bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydrophilic zeolite coatings for improved heat transfer: A quantitative analysis
Authors: Liu Jie , Aguilar Guillermo , Munoz Ronnie , Yan Yushan
Published: January 2008

The wetting diameter and life time of a water droplet on the surface of a bare, ZSM‐5 coated, and Zeolite‐A coated stainless steel 304 substrate at different initial surface temperatures was experimentally studied. ZSM‐5 and Zeolite‐A coated SS‐304 are more much more hydrophilic than bare stainless steel 304 as reflected by their contact angles (27° and 0° vs. 90°). The ZSM‐5 and Zeolite‐A coatings significantly outperformed the bare SS‐304 by decreasing the droplet life time, increasing the heat flux and increasing the heat transfer coefficient at all initial surface temperatures studied. At the highest surface temperature studied, T0 = 200°C, ZSM‐5, and Zeolite‐A coatings are shown to increase the maximum heat flux on bare SS‐304 by as much as 106% and 72%, respectively. At this temperature, the maximum heat transfer coefficients on ZSM‐5 and Zeolite‐A coatings are improved by 470% and 530% over the bare SS‐304, respectively. © 2008 American Institute of Chemical Engineers AIChE J, 2008
Teaching undergraduate research
Authors: Henderson LaRhee , Buising Charisse , Wall Piper
Published: January 2008

Undergraduate research in the biochemistry, cell, and molecular biology program at Drake University uses apprenticeship, cooperative‐style learning, and peer mentoring in a cross‐disciplinary and cross‐community educational program. We call it the one‐room schoolhouse approach to teaching undergraduate research. This approach is cost effective, aids learning, supports the development of science and transferable management skills, is productive, and supports diversity. It allows a small set of faculty to involve large numbers of students in research and maintain a productive scholarship program. It provides students with skills in scientific research and transferable skills that they apply to a wide set of careers.
A birth‐to‐death view of mRNA from the RNA recognition motif perspective
Authors: Kinzy Terri Goss , De Stefano Lauren A. , Esposito Anthony M. , Hurley Jennifer M. , Roy Rohini , Valentin‐Acevedo Anibal J. , Chang Kai‐Hsiung , Davila Jonathan , Defren Jennifer M. , Donovan Jesse , Irizarry‐Barreto Patricia , Soto Anibal , Ysla Riza M. , Copeland H. Liesel , Copeland Paul R.
Published: January 2008

RNA binding proteins are a large and varied group of factors that are the driving force behind post‐transcriptional gene regulation. By analogy with transcription factors, RNA binding proteins bind to various regions of the mRNAs that they regulate, usually upstream or downstream from the coding region, and modulate one of the five major processes in mRNA metabolism: splicing, polyadenylation, export, translation and decay. The most abundant RNA binding protein domain is called the RNA Recognition Motif (RRM)1. It is probably safe to say that an RRM‐containing protein is making some contact with an mRNA throughout its existence. The transcriptional counterpart would likely be the histones, yet the multitude of specific functions that are results of RRM based interactions belies the universality of the motif. This complex and diverse application of a single protein motif was used as the basis to develop an advanced graduate level seminar course in RNA:protein interactions. The course, utilizing a learner‐centered empowerment model, was developed to dissect each step in RNA metabolism from the perspective of an RRM containing protein. This provided a framework to discuss the development of specificity for the RRM for each required process.
Child sexual abuse: from prevention to self‐protection
Authors: Kenny Maureen C. , Capri Vjolca , R. Reena , Thakkar‐Kolar  , Ryan Erika E. , Runyon Melissa K.
Published: January 2008

There are a growing number of child abuse prevention and education programmes, including primarily group‐based parent and child education, which are taught by teachers within the school system. This article reviews some of the existing sexual abuse education and/or body safety programmes, as well as the research surrounding them. Advantages as well as criticisms of such programmes are reviewed. Issues such as target populations (i.e. children, teachers, parents), programme components and methodological limitations are addressed. Major findings include: children as young as three can be effectively taught self‐protection skills, parental and family involvement in training is important, and repeated exposure helps children maintain knowledge gains. The components of successful programmes include teaching children to identify and resist inappropriate touching, reassuring children that it is not their fault and learning the proper names of their genitals. Finally, future directions for programme development, research and policy are explored. Copyright © 2008 John Wiley & Sons, Ltd.
Electrochemical Ozone Production as an Environmentally Friendly Technology for Water Treatment
Authors: Franco Débora V. , Jardim Wilson F. , Boodts Julien F. C. , Da Silva Leonardo M.
Published: January 2008

Perspectives, advances and environmental aspects concerning electrochemical ozone production applied to water purification are presented and discussed in relation to the conventional corona process (silent electric discharge). Ozone generated using a laboratory‐made electrochemical reactor was applied for the discoloration/degradation of dyes used in the Brazilian textile industry and for degradation of endocrine disruptors. A constant ozone load of 0.35 ± 0.02 g/h was used throughout. The study, concerning color removal from dye solutions, revealed that total discoloration is rapidly achieved. The degradation rate of the textile dyes evaluated by TOC is little affected by the dye composition and considerably influenced by the pH and ozonation time. Analysis of the COD/TOC‐ratio indicates that ozonation increases oxidation feasibility of the organic matter (dye by‐products) when compared to the original compounds. Ozonation of mixed aqueous solutions containing different endocrine disruptors revealed these compounds are totally degraded with a very high removal rate.
Qualitative and quantitative analysis of tachykinin NK2 receptors in chemically defined human colonic neuronal pathways
Authors: Jaafari Nadia , Khomitch‐Baud Alexandra , Gilhodes Jean‐Claude , Hua Guoqiang , Julé Yvon
Published: January 2008

The involvement of NK2 receptors (NK2r) in the neuroregulation of human colonic motility has been mainly assessed by using pharmacological approaches. The aim of this study was to characterize the intramural neurons and nerve varicosities expressing NK2r in human colonic neuronal pathways. Neuronal coding in the myenteric plexus and external muscle layers was identified on the basis of the patterns of colocalization of tachykinins (TK), vesicular acetylcholine transporter (VAChT), nitric oxide synthase (NOS), glutamate decarboxylase (GAD), and vasoactive intestinal peptide (VIP) with NK2r immunoreactivity. The proportions of chemically defined synaptophysin‐immunoreactive nerve varicosities were accurately determined by using specific software. NK2r immunoreactivity was detected in the soma of many myenteric neurons (71.8%). A large proportion of these neurons was immunoreactive to VAChT (39.3%), TK (30%), and GAD (23.5%) and, to a lesser extent, to NOS and VIP. The proportions of nerve varicosities expressing NK2r showed significant regional differences: the highest proportion (59.8%) was located in the myenteric plexus. High proportions of the myenteric nerve varicosities expressing NK2r were immunoreactive to VIP (80.9%) and NOS (77.9%), and lower proportions were recorded with VAChT, TK, and GAD. In the circular and longitudinal muscle layers, the proportions of nerve varicosities expressing NK2r were 49.6% and 45.3%, respectively. The chemically defined intramuscular varicosities were closely apposed to smooth muscle cells expressing NK2r. In conclusion, the data obtained in this study, in which the expression of NK2r was mapped in the human colonic neuronal pathways, confirm that these receptors are involved in the neuroneuronal and neuromuscular processes regulating human colonic motility. J. Comp. Neurol. 507:1542–1558, 2008. © 2008 Wiley‐Liss, Inc.
Isthmotectal axons maintain normal arbor size but fail to support normal branch numbers in dark‐reared Xenopus laevis
Authors: Udin Susan B.
Published: January 2008

Developing binocular projections to the Xenopus tectum require visual input in order to establish matching topographic maps. In dark‐reared Xenopus, the ipsilateral eye's map, relayed via the retino‐tecto‐isthmotectal pathway, fails initially to acquire normal rostrocaudal order. Moreover, with extended time in the dark, the ipsilateral map becomes progressively less well organized. This phenomenon showed that without binocular cues, the isthmotectal axons are unable to locate proper sites for their terminal zones but left open the issue of whether the axons are able to establish arbors of normal dimensions and/or to sustain normal numbers of branches. In order to test whether dark‐rearing modifies isthmotectal axon branching, we have used horseradish peroxidase to examine axons of Xenopus after dark‐rearing for periods from 3 to 298 weeks. The results demonstrate that these axons never acquire more than about half the normal numbers of terminals. Surprisingly, however, the dark‐reared axons' terminal zones are normal in mediolateral and rostrocaudal extent despite the lack of binocular cues that normally could constrain arbor size by inducing pruning of branches in regions with mismatched visual inputs. The effects of dark‐rearing are reversible. After a return to normal lighting conditions, the recovery process begins quickly, with a significant increase in branch numbers within 4 weeks. The terminal zone remains of normal dimensions. These results support the hypothesis that correlated binocular visual input is essential for the maintenance of normal numbers of isthmotectal branches but that normal termination zone size can be established in the absence of visual cues. J. Comp. Neurol. J. Comp. Neurol. 507:1559–1570, 2008. © 2008 Wiley‐Liss, Inc.
On the number of reliable finite‐element eigenmodes
Authors: Givoli Dan
Published: January 2008

The finite‐element (FE) approximation of linear elliptic eigenvalue problems is considered. An analysis based on a number of known estimates leads to the simple formula M=r0εd/(2p)N relating the total number of degrees of freedom N, the maximum relative error level ε desired for the eigenvalues, and the number of ‘reliable’ modes M. (Here d is the spatial dimension and p is the polynomial degree of the FE space.) Moreover, a rough estimate for the numerical value of the constant r0 for a given application is found. This result supports a well‐known rule of thumb. Copyright © 2008 John Wiley & Sons, Ltd.
Aqueous enzymatic oil extraction from Irvingia gabonensis seed kernels
Authors: Womeni Hilaire Macaire , Ndjouenkeu Robert , Kapseu César , Mbiapo Félicité Tchouanguep , Parmentier Michel , Fanni Jacques
Published: January 2008

The objective of this study was to extract the fat from Irvingia gabonensis kernels without using organic solvent but by using the enzyme aqueous oil extraction process. The aqueous dispersion of kernel flour of bush mango was treated with a protease (Alcalase®), a pectinase (Pectinex®) and a mixture of cell wall‐degrading enzymes (Viscozyme®) before centrifugation. The yield of oil extracted was calculated in comparison with the chemical extraction method using hexane as solvent. A central composite experimental design was used for the determination of optimized conditions. The results showed that aqueous extraction without enzyme allows recovering 27.4% of the kernel oil. When Alcalase, Pectinex and Viscozyme were added separately, the oil yields were 35.0, 42.2 and 68.0%, respectively. Optimized conditions for Viscozyme resulted in a model of oil yield with a high coefficient of determination (r2 = 0.94). These conditions were the following: kernel‐to‐water ratio 0.11–0.19, concentration of enzyme 1.4–2.0%, and time of incubation 14–18 h. Confirmation of the model led to 83.0% oil yield after treatment of the kernel flour at a kernel‐to‐water ratio of 0.16, using 2% Viscozyme for 18 h. Under the same conditions, followed by addition of 1% Alcalase for 2 h, the yield was 90.0%.
Electrochemistry of Cytochrome P450 2B6 on Electrodes Modified with Zirconium Dioxide Nanoparticles and Platin Components
Authors: Peng Lei , Yang Xiaodi , Zhang Qianqian , Liu Songqin
Published: January 2008

The direct electrochemical and electrocatalytic behavior of the immobilized cytochrome P450 2B6 (CYP2B6) on zirconium dioxide nanoparticles (ZrO2) was investigated. The film of nano‐structured ZrO2that incorporated cytochrome P450 2B6 (CYP2B6) with colloidal paltin, which was stabilized by poly‐lysine (Pt‐PLL), was prepared on glassy carbon electrodes. In anaerobic solutions, the immobilized CYP2B6 exhibited a reversible electron transfer between the heme electroactive center of CYP2B6 and electrodes with a formal potential of −(0.449±0.004) V at pH 7.4. In air‐saturated solutions, an increased bioelectrocatalytic reduction current could be obtained with the CYP2B6‐modified electrode with the addition of anticancer drugs, such as lidocaine. This leads to the construction of disposable biosensors for drugs by utilizing the electrochemical activity and catalytic reactions of the immobilized CYP2B6.
Can forecasting performance be improved by considering the steady state? An application to Swedish inflation and interest rate
Authors: Österholm Pär
Published: January 2008

This paper investigates whether the forecasting performance of Bayesian autoregressive and vector autoregressive models can be improved by incorporating prior beliefs on the steady state of the time series in the system. Traditional methodology is compared to the new framework—in which a mean‐adjusted form of the models is employed—by estimating the models on Swedish inflation and interest rate data from 1980 to 2004. Results show that the out‐of‐sample forecasting ability of the models is practically unchanged for inflation but significantly improved for the interest rate when informative prior distributions on the steady state are provided. The findings in this paper imply that this new methodology could be useful since it allows us to sharpen our forecasts in the presence of potential pitfalls such as near unit root processes and structural breaks, in particular when relying on small samples.  Copyright © 2008 John Wiley & Sons, Ltd.
Secondary Metabolites from the Fungus Chaetomium brasiliense
Authors: Li Guo‐You , Li Bo‐Gang , Yang Tao , Liu Guang‐Ye , Zhang Guo‐Lin
Published: January 2008

Two new depsidones, mollicellins I and J (1 and 2, resp.), and a new chromone, 2‐(hydroxymethyl)‐6‐methylmethyleugenin (3), along with six known compounds, 4–9, were isolated from the ethyl acetate extract of a solid‐state fermented culture of Chaetomium brasiliense. Their structures were elucidated based on spectroscopic analysis. Mollicellins I and H (5) exhibited significant growth inhibitory activity against human breast cancer (Bre04), human lung (Lu04), and human neuroma (N04) cell lines with GI50 values between 2.5–8.6 μg/ml.
Three New Thiophene Acetylenes from Rhaponticum uniflorum (L.) DC.
Authors: Liu Hai‐Li , Guo Yue‐Wei
Published: January 2008

Three new thiophene‐acetylenes, 7‐chloroarctinone‐b (1), rhapontiynethiophenes A (2) and B (3), along with arctinone‐b (4) were isolated from the MeOH extract of the roots of Rhaponticum uniflorum (L.) DC. The structures of the new compounds were elucidated by detailed spectroscopic data analysis and by comparison with known compounds.
Stilbene Derivatives from Gnetum montanumMarkgr. f. megalocarpumMarkgr.
Authors: Wang Li‐Qin , Zhao You‐Xing , Hu Jiang Miao , Jia Ai‐Qun , Zhou Jun
Published: January 2008

Three new stilbene derivatives, gnetumelin A (1), gnetumelin B (2), and gnetumelin C (3), along with the nine known stilbene derivatives 4–12 were isolated from Gnetum montanum Markgr. f. megalocarpum Markgr. Their structures were determined by spectroscopic analysis and comparison of the data with reported ones.
A New Monoterpene Glucoside from the Roots of Paeonia lactiflora
Authors: Kim Ju Sun , Yean Min Hye , Lee Joo Young , Kim Yoon Jung , Lee Eun Ju , Lee So Young , Kang Sam Sik
Published: January 2008

A new monoterpene glucoside, 1‐O‐β‐D‐glucopyranosyl‐8‐O‐benzoylpaeonisuffrone (1), was isolated from the roots of Paeonia lactiflora cultivated in Korea, together with two known compounds 1‐O‐β‐D‐glucopyranosylpaeonisuffrone and paeonidanin (2). Their structures were established on the basis of chemical and spectroscopic methods.
The effects of acute exercise on cognitive functioning and cigarette cravings during temporary abstinence from smoking
Authors: Van Rensburg Kate Janse , Taylor Adrian H.
Published: January 2008

Background

Abstinence from smoking is associated with increased cravings, risk of accidents and self‐reported poor concentration. A single exercise session can reduce cravings and self‐reported poor concentration and can enhance cognitive performance among non‐smokers.

Objective

To assess whether acute exercise impacts on the cognitive performance and cravings of abstaining smokers.

Methods

In a counterbalanced cross‐over design, participants (n = 23) did a 15 min passive or exercise condition, following cigarette abstinence. Cognitive functioning was measured by a computerised version of the Stroop colour‐word interference task. Cravings were measured using the 10‐item, 2‐factor QSU‐Brief and a single item for ‘desire to smoke’. Measures were recorded at baseline, immediately post, 5, 10 and 15‐min post treatment.

Results

A 2‐way ANOVA showed no significant condition × time interaction for cognitive functioning. Significant interaction effects were found for desire to smoke, QSU Factor 1 (desire–behave) and 2 (desire–affect). Exercise reduced cravings for up to 15 min post treatment.

Discussion

Findings support previous research that acute exercise reduces cravings to smoke. Future research should determine if exercise can enhance other objective aspects of cognitive performance, and repeat the present study with a more homogeneous sample, in terms of Stroop performance.

Conclusion

This is the first study to show that exercise can reduce both factors of the QSU‐Brief, but effects on cognitive functioning were not observed. Copyright © 2008 John Wiley & Sons, Ltd.
Authentication of the 31 species of Toxic and Potent Chinese Materia Medica (T/PCMM) by microscopic technique, part 2: Three species of seed T/PCMM
Authors: Xia Li , Bai Li‐Ping , Chu Chu , Li Ping , Jiang Zhi‐Hong , Zhao Zhong‐Zhen
Published: January 2008

Toxic and Potent Chinese Materia Medica (T/PCMM) are being used more and more in the treatment of various diseases. In view of their toxic side effects and to ensure their safe use, accurate and reliable authentication is indispensable. However, identifying characteristics of T/PCMM are seldom reported, even though modern microscopy can provide ample, unique identifying characteristics from cells found in transverse sections and powders. In particular, no systematic authentication studies on seed T/PCMM have been conducted. In the course of our study on 31 T/PCMM originating from plants, animals, minerals, and secreta, an accurate and convenient method, based on microscopic techniques, has been developed and reported for the authentication of animal T/PCMM. The present study deals with detailed investigations on three species of seed T/PCMM, namely Semen Hyoscyami (Hyoscyamus niger L.), Semen Euphorbiae (Euphorbia lathyris L.), and Semen Strychni (Strychnos nux‐vomica L.). The macroscopic characters are here described in detail, and the microscopic characters were conclusively determined by common and polarized light microscopy. Results showed that these three T/PCMM can be easily identified by the present method even when powdered and combined. Thus, the microscopic method is applicable for authentication of the earlier three T/PCMM, and the morphological and microscopic characteristics described here are proposed as parameters to establish the authenticity of these three T/PCMM. Microsc. Res. Tech., 2008. © 2008 Wiley‐Liss, Inc.
Retargeting polymer‐coated adenovirus to the FGF receptor allows productive infection and mediates efficacy in a peritoneal model of human ovarian cancer
Authors: Green Nicola K. , Morrison Joanne , Hale Sarah , Briggs Simon S. , Stevenson Mark , Subr Vladimir , Ulbrich Karel , Chandler Lois , Mautner Vivien , Seymour Leonard W. , Fisher Kerry D.
Published: January 2008

Background

Transductional targeting of adenovirus following systemic or regional delivery remains one of the most difficult challenges for cancer gene medicine. The numerical excess and anatomical advantage of normal (non‐cancer) cells in vivo demand far greater detargeting than is necessary for studies using single cell populations in vitro, and this must be coupled with efficient retargeting to cancer cells.

Methods

Adenovirus (Ad5) particles were coated with reactive poly[N‐(2‐hydroxypropyl)methacrylamide] copolymers, to achieve detargeting, and retargeting ligands were attached to the coating. Receptor‐mediated infection was characterised in vitro and anticancer efficacy was studied in vivo.

Results

Polymer coating prevented the virus binding any cellular receptors and mediated complete detargeting in vitro and in vivo. These fully detargeted vectors were efficiently retargeted with the model ligand FGF2 to infect FGFR‐positive cells. Specific transduction activity was the same as parental virus, and intracellular routing appeared unaffected. Levels of transduction were up to 100‐fold greater than parental virus on CAR negative cells. This level of specificity permitted good efficacy in intraperitoneal cancer virotherapy, simultaneously decreasing peritoneal adhesions seen with parental virus. Following intravenous delivery FGF2 mediated unexpected binding to erythrocytes, improving circulation kinetics, but preventing the targeted virus from leaving the blood stream.

Conclusions

Polymer cloaking enables complete adenovirus detargeting, providing a versatile platform for receptor‐specific retargeting. This approach can efficiently retarget cancer virotherapy in vivo. Ligands should be selected carefully, as non‐specific interactions with non‐target cells (e.g. blood cells) can deplete the pool of therapeutic virus available for targeting disseminated disease. Copyright © 2008 John Wiley & Sons, Ltd.
MRI‐guided cryotherapy
Authors: Morrison Paul R. , Silverman Stuart G. , Tuncali Kemal , Tatli Servet
Published: January 2008

Over the last decade the focus of published research on MRI‐guided cryotherapy has switched from the study of experimental models to the clinical treatment of patients. The latter reports attest to the safety and feasibility of treating lesions in the liver, kidney, and other sites throughout the body. Further, the published images and initial results speak to the utility of MRI for the task of monitoring this specific procedure. This clinical utility is a realization of the promise of the earlier experimental work that showed the clarity with which interstitial ice is seen under MRI under various pulse sequence parameters. Early adopters have taken advantage of access to the patient that is provided by low and mid‐field open scanners; the near future will test the suitability of higher field systems. It has been critical that an FDA‐approved cryotherapy system and suitably thin probes were customized for the MRI environment a decade ago by which percutaneous cryotherapy could be performed. There is still work to be done to expand the role of percutaneous cryotherapy, to understand various tissue responses, and to optimize visualization of therapeutic isotherms. Also, long‐term outcomes need to be assessed. Overall, in a worldwide environment in which the practice of ablation is growing and an appreciation for such therapies is on the rise, the work of these recent years provides sound footing for the advances that lay ahead for clinical MRI‐guided cryotherapy. J. Magn. Reson. Imaging 2008;27:410–420. © 2008 Wiley‐Liss, Inc.
Characterization of archaeological bronze and evaluation of the benzotriazole efficiency in alkali medium
Authors: Hassairi H. , Bousselmi L. , Khosrof S. , Triki E.
Published: January 2008

An analytic study permits us to characterize the altered surface of an archaeological bronze coin and to determine the structure and the composition of the patina covering the whole surface of this artefact. This patina could be interpreted at first sight as a type I patina, with copper product deposits on it, with some punctual and enlarged localized type II corrosion.

To achieve the purpose of this work, we investigate the behaviour of an archaeological bronze in the presence of benzotriazole (BTA) in alkali medium with the intention of getting a better passivity while favouring the formation of a polymeric film on the surface of the working electrode. The behaviour of the considered interface is investigated by electrochemical impedance spectroscopy, in the presence and absence of an oxide layer, according to the immersion time.

At pH = 9, in the presence of 15 mmol/l of BTA, the optimum percentage of inhibition efficiency (IE%) is 67% obtained after 30 min of immersion. A pre‐polarization of the bronze working electrode is realized in order to accommodate the preservation technique used in museums and to improve the formation of the Cu(I)‐BTA polymeric film. The use of a pre‐polarized electrode for 30 min at −35 mV/SCE carries an enhancement of the protection versus the non‐polarized electrode. While comparing the result of our investigation with that obtained using the traditional preservation method, we can establish that using a concentration of BTA 15 times lower, important inhibitor efficiencies (%) of 92 and 97.4%, respectively, for 30 min and 96 h of immersion are reached.
Breakaway properties of film formed on copper and copper alloys in erosion–corrosion by mass transfer equation
Authors: Yabuki A. , Murakami M.
Published: January 2008

Erosion–corrosion tests on copper and three types of copper alloys in a 1 wt% solution of CuCl2 were carried out at various flow velocities using a jet‐in‐slit testing apparatus, which is capable of reproducing various hydrodynamic conditions. A damage profile of a specimen was developed using a surface roughness meter to evaluate locally occurring damage. The damage depth rate for copper, beryllium copper, and a 70/30 copper nickel alloy increased with increasing flow velocity, and suddenly increased at a certain velocity, which is called the breakaway velocity. The breakaway velocities at the central and disturbed part of a specimen were different for each sample, indicating that the hydrodynamic conditions of the flowing solution had an effect. The damage depth rate, calculated from the mass transfer equation, which involved mass transfer in the concentration diffusion layer and in the corrosion product film, could be fitted to the experimental data, suggesting that the mass transfer equation can be applied to the evaluation of erosion–corrosion damage. The corrosion product film was exponentially broken away at velocities higher than the breakaway velocity. The breakaway properties of the corrosion product film were confirmed to be different for each material, since the power of the exponential equation was different for each sample.
Atmospheric corrosion of galvanized steel and aluminium in marine and marine‐industrial environments of Saudi Arabia
Authors: Almarshad A. I. , Syed S.
Published: January 2008

Three‐year exposure programme was carried out in Saudi Arabia at nine test stations with different climatic and pollution conditions. The aim of this study was to evaluate the joint effect of atmospheric pollutants (Cl− and SO2), relative humidity (RH) and temperature (T) on the atmospheric corrosion of galvanized steel (GS) and aluminium (Al). Corrosion rates of the two metals have been obtained by loss of weight after 1, 2 and 3 years exposure. The composition of the corrosion products formed on the specimens was identified by X‐ray diffraction analysis. A classification of the atmospheric corrosion aggressivity of the test sites based both on environmental data and corrosion rate measurements was made according to ISO 9223. In some regions, it can be found that corrosion rate values exceed those established by the ISO standard.
Poly(hydroxyethyl methacrylate)‐Based Macroporous Hydrogels with Disulfide Cross‐Linker
Authors: Andac M. , Plieva F. M. , Denizli A. , Galaev I. Yu. , Mattiasson B.
Published: January 2008

Biodegradable supermacroporous PHEMA cryogels were produced by combining two crosslinkers, poly(ethylene glycol) diacrylate and a newly developed disulfide water soluble crosslinker, N,N′‐bis(methacryloyl)‐L‐cystine. The biodegradable PHEMA cryogels were prepared with gel fraction yields up to 70% and were characterized by highly interconnected pores of micrometer size and good mechanical stability. When subjected to reductive agents like DTT, the biodegradable PHEMA cryogels disintegrated into small pieces. The rate of disintegration was controlled by the crosslinking density in the cryogels and the DTT concentration.

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The Effect of Nanofiller on the Thermomechanical Properties of Polyimide/Clay Nanocomposites
Authors: Mya Khine Yi , Wang Ke , Chen Ling , Lin Ting Ting , Pallathadka Pramoda K. , Pan Jisheng , He Chaobin
Published: January 2008

The interaction between PI and partially exfoliated clay nanofillers is investigated by studying the thermomechanical properties of the resulting nanocomposites by NMR, XPS, XRD, TEM, TGA, TMA, and DMA. XRD and TEM showed more exfoliated structure at ≤2.5 wt.‐% clay and a macrophase separation above 2.5 wt.‐% clay. Td and the storage modulus increased with increasing clay content. A decrease in CTE was observed for clay content ≤2.5 wt.‐% because of the good dispersion of the clay in the polymer and the reduced segmental motion of polymer matrix. NMR confirmed the quality of clay dispersion, and XPS exhibited that the interaction in PI/2.5 wt.‐% clay is much stronger than that in PI/5 wt.‐% clay.

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Tuning the Photoluminescence of Silsesquioxanes with Short Substituted Urea Bridges
Authors: Gómez María L. , Fasce Diana P. , Williams Roberto J. J. , Previtali Carlos M. , Matějka Libor , Pleštil Josef , Brus Jiří
Published: January 2008

The polycondensation of a precursor synthesized by the reaction of 3‐(anilinepropyl)trimethoxysilane with 3‐(isocyanatopropyl)triethoxysilane led to a silsesquioxane bearing a substituted urea group in the short organic bridge. The self‐assembly of organic bridges, analyzed by SAXS and FTIR spectra, could be controlled by varying the conditions of the synthesis. Depending on the size of organic clusters, the silsesquioxane exhibited photoluminescence either in the green or red regions of the spectra, or an emission that could be tuned in the whole visible region by the excitation wavelength.

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Encapsulation and Stabilization of Photo‐Sensitive Antioxidants by Using Polymer Microcapsules with Controlled Phase Heterogeneity
Authors: Koo Bo‐Mi , Jung Jae‐Eun , Han Joo‐Hyun , Kim Jin‐Woong , Han Sang‐Hoon , Chung Dong June , Suh Kyung‐Do
Published: January 2008

We describe a robust method for both encapsulating and stabilizing photo‐sensitive antioxidants in polymer microcapsules prepared by a water‐in‐oil‐in‐water double emulsification and evaporation technique, in which a volatile solvent from the oil layer consisting of poly(methyl methacrylate) and methylene chloride is gradually removed. Using poly(ethylene glycol) (PEG) in this study, we demonstrate that control over its molecular weight allows to tune the phase property of the capsule wall; introducing PEG with high molecular weight results in increased heterogeneity. The heterogeneity of the capsule walls displays an ability to effectively block sunlight, which is essential for improving the molecular stability of photo‐sensitive antioxidants. In this study, we experimentally confirm this by observing natural sunlight‐driven molecular decomposition of a model antioxidant, riboflavin‐5′‐phosphate, in poly (methyl methacrylate) microcapsules.

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Untersuchung der Einflüsse von Substratrauheit und Spritzpartikelgröße auf die Haftung thermisch gespritzter Schichten
Authors: Bach Fr.‐W. , Möhwald K. , Bause T.
Published: January 2008

Der Einfluss der Größen Substratrauheit und Spritzpartikelgröße auf die Haftung thermisch gespritzter Schichten wurde systematisch untersucht. Neben gängigen Spritzwerkstoffen (Cr2O3, WCCo, NiCr) und Spritzverfahren (Atmosphärisches Plasmaspritzen (APS) und Hochgeschwindigkeitsflammspritzen (HVOF)) wurden bei den Untersuchungen auch verschiedene Substratwerkstoffe (Stahl, Edelstahl, Aluminium) berücksichtigt.
Neuentwicklungen für den Verschleiß‐ und Korrosionsschutz beim Plasma‐Pulver‐Auftragschweißen
Authors: Gebert A. , Wocilka D. , Bouaifi B. , Alaluss K. , Matthes K.‐J.
Published: January 2008

Hoch verschleißbeständige karbidhaltige Beschichtungen lassen sich durch Auftragschweißen mittels Plasma‐Pulver‐Auftragschweiß‐Verfahren herstellen. Die Verwendung von Vanadiumkarbid vermeidet unerwünschte Reaktionen mit dem Matrixwerkstoff, so dass hochkorrosionsbeständige Schichten auf Fe‐Basis für den Einsatz im Lebensmittel‐ und Meerwasserbereich und auf Ni‐Basis für den Bereich anorganischer Säurebelastung erzeugt werden können.

Ein kombinierter Test relativiert den Korrosionseinfluss bei kombinierter Beanspruchung durch Abrasivverschleiß‐ und Korrosion und zeigt das Primat des Verschleißabtrages auf das Einsatzverhalten.
Maßgeschneiderte Tribologie durch Laseroberflächenbehandlung
Authors: Vollertsen F. , Habedank G. , Partes K.
Published: January 2008

In der Industrie gibt es sehr unterschiedliche Anforderungen an tribologische Eigenschaften von Oberflächen. Sowohl die Minimierung als auch die Maximierung von Reibung und/oder Verschleiß können gefordert sein. Die Reibungs‐ und Verschleißeigenschaften hängen vom jeweiligen tribologischen System ab, das aus den Reibpartnern, dem Zwischenstoff und dem Umgebungsmedium besteht. Somit werden für jede Anwendung maßgeschneiderte Oberflächen mit speziellen tribologischen Eigenschaften benötigt. Es werden Beispiele zur Untersuchung und Anwendung laserbasierter Prozesse gezeigt, die die Herstellung von Oberflächen mit sehr unterschiedlichen tribologischen Eigenschaften ermöglichen.

Die Wellenlängen, die Leistung, die Intensitätsverteilung und die Strahlqualität der verfügbaren Laser können in einem weiten Bereich variiert werden. Auch die verfügbaren Einrichtungen für die Strahlformung und Strahlführung ermöglichen unterschiedliche Prozesse um Eigenschaften für spezielle Anwendungen maßschneidern zu können. Diese Prozesse sind z. B. das ein‐ oder mehrlagige Laserpulverauftragschweißen um homogene oder gradierte Schichten zu generieren, das Laserlegieren oder –dispergieren und die laserstimulierte Abscheidung von Diamantschichten bei Atmosphärendruck.
Thermisch gespritzte titankarbidverstärkte Eisenbasisschichten als Alternative zu konventionellen karbidischen Werkstoffen
Authors: Bobzin K. , Ernst F. , Zwick J. , Richardt K. , Warda T. , Reisel G.
Published: January 2008

Hochgeschwindigkeitsflammgespritzte karbidbasierte Schichten haben sich in der Industrie als gängiger Korrosions‐ und Verschleißschutz etabliert. Aufgrund der typischen hohen Karbidanteile von über 75 Gewichtsprozenten zeichnen sie sich durch eine sehr hohe Härte und eine exzellente Verschleißbeständigkeit aus. Jedoch erfordern diese Eigenschaften gleichzeitig auch einen erhöhten Aufwand bei der mechanischen Nachbearbeitung der Schichten. Ein kostengünstiger Nachbearbeitungsprozess mit geometrisch definierter Schneide wie etwa Drehen oder Fräsen ist in der Regel nicht anwendbar, so dass jedes gespritzte Aufmaß mittels Schleifens abgetragen werden muss. Um diesem Problem entgegenzutreten, bietet ein neues karbidbasiertes Werkstoffkonzept viel versprechende Ansätze. Titankarbide mit einem reduzierten Anteil von 33 Gewichtsprozenten eingebettet in eine Eisenmatrix ermöglichen ein deutlich verbessertes Verhalten hinsichtlich der Bearbeitbarkeit.

Im Rahmen dieser Arbeit wurde eine Prozessroute zur Herstellung optimierter Pulver entwickelt. Mit entsprechenden Ausgangswerkstoffen sind Spritzversuche durchgeführt worden, um eine Verarbeitbarkeit der titankarbidverstärkten Eisenpulver mittels eines gasbetriebenen und eines flüssigbrennstoffbetriebenen Hochgeschwindigkeitsflammspritz‐Systems (HVOF‐Systems) zu untersuchen. Optimierte Parameter wurden dabei unter Zuhilfenahme der statistischen Versuchsplanung ermittelt. Die Schichten sind im Hinblick auf ihre Mikrostruktur, Härte sowie Phasenzusammensetzung analysiert und mit gesinterten Referenzbauteilen verglichen worden. Des Weiteren wurden die thermisch gespritzten Eisenbasisschichten mit Titankarbidverstärkung wärmebehandelt, um die Resthärtbarkeit der Eisenbasismatrix nach dem thermischen Spritzprozess zu untersuchen.
Antimalarial sulfide trioxanes: a revision of mechanism
Authors: Posner Gary H. , Chang Wonsuk
Published: January 2008

The mechanism by which an antimalarially inactive sulfanyl trioxane reacts with ferrous iron is revised. Although originally proposed to involve a short‐lived high‐valent iron‐oxo intermediate, the revised mechanism involves FeBr2 acting as a weak Lewis acid promoting intramolecular redox chemistry between the peroxide unit and the resident sulfanyl sulfur atom; one of the peroxide oxygen atoms is transferred intramolecularly to the neighboring sulfide sulfur atom, oxidizing it into a sulfoxide and reducing the trioxane into a non‐peroxidic dioxolane. This facile ferrous iron‐triggered conversion of the parent 1,2,4‐trioxane sulfide into the corresponding 1,3‐dioxolane sulfoxide accounts for the observed lack of antimalarial activity of the parent sulfanyl trioxane without invoking the intermediacy of a high‐valent iron‐oxo species. Copyright © 2008 John Wiley & Sons, Ltd.
Aminolysis and pyridinolysis of O‐aryl S‐(4‐nitrophenyl) thiocarbonates in aqueous ethanol. Kinetics and mechanism
Authors: Castro Enrique A. , Aliaga Margarita , Santos José G.
Published: January 2008

The reactions of O‐phenyl S‐(4‐nitrophenyl) thiocarbonate (PNPTC) and O‐(4‐chlorophenyl) S‐(4‐nitrophenyl) thiocarbonate (ClPNPTC) with a series of secondary alicyclic (SA) amines and pyridines are subjected to a kinetic investigation in 44 wt% ethanol–water, at 25.0°C and an ionic strength of 0.2 M. The reactions are followed spectrophotometrically at 420 nm (4‐nitrobenzenethiolate anion appearance). Under amine excess, pseudo‐first‐order rate coefficients (kobs) are found. For all these reactions, plots of kobs vs free amine concentration at constant pH are linear, the slope (kN) being independent of pH. The Brønsted‐type plots (log kN vs pKa of the conjugate acid of the amines) for the reactions of the series of SA amines with PNPTC and ClPNPTC are linear with slopes 0.59 and 0.54, respectively. The values of these slopes are in accordance with a concerted mechanism. The Brønsted‐type plots for the pyridinolysis reactions are biphasic, suggesting a stepwise mechanism with a change in the rate‐determining step, from breakdown to formation of a tetrahedral intermediate, as the basicity of the pyridines increases. Copyright © 2008 John Wiley & Sons, Ltd.
Poly(4‐acryloylmorpholine) oligomers carrying a β‐cyclodextrin residue at one terminus
Authors: Bencini Marco , Ranucci Elisabetta , Ferruti Paolo , Manfredi Amedea , Trotta Francesco , Cavalli Roberta
Published: January 2008

A straightforward synthesis of amphiphilic β‐cyclodextrin‐poly(4‐acryloylmorpholine) (β‐CD‐PACM) polymers of controlled molecular weight, consisting of the radical polymerization of 4‐acryloylmorpholine in the presence of 6‐deoxy‐6‐mercapto‐β‐cyclodextrin (β‐CD‐SH) as chain‐transfer agent, has been established. These derivatives carry a single β‐cyclodextrin (β‐CD) moiety at one terminus and their average molecular weight is in the order of 104. Thus, their β‐CD content is ∼ 10% by weight. No evidence of un‐functionalized PACM was found in the final products. The chain‐transfer constant (CT) of β‐CD‐SH was found to be 1.30 by independently determining the reaction constants of both chain‐transfer and propagation reactions. This ensures that the molecular weight, hence the β‐CD content of the polymers, does not significantly vary with conversion. These β‐CD‐PACM polymers are highly soluble in water as well as in several organic solvents such as chloroform and lower alcohols. They proved capable of solubilizing in water poorly soluble drugs such as 9‐[(2‐hydroxyethoxy)methyl]guanine (Acyclovir) and of gradually releasing them in aqueous systems. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1607–1617, 2008
Precise control of microstructure of functionalized polypropylene synthesized by the ansa‐zirconocene/ MAO catalysts
Authors: Hagihara Hideaki , Ishihara Takeshi , The Ban Hoang , Shiono Takeshi
Published: January 2008

We inclusively investigated polymerization behavior and structure of copolymer in the copolymerization of propylene and alkylaluminum‐protected polar allyl monomers. The control of the arrangement of polar group in the copolymer was discussed. It was proved that the location of polar group could be controlled by zirconocene catalyst and a kind of polar monomer. The indenyl or the 2‐methylindenyl ligands of zirconocene were favored to produce end‐functionalized polymers. It was also found that the trimethylaluminum‐protected allylamine and triisobutylaluminum‐protected allylmercaptan had superior ability in the synthesis of end‐functionalized polypropylene. On the other hand, the 2‐methyl‐4‐phenylindenyl ligand produced the copolymers containing both the end‐polar unit and inner‐polar unit at the polymer chains. Terpolymerization of propylene, polar allyl monomer, and 5‐hexen‐1‐ol was also conducted. The NMR study of the terpolymer revealed that both the 5‐hexen‐1‐ol and the polar allyl monomer were incorporated into the polymer chain. It has also become apparent that the polar allyl monomer units predominantly occupied the chain end, while the 5‐hexen‐1‐ol units were located at the inner of main chain. Consequently, we have achieved the synthesis of functionalized polypropylene in which the arrangement of polar group was precisely controlled. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1738–1748, 2008
The formation of γ‐crystal in long‐chain branched polypropylene under supercritical carbon dioxide
Authors: Liao Ruogu , Yu Wei , Zhou Chixing , Yu Fengyuan , Tian Jinghua
Published: January 2008

The crystallization behavior of long‐chain branched (LCB) polypropylene (PP) in the supercritical carbon dioxide (scCO2) atmosphere was investigated to show the influences of LCB and CO2 on the formation of γ‐crystal. The crystallization experiments were performed in CO2 atmosphere with the pressure from 1.3 to 10.4 MPa and temperature between 90 and 130 °C. The effects of LCB level, CO2 pressure, and crystallization temperature on the content of γ‐crystal were investigated. The results showed that the influence of LCB on the formation of γ‐crystal was obvious when PP was crystallized in CO2. The content of γ‐crystal increased with LCB level and reached a maximum of 88.2%. It could be explained that, as LCB increased the chainfolding energy of PP molecular chain and hindered it from folding back into crystal lamella, which made the formation of γ‐crystal easier. However, CO2 was the key factor in the formation of γ‐crystal, and the influence of CO2 on γ‐crystal was much significant than that of LCB. It was believed that the increase of free volume after dissolving of CO2 in PP was helpful in the formation of γ‐crystal. It was found that the content of γ‐crystal increased almost linearly with CO2 pressure (CO2 content), and the contribution of CO2 to γ‐crystal increased with pressure, while that of LCB increased with temperature. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 441–451, 2008
Screen charge transfer by grounded tip on ferroelectric surfaces
Authors: Kim Yunseok , Kim Jiyoon , Bühlmann Simon , Hong Seungbum , Kim Yong Kwan , Kim Seung‐Hyun , No Kwangsoo
Published: January 2008

We have investigated polarization reversal and charge transfer effects by a grounded tip on 50 nm thick ferroelectric thin films using piezoelectric force microscopy and Kelvin force microscopy. We observed the polarization reversal in the center of written domains, and also identified another mechanism, which is the transfer of screen charges toward the grounded tip. In order to overcome these phenomena, we successfully applied a modified read/write scheme featuring a bias voltage. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Determination of cellular redox status by stable isotope dilution liquid chromatography/mass spectrometry analysis of glutathione and glutathione disulfide
Authors: Zhu Peijuan , Oe Tomoyuki , Blair Ian A.
Published: January 2008

Oxidation of glutathione (GSH) to glutathione disulfide (GSSG) occurs during cellular oxidative stress. The redox potential of the 2GSH/GSSG couple, which is determined by the Nernst equation, provides a means to assess cellular redox status. It is difficult to accurately quantify GSH and GSSG due to the ease with which GSH is oxidized to GSSG during sample preparation. To overcome this problem, a stable isotope dilution liquid chromatography/multiple reaction monitoring mass spectrometry (LC/MRM‐MS) method has been developed using 4‐fluoro‐7‐sulfamoylbenzofurazan (ABD‐F) derivatization. ABD‐F derivatization of the GSH thiol group was rapid, quantitative, and occurred at room temperature. The LC/MRM‐MS method, which requires no sample clean‐up, was validated within the calibration ranges of 5 to 400 nmol/mL in cell lysates for GSH and 0.5 to 40 nmol/mL in cell lysates for GSSG. Calibration curves prepared by adding known concentrations of GSH and GSSG to cell lysates were parallel to the standard curve prepared in buffers. GSH and GSSG concentrations were determined in two monocyte/macrophage RAW 267.4 cell lines with or without 15‐LOX‐1 expression (R15LO and RMock cells, respectively) after treatment with the bifunctional electrophile 4‐oxo‐2(E)‐nonenal (ONE). R15LO cells synthesized much higher concentrations of the lipid hydroperoxide, 15(S)‐hydroperoxyeicosatetraenoic acid (15‐HPETE), which undergoes homolytic decomposition to ONE. GSH was depleted by ONE treatment in both RMock and R15LO cells, leading to significant increases in their redox potentials. However, R15LO cells had higher GSH concentrations (most likely through increased GSH biosynthesis) and had increased resistance to ONE‐mediated GSH depletion than RMock cells. Consequently, R15LO cells had lower reduction potentials at all concentrations of ONE. GSSG concentrations were higher in R15LO cells after ONE treatment when compared with the ONE‐treated RMock cells. This suggests that increased expression of 15(S)‐HPETE modulates the activity of cellular GSH reductases or the transporters involved in removal of GSSG. Copyright © 2008 John Wiley & Sons, Ltd.
An electrospray mass spectrometric method for accurate mass determination of highly acid‐sensitive phosphoramidites
Authors: Kupihár Zoltán , Timár Zoltán , Darula Zsuzsanna , Dellinger Douglas J. , Caruthers Marvin H.
Published: January 2008

An accurate mass determination method utilizing electrospray ionization mass spectrometry is described for analysis of several different types of phosphoramidites that are extremely acid‐sensitive compounds. An earlier method, which applied a LiCl/acetonitrile system, was extended for this special application by using polymeric standards including poly(ethylene glycol) (PEG), poly(ethylene glycol) dimethyl ether (PDE) and poly(propylene glycol) (PPG). Concentrations of standards, samples and LiCl were optimized and potential impurities that affect the analyses were also investigated. Copyright © 2008 John Wiley & Sons, Ltd.