Effects of α-Si₃N₄ seeds and sintering additives on properties of porous silicon nitride ceramics fabricated by carbothermal reduction

Yuan Lu,Ji-Qiang Gao,Jian-feng Yang 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.6

In this paper, porous Si3N4 ceramics were fabricated by carbothermal reduction between silicon dioxide and carbon [1]. The influences of α-Si3N4 seeds and sintering additives on the microstructure and mechanical properties of porous Si3N4 ceremics were investigated. XRD analysis proved the complete formation of a single-phase β-Si3N4. SEM analysis showed that the resultant porous Si3N4 ceramics had a fine microstructure and a uniform pore structure. The sintered sample with Lu2O3 as sintering additive showed finer, higher aspect ratio β-Si3N4 grains. The addition of Eu2O3 accelerated the densification of porous Si3N4 ceramics, decreased the porosity and increased the flexural strength. The addition of α-Si3N4 seeds accelerated the formation of the α-Si3N4 phase at a low temperature and the α-β phase transformation process at a high temperature. With an increase in the α-Si3N4 seeds content, the porosity decreased, and the flexural strength increased accordingly. In this paper, porous Si3N4 ceramics were fabricated by carbothermal reduction between silicon dioxide and carbon [1]. The influences of α-Si3N4 seeds and sintering additives on the microstructure and mechanical properties of porous Si3N4 ceremics were investigated. XRD analysis proved the complete formation of a single-phase β-Si3N4. SEM analysis showed that the resultant porous Si3N4 ceramics had a fine microstructure and a uniform pore structure. The sintered sample with Lu2O3 as sintering additive showed finer, higher aspect ratio β-Si3N4 grains. The addition of Eu2O3 accelerated the densification of porous Si3N4 ceramics, decreased the porosity and increased the flexural strength. The addition of α-Si3N4 seeds accelerated the formation of the α-Si3N4 phase at a low temperature and the α-β phase transformation process at a high temperature. With an increase in the α-Si3N4 seeds content, the porosity decreased, and the flexural strength increased accordingly.

Effect of Freeze Drying on the Liquid Penetration of Chinese fir wood

( Jian Xiong Lu ),( Zhi Yuan Lin ),( Jia Ji Jiang ),( Jing Hui Jiang ) 韓國木材工學會 2005 한국목재공학회 학술발표논문집 Vol.2005 No.-

Tetrazolium Violet Induced Apoptosis and Cell Cycle Arrest in Human Lung Cancer A549 Cells

( Jian Mei Lu ),( Xiao Hong Zhang ),( Nan Zhang ),( Qing Zhong Kong ),( Yun Feng Zhao ) 한국응용약물학회 2012 Biomolecules & Therapeutics(구 응용약물학회지) Vol.20 No.2

Tetrazolium violet is a tetrazolium salt and has been proposed as an antitumor agent. In this study, we reported for the fl rst time that tetrazolium violet not only inhibited human lung cancer A549 cell proliferation but also induced apoptosis and blocked cell cycle progression in the G1 phase. The results showed that tetrazolium violet signifl cantly decreased the viability of A549 cells at 5-15 M. Tetrazolium violet -induced apoptosis in A549 cells was confl rmed by H33258 staining assay. In A549, tetrazolium violet blocked the progression of the cell cycle at G1 phase by inducing p53 expression and further up-regulating p21/WAF1 expression. In addition, an enhancement in Fas/APO-1 and its two forms of ligands, membrane-bound Fas ligand (mFasL) and soluble Fas ligand (sFasL), as well as caspase, were responsible for the apoptotic effect induced by tetrazolium violet. The conclusion of this study is that tetrazolium violet induced p53 expression which caused cell cycle arrest and apoptosis. These fl ndings suggest that tetrazolium violet has strong potential for development as an agent for treatment lung cancer.

Object Recognition System of Sonar Image Based on Multiple Invariant Moments and BP Neural Network

Jianning Han,Peng Yang,Lu Zhang 보안공학연구지원센터 2014 International Journal of Signal Processing, Image Vol.7 No.5

Object Recognition System of Sonar Image plays an important role in the field of underwater defense According to pattern recognition theory, principle processes of a typical object recognition system is introduced . To achieve robust performance, image de-noising, sharpening, binary transformation, edge detection and other image processing techniques are discussed . The paper presents a novel object recognition system using multiple invariant moments as the main feature of the object, and the detected feature is trained by BP neural network so that the classification error can be minizied. Finally, we implemented the proposed approach by visual air plane recognition, the experimental results demonstrates the robustness and efficiency of the presented approach.

Hydrothermal Synthesis, Crystal Structure and EPR Property of Tetranuclear Copper(II) Cluster [Cu₄OCl₆(C₁₄H₁₂N₂)₄]

Jian, Fang-Fang,Zhao, Pu-Su,Wang, Huan-Xiang,Lu, Lu-De Korean Chemical Society 2004 Bulletin of the Korean Chemical Society Vol.25 No.5

The tetranuclear copper(II) cluster compound $[Cu_4OCl_6(C_{14}H_{12}N_2)_4]$ has been synthesized by hydrothermal reaction and studied by X-ray diffraction. The four copper(II) atoms locate four capsheaves of a tetrahedral skeletal structure and a oxygen atom as interstitial atom occupies the center position of the same tetrahedron, and each edge of the Cu-Cu tetrahedron is bridged by one ${\mu}_2$-Cl anion. The copper atom possesses slightly distorted trigonal bipyramidal geometry with three ${\mu}_2$-Cl atoms in equatorial position and the interstitial O atom and one N atom from 3-benzyl-benzimidazole ligand occupying axial position. The Cu-Cu distances are in the range of 3.0986-3.1162 ${\AA}$. The EPR spectrum suggested that the copper(II) ground state $d_{x2-y2}$ and the coordination geometry was trigonal bipyramidal.

Isolation of L-theanine from Tea Solution by Cation Exchange Resin in Batch and Fixed Bed Column

Jian-Hui Ye,Yi-Wen Luo,Hui-Ling Liang,Jian-Liang Lu,Jing Jin,Yue-Rong Liang,Xin-Qiang Zheng,Xian-Yang Luo 한국생물공학회 2011 Biotechnology and Bioprocess Engineering Vol.16 No.2

L-Theanine, a bioactive compound in tea, was isolated from tea solution using cation exchange resin no.732. The adsorption of L-theanine by cation exchange resin no.732 fit the Langmuir isotherm model and was a monolayer molecular interaction process. Thermodynamic studies revealed that the adsorption of L-theanine by resin no.732 was an exothermic and spontaneous physically driven process. The adsorption capacity was influenced by temperature, initial concentration, and pH. The L-theanine adsorption capacity under conditions at room temperature,pH 4.73, and initial L-theanine concentration 18 g/L was 241.731 ± 3.679 mg/g. The Thomas model was fit to describe the column adsorption data at different flow rates and initial concentrations. The L-theanine adsorbed by resin no.732 could be desorbed by 0.134 mol/L Na2HPO4aqueous solution with a recovery rate of 84.96%. These findings indicate that resin no.732 was a promising material for isolating L-theanine from tea solution.

Effect of Heat Treatment on the Lipophillic Pigments of Fresh Green Tea Liquor

Jian-Liang Lu,Zhan-Bo Dong,Shun-Shun Pan,Chen Lin,Xin-Qiang Zheng,Borthakur Devajit,Yue-Rong Liang 한국식품과학회 2009 Food Science and Biotechnology Vol.18 No.3

Changes in lipophillic pigments concentration and its relation to color of fresh green tea liquor during heat treatment were studied. The results showed liquor greenness decreased markedly with extension of incubation time at 55℃, while the brightness and yellowness changed a little. Significant increase in ‘a’ and ‘b’ values of tea liquor was observed at 95℃. Color change of liquor at 55℃ was accompanied by a decrease in the level of chlorophylls, lutein and neoxanthin, and an increase in the pheophytins and β-carotene levels. However, all pigments except β-carotene decreased with time extension at 95℃. Significant correlation was found between pigments and color difference index. The browning of fresh green tea liquor was attributed to vicissitudes of lipophillic pigments during heat treatment, especially to the change of chlorophylls/pheophytins ratio. Result also showed addition of Zn²? at 1.6 μ㏖/ℓ could partially alleviate the decrease in greenness during heat treatment.

Tunable multi-cycle THz generation in organic crystal HMQ-TMS.

Lu, Jian,Hwang, Harold Y,Li, Xian,Lee, Seung-Heon,Kwon, O-Pil,Nelson, Keith A Optical Society of America 2015 Optics express Vol.23 No.17

<P>We report on the generation of continuously tunable multi-cycle THz pulses with center frequencies from 0.3 to 0.8 THz in the organic nonlinear crystal, HMQ-TMS [2-(4-hydroxy-3-methoxystyryl)-1-methylquinolinium 2,-4,-6-trimethylbenzenesulfonate], by collinearly phase matched optical rectification of temporally shaped 800 nm pulses. The generation of harmonic frequency components inherent in the pulse shaper is selectively suppressed by varying the generation crystal thickness. THz pulses generated from HMQ-TMS show up to 20 times higher pulse energies compared to the benchmark inorganic THz generator ZnTe under identical conditions. The THz energy conversion efficiencies are measured to be on the order of 10^-5.</P>

Reflections on Recruitment Mode Innovation in the Context of the Digital Era

Jian Lu,Yeonggil Kim 동아시아무역학회 2023 Journal of East Asian Trade(JEAT) Vol.5 No.1

Purpose - Through the comparative analysis of digital recruitment mode and traditional recruitment mode, to explore how to use digital technology better to complement and improve the traditional recruitment mode, to improve the recruitment efficiency of enterprises, to match the required talents for enterprises more accurately, and to improve the competitiveness of enterprises in the market. Design/Methodology/Approach - This paper mainly collects and reads literature through online resources, books, and other means to obtain information on enterprise recruitment digital transformation and other relevant research information, and through the study of the literature, learn the practical methods of recruitment digital transformation, and provide ideas and references for the countermeasures of enterprise recruitment digital transformation Findings - In the context of the era of digitalization, the traditional recruitment model is no longer applicable. Digital recruitment is the inevitable trend of the times, and digital recruitment can help companies reduce recruitment costs, improve recruitment efficiency, and more efficient, accurate recruitment to the target talent. Research Implications - The gradual rise of digital recruitment so that enterprises gradually realize that digital recruitment in talent recruitment has great advantages, but also to the traditional recruitment mode of supplementation and reform, this paper in the recruitment management work-related concepts, principles of the premise, combined with the actual development of recruitment management work, the actual development of recruitment management at the moment. Through the relevant data, specifically analyzing the digital transformation of recruitment compared with traditional recruitment in terms of time, efficiency, information, and other dimensions of the difference, and the impact of the transformation on the enterprise, the digital transformation of the recruitment of enterprises has a certain practical reference significance.

Analysis of Volatile Compounds of Jasmine Scented Tea during the Orthodox Manufacturing Process Using HS-SPME/GC-MS

Jian Lu,De-Jun Fu,Dong-Fen Wu,Yu Liu,Yao-Ping Luo 한국차학회 2015 한국차학회지 Vol.- No.S

Volatile components of jasmine-scented tea during the orthodox manufacturing process were extracted using Headspace solid-phase microextraction (HS-SPME) and the major flavor compounds were identified by Gas chromatography-mass spectrometry/Retention indices (GC-MS/RI). The major volatile compounds extracted by SDE could also be obtained by HS-SPME, which appears more suitable for extraction of aromatic compounds, for its advantages of simplicity and convenience. The GC-MS chromatograms of tea samples showed that the aromatic constituents of jasmine tea had been identified in composition after 1st scenting, which contained 6 apparently high peaks representing linalool, benzyl acetate, α-farnesene, (Z)-3-hexenyl benzoate, methyl anthranilate, and indole. According to the change of peak area of major volatile compounds, (Z)-3-hexenyl acetate and (Z)-3-hexenyl butyrate with green grass aroma reduced by 71.13% and 63.10% respectively in jasmine tea product, while 7 compounds with favorable flowery fruity aroma-benzyl acetate, (Z)-3-hexenyl benzoate, linalool, benzyl alcohol, α-farnesene, methyl anthranilate and indole- increased by 17.84%, 28.33 times, 32.49%, 1.70 times, 6.67 times, 11.84 times and 21.48 times respectively, comparing to the base tea. Besides, nerolidol (fruity-flowery) and germacrene D (woody), not detected in the base tea also gradually increased. The quality grade of jasmine tea was potentially correlated to the ratio of peak area of the 9 favorable compounds to that of the 2 grass compounds. After 1st scenting, the peak areas of compounds from jasmine flower increased by 1.81×105-18.24×105, and decreased by 36.14%-69.95% after the 1st drying. The peak areas of some components detected in both the base tea and jasmine flowers, like (Z)-3-hexenyl acetate and methyl salicylate, increased by 9.05%-57.60% of those of the base tea after 1st scenting, and lost more than 100% after the 1st drying, while the increased peak areas of some other components both detected, like α-farnesene and indole, were more than peak areas of the base tea, with 30%- 95% loss after the 1st drying. The content change tendency of volatiles during 2nd scenting and the 2nd drying were consistent with those during 1st scenting and the 1st drying. After raising fragrance, the contents of some low boiling point volatiles and compounds not detected in the base tea increased.