Hole doping effect on ferromagnetism in Mn-doped ZnO nanowires

Tsogbadrakh, N.,Choi, E.A.,Lee, W.J.,Chang, K.J. Elsevier 2011 Current Applied Physics Vol.11 No.2

We investigate the magnetic properties of Mn-doped ZnO nanowires (NWs) using the local spin density approximation (LSDA) and the LSDA+U approach, where U represents the on-site Coulomb interaction. In carrier-free (Zn,Mn)O NWs, the majority Mn t<SUB>a</SUB> states are fully occupied, leading to an antiferromagnetic ground state. We examine the effect of additional p-type doping on the ferromagnetism by considering surface O dangling bonds, Zn vacancies, and N impurities. For all cases, localized hole carriers are generated in the majority t<SUB>a</SUB> states and promote a ferromagnetic ordering via double exchange interactions, similar to the trend of bulk (Zn,Mn)O. The ferromagnetic coupling tends to increase with increasing of the hole carrier density.

Tree canopy area-dependent changes in soil properties: a comparative study in the southern limit of boreal forest distribution

Tsogbadrakh Otgontuya,Sukhbaatar Gerelbaatar,Ganbaatar Batsaikhan,Batchuluun Burmaa,Altanjin Delgermaa,Kim Kyoung-Woong,Seah Kah Yee,Oyuntsetseg Bolormaa 한국산림과학회 2024 Forest Science And Technology Vol.20 No.1

The forest distribution in relation to mountain slope position and the relationships between forest canopy area and soil physical and chemical properties in Mongolia attract the attention of scientists. In this study, we aimed to determine (1) how the slope aspect affects the forest soil physical and chemical properties, (2) how the soil variables correlate with projected canopy area. For comparative study, we established a total of 18 (20�25m2 sized) sample plots in upper forest edge (UFE), upper slope of the forest (USF), lower slope of the forest (LSF), lower forest edge (LFE), sparse forest (SF), and degraded forest area (DFA) stand types with three replications. We measured the tree height, diameter and crown projection area of each growing tree in the sample plots, and collected soil samples for further soil physical and chemical analyses in the laboratory. Our results showed a high variation in growing stock (p<0.0001), stand density and projected canopy area (p<0.0001) in relation to mountain slope position and land-use management. We found that the slight changes in stand canopy area projection cause a high variation in soil physical and chemical properties. Among studied stand types higher means of soil temperature and bulk density and lower moisture content were observed on SF and DFA stand types. Contrary, relatively higher content of soil moisture and nutrient elements were recorded in USF, LSF, LFE. We conclude that tree canopy area becomes key determinant factor that positively influences forest soil moisture and fertility by increasing organic matter content in Mongolia.

Expression of <i>Anabaena</i> sensory rhodopsin is influenced by different codons of seven residues at the N-terminal region

Tsogbadrakh, Otgontuya,Choi, Ah Reum,Jung, Kwang-Hwan Elsevier 2018 Protein expression and purification Vol.151 No.-

<P><B>Abstract</B></P> <P>Microbial rhodopsins are well-known seven-transmembrane proteins that have been extensively studied for their structure and function. These retinal-binding proteins can be divided into two types. Type I is microbial rhodopsin, and type II (visual pigment) is expressed mostly in mammalian eyes. The two primary functions of type I rhodopsin are ion pumping activity and sensory transduction. <I>Anabaena</I> sensory rhodopsin (ASR) is a microbial rhodopsin with a specific function of photosensory transduction. ASR is expressed at moderate levels in <I>Escherichia coli</I>, but its expression level is lower compared to the general green light absorbing proteorhodopsin (GPR). In this study, full-length ASR was used to test the influence of codon usage on expression <I>E. coli</I>. Seven amino acids at the N-terminal region of ASR after the Met start codon were changed randomly using designed primers, which allowed for 8192 different nucleotide combinations. The codon changes were screened for the preferable codons that resulted in higher expression yield. Among the 57 selected mutations, 24 color-enhanced <I>E. coli</I> colonies contained ASR proteins, and they expressed ASR at a higher level than the bacteria with wild-type ASR codon usage. This result strongly suggests that the specific codon usage of only the N-terminal portion of a protein can increase the expression level of the entire protein.</P>

Biotechnological Research at the National University of Mongolia

M.Tsogbadrakh,B. Batjargal,G. Bayarmaa,D.Tumenjargal,P. Enkhbayar,N. Batkhuu 한국생물공학회 2010 한국생물공학회 학술대회 Vol.2010 No.4

Hole doping effect on ferromagnetism in Mn-doped ZnO nanowires

N. Tsogbadrakh,Eun-Ae Choi,이우진,장기주 한국물리학회 2011 Current Applied Physics Vol.11 No.2

We investigate the magnetic properties of Mn-doped ZnO nanowires (NWs) using the local spin density approximation (LSDA) and the LSDA+U approach, where U represents the on-site Coulomb interaction. In carrier-free (Zn,Mn)O NWs, the majority Mn t_a states are fully occupied, leading to an antiferromagnetic ground state. We examine the effect of additional p-type doping on the ferromagnetism by considering surface O dangling bonds, Zn vacancies, and N impurities. For all cases, localized hole carriers are generated in the majority t_a states and promote a ferromagnetic ordering via double exchange interactions,similar to the trend of bulk (Zn,Mn)O. The ferromagnetic coupling tends to increase with increasing of the hole carrier density.

Cellular Membrane Composition Requirement by Antimicrobial and Anticancer Peptide GA-K4

Mishig-Ochir, Tsogbadrakh,Gombosuren, Davaadulam,Jigjid, Altanchimeg,Tuguldur, Badamkhatan,Chuluunbaatar, Galbadrakh,Urnukhsaikhan, Enerelt,Pathak, Chinar,Lee, Bong-Jin Bentham Science Publishers 2017 Protein and peptide letters Vol.24 No.3

Online continuing medical education in Mongolia: needs assessment

Baatarpurev Baljinnyam,Tsogbadrakh Basbish,Bandi Solongo,Samdankhuu Gal-Erdene,Nyamjav Sumberzul,Badamdorj Oyungoo 한국의학교육학회 2022 Korean journal of medical education Vol.34 No.3

Purpose: Due to the shortage in the healthcare workforce, insufficient qualifications, a lack of infrastructure and limited resources in Mongolia, it is not always possible for healthcare workers in rural areas who wish to attend continuous training and retraining courses to do so. However, in order to provide high-quality care, the demand for distance learning and the upgrading of knowledge and practice of many medical topics (especially related to morbidity and mortality) are necessary for the rural population. This study aimed to assess the needs of e-learning medical education, of graduates in Mongolia.Methods: A cross-sectional research design was implemented. We collected data from 1,221 healthcare professionals (nursing professionals, physicians, midwives, and feldshers) who were randomly selected from 69 government hospitals in Mongolia. Data were collected using self-assessment questionnaires which captured the needs assessment in a survey for online continuous medical education in Mongolia. Data were analyzed using descriptive statistics and Kruskal-Wallis statistical test.Results: Ninety percent of the respondents reported that they plan on attending online continuous medical education with the most preferred specialty area being emergency medicine. Results using the Kruskal-Wallis statistical technique suggested the preferred specialty area, educational content, appropriate time schedule, available devices, and tools were statistically significant and were different between the nursing professionals, physicians, midwives, and feldshers (p<0.05).Conclusion: Findings provide important evidence for the implementation of measures and strategies which can assist healthcare professionals in low and middle-income areas/countries to constructively address their need for enhanced knowledge and practice through distance learning.

Neuroprotective Effect of Low Frequency-Pulsed Electromagnetic Fields in Ischemic Stroke

Urnukhsaikhan, Enerelt,Mishig-Ochir, Tsogbadrakh,Kim, Soo-Chan,Park, Jung-Keug,Seo, Young-Kwon Humana Press 2017 Applied biochemistry and biotechnology Vol. No.

<P>Low frequency-pulsed electromagnetic fields (LF-PEMFs) affect many biological processes; however, the fundamental mechanisms responsible for these effects remain unclear. Our study aimed to investigate the effect of LF-PEMFs on neuroprotection after ischemic stroke. C57B6 mice were exposed to LF-PEMF (F = 60 Hz, Bm = 10 mT) after photothrombotic occlusion. We measured the BDNF/TrkB/Akt signaling pathway, pro-apoptotic and pro-survival protein and gene expressions, and the expression of inflammatory mediators and performed behavioral tests in both LF-PEMF-treated and untreated ischemic stroke mice. Our results showed that LF-PEMF treatment promotes activation of the BDNF/TrkB/Akt signaling pathway. Subsequently, pro-survival proteins were significantly increased, while pro-apoptotic proteins and inflammatory mediators were decreased in ischemic stroke mice after LF-PEMF treatment. The results demonstrated that LF-PEMF exposure has a neuroprotective effect after ischemic stroke in mice during the recovery process.</P>

Antimicrobial Peptides: Their Physicochemical Properties and Therapeutic Application

강수진,이봉진,김도희,Tsogbadrakh Mishig-Ochir 대한약학회 2012 Archives of Pharmacal Research Vol.35 No.3

Antibiotic resistance has become a global public health problem, thus there is a need to develop a new class of antibiotics. Natural antimicrobial peptides have got an increasing attention as potential therapeutic agents. Antimicrobial peptides are small cationic peptides with broad antimicrobial activity. They can serve as critical defense molecules protecting the host from the invasion of bacteria. Even though they possess a different mode of action compared to traditional antibiotics, antimicrobial peptides couldn’t go into the drug markets because of problems in application such as toxicity, susceptibility to proteolysis, manufacturing cost, size, and molecular size. Nevertheless, antimicrobial peptides can be new hope in developing novel, effective and safe therapeutics without antibiotic resistance. Thus, it is necessary to discover new antimicrobial sources in nature and study their structures and physicochemical properties more in depth.

Substitution- and Strain-induced Magnetic Phase Transition in Iron Carbide

Dorj Odkhuu,N. Tsogbadrakh,A. Dulmaa,N. Otgonzul,D. Naranchimeg 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.69 No.8

Cementite-type carbides are of interest for magnetocaloric applications owing to their temperature- or pressure-induced magnetic phase transition. Here, using first-principles calculations, we investigate the magnetism and the magnetic phase transition in iron carbide (Fe3C) with the substitution of Cr atoms at Fe sites with the strain effect. The presence of Cr atoms is found to give rise to a second-order magnetic phase transition from a ferromagnetic phase for Fe3C to a nonmagnetic phase in chromium carbide (Cr3C).While the ternary Fe2CrC and Cr2FeC compounds prefer the ferrimagnetic ground state, the magnitudes of both the Fe and Cr spin moments, which are antiparallel in orientation, decrease as x increases in Fe3−xCrxC (x = 0, 1, 2, and 3). Furthermore, the fixed spin-moment calculations indicate that the magnetization of Fe3−xCrxC compounds can be delicately altered via the strain effect and that the magnetic-nonmagnetic phase transition occurs at an early stage of Cr substitution, x = 2.