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91.
In this paper we presented a method, which will allow multiple parameter control of the 3-dB bandwidth, center notch wavelength and attenuation level in a fiber-based acousto-optic tunable filter (AOTF). The method basically involves the variation of the interaction length, RF frequency and RF power on a single-fiber device to achieve multiple parameters tuning of the optical filter. The acousto-optic (AO) interaction inside a single-mode fiber (SMF) was studied theoretically and experimentally. 相似文献
92.
Sung Joong Lee Semin Park Jin Young Choi Jae‐Han Shim Eun‐Ho Shin Jeong‐Heui Choi Soo Taek Kim A. M. Abd El‐Aty Jong Sung Jin Dong Won Bae Sung Chul Shin 《Biomedical chromatography : BMC》2009,23(7):719-731
It would be preferable for pesticide residues substituted by hydrolyzable functionality to be analyzed after cooking because their structures are apt to degrade during boiling and/or heating. A liquid chromatography–tandem mass spectrometry (LC‐MS/MS) method for the quantitative determination of 44 pesticide residues with hydrolyzable functional group in five typical vegetable widely consumed in Republic of Korea is described. The sample clean‐up was carried out according to the method of Food Code No. 83 established by the Korea Food and Drug Administration (KFDA). Zorbox XDB‐C18 column was selected for the analysis because of the best peak separation. The LC mobile phase consisted of water and 5 mm methanolic ammonium formate, which resulted in a peak shape with good symmetry at each run. Tandem mass spectroscopic (MS/MS) experiments were performed in ESI positive mode and the multiple reaction monitoring modes. A conventional matrix effect was modified to more comprehensive form 100γij (%). A high matrix effect (30%) was detected for the seven polar pesticides, namely thiamethoxam, clothianidin, acetamiprid, aldicarb, thiacloprid, pirimicarb and methabenzthiazuron. The limits of detection were in the range of 0.1–8.1 µg/kg, indicating a good sensitivity. Most of the recoveries ranged from 70 to 131% with RSDs ≤ 20%. The current method allowed rapid quantitation and identification of low pesticide levels in the cooked vegetable samples. Of the screened pesticide residues, only fluquinconazole and dimethomorph below the maximum residue levels established by the KFDA were detected in onion and cucumber samples. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
93.
94.
The synthesis of several new polyfunctionally substituted fused pyrazoles via reaction of 5‐amino‐3‐methylthio‐1H‐pyrazole‐4‐carboxylate ( 2 ) with different reagents is described. 相似文献
95.
The treatment of a Λ-type three-level atom interacting with a single mode field in a cavity, explicitly taking the existence of forms of nonlinearities of both the field and the intensity-dependent atom-field coupling into account. Analytical expressions of the emission and absorption spectra are presented using the dressed states of the system. The characteristics of the emission and absorption spectra for binomial state and squeezedcoherent state inputs are exhibited. The effects of the mean number of photons, the detuning, and the nonlinearities on the spectra are investigated. It is shown that the features of the fluorescence and absorption spectra are influenced significantly by the kinds of nonlinearities. 相似文献
96.
A. A. El-Shafei A. M. Abd Elhafeez H. A. Mostafa 《Journal of Solid State Electrochemistry》2010,14(2):185-190
Impregnated Pd–zeolite graphite (PdZG) electrodes have been tested for ethanol oxidation in 0.5 M NaOH. The results obtained
have been compared with that of Pd electrode. Cyclic voltammetric and chronoamperometric measurements indicated the activity
of PdZG electrode toward ethanol oxidation and poisoning tolerance. The influence of zeolite loading as well as impregnation
time in Pd2+ solution has been examined. Scan rate effect and ethanol concentration dependency indicated that ethanol oxidation at PdZG
electrode was governed by diffusion control. 相似文献
97.
Abd Elmoneim O. Elkhalifa Eyad Al-Shammari Mohd Adnan Jerold C. Alcantara Khalid Mehmood Nagat Elzein Eltoum Amir Mahgoub Awadelkareem Mushtaq Ahmad Khan Syed Amir Ashraf 《Molecules (Basel, Switzerland)》2021,26(12)
Abelmoschus esculentus (Okra) is an important vegetable crop, widely cultivated around the world due to its high nutritional significance along with several health benefits. Different parts of okra including its mucilage have been currently studied for its role in various therapeutic applications. Therefore, we aimed to develop and characterize the okra mucilage biopolymer (OMB) for its physicochemical properties as well as to evaluate its in vitro antidiabetic activity. The characterization of OMB using Fourier-transform infrared spectroscopy (FT-IR) revealed that okra mucilage containing polysaccharides lies in the bandwidth of 3279 and 1030 cm−1, which constitutes the fingerprint region of the spectrum. In addition, physicochemical parameters such as percentage yield, percentage solubility, and swelling index were found to be 2.66%, 96.9%, and 5, respectively. A mineral analysis of newly developed biopolymers showed a substantial amount of calcium (412 mg/100 g), potassium (418 mg/100 g), phosphorus (60 mg/100 g), iron (47 mg/100 g), zinc (16 mg/100 g), and sodium (9 mg/100 g). The significant antidiabetic potential of OMB was demonstrated using α-amylase and α-glucosidase enzyme inhibitory assay. Further investigations are required to explore the newly developed biopolymer for its toxicity, efficacy, and its possible utilization in food, nutraceutical, as well as pharmaceutical industries. 相似文献
98.
Magdy M. Gineinah Abd El-Kader M. Ismaiel Mohamed M. El-Kerdawy Richard A. Glennon 《Journal of heterocyclic chemistry》1990,27(3):723-726
Because of the close structural similarity between triazoloquinazolines and certain 5-membered ring mesoionic heterocycles, all of which possess antiinflammatory activity, we prepared several examples of the novel mesoionic 1,2,4-triazolo[4,3-c]quinazoline ring system for their therapeutic potential. These compounds can be prepared by the cyclization of the appropriately substituted 4-hydrazinoquinazolines with phosgene. When the mesoionic product was unsubstituted at the 5-position (i.e., quinazoline 2-position), it could only be isolated as its hydrochloride salt and not as its unstable free base. None of the mesoionic products were sufficiently stable in solution to allow for evaluation of their antiinflammatory activity. 相似文献
99.
Mohamed M. Ibrahim Abd El-Motaleb. M. Ramadan 《Journal of inclusion phenomena and macrocyclic chemistry》2010,68(3-4):287-296
Two new artificial peptides with histidine side chains, namely N-methyl N,N′-bis(Im-bzl-l-histidylmethylestermethyl)amine L1 and N,N′,N″,N?-tetrakis(Im-bzl-l-histidylmethyl-estermethyl)ethylene diamine L2 have been synthesized and were shown to form stable zinc complexes [L1Zn(H2O)2](ClO4)2 1 and [L2Zn2(H2O)3](ClO4)4 2, respectively. Solution studies (pH–1NMR titrations) of the ligand L2 in the presence of zinc ions were also reported. The catalytic activity of zinc complex species 1 and 2 as structural phosphotriestrase models were tested on the hydrolysis/detoxification of p-nitrohenl diphenylphosphate (p-NPDPP). From the correlation between the pH-rate profiles and the species distribution curves, the catalytically active species could be identified. On the basis of R-dependence as well as the rate acceleration of each complex, the possibility of cooperative action of zincs in dinuclear zinc complex is debated. 相似文献
100.
Jiun‐Yang Chang Mohamed H. Abd El‐Razek Yu‐Hui Chen Yuan‐Bin Cheng Shun‐Ying Chen Ching‐Te Chien Yao‐Haur Kuo Ya‐Ching Shen 《Helvetica chimica acta》2010,93(1):123-132
A phytochemical investigation of the MeOH extract of Illicium arborescens yielded the two new phytoquinoid epimers, 2,3‐didehydro‐5‐O‐methyl‐11‐epiillifunone E ( 1 ) and 2,3‐didehydro‐5‐O‐methylillifunone E ( 2 ), as well as five new sesquiterpene lactones (8,9‐secoprezizaane‐type sesquiterpenes). Two of them, i.e., 3 and 4 , were minwanensin‐type sesquiterpenes, the other two, i.e., 5 and 6 , had the anisatin‐type (or floridanolide type) skeleton, and the fifth, i.e., 7 , was a dunnianin‐type sesquiterpene. Their structures were established by analyses of 1D‐ and 2D‐NMR, HR‐MS, and chemical evidence. The in vitro cytotoxic activity of compounds 1 – 7 was tested against four human tumor cell lines, including HeLa (cervical epitheloid), WiDr (colon), Daoy (medulloblastoma), and Hep2 (liver carcinoma) human‐tumor cells. 相似文献