23 research outputs found
Development of a Thermal Management System for Electrified Aircraft
This paper describes the development and optimization of a conceptual thermal management system for electrified aircraft. Here, a vertical takeoff and landing (VTOL) vehicle is analyzed with the following electrically sourced heat loads considered: motors, generators, rectifiers, and inverters. The vehicle will employ liquid-cooling techniques in order to acquire, transport, and reject waste heat from the vehicle. The purpose of this paper is to threefold: 1) Present a potential modeling framework for system level thermal management system simulation, 2) Analyze typical system characteristics, and 3) Perform optimization on a system developed for a specific vehicle to minimize weight gain, power utilization, and drag. Additionally, the paper will study the design process, specifically investigating the differences between steady state and transient sizing, comparing simulation techniques with a lower fidelity option and quantifying expected error
Coronary microvascular resistance: methods for its quantification in humans
Coronary microvascular dysfunction is a topic that has recently gained considerable interest in the medical community owing to the growing awareness that microvascular dysfunction occurs in a number of myocardial disease states and has important prognostic implications. With this growing awareness, comes the desire to accurately assess the functional capacity of the coronary microcirculation for diagnostic purposes as well as to monitor the effects of therapeutic interventions that are targeted at reversing the extent of coronary microvascular dysfunction. Measurements of coronary microvascular resistance play a pivotal role in achieving that goal and several invasive and noninvasive methods have been developed for its quantification. This review is intended to provide an update pertaining to the methodology of these different imaging techniques, including the discussion of their strengths and weaknesses
Human Cytomegalovirus UL29/28 Protein Interacts with Components of the NuRD Complex Which Promote Accumulation of Immediate-Early RNA
Histone deacetylation plays a pivotal role in regulating human cytomegalovirus gene expression. In this report, we have identified candidate HDAC1-interacting proteins in the context of infection by using a method for rapid immunoisolation of an epitope-tagged protein coupled with mass spectrometry. Putative interactors included multiple human cytomegalovirus-coded proteins. In particular, the interaction of pUL38 and pUL29/28 with HDAC1 was confirmed by reciprocal immunoprecipitations. HDAC1 is present in numerous protein complexes, including the HDAC1-containing nucleosome remodeling and deacetylase protein complex, NuRD. pUL38 and pUL29/28 associated with the MTA2 component of NuRD, and shRNA-mediated knockdown of the RBBP4 and CHD4 constituents of NuRD inhibited HCMV immediate-early RNA and viral DNA accumulation; together this argues that multiple components of the NuRD complex are needed for efficient HCMV replication. Consistent with a positive acting role for the NuRD elements during viral replication, the growth of pUL29/28- or pUL38-deficient viruses could not be rescued by treating infected cells with the deacetylase inhibitor, trichostatin A. Transient expression of pUL29/28 enhanced activity of the HCMV major immediate-early promoter in a reporter assay, regardless of pUL38 expression. Importantly, induction of the major immediate-early reporter activity by pUL29/28 required functional NuRD components, consistent with the inhibition of immediate-early RNA accumulation within infected cells after knockdown of RBBP4 and CHD4. We propose that pUL29/28 modifies the NuRD complex to stimulate the accumulation of immediate-early RNAs
Human Cytomegalovirus IE1 Protein Elicits a Type II Interferon-Like Host Cell Response That Depends on Activated STAT1 but Not Interferon-Ξ³
Human cytomegalovirus (hCMV) is a highly prevalent pathogen that, upon primary
infection, establishes life-long persistence in all infected individuals. Acute
hCMV infections cause a variety of diseases in humans with developmental or
acquired immune deficits. In addition, persistent hCMV infection may contribute
to various chronic disease conditions even in immunologically normal people. The
pathogenesis of hCMV disease has been frequently linked to inflammatory host
immune responses triggered by virus-infected cells. Moreover, hCMV infection
activates numerous host genes many of which encode pro-inflammatory proteins.
However, little is known about the relative contributions of individual viral
gene products to these changes in cellular transcription. We systematically
analyzed the effects of the hCMV 72-kDa immediate-early 1 (IE1) protein, a major
transcriptional activator and antagonist of type I interferon (IFN) signaling,
on the human transcriptome. Following expression under conditions closely
mimicking the situation during productive infection, IE1 elicits a global type
II IFN-like host cell response. This response is dominated by the selective
up-regulation of immune stimulatory genes normally controlled by IFN-Ξ³ and
includes the synthesis and secretion of pro-inflammatory chemokines.
IE1-mediated induction of IFN-stimulated genes strictly depends on
tyrosine-phosphorylated signal transducer and activator of transcription 1
(STAT1) and correlates with the nuclear accumulation and sequence-specific
binding of STAT1 to IFN-Ξ³-responsive promoters. However, neither synthesis
nor secretion of IFN-Ξ³ or other IFNs seems to be required for the
IE1-dependent effects on cellular gene expression. Our results demonstrate that
a single hCMV protein can trigger a pro-inflammatory host transcriptional
response via an unexpected STAT1-dependent but IFN-independent mechanism and
identify IE1 as a candidate determinant of hCMV pathogenicity
The acute physiological effects of high- and low-velocity resistance exercise in older adults
The aim of the present study was to determine if workload matched, high-velocity (HVE) and low-velocity (LVE) resistance exercise protocols, elicit differing acute physiological responses in older adults. Ten older adults completed three sets of eight exercises on six separate occasions (three HVE and three LVE sessions). Systolic blood pressure, diastolic blood pressure and blood lactate were measured pre- and post-exercise, heart rate was measured before exercise and following each set of each exercise. Finally, a rating of perceived exertion was measured following each set of each exercise. There were no significant differences in blood lactate (F(1,9)Β =Β 0.028; PΒ =Β 0.872; Ξ·P2Β =Β 0.003), heart rate (F(1,9)Β =Β 0.045; PΒ =Β 0.837; Ξ·P2Β =Β 0.005), systolic blood pressure (F(1,9)Β =Β 0.023; PΒ =Β 0.884; Ξ·P2Β =Β 0.003) or diastolic blood pressure (F(1,9)Β =Β 1.516; PΒ =Β 0.249; Ξ·P2Β =Β 0.144) between HVE and LVE. However, LVE elicited significantly greater ratings of perceived exertion compared to HVE (F(1,9)Β =Β 13.059; PΒ =Β 0.006; Ξ·P2Β =Β 0.592). The present workload matched HVE and LVE protocols produced comparable physiological responses, although greater exertion was perceived during LVE
Capture and electrochemical conversion of CO2 in molten alkali metal borateβcarbonate blends
CO2 captured from high temperature effluent gases by molten borate salts are reduced electrochemically to form carbon nanotubes.</jats:p
Capture and Electrochemical Reduction of CO<sub>2</sub> Using Molten Alkali Metal Borates
Molten
alkali metal borates are a class of molten salts that have
recently shown promise as high-temperature sorbents for capture of
CO2 and other acid gases. Thermal swing systems based on
molten borates have demonstrated CO2 capture capacities
greater than those of amines, enabling efficient recovery of high-temperature
heat in flue gas without practical concerns commonly associated with
solid sorbents at these temperatures. In this work, we exploited generation
of carbonates upon CO2 capture by borates to enable their
use as electrolytic media for carbon nanotube (CNT) synthesis by CO2 splitting. Here, we report the conditions necessary to synthesize
valuable multiwalled CNTs by CO2 capture and conversion
as a sustainable alternative to conventional carbon-intensive CNT
synthesis techniques. Effects of cathode materials and operating conditions
are quantified in sodium lithium borate, achieving significantly higher
CO2 uptake capacities than alkali metal carbonate salts
for conversion of CO2 into CNTs in the 550β650 Β°C
range
Focused Laser Spike Dewetting as a Rheology Method for Soft Matter Thin Films
Focused laser spike (FLaSk) dewetting employs a localized heat source to create thermocapillary induced trench-ridge morphologies. By using a universal heating substrate to create a material independent thermal profile coupled with optical microscopy, we have studied the dewetted ridge feature for several distinct glassy thin films. The evolution of the ridge\u27s radius over time can be modeled using stretched exponential functions to derive a maximum dewetted radius and a characteristic decay time. The characteristic decay time shows a super-Arrhenius behavior resembling viscosity change during the glass transition process. An effective viscosity is defined by balancing the thermocapillary Marangoni stress using the mean temperature in the melt pool, indicating clear signature of composition. In this way, we have demonstrated that FLaSk dewetting as a rheologymethod can be employed for high-throughput analysis of glassy thin film materials at high temperature and shear.</div
Obtaining Thickness-Limited Electrospray Deposition for 3D Coating
Electrospray
processing utilizes the balance of electrostatic forces
and surface tension within a charged spray to produce charged microdroplets
with a narrow dispersion in size. In electrospray deposition, each
droplet carries a small quantity of suspended material to a target
substrate. Past electrospray deposition results fall into two major
categories: (1) continuous spray of films onto conducting substrates
and (2) spray of isolated droplets onto insulating substrates. A crossover
regime, or a self-limited spray, has only been limitedly observed
in the spray of insulating materials onto conductive substrates. In
such sprays, a limiting thickness emerges, where the accumulation
of charge repels further spray. In this study, we examined the parametric
spray of several glassy polymers to both categorize past electrospray
deposition results and uncover the critical parameters for thickness-limited
sprays. The key parameters for determining the limiting thickness
were (1) field strength and (2) spray temperature, related to (i)
the necessary repulsive field and (ii) the ability for the deposited
materials to swell in the carrier solvent vapor and redistribute charge.
These control mechanisms can be applied to the uniform or controllably-varied
microscale coating of complex three-dimensional objects
Obtaining Thickness-Limited Electrospray Deposition for 3D Coating
Electrospray
processing utilizes the balance of electrostatic forces
and surface tension within a charged spray to produce charged microdroplets
with a narrow dispersion in size. In electrospray deposition, each
droplet carries a small quantity of suspended material to a target
substrate. Past electrospray deposition results fall into two major
categories: (1) continuous spray of films onto conducting substrates
and (2) spray of isolated droplets onto insulating substrates. A crossover
regime, or a self-limited spray, has only been limitedly observed
in the spray of insulating materials onto conductive substrates. In
such sprays, a limiting thickness emerges, where the accumulation
of charge repels further spray. In this study, we examined the parametric
spray of several glassy polymers to both categorize past electrospray
deposition results and uncover the critical parameters for thickness-limited
sprays. The key parameters for determining the limiting thickness
were (1) field strength and (2) spray temperature, related to (i)
the necessary repulsive field and (ii) the ability for the deposited
materials to swell in the carrier solvent vapor and redistribute charge.
These control mechanisms can be applied to the uniform or controllably-varied
microscale coating of complex three-dimensional objects