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981.
Jingsong Sun Lin Liang Jianmin Sun Yanqiu Jiang Kaifeng Lin Xianzhu Xu Runwei Wang 《Catalysis Surveys from Asia》2011,15(1):49-54
This short review presents the recent developments in the direct synthesis of cyclic carbonates from olefins and CO2. The straightforward synthesis of cyclic carbonates from olefins instead of epoxides, also called one-pot “oxidative carboxylation”
of olefins, can be viewed as the coupling of two sequential reactions of epoxidation of olefins and CO2 cycloaddition to epoxides formed. The facile synthetic approach would make carbonate synthesis simpler and even cheaper with
industrial potential from environmental and economic points of view. Some progresses have been made on this direct synthetic
reaction for cyclic carbonates with homogeneous and heterogeneous catalysts, however, this reaction system is still at a preliminary
stage. Among the catalysts reported, only a few can be considered as effective for the direct oxidative carboxylation of olefins
to cyclic carbonates. Thus active and selective catalysts should be explored to put the direct synthesis of cyclic carbonates
into practical applications. 相似文献
982.
Per Malmberg Eva Jennische Daniel Nilsson Håkan Nygren 《Analytical and bioanalytical chemistry》2011,399(8):2711-2718
The use of high-resolution, imaging TOF-SIMS is described and examples are made to demonstrate the application of the method
in medical research. Cytochemistry by TOF-SIMS is shown by localization of diacylglycerol (DG) in cryostat sections of hyaline
cartilage and by localization of corticosterone in cryostat sections of the adrenal gland cortex. Quantitative measurements
and comparison of groups is shown by comparing the lipid content of adipose tissue from two mouse strains, transgenic mouse
expressing the FOXC2 gene and wild-type controls. Finally, biopsies made for histopathological diagnosis of infantile reversible
cytochrome c oxidase deficiency myopathy were analyzed in order to define the chemical content of areas showing a pathological
structure in the light microscope. The use of high-resolution, imaging TOF-SIMS in medical research allows analysis of intact
tissue and probe-free localization of specific target molecules in cells and tissues. The TOF-SIMS analysis is not dependent
on penetration of reagents into the sample and also independent of probe reactivity such as cross-reactivity or background
staining. The TOF-SIMS method can be made quantitative and allows for analysis of specific target molecules in defined tissue
compartments. 相似文献
983.
Guiseppi-Elie A 《Analytical and bioanalytical chemistry》2011,399(1):403-419
Following hemorrhage-causing injury, lactate levels rise and correlate with the severity of injury and are a surrogate of
oxygen debt. Posttraumatic injury also includes hyperglycemia, with continuously elevated glucose levels leading to extensive
tissue damage, septicemia, and multiple organ dysfunction syndrome. A temporary, implantable, integrated glucose and lactate
biosensor and communications biochip for physiological status monitoring during hemorrhage and for intensive care unit stays
has been developed. The dual responsive, amperometric biotransducer uses the microdisc electrode array format upon which were
separately immobilized glucose oxidase and lactate oxidase within biorecognition layers, 1.0–5.0 μm thick, of 3 mol% tetraethyleneglycol
diacrylate cross-linked p(HEMA-co-PEGMA-co-HMMA-co-SPA)-p(Py-co-PyBA) electroconductive hydrogels. The device was then coated with a bioactive hydrogel layer containing phosphoryl choline
and polyethylene glycol pendant moieties [p(HEMA-co-PEGMA-co-HMMA-co-MPC)] for indwelling biocompatibility. In vitro cell proliferation and viability studies confirmed both polymers to be non-cytotoxic;
however, PPy-based electroconductive hydrogels showed greater RMS 13 and PC12 proliferation compared to controls. The glucose
and lactate biotransducers exhibited linear dynamic ranges of 0.10–13.0 mM glucose and 1.0–7.0 mM and response times (t
95) of 50 and 35–40 s, respectively. Operational stability gave 80% of the initial biosensor response after 5 days of continuous
operation at 37 °C. Preliminary in vivo studies in a Sprague–Dawley hemorrhage model showed tissue lactate levels to rise
more rapidly than systematic lactate. The potential for an implantable biochip that supports telemetric reporting of intramuscular
lactate and glucose levels allows the refinement of resuscitation approaches for civilian and combat trauma victims. 相似文献
984.
Comparison and characterization of polysaccharides from natural and cultured Cordyceps on the basis of their chemical characteristics such as glycosidic linkages were performed for the first time using saccharide
mapping. The results showed that polysaccharides from most of the natural and cultured Cordyceps had similar responses to enzymatic digestion. These polysaccharides mainly contained (1→4)-β-D-glucosidic linkages, and (1→4)-α-glucosidic, (1→6)-α-glucosidic, 1,4-β-D-mannosidic, as well as (1→4)-α-D-galactosiduronic linkages also existed in some polysaccharides. Especially, natural and cultured Cordyceps polysaccharides could be discriminated on the basis of high performance liquid chromatography profiles of pectinase hydrolysates,
which is helpful to control the quality of polysaccharides from Cordyceps. 相似文献
985.
A multi-element analytical method based on inductively coupled plasma atomic emission spectrometry (ICP-AES) was developed
for trace elements in pharmaceutical tablets and cosmetics. Titanium was also included in the analytes since it is widely
used in pharmaceuticals. Critical ICP conditions, like RF incident power, argon gas flow rate and nebulizer sample uptake
flow rate were optimized. The most sensitive spectral line of each analyte was selected as optimum for further study. Detection
limits in the low μg g−1 range were obtained. Prior to chemical analysis, the samples were decomposed by acid digestion, using various mixtures of
HCl, HNO3 and HF. Yttrium was used as a suitable internal standard in order to correct for possible matrix effects. The method was
applied to the analysis of six different pharmaceutical products (anti-biotic, anti-inflammatory, anti-hypertensive) in the
form of tablets with film coating and also three cosmetic products like hair and face masks. 相似文献
986.
987.
This paper proposes to obtain homogeneous and stable blends of oligo(9,9-dioctylfluorene)-co-phenylene (OF), a conjugated oligomer with strong tendency of formation of excimers in the solid state, and nitrile rubber (NBR). This rubber protection reduces the formation of polymer excimers in the films. The fluorene oligomer was synthesized via Suzuki reaction and incorporated in the nitrile rubber. The films were formed by spin coating and casting techniques on the proportions of 1, 5, 10, 20 and 50 % (w/w) of OF in the nitrile rubber (NBR). The structural, optical and thermal properties of the films were evaluated with infrared, UV–Vis, fluorescence and thermogravimetry, respectively. The nitrile rubber proved to be essential for the preparation of homogeneous and stable films, since it was not possible to obtain films with only fluorene using the above-mentioned techniques. Furthermore, luminescent properties of OF are unchanged and the excimers formation in the solid state decrease suggesting the efficiency of nitrile rubber as the matrix for making films. 相似文献
988.
The inclusion complexes of a series of 4-arylidenamino-5-phenyl-4H-1, 2, 4-triazole-3-thiols have been prepared with β-cyclodextrin. The compounds and their inclusion complexes have been characterized by studying their physical and spectral properties. The thermodynamic stability constant and free energy of activation have been determined to know the stability of inclusion complexes and type of host-guest relation. Finally, absorption, excitation and emission spectra of the compounds (4-arylidenamino-5-phenyl-4H-1, 2, 4-triazole-3-thiols) and their inclusion complexes have been taken. It is found that inclusion complex formation brings about a drastic change in absorption and fluorescence characteristic (both excitation and emission spectra) of newly synthesized compounds. 相似文献
989.
Identification,characterization and evolution of non-local quasi-Lagrangian structures in turbulence
Yue Yang 《Acta Mechanica Sinica》2016,32(3):351-361
The recent progress on non-local Lagrangian and quasi-Lagrangian structures in turbulence is reviewed. The quasi-Lagrangian structures, e.g., vortex surfaces in vis-cous flow, gas-liquid interfaces in multi-phase flow, and flame fronts in premixed combustion, can show essential Lagrangian following properties, but they are able to have topological changes in the temporal evolution. In addition, they can represent or influence the turbulent flow field. The challenges for the investigation of the non-local structures include their identification, characterization, and evolution. The improving understanding of the quasi-Lagrangian struc-tures is expected to be helpful to elucidate crucial dynamics and develop structure-based predictive models in turbulence. 相似文献
990.
Chu Rainer Kwang-Hua 《Journal of Experimental and Theoretical Physics》2016,123(5):822-826
We illustrate the possible acceleration of cosmic rays passing through a kind of amplification channel (via diffusion modes of propagating plane-wave fronts) induced by a rotating system. Our analysis is mainly based on the quantum discrete kinetic model (considering a discrete Uehling-Uhlenbeck collision term), which has been used to study the propagation of plane (e.g., acoustic) waves in a system of rotating gases. 相似文献