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Imidazolium-based ionic liquids (ILs) have been regarded as green solvents owing to their unique properties. Among these, the melting point is key to their excellent performance in applications such as catalysis, biomass processing, and energy storage, where stability and operational temperature range are critical. The utilization of neural networks for forecasting the melting point is highly significant. Nevertheless, the excessive selection of descriptors obtained by density functional theory (DFT) calculations always leads to huge computational costs. Herein, this study strategically selected only 12 kinds of quantum chemical descriptors by employing a much more efficient semi-empirical method (PM7) to reduce computational costs. Four principles of data pre-processing were proposed, and the innovative use of a simulated annealing algorithm to search for the lowest energy molecular conformation improved accuracy. Based on these descriptors, a multi-layer perceptron neural network model was constructed to efficiently predict the melting points of 280 imidazolium-based ILs. The R2 value of the current model reached 0.75, and the mean absolute error reached 25.03 K, indicating that this study achieved high accuracy with very little computational cost. This study reveals a strong correlation between descriptors and melting points. Additionally, the model accurately predicts unknown melting points of imidazolium-based ILs, achieving good results efficiently. [ABSTRACT FROM AUTHOR]

In this paper, the critical wind speed of flutter has been predicted by using two-dimensional computational fluid dynamics (CFD) model side by side with the empirical formula (Selberg's formula, 1961). The deck section of the Great Belt Bridge's main span has been used herein as a reference among other sectional varieties. For each case of the examined sections, the width was changed case by case, while its depth maintained unchanged. Both of the two methods, the semi-empirical using the "CFD" simulation and the empirical formula have been employed to predict the critical wind speed of flutter for a variety of the (width/depth) ratio and the natural frequency ratio (torsional/vertical). The results were obtained from the semi-empirical method and validated by comparison with wind tunnel test for typical section model of the Great Belt Bridge presented in the literature, and also compared with the empirical method. The results were represented graphically for each method and they have indicated the variation of the critical speed in terms of the section dimension and its natural frequencies, and furthermore, the change of the difference between the two methods was represented too. [ABSTRACT FROM AUTHOR]

Accurate conformational energetics of molecules are of great significance to understand maby chemical properties. They are also fundamental for high-quality parameterization of force fields. Traditionally, accurate conformational profiles are obtained with density functional theory (DFT) methods. However, obtaining a reliable energy profile can be time-consuming when the molecular sizes are relatively large or when there are many molecules of interest. Furthermore, incorporation of data-driven deep learning methods into force field development has great requirements for high-quality geometry and energy data. To this end, we compared several possible alternatives to the traditional DFT methods for conformational scans, including the semi-empirical method GFN2-xTB and the neural network potential ANI-2x. It was found that a sequential protocol of geometry optimization with the semi-empirical method and single-point energy calculation with high-level DFT methods can provide satisfactory conformational energy profiles hundreds of times faster in terms of optimization. [ABSTRACT FROM AUTHOR]

To propose a simplified semi-empirical method for predicting the additional stress on the underlying layer of the rigid pile-net composite foundation, a finite element analysis, which verified by a series of field tests and model tests, are carried out. Focusing on the equivalent entity method recommended by Technical code for composite foundation, the equivalent frictional resistance coefficient, which is a key factor affecting the additional stress, is deduced through the static balance theory and β-method. Finite element analyses, including 432 tests, are conducted to analyse the effect of pile length, pile spacing, thickness of cushion layer, embankment height and geological conditions on the key coefficient. Then, a simplified semi-empirical model for predicting the key coefficient as well as the additional stress is proposed based on numerical results. The accuracy of the proposed model is verified by the good agreement between the experimental results and numerical results. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Remote Sensing is the property of Editorial Office of Journal of Remote Sensing & Science Publishing Co. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• Co-MOF synthesized and characterized by FT-IR, X-RD, XPS, and SEM-EDX. • CNTs and FCNTs added to enhance of the supercapacitance performance. • Electrochemical measurements determine the supercapacitance of all MOFs. • Semi-empirical theoretical method applied and the energy gaps calculated. • FCNTs@Co-MOF is the most excellent superiorcapacitor. Supercapacitor offers high power density and quick charge/discharge speed. Herein, a cobalt-metal organic framework (Co-MOF) is synthesized, and the chemical structure is investigated via XRD, FTIR, XPs, and SEM-EDX. Photoluminescence and diffuse reflectance spectroscopy measurements determine the optical properties and band gap. The band gap of Co-MOF is calculated and found to be 1.94 eV, indicating its capability to be applied as a supercapacitor. Carbon nanotubes (CNTs) and functionalized carbon nanotubes (FCNTs) are mixed with Co-MOF to form CNTs@Co-MOFs and FCNTs@Co-MOFs, respectively. The performance of these MOFs as supercapacitors is evaluated using electrochemical measurements. According to the analysis of the super capacitance of the synthesized compounds, FCNTs@Co-MOF shows the highest specific supercapacitance of 454 F g−1, whereas Co-MOF and CNTs@Co-MOF have 263 F g−1 and 338 F g−1, respectively. Besides, the semi-empirical quantum method is used to assess the relationship between the electronic and the experimental data. Experimental and theoretical results recommended the usage of the investigated MOFs as superior supercapacitors. [ABSTRACT FROM AUTHOR]

Semi-empirical satellite method is widely used in estimating global horizontal irradiance (GHI), where various clear-sky models, cloud index (CI) and clear-sky index (CSI) derivation methods are available. This study aims to optimize the semi-empirical satellite model for 5-minute GHI estimation from four aspects: satellite-bands, CI and CSI derivation methods, and clear-sky models. The results show that it achieves better GHI estimates using the blue band, CI derived from monthly fixed upper and lower bounds, and a piecewise CI-to-CSI function. There is no significant difference in all-sky GHI estimation for the clear-sky models regarding normalized root mean squared error (nRMSE, 25.19%–25.53%), which is comparable with the referenced physical model. Clouds cause the largest uncertainty, where the nRMSE is in the range of 37.60%–38.36% in cloudy days and 31.12%–31.54% in cloudy periods. In the application of semi-empirical method with different clear-sky models, Ineichen–Perez has the highest bias of -4.62% in clear days and -3.93% in cloudless periods. REST2 outperforms McClear with slightly lower nRMSE and normalized mean bias error (nMBE) under all sky conditions. McClear is recommended due to its global availability. Modified Ineichen–Perez produces the lowest nRMSE and nMBE using clear-sky GHI as the GHI estimates for clear periods, therefore has the potential for improvements in physical methods. • 5-minute GHI is estimated by the optimized semi-empirical method and GOES-16 imagery. • Different ABI bands, CI and CSI derivation methods are compared for GHI estimation. • The modified Ineichen–Perez clear-sky model is introduced in GHI estimation. • The GHI estimation result is comparable with the referenced physical method. • The modified Ineichen–Perez model yields better clear-sky GHI than physical models. [ABSTRACT FROM AUTHOR]

A numerical and an empirical method for calculating nonlinear load-settlement curves for shallow foundations on sand are examined and used in a new methodology. Both methods have merits and drawbacks. The drawbacks are overcome by the methodology proposed and verified in the paper. This methodology combines the merits of each method. For this purpose, a modification of the empirical method is proposed that accounts for the finite initial soil stiffness at very small strains. Computer programs with sophisticated nonlinear stress-strain relationships, such as Hardening Soil Small in Plaxis 2D, which are versatile in solving complex foundation problems, can cover strains from very small to large. When the foundation soil is layered, it is proposed to fit such a numerical load-settlement curve against the modified empirical relationship for each sand layer separately. This requires cone penetration tests, measurements of the shear wave velocity, and basic laboratory tests. The methodology is described and applied at two locations where load tests on footings were carried out. At one location there was a top layer of clay, which was also taken into account. The results of the application of the proposed methodology are very good.

Providing a reasonable forecast of the required properties of intermetallic compounds (hereinafter also referred as intermetallides or IM) is an important scientific and commercial problem, which may be solved by focusing scientific researches and permanent generation of knowledge in this field. To date, researches in chemistry and physics of IM have been developing empirically for a simple reason, due to the complexity of describing the relationship between the crystal structure and chemical bonds, and, therefore, between all the properties of IM. IM is mainly characterized by metal type of chemical bond, as well as specific metallic properties. At the same time, among IM, there are also salt-like compounds with ionic bond, i.e. valency compounds formed from elements of different chemical nature, being stoichiometric compounds. The examples of such compounds are compounds with intermediate bond type, i.e. ionmetal and covalently-metal, as well as covalent bond types (e.g., NaAu). In the series of compounds of Mg with elements of the IV subgroup, along with decreasing the difference in the electrochemical characteristics of the components, the change in the IM properties is observed, from those peculiar to ionic compounds (for example, Mg2Si, Mg2Ge) to the properties typical of metals (Mg2Pb), etc. Due to the fact that lanthanides form the largest group of elements of the periodic system occurring in nature, and Mg is a relatively active chemical element in terms of IM formation (for example, it forms three IM with cadmium - Mg3Cd, MgCd and MgCd3), its oxides in slag provide decreasing average silicon content and increasing the stability of the silicon content in iron, being an important process indicator in the course of physicochemical reactions occurring in a blast furnace (for example, in the process of iron production). The presence of Si impurity (along with O, Au, Ti, V, Zr) produces the greatest effect on efficiency of solar cells, etc. [1–3]. Based on the foregoing, it is very important to study the state function, i.e. enthalpy of magnesium-lanthanide systems, rich in magnesium, and, based on the results of computer simulation, taking into account molecular dynamics method and other similar studies [4–8], to model regularities of changes in melting enthalpy of IM of the mentioned systems. The issue of modeling the pattern of change in melting enthalpy of IM of magnesium-lanthanide (Mg-Ln) magnesium-rich systems is considered based on systematic analyzing melting enthalpy of IM of Mg-Ln magnesium-rich system, including Mg2Ln, Mg3Ln and equimolar compound MgLn, implemented using semi-empirical method developed by N.S. Poluektov.

Gouge and dent are common mechanical defects in oil and gas pipelines. These defects with plastic strain cause stress concentration in the pipelines. Plastic strain is dependent on initial deformation and spring-back behavior of materials. Therefore, they reduce the fatigue life of pipelines. In this paper, the strain-base fatigue life analysis is investigated in pipelines with smooth dent or combination smooth dent and gouge defects under cyclic internal pressure. For this purpose, elastic-plastic multilinear isotropic hardening finite element simulation was used to investigate the effects of various factors, such as residual stress of dent, amplitude internal pressure, pipe geometry, gouge geometry, and smooth dent geometry on stress concentration factor (SCF). Finally, a new method is proposed for predicting the fatigue life of pipelines with uniform dent and uniform dent and gouge combination defects. The model is presented based on the Smith-Watson-Topper (SWT) criterion. A set of fatigue life test specimens with various pipe materials, size and geometry were prepared and tested. The specimens carried a smooth dent, as well as a combination of smooth dent and gouge defects, results of which were collected to validate those obtained based on the proposed model. The results of the predicted tests using the developed formula showed a good correlation to practical experiments. [ABSTRACT FROM AUTHOR]

Malarial parasites have been reported for moderate-high resistance towards classical antimalarial agents and henceforth development of newer novel chemical entities targeting multiple targets rather than targeting single target will be a highly promising strategy in antimalarial drug discovery. Herein, we carried out molecular modeling studies on 2,4-disubstituted imidazopyridines as anti-hemozoin formation inhibitors by using Schrödinger's molecular modeling package (2020_4). We have developed statistically robust atom-based 3D-QSAR model (training set, R 2 = 0. 8 7 0 9 ; test set, Q 2 = 0. 5 2 8 7 ; F value = 5 2. 9 ; root-mean-square error, RMSE = 0. 5 7 ; standard deviation, SD = 0. 3 2 6). Our molecular docking, in-silico ADMET analysis showed that dataset molecule 37, has highly promising results. Our ligand-based virtual screening resulted in top five ZINC hits, among them ZINC73737443 hit was observed with lesser energy gap, i.e. 7.85 eV, higher softness value (0.127 eV), and comparatively good docking score of − 10.2 kcal/mol. Our in-silico analysis for a proposed hit, ZINC73737443 showed that this molecule has good ADMET, in-silico nonames toxic as well as noncarcinogenic profile. We believe that further experimental as well as the in-vitro investigation will throw more lights on the identification of ZINC73737443 as a potential antimalarial agent. The present study reports molecular modelling studies on 2,4-disubstituted imidazopyridines as antihemozoin formation inhibitors by using Schrodinger's molecular modelling suite. Furthermore, with the use of unique virtual screening approach and theoretical studies on ZINC hits, we proposed the identification of ZINC73737443 hit as a potential antimalarial agent. [ABSTRACT FROM AUTHOR]

A numerical and an empirical method for calculating nonlinear load-settlement curves for shallow foundations on sand are examined and used in a new methodology. Both methods have merits and drawbacks. The drawbacks are overcome by the methodology proposed and verified in the paper. This methodology combines the merits of each method. For this purpose, a modification of the empirical method is proposed that accounts for the finite initial soil stiffness at very small strains. Computer programs with sophisticated nonlinear stress-strain relationships, such as Hardening Soil Small in Plaxis 2D, which are versatile in solving complex foundation problems, can cover strains from very small to large. When the foundation soil is layered, it is proposed to fit such a numerical load-settlement curve against the modified empirical relationship for each sand layer separately. This requires cone penetration tests, measurements of the shear wave velocity, and basic laboratory tests. The methodology is described and applied at two locations where load tests on footings were carried out. At one location there was a top layer of clay, which was also taken into account. The results of the application of the proposed methodology are very good. [ABSTRACT FROM AUTHOR]

Copyright of e-Zbornik: Electronic Collection of Papers of the Faculty of Civil Engineering is the property of University of Mostar, Faculty of Civil Engineering, Architecture & Geodesy and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Landslides can be triggered by natural and human activities, threatening the safety of buildings and infrastructures. Mapping potential landslide runout zones are critical for regional risk evaluation. Although remote sensing technology has been widely used to discover unstable areas, an entire landslide runout zone is difficult to identify using these techniques alone. Some simplified methods based on empirical models are used to simulate full-scale movements, but these methods do not consider the kinematic uncertainties caused by random particle collisions in practice. In this paper, we develop a semi-empirical landslide dynamics method considering kinematic uncertainties to solve this problem. The uncertainties caused by the microtopography and anisotropy of the material are expressed by the diffusion angle. Monte Carlo (MC) simulations are adopted to calculate the probability of each cell. Compared with the existing Flow-R model, this method can more accurately and effectively estimate runout zones of the Yigong landslide where random particle collisions are intense. Combining the D-InSAR technique, we evaluate the runout zones in the Jinsha River from June 2019 to December 2020. This result shows that the method is of great significance in early warning and risk mitigation, especially in remote areas. The source area of the landslide and DEM resolution together affect the number of MC simulations required. A landslide with a larger volume requires a larger diffusion angle and more MC simulations.

In this study, we developed a new method for determining the density of liquids using the Compton backscattering technique. The principle of this method is based on the change in the area under a single scattering peak versus the liquid density. The linear calibration curve of the ratio R versus the density is required to determine the density of an unknown liquid (R is the ratio of the area under a single scattering peak for a liquid relative to that for water). In the proposed method, the calibration curve is completely constructed based on a simulation using the MCNP5 code. The method involves combining a simulation with an experiment as a semi-empirical method. Using this method, we determined the density of four liquids comprising acetonitrile, glycerol, nitric acid, and sulfuric acid, and the maximum deviations between the reference densities and measured values were less than 1.4%, except in the case of sulfuric acid, which was approximately 4.5%. The results obtained in this study strongly suggest that the proposed method is suitable and feasible for application. • Method for determining density of liquids based on simulated and experimental data. • Density of liquids determined using a proposed semi-empirical method. • Differences between experimental and simulated values are insignificant. • Relative deviations less than 4.5% between measured and reference values. [ABSTRACT FROM AUTHOR]

A CeBr3 scintillation detector was applied for in situ gamma-ray spectrometry for radioactivity assessment of soil. The full energy peak count-to-radioactivity conversion factors were determined using a semi-empirical method. In-situ measurements using the detector system were implemented in three open fields. The radioactivity concentration of natural radionuclides in the soil and the detection limit for artificial radionuclides assuming artificial radionuclide deposited on the soil surface in a radiation emergency situation were estimated. The radioactivity concentration of 40K, 208Tl and 214Bi by in situ gamma-ray measurement agreed well with the sampling analysis results within 5%. [ABSTRACT FROM AUTHOR]

The calibration methods of neutron-measuring devices such as the neutron survey meter have advantages and disadvantages. To compare the calibration factors obtained by the shadow cone method and semi-empirical method, 10 neutron survey meters of five different types were used in this study. This experiment was performed at the Korea Atomic Energy Research Institute (KAERI; Daejeon, South Korea), and the calibration neutron fields were constructed using a 252Californium (252Cf) neutron source, which was positioned in the center of the neutron irradiation room. The neutron spectra of the calibration neutron fields were measured by a europium-activated lithium iodide scintillator in combination with KAERI's Bonner sphere system. When the shadow cone method was used, 10 single moderator-based survey meters exhibited a smaller calibration factor by as much as 3.1–9.3% than that of the semi-empirical method. This finding indicates that neutron survey meters underestimated the scattered neutrons and attenuated neutrons (i.e., the total scatter corrections). This underestimation of the calibration factor was attributed to the fact that single moderator-based survey meters have an under-ambient dose equivalent response in the thermal or thermal-dominant neutron field. As a result, when the shadow cone method is used for a single moderator-based survey meter, an additional correction and the International Organization for Standardization standard 8529-2 for room-scattered neutrons should be considered.

Quantitative Structure and Activity Relationship (QSAR) analysis of 13 benzothiazoles derivatives compound as antimalarial compounds have been performed using electronic descriptor of the atomic net charges (q), dipole moment (μ), ELUMO, EHOMO and polarizability (α). The electronic structures as descriptors were calculated through HyperChem for Windows 7.0 using AM1 semi-empirical method. The descriptors were obtained through molecules modeling to get the most stable structure after geometry optimization step. The antimalarial activity (IC50) were taken from literature. The best model of QSAR model was determined by multiple linear regression approach and giving equation of QSAR: Log IC50 = 23.527 + 4.024 (qC4) + 273.416 (qC5) + 141.663 (qC6) – 0.567 (ELUMO) – 3.878 (EHOMO)– 2.096 (α). The equation was significant on the 95% level with statistical parameters: n = 13, r = 0.994, r2 = 0.987, SE = 0.094, Fcalc/Ftable = 11.212, and gave the PRESS = 0.348. Its means that there were only a relatively few deviations between the experimental and theoretical data of antimalarial activity.

Land surface emissivity (LSE) in the thermal infrared (TIR) is an essential parameter in the retrieving land surface temperature (LST) from space. This paper describes the LSE maps in three TIR bands (centered at 10.4, 11.2 and 12.4 µm) used for retrieving the LST from Himawari-8. Himawari-8, a next-generation geostationary satellite has high spatial and temporal resolutions compared to previous geostationary satellites. Because of these improvements, the Himawari-8 LST product is expected to contribute to the observation of small-scale environments in high-frequency. In this study, the LSE is estimated by a semi-empirical method, which is a combination of the classification based method and the normalized difference vegetation index (NDVI) thresholds method. The land cover classification information is taken from the Global Land Cover by National Mapping Organizations version3 (GLCNMO 2013). Material emissivities of soil, vegetation and others are taken from the MODIS UCSB emissivity library and the ASTER spectral library. This method basically follows the semi-empirical methods developed by the previous studies, but advanced considerations are added. These considerations are the phenology of vegetation, flooding of paddy fields, snow/ice coverage, and internal reflections (cavity effect) in urban areas. The average cavity effect on LSE in urban canopies is approximately 0.01, but it reaches 0.02 in built-up areas. The sensitivity analysis shows that the total LSE errors for the three bands are less than 0.02. The LSE estimation is especially stable at the vegetation area, where the error is less than 0.01. [ABSTRACT FROM AUTHOR]

In this work, a semi-empirical equation in terms of γ -energy, and sample density is derived, proposed, benchmarked, and applied for the peak efficiency calibration of an HPGe detector with respect to an axial source-to-detector configuration. The samples are in the form of cone-shaped Marinelli beakers of different densities in the range 0.7–1.6 g/cm 3. The method employs the experimental measurements with the ANGLE-3 software calculations using the efficiency transfer method. The peak efficiency curve of an HPGe detector is calculated using the experimental measurements of point-like sources ( 133 Ba , 137 Cs , and 60 Co). The ANGLE-3 software is then used to calculate the peak efficiency curves for samples with different densities in the γ -energy range 81–1332 keV. The peak efficiency curves are then fitted to get the energy coefficient; in addition, a linear relationship is then constructed between the energy coefficients and sample densities to get the density coefficients, and the derived equation as well. The derived equations are benchmarked using the peak efficiency curves by ANGLE-3 software in comparison with that the equation results. The results are found to be in agreement with an average relative error of about 1.5%. In addition, the derived equations are applied to estimate the activity concentration of radionuclides present in 5 cone-shaped samples with different densities using experimental measurements. The activity results are found to be in agreement with the certified values with an average relative error of about 2%. The limitation of the proposed equations is also discussed with respect to different material densities and different chemical compositions and correction factors for material composition self-attenuation for various materials are also presented. • A semi-empirical equation for HPGe peak efficiency calibration is proposed • The equations were derived using the ANGLE software calculations. • They are validated, and applied using experimental measurements. • The derived equations are simple, accurate, and time efficient. [ABSTRACT FROM AUTHOR]

We report a thorough comparison between the spin-unrestricted semi-empirical molecular orbital (SE-UMO) and density functional theory (UDFT) calculations for a variety of π-conjugated diradical molecules which exhibit through-bond magnetic exchange interactions. The spin-unrestricted neglect of diatomic differential overlap (NDDO)-based methods (UPM6 and UrPM6) and self-consistent charge density functional tight-biding (UDFTB) are examined. The UCAM-B3LYP method is used as a representative of UDFT. We have found that NDDO-based and UDFTB methods give different performances with respect to the results of UCAM-B3LYP. The degree of diradical character in the target systems decreases in the order of UPM6 > UrPM6 ≈ UCAM-B3LYP > UDFTB. The conventional UPM6 and UDFTB calculations tend to overestimate and underestimate the diradical character, respectively, whereas UrPM6 is able to provide much the same results as UCAM-B3LYP. This is convincing evidence that UrPM6 will be useful for in silico screening of materials science at much lower computational cost. [ABSTRACT FROM AUTHOR]

The objective of the present work is to study the temperature dependence of the flammability limits for pure compounds, and to develop a methodology to determine these limits in air at atmospheric pressure and at different initial temperatures of the mixture. A method to determine the lower flammability limits in those conditions was developed and compared with other methods available in the literature. The developed method shows an average absolute relative error of 3.25% and a squared correlation coefficient of 0.9928. Particularly, in the case of compounds with more than 5 carbon atoms, the method presents better accuracy than other available methods. Likewise, a method to determine the upper flammability limits was developed and compared with other widely accepted method. In this case, the developed methodology shows an average absolute relative error of 3.60% and a squared correlation coefficient of 0.9957, showing better accuracy than the available method. [ABSTRACT FROM AUTHOR]

The aim of this contribution is to investigate the inclusion of the correct exact integration limits for momentum transfer on ECPSSR theory for a wide range of elements (18≤ Z ≤92) by proton impact with energy up to 10.0 MeV and its effect on deducing a reliable semi-empirical method for calculating L shell x-ray production and ionization cross sections. A comparison is made with earlier theoretical and experimental results. [ABSTRACT FROM AUTHOR]

[Display omitted] • A series of novel FTILs were successfully synthesized and characterized. • The physicochemical properties of FTILs-water binary system were measured and discussed. • With the increase of hydrophobic alkyl side chain length of FTILs, the ion-ion interaction is stronger than ion–solvent interaction. • The FTILs are water-structure-making. • A semi-empirical method is an effective method to predict the viscosity of binary systems within a certain concentration range (m < 0.9 mol·kg−1). The application of tetramethylpiperidine 1‑oxyl (TEMPO)-based ionic liquids is a newly emerging area in the fields of the extraction natural compounds. Herein, TEMPO-based functional ionic liquids (FTILs) [C n Tr][TEMPO-OSO 3 ] (n = 2, 4, 6, 8, 10, 12, 14, 16) were synthesized and characterized by FT-IR, 1H NMR, 13C NMR and high-resolution mass spectrometry. The volumetric properties and thermodynamics of the activation for viscous flow of (FTILs + water) binary systems were measured. Under the experimental conditions, with the increase of hydrophobic side chain length, the interaction between FTILs and solvent decreases and the interaction between FTILs ions and FTILs ions increases. The FTILs are water-structure-making solutes. The activation process of the solutes for viscous flow of the binary systems is an isocoulomb reaction. A semi-empirical method is an effective method to predict the viscosity of the binary systems within a certain concentration range (m < 0.9 mol·kg−1). [ABSTRACT FROM AUTHOR]

In this paper, we perform a comprehensive study of various semi-empirical methods using publicly accessible experimental data on added resistance in waves with different ship types and conditions. Based on the analysis results, a new method (So-called "Combined method") is proposed, combining two existing methods, which are available in arbitrary wave headings. The results from the two methods are combined smoothly using a tangent hyperbolic function according to wavelengths and wave headings. The coefficients constituting the function are tuned to minimize mean squared error between predictions and model experiments. Finally, the new Combined method is verified by full-scale measurements of a general cargo ship and a container ship, and it seems to give good agreement with measurements in all analysis areas, compared to existing semi-empirical methods. Especially, it showed better performance in estimating added wave resistance at high waves, resonance frequencies, arbitrary waves, and low speeds. • Investigated semi-empirical methods for added wave resistance using experimental data • Proposed a new method of combining the two results available in arbitrary waves • Showed improvement of the new method by validation with two ships' in-service data • Performed well at high waves, resonance frequencies, arbitrary waves, and low speeds [ABSTRACT FROM AUTHOR]

A post-calculation correction is established for PM7 band gaps of transition-metal oxides. The correction is based on the charge on the metal cation of interest, as obtained fromMOPAC PM7 calculations. Application of the correction reduces the average error in the PM7 band gap from ~3 eV to ~1 eV. The residual error after correction is shown to be uncorrelated to the Hartree–Fock method upon which PM7 is based. [ABSTRACT FROM AUTHOR]

N-alkylated indanylidene pyrroline Schiff bases (NAIPs) are of great interest because their photoisomerization mimics the primary photoreactions of the retinal chromophore in rhodopsin. The nonadiabatic dynamics of two NAIP models (OMe-NAIP and dMe-OMe-NAIP) are investigated by trajectory surface-hopping method at the semi-empirical OM2/MRCI level. Both molecules show ultrafast isomerization governed by nonadiabatic dynamics via the S 0 /S 1 conical intersections (CIs). Two CIs, CI α and CI β , play important roles in the E → Z and Z → E isomerization dynamics, respectively, and are mainly distinguished by different twisting statuses of the central C1′–C4 double bond. Although both compounds show ultrafast nonadiabatic dynamics, the S 1 lifetime of dMe-OMe-NAIP is much longer than that of OMe-NAIP. By removing the methyl group, dMe-OMe-NAIP allows less twist at the C1′–C4 double bond than OMe-NAIP. This result in the slower excited-state decay of dMe-OMe-NAIP, providing solid evidence to support a similar hypothesis proposed in a previous study. [ABSTRACT FROM AUTHOR]

Organotin(IV) carboxylates with the general formula [Bu(Cl)Sn]L ( 1), (MeSn)L ( 2), and (BuSn)L ( 3) were synthesized by stirring 5-aminoisophthalic acid with KOH in methanol and with following addition of BuSnCl/MeSnCl/BuSnCl under stirring conditions. The complexes were characterized by the microanalysis, IR, and H NMR spectroscopies, mass spectrometry, and by the DFT and semi-empirical methods. The data on the elemental analysis and mass fragmentation agree well with the chemical composition of the complexes. The IR spectroscopy demonstrated a chelating coordination mode of the carboxylate group. The H NMR spectroscopy confirmed the 5-coordinated geometry of the organotin(IV) derivatives. The DFT and semi-empirical calculation of the complex 2 supported an asymmetric coordination behavior of the carboxylate group. The complexes 2 and 3 exhibited an intercalating binding with salmon sperm DNA. Significant antibacterial/antifungal potential of the complexes was confirmed by the disc diffusion method and evaluation of the minimum inhibitory concentration (MIC). The hemolytic activity of the complexes is higher than that of a free ligand and PBS and sufficiently lower than that of triton X-100. [ABSTRACT FROM AUTHOR]

Simulation of UV-VIS spectra and microscopic third-order nonlinear optical (NLO) coefficients at 532 nm wavelength of molecules based of anthocyanidin structure in gas phase environment using semi-empirical PM3 method was calculated. One-photon absorption characterizations of the investigated molecules have been theoretically obtained by configuration interaction method with doubly occupied molecular orbitals. Estimated theoretical spectra shows a sensibility to the different functional groups such as hydroxyl and methoxyl substitution in radicals. These groups causes red shift in absorption spectra in comparison to the other samples what agree well with the experimental data. Adjunction of such functional donor character group in the investigated molecule slightly decreases the HOMO-LUMO energy splitting gap but increases the ground state dipole moment resulting the substantial increase of NLO coefficient in this system comparing to the other samples. According to presented investigations the tested molecules have large nonlinear optical properties. [ABSTRACT FROM AUTHOR]

This work suggests a method for determining the activities of cylindrical radioactive samples. The self-attenuation factor was applied for providing the self-absorption correction of gamma rays in the sample material. The experimental measurement of a 238 U reference sample and the calculation using the MCNP5 code allow obtaining the semi-empirical formulae of detecting efficiencies for the gamma energies ranged from 185 to 1764 keV. These formulae were used to determine the activities of the 238 U, 226 Ra, 232 Th, 137 Cs and 40 K nuclides in the IAEA RGU-1, IAEA-434, IAEA RGTh-1, IAEA-152 and IAEA RGK-1 radioactive standards. The coincidence summing corrections for gamma rays in the 238 U and 232 Th series were applied. The activities obtained in this work were in good agreement with the reference values. [ABSTRACT FROM AUTHOR]

Copper (II) 1, 3-diphenylpropane-1, 3-dione complex and its 1, 10- phenanthroline (phen), 2, 2-bipyridine (bipy) adducts were synthesized and accordingly characterized by elemental analysis, solubility, infrared, electronic spectroscopic methods. Infrared spectral of the complex and adducts revealed that lower frequency shifts of varying magnitudes were observed in the carbonyl (C=O) and (C=C) aromatic stretching vibrations from their ligand values. Electronic spectral data indicated the geometries of the complex and adducts. The experimental vibration frequencies are compared with those obtained theoretically at semi-empirical (PM3) level of calculations. [ABSTRACT FROM AUTHOR]

Abstract: Theoretical calculation of UV–VIS spectra and second order molecular hyperpolarizability the azo-azulene derivatives was calculated. Analysis of the theoretical spectra shows a substantial sensitivity to the backside groups. The theoretically calculated absorption spectral positions are blue shifted in comparison to the experimental spectra. Adjunction of functional methyl group to the seven-membered unsaturated ring in the investigated molecule (4-aminofenilazo-1-guaiazulena) decreases the HOMO–LUMO energy splitting gap and the ground state dipole moment resulting the substantial increase of nonlinear optical (NLO) coefficient in this system comparing to the other samples. [Copyright &y& Elsevier]

The structure of the synthesized title compound is characterized by IR, UV-visible spectroscopy, and single crystal X-ray diffraction (XRD). The new compound (CHNS) crystalizes in the monoclinic P2/ c space group. In addition to the crystal structure from the X-ray experiment, the molecular geometry, vibrational frequencies, atomic charge distribution, and frontier molecular orbital (FMO) analysis of the title compound in the ground state are calculated by density functional teory (B3LYP) with 6-311G( d,p) and 6-31G( d,p) basis sets. The results of the optimized molecular structure are presented and compared with the experimental values. The computed vibrational frequencies are used to determine the types of molecular motions associated with each of the observed experimental bands. To determine the conformational flexibility, the molecular energy profile of (1) is obtained by semi-empirical (AM1) and (PM3) calculations with respect to a selected degree of torsional freedom. Moreover, molecular electrostatic potential (MEP) and thermodynamic parameters of the title compound were calculated by the theoretical methods. [ABSTRACT FROM AUTHOR]

Abstract: We have used the newly formulated analytical equivalent crystal theory method which is a modification of the ECT method to calculate the surface energies for three low-index surfaces of bcc alkali metals Li, Na, K, Rb, Cs and the bcc transition metals V, Nb, Ta, Cr, Mo, W and Fe. The data may be used as a starting point for models of surface science phenomena. The accuracy of the surface energies is established from a comparison with other theoretical results and experiment. The surface energy of each (hkl) plane in alkali metals is much lower than that in transition metals. For all bcc metals, the order of the three low-index surface energies is σ 110 < σ 111 < σ 100 in good agreement with the MEAM of Baskes [Phys. Rev. B 46 (1992) 2727] except for Cr and Mo where the ordering obtained in this work is different from that of Baskes. The calculated results show that the surface energy is anisotropic and that the closed-packed plane (110) is the lowest of the three low-index surfaces. [Copyright &y& Elsevier]