Intuitionistic weak arithmetic

We construct -framed Kripke models of i₁ and i₁ non of whose worlds satisfies xy(x=2yx=2y+1) and x,yzExp(x, y, z) respectively. This will enable us to show that i₁ does not prove ¬¬xy(x=2yx=2y+1) and i₁ does not prove ¬¬x, yzExp(x, y, z). Therefore, i₁¬¬lop and i₁¬¬i₁. We also prove that HAl₁ and present some remarks about i₂. Mathematics Subject Classification (2000):03F30, 03F55, 03H15.     

Photooxidation of Ethylbenzene with TiO<Subscript>2</Subscript> and Metal Coated TiO<Subscript>2</Subscript> and its Kinetics

Summary. Photooxidation of ethylbenzene with oxygen to give ethylbenzene hydroperoxide has been achieved in a stirred photochemical reactor that was cooled by a water system by irradiation with a 400W high-pressure mercury lamp and using TiO₂ powder and metal coated TiO₂. The effects of the amount of copper or silver coated on TiO₂ and of the temperature on the rate of oxidation have been investigated. It is suggested that thermal cleavage of the O–O bond and photochemically generated singlet oxygen should be considered as the initiating step in a radical chain mechanism. An optimum loading of 6% Ag or 4–5% Cu was observed for photooxidation of ethylbenzene.     

Bis[N,N′‐(2‐chlorobenzylidene)ethylenediamine‐κ2N,N′]copper(I) dichloridocuprate(I) acetonitrile solvate

The 1:1 adduct of N,N′‐bis(2‐chlorobenzylidene)ethylenediamine (cb₂en) with copper(I) chloride proves to be an ionic compound with Cu^I‐centred cations and anions, [Cu(C₁₆H₁₄Cl₂N₂)₂][CuCl₂]·CH₃CN. In the cation, the Cu^I atom has a flattened tetrahedral coordination geometry, with a small bite angle for the chelating ligands, which form a double‐helical arrangement around the metal centre. The anion is almost linear, as expected. The packing of the cations involves intermolecular π–π interactions, which lead to columns of translationally related cations along the shortest unit‐cell axis, with anions and solvent molecules in channels between them.     

Novel Nitrite Membrane Sensor Based on Cobalt(II) Salophen for Selective Monitoring of Nitrite Ions in Biological Samples

A novel PVC-based membrane sensor based on the Co(II)-salophen complex (CSC) is described. The electrode revealed a Nernstian response over a wide nitrite ion concentration range (1.0×10^–6–1.0×10^–1M). The detection limit of the sensor is 8.0×10^–7M. The best performance was obtained with a membrane composition of 33% PVC, 61% ortho-nitrophenyloctyl ether, 3% cobalt(II)-salophen, and 3% hexadecyltrimethylammonium bromide. The potentiometric response of the sensor is independent of the pH of solution in the pH range 4.5–11.9. The electrode exhibits a very fast response time and good selectivity over a variety of common inorganic and organic anions, including fluoride, bromide, iodide, sulfite, nitrate, thiocyanate, thriiodide and perchlorate. The selectivity behavior of the proposed sensor shows substantial improvements compared to the previously reported electrodes for nitrite ion. The membrane sensor can be used for at least 2 months without any divergence in potential. The electrode was successfully applied to the monitoring of nitrite ion in water, sausage, flour, wheat, cheese and milk.     

Photooxidation of Ethylbenzene with TiO 2 and Metal Coated TiO 2 and its Kinetics

Photooxidation of ethylbenzene with oxygen to give ethylbenzene hydroperoxide has been achieved in a stirred photochemical reactor that was cooled by a water system by irradiation with a 400W high-pressure mercury lamp and using TiO₂ powder and metal coated TiO₂. The effects of the amount of copper or silver coated on TiO₂ and of the temperature on the rate of oxidation have been investigated. It is suggested that thermal cleavage of the O–O bond and photochemically generated singlet oxygen should be considered as the initiating step in a radical chain mechanism. An optimum loading of 6% Ag or 4–5% Cu was observed for photooxidation of ethylbenzene.     

Monitoring liposome-mediated delivery and fate of an antisense drug in cell extracts and in single cells by capillary electrophoresis with laser-induced fluorescence

Capillary electrophoresis with laser-induced fluorescence (CE-LIF) detection was used for evaluation of the effectiveness of delivery and fate of a model 25-mer DNA-based phosphorothiate antisense drug in cells. The antisense molecule was delivered to the cells through a simple incubation and by using a cationic liposome (Cytofectin GS 3815). The cationic lipid interacted with the negatively charged antisense to form a more positively charged complex. It was observed that uptake of the liposome-antisense complex by the cell was dependent on concentration of lipid, duration of transfection, and the cell type. The antisense drug interacted with intracellular components such as proteins and additional steps were needed to quantify the free antisense. Proteinase-K was able to release antisense from proteins. However, the addition of sodium dodecyl sulfate (SDS) to the sample or running buffer was more effective than Proteinase-K to release both naked and liposome-bound antisense from the cellular materials. Analysis of single HeLa cells for uptake of the unbound and liposome-complexed antisense revealed averages of 8.9x10(-19) moles and 4.9x10(-18) moles, respectively. The amount of uptake, however, varied greatly among individual cells and depended on the delivery method. With liposome-mediated delivery, the relative standard deviation (RSD) for the amount of antisense in individual cells was 130%, while the variation was much smaller (RSD = 45%) when the cells were incubated with the unbound antisense. These uptake variations agreed with those obtained from flow cytometry analysis.     

On magnetophoretic separation of blood cells using Halbach array of magnets

Meccanica - Magnetophoretic separation has gained much attention in recent years due to its easy application and low-cost fabrication compared to other active particle separation techniques. Due to...