Interaction energy and decomposition of interaction energy of halo-substituted phthalimide with carbon nanotube

Interaction energy of phthalimide (ph) with carbon nanotube (CNT) calculated at SAPT0 level with a mixed basis set (6-31G* for CNT and 6-311G* for ph) is -19.51 kcal/mol. Halosubstitution of the phthalimide generally strengthens its interaction with the CNT and interaction energies are in the range from -21.02 kcal/mol to -22.62 kcal/mol going from ph-Cl to ph-I. However, interaction energy for phthalimide substituted with F atom (ph-F) is weaker (-18.81 kcal/mol) than for non-substituted phthalimide. For ph-Cl, ph-Br, ph-I, the total interaction energy increases with the higher halogen atomic number, because of the significant dispersion term and, less pronounced, electrostatic term increase. The smallest dispersion is calculated for ph-F/CNT (-28.72 kcal/mol), while the remaining systems range from -31.51 kcal/mol for ph/CNT to -35.78 kcal/mol for ph-I/CNT. Apart from dispersion, the system with fluorine has a less pronounced electrostatic term than other substituted phthalimides and does not follow trends observed for other systems

Influence of phthalimide substitution on the interaction with carbon nanotube

The interaction energy of phthalimide and carbon nanotube calculated at SAPT0/6- 31G* level is -17.37 kcal/mol. After the substitution of phthalimide with a hydroxyl group interaction was stronger (-18.64 kcal/mol) because of the larger dispersion followed by an increase in the molecular planar surface and an increased electrostatic term due to the additional electronegative oxygen atom. When a hexafluoroisopropyl group is used as a substituent (ph6F/CNT), the molecule loses planarity and the dispersion term only slightly increases, but not enough to compensate for the unfavorable shift in the exchange interaction contribution. Thus, the resulting interaction energy in the ph-6F/CNT system is weaker (16.63 kcal/mol) than in the original ph/CNT system. Electrostatic contributions are also significant, with the largest value calculated for ph-OH/CNT (11.32 kcal/mol), because of the additional electronegative oxygen atom in the hydroxyl group. The other two systems, ph/CNT and ph-6F/CNT have electrostatic interactions of 10.14 and 10.05 kcal/mol, respectively. Exchange interaction is more repulsive for ph-OH (+26.60 kcal/mol) and ph-6F (+26.29 kcal/mol) systems than the ph/CNT (+24.86 kcal/mol)

The importance of the metal ion and complex geometry on the interaction between a coordinated amino acid and a free water molecule

Using quantum chemistry calculations and analysis of crystal structures from the Cambridge Structural Database (CSD), three types of hydrogen bonds, NH/O, O1/HO (hydrogen bond of a coordinated oxygen atom), and O2/HO (hydrogen bond of a noncoordinated oxygen atom) between different metal ion complexes of amino acids and a free water molecule were studied. Octahedral cobalt(III) [1] and nickel(II), square pyramidal copper(II), square planar copper(II), palladium(II), and platinum(II) complexes were investigated at M06L-GD3/def2-TZVPP level, and interaction energies were calculated using basis set superposition error (BSSE) corrected values. The NH/O hydrogen bond of a doubly positive complex has an interaction energy of -16.9 kcal/mol. For singly positive complexes, NH/O hydrogen bonds are weaker, from -8.3 to -12.1 kcal/mol strong, while for neutral complexes their values are the weakest, from -5.2 to - 7.2 kcal/mol. In neutral complexes with O1/HO, interaction energies are from -2.2 to - 5.1 kcal/mol, while interactions in singly negatively charged complexes are stronger, from -6.9 to 8.2 kcal/mol. Neutral complexes also have weaker O2/HO hydrogen bonds, from -3.7 to -5.0 kcal/mol, than the singly negatively charged systems, which have interaction energy values from -8.0 to -9.0 kcal/mol. Therefore, the results of quantum chemistry calculations showed that the strongest hydrogen bond is the NH/O, followed by O1/HO, and lastly, O2/HO interaction. The results also show a strong influence of the complex charge on the interaction energy. Other factors that influence the interaction energy to a smaller extent are metal oxidation number, coordination number, and metal atomic number. In the crystal structures from the CSD search, the d distributions for copper(II) and cobalt(III) amino acid complexes are in good agreement with the quantum chemistry results

Computational and crystallographic study of hydrogen bonds in the second coordination sphere of chelated amino acids with a free water molecule: Influence of complex charge and metal ion

Hydrogen bonds of glycine complexes were calculated using quantum chemistry calculations at M06L-GD3/def2-TZVPP level and by analyzing the crystal structures from the Cambridge Structural Database (CSD). One hydrogen bond where amino acid plays the role of the H-donor (NH/O), and two where it plays the role of the H-acceptor (O1/HO, O1 is a coordinated oxygen atom, and, O2/HO, O2 is a non-coordinated oxygen atom) were investigated. The calculations were done on octahedral nickel(II), square pyramidal copper(II), square planar copper(II), palladium(II), and platinum(II) glycine complexes with different charges adjusted using water(s) and/or chlorine ion(s) as the remaining ligands. For NH/O hydrogen bond, interaction energies of neutral complexes are the weakest, from -5.2 to -7.2 kcal/mol for neutral, stronger for singly positive, from -8.3 to -12.1 kcal/mol, and the strongest for doubly positive complex, -16.9 kcal/mol. For O1/HO and O2/HO interactions, neutral complexes have weaker interaction energies (from -2.2 to -5.1 kcal/mol for O1/HO, and from -3.7 to -5.0 kcal/mol for O2/HO), than for singly negative complexes (from -6.9 to -8.2 kcal/mol for O1/HO, and from -8.0 to -9.0 kcal/mol for O2/HO). Additionally to the complex charge, metal oxidation number, coordination number, and metal atomic number also influence the hydrogen bond strength, however, the influence is smaller.This is the peer-reviewed version of the article: Zrilić, S. S., Živković, J.,& Zarić, S.. (2023). Computational and crystallographic study of hydrogen bonds in the second coordination sphere of chelated amino acids with a free water molecule: Influence of complex charge and metal ion. in Journal of Inorganic Biochemistry Elsevier., 251. [https://doi.org/10.1016/j.jinorgbio.2023.112442

Ventilatory capacity in soy bean workers

Ventilacijska funkcija ispitivana je u 27 radnika izloženih prašini soje nakon ekstrakcije ulja. Prevalencija svih kroničnih respiratornih simptoma bila je viša u eksponiranih nego u kontrolnih radnika, premda razlike nisu bile statistički značajne. Tijekom radne smjene ponedjeljkom utvrđene su statistički značajne akutne redukcije za maksimalni ekspiratorni protok pri 50% i 25% vitalnog kapaciteta (FEF50: -6,4%; FEF25: - 12,4%). Promjene u vitalnom kapacitetu (FVK: -3,6%) i forsiranom ekspiratornom volumenu u prvoj sekundi (FEV1: -2, 7%) bile su manje, ali još uvijek statistički značajne. Analiza rezultata testiranja ventilacijskih kapaciteta ponedjeljkom prije smjene u radnika na preradi soje upućuje na to da eskpozicija prašini soje u nekih radnika može dovesti do pojave kroničnog oštećenja respiratornog sustava.Ventilatory capacity was examined in a group of 29 workers exposed to soy bean dust. The prevalence of all chronic respiratory symptoms was higher in the exposed than in control workers, although the differences were not statistically significant. During the Monday work shift there was a significant mean acute across-shift decrease in maximum expiratory flow rates at 50% and 25% vital capacity (FEF50: -6.4%; FEF25: -12.4%). Changes in forced vital capacity (FVC: -3.6%) and in one-second forced expiratory volume (FEV1: -2. 7%) were smaller, but statistically significant. Analysis of Monday preshift values of ventilatory capacity in soy bean workers suggests that exposure to soy bean dust may lead to chronic respiratory impairment in some workers

Hydrogen bonds of a water molecule in the second coordination sphere of amino acid metal complexes: Influence of amino acid coordination

The hydrogen bonds of free and coordinated amino acids with water molecule were studied by analyzing data in the crystal structures from the Cambridge Structural Database (CSD) and by quantum chemical calculations. The CSD data indicate bifurcated NH/O hydrogen bonds and O1/HO hydrogen bonds of coordinated oxygen. The O/HO hydrogen bonds of free zwitterions and non-coordinated carbonyl oxygen (O2/HO) in metal complexes form primarily linear, non-bifurcated hydrogen bonds. Calculated M06L-GD3/def2-TZVPP interaction energies for free zwitterions (glycine, cysteine, phenylalanine and, serine) and water molecule are in the range from −5.1 to −9.6 kcal/mol for NH/O and from −6.9 to −7.6 kcal/mol for O/HO interactions. Coordinated amino acids in neutral octahedral cobalt(III) complexes have NH/O interaction energies ca. -7.4 kcal/mol, independent of the amino acid. The singly and doubly charged complexes have stronger NH/O interactions; the strongest has energy of −16.9 kcal/mol. In the case of O1/HO hydrogen bond, the interaction energy decreases upon coordination; interactions are quite weak for neutral complexes (−2.2 to −2.6 kcal/mol). For O2/HO hydrogen bonds, all amino acids except serine show slightly stronger interaction in singly negative complexes (−6.3 to −8.0 kcal/mol), while interactions are weaker for neutral complexes (−2.8 to −4.4 kcal/mol), comparing to zwitterions

A Charge-Balancing Incremental Analog to Digital Converter for Instrumental Applications

International Telemetering Conference Proceedings / October 17-20, 1988 / Riviera Hotel, Las Vegas, NevadaA switched-capacitor technique for realization of one bit serial A/D converter is presented. A conversion accuracy that is higher than 15 bits can be expected from its integrated realization. Results of simulation are presented. It is shown that arithmetic operations on bit serial signals are possible. Using arithmetic operations on delta-modulated signals, it is possible to build inexpensive options necessary in instrumentation.International Foundation for TelemeteringProceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit http://www.telemetry.org/index.php/contact-us if you have questions about items in this collection

Pasoš zavarivača – razvoj

EUREKA project E! 2774 FACTORY WELDERS' PASSPORT, Engh E. (project manager), et al. On-line software database system, a harmonisation of EWF (European Welders Federation) skills and training certificates that allows for the accreditation of welding related personnel, wherever they work in Europe

Isopiestic Determination of the Osmotic and Activity Coefficients of K2HPO4(aq), Including Saturated and Supersaturated Solutions, at T=298.15 K

The osmotic coefficients of K2HPO4(aq) have been measured at T=298.15 K by the isopiestic vapor pressure method over the range of molalities from 1.3846 mola lt ...kg(-1) to 13.939 mola lt ...kg(-1) (oversaturation) with CaCl2(aq) as the reference solution. The molalities and osmotic coefficients of saturated solutions in equilibrium with K(2)HPO(4)a lt ...xH(2)O(cr) were measured simultaneously by the same method. Available literature osmotic coefficients of K2HPO4(aq) at T=298.15 K, and our new experimental data, were combined and modeled using an extended form of Pitzer's equation and the Clegg-Pitzer-Brimblecombe equation based on the mole-fraction-composition scale. These equations were used to calculate the activity coefficients of K2HPO4(aq) at T=298.15 K

Isopiestic determination of the osmotic and activity coefficients of the {yKCl + (1-y)K2HPO4}(aq) system at T=298.15 K

The osmotic coefficients of aqueous mixtures of KCl and K2HPO4 have been measured at T = (298.15 +/- 0.01) K by the isopiestic vapor pressure method over the range of ionic strengths from (2.3700 to 11.250) mol . kg(-1) using CaCl2(aq) as the reference solution. Our new experimental results were modeled with an extended form of Pitzer's ion-interaction model equations, both with the usual mixing terms and with Scatchard's neutral-electrolyte mixing terms, and with the Clegg-Pitzer-Brimblecombe equations based on the mole-fraction-composition scale. There is a dearth of previously published isopiestic data for mixtures containing salts of HPO42- (aq) and, consequently, no previous measurements are available for comparison with the present results. The present study yields Cl--HPO42- mixing parameters for these three models that are needed for modeling the thermodynamic activities of solute components of natural waters and other complex aqueous electrolyte mixtures