基于调频信号发射的超声造影剂谐波成像方法

提出了一种能够提取超声造影剂回波中二次谐波的非线性成像方法,从数学原理、仿真计算和声学实验三个方面对造影剂血流灌注成像方法进行了研究。首次将调频信号发射技术用于医学超声造影剂谐波成像领域,仿真计算和声学实验结果表明:为了获得较好的图像质量,发射调频信号应该具有合适的包络;发射信号带宽与解码匹配滤波器带宽之间必须有一个带宽间隔;适当降低发射声压能够降低生物组织的谐波。应用编码发射方法和解码滤波器,得到了造影剂二次谐波图像,此图像具有较好的信号噪声比和造影剂组织比。声学实验结果和理论计算结果完全吻合。     

Wittig反应的研究——Ⅳ.苹果蠹蛾性信息素E,E-8,10-十二碳二烯-1-醇立体选择性的合成

通过二苯基烯丙基型叶立德与8-氧辛酸甲酯进行的Wittig反应,合成苹果蠹蛾性信息素,E,E-8,10-十二碳二烯-1-醇(5)。这个反应的特点是反式选择性高,产物中E,E-异构体的含量可达95%以上。     

CHIP-mediated hyperubiquitylation of tau promotes its self-assembly into the insoluble tau filaments

The tau protein is a highly soluble and natively unfolded protein. Under pathological conditions, tau undergoes multiple post-translational modifications (PTMs) and conformational changes to form insoluble filaments, which are the proteinaceous signatures of tauopathies. To dissect the crosstalk among tau PTMs during the aggregation process, we phosphorylated and ubiquitylated recombinant tau in vitro using GSK3β and CHIP, respectively. The resulting phospho–ub-tau contained conventional polyubiquitin chains with lysine 48 linkages, sufficient for proteasomal degradation, whereas unphosphorylated ub-tau species retained only one–three ubiquitin moieties. Mass-spectrometric analysis of in vitro reconstituted phospho–ub-tau revealed seven additional ubiquitylation sites, some of which are known to stabilize tau protofilament stacking in the human brain with tauopathy. When the ubiquitylation reaction was prolonged, phospho–ub-tau transformed into insoluble hyperubiquitylated tau species featuring fibrillar morphology and in vitro seeding activity. We developed a small-molecule inhibitor of CHIP through biophysical screening; this effectively suppressed tau ubiquitylation in vitro and delayed its aggregation in cultured cells including primary cultured neurons. Our biochemical findings point to a “multiple-hit model,” where sequential events of tau phosphorylation and hyperubiquitylation function as a key driver of the fibrillization process, thus indicating that targeting tau ubiquitylation may be an effective strategy to alleviate the course of tauopathies.

Multiple-hit model for tau aggregation, where sequential events of tau phosphorylation and hyperubiquitylation function as a key driver of the fibrillization process.     

Radiation grafting from binary monomer mixtures. I. Vinyl ether of monoethanolamine and vinyl ether of ethyleneglycol

Gamma-radiation grafting of vinyl ether of monoethanolamine and vinyl ether of ethyleneglycol (VEEG) on polyethylene films has been studied from binary monomer mixtures. The effect of co-monomer composition and total exposure radiation dose on the grafting process is investigated. A combination of potentiometric and gravimetric techniques is applied to determine the grafting degree of each monomer in the final graft copolymer. The presence of more active monomer VEEG in the mixture was found to enhance the grafting of both monomers because the increasing of copolymerization rate which in turn increases the total grafting degree. The modification of the hydrophilic properties of the graft copolymer is studied by examining the grafted films for water- and copper (II) ions uptake.     

Swelling behavior of amphiphilic hydrogels of copolymers of the vinyl ether of ethylene glycol and vinyl isobutyl ether,and their interaction with cationic surfactant

Amphiphilic hydrogels of copolymers of the vinyl ether of ethylene glycol and vinyl isobutyl ether were synthesized by -radiation-induced free radical polymerization. Hydrogels with certain copolymer compositions showed thermo-sensitive behavior in aqueous solutions. The swelling behavior of the hydrogels in cetylpyridinium bromide aqueous solution was studied. Increased swelling of the hydrogels was observed in the surfactant solutions. The increased swelling was more prominent for the hydrogels with a higher content of hydrophobic moiety in the copolymer composition, and with higher surfactant concentration. The reason for this phenomenon is discussed. Treatment of some hydrogels in the surfactant solutions resulted in higher swelling ability in distilled water with distinct thermo-induced contraction over a narrow temperature interval.     

A study of electronic structures of Pt3M (M=Ti,V,Cr,Fe,Co,Ni) polycrystalline alloys with valence-band photoemission spectroscopy

The surface valence-band densities of states (DOS) of Pt(3)M (M=Ti,V,Cr,Fe,Co,Ni) polycrystalline alloys were investigated with ultraviolet photoemission spectroscopy. Upon annealing the ion-sputter-cleaned alloys at high temperatures, the observed valence-band DOS spectra clearly show the modified electronic structures on the surfaces suggesting the surface segregation of Pt as predicted in thermodynamic models. The measured d-band centers and widths for the annealed alloy surfaces show qualitatively the same trend as predicted by density-functional-theory calculations based on the model of a Pt "skin" on the topmost surface layer and a subsurface layer enriched in the 3d transition metal.     

Kopsifolines A–F: a New Structural Class of Monoterpenoid Indole Alkaloids from Kopsia

Six new indole alkaloids, named kopsifolines A–F ( 1 – 6 ), with an unprecedented hexacyclic carbon skeleton, constituting a new structural group of monoterpenoid indole alkaloids, were obtained from the leaf extract of a Malayan Kopsia species, and their structures were established by spectroscopic analysis.     

Preliminary study of fabrication technology for transmutation fuels using surrogate alloy

Journal of Radioanalytical and Nuclear Chemistry - A preliminary study on the fabrication of transmutation fuels was carried out using an injection casting technique. Melts of binary U–Zr, a...     

Surface Performance and Cytocompatibility Evaluation of Acrylic Acid-Mediated Carboxymethyl Chitosan Coating on Poly(tetrafluoroethylene-co-hexafluoropropylene)

To improve the biocompatibility of poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) film, a technique based on Ar plasma pretreatment and UV-induced grafting polymerization was used to immobilize carboxymethyl chitosan (CMCS) on the FEP film surfaces. Initially Ar plasma was used to treat FEP film. Then, plasma treated FEP film was modified via UV-induced grafting polymerization with hydrophilic acrylic acid (AAc) monomer. The following immobilization of CMCS on the FEP-pAAc surface was carried out via an amidation reaction. The change of chemical composition and surface morphology of FEP film were characterized by attenuated total reflectance Fourier transform infrared (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), scanning electronic microscopy (SEM) and atomic force microscopy (AFM). Results of water contact angles measurement showed that the hydrophilicity of the surface has improved significantly after surface modification. Furthermore, methyl thiazolyl tetrazolium (MTT) assay and cell morphology analysis confirmed that mouse fibroblasts (L929 cells) attachment and proliferation were improved remarkably on the modified FEP surface. These results suggest that CMCS were successfully employed to surface engineering FEP film, and enhanced its cell biocompatibility. The approach presented here may be exploited for surface modification of biomaterials.