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81.
Lippert AR Keshari KR Kurhanewicz J Chang CJ 《Journal of the American Chemical Society》2011,133(11):3776-3779
We report a new reaction-based approach for the detection of hydrogen peroxide (H(2)O(2)) using hyperpolarized (13)C magnetic resonance imaging ((13)C MRI) and the H(2)O(2)-mediated oxidation of α-ketoacids to carboxylic acids. (13)C-Benzoylformic acid reacts selectively with H(2)O(2) over other reactive oxygen species to generate (13)C-benzoic acid and can be hyperpolarized using dynamic nuclear polarization, providing a method for dual-frequency detection of H(2)O(2). Phantom images collected using frequency-specific imaging sequences demonstrate the efficacy of this responsive contrast agent to monitor H(2)O(2) at pre-clinical field strengths. The combination of reaction-based detection chemistry and hyperpolarized (13)C MRI provides a potentially powerful new methodology for non-invasive multi-analyte imaging in living systems. 相似文献
82.
Singh PK Kumbhakar M Pal H Nath S 《Chemical communications (Cambridge, England)》2011,47(24):6912-6914
The reactivity between two charged molecules and the activity of charged biomolecules are mainly governed by the principle of electrostatic interaction, i.e., like charges repel and opposite charges attract. In the present study it is shown that the principle of electrostatic interaction is violated in the nano-confined biomimetic environment. Thus a positively charged molecule shows more preference to a positively charged surface compared to a negatively charged surface. 相似文献
83.
Das P Mandal AK Kesharwani MK Suresh E Ganguly B Das A 《Chemical communications (Cambridge, England)》2011,47(26):7398-7400
A receptor with acidic methylene hydrogens is found to act as an efficient binding mode for F(-). This reagent could as well be used for selective and quantitative extraction of F(-) from the aqueous solution of NaF and sea water. 相似文献
84.
Manoj Yadav Wenquan Gong Allan J. Jacobson 《Journal of Solid State Electrochemistry》2011,15(2):293-301
Oxygen gas can be electrochemically separated from ambient air with very high purity and compressed by using a solid-electrolyte
ion-transport membrane. An electrolyte with high ionic conductivity such as gadolinium-doped ceria (CGO) and mixed conducting
electrodes are used to construct the electrochemical cell. To achieve high oxygen flux, the electrodes must exhibit very fast
electrode kinetics. Here, we report the performances of mixed conducting PrBaCo2O5 + x
and NdBaCo2O5 + x
electrodes in oxygen separation in a planar CGO electrolyte-supported cell. The properties of the electrode materials were
evaluated using potentiostatic and potentiodynamic measurements and alternating current impedance spectroscopy. The oxygen
flux was also measured using gas chromatography to confirm the absence of gas leaks. The electrodes demonstrated very low
polarization resistances as a result of very high cathodic and anodic reaction rates at temperatures of 600–800 °C. High oxygen
gas flow rates were observed on applying potentials up to 1 V with an almost linear relationship between the applied potential
and the molar flow rate of oxygen gas. 相似文献
85.
86.
Scale effects on strength of geomaterials, case study: Coal 总被引:1,自引:0,他引:1
Scale effects on the strength of coal are studied using a discrete element model. The key point of the model is its capability to discriminate between the “strictly sample size” effect and the “Discrete Fracture Network (DFN) density” effect on the mechanical response. Simulations of true triaxial compression tests are carried out to identify their respective roles. The possible bias due to the discretization size distribution of the discrete element model is investigated in detail by considering low-resolution configurations. The model is shown to be capable of quantitatively reproducing the dependency of the maximum strength on the size of the sample. This relationship mainly relies on the DFN density. For all given sizes, as long as the DFN density remains constant with a uniform distribution or if discontinuities are absent in the considered medium, the maximum strength of the material remains constant. 相似文献
87.
Effect of Second Order Chemical Reaction on
MHD Free Convective Radiating Flow over an
Impulsively Started Vertical Plate
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Bharat Keshari Swain 《Journal of Nonlinear Modeling and Analysis》2021,3(2):167-178
An attempt has been made to study laminar convective heat and mass transfer flow of an incompressible, viscous and electrically conducting fluid over an impulsively started vertical plate with conduction-radiation embedded in a porous medium in presence of transverse magnetic field. The influence of both second order chemical reaction and heat generation are taken into account. The governing coupled partial differential equations are solved by Crank-Nicolson method. The effects of important physical parameters on the velocity, temperature and concentration have been analyzed through graphs. The results of the present study agree well with the previous solutions. Applications of the present study are shown in material processing systems and different industries. The important findings of present study are: chemical reaction parameter acts as resistive force to reduce the velocity whereas heat source parameter enhances the velocity. 相似文献
88.
Manoj Kumar Chandra Mohan Sang Kyun Shim June Key Lee Nakwon Jang Naesung Lee Wael Z. Tawfik 《Molecules (Basel, Switzerland)》2021,26(13)
The far ultraviolet C (UVC) light sources based on carbon nanotube (CNT) field emitters as excitation sources have become promising light sources for sterilization, disinfection, and water purification. However, the low light extraction efficiency of UVC–CNT light sources still hinders the practical application of these structures. Herein, we report an optimized aluminum (Al) reflector to enhance the light extraction efficiency of UVC–CNT light sources. Optical analysis of UVC-CNT light sources covered by the Al reflectors with various thicknesses ranging from 30 to 150 nm was performed to realize the optimized reflector. The UVC-CNT light sources exhibit the highest light extraction efficiency when the Al reflector layer has an optimized thickness of 100 nm. For comparison, the cathodoluminescence (CL) spectra were recorded for UVC–CNT light sources with and without the optimized Al reflector. The measured light output power and the estimated power efficiency of the UVC–CNT light-source-tube with Al reflector were enhanced by about 27 times over the reference. This enhancement is mainly attributed to the outstanding reflection effect of the Al reflector. 相似文献
89.
G. Saravanan M. V. Suryanarayana Manoj J. Jadhav M. Ravikumar N. Someswararao P. V. R. Acharyulu 《Chromatographia》2007,66(5-6):435-438
This present work narrates the stress stability behavior and development of a liquid chromatographic method for the quantitative
determination of anastrozole. Anastrozole is appropriately used when using substantial amounts of aromatizing steroids, or
when one is prone to gynecomastia and using moderate amounts of such steroids. A chromatographic separation was achieved on
a Hichrom RPB18 (250 × 4.6 mm, 5 μ) column using water and mixture of acetonitrile and methanol (1:1 ratio) as mobile phase.
Forced degradation studies were performed on bulk samples of anastrozole using acid, base, hydrogen peroxide, heat and UV
light. Degradation of the drug substance was observed in base hydrolysis. Degradation product formed under base hydrolysis
was found to be Imp-C. The sample solution and mobile phase were found to be stable up to 48 h. The developed method was validated
with respect to linearity, accuracy, precision, robustness and forced degradation studies prove the stability indicating power
of the method. 相似文献
90.
CaS phosphor activated with Dy ions is prepared by the solid-state diffusion method. The phosphor is characterized by x-ray powder diffraction, thermogravimetric analysis and photoiuminescence. Defect centres formed in CaS:Dy are studied using the technique of electron spin resonance. The thermoluminescence glow curve shows peaks at around 117℃ and 345℃. Irradiated CaS:Dy exhibits ESR lines due to defect centres. The thermal annealing behaviour of one of the defect centres appears to correlate with the TL peaks at 117℃ and 345℃. This centre is characterized by an isotropic g-value of 2.0035 and is assigned to an F^+ centre. 相似文献