Erratum

Peculiar transitions in the optical spectra of Mn atoms isolated in argon matrices confirm the existence of Mn₂ molecule. The temperature variation of the absorption and MCD intensity in the range 13-27 K demonstrate that the Mn₂ molecule is antiferromagnetic and allows a precise determination of its ground-state exchange energy: J = ?10.3 ± 0.6 cm^?1.     

Integral equation formulation for buoyancy-driven convection problems

An integral equation formulation for buoyancy-driven convection problems is developed and illustrated. Buoyancy-driven convection in a bounded cylindrical geometry with a free surface is studied for a range of aspect ratios and Nusselt numbers. The critical Rayleigh number, the nature of the cellular motion, and the heat transfer enhancement are computed using linear theory. Green's functions are used to convert the linear problem into linear Fredholm integral equations. Theorems are proved which establish the properties of the eigenvalues and eigenfunctions of the linear integral operator which appears in these equations.     

Keggin Heteropolyacid Catalyzed Synthesis of Isoxazolo[5,4-d]pyrimidine-4,6(5H,7H)-diones at Room Temperature

Isoxazolo[5,4‐d]pyrimidine‐4,6(5H,7H)diones 2a – 2f have been synthesized from the reaction of ethyl 5‐amino‐3‐methyl‐4‐isoxazole carboxylate ( 1 ) with aryl isocyanates in the presence of Keggin heteropolyacid H₃[PW₁₂O₄₀] as a green solid acid catalyst at room temperature in a one‐pot process in good yields.     

Permanently oriented antibody immobilization for digoxin determination with a flow-through fluoroimmunosensor

This paper reports a new flow-through fluoroimmunosensor, the function of which is based on antibodies immobilized on an inmunoreactor of controlled-pore glass (CPG), for determination of digoxin, used in the treatment of congestive heart failure and artery disease. The immunosensor has a detection limit of 1.20 microg L(-1) and provides high reproducibility (RSD=4.5% for a concentration of 0.0025 mg L(-1), and RSD=6.7% for 0.01 mg L(-1)). The optimum working concentration range was found to be 1.2 x 10(-3)-4.0 x 10(-2) mg L(-1). The lifetime of the immunosensor was about 50 immunoassays; if stored unused its lifetime can be extended to three months. A sample speed of about 10-12 samples per hour can be attained. Possible interference from substances with structures similar to digoxin (morphine, heroin, tebaine, codeine, pentazocine and narcotine) was investigated. No cross-reactivity was seen at the highest digoxin: interferent ratio studied (1:100). The proposed fluoroimmunosensor was successfully used to determine digoxin concentrations in human serum samples.     

Comparison between optimized geometries and vibrational frequencies calculated by the DFT methods for the Anderson-type heteropolyanion: hexamolybdoaluminate(III), [AlIII(OH)6Mo6O18]3-

Optimized geometries and vibrational frequencies were calculated for the hexamolybdoaluminate(III), [AlIII(OH)6Mo6O18]3-, Anderson-type heteropolyanion with the HF, B3LYP, B3PW91, B3P86 and B1LYP methods of theory using the LanL2DZ, SDD and combination of LanL2DZ with 6-31G (d, p) basis sets. The agreement between the optimized and experimental geometries was in the decreasing order: HF, B3P86, B3PW91, B1LYP and B3LYP. The calculated frequencies by the B3LYP have the smallest mean root mean square (RMS) error. The effect of the basis set on the calculated bond lengths and frequencies by the density functional calculations (DFT) methods was minor. The agreement between the previously reported IR and Raman spectra and the calculated values is, in general, good.     

A two-dimensional potential function for bent hydrogen bonded systems. II-6-hydroxy-2-formylfulvene

A simple and practical method for treating the non-adiabatic proton tunneling in 6-hydroxy-2-formylfulvene was used. A two dimensional potential energy surface function, which couples OH stretching and in-plane bending modes, has been constructed for motion of hydrogen by the aid of quantum mechanical calculations at MP2/6-31G** level for a fixed skeleton geometry. This potential was used for calculation of energy levels from which a tunneling splitting of 181±14 cm⁻¹ was obtained in an excellent agreement with the experimental value of at least 150 cm⁻¹. The calculated barrier height for these results was about 26–27 kJ/mol. This method also assigns a broad band at about 1740 cm⁻¹ to the OH in-plane bending mode. The calculated hydrogen bond strength was estimated to be about 80 kJ/mol.