bluuebunny/crossref_metadata_2025 huggingface dataset:
Measuring use of services for mental health problems in epidemiological surveys
Authors: Sevilla‐Dedieu Christine , Kovess‐Masfety Viviane , Angermeyer Matthias , Bruffaerts Ronny , Fernandez Anna , De Girolamo Giovanni , De Graaf Ron , Haro Josep Maria , König Hans‐Helmut ,   The ESEMED/MHEDEA 2000 Investigators
Published: August 2011

The use of services for mental problems is generally reported as being relatively low. However, the methods used for data collection in surveys may have influenced the quality of self‐reported service use. This study compares the information on recourse to physicians for mental problems reported in different sections of a survey conducted in six European countries. Thus, 5545 respondents were asked questions on contacts with physicians at least twice: (1) after the symptoms checklist in any completed diagnostic section, and (2) in a section devoted to use of care for mental problems. Of these 39.3% reported contacts with physicians about mental problems in the diagnostic sections, whereas 29.5% did so in the use‐of‐care section. Inconsistencies concerned 20.1% of participants, among whom those reporting consultations in diagnostic sections without reporting them in the use‐of‐care section represented the majority (74.4%). Multiple logistic regression analysis revealed that age, marital status, educational level and country were associated with under‐reporting in the use‐of‐care section, as well as having mood or sleep problems. In conclusion, services used for mental health reasons when measured through a question referring to use of care due to the presence of a mental problem may underestimate the care people received for their problems. Copyright © 2011 John Wiley & Sons, Ltd.
Hybrid prospective and retrospective head motion correction to mitigate cross‐calibration errors
Authors: Aksoy Murat , Forman Christoph , Straka Matus , Çukur Tolga , Hornegger Joachim , Bammer Roland
Published: August 2011

Utilization of external motion tracking devices is an emerging technology in head motion correction for MRI. However, cross‐calibration between the reference frames of the external tracking device and the MRI scanner can be tedious and remains a challenge in practical applications. In this study, we present two hybrid methods, both of which combine prospective, optical‐based motion correction with retrospective entropy‐based autofocusing to remove residual motion artifacts. Our results revealed that in the presence of cross‐calibration errors between the optical tracking device and the MR scanner, application of retrospective correction on prospectively corrected data significantly improves image quality. As a result of this hybrid prospective and retrospective motion correction approach, the requirement for a high‐quality calibration scan can be significantly relaxed, even to the extent that it is possible to perform external prospective motion tracking without any prior cross‐calibration step if a crude approximation of cross‐calibration matrix exists. Moreover, the motion tracking system, which is used to reduce the dimensionality of the autofocusing problem, benefits the retrospective approach at the same time. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.
Analysis and correction of background velocity offsets in phase‐contrast flow measurements using magnetic field monitoring
Authors: Giese Daniel , Haeberlin Maximilian , Barmet Christoph , Pruessmann Klaas P. , Schaeffter Tobias , Kozerke Sebastian
Published: August 2011

The value of phase‐contrast magnetic resonance imaging for quantifying tissue motion and blood flow has been long recognized. However, the sensitivity of the method to system imperfections can lead to inaccuracies limiting its clinical acceptance. A key source of error relates to eddy current‐induced phase fluctuations, which can offset the measured object velocity significantly. A higher‐order dynamic field camera was used to study the spatiotemporal evolution of background phases in cine phase‐contrast measurements. It is demonstrated that eddy current‐induced offsets in phase‐difference data are present up to the second spatial order. Oscillatory temporal behaviors of offsets in the kHz range suggest mechanical resonances of the MR system to be non‐negligible in phase‐contrast imaging. By careful selection of the echo time, their impact can be significantly reduced. When applying field monitoring data for correcting eddy current and mechanically induced velocity offsets, errors decrease to less than 0.5% of the maximum velocity for various sequence settings proving the robustness of the correction approach. In vivo feasibility is demonstrated for aortic and pulmonary flow measurements in five healthy subjects. Using field monitoring data, mean error in stroke volume was reduced from 10% to below 3%. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.
Is on‐demand sacral neuromodulation in patients with OAB syndrome a feasible therapy regime?
Authors: Oerlemans Dennis J.A.J. , van Voskuilen Anco C. , Marcelissen Tom , Weil Ernest H.J. , de Bie Rob A. , Van Kerrebroeck Philip E.V.
Published: August 2011

Introduction

Sacral neuromodulation (SNM) of the lower urinary tract has proven to be safe and effective in patients with complaints of OAB syndrome who are not responding to conservative therapy. After 5 years of treatment the implanted system is still effective in 56–71% of patients. The loss of effect could be caused by adaptation of the nerve system to prolonged stimulation of the sacral nerves.

Materials and Methods

We set up a pilot intervention study. After a run‐in period of 2 weeks patients were randomized into two groups: one group with on‐demand neuromodulation (intervention group) and one group with continuous neuromodulation (control group). Patients in the intervention group were instructed to switch their INS off by default and to switch it on again when they felt recurrent symptoms, patients in the control group were asked to use their system as normally.

Results

After 2 weeks 10 out of 16 subjects reported a comparable symptom score during on‐demand use of their neuromodulation system. Patients appreciated the comfort of being self‐determent in the need for therapy.

Conclusions

Possible benefits for patients could be: more autonomy, longer battery life of the implanted INS, decreasing the chance of adaptation by the nervous system. Neurourol. Urodynam. Neurourol. Urodynam. 30: 1493–1496, 2011. © 2011 Wiley Periodicals, Inc.
Prevalence, risk factors, and impact on health related quality of life of overactive bladder in China
Authors: Wang Yuliang , Xu Kexin , Hu Hao , Zhang Xiaopeng , Wang Xiaofeng , Na Yanqun , Kang Xiaoping
Published: August 2011

Aims

To evaluate the prevalence, associated risk factors and the impact on health related quality of life (HRQoL) of overactive bladder (OAB) among men and women aged ≥18 years in China, using the 2002 International Continence Society (ICS) definition.

Methods

The population‐based, cross‐sectional field survey was conducted between June 2009 and February 2010 in China using questionnaires regarding demographics, the prevalence and the HRQoL. A stratified random sample of men and women aged ≥18 years residing in China who were representative of the general populations was selected for demographic questionnaires first. The individuals meeting the diagnostic criteria of OAB (urgency occurring once a week or more) were further interviewed through King's health questionnaire (KHQ) to estimate the impact of OAB on HRQoL. Data were stratified by city, age cohort, and gender.

Results

A total of 21,513 individuals were contacted to participate in the survey, and 14,844 individuals (7,614 men, 7,230 women) with complete data were included in this study. The prevalence of OAB was 6.0%, OABdry 4.2%, and OABwet 1.8%. The prevalence varied slightly among six geographical regions of China. Nocturia was the most common OAB symptom besides urgency. Advanced age, higher BMI, lower education level, manual worker, alcohol consumption, and married were associated risk factors for OAB in men. Advanced age, lower education level, manual worker, alcohol consumption, married, menopause, more parities and vaginal delivery were potential risk factors for OAB in women. The symptoms of OAB had a detrimental effect on HRQoL, especially on Coping Measures, Sleep/Energy, General Health Perceptions, and Severity of Urinary Problems.

Conclusions

The prevalence of OAB in China is lower than that of most previous reports. Many known risk factors are associated with OAB. The symptoms of OAB have a detrimental effect on HRQoL. Efforts need to be made to improve public and professional education about the problems of OAB and decrease the unnecessary burden of this condition. Neurourol. Urodynam. Neurourol. Urodynam. 30: 1448–1455, 2011. © 2011 Wiley Periodicals, Inc.
Short‐term effects of systematized behavioral modification program for nocturia: A prospective study
Authors: Cho Sung Yong , Lee Sang Lim , Kim In Sung , Koo Dong Hun , Kim Hyeon‐jun , Oh Seung‐June
Published: August 2011

Aims

This study is to investigate whether a repetitive education program for behavioral modification is necessary for the patients with nocturnal polyuria (NPU).

Materials and Methods

A prospective single‐arm study was carried out and 82 patients with NPU were analyzed. We developed a 30‐min systematized behavioral modification program (SBMP), which consisted of (1) watching videos about normal physiology of storing and emptying function of urine, (2) regulation of fluid intake, (3) explanation by giving specific examples, and (4) discussion with a specialized nurse practitioner. Patients received reinforcement SBMP if they still had NPU after the first SBMP.

Results

Mean age was 66 ± 8.3 years. Sixty‐three males (77%) and 19 females (23%) were included. The results of all questionnaires showed significant improvement of nocturia after the first SBMP. Nocturnal voids, quality of life scores, nocturia index, and nocturnal bladder capacity index were significantly improved and the decrease of nocturnal urine volume was borderline significant. No additional significant improvement was demonstrated after the second SBMP. Overall, 62 patients (78.5%) were satisfied with the first SBMP and 6 patients (7.6%) became satisfied after reinforcement SBMP. Eleven patients (13.9%) were eventually dissatisfied with SBMP.

Conclusions

A single SBMP was sufficient for treating most of the patients with NPU and reinforcement SBMP was effective in some patients. Moving from two to one rises at night may significantly reduce bother and this may explain quality of life improvements rather than any decrease in amount voided. Neurourol. Urodynam. 31:64–68, 2012. © 2011 Wiley Periodicals, Inc.
Stroke with transfusions changing to hydroxyurea (SWiTCH): A phase III randomized clinical trial for treatment of children with sickle cell anemia, stroke, and iron overload
Authors: Ware Russell E. , Schultz William H. , Yovetich Nancy , Mortier Nicole A. , Alvarez Ofelia , Hilliard Lee , Iyer Rathi V. , Miller Scott T. , Rogers Zora R. , Scott J. Paul , Waclawiw Myron , Helms Ronald W.
Published: August 2011

Background

Stroke occurs in 5–10% of children with sickle cell anemia (SCA) and has a high (>50%) risk of recurrence without therapy. Chronic monthly erythrocyte transfusions effectively prevent recurrent stroke, but their long‐term use is limited by serious side effects, including iron overload. An alternative to transfusion for secondary stroke prevention in SCA is needed, especially one that also improves the management of iron overload.

Methods

Stroke With Transfusions Changing to Hydroxyurea (SWiTCH) is an NHLBI‐sponsored Phase III multicenter randomized controlled clinical trial for children with SCA, stroke, and iron overload (NCT00122980). The primary goal of SWiTCH is to compare 30 months of alternative therapy (hydroxyurea and phlebotomy) with standard therapy (transfusions and chelation) for the prevention of secondary stroke and reduction of transfusional iron overload.

Discussion

SWiTCH has several distinctive study features including novel methodological and design components: (1) composite primary endpoint including both stroke recurrence rate and iron burden; (2) non‐inferiority design with an “acceptable” increased stroke risk; (3) transfusion goals based on current academic community practices; (4) special oversight for the enrollment and randomization process; (5) overlap treatment period within the alternative treatment arm; (6) masking of the overall trial Principal Investigator to treatment results; (7) inclusive independent stroke adjudication process for all suspected new neurological events; and (8) periodic therapeutic phlebotomy program to alleviate iron overload.

Conclusion

Investigation of alternative treatments in SWiTCH could lead to changes in the management of cerebrovascular disease for selected patients with SCA, stroke, and iron overload. Pediatr Blood Cancer 2011; 57: 1011–1017. © 2011 Wiley‐Liss, Inc.
Does surgery have a role in the treatment of local relapses of non‐metastatic rhabdomyosarcoma?
Authors: De Corti Federica , Bisogno Gianni , Dall'Igna Patrizia , Ferrari Andrea , Buffa Piero , De Paoli Angela , Cecchetto Giovanni
Published: August 2011

Purpose

Patients with non‐metastatic rhabdomyosarcoma (RMS) have a cure rate of 50–90%, but up to one‐third of them experience mostly a local recurrence. Second‐line treatment is not standardized as for newly diagnosed tumors. We evaluated the role of surgery on local relapses in a series of patients with RMS.

Methods

This retrospective analysis involves 70 patients enrolled in two consecutives Italian Studies, RMS88 and RMS96, who presented local recurrence. After relapse, 40/70 underwent a surgical excision (Surgery Group, SG), that was demolitive in 10/40; 24/40 had radiotherapy, 16/40 did not receive radiotherapy or data are not known. Thirty patients out of 70 did not receive any surgical treatment (No‐Surgery Group, NSG), and 20/30 received radiotherapy.

Results

Overall survival (OS) after local relapse was 41.6% (mean follow‐up 59 months, range 1–226). OS of SG patients was 54% versus 24.7% of the NSG patients (P = 0.0117). Furthermore, OS among the SG was 61.4% with and 41.8% without radiotherapy, and 37.1% with and 0% without radiotherapy among the NSG (P < 0.0001). One patient developed a second local relapse after excision without radiotherapy for the first one, and was cured with further treatment. Demolitive surgery did not improve survival compared to conservative surgery (40% vs. 58.4%, P = 0.1462).

Conclusion

The treatment of recurrent RMS represents a challenge. In our experience, patients with local relapse had a poor prognosis. SG patients had a better outcome than NSG patients and those treated with resection plus radiotherapy had the best outcome; patients who did not receive any local treatment had an unfavorable outcome. Pediatr Blood Cancer 2011; 57: 1261–1265. © 2011 Wiley Periodicals, Inc.
Impact of PET‐CT on involved field radiotherapy design for pediatric Hodgkin lymphoma
Authors: Paulino Arnold C. , Margolin Judith , Dreyer ZoAnn , Teh Bin S. , Chiang Stephen
Published: August 2011

Purpose

To determine how the incorporation of PET‐CT changes radiotherapy treatment in pediatric Hodgkin lymphoma.

Procedure

Fifty‐three Hodgkin lymphoma patients with a median age of 14 years (6–21 years) underwent multiagent chemotherapy followed by involved field radiotherapy (IFRT) to initial sites of disease. All patients had conventional staging which included CT scan of the neck, chest, abdomen and pelvis, bone marrow biopsy ± MRI, Gallium scan and bone scan. All had an initial 18‐F‐fluoro‐deoxy‐D‐glucose (FDG) PET‐CT. When there was discordance between conventional staging and PET‐CT staging, true sites of disease were determined either by biopsy or response to multiagent chemotherapy.

Results

In 19 of 53 (35.8%) patients, there was discordance between conventional staging and PET‐CT findings. The most common location for the 23 sites of discordance were the spleen in 6 (26.1%), neck in 3 (13%), inguinal nodes in 3 (13%) and mediastinum in 3 (13%). A change in stage occurred in 5 (9.4%) as a result of PET‐CT imaging. A change in IFRT fields occurred in 9 (17%); eight were more extensive while one was less extensive. For PET‐CT, the specificity, sensitivity, positive predictive value and accuracy were 99.5%, 96.3%, 97.9%, and 98.9%.

Conclusion

Incorporation of PET‐CT information was found to influence IFRT design in 17% of patients, with most having more extensive radiotherapy fields. Pediatr Blood Cancer 2012; 58: 860–864. © 2011 Wiley Periodicals, Inc.
Polymer–cement composite based on recycled expanded polystyrene foam waste
Authors: Eskander S.B. , Tawfik M.E.
Published: August 2011

A new polymer–cement composite based on a recycled expanded polystyrene (EPS) resin has been developed as an effective method for EPS foam wastes management. The liquefied polymer is prepared by dissolving the foam waste in acetone, then in toluene at the ratio 113:2:1 per volume, respectively. The composite is made by incorporating the resulting resin into cement‐paste at selected water:cement ratios. At the end of defined curing periods, the physical, mechanical, and thermal characterizations of the obtained composite were evaluated under variable factors e.g., Acetone: toluene ratio, water:cement ratio (w/c), curing periods. Compressive strength, apparent porosity, bulk density, and specific gravity were determined for the composite under the various stated conditions. FT‐IR, XRD, thermal analysis, and scanning electron microscope (SEM) were performed for the hard blocks to study the effect of the added recycled EPS resin on the microstructure of the end products. Based on the data so far obtained it can be concluded that the candidate dissolution process of EPS foam wastes is an easily environmental friendly technique that allows afterward using the resultant resin for producing an added value, low cost, promising market competitive, and multipurpose light weight cement composite. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
Effect of the resin/hardener ratio on yield, post‐yield, and fracture behavior of nanofilled epoxies
Authors: Pandini Stefano , Baldi Francesco , De Santis Riccardo , Bignotti Fabio
Published: August 2011

In this work, the effect of the resin/hardener ratio on the small deformation, yield, post‐yield, and fracture behavior of a series of DGEBA‐Jeffamine epoxy‐clay nanocomposites with a fixed organo‐clay content (6 phr), and of the corresponding unfilled resins, was investigated. The mechanical behavior at small deformation was studied by means of uniaxial tensile tests, whereas compression tests were employed to investigate the large (yield and post‐yield) deformation levels. The fracture behavior was studied by the application of fracture mechanics testing methods. The results pointed out that small variations in the resin/hardener ratio used for the preparation of the resin can give rise to remarkable differences in the mechanical behavior at large deformation levels and at fracture. These effects were related to the parameters characteristic of the macromolecular architecture of the resins (chain segments flexibility and crosslink density). The results obtained on nanofilled systems showed that the effect of the resin/hardener ratio on the mechanical behavior of the resins is reduced in presence of organoclay particles. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
The effect of interface debonding behaviors on the mechanical properties of microPCMs/epoxy composites
Authors: Wang Xin‐Yu , Su Jun‐Feng , Wang Sheng‐Bao , Zhao Yun‐Hui
Published: August 2011

Microcapsules containing phase change materials (microPCMs) can be filled in polymeric matrix forming smart temperature‐controlling composites. The aim of this study was to investigate the relationship between the interface behaviors and the mechanical properties of methanol‐melamine‐formaldehyde shell microPCMs containing paraffin/epoxy matrix composites. The typical microPCMs with core/shell ratio of 2/1 shapely decreased their average diameter from 26.0 ± 1.5 to 13.8 ± 3.4 μm with the increasing of stirring speed from 1,000 to 3,000 r min−1. But, both the thickness and yield point of shells had a little variation. Young's modulus of composites was almost independent on the particle size of microPCMs with lower volume fractions (5%–10%). For composites with higher microPCMs loading (20%–30%), there was a slight decrease in modulus with increasing particle size. The data of tensile strength decreased obviously with the increasing of the average diameter of microcapsules for composite samples with the same particle loading. A repeated heat‐transmission treatment was applied to enhance the interface debonding. The results show that the violent thermal transmission had decreased the mechanical properties of microPCMs/epoxy composites. The scanning electron microscopy morphologies had also proved that these phenomena attributed to the interphase separation and cracks. Moreover, a semiexperiential conclusion is that the increasing of interface area of composites will at the same time give more structure defects leading to poor mechanical properties. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
Investigation of the crystalline structure of PVDF in PVDF/PMMA/graphene polymer blend nanocomposites
Authors: Mohamadi S. , Sharifi‐Sanjani N.
Published: August 2011

In this work, we report the preparation of poly(vinylidene fluoride)/poly methylmethacrylate (PVDF/PMMA)/graphene polymer blend nanocomposites via synthesis of PMMA/graphene as a masterbatch through in situ polymerization. The PMMA/graphene masterbatch compounded with PVDF by solution mixing in different ratios. The compounding was followed by solution casting to form polymer blend nanocomposites. Solution cast films were subjected to thermal treatments at three different temperatures. The crystalline structure of thermally treated samples was studied with X‐ray diffraction spectroscopy and Differential Scanning Calorimetric (DSC) analysis. Results indicated PMMA chains persuade the β crystalline form in PVDF but cannot stabilize them in elevated temperature; however, graphene sheets due to restricting effect on TT conformation chains are able to stabilize them. DSC data revealed the graphene sheets can increase the crystallinity of PVDF and also act as nucleating agents. Transmission Electron Microscopy demonstrated coexistence of the different stacking orders of graphene sheets in both masterbatch and polymer blend nanocomposite. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
Relationship between cardiovascular outcomes and proton pump inhibitor use in patients receiving dual antiplatelet therapy after acute coronary syndrome
Authors: Hsiao Fei‐Yuan , Mullins C. Daniel , Wen Yu‐Wen , Huang Weng‐Foung , Chen Pei‐Fen , Tsai Yi‐Wen
Published: August 2011

Background

There is conflicting evidence regarding the potential interaction between clopidogrel and proton pump inhibitors (PPIs), with observational studies suggesting an increased risk of adverse cardiovascular (CV) outcomes and clinical trials suggesting there is no such risk.

Methods

We conducted a retrospective cohort study to assess CV outcomes of 9753 patients taking dual antiplatelet therapy of aspirin plus clopidogrel with or without a PPI after hospitalization for acute coronary syndrome (ACS). Cox proportional hazards models were used to assess our primary endpoint of re‐hospitalization for ACS in overall sample and a propensity score matching subsample.

Results

Among patients taking clopidogrel plus aspirin, concomitant use of PPI was not associated with the risk of re‐hospitalization for ACS (adjusted hazard ratio [HR] 1.12 [95%CI 0.72–1.73]). The findings were consistent in the propensity score matching cohort (adjusted HR 0.82 [95%CI 0.43–1.54]). Compared with PPI nonusers, there is no significant association between each specific PPI users and the risk of re‐hospitalization for ACS (adjusted HR; omeprazole 0.96 [95%CI 0.35–2.66], pantoprazole 1.05 [95%CI 0.38–2.92], rabeprazole 0.60 [95%CI 0.17–2.17], esomeprazole 0.31 [95%CI 0.10–0.99], and lansoprazole 0.82 [95%CI 0.32–2.07]).

Conclusion

In conclusion, this population‐based cohort study found that concomitant use of clopidogrel and PPI in patients who received dual antiplatelet therapy after ACS was not associated with risk of ACS re‐hospitalization. Together, our study and findings of recently published clinical trials suggest that there was no apparent CV interaction between clopidogrel and PPI in patients who received dual antiplatelet therapy. Copyright © 2011 John Wiley & Sons, Ltd.
Miscibility and crystallization of biodegradable poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate)/poly(vinyl phenol) blends
Authors: Cai Haoyuan , Yu Jing , Qiu Zhaobin
Published: August 2011

Miscibility and crystallization of biodegradable poly (3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) (PHBHHx)/poly(vinyl phenol) (PVPh) blends were investigated in this work. PHBHHx is miscible with PVPh over the whole composition range as evidenced by the single composition dependent glass transition temperature and the depression of equilibrium melting point of PHBHHx in the blends. The overall crystallization rates decrease with increasing crystallization temperature for both neat PHBHHx and its blends with PVPh; moreover, the overall crystallization rates are slower in the PHBHHx/PVPh blends than in neat PHBHHx at the same crystallization temperature. Blending with PVPh may change the crystallization mechanism of PHBHHx in the blends compared with that of neat PHBHHx. Both neat PHBHHx and the PHBHHx/PVPh blends exhibit a crystallization regime II to III transition. The crystal structure of PHBHHx is not modified in the PHBHHx/PVPh blends; however, the values of crystal layer thickness, amorphous layer thickness, and long period all become larger with increasing PVPh content in the blends. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers
Apparent volumetric shrinkage study of RTM6 resin during the curing process and its effect on the residual stresses in a composite
Authors: Magniez K. , Vijayan Arun , Finn Niall
Published: August 2011

A comprehensive characterization of the volumetric shrinkage of a commercially important aerospace resin (RTM6) during the various stages of the curing process was studied. The apparent volumetric shrinkage, evaluated from density measurements at room temperature, was correlated with the progress of epoxide conversion. During the entire curing process, the apparent volume shrinkage was found to be less than 3% and occurred before vitrification. A slight re‐expansion of the resin, attributed to self‐antiplasticization effects, was observed during postcuring at 180°C. It was concluded that residual stresses were not generated due to chemical cross‐linking during curing but rather from thermal contraction occurring during the cooling stage after cure. A photo‐elastic method was used to characterize residual stresses during cooling in a deliberately engineered resin rich hole of a carbon fiber/RTM6 composite. The residual stress was found to reach approximately 28 MPa, which is in good agreement with the value calculated from the shrinkage and elastic moduli. It is proposed that this simple method can be provide insights useful to the design and materials selection processes by measuring and localizing residual stresses from resin during curing and or thermal cycling. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers
Isothermal and non‐isothermal crystallization behavior of PET nanocomposites
Authors: Ghasemi Hesam , Carreau Pierre J. , Kamal Musa R.
Published: August 2011

Polyethylene terephthalate (PET)/clay nanocomposites (PCNs) containing 1 wt% Cloisite 30B (C30B) were prepared via melt compounding. Modulated differential scanning calorimetry (MDSC) for isothermally crystallized samples revealed that the third endotherm at the highest temperature may be attributed to the recrystalization and melting of crystals, reorganized during heating. The first and second endotherms may be associated with melting of the secondary and primary crystals, respectively. The overall isothermal crystallization rate in PCNs was faster than in the neat resin. Growth kinetics revealed that the work required for chain folding and the equilibrium melting temperature in PCNs were somewhat higher than for neat PET. During isothermal crystallization, the steric hurdles introduced by clay layers lead to a reduction in the transport of the PET chains into crystallites. The effective non‐isothermal activation energy for the PCNs was higher than for PET, possibly leading to less perfect crystals in the PCNs. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers
Relationship between the distribution of organo‐montmorillonite and the flammability of flame retardant polypropylene
Authors: Chen Yajun , Guo Zhenghong , Fang Zhengping
Published: August 2011

This article studies the relationship between the distribution of organically modified montmorillonite (OMMT) and the flammability of flame retardant polypropylene which consists of polypropylene (PP), brominated epoxy resin‐antimony oxide (BER‐AO) and OMMT. Polypropylene‐graft‐maleic anhydride (PP‐g‐MAH) was used to increase the polarity of PP and aid the dispersion of OMMT. Two model systems, PP/BER‐AO/OMMT and PP/PP‐g‐MAH/BER‐AO/OMMT composites, have been prepared by melt blending. TEM studies reveal a significant change in the distribution of OMMT for these two systems. For the first composites, OMMT platelets are aggregated in the BER‐AO domains, whereas for the second composites, OMMT platelets are dispersed in the PP matrix. The flame retardant properties of the second composite reflected by UL 94 vertical burning test and cone calorimetry are better than that of the first one. When OMMT platelets aggregate in BER‐AO domains as in the first composite, the BER‐AO associated with OMMT may agglomerate into long ribbon‐like structures during burning, inducing uneven distribution of BER‐AO. As a result, loose and uneven residues are formed at the end of combustion. In comparison, OMMT platelets dispersed in polymer matrix are more efficient at stabilizing the polymer and preventing aggregation of BER‐AO during burning, which induce thick and uniform char layers at the end of combustion. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers
Preparation of a structured acrylic impact modifier and its application in toughening polyamide 6
Authors: Zhao Haiyan , Yao Yanmei , Liu Xinran , Zhang Qingxin , Wang Nongyue , Zhang Liqun , Qu Xiongwei
Published: August 2011

A series of poly(n‐butyl acrylate)/poly(methyl methacrylate‐co‐acrylic acid), i.e., poly(BA/MMA‐co‐AA), core‐shell structured modifiers with different contents of crosslinking agent allyl methacrylate and functional monomer were prepared, and its effects on mechanical properties of polyamide 6 (PA 6) blends were investigated. The modifiers were prepared at a solid content of 50 wt% by a seeded emulsion polymerization. Dynamic light scattering measurement showed that the particle grew without significant secondary nucleation occurring. The morphology was confirmed by means of transmission electron microscopy. Scanning electron microscopy was used to observe the morphology of the fractured surfaces. The dynamic mechanical analysis measurements indicated that the appearance of two merged transition peaks and the magnitude of the loss peak of PA 6 matrix with the addition of PBMA core‐shell modifier in the PA 6/PBMA blends were responsible for the improvement of PA 6 toughness. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers
Thermal behavior of poly(ethylene‐co‐propylene) containing carbon nanofibers
Authors: Adhikari A.R. , Georgiev G. , Sigdel K. , Iannacchione G.S. , Lozano K. , Chipara M.
Published: August 2011

The effect of carbon nanofiber on the thermal behavior of poly(ethylene‐co‐propylene) (PEP) as revealed by differential scanning calorimetry and thermogravimetric analysis is reported. Analysis showed faster crystallization of PEP at higher temperature upon cooling with the increase of carbon nanofiber (CNF) content. The crystallization behavior changed to a single narrow crystallization peak as compared with the broad double crystallization peak of the neat polymer. This demonstrates the nucleation ability of CNF to induce crystals with more uniform distribution. The modified‐Avrami approach was used to study the crystallization behavior. We found that the crystallization rate constant increased with addition of CNFs. The dimensionality of crystal growth was found not to depend significantly on the content of CNF. Thermal degradation in air was monitored using thermogravimetric analysis and observed that the incorporation of nanofiber greater than 2.4 vol% improves thermal stability of PEP. All these results indicate that CNFs can significantly help polymer processing and increase thermal stability of polymers. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers
In‐situ real‐time monitoring of particle size, polymer, and monomer contents in emulsion polymerization of methyl methacrylate by near infrared spectroscopy
Authors: Silva Wandeklebio K. , Chicoma Dennis L. , Giudici Reinaldo
Published: August 2011

This work reports the results of in‐situ real‐time monitoring of the emulsion polymerization of methyl methacrylate by near infrared spectroscopy (NIRS) under different feed conditions. Besides the monitoring of the monomer and polymer content, the results show that reasonable estimates can be obtained from the spectra for the average particle size of the growing polymer particles present in the reaction medium. This is possible because the presence of the particles affects the spectra (through scattering, diffraction, and other mechanisms). Thus, by using appropriate calibration, it is possible obtain reliable models for particle size, in addition to monitoring the monomer and polymer concentrations. Experimental results for emulsion polymerizations conducted with various feed monomer conditions indicated that, in the spectral range studied, it is not only possible to monitor the evolution of the monomer and polymer contents, but also to follow the changes in the average size of the polymer particle. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Test procedures for maximum power point tracking charge controllers characterization
Authors: Camino‐Villacorta María , Egido‐Aguilera Miguel Angel , Díaz Pablo
Published: August 2011

Photovoltaic stand‐alone systems (PVSAS) are the most widespread technology for rural electrification of off‐grid areas, for communication systems, and for satellite applications. Such applications require high reliability to guarantee an adequate electrical supply. In these systems, charge controllers and inverters are used to fit the PV output power to the load. The power adaptation stage is essential to the proper performance of the PVSAS and to the optimization of the energy management of the system. However, there are no international standards yet approved that cover the quality requirements of this stage. This paper deals with the performance of those charge controllers that use maximum power point tracking algorithms. The aim of this work is to define the specific parameters that describe the real performance of these controllers, paying attention to their static and dynamic efficiency and establishing the acceptable minimum thresholds required for each one. A set of measurements of three commercial controllers was developed. Their behavior in real varying conditions was monitored along 1 year of operation. Results are presented here after being checked with repetitive indoor measurements using a PV array simulator. Main results of the operation in a PVSAS are included in the paper for selected representative days along the year. To perform the daily analysis, we have classified each day according to its weather conditions. The purpose is to analyze the relation between the performance of the controller and the weather variations. Within the conclusions of this work, some guidelines for the definition of test procedures for maximum power point tracking charge controllers are included. Copyright © 2011 John Wiley & Sons, Ltd.
Focussed ion beam and field emission gun–scanning electron microscopy for the investigation of voiding and interface phenomena in thin‐film solar cells
Authors: Major Jonathan D. , Bowen Leon , Durose Ken
Published: August 2011

The use of focussed ion beam milling combined with high resolution scanning electron microscopy analysis as a characterisation tool for thin‐film photovoltaics is reported. CdTe solar cell cross sections are examined in high detail with as‐grown and CdCl2‐treated devices being compared. Observed changes in microstructure of the thin‐film layers are related to the device performance. The CdCl2 treatment is shown to cause a reduction in the CdTe defect density at regions close to the interface and induce recrystallization of the CdS layer. Furthermore, the focussed ion beam technique is shown to reveal voids formed within the device's thin‐film layers at various processing stages that have not been previously observed in working cell structures. The back‐contacting Te‐rich layer resulting from nitric–phosphoric acid etching is also observed, with the etched layer being seen to propagate down the CdTe grain boundaries. Copyright © 2011 John Wiley & Sons, Ltd.
Quality of life and mental health in the bereaved family members of patients with terminal cancer
Authors: Song Jong Im , Shin Dong Wook , Choi Jin‐Young , Kang Jina , Baek Young‐Ji , Mo Ha‐Na , Seo Min‐Jeong , Hwang Yun Hee , Lim Yeun‐Keun , Lee Ok Kyoung
Published: August 2011

Objective

This study specifically aimed to compare quality of life (QOL) and mental health in bereaved family members of patients with cancer with that of the general population and to examine factors associated with QOL and mental health in this population.

Design

A nationwide multicenter, cross‐sectional survey was administered to the bereaved family members of patients with terminal cancer.

Setting

Thirty‐three palliative care centers designated by the Ministry of Health and Welfare participated in this study.

Participants

The participants in this study were 501 bereaved family members of patients with terminal cancer and matched control individuals from the Korean National Health and Nutrition Examination Survey.

Measurement

EQ‐5D and several questions used in Korean National Health And Nutrition Examination Survey were used in to measure health‐related QOL and mental health.

Results

Health‐related QOL, as determined by EQ‐5D, was significantly lower in bereaved family members than in controls (0.88 ± 0.20 vs 0.93 ± 0.13, p = 0.002). Bereaved family members experienced more frequent episodes of depression (33.1% vs 12.5%, p < 0.001) and suicidal thoughts (31.4% vs 16.4%, p < 0.001) during the previous year than did controls. Female sex, lower income, spousal relationship, and longer duration of survival after palliative care referral were negatively correlated with health‐related QOL. Younger age and higher mental burden of caregiving were associated with a higher risk of impaired mental health.

Discussion

Our results confirm that bereaved family members of patients with cancer have lower health‐related QOL and mental health than the general population. Healthcare providers should focus more attention on this vulnerable group, and various support programs should be developed to improve their health‐related QOL. Copyright © 2011 John Wiley & Sons, Ltd.
Psychometric properties of the Chinese version of Sense of Coherence Scale in women with cervical cancer
Authors: Ding Yan , Bao Lei‐Ping , Xu Hao , Hu Yan , Hallberg Ingalill Rahm
Published: August 2011

Purpose

The purpose of this study was to test the psychometric properties of a Chinese version of the Sense of Coherence Scale (C‐SOC‐13) in women with cervical cancer in Mainland China.

Methods

The C‐SOC‐13 and Health‐related Quality of Life scale (Functional Assessment of Cancer Therapy‐Cervix) were administered to 238 women with cervical cancer. Validity was assessed in terms of factor validity, predictive validity, divergent validity and stability, whereas reliability was evaluated using Cronbach's alpha coefficient.

Results

This study showed that in confirmatory factor analysis, the first‐order interrelated three‐factor model and second‐order model were performed based on Antonovsky's theoretical structure of Sense of Coherence (SOC). Both models fitted the data satisfactorily when the largest modification index was released. The chi‐square value/degrees of freedom was 2.120, the goodness‐of‐fit index was 0.919, the root mean square error of approximation was 0.069, and the comparative fit index was 0.911. The Pearson correlation coefficient between SOC and Functional Assessment of Cancer Therapy‐Cervix was 0.611. Enter multiple regression with SOC as a dependent variable and medical and socio‐economic variables as independent variables showed no statistically significant partial coefficient of any independent variable in regression equation except for age. The Cronbach's alpha coefficient for the scale was 0.824.

Conclusion

The factor validity, predictive validity and divergent validity of C‐SOC‐13 were reasonable, as well as the internal consistency. In general, C‐SOC‐13 showed to be suitable as an SOC measurement for women with cervical cancer in Mainland China. However, SOC may have a different meaning to Chinese people because of the philosophy and culture that shape the context of their lives. Generalizing the findings to other populations requires further psychometric evaluation of C‐SOC‐13. Further longitudinal studies are also needed to explore the stability. Copyright © 2011 John Wiley & Sons, Ltd.
The use of cyclic perfluoroalkanes and SF6 in atmospheric dispersion experiments
Authors: Martin D. , Petersson K. F. , Shallcross D. E.
Published: August 2011

The study of atmospheric dispersion has become increasingly important over the last 120 years or so. Research in exposure pathways, fate of pollutants, dispersion model evaluation and validation are all reliant on experimental data. The most common atmospheric tracer compounds in use at the present time are the cyclic perfluoroalkanes and sulphur hexafluoride. These compounds are non‐toxic, non‐reactive and have low atmospheric background concentrations although they are recognized as greenhouse gases. This review discusses their use relative to other tracer species. A brief history of their individual analyses is included. The review then seeks to give a concise description of some representative atmospheric tracer dispersion experiments in terms of range, duration and objectives, and tracers used. Concluding remarks relating to the future use of these species are also presented. Copyright © 2011 Royal Meteorological Society
A visual representation for RNA secondary structure and its application
Authors: Liang C. , Luo J. W. , Li R. F. , Tu N. H.
Published: August 2011

The graphical representation of biological sequences is an important subject in the area of genome studies. We propose a novel visual representation for RNA secondary structures. Some symmetric properties and information on the base distribution and compositions can be intuitively reflected by the projection graphs of the points corresponding to the RNA secondary structures. Then our method is applied to compute the similarity of 12 classical samples and 11 real RNA secondary structures. The results indicate that our method can not only effectively analyze the similarity between RNA secondary structures but also show a high consistency with other literatures. Moreover, our method only needs the geometrical center of the characteristic curve of the RNA secondary structure to compute the similarity matrix, which means a low computational complexity. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
NH and NCl homolytic bond dissociation energies and radical stabilization energies: An assessment of theoretical procedures through comparison with benchmark‐quality W2w data
Authors: O'reilly Robert J. , Karton Amir , Radom Leo
Published: August 2011

The performance of a large variety of contemporary density functional theory (DFT), double‐hybrid DFT, and high‐level Gaussian‐n (Gn) procedures has been evaluated for the calculation of bond dissociation energies (BDEs) and radical stabilization energies (RSEs) associated with NX bonds (X = H, Cl). The chosen set of 62 NX systems (31 NH and 31 NCl) span a wide range of biologically relevant species. As reference values, we used benchmark‐quality W2w data that we recently obtained as part of a systematic thermochemical study of substituent effects in these systems. Of the Gn schemes, the modified G4 procedures (G4‐5H and G4(MP2)‐6X) perform somewhat better than the corresponding standard G4 procedures for the NX BDEs of these systems. For the NH RSEs, G3X, G3X(MP2), G3X(MP2)‐RAD, G4‐5H, and G4(MP2)‐6X emerge as excellent performers, with mean absolute deviations (MADs) from the benchmark W2w values of 0.9–1.4 kJ mol–1. However, for the NCl RSEs, G4 is the best performer, with an MAD of 1.7 kJ mol–1. The BDEs of both NH and NCl bonds represent a challenge for DFT procedures. In particular, only a handful of functionals (namely, B3P86, M05‐2X, M06‐2X, and ROB2‐PLYP) perform well, with MADs ≤ 4.5 kJ mol−1 for both bond types. Nearly all of the considered DFT procedures perform significantly better for the computation of RSEs, due to a significantly larger degree of error cancelation compared with the BDEs. For the RSEs, BH&HLYP, M05‐2X, M06, M06‐2X, BMK, PBE0, B2‐PLYP, B2GP‐PLYP, B2T‐PLYP, and ROB2‐PLYP are the best performers, with MADs ≤ 4.2 kJ mol−1. Reliable values of NH and NCl BDEs may be obtained by using the RSEs calculated by these functionals in conjunction with a thermochemical cycle involving an experimental (or high‐level theoretical) BDE for the H2NH or H2NCl bond. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
The host interactome of influenza virus presents new potential targets for antiviral drugs
Authors: Shaw Megan L.
Published: August 2011

Increasing antiviral drug resistance is a major concern for treating influenza, especially in a pandemic setting when the availability of a protective vaccine is uncertain. Resistance is often an issue with drugs directed at viral proteins and for small RNA viruses; there are also a limited number of viral proteins that are amenable to inhibition by a small molecule. A new approach that is gaining support is that cellular proteins, which facilitate virus replication, may be used as alternative targets. Whereas drugs directed at viral proteins tend to be virus‐specific, drugs directed at host targets have the potential to have broad‐spectrum antiviral activity as many viruses may share a dependency on that host function. For influenza virus, we have very limited knowledge of which cellular factors are involved in virus replication, let alone which of these have suitable properties to serve as drug targets. Through the use of high‐throughput RNA interference screens, several studies have addressed this gap in our knowledge. The resulting datasets provide new insight into host pathways that are involved in the influenza virus replication cycle and identify specific host factors in these pathways that may serve as potential targets for future antiviral drug development. Copyright © 2011 John Wiley & Sons, Ltd.