Hydrothermal Activities on C-Complex Asteroids Induced by Radioactivity

C-complex asteroids, rich in carbonaceous materials, are potential sources of Earth’s volatile inventories. They are spectrally dark resembling primitive carbonaceous meteorites, and thus, C-complex asteroids are thought to be potential parent bodies of carbonaceous meteorites. However, the substantial number of C-complex asteroids exhibits surface spectra with weaker hydroxyl absorption than water-rich carbonaceous meteorites. Rather, they best correspond to meteorites showing evidence for dehydration, commonly attributed to impact heating. Here, we report an old radiometric age of 4564.7 million years ago for Ca carbonates from the Jbilet Winselwan meteorite analogous to dehydrated C-complex asteroids. The carbonates are enclosed by a high-temperature polymorph of Ca sulfates, suggesting thermal metamorphism at >300°C subsequently after aqueous alteration. This old age indicates the early onset of aqueous alteration and subsequent thermal metamorphism driven by the decay of short-lived radionuclides rather than impact heating. The breakup of original asteroids internally heated by radioactivity should result in asteroid families predominantly consisting of thermally metamorphosed materials. This explains the common occurrence of dehydrated C-complex asteroids.

Pengaruh Jenis Larutan Pemasak Terhadap Kualitas Pulp Daun Pisang

The need for paper continues to increase, indicating that there is an alternative wood material that can be used as a base for making pulp. Materials that can be used are dried banana leaves which contain cellulose. The quality of the pulp can be obtained by the characteristics of the pulp produced. This study was conducted to determine the effect of the type of solvents on the pulp quality of banana leaves. The pulp has been made using delignification process with addition of 3% NaOH or 3% Na2CO3 3% and heating up to 120 minutes, at 105 °C. Pulp quality was obtained from the results of pulp analysis, cellulose content, water content, physical appearances and qualitative analysis by FTIR. From the analysis of cellulose content, water content and FTIR instruments, pulp made with 3% NaOH solution are better suited to 3% Na2CO3 where the resulting pulp has a water content of 4.96%, a smooth and fibrous texture, a rich color, and produces a cellulose hydroxyl absorption band that is stronger than the pulp made of 3% Na2CO3. However, the pulp made from 3% NaOH solution has a lower yield (56.5%) and cellulose content (26.07%) than Na2CO3 3%. Dried banana leaves can be used as an alternative in pulp making. Keywords: pulp making; banana leaves; solvents

Effect of Varying Amount of Polyethylene Glycol (PEG-600) and 3-Aminopropyltriethoxysilane on the Properties of Chitosan based Reverse Osmosis Membranes

Chitosan and polyethylene glycol (PEG-600) membranes were synthesized and crosslinked with 3-aminopropyltriethoxysilane (APTES). The main purpose of this research work is to synthesize RO membranes which can be used to provide desalinated water for drinking, industrial and agricultural purposes. Hydrogen bonding between chitosan and PEG was confirmed by displacement of the hydroxyl absorption peak at 3237 cm−1 in pure chitosan to lower values in crosslinked membranes by using FTIR. Dynamic mechanical analysis revealed that PEG lowers Tg of the modified membranes vs. pure chitosan from 128.5 °C in control to 120 °C in CS-PEG5. SEM results highlighted porous and anisotropic structure of crosslinked membranes. As the amount of PEG was increased, hydrophilicity of membranes was increased and water absorption increased up to a maximum of 67.34%. Permeation data showed that flux and salt rejection value of the modified membranes was increased up to a maximum of 80% and 40.4%, respectively. Modified films have antibacterial properties against Escherichia coli as compared to control membranes.

The Influence of Processing Conditions on the Structure of Magnetron Sputtered Hydroxyapatite Thin Films

The growing demand for functionality of implants is necessary to cater for the growing elderly population in need of repair for damaged or diseased tissues and organs. Radiofrequency magnetron sputtered crystalline hydroxyapatite thin films with preferred crystal orientation on polished titanium substrates were produced without additional substrate heating. No hydroxyl absorption bands were detected in hydroxyapatite thin films even after the addition of water vapour during the sputtering process or hydrothermal post-treatment of the films.

Studies on Mechanical and Chemical Property Changes of Environmental Degradation Polyethylene Mulching Film Immersed in Water Environment

This research studied the effects of the water environment on the mechanical, chemical and morphological changes of environmental degradation polyethylene mulching film. The mechanical characteristics of the environmental degradation polyethylene mulching film immersed in water environment or exposed in air declined. The elongation at break retention of the sample immersed in water reached minimum value for 70 days while 40 days for sample exposed in air. FTIR showed new hydroxyl absorption band appeared at 1717cm-1after exposed for 60 days. The relative intensity of absorption band of sample exposed in air is higher than sample immersed in water. AFM images showed large fluctuation on the surface after immersed in water or exposed in air for 60days.

Study on Relationship between BPA Migration and Thermal-Oxidative Aging Degree of Polycarbonate

The present work was concerned with the study on relationship between the migration level of BPA and thermal-oxidative aging degree of PC used as food and packaging materials. It was indicated that with the increasing of thermal-oxidative aging time, the migration level of BPA increased. The migration level was far beyond the GB/T5009.99-2003 (China). Variation of phenolic hydroxyl absorption intensity in IR spectra and the maximum absorption wavelength red shift of benzene in UV-Vis spectra indicated the same law; Initial weight loss temperature and maximum weight loss rate temperature of PC after thermal-oxidative aging were reduced by 1-2°C and 3-5°C respectively, and the thermal stability declined

Research of Low Rank Bituminous Coal Heat Treating and Hydrogenation Upgrading

This paper developments the research of improving the plasticity of low rank bituminous coal. The purpose is to improve the caking property of low rank bituminous coal and expand coking coal resources. The hydrothermal treatment, co-pyrolysis adding waste plastic and hydrogenation processing are chosen to process low rank bituminous coal. Several means including FTIR spectroscopy, thermogravimetric analysis, gas chromatographic(GC) and caking index are used to analyze the treated coal and generated gas products. The results show that the carboxyl groups of coal are removed after hydrothermal treatment, and the intensity of hydroxyl absorption increases. The oxygen-containing functional groups except hydroxyl groups of coal are removed after hydrogenation. The hydrogenation has obvious effects on the changes of coal structure. The reactivity and caking property of hydrotreated coal increases significantly, the indexes of coke quality of hydrotreated coal is measured to reach 16. The co-pyrolysis hydrogenation of plastic and coal results show that coal can prevent the thermal decomposition products of plastics from escaping. The caking index of hydrotreated coal with plastic is much same as that of hydrotreated coal. The addition of plastic in hydrogenation processing can not directly improve the coal plasticity.

Chemical and Physical Changes for Dimensionally Stability of Compressed Wood

The objective of this study was to determine the chemical and physical changes of chemical modified on poplar wood. The chemical modifier was impregnated into cell lumen space by pulse-dipping machine to improve the dimension stability and mechanical property of timber. The timbers were compressed and dried by the multilayer hot-press drying to produce the modified timber. The modified timber had better dimension stability than the natural wood when they were immerged water continuous eight-hour. Characteristics of Fourier Transform Infrared Spectroscopy (FTIR) for modified were studied by the FTIR spectrometer. The intensity of hydroxyl absorption peak in the infrared absorption spectrogram decreased significantly, and that of carbonyl decreased lightly, which due to the bond of the function groups of -NHCH2OH of urea-formaldehyde prepolymer react with the wood carboxyl (C=O) and hydroxyl(-OH). The morphologic models of chemical within wood were discovered by SEM.