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61.
We consider the discrete time unitary dynamics given by a quantum walk on ${\mathbb {Z}^d}$ performed by a particle with internal degree of freedom, called coin state, according to the following iterated rule: a unitary update of the coin state takes place, followed by a shift on the lattice, conditioned on the coin state of the particle. We study the large time behavior of the quantum mechanical probability distribution of the position observable in ${\mathbb {Z}^d}$ for random updates of the coin states of the following form. The random sequences of unitary updates are given by a site-dependent function of a Markov chain in time, with the following properties: on each site, they share the same stationary Markovian distribution and, for each fixed time, they form a deterministic periodic pattern on the lattice. We prove a Feynman–Kac formula to express the characteristic function of the averaged distribution over the randomness at time n in terms of the nth power of an operator M. By analyzing the spectrum of M, we show that this distribution possesses a drift proportional to the time and its centered counterpart displays a diffusive behavior with a diffusion matrix we compute. Moderate and large deviation principles are also proven to hold for the averaged distribution and the limit of the suitably rescaled corresponding characteristic function is shown to satisfy a diffusion equation. An example of random updates for which the analysis of the distribution can be performed without averaging is worked out. The random distribution displays a deterministic drift proportional to time and its centered counterpart gives rise to a random diffusion matrix, the law of which we compute. We complete the picture by presenting an uncorrelated example. 相似文献
62.
Ragaa A. Hamouda Mervat H. Hussein Noura El-Ahmady El-Naggar Mohammed A. Karim-Eldeen Khalid H. Alamer Muneera A. Saleh Luluah M. Al Masoudi Eman M. Sharaf Reham M. Abd El-Azeem 《Molecules (Basel, Switzerland)》2022,27(4)
Seaweeds can play a vital role in plant growth promotion. Two concentrations (5 and 10 mg/mL) of soluble polysaccharides extracted from the green macroalgae Ulva fasciata and Ulva lactuca were tested on Zea mays L. The carbohydrate and protein contents, and antioxidant activities (phenols, ascorbic, peroxidase, and catalase) were measured, as well as the protein banding patterns. The soluble polysaccharides at 5 mg/mL had the greatest effect on the base of all of the parameters. The highest effects of soluble polysaccharides on the Zea mays were 38.453, 96.76, 4, 835, 1.658, 7.462, and 38615.19, mg/mL for carbohydrates, proteins, phenol, µg ascorbic/mL, mg peroxidase/g dry tissue, and units/g tissue of catalase, respectively. The total number of protein bands (as determined by SDS PAGE) was not changed, but the density of the bands was correlated to the treatments. The highest band density and promoting effect were correlated to 5 mg/mL soluble polysaccharide treatments extracted from Ulva fasciata in Zea mays, which can be used as a biofertilizer. 相似文献
63.
New Ni(II), Pd(II) and Pt(II) complexes coordinated to azo pyrazolone ligand with a potent anti‐tumor activity: Synthesis,characterization, DFT and DNA cleavage studies 下载免费PDF全文
Eman A. Bakr Gad B. Al‐Hefnawy Mohamed K. Awad Hossam H. Abd‐Elatty Mohamed S. Youssef 《应用有机金属化学》2018,32(2)
The absolute necessity to fight some class of tumor is perceived as serious health concerns, so the discovery and development of effective anticancer agents are urgently needed. (E)‐4‐((2‐hydroxyphenyl)diazenyl)‐3‐phenyl‐1H‐pyrazol‐5(4H)‐one, HL, and its Ni(II), Pd(II) and Pt(II) complexes were synthesized and the biological activity was evaluated for antitumor, antioxidant and antimicrobial activity as well as DNA cleavage. Their structures were assigned depending on the elemental analysis, conductivity, magnetic moment, spectral measurements (IR, 1HNMR, mass and UV–Vis) and thermal analysis. 3D molecular modeling using DFT method confirmed that the geometrical structures agree well with the suggested experimental ones. The antitumor activity was evaluated against four different cell lines using MTT assay. The ligand HL showed a potent cytotoxic activity compared to 5‐fluorouracil as a reference drug. For metal complexes, the order of activity was: Pd(II) > Ni(II) > Pt(II). A remarkable antioxidant activity for the ligand HL was recorded. It was higher than that of the metal complexes. Results of antimicrobial experiments revealed that all compounds were moderate to highly active against selected bacterial strains but inactive as antifungal except Pd(II) which showed a moderate antifungal activity. Gel electrophoresis showed insignificant nucleases activity for the ligand or its metal complexes even in the presence of H2O2 providing protection of DNA from damage. The antitumor activity of our compounds may be not due to DNA cleavage but may be referred to a mechanism similar to that of 5‐fluorouracil which interfere with DNA replication. The present work suggests the use of this ligand in the design and development of new anticancer drugs. 相似文献
64.
M. A. Moharram Samira M. Rabie Aisha Y. Daghistani 《International Journal of Infrared and Millimeter Waves》1992,13(9):1433-1447
Infrared spectroscopy was applied for the investigation of the combined effects of -irradiation and heat on polyvinyl alcohol (PVA). The samples were exposed in an atmosphere of air at room temperature to doses ranging form 0.5 to 15 M rads. The obtained results revealed that exposure to -irradiation produces no considerable changes in the IR spectra of PVA apart from very slight changes in the intensities of the absorption bands. The crystallinity of the irradiated samples was determined by following the induced changes in the absorbances of the crystalline bands.The IR spectra of PVA samples heated at 180°C exhibited two absorption bands at 1580 and 1710 cm–1 due to carbonyl groups. Alken double bonds and possibly also carboxyl groups.IR spectroscopy was also used for the examination of the effect of time of heating in air or in vacuum and also the effect of quenching of the degree of crystallinity of -irradiated PVA. Careful examination of the IR spectra led to the conclusion that the temperature induced changes depend on time of heating, rate of cooling and -dosage used. The highest crystallinity was obtained by heating in vacuum at 140°C and quenching at –40°C. 相似文献
65.
Divya Ganesan Eman Al-Sayed Abhishek Albert Eldho Paul Abdel Nasser B. Singab 《Natural product research》2018,32(11):1274-1280
Phytochemicals serve as potential therapeutic agents for the prevention and treatment of diseases. In this study, we elucidate the renoprotective activity of compounds isolated from Eucalyptus globulus and Melaleuca styphelioides extracts in glucose- and oxalate-challenged NRK-49F cell model. The antioxidant potential of isolated compounds was evaluated based on their effect on antioxidant enzyme activities and lipid peroxidation levels. The results demonstrated that exposure of NRK-49F cells to glucose and oxalate stress augmented cell damage and attenuated antioxidant enzyme activities. The phytochemicals 2,2,8-trimethyl-6-formyl-chrom-3-ene-7-O-β-D-glucopyranoside, Cornusiin B and tellimagrandin I treatment restored antioxidant enzyme activity, significantly lowered lipid peroxidation levels and effectively protected cells from glucose and oxalate stress equivalent to the known antioxidant, N-acetyl cysteine. Pterocarinin A significantly reversed cellular damage owing to glucose stress. In conclusion, the compounds isolated from E. globulus and M. styphelioides showed potential cytoprotective and anti-oxidative property against glucose- and oxalate-induced oxidative stress in NRK-49F cells. 相似文献
66.
L. V. Batog V. Yu. Rozhkov L. S. Konstantinova V. E. Eman M. O. Dekaprilevich Yu. T. Struchkov S. E. Semenov O. V. Lebedev L. I. Khmel'nitskii 《Russian Chemical Bulletin》1996,45(5):1189-1193
The oxidative cyclocondensation of 3,4-diaminofurazan and 4,4-diamino-3,3-azofurazan with dibromoisocyanurate afforded macrocyclec polydiazenofurazans. The reaction can be directed towards the formation of both the four-membered cycle alone or the three-, six-, and eight-membered macrocycles.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1250–1254, May, 1996.Deceased in 1995. 相似文献
67.
Bertelli M El-Bastawissy E Knaggs MH Barrett MP Hanau S Gilbert IH 《Journal of computer-aided molecular design》2001,15(5):465-475
A number of triphenylmethane derivatives have been screened against 6-phosphogluconate dehydrogenase from Trypanosoma brucei and sheep liver. Some of these compounds show good inhibition of the enzymes and also selectivity towards the parasite enzyme. Modelling was undertaken to dock the compounds into the active sites of both enzymes. Using a combination of DOCK 3.5 and FLEXIDOCK a correlation was obtained between docking score and both activity for the enzymes and selectivity. Visualisation of the docked structures of the inhibitors in the active sites of the enzymes yielded a possible explanation of the selectivity for the parasite enzyme. 相似文献
68.
Adel A.-H. Abdel-Rahman Ahmed E.-S. Abdel-Megied Mohamed A. M. Hawata Eman R. Kasem Mohamed T. Shabaan 《Monatshefte für Chemie / Chemical Monthly》2007,16(6):889-897
Chalcones were synthesized by a base catalyzed Claisen-Schmidt condensation reaction. Bromination of chalcones afforded the dibromo derivatives. Monobromo derivatives could be obtained
by treating the corresponding dibromochalcones with dry benzene in the presence of triethylamine. Pyrazole derivatives were
obtained by refluxing of dibromochalcones with phenylhydrazine or 2,4-dinitrophenylhydrazine in dry pyridine. Chalcones were
treated with hydrazine hydrate or phenyl hydrazine in ethanol to afford Δ
2-pyrazolines and N-phenyl-Δ
2-pyrazolines. Condensation of chalcones with hydroxylamine hydrochloride or thiourea in ethanolic sodium hydroxide solution
gave 4,5-dihydroisoxazoles and 5,6-dihydropyrimidine-2-(1H)-thiones. The prepared compounds were tested for antimicrobial activity against four different bacterial species displaying
different degrees of antibacterial activities or inhibitory actions. 相似文献
69.
Jan C. van Dam Michael R. Eman Johannes Frank Hans C. Lange Gijs W. K. van Dedem Sef J. Heijnen 《Analytica chimica acta》2002,460(2):307-218
The purpose of this study is to selectively and quantitatively analyze several glycolytic intermediates in cells of Saccharomyces cerevisiae using high-performance anion exchange chromatography (HPAEC) coupled to electrospray ionization tandem mass spectrometry for the analysis. A sodium hydroxide gradient is used to separate the glycolytic compounds and after the column sodium hydroxide is reduced by proton exchange with a membrane device prior to introduction to the mass spectrometer. The detection limits for 10 μl samples are down to the 0.4–5 pmol range. This corresponds for the intracellular metabolites to a range of 2–20 nmol per gram biomass dry weight (DW). Standard addition did reveal some influence of the sample matrix on the measured concentrations. Separation and analysis is hardly affected by the high sulfate and phosphate concentrations (1 mM) in the fermentation medium and by the intracellular matrix. Validation of the glucose-6-phosphosphate LC–MS–MS analysis results with enzymatic analysis showed an excellent agreement between the two methods. The suitability of the method was clearly shown by analyzing a series of steady state S. cerevisiae samples from a carbon limited aerobic chemostat culture. 相似文献
70.
Ahmed A. Abdel-Khalek El-Said M. Sayyah Eman S. H. Khalid 《Transition Metal Chemistry》1993,18(6):555-558
Summary The kinetics of oxidation of [CoII(EDTA)]2- (EDTA = ethylenediaminetetraacetate) by N-bromosuccinimide (NBS) in aqueous solution obey the equation: Rate = k
2
K
3[CoII]T[NBS]/{1 + [H+]/K
2 + K
3[NBS]} where k
2 is the rate constant for the electron-transfer process, K
2 the equilibrium constant for the dissociation of [CoII(EDTAH)(H2O)]– to [CoII(EDTA)(OH)]3– and K
3 the pre-equilibrium formation constant. The activation parameters are reported. It is proposed that electron transfer proceeds via an inner-sphere mechanism with the formation of an intermediate which slowly generates hexadentate[CoIII(EDTA)]–.Abstracted from the M.Sc. thesis of Eman S. H. Khaled. 相似文献