Tolerance limit of chloride for steel in blended cement mortar using the cyclic polarisation technique

The tolerance limit for chloride in ordinary Portland cement (OPC) and blended cements such as Portland pozzolana cement (PPC) and Portland slag cement (PSC) was assessed by cyclic polarisation. This study covers both cement extracts and mortar. The salient features of this investigation were: in extracts, the tolerance limit for chloride actually doubles for PSC when compared to PPC and OPC. The tolerance limit for chloride for various mortars follows the order: PSC > PPC > OPC. In OPC and PPC mortar, the repassivation potential (E _rep) shifted negatively with higher amounts of free chloride but in PSC mortar E _rep shifted positively (+590 mV) even in the presence of 5,000 ppm of free chloride. PSC takes longer time (50 days) to reach E _rep indicating perfect passivity maintained for the embedded steel.     

Increased LRG1 Levels in Overweight and Obese Adolescents and Its Association with Obesity Markers,Including Leptin,Chemerin, and High Sensitivity C-Reactive Protein

Leucine-rich α-2 glycoprotein1 (LRG1) is a member of the leucine-rich repeat (LRR) family that is implicated in multiple diseases, including cancer, aging, and heart failure, as well as diabetes and obesity. LRG1 plays a key role in diet-induced hepatosteatosis and insulin resistance by mediating the crosstalk between adipocytes and hepatocytes. LRG1 also promotes hepatosteatosis by upregulating de novo lipogenesis in the liver and suppressing fatty acid β-oxidation. In this study, we investigated the association of LRG1 with obesity markers, including leptin and other adipokines in adolescents (11–14 years; n = 425). BMI-for-age classification based on WHO growth charts was used to define obesity. Plasma LRG1 was measured by ELISA, while other markers were measured by multiplexing assay. Median (IQR) of LRG1 levels was higher in obese (30 (25, 38) µg/mL) and overweight (30 (24, 39) µg/mL) adolescents, compared to normal-weight participants (27 (22, 35) µg/mL). The highest tertile of LRG1 had an OR [95% CI] of 2.55 [1.44, 4.53] for obesity. LRG1 was positively correlated to plasma levels of high sensitivity c-reactive protein (HsCRP) (ρ = 0.2), leptin (ρ = 0.2), and chemerin (ρ = 0.24) with p < 0.001. Additionally, it was positively associated with plasma level of IL6 (ρ = 0.17) and IL10 (ρ = 0.14) but not TNF-α. In conclusion, LRG1 levels are increased in obese adolescents and are associated with increased levels of adipogenic markers. These results suggest the usefulness of LRG1 as an early biomarker for obesity and its related pathologies in adolescents.     

Competitive role of inhibitive and aggressive ions in the corrosion of steel in concrete

The effect of various inhibitive ions (hydroxide, citrate, stannate) for the corrosion of steel in concrete was studied by weight loss measurements, chronopotential studies, anodic polarization technique and compressive strength tests. The salient features of the investigation were: in 100% OPC as well as in OPC + fly ash (3:1 ratio) extracts the passivity of steel was readily destroyed even by the presence of 10 000 ppm of chloride. However in 100% OPC and also in OPC + fly ash (3:1 ratio) extracts containing inhibitive and complexing agents like hydroxide, citrate and stannate, the passivity of steel was maintained even in the presence of 30 000 ppm of chloride. The addition of inhibitive ions like hydroxide, citrate and stannate not only decreased the corrosion rate of steel in simulated concrete environments but also increased the compressive strength of mortars. Citrates, stannates and CaO are effective inhibitors of the corrosion of steel in concrete.     

The triangular potential sweep voltammetric studies on pure tin in concentrated sodium hydroxide solutions

The triangular potential sweep voltammetric studies were carried out on pure tin (99.9999%) in NaOH solutions (1–10 N). The forward scan revealed two distinguished peaks in the region ?1.12 to ?0.9 V vs sce and at faster sweep rates a single peak appeared. Oscillations were observed in the E-i curve in the potential regions of Sn/Sn(OH)₂ or Sn(OH)₂/Sn(OH)₄ in the forward scan; and increase of stannite concentration increased the oscillations. The non-stoichiometric nature of the passive oxide film is responsible for these oscillations. The first anodic peak potential and current dependencies on sweep rates revealed that a “pore resistance model” holds good. The appearance of a single cathodic peak at far negative potentials, compared to the anodic peak observed at higher sweep rate, was understood to be due to irreversible reduction of oxidised species formed on the forward scan. The fractional dependence of cathodic peak current and potential on stannite ion concentration, at constant OH^? ion concentration and a Tafel slope of 60 mV decade^?1, suggests the reduction of stannite involves activated adsorption of Sn(OH) obeying the Temkin isotherm with its discharge as a rate-determining step.     

Synthesis,characterization and corrosion evaluation on new cationomeric polyurethane water dispersions and their polyaniline composites

New aqueous cationomeric polyurethane dispersions (PUDs) were synthesized by three step reaction process. Isophorone diisocyanate (IPDI) was reacted with polyols, namely, polypropylene glycol-400, polypropylene glycol-1000 and polypropylene glycol-2000, to form prepolymers which were chain extended by reacting it with N-methyldiethanolamine (N-MDEA). Quarternization and self-emulsification with deionized water resulted in PUDs. The resultant cationomers were film casted and characterized by FT-IR, DSC, TGA, DMTA and SEM analyses. Further, for the first time in the literature, aqueous cationomeric polyurethane dispersions (PUDs) were used for blending with 2 wt%, 4 wt% and 6 wt% of polyaniline–DBSA water dispersions to form new conductive composites. The conductivity attained is in the range 1.2 × 10⁻⁵–3.7 × 10⁻⁵ S/cm. These composites were evaluated for their corrosion protection abilities on mild steel panels by standard accelerated tests.     

Synthesis and characterization of nano-encapsulated catechin by molecular inclusion with beta-cyclodextrin

Nano-encapsulation of catechin (CAT) with beta-cyclodextrin (BCD) at 1:1 ratio resulted in the production of nano-encapsulated powder (BCD + CAT) by molecular inclusion method. The interactions between CAT and BCD were analyzed by differential scanning calorimeter (DSC), Raman laser spectroscopy (RLS), scanning electron microscopy (SEM) and X-ray diffractometer (XRD). The results obtained strongly confirmed supra molecular complex formation. DSC thermograph obtained for nano-encapsulated powder resulted in the appearance of new endothermic melting peak at 250 °C with complete disappearance of peaks at 100, 150 and 200 °C present in catechin and beta-cyclodextrin indicating the inclusion complex formation which was also confirmed by spectral characterization (RLS). Particles ranging from 67 to 470 nm were obtained by SEM micrographs. Structural characterization by XRD at 2θ angle from 0° to 80° for nano-encapsulated powder indicated change of state from crystalline to amorphous phase with average particle size of 518.78 nm.     

Antibacterial activity of dithiothreitol reduced graphene oxide

A green and simple approach is described for the large scale synthesis of reduced graphene oxide (rGO). The transition of graphene oxide (GO) into graphene was confirmed using various analytical techniques. Raman spectroscopy data indicate the partial removal of oxygen-containing functional groups from the surface of GO and formation of graphene. X-ray diffraction (XRD) was used to investigate the crystallinity of graphene nanosheets. The antibacterial activity of GO and rGO was evaluated using cell viability, reactive oxygen species (ROS) production and DNA fragmentation assays. The results suggest that GO and rGO possessed an excellent antimicrobial activity against Escherichia coli.     

Electronic and optical modeling of solar cell compound CuXY<Subscript>2</Subscript> (X = In,Ga, Al; Y = S,Se, Te): first-principles study via Tran–Blaha-modified Becke–Johnson exchange potential approach

The electronic and optical properties of the ternary CuXY₂ (X = In, Ga, Al; Y = S, Se, Te) compounds have been investigated using the density functional theory based on the full potential linear augmented plane wave method via Tran–Blaha-modified Becke–Johnson exchange potential techniques. From this study, it is found that these compounds are direct band gap semiconductor and in good agreement with reported results. The optical properties such as dielectric tensor components and the absorption coefficient of these materials are determined in order to investigate their usefulness as solar cell materials.     

Antifungal Effect of Nanoparticles against COVID-19 Linked Black Fungus: A Perspective on Biomedical Applications

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a highly transmissible and pathogenic coronavirus that has caused a ‘coronavirus disease 2019’ (COVID-19) pandemic in multiple waves, which threatens human health and public safety. During this pandemic, some patients with COVID-19 acquired secondary infections, such as mucormycosis, also known as black fungus disease. Mucormycosis is a serious, acute, and deadly fungal infection caused by Mucorales-related fungal species, and it spreads rapidly. Hence, prompt diagnosis and treatment are necessary to avoid high mortality and morbidity rates. Major risk factors for this disease include uncontrolled diabetes mellitus and immunosuppression that can also facilitate increases in mucormycosis infections. The extensive use of steroids to prevent the worsening of COVID-19 can lead to black fungus infection. Generally, antifungal agents dedicated to medical applications must be biocompatible, non-toxic, easily soluble, efficient, and hypoallergenic. They should also provide long-term protection against fungal growth. COVID-19-related black fungus infection causes a severe increase in fatalities. Therefore, there is a strong need for the development of novel and efficient antimicrobial agents. Recently, nanoparticle-containing products available in the market have been used as antimicrobial agents to prevent bacterial growth, but little is known about their efficacy with respect to preventing fungal growth, especially black fungus. The present review focuses on the effect of various types of metal nanoparticles, specifically those containing silver, zinc oxide, gold, copper, titanium, magnetic, iron, and carbon, on the growth of various types of fungi. We particularly focused on how these nanoparticles can impact the growth of black fungus. We also discussed black fungus co-infection in the context of the global COVID-19 outbreak, and management and guidelines to help control COVID-19-associated black fungus infection. Finally, this review aimed to elucidate the relationship between COVID-19 and mucormycosis.