Assemblies of Nanoparticles as 3D Scaffolds for New Materials Design: from Polymer Crosslinked Aerogels to Polymer Matrix Composites

From a materials perspective, nanotechnology furnishes materials with useful macroscopic properties by manipulating matter in the 1-100 nm size regime. Improvements in performance in terms of strength, modulus and wetability are accomplished by, for example, introducing nanoparticles as fillers in plastics . Two issues that usually interfere with optimal materials performance are agglomeration of the nanoparticles and materials compatibility. Agglomeration cancels the advantage of using nanoparticulate matter as dopant, while lack of materials compatibility introduces a discontinuity at the polymer/dopant interface from where failure may begin. Agglomeration is encountered with surfactants that keep nanoparticles dispersed, while materials compatibility is improved by chemical bonding of the filler with the polymer. Overall the criterion for success is enhancement of the materials properties beyond what is obtained by simple mixing nanoparticles in the matrix. Silica is the most common dopant in use as a filler in plastics. Silica derived through a base-catalyzed sol-gel process consists of interconnected string of nanoparticles dispersed randomly in the 3D space, leaving up to \u3e99% empty mesoporous space between the nanoparticle network. If we consider providing those mesoporous surfaces with functional groups capable of covalent bonding with a polymer formed from monomers introduced in the mesopores, then we can achieve two extreme structures with distinct materials properties: (a) at one end, we may deposit only a thin conformal polymer layer on the nanoparticle network; while, (b) at the other end, we may grow enough polymer to fill the mesopores completely. The first kind of structure emphasizes the materials properties deriving from the porosity, that is lightweight, low thermal conductivity and dielectric constants, and high acoustic impedance. The second kind of structure refers to nanoparticle/matrix polymer composites tackling both issues of dispersion and covalent bonding between matrix and dopant all at once

Ascaris worm in the intercostal drainage bag: inadvertent intercostal tube insertion into jejunum: a case report

Inadvertent insertion of the intercostal tube into abdomen is not rare. It can present by different ways. In the present case an Ascaris worm crept into the intercostal drainage bag to reveal the false passage of the tube

Reproductive biology of rock oyster, Saccostrea cucullata (Born, 1778) along Aare-Ware rocky shore of Ratnagiri, Maharashtra, India

802-809The present study regarding the reproductive biology of Saccostrea cucullata was carried out from May 2014 to April 2016. The observation has indicated that the peak spawning season is from the month of November to January along the Aare-Ware rocky shore of Ratnagiri. For females, the maximum values of Gonado Somatic Index (GSI) were observed in November 2014 (2.8890) and November 2015 (2.9910), whereas in males, GSI values were maximum in November 2014 (2.1964) and December 2015 (2.1681). During the study, the average male: female sex ratio of 1:1.4 was observed, with a minimum of 1:1 in the month of April 2015 and a maximum (1:1.8) during December 2014, indicating predominance of females in all the months. The size of the first maturity has been estimated to be 22.2 mm which can be utilized for signifying management measures for sustainable utilization of the resource

Reproductive biology of rock oyster, Saccostrea cucullata (Born, 1778) along Aare-Ware rocky shore of Ratnagiri, Maharashtra, India

The present study regarding the reproductive biology of Saccostrea cucullata was carried out from May 2014 to April 2016. The observation has indicated that the peak spawning season is from the month of November to January along the Aare-Ware rocky shore of Ratnagiri. For females, the maximum values of Gonado Somatic Index (GSI) were observed in November 2014 (2.8890) and November 2015 (2.9910), whereas in males, GSI values were maximum in November 2014 (2.1964) and December 2015 (2.1681). During the study, the average male: female sex ratio of 1:1.4 was observed, with a minimum of 1:1 in the month of April 2015 and a maximum (1:1.8) during December 2014, indicating predominance of females in all the months. The size of the first maturity has been estimated to be 22.2 mm which can be utilized for signifying management measures for sustainable utilization of the resource

GROWTH on S190814bv: Deep Synoptic Limits on the Optical/Near-infrared Counterpart to a Neutron Star-Black Hole Merger

On 2019 August 14, the Advanced LIGO and Virgo interferometers detected the high-significance gravitational wave (GW) signal S190814bv. The GW data indicated that the event resulted from a neutron star-black hole (NSBH) merger, or potentially a low-mass binary BH merger. Due to the low false-alarm rate and the precise localization (23 deg2 at 90%), S190814bv presented the community with the best opportunity yet to directly observe an optical/near-infrared counterpart to an NSBH merger. To search for potential counterparts, the GROWTH Collaboration performed real-time image subtraction on six nights of public Dark Energy Camera images acquired in the 3 weeks following the merger, covering >98% of the localization probability. Using a worldwide network of follow-up facilities, we systematically undertook spectroscopy and imaging of optical counterpart candidates. Combining these data with a photometric redshift catalog, we ruled out each candidate as the counterpart to S190814bv and placed deep, uniform limits on the optical emission associated with S190814bv. For the nearest consistent GW distance, radiative transfer simulations of NSBH mergers constrain the ejecta mass of S190814bv to be M ej < 0.04 M o˙ at polar viewing angles, or M ej < 0.03 M o˙ if the opacity is κ < 2 cm2g-1. Assuming a tidal deformability for the NS at the high end of the range compatible with GW170817 results, our limits would constrain the BH spin component aligned with the orbital momentum to be χ < 0.7 for mass ratios Q < 6, with weaker constraints for more compact NSs. © 2020. The American Astronomical Society

The population of merging compact binaries inferred using gravitational waves through GWTC-3

We report on the population properties of 76 compact binary mergers detected with gravitational waves below a false alarm rate of 1 per year through GWTC-3. The catalog contains three classes of binary mergers: BBH, BNS, and NSBH mergers. We infer the BNS merger rate to be between 10 $\rm{Gpc^{-3} yr^{-1}}$ and 1700 $\rm{Gpc^{-3} yr^{-1}}$ and the NSBH merger rate to be between 7.8 $\rm{Gpc^{-3}\, yr^{-1}}$ and 140 $\rm{Gpc^{-3} yr^{-1}}$ , assuming a constant rate density versus comoving volume and taking the union of 90% credible intervals for methods used in this work. Accounting for the BBH merger rate to evolve with redshift, we find the BBH merger rate to be between 17.9 $\rm{Gpc^{-3}\, yr^{-1}}$ and 44 $\rm{Gpc^{-3}\, yr^{-1}}$ at a fiducial redshift (z=0.2). We obtain a broad neutron star mass distribution extending from $1.2^{+0.1}_{-0.2} M_\odot$ to $2.0^{+0.3}_{-0.3} M_\odot$. We can confidently identify a rapid decrease in merger rate versus component mass between neutron star-like masses and black-hole-like masses, but there is no evidence that the merger rate increases again before 10 $M_\odot$. We also find the BBH mass distribution has localized over- and under-densities relative to a power law distribution. While we continue to find the mass distribution of a binary's more massive component strongly decreases as a function of primary mass, we observe no evidence of a strongly suppressed merger rate above $\sim 60 M_\odot$. The rate of BBH mergers is observed to increase with redshift at a rate proportional to $(1+z)^{\kappa}$ with $\kappa = 2.9^{+1.7}_{-1.8}$ for $z\lesssim 1$. Observed black hole spins are small, with half of spin magnitudes below $\chi_i \simeq 0.25$. We observe evidence of negative aligned spins in the population, and an increase in spin magnitude for systems with more unequal mass ratio

Search for continuous gravitational wave emission from the Milky Way center in O3 LIGO--Virgo data

We present a directed search for continuous gravitational wave (CW) signals emitted by spinning neutron stars located in the inner parsecs of the Galactic Center (GC). Compelling evidence for the presence of a numerous population of neutron stars has been reported in the literature, turning this region into a very interesting place to look for CWs. In this search, data from the full O3 LIGO--Virgo run in the detector frequency band $[10,2000]\rm~Hz$ have been used. No significant detection was found and 95$\%$ confidence level upper limits on the signal strain amplitude were computed, over the full search band, with the deepest limit of about $7.6\times 10^{-26}$ at $\simeq 142\rm~Hz$. These results are significantly more constraining than those reported in previous searches. We use these limits to put constraints on the fiducial neutron star ellipticity and r-mode amplitude. These limits can be also translated into constraints in the black hole mass -- boson mass plane for a hypothetical population of boson clouds around spinning black holes located in the GC.Comment: 25 pages, 5 figure