Steady and Unsteady Thermo-Strucural Simulation of Thermally Actuated Micro- and Nano-Structures

This dissertation provides a thermo-structural simulation for nano-scale and micro-scale structures with pinned and fixed boundary conditions which are either thermally positioned, buckled, or actuated. The study begins with simulating a pinned-pinned beam in micro-scale and nano-scale. The steady state thermo-structural equation is solved numerically using an implicit Finite Difference method implemented in Matlab to obtain the thermal positioning response, which is the thermally steady state center displacement, by adding a constant, time-independent heat flux to the structure. The results show the steady state thermal displacement of the system is a function of the geometry, pressure, material properties, and constant heat flux in the free molecular model, while this value is independent of pressure in the continuum model. The thermal positioning simulation is used to improve the thermal efficiency of a thermal micro-switch by introducing various heating configurations. The second thermal mode is thermal buckling which is used to introduce a new thermal buckling storage nano-memory. Using an unsteady simulation, the power requirements for thermal actuations, optimal geometry, and write time of the device for various materials are investigated. The results show that this memory consume a low power in the order of 1 nJ per bit and has a data storage density of 10e11 bits/cm3,which is acceptable in comparison with the current memory devices. Thermal buckling nano-memory is also radiation-protected, making it a good alternative for space exploration computer systems operating in high radiation and electromagnetic environments. In contrast with thermal positioning and buckling, thermal actuation applies time-dependent heat load leading to vibration in the structure. An implicit Finite Difference method implemented in C++ was used to solve the coupled transient thermo-structural equations with constant thermal properties, while an explicit approach was used to solve the variable properties thermo-structural equations. The response, the center displacement in a doubly-clamped bridge, is tracked by time and decomposed to the steady state and vibration amplitudes. The results show that constant thermal properties assumption is limited for small heat additions lower than 1 mW. Thermal actuation results are applicable in simulating the dynamic behavior of nano-scale devices used for switching, nano-manufacturing, and measurement

Excess dietary tryptophan mitigates aflatoxicosis in growing quails

A biological assay was carried out to evaluate the impact of dietary tryptophan (TRP) in aflatoxin B -contaminated diets (AFB -D) on performance, blood parameters, immunity, meat quality and microbial populations of intestine in Japanese quails. Six experimental diets were formulated to include two levels of dietary TRP; 2.9 (moderate high: MH-TRP) and 4.9\ua0g/kg (excess: Ex-TRP); and three levels of AFB (0.0, 2.5, and 5.0\ua0mg/kg). Each experimental diet was fed to the one of the six groups of birds from 7 to 35\ua0days of age in a completely randomized design with 2\ua0×\ua03 factorial arrangement. Decrease in feed intake, body weight gain and gain:feed in birds fed 5.0\ua0mg/kg AFB -D was restored to the control level by 4.9\ua0g TRP/kg of the diet. The hepatic enzymes in blood were elevated in quails fed on AFB -D but attenuated by 4.9\ua0g TRP/kg of the diet (Ex-TRP; p\ua0≤\ua0.01). High serum uric acid in birds challenged with AFB significantly decreased by Ex-TRP (p\ua0≤\ua0.01). The skin thickness to 2,4-dinitro-1-chlorobenzene challenge suppressed by AFB but increased by Ex-TRP diet (p\ua0≤\ua0.02). The AFB increased the malondialdehyde in meat, whereas TRP efficiently diminished malondialdehyde production (p\ua0≤\ua0.01). The greatest drip loss and pH in meat were observed in the birds fed 5.0\ua0mg/kg AFB -D but Ex-TRP augmented the adverse effects of AFB (p\ua0≤\ua0.01). The Ex-TRP reduced the total microbial and Escherichia coli counts (p\ua0≤\ua0.01). The adverse effect of AFB on ileal Lactic acid bacteria was completely prevented by Ex-TRP (p\ua0≤\ua0.03). This study showed that tryptophan supplementation could be considered as a powerful nutritional tool to ameliorate the adverse effects of AFB in growing quails

The Active CryoCubeSat Project: Testing and Preliminary Results

The Center for Space Engineering at Utah State University and NASA’s Jet Propulsion Laboratory have jointly developed an active thermal control technology to better manage thermal loads and enable cryogenic instrumentation for CubeSats. The Active CryoCubeSat (ACCS) project utilizes a two-stage active thermal control architecture with the first stage consisting of a single-phase mechanically pumped fluid loop, which circulates coolant between a cold plate rejection heat exchanger and a deployed radiator. The second stage relies upon a miniature tactical cryocooler, which provides sub 110 K thermal management. This research details the experimental setup for a groundbased prototype demo which was tested in an appropriate, and relevant thermal vacuum environment. The preliminary results, which include the input power required by the system, rejection and environmental temperatures and the total thermal dissipation capabilities of the ACCS system, are presented along with a basic analysis and a discussion of the results

CubeSat Active Thermal Management in Support of Cooled Electro-Optical Instrumentation for Advanced Atmospheric Observing Missions

The need for advanced cooled electro-optical instrumentation in remote observations of the atmosphere is well known and demonstrated by SABER on the TIMED mission. The relatively new use of small satellites in remote earth observing missions as, well as the challenges, are epitomized by the upcoming NOAA EON-IR 12U CubeSat missions. These advanced CubeSat missions, which hope to accomplish scientific objectives on the same scale as larger more traditional satellites, require advanced miniaturized cryocoolers and active methods for thermal management and power control. The active CryoCubeSat project (ACCS) is a demonstration of such a technology. Utilizing Ultrasonic Additive Manufacturing (UAM) techniques, a Mechanical Pumped Fluid Loop (MPFL), and miniature pumps and cryocoolers to create a closed loop fluid-based heat interchange system. The ACCS project creates a two-stage thermal control system targeting 6U CubeSat platforms. The first stage is composed of a miniature Ricor K508N cryocooler while the second is formed by a UAM fabricated heat exchanger MPFL system powered by a micro TCS M510 pump. The working fluid is exchanged between a built-in chassis heat exchanger and a deployable tracking radiator. This work details the theory design and testing of a relevant ground-based prototype and the analysis and modeling of the results as well as the development of a design tool to help in customized active thermal control designs for small satellites. Ultimately, the ACCS project hopes to enable a new generation of advanced CubeSat atmospheric observing missions

Borna disease virus (BDV) infection in psychiatric patients and healthy controls in Iran

Background Borna disease virus (BDV) is an evolutionary old RNA virus, which infects brain and blood cells of humans, their primate ancestors, and other mammals. Human infection has been correlated to mood disorders and schizophrenia, but the impact of BDV on mental-health still remains controversial due to poor methodological and cross-national comparability. Method This first report from the Middle East aimed to determine BDV infection prevalence in Iranian acute psychiatric disorder patients and healthy controls through circulating immune complexes (CIC), antibodies (Ab) and antigen (pAg) in blood plasma using a standardized triple enzyme immune assay (EIA). Samples of 314 subjects (114 psychiatric cases, 69 blood donors, and 131 healthy controls) were assayed and data analyzed quantitatively and qualitatively. Results CICs revealed a BDV prevalence of one third (29.5%) in healthy Iranian controls (27.5% controls; 33.3% blood donors). In psychiatric patients CIC prevalence was higher than in controls (40.4%) and significantly correlating with bipolar patients exhibiting overt clinical symptoms (p = 0.005, OR = 1.65). CIC values were significantly elevated in bipolar (p = 0.001) and major depressive disorder (p = 0.029) patients as compared to controls, and in females compared to males (p = 0.031). Conclusion This study supports a similarly high prevalence of subclinical human BDV infections in Iran as reported for central Europe, and provides again an indication for the correlation of BDV infection and mood disorders. Further studies should address the morbidity risk for healthy carriers and those with elevated CIC levels, along with gender disparities

Ameliorative impact of ezetimibe on gentamicin-induced kidney damage; A histopathological perspective

Introduction: Gentamicin, despite its beneficial effects, has significant nephrotoxic effects that are observed in 20% of the patients. Ezetimibe is recognized as an inhibitor of cholesterol absorption. Objectives: The present study aimed to investigate the histopathological effects of ezetimibe on gentamicin-induced kidney damage. Materials and Methods: Twenty male Wistar rats were randomly divided into five groups and treated as the following; group 1 (normal group), group 2 [gentamicin group, daily 80 mg/kg, intra-peritoneal (i.p.) for seven days], group 3-5 (gentamicin 80 + ezetimibe at doses of 2.5, 12.5, and 37.5 mg/kg, respectively). Kidney sections were examined for histopathological parameters including vacuolization of the tubular renal cells, degeneration, necrosis, flattening of the tubular cells and debris in the tubular lumen. Results: Gentamicin injection significantly induced histopathological alterations (P < 0.05). Ezetimibe therapy significantly decreased the levels of vacuolization, degeneration, necrosis, flattening of the tubular cells and debris in the nephrotoxic rats (P < 0.05). Conclusion: The results illustrated that treatment with ezetimibe can improve kidney damage caused by gentamicin injection

Re-Architecting the NASA Wire Derating Approach for Space Flight Applications

Mr. Steve Rickman, NASA Technical Fellow for Passive Thermal, proposed a pathfinder study to develop an apparatus for wire and wire bundle thermal testing to measure their performance, and to support development of thermal analytical models. Development of such capability would enable wire and wire bundle amperage capacity. The goal of this study was to assess the feasibility of developing physics-based and regression thermal models of single wires and wire bundles. This report contains the outcome of the NESC assessment

Possible involvement of l-arginine-nitric oxide pathway in the antidepressant activity of Auraptene in mice

Background: Depression is one of the most common mental illnesses worldwide. Nitric oxide (NO) is involved in the pathophysiology of depression. Auraptene (a coumarin derivative) has been shown to possess pharmacological effects on neurological diseases. Purpose: The present study aimed to investigate the possible role of the NO pathway in Auraptene antidepressant effects in male mice. Methods: Behavioral tests were used to assess depression-like behaviors. The mice received Auraptene at 10, 30, and 100 mg/kg, the combination of the sub-effective (ineffective) dose of Auraptene (10 mg/kg) and L-NAME, and the combination of the effective dose of Auraptene (30 mg/kg) and L-arginine. Finally, OFT, TST, FST, brain, serum MDA level, antioxidant capacity, hippocampus, and serum NO level were measured. Results: The data analysis showed that Auraptene (30 mg/kg) improved depression-like behaviors. Auraptene (30 mg/kg) also significantly reduced serum NO levels (P < 0.05) and significantly increased serum MDA (10 mg/kg, P < 0.05). Auraptene at 30 mg/kg also increased serum antioxidant capacity (P < 0.01). Co-administration of L-NAME and the sub-effective dose of Auraptene enhanced the effects of Auraptene. However, co-administration of the effective dose of Auraptene and L-arginine reduced the impacts of Auraptene. Conclusions: The results showed that Auraptene causes antidepressant effects in a dose-dependent manner and acts as a prooxidant at 100 mg/kg, and exacerbates oxidative stress. The antidepressant effects of this active molecule are exerted by reducing the NO level in the hippocampus and serum, increasing the antioxidant capacity, and reducing the MDA level in the serum