• Geomechanics and Engineering
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• v.17 no.4
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• pp.393-403
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• 2019

The cycling impact test of red sandstone soil under different axial pressure and different impact loads are conducted to reveal the mechanical properties and energy consumption mechanism of red sandstone soil with static-dynamic coupling loading. The results show that: Under the action of different axial pressure and different impact loads, the peak stress of the specimen increases, and then tends to be stable with the times of impact. With the increase of impact times, the specific energy absorption value of the red sandstone soil specimen is increased first and then gentle development trend. When the impact loads are certain, the larger the axial pressure is, the smaller the peak value of energy absorption, which indicates that the energy utilization rate is not high under the condition of large axial pressure. Through the analysis of energy utilization, it is found that the smaller the impact load, the higher the energy utilization rate. The greater the axial pressure, the lower the energy utilization rate. when the axial pressure is large, the impact loads corresponding to the maximum values of reflectivity, transmissivity and absorptivity are the same. The relationship between reflectivity and transmissivity is negatively correlated.

• Korean Journal of Pharmacognosy
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• v.50 no.1
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• pp.18-24
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• 2019

Andrographolide, the main compound of Andrographis paniculata (A. paniculata), shows various biological properties including anti-viral, anti-inflammatory, anti-diabetic, and hepatoprotective effects. Our previous study has shown that A. paniculata extract exerts antiaging effects by activation of stemness in epidermal stem cells (EpSCs). In this study, we investigated the effect of andrographolide as a main compound of A. paniculata on EpSCs and its mechnism of action using several in vitro assays. Andrographolide increased the proliferation of EpSCs and induced cell cycle progression. Additionally, andrographolide increased VEGF production and the expression of stem cell markers integrin ${\beta}1$ and p63. Furthermore, phosphorylation levels of extracellular signal-regulated kinase 1/2 (ERK1/2), S6 ribosomal protein (S6RP) and Akt were increased by andrographolide. Taken together, these results indicate that andrographolide-induced proliferation of EpSCs is mediated by the ERK1/2, Akt-dependent pathway with increased production of VEGF and upregulated stemness through integrin ${\beta}1$ and p63.

• Journal of Yeungnam Medical Science
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• v.35 no.2
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• pp.156-164
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• 2018

Environmental contaminants are one of the important causal factors for development of various human diseases. In particular, the perinatal period is highly vulnerable to environmental toxicants and resultant dysregulation of fetal development can cause detrimental health outcomes potentially affecting life-long health. Perfluoroalkyl compounds (PFCs), emerging environmental pollutants, are man-made organic molecules, which are widely used in diverse industries and consumer products. PFCs are non-degradable and bioaccumulate in the environment. Importantly, PFCs can be found in cord blood and breast milk as well as in the general population. Due to their physicochemical properties and potential toxicity, many studies have evaluated the health effects of PFCs. This review summarizes the epidemiological and experimental studies addressing the association of PFCs with neurotoxicity and immunotoxicity. While the relationships between PFC levels and changes in neural and immune health are not yet conclusive, accumulative studies provide evidence for positive associations between PFC levels and the incidence of attention deficit hyperactivity disorder and reduced immune response to vaccination both in children and adults. In conclusion, PFCs have the potential to affect human health linked with neurological disorders and immunosuppressive responses. However, our understanding of the molecular mechanism of the effects of PFCs on human health is still in its infancy. Therefore, along with efforts to develop methods to reduce exposure to PFCs, studies on the mode of action of these chemicals are required in the near future.

• Journal of Yeungnam Medical Science
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• v.35 no.2
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• pp.213-218
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• 2018

Background: Body fats, especially both of abdominal fat pad mass and skeletal muscle fat content, are inversely related to insulin action. Therefore, methods for decreasing visceral fat mass and muscle triglyceride content may be helpful for the prevention of insulin resistance. Methods: Thalidomide, used for its anti-angiogenic and anti-inflammatory properties, was administered to rats for 4 weeks. A 10% solution of thalidomide in dimethyl sulfoxide was injected daily into the peritoneal cavity as much as 100 mg/kg of body weight. Results: The total visceral fat pad mass in the thalidomide-treated group was 11% lower than in the control group. The size of adipocytes of the epididymal fat pad mass in the thalidomide-treated group was smaller than in the control group. The intraperitoneal thalidomide treatment increased triglyceride concentrations by 16% in the red muscle, but not in the white muscle. Conclusion: The results suggested that intraperitoneal thalidomide treatment inhibited abdominal fat accumulation, and that the free fatty acids in the blood were preferentially accumulated in the red muscle rather than in the white muscle.

• Journal of Pharmacopuncture
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• v.23 no.4
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• pp.230-236
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• 2020

Objectives: Trachyspermum khasianum H. Wolff is a rare medicinal plant characteristically used by the traditional healers in traditional medicine for the treatment of throat-pain, toothache, and stomach ache. The study was designed to determine the anthelmintic and analgesic properties of the aerial parts of Trachyspermum khasianum H. Wolff (Family: Apiaceae). The aqueous and ethanol extract of T. khasianum H. Wolff was prepared and subjected for evaluation to determine the possible therapeutic effects. Methods: Anthelmintic activities of the extracts were determined by observing the time taken to paralyze and the time taken for the death of earthworms (Eisenia foetida) as compared to the standard drug-Albendazole (20 mg/ml) and control. Analgesic potential of the extracts was evaluated using Eddy's hot plate method to understand the analgesic activity in rats (Wistar rats) at 100 mg/kg and 200 mg/kg body weight doses and compared with the standard reference (Diclofenac sodium: 10 mg/kg of animals). Results: The extracts showed a significant dose-dependent anthelmintic effect at the different concentrations (10, 20, and 40) mg/ml, compared to that of the standard drug (20 mg/ml). Also, the results suggested that the plant extracts possess significantly analgesic activity in rats. Conclusion: The studies indicate that Trachyspermum khasianum shows anthelmintic and potent analgesic activities. Further research should be carried out to identify the specific phytoconstituents responsible for both analgesic and anthelmintic activities and its possible mechanism of action.

• Food Science and Industry
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• v.51 no.2
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• pp.127-135
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• 2018

The action of antioxidants was different depending on the environments where antioxidants were located. Although basic mechanisms of lipid oxidation and antioxidants were related each other, their contribution on the degree of oxidation was different. In thisreview, terminology on antioxidant properties were defined such as antioxidant activity and antioxidant capacities. In addition, antioxidant mechanisms including primary and secondary antioxidants or hydrogen donating or electron transferring antioxidants were introduced. Also, the impact of physical points of view and antioxidant polar paradox were introduced. Depending on the types of food matrice including bulk oil, oil-in-water emulsion (O/W), or solid state, antioxidant actions showed different degree and this point was explained in detail.

• Genomics & Informatics
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• v.19 no.4
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• pp.43.1-43.12
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• 2021

Campylobacter jejuni is one of the most prevalent organisms associated with foodborne illness across the globe causing campylobacteriosis and gastritis. Many proteins of C. jejuni are still unidentified. The purpose of this study was to determine the structure and function of a non-annotated hypothetical protein (HP) from C. jejuni. A number of properties like physiochemical characteristics, 3D structure, and functional annotation of the HP (accession No. CAG2129885.1) were predicted using various bioinformatics tools followed by further validation and quality assessment. Moreover, the protein-protein interactions and active site were obtained from the STRING and CASTp server, respectively. The hypothesized protein possesses various characteristics including an acidic pH, thermal stability, water solubility, and cytoplasmic distribution. While alpha-helix and random coil structures are the most prominent structural components of this protein, most of it is formed of helices and coils. Along with expected quality, the 3D model has been found to be novel. This study has identified the potential role of the HP in 2-methylcitric acid cycle and propionate catabolism. Furthermore, protein-protein interactions revealed several significant functional partners. The in-silico characterization of this protein will assist to understand its molecular mechanism of action better. The methodology of this study would also serve as the basis for additional research into proteomic and genomic data for functional potential identification.

• The Journal of Korea Robotics Society
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• v.17 no.2
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• pp.221-229
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• 2022

Sliding mode control (SMC) is a robust control method to control a robot arm with nonlinear properties. A high switching gain of SMC causes chattering problems, although the SMC allows the adequate control performance by giving high switching gain, without the exact robot model containing nonlinear and uncertainty terms. In order to solve this problem, SMC with sliding perturbation observer (SMCSPO) has been researched, where the method can reduce the chattering by compensating the perturbation, which is estimated by the observer, and then choosing a lower switching control gain of SMC. However, optimal gain tuning is necessary to get a better tracking performance and reducing a chattering. This paper proposes a method that the Q-learning automatically tunes the control gains of SMCSPO with an iterative operation. In this tuning method, the rewards of reinforcement learning (RL) are set minus tracking errors of states, and the action of RL is a change of control gain to maximize rewards whenever the iteration number of movements increases. The simple motion test for a 7-DOF robot arm was simulated in MATLAB program to prove this RL tuning algorithm. The simulation showed that this method can automatically tune the control gains for SMCSPO.

• Journal of Microbiology and Biotechnology
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• v.32 no.9
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• pp.1103-1109
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• 2022

Deoxypodophyllotoxin (DPT), a naturally occurring flavonolignan, possesses several pharmacological properties, including anticancer property. However, the mechanisms underlying DPT mode of action in oral squamous cell carcinoma (OSCC) remain unknown. This study aimed to investigate the anticancer effects of DPT on OSCC and the underlying mechanisms. Results of the MTT assay revealed that DPT significantly reduced the cell viability in a time- and dose-dependent manner. Flow cytometry analysis revealed that DPT induces apoptosis in OSCC cells in a dose-dependent manner. Moreover, DPT enhanced the production of mitochondrial reactive oxygen species (ROS) in OSCC cells. Mechanistically, DPT induced apoptosis in OSCC cells by suppressing the PI3K/AKT signaling pathway while activating the p38 MAPK signaling to regulate the expression of apoptotic proteins. Treatment with SC79, an AKT activator, reversed the effects of DPT on AKT signaling in OSCC cells. Taken together, these results provide the basis for the use of DPT in combination with conventional chemotherapy for the treatment of oral cancer.

• Steel and Composite Structures
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• v.42 no.2
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• pp.221-241
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• 2022

Perfobond rib connectors are widely used in composite structures to achieve the composite action between the steel and the concrete, and empirical expressions for their strength and secant stiffness have been obtained by numerical simulations or push-out tests. Since perfobond connections are generally in an elastic state in the service process and the structural analysis are always based on the elastic properties of the members, the secant stiffness is not applicable for the normal structural analysis. However, the tangent stiffness of perfobond connections has not been introduced in previous studies. Moreover, the perfobond connections are bearing tension and shear force simultaneously when the composite beams subjected to torque or local loads, but the current studies fail to arrive at the elastic stiffness considering the combined effects. To resolve these discrepancies, this paper investigates the initial elastic stiffness of perfobond connections under combined forces. The calculation method for the elastic stiffness of perfobond connections is analyzed, and the contributions of the perfobond rib, the perforating rebar and the concrete dowel are investigated. A finite element method was verified with a high value of correlation for the test results. Afterwards, parametric studies are carried out using the reliable finite element analysis to explore the trends of several factors. Empirical equations for predicting the initial elastic stiffness of perfobond connections are proposed by the numerical regression of the data extracted by parametric studies. The equations agree well with finite element analysis and test results, which indicates that the proposed empirical equations reflect a high accuracy for predicting the initial elastic stiffness of perfobond connections.