Catalytic, kinetic and thermodynamic properties of stabilized Bacillus stearothermophilus alkaline protease

Bacillus stearothermophilus alkaline protease was conjugated to several oxidized polysaccharides of different chemical structure. The conjugates were evaluated for the kinetic and thermodynamic stability. The conjugated enzyme with oxidized pectin had the highest retained activity (79.5%) and the highest half-life (T_1/2) at 50°C and pH 9.0. Compared to the native protease, the conjugated preparation exhibited lower activation energy (E_a), lower deactivation constant rate (k_d), higher T_1/2, and higher D values (decimal reduction time) within the temperature range of 50-60°C. The thermodynamic parameters for irreversible inactivation of native and conjugated protease indicated that conjugation significantly decreased entropy (ΔS*) and enthalpy (ΔH*) of deactivation. The calculated value of activation energy for thermal denaturation (E_ad) for the conjugated enzyme was 20.4KJmole^-1 higher over the native one. The results of thermodynamic analysis for substrate hydrolysis indicated that the enthalpy of activation (ΔH*) and free energy of activation (free energy of substrate binding) ΔG*_E-S and (ΔG*), (free energy of transition state) ΔG*_E-T values were lower for the modified protease. Similarly, there was significant improvement of k_cat, k_cat/K_m values. The enzyme proved to be metalloprotease and significantly stimulated by Ca²⁺ and Mg²⁺ whereas Hg²⁺, Fe³⁺ Cu²⁺ and Zn²⁺ inhibited the enzyme activity. There was no pronounced effect on substrate specificity after conjugation.

Quantum chemical studies, natural bond orbital analysis and thermodynamic function of 2,5-dichlorophenylisocyanate

In this work, vibrational spectral analysis on the solid state of 2,5-dichlorophenylisocyanate have been investigated both the experimental and theoretical vibrational data indicate the presence of various functional groups within the title of molecule. The equilibrium geometry, bonding features, harmonic vibrational frequencies, infrared and Raman intensities have been calculated with the help of density functional theory methods. The assignments of the vibrational spectra have been carried out with the help of normal coordinate analysis following the scaled quantum mechanical force field calculations. The first hyperpolarizability (βtot) of this noval molecular system and related properties (μ, α and Δα) are calculated using B3LYP/6-31+G(d) and B3LYP/6-311++G(d,p) method on the finite-field approach. Second order perturbation energies and electron density in the bonding and anti-bonding orbitals are discussed on the basis of NBO analysis. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule.

Effect of drying methods on the moisture sorption isotherms and thermodynamic properties of mint leaves

Mint leaves were dried by three different types of dryers, namely; tray, freeze and distributed (indirect)-type solar dryer. Sorption isotherms of fresh, solar, tray and freeze dried mint were determined at temperatures of 15 °C, 25 °C and 35 °C over a range of relative humidities (10-90%). The effect of drying method on the water sorption isotherms of dried mint samples was evaluated. Experimental data were used to determine the best models for predicting the moisture sorption content of mint. Among nine sorption models tested, Peleg, GAB, Lewicki and modified Mizrahi equations gave the best fit to experimental data. The sorption data were analyzed for determination of monolayer moisture content, density of sorbed water, number of adsorbed monolayers, percent bound water, and surface area of adsorbance. The experimental data were also used to determine some thermodynamic properties of mint.

Thermodynamic properties and hysteresis loops in a hexagonal core-shell nanoparticle

We applied Monte Carlo simulation to investigate the thermodynamic properties and hysteresis loops of the hexagonal core-shell nanoparticle described by a ferrimagnetic mixed-spin (3/2, 5/2) Ising model. The results revealed the significance of the single-ion anisotropy, exchange coupling, external magnetic field in dominating various thermodynamic quantities and hysteresis loops. We obtained the variation of the critical temperature with various parameters. Under certain parameter conditions, the system may exhibit rich multiple-loop hysteresis behaviors, depending on the competition among the physical parameters.

Inclusion complex thermodynamics: The β-cyclodextrin and sertraline complex example

Thermodynamic properties for β-cyclodextrin-Sertraline inclusion process was calculated at the density functional theory (DFT) level using the PBE0 functional with 6-31G(d,p), 6-31++G(d,p) and 6-311++G(2df,p) basis sets. Electron correlation was evaluated through Møller-Plesset second-order perturbation theory (MP2). The standard statistical thermodynamic approach was used to assess the entropic contribution to the Gibbs free energy value. According to our results, inclusion of hydration waters to describe the reactants and products in the complex formation reaction model is crucial in order to reproduce the experimental data and seems very coherent with basics thermodynamics yielding good agreement with experiment.

Moisture sorption isotherms and thermodynamic properties of mexican mennonite-style cheese

Moisture adsorption isotherms of fresh and ripened Mexican Mennonite-style cheese were investigated using the static gravimetric method at 4, 8, and 12 °C in a water activity range (aw) of 0.08-0.96. These isotherms were modeled using GAB, BET, Oswin and Halsey equations through weighed non-linear regression. All isotherms were sigmoid in shape, showing a type II BET isotherm, and the data were best described by GAB model. GAB model coefficients revealed that water adsorption by cheese matrix is a multilayer process characterized by molecules that are strongly bound in the monolayer and molecules that are slightly structured in a multilayer. Using the GAB model, it was possible to estimate thermodynamic functions (net isosteric heat, differential entropy, integral enthalpy and entropy, and enthalpy-entropy compensation) as function of moisture content. For both samples, the isosteric heat and differential entropy decreased with moisture content in exponential fashion. The integral enthalpy gradually decreased with increasing moisture content after reached a maximum value, while the integral entropy decreased with increasing moisture content after reached a minimum value. A linear compensation was found between integral enthalpy and entropy suggesting enthalpy controlled adsorption. Determination of moisture content and aw relationship yields to important information of controlling the ripening, drying and storage operations as well as understanding of the water state within a cheese matrix.

Structural characterization, catalytic, kinetic and thermodynamic properties of Aspergillus oryzae tannase

Tannase (EC.3.1.1.20) from Aspergillus oryzae was purified using ammonium sulphate precipitation (75%), gel filtration chromatography through Sephadex G-100, and G-200. The purified enzyme was monomeric protein with a molecular mass of 106kDa. The activation energy for tannic acid hydrolysis was 32.6kJmol^-1 and its temperature quotient (Q₁₀) was 1.0. The pK_a1 and pK_a2 values of acidic and basic limbs of the active site residues were 4.6 and 6.4. The calculated values of thermodynamic parameters for tannic acid hydrolysis, were as follows: ΔH*=30.02kJmol^-1, ΔG*=59.75kJmol^-1 ΔS*=-95.90Jmol^-1K^-1, (ΔG*_E-S)=3.66kJmol^-1 and ΔG*_E-T -12.61kJmol^-1. The pure enzyme exhibited K_m, V_max and k_cat of 4.13mM, 3507Umgprotein^-1 and 551.4s^-1_. The calculated half-life time at 40, 45, 50, 55, 60, and 70°C was 955.15, 142.0, 30.28, 17.88, 8.23 and 2.95min, respectively. The thermodynamic parameters for irreversible thermal inactivation at different temperatures (40-70°C) were determined. The enzyme was activated by Ca²⁺, and Mg²⁺ while Hg²⁺, Fe²⁺, and Cu²⁺ strongly inhibited it. Hydrolysis of tannic acid by the pure enzyme indicated that gallic acid was the end-product.

Pyrolysis behaviors and thermodynamics properties of hydrochar from bamboo (Phyllostachys heterocycla cv. pubescens) shoot shell

Hydrothermal carbonization (HTC) was employed to produce hydrochar from bamboo (Phyllostachys heterocycla cv. pubescens) shoot shell (BS) at severity (combined temperature and time) of 4.83-7.69. The pyrolysis and thermodynamics properties of the hydrochars were fully investigated. The results showed that the hydrochar properties (solid yield, C content, H/C and O/C atomic ratios, pyrolysis yield, pyrolysis index, formation of enthalpy, exergy, LHV, and HHV) of BS were highly dependent on severity and could be expressed by dose-response functions. The rapid variations of the hydrochar properties appeared at severity of 5.93-6.59. The pyrolysis temperature interval for the maximum weight loss shifted from 300 to 400°C at hydrothermal severity less than 6.59 to 400-500°C at hydrothermal severity greater than 6.59. The hydrochar thermal stability increased greatly with the severity increasing. And the thermodynamic properties of hydrochar approached those of lignin model compounds as the hydrothermal severity was greater than 6.59.

Effect of sodium chloride on the thermodynamic, rheological, and microstructural properties of field pea protein isolate/chitosan complex coacervates

The effect of increasing sodium chloride concentration (c_NaCl, 0-0.4 M) on the formation and rheological and microstructural properties of field pea protein isolate (FPPI)/chitosan (Ch) complex coacervates was investigated. The maximum turbidity and zeta potential of FPPI/Ch mixtures consistently decreased with the increasing c_NaCl. The tertiary conformation of FPPI was altered to facilitate the aggregation of FPPI/Ch complexes via hydrophobic interactions. Changes in thermodynamic parameters during the titration of FPPI with Ch confirmed the addition of NaCl could cause the inhibition of electrostatic complexation and the induction of non-Coulombic interactions. FPPI/Ch complex coacervates exhibited first enhanced and then weakened viscoelastic properties and an initially tightened and then a loosened microstructure as the c_NaCl increased. In summary, appropriate c_NaCl favors the formation of FPPI/Ch complex coacervates with improved functionalities via the coordination of promoted hydrophobic interactions and inhibited electrostatic attractions, facilitating the application of this protein ingredient in food development.

Determination of kinetic triplet, thermal degradation behaviour and thermodynamic properties for pyrolysis of a lignocellulosic biomass

Kinetic triplet, thermal degradation behaviour and thermodynamic properties of peanut shells were determined on the basis of non-isothermal thermogravimetric experiments conducted at three different heating rates under N₂ atmosphere. A single differential peak was observed for the devolatilization stage. The kinetic triplet of devolatilization stage was determined using Coats-Redfern and a combined method consisting the utilization of isoconversional and Criado methods. Kinetic validation revealed that the kinetic triplet determined using the combined method described the experimental values more precisely. The reaction mechanism ascertained by the combined method was D5-D3 combination. The E_a value was strong function of conversion, and computed using isoconversional methods (Boswell, Flynn-Wall-Ozawa, Starink, Tang) between 169 and 268 kJ/mol. Entalphy, entrophy and Gibbs energy changes were computed in 164-259 kJ/mol, -37-141 J/(mol.K) and 173-187 kJ/mol ranges, respectively. The comprehensive pyrolysis index values were also calculated, and shown to increase with increasing heating rate.

An analysis of structural phase transition and allied properties of cubic ReN and MoN compounds

The present work aims at the study of structural, elastic, electronic, and thermodynamic properties of transition metal nitrides: ReN and MoN in the zinc-blende (B3) phase. The plane wave pseudopotential and norm-conserving pseudopotential have been applied in Quantum-Espresso code based on density-functional theory (DFT). The results show a first-order phase transition from B3 to B1 (rock-salt) structure at 42 GPa and 2.5 GPa for ReN and MoN respectively. The elastic behaviors of these compounds are also unfolded in this work. The brittleness of the ReN and ductility of MoN is identified with the help of Pugh's index and Poisson's ratio. The strong anisotropic behaviors of both compounds are detected under the influence of pressure. The electronic and bonding features of proposed compounds are evaluated by means of band structures, the density of states (DOS), Fermi surface, and charge density plots. The obtained results forecast the metallic behavior and ionic bonding of ReN and MoN in both phases: B3 and B1. Additionally, various thermodynamic properties are also investigated under high pressures and temperatures (from 0 to 2000 K). Conceivably, these properties are reported for the first time in the B3 structure of these compounds and will be useful for many applications in modern technologies as well.

Molecular characterization, catalytic, kinetic and thermodynamic properties of protease produced by a mutant of Bacillus cereus-S6-3

The proteolytic strain Bacillus cereus-S6-3 was subjected to mutagenic treatments viz. UV irradiations and methyl methane sulfonate (MMS). The obtained mutant strain, B. cereus-S6-3/UM90 showed 1.34 fold over the parent strain. Molecular characterization of proteases from the parent (PP/S6-3) and mutant (PM/UM90) strains indicated that they were consisted of two domains and binds a zinc ion and 4 calcium ions in the active site. Amino acid sequence alignment of PM/UM90 protease showed 19 amino acid residues were substituted compared to that of the wild-type enzyme. However, both proteases contained equal number of aromatic and hydrophobic amino acids. Protease from PM/UM90 showed an effective improvement in thermal properties in terms of reaction temperature, t_1/2, the values of k_d, activation energy (E_a), and decimal reduction time (D) within the temperature range from 60 to 80 °C. In addition, the kinetic and thermodynamic parameters for substrate hydrolysis (i.e., K_m, V_max, ΔH*, ΔG*, ΔS*, k_cat, V_max/K_m, k_cat/K_m, ΔG*_E-T and ΔG*_E-S) showed a significant improvement of the catalytic efficiency for PM/UM90 protease. Furthermore, the correlation between thermodynamic properties and the patterns of amino acid substitution of wild-type enzyme to has been discussed.

Thermodynamics of sorption isotherms and storage stability of spray dried sweetened yoghurt powder

Sorption isotherm is a quantitative approach to predict the shelf life of dried foods. Adsorption isotherms of spray dried sweetened yoghurt powder (SYP) were determined by static gravimetric technique at 20, 30, 40 and 50 °C. The data obtained were fitted to eight different sorption models. A non-linear least square regression analysis was adopted to evaluate the model constants. The experimental sorption data were best fitted to four parameter Peleg model. The monolayer moisture contents found from GAB model were 4.88, 4.54, 3.86 and 3.52% at 20, 30, 40 and 50 °C, respectively. The maximum net isosteric heat of sorption and sorption entropy of SYP were 9.399 kJ/mol and 20.28 J/mol K, respectively. The Gibb's free energy change for sorption was in the range 3436.19-303.91 J/mol. The storage stability in terms of moisture content, thiobarbituric acid, free fatty acid, hydroxymethyl furfural values and starter counts of SYP packed in aluminium laminated polyethylene (ALPE) and low density polyethylene (LDPE) were studied along with their change kinetics. The relationship between the water vapour permeability of packaging materials and adsorbed moisture (determined from GAB equation) in powder was used to predict the shelf life and was predicted as 28 and 44.44 days in LDPE and ALPE pouches, respectively.

Equation of state and thermodynamic properties for mixtures of H 2 O , O 2 , N 2 , and CO 2 from ambient up to 1000 K and 280 MPa

Supercritical water oxidation (SCWO) is an effective technique to treat wet organic wastes. Its modeling requires an accurate calculation of thermodynamic properties. In this work an equation of state (EOS) is proposed which accurately predicts the thermodynamic state of mixtures of water, oxygen, nitrogen, and carbon dioxide for a wide range of compositions, temperatures, and pressures including supercritical conditions. The EOS includes a volume translation, an evolved α -function and non-quadratic mixing rules. The introduced parameters are regressed to experimental data. From the pressure-explicit EOS, enthalpy, specific heats at constant volume and constant pressure, and fugacity coefficients are derived and calculated. The binary mixtures H 2 O / O 2 , H 2 O / N 2 , H 2 O / CO 2 , N 2 / CO 2 as well as the ternary mixture H 2 O / O 2 / N 2 are well predicted by the proposed EOS with relative errors below 10% and 15%, respectively. The region of low temperature and high pressure is most difficult to predict with relative errors up to 20%.

A first principle study of the structural, electronic, and temperature-dependent thermodynamic properties of graphene/MoS2 heterostructure

After an initial assessment of the structural and electronic properties of graphene, monolayer MoS₂, and graphene/MoS₂ bilayer hetero-structure, the temperature-dependent thermodynamic properties of graphene/MoS₂ bilayer hetero-structure are examined by using density functional theory calculations. The structure, bandgap, partial density of states, and thermodynamic properties of graphene, monolayer MoS₂ and graphene/MoS₂ system are investigated and analyzed. Findings from the present study are in good agreement with the previously reported theoretical and experimental studies. Monolayer MoS₂ and graphene form a stable Van der Waals heterostructure owing to their negative binding energy, and the system acts as a zero-bandgap semiconductor. Debye temperature and the heat capacity of graphene, MoS₂ monolayer, and graphene/MoS₂ system are calculated from phonon dispersion relations to be 2100 K, 600 K, and 1400 K, and 0.7 J/g.K, 0.218 J/g.K, and 0.46 J/g.K, respectively. Introduction of graphene into the MoS₂ semiconductor is, therefore, found to improve the overall thermodynamic properties of the composite as graphene preserved its superior thermal properties. The findings will be beneficial to calculate thermal conductivity of the graphene/MoS₂ heterostructure for minimizing the temperature effect in electronic or optoelectronic devices.

Synthesis and spectroscopic characterization on 4-(2,5-di-2-thienyl-1H-pyrrol-1-yl) benzoic acid: A DFT approach

A complete structural and vibrational analysis of the 4-(2,5-di-2-thienyl-1H-pyrrol-1-yl) benzoic acid (TPBA), was carried out by ab initio calculations, at the density functional theory (DFT) method. Molecular geometry, vibrational wavenumbers and gauge including atomic orbital (GIAO) (13)C NMR and (1)H NMR chemical shift values of (TPBA), in the ground state have been calculated by using ab initio density functional theory (DFT/B3LYP) method with 6-311G(d,p) as basis set for the first time. Comparison of the observed fundamental vibrational modes of (TPBA) and calculated results by DFT/B3LYP method indicates that B3LYP level of theory giving yield good results for quantum chemical studies. Vibrational wavenumbers obtained by the DFT/B3LYP method are in good agreement with the experimental data. The study was complemented with a natural bond orbital (NBO) analysis, to evaluate the significance of hyperconjugative interactions and electrostatic effects on such molecular structure. By using TD-DFT method, electronic absorption spectra of the title compound have been predicted and a good agreement with the TD-DFT method and the experimental one is determined. In addition, the molecular electrostatic potential (MEP), frontier molecular orbitals analysis and thermodynamic properties of TPBA were investigated using theoretical calculations.

Quantum chemical studies, vibrational analysis, molecular structure, first order hyper polarizability, NBO and HOMO-LUMO analysis of 3-hydroxybenzaldehyde and its cation

FT-IR spectroscopy has been applied to investigate the potential nonlinear optical (NLO) material 3-hydroxybenzaldehyde (3HBA). The equilibrium geometry, Fukui function, harmonic vibrational frequencies, infrared intensities, and thermodynamic properties of 3HBA and its cation were calculated by HF/6-31G(d,p) and density functional theory B3LYP/6-31G(d,p), B3LYP/6-311++G(d,p) methods. The first order hyperpolarizability (βtotal) of this molecular system and related properties (β, μ, and Δα) are calculated based on the finite-field approach. Stability of the molecule arising from hyperconjugative interactions, charge delocalization and intramolecular hydrogen bond-like weak interaction has been analyzed using natural bond orbital (NBO) analysis by using B3LYP/6-311++G(d,p) method. The results show that electron density (ED) in the σ(*) and π(*)anti-bonding orbitals and second-order delocalization energies E((2)) confirm the occurrence of intramolecular charge transfer (ICT) within the molecule. The thermal stability of 3HBA and its cation is studied by the thermogravimetric analysis (TGA). The harmonic-vibrational frequencies were calculated and the scaled values have been compared with experimental FT-IR spectrum. The observed and the calculated frequencies are found to be in good agreement. The experimental spectrum also coincides satisfactorily with those of theoretically constructed spectrograms.

Phonon stability, electronic structure results, mechanical and thermodynamic properties of RbSbO3 and CsSbO3 perovskite oxides: Ab initio investigation

Cubic perovskite oxides RbSbO₃ and CsSbO₃ have been investigated for structural stability, electronic results, elastic, mechanical stability and thermodynamic results by most accurate density functional theory (DFT). The optimization has been completed using Local density approximation (LDA) and Generalized gradient approximation (GGA) within the scheme of Perdew, Burke and Ernzrhof (PBE). The ground state optimized results present minimum energy within GGA for both compounds. Band structure and density of state results both present the metallic nature for these compounds. The mechanical properties like Young's modulus, Bulk modulus etc. have been deduced from elastic values. RbSbO₃ was found to have more resistance to compression as compared to strength CsSbO₃. Both the materials were found to have brittle nature from Poisson's ratio (υ), Cauchy's pressure (C₁₂-C₄₄) and Pugh ratio (B/G) criteria. The melting temperature was calculated to be 2148 ± 300 K, 1746 ± 300 K, respectively for RbSbO₃ and CsSbO₃. Pressure and temperature variation has been used for calculation of thermodynamic parameters within quasi-harmonic Debye approximation. The nature of Bulk modulus, cell volume, specific heat capacity and thermal expansion has been computed in the temperature range of 0 K-900 K and pressure varied from 0 GPa to 15 GPa.

Structural, electronic, optical and thermodynamic properties of AeBi2O6 (Ae = Sr and Ba): Insights from first principles study

First principles calculations based on Full-Potential Linearized Augmented Plane-Wave (FP-LAPW) method have been carried out to study the structural, electronic and optical properties of AeBi₂O₆ (Ae = Sr and Ba) compounds. Optimal crystal structure is found out by optimizing lattice constants and internal parameters of constituent atoms using the Generalized Gradient Approximation as proposed by Wu-Cohen (GGA-WC). While the electronic, dielectric and optical properties of considered materials are investigated using original Becke-Johnson (BJ) potential as it reproduces very reasonable indirect band gaps as compared with experimental ones with value of 1.769 eV and 1.822 eV for SrBi₂O₆ and BaBi₂O₆, respectively. The interactions between O-2p and Bi-5s-5p, which are responsible of photocatalytic activity of studied compounds, are demonstrated. Finally, the Debye quasi-harmonic model is used to calculate the thermodynamic properties including bulk modulus, heat capacities, thermal expansion, Debye temperature and entropy of AeBi₂O₆ compounds. All of them are investigated for wide range of temperature up to 1200 K and of pressure up to 45 GPa.

High pressure and high temperature investigation of metallic perovskite SnTaO3

High pressure electronic, elastic, mechanical, and thermodynamic properties of cubic perovskite SnTaO₃ have been explored with density function theory (DFT), and the quasi-harmonic Debye model has been applied for the incorporation of high temperature. The experimental lattice constant has been used for the optimization of structure. The optimization results present the paramagnetic (PM) nature of the compound. The spin dependent electronic band structures at ambient conditions and under high pressure present the metallic nature with complete uniformity for the majority and minority spin states. The mechanical properties, such as Young's modulus and bulk modulus, have been calculated and suggest an increase in stiffness and hardness of the material under the application of pressure. The thermodynamic properties, such as specific heat and Grüneisen parameter, have been predicted in the temperature range of 0 to 1000 K and pressure range of 0 to 60 Gpa.

Effectiveness and mechanisms of the adsorption of carbendazim from wastewater onto commercial activated carbon

The wide application of fungicides is becoming one of the main causes of water pollution. Activated carbon (AC) is a frequently-used adsorbent in water treatment. In this work, aiming to obtain a better understanding of fungicides on AC, carbendazim was selected as a model fungicide in water. The effects of AC dosage, adsorption temperature, adsorption time and pH value of solution on carbendazim adsorption by AC were investigated. When the initial concentration of carbendazim was 500 mg L^-1 and the volume of wastewater was 25 mL, the optimum dosage of AC and reaction time was determined to be 0.3 g and 150 min, respectively. The pH ranging from 3.0 to 10.0 exhibited little effect on the adsorption capability of AC. The higher the adsorption temperature was, the better adsorption capacity was. Adsorption capacity could reach 32.31 mg g^-1 under the optimal adsorption conditions. The kinetics study reveals that the adsorption of carbendazim occurred on the surface of adsorbent during initial stage. The adsorption data was well fitted by Langmuir adsorption isotherm, indicating that the adsorption process was monolayer adsorption. The thermodynamic experiments confirmed that the adsorption of carbendazim was an endothermic process with the coexistence of physical and chemical adsorption. Because the main components of AC used in this research work is amorphous carbon with low impurity and its surface has not been modified with additional functional groups, the conclusion of the study was easy to be replicated by repeated experiments. Therefore, the findings of this study could guide the adsorption of carbendazim onto the other kinds of AC with high specific surface area, and provide useful information for application of commercial AC in treatment of fungicides wastewater.

APUAMA: a software tool for reaction rate calculations

APUAMA is a free software designed to determine the reaction rate and thermodynamic properties of chemical species of a reagent system. With data from electronic structure calculations, the APUAMA determine the rate constant with tunneling correction, such as Wigner, Eckart and small curvature, and also, include the rovibrational level of diatomic molecules. The results are presented in the form of Arrhenius-Kooij form, for the reaction rate, and the thermodynamic properties are written down in the polynomial form. The word APUAMA means "fast" in Tupi-Guarani Brazilian language, then the code calculates the reaction rate on a simple and intuitive graphic interface, the form fast and practical. As program output, there are several ASCII files with tabulated information for rate constant, rovibrational levels, energy barriers and enthalpy of reaction, Arrhenius-Kooij coefficient, and also, the option to the User save all graphics in BMP format.

Thermodynamic sorption of red cabbage extract (Brassica oleracea L. var. capitata L. f. rubra) encapsulated by spray drying

Red cabbage aqueous extract acidified with 2 % citric acid was spray-dried using gum Arabic as encapsulating agent. The concentration of anthocyanin in the powder was 253.45 ± 10.82 mg/100 g of dry basis and antioxidant activity of 4.6 ± 0.2 mmol trolox/kg of dry basis. The sorption isotherms were determined at 15, 25 and 35 °C, and the GAB model was the one that best adjusted to the experimental data. The differential enthalpy and entropy for moisture levels up to 2 g of water/g of dry basis decreased to a minimum value of -4.36 kJ/mol and -0.019 kJ/molK respectively, and then increased in magnitude with the rise in moisture content to levels close to the free moisture with a spontaneous process, governed by the entropy. The spreading pressure increased with the rise in water activity for all temperatures, while net integral enthalpy and entropy decreased with the rise in moisture content reaching levels close to 10 kJ/mol and 0.025 kJ/molK, respectively.

Thermal and hydrodynamic properties of coronavirus at various temperature and pressure via molecular dynamics approach

COVID-19 is an epidemic virus arising from a freshly discovered coronavirus. Most people involved with the coronavirus will experience slight to moderate respiratory disease and recover without needing particular therapy. In this work, the atomic stability of the coronavirus at different thermodynamic properties such as temperature and pressure, was studied. For this purpose, the manner of this virus by atomic precession was described with a molecular dynamics approach. For the atomic stability of coronavirus description, physical properties such as temperature, total energy, volume variation, and atomic force of this structure were reported. In molecular dynamics approach, coronavirus is precisely simulated via S, O, N, and C atoms and performed Dreiding force field to describe these atoms interaction in the virus. Simulation results show that coronavirus stability has reciprocal relation with atomic temperature and pressure. Numerically, after 2.5 ns simulation, the potential energy varies from - 31,163 to - 26,041 eV by temperature changes from 300 to 400 K. Furthermore, this physical parameter decreases to - 28,045 eV rate at 300 K and 2 bar pressure. The volume of coronavirus is another crucial parameter to the stability description of this structure. The simulation shows that coronavirus volume 92% and 14% increases by 100 K and 2 bar variation of simulation temperature and pressure, respectively.

In Silico vibrational spectroscopic investigation on antioxidant active Mannich base 1-[anilino (phenyl) methyl] pyrrolidine-2,5-dione

The antioxidant active Mannich base 1-[anilino (phenyl) methyl] pyrrolidine-2,5-dione (APMPD) have been synthesized and its FT-IR and FT-Raman vibrational spectra were recorded within the region of 4000cm(-1), 50cm(-1) respectively. The molecular geometric parameters of APMPD have been computed using HF and DFT model theories. The energies of APMPD are calculated for all the eight possible conformers using B3LYP method at 6-311++G(d,p) basis set. From the computational results, the M1 conformer was identified as the most stable conformer of APMPD. The stable conformer was compared with experimental crystal geometry, which again fortifies the results of conformer analysis. The fundamental vibrations of the molecule are assigned according to the characteristic region and the literature report. The predicted highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy gap provide vivid idea on charge transfer behavior of APMPD. The molecular electrostatic potential (MEP) and Mulliken charge analysis indicate the feasible electrophilic and nucleophilic reactive sites on APMPD. The thermodynamic properties (heat capacity, entropy, and enthalpy) of the title compound at various temperatures are calculated in gas phase.