bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and Optical Properties of Soluble Polyimide/Titania Hybrid Thin Films
Authors: Chang Chih‐Ming , Chang Cheng‐Liang , Chang Chao‐Ching
Published: November 2006

Summary: In this study high‐refractive‐index polyimide/titania hybrid optical thin films were successfully prepared using a sol‐gel process combined with spin coating and multistep baking. The hybrid thin films were prepared from a soluble polyimide, a coupling agent, and a titania precursor. Transparent hybrid thin films can be obtained at TiO2 content as high as 40 wt.‐%. The FE‐SEM results suggest that the TiO2 particles in the hybrid thin films have diameters in the nanometer range. The thermal decomposition temperatures of the prepared hybrid materials are above those of the respective polyimide except for the highest TiO2 content hybrids. The refractive indices at 633 nm of the prepared hybrid thin films increase linearly from 1.66 to 1.82 with increasing TiO2 content. The excellent optical transparency, thermal stability, and tunable refractive index provide the potentials of the polyimide/titania hybrid thin films in optical applications.

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Modulation of lung cancer growth arrest and apoptosis by Phellinus Linteus
Authors: Guo Jinjin , Zhu Tongbo , Collins LeaAnn , Xiao Zhi‐Xiong J. , Kim Sung‐Hoon , Chen Chang‐Yan
Published: November 2006

The Phellinus Linteus (PL) mushroom has been shown to possess anti‐tumor properties. Through influencing lymphocytes, PL indirectly augments the host's immune system against cancer cells. PL has also been demonstrated to reduce tumor proliferation. However, the mechanisms of PL against malignant growth have not yet been fully explored. In this study, we report that PL mediates the following two activities in mouse and human lung cancer cells: cell‐cycle arrest at a low concentration of PL and apoptosis in response to a high dose of PL. After exposure to a low dose of PL, G1 growth arrest occurred in the lung cancer cells. The negative growth control mediated by PL is evidenced by the decrease of the activities of cyclin‐dependent kinases CDK2, 4, and 6. In contrast, at high doses, PL‐induced lung cancer cells to undergo apoptosis in a dose‐dependent fashion. This was evidenced by DNA fragmentation, caspase activation, and loss of clonogenecity in the lung cancer cells, all of which were lacking in the lung cancer cells treated with low concentrations of PL as well as the normal mouse lung epithelial cells exposed to either low or high concentrations of PL. The addition of the caspase inhibitor Z‐VADfmk completely suppressed PL‐induced apoptosis. Furthermore, the low dose of PL was able to synergize with doxorubicin to induce apoptosis in the lung cancer cells. Thus, our findings suggest that PL regulates two responses in the lung cancer cells: cell‐cycle arrest and apoptosis. © 2006 Wiley‐Liss, Inc.
Dynamin 2 associates with complexins and is found in the acrosomal region of mammalian sperm
Authors: Zhao Longmei , Shi Xudong , Li Lingjun , Miller David J.
Published: November 2006

Previous data showed that complexin I, a SNARE regulatory protein, is localized in and/or around the acrosome and is necessary for the acrosome reaction in sperm. To understand how complexin I regulates the acrosome reaction, we used complexin‐GST pulldown assays to identify interacting proteins. We showed that both complexins I and II bound mouse sperm dynamin 2. Dynamin 2 is a 100 kDa GTPase essential to many aspects of endocytosis but its potential role in exocytosis is unknown. Dynamin 2 is expressed in rat testis and widely expressed in other tissues; however, the function of dynamin 2 in germ cells is uncertain. Dynamin 2 protein was detected in mouse testis and was most abundant in or around the developing acrosome of spermatids. In addition, dynamin 2 was co‐localized with complexin I in the acrosomal region of mammalian sperm. Its co‐localization and interaction with complexin I suggest that dynamin 2 may play a role during acrosome formation and/or acrosomal exocytosis. Mol. Reprod. Dev. 74: 750–757, 2007. © 2006 Wiley‐Liss, Inc.
Using the histone H2a transcript as an endogenous standard to study relative transcript abundance during bovine early development
Authors: Vigneault Christian , Gilbert Isabelle , Sirard Marc‐André , Robert Claude
Published: November 2006

The requirement for sample standardization is basic to any relative RNA abundance assessment. In 2002, we published on the RNA abundance profiling of several housekeeping targets during early bovine embryonic development. It was then concluded that histone H2a was the most stable transcript across the studied developmental period. Since that time, several teams have applied this information, yet neglected to use the published set of primers. Here, we show that these other primer sets do not target the same histone H2a variant. Within the present report, the RNA abundance profiles of their respective targets, for example, histone H2a.1, H2a.z, and H2a.o were measured in developmental series spanning the immature oocyte to the blastocyst stage embryo. In order to more clearly define the conditions that impact the RNA abundance level measurement of these candidates, the state of polyadenylation and the origin of the transcript either from de novo transcription or from maternal stocks were taken into consideration. The histone H2a.z transcript is principally regulated by de novo transcription following embryonic genome activation, whereas the levels of H2a.1 and H2a.o variants are largely of maternal origin, conferring a more stable profile throughout the studied developmental window. The histone H2a.z was found solely in a polyadenylated state whereas the H2a.1 and H2a.o were found to be more abundant in a nonadenylated form. The presence of serum in the in vitro embryo production system also had some impact on the histone H2a.1 RNA level at the blastocyst stage. Mol. Reprod. Dev. 74: 703–715, 2007. © 2006 Wiley‐Liss, Inc.
Comparison of global gene expression between porcine testis tissue xenografts and porcine testis in situ
Authors: Zeng Wenxian , Rathi Rahul , Pan Hua , Dobrinski Ina
Published: November 2006

Testis tissue from immature mammalian donor animals, grafted ectopically to immunodeficient mouse hosts, can undergo complete spermatogenesis with the production of fertilization‐competent spermatozoa. To further characterize testis tissue xenografts as a model for testis function in situ, the objective of this study was to compare gene expression between porcine testis tissue xenografts and testis tissue in situ. Pieces of testis tissue from 1‐week‐old piglets were grafted onto immunodeficient male mice and a littermate piglet was raised for comparison as control. Complete spermatogenesis was present in the testis tissue xenografts at 8 months after transplantation into mouse hosts and in the 8‐month‐old control porcine testis tissue. Total RNA was isolated from xenografts and control tissue, and the RNA was labeled and hybridized to the porcine genome array. By analyzing the expression of 23,256 transcripts, we found that 71 genes were differentially expressed with at least a fourfold difference between xenografts and control tissue. Interestingly, none of the 56 transcripts present on the array that were annotated in porcine testis showed differential expression between xenografts and control testis. This analysis indicates that global gene expression in porcine testis xenografts appears comparable to testis tissue in situ. These findings support the hypothesis that testis tissue xenografts can provide a representative model to study mammalian spermatogenesis. Mol. Reprod. Dev. 74: 674–679, 2007. © 2006 Wiley‐Liss, Inc.
Improving the performance of the boundary element method with time‐dependent fundamental solutions by the use of a wavelet expansion in the time domain
Authors: Barmada Sami
Published: November 2006

The object of this paper is a wavelet‐based formulation of the boundary element method (BEM) for diffusion problems, characterized by time‐dependent fundamental solution. While the BEM is a well known and often used technique, its time‐dependent formulation for diffusion problems is very rarely used in practical applications, due to the high computational cost which characterizes it. Here, a new formulation is proposed, which, through the use of the wavelet expansion of the time behaviour of the boundary elements, is characterized by a lower CPU time consumption when compared with the standard BEM diffusion formulation. The problem to be solved is transformed into an algebraic system (of higher dimension) and its solution gives the time domain behaviour of the desired quantities; in this way, the time stepping procedure is avoided. Together with the formulation, the analysis of the computational cost, and two examples are given in the paper. Copyright © 2006 John Wiley & Sons, Ltd.
Indigenous innovators: the role of web marketing for cultural micro‐enterprises
Authors: Cardamone Megan , Rentschler Ruth
Published: November 2006

The Indigenous cultural sector is a dynamic and highly valuable to the Australian economy, returning an estimated $100 million annually. The majority of Indigenous cultural producers are micro‐enterprises—businesses consisting of fewer than five employees. Many of these struggle to market their products, some from extremely remote and isolated locations; others with few resources in urban areas.

This paper initially approaches a conceptual orientation to Web marketing as a potential signifier of innovation and entrepreneurship. The paper draws on previous literature and a current exploratory study of Indigenous Cultural Micro‐Enterprises (ICMEs), focussing on two case studies for deeper analysis. The two exemplary cases outlined are Maningrida Arts Centre, and the performing arts organisation Kooemba Jdarra. Specifically, their innovative use of recent technology (multimedia websites) will be assessed to answer the question: What are the attributes of effective ICME Web marketing?

Copyright © 2006 John Wiley & Sons, Ltd.
Fluoropolymers in automotive applications
Authors: Drobny Jiri George
Published: November 2006

Fluoropolymers, in the form of thermoplastics and elastomers, find a wide use in automotive applications, because of the combination of their high resistance to fuels, lubricants and to elevated temperatures. Examples are fuel and vapor management hoses, fuel tank filler necks, wire insulations, O‐rings, diaphragms, seals, etc. This contribution covers the basic chemistry of fluoropolymers used in the automotive industry, their properties and specifics about the main automotive applications. Copyright © 2006 John Wiley & Sons, Ltd.
Modification of mesostructure base on composition of silica materials and their applications to pH sensing
Authors: Kang Eun‐Hee , Shim Jong‐Min , Kang Hyo‐Jin , Park Sang‐Wook , Lee Jae‐Wook , Lee Jin Kook
Published: November 2006

This study induced a chemical combination of fluoresceinamine (FA) and (3‐chloropropyl)triethoxysilane (CP‐TEOS) in the presence of tetraethyl orthosilicate (TEOS) which is able to maintain the shape of the mesostructure without prior removal of the surfactant. The sol‐gel derived silica films were controlled by the reaction time and molar ratios of TEOS and CP‐TEOS, and characterized in terms of response to pH, pKa values, effects of oxidation number, leaching, and scanning electron microscopy (SEM) imaging. The conclusions include the effect on molar ratios and the choice of reaction time. The results of this study are summarized as follows: (1) increasing the molar ratio of TEOS, the mesostructure of these films exhibited not only perfect single‐crystal morphology but also a hexagonal morphology; (2) the most suitable molar ration in this synthesis is the ratio of 1:1 (the molar ratio of TEOS and CP‐TEOS); (3) the reaction time for this system should be controlled at least to over 6 hr in order to maintain high intensity absorbance against a minimum of indicator quantity. Leaching‐out is more pronounced for films used directly after preparation and varies for different molar ratios. The long‐term implication of leaching‐out on sol‐gel based pH sensors is discussed. Copyright © 2006 John Wiley & Sons, Ltd.
The C allele of the GNB3 C825T polymorphism of the G protein β3‐subunit is associated with an increased risk for the development of oncocytic thyroid tumours
Authors: Sheu S‐Y , Handke S , Bröcker‐Preuss M , Görges R , Frey UH , Ensinger C , Öfner D , Farid NR , Siffert W , Schmid KW
Published: November 2006

Carriers of the C allele of the common C825T polymorphism in the GNB3 gene of the G protein have been associated with the development of follicular thyroid adenomas. Since the C allele of this polymorphism is related to a lower signalling capacity, it was speculated whether the C825T polymorphism may play a particular role in oncocytic thyroid tumours, which are recognized for their reduced ability to synthesize thyroid‐specific proteins and hormones, although they possess an intact thyroid‐stimulating hormone receptor–adenylyl cyclase system. Using pyrosequencing, both the genotype distribution and the allele frequency of the C825T polymorphism were investigated in a series of 104 patients with oncocytic thyroid tumours of follicular cell origin [58 adenomas, 41 follicular thyroid carcinomas (FTCs), and five papillary thyroid carcinomas (PTCs)]; the results were compared with those obtained from 321 age and gender‐matched healthy blood donors and a series of 327 non‐oncocytic thyroid tumours of follicular cell origin (119 adenomas, 80 FTCs, and 186 PTCs). Analysis of the genotype distribution (comparing oncocytic with non‐oncocytic tumours of the present series) revealed a significantly increased odds ratio (OR) for CC versus TT (OR = 4.22; p = 0.011) and CC versus CT (OR = 1.62; p = 0.049) carriers to develop an oncocytic thyroid tumour; ORs to develop an oncocytic thyroid tumour were also increased comparing the genotype distribution between the group of oncocytic tumours and healthy controls for CC versus TT (OR = 3.73; p = 0.017) and CC versus all T carriers (OR = 1.56; p = 0.034). Oncocytic thyroid tumours as a group showed a statistically significant increase of the C‐allele frequency when compared with all non‐oncocytic tumours (p = 0.0039) as well as healthy blood donors (p = 0.017). The results strongly suggest that the C allele of the GNB3 C825T polymorphism of the G protein β3‐subunit is associated with an increased risk for the development of oncocytic thyroid tumours. This polymorphism may thus be considered a (co)factor favouring the development of oncocytic thyroid tumours, although the biological mechanism(s) underlying this association remain obscure. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Triaminotriazines—photophysical investigations of a porphyrin‐appended triazine receptor with a naphthalene diimide guest
Authors: Ghiggino Kenneth P. , Hutchison James A. , Langford Steven J. , Latter Melissa J. , Takezaki Makoto
Published: November 2006

A modular synthetic approach to preparing a family of triaminotriazine receptors bearing porphyrin chromophores is described. The porphyrin‐appended triaminotriazines are prepared in a stepwise manner employing either cyanuric chloride or fluoride and 5‐(4′‐aminophenyl)‐10,15,20‐triphenylporphyrin in the first step. Reaction of the porphyrintriazine with excess 1‐pentylamine leads to a triazine core programmed for three‐point hydrogen bonding. Addition of a complementary naphthalene diimide yields a supramolecular donor–acceptor dyad. Photophysical studies in CH2Cl2 solvent show efficient quenching of porphyrin fluorescence within the dyad, consistent with an electron transfer process. Copyright © 2006 John Wiley & Sons, Ltd.
The hydrophobic effect in reaction mechanism studies and in catalysis by artificial enzymes
Authors: Breslow Ronald
Published: November 2006

Water is an environmentally benign solvent, easily cleaned and with a harmless vapor, so there is great interest in using water in chemical manufacturing. However, water also has important special properties as a solvent, with the hydrophobic effect promoting rapid and selective reactions in addition reactions, atom transfer reactions, and substitutions. The presence of the hydrophobic effect can be determined with the addition of prohydrophobic and antihydrophobic materials to the water solution. Using such materials, it is possible to determine the detailed geometry of transition states for a number of classical reactions, including alkylation of phenoxide ions on oxygen and carbon. The factors involved, particularly the effect of antihydrophobic agents such as ethanol in lowering the free energy of non‐polar reactants, have not been taken into account in previous well‐known mechanistic studies. Copyright © 2006 John Wiley & Sons, Ltd.
Relation between the substituent effect and aromaticity. Part II. The case of meta‐ and para‐homodisubstituted benzene derivatives
Authors: Krygowski Tadeusz M. , Dobrowolski Michal A. , Zborowski Krzysztof , Cyrański Michal K.
Published: November 2006

Thirty‐two mono‐ and homodisubstituted benzene derivatives (meta and para isomers) were optimized at B3LYP/6‐311+G** level of theory. The descriptors of cyclic π‐electron delocalization: aromatic stabilization energies (ASE), substituent effects stabilization energies (SESE), NICS and HOMA values were estimated for those systems. Generally, for monosubstituted systems the electron accepting substituents either stabilize the systems or weakly destabilize them. In contrast, the electron donating substituents destabilize the systems in all cases. The π‐electron stabilization/destabilization effects for para‐di‐homosubstituted benzene derivatives are much stronger than those for the meta analogs. Copyright © 2006 John Wiley & Sons, Ltd.
Kinetic solvent effects on the thermal decomposition reaction of acetone triperoxide
Authors: Eyler Gladys Nora
Published: November 2006

The kinetic data of the thermal decomposition reaction of acetone cyclic triperoxide (3,3,6,6,9,9‐hexamethyl‐1,2,4,5,7,8‐hexaoxacyclononane, ACTP) are reported for a wide range of organic solvents (acetone, toluene, 2‐propanol, 2‐methoxyethanol, n‐butylamine, diethylamine, triethylamine, and chlorobenzene) at 0.02 M initial concentration and in the temperature range of 135.0–172.0 °C. The thermolysis reaction follows pseudo first‐order kinetic laws up to at least ca. 70% ACTP conversion. The results indicate the importance of solvent polarity and specific solvent‐peroxide interactions in governing the rates of the reactions. The activation enthalpy and entropy of the thermal decomposition reaction of this triperoxide in several organic solvents were correlated through “isokinetic relationships” to verify the existence of a genuine solvent effect on this reaction. Other cyclic organic di‐ and triperoxides and some cyclic trioxanes showed a similar behavior, in contrast to the pinacolone cyclic diperoxide (PDP), probably due to a relatively great steric hindrance of this molecule. Copyright © 2006 John Wiley & Sons, Ltd.
Electronic structure of the 6+6 dimer of tropone
Authors: Reingold I. D. , Kowalski J. A. , Cummings G. C. , Gleiter R. , Lange H. , Lovell S. , Kahr B. , Aflatooni K. , Burrow P. D. , Gallup G. A.
Published: November 2006

Photoelectron and electron transmission (ET) spectroscopy were used to determine the ionization potentials and vertical electron attachment energies, respectively, of the 6 + 6 dimer of tropone. These measurements are combined with electronic structure calculations to provide insight into the extent of the coupling between the two cycloheptadienone ring systems. The ground state anion is predicted to be slightly stable as a consequence of the interaction between the π* orbitals of the CO and butadiene groups. Copyright © 2006 John Wiley & Sons, Ltd.
Study of the bromide ion reaction with methyl naphthalene‐2‐sulfonate in water–DMSO TTAB micellar solutions
Authors: Moyá María Luisa , Rodríguez Amalia , Muñoz María , Graciani María del Mar , Fernández Gaspar
Published: November 2006

The reaction of bromide ions with methyl naphthalene‐2‐sulfonate (MeNS) has been investigated in water–dimethyl sulfoxide, DMSO, tetradecyltrimethylammonium bromide, TTAB, micellar solutions, with the weight percentage of DMSO up to 50%. In order to quantitatively rationalize the micellar kinetic effects observed, conductivity, surface tension, and steady‐state fluorescence measurements were used to get information about the micellar reaction media. Results showed that changes caused by the addition of different amounts of DMSO to TTAB aqueous micellar solutions are made evident from the kinetic micellar effects, these being a helpful tool to obtain information on the micellar reaction media in the presence of the added organic solvent. Copyright © 2006 John Wiley & Sons, Ltd.
Effects of prayer and religious expression within computer support groups on women with breast cancer
Authors: Shaw Bret , Han Jeong Yeob , Kim Eunkyung , Gustafson David , Hawkins Robert , Cleary James , McTavish Fiona , Pingree Suzanne , Eliason Patricia , Lumpkins Crystal
Published: November 2006

Research indicates that two common ways breast cancer patients or women with breast cancer cope with their diagnosis and subsequent treatments are participating in computer support groups and turning to religion. This study is the first we are aware of to examine how prayer and religious expression within computer support groups can contribute to improved psychosocial outcomes for this population. Surveys were administered before group access and then 4 months later. Message transcripts were analyzed using a word counting program that noted the percentage of words related to religious expression. Finally, messages were qualitatively reviewed to better understand results generated from the word counting program. As hypothesized, writing a higher percentage of religion words was associated with lower levels of negative emotions and higher levels of health self‐efficacy and functional well‐being, after controlling for patients' levels of religious beliefs. Given the proposed mechanisms for how these benefits occurred and a review of the support group transcripts, it appeared that several different religious coping methods were used such as putting trust in God about the course of their illness, believing in an afterlife and therefore being less afraid of death, finding blessings in their lives and appraising their cancer experience in a more constructive religious light. Copyright © 2006 John Wiley & Sons, Ltd.
Spatial distribution of ground surface temperatures and active layer depths in the Hövsgöl area, northern Mongolia
Authors: Heggem E. S. F. , Etzelmüller B. , Anarmaa S. , Sharkhuu N. , Goulden C. E. , Nandinsetseg B.
Published: November 2006

Near‐surface temperature variations in different topographic settings were obtained from miniature temperature data‐loggers at 17 locations over a 2‐year period in the Lake Hövsgöl area in northern Mongolia. These measurements were used to analyse the influence of vegetation, solar radiation, surface wetness and snow cover on the ground thermal regime. An empirical modelling approach was applied in order to estimate the spatial distribution of ground surface temperatures, the presence of permafrost and the depth of the active layer. Our study shows that spatial interpolation of ground surface temperature parameters, mainly known from previous research in the Arctic, can be feasible in the arid mountain environments of Central Asia. Copyright © 2006 John Wiley & Sons, Ltd.
Esterase‐mediated bifenthrin resistance in a multiresistant strain of the two‐spotted spider mite, Tetranychus urticae
Authors: Van Leeuwen Thomas , Tirry Luc
Published: November 2006

A field‐collected multiresistant strain of Tetranychus urticae Koch exhibiting high resistance to bifenthrin was investigated in comparison with a susceptible laboratory strain. The esterase inhibitor S,S,S‐tributyl‐phosphorotrithioate (DEF) was able strongly to synergise bifenthrin toxicity in the resistant strain. Optimal conditions for determining esterase activities in T. urticae were determined, and a higher esterase activity towards several artificial substrates was found in this resistant strain, which had a preference for hydrolysing 4‐nitrophenyl butyrate. Bifenthrin was able to bind the active centres of T. urticae esterases in vitro, as was determined after competition experiments by a Dixon plot, revealing a higher affinity of bifenthrin in the resistant strain. Bifenthrin‐hydrolysing activity in the resistant and susceptible strains was examined in vitro and quantified with gas chromatography. A 7.2‐fold higher metabolising rate was found in the resistant strain. Copyright © 2006 Society of Chemical Industry
Selection of colour of sticky trap for monitoring adult bean thrips, Caliothrips fasciatus (Thysanoptera: Thripidae)
Authors: Harman J Alex , Mao Chang Xuan , Morse Joseph G
Published: November 2006

Adult bean thrips, Caliothrips fasciatus (Pergande), overwintering inside the navel of navel oranges shipped from California to Australia, are an actionable pest for the importing country, i.e. infested lots are fumigated with methyl bromide. Strict quarantine regulations regarding C. fasciatus prompted studies on the best colour sticky trap that might be used to monitor for bean thrips populations in the vicinity of California citrus groves prior to harvesting fruit for export. Preliminary experiments identified the most attractive trap of each of four colours (blue, green, white, yellow) commonly used to sample adult Thysanoptera. Three trials of a field study were conducted, comparing C. fasciatus capture on the best card of each colour using asparagus ferns naturally infested with high levels of this pest. Based on significantly higher catch on green sticky cards, this colour trap is recommended for potential use in California's bean thrips mitigation plan designed to reduce thrips levels on citrus exported to Australia. Copyright © 2006 Society of Chemical Industry
Synthesis, conformation, and bioactivity of novel analogues of the antiviral lipopeptide halovir A
Authors: Dalla Bona Andrea , Formaggio Fernando , Peggion Cristina , Kaptein Bernard , Broxterman Quirinus B. , Galdiero Stefania , Galdiero Massimiliano , Vitiello Mariateresa , Benedetti Ettore , Toniolo Claudio
Published: November 2006

We synthesized by solution‐phase methods three analogues, [L‐Leu6‐OMe], [L‐(αMe)Leu3, L‐Leu6‐OMe], and [L‐(αMe)Val4, L‐Leu6‐OMe] of halovir A. The [L‐Leu6‐OMe] analogue is known to be biologically equipotent to its naturally occurring, antiviral, lipopentapeptide amide parent compound. The preferred conformations of the L‐(αMe)Leu‐ and L‐(αMe)Val‐containing analogues, with a potentially reinforced helicity, were compared with those of [L‐Leu6‐OMe] halovir A and the natural peptide itself by use of a combination of FT‐IR absorption and NMR techniques. Measurements of the antiviral activities against herpes simplex virus type‐1 (HSV‐1) of halovir A and its three analogues were also carried out. Interestingly, the [L‐(αMe)Val4, L‐Leu6‐OMe] analogue exhibits the most significant activity in reducing HSV‐1 infectivity, notably higher than that of halovir A itself. Copyright © 2006 European Peptide Society and John Wiley & Sons, Ltd.
New bradykinin analogues substituted in positions 7 and 8 with sterically restricted 1‐aminocyclopentane‐1‐carboxylic acid
Authors: Labudda Olga , Wierzba Tomasz , Sobolewski Dariusz , Kowalczyk Wioleta , Śleszyńska MAłgorzata , Gawiński Łukasz , Plackova Marketa , Slaninová Jiřina , Prahl Adam
Published: November 2006

A sterically constrained non‐coded amino acid, 1‐aminocyclopentane‐1‐carboxylic acid (Apc), was introduced in position 7 or 8 of the bradykinin (BK) B2 receptor antagonist, [D‐Arg0, Hyp3, Thi5, 8, D‐Phe7]BK, previously synthesized by Stewart's group. This modification is believed to reduce the flexibility of the peptides, thereby forcing the peptide backbone and side chains to adopt specific orientations. Apc substitution was combined with acylation of the N‐terminus with 1‐adamantaneacetic acid (Aaa). The activity of four new analogues was assayed in isolated rat uterus and in rat blood pressure tests. The results clearly demonstrated that the Apc residue inserted in position 7 led to a reduction of antagonistic properties in the rat uterus assay or even restored the agonism in the blood pressure test, whereas Apc at position 8 enhanced antagonistic potency in both the tests. In both cases, acylation of the N‐terminus led to the enhancement of the antagonistic potency. On the basis of these findings, new potent and selective B2 blockers might be designed. Copyright © 2006 European Peptide Society and John Wiley & Sons, Ltd.
Synthesis, characterization and hybridization studies of new nucleo‐γ‐peptides based on diaminobutyric acid
Authors: Roviello G. N. , Moccia M. , Sapio R. , Valente M. , Bucci E. M. , Castiglione M. , Pedone C. , Perretta G. , Benedetti E. , Musumeci D.
Published: November 2006

In the present work, we report the synthesis and the characterization of a new chiral nucleoaminoacid, in which a diaminobutyric moiety is connected to the DNA nucleobase by an amidic bond, and its oligomerization to give the corresponding nucleo‐γ‐peptide. The ability of this synthetic polymer to bind complementary DNA was studied in order to explore its possible use in antigene/antisense or diagnostic applications. Our interest in the presented DNA analogue was also supported by the importance of γ‐aminoacid‐containing compounds in natural products of biological activity and by the known stability of γ‐peptides to enzymatic degradation. Furthermore, our work could contribute to the study of the role of nucleopeptides as prebiotic material in a PNA world that could successively lead to the actual DNA/RNA/protein world, as recently assumed. Copyright © 2006 European Peptide Society and John Wiley & Sons, Ltd.
High pressure Raman study of DyPO4 at room and low temperatures
Authors: Kontos A. G. , Stavrou E. , Malamos V. , Raptis Y. S. , Raptis C.
Published: November 2006

The Raman spectra of DyPO4, under variable hydrostatic pressure at room‐ and low‐temperature (110 K), have been studied. Crossing, with increasing pressure, of two modes in the frequency range of the internal‐external border, is observed and discussed. At low temperature, the pressure dependence of the three highest‐frequency internal modes is monitored, which exhibit a (dω /dP)‐slope differing, well beyond the experimental error, from the corresponding room temperature slopes. At room temperature, all the expected modes are observed and are divided in two distinct groups on a “logarithmic derivative” vs. “peak‐frequency” graph. This division is discussed in terms of the internal‐external mode‐character. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Evaluation of 384‐well formatted sample preparation technologies for regulated bioanalysis
Authors: Chang Min S. , Kim Elaine J. , El‐Shourbagy Tawakol A.
Published: November 2006

The capabilities and limitations of 384‐well formatted sample preparation technologies applied to regulated bioanalysis were evaluated by developing two assays for the simultaneous quantitation of lopinavir and ritonavir, the active ingredients of Kaletra. One method used liquid‐liquid extraction (LLE), and the other used solid‐phase extraction (SPE). The steps and apparatuses employed by the two methods covered most of those used for bioanalysis. Briefly, the previously validated 96‐well formatted assays were adapted to the 384‐format with minor modifications. Because the wells of a 384‐well plate are clustered together, cross‐contamination between adjacent wells was evaluated critically, along with sensitivity, assay throughput, and ruggedness. Samples (35 µL) containing plasma samples (15 µL), internal standard (10 µL), and sodium carbonate (0.5 M, 10 µL to basify the sample) were placed in a 384‐well microtiter plate that may contain saquinavir or amprenavir as contamination markers. For LLE preparation, the samples were placed in a deep 384‐well plate (300‐µL well volume) and extracted with 150 µL of ethyl acetate. Approximately 50 µL of the extracts were removed from each well after phase separation for analysis. For SPE preparation, the fortified samples were transferred to a 384‐formatted SPE plate (C18, 5 mg packing). The extracts were eluted from the plate with basified 2‐propanol. The LLE or SPE extracts were dried and reconstituted for column‐switching high‐performance liquid chromatography with tandem mass spectrometric detection (HPLC/MS/MS). The lower limit of quantitation and the assay range were the same as the 96‐well formatted assay. If combined with appropriate automation, sample preparation in the 384‐well format would be up to five times more efficient than the 96‐well format. Copyright © 2006 John Wiley & Sons, Ltd.
Direct MS/MS analysis in mammalian tissue sections using MALDI‐QIT‐TOFMS and chemical inkjet technology
Authors: Shimma Shuichi , Furuta Masaru , Ichimura Katsuhiko , Yoshida Yoshikazu , Setou Mitsutoshi
Published: November 2006

Mass spectrometry on 2D samples is known as imaging mass spectrometry, which enables us to visualize molecular distribution on a tissue surface. This technology has been developed using matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometers (MALDI‐TOFMS). However, it is difficult to determine constituents of interested regions on the tissue sections. We developed the methodology to overcome this problem. We designated it on‐tissue digestion. It is performed with the chemical inkjet technology to apply enzymes and the matrix‐assisted laser desorption/ionization‐quadrupole ion trap‐time‐of‐flight tandem mass spectrometer (MALDI‐QIT‐TOFMS) to identify molecules directly on the tissue surface. This technique provided us with a tool for an in‐depth understanding of composites of biostructures, especially proteins. Copyright © 2006 John Wiley & Sons, Ltd.
Size analysis of water cluster ions and their irradiation effects on solid surfaces
Authors: Takaoka Gikan H. , Nakayama Kazuya , Noguchi Hidetaka , Kawashita Masakazu
Published: November 2006

This article reports the development of a liquid cluster ion source. When water vapor was injected through a nozzle into a high‐vacuum region, water clusters were produced at vapor pressures greater than 1 atm. The size of the water cluster ions was measured by the time‐of‐flight (TOF) method, and it was distributed between a few hundreds and a few tens of thousands of molecules. The intensity of the water cluster ions increased with increase of the vapor pressure, and the peak size was about 2500 molecules per cluster. The effects of irradiation by water cluster ions on solid surfaces such as Si(100) and SiO2 surfaces were investigated. The sputtered depth of the Si and SiO2 surfaces increased with increase of the acceleration voltage, and the SiO2 surfaces were sputtered more than the Si surfaces. The sputtering yields at an acceleration voltage of 9 kV were 17.8 atoms per ion for Si and 17.1 molecules per ion for SiO2, which were approximately ten times larger than that for Ar monomer ion irradiation. Rutherford backscattering spectroscopy (RBS) measurement showed that the number of displacement atoms for irradiation by water cluster ions on the Si surfaces at ion doses larger than 1 × 1015 ions/cm2 was less than that for Ar monomer ion irradiation at the same acceleration voltage. In addition, the ellipsometry and X‐ray photoelectron spectroscopy (XPS) measurements showed that the thickness of the oxide layer formed on the Si surface increased with increase of the acceleration voltage, and it was between 10 nm and 15 nm at an acceleration voltage of 9 kV. Copyright © 2006 John Wiley & Sons, Ltd.
Ion beam analysis of dependence of the D–H replacement speed on trivalent impurity concentration in D‐implanted oxide ceramics exposed to H2O vapor at room temperature
Authors: Morita Kenji , Tsuchiya Bun , Nagata Shinji , Katahira Koji
Published: November 2006

The speed of D–H replacement in D‐implanted BaCe1−XYXO3−δ and SrCe1−XYbXO3−δ, exposed to H2O vapor at room temperature has been studied as a function of X by use of the ERD technique with 1.7 MeV He+ ion beam. The decay curve of D and growth curve of H in the specimens have been measured as a function of exposure time, and the decay constants of D, namely the D–H replacement speeds, have been obtained by fitting the experimental curves to the theoretical curves of D decay and H growth, which are derived from the mass balance equations described on the one‐way diffusion model for the D–H replacement: absorption of H+ due to splitting of H2O physisorbed at the surface, diffusion of H+ and emission of D implanted in the traps as HD molecule due to bulk recombination of H+ and subsequent trapping of H+ in the vacant trap.

It is found for both specimens that the decay constants of D, proportional to the absorption coefficient and the molecular formation coefficient of HD, increase, and after a maximum at X = 0.05–0.1 decrease as X increases, and the absolute experimental values for BaCe1−XYXO3−δ are larger almost by an order of magnitude than those of SrCe1−XYbXO3−δ. These experimental results are discussed in terms of the one‐way diffusion model on D–H replacement and water splitting model at the surface. Copyright © 2006 John Wiley & Sons, Ltd.
On the understanding and the optimization of ToF‐SIMS depth profiles by cosputtering cesium and xenon
Authors: Brison J. , Houssiau L.
Published: November 2006

In this work, the ToF‐SIMS depth profiles of a gold layer deposited on a bare silicon wafer were studied by cosputtering cesium and xenon. Firstly, a pure cesium depth profile was measured and the transient region at the interface between the gold layer and the silicon substrate was investigated. Secondly, several depth profiles of the Au layer were performed with varying cesium beam concentrations and the intensities of the positive signals (i.e. Au+, Si+, CsAu+, CsSi+, Cs2+, etc.) were monitored. The intensities of the signals were plotted with respect to the cesium surface concentration and were modeled according to the tunneling model. The study of these curves permitted us to understand and to optimize the ToF‐SIMS depth profile of the Au/Si system. Copyright © 2006 John Wiley & Sons, Ltd.
Electronic and mechanical properties of MoS2‐Ix nanotubes and Mo6SxIy nanowires
Authors: Hassanien A. , Leintschnig G. , Mrzel A. , Tokumoto M. , Kataura H.
Published: November 2006

We present scanning probe microscopy investigations of metal dichalcogenide nanotubes and wires (MDNW) in order to explore their structure and electronic properties. Local spectroscopy shows that the electronic properties are very sensitive to the stoichiometry of the nanowires, which can be controlled by adjusting the synthesis conditions. Unlike their carbon counterparts, MDNW can be fabricated to yield mainly single‐phase material, which makes their use as devices more feasible. In addition, we find also remarkable mechanical properties, where the molecules can be cut, recombined or deformed without any loss of structural integrity. We demonstrate this by mechanically deforming Mo6SxIy nanowires to highly strained configurations without causing irreversible changes to their structures. The rupturing and/or welding process of these nanowires, using AFM manipulation, shows that the molecules stretch to more than 30% of their relaxed configuration before plastic deformation occurs. Copyright © 2006 John Wiley & Sons, Ltd.
Formation of metal nano‐wires on heat‐treated substrates using an ultrahigh vacuum transmission electron microscope
Authors: Tanaka M. , Wagner T. , Takeguchi M. , Han M. , Shimojo M. , Mitsuishi K. , Furuya K.
Published: November 2006

Formation of metal nano‐islands on heat‐treated substrates by either conventional deposition or by electron beam–induced chemical vapour deposition (EBI‐CVD) was performed at elevated temperatures in an ultrahigh vacuum transmission electron microscope (UHV‐TEM). Pd islands on SrTiO3 (001) substrates, Pd silicide islands on Si (111) substrates, and Fe silicide islands on Si (111) substrates showed bimodal island growth; both substrates blocked islands and nano‐wires. The morphologies of these islands are suggested to be sensitive to the substrate conditions because of heat treatment before deposition. Selective growth of the nano‐wires was successful in the case of EBI‐CVD. Copyright © 2006 John Wiley & Sons, Ltd.
Surface structures of Ni2P (0001)—scanning tunneling microscopy (STM) and low‐energy electron diffraction (LEED) characterizations
Authors: Moula Md. Golam , Suzuki Shushi , Chun Wang‐Jae , Otani Shigeki , Oyama S. Ted , Asakura Kiyotaka
Published: November 2006

The Ni2P (0001) single crystal surface was characterized by low‐energy electron diffraction (LEED) and scanning tunneling microscopy (STM) to determine the atomic‐scale structure of the surface. LEED patterns revealed the presence of a sharp (1 × 1) structure and a reconstructed structure (2/3 × 2/3), while STM measurements showed only a well‐ordered (1 × 1) hexagonal structure. We found that the reconstructed (2/3 × 2/3) structure might be related to a Ni rearrangement that maintains the phosphorus (1 × 1) structure. Copyright © 2006 John Wiley & Sons, Ltd.
A comparison of the electron‐stimulated desorption of positive ions from NaCl‐type alkali chloride thin films
Authors: Markowski Leszek
Published: November 2006

Electron‐stimulated desorption of positive ions from thin layers of alkali chlorides deposited onto Si(111) are investigated by the time‐of‐flight (TOF) technique. All the experiments have been performed under the same experimental conditions, using very low electron current densities for which the obtained data are not distorted by the charging‐up effect, which in consequence allows a direct comparison of the relative ion yields, the kinetic‐energy distributions of emitted chlorine and alkali ions, and their isotope effects. The determined isotope effect of the chlorine (35Cl+/37Cl+) desorption yield appears to be independent of the alkali component mass and its values are 1.21 ± 0.02, 1.297 ± 0.005, 1.23 ± 0.02, and 1.24 ± 0.05 for LiCl, NaCl, KCl, and RbCl, respectively. On the other hand, the chlorine ion emission yields and average kinetic energies of the ions increase with increasing mass of the alkali component, which suggests that the lattice relaxation processes influence the desorption process. The most probable kinetic energies of 35Cl+ are 0.7, 1.4, 1.7, and 2.3 eV for LiCl, NaCl, KCl, and RbCl, respectively. The observed isotope effect for alkali ions decreases somewhat with increasing ion mass. The respective values are 1.282 ± 0.004, 1.04 ± 0.02, and 1.07 ± 0.02 for 6Li+/7Li+, 39K+/41K+, and 85Rb+/87Rb+. The alkali ion emission yield tends at first to increase with mass, reaching a maximum for potassium, but then for rubidium the yield drops to the value almost the same as for lithium. The desorption yields of alkali ions appear to be correlated with their most probable kinetic energies, which are 1.4, 1.1, 1.8, and 1.5 eV for 7Li+, 23Na+, 39K+, and 85Rb+, respectively. The obtained results and the role of the different parameters are discussed in view of possible mechanisms and processes involved in chlorine ion desorption. Copyright © 2006 John Wiley & Sons, Ltd.
Photoelectron angular distribution of 2H‐NbSe2 studied by a display‐type spherical mirror analyzer and circularly polarized light
Authors: Guo Fangzhun , Matsushita Tomohiro , Matui Fumihiko , Kato Yukako , Daimon Hiroshi
Published: November 2006

Photoelectron angular distributions (PEAD) of 2H‐NbSe2 were studied by using a display‐type spherical mirror analyzer (DIANA) and circularly polarized light. Forward focusing peaks in a wide acceptance angle of ± 60° are clearly observed. The forward focusing peaks in the two PEAD patterns taken with clockwise (cw) and counterclockwise (ccw) circularly polarized light show the three‐dimensional atomic arrangements around specific atoms. Three‐dimensional atomic arrangements up to at least the third nearest‐neighbor layer atoms upon the Nb layer were observed. The characteristic of this experimental method is the full application of the forward focusing peak rotation due to the exciting circularly polarized light. Copyright © 2006 John Wiley & Sons, Ltd.
Dependence of surface effects in photoelectron and Auger electron angular distribution on glancing incidence of X rays
Authors: Zhang Z. M. , Chen T. , Shimizu R. , Yoshikawa H. , Koshikawa T. , Ding Z. J.
Published: November 2006

On the basis of a dielectric function model, we considered the dependence of the surface excitation parameter (SEP) on incidence angle of X rays and derived a simple expression for the angular distribution of photoelectrons and Auger electrons including all surface effects. By applying the incidence‐angle‐dependent SEP, the discrepancy between experimental and theoretical results for the glancing incidence case was improved, and the modified theoretical result agrees with the experimental measurements. Copyright © 2006 John Wiley & Sons, Ltd.
Enhanced diffusion of boron in silicon by cw CO2 laser irradiation
Authors: Yamada‐Kaneta H. , Tanahashi K. , Kakimoto K. , Suto S.
Published: November 2006

We investigated the diffusion of boron (B) by the irradiation with cw CO2 laser light. The enhanced diffusion of B was observed by irradiating with the laser light during annealing in Ar/O2 ambient. We found that irradiation with laser light had the effect of enhancement on the growth of the oxide layer. The possible mechanism is that the excess self‐interstitials injected by oxidation at the laser‐irradiated point enhance the diffusion of B. Copyright © 2006 John Wiley & Sons, Ltd.
Dependence of depth resolution on primary energy of low‐energy Ar+ Ions (100–1000 eV) in AES sputter depth profiling of GaAs/AlAs superlattice
Authors: Bungo T. , Nagatomi T. , Takai Y.
Published: November 2006

The dependence of the depth resolution on the primary energy of low‐energy Ar+ ions in Auger electron spectroscopy (AES) sputter depth profiling of an ISO reference material GaAs/AlAs superlattice was investigated for the ion incidence angle of 50° from the sample surface normal. The depth resolution was found to improve as the square root of the primary energy of the ions as the primary energy decreased from 1000 to 200 eV. In contrast, a deterioration of the depth resolution was observed at 100 eV, which was induced by the difference in the etching rates between GaAs and AlAs and preferential sputtering. Further investigation of AES sputter depth profiling under irradiation of 100‐eV Ar+ ions at the incident angle of 70° revealed that the difference in the etching rate and preferential sputtering could be suppressed by changing the incident angle from 50° to 70° , leading to a depth resolution of ∼1.3 nm with 100 eV. The present results confirmed that glancing incidence is effective in achieving higher depth resolution from the point of view of the reduction of not only atomic mixing but also the difference in the etching rates and preferential sputtering. Careful attention is required for optimizing conditions of low‐energy ion irradiation in sputter depth profiling using the GaAs/AlAs reference material. Copyright © 2006 John Wiley & Sons, Ltd.
Real‐space visualization of the phase transition of the In/Si(111) system
Authors: Lee Geunseop
Published: November 2006

Low‐energy electron diffraction and scanning tunneling microscopy (STM) were used to investigate the temperature‐induced phase transition of a room‐temperature 4 × 1 (4 × 1‐RT) phase of the In/Si(111) surface to a low‐temperature 8 × 2 (8 × 2‐LT) phase. Upon cooling, dark, one‐dimensional (1D) stripes appear inhomogeneously within the 4 × 1‐RT phase at temperatures above a transition temperature (Tc), coalesce to form two‐dimensional (2D) islands, and the overall surface finally transforms into the 8 × 2‐LT phase below Tc. The local current–voltage spectroscopy reveals that the dark 1D stripes inherit the nature of the low‐temperature phase, distinguishing it from the defect‐induced period‐doubling modulations. The fluctuations of the 1D stripes are observed in successive STM images. The presence of defects suppresses the 1D fluctuations, while it is obstructive to the 2D condensation of the LT phase below Tc. Copyright © 2006 John Wiley & Sons, Ltd.