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  • 1
    Language: English
    In: Journal of the American Chemical Society, 15 July 2015, Vol.137(27), pp.8700-3
    Description: The asymmetric arylation of diazo compounds with aniline derivatives cooperatively catalyzed by an achiral dirhodium complex and a chiral spiro phosphoric acid is reported. The reaction provides a new method for the facile synthesis of α-diarylacetates, versatile building blocks with a diaryl tertiary chiral center, in good yields (up to 95%) with high enantioselectivities (up to 97% ee). Preliminary mechanistic studies suggest that the arylation reaction proceeds via a stepwise process, in which the enantioselectivity is controlled by a chiral spiro phosphoric acid-promoted proton shift in a zwitterionic intermediate. This work represents the first asymmetric intermolecular C(sp(2))-H bond insertion reaction with arenes.
    Keywords: Acetates -- Chemistry ; Aniline Compounds -- Chemistry ; Azo Compounds -- Chemistry ; Hydrocarbons, Aromatic -- Chemical Synthesis
    ISSN: 00027863
    E-ISSN: 1520-5126
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  • 2
    Language: English
    In: Materials Letters, Dec 1, 2012, Vol.88, p.1(4)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.matlet.2012.08.012 Byline: Lin Mao (a), Guangyin Yuan (a)(b), Shaohua Wang (a), Jialin Niu (a), Guohua Wu (a)(b), Wenjiang Ding (a)(b) Keywords: Biomaterials; Metals and alloys; Cyclic polarization; Uniform corrosion; Artificial plasma Abstract: Magnesium alloys have been currently investigated as potential biodegradable implant materials. In this study, a patent Mg alloy Mg-Nd-Zn-Zr (Jiao Da BioMg, hereafter, denoted as JDBM) was researched as a potential biodegradable stent material in comparison with the clinical trial Mg alloy WE43. The corrosion behaviors of the as-extruded JDBM and WE43 were investigated in artificial plasma by in vitro degradation measurements and cyclic polarization tests. The results showed that the corrosion rate of JDBM was much lower than that of WE43 alloy. Most importantly, the JDBM alloy showed a uniform corrosion behavior in artificial plasma, which could avoid stress concentration as well as a rapid reduction in the mechanical integrity. The investigations indicated that the as-extruded JDBM alloy may be a promising implant material suitable for stent applications. Author Affiliation: (a) National Engineering Research Center of Light Alloy Net Forming, Shanghai Jiao Tong University, Shanghai 200240, China (b) Key State Laboratory of Metal Matrix Composite, Shanghai Jiao Tong University, Shanghai 200240, China Article History: Received 22 May 2012; Accepted 6 August 2012
    Keywords: Biological Products -- Analysis ; Corrosion (Chemistry) -- Analysis ; Magnesium (Metal) -- Analysis ; Magnesium Alloys -- Analysis
    ISSN: 0167-577X
    Source: Cengage Learning, Inc.
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  • 3
    Language: English
    In: Thin Solid Films, Dec 15, 2012, Vol.525, p.35(5)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.tsf.2012.10.068 Byline: Mao-Lin Wan, Yong Jia, Fang Fang, Shuang-Sheng Zhou, Pei-Yun Wu, Dai-Yin Peng Keywords: Carbon nanotube; Electron microscopy; Commercial metal oxide; Chemical vapor deposition Abstract: Simple, low-cost and environment-friendly catalysts for synthesizing carbon nanotubes were prepared by simply calcining the mixture of commercial transition metal oxide powders and porous or crystalline MgO at 950[degrees]C. The commercial metal oxide powders, including Fe.sub.2O.sub.3, Co.sub.2O.sub.3, Ni.sub.2O.sub.3, Fe.sub.3O.sub.4 and Co.sub.3O.sub.4, were directly used without any pretreatment. Calcination of the MgO supported Fe.sub.2O.sub.3 catalysts results in the formation of MgFe.sub.2O.sub.4/MgO solid solution or the dissolution of metal into MgO lattices. High quality single- and double-walled carbon nanotubes were synthesized by thermal decomposition of methane, and were characterized by field emission scanning electron microscopy, high-resolution transmission electron microscopy, and Raman spectroscopy. The results bring forward an effective way to prepare the catalyst for synthesizing single- and double-walled carbon nanotubes. Article History: Received 25 April 2012; Revised 17 October 2012; Accepted 17 October 2012
    Keywords: Transition Metal Compounds ; Raman Spectroscopy ; Electron Microscopy ; Catalysts ; Nanotubes
    ISSN: 0040-6090
    Source: Cengage Learning, Inc.
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  • 4
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 26 June 2012, Vol.109(26), pp.10239-44
    Description: Compressional wave velocity-density (V(P)--ρ) relations of candidate Fe alloys at relevant pressure-temperature conditions of the Earth's core are critically needed to evaluate the composition, seismic signatures, and geodynamics of the planet's remotest region. Specifically, comparison between seismic V(P)--ρ profiles of the core and candidate Fe alloys provides first-order information on the amount and type of potential light elements--including H, C, O, Si, and/or S-needed to compensate the density deficit of the core. To address this issue, here we have surveyed and analyzed the literature results in conjunction with newly measured V(P)--ρ results of hexagonal closest-packed (hcp) Fe and hcp-Fe(0.85)Si(0.15) alloy using in situ high-energy resolution inelastic X-ray scattering and X-ray diffraction. The nature of the Fe-Si alloy where Si is readily soluble in Fe represents an ideal solid-solution case to better understand the light-element alloying effects. Our results show that high temperature significantly decreases the V(P) of hcp-Fe at high pressures, and the Fe-Si alloy exhibits similar high-pressure V(P)--ρ behavior to hcp-Fe via a constant density offset. These V(P)--ρ data at a given temperature can be better described by an empirical power-law function with a concave behavior at higher densities than with a linear approximation. Our new datasets, together with literature results, allow us to build new V(P)--ρ models of Fe alloys in order to determine the chemical composition of the core. Our models show that the V(P)--ρ profile of Fe with 8 wt % Si at 6,000 K matches well with the Preliminary Reference Earth Model of the inner core.
    Keywords: Density -- Research ; Density -- Analysis ; Alloys -- Research ; Alloys -- Analysis;
    ISSN: 00278424
    E-ISSN: 1091-6490
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  • 5
    Language: English
    In: Biochemical and Biophysical Research Communications, 27 May 2017, Vol.487(2), pp.362-367
    Description: The Cytosolic Protein Response (CPR) in the cytosol and the Unfolded Protein Response (UPR) and ER-associated degradation (ERAD) in the endoplasmic reticulum are major pathways of the cellular proteostasis network. However, despite years of effort, how these protein quality control systems coordinated remains largely unknown, particularly in plants. In this study, the roles of two evolutionarily conserved ERAD pathways (DOA10 and HRD1) in heat stress response were investigated through reverse genetic approaches in . Phenotypic analysis of the mutants showed that the two ERAD pathways additively play negative roles in heat tolerance, which was demonstrated by higher survival rate and lower electrolyte leakage in the loss of function mutants compared to the wild type plants. Importantly, gene expression analysis revealed that the mutant plants showed elevated transcriptional regulation of several downstream genes, including those encoding CPR and UPR marker genes, under both basal and heat stress conditions. Finally, multiple components of ERAD genes exhibited rapid response to increasing temperature. Taken together, our data not only unravels key insights into the crosstalk between different protein quality control processes, but also provides candidate genes to genetically improve plant heat tolerance in the future.
    Keywords: Cer9 ; Hrd1 ; Erad ; Heat Stress Response ; Cytosolic Protein Response ; Unfolded Protein Response ; Biology ; Chemistry ; Anatomy & Physiology
    ISSN: 0006-291X
    E-ISSN: 1090-2104
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  • 6
    Language: English
    In: The Journal of organic chemistry, 15 March 2013, Vol.78(6), pp.2710-4
    Description: A palladium-catalyzed cyanation of aryl halides and borons has been developed by employing cuprous thiocyanate as a safe cyanide source. This protocol avoids the use of a highly toxic cyanide source, providing aromatic nitriles in moderate to good yields with good functional tolerance.
    Keywords: Halogens -- Chemistry ; Nitriles -- Chemical Synthesis ; Palladium -- Chemistry ; Thiocyanates -- Chemistry
    ISSN: 00223263
    E-ISSN: 1520-6904
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  • 7
    Language: English
    In: Brain Research, 15 December 2017, Vol.1677, pp.86-92
    Description: The neurotoxicity of amyloid-β peptide (Aβ), a predominant histopathological hallmark lesion of Alzheimer’s disease (AD), is enhanced by iron, as found in amyloid plaques of Alzheimer’s disease (AD) patients. We investigated whether deferoxamine (DFX) treatment promotes functional recovery and tissue repair in APP/PS1 double transgenic mice. Twelve-month-old APP/PS1 mice were randomly divided into two groups (APP/PS1 and DFX). Neurological deficits were monitored for 2 weeks following DFX treatment. To characterize the activation of the microglia, expression of the M1 and M2 phenotypes was analyzed by immunohistochemistry and immunoblotting. Moreover, deposition of iron and Aβ, as well as apoptosis, were examined, and a behavioral test was performed. DFX significantly ameliorated cognitive function and deposition of Aβ as well as inhibited apoptosis in the brain. Consistent with these observations, DFX induced M2 activation of microglia and inhibited M1 activation of microglia in the hippocampus of APP/PS1 mice. In conclusion, DFX treatment improved functional recovery of AD mice, and the mechanism may involve DFX-induced M2 activation of microglia.
    Keywords: Deferoxamine ; Alternative Activation ; Microglia ; Amyloid Beta Deposits ; Alzheimer Disease ; Anatomy & Physiology
    ISSN: 0006-8993
    E-ISSN: 1872-6240
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  • 8
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 2010, Vol.107(17), pp.7993-7998
    Description: Injury stimulates neurogenesis in the adult brain, but the role of injury-induced neurogenesis in brain repair and recovery is uncertain. One strategy for investigating this issue is to ablate neuronal precursors and thereby prevent neurogenesis, but this is difficult to achieve in a specific fashion. We produced transgenic mice that express herpes simplex virus thymidine kinase (TK) under control of the promoter for doublecortin (Dcx), a microtubule-associated protein expressed in newborn and migrating neurons. Treatment for 14 days with the antiviral drug ganciclovir (GCV) depleted Dcx-expressing and BrdU-labeled cells from the rostral subventricular zone and dentate gyrus, and abolished neurogenesis and associated neuromigration induced by focal cerebral ischemia. GCV treatment of Dcx-TK transgenic, but not WT, mice also increased infarct size and exacerbated postischemic sensorimotor behavioral deficits measured by rotarod, limb placing, and elevated body swing tests. These findings provide evidence that injury-induced neurogenesis contributes to stroke outcome and might therefore be a target for stroke therapy. ; Includes references ; p. 7993-7998.
    Keywords: Neurogenesis -- Health Aspects ; Stroke -- Risk Factors ; Brain Injuries -- Complications And Side Effects;
    ISSN: 0027-8424
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  • 9
    Language: English
    In: Journal of the American College of Cardiology, 01 April 2014, Vol.63(12), pp.S193-S193
    Description: [Clinical Information] Patient initials or identifier number C.H. TSAI Relevant clinical history and physical exam 72-year-old man DM, hypertension, hyperlipidemia, smoker Discordance of blood pressure between two arms for many years(30-40 mmHg) Dizziness during postural change in recent 3-4 months [Interventional...
    Keywords: Medicine
    ISSN: 0735-1097
    E-ISSN: 1558-3597
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  • 10
    Language: English
    In: Journal of Applied Mathematics and Computing, 2013, Vol.42(1), pp.339-350
    Description: Let P ∈ℂ m × m and Q ∈ℂ n × n be Hermitian and { k +1}-potent matrices, i.e., P k +1 = P = P ∗ , Q k +1 = Q = Q ∗ , where (⋅) ∗ stands for the conjugate transpose of a matrix. A matrix X ∈ℂ m × n is called { P , Q , k +1}-reflexive (anti-reflexive) if PXQ = X ( PXQ =− X ). In this paper, the matrix equation AXB = C subject to { P , Q , k +1} reflexive and anti-reflexive constraints are studied by converting into two simpler cases: k =1 and k =2. The solvability conditions and the general solution are obtained, and then the maximal and minimal ranks among the solutions are derived. Finally, the associated optimal approximation problem for a given matrix is considered.
    Keywords: Matrix equation ; Potent matrix ; {,,+1}-reflexive (anti-reflexive) matrix ; Rank ; Optimal approximation
    ISSN: 1598-5865
    E-ISSN: 1865-2085
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