Carbon dioxide fixation by microalgae photosynthesis using actual flue gas discharged from a boiler

To mitigate CO₂ discharged from thermal power plants, studies on CO₂ fixation by the photosynthesis of microalgae using actual exhaust gas have been carried out. The results are as follows.

Application of europium(III) extraction with organophosphinic acid to liquid membrane transport

The extraction behavior of Eu(III) has been studied using di(2,4,4-trimethylpentyl)phosphinic acid (DTMPPA, HA) in kerosene. Europium was extracted as Eu(HA₂)₃ with the extraction constant of 2.0·10^–3. This extraction system was applied to the transport of Eu(III) across a DTMPPA liquid membrane supported on porous polytetrafluoroethylene. Europium was quantitatively moved through the liquid membrane containing 0.1M (HA)₂ as a mobile carrier from the feed solution of pH above 3 into the product solution of 0.1M HNO₃, yielding a concentration factor of ten. The transport rate increased with increasing pH and DTMPPA concentration.     

Mechanism of antioxidant action of pueraria glycoside (PG)-1 (an isoflavonoid) and mangiferin (a xanthonoid).

The antioxidant activities of pueraria glycoside (PG)-1 (isoflavonoid) and mangiferin (xanthonoid) were studied and compared with PG-3 and daidzein (isoflavonoids) and with wogonin (flavonoid). PG-1 and mangiferin rapidly scavenged 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, and inhibited lipid peroxidation which was initiated enzymatically by reduced nicotinamide adenine dinucleotide phosphate (NADPH) or non-enzymatically by ascorbic acid or Fenton's reagent (H2O2 + Fe2+) in rat liver microsomes. Wogonin inhibited the enzymatically induced lipid peroxidation but had no scavenging effect on DPPH radical or on the non-enzymatic peroxidation. PG-3 and daidzein did not show any of these effects. Formation of Fe2+ by NADPH-dependent cytochrome P-450 reductase was inhibited by wogonin, but not by PG-1 or mangiferin. PG-1 and mangiferin had no effect on terminating radical chain reaction during the lipid peroxidation in the enzymatic system of microsomes or in the linoleic acid hydroperoxide-induced peroxidation system. These results suggest that PG-1 and mangiferin have an antioxidant activity, probably due to their ability to scavenge free radicals involved in initiation of lipid peroxidation. In contrast, wogonin may affect NADPH-dependent cytochrome P-450 reductase action, since it inhibited only the enzymatically induced lipid peroxidation.     

Pre-fibrillation of pulps to manufacture cellulose nanofiber-reinforced high-density polyethylene using the dry pulp direct kneading method

The dry pulp direct kneading method is an industrially viable, low-energy process for manufacturing cellulose nanofiber (CNF)-reinforced polymer composites, where the chemically modified pulps are nanofibrillated and uniformly dispersed in the polymer matrix during melt compounding. In the present study, cellulose fibers of various sizes ranging from surface-fibrillated pulps (20 μm in width) to fine CNFs (20 nm in width) were prepared from softwood bleached kraft pulps using a refiner and a high-pressure homogenizer. These cellulose fibers were modified with alkenyl succinic anhydride and dried. The dried fibers were used as a feed material for melt compounding in the dry pulp direct kneading method to fabricate CNF-reinforced high-density polyethylene (HDPE). When surface-fibrillated pulps were employed as a feed material, the pulps were nanofibrillated and dispersed uniformly in the HDPE matrix during melt compounding. The resulting composites had much better properties—i.e., much higher tensile modulus and strength values, and much lower coefficient of thermal expansion values—than the composites produced using pulps without pre-fibrillation. However, when CNFs were used as a feed material, they were shortened and agglomerated during melt compounding, and the properties of the composites consequently deteriorated. The study concludes that surface-fibrillated pulp, which can be produced cost-effectively using a refiner on an industrial scale, is more suitable as a feed material than CNFs for melt compounding in the dry pulp direct kneading method. This finding enables the elimination of a preliminary step in the preparation of CNFs from pulps, which is a time-consuming and energy-intensive process.

Graphical abstract

     

Studies on pyrazines. 4.. The synthesis of 2-hydroxy-6-phenylpyrazine and its derivatives

This report describes a new method for the preparation of 2-hydroxy-6-phenylpyrazine ( 1 ). Amino acetal 5 was converted to glycyl amino acetal 7 by two steps in excellent yield. Cycliza-tion of 7 to 1 was accomplished in 33% yield by refluxing in acetic acid followed by oxidation with manganese dioxide. Compound 1 was also prepared by hydrolysis of amino- and methoxy-pyrazines 3 and 15 , derived from 2-hydroxy-5-phenylpyrazine ( 2 ) and the 2-amino homologue 4 , respectively, and by decarboxylation of 2-hydroxy-5-phenylpyrazinecarboxylic acid ( 19 ).     

Blue myoglobin reconstituted with an iron porphycene shows extremely high oxygen affinity

Myoglobin will be a good scaffold for engineering a function into proteins. To modulate the physiological function of myoglobin, almost all approaches have been demonstrated by site-directed mutagenesis, however, there are few studies which show a significant improvement in the function. In contrast, we focused on the replacement of heme in the protein with an artificial prosthetic group. Recently, we prepared a novel myoglobin reconstituted with an iron porphycene as a structural isomer of mesoheme. The bluish colored reconstituted myoglobin is relatively stable and the deoxymyoglobin reversibly binds ligands. Interestingly, the O2 affinity of the reconstituted myoglobin, 1.1 x 109 M-1, is a significant 1,400-fold higher than that of the native myoglobin. Furthermore, the unfavorable autoxidation kinetics show 7-fold decrease in rate for the reconstituted myoglobin relative to the native myoglobin, indicating the stable oxy-form against autoxidation. The net results come from the slow dissociation of the O2 ligand in the reconstituted myoglobin, koff = 0.11 s-1, because of the formation of strong hydrogen bond between His64 and negatively charged dioxygen. The present study indicates that the replacement of native heme with an artificially created prosthetic group will give us a unique function into a hemoprotein.     

Proteomic LC-MS systems using nanoscale liquid chromatography with tandem mass spectrometry

Current nano-scale liquid chromatography-tandem mass spectrometry (nanoLC-MS/MS) approaches in proteome research are reviewed from an analytical perspective. For comprehensive analysis of cellular proteins, analytical methods with higher resolution, sensitivity, and wider dynamic range are required. Miniaturized LC coupled with tandem mass spectrometry is currently one of the most versatile techniques. In this review, the current status of nanoLC-MS/MS systems as well as data management systems is addressed. In addition, the future prospects for complete proteomics are discussed.     

A study of molecular vibrational relaxation mechanism in condensed phase based upon mixed quantum-classical molecular dynamics. II. Noncollisional mechanism for the relaxation of a polar solute in supercritical water

Mixed quantum-classical molecular dynamics method has been applied to vibrational relaxation of a hydrophilic model NO in supercritical water at various densities along an isotherm above the critical temperature. The relaxation rate was determined based on Fermi's golden rule at each state point and showed an inverse S-shaped curve as a function of bulk density. The hydration number was also calculated as a function of bulk density based on the calculated radial distribution function, which showed a good correlation with the relaxation rate. Change of the survival probability of the solute vibrational state was analyzed as a function of time together with the trajectory of the solvent water and the interaction with it. We will show that the solvent molecule resides near the solute molecule for a while and the solvent contributes to the relaxation by the random-noiselike Coulombic interaction only when it stays near the solute. After the solvent leaves the solute, it shows no contribution to the relaxation. The relaxation mechanism for this system is significantly different from the collisional one found for a nonpolar solute in nonpolar solvent in Paper I. Then, the relaxation rate is determined, on average, by the hydration number or local density of the solvent. Thus, the density dependence of the relaxation rate for the polar solute in supercritical water is apparently similar to that found for the nonpolar solute in nonpolar solvent, although the molecular process is quite different from each other.     

Light emission from chlorine atoms formed in the dissociative excitation of HCI in a flowing afterglow of discharged argon

Light emission from Cl(5p) atoms (near 440 nm) produced in the reaction of HCl in a discharged flow of argon was investigated with a flowing-afterglow apparatus. Ionic species, most probably argon ions in metastable states, Ar^+M, were found to be responsible for the Cl(5p) production in the dissociative excitation of HCl.     

Hydrides with the perovskite structure: General bonding and stability considerations and the new representative CaNiH3

The stability and electronic structure of perovskite hydrides ABH₃ were investigated by means of first-principles density functional calculations. Two types of perovskite hydrides are distinguished: (1) When A and B are alkali and alkaline earth metals, the hydrides are ionic compounds with calculated band gaps of around 2 eV and higher. Their stability trend follows basically the concept of Goldschmidt's tolerance factor. (2) When A is one of the heavier alkaline earth metals (Ca, Sr, Ba) and B a transition metal, stable compounds ABH₃ result only when B is from the Fe, Co, or Ni groups. This stability trend is basically determined by effects associated with d band filling of both the transition metal and the hydride. In contrast to group (1) perovskites, the transition metal-containing compounds are metals. The synthesis of CaNiH₃ and its structure determination from CaNiD₃ is reported. This compound is a type (2) perovskite hydride with a fully occupied hydrogen position (CaNiD₃: a=3.551(4) Å, d_Ni-D=1.776(2) Å). Its stability is discussed with respect to transition metal hydrides with complex anions (e.g., Mg₂NiH₄, Na₂PdH₂, Sr₂PdH₄).