排序方式: 共有14条查询结果,搜索用时 15 毫秒
1.
Mahamood K. Nadira Divya P. V. Vineethkumar V. Prakash V. 《Journal of Radioanalytical and Nuclear Chemistry》2020,324(3):949-961
Journal of Radioanalytical and Nuclear Chemistry - The activity concentration of natural radionucides such as 40K, 226Ra and 232Th and radon surface and mass exhalation rates of the soil were... 相似文献
2.
Nadira Boukli-Hacene 《Nonlinear Analysis: Theory, Methods & Applications》2009,71(9):3612-3621
In this work, we give sufficient conditions for the existence and uniqueness of a weighted pseudo almost periodic solution for some partial functional differential equations. To illustrate our main result, we study the existence of a weighted pseudo almost periodic solution for some diffusion equation with delay. 相似文献
3.
Meryem Saidi Phuoc Hoang Ho Pankaj Yadav Fabrice Salles Clarence Charnay Luc Girard Leila Boukli-Hacene Philippe Trens 《Molecules (Basel, Switzerland)》2021,26(24)
This paper reports on the comparison of three zirconium-based metal organic frameworks (MOFs) for the capture of carbon dioxide and ethanol vapour at ambient conditions. In terms of efficiency, two parameters were evaluated by experimental and modeling means, namely the nature of the ligands and the size of the cavities. We demonstrated that amongst three Zr-based MOFs, MIP-202 has the highest affinity for CO2 (−50 kJ·mol−1 at low coverage against around −20 kJ·mol−1 for MOF-801 and Muc Zr MOF), which could be related to the presence of amino functions borne by its aspartic acid ligands as well as the presence of extra-framework anions. On the other side, regardless of the ligand size, these three materials were able to adsorb similar amounts of carbon dioxide at 1 atm (between 2 and 2.5 µmol·m−2 at 298 K). These experimental findings were consistent with modeling studies, despite chemisorption effects, which could not be taken into consideration by classical Monte Carlo simulations. Ethanol adsorption confirmed these results, higher enthalpies being found at low coverage for the three materials because of stronger van der Waals interactions. Two distinct sorption processes were proposed in the case of MIP-202 to explain the shape of the enthalpic profiles. 相似文献
4.
Exponentially growing cells of the PtK-2 line (ATCC No. CCL56, from the marsupial Potorous tridactylus) require protein and RNA synthesis in a limited period following UV-radiation damage for optimal recovery as colony formers [Overberg et al. (1988) Mutat. Res. 194, 83-92]. Overall behavior suggests the operation of damage-induced recovery processes. The capacity of confluent cell monolayers for infection with unirradiated herpes simplex virus 1 (HSV-1) is sharply reduced by UV-irradiation. We have followed capacity changes in exponentially growing cells after irradiation and varying amounts of photoreactivation by means of an infectious center assay. These changes closely parallel changes of colony formation. Spontaneous recovery of capacity in the dark occurs over approximately the same time period that the UV sensitivity of colony formation depends on macromolecular synthesis. The effect of photoreactivation is complementary rather than additive to this recovery, suggesting that the dark recovery in this period concerns pyrimidine dimers in cell DNA. 相似文献
5.
Nadira Ibri?imovi? Mirza Ibri?imovi? Margit Barth Ulrich Bohrn 《Monatshefte für Chemie / Chemical Monthly》2010,205(2):125-130
Abstract
Spoilage of products can mainly be attributed to microorganisms which “live on the product”, i.e. which are able to utilize and/or metabolize components and/or molecules of the product. The objective of this work was to develop and optimize sensor prototypes indicating the quality of a product “in real time”, i.e. at the time the consumer is looking at the product. The design of the presented sensors relates to optical phenomena, for example anomalous absorption and remission of light. The crucial point of the sensor prototypes is a layer sensitive to the analyte, a polymer degradable by enzymes produced by the respective microorganisms. After incubation of the sensor setup with contaminated products, the lytic enzymes released from decaying cell material change the thickness of the polymer layer and generate a colour change visible by the naked eye. Production of the sensor prototypes is very simple and inexpensive and they might be successfully integrated into product packaging. 相似文献6.
7.
Nadira Moufid Philippe Renaud Carla Hassler Bernd Giese 《Helvetica chimica acta》1995,78(4):1006-1012
The stereoselectivity in reactions of 2-oxy-substituted radicals of type B was investigated. As expected, minimization of allylic 1,3-strain was the major controlling factor. Under standard conditions, only a modest level of stereoselectivity was observed. E.g., deuteration of the benzylated radical (R1 = benzyl) gave diastereoisomer ratios ≤ 2:1. Use of a bulky protective group on the O-atom (R1 = (t-Bu)Ph2Si) enhanced slightly the selectivity (ratio 4.1:1). However, a dramatic increase of the stereoselectivity (ratio 13:1) was obtained, when the reaction was performed with the free alcohol after treatment with bulky methylaluminium bis(phenoxide) derivatives (methyl-aluminium bis[2,6-di(tert-butyl)-4-methylphenoxide] (MAD) and methylaluminium bis(2,6-diphenylphenoxide) (MAPH)). 相似文献
8.
We successfully determined the molecular structure of peroxycitric acid (PCA) coexisting in the aqueous equilibrium mixture with citric acid (CA; 1,2,3-tricarboxylic-2-hydroxy propane) and hydrogen peroxide (H2O2) by a combined use of reversed-phase HPLC (RP-HPLC), potentiometric, hydrodynamic chronocoulometric (HCC) and electrospray ionization mass spectroscopic (ESI-MS) methods. Firstly, the RP-HPLC was employed to separate CA, PCA and H2O2 coexisting in the equilibrium mixture and the concentration of CA consumed (ΔCCA) in the formation of PCA that was evidenced to be fairly stable during the RP-HPLC measurement was quantitatively measured based on the standard calibration curve of CA. Secondly, the total oxidant concentration (COx) corresponding to peroxycarboxylic (–COOOH) group in PCA in the equilibrium mixture was determined using potentiometric measurement. The ratio of COx/ΔCCA was found to be 1.07, which indicates that only one –COOH group in CA molecule is oxidized to the corresponding –COOOH group in PCA molecule. Thirdly, using the HCC technique the diffusion coefficient of PCA, which could be electroreduced at a more positive potential by 1.0 V than the coexisting H2O2, was independently measured as 0.3 × 10−5 cm2 s−1 and at the same time, by considering ΔCCA as the concentration of PCA, the number of electrons (n) required for the reduction of PCA was determined to be 2. The result obtained from RP-HPLC and HCC, i.e., n = 2 which is equivalent to one –COOOH group in PCA, is in agreement with that obtained from the combination of RP-HPLC and potentiometric measurements. Finally, the structure of PCA was proposed to contain one –COOOH group with a molecular mass of 208 confirmed by negative ion ESI-MS method. A probable molecular structure of PCA was discussed. 相似文献
9.
Grace B. Borowitz Irving J. Borowitz Yizhe Wang Dingqiao Yang Richard Toupence Nadira A. Persaud 《Journal of inclusion phenomena and macrocyclic chemistry》2000,38(1-4):207-219
The synthesis of N-(2-hydroxy-1-phenoxyacetyl)prolylproline 2 from 2-acetoxyphen-oxyacetic acid is described. A firstsynthesis led toN-(2-acetoxy-1-phenoxyacetyl)prolylproline methylester 8b that fragmented upon attempted esterhydrolysis with 1N NaOH. A second synthesis gave thecorresponding benzyl ester 13, which wasconverted to 2 by deacylation of the phenolicacetoxy group with pyrrolidine followed byhydrogenolysis of the ester. Cation binding by 2 in methanol and related molecular mechanics (MM)geometric optimizations are discussed. 相似文献
10.
Nadira Ibrišimović Margit Barth Ulrich Bohrn Mirza Ibrišimović Fritz Pittner 《Monatshefte für Chemie / Chemical Monthly》2009,140(8):941-945
Abstract Conventional tests currently in use for the detection and identification of food-borne pathogens and also of microbial food
deterioration are time-consuming as they are based on conventional culturing techniques or monitoring environmental conditions
like the increase of temperature or change in pH. These parameters do not reflect the real quality of the meat to be tested.
The aim of our approach was to create a simple and cheap sensor providing reasonable sensitivity and selectivity to indicate
the bacterial infection in real-time monitoring combined with a memory effect that cannot easily be corrupted. Thus, an optical
thin film sensor chip was developed able to detect bacterial decay of food through a specific colour change. The design of
the sensor relates to the phenomenon of “anomalous absorption”, which can best be described as a thin film enhanced absorption.
A metal nanoparticle layer positioned at a well-defined distance to a smooth metal surface shows that the minimum of spectral
reflectivity strongly depends on the thickness of the distance layer. This setup represents a special kind of reflection interference
filter. In such a sensor setup a biomimetic polymer is integrated, which is degradable by lytic enzymes excreted by microorganisms
in food decay. Meat deterioration under controlled conditions is correlated to the amount of enzymes secreted by microorganisms
and the bacterial count. Thus, after incubation of the sensor setup with standard meat preparations, the enzymes released
from decaying cell material change the thickness of the polymer layer and generate an easily visible colour change. This setup
would be useful for integration into meat packaging.
Graphical Abstract
M. Barth, U. Bohrn and M. Ibrišimović contributed equally to this work. 相似文献