Inhomogeneous Fatigue Characteristics of Welded Ti–6Al–4V Thick Plate by the Electron Beam Method

Haiyan Wang,Caiyou Zeng,Caiyou Zeng,Yupeng Zhang,Yu Zhou,Chunlin Dong 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.11

To recognize the specific safety problem brought by an increasing thickness, the layered microstructures, fatigue propertiesand the fractographies of a 100 mm-thick Ti–6Al–4V joint via electron beam welding were investigated. The results showthat the seam zone has textural and mechanical heterogeneities in the layered thickness regions. The mid layer has the lowestfatigue life and different fracture-position tendency (more broken in seam zone) due to the hybrid influences of the grain sizeand the phase fraction of α′ and β phases. The fatigue cracks initiate on the surfaces of fatigue specimens and grow in thetransgranular fracture mode. The fatigue deformation mode is adapted to the planar-slip mechanism with different degreesof dislocation blocking in distinct layers, which results in a “mid-layer favorite” crack initiation trend. Moreover, the midlayer has the highest crack propagation rate either.

Microstructure Transformation in Different Regions of Zr61.4Cu27.8Al4Ni6Y0.8 Bulk Metallic Glass Induced by Rapid Laser Welding

Haiyan Wang,Chen Yu,Wanghui Xu,Yupeng Zhang,Yanyi Ma,Yan Lin 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.12

An experimental study is performed on the microstructure transformation induced by rapid laser welding in the differentregions of Zr61.4Cu27.8Al4Ni6Y0.8bulk metallic glass (BMG). The laser input energy has a remarkable influence on themicrostructure and microhardness of the Zr-based BMGs. The microstructures in different regions of as-welded joints arediverse. Crystallization happens in heat-affected zone (HAZ) with crystalline dendritic phase of CuZr, which results in thedeterioration of the microhardness to 434.9 ± 17.1 HV in HAZ, much lower than that of parent material as 517 ± 5.0 HV. Meanwhile, the element profiles indicate that intragranular segregation of Cu element occurs during the crystallization process. In the center of molten zone (MZ), the structure is fully amorphous and its hardness is close to that of parent material. In the region transiting from MZ to HAZ, some nano-grains with an average size of 20–50 nm are identified. In addition,several flower-like nanostructured grains of Y2O3phase with a size ranging from 50 to 80 nm are formed in MZ’s matrix. The nanocrystallization is believed to be responsible for the enhancement of the Vickers hardness up to 560.1 ± 8.4 HV inthis region.

Mapping QTLs for Tissue Culture Response of Mature Wheat Embryos

Haiyan Jia,Dalong Yi,Jie Yu,Shulin Xue,Yang Xiang,Caiqin Zhang,Zhengzhi Zhang,Lixia Zhang,Zhengqiang Ma 한국분자세포생물학회 2007 Molecules and cells Vol.23 No.3

Performance of BMSC column with large eccentricity under natural exposure conditions

Haiyan Ma,Xiangchao ZENG,Hongfa Yu,Peng Yue,Haiwei Zhu,Chengyou Wu 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.76 No.4

As a new type of concrete material, basic magnesium sulfate cement concrete (BMSC) has the advantages, such as early strength, high strength, good toughness and crack resistance. However, it is unclear about the degradation of the mechanical properties of BMSC columns, which is exposed to the natural environment for several years. In order to apply this new concrete to practical engineering, six large-eccentricity compressive columns of BMSC were studied. The mechanical properties such as the crack propagation, failure morphology, lateral displacement and bearing capacity of BMSC column were studied. The results show that the degradation rate of ultimate load of BMSC column is from 6% to 7%. The degradation rate of the stiffness of the column is from 6% to 13%. With the increase of compressive strength of BMSC, the axial displacement and lateral displacement are gradually reduced. The calculation model of bearing capacity of the BMSC column under the large eccentric compression is proposed. This paper provides a reference for the application of BMSC columns in the civil engineering.

Efficient complete oxidation of acetaldehyde into CO2 over Au/TiO2 core-shell nano catalyst under UV and visible light irradiation.

Song, Haiyan,Yu, Yeon-Tea,Norby, Poul American Scientific Publishers 2009 Journal of Nanoscience and Nanotechnology Vol.9 No.10

<P>Photocatalytic degradation of acetaldehyde and its photocatalytic mechanisms over Au/TiO2 core-shell nano catalyst were, for the first time, investigated under UV and visible light irradiation. The results indicate that Au/TiO2 core-shell catalyst shows higher activity for the oxidation of acetaldehyde into CO2 under both UV and visible light irradiation comparing with P-25 and metal-deposited TiO2 photocatalysts. When Au/TiO2 core-shell catalyst is excited by UV light, the Au-core acts as the sink to restore the separated electrons, thus to improve the photoinduced charge separation; while under visible light irradiation, the mechanism can be understood as the coordinate effect of the plasmon resonance of Au-core particles and the formation of an impurity energy level induced by TiO(2-x)F(x).</P>

Neuroprotection of Dexmedetomidine against Cerebral Ischemia-Reperfusion Injury in Rats: Involved in Inhibition of NF-κB and Inflammation Response

( Lijun Wang ),( Haiyan Liu ),( Ligong Zhang ),( Gongming Wang ),( Mengyuan Zhang ),( Yonghui Yu ) 한국응용약물학회 2017 Biomolecules & Therapeutics(구 응용약물학회지) Vol.25 No.4

Dexmedetomidine is an α2-adrenergic receptor agonist that exhibits a protective effect on ischemia-reperfusion injury of the heart, kidney, and other organs. In the present study, we examined the neuroprotective action and potential mechanisms of dexmedetomidine against ischemia-reperfusion induced cerebral injury. Transient focal cerebral ischemia-reperfusion injury was induced in Sprague-Dawley rats by middle cerebral artery occlusion. After the ischemic insult, animals then received intravenous dexmedetomidine of 1 mg/kg load dose, followed by 0.05 mg/kg/min infusion for 2 h. After 24 h of reperfusion, neurological function, brain edema, and the morphology of the hippocampal CA1 region were evaluated. The levels and mRNA expressions of interleukin-1b, interleukin-6 and tumor nevrosis factor-α as well as the protein expression of inducible nitric oxide synthase, cyclooxygenase-2, nuclear factor-κBp65, inhibitor of κBα and phosphorylated of κBα in hippocampus were assessed. We found that dexmedetomidine reduced focal cerebral ischemia-reperfusion injury in rats by inhibiting the expression and release of inflammatory cytokines and mediators. Inhibition of the nuclear factor-κB pathway may be a mechanism underlying the neuroprotective action of dexmedetomidine against focal cerebral I/R injury.

A study of the behavior of MUA-coated Au colloid in ethanol solution

Yeon-Tae Yu,Haiyan Song,Young-Min Lim,Hyun-Woo Kwon,Min-Sang Lee 한양대학교 세라믹연구소 2007 Journal of Ceramic Processing Research Vol.8 No.5

A stable gold colloid dispersed in ethanol solution was prepared by coating with MUA. The stability of MUA-gold particles in the ethanol solution was studied using UV-Vis absorption spectra, which were affected by the MUA concentration, water concentration, initial particle size of the gold and heat treatment. A stable MUA-gold colloid in ethanol was obtained when the concentrations of MUA and water were 0.02 mM and 16.7 M, respectively. The small sizes of the gold particles before encapsulation and a low temperature were preferable for the stability of MUA-gold particles in the ethanol solution. A stable gold colloid dispersed in ethanol solution was prepared by coating with MUA. The stability of MUA-gold particles in the ethanol solution was studied using UV-Vis absorption spectra, which were affected by the MUA concentration, water concentration, initial particle size of the gold and heat treatment. A stable MUA-gold colloid in ethanol was obtained when the concentrations of MUA and water were 0.02 mM and 16.7 M, respectively. The small sizes of the gold particles before encapsulation and a low temperature were preferable for the stability of MUA-gold particles in the ethanol solution.

Conceptional design of an adjustable moderator for BNCT based on a neutron source of 2.8 MeV proton bombarding with Li target

Zhu Yinan,Lin Zuokang,Yu Haiyan,Yu Xiaohan,Dai Zhimin 한국원자력학회 2024 Nuclear Engineering and Technology Vol.56 No.5

Beam shaping assembly (BSA) is a vital component in Boron Neutron Capture Therapy (BNCT) for obtaining epithermal neutron beams. Several feasible designs of BSA for accelerator-based BNCT (AB-BNCT) neutron source are carried out based on neutrons by bombarding a natural lithium target with 10 mA, 2.8 MeV proton beams. The calculation results demonstrate that a thickness of 45 cm is appropriate for general moderators referring to the therapeutic parameter of Advanced Depth (AD). A series of optimizations are performed and two results are confirmed: One is that employing the configuration of MgF2 and FLUENTAL combined by 1:1 could improve the therapeutic rate (TR) of tumors at a depth of middle region, and the other one is that the TR of superficial tumors can be increased by adding a 5 cm thick boron-11 secondary moderator at the end of general moderators. As a result, an innovative conception of an adjustable moderator is recommended to BNCT. Compared to the MgF2 moderator with a fixed thickness of 45 cm, the TR value can be improved by a maximum of 47.7 % by using the adjustable moderator. Furthermore, the configuration of adjustable moderator has been designed with regulation method for treating tumors of different depths.

A comparative study on defluoridation capabilities of biosorbents: Isotherm, kinetics, thermodynamics, cost estimation and regeneration study

Endashaw Workie Yihunu,Haiyan Yu,Wen Junhe,Zhang Kai,Zebene Lakew Teffera,Brhane Weldegebrial,Ma Limin 대한환경공학회 2020 Environmental Engineering Research Vol.25 No.3

The presence of high fluoride concentration (> 1.5 mg/L) in water causes serious health problems such as fluorosis, infertility, brain damage, etc., which are endemic to many places in the world. This study has investigated the fluoride removal capacity of the novel activated biochar (BTS) and hydrochar (HTS) using Teff (Eragrostis tef) straw as a precursor. Activated biochar with mesoporous structures and large specific surface area of 627.7 ㎡/g were prepared via pyrolysis process. Low-cost carbonaceous hydrochar were also synthesized by an acid assisted hydrothermal carbonization process. Results obtained from both adsorbents show that the best local maximum fluoride removal was achieved at pH 2, contact time 120 min and agitation speed 200 rpm. The thermodynamic studies proved that the adsorption process was spontaneous and exothermic in nature. Both adsorbents equilibrium data fitted to Langmuir isotherm. However, Freundlich isotherm fitted best for BTS. The maximum fluoride loading capacity of BTS and HTS was found to be 212 and 88.7 mg/g, respectively. The variation could primarily be attributed to a relatively larger Surface area for BTS. Hence, to treat fluoride contaminated water, BTS can be promising as an effective adsorbent.

A prevalence survey of Wolbachia in Polytremis fukia (Lepidoptera: Hesperiidae)

Weibin Jiang,Yajuan Wu,Haiyan He,Jianqing Zhu,Weidong Yu 한국응용곤충학회 2016 Journal of Asia-Pacific Entomology Vol.19 No.2

Wolbachia are endosymbiotic bacteria that infect arthropod and nematode hosts. Only a few studies have been made on Wolbachia in butterflies. In this study, we identified and determined the molecular characteristics of Wolbachia strains in Polytremis fukia (Lepidoptera: Hesperiidae), from seven locations in China. We also sequenced three portions of the mitochondrial DNA from the individuals of P. fukia to infer the effect of Wolbachia on host mitochondrial variation. The results show that 47% (15/32) are Wolbachia positive among all specimens. The infection rates in female and male are 69% (11/16) and 25% (4/16). Phylogenetic analysis of variation in the ftsZ gene from the two strains of Wolbachia (wFuk1 and wFuk2) showed they belonged to supergroup A. On the phylogeny of the mitochondrialDNA fromP. fukia, the sequences are split into three clades. Clade I and II are consistent with the distribution of geographical population. Clade III consists of eight females invariably infected with wFuk1which showed aweak association existed between mitochondrial DNA haplotypes andwFuk1 infection status.