Beijing University of Technology

About: Beijing University of Technology is a education organization based out in Beijing, Beijing, China. It is known for research contribution in the topics: Microstructure & Laser. The organization has 31929 authors who have published 31987 publications receiving 352112 citations. The organization is also known as: Běijīng Gōngyè Dàxué & Beijing Polytechnic University.

Overview of Tyrosine Hydroxylase in Parkinson’s Disease

Abstract: Tyrosine hydroxylase (TH) is the rate-limiting enzyme in brain catecholamine biosynthesis, and tetrahydrobiopterin is its cofactor. Research has focused on identifying mechanisms of TH activity regulation. TH activity is modulated by the cofactor itself, and is enhanced by several kinases phosphorylating key serines in the TH regulatory domain. Aside from these, the mechanisms that control TH gene transcription and TH mRNA translation are also related with the regulation of TH activity. Parkinson’s disease (PD) is characterized by severe loss of dopaminergic neurons and depletion of dopamine in substantia nigra. Reduction of TH expression results in diminished dopamine synthesis and leads to PD; thus TH is essential in the pathogenesy of PD. It has also been shown that dysregulation of TH activity will contribute to PD. For example, α-synuclein represses TH not only by inhibiting phosphorylation at Ser40 of TH, but also by stimulating protein phosphatase 2A activity, which decreases dopamine synthesis and leads to parkinsonism. Based on these studies of TH in PD pathogenesis, a therapeutic strategy aimed to improve striatal TH expression in PD has received wide interest. Evidence shows that using drugs or other treatment methods such as gene replacement therapy to increase nigrostriatal TH expression is an effective therapy for PD. Further investigation of TH regulatory mechanisms will not only provide additional drug targets for PD, but may also help to identify new PD therapeutics.

Laser cladding in-situ NbC particle reinforced Fe-based composite coatings with rare earth oxide addition

Abstract: Over the past decade, researchers have demonstrated much interest in laser cladded metal matrix composite coatings for its good wear resistance, corrosion resistance and high temperature properties. The effects of RE on the microstructure and properties of laser coatings have also got more and more attention. In this paper, in situ Fe-NbC composite coatings with different CeO2 addition were produced on die steel by laser cladding. The formation mechanism of NbC particles was analyzed. The effects of RE on microstructure and micro-hardness of coatings were investigated. It was revealed that larger NbC particles with hard edges formed around Nb particles, and smaller flocculent NbC particles formed by the chemical reaction of Nb and solid graphite in the molten pool. CeO2 plays important roles in reducing micro-porosities, refining grains, and improving the precipitation of NbC. Therefore, the average micro-hardness and its smoothness from the top to the bottom of the coating were improved after adding CeO2.

Synthesis, Characterization and Spectral Properties of Substituted Tetraphenylporphyrin Iron Chloride Complexes

Abstract: A series of substituted tetraphenylporphyrin iron chloride complexes [RTPPFe(III)Cl, R=o/p-NO₂, o/p-Cl, H, o/p-CH₃, o/p-OCH₃] were synthesized by a novel universal mixed-solvent method and the spectral properties of free base porphyrins and iron porphyrin compounds were compared with each other. The experimental results showed that the one-pot mixed solvent method was superior to the two-step method in the yields, reaction time and workup of reaction mixtures for the synthesis of iron porphyrin compounds. The highest yields (28.7%-40.4%) of RTPPFe(III)Cl were obtained in the mixed solvents propionic acid, glacial acetic acid and m-nitrotoluene under reflux for 2 h. A detailed analysis of ultraviolet-visible (UV-vis), infrared (IR) and far-infrared (FIR) spectra suggested the transformation from free base porphyrins to iron porphyrins. The red shift of the Soret band in ultraviolet-visible spectra due to the presence of p-nitrophenyl substituents and the blue shift of Fe-Cl bond of TPPFeCl in far-infrared spectra were further explained by the electron transfer and molecular planarity in the porphyrin ring.