bluuebunny/crossref_metadata_2025 huggingface dataset:
ChemInform Abstract: Synthesis Procedures of Nanocomposites from Gels
Authors: Pivin Jean‐Claude
Published: May 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Transition Metal Complexes with Schiff Base Ligands: 4‐Aminoantipyrine‐Based Derivatives
Authors: Raman N. , Raja S. Johnson , Sakthivel A.
Published: May 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Stereoselective Syntheses of Quaternary Substituted α‐Amino Acids Using Oxazol‐5‐(4H)‐ones
Authors: Mosey Robert A. , Fisk Jason S. , Tepe Jetze J.
Published: May 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: HIV Entry Inhibitors and Their Potential in HIV Therapy
Authors: Qian Keduo , Morris‐Natschke Susan L. , Lee Kuo‐Hsiung
Published: May 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Characteristic Reactions of Group 9 Transition Metal Compounds in Organic Synthesis
Authors: Omae Iwao
Published: May 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Specific Labeling of Peptidoglycan Precursors as a Tool for Bacterial Cell Wall Studies
Authors: van Dam Vincent , Olrichs Nick , Breukink Eefjan
Published: May 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: New Potential of the Classical Biginelli Reaction
Authors: Vdovina S. V. , Mamedov V. A.
Published: May 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Advances in the Synthesis of 4‐Aryl‐ and 4‐Hetarylpyridines
Authors: Gromov S. P. , Fomina M. V.
Published: May 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Transition‐Metal‐Catalyzed Hydroarylation Reactions of Alkynes Through Direct Functionalization of C—H Bonds: A Convenient Tool for Organic Synthesis.
Authors: Kitamura Tsugio
Published: May 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Marriage of Porphyrin Chemistry with Metal‐Catalyzed Reactions
Authors: Shinokubo Hiroshi , Osuka Atsuhiro
Published: May 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Synthesis of Benzannelated Five‐Membered Heteroaromatic Compounds from 2,4,6‐Trinitrotoluene
Authors: Bastrakov Maxim A. , Starosotnikov Alexey M. , Shevelev Svyatoslav A.
Published: May 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Recent Synthetic Approaches Toward Non‐Anomeric Spiroketals in Natural Products
Authors: Favre Sylvain , Vogel Pierre , Gerber‐Lemaire Sandrine
Published: May 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Triazines, Tetrazines and Fused Ring Polyaza Systems
Authors: Goya Pilar , Gomez de la Oliva Cristina
Published: May 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Six‐Membered Ring Systems: Diazines and Benzo Derivatives (2006)
Authors: Mills Keith
Published: May 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Six‐Membered Ring Systems: Diazines and Benzo Derivatives (2005)
Authors: Groziak Michael P.
Published: May 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Five‐Membered Ring Systems: Furans and Benzofurans
Authors: Hou Xue‐Long , Yang Zhen , Yeung Kap‐Sun , Wong Henry N. C.
Published: May 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Oxidative Stress in Psychiatric Disorders: Evidence Base and Therapeutic Implications
Authors: Ng Felicity , Berk Michael , Dean Olivia , Bush Ashley I.
Published: May 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Adherence of Pseudomonas aeruginosa
Authors: Irvin Randall T.
Published: May 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Carbon‐Supported Catalysts for the Chemical Industry
Authors: Arunajatesan Venu , Chen Baoshu , Mobus Konrad , Ostgard Daniel J. , Tacke Thomas , Wolf Dorit
Published: May 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Dumbbell‐Shaped Bisfullerene and Conjugated Oligomer Hybrids
Authors: Zhou Ningzhang , Wang Li , Tobin Mark , Thompson David W. , Zhao Yuming
Published: May 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Discovery of Chemical Reactions Through Multidimensional Screening
Authors: Brummond Kay M. , Loyer‐Drew Jennifer A.
Published: May 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Structures, Energetics and Spectroscopy of Gas Phase Transition Metal Ion — Benzene Complexes
Authors: Duncan Michael A.
Published: May 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Concurrent access control for multi‐user and multi‐processor systems based on trust relationships
Authors: Agudo Isaac , Fernandez‐Gago Carmen , Lopez Javier
Published: May 2009

Concurrent access control is an old problem in many fields in Computer Science. It has been solved in many languages and systems, using mechanisms like monitors or priority queues. Nowadays computers implement multi‐core capabilities. This means that they are virtually capable of execution of processes in parallel. This requires new techniques and open new issues in the field of concurrent access control. Moreover, most operating systems are multi‐user; thus, we have to focus on a multi‐processor multi‐user scenario. Trust becomes a paramount aspect when building distributed applications; the same applies on a lower scale in modern computers. We propose the use of a trust graph that keeps record of the trust relationships of the system and helps in deciding on concurrent access requests. The information encoded in the graph will be used both in order to decide on the access requests and to order granted requests in terms of their associated trust level. Copyright © 2009 John Wiley & Sons, Ltd.
Monoanion BH4−Can Stabilize Zwitterionic Glycine with Dihydrogen Bonds
Authors: Tian Shan Xi , Li Hai‐Bei , Yang Jinlong
Published: May 2009

Unusual strength:In the complex glycine–BH4−, unconventional dihydrogen bonds are predicted. An ultrashort dihydrogen bond BH⋅⋅⋅HN and a very strong interaction of about −41 kcal mol−1) are found in complex3(see structures), in which the zwitterionic glycine is stabilized with a big margin.

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A Perspective on Forward Research and Development Paths for Cost‐Effective Solar Energy Utilization
Authors: Lewis Nathan S.
Published: May 2009

Solar electricity has long been recognized as a potential energy source that holds great promise. Several approaches towards converting sunlight into energy are elaborated in this Viewpoint, and discussed with respect to their feasibility for large‐scale application.

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Identification of novel HMGA2 fusion sequences in lipoma: Evidence that deletion of let‐7 miRNA consensus binding site 1 in the HMGA2 3′ UTR is not critical for HMGA2 transcriptional upregulation
Authors: Wang Xiaoke , Hulshizer Rachael L. , Erickson‐Johnson Michele R. , Flynn Heather C. , Jenkins Robert B. , Lloyd Ricardo V. , Oliveira Andre M.
Published: May 2009

Lipoma is a benign tumor composed of mature adipocytes and one of the most common mesenchymal tumors seen in adults. Rearrangement of HMGA2 in chromosome band 12q15 has been found in ∼60–70% of ordinary lipomas with cytogenetic abnormalities. Herein, we report two novel HMGA2 fusion sequences in lipomas with chromosome 12 rearrangements. Cytogenetic studies showed 12q abnormalities in both cases, and fluorescence in situ hybridization (FISH) confirmed the involvement of HMGA2 in each instance. Rapid amplification of cDNA ends (RACE) PCR experiments revealed that one lipoma contained a fusion of the HMGA2 3′ untranslated region (UTR) to a genomic area downstream of the DYRK2 locus on 12q15; the second lipoma showed a fusion of the HMGA2 3′ UTR to a genomic sequence upstream of the DCN locus on 12q21. In both instances the breakpoint on HMGA2 occurred downstream to let‐7 miRNA (microRNA) consensus binding site (CBS) 1. These two and several other previously reported tumors containing HMGA2 3′ UTR rearrangements show breakpoints after let‐7 miRNA CBS 1, which suggests that the elimination of this miRNA binding site is not critical for driving HMGA2 transcriptional upregulation. © 2009 Wiley‐Liss, Inc.
Barriers to early detection and treatment of head and neck squamous cell carcinoma in African American men
Authors: Carroll William R. , Kohler Connie L. , Carter Vivian L. , Hannon Lonnie , Skipper Joni B. , Rosenthal Eben L.
Published: May 2009

Background.

African Amercians afflicted with head and neck squamous cell carcinoma (HNSCC) have a strikingly worse survival than do whites. One apparent cause is an advanced stage of presentation in African Americans. This study was designed to identify barriers to early treatment among African American men.

Methods.

Twenty‐four African American male HNSCC survivors completed structured interviews. Interviewers elicited the participants' experiences from symptom recognition to receiving definitive care.

Results.

Most participants were seen with advanced‐stage HNSCC. Overall, 10% experienced barriers to obtaining early medical care, though 30% were hesitant to seek care due to perceived barriers. Definitive treatment began for 81% within 3 months of initial care seeking.

Conclusion.

Once participants sought care, most of them received definitive treatment within a reasonable time frame. To explain the advanced stage at presentation, either tumor growth rate was extremely rapid or participants sought care when the tumor was quite advanced. The themes suggested by this elicitation study require further validation. © 2009 Wiley Periodicals, Inc. Head Neck, 2009
Bio‐functionalized star PEG‐coated PVDF surfaces for cytocompatibility‐improved implant components
Authors: Heuts Jean , Salber Jochen , Goldyn Alexandra M. , Janser Romy , Möller Martin , Klee Doris
Published: May 2009

Unmodified and GRGDS peptide‐modified six arm PEG star based hydrogels (Star PEG) have been applied as a multifunctional, easy to handle coating system for textile polyvinylidene fluoride (PVDF) structures, which prevent unspecific protein and cell adsorption and control‐specific cell adhesion. The reactive isocyanate‐terminated Star PEG has been successfully applied to ammonia‐plasma treated two‐ and three‐dimensional PVDF surfaces. Easy modification of the surface hydrogel by mixing in of GRGDS peptide during the coating step or subsequent coupling of GRGDS was determined by TOF‐SIMS. Unmodified and GRGDS‐functionalized hydrogel surfaces show distinct protein repellency, as demonstrated by fluorescence microscopy after incubation with fluorescent labeled proteins and Surface MALDI‐TOF‐Mass Spectroscopy. Cell culture experiments with primary human dermal fibroblasts, primary fetal rat fibroblasts, and human osteoblasts on GRGDS and/or KRSR Star PEG‐modified two‐ and three‐dimensional substrates show advancement in cell adhesion and proliferation compared with untreated PVDF surfaces, whereas pure star PEG‐coated surfaces show no cell adhesion. The combination of protein and cell repellent properties with specific biofunctionality and easy application of the coatings will enable their application for 3D‐scaffolds. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010
Rapid outdoor non‐destructive detection of organic minerals using a portable Raman spectrometer
Authors: Jehlička J. , Vítek P. , Edwards H. G. M. , Hargreaves M. , Čapoun T.
Published: May 2009

Raman spectral signatures have been obtained for a series of organic minerals using a compact portable Raman instrument equipped with 785‐nm laser excitation. Well‐resolved Raman spectra of crystalline salts of carboxylic acids, whewellite and mellite, as well as of the aromatic mineral idrialite were recorded. For comparative purposes, an amorphous fossil resin, baltic amber, was also investigated. The results obtained confirm that portable Raman instruments can be considered as excellent tools for field geological applications, including the detection of organic minerals in the frame of outcrops of sedimentary rocks or coal beds. Organic minerals can be added to the list of established biomarkers, including porphyrins, hydrocarbons and organic acids, which are important for the study with regard to future exobiological missions such as the ESA ExoMars mission to detect the presence of extinct or extant life on Mars. Copyright © 2009 John Wiley & Sons, Ltd.
Raman spectroscopic study of the arsenite minerals leiteite ZnAs2O4, reinerite Zn3(AsO3)2 and cafarsite Ca5(Ti,Fe,Mn)7(AsO3)12·4H2O
Authors: Frost Ray L. , Bahfenne Silmarilly
Published: May 2009

The selected arsenite minerals leiteite, reinerite and cafarsite have been studied by Raman spectroscopy. Density functional theory (DFT) calculations enabled the position of the AsO22− symmetric stretching mode at 839 cm−1, the antisymmetric stretching mode at 813 cm−1 and the deformation mode at 449 cm−1 to be calculated. The Raman spectrum of leiteite shows bands at 804 and 763 cm−1 assigned to the As2O42− symmetric and antisymmetric stretching modes. The most intense Raman band of leiteite is the band at 457 cm−1 and is assigned to the ν2 As2O42− bending mode. A comparison of the Raman spectrum of leiteite is made with the arsenite minerals reinerite and cafarsite. Copyright © 2009 John Wiley & Sons, Ltd.
pH‐dependent surface‐enhanced Raman scattering observation of sulfanilamide on the silver surface
Authors: Zhu Xuan , Wang Na , Zhang Rui , Song Wei , Sun Yiping , Duan Guoping , Ding Wen , Zhang Zongrang , Yang Haifeng
Published: May 2009

Monolayers of sulfanilamide on metallic surface can serve as an ideal model for understanding the interaction mechanism between the metal and the sulfanilamide molecule. In the present paper, the surface‐enhanced Raman scattering (SERS) technique was employed to obtain the SERS spectra of sulfanilamide monolayers formed on the silver surface under different pH values. Assignments of the spectra were carried out with the aid of density functional theory (DFT) calculations (BLYP/6‐311G). It can be found that the adsorption function of sulfanilamide on the silver surface was influenced by the pH value. The fully protonated sulfanilamide molecule adsorbed on the silver surface through N13H2 group and the benzene ring anchored in a relatively perpendicular manner leading to N7H2 and S10O2 groups near the surface, while the completely deprotonated sulfanilamide molecule attached on the silver surface via N7H2 and the benzene ring was perpendicular to, and the N13H2 and S10O2 groups were far from the silver surface. Copyright © 2009 John Wiley & Sons, Ltd.
Complete basis set prediction of methanol isotropic nuclear magnetic shieldings and indirect nuclear spin–spin coupling constants (SSCC) using polarization‐consistent and XZP basis sets and B3LYP and BHandH density functionals
Authors: Kupka Teobald
Published: May 2009

Efficient B3LYP and BHandH density functionals were used to estimate methanol's nuclear magnetic isotropic shieldings and spin–spin coupling constants in the basis set limit. Polarization‐consistent pcS‐n and pcJ‐n (n = 0, 1, 2, 3 and 4), and segmented contracted XZP, where X = D, T, Q and 5, basis sets were used and the results fitted with simple mathematical formulas. The performance of the methods was assessed from comparison with experiment and higher level calculations. 1J(CH) and 3J(HH) values were determined from very diluted solutions in deuterochloroform and compared with theoretical predictions. The agreement between complete basis set (CBS) density functional theory (DFT) predicted isotropic shieldings and spin–spin values and experiment was good. The BHandH/pcS‐n methanol shieldings obtained using structures optimized at the same level of theory are approaching the accuracy of the advanced coupled‐cluster‐singles‐doubles‐approximate triples (CCSD(T)) calculations. Copyright © 2009 John Wiley & Sons, Ltd.
Mononucleotide precedes dinucleotide repeat instability during colorectal tumour development in Lynch syndrome patients
Authors: Ferreira Ana M , Westers Helga , Sousa Sónia , Wu Ying , Niessen Renée C , Olderode‐Berends Maran , van der Sluis Tineke , Reuvekamp Peter TW , Seruca Raquel , Kleibeuker Jan H , Hollema Harry , Sijmons Rolf H , Hofstra Robert MW
Published: May 2009

A progressive accumulation of genetic alterations underlies the adenoma–carcinoma sequence of colorectal cancer. This accumulation of mutations is driven by genetic instability, of which there are different types. Microsatellite instability (MSI) is the predominant type present in the tumours of Lynch syndrome patients and in a subset of sporadic tumours. It is generally accepted that MSI can be found in the early stages of tumour progression, such as adenomas; however, the frequencies reported vary widely among studies. Moreover, data on the qualitative differences between adenomas and carcinomas, or between tumours of hereditary and sporadic origin, are scarce. We compared MSI in samples of colorectal adenoma and colorectal carcinoma in order to identify possible differences along the adenoma–carcinoma sequence. We compared germline mismatch repair (MMR) gene mutation carriers and non‐carriers, to address possible differences of instability patterns between Lynch syndrome patients and patients with sporadic tumours. We found a comparable relative frequency of mono‐ and dinucleotide instability in sporadic colorectal adenomas and carcinomas, dinucleotide instability being observed most frequently in these sporadic tumours. In MMR gene truncating mutation carriers, the profile was different: colorectal adenomas showed predominantly mononucleotide instability and in colorectal carcinomas, also more mononucleotide than dinucleotide instability was detected. We conclude that MSI profiles differ between sporadic and Lynch syndrome tumours, and that mononucleotide marker instability precedes dinucleotide marker instability during colorectal tumour development in Lynch syndrome patients. As mononucleotide MSI proves to be highly sensitive for detecting mutation carriers, we propose the use of mononucleotide markers for the identification of possible Lynch syndrome patients. Copyright © 2009 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Product‐specific sample clean‐up and HPLC analysis of aflatoxins for a dietary product
Authors: Zahn Michael , Jeong Mijeong Lee , Wang Desheng , Trinh Thao , Fay Brooke , Ma Wenwen
Published: May 2009

Introduction

A sample clean‐up procedure has been developed for a complex dietary ingredient, Unigen Inc. (Lacey, WA, USA) product A (a proprietary mixture of Scutellaria baicalensis and Acacia catechu extracts), for the determination of aflatoxins by HPLC.

Objective

To develop an appropriate sample specific clean‐up procedure that removes interferences from the sample for the determination of total aflatoxins B1, B2, G1 and G2 at or lower than 20 ppb by HPLC.

Methodology

The sample specific clean‐up procedure was developed based on the modification of AOAC method 990.33.

Results

Coextract interferences were removed with the clean‐up procedure. The recovery of total aflatoxins was 70% with RSD about 2%; the LOD and LOQ were 1.6 and 5.2 ppb, respectively, for total aflatoxins; the linearity R2 > 0.99. None of the samples tested showed the presence of detectable aflatoxins.

Conclusion

The modified clean‐up method was effective to remove coextract interferences from Unigen product A samples. Copyright © 2009 John Wiley & Sons, Ltd.
Investigation of multi‐walled carbon nanotube‐reinforced high‐density polyethylene/carbon black nanocomposites using electrical, DSC and positron lifetime spectroscopy techniques
Authors: Jeevananda Thimmaraju , Kim Nam Hoon , Lee Joong Hee , Basavarajaiah Siddaramaiah , Deepa Urs MV , Ranganathaiah Chikkakuntappa
Published: May 2009

BACKGROUND: The positive temperature coefficient (PTC) effect on material properties has attracted much attention in recent years due to the prospects of many applications like temperature sensors, thermistors, self‐regulating heaters, etc. It has been suggested that incorporation of multi‐walled carbon nanotubes (MWNTs) into carbon black (CB)‐filled polymers could improve the electrical properties of composites due to high conductivity and network structure and significantly reduce the required CB loading.

RESULTS: We observed no change in melting temperature and crystalline transition temperature on addition of MWNTs. However, the heat of fusion decreases as the amount of conducting carboxylated MWNT (c‐MWNT) filler increases and the resistivity of the composite decreases. The free volume shows an increase up to 1.5 wt% of c‐MWNT content and then decreases.

CONCLUSION: Well‐developed crystals could not be formed due to restricted chain mobility as filler content increases. This results in minimum intermolecular interactions, and thus a decreased heat of fusion. A composite with c‐MWNT content of 0.5 wt% showed the highest PTC and higher resistivity at 150 °C possibly due to the formation of flocculated structures at elevated temperature. For filler content greater than 1.5 wt%, the decrease in free volume may be due to restricted chain mobility. Copyright © 2009 Society of Chemical Industry
Dielectric behaviour and relaxation processes of montmorillonite clay nano‐platelet colloidal suspensions in poly(vinyl pyrrolidone)–ethylene glycol oligomer blends
Authors: Sengwa Ram Jeewan , Choudhary Shobhna , Sankhla Sonu
Published: May 2009

BACKGROUND: Intercalated and exfoliated montmorillonite (MMT) clay structures in polymer matrices improve the thermal, mechanical, electrical and pharmaceutical properties of organic–inorganic materials. Poly(vinyl pyrrolidone) (PVP)–ethylene glycol oligomer (EGO) blends are biocompatible and non‐toxic materials. The dielectric characterization of MMT clay nano‐platelet colloidal suspensions in PVP–EGO blends is important in understanding the ionic conduction behaviour in many complex phenomena occurring in biological systems, and in selective membranes and their use in controlled drug release systems and in liquid electrolytes.

RESULTS: An investigation using dielectric spectroscopy in the 20 Hz to 1 MHz frequency range of MMT clay nano‐platelet colloidal suspensions in PVP–EGO blends confirmed that the PVP segmental motion, ionic conduction relaxation time, electric double layer relaxation time and direct current electrical conductivity are significantly influenced by the clay concentration and EGO chain length. In these materials, ionic motion and PVP segmental dynamics are strongly coupled. Intercalation of EGO structures in clay galleries and exfoliation of clay platelets by adsorption of PVP–EGO structures on clay surfaces are governed by hydrogen bonding interactions between the carbonyl groups of PVP monomer units, the hydroxyl groups of EGOs and the hydroxylated aluminate surfaces of the MMT clay.

CONCLUSION: The dielectric behaviour of intercalated and exfoliated structures of MMT clay nano‐platelet colloidal suspensions in PVP–EGO blends provides a convenient way to obtain liquid organic‐inorganic polymeric nanocomposite electrolytes with tailored ionic conduction properties. Copyright © 2009 Society of Chemical Industry
The effects of dioctyl phthalate plasticization on the morphology and thermal, mechanical, and rheological properties of chemical crosslinked polylactide
Authors: Yang Sen‐Lin , Wu Zhi‐Hua , Meng Bing , Yang Wei
Published: May 2009

The tensile strength and thermal stability of polylactide (PLA) were significantly improved through chemical crosslinking. However, it became much more rigid and brittle. To obtain a material with good thermal stability and enhanced ability to plastic deformation, chemical crosslinked PLA with 0.5 wt % triallyl isocyanurate and 0.5 wt % dicumyl peroxide was blended with different contents of dioctyl phthalate (DOP). The advantage of using DOP is that it does not crystallize, has low glass transition temperature, and is miscible with PLA. The morphology and the thermal and mechanical properties of the crosslinked PLA and the blends of crosslinked PLA with various contents of DOP were investigated by means of scanning electron microscope, differential scanning calorimetry, tensile test, and dynamic mechanical analysis. The rheological properties of samples were also explored by using a capillary rheometer. The results showed that the DOP was an effective plasticizer for the chemical crosslinked PLA, resulting in a significantly decreased Tg, lower yield stress, and improved elongation at break. The plasticization effect was enhanced by adding higher DOP content. In addition, the DOP enhanced the crystallinity of crosslinked PLA, and all the crosslinked samples showed better heat stability than neat PLA. The apparent viscosity of the blends decreased with the increase of DOP content and a phase separation occurred when the content of DOP exceeded 12.5 wt %. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1136–1145, 2009
Atomistic models of three fluorinated polyimides in the amorphous state
Authors: Pandiyan S. , Brown D. , van der Vegt N. F. A. , Neyertz S.
Published: May 2009

Molecular models of three fluorinated polyimides based on the 4,4′‐(hexafluoroisopropylidene)diphthalic dianhydride (6FDA) have been studied using molecular dynamics (MD) simulations. The respective diamines were 4,4′‐hexafluoroisopropylidene dianiline (6FpDA), 3,3′‐hexafluoroisopropylidene dianiline (6FmDA), and 2,4,6‐trimethyl‐1,3phenylenediamine (DAM). Thirty independent samples were prepared using a hybrid pivot Monte Carlo‐MD generation technique and average densities were found to be in very good agreement with experiment. Model structures also agreed with available wide‐angle X‐ray scattering data. Cohesive energies, Hildebrand solubility parameters, fractional free volumes (FFV), void space distributions and intermolecular as well as intramolecular interactions were analyzed. The differences in bulk properties between both 6FDA‐6FpDA and 6FDA‐6FmDA isomers remain fairly small, although the configurations of the former are more extended. 6FDA‐DAM has a lower density, larger intermolecular distances, and higher free volume than the other two polyimides. Results are discussed with respect to their use as matrices for gas separation. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1166–1180, 2009
Pattern formation in PMMA film induced by electric field
Authors: Lyutakov Oleksiy , Hüttel Ivan , Prajzler Václav , Jeřábek Vítězslav , Jančárek Alexander , Hnatowicz Vladimír , Švorčík Václav
Published: May 2009

Micro‐sized patterns were created on thin poly(methyl methacrylate) (PMMA) films by the effect of external field, perpendicular to the film surface. The PMMA film, prepared by spin‐coating onto Si wafer, was heated to the fluid temperature (275 °C) and a linear pattern was created by the effect of electric field produced by a strip electrode. In another experiment, a round pattern was created as a result of local laser heating of the PMMA film under homogenous electrical field. The created patterns were analyzed by optical microscopy and profile meter. The dependence of the form and size of the created patterns on the intensity of the electric field, exposure time, and initial film thickness was examined. Wave guiding property of a linear pattern, produced by the above technique, was examined in a simple experiment. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1131–1135, 2009
Circuit simulation for the dielectric responses of the composites of copper phthalocyanine oligomers and sulfonated polyurethanes by separating the structural elements
Authors: Zhang Juan , Zhu Dan , Matsuo Masaru
Published: May 2009

The copper phthalocyanine (CuPc) oligomer with high dielectric constant was synthesized by the solution method. The FT‐IR and X‐ray diffraction results revealed its chemical structure. The high dielectric constant of CuPc was proved to result from the free movement of charge carriers along the conjugated orbitals. The composites of CuPc and sulfonated polyurethane (PUI) were prepared and the contents of CuPc in the composites were varied from 10 to 50 wt %. The dielectric performance was greatly enhanced for the composite compared with that of average polymers. Different from the behaviors appeared in a common composite with conductive fillers, there is no percolation phenomenon observed in the CuPc/PUI composite, and the dielectric constants of CuPc/PUI composites decreased with the increase in the CuPc content, which is assumed to due to the strong electrostatic interactions between CuPc and PUI. Considering the many‐body interactions within the bulk sample and the contact effect between the bulk sample and the metallic electrode, an equivalent circuit was established to simulate the dielectric behaviors of the composites and computational curve fitting was done. The results were in good agreement, indicating that the dielectric responses of the composites come from both the extrinsic and the intrinsic contributions. The extrinsic was associated with the Maxwell‐Wagner relaxation at the interface between the electrode and the bulk sample, and the intrinsic was associated with the huge dipoles provided by the mobile charges within the CuPc grains and the interaction among them in the bulk composites. A circuit model concerning the universal dielectric response was proposed in describing the intrinsic contribution, which quantitatively verified the strong interaction among the dipoles with the relaxation time, representing the aggregated structure of CuPc when its content was high in the composites. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1146–1155, 2009
Correlation study among oxygen permeability, molecular mobility, and amorphous structure change of poly(ethylene‐vinylalcohol copolymers) by moisture
Authors: Yamamoto Tomoyuki , Kanda Taiji , Nishihara Yuko , Ooshima Tetsuya , Saito Yoichiro
Published: May 2009

Oxygen permeability and the free‐volume hole size (cavity size) of ethylene‐vinylalcohol copolymers (EVOH) indicate abnormal humidity dependence, that is, they have minimum values in the range of around 20–40% RH, not showing a monotonic increase with humidity. To clarify this abnormal phenomenon, we investigated its molecular mobility and amorphous structure change by means of solid‐state NMR and temperature‐modulated differential scanning calorimetry (TMDSC). The glass transition temperature (Tg) decreased with humidity. Specimens stored at 15–60% RH showed large enthalpy relaxation, and it was found that the amorphous structure became more compact and the molecular conformation became more stable by ageing within this range of humidity. Under these conditions, solid‐state NMR measurement showed a component with intermediate relaxation time in the amorphous region. The results obtained by TMDSC and solid‐state NMR showed a reduction in molecular mobility by densifying in the amorphous region under the condition of 15–60% RH. The fact that the oxygen permeability and the cavity size of EVOH indicate minimum values at low humidity are attributed to the reduction in molecular mobility by enthalpy relaxation. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1181–1191, 2009
Effect of PVDF characteristics on extruded film morphology and porous membranes feasibility by stretching
Authors: Sadeghi F. , Tabatabaei S. H. , Ajji A. , Carreau P. J.
Published: May 2009

Three different polyvinylidene fluoride (PVDF) resins were selected to develop porous membranes through melt extrusion and stretching. The effect of the polymer rheology on chain elongation in the melt state was studied. The possibility of generating a row‐nucleated lamellar crystallization for precursor films was investigated. The arrangement and orientation of the crystalline phase were examined by wide angle X‐ray diffraction (WAXD) and Fourier Transform Infrared Spectroscopy (FTIR). The extrusion conditions and the blend compositions were adjusted to obtain uniform precursor films with appropriate morphology. Annealing, cold and hot stretching were consequently employed to generate and enlarge the pores. It was found that a proper crystalline structure of the precursor films was strongly dependent on molecular weight of PVDF and process conditions. Blending of two PVDF resins having low and high molecular weights improved the water vapor permeability of the obtained membranes. The tensile response was monitored during the stretching process for membrane development and the results revealed a distinct behavior for the membranes having low or high permeability. The membranes with low permeability did not show any significant strain hardening during stretching whereas for highly permeable membranes, a noticeable strain hardening behavior was observed. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1219–1229, 2009
Management of panic disorder in the primary‐care setting
Authors: Davies Simon , Nash Jon , Nutt David
Published: May 2009

Panic disorder, characterised by attacks of fear or anxiety over a discrete period and with a rapid onset, frequently presents in primary care. Here, the authors describe its diagnosis and management. Copyright © 2009 Wiley Interface Ltd
Electronic structure and magnetic properties of Cu‐doped SnO2 from first‐principles study
Authors: Zhang Chang‐wen , Kao Hong , Dong Jian‐min , Li Ping
Published: May 2009

We have studied the electronic structure of Cu‐doped SnO2, with different possible geometrical sites for the Cu dopant, to determine the most favored magnetic properties. Our study shows that each Cu has spin‐polarized states in the band gap generating a magnetic moment 2.0μB. We also find Cu impurities tend to form clusters which induces strong ferromagnetism with high Curie temperature, through the same p–d hopping interactions as found in Sr2FeMoO6 [Phys. Rev. Lett. 85, 2549 (2000)]. Doped p‐type carriers enhanced the ferromagnetism, while n‐type carriers are detrimental to ferromagnetism due to charge compensating effects, indicating that the strong ferromagnetism in Cu‐doped SnO2 would be achieved by hole doping. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Locally Delivered Growth Factor Enhances the Angiogenic Efficacy of Adipose-Derived Stromal Cells Transplanted to Ischemic Limbs
Authors: Bhang Suk Ho , Cho Seung-Woo , Lim Jae Min , Kang Jin Muk , Lee Tae-Jin , Yang Hee Seok , Song Young Soo , Park Moon Hyang , Kim Hyo-Soo , Yoo Kyung-Jong , Jang Yangsoo , Langer Robert , Anderson Daniel G. , Kim Byung-Soo
Published: May 2009

Ischemia is a potentially fatal medical event that is associated with as many as 30% of all deaths. Stem cell therapy offers significant therapeutic promise, but poor survival following transplantation to ischemic tissue limits its efficacy. Here we demonstrate that nanosphere-mediated growth factor delivery can enhance the survival of transplanted human adipose-derived stromal cells (hADSCs) and secretion of human angiogenic growth factors per cell, and substantially improve therapeutic efficacy of hADSCs. In vitro, in hypoxic (1% oxygen) and serum-deprived conditions that simulate in vivo ischemia, fibroblast growth factor-2 (FGF2) significantly reduced hADSC apoptosis and enhanced angiogenic growth factor secretion. In vivo, hADSCs delivered intramuscularly into ischemic hind limbs in combination with FGF2 resulted in significant improvements in limb survival and blood perfusion, as well as survival of the transplanted hADSCs and secretion of human angiogenic growth factors (i.e., vascular endothelial growth factor, hepatocyte growth factor, and FGF2). Interestingly, the majority of transplanted hADSCs were localized adjacent to the microvessels rather than being incorporated into them, suggesting that their major contribution to angiogenesis might be to increase paracrine secretion of angiogenic growth factors. This study demonstrates the potential of hADSCs in combination with growth factors for use in the treatment of ischemia.

Disclosure of potential conflicts of interest is found at the end of this article.
Generation of Pancreatic Hormone-Expressing Islet-Like Cell Aggregates from Murine Adipose Tissue-Derived Stem Cells
Authors: Chandra Vikash , G Swetha , Phadnis Smruti , Nair Prabha D. , Bhonde Ramesh R.
Published: May 2009

The success of cell replacement therapy for diabetes depends on the availability and generation of an adequate number of islets, preferably from an autologous origin. Stem cells are now being probed for the generation of physiologically competent, insulin-producing cells. In this investigation, we explored the potential of adipose tissue-derived stem cells (ASCs) to differentiate into pancreatic hormone-expressing islet-like cell aggregates (ICAs). We initiated ASC culture from epididymal fat pads of Swiss albino mice to obtain mesenchymal cells, murine epididymal (mE)-ASCs. Subsequent single-cell cloning resulted in a homogeneous cell population with a CD29+CD44+Sca-1+ surface antigen expression profile. We formulated a 10-day differentiation protocol to generate insulin-expressing ICAs from mE-ASCs by progressively changing the differentiation cocktail on day 1, day 3, and day 5. Our stage-specific approach successfully differentiated mesodermic mE-ASCs into definitive endoderm (cells expressing Sox17, Foxa2, GATA-4, and cytokeratin [CK]-19), then into pancreatic endoderm (cells expressing pancreatic and duodenal homeobox [PDX]-1, Ngn3, NeuroD, Pax4, and glucose transporter 2), and finally into cells expressing pancreatic hormones (insulin, glucagon, somatostatin). Fluorescence-activated cell sorting analysis showed that day 5 ICAs contained 64.84% ± 7.03% PDX-1+ cells, and in day 10 mature ICAs, 48.17% ± 3% of cells expressed C-peptide. Day 10 ICAs released C-peptide in a glucose-dependent manner, exhibiting in vitro functionality. Electron microscopy of day 10 ICAs revealed the presence of numerous secretory granules within the cell cytoplasm. Calcium alginate-encapsulated day 10 ICAs (1,000–1,200), when transplanted i.p. into streptozotocin-induced diabetic mice, restored normoglycemia within 2 weeks. The data presented here demonstrate the feasibility of using ASCs as a source of autologous stem cells to differentiate into the pancreatic lineage.

Disclosure of potential conflicts of interest is found at the end of this article.
Electrochemical oxidative formation of ordered monolayers of thiol molecules on Au(111) surface
Authors: Uosaki Kohei
Published: May 2009

Electrochemical oxidative formation of thiolate monolayers on a Au(111) surface in KOH ethanol solutions of various thiol concentrations is described. The formation process was investigated by electrochemistry, in situ scanning tunneling microscopy (STM), and surface X‐ray diffraction (SXRD). The reductive charge in the linear sweep voltammogram after keeping the potential at +0.1 V increased with holding time and reached the saturated value of 103 µC cm−2, corresponding to the full monolayer coverage of the ($\sqrt{3}\times\sqrt{3}$) structure. The desorption peak shifted negatively with holding time even after the monolayer was formed, suggesting that ordering of the monolayer requires a much longer time than full coverage adsorption. The herringbone structure, corresponding to the ($\sqrt{3}\times 23$ × 23) structure, was observed on the Au(111) surface in KOH ethanol solution by in situ STM, which shows that a clean surface was exposed. When hexanethiol ethanol solution was added into the ethanol solution at −450 mV so that the final thiol concentration was higher than ca. 5 µM, generation of vacancy islands (VIs) was observed, which shows the potentiostatic monolayer formation. When the potential was scanned positively from −950 mV where a clean reconstructed Au(111) surface was exposed, generation of VIs was observed accompanied by anodic current flow. During both oxidative adsorption and reductive desorption of the monolayer, the shape of the steps of the gold surface changed drastically, which suggests that the gold atoms on the surface are extremely mobile during the monolayer formation. SXRD measurement confirmed the surface reconstruction lifting upon monolayer formation. © 2009 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 9: 199–209; 2009: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.200900002
Feasibility of Intraoperative Neuromonitoring During Thyroid Surgery After Administration of Nondepolarizing Neuromuscular Blocking Agents
Authors: Chu Koung‐Shing , Wu Sheng‐Hua , Lu I‐Cheng , Tsai Cheng‐Jing , Wu Che‐Wei , Kuo Wen‐Rei , Lee Ka‐Wo , Chiang Feng‐Yu
Published: May 2009

Background

A short‐acting depolarizing neuromuscular blocking agent (NMBA), succinylcholine, has been utilized for thyroid operations with intraoperative neuromonitoring (IONM). Because of its potential to cause serious side effects, this prospective study tried to determine the feasibility of IONM after administration of a nondepolarizing NMBA during thyroid operations.

Methods

Complete IONM data for 179 patients who had normal cord mobility were investigated: 90 patients received an induction dose of rocuronium (group R) and 89 received atracurium (group A). Electromyography signals were obtained from the vagus nerve before and after resection of the thyroid lobe and were defined as V1 and V2 signals, respectively. Accelerometry (percent twitch) was used to monitor the quantitative degree of neuromuscular blockade.

Results

V1 and V2 signals were obtained successfully in all patients. The percent twitch at the V1 signal was significantly lower than that at the V2 signal in both groups (39% ± 20% vs. 69% ± 26% in group R; 35% ± 28% vs. 56% ± 35 % in group A; both p < 0.01). However, the magnitude of the V1 and V2 signals did not differ significantly in either in group (473.8 ± 290.8 μV vs. 528 ± 316.2 μV in group R; 584.8 ± 394.3 μV vs. 637.8 ± 458.2 μV in group A; both p > 0.05).

Conclusions

A single dose of either rocuronium or atracurium was feasible for IONM during thyroid surgery and provided adequate muscle relaxation for tracheal intubation.