Vibrational Study Research Articles

Elemental concentration in renal stones by wavelength dispersive X‐ray fluorescence spectrometry

AbstractRenal stone formation inside the kidney is one of the major causes of renal failure all over the world. To create preventative measures, it is crucial to examine renal stone's composition and identify the minerals that are responsible for their pathogenesis. Various concerns regarding the pathophysiology of renal stones remain unresolved and have been put forward. However, till date, the complete information is still unclear. In recent years, spectroscopic studies have gained much attention in identifying the chemical compositions that lead to the formation and growth of renal stones. This work employed wavelength‐dispersive X‐ray fluorescence (WDXRF) and Fourier transform infrared (FTIR) spectroscopy to study renal stones. WDXRF results of renal stone samples give the presence of numerous heavy and trace elements. Different elemental constituents like zinc (Zn), copper (Cu), iron (Fe), molybdenum (Mo), nickel (Ni), strontium (Sr), chromium (Cr), zirconium (Zr), palladium (Pd), bromine (Br), ruthenium (Ru), lead (Pb), and arsenic (As) were detected and quantified in the renal stones. Vibrational spectroscopic studies were carried out to know the chemical compositions of renal stones such as calcium oxalate monohydrate (COM), uric acid (UA), and carbonate apatite (CA). Quantitative results of WDXRF have been compared with the results from atomic absorption spectroscopy (AAS) of these stone samples. The available clinical details of the patients were correlated with the spectroscopic results obtained using WDXRF and FTIR spectroscopy.

Synthesis and experimental investigations of organic perovskite solar cell material; 2,5-bis(5-aminofuran-2-yl) thiophene 1,1-dioxide; photo-voltaic data validation using computational model and spectroscopic tools

The Doped crystal architectures based on the Perovskite structure are most promising for creating photovoltaic solar cells. In recent years, much research effort has been directed towards increasing the solar power conversion efficiency of organic crystal materials. The ultimate challenge is to improve the light-harvesting power gain in organic synthetic materials and it was proved from the attainment of the Birefringence (Δn) Kλ/t −1.98. In this context, we report herein fabrication of organic 2,5-bis(5-aminofuran-2-yl) thiophene 1,1-dioxide as a perovskite-like lattice in the form of molecular clusters. Its photo-conversion efficiency was calculated as 18%. Its short-circuit current density was determined as JSC = 0.91 mA/cm2, with open-circuit voltage VOC of 1.05 V. The charge transfer (CT) exciton binding energy variation of dielectric constant of the material medium has been calculated. The diffusion path length was defined as <10 Å and the direct band gap was measured as 2.15 eV. The Urbach energy of the prepared sample was estimated as 110–220 meV. The molecular mechanism of exciton productions in the photo-voltaic process has been probed through the use of computational software and experimental tools. The light harvesting ability has been assessed in terms of morphological, optical and electro-optical properties. To characterize weak interactions between the organic molecular sites, vibrational studies have been carried out on polar and nonpolar bonds. The production of Frenkel excitons at the HOMO-LUMO interface and the binding energy variation for electron-hole dissociation has been estimated from the Coulomb capture radius. The photo-energy conversion efficiency and fill factor (FF = 0.511) have been estimated to prove the efficiency of the cell.

Flammability and vibrational study of graphene incorporated epoxy/ramie/glass hybrid nanocomposite

AbstractHybrid polymer composites are vastly used in aerospace, construction, and automotive fields. This study aims to analyze the flammability and vibrational behavior of graphene incorporated epoxy/ramie/glass (ERG) hybrid nanocomposite. The samples were prepared with different weight percentage of graphene (GR) through hand layup method, followed by vacuum bag technique. The samples were analyzed for water intake, porosity, mechanical strength, fractography, vibrational property together with flammability of the material. GR addition depletes water intake and porosity by 11.5% to 5.3% and 6.2% to 2.2%, respectively. It increases hardness and flexural strength up to 25% and 41%, with a reduction in tensile property of the composites. Besides, GR nanocomposites show improved damping properties, owing to stick‐slip mechanism exhibited at epoxy and GR interface. Also, GR addition declines burning rate of ERG at high concentrations since it does not score any grade in flammability test. This work found that the incorporation of GR in ERG composite enhances mechanical properties and decreases water intake. A decrease in the burning rate of the ERG composite could be achieved by incorporating graphene particles, which could be used for structural applications (car door‐panels, ballistic, and aerospace) leading to delay in burning rate of the developed composites when exposed to fire during accidents.

Thermophysical and lattice vibrational study of thorium telluride (ThTe) by use of three-body force shell model

In this paper, a complete lattice study of thorium telluride (ThTe) in the effects of three-body interaction (TBI) in the framework of RIM and RSM models is reported. By use of the present model, I have theoretically reported elastic constants, pressure derivatives, dispersion relation curve, specific heat curve, combined density of states (CDS) and equation of state of the ThTe compound. The achieved results are good with experimentally reported results and have given very important information about this compound for further investigation.

Block Copolymer-Assisted Synthesis of Iron Oxide Nanoparticles for Effective Removal of Congo Red.

Iron oxide nanoparticles (IONPs) were synthesized via a block copolymer-assisted hydrothermal method and the phase purity and the crystal structure were investigated by X-ray diffraction. The Rietveld analysis of X-ray diffractometer spectra shows the hexagonal phase symmetry of α-Fe2O3. Further, the vibrational study suggests Raman active modes: 2A1g + 5Eg associated with α-Fe2O3, which corroborates the Rietveld analysis and orbital analysis of 2PFe. The superparamagnetic behavior is confirmed by magnetic measurements performed by the physical properties measurement system. The systematic study of the Congo red (CR) interaction with IONPs using a UV-visible spectrophotometer and a liquid chromatography-tandem mass spectrometry system equipped with a triple quadrupole mass analyzer and an electrospray ionization interface shows effective adsorption. In visible light, the Fe2O3 nanoparticles get easily excited and generate electrons and holes. The photogenerated electrons reduce the Fe3+ ions to Fe2+ ions. The Fe2+/H2O2 oxidizes CR by the Fenton mechanism. The strong adsorption ability of prepared nanoparticles towards dyes attributes the potential candidates for wastewater treatment and other catalytic applications.

An approach to modeling vibrations of systems composed of beams, rigid bodies, and point masses

An approach for vibration analysis of three-dimensional motion beam systems is formulated. The proposed method employs analytical solutions that are used to formulate a unified, three-dimensional dynamic representation the elements of beam systems, including beams, rigid bodies, and point masses. Interconnections between system’s components and their connections to the inertial frame are formulated as motion constraints. The interconnections can be rigid or flexible and can be located at arbitrary locations on the system components. The unified representations of different types of system elements and of different interconnection allows vibration analysis of complex beam systems. A procedure is developed for computation of natural frequencies and mode shapes by employing a sequence of orthogonal transformations. A three-dimensional structure that includes flexibly and rigidly connected beams and rigid bodies with different types of connections, is used to demonstrate the capabilities of the proposed method. The accuracy of the approach is verified by restricting the structure to planar motion with rigid connections and comparing the results to results of obtained in previous studies. The example structure is used to demonstrate the ability of the proposed approach to conduct vibrational analysis study of three-dimensional structures with different boundary conditions. Moreover, it also demonstrates suitability of the approach for studying sensitivity of vibrations characteristics, such as modal frequencies, with respect to system parameters, e.g. interconnections stiffness.

Skin surface lipids photo‐oxidation: A vibrational spectroscopy study

AbstractSkin surface lipid (SSL) film is a mixture of sebum and epidermal lipids protecting the skin from the effects of the environment such as solar radiation. SSLs are a suitable target and scavenger for all reactive oxygen species (ROS) generated in the skin. In the SSLs, vitamin E has been identified as one of the main antioxidants that can capture ROS. This paper is the third part of a global study that evaluates the effect of solar radiation on the lipid classes that constitute SSLs. In the first two parts, the effect of solar radiation on fatty acids and triglycerides was studied using vibrational spectroscopy. In this part, the effect on the other lipid classes such as squalene (SQ), cholesterol (Chol), and wax ester (WE) (Palmitoleyl Palmitate) was studied and then the behavior of vitamin E under solar radiation was monitored. Finally, SSLs were irradiated and analyzed using vibrational spectroscopy and HT‐GC/MS to respectively follow the oxidation process and to identify the first target of solar radiation in SSLs. When irradiated alone, SQ oxidation process was detectable only after 2430 J/cm2 dose. Similar observations were obtained for vitamin E (after 1620 J/cm2). No changes were observed on the cholesterol and on the wax ester (Palmitoleyl Palmitate). In contrast, when extracted human SSLs film was irradiated, the more marked modifications were observed on SQ. This confirmed the antioxidant role of SQ by scavenging free radicals generated from the oxidation of polyunsaturated fatty acids (PUFA).

Synthesis, single crystal X-ray analysis and vibrational spectral studies of 3,4-di(1H-indol-3-yl)-1H-pyrrole-2,5‑dione

Indole derivatives are a very important class of heterocyclic compounds that widely exist in natural products and biologically active molecules. In this paper, the title compound 3,4-di(1H-indol-3-yl)-1H-pyrrole-2,5‑dione was designed and synthesized by a three-step reaction of amidation, nucleophilic substitution and cyclization. The title compound was first characterized by four main spectra. Next, the single crystal structure of the title compound was confirmed by X-ray diffraction analysis, and the optimized crystal structure was determined by DFT calculation using the B3LYP/6–311+G(2d, p) basis set. The results show that the molecular structure after DFT optimization is consistent with the crystal structure determined by X-ray single crystal diffraction. In addition, the geometric parameters, MEP, FMO, Hirshfeld analysis, and infrared characteristic vibrational absorption bands of the title compound were also analyzed. Finally, this study also performed antitumor analysis of A549.

Selective Action of Antimalarial Hydroxychloroquine on the Packing of Phospholipids and Interfacial Water Associated with Lysosomal Model Membranes: A Vibrational Sum Frequency Generation Study.

Understanding the structural change of lysosomal membranes induced by hydroxychloroquine (HCQ) drug is essential as it has been considered as one of the probable mechanisms of its antimalarial action. In this context, vibrational sum frequency generation (VSFG) spectra of the O-H region of water and C-H of the hydrocarbon chain of negatively charged and zwitterionic phospholipids associated with the lysosomal membrane in the absence and presence of different concentrations of HCQ have been measured at the air/water interface. The interfacial water at the negatively charged and zwitterionic lipids gets restructured in the presence of HCQ; however, the mechanism of restructuring is different due to the charge of the head groups of lipids. Interestingly, the presence of HCQ leads to a disorder in the negatively charged lipids, irrespective of their chemical nature, mainly by creating the gauche defect in the hydrocarbon chain of the lipid. In contrast, the ordering of the zwitterionic lipid does not show any appreciable change with the addition of HCQ. The finding on the selectivity of HCQ in affecting the ordering of the lipid depending on its head group charge and restructuring of interfacial water may be useful in understanding the molecular level mechanism of the antimalarial action of HCQ.

Molecular dynamics study of collective water vibrations in a DNA hydration shell

The structure of DNA double helix is stabilized by water molecules and metal counterions that form the ion-hydration shell around the macromolecule. Understanding the role of the ion-hydration shell in the physical mechanisms of the biological functioning of DNA requires detailed studies of its structure and dynamics at the atomistic level. In the present work, the study of collective vibrations of water molecules around the DNA double helix was performed within the framework of classical all-atom molecular dynamics methods. Calculating the vibrational density of states, the vibrations of water molecules in the low-frequency spectra ranged from [Formula: see text]30 to [Formula: see text]300 [Formula: see text] were analyzed for the case of different regions of the DNA double helix (minor groove, major groove, and phosphate groups). The analysis revealed significant differences in the collective vibrations behavior of water molecules in the DNA hydration shell, compared to the vibrations of bulk water. All low-frequency modes of the DNA ion-hydration shell are shifted by about 15-20 [Formula: see text] towards higher frequencies, which is more significant for water molecules in the minor groove region of the double helix. The interactions of water molecules with the atoms of themacromolecule induce intensity decrease of the mode of hydrogen-bond symmetrical stretching near 150 [Formula: see text], leading to the disappearance of this mode in the DNA spectra. The obtained results can provide an interpretation of the experimental data for DNA low-frequency spectra and may be important for the understanding of the processes of indirect protein-nucleic recognition.

Vibrational study of the various forms of (solvated or unsolvated) mobile proton in materials for storage and production systems based on the hydrogen vector. Advantages, limitations and open questions

Vibrational study of the various forms of (solvated or unsolvated) mobile proton in materials for storage and production systems based on the hydrogen vector. Advantages, limitations and open questions

Synthesis, structural characterizations and vibrational spectroscopy studies of Ba2 −xPbxSr(PO4)2; (0 ≤ x ≤ 2)

Synthesis, structural characterizations and vibrational spectroscopy studies of Ba2 −xPbxSr(PO4)2; (0 ≤ x ≤ 2)

Buckling and free vibration analysis of bio-inspired laminated sandwich plates with helicoidal/Bouligand face sheets containing softcore

Helicoidal laminates inspired by mantis shrimp crustacean can sustain higher loads compared to conventional laminated structures. However, there is still a lack of bending studies on the plates inspired by these helicoidal structures. The buckling and free vibration studies have been undertaken in the present work on the laminated composite and sandwich plates inspired by the helicoidal structures of the biological characters. Investigations are carried out using higher-order zigzag theory. For sandwich plates, the top and bottom face sheets are assumed to be made up of helicoidal layup schemes. Different kinds of helicoidal schemes, namely, recursive, exponential, semicircular, Fibonacci, and linear helicoidal are considered during the analysis. The buckling and free vibration behavior of helicoidal-based laminated sandwich plates are compared with the conventional laminated sandwich plates such as uniform distribution and cross-ply configurations. The influence of the number of layers, helicoidal schemes, geometric properties, and end conditions on the buckling and free vibration analysis of bio-inspired helicoidal laminated composite and sandwich plates is carried out in detail.

Effect of methane supplementation on the performance, vibration and emissions characteristics of methane-diesel dual fuel engine

The increasing energy demands, especially in transportation sector, and the challenges of excess pollution and environmental degradation caused due to the conventional fuels, as well as their limited availability has highlighted the need to look for alternative fuels to sustain future needs. Methane is capable of catering to these demands due to its wide availability, both in renewable and non-renewable energy sources. The present work explores the effect of methane supplementation on the performance and emission characteristics as well as the vibrations in internal combustion engines. A four-stroke compression ignition engine is modified to run as a methane-diesel dual fuel engine where methane is inducted through intake manifold and diesel is directly injected into cylinder. Tests are performed by varying engine load and methane energy levels up to 75%. Our study shows that the participation of methane at lower load conditions is weak due to its higher auto ignition temperature and higher calorific value. The emissions, particularly CO and NO, are observably higher at 75% load conditions due to the efficient combustion and higher temperature at higher load conditions. The vibration studies on the dual fuel combustion indicates that the introduction of methane also suppresses the frequency spectrum of combustion noise and reduces the ringing intensity level of vibration for complete spectrum of engine loads, with the effect being prominent at higher loads. Overall, our results suggests that combustion of methane in dual fuel diesel engine shows distinct characteristics at contrasting load conditions.

Do we need to satisfy natural boundary conditions in energy approach to nonlinear vibrations of rectangular plates?

Despite a large literature, it seems still unclear if it is necessary to satisfy the natural boundary conditions in an energy approach to the study of nonlinear vibrations of rectangular plates. In the present study, which is based on Lagrange equations, the case of simply supported movable edges is considered. In the past, special nonlinear terms were added to the in-plane displacements to satisfy the natural boundary conditions. However, it was unclear if this was just helping the fast convergence of the series, reducing the number of degrees of freedom in the model, or it was actually necessary. In fact, it is well-known that for linear vibrations only geometric (essential) boundary conditions must be satisfied in variational energy approaches like the Rayleigh-Ritz method. Therefore, this doubt should be clarified. In the present study, accurate expansions of the plate displacements are introduced with additional in-plane trigonometric terms. They allow to satisfy the natural boundary conditions by energy minimization without the introduction of additional nonlinear terms. Nonlinear damping is also introduced in order to obtain results which agree with experiments.

Experimental investigation on the vortex-induced vibration of an arch steel bridge tower

This paper reports the wind tunnel study of the vortex-induced vibration (VIV) of a free-standing steel arch bridge tower with pentagon cross-section. The tests were carried out at different yaw angles β (0°–90°) of wind flow by employing a 1:50 scaled aeroelastic model. A series of aerodynamic measures were studied to mitigate the VIV of the tower at the most unfavorable yaw angle. Effects of turbulence intensity and structural damping on the VIV performance of the tower were evaluated. A sleeve-type eddy current damper (ECD) for increasing the structural damping of aeroelastic model was designed for reserved emergency measures. Experimental results indicate that the VIV occurs for a few yaw angles at wind velocity of 15–18 m/s and the maximum VIV amplitude happens for β = 35°. The aerodynamic measures are effective for some yaw angles but become invalid for other yaw angles. Compared to those in smooth flow, the VIV amplitude drops by 65% for a turbulence intensity of 8.5%. The VIV of the tower can be effectively suppressed by the eddy current damper which provides additional damping to the aeroelastic model. The sleeve-type eddy current damper is shown to be a convenient device to adjust the damping for aeroelastic models.

Synthesis and Characterization of a Bridging Cerium(IV) Nitride Complex.

Complexes featuring lanthanide-ligand multiple bonds are rare and highly reactive. They are important synthetic targets to understand 4f/5d-bonding in comparison to d-block and actinide congeners. Herein, the isolation and characterization of a bridging cerium(IV)-nitride complex: [(TriNOx)Ce(Li2μ-N)Ce(TriNOx)][BArF4] is reported, the first example of a molecular cerium-nitride. The compound was isolated by deprotonating a monometallic cerium(IV)-ammonia complex: [CeIV(NH3)(TriNOx)][BArF4]. The average Ce═N bond length of [(TriNOx)Ce(Li2μ-N)Ce(TriNOx)][BArF4] was 2.117(3) Å. Vibrational studies of the 15N-isotopomer exhibited a shift of the Ce═N═Ce asymmetric stretch from ν = 644 cm-1 to 640 cm-1, and X-ray spectroscopic studies confirm the +4 oxidation state of cerium. Computational analyses showed strong involvement of the cerium 4f shell in bonding with overall 16% and 11% cerium weight in the σ- and π-bonds of the Ce═N═Ce fragment, respectively.

SERS spectroscopy for the therapeutic N-butyl-2-isonicotinoylhydrazine-1-carboxamide in silver nanocolloids at different concentrations: Experimental and DFT investigations

SERS at different concentrations and vibrational spectroscopic studies of N-butyl-2-isonicotinoylhydrazine-1-carboxamide (INC) are reported. DFT calculations based on silver cluster model and TD-DFT calculations support experimental observations. Raman band enhancements that are only present in some of the SERS spectra further point to the contribution of charge transfer interactions to the overall enhancements INC's Raman modes. The presence of the inactive nR bands in the SERS spectrum is due to the presence of Ag and these show the chemisorption nature of INC with the silver surface in an inclined orientation according to selection rules. The method created in this study can accurately quantify INC and might be applied to medications with structural relevance.

Structural and Raman studies of MnO2 and Mn2O3 nano-particles

In this work MnO 2 with secondary phases Mn 2 O 3 nano-particles were synthesized by using sol- gel route method. This method was carried out under the thermal treatment at 500 °C for 2 h. Structural parameters were extracted by X-ray Diffractometer (XRD). The phase and crystallite size of MnO 2 and secondary phase Mn 2 O 3 were figured out by XRD. The peaks from XRD show different crystalline sizes are ∼59 nm, 51 nm, 53 nm, 63 nm, and 65 nm. The average crystallite size is 58 nm. The Raman studies of the sample were also carried out. The vibrational studies through Raman Spectroscopy technique gives peak at 509 cm −1 shows MnO 2 .

Design of Fiber Bragg Grating Sensor for Eccentricity Measurements in Ball Bearings

This study reports a novel, cost effective method to measure the eccentricity and vibration of a ball bearings by using fiber Bragg grating (FBG) sensors in electrical and mechanical motors. It will help to monitor the health condition of the motors. Bearings are playing a major role in industry, and it directly depends on smooth working of machine without any vibration and breakdown. Usually, health monitoring of rotating machines is done by sensing the vibration signals from the machine. This study provides an analysis of the bearing faults based on the sensor axial strain information obtained from the FBG sensors. Vibration study has been done for both healthy and defected bearings with designed 3-D printed sensor module. Different rpm tests are performed on the motor for vibrational analysis. Furthermore, hammering experiments are done on the sensor module to study resonant frequency characteristics of the sensor.