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911.
Ji Hyun Lee Min Kyeong Seo Hyeon Joo Ham Sowoon Seo Dongwoo Shin Hyung Il Kim 《Journal of separation science》2023,46(11):2200963
The consumption of food and drugs adulterated with female sex hormones can have an extremely adverse effect on human health. Therefore, developing appropriate monitoring methods for the identification of various exogenous female sex hormones is crucial for minimizing and eliminating the related health risks. Herein, 17 female hormones categorized into two groups: estrogen and progestin, were analyzed using reversed-phase liquid chromatography coupled to Orbitrap or triple quadrupole mass spectrometry. The fragmentation patterns for all compounds were discovered, and fragmented structures were also derived from them through liquid chromatography–high-resolution mass spectrometry followed by qualitative sample analysis. In addition, a quantitative analysis of 67 samples of illicit drugs and dietary supplements was performed using the validated liquid chromatography-tandem mass spectrometry method. Female hormone components were detected in two samples of an unauthorized injectable solution and a tablet-type drug. Medroxyprogesterone was detected in the samples in the range of 96.4–206 ng/g. Notably, eight components similar in structure to steroids were simultaneously detected as male sex hormones by confirming their fragmentation ion patterns using liquid chromatography–high-resolution mass spectrometry. The developed methods thus offer a dependable and practically applicable approach for the screening and detection of exogenous female sex hormones in real food and drug samples to ensure public health. 相似文献
912.
We have controlled the molecular orientation of nematic and smectic A liquid crystal (LC) phases in a porous anodic aluminium oxide (AAO) film, in which the pore diameter was varied from 20 nm to 100 nm. Surface anchoring to induce planar and homeotropic molecular arrangement was controlled by chemical modification of the AAO inner surface. Direct observation of the molecular orientation of LC phases was performed using grazing incidence X-ray diffraction technique, showing in-plane and out-of-plane molecular orientation, and the corresponding layer orientation. The systematic investigation of LC phases under nanoconfinement will be useful to design various kinds of physicochemical environments to control the orientation of other soft matters. 相似文献
913.
Low Level Light Therapy Modulates Inflammatory Mediators Secreted by Human Annulus Fibrosus Cells during Intervertebral Disc Degeneration In Vitro 下载免费PDF全文
Kyoung Soo Kim Chang Min Yoo Ga Eun Jo Joo Han Kim Hyuk Choi 《Photochemistry and photobiology》2015,91(2):403-410
Intervertebral disc degeneration (IVD) is one of the important causes of low back pain and is associated with inflammation induced by interaction between macrophages and the human annulus fibrosus (AF) cells. Low‐level light therapy (LLLT) has been widely known to regulate inflammatory reaction. However, the effect of LLLT on macrophage‐mediated inflammation in the AF cells has not been studied till date. The aim of this study is to mimic the inflammatory microenvironment and to investigate the anti‐inflammatory effect of LLLT at a range of wavelengths (405, 532 and 650 nm) on the AF treated with macrophage‐like THP‐1 cells conditioned medium (MCM) containing proinflammatory cytokines and chemokines (interleukin‐1beta, tumor necrosis factor‐alpha, interleukin‐6 and 8). We observed that AF cells exposed to MCM secrete significantly higher concentrations of IL‐6, IL‐8, IL‐1β and TNF‐α. LLLT markedly inhibited secretion of IL‐6 at 405 nm in a time‐dependent manner. Level of IL‐8 was significantly decreased at all wavelengths in a time‐dependent manner. We showed that MCM can induce the inflammatory microenvironment in AF cells and LLLT selectively suppressed IL‐6 and 8 levels. The results indicate that LLLT is a potential method of IVD treatment and provide insights into further investigation of its anti‐inflammation effect on IVD. 相似文献
914.
915.
Linear stability of fully developed two-dimensional periodic steady flows in sinusoidal wavy-walled channels is investigated numerically. Two types of channels are considered: the geometry of wavy walls is identical and the location of the crest of the lower and upper walls coincides (symmetric channel) or the crest of the lower wall corresponds to the furrow of the upper wall (sinuous channel). It is found that the critical Reynolds number is substantially lower than that for plane channel flow and that when the non-dimensionalized wall variation amplitude is smaller than a critical value (about 0.26 for symmetric channel, 0.28 for sinuous channel), critical modes are three-dimensional stationary and for larger , two-dimensional oscillatory instabilities set in. Critical Reynolds numbers of sinuous channel flows are smaller for three-dimensional disturbances and larger for two-dimensional disturbances than those of symmetric channel flows. The disturbance velocity distribution obtained by the linear stability analysis suggests that the three-dimensional stationary instability is mainly caused by local concavity of basic flows near the reattachment point, while the critical two-dimensional mode resembles closely the Tollmien–Schlichting wave for plane Poiseuille flow. 相似文献
916.
Hyun Jung Kwak Dong Won Park Ji-Young Seo Ji-Yong Moon Tae Hyung Kim Jang Won Sohn Dong Ho Shin Ho Joo Yoon Sung Soo Park Sang-Heon Kim 《Experimental & molecular medicine》2015,47(12):e198
Airway remodeling is a key characteristic of chronic asthma, particularly in patients with a fixed airflow limitation. The mechanisms underlying airway remodeling are poorly understood, and no therapeutic option is available. The Wnt/β-catenin signaling pathway is involved in various physiological and pathological processes, including fibrosis and smooth muscle hypertrophy. In this study, we investigated the roles of Wnt/β-catenin signaling in airway remodeling in patients with asthma. Wnt7a mRNA expression was prominent in induced sputum from patients with asthma compared with that from healthy controls. Next, we induced a chronic asthma mouse model with airway remodeling features, including subepithelial fibrosis and airway smooth muscle hyperplasia. Higher expression of Wnt family proteins and β-catenin was detected in the lung tissue of mice with chronic asthma compared to control mice. Blocking β-catenin expression with a specific siRNA attenuated airway inflammation and airway remodeling. Decreased subepithelial fibrosis and collagen accumulation in the β-catenin siRNA-treated mice was accompanied by reduced expression of transforming growth factor-β. We further showed that suppressing β-catenin in the chronic asthma model inhibited smooth muscle hyperplasia by downregulating the tenascin C/platelet-derived growth factor receptor pathway. Taken together, these findings demonstrate that the Wnt/β-catenin signaling pathway is highly expressed and regulates the development of airway remodeling in chronic asthma. 相似文献
917.
A Morphological Transition of Inverse Mesophases of a Branched‐Linear Block Copolymer Guided by Using Cosolvents 下载免费PDF全文
Yunju La Tae Hyun An Prof. Tae Joo Shin Dr. Chiyoung Park Prof. Kyoung Taek Kim 《Angewandte Chemie (International ed. in English)》2015,54(36):10483-10487
We report here a strategy for influencing the phase and lattice of the inverse mesophases of a single branched‐linear block copolymer (BCP) in solution which does not require changing the structure of the BCP. The phase of the self‐assembled structures of the block copolymer can be controlled ranging from bilayer structures of positive curvature (polymersomes) to inverse mesophases (triply periodic minimal surfaces and inverse hexagonal structures) by adjusting the solvent used for self‐assembly. By using solvent mixtures to dissolve the block copolymer we were able to systematically change the affinity of the solvent toward the polystyrene block, which resulted in the formation of inverse mesophases with the desired lattice by self‐assembly of a single branched‐linear block copolymer. Our method was also applied to a new solution self‐assembly method for a branched‐linear block copolymer on a stationary substrate under humidity, which resulted in the formation of large mesoporous films. Our results constitute the first controlled transition of the inverse mesophases of block copolymers by adjusting the solvent composition. 相似文献
918.
We investigate the layer undulations that appear in smectic A liquid crystals when a magnetic field is applied in the direction
parallel to the smectic layers. In an earlier work (García-Cervera and Joo in J Comput Theor Nanosci 7:795–801, 2010) the authors characterized the critical field using the Landau–de Gennes model for smectic A liquid crystals. In this paper,
we obtain an asymptotic expression of the unstable modes using Γ-convergence theory, and a sharp estimate of the critical field. Under the assumption that the layers are fixed at the boundaries,
the maximum layer undulation occurs in the middle of the cell and the displacement amplitude decreases near the boundaries.
Our estimate of the critical field is consistent with the Helfrich–Hurault theory. When natural boundary conditions are considered,
the displacement amplitude does not diminish near the boundary, in sharp contrast with the Dirichlet case, and the critical
field is reduced compared to the one calculated in the classical theory. This is consistent with the experiments carried out
by Ishikawa and Lavrentovich (Phys Rev E 63:030501(R), 2001). Furthermore, we prove the existence and stability of the solution to the nonlinear system of the Landau–de Gennes model
using bifurcation theory. Numerical simulations are used to illustrate the predictions of the analysis. 相似文献
919.
Mode interaction is studied via direct numerical simulations of a Mach 4.5 boundary layer with discrete and continuous modes
imposed at the inflow. An approximate decoupling procedure is developed to create separate vortical, acoustic and entropic
continuous mode components. Oblique horizontal vorticity modes induce boundary layer disturbances that grow with downstream distance,
similarly to their incompressible counterpart. One salient difference is that a low frequency vorticity mode, alone, is found
to induce transition by spawning two-dimensional, unstable discrete modes. The discrete modes are non-linearly excited at
high harmonics of the inlet perturbation. Adding a Mack second mode, in addition to the vorticity mode, causes even earlier
transition, suggesting that, in supersonic flow, unstable discrete modes play a crucial role in breakdown of boundary-layer
streaks. 相似文献
920.
The structural, electrical, magnetic, and thermal properties were investigated for the nanocomposites of polypyrrole (PPy) and inorganic clay (Na+-montmorillonite) prepared by emulsion polymerization. Dodecylbenzenesulfonic acid (DBSA) was used as emulsifier (surfactant) and dopant. The X-ray diffraction (XRD) patterns and transmission electron microscopy (TEM) images showed that the conducting PPy was intercalated into the clay layers in nanoscale (<10 Å). The dc conductivity (σdc) of PPy–DBSA with clay was 6 S/cm, while that of PPy–DBSA without clay was 20 S/cm at room temperature (RT). Temperature dependence of σdc of both samples followed the three dimensional variable range hopping (VRH) model. From the g-value and the temperature dependence of EPR linewidth, paramagnetic signals were strongly affected by the partially negatively charged clay layers. The thermogravimetric analysis (TGA) and differential scanning calorimeter (DSC) showed that the clay induced the thermal stability of the systems. 相似文献