bluuebunny/crossref_metadata_2025 huggingface dataset:
Genome‐scale metabolic model integrated with RNAseq data to identify metabolic states of Clostridium thermocellum
Authors: Gowen Christopher M. , Fong Stephen S.
Published: July 2010

Constraint‐based genome‐scale metabolic models are becoming an established tool for using genomic and biochemical information to predict cellular phenotypes. While these models provide quantitative predictions for individual reactions and are readily scalable for any biological system, they have inherent limitations. Using current methods, it is difficult to computationally elucidate a specific network state that directly depicts an in vivo state, especially in the instances where the organism might be functionally in a suboptimal state. In this study, we generated RNA sequencing data to characterize the transcriptional state of the cellulolytic anaerobe, Clostridium thermocellum, and algorithmically integrated these data with a genome‐scale metabolic model. The phenotypes of each calculated metabolic flux state were compared to 13 experimentally determined physiological parameters to identify the flux mapping that best matched the in vitro growth of C. thermocellum. By this approach we found predicted fluxes for 88 reactions to be changed between the best solely computational prediction (flux balance analysis) and the best experimentally derived prediction. The alteration of these 88 reaction fluxes led to a detailed network‐wide flux mapping that was able to capture the suboptimal cellular state of C. thermocellum.
Metabolic systems analysis to advance algal biotechnology
Authors: Schmidt Brian J. , Lin‐Schmidt Xiefan , Chamberlin Austin , Salehi‐Ashtiani Kourosh , Papin Jason A.
Published: July 2010

Algal fuel sources promise unsurpassed yields in a carbon neutral manner that minimizes resource competition between agriculture and fuel crops. Many challenges must be addressed before algal biofuels can be accepted as a component of the fossil fuel replacement strategy. One significant challenge is that the cost of algal fuel production must become competitive with existing fuel alternatives. Algal biofuel production presents the opportunity to fine‐tune microbial metabolic machinery for an optimal blend of biomass constituents and desired fuel molecules. Genome‐scale model‐driven algal metabolic design promises to facilitate both goals by directing the utilization of metabolites in the complex, interconnected metabolic networks to optimize production of the compounds of interest. Network analysis can direct microbial development efforts towards successful strategies and enable quantitative fine‐tuning of the network for optimal product yields while maintaining the robustness of the production microbe. Metabolic modeling yields insights into microbial function, guides experiments by generating testable hypotheses, and enables the refinement of knowledge on the specific organism. While the application of such analytical approaches to algal systems is limited to date, metabolic network analysis can improve understanding of algal metabolic systems and play an important role in expediting the adoption of new biofuel technologies.
Genome‐scale metabolic modeling of a clostridial co‐culture for consolidated bioprocessing
Authors: Salimi Fahimeh , Zhuang Kai , Mahadevan Radhakrishnan
Published: July 2010

An alternative consolidated bioprocessing approach is the use of a co‐culture containing cellulolytic and solventogenic clostridia. It has been demonstrated that the rate of cellulose utilization in the co‐culture of Clostridium acetobutylicum and Clostridium cellulolyticum is improved compared to the mono‐culture of C. cellulolyticum, suggesting the presence of syntrophy between these two species. However, the metabolic interactions in the co‐culture are not well understood. To understand the metabolic interactions in the co‐culture, we developed a genome‐scale metabolic model of C. cellulolyticum comprising of 431 genes, 621 reactions, and 603 metabolites. The C. cellulolyticum model can successfully predict the chemostat growth and byproduct secretion with cellulose as the substrate. However, a growth arrest phenomenon, which occurs in batch cultures of C. cellulolyticum at cellulose concentrations higher than 6.7 g/L, cannot be predicted by dynamic flux balance analysis due to the lack of understanding of the underlying mechanism. These genome‐scale metabolic models of the pure cultures have also been integrated using a community modeling framework to develop a dynamic model of metabolic interactions in the co‐culture. Co‐culture simulations suggest that cellobiose inhibition cannot be the main factor that is responsible for improved cellulose utilization relative to mono‐culture of C. cellulolyticum.
Nociceptin and its natural and specifically‐modified fragments: Structural studies
Authors: Podstawka‐Proniewicz E. , Kosior M. , Kim Y. , Rolka K. , Proniewicz L. M.
Published: July 2010

The vibrational structures of Nociceptin (FQ), its short bioactive fragments, and specifically‐modified [Tyr1]FQ (1‐6), [His1]FQ (1‐6), and [His1,4]FQ (1‐6) fragments were characterized. We showed that in the solid state, all of the aforementioned peptides except FQ adopt mainly turn and disordered secondary structures with a small contribution from an antiparallel β‐sheet conformation. FQ (1‐11), FQ (7‐17) [His1]FQ (1‐6), and [His1,4]FQ (1‐6) have an α‐helical backbone arrangement that could also slightly influence their secondary structure. The adsorption behavior of these peptides on a colloidal silver surface in an aqueous solution (pH = ∼8.3) was investigated by means of surface‐enhanced Raman scattering (SERS). All of the peptides, excluding FQ (7‐17), chemisorbed on the colloidal silver surfaces through a Phe4residue, which for FQ, FQ (1‐11), FQ (1‐6), [Tyr1]FQ (1‐6), and [His1]FQ (1‐6) lies almost flat on this surface, while for FQ (1‐13) and FQ (1‐13)NH2adopts a slightly tilted orientation with respect to the surface. The Tyr1residue in [Tyr1]FQ (1‐6) does not interact with the colloidal silver surface, suggesting that the Tyr1and Phe4side chains are located on the opposite sides of the peptide backbone, which can be also true for His1and Phe4in [His1]FQ (1‐6). The lone pair of electrons on the oxygen atom of the ionized carbonyl group of FQ (1‐13) and FQ (7‐17) appears to be coordinated to the colloidal silver nanoparticles, whereas in the case of the remaining peptides, it only assists in the adsorption process, similar to the NH2group. We also showed that upon adsorption, the secondary structure of these peptides is altered. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 1039–1054, 2010.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Structural investigations on the Nodal‐Cripto binding: A theoretical and experimental approach
Authors: Calvanese Luisa , Marasco Daniela , Doti Nunzianna , Saporito Angela , D'Auria Gabriella , Paolillo Livio , Ruvo Menotti , Falcigno Lucia
Published: July 2010

Nodal, a member of the transforming growth factor‐β superfamily, is a potent embryonic morphogen also implicated in tumor progression. Up to date structural information on the interaction of Nodal with its molecular partners are unknown. To deepen our understanding about mechanisms underlying both embryonic development and Nodal/Cripto‐dependent tumor progression, we present here a molecular model of activin receptor‐like kinase 4/Cripto/Nodal complex built by homology modeling as well as docking tests aimed at identifying potential binding epitopes. Starting from this model, we have predicted a large interaction surface on Nodal, which encompasses residues 43–69 and includes the prehelix loop and the H3 helix. This hypothesis has been subsequently assessed by surface plasmon resonance binding assays between the full‐length Cripto and synthetic peptides reproducing the selected Nodal regions. In addition, the binding affinity between the full‐length Nodal and Cripto proteins has been evaluated for the first time. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 1011–1021, 2010.
Effect of the ΔPhe residue configuration on a didehydropeptides conformation: A combined CD and NMR study
Authors: Lisowski Marek , Jaremko Łukasz , Jaremko Mariusz , Mazur Adam , Latajka Rafał , Makowski Maciej
Published: July 2010

Conformations of two pairs of dehydropeptides with the opposite configuration of the ΔPhe residue, Boc‐Gly‐ΔZPhe‐Gly‐Phe‐OMe (Z‐OMe), Boc‐Gly‐ΔEPhe‐Gly‐Phe‐OMe (E‐OMe), Boc‐Gly‐ΔZPhe‐Gly‐Phe‐p‐NA (Z‐p‐NA), and Boc‐Gly‐ΔEPhe‐Gly‐Phe‐p‐NA (E‐p‐NA) were compared on the basis of CD and NMR studies in MeOH, trifluoroethanol (TFE), MeCN, chloroform, and dimethylsulfoxide (DMSO). The CD results were used as the additional input data for the NMR‐based determination of the detailed solution conformations of the peptides. It was found that E‐OMe is unordered and Z‐OMe, Z‐p‐NA, and E‐p‐NA adopt the β‐turn conformation. There are two overlapping β‐turns in each of those peptides: type II and type III′ in Z‐OMe and Z‐p‐NA, and two type III in E‐p‐NA. The ordered structure‐inducing properties of ΔZPhe and ΔEPhe in the peptides studied depend on the C‐terminal blocking group. In methyl esters, the ΔZPhe residue is a strong inducer of ordered conformations whereas the ΔEPhe one has no such properties. In p‐nitroanilides, both isomers of ΔPhe cause the peptides to adopt ordered structures to a similar extent. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 1055–1064, 2010.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Nitrifying bacterial growth inhibition in the presence of algae and cyanobacteria
Authors: Choi Okkyoung , Das Atreyee , Yu Chang‐Ping , Hu Zhiqiang
Published: July 2010

Nitrifying bacteria, cyanobacteria, and algae are important microorganisms in open pond wastewater treatment systems. Nitrification involving the sequential oxidation of ammonia to nitrite and nitrate, mainly due to autotrophic nitrifying bacteria, is essential to biological nitrogen removal in wastewater and global nitrogen cycling. A continuous flow autotrophic bioreactor was initially designed for nitrifying bacterial growth only. In the presence of cyanobacteria and algae, we monitored both the microbial activity by measuring specific oxygen production rate (SOPR) for microalgae and cyanobacteria and specific oxygen uptake rate (SOUR) for nitrifying bacteria. The growth of cyanobacteria and algae inhibited the maximum nitrification rate by a factor of 4 although the ammonium nitrogen fed to the reactor was almost completely removed. Terminal restriction fragment length polymorphism (T‐RFLP) analysis indicated that the community structures of nitrifying bacteria remained unchanged, containing the dominant Nitrosospira, Nitrospira, and Nitrobacter species. PCR amplification coupled with cloning and sequencing analysis resulted in identifying Chlorella emersonii and an uncultured cyanobacterium as the dominant species in the autotrophic bioreactor. Notwithstanding their fast growth rate and their toxicity to nitrifiers, microalgae and cyanobacteria were more easily lost in effluent than nitrifying bacteria because of their poor settling characteristics. The microorganisms were able to grow together in the bioreactor with constant individual biomass fractions because of the uncoupled solids retention times for algae/cyanobacteria and nitrifiers. The results indicate that compared to conventional wastewater treatment systems, longer solids retention times (e.g., by a factor of 4) should be considered in phototrophic bioreactors for complete nitrification and nitrogen removal. Biotechnol. Bioeng. 2010;107: 1004–1011. © 2010 Wiley Periodicals, Inc.
Synthesis and utilization of E. coli‐encapsulated PEG‐based microdroplet using a microfluidic chip for biological application
Authors: Lee Kyoung G. , Park Tae Jung , Soo Song Young , Wang Kye Won , Kim Byeong I.I. , Park Jae Hong , Lee Chang‐Soo , Kim Do Hyun , Lee Seok Jae
Published: July 2010

We report herein an effective strategy for encapsulating Escherichia coli in polyethylene glycol diacrylate (PEGDA) microdroplets using a microfluidic device and chemical polymerization. PEGDA was employed as a reactant due to the biocompatibility, high porosity, and hydrophilic property. The uniform size and shape of microdroplets are obtained in a single‐step process using microfluidic device. The size of microdroplets can be controlled through the changing continuous flow rate. The combination of microdroplet generation and chemical polymerization techniques provide unique environment to produce non‐toxic ways of fabricating microorganism‐encapsulated hydrogel microbeads. Due to these unique properties of micro‐sized hydrogel microbeads, the encapsulated E. coli can maintain viability inside of microbeads and green fluorescent protein (GFP) and red fluorescent protein (RFP) genes are efficiently expressed inside of microbeads after isopropyl‐β‐D‐thiogalactopyranoside induction, suggesting that there is no low‐molecular weight substrate transfer limitation inside of microbeads. Furthermore, non‐toxic, gentle, and outstanding biocompatibility of microbeads, the encapsulated E. coli can be used in various applications including biotransformation, biosensing, bioremediation, and engineering of artificial cells. Biotechnol. Bioeng. 2010;107:747–751. © 2010 Wiley Periodicals, Inc.
Efficiency Optimization and Prediction in High‐Gradient Magnetic Centrifugation
Authors: Lindner J. , Wagner K. , Eichholz C. , Nirschl H.
Published: July 2010

In order to separate small magnetizable particles down to the micro‐ and nanometer scale, high‐gradient magnetic separation is a well‐established process. The superposition of magnetic filtration with centrifugation, called magnetic field‐enhanced centrifugation, permits continuous separation. The separation efficiency of magnetic filters and the prediction of the efficiency is described. The separation efficiency of one single stage could be enhanced from 51 to 78 % by increasing the wire number and improving the wire cross section. The separation efficiency on different particle sizes at different filter stage numbers and comparison to the prediction of separation efficiency based on magnetic forces and the fluid drag force is demonstrated.
Photochemistry and Reactivity of the Phenyl Radical–Water System: A Matrix Isolation and Computational Study
Authors: Mardyukov Artur , Crespo‐Otero Rachel , Sanchez‐Garcia Elsa , Sander Wolfram
Published: July 2010

The reaction of the phenyl radical 1 with water has been investigated by using matrix isolation spectroscopy and quantum chemical calculations. The primary thermal product of the reaction between 1 and water is a weakly bound complex stabilized by an OH⋅⋅⋅π interaction. This complex is photolabile, and visible‐light irradiation (λ>420 nm) results in hydrogen atom transfer from water to radical 1 and the formation of a highly labile complex between benzene and the OH radical. This complex is stable under the conditions of matrix isolation, however, continuous irradiation with λ>420 nm light results in the complete destruction of the aromatic system and formation of an acylic unsaturated ketene. The mechanisms of all reaction steps are discussed in the light of ab initio and DFT calculations.
Do Trinuclear Triplesalen Complexes Exhibit Cooperative Effects? Synthesis, Characterization, and Enantioselective Catalytic Sulfoxidation by Chiral Trinuclear FeIII Triplesalen Complexes
Authors: Mukherjee Chandan , Stammler Anja , Bögge Hartmut , Glaser Thorsten
Published: July 2010

The chiral triplesalen ligand H6chand provides three chiral salen ligand compartments in a meta‐phenylene arrangement by a phloroglucinol backbone. The two diastereomeric versions H6chandRR and H6chandrac have been used to synthesize the enantiomerically pure chiral complex [(FeCl)3(chandRR)] (3RR) and the racemic complex [(FeCl)3(chandrac)] (3rac). The molecular structure of the free ligand H6chandrac exhibits at the terminal donor sides the O‐protonated phenol–imine tautomer and at the central donor sides the N‐protonated keto–enamine tautomer. The trinuclear complexes are comprised of five‐coordinate square‐pyramidal FeIII ions with a chloride at the axial positions. The crystal structure of 3rac exhibits collinear chiral channels of ∼11 Å in diameter making up 33.6 % of the volume of the crystals, whereas the crystal structure of 3RR exhibits voids of 560 Å3. Mössbauer spectroscopy demonstrates the presence of FeIII high‐spin ions. UV/Vis spectroscopy is in accordance with a large delocalized system in the central backbone evidenced by strong low‐energy shifts of the imine π–π* transitions relative to that of the terminal units. Magnetic measurements reveal weak intramolecular exchange interactions but strong magnetic anisotropies of the FeIII ions. Complexes 3rac and 3RR are good catalysts for the sulfoxidation of sulfides providing very good yields and high selectivities with 3RR being enantioselective. A comparison of 3RR and [FeCl(salen′)] provides higher yields and selectivities but lower enantiomeric excess values (ee values) for 3RR relative to [FeCl(salen′)]. The low ee values of 3RR appeared to be connected to a strong ligand folding in 3RR, opening access to the catalytically active high‐valent Fe–O species. The higher selectivity is assigned to a cooperative stabilization of the catalytically active high‐valent Fe–O species through the phloroglucinol backbone in the trinuclear complexes.
Gold Catalysis: Tandem Reactions of Diyne–Diols and External Nucleophiles as an Easy Access to Tricyclic Cage‐Like Structures
Authors: Hashmi A. Stephen K. , Bührle Miriam , Wölfle Michael , Rudolph Matthias , Wieteck Marcel , Rominger Frank , Frey Wolfgang
Published: July 2010

Different diyne–diols composed of two terminal homopropargylic alcohol groups were prepared by bi‐directional synthesis. Subjection of the syn diastereomers to NAC–gold catalysts (NAC=nitrogen acyclic carbene) in the presence of external nucleophiles such as water or anilines provided substituted and highly rigid heterocyclic cages. The corresponding anti disastereomers polymerised. An intermediate of the reactions of the syn diastereomers could be isolated and even be characterised by crystal structure analysis. Overall, eight new bonds are formed in the reaction, which proceeds by a multistep sequence of highly selective hydroalkoxylations and hydrohydroxylation or hydroaminations. For furyl substituents and for internal alkynes competing reaction pathways could be identified. By the cross‐coupling of a product with an iodoaryl substituent, the use of these cage compounds as geometrically defined linking groups by using orthogonal transition‐metal‐catalysed methodology, namely, gold and palladium catalysis, could be demonstrated.
ChemInform Abstract: Synthesis of 5‐Aryl‐2‐[spiro‐(1,3‐dithiolane)‐2,4′‐(3′‐chloro‐2′‐azetidinone)‐1′‐yl] ‐1,3,4‐oxa(thia)diazoles and 5‐Aryl‐2‐[spiro‐(1,3‐dithiolane)‐2,2′‐(4′‐thiazolidinon)‐3′‐yl] ‐1,3,4‐oxa(thia)diazoles as Antimicrobial Agents.
Authors: KHAN M. H. , NIZAMUDDIN NIZAMUDDIN
Published: July 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Acid‐Catalyzed Condensation of Azulenes with 9‐Anthracenecarbaldehyde and the Synthesis of (9‐Anthryl)di(1‐azulenyl)methyl and (1‐Azulenyl)[10‐(1‐azulenyl)‐9‐anthryl]methyl Hexafluorophosphates.
Authors: Ito Shunji , Fujita Miwako , Morita Noboru , Asao Toyonobu
Published: July 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Synthesis of 1‐Amino‐ and 1‐Hydroxy‐9,10‐anthraquinone Derivatives Based on Reaction Sequences Between 2‐Acetyl‐1,4‐naphthoquinone and Enamines.
Authors: Kobayashi Kazuhiro , Uchida Masaharu , Watanabe Shinya , Takanohashi Atsushi , Tanmatsu Miyuki , Morikawa Osamu , Konishi Hisatoshi
Published: July 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: 1‐Deamino‐1(15)‐carba and ‐dicarba Analogues of Endothelin‐1
Authors: Hlavacek Jan , Marcova Renata , Budesinsky Milos , Slaninova Jirina
Published: July 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Arachno‐[Sn8]6‐ or closo‐[Li2Sn8]4‐? Synthesis and Characterization of A4Li2Sn8 (A: Rb, K).
Authors: Bobev Svilen , Sevov Slavi C.
Published: July 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: The Structure of the FeIVO4‐4 Ion.
Authors: Weller Mark T. , Hector Andrew L.
Published: July 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Specific Inhibitors of the Breast Cancer Resistance Protein (BCRP)
Authors: Pick Anne , Klinkhammer Werner , Wiese Michael
Published: July 2010

A new class of specific breast cancer resistance protein (BCRP) inhibitors was identified, showing no inhibition of the ATP binding cassette (ABC) transporters P‐gp and MRP1. Some of these modulators inhibit BCRP with high potency; they are only slightly less potent than Ko143 and could serve as promising lead structures for the design of novel effective BCRP inhibitors. These inhibitors are structurally related to tariquidar (XR9576) and belong to a library of multidrug‐resistance modulators synthesized by our research group. The absence of the tetrahydroisoquinoline substructure appears to play a crucial role for specificity; we found that the presence of this substructure is not essential for interaction with BCRP. To determine the type of interaction between pheophorbide A and compounds with and without the tetrahydroisoquinoline substructure, various substrate pheophorbide A concentrations were used in enzyme kinetics assays. The resulting data show that these compounds share a noncompetitive‐type interaction with pheophorbide A. Experiments with imatinib and pheophorbide A revealed a mixed‐type interaction. The combination of imatinib and compounds with and without the tetrahydroisoquinoline substructure resulted in a positive cooperative effect, indicating that imatinib engages a binding site distinct from that of the new compounds on one side and distinct from that of pheophorbide A on the other side as well. The results of this study suggest that the category of BCRP‐specific inhibitors, which includes only fumitremorgin C, Ko143 and analogues, and novobiocin needs to be extended by this new class of inhibitors, which possess three key characteristics: specificity, potency, and low toxicity.
Quantum‐Dot‐Sensitized Solar Cells
Authors: Rühle Sven , Shalom Menny , Zaban Arie
Published: July 2010

Quantum‐dot‐sensitized solar cells (QDSCs) are a promising low‐cost alternative to existing photovoltaic technologies such as crystalline silicon and thin inorganic films. The absorption spectrum of quantum dots (QDs) can be tailored by controlling their size, and QDs can be produced by low‐cost methods. Nanostructures such as mesoporous films, nanorods, nanowires, nanotubes and nanosheets with high microscopic surface area, redox electrolytes and solid‐state hole conductors are borrowed from standard dye‐sensitized solar cells (DSCs) to fabricate electron conductor/QD monolayer/hole conductor junctions with high optical absorbance. Herein we focus on recent developments in the field of mono‐ and polydisperse QDSCs. Stability issues are adressed, coating methods are presented, performance is reviewed and special emphasis is given to the importance of energy‐level alignment to increase the light to electric power conversion efficiency.
Metal‐Enhanced Fluorescence of CdTe Nanocrystals in Aqueous Solution
Authors: Li Rongqing , Xu Shuhong , Wang Chunlei , Shao Haibao , Xu Qinying , Cui Yiping
Published: July 2010

Metal‐enhanced fluorescence of semiconductor nanocrystals (NCs) is investigated. There is very little attention paid to the metal‐enhanced fluorescence in aqueous solution, which has great potential applications in bioscience. In this work, we directly observe metal‐enhanced fluorescence of CdTe NC solution by simply mixing CdTe NCs and Au nanoparticles, both of which are negatively charged. In order to study this kind of photoluminescence enhancement in aqueous solutions, we propose a calibration method, which takes into account the light attenuation in solutions. After consideration of the light weakening in transmission, the maximal PL enhancement is about 3 times as large as the ones without Au NPs. Some factors related to the enhanced magnitude of fluorescence, for instance, the concentration and the molar feed ratio of CdTe NCs and Au NPs, are studied in detail. Furthermore, the decreased lifetimes of CdTe NCs induced by Au NPs are also obtained, which are in accord with the enhancement of the photoluminescence.
Asymmetry and Non‐Adiabaticity in Fragmentation of Disulfide Bonds upon Electron Capture
Authors: Gámez José A. , Serrano‐Andrés Luis , Yáñez Manuel
Published: July 2010

Although it has been generally assumed that electron attachment to disulfide derivatives leads to a systematic and significant activation of the SS bond, we show, by using [CH3SSX] (X=CH3, NH2, OH, F) derivatives as model compounds, that this is the case only when the X substituents have low electronegativity. Through the use of MP2, QCI and CASPT2 molecular orbital (MO) methods, we elucidate, for the first time, the mechanisms that lead to unimolecular fragmentation of disulfide derivatives after electron attachment. Our theoretical scrutiny indicates that these mechanisms are more intricate than assumed in previous studies. The most stable products, from a thermodynamic viewpoint, correspond to the release of neutral molecules; CH4, NH3, H2O, and HF. However, the barriers to reach these products depend strongly on the electronegativity of the X substituents. Only for very electronegative substituents, such as OH or F, the loss of H2O or HF is the most favorable process, and likely the only one observed. This is possible because of two concomitant factors, 1) the extra electron for [CH3SSX]− (X=OH, F) occupies a σ*(SX) MO, which favors the cleavage of the SX bond, and 2) the activation barriers associated with the hydrogen transfer process to produce H2O and HF are rather low. Only when the substituents are less electronegative (X=H, CH3, NH2) the extra electron is located in a σ*(SS) orbital and the cleavage of the disulfide bridge becomes the most favorable process. The intimate mechanism associated with the SS bond dissociation process also depends strongly on the nature of the substituent. For X=H or CH3 the process is strictly adiabatic, while for X=NH2 it proceeds through a conical intersection (CI) associated with the charge reorganization necessary to obtain, from a molecular anion with the extra electron delocalized in a σ*(SS) antibonding orbital, two fragments with the proper charge localization.
Post‐stroke depression: the case for augmented, individually tailored cognitive behavioural therapy
Authors: Broomfield Niall M. , Laidlaw Ken , Hickabottom Emma , Murray Marion F. , Pendrey Rachel , Whittick Janice E. , Gillespie David C.
Published: July 2010

In this review, we begin by considering why post‐stroke depression (PSD) is so prevalent. We then examine the current evidence base to support cognitive behavioural therapy (CBT) as a treatment approach for the condition. While there is limited evidence currently, we demonstrate that much remains to be established with regard to PSD and the efficacy of CBT. We argue there is every reason to believe CBT should be an effective treatment, but that clinicians must augment and individually tailor this approach to ensure effectiveness. We set out our rationale for a novel augmented, individually tailored CBT protocol, and describe five key components that we believe once incorporated, and tested using randomized controlled methods, should enhance treatment outcome of PSD. Copyright © 2010 John Wiley & Sons, Ltd.

Key Practitioner Message:

• Depression is a common consequence of stroke.

• Despite a lack of clear evidence, there is reason to believe cognitive behavioural therapy (CBT) for post‐stroke depression should be effective, if it is adapted and tailored to the specific needs of stroke survivors.

• Augmented and individually tailored therapy using motivational interviewing techniques, grief resolution, selection optimization compensation, cognitive deficits adaptations and executive skills training is recommended.

• It is important to individualize augmented CBT, based on principles of case formulation.
Growth and characterization of calcium hydrogen phosphate dihydrate crystals from single diffusion gel technique
Authors: Rajendran K. , Dale Keefe C.
Published: July 2010

Calcium hydrogen phosphate dihydrate (CaHPO4·2H2O, CHPD) a dissolved mineral in urine is known to cause renal or bladder stones in both human and animals. Growth of CHPD or brushite using sodium metasilicate gel techniques followed by light and polarizing microscopic studies revealed its structural and morphological details. Crystal identity by powder x‐ray diffraction confirmed the FT‐IR and FT‐Raman spectroscopic techniques as alternate methods for fast analysis of brushite crystals which could form as one type of renal stones. P‐O‐P asymmetric stretchings in both FT‐IR (987.2, 874.1 and 792 cm‐1) and FT‐Raman (986.3 cm‐1, 1057.6 cm‐1 and 875.2 cm‐1) were found as characteristics of brushite crystals. Differential Scanning Calorimetry (DSC) analysis revealed brushite crystallization purity using gel method by studying their endothermic peaks. This study incorporated a multidisciplinary approach in characterizing CHPD crystals grown in vitro to help formulate prevention or dissolution strategy in controlling urinary stone growth. Initial studies with 0.2 M citric acid ions as controlling agent in the nucleation of brushite crystals further support the presented approach. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of Ba ions substitution on multiferroic properties of BiFeO3 perovskite
Authors: Gautam A. , Rangra V. S.
Published: July 2010

Dielectric, magnetic and ferroelectric properties of Bi1‐xBaxFeO3(x = 0.1, 0.2 and 0.3) synthesized by solid state reaction method are reported. X‐ray diffraction pattern showed that Bi1‐xBaxFeO3was single phase. Ba substitution has led to a decrease in grain size and hence an increase in the electrical resistivity. The variation of dielectric constant and loss has been studied over a frequency range of 1 kHz – 2 MHz at room temperature. Ba doping leads to effective suppression of the spiral spin structure of BiFeO3, resulting in the appearance of net magnetization. Improved multiferroic properties of Bi0.8Ba0.2FeO3 ceramic with remnant magnetization and polarization 0.093 emu/g and 0.808 µC/cm2, respectively, were obtained. The evidence of ferromagnetism and ferroelectric hysteresis loops in Bi1‐xBaxFeO3system at room temperature makes it a good candidate for potential applications. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Efficient multi‐threshold voltage techniques for minimum leakage current in nanoscale technology
Authors: Rjoub Abdoul , Al‐Ajlouni Motasem
Published: July 2010

The influence of multi‐threshold voltage technique on reducing the leakage power in CMOS circuits at transistor level based on Nanoscale SPICE parameters is investigated in this paper. Based on Artificial Intelligence search algorithms, three new algorithms are proposed to determine the exact threshold voltage for each transistor in order to minimize the leakage current at lowest value. These algorithms are: Slack Time Search Algorithm (STS), Leakage Power Search Algorithm (LPS), Leakage and Slack Time Search Algorithm (LSS). As a result, 70% of sub‐threshold leakage current is reduced without degrading the performance. Based on 22 nm predictive SPICE parameters proposed by BSIM4, simulation results verified the validity of the proposed algorithms. Copyright © 2010 John Wiley & Sons, Ltd.
Generation of current mode filters using NAM expansion
Authors: Soliman Ahmed M.
Published: July 2010

Systematic synthesis method to generate a family of current mode band‐pass–low‐pass circuits based on nodal admittance matrix (NAM) expansion is given. Eight equivalent circuits are obtained, five of them are new. Each of the generated circuits uses two grounded capacitors and three grounded resistors and two balanced output current conveyor (BOCCII) or two balanced output inverting current conveyor (BOICCII) or a combination of the two types. Generation of a low input impedance current mode band‐pass–low‐pass circuits based on NAM expansion results in 16 equivalent circuits. The NAM expansion is also used to generate 32 equivalent current mode universal filters using four BOCCII or BOICCII or a combination of the two types. Copyright © 2010 John Wiley & Sons, Ltd.
Two‐switch flyback PWM DC‐DC converter in continuous‐conduction mode
Authors: Murthy‐Bellur Dakshina , Kazimierczuk Marian K.
Published: July 2010

The two‐switch flyback DC‐DC converter is an extended version of the conventional single‐switch flyback converter. An additional switch and two clamping diodes serve as a simple, but an effective way to limit the switch overvoltages, which occur in the conventional single‐switch flyback converter due to the ringing of the resonant circuit formed by the transformer leakage inductance and the transistor output capacitance. The clamping diodes in the two‐switch flyback topology clamp the maximum voltage across each switch equal to the DC input voltage. This paper presents a detailed steady‐state analysis and design procedure of the diode‐clamped two‐switch flyback converter operated in continuous‐conduction mode (CCM). The power loss in each component of the two‐switch flyback converter is compared with those of the single‐switch flyback converters with and without RCD clamp, and is presented in a tabular form. The two‐switch flyback converter was bread‐boarded to validate the theoretical analysis. Experimental results from a 10 V/30 W, 100 kHz laboratory prototype verified that the maximum switch voltage is limited to the DC input voltage. Copyright © 2010 John Wiley & Sons, Ltd.
Cell type–specific expression of adenomatous polyposis coli in lung development, injury, and repair
Authors: Li Aimin , Xing Yiming , Chan Belinda , Heisterkamp Nora , Groffen John , Borok Zea , Minoo Parviz , Li Changgong
Published: July 2010

Adenomatous polyposis coli (Apc) is critical for Wnt signaling and cell migration. The current study examined Apc expression during lung development, injury, and repair. Apc was first detectable in smooth muscle layers in early lung morphogenesis, and was highly expressed in ciliated and neuroendocrine cells in the advanced stages. No Apc immunoreactivity was detected in Clara or basal cells, which function as stem/progenitor cell in adult lung. In ciliated cells, Apc is associated mainly with apical cytoplasmic domain. In response to naphthalene‐induced injury, Apcpositive cells underwent squamous metaplasia, accompanied by changes in Apc subcellular distribution. In conclusion, both spatial and temporal expression of Apc is dynamically regulated during lung development and injury repair. Differential expression of Apc in progenitor vs. nonprogenitor cells suggests a functional role in cell‐type specification. Subcellular localization changes of Apc in response to naphthalene injury suggest a role in cell shape and cell migration. Developmental Dynamics 239:2288–2297, 2010. © 2010 Wiley‐Liss, Inc.
Expression of the Zebrafish CD133/prominin1 Genes in Cellular Proliferation Zones in the Embryonic Central Nervous System and Sensory Organs
Authors: McGrail Maura , Batz Lindsey , Noack Kristin , Pandey Saumya , Huang Yong , Gu Xun , Essner Jeffrey J.
Published: July 2010

Expression pattern of the zebrafish CD133/prominin1a gene in the 36 hour post fertilization embryo. prominin1a is expressed in the lens in the eye and in the ventricular zone on the ventral side of the midbrain tegmentum. From McGrail et al., Developmental Dynamics 239:1849–1857, 2010
Fixing an irrelevant TCRα chain reveals the importance of TCRβ diversity for optimal TCRαβ pairing and function of virus‐specific CD8+ T cells
Authors: Valkenburg Sophie A. , Day E. Bridie , Swan Natasha G. , Croom Hayley A. , Carbone Francis R. , Doherty Peter C. , Turner Stephen J. , Kedzierska Katherine
Published: July 2010

TCR repertoire diversity can influence the efficacy of CD8+ T‐cell populations, with greater breadth eliciting better protection. We analyzed TCRβ diversity and functional capacity for influenza‐specific CD8+ T cells expressing a single TCRα chain. Mice (A7) transgenic for the H2KbOVA257–264‐specific Vα2.7 TCR were challenged with influenza to determine how fixing this “irrelevant” TCRα affects the “public” and restricted DbNPCD8+ versus the “private” and diverse DbPACD8+ responses. Though both DbNPCD8+ and DbPACD8+ sets are generated in virus‐primed A7 mice, the constrained DbNPCD8+ population lacked the characteristic, public TCRVβ8.3, and consequently was reduced in magnitude and pMHC‐I avidity. For the more diverse DbPACD8+ T cells, this particular forcing led to a narrowing and higher TCRβ conservation of the dominant Vβ7, though the responses were of comparable magnitude to C57BL/6J controls. Interestingly, although both the TCRβ diversity and the cytokine profiles were reduced for the DbNPCD8+ and DbPACD8+ sets in spleen, the latter measure of polyfunctionality was comparable for T cells recovered from the infected lungs of A7 and control mice. Even “sub‐optimal” TCRαβ pairs can operate effectively when exposed in a milieu of high virus load. Thus, TCRβ diversity is important for optimal TCRαβ pairing and function when TCRα is limiting.
Synthesis, Structure, Characterization, and Redox Properties of the Porous MIL‐68(Fe) Solid
Authors: Fateeva Alexandra , Horcajada Patricia , Devic Thomas , Serre Christian , Marrot Jérôme , Grenèche Jean‐Marc , Morcrette Mathieu , Tarascon Jean‐Marie , Maurin Guillaume , Férey Gérard
Published: July 2010

A new porous FeIII‐based MOF, formulated Fe(OH)(BDC)·(dmf)x with x ≈ 1.1 and presenting the MIL‐68 topology, was prepared by reaction of an iron(III) salt and terephthalic acid (H2BDC) in N,N′‐dimethylformamide (dmf) under acidic conditions. The structure and properties of this solid were studied by means of X‐ray diffraction, thermogravimetric analysis, nitrogen sorption, 57Fe Mössbauer spectrometry, and electrochemical lithium insertion.
Experimental and Theoretical Investigation of the Enantiomerization of Lithium α‐tert‐Butylsulfonyl Carbanion Salts and the Determination of Their Structures in Solution and in the Crystal
Authors: Scholz Roland , Hellmann Gunther , Rohs Susanne , Raabe Gerhard , Runsink Jan , Özdemir Diana , Luche Olaf , Heß Thomas , Giesen Alexander W. , Atodiresei Juliana , Lindner Hans J. , Gais Hans‐Joachim
Published: July 2010

Dynamic NMR (DNMR) spectroscopy of [R1C(R2)SO2R3]Li (R1, R2 = alkyl, phenyl; R3 = Ph, tBu, adamantyl, CEt3) in [D8]THF has shown that the S‐tBu, S‐adamantyl, and S‐CEt3 derivatives have a significantly higher enantiomerization barrier than their S‐Ph analogues. Cα–S bond rotation is most likely the rate‐determining step of the enantiomerization of the salts bearing a bulky group at the S atom and two substituents at the Cα atom. Ab initio calculations on [Me(Ph)SO2tBu]– gave information about the two Cα–S rotational barriers, which are dominated by steric effects. Cryoscopy of [R1C(R2)SO2tBu]Li in THF at –108 °C revealed the existence of monomers and dimers. X‐ray crystal structure analysis of the monomers and dimers of [R1C(R2)SO2tBu]Li·Ln (R1 = Me, Et, tBuCH2, PhCH2, tBu; R2 = Ph, L = THF, 12‐crown‐4, PMDTA) and [R1C(R2)SO2Ph]Li·2diglyme [R1 = R2 = Me, Et; R1–R2 = (CH2)5] showed them to be O–Li contact ion pairs (CIPs). The monomers and dimers have a Cα–S conformation in which the lone‐pair orbital at the Cα atom bisects the O–S–O angle and a significantly shortened Cα–S bond. The Cα atom of [R1C(R2)SO2R3]Li·Ln (R1 = Ph; R3 = Ph, tBu) is planar, whereas the Cα atom of [R1C(R2)SO2R3]Li·Ln (R1 = R2 = alkyl) is strongly pyramidalized in the case of R3 = Ph and most likely planar for R3 = tBu. Ab initio calculations on [MeC(Me)SO2R]– gave a pyramidalized Cα atom for R = Me and a nearly planar one for R = CF3 and tBu. The [R1C(R2)SO2tBu]Li salts were characterized by 1H, 13C, and 6Li NMR spectroscopy. 1H{1H} and 6Li{1H} NOE experiments are in accordance with the existence of O–Li CIPs. 1H and 13C NMR spectroscopy of [R1C(R2)SO2tBu]Li in [D8]THF at low temperatures showed equilibrium mixtures of up to five different species being most likely monomeric and dimeric O–Li CIPs with different configurations. According to 7Li NMR spectroscopy, the addition of HMPA to [MeC(Ph)SO2tBu]Li in [D8]THF at low temperatures causes the formation of the separated ion pair [MeC(Ph)SO2tBu]Li(HMPA)4.
Wirkungsvoll bis ins hohe Alter
Authors: Berger Christina
Published: July 2010

Fossil betriebene Kraftwerke bleiben wichtige Bausteine moderner Energieversorgung. Auch die neuesten Anlagen sind auf mindestens 30 Jahre ausgelegt. Sie sollen die Wärme noch besser und sauberer in Energie umwandeln. Wissenschaft und Wirtschaft entwickeln dafür innovative Bauteile. Ihre Vision: Kraftwerke mit „Nahe‐Null‐Emmission”︁
Chronik einer missachteten Gewissheit
Authors: Rahmstorf Stefan
Published: July 2010

Schon seit 150 Jahren kennen Wissenschaftler den Treibhauseffekt. Ausmaß und Folgen der Erderwärmung werden seitdem immer genauer beschrieben. Doch Politik, Wirtschaft und Gesellschaft haben alle Warnungen nicht ernst genug genommen. Heute sind die Optionen für eine klimafreundlichere Gewinnung und Nutzung von Energie klarer denn je – aber die Zeit für ihre Umsetzung läuft davon.
Die Gasometer von morgen
Authors: Schüth Ferdi
Published: July 2010

Regenerative Energie steht weder ständig noch gleichmäßig zur Verfügung – sie zu speichern, wird deshalb immer wichtiger. Solarthermische Kraftwerke, Metall‐Luft‐Batterien oder energiereiche chemische Verbindungen wie Methan bieten langfristig Große Potenziale. Vorerst sind sie vor allem eine Herausforderung für die Forschung.
Der selbstsüchtige Energiefresser im Kopf
Authors: Peters Achim
Published: July 2010

Auch für den menschlichen Organismus sind Störungen im Energiekreislauf eine Gefahr: Wenn das Gehirn seinen Glukosebedarf aus dem Körper nicht decken kann, gibt es den Befehl zu sofortiger Nahrungsaufnahme – Übergewicht und Diabetes können die Folge sein.
Management of chronic pain: current and future options
Authors: Searle Robert , Simpson Karen
Published: July 2010

Chronic pain is surprisingly prevalent and, if left untreated, can lead to significant limitations for the sufferer including restricted mobility and possible job loss. Pain has also been shown to be the reason for 40% of patient visits to GPs each year. This results in a substantial economic burden not only for those involved but also for the wider economy. Here we review the current options for pain management and look at new treatments in the pipeline. Copyright © 2010 John Wiley & Sons, Ltd.
Pseudocapacitive Properties of Nano‐structured Anhydrous Ruthenium Oxide Thin Film Prepared by Electrostatic Spray Deposition and Electrochemical Lithiation/Delithiation
Authors: Park S.‐H. , Kim J.‐Y. , Kim K.‐B.
Published: July 2010

Nano‐structured anhydrous ruthenium oxide (RuO2) thin films were prepared using an electrostatic spray deposition (ESD) technique followed by electrochemical lithiation and delithiation. During the electrochemical lithiation process, RuO2 decomposed to nano‐structured metallic ruthenium Ru with the concomitant formation of Li2O. Nano‐structured RuO2 was formed upon subsequent electrochemical extraction of Li from the Ru/Li2O nanocomposite. Electrochemical lithiation/deliathiation at different charge/discharge rates (C‐rate) was used to control the nano‐structure of the anhydrous RuO2. Electrochemical lithiation/delithiation of the RuO2 thin film electrode at different C‐rates was closely related to the specific capacitance and high rate capability of the nano‐structured anhydrous RuO2 thin film. Nano‐structured RuO2 thin films prepared by electrochemical lithiation and delithiation at 2C rate showed the highest specific capacitance of 653 F g–1 at 20 mV s–1, which is more than two times higher than the specific capacitance of 269 F g–1 for the as‐prepared RuO2. In addition, it showed 14% loss in specific capacitance from 653 F g–1 at 20 mV s–1 to 559 F g–1 at 200 mV s–1, indicating significant improvement in the high rate capability compared to the 26% loss of specific capacitance of the as‐prepared RuO2 electrode from 269 F g–1 at 20 mV s–1 to 198 F g–1 at 200 mV s–1 for the same change in scan rate.
Performance comparison of ZnO photocatalyst in various reactor systems
Authors: Akyol Abdurrahman , Bayramoglu Mahmut
Published: July 2010

BACKGROUND:

Owing to difficulties in catalyst recovery from slurries the deposition of a catalyst on suitable supports has been investigated extensively in recent years. The support material and the method of coating influence the activity. Photocatalytic decolorization of methyl orange (MO) and Rem Red F3B (RRF3B) was conducted in various reactor systems including a slurry reactor, ZnO thin film coated tube reactor and fixed bed reactor filled with ZnO coated ceramic or glass supports of various geometries.

RESULTS:

ZnO coating was carried out by the ammonium zincate deposition method. ZnO thin films were quite stable in acidic and basic media and resistant to photocorrosion. Various methods including scanning electron microscopy (SEM) and X‐ray diffraction (XRD) were applied for the physical characterization of thin films. The XRD patterns of ZnO thin film exhibit a wurtzite (zincite) crystal structure. SEM analysis revealed the granular morphology of ZnO film with a particle size of 300–400 nm.

CONCLUSION:

Photocatalytic activities were determined kinetically by calculating first‐order rate constants, which were also related to process variables by regression analysis. From the viewpoint of decolorization efficiency, the coated tube reactor (6 mm i.d.) showed the highest activity, which was equal to that of a powder catalyst loading of 300 mg dm−3 for MO and of 200 mg dm−3 for RRF3B. Copyright © 2010 Society of Chemical Industry