Cholesterol autoxidation in phospholipid membrane bilayers

Lipid peroxidation in unilamellar liposomes of known cholesterol-phospholipid composition was monitored under conditions of autoxidation or as induced by a superoxide radical generating system, γ-irradiation or cumene hydroperoxide. Formation of cholesterol oxidation products was indexed to the level of lipid peroxidation. The major cholesterol oxidation products identified were 7-keto-cholesterol, isomeric cholesterol 5,6-epoxides, isomeric 7-hydroperoxides and isomeric 3,7-cholestane diols. Other commonly encountered products included 3,5-cholestadiene-7-one and cholestane-3β,5α,6β-triol. Superoxide-dependent peroxidation required iron and produced a gradual increase in 7-keto-cholesterol and cholesterol epoxides. Cholesterol oxidation was greatest in liposomes containing high proportions of unsaturated phospholipid to cholesterol (4∶1 molar ratio), intermediate with low phospholipid to cholesterol ratios (2∶1) and least in liposomes prepared with dipalmitoylphosphatidylcholine and cholesterol. This relationship held regardless of the oxidizing conditions used. Cumene hydroperoxide-dependent lipid peroxidation and/or more prolonge oxidations with other oxidizing systems yielded a variety of products where cholesterol-5β,6β-epoxide, 7-ketocholesterol and the 7-hydroperoxides were most consistently elevated. Oxyradical initiation of lipid peroxidation produced a pattern of cholesterol oxidation products distinguishable from the pattern derived by cumene hydroperoxide-dependent peroxidation. Our findings indicate that cholesterol autoxidation in biological membranes is modeled by the peroxide-induced oxidation of liposomes bearing unsaturated fatty acids and suggest that a number of cholesterol oxidation products are derived from peroxide-dependent propagation reactions occurring in biomembranes.     

Stearidonic Acid Increases the Red Blood Cell and Heart Eicosapentaenoic Acid Content in Dogs

Plant sources of omega-3 fatty acids (FA) are needed that can materially raise tissue levels of long-chain omega-3 FA [i.e., eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 20:6n-3)]. Stearidonic acid (SDA; 18:4n-3) is the delta-6 desaturase product of alpha-linolenic acid (ALA; 18:3n-3), and when fed to humans, increases red blood cell (RBC) content of EPA to a greater extent than does ALA. This study was undertaken to determine the dose-dependence and time course of the increase in the EPA and DHA content of the heart and RBC in dogs. Adult male Beagles were fed 21, 64, or 193 mg/kg of SDA in in their food daily for up to 12 weeks. Positive and negative controls were given EPA (43 mg/kg) or high oleic acid sunflower oil, respectively. The baseline EPA content of RBC was 0.38 ± 0.03% which increased (P < 0.01) in a dose-dependent manner, with the high dose of SDA and EPA achieving levels of 1.33 ± 0.26 and 1.55. ± 0.28%, respectively. In the heart, the content of EPA rose from 0.06 ± 0.01 to 1.24 ± 0.22% in the EPA group and to 0.81 ± 0.32% in the high SDA group (both P < 0.01). In both tissues, DHA did not change. Compared to dietary EPA, SDA was 20–23% as efficient in raising tissue EPA levels. In conclusion, SDA supplementation increased the EPA content of RBC and heart and may have utility as a plant-based source of omega-3 FA.     

A genetic technique for robotic trajectory planning

There are many multi-stage optimization problems that are not easily solved through any known direct method when the stages are coupled. For instance, the problem of planning a vehicle's control sequence to negotiate obstacles and reach a goal in minimum time is investigated. The vehicle has a known mass, and the controlling forces have finite limits. A genetic programming technique is developed that finds admissible control trajectories that tend to minimize the vehicle's transit time through the obstacle field. The immediate application is that of a space robot that must rapidly traverse around two or three dimensional structures via application of a rotating thruster or non-rotating on-off thrusters. (An air-bearing floor test-bed for such vehicles is located at the Marshal Space Flight Center in Huntsville, Alabama.) It appears that the developed method is applicable to a general set of optimization problems in which the cost function and the multi-dimensional multi-state system can be any non-linear functions that are continuous in the operating regions. Other applications include: the planning of optimal navigation pathways through a traversability graph, the planning of control input for underwater maneuvering vehicles which have complex control state-space relationships, the planning of control sequences for milling and manufacturing robots, the planning of control and trajectories for automated delivery vehicles, and the optimization of control for racing vehicles and athletic training in slalom sports.     

Photon-assisted synthesis of ultra-thin yttria-doped zirconia membranes: Structure, variable temperature conductivity and micro-fuel cell devices

We report on the synthesis and functional properties of nanoscale (50 nm) dense Y-doped zirconia (YDZ) electrolyte thin films by photon-assisted oxidation of Zr–Y precursor alloy thin films. Crystalline zirconia films with grain size of 5 nm were successfully grown at room temperature by oxidation under ultra-violet (UV) photon irradiation. Microstructure of the films was characterized by transmission electron microscopy. The electrochemical conductivity of UV grown YDZ electrolytes was investigated over a broad range of temperatures using Pt electrodes as a function of yttria doping concentration. The slightly lower electrical conductivity in UV grown films at intermediate temperature range (400–550 °C) is consistent with previous reports on oxygen defect annihilation under photo-excitation. Micro-fuel cells utilizing such ultra-thin YDZ membranes yielded 12 mW cm⁻² power density at 550 °C. The results are of potential relevance in advancing low temperature ultra-thin oxide membrane synthesis for energy applications.     

Hydrogen production in steam reforming of glycerol by conventional and membrane reactors

The aim of this study is to produce hydrogen through the glycerol steam reforming process. The reaction is carried out in a traditional reactor and an electrolessly plated Pd/Ag alloy membrane reactor, with varying reaction temperature, weight hourly specific velocity (WHSV) and water glycerol molar ratio (WGMR). The non-catalytic test was also employed for comparative purposes. The results show that the reaction is highly depending on temperature, and the maximum glycerol conversion achieved to 96.24% at 800 °C with a hydrogen yield of 5.82 mol-H₂/mol-C₃H₈O₃. It also found that the Pd/Ag membrane can effectively separate hydrogen from the reaction side and subsequently enhance the reaction rate in the membrane reactor. TGA measurements were employed to quantify the amounts of deposited carbon and the results also confirmed that the CeO₂ modified catalyst can improve the carbon resistance as well as activity and stability.     

Probabilistic seismic damage assessment of reinforced concrete buildings considering directionality effects

Most of buildings and structures are usually projected according to two main axes. However, the geographical position of these buildings varies randomly. Such random distributions of the azimuthal positions of structures, in most of the cities, generally, are not accounted for when assessing their seismic risk; certainly, the direction of the seismic loads is another highly random variable. Moreover, an additional important source of uncertainty is related to the structural response, mainly due to the random character of the mechanical properties. There is a consensus that uncertainties must be considered for adequately assessing the seismic risk of structures, but these directionality effects have not been deeply explored so far. In this article, the influence of the high uncertainty involved in these input variables on the expected seismic damage is analysed. Thus, an actual earthquake, which affected the southern part of Spain, is studied. Notably, damages on a group of affected buildings, located close to the epicentre, are analysed and discussed in detail. The results show that the influence of the random azimuthal position of structures is an important source of uncertainty and that it should be taken into account when estimating the expected seismic risk in urban areas.     

The latent learning model to derive semantic relations of words from unstructured text data in social media

Multimedia Tools and Applications - Unstructured text data is very important in many applications because it reflects the thought of the people who create this data. However, it is difficult to...     

Investigation on mining subsidence over Appin–West Cliff Colliery using time-series SAR interferometry

Advanced Time Series InSAR (ATS-InSAR) generally refers to those TS-InSAR methods with an external distributed scatterer selection module, e.g. SqueeSAR?, and GEOS-ATSA (Advanced Time-Series Analysis). It is being known as a very efficient tool for monitoring ground deformation over suburban or non-urban regions with great success. However, research conducted using C-band Envisat-based ATS-InSAR failed to produce reasonable outcome within Appin Colliery primarily due to the underground mining effect, which is located in the southeastern corner of the Southern Coalfield, New South Wales, Australia; thus, the general underground mining pattern cannot be formed. This work presents a modified ATS-InSAR method for mapping the ground deformation over underground mining region. More specifically, in order to achieve the best outcome, a modified measurement scatterer (MS) pixel selection method is introduced by including less reliable MS pixels through an Inverse Distance Weighted-based integration method. In addition, the proposed method is also applied to C-band Sentinel-1 image stacks for testing purpose, and the final result proved to be efficient to offer sufficient information to the mining industry and government for risk management purpose.