Physicomechanical and Antimicrobial Characteristics of Cement Composites with Selected Nano-Sized Oxides and Binary Oxide Systems

In recent years, increasing attention has been paid to the durability of building materials, including those based on cementitious binders. Important aspects of durability include the increase of the strength of the cement matrix and enhancement of material resistance to external factors. The use of nanoadditives may be a way to meet these expectations. In the present study, zinc, titanium and copper oxides, used in single and binary systems (to better the effect of their performance), were applied as additives in cement mortars. In the first part of this work, an extensive physicochemical analysis of oxides was carried out, and in the second, their application ranges in cement mortars were determined. The subsequent analyses were employed in determining the physicochemical properties of pristine oxides: Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray fluorescence (EDXRF), scanning electron microscopy (SEM), measurement of the particle size distribution, as well as zeta potential measurement depending on the pH values. Influence on selected physicomechanical parameters of the cement matrix and resistance to the action of selected Gram-positive and Gram-negative bacteria and fungi were also examined. Our work indicated that all nanoadditives worsened the mechanical parameters of mortars during the first 3 days of hardening, while after 28 days, an improvement was achieved for zinc and titanium(IV) oxides. Binary systems and copper(II) oxide deteriorated in strength parameters throughout the test period. In contrast, copper(II) oxide showed the best antibacterial activity among all the tested oxide systems. Based on the inhibitory effect of the studied compounds, the following order of microbial susceptibility to inhibition of growth on cement mortars was established (from the most susceptible, to the most resistant): E. coli < S. aureus < C. albicans < B. cereus = P. aeruginosa < P. putida.

Sorption of cobalt and zinc from single and binary metal solutions by Evernia prunastri

Non-living lichen Evernia prunastri was studied as biosorbent material for zinc and cobalt removal from single and binary metal solutions. Sorption equilibrium of Zn2+ and Co2+ ions was reached within 1 hour. Both cobalt and zinc biosorption was not pH dependent within the range pH 4-6 and negligible at pH 2. The experimental results were fitted to the Langmuir, Freundlich, Redlich-Peterson and Langmuir-Freundlich adsorption isotherms to obtain the characteristic parameters of each model. The Langmuir, Redlich-Peterson and Langmuir-Freundlich isotherms were found to well represent the measured sorption data. According to the evaluation using the Langmuir equation, the maximum sorption capacities of metal ions onto lichen biomass were 112 μmol/g Zn and 97.2 μmol/g Co from single metal solutions. E. prunastri exhibited preferential uptake of zinc from equimolar binary Zn2+ - Co2+ mixtures within the range 50 – 4000 μM. Even thought mutual interference was seen in all Co-Zn binary systems. To evaluate the two-metal sorption system, simple curves had to be replaced by three-dimensional sorption surface. These results can be used to elucidate the behavior of lichens as bioindicators of cobalt and zinc pollution in water and terrestrial ecosystems.

New Massive Contacting Twin Binary in a Radio-quiet HII Region Associated with the M17 Complex

Early-B stars, much less energetic than O stars, may create an HII region that appears as radio-quiet. We report the identification of new early-B stars associated with the radio-quiet HII region G014.645--00.606 in the M17 complex. The ratio-quiet HII region G014.645--00.606 is adjacent to three radio-quiet WISE HII region candidates \citep{2014ApJS..212....1A}. The ionizing sources of the radio-quiet HII regions are expected to later than B1V, given the sensitivity about 1-2 mJy of the MAGPIS 20 cm survey. The stars were first selected if their parallaxes of GAIA EDR3 match that of the 22 GHz H2O maser source within the same region. We used the color-magnitude diagram made from the ZTF photometric catalog to select the candidates for massive stars because the intrinsic g-r colors of massive stars change little from B-type to O-type stars. Five stars lie in the areas of the color-magnitude diagram where either reddened massive stars or evolved post-main sequence stars of lower masses are commonly found. Three of the five stars, sources 1, 2, and 3, are located at the cavities of the three IR bubbles, and extended Hα emission is detected around the three IR bubbles. We suggest that sources 1, 2, and 3 are candidates for early-B stars associated with the radio-quiet region G014.645--00.606. Particularly, source 1 is an EW type eclipsing binary with a short period of 0.825 day, while source 2 is an EA type eclipsing binary with a short period of 0.919 day. The physical parameters of the two binary systems have been derived through the PHOEBE model. Source 1 is a twin binary of two stars with Teff ≈ 23,500 K, and source 2 contains a hotter component (Teff≈20,100 K) and a cooler one (Teff≈15,500 K). The O-C values of source 1 show a trend of decline, implying that the period of source is deceasing. Source 1 is likely a contacting early-B twin binary, for which mass transfer might cause its orbit to shrink.

Numerical Simulation of Compact Objects in Binary Systems Post-Supernova

We explore the post-supernova (SN) outcomes of binary systems using a rapid stellar evolution code to simulate the equivalent of a population of ∼ 106 M ⊙. Here we explore the fraction of binaries that remain intact after the SN, which can potentially be found within supernova remnants. Given the challenges that the observational studies are facing, we use numerical simulations to shed more light on the issue.

Gravitational waves: A review on the future astronomy

Detection of Gravitational waves opened a new path for cosmological study in a new approach. From the detection of gravitational waves signal by advanced LIGO, its research climbed the peak. After the collaboration of LIGO and Virgo, several observations get collected from different sources of binary systems like black holes, binary neutron stars even both binary black hole and neutron star. The rigorous detection of gravitational signals may provide an additional thrust in the study of complex binary systems, dark matter, dark energy, Hubble constant, etc. In this review paper, we went through multiple research manuscripts to analyze gravitational wave signals. Here we have reviewed the history and current situation of gravitational waves detection, and we explained the concept and process of detection. Also, we go through different parts of a detector and their working. Then multiple gravitational wave signals are focused, originated from various sources and then found correlation between them. From this, the contribution of gravitational waves in different fields like complex binary systems (black holes, neutron stars), dark matter, dark energy and Hubble Constant have been discussed in this manuscript.

An Overview of Nano Multilayers as Model Systems for Developing Nanoscale Microstructures

The microstructural transformations of binary nanometallic multilayers (NMMs) to equiaxed nanostructured materials were explored by characterizing a variety of nanoscale multilayer films. Four material systems of multilayer films, Hf-Ti, Ta-Hf, W-Cr, and Mo-Au, were synthesized by magnetron sputtering, heat treated at 1000 °C, and subsequently characterized by transmission electron microscopy. Binary systems were selected based on thermodynamic models predicting stable nanograin formation with similar global compositions around 20–30 at.%. All NMMs maintained nanocrystalline grain sizes after evolution into an equiaxed structure, where the systems with highly mobile incoherent interfaces or higher energy interfaces showed a more significant increase in grain size. Furthermore, varying segregation behaviors were observed, including grain boundary (GB) segregation, precipitation, and intermetallic formation depending on the material system selected. The pathway to tailored microstructures was found to be governed by key mechanisms and factors as determined by a film’s initial characteristics, including global and local composition, interface energy, layer structure, and material selection. This work presents a global evaluation of NMM systems and demonstrates their utility as foundation materials to promote tailored nanomaterials.

Structure diagram and dynamics of formation of hexagonal boron nitride in phase-field crystal model

The phase-field crystal (PFC-model) is a powerful tool for modelling of the crystallization in colloidal and metallic systems. In the present work, the modified hyperbolic phase-field crystal model for binary systems is presented. This model takes into account slow and fast dynamics of moving interfaces for both concentration and relative atomic number density (which were taken as order parameters). The model also includes specific mobilities for each dynamical field and correlated noise terms. The dynamics of chemical segregation with origination of mixed pseudo-hexagonal binary phase (the so-called ‘triangle phase’) is used as a benchmark in two spatial dimensions for the developing model. Using the free energy functional and specific lattice vectors for hexagonal crystal, the structure diagram of co-existence of liquid and three-dimensional hexagonal phase for the binary PFC-model was carried out. Parameters of the crystal lattice correspond to the hexagonal boron nitride (BN) crystal, the values of which have been taken from the literature. The paper shows the qualitative agreement between the developed structure diagram of the PFC model and the previously known equilibrium diagram for BN constructed using thermodynamic functions. This article is part of the theme issue ‘Transport phenomena in complex systems (part 2)’.

Static absorber modelling

Introduction/purpose: A static absorber is capable of neutralizing any signal either in the physical or virtual domain and its analysis will be presented in this paper. Methods: The approach used here includes purely scientific thoughts as well as a model with its explanations evaluated step by step applying highly sophisticated computer tools for design and simulation. No empirical results will be attached, only claims with their evidence. Results: The crucial outcome of this research is a completely new approach to binary systems that are now observed as a set of real numbers. Conclusion: The purpose of this research is to introduce something brand-new that can be used in cyber industry while a dynamic variation of the absorber is still under development.