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Abstract

Let f: RR be integrable in a neighbourhood of xR. If there are real numbers α 0,α 2,…,α 2n−2 such that
ea
exists for some δ>0 then the limit is called the 2n-th symmetric Laplace derivative at x. There is a corresponding definition of (2n+1)-th symmetric Laplace derivative. It is shown that this derivative is a generalization of the symmetric d.l.V.P. derivative. Some properties of this derivative are studied.
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The effect of % methacrylic acid (%MAA), % neutralization (%N) and ion type (Na+ or Zn++) on the crystalline properties of neutralized ethylene-methacrylic acid copolymers (ionomers) were studied using differential scanning calorimetry (DSC). Two endothermic melting peaks were observed for all the nine ionomers studied, the lower melting point (LMP) due to ordered ionic clusters and the higher melting point (HMP) due to polyethylene crystallites. Effects of %MAA, %N and ion type on LMP and HMP for as-received, aged and annealed samples are compared. Effect of types of pretreatments on LMP and HMP of ionomers at high and low %MAA contents for both ion types are discussed. Most of these results are explained from the point of view of crystalline morphology of ionomers.

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Abstract  

Simultaneous DTA-TG is an excellent technique for evaluating phases formed in hydrothermally treated CaO-SiO2-H2O and CaO-Al2O3-SiO2-H2O systems. Thermal analysis in combination with XRD and SEM, revealed that in the CaO-Al2O3-SiO2-H2O system the amount of hydrogarnet formed was the largest when gibbsite was used as the Al source, smallest for kaolin and intermediate for metakaolin. The endotherm peak temperature of the hydrogarnet dehydration endotherm was affected by the amount of hydrogarnet and the Si content of hydrogarnet. The thermal stability and structural order of 11 Å tobermorite were reduced with the incorporation of Al and, as a result, 11 Å tobermorite transformed into 9.3 Å tobermorite at lower temperatures while the transformation of the latter into beta-wollastonite required more energy. There exists a direct relationship between the 9.3 Å tobermorite and beta-wollastonite formation temperatures. Solid-state 29Si and 27Al MAS NMR data support these findings.

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Abstract  

A method for the separation of carrier-free vanadium from scandium and bulk amount of titanium has been developed. Vanadium has been produced through the reactionnatTi(d,n)48,49V with 8 MeV deuterons from the Variable Energy Cyclotron, Calcutta. The separation is performed with Dowex 1×8, 50–100 mesh fluoride from anion exchange resin which retains all the scandium and titanium with 4.5M hydrofluoric acid as eluent, while vanadium(V) is easily eluted. The chemical yield of vanadium was >85%.

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Thermal studies have been carried out on [NiL3]X2·n H2O, whereL=1,2-propanediamine;X=Cl, Br, SCN, 1/2SO

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Interpretation of partial thermal decomposition mechanism of Dy2(SO4)3·8H2O

Thermal, electrical and spectroscopic techniques

Journal of Thermal Analysis and Calorimetry
Authors: S. Basavaraja, A. Venkataraman, and Arabinda Ray

Abstract  

Partial dehydration of Dy2(SO4)3·8H2O was studied employing TG, DSC, D.C. electrical conductivity and spectroscopic techniques. The possible mechanism for the loss of water molecules (partial dehydration) was found to be random nucleation obeying Mapel equation based on TG trace. The DSC traces are supports the results of TG traces and are also utilized to understand the enthalpy changes accompanying the partial dehydration and phase transition accompanying the dehydrated samples. D.C. electrical conductivity studies are attempted to supplement these TG studies. Attempts are made to explain the structural changes accompanying dehydration on the basis of infrared spectra and X-ray diffraction and scanning electron microscopic studies.

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Summary The strength developments of hydrothermally cured blends comprised of ordinary Portland cement (OPC) and clay-brick waste (CB) and treated at 180°C under saturated steam for 6 h were studied. Two types of CB, of different chemical and mineralogical make-up, were used to make OPC-CB blends where 10 to 80 mass% CB replaced OPC. The nature of the hydration products formed after autoclaving were subsequently investigated by using a combination of DTA, DTG, TG, X-ray diffraction, and wet chemical techniques. The modes of the hydrothermal reactions between OPC and the two types of CB, as well as the nature of the main binder belonging to the tobermorite family, are discussed and related to the development of the strength of the autoclaved articles.

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Abstract  

Fired-clay products such as bricks, tiles and pavers, are made in large volumes for use in a variety of construction applications throughout the world. A significant proportion of them ends up being a waste product either during their production process or the demolition of buildings. High pressure steam curing or autoclaving has proven extremely versatile for the manufacture of cement-based building products incorporating waste materials such as fly-ash and blast furnace slag. The nature of hydration products in an autoclaved cement based system incorporating different amounts of finely ground brick waste was investigated by means of thermal analysis and XRD, and is the subject of this paper.

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Abstract  

Nickel sulphide (NiS) was characterised using X-ray diffraction, thermal gravimetric analysis (TG) and differential scanning calorimetry (DSC). The 'as received' Millerite, stoichiometric NiS, observed to be slightly nickel deficient, was found to readily decompose in a nitrogen atmosphere at elevated temperatures (450C max.) to the sulphur deficient Godlevskite, Ni7S6. DSC and X-ray measurements demonstrated that the high temperature form of the Godlevskite was readily stabilised at room temperature. The kinetics of the α-β re-transformation in Godlevskite were then investigated using DSC and were observed to be first order.

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