A rotating phantom for the study of flow effects in MR imaging

A common type of phantom used for the study of flow effects in MR imaging is the tube phantom, where a liquid passes through a set of tubes placed in the main magnetic field of an MR scanner. Among the disadvantages with this type of phantom are that a distribution of velocities is present in each tube, and that quantifications of flow effects using tube phantoms may be very time-consuming. In this work, we describe the design and the properties of a rotating wheel flow phantom used for quantification of the effects of flow through the imaging plane as well as in the imaging plane. The proposed phantom is constructed as a rotating gel-filled wheel, surrounded by static volumes filled with the same gel, and the evaluation of the information from rotating and static parts is made with a specially designed computer program. The phantom can be used as a plug flow phantom covering simultaneously an interchangeable velocity interval, which at present has the range −52 mm/s, +52 mm/s. It is shown that the phantom gives adequate information on the dependence of pixel content on first-order motion in MR modulus and phase images. Among the fields of application are rapid calibration of MR imaging units for flow determination using phase information, as well as testing of pulse sequence characteristics and verification of theoretical predictions concerning the flow dependence in MR images.     

Integrating Al with NiO nano honeycomb to realize an energetic material on silicon substrate

Nano energetic materials offer improved performance in energy release, ignition, and mechanical properties compared to their bulk or micro counterparts. In this study, the authors propose an approach to synthesize an Al/NiO based nano energetic material which is fully compatible with a microsystem. A two-dimensional NiO nano honeycomb is first realized by thermal oxidation of a Ni thin film deposited onto a silicon substrate by thermal evaporation. Then the NiO nano honeycomb is integrated with an Al that is deposited by thermal evaporation to realize an Al/NiO based nano energetic material. This approach has several advantages over previous investigations, such as lower ignition temperature, enhanced interfacial contact area, reduced impurities and Al oxidation, tailored dimensions, and easier integration into a microsystem to realize functional devices. The synthesized Al/NiO based nano energetic material is characterized by scanning electron microscopy, X-ray diffraction, differential thermal analysis, and differential scanning calorimetry.     

Prediction of lower flammability limits of blended gases based on quantitative structure–property relationship

Journal of Thermal Analysis and Calorimetry - The main goal of this research was to improve a carbonate-type foaming agent for the production of Al foams. Various systematic treatments, i.e....     

Green Synthesis of Red‐Emitting Carbon Nanodots as a Novel “Turn‐on” Nanothermometer in Living Cells

Temperature measurements in biology and medical diagnostics, along with sensitive temperature probing of living cells, is of great importance; however, it still faces significant challenges. Herein, a novel “turn‐on” carbon‐dot‐based fluorescent nanothermometry device for spatially resolved temperature measurements in living cells is presented. The carbon nanodots (CNDs) are prepared by a green microwave‐assisted method and exhibit red fluorescence (λ_em=615 nm) with high quantum yields (15 %). Then, an on–off fluorescent probe is prepared for detecting glutathione (GSH) based on aggregation‐induced fluorescence quenching. Interestingly, the quenched fluorescence could be recovered by increasing temperature and the CNDs–GSH mixture could behave as an off–on fluorescent probe for temperature. Thus, red‐emitting CNDs can be utilized for “turn‐on” fluorescent nanothermometry through the fluorescence quenching and recovery processes, respectively. We employ MC3T3‐E1 cells as an example model to demonstrate the red‐emitting CNDs can function as “non‐contact” tools for the accurate measurement of temperature and its gradient inside a living cell.     

Synthesis and evaluation of novel ascorbyl cinnamates as potential anti-oxidant and antimicrobial agents

Research on Chemical Intermediates - An efficient preparation procedure has been proposed for the synthesis of 5,6-di-O-cinnamyl-l-ascorbic acid ester (5,6-CA–AA) and 2-O-cinnamyl-l-ascorbic...     

Selection of cholesterol esterase aptamers using a dual‐partitioning approach

Non‐systematic evolution of ligands by exponential enrichment and other capillary‐based methods have grown in popularity for selection of aptamers since they provide a fast and efficient partitioning method when compared to classical techniques. Despite promising developments in these techniques, a major obstacle needs to be overcome for capillary‐based selections to be widely accepted. Due to the small injection volumes associated with CE, only a small proportion of the nucleic acid library can be partitioned at any one time. In this paper, we propose a new two‐step method for the selection of aptamers which firstly incorporates a nitrocellulose membrane filter followed by CE. This technique allows for nonbinding sequences to be eliminated, reducing the library size before subsequent capillary‐based partitioning, while still reducing the time taken for aptamers to be selected. We demonstrated this technique on the selection of aptamers for cholesterol esterase and the highest binding truncated aptamer CES 4T displayed a K_D of 203 ± 14 nM. In addition, an increase in the number of sequences partitioned was estimated using spectrophotometry and capillary injection volumes. The results suggested that for successful selection a two‐step approach is needed. This hybrid technique could be used to select aptamers that bind to targets both in solution and immobilized onto a stationary phase, allowing the aptamers to be used in different binding environments.     

表面Mo修饰提高CeTiO_x催化剂低温脱硝性能（英文）

近年来,以雾霾为代表的大气污染问题严重影响到经济社会的可持续发展.其中,氮氧化物(NOx)的大量排放是导致雾霾天气的重要原因之一.氨选择性催化还原(NH3-SCR)是目前消除氮氧化物的主流技术,低温NH3-SCR更是广泛应用于钢铁、焦化、水泥、玻璃、陶瓷和垃圾焚烧等行业的烟气排放治理.传统的V2O5-WO3/Ti O2催化剂活性温度高(300–400 oC)且钒具有生物毒性,因此亟待开发环境友好的低温非钒基脱硝催化剂.最近, Ce Ti Ox基催化剂由于在中高温段(250–400 oC)表现出优异的脱硝性能而得到广泛关注.然而,该催化剂仍面临低温活性差及抗硫性能差的问题,制约了其工业化应用.研究显示,添加过渡金属可提高Ce Ti Ox基催化剂的脱硝活性和抗硫中毒性能,这主要是因为过渡金属的添加可以有效改善催化剂的氧化还原性能和表面酸性.Mo O3作为一种可以提供大量酸性位的氧化物,常被用作助剂改善钒钨钛催化剂的活性.研究显示, Mo O3的引入可以促进催化剂中钒物种的分散度以及提高表面酸性.基于此,我们制备了一系列不同Mo含量的Mo O3/Ce Ti Ox催化剂,以期提高Ce Ti Ox催化剂的低温脱硝性能及抗SO2中毒能力,并着重研究表面Mo的修饰对Ce Ti Ox催化剂物理化学性质的影响.研究发现,表面Mo修饰可以显著提高Ce Ti Ox的低温催化活性,其脱硝效率在150 oC即可达到80%,同时抗SO2中毒能力也得到增强.进一步借助X射线衍射、比表面积测定、氢气程序升温还原、氨气程序升温脱附和X射线光电子能谱等方法对催化剂进行了全面表征分析.结果显示,表面Mo修饰对Ce Ti Ox催化剂物理化学性质的影响与其脱硝性能有着密不可分的关系.首先,钼物种主要是以Mo O3的形式存在于Ce Ti Ox表面,其最佳的负载量为4wt.%.其次,表面Mo的沉积显著提高了催化剂的表面酸量,尤其是Br?nsted酸位的数量,而表面酸位的增加有利于催化剂吸附与活化反应物种NH3;同时,表面Mo修饰还减弱了硝酸盐在催化剂表面的吸附,进一步促使NH3-SCR反应按照Eley-Rideal机理顺利进行.最后,该催化剂在H2O和SO2存在的条件下仍具有最佳的脱硝性能,因而有望用于实际含SO2的低温烟气脱硝.     

具有阶段结构和时滞的捕食系统

§ 1　IntroductionThe competitive,cooperative and predator-prey models have been studied by many au-thors.[1— 4] The permanence (or strong persistence) and extinction are significant conceptsof those models.However,the stage structure of species has been considered very little.Inthe real world,almost all animals have the stage structure of immature and mature.Re-cently,papers[5— 7] studied the stage structure of species,the transformation rate of ma-ture population is proportional to the ex…     

Laterally-corrugated ridge-waveguide distributed feedback lasers at 980 nm

The paper presents a simulation-based analysis of laterally-corrugated ridge-waveguide distributed feedback semiconductor lasers emitting at 980 nm. The simulations were performed using software developed in-house and the PICS3D software package from Crosslight Software Inc. The effects of the corrugation geometry, phase-shift section, and mirror reflectivities on single longitudinal mode operation are discussed. The lasers, designed along the guidelines derived from the simulation results, were fabricated by using molecular beam epitaxy for wafer growth and low-cost nano-imprint lithography. They exhibited stable single-mode operation with up to 50 dB side-mode suppression ratio.     

养殖鱼邻苯二甲酸酯的含量分析

目的：为了解宁波地区淡水养殖鱼PAEs污染情况。方法采用液液超声萃取-气质联用法对宁波6个不同养殖点5种淡水养殖鱼体内8种邻苯二甲酸酯含量进行分析。结果宁波地区养殖鱼主要受 DMP、 DEP、 DBP、 DEHP 和 DOP 污染，质量分数最高可达134.1、258.9、249.2、830.8和5029μg/kg；草鱼、鳊鱼、鳙鱼、鲫鱼和乌鳢邻苯二甲酸污染指数PPI分别为9.999、9.735、13.97、8.945和5.809μg/kg。结论宁波地区淡水养殖鱼鱼体邻苯二甲酸酯含量与养殖环境有关，与鱼种无关。