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101.
102.
Development of headspace SPME method for analysis of volatile organic compounds present in human biological specimens 总被引:2,自引:0,他引:2
In recent years, interest has increased regarding the identification of volatile organic compounds (VOCs) for metabolic profiling,
human scent identification of the living and deceased, and diagnostic potentials for certain diseases that are known for its
association with distinct odor. In this study, a method has been developed that is capable of sampling, identifying, and differentiating
the VOCs present in various biological specimens of forensic importance (blood, breath, buccal cells, and urine) taken from
the same individuals. The developed method requires a pretreatment step to remove targeted VOCs from the sampling apparatus
prior to sampling of the individual specimens. The VOCs collected from the biological specimens were characterized by solid-phase
microextraction and gas chromatography/mass spectrometry with ratios of the most abundant and frequent VOCs compared using
qualitative and semiquantitative methods. Blood, breath, and buccal cells required extraction procedures ranging from 18 to
21 h in order to optimize the limit of detection, which averaged 5–15 ng across these specimens. The optimal method for measuring
urine VOCs was complete in less than an hour; however, the limit of detection was higher with a range of 10–40 ng quantifiable.
The demonstrated sensitivity and reproducibility of the methods developed allow for population studies of human scent VOCs
from various biological specimen collection kits used in the forensic and clinical fields. 相似文献
103.
Loosely aggregated conjugated polymer nanoparticles (CPNs) were used as nontoxic and efficient small interfering RNA (siRNA) delivery vehicles with delivery visualization. A significant down regulation (94%) of a target gene was achieved by transfection of HeLa cells with the CPNs/siRNA complexes, supporting CPN as a promising siRNA delivery carrier. 相似文献
104.
J. Arturo Mendez Navarro Elena I. Kaikina Héctor F. Ruiz Leonardo Guardado Z. Alejandro Castellanos 《Nonlinear Analysis: Real World Applications》2011,12(4):2077-2090
In this work, an analytic development for a transmission line with a corona effect for simulating an electromagnetic transient is presented. The asymptotic solution for the Radulet equations in which a nonlinear term is presented is obtained. The study is carried out for a single-phase transmission line. The electrical parameters for an overhead line are defined and several formulations for their calculation are presented. The frequency dependence of the electrical parameters is considered. In the first part, the linear problem solution is found; the Fourier and Laplace transforms are applied with respect to distance and time respectively. After finding the solution in the Fourier–Laplace domain, which is expressed in terms of a Green’s function integral, an approximate analytical solution is obtained in the distance–time domain by means of asymptotic methods. Finally, the nonlinear solution is found using as a first approach the linear solution. The results obtained show an attenuation in the voltage wave due to the corona effect. 相似文献
105.
Tereza Vokatá Megan Twomey Eladio Mendez Joong Ho Moon 《Journal of polymer science. Part A, Polymer chemistry》2015,53(11):1403-1412
A series of flexible, highly bright fluorescent poly(p‐phenyleneethynylene)s (PPEs) was prepared by employing a disulfide containing nonconjugated monomer at various ratios under Sonogashira reaction conditions. PPEs with flexible linkers exhibited fluorescence properties comparable to those of a fully conjugated PPE when less than 50% of flexible monomers were incorporated into the backbone. To evaluate the self‐assembly properties of PPEs, a series of conjugated polymer nanoparticles (CPNs) was fabricated by treating PPEs with organic acids followed by dialysis. CPNs containing linkers exhibited different complexation behavior with polysaccharides, warranting further investigation into how flexibility and biodegradability of CPNs influence their cellular interaction and entry. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1403–1412 相似文献
106.
Following Brown (Phys Rev D79:104029, 2009), in this paper we give an overview of how to modify standard hyperbolic formulations of the 3+1 evolution equations of General
Relativity in such a way that all auxiliary quantities are true tensors, thus allowing for these formulations to be used with
curvilinear sets of coordinates such as spherical or cylindrical coordinates. After considering the general case for both
the Nagy–Ortiz–Reula and the Baumgarte–Shapiro–Shibata–Nakamura (BSSN) formulations, we specialize to the case of spherical
symmetry and also discuss the issue of regularity at the origin. Finally, we show some numerical examples of the modified
BSSN formulation at work in spherical symmetry. 相似文献
107.
Ana Catarina Lopes Dr. Sonia A. C. Carabineiro Prof. Manuel Fernando R. Pereira Prof. Gabriela Botelho Prof. Senentxu Lanceros‐Mendez 《Chemphyschem》2013,14(9):1926-1933
This paper describes the processing of silver‐nanoparticle‐doped poly(vinylidene fluoride). The effects of the concentration and size of the filler on the electroactive phase of the polymer and the optical and electrical properties are discussed. Spherical silver nanoparticles incorporated into the poly(vinylidene fluoride) polymeric matrix induce nucleation of the electroactive γ phase. The electroactive phase content strongly depends on the content and size of the nanoparticles. In particular, there is a critical nanoparticle size, below which the filler losses its nucleation efficiency due to its small size relative to that of the polymer macromolecules. Furthermore, the presence of surface plasmon resonance absorption in the composites is observed, which once again shows a strong dependence on the concentration and size of the particles. The absorption is larger for higher concentrations, and for a given concentration increases with particle size. This behavior is correlated to the electrical response and is related to the extra bands and electrons provided by the nanoparticles in the large energy band gap of the polymer. 相似文献
108.
109.
We have calculated the energy and lineshape of the 1s → 2px,y transition for a hydrogenic impurity located in a quantum well. Due to the dependence of the transition energy on the impurity location, the absorption lineshape is very sensitive to the doping profile. The spectrum, in general, exhibits two peaks, arising from impurities located near the center and the edges of the well. 相似文献
110.
We discuss a recently proposedSO(10) v ×SO(10) H grand unified-extended technicolour model. Because proton decay is probably too fast in this model, we study the other possible models based onSO(10) v ×SO(10) H . As a result of this analysis only a few of these models could possibly be realistic, they would be slight modifications of that previously proposed. None of them predicts the expected value forΛ TC, it must be adjusted by introducing another mass scale. In these models ordinary fermion masses tend to be too small. 相似文献