bluuebunny/crossref_metadata_2025_split huggingface dataset:
Homobimetallic Ruthenium Vinylidene, Allenylidene, and Indenylidene Complexes: Synthesis, Characterization, and Catalytic Studies
Authors: Sauvage Xavier , Borguet Yannick , Zaragoza Guillermo , Demonceau Albert , Delaude Lionel 
Published: February 2009

Abstractmagnified imageFour homobimetallic ruthenium‐(p‐cymene) complexes bearing a tricyclohexylphosphine ligand and polyunsaturated carbon‐rich fragments were obtained via a vinylidene‐allenylidene‐indenylidene cascade pathway from the ethylene complex [(p‐cymene)Ru(μ‐Cl)3RuCl(PCy3)(η2‐C2H4)] (7a). All the products were isolated and fully characterized by IR and NMR spectroscopies. The molecular structure of the indenylidene complex 11 was determined by X‐ray crystallographic analysis. The catalytic activity of the four complexes was probed in various types of olefin metathesis reactions and compared with those of a related homobimetallic ruthenium‐benzylidene complex, as well as first, second, and third generation monometallic Grubbs catalysts. In the ring‐closing metathesis (RCM) of diethyl diallylmalonate, the homobimetallic ruthenium‐indenylidene complex 11 outperformed all the ruthenium‐benzylidene complexes under investigation and was only slightly less efficient than its monometallic parent. Cross‐metathesis experiments with ethylene showed that deactivation of ruthenium‐benzylidene or indenylidene complexes was due to the rapid bimolecular decomposition of methylidene active species into ethylene complex 7a. Vinylidene and allenylidene complexes were far less efficient catalyst precursors for ring‐opening metathesis polymerization (ROMP) or RCM and remained inert under an ethylene atmosphere. Their catalytic activity was, however, substantially enhanced upon addition of an acidic co‐catalyst that most likely promoted their in situ transformation into indenylidene species. Due to its straightforward synthesis and high metathetical activity, homobimetallic ruthenium‐indenylidene complex 11 is a valuable intermediate for the preparation of the Hoveyda–Grubbs catalyst [Cl2Ru(PCy3)(CH‐o‐O‐i‐PrC6H4)] via stoichiometric cross‐metathesis with 2‐isopropoxystyrene. The procedure did not require any sacrificial phosphine and the transition metal not incorporated into the final product was easily recovered and recycled at the end of the process.
The role of the brain‐derived neurotrophic factor (BDNF) val66met variant in the phenotypic expression of obsessive‐compulsive disorder (OCD)
Authors: Katerberg Hilga , Lochner Christine , Cath Danielle C. , de Jonge Peter , Bochdanovits Zoltán , Moolman‐Smook Johanna C. , Hemmings Sîan M.J. , Carey Paul D. , Stein Dan J. , Sondervan David , Boer Johan A. den , van Balkom Anton J.L.M. , Polman Annemiek , Heutink Peter 
Published: February 2009

AbstractEvidence suggests that the Val66Met variant of the brain‐derived neurotrophic factor (BDNF) gene may play a role in the etiology of Obsessive‐Compulsive Disorder (OCD). In this study, the role of the BDNF Val66Met variant in the etiology and the phenotypic expression of OCD is investigated. Associations between the BDNF Val66Met variant and OCD, obsessive‐compulsive symptom dimensions, Yale‐Brown Obsessive Compulsive Scale (YBOCS) severity scores, age of onset and family history of obsessive‐compulsive symptoms were assessed. The BDNF Val66Met variant was genotyped in 419 patients with sub‐/clinical OCD and 650 controls. No differences in allele or genotype frequency were observed between cases and controls. In females with OCD, the Met66Met genotype was associated with later age of onset and a trend for a negative family history, whereas the Val66Val genotype was associated with a trend for lower YBOCS severity scores. Item‐level factor analysis revealed six factors: 1) Contamination/cleaning; 2) Aggressive obsessions/checking; 3) Symmetry obsessions, counting, ordering and repeating; 4) Sexual/religious obsessions; 5) Hoarding and 6) Somatic obsessions/checking. A trend was found for a positive association between Factor 4 (Sexual/religious obsessions) and the BDNF Val66Val genotype. The results suggest that BDNF function may be implicated in the mediation of OCD. We found that for the BDNF Met66Met genotype may be associated with a milder phenotype in females and a possible role for the BDNF Val66Val genotype and the BDNF Val66 allele in the sexual/religious obsessions. © 2009 Wiley‐Liss, Inc.
Autoantibodies against β‐amyloid are common in Alzheimer's disease and help control plaque burden
Authors: Kellner Alexander , Matschke Jakob , Bernreuther Christian , Moch Holger , Ferrer Isidro , Glatzel Markus 
Published: February 2009

AbstractObjectiveActive or passive immunization of Alzheimer's disease (AD) patients leads to targeting of β‐amyloid plaques by immunoglobulins (IgG) and their subsequent removal by microglia. Here, we investigate whether naturally occurring autoantibodies to β‐amyloid contribute to β‐amyloid plaque removal in nonimmunized AD patients.MethodsWe generated an AD tissue microarray with 2,325 tissue specimens from 3 defined central nervous system regions of 48 AD patients and 48 age‐matched control patients. Absolute quantification of β‐amyloid, β‐amyloid plaque‐bound IgG, and phagocytic, resting, and activated microglia and microhemorrhages was done using a standardized, highly reproducible scoring system.ResultsThe majority of neuritic plaques are decorated by IgG. AD patients with prominently IgG‐labeled neuritic plaques have a significantly reduced plaque burden and an increase in phagocytic microglia, yet no increase in microhemorrhages.InterpretationAutoantibodies directed against β‐amyloid are common in AD patients and may contribute in controlling plaque burden. Ann Neurol 2009;65:24–31
Genetic determinants of hair color and parkinson's disease risk
Authors: Gao Xiang , Simon Kelly C. , Han Jiali , Schwarzschild Michael A. , Ascherio Alberto 
Published: February 2009

AbstractObjectiveA history of melanoma is associated with increased risks for Parkinson's disease (PD). We examined whether hair color, one of the most important phenotypes of pigmentation and a risk factor for melanoma, was associated with PD risk in the Health Professionals Follow‐up Study (HPFS; 1986–2002) and the Nurses' Health Study (NHS; 1980–2002).MethodsWe included 38,641 men and 93,661 women who were free of PD at baseline. Information on natural hair color in early adulthood (age 18–21 years) was assessed via a questionnaire. We also conducted a case–control study (298 PD cases) nested in these two cohorts to examine the association between the melanocortin1‐receptor Arg151Cys polymorphism and PD risk. Relative risks (RRs) were estimated using Cox proportional hazards models in the cohort analyses and conditional logistic regression in the nested case–control study.ResultsPD risk increased with decreasing darkness of hair color. Pooled RRs for PD were 1 (reference), 1.40, 1.61, and 1.93 (95% confidence interval, 1.1–3.4) for black, brown, blond, and red hair, respectively, after adjusting for age, smoking, ethnicity, and other covariates. The associations between hair color and PD were particularly strong for relative younger onset of PD (<70 yr) (adjusted RR for red vs black hair = 3.83; 95% confidence interval, 1.7–8.7). In the case–control study, participants with Cys/Cys genotype, which was associated with red hair, had a greater PD risk, relative to the Arg/Arg genotype (adjusted RR, 3.15; 95% confidence interval, 1.1–9.4).InterpretationThese findings suggest a potential role of pigmentation in PD. Ann Neurol 2009;65:76–82
Pelizaeus–Merzbacher–Like disease presentation of MCT8 mutated male subjects
Authors: Vaurs‐Barrière Catherine , Deville Marlène , Sarret Catherine , Giraud Geneviève , Des Portes Vincent , Prats‐Viñas José‐Maria , De Michele Giuseppe , Dan Bernard , Brady Angela F. , Boespflug‐Tanguy Odile , Touraine Renaud 
Published: February 2009

AbstractPelizaeus–Merzbacher Disease is an X‐linked hypomyelinatiing leukodystrophy. We report mutations in the thyroid hormone transporter gene MCT8 in 11% of 53 families affected by hypomyelinating leukodystrophies of unknown aetiology. The 12 MCT8 mutated patients express initially a Pelizaeus–Merzbacher‐Like disease phenotype with a latter unusual improvement of magnetic resonance imaging white matter signal despite absence of clinical progression. This observation underlines the interest of determining both free T3 and free T4 serum concentrations to screen for MCT8 mutations in young patients (<3 y) with a severe Pelizaeus–Merzbacher‐Like disease presentation or older severe mentally retarded male patients with “hypomyelinated” regions. Ann Neurol 2009;65:114–118
“Covalent Capture”: Verschmelzung von kovalenter und nichtkovalenter Synthese
Authors: Prins Leonard J. , Scrimin Paolo 
Published: February 2009

AbstractEs genügt, die passenden Moleküle zusammenzubringen, um die irreversible oder reversible Bildung einer kovalenten Bindung einzuleiten. Die Covalent‐Capture‐Strategie, bei der eine supramolekulare Wechselwirkung der kovalenten Bindungsbildung vorausgeht (siehe Schema), tritt bei unterschiedlichsten biologischen und synthetischen Systemen in Erscheinung und kann für zahlreiche Anwendungen genutzt werden.magnified imageDieser Aufsatz befasst sich mit Molekülen auf der Suche nach einem geeigneten Partner, mit dem sie eine Verbindung eingehen können. Ob das erste Treffen in einer festen Bindung endet, hängt von vielen Faktoren ab, z. B. von der Vereinbarkeit von Größe, Form und Reaktivität, von der geeigneten Anordnung der reaktiven Gruppen und von den Einflüssen des Mediums. In gewisser Weise spielt der Chemiker die Rolle des Zeremonienmeisters, der mit einer erfolgreichen Verbindung belohnt wird. Giottos Gemälde “Die Vermählung Mariä” soll die hierbei beteiligten Prinzipien der supramolekularen Chemie versinnbildlichen.
Ein substituentenfreier Galliumligand durch Hydrogenolyse von koordiniertem GaCp*: Synthese und Struktur des hoch fluktionalen [Ru2(Ga)(GaCp*)7(H)3]
Authors: Cadenbach Thomas , Gemel Christian , Schmid Rochus , Halbherr Markus , Yusenko Kirill , Cokoja Mirza , Fischer Roland A. 
Published: February 2009

AbstractDer vollständige Ligandenaustausch durch Hydrogenolyse von [Ru(η4‐cod)(η6‐cot)] in Gegenwart von GaCp* führt unter milden Bedingungen zu der Titelverbindung, in der ein „nacktes“ Galliumatom zwei Rutheniumzentren verbrückt (siehe Bild: C weiß, Ga blau, Ru rot). Dieser Cluster kann als abgefangenes Intermediat auf dem Weg zu gemischtmetallischen Nanopartikeln angesehen werden. cot=1,3,5‐Cyclooctatrien; cod=1,5‐Cyclooctadien; Cp*=C5Me5.magnified image
Biomimetic Total Synthesis of (±)‐Pallavicinolide A
Authors: Dong Jia‐Qiang , Wong Henry N. C. 
Published: February 2009

AbstractVom Teil zum Ganzen: Die erste Totalsynthese des natürlich vorkommenden Diterpens Pallavicinolid A ist gelungen. Besonders hervorzuheben sind drei biomimetische Umwandlungen: eine basenunterstützte Grob‐Fragmentierung, eine Singulettsauerstoff‐Oxidation und eine intramolekulare Diels‐Alder‐Cycloaddition.magnified image
Biomimetic Total Synthesis of (±)‐Pallavicinolide A
Authors: Dong Jia‐Qiang , Wong Henry N. C. 
Published: February 2009

AbstractPiecing it together: The first total synthesis of naturally occurring diterpene pallavicinolide A was achieved. Notable features are highlighted by three key biomimetic transformations: a base‐promoted Grob fragmentation, a singlet oxygen oxidation, and an intramolecular Diels–Alder cycloaddition.magnified image
Preparation and characterization of chloroacetylated polystyrene‐supported zinc complexes and evaluation of their catalytic activities for the synthesis of 1,1‐diacetates
Authors: Wang Liang , Cai Chun 
Published: February 2009

AbstractZinc chloride was immobilized onto chloroacetylated polystyrene via different linkages to afford polymer‐supported Lewis acid catalysts. The functionalized beads and the immobilized catalysts were characterized by elemental analysis, Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, and inductively coupled plasma and thermal analysis. The reaction of aldehydes with anhydride in the presence of the supported catalysts was investigated. The effects of various parameters, including the solvent, amount of catalyst, and temperature, on the reaction were also studied. We found that the reaction proceeded smoothly under solvent‐free conditions at room temperature and afforded the corresponding acylals in good yields. Moreover, the catalysts could be recovered easily and reused several times without a significant loss in activity. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis, swelling behaviors, and slow‐release characteristics of a guar gum‐g‐poly(sodium acrylate)/sodium humate superabsorbent
Authors: Wang Wenbo , Wang Aiqin 
Published: February 2009

AbstractSuperabsorbents used in agricultural and ecological projects with low‐cost, slow‐release fertilizers and environmentally friendly characteristics have been extensively studied. The use of a natural polymer as the matrix and then further polymerization with some functional material has become the preferred method. In this work, with natural guar gum (GG), partially neutralized acrylic acid, and sodium humate (SH) as the raw materials, ammonium persulfate as the initiator, and N,N′‐methylenebisacrylamide (MBA) as the crosslinker, GG‐g‐poly(sodium acrylate) (PNaA)/SH superabsorbents were synthesized through a solution polymerization reaction and were characterized with Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis. The effects of the SH content and MBA concentration on the water absorbency were investigated. The results showed that the introduction of SH into the GG‐g‐PNaA system could improve the water absorbency, swelling rate, pH‐resistant property, and reswelling capability, and the superabsorbent containing 15 wt % SH had the highest water absorbency of 532 g/g of sample in distilled water and 62 g/g of sample in a 0.9 wt % NaCl solution. The slow release in water and water retention in sandy soil tests revealed that the superabsorbent could act as a fertilizer as well as an effective water‐saving material for agricultural applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Quantitative effects of synthesis conditions on oil absorptive properties of oil gels based on EPDM/4‐tert‐Butylstyrene
Authors: Wu Bo , Zhou Mei H. 
Published: February 2009

AbstractThe oil absorption properties of porous polymeric gels are dependent on their synthesis conditions. In this work, we have investigated whether it is feasible to find a quantitative relationship between the synthesis conditions of porous poly(EDPM/4‐tert‐Butylstyrene) gels and their behavior in the kerosene absorption through a factorial design of experiments. For this purpose, a series of such oil gels have been synthesized in toluene with various divinylbenzene (DVB) and EPDM contents. The kerosene absorbency and kerosene‐absorption kinetics of oil gels were determined. Finally, empirical models correlating the synthesis conditions with the kerosene absorbency (Qeq) and kerosene‐absorption kinetic constant (K) were calculated; it was observed that lower the DVB concentration and higher the EPDM fraction in the monomeric mixtures, the higher the kerosene absorbency. With regard to the kerosene‐absorption kinetics, the largest K value was achieved with the lowest DVB concentration and the highest EPDM fraction. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Improved processing behaviors and mechanical properties of polyolefin elastomer blends prepared by ultrasound‐assisted extrusion
Authors: Jiang Genjie , Wu Hong , Xie Tingting , Guo Shaoyun 
Published: February 2009

AbstractTo improve the processability of ethylene‐α‐olefin copolymers (POE), POE and POE/polystyrene (PS) blends were extruded in the presence of ultrasound. On the one hand, the effect of ultrasound on the die pressure drop, extrudate productivity, melt viscosity of POE, and the processing behaviors of POE and POE/PS (80/20) blend were studied. The results showed that with increasing ultrasound power, the die pressure and melt‐apparent viscosity of POE decreased whereas the productivity of POE extrudates increased, then the processability of POE was greatly improved. On the other hand, the effects of ultrasound on the morphology, rheological, and mechanical properties of POE/PS (80/20) blend were studied. Capillary rheological results showed that the merger of ultrasound and the addition of PS showed a synergistic improvement of processability of POE. From morphological observation and rheological analysis, the compatibility of the blend was also improved in the presence of 200W ultrasound. As a result, the stress at break of compatibilized POE/PS (80/20) blend increased from 9.2 to 11.0 MPa, and the dynamic storage modulus increased at experimental temperature range, indicating that the mechanical properties of POE/PS blends can be improved by ultrasound‐assisted extrusion. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Tensile properties, barrier properties, and biodegradation in soil of compression—Molded gelatin‐dialdehyde starch films
Authors: Martucci J. F. , Ruseckaite R. A. 
Published: February 2009

AbstractGlycerol (Gly)‐plasticized gelatin (Ge) films crosslinked with dialdehyde starch (DAS) as environmentally friendly crosslinking agent were successfully produced by compression molding, demonstrating the capacity of gelatin of being transformed into films by using thermoplastic processes. The effect of DAS content on the color, light transmission, total soluble matter (TSM), water uptake (WU), water vapor permeability (WVP), oxygen permeability (OP) as well as biodegradability during soil burial was investigated. The addition of up to 10 wt % DAS (Ge‐10DAS) generated transparent films, with reduced TMS, WU, WVP, and OP values but higher extensivity than the uncrosslinked counterpart. Further incorporating DAS into plasticized‐gelatin matrix conducted to phase separation with detrimental effect of transparency and tensile properties. DAS‐containing films degraded at slow rate than the uncrosslinked counterpart, suggesting that biotic attack during soil burial is restricted by covalent crosslinking points induced by DAS. Ge‐10DAS films lost about 28% of their initial mass within the first 8 days of exposure to degrading medium; therefore, the material can be classified as rapidly degradable. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Nanosilica as dry bonding system component and as reinforcement in short nylon‐6 fiber/natural rubber composite
Authors: Mathew Leny , Narayanankutty Sunil K. 
Published: February 2009

AbstractNanoscale silica was synthesized by acid hydrolysis of sodium silicate using dilute hydrochloric acid under controlled conditions. The synthesized silica was characterized by SEM, BET adsorption, and XRD. The particle size of silica was calculated to be 13 nm from the XRD results and the surface area was found to be 295 m2/g by BET method. This synthesized nanosilica was used in place of conventional silica in HRH (hexamethylenetetramine, resorcinol and silica) bonding system for natural rubber/Nylon‐6 short fiber composite. Nanosilica was also used as reinforcing filler in natural rubber/Nylon‐6 short fiber hybrid composite. Mechanical, thermal, and dynamic mechanical properties of the composites were evaluated. The introduction of the nanosilica in hybrid composites improved the tensile strength, modulus, and tear strength through improved interaction with the matrix which is facilitated by the higher surface area. Abrasion loss and hardness were also better for the nanosilica composites. Resilience and compression set were adversely affected. The hybrid composites showed anisotropy in mechanical properties. Peak rate of thermal decomposition decreased and temperature of initiation of thermal degradation increased with silica content, indicating improved thermal stability of the hybrid composites. The storage modulus and loss modulus showed two‐stage dependence on frequency at higher fiber loading. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Thermal and morphological properties of SA/HPMC blends
Authors: Mruthyunjaya Swamy T. M. , Ramaraj B. , Siddaramaiah  
Published: February 2009

AbstractSodium alginate (SA) was blended with varying amounts of hydroxypropyl methylcellulose (HPMC) viz., 10, 20, and 30 wt % by solution casting process. Thus, the obtained blends were characterized by using different analytical techniques such as differential scanning calorimetry (DSC), thermogravimetric analyzer (TGA), Fourier transform infrared spectroscopy (FTIR), and scanning electron microcopy (SEM). FTIR studies reveal the hydrogen bond formation between hydroxyl groups of SA and HPMC polymer chains. DSC analysis shows single glass transition temperature (Tg) for SA/HPMC blends indicating compatibility and physical interaction between SA and HPMC polymer chains. TGA analysis indicates variation of thermal stability of SA with change in compositions of HPMC. SEM studies reveal uniform distribution of second phase in the blends. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
EMI shielding: Methods and materials—A review
Authors: Geetha S. , Satheesh Kumar K. K. , Rao Chepuri R. K. , Vijayan M. , Trivedi D. C. 
Published: February 2009

AbstractThe growth in the application of electronic devices across a broad spectrum of military, industrial, commercial and consumer sectors has created a new form of pollution known as noise or radio frequency interference (RFI) or electromagnetic radiation or electromagnetic interference (EMI) that can cause interference or malfunctioning of equipment. Therefore, there is a greater need for the effective shielding of components from its adverse effects. This review surveys the shielding materials like metals, conducting plastics and conducting polymers for the control of electromagnetic radiations. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Catalysis of ethylene to linear low‐density polyethylene with iron‐based diimine complex immobilized on calcosilicate and silica‐supported rac‐Et(Ind)2ZrCl2
Authors: Yan Feng‐Wen , Xu Hao , Guo Cun‐Yue , Zhang Ming‐Ge , Zhang Xiao‐Hui , Yang Hai‐Jian , Yuan Guo‐Qing 
Published: February 2009

AbstractIron‐based diimine complex was immobilized on calcosilicate (CAS‐1) to form heterogeneous precatalyst, which oligomerized ethylene to α‐olefins even without the use of aluminum alkyl compounds as activators. The α‐olefins, upon the catalysis of another catalyst, i.e., silica‐supported rac‐Et(Ind)2ZrCl2, copolymerized with ethylene to produce linear low‐density polyethylene (LLDPE). The copolymerization reactions could be performed with the addition of triethylaluminum alone because of the introduction of methylaluminoxane to CAS‐1 and silica during the supporting process. In addition to the formation of more α‐olefins with lower molar mass, the layered structure of CAS‐1 acted well in the controlled release of α‐olefins in the copolymerization process. The simultaneous employment of the aforementioned two catalysts hence resulted in high catalytic activities, smooth kinetic process, well‐regulated branching degree, higher molecular weights (Mn), improved thermal stability, and better morphology of the LLDPE obtained. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009