Spectroscopic,thermal, and X-ray diffraction studies of tetrakis(thiourea) palladium chloride bis (5,7-dimethyl[1,2,4]triazolo[1,5-a]pyrimidine dihydrate

The crystal and molecular structure of the title compound, ·[Pd(S=C(NH₂)₂)₄]Cl₂·2dmtp·2H₂O. has been determined and refined to a finalR=0.034. The cation is centrosymmetric with the Pd atom existing in a square planar geometry with two disparate Pd–S bond distances of 2.3129(9) and 2.292(1)Å. Interatomic parameters are reported for the first non-coordinated dmtp molecule; these suggest the predominance of a particular canonical form in the solid state. The lattice is stabilized via a series H-bonding contacts involving the thiourea. Cl^– and dmtp species. Crystals of [Pd(S=C(NH₂)₂)₄]Cl₂ · 2dmtp · 2H₂O are monoclinic with space groupP2₁/c, and unit cell dimensionsa=15.129(1),b=8.512(1),c=12.663(1) Å, =104.05(1)°.     

Das Picard-Prinzip und verwandte Fragen bei Störung von harmonischen Räumen

Ohne Zusammenfassung     

Layered petroleum reservoirs with cross-flows

Studied is a cylindrical reservoir consisting of three layers: a water-containing bottom layer, and two oil-containing top layers from whose upper layer oil is produced. For its solution, a corrected version of the finite Hankel transform for Neumann-Neumann boundary conditions was used together with numerical inversion of the Laplace transform. The effects of the water zone on the unsteady state pressure in the reservoir were evaluated at distances away from the well and at the well-bore itself. We found that the vertical pressure drop increases gradually with time and is more significant in the vicinity of the well-bore. For constant production and at any time t, smaller reservoirs experience higher pressure drops than larger ones. For the reservoir investigated, we found that for nondimensional time t _Dw <10⁴ the presence of a second fluid (water) has no effect on the pressure drop. Of all the formation and fluid properties investigated, porosity has the largest effect on pressure.Nomenclature c ₁, c ₂ Oil and water compressibilities, vol/vol/atm, vol/vol/psi - h Height of water zone from bottom of reservoir, cm, ft - h _D h/r _w , non-dimensional - H Height of reservoir, cm, ft - H _D H/r _w, non-dimensional - J ₀, J ₁ Bessel functions of the first kind, zero and first-order - K _r2, K _r1 Oil and water zones, horizontal permeabilities, darcies, md - K _z2, K _z1 Oil and water zones, vertical permeabilities, darcies, md - k ₁ n=1, 2, 3... - k ₂ n=1, 2, 3... - k _1,0 - k _2,0 - p(r, z, t) P(r, z, 0)–P(r, z, t), atm, psi - P(r, z, t) Pressure at any layer in the reservoir, atm, psi - P(r, z, 0) Initial pressure at any layer in the reservoir, atm, psi - P _D , non-dimensional - q Constant production rate of well, cc/sec, barrels/day - r Radius of reservoir, cm, ft - r _D r/r _w , non-dimensional - r _e Drainage radius, cm, ft - r _eD re/r _w , non-dimensional - r _w Well-bore radius, cm, ft - t Time, sec, hr - _Dw (k _r2 t)/( _{2 2} c ₂ r _w ² ), non-dimensional - Y ₀, Y ₁ Bessel functions of the second kind, zero and first-order - z Distance z measured vertically upward from bottom of reservoir, cm, ft - Z _D z/r _w , non-dimensional - z ₁ Height of the bottom of the producing layer, cm, ft - z _1D z ₁/r _w , non-dimensional - z ₂ Height of the top of the producing layer, cm, ft - z _2,D z ₂/r _w , non-dimensional - _n nth positive root of equation (18) - ₁ k _z1/k _r1, non-dimensional - ₂ k _z2/k _r2, non-dimensional - _{1 1 1} c ₁/k _r1, hydraulic diffusivity of layer I - _{2 2 2} c ₂/k _r2, hydraulic diffusivity of layers II and III - ₂, ₁ Viscosity of oil and water, cp, cp - _{n n} /r _w , l/cm, l/ft - ₂, ₁ Porosity of oil and water-filled zones, fraction - ( ₁/ ₂) (k _z2/k _z1), non-dimensional     

Synthesis and photochemical degradation of N-arylmethyl derivatives of the herbicide 3-amino-1,2,4-triazole

Reaction of an arylmethyl halide with 3-amino-1,2,4-triazole ( 1 ) allows the preparation of the three N-aryl-methyl derivatives of 1 bearing the substituent on the heterocyclic nitrogen atoms. In basic medium (methoxide anion in DMF or methanol, or in benzene by phase transfer catalysis), the isomers 3 and 5 substituted at N-1 and N-2 respectively are obtained, while the isomer 4 is isolated from neutral medium (DMF). The isomers 3 and 4 may be also prepared by cyclization of appropriate formylguanidinium derivatives. 3-Arylmethylamino-1,2,4-triazoles 2 may be obtained through reaction of 3-chloro-1,2,4-triazole ( 6 ) with arylmethylamines. Photolysis of the N-arylmethyl-3-amino-1,2,4-triazoles 2-5 in methanol or water-methanol mixture, induces homolytic and heterolytic cleavage of the arylmethyl-C-N bond giving rise to 3-amino-1,2,4-triazole ( 1 ). Thus, compounds 2-5 with arylmethyl groups able to absorb solar light may be considered as potential photoactivatable herbicides.     

q-Analogue of the Watanabe Unitary Transform Associated to the q-Continuous Gegenbauer Polynomials

We associate a family of Hilbert spaces H _q ^2;(D) of analytic functions on the unit disk D=z :|z|<1 the q-continuous Gegenbauer polynomials C _n (x;q) on the interval]–1;1[ and give a q-analogue of the unitary integral transform that Watanabe constructed from the Hilbert space L ²(]–1;1[;(1–x ²)^– dx onto the weighted Hilbert space H ^2;(D).     

Photocatalytic degradation of an azo reactive dye,Reactive Yellow 84, in water using an industrial titanium dioxide coated media

The photocatalytic degradation of an azo reactive dye, Reactive Yellow 84 (RY84), in aqueous solutions using industrial titanium dioxide coated non-woven paper was studied. The experiments were carried out to investigate the factors that influence the dye photocatalytic degradation, such as adsorption, initial concentration of dye, temperature, and solution pH. The experimental results show that adsorption is an important parameter controlling the apparent kinetics constant of degradation. The photocatalytic degradation rate was favored by a high concentration of solution in respect to Langmuir–Hinshelwood model. The degradation was enhanced by the temperature and was favored in acidic pH range.     

Molecularly Imprinted Polymers Combined with Electrochemical Sensors for Food Contaminants Analysis

Detection of relevant contaminants using screening approaches is a key issue to ensure food safety and respect for the regulatory limits established. Electrochemical sensors present several advantages such as rapidity; ease of use; possibility of on-site analysis and low cost. The lack of selectivity for electrochemical sensors working in complex samples as food may be overcome by coupling them with molecularly imprinted polymers (MIPs). MIPs are synthetic materials that mimic biological receptors and are produced by the polymerization of functional monomers in presence of a target analyte. This paper critically reviews and discusses the recent progress in MIP-based electrochemical sensors for food safety. A brief introduction on MIPs and electrochemical sensors is given; followed by a discussion of the recent achievements for various MIPs-based electrochemical sensors for food contaminants analysis. Both electropolymerization and chemical synthesis of MIP-based electrochemical sensing are discussed as well as the relevant applications of MIPs used in sample preparation and then coupled to electrochemical analysis. Future perspectives and challenges have been eventually given.