Depolymerization Study of Pakistani Lignite Coal Influence of Pre‐treatments on Product Slate

Influence of pretreatments, i.e., demineralization and pre‐soaking in some solvents on the yields of liquefied products obtained from hydro‐depolymerization of Pakistani coal in a pool of hydrogen has been discussed. Results of hydrogenation experiments demonstrated that demineralizing the coal sample prior to liquefaction caused the yields to decrease compared with the virgin coal samples. The contribution of mineral matter of coal has been evaluated by comparing the yields of liquid products of virgin and leached samples. Increase in the yields obtained from the hydrogenation experiments of swollen coal samples was not satisfactorily significant.     

A photochemical method for patterning the immobilization of ligands and cells to self-assembled monolayers

This work describes a chemically well defined method for patterning ligands to self-assembled monolayers (SAMs) of alkanethiolates on gold. This method begins with monolayers presenting a nitroveratryloxycarbonyl (NVOC)-protected hydroquinone which is photochemically irradiated to reveal a hydroquinone group. The resulting hydroquinone is then oxidized to the corresponding benzoquinone, providing a site for the Diels-Alder mediated immobilization of ligands. The rate constant for the photochemical deprotection is 0.032 s(-1) (with an intensity of approximately 100 mW/cm(2) between 355 and 375 nm), corresponding to a half-life of 21 s. The hydroquinone is oxidized to the benzoquinone using either electrochemical or chemical oxidation and then functionalized by reaction with a cyclopentadiene-tagged ligand. Two methods for patterning the immobilization of ligands are described. In the first, the substrate is illuminated through a mask to generate a pattern of hydroquinone groups, which are elaborated with ligands. In the second method, an optical microscope fit with a programmable translational stage is used to write patterns of deprotection which are then again elaborated with ligands. This technique is characterized by the use of well-defined chemical reactions to control the regions and densities of ligand immobilization and will be important for a range of applications that require patterned ligands for biospecific interactions.     

Enhanced Sensitive Electrochemical Sensor for Simultaneous Catechol and Hydroquinone Detection by Using Ultrasmall Ternary Pt-based Nanomaterial

The simple and effective method for the novel synthesis of Pt-based nanoparticle was presented with high efficiency. The sensitive catalyst for the simultaneous detection of catechol and hydroquinone was prepared by depositing ternary metal complex on fluorine-doped tin-oxide (FTO). The composition and morphology of nanomaterials were characterized by TEM, HRTEM, XRD, XPS, and EDS (energy dispersive spectroscopy). The size of the Pt-based nanomaterial was about 5±1 nm. The electrochemical performance of the modified catalyst was studied by CV, DPV, and EIS. The modified PtNiCu@FTO catalyst possessed good electro-oxidation activity for hydroquinone and catechol and used for simultaneous detection of catechol and hydroquinone at scan rate of 20 mV s⁻¹ (vs. Ag/AgCl). Detection responses were found in the ranges of 5–2900 μM for hydroquinone and 5–3000 μM for catechol. The detection limits (LOD) for HQ and CC were observed as 0.35 and 0.29 μM, respectively. The sensitivity of HQ and CC were 1515.55 and 1485 μA mM⁻¹ cm⁻², respectively. The prepared nanomaterial were effectively applied for the determination of CC and HQ in real samples.     

A hybrid nanofluid analysis near a parabolic stretched surface

Two dimensional incompressible steady viscous nano-fluid flow with the impacts of heat generation and porous medium is examined numerically. For this objective Ti₆Al₄v are taken as nano-particles dispersed in different base fluids such as methanol, engine oil and water. Basically in this study we will compare three different nano-fluids to assess their flow behaviour and thermal performance. The flow model is developed under certain assumptions. The two dimensional non-linear PDEs are converted into non-linear ODEs with suitable transformation. The numerical procedure is adopted to find the results by using Bvp4c technique in MATLAB. Moreover, graphs are generated for various parameters against the temperature and velocity profiles. The fluid behaviour for different parameter is examined on velocity and temperature profile. It is depicted that for high values of volume fraction and curvature parameter nano-particles leads to high velocity and temperature profile. Moreover, velocity profile decreases for permeability parameter, while temperature profile enhances for heat generation parameter. The influence of Nusselt number and skin friction also assessed. The model of entropy generation is also presented.     

Development of Yttrium and Iron Oxide Thin Films via AACVD Method for Photooxidation of Water

Russian Journal of Applied Chemistry - Owing to high stability, metal oxide-based ceramic thin films are of great interest for photocatalytic oxidation of water. Therefore, the current research is...     

Effect of ion irradiation induced defects on the excess conductivity of Cu1−xTlxBa2Ca1Cu2O8−δ superconductor thin films

The Cu_1?xTl_xBa₂Ca₁Cu₂O_8?δ superconductor thin film samples were bombarded with protons, Si and Au ions of energies 6, 20 and 20 MeV respectively using 5MV tandem pelletron accelerator at Experimental Physics Labs. Each un-irradiated sample had different values of normal state resistivity and the zero resistance critical temperature. The zero resistivity critical temperature has been increased after the irradiation by Si and Au ions. The fluctuation induced conductivity (FIC) analysis of the as-prepared and the ion irradiated samples were performed in the light of Aslamasov–Larkin (AL) theory. The FIC analysis has shown three dimensional (3D) fluctuations in the order parameter in all the samples along with a cross-over to two dimensional (2D) fluctuations at higher temperature. The 3D–2D cross-over temperature has been shifted to higher values after the ion irradiation. Moreover, a direct correlation between the zero resistivity critical temperature, 2D–3D cross-over temperature (T_LD) and superconductivity fluctuation temperature (T_scf) was observed. These studies have shown that the fluctuation induced conductivity (excess conductivity) depends on the density of defects and is independent of their nature.     

Stochastic vs deterministic programming in water management: the value of flexibility

In the paper we develop a two stage scenario-based stochastic programming model for water management in the Indus Basin Irrigation System (IBIS). We present a comparison between the deterministic and scenario-based stochastic programming model. Our model takes stochastic inputs on hydrologic data i.e. inflow and rainfall. We divide the basin into three rainfall zones which overlap on 44 canal commands. Data on crop characteristics are taken on canal command levels. We then use ten-daily and monthly time intervals to analyze the policies. This system has two major reservoirs and a complex network of rivers, canal head works, canals, sub canals and distributaries. All the decisions on hydrologic aspects are governed by irrigation and agricultural development policies. Storage levels are maintained within the minimum and maximum bounds for every time interval according to a power generation policy. The objective function is to maximize the expected revenue from crops production. We discuss the flexibility of two stochastic optimization models with varying time horizon.