bluuebunny/crossref_metadata_2025 huggingface dataset:
Theoretical first step towards an understanding of the uranyl ion sorption on the rutile TiO2(110) face: A DFT periodic and cluster study
Authors: Perron H. , Domain C. , Roques Jerome , Drot R. , Simoni E. , Catalette H.
Published: November 2006

First results of a periodic and cluster Density Functional Theory (DFT) study of the uranyl ion (UO2
2+) sorption onto the rutile TiO2(110) face, based on plane wave and localised basis sets, are presented. A five layers slab with its most internal layer frozen to bulk positions was found to be a good surface model. In a first step and as reference data for the sorption process, the [UO2(H2O)n]2+ systems, with n=4 to 6 were studied. Relative solvation energies confirmed that the uranyl ion adopt a pentacoordinated structure in aqueous solution. From localised approach, an overall 0.91 electron transfer from the first hydration shell to the uranyl ion was calculated. Then, a periodic study of the uranyl sorption on a simplified hydroxylated TiO2(110) surface model was investigated. The resulting optimised structural parameters, for the three possible adsorption sites, show that the sorbed uranyl ion first coordination shell (saturated by three water molecules) plays an important role to model the adsorption process. Both methodologies (plane waves and localised atomic orbitals) were also used with a cluster model and gave similar results in agreement with experimental data. This first step in the understanding of the uranyl ion sorption onto the simplified hydroxylated TiO2(110) surface shows that hydrogen bonds should be included in the model in order to perform a more accurate description of the uranyl ion sorption process. A study with this surface model is currently performed in order to calculate the relative stabilities between the different uranyl adsorption sites and to compare with the experimental data.
Sorption of Cs, Ni, Pb, Eu(III), Am(III), Cm, Ac(III), Tc(IV), Th, Zr, and U(IV) on MX 80 bentonite: An experimental approach to assess model uncertainty
Authors: Grambow Bernd , Fattahi Massoud , Montavon Gilles , Moisan C. , Giffaut E.
Published: November 2006

A multi-site surface complexation/ion exchange model for dispersed MX 80 bentonite has been calibrated, considering the dissolution properties of the constituting mineral assemblage, for sorption of a large number of radionuclides, using experimental data from the present study together with well constrained literature data. Emphasis was on tri- and tetravalents actinides and fission products and reducing groundwater compositions.
The uptake of radium by calcium silicate hydrates and hardened cement paste
Authors: Tits Jan , Iijima Kazuki , Wieland Erich , Kamei Gento
Published: November 2006

In the present study the interaction of Ra(II) with calcium silicate hydrates (C-S-H) as well as with fresh and degraded hardened cement pastes (HCP) has been investigated using batch-type sorption tests. Synthetic C-S-H phases with varying CaO:SiO2 (C:S)mol ratios, relevant to non-degraded HCP and degraded HCP, were prepared in the absence of alkalis (Na(I), K(I)) and in an alkali-rich artificial cement pore water (ACW). The Ra(II) sorption kinetics, the effect of the solid to liquid ratio and the C:S mol ratio on the Ra(II) uptake were investigated. In addition, the reversibility of Ra(II) sorption was tested using dilution tests. Comparison with data on the uptake of Sr(II) by C-S-H phases obtained from previous in-house studies showed that the same model concept could be applied to interpret the immobilization of Sr(II) and Ra(II) in these systems. Ra(II) sorption on C-S-H in the absence of alkalis could be interpreted in terms of a Ra2+-Ca2+ cation exchange model. The Ra2+-Ca2+ exchange selectivity coefficient, Ra
CaKC, was determined to be (6±4). There are indications that, in the presence of alkalis, the Ra(II) sorption by C-S-H phases can only be described with the help of an ion-exchange model involving Ra2+, Ca2+ and the monovalent alkalis.

The cation exchange model developed for C-S-H phases in the absence of alkalis was successfully applied to predict the sorption of Ra(II) on degraded HCP, assuming that the Ra(II) sorbs solely on the C-S-H fraction of the HCP. Model predictions and experimental data were found to agree well in view of the simplified sorption model used.
Comparative study of cesium sorption on crushed and intact sedimentary rock
Authors: Xia Xiaobin , Iijima Kazuki , Kamei Gento , Shibata M.
Published: November 2006

For establishing a reliable safety assessment methodology for high-level radioactive waste (HLW) geological disposal, it is essential to clarify the applicability of sorption data determined with a conventional batch sorption method to an actual repository environment. In the present study, sorption data represented as distribution coefficients (K
d) were compared experimentally by applying a batch method with crushed sedimentary rock samples and a dynamic circulation method with intact sedimentary rock samples. The K
d values for cesium (Cs) determined with the dynamic circulation method are around one order of magnitude lower than those obtained using the batch method, depending on Cs concentration at sorption equilibrium. This disagreement was discussed considering permeability, specific surface area, solid/liquid ratio (S/L) and solution chemistry. The K
d values determined with the dynamic circulation method were corrected for different specific surface areas. As a consequence, the K
d values determined with the two methods are then comparable within an order of magnitude. The K
d values become even more comparable when taking into account that they decrease with increasing the S/L ratio as it is the case when going from batch to column experiments. The results basically suggest that the K
d determined with the batch method are reasonably applicable to describe sorption in the actual environment in a given nuclear waste repository after appropriate corrections.
Evaluation of the reversibility of iodide uptake by argillaceous rocks by the radial diffusion method
Authors: Savoye S. , Michelot J.-L. , Wittebroodt C.
Published: November 2006

Laboratory radial in- and out-diffusion experiments were performed to investigate the reversibility of the iodide (I-) uptake by argillaceous rocks from the Tournemire site (France). At first, the suitability of the method was demonstrated by means of deuterium depleted water (DDW) diffusion experiments. The values for the DDW effective diffusion coefficient (1.7 to 2.7×10-11m2s-1) are indeed very close to those obtained from previous through-diffusion experiments carried out on Tournemire samples with tritiated water. The diffusion of chloride and bromide led to the determination of halide-accessible porosities, which are necessary to calculate the retardation factor (R) and the distribution ratio (RD). The calculated values for the halide-accessible porosity (2 to 5%) clearly indicated the effect of anionic exclusion and are consistent with previous data. On the contrary, the in-diffusion experiments performed with iodide clearly showed its uptake by argillite, with rock capacity factor values ranging from 14% to 25%. The corresponding values ofRD(0.035 to 0.08 L kg-1) are one order of magnitude lower than those previously derived from batch methods. At last, the experiments of iodide out-diffusion revealed that only iodide located in the halide-accessible porosity diffused out of the rock samples, suggesting that the uptake of iodide by argillite would not be reversible or that the kinetics of desorption would be low (>70 days).
Thermal diffusion of chlorine in uranium dioxide
Authors: Pipon Y. , Toulhoat N. , Moncoffre N. , Jaffrézic H. , Gavarini S. , Martin P. , Raimbault L. , Scheidegger A. M.
Published: November 2006

In a nuclear reactor, isotopes such as 35Cl present as impurities in the nuclear fuel are activated by thermal neutron capture. During interim storage or geological disposal of nuclear fuel, the activation products such as 36Cl may be released from the fuel to the geo/biosphere and contribute to the “instant release fraction” as they are likely to migrate in defects and grain boundaries. In order to differentiate diffusion mechanisms due to “athermal” processes during irradiation from thermally activated diffusion, both irradiation and thermal effects must be assessed.

This work concerns the measurement of the thermal diffusion coefficient of chlorine in UO2.37Cl was implanted at a 1013 at/cm2 fluence in depleted UO2 samples which were then annealed in the 900−1200 °C temperature range and finally analyzed by Secondary Ion Mass Spectrometry (SIMS) to obtain 37Cl depth profiles. The migration process appears to be rather complex, involving mechanisms such as atomic, grain boundary, directed diffusion along preferential patterns as well as trapping into sinks before successive effusion. However, using a diffusion model based on general equation of transport, apparent diffusion coefficients could be calculated for 1000 and 1100 °C and a mean activation energy of 4.3 eV is proposed. This value is one of the lowest values compared to those found in literature for other radionuclides pointing out a great ability of chlorine to migrate in UO2 at relatively low temperatures.

In order to unequivocally determine the diffusion behaviour of both implanted and pristine chlorine before and after thermal annealing, the structural environment of chlorine in UO2 was examined using micro X-ray fluorescence (micro-XRF) and micro X-ray absorption spectroscopy (micro-XAS).
Rhenium migration at the Maqarin natural analogue site (Jordan)
Authors: Trotignon Laurent , Rose J. , Khoury H. , Milodowski A. , Bienvenu P. , Provitina O. , Mercier F. , Susini J.
Published: November 2006

Rock analysis and study of groundwater data was combined with a short duration column experiment in order to better understand the behavior of rhenium (Re) in the site of Maqarin (Jordan). Results show that the combustion metamorphism having affected rock masses in Maqarin (Jordan), and led to the formation of “natural cements”, has strongly modified the spatial distribution of several elements, among which Re, creating a specific source term for this element leached by groundwaters. Unaltered cements are shown to contain up to 1.2 μg/g Re to be compared to 0.15 μg/g in the initial biomicrite. Re is rapidly leached from unaltered cements and can be used as a tracer of recent cement alteration episodes. Preliminary data suggest that Re, a chemical analogue of Tc, could be partially retained in fracture minerals.
Comparison of Native and Introduced Flathead Catfish Populations in Alabama and Georgia: Growth, Mortality, and Management
Authors: Sakaris Peter C. , Irwin Elise R. , Jolley Jeffrey C. , Harrison Donald
Published: November 2006

We compared growth of flathead catfish Pylodictis olivaris from two native populations in Alabama (Coosa and Tallapoosa rivers) and two introduced populations in Georgia (Ocmulgee and Satilla rivers). We also compared mortality rates and potential outcomes of various management regimes (minimum length limits [MLLs]) among the populations. Total length–log10(age) regression slopes for introduced fish were higher than those for native fish, and von Bertalanffy growth coefficients (K) were greater for introduced fish (Ocmulgee: 0.195; Satilla: 0.201) than for native individuals (Coosa: 0.057; Tallapoosa: 0.059). Therefore, introduced flathead catfish grew more rapidly than those in their native range. Mortality (instantaneous mortality rate, Z) was higher in the Satilla River population (Z = −0.602) than in the Ocmulgee River (Z = −0.227) and Coosa River (Z = −0.156) populations. However, fish in the Satilla River population had been introduced for only 10 years and presumably did not reach their theoretical maximum age, potentially biasing the mortality estimate for that population. Simulation of management regimes in Fishery Analyses and Simulation Tools software predicted that maximum biomass of flathead catfish in the Ocmulgee (1,668 kg) and Satilla (1,137 kg) rivers was substantially larger than that in the Coosa (873 kg) and Tallapoosa (768 kg) populations. However, increased exploitation rates in the Ocmulgee and Satilla River populations resulted in dramatic declines in overall biomass, especially at lower MLLs (254 and 356 mm, respectively). Therefore, in systems where introduced flathead catfish represent an important recreational fishery but have dramatically reduced the abundance of native fishes through predation, minimal protection is recommended. We contend that rapid growth of introduced flathead catfish has major implications for their management and the conservation of native fishes.
Modular Experimental Riffle–Pool Stream System
Authors: Matthews William J. , Gido Keith B. , Garrett Gary P. , Gelwick Frances P. , Stewart Jeffrey G. , Schaefer Jacob
Published: November 2006

We describe a modular method for building a large, outdoor experimental stream system that has great flexibility for research projects in fish ecology, behavior, conservation, or management. The system has been in use for more than a decade at the University of Oklahoma Biological Station (Kingston, Oklahoma) and has been used with modification at four other research facilities in the Midwest. Here, we document the system in detail, including specifications for construction of the original system and modifications or improvements at other sites. The system uses commercially available, customized fiberglass round tank and trough units that can be configured in many different ways to create flowing pool and riffle habitats. The system appears to be a good mimic of small natural streams based on system flow rates, establishment of natural substrates and cover, stream chemistry relative to that of a natural creek, and fish behaviors. At least 39 fish species have been used successfully in 1–14‐month experiments in these systems and approximately half have reproduced. The system offers great flexibility of design to experimenters, is cost effective, and may be of interest at other facilities that research basic biology, conservation, or management of stream fishes.
Potential evapotranspiration estimates for northeast Brazil using GOES-8 data
Authors: Bastos Eduardo J. de Brito , Souza Jaidete M. de , Rao Tantravahi V. Ramana
Published: November 2006

In this study, an empirical method proposed by Caselles et al. (1992a) is utilized to determine the potential evapotranspiration (ETP) on a regional scale. This method uses the global solar radiation data retrieved by the global radiation model GL1.0, which in turn utilizes data from the visible channel of the GOES-8 satellite. This method is applied to the northeast region of Brazil, using daily and monthly climatological data as the ground truth information to estimate the ETP and the estimated daily ETP data for September, 1997. The methodology involved three steps: 1) to perform a spatial regionalization of the ETP using the method of Ward, which is available in the Statistical Package for the Social Sciences (SPSS); 2) to obtain the correlation between the ETP as estimated by the methods of Jensen & Haise (1963) - MJH, Caselles (1992a) - MCA, and the Penman's combined method (1948) - MCP; 3) to test the sensibility of the empirical formulations proposed and to assess the estimates using the satellite-based global solar radiation provided by the GL1.0 model. The spatial regionalization shows two distinct regions in the Northeastern Brazil. The MCA yielded better results than the MJH. The ETP estimates using satellite data were satisfactory, showing a maximum error of 20% when compared with the ground truth data.
Shear and normal interaction stresses via strain–moment plots
Authors: Sebastian W. M.
Published: November 2006

The present paper focuses on prediction of FRP-to-steel longitudinal shear stresses in yield zones of loaded steel beams with bonded fibre reinforced polymer (FRP) strips. Application of multi-variable differential calculus reveals that two physically meaningful quantities permit considerable insight into the longitudinal variations of these shear stresses. One of these quantities—the rate of change of FRP strain with total section moment—is a characteristic of the FRP-steel hybrid section, and is of course readily obtained from the plot of FRP strain versus section moment. The other quantity, the shear force, represents the effect of the applied load along the member. The merits of this approach to longitudinal shear prediction are compared with those of an alternative method developed previously. Illustrative numerical examples are provided. It is then shown that the accompanying FRP-to-steel normal stress is here influenced mainly by the rate of change along the member of the longitudinal shear stress. This fact in turn leads to striking differences between normal stresses obtained from rigid bond analyses and those obtained via bond-slip analyses. Hence it is shown that while rigid bond analysis may be preferred for reduced complexity and greater time efficiency, such analysis may lead to erroneous conclusions on proximity to bond failure in yield zones. Finally, an efficient method for establishing the maximum height of tension yield in the steel web near the FRP strip is presented, and the importance of this height to buckling-restraint of the web is discussed.
Defining the roles of Ca2+ — permeable channels in sperm
Authors: Sadiqul Islam M.
Published: November 2006

Ion channels exert a vital role in the dialogue between male and female gametes and thus in the generation of new individuals in many species. Intracellular Ca2+ is possibly the key messenger between gametes. Different Ca2+-permeable channels have been detected in the plasma membrane and in the organelle-like acrosome membrane of sperm, which play vital roles in determining sperm fertilizing ability. Recent reports from several laboratories have adequately documented that the Ca2+-permeable channels of a sperm control a variety of functions ranging from motility to the acrosome reaction. In this article, we have reviewed the data from our and other laboratories, and have documented the mechanisms of different Ca2+-permeable channels involved in the fertilization event.
Evaluation of the burden of logging injuries using West Virginia workers' compensation claims data from 1996 to 2001
Authors: Mujuru Priscah , Singla Lisa , Helmkamp James , Bell Jennifer , Hu Wen
Published: November 2006

Background

The risks associated with logging are well documented, however little work has been done on estimating the economic impact of injuries among loggers.

Methods

West Virginia Workers' Compensation claims data for the period 1996–2001 was used to assess the economic burden of logging injuries in the state.

Results

There were 1,371 claimants during this period with the highest number of claims (39%) in the 25–34 years age category. The total cost of injuries was over $14 million. The most severe injuries, traumatic brain injuries (TBI), thoracic, cervical, and lumbar, resulted in the highest medical costs, indemnity costs and permanent disability. The average medical cost for logging‐related to TBI was $198,048 compared to $15,321 for other major industries.

Conclusions

The magnitude of the economic costs underscores the need for active research of injury prevention among loggers and for greater attention to occupational safety and health programs. Am. J. Ind. Med. 2006. © 2006 Wiley‐Liss, Inc.
Validity of the Center for Epidemiologic Studies Depression Scale as a screening instrument of major depressive disorder among Japanese workers
Authors: Wada Koji , Tanaka Katsutoshi , Theriault Gilles , Satoh Toshihiko , Mimura Masaru , Miyaoka Hitoshi , Aizawa Yoshiharu
Published: November 2006

Background

The Center for Epidemiologic Studies Depression Scale (CES‐D) is used at workplaces to screen depressive disorders. The aim of this study was to examine the validity of the CES‐D for depression in a workplace.

Methods

The CES‐D was administered to 2,219 workers (84.2% men; age 21–68 years) at a manufacturing company in Japan. Concomitantly all workers had an interview with the Mini International Neuropsychiatric Interview (MINI) as a gold standard for diagnosing major depressive disorder (MDD). The validity was evaluated by a receiver operating characteristic (ROC) curve.

Results

The area under the ROC curve of the CES‐D was 0.96 [95% Confidence Interval (CI): 0.94–0.99]. The optimal cut‐off score of MDD was 19 for screening.

Conclusions

The validity of CES‐D is confirmed and it is a valid instrument for detecting MDD in working populations in Japan. Am. J. Ind. Med. 50:8–12, 2007. © 2006 Wiley‐Liss, Inc.
Risk for hypertension in workers exposed to carbon disulfide in the viscose rayon industry
Authors: Chang Shu‐Ju , Chen Chiou‐Jong , Shih Tung‐Sheng , Chou Tzu‐Chieh , Sung Fung‐Chang
Published: November 2006

Background

Chronic exposure to carbon disulfide (CS2) has been associated with hypertension, elevated cholesterol, arteriosclerosis, ischemic heart disease and related mortality, adverse nervous and reproductive health effects, and hearing impairment. This study assessed the hypertension risk for male rayon workers exposed to CS2.

Methods

A total of 251 rayon workers and 226 administrative clerks at two plants in Taiwan received health examination and interviews, and were compared for hypertension risk. On‐site CS2 levels were measured.

Results

The hypertension was more prevalent in the exposure group (43.4%) than in controls (7.1%) with greater impact on systolic blood pressure than diastolic. Multivariate logistic regression analysis showed a significant dose–response relationship between hypertensive risk and cumulative exposure index (CEI) with an odds ratio of 15.1 for workers exposed to 343–468 year‐ppm of CS2. The overall risk was elevated to 7.6 times higher for rayon workers. The risk increased significantly after more than 10 years of employment.

Conclusions

This study suggests that it takes a long exposure period to develop hypertension for rayon workers with CS2 exposure. Am. J. Ind. Med. 50:22–27, 2007. © 2006 Wiley‐Liss, Inc.
An unusual cause of atrial fibrillation: Exposure to insecticides
Authors: Topacoglu Hakan , Unverir Pinar , Erbil Bulent , Sarikaya Sezgin
Published: November 2006

Background

Although there are many well‐known cardiac results of insecticide poisoning, atrial fibrillation (AF) has not been reported as the result of insecticide intoxication.

Case

Twenty‐six‐year‐old male, complaining of nausea and vomiting, presented to the emergency department with a history of methomyl dust exposure. All physical examination findings were normal except irregular heart rate on cardiac auscultation. The electrocardiogram of the patient showed AF with normal ventricular response. Patient's acetylcholinesterase (ACE) level was 3,319 IU/L in presentation and pralidoxim use was seen unnecessary for the treatment. The patient's rhythm spontaneously returned to sinus rhythm 24 hr after the presentation and no cardiopulmonary pathology was found during the follow‐up. The patient was discharged without symptoms.

Conclusion

AF is a rare complication of insecticide intoxication. In this case, treatment of symptoms was adequate until a normal sinus rhythm returned. Am. J. Ind. Med. 50:48–49, 2007. © 2006 Wiley‐Liss, Inc.
GLI2 mutations in four Brazilian patients: How wide is the phenotypic spectrum?
Authors: Rahimov Fedik , Ribeiro Lucilene Arilho , de Miranda Eziquiel , Richieri‐Costa Antonio , Murray Jeffrey C.
Published: November 2006

We report four patients with GLI2 mutations together with their associated phenotypes: (1) holoprosencephaly‐like phenotype, (2) anophthalmia, branchial arch anomalies, and CNS abnormalities, (3) heminasal aplasia and orbital anomalies, and (4) lobar holoprosencephaly. This diversity of phenotypes expands our understanding. Findings include not only (1) holoprosencephaly or a holoprosencephaly‐like phenotype, but also (2) heminasal aplasia with orbital anomalies, and (3) branchial arch anomalies of the type seen in hemifacial microsomia with anophthalmia and in oculoauriculofrontonasal syndrome. Finally, this is the first report of a double mutation involving GLI2 and PTCH in the same patient. © 2006 Wiley‐Liss, Inc.
Improvement in processability of metallocene polyethylene by ultrasound and binary processing aid
Authors: Chen Jinyao , Liu Xiaolong , Li Huilin
Published: November 2006

The effect of ultrasonic vibration and binary processing aid in improving the processability of metallocene linear low‐density polyethylene (mLLDPE) was investigated. During extrusion, ultrasonic vibration clearly reduced the die pressure and apparent viscosity of mLLDPE but had only a slight effect on its melt fracture. The effect of diatomite/PEG binary processing aid (BPA) was excellent in reducing the viscosity and eliminating the sharkskin fracture of mLLDPE. The effect of ultrasonic vibration and binary processing aid in improving the processability of mLLDPE was synergetic. With a combination of ultrasonic vibration and a small amount of processing aid, the flowability of mLLDPE was further improved, and the critical shear rate for the onset of sharkskin fracture was increased. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1927–1935, 2007
Comparative study on the preparation and properties of radiation‐grafted polymer electrolyte membranes based on fluoropolymer films
Authors: Chen Jinhua , Septiani Upita , Asano Masaharu , Maekawa Yasunari , Kubota Hitoshi , Yoshida Masaru
Published: November 2006

In this study the fluoropolymers, poly(ethylene‐co‐tetrafluoroethylene) (ETFE) and poly(vinylidene fluoride) (PVDF) films, together with the radiation‐induced crosslinked polytetrafluoroethylene (cPTFE) film were compared on the basis of their preparation and properties of radiation‐grafted polymer electrolyte membranes. The polymer electrolyte membranes were prepared by radiation grafting of styrene into the base films and subsequent sulfonation. The proton conductivity and chemical stability of the three types of membranes with a similar ion exchange capacity (IEC) near 1.0 mmol/g were investigated and are discussed in detail. Although the ETFE‐based polymer electrolyte membrane was relatively more stable, its proton conductivity was lower than those of the PVDF‐ and cPTFE‐based membranes. On the other hand, the cPTFE‐based membrane showed a significantly higher proton conductivity, but its chemical stability was shorter than that of the ETFE‐based membrane. It is considered that the difference in the preparation and properties of the polymer electrolyte membranes was due to the difference in the degree of crystallinity as well as in the chemical structure of the fluoropolymer base films. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1966–1972, 2007
Dielectric and thermal properties of polymer network based on bismaleimide resin and cyanate ester containing dicyclopentadiene or dipentene. III
Authors: Hwang Hann‐Jang , Shieh Jeng‐Yueh , Li Chun‐Hung , Wang Chun‐Shan
Published: November 2006

A series of bismaleimide‐triazine (BT) resins were prepared from commercial bismaleimide (DDMBMI) and 2,6‐dimethylphenol‐dicyclopentadiene dicyanate ester (DCPDCY) or 2,6‐dimethylphenol‐dipentene dicyanate ester (DPCY). The thermal properties of cured BT resins containing DCPD or DP were studied using a dielectric analyzer (DEA), dynamic mechanical analyzer (DMA), and thermal gravimetric analyzer (TGA). These data were compared with that of DDMBMI cured with bisphenol A dicyanate ester (BADCY). The cured DDMBMI/DCPDCY or DDMBMI/DPCY exhibits a lower dielectric constant, dissipation factor, and moisture absorption than those of DDMBMI/BADCY. The effects of blend composition on the glass transition temperatures and thermal stability are discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1942–1951, 2007
Thermal oxidative degradation kinetics of PP and PP/mg (OH)2 flame‐retardant composites
Authors: Chen Xiaolang , Yu Jie , Guo Shaoyun
Published: November 2006

The thermal stability and thermal oxidative degradation kinetics of polypropylene (PP) and flame‐retardant PP composites filled with untreated and treated magnesium hydroxide (MH) in air were studied by thermogravimetric analysis (TGA). The effect of the heating rate in dynamic measurements (5°C–30°C/min) on kinetic parameters such as activation energy was also investigated. The Kissinger and Flynn–Wall–Ozawa methods were used to determine the apparent activation energy for the degradation of neat PP and flame‐retardant PP composites. The results of TGA showed that the addition of untreated or treated MH improved the thermal oxidative stability of PP in air. The kinetic results showed that the apparent activation energy for degradation of flame‐retardant PP composites was much higher than that of neat PP, suggesting that the flame retardant used in this work had a great effect on the mechanisms of pyrolysis and combustion of PP. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1978–1984, 2007
Blend membranes of chitosan and poly(vinyl alcohol) in pervaporation dehydration of isopropanol and tetrahydrofuran
Authors: Rao K. S. V. Krishna , Subha M. C. S. , Sairam M. , Mallikarjuna N. N. , Aminabhavi T. M.
Published: November 2006

Blend membranes of a natural polymer, chitosan, with a synthetic polymer, poly(vinyl alcohol) (PVA), were prepared by solution casting and crosslinked with a urea formaldehyde/sulfuric acid (UFS) mixture. Chitosan was used as the base component in the blend system, whereas PVA concentration was varied from 20 to 60 wt %. Blend compatibility was studied by differential scanning calorimetry, and Fourier transform infrared spectroscopy was used to study membrane crosslinking. Membranes were tested for pervaporation dehydration of isopropanol and tetrahydrofuran (THF) at 30°C in close proximity to their azeotropic compositions. Membrane performance was assessed by calculating flux and selectivity. Swelling experiments performed in water + organic mixtures at 30°C were used to explain the pervaporation results. The blend membrane containing 20 wt % PVA when tested for 5 and 10 wt % water–containing THF and isopropanol feeds exhibited selectivity of 4203 and 17,991, respectively. Flux increased with increasing concentration of water in the feed. Selectivity was highest for the 20 wt % PVA‐containing blend membrane. The results of this study are unique in the sense that the crosslinking agent used—the UFS mixture—was novel. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1918–1926, 2007
Ink and moisture sorption study in UV‐curable polyurethane acrylate
Authors: Tey J. N. , Soutar A. M. , Priyadarshi A. , Mhaisalkar S. G. , Hew K. M.
Published: November 2006

A study of the interaction of commercial black ink with a UV‐curable polyurethane acrylate (PUA) is presented. Diffusivity and solubility in PUA cured using different UV dosages, and subjected to different post‐UV curing conditions, were studied, as was the swelling produced by such sorption. Experiments were also conducted using water, to serve as a benchmark and compare with the effect of ink. The percentage ink absorption was found to decrease with higher degree of cure. In addition, through desorption measurements, ink induced swelling of PUA processed under different conditions was determined. The degree of swelling per unit solvent uptake was observed to increase with the degree of cure. PUA was determined to be more prone to moisture rather than solvent uptake. However, the coefficient of moisture expansion (CME) was found to be ∼ 35% lower than the coefficient of ink expansion (CIE) for a fully cured PUA. © 2006 Wiley Periodicals, Inc. JAppl PolymSci 103: 1985–1991, 2007
In vitro degradation of dry‐jet‐wet spun poly(lactic acid) monofilament and knitted scaffold
Authors: Gupta Bhuvanesh , Revagade Nilesh , Hilborn Jöns
Published: November 2006

In vitro degradation behavior of dry‐jet‐wet spun poly(lactic acid) (PLA) monofilament and knitted scaffold were studied at three different pH i.e., at 4.6, 7.4, and 8.0 at 37°C for 20 weeks. Characterization of PLA by intrinsic viscosity, thermal properties, and scanning electron microscopy (SEM) was carried out. It is observed that the pH of the medium has significant role on degradation behavior of PLA. The degradation at pH 4.6 is observed to be maximum, which is confirmed by the drop of 52% in intrinsic viscosity. The degradation process has effect on the hydrophobicity of the PLA. The decrease in contact angle from 73° to 48° indicates that the PLA surface tends to become more hydrophilic as the degradation proceeds. The SEM analysis showed that with the degradation, surface deterioration takes place. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2006–2012, 2007
Enzymatic degradation of poly(L‐lactic acid) fibers: Effects of small drawing
Authors: Tsuji Hideto , Kidokoro Yuki , Mochizuki Masatsugu
Published: November 2006

The enzymatic degradation of poly(L‐lactic acid) (PLLA) fibers with different low draw ratios (1.0, 1.2, and 1.4 times) was investigated in tris‐HCl buffer solution (pH = 8.6) with proteinase K by the use of gravimetry, scanning electron microscopy (SEM), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and tensile testing. Surprisingly, even the small drawings (1.2 and 1.4 times) disturbed the proteinase K catalyzed enzymatic degradation of the PLLA fibers. This should have been because the enzyme could not attach to the extended (strained) chains in the amorphous regions of the uniaxially oriented PLLA fibers or could not catalyze the cleavage of the strained chains. The accumulation of crystalline residues formed as a result of selective cleavage, and removal of the amorphous chains was not observed, even for as‐spun PLLA fibers. This indicated the facile release of formed crystalline residues from the surface of the as‐spun PLLA fibers during enzymatic degradation. Such release may have been because the crystalline regions of the as‐spun PLLA fibers were oriented with their c axis parallel to the machine direction, as reported for biaxially oriented PLLA films. Gravimetry, SEM, and tensile testing could trace the enzymatic degradation of the PLLA fibers, although the enzymatic degradation of the PLLA fibers was untraceable by GPC and DSC. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2064–2071, 2007
Ionic elastomers based on carboxylated nitrile rubber and magnesium oxide
Authors: Ibarra L. , Alzorriz M.
Published: November 2006

The crosslinking of carboxylated nitrile rubber (XNBR) with magnesium oxide (MgO) leads to an ionic elastomer with thermoplastic nature and better physical properties than the ones obtained with other metallic oxides. The crosslinking reaction leads to the formation of a metallic salt as unique product, as it could be seen on the ATR analysis of the samples, prepared at different reaction times. The mechanical properties of the material increase with the amount of crosslinking agent and segregation of an ionic microphase takes place. The presence of this microphase is demonstrated by a relaxation at high temperatures. The apparent activation energy of this relaxation is smaller than the activation energy of the glass transition of the elastomer, the former being more dependent on the amount of metallic oxide than is the latter. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1894–1899, 2007
Understanding journal usage: A statistical analysis of citation and use
Authors: McDonald John D.
Published: November 2006

This study examined the relationship between print journal use, online journal use, and online journal discovery tools with local journal citations. Local use measures were collected from 1997 to 2004, and negative binomial regression models were designed to test the effect that local use, online availability, and access enhancements have on citation behaviors of academic research authors. Models are proposed and tested to determine whether multiple locally recorded usage measures can predict citations and if locally controlled access enhancements influence citation. The regression results indicated that print journal use was a significant predictor of local journal citations prior to the adoption of online journals. Publisher‐provided and locally recorded online journal use measures were also significant predictors of local citations. Online availability of a journal was found to significantly increase local citations, and, for some disciplines, a new access tool like an OpenURL resolver significantly impacts citations and publisher‐provided journal usage measures.
The changing nature of information work in museums
Authors: Marty Paul F.
Published: November 2006

This article presents results from 21 semi‐structured interviews with museum information professionals (MIPs) who were asked about their experiences working with information resources, tools, and technologies. Interviews were analyzed to determine (a) the challenges MIPs face as they adapt to changing technical capabilities and strive to meet the changing needs and expectations of museum users and (b) the coping mechanisms MIPs employ on the job that enable them to deal effectively with those challenges. This article explores the results of this analysis, exploring how MIPs cope with the changing nature of information work in museums by relying on thirteen different strategies including (a) assessing new technologies in relation to the museum's core mission, (b) helping museum professionals embrace new ideas about information access and provision, and (c) promoting internal practices that encourage the sharing of information and the integration of information science into museum work. This article also discusses the implications of these challenges and strategies for current and future MIPs, and assesses their impact on changing perceptions, roles, and research for information professionals in museums as they work to meet the information needs of all museum users.
Amine‐Templated One‐Dimensional Metal Sulfates Including a Mixed‐Valent Fe Compound with a Half‐Kagome Structure
Authors: Behera J. N. , Rao C. N. R.
Published: November 2006

Organically templated metal sulfates are relatively new. Six amine‐templated transition‐metal sulfates with different types of chain structures, including a novel iron sulfate with a chain structure corresponding to one half of the kagome structure, were synthesized by hydro/solvothermal methods. Amongst the one‐dimensional metal sulfates, [C10N2H10][Zn(SO4)Cl2] (1) is the simplest, being formed by corner‐linked ZnO2Cl2 and SO4 tetrahedra. [C6N2H18][Mn(SO4)2(H2O)2] (2) and [C2N2H10][Ni(SO4)2(H2O)2] (3) have ladder structures comprising four‐membered rings formed by SO4 tetrahedra and metal–oxygen octahedra, just as in the mineral kröhnkite. [C4N2H12][VIII(OH)(SO4)2]⋅H2O (4) and [C4N2H12][VF3(SO4)] (5) exhibit chain topologies of the minerals tancoite and butlerite, respectively. The structure of [C4N2H12][H3O][FeIIIFeII F6(SO4)] (6) is noteworthy in that it corresponds to half of the hexagonal kagome structure. It exhibits ferrimagnetic properties at low temperatures and the absence of frustration, unlike the mixed‐valent iron sulfate with the full kagome structure.
Randomized clinical trial of Lichtenstein's operation versus mesh plug for inguinal hernia repair
Authors: Frey D M , Wildisen A , Hamel C T , Zuber M , Oertli D , Metzger J
Published: November 2006

Background

Two of the most commonly used open prosthetic tension-free techniques for inguinal hernia repair are Lichtenstein's operation and the mesh plug repair. The technique of choice remains a subject of ongoing debate. The objective of the present investigation was to compare the two surgical procedures with respect to associated morbidity and recurrence rates.

Methods

Five hundred and ninety-five patients with 700 primary or recurrent inguinal hernias were randomized to undergo either Lichtenstein's operation or mesh plug repair. The primary endpoint of the investigation was the recurrence rate 1 year after surgery. Secondary endpoints were perioperative complications and reoperation rates.

Results

At 12-month follow-up, 597 hernia repairs (85·3 per cent) were evaluated. There were no significant differences regarding recurrence rates and perioperative complications. However, there was a significant difference in the overall reoperation rate between the two treatment groups, with 13 reoperations (4·2 per cent) in the Lichtenstein group and four (1·4 per cent) in the mesh plug group (P = 0·047).

Conclusion

Lichtenstein's operation and the mesh plug repair are comparable with respect to perioperative complications and recurrence rates.
Structure, Stability and Guest Affinity of Tris(3‐ureidobenzyl)amine Capsules in Solution
Authors: Alajarín Mateo , Pastor Aurelia , Orenes Raúl‐Angel , Martínez‐Viviente Eloísa , Rüegger Heinz , Pregosin Paul S.
Published: November 2006

In non‐competitive solvents, the tris(3‐ureidobenzyl)amines 1 a–c form dimeric assemblies in which guests such as CH3CN, CH3NO2, CH2Cl2, CH3I, CH2BrCl, CH2Br2, CHCl3 and C6H6 can be encapsulated. Variable temperature 1H and 1H,1H‐ROESY NMR spectroscopy, as well as pulsed‐gradient spin‐echo (PGSE) diffusion measurements were used to investigate the encapsulation within 1 a⋅1 a (1 a: tris{3‐[N′‐(4‐butylphenyl)ureido]benzyl}amine). Kinetic parameters for the encapsulation of CH3NO2, CH2Cl2 and CH3I, both in CDCl3 and in [D8]toluene have been obtained by using magnetisation transfer methods. These data are discussed together with the thermodynamic parameters. The affinity between guest and capsule seems to be dictated mainly by the electronic, size and shape complementarity between cavity and guest. A gating mechanism for guest exchange is proposed.
Effective HPLC resolution of [4]heterohelicenium dyes on chiral stationary phases using reversed‐phase eluents
Authors: Villani Claudio , Laleu Benoît , Mobian Pierre , Lacour Jérôme
Published: November 2006

[4]Heterohelicenium cations 1a–c adopt a twisted helical structure that renders them chiral. They are configurationally stable and their enantiomers have been resolved, for the first time, by HPLC on Chiralcel OD‐RH and Chirobiotic TAG chiral stationary phases (CSPs). Chiral cations 1a–c have been resolved by HPLC using water‐based eluents containing KPF6 as additive. The elution order of the analyte enantiomers was determined by on‐line CD detection, and was found to be opposite on the two CSPs. The effect of mobile phase composition and analyte structure on retention and enantioselectivity was investigated. Chirality 19:601–606, 2006 © 2006 Wiley‐Liss, Inc.
Investigation of the stability of Chiralpak AD chiral stationary phase under various solvent conditions and development of a method to identify stationary phase‐derived polymer contamination
Authors: Welch Christopher J. , Fairchild Jacob , Sajonz Peter
Published: November 2006

The stability of Chiralpak AD chiral stationary phase under various solvent conditions was investigated. An analytical method for the detection of the presence of solubilized Chiralpak AD coating was developed using CD spectroscopy (CD signal at 245 nm). In addition, NMR analysis of the solubilized polymer revealed a characteristic signal for the 3,5‐dimethylphenyl carbamate methyl protons at around 2.5 ppm. Both of these methods may be helpful in detecting contamination by the Chiralpak AD polymer or in the study of CSP solvent compatibility. Chirality 19:607–611, 2006 © 2006 Wiley‐Liss, Inc.
Spectroscopic rationalization of the separation abilities of decaproline chiral selector in dichloromethane–isopropanol solvent mixture
Authors: Zhang Peng , Polavarapu Prasad L. , Huang Junmin , Li Tingyu
Published: November 2006

A chiral column, with decaproline as the chiral selector, has broad chiral selectivity. To understand the separation mechanism of this chiral column, multiple spectroscopic techniques, including optical rotation, electronic circular dichroism, infrared absorption and vibrational circular dichroism, have been used here to study the conformation of the decaproline oligomer in isopropanol(IPA)/dichloromethane(DCM) mixtures. These studies indicate that decaproline oligomer adopts polyproline II conformation in IPA/DCM solvent system (0% IPA ∼ 100% IPA). Hydrogen bonding interactions between CO groups of decaproline and IPA molecules increase as the content of IPA in the solvent mixture increases up to 60% and become less significant from then onwards. These spectroscopic observations are found to have a good correlation with the enantiomeric separation of racemic 2,2,2‐trifluoro‐1‐[10‐(2,2,2‐trifluoro‐1‐hydroxy‐ethyl‐anthracen‐9‐yl]‐ethanol by the decaproline column. Chirality 2006. © 2006 Wiley‐Liss, Inc.
Sensitivity improvement of circular dichroism detection in HPLC by using a low‐pass electronic noise filter: Application to the enantiomeric determination purity of a basic drug
Authors: Lorin Marie , Delepee Raphael , Maurizot Jean‐Claude , Ribet Jean‐Paul , Morin Philippe
Published: November 2006

The quality control of chiral drugs requires the determination of their enantiomeric purity. Nowadays, circular dichroism (CD) spectroscopy is gaining increasing importance in pharmaceutical analysis because of the commercially available CD detector in liquid chromatography. The separation of the two enantiomers of a basic drug (efaroxan) was achieved by high performance liquid chromatography using an amylose‐derivated column with both UV and CD detections. A baseline‐resolved separation (resolution: 5) was obtained after optimization of the mobile phase composition with hexane‐ethanol‐diethylamine (90:10:0.05; v/v/v). The use of a commercial low‐pass electronic noise filter of the CD signal has improved the signal‐to‐noise ratio by a factor twelve and allowed the quantitation of each enantiomer in the 1.25–300 μg ml−1 concentration range. The CD linear calibration curve, expressed in terms of stereoisomer height ratio versus concentration ratio, was plotted over the 0.4–6% range. A correlation coefficient greater than 0.999 was obtained by least‐squares regression and the limit of detection for the distomer/eutomer ratio was estimated at 0.14%. Although the method validation showed good repeatability on the retention times (RSD < 0.9%), on the peak height ratios (RSD < 8.7%) of each enantiomer only up to 99.2% enantiomeric purity was achieved. Chirality, 2006. © 2006 Wiley‐Liss, Inc.