Investigations on mode-division multiplexed free-space optical transmission for inter-satellite communication link

Wireless Networks - Inter-satellite data transmission links are very crucial for providing global inter-connectivity. We report designing and investigations on high date rate inter-satellite...     

Microfluidic Tumor-on-a-Chip Model to Study Tumor Metabolic Vulnerability

Tumor-specific metabolic adaptations offer an interesting therapeutic opportunity to selectively destroy cancer cells. However, solid tumors also present gradients of nutrients and waste products across the tumor mass, forcing tumor cells to adapt their metabolism depending on nutrient availability in the surrounding microenvironment. Thus, solid tumors display a heterogenous metabolic phenotype across the tumor mass, which complicates the design of effective therapies that target all the tumor populations present. In this work, we used a microfluidic device to study tumor metabolic vulnerability to several metabolic inhibitors. The microdevice included a central chamber to culture tumor cells in a three-dimensional (3D) matrix, and a lumen in one of the chamber flanks. This design created an asymmetric nutrient distribution across the central chamber, generating gradients of cell viability. The results revealed that tumor cells located in a nutrient-enriched environment showed low to no sensitivity to metabolic inhibitors targeting glycolysis, fatty acid oxidation, or oxidative phosphorylation. Conversely, when cell density inside of the model was increased, compromising nutrient supply, the addition of these metabolic inhibitors disrupted cellular redox balance and led to tumor cell death.     

Modeling of ion transport reactor for oxy‐fuel combustion

This paper aims at investigating the performance of a cylindrical ion transport reactor designed for oxy‐fuel combustion. The cylindrical reactor walls are made of dense, nonporous, mixed‐conducting ceramic membranes that only allow oxygen permeation from the outside air into the combustion chamber. The sweep gas (CO₂ and CH₄) enters the reactor from one side and mixes with the oxygen permeate, and the products are discharged from the other side. The process of oxygen permeation through the reactor walls is influenced by the flow condition and composition of air at the feed side (inlet air side) and the gas mixture at the permeate side (sweep gas side). The modeling of the flow process is based on the numerical solution of the conservation equations of mass, momentum, energy, and species in the axisymmetric flow domain. The membrane is modeled as a selective layer in which the oxygen permeation depends on the prevailing temperatures as well as the oxygen partial pressure at both sides of the membrane. The CFD calculations were carried out using fluent 12.1 (ANSYS, Inc., Canonsburg, PA, USA), whereas the mass transfer of oxygen through the membrane is modeled by a set of user defined functions. The model results were validated against previous experimental data, and the comparison showed a good agreement. The study focused on the effect of oxygen partial pressure and temperature on the resulting combustion zones inside the reactor for the two cases of co‐current and counter‐current flow regimes. The results indicated that the oxygen to fuel mass ratio increases as the percentage of CO₂ increases in the inflow sweep gas for both co‐current and counter‐current flows. The obtained sweep mixture ratio (CO₂/CH₄) of 24 is found within the stoichiometric limit over most of the reactor length in the co‐current configuration, whereas the sweep mixture ratio of 15.67 is found in the counter‐current configuration owing to the high O₂ permeation. Copyright © 2012 John Wiley & Sons, Ltd.     

A light and electron microscopic study of cytoplasmic phospholipase A2 and cyclooxygenase-2 in the hippocampus after kainate lesions

Tamoxifen, the major adjuvant drug treatment for estrogen-dependent breast cancer, has been shown previously to affect both estrogen-dependent and calcium/calmodulin-dependent pathways. In the current study, we developed an in vitro slice system to study the effects of tamoxifen on ATP levels in hypothalamic (HTH) and preoptic areas (POA) of the rat brain. Baseline data showed that, following a 2-h incubation, HTH and POA slices had comparable ATP levels to hippocampal slices, a system used extensively by researchers examining the metabolic responsiveness of the hippocampal region (HPC) of the brain. HTH-POA slice ATP levels remained steady for 2, 4 and 6 h, but fell to 11% of initial levels by 12 h. Neurons from HTH-POA slices incubated for 4 h appeared healthy and demonstrated robust protein synthesis as measured autoradiographically by incorporation of [3H]leucine. We explored the effects of tamoxifen (TAM), fluphenazine (FLU) and estradiol (E2) on ATP levels in HTH and POA slices. The effects of TAM were complex: a 4-h incubation with 10-6 M TAM led to decreased ATP levels in HTH (but not POA), and a 4-h incubation with 10-8 M led to increased ATP levels in POA (but not HTH); a 15-min exposure to 10-6 M TAM decreased ATP levels in POA (but not HTH) slices, while the exposure of slices to the lower concentration of TAM was without effect in either area. As with higher concentrations of TAM, 4-h incubation with 10-6 M FLU decreased ATP levels in HTH (but not POA), while incubation with E2 did not affect slice ATP levels. These data are consistent with the hypothesis that both TAM and FLU alter ATP levels in HTH slices via calmodulin- or calcium-mediated processes.     

Microfabrication of submicron nozzles in silicon nitride

A novel microfabrication process is described for obtaining nanometer apertures in highly cusped nozzle-like structures fabricated in silicon nitride, having apex angles of up to a few degrees. The process is based on a sacrificial etch technology using single-crystal silicon as the mold and silicon nitride as the material for the nozzle. The nitride coating on the apex of the pyramid shaped mold is selectively etched off using a polymer layer as the etch mask, which leaves the tip of the silicon mold protruding from the masked nitride, thus defining the aperture of the nozzles. The silicon mold is then removed in an alkaline etchant, which leaves the freestanding nozzles. The process is applicable to fabrication of similar structures in a variety of other materials such as silicon dioxide, boron-doped silicon, polysilicon, and refractory and noble metals. The main requirement is the preferential etchability of the mold with respect to material for the nozzles     

Acacia albida Seed Oil: Characterization of Coronaric Acid

Coronaric acid makes up 7.8% of Acacia albida (leguminosae) oil triglycerides. Direct acetolysis of the oil followed by saponification gave cis-9,10-dihydroxyoctadec-cis-12-enoic acid which was characterized by various spectroscopic studies and chemical transformations. Quantitation of the coronaric acid was done by gas-liquid chromatography. Chrysanthemum coronarium seed oil was used as the reference standard throughout the study.     

Singular solution of a water wave problem in an ocean of finite depth

The Green's Function of a Water Wave Problem for an Ocean of Finite Depth, bounded internally by a circular cylinder, has been obtained by the use of an appropriate Fourier Series. The technique employed in this investigation may be used when the liquid is internally bounded by cylindrical regions of the form D × I where D is any two dimensional region in the undisturbed free surface and I is the linear interval [0, h].     

Modeling and Performance Analysis of 400 Gbps CO-OFDM Based Inter-satellite Optical Wireless Communication (IsOWC) System Incorporating Polarization Division Multiplexing with Enhanced Detection

Wireless Personal Communications - In this work, we report the designing and simulative analysis of a novel 400 Gbps coherent detection-orthogonal frequency division multiplexing (CO-OFDM) based...     

Flexible neural network for fast and accurate road scene perception

Accurate object detection on the road is the most important requirement of autonomous vehicles. Extensive work has been accomplished for car, pedestrian, and cyclist detection; however, comparatively, very few efforts have been put into 2D object detection. In this article, a dynamic approach is investigated to design a perfect unified neural network that could achieve the best results based on our available hardware. The proposed architecture is based on CSPNet for feature extraction in an end-to-end way. The net extracts visual features by using backbone subnet, visual object detection is based on a feature pyramid network (FPN). In order to increase the net flexibility, an auto-anchor generating method is applied to the detection layer that makes the net suitable for any datasets. For fine-tuning the net, activation, optimization, and loss functions are considered along with multiple check points. The proposed net is trained and tested based on the benchmark KITTI dataset. Our extensive experiments show that the proposed model for visual object detection is superior to others, where other nets output very low accuracy for pedestrian and cyclist detection, our proposed model achieves 99.3% recall rate based on our dataset.