Isolation and characterization of cellulose nanocrystals from jackfruit peel

In the present work, sustainable nanomaterials, cellulose, and spherical cellulose nanocrystals (SCNCs) were isolated from the non-edible parts of jackfruit (Artocarpus heterophyllus). Of the three different methods tested, sodium chlorite treatment produced the highest yield of cellulose, 20.08 ± 0.05% w/w (dry weight). Peaks observed in CP/MAS 13C NMR spectrum and FTIR frequencies revealed the presence of α-cellulose and absence of other biomass fractions like hemicellulose and lignin. XRD analysis showed a high crystallinity of 83.42%. An appearance of a sharp endothermal peak at 323 °C in DSC and decomposition patterns between 310–420 °C of TGA confirms the presence of cellulose. Further, Sulphuric acid hydrolysis was employed to produce SCNCs and examined by TEM for the morphology and by HPLC for the presence of glucose.

Time-resolved X-ray absorption spectroscopy on Al–Cu alloys – from solute copper to stable precipitates

Although binary aluminium alloys seem to be uninteresting and well known, some aspects of their precipitation sequence – especially the early stages immediately after quenching – are still not well understood. Since the Al–Cu system is the basis for many ternary and quaternary high-strength alloys with application in the aviation sector, it is important to understand this binary system in detail. This problem is here tackled by a unique combination of differential scanning calorimetry and X-ray absorption fine structure measurements, where relaxed atomic coordinates for simulation of the spectra have been obtained by ab initio calculations. Thereby, it is possible to attribute any exo- or endothermal peak to a certain type of precipitate, even though formation and dissolution regions have a large overlap in this system. This unique combination of experimental and numerical methods allows one to determine the local atomic environment around Cu atoms, thus following the formation and growth of Guinier–Preston zones, i.e. Cu platelets on {100} planes, during the precipitation process.

Physical and chemical analysis of commercial nystatin - doi: 10.4025/actascihealthsci.v35i2.12769

Nystatin (NYS) is a fermentation-produced antibiotic of the polyene group. Commercial NYS is a mixture of compounds named NIS A1, A2 and A3. Current analysis undertook physical and chemical analyses in two samples of commercial nystatin (NYS I and NYS II). Moisture (Karl Fischer), spectroscopic (IR, UV and fluorescence) and thermal analyses (TGA and DSC) were conducted. The moisture was respectively 9.2% and 8.8% for samples I and II. Absorption spectrum in the UV/VIS region had a vibronic structure with three lmax.. The mirror image rule was not complied with in the fluorimetric analysis. Spectroscopy analysis in the IV region indicated that samples showed spectra similar one to another, analogous to crystal type A. Thermal analyses by DSC provided a wide, single endothermal peak and, therefore, similarities among the samples. DTG shows that samples undergo decomposition at three phases within the temperature range under analysis. Results show that samples are impure and not polymorphic, constituted by a mixture of the compounds A1, A2 and A3.

Thermal Properties of Nanocrystalline Silver

ABSTRACTThe thermal properties of the nanocrystalline metal Ag (n-Ag), with the average grain size of 10 run, synthesized by an inert gas condensation and in situ compacting technique under different pressures of 0.2 to 1.5 GPa were studied. The thermal stable temperature for asprepared state is 373K, above which the grain growth appears at different rates. An exothermal peak and an endothermal peak occur on the DSC curves of the n-Ag. The enthalpy of both peaks are dependent upon the compacting pressure. Tht enhancement of the specific heat in going from the polycrystalline to the nanocrystalline state varies between 5.4% and 3.6% in the temperature range of 380K to 540K. The thermal diffusivity at room temperature increases with grain growth, and approaches to the corresponding value of the polycrystalline Ag.

A differential scanning calorimetric study of the thermal behaviour of bovine β-lactoglobulin at temperatures up to 160 °C

SummaryThe thermal behaviour of β-lactoglobulin was studied by differential scanning calorimetry (DSC) in the temperature range 40–160 °C. The DSC curves revealed, in addition to the usually observed denaturation peak near 80 °C, a distinct endothermal peak between 130 and 150 °C. When the pH was increased from 6·5, the area under the peak near 80 °C (denaturation heat) decreased significantly, whereas the peak area near 140 °C increased. The temperature of maximum heat absorption in the peaks near both 80 and 140 °C gradually increased as the pH decreased. Addition of sugars and variation of the heating rate both caused a temperature shift of the endothermal heat effect at 140 °C, similar to that at 80 °C. No peak near 140 °C was observed when β-mercapto-ethanol was added to the β-lactoglobulin solution before scanning. The origin and nature of the high temperature denaturation peak is discussed in terms of conformational changes of the protein.

A thermal study of thaumasite

SummaryA differential thermal analysis curve of thaumasite shows an endothermal peak at 206° C., correspinding to the loss of H2O and CO2, and a weak exothermal peak at 709° C., corresponding to recrystallization to a mixture of anhydrite and larnite, as is shown by X-ray powder photographs of material heated to 950° C. Improved powder data for thaumasite are given: the three strongest lines are at 9·66, 3·79, and 4·58 Å., and the cell-dimensions are a 10·992, c 10·311 Å.