On the Diffusion in a Lattice Gas Model: Group-Theoretic Approach

Motivated by some recent results concerning the model of a noninteracting one-dimensional lattice gas with an order preservation of particles where multiple occupancy of the sites is not excluded, we give new symmetries and new reductions of the corresponding continuum nonlinear partial differential equation. Closed-form analytic solutions are found.     

Sesquialkoxide von Gallium und Indium

Sesquialkoxides of Gallium and Indium Treatment of GaMe₃ with one equivalent of HO^cHex in toluene at 20 °C leads to [Me₂GaO^cHex]₂ ( 4 ) under evolution of methane. The reaction of InMe₃ with two equivalents of HO^cHex leads under similar conditions not to [MeIn(O^cHex)₂]_n but to the sesquialkoxide [In{Me₂In(O^cHex)₂}₃] ( 5 ). 5 can be described also as [{Me₂InO^cHex)}₂{MeIn(O^cHex)₂}₂]. The use of an excess of cyclohexanol in boiling toluene gives the same result. Under these reflux conditions, the reaction of GaMe₃ with an excess of PhCH₂OH leads exclusively to another type of sequialkoxides, [Ga{MeGa(OCH₂Ph)₃}₃] ( 6 ). 4 — 6 were characterized by NMR, vibrational and MS spectra, as well as by X‐ray structure determinations. According to this, 4 forms centrosymmetrical and therefore planar Ga₂O₂ four‐membered rings. 5 and 6 possess basically the same structural motif, central M³⁺ ion ( 5 : In³⁺; 6 : Ga³⁺) coordinated by three metalate units ( 5 : [Me₂In(O^cHex)₂]^—; 6 : [MeGa(OCH₂Ph)₃]^—). The central M³⁺ ions have always coordination number (CN) six while the three surrounding metal ions possess CN 4. Because of the spectroscopic findings 6 must exist in two isomers (1:1). The C₃‐symmetrical isomer C₃‐ 6 was characterized by X‐ray analysis, while the isomer C₁‐ 6 could by described mainly by the complex NMR data.     

Preparation of the Ni-P composite coating co-deposited by nano TiC particles and evaluation of it's corrosion property

In current research, low carbon steel plates were coated by Ni-P electroless method. The effect of adding different concentrations (ranging from 0.01 g/l to 0.5 g/l) of TiC nano-sized particles to the plating bath on deposition rate, surface morphology and corrosion behavior of Ni-P-TiC composite coatings were investigated. The surface morphology and the relevant structure were evaluated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Corrosion behavior of the coated steel was evaluated by electrochemical impedance spectroscopy (EIS) and polarization techniques. The results showed that addition of TiC nano-particles to Ni-P electroless bath not only changes the surface morphology of Ni-P coating, but also improves corrosion resistance of the steel in comparison with TiC free Ni-P electroless coating. In addition, the deposition rate of coating was also affected by incorporation of TiC particles. It was also found that improvement in corrosion resistance largely depends on the phosphorous and TiC concentrations on the coatings.     

Simultaneous determination of cyproterone acetate and ethinylestradiol in tablets by derivative spectrophotometry

Derivative spectrophotometry offers a useful approach for the analysis of drugs in multi-component mixtures. In this study a third-derivative spectrophotometric method was used for simultaneous determination of cyproterone acetate and ethinylestradiol using the zero-crossing technique. The measurements were carried out at wavelengths of 316 and 226 nm for cyproterone acetate and ethinylestradiol respectively. The method was found to be linear (r2>0.999) in the range of 0.5-6 mg/100 ml for cyproterone acetate in the presence of 35 microg/100 ml ethinylestsradiol at 316 nm. The same linear correlation (r2>0.999) was obtained in the range of 10-80 microg/100 ml of ethinylestradiol in the presence of 2 mg/100 ml of cyproterone acetate at 226 nm. The limit of determination was 0.5 mg/100 ml and 10 microg/100 ml for cyproterone acetate and ethinylestradiol respectively. The method was successfully applied for simultaneous determination of cyproterone acetate and ethinylestradiol in pharmaceutical preparations without any interferences from excipients.     

Uniform copper nanoparticles as an inexpensive and efficient catalyst for synthesis of novel β-carbonyl-1, 2, 3-triazoles in water medium

Copper nanoparticles as an efficient, inexpensive catalyst were prepared via ball milling for synthesis of β-carbonyl 1, 2, 3-triazoles from azido alcohol by click reaction in water. An extensive range of raw materials such as sodium azide, phenacyl bromide, epichlorohydrin, and terminal alkynes were used. Complete reduction of CuO in presence of NaBH₄ was done via ball milling with a ball-to-powder weight ratio of 50:1 under air atmosphere at room temperature. The final copper nanoparticles (Cu NPs) were characterized by SEM, EDX, XRD and FT-IR. The Cu NPs catalyzed one-pot three component synthesis of β-carbonyl 1, 2, 3-triazoles at room temperature with short reaction time and high product yields. The catalyst could be easily recovered and reused in several successive runs.

     

Reaktionen von Nitrilen mit tBuAsLi2

Reactions of Nitriles with ^tBuAsLi₂ ^tBuAsLi₂ reacts with the α‐acidic nitrile malonicaciddinitrile in THF/TMEDA under deprotonation and formation of the coordination polymer [{Li(TMEDA}{HC(CN)₂}]_n ( 1 ). The more base‐stable PhCN gives with ^tBuAsLi₂ under aromatization the salt [Li(Diglyme)₂][Li(TMEDA){As[NC(Ph)NC(Ph)]}₂] ( 2 ), containing a diazaarsolide. 1 and 2 were characterized by NMR and vibrational spectroscopy, mass spectrometry and X‐ray analyses. According to that, 1 contains in the solid state infinite helical chains of cations and anions, running along [010]. 2 consists of distorted octahedrally coordinated Li⁺ ion, [Li(diglyme)₂]⁺, and the complex anion [Li(TMEDA){As[NC(Ph)NC(Ph)]}₂]^‐ with a distorted tetrahedrally environment of the Li⁺ ion.     

Analytic Solutions for Asymmetric Model of a Rod in a Lattice Fluid

We consider the problem of determining analytically some exact solutions of the concentration u(x, y, t) of particles moving by diffusion and advection or drift. It is assumed that the advection is nonlinear. The driven diffusive flow is impeded by an impenetrable obstacle (rod) of length L. The exact solutions for u are evaluated for small and big values of vL/D, where v is the drift velocity and D is the diffusion coefficient. The results show that in some regions in the (x, y) plane the concentration first increases (or decreases) monotonically and then is nearly constant after some critical length L. The location at which u is nearly constant depends on the nature of the driving field v/D. This problem has relevance for the size segregation of particulate matter which results from the relative motion of different-size particles induced by shaking. Methods of symmetry reduction are used in solving the nonlinear advection-diffusion equation in (2+1) dimensions.     

New exact solutions of heat conduction in metals

We consider the way in which a solution to a class of nonlinear partial differential equationsS(u)u _t=(K(u)u_x)_x approaches the similarity form. The problem we solve is chosen for two main reasons: first the equation above is of widespread use in modeling physical situations and second it provides a tractable but significant example of a free boundary problem.