The oblique triangle configuration of three parallel screws for femoral neck fracture fixation using computer-aided design modules

Closed reduction and internal fixation with three cannulated compression screws is a common method for treating femoral neck fractures in young and middle-aged patients. Protocols including the inverted triangle configuration and dispersion of the screws still needed further supports. The purpose of this study was to explore a novel oblique triangle configuration (OTC) of three screws in fixing femoral neck fractures based on the morphology of the femoral neck isthmus (FNI). The computer-aided design modules were used to explore the ideal spatial configuration with largest triangle by three parallel screws. A univariate evaluation model was established based on the oval-like cross-section of the FNI. When the three screws were positioned by the OTC, Inverted Equilateral Triangle Configuration (IETC), and the Maximum Area Inverted Isosceles Triangle Configuration (MA-IITC) respectively, the proportion of area and circumference in the cross-section of FNI and the changing trend of proportion were compared under various torsion angles, eccentricity, and cross-sectional area of FNI. The area and circumference ratios of the parallel screws using the OTC method were significantly higher than in the IETC and MA-IITC groups. In the univariate evaluation model, the OTC area ratio and circumference ratio remained stable under the different femoral neck torsion angles, FNI cross-sectional area, and eccentricity. The OTC method provided an ideal spatial configuration for the FNA fixation with the largest area using three parallel screws. The position of the posterior screw was also away from the metaphyseal artery, potentially reducing the possibility of vascular injury and screw penetrating.

Improving Small-Molecule Force Field Parameters in Ligand Binding Studies

Small molecules are major players of many chemical processes in diverse fields, from material science to biology. They are made by a combination of carbon and heteroatoms typically organized in system-specific structures of different complexity. This peculiarity hampers the application of standard force field parameters and their in silico study by means of atomistic simulations. Here, we combine quantum-mechanics and atomistic free-energy calculations to achieve an improved parametrization of the ligand torsion angles with respect to the state-of-the-art force fields in the paradigmatic molecular binding system benzamidine/trypsin. Funnel-Metadynamics calculations with the new parameters greatly reproduced the high-resolution crystallographic ligand binding mode and allowed a more accurate description of the binding mechanism, when the ligand might assume specific conformations to cross energy barriers. Our study impacts on future drug design investigations considering that the vast majority of marketed drugs are small-molecules.

Quantum-Chemical Consideration of Al2M2 Tetranuclear Metal Clusters (M–3d-Element): Molecular/Electronic Structures and Thermodynamics

Quantum-chemical calculation of most important parameters of molecular and electronic structures of tetra-nuclear (pd) metal clusters having Al2M2 composition, where M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, or Zn (bond lengths, bond and torsion angles), and HOMO and LUMO of these compounds by means of DFT OPBE/QZVP method, have been carried out. It has been found that, for each of these metal clusters, an existence of rather large amount of structural isomers different substantially in their total energy, occurs. It has been noticed that molecular structures of metal clusters of the given type differ significantly between them in terms of geometric parameters, as well as in geometric form, wherein the most stable modifications of metal clusters considered are similar between themselves in geometric form. In addition, the standard thermodynamic parameters of formation of metal clusters considered here, and namely standard enthalpy ΔfH0(298 K), entropy Sf0(298 K), and Gibbs’ energy ΔfG0(298 K) of formation for these metal clusters, were calculated.

Cubic Octa-Carbon: Quantum-Chemical Design of Molecular Structure and Potential Way of Its Synthesis from Cubane

Quantum-chemical calculation of most important parameters of molecular and electronic structures of octa-carbon C8 having cubic form (bond lengths, bond and torsion angles) using CCSD(T)/QZVP and DFT B3PW91/QZVP methods, has been carried out. NBO analysis data and HOMO/LUMO images for this compound are presented, too. Good agreement was found between the structural data obtained using the above two quantum-chemical methods and, also, with corresponding experimental data. Also, the standard thermodynamic parameters of formation of cubic C8 considered here, and namely standard enthalpy ΔfH0(298K), entropy Sf0(298K) and Gibbs’ energy ΔfG0(298K) of formation for this compound were calculated. By using this data, a theoretically possible variant of the synthesis of this compound by dehydrogenation of cubane C8H8 is considered, and the thermodynamic characteristics of each of the four stages of this process have been calculated. It is noted that each of the four stages of this process is characterized by a very high (about 500 kJ/mol) enthalpy of activation, as a result of that, for their realization within a sufficiently short time, the use of appropriate catalysts is necessary.

A Computational Descriptor Analysis on Excited State Behaviours of a Series of TADF and Non-TADF Compounds

The thermally activated delayed fluorescence (TADF) behaviours of seventeen organic TADF emitters and two non-TADF chromophores bearing various donor and acceptor moieties were investigated, focusing on their torsion angles, singlet-triplet gap (ΔEST), spin orbit couplings (SOC) and topological ΦS index. Electronic structure calculations were performed in the framework of the Tamm-Dancoff approximation (TDA) allowing to characterize reverse intersystem crossing (RISC) probability between the S1 and T1 states. In addition, experimental ΔEST data were taken into account to choose the most appropriate functional and basis set, while absorption spectra were obtained by considering vibrational and dynamical effects through a Wigner sampling of the ground state equilibrium regions. Examining all the parameters obtained in our computational study, we rationalized the influence of electron-donating and electron-accepting groups and the effects of geometrical factors, namely torsion angles, on a wide class of diverse compounds ultimately providing an easy and computationally effective protocol to assess TADF efficiencies.

Design and Analysis of a Laminated Composite Tube

Piping is an important material for fluid transportation in modern industry, and well-structured piping can reduce losses due to maintenance and replacement downtime. Therefore it is necessary to design and analyze the pipes in order to optimize their structure. This paper focuses on composite laminated pipes. In this design case, the structural analysis of this pipe will be carried out by applying the laminate theory, and the structural analysis model will be established by using Mathcad software. The stress and strain of each laminate will be calculated by entering the winding angle and the corresponding equations in this software. The final optimal winding Angle can be determined by verifying the winding angles that can be maintained under maximum stress failure criteria using Mathcad contours and detailed tables of winding and torsion angles.

UoC-6: a first MOF based on a perfluorinated trimesate ligand

Reaction of Sc(NO3)3·5H2O with K(H2 pF-BTC) – the monopotassium salt of perfluorinated trimesic acid – led to the formation of single crystals of [ Sc ( p F − BTC ) ( H 2 O ) 3 ] ∞ 1 ⋅ 4 H 2 O ${}_{\infty }{}^{1}[\text{Sc}(pF-\text{BTC}){({\text{H}}_{2}\text{O})}_{3}]\cdot 4{\text{H}}_{2}\text{O}$ ( P 1 ‾ $P‾{1}$ , Z = 2). DTA/TGA measurements revealed that all water molecules were released below 200 °C. Using powder synchrotron radiation diffraction data, the crystal structure of the residue of the dehydration was elucidated and the results confirmed the formula [ Sc ( p F − BTC ) ] ∞ 3 ${}_{\infty }{}^{3}[\text{Sc}(pF-\text{BTC})]$ (Fddd, Z = 16). The compound is similar, but not isostructural to the recently published UoC-4 (I41/amd, Z = 8; UoC: University of Cologne) with a difluorinated trimesate (dF-BTC3–) as connecting linker. Both compounds can be classified as metal-organic frameworks (MOFs) consisting of a 3D network of Sc3+ nodes connected by the fluorinated trimesate ligands. They contain small pores, but their opening windows are too small for any guest molecules to pass. Remarkably, UoC-4 with a lower symmetric ligand (dF-BTC3–) crystallizes in a higher symmetry space group (I41/amd) than UoC-6 (Fddd). This can be rationalized by increasing torsion angles of the carboxylate moieties in the pF-BTC3– ligand.

Photophysical Properties of Benzophenone Based TADF Emitters in Relation to Their Molecular Structure

Thermally activated delayed fluorescence (TADF) materials are commonly used in various apparatus, including organic light emitting device (OLED)-based displays, as they remarkably improve the internal quantum efficiencies (IQE). Alt-hough there is a wide range of donor-acceptor based compounds possessing TADF properties, in this computational study we investigated TADF and some non-TADF chromophores, containing benzophenone or its structural derivatives as the acceptor core, together with various donor moieties. Following the computational modeling of the emitters, several excited state properties, such as the absorption spectra, singlet-triplet energy gaps (∆EST), natural transition orbitals (NTO) and the topological ΦS indices, have been computed. Along with the donor-acceptor torsion angles and spin-orbit coupling (SOC) values, these descriptors have been utilized to investigate potential TADF efficiency. Our study has shown that on the one hand, our photophysical/structural descriptors and computational methodologies predict the experi-mental results quite well, on the other hand, our extensive benchmark can be useful to pinpoint the most promising func-tionals and descriptors for the study of benzophenone based TADF emitters.

Effect of the THF molecules on the hydrate cavities formation with adding NaCL molecules into the modeling system

In this work, using molecular dynamics methods by Gromacs package we simulate the hydrate formation in systems containing THF, water, and NACL molecules at different thermodynamic conditions and concentration of THF molecules. The curves of the number of hydrogen bonds are obtained depending on the simulation time at different temperatures. The computer simulations results show that the hydrogen bonds between THF and water molecules are relatively weak, with a maximum number of two water molecules hydrogen bonded to THF, but THF can facilitate water molecules rearrangement to form a pentagonal or hexagonal planar ring that is the part of clathrate cavity. In addition, the THF molecule can significantly increase the likelihood to form clathrate cavities suitable for the second guest molecule. The effect of THF molecules concentration on the hydrate cavities formation with adding NaCL molecules into the modeling system is shown. In this work, data are obtained on the magnitude of torsion angles, the percentage of which increases depending on the simulation time, which allows concluding that labile large and small cavities of sII hydrates are formed. The increase in the THF molecules concentration is shown to lead to a decrease in the hydrogen bonds number of water molecules in the simulated system.

Understanding the Origin of Structural Diversity of DNA Double Helix

Deciphering the contribution of DNA subunits to the variability of its 3D structure represents an important step toward the elucidation of DNA functions at the atomic level. In the pursuit of that goal, our previous studies revealed that the essential conformational characteristics of the most populated “canonic” BI and AI conformational families of Watson–Crick duplexes, including the sequence dependence of their 3D structure, preexist in the local energy minima of the elemental single-chain fragments, deoxydinucleoside monophosphates (dDMPs). Those computations have uncovered important sequence-dependent regularity in the superposition of neighbor bases. The present work expands our studies to new minimal fragments of DNA with Watson–Crick nucleoside pairs that differ from canonic families in the torsion angles of the sugar-phosphate backbone (SPB). To address this objective, computations have been performed on dDMPs, cdDMPs (complementary dDMPs), and minimal fragments of SPBs of respective systems by using methods of molecular and quantum mechanics. These computations reveal that the conformations of dDMPs and cdDMPs having torsion angles of SPB corresponding to the local energy minima of separate minimal units of SPB exhibit sequence-dependent characteristics representative of canonic families. In contrast, conformations of dDMP and cdDMP with SPB torsions being far from the local minima of separate SPB units exhibit more complex sequence dependence.