Hollow fibres with walls filled with hydrogels

Although extractions using hollow fibres can be faster and more efficient than those carried out in more conventional equipment, such as mixer/separators, accidental convection through the pores in the fibre walls can compromise these advantages. A way of overcoming this drawback is to fill the walls of the fibres with a gel, such as crosslinked polyvinyl alcohol. The overall mass transfer is unaltered but the convection through the pores is eliminated.     

Out with the old in with the new

The materials issues facing the microelectromechanical systems (MEMS) community can be understood best in terms of the historical context. The field began almost as an afterthought among those engaged in integrated circuit production. These researchers recognized early on that the same processes used in the production of circuits could be re-ordered to make very small mechanical devices. The huge investment made by the electronics community in silicon technologies — and the relative ease with which these techniques could be adapted to device production — made them an obvious resource for early MEMS designers. It is no accident that polycrystalline silicon is the most commonly used structural material.But with the continued expansion of MEMS devices into new areas of application, the limitations of silicon (Si) usefulness became clear. The need to combine electronics and MEMS on the same chip (iMEMS), improve the wear characteristics of moving parts, and achieve a greater mass of moving parts in MEMS inertial sensors have led researchers away from a ‘one-material-fits-all’ approach. Instead the search is on for materials that more directly serve specific ends. The need for biocompatibility in the emerging field of bio-MEMS has added urgency to the quest for new materials, since Si-based materials cannot meet every bio-MEMS need.     

用心感知生活用感知抒写创意

前几天妹妹在我的"世界之星"颁奖仪式的照片下留言说:"哥,我没想过你的人生会这么精彩!",是啊,连我自己也从未想过我的人生能如此丰富多彩. 很多设计师是因为喜欢美术或是因为从小便培养的美术基础才选择美术专业,跟别人不同,美术是我不高的文化分数无奈之下的选择,万幸的是当我接触它时,便狂热地爱上了它.     

Writing with Fluid: Structuring Hydrogels with Micrometer Precision by AFM in Combination with Nanofluidics

Hydrogels have many applications in biomedical surface modification and tissue engineering. However, the structuring of hydrogels after their formation represents still a major challenge, in particular due to their softness. Here, a novel approach is presented that is based on the combination of atomic force microscopy (AFM) and nanofluidics, also referred to as FluidFM technology. Its applicability is demonstrated for supramolecular hydrogel films that are prepared from low‐molecular weight hydrogelators, such as derivates of 1,3,5‐benzene tricarboxamides (BTAs). BTA films can be dissolved selectively by ejecting alkaline solution through the aperture of a hollow AFM‐cantilever connected to a nanofluidic controller. The AFM‐based force control is essential in preventing mechanical destruction of the hydrogels. The resulting “chemical writing” process is studied in detail and the influence of various parameters, such as applied pressure and time, is validated. It is demonstrated that the achievable structuring precision is primarily limited by diffusion and the aperture dimensions. Recently, various additive techniques have been presented to pattern hydrogels. The here‐presented subtractive approach can not only be applied to structure hydrogels from the large class of reversibly formed gels with superior resolution but would also allow for the selective loading of the hydrogels with active substances or nanoparticles.     

Bridge circuits with pulse supply with extended functional capabilities

Bridge circuits with considerably extended functional capabilities are considered. They enable one, without any change in configuration, to determine the parameters of RL, RC, and RCL multicomponent two-terminal networks when connected to the same two leadouts of the bridge circuits. Translated from Izmeritel’naya Tekhnika, No. 4, pp. 40–45, April, 2009.     

Vehicle routing problem with vector profits with max-min criterion

This article introduces a new routing problem referred to as the vehicle routing problem with vector profits. Given a network composed of nodes (depot/sites) and arcs connecting the nodes, the problem determines routes that depart from the depot, visit sites to collect profits, and return to the depot. There are multiple stakeholders interested in the mission and each site is associated with a vector whose kth element represents the profit value for the kth stakeholder. The objective of the problem is to maximize the profit sum for the least satisfied stakeholder, i.e. the stakeholder with the smallest total profit value. An approach based on linear programming relaxation and column-generation to solve this max–min type routing problem was developed. Two case studies—the planetary surface exploration and the Rome tour cases—were presented to demonstrate the effectiveness of the proposed problem formulation and solution methodology.     

Accommodation with higher-order monochromatic aberrations corrected with adaptive optics

Higher-order monochromatic aberrations in the human eye cause a difference in the appearance of stimuli at distances nearer and farther from best focus that could serve as a signed error signal for accommodation. We explored whether higher-order monochromatic aberrations affect the accommodative response to 0.5 D step changes in vergence in experiments in which these aberrations were either present as they normally are or removed with adaptive optics. Of six subjects, one could not accommodate at all for steps in either condition. One subject clearly required higher-order aberrations to accommodate at all. The remaining four subjects could accommodate in the correct direction even when higher-order aberrations were removed. No subjects improved their accommodation when higher-order aberrations were corrected, indicating that the corresponding decrease in the depth of field of the eye did not improve the accommodative response. These results are consistent with previous findings of large individual differences in the ability to accommodate in impoverished conditions. These results suggest that at least some subjects can use monochromatic higher-order aberrations to guide accommodation. They also show that some subjects can accommodate correctly when higher-order monochromatic aberrations as well as established cues to accommodation are greatly reduced.     

Acute hemolysis with acute renal failure in a patient with valproic acid poisoning treated with charcoal hemoperfusion

Hemoperfusion consists of the passage of anticoagulated blood through a column containing adsorbent particles. It was introduced in 1940 and refined from 1950 to 1970, and then introduced clinically for the treatment of acute intoxications between 1970 and 1980. Life-threatening valproic acid toxicity is an indication for coated charcoal hemoperfusion usually accomplished without complications, but we report a case of acute severe intravascular hemolysis during the time of hemoperfusion with coated charcoal column.     

A tertiary hopf bifurcation with applications to problems with symmetries

We develop explicit criteria for the occurrence of a tertiary Hopf bifurcation, and stability of the bifurcating orbits, in a special class of two-parameter systems of ordinary differential equations. We use these results to discuss tertiary Hopf and torus bifurcations in some bifurcation problems with symmetries such as steady-state-Hopf and Hopf-Hopf interaction problems. To analyse (and even detect) these bifurcations we use invariant coordinates and rescaling techniques     

A New Control Technique with Quality Characteristic Shifting with Time

In this paper, a new quality control technique is discussed, in which the quality characteristic shifts with time. A trends semi‐circle control chart is proposed to control this type of processes effectively. An optimization model is suggested to determine the optimal interval of adjustment. We also discuss the average run length of the proposed control chart and the extension to the EWMA chart. An example is used to illustrate its application in a production process. Copyright © 2015 John Wiley & Sons, Ltd.     

Computer-generated holograms with optimum bandwidths obtained with twisted-nematic liquid-crystal displays

We discuss a computer-generated hologram for encoding arbitrary complex modulation based on a commercial twisted-nematic liquid-crystal display. This hologram is implemented with the constrained complex modulation provided by the display in a phase-mostly configuration. The hologram structure and transmittance are determined to obtain on-axis signal reconstruction, maximum bandwidth, optimum efficiency, and high signal-to-noise ratio. We employed the proposed holographic code for the experimental synthesis of first-order Bessel beams.     

置换通风与冷却顶板的热舒适性研究

置换通风与冷却顶板结合是一种新型的空调方式。本论述了在置换通风与冷却顶板结合的空调系统中,各种参数对人体热舒适性的影响,提出基于人体热舒适性要求最合适的设计值。另外,还分析了ＩＳＯ７７３０标准所依据的热舒适性模型在置换通风与冷却顶板系统中的适用性。     

Calculation and design of sheets with a circular hole with equal strength reinforcement and with minimum mass

Translated from Fiziko-Khimicheskaya Mekhanika Materialov, No. 4, pp. 92–96, July–August, 1988.     

Enhanced gene transfer with multilayered polyplexes assembled with layer-by-layer technique

Successful gene therapy asks for multifunctional vectors which can not only protect DNA from degradation but also transfer it into nuclear and subsequently express the loaded gene. Here we reported a novel multilayered delivery system constructed with DNA, protamine (Pro) and polyethylenimine (PEI) via lay-by-layer (LbL) technique, which posed multifunctions. DNA was previously condensed into a compact core with Pro which also contained nuclear localisation signals (NLS) domains for nuclear transfer. Then additional DNA was deposited as the first layer onto the cationic core via the electrostatic attraction which would increase the loading dose of DNA. At last, PEI was absorbed as the outmost layer to achieve the endosomal escape. Therefore a quaternary polyplexes which offered high loading of DNA, nuclear transfer ability and endosomal escape capability was constructed with the LbL technique. The obtained quaternary polyplexes showed positive surface charge, spherical morphology, a relatively narrow particle size distribution and strong DNA protection capability. Compared with commercially available PEI/DNA complexes, the novel multifuctional vector exhibited not only lower cytotoxicity (P<0.05) but also higher transfection efficiency in HepG2 and HeLa cells (P<0.05) in vitro test.     

基于Kirov定理的带可控参数的多结点造型方法

基于Kirov定理,利用多结点样条函数,研究一类带有可控参数的曲线曲面造型方法。该方法是在普通的多结点样条中加入可控参数,通过调节这些参数可以控制插值曲线(面)在各型值点的切向量(切平面或法向量),从而达到满意的曲线(面)造型效果。该方法保持了多结点样条的基数型和局部性特点,特别是局部性使得可以只对插值曲线(面)作局部调整而不会影响整体,这有助于CAD或CAGD领域的工程人员去设计、调整曲线(面)的形状。     

Refrigeration with ammonia

Ammonia is widely used as a refrigerant in industrial systems for food refrigeration, distribution warehousing and process cooling. It has more recently been proposed for use in applications such as water chilling for air-conditioning systems but has not yet received widespread acceptance in this field. This review paper assesses the reasons why ammonia is so popular in industrial systems, the reasons why it is deemed less suitable for other applications and the possible benefits at local, national and international levels that might be gained by more general acceptance of ammonia as a refrigerant. The paper also considers other possible applications which might benefit from the use of ammonia as refrigerant.