The paper deals with a comparative study of equilibrium and kinetics of phenol adsorption from aqueous solutions by means of commercial activated carbons and semi-cokes, differing in the nature of feedstock, production technology and structural characteristics. The main adsorption parameters are calculated with the usage of Langmuir and Dubinin–Radushkevich equations. The change in the characteristics of the structure and state of the surface of semi-coke P2 as a result of modification is estimated. It was found that phenol adsorption kinetics is described by a pseudo-second-order model. The adsorption rate constants and the coefficient of external diffusion mass transfer are calculated. It is proved that phenol extraction from aqueous solutions presents a mixed-diffusion nature, and the process rate is limited by external mass transfer for 13 min for SKD-515 and 22 min for ABG. To increase the adsorption capacity, the oxidative modification of the semi-coke P2 was carried out. Considering the economic and technological aspects, ABG semi-coke is recognized as a promising sorbent for phenol extraction from aqueous media.

Even in an era where 8-meter class telescopes are common, small telescopes are considered very valuable research facilities since they are available for rapid follow-up or long term monitoring observations. To maximize the usefulness of small telescopes in Korea, we established the SomangNet, a network of 0.4{1.0 m class optical telescopes operated by Korean institutions, in 2020. Here, we give an overview of the project, describing the current participating telescopes, its scientic scope and operation mode, and the prospects for future activities. SomangNet currently includes 10 telescopes that are located in Australia, USA, and Chile as well as in Korea. The operation of many of these telescopes currently relies on operators, and we plan to upgrade them for remote or robotic operation. The latest SomangNet science projects include monitoring and follow-up observational studies of galaxies, supernovae, active galactic nuclei, symbiotic stars, solar system objects, neutrino/gravitational-wave sources, and exoplanets.

Predicting the quality of materials after they are subjected to plasma sintering is a challenging task because of the non-linear relationships between the process variables and mechanical properties. Furthermore, the variables governing the sintering process affect the microstructure and the mechanical properties of the final product. Therefore, an artificial neural network modeling was carried out to correlate the parameters of the spark plasma sintering process with the densification and hardness values of Ti-6Al-4V alloys dispersed with nano-sized TiN particles. The relative density (%), effective density (g/cm3), and hardness (HV) were estimated as functions of sintering temperature (oC), time (min), and composition (change in % TiN). A total of 20 datasets were collected from the open literature to develop the model. The high-level accuracy in model predictions (>80%) discloses the complex relationships among the sintering process variables, product quality, and mechanical performance. Further, the effect of sintering temperature, time, and TiN percentage on the density and hardness values were quantitatively estimated with the help of the developed model.

We studied trichloroethylene (TCE) adsorption from aqueous solutions in equilibrium conditions by activated carbons (AC). They differ in raw materials, porous structure characteristics and chemical state of the surface. TCE adsorption isotherms were found to have a concave shape, which is characteristic of a sorbent—sorbate weak interaction. It can be a result from electrostatic repulsion of organic matter molecule from polar groups on carbon surface and adsorbed water molecules. The basic parameters of adsorption were calculated by the Dubinin–Radushkevich equation. We determined that for AG-OV-1 and SKD-515 in the coordinates of the Dubinin–Radushkevich equation, there are two linear plots suggesting adsorption in pores of different sizes or reorientation of adsorbate molecules on the activated carbon surface. The efficiency of TCE removal by the activated carbons was evaluated. To reduce the TCE to the maximum allowable, the lowest sorbent consumption was observed for AC with the highest values of surface area and micropore volume. However, the high cost and hydrophobicity of these adsorbents make it impractical to use them in adsorption columns with a fixed layer. We offered an adsorbent that reasonably combines extraction efficiency, ease of operation and economic feasibility.

Comparisons between bare carbon (CPs) and nitrogen-doped carbon nanoparticles (N-CPs) synthesised using hydrothermal reaction are carried out. It was found that hydrothermal reaction of citric acid yields graphene-like sheets, while the nitrogen doping using ethylenediamine resulted in amorphous polymeric ball-like hydrocarbons devoid of any aromatic rings. Although the Fourier transform infrared spectroscopy, Raman spectroscopy and nuclear magnetic resonance spectroscopy indicate the presence of carbon–carbon double bonds (C=C), and the ground states of both materials are very deep (> 7.8 eV) as measured by ultraviolet photoelectron spectroscopy. This indicates the conjugation is very short. This is supported by the fact that both materials are UV blue emitting peaking at 375 nm probably originating from C=C.

We present the analysis of KMT-2016-BLG-0212, a low flux-variation (Iflux−var ∼ 20 mag) microlensing event, which is in a high-cadence (Γ = 4hr −1) field of the three-telescope Korea Microlensing Telescope Network (KMTNet) survey. The event shows a short anomaly that is incompletely covered due to the brief visibility intervals that characterize the early microlensing season when the anomaly occurred. We show that the data are consistent with two classes of solutions, characterized respectively by low-mass brown-dwarf (q = 0.037) and sub-Neptune (q < 10−4) companions. Future high-resolution imaging should easily distinguish between these solutions.

In this study, an empirical relationship between the energy band gap of multi-walled carbon nanotubes (MWCNTs) and synthesis parameters in a chemical vapor deposition (CVD) reactor using factorial design of experiment was established. A bimetallic (Fe-Ni) catalyst supported on CaCO3 was synthesized via wet impregnation technique and used for MWCNT growth. The effects of synthesis parameters such as temperature, time, acetylene flow rate, and argon carrier gas flow rate on the MWCNTs energy gap, yield, and aspect ratio were investigated. The as-prepared supported bimetallic catalyst and the MWCNTs were characterized for their morphologies, microstructures, elemental composition, thermal profiles and surface areas by high-resolution scanning electron microscope, high resolution transmission electron microscope, energy dispersive X-ray spectroscopy, thermal gravimetry analysis and Brunauer-Emmett-Teller. A regression model was developed to establish the relationship between band gap energy, MWCNTs yield and aspect ratio. The results revealed that the optimum conditions to obtain high yield and quality MWCNTs of 159.9% were: temperature (700ºC), time (55 min), argon flow rate (230.37 mL min–1) and acetylene flow rate (150 mL min–1) respectively. The developed regression models demonstrated that the estimated values for the three response variables; energy gap, yield and aspect ratio, were 0.246 eV, 557.64 and 0.82. The regression models showed that the energy band gap, yield, and aspect ratio of the MWCNTs were largely influenced by the synthesis parameters and can be controlled in a CVD reactor.

To preserve the superior genetic resources and restore the endangered species, Somatic cell nuclear transfer (SCNT) has been used widely. In Korea, the research of dog cloning has made outstanding achievements including the production of the world`s first cloned dog. Sapsaree (Sapsalgae), the representative dog of Gyeongsan-si was designated as a Korea natural monument (No. 368). This male dog used in this study has azoospermia due to unknown cause. In this study, the aim was to confirm the cause of infertility in the cell donor dog and to evaluate the reproduction potential of dog cloning using infertile male dog by SCNT. First, to confirm the infertility of the cell donor dog, the reproductive history and the testis were evaluated. The breeding histology was not recorded in individual document. In histopathology, the Sertoli cell tumor was confirmed in biopsy of the cell donor dog after death. But, these tumors are predominantly in older dogs. Second, we produced the cloned dogs with the somatic cells of the infertile dog and the appearance was similar with the cell donor dog. Also, microsatellite analysis confirmed the genetic relationship between the cell donor and clone dogs. Third, the potential breeding capacity of the cloned dog was confirmed. In T4 assay, the normal dog (same age with cloned dogs), cell donor dog, and cloned dogs was investigated. The cell donor dog with azoospermia had very low T4 level, and cloned dogs showed higher level of T4 than normal dogs. In CASA, There was no significant difference in sperm motor ability between normal dogs and cloned dogs. As a result, cloned dogs produced by SCNT had no problem regarding the reproductive function of the testis. In AI experiment, the semen of clone dogs was used to fertilize a natural female bitch and was diagnosed pregnancy by ultrasonography. In total, 7 puppies were born by normal delivery (male: 3, female: 4). In conclusion, this study confirmed that the reproduction problem of non-genetic infertility can generate a normal descendant by SCNT. Also, the first successful research to restore infertile dogs was completed. Furthermore, SCNT would be useful for the restoration of endangered species and application of superior traits.