bluuebunny/crossref_metadata_2025 huggingface dataset:
Construcionismo, práticas discursivas e possibilidades de pesquisa em psicologia social
Authors: Méllo Ricardo Pimentel , Silva Alyne Alvarez , Lima Maria Lúcia Chaves , Di Paolo Angela Flexa
Published: March 2008

Este artigo apresenta o movimento construcionista como uma perspectiva crítica em Psicologia Social que propõe compreender os processos de institucionalização que tornaram certos acontecimentos essencializados. Para tanto, enfoca o estudo das práticas discursivas, considerando a linguagem como prática que provoca efeitos. Essa perspectiva possibilita estudos que focalizam acontecimentos na interface entre os usos da linguagem e as condições de sua produção e veiculação. O movimento indica que é necessário direcionar pesquisas para os regimes de verdade que as práticas discursivas sustentam ou rompem e, também, para as relações de poder que controlam, selecionam e organizam os enunciados.
Comportamento ingestivo diurno de novilhas Jersey sob suplementação com farelo de milho em pastagem de azevém anual
Authors: Moreno Claiton Baes , Fischer Vivian , Monks Pedro Lima , Gomes Jorge Fainé , Stumpf Junior Waldyr
Published: March 2008

O objetivo neste trabalho foi observar o comportamento ingestivo diurno de novilhas Jersey em pastejo, submetidas a suplementação com farelo de milho. Foram utilizadas seis novilhas da raça Jersey, com 6 a 9 meses de idade e peso médio de 105,65 ± 18,2 kg, mantidas em uma pastagem de azevém anual (Lolium multiflorum Lam.), em pastejo contínuo, com lotação variável. Como suplemento, foi fornecido, diariamente às 14 h, farelo de milho na quantidade de 1% do peso vivo. Os animais foram distribuídos aleatoriamente em um delineamento completamente casualizado em parcelas subdivididas, composto de dois tratamentos (com e sem suplementação de farelo de milho), cada um com três animais, durante quatro períodos experimentais. A avaliação do comportamento ingestivo foi realizada visualmente, registrando-se os tempos gastos pastando, ruminando e descansando entre 7 h e 18h30. Os animais que não receberam suplemento apresentaram maior tempo de pastejo, porém menor tempo de descanso e menos períodos de pastejo e descanso que os animais sob suplementação. A suplementação influenciou o comportamento ingestivo diurno de novilhas Jersey.
Resistência ao tratamento nos transtornos de ansiedade: fobia social, transtorno de ansiedade generalizada e transtorno do pânico
Authors: Menezes Gabriela Bezerra de , Fontenelle Leonardo F , Mululo Sara , Versiani Márcio
Published: March 2008

OBJETIVOS: Os transtornos de ansiedade são condições psiquiátricas prevalentes que determinam importante prejuízo funcional, piora na qualidade de vida do indivíduo e um enorme custo social. Embora diversas medicações eficazes para os transtornos de ansiedade encontrem-se disponíveis, um número significativo de pacientes não responde adequadamente ao tratamento e muitos permanecem com sintomas residuais clinicamente significativos. O objetivo deste estudo é rever aspectos relacionados à resistência ao tratamento e estratégias farmacológicas no manejo dos transtornos de ansiedade resistentes ao tratamento. MÉTODO: Revisão narrativa. RESULTADOS: São discutidos os diversos aspectos conceituais relacionados à resistência ao tratamento, os possíveis preditores de resistência e, finalmente, algumas estratégias a serem utilizadas no manejo dos transtornos de ansiedade (incluindo transtorno de ansiedade social, transtorno de ansiedade generalizada e transtorno do pânico) que não respondem às abordagens terapêuticas convencionais. CONCLUSÃO: A resistência ao tratamento ainda é um desafio para a prática clínica que começa em conceitos não operacionalizados de resposta e resistência e termina na escassez de estudos controlados sobre estratégias de tratamento nesse último cenário clínico.
Qualidade informacional e conservadorismo nos resultados contábeis publicados no Brasil
Authors: Coelho Antonio Carlos , Lima Iran Siqueira
Published: March 2008

O artigo avalia a presença de conservadorismo nos resultados apresentados nas demonstrações contábeis publicadas no Brasil pelas sociedades por ação no período de 1995 a 2004. Realiza-se a pesquisa em virtude da constatação de que a regulamentação brasileira, de um lado, é enfática no estabelecimento de princípio ou convenção do conservadorismo - antecipar o registro de perdas e diferir o reconhecimento de receitas - e, de outro, permite o reconhecimento prematuro de receitas não realizadas, como é o caso da reavaliação de ativos. O trabalho testou a antecipação oportuna assimétrica de perdas econômicas através do modelo de Componentes Transitórios nos Lucros (BASU, 1997) e o conservadorismo condicional através do modelo de Associação entre Apropriações Contábeis e Fluxos de Caixa (BALL; SHIVAKUMAR, 2005). A amostra considera sociedades por ações com dados para a série temporal completa, regredindo-se os dados em painel segundo os métodos mais adequados. Os resultados confirmam a hipótese de que os gestores das empresas em questão não praticam o conservadorismo condicional, embora se constate reversão dos componentes transitórios do lucro em maior magnitude no caso de variações negativas do lucro antecedente.
Analysis of Skins and the Performance of Gravel-Packed Completions in Oil and Gas Wells
Authors: Okoye C. U. , Suriyakriangkai S. , Ghalambor A. , Alcocer C.
Published: March 2008

This paper presents solutions and analysis of mathematical model of skins due to completions in gravel packed oil and gas wells. The models can be divided into three cases: (1) Open Hole gravel packed well (2) Cased-hole perforated gravel packed well (3) Collapsed perforation tunnel gravel packed well. The skins due to completion include damaged skin, restricted entry skin, liner skin, gravel packed sand skin, slanted well skin, perforation geometry skin, crushed zone skin, non-darcy skin and the skin in the perforation tunnel.

The results obtained from the calculation in open hole gravel packed show that the skin in damaged zone decreases as the damaged zone permeability increases. For the cased-hole perforated gravel packed oil and gas well, the results show that increasing the perforation radius, perforation length and crushed zone permeability result in the decrease of crushed zone skin for both darcy and non-darcy flow, the perforation geometry skin and skin in the perforation tunnel for both darcy, and non-darcy flow for a given shot density. For the collapsed perforation tunnel gravel packed oil and gas well, the results show that the increasing perforation radius results in the decrease of hemispherical flow geometry skin and skin in the perforation tunnel for both darcy and non-darcy flow for a given shot density.

The solutions of each gravel packed skin model is used to analyze field and experimental data in order to estimate the skins and the decrease or Increase in productivity ratio due to completions in gravel packed wells.
LLECMOD: A Bivariate Population Balance Simulation Tool for Liquid- Liquid Extraction Columns
Authors: Attarakih Menwer M. , Bart Hans-Jörg , Steinmetz Tilmann , Dietzen Markus , Faqir Naim M.
Published: March 2008

The population balance equation finds many applications in modelling poly-dispersed systems arising in many
engineering applications such as aerosols dynamics, crystallization, precipitation, granulation, liquid-liquid, gas-liquid,
combustion processes and microbial systems. The population balance lays down a modern approach for modelling the
complex discrete behaviour of such systems. Due to the industrial importance of liquid-liquid extraction columns for the
separation of many chemicals that are not amenable for separation by distillation, a Windows based program called
LLECMOD is developed. Due to the multivariate nature of the population of droplets in liquid –liquid extraction columns
(with respect to size and solute concentration), a spatially distributed population balance equation is developed. The basis
of LLECMOD depends on modern numerical algorithms that couples the computational fluid dynamics and population
balances. To avoid the solution of the momentum balance equations (for the continuous and discrete phases), experimental
correlations are used for the estimation of the turbulent energy dissipation and the slip velocities of the moving droplets
along with interaction frequencies of breakage and coalescence. The design of LLECMOD is flexible in such a way that
allows the user to define droplet terminal velocity, energy dissipation, axial dispersion, breakage and coalescence frequencies
and the other internal geometrical details of the column. The user input dialog makes the LLECMOD a user-friendly
program that enables the user to select the simulation parameters and functions easily. The program is reinforced by a parameter
estimation package for the droplet coalescence models. The scale-up and simulation of agitated extraction columns
based on the populations balanced model leads to the main application of the simulation tool.
Flag algebras
Authors: Razborov Alexander A.
Published: March 2008

Asymptotic extremal combinatorics deals with questions that in the language of model theory can be re-stated as follows. For finite models M, N of an universal theory without constants and function symbols (like graphs, digraphs or hypergraphs), let p(M, N) be the probability that a randomly chosen sub-model of N with ∣M∣ elements is isomorphic to M. Which asymptotic relations exist between the quantities p(M1,N),…, p(Mh,N), where M1,…, M1, are fixed “template” models and ∣N∣ grows to infinity?

In this paper we develop a formal calculus that captures many standard arguments in the area, both previously known and apparently new. We give the first application of this formalism by presenting a new simple proof of a result by Fisher about the minimal possible density of triangles in a graph with given edge density.
A Longitudinal Assessment of Teacher Education Students' Confidence toward Using Technology
Authors: Milman Natalie B. , Molebash Philip E.
Published: March 2008

This article describes the findings of a longitudinal study examining how teachers' confidence toward using technology have evolved, if at all, since taking an educational technology course during their preservice teacher education experience. Pre- and post-surveys were administered to undergraduate and graduate teacher education students at the beginning and end of an educational technology course, as well as several years later. Findings show that the overall instructional and personal confidence scores were significantly higher than when compared to the pre-course survey mean, although lower than the post-course survey mean.
Exploring the Role of Expectancies in the Mental and Physical Health Outcomes of Written Self-Disclosure
Authors: Patterson Candace L. , Singer Jefferson A.
Published: March 2008

Emotional self-disclosure yields mental and physical health benefits. Methods for enhancing this intervention have largely been ignored in the literature. Building from research that indicates that expectations play a role in self-disclosure's outcomes, the current research examined expectations and self-disclosure. Health outcomes were assessed in 40 female college students who participated in a written self-disclosure exercise for 15 minutes for 3 consecutive days. In order to determine the interactive influence of self-disclosure and expectancy on mental and physical health outcomes, participants self-disclosed a traumatic or trivial topic and the researchers attempted to manipulate participants' expectancies concerning the benefits produced by self-disclosure. Women who disclosed traumas and were given the expectancy that disclosure would yield benefits had decreased interpersonal sensitivity and interpersonal alienation 1 month after disclosure. Limitations and recommendations are discussed. Creating positive expectations may represent a method for enhancing the positive effects of emotional expression.
Personality Correlates of Flying Dreams
Authors: Schredl Michael
Published: March 2008

Despite the fact that flying unaided is not possible in waking life, flying dreams have been reported fairly often. Over the centuries, a large number of scientists have speculated about the etiology of such dreams. Their occurrence in a student sample ( N = 444) was related to low neuroticism, openness to experience, boundary thinness, dream recall frequency and playing an instrument. The findings of the present study indicate that psychological factors play a role in the explanation of flying dreams. This does not completely rule out any of the physiological theories. The traits associated with flying dreams positively support the continuity hypothesis at the level of emotions. Future studies should measure the current frequency of flying dreams and correlate this variable with the dreamer's current emotional state in waking life.
The Dialectical Phenomena and Processes of the Mind
Authors: Vyner Henry M.
Published: March 2008

For the last 14 years, the author has been interviewing Tibetan lamas at considerable length about their experiences of their own mind in meditation for the purposes of: 1) developing a formal descriptive science of the phenomena that appear in the stream of consciousness; and 2) using that descriptive science to describe the defining characteristics of the healthy human mind. This paper will present the central elements of the descriptive science of the stream of consciousness that has been generated by these interviews. It will do so as a means of making the case that the psychological processes that appear in the stream of consciousness have, as a group, a coherent functional identity. This paper will also present representative excerpts from the interviews from which the descriptive science has been derived.
Abnormal Muscle Spindle Innervation and Large-Fiber Neuropathy in Diabetic Mice
Authors: Muller Karra A. , Ryals Janelle M. , Feldman Eva L. , Wright Douglas E.
Published: March 2008

OBJECTIVE—Large-fiber diabetic polyneuropathy (DPN) leads to balance and gait abnormalities, placing patients at risk for falls. Large sensory axons innervating muscle spindles provide feedback for balance and gait and, when damaged, can cause altered sensorimotor function. This study aimed to determine whether symptoms of large-fiber DPN in type 1 and type 2 diabetic mouse models are related to alterations in muscle spindle innervation. In addition, diabetic mice were treated with insulin to assess whether sensorimotor and spindle deficits were reversible.

RESEARCH DESIGN AND METHODS—Behavioral assessments were performed in untreated and treated streptozotocin (STZ)-injected C57BL/6 mice to quantitate diabetes-induced deficits in balance and gait. Quantification of Ia axon innervation of spindles was carried out using immunohistochemistry and confocal microscopy on STZ-injected C57BL/6 and db/db mice.

RESULTS—STZ-injected C57BL/6 mice displayed significant and progressive sensorimotor dysfunction. Analysis of Ia innervation patterns of diabetic C57BL/6 spindles revealed a range of abnormalities suggestive of Ia axon degeneration and/or regeneration. The multiple abnormal Ia fiber morphologies resulted in substantial variability in axonal width and inter-rotational distance (IRD). Likewise, db/db mice displayed significant variability in their IRDs compared with db+ mice, suggesting that damage to Ia axons occurs in both type 1 and type 2 diabetes models. Insulin treatment improved behavioral deficits and restored Ia fiber innervation in comparison with nondiabetic mice.

CONCLUSIONS—Similar to small fibers, Ia axons are vulnerable to diabetes, and their damage may contribute to balance and gait deficits. In addition, these studies provide a novel method to assay therapeutic interventions designed for diabetes-induced large-fiber dysfunction.
Physico-chemical and Biological Aspects of Monsoon Waters of AShulia for Economic and Aesthetic Applications: Preliminary Studies
Authors: Khan Md. Ariful Islam , Hossain AMM Maruf , Huda ME , Islam M Shahidul , Elahi Syed Fazle
Published: March 2008

In the north-eastern part of Dhaka the 'Turag River' extends over Ashulia thana with a few branches. The north-eastern part of Ashulia thana mainly constitute low lands with a physiography of Madhupur Tract interlaced with Brahmaputra Floodplain. Monsoon extends over these lands from May to October and from July to October these lands remain flooded with a water depth of more than 180 cm to less than 275 cm due to surface runoff of rain water and overflow of the river canals. The area under water during this four month period can be used for economic applications such as various types of fishery as well as enhancing the present recreational applications. For these purposes the physical, chemical, and biological aspects of the water are studied to evaluate its suitability for the applications. The study was held over the period of July through December, 2006, samples being taken once every month. The physical parameters covered transparency, odor, temperature, salinity, EC, TSS, and TDS. The chemical parameters of water studied were pH, DO, BOD5, COD, hardness, NO2---N, NO3---N, PO43---P, SO42---S, Cl-, Na, K, Ca, Fe, Ni, Cu, Zn, Cd, Pb, and Hg. Among the biological parameters 'phytoplankton' and 'zooplankton' were qualitatively identified in microscopic observation up to genera. From July to October the water was transparent and of good odor, temperature ranged from 28.2°C to 24.6°C, salinity within 0.58 to 0.83 mg/L, EC within 250 to 608 ? mho/cm, TSS 0.42 to 0.82 mg/L, and TDS within 2.8 to 5.2 mg/L. Among the chemical parameters, pH ranged from 6.6 to 7.4, DO within 6.4 to 6.9 mg/L, BOD5 within 1.5 to 3.28 mg/L, COD within 3.04 to 12.89 mg/L, hardness 26.08 to 37.5 mg/L, NO2--N from undetectable to maximum 0.562 mg/L, NO3--N within 0.539 to 2.158 mg/L, PO43--P 2.35 to 2.75 mg/L, SO42--S 0.23 to 0.29 mg/L, Cl- 1.65 to 6.16 mg/L, Na 3.6 to 12.5 mg/L, K 9.7 to 11.5 mg/L, Ca 6.52 to 14.82 mg/L, Fe 0.1269 to 0.5062 mg/L, Ni 0.028 to 0.050 ?g/L, Cu 0.028 to 0.043 mg/L, Zn 0.023 to 0.048 ?g/L, Cd 0.0023 to 0.0043 ?g/L, Pb 0.043 to 0.093 ?g/L, and Hg was not detected at ppb level. Among the biological parameters a number of phytoplankton were identified covering the classes of Bacillariophyceae, Chlorophyceae, Euglenophyceae, and Cyanophyceae. The zooplanktons included the orders Cladocera and Copepoda within the class Crustacea of phylum Arthropoda.

Key words: Freshwater ecology, Water resource management

Bangladesh J. Sci. Ind. Res. 42(4), 377-396, 2007
Propagation of Heavy Metals in Poultry Feed Production in Bangladesh
Authors: Islam M Shahidul , Kazi M Azizul Islam , Hossain M Moazzem , Ahsan M Aminul , Hossain AMM Maruf
Published: March 2008

Poultry is one of the major protein sources for people in Bangladesh. It is a promising sector. It requires large scale feed production activities. There are various sources of raw materials for poultry feed production. In many ways these sources can be associated with anthropogenic heavy metal pollution. It is better to monitor any probable propagation of heavy metals into the food chain through the final feeds rather than the various raw materials for feeds. Three widely used feeds - Usha, Fresh, and Saudi-Bangla feeds were selected for the study. Cadmium, lead, arsenic, mercury, selenium, chromium, manganese, nickel, copper, and zinc contents of all samples were measured. The detected maximum and minimum concentrations of these elements were found to be: 0.1852 ppm and 0.0232 ppm for cadmium, 20.6498 ppm and 0.6019 ppm for lead, 0.7640 ppm and 0.0069 ppm for arsenic, 0.0579 ppm and 0.0116 ppm for mercury, 0.0347 ppm and 0.0069 ppm for selenium, 5.7875 ppm and 0.0926 ppm for chromium, 302.2001 ppm and 0.0695 ppm for manganese, 5.1625 ppm and 0.0125 ppm for nickel, 37.5725 ppm and 0.0463 ppm for copper, and 422.3023 ppm and 0.0232 ppm for zinc. The "Poultry Feed Reference Standards, February 2002", prepared by Ministry of Fisheries and Livestock, Govt. of the People's Republic of Bangladesh contains no standards for the heavy metals as contaminants into poultry feeds which demands immediate attention.

Key words: Heavy metal, Poultry feed, Environmental health.

Bangladesh J. Sci. Ind. Res. 42(4), 465-474., 2007
Alkylation of Xylenes with Cyclohexene in the Presence of p-Toluenesulphonic Acid
Authors: Saha Manoranjan , Dey Haradhan Chandra , Karim Mohammad Ziaul , Ismail Mohammad , Saha Dipti
Published: March 2008

Isomeric xylenes have been cycloalkylated with cyclohexene in the presence of p-toluenesulphonic acid as catalyst. The effects of the variation of temperature, molar ratio of xylene to cyclohexene, time of reaction and amount of p-toluenesulphonic acid on the reactions have been studied and cyclohexyl xylenes have been obtained in high yield.
Evolutionary perspective on indirect victimization in adolescence: the role of attractiveness, dating and sexual behavior
Authors: Leenaars Lindsey S. , Dane Andrew V. , Marini Zopito A.
Published: March 2008

We studied indirect victimization from an evolutionary perspective by examining links between this type of victimization and several indicators of attractiveness (past sexual behavior, dating frequency and physical appearance). Two thousand three hundred and nineteen (56% female) students (ages 13–18) from a region of southern Ontario, Canada, completed self‐report measures of indirect victimization, physical appearance, dating frequency, recent sexual behavior (number of partners in previous month) and past sexual behavior (number of lifetime partners minus number of partners in previous month) as well as indexes of depression, aggression and attachment security, which were used to control for psychosocial maladjustment. Consistent with an evolutionary framework, physical appearance interacted significantly with gender, wherein attractive females were at greater risk for indirect victimization, whereas for males physical attractiveness was a protective factor, reducing risk of victimization. Physical appearance also interacted with grade, being inversely related to indirect victimization for younger adolescents and having a nonsignificant association with victimization for older youth. Finally, recent sexual behavior was associated with increased risk of indirect victimization for older adolescents only, which we discussed with regard to peer perceptions of promiscuity and short‐term mating strategies. These findings have important implications for the development of interventions designed to reduce peer victimization, in that victims of indirect aggression may represent a rather broad, heterogeneous group, including attractive individuals with no obvious signs of maladjustment. Aggr. Behav. 34:404–415, 2008. © 2008 Wiley‐Liss, Inc.
Holt–Oram syndrome associated with anomalies of the feet
Authors: Garavelli L. , De Brasi D. , Verri R. , Guareschi E. , Cariola F. , Melis D. , Calcagno G. , Salvatore F. , Unger S. , Sebastio G. , Albertini G. , Rivieri F. , Soli F. , Superti‐Furga A. , Gentile M.
Published: March 2008

Holt–Oram syndrome (HOS) (OMIM 142900) is characterized by upper‐extremity malformations involving the radial, thenar, or carpal bones and a personal and/or family history of congenital heart defects (CHDs). It is inherited in an autosomal dominant manner. The TBX5 gene located on chromosome 12 (12q24.1) is the only gene currently known to be associated with HOS and is associated with variable phenotypes. We report on the clinical and molecular characterization of a HOS family with three affected individuals and a novel mutation (Lys88ter). We discuss genotype–phenotype correlations, the presence of foot anomalies in one affected individual, and the role of atypical features in HOS differential diagnosis. © 2008 Wiley‐Liss, Inc.
DRD3, but not COMT or DRD2, genotype affects executive functions in healthy and first‐episode psychosis adolescents
Authors: Bombin Igor , Arango Celso , Mayoral María , Castro‐Fornieles Josefina , Gonzalez‐Pinto Ana , Gonzalez‐Gomez Cristina , Moreno Dolores , Parellada Mara , Baeza Inmaculada , Graell Montserrat , Otero Soraya , Saiz Pilar A. , Patiño‐Garcia Ana
Published: March 2008

Catechol‐O‐methyltransferase (COMT) and dopamine receptors 2 (DRD2) and 3 (DRD3) have been associated with a higher risk of developing psychosis and with dopaminergic system (DAS) regulation. Frontal cognitive functioning has been proven to be a useful endophenotype for psychosis and it is partially controlled by the DAS. Val158Met (rs4680, COMT), Taq IA (rs1800497, DRD2) and Ser9Gly (rs6280; DRD3) polymorphisms were analyzed in a sample of 84 adolescent Caucasian patients with first‐episode psychosis (ages 11–17) and 85 healthy Caucasian controls (ages 10–17). A comprehensive neuropsychological battery, assessing attention, working memory, memory, and executive functions, was administered to the entire sample. The relationship between neuropsychological scores and genotype was determined. Subjects with the DRD3 Gly/Gly genotype showed significantly poorer performance than Ser/Ser subjects in executive functioning tasks (P = 0.002; adjusted R2 = 0.031), with no significant differences in the other cognitive paradigms. Neither COMT nor DRD2 polymorphisms significantly contributed to variance in cognition in our adolescent sample. The DRD3 Ser9Gly polymorphism seems to be involved with prefrontal cognition. This effect seems to be heterogeneous in terms of cognitive paradigms. The lack of association between COMT and DRD2 genotypes and cognition in our sample may be partially explained by the young age of the sample and the clinical heterogeneity of the patients. © 2008 Wiley‐Liss, Inc.
Dominance relationships among one‐male units in a provisioned free‐ranging band of the Sichuan snub‐nosed monkeys (Rhinopithecus roxellana) in the Qinling Mountains, China
Authors: Zhang Peng , Watanabe Kunio , Li Baoguo , Qi Xiaoguang
Published: March 2008

We studied the dominance relationships among one‐male units (OMUs) in a provisioned free‐ranging band of the Sichuan snub‐nosed monkeys (Rhinopithecus roxellana) in the Qinling Mountains of central China from 2001 to 2005. The band was composed of 6–8 OMUs that stayed in the band for several years. Linear dominance orders could be detected using displacement interactions with directional asymmetry among OMUs in 82.3±5% of interactions, and ambiguous and reversed interactions in 17.7±5%. The dominance rank of OMUs was positively related with the duration of their stay in the band, and this may be attributed to the association of the resident male with adult females, rather than the fighting ability of resident males, as males do not fight seriously with each other. Subordinate units were observed to merge with dominant units resulting in an elevation of their rank order. The linear dominance relationship among OMUs in the Sichuan snub‐nosed monkeys may have evolved as a result of competition for preferred food trees. Am. J. Primatol. 70:634–641, 2008. © 2008 Wiley‐Liss, Inc.
Chitosan conjugated with deoxycholic acid and gallic acid: A novel biopolymer‐based additive antioxidant for polyethylene
Authors: Pasanphan Wanvimol , Buettner Garry R. , Chirachanchai Suwabun
Published: March 2008

Chitosan, as a novel bioadditive antioxidant for commodity polymer, is proposed. Chitosan is successfully conjugated with deoxycholic acid and gallic acid (chitosan‐DC‐GA) via a simple reaction using the 1‐ethyl‐3‐(3′‐dimethylaminopropyl) carbodiimide/N‐hydroxysuccinimide conjugating agent at room temperature in a heterogeneous system. Chitosan‐DC‐GA shows a deoxycholic acid (DC) and gallic acid (GA) content of about 40% each. Chitosan‐DC‐GA exhibits DPPH radical scavenging ability with EC50 1 mg mL−1 based on the EPR technique evaluation. A model case study of chitosan‐DC‐GA with low‐density polyethylene (LDPE) confirms improvement in compatibility, as seen from the sheet clarity, as well as the good dispersion of chitosan‐DC‐GA in LDPE matrices, as observed by scanning electron microscope. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Synthesis and properties of starch‐graft‐acrylic acid/Na‐montmorillonite superabsorbent nanocomposite hydrogels
Authors: Al Ebru , Güçlü Gamze , İyim Tülin Banu , Emik Serkan , Özgümüş Saadet
Published: March 2008

The graft copolymerization of acrylic acid (AA) onto starch was carried out with monomer/starch weight ratio = 1.5. Cerium ammonium nitrate (CAN) and N,N′‐methylenebis acrylamide (NMBA) were used as initiator and crosslink agent, respectively. Na‐montmorillonite was used as nanoparticles. Starch‐graft‐acrylic acid/Na‐MMT (S‐g‐AA/MMT) nanocomposite hydrogels were characterized by X‐ray diffraction (XRD) and FTIR analysis. The effect of Na‐MMT content in nanocomposite hydrogels on the swelling behavior was investigated. Increasing the Na‐MMT/monomers ratio up to 1% causes an increment in water absorbency, which indicates that Na‐MMT can improve the ability of water absorbency but further increase of Na‐MMT causes a decrease in water absorbency. In addition, we describe the removal of safranine T from aqueous solutions using S‐g‐AA/MMT nanocomposite hydrogels. Effects of various parameters such as treatment time, initial dye concentration, and amount of the Na‐MMT were investigated. The Freundlich equations were used to fit the equilibrium isotherms. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Effect of high temperature alkali cooking on the constituents, structure and thermal degradation of hemp fiber
Authors: Feng Xin‐xing , Chen Jian‐yong , Zhang Hua‐peng
Published: March 2008

Degumming of hemp fiber by high temperature alkali cooking was investigated, and the effect of temperature and dosage of alkali on the constituents, structure, and thermal degradation of hemp fiber was also discussed in this work. The morphology, structure, and thermal degradation of hemp fiber after high temperature cooking were investigated through SEM, FTIR, WAXD, and TG analysis. The results indicated that the high temperature cooking process was effective for removing hemicelluloses and lignin and could also improve the thermal stability of cellulose. Crystallinity index of the treated hemp fiber was increased, which was related to the cooking temperature and NaOH dosage. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Thermal and physicomechanical properties of ethylene‐vinyl acetate copolymer and layered double hydroxide composites
Authors: Ramaraj B. , Yoon Kuk Ro
Published: March 2008

A series of ethylene‐vinyl acetate (EVA) copolymer films have been prepared with different compositions viz. 2, 4, 6, and 8 wt % layered double hydroxide (LDH) nanoparticles by solution intercalation method. These solution‐casted EVA/LDH nanocomposite films were dried and characterized by differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. EVA/LDH films were further tested for tensile strength, density, moisture content, solubility resistance, flammability, and electrical properties. The DSC and FTIR analysis indicate strong interactions between the LDH layers and vinyl acetate groups in EVA. Further, EVA nanocomposite films show enhanced tensile strength, limiting oxygen index (LOI), and flammability rating for the addition of LDH without sacrificing the electrical properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008
Thermophysical and thermomechanical properties of Norland Optical Adhesives and liquid crystal composites
Authors: Benmouna Réda , Benyoucef Boumediène
Published: March 2008

Thermophysical and thermomechanical properties of UV‐cured Norland Optical Adhesives (NOA65) and low molecular weight Liquid Crystal E7 systems were investigated. Thin films of Polymer Dispersed Liquid Crystal were prepared by Polymerization Induced Phase Separation and UV‐curing. Phase diagrams were established using Polarized Optical Microscopy and DSC to determine the lines of nematic to isotropic phase transition as well as the glass transition temperature changes with the system composition. Mechanical measurements were performed in the static and dynamic modes to determine the moduli in terms of the curing time, the temperature and the amount of low molecular weight liquid crystal molecules. Thermomechanical measurements were found to overestimate the glass transition temperature as compared to calorimetric data. Variations of the Young's modulus and the molecular weight defining the mesh size of the network were analyzed in terms of the curing time and liquid crystal concentration. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Properties of styrene‐methyl methacrylate grafted DPNR latex at different monomer concentrations
Authors: Man Siti Hajjar Che , Hashim Azanam S. , Akil Hazizan Md.
Published: March 2008

The graft copolymerization of styrene and methyl methacrylate (MMA) on to deproteinized natural rubber (DPNR) latex was carried out. The effect of monomer concentrations on grafting efficiency, thermal and mechanical properties was studied. The synthesized graft copolymers were characterized by proton nuclear magnetic resonance (1H NMR) and the highest grafting efficiency was found at 20 wt % monomer concentration. At low monomer concentration (10 wt %) the grafting was not significant and at 30 wt %, the grafting efficiency was slightly decreased. The thermal properties of graft copolymers were analyzed using differential scanning calorimeter (DSC) and thermal gravimetric analysis (TGA). The degradation temperature (Tdeg) of the graft copolymer was increased with the increase in monomer concentration which indicates the improvement in thermal stability. The DSC result showed improvement in miscibility between the components as the monomer concentration increased. The mechanical properties of gum and filled modified NR were also investigated in terms of tensile strength, tensile modulus and elongation at break. The tensile strength and elongation at break decreased with an increase in monomer concentration while tensile modulus increased as the monomer concentration increased. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Dynamic properties of rubber vibration isolators and antivibration performance of ethylene–propylene–diene monomer/nylon 6 blend systems
Authors: Wu Jyh‐Horng , Li Chia‐Hao , Chiu Hsien‐Tang , Shong Zhi‐Jian
Published: March 2008

This article examines thermoplastic elastomers (TPEs) and thermoplastic vulcanizates (TPVs) as two types of elastomers from melt‐blended and dynamically vulcanized ethylene–propylene–diene monomer (EPDM) rubber materials and nylon 6 plastic materials. A series of investigations were conducted on the mechanical properties, morphology, dynamic mechanical properties, hysteresis behavior, and dynamic antivibration properties with different nylon 6 contents. The experimental results showed that the incompatibility between EPDM and nylon 6 led to the easy destruction of the TPV materials in two interfacial polymers upon the application of an external force. Thus, after a dynamic vulcanization process, the mechanical properties of the EPDM/nylon 6 blends were not as good as those of the TPE materials. In terms of morphology, nylon 6 plastics were uniformly distributed in the EPDM/nylon 6 blends during the EPDM rubber phase before vulcanization was performed. After the dynamic vulcanization, phase inversion was produced in which rubber microparticles were formed and dispersed in the nylon 6 plastic phase. The results of dynamic mechanical analysis, compression vibration hysteresis behavior, and dynamic property antivibration experiments showed that the blends provided better vibration isolation and antivibration performance after the amount of nylon 6 was increased and EPDM and nylon 6 were blended through dynamic vulcanization. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008
Proteome‐based identification of fusion partner for high‐level extracellular production of recombinant proteins in Escherichia coli
Authors: Qian Zhi‐Gang , Xia Xiao‐Xia , Choi Jong Hyun , Lee Sang Yup
Published: March 2008

Extracellular production of recombinant proteins in Escherichia coli has several advantages over cytoplasmic or periplasmic production. However, nonpathogenic laboratory strains of E. coli generally excrete only trace amounts of proteins into the culture medium under normal growth conditions. Here we report a systematic proteome‐based approach for developing a system for high‐level extracellular production of recombinant proteins in E. coli. First, we analyzed the extracellular proteome of an E. coli B strain, BL21(DE3), to identify naturally excreted proteins, assuming that these proteins may serve as potential fusion partners for the production of recombinant proteins in the medium. Next, overexpression and excretion studies were performed for the 20 selected fusion partners with molecular weights below 40 kDa. Twelve of them were found to allow fused proteins to excrete into the medium at considerable levels. The most efficient excreting fusion partner, OsmY, was used as a carrier protein to excrete heterologous proteins into the medium. E. coli alkaline phosphatase, Bacillus subtilis α‐amylase, and human leptin used as model proteins could all be excreted into the medium at concentrations ranging from 5 to 64 mg/L during the flask cultivation. When only the signal peptide or the mature part of OsmY was used as a fusion partner, no such excretion was observed; this confirmed that these proteins were truly excreted rather than released by outer membrane leakage. The recombinant protein of interest could be recovered by cleaving off the fusion partner by enterokinase as demonstrated for alkaline phosphatase as an example. High cell density cultivation allowed production of these proteins to the levels of 250–700 mg/L in the culture medium, suggesting the good potential of this approach for the excretory production of recombinant proteins. Biotechnol. Bioeng. 2008;101: 587–601. © 2008 Wiley Periodicals, Inc.
Effect of surface roughness of Ti, Zr, and TiZr on apatite precipitation from simulated body fluid
Authors: Chen Xiaobo , Nouri Alireza , Li Yuncang , Lin Jianguo , Hodgson Peter D. , Wen Cui'e
Published: March 2008

Some of the critical properties for a successful orthopedic or dental implant material are its biocompatibility and bioactivity. Pure titanium (Ti) and zirconium (Zr) are widely accepted as biocompatible metals, due to their non‐toxicity. While the bioactivity of Ti and some Ti alloys has been extensively investigated, there is still insufficient data for Zr and titanium–zirconium (TiZr) alloys. In the present study, the bioactivity, that is, the apatite forming ability on the alkali and heat treated surfaces of Ti, Zr, and TiZr alloy in simulated body fluid (SBF), was studied. In particular, the effect of the surface roughness characteristics on the bioactivity was evaluated for the first time. The results indicate that the pretreated Ti, Zr and TiZr alloy could form apatite coating on their surfaces. It should be noted that the surface roughness also critically affected the bioactivity of these pretreated metallic samples. A surface morphology with an average roughness of approximately 0.6 µm led to the fastest apatite formation on the metal surfaces. This apatite layer on the metal surface is expected to bond to the surrounding bones directly after implantation. Biotechnol. Bioeng. 2008;101: 378–387. © 2008 Wiley Periodicals, Inc.
Directed evolution of LuxI for enhanced OHHL production
Authors: Kambam Pavan Kumar Reddy , Sayut Daniel J. , Niu Yan , Eriksen Dawn T. , Sun Lianhong
Published: March 2008

Quorum sensing is a common mechanism used by bacteria to coordinate population behavior, and is involved in a variety of biological processes, such as bioluminescence, virulence factor synthesis, antibiotic production, and biofilm formation. To engineer the LuxI enzyme of the LuxI–LuxR quorum‐sensing system, we developed a high throughput genetic selection to identify LuxI mutants with improved OHHL (3‐oxo‐hexanoyl homoserine lactone) synthesis in E. coli. Using this genetic selection, we created LuxI mutants with improved OHHL synthesis rates and yields through directed evolution, identifying three LuxI mutants after two generations. An in vivo semi‐quantitative method allowed for verification of the genetic screen and OHHL yields were quantified using HPLC–MS/MS, revealing an 80‐fold increase in a mutant culture compared to the wildtype culture. In addition to OHHL, the yields of C6HSL (hexanoyl homoserine lactone) and C8HSL (octanoyl homoserine lactone) were also improved, and a slight change in substrate specificity towards C6HSL production was observed. Based on alignment with the crystal structure of EsaI, a homolog of LuxI, two mutations are most likely involved in enhancing the interactions between the enzyme and the substrates. The high throughput genetic selection and the semi‐quantitative method can be conveniently modified for the directed evolution of LuxI homologs. The identification of these LuxI mutants has implications in synthetic biology, where they can be used for the construction of artificial genetic circuits. In addition, development of drugs that specifically target quorum sensing to attenuate the pathogenesis of gram‐negative infectious bacteria might also benefit from the insights into the molecular mechanism of quorum sensing revealed by the amino acid substitutions. Biotechnol. Bioeng. 2008;101: 263–272. © 2008 Wiley Periodicals, Inc.
Single‐layer perceptron and dynamic neuron implementing linearly non‐separable Boolean functions
Authors: Chen Fangyue , Tang Wenhui , Chen Guanrong
Published: March 2008

This paper presents a single‐layer perceptron (SLP) scheme with an impulse activation function (IAF) and a dynamic neuron (DN) with a trapezoidal activation function (TAF). Combining with some interesting properties of the offset levels, it is shown that many linearly non‐separable Boolean functions can be realized by using only one SLPwIAF or one DNwTAF. In the present work, a few appropriate IAF and TAF are adopted, and the inverse offset level method is used for the design of the SLPwIAF synaptic weights and the DNwTAF templates. The XOR and NXOR Boolean operations with two inputs and all 152 non‐separable Boolean functions with three inputs can be easily implemented by one SLPwIAF or one DNwTAF. Finally, the entire set of 152 DNwTAF templates associated with 152 non‐separable Boolean functions of three inputs is completely listed. Copyright © 2008 John Wiley & Sons, Ltd.
A Nearly Planar Stannene with a Reactive Tin–Carbon Double Bond
Authors: Fatah Abdoul , El Ayoubi Rami , Gornitzka Heinz , Ranaivonjatovo Henri , Escudié Jean
Published: March 2008

Bis(2,4,6‐triisopropylphenyl)‐2,7‐di‐tert‐butylfluorenylidenestannane, Tip2Sn=CR2, an isolable stannene that displays a deep‐purple colour, was synthesized by dehydrofluorination of the corresponding fluorostannane by tert‐butyllithium. It exhibits the shortest Sn=C distance [2.003(5) Å] and the slightest twisting around this unsaturation (10°) among the known stannenes. Its reaction with benzaldehyde according to a [2+2] cycloaddition and that with α‐ethylenic aldehydes and ketones such as crotonaldehyde and methyl vinyl ketone by a [2+4] cycloaddition proceeded in near‐quantitative yield. With acetone, an ene reaction occurred. The four‐membered ring 1,2‐oxastannacyclobutane obtained with benzaldehyde underwent a ring expansion with a second molecule of benzaldehyde to afford the six‐membered ring dioxastannacyclohexane.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Theoretical Study on a Class of Organometallic Complexes Based on All‐Metal Aromatic Ga3– Through Sandwiching Stabilization
Authors: Yang Li‐ming , Li Xiao‐ping , Ding Yi‐hong , Sun Chia‐chung
Published: March 2008

We report the theoretical study on a class of organometallic complexes containing the all‐metal aromatic unit Ga3– on the basis of density functional theory calculations on a series of model sandwich‐like compounds [DM(Ga3)]q– as well as those of the saturated compounds [DMn(Ga3)] [D = Ga3–, Cp–(C5H5–); M = Li, Na, K, Be, Mg, Ca] and extended compounds (Cp–)m(Li+)n(Ga3–)o (m, n, and o are integers). For the six metals, the all‐metal aromatic Ga3– can only be assembled and stabilized in the “heterodecked sandwich” scheme (e.g. [CpM(Ga3)]q–) so as to avoid cluster fusion. Moreover, we designed a novel class of all‐metal aromatic “metalloid” compounds. The ground state heterodecked sandwich species (Cp)–(M)q+(Ga3)– (M = Li, Na, K, q = 1; M = Be, Mg, Ca, q = 2) and the extended sandwich species (Cp–)m(Li+)n(Ga3–)o are mainly ionic bonded, cluster‐assembled “polyatomic molecule”, grown from the combination of Cp–, M atoms, and Ga3–. As a prototype for ionic bonding involving intact Ga3– subunits, [CpM(Ga3)]q– may be a stepping stone toward forming ionic, cluster‐assembled all‐metal aromatic Ga3‐based bulk solids or materials. Additionally, our results for the first time showed that the electronic, structural, and aromatic properties of the all‐metal aromatic Ga3– could be well retained during cluster assembly, which is indicative of “building block” character. Bearing the significant difference in bonding patterns between our designed metalloid compounds and the known metalloid species, synthesis of these novel species might present an attractive challenge to experimental chemists. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
A Carbonyl Group Bridging Four Metal Atoms in a Homoleptic Carbonylmetal Cluster: The Remarkable Case of ­Co4(CO)11
Authors: Zhang Xiuhui , Li Qian‐shu , Xie Yaoming , King R. Bruce , Schaefer Henry F.
Published: March 2008

The unsaturated Co4(CO)11 is predicted by density functional theory (B3LYP and BP86 functionals) to have a structure with one μ4‐CO group bridging all four cobalt atoms in a Co4 butterfly, with five Co–Co bonds in the range 2.44–2.56 Å. This μ4‐CO group is predicted to have a relatively long C–O bond of 1.226 Å (BP86) with a correspondingly low ν(CO) frequency of 1636 cm–1. Co4(CO)11 structures of higher energy have Co4 tetrahedra (6 Co–Co bonds) or Co4 butterflies (5 Co–Co bonds) with a collection of terminal, edge‐bridging, and face‐bridging CO groups forming a total of 15 or 16 Co–C bonds. The predicted molecular structures show no signs of cobalt–cobalt multiple bonding. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Reusable Polymer‐Supported Amine‐Copper Catalyst for the Formation of α‐Alkylidene Cyclic Carbonates in Supercritical Carbon Dioxide
Authors: Jiang Huan‐Feng , Wang A‐Zhong , Liu Hai‐Ling , Qi Chao‐Rong
Published: March 2008

A green, simple and effective polymer‐supported catalytic system has been developed for the cyclization of propargyl alcohols with carbon dioxide (CO2). α‐Alkylidene cyclic carbonates were obtained in satisfactory isolated yields in most cases. The catalyst could be recovered by simple filtration and reused several times without significant loss of activity. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Solvent‐Dependent Regiochemical Cyclotrimerisation of Phenylacetylene with Cobalt Catalysts Containing Disulfide Ligands: A Case Study
Authors: Hilt Gerhard , Hengst Christoph , Hess Wilfried
Published: March 2008

The intermolecular cobalt‐catalysed cyclotrimerisation of phenylacetylene as a benchmark alkyne with [1,2‐bis(4‐methoxyphenylthio)ethane]cobalt dibromide gave the symmetrical 1,3,5‐triphenylbenzene as the major product when dichloromethane was used as the solvent, whereas the unsymmetrical 1,2,4‐trisubstituted product was obtained in acetonitrile in quantitative yield. Optimisation of the aromatic and aliphatic disulfide ligands in different solvents is discussed.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)