1,722,296 research outputs found
Systems metabolic engineering
No full textAs our concerns on environmental problems are increasing, there has been much interest in developing bio-based systems for the production of chemicals, fuels, and materials from renewable resources. Microorganisms isolated from nature are often employed for this purpose, but their efficiencies of producing desired products are rather low. Thus, their phenotypes have been improved by random mutagenesis and selection. During the last couple of decades, metabolic engineering has been established and applied for more efficient and rational design and development of microbial strains producing these products. We are now observing another paradigm shift in developing industrial microorganisms based on the recent advances in systems biology and synthetic biology, which are enabling us to approach biological and biotechnological problems at systems level with designer’s concept. It is now becoming possible to perform systems metabolic engineering. In this lecture, I will present the general strategies for systems metabolic engineering with several example products such as amino acids, diamines, and biopolymers
Celecoxib and sulindac sulfide elicit anticancer effects on PIK3CA-mutated head and neck cancer cells through endoplasmic reticulum stress, reactive oxygen species, and mitochondrial dysfunction
No full textGain-of-function mutation in the phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) catalytic subunit alpha gene (PIK3CA) is a significant factor in head and neck cancer (HNC). Patients with HNC harboring PIK3CA mutations receive therapeutic benefits from the use of non-steroidal anti-inflammatory drugs (NSAIDs). However, the molecular mechanisms underlying these effects remain unknown. Here, we examined the Detroit562 and FaDu cell lines as HNC models with and without a hyperactive PIK3CA mutation (H1047R), respectively, regarding their possible distinct responses to the NSAIDs celecoxib and sulindac sulfide (SUS). Detroit562 cells exhibited relatively high PI3K/Akt pathway-dependent cyclooxygenase-2 (COX-2) expression, associated with cell proliferation. Celecoxib treatment restricted cell proliferation and upregulated endoplasmic reticulum (ER) stress-related markers, including GRP78, C/EBP-homologous protein, activating transcription factor 4, death receptor 5, and reactive oxygen species (ROS). These effects were much stronger in Detroit562 cells than in FaDu cells and were largely COX-2-independent. SUS treatment yielded similar results. Salubrinal (an ER stress inhibitor) and N-acetyl-L-cysteine (a ROS scavenger) prevented NSAID-induced ROS generation and ER stress, respectively, indicating crosstalk between ER and oxidative stress. In addition, celecoxib and/or SUS elevated cleaved caspase-3 levels, Bcl-2-associated X protein/Bcl-2-interacting mediator of cell death expression, and mitochondrial damage, which was more pronounced in Detroit562 than in FaDu cells. Salubrinal and N-acetyl-L-cysteine attenuated celecoxib-induced mitochondrial dysfunction. Collectively, our results suggest that celecoxib and SUS efficiently suppress activating PIK3CA mutation-harboring HNC progression by inducing ER and oxidative stress and mitochondrial dysfunction, leading to apoptotic cell death, further supporting NSAID treatment as a useful strategy for oncogenic PIK3CA-mutated HNC therapy
Geometric snakes for triangular meshes
No full textFeature detection is important in various mesh processing techniques, such as mesh editing, mesh morphing, mesh compression, and mesh signal processing. In spite of much research in computer vision, automatic feature detection even for images still remains a difficult problem. To avoid this dfficulty, semi-automatic or interactive techniques for image feature detection have been investigated. In this paper, we propose a geometric snake as an interactive tool for feature detection on a 3D triangular mesh. A geometric snake is an extension of an image snake, which is an active contour model that slithers from its initial position specified by the user to a nearby feature while minimizing an energy functional. To constrain the movement of a geometric snake onto the surface of a mesh, we use the parameterization of the surrounding region of a geometric snake. Although the definition of a feature may vary among applications, we use the normal changes of faces to detect features on a mesh. Experimental results demonstrate that geometric snakes can successfully capture nearby features from user-specified initial positions.X1146sciescopu
Why do some Korean parents hesitate to vaccinate their children?
Full text linkOBJECTIVES: Vaccinations for infectious diseases are opposed despite their achievement, and this opposition has recently been revealed in Korea. However, research in Korea has not been vigorous. The authors studied why some Korean parents hesitate to vaccinate their children by applying the health belief model.
METHODS: Parents who hesitate to vaccinate and parents who do not were surveyed in alternative education preschools and elementary schools. They were classified into four types of hesitancy and statistically compared.
RESULTS: Among the 129 subjects, 43 vaccinated without hesitancy, 20 vaccinated on time with hesitancy, 32 vaccinated with a deliberate delay of one month or longer, and 34 did not vaccinate. Vaccination increased with an increase in the awareness that severe outcomes can occur when unvaccinated. Concerns about adverse reactions from vaccinations or direct/indirect experiences affected refusal. Furthermore, perceptions of the lack of meaningfulness of vaccinations, distrust of policy and safety management, influence of leaders or activists in joined organizations, and experts of Korean traditional or alternative medicine affected refusal. Explanations by doctors, text messages and mails from institutions, and concerns about disadvantages caused by not complying with government policies increased vaccination.
CONCLUSIONS: The reasons for vaccine hesitancy and acceptance were similar to the results of international research. Health authorities and professionals should communicate sufficiently and appropriately with hesitant parents and find ways to rationally resolve social conflicts. However, this sample was small and there is little Korean research, so more in-depth and diverse researchs are needed
Public perception of the appropriateness of COVID-19 management strategies and level of disturbances in daily activities: A focus on educational level
No full textBackground This study investigated the association between public perception of the appropriateness of management strategies implemented during the COVID-19 pandemic and the level of disturbances in daily activities reported by the general population. Methods This cross-sectional study used Korea Community Health Survey conducted from August to November 2020. Public perception of COVID-19 management strategies included those implemented by the government (central, city or provincial, and administrative districts), the mass media, regional medical institutions, and neighbors. The subjective level of disturbances in daily activities was measured using a 0–100 numeric rating scale developed by Korea Disease Control and Prevention Agency. Multivariable linear regression analysis was used. A subgroup analysis was conducted based on education level. Results The present study analyzed 211,353 participants. Compared to individuals who perceived that the management strategies implemented during the pandemic was ‘highly appropriate,’ those who reported ‘mediocre appropriateness’ (β: -1.96, p-value: <0.001) or ‘low appropriateness’ (β: -3.60, p-value: 0.010) reported higher levels of subjective disturbances. The appropriateness of measures implemented by the mass media was associated with levels of subjective disturbances felt by individuals of lower education with statistical significance, whereas that applied by the mass media and the government were important in those with higher education. Conclusions The findings suggest the importance of public perception of management strategies when implementing containment policies and minimizing its disturbances on daily lives is essential. © 2023 Ju et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Morphology and oxygen barrier properties of LDPE/EVOH blends
No full textThe morphology of the dispersed phase in immiscible polymer blends can have a significant effect on the final may be omitted physical properties. Laminar dispersion of an ethylene vinyl alcohol copolymer (EVOH) with high oxygen barrier properties was obtained in the matrix of low density polyethylene (LDPE) when extruded through an annular blown film die. A large range of morphology was observed and indicated that the main factors determining the morphology of the blends were the composition, the viscosity ratio of the components, the processing conditions, and the elongational fields at the exit of the die. Increasing amount of EVOH (from 5 to 20 vol%) resulted in increasing number of stacked layers. Highly elongated laminar structure was formed when the viscosity ratio (sic) was close to one and slightly lower. Large predeformed domains in the extruder outlet (before drawing and blowing) with short residence time under high screw rpm and low viscosity ratio in the die temperature favored the formation of well-developed laminar structure. Oxygen permeation tests have shown high barrier effects due to the formation of the laminar dispersion which acted as barriers to the permeant molecules by providing a long tortuous path
KRAMERS RESTRICTED HARTREE-FOCK METHOD FOR POLYATOMIC-MOLECULES USING ABINITIO RELATIVISTIC EFFECTIVE CORE POTENTIALS WITH SPIN ORBIT OPERATORS
No full textA two-component Kramers' restricted Hartree-Fock method (KRHF) has been developed for the polyatomic molecules with closed shell configurations. The present KRHF program utilizes the relativistic effective core potentials with spin-orbit operators at the Hartree-Fock (HF) level and produces molecular spinors obeying the double group symmetry. The KRHF program enables the variational calculation of spin-orbit interactions at the HF level. KRHF calculations have been performed for the HX, X2, XY(X, Y = I, Br), and CH3I molecules. It is demonstrated that the orbital energies from KRHF calculations are useful for the interpretation of spin-orbit splittings in photoelectron spectra. In all molecules studied, bond lengths are only slightly expanded, harmonic vibrational frequencies are reduced, and bond energies are significantly decreased by the spin-orbit interactions
ANALYSIS OF TIG WELDING ARC USING BOUNDARY-FITTED COORDINATES
No full textThe characteristics of argon arc in tungsten inert gas (TIG) welding have been studied by considering the electrode shape which has an effect on the current density distribution near the electrode tip. For including the electrode surface configuration into the solution domain, the boundary-fitted coordinate system was employed. Then, a non-rectangular computational region in the physical domain was transformed into a rectangular area with uniformly spaced grids in the computational domain using the second-order central difference method. With the geometric transformation coefficients, the finite difference equations were derived in the computational transformed domain. As the most critical boundary condition, the normal current density distribution entering an electrode surface was postulated by the Gaussian distribution in consideration of the geometry of the electrode shape. For examining the simulated results, the temperature profile was compared with the experimental measurement of the previous research. The transferring phenomena on the base plate, such as current density, heat flux, arc pressure and drag force, were also calculated, because they are necessary data for analysing the molten pool during welding.
ABINITIO ELECTRONIC-STRUCTURE CALCULATIONS OF O2 USING COUPLED CLUSTER APPROACHES AND MANY-BODY PERTURBATION-THEORY
No full textThe ground state of the oxygen molecule is calculated by various methods of coupled cluster approaches and many body perturbation theory using a double zeta plus polarization basis set and the UHF reference state. All the methods employed are capable of describing the oxygen molecule near the equilibrium bond length and the separated atom but do not correctly depict the breaking of the multiple bond. For this basis set, including more correlations does not necessarily improve the agreement with experiment for molecular properties such as bond lengths and dissociation energies
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