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Summary  

A series of calcium silicate hydrate (C-S-H)-polymer nanocomposite (C-S-HPN) materials were prepared by incorporating poly(vinyl alcohol) (PVA) into the inorganic layers of C-S-H during precipitation of quasicrystalline C-S-H from aqueous solution. The as synthesized C-S-HPN materials were characterized by Fourier-transform infrared photoacoustic (FTIRPAS) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy/energy dispersed spectroscopy (SEM/EDS), thermogravimetric analysis (TG), differential thermogravimetry (DTG) and differential scanning calorimetry (DSC). The XRD peaks of C-S-HPN materials suggest the intermediate organizations presenting both intercalation of PVA and exfoliation of C-S-H. The SEM micrographs of C-S-H, PVA and C-S-HPN materials with different PVA contents exhibit the significant differences in their morphologies. Effects of the material compositions on the thermal stability of a series of C-S-HPN materials along with PVA and C-S-H were studied by TG, DTG and DSC. Three significant decomposition temperature ranges were observed in the TG curves of all C-S-HPN materials.

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Abstract  

A series of calcium silicate hydrate (C–S–H)-polymer nanocomposite (C–S–HPN) materials were prepared by incorporating poly(acrylic acid) (PAA) into the inorganic layers of C–S–H during precipitation of quasicrystalline C–S–H from aqueous solution. The as-synthesized C–S–HPN materials were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). The XRD analysis of C–S–HPN materials suggest the intermediate organizations presenting intercalation of PAA within C–S–H and exfoliation of C–S–H. The SEM micrographs of C–S–H, PAA and C–S–HPN materials with different PAA contents exhibit the significant differences in their morphologies. The effect of the material’s composition on the thermal stability of a series of C–S–HPN materials along with PAA and C–S–H were studied by TG, DTA and DSC. Three significant decomposition temperature ranges were observed on the TG curves of all C–S–HPN materials.

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A potential bacterial carrier for bioremediation

Characterization of insoluble potato fiber

Journal of Thermal Analysis and Calorimetry
Authors:
C. Elliott
,
Z. Ye
,
S. Mojumdar
, and
M. Saleh

Abstract  

One of the limiting factors to the effectiveness of biostimulation and bioremediation is the loss of inoculated material from the site. This can occur by a number of pathways, but is particularly problematic in open water systems where the inoculated material is simply lost in the water. It is desirable to develop new material, a matrix, within which bacteria and/or biostimulants can be incorporated. We have investigated the basic physical properties of insoluble potato starch to eventually evaluate its use as such a matrix. Insoluble starch fibers were prepared from white potato (Solanum tuberosum) and sweet potato (Ipomoea batatas) and were compared for their melting temperature by DSC and their ability to bind/aggregate bacteria. The DSC curves for white and sweet potato showed that the melting temperature is 127.34 and 133.05�C for white and sweet potato fibers, respectively. The TG curves for white and sweet potato starches exhibited one main mass loss step corresponding to the DTG peak temperature at 323.39 and 346.93�C, respectively. The two types of fibers, however, showed different binding/aggregation capacities for bacteria, with white potato approximately twice as many cells of Burkholderia cepacia (22.6 billion/g) as cells of Pseudomonas putida. The reverse was true for fibers from sweet potato, binding twice as many cells of Pseudomonas putida (23 billion/g) as cells of Burkholderia cepacia.

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Abstract

Textiles are used as thermal isolating materials for technical and clothing applications. The paper generally deals with heat transfer through textile layers by conduction, convection, radiation and evaporation of humidity. This experiment evaluates heat transfer by conduction and radiation through textile layers containing hollow polyethylene terephthalate (PET) fibres. The environment created by a composite textile layer containing hollow PET fibres and air is not identical for every method of heat transfer. During heat transfer through a textile layer, we evaluate of the importance of macromorphological structure of the elementary fibres and textile layer, taking into account the thermo-physiological properties.

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Abstract

Anthracene crystals were grown by solution growth technique by adopting slow evaporation method from the solvents CS2, CCl4 and CHCl3. The induction period was measured at various super saturations, and hence the interfacial energies were evaluated. Using the interfacial tension value, the nucleation parameters such as radius of the critical nuclei (r*), the Gibbs free energy change for the formation of a critical nucleus (ΔG*) and the number of molecules in the critical nucleus (i*) were also calculated for all these solvents at two different temperatures. The effect of surface tension, viscosity and density of these solvents are correlated with interfacial tension. The solution grown crystals were subjected to UV, FTIR, NMR and X-ray diffraction studies. The purity and high-thermal stability of the grown crystals were determined using thermal analysis.

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Abstract  

The influence of a new organic additive, chelating agent 1,10-phenanthroline (Phen) (∼5.0·10−3 M L−1) on potassium hydrogen phthalate (KHP) single crystals at 30° is investigated. The crystals were grown from the aqueous solutions of pH ∼4.5 at constant temperature by solvent evaporation technique. The chelating agent leads to an increase in metastable zone width and assists the bulk growth process. The growth rate of crystals in the presence of Phen decreases considerably with an increase in impurity concentration. Not much variation is observed in FTIR and cell parameter values, determined by XRD analysis. It appears that the growth promoting effect (GPE) of Phen is caused by the adsorption of the organic additive on the prism of KHP crystals. Differential scanning calorimetry (DSC) and TG-DTA studies reveal the purity of the sample and no decomposition is observed up to the melting point. Scanning electron microscope (SEM) photographs exhibit the effectiveness of the impurity in changing the surface morphology of KHP crystals. Contrary to expectations, Phen depresses the NLO efficiency of KHP, suggesting that the molecular alignments in the presence of Phen results in cancellation effects disturbing the non-linearity.

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Abstract

We have prepared pure and divalent vanadyl ion-doped magnesium rubidium sulfate hexahydrate crystals by using slow evaporation solution growth technique. It is interesting to observe that Vo(II) doping influences the physical properties of MRSH. Presence of Vo(II) ions in the doped specimen was confirmed by energy dispersive spectroscopy and electron paramagnetic resonance spectroscopy. FTIR studies reveal that the doping of vanadium ion has not altered the basic structure of MRSH. Scanning electron microscope studies of doped sample reveals that structure defect centers are formed in the crystals. Gradual decomposition patterns were observed for pure and doped specimens in thermogravimetry and differential thermogravimetry. The grown crystals were also characterized by powder X-ray diffraction. The second harmonic generation efficiency tested using Kurtz powder technique is not influenced by the added dopant.

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Abstract

A number of silicon-based inorganic ion exchangers were synthesized under different conditions of preparation. The original and regenerated ion exchange capacities (IECs) were determined. Thermal stability of these materials was investigated in the temperature range of 40–800 °C. The gain/loss of IEC was studied as a function of temperature. These exchangers show a higher IEC and its retention to a considerable extent at elevated temperatures when compared to that of corresponding ion exchangers which do not contain silica. The thermogravimetric curve shows greater percent mass loss in H+ form of the exchanger than in K+ form. Dehydration studies seem to throw some light on the state of water molecules present in various samples. The empirical formula and the tentative structure for stannic arseno silicate have also been proposed.

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