Vibration behavior of functionally graded sandwich beam with porous core and nanocomposite layers

Hua Si,Daoming Shen,Jinhong Xia,Vahid Tahouneh 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.36 No.1

This paper presents the influence of carbon nanotubes (CNTs) waviness, aspect ratio, internal pores and graphene platelets (GPLs) on the vibrational behavior of functionally graded nanocomposite sandwich beams resting on two-parameter elastic foundations. The distributions of CNTs are considered functionally graded (FG) or uniform along the thickness of upper and bottom layers of the sandwich beam and their mechanical properties are estimated by an extended rule of mixture. In this study, the classical theory concerning the mechanical efficiency of a matrix embedding finite length fibers has been modified by introducing the tube-to-tube random contact, which explicitly accounts for the progressive reduction of the tubes’ effective aspect ratio as the filler content increases. The core of structure is porous and the internal pores and graphene platelets (GPLs) are distributed in the matrix of core either uniformly or non-uniformly according to three different patterns. The elastic properties of the nanocomposite are obtained by employing Halpin-Tsai micromechanics model. The equations of motion are derived based on Timoshenko beam theory and employing Hamilton’s principle. The problem is modeled using a semi-analytical approach composed of generalized differential quadrature method (GDQM) and series solution adopted to solve the equations of motion. Detailed parametric studies are carried out to investigate carbon nanotubes (CNTs) waviness, CNT aspect ratio, porosity coefficient, porosity distribution, graphene platelets (GPLs) distribution, Winkler foundation modulus, shear elastic foundation modulus and geometrical conditions on the vibrational behavior of the sandwich structure.

Foxl2 of the Hong Kong catfish (Clarias fuscus): cDNA cloning, tissue distribution and changes in gene expression towards methyltestosterone, estradiol and letrozole exposure of the fries during gonadal differentiation

Si-ping Deng,Chun-hua Zhu,Jing Sun,Wen-da Wang,Tian-li Wu,Hua-pu Chen,Shang-li Shi,Guang-li Li 한국유전학회 2015 Genes & Genomics Vol.37 No.8

Winged helix/forkhead transcription factor gene 2 (Foxl2) plays a crucial role during early ovarian development in fish. Sex steroids and aromatase inhibitors can regulate gonadal differentiation in teleosts. To address the role of Foxl2 in gonadal differentiation, foxl2 was isolated and characterized from the Hong Kong catfish, Clarias fuscus. Tissue distribution analysis by quantitative real-time PCR (qPCR) showed that the foxl2 mRNA was highest in the ovaries; moderate in the female pituitary and hypothalamus; but weak in the forebrain, liver, testis and male pituitary, with a sexually dimorphic pattern in which there was higher expression overall in females versus males. Treatment of the fries during the period of gonadal differentiation [2–30 days post hatching (dph)] with 17amethyltestosterone (MT), an aromatase inhibitor (letrozole) and 17b-estradiol (E2) affected the expression of foxl2. The expression of foxl2 was highest before gonadal differentiation (12 dph), but decreased significantly after gonadal differentiation (18-30 dph). In addition, MT and letrozole were able to down-regulate foxl2, but E2 up-regulated foxl2 during gonadal morphological differentiation. These results indicate the significant roles of Foxl2 in the gonadal differentiation of C. fuscus.

A Study on High Frequency-Plasma Enhanced Chemical Vapor Deposition Silicon Nitride Films for Crystalline Silicon Solar Cells

Zhen-Hua Li,Si-Cheol Roh,Dong-Yeol Ryu,Jeong-Ho Choi,Hwa-Il Seo,김영철 한국전기전자재료학회 2011 Transactions on Electrical and Electronic Material Vol.12 No.4

SiNx:H films have been widely used for anti-reflection coatings and passivation for crystalline silicon solar cells. In this study, SiNx:H films were deposited using high frequency (13.56 MHz) direct plasma enhanced chemical vapor deposition, and the optical and passivation properties were investigated. The radio frequency power, the spacing between the showerhead and wafer, the NH3/SiH4 ratio, the total gas flow, and the N2 gas flow were changed over certain ranges for the film deposition. The thickness uniformity, the refractive index, and the minority carrier lifetime were then measured in order to study the properties of the film. The optimal deposition conditions for application to crystalline Si solar cells are determined from the results of this study.

A Study on High Frequency-Plasma Enhanced Chemical Vapor Deposition Silicon Nitride Films for Crystalline Silicon Solar Cells

Li, Zhen-Hua,Roh, Si-Cheol,Ryu, Dong-Yeol,Choi, Jeong-Ho,Seo, Hwa-Il,Kim, Yeong-Cheol The Korean Institute of Electrical and Electronic 2011 Transactions on Electrical and Electronic Material Vol.12 No.4

SiNx:H films have been widely used for anti-reflection coatings and passivation for crystalline silicon solar cells. In this study, SiNx:H films were deposited using high frequency (13.56 MHz) direct plasma enhanced chemical vapor deposition, and the optical and passivation properties were investigated. The radio frequency power, the spacing between the showerhead and wafer, the $NH_3/SiH_4$ ratio, the total gas flow, and the $N_2$ gas flow were changed over certain ranges for the film deposition. The thickness uniformity, the refractive index, and the minority carrier lifetime were then measured in order to study the properties of the film. The optimal deposition conditions for application to crystalline Si solar cells are determined from the results of this study.

Characteristics of Low - Fat Cheddar Cheese Made with Added Micrococcus sp .

Si Kyung Lee,Un Hua Pek,Hyun Kyu Joo,Elmer H . Marth 한국응용생명화학회 1992 한국응용생명화학회 학술발표회 Vol.1992 No.-

The main purpose of this study was to determine the effects of Micrococcus sp. LL3 on accelerating proteolysis, flavor development and characteristics of low-fat Cheddar cheese as a potential agent for industrial application, and to optimize cultural conditions for cell mass production. Optimum temperature for cell growth and caseinolysis was 30 ℃ and 35 ℃ respectively, and optimum pH was 7.0. Monosaccharides like glucose, mannose and fructose were more excellent as carbon source, but arabinose and xylose markedly inhibited cell growth and caseinolysis. Among the organic nutrients, yeast extract was more effective for cell growth and for caseinolysis. However, inoranic nitrogen sources were less effective than organic sources. Urea inhibited cell growth severely. Cell growth and caseinolysis were rather increased a little in broth containing 1% NaCl, and Micrococcus sp. LL3 was very tolerant until NaCl concentration in broth added to 9%. Addition of vitamin did not affect cell growth and caseinolysis in level of 0.1 ㎍/㎖ concentration. Cell growth and caseinolysis were activiated by addition of glutamic acid and MgSO₄ with concentration of 0.2% and 0.5% respectively. Production of aminopeptidase which cleaved polypeptides was the highest in early stationary phase during cell growth. There was no difference in acidity changes in the course of cheese manufacture and in chemical component in 6-month old cheese through addition of Micrococcus sp. LL3 to cheese. It was however possible to note a significant increase in the value for TCA solube N and PTA soluble N in cheese with added adjunct compared to the control cheese. Values for TCA soluble N were 14, 21 and 28% higher khan that of the control cheese for 6-month old cheeses with added CFE, FD and live cells of Micrococcus sp. LL3. Using electrophoresis in polysacrylamide gels, casein hydrolysis appeared also to be more extensive in experimental cheeses ripened at 10 ℃ for 5 and 6 months than in the control cheese. The population of starter and lactic acid bacteria was not affected by addition of Micrococcus sp. LL3 as ajunct. Starter bacteria decreased slowly but lactic acid bacteria increased rapidly with time. Microflora of 3-month old low-fat Cheddar cheese represented a sequene of changes in which Lactobacillus sp. replaced the initial flora of Streptococcus sp. When Micrococcus sp. LL3 was added in cheese, no marked flavor defects developed and bitterness decreased more than in control cheese. Panelists gave higher flavor score and overall preference score to experimental cheeses than to the control cheese.

Resource Allocation for Heterogeneous Service in Green Mobile Edge Networks Using Deep Reinforcement Learning

( Si-yuan Sun ),( Ying Zheng ),( Jun-hua Zhou ),( Jiu-xing Weng ),( Yi-fei Wei ),( Xiao-jun Wang ) 한국인터넷정보학회 2021 KSII Transactions on Internet and Information Syst Vol.15 No.7

The requirements for powerful computing capability, high capacity, low latency and low energy consumption of emerging services, pose severe challenges to the fifth-generation (5G) network. As a promising paradigm, mobile edge networks can provide services in proximity to users by deploying computing components and cache at the edge, which can effectively decrease service delay. However, the coexistence of heterogeneous services and the sharing of limited resources lead to the competition between various services for multiple resources. This paper considers two typical heterogeneous services: computing services and content delivery services, in order to properly configure resources, it is crucial to develop an effective offloading and caching strategies. Considering the high energy consumption of 5G base stations, this paper considers the hybrid energy supply model of traditional power grid and green energy. Therefore, it is necessary to design a reasonable association mechanism which can allocate more service load to base stations rich in green energy to improve the utilization of green energy. This paper formed the joint optimization problem of computing offloading, caching and resource allocation for heterogeneous services with the objective of minimizing the on-grid power consumption under the constraints of limited resources and QoS guarantee. Since the joint optimization problem is a mixed integer nonlinear programming problem that is impossible to solve, this paper uses deep reinforcement learning method to learn the optimal strategy through a lot of training. Extensive simulation experiments show that compared with other schemes, the proposed scheme can allocate resources to heterogeneous service according to the green energy distribution which can effectively reduce the traditional energy consumption.

Polymorphisms in TYMS for Prediction of Capecitabine-Induced Hand-Foot Syndrome in Chinese Patients with Colorectal Cancer

Si-Qi Dong,Tong-Min Wang,Jiang-Bo Zhang,Yong-Qiao He,Wen-Qiong Xue,Zi-Yi Wu,Da-Wei Yang,Lian-Jing Cao,Jing-Wen Huang,Xi-Zhao Li,Pei-Fen Zhang,Xiao-Hui Zheng,Wei-Hua Jia 대한암학회 2021 Cancer Research and Treatment Vol.53 No.3

Purpose Capecitabine is an extensively used oral prodrug of 5-fluorouracil in treatment of colon cancer and is known to cause hand-foot syndrome (HFS). As the target enzyme for capecitabine, thymidylate synthase (TYMS) plays a key role for 5-fluorouracil metabolism and has been associated with some side effects caused by capecitabine. The aim of our study is to identify the possible genetic predictors of capecitabine-induced HFS (CAP-HFS) in Chinese colorectal cancer patients.Materials and Methods Whole exons of TYMS were sequenced for 288 extreme phenotype HFS patients, including 144 severe or early-onset (first 2 cycles) moderate HFS extreme cases and 144 extreme controls with no reported HFS. The associations between polymorphisms and CAP-HFS were analyzed using logistic regression under an additive model.Results We identified a novel risk mutation (c.1A>G, chr18:657743), was associated with severe HFS in an extreme case who was affected during the first cycle of treatment. Moreover, we identified three new variants, rs3786362, rs699517, rs2790, and two previously reported variants, 5’VNTR 2R/3R and 3′-untranslated region 6-bp ins-del, which were significantly associated with CAP-HFS (p < 0.05). In silico analysis revealed that the effect of these polymorphisms in the TYMS region on the development of HFS might not be restricted solely to the regulation of TYMS expression, but also the TYMS catalytic activity through the indirect effect on ENOSF1 expression.Conclusion This study identified new polymorphisms in TYMS gene significantly associated with CAP-HFS, which may serve as useful genetic predictors for CAP-HFS and help to elucidate the underlying mechanism of HFS.

Effects of graphite additives in electrolytes on the microstructure and corrosion resistance of Alumina PEO coatings

Guo-Hua Lv,Huan Chen,Wei-Chao Gu,Wen-Ran Feng,Li Li,Er-Wu Niu,Xian-Hui Zhang,Si-Ze Yang 한국물리학회 2009 Current Applied Physics Vol.9 No.3

In the present work, graphite grains of different sizes were added into the electrolyte to prepare ceramic coatings on aluminum by plasma electrolytic oxidation (PEO). Scanning electron microscopy (SEM) coupled with an energy dispersive X-ray analysis system (EDX), Raman spectroscopy and X-ray diffractometer (XRD) were used to characterize the coatings. A three-electrode system was used to evaluate the corrosion performances of the coatings in a 3.5 wt.% NaCl solution. It was found that the morphology and corrosion performance of the coatings were significantly influenced by the size of the graphite grains. Compared with bigger graphite grains, finer ones were involved in the oxidation process and embedded within the ceramic coatings, which made the coatings less porous and more compact. Thus, the corrosion resistance of the coatings with embedded graphite grains was greatly improved. In the present work, graphite grains of different sizes were added into the electrolyte to prepare ceramic coatings on aluminum by plasma electrolytic oxidation (PEO). Scanning electron microscopy (SEM) coupled with an energy dispersive X-ray analysis system (EDX), Raman spectroscopy and X-ray diffractometer (XRD) were used to characterize the coatings. A three-electrode system was used to evaluate the corrosion performances of the coatings in a 3.5 wt.% NaCl solution. It was found that the morphology and corrosion performance of the coatings were significantly influenced by the size of the graphite grains. Compared with bigger graphite grains, finer ones were involved in the oxidation process and embedded within the ceramic coatings, which made the coatings less porous and more compact. Thus, the corrosion resistance of the coatings with embedded graphite grains was greatly improved.

Investigation of plasma electrolytic oxidation process on AZ91D magnesium alloy

Guo-Hua Lv,Huan Chen,Li Li,Er-Wu Niu,Huan Pang,Bin Zou,Si-Ze Yang 한국물리학회 2009 Current Applied Physics Vol.9 No.1

Ceramic coatings oxidized for different time periods were prepared to characterize the plasma electrolytic oxidation (PEO) process of AZ91D magnesium alloy. The coatings were analyzed using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscope and potentiodynamic polarization measurement. The results show that the PEO coatings perform different growth behaviors at different PEO stages, and different morphologies are exhibited on α- and β-phase of Mg substrate. The corrosion resistance measurement predicates that within the first 30 min oxidation, coating oxidized for 20 min is the best corrosion resistant. Ceramic coatings oxidized for different time periods were prepared to characterize the plasma electrolytic oxidation (PEO) process of AZ91D magnesium alloy. The coatings were analyzed using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscope and potentiodynamic polarization measurement. The results show that the PEO coatings perform different growth behaviors at different PEO stages, and different morphologies are exhibited on α- and β-phase of Mg substrate. The corrosion resistance measurement predicates that within the first 30 min oxidation, coating oxidized for 20 min is the best corrosion resistant.

Characteristics of low - fat Chedder cheese made with added Micrococcus sp .

Lee, Si Kyung,P다, Un Hua,Joo, Hyun Kyu,Marth, Elmer H 한국농화학회 1992 Applied Biological Chemistry (Appl Biol Chem) Vol.35 No.5

The main purpose of this study was to determine the effects of Micrococcus sp. LL3 on accelerating proteolysis, flavor development and characteristics of low-fat Cheddar cheese as a potential agent for industrial application, and to optimize cultural conditions for cell mass production. Optimum temperature for cell growth and caseinolysis was 30 ℃ and 35 ℃ respectively, and optimum pH was 7.0. Monosaccharides like glucose, mannose and fructose were more excellent as carbon source, but arabinose and xylose markedly inhibited cell growth and caseinolysis. Among the organic nutrients, yeast extract was more effective for cell growth and for caseinolysis. However, inoranic nitrogen sources were less effective than organic sources. Urea inhibited cell growth severely. Cell growth and caseinolysis were rather increased a little in broth containing 1% NaCl, and Micrococcus sp. LL3 was very tolerant until NaCl concentration in broth added to 9%. Addition of vitamin did not affect cell growth and caseinolysis in level of 0.1 ㎍/㎖ concentration. Cell growth and caseinolysis were activiated by addition of glutamic acid and MgSO₄ with concentration of 0.2% and 0.5% respectively. Production of aminopeptidase which cleaved polypeptides was the highest in early stationary phase during cell growth. There was no difference in acidity changes in the course of cheese manufacture and in chemical component in 6-month old cheese through addition of Micrococcus sp. LL3 to cheese. It was however possible to note a significant increase in the value for TCA solube N and PTA soluble N in cheese with added adjunct compared to the control cheese. Values for TCA soluble N were 14, 21 and 28% higher khan that of the control cheese for 6-month old cheeses with added CFE, FD and live cells of Micrococcus sp. LL3. Using electrophoresis in polysacrylamide gels, casein hydrolysis appeared also to be more extensive in experimental cheeses ripened at 10 ℃ for 5 and 6 months than in the control cheese. The population of starter and lactic acid bacteria was not affected by addition of Micrococcus sp. LL3 as ajunct. Starter bacteria decreased slowly but lactic acid bacteria increased rapidly with time. Microflora of 3-month old low-fat Cheddar cheese represented a sequene of changes in which Lactobacillus sp. replaced the initial flora of Streptococcus sp. When Micrococcus sp. LL3 was added in cheese, no marked flavor defects developed and bitterness decreased more than in control cheese. Panelists gave higher flavor score and overall preference score to experimental cheeses than to the control cheese.