Synergetic effects of organic and inorganic additives on improvement in hydrophilicity and performance of PVDF antifouling ultrafiltration membrane for removal of natural organic material from water

Surrounding vegetation, animal, human and microbiological decomposition are the strong source of humic acid (HA) falling into the surface water bodies through rain runoff in the monsoon. HA contains various functional groups, such as carboxylic, phenolic, hydroxyl, and quinine, which are the major foulant. Contact of HA may have an adversarial health issue to human beings namely goiter, black foot, and cancer disease. The maximum permissible limit of HA in drinking water should be less than 2 ppm as per the Environmental Protection Agency (EPA). The membrane technology has prevailed a prominent place worldwide in chemical, water and wastewater treatment technologies. The proposed work is focused on the blending of organic-water soluble polymer polyethylene glycol 6000 as a pore-forming agent and inorganic salt lithium bromide (LiBr) as membrane morphology modifier with polyvinylidene fluoride host polymer in the N,N-Dimethylacetamide solvent. All fabricated membranes were characterized for functional groups and morphology. The total number of pores per unit surface area of membrane for membranes M-LiBr-0, M-LiBr-1, M-LiBr-2, and M-LiBr-3 are 2 × 10¹³, 2.3 × 10¹⁴, 2.7 × 10¹⁴ and 2.82 × 10¹⁴, respectively. The static water contact angle was decreased from 68.2° to 50.6° with an increase in the content of LiBr from 0 to 3 wt%. The order of pure water flux and hydraulic permeability of the membrane was M-LiBr-0 < M-LiBr-1 < M-LiBr-2 < M-LiBr-3. The HA rejection of the membrane was also increased from 90.13% to 96.24% with LiBr content due to a decrease in pore size of the membrane with the addition of LiBr content.     

Reversible Control of Gelatin Hydrogel Stiffness by Using DNA Crosslinkers**

Biomaterials with dynamically tunable properties are critical for a range of applications in regenerative medicine and basic biology. In this work, we show the reversible control of gelatin methacrylate (GelMA) hydrogel stiffness through the use of DNA crosslinkers. We replaced some of the inter-GelMA crosslinks with double-stranded DNA, allowing for their removal through toehold-mediated strand displacement. The crosslinks could be restored by adding fresh dsDNA with complementary handles to those on the hydrogel. The elastic modulus (G’) of the hydrogels could be tuned between 500 and 1000 Pa, reversibly, over two cycles without degradation of performance. By functionalizing the gels with a second DNA strand, it was possible to control the crosslink density and a model ligand in an orthogonal fashion with two different displacement strands. Our results demonstrate the potential for DNA to reversibly control both stiffness and ligand presentation in a protein-based hydrogel, and will be useful for teasing apart the spatiotemporal behavior of encapsulated cells.     

Structural,optical, cytotoxicity,and antimicrobial properties of MgO,ZnO and MgO/ZnO nanocomposite for biomedical applications

In this study, MgO nanoparticles were successfully fabricated and incubated inside ZnO NPs to form MgO/ZnO nanocomposite for biomedical applications. The x-ray diffraction analysis of MgO, ZnO, and MgO/ZnO has shown the single-phase x-ray diffraction patterns through X'pert High score. The crystallite sizes were calculated as 18 nm, 42 nm, and 53 nm, respectively. The average particle size of MgO, ZnO, and MgO/ZnO nanopowders depicted from secondary electron images of field emission electron microscopy were 56 nm, 400 nm, and 450 nm, respectively. The presence of MgO NPs inside ZnO NPs was confirmed by transmission electron microscopy. The elemental dispersive spectroscopy of MgO, given the peaks of oxygen and magnesium, also showed only zinc and oxygen peaks in ZnO, which confirms no other impurities in MgO and ZnO powders. The elemental analysis of MgO/ZnO nanocomposite showed the peaks of Zinc and Oxygen, along with a tiny peak of Mg. The photoluminescence and UV–vis spectroscopy revealed the absorbance fluorescence limit of the nanomaterials. Fourier transform infrared spectroscopy confirmed the several groups present in the nanocomposite. The biocompatibility of MgO, ZnO, and MgO/ZnO was observed with human peripheral blood mononuclear cells. The cytotoxicity studies were also performed against human cancer (liver and breast) cell lines. The MgO, ZnO, and MgO/ZnO exhibited the antimicrobial properties against Escherichia coli and Staphylococcus aureus.     

3D word spotting using leap motion sensor

Multimedia Tools and Applications - Leap motion sensor provides a new way of interaction with computers or mobile devices. With this sensor, users can write in air by moving palm or finger, thus,...     

Corrosion behavior of Monofrax K-3 refractory in borosilicate-based model low activity waste glass melts

Owing to its good chemical and thermal durabilities at high temperatures, Monofrax K-3 refractory is widely used in nuclear waste vitrification as a lining material in melting vessels. However, the corrosion of K-3 refractory during the vitrification of nuclear waste is a serious problem because it affects the melter's safety, performance, and lifetime. Therefore, in the present study, we have focused on unearthing the impact of glass network formers, such as SiO₂, B₂O₃, and Al₂O₃, in a model nuclear waste glass composition on the corrosion of Monofrax K-3 refractory. The corrosion tests have been performed per ASTM C621 at 1150°C for 5 days. The dimensional measurements on corroded K-3 refractory suggest that Al₂O₃ and SiO₂ tend to reduce the refractory corrosion (neck loss), with the effect of Al₂O₃ being significant. A corroded region on the K-3 refractory at the melt–refractory interface is observed. The corrosion occurs via a coupling of the melt infiltration induced by a capillary effect and the dissolution of Al, Mg, and Fe components from K-3 into the melt through chemical reactions. A Cr-rich layer is retained on the glass contact surface of the corroded K-3 refractory.     

Evaluation of compressive behaviour of porous structures under large deformation using micro-CT,DVC and micro-FE

Compressive behaviour of open and closed cell polyurethane foam samples under large deformation is studied using micro-Computed Tomography (micro-CT), Digital Volume Correlation (DVC) technique and micro-Finite Element (micro-FE) modelling. The micro-CT images of the foam samples at different compression strains are used to determine anisotropy in the foams, to obtain qualitative information on deformation mechanisms, to quantify the deformation and strains using a local DVC approach and to generate images for micro-FE modelling of the foam samples. Micro-FE modelling predicts the deformation using an elastoplastic material model coupled with continuum damage mechanics. Two different types of boundary conditions, experimentally derived (ExBC) and interpolated from DVC (IPBC), were implemented to evaluate the displacements in the micro-FE models. A reduced integration scheme in micro-FE analysis resulted in high artificial energy and was discarded in favour of full integration. The displacement predicted by IPBC matched with DVC displacement contours for closed cell foam. The ExBC-predicted axial displacement (W) showed a better agreement with DVC than transverse displacements (U, V) contours. However, a significant statistical comparison (R² > 0.70) of all displacements was obtained for both IPBC and ExBC. For open cell foam, both boundary conditions predicted a significant difference in the displacement contours with respect to DVC measurements. Still, the axial displacements of ExBC and IPBC showed a better statistical significance (R² > 0.70).     

Synergistic use of ultra-high-performance fiber-reinforced concrete (UHPFRC) and carbon fiber-reinforced polymer (CFRP) for improving the impact resistance of concrete-filled steel tubes

Concrete-filled steel tubes (CFSTs) have received growing attention, owing to their rapid construction, reduced labor requirement, and reasonable material cost. While in service, the CFSTs can be subjected to unexpected impact loads, originating from vehicle and vessel collision, as well as water- and wind-borne debris impact. Such extreme loading events often cause a partial or complete failure of conventional CFSTs, risking the safety and performance of the entire structural systems that rely on them. To address this issue, the current study explores how two advanced composite materials, including ultra-high-performance fiber-reinforced concrete (UHPFRC) and carbon fiber-reinforced polymer (CFRP), can be utilized to provide superior mechanical properties and minimize the vulnerability of CFSTs to impact loads. The composite materials under consideration are appropriate for both new and existing structures, in which normal-strength concrete can be replaced with UHPFRC, while CFRP sheets can further strengthen the CFSTs. For obtaining in-depth insights, a computational framework validated with the experimental tests was developed in the current study. Using a set of representative impact scenarios, various response measures, such as internal forces and deflections, as well as the energy absorbed by the CFSTs, were recorded during impact simulations. The investigations were then further extended to capture the influence of the main design parameters related to concrete, CFRP, and steel tube. From the conducted investigations, an energy absorption index was introduced, as a measure to evaluate the performance of CFSTs under impact loads.     

Rheology of nylon 6 containing metal halides

Addition of metal halides to nylons has been shown to be advantageous in a number of ways. The decrease in melting temperature, increase in glass transition temperature and melt viscosity by such additions have allowed more convenient processing of low molecular weight polymers and thermally unstable polymers. Rheological data depicting the variation of melt viscosity with shear rate at temperatures relevant to processing are necessary in optimizing and trouble-shooting plastics processing operations. In the present paper, a method has been proposed to estimate, complete flow curves or rheograms of nylon—metal halide systems with the use of a master curve knowing the melt flow index and glass transition temperature of the system. The validity of the approach has been verified for the nylon 6—lithium chloride system and shown to hold good for any nylon—metal halide combination.     

Temperature-dependent bending loss characteristics of W-type photonic crystal fibres: design and analysis

The temperature-dependent bending loss characteristics of two solid-core W-typephotonic crystal fibres have been reported by employing full-vectorial finite element method. The bending loss characteristics of W-type-I photonic crystal fibrestructure have been found better than that of the W-type-II photonic crystal fibre structure. The proposed photonic crystal fibrestructures show significant nonlinearity and hence can be used in telecommunication and nonlinear applications such as visible to near-infrared supercontinuum generation. Macro-bend insensitive nature of the proposed photonic crystal fibres makes them suitable candidates for fibre-to-the-home applications.     

A Parametric Study on the Inception and Evolution of Underground Coal Fires Based on a Lab-Scale Experimental Setup

Fire Technology - The tendency of self-ignition of coal is the root cause of underground coal fires (UCFs). A parametric study is carried out on a lab-scale experimental setup developed based on...