bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design of Hydrophobic Polyoxometalate Hybrid Assemblies Beyond Surfactant Encapsulation
Authors: Song Yu‐Fei , McMillan Nicola , Long De‐Liang , Thiel Johannes , Ding Yulong , Chen Haisheng , Gadegaard Nikolaj , Cronin Leroy 
Published: February 2008

AbstractGrafting of C‐6, C‐16 and C‐18 alkyl chains onto the hydrophilic Mn‐Anderson clusters (compounds 2–4) has been achieved. Exchange of the tetrabutyl ammonium (TBA) with dimethyldioctadecyl ammonium (DMDOA) results in the formation of new polyoxometalate (POM) assemblies (compounds 5–6), in which the POM cores are covalently functionalized by hydrophilic alkyl‐chains and enclosed by surfactant of DMDOABr. As a result, we have been able to design and synthesize POM‐containing hydrophobic materials beyond surfactant encapsulation. In solid state, scanning electron and transmission electron microscopy (SEM and TEM) studies of the TBA salts of compounds 3 and 4 show highly ordered, uniform, reproducible assemblies with unique segmented rodlike morphology. SEM and TEM studies of the DMDOA salts of compounds 5 and 6 show that they form spherical and sea urchin 3D objects in different solvent systems. In solution, the physical properties of compound 5 and 6 (combination of surfactant‐encapsulated cluster (SEC) and surface‐grafted cluster (SGC)) show a liquid‐to‐gel phase transition in pure chloroform below 0 °C, which are much lower than other reported SECs. By utilizing light scattering measurements, the nanoparticle size for compounds 5 and 6 were measured at 5 °C and 30 °C, respectively. Other physical properties including differential scanning calorimetry have been reported.
Design and construction of a microcoil NMR probe for the routine analysis of 20‐μL samples
Authors: Henry Ian D. , Park Gregory H.J. , Kc Ravi , Tobias Brian , Raftery Daniel 
Published: February 2008

AbstractRecent advances in microcoil NMR have provided commercially available, robust methodologies for analyzing mass and volume limited samples in the low microliter regime, and the technology has been applied in a number of areas. Unfortunately, due to constraints on sample size and the limited solubility of some compounds of interest, the application of this approach to certain areas of development, such as the structural analysis of chromatography eluates, is restricted. A current challenge is to provide an option within a previously unexplored sample size regime (tens of microliters) while still taking advantage of the increase in mass sensitivity afforded by solenoidal microcoil NMR. In this article, we present the design and construction of a microcoil NMR probe with a custom detection cell for the routine analysis of 20‐μL samples. The detection cell is comprised of a CO2‐laser‐heated HF‐etched borosilicate active volume with fused silica transfer lines added to provide sample input and output. This setup produces an enlarged sample bubble within the detection coil and provides easy connection with 1/16 in. standard LC connections, lending itself to applications with HPLC‐NMR, online SPE and similar separation techniques, as well as higher‐throughput robotic automation. NMR performance characteristics determined using standard compounds showed the probe exhibited reasonable resolution (<0.01 ppm), although sensitivity was less than optimal due to tuning constraints. Future improvements and opportunities are also discussed. © 2008 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 33B: 1–8, 2008
Minimizing the induced fields in MRI occupational workers by lowering the imager
Authors: Trakic A. , Wang H. , Liu F. , Lopez H.S. , Weber E. , Crozier S. 
Published: February 2008

AbstractIn magnetic resonance imaging (MRI), healthcare workers can be exposed to strong static and time‐varying magnetic fields outside the imager. Body motion through the large, spatially nonuniform static magnetic field generated by the main magnet and exposure to low‐frequency magnetic fields from pulsed gradient coils can lead to the stimulation of electric fields in the body. Tissue of the central and peripheral nervous system (CPNS) in the head and torso is particularly susceptible. To protect occupational workers, the member states of the European Union are required to incorporate the physical agents directive (PAD) 2004/40/EC into their legislation, which could restrict the use of MRI in some cases. This article reports a rather simple and general method/solution that can notably reduce the head/trunk exposure of MRI operators to both static and (low‐frequency) time‐dependant magnetic fields in MRI. It is numerically shown that the upper body CPNS exposure can be reduced by factors of up to 50 or more, when the MRI machine is simply lowered by 1 m in height relative to the ground floor. The proposed approach can lead to significantly reduced in situ electric fields/current in the upper body and thus allow faster worker motions around the lowered imager. © 2008 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 33B: 39–54, 2008
Wilms tumor gene protein 1 is associated with ovarian cancer metastasis and modulates cell invasion
Authors: Barbolina Maria V. , Adley Brian P. , Shea Lonnie D. , Stack M. Sharon 
Published: February 2008

AbstractBACKGROUNDAlthough metastatic disease is the primary cause of death from epithelial ovarian carcinoma, to the authors' knowledge the cellular mechanisms that regulate intraperitoneal metastasis are largely unknown. Metastasizing ovarian carcinoma cells encounter a collagen‐rich microenvironment because the submesothelial matrix is comprised mainly of interstitial collagens Types I and III.METHODSImmunohistochemistry using primary and metastatic ovarian carcinoma samples was employed to detect expression of Wilms tumor gene protein 1 (WT1). Three‐dimensional (3D) collagen culture, real‐time reverse transcriptase‐polymerase chain reaction, and immunofluorescent staining were used to evaluate changes in WT1 RNA and protein expression in response to 3D collagen culture. Boyden chamber invasion assay, scratch‐wound motility assay, and Western blot analysis were used to establish the function of WT1 in ovarian carcinoma cells.RESULTSTo model intraperitoneal invasion in vitro, ovarian cancer cells were cultured in a 3D collagen microenvironment. 3D collagen culture resulted in robust induction of WT1 at the mRNA and protein levels. WT1 expression was prevalent in primary ovarian tumors and was retained in paired peritoneal metastases. Functional studies supported a role for WT1 in intraperitoneal invasion, because siRNA knockdown of WT1 expression reduced the ability of ovarian cancer cells to invade 3D collagen gels.CONCLUSIONSThe data from the current study identify a novel regulatory mechanism for the control of WT1 expression and provide evidence for a functional role of WT1 protein in the control of cellular invasive activity. Cancer 2008. ©2008 American Cancer Society.
Tuning of cell proliferation on tough gels by critical charge effect
Authors: Chen Yong Mei , Gong Jian Ping , Tanaka Masaru , Yasuda Kazunori , Yamamoto Sadaaki , Shimomura Masatsugu , Osada Yoshihito 
Published: February 2008

AbstractTough triple network (TN) hydrogels that facilitate cell spreading and proliferation and, at the same time, preserve high mechanical strength are synthesized by the introduction of a proper component of negatively charged moiety, poly(2‐acrylamido‐2‐methyl‐propane sulfonic acid sodium salt) (PNaAMPS), on which cells proliferate, with neutral moiety, poly(N,N‐dimethylacrylamide) (DMAAm), on which cells do not proliferate, as the third network component, to PNaAMPS/PDMAAm double network (DN) gels. For synthesizing the tough TN gels to support cell viability, the effect of charge density on the behaviors of three kinds of cells, bovine fetal aorta endothelial cells (BFAECs), human umbilical endothelial cells (HUVECs), and rabbit synovial tissue‐derived fibroblast cells (RSTFCs) were systematically investigated on poly(NaAMPS‐co‐DMAAm) gels with different charge density. The charge density of the gels was tuned by changing the molar fraction (F) of negatively charged monomer in the copolymer hydrogels. Critical F, which corresponds to a critical value of the zeta potential (ζ), is observed for cell spreading and proliferation. The critical F for BFAECs and HUVECs proliferate to confluent is F = 0.4 (ζ = −20 mV), whereas the critical F for RSTFCs shifts to F = 0.7 (ζ = −28.5 mV). The effect of gel charge density on cell behavior is correlated well with the total adsorbed proteins and fibronectin. By applying these results, cell proliferation is successfully realized on the tough TN hydrogels without surface modification with any cell adhesive proteins or peptides. The results will substantially promote the application of tough hydrogels as soft and wet tissues. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Protective effects of R‐alpha‐lipoic acid and acetyl‐L‐carnitine in MIN6 and isolated rat islet cells chronically exposed to oleic acid
Authors: Shen Weili , Liu Kai , Tian Chuan , Yang Lu , Li Xuesen , Ren Jinmin , Packer Lester , Head Elizabeth , Sharman Edward , Liu Jiankang 
Published: February 2008

AbstractMitochondrial dysfunction due to oxidative stress and concomitant impaired β‐cell function may play a key role in type 2 diabetes. Preventing and/or ameliorating oxidative mitochondrial dysfunction with mitochondria‐specific nutrients may have preventive or therapeutic potential. In the present study, the oxidative mechanism of mitochondrial dysfunction in pancreatic β‐cells exposed to sublethal levels of oleic acid (OA) and the protective effects of mitochondrial nutrients [R‐alpha‐lipoic acid (LA) and acetyl‐L‐carnitine (ALC)] were investigated. Chronic exposure (72 h) of insulinoma MIN6 cells to OA (0.2–0.8 mM) increased intracellular oxidant formation, decreased mitochondrial membrane potential (MMP), enhanced uncoupling protein‐2 (UCP‐2) mRNA and protein expression, and consequently, decreased glucose‐induced ATP production and suppressed glucose‐stimulated insulin secretion. Pretreatment with LA and/or ALC reduced oxidant formation, increased MMP, regulated UCP‐2 mRNA and protein expression, increased glucose‐induced ATP production, and restored glucose‐stimulated insulin secretion. The key findings on ATP production and insulin secretion were verified with isolated rat islets. These results suggest that mitochondrial dysfunction is involved in OA‐induced pancreatic β‐cell dysfunction and that pretreatment with mitochondrial protective nutrients could be an effective strategy to prevent β‐cell dysfunction. J. Cell. Biochem. 104: 1232–1243, 2008. © 2008 Wiley‐Liss, Inc.
Attention mediates radiation's impact on daily living skills in children treated for brain tumors
Authors: Papazoglou Aimilia , King Tricia Z. , Morris Robin D. , Morris Mary K. , Krawiecki Nicolas S. 
Published: February 2008

AbstractBackgroundRadiotherapy is associated with an increased survival rate in children with brain tumors, but also with cognitive decline. This study examined the time‐dependent effects of radiation treatment on adaptive functioning in children with brain tumors. The potentially mediating effects of attention span (Trial 1 of the Rey Auditory Verbal Learning Test [RAVLT]) assessed within 7 years of diagnosis were explored.ProcedureTwenty‐two children treated with cranial radiation for third ventricle or cerebellar tumors were included in this archival study. The mean age at diagnosis was 7.62 years (SD = 4.78) and 10.16 years (SD = 3.83) at evaluation. We examined the extent to which auditory attention span was able to mediate the relationship between time elapsed since the initiation of radiation treatment (M = 2.43 years; SD = 2.37) and adaptive functioning (Vineland Adaptive Behavior Scales [VABS]).ResultsAttention span was found to mediate the relationship between time since the initiation of radiation and daily living skills. These findings were shown to be specific to attention and not a reflection of generalized neuropsychological decline, nor were they a result of increasing time since diagnosis in and of itself.ConclusionsThe results of this study suggest that time since radiation may directly decrease attention and poor attention in turn may be associated with lower adaptive functioning on tasks of daily living. Pediatr Blood Cancer 2008;50:1253–1257. © 2008 Wiley‐Liss, Inc.
Unfolding energetics and stability of banana lectin
Authors: Gupta Garima , Sinha Sharmistha , Surolia Avadhesha 
Published: February 2008

AbstractThe unfolding pathway of banana lectin from Musa paradisiaca was determined by isothermal denaturation induced by the chaotrope GdnCl. The unfolding was found to be a reversible process. The data obtained by isothermal denaturation provided information on conformational stability of banana lectin. The high values of ΔG of unfolding at various temperatures indicated the strength of intersubunit interactions. It was found that banana lectin is a very stable and denatures at high chaotrope concentrations only. The basis of the stability may be attributed to strong hydrogen bonds of the order 2.5–3.1 Å at the dimeric interface along with the presence of water bridges. This is perhaps very unique example in proteins where subunit association is not a consequence of the predominance of hydrophobic interactions. Proteins 2008. © 2008 Wiley‐Liss, Inc.
New crystal structures of ColE1 Rom and variants resulting from mutation of a surface exposed residue: Implications for RNA‐recognition
Authors: Struble E. B. , Ladner J. E. , Brabazon D. M. , Marino J. P. 
Published: February 2008

AbstractIn ColE1, the plasmid encoded RNA one modulator (Rom) protein, which is also referred to as Rop, specifically binds and stabilizes an intermediate RNA loop–loop kissing structure formed between the plasmid encoded transcripts RNA I and RNA II and thereby acts as an auxiliary repressor of replication. Rom folds into a homodimeric, cylindrically packed four helix bundle with an exact twofold symmetry axis (Banner et al., J Mol Biol 1987;196:657–675; Eberle et al., J Biomol 1991;1:71–83). Previous studies (Castagnoli et al., EMBO J 1989;8:621–629; Predki et al., Cell 1995;80:41–50) have localized the RNA binding surface to the H1/H1′ face of the helical bundle and found Phe14 to be a key determinant of the binding affinity and specificity for RNA kissing complexes. To investigate the role of Phe14 in RNA recognition, we have determined high‐resolution crystal structures of two point mutants of Rom (F14Y and F14W), as well as a high‐resolution structure of a crystal form of Rom in which the dimer comprises the asymmetric unit. Although the structures of F14Y and F14W share a very high degree of structural identity with that of the wild‐type protein and each other, differences are observed between the three polypeptide chains found in the asymmetric unit of each crystal in the packing of the tryptophan and tyrosine side chains at position 14, as well as some of the other surface exposed side chains of key amino acids involved in RNA binding. In both the wild‐type Rom and mutant structures, crystal packing forces can break the exact twofold symmetry of the dimer and influence the conformation of the side chains presented on the H1/H1′ face of Rom. Since the new structures show such a high degree of structural identity, the disruption in RNA binding observed for the mutant proteins can be attributed specifically to the chemical nature of the side chain at position 14. Moreover, the fact that even subtle changes in the side chain at position 14 cannot be compensated for by the apparent flexibility of this side chain suggests a highly constrained packing of this residue in the RNA–protein complex. Proteins 2008. Published 2008 Wiley‐Liss, Inc.
Genome wide analysis of pathogenic SH2 domain mutations
Authors: Lappalainen Ilkka , Thusberg Janita , Shen Bairong , Vihinen Mauno 
Published: February 2008

AbstractThe authors have made a genome‐wide analysis of mutations in Src homology 2 (SH2) domains associated with human disease. Disease‐causing mutations have been detected in the SH2 domains of cytoplasmic signaling proteins Bruton tyrosine kinase (BTK), SH2D1A, Ras GTPase activating protein (RasGAP), ZAP‐70, SHP‐2, STAT1, STAT5B, and the p85α subunit of the PIP3. Mutations in the BTK, SH2D1A, ZAP70, STAT1, and STAT5B genes have been shown to cause diverse immunodeficiencies, whereas the mutations in RASA1 and PIK3R1 genes lead to basal carcinoma and diabetes, respectively. PTPN11 mutations cause Noonan sydrome and different types of cancer, depending mainly on whether the mutation is inherited or sporadic. We collected and analyzed all known pathogenic mutations affecting human SH2 domains by bioinformatics methods. Among the investigated protein properties are sequence conservation and covariance, structural stability, side chain rotamers, packing effects, surface electrostatics, hydrogen bond formation, accessible surface area, salt bridges, and residue contacts. The majority of the mutations affect positions essential for phosphotyrosine ligand binding and specificity. The structural basis of the SH2 domain diseases was elucidated based on the bioinformatic analysis. Proteins 2008. © 2008 Wiley‐Liss, Inc.
Peptide and protein loading into porous silicon wafers
Authors: Prestidge C. A. , Barnes T. J. , Mierczynska‐Vasilev A. , Kempson I. , Peddie F. , Barnett C. 
Published: February 2008

AbstractThe influence of peptide/protein size and hydrophobicity on the physical and chemical aspects of loading within porous silicon (pSi) wafer samples has been determined using Atomic Force Microscopy (AFM) and Time‐of‐Flight Secondary Ion Mass Spectroscopy (ToF‐SIMS). Both Gramicidin A (a small hydrophobic peptide) and Papain (a larger hydrophilic protein) were observed (ToF‐SIMS) to penetrate across the entire pSi layer, even at low loading levels. AFM surface imaging of pSi wafers during peptide/protein loading showed that surface roughness increased with Papain loading, but decreased with Gramicidin A loading. For Papain, the loading methodology was also found to influence loading efficiency. These differences indicate more pronounced surface adsorption of Papain. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Can silicon change photonics?
Authors: Jalali Bahram 
Published: February 2008

AbstractThe electronic chip industry embodies the height of technological sophistication and economics of scale. The industry mass produces complex circuitry, boasting over one billion components at such low cost that they appear in consumer products. Fabricating inexpensive photonic components by leveraging this mighty manufacturing infrastructure has been the impetus behind the development of silicon photonics. If it can be done economically and in an energy‐efficient manner, empowering silicon with optical functionality will bring optical communications to the realm of computers where limitations of metallic interconnects are threatening the industry's future. Guided by such visions and propelled by pioneering research conducted in the 1980s and 1990s, silicon photonics has enjoyed spectacular progress in the last six years. The critical size of photonic devices has been scaled to the 300 nm regime making more efficient use of wafer real estate. Optical amplification and lasing, once considered forbidden in silicon, have recently been demonstrated. High‐speed and efficient electrical‐optical conversion is being performed by production‐worthy devices. Silicon's nonlinear optical properties, enhanced by tight optical confinement in Si/SiO2structures, are producing wavelength switching and generation, which are central functions in multiwavelength communications and signal processing. This article reviews these and other exciting progress being made in silicon photonics and identifies the challenges that remain on the path to commercialization. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Indium oxide thin film transistors via reactive sputtering using metal targets
Authors: Qijun Yao , Dejie Li 
Published: February 2008

AbstractThin film transistors with In2O3 channel were fabricated. The channel layer of In2O3 and gate dielectric of Ta2O5 in the device was deposited by reactive sputtering using metal targets. A thin layer of Bi was deposited on the channel and then an‐ nealed to help stabilize the device performance. The device with optimal dose of Bi exhibited a channel mobility of 12 cm2/V s. Effects of Bi layer and influence of gate dielectric to the device performance are investigated. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A mass filter based on an accelerating traveling wave
Authors: Wiedenbeck Michael , Kasemset Bodin , Kasper Manfred 
Published: February 2008

AbstractWe describe a novel mass filtering concept based on the acceleration of a pulsed ion beam through a stack of electrostatic plates. A precisely controlled traveling wave generated within such an ion guide will induce a mass‐selective ion acceleration, with mass separation ultimately accomplished via a simple energy‐filtering system. Crucial for successful filtering is that the velocity with which the traveling wave passes through the ion guide must be dynamically controlled in order to accommodate the acceleration of the target ion species. Mass selection is determined by the velocity and acceleration with which the wave traverses the ion guide, whereby the target species will acquire a higher kinetic energy than all other lighter as well as heaver species. Finite element simulations of this design demonstrate that for small masses a mass resolution M/ΔM ≈ 1000 can be achieved within an electrode stack containing as few as 20 plates. Some of the possible advantages and drawbacks which distinguish this concept from established mass spectrometric technologies are discussed. Copyright © 2008 John Wiley & Sons, Ltd.
Detection of monobromamine, monochloramine and dichloramine using selected ion flow tube mass spectrometry and their relevance as breath markers
Authors: Senthilmohan Senti T. , Kettle Anthony J , McEwan Murray J. , Dummer Jack , Edwards Samuel J. , Wilson Paul F. , Epton Michael J. 
Published: February 2008

AbstractWe report a fast, sensitive, real‐time method to measure monobromamine, monochloramine and dichloramine using selected ion flow tube mass spectrometry (SIFT‐MS). Relative rate coefficients and product distributions are reported for the reagent ions H3O+ and O. Rapid reactions with the haloamines were observed with H3O+ and O but no fast reaction was found with NO+. A slow reaction between NO+ and dichloramine was observed. We demonstrate the feasibility of determining these compounds in a single human breath for which the limit of detection is approaching 10 parts per billion (ppb). We also report preliminary measurements of these compounds in the breath of individuals where the concentrations of bromamine and chloramine ranged from 10 to 150 ppb. Copyright © 2008 John Wiley & Sons, Ltd.