Photo-oxidation of 5-acetyl-3,4-dihydropyrimidin-2(1H)-ones

A variety of Biginelli 5-acetyl-3,4-dihydropyrimidin-2(1H)-ones are efficiently oxidized to their corresponding pyrimidin-2(1H)-one derivatives upon UV irradiation under argon atmosphere in chloroform solution. The nature of the additional substituent on the phenyl ring located on C-4 of the heterocyclic ring influences the rate of reaction. An electron-transfer induced photoreaction is proposed based on the formation of HCl and CH₂Cl₂.     

Fermi velocity enhancement in monolayer and bilayer graphene

In single-layer graphene sheets non-local interband exchange leads to a renormalized Fermi-surface effective mass which vanishes in the low carrier-density limit. We report on a comparative study of Fermi surface effective mass renormalization in single-layer and AB-stacked bilayer graphene. We explain why the mass does not approach zero in the bilayer case, although its value is still strongly suppressed.     

Markov Properties of Electrical Discharge Current Fluctuations in Plasma

Using the Markovian method, we study the stochastic nature of electrical discharge current fluctuations in the Helium plasma. Sinusoidal trends are extracted from the data set by the Fourier-Detrended Fluctuation analysis and consequently cleaned data is retrieved. We determine the Markov time scale of the detrended data set by using likelihood analysis. We also estimate the Kramers-Moyal’s coefficients of the discharge current fluctuations and derive the corresponding Fokker-Planck equation. In addition, the obtained Langevin equation enables us to reconstruct discharge time series with similar statistical properties compared with the observed in the experiment. We also provide an exact decomposition of temporal correlation function by using Kramers-Moyal’s coefficients. We show that for the stationary time series, the two point temporal correlation function has an exponential decaying behavior with a characteristic correlation time scale. Our results confirm that, there is no definite relation between correlation and Markov time scales. However both of them behave as monotonic increasing function of discharge current intensity. Finally to complete our analysis, the multifractal behavior of reconstructed time series using its Keramers-Moyal’s coefficients and original data set are investigated. Extended self similarity analysis demonstrates that fluctuations in our experimental setup deviates from Kolmogorov (K41) theory for fully developed turbulence regime.     

Synthesis of Nitroalkanes from Alkylhalides under Mild and Nonaqueous Conditions by Using Polymer Supported Nitrites

Alkyl halides are efficiently converted to their corresponding nitroalkanes under mild and nonaqueous conditions by using polymer supported nitrites. The polymeric reagent is regenerable.     

Application of Monte Carlo simulation method to polymerization kinetics over Ziegler–Natta catalysts

In the current work, the Monte Carlo simulation method was applied to ethylene polymerization over Ziegler–Natta catalysts. As expected, polymerization over each center of a Ziegler–Natta catalyst leads to a polymer having a Schultz–Flory molecular weight distribution. Notwithstanding, the total molecular weight distribution obtained by all catalyst centers together is at least twice as broad as that of each center. As another interesting finding, the introduction of hydrogen to the reaction deactivates the catalyst active centers and thereby reduces the catalyst activity. Nevertheless, it does not mainly affect the polymerization kinetics. In addition, the polymer molecular weight falls as hydrogen is added to the reaction since it acts as a strong transfer agent. The same effect is seen when cocatalyst concentration increases. Hydrogen also widens the polymer molecular weight distribution. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 41: 45–56, 2009     

Mixed-ligand complexes of copper(I) with diimines and phosphines: Effective catalysts for the coupling of phenylacetylene with halobenzene

New copper(I) mixed-ligand complexes 1–4 of the formula Cu(N–N)PR₃X, where N–N = 1,10-phenanthroline (phen), 2,2′-bipyridine (bpy), 5,5′-dimethyl-2,2′-bipyridine (5,5′dimbpy) and PR₃ = tricyclohexylphosphine, tris(2-cyanoethyl)phosphine and isopropyldiphenylphosphine, have been synthesized. The complexes were characterized by EA, IR, NMR and single crystal X-ray diffraction. The solution fluorescence emission spectra were measured. The single crystal X-ray analysis showed that the copper(I) ion is four-coordinate with a distorted tetrahedral geometry. The complexes catalyze the formation of diphenylacetylene from the coupling of halobenzene with phenylacetylene. The complex Cu(5,5′-dimethylbpy)P{(cyhexyl)₃}I showed the highest catalytic activity. At room temperature all four complexes exhibit, in dichloromethane, emission maxima in the 329–344 nm range, corresponding to intra-ligand excited states.     

Synthesis of semi-biodegradable crosslinked microspheres for the delivery of 1,25 dihydroxyvitamin D3 for the treatment of hepatocellular carcinoma

It has been demonstrated that 1,25 dihydroxyvitamin D₃ (1,25(OH)₂VD₃) can inhibit the proliferation of cancer cells, including colorectal and hepatocellular cells which are mainly responsible for liver cancer. However, the use of 1,25(OH)₂VD₃ is hampered due to the development of hypercalcaemia. We hereby report a promising technique in liver cancer treatment by utilizing crosslinked microspheres prepared by polymerization as a carrier to control the release of 1,25(OH)₂VD₃ or hydrophobic drug in general at targeted sites over a long period. Microspheres in the size range of 35 μm were prepared and the drug was loaded to these poly(vinyl neodecanoate-crosslinked-ethyleneglycol dimethacrylate) microspheres after polymerization. The release study has shown that up to 1% of the drug was released after 40 days. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and direct contact cytotoxicity assay using HT-20 and L929 confirm the non-toxicity of these spheres.     

MICROBE-METAL-INTERACTIONS FOR THE BIOTECHNOLOGICAL TREATMENT OF METAL-CONTAINING SOLID WASTE

In nature, microbes are involved in weathering of rocks, in mobilization of metals from minerals, and in metal precipitation and deposition. These microbiological principles and processes can be adapted to treat particulate solid wastes. Especially the microbiological solubilization of metals from solid minerals （termed bioleaching） to obtain metal values is a well-known technique in the mining industry. We focus here on non-mining minerai wastes to demonstrate the applicability of mining-based technologies for the treatment of metal-containing solid wastes. In the case study presented, microbial metal mobilization from particulate fly ash （originating from municipal solid waste incineration） by Acidithiobacilli resulted in cadmium, copper, and zinc mobilization of 〉80%, whereas lead, chromium, and nickel were mobilized by 2, 11 and 32%, respectively. In addition, the potential of HCN-forming bacteria （Chromobacterium violaceum, Pseudornonas fluorescens） was investigated to mobilize metals when grown in the presence of solid materials （e.g.,copper-containing ores, electronic scrap, spent automobile catalytic converters）. C. violaceum was found capable of mobilizina nickel as tetracyanonickelate from fine-grained nickel powder. Gold was microbially solubJlized as dicyanoaurate from electronic waste. Additionally, cyanide-complexed copper was detected during biological treatment of shredded printed circuit-board scraps. Water-soluble copper and platinum cyanide were also detected during the treatment of spent automobile catalytic converters.     

A simple flow injection spectrophotometric determination of nitrite based on its reaction with thiourea.

A simple flow injection spectrophotometric method for the determination of nitrite is described. Nitrite injected into the flow system reacts with thiourea in acidic medium and the generated thiocyanate ion reacts with Fe(III) in the reagent solution to produce a highly colored product. The influences of chemical and physical parameters including reagent concentrations, sample volume injected, flow rates of the carrier and reagent solutions, reaction coil length and reaction temperature, were studied and optimum values of these parameters were established. Under the optimum conditions, the calibration curve for nitrite was linear over the concentration range 0.36 - 90 microg ml(-1) without preconcentration and over the range 3.8 - 500 ng ml(-1) with a simple online preconcentration step using an anion exchange column. The corresponding detection limits were 0.36 micro ml(-1) and 3.8 ng ml(-1), respectively. Up to 25 samples can be analyzed per hour, with an average relative standard deviation of < or = 1.2%. Interferences by various foreign ions were studied and the method was applied to the determination of nitrite in water and spiked water samples.