Exact solutions of solid-liquid phase-change heat transfer when subjected to convective boundary conditions

A closed-form expression is presented to find the location of solid-liquid interface motion in convection-dominated solidification and melting problems. In this regard, the solutions are expressed in terms of the generalized representations of error functions,E (u, v) andF (u, v), which are useful to heat-conduction problems with convective-type boundary conditions. It is demonstrated that for constant surface temperature, the interface solution reduces to the classical Neumann solution.     

Thermal studies of some aryloxides of titanium(IV)

Thermal behaviour of aryloxides of titanium(IV) of composition TiCl_n(OAr)_4?n (wheren=0→3 and OAr=OC₆Bu^t-4, OC₆H₄OMe-4 and OC₆H₂-Bu ₂ ^t -2,6?Me-4) has been studied by DTA and TG analysis. Multiple decomposition steps have been indicated by thermal weight losses which are both exothermic and endothermic as shown by DTA curves. Based upon the total % loss in weight; during entire decomposition titanium dioxide has been found to be the final residue in each case.     

4-t-Butylphenoxo complexes of oxovanadium(V)

Summary Complexes of composition [VOCl₂(OC₆H₄Bu-t-4)] (1) and [VOCl(OC₆H₄Bu-t-4)₂] (2) have been synthesized by the reaction of VOCl₃ with equimolar and bimolar amounts, respectively, of 4-t-BuC₆H₄OSiMe₃ in CCl₄ and characterized by physio-chemical techniques. The complexes react with -hydroxyaldehydes and ketones such as 2-hydroxybenzaldehyde (salicylaldehyde, salH), and 2-hydroxy-2-phenylacetophenone (benzoin, benzH), 2-hydroxyacetophenone (hapH) and also with the potassium salt of p-chlorobenzohydroxamic acid (KBHACl) in 11 and 12 molar ratios, to yield five- and six-coordinate complexes.     

Acceptor properties of titanium(IV) phenoxides

Summary Compounds of composition TiCl_4–n(OPh)_n · 2L (L = monodentate ligand, n = 1–4) have been prepared by the reaction of the parent titanium phenoxides (1 mol) with the ligand (2 mols) and characterized by elemental analysis, molar conductance, molecular weight and i.r. spectral studies.     

Effect of niobium doping on physical, thermal, and spectral parameters of infrared transmitting BGO70 glasses

Heavy metal oxide glasses doped with 2d transition metal niobium were casted through normal melt-quench technique in the formula composition (100?x) [3Bi₂O₃–7GeO₂ (BGO70)]?xNb₂O₅ where 5 ≤ x ≤ 25. Experimentally measured values of density d _exp were 6.737–7.149 g/cc ± 0.06 %. Corresponding molar volume V _m exp had values 29.677–31.550 cc ± 0.04 %, V _pyc varied 32.28–34.71 cc ± 0.03 % and oxygen molar volume $ V_{{{\text{mO}}^{2-} }} $ increased linearly from 17.761 to 20.467 cc ± 0.06 %. Thermal coefficient of linear expansion was between 5.316 ± 0.001 × 10^?6 and 8.033 ± 0.001 × 10^?6 K^?1. Glass transition temperature T _g, onset of crystallization temperature T _x, and the stability factor ΔT were noted from DTA curves. Direct allowed energy gap E _g was between 1.809–2.988 eV and Urbach energy had value 0.32–1.49 eV. Maximum transmission efficiency was 74 % for glass BGO70-Nb10. FTIR spectra revealed that lattice vibration modes were active in 400–1,300 cm^?1 range. A modifying behavior was assigned to Nb⁵⁺ ion in the system.     

Beiträge zur Chemie der Halogensilan-Addukte. XVII. Darstellung,Kristall- und Molekülstruktur von (2, 2′ -Bipyridin)- trichloro (trichlorosiloxy)- silicium,Cl3SiOSiCl3. bipy

Contributions to the Chemistry of Halosilane Adducts. XVII. Preparation, Crystal and Molecular Structure of (2, 2′ -Bipyridine) - trichloro - (trichlorosiloxy) -silicon, Cl₃SiOSiCl₃. bipy 1 is obtained by the reaction of Cl₃SiOSiCl₃ and bipy. It crystallizes orthorhombic in the space group Pca2₁ (Z = 4). 1 contains a tetracoordinated and a hexacoordinated Si atom. The plain defined by coordinated bipy also contains the SiOSi group. The SiOSi bonding angle (152.8°) is larger than that of Cl₃SiOSiCl₃ (146°). The SiCl bonds are about 8% longer than the tetrahedral SiCl bonds. The two SiO bond lengths are different (1.684; 1.554 Å). The SiN distances (average 1.967 Å) as well as the other bond distances correspond to values found for related compounds. Configuration, SiOSi bond angle and other structural features are due to steric requirements. 1 represents the structure of least steric hindrance. The same structure is found in solution (¹H-NMR). The results confirm that sterically more demanding ligands preferentially occupy the positions vertical to the plain of bipy (phen) in octahedral bip(phen) complexes of Si, hereby minimizing steric repulsions among each other(trans positions) and by CH groups of bipy(phen) exerted on ligands in he plain of bipy(phen).     

Aspect-ratio dependent oscillatory thermocapillary convection in the floating half zone

The dependency of the critical Marangoni number on the geometrical aspect ratio of the floating half zone is essential to predict the onset of oscillatory thermocapillary convection.The experimental studies in the microgravity conditions on floating half zones of several centimeters in diameter have predicted that the critical Marangoni number increases with the increasing aspect ratio,and the terrestrial experimental studies have predicted the contradictory conclusion for floating half zones of several mil...