bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

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

AbstractIn 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

AbstractHistorically, 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

AbstractThis 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

AbstractIn 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

AbstractThe 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

AbstractIn 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

AbstractA 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

AbstractA 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

AbstractDevelopment 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

AbstractMethods 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

AbstractPoly(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

AbstractWe 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

AbstractIn 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

AbstractThe 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

AbstractThe 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

AbstractStaphylococcal 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

AbstractA 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.