Biological reduction of hexavalent chromium and mechanism analysis of detoxification by enterobacter sp. HT1 isolated from tannery effluents, Mongolia

Enterobacter sp. HT1, Cr (VI) resistant bacterial strain was isolated from the wastewater sample of the tannery in Mongolia. Batch experiments on hexavalent chromium removal was carried out at 10, 20, and 30 mg/L of Cr (VI) added as potassium dichromate (K2Cr2O7), at pH 7 and temperature of 30 °C using pure culture of Enterobacter sp. HT1 as inoculum.  The isolated HT1 is capable of reduction nearly 100% of Cr (VI) resulting in the decrease of Cr (VI) from 10 to 0.2 mg/L within 20 hours. When the concentration of Cr (VI) increased to 20 and 30mg/L, almost complete reduction of Cr (VI) could achieve after 72 and 96 hours, respectively.DOI: http://doi.dx.org/10.5564/mjc.v15i0.322 Mongolian Journal of Chemistry 15 (41), 2014, p47-5

Describing Ecological Potential and Ecological States of Rangeland to Support Livestock Management in Mongolia

Perception of rangeland degradation in Mongolia and its causes are well known but herders and policy makers lack clear messages on how much rangeland is degraded, whether is it reversible, and what management changes should be implemented. This paper illustrates a portion of our ongoing efforts to develop ESDs that can be used at the grass roots level as management tools. At the Undurshireet soum study site, which is split mainly into Gravelly, Loamy, Sandy, and Deep sandy ecological sites, rangeland community shifts in Gravelly and Loamy ecological sites are interpreted as reversible shifts in species composition or species proportion within the states, indicating that a change to grazing management may be effective for restoration of desired conditions. Sandy and Deep sandy ecological sites in this area are at high risk of erosion and may be more difficult to restore

VoIP security - attacks and solutions

Voice over IP (VoIP) technology is being extensively and rapidly deployed. Flexibility and cost efficiency are the key factors luring enterprises to transition to VoIP. Some security problems may surface with the widespread deployment of VoIP. This article presents an overview of VoIP systems and its security issues. First, we briefly describe basic VoIP architecture and its fundamental differences compared to PSTN. Next, basic VoIP protocols used for signaling and media transport, as well as defense mechanisms are described. Finally, current and potential VoIP attacks along with the approaches that have been adopted to counter the attacks are discussed

ANTIMICROBIAL AND CYTOTOXIC ACTIVITIES OF ALKALOIDS PRODUCED BY ENDOPHYTIC FUNGI

In this study, 55 endophytic fungal strains isolated from alkaloid containing plants in Mongolia were screened for their production of alkaloids. TLC analysis of ethanolic crude extracts revealed the presence of alkaloids in 5 endophytic fungal strains. The alkaloid producing strains were identified based on their morphological characteristics and/or the D1/D2 domain sequences of 28S rRNA gene. The results showed that they all belong to the genus of Fusarium. Further, total alkaloid compounds of the 5 fungal strains were isolated and examined for their antimicrobial and cytotoxic activities. As results, alkaloid compounds of SFG-S1 and 16T6-F3 strains were active against yeast and fungi, and alkaloid compounds of SFG-R3, 16Т6-F3, 14R-1 strains exhibited cytotoxic activity against HepG2 liver cancer cells

Design of a Wide Bandwidth Switchable Mirror Based on a Liquid Crystal Etalon

We propose the design for a switchable mirror with high efficiency and a 30 nm bandwidth. The device is based on a liquid crystal filled etalon. Broad bandwidth is achieved through the use of integrated half-wave layers into the dielectric stack design, while high efficiency is achieved using a polarization independent liquid crystal effect. Potential applications in the area of displays are also presented.</p

Regulation of nitrogenase by 2-oxoglutarate-reversible, direct binding of a PII-like nitrogen sensor protein to dinitrogenase

Posttranslational regulation of nitrogenase, or switch-off, in the methanogenic archaeon Methanococcus maripaludis requires both nifI(1) and nifI(2), which encode members of the PII family of nitrogen-regulatory proteins. Previous work demonstrated that nitrogenase activity in cell extracts was inhibited in the presence of NifI(1) and NifI(2), and that 2-oxoglutarate (2OG), a potential signal of nitrogen limitation, relieved this inhibition. To further explore the role of the NifI proteins in switch-off, we found proteins that interact with NifI(1) and NifI(2) and determined whether 2OG affected these interactions. Anaerobic purification of His-tagged NifI(2) resulted in copurification of NifI(1) and the dinitrogenase subunits NifD and NifK, and 2OG or a deletion mutation affecting the T-loop of NifI(2) prevented copurification of dinitrogenase but did not affect copurification of NifI(1). Similar results were obtained with His-tagged NifI(1). Gel-filtration chromatography demonstrated an interaction between purified NifI(1,2) and dinitrogenase that was inhibited by 2OG. The NifI proteins themselves formed a complex of ≈85 kDa, which appeared to further oligomerize in the presence of 2OG. NifI(1,2) inhibited activity of purified nitrogenase when present in a 1:1 molar ratio to dinitrogenase, and 2OG fully relieved this inhibition. These results suggest a model for switch-off of nitrogenase activity, where direct interaction of a NifI(1,2) complex with dinitrogenase causes inhibition, which is relieved by 2OG. The presence of nifI(1) and nifI(2) in the nif operons of all nitrogen-fixing Archaea and some anaerobic Bacteria suggests that this mode of nitrogenase regulation may operate in a wide variety of diazotrophs