Calculation Of Internal Energy Research Articles

A review on synthetic strategy, molecular pharmacology of indazole derivatives, and their future perspective.

With different nitrogen-containing heterocyclic moieties, Indazoles earn one of the places among the top investigated molecules in medicinal research. Indazole, an important fused aromatic heterocyclic system containing benzene and pyrazole ring with a chemical formula of C7 H6 N2 , is also called benzopyrazole. Indazoles consist of three tautomeric forms in which 1H-tautomers (indazoles) and 2H-tautomers (isoindazoles) exist in all phases. The tautomerism in indazoles greatly influences synthesis, reactivity, physical and even the biological properties of indazoles. The thermodynamic internal energy calculation of these tautomers points view 1H-indazole as the predominant and stable form over 2H-indazole. The natural source of indazole is limited and exists in alkaloidal nature (i.e., nigellidine, nigeglanine, nigellicine, etc.) found from Nigella plants. Some of the FDA-approved drugs like Axitinib, Entrectinib, Niraparib, Benzydamine, and Granisetron are being used to treat renal cell cancer, non-small cell lung cancer (NSCLC), epithelial ovarian cancer, chronic inflammation, chemotherapy-induced nausea, vomiting, and many more uses. Besides all these advantages regarding its biological activity, the main issue about indazoles is the less abundance in plant sources, and their synthetic derivatives also often face problems with low yield. In this review article, we discuss its chemistry, tautomerism along with their effects, different schematics for the synthesis of indazole derivatives, and their different biological activities.

COMPARISON OF ENERGY SAVING METHODS FOR DISTILLATION OF LIQUID MIXTURES

The analysis and review of the scientific literature on methods and approaches to energy saving in distillation, as one of the most energy-intensive processes for the separation of binary and multicomponent mixtures was carried out. Directions of the scientific literature are highlighted, showing the relevance of the thermodynamic method assessment of separation processes. A comparative analysis of various methods of energy conservation in the separation of liquid binary mixtures by the distillation method is performed (a binary mixture of benzene-toluene was chosen as an example). A conventional distillation column as well as a column with a heat pump and a column with heat integration were considered. As a result of the calculation experiment for each option performed using the Aspen Plus software package the optimal column parameters were determined - the total number of stages and the position of feed stage. The heat consumption in the column boiler was taken as the objective function. It is also shown that with the same characteristics of the columns, the best way to organize the process for separating the selected mixture is to compress the steam stream from rectifying profile of the column with its subsequent use in the boiler of the stripping profile according to the principle of a heat pump. It was established by a calculation experiment that heat integration by compressing steam from rectifying profile of the column and supplying it to the stripping profile gives significantly less energy saving. The calculation of internal energy saving by distillation column was carried out and it was shown that the distributed heat removal from the plates of the rectifying profile of the column and the supply of this heat to the stripping profile plates reduces internal energy saving and leads to an additional increase in heat consumption in the boiler.

Thermodynamics of the formation of surface PtO2 stripes on Pt(111) in the absence of subsurface oxygen.

This paper examines the thermodynamics of PtO2 stripes formed as intermediates of Pt(111) surface oxidation as a function of the degree of dilation parallel to the stripes, using density functional theory and atomistic thermodynamics. Internal energy calculations predict 7/8 and 8/9 stripe structures to dominate at standard temperature and pressure, which contain 7 or 8 elevated PtO2 units per 8 or 9 supporting surface Pt atoms, respectively. Moreover, we found a thermodynamic optimum with respect to mean in-stripe Pt-Pt spacing close to that of α-PtO2. Vibrational zero point energies, including bulk layer contributions, make a small but significant contribution to the stripe free energies, leading to the 6/7 stripe being most stable, although the 7/8 structure is still close in free energy. These findings correspond closely to experimental observations, providing insight into the driving force for oxide stripe formation and structure as the initial intermediate of platinum surface oxidation, and aiding our understanding of platinum catalysts and surface roughening under oxidative conditions.

Discrete and Weyl density of states for photonic dispersion relation

The current density of states (DOS) calculations do not take into account the essential discreteness of the state space, since they rely on the unbounded continuum approximation. Recently, discrete DOS based on the quantum-mechanically allowable minimum-energy interval has been introduced for the quadratic dispersion relation. In this work, we consider systems exhibiting a photonic (photon-like) dispersion relation and calculate the related density and number of states (NOS). Also, a Weyl’s conjecture-based DOS function is calculated for photons and acoustic phonons at a low-frequency limit, by considering the bounded continuum approach. We show that the discrete DOS function reduces to expressions of bounded and unbounded continua in the appropriate limits. The fluctuations in discrete DOS completely disappear under accumulation operators. It is interesting that relative errors of NOS and DOS functions with respect to discrete ones have exactly the same character as the ones of the quadratic dispersion relation. Furthermore, the application of discrete and Weyl DOS for the calculation of internal energy of a photon gas is presented and the importance of discrete DOS is discussed. It is shown that the discrete DOS function given in this work needs to be used whenever the low energy levels of a physical system are heavily occupied.

Organism Encumbrance of Cardiac Surgeon During Surgery.

Introduction:Most everyday activities, performed over a long period leads to performance degradation of skeletal muscles as well as spinal column which is reflected in the reduction of maximum force, reduction of the speed of response, reducing control of the movement etc. Although until now many mathematical models of muscles are developed, very small number takes into account the fatigue, and those models that take into account changes in the characteristics of muscles for extended activities, generally considered tiring under certain conditions. Given that the current models of muscle fatigue under arbitrary conditions of activation and load are very limited, this article presents a new model that includes scale of muscles overload.Material and Methods:There are three female cardiac surgeons working performing these surgeries in operating rooms, and their average anthropometric measures for this population is: a) Weight: 62 kg; b) Height: 166 cm. Age: 45 taken in the calculation within the CATIA software, that entity is entitled to 50% of healthy female population that is able to execute these and similar jobs. During the surgery is investigated the two most common positions: position “1” and “2”. We wish to emphasize that the experiment or surgical procedure lasted for two positions for five hours, with the position “1” lasted 0.5 hours, and position “2” lasted about 4.5 hours. The additional load arm during surgery is about 1.0 kg.Results:The analysis was done in three positions: “Operating position 1”, “Operating position 2 ‘, and each of these positions will be considered in its characteristic segments. These segments are: when the body takes the correct position, but is not yet burdened with external load, then when the surgeon receives the load and the third position when the load is lifted at the end of the position. Calculation of internal energy used on the joints is carried out in the context of software analysis of this model using CATIA R5v19. The proposed model is based on CATIA software model, which consists of visual indicators of the burden on certain parts of the body as well as the forces acting in these parts of the body.Conclusion:Based on these indicators to define which muscles, as well as that part of the skeletal system is overloaded, what is the position and what needs to be done that specific load be within permitted limits.

Molecular Modeling of Toxic Indole Derivatives from High Temperature Cooking

More than two decades ago, Japanese scientists discovered a new family of highly mutagenic compounds classified as heterocyclic aromatic amines from roasted meat and grilled Fish. This group of compounds will form the basis of this investigation from a theoretical perspective. In order to simulate high temperature cooking and explore the thermochemical properties of these compounds, high level quantum calculations were employed. Accordingly, the theoretical behaviour of indole derivatives; isoindazole, 1-methyl indole, 4,7-dimethyl isoindazole and carbazole were explored at a pressure of 1 atmosphere over a wide range of pyrolysis temperatures (323-923 K) typically at temperature increments of 50 K. Ab initio analytical gradients at MP2 level of theory with 3-21G and 6-31G(d,p) basis sets and Molecular Mechanics (MM) with universal force field (UFF) from Gaussian 03 computational platform were used for geometry optimization, internal energy calculations, molecular orbitals, and vibrational frequencies. It was observed that the internal energy for isoindazole at 323 K was 75.80 kcal/mol whereas that of carbazole was 123.78 kcal/mol under similar conditions of pressure and temperature. The stability of these molecular compounds decreased with increase in pyrolysis temperature. To make decent conclusions on the potency of these indole derivatives and their effect on human health, toxicity values were estimated using Quantitative Structural Activity Relationship (QSAR) method found in HypeChem computational software. Toxicity indices for isoindazole, 1-methyl indole, 4,7-dimethyl isoindazole and carbazole were -0.16, 0.01, 0.14 and -0.07 respectively, while those for their corresponding radicals were -0.12, -0.21, 0.19 and -0.17. These values point to highly hydrophilic species which indicate that they are very toxic. The thermochemical, and electronic properties of these compounds and their analog radicals will be presented. Additionally, theoretical NMR chemical shifts for the most toxic by-product of high temperature cooking are also reported in this work.

Modeling of Lithium Ion Batteries Employing Grand Canonical Monte Carlo and Multiscale Simulation

In the current investigation modeling of two half cells (LiMn2O4 cathode and carbon anode) followed by modeling of the complete cell of the battery employing Grand Canonical Monte Carlo simulations to evaluate open circuit potential and energetic of the process involved had been carried out. Current model takes into account the effect of electrolyte and temperature variations on various battery parameters like open circuit potential, cell current, cell voltage and free energy of Li+ intercalation/deintercalation. Estimation of open circuit potential (OCV) of Lithium ion batteries becomes vital as it is a crucial parameter in (i) estimating diffusion coefficient of lithium in the electrode material during charge/discharge process, (ii) obtaining entropy of the reaction and internal energy calculations and (iii) understanding thermal runaway problems. The strong dependence of OCV with the state of charge (SOC) of the battery and temperature makes the prediction more difficult. To avoid computational tediousness, Grand Canonical Monte Carlo technique coupled with multiscale simulation is employed to predict experimental OCV of LiMn2O4 cathode material in the presence of electrolyte solution.

Calculation of Internal Energy and Pressure of Dense hydrogenPlasma by Direct Path Integral Monte Carlo Approach

The internal energy and pressure of dense hydrogenplasma are calculated by the direct path integral Monte Carlo approach.The Kelbg potential is used as interaction potentials both betweenelectrons and between protons and electrons in the calculation. Thecomplete formulae for internal energy and pressure in dense hydrogenplasma derived for the simulation are presented. The correctness of thederived formulae are validated by the obtained simulation results. Thenumerical results are discussed in details.

Simple Analytic Expression with High Precision for theBarker-Henderson Diameter

A fitting procedure is proposed to establish two analytic approximateexpressions for the complicated Barker-Henderson (BH) diameter withLennard-Jones potential in two temperature ranges. Considering that thedifferentiation is a process enlarging the errors and the integrationdecreasing the errors and that the derivative of BH diameter isimportant in the calculation of internal energy, we propose to fit thederivative directly, instead of usually fitting the original functionand subsequently deriving its derivative. The simplicity and precisionof two expressions developed are superior to the extensively usedexpressions in literature. The one with following form only has anaverage fitting 0.0063% in the reduced temperature range (0.4⩽kT/ε⩽15), and can be extrapolated to a widertemperature range (0.4⩽kT/ε⩽50) with anaverage error 0.13%, which is d/σ = 1.1755 + 0.02878ln τ-0.2072τ1/4 + 0.00463τ3/4.

Monte Carlo studies of the conformational statistics of polymers. Polyethylene

AbstractThe conformational distribution of unperturbed polyethylene (PE) has been studied utilizing the Monte Carlo approach. The results are in excellent agreement with experiments on the average dimensions of PE chains, as well as with the molecular scattering function obtained in mixtures of deuterated and hydrogenous PE at 400 K. Maps of the free energy as a function of two consecutive torsional angles confirm that an approximate description of the conformational distribution of PE can be given in terms of three rotational isomeric (RIS) states. The location of the states and the corresponding energy and entropy parameters, which can be separately evaluated from the Monte Carlo results, are compared with literature results obtained by internal energy calculations for butane and pentane.

A difference in the shapes of intermolecular potentials between phospholipid model molecules. Relation to the ripple phase

Intermolecular van der Waals energy maps are calculated for three model molecules of phospholipids to demonstrate the effect of the head size of a molecule on its steric properties. The calculation of internal energy, including van der Waals and Coulomb interaction of model bilayers, gives the possible relation to the existence of the ripple phase.

Free energy and internal energy of electron-screened plasmas in a modified hypernetted-chain approximation.

We report results of Helmholtz-free-energy and internal-energy calculations using the modified hypernetted-chain (MHNC) equation method, in the formulation of Lado, Foiles, and Ashcroft [Phys. Rev. A 28, 2374 (1983)], for a model plasma of ions linearly screened by electrons. The results are compared with HNC calculations (no Bridge term), with variational calculations using a hard-spheres reference system, and with a numerical fit of Monte Carlo simulations.

Conformation-activity relationship of tachykinin neurokinin A (4-10) and of some [Xaa8] analogues.

NKA (4-10), the C-terminal heptapeptide fragment (Asp-Ser-Phe-Val-Gly-Leu-Met-NH2) of tachykinin NKA, is more active than the parent native compound in the interaction with the NK-2 receptor. Substitution of Gly8 with the more flexible residue beta-Ala8 increases its selectivity with respect to other two known receptors (NK-1 and NK-3), whereas substitution with either D-Ala8 or GABA8 deprives the peptide of its biological activity. These findings can be interpreted by a conformational analysis based on NMR studies in DMSO-d6 and in a DMSO-d6/H2O cryoprotective mixture combined with internal energy calculations. NKA(4-10) is characterized by a structure containing a type I beta-turn extending from Ser5 to Gly8, followed by a gamma-turn centered on Gly8, whereas for [beta-Ala8]NKA(4-10) is possible to suggest a type I beta-turn extending from Ser5 to beta-Ala8, followed by a C8 turn comprising beta-Ala8 and Leu9 and by another beta-turn extending from beta-Ala8 to the terminal NH2. The preferred conformation of [beta-Ala8]NKA(4-10) is not compatible with models for NK-1 and NK-3 agonists proposed on the basis of rigid peptide agonists [Levian-Teitelbaum et al. (1989) Biopolymers 28, 51-64; Sumner & Ferretti (1989) FEBS Lett. 253, 117-120]. The preferred solution conformation of [beta-Ala8]NKA(4-10) may thus be considered as a likely bioactive conformation for NK-2 selective peptides.

New insights on μ/δ selectivity of opioid peptides: Conformational analysis of deltorphin analogues

The message domain of dermorphin (Tyr-D-Ala-Phe), a natural mu-opioid heptapeptide, has long been considered the main cause of the high mu selectivity of this peptide and of its analogues. The recent discovery, in the skin of Phyllomedusa sauvagei (i.e., the same natural source of dermorphin) and of Phyllomedusa bicolor of deltorphins, challenges this belief. Deltorphins, in fact, are three heptapeptides characterized by a message domain typical of mu-selective peptides, but endowed of an extremely high delta selectivity, the highest of all natural opioid peptides. A conformational analysis of dermorphin and deltorphins, based on nmr studies in DMSO and cryoprotective mixtures and internal energy calculations, showed that the enormous differences in receptor selectivity can be interpreted on the basis of receptor models for mu and delta opioids that recognize the same beta-turn in the N-terminal part, but discriminate for the conformation and polarity of the C-terminal part. Here we present the synthesis, biological activity, and conformational analysis in solution of three deltorphin analogues with very similar constitution, but with different net charge, different location of negative residues, or even without negative residues, which confirm these hypotheses and show that His4 can play a specific structural role.

A comparison of internal energy calculation methods for diatomic molecules

Various methods of calculating the internal energy of diatomic molecules are studied. An accurate and efficient method for computing the eigenvalues of the vibrational Schrödinger equation for an arbitrary potential is developed. The method is based on a finite-element discretization using the cubic Lobatto element. A combination of spectrum slicing and the Laguerre algorithm is used to solve for the eigenvalues. A simple method to compute the quasibound states is presented. For N2 molecules, all vibrational–rotational states of 11 available electronic potentials are computed and summed to obtain the exact internal energy function with temperature. The total computation required 314 sec of CPU time on NASA’s Cray 2 computer. Various approximate models are discussed and compared with exact calculations. It is shown that the splitting of the macroscopic internal energy into separate electronic, rotational, and vibrational energies is not justified at high temperatures.

The flexibility of the nucleic acids: (II). The calculation of internal energy and applications to mononucleotide repeat DNA.

Results concerning the flexibility of mononucleotide repeat DNA are presented using a novel methodology, denoted "SIR", to describe continuous changes in the structure of the nucleic acid. This methodology, combined with internal energy calculations and analytical energy gradients allows us to determine optimal conformations of poly(dG).poly(dC) and poly (dA).poly(dT) in both the A and B forms, taking into account the influence of the solvent medium and explicit counterions. Subsequently, several different types of distorsion of these optimal structures are investigated. It is shown that excellent correlation with experimental results concerning coupled changes in structural variables is obtained and several new correlations are also detected.

Rotamers arising from restricted motions and electromc interactions of acetoxymethyl groups in carbohydrates

The two dimensional conformational spaces available for acetoxymethyl groups in carbohydrates are reported. The studies were performed on two molecules differing in their C-4 configurations, i.e. gluco and galacto. The acetoxymethyl group was assigned a mean geometry derived from the computation of 19 equivalent groups as found in pertinent acetylated carbohydrates. The internal energy calculations were performed by including the partitioned contributions arising from the non-bonded energies, electrostatic interactions, and torsion energy. An instability rating of 3 kcal/mol was assigned to conformations involving peri interactions, i.e., trans–gauche and gauche–gauche forms in gluco and galacto carbohydrates, respectively. The results which are best described in term of topology show that several conformations corresponding to the trans and gauche states of the C—O single bond are preferred. However, significant shifts from perfect staggering are observed. The predicted regions of low energy are found to be in good agreement with experimental data from crystal structures of acetylated carbohydrates.

Conformational analysis of (1 → 6)-α-D-glucan

The three-dimensional conformational space available to α-D-(1 → 6)-linked glycans is reported. The isoenergy conformational maps were prepared by defining three rotatable bonds between rigid glucopyranose residues. The calculation of internal energy considered van der Waals, torsional, and hydrogen-bond factors. The results of the analysis may be used to predict properties of (1 → 6)-α-D-homoglycans having either an axial or equatorial hydroxyl group at C-4. The theoretical isoenergy-maps are in good agreement with experimental data from crystal structures of oligosaccharidcs having the same linkage. The results are discussed in terms of the biological role of polysaccharides containing the α-D-(1 → 6) linkage.

Vibrational calculations on the biphenyl crystal: The mixing between low frequency internal and lattice modes

The low frequency optically active crystal vibrations of biphenyl have been calculated using atom–atom interaction potentials. The agreement with experimental data is good. It has been found that torsional and translational modes are very strongly coupled. The conformational change of the biphenyl molecule from gaseous to crystal state and the corresponding changes in the internal force field are discussed. Some assignments are reexamined taking into account the calculated results. The heat of sublimation is well reproduced from internal energy calculations.