Soldering 6061 Al by Sn9Zn Coating With/Without Two Step Ultrasonic Effect

Hao Hong,Ding Min 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.8

The work described the effect of soldering 6061 Al by soldering coating with/without two step ultrasonic process, basedon Sn9Zn alloy prepared by high frequency melting and rapid solidification. The microstructure, interfacial morphology,shear strength and mechanical morphology of 6061 aluminum alloy soldered joints were compared and analyzed. Theresults showed that the ultrasonic soldering with coating by two step ultrasonic process technology could greatly improvethe morphology of the joints and refine the grain size. The solder layer with larger scallop shape was transformed into adense fine structure. After two step ultrasonic effect, the width of the joint was about 28% higher than that under the firstultrasonic process. The Zn-rich phase length decreased from an average of 90 μm to an average of 25 μm, about 27% of theoriginal length. The refinement of solder seam was related to the additional dissolved Al and IMC particles. The refinementmechanism was mainly sono-crystallization + sono-fragmentation with two step ultrasonic effect, which was different fromthe refinement mechanisms of the first ultrasonic effect with sono-crystallization. At the same time, the shear strength of6061 aluminum alloy joints bonded at low temperature could reach 230 MPa by two step ultrasonic effect. Compared withthe ultrasonic soldering with coating, the hardness and maximum strength were improved by 14.5% and 28%, respectively.

Low Temperature Soldering 6061 Aluminum Alloys by Using the Synthesized Sn9Zn Nano-Amorphous Particles

Hao Hong,Ding Min 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.8

To meet the growing demand of technologies of high performance electronics, nano-solders have been widely developed. In the present study, Sn-Zn nano-amorphous particles with core–shell structure were synthesized by a chemical reductionmethod with NaBH4 as reduction agent and Polyvinylpyrrolidone (PVP) as a stabilizer. The size distribution and thermalbehaviour of the as-synthesized nano-particles were controlled by the amount of PVP, whose concentration ranged from 3to 30 wt%. And the change was comparatively confirmed by TEM, DSC and XRD analysis. The results revealed that PVPconcentrations can not only regulate and control the size distribution of the nano-particles and the melting point, whichcould also change the ratio of amorphous shell to crystalline core in nanostructures. In addition, sintering behavior of thisnano-solder soldering 6061 aluminum alloys and its corresponding mechanical properties were evaluated based on SEM,XRD and the shear tests. The results turned out the best bonding quality was obtained under the condition of the content ofPVP is 10 wt%. The obtained shear strength was as high as 17.6 MPa, and the elemental composition of the thinner IMClayer was Al2Zn3,which revealed a good solderability property. The above analysis provided a new insight into the effects ofPVP content on the interfacial reaction mechanism. This bonding technology was suitable for the electronic devices bondedat low temperature.

Analysis and Optimization on U-shaped Damping Groove for Flow Ripple Reduction of Fixed Displacement Axial-Piston Pump

Hao-cen HONG,Bin ZHANG,Min YU,Qi ZHONG,Hua-yong YANG 한국유체기계학회 2020 International journal of fluid machinery and syste Vol.13 No.1

The periodic flow ripples and pressure pulsations in a fixed-displacement axial-piston pump will directly impact its dynamic characteristics. To reduce the discharge flow ripples and pressure pulsations is one of the design challenges. An optimizing method is investigated herein using numerical models. The U-shaped damping groove at the discharge kidney groove is the primary optimized object. The numerical models of a fixed-displacement axial-piston pump with nine pistons are proposed and developed by MATLAB/Simulink. The effects of width radius, groove depth and groove length angle on flow dynamics are discussed. The optimization models based on the root-mean-square, the pulsation and the suction-extrusion ratio are proposed. As results show that the optimized structure can decrease the flow ripples from 31.08% to 20.33%.

A Study on the Chinese of Korean E-learning Webpage Continuance Using Intention

Hong Hao Xu,Jong Ho Lee 한국유통과학회 2017 KODISA ICBE (International Conference on Business Vol.2017 No.-

In 1933, Korean culture entered into the Chinese market of which the Korean-style video products, costumes, Hip-Hop songs, Korean cuisine and other Korean styles attracted the attention of people. Korean hot air swept through China. Moreover, although there are many researches on e-learning in China, it is very few studies on e-learning in foreign languages such as Korean. Nowadays, the development prospects of online education in China are very good. The rising demand for education and the development of IT technology have provided the impetus for Chinese online education and education has become easy. According to the results, First of all, from the company’s point of view, the management of personal privacy is the most important to users. Secondly, the company should take seriously whether the user has experience or not in promoting a Korean learning website or discovering potential users. Thirdly, in order to gain the user’s satisfaction, it is necessary to improve the quality of corporate lecturers, strengthen web page design and system security, thereby improving user satisfaction and increasing the willingness to use continuously.

Enzymatic Biotransformation of Ginsenoside Rb1 and Gypenoside XVII into Ginsenosides Rd and F2 by Recombinant β-glucosidase from F lavobacterium johnsoniae

Hao Hong,Chang-Hao Cui,Jin-Kwang Kim,Feng-Xie Jin,Sun-Chang Kim,Wan-Taek Im 고려인삼학회 2012 Journal of Ginseng Research Vol.36 No.4

This study focused on the enzymatic biotransformation of the major ginsenoside Rb1 into Rd for the mass production of minor ginsenosides using a novel recombinant β-glucosidase from Flavobacterium johnsoniae. The gene (bglF3) consisting of 2,235 bp (744 amino acid residues) was cloned and the recombinant enzyme overexpressed in Escherichia coli BL21(DE3) was characterized. This enzyme could transform ginsenoside Rb1 and gypenoside XVII to the ginsenosides Rd and F2, respectively. The glutathione S-transferase (GST) fused BglF3 was purifi ed with GST-bind agarose resin and characterized. The kinetic parameters for β-glucosidase had apparent Km values of 0.91±0.02 and 2.84±0.05 mM and Vmax values of 5.75±0.12 and 0.71±0.01 μmol·min-1·mg of protein-1 against p-nitrophenyl-β-D-glucopyranoside and Rb1, respectively. At optimal conditions of pH 6.0 and 37°C, BglF3 could only hydrolyze the outer glucose moiety of ginsenoside Rb1 and gypenoside XVII at the C-20 position of aglycon into ginsenosides Rd and F2, respectively. These results indicate that the recombinant BglF3 could be useful for the mass production of ginsenosides Rd and F2 in the pharmaceutical or cosmetic industry.

Analysis of the LED Lamp Arrangement for Uniformity of Illumination in Indoor VLC System

Hao Hong-gang,Zhang Dan-dan,Tang Shuai 한국광학회 2014 Current Optics and Photonics Vol.18 No.6

LED lamp arrangement is a critical issue in indoor visible light communication (VLC) system. In this paper, we analyze the illumination distribution under the arrangement of 2×3 and propose a method to find the optimal lamp arrangement. The method, based on the MIMO (Multiple Input/Multiple Output) system model and taking the first order reflection into consideration, enables accurate analysis of the arrangement of the LED lamps for any room. The studies show that under the optimal arrangement the uniformity of illumination is improved from 0.55 to 0.86, which guarantees that users can get almost equal lighting effects, no matter where they locate themselves. At the same time, the RMS delay spread distribution which is used to evaluate the inter-signal-interference (ISI) is analyzed, and the simulation results indicate that the optimal arrangement also can improve the communication quality by reducing the fluctuation of the RMS delay spread.

Enzymatic Biotransformation of Ginsenoside Rb1 and Gypenoside XVII into Ginsenosides Rd and F2 by Recombinant β-glucosidase from Flavobacterium johnsoniae

Hong, Hao,Cui, Chang-Hao,Kim, Jin-Kwang,Jin, Feng-Xie,Kim, Sun-Chang,Im, Wan-Taek The Korean Society of Ginseng 2012 Journal of Ginseng Research Vol.36 No.4

This study focused on the enzymatic biotransformation of the major ginsenoside Rb1 into Rd for the mass production of minor ginsenosides using a novel recombinant ${\beta}$-glucosidase from Flavobacterium johnsoniae. The gene (bglF3) consisting of 2,235 bp (744 amino acid residues) was cloned and the recombinant enzyme overexpressed in Escherichia coli BL21(DE3) was characterized. This enzyme could transform ginsenoside Rb1 and gypenoside XVII to the ginsenosides Rd and F2, respectively. The glutathione S-transferase (GST) fused BglF3 was purified with GST-bind agarose resin and characterized. The kinetic parameters for ${\beta}$-glucosidase had apparent $K_m$ values of $0.91{\pm}0.02$ and $2.84{\pm}0.05$ mM and $V_{max}$ values of $5.75{\pm}0.12$ and $0.71{\pm}0.01{\mu}mol{\cdot}min^{-1}{\cdot}mg$ of $protein^{-1}$ against p-nitrophenyl-${\beta}$-D-glucopyranoside and Rb1, respectively. At optimal conditions of pH 6.0 and $37^{\circ}C$, BglF3 could only hydrolyze the outer glucose moiety of ginsenoside Rb1 and gypenoside XVII at the C-20 position of aglycon into ginsenosides Rd and F2, respectively. These results indicate that the recombinant BglF3 could be useful for the mass production of ginsenosides Rd and F2 in the pharmaceutical or cosmetic industry.

Hypermethylation-mediated silencing of NDRG4 promotes pancreatic ductal adenocarcinoma by regulating mitochondrial function

( Hao-hong Shi ),( Hai-e Liu ),( Xing-jing Luo ) 생화학분자생물학회(구 한국생화학분자생물학회) 2020 BMB Reports Vol.53 No.12

The N-myc downstream regulated gene (NDRG) family members are dysregulated in several tumors. Functionally, NDRGs play an important role in the malignant progression of cancer cells. However, little is known about the potential implications of NDRG4 in pancreatic ductal adenocarcinoma (PDAC). The aim of the current study was to elucidate the expression pattern of NDRG4 in PDAC and evaluate its potential cellular biological effects. Here, we firstly report that epigenetic-mediated silencing of NDRG4 promotes PDAC by regulating mitochondrial function. Data mining demonstrated that NDRG4 was significantly down-regulated in PDAC tissues and cells. PDAC patients with low NDRG4 expression showed poor prognosis. Epigenetic regulation by DNA methylation was closely associated with NDRG4 down-regulation. NDRG4 overexpression dramatically suppressed PDAC cell growth and metastasis. Further functional analysis demonstrated that up-regulated NDRG4 in SW1990 and Canpan1 cells resulted in attenuated mitochondrial function, including reduced ATP production, decreased mitochondrial membrane potential, and increased fragmented mitochondria. However, opposite results were obtained for HPNE cells with NDRG4 knockdown. These results indicate that hypermethylation-driven silencing of NDRG4 can promote PDAC by regulating mitochondrial function and that NDRG4 could be as a potential biomarker for PDAC patients. [BMB Reports 2020; 53(12): 658-663]

Developmental competence of porcine parthenogenetic embryos relative to embryonic chromosomal abnormalities

Hao, Yan-Hong,Lai, Liang-Xue,Liu, Zhong-Hua,Im, Gi-Sun,Wax, David,Samuel, Melissa,Murphy, Clifton N.,Sutovsky, Peter,Prather, Randall S. Wiley Subscription Services, Inc., A Wiley Company 2006 Molecular reproduction and development Vol.73 No.1

<P>Parthenogenetically activated (PA) embryos exhibit delayed development, a lower blastocyst rate, and less successful development in vitro compared to in vitro fertilized (IVF) embryos. To investigate the possible mechanisms for unsuccessful parthenogenetic development, this study analyzed the chromosome abnormalities and developmental potential of porcine PA embryos. Mature oocytes were electrically activated and cultured in Porcine Zygote Medium-3 (PZM<SUB>3</SUB>) supplemented with 3 mg/ml BSA for 6, 7, or 8 days. The percentage of PA blastocysts was lower than that of IVF embryos on days 6 and 7 (16.4 ± 7.4 vs. 28.7 ± 3.7; 10.9 ± 2.8 vs. 21.5 ± 4.7, P < 0.05; respectively), and the PA blastocysts had significantly fewer nuclei than IVF blastocysts (23.2 ± 1.8 vs. 29.7 ± 0.8; 29.7 ± 3.3 vs. 32.0 ± 2.4, P < 0.05). The percentage of abnormal PA embryos (including embryos with condensed nuclei, arrested embryos and fragmented embryos) was higher than that of IVF embryos (PA: 52.9 ± 12.8 vs. 16.4 ± 7.4 on day 6), and increased with culture time (71.9 ± 12.1 vs. 10.9 ± 2.8. on day 7,and 75.0 ± 22.6 vs. 12.1 ± 2.3 on day 8, P < 0.05). The Day-6 PA blastocysts (n = 147) were divided into three classes according to the total number of nuclei (<20, 20–39, >40) and into three groups according to the morphological diameter (<150, 150–180, >180 µm). Of the haploid blastocysts, 56.1% had less than 20 nuclei, and 71.5% were less than 150 µm in diameter. Of all (114) blastocysts suitable for analysis, 55.5% displayed chromosomal abnormalities. Among chromosomal abnormalities in PA blastocysts, haploid blastocysts were most prevalent (43.6%), while polyploidy (4.4%) and mixoploidy (7.7%) embryos were less prevalent. Chromosomal abnormalities of porcine PA embryos might contribute to a higher rate of abnormal embryonic development. We suggest that a careful consideration should be given when using the blastocysts with smaller size, and establishing the optimum culture condition for PA embryos development in vitro. Mol. Reprod. Dev. © 2005 Wiley-Liss, Inc.</P>

Emulsion-directed liquid/liquid interfacial fabrication of lanthanide ion-doped block copolymer composite thin films

Hong, Ming,Geng, Yuanyuan,Liu, Mei,Xu, Yuan,Lee, Yong-Ill,Hao, Jingcheng,Liu, Hong-Guo Elsevier 2015 JOURNAL OF COLLOID AND INTERFACE SCIENCE - Vol.438 No.-

<P><B>Abstract</B></P> <P>An emulsion-directed assembly and adsorption approach has been used to fabricate composite films of polystyrene-b-poly(acryl acid)-b-polystyrene (PS-b-PAA-b-PS) and Eu<SUP>3+</SUP> and La<SUP>3+</SUP> ions at the planar liquid/liquid interface of the polymer DMF/chloroform (1:1, v/v) mixed solution (lower phase) and aqueous solutions of the corresponding salts (upper phase). The lower phase gradually transformed to a water-in-oil (W/O) emulsion via spontaneous emulsification due to the “ouzo effect”. Polymer molecules and the metal ions assembled around emulsion droplets that adsorbed at the planar liquid/liquid interface at last, resulting in formation of composite films. The film morphologies and structures depend on Ln<SUP>3+</SUP> ions: polymer/Eu<SUP>3+</SUP> composite films were foam films composed of microcapsules ranging in size from several hundreds of nanometers to micrometers, while polymer/La<SUP>3+</SUP> composite films were composed of hollow spheres several tens of nanometers in size. Fourier transform infrared (FTIR) spectra revealed that the coordination modes of carboxyl groups to Eu<SUP>3+</SUP> and La<SUP>3+</SUP> were bridging bidentate and ionic, respectively, in the two types of composites. These results indicate that stable microcapsules can be fabricated around droplets for polymer/Eu<SUP>3+</SUP> systems, while microcapsules of polymer/La<SUP>3+</SUP> are unstable. This leads to different film morphologies and structures. Compositions of these films were characterized using energy-dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). In addition, foam films of polymer/Eu<SUP>3+</SUP>/2,2′-bipyridine (bpy) were fabricated using this approach, and their photoluminescence properties were investigated.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Composite films of block copolymer/Ln<SUP>3+</SUP> were fabricated at liquid/liquid interfaces. </LI> <LI> Eu<SUP>3+</SUP> and La<SUP>3+</SUP> have great effects on morphologies and microstructures of the films. </LI> <LI> Polymer/Eu<SUP>3+</SUP> and polymer/Eu<SUP>3+</SUP>/bpy films exhibit good luminescent properties. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>