bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ammonia and Dinitrogen Activation by Surface Organometallic Chemistry on Silica‐Grafted Tantalum Hydrides
Authors: Chow Catherine , Taoufik Mostafa , Quadrelli Elsje Alessandra 
Published: February 2011

AbstractAmmonia N–H bond activation and dinitrogen N≡N cleavage with dihydrogen on an isolated metal atom have been achieved with the silica‐grafted TaIII and TaV hydrides [(≡SiO)2TaH] (2a) and [(≡SiO)2TaH3] (2b), accessed through surface organometallic chemistry (SOMC). The synthesis of the starting tantalum hydrides 2a and 2b by grafting tris(neopentyl)neopentylidenetantalum(V), Ta(=CH–tBu)Np3, on silica yields well‐defined, isolated tantalum atoms. Silsesquioxane molecular modelling shows that the mechanism of the grafting reaction implies a tetraalkyl intermediate [(≡SiO)TaNp4]. The starting hydrides 2a and 2b react stoichiometrically and catalytically with alkanes in reactions such as alkane metathesis, cross‐metathesis between ethane and toluene, and methane coupling to form ethane. Mechanistic studies show the relevance of tantalum carbenes and Chauvin‐like metallacyclobutane intermediates in most of these reactions. Finally, the stoichiometric N2 cleavage and NH3 activation to the final imido amido tantalum(V) complex [(≡SiO)2Ta(NH)(NH2)] (3) are reviewed and discussed mechanistically. In the N≡N cleavage reaction, dihydrogen adducts on silica‐grafted isolated tantalum atoms appear to play a central role. The ammonia reaction occurs by bifunctional activation through the Lewis acid/Lewis base couple formed by a metal centre and a coordinated nitrogen atom, the so‐called “NH effect”. Such bifunctional activation is also observed for the heterolytic cleavage of H2 by [(≡SiO)2Ta(NH)(NH2)] (3).
Vertically Well‐Aligned In2O3 Cone‐Like Nanowire Arrays Grown on Indium Substrates
Authors: Yin Wenyan , Doty Matt , Ni Chaoying , Hu Changwen , Cao Minhua , Wei Bingqing 
Published: February 2011

AbstractSingle‐crystalline, cone‐like In2O3 nanowire (NW) arrays were directly synthesized on the surface of indium grains without any catalyst by using a simple chemical vapor deposition (CVD) method. The indium grains served both as the indium source, which reacted with different oxygen sources, and the substrate for the growth of the cone‐like In2O3 NW arrays. The controllable synthesis of the cone‐like In2O3 NW arrays with variable densities, sizes, and morphologies were achieved by adjusting the oxygen sources. A possible mechanism was proposed for the formation of the cone‐like In2O3 NW arrays. The photoluminescence spectrum of the low‐density, cone‐like In2O3 NW arrays shows emission in a wide range, from the visible (yellow light) into the near infrared region.
Ring‐Shaped J‐Type and Star‐Shaped H‐Type Nanostructures of an Unsymmetrical (Phthalocyaninato)zinc Complex
Authors: Tian Naichang , Ma Pan , Wang Quanbo , Zhang Xianyao , Jiang Jianzhuang , Bai Ming 
Published: February 2011

AbstractUnsymmetrical (phthalocyaninato)zinc complex 1 was synthesized by transesterification and self‐assembled into ring‐shaped nanostructures with J‐type aggregation at the chloroform/water interface and into star‐shaped nanostructures with H‐type aggregation in the chloroform/methanol system, respectively. Its self‐assembly properties have been studied by spectroscopic, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) techniques. The star‐shaped nanostructures were found to have better semiconducting properties than the ring‐shaped nanostructures due to the more effective intermolecular π‐electron delocalization. The results appear to represent the first example of nanostructures with J‐ and H‐type molecular conformations self‐assembled from the same phthalocyanine compound in different solvent systems with novel ring‐ and star‐shaped morphologies, respectively.
Influence of N‐Substitution on the Oxidation of 2‐Pyridylmethylamines with Bis(trimethylsilyl)amides of Iron(III) – Synthesis of Heteroleptic Iron(II) 2‐Pyridylmethylamides
Authors: Malassa Astrid , Schulze Benjamin , Stein‐Schaller Brigitte , Görls Helmar , Weber Birgit , Westerhausen Matthias 
Published: February 2011

AbstractThe reaction of (thf)Fe[N(SiMe3)2]2Cl with (2‐pyridylmethyl)(diphenylphosphanyl)amine (1) in hot tetrahydrofuran (THF) yields dinuclear [(ClFe)2{μ‐N(SiMe3)2}{Ph2P(NCH2Py)2}] (2) and [ClFe{Ph2P(O)‐NCH2Py}]2 (3) with the oxygen atom stemming from THF degradation. The formation of 2 requires a P–N bond cleavage and reformation leading to the tetradendate diphenyl‐bis(2‐pyridylmethylamido)phosphonium ion. If this reaction of (thf)Fe[N(SiMe3)2]2Cl with 1 is performed at room temperature, no P–N bond cleavage is observed. Instead of that, ether degradation occurs yielding [Fe4(μ4‐O)(μ2‐Cl)2(Ph2P‐NCH2Py)4] (4) with a central oxygen‐centered iron tetrahedron as well as complex 3. Recrystallization of 3 from dichloromethane leads to addition of HCl and to the formation of [FeCl2·{Ph2P(O)‐N(H)‐CH2Py}] (5). The phosphonium ion of 2 is isoelectronic to the corresponding diphenyl‐bis(2‐pyridylmethylamino)silane (6). Lithiation of 6 followed by a metathetical reaction with (thf)2FeCl2 yields the trinuclear complex [Fe3Cl2{Ph2Si(NCH2Py)2}2] (7) with antiferromagnetic interactions.
Discrete Molecular Squares {[(en)M(CN)]4}4+ Derived from [(en)M(CN)2] (M = PtII, PdII)
Authors: Galstyan Anzhela , Sanz Miguel Pablo J. , Wolf Jacqueline , Freisinger Eva , Lippert Bernhard 
Published: February 2011

AbstractC2h‐symmetrical tetranuclear metallacycles {[M(en)(CN)]4}(NO3)4 with M = PdII (4) and PtII (5) have been prepared upon reacting M(en)(CN)2 [M = PdII (1), PtII (2)] with [M(en)(H2O)2](NO3)2. Replacement of the nitrate anions of 5 by terephthalate anions yields the corresponding salt 5a. The X‐ray crystal structures of 1, 4, 5, and 5a have been determined. In the metallacycles 4, 5, and 5a the four metals form almost ideal squares with average M···M distances of ca. 5.05 Å (5, 5a) and 5.08 Å (4) along the sides. As shown by 1H NMR spectroscopy, the Pt square 5 is stable in aqueous solution, whereas the Pd square 4 undergoes rearrangement reactions upon aging or the presence of other Pd species such as (bpy)PdII. Preliminary studies on the possibility of non‐covalent interactions of 4 and 5 with model nucleobases in water reveal that only 5 is useful in this respect. According to the concentration‐dependence 1H NMR study, there is an interaction with the purine base 9‐ethyladenine, molecular details of which are unclear at this stage, however. Compound 4 is substitutionally labile and is transformed into the coordination compound 8 with 1‐methylcytosine. Two more side products, produced during the various reactions carried out, were characterized by X‐ray crystallography: [Pt(en)2][Pt(CN)4] (3) and [Pd(bpy)(en)](SO4)·3H2O (7).
Synthesis and Reactivity of a New Oxidation‐Labile Heterobimetallic Mn6Zn2 Carbamate Cluster and Precursor to Nanosized Magnetic Oxide Particles
Authors: Domide Dan , Hübner Olaf , Behrens Silke , Walter Olaf , Wadepohl Hubert , Kaifer Elisabeth , Himmel Hans‐Jörg 
Published: February 2011

AbstractThe synthesis and characterization of the new octanuclear mixed carbamate complex [Zn2Mn6(μ4‐O)2(O2CN(iPr)2)12] is reported. This complex is readily oxidized by O2 to give [Zn2Mn6(μ4‐O)2(μ3‐O)(O2CN(iPr)2)12] featuring a central O atom statistically distributed over two sites within the void of the inner Mn6 cage of the carbamate complex. In relation to the situation before oxidation, the metal cage is expanded by a change of the carbamate bonding mode. The two carbamate complexes were used as precursors to magnetic oxide nanoparticles under mild conditions (210–270 °C depending on the heating rate). A mixture of crystalline ZnMn2O4 and MnO nanoparticles resulted. The experimental data are complemented by some quantum chemical (DF) calculations.
Synthesis of Chiral Furopyrrolizidinones through a Key Tandem Cope Elimination/1,3‐Dipolar Cycloaddition Reaction of Tricyclic Lactones
Authors: Li Yu‐Jang , Chuang Hsiang‐Yu , Yeh Shang‐Ming , Huang Weng‐Sang 
Published: February 2011

AbstractHighly functionalized chiral furo‐pyrrolizidinones containing contiguous quaternary centers were synthesized in moderate to good yields by treatment of various hexahydro‐3,4‐dioxa‐8a‐aza‐as‐indacen‐2‐ones with m‐CPBA under basic conditions through a tandem Cope elimination/1,3‐dipolar cycloaddition reaction sequence, followed by N–O cleavage and lactam ring cyclization.
Economic and technical management of an aggregation agent for electric vehicles: a literature survey
Authors: Bessa Ricardo J. , Matos Manuel A. 
Published: February 2011

SUMMARYThe foreseeable increase in the use of electric vehicles (EV) led to the discussion on intermediate entities that could help manage a great number of EV. An aggregation agent for electric vehicles is a commercial middleman between a system operator (SO) and plug‐in EV. From the SO perspective, the aggregator is seen as a large source of generation or load, which could provide ancillary services such as spinning and regulating reserve. Generally, these services will be provided in the day‐ahead and intraday electricity markets. In addition, the aggregator also participates in the electricity market with supply and demand energy bids. This paper provides a comprehensive bibliographic survey on the aggregator role in the power system operation and electricity market. The scope of the survey covers 59 references divided in journal, conference proceedings, thesis, research papers, and technical reports published after 1994. These papers are put into several technical categories: electricity market and EV technical and economic issues; aggregation agent concept, role and business model; algorithms for EV management as a load/resource. Copyright © 2011 John Wiley & Sons, Ltd.
A new time‐domain based power system frequency estimation algorithm
Authors: Seyedi Heresh , Sanaye‐Pasand Majid 
Published: February 2011

SUMMARYFrequency stability is one of the most important features of power systems. It is closely dependent on the value of system frequency. In the present day modern power systems, fast and accurate frequency estimation has become quite vital. Any mistake in accurate estimation of frequency may threaten the frequency stability or at least lead to system operation problems. In this paper, a new time‐domain based power system frequency estimation algorithm is proposed. Different abnormal events such as frequency decline due to load‐generation mismatch are modeled and ability of the new frequency measurement technique to track the frequency is tested. Performance of the new method is evaluated and compared with an existing frequency estimation algorithm. Simulation results confirm advantages of the new approach over the existing method. Copyright © 2011 John Wiley & Sons, Ltd.
Variational data assimilation using targetted random walks
Authors: Cotter S. L. , Dashti M. , Stuart A. M. 
Published: February 2011

AbstractThe variational approach to data assimilation is a widely used methodology for both online prediction and for reanalysis. In either of these scenarios, it can be important to assess uncertainties in the assimilated state. Ideally, it is desirable to have complete information concerning the Bayesian posterior distribution for unknown state given data. We show that complete computational probing of this posterior distribution is now within the reach in the offline situation. We introduce a Markov chain–Monte Carlo (MCMC) method which enables us to directly sample from the Bayesian posterior distribution on the unknown functions of interest given observations. Since we are aware that these methods are currently too computationally expensive to consider using in an online filtering scenario, we frame this in the context of offline reanalysis. Using a simple random walk‐type MCMC method, we are able to characterize the posterior distribution using only evaluations of the forward model of the problem, and of the model and data mismatch. No adjoint model is required for the method we use; however, more sophisticated MCMC methods are available which exploit derivative information. For simplicity of exposition, we consider the problem of assimilating data, either Eulerian or Lagrangian, into a low Reynolds number flow in a two‐dimensional periodic geometry. We will show that in many cases it is possible to recover the initial condition and model error (which we describe as unknown forcing to the model) from data, and that with increasing amounts of informative data, the uncertainty in our estimations reduces. Copyright © 2011 John Wiley & Sons, Ltd.
Implicit finite element schemes for the stationary compressible Euler equations
Authors: Gurris Marcel , Kuzmin Dmitri , Turek Stefan 
Published: February 2011

SUMMARYA semi‐implicit finite element scheme and a Newton‐like solver are developed for the stationary compressible Euler equations. Since the Galerkin discretization of the inviscid fluxes is potentially oscillatory and unstable, the troublesome antidiffusive part is constrained within the framework of algebraic flux correction. A generalization of total variation diminishing (TVD) schemes is employed to blend the original Galerkin scheme with its nonoscillatory low‐order counterpart. Unlike standard TVD limiters, the proposed limiting strategy is fully multidimensional and readily applicable to unstructured meshes. However, the nonlinearity and nondifferentiability of the limiter function makes efficient computation of stationary solutions a highly challenging task, especially in situations when the Mach number is large in some subdomains and small in other subdomains. In this paper, a semi‐implicit scheme is derived via a time‐lagged linearization of the Jacobian operator, and a Newton‐like method is obtained in the limit of infinite CFL numbers. Special emphasis is laid on the numerical treatment of weakly imposed characteristic boundary conditions. A boundary Riemann solver is used to avoid unphysical boundary states. It is shown that the proposed approach offers unconditional stability, as well as higher accuracy and better convergence behavior than algorithms in which the boundary conditions are implemented in a strong sense. The overall spatial accuracy of the constrained scheme and the benefits of the new boundary treatment are illustrated by grid convergence studies for 2D benchmark problems. Copyright © 2011 John Wiley & Sons, Ltd.
Comparing costs and outcomes across programmes of health care
Authors: Martin Stephen , Rice Nigel , Smith Peter C. 
Published: February 2011

SUMMARYThis paper examines the expenditure choices of local health authorities operating under fixed budget constraints. It applies a theoretical model of budgeting to a data set from 303 English Primary Care Trusts (PCTs) across ten broad programmes of health care to derive estimates of the elasticity of expenditure in each programme with respect to the total income of the PCT. The results suggest quite similar income elasticities across most programmes, in the range 0.644–1.128. The only outlier is the musculoskeletal programme with an elasticity of about 0.46. The modelling also derives estimates of spending elasticities with respect to medical needs and thereby permits calculation of the implicit cost of saving a life year in five programmes of care. The results are important as they indicate to policy makers how specific programme areas might be affected by general budgetary reductions. Copyright © 2011 John Wiley & Sons, Ltd.
Randomized comparison of reduced fat and reduced carbohydrate hypocaloric diets on intrahepatic fat in overweight and obese human subjects
Authors: Haufe Sven , Engeli Stefan , Kast Petra , Böhnke Jana , Utz Wolfgang , Haas Verena , Hermsdorf Mario , Mähler Anja , Wiesner Susanne , Birkenfeld Andreas L. , Sell Henrike , Otto Christoph , Mehling Heidrun , Luft Friedrich C. , Eckel Juergen , Schulz-Menger Jeanette , Boschmann Michael , Jordan Jens 
Published: February 2011

Abstract

Obesity-related hepatic steatosis is a major risk factor for metabolic and cardiovascular disease. Fat reduced hypocaloric diets are able to relieve the liver from ectopically stored lipids. We hypothesized that the widely used low carbohydrate hypocaloric diets are similarly effective in this regard. A total of 170 overweight and obese, otherwise healthy subjects were randomized to either reduced carbohydrate (n = 84) or reduced fat (n = 86), total energy restricted diet (−30% of energy intake before diet) for 6 months. Body composition was estimated by bioimpedance analyses and abdominal fat distribution by magnetic resonance tomography. Subjects were also submitted to fat spectroscopy of liver and oral glucose tolerance testing. In all, 102 subjects completed the diet intervention with measurements of intrahepatic lipid content. Both hypocaloric diets decreased body weight, total body fat, visceral fat, and intrahepatic lipid content. Subjects with high baseline intrahepatic lipids (>5.56%) lost ≈7-fold more intrahepatic lipids compared with those with low baseline values (<5.56%) irrespective of diet composition. In contrast, changes in visceral fat mass and insulin sensitivity were similar between subgroups, with low and high baseline intrahepatic lipids.

Conclusion:

A prolonged hypocaloric diet low in carbohydrates and high in fat has the same beneficial effects on intrahepatic lipid accumulation as the traditional low-fat hypocaloric diet. The decrease in intrahepatic lipids appears to be independent of visceral fat loss and is not tightly coupled with changes in whole body insulin sensitivity during 6 months of an energy restricted diet. (HEPATOLOGY 2011)
Osteoblast‐secreted factors enhance the expression of dysadherin and CCL2‐dependent migration of renal carcinoma cells
Authors: Schüler Yvonne , Lee‐Thedieck Cornelia , Geiger Konstanze , Kaiser Tatjana , Ino Yoshinori , Aicher Wilhelm K. , Klein Gerd 
Published: February 2011

AbstractRenal cell carcinoma (RCC) frequently metastasizes to the bone marrow. These metastases are characterized by extensive osteolytic lesions. The mechanism, however, by which RCC cells metastasize to bone marrow remains poorly understood. To unravel the role of bone marrow cells in this context, we performed cell adhesion and migration assays using human RCC cell lines to analyze the influence of resident bone marrow cells on renal tumor cells. The strongest adhesion of RCC cells was observed to osteoblasts. Moreover, conditioned medium of osteoblasts (OB‐CM) significantly increased RCC cell migration. By gene expression analysis dysadherin was identified as a transcript whose expression could be elevated more than twofold in RCC cells when exposed to OB‐CM. Suppression of dysadherin expression in RCC cells by siRNA reduced their ability to migrate in the presence of OB‐CM. Furthermore, the RCC cells secreted high amounts of the chemokine CCL2 when tumor cells migrated under the influence of osteoblast‐secreted factors. CCL2 neutralization strongly reduced the migratory ability of the RCC cells. Silencing the expression of dysadherin in RCC cells resulted in a twofold reduction of CCL2 protein expression indicating a dysadherin‐dependent expression of the chemokine. Taken together, our data show that osteoblasts are the major cell type of the bone marrow that affect RCC cells by secreting factors that increase the expression of dysadherin and CCL2 in the tumor cells leading to enhanced cell migration. These data suggest an osteoblast‐induced autocrine mechanism for a facilitated homing of RCC cells to the bone marrow.
Spectrin αII and βII tetramers contribute to platinum anticancer drug resistance in ovarian serous adenocarcinoma
Authors: Maeda Osamu , Shibata Kiyosumi , Hosono Satoyo , Fujiwara Sawako , Kajiyama Hiroaki , Ino Kazuhiko , Nawa Akihiro , Tamakoshi Koji , Kikkawa Fumitaka 
Published: February 2011

AbstractTo overcome drug resistance in ovarian carcinoma, novel resistance mechanisms must be elucidated for clinical application. We purified 2 proteins in the 300 kDa range from cisplatin‐resistant cells (NOS2CR2) by affinity chromatography with cisplatin‐exposed Glutathione Sepharose 4B. The purified proteins were identified as spectrin αII and βII by peptide mass mapping analysis. Western blot analysis detected greater expression of spectrin αII and βII in NOS2CR2 than in wild‐type cells (NOS2). The same result was obtained for spectrin βII expression by immunohistochemical staining. To determine whether spectrin αII and βII contribute to resistance, a drug sensitivity test was performed on SKOV3 ovarian cancer cells transfected with small interfering RNA. Sensitivity to platinum drugs was increased in the expression reduced cells. In a clinical study of five ovarian serous adenocarcinoma cases, tumor specimens taken after treatment with carboplatin stained more strongly for spectrin βII expression than untreated specimens. Fifty‐two tumor specimens from 46 patients with ovarian serous adenocarcinoma were immunohistochemically stained for spectrin βII and scored. Tumors previously treated by chemotherapy scored higher than those not treated. Of 27 cases with detectable residual tumors at the time of surgery, cases scoring 4–6 had shorter progression‐free survival periods after platinum‐based chemotherapy than cases scoring 0–3 (p = 0.012). The cytoskeleton proteins Spectrin αII and βII contributed to drug resistance by anchoring the GS‐Pt complex to the cell membrane, arresting cisplatin activity. Thus spectrin βII may be a useful predictor of platinum sensitivity in ovarian serous adenocarcinoma.
Lower sensitivity of screening mammography after previous benign breast surgery
Authors: van Breest Smallenburg Vivian , Duijm Lucien E.M. , Voogd Adri C. , Groenewoud Johanna H. , Jansen Frits H. , van Beek Mike , Louwman Marieke W.J. 
Published: February 2011

AbstractFew data are available on the effect of previous benign breast surgery on screening mammography accuracy. We determined whether sensitivity of screening mammography and tumor characteristics are different for women with and without previous benign breast surgery. We included a consecutive series of 317,398 screening mammograms of women screened between 1997 and 2008. During 2‐year follow‐up, clinical data, breast imaging, biopsy and surgery reports were collected from women with screen‐detected or interval breast cancers. Screening sensitivity, tumor biology and tumor stages were compared between 168 women with breast cancer and prior ipsilateral benign breast surgery and 2,039 women with breast cancer but without previous ipsilateral, benign breast surgery. The sensitivity of screening mammography was significantly lower for women with prior surgery [64.3% (108/168) versus 73.4% (1,496/2,039), p = 0.01]. The concomitant increased interval cancer risk remained significant after logistic regression adjustment for age and breast density (OR = 1.5, 95% CI: 1.1–2.1). Comparing screen‐detected cancers in women with and without prior breast surgery, no significant differences in estrogen receptor status (p = 0.56), mitotic activity (p = 0.17), proportions of large (T2+) tumors (p = 0.6) or lymph node positive tumors (p = 0.4) were found. Also for interval cancers, no differences were found in estrogen receptor status (p = 0.41), mitotic activity (p = 0.39), proportions of large tumors (p = 0.9) and lymph node positive tumors (p = 0.5) between women with and without prior breast surgery. We conclude that sensitivity of screening mammography is significantly lower in women with previous benign breast surgery than without, but tumor characteristics are comparable both for screen detected cancers and interval cancers.