Determination of Specific Heats Using Isothermal Microcalorimetry

The specific heat capacities (c_p) for the brain and muscle equivalent liquids were determined with isothermal heat conduction microcalorimetry (IMC) and differential scanning calorimetry (DSC). IMC was found to afford an accurate technique to measure c_p for solid and liquid samples, when an appropriate reference is employed. The accuracy of obtained c_p values was estimated to be better than 0.7% with the equivalent liquids. Intercomparison with a conventional isoperibolic calorimeter showed an excellent agreement within the estimated uncertainty of the isoperibolic calorimeter (±3%). Additionally, suitability of different kinds of IMC sample vessels was tested, and the standard electrical calibration procedure of IMC was evaluated through the determination of c_p with and without a reference material. This revised version was published online in July 2006 with corrections to the Cover Date.     

Investigation on the thermal decomposition some heterodinuclear NiII-MII complexes prepared from ONNO type reduced Schiff base compounds ( M II=ZnII, CdII)

N,N′-bis(salicylidene)-1,3-propanediamine (LH₂), N,N′-bis(salicylidene)-2,2′-dimethyl-1,3-propanediamine (LDMH₂), N,N′-bis(salicylidene)-2-hydroxy-1,3-propanediamine (LOH₃), N,N′-bis(2-hydroxyacetophenylidene)-1,3-propanediamine (LACH₂) and N,N′-bis(2-hydroxyacetophenone)-2,2′-dimethyl-1,3-propanediamine (LACDMH₂) were synthesized and reduced to their phenol-amine form in alcoholic media using NaBH₄ (L^HH₂, LDM^HH₂, LOH^HH₂, LAC^HH₂ and LACDM^HH₂). Heterodinuclear complexes were synthesized using Ni(II), Zn(II) and Cd(II) salts, according to the template method in DMF media. The complex structures were analyzed using elemental analysis, IR spectroscopy, and thermogravimetry. Suitable crystals of only one complex were obtained and its structure determined using X-ray diffraction, NiLAC^H·CdBr₂·DMF₂, space group orthorhombic, Pbca, a=20.249, b=14.881, c=20.565 ? and Z=8. The heterodinuclear complexes were seen to be of [Ni·ligand·MX₂·DMF₂] structure (ligand=L^H2−, LDM^H2−, LOH^H2−, LAC^H2−, LACDM^H2−, M=Zn^II, Cd^II, X=Br⁻, I⁻). Thermogravimetric analysis showed irreversible bond breakage of the coordinatively bonded DMF molecules followed by decomposition at this temperature.     

The periodic table of urea derivative: small molecules of zinc(II) and nickel(II) of diverse antimicrobial and antiproliferative applications

Molecular Diversity - Two complexes of Zn(II) and Ni(II) ions with the urea derivative, 2-benzimidazolyl-urea (BZIMU), of formulae [ZnBZIMU)2(H2O)](NO3)2 (1) and [Ni(BZIMU)2(CH3CH2OH)2](NO3)2 (2)...     

The effects of temperature and hydrostatic pressure on the photoionization cross-section and binding energy of shallow donor impurities in quantum dots

Using a variational approach, we have calculated the hydrostatic pressure and temperature effects on the donor impurity related photoionization cross-section and impurity binding in GaAs/GaAlAs quantum dots. Our calculations have revealed the dependence of the photoionizaton cross-section and the impurity binding on temperature and hydrostatic pressure.     

The effects of temperature and hydrostatic pressure on the photoionization cross-section and binding energy of impurities in quantum-well wires

Using a variational approach, we have calculated the donor impurity related photoionization cross-section and impurity binding in GaAs/GaAlAs quantum-well wires under different temperature and hydrostatic pressure conditions. Our calculation have revealed the dependence of the photoionization cross-section and the impurity binding on temperature and hydrostatic pressure.     

Monobridged Si2H4

The rotational spectrum of a new monobridged isomer of Si(2)H(4), denoted here as H(2)Si(H)SiH, has been detected by Fourier transform microwave spectroscopy of a supersonic molecular beam through the discharge products of silane. On the basis of high-level coupled cluster theory, this isomer is calculated to lie only 7 kcalmol above disilene (H(2)SiSiH(2)), the most stable isomeric arrangement of Si(2)H(4), and to be fairly polar, with a calculated dipole moment of mu = 1.14 D. The rotational spectrum of H(2)Si(H)SiH exhibits closely spaced line doubling, characteristic of a molecule undergoing high-frequency inversion. Transition state calculations indicate that inversion probably occurs in two steps: migration of the bridged hydrogen atom to form silylsilylene, H(3)SiSiH, and then internal rotation of the SiH(3) group, followed by the reverse process. The potential energy surface for this type of inversion is quite shallow, with a barrier height of only 2-3 kcalmol. Searches for the rotational lines of silylsilylene, calculated to be of comparable stability to H(2)Si(H)SiH but about five times less polar (mu = 0.23 D), have also been undertaken, so far without success, even though strong lines of H(2)Si(H)SiH have been detected. The favorable energetics and high polarity of monobridged Si(2)H(4) with respect to either disilene or silylsilylene make it a plausible candidate for radioastronomical detection in sources such as IRC + 10216, where comparably large silicon molecules such as SiS, SiC(3), and SiC(4) have already been discovered.