Manufacturing of conductive structural composites through spraying of CNTs/epoxy dispersions on dry carbon fiber plies

In this work, multiscale Carbon Fiber-Reinforced Polymers have been manufactured by inserting carbon nanotubes in the matrix of the composite material to improve and homogenize the through-thickness electrical conductivity. A first part of this work introduces a spraying technique and manufacturing process followed to produce the CNT-doped multiscale CFRP. A quality assessment of the produced material is also presented. A second part investigates the electrical conductivity, as well as a few mechanical properties of the newly manufactured material, to be able to conclude on the viability and potential of this technique. This paper presents the further development of an earlier study presenting the thermal, rheological and electrical behavior of the CNT doped epoxy matrix (Fogel et al., 2015)

Polymerization study and rheological behavior of a RTM6 epoxy resin system during preprocessing step

Curing process and rheological behaviors of a monocomposant epoxy resin used in structural aeronautic applications are investigated. This study helped settle the basic parameters in order to optimize the infusion process of carbon fibers in an epoxy matrix. The effect of carbon nanotube dispersion during the preinjection step is also studied to improve electrical behavior of composite parts. The curing process has been analyzed at isothermal temperature using differential scanning calorimetry technique. Viscosity measurements were achieved with a Couette geometry, suitable for low viscosity resin. A shear-thinning effect caused by adding CNTs in the epoxy matrix is detected. It is more pronounced at high temperature for increasing CNT mass content

Patients with an ICD Can Safely Resume Work in Industrial Facilities Following Simple Screening for Electromagnetic Interference

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74026/1/j.1460-9592.2003.t01-1-00251.x.pd

Hematologic Involvement as a Predictor of Mortality in COVID-19 Patients in a Safety Net Hospital

Introduction: COVID-19 affects the hematologic system. This article evaluated the impact of hematologic involvement of different blood cell line parameters of white blood cells including absolute neutrophil count (ANC), hemoglobin, and platelets in COVID-19 patients and their association with hospital mortality and length of stay (LOS). Methods: This was a retrospective study of 475 patients with con- firmed positive COVID-19 infection and hematologic abnormalities in the metropolitan New York City area. Results: Elevated absolute neutrophil count (OR: 1.20; 95% CI: 1.02-1.42; p \u3c 0.05) increased days of hematologic involvement (OR: 4.44; 95% CI: 1.42-13.90; p \u3c 0.05), and persistence of hematologic involvement at discharge (OR: 2.87; 95% CI: 1.20-6.90; p \u3c 0.05) was associated with higher mortality. Higher hemoglobin at admission (OR: 0.77; 95% CI:0.60-0.98; p \u3c 0.001) and platelets peak (OR: 0.995; 95% CI: 0.992-0.997; p \u3c 0.001) were associated with decreased mor- tality. Patients with higher white blood cell peak (B = 0.46; SE = 0.07; p \u3c 0.001) and higher hemoglobin at admission (B = 0.05; SE = 0.01; p \u3c 0.001) were associated with higher LOS. Those with higher hemo- globin nadir (B = -0.06; SE = 0.01; p \u3c 0.001), higher platelets nadir (B = -0.001; SE = \u3c 0.001; p \u3c 0.001), and hematologic involvement at discharge or death (B = -0.06; SE = 0.03; p \u3c 0.05) were associated with lower LOS. Conclusions: These findings can be used by clinicians to better risk- stratify patients with hematologic involvement in COVID-19 and tailor therapies potentially to improve patient outcomes

The Far-Ultraviolet "Continuum" in Protoplanetary Disk Systems II: CO Fourth Positive Emission and Absorption

We exploit the high sensitivity and moderate spectral resolution of the $HST$-Cosmic Origins Spectrograph to detect far-ultraviolet spectral features of carbon monoxide (CO) present in the inner regions of protoplanetary disks for the first time. We present spectra of the classical T Tauri stars HN Tau, RECX-11, and V4046 Sgr, representative of a range of CO radiative processes. HN Tau shows CO bands in absorption against the accretion continuum. We measure a CO column density and rotational excitation temperature of N(CO) = 2 +/- 1 $\times$ 10$^{17}$ cm$^{-2}$ and T_rot(CO) 500 +/- 200 K for the absorbing gas. We also detect CO A-X band emission in RECX-11 and V4046 Sgr, excited by ultraviolet line photons, predominantly HI LyA. All three objects show emission from CO bands at $\lambda$ $>$ 1560 \AA, which may be excited by a combination of UV photons and collisions with non-thermal electrons. In previous observations these emission processes were not accounted for due to blending with emission from the accretion shock, collisionally excited H$_{2}$, and photo-excited H2; all of which appeared as a "continuum" whose components could not be separated. The CO emission spectrum is strongly dependent upon the shape of the incident stellar LyA emission profile. We find CO parameters in the range: N(CO) 10$^{18-19}$ cm$^{-2}$, T_{rot}(CO) > 300 K for the LyA-pumped emission. We combine these results with recent work on photo- and collisionally-excited H$_{2}$ emission, concluding that the observations of ultraviolet-emitting CO and H2 are consistent with a common spatial origin. We suggest that the CO/H2 ratio in the inner disk is ~1, a transition between the much lower interstellar value and the higher value observed in solar system comets today, a result that will require future observational and theoretical study to confirm.Comment: 12 pages, 7 figures, 3 tables. ApJ - accepte

Freedom, Servitude and Voluntary Labor

We present an economic framework to revisit and reframe some important debates over the nature of free versus unfree labor and the economic consequences of emancipation. We use a simple general equilibrium model in which labor can be either free or coerced and where land and labor will be exchanged on markets that can be competitive or manipulated or via other non-market collusive arrangements. By working with variants of the same basic model under different assumptions about initial economy-wide factor endowments and asset ownership we can compare equilibrium distributional outcomes under different institutional and contractual arrangements including markets with free labor and free tenancy, slavery, and tenancy arrangements with tied labor-service obligations. Analysis of these different contractual and organizational forms yields insights that accord with common sense, but that are often overlooked or downplayed in academic debates, particularly amongst economists

Complex organic molecules along the accretion flow in isolated and externally irradiated protoplanetary disks

The birth environment of the Sun will have influenced the physical and chemical structure of the pre-solar nebula, including the attainable chemical complexity reached in the disk, important for prebiotic chemistry. The formation and distribution of complex organic molecules (COMs) in a disk around a T Tauri star is investigated for two scenarios: (i) an isolated disk, and (ii) a disk irradiated externally by a nearby massive star. The chemistry is calculated along the accretion flow from the outer disk inwards using a comprehensive network which includes gas-phase reactions, gas-grain interactions, and thermal grain-surface chemistry. Two simulations are performed, one beginning with complex ices and one with simple ices only. For the isolated disk, COMs are transported without major chemical alteration into the inner disk where they thermally desorb into the gas reaching an abundance representative of the initial assumed ice abundance. For simple ices, COMs can efficiently form on grain surfaces under the conditions in the outer disk. Gas-phase COMs are released into the molecular layer via photodesorption. For the irradiated disk, complex ices are also transported inwards; however, they undergo thermal processing caused by the warmer conditions in the irradiated disk which tends to reduce their abundance along the accretion flow. For simple ices, grain-surface chemistry cannot efficiently synthesise COMs in the outer disk because the necessary grain-surface radicals, which tend to be particularly volatile, are not sufficiently abundant on the grain surfaces. Gas-phase COMs are formed in the inner region of the irradiated disk via gas-phase chemistry induced by the desorption of strongly bound molecules such as methanol; hence, the abundances are not representative of the initial molecular abundances injected into the outer disk. These results suggest that the composition of comets formed in isolated disks may differ from those formed in externally irradiated disks with the latter composed of more simple ices

A Hubble Space Telescope Survey of H2 Emission in the Circumstellar Environments of Young Stars

The formation timescale and final architecture of exoplanetary systems are closely related to the properties of the molecular disks from which they form. Observations of the spatial distribution and lifetime of the molecular gas at planet-forming radii (r < 10 AU) are important for understanding the formation and evolution of exoplanetary systems. Towards this end, we present the largest spectrally resolved survey of H2 emission around low-mass pre-main sequence stars compiled to date. We use a combination of new and archival far-ultraviolet spectra from the COS and STIS instruments on the Hubble Space Telescope to sample 34 T Tauri stars (27 actively accreting CTTSs and 7 non-accreting WTTSs) with ages ranging from roughly 1-10 Myr. We observe fluorescent H2 emission, excited by LyA photons, in 100 of the accreting sources, including all of the transitional disks in our sample (CS Cha, DM Tau, GM Aur, UX Tau A, LkCa15, HD 135344B and TW Hya). The spatial distribution of the emitting gas is inferred from spectrally resolved H2 line profiles. Some of the emitting gas is produced in outflowing material, but the majority of H2 emission appears to originate in a rotating disk. For the disk-dominated targets, the H2 emission originates predominately at r < 3 AU. The emission line-widths and inner molecular radii are found to be roughly consistent with those measured from mid-IR CO spectra.Comment: ApJ - accepted. 19 pages, 12 figure