蒸馏沉淀聚合过程中交联度对单分散聚合物微球形成的影响

以苯乙烯为单体、二乙烯基苯(DVB)为交联剂,过氧化二苯甲酰(BPO)为引发剂研究了蒸馏沉淀聚合法制备聚合物微球过程中交联单体二乙烯苯的用量对单分散聚合物微球成球的影响.结果表明,增加二乙烯基苯的比例,即提高交联度有利于形成单分散的聚合物微球.     

Highly sensitive electrochemical detection of trace liquid peroxide explosives at a Prussian-blue 'artificial-peroxidase' modified electrode

A highly sensitive electrochemical assay of the peroxide-based explosives triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD) at a Prussian-blue (PB) modified electrode is reported. The method involves photochemical degradation of the peroxide explosives and a low potential (0.0 V) electrocatalytic amperometric sensing of the generated hydrogen peroxide at the PB transducer and offers nanomolar detection limits following a short (15 s) irradiation times. The electrochemical sensing protocol should facilitate rapid field screening of peroxide explosives.     

Application of perceptual difference model on regularization techniques of parallel MR imaging

Parallel magnetic resonance imaging through sensitivity encoding using multiple receiver coils has emerged as an effective tool to reduce imaging time or to improve image SNR. The quality of reconstructed images is limited by the inaccurate estimation of the sensitivity map, noise in the acquired k-space data and the ill-conditioned nature of the coefficient matrix. Tikhonov regularization is a popular method to reduce or eliminate the ill-conditioned nature of the problem. In this approach, selection of the regularization map and the regularization parameter is very important. Perceptual difference model (PDM) is a quantitative image quality evaluation tool that has been successfully applied to varieties of MR applications. High correlation between the human rating and PDM score shows that PDM should be suitable to evaluate image quality in parallel MR imaging. By applying PDM, we compared four methods of selecting the regularization map and four methods of selecting the regularization parameter. We found that a regularization map obtained using generalized series (GS) together with a spatially adaptive regularization parameter gave the best reconstructions. PDM was also used as an objective function for optimizing two important parameters in the spatially adaptive method. We conclude that PDM enables one to do comprehensive experiments and that it is an effective tool for designing and optimizing reconstruction methods in parallel MR imaging.     

Synthesis of core-shell polymer microspheres by two-stage distillation-precipitation polymerization

Narrow- or monodisperse core-shell polymer microspheres with a dense core and a lightly crosslinked shell with different functional groups, such as ester, hydroxyl, cyano, were prepared by two-stage distillation-precipitation polymerization without any stabilizer. Commercial divinylbenzene (DVB), containing 80% of DVB was polymerized by distillation-precipitation polymerization with 2,2′-azobis(2-methyl propionitrile) (AIBN) as initiator in neat acetonitrile in the absence of any stabilizer as the first stage polymerization and used as the core. When the conversion of DVB was about 35% in the first stage, the second-comonomers with different functional groups, such as methyl methacrylate (MMA), ethyl methacrylate (EMA), butyl methacrylate (BMA), 2-hydroxyethyl methacrylate (HEMA), i-octyl acrylate (i-OA), dodecyl acrylate (DA), methyl acrylate (MA), ethyl acrylate (EA), ethylene glycol dimethacrylate (EGDMA), triethyleneglycol dimethacrylate (TEGDMA), trimethylolpropane trimethacrylate (Trim), and acrylnitrile (AN) together with AIBN were introduced, respectively, into the reaction system and copolymerized with unreacted DVB on the core surface to form a lightly crosslinked functional shell. The resulting core-shell polymer particles were characterized with scanning electron microscopy (SEM) and FT-IR spectra.     

富勒烯C70及Sc3N@C70的密度泛函理论研究

在混合密度泛函B3LYP理论下,用6-31G*基函数对富勒烯C70、它的阴离子及内掺Sc3N富勒烯Sc3N@C70两种同分异构体的几何结构和电子结构进行了研究。计算结果表明,在C70的两种异构体中,满足五元环分离规则(IPR)的C70(D5h)稳定,C70q-(#7854)(q=4,6)比C70q-(D5h)稳定;在Sc3N@C70两种异构体中有三对两两相邻五元环的Sc3N@C70(#7854)稳定,C70(#7854)易于形成富勒烯金属包合物。     

术前经动脉化疗栓塞治疗婴儿肾母细胞瘤的疗效观察

目的探讨术前经动脉化疗栓塞治疗婴儿肾母细胞瘤的可行性。方法2009年6月至2014年5月收治6例婴儿单侧肾母细胞瘤,术前评估肿瘤手术一期切除困难,所有婴儿均行经导管肾动脉化疗栓塞,术后4周内行肿瘤根治性手术切除,记录并分析6例婴儿的治疗结果、并发症及随访结果。结果6例婴儿介入后肿瘤体积均缩小,平均缩小39.03%（23.95%~61.8%）,介入治疗总有效率达83.33%（5/6）;手术中瘤体完整切除率为100%,无肿瘤破溃及污染腹腔情况。手术后随访时间平均为42.8个月,无肿瘤复发、远处转移及死亡。结论术前经动脉化疗栓塞治疗婴儿巨大肾母细胞瘤是安全、有效的,能为一期手术切除困难的肾母细胞瘤患儿提供一种新的治疗模式。     

Methods for quantitative image quality evaluation of MRI parallel reconstructions: detection and perceptual difference model

Many reconstruction algorithms are being proposed for parallel magnetic resonance imaging (MRI), which uses multiple coils and subsampled k-space data, and a quantitative method for comparison of algorithms is sorely needed. On such images, we compared three methods for quantitative image quality evaluation: human detection, computer detection model and a computer perceptual difference model (PDM). One-quarter sampling and three different reconstruction methods were investigated: a regularization method developed by Ying et al., a simplified regularization method and an iterative method proposed by Pruessmann et al. Images obtained from a full complement of k-space data were also included as reference images. Detection studies were performed using a simulated dark tumor added on MR images of fresh bovine liver. Human detection depended strongly on reconstruction methods used, with the two regularization methods achieving better performance than the iterative method. Images were also evaluated using detection by a channelized Hotelling observer model and by PDM scores. Both predicted the same trends as observed from human detection. We are encouraged that PDM gives trends similar to that for human detection studies. Its ease of use and applicability to a variety of MRI situations make it attractive for evaluating image quality in a variety of MR studies.     

Theoretical study on C100 fullerenes and C96X4 (X=N,P, B,Si)

The geometrical structures and electronic properties of six fullerene isomers of C₁₀₀ were studied at the HF/6-31G^? and B3LYP/6-31G^? levels, respectively. The results of the fully optimized calculations show that three C₁₀₀ isomers 449:D₂, 425:C₁ and 442:C₂ are near isoenergetic isomers. The energies and properties of C₁₀₀ hexaanions were calculated. The C₁₀₀^6? (450:D₅) isomer is predicted to be the most stable isomer at the B3LYP/6-31G^? level, and the C₁₀₀^6? (449:D₂) isomer is 44.1 kcal/mol higher in energy. The heterofullerenes C₉₆X₄ (X=N, P, B, Si) formed from the initial C₁₀₀ (449:D₂) have also been investigated at the B3LYP/6-31G^? level. The HOMO–LUMO gaps and aromaticities show that the replacement of fullerene carbon atoms with four heteroatoms can enhance the electronic stabilization of C₁₀₀ (449:D₂).     

Photosensitive Azopolymer Brushes via Atom Transfer Radical Polymerization for Protein Sensing

Novel photosensitive azopolymer brushes were synthesized via surface initiated atom transfer radical polymerization using initiator self‐assembled on Au surface. The chemical structures of azobenzene derivatives were confirmed by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR). The surface morphology of azopolymers via atom transfer radical polymerization (ATRP) for different time was investigated by atomic force microscopy (AFM). Additionally, the photoisomerization of azopolymer was measured by ultraviolet‐visible spectroscopy (UV‐Vis). The results indicate that such azopolymers can undergo trans‐cis‐trans photoisomerization efficiently by photo‐irradiation with UV light. Furthermore, this photoisomerization property could also induce the reversible adsorption of bovine serum albumin (BSA) adsorption on azopolymer brush surfaces. This adsorption kinetics of the reversible process can be measured by surface plasmon resonance (SPR) spectroscopy in situ. It suggests that the protein biochips could be regenerated safely by UV irradiation rather than by being rinsed with chemical reagents.