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171.
Sabina Prilutsky Eyal Zussman Yachin Cohen 《Journal of Polymer Science.Polymer Physics》2010,48(20):2121-2128
Composite nanofibers with 5% w/w multiwalled carbon nanotubes (MWCNTs) in polyacrylonitrile (PAN) were fabricated using the electrospinning technique. Morphological development during the carbonization process was characterized by transmission electron microscopy (TEM) with in situ heating. It was found that the orientation of graphitic layers increases with temperature and does not change significantly with time during our TEM measurement, except the 750 °C. In the heating stage at 750 °C noticeable enhancement of orientation with time was observed. The presence of embedded CNTs enhances the order of the formed graphitic structures even when the CNTs are irregular or entangled. The results indicate that embedded MWCNTs in the PAN nanofibers nucleate the growth of carbon crystals during PAN carbonization. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010 相似文献
172.
Sabina‐Alexandra Filimon Cristian G. Hrib Sören Randoll Ion Neda Peter G. Jones Matthias Tamm Prof. Dr. 《无机化学与普通化学杂志》2010,636(5):691-699
Two new optically active bidentate N,N‐ligands, DMIQCI ( 3a ) and DMIQCD ( 3b ), containing a quinuclidine core and an imidazolidin‐2‐imine unit, were synthesized. The reaction of these ligands with [(η5‐C5Me5)RuCl]4 afforded the brick‐red ruthenium(II) complexes [(η5‐C5Me5)Ru(DMIQCI)Cl] ( 4 ) and [(η5‐C5Me5)Ru(DMIQCD)Cl] ( 5 ), which were used as catalysts in the transfer hydrogenation of acetophenone in boiling 2‐propanol. The reactions of 3a and 3b with [(COD)PdCl2] (COD = 1,5‐cycloocta‐diene) and with [(DME)NiBr2] (DME = 1,2‐dimethoxyethane) afforded the square‐planar palladium(II) complexes [(DMIQCI)PdCl2] ( 7 ) and [(DMIQCD)PdCl2] ( 8 ) or the tetrahedral nickel(II) complexes [(DMIQCI)NiBr2] ( 9 ) and [(DMIQCD)NiBr2] ( 10 ), respectively. The X‐ray crystal structures of 4 , 7 , 9· THF, and 10 are reported. 相似文献
173.
Eduardo López-López Federico J. Sabina Raúl Guinovart-Díaz Julián Bravo-Castillero Reinaldo Rodríguez-Ramos 《Journal of Electrostatics》2013,71(4):791-800
Simple closed-form expressions for effective permittivity of fiber-reinforced composites with transversely isotropic constituents are found using asymptotic homogenization. Circular cylindrical fibers are distributed in a square array. The analysis considers four orientations of constituents transverse symmetry axis relative to fibers direction. Local problems defined on a periodic square unit cell are solved by means of complex potential theory using Weierstrassian and Natanzon's functions, assuming that the contrast of permittivities is small. Derived closed-form formulas are compared with finite element calculations and, in the isotropic case, with standard mixture rules and classical bounds, obtaining excellent results even when contrast is large. 相似文献
174.
Sabina Alazzawi 《Letters in Mathematical Physics》2013,103(1):37-58
Considering the model of a scalar massive Fermion, it is shown that by means of deformation techniques it is possible to obtain all integrable quantum field theoretic models on two-dimensional Minkowski space which have factorizing S-matrices corresponding to two-particle scattering functions S 2 satisfying S 2(0) = ?1. Among these models there is for example the Sinh-Gordon model. Our analysis provides a complement to recent developments regarding deformations of quantum field theories. The deformed model is investigated also in higher dimensions. In particular, locality and covariance properties are analyzed. 相似文献
175.
DNA and synthetic polynucleotides modified with a complex of osmium tetroxide with 2,2'-bipyridine (Os,bipy) produce specific voltammetric signals at pyrolytic graphite electrodes. Based on a sufficient potential separation between the peaks of Os,bipy-modified DNA (DNA-Os,bipy) and of free Os,bipy, and using an adsorptive transfer stripping voltammetric procedure involving extraction of free Os,bipy from the electrode by chloroform, DNA-Os,bipy can be determined in an excess of the free reagent. Under certain conditions, 140 pg of DNA-Os,bipy can be detected after a 5 min accumulation period. This analysis displays a more favorable sensitivity and a better selectivity for DNA structure than oxidation of DNA guanine moieties, and offers detection of osmium DNA markers at carbon electrodes. 相似文献
176.
Preconception care, a long-established concept for primary prevention of maternal and perinatal morbidity and mortality through detection and reduction of modifiable risks, has been widely propagated for the last decades. This article provides an overview of the various goals and practices described in the literature in different parts of the world, including issues and controversies pertaining to the provision and implementation of preconception care in different health care settings. 相似文献
177.
Jorge Ize Roland England Federico J. Sabina 《Annali di Matematica Pura ed Applicata》1986,146(1):31-63
Summary The two dimensional problem of diffraction of scalar waves by a bounded inhomogeneity in an otherwise unbounded medium is studied both theoretically and numerically. Using singular operator properties, existence and uniqueness of the solution, and the convergence of the numerical method used are proved. 相似文献
178.
Mixed manganese iron oxides (Mn/Fe/O) as heterogeneous catalysts were prepared by hydrothermal treatment and citrate methods to be tested in the oxidation of p-xylene (PX) using as oxidation agent molecular oxygen, hydrogen peroxide, and tert-butyl hydroperoxide. Preparation of mixed MnFe oxide by the citrate method releases materials with smaller particle size and lower degree of crystallinity as compared with the hydrothermal one, which further leads to a higher activity toward the oxidation of PX. A conversion of PX of 98% and a yield in p-toluic acid of 93% were obtained in the presence of Mn/Fe/O prepared by the citrate method using tert-butyl hydroperoxide as an oxidizing agent. 相似文献
179.
Strano-Rossi S Molaioni F Rossi F Botrè F 《Rapid communications in mass spectrometry : RCM》2005,19(11):1529-1535
This paper describes a rapid gas chromatographic/mass spectrometric (GC/MS) screening method for the detection of drugs of abuse and/or their metabolites in urine. Synthetic stimulants, opiates, cocaine metabolites, cannabinoids--and specifically the acid metabolite of tetrahydrocannabinol (THC-COOH)--can be simultaneously extracted by a single liquid/liquid separation step, at alkaline pH, and assayed as trimethylsilyl derivatives by GC/MS in SIM (selected ion monitoring) mode. All the analytes show a good linearity (R2 > 0.99 for most of the considered substances) in the range 25-1000 ng/mL, with a good reproducibility of both the retention times (CV% <0.7) and the relative abundances of the characteristic diagnostic ions (CV% <13). The limit of detection (LOD) of the method is 25 ng/mL of target compound in human urine for most of the substances investigated, 3 ng/mL for THC-COOH, and 10 ng/mL for norbuprenorphine. Validation of the method allows its application to different fields of forensic analytical toxicology, including antidoping analysis. 相似文献
180.
The leakage of aqueous contents of neutral (dipalmitoylphosphatidylcholine/cholesterol) liposomes as induced by Rz1, a proline-rich lipoprotein, the bacteriophage Rz1 gene product, was studied. Fluorescence enhancement assay with Tb3+/dipicolinic acid and self-quenching assays with carboxyfluorescein and fluorescein isothiocyanaten-dextran were used to monitor the Rz1-induced leakage from neutral liposomes. The results demonstrated that Rz1 caused local membrane destabilization leading to the leakage of the liposome contents. The extent of the leakage was independent of the molecular mass of the liposome-entrapped solutes in the range of 376–4000 Da. The kinetics of Rz1-liposome leakage was very similar to that obtained with detergent Triton X-100 for all the solutes used. The results suggested that Rz1 can act as a detergent; i.e., by interacting with lipids on both sides of the liposome membranes (inducing perturbation in the lipid packing within the bilayer), it facilitates the transfer of encapsulated molecules into the external liposome environment. The importance of this result for Rz1 physiological function is discussed. 相似文献