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Determinations the potentials of silver nanoparticle biosynthesis by yeast strains isolated from wild berries M. Enkhmaa¹, R. Chinzorig², Ch. Ganzorig¹ J. Boldbaatar¹ ¹ Laboratory of Nanomaterial, Department of Chemical and Biological Engineering, center for Nanoscience and nanotechnology, National University of Mongolia ² e-lab, Department of Chemical and Biological Engineering, School of Engineering and Technology, National University of Mongolia The preparation of nanomaterials involves chemical, physical, and biological methods. Recently, there has been a growing interest in the eco-friendly synthesis of highly biocompatible nanoparticles for biomedical applications. Yeasts, known for releasing enzymes and metabolic products, offer a unique extracellular synthesis route for nanomaterials, promising innovative solutions in the field. In this study yeast strains were isolated from the Vaccinium vitis-idaea, Padua asiatica, and Lonicera caerulea respectively in Mongolia. The three yeast strains were selected based on the ability to utilize carbon sources. They were further identified using API 20C AUX to be yeast species Candida tropicalis, Candida norvegensis, and Kloeckera apiculate. The AgNPs produced by Candida tropicalis, Kloeckera apiculate, and Candida norvegensis at 30°C for 24 hours. The AgNPs samples were characterized using spectroscopy and the microscopic technique of UV-visible (UV-vis), Dynamic Light Scattering (DLS), and Fourier Transform Infrared (FTIR) analyses. The UV-vis spectra demonstrated a broad peak centering at 412 nm to 420 nm. The synthesized Ag NPs exhibited a uniform spherical shape and fine size, with an average size of 54.9 nm to 108.2 nm. FTIR analysis was employed to characterize and identify the potential biomolecules on the synthesized AgNPs. The broad band at 3425.9-3208.1 cm − 1 corresponds to −OH stretching. The band at 1641.5-1638.1 cm − 1 in the yeast extract is due to the C=O stretching vibration of carboxyl moieties. The low peak at 2125.6-2108.4 cm − 1 is attributed to the C=C stretching vibration. These results demonstrated that biomolecules of the yeast extract were responsible for the biosynthesis of AgNPs. The Kirby-Bauer method was used to antibacterial activities of yeast AgNPs against two pathogenic bacteria were determined. The highest antibacterial effect was observed on S.aureus with additional obvious effects on E.coli. Key words: Silver nanoparticles, Yeast, antibacterial activity
Introduction to the Center for Nanoscience and Nanotechnology J. Boldbaatar, M. Otgon-Ujin, D. Maral, O. Erdenechimeg, Ch. Ganzorig Department of Chemical and Biological Engineering, National University of Mongolia, Ulaanbaatar, Mongolia Email: ch_ganzorig@num.edu.mn Founded in 2008, the center has swiftly become a focal point for nanotechnology research and education in Mongolia. Over the years, it has undertaken a plethora of nanotechnology projects catering to both local and international communities. A significant part of the center’s mission revolves around capacity building in nanoscience. Recognizing the need for specialized knowledge and skills in the field, the center has initiated master’s programs in 2009, ensuring access to cutting edge research and training for postgraduate students. Not resting on its laurels, the center further expanded its educational outreach by introducing bachelor's programs in 2014. This expansion has enabled a continuous supply of skilled professionals trained right from the undergraduate level, strengthening the field's talent pool. In a strategic move in 2021, the center shifted its primary focus, rebranding its activities to emphasize the application of nanotechnology in the realm of natural and biological resources. This shift demonstrates the center's commitment to harnessing the potential of nanotechnology in diverse sectors. Now, the center is channeling its resources and expertise into six distinct research priorities. Foremost, a Simulation and Computation for delving into the computational aspects of nanotechnology, this priority aims to harness the power of simulations to understand and predict nanoscale phenomena. Another category of Nanomaterial is dedicated to the synthesis, characterization, and application of novel nanomaterials, which are the building blocks of nanotechnology. Moreover, an emerging field, Organic Electronics and Devices, focuses on developing electronics and devices using organic compounds, offering flexibility and potentially more sustainable production methods. Based on vast number of biological resources of Mongolia, Nanobiotechnology bridges between biology and nanotechnology, this interdisciplinary priority aims to create innovations that can revolutionize healthcare, agriculture, and more. Moreover, recognizing the importance of sustainable mining and construction, our Mining, Civil and Environmental Engineering area seeks to integrate nanotechnology for environmental protection and optimized resource utilization. Finally, going beyond pure research, Science Education and Entrepreneurship priority underscores the importance of educating the next generation and fostering a spirit of entrepreneurship in the field of science education and nanotechnology. In essence, the center continues to evolve, reflecting the dynamic nature of the nanoscience field and positioning itself at the forefront of technological and educational advancements.
We have theoretically investigated the feasibility of constructing a spintronic field-effect transistor with the active channel made of a polymer chain with the antiferromagnetic coupling oriented in the source-to-drain direction. We found two different device function regimes controlling the on-chain spin–charge carrier density by tuning the gate voltage. At higher charge carrier densities, the source–drain current linearly increases with decreasing charge carrier densities. In this regime, no polymer spin-polarized current is observed. Upon reaching a critical gate voltage, the current decreases with decreasing charge densities. It is accompanied by the formation of spin-polarized current, generated by an on-chain process, which can be related to spin–charge spatial distribution symmetry breaking caused either by an application of the source-to-drain voltage (higher spin polarization near the drain), or the breakdown of the Peierls dimerization near chain ends. Numerical simulation of the transistor characteristics suggests that the design of a polymer spintronic field-effect transistor is in principle feasible.
Magnetic CuFe2O4@GO nanocomposite was prepared using coal-derived graphene oxide and its antibacterial and sonophotocatalytic activity was studied. The physicochemical properties of the synthesized nanocomposite were evaluated using Ultraviolet–visible spectrometry, X-ray diffraction, Scanning electron microscopy, and Fourier transform infrared spectroscopy. The nanocomposite was demonstrated as an effective sonophotocatalyst for methyl orange degradation, and it presented antibacterial properties when tested on Gram-negative P. aeruginosa and Gram-positive S. aureus bacteria.
Future generations of electronic products will be enabled by flexible electronic circuits, displays, and sensors based on organic active materials, which could eventually reach the mainstream electronics industry. One of such devices is the organic field-effect transistor (OFET), which are three-terminal devices that are comprised of a gate, source, and drain electrode. In this study, we fabricated a bottom-gate bottom-contact OFET device using copper phthalocyanine (CuPc) as a semiconducting layer. CuPc is a commercially available metal complex, a known p-type semiconducting material. Au/Ti electrode is sputtered on Al gated silicon substrate with thermally grown SiO2 dielectric layer. CuPc films were then deposited over the substrate with patterned electrodes by physical vapor deposition at a rate of 0.35 nm/s, recorded by a quartz crystal microbalance at room temperature under a background pressure of 1.21x10-3 Pa. A thin layer of organic material was also deposited on glass slides and the optical properties of films with different thicknesses were determined by UV-Vis spectrometry and the optical band-gap energy was determined to be 1.64±0.01 eV. The thermal annealing effect on thin-film crystallization morphology was studied with atomic force microscopy (AFM) and contact angle measurement.
In this study, increasing the work function of ITO (Indium Tin Oxide) electrode while reducing that of Al cathode was examined to successfully improve the Voc (Open Circuit Voltage) values of the of Organic PV (Photovoltaic) cells. For MIM (Metal Insulator Metal) type organic PV cells, the Vbi (Built in Potential) results from the Δφ (Work Function Difference) between the anode and cathode electrodes. Using high work function values for the ITOs used as an anode, an improvement in Vbi resulting from Δφ would be expected with organic PV cells. In the cells with Al cathode (named as bilayer cell), a slight increase in PCE from 0.13 % in the case as-cleaned ITO to 0.46 % in the case ITO modified with NO2– terminal group was observed. The FF value for the devices with variously configured ultra-thin layer such as BCP/Al, BCP/C6H5COOLi/Al, Alq3/Al, and Alq3/C6H5COOLi/Al is still larger (1.3 times increased) than those of the other devices with Al and C6H5COOLi/Al cathode electrodes. Introduction
Монгол орны замын эвдрэлээс нь хамааруулан бүсчилсэн 2 байрлалаас замын суурийн үе болон шинээр зам тавихад ашиглаж буй дахин боловсруулсан хольцын химийн болон эрдсийн бүтэц найрлагыг харьцуулан судлав.
Органик электролюминесцент (EL) төхөөрөмжийн судалгаа хөгжүүлэлт болон үйлдвэрлэлийн явцад тулгарч байдаг томоохон асуудлуудын нэг болох ажиллах ашиглалтын хугацаа болон тогтворжилтыг бууруулдаг гол хүчин зүйл нь деградацийн процесс, түүний үүсэх механизмыг судлах явдал байдаг. Деградацийг бууруулах, дагалдах процессуудыг зогсоох зэрэг судалгааны ажлууд хийгдсээр байгаа хэдий ч одоогоор энэ асуудлыг бүрэн шийдвэрлэж чадаагүй байна. Иймд энэхүү судалгааны ажлаар индий-цагаан тугалгын оксид (ITO), N,N’-дифенил-N,N’-бис(3-метилфенил)-[1,1’-дифенил]-4,4’-диамин (TPD), хөнгөн цагааны трис(8-гидроксихинолин) (Alq3) болон металл Al электрод ашиглан донор/акцептор бүхий давхар үелсэн нимгэн үеийг вакуумд ууршуулан суулгах аргаар ITO(150 нм)//TPD(50 нм)/Alq3(50 нм)/Al(~100 нм) гэсэн бүтэцтэй органик EL төхөөрөмж гарган авсан. Уг төхөөрөмжийн металл электрод болон органик нимгэн үеийн гадаргууд явагдах деградацийн процессыг орчны чийгшил (~80%) болон температур (өрөөний, 80°С, 120°С)-аас хамааруулан хэмжсэн. Атомын хүчний микроскоп (AFM)-ийн аргыг ашиглан органик нимгэн үед үүсэх морфологийн өөрчлөлт, кристаллжих процессын судалгааг хийж гүйцэтгэсэн. Судалгаанд ашиглагдсан органик EL төхөөрөмжийг тогтмол хүчдэлээр ачаалж үйлчлэхэд металл Al электродын гадаргууд бөмбөлөг хэлбэртэй бүтэц (өөрөөр хэлбэл, катодын салалтын процесс) ажиглагдсан бөгөөд мөн давхар үелсэн органик нимгэн үеийн гадаргуу болон гүнд гэрэл үл цацруулагч хар толбо буюу нүх (dark spot) үүсэж деградацийн процессын AFM судалгааг хийж гүйцэтгэсэн болно.
Superhydrophobic SiO2 nanoparticle ultra-thin film was fabricated on the surface of cashmere fabric via dip coating method utilizing acetic acid and acidic water. The as-obtained cashmere fabric was characterized by SEM and FTIR analysis, and wetting behavior was determined with contact angle measurement. The stain resistance, pilling and colorfastness grade were also evaluated. Contact angle measurement revealed that cashmere fabric attained a superhydrophobic behavior with a contact angle greater than 150°. The silica nanoparticles were grafted onto surface of cashmere fabric successfully as indicated by the FTIR measurement. Colorfastness and pilling grade were improved in the surface coated cashmere; therefore, the coating process did not impose the adverse effects on the quality of the cashmere fabrics.
We present a model of the charge transport in thin film organic field-effect transistors with the active channel made of linear conjugated chains stacked on the substrate with end-on-orientation. The transport was simulated in a box consisting of 25 polymer chains, in which the delocalized quantum orbital eigenstates of the on-chain hole distribution were calculated. The inter-chain charge transfer was solved semi-classically. The full self-consistent distribution of charge density and electric field was determined for various applied gate and source–drain voltages. We found that the dependence of charge mobility on gate voltage is not monotonic: it first increases with increasing gate voltage for a limited interval of the latter, otherwise it decreases with the gate voltage. Next, we found formation of the second resonant peak for higher gate voltages. The mobility dependence on the gate voltage confirmed that the current flowing through the active semiconductor layer should be described not only as the hole transfer between adjacent repeat units of the neighbouring chains, but also as the transfer of coherences among on-chain repeat units. The presented model can also give a new insight into the charge transport in organic field-effect transistors with a novel vertical architecture.
