Investigation Of Structure Research Articles

DNP-assisted solid-state NMR enables detection of proteins at nanomolar concentrations in fully protonated cellular milieu.

With the sensitivity enhancements conferred by dynamic nuclear polarization (DNP), magic angle spinning (MAS) solid state NMR spectroscopy experiments can attain the necessary sensitivity to detect very low concentrations of proteins. This potentially enables structural investigations of proteins at their endogenous levels in their biological contexts where their native stoichiometries with potential interactors is maintained. Yet, even with DNP, experiments are still sensitivity limited. Moreover, when an isotopically-enriched target protein is present at physiological levels, which typically range from low micromolar to nanomolar concentrations, the isotope content from the natural abundance isotopes in the cellular milieu can outnumber the isotope content of the target protein. Using isotopically enriched yeast prion protein, Sup35NM, diluted into natural abundance yeast lysates, we optimized sample composition. We found that modest cryoprotectant concentrations and fully protonated environments support efficient DNP. We experimentally validated theoretical calculations of the limit of specificity for an isotopically enriched protein in natural abundance cellular milieu. We establish that, using pulse sequences that are selective for adjacent NMR-active nuclei, proteins can be specifically detected in cellular milieu at concentrations in the hundreds of nanomolar. Finally, we find that maintaining native stoichiometries of the protein of interest to the components of the cellular environment may be important for proteins that make specific interactions with cellular constituents.

Abstract 4485: Identification of novel lead compounds and repurposing FDA approved drugs as telomerase inhibitors using structure-based drug designing approach and their evaluation using in-vitro and ex-vivo assays

Abstract Introduction: Upregulated telomerase activity is an established hallmark in about 85-90% of cancer malignancies making it an attractive therapeutic target. However, the development of approved small-molecule telomerase inhibitors has been impeded by a lack of structural ambiguity for decades. In our study, we have employed a molecular dynamics approach to validate the binding site of BIBR1532, an approved telomerase inhibitor in the hTERT thumb domain followed by a structure-based drug designing approach to repurpose FDA-approved drugs and identify novel lead compounds targeting the enzyme. Material and Methods: Due to the unavailability of a co-crystalized structure of BIBR1532 with the catalytic hTERT thumb domain, we employed a Molecular dynamics-based method to identify and validate the exact binding site of the inhibitor. Two pharmacophore models were generated for the putative and newly identified binding pockets which were screened virtually through an anti-cancer library and Drug Bank database. The models were validated on the basis of the fit value of the BIBR1532 and selectivity value indicating the favorable feature set required. The top hits obtained were filtered using drug-likeliness parameters like Lipinski, ADME, and TOPKAT followed by redocking into their binding site. Finally, lead molecules that were able to dock in the new pocket were validated using Molecular Dynamics (MD)simulation studies and their binding free energy was calculated using MM-PBSA calculations followed by their evaluation using in-vitro TRAP assay. Results: Structural investigation, molecular docking studies, and confirmatory molecular dynamics revealed that the exact binding site of BIBR1532 is 8.4 Å away from the reported FVYL pocket strikingly with clinically relevant and characteristic interactions conserved. We have identified five lead compounds and four lead compounds from DrugBank and the anti-cancer library respectively, that were stable in the new binding pocket based on their MD trajectory analysis, and parameters like RMSD, RMSF, H-bonds and Radius of Gyration as well as their MM-PBSA scores. The lead compounds are being evaluated in vitro using TRAP assay and ex-vivo assays. Conclusion: The study identified five existing FDA-approved drugs in the market for other diseases as potential telomerase inhibitors alongside four novel compounds that can be used for the treatment of cancer in the future after further validation studies. Citation Format: Divpreet Kaur, Madhu Chopra, Daman Saluja. Identification of novel lead compounds and repurposing FDA approved drugs as telomerase inhibitors using structure-based drug designing approach and their evaluation using in-vitro and ex-vivo assays [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4485.

First-Principles Investigations of the Electronic Structure and Mechanical Characteristics of Nd3+-Doped YAlO3 Crystals

Near-infrared laser radiation based on Nd3+-doped yttrium ortho-aluminate (Nd:YAlO3, Nd:YAP) has garnered significant interest regarding solid-state lasers. Nevertheless, the crystal microstructures and electronic characteristics of Nd:YAP are still unclear, and the unique physical properties underlying its enormous applications require clarification. In this study, we conducted first-principles calculations at the atomic level to explore the electronic properties and mechanical characteristics of both pure YAP and Nd3+-doped YAP. The results suggest that the substitution of the Y3+ ion site with the Nd3+ impurity ion induces slight structural distortion in the YAP crystal lattice. An impurity band emerges between the original conduction band and the valence band, attributed to the 4f orbital of the Nd3+ ion, exerting a substantial influence on the narrowing of the band gap. Through an analysis of the mechanical characteristics of both pure YAP and Nd:YAP, we conclude that the incorporation of Nd3+ atoms leads to a reduction in the mechanical properties of YAP to a certain extent. Our study can serve as a foundational data source for investigations into material performance, especially for the application of Nd:YAP in solid-state laser systems.

A Comprehensive Study of Structural, Thermal, and Dielectric Properties of Melt-Processed Polypropylene/Ni0.9Zn0.1Fe2O4 Nanocomposites

This article explores the processing of structural, thermal, and dielectric properties of polypropylene (PP) polymer nanocomposites modified with Ni0.9Zn0.1Fe2O4. The PP/Ni0.9Zn0.1Fe2O4 nanocomposites are manufactured by the melt-processing method using a Brabender Polyspeed B. The XRD and FTIR structural investigations assure good incorporation of Ni0.9Zn0.1Fe2O4 into the PP matrix. It should be noted that adding Ni0.9Zn0.1Fe2O4 NPs to the PP polymer matrix enhances the polymer’s thermal stability. Utilizing the Coats–Redfern model, kinetic thermodynamic parameters such as activation energy (Ea), enthalpy (ΔH), entropy (ΔS), and Gibbs free energy (ΔG*) are deduced from TGA data. The dielectric results showed an increase in ε′ with the introduction of nanoparticles into the PP matrix. As the content of Ni0.9Zn0.1Fe2O4 NPs in these nanocomposite films increases, the loss tangent values decrease at higher frequencies while increasing at lower frequencies. The estimated εs and ε∞ of PP nanocomposites using Cole–Cole plots reveal an improvement when NPs are added to PP. We believe that the proposed work suggests a relevant step towards the practical application of PP/Ni0.9Zn0.1Fe2O4 nanocomposites.

Molecular Insights into the Variability in Infection and Immune Evasion Capabilities of SARS-CoV-2 Variants: A Sequence and Structural Investigation of the RBD Domain.

As severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants continuously emerge, an increasing number of mutations are accumulating in the Spike protein receptor-binding domain (RBD) region. Through sequence analysis of various Variants of Concern (VOC), we identified that they predominantly fall within the ο lineage although recent variants introduce any novel mutations in the RBD. Molecular dynamics simulations were employed to compute the binding free energy of these variants with human Angiotensin-converting enzyme 2 (ACE2). Structurally, the binding interface of the ο RBD displays a strong positive charge, complementing the negatively charged binding interface of ACE2, resulting in a significant enhancement in the electrostatic potential energy for the ο variants. Although the increased potential energy is partially offset by the rise in polar solvation free energy, enhanced electrostatic potential contributes to the long-range recognition between the ο variant's RBD and ACE2. We also conducted simulations of glycosylated ACE2-RBD proteins. The newly emerged ο (JN.1) variant has added a glycosylation site at N-354@RBD, which significantly weakened its binding affinity with ACE2. Further, our interaction studies with three monoclonal antibodies across multiple SARS-CoV-2 strains revealed a diminished neutralization efficacy against the ο variants, primarily attributed to the electrostatic repulsion between the antibodies and RBD interface. Considering the characteristics of the ο variant and the trajectory of emerging strains, we propose that newly developed antibodies against SARS-CoV-2 RBD should have surfaces rich in negative potential and, postbinding, exhibit strong van der Waals interactions. These findings provide invaluable guidance for the formulation of future therapeutic strategies.

One-pot synthesis, structural investigation, antitumor activity and molecular docking approach of two decavanadate compounds

Two bases-decavanadates coordination compounds [(C6H13N4)2][Mg(H2O)6]2[O28V10].6H2O (1) and [(C7H11N2)4][Mg(H2O)6][O28V10].4H2O (2) have been synthesized and well characterized using vibrational spectroscopy (infrared), UV–Visible analysis and single crystal X-ray diffraction technique. The formula unit, for both compounds, is composed by the decavanadate [V10O28]6−, hydrated magnesium ion, a counter anion and free water molecules. The transition metal adopts octahedral geometries in both compound (1) and (2). The existence of a multitude of hydrogen bonding interactions for both compounds provides a stable three-dimensional supramolecular structure. Optical absorption reveals a band gap energy indicating the semi-conductive nature of the compound. In this study, the cytotoxic and the anti-proliferative activities of compounds (1) and (2) on human cancer cells (U87 and MDA-MB-231) were investigated. Both compounds demonstrated dose-dependent anti-proliferative activity on U87 and MDA-MB-231 with respective IC50 values of 0.82 and 0.31 μM and 1.4 and 1.75 μM. These data provide evidence on the potential anticancer activity of [(C6H13N4)2][Mg(H2O)6]2[O28V10].6H2O and [(C7H11N2)4][Mg(H2O)2][O28V10].4H2O. Molecular docking of the compounds was also examined. Molecular docking studies were performed for both compounds against four target receptors and revealed better binding affinity with these targets in comparison to Cisplatin. Moreover, molecular docking investigations suggest that these compounds may function as potential inhibitors of proteins in brain and breast cells, exhibiting greater efficiency compared to Cisplatin.

Comparison of Optogalvanic and Laser-Induced Fluorescence Spectroscopy

When investigating complex atomic spectra, it may happen accidentally that two or even several transitions between different pairs of combining energy levels have nearly the same wavenumber, and the observed spectral lines are overlapping (blend situations). In such cases, investigations of hyperfine structures can be very helpful in the identification of the involved transitions. In this paper, two complicated blend situations within the spectra of lanthanide atoms (Praseodymium and Lanthanum) are discussed as examples. The experimental methods applied are optogalvanic and laser-induced fluorescence spectroscopy, combined with emission spectra gained via Fourier transform spectroscopy. It is shown that, in such cases, a combination of optogalvanic and laser-induced fluorescence detection is necessary to find all transitions contributing to the observed spectral signatures.

Optical properties of two-dimensional tin nanosheets epitaxially grown on graphene

Heterostacks formed by combining two-dimensional materials show novel properties which are of great interest for new applications in electronics, photonics and even twistronics, the new emerging field born after the outstanding discoveries on twisted graphene. Here, we report the direct growth of tin nanosheets at the two-dimensional limit via molecular beam epitaxy on chemical vapor deposited graphene on Al2O3(0001). The mutual interaction between the tin nanosheets and graphene is evidenced by structural and chemical investigations. On the one hand, Raman spectroscopy indicates that graphene undergoes compressive strain after the tin growth, while no charge transfer is observed. On the other hand, chemical analysis shows that tin nanosheets interaction with sapphire is mediated by graphene avoiding the tin oxidation occurring in the direct growth on this substrate. Remarkably, optical measurements show that the absorption of tin nanosheets exhibits a graphene-like behavior with a strong absorption in the ultraviolet photon energy range, therein resulting in a different optical response compared to tin nanosheets on bare sapphire. The optical properties of ultra-thin tin films therefore represent an open and flexible playground for the absorption of light in a broad range of the electromagnetic spectrum and technologically relevant applications for photon harvesting and sensors.

Hardness and fracture toughness enhancement in transition metal diboride multilayer films with structural variations

The simultaneous enhancement of hardness (H) and fracture toughness (KIC) through the formation of superlattice structures challenges the conventional belief that these quantities are mutually exclusive. Here, this approach has been applied to the transition metal diborides, whose inherent brittleness severely restricts their application potential. The mechanical properties of TiB2/TaB2 systems as a function of bi-layer period Λ are investigated, combining theoretical and experimental approaches. Density Functional Theory is used to investigate the structural stability and mechanical properties of stoichiometric hexagonal TiB2/TaB2 superlattices for Λ = 3.9 – 11.9 nm. The calculations predict the highest H = 38 GPa and KIC (100) of 3.3 MPa.m1/2 at the value of Λ = 5.2 nm. Motivated by the theoretical results, multilayer films with Λ = 4–40 nm were prepared by direct current magnetron sputtering. Due to the sputtering effects, the deposited diboride films differ significantly from the view of stoichiometry and structure. A detailed structure investigation reveals TiB2/TaB2 in form of superlattices exhibiting coherent interfaces for Λ = 4 nm. For higher Λ, parts of TaB2 layers transform from the crystalline to the disordered phase. These transformations are reflected in the mechanical properties as measured by nanoindentation and micromechanical bending tests. The evolution of hardness follows Hall-Petch behavior, reaching a maximum of 42 GPa at Λ = 6 nm. Enhancing fracture toughness involves more complex mechanisms resulting in two KIC maxima: 3.8 MPa.m1/2 at Λ = 6 nm and 3.7 MPa.m1/2 at Λ = 40 nm.

Design, Synthesis, Structural Investigation and Photo Induced Biological Investigations of Co(II), Ni(II) and Cu(II) Complexes Derived from N,O Donor Schiff Bases.

A series of chelated metal complexes, [Co(LI)2] (1), [Ni(LI)2] (2), [Cu(LI)2] (3) [Co(LII)2] (4), [Ni(LII)2] (5) and [Cu(LII)2] (6) were designed and synthesized from newly synthesized Schiff bases, LI = 2-((E)-(5-(4-fluorophenyl)isoxazol-3-ylimino)methyl)-5-methylphenol and LII = 2-((E)-(5-(4-fluorophenyl)isoxazol-3-ylimino)methyl)-4-chlorophenol. The synthesized compounds were characterized by elemental analysis, nuclear magnetic resonance spectroscopy (NMR), electronic spectroscopy (UV-Vis), infrared spectroscopy (FT-IR), magnetic susceptibility (µeff), electron spin resonance spectroscopy (ESR), Thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and powder X-ray diffraction analysis (P-XRD). The spectral investigations have been clearly suggested 1:2 (metal: ligand) stoichiometric complexes with square planar geometrical arrangement around the metal ion. The thermal gravimmetric analysis (TGA) of these complexes indicates greater thermal stability and various steps involved in thermal decomposition of metal complexes. The binding ability between these metal complexes and calf thymus DNA (CT-DNA) was investigated by UV-Vis, fluorescence spectroscopy and viscometric experiments, which disclosed that, the complexes interacted to CT-DNA via an intercalation binding mode. The cleavage property of metal complexes against pBR322 DNA has been explored by gel electrophoresis technique mediated by UV-illumination and H2O2, showed momentous cleavage activity. Antioxidant activity of all complexes was determined by DPPH free radical scavenging experiment and showed prominent antioxidant activity. Further, the antibacterial and antifungal activities of all compounds were screened against bacterial and fungal strains via in-vitro disc diffusion method. These studies revealed that the complexes showed comparatively more antimicrobial activity than free ligands against tested microbial strains.

In Silico Investigation of Parkin-Activating Mutations Using Simulations and Network Modeling.

Complete loss-of-function mutations in the PRKN gene are a major cause of early-onset Parkinson's disease (PD). PRKN encodes the Parkin protein, an E3 ubiquitin ligase that works in conjunction with the ubiquitin kinase PINK1 in a distinct quality control pathway to tag damaged mitochondria for autophagic clearance, i.e., mitophagy. According to previous structural investigations, Parkin protein is typically kept in an inactive conformation via several intramolecular, auto-inhibitory interactions. Here, we performed molecular dynamics simulations (MDS) to provide insights into conformational changes occurring during the de-repression of Parkin and the gain of catalytic activity. We analyzed four different Parkin-activating mutations that are predicted to disrupt certain aspects of its auto-inhibition. All four variants showed greater conformational motions compared to wild-type protein, as well as differences in distances between domain interfaces and solvent-accessible surface area, which are thought to play critical roles as Parkin gains catalytic activity. Our findings reveal that the studied variants exert a notable influence on Parkin activation as they alter the opening of its closed inactive structure, a finding that is supported by recent structure- and cell-based studies. These findings not only helped further characterize the hyperactive variants but overall improved our understanding of Parkin's catalytic activity and nominated targets within Parkin's structure for potential therapeutic designs.

Reconstructing the Holocene Development of Lake Chaika as an Example of Wetland Formation within the Sand Spit Environment Dynamics: A Case Study from the Curonian Spit, Southeastern Baltic, Russia

The paper provides original data that shed light on the formation dynamics of Lake Chaika, which is situated in the central part of the Curonian Spit and is the only large water body in the sand spits of the southeastern Baltic. Based on the multi-proxy approach, incl. investigation of the lithological structure of the bottom sediment cores, loss-on-ignition analysis, diatom analysis, study of macrofossil remains, and radiocarbon dating, we revealed that Lake Chaika was formed already in historical time, around 200 years ago. Before this period, the lake kettle, presumably, has not submerged during the Littorina transgressions, enabling the terrestrial development of the ecosystems on the moraine protrusion. During the mid-late Holocene (6700–150 cal BP), this depression was occupied by the peat-forming fen and alder carr communities. The peat deposits are separated from the overlying layers of gyttja by the thin sand horizon. We consider it a time marker for the so-called “sand disaster”, which occurred on the territory of the Curonian Spit in the 18th century (≈1700–1800). The change in the hydrological regime of the lake launched the ecosystem shifts during the last two centuries: from the water body to a wetland and vice versa. It is stated eight formation phases of the lake’s ecosystem: the terrestrial development without wet habitats (8900–6700 cal BP), the period of alder carrs (6700–3400 calBP), the sedge fen period (3400–450 cal BP), the period of inundated forest (1500–1700 AD), the “sand disaster” period (1700–1800 AD), the period of eutrophic water body (1800–1900 AD), the period of terrestrialised wetland (1900–1950 AD), and the period of secondary development of eutrophic water body (after 1950 AD).

Investigation of the dynamical structures of double-chain deoxyribonucleic acid model in biological sciences

The present research investigates the double-chain deoxyribonucleic acid model, which is important for the transfer and retention of genetic material in biological domains. This model is composed of two lengthy uniformly elastic filaments, that stand in for a pair of polynucleotide chains of the deoxyribonucleic acid molecule joined by hydrogen bonds among the bottom combination, demonstrating the hydrogen bonds formed within the chain’s base pairs. The modified extended Fan sub equation method effectively used to explain the exact travelling wave solutions for the double-chain deoxyribonucleic acid model. Compared to the earlier, now in use methods, the previously described modified extended Fan sub equation method provide more innovative, comprehensive solutions and are relatively straightforward to implement. This method transforms a non-linear partial differential equation into an ODE by using a travelling wave transformation. Additionally, the study yields both single and mixed non-degenerate Jacobi elliptic function type solutions. The complexiton, kink wave, dark or anti-bell, V, anti-Z and singular wave shapes soliton solutions are a few of the creative solutions that have been constructed utilizing modified extended Fan sub equation method that can offer details on the transversal and longitudinal moves inside the DNA helix by freely chosen parameters. Solitons propagate at a consistent rate and retain their original shape. They are widely used in nonlinear models and can be found everywhere in nature. To help in understanding the physical significance of the double-chain deoxyribonucleic acid model, several solutions are shown with graphics in the form of contour, 2D and 3D graphs using computer software Mathematica 13.2. All of the requisite constraint factors that are required for the completed solutions to exist appear to be met. Therefore, our method of strengthening symbolic computations offers a powerful and effective mathematical tool for resolving various moderate nonlinear wave problems. The findings demonstrate the system’s potentially very rich precise wave forms with biological significance. The fundamentals of double-chain deoxyribonucleic acid model diffusion and processing are demonstrated by this work, which marks a substantial development in our knowledge of double-chain deoxyribonucleic acid model movements.

Comprehensive phenotypic characterization of an allelic series of zebrafish models of NEB-related nemaline myopathy.

Nemaline myopathy (NM) is a rare congenital neuromuscular disorder characterized by muscle weakness and hypotonia, slow gross motor development, and decreased respiratory function. Mutations in at least twelve genes, all of each encode proteins that are either components of the muscle thin filament or regulate its length and stability, have been associated with NM. Mutations in Nebulin (NEB), a giant filamentous protein localized in the sarcomere, account for more than 50% of NM cases. At present, there remains a lack of understanding of whether NEB genotype influences nebulin function and NM-patient phenotypes. In addition, there is a lack of therapeutically tractable models that can enable drug discovery and address the current unmet treatment needs of patients. To begin to address these gaps, here we have characterized five new zebrafish models of NEB-related NM. These mutants recapitulate most aspects of NEB-based NM, showing drastically reduced survival, defective muscle structure, reduced contraction force, shorter thin filaments, presence of electron-dense structures in myofibers, and thickening of the Z-disks. This study represents the first extensive investigation of an allelic series of nebulin mutants, and thus provides an initial examination in pre-clinical models of potential genotype-phenotype correlations in human NEB patients. It also represents the first utilization of a set of comprehensive outcome measures in zebrafish, including correlation between molecular analyses, structural and biophysical investigations, and phenotypic outcomes. Therefore, it provides a rich source of data for future studies exploring the NM pathomechanisms, and an ideal springboard for therapy identification and development for NEB-related NM.

Structural and electrical investigation of rare-earth doped lead-free SrBi4Ti4O15 ceramics

Structural and electrical investigation of rare-earth doped lead-free SrBi4Ti4O15 ceramics

Remarkable dye adsorption capabilities in CaO-Doped-Zirconia systems

The realm of dye adsorption involving zirconia systems remains an untapped frontier, awaiting the unveiling of its complete prowess. The present work investigates the adsorption potentials of CaO-doped ZrO2 nanoparticles with varying doping of CaO (0, 7, 10, and 16 mol.%). With the highest adsorption capacity (of 760 mg/g) reported ever for any zirconia system, the 16 mol.% CaO-doped ZrO2 (16CaSZ) ultrafine nanoparticles portrayed fastest kinetics of dye (Congo red) removal. Along with effect of different pHs (in the presence of different anions such as Cl-, NO3–, SO42- and the mixture of them), a simulated wastewater (comprising urea, different salts, dye, sand, grass, engine oil etc.) was made to examine the efficacy of our nano-adsorbent. The 16CaSZ nanoparticles depicted excellent adsorption (∼99 %) in simulated industrial effluent and duplicated the same performance for pHs ranging from 2 to 10. Multitude of factors (e.g., phase-pure cubicity, highest oxygen vacancy content, pronounced surface area etc.) were credited for this chemisorption-based (R-SO3- interactions, as revealed by the structural and spectroscopic investigations on the post-adsorption products) remarkable adsorption process.

Spectroscopic and computational study of Favipiravir-Adenine cocrystallization biomolecular complex

The research focuses on the structural investigation of biomolecules and biomolecular complexes using the DFT method, spectroscopic techniques, and determining cocrystal formation. The significant difficulties in making new drug products are low oral bioavailability and poor aqueous solubility. However, the co-crystallization of biomolecules can enhance their solubility without changing their pharmacological properties. The optimized structure of the molecules is obtained using the B3LYP/6–311++G(d,p) basis set within the framework of Density Functional Theory (DFT). Various vibrational techniques such as Fourier Transform Infrared (FTIR), Raman, and Surface-Enhanced Raman Spectroscopy (SERS) are employed to characterize the monomers and their interacting system. Possible vibrational assignments along with Potential energy distribution (PED) analysis are carried out using Vibrational Energy Distribution Analysis (VEDA). Natural Bond Orbital (NBO), Non-Linear Optical (NLO), Non-Covalent Interaction (NCI), and Atoms in Molecule (AIM) study are carried out to understand the interacting mechanism in the Favipiravir-Adenine biomolecular complex. The study shows that there is charge transfer through inter and intramolecular interaction in the complex. The binding energy of protein and Ligand is investigated using the Autodock tool for the molecular docking method and the negative value of binding energy – 4.36 kcal/mol of Favipiravir-Adenine biomolecular complex exclaims good binding affinity with the chosen protein 6LU7. Lipinski's criteria for druglikeness also claim that monomers and synthesized biomolecular complexes have the potential to influence drugs with good oral bioavailability. Cocrystal formation is confirmed by the X-ray diffraction pattern. The Protox II software claims that the toxicity of the drug and synthesized biomolecular complex is class IV.

Investigation of the subsurface structure at the target site in Kumamoto, Japan, and the distributed data of the blind prediction exercise: report for the experiments for the 6th international symposium on effects of surface geology on seismic motion

This technical report explains details on the results of the investigation to build a subsurface structural model and a selection of earthquake data at the target site of the blind prediction exercise for “The 6th International Association of Seismology and Physics of the Earth’s Interior/International Association of Earthquake Engineering International Symposium on the Effect of Surface Geology on Seismic Motion (ESG6).” The selection process of the target site in the Kumamoto Plain, Japan, in ESG6 was explained with a historical review of the blind prediction tests in the previous ESG conferences. We have collected existing subsurface structural and earthquake data and conducted geophysical and geotechnical surveys in and around the target site to generate important velocity structure and the earthquake data used in the blind test. Microtremor data were obtained in triangular arrays ranging in side lengths from 1 to 962 m, and active surface wave data were derived along a 36-m line at the site. These data were provided for the prediction of a subsurface structural model in the first step of the blind prediction exercise. We also conducted a velocity logging in a borehole to a bottom depth of 39 m at the site and laboratory tests of soil samples from the borehole. We constructed a velocity profile of the shallow and deep sedimentary layers from a combination of the geophysical and geotechnical data at the site, and validated it by comparing the characteristics of the ground motion data from the moderate event. This “preferred velocity model” was provided as a standard model to the participants in the second and third steps of the blind prediction test to predict the earthquake ground motions of a moderate event and the mainshock of the 2016 Kumamoto earthquake.Graphical

Design, control, aerodynamic performances, and structural integrity investigations of compact ducted drone with co-axial propeller for high altitude surveillance

Compact multi-rotor unmanned aerial vehicles (UAVs) can be operated in many challenging environmental conditions. In case the UAV requires certain considerations in designing like lightweight, efficient propulsion system and others depending upon the application, the hybrid UAV comes into play when the usual UAV types cannot be sufficient to meet the requirements. The propulsion system for the UAV was selected to be coaxial rotors because it has a high thrust-to-weight ratio and to increase the efficiency of the propulsion system, a unique propeller was proposed to achieve higher thrust. The proposed propeller was uniquely designed by analyzing various airfoil sections under different Reynolds’s number using X-Foil tool to obtain the optimum airfoil section for the propellers. Since the design with duct increases efficiency, the Hybrid UAV presented in this paper has the modified novel convergent–divergent (C–D)-based duct which is a simplified model of a conventional C–D duct. The yawing and rolling maneuverings of the UAV could be achieved by the thrust vectoring method so that the design is simpler from a structural and mechanical perspective. The use of UAVs has risen in recent years, especially compact UAVs, which can be applied for applications like surveillance, detection and inspection, and monitoring in a narrow region of space. The design of the UAV is modeled in CATIA, and its further performance enactment factors are picked from advanced computational simulations relayed bottom-up approach. The predominant computational fluid dynamics (CFD) and fluid structure interaction (FSI) investigations are imposed and optimized through Computational Analyses using Ansys Workbench 17.2, which includes analysis of structural behaviour of various alloys, CFRP and GFRP based composite materials. From the structural analysis Titanium alloy came out to be the best performing materials among the others by having lower total deformation and other parameters such as normal and equivalent stress. The dynamics control response is obtained using MATLAB Simulink. The validations are carried out on the propeller using a thrust stand for CFD and on the duct through a high-jet facility for structural outcomes to meet the expected outcome.

Structural modeling and investigation of cantilever load-bearing mechanism in telescopic wing

Telescopic wing requires changing the wingspan under aerodynamic load. Structural deformation caused by forces and moments will result in increased driving forces or even stagnation. Deformation and distributed contact force of linear motion pair of the load-bearing mechanism which considers the geometric nonlinearity of guide rail is necessary to predict the driving force, the mechanical efficiency, or the stiffness matching in the optimal design process. Aiming at the cantilever load-bearing mechanism, the structural model was established in terms of the flexibility of the components, contact stiffness and other parameters on the friction of moving pairs are studied based on the modified chained-beam constraint model (CBCM). The model prediction accuracy is verified through simulation and experiment. The result shows that the friction force is related to the stiffness of guide rail, slider connector, ball bearing contact as well as the geometric parameters. Improper parameter selection will increase the friction force to more than twice the optimal solution.