bluuebunny/crossref_metadata_2025 huggingface dataset:
Memory complaints and increased rates of brain atrophy: risk factors for mild cognitive impairment and Alzheimer's disease
Authors: Archer H. A. , Kennedy J. , Barnes J. , Pepple T. , Boyes R. , Randlesome K. , Clegg S. , Leung K. K. , Ourselin S. , Frost C. , Rossor M. N. , Fox N. C.
Published: January 2010

Aim

To determine rates of cerebral atrophy in individuals with symptoms of memory loss but no objective cognitive impairment (SNCI) and their association with future cognitive decline.

Methods

Thirty‐two SNCI subjects, 16 with mild cognitive impairment (MCI) and 27 control subjects had clinical assessment and magnetic resonance imaging at baseline and 1 year later. Rates of whole brain atrophy (WBA), hippocampal atrophy (HA) and ventricular enlargement (VE) were measured. Our outcome was clinical diagnosis at 2 years after entry into the study.

Results

The MCI group had greater rates of WBA, HA and VE than both controls and SNCI subjects. As a group SNCI subjects did not have significantly greater rates of atrophy than the controls. However, SNCI subjects who progressed to MCI or dementia had increased rates of atrophy compared with those who remained stable.

Discussion

Individuals with memory complaints but no objective memory deficits, who progress to MCI or dementia, have increased rates of cerebral atrophy. Copyright © 2010 John Wiley & Sons, Ltd.
Characterization of side population cells from laryngeal cancer cell lines
Authors: Wan Guanglun , Zhou Liang , Xie Ming , Chen Hui , Tian Jie
Published: January 2010

Background

Analysis of the hematopoietic system has shown that bone marrow stem cells contain a subpopulation that effluxes the DNA binding dye, Hoechst 33342, out of the cell membrane. These cells are called side population (SP) cells and have been shown to have stem cell characteristics. SP cells have already been found in solid tumors, although there are no published reports examining the role of SP cells in human laryngeal cancer.

Methods

SP cells were identified in the laryngeal cancer cell lines, AMC‐HN‐8 (head and neck cancer cell line 8, from the Asan Medical Center) and Hep‐2 (human epithelial type 2) cell lines, by flow cytometry. Hep‐2 SP cells were isolated and analyzed in proliferation assays, differentiation studies, radiotherapy resistance studies, and tumorigenesis ability.

Results

The AMC‐HN‐8 and Hep‐2 cell lines contained 11.8 ± 1.7% and 17.1 ± 2.0% SP cells, respectively. SP cell proportion was reduced by verapamil. Hep‐2 SP cells exhibited higher self‐regeneration, proliferation, radiotherapy resistance, and tumorigenicity.

Conclusions

SP cells purified from the Hep‐2 cell line harbor cancer stem cell–like properties, and they are heterogeneous, indicating that SP cells are not identical to stem cells. © 2010 Wiley Periodicals, Inc. Head Neck, 2010
Trichocarpinine, a Novel Hetidine–Hetisine Type Bisditerpenoid Alkaloid from Aconitum tanguticum var. trichocarpum
Authors: Lin Ling , Chen Dong‐Lin , Liu Xiao‐Yu , Chen Qiao‐Hong , Wang Feng‐Peng
Published: January 2010

Trichocarpinine (1), the first hetidine–hetisine type bisditerpenoid alkaloid, was isolated from the whole herbs of Aconitum tanguticum var. trichocarpum. Its structure was determined by a combination of spectroscopic techniques, including HR‐ESI‐MS and 1D‐ and 2D‐NMR experiments. Its plausible biogenetic pathway was proposed as well (Scheme).
Oleanane Saponins from Rhizome of Anemone raddeana
Authors: Fan Li , Lu Jincai , Xu Beibei , Gao Song , Zhang Hongfen , Liu Runxiang
Published: January 2010

Two new oleanolic acid‐type triterpenoid saponins, raddeanosides R22 and R23 (1 and 2, resp.), together with four known saponins were isolated from the rhizome of Anemone raddeana Regel. The structures of the new compounds were elucidated as oleanolic acid 3‐O‐β‐D‐glucopyranosyl(1→2)[β‐D‐glucopyranosyl(1→4)]‐α‐L‐arabinopyranoside (1) and oleanolic acid 3‐O‐α‐L‐arabinopyranosyl(1→3)‐α‐L‐rhamnopyranosyl(1→2)[β‐D‐glucopyranosyl(1→4)]‐α‐L‐arabinopyranoside (2). The four known compounds were identified as oleanolic acid 3‐O‐α‐L‐arabinopyranoside (3), oleanolic acid 3‐O‐β‐D‐glucopyranosyl(1→4)‐α‐L‐arabinopyranoside (4), hederasaponin B (5), and hederacholchiside E (6) on the basis of chemical and spectral evidences. Compound 4 is reported for the first time from the Anemone genus, while the other three known compounds have been already found in this plant.
A womb with a view: ultrasound for evaluation of fetal neurobehavioral development
Authors: Emory Eugene K.
Published: January 2010

This commentary offers a brief historical perspective that anticipated contemporary studies of fetal behavior and delineates two divergent trends that have merged in the development of ‘Fetal Psychology’. Focusing on ultrasound imaging as a technological advance for the study of fetal behavior, the paper discusses promises and pitfalls that arise when new methodologies are adopted. While fetal ultrasound has been in use for over half a century, the technology is fast becoming the gold standard for fetal behavioral studies. In this context, the Hata et al. study is discussed. A more recent use of ultrasound is its adaptation to investigations of fetal brain development. This effort, along with the on‐going studies of prenatal brain–behavior relationships, places the work within a developmental neuroscience context. The paper gives a hint of the promise such applications have with a sample of the author's recent work on fetal brain laterality, and speculates that major discoveries regarding human neurobehavioral development lay ahead as the field of fetal psychology matures. Copyright © 2010 John Wiley & Sons, Ltd.
Epstein‐Barr virus infection in immortalized nasopharyngeal epithelial cells: Regulation of infection and phenotypic characterization
Authors: Tsang Chi Man , Zhang Guitao , Seto Eri , Takada Kenzo , Deng Wen , Yip Yim Ling , Man Cornelia , Hau Pok Man , Chen Honglin , Cao Ya , Lo Kwok Wai , Middeldorp Jaap M. , Cheung Annie Lai Man , Tsao Sai Wah
Published: January 2010

Epstein‐Barr virus (EBV) infection has been postulated to be an early event involved in the pathogenesis of nasopharyngeal carcinomas (NPC). The lack of representative premalignant nasopharyngeal epithelial cell system for EBV infection has hampered research investigation into the regulation and involvement of EBV infection in NPC pathogenesis. We have compared the efficiency of EBV infection in nasopharyngeal epithelial cells with different biological properties including immortalized, primary and cancerous nasopharyngeal epithelial cells. EBV infection could be achieved in all the nasopharyngeal epithelial cells examined with variable infection rate. TGF‐β effectively enhanced EBV infection into nasopharyngeal epithelial cells both in the immortalized and primary nasopharyngeal epithelial cells. Stable infection of EBV was achieved in a telomerase‐immortalized nasopharyngeal epithelial cell line, NP460hTert. The expression pattern of EBV‐encoded genes and biological properties of this EBV infected cell line on long‐term propagation were monitored. The EBV‐infected nasopharyngeal epithelial cells acquired anchorage‐independent growth and exhibited invasive growth properties on prolonged propagation. A distinguished feature of this EBV‐infected nasopharyngeal epithelial cell model was its enhanced ability to survive under growth factor and nutrient starvation. This was evidenced by the suppressed activation of apoptotic markers and sustained activation of pAkt of EBV‐infected cells compared to control cells under nutrient starvation. Examination of cytokine profiles of EBV‐infected NP460hTert cells to nutrient and growth factor deprivation revealed upregulation of expression of MCP‐1 and GRO‐α. The establishment of a stable EBV infection model of premalignant nasopharyngeal epithelial cells will facilitate research investigation into the pathogenic role of EBV in NPC development.
Validation of the CDC biofilm reactor as a dynamic model for assessment of encrustation formation on urological device materials
Authors: Gilmore Brendan F. , Hamill Turlough M. , Jones David S. , Gorman Sean P.
Published: January 2010

Contemporary medical science is reliant upon the rational selection and utilization of devices, and therefore, an increasing need has developed for in vitro systems aimed at replicating the conditions to which urological devices will be subjected to during their use in vivo. We report the development and validation of a novel continuous flow encrustation model based on the commercially available CDC biofilm reactor. Proteus mirabilis‐induced encrustation formation on test biomaterial sections under varying experimental parameters was analyzed by X‐ray diffraction, infrared‐ and Raman spectroscopy and by scanning electron microscopy. The model system produced encrusted deposits similar to those observed in archived clinical samples. Results obtained for the system are highly reproducible with encrustation being rapidly deposited on test biomaterial sections. This model will have utility in the rapid screening of encrustation behavior of biomaterials for use in urological applications. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010
Sonographic findings in a patient with neurofibromatosis type 1 and a gastrointestinal stromal tumor
Authors: Girtler Marie‐Theres , De Zordo Tobias , Romagnoli Cesare
Published: January 2010

Gastrointestinal stromal tumors (GIST) have been suggested to be the most common neurofibromatosis 1‐associated gastrointestinal tumors. This case report describes and compares US and CT findings of both abdominal neurofibromas and a gastrointestinal stromal tumor. On US, the GIST appeared as a well‐defined inhomogeneous lesion with a target‐like pattern similar to CT. The neurofibromas appeared as well‐demarcated round nodules with a relatively homogeneous hypoechoic internal structure and were accompanied by subtle posterior acoustic enhancement. US and CT were able to differentiate between neurofibromatomas and GIST in this neurofibromatosis 1 patient; however, a biopsy of the suspicious mass was performed to clarify the diagnosis. © 2010 Wiley Periodicals, Inc. J Clin Ultrasound 2010
Developmental changes in the expression of the Atp7a gene in the liver of mice during the postnatal period
Authors: Lenartowicz Małgorzata , Wieczerzak Krzysztof , Krzeptowski Wojciech , Dobosz Paulina , Grzmil Paweł , Starzyński Rafał , Lipiński Paweł
Published: January 2010

In all living organisms trace element metabolism and transport are closely regulated at the genetic level. Copper is one of the essential microelements required for normal growth and development. The main organ in mammals involved in copper metabolism is the liver. It is known that copper metabolism in the liver is controlled by ATP7B, a P‐type ATP‐ase encoded by the Atp7b gene. However, little is known about the expression and function of the second important P‐type ATP‐ase, ATP7A encoded by the Atp7a gene. In this study we investigated the expression of the Atp7a gene in the liver during postnatal development in mice. We analyzed expression of Atp7a gene in the livers from neonatal (P.05), young (P14) and adult (P240) mice using RT‐PCR and real‐time PCR method. We found a transcript of the Atp7a gene in the liver of all investigated animals. Moreover, we found that the expression of the Atp7a gene in the liver in mice is age‐dependent and decreases during postnatal development. Interestingly, the Atp7a expression in adult mice is very low in comparison with neonatal and young animals. Western blot analysis revealed that Atp7a is expressed not only at mRNA level but also at the protein level in the liver of all investigated animals. The expression of Atp7a gene and ATP7A protein was also confirmed in primary hepatocytes from adult mouse. Demonstration of the hepatic Atp7a gene expression may shed light on new aspects of copper metabolism in the liver in mammals. J. Exp. Zool. 313A:209–217, 2010. © 2010 Wiley‐Liss, Inc.
Sperm motility adaptation to ion‐differing aquatic environments in the Tanganyikan cichlid, Astatotilapia burtoni
Authors: Morita Masaya , Awata Satoshi , Takahashi Tetsumi , Takemura Akihiro , Kohda Masanori
Published: January 2010

The cichlid fish, Astatotilapia burtoni, can acclimate and reproduce in both the K+‐, Na+‐, and Ca2+‐rich waters of Lake Tanganyika (pH 8.9–9.2) and the surrounding rivers where K+, Na+, and Ca2+ concentrations are low (pH 6.5). In this study, we compared sperm motility features among A. burtoni inhabiting the lake, those living in the surrounding rivers, and those from rivers that acclimates to lake water. Sperm of all three groups required extracellular Ca2+ ([Ca2+]o) for sperm motility activation. However, involvement of K+ and Na+ were different. In sperm motility initiation of lake population, the decrease in Na+ and increase in K+ concentrations corresponding to a decrease in [Na+]o/[K+]o was required. In contrast, sperm motility in both the river population and those acclimated to lake water were activated only by a decrease in [Na+]o, suggesting that motility initiation cues regarding Na+ and K+ are different among populations within same species. One probable reason why the difference of initiation cues is that the concentration of K+ in the river water (40 mM) is lower than that in the lake water (110 mM). These results suggest that sperm flagellar activation cascades of river and lake populations within this species differ as a result of adaptations to different ionic environments. J. Exp. Zool. 313A:169–177, 2010. © 2010 Wiley‐Liss, Inc.
Transplantation of galectin‐1‐expressing human neural stem cells into the injured spinal cord of adult common marmosets
Authors: Yamane Junichi , Nakamura Masaya , Iwanami Akio , Sakaguchi Masanori , Katoh Hiroyuki , Yamada Masayuki , Momoshima Suketaka , Miyao Sachiyo , Ishii Ken , Tamaoki Norikazu , Nomura Tatsuji , Okano Hirotaka James , Kanemura Yonehiro , Toyama Yoshiaki , Okano Hideyuki
Published: January 2010

Delayed transplantation of neural stem/progenitor cells (NS/PCs) into the injured spinal cord can promote functional recovery in adult rats and monkeys. To enhance the functional recovery after NS/PC transplantation, we focused on galectin‐1, a carbohydrate‐binding protein with pleiotropic roles in cell growth, differentiation, apoptosis, and neurite outgrowth. Here, to determine the combined therapeutic effect of NS/PC transplantation and galectin‐1 on spinal cord injury (SCI), human NS/PCs were transfected by lentivirus with galectin‐1 and green fluorescent protein (GFP), (Gal‐NS/PCs) or GFP alone (GFP‐NS/PCs), expanded in vitro, and then transplanted into the spinal cord of adult common marmosets, 9 days after contusive cervical SCI. The animals' motor function was evaluated by their spontaneous motor activity, bar grip power, and performance on a treadmill test. Histological analyses revealed that the grafted human NS/PCs survived and differentiated into neurons, astrocytes, and oligodendrocytes. There were significant differences in the myelinated area, corticospinal fibers, and serotonergic fibers among the Gal‐NS/PC, GFP‐NS/PC, vehicle‐control, and sham‐operated groups. The Gal‐NS/PC‐grafted animals showed a better performance on all the behavioral tests compared with the other groups. These findings suggest that Gal‐NS/PCs have better therapeutic potential than NS/PCs for SCI in nonhuman primates and that human Gal‐NS/PC transplantation might be a feasible treatment for human SCI. © 2010 Wiley‐Liss, Inc.
Phase stability and homogeneity in undoped and Mn‐doped LiFePO4 under laser heating
Authors: Galinetto Pietro , Mozzati Maria Cristina , Grandi Marco Simone , Bini Marcella , Capsoni Doretta , Ferrari Stefania , Massarotti Vincenzo
Published: January 2010

Thermal stability and phase homogeneity of the triphylite LiFePO4 compound were investigated by means of Raman spectroscopy. A detailed check of phase homogeneity of undoped samples obtained from different preparation routes—hydrothermal, sol–gel, and solid state synthesis—and Mn‐doped compounds from solid‐state synthesis was performed by means of a mapping of the Raman spectra. The triphylite compositional and structural properties were carefully investigated also with the help of structural refinements and magnetic techniques, which also allowed us to reveal and identify the impurity phases formed together with the olivine LiFePO4. The effect of laser irradiation on the triphylite thermal stability was thoroughly investigated and related to the synthesis route, to the doping, and to the sample homogeneity. The thermal stability of iron oxides, present both as synthesis products and as consequence of the irradiation itself, was also analyzed following the magnetite→maghemite→hematite phase transformation. All the experimental observations concur in indicating that the effectiveness of the laser heating on these compounds mainly depends on grain size and the degree of order of the olivine structure, the highest thermal stability being displayed in the case of the nonhomogenous undoped samples obtained from solid‐state preparation, which show a highly ordered triphylite phase. Copyright © 2010 John Wiley & Sons, Ltd.
The SERS response of semiordered Ag nanorod arrays fabricated by template oblique angle deposition
Authors: Liu Y.‐J. , Zhang Z.‐Y. , Dluhy R. A. , Zhao Y.‐P.
Published: January 2010

Semiordered Ag nanorod arrays are fabricated by template oblique angle deposition (OAD) using regular Au nano‐post arrays with different diameters as seed patterns. The Au nano‐post arrays do not give an observable surface‐enhanced Raman scattering (SERS) activity under our detection configuration, whereas the patterned Ag nanorod arrays can produce a very strong SERS signal. These SERS intensities increase monotonically with the decrease in the diameter and separation of the Ag nanorods, which demonstrates that one can improve the SERS detection by tuning the diameter and separation of the Ag nanorods, and the template OAD method can help produce more uniform, reproducible, and sensitive Ag nanorod SERS substrates. Copyright © 2010 John Wiley & Sons, Ltd.
Trans–cis isomerisation of the carotenoid lycopene upon complexation with cholesteric polyester carriers investigated by Raman spectroscopy and density functional theory
Authors: López‐Ramírez, M. R. , Sanchez‐Cortes S. , Pérez‐Méndez M. , Blanch G.
Published: January 2010

Raman spectroscopy and density functional theory (DFT) were used in this work for the structural characterisation of lycopene, the antioxidant carotenoid, and its complexes with two synthetic thermotropic cholesteric polyesters. Both polyesters were employed successfully to encapsulate the carotenoid lycopene (Lyc). Besides protecting it from oxidation, they induced the trans–cis isomerisation of lycopene towards the more biologically active and bioavailable isomer cis‐Lyc. The Raman spectra revealed changes mainly concerning the band ν1 and bands of methyl groups. This would explain the interaction mechanism between lycopene and cholesteric polyesters, inducing structural changes in the carotenoid by formation of a cis CC bond in central positions of the isomer chain and hydrophobic interaction that affects the side methyl groups. DFT calculations confirmed that the isomerisation occurs at central positions of lycopene molecule. The analysis of ν1 and ν2 bands and those of methyl groups in the calculated spectra of lycopene indicates that the interaction with the synthetic cholesteric polyesters could mainly lead to the 13‐cis‐Lyc isomer. The analysis of marker structural bands of the polyesters revealed structural changes in the host which mainly affect the ester groups, most probably due to a restructuring of the polyester chain to better accommodate the ligand. Copyright © 2010 John Wiley & Sons, Ltd.
Surface‐enhanced Raman scattering study of Ag@PPy nanoparticles
Authors: Ye Sunjie , Fang Li , Qing Xutang , Lu Yun
Published: January 2010

Surface‐enhanced Raman scattering (SERS) spectra of Ag@polypyrrole (PPy) nanoparticles with both 488 and 1064 nm excitation were investigated. Experimental results as well as theoretical analysis demonstrated that electromagnetic (EM) enhancement and charge transfer (CT) both rebounded to the SERS effect of Ag@PPy nanoparticles. When near‐IR excitation (1064 nm) was used for the SERS measurements, the contribution from CT was amplified relative to that from EM because the energy of the near‐IR excitation is far from the surface plasmon resonance of the nanosized Ag particles. The increased doping level of PPy, leading to optimal energy matching between the Fermi levels of the Ag nanoparticles and the energy levels in PPy molecules, could obviouslyenhance the SERS signal. These results suggested that the SERStechnique wasan effective tool for investigating the doping effect and interface interaction in metal‐conductingpolymer composite nanoparticles. In particular, the SERS technique with near‐IR excitation could give more information regarding the contribution of the charge‐transfer mechanism to the spectral enhancement of this kind of system. Copyright © 2010 John Wiley & Sons, Ltd.
Resonance Raman intensity analysisof the excited‐state photochemical dynamicsof dimethyl 1,3‐dithiole‐2‐thione‐4,5‐dicarboxylate in the A‐band absorption
Authors: Liu Bo , Wu Bin , Xu Jun , Wu Zhangzhu , Zhao Yanying , Zheng Xuming , Wang Huigang
Published: January 2010

Dimethyl 1,3‐dithiole‐2‐thione‐4,5‐dicarboxylate (DDTD) was synthesized and characterized using NMR, Fourier transform (FT)‐Raman, Fourier transform‐infrared (FT‐IR) and UV spectroscopies. Resonance Raman spectra (RRs) were obtained with 341.5, 354.7 and 368.9 nm excitation wavelengths and density functional calculations were carried out to elucidate the π (SCS) →π* (SCS) electronic transitions and the RRs of DDTD in cyclohexane solution. The RRs indicate that the Franck–Condon region photo dynamics have a multidimensional character with motion predominantly along the CS stretch and the CS symmetric stretch modes in the five‐member heterocycle. A preliminary resonance Raman intensity analysis was carried out and the results for DDTD were compared with previously reported results for 1,3‐dithiole‐2‐thione (DTT). Differences and similarities of the spectra in terms of molecular symmetry and electron density are also discussed. Copyright © 2010 John Wiley & Sons, Ltd.
Experimental study of the Raman strain rosette based on the carbon nanotube strain sensor
Authors: Qiu Wei , Kang Yi‐Lan , Lei Zhen‐Kun , Qin Qing‐Hua , Li Qiu , Wang Quan
Published: January 2010

This work presents a new technique named Raman strain rosette for the micro‐strain measurement of both Raman active and Raman inactive materials. The technique is based on the theoretical model of the carbon nanotube (CNT) strain sensor that applies the resonance and polarization Raman properties of CNTs and calculates the synthetic contributions of uniformly dispersed CNTs to the entire Raman spectrum. In our work, the proposed technique is applied in different experiments on the Raman inactive materials, such as step‐by‐step uniaxial tensile and Raman mapping around a circular hole. The experimental results reached by the Raman strain rosette are consistent with the actual values as a whole. This study verifies that the Raman strain rosette is applicable to quantitative measurement of all the in‐plane components of the strain tensor (including both normal and shear strains) by three polarized Raman detections for each sampling spot on a microscale. The technique is further applicable to achieving the strain fields through Raman mapping. Copyright © 2010 John Wiley & Sons, Ltd.
Photonic nanoarchitectures in butterflies and beetles: valuable sources for bioinspiration
Authors: Biró L.P. , Vigneron J.P.
Published: January 2010

Nature began developing photonic nanoarchitectures millions of years before humankind. Often, in the living world, color is a communication channel that may influence the chance of the individual surviving as well as the chance to reproduce. Therefore, natural color‐generating structures are highly optimized by many millennia of evolution. In this review, a survey is presented of the development of natural photonic crystal‐type nanoarchitectures occurring in butterflies and beetles from the standpoint of physics and materials science, covering the past ten years. One‐, two‐, and three‐dimensional structures are reviewed, emphasizing the role that disorder, or irregularity, may play in natural nanoarchitectures to achieve certain visual effects. The characterization, modeling methods, and rapidly growing number of bioinspired or biomimetic applications are discussed.
Stabilized lasers for advanced gravitational wave detectors
Authors: Willke B.
Published: January 2010

Second‐generation interferometric gravitational wave detectors require high‐power lasers with approximately 200 W of output power in a linear polarized, single‐frequency, fundamental‐mode laser beam. Furthermore very high temporal and spatial stability is required. This paper discusses the design of a 200 W pre‐stabilized laser (PSL) system and the underlying concepts. The PSL requirements for advanced gravitational wave detectors as well as for the laser system are described. The laser stabilization scheme proposed for the Advanced LIGO gravitational wave detector and the so‐called diagnostic breadboard will serve as examples to explain the general laser stabilization concepts and the achieved performance and its limitations.
Poly(N,N‐dimethylacrylamide)‐block‐Poly(L‐lysine) Hybrid Block Copolymers: Synthesis and Aqueous Solution Characterization
Authors: Triftaridou Aggeliki I. , Chécot Frédéric , Iliopoulos Ilias
Published: January 2010

Four poly(N,N‐dimethylacrylamide)‐block‐poly(L‐lysine) (PDMAM‐block‐PLL) hybrid diblock copolymers and two PLL homo‐polypeptides are prepared via ROP of ε‐trifluoroacetyl‐L‐lysine N‐carboxyanhydride initiated by primary amino‐terminated PDMAM and n‐hexylamine respectively. The PLL blocks render the copolymers a multi‐responsive behavior in aqueous solution due to their conformational transitions from random coil to α‐helix with increasing pH, and from α‐helix to β‐sheet upon heating. The random coil‐to‐α‐helix transition is found to depend on the PLL length: the longer the peptide segment, the more readily the transition occurred. The same trend was observed for the α‐helix‐to‐β‐sheet transition, which was found to be inhibited for short polypeptides unless conjugated with the PDMAM block.

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Enhanced Properties of Dissimilar Rubber Blends Using Microencapsulated Sulfur Through Acetylene Plasma Polymerization
Authors: Guo Rui , Talma Auke G. , Datta Rabin N. , Dierkes Wilma K. , Noordermeer Jacques W. M.
Published: January 2010

Surface modification of sulfur by vacuum plasma polymerization with acetylene was applied in order to modify its surface properties without losing reactivity for vulcanization. A nm‐thin layer of crosslinked polyacetylene was deposited on the surface of the sulfur powder. Its surface energy was decreased as monitored by wetting in liquids of various polarities. A delay in the onset of weight loss by sublimation in thermal gravimetric analysis was shown by the plasma‐modified sulfur. Scanning electron microscopy showed a core/shell structure of the coated sulfur. In 50:50 blends of styrene‐butadiene rubber and ethylene‐propylene‐diene rubber, the encapsulated sulfur samples resulted in pronounced improvements in the mechanical properties relative to the use of unmodified sulfur.

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Collagen Cryogel Cross‐Linked by Dialdehyde Starch
Authors: Mu Changdao , Liu Fang , Cheng Qingsu , Li Hongli , Wu Bo , Zhang Guangzhao , Lin Wei
Published: January 2010

A 3D spongy collagen cryogel was prepared using DAS as the cross‐linker. FTIR and CD studies demonstrate that crosslinking is achieved through the reaction of the DAS aldehyde groups with the free amino groups in collagen without affecting the triple helix of collagen. SEM demonstrates that the cryogel has a heteroporous structure with interconnecting pores. DSC measurements reveal that the cryogels have improved thermal stability in comparison with pure collagen. Moreover, the ESR shows that the water uptake of the cryogel decreases with DAS content. Evaporation tests indicate that the cryogel can hold moisture for a long time. Since both collagen and DAS are nontoxic and the resultant cryogel is blood‐compatible, the cryogel is expected to be useful, e.g., as wound dressing.

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The Advantages of In Situ Surfactant Generation for Miniemulsions
Authors: El‐Jaby Ula , Cunningham Michael , McKenna Timothy F. L.
Published: January 2010

The stabilisation of miniemulsions using an in situ generated surfactant is presented. This surfactant, prepared from of a water‐soluble base and an oil‐soluble long chain acid was successfully used to create stable miniemulsions with up to 60 vol.‐% organic phase. It is shown that the creation of a surface active species at the oil–water interface allowed stable miniemulsions to be generated more rapidly than when using conventional surfactant. In addition, polymerised miniemulsions exhibited less secondary nucleation when in situ surfactants were used.

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Investigation of Cationic Polymerization of β‐Pinene Using Calorimetric Measurements
Authors: Poço João Guilherme Rocha , Danese Modesto , Giudici Reinaldo
Published: January 2010

An experimental investigation of the kinetics of cationic polymerization of β‐pinene was performed using two different initiator systems under two different operating conditions (shot additions of initiator, and continuous feeding of monomer). The experiments were done using calorimetric measurements under isoperibolic conditions. The heat of polymerization of β‐pinene was found to be −30.6 kcal · mol−1. A simple kinetic model was tentatively proposed, and the model fit reasonably well to the different experimental runs. Different values of the fitting parameters were obtained for runs carried out under different conditions, which can probably be ascribed to the presence of adventitious impurities in the commercial‐grade monomer used.

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Kinetic Study of Ethylene Homopolymerization in Slurry Using a Ziegler‐Natta Catalyst
Authors: Gemoets Frederik , Zhang Min , Karjala Thomas W. , Kolthammer Brian W. S.
Published: January 2010

The kinetic behavior of a Ziegler‐Natta catalyst at 86 °C under homopolymerization conditions in a continuous slurry polymerization reactor is studied. The effects of ethylene and hydrogen concentrations on the polymerization rate and polymer properties such as $\overline M _{\rm n}$ and $\overline M _{\rm w}$ were investigated. A kinetic model based on two catalytic lumped sites was developed to predict polymerization rate and $\overline M _{\rm n}$ and $\overline M _{\rm w}$ from reactor operating conditions. Each lumped site is assumed to be activated instantaneously. Such activation either is spontaneous or requires an ethylene molecule. The model has high fidelity in predicting experimental observations using kinetic parameters estimated from the experimental data and is used for industrial process development, optimization, and new product development.

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Functionalization of Polymer Nanoparticles Formed by Microemulsion RAFT‐Mediated Polymerization
Authors: Pascual Sagrario , Urbani Carl N. , Monteiro Michael J.
Published: January 2010

Polymer nanoparticles were prepared via a microemulsion RAFT polymerization using a xanthate chain transfer agent. The xanthate moiety at the polymer chain‐end preferentially resides at the polymer/water interface. This allows not only the formation of block copolymers to be synthesized in water but also further functionalization of the nanoparticle surface with other macromolecules. The synthesis of polystyrene latex nanoparticles by xanthate‐mediated microemulsion polymerization is described. The resulting nanoparticles had an average hydrodynamic diameter of 25 nm and a narrow particle size distribution, with PNIPAM being bound to the surface. Our novel method of functionalized polymer nanoparticles can be used for the coupling of important biomacromolecules.

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Study of Burn Rate Suppressants in AP‐Based Composite Propellants
Authors: Ghorpade Vishwas Govindrao , Dey Abhijit , Jawale Lalita Sudhir , Kotbagi Amarnath Madiwal , Kumar Arvind , Gupta Manoj
Published: January 2010

A number of composite propellant compositions based on various burn rate suppressants were formulated and studied with the aim to select a suitable burn rate suppressant for reducing the burn rate of the basic propellant composition. Theoretical properties of the compositions were computed by using NASA CEC‐71 program and the burn rate performance was evaluated. In addition, sensitivity, thermal, and mechanical properties of the compositions were also evaluated. The composition containing 60% AP, 10% Al, 20% binder, and 10% burn rate suppressant (melamine) was insensitive to friction and impact (28.8 kg and 0.56 m) and showed 90% weight loss. The formulation was found to be relatively superior.
A comprehensive examination of the contributions to the binding entropy of protein–ligand complexes
Authors: Singh Nidhi , Warshel Arieh
Published: January 2010

One of the most important requirements in computer‐aided drug design is the ability to reliably evaluate the binding free energies. However, the process of ligand binding is very complex because of the intricacy of the interrelated processes that are difficult to predict and quantify. In fact, the deeper understanding of the origin of the observed binding free energies requires the ability to decompose these free energies to their contributions from different interactions. Furthermore, it is important to evaluate the relative entropic and enthalpic contributions to the overall free energy. Such an evaluation is useful for assessing temperature effects and exploring specialized options in enzyme design. Unfortunately, calculations of binding entropies have been much more challenging than calculations of binding free energies. This work is probably the first to present microscopic evaluation of all of the relevant components to the binding entropy, namely configurational, polar solvation, and hydrophobic entropies. All of these contributions are evaluated by the restraint release approach. The calculated results shed an interesting light on major compensation effects in both the solvation and hydrophobic effect and, despite some overestimate, can provide very useful insight. This study also helps in analyzing some problems with the widely used molecular mechanics/Poisson‐Boltzmann surface area approach. Proteins 2010. © 2010 Wiley‐Liss, Inc.
Interpretation and consequences of Meyer–Neldel rule for conductivity of phase change alloys
Authors: Savransky S. D. , Yelon A.
Published: January 2010

Measurements of conductivity as a function of temperature were performed on a large number of memory cells of a GeSbTe phase change memory alloy, in both the set and reset states. Conductivity obeys the Meyer–Neldel rule in both states, with the same Meyer–Neldel, or isokinetic, temperature, but with conductivity prefactors about six orders of magnitude larger in the set than in the reset state. These observations are interpreted in terms of the multiexcitation entropy model, and conduction mechanisms are suggested. Their effect on the expected behavior of memories is considered.
High‐forward‐bias transport mechanism in a‐Si:H/c‐Si heterojunction solar cells
Authors: Schulze T. F. , Korte L. , Conrad E. , Schmidt M. , Rech B.
Published: January 2010

In order to elucidate the transport mechanism in a‐Si:H/c‐Si heterojunction solar cells under high forward bias (U > 0.5 V), we conducted temperature‐dependent measurements of current–voltage (I–V) curves in the dark and under illumination. ZnO:Al/(p)a‐Si:H/(n)c‐Si/(n+)a‐Si:H cells are compared with inversely doped structures and the impact of thin undoped a‐Si:H buffer layers on charge carrier transport is explored. The solar cell I–V curves are analyzed employing a generalized two‐diode model which allows fitting I–V data for a broad range of samples. The fitting results are complemented with numerical simulations using AFORS‐HET under consideration of microscopic a‐Si:H parameters as determined by constant‐final‐state‐yield photoelectron spectroscopy (CFSYS) to identify possible origins for a systematic increase of the high‐forward‐bias ideality factor along with the open‐circuit voltage (Voc). It is further shown that also for a‐Si:H/c‐Si heterojunctions, dark I–V curve fit parameters can unequivocally be linked to Voc under illumination, which may prove helpful for device assessment.
75As NMR relaxation in glassy Ge–As–Se
Authors: Mammadov Eldar , Taylor P. Craig , Reyes Arneil , Mehdiyeva Salima , Kuhns Phillip
Published: January 2010

We have used high magnetic fields to perform 75As nuclear magnetic resonance (NMR) relaxation measurements in Ge–As–Se glasses. The spin–lattice relaxation time T1 has been studied as a function of average coordination number, 〈r〉 and temperature, T. We show that the relaxation time constant, T1, in this system can be a useful tool to probe rigidity of the glassy matrix. In the two extreme cases, zero‐field nuclear quadrupole resonance (NQR) and high‐field NMR, T1 exhibits a similar dependence on the average coordination number. Namely, there is a region in this dependence at low 〈r〉 values, where the spin–lattice relaxation time does not change remarkably, followed by an increase in T1 in glasses with 〈r〉 more than 2.54. This transition can be correlated with the onset of rigidity percolation in the glassy matrix. The temperature dependence of the spin–lattice relaxation rate is found in the form T ∝ T2. This behavior is typical for As and other nuclei in glasses at temperatures below 300 K and is indicative of Raman‐like relaxation mechanism involving low‐frequency modes. Spin‐echo intensity for Ge2As2Se5 as a function of pulse separation exhibits exponential decay whose slope is the same as one of the average of the decay found from 75As NQR measurements. This result indicates to the presence of indirect dipolar coupling of arsenic atoms in this composition.
Passivation study of the amorphous–crystalline silicon interface formed using DC saddle‐field glow discharge
Authors: Bahardoust Barzin , Chutinan Alongkarn , Leong Keith , Gougam Adel B. , Yeghikyan Davit , Kosteski Tome , Kherani Nazir P. , Zukotynski Stefan
Published: January 2010

The DC saddle‐field (DCSF) glow discharge method was used to deposit intrinsic a‐Si:H onto c‐Si to passivate the c‐Si surface. The effective minority carrier lifetime in the heterostructures as a function of the excess minority carrier density in the c‐Si wafers was measured. The results were then analyzed in the context of recombination associated with interface defect states using three known recombination models. The defect density and the charge density at the interface are inferred. In addition subsequent annealing of the samples was studied. It is shown that for our intrinsic a‐Si:H samples improvements in surface passivation are directly correlated with the reduction of interface defects and not the reduction of minority carrier concentration at the interface due to electric field. We have achieved excellent surface passivation with effective carrier lifetime >4 ms for an intrinsic a‐Si:H sample deposited at a process temperature of 200 °C and thickness of about 30 nm. It is also demonstrated that subsequent annealing, at 240 °C, of the samples which were prepared at process temperatures <240 °C greatly increases the effective lifetime.
High efficiency amorphous and nanocrystalline silicon solar cells
Authors: Yan Baojie , Yue Guozhen , Xu Xixiang , Yang Jeffrey , Guha Subhendu
Published: January 2010

This paper reviews our progress of using nc‐Si:H as a low bandgap absorber material to substitute for a‐SiGe:H alloys in multi‐junction solar cells. We have focused on three topics: (1) high deposition rate, (2) large area uniformity of thickness and material properties, (3) high solar cell and module efficiencies. Initially, we investigated various deposition methods, including RF, VHF, and microwave glow discharges. After several years of systematic studies, we have been convinced that VHF glow discharge is an applicable method to attain high rate and large‐area uniform nc‐Si:H depositions. We also studied the stability of nc‐Si:H solar cells and observed various metastability phenomena in nc‐Si:H solar cells. We have reported an initial active‐area cell efficiency of 15.4% using an a‐Si:H/a‐SiGe:H/nc‐Si:H triple‐junction structure. Subsequently, we have increased the deposition rates to around 1.0–1.5 nm/s and achieved an initial active‐area efficiency of 13.4% using an a‐Si:H/nc‐Si:H/nc‐Si:H triple‐junction structure. Recently, a stable total‐area efficiency of 12.5% was measured at NREL on our a‐Si:H/nc‐Si:H/nc‐Si:H triple‐junction solar cell. We have also developed large‐area VHF deposition systems and demonstrated encouraging module efficiencies using a‐Si:H/nc‐Si:H/nc‐Si:H triple‐junction structures. Initial and stable aperture‐area (400 cm2) efficiencies of 11.0 and 10.1% have been achieved with fully encapsulated modules with a‐Si:H/nc‐Si:H/nc‐Si:H triple‐junction structures. In this paper, various aspects of nc‐Si:H solar cells are discussed, including the material structures, device design, light trapping, metastability, high efficiency solar cell optimization, and large‐area deposition.
Hydrogen atom abstraction reactions of the sugar moiety of 2′‐deoxyguanosine with an OH radical: A quantum chemical study
Authors: Shukla P. K. , Kumar N. , Mishra P. C.
Published: January 2010

Mechanisms of hydrogen atom abstraction reactions of the sugar moiety of 2′‐deoxyguanosine with an OH radical were investigated using the B3LYP and BHandHLYP functionals of density functional theory and the second order Møller–Plesset Perturbation (MP2) theory in gas phase and aqueous media. The 6‐31+G* and AUG‐cc‐pVDZ basis sets were used. Gibbs free barrier energies and rate constants of the reactions in aqueous media suggest that an OH radical would abstract the hydrogen atoms of the sugar moiety of 2′‐deoxyguanosine in the following order of preference: H5′ ≈ H5″ > H3′ > H4′ > H1′ ≈ H2′ > H2″, the rate constant for H5′ abstraction being 103–105 times greater than that for H2″ at the different levels of theory. Relative stabilities of the different deoxyribose radicals are also discussed. The most and least favored hydrogen abstraction reactions found here are in agreement with experimental observation. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
An ONIOM and DFT study of water and ammonia adsorption on anatase TiO2 (001) cluster
Authors: Erdogan Rezan , Onal Isik
Published: January 2010

Density functional theory (DFT) calculations at ONIOM DFT B3LYP/ 6‐31G**‐MD/UFF level are employed to study molecular and dissociative water and ammonia adsorption on anatase TiO2 (001) surface represented by partially relaxed Ti20O35 ONIOM cluster. DFT calculations indicate that water molecule is dissociated on anatase TiO2 (001) surface by a nonactivated process with an exothermic relative energy difference of 58.12 kcal/mol. Dissociation of ammonia molecule on the same surface is energetically more favorable than molecular adsorption of ammonia (−37.17 kcal/mol vs. −23.28 kcal/mol). The vibration frequency values also are computed for the optimized geometries of adsorbed water and ammonia molecules on anatase TiO2 (001) surface. The computed adsorption energy and vibration frequency values are comparable with the values reported in the literature. Finally, several thermodynamical properties (ΔH°, ΔS°, and ΔG°) are calculated for temperatures corresponding to the experimental studies. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Combined experimental and computational modeling studies on 4‐[(2‐hydroxy‐3‐methylbenzylidene) amino]‐1,5‐dimethyl‐2‐phenyl‐1,2‐dihydro‐3H‐pyrazol‐3‐one
Authors: Tanak Hasan , Ağar Ayşen , Yavuz Metin
Published: January 2010

The Schiff base compound, 4‐[(2‐hydroxy‐3‐methylbenzylidene)amino]‐1,5‐dimethyl‐2‐phenyl‐1,2‐dihydro‐3H‐pyrazol‐3‐one, has been synthesized and characterized by IR, UV–vis, and X‐ray single‐crystal determination. Molecular geometry from X‐ray experiment of the title compound in the ground state have been compared using the density functional method (B3LYP) with 6‐31G(d,p) basis set. Calculated results show that density functional theory (DFT) can well reproduce the structure of the title compound. The energetic behavior of the title compound in solvent media has been examined using B3LYP method with the 6‐31G(d,p) basis set by applying the Onsager and the polarizable continuum model (PCM). The results obtained with these methods reveal that the PCM method provided more stable structure than Onsager's method. By using TD‐DFT method, electronic absorption spectra of the title compound have been predicted and a good agreement with the TD‐DFT method and the experimental one is determined. The predicted nonlinear optical properties of the title compound are much greater than ones of urea. In addition, DFT calculations of the title compound, molecular electrostatic potential and NBO analysis were performed at B3LYP/6‐31G(d,p) level of theory. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
A perturbation theory without energy corrections
Authors: Dhatt S. , Bhattacharyya K.
Published: January 2010

We employ logarithmic perturbation theory in a form that utilizes the force, instead of the potential, and yields equations for wavefunction‐correction terms without requiring any information of energy corrections at any stage. The knowledge of unperturbed eigenfunctions of other states is also unnecessary. The perturbed energy eigenvalue can be obtained as a series either by going back to the parent equation, or as an average value involving the perturbed state. The latter scheme applies to any other average property as well. Both ground and excited states of a few systems are chosen for demonstrative calculations. Influence of the nodal structure on the exponential function controlling spatial behavior of the probability density is discussed. Interrelations among specific correction terms are shown in the small‐ and large‐x regime; in the latter case, certain terms nicely sum up to yield the correct decay characteristics of the probability density as well. Relevance of the basic equation to an alternative, nonperturbative scheme of approximation is also outlined. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Human cytomegalovirus tropism for endothelial/epithelial cells: scientific background and clinical implications
Authors: Revello M. Grazia , Gerna Giuseppe
Published: January 2010

Human cytomegalovirus (HCMV) has been routinely isolated from and propagated in vitro in human embryonic lung fibroblast (HELF) cell cultures, while in vivo it is known to infect predominantly endothelial and epithelial cells. In recent years, genetic determinants of the HCMV tropism for endothelial/epithelial cells were identified in the UL131A/UL130/UL128 locus of HCMV genome of wild‐type strains. UL131A‐UL128 gene products form a complex with glycoprotein H (gH) and L (gL) resulting in a gH/gL/UL131A‐UL128 complex that is required for HCMV entry into endothelial/epithelial cells. In contrast, virus entry into fibroblasts has its genetic determinants in the complex gH/gL/gO (or gH/gL). During primary HCMV infection, the neutralising antibody response measured in endothelial cells (EC) is potent, occurs very early and is directed mostly against combinations of two or three gene products of the UL131A‐128 locus. On the contrary, neutralising antibodies measured in fibroblasts appear late, are relatively weak in potency and are directed against gH and gB. The T‐cell immune response to UL131A‐UL128 gene products remains to be investigated. Recently, a role has been proposed for neutralising antibody in conferring prevention/protection against HCMV infection/disease in pregnant women with primary HCMV infection. However, the level of cooperation between humoral immunity and the well‐established T‐cell protection remains to be defined. Copyright © 2010 John Wiley & Sons, Ltd.