bluuebunny/crossref_metadata_2025 huggingface dataset:
In vivo assessment of amyloid‐β deposition in nondemented very elderly subjects
Authors: Mathis Chester A. , Kuller Lewis H. , Klunk William E. , Snitz Beth E. , Price Julie C. , Weissfeld Lisa A. , Rosario Bedda L. , Lopresti Brian J. , Saxton Judith A. , Aizenstein Howard J. , McDade Eric M. , Kamboh M. Ilyas , DeKosky Steven T. , Lopez Oscar L.
Published: November 2012

Objective

This study examined amyloid‐β (Aβ) deposition in 190 nondemented subjects aged ≥82 years to determine the proportion of Aβ‐positive scans and associations with cognition, apolipoprotein E (APOE) status, brain volume, and Ginkgo biloba (Gb) treatment.

Methods

Subjects who agreed to participate had a brain magnetic resonance imaging and positron emission tomography scan with 11C‐labeled Pittsburgh compound B (PiB) following completion of a Gb treatment clinical trial. The youngest subject in this imaging study was 82 years, and the mean age of the subjects was 85.5 years at the time of the scans; 152 (80%) were cognitively normal, and 38 (20%) were diagnosed with mild cognitive impairment (MCI) at the time of the PiB study.

Results

A high proportion of the cognitively normal subjects (51%) and MCI subjects (68%) were PiB‐positive. The APOE*4 allele was more prevalent in PiB‐positive than in PiB‐negative subjects (30% vs 6%). Measures of memory, language, and attentional functions were worse in PiB‐positive than in PiB‐negative subjects, when both normal and MCI cases were analyzed together; however, no significant associations were observed within either normal or MCI subject groups alone. There was no relationship between Gb treatment and Aβ deposition as determined by PiB.

Interpretation

The data revealed a 55% prevalence of PiB positivity in nondemented subjects age >80 years and 85% PiB positivity in the APOE*4 nondemented elderly subjects. The findings also showed that long‐term exposure to Gb did not affect the prevalence of cerebral Aβ deposition. ANN NEUROL 2013;73:751–761
Diffusion changes predict cognitive and functional outcome: The LADIS study
Authors: Jokinen Hanna , Schmidt Reinhold , Ropele Stefan , Fazekas Franz , Gouw Alida A. , Barkhof Frederik , Scheltens Philip , Madureira Sofia , Verdelho Ana , Ferro José M. , Wallin Anders , Poggesi Anna , Inzitari Domenico , Pantoni Leonardo , Erkinjuntti Timo ,   LADIS Study Group
Published: November 2012

Objective

A study was undertaken to determine whether diffusion‐weighted imaging (DWI) abnormalities in normal‐appearing brain tissue (NABT) and in white matter hyperintensities (WMH) predict longitudinal cognitive decline and disability in older individuals independently of the concomitant magnetic resonance imaging (MRI) findings.

Methods

A total of 340 LADIS (Leukoaraiosis and Disability Study) participants, aged 65 to 84 years, underwent brain MRI including DWI at baseline. Neuropsychological and functional assessments were carried out at study entry and repeated annually over a 3‐year observational period. Linear mixed models and Cox regression survival analysis adjusted for demographics, WMH volume, lacunes, and brain atrophy were used to evaluate the independent effect of the DWI measures on change in cognitive performance and functional abilities.

Results

The mean global apparent diffusion coefficient (ADC) and the relative peak height and peak position of the ADC histogram in NABT predicted faster rate of decline in a composite score for speed and motor control. Higher mean ADC and lower peak height were also related to deterioration in executive functions and memory (specifically working memory), with peak height also being related to more rapid transition to disability and higher rate of mortality. Mean ADC in WMH had less pronounced effects on cognitive and functional outcomes.

Interpretation

DWI microstructural changes in NABT predict faster decline in psychomotor speed, executive functions, and working memory regardless of conventional MRI findings. Moreover, these changes are related to functional disability and higher mortality. Ann Neurol 2013;73:576–583
Overinhibition of corticostriatal activity following prenatal cocaine exposure
Authors: Wang Wengang , Nitulescu Ioana , Lewis Justin S. , Lemos Julia C. , Bamford Ian J. , Posielski Natasza M. , Storey Granville P. , Phillips Paul E. M. , Bamford Nigel S.
Published: November 2012

Objective

Prenatal cocaine exposure (PCE) can cause persistent neuropsychological and motor abnormalities in affected children, but the physiological consequences of PCE remain unclear. Conclusions drawn from clinical studies can sometimes be confounded by polysubstance abuse and nutritional deprivation. However, existing observations suggest that cocaine exposure in utero, as in adults, increases synaptic dopamine and promotes enduring dopamine‐dependent plasticity at striatal synapses, altering behaviors and basal ganglia function.

Methods

We used a combination of behavioral measures, electrophysiology, optical imaging, and biochemical and electrochemical recordings to examine corticostriatal activity in adolescent mice exposed to cocaine in utero.

Results

We show that PCE caused abnormal dopamine‐dependent behaviors, including heightened excitation following stress and blunted locomotor augmentation after repeated treatment with amphetamine. These abnormal behaviors were consistent with abnormal γ‐aminobutyric acid (GABA) interneuron function, which promoted a reversible depression in corticostriatal activity. PCE hyperpolarized and reduced tonic GABA currents in both fast‐spiking and persistent low‐threshold spiking type GABA interneurons to increase tonic inhibition at GABAB receptors on presynaptic corticostriatal terminals. Although D2 receptors paradoxically increased glutamate release following PCE, normal corticostriatal modulation by dopamine was reestablished with a GABAA receptor antagonist.

Interpretation

The dynamic alterations at corticostriatal synapses that occur in response to PCE parallel the reported effects of repeated psychostimulants in mature animals, but differ in being specifically generated through GABAergic mechanisms. Our results indicate approaches that normalize GABA and D2 receptor‐dependent synaptic plasticity may be useful for treating the behavioral effects of PCE and other developmental disorders that are generated through abnormal GABAergic signaling. ANN NEUROL 2013;73:355–369
Synthese und Anwendung wasserlöslicher NHC‐Übergangsmetall‐Komplexe
Authors: Schaper Lars‐Arne , Hock Sebastian J. , Herrmann Wolfgang A. , Kühn Fritz E.
Published: November 2012

Dieser Aufsatz gibt eine Übersicht über Übergangsmetallkomplexe mit wasserlöslichen NHC‐Liganden. Bekannte Routen zur Einführung von Wasserlöslichkeit durch gezieltes Ligandendesign werden beleuchtet, und einige allgemeine Eigenschaften wasserlöslicher NHC‐Komplexen werden diskutiert. Die erhöhte Hydrophilie wasserlöslicher Katalysatoren bietet zusätzliche Vorteile für Anwendungen in der Synthese. Neben klassischen Umsetzungen, wie z. B. C‐C‐Kupplungen, umfassen neuere Beispiele von Katalysen mit wasserlöslichen NHC‐Komplexen auch Metathesen und Hydrierungen, in denen sich diese Katalysatoren als besonders leistungsfähig erweisen. Insgesamt ist das Gebiet in weiten Teilen noch unerforscht und hat daher ein großes Potenzial für zukünftige Forschung.
Improvement of the adhesion properties of silicone rubber by the incorporation of silane‐modified montmorillonite
Authors: Kim Eung Soo , Kim Eun Jeong , Lee Tae Hwa , Yoon Jin San
Published: November 2012

A silicone rubber precursor was amended by the incorporation of γ‐aminopropyl triethoxysilane (APS) into siloxane to prepare an elastomeric thermal insulator adhering to the isocyanate‐group‐containing liner sheets, which are actually used to envelop rocket propellants. This improved adhesion may protect the liners of the rocket motor cases efficiently against the hot combustion gas. Clay was modified by cationic exchange with an amine compound, and the resulting clay was further treated with APS and N‐(2‐aminoethyl)‐3‐aminopropyl trimethoxysilane to introduce amine groups onto the surface of the clay to further improve the adhesion of the silicone rubber to the liner. The neat and modified clays were compounded with the APS‐amended silicone rubber [room‐temperature vulcanizate (RTV)]. The effects of the clay modification on the adhesion properties were explored. The peel strength between the liner and the room‐temperature silicone rubber (RTV) based on siloxane was 0, whereas the peel strength increased to 3.7 N/cm when the silicone rubber was amended with APS. The peel strength between APS–RTV and the liner was lower than 3.7 N/cm when clay was added, whereas the peel strength became higher than 5.7 N/cm so that APS–RTV could not withstand the peeling force and was torn off before the delamination when the amine silane modified clay was added instead of clay. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Sunflower‐oil‐based lecithin organogels as matrices for controlled drug delivery
Authors: Satapathy D. , Biswas D. , Behera B. , Sagiri S. S. , Pal K. , Pramanik K.
Published: November 2012

In this study, we dealt with the development of lecithin‐based organogels using sunflower oil as the apolar phase. Metronidazole (MZ) was used as a model drug. The organogels were characterized by microscopy (light and phase contrast), Fourier transform infrared spectroscopy, X‐ray diffraction, differential scanning calorimetry, rheology, alternating‐current impedance, hemocompatibility, antimicrobial analysis, and in vitro drug release. Microscopic analysis revealed the presence of spherical reverse micellar structures. There was an increase in the intermolecular hydrogen bonding among the gel components and crystallinity as MZ was incorporated into the organogels. The pH of the gel indicated that the gel may be nonirritant in nature and was hemocompatible. The release of MZ from the organogels followed Higuchi kinetics and was governed by anomalous or non‐Fickian transport. The drug‐loaded organogels showed antimicrobial activity against Bacillus subtilis, a Gram‐positive bacteria. The preliminary results indicate that the developed organogel may be used as drug‐delivery vehicle. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Preparation and characterization of bacterial cellulose microfiber/goat bone apatite composites for bone repair
Authors: Fan Xiaoxia , Zhang Tingting , Zhao Zhitong , Ren Haohao , Zhang Qiyi , Yan Yonggang , Lv Guoyu
Published: November 2012

Bacterial cellulose (BC) and goat bone apatite (GBA) composites were fabricated by a dissolving method. The 4‐methylmorpholine‐4‐oxide (NMMO) served as the solvent for BC. Goat bone apatite was added to the NMMO solution of BC, so the shape of the material could be easily controlled by using appropriate molds. The expected composites were fabricated from NMMO by immersion in water‐bath and formed by lyophilization. The results indicated that GBA was homogenously distributed into BC matrix and some interaction formed at the interface between BC and GBA. The crystallinity of BC in the composites decreased with the increase of GBA content. And the weight loss ratio of the composites decreased with the increase of GBA content and the degradation rate of BC/GBA composites could be adjusted by changing the GBA content in the composites. The surface, after soaking in PBS, was suitable for cell growth. The pH value of the medium was stable around 7.38 after the composites were immersed into PBS for 12 weeks, which was beneficial to bone cell differentiation. Furthermore, the MTT test results showed BC/GBA composites could stimulate cell proliferation and promote the cell differentiation. The results demonstrated that the prepared BC/GBA biocomposite could be a promising bone filler material for bone defects repair and construction. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Application of lignin‐modified phenolic resins to brake friction material
Authors: Kuroe Motoki , Tsunoda Tomoki , Kawano Yusuke , Takahashi Akio
Published: November 2012

Lignin‐modified phenolic resin (LPF) is prepared from methanol‐soluble lignin by polymer blend methods (solvent blend and in situ polymerization) for application to environment‐friendly brake friction material. The chemical structure of LPF is characterized by 13C NMR, and TMA and DSC analyses are conducted to evaluate the thermal behaviors. Flexural tests and brake dynamometer tests of samples prepared from LPF by compression molding are carried out, and the results are compared with those for the samples prepared from commercial phenolic resin (PF). Results of the flexural test show that the addition of methanol‐soluble lignin by solvent blend polymerization decreases the flexural strength. In contrast, in situ polymerized LPF exhibits flexural strength equivalent to that of PF. Results of the brake dynamometer test show that replacement of PF with methanol‐soluble lignin increases the fade resistance of the brake friction material at elevated temperatures. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Global Optimal Feedback‐Linearizing Control of Robot Manipulators
Authors: Chatraei Abbas , Záda Vaclav
Published: November 2012

The present paper offers a new optimal feedback‐linearizing control scheme for robot manipulators. The method presented aims at solving a special form of the unconstrained optimal control problem (OCP) of robot manipulators globally using the results of the Lyaponov method and feedback‐linearizing strategy and without using the calculus of variations (indirect method), direct methods, or the dynamic programming approach. Most of these methods and their sub‐branches yield a local optimal solution for the considered OCP by satisfying some necessary conditions to find the stationary point of the considered cost functional. In addition, the proposed method can be used for both set‐point regulating (point‐to‐point) tasks (e.g. pick‐and‐place operation or spot welding tasks) and trajectory tracking tasks such as painting or welding tasks. However, the proposed method can not support the physical constraints on robot manipulators and requires precise dynamics of the robot, as well. Instead, it can be used as an on‐line optimal control algorithm which produces the optimal solution without performing any kind of optimization algorithms which require time to find the optimal solution.
Lack of differences in the pharmacokinetics of sepantronium bromide (YM155) between US and Japanese patients with advanced solid tumors or non‐Hodgkin lymphoma
Authors: Aoyama Yumiko , Katashima Masataka , Sawamoto Taiji
Published: November 2012

The analysis was designed to compare the pharmacokinetics (PK) of sepantronium between US and Japanese patient populations using data obtained from two phase 1 studies being conducted in a similar design, one conducted in the USA and the other in Japan. Patients with a confirmed advanced solid tumor or non‐Hodgkin lymphoma (NHL) (US only) that were refractory to standard therapy or for which no standard therapy was available participated in these studies. Sepantronium bromide was administered as a continuous intravenous infusion for 168 h (7 days) every 21 days. During the first two treatment cycles, serial blood and urine samples were collected for up to 48 h after termination of sepantronium bromide infusion. Forty‐one subjects in the US study (including five patients with NHL) and 33 patients in the Japanese study were enrolled in both studies and 35 in US and 32 in Japan had adequate samples for PK evaluation. The PK parameters were calculated by non‐compartment analysis method and were compared in the US and Japanese populations. The geometric mean ratios (90% confidence intervals) of area under the concentration–time curve, steady state concentration and amount excreted into urine between Japanese and US populations were 1.068 (0.932–1.224), 1.141 (0.996–1.307) and 0.981 (0.855–1.125), respectively. There appear to be no PK differences between the US and Japanese patients with solid tumors or NHL. Copyright © 2012 John Wiley & Sons, Ltd.
Size discrimination in rat and mouse gastric emptying
Authors: Jang Shih‐Fan , Goins Beth A. , Phillips William T. , Santoyo Cristina , Rice‐Ficht Allison , McConville Jason T.
Published: November 2012

Objectives

To investigate the relationship between particle size and gastric emptying in rodents using radiolabeled insoluble polymethyl methacrylate (PMMA) microcapsules/beads.

Methods

PMMA microcapsules (50–500 µm) and beads (0.5–3 mm) loaded with technetium‐99 m diethylenetriamine pentaacetic acid (99mTc‐DTPA) were administered to ICR mice or Sprague Dawley (SD) rats by oral gavage. Gamma scintiscans were acquired initially following administration and then at hourly intervals to 4 hours.

Results

Scintiscans revealed that the smallest PMMA microcapsules (50–100 µm) or beads (0.5–1 mm) were impeded in the stomach and emptied slower than large particles in both rodent species. In mice, no significant difference in gastric emptying was found with microcapsules between 100 and 300 µm in diameter (p = 0.25) and particles more than 300 µm could not be administered. In rats, capsules containing 0.5–3 mm beads were stuck to the esophagus (up to 1 hour), this was a limitation of dosing beads of this size because they cannot be suspended in a liquid media for oral gavage purposes. Beads with diameters of 2–3 mm stayed in the stomach for up to 4 hours.

Conclusions

The cut‐off emptying size in ICR mice could not be determined, due to the limitation of current available dosing methods. The cut‐off emptying size in SD rats was between 1.5 and 2 mm. Therefore, particles with a diameter greater than 2 mm should not be used for gastric emptying studies of intact particles in SD rats, as their emptying is retarded in the stomach. Copyright © 2012 John Wiley & Sons, Ltd.
How is functional specificity achieved through disordered regions of proteins?
Authors: Das Rahul K. , Mittal Anuradha , Pappu Rohit V.
Published: November 2012

N‐type inactivation of potassium channels is controlled by cytosolic loops that are intrinsically disordered. Recent experiments have shown that the mechanism of N‐type inactivation through disordered regions can be stereospecific and vary depending on the channel type. Variations in mechanism occur despite shared coarse grain features such as the length and amino acid compositions of the cytosolic disordered regions. We have adapted a phenomenological model designed to explain how specificity in molecular recognition is achieved through disordered regions. We propose that the channel‐specific observations for N‐type inactivation represent distinct mechanistic choices for achieving function through conformational selection versus induced fit. It follows that the dominant mechanism for binding and specificity can be modulated through subtle changes in the amino acid sequences of disordered regions, which is interesting given that specificity in function is realized in the absence of autonomous folding.
Antigen generation and display in therapeutic antibody drug discovery – a neglected but critical player
Authors: Ebersbach Hilmar , Geisse Sabine
Published: November 2012

Disease intervention by targeting a critical pathway molecule through a blocking antibody or interference by therapeutic proteins is currently en vogue. Generation of blocking antibodies or therapeutic proteins inevitably requires the production of recombinant proteins or cell‐based immunogens. Thus, one could call the antigen molecule the neglected player in antibody drug discovery. The variety of methods available for making recombinant proteins or recombinant cell lines that present the target on the cell surface is extensive. These need to be addressed in conjunction with biochemical and biophysical quality criteria and the experimental application intended. Fundamentally, successful production and isolation of monoclonal antibodies requires optimized antigen preparation and presentation to the immune host. This review summarizes the most important aspects of antigen generation and display, enabling logical decision making to give rise to potent high‐affinity antibodies.
Multimodal chromatography: An efficient tool in downstream processing of proteins
Authors: Kallberg Kristian , Johansson Hans‐Olof , Bulow Leif
Published: November 2012

Chromatography has become an indispensable tool for the purification of proteins. Since the regulatory demands on protein purity are expected to become stricter, the need for generating improved resins for chromatographic separations has increased. More advanced scientific investigations of protein structure/function relationships, in particular, have also been a driving force for generating more sophisticated chromatographic materials for protein separations. As a consequence, the development of alternative chromatographic strategies has been very rapid during the past decade and several new ligands have been designed and explored both in the laboratory and in large‐scale industrial settings. This review describes some of these efforts using multimodal chromatography, where two or more physicochemical properties are used to enhance the specificity of the interactions between the protein and the ligand on the chromatographic matrix. In addition to experimental studies, computer modeling of ligand‐protein binding has improved the design of ligands for protein recognition. The use of descriptors as well as in silico docking methods have been implemented to design multimodal resins in several instances.
Electrospun synthetic and natural nanofibers for regenerative medicine and stem cells
Authors: Kai Dan , Jin Guorui , Prabhakaran Molamma P. , Ramakrishna Seeram
Published: November 2012

Nanofibers are attractive substrates for tissue regeneration applications because they structurally mimic the native extracellular matrix. Electrospinning has been recognized as one of the most efficient techniques to fabricate polymer nanofibers. Recent research has demonstrated that cellular responses, for example attachment, proliferation and differentiation, can be modulated by tuning nanofiber properties. In combination with other processing techniques, such as particulate leaching or three‐dimensional printing, nanofibrous scaffolds incorporating macroporous networks could be developed to enhance infiltration of cells. Three dimensional nanofiber‐based constructs offer an opportunity to achieve advanced functional tissue regeneration. This review explores the advantageous effects of nanofibers on cell behaviors compared to traditional scaffolds.
In vitro and in vivo evaluation of L‐lactide/ε‐caprolactone copolymer scaffold to support myoblast growth and differentiation
Authors: Bandyopadhyay Balaji , Shah Viru , Soram Memtombi , Viswanathan Chandra , Ghosh Deepa
Published: November 2012

Skeletal muscle regeneration involves the activation of satellite cells to myoblasts, followed by their proliferation and fusion to form multinucleated myotubes and myofibers. The potential of in vitro proliferated myoblasts to treat various diseases and tissue defects can be exploited using tissue‐engineering principles. With an aim to develop a biocompatible and biodegradable scaffold that supports myoblast growth and differentiation, we have developed a porous sponge with 70/30 L‐lactide/ε‐caprolactone copolymer (PLC) using a phase inversion combined with particulate leaching method. Degradation studies indicated that the sponge retained its structural integrity for 5 months in vitro and had undergone complete biodegradation within 9 months in vivo. The sponge supported human myoblasts attachment and its proliferation. Myoblasts seeded on the PLC sponge differentiated and fused in vitro to form myotubes expressing myosin heavy chain. Histological and molecular analyses of the PLC scaffolds seeded with green fluorescent protein‐labeled human myoblasts and implanted ectopically under the skin in SCID mice demonstrated the presence of multinucleated myotubes expressing human muscle‐specific markers. Our results suggest that PLC sponges loaded with myoblasts can be used for skeletal muscle engineering or for inducing muscle repair. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2013
General Belongingness, Workplace Belongingness, and Depressive Symptoms
Authors: Cockshaw Wendell David , Shochet Ian M. , Obst Patricia L.
Published: November 2012

Research has shown that a strong relationship exists between belongingness and depressive symptoms; however, the contribution of specific types of belongingness remains unknown. Participants (N=369) completed the sense of belonging instrument, psychological sense of organizational membership, and the depression scale of the depression anxiety stress scales. Factor analysis demonstrated that workplace and general belongingness are distinct constructs. When regressed onto depressive symptoms, these belongingness types made independent contributions, together accounting for 45% of variance, with no moderation effects evident. Hence, general belongingness and specific workplace belongingness appear to have strong additive links to depressive symptoms. These results add support to the belongingness hypothesis and sociometer theory and have significant implication for depression prevention and treatment. Copyright © 2012 John Wiley & Sons, Ltd.
Targeting a Regulatory Element in Human Thymidylate Synthase mRNA
Authors: Brunn Nicholas D. , Garcia Sega Emily , Kao Melody B. , Hermann Thomas
Published: November 2012

Thymidylate synthase (TS) is a key enzyme in the biosynthesis of thymidine. The use of TS inhibitors in cancer chemotherapy suffers from resistance development in tumors through upregulation of TS expression. Autoregulatory translation control has been implicated with TS overexpression. TS binding at its own mRNA, which leads to sequestration of the start codon, is abolished when the enzyme forms an inhibitor complex, thereby relieving translation suppression. We have used the protein‐binding site from the TS mRNA in the context of a bicistronic expression system to validate targeting the regulatory motif with stabilizing ligands that prevent ribosomal initiation. Stabilization of the RNA by mutations, which were studied as surrogates of ligand binding, suppresses translation of the TS protein. Compounds that stabilize the TS‐binding RNA motif and thereby inhibit ribosomal initiation might be used in combination with existing TS enzyme‐targeting drugs to overcome resistance development during chemotherapy.
NanoSelect Pd Catalysts: What Causes the High Selectivity of These Supported Colloidal Catalysts in Alkyne Semi‐Hydrogenation?
Authors: Witte Peter T. , Boland Susan , Kirby Fiona , van Maanen Ramon , Bleeker Bas F. , de Winter D. A. Matthijs , Post Jan A. , Geus John W. , Berben Peter H.
Published: November 2012

In recent years, many articles describing the preparation of supported colloidal catalysts have been published. The semi‐hydrogenation of alkynes to yield cis‐alkenes is often used as a test reaction in these publications. Many highly selective catalysts are described. However, a satisfactory explanation for the high reported selectivity has never been shown. Here we report a study on the possible effects that lead to the large selectivity differences between current commercial Pd/C catalysts and our newly developed NanoSelect catalysts. The focus is on differences in chemical composition as well as catalyst characteristics. We use a focused ion beam scanning electron microscope (FIB‐SEM) to locate the metal particle with respect to the surface of the support. FIB‐SEM analysis clearly shows the absence of the active component inside the support material, which could explain the high observed selectivity. Nevertheless, an effect of the stabilizer cannot be ruled out.
Catalytic Performance of Zeolite‐Supported Vanadia in the Aerobic Oxidation of 5‐hydroxymethylfurfural to 2,5‐diformylfuran
Authors: Sádaba Irantzu , Gorbanev Yury Y. , Kegnæs Søren , Putluru Siva Sankar Reddy , Berg Rolf W. , Riisager Anders
Published: November 2012

The catalytic performance of zeolite‐supported vanadia catalysts was examined for the aerobic oxidation of 5‐hydroxymethylfurfural (HMF) to 2,5‐diformylfuran (DFF) in organic solvents such as N,N‐dimethylformamide (DMF), methyl isobutyl ketone, toluene, trifluorotoluene and DMSO. Catalysts based on the four different zeolite supports H‐beta, H‐Y, H‐mordenite, and H‐ZSM‐5 with 1–10 wt % vanadia loading were prepared and characterized by nitrogen physisorption, X‐ray powder diffraction, scanning electron microscopy, ammonia temperature‐programmed desorption, Raman spectroscopy and UV/Vis spectrophotometry. The H‐beta zeolite catalysts were found to contain highly dispersed vanadium oxide species at all loadings, and provided the highest reaction selectivity towards DFF and the lowest metal leaching of the examined systems. In particular, 1 wt % V2O5/H‐beta was found to be a stable, recyclable, and non‐leaching catalyst for the production of DFF under mild conditions in DMF as solvent, although with low DFF yield. To increase the yield, oxidation of HMF at elevated pressures was also investigated with this catalyst. Under optimized conditions, a reaction selectivity towards DFF of >99 % at 84 % HMF conversion was obtained, albeit with some contribution from lixiviated species to the total catalyst activity.
Isolation and Structural Elucidation of Armeniaspirols A–C: Potent Antibiotics against Gram‐Positive Pathogens
Authors: Dufour Cosima , Wink Joachim , Kurz Michael , Kogler Herbert , Olivan Helene , Sablé Serge , Heyse Winfried , Gerlitz Martin , Toti Luigi , Nußer Antje , Rey Astrid , Couturier Cedric , Bauer Armin , Brönstrup Mark
Published: November 2012

In an antibiotic lead discovery program, the known strain Streptomyces armeniacus DSM19369 has been found to produce three new natural products when cultivated on a malt‐containing medium. The challenging structural elucidation of the isolated compounds was achieved by using three independent methods, that is, chemical degradation followed by NMR spectroscopy, a computer‐assisted structure prediction algorithm, and X‐ray crystallography. The compounds, named armeniaspirol A–C (2–4), exhibit a compact, hitherto unprecedented chlorinated spiro[4.4]non‐8‐ene scaffold. Labeling experiments with [1‐13C] acetate, [1,2‐13C2] acetate, and [U‐13C] proline suggest a biosynthesis through a rare two‐chain mechanism. Armeniaspirols displayed moderate to high in vitro activities against Gram‐positive pathogens such as methicillin‐resistant S. aureus (MRSA) or vancomycin resistant E. faecium (VRE). As analogue 2 was active in vivo in an MRSA sepsis model, and showed no development of resistance in a serial passaging experiment, it represents a new antibiotic lead structure.
tert‐Butyldimethylsilyl‐Directed Highly Enantioselective Approach to Axially Chiral α‐Allenols
Authors: Ye Juntao , Fan Wu , Ma Shengming
Published: November 2012

A highly efficient and enantioselective synthesis of axially chiral α‐allenols was realized in practical yields with 96–99 % ee or de from TBS‐protected propargylic alcohols, aldehydes, and a commercially available, inexpensive, chiral, secondary amine (S)‐α,α‐diphenylprolinol or its enantiomer followed by desilylation. The easily removable TBS group not only acts as a protecting group, but also as a possible sterically directing group for the excellent enantioselectivity and in situ prevention of possible allene racemization.
Experimental and Theoretical Studies on the Bismuth‐Triflate‐Catalysed Cycloisomerisation of 1,6,10‐Trienes and Aryl Polyenes
Authors: Godeau Julien , Fontaine‐Vive Fabien , Antoniotti Sylvain , Duñach Elisabet
Published: November 2012

Cycloisomerisation of polyenes such as diethyl geranylprenylmalonate [(E)‐1 a], diethyl geranylphenylmalonate [(E)‐2 a] and diethyl cinnamylgeranylmalonate [(E,E)‐3 a] catalysed by bismuth triflate was studied from experimental and theoretical viewpoints. Several intermediates were isolated and characterised, and calculated transition‐state structures are proposed for the three reactions. The diastereoselectivity observed during the reaction of (E)‐ or (Z)‐2 a in favour of the formation of trans‐fused bicyclic products is discussed in detail. The nature of the active catalytic species derived from bismuth triflate was also investigated, and the formation of a hybrid Lewis acid/Brønsted acid catalyst with water molecules is proposed, supported by experimental and theoretical data.
Synthesis and Structure–Property Relationships of 2,2′‐Bis(benzo[b]phosphole) and 2,2′‐Benzo[b]phosphole–Benzo[b]heterole Hybrid π Systems
Authors: Hayashi Yukiko , Matano Yoshihiro , Suda Kayo , Kimura Yoshifumi , Nakao Yoshihide , Imahori Hiroshi
Published: November 2012

The first comprehensive study of the synthesis and structure–property relationships of 2,2′‐bis(benzo[b]phosphole)s and 2,2′‐benzo[b]phosphole–benzo[b]heterole hybrid π systems is reported. 2‐Bromobenzo[b]phosphole P‐oxide underwent copper‐assisted homocoupling (Ullmann coupling) and palladium‐catalyzed cross‐coupling (Stille coupling) to give new classes of benzo[b]phosphole derivatives. The benzo[b]phosphole–benzo[b]thiophene and ‐indole derivatives were further converted to P,X‐bridged terphenylenes (X=S, N) by a palladium‐catalyzed oxidative cycloaddition reaction with 4‐octyne through the CβH activation. X‐ray analyses of three compounds showed that the benzo[b]phosphole‐benzo[b]heterole derivatives have coplanar π planes as a result of the effective conjugation through inter‐ring CC bonds. The π–π* transition energies and redox potentials of the cis and trans isomers of bis(benzo[b]phosphole) P‐oxide are very close to each other, suggesting that their optical and electrochemical properties are little affected by the relative stereochemistry at the two phosphorus atoms. The optical properties of the benzo[b]phosphole–benzo[b]heterole hybrids are highly dependent on the benzo[b]heterole subunits. Steady‐state UV/Vis absorption/fluorescence spectroscopy, fluorescence lifetime measurements, and theoretical calculations of the non‐fused and acetylene‐fused benzo[b]phosphole–benzo[b]heterole π systems revealed that their emissive excited states consist of two different conformers in rapid equilibrium.
Bloom of Hemidiscus hardmannianus (Bacillariophyceae) and Its Impact on Water Quality and Plankton Community Structure in a Mangrove Wetland
Authors: Naha Biswas Sejuti , Godhantaraman Nallamuthu , Sarangi Ranjit K. , Bhattacharya Bhaskar D. , Sarkar Santosh K. , Satpathy Kamala K.
Published: November 2012

An intense monospecies bloom of the centric diatom Hemidiscus hardmannianus (Greville) Mann. (Bacillariophyceae) occurred in the coastal waters of Sundarban mangrove wetland, India on 22 July, 2010. The species was abruptly flourished (mean density 8.86 × 106 cells/L) resulting intense green coloration of water. The greatest impoverishment of diversity and density of phytoplankton, micro‐ and mesozooplankton community was observed during the bloom. The phytoplankton community showed an extreme reduction in diversity (12 species to one) and sharp decrease in standing stock (12.84 × 103 to 8.86 × 106 cells/L) during this period. The late bloom condition coincided with sudden and huge arrival of a clupoid fish Hilsa ilisha which forms the most potential fisheries in Sundarban deltaic region. An attempt has been made to correlate the satellite remote sensing‐derived information to the bloom conditions. The MODIS‐Aqua derived chlorophyll and TMI satellite derived sea surface temperature and wind speed maps have been interpreted.
Helium Nanodroplet Isolation Spectroscopy and ab Initio Calculations of HO3(O2)n Clusters
Authors: Liang Tao , Raston Paul L. , Douberly Gary E.
Published: November 2012

HO3(O2)n clusters are formed by the sequential addition of the hydroxyl radical and O2 molecules to superfluid helium nanodroplets. IR laser spectroscopy in the fundamental OH stretching region reveals the presence of several bands assigned to species as large as n=4. Detailed ab initio calculations are carried out for multiple isomers of cis‐ and trans‐HO3O2, corresponding to either hydrogen‐ or oxygen‐bonded van der Waals complexes. Comparisons to theory suggest that the structure of the HO3O2 complex formed in helium droplets is a hydrogen‐bonded 4A′ species consisting of a trans‐HO3 core. The computed binding energy of the complex is approximately 240 cm−1. Despite the weak interaction between trans‐HO3 and O2, nonadditive redshifts of the OH stretching frequency are observed upon successive solvation by O2 to form larger clusters with n>1.
Oxide Coating of Alumina Nanoporous Structure Using ALD to Produce Highly Porous Spinel
Authors: Rauwel Erwan , Nilsen Ola , Rauwel Protima , Walmsley John Charles , Frogner Heidi Berge , Rytter Erling , Fjellvåg Helmer
Published: November 2012

In this work we show that atomic layer deposition (ALD) stands out as a very promising method for coating nanomaterials and, more specifically, nanoporous materials of technological interest in heterogeneous catalysis. ALD is capable of coating extremely complex shapes with high conformality and high aspect ratios. The current work describes deposition of ZnO and CoO thin films on γ‐alumina nanoporous particles with sizes ranging from 20 to 100 µm in diameter, as well on aluminum membrane discs (anodiscs), and converting the surfaces into nanoporous, mechanically more robust spinel phases. We maintain the porosity of the supporting γ‐alumina particle, despite the addition of material to the 16 nm pores, by utilizing subsequent reactions between the coated layer and γ‐alumina, following the Kirkendall mechanism. The oxide thin film coatings are deposited at 175 and 167°C for ZnO and cobalt oxide, respectively, and thereafter annealed at from 600 to 1000°C for 3 h. This represents a new way to produce highly porous spinel particles and spinel‐coated membrane discs.
QoS aware transmission control scheme for multihop WiMAX network
Authors: Ismael Fath Elrahman , Syed Yusof Sharifah K. , Abbas Mazlan , Abdul Latiff N.M. , Fisal Norsheila
Published: November 2012

The IEEE 802.16j Mobile Multihop Relay (MMR) WiMAX network allows the number of hops between the end user and the base station to be more than two hops. It supports non‐real‐time Polling Service, which considers the minimum reserved rate and the maximum sustained rate as a QoS requirements. The reliability of sending the data over MMR WiMAX is achieved by using Transmission Control Protocol (TCP) in transport layer and automatic repeat request in the link layer. However, the use of automatic repeat request in the link layer makes the round trip time fluctuate rapidly, which increases the possibility of retransmission timeout (RTO) expiration. TCP performance degrades because of frequent timeout, and hence the QoS transmission rates cannot be satisfied. Therefore, this paper presents an RTO smoothing scheme and QoS aware transmission control to enhance the performance of data transmission over MMR WiMAX networks. The RTO smoothing scheme aims to reduce the frequent timeout occurrences. The slow start threshold and maximum congestion window are adjusted to satisfy the required QoS and it provides transmission rate fairness for the users at different hops. The results showed that, the proposed schemes reduce the timeout, and improve the utilization of the allocated resources and TCP throughput. Copyright © 2012 John Wiley & Sons, Ltd.
Prenatal maternal stress affects motor function in 5½‐year‐old children: Project Ice Storm
Authors: Cao Xiujing , Laplante David P. , Brunet Alain , Ciampi Antonio , King Suzanne
Published: November 2012

Evidence suggests that prenatal maternal stress (PNMS) has long‐term effects on several outcomes, yet effects on neuromotor function are relatively unknown. We aimed to determine whether disaster‐related PNMS predicts motor functioning in young children and whether timing of exposure and sex of the child moderate these effects. Objective and subjective PNMS levels were assessed among pregnant women exposed to a natural disaster. Their children's bilateral coordination, balance, and visual motor integration (VMI) were assessed at 5½ years. Girls performed better than boys. Objective stress exposure and subjective distress interacted such that when subjective distress was high, no added effect of objective hardship was observed; when subjective distress was low, objective hardship showed a negative effect. In girls, late pregnancy exposure was associated with poorer outcomes. In conclusion, disaster‐related PNMS is associated with relatively lower motor functions in exposed offspring. Exposure timing, sex, and type of stress influenced the effects. © 2012 Wiley Periodicals, Inc. Dev Psychobiol 56: 117–125, 2014.
Gene flow at major transitional areas in sea bass (Dicentrarchus labrax) and the possible emergence of a hybrid swarm
Authors: Quéré Nolwenn , Desmarais Erick , Tsigenopoulos Costas S. , Belkhir Khalid , Bonhomme François , Guinand Bruno
Published: November 2012

The population genetic structure of sea bass (Dicentrarchus labrax) along a transect from theAtlanticOcean (AO) to theEasternMediterranean (EM) Sea differs from that of most other marine taxa in this area. Three populations (AO,WesternMediterranean [WM],EM) are recognized today, which were originally two allopatric populations. How two ancestral genetic units have evolved into three distinct units has not been addressed yet. Therefore, to investigate mechanisms that lead to the emergence of the centralWMpopulation, its current status, and its connectivity with the two parental populations, we applied 20 nuclear loci that were either gene associated or gene independent. Results confirmed the existence of three distinct gene pools, with higher differentiation at two transitional areas, theAlmeria‐OranFront (AOF) and of theSiculo‐TunisianStrait (STS), than within any population. Significant linkage disequilibrium and heterozygote excess indicated that theSTSis probably another tension zone, as already described for theAOF. Neutrality tests fail to reveal marker loci that could be driven by selection within or among metapopulations, except for locusDLA0068. Collectively, results support that the central WM population arose by trapping two tensions zones at distinct geographic locations of limited connectivity. Population assignment further revealed that WM individuals were more introgressed than individuals from the other two metapopulations. This suggests that this population might result from hybrid swarming, and was or is still seeded by genes received through the filter of each tension zone.
Permeability of the landscape matrix between amphibian breeding sites
Authors: Van Buskirk Josh
Published: November 2012

For organisms that reproduce in discrete habitat patches, land cover between patches (known as the matrix) is important for dispersal among breeding sites. Models of patchy populations often incorporate information on the permeability of the matrix to dispersal, sometimes based on expert opinion. I estimated the relative resistance to gene flow of land cover types and barriers usingFSTcalculated from microsatellite markers in two amphibians, within an 800‐km2area in northernSwitzerland. The species included a frog (Rana temporaria: 996 individuals, 48 populations, seven markers) and a newt (Triturus alpestris: 816 individuals, 41 populations, seven markers). Open fields and urban areas were more resistant to gene flow than forested land; roads and highways also reduced permeability. Results were similar for the two species. However, differences in resistance among matrix elements were relatively low: gene flow through urban areas was reduced by only 24–42% relative to forest; a divided highway reduced gene flow by 11–40% and was 7–8 times more resistant than a secondary road. These data offer an empirically based alternative to expert opinion for setting relative resistance values in landscape models.
Two‐Step Spin Transition in an Iron(II) Coordination Network Based on Flexible Bitopic Ligand 1‐(Tetrazol‐1‐yl)‐3‐(1,2,3‐triazol‐1‐yl)propane
Authors: Białońska Agata , Bronisz Robert , Kusz Joachim , Zubko Maciej
Published: November 2012

Flexible bitopic ligand 1‐(tetrazol‐1‐yl)‐3‐(1,2,3‐triazol‐1‐yl)propane (ptrtz) reacts with Fe(ClO4)2·6H2O to form two‐dimensional (2D) coordination network [Fe(ptrtz)3](ClO4)2·MeCN (1) in which two chemically different spin crossover (SCO) FeII centers are observed. Although two 1,2,3‐triazole and four tetrazole rings are in the first coordination sphere of the Fe1 ions, Fe2 ions are coordinated to four 1,2,3‐triazole and two tetrazole rings. Symmetry‐related FeII ions are bridged by two disordered ptrtz molecules resulting in the formation of chains that are extended in the same direction. Alternately arranged chains containing Fe1 or Fe2 ions are cross‐linked by single ptrtz molecules to form 2D layers. At room temperature, the complex remains in a high‐spin (HS) form (χMT = 3.46 cm3 K mol–1). Spin crossover in 1 occurs in two steps separated by an inflection point at 140 K (χMT = 2.68 cm3 K mol–1, γHS ≈ 0.76). The first step is gradual and between 220 and 140 K about a quarter of all the iron(II) ions change their spin state (T1↓ = T1↑ = 165 K). Single‐crystal X‐ray diffraction studies revealed that upon lowering the temperature from 220 to 140 K, spin crossover occurs for only half of the iron(II) ions occupying Fe2 sites. It is accompanied by an alteration of the occupancy factor of ptrtz molecules bridging the Fe2 ions. Iron(II) ions occupying Fe1 sites remain in the HS form, which inhibits compression of the polymeric layer in the Fe1···Fe1 and Fe2···Fe2 linking direction. Upon further lowering the temperature, iron(II) ions occupying Fe1 sites and the rest of the iron(II) ions occupying Fe2 sites change their spin state. The second step of the spin transition is very abrupt and is accompanied by a hysteresis loop (T2↓ = 90 K, T2↑ = 96 K). The change in the spin state by iron(II) ions occupying Fe1 and Fe2 sites involves, contrary to first step, a significant shortening of the Fe1···Fe1 and Fe2···Fe2 separations.
Synthesis, Characterization, and Selected Properties of 7‐ and 12‐Ammoniocarba‐closo‐dodecaboranes
Authors: Konieczka Szymon Z. , Himmelspach Alexander , Hailmann Michael , Finze Maik
Published: November 2012

The inner salts 12‐H3N‐closo‐1‐CB11H11 (H1) and 7‐H3N‐12‐Hal‐closo‐1‐CB11H10 [Hal = F (H3), Cl (H4)] were synthesized by a microwave‐assisted Buchwald–Hartwig amination starting from the corresponding monoiodinated {closo‐1‐CB11} clusters and LiN(SiMe3)2. H1 was methylated to result in the zwitterion 12‐Me3N‐closo‐1‐CB11H11 (2). All new compounds were characterized by multinuclear NMR spectroscopy, elemental analysis, and mass spectrometry. The crystal structures of H1·Me2CO and 2 were determined. The pKa value of H1 in aqueous solution was estimated by potentiometric titration and by 11B{1H} NMR spectroscopic studies. The stepwise deprotonation of H1 with nBuLi in [D8]THF was studied by multinuclear NMR spectroscopy. In a first step, the amine 1 is obtained and then the amide [12‐HN‐closo‐1‐CB11H11]2– and finally the trianion [12‐HN‐closo‐1‐CB11H10]3– or more probably lithiated species thereof are formed. The experimental spectroscopic and structural data, as well as the pKa value of H1 are compared to values derived from DFT and ab initio calculations.