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201.
Amna S. A. Zidan Asma I. El-Said 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):1293-1305
The complexes [Ni{(RO)2PS2}2Tsc], [Ni{(RO)2PS2}2ApTsc], and [Ni{(RO)2PS2}FurTsc.2H2O] where R = methyl (Me), ethyl (Et) or propyl (Prop); Tsc = thiosemicarbazide, ApTsc = 2-acetylpyridine-thiosemicarbazone, and FurTsc = furfuraldhydethiosemicarbazone have been synthesized and characterized by elemental analysis, conductance measurements, and spectral studies (IR, UV-Vis, and mass). Thermal studies of the complexes have been carried out using TG and DTG techniques. An octahedral structure has been proposed for all types of the complexes. A representative types of the complexes are tested against various pathogenic bacteria and fungi. The [Ni{(EtO)2PS2}2ApTsc] shows a high degree of activity against bacteria and fungi; this may be attributed to the pyridyl ring of the 2-acetylpyridinethiosemicarbazone ligand. 相似文献
202.
Asma Farhat Christian Ginies Mehrez Romdhane Farid Chemat 《Journal of chromatography. A》2009,1216(26):5077-5085
Microwave steam diffusion (MSD) was developed as a cleaner and new process design and operation for isolation of essentials oils and was compared to conventional steam diffusion (SD). The essential oils extracted by MSD for 3 min were quantitatively (yield) and qualitatively (aromatic profile) similar to those obtained by conventional steam diffusion for 20 min. In addition, an optimal operating steam flow rate of 25 g min−1 and microwave power 200 W were found to ensure complete extraction yield with reduced extraction time. To confirm the efficiency of this process a mathematical model was proposed to describe the mass transfer of essential oil from lavender. Solid-steam mass transfer coefficients obtained by MSD were six times higher than obtained by SD. Scanning electronic microscopy was used to confirm the extraction mechanism of the essential oil present in the glandular trichomes of the flowers from lavender outer surface. MSD was better than SD in terms of energy saving, cleanliness and reduced waste water. 相似文献
203.
The binding interaction of captopril (CPL) with biologically active metal ions Mg2+, Ca2+, Mn2+, Co2+, Ni2+, Cu2+ and Zn2+ was investigated in an aqueous acidic medium by fluorescence spectroscopy. The experimental results showed that the metal ions quenched the intrinsic fluorescence of CPL by forming CPL‐metal complexes. It was found that static quenching was the main reason for the fluorescence quenching. The quenching constant in the case of Cu2+ was highest among all quenchers, perhaps due to its high nuclear charge and small size. Quenching of CPL by metal ions follows the order Cu2+>Ni2+>Co2+>Ca2+>Zn2+>Mn2+>Mg2+. The quenching constant Ksv, bimolecular quenching constant Kq, binding constant K and the binding sites "n" were determined together with their thermodynamic parameters at 27 and 37°C. The positive entropy change indicated the gain in configurational entropy as a result of chelation. The process of interaction was spontaneous and mainly ΔS‐driven. 相似文献
204.
Asma Tufail Shah Adnan Mujahid Muhammad Umar Farooq Waqar Ahmad Baoshan Li Muhammad Irfan Muhammad Abdul Qadir 《Journal of Sol-Gel Science and Technology》2012,63(1):194-199
The nanoparticles of monovacant lacunary keggin-type polyoxometalate (C19H42N)4H3(PW11O39) has been successfully synthesized by Micelle Directed Method using hexadecyltrimthyl ammonium bromide (CTAB) as a template. Non-ionic copolymer Pluronic F127 was used as a capping agent that helps in formation of nanoparticles by preventing the aggregation during the coating of H3(PW11O39)4- onto the counter ion (C19H42N)+. The synthesized material was characterized by Scanning electron microscope (SEM), TGA, DSC and FT-IR techniques. SEM images indicated that (C19H42N)4H3(PW11O39) nanoparticles possess spherical structure. FTIR results revealed that the structural integrity of monovacant lacunary keggin-type polyoxometalates (POM) was not affected when reducing the size. TGA–DSC results showed that the material was thermally stable (with 37 % weight loss) and POM encapsulates CTAB. The efficiency of synthesized material was checked by applying it as a catalyst for the oxidation of toxic mordant yellow dye i.e., potentially hazardous and non-biodegradable azo dye. The (C19H42N)4H3(PW11O39) nanoparticles gave 96 % dye degradation in 60 min at 60 °C temperature. Moreover, on recycling POM nanoparticles demonstrate 92 % oxidative degradation of mordant yellow dye. 相似文献
205.
A new green TLC has been used for identifying and monitoring the migration behavior of amino acids through silica and kieselguhr static flat bed in contact of n-butyl alcohol, ethyl acetate or ethylene glycol and their mixtures. From the point of view of chromatographic performance, a mixture of n-butyl alcohol-70% aqueous ethylene glycol-ethyl acetate ratio 5:3:2 by volume proves to be more efficient than the individual components for separation of amino acids from their binary, ternary and quaternary mixtures and the chromatographic parameters like ΔR(F) , separation factor (α) and resolution (R(S) ) for the separation were calculated. Effect of the presence of foreign substances such as metal cations, anions, vitamins and pesticides as impurities in the sample on the separation was also examined. Effect of substitution of butanol by various alcohols has been examined to assess the impact of hydrophobicity of alcohols on the separation of amino acids. The limits of detection for tyrosine, tryptophan, alanine, isoleucine, methionine and serine were found to be 0.10?μg/spot, whereas for lysine it is 0.05?μg/spot. Application of the selected TLC system for the identification and separation of amino acids present in drugs/pharmaceuticals has been performed. 相似文献
206.
ABSTRACTThis contribution deals with the study of the almost sure exponential stability of large-scale stochastic systems with multiplicative noises. Under a Lipschitz-like assumption, it is proven that this stability is guaranteed if each “diagonal” subsystem is almost surely exponentially stable. 相似文献
207.
A generalized version for a qubit based two-way quantum key distribution scheme was first proposed in the paper [Phys. Lett. A 358 (2006) 85] capitalizing on the six quantum states derived from three mutually unbiased bases. While boasting of a higher level of security, the protocol was not designed for ease of practical implementation. In this work, we propose modifications to the protocol, resulting not only in improved security but also in a more efficient and practical setup. We provide comparisons for calculated secure key rates for the protocols in noisy and lossy channels. 相似文献
208.
For X, Y ∈ Mn,m it is said that X is gut-majorized by Y, and we write X ?gutY, if there exists an n-by-n upper triangular g-row stochastic matrix R such that X = RY. Define the relation ~gut as follows. X ~gutY if X is gut-majorized by Y and Y is gut-majorized by X. The (strong) linear preservers of ?gut on ?n and strong linear preservers of this relation on Mn,m have been characterized before. This paper characterizes all (strong) linear preservers and strong linear preservers of ~gut on ?n and Mn,m. 相似文献
209.
Choudhary MI Begum A Abbaskhan A Ajaz A Shafique-ur-Rehman Atta-ur-Rahman 《Chemical & pharmaceutical bulletin》2005,53(11):1469-1471
A phytochemical investigation on the aerial parts of Lindelofia stylosa has resulted in the isolation of seven phenyl propanoids. This includes three analogs of lithospermic acid, along with rosmarinic acid and its ester derivatives. Compound 1 was identified as a new natural product. These compounds were studied for their antioxidant properties. 相似文献
210.
Maliha Asma Amin Badshah Saqib Ali Manzar Sohail Mohammed Fettouhi Saeed Ahmad Abdul Malik 《Transition Metal Chemistry》2006,31(4):556-559
A number of palladium(II) complexes with Ph3P and aromatic amines as ligands having the general formula [(Ph3P)Pd(Ph3P)(NH2R)Cl2] {where R = Ph (1), m-ClC6H4 (2), p-ClC6H5 (3)} and [Pd(CH3NHPh)Cl2] (4), have been synthesized and characterized by elemental analysis, IR, 1H and 13C NMR. The X-ray crystal structure of [(Ph3P)Pd(m-ClC6H4NH2)Cl2] · CH2 Cl2 (2) shows a distorted square planar environment around the Pd(II) ion with the P–Pd–N and Cl(1)–Pd–Cl(2) bond angles of 174.88(5)°
and 176.77(2)° respectively. The complexes were screened for enzyme inhibition activity against β-glucuronidase and found to be active. 相似文献