Free Energy Change Research Articles

Identification of phytocompounds as potent inhibitors of sodium/glucose cotransporter-2 leading to diabetes treatment

Type-II diabetes, a major metabolic disorder has threatened the very existence of a healthy life since long ago. Commercially available antidiabetic drugs are known for several adverse effects. The present study attempted to identify potential phytocompounds as inhibitors of sodium/glucose cotransporter-2 (SGLT2), a major protein that helps in glucose re-absorption from renal tubules. A total of 28 phytocompounds were collected based on the literature survey. 3D co-ordinates of phytocompounds were collected from PubChem database. Molecular docking was carried out with SGLT2 protein and the best 3 docking complexes were subjected to molecular dynamics simulation for 100 ns. Free energy changes were also analyzed using MM/PBSA analysis. Phytocompounds were also analyzed for their drug-likeness and ADMET properties. Docking study observed a strong binding affinity of phytocompounds (> −7.0 kcal/mol). More than 10 phytocompounds showed better binding affinity compared to reference drugs. Further analysis of three best docking complexes when analyzed by MD simulation showed better stability and compactness of the complexes compared to reference drug, empagliflozin. MM/PBSA analysis also revealed that van der Waals force and electrostatic energy are the major binding energy involved in the complex formation. Like docking energy, free energy analysis also observed stronger binding energies (ΔGGAS) in SGLT2-phytocompound complexes compared to empagliflozin complex. All the phytocompounds showed drug-likeness and considerable ADMET properties. The study, therefore, suggests that Trifolirhizin-6′-monoacetate, Aspalathin, and Quercetin-3-glucoside could be a possible inhibitor of SGLT2 protein. However, further studies need to be carried out to reveal the exact mode of activity. Communicated by Ramaswamy H. Sarma

Removal of Crystal Violet Dye in Textile Wastewater Using Rice Husk Biochar


 
 
 Crystal Violet Dye (CVD) is a water-soluble, hazardous organic dye that causes adverse health issues and environmental pollution. This dye was mostly added to wastewater by the textile industries. Treatment of CVD-contained wastewater has become a great challenge due to high investment and operating costs and inefficiency in dye removal of conventional methods such as biological degradation and chemical oxidation. So, the main purpose of this study is to investigate the CVD removal ability of Rice Husk Biochar (RHB). The experiment procedure was designed to determine the influence of initial CVD concentration, adsorbent dosage, pH, contact time, and temperature on dye removal. RHB was prepared by pyrolysis process at 700o C for 3h at a constant heating rate of 10o C min-1 in a muffle furnace. Adsorption of CVD by RHB was verified by performing Fourier Transform Infrared spectroscopy. The concentration of the remaining dye after adsorption studies was calculated using Ultra-Violet visible spectroscopy. According to the results, the dye removal efficiency increased with the RHB amount, but the rate of this increment decreased at higher RHB dosages. The highest dye removal efficiency of 97.33% was recorded at 1.5 g RHB amount. In the effect of initial CVD concentration, the efficiency increased up to 600 mg/l and then decreased and the maximum removal efficiency was 96.77%. pH value has no significant effect on dye removal and the highest efficiency of 97.3 % was recorded at pH 4. Further, as the contact time increased, the dye removal increased until it reached an equilibrium state at 60 minutes with 92.03% efficiency. Moreover, when raising the temperature, the adsorption of CVD by RHB marginally increased. According to the kinetic studies, the experimental data followed pseudo- second-order kinetic models than pseudo-first order. Further, adsorption equilibrium data well fitted both Freundlich and Langmuir isotherm models so that it can be assumed that both monolayer and multilayer adsorption of CVD in RHB surface. Thermodynamic parameters such as Gibbs free energy and enthalpy change were calculated, and all values were recorded as negative implying adsorption was favorable and spontaneous and the process was exothermic. In conclusion, the optimum dye removal was recorded at 350 C and pH 4 with an initial dye concentration of 600 mg/L and adsorbent dosage of 1.5 g. Thus, this study concluded that RHB could be utilized as a cost- effective, eco-friendly, and affordable adsorbent for the removal of CVD from wastewater with over 90% dye removal efficiency.
 Keywords: Crystal violet dye, Rice husk biochar, Textile industry, Adsorption
 
 

Degradation of Tolonium Chloride Dye by Phosphate Ion in Aqueous Acidic Solution: Kinetic Approach

The degradation of tolonium chloride (TC+) dye by phosphate ion (PO43-) in an aqueous acidic solution was studied using spectrophotometric analysis at 301 K, I= 1.0 M, [TC+]= 1.5 × 10-5 M, [H+]= 1.0×10-3 M, and ʎmax 600 nm. To determine the potency and rate of the reactant species, an aqueous acidic medium was employed. The reaction's direction and tendency were predicted using a thermodynamic analysis at an interval of 5.0 K and a temperature range of 301-321 K. Without the presence of intermediate complex/free atoms formation, a reaction that produced phenyl sulphoxide, phenylamine, and HPO32- as products of the reaction was obtained with a molar ratio of 1:1 for both reactants. First-order tolonium chloride reactivity was found in the reaction and first-order for the phosphate ion, resulting in a second-order reaction overall. The reaction process accelerated as the concentration of hydrochloric acid rose. The response time decreased with an increase in ionic strength concentration and added Ca2+ and Cl- did catalyze the reaction positively. A straight line that went through the origin was produced by plotting 1/ko vs PO43- concentration. The spectroscopic analysis showed no discernible shift from λmax of 600 nm. Additionally, an increase in temperature accelerated the reaction process. The reaction has a negative free energy change, G (-3.13–1.12 KJ/mol) which indicates that it is spontaneous and that the reactants have more free energy than that of the products. While the enthalpy of activation, H is positive and indicates that the reaction was endothermic and followed an associative path, the entropy of activation, S, is also negative (-7.45–1.10 KJ/mol), indicating that the reaction is less disordered. Due to the added ions catalysis and absence of free atoms during the course of the reaction, an outer-sphere mechanism was suggested for the reaction.

Exploring binding affinity of 1-n-Alkyl-3-methylimidazolium chloride with iron porphyrin and electron uptake ability of the ionic liquid-FeP complex

Interaction of ionic liquids with iron porphyrin (FeP) arises in a number of application of ionic liquids such as dye-sensitized solar cells, batteries, and conversion of CO2 to value-added products, etc. Furthermore, ionic liquid-FeP interactions are thought to be responsible for ionic liquid biodegradation and catalytic breakdown of ionic liquids. Despite the importance of ionic liquid-FeP interactions, there is a lack of information on what conformations ionic liquids adopt when presented to FeP and how thermodynamics of subsequent electron transfer reaction is affected. To begin to answer these questions, electronic structure calculations are performed to assess how the binding propensity of the homologous series of 1-n-alkyl-3-methylimidazolium [Cnmim]Cl (n = 2, 4, 6, 8, 10) to FeP is affected as the alkyl chain length and the initial conformation of the cation presented to FeP are varied. The conceptual density functional theory framework is then invoked to compute the electrophilicity index of the ionic liquid-FeP complex to glean insight into the ability of the complex to acquire an electron. Calculations suggest two equally likely conformations of ionic liquids with similar Gibbs free energy change; however, the enthalpic and entropic contributions differ based on the conformation adopted by ionic liquids which in turn affects the propensity of the subsequent electron transfer process. The importance of results is discussed in terms of experimentally observed alkyl chain length-dependent biodegradability of ionic liquids.

Catalytic pyrolysis of lignocellulosic and algal biomass using NaOH as a catalyst

AbstractIn this work, the pyrolysis of barley straw (BS) and brown algae (BA) mixed with NaOH as a catalyst was compared. Four different catalyst‐to‐biomass mass ratios (i.e., 6:100, 8:100, 10:100, and 12:100) and five pyrolysis heating rates were examined. The kinetic parameters (e.g., the activation energy and pre‐exponential factor) were evaluated using the Friedman method and kinetic models. For noncatalytic pyrolysis, the average activation energies for BS and BA samples were 139.71 and 183.19 kJ mol−1, respectively. However, the addition of catalyst generally increased the average activation energy of BS samples but decreased that of BA samples. The enthalpy change and Gibbs free energy change revealed that both catalytic and noncatalytic pyrolysis processes were nonspontaneous and endothermic, and the inclusion of catalyst increased the average entropy change of the BS samples but decreased that of the BA samples. Char and biochar yields after pyrolysis were also analyzed quantitatively. These observations provide insight into the differences in catalytic pyrolysis between lignocellulosic and algal biomass species.

Anisotropic Magnetic Polymeric Particles with a Controllable Structure via Seeded Emulsion Polymerization.

Magnetic polymer composites have been widely utilized in potential applications in material science, such as reduction of dyes, immunodiagnostics, biomedicals, and magnetically controllable photonic crystals owing to large surface areas, fast separation, and recyclable performance. In this work, anisotropic magnetic particles were prepared by seeded emulsion polymerization, with morphologies of "Fe3O4-shell", "hemisphere-like", "raspberry-like", "multiple lobes-like", and "sandwich-like". Poly(styrene/divinylbenzene/mono-2-(methacryloxy)ethyl succinate)@ Fe3O4 (P(St/DVB/MMES)@Fe3O4) were the seed microspheres, and P(St/DVB/MMES)@Fe3O4@polymer particles are achieved by seeded emulsion polymerizations. The morphology of the particles depends on polymerization conditions (monomer ratios and surfactant), particle properties, and so on. Then, the minimum surface free energy change principles were used to predict the equilibrium morphologies of the magnetic polymer composites. Through theory, the model gives the correct tendency and good agreement with the equilibrium morphology which was in tandem with TEM results. Lastly, after in situ surface deposition of Ag nanoparticles, magnetic composite particles with sandwich-like morphology were applied for the catalytic degradation of 4-nitrophenol (4-NP) reacting with NaBH4. The apparent rate coefficient is 0.0069 s-1, and it can keep mainly about 80% efficiency in catalysis after five cycles.

Removal of lead ions (Pb2+) from aqueous solution using chitosan/starch composite material: Experimental and density functional theory findings

AbstractTreatment of wastewater has become vital to prevent environmental pollution in recent years. Adsorption is an easily applicable, low-cost and efficient method and is the subject of this study. In this study, an adsorbent was synthesized to be used in heavy metal removal using chitosan and starch. The composite was characterized by Fourier transform infrared (FTIR) spectrophotometry, X-ray powder diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis. It was determined that the composite had an amorphous and compact structure. Adsorption experiments were carried out under the optimized parameters such as solution pH, concentration, adsorbent amount, equilibrium time, and temperature. It shows that during adsorption, with the increase in pH, the adsorption efficiency and adsorption capacity first increase and then a fluctuation occurs. The highest adsorption efficiency and Q value were reached at pH 3.46 as 78% and 0.038 mol/kg, respectively. Moreover, the adsorption capacity (Q) reached its highest value with a value of 0.067 mol/kg in the presence of 30 mg adsorbent. Equilibrium experiments were validated by the Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherm models. To investigate the adsorption mechanism, pseudo-first-order (PFO) and pseudo-second-order (PSO) kinetic models were used. It was determined that the adsorption process followed the D-R isotherm (R2 = 0.99) and PSO (R2 = 0.99). Therefore, the existence of chemical adsorption can be mentioned. Thermodynamic parameters enthalpy (∆H), Gibbs free energy (∆G) and entropy change (∆S) were investigated. The adsorbate-adsorbent interactions were studied by density functional theory (DFT).

In Situ Assembly of a Superaerophobic CoMn/CuNiP Heterostructure as a Trifunctional Electrocatalyst for Ampere-Level Current Density Urea-Assisted Hydrogen Production.

Urea electrolysis is a promising energy-efficient hydrogen production process with environmental benefits, but the lack of efficient and sustainable ampere-level current density electrocatalysts fabricated through simple methods is a major challenge for commercialization. Herein, we present an efficient and stable heterostructure electrocatalyst for full urea and water electrolysis in a convenient and time-efficient preparation manner. Overall, superhydrophilic/superaerophobic CoMn/CuNiP/NF exhibits exceptional performance for the hydrogen evolution reaction (HER) (-33.8, -184.4, and -234.8 mV at -10, -500, and -1000 mA cm-2, respectively), urea electro-oxidation reaction (UOR) [1.28, 1.43, and 1.51 V (vs RHE) at 10, 500, and 1000 mA cm-2, respectively], and oxygen evolution reaction (OER) [1.45, 1.67, and 1.74 V (vs RHE) at 10, 500, and 1000 mA cm-2, respectively]. Moreover, the superaerophobic CoMn/CuNiP/NF demonstrates promising potential in full urea (1.33, 1.57, and 1.60 V at 10, 500, and 1000 mA cm-2, respectively) and water (1.46 V, 1.78, and 1.86 at 10, 500, and 1000 mA cm-2, respectively) electrolysis. Based on X-ray photoelectron spectroscopy results, it was determined that the surface of the CoMn/CuNiP electrode was rich in redox pairs such as Ni2+/Ni3+, Cu+/Cu2+, Co2+/Co3+, and Mn2+/Mn3+, which are crucial for the formation of active sites for the OER and UOR, such as NiOOH, MnOOH, and CoOOH, thereby enhancing the catalytic activity. Besides, the in situ assembled CoMn/CuNiP/NF displayed highly stable performance for HER, OER, and UOR with high Faradaic efficiency for over 500 h. This research offers a simple and efficient method for manufacturing a high-efficiency and stable trifunctional electrocatalyst capable of delivering ampere-level current density in urea-assisted hydrogen production. Our density functional theory calculations reveal the potential of CoMn/CuNiP as an effective catalyst, enhancing the electronic properties and catalytic performance. The near-zero Gibbs free-energy change for HER underscores its promise, while reduced CO2 desorption energies and charge redistribution support efficient UOR. These findings signify CoMn/CuNiP's potential for electrochemical applications.

Most Monogenic Disorders Are Caused by Mutations Altering Protein Folding Free Energy.

Revealing the molecular effect that pathogenic missense mutations have on the corresponding protein is crucial for developing therapeutic solutions. This is especially important for monogenic diseases since, for most of them, there is no treatment available, while typically, the treatment should be provided in the early development stages. This requires fast targeted drug development at a low cost. Here, we report an updated database of monogenic disorders (MOGEDO), which includes 768 proteins and the corresponding 2559 pathogenic and 1763 benign mutations, along with the functional classification of the corresponding proteins. Using the database and various computational tools that predict folding free energy change (ΔΔG), we demonstrate that, on average, 70% of pathogenic cases result in decreased protein stability. Such a large fraction indicates that one should aim at in silico screening for small molecules stabilizing the structure of the mutant protein. We emphasize that knowledge of ΔΔG is essential because one wants to develop stabilizers that compensate for ΔΔG, but do not make protein over-stable, since over-stable protein may be dysfunctional. We demonstrate that, by using ΔΔG and predicted solvent exposure of the mutation site, one can develop a predictive method that distinguishes pathogenic from benign mutations with a success rate even better than some of the leading pathogenicity predictors. Furthermore, hydrophobic-hydrophobic mutations have stronger correlations between folding free energy change and pathogenicity compared with others. Also, mutations involving Cys, Gly, Arg, Trp, and Tyr amino acids being replaced by any other amino acid are more likely to be pathogenic. To facilitate further detection of pathogenic mutations, the wild type of amino acids in the 768 proteins mentioned above was mutated to other 19 residues (14,847,817 mutations), the ΔΔG was calculated with SAAFEC-SEQ, and 5,506,051 mutations were predicted to be pathogenic.

The Hydrophilicity of Samama Wood Surface Quality after Boron, Methyl Methacrylate Impregnation, and Heat Treatment

Indicators of surface roughness and surface-free energy can represent the improvement in wood surface quality. In this study, those two indicators were used to determine the change in the samama (Anthocephalus macrophyllus) wood surface following two modification steps, namely impregnation and heat treatment. The first step was boron impregnation in two forms applied separately, i.e., boric acid and borax. The second step was impregnation of methyl methacrylate followed by heat treatment at 90°C and 180°C. Surface roughness was determined following the ISO 4287:1997 standard, and surface free energy was analyzed using the Rabel Method. The results showed that the radial surface of samama wood naturally had a lower roughness than the tangential surface. Impregnation with boric acid, borax, and methyl methacrylate increased the wood surface roughness. However, heat treatment at 180°C tended to smooth the rough surface. Total surface free energy was altered after borax and methyl methacrylate impregnation. However, heat treatment seemingly withdrew the alteration. The polar components and dispersion contributed to total surface free energy with different compositions. In this study, the change in surface roughness was not congruent with the change in total surface free energy. Keywords: boron, heat treatment, impregnation, samama, surface free energy

Assessment of iridoids and their similar structures as antineoplastic drugs by in silico approach

Iridoids commonly found in plants as secondary metabolites have been reported to possess significant biological activities such as anticancer, antioxidant, hypoglycemic, antimicrobial etc. The strong interactions of iridoids with cyclic-dependent kinase 8 (CDK8) protein could show inhibitory effects that could modulate tumour growth. From the molecular docking calculations, some iridoids interacted effectively with the target CDK8 protein (PDB ID: 5ICP) with better binding affinities of −9.1, −9.0, −9.0, −8.9 kcal/mol, than that observed for the native ligand with −8.7 kcal/mol and for the reference compound gemcitabine with −6.9 kcal/mol. The GI50 values (<5 μM) obtained from graph-based signatures showed activity in breast, colon, leukaemia, and renal cancer cell lines. The IC50 predictions as CDK2 inhibitors were greater than 10 µM with type I non-allosteric binding mode. The stability analysis of protein-ligand complex from 125 ns long molecular dynamics simulations showed moderately smooth trajectories and RSMD value around 5 Å for the docked ligands. The binding free energy changes up to −47.65 ± 5.97 kcal/mol from MMGBSA method and −30.33 ± 5.40 kcal/mol from MMPBSA method hinted at the spontaneous nature of the complex formation. Furthermore, geometrical evaluators like RMSF, Rg, SASA, and hydrogen bond count also corroborated with the structural stability of the complexes and the capacity of hit molecules to inhibit the target, indicating its therapeutic potential against cancer. The toxicity and drug-likeness from ADMET predictions suggested experimental verification and that the proposed candidates could be employed for further trials in the development of safer and more effective anticancer drugs. Communicated by Ramaswamy H. Sarma

Synthesis, self-assembly and surface-active properties of alkyl halide mediated imidazolium monomeric surfactants

Two imidazolium monomeric surfactants, that is, 1-tetradecyl-1H-imidazole [14IM] and 1-hexadecyl-1H-imidazole [16IM] has been synthesized and characterized by 1H NMR,13C NMR, FTIR, HRMS spectroscopies and thermogravimetric analysis (TGA) for number and types of protons and carbon, functional groups, estimation of molecular weight and thermal stability of these compounds. The conductivity was measured in double distilled water at four different temperatures, 288, 293, 298, and 303 K. The results showed that these surfactants behave as weak electrolytes. The density and viscosity data have shown the existence of strong interactions between imidazolium surfactants and solvent (water) molecules. The results obtained from Root’s equation indicate that surfactant–solvent interactions are important than surfactant–surfactant interactions in dilute solutions, that is, below critical micellar concentration. The values of constants obtained from Einstein and Moulik equations have revealed that there was stronger and significant interaction between imidazolium surfactants and water molecules below critical micellar region. The surface tension parameters have indicated that these surfactants are good contenders to lower the surface tension of air/water interface. The results obtained from surface tension data have shown that standard change in free energy of micellization (ΔG°mic) and adsorption (ΔG°ads) were negative, indicating that these surfactants molecules have spontaneous tendencies to form micelles in solution at higher concentration and to get adsorb at the air/water interface at lower concentration. The TGA has indicated good thermally stability and activation energy for thermal decomposition was found in the range of 37.26.26–98.20.20 kJ/mol.

Spectroscopic insights with molecular docking and molecular dynamic simulation studies of anticancer drug 5-fluororouracil targeting human pyruvate kinase m2

This study was conducted to test the efficacy of 5-fluorouracil (5-FU) as an anticancer drug against the human pyruvate kinase isozyme M2 (PKM2) using spectroscopic, molecular docking and molecular dynamic simulation studies. PKM2 fluorescence quenching studies in the presence of 5-FU performed at three different temperatures indicates dynamic quenching processes with single-set of binding (n ≈ 1) profile. The biomolecular quenching constants (k q) and the effective binding constants (K b) obtained are shown to increase with temperature. The calculated enthalpy (ΔH) and entropy changes (ΔS) are estimated to be −118.06 kJ/mol and 146.14 kJ/mol/K respectively, which suggest the possible mode of interaction as electrostatic and hydrogen bonding. Further, these values were used to estimate the free energy changes (ΔG) and that increases with temperature. The negative ΔG values clearly indicates spontaneous binding process that stabilizes the complex formed between 5-FU and PKM2. Far-UV CD spectra of PKM2 in the presence of 5-FU shows decrease in α-helix contents which point towards the destabilization of secondary structure that weakens the biological activity of PKM2. The intrinsic fluorescence study and circular dichroism (CD) spectra showed minor conformational changes of PKM2 in the presence of 5-FU. Additionally, the results obtained from molecular docking and all-atom molecular dynamic simulation study supports the insight of the spectroscopic binding studies, and strengthens the dynamic stability of the complex between 5-FU and PKM2 through H-bonding. This study establishes a paradigm of 5-FU-PKM2 complexation and the efficacy of 5-FU that compromises the biological activity of the targeted PKM2. Communicated by Ramaswamy H. Sarma

Thermodynamics of Swelling of Poly(NIPAM‐co‐NTBA‐co‐HEAAm) Hydrogels

AbstractIn the present study, poly(N‐Isopropylacrylacrylamide‐co‐N‐tertiarybutylacrylamide‐co‐hydroxyethylcrylamide) (NIPAM‐co‐NTBA‐co‐HEAAm) hydrogels are prepared with variation of molar ratio of hydrophilic HEAAm and hydrophobic NTBA. The prepared hydrogels are characterized with elemental analysis and Fourier transform infrared (FTIR) spectroscopy. The thermodynamics of swelling properties of poly(NIPAM‐co‐NTBA‐co‐HEAAm) hydrogels have also been discussed. The experimental C/N ratios are comparable with the theoretical value. The enthalpy change of mixing ∆Hmix, entropy change of mixing ∆Smix, free energy change of mixing ∆Gmix are determined for swelling of hydrogels at 25 °C. The value of total free energy of hydrogel swelling is found to be negative which confirms the lower critical solution temperature (LCST) exhibited in all hydrogels and the volume change transition shows the thermoresponsive behavior. The values of ∆Smix increase and ∆Gmix decrease with increasing amount of hydrophobic NTBA content in the hydrogels. The values of free energy change of elasticity (∆Gel) are found to be increased with increasing the hydrophobic NTBA content followed by decrease in swelling percentage. Also, the transition temperature of the hydrogel is found to be decreased with increasing the hydrophobic NTBA.

Synthesis, optical properties, DNA, β-cyclodextrin interaction, hydrogen isotope sensor and computational study of new enantiopure isoxazolidine derivative (ISoXD)

A novel isoxazolidine derivative (ISoXD) dye was successfully synthesized and comprehensively characterized. In this study, we conducted a thorough examination of its various properties, including optical characteristics, interactions with DNA and β-cyclodextrin (β-CD), molecular docking, molecular dynamic simulation, and density functional theory (DFT) calculations. Our investigation encompassed a systematic analysis of the absorption and emission spectra of ISoXD in diverse solvents. The observed variations in the spectroscopic data were attributed to the specific solvent's capacity to engage in hydrogen bonding interactions. Remarkably, the most pronounced intensities were observed in glycol, which can establish many hydrogen bonds with ISoXD.Furthermore, our study revealed a significant distinction in the fluorescence behavior of ISoXD when subjected to different solvents, particularly between CHCl3 and CDCl3. Moreover, we explored the fluorescence intensity of the ISoXD complex in the presence of various metals, both in ethanol and water. The ISoXD complex exhibited a substantial increase of fluorescence upon interaction with different metal ions. The utilization of DFT calculations allowed us to propose an intramolecular charge transfer (ICT) mechanism as a plausible explanation for this quenching phenomenon. The interaction of ISoXD with DNA and β-CD was studied using absorption spectra. The binding constant (K) and the standard Gibbs free energy change (ΔGo) for the interaction between DNA and β-CD with ISoXD were determined. In docking study, ISoXD exhibited significant docking scores (−6.511) and MM-GBSA binding free energies (−66.27 kcal/mol) within the PARP-1 binding cavity. Its binding pattern closely resembles to the co-crystal ligand veliparib, and during a 100ns MD simulation, ISoXD displayed strong stability and formed robust hydrogen bonds with key amino acids. These findings suggest ISoXD's potential as a PARP-1 inhibitor for further investigation in therapeutic development.

Study on non-isothermal pyrolysis of Azadirachta Indica for kinetic triplets and thermodynamics evaluation

Exploring kinetics and thermodynamics of biomass pyrolysis process is imperative for optimizing the process. This study employs various model-free iso‐conversional methods and a model-fitting method to investigate the kinetics and thermodynamics of non-isothermal pyrolysis of Azadirachta indica biomass under four distinct heating rates of 10, 20, 30 and 40 °C/min. Average values of activation energy and pre-exponential factor ranged from 187.613 to 196.635 kJ/mol and 5.068×1014 − 1.178×1022 min−1, respectively, indicating an endothermic and complex nature of reaction. Integral master plots proved superior in revealing the reaction mechanism, although Criado's master plot unveiled a combination of reaction models, aligning with the intricate degradation mechanisms of biopolymers. The average enthalpy change, Gibbs free energy change and entropy change values spanned from 182.425 to 191.638 kJ/mol, from 167.288 to 173.742 kJ/mol and from 0.014 to 0.039 kJ/mol·K, respectively.

Environmental remediation through bimetallic sulphide-derived adsorbents: Prospects and progress

The present study explores the cost-effective and simple co-precipitation technique for the synthesis of bimetallic sulphide, Mn-Co-S@CTAB, nanomaterial, a hybrid of Manganese and Cobalt sulphide along with some surface modification through hexadecyltrimethylammonium bromide (CTAB). Congo red (CR) and Malachite green (MG) dyes were adsorbed out of their solutions onto the surface of produced nanomaterial and whole process has been studied. The adsorption mechanisms for the CR and MG sorption onto the surface of Mn-Co-S@CTAB has been proposed on the basis of investigation of thermodynamics and kinetics of the whole sorption process. To investigate the structural and morphological features of the synthesized nanomaterial, a systematic characterisation were done using FT-IR, P-XRD, SEM-EDX, TGA, TEM, XPS and Zeta Potential measurement were conducted. In order to achieve maximum efficiency, the sorption parameters, including the initial dye concentration, adsorbent dosage, temperature, contact time, and pH of the solutions have been optimized. The Mn-Co-S@CTAB demonstrated strong affinity for CR and MG dyes with sorption capacities of 263.15 and 163.93 mg g-1at 303 K. The positive value of enthalpy, ΔH, indicated the adsorption process to be endothermic for both dyes, while negative free energy change, ΔG, indicated the spontaneous nature of adsorption of these dyes. The Freundlich and Temkin isotherm models provided the closest fit to the data for isotherm investigations for CR and MG sorption onto Mn-Co-S@CTAB, while kinetics of reaction in the examined temperature range followed pseudo-second order kinetics.

Sorption of hexavalent chromium adsorption and its subsequent removal from Aqueous Environment using algae Sargassum myriocystum

The present study focuson the adsorption of hexavalent chromium with Sargassum myriocystum, algae and the outcomes of various parameters such as size of sorbent, contact time, temperature, sorbent dosage and agitating speed were enhanced with aid of response surface methodology. The maximum adsorption of hexavalent chromium in its optimized conditions were determined as solution temperature of 35oC, size of sorbent for 0.5284 mm 36 BSS mesh ,contact time (1 hour), agitating speed (50 rpm) and sorbent dosage (4.309 g).The utmost removal was 99% . Isotherm studies revealed that Langmuir model is fitting the algae with a hexavalent chromium uptake of 61.5384mg/g. Thermodynamic study revealed that it is endothermic in nature and values of Gibb’s free energy, enthalpy and entropy change are in accordance. The sorbents were characterized with FTIR and SEM. FTIR studies revealed the presence of a few functional groups like carboxylic acid, amino and hydroxyl in hexavalent chromium adsorption. Pseudo I order kinetics are in accordance for this process. From above studies it can be concluded that Sargassum myriocystum had good removal capacity for hexavalent chromium from fabricated solutions.

Measuring Hydroxyl Exchange Rates in Glycans Using a Synergistic Combination of Saturation Transfer and Relaxation Dispersion NMR.

Molecular recognition events mediated by glycans play pivotal roles in controlling the fate of diverse biological processes such as cellular communication and the immune response. The affinity of glycans for their target receptors is governed primarily by the hydrogen bonds formed by hydroxyl groups decorating the glycan surface. Hydroxyl exchange rate constants are therefore vital parameters that report on glycan structure and dynamics. Here we present a strategy for characterizing hydroxyl hydrogen/deuterium (H/D) exchange in glycans that employs a synergistic combination of 13C chemical exchange saturation transfer (CEST) and Carr-Purcell-Meiboom-Gill relaxation dispersion (CPMG) NMR methods. We show that the combination of CEST and CPMG experiments facilitates the sensitive detection of the small (∼0.1 ppm) two-bond deuterium isotope shift on a 13C nucleus when the attached hydroxyl group fluctuates between protonated and deuterated states. This shift is leveraged for measuring site-specific kinetic H/D exchange rate constants as well as thermodynamic free energies of isotope fractionation. The CEST and CPMG modules are integrated with a selective J-cross-polarization scheme that provides the flexibility for rapid characterization of H/D exchange at a specific hydroxyl site. Moreover, our approach enables the precise isothermal measurement of hydroxyl exchange rate constants without the need for cumbersome isotope labeling. The H/D exchange rate constants of three different glycans assessed using this method highlight its potential for detecting transient intra- and intermolecular hydrogen bonds. In addition, the trends in H/D exchange rate constants establish site-specific steric accessibility as a key determinant of solvent exchange dynamics in glycans.

The Entropy of van der Waals Fluid.

Thermodynamic state functions are fundamental quantities in many fields. In this work, the van der Waals (vdW) equation of state and calculation formulas of state functions are derived with statistical thermodynamic method in three-dimensional (3D) and two-dimensional (2D) spaces. The heat capacity at constant volume (CV,m ) or area (CA,m ) is exactly the same as that of ideal gas, but the heat capacity at constant pressure (Cp,m ) and other state functions are different from those of ideal gas. The vdW equation of state is a cubic equation, which leads to the fact that the entropy and free energy changes of vdW fluid can be expressed as explicit expressions of volume rather than pressure. Therefore, the adsorbate entropy at constant area can still be theoretically proven to have a linear relationship with the gas-phase entropy at constant volume. However, the linear correlation between it and gas-phase entropy at constant pressure is no longer strictly true in theory. In addition, since the vdW equation of state is applicable to both gas and liquid, the linear correlation between adsorbate entropy and liquid-phase entropy can also be found. At last, the reference state for real gas or fluid at a constant molar volume is suggested.