Intermittent Hypoxia Increased the Expression of DBH and PNMT in Neuroblastoma Cells via MicroRNA-375-Mediated Mechanism

Sleep apnea syndrome (SAS), characterized by recurrent episodes of oxygen desaturation and reoxygenation (intermittent hypoxia (IH)), is a risk factor for hypertension and insulin resistance. We report a correlation between IH and insulin resistance/diabetes. However, the reason why hypertension is induced by IH is elusive. Here, we investigated the effect of IH on the expression of catecholamine-metabolizing enzymes using an in vitro IH system. Human and mouse neuroblastoma cells (NB-1 and Neuro-2a) were exposed to IH or normoxia for 24 h. Real-time RT-PCR revealed that IH significantly increased the mRNA levels of dopamine β-hydroxylase (DBH) and phenylethanolamine N-methyltransferase (PNMT) in both NB-1 and Neuro-2a. Western blot showed that the expression of DBH and PNMT in the NB-1 cells was significantly increased by IH. Reporter assays revealed that promoter activities of DBH and PNMT were not increased by IH. The miR-375 level of IH-treated cells was significantly decreased relative to that of normoxia-treated cells. The IH-induced up-regulation of DBH and PNMT was abolished by the introduction of the miR-375 mimic, but not by the control RNA. These results indicate that IH stress increases levels of DBH and PNMT via the inhibition of miR-375-mediated mRNA degradation, potentially playing a role in the emergence of hypertension in SAS patients.     

Characterization of Silicon Carbide–Silicon Nitride Composite Ultrafine Particles Synthesized Using a CO2 Laser by Silicon-29 Magic Angle Spinning NMR and ESR

The structure of silicon carbide–silicon nitride (SiC–Si₃N₄) composite particles synthesized using a CO₂ laser was studied by magic angle spinning nuclear magnetic resonance (MAS-NMR) and electron spin resonance (ESR). The structure around Si atoms changed by introducing N. C atoms around Si were substituted by N atoms, and N-rich configurations around Si atoms increased stepwise as the N content increased. The low N content composite particles consisted of mainly SiC phase containing dissolved N. N atoms were partly present in β-SiC microcrystal and partly in the grain boundary layer in the particle. N atoms were tetrahedrally surrounded by four Si atoms in β-SiC microcrystal and were trivalent state bonded to three Si atoms in the grain boundary layer. The high N content particles consisted of SiC, Si₃N₄, and amorphous phases, whose amount depended on N content.     

Removal mechanisms for endocrine disrupting compounds (EDCs) in wastewater treatment - physical means, biodegradation, and chemical advanced oxidation: a review

Endocrine disrupting compounds (EDCs) are pollutants with estrogenic or androgenic activity at very low concentrations and are emerging as a major concern for water quality. Within the past few decades, more and more target chemicals were monitored as the source of estrogenic or androgenic activity in wastewater, and great endeavors have been done on the removal of EDCs in wastewater. This article reviewed removal of EDCs from three aspects, that is, physical means, biodegradation, and chemical advanced oxidation (CAO).     

Syntheses of group 4 transition metal complexes bearing 2-pyridinethiolate ligands and their catalytic activities for ethylene polymerization

Titanium bis(2-pyridinethiolate) complexes, Ti(6-R-SPy)₂(NMe₂)₂ (6-R-SPy = 6-R-2-pyridinethiolate, 3a: R = H; 3b: R = Me; 3c: R = Ph; 3d: R = C₆H₄-4-Me; 3e: R = C₆H₄-4-t-Bu; 3f: R = C₆H₃-3,5-Me₂), and the titanium bis(2-pyridinolate) complexes, Ti(6-Ph-OPy)₂(NMe₂)₂ (6-Ph-OPy = 6-phenyl-2-pyridinolate, 8) were prepared by treating Ti(NMe₂)₄ with 2 equiv. of 6-R-2-pyridinethiol or 6-Ph-2-pyridinol. The cis-configuration of the diamido moieties in the pseudo octahedral geometry was elucidated by X-ray crystallography for 3a. Reaction of M(NMe₂)₄ (M = Ti, Zr) with 4 equiv. of 2-pyridinethiol cleanly gave tetrakis(pyridinethiolate) complexes, M(6-H-SPy)₄·THF (6: M = Ti; 7: M = Zr). The triangular dodecahedral geometries of 6 and 7 were also revealed by X-ray crystallography. These complexes catalyzed ethylene polymerization upon activation with MAO (methylaluminoxane) or MMAO (modified MAO). The catalytic activities of titanium bis(6-aryl-pyridinethiolate) systems were found to be remarkably higher than that of titanium bis(6-methyl-pyridinethiolate) system. Among the complexes synthesized in this study, Ti[6-(C₆H₃-3,5-Me₂)-SPy]₂(NMe₂)₂ (3f)/MMAO showed the highest activity (1200 kg/Ti-mol h atm) for ethylene polymerization at 60 °C under atmospheric pressure. In contrast, the activity of the corresponding 6-aryl-pyridinolate system 8/MMAO was rather low (9.3 kg/Ti-mol h atm). Both the N-S chelating structure and the bulky aryl substituents are essential for the high activities of the 6-aryl-pyridinethiolate complexes.     

Crystallization behavior of poly(l-lactic acid)

The crystallization behavior of poly(l-lactic acid) was studied in the range of 80-160 °C. The peak crystallization time (τ_p) was defined and obtained from the crystallization isotherm measured with a differential scanning calorimeter (DSC). Isothermal crystallization temperature (T_c) dependence of log(τ_p) discretely changed at 113 °C (= T_b). The linear growth rate of spherulite, G, was measured with a polarizing microscope. The T_c dependence of G and the size of the spherulite also discretely changed at T_b. Crystal structures for samples isothermally crystallized at temperatures which were higher and lower than T_b were orthorhombic (α-form) and trigonal (β-form), respectively. The discrete change of the crystallization behavior was explained by the formation of different crystal.     

Effect of conformational changes and differences of proteins on frictional properties of poly(vinyl alcohol) hydrogel

In this study, albumin or γ-globulin, both of which are included in natural synovial fluid, was used as an additive into lubricants to investigate the ability to reduce the friction for poly(vinyl alcohol) hydrogel in mixed lubrication. It was found from a measurement in circular dichroism that albumin contains a large amount of α-helix structure and γ-globulin contains a large amount of β-sheet structure. The lubricant containing only albumin showed low friction compared to the lubricant containing only γ-globulin. The effect of protein boundary film was clarified by changing lubricant. Albumin kept the friction low after changing from γ-globulin used at initial rubbing, but γ-globulin increased the friction after changing from albumin at initial rubbing. From a sliding distance of 600 m, albumin showed lower friction but γ-globulin showed higher friction. Therefore, in the case of friction decreasing, γ-globulin forms a tight adsorbed layer and subsequently albumin forms a layer with low shearing strength. Hence, it is important to apply the adsorption layer of γ-globulin at the bottom and make a layered structure composed of albumin and γ-globulin to reduce both friction and wear.     

Magnetic measurements at pressures above 10 GPa in a miniature ceramic anvil cell for a superconducting quantum interference device magnetometer

A miniature ceramic anvil high pressure cell (mCAC) was earlier designed by us for magnetic measurements at pressures up to 7.6 GPa in a commercial superconducting quantum interference magnetometer [N. Tateiwa et al., Rev. Sci. Instrum. 82, 053906 (2011)]. Here, we describe methods to generate pressures above 10 GPa in the mCAC. The efficiency of the pressure generation is sharply improved when the Cu-Be gasket is sufficiently preindented. The maximum pressure for the 0.6 mm culet anvils is 12.6 GPa when the Cu-Be gasket is preindented from the initial thickness of 300-60 μm. The 0.5 mm culet anvils were also tested with a rhenium gasket. The maximum pressure attainable in the mCAC is about 13 GPa. The present cell was used to study YbCu(2)Si(2) which shows a pressure induced transition from the non-magnetic to magnetic phases at 8 GPa. We confirm a ferromagnetic transition from the dc magnetization measurement at high pressure. The mCAC can detect the ferromagnetic ordered state whose spontaneous magnetic moment is smaller than 1 μ(B) per unit cell. The high sensitivity for magnetic measurements in the mCAC may result from the simplicity of cell structure. The present study shows the availability of the mCAC for precise magnetic measurements at pressures above 10 GPa.     

Measurements of plastic strain around indentations caused by the impact of round and angular particles, and the origin of erosion

The aim of this paper is to examine plastic strain distributions around indentations and to consider the mechanisms of erosion damage caused by solid particle impact. A WC ball and an angular SiC particle of 3 mm in diameter were used to compare the effect of particle shape on plastic strain. Measurements of principal shearing strain distributions around the indentations were performed on surfaces of aluminum, iron and cast iron at impact angles of 20°, 30°, 40°, 60° and 90° at impact velocities from 50 to 200 m s⁻¹. It was found that the impact angle dependence was roughly consistent with the maximum principal shearing strain and erosion damage data, which have been published in previous papers and obtained during additional works in this study. The surface topography of the impact craters suggested that depth, contact area and volume of indentation are affected by the particle density and the hardness of both particle and target material. Measurements of volume ratio of lips to craters proved that material removal did not necessarily occur at a single impact of the WC ball, but occurred at the impact of the angular SiC particle at low impact angles. It is concluded that the origin of erosion is probably attributed to the conjoint actions of high plastic strains followed by subsequent removal and the cutting process caused by particle impact.     

DRYING OF CLAY AND NONCLAY MEDIA : HEAT AND MASS TRANSFER AND QUALITY ASPECTS

The researches on drying of clay and nonclay media are briefly reviewed and the role of drying in the manufacturing process is summarized. The drying process must be carefully controlled to maintain the desired product configuration. Inefficient completion of drying and poor operation of the dryer influence directly the product quality. The importance of R&D on the heat and moisture transfer phenomena, shrinkage mechanisms, deformation behavior, strain-stress relations and the internal pressure in the media during drying is stressed. Suggestions are given for further improvement of the drying process and improved design of the molding and casting processes for higher product quality     

Methanol synthesis from CO2 over Cu/ZnO catalysts prepared from various coprecipitated precursors

Various precursors of Cu/ZnO catalysts were prepared by coprecipitation methods. By varying the conditions of coprecipitation, precursors having different structures (aurichalcite, malachite, hydrozincite, or their mixture) were obtained at given Cu/Zn ratios, ranging from 30/70 to 70/30. In a wide range of the Cu/Zn ratios, the catalysts derived from the precursors containing aurichalcite exhibited high performance in the methanol synthesis from CO₂.