Effect of Prior Microstructures on Cementite Dissolution Behavior During Subcritical Annealing of High Carbon Steels

Xiao‑Yu Zhao,Xian‑Ming Zhao,Chun‑Yu Dong,Yang Yang,Huai‑Bin Han 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.6

The variation of the morphology and distribution of cementite particles in different prior structures with spheroidizingannealing process has been proceeded in this paper. It is found that the dissolution and coarsening progresses of variousinitial structures in spheroidizing annealing process are quite asynchronous due to the different interlamellar spacing. Thedissolution rate of degenerated pearlite (D-P) with finer interlamellar spacing is faster. The granular cementite in the spheroidizedmicrostructure is fine, uniform and dense. The mean diameter of spherical cementite is refined to 233 nm. However,the initial structure of degenerated pearlite (D-P) is highly sensitive to the austenitization temperature. The cementite iseasy to be coarsened under high austenitizing temperature. The coarsening is accompanied by the gradual increase of theCr content in the cementite, which increases the stability of the cementite. Therefore, the optimal austenitizing temperaturefor degenerated pearlite (D-P) is suggested to be 770 °C.

Transcriptome profiling of rubber tree (Hevea brasiliensis) discovers candidate regulators of the cold stress respo

Xiao‑Xiao Gong,Bing‑Yu Yan,Jin Hu,Cui‑Ping Yang,Yi‑Jian Li,Jin‑Ping Liu,Wen‑Bin Liao 한국유전학회 2018 Genes & Genomics Vol.40 No.11

Tropical plant rubber tree (Hevea brasiliensis) is the sole source of commercial natural rubber and low-temperature stress is the most important limiting factor for its cultivation. To characterize the gene expression profiles of H. brasiliensis under the cold stress and discover the key cold stress-induced genes. Three cDNA libraries, CT (control), LT2 (cold treatment at 4 °C for 2 h) and LT24 (cold treatment at 4 °C for 24 h) were constructed for RNA sequencing (RNA-Seq) and gene expression profiling. Quantitative real time PCR (qRT-PCR) was conducted to validate the RNA-Seq and gene differentially expression results. A total of 1457 and 2328 differentially expressed genes (DEGs) in LT2 and LT24 compared with CT were respectively detected. Most significantly enriched KEGG pathways included flavonoid biosynthesis, phenylpropanoid biosynthesis, plant hormone signal transduction, cutin, suberine and wax biosynthesis, Pentose and glucuronate interconversions, phenylalanine metabolism and starch and sucrose metabolism. A total of 239 transcription factors (TFs) were differentially expressed following 2 h or/and 24 h of cold treatment. Cold-response transcription factor families included ARR-B, B3, BES1, bHLH, C2H, CO-like, Dof, ERF, FAR1, G2-like, GRAS, GRF, HD-ZIP, HSF, LBD, MIKC-MADS, M-type MADS, MYB, MYB-related, NAC, RAV, SRS, TALE, TCP, Trihelix, WOX, WRKY, YABBY and ZF-HD. The genome-wide transcriptional response of rubber tree to the cold treatments were determined and a large number of DEGs were characterized including 239 transcription factors, providing important clues for further elucidation of the mechanisms of cold stress responses in rubber tree.

Effect of Different Cooling Rates in High Rheological Rate Forming Process on Mechanical Properties of Zr57Cu20Al10Ni8Ag5 Bulk Metallic Glass

Xiao‑Bo Mei,Bao‑Chuan Liu,Wei Jiang,Quan Xu,Qi‑Dong Zhang,Yu‑Bai Ma,Fang‑Qiu Zu 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.9

The influence of cooling rates on the mechanical properties of a Zr-based bulk metallic glass prepared with high rheologicalrate forming (HRRF) was investigated and compared with traditional suction cast methods. Amorphous samples of Zr57Cu-20Ni8Al10Ag5 were prepared in copper molds with different sizes in order to obtain different cooling rates for both HRRFand traditional cast methods. These specimens were subjected to compression experiments, including microhardness testing,X-ray diffraction testing and differential scanning calorimetry analysis. The results indicate that the plasticity of the samplesformed by HRRF are higher than that of the as-cast ones at the same cooling rates, while the microhardness manifests theopposite principle. As the cooling rate increases further, the difference in plasticity further increases between two methods,indicating that the plasticity of metallic glasses is more sensitive to cooling rates during the HRRF process. At the core ofthis phenomenon is the fact that HRRF methods can introduce more free volume into glasses than traditional cast methodswith an elevated cooling rate are able to.

Preparation and Electrochemical Performances of Rod-Like LiV3O8/Carbon Composites Using Polyaniline as Carbon Source

Xiao-Yu Cao,Limin Zhu,Hailian Wu 대한금속·재료학회 2015 ELECTRONIC MATERIALS LETTERS Vol.11 No.4

Rod-like LiV3O8/carbon composites were successfully prepared by the polymer graphitization of LiV3O8/polyaniline composites, which were synthesized through the in-situ oxidative polymerization method. The crystal phases of as-prepared samples, confirmed by X-ray diffraction, show that the interlayer spacing in LiV3O8/ carbon composites is much wider than that of the pristine LiV3O8. Compared to the bare LiV3O8, the longer and smoother rod-like LiV3O8/carbon composites, investigated by scanning electron microscope and transmission electron microscope, were covered by a continuously thin layer of fluffy carbon with a thickness of approximate 20 nm. The optimal LiV3O8/carbon composite delivered a discharge capacity of 219.37 mAh g−1 in the initial cycle, and maintained a high capacity of 263.538 mAh g−1 at the 30th cycle, which was much higher than that of the pristine LiV3O8 (227.645 mAh g−1). Cyclic voltammetry measurements disclose that, after the carbon coating treatment, the phase transition of the optimal LiV3O8/carbon composite proceeds more reversibly and smoothly during charging/discharging. The improved cyclability of the optimal LiV3O8/carbon composite should be attributed to the confinement from thin carbon layer, the structural stability, the good interfacial compatibility, and the well-preserved electrode morphology after prolonged cycles.

Theoretical Analysis and Optimization of Extrinsic Fabry-Perot Interferometer Optical-fiber Humidity-sensor Structures

Xiao Lei Yin,Ning Wang,Xiao Dan Yu,Yu Hao Li,Bo Zhang,Dai Lin Li 한국광학회 2021 Current Optics and Photonics Vol.5 No.6

The theoretical analysis and optimization of extrinsic Fabry-Perot interferometer (EFPI) opticalfiber humidity sensors are deeply investigated. For a typical dual-cavity structure composed of an optical fiber and a humidity-sensitive membrane (HSM), the changes in refractive index (RI) and initial length are discussed for polymer materials and porous oxide materials when relative humidity (RH) increases. The typical interference spectrum is simulated at different RH using MATLAB. The spectral change caused by changing HSM RI and initial length are simulated simutineously, showing different influences on humidity response. To deeply investigate the influence on RH sensitivity, the typical response sensitivity curves for different HSM lengths and air-cavity lengths are simulated. The results show that the HSM is the vital factor. Short HSM length can improve the sensitivity, but for HSM RI and length the influences on sensitivity are opposite, because of the opposite spectral-shift trend. Deep discussion and an optimization method are provided to solve this problem. According to analysis, an opaque HSM is helpful to improve sensitivity. Furthermore, if using an opaque HSM, a short air cavity and long HSM length can improve the sensor’s sensitivity These results provide deep understanding and some ideas for designing and optimizing highly sensitive EFPI fiber humidity sensors.

The biochemical effects of Microcystis on common carp (Cyprinus carpio)

( Xiao Yu Li ),( Jung In Kim ),( Jin Ae Lee ) 대한상하수도학회 2003 공동추계 학술발표회 논문집 Vol.2003 No.-

Improvement of Tautomycin Production in Streptomyces spiroverticillatus by Feeding Glucose and Maleic Anhydride

Xiao-Long Chen,Yu-Hua Xu,Yu-Guo Zheng,Yin-Chu Shen 한국생물공학회 2010 Biotechnology and Bioprocess Engineering Vol.15 No.6

Optimization of the feeding process for tautomycin production by Streptomyces spiroverticillatus was performed using glucose and/or maleic anhydride. The feeding of glucose was based on the reducing sugar content (lower than 8 g/L) at a cultivation time of 40 h. After addition of 2% (w/v) glucose, the biomass increased from 21 to 28 g/L, and that of tautomycin from 572.06 to 837.6mg/L. Moreover, 1723.1 mg/L of tautomycin (increased by 201.21%) was obtained by feeding 0.2% (w/v) maleic anhydride solution at a pH between 4 and 7 in the broth. For the experiments in the 15 L fermentor, tautomycin content reached its highest level (1714.7 mg/L), which was 199.7% higher than that of control by feeding both glucose and maleic anhydride.

The Changes of Hormonal Contents in Seed Germination of Herbaceous Peonies (Peaonia veitchii)

Yu Xiao Nan 한국원예학회 2006 한국원예학회 기타간행물 Vol.- No.-

Porous Carbon Particles Derived from Natural Peanut Shells as Lithium Ion Battery Anode and Its Electrochemical Properties

Xiao-Yu Cao,Shuangqiang Chen,왕과시우 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.4

Abandoned peanut shells, a common farm waste, have caused tremendous environmental pollution and huge waste deposits through burned and buried disposal approaches. In targeting to enhance the potential value of peanut shells and discover a new alternative candidate for lithium ion batteries, we adopted an easy to scale-up and highly repeated method to treat fresh and dry peanut shells via acid-treatment and pyrolysis, making porous structures on carbonized peanut shells. The pyrolysis process transformed the peanut shells to porous carbon (PC) materials in a quartz tube furnace at a series of temperatures from 500°C to 700°C in N2 under the condition of 40°C gradient temperatures with a heating rate of 2°C min−1. Scanning electron microscopy (SEM) images show that the irregular porous structures and hundreds of micropores are distributed on the PC materials. The cyclic voltammogram (CV) test and particle size analysis are employed to investigate their characteristics of voltammetry and particle size distribution. PC material obtained at 620°C (PC-620) exhibited good particle distribution, porous structure and less agglomerated particles. When applied as anode materials in lithium ion batteries, the PC-620 electrode displayed the high reversible capacity of 608 mAh g–1. Moreover, the cycling performance of PC-620 was the most stable, with a high Coulombic efficiency of 98.9% at the 20th cycle, demonstrating a reversible capacity of 418 mAh g–1, which is higher than the theoretical capacity of graphite. Most importantly, the PC materials harvested from the wastes of natural resources are turned into valuable electrode materials for the high demand energy storage devices, which can significantly reduce severe environmental pollution and alleviate an energy shortage.

Wide-Tunable Mid Infrared Intra-cavity Optical Parametric Oscillator Based on Multi-period MgO:PPLN

Xiao-Chan Wang,Yu-Heng Wang,Hao Zheng,Hong-Zhi Liu,Yong-Ji Yu,Zi-Jian Wang 한국광학회 2021 Current Optics and Photonics Vol.5 No.1

This paper reports a tunable diode-pumped folded intracavity Q-switched singly resonant optical parametric oscillator based on multi-period MgO:PPLN. A wide tuning mid-infrared parametric lightfrom 2.78 μm to 4.17 μm was obtained in real time by changing the poled periods and temperatures. The maximum output power of 1.89 W at 3.2 μm, 1.53 W at 3.5 μm, 0.87 W at 3.8 μm and 0.486 W at 4.1 μm were achieved. The highest optical-optical conversion efficiency was 7.89%. During experiments, a range tunable output of 2.78–4.17 μm in the mid-infrared range was achieved.