Application of FT-i.r. spectroscopy to the determination of COOH groups in coal

FT-i.r. studies of acid-demineralized and cation-loaded lignites demonstrate that exchange methods presently being used to determine carboxylic acid groups in coal produce systematic errors. An i.r. method based on intensity measurements of the 1710 cm^?1 carboxylic acid C = 0 stretching mode is reported.     

Determination of the kinetics of diffusion in coals by solvent swelling techniques

A simple technique has been developed for measuring the kinetics of solvent diffusion in coals at various temperatures. The technique is based on a well-known method for measuring the volumetric swelling of coals by solvents. Several coals have been examined in both pyridine and tetrahydrofuran, at temperatures between 298 and 332 K. The diffusion follows the well-established case II rate law at ambient temperatures, implying that the processes are controlled by relaxation in the coal network structure. As temperatures are increased, the process becomes more Fickian in nature. The activation energies for the diffusion-relaxation processes are in the range 31 to 82 kJ mol⁻¹.     

Molecular weight estimation by pressure during polymerization

Experimental studies for the mol wt estimation by pressure was performed with a batch polymerization of phthalic anhydride (PA) and ethylene glycol (EG). Experimental results show that the pressure in the reactor can be utilized to estimate the mol wt of products. © 1993 John Wiley & Sons, Inc.     

Coalescence and breakup of bubbles in liquids

Coalescence and breakup in a swarm of bubbles were directly observed by using the high speed cinematography. It was designed so that three dimensional motion of bubbles could be continually followed. Influence of operating conditions and liquid properties on the frequencies of bubble passing, coalescence and breakup was examined.It was seen that there was the critical distance at which the leading bubble began to exert an noticeable influence on, the following one. The distance was about 3- to 4-fold diameter of the leading bubble. Coalescence was found to take place when more than about a half of the projected area of the following bubble was overlapped with that of the leading bubble at the critical distance. On the contrary, breakup occurred in the case of the overlapping less than about a half of the projected area of the following bubble.The increment of the following bubble velocity induced by the leading one was empirically correlated with the bubble distance and the angle between the straight line joining the centers of bubbles and the vertical axis. The Reynolds numbers had no appreciable effect on the velocity increment within the range examined.     

Multi-objective Optimization Design of Magnesium Alloy Wheel Based on Topology Optimization

Lightweight of automatic vehicle is a significant application trend,using topology optimization and magnesium alloy materials is a valuable way.This article des...     

Bayesian Segmentation of Hip and Thigh Muscles in Metal Artifact-Contaminated CT Using Convolutional Neural Network-Enhanced Normalized Metal Artifact Reduction

Journal of Signal Processing Systems - In total hip arthroplasty, analysis of postoperative medical images is important to evaluate surgical outcome. Since Computed Tomography (CT) is most...     

Factors influencing methane emission from peat soils: Comparison of tropical and temperate wetlands

Methane (CH₄) emissions from peat soils in tropical and temperate wetlands were compared. Annual CH₄ emission rates in Ozegahara, the largest wetland on Honshu main island, Japan, were higher than in drained forest wetland areas examined in Indonesia. Methane emissions from the lowland paddy fields examined in Indonesia were higher than those of peaty paddy fields in Japan. There was generally a positive correlation (r² = 0.09; P < 0.1) between CH₄ emissions and CH₄ production activities in wetland soils. In Ozegahara, there was a positive relationship (r² = 0.80; P < 0.01) between CH₄ production activities and soil pH, but there was no such relationship in Indonesia. The range of soil pH in Ozegahara was 5–7, while pH values in the Indonesian sites were lower than 5. There was a positive response of CH₄ emission with respect to groundwater level in all of these areas. In Indonesia, land-use change from swamp and drained forest to cassava or coconut field lowered groundwater levels and decreased CH₄ emission, while change to lowland paddy raised the groundwater level and increased CH₄ emission. Addition of acetate generally inhibited CH₄ production during the early period (until 2 weeks) of incubation, then enhanced it afterward in both Ozegahara and Indonesian wetland soils. Addition of hydrogen mostly enhanced CH₄ production. From the results of this study, CH₄ fluxes from peat soil to the atmosphere were positively correlated with CH₄ production activities, and CH₄ production activity in peat soil was regulated by soil pH, while land-use change from wetland to upland crop lowered groundwater level and thus reduced CH₄ production and enhanced CH₄ oxidation.     

Thermal behavior of polymethacrylonitrile

The intramolecular cyclization by heating and the thermal degradation of polymethacrylonitrile samples prepared with various initiators, AIBN (A), BPO (B), BuLi (C), Et₂Mg (D), and methacrylonitrile–methacrylic acid copolymer (E), were investigated by DTA, TGA, and infrared spectroscopy. The rate of formation of ? C?N? linkages determined by IR was in the order of E > C > D > B > A. An endothermic peak of DTA thermogram due to thermal degradation was observed at approximately 345°C for the ionically initiated samples, whereas two endothermic peaks were observed at approximately 315°C and 365°C for the radically initiated ones. In the TGA thermograms, although the ionically initiated samples decomposed continuously in a single stage, the radically initiated ones showed weight loss in two steps, with an inflection point at about 330°C. The first stage of thermal degradation of radically initiated samples was concluded to be initiated at the terminal double bonds formed as a result of termination by disproportionation, and the second one at higher temperatures is initiated at random in the polymer. The ionically initiated samples without terminal double bond decompose exclusively by random scission.     

Energy-Dependent Endocytosis Is Responsible for Skin Penetration of Formulations Based on a Combination of Indomethacin Nanoparticles and l-Menthol in Rat and Göttingen Minipig

We previously designed a Carbopol gel formulation (N-IND/MEN) based on a combination of indomethacin solid nanoparticles (IND-NPs) and l-menthol, and we reported that the N-IND/MEN showed high transdermal penetration. However, the detailed mechanism for transdermal penetration of IND-NPs was not clearly defined. In this study, we investigated whether endocytosis in the skin tissue of rat and Göttingen minipig is related to the transdermal penetration of IND-NPs using pharmacological inhibitors of endocytosis. The pharmacological inhibitors used in this study are as follows: 54 µM nystatin, a caveolae-mediated endocytosis (CavME) inhibitor; 40 µM dynasore, a clathrin-mediated endocytosis (CME) inhibitor; and 2 µM rottlerin, a micropinocytosis (MP) inhibitor. The N-IND/MEN was prepared by a bead mill method, and the particle size of solid indomethacin was 79–216 nm. In both rat and Göttingen minipig skin, skin penetration of approximately 80% IND-NPs was limited by the stratum corneum (SC), although the penetration of SC was improved by the combination of l-menthol. On the other hand, the treatment of nystatin and dynasore decreased the transdermal penetration of indomethacin in rats and Göttingen minipigs treated with N-IND/MEN. Moreover, in addition to nystatin and dynasore, rottlerin attenuated the transdermal penetration of IND-NPs in the Göttingen minipigs’ skin. In conclusion, we found that l-menthol enhanced the SC penetration of IND-NPs. In addition, this study suggests that the SC-passed IND-NPs are absorbed into the skin tissue by energy-dependent endocytosis (CavME, CME, and/or MP pathways) on the epidermis under the SC, resulting in an enhancement in transdermal penetration of IND-NPs. These findings provide significant information for the design of nanomedicines in transdermal formulations.     

Preparation of Fiberlike Silicon Nitride from Diatomaceous Earth

Fiberlike Si₃N₄ was prepared by the carbothermal reduction of diatomaceous earth in a flow of nitrogen and ammonia. Diatomaceous earth, which is an inexpensive raw material, is composed of 82.5 wt% SiO₂, 5.69 wt% Al₂O₃, and a very small amount of metal oxides (K₂O, CaO, and Fe₂O₃). Two types of fiberlike Si₃N₄ were obtained, short needlelike fiber and woollike fiber with Fe droplets at 1350°C.