Separation of di- and tripeptides with solvent extraction and an emulsion liquid membrane

The extraction equilibria of various di- and tripeptides with di-2-ethylhexylphosphoric acid (D2EHPA) were studied at low pH values. The complex extracted to organic phase consisted of one molecule of peptide and two molecules of D2EHPA dimer. The extraction constants of the peptides correlated well with the distribution coefficients of peptides between 1-octanol and water, which is a measure of hydrophobicity. The permeation rates of peptides through an emulsion liquid membrane were examined by using D2EHPA as a carrier, Span 80 as an emulsifier and kerosene as a diluent. The rates varied considerably with peptide type, depending upon the hydrophobicity.     

Substrate-binding lipoprotein of the cyanobacterium Synechococcus sp. strain PCC 7942 involved in the transport of nitrate and nitrite

Of the four genes (nrtABCD) required for active transport of nitrate in the cyanobacterium Synechococcus sp. strain PCC 7942, nrtBCD encode membrane components of an ATP-binding cassette transporter involved in the transport of nitrite as well as of nitrate, whereas nrtA encodes a 45-kDa cytoplasmic membrane protein, the biochemical function of which remains unclear. Characterization of the nrtA deletional mutants showed that the 45-kDa protein is essential for the functioning of the nitrate/nitrite transporter. A truncated NrtA protein lacking the N-terminal 81 amino acids, expressed in Escherichia coli cells as a histidine-tagged soluble protein, was shown to bind nitrate and nitrite with high affinity (Kd = 0.3 microM). Immunoblotting analysis using the antibody against the 45-kDa protein revealed a 48-kDa precursor of the protein, which accumulated in the cyanobacterial cells treated with globomycin, an antibiotic that specifically inhibits cleavage of the signal peptide of lipoprotein precursors. These findings indicated that the nrtA gene product is a nitrate- and nitrite-binding lipoprotein. The N-terminal sequences of putative cyanobacterial substrate-binding proteins suggested that lipoprotein modification of substrate-binding proteins of ATP-binding cassette transporters is common in cyanobacteria.     

Oxidative coupling of methane over CaO-MgO mixed oxide

Mixed oxide catalyst prepared by co-precipitating magnesium oxide and calcium oxide showed an excellent activity for the oxidative coupling of methane. The high performances were presumed to arise from the high basicity of the mixed oxide.     

Synthesis and properties of N,N'-unsymmetrical dialkyl-3,4:9,10-perylenebis(dicarboximide)s

N,N'- Unsymmetrical dialkyl-3,4:9,10-perylenebis(dicarboximide)s (in which alkyl = methyl, ethyl, propyl, butyl, isobutyl, pentyl, hexyl and octyl) were prepared by the condensation of N-alkyl-3,4:9,10-perylene-tetracarboxylic monoanhydride monoimide with the appropriate alkyl-amines. The properties of these derivatives as pigments were tested and their thermal stability measured.     

Synthesis and properties of N-alkyl-N′-aryl-3,4:9,10-perylenebis(dicarboximide)

N′-Alkyl-N′-aryl-3,4:9,10-perylenebis(dicarboximide) (alkyl = isobutyl, pentyl, hexyl, octyl, etc.; aryl = phenyl, p-tolyl, p-methoxyphenyl, etc.) were prepared by the condensation of N-alkyl-3,4:9,10-perylene-tetracarboxylic monoanhydride monoimide with arylamines (aniline, p-toluidine, p-anisidine, o-phenylenediamine, etc.). The properties of these derivatives as pigments were tested, and also the thermal stability of 3,4:9,10-perylenebis(dicarboximide) derivatives was measured.     

Ozone Generator with Cylindrical Type of Rotating Electrode

An ozone generator using a rotating electrode to improve ozone generation efficiency is proposed. The ozone generator electrode unit consists of a rotating electrode and fixed electrode. The rotating electrode has the grounded 36 pieces of tungsten wires fixed in parallel to the rotation axis on the rotating cylinder surface. A dielectric electrode is used as a fixed electrode located on the inside of the tube of the electrode unit. The width of the apparent discharge gap is 1mm. Alternating current with a frequency of 50 Hz is applied to the electrode unit. The rotation speed can be adjusted from 0 rpm to 1200 rpm by a variable speed motor. Oxygen gas is used as the material gas. Higher ozone concentration and higher ozone generation efficiency are obtained compared with that when the rotation speed is 0 rpm. The gas temperature is measured at the inlet and outlet of the ozone generator, and the rotation speed for the cooling effect is most effective at about 500 rpm. The maximum generation efficiency is estimated to be 61 g/kWh at 800 rpm, and this value is twice as large as in the case of 0 rpm.     

Clonality in hepatocellular carcinoma: analysis of methylation pattern of polymorphic X-chromosome-linked phosphoglycerate kinase gene in females

Analysis of X-chromosome inactivation patterns in women has been used to assess the clonality of various tumors. In this report, we analyzed 27 liver tumors in women, including 18 samples obtained by the performance of ultrasonically guided thin-needle biopsies. By analysis of the heterogeneity of phosphoglycerate kinase gene, 11 of 27 (41%) cases were found to be heterozygous at the gene. Of these informative 11 cases with liver tumors, 7 cases were "large" tumors (> 25 mm in diameter) and 4 cases were "small" tumors (< 25 mm in diameter). All 7 large tumors showed monoclonal patterns by the phosphoglycerate kinase gene analysis. Of the 4 small tumors, 2 showed monoclonal, and 2 showed polyclonal patterns. The 2 with monoclonal patterns were pathologically diagnosed as hepatocellular carcinoma despite their small sizes (20 mm and 23 mm). Of the two with polyclonal patterns, the smallest one (15 mm) was diagnosed as benign adenomatous hyperplasia, and the other as hepatocellular carcinoma heavily infiltrated by lymphocytes. These data suggest that analysis of the methylation pattern of the phosphoglycerate kinase gene may be helpful on rare occasions in elucidating the nature of liver tumors but must in fact be used in conjunction with histological appearances to avoid errors secondary to inflammatory infiltrates.     

The Association of Cholesterol Uptake and Synthesis with Histology and Genotype in Cortisol-Producing Adenoma (CPA)

Cortisol-producing adenoma (CPA) is composed of clear and compact cells. Clear cells are lipid abundant, and compact ones lipid poor but associated with higher production of steroid hormones. PRKACA mutation (PRKACA mt) in CPA patients was reported to be associated with more pronounced clinical manifestation of Cushing’s syndrome. In this study, we examined the association of histological features and genotypes with cholesterol uptake receptors and synthetic enzymes in 40 CPA cases, and with the quantitative results obtained by gas chromatography-mass spectrometry (GC-MS) analysis in 33 cases to explore their biological and clinical significance. Both cholesterol uptake receptors and synthetic enzymes were more abundant in compact cells. GC-MS analysis demonstrated that the percentage of compact cells was inversely correlated with the concentrations of cholesterol and cholesterol esters, and positively with the activity of cholesterol biosynthesis from cholesterol esters. In addition, hormone-sensitive lipase (HSL), which catalyzes cholesterol biosynthesis from cholesterol esters, tended to be more abundant in compact cells of PRKACA mt CPAs. These results demonstrated that both cholesterol uptake and biosynthesis were more pronounced in compact cells in CPA. In addition, more pronounced HSL expression in compact cells of PRKACA mt CPA could contribute to their more pronounced clinical manifestation.     

Non-linear current–voltage characteristics related to native defects in SrTiO3 and ZnO bicrystals

SrTiO₃ and ZnO bicrystals with various types of boundaries were fabricated in order to examine their current–voltage characteristics across single grain boundaries. Their grain boundary structures were also investigated by high-resolution transmission electron microscopy. In Nb-doped SrTiO₃, electron transport behaviors depend on the type of boundaries. Random type boundaries exhibit highly non-linear current–voltage characteristics, while low angle boundaries show a slight non-linearity. On the contrary, undoped ZnO does not exhibit non-linear current–voltage characteristics in any type of boundaries including random ones. It is suggested that the differences observed in current–voltage properties between the two systems are mainly due to the difference in the accumulation behavior of acceptor-like native defects at grain boundaries. A clear non-linearity is obtained by means of Co-doping even for the highly coherent Σ1 boundary in a ZnO bicrystal. This is considered to result from the production of acceptor-like native defects by Co-doping.     

Ferroelectric and Magnetic Properties in Room‐Temperature Multiferroic GaxFe2−xO3 Epitaxial Thin Films

GaFeO₃‐type iron oxide is a promising room‐temperature multiferroic material due to its large magnetization. To expand its usability, controlling the ferroelectric and magnetic properties is crucial. In this study, high‐quality Ga_xFe_2–xO₃ (x = 0–1) epitaxial films are fabricated and their properties are systematically investigated. All films exhibit room‐temperature out‐of‐plane ferroelectricity, showing that the coercive electric field (E_c) decreases monotonically with x. Additionally, the films show in‐plane ferrimagnetism with a Curie temperature (T_C) >350 K at x = 0–0.6. The coercive magnetic field (H_c) decreases with x at x ≤ 0.6, but shows a constant value at x > 0.6, whereas the saturated magnetization (M_s) increases with x at x ≤ 0.6, but decreases with x at x > 0.6. X‐ray magnetic circular dichroism reveals that the large magnetization at x = 0.6 is derived from Fe³⁺ (3d⁵) at octahedral sites. The controllable range of the E_c, H_c, and M_s values at room temperature (400–800 kV cm^?1, 1–8 kOe, and 0.2–0.6 µ_B/f.u.) is very wide and differs from those of well‐known multiferroic BiFeO₃. Furthermore, the Ga_xFe_2?xO₃ films exhibit room‐temperature magnetocapacitance effects, indicating that adjusting T_C near room temperature is useful to achieve large room‐temperature magnetocapacitance behavior.