一种基于增强现实的室内漫游系统

提出了一种基于增强现实的室内漫游系统,在这个系统中用户通过HMD观察增强的视景。在这个视景中不但包含真实布景的图像,还包含有计算机生成的虚拟物体的图像。为了实现虚实场景之间的注册,在HMD上安装有两个摄像机:场景摄像机与跟踪摄像机。并且在用户所在房间的顶部安装了一系列的红外标志点,这些标志点的图像由跟踪摄像机获取,并通过位置估计算法计算用户头部的位置和姿态。另外,通过一对安装有ARtoolKit标志点的手套,实现用户与虚拟环境之间的交互。最后,一套海底漫系统被开发出来,以验证整个漫游系统的可用性     

用于原子吸收光谱仪的高灵敏度燃烧器

本文介绍了一种用于原子吸收光谱仪的气－样分进、双通道燃烧器，经过实际检测比较，该坷提高原子吸收灵敏度１￣５倍，且稳定性好。     

HS-6顶空进样器的性能考察及其应用

考察了连接在Sigmal气相色谱仪上的HS-6顶空分析器的性能,特别注意考察了样品的体积,平衡所需时间和分流比等对保留时间和峰高的影响,研究结果还表明增加样品的加热温度和稀释样品的浓度会改善测定的灵敏度,文章还给出了一系列不同类型样品的应用结果,包括香烟、茶叶、啤酒、中药等。     

Minimization of erase-band in shingled PMR with asymmetric writer

To make the write-field much stronger with sharper cross-track field gradient in Shingled perpendicular Magnetic Recording (SMR), we have successfully developed asymmetric SMR heads with one-side shield design. Using these heads, higher track density capability on the shielded-side was demonstrated, which came from narrower erase-band width at shielded side.     

Novel Azobenzene-Functionalized Polyelectrolytes of Different Substituted Head Groups 2: Control of Surface Wetting in Self-Assembled Multilayer Films

A novel set of light-responsive polyelectrolytes has been developed and studied, to control and tune surface wettability by introducing various types of substituted R head-groups of azo polyelectrolytes in self-assembled multilayer (SAMU) films. As part of a larger project to develop polymer surfaces where one can exert precise control over properties important to proteins and cells in contact, photo-reversibly, we describe here how one can tune quite reliably the contact angle of a biocompatible SAMU, containing a photo-reversible azo chromophore for eventual directed cell growth. The azo polyelectrolytes described here have different substituted R head-group pairs of shorter-ionized hydrophilic COOH and SO₃H, shorter non-ionized hydrophobic H and OC₂H₅, and larger non-ionized hydrophobic octyl C₈H₁₇ and C₈F₁₇, and were employed as polyanions to fabricate the SAMU onto silicon substrates by using the counter-charge polycation PDAC. The prepared SAMU films were primarily characterized by measurement of their contact angles with water. The surface wetting properties of the thin films were found to be dependent on the type of substituted R-groups of the azo polyelectrolytes through their degree of ionization, size, hydrophobicity/hydrophilicity, solubility, conformation, and inter-polymeric association and intra-polymeric aggregation. All these factors appeared to be inter-related, and influenced variations in hydrophobic/hydrophilic character to different extents of aggregates/non-aggregates in solution because of solvation effects of the azo polyanions, and were thus manifested when adsorbed as thin films via the SAMU deposition process. For example, one interesting observation is significantly higher contact angles of 79° for SAMU films of larger octyl R groups of PAPEA-C₈F₁₇ and PAPEA-C₈H₁₇ than for others with contact angles of 64° observed for non-polar R-groups of OC₂H₅ and H. Furthermore, lower contact angle values of 59° for SAMU films with polar R-groups of COOH and SO₃H relative to that of non-polar R-groups are in accordance with their expected order of the hydrophilicity or hydrophobicity. It is possible that the large octyl groups are more effective in shielding the ionic functional groups on the substrate surface, and contributed less to the water drop-molecule interactions with ionic groups of the PDAC and/or AA groups. In addition, higher hydrophobicity of the SAMU films may be due to the incorporation of bulky and hydrophobic groups in these polyelectrolytes, which can produce aggregates on the surfaces of the SAMU films. Through understanding and controlling the complex aggregation behavior of the different substituted R-groups of these azo polyelectrolytes, and hence their adsorption on substrates, it appears possible to finely tune the surface energy of these biocompatible films over a wide range, enhance the photo-switching capabilities of the SAMU films, and tailor other surface properties for the development and application of new devices in diverse areas of microfluidics, specialty coatings, sensors, and biomedical sciences.     

The Use of Various Chromatographic Techniques for the Determination of Phenylurea Herbicides and Their Corresponding Anilines in Environmental Samples,II. Applications

Abstract

In earlier work, various strategies have been developed for the trace-level determination of phenylurea herbicides and the anilines which are their main degradation products. They include catalytic hydrolysis of the phenylureas on silica, liquid chromatographic fractionation of complex mixtures of herbicides and anilines, derivatization of anilines and herbicides with electron-capture-sensitive reagents, and final analysis by means of capillary gas chromatography. In the present paper, the application of these principles to trace-level analysis of surface water, soil and crop samples is demonstrated.     

Highly Selective Dimerization and Trimerization of Isobutene to Linearly Linked Products by Using Nickel Catalysts

The unique linear linkage of isobutene to generate highly valuable C₈ precursors for plasticizers is feasible by using special nickel catalysts. (4‐Cyclooctene‐1‐yl)(1,1,1,5,5,5‐hexafluoro‐2,4‐acetylacetonato)nickel and aluminum‐alkyl‐activated nickel acetylacetonates produce isobutene dimers with high selectivities of up to 95 %. Moreover, selectivity for the head‐to‐head products (2,5‐dimethylhexenes) is remarkably high at up to 99 %. Additionally, novel C₁₂ isobutene trimers are also formed with a very high selectivity of up to 99 % for the linear linkage. The trimer structure (2,5,8‐trimethylnonenes) reflects the stepwise characteristic of the reaction mechanism. Pathways of insertion and activation and the deactivation processes of the catalyst are discussed in detail.     

Effect of Botanical Extracts on the Growth and Nutritional Quality of Field-Grown White Head Cabbage (Brassica oleracea var. capitata)

Nutraceuticals and functional foods are gaining more attention amongst consumers interested in nutritious food. The consumption of foodstuffs with a high content of phytochemicals has been proven to provide various health benefits. The application of biostimulants is a potential strategy to fortify cultivated plants with beneficial bioactive compounds. Nevertheless, it has not yet been established whether the proposed higher plants (St. John’s wort, giant goldenrod, common dandelion, red clover, nettle, and valerian) are appropriate for the production of potential bio-products enhancing the nutritional value of white cabbage. Therefore, this research examines the impact of botanical extracts on the growth and nutritional quality of cabbage grown under field conditions. Two extraction methods were used for the production of water-based bio-products, namely: ultrasound-assisted extraction and mechanical homogenisation. Bio-products were applied as foliar sprays to evaluate their impact on total yield, dry weight, photosynthetic pigments, polyphenols, antioxidant activity, vitamin C, nitrates, micro- and macroelements, volatile compounds, fatty acids, sterols, and sugars. Botanical extracts showed different effects on the examined parameters. The best results in terms of physiological and biochemical properties of cabbage were obtained for extracts from common dandelion, valerian, nettle, and giant goldenrod. When enriched with nutrients, vegetables can constitute a valuable component of functional food.     

4T split TEM volume head and knee coils for improved sensitivity and patient accessibility

Split RF coils offer improved patient access by eliminating the need for the coil to be slid over the region of interest. For unshielded birdcage coils, the presence of end ring currents necessitates a direct electrical connection between two halves of the coil. For high-field (>3T) shielded birdcage coils, both the shield and the coil must be split and reliably connected electrically. This problem can be circumvented by the use of split TEM volume coils. Since the elements of a TEM coil are coupled inductively, no direct electrical connection between the halves is necessary. In this work we demonstrate that the effects of splitting the shield for head and knee TEMs can be compensated for, and performance retained. For the knee, the improved access allowed the coil diameter to be reduced, enhancing the sensitivity by 15-20%.     

小孔流速实验中的排水时间和流量系数的研究

本文以水作为理想流体,考虑到水头损失和孔口缩流效应,对小孔流速实验涉及的容器排水问题进行了系统的理论和实验研究.从理论上推导得出了圆柱形容器排水时间的解析解,分析了排水时间和自由液面速度、流量系数之间的规律,提出了排水时间的等效性.实验上,加工了底部开有不同小孔的大型圆柱形容器,测量了容器排水时间随液面高度的变化关系,借助实验结果计算了流量系数值,验证了容器排水时间的等效性关系,实验结果与理论计算符合较好.