Design And Experimental Study Of An Integrated Vapor Chamber - Thermal Energy Storage System

Future defense, aerospace and automotive technologies involve electronic systems that release high pulsed waste heat like during high power microwave and laser diode applications in tactical and combat aircraft, and electrical and electronic systems in hybrid electric vehicles, which will require the development of an efficient thermal management system. A key design issue is the need for fast charging so as not to overheat the key components. The goal of this work is to study the fabrication and technology implementation feasibility of a novel high energy storage, high heat flux passive heat sink. Key focus is to verify by theory and experiments, the practicability of using phase change materials as a temporary storage of waste heat for heat sink applications. The reason for storing the high heat fluxes temporarily is to be able to reject the heat at the average level when the heat source is off. Accordingly, a concept of a dual latent heat sink intended for moderate to low thermal duty cycle electronic heat sink applications is presented. This heat sink design combines the features of a vapor chamber with rapid thermal energy storage employing graphite foam inside the heat storage facility along with phase change materials and is attractive owing to its passive operation unlike some of the current thermal management techniques for cooling of electronics employing forced air circulation or external heat exchangers. In addition to the concept, end-application dependent criteria to select an optimized design for this dual latent heat sink are presented. A thermal resistance concept based design tool/model has been developed to analyze and optimize the design for experiments. The model showed that it is possible to have a dual latent heat sink design capable of handling 7 MJ of thermal load at a heat flux of 500 W/cm2 (over an area of 100 cm2) with a volume of 0.072 m3 and weighing about 57.5 kg. It was also found that with such high heat flux absorption capability, the proposed conceptual design could have a vapor-to-condenser temperature difference of less than 10 0C with a volume storage density of 97 MJ/m3 and a mass storage density of 0.122 MJ/kg. The effectiveness of this heat sink depends on the rapidness of the heat storage facility in the design during the pulse heat generation period of the duty cycle. Heat storage in this heat sink involves transient simultaneous laminar film condensation of vapor and melting of an encapsulated phase change material in graphite foam. Therefore, this conjugate heat transfer problem including the wall inertia effect is numerically analyzed and the effectiveness of the heat storage mechanism of the heat sink is verified. An effective heat capacity formulation is employed for modeling the phase change problem and is solved using finite element method. The results of the developed model showed that the concept is effective in preventing undue temperature rise of the heat source. Experiments are performed to investigate the fabrication and implementation feasibility and heat transfer performance for validating the objectives of the design i.e., to show that the VCTES heat sink is practicable and using PCM helps in arresting the vapor temperature rise in the heat sink. For this purpose, a prototype version of the VCTES heat sink is fabricated and tested for thermal performance. The volume foot-print of the vapor chamber is about 6 X5 X2.5 . A custom fabricated thermal energy storage setup is incorporated inside this vapor chamber. A heat flux of 40 W/cm2 is applied at the source as a pulse and convection cooling is used on the condenser surface. Experiments are done with and without using PCM in the thermal energy storage setup. It is found that using PCM as a second latent system in the setup helps in lowering the undue temperature rise of the heat sink system. It is also found that the thermal resistance between the vapor chamber and the thermal energy storage setup, the pool boiling resistance at the heat source in the vapor chamber, the condenser resistance during heat discharging were key parameters that affect the thermal performance. Some suggestions for future improvements in the design to ease its implementation and enhance the heat transfer of this novel heat sink are also presented

Screening of a Focused Ubiquitin-Proteasome Pathway Inhibitor Library Identifies Small Molecules as Novel Modulators of Botulinum Neurotoxin Type A Toxicity.

Botulinum neurotoxins (BoNTs) are known as the most potent bacterial toxins, which can cause potentially deadly disease botulism. BoNT Serotype A (BoNT/A) is the most studied serotype as it is responsible for most human botulism cases, and its formulations are extensively utilized in clinics for therapeutic and cosmetic applications. BoNT/A has the longest-lasting effect in neurons compared to other serotypes, and there has been high interest in understanding how BoNT/A manages to escape protein degradation machinery in neurons for months. Recent work demonstrated that an E3 ligase, HECTD2, leads to efficient ubiquitination of the BoNT/A Light Chain (A/LC); however, the dominant activity of a deubiquitinase (DUB), VCIP135, inhibits the degradation of the enzymatic component. Another DUB, USP9X, was also identified as a potential indirect contributor to A/LC degradation. In this study, we screened a focused ubiquitin-proteasome pathway inhibitor library, including VCIP135 and USP9X inhibitors, and identified ten potential lead compounds affecting BoNT/A mediated SNAP-25 cleavage in neurons in pre-intoxication conditions. We then tested the dose-dependent effects of the compounds and their potential toxic effects in cells. A subset of the lead compounds demonstrated efficacy on the stability and ubiquitination of A/LC in cells. Three of the compounds, WP1130 (degrasyn), PR-619, and Celastrol, further demonstrated efficacy against BoNT/A holotoxin in an in vitro post-intoxication model. Excitingly, PR-619 and WP1130 are known inhibitors of VCIP135 and USP9X, respectively. Modulation of BoNT turnover in cells by small molecules can potentially lead to the development of effective countermeasures against botulism

Psychosocial Mediators of Perceived Stigma and Suicidal Ideation among Transgender Women

BACKGROUND: Transgender women (TGW) in the U.S. experience high rates of stigma, depression, and elevated rates of suicide. This study examined correlates of suicidal ideation and estimated the conditional indirect effects of perceived stigma and psychosocial mediators on suicidal ideation. METHODS: Using a cross-sectional study design, TGW (N = 92) were recruited through snowball sampling in Atlanta, Georgia. Structured interviews were conducted. Suicidal ideation was assessed by combining two variables that measured suicidal thoughts. Logistic regression models were performed to identify the potential risk and protective factors for suicidal ideation. We examined hypothesized psychosocial factors, including anxiety, depression, psychosocial impact of gender minority status, and substance use behaviors as potential mediators for the relationship between perceived stigma and suicidal ideation. All models were controlled for age, race, education, and homelessness. RESULTS: Suicidal ideation was reported by 33% (N = 30) of the study participants. In multivariable analysis, suicidal ideation was associated with sexual abuse (AOR = 3.17, 95% CI = 1.10-9.30), anxiety (AOR = 1.74, 95% CI = 1.10-2.73), family verbal abuse (AOR = 2.99, 95% CI = 1.10-8.40), stranger verbal abuse (AOR = 3.21, 95% CI = 1.02-10.08), and psychosocial impact of gender minority status (AOR = 3.42, 95% CI = 1.81-6.46). Partner support was found to be the protective factor for suicidal ideation (AOR = 0.34, 95% CI = 0.13-0.90). In the mediation analysis, the psychosocial impact of gender minority status mediated the relationship between perceived stigma and suicidal ideation. The estimated conditional indirect effect was 0.46, (95% CI = 0.12-1.11). CONCLUSION: Interventions that aim to reduce suicidal behaviors among TGW should address stigma, psychosocial impact of gender minority status, and different forms of violence and abuse

Binding of ATP to UAP56 is necessary for mRNA export

The major-histocompatibility-complex protein UAP56 (BAT1) is a DEAD-box helicase that is deposited on mRNA during splicing. UAP56 is retained on spliced mRNA in an exon junction complex (EJC) or, alternatively, with the TREX complex at the 5\u27 end, where it might facilitate the export of the spliced mRNA to the cytoplasm. Using confocal microscopy, UAP56 was found to be concentrated in RNA-splicing speckled domains of nuclei but was also enriched in adjacent nuclear regions, sites at which most mRNA transcription and splicing occur. At speckled domains, UAP56 was in complexes with the RNA-splicing and -export protein SRm160, and, as measured by FRAP, was in a dynamic binding equilibrium. The application of an in vitro FRAP assay, in which fluorescent nuclear proteins are photobleached in digitonin-extracted cells, revealed that the equilibrium binding of UAP56 in complexes at speckled domains was directly regulated by ATP binding. This was confirmed using a point mutant of UAP56 that did not bind ATP. Point mutation of UAP56 to eliminate ATP binding did not affect RNA splicing, but strongly inhibited the export of mRNA to the cytoplasm

Miniature high speed compressor having embedded permanent magnet motor

A high speed centrifugal compressor for compressing fluids includes a permanent magnet synchronous motor (PMSM) having a hollow shaft, the being supported on its ends by ball bearing supports. A permanent magnet core is embedded inside the shaft. A stator with a winding is located radially outward of the shaft. The PMSM includes a rotor including at least one impeller secured to the shaft or integrated with the shaft as a single piece. The rotor is a high rigidity rotor providing a bending mode speed of at least 100,000 RPM which advantageously permits implementation of relatively low-cost ball bearing supports

TELEX HEBDOMADAIRE NR 186 DU 12 OCTOBRE 1984 ADRESSE A L'ENSEMBLE DES DELEGATIONS EXTERIEURES ET BUREAUX DE PRESS ET D'INFORMATION INDEPENDANTS DANS LES PAYS TIERS = WEEKLY MEMO NO. 186 ON OCTOBER 12, 1984 TO FOREIGN DELEGATIONS AND PRESS BUREAUS OF THIRD COUNTRIES

Inhibitory activities against BoNT/A LC and holotoxin in proteolytic and cell-based assay for all tested compounds; fluorescence and UV–vis spectra for determination of 16 binding to HSA and AGP; ligand interaction diagrams, docking scores, and docking–in vitro inhibitory activity correlations; spectral and analytical data for all synthesized compounds; detailed procedures for the determination of the HPLC purity.Supporting information I for: Konstantinović, J. M., Kiris, E., Kota, K. P., Kugelman-Tonos, J., Videnović, M., Cazares, L. H., Terzić-Jovanović, N., Verbić, T., Anđelković, B. D., Duplantier, A. J., Bavari, S.,& Šolaja, B. (2018). New Steroidal 4-Aminoquinolines Antagonize Botulinum Neurotoxin Serotype A in Mouse Embryonic Stem Cell Derived Motor Neurons in Postintoxication Model. Journal of Medicinal Chemistry, American Chemical Society (ACS)., 61(4), 1595-1608. [https://doi.org/10.1021/acs.jmedchem.7b01710]The published version of the article: [https://cer.ihtm.bg.ac.rs/handle/123456789/2325]The peer-reviewed version of the article: [http://cer.ihtm.bg.ac.rs/handle/123456789/2935]Additional supporting information (NMR spectra and HPLC purity spectra of all tested compounds): [https://cer.ihtm.bg.ac.rs/handle/123456789/4516]Molecular formula strings and additional data: [https://cer.ihtm.bg.ac.rs/handle/123456789/4517

VTXO: The Virtual Telescope for X-ray Observations

The Virtual Telescope for X-ray Observations (VTXO) will use lightweight Phase Frensel Lenses (PFLs) in a virtual X-ray telescope with 1 km focal length and with nearly 50 milli-arc second angular resolution. Laboratory characterization of PFLs have demonstrated near diffraction-limited angular resolution in the X-ray band, but they require long focal lengths to achieve this quality of imaging. VTXO is formed by using precision formation flying of two SmallSats: a smaller, 6U OpticsSat that houses the PFLs and navigation beacons while a larger, ESPA-class DetectorSat contains an X-ray camera, a charged-particle radiation monitor, a precision star tracker, and the propulsion for the formation flying. The baseline flight dynamics uses a highly-elliptical supersynchronous geostationary transfer orbit to allow the inertial formation to form and hold around the 90,000 km apogee for 10 hours of the 32.5-hour orbit with nearly a year mission lifetime. The guidance, navigation, and control (GN&C) for the formation flying uses standard CubeSat avionics packages, a precision star tracker, imaging beacons on the OpticsSat, and a radio ranging system that also serves as an inter-satellite communication link. VTXO’s fine angular resolution enables measuring the environments nearly an order of magnitude closer to the central engines of bright compact X-ray sources compared to the current state of the art. This X-ray imaging capability allows for the study of the effects of dust scattering nearer to the central objects such as Cyg X-3 and GX 5-1, for the search for jet structure nearer to the compact object in X-ray novae such as Cyg X-1and GRS 1915+105, and for the search for structure in the termination shock of in the Crab pulsar wind nebula. In this paper, the VTXO science performance, SmallSat and instrument designs, and mission description is described. The VTXO development was supported as one of the selected 2018 NASA Astrophysics SmallSat Study (AS3) missions

Supporting Information II for: "New Steroidal 4-Aminoquinolines Antagonize Botulinum Neurotoxin Serotype A in Mouse Embryonic Stem Cell Derived Motor Neurons in Postintoxication Model"

NMR spectra and HPLC purity spectra of all tested compoundsSupporting information II for: Konstantinović, J. M., Kiris, E., Kota, K. P., Kugelman-Tonos, J., Videnović, M., Cazares, L. H., Terzić-Jovanović, N., Verbić, T., Anđelković, B. D., Duplantier, A. J., Bavari, S.,& Šolaja, B. (2018). New Steroidal 4-Aminoquinolines Antagonize Botulinum Neurotoxin Serotype A in Mouse Embryonic Stem Cell Derived Motor Neurons in Postintoxication Model. Journal of Medicinal Chemistry, American Chemical Society (ACS)., 61(4), 1595-1608. [https://doi.org/10.1021/acs.jmedchem.7b01710]The published version of the article: [https://cer.ihtm.bg.ac.rs/handle/123456789/2325]The peer-reviewed version of the article: [http://cer.ihtm.bg.ac.rs/handle/123456789/2935]Additional supporting information: [https://cer.ihtm.bg.ac.rs/handle/123456789/4515]Molecular formula strings and additional data: [https://cer.ihtm.bg.ac.rs/handle/123456789/4517

Telomerase enzymatic component hTERT shortens long telomeres in human cells

Telomere lengths are tightly regulated within a narrow range in normal human cells. Previous studies have extensively focused on how short telomeres are extended and have demonstrated that telomerase plays a central role in elongating short telomeres. However, much about the molecular mechanisms of regulating excessively long telomeres is unknown. In this report, we demonstrated that the telomerase enzymatic component, hTERT, plays a dual role in the regulation of telomere length. It shortens excessively long telomeres and elongates short telomeres simultaneously in one cell, maintaining the optimal telomere length at each chromosomal end for efficient protection. This novel hTERT-mediated telomere-shortening mechanism not only exists in cancer cells, but also in primary human cells. The hTERT-mediated telomere shortening requires hTERT’s enzymatic activity, but the telomerase RNA component, hTR, is not involved in that process. We found that expression of hTERT increases telomeric circular DNA formation, suggesting that telomere homologous recombination is involved in the telomere-shortening process. We further demonstrated that shelterin protein TPP1 interacts with hTERT and recruits hTERT onto the telomeres, suggesting that TPP1 might be involved in regulation of telomere shortening. This study reveals a novel function of hTERT in telomere length regulation and adds a new element to the current molecular model of telomere length maintenance

Supplementary data for the article: Konstantinović, J.; Kiris, E.; Kota, K. P.; Kugelman-Tonos, J.; Videnović, M.; Cazares, L. H.; Terzić Jovanović, N.; Verbić, T. Ž.; Andjelković, B.; Duplantier, A. J.; et al. New Steroidal 4-Aminoquinolines Antagonize Botulinum Neurotoxin Serotype A in Mouse Embryonic Stem Cell Derived Motor Neurons in Postintoxication Model. Journal of Medicinal Chemistry 2018, 61 (4), 1595–1608. https://doi.org/10.1021/acs.jmedchem.7b01710

Supplementary material for: [https://doi.org/10.1021/acs.jmedchem.7b01710]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2099