Calorimetric Analysis Research Articles

Waste-Energy Nexus: Cellulose Wood Chips Conjugated Metal Nanoparticles Based Phase Transformation for Improving Thermal Energy Storage Performance.

Highlighting waste as a wealth is the future sustainability of the world. Also, using solar energy stored during off-sun periods will overcome the energy crisis. The introduction of wood chip waste for thermal energy storage systems is a sustainable opportunity. Cellulose derived from wood chips was mixed with the environmentally benign magnetite to form a composite (WCM) and mixed with paraffin-based PCM. The composite was characterized through transmission electron microscopy, TEM analysis, scanning electron microscopy, SEM (augmented with dispersive X-ray analysis, EDX). Micrographs, Fourier transform infrared (FTIR), and X-ray diffraction (XRD), which confirmed that the composite material was prepared. Various system proportions of the composite (0.5, 1.0, 2.0, and 4.0%) are embedded in paraffin, and then the thermal system performance is compared. The experimental data revealed that the addition of 2.0 weight percent of composite material showed superior system performance. Also, differential scanning calorimeter (DSC) and TEM analyses of the paraffin-based WCM-composite materials are conducted. The system achieved a heat gain of 87 kJ/min in comparison to 7 kJ/min for 2.0% WCM-PCM and pristine PCM, respectively. Hence, WCM-PCM embedded with waste stream nanoparticles could be suggested as a potential candidate for heating applications.

Co-treatment of steel slag and oil shale waste in cemented paste backfill: Evaluation of fresh properties, microstructure, and heavy metals immobilization

The environmentally sustainable treatment of steel slag (SS) and oil shale waste (OSW) is a significant concern in the field of industrial development. The mining industry also faces challenges related to the high costs and carbon emissions associated with ordinary Portland cement (OPC), leading to environmental pollution. To address these challenges, this study aimed to develop a cost-effective and environmentally friendly binder for cemented paste backfill (CPB) by utilizing SS and calcined oil shale waste (COSW) as primary precursors. Extensive investigations were conducted to evaluate the properties of the CPB sample with varying COSW content, including rheological properties, mechanical strength, and microstructure. The binder sample was comprehensively characterized using isothermal calorimetric analysis, X-ray diffraction (XRD), thermogravimetry (TG), and scanning electron microscopy (SEM). Based on systematic experimentation, an optimal blend ratio for the binder was determined, consisting of 60 wt% SS, 15 wt% COSW, 15 wt% phosphogypsum (PG), and 10 wt% OPC. The exceptional performance of the binder was attributed to the substantial formation of precipitated ettringite (AFt), resulting in a more compact structure and improved mechanical strength. Additionally, a sequential extraction test revealed that the heavy metals in the CPB sample were mainly present in the residual fraction, demonstrating the effective immobilization of heavy metals by the binder.

A novel super high latent heat ternary eutectic salt for high temperature thermal energy storage

This work is concerned with a novel ternary eutectic salt based phase change material (PCM) for high temperature thermal energy storage applications. We designed the PCM formulation in a FactSage environment and demonstrated that the formulation had a very high latent heat. The microstructure, thermal physical properties, thermal stability and cycling service life of the eutectic salt were measured experimentally with various analytical methods including scanning electron microscopy (SEM), X-ray diffractometer analysis (XRD), simultaneous thermogravimetric analyzer (STA) technique, differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA). The results indicated that the eutectic salt had a melting point of 552.23 °C with a superhigh fusion enthalpy of 661.33 J/g. The change of melting point and latent heat of salt after 1500 cycles is 0.48% and 7.84%, respectively, showing excellent cycle stability.

Comprehensive analysis of 3D printed PA6.6 and fiber‐reinforced variants: Revealing mechanical properties and adhesive wear behavior

AbstractWhile 3‐dimensional (3D) printing technology is advancing rapidly, commonly used filament materials are struggling to meet growing expectations. Polyamide (PA) is a material with high potential to replace commonly used low‐performance filament materials, thanks to its cost‐effectiveness and optimal material properties compared to advanced engineering materials. To explore this potential, the thermal, thermomechanical, and mechanical properties (at different temperatures), as well as the wear characteristics, of PA, short carbon fiber reinforced‐PA (SCFR‐PA), and short glass fiber reinforced‐PA (SGFR‐PA) filaments were comparatively examined in this study. Differential scanning calorimeter analysis (DSC), Dynamic Mechanical Thermal Analysis (DMA), uniaxial tensile tests, and Shore D hardness tests were conducted on the 3D printed specimens. The yield strength decreased by 48% and 73%, respectively, for neat PA as compared to room temperature when tested at 40 °C and 60 °C, while for SCFR‐PA, it decreased by 40% and 60%, and for SGFR‐PA, it decreased by 33% and 48%, respectively. The findings obtained from wear tests conducted on both bottom and top surfaces have demonstrated that glass reinforcement yields better results than carbon reinforcement. The experimental findings have been compared with SEM images, revealing their consistency.Highlights This study focuses on the performance evaluation of 3D printed PA and its composites. The mechanical properties of the materials at different temperatures were compared. Adhesive wear behavior is not directly related to fiber type, wear surface or hardness. Morphological analysis was conducted to elucidate the influence of fiber type on mechanical properties and wear behavior.

Effects of mechanical recycling on the properties of glass fiber–reinforced polyamide 66 composites in automotive components

Abstract In this study, we aimed to reveal the effective reusability of waste generated during the injection molding process of polyamide 66 (PA66) reinforced with 30 wt% of short glass fiber (PA66-GF30) widely used in the automotive industry. PA66-GF30 was subjected to the three mechanical recycling cycles, including regranulation and reinjection molding steps, and the recycled materials obtained in each of these cycles were included at the ratios of 15, 20, 25, and 30 wt% to the virgin composite. Thermogravimetric analysis and differential scanning calorimeter analyses showed that the number of recycling cycles and recycled material content in the composite had no significant change in the thermal stability and crystallinity degree of the PA66-GF30. The average fiber length determined by optical microscope analysis shifted to lower values from 300–350 to 150–250 μm by increasing the number of recycling cycles and the recycled material content. The fact that the recycled material content in the composite exceeds 25 wt% and the recycling cycle is applied three times played a key role in changing the mechanical and melt flow behaviors of the composite. Tensile strength, elastic modulus, and impact energy slightly decreased while the elongation at break and melt flow index increased.

Circular Economy Insights on the Suitability of New Tri-Layer Compostable Packaging Films after Degradation in Storage Conditions.

The environmental degradation of the films used in packaging is a key factor in their commercial use. Industrial and academic research is aimed at obtaining materials that have degradation features that ensure their eco-sustainability but, at the same time, preserve their use properties during storage and distribution periods. This study analyzes the degradability behavior over time of commercial packaging that meets the requirements of the UNE 13432 standard and the prEN 17427 (2020) home composting certification requirements under standard storage conditions. The study attempts to provide insight into the durability of the films under standard storage conditions, verifying that this type of packaging has a useful life of more than 12 months and that after this storage period it still retains the usability properties for which it was conceived. The analyzed sample has been manufactured using a three-layer technology under some commercial formulations based on PBAT + STARCH + PLA and has been analyzed monthly for 12 consecutive months. The macroscopic monitoring of the degradation of the sample has been carried out through the evolution of the mechanical properties and the quantification of the color changes (very important in films) via colorimetry. The nature of the observed variations has been justified at the microstructural level from the data obtained in calorimetric analysis (DSC) and from the characterization using FTIR. The results indicate a loss of properties in the tensile, elongation and impact tests and a behavior of stability or improvement in the tear properties of the film. Analyzing the microstructural changes, it is observed that the degradation of a hydrolytic and thermo-oxidative type occurs in the amorphous part of the film. The conclusion of this study is that the proposed packaging, focused on domestic composting and stored under standard conditions, has a useful life of more than 12 months. This period should be sufficient to cover the stages of production, storage and final use.

Preparation of chondroitin sulfate and polyvinyl alcohol hydrogels as drug carriers

The chondroitin sulfate/polyvinyl alcohol based pH-sensitive hydrogels (CHS/PVA hydrogels) were synthesized by a free radical polymerization technique for controlled delivery of diclofenac sodium up to 72 h. Polymers chondroitin sulfate and polyvinyl alcohol were crosslinked with monomer acrylic acid by a cross-linker ethylene glycol dimethylacrylate in the presence of initiator ammonium persulfate. The process of polymerization was continued for 24 h at 65 °C. Fourier transform infrared spectroscopy (FTIR) indicated successful polymerization and crosslinking among the hydrogel contents. Differential scanning calorimetric (DSC) and thermogravimetric analysis (TGA) studies demonstrated that fabricated hydrogel has higher thermal stability. The pH sensitivity of designed CHS/PVA hydrogel was investigated by performing dynamic swelling and in vitro drug release tests in pH 1.2, 4.6, and 7.4 medium. Maximum swelling was observed at pH 7.4 when compared to pH 1.2 and 4.6. The sequence of drug release from the developed hydrogel was; pH 7.4 > 4.6 > 1.2. It has been shown that porosity, swelling, and release rate of diclofenac increased with the addition of chondroitin sulfate and acrylic acid, while decreased with increasing PVA composition. Cytotoxicity studies showed that the prepared hydrogel has no toxic effect on T84. Therefore, it can be demonstrated from the results that the CHS/PVA cross-linked hydrogel can be considered as a potential delivery carrier for the controlled release of diclofenac sodium.

Detachable-dissolvable-microneedle as a potent subunit vaccine delivery device that requires no cold-chain

Although vaccine administration by microneedles has been demonstrated, delivery reliability issues have prevented their implementation. Through anex vivoporcine skin experiment, we show visual evidence indicating that detachable dissolvable microneedles (DDMN) can deposit cargo into the dermis with insignificant loss of cargo to the stratum corneum. Using ovalbumin (OVA), a model antigen vaccine, as a cargo, theex vivoexperiments yielded a delivery efficiency of 86.08 ± 4.16 %. At room temperature, OVA could be stabilized for up to 35 days in DDMN made from hyaluronic acid and trehalose. The DDMN matrix could improve the denaturation temperature of the OVA from around 70–120 °C to over 150 °C, as demonstrated by differential scanning calorimetric analysis. In vivodelivery of OVA antigen into the mice's skin via DDMN elicited 10 times higher specific antibody responses compared to conventional intramuscular injection. We envision DDMN as an effective, precise dosing, intradermal vaccine delivery system that may require no cold-chain, offers a dose-sparing effect, and can be administered easily.

Green synthesized 3D coconut shell biochar/polyethylene glycol composite as thermal energy storage material

Developing stable, economic, safer and carbon-based nanoparticles from agro solid waste facilitates a new dimension of advancement for eco-friendly nanomaterials in competition to existing nanoparticles. Herewith, a three dimensional highly porous honeycomb structured carbon-based coconut shell (CS) nanoparticle is prepared through green synthesis technique using tube furnace to energies organic phase change material (PCM). CS nanoparticle synthesis using a green approach is incorporated with polyethylene glycol (PEG) using a two-step technique to develop PEG/CS nanocomposite PCM. Thermophysical features of the nanocomposites are characterized using transient hot bridge (ThB), differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA), whereas optical property and chemical stability is evaluated using UV–Vis and FTIR spectrometers. Resulting nanocomposite demonstrates higher thermal conductivity by 114.5 % (improved from 0.24 W/m⋅K to 0.515 W/m⋅K). Energy storage enthalpy increased from 141.2 J/g to 150.1 J/g with 1.0 % weight fraction of CS nanoparticles. Optical absorbance of the nanocomposite is improved by 2.14 times compared to base PCM. The developed nanocomposite samples exhibit extreme thermal stability up to 215 °C. The 3D porous structure of CS nanoparticles shows better contact area with PEG, causing low interfacial thermal resistance for improved thermal network channels and pathways for extra heat transfer and phonon propagation.

Developing Wallpaper/Dodecyl alcohol composite phase change materials as new kind of wall covering elements for building interior thermoregulation

This study introduces a novel wall-covering element consisting of wallpapers (WP) impregnated with Phase Change Material (PCM), with the aim of enhancing thermal properties and providing effective thermal regulation performance in interior spaces. The study conducts practical investigations into the thermal attributes of wallpapers (WPs) impregnated with Dodecyl alcohol (DDA) as the chosen PCM, culminating in a leakage-free WP/DDA wall covering element. The process of impregnating involved applying liquid DDA to the back side of the WP using a manual coating apparatus. Four distinct DDA ratios, ranging from 0% to 20% by mass of WP, were applied. The chemical compatibility of the developed WP/DDA composite was explored using Fourier Infrared Spectroscopy (FTIR). The thermal energy storage (TES) properties were assessed through Differential Scanning Calorimeter (DSC) analysis, and the thermo-regulative performance of the WP/DDA composite was evaluated in laboratory-scale test rooms under real weather conditions. The DSCoutcomesexposed that melting temperature and latent heat capacity of WP/DDA were 21.78 °C and 26.9 J/g, respectively.The thermoregulation tests showed that the prepared WP/DDAsignificantly reduce interior room temperature fluctuation and can maintain indoor temperature longer in comfortable temperature ranges. The largest difference between the reference room and test room was observed to be about 2℃. The room temperature was cooler for about 9 h 53 min during day times for the DDA case.The results designated that the developed WP/DDA composite could be evaluated as a promising new kind of building wall covering element for reducing the cooling load of room.

Effect of different activation techniques on the engineering properties of cement-free binder containing volcanic ash and calcium carbide residue

This study developed a cement-free binder using volcanic ash (VA) and calcium carbide residue (CCR) as an alternative binder to cement. First, the optimal proportions of VA and CCR were determined to achieve superior flow, compressive strength, and bulk electrical resistivity. After that, various activation techniques, namely physical (sieving the CCR on sieve No. 325), chemical (adding 1 % NaOH by binder mass to the paste), and thermal (curing the paste in an oven at 65℃ for 24 h), were used either exclusively or synergically to enhance the performance. The results show that the optimum VA:CCR was 95:5. The flow increased by chemical activation but decreased with physical activation. Using subsequent physical and chemical activation led to a slight increase in flow. Binders subjected to physical activation followed by thermal activation had the highest compressive strength of 31.2 MPa at 28 days of curing. In contrast, subsequent combined chemical and thermal activation produced superior bulk resistivity of 193 Ω.m at the same age compared to other activation techniques. Nevertheless, all activation techniques improved the strength and bulk resistivity. The calorimetric analysis confirmed that the emitted heat increased with different activation methods compared to the mix without activation, which agreed with compressive strength results. X-ray diffraction (XRD) analysis showed that the reaction products were calcium-silicate-hydrate and calcium-aluminate-silicate-hydrate gels. Scanning electron microscope (SEM) images confirmed that different activation techniques resulted in a denser microstructure than the inactivated VA-CCR paste. This cement-free binder contributes to the ongoing efforts to reduce the carbon footprint of cement-based materials by finding sustainable alternative binders to cement.

Thermo-optic response and mechanical properties of hybrid polyurethane elastomers via silicon group-induced microphase separation evolution

In this study, silicon hybrid polyurethane elastomers (SPUs) with flower-like microstructure were constructed by a two-step method according to incorporating diphenylsilanediol (DPSD) into hard segments. The reinforced microphase separation of SPUs was estimated by combining Fourier transform infrared spectrometer (FT-IR) characterization with differential scanning calorimeter (DSC) and dynamic mechanical analyzer (DMA). The silicon heteroatom-inducing flower-withering like morphology for SPUs was found with increasing silicon groups, which revealed an evolution from flowers-blossoming to broken petals like microdomain due to the ordered aggregation of hard segments. In addition, the reversible thermo-optic response of SPUs, a sharp transition from light opaque at room temperature to more than 55% transmission at 160 °C, was observed, attributing to “sea-island” or bi-continuous structural evolution owing to hydrogen bond dissociation or recombination with changing the temperature. Comparing with pure PU, the enhanced mechanical properties of SPUs were achieved, more than 20 times tensile strength (14.75 ± 2.52 MPa) and more than 3 times elongation at break (293.31 ± 2.87%). In sum, the study was of great significance for designing novel functional segmented PU materials.

A sustainable approach to managing city park waste through biochar as a renewable energy source

An abundant natural resource known as lignocellulosic biomass is seen to be a promising and sustainable alternative to renewable energy. A carbon-rich, porous substance called biochar is created when biomass is thermally decomposed during pyrolysis procedures in order to make biofuels. Biochar can be made in big industrial facilities or on a local scale. In order to limit the usage of fossil fuels and find a solution for managing urban park garbage, this project will examine the potential of biochar made from waste from city parks as a renewable energy source. A 25-gram natural zeolite catalyst was used to produce biochar at temperatures between 100 and 500 °C with sample weights of 50, 100, 150, and 200 grams. Calorimetric analysis, FTIR analysis, SEM analysis, XRF analysis, ultimate analysis, and proximate analysis are used to characterize the product. The results showed that the zeolite process produced the maximum calorific value of biochar at 6009.8 cal/gram, the highest yield of biochar at 200 °C, and the weight of 50 grams of biomass without a catalyst at 96%. Aliphatic OH and CH groups associated with phenols, alcohols, and carboxylic acids can be seen using FTIR analysis. Large holes can be seen in leaf litter biochar according to SEM examination. For biochar products, the XRF examination of the metal elements Al, Si, P, S, Cl, K, Ca, Ti, Mn, Fe, Co, Zn, Rb, Sr, Na, Mg, Sr, and Pb is within the permitted limits. Leaf waste can be converted into a non-toxic renewable energy source because biochar has a low sulfur concentration of 4.0%. The findings of this study are anticipated to fill in some gaps left by earlier studies, particularly with regard to the use of garbage from municipal parks and the advancement of renewable energy sources..

Thermal stability of natural fiber reinforced biodegradable composites

Polymer composites reinforced with natural fibers are being increasingly developed by researcher and scientist in the recent field of material science due to their various applications in aerospace, marine and industries. The hydrophilic natural fibers are incompatible with the hydrophobic polymer matrices this leads to less interfacial bonding between fibers and matrix. In this paper, fibers were collected from desert plant prosopis juliflora and NaOH treatment was done to increase interfacial bonding of fiber-Matrix. Prosopis Juliflora fiber reinforced phenol formaldehyde composites were prepared with different fiber loading up to 20wt% and then characterized by thermo gravimetric analysis. This paper describes thermal properties composites materials by Thermo gravimetric analysis TGA and Differential scanning calorimetric DSC analysis of composite materials with different heating rates and hence establishes a connection between temperature and physical properties of substances. This study highlights the potential of alkali treatment in improving the thermal stability of the composites. This paper concludes that by, increasing the fiber weight percentage (fiber loading) in PF resin does increase the thermal stability of the resulting composite. The mass residue of untreated fiber reinforced PF composites with fiber loading 15% wt. UTFRPFC 15was 35%, while treated fiber reinforced PF composites with fiber loading 15% wt. ATFRPFC 15 had a mass residue of 75% at a temperature of 400°C. This clearly shows that alkali treatment significantly enhances the thermal stability of the composites. Alkali pre-treatment activates the fibers’ surface and helps increase the fiber’s mechanical strength.

Cholesterol based mesogenic Schiff’s base derivatives with carbonate linkage: Synthesis, characterisation and photoluminescence study

ABSTRACT The steroidal derivatives have been found to be extremely good mesogens since their origin. Due to their inherent chirality, they have the potential to induce a wide variety of liquid crystalline phases, including frustrated phases, depending on the structure of the steroidal skeleton and the substituents attached. In this report, thirteen new homologous Schiff’s base derivatives were synthesised by condensing 4-n-alkoxy aniline with 4-formyl phenyl cholesteryl carbonate. All the compounds were characterised using elemental analysis, FT-IR, 1H-NMR and 13C-NMR. In order to study the liquid crystalline behaviour of the synthesised compounds, optical texture studies were carried out using polarising optical microscope in heating and cooling cycles. The derivatives showed a variety of mesophases, including chiral nematic (N*), twist grain boundary-A (TGBA), smectic A (SmA) and chiral smectic C (SmC*) phases. The thermal behaviour was determined using a differential scanning calorimeter and thermogravimetric analysis. All the synthesised compounds are UV-active and show photoluminescence in the blue emission region with good quantum yield.

Study on preparation, characterization and application of mixed-colorants thermochromic microcapsules

In order to expand the color-change range and make the discoloration temperature suitable for the daily textiles, a new formulation of mixed-colorants thermochromic core material is designed, in which crystal violet lactone (CVL) is the basic color former, bisphenol A (BPA) is the developer, especially the solvent-based dye and dodecyl dedecanoate are used as the extended dye and the solvent, respectively. Scanning electron microscope (SEM), differential scanning calorimeter (DSC) and thermogravimetric analyzer (TGA) were applied to study the morphology, encapsulation rate, non-isothermal crystallization behavior and thermal stability of the mixed-colorant thermochromic microcapsules (MCTMs) prepared by in-situ polymerization. The results show that MCTMs have good sphericity, uniform particle size, good thermal stability and the encapsulation rate can reach 86.73%. Under the non-isothermal conditions, the encapsulation of formaldehyde-melamine resin wall material can slightly reduce the crystallization rate of the solvent, but does not affect the relative crystallinity, thermal properties and discoloration sensitivity of the core materials. With the variety of ambient temperatures in the range of 20–35 °C, the printed cotton fabrics with MCTMs could change color reversibly between different tones with good reliability and durability, and exhibit more gorgeous colors than the common thermochromic materials.

An Experimental Study for Deriving Fire Risk Evaluation Factors for Cables in Utility Tunnels

In this study, we performed three tests to measure the fire-retardant performance of power cables installed in utility tunnels. The standards we applied for testing are ISO 5660-1, NES 713, and IEEE 1202. Specifically, we performed a cone calorimetric analysis, calculated the toxicity index, and measured the flame spread length on material surfaces. Even though the same fire-retardant chemical composites were applied, various differences in fire-retardant performance were found depending on the chemical properties of the cable sheath and insulation. We also found that gaseous substances generated during the burning of cables can serve as important risk assessment factors in fires. We determined that, in addition to the heat generated when the cable burns, the toxic gases emitted at this time can also be a risk factor. This is because it is important to consider any potential risk to a person entering as part of an initial response to an event or accident involving cables installed in utility tunnels. Moreover, in the event of a fire in the cable, there is a risk of hazardous substances flowing into the city center as toxic gases are released. Therefore, we determined that the risk of hazardous gases emitted during cable fire should be reflected in the fire-retardant performance standard.

Topology Optimization of Prelithiated Sio for Improving Dimensional Stability

As the demand for high energy density materials of lithium ion batteries increases, silicon monoxide is considered one of the promising anode materials that can replace the conventional anode materials. However, the low initial Coulombic efficiency(ICE) and the poor cycle stability bottlenecks the commercialization of SiO material. Although numerous efforts have been made, these two chronic issues of SiO have not been solved simultaneously. Here, we demonstrated a prelithiation method to improve the ICE as well as cycle ability by optimizing the topology of prelithiated SiO. Calorimetric method and LA-APT analysis revealed that four exothermic reactions are related with the topology and microstructure of prelithiated SiO. At the optimum heat treatment temperature of 650 ℃, the prelithiated SiO showed a capacity of 1164 mAh g-1 with an ICE of 89.6 % and a remarkable capacity retention of 73.4 % at 300 cycles. We also found that the optimized electrode expanded less compared to non-optimized prelithiated SiO materials. The outstanding electrochemical properties were attributed to the modulated topological arrangement of the active Si phase and Li2SiO3 inactive buffer phase. Further description of the topological optimization will be discussed in the presentation.

Water content significantly influences post-cryopreservation survival of air-desiccated oil palm (Elaeis guineensis Jacq.) zygotic embryos: A thermal and ultrastructural study

The present study outlines the influence of free water content in oil palm (Elaeis guineensis Jacq.) zygotic embryos after desiccation on survival post-cryopreservation. Aseptically isolated zygotic embryos were analysed for water content and resurgence ability after air-desiccation and freezing (in liquid nitrogen). The results indicated that the desiccated zygotic embryos with water content of below 0.24 and above 0.16 g H2O /g dry weight (dw) exhibited survival after freezing. The survival was maximum (80%) when the desiccated zygotic embryos contained 0.16 g H2O /g dw of water content. This optimal water content not only helped oil palm zygotic embryos to sustain their cellular integrity but also assisted to retain their regeneration potential following cryopreservation. On the contrary, the zygotic embryos with water content above 0.24 g H2O /g dw or below 0.16 g H2O /g dw lost their viability as well as their cellular integrity attributable to either excess water content or excessive loss of water, after desiccation and successive freezing. Differential scanning calorimetric analysis revealed characteristic sharp peak for zygotic embryos with high water content and reduced peaks with successively lower water content. Scanning electron microscopic and transmission electron micrographic studies also confirmed that there was no noteworthy distinction in morphology of epidermal layer and cellular integrity between zygotic embryos with different water content before and after desiccation as well as their successive freezing. The parallel trend was reflected in their revival also.

Multi-spectroscopic, calorimetric and molecular dynamics evaluation on non-classical intercalation of antiviral drug Molnupiravir with DNA

The interaction of an antiviral drug Molnupiravir (MOL) with calf thymus DNA (CT-DNA) was investigated using a series of biophysical techniques. A significant hyperchromism with a blue shift nm in the UV-Vis spectra indicated a high binding affinity of MOL for CT-DNA with binding constants in the order of 105 M−1. Competitive fluorescent dye displacement assays with ethidium bromide (EB) and Hoechst 33258 suggested an intercalative mode of binding of MOL with CT-DNA. Thermodynamic profiles determined using fluorescence titration and isothermal titration calorimetric (ITC) analysis matched well with each other. The negative free energy change revealed that the MOL/CT-DNA complexation is a spontaneous process. The negative values of enthalpy and entropy changes indicated that H-bonding and van der Walls interactions play dominant roles in stabilizing the complex. A decrease in viscosity of CT-DNA solution upon adding MOL indicated a partial intercalation mode of binding which was well supported by circular dichroism (CD) spectral and effect of KI and denaturation studies. Molecular docking and metadynamics simulation studies clearly showed the partial intercalation of the pyrimidine ring of MOL into the base pairs of DNA. Free energy surface (FES) contour indicated that the drug/DNA complex is stabilized by H-bonding and pi-pi/pi-cation interactions. Communicated by Ramaswamy H. Sarma