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Lei Gao,Feng Li,Ye Wang,Xing Mao Xiao,Peng Da Huo 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.8
Solid-state bonding of heterogeneous materials is one of the effective ways to achieve light weight. An extrusion formingprocess for Mg/Al thickness-oriented bonding sheet was carried out. Due to triaxial compressive stress in the extrusion container,the AZ31 and AA6061 billets were deformed and the bonding and forming of Mg/Al thickness-oriented sheet can berealized by this method. The observation results of the bonding position by using XRD, SEM and EDS showed that: at theforming temperature with 360–420 °C, it had a good bonding interface, and the width of the transition layer increased withthe increase of the forming temperature. The presence of brittle intermetallic compounds in the transition layer indicated thatmetallurgical bonding had occurred at the interface. Considering all factors comprehensively, when the forming temperaturewas 390 °C, the bonding quality was appropriate. Its tensile-shear strength was 42 MPa, the width of the interface transitionlayer was about 10 μm, and the microhardness was about 164.3 HV. This method provided scientific guidance and technicalreserves for green forming of Mg/Al sheets.
Chemical Budgets in Intensive Carp Ponds
Peng, Lei,Oh, Sung-Yong,Jo, Jae-Yoon 한국수산학회 2003 Fisheries and Aquatic Sciences Vol.6 No.4
Budgets for water, nitrogen, and chemical oxygen demand (COD) were determined in two 0.012 ha earthy-bottom ponds stocked with Israeli strain common carp at an initial stocking density of 20 fish/m3. Total ammonia nitrogen (TAN) concentrations increased continuously but later decreased in pond A as a consequence of high nitrification. COD concentrations increased during the experimental period due to the accumulation of feed input. Nutrient budgets showed that feed represented 94-95% of nitrogen input and about 99% of organic matter input. Fish harvest accounted for 40% of nitrogen and organic matter input. Seepage and water exchange removed 15-17% of nitrogen input but only 1-2% of organic matter. Draining of the ponds removed 20-26% of input nitrogen, mostly in inorganic forms, but removed only minus organic matter. Fish and water column respiration accounted for 39% of organic matter input, and benthic respiration accounted for 7-1 2% of organic matter input. No significant change of nitrogen and organic matter in both pond bottoms were found during the three-month growth period. The unrecovered input nitrogen, about 6.3- 13%, was lost through denitrification and ammonia volatilization. On a dry matter basis, fish growth removed 31% of total feed input and left 69% as metabolic wastes.
Removal of Total Suspended Solids by a Foam Fractionator in a Simulated Seawater Aquaculture System
Peng, Lei,Jo, Jae-Yoon The Korean Society of Fisheries and Aquatic Scienc 2003 韓國養殖學會誌 Vol.16 No.4
In a simulated seawater aquaculture system, effects of different operating factors like the superficial air velocity (SAY), hydraulic residence time (HRT), protein concentration and foam overflow height on the removal of total suspended solids (TSS) by a foam fractionator, with 20 cm diameter and 120 cm height, were investigated. This experiment was performed on batch and consecutive modes for different combinations of the tested factors, using synthetic wastewater. In 5 consecutive trials, TSS concentration in culture tank water decreased faster, when the foam fractionator was operated at higher SAV and lower HRT. In batch trials, with increasing SAV, TSS removal rate increased, but decreased with increasing HRT. Higher protein concentration in the bulk solution resulted in higher TSS removal rate. TSS concentration in the collected foam condensates increased but the foam overflow rate decreased with increasing foam overflow height. Foam fractionation was effective for removing TSS in seawater aquaculture systems and its performance largely depended on the operating parameters, especially superficial air velocity.
Lei Peng,Hong Ryul Ahn,Sang Hoon Jung,Yongsoo Choi 대한화학회 2020 Bulletin of the Korean Chemical Society Vol.41 No.2
Although recent pharmacological studies have demonstrated the beneficial effects of the ethanol extract of Diospyros kaki (EEDK) against eye diseases in vitro and in vivo, they could not conclude whether two strong antioxidants, quercetin and kaempferol, in the EEDK were bioavailable in eye tissue after oral administration. A method based on ultra-performance liquid chromatography coupled with triple quadrupole tandem mass spectrometry (UPLC-MS/MS) was herein developed for the highly selective and sensitive quantification of quercetin and kaempferol in rat eye tissue. The method was applied to investigate the distribution of quercetin and kaempferol in rat eyes after oral administration of EEDK at 0, 5, and 35?min after it was successfully validated for specificity, linearity, a low limit of quantification, precision, accuracy, extraction recovery, and matrix effect. The distribution of quercetin and kaempferol in rat eyes at 35?min after oral administration of the EEDK was 0.0099% and 0.0041%, respectively. These results will be useful for the precise determination of optimized in vivo EEDK dose and time for the effective prevention and treatment of eye diseases.
Chemoenzymatic Synthesis of Dual-responsive Amphiphilic Block Copolymers and Drug Release Studies
Peng Chen,Ya-Peng Li,Shu-Wei Wang,Xin-Lei Meng,Ming Zhu,Jing-Yuan Wang 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.6
Dual-responsive amphiphilic block copolymers were synthesized by combining enzymatic ring-opening polymerization (eROP) of ε-caprolactone (CL) and ATRP of N,N-dimethylamino-2-ethyl methacrylate (DMAEMA). The obtained block copolymers were characterized by gel permeation chromatography (GPC), 1H NMR and FTIR-IR. The critical micelle concentration (CMC) of copolymer was determined by fluorescence spectra, it can be found that with hydrophilic block (PDMAEMA) increasing, CMC value of the polymer sample increased accordingly, and the CMC value was 0.012 mg/mL, 0.025 mg/mL and 0.037 mg/ mL for PCL50-b-PDMAEMA68, PCL50-b-PDMAEMA89, PCL50-b-PDMAEMA112, PCL50-b-PDMAEMA89 was chosen as drug carrier to study in vitro release profile of anti-cancer drug (taxol). The temperature and pH dependence of the values of hydrodynamic diameter (Dh) of micelles, and self-assembly of the resulting block copolymers in water were evaluated by dynamic light scattering (DLS). The result showed that with the temperature increasing and pH decreasing, the Dh decreased. Drug-loaded nanoparticles were fabricated using paclitaxel as model. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) had been explored to study the morphology of the hollow micelles and the nanoparticles, revealing well-dispersed spheres with the average diameters both around 80 nm. In vitro release kinetics of paclitaxel from the nanoparticles was also investigated in different conditions (pH and temperature, etc.), revealing that the drug release was triggered by temperature changes upon the lower critical solution temperature (LCST) at pH 7.4, and at 37 °C by an increase of pH.
Protein Removal by a Foam Fractionator in Simulated Seawater Aquaculture System
Lei Peng,조재윤,Sung-Yong Oh 한국해양과학기술원 2003 Ocean and Polar Research Vol.25 No.3
Effects of different operating factors including superficial air velocity (SAV), hydraulic residence time (HRT), protein concentration, and foam overflow height on protein removal by a foam fractionator in simulated seawater aquaculture system were investigated. This experiment was conducted on batch and consecutive modes at different combinations of the affecting factors. The foam fractionator had a diameter of 20 cm and a height of 120 cm and the experiment was conducted with synthetic wastewater. In 5 consecutive trials, protein concentrations in culture tank water decreased faster when the foam fractionator was operated at higher SAVs and lower HRTs. In batch trials, protein removal rates increased with an increase in SAV but decreased with an increase in HRT. Higher protein concentrations in the bulk solution resulted in higher protein removal rates. Protein concentrations in the collected foam condensates increased but the foam overflow rates decreased with the increase of foam overflow heights. The results of this experiment indicate that foam fractionation would be an effective way for protein removal in seawater aquaculture systems and the performance of the foam fractionator depends largely on the operating parameters, especially SAV.