Modification of primary structures of hairpin ribozymes for probing active conformations

Hairpin ribozymes consist of two stem-loop domains, and these domains are assumed to interact with each other to produce the self-cleavage activity. We have studied the relationship of the tertiary structure of the hairpin ribozyme and the cleavage activity by dividing and re-joining the domains. A hairpin ribozyme (E50) was divided at the hinge region, and the main part was joined to a substrate (S1) using tri- or penta-cytidylates. These ribozymes retained the cleavage activity in the presence of the rest of the molecule, indicating that the active conformation could be maintained if the two domains interacted with each other. Based on the these results, we designed a new type of hairpin ribozyme by replacing one of the domains. To maintain the interaction of the domains, oligocytidylates were inserted at a junction. These reversely jointed ribozyme complexes showed cleavage activity that was dependent on the linker lengths. These modifications in the primary structure of the hairpin ribozyme confirm the structural requirement for the catalytic reaction and provide information for the correlation of the tertiary structure with the cleavage of the hairpin ribozyme.     

Characteristics of a Two-Phase Double-Superimposed Auxiliary Impulse Commutated Chopper

Circuit configurations, operations, characteristics, and evaluations of a two-phase auxiliary impulse commutated chopper are dealt with. The auxiliary impulse commutated chopper is composed of at least two main thyristors which alternately repeat turn on and turn off during each cycle operation. A commutating capacitor is commonly combined with the main thyristors to supply a commutating current for them in a reverse direction. A plurality of auxiliary thyristors is set for charging the capacitor in alternative polarities and selectively discharging through the main conducting thyristors. Since the first trial operation in 1968 of dc electric trains using the auxiliary impulse commutated chopper, this type of chopper cannot be disregarded for chopper electric trains.     

Enzymatic conversion of cyclic dipeptides to dehydro derivatives that inhibit cell division

The cell-free extract of an albonoursin-producing strain, Streptomyces albulus KO-23, was found to catalyze the conversion of several cyclic dipeptides having Phe and aliphatic side chain-containing amino acid residues to the corresponding dehydro derivatives. 3Z-Benzylidene-6S-methyl-2,5-piperazinedione, 3Z-benzylidene-2,5-piperazinedione, and 3Z, 6Z-dibenzylidene-2,5-piperazinedione were prepared by this conversion system. Among the dehydro cyclic dipeptides prepared, tetradehydro derivatives exhibited inhibitory activity toward the first cleavage of sea urchin embryo, while didehydro derivatives did not. We previously found that cyclo(Leu-Phe) and its didehydro derivatives did not show any inhibitory activity, in contrast to high activity in the case of albonoursin. Taken together, these findings indicate that dehydrogenation at the alpha,beta-positions of both amino acid residues in this type of cyclic dipeptide is required for the inhibitory activity.     

A model of carbon ion interactions in water using the classical trajectory Monte Carlo method

In this paper, model calculations for interactions of C(6+) of energies from 1 keV u(-1) to 1 MeV u(-1) in water are presented. The calculations were carried out using the classical trajectory Monte Carlo method, taking into account the dynamic screening of the target core. The total cross sections (TCS) for electron capture and ionisation, and the singly and doubly differential cross sections (SDCS and DDCS) for ionisation were calculated for the five potential energy levels of the water molecule. The peaks in the DDCS for the electron capture to continuum and for the binary-encounter collision were obtained for 500-keV u(-1) carbon ions. The calculated SDCS agree reasonably well with the z(2) scaled proton data for 500 keV u(-1) and 1 MeV u(-1) projectiles, but a large deviation of up to 8-folds was observed for 100-keV u(-1) projectiles. The TCS for ionisation are in agreement with the values calculated from the first born approximation (FBA) at the highest energy region investigated, but become smaller than the values from the FBA at the lower-energy region.     

Decomposition of environmentally persistent perfluorooctanoic acid in water by photochemical approaches

The decomposition of persistent and bioaccumulative perfluorooctanoic acid (PFOA) in water by UV-visible light irradiation, by H202 with UV-visible light irradiation, and by a tungstic heteropolyacid photocatalyst was examined to develop a technique to counteract stationary sources of PFOA. Direct photolysis proceeded slowly to produce CO2, F-, and short-chain perfluorocarboxylic acids. Compared to the direct photolysis, H2O2 was less effective in PFOA decomposition. On the other hand, the heteropolyacid photocatalyst led to efficient PFOA decomposition and the production of F- ions and CO2. The photocatalyst also suppressed the accumulation of short-chain perfluorocarboxylic acids in the reaction solution. PFOA in the concentrations of 0.34-3.35 mM, typical of those in wastewaters after an emulsifying process in fluoropolymer manufacture, was completely decomposed by the catalyst within 24 h of irradiation from a 200-W xenon-mercury lamp, with no accompanying catalyst degradation, permitting the catalyst to be reused in consecutive runs. Gas chromatography/mass spectrometry (GC/MS) measurements showed no trace of environmentally undesirable species such as CF4, which has a very high global-warming potential. When the (initial PFOA)/(initial catalyst) molar ratio was 10: 1, the turnover number for PFOA decomposition reached 4.33 over 24 h of irradiation.     

Sustainability assessment of cities: SDGs and GHG emissions

ABSTRACT

The United Nations’ (UN) sustainable development goals (SDGs), the core of the 2030 Agenda for Sustainable Development and the UN Paris Agreement, were adopted in 2015. Involvement of not only national governments but also all other stakeholders including local governments is important to promote sustainable development and to achieve the goals. The question arises, therefore, of what methods should be used to best implement and assess sustainability issues at a local level. In this light, a new version of Comprehensive Assessment System for Built Environment Efficiency (CASBEE), CASBEE for Cities, is introduced for assessing the sustainability of cities and communities around the world based on SDG indicators and greenhouse gas (GHG) emissions. The tool allows users to understand the sustainability of cities and communities based on quality (Q) and environmental load (L) perspectives. The sustainability assessments show that cities in developed countries tend to have good grades for Q, but bad grades for L, while cities in developing countries tend to have the opposite trend. This will assist cities and communities in both developed and developing countries to understand urgent problems and to identify effective solutions for sustainable development.     

Efficient decomposition of environmentally persistent perfluorooctanesulfonate and related fluorochemicals using zerovalent iron in subcritical water

Decomposition of perfluorooctanesulfonate (PFOS) and related chemicals in subcritical water was investigated. Although PFOS demonstrated little reactivity in pure subcritical water, addition of zerovalent metals to the reaction system enhanced the PFOS decomposition to form F-ions, with an increasing order of activity of no metal approximately equal Al < Cu < Zn < Fe. Use of iron led to the most efficient PFOS decomposition: When iron powder was added to an aqueous solution of PFOS (93-372 microM) and the mixture was heated at 350 degrees C for 6 h, PFOS concentration in the reaction solution fell below 2.2 microM (detection limit of HPLC with conductometric detection), with formation of F-ions with yields [i.e., (moles of F- formed)/(moles of fluorine content in initial PFOS) x 100] of 46.2-51.4% and without any formation of perfluorocarboxylic acids. A small amount of CHF3 was detected in the gas phase with a yield [i.e., (moles of CHF3)/(moles of carbon content in initial PFOS) x 100] of 0.7%, after the reaction of PFOS (372 microM) with iron at 350 degree C for 6 h. Spectroscopic measurements indicated that PFOS in water markedly adsorbed on the iron surface even at room temperature, and the adsorbed fluorinated species on the iron surface decomposed with rising temperature, with prominent release of F- ions to the solution phase above 250 degrees C. This method was also effective in decomposing other perfluoroalkylsulfonates bearing shorter chain (C2-C6) perfluoroalkyl groups and was successfully applied to the decomposition of PFOS contained in an antireflective coating agent used in semiconductor manufacturing.     

Effect of a dietary supplement containing glucosamine hydrochloride, chondroitin sulfate and quercetin glycosides on symptomatic knee osteoarthritis: a randomized, double-blind, placebo-controlled study

BACKGROUND: Oral glucosamine and chondroitin sulfate, alone and in combination, have been used worldwide for the treatment of osteoarthritis (OA), but their efficacy is controversial. This clinical study was aimed at investigating the potential of a dietary supplement containing glucosamine and chondroitin sulfate in combination with derivatives of quercetin, a naturally occurring flavonoid, (GCQ supplement) for knee OA care. RESULTS: A randomized, double‐blind, placebo‐controlled study was conducted in 40 Japanese subjects with symptomatic knee OA. Subjects were randomly assigned to GCQ supplement (1200 mg glucosamine hydrochloride, 60 mg chondroitin sulfate and 45 mg quercetin glycosides per day) or placebo and the treatment and follow‐up were continued for 16 weeks. The results of symptomatic efficacy assessment based on Japanese Orthopaedic Association criteria showed that scores for two of the four symptom/function subscales, as well as the aggregate scores, were significantly improved at week 16 or earlier in the GCQ group compared to the placebo group. Moreover, analyses of cartilage metabolism biomarkers showed a trend of improvement in type II collagen synthesis/degradation balance in the GCQ group during follow‐up. CONCLUSION: GCQ supplement was thought to be more effective than placebo in decreasing the intensity of knee OA‐associated clinical symptoms. Copyright © 2011 Society of Chemical Industry