Analysis Of Density Distribution Research Articles

Fabrication of pebble stone-like PbMoO4 nanostructure: Focus on photocatalysis, photoluminescence and electron density distribution analysis

In this work, the PbMoO4 nanocatalyst is synthesized by the hydrothermal way. The as-prepared PbMoO4 nanomaterial was confirmed by powder X-ray diffraction (P-XRD), UV–visible diffuse reflectance spectroscopy (UV-DRS), photoluminescence (PL), scanning electron microscopy (SEM) and Transmission electron microscopy techniques (TEM). The scanning Electron Microscope result indicates the pebble stone morphology structure of PbMoO4 nanomaterials. The catalytic performance for as-synthesized PbMoO4 nanomaterial was analyzed by the ciprofloxacin (CIP) degradation process. More interestingly, the as-prepared PbMoO4 material is having higher catalytic performance compared to the other previous PbMoO4 nanoparticles reports with an efficiency of above 92%. A photodegradation mechanism and the reaction kinetics of PbMoO4 nanomaterial were also investigated. The aforesaid results are strong enough to suggest the PbMoO4 nanomaterial may be an effective catalyst for environmental application. In addition, the electron density distributions studies were carried out for this PbMoO4 nanomaterial to explain the bond length value between the atoms.

A Standardized Analysis of Tertiary Lymphoid Structures in Human Melanoma: Disease Progression- and Tumor Site-Associated Changes With Germinal Center Alteration.

There is increasing evidence that tertiary lymphoid structures (TLS) control not only local adaptive B cell responses at melanoma tumor sites but also the cellular composition and function of other immune cells. In human melanoma, however, a comprehensive analysis of TLS phenotypes, density and spatial distribution at different disease stages is lacking. Here we used 7-color multiplex immunostaining of whole tissue sections from 103 human melanoma samples to characterize TLS phenotypes along the expression of established TLS-defining molecular and cellular components. TLS density and spatial distribution were determined by referring TLS counts to the tissue area within defined intra- and extratumoral perimeters around the invasive tumor front. We show that only a subgroup of primary human melanomas contains TLS. These TLS rarely formed germinal centers and mostly located intratumorally within 1 mm distance to the invasive tumor front. In contrast, melanoma metastases had a significantly increased density of secondary follicular TLS. They appeared preferentially in stromal areas within an extratumoral 1 mm distance to the invasive tumor front and their density varied over time and site of metastasis. Interestingly, secondary follicular TLS in melanoma often lacked BCL6+ lymphatic cells and canonical germinal center polarity with the formation of dark and light zone areas. Our work provides an integrated qualitative, quantitative and spatial analysis of TLS in human melanoma and shows disease progression- and site-associated changes in TLS phenotypes, density and spatial distribution. The frequent absence of canonical germinal center polarity in melanoma TLS highlights the induction of TLS maturation as a potential additive to future immunotherapy studies. Given the variable evaluation strategies used in previous TLS studies of human tumors, an important asset of this study is the standardized quantitative evaluation approach that provides a high degree of reproducibility.

Multiobjective Design Optimization of Stator for Synchronous Generator Using Bat Algorithm and Analysis of Magnetic Flux Density Distribution

— In this study, we aimed to optimize 3000 kVA synchronous generator (SG) stator design to obtain the desired magnetic flux density distribution and efficiency. We used Maxwell simulations for experiments on some design parameters of stator (slot height and teeth width). Then second-order regression models are calculated that represent the relations between the factors (design parameters) and the measured performance criteria (called as the responses: stator-teeth flux density, stator-yoke flux density, and efficiency). These regression models are used at the multiobjective optimization phase. Bat algorithm (BA) is used for performing the multiobjective optimization. By combining Maxwell with regression modeling and BA, the efficiency of the SG is increased to 96.84% from 96.5% with a more acceptable magnetic flux density (between 1.65 and 1.70 T ranges). The stator-teeth flux density and stator-yoke flux density are calculated as 1.9 T and 2.07 T for the current SG, whereas these values are reduced to 1.647 and 1,634 T, respectively, for the optimized SG. Results of this study show how the numerical simulation can be successfully combined with the BA to improve the efficiency of the SG by providing the desired magnetic flux density distribution.

Tris-{Hydridotris(1-pyrazolyl)borato}lanthanide Complexes: Synthesis, Spectroscopy, Crystal Structure and Bonding Properties

Complexes of trivalent lanthanides (Ln) with the hydridotris(1-pyrazolyl)borato (Tp) ligand Ln[η3-HB(N2C3H3)3]3 (LnTp3) were subjected to a joint experimental–theoretical analysis. X-ray diffraction experiments have been performed on CeTp3, NdTp3, SmTp3, GdTp3, and TbTp3 in the nine-fold coordination and on DyTp3, HoTp3, ErTp3, TmTp3, YbTp3, and LuTp3 in the eight-fold coordination form. Density functional theory (DFT) calculations were carried out for all 15 LnTp3 complexes. They extended the X-ray diffraction data available on the LnTp3 compounds and facilitated a straightforward interpretation of trends in the structural parameters. As a result of the joint analysis, significant steric strain in the equatorial coordination sites of the nine-coordinate structures was recognized. Trends in the bonding properties were elucidated by energy decomposition and quantum theory of atoms in molecules (QTAIM) analysis of the electron density distribution. These results revealed the major electrostatic character of the Ln…Tp bonding and fine variation of charge transfer effects across the Ln row.

Effect of electrode wire surface integrity and surface oxides on the stability of gas metal arc welding

ABSTRACT ER70S-6 gas metal arc welding (GMAW) wire electrodes are widely used in various market segments. Stability of GMAW process is vital for obtaining desired welding performance. The random variations in voltage transients can represent welding consumable quality. In the present study, wire electrodes from three sources were analysed in standard synergic and pulse synergic GMAW using digital storage oscilloscope (DSO) and high-speed camera setup. The recorded voltage data were analysed using time domain and probability density distribution (PDD) analysis. High speed camera images were used to understand abnormal voltage variations observed in voltage oscillograms and PDD patterns. Results confirmed the presence of signatures of wire quality in the variations of analysed voltage transients along with high speed camera images. Microscopic examination confirmed damaged wire surface and presence of remnant oxide layer post manufacturing on the wire surface/sub surface as the main reasons for poor product performance and arc instability. The method adopted in this work can help end users in selecting appropriate welding wire to enhance productivity and can also help wire manufacturers to improve their product quality.

Monoprotonated Dimethyl Sulfoxide, [HOSMe2]+: Synthesis, Crystal Structure, Spectroscopic and Theoretical Studies of [HOSMe2]2[OsCl6] ⋅ 2H2O

AbstractComplex [H(dmso)]2[OsIVCl6] ⋅ 2H2O (1) was synthesized by refluxing of [H(dmso)2]2[OsCl6] in concentrated HCl and characterized by the IR and UV/Vis spectroscopy and X‐ray powder and single‐crystal diffraction studies. In this complex, rare highly electrophilic [Me2S=O⋅⋅⋅H]+ cation is stabilized by multiple chalcogen bonds including bifurcated S⋅⋅⋅(Cl)3 and S⋅⋅⋅Cl non‐covalent interactions. DFT calculations and topological analysis of the electron density distribution within the formalism of Bader's theory (QTAIM method) support the presence of intermolecular non‐covalent interactions S⋅⋅⋅Cl and O⋅⋅⋅Cl in the solid state.

Investigation of Lithium Transport in 3D Porous Solid-State Li-Ion Electrolytes

All-solid-state batteries (ASSB) are candidates for the next generation of high power- and energy storage systems. To reach their full potential, limiting factors like high interfacial resistances or decomposition of the electrolyte require further understanding and optimization. Porous 3D electrolyte networks, like the oxidic trilayer structures prepared by the authors, provide a much higher specific contact area between the electrolyte and the active materials [1]. The fabrication via a tape casting process allows for control of the porosity and sample thickness and is scalable to industrial production levels [2]. It was demonstrated that such a system allows for much higher current densities compared to a planar setup. Nevertheless, the critical influences of grain and grain boundaries on the cell performance and the lithium transport in these porous oxidic systems are still under investigation and not fully resolved.In this contribution, we investigate the lithium transport in porous garnet-type 3D electrolyte network consisting of Li7La2.75Ca0.25Zr1.75Nb0.25O12. The focus of our study is on the influence of grain and grain boundary effects. Our multi-scale approach consists of 3D microstructure-resolved simulations, which are supplemented by a thermodynamically consistent modeling framework [3,4]. The modeling framework enables us to provide additional microscopic interface- and bulk properties such as space charge layer effects, which are transferred as theory-based input parameters to our 3D microstructure-resolved simulations.The 3D simulations are performed directly on virtual microstructures reconstructed from FIB-SEM tomography measurements. In our study, we investigate samples with different porosity, thereby, our approach inherently incorporates the morphological features of the porous solid electrolyte. Moreover, we perform impedance simulations on the porous polycrystalline 3D electrolyte network. The simulations reproduce the experimental data and allow us to identify features in the corresponding impedance spectra. This approach enables us to analyze the correlation between grain size and garnet porosity on the cell impedance.In the final step, we virtually fill the porous electrolyte networks with metallic lithium corresponding to different state of charges during operation. Based on the impedance analysis, we evaluate the area specific resistance in our simulations and validate the results against experimental data. The current density distribution analysis allows identifying flux hot spots, which can serve as an indicator for dendrite growth [5]. The comparison between simulations and experiments demonstrates the importance of interfacial processes at the grain boundaries and gives directions for optimizing future oxide-based ASSBs. Acknowledgment This work was conducted as part of the US-German joint collaboration on "Interfaces and Interphases In Rechargeable Li-metal based Batteries” supported by the US Department of Energy (DOE) and German Federal Ministry of Education and Research (BMBF). Financial support was provided by BMBF under grant number 03XP0223E and DOE under grant number DEEE0008858. Reference s : [1] T. Hamann et al., Adv. Funct. Mater. 30 (2020) 1910362. [2] T. Hitz et al., Materials Today 22 (2019) 50-57. [3] A. Latz and J. Zausch, J. Power Sources 196 (2011) 3296-3302. [4] S. Braun et al., J. Phys. Chem. C 119 (2015) 22281-22288. [5] C.Tsai et al., ACS Appl. Mater. Interfaces 8 (2016) 10617-10626.

Effect of Current Density Distribution in the Zinc Plating Process

This paper presents an analysis of the current density distribution in the zinc plating process, using a two-dimension approach. The simulation presents a model based on COMSOL Multi-physics software. The simulation neglected the effect of mass transfer and production of gaseous species, in order to simplify the resolution. Additionally, a validation from the simulation through a comparison with the experimental data at similar conditions was performed. The results presented a good agreement between the experimental and simulated data. The graphics from both approaches showed a decreasing trend in the current density along the cathode length. This trend arises from the electrons movement in the electrodes; electrons flow through the least resistive path. Given the fact that zinc electroplating incurs an important industrial application, simulation is becoming a promising way to optimization and improvement.

Azoimidazole gold(III) complexes: Synthesis, structural characterization and self-assembly in the solid state

Preparation of novel triarylazoimidazole trichlorogold(III) complexes is described. The new compounds were characterized using C, H, N elemental analyses, IR, UV/Vis and X-ray diffraction analysis. Structural characterization revealed that the distances N(imidazolic)···Au (2.030 Å (4) and 2.037 Å (5)) are significantly shorter than N(azo group)···Au (2.853 Å (4) and 2.899 Å (5)) indicating that the azo group is rather weakly coordinated at the Au(III) metal center. Thus, triarylazoimidazole trichlorogold(III) complexes could be described as square planar gold(III) complexes with weakly binding to the gold(III) center azogroup. Non-covalent chlorine···chlorine interactions were detected for 5 in the solid state and studied by DFT calculations and topological analysis of the electron density distribution within the framework of Bader’s theory (QTAIM method). Theoretical studies demonstrated that short non-covalent Cl···Cl interactions (3.202 Å) play crucial role in self-assembly of high-valent Au(III) chloride.

Attractive fluorine···fluorine interactions between perfluorinated alkyl chains: a case of perfluorinated Cu(II) diiminate Cu[C2F5–C(NH)–CF=C(NH)–CF3]2

Abstract A synthesis of the perfluorinated copper diiminate complex Cu[C2F5–C(NH)–CF=C(NH)–CF3]2 (3) and its self-assembly into infinite 1D chains in the crystal via Type II C(sp3)–F···F–C(sp3) contacts between perfluoroethyl substituents is reported. Rare Type II F···F interactions were studied by DFT calculations and topological analysis of the electron density distribution within the formalism of Bader’s theory (QTAIM method). This is the first report which discusses Type II contacts between perfuoroalkyl chains.

Bone Density Micro-CT Assessment during Embedding of the Innovative Multi-Spiked Connecting Scaffold in Periarticular Bone to Elaborate a Validated Numerical Model for Designing Biomimetic Fixation of Resurfacing Endoprostheses.

Our team has been working for some time on designing a new kind of biomimetic fixation of resurfacing endoprostheses, in which the innovative multi-spiked connecting scaffold (MSC-Scaffold) that mimics the natural interface between articular cartilage and periarticular trabecular bone in human joints is the crucial element. This work aimed to develop a numerical model enabling the design of the considered joint replacement implant that would reflect the mechanics of interacting biomaterials. Thus, quantitative micro-CT analysis of density distribution in bone material during the embedding of MSC-Scaffold in periarticular bone was applied. The performed numerical studies and corresponding mechanical tests revealed, under the embedded MSC-Scaffold, the bone material densification affecting its mechanical properties. On the basis of these findings, the built numerical model was modified by applying a simulated insert of densified bone material. This modification led to a strong correlation between the re-simulation and experimental results (FVU = 0.02). The biomimetism of the MSC-Scaffold prototype that provided physiological load transfer from implant to bone was confirmed based on the Huber–von Mises–Hencky (HMH) stress maps obtained with the validated finite element (FE) model of the problem. The micro-CT bone density assessment performed during the embedding of the MSC-Scaffold prototype in periarticular bone provides insight into the mechanical behaviour of the investigated implant-bone system and validates the numerical model that can be used for the design of material and geometric features of a new kind of resurfacing endoprostheses fixation.

Supramolecular organic frameworks derived from bromoaryl-substituted dichlorodiazabutadienes via Cl···Br halogen bonding

1-Aryl-3-(4-bromophenyl)-4,4-dichloro-1,2-diazabuta-1,3- dienes were synthesized via copper-catalyzed reaction of 4-bromobenzaldehyde arylhydrazones with CCl4. X-ray diffraction analysis revealed non-covalent Cl···Br interactions in the crystalline state and formation of 3D supramolecular framework; DFT calculations and topological analysis of the electron density distribution within the framework of Bader's theory (QTAIM method) confirmed these observations. Theoretical calculations showed that highly polarizable dichlorodiazadiene unit is capable of acting as a relatively strong halogen bond donor.

First-principles study of formation and performance of diamond (111)/Al interface

The simple and convenient metallic mask method is a significant method of preparing diamond nanostructures. The metallic mask method has poor repeatability and can not give the ideal results, because it is supported by no theory about formation of surface mental nanoparticles and its technological parameters are optimized by no experimental techniques that are expensive either. Aiming at the formation and performance of the diamond/Al interface, this paper adopts the first-principles to study the adsorption and migration behavior of Al atoms on the H-terminated diamond surface and the structure of the diamond/Al interface. The results show that the highest adsorption energy is at the T4 position, which is only 0.181 eV, through comparing the adsorption energies of Al atoms at the highly symmetrical positions (Top, Br, H3 and T4) on the surface of the H-terminated diamond (111). The adsorption energies at these different positions are similar and the maximum difference is only 0.019 eV. There is formed no chemical bond, although Al has partial charge transfer on the H-terminated surface through the analysis of differential charge density and worse layout distribution. This phenomenon can be considered as electrostatic adsorption. That is to say, the adsorption of Al atoms are physical adsorption. The smooth potential energy surface also makes it easier for Al atoms to migrate on the diamond surface. The calculation results reveal that the migration activation energies of the two possible migration paths (from T4 position to Br position and from T4 to Top position) are 0.011 eV and 0.026 eV respectively. The above results imply that the metal Al and diamond are mainly connected by weak force, so the adhesion work of the three diamond/Al interface structures is compared based on the geometric stacking structure. The results show that the adhesion work of the three interfaces is around 0. These results indicate that the stability of the diamond/Al interface is not high and the stable structure of the interface is easily destroyed when the external environment changes. This speculation can be confirmed in molecular dynamics. When the simulated temperature is 300 ℃, the liquefied metal Al obviously accumulates into spheres. According to the above research results, we deduce that the metallic mask method does not require high requirements for the relationship between the metal and the substrate material, which depends mainly on the surface topography of the base material. This research provides an important theoretical reference for understanding the formation mechanism of metal nanomasks.

Identification of supramolecular dimers in the crystal structure of (Z)-1-(((5-fluoropyridin-2-yl)amino)methylene)naphthalen-2(1H)-one via C(sp2)—H⋯F hydrogen bonding: A combined experimental and theoretical study

Title compound C16H11FN2O (1) is nearly planar, and adopts the keto-amine form with a strong intramolecular N—H⋯O hydrogen bond. Interestingly, the compound features an intramole­cular C—H⋯N weak interaction in the crystal. In addition, the molecules of 1 form supra­molecular dimers via C—F⋯H—C13 weak interactions. The nature and energies of intermolecular noncovalent interactions, which are responsible for the supramolecular dimerization, are studied theoretically using DFT calculations, and the topological analysis of the electron density distribution is performed within the formalism of Bader's theory (QTAIM method).

A theoretical study on novel neutral noble gas compound F4XeOsF4.

A noble gas compound containing a triple bond between xenon and transition metal Os (i.e. F4XeOsF4, isomer A) was predicted using quantum-chemical calculations. At the MP2 level of theory, the predicted Xe-Os bond length (2.407 Å) is between the standard double (2.51 Å) and triple (2.31 Å) bond lengths. Natural bond orbital analysis indicates that the Xe-Os triple bond consists of one σ-bond and two π-bonds, a conclusion also supported by atoms in molecules (AIM) quantum theory, the electron density distribution (EDD) and electron localization function (ELF) analysis. The two-body (XeF4 and OsF4) dissociation energy barrier of F4XeOsF4 is 15.6 kcal mol-1. The other three isomers of F4XeOsF4 were also investigated; isomer B contains a Xe-Os single bond and isomers C and D contain Xe-Os double bonds. The configurations of isomers A, B, C and D can be transformed into each other.

Effect of preparation techniques on BaWO4: structural, morphological, optical and electron density distribution analysis

The scheelite BaWO4 materials were prepared by co-precipitation and molten salt method. The crystallographic structure, optical behavior, morphology, and electronic charge distributions of the prepared BaWO4 were studied by various spectroscopic techniques such as X-ray power diffraction, photoluminescence spectroscopy, UV–Visible absorption spectroscopy, scanning electron microscopy and electron density distribution analysis, respectively. The micron-sized rock-like structured BaWO4 particles were obtained in the surface morphology. These structured BaWO4 exhibited intense blue emission peak at 430 nm when excited at 375 nm. The synthesized material revealed the high intense blue emission which attributed to the intrinsic transitions of [WO4]2− tetrahedrons.

Application of Electronic Density Distribution Analysis in Organic Chemistry Teaching for Developing Organic Chemistry Thinking

Application of Electronic Density Distribution Analysis in Organic Chemistry Teaching for Developing Organic Chemistry Thinking

DFT Study of Molecular and Electronic Structure of Y, La and Lu Complexes with Porphyrazine and Tetrakis(1,2,5-thiadiazole)porphyrazine.

Electronic and geometric structures of Y, La and Lu complexes with porphyrazine (Pz) and tetrakis(1,2,5-thiadiazole)porphyrazine (TTDPz) were investigated by density functional theory (DFT) calculations and compared. The nature of the bonds between metal atoms and nitrogen atoms has been described using the analysis of the electron density distribution in the frame of Bader’s quantum theory of atoms in molecule (QTAIM). Simulation and interpretation of electronic spectra were performed with use of time-dependent density functional theory (TDDFT) calculations. Description of calculated IR spectra was carried out based on the analysis of the distribution of the potential energy of normal vibrations by natural vibrational coordinates.Sample AvailabilityNot available.

Compound Heterozygous Frameshift Mutations in MESD Cause a Lethal Syndrome Suggestive of Osteogenesis Imperfecta Type XX.

Multiple genes are known to be associated with osteogenesis imperfecta (OI), a phenotypically and genetically heterogenous bone disorder, marked predominantly by low bone mineral density and increased risk of fractures. Recently, mutations affecting MESD, which encodes for a chaperone required for trafficking of the low-density lipoprotein receptors LRP5 and LRP6 in the endoplasmic reticulum, were described to cause autosomal-recessive OI XX in homozygous children. In the present study, whole-exome sequencing of three stillbirths in one family was performed to evaluate the presence of a hereditary disorder. To further characterize the skeletal phenotype, fetal autopsy, bone histology, and quantitative backscattered electron imaging (qBEI) were performed, and the results were compared with those from an age-matched control with regular skeletal phenotype. In each of the affected individuals, compound heterozygous mutations in MESD exon 2 and exon 3 were detected. Based on the skeletal phenotype, which was characterized by multiple intrauterine fractures and severe skeletal deformity, OI XX was diagnosed in these individuals. Histological evaluation of MESD specimens revealed an impaired osseous development with an altered osteocyte morphology and reduced canalicular connectivity. Moreover, analysis of bone mineral density distribution by qBEI indicated an impaired and more heterogeneous matrix mineralization in individuals with MESD mutations than in controls. In contrast to the previously reported phenotypes of individuals with OI XX, the more severe phenotype in the present study is likely explained by a mutation in exon 2, located within the chaperone domain of MESD, that leads to a complete loss of function, which indicates the relevance of MESD in early skeletal development. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR)..

Design and Performance of a Full Functional Electrochemical Cell for Lab Scale in-Situ GI-XRD Instruments

In-situ XRD may support electrochemical measurements by delivering analytical information about electrochemical processes. Since structural changes at the electrode/electrolyte interface are of specific interest, measurements are done usually in small angle reflection mode geometry. The surface sensitive grazing incidence – XRD (GI-XRD) in-situ technique allows the detection of short-lived electrode reaction products or products sensitive to ambient atmosphere exposure. This method finds applications for quite a number of investigations of electrochemical processes including corrosion, film growth and deposition, reconstruction of superficial regions, ion insertion battery materials, etc. The common cell designs for lab scale XRD equipment use thin electrolyte layers to avoid unacceptable beam intensity loss through water. The use of synchrotron radiation would reduce this shortcoming to some extent but is much less accessible.In 1986, Fleischmann et al. presented an in-situ XRD thin layer cell in reflection as well as in transmission mode, where a X-ray transparent Mylar foil was used as window material [1]. However, this geometry restricts the positioning of counter and reference electrodes and therefore has unfavorable current density distribution, has very small electrolyte volume, is vulnerable to side reactions with gas evolution and does not allow high flow rates for the solution. Thus, the general applicability is limited.In our proposed in-situ cell design for GI-XRD, the electrochemical cell is fully functional, avoiding all of the above mentioned drawbacks [2]. The solution of this issue is the "backside-illumination" (or "inverse" illumination) of a thin film working electrode applied on a thin polymer foil as a support by the X-ray beam at a small incident angle. On the opposite side a conventional electrochemical cell with reference electrode and counter electrode and sufficient solution volume can be used. The big advantage of this design is that the X-ray only has to penetrate the foil and the thin layer of electrode material resulting in high signals from the region of interest. It is used with a conventional laboratory X-ray source and does not need high intensity synchrotron radiation. With this cell design, problems with bulk solution resistance, inhomogeneous current-density distribution, insufficient bath agitation or gas evolution as side reaction are eliminated.In this contribution, details of the cell design, analysis of current density distribution within the thin current collector and the electrochemical cell, results of calibration measurements and measurements on copper as an example for a galvanic deposition/dissolution process are presented.[1] M. Fleischmann, A. Oliver, and J. Robinson, ‘In Situ X-ray diffraction studies of electrode solution interfaces’, Electrochimica Acta, vol. 31, no. 8, pp. 899–906, (1986)[2] S. Reither, W. Artner, A. Eder, S. Larisegger, M. Nelhiebel, C. Eisenmenger-Sittner, G. Fafilek, ‘On the In-Situ Grazing Incidence X-Ray Diffraction of Electrochemically Formed Thin Films’, ECS Transactions, 80 (10) 1231-1238, (2017) 10.1149/08010.1231ecst Figure 1