Human and bacterial oxidative demethylases repair alkylation damage in both RNA and DNA

Repair of DNA damage is essential for maintaining genome integrity, and repair deficiencies in mammals are associated with cancer, neurological disease and developmental defects. Alkylation damage in DNA is repaired by at least three different mechanisms, including damage reversal by oxidative demethylation of 1-methyladenine and 3-methylcytosine by Escherichia coli AlkB. By contrast, little is known about consequences and cellular handling of alkylation damage to RNA. Here we show that two human AlkB homologues, hABH2 and hABH3, also are oxidative DNA demethylases and that AlkB and hABH3, but not hABH2, also repair RNA. Whereas AlkB and hABH3 prefer single-stranded nucleic acids, hABH2 acts more efficiently on double-stranded DNA. In addition, AlkB and hABH3 expressed in E. coli reactivate methylated RNA bacteriophage MS2 in vivo, illustrating the biological relevance of this repair activity and establishing RNA repair as a potentially important defence mechanism in living cells. The different catalytic properties and the different subnuclear localization patterns shown by the human homologues indicate that hABH2 and hABH3 have distinct roles in the cellular response to alkylation damage.     

Robust Control of Robotic Manipulators in the Task-Space Using an Adaptive Observer Based on Chebyshev Polynomials

In this paper, an adaptive observer for robust control of robotic manipulators is proposed.The lumped uncertainty is estimated using Chebyshev polynomials. Usually, the uncertainty upper bound is required in designing observer-controller structures. However, obtaining this bound is a challenging task. To solve this problem, many uncertainty estimation techniques have been proposed in the literature based on neuro-fuzzy systems. As an alternative, in this paper, Chebyshev polynomials have been applied to uncertainty estimation due to their simpler structure and less computational load.Based on strictly-positive-real(SPR) Lyapunov theory, the stability of the closed-loop system can be verified. The Chebyshev coefficients are tuned based on the adaptation rules obtained in the stability analysis. Also, to compensate the truncation error of the Chebyshev polynomials, a continuous robust control term is designed while in previous related works, usually a discontinuous term is used. An SCARA manipulator actuated by permanent magnet DC motors is used for computer simulations.Simulation results reveal the superiority of the designed method.     

伊朗北部GoLestan省的食虫虻种类（双翅目：短角亚目：食虫虻总科：食虫虻科）

本文记述了伊朗北部GoLestan省的食虫虻种类（双翅目：食虫虻科），总计调查鉴定了食虫虻科的10亚科（ ApocLeinae，AsiLinae，Dasypogoninae，BrachyrhopaLinae，Laphriinae，Laphystiinae，Leptogastrinae，Brachyrho-paLinae，Stenopogoninae和Stichopogoninae）17属21种。     

Structure of HIV-1 gp120 V1/V2 domain with broadly neutralizing antibody PG9

Variable regions 1 and 2 (V1/V2) of human immunodeficiency virus-1 (HIV-1) gp120 envelope glycoprotein are critical for viral evasion of antibody neutralization, and are themselves protected by extraordinary sequence diversity and N-linked glycosylation. Human antibodies such as PG9 nonetheless engage V1/V2 and neutralize 80% of HIV-1 isolates. Here we report the structure of V1/V2 in complex with PG9. V1/V2 forms a four-stranded β-sheet domain, in which sequence diversity and glycosylation are largely segregated to strand-connecting loops. PG9 recognition involves electrostatic, sequence-independent and glycan interactions: the latter account for over half the interactive surface but are of sufficiently weak affinity to avoid autoreactivity. The structures of V1/V2-directed antibodies CH04 and PGT145 indicate that they share a common mode of glycan penetration by extended anionic loops. In addition to structurally defining V1/V2, the results thus identify a paradigm of antibody recognition for highly glycosylated antigens, which-with PG9-involves a site of vulnerability comprising just two glycans and a strand.     

Influence of the roughness and shape of quartz particles on their flotation kinetics

Surface roughness and shape play an important role on the behavior of particles in various processes such as flotation. In this research, the influence of different grinding methods on the surface roughness and shape characteristics of quartz particles as well as the effect of these parameters on the flotation of the particles was investigated. The surface roughness of the particles was determined by measuring their specific surface area via the gas adsorption method. The shape characteristics of the particles were measured and calculated by images obtained by scanning electron microscopy via an image analysis system. The flotation kinetics was determined using a laboratory flotation cell. The results showed that the particles of rod mill products have higher roughness and elongation ratio and lower roundness than the particles of ball mill products. The flotation kinetics constant of the particles increased with their surface roughness increasing. Particles with higher elongation and lower roundness indicated higher floatability. In addition, the influence of the surface roughness on the flotation kinetics was greater than that of shape parameters.     

Molybdenite alkali fusion and leaching: reactions and mechanism

The production of MoO₃ from Sarcheshmeh molybdenite concentrate via a pyro-hydrometallurgical process was studied. The molybdenite concentrate and sodium carbonate were premixed and fused under air atmosphere. Then the fused products were leached in water and the dissolved molybdenum was recovered as ammonium molybdate. The ammonium molybdate was then calcined to produce molybdic oxide. At the fusion stage, the effect of the mass ratio of carbonate to sulfide on the reaction products and the solubility of the products was investigated. The results show that during the fusion, sodium molybdate and sodium sulfate are the final reaction products and sodium sulfide is detected as an intermediate reaction product. By melting at 850℃ with 5wt% excess carbonate, the maximum solubility of the products is obtained. The molybdenum is recovered from the solutions as ammonium molybdate.