Long-range and short-range orders, and phase miscibility of CoCrPt/Ti thin films

Ph.DDOCTOR OF PHILOSOPH

A study of biomarker analysis in association with type 1 diabetes and their shared features in rheumatoid arthritis

Type 1 diabetes (T1D) is mediated by abnormal immune system (autoimmunity) that targeting specifically to self insulin-producing cells (β-cells). People with T1D require treatments based on life-long insulin substitution. In addition to the damages in health caused by T1D complications, the complexity of insulin treatment and the fear of glucose dysregulation often place extra burden to the affected family. There is a current need for better understanding of the disease etiology therefore guide the construction of successful prediction and prevention strategies for the disease. There are many immune-related genes playing important roles in T1D etiology. In addition, there is a trend of autoimmune diseases segregating within individuals and families where those genes are critically involved. Exploration of these genes can provide knowledge related to the disease pathogenesis. In my studies, we select two genes functioning in the immune system and explored their potential roles in T1D. In addition, we analyzed the association between HLA alleles and T1D autoimmune markers (autoantibodies) in rheumatoid arthritis patients. Killer cell immunoglobulin like receptors (KIRs) is a group of receptors expressed on the surface of natural killer cells and subgroups of T cells. KIRs could accelerate autoimmune diabetes in rodent models. However their roles in human T1D are not clear. In Study I, we studied the T1D association of KIR genes and their combination with HLA-C ligand genes in Chinese Han population. Our results indicated that KIR modifies the T1D association of HLA-C ligand genes. Recent studies indicated that KIRs exert their function in a collective fashion and their effects can initiate as early as life in uterus by maternal-fetal interaction. Therefore in Study II, we studied the T1D association with the collection of maternal KIR genes and their combination with fetal HLA-C ligand genes in the Chinese Han population. Results from study II indicated that the accumulation of maternal activating KIRs along with fetal HLA-C2 genes predispose T1D in the fetus. Alpha-B crystallin (encoded by CRYAB) is a major autoimmune target in multiple sclerosis (an autoimmune disease occurred in central nervous system). In Study III, we tested the association between CRYAB gene and islet autoantibodies in T1D using two well-established Swedish cohorts. Our results suggested that genetic variant in the promoter region of CRYAB is associated with increased T1D risk and islet autoantibodies in T1D patients. In Study IV, we aimed to identify genetic factors that cause the aggregation of the two autoimmune disorders, T1D and rheumatoid arthritis (RA). We measured islet autoantibodies among RA patients and analyzed the association between HLA and islet autoantibodies in RA patients and in subgroups of RA positive for anti-citrullinated protein antibodies. We identified that HLA DR4 alleles were associated with increased islet autoantibodies in RA patients, however HLA DR3 alleles were the major genetic contributors toward elevated islet autoantibodies among RA patients positive for both anti-CCP and anti-CEP-1. In conclusion, our studies indicated that KIR, CRYAB are among the genetic factors predisposing T1D. In addition, HLA alleles are the major contributors to the presence of islet autoantibodies among RA patients

New Yellow Ba\u3csub\u3e0.93\u3c/sub\u3eEu\u3csub\u3e0.07\u3c/sub\u3eAl\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e4\u3c/sub\u3e

Phosphor-converted white light-emitting diodes for indoor illumination need to be warm-white (i.e., correlated color temperature \u3c4000 \u3eK) with good color rendition (i.e., color rendering index \u3e80). However, no single-phosphor, single-emitting-center-converted white light-emitting diodes can simultaneously satisfy the color temperature and rendition requirements due to the lack of sufficient red spectral component in the phosphors’ emission spectrum. Here, we report a new yellow Ba0.93Eu0.07Al2O4phosphor that has a new orthorhombic lattice structure and exhibits a broad yellow photoluminescence band with sufficient red spectral component. Warm-white emissions with correlated color temperature 80 were readily achieved when combining the Ba0.93Eu0.07Al2O4 phosphor with a blue light-emitting diode (440–470 nm). This study demonstrates that warm-white light-emitting diodes with high color rendition (i.e., color rendering index \u3e80) can be achieved based on single-phosphor, single-emitting-center conversion

An electromagnetic coupling treatment for improving the cutting performance of cemented carbide-coated tools

To improve the cutting performance and prolong the service life of a carbide-coated tool in the process of ductile iron machining, an electromagnetic coupling treatment (EMCT) was carried out. The cutting experiments show that the cutting force and cutting temperature are reduced after EMCT, and the roughness of the machined surface is reduced. It is found that after EMCT with optimal parameters the dislocation density, microscopic strain, microhardness and bonding strength of an alumina coating increase by 109.2%, 28.2%, 28.3% and 26.6%, respectively. Using the actual machining of a differential housing to verify the tool life, it is found that after EMCT, a single tool can process 18.4 more workpieces or in other words, the tool life increased by 44%. EMCT can promote element diffusion, optimize coating properties and have great potential in coating tool life extension

Opposite effects of Co and Cu dopants on the catalytic activities of birnessite MnO2 catalyst for low-temperature formaldehyde oxidation

Defect engineering is an effective strategy to enhance the activity of catalysts for various applications. Herein, it was demonstrated that in addition to enhancing surface properties via doping, the influence of dopants on the surface-intermediate interaction is a critical parameter that impacts the catalytic activity of doped catalysts for low-temperature formaldehyde (HCHO) oxidation. The incorporation of Co into the lattice structure of δ-MnO2 led to the generation of oxygen vacancies, which promoted the formation of surface active oxygen species, reduced activation energy, and enhanced catalytic activity for low-temperature oxidation of HCHO. On the contrary, Cu doping led to a drastic suppression of the catalytic activity of δ-MnO2, despite its enhanced redox properties and slight increase in the surface concentration of active oxygen species, compared to pristine δ-MnO2. Diffuse reflectance infrared Fourier transform analysis revealed that in the presence of Cu, carbonate intermediate species accumulate on the surface of the catalysts, leading to partial blockage of active sites and suppression of catalytic activity

The performance of large-pitch AC-LGAD with different N+ dose

AC-Coupled LGAD (AC-LGAD) is a new 4D detector developed based on the Low Gain Avalanche Diode (LGAD) technology, which can accurately measure the time and spatial information of particles. Institute of High Energy Physics (IHEP) designed a large-size AC-LGAD with a pitch of 2000 {\mu}m and AC pad of 1000 {\mu}m, and explored the effect of N+ layer dose on the spatial resolution and time resolution. The spatial resolution varied from 32.7 {\mu}m to 15.1 {\mu}m depending on N+ dose. The time resolution does not change significantly at different N+ doses, which is about 15-17 ps. AC-LGAD with a low N+ dose has a large attenuation factor and better spatial resolution. Large signal attenuation factor and low noise level are beneficial to improve the spatial resolution of the AC-LGAD sensor

Characterization of the response of IHEP-IME LGAD with shallow carbon to Gamma Irradiation

Low Gain Avalanche Detectors (LGAD), as part of High-Granularity Timing Detector (HGTD), is crucial to reducing pileup in the upgrading to HL-LHC. Many studies have been done on the bulk damages of the LGAD. However, there's no study about the surface radiation hardness of the LGAD sensors with carbon implanted. The IHEP-IME LGAD version 3 with the shallow carbon and different interpad separations were irradiated up to 2 MGy by gamma irradiation. The performance of the IHEP-IME LGAD version 3 before and after irradiation had been tested, such as the leakage current, break-down voltage, capacitance, V$_{gl}$, and inter-pad resistance. The results showed that apart from minor fluctuations in some samples, no significant changes concerning inter-pad separation were observed before and after irradiation. Leakage current and break-down voltage increase after irradiation, which is considered due to surface passivation; the overall inter-pad resistance are larger than $10^9\ \Omega$before and after irradiation; capacitance is found to be less than 4.5 pF with a slight drop in V$_{gl}$ after irradiation. All parameters meet the requirements of HGTD, and the results indicated that IHEP-IME LGAD v3 has excellent anti-irradiation performance

Characterisation of Spatial and Timing Resolution of IHEP AC-LGAD Strip

AC-coupled LGAD(AC-LGAD) Strip is a new design of LGAD that allows high-precision detection of particle spatiotemporal information whereas reducing the density of readout electronics. For AC-LGAD Strips, there is limited research on the impact of different strip pitches on the spatiotemporal detection performance at the small amount of injected charge. The Institute of High Energy Physics has designed an AC-LGAD Strip prototype with pitches of 150 $\mu m$, 200 $\mu m$, and 250 $\mu m$. The spatial and timing resolutions of the prototype are studied through the laser Transient Current Technique (TCT) scan with different amounts of injected charge. The results show that both the spatial and timing resolution improves as the strip pitch decreases. Increases in both temporal and spatial resolutions as the amount of charge injected increases are observed. The spatial and timing resolution is better than 60 ps and 40 $\mu m$ at 1 Minimum Ionizing Particle (MIP), and better than 10 ps and 5 $\mu m$ at 40 MIPs. Increasing Signal-to-Noise Ratio (SNR) is the key to improving spatial and temporal resolution, whereas increasing the signal attenuation rate by reducing the gap between adjacent electrodes also helps to improve spatial resolution. The enhancements of spatial and timing resolutions by both SNR and signal attenuation rate decrease with increasing amount of MIP. This study can help design and optimize the AC-LGAD Strip detectors and readout electronics

Exfoliation of two-dimensional phosphorene sheets with enhanced photocatalytic activity under simulated sunlight

Two-dimensional phosphorene (2D-BP) nanosheets were successfully prepared by an environmental friendly water exfoliation process. The morphology and structure of exfoliated 2D-BP nanosheets were characterized by SEM, AFM, Raman and UV–Vis. The photocatalytic results demonstrated that 2D-BP nanasheets can generate reactive oxygen species of 1O2 and O2− and effectively enhance the photodegradation of dibutyl phthalate pollutants when coexist with water, oxygen, and light