One-Dimensional Matrix-Fracture Transfer in Dual Porosity Systems with Variable Block Size Distribution

Most of the developed models for fractured reservoirs assume ideal matrix block size distribution. This assumption may not be valid in reality for naturally fractured reservoirs and possibly lead to errors in prediction of production from the naturally fractured reservoirs especially during a transient period or early time production from the matrix blocks. In this study, we investigate the effect of variable block size distribution on one- dimensional flow of compressible fluids in fractured reservoirs. The effect of different matrix block size distributions on the single phase matrix-fracture transfer is studied using a recently developed semi-analytical approach. The proposed model is able to simulate fluid exchange between matrix and fracture for continuous or discrete block size distributions using probability density functions or structural information of a fractured formation. The presented semi-analytical model demonstrates a good accuracy compared to the numerical results. There have been recent attempts to consider the effect of variable block size distribution in naturally fractured reservoir modeling for slightly compressible fluids with a constant viscosity and compressibility. The main objective of this study is to consider the effect of variable block size distribution on a one-dimensional matrix-fracture transfer function for single-phase flow of a compressible fluid in fractured porous media. In the proposed semi-analytical model, the pressure variability of viscosity and isothermal compressibility is considered by solving the nonlinear partial differential equation of compressible fluid flow in the fractured media. The closed form solution provided can be applied to flow of compressible fluids with variable matrix block size distribution in naturally fractured gas reservoirs.     

Synthesis and Reactivity of Functionalized Binary and Ternary Thiometallate Complexes [(RT)4S6], [(RSn)3S4]2−, [(RT)2(CuPPh3)6S6], and [(RSn)6(OMe)6Cu2S6]4− (R=C2H4COOH,CMe2CH2COMe; T=Ge,Sn)

Caged chalcogens : A series of novel, functionalized T_nS_m cages (T=Ge, Sn; n/m=4:6, 3:4) with terminal COO(H) or COMe groups were synthesized and show further reactivity toward Cu^I complexes (an example of which is shown here) and to hydrazines. This led to the generation of functionalized Cu/T/S clusters or the formation of Schiff bases at the C?O groups, respectively, with or without further fragmentation of the T/S core.

     

The effects induced by proton irradiation on structural characteristics of nuclear graphite

A grade TSX graphite was irradiated by a 2.5 MeV proton and a dose of 1.47 × 10¹⁸ ion cm⁻² at 330 K. The displacement per atom under this irradiation condition was about 0.02. The lattice parameter, crystallite size and the vacancies density in the graphite was measured before and after irradiation. It was found that the proton irradiation led to an increase in the volume of the sample. The volume change in the irradiated sample was confirmed by atomic force and scanning electron microscopes observations as increased roughness and pore size. Also, FTIR results showed that graphite is slightly oxidized by irradiation.

     

Surfactant to dye binding degree method for the determination of fluvoxamine maleate and citalopram hydrobromide in pharmaceuticals

The surfactant to dye binding degree (SBDB) methodology was used to determine fluvoxamine maleate and citalopram hydrobromide. Neutral red and sodium dodecyl sulfate (SDS) were used as the dye and surfactant, respectively, to form dye-surfactant aggregates. When a cationic drug is added to dye-surfactant mixture, it interacts with the surfactant and decreases the dye-surfactant binding degree. This decrease is proportional to the drug concentration. This was measured by monitoring the absorbance changes of the dye at 532 nm. Under the optimum conditions, the calibration graphs were linear over the range of 1.2–15 μg mL⁻¹ and 1.1–15 μg mL⁻¹ for fluvoxamine maleate and citalopram hydrobromide, respectively. The detection limits (signal to noise ratio = 3) were found to be 0.37 and 0.35 μg mL⁻¹, for fluvoxamine maleate and citalopram hydrobromide, respectively.      

Mechanism of methanol decomposition by non-thermal plasma

In this investigation available experimental data in the literature were used to propose a reaction mechanism for the destruction of methanol using non-thermal plasma technology. In a recent study [M. Derakhshesh, J. Abedi, M. Omidyeganeh, Modeling of hazardous air pollutant removal in the pulsed corona discharge, Phys. Lett. A 373 (2009) 1051–1057.] the reactor performance equation for destruction of pollutants was developed. The order of reaction for methanol decomposition is estimated using a recently developed performance model and the available experimental data. It is found that that methanol decomposition reaction follows order one. In addition, using the experimental data available in the literature the rate constant for methanol decomposition is obtained and the overall rate was compared with our previous study.     

Humidity Sensing Properties of the Sensor Based on V‐doped Nanoporous Ti0.9Sn0.1O2 Thin Film

Vanadium doped nanoporous Ti_0.9Sn_0.1O₂ thin film has been prepared on an alumina substrate by sol‐gel method with Pluronic P123 as the organic template, and humidity sensing properties of it has been investigated. It is found that V‐doped nanoporous Ti_0.9Sn_0.1O₂ thin film shows good humidity sensing properties, and impendence of it decreases more than four orders of magnitude in the relative humidity (RH) range of 11%–95% at 25°C. The response and recovery time of this sensor are about 13 and 17 s, respectively. High sensitivity, narrow hysteresis loop, rapid response and recovery, prominent stability and good repeatability are obtained. A possible mechanism is suggested to explain the humidity sensitive properties.     

Enhancement of the chemiluminescence of permanganate-formaldehyde system by gold/silver nanoalloys and its application to trace determination of melamine

We have examined the specificity of electrosynthesized poly-o-phenylenediamine as a kind of material molecularly imprinted with metal chelates. Molecularly imprinted polymers (MIPs) were prepared in situ by an electrochemical method. The EDTA chelate complexes of Cu(II), Zn(II), Fe(III) and Cd(II) ions were used as templates of the MIPs deposited on a gold electrode of a quartz crystal microbalance (QCM). The binding ability and specificity of the MIPs were investigated via the frequency response of the QCM to the adsorption of the template chelates and their analogs. Linear relationships are observed between the frequency shift and the concentration of the template chelates over a typical range of ~10^?6 to ~10^?4?mol·L^?1. The results reveal good binding specificity of such MIPs for their templates over structurally related analogs, but the selectivity coefficients are less significant than that for enantiomers. The results also suggest no significant correlation between binding specificity and the ionic (or atomic) radius of the investigated metal ions. The observed specificity is qualitatively attributed to the overall conformational difference of the metal-EDTA complexes resulting from their difference in both ionic radius and electronic structures.

Triphenylphosphine-catalysed one-pot synthesis of γ-butyrolactone derivatives and highly substituted enones via reaction of dimethyl acetylenedicarboxylate and aryl aldehydes

The reaction between dimethyl acetylenedicarboxylate and various aryl aldehydes in the presence of triphenylphosphine leads to unsaturated γ-butyrolactone derivatives and highly substituted enones in fairly good yields at room temperature.     

Syntheses and Structures of Organotin(IV) Thioesters of N‐Phthaloylamino Acids

Five organotin(IV) thioesters of N‐phthaloyl amino acids with the general formulae R₃SnL (R = Me, Ph) and nBu₂SnL₂ were synthesized with L = N‐phthaloyl‐thioalanine and N‐phthaloyl‐thioleucine. The structures of trimethyltin(IV) N‐phthaloyl‐thioleucinate ( 1 ), trimethyltin(IV) N‐phthaloyl‐thioalaninate ( 2 ), triphenyltin(IV) N‐phthaloyl‐thioleucinate ( 3 ), triphenyltin(IV) N‐phthaloyl‐thioalaninate ( 4 ), and di‐n‐butyltin(IV) di‐N‐phthaloyl‐thioalaninate ( 5 ) were characterized by means of X‐ray diffractometry. Quantumchemical investigations served to clarify several structural peculiarities of the isolated compounds.