On-Demand DNA Synthesis on Solid Surface by Four Directional Ejectors on a Chip

This paper presents a synthesis technique for any random deoxyribonucleic acid (DNA) sequences on different substrates such as glass, plastic or silicon by an array of directional droplet ejectors. Any DNA sequence can be synthesized by ejecting droplets of DNA bases by an ultrasonic transducer having lens with air-reflectors (LWARs) that requires no nozzle. The LWAR is capable of ejecting liquid droplets around 80 mum in diameter, and reduces the amount of reagents needed for the synthesis from most of conventional microarray techniques. One major advantage of the nozzleless ejector is that it can eject droplets in any direction, so that a spot can be inked by four ejectors (carrying four DNA bases) without moving the ejector. The directional ejection of the droplets removes the need for aligning the substrate with the ejector, and minimizes the automation and control circuitry. To demonstrate the DNA synthesis capability of the directional droplet ejectors, four LWAR ejectors were used to synthesize a 15-mer 5'-CGCCAAGCAGTTCGT-3' on a substrate surface. This paper describes the concept and scheme of the on-demand DNA synthesis (with MEMS ejector integrated with microfluidic components) along with experimental results of an actual DNA synthesis by four directional droplet ejectors.     

A survey and comparison of multichannel protocols for performance anomaly mitigation in IEEE 802.11wireless networks

Providing multichannel functionality can improve the performance of wireless networks. Although off‐the‐shelf IEEE 802.11 physical layer and medium access control specifications support multiple channels and multiple data rates, one of the major challenges is how to efficiently utilize available channels and data rates to improve network performance. In multirate networks, low‐rate links severely degrade the capacity of high‐rate links, which is known as performance anomaly. To overcome the performance anomaly problem, different data rate links can get equal air‐time by exploiting time diversity and frequency diversity, or they can be separated over nonoverlapping channels. In this paper, we study existing multichannel protocols proposed to mitigate the performance anomaly problem by classifying them into single‐radio protocols, multiradio single‐hop protocols, and multiradio multihop protocols. To investigate the effectiveness of multichannel solutions for performance anomaly, we compare these protocols with well‐known multichannel protocols that do not consider performance anomaly. In addition, this paper gives insightful research issues to design multichannel protocols that mitigate performance anomaly in IEEE 802.11 wireless networks. Copyright © 2012 John Wiley & Sons, Ltd.     

Exact truss topology optimization for external loads and friction forces

In replying to a valuable Discussion by Mariano Vázquez Espi, the authors show that the problem of friction forces in general can be handled by the Prager-Rozvany layout theory, and the optimal Michell layout does not always correspond to the maximum value of the static friction force. Moreover, it is explained that discontinuities in the specific cost function can be accommodated by an extended version of the Prager-Shield optimality criteria, which was already demonstrated in the second author’s first (1976) book.     

Enzymatic reduction of polyunsaturated lysophosphati‐dylcholine hydroperoxides by glutathione peroxidase‐1

Some lipid peroxides are known to be converted to their corresponding alcohols in cells containing glutathione peroxidase (GPx). In this respect, we examined the enzymatic conversion of lysophosphatidylcholine (lysoPC) hydroperoxides to hydroxyl derivatives using RBL‐2H3 cells and erythrocyte GPx‐1. First, the incubation of RBL‐2H3 cells with arachidonoyl lysoPC led to the formation of a major product, with maximal UV absorbance at 234 nm and m/z [M+H]⁺ at 560.2, corresponding to monohydroxyeicosatetraenoyl lysoPC. Similarly, linoleoyl lysoPC was also converted to its hydroxyl derivative in RBL‐2H3 cells. Separately, lysoPC hydroperoxide, generated from soybean lipoxygenase 1‐catalyzed oxygenation of linoleoyl lysoPC, arachidonoyl lysoPC or docosahexaenoyl lysoPC, was converted by GPx‐1 to the corresponding hydroxyl derivatives. When the kinetic values were determined, the K_m values (3.1–32.3 µM) of the polyunsaturated lysoPC hydroperoxides increased with decreasing number of double bonds, in contrast to a similar value of V_m among them. Moreover, the catalytic efficiency of docosahexaenoyl lysoPC hydroperoxide was much greater than that of H₂O₂ as substrate of GPx‐1. In related experiments, where phosphatidylcholine hydroperoxides were incubated with phospholipase A₂ and GPx‐1, the complete conversion of phosphatidylcholine hydroperoxides to hydroxyl derivatives was confirmed by LC/MS. Taken together, it is proposed that GPx‐1‐type enzymes may participate in the conversion of polyunsaturated lysoPC hydroperoxides to hydroxyl derivatives in cell systems.     

On the solution of the three forces problem and its application in optimal designing of a class of symmetric plane frameworks of least weight

Two problems of minimum weight design of plane trusses are dealt with. The first problem concerns construction of the lightest fully stressed truss subject to three self-equilibrated forces applied at three given points. This problem has been solved analytically by H.S.Y. Chan in 1966. This analytical solution is re-derived in the present paper. It compares favourably with new numerical solutions found here by the method developed recently by the first author. The solution to the three forces problem paves the way to half-analytical as well as numerical solutions to the problem of minimum weight design of plane symmetric frameworks transmitting two symmetrically located vertical forces to two fixed supports lying along the line linking the points of application of the forces.     

Inhibition of lysophospholipase D activity by fish egg extracts

Lysophospholipase D (lysoPLD) is known to convert lysophosphatidylcholine (LPC) to lysophosphatidic acid (LPA). In this study, we examined the inhibitory effect of fish egg extracts, containing lipids, on bovine lysoPLD activity. Fish eggs extracts were tested for the inhibition of lysoPLD activity, and the inhibitory action was expressed as 50% inhibitory concentration (IC₅₀). Among fish egg extracts of 20 fish species, the most potent inhibition was expressed by Hairtail egg extract (IC₅₀, 0.07 ± 0.01 mg egg weight/mL), followed by extract of Spanish mackerel egg extract (0.11 ± 0.02 mg egg weight/mL) and extract of Pacific saury egg (0.48 ± 0.03 mg egg weight/mL). In ESI/MS analysis, major lysoPLD-inhibitory lipid components in egg extracts were identified to be species of LPC, LPA and fatty acid. From these results, it is suggested that the strong inhibition of lysoPLD activity by fish egg extracts might be ascribed to the presence of lysophospholipids. In a separate study, enzymatic oxidation using lipoxygenase or non-enzymatic oxidations such as HOCl oxidation or Cu²⁺-catalyzed oxidation enhanced the inhibitory activity to some extent, suggesting that the oxidation of polyunsaturated lysophospholipids might contribute to the increase of lysoPLD-inhibitory action. Taken together, it is suggested that fish eggs may contain potent lipid inhibitors of lysoPLD, and that the inhibitory action of lipid inhibitors was enhanced by oxidative process.     

加拿大重瓦斯油催化裂化研究--不同反应器的产品产率与质量对比

Several series of cracking tests in a comprehensive study were conducted on separate occasions involving all or parts of ten Canadian vacuum gas oils (VGOs) and two catalysts with bottoms-cracking or octane-barrel capability.VGOs were cracked in fixed- and/or fluid-bed microactivity test (MAT) units, in an Advanced Cracking Evaluation (ACE)unit, and in a modified ARCO riser reactor. Individual yields of gas, liquid, and coke from the MATs at 55, 65, 70, and 81 wt% conversion levels were compared with their respective pilot plant data. Good linear correlations could be established between MAT and riser yields except for liquefied petroleum gas (LPG) and light cycle oil (LCO). At a given conversion,correlations existed among the fixed- and fluid-bed MAT units and the ACE for each product yield. Liquid products from the fixed or fluid-bed MAT were analyzed for hydrocarbon types, sulfur, nitrogen and density, most of which showed good agreement with those obtained from the riser study. When cracking Canadian oil-sands-derived VGOs, the bottomscracking catalyst containing a large-pore active matrix was found to be more suitable than the octane-barrel catalyst with smaller pores to produce higher yields of valuable distillates, but with less superior qualities (in terms of sulfur and nitrogen contents). The advantages of hydrotreating some poor feeds to improve product yields and qualities were demonstrated and discussed.     

Discolouration of raw and cooked coloured fleshed potatoes differing in anthocyanins and polyphenols content

Despite variations in the content of polyphenols, the tested potato varieties with red and purple flesh contained similar amounts of anthocyanins. Potatoes of the red-fleshed HBr variety were distinguished by a significant content of pelargonidin-3-feruloylrutinoside-5-glucoside, and those of the purple-fleshed Vitelotte variety were characterised by a significant cyanidin-3-rutinoside content. Immediately after cutting, raw potatoes with red flesh showed a small share of yellow (b* parameter) and double the share of red (a*) as compared to purple-fleshed tubers. A reduction in the share of red dye was observed in purple- and red-fleshed potatoes except Vitelotte and Rosalinde tubers, at both 1 and 4 h after being cut. The flesh colour of cooked potatoes was characterised by low susceptibility to darkening, and purple-fleshed tubers were more saturated by chroma than tubers of red-fleshed varieties.     

Change in glutathione S-transferase and glyceraldehyde-3-phosphate dehydrogenase activities in the organs of mice treated with 2-chloroethyl ethyl sulfide or its oxidation products

We have analyzed the immediate and mid-term (1 and 2 years) results of percutaneous mitral valvuloplasty (PMV) by Inoue's catheter in 97 patients < 60 years (Group A) compared with 34 patients > 60 years (Group B). In 61% Group A the patients were in NYHA functional class II, 36% in III, and 3% in I; in Group B, 56% of the patients were in NYHA functional class III, 38% in II, and 6% in IV. Mean mitral valve area was 1.1 cm2 before dilatation in both groups, and a significant (p < 0.0001) increase was obtained in both Group A (0.9 +/- 0.3 cm2) and Group B (0.8 +/- 0.3 cm2). No significant differences were observed between the two groups. Mean transvalvular gradient decreased significantly (p < 0.0001) from 13.6 +/- 5.7 to 7.2 +/- 3.1 mmHg in Group A, and from 9.9 +/- 4 to 6.5 +/- 2.3 mmHg in Group B (A vs B: p < 0.02). Optimal result was obtained in 94% and 88% of Group A and Group B patients, respectively. Suboptimal result was obtained in 2% and 6% of Group A and Group B patients, respectively. These differences were not significant. Failure of PMV occurred in 4% and 6%, respectively. At 1-year follow-up Group A 7 patients and 5 Group B patients showed restenosis; at 2-year follow-up one more restenosis was present in Group A (A vs B at 1 and 2 years: NS). We conclude that PMV is a safe and effective technique in young patients and in patients > 60 years.