situ forming biodegradable polymeric systems loaded with betamethasone (BTM) and betamethasone acetate (BTMA) were prepared using poly(DL‐lactide‐co‐glycolide) (PLGA), ethyl heptanoate (EH), and N‐methyl‐2‐pyrrolidone (NMP) as the biodegradable polymer, additive, and solvent, respectively. The drug release studies were carried out in buffer (pH = 7.4, 37°C) using high performance liquid chromatography (HPLC). 1H‐NMR was used to determine the polymer degradation behavior, release mechanism, and interactions between the polymer and drug. The 1H‐NMR spectra showed that all interactions between the polymer and drug were hydrogen bonding. Hydroxyl groups and fluorine in drugs were involved in hydrogen bonding with PLGA polymer. In 1H‐NMR studies, we found that the degradation rate in the systems loaded with BTMA was higher than the systems loaded with BTM because BTMA is only slightly soluble and accelerates the hydrolysis of PLGA chains. The formulations loaded with BTM had obviously lower burst release compared with BTMA loaded samples. With respect to 1H‐NMR spectra, the mechanism of BTM release is controlled by two effective factors: solvent removal and polymer degradation. Copyright © 2008 John Wiley & Sons, Ltd.
Alteration of S‐nitrosothiol homeostasis and targets for protein S‐nitrosation in human hepatocytes
Authors: López‐Sánchez Laura M. , Corrales Fernando J. , González Raúl , Ferrín Gustavo , Muñoz‐Castañeda Juan R. , Ranchal Isidora , Hidalgo Ana B. , Briceño Javier , López‐Cillero Pedro , Gómez Miguel A. , De La Mata Manuel , Muntané Jordi , Rodríguez‐Ariza Antonio
Published: October 2008

The liver is one organ clearly influenced by nitric oxide (NO), and acute and chronic exposure to this substance has been associated with distinct patterns of liver disease. Disruption or deregulation of S‐nitrosothiol (SNO) signalling leads to impairment of cellular function and disease, and this study was aimed to identify potential targets for protein S‐nitrosation during alteration of SNO homeostasis in human hepatocytes. Cells were treated with S‐nitroso‐L‐cysteine (CSNO), an effective physiological nitrosothiol for delivering NO bioactivity to cells. Treatment with CSNO augmented the levels of S‐nitrosoproteins detected both by chemiluminescence and the biotin switch method. CSNO treatment also increased S‐nitrosoglutathione reductase (GSNOR) activity that returned SNO content to basal levels. This increased enzymatic activity was related to augmented levels of ADH‐5 mRNA, the gene encoding for GSNOR in humans. In addition, the treatment with the SNO also increased cell death. Twenty S‐nitrosoproteins were identified in CSNO‐treated hepatocytes, including mitochondrial aldehyde dehydrogenase, protein disulphide isomerase, Hsp60, GRP75 and Raf kinase inhibitor protein. The identification in the S‐nitrosatable proteome of proteins involved in metabolism, maintenance of cellular homeostasis and signalling points to the relevance of protein S‐nitrosation to the physiology and pathophysiology of human hepatocytes.
Interaction proteomics of the HMGA chromatin architectural factors
Authors: Sgarra Riccardo , Furlan Cristina , Zammitti Salvina , Lo Sardo Alessandra , Maurizio Elisa , Di Bernardo Julie , Giancotti Vincenzo , Manfioletti Guidalberto
Published: October 2008

The high mobility group A (HMGA) chromatin architectural transcription factors are a group of proteins involved in development and neoplastic transformation. They take part in an articulated interaction network, both with DNA and other nuclear proteins, organizing multimolecular complexes at chromatin level. Here, we report the development of a novel in vitro strategy for the identification of HMGA molecular partners based on the combination of an RP‐HPLC prefractionation procedure, 2‐DE gels, blot‐overlay and MS. To demonstrate that our approach could be a reliable screening method we confirmed a representative number of interactions in vitro by GST pull‐down and far‐Western and in vivo by co‐affinity purification. This approach allowed us to enlarge the HMGA molecular network confirming their involvement also in non‐transcriptional‐related processes such as RNA processing and DNA repair.
Protein Standard Absolute Quantification (PSAQ) for improved investigation of staphylococcal food poisoning outbreaks
Authors: Dupuis Alain , Hennekinne Jacques‐Antoine , Garin Jérôme , Brun Virginie
Published: October 2008

Staphylococcal enterotoxins are major causing agents of food‐borne diseases. Their detection in food remnants for risk assessment or food poisoning outbreaks investigation suffers from a lack in comprehensive immunological tools. In this study, we demonstrate that the combination of immunocapture and Protein Standard Absolute Quantification (PSAQ) strategy, which uses isotope‐labeled enterotoxins as internal standards for MS‐based analysis, is powerful to specifically identify and quantify these contaminating agents in food matrices. This approach is believed to significantly improve the elucidation of staphylococcal food poisoning outbreaks.
Photocatalytic TiO2 – assisted decomposition of Triton X‐100: inhibition of p‐nitrophenol degradation
Authors: Pardo Gloria , Vargas Ronald , Núñez Oswaldo
Published: October 2008

A decrease in the apparent pseudo first‐order rate constant is observed in the photocatalyzed (TiO2) degradation of surfactant Triton X‐100 (Triton) when its concentration is increased. The measured rate versus the concentration profile is consistent with a hyperbolic form (rate increases with concentration) as described by the Langmuir–Hinshelwood (L‐H) model. The rate is then given by the expression: r = kK[Triton]/(1 + K[Triton]) but the apparent rate constant by kapp = kK/(1 + K[Triton]o), where k = 0.66 mg L−1 min−1 and K = 0.037 L mg−1. Therefore, at low [Triton]o, kapp = kK but at high [Triton]o, kapp = k/[Triton]o, that is, an inverse function of the reactant concentration. Although, in the latter case the reaction does not follow first‐order kinetics, its pseudo first‐order deviation is not easily noticeable. Therefore, this decrease in kapp with reactant concentration may limit its use when rate constants are compared to evaluate degradation efficiency or when it is used to show reaction inhibition. However, we have detected p‐nitrophenol inhibition induced by Triton using kapp values. Inhibition is observed at [Triton]o < CMC (critical micelle concentration) and also at [Triton]o > CMC. These inhibitions are consistent with the LH model given by the expression: r = k′K′[phenol]/(1 + K′[phenol]o + K[Triton]o), where [phenol] is equal during all kinetic runs. Copyright © 2008 John Wiley & Sons, Ltd.
Mitochondrial DNA mutation stimulates prostate cancer growth in bone stromal environment
Authors: Arnold Rebecca S. , Sun Carrie Q. , Richards Jendai C. , Grigoriev Galina , Coleman Ilsa M. , Nelson Peter S. , Hsieh Chia‐Ling , Lee Jae K. , Xu Zhiheng , Rogatko Andre , Osunkoya Adeboye O. , Zayzafoon Majd , Chung Leland , Petros John A.
Published: October 2008

BACKGROUND AND OBJECTIVES

Mitochondrial DNA (mtDNA) mutations, inherited and somatically acquired, are common in clinical prostate cancer. We have developed model systems designed to study specific mtDNA mutations in controlled experiments. Because prostate cancer frequently metastasizes to bone we tested the hypothesis that mtDNA mutations enhance prostate cancer growth and survival in the bone microenvironment.

METHODS

The pathogenic nucleotide position (np) 8993 mDNA mutation was introduced into PC3 prostate cancer cells by cybrid formation. Wild‐type and mutant cybrids were grown as nude mouse subcutaneous xenografts with or without bone stromal cell co‐inoculation. Cybrids were also grown in the intratibial space. Tumor growth was assayed by direct tumor measurement and luciferase chemiluminescence. Gene expression was assayed using cDNA microarrays confirmed by real time PCR, western blot analysis and immunohistochemistry.

RESULTS

Cybrids with the 8,993 mtDNA mutation grew faster than wild‐type cybrids. Further growth acceleration was demonstrated in the bone microenvironment. A 37 gene molecular signature characterized the growth advantage conferred by the mtDNA mutation and bone microenvironment. Two genes of known importance in clinical prostate cancer, FGF1 and FAK, were found to be substantially upregulated only when both mtDNA mutation and bone stromal cell were present.

CONCLUSIONS

The ATP6 np 8,993 mtDNA mutation confers a growth advantage to human prostate cancer that is most fully manifest in the bone microenvironment. The identification of specific molecular alterations associated with mtDNA mutation and growth in bone may allow new understanding of prostate cancer bone metastasis. Prostate 69: 1–11, 2009. © 2008 Wiley–Liss, Inc.
Transition zone and anterior stromal prostate cancers: Zone of origin and intraprostatic patterns of spread at histopathology
Authors: Bouyé Sébastien , Potiron Eric , Puech Philippe , Leroy Xavier , Lemaitre Laurent , Villers Arnauld
Published: October 2008

BACKGROUND

To describe the precise location of transition zone (TZ) and anterior fibromuscular stroma (AFMS) prostate cancers (TZ/AFMS) within histological zones at various stages of development and to demonstrate their pattern of intraprostatic spread from their site of origin.

METHODS

Anterior TZ/AFMS cancers excluding the anterolateral part of peripheral zone, were identified from radical prostatectomy specimens. Morphometric histopathological study included largest surface area, volume and spatial distribution.

RESULTS

Out of 91 TZ/AFMS cancers, 79 were <4 cm3 and 69 <2 cm3. Fifty percent and 70% of cancers <4 cm3 were located in the anterior third and inferior half of TZ and/or AFMS, respectively. Cancers <2 cm3 could be classified into three types according to their location related to histologic zone boundaries: TZ type 1 (40%) for cancers confined to one TZ lobe; TZ type 2 (35%) for cancers most represented in one TZ lobe but crossing its anterior boundary; type AFMS (25%) for cancers confined to AFMS. These results form the rationale for the hypothesis that AFMS cancers originate from anterior and medial TZ and due to benign prostatic hypertrophy they become excluded from TZ, anteriorly into AFMS. TZ anterior limit would then act as a barrier to their posterior extension.

CONCLUSIONS

TZ/AFMS cancers contours and locations are predictable and conform to histological zones boundaries. Knowledge of these cancer origin and pattern of spread in TZ and AFMS are of importance for imaging diagnosis, guidance for biopsy and focal therapy. Prostate 69: 105–113, 2009. © 2008 Wiley–Liss, Inc.
Poisson ratio under compressive and tensile strain; effect on the mechanical response of the Cu46Zr54 metallic glass
Authors: Tayebi L. , Lekka Ch. E. , Evangelakis G. A.
Published: October 2008

We present Molecular Dynamics (MD) results demonstrating the effect of the Poisson ratio (PR) changes, occurring upon compressive and tensile deformation, on the mechanical response of Cu46Zr54 metallic glass (MG). We found that the PR value increases under strain, the effect being more pronounced after yielding. These changes are related to microstructural modifications occurring at subnano scale and to the plasticity of the material. In addition, we found that the effect depends on the imposed strain rate, yielding lower plastic region and fracture strain at high deformation rates. These findings indicate that microstructure, intrinsic properties and mechanical response of MGs are closely related and can be used for the design of MGs exhibiting enhanced plasticity. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Detection of CO and NO using low power metal oxide sensors
Authors: Triantafyllopoulou R. , Tsamis C.
Published: October 2008

In this work we present the fabrication and characterization of low power SnO2 gas sensors based on Porous Silicon micro‐hotplates for the detection of toxic gases, like CO and NO. The response of the SnO2 gas sensors was measured for various gas concentrations (100‐500 ppm). Analysis was performed in isothermal operation mode, by keeping constant the micro‐hotplate temperature and in pulsed temperature mode, by applying voltage pulses to the heater. In both cases, the response of the sensors increased as the temperature and the concentration of the detecting gases increased. Comparison between the two different operation modes, shows that the sensors exhibit higher sensitivity in pulsed temperature mode. In addition, with this technique, a significant reduction of power consumption can be achieved. Moreover, the sensors show significant selectivity in detecting NO, so discrimination between the two gases can be achieved. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)