bluuebunny/crossref_metadata_2025 huggingface dataset:
A Matter of Timing: Unsynchronized Antigen Expression and Antigen Presentation Diminish Secondary T Cell Responses
Authors: Elnekave Mazal , Bivas-Benita Maytal , Gillard Geoffrey O. , Sircar Piya , Hovav Avi-Hai
Published: June 2009

Despite the low and short expression of secondary Ag, prime-boost immunizations using homologous or heterologous vectors are capable of amplifying memory CD8+ T cells. This is mainly attributed to the rapid presentation of Ag by APCs and the high proliferative capacity of memory CD8+ T cells. Nevertheless, certain viruses and vectors often require prolonged Ag presentation for optimal T cell priming, and the influence of such a prolonged presentation during secondary immune induction is not clear. To address this issue, we primed and boosted mice intradermally (i.d.) with plasmid DNA that was recently reported to require prolonged Ag presentation for maximal CD8+ T cell priming. Although functional memory CD8+ T cells were present in the mice after i.d. priming, the secondary CD8+ T cell response elicited was limited and reached a similar level of that observed during priming. The initial levels of secondary Ag expressed in the boosted mice were sufficient to prime CD8+ T cell response in naive hosts, suggesting that lower Ag load alone does not explain the limited secondary immune responses observed. Removal of the injection site 5 or 10 days after i.d. boosting immunization resulted in diminished Ag presentation and no expansion of memory CD8+ T cells. In fact, Ag-presenting activity following boost occurred mainly two weeks postimmunization, a time when the Ag was no longer expressed in situ. These findings suggest that when the boosting vector triggers prolonged Ag presentation, the lack of synchronicity between Ag accessibility and Ag presentation limits secondary immune responses.
Mycobacterium bovis Bacillus Calmette-Guérin Infection Induces TLR2-Dependent Peroxisome Proliferator-Activated Receptor γ Expression and Activation: Functions in Inflammation, Lipid Metabolism, and Pathogenesis
Authors: Almeida Patrícia E. , Silva Adriana R. , Maya-Monteiro Clarissa M. , Töröcsik Dániel , D′Ávila Heloisa , Dezsö Balázs , Magalhães Kelly G. , Castro-Faria-Neto Hugo C. , Nagy Laszlo , Bozza Patrícia T.
Published: June 2009

Macrophages have important roles in both lipid metabolism and inflammation and are central to immunity to intracellular pathogens. Foam-like, lipid-laden macrophages are present during the course of mycobacterial infection and have recently been implicated in mycobacterial pathogenesis. In this study, we analyzed the molecular mechanisms underlying the formation of macrophage lipid bodies (lipid droplets) during Mycobacterium bovis bacillus Calmette-Guérin (BCG) infection, focusing on the role of the lipid-activated nuclear receptor peroxisome proliferator-activated receptor γ (PPARγ). We found that BCG infection induced increased expression of PPARγ that paralleled the augmented lipid body formation and PGE2 synthesis in mouse peritoneal macrophages. BCG-induced PPARγ expression and lipid body formation were diminished in macrophages from TLR2-deficient mice, suggesting a key role for TLR2. The function of PPARγ in modulating BCG infection was demonstrated by the capacity of the PPARγ agonist BRL49653 to potentiate lipid body formation and PGE2 production; furthermore, pretreatment with the PPARγ antagonist GW9662 inhibited BCG-induced lipid body formation and PGE2 production. BCG-induced MIP-1α, IL12p70, TNF-α, and IL6 production was not inhibited by GW9662 treatment. Nonpathogenic Mycobacterium smegmatis failed to induce PPARγ expression or lipid body formation. Moreover, inhibition of PPARγ by GW9662 enhanced the mycobacterial killing capacity of macrophages. Our findings show that PPARγ is involved in lipid body biogenesis, unravels a cross-talk between the innate immune receptor TLR2 and the lipid-activated nuclear receptor PPARγ that coordinates lipid metabolism and inflammation in BCG-infected macrophages, thereby potentially affecting mycobacterial pathogenesis.
Proteases Induce Production of Thymic Stromal Lymphopoietin by Airway Epithelial Cells through Protease-Activated Receptor-2
Authors: Kouzaki Hideaki , O'Grady Scott M. , Lawrence Christopher B. , Kita Hirohito
Published: June 2009

Thymic stromal lymphopoietin (TSLP) is produced by epithelial cells and triggers dendritic cell-mediated Th2-type inflammation. Although TSLP is up-regulated in epithelium of patients with asthma, the factors that control TSLP production have not been studied extensively. Because mouse models suggest roles for protease(s) in Th2-type immune responses, we hypothesized that proteases from airborne allergens may induce TSLP production in a human airway epithelial cell line, BEAS-2B. TSLP mRNA and protein were induced when BEAS-2B cells were exposed to prototypic proteases, namely, trypsin and papain. TSLP induction by trypsin required intact protease activity and also a protease-sensing G protein-coupled receptor, protease-activated receptor (PAR)-2; TSLP induction by papain was partially dependent on PAR-2. In humans, exposure to ubiquitous airborne fungi, such as Alternaria, is implicated in the development and exacerbation of asthma. When BEAS-2B cells or normal human bronchial epithelial cells were exposed to Alternaria extract, TSLP was potently induced. The TSLP-inducing activity of Alternaria was partially blocked by treating the extract with a cysteine protease inhibitor, E-64, or by infecting BEAS-2B cells with small interfering RNA for PAR-2. Protease-induced TSLP production by BEAS-2B cells was enhanced synergistically by IL-4 and abolished by IFN-γ. These findings demonstrate that TSLP expression is induced in airway epithelial cells by exposure to allergen-derived proteases and that PAR-2 is involved in the process. By promoting TSLP production in the airways, proteases associated with airborne allergens may facilitate the development and/or exacerbation of Th2-type airway inflammation, particularly in allergic individuals.
Pulmonary Inflammation Triggered by Ricin Toxin Requires Macrophages and IL-1 Signaling
Authors: Lindauer Meghan L. , Wong John , Iwakura Yoichiro , Magun Bruce E.
Published: June 2009

Ricin is a potent ribotoxin considered to be a potentially dangerous bioterrorist agent due to its wide availability and the possibility of aerosol delivery to human populations. Studies in rodents and nonhuman primates have demonstrated that ricin delivered to the pulmonary system leads to acute lung injury and symptoms resembling acute respiratory distress syndrome. Increasing evidence suggests that the inflammatory effects triggered by ricin are responsible for its lethality. We demonstrated previously that ricin administered to the lungs of mice causes death of pulmonary macrophages and the release of proinflammatory cytokines, suggesting macrophages may be a primary target of ricin. Here we examined the requirement for macrophages in the development of ricin-mediated pulmonary inflammation by employing transgenic (MAFIA) mice that express an inducible gene driven by the c-fms promoter for Fas-mediated apoptosis of macrophages upon injection of a synthetic dimerizer, AP20187. Administration of aerosolized ricin to macrophage-depleted mice led to reduced inflammatory responses, including recruitment of neutrophils, expression of proinflammatory transcripts, and microvascular permeability. When compared with control mice treated with ricin, macrophage-depleted mice treated with ricin displayed a reduction in pulmonary IL-1β. Employing mice deficient in IL-1, we found that ricin-induced inflammatory responses were suppressed, including neutrophilia. Neutrophilia could be restored by co-administering ricin and exogenous IL-1β to IL-1α/β−/− mice. Furthermore, IL1Ra/anakinra cotreatment inhibited ricin-mediated inflammatory responses, including recruitment of neutrophils, expression of proinflammatory genes, and histopathology. These data suggest a central role for macrophages and IL-1 signaling in the inflammatory process triggered by ricin.
Sickle cell knowledge, premarital screening and marital decisions among local government workers in Ile-Ife, Nigeria
Authors: Abioye-Kuteyi Emmanuel A. , Oyegbade Olanrewaju , Bello Ibrahim , Osakwe Chiddude
Published: June 2009

Background: In Nigeria, as in the rest of equatorial Africa, sickle cell disease (SCD) has its highest incidence and continues to cause high morbidity and early death. The condition is a major public health problem among the black race. The aim of this survey is to determine the level of knowledge about SCD and the factors associated with its prevention among local government workers in Ile- Ife.Method: This is a cross-sectional descriptive study of the knowledge about SCD, attitude towards premarital sickle cell screening and marital decisions among local government workers in Ile-Ife, Nigeria, using a self-administered questionnaire.Results: 69% of study subjects had poor knowledge of SCD, while attitude towards premarital screening was favourable in 95% of the study subjects. Knowledge and attitude were significantly better among subjects with tertiary education. There was a strong positive association between attitude towards sickle cell screening and a history of undergoing screening or partner screening. Most (86.7%) of the respondents and 74.0% of their partners have had sickle cell screening. One-quarter of married and engaged respondents did not know their partner’s sickle cell status. One-third to two-thirds of study subjects will continue the relationship with their partner when either or both have haemoglobinopathy.Conclusion: This study showed poor knowledge of SCD among the studied subjects. There is a need for more emphasis on health education through programmes promoting sickle cell education. In addition, the development of multifaceted patient and public health education programmes, the intensification of screening for the control of SCD by heterozygote detection, particularly during routine preplacement and premarital medical examinations, and the provision of genetic counselling to all SCD patients and carriers are vital to the identification and care of the couples at risk. These will enhance the capacity of the intending couples to make informed decisions and be aware of the consequences of such decisions. Policies are needed to ensure easily accessible community-wide sickle cell screening and premarital and genetic counselling to achieve the desired decline in new births of children with SCD.
Economic activities, illness pattern and utilisation of health care facilities in the rural population of KwaZulu-Natal, South Africa
Authors: Hoque Monjurul
Published: June 2009

Background: The study was undertaken among the rural and black communities of the Uthungulu health district of the KwaZulu-Natal province, South Africa.Method: A cross-sectional community-based descriptive study was conducted. A multi-stage sampling strategy was adopted to obtain a representative sample of the communities.Results: The mean age of the population was 27 years and majority was female (54%). Among the adult population only 30% were educated, 19% were engaged in some form of economic activities while 9% were in the formal employment sector. The average monthly income per household was R1 301 (95% CI, R1 283; R1 308). The illnesses were reported by 27% of the total population over a period of one month. Notably higher rates of female individuals (29%) were sick compared to males (24%, p < 0.001). The rates of illnesses among adult females (39%) were also significantly higher than among males (31%, p < 0.009). Most of them (69%) attended primary health care (PHC) clinics for medical services, while 67% reported chronic conditions. Age (OR = 1.4), gender (OR = 0.711), education (OR = 0.64) and economic activities (OR = 1.9) were found to be associated with being ill or not.Conclusion: The rural black communities are underdeveloped and deprived, which results in higher prevalence of illnesses; however, the utilisation of PHC facilities is comparatively higher than in the rest of the province and other parts of the country. Interventions to improve community health care services among the deprived population should be focused through public health strategies such as all-encompassing PHC that includes health promotion, education and basic essential amenities.
Quality of life of parents of children with newly diagnosed specific learning disability
Authors: Karande S , Kulkarni S
Published: June 2009

Background:

Poor school performance in children causes significant stress to parents.

Aims:

To analyze the quality of life (QOL) of parents having a child with newly diagnosed specific learning disability (SpLD) and to evaluate the impact of clinical and socio-demographic characteristics on their QOL.

Design:

Cross-sectional questionnaire-based study.

Setting:

Learning disability clinic in tertiary care hospital. Materials and Methods: From June 2006 to February 2007, 150 parents (either mother or father) of children consecutively diagnosed as having SpLD were enrolled. Parent's QOL was measured by the WHOQOL-100 instrument which is a generic instrument containing 25 facets of QOL organized in six domains.

Statistical Analysis Used:

Independent samples t-test, one-way analysis of variance, and multiple regression analysis were carried out for statistical significance.

Results:

Mean age of parents was 42.6 years (SD 5.5); mothers to fathers ratio 1.3:1; and 19 (12.7%) were currently ill. Only four WHOQOL-100 domains (psychological > social relationships > environment > spiritual) and five WHOQOL-100 facets (leisur > pfeel > energy > esteem > sex) contributed significantly to their "overall" QOL. Female gender, being currently ill, being in paid work, and having a male child were characteristics that independently predicted a poor domain/facet QOL score. Conclusions: The present study has identified domains and facets that need to be addressed by counselors for improving overall QOL of these parents. Initiating these measures would also improve the home environment and help in the rehabilitation of children with SpLD.
Patient controlled sedation during central neuraxial anesthesia
Authors: Tripathi M , Nath SS , Chaudhary A , Singh PK , Pandey CM
Published: June 2009

Background:

Patient controlled sedation (PCS) gives liberty to patients to choose the time of sedative administration to attain a desired level of comfort.

Aims:

The PCS use was evaluated in patients during surgery under central neuraxial blockade.

Settings and Design:

Prospective, cross-sectional, clinical study on consecutive patients in a tertiary care university hospital. Materials and Methods: PCS technique, using propofol (1%) 2 ml in 2 min was used in 160 adult patients undergoing urologic procedures under central neuraxial block. We observed the time to first PCS activation by patient, duration of surgery, propofol dose, sedation score, hemodynamic stability, patient's acceptability, and the factors correlating with the PCS use.

Statistical analysis used:

Non-parametric two-tailed Pearson's test, univariate correlation analysis for the factors favoring PCS use followed by multivariate logistic regression analysis amongst correlating factors.

Results:

In our cohort, the majority (83%) of the patients activated PCS during surgery under central neuraxial blocks at median time of 30 min and (17%) did not activate PCS. Female patients activated sedation earlier (median 15 min) than male patients (median 30 min). All patients were hemodynamically stable and without significant side effects. Multivariate analysis showed that sedative use significantly (P <0.05) correlated with female gender (odds ratio-3.54 [IR-2.64 to 4.73]) and prolonged surgery (>90 min). Majority (91%) of patients rated PCS technique excellent to good.

Conclusions:

PCS was very well accepted by patients during central neuraxial block. Propofol regimen (2 ml in 2 min) in PCS was safe, as it caused neither apnea nor significant hypotension.
Prevalence and risk factors for female sexual dysfunction in women attending a medical clinic in south India
Authors: Singh JC , Tharyan P , Kekre NS , Singh G , Gopalakrishnan G
Published: June 2009

Background:

Reports from India on the prevalence and determinants of female sexual dysfunction (FSD) are scant.

Aims:

To determine the prevalence and risk factors for FSD.

Settings and Design:

A cross-sectional survey in a medical outpatient clinic of a tertiary care hospital.

Materials and Methods:

We administered a Tamil version of the Female Sexual Function Index (FSFI) to 149 married women. We evaluated putative risk factors for FSD. We elicited participant's attributions for their sexual difficulties.

Statistical Analysis:

We estimated the prevalence of possible FSD and sexual difficulties from published FSFI total and domain cut-off scores. We used logistic regression to identify risk factors for possible FSD. Results: FSFI total scores suggested FSD in two-thirds of the 149 women (73.2%; 95% confidence intervals [CI] 65.5% to 79.6%). FSFI domain scores suggested difficulties with desire in 77.2%; arousal in 91.3%; lubrication in 96.6%; orgasm in 86.6%, satisfaction in 81.2%, and pain in 64.4%. Age above 40 years (odds ratios [OR] 11.7; 95% CI 3.4 to 40.1) and fewer years of education (OR 1.2; 95% CI 1.0 to 1.3) were identified by logistic regression as contributory. Women attributed FSD to physical illness in participant or partner, relationship problems, and cultural taboos but none had sought professional help.

Conclusions:

Sexual problems suggestive of dysfunction, as suggested by FSFI total and domain scores, are highly prevalent in the clinic setting, particularly among women above 40 and those less educated, but confirmation using locally validated cut-off scores of the FSFI is needed.
Renal amyloidosis secondary to childhood tuberculosis
Authors: Krishnamurthy S , Samanta D , Yadav S
Published: June 2009

Childhood renal amyloidosis is a rare entity and is mostly secondary in nature. We describe two cases of renal amyloidosis in association with childhood tuberculosis. The first case was a 10-year-old girl who presented with abdominal tuberculosis and nephrotic syndrome, while the second case was a 5-year-old boy who presented with disseminated tuberculosis and nephrotic syndrome. They were found to have amyloidosis on renal biopsy. The former was treated with anti-tubercular drugs, while the latter required anti-tubercular drugs and steroids. Both the cases showed clinical improvement with remission of nephrotic syndrome. Successful treatment of tuberculosis can result in remission of nephrotic syndrome due to secondary renal amyloidosis. It is important, especially in developing countries, to be aware that tuberculosis continues to be part of the differential diagnosis of amyloidosis in children.
Interface Engineering of Inorganic Thin‐Film Solar Cells – Materials‐Science Challenges for Advanced Physical Concepts
Authors: Jaegermann Wolfram , Klein Andreas , Mayer Thomas
Published: June 2009

The challenges and research needs for the interface engineering of thin‐film solar cells using inorganic‐compound semiconductors are discussed from a materials‐science point of view. It is, in principle, easily possible to define optimized device structures from physical considerations. However, to realize these structures, many materials' limitations must be overcome by complex processing strategies. In this paper, interface properties and growth morphology are discussed using CdTe solar cells as an example. The need for a better fundamental understanding of cause–effect relationships for improving thin‐film solar cells is emphasized.
Control of a high‐purity ethylene glycol reactive distillation column with insights of process dynamics
Authors: Huang Kejin , Zhu Fanghong , Ding Wenming , Wang San‐Jang
Published: June 2009

Inventory control is often regarded as less important than product quality control in the operation of reactive and nonreactive distillation columns (i.e., often detuned considerably in control system design). For the high‐purity ethylene glycol reactive distillation column, the inventory control of top condenser is, however, an exception and plays actually a crucial role in the stable and effective process operation, reminding the necessity to thoroughly investigate the intricate dynamic mechanism and its complicated implications on control system synthesis and design. In this article, the dynamics of a high‐purity ethylene glycol reactive distillation column is examined, and it is found that the complicated dynamics, for example, the nonminimum phase behavior and process nonlinearity, can be suppressed considerably with the tight inventory control of the top condenser. Moreover, an extremely low controllability is detected, implying the potential difficulties in process operation and thus the need of process design modification. In terms of these insights obtained, two control schemes are devised and studied. It is demonstrated that sharp improvement could be acquired in control system performance when the tight inventory control has been implemented in the top condenser. © 2009 American Institute of Chemical Engineers AIChE J, 2009
A bi‐order kinetic model for poly(methyl methacrylate) decomposition in HNO3 using microwave irradiation
Authors: Lin Chun‐Chih , Guo Gia‐Luen , Tsai Tsuey‐Lin
Published: June 2009

In this study, a novel bi‐order model combined with zero‐ and first‐order kinetics was proposed for the decomposition of PMMA (MW = 120,000 g/mol) in concentrated HNO3 by microwave irradiation. To develop and validate this model, Fourier Transform Infrared spectroscopy, scanning electron microscopy, fractional‐life method, the gravimetric analysis and Newton's method were utilized. Rate constants, activation energies, the pre‐exponential factors and the weight fractions (ϕ) via main‐chain scission for the decomposition at 423–453 K were derived from this model. The zero‐order reaction was observed dominant at 423–443 K, while the first‐order reaction dominated at 453 K and 473 K. The digestion efficiency increased as HNO3 was increased to >3 mL at 423 K–443 K. At 473 K, the digestion was almost 100% when HNO3 volume was >3 mL. The estimated ϕ values increased with HNO3 volume at 423 and 443 K, but varied insignificantly at 453 and 473 K. © 2009 American Institute of Chemical Engineers AIChE J, 2009
Experimental and numerical investigation of the precipitation of barium sulfate in a rotating liquid film reactor
Authors: Guo Shengchang , Evans David G. , Li Dianqing , Duan Xue
Published: June 2009

Precipitation of nanosized barium sulfate in a rotating liquid film reactor (RLFR) has been investigated experimentally and through simulations based on the computational fluid dynamics technique including the population balance equation coupled with the Navier–Stokes equations, renormalization group k–ε model equations, and species transport equations. A comparative experiment was carried out involving conventional precipitation in a flask. The structure of the precipitate was identified by powder X‐ray diffraction (PXRD), which showed that the crystals obtained using the RLFR were smaller in size than those obtained in the flask. Transmission electron microscopy (TEM) images demonstrated that the crystals produced by the two different processes had different morphologies. Further detailed experiments involving varying the operating parameters of the RLFR were performed to investigate the effects on crystal size distribution (CSD). Increasing the speed of the rotor in the RLFR in the range 1000–5000 rpm or increasing the rotor‐stator gap in the range 0.1–0.5 mm resulted in a decrease in particle size and narrower particle size distributions. The simulation results suggested that turbulent effects and reaction processes in the effective reactor space were directly related to rotor speed and rotor‐stator gap. The simulated volume weighted mean diameter and CSD of particles of barium sulfate were almost identical to the corresponding experimental results obtained using TEM and laser particle size analyzer. The effects of other parameters such as the Kolmogorov scale and competition between induction time and mixing time are also discussed. © 2009 American Institute of Chemical Engineers AIChE J, 2009
Modeling and simulation of the sequencing batch reactor at a full‐scale municipal wastewater treatment plant
Authors: Ni Bing‐Jie , Xie Wen‐Ming , Liu Shao‐Gen , Yu Han‐Qing , Wang Ying‐Zhe , Gan‐Wang  , Dai Xian‐Liang
Published: June 2009

In this work, we attempted to modify the Activated Sludge Model No.3 and to simulate the performance of a full‐scale sequencing batch reactor (SBR) plant for municipal wastewater treatment. The long‐term dynamic data from the continuous operation of this SBR plant were simulated. The influent wastewater composition was characterized using batch measurements. After incorporating all the relevant processes, the sensitivity of the stoichiometric and kinetic coefficients for the model was thoroughly analyzed prior to the model calibration. The modified model was calibrated and validated with the data from both batch‐ and full‐scale experiments. Model predictions were compared with routine data in terms of chemical oxygen demand, NH4+‐N and mixed liquid volatile suspended solids in the SBR, combined with batch experimental data under different conditions. The model predictions match the experimental results well, demonstrating that the model is appropriate to simulate the performance of a full‐scale wastewater treatment plant even operated under perturbation conditions. © 2009 American Institute of Chemical Engineers AIChE J, 2009
APOE mRNA and protein expression in postmortem brain are modulated by an extended haplotype structure
Authors: Bekris Lynn M. , Galloway Nichole M. , Montine Thomas J. , Schellenberg Gerard D. , Yu Chang‐En
Published: June 2009

Currently the ε4 allele of the apolipoprotein E gene (APOE) is the strongest genetic risk factor for late onset Alzheimer's disease (AD). However, inheritance of the APOE ε4 allele is not necessary or sufficient for the development of AD. Genetic evidence suggests that multiple loci in a 70 kb region surrounding APOE are associated with AD risk. Even though these loci could represent surrogate markers in linkage disequilibrium with APOE ε4 allele, they could also contribute biological effects independent of the APOE ε4 allele. Our previous study identified multiple SNPs upstream from APOE that are associated with cerebrospinal fluid apoE levels, suggesting that a haplotype structure proximal to APOE can influence apoE expression. In this study, we examined apoE expression in human post‐mortem brain (PMB), and constructed chromosome‐phase‐separated haplotypes of the APOE proximal region to evaluate their effect on PMB apoE expression. ApoE protein expression was found to differ among AD brain regions and to differ between AD and control hippocampus. In addition, an extended APOE proximal haplotype structure, spanning from the TOMM40 gene to the APOE promoter, may modulate apoE expression in a brain region‐specific manner and may influence AD disease status. In conclusion, this haplotype–phenotype analysis of apoE expression in PMB suggests that either; (1) the cis‐regulation of APOE expression levels extends far upstream of the APOE promoter or (2) an APOE ε4 allele independent mechanism involving the TOMM40 gene plays a role in the risk of AD. © 2009 Wiley‐Liss, Inc.
Relationship of cranial robusticity to cranial form, geography and climate in Homo sapiens
Authors: Baab Karen L. , Freidline Sarah E. , Wang Steven L. , Hanson Timothy
Published: June 2009

Variation in cranial robusticity among modern human populations is widely acknowledged but not well‐understood. While the use of “robust” cranial traits in hominin systematics and phylogeny suggests that these characters are strongly heritable, this hypothesis has not been tested. Alternatively, cranial robusticity may be a response to differences in diet/mastication or it may be an adaptation to cold, harsh environments. This study quantifies the distribution of cranial robusticity in 14 geographically widespread human populations, and correlates this variation with climatic variables, neutral genetic distances, cranial size, and cranial shape. With the exception of the occipital torus region, all traits were positively correlated with each other, suggesting that they should not be treated as individual characters. While males are more robust than females within each of the populations, among the independent variables (cranial shape, size, climate, and neutral genetic distances), only shape is significantly correlated with inter‐population differences in robusticity. Two‐block partial least‐squares analysis was used to explore the relationship between cranial shape (captured by three‐dimensional landmark data) and robusticity across individuals. Weak support was found for the hypothesis that robusticity was related to mastication as the shape associated with greater robusticity was similar to that described for groups that ate harder‐to‐process diets. Specifically, crania with more prognathic faces, expanded glabellar and occipital regions, and (slightly) longer skulls were more robust than those with rounder vaults and more orthognathic faces. However, groups with more mechanically demanding diets (hunter‐gatherers) were not always more robust than groups practicing some form of agriculture. Am J Phys Anthropol, 2010. © 2009 Wiley‐Liss, Inc.
Effect of polyethyleneoxide and sodium chloride over the micellization behavior of sodium dodecyl sulfate
Authors: Baloch Musa Kaleem , Ahmad Farzana , Rauf Abdur , Durrani Gulrez Fatima
Published: June 2009

Micellization behavior of sodium dodecyl sulfate (SDS) and its mixture with polyethylene oxide (PEO) are investigated using surface tension and light scattering techniques. The data are presented and interpreted in a novel way, which provides more and reliable information about the interaction of the components. The concentration of SDS corresponding to the initiation of interaction with PEO (T1) and the saturation point (T3) are well identified in this way. It has been observed that the concentration span between T1 and T3 is not much affected by the amount of PEO added. The detail investigation of data concludes that SDS and PEO interactions are in one to one ratio at molecular level and CMC decreases with the addition of salt to the system and the micelles become more compact. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Effect of vinyl acetate on aging mechanism of polyacrylate under UV light
Authors: Zhang Weili , Zheng Jing , Huang Guangsu , Li Guangxian
Published: June 2009

Diversity of aging behaviors of polyacrylate and poly(vinyl acetate‐acrylate) with the ultraviolet light radiation was studied. The aging degree was evaluated and the mechanism dominated the behaviors was investigated by color aberration, the degree of cross‐linking, molecular weight and its distribution by gel permeation chromatography (GPC), ultraviolet absorption spectroscopy (UV–vis), and fourier transform infrared spectrometer (FTIR). These studies found that although photodegradation mechanism of poly(vinyl acetate‐acrylate) still preserves three main steps of the scission of main chain, formation of double bond and the generation of cross‐linking reaction, introducing structural units of vinyl acetate to polyacrylate cause the rules various. The structural units can aggravate the aging of polyacrylate, through increasing formation of double bonds and generating cross‐linking reaction. However, what is interesting is that the structural units can strikingly restrain main chain from scission. It is significant for modifying the photodegradation behaviors of polyacrylate coatings. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
End pressure corrections in capillary rheometry of concentrated suspensions
Authors: Wang Z. Y. , Joshi S. C. , Lam Y. C. , Chen X.
Published: June 2009

The end effect of a capillary die was investigated on concentrated suspensions with different particle concentrations, using dies with different diameters and at different temperatures. Nonlinearity in the Bagley plots was observed experimentally, and the nonlinearity increased with increasing particle concentration, decreasing temperature, and smaller capillary dies. Calculated end pressures based on the nonlinear Bagley plots were compared with those measured using an orifice die. As the extruded melts tended to stick on the exit wall of the capillary die, measurements by orifice die registered (40–50%) higher losses than those obtained from Bagley corrections. The key factors, which include particle concentration, contraction ratio, temperature, and flow rate, were discussed for their effects on end pressure. A formula was proposed combining the effects of these factors. Good agreement was obtained between the calculated end pressures with predicted results by the proposed formula. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Characterization of random and multiblock copolymers of highly sulfonated poly(arylene ether sulfone) for a proton‐exchange membrane
Authors: Liang Cui , Maruyama Tatsuo , Ohmukai Yoshikage , Sotani Tomohiro , Matsuyama Hideto
Published: June 2009

Random and multiblock copolymers of sulfonated poly(arylene ether sulfone) (SPAES) were synthesized and characterized to compare the differences in the properties of proton‐exchange membranes made with random and multiblock SPAES copolymers. Atomic force microscopy observations and small‐angle X‐ray scattering measurements suggested the presence of nanoscale, clusterlike structures in the multiblock SPAES copolymers but not in the random SPAES copolymers. Proton‐exchange membranes were prepared from random and multiblock copolymers with various ion‐exchange capacities (IECs). The water uptake, proton conductivity, and methanol permeability of the SPAES membranes depended on the IECs of the random and multiblock SPAES copolymers. At the same IEC, the multiblock SPAES copolymers exhibited higher performances with respect to proton conductivity and proton/methanol permeation selectivity than the random SPAES copolymers. The higher performances of the multiblock SPAES copolymers were thought to be due to their clusterlike structure, which was similar to the ionic cluster of a Nafion membrane. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Effects of the polymerization and pervaporation operating conditions on the dehydration performance of interfacially polymerized thin‐film composite membranes
Authors: Huang Shu‐Hsien , Jiang George J. , Liaw Der‐Jang , Li Chi‐Lan , Hu Chien‐Chieh , Lee Kueir‐Rarn , Lai Juin‐Yih
Published: June 2009

The disadvantage of dense polyamide membranes when applied in the pervaporation separation process is their low permeation rates. To improve the pervaporation performance, polyamide thin‐film composite membranes were prepared via the interfacial polymerization reaction between ethylenediamine (EDA) and trimesoyl chloride (TMC) on the surface of modified polyacrylonitrile (mPAN) membranes. These composite membranes were applied in the pervaporation separation of alcohol aqueous solutions. On the basis of the best pervaporation performance, the desired polymerization conditions for preparing the polyamide thin‐film composite membranes (EDA–TMC/mPAN) were as follows: (1) the respective concentration and contact time of the EDA aqueous solution were 5 wt % and 30 min and (2) the respective concentration of and immersion time in the TMC organic solution were 1 wt % and 3 min. The polyamide thin‐film composite membranes (EDA–TMC/mPAN) exhibited membrane durability when applied in the pervaporation separation of a 90 wt % isopropyl alcohol aqueous solution at 70°C, which indicated that the polyamide thin film composite (TFC) membranes were suitable for the pervaporation separation process at a high operating temperature. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Thermal degradation analysis of thermoset resins
Authors: Chatterjee Amit
Published: June 2009

Dynamic mechanical analysis, thermogravimetric analysis, and dielectric analysis (DEA) were conducted for three thermoset resin systems: bismaleimide, epoxy, and vinyl ester. The resin samples were subjected to various degrees of thermal exposure (400, 270, and 330°C for 5–150 min). Dielectric constants were measured along with the thermomechanical properties. The glass‐transition temperature, modulus, and weight loss were important parameters for correlating the material property changes with the heat exposure. A linear relation was determined between the thermomechanical properties and the dielectric properties of the resins under the selected exposure conditions. Therefore, DEA can be introduced as a significant technique for evaluating thermally exposed polymer materials. Interestingly, it is a nondestructive evaluation process. In the future, it could be used for onsite health monitoring of thermally exposed polymer matrix composite structures. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Influence of sulfuric acid bath on morphological structure and mechanical properties of poly(p‐phenylene‐1,3,4‐oxadiazole) fibers
Authors: Zhang Zaixing , Ye Guangdou , Li Wentao , Li Ting , Xu Jianjun
Published: June 2009

Poly(p‐phenylene‐1,3,4‐oxadiazoles) (p‐PODs) spinning solution was prepared by one‐step polycondensation, and p‐POD fibers were obtained by wet spinning method using dilute sulfuric acid as coagulation bath. The morphology and mechanical properties of p‐POD fibers under different coagulating conditions, such as bath concentration and temperature, were qualitatively and quantitatively studied by microscopes, ultrasonic orientation measurement, WAXD, and other traditional methods. The microscopic observation indicated that the p‐POD fibers were of three‐layer structure which consisted of outer skin, inner skin, and the core. The skin‐core structure and surface feature of the fibers were greatly affected by the coagulating conditions. At the same time, the results of WAXD and ultrasonic orientation measurement demonstrated that the crystallinity and orientation of the fibers also varied with the change of bath conditions. The tests of mechanical properties showed that the tensile strength, elongation at break, and maximum draw ratio of the p‐POD fibers were determined by their solid‐phase structures, which were largely influenced by coagulation conditions. According to the structure analysis and the mechanical tests, the optimal coagulation parameters were chosen to obtain p‐POD fibers with denser and more regular structure and better mechanical properties. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Transparency and wettability of PVP/PDMS‐IPN synthesized in different organic solvents
Authors: Hillerström Anna , Andersson Martin , Pedersen Jan Skov , Altskär Annika , Langton Maud , van Stam Jan , Kronberg Bengt
Published: June 2009

An interpenetrating polymer network (IPN) combining a hydrophobic polymer (polydimethylsiloxane, PDMS) and a hydrophilic polymer (polyvinylpyrrolidone, PVP) was synthesized in different solvents via a two‐step preparation method. The solvent used during polymerization of the IPN showed a significant impact on the properties of the PVP/PDMS‐IPN. The choice of solvent was affecting both the wettability and transparency of the PVP/PDMS‐IPN. The PVP/PDMS‐IPNs turned hydrophilic in all the solvents used in this study, but the transition from a hydrophobic to a hydrophilic PVP/PDMS‐IPN occurred at lower PVP concentration if a solvent with similar solubility parameter as PVP was chosen. Also, the PVP/PDMS‐IPNs were transparent when the samples were polymerized in a good solvent for PVP. It was concluded that the properties of the PVP/PDMS‐IPN can be tuned by the selection of the solvent used during polymerization. The size of the PVP phase domains in the PVP/PDMS‐IPNs were analyzed with X‐ray scattering techniques (SAXS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC), and the sizes of the domains were found to be smaller than 350 nm. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Adsorption of polyethylene from solution onto starch film surfaces
Authors: Fanta George F. , Salch John H. , Felker Frederick C. , Shogren Randal L.
Published: June 2009

We prepared starch films by jet‐cooking aqueous dispersions of high‐amylose starch and then allowing the jet‐cooked dispersions to air‐dry on Teflon surfaces. When the starch films were immersed in 1% solutions of polyethylene (PE) in 1‐dodecanol, dodecane, and xylene at 120°C and the solutions were allowed to slowly cool, PE precipitated from the solutions and adsorbed onto the starch film surfaces. Fourier transform infrared spectroscopy was used to estimate the micrograms of PE adsorbed per square centimeter of starch film. PE was preferentially adsorbed onto the film side that was in contact with the Teflon surface during drying. The amount of PE adsorbed ranged from about 8 to 45 μg/cm2 and depended upon the solvent used and the final temperature of the cooled solution. Scanning electron microscopy of the starch film surfaces showed discontinuous networks of adsorbed PE on the Teflon side and widely spaced nodules of adsorbed PE on the air side. NMR analysis showed that the PE adsorbed onto the starch surface was more linear and/or had a higher molecular weight than the starting PE. Possible reasons for the selective adsorption of PE onto the Teflon side of the starch film surface are discussed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Nylon 6 induced morphological developments and electrical conductivity improvements of polypropylene/carbon black composites
Authors: Chen Guangshun , Yang Bo , Guo Shaoyun
Published: June 2009

In this study, a polar conductive filler [carbon black (CB)], a nonpolar polymer [polypropylene (PP)], and a polar polymer [nylon 6 (PA6)] were chosen to fabricate electrically conductive polymer composites by melt blending and compression molding. The morphological developments of these composites were studied. Scanning electron microscopy results showed that in a CB‐filled PP/PA6 (CPA) composite, CB particles were selectively dispersed in PA6 phases and could make the dispersed particles exist as microfiber particles, which could greatly improve the electrical conductivity. The PA6 and CB contents both could affect the morphologies of these composites. The results of electrical resistivity measurements of these composites proved the formation of conductive networks. The resistivity–temperature behaviors of these composites were also studied. For CB‐filled PP (CP) composites, there were apparent positive temperature coefficient (PTC) and negative temperature coefficient (NTC) effects and an unrepeatable resistivity–temperature characteristic. However, for CPA composites, there were no PTC or NTC effects from room temperature to 180°C, and the resistivity–temperature behavior showed a repeatable characteristic; this proved that CB particles were selectively dispersed in the PA6 phase from another point of view. All experimental results indicated that the addition of PA6 to a CP composite could lead to an expected morphological structure and improve the electrical conductivity of the CP composite. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Controlling the deposition of light‐emitting nanofibers/microfibers by the electrospinning of a poly(p‐phenylene vinylene) polyelectrolyte precursor
Authors: Xin Yi , Huang Zonghao , Yang Peipei , Jiang Zijiang , Wang Cheng , Shao Chen
Published: June 2009

Poly(p‐phenylene vinylene) (PPV) nanofibers with disordered, helical, and yarn morphologies were controllably prepared by the electrospinning of a cationic polyelectrolyte precursor in an ethanol solution followed by thermal conversion. Through the tuning of the precursor solution properties and processing variables, the factors affecting the morphology of PPV fibers were studied. The diameter of these PPV nanofibers decreased with a decrease in the precursor concentration, and gradual blueshifts and changes in the relative intensity of the vibronic components in photoluminescence spectra were observed. These nanofibers with excellent fluorescent properties are potentially interesting for many applications such as micro‐ and nano‐optoelectronic devices and systems. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis and characterization of poly(dimethylamino ethyl methacrylate)–poly(ethylene oxide)–poly(dimethylamino ethyl methacrylate) triblock copolymers
Authors: Tong Dajun , Yao Jia , Wang Qing , Zhai Tao , Li Haoran , Han Shijun
Published: June 2009

Novel, monodispersed, and well‐defined ABA triblock copolymers [poly(dimethylamino ethyl methacrylate)–poly(ethylene oxide)–poly(dimethylamino ethyl methacrylate)] were synthesized by oxyanionic polymerization with potassium tert‐butanoxide as the initiator. Gel permeation chromatography and 1H‐NMR analysis showed that the obtained products were the desired copolymers with molecular weights close to calculated values. Because the poly(dimethylamino ethyl methacrylate) block was pH‐ and temperature‐sensitive, the aqueous solution behavior of the polymers was investigated with 1H‐NMR and dynamic light scattering techniques at different pH values and at different temperatures. The micelle morphology was determined with transmission electron microscopy. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Coating of polyelectrolyte multilayer thin films on nanofibrous scaffolds to improve cell adhesion
Authors: Dubas Stephan T. , Kittitheeranun Paveenuch , Rangkupan Ratthapol , Sanchavanakit Neeracha , Potiyaraj Pranut
Published: June 2009

The adhesion of L929 cells to poly(ϵ‐caprolactone) (PCL) nanofibers was successfully improved via coating with polyelectrolyte multilayer thin films (PEMs), which enhanced the potential of this material as a scaffold in tissue engineering applications. With the electrostatic self‐assembly technique, poly(diallyldimethylammonium chloride) (PDADMAC) and poly(sodium 4‐styrene sulfonate) (PSS) were formed as four‐bilayer PEMs on electrospun PCL nanofiber mats. Because PDADMAC and PSS are strong polyelectrolytes, they provided stable films with good adhesion on the fibers within a wide pH range suitable for the subsequent processes and conditions. PDADMAC and gelatin were also constructed as four‐bilayer PEMs on top of the PDADMAC‐ and PSS‐coated nanofibers with the expectation that the gelatin would improve the cell adhesion. L929 cells from mouse fibroblasts were then seeded on both uncoated and coated scaffolds to study the cytocompatibility and in vitro cell behavior. It was revealed by the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay that both the uncoated and coated nanofiber mats were nontoxic as the cell viability was comparable to that of those cultured in the serum‐free medium that was used as a control. The MTT assay also demonstrated that cells proliferated more efficiently on the coated nanofibers than those on the uncoated ones during the 48‐h culture period. As observed by scanning electron microscopy, the cells spread well on the coated nanofibers, especially when gelatin was incorporated. The surface modification of PCL nanofiber mats described in this research is therefore an effective technique for improving cell adhesion. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009