Plane Bending Vibration Research Articles

Characterization and luminescence properties of Eu3+ doped BaCO3 nanoparticles synthesized by autocombustion method

Nanostructured powders of undoped and europium (Eu3+) doped barium carbonate (BaCO3) were prepared by the autocombustion method. We investigated the influence of Eu3+ doping on the optical properties of barium carbonate. The samples nanostructures were characterized by X-ray powder diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential thermal analysis (DTA) and photoluminescence (PL). The results obtained by XRD revealed that the samples consist of the BaCO3 phase with orthorhombic structure having the space group Pmcn, retaining this crystalline phase after doping with Eu3+. These products were found for undoped and BaCO3: Eu3+ nanoparticles with 56–71 nm and 49–60 nm ranges, respectively. SEM reveals that the barium carbonate nanoparticles had a spherical morphology. Symmetric stretches, asymmetric stretches, and in plane bending vibrations, and out of plane of CO32− complexes have detected. The photoluminescence of the obtained BaCO3:Eu3+ were studied. The CIE co-ordinates for the Eu3+ doped BaCO3 were x = 0.580 and y = 0.330. From the CIE chromaticity diagram for the emissions of Eu3+ doped BaCO3. The material has such color purity and reaches 76%. Thus, having color tenability and has been considerate as a candidate of the laser emission.

Synthesis and Structural Characterization of Fly Ash Based Mineral Polymer Precursors

Preparation of mineral polymer materials with fly ash is one of the effective ways to realize the green and comprehensive utilization of fly ash. Using the sol-gel method mineral aggregate material precursor, swe tudied the different sources of silicon and aluminum, synthesis temperature, different Si/Al ratio, different dosages of ethanol, and other influence factors under the conditions of the synthesis, and the structure of the sample using the means of XRD, SEM, TG, IR on the synthesis of silica-alumina precursor sample performance and structure are analyzed. The results showed that the optimum preparation conditions were obtained when the Si/Al ratio was 10:1, the synthesis temperature was 70°C, and the sample was calcined at 850°C for 3 h with the highest synthesis rate of 81.33%. The Si-Al precursors prepared are amorphous—phase amorphous grid—space structures. The infrared analysis indicated that the synthesized sample had a Si-O-Si bond, but the absorption peak and characteristic peak were obviously different under the conditions of different synthesis temperatures, different Si/Al ratios, and different ethanol dosage. For example, at 806 cm−1 and 1,395 cm−1, they correspond to the absorption peak of Si-OH bending vibration and shear bending vibration and plane bending vibration of C-H without complete reaction respectively. SEM observation shows that the size of the synthesized Silicon aluminum precursors sample is small and the distribution is uniform. The in-depth study on the preparation process and reaction mechanism of mineral polymer precursorswill bring broad prospects for the application and development of mineral polymer precursors themselves.

Neutron-γ discrimination with organic scintillator crystal: 9-Phenylcarbazole (9-PCz) grown by Bridgman – Stockbarger method

Organic scintillator crystal 9-Phenylcarbazole (9-PCz) has been grown using Bridgman -Stockbarger technique. The crystal structure, lattice parameter and bond angle values are measured from single-crystal X-ray diffraction (SXRD) analysis. C–H inplane bending and out of plane bending and skeletal vibrations of 9-PCz molecule were identified from vibrational spectral analysis. UV–visible NIR spectral study shows that the crystal exhibits around 50% of transmittance in the infrared region and the direct optical bandgap energy is calculated to be 3.36 eV. Thermal properties of grown 9-PCz material were measured using thermogravimetric and differential thermal analyses (TG-DTA). The photoluminescence (PL) measurements show two emission bands with a maximum peak at 365 nm and a shoulder peak at 381 nm. X-ray induced luminescence spectrum of 9-PCz crystal exhibits a maximum emission peak at 381 nm. Scintillation decay time measurement shows the major component of 18 ns decay time. The pulse shape discrimination (PSD) capability of the grown crystal sample was studied for the signals induced by α-particles and γ-rays from 241Am and 137Cs sources, respectively. The figure of merit (FOM) is found to be 2.69. The preliminary results showed that the present studied organic crystal (9-PCz) scintillator can be considered in the field of fast neutron detection application.

INFRARED SPECTRA OF THE FREE BASE OF PHTHALOCYANINE AND ITS DEUTERATED DERIVATIVES AND THEIR INTERPRETATION

The IR spectra of the free base of phthalocyanine and three of its deuterium derivatives have been studied experimentally and theoretically. Calculations of normal vibrations by the density functional theory method made it possible to carry out a detailed interpretation of the spectra and their changes upon isotope
 substitution. Vibrations, frequencies of which are sensitive to the isotopic substitution of various positions of the molecule, have been established. A high delocalization of plane bending vibrations of NH bonds has been noted with the greatest change in vibration frequencies not exceeding 85 cm–1.

Electroconductive Polyaniline–Ag-ZnO Green Nanocomposite Material

Metal-conducting polyaniline (PANI)-based nanocomposite materials have attracted attention in various applications due to their synergism of electrical, mechanical, and optical properties of the initial components. Herein, metal-PANI nanocomposites, including silver nanoparticle-polyaniline (AgNP-PANI), zinc oxide nanoparticle-polyaniline (ZnONP-PANI), and silver-zinc oxide nanoparticle-polyaniline (Ag–ZnONP-PANI), were prepared using the two processes. Nanocomposite-based electrode platforms were prepared by depositing AgNPs, ZnONPs, or Ag–ZnONPs on a PANI modified glass carbon electrode (GCE) in the presence of 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide/N-Hydroxysuccinimide (EDC/NHS, 1:2) as coupling agents. The incorporation of AgNPs, ZnONPs, and Ag–ZnONPs onto PANI was confirmed by UV-Vis spectrophotometry, which showed five absorbance bands at 216 nm, 412 nm, 464 nm, 550 nm, and 831 nm (i.e., transition of π-π*, π-polaron band transition, polaron-π* electronic transition, and AgNPs). The FTIR characteristic signatures of the nanocomposite materials exhibited stretching arising from C–H aromatic, C–O, and C–N stretching mode for benzenoid rings, and =C–H plane bending vibration formed during protonation. The CV voltammograms of the nanocomposite materials showed a quasi-reversible behavior with increased redox current response. Notably, AgNP–PANI–GCE electrode showed the highest conductivity, which was attributed the high conductivity of silver. The increase in peak currents exhibited by the composites shows that AgNPs and ZnONPs improve the electrical properties of PANI, and they could be potential candidates for electrochemical applications.

Assessment of Physicochemical Properties and Mineral Compositions of Almond (Prunus amygdalus) Gum of Libyan Origin

Twenty-five authentic samples of Prunus amygdalus gum samples were collected from five different locations in northwest of Libya. Different physicochemical methods were used to characterize this type of gum samples. The mean values of the moisture ranged from 12.55 to 14.93%, ash mean values 4.03 to 4.62%, pH 3.89 to 4.40, W.H.C 52.85 to 60.0%, and O.H.C 136.2 to 156.3%. Solubility of Prunus amygdalus gum showed that it had low solubility in distilled water with the mean values ranged from 20.01 to 35.40%, but it dissolved perfectly in alkali media where solubility increased to 96.3% in 0.05 M Na2CO3. The study exhibited that the mean values of cationic concentration in %(w/w) such as calcium was ranged from 0.552 to 0.585, potassium 0.402 to 0.505, iron 0.0975 to 0.1125, and sodium 0.064 to 0.079, which indicates that Ca has the highest concentration of metallic ions present. Atomic absorption method indicate that all samples contain traces of elements, Li, Cr, Mn, Ni, Zn, Pb, Hg, and Cd. The main functional groups recorded from FTIR spectrum included bands at 3293 cm-1 (O-H in carboxylic group), 1601.77 cm-1 (C=O, amide N-H bend, and C=C), 1357.53 cm-1 (CH3-, and C-O-H in- plane bending vibration), and 1025.74 cm-1 (C-O stretching).

Theoretical investigation of the vibronic phosphorescence spectra and quantum yields for iridium(III) complexes with 2-(2,5,2',3',4',5',6'-heptafluoro-biphenyl-4-yl)-pyridine as the primary ligand.

Cyclometalated Ir(III) complexes are widely used as phosphorescent materials in organic light-emitting diodes. In this work, the vibrationally resolved phosphorescence spectra of an experimental reported and four novel designed Ir(III) complexes with 2-(2,5,2',3',4',5',6'-heptafluoro-biphenyl-4-yl)-pyridine (HFYP) as primary ligand are investigated by theoretical calculations. The ancillary ligands are 3-(pentafluorophenyl)-pyridin-2-yl-1,2,4-triazolate (exp3), 3-(trifluoromethyl)-pyridin-2-yl-1,2,4-triazolate (5), 5-methylsulfonyl-2-oxyphenyl-2-oxazole (6), 5-trifluoromethyl-2-oxyphenyl-2-oxazole (7), 2-(3-(trifluoromethyl)-1H-1,2-diazol-5-yl)pyridine (8), respectively. Phosphorescence spectra show that there are mainly two strong peaks, which can be ascribed as low-frequency vibrational modes such as the rotation of ligand plane, and benzene ring/pyridine ring in ligand HFYP1 skeleton vibration coupled with CH in pyridine ring in plane bending vibration. The phosphorescence quantum yields were quantitatively determined by evaluating radiative decay rate constant kr, intersystem crossing rate constatant kISC and temperature-dependent nonradiative decay rate constant knr(T). It shows that the quantum yields of compounds exp3, 5 and 8 are relative higher, while those of compounds 6 and 7 are much smaller. This is mainly caused by larger knr(T) of compounds 6 and 7. It is anticipated that in Ir(III) complex with HFYP primary ligand, pyridin-2-yl-1,2,4-triazolate, 1,2-diazol-5-yl-pyridine are good ancillary ligand, while 2'-oxyphenyl-2-oxazoline is not appropriate to be ancillary ligand.

Analysis of the Structures and Thermal Properties of Hexanediamine Adipate and Pentanediamine Adipate

Hexanediamine adipate, pentanediamine adipate and bio-based pentanediamine adipate were prepared by adipic acid reaction with 1,6-hexanediamine, 1,5-pentanediamine and bio-based 1,5-pentanediamine, respectively. Their structures and thermal properties have been analyzed by infrared spectra, SEM, DSC and TGA. Infrared spectra showed the main differences between 1,6-hexanediamine and 1,5-pentanediamine for the deformation vibration and out of plane bending vibration of N−H. Hexanediamine adipate and pentanediamine adipate had the difference at the asymmetric stretching vibration of −COO-−. The crystal morphologies of hexanediamine adipate and pentanediamine adipate showed dendritic and acicular, respectively. The melting point of pentanediamine adipate, pentanediamine adipate and bio-based pentanediamine adipate were 208.0 °C, 182.3 °C and 182.9 °C, respectively. The polymerization of hexanediamine adipate, pentanediamine adipate and bio-based pentanediamine adipate happened at 201.0, 190.2 and 194.9 °C, respectively. And the decomposition temperature of PA66, PA56 and bio-based PA56 were 401.8, 403.5 and 405.2 °C, respectively.

THE OSCILLATIONS OF ROD CONSTRUCTIONS WITH TAKING INTO ACCOUNT THE ENERGY DISSIPATION

The paper presents a solution of the problem of beam oscillation with the energy dissipation. In studying of the dissipation of the internal energy in the materials the one of the complicated problems is the problem when the material is acting by a variable load. If the frequency of the exciting loads has definite ratios with the eigenfrequency of oscillations, the level of dynamic loads is sharply increases. If the dependence of the logarithmic decrement of the amplitude at the free vibrations, it can be used to calculate the resonant vibrations. When we solving problems for rod constructions the greatest interest has the spectrum of the natural frequencies and corresponding mode shapes. It is proposed to use a two-node finite element in the case of plane bending vibrations of the rod. In this case, the nodal unknowns are deflections and turning angles the nodes. For the approximation of displacements we use a third-order polynomial. To find the spectrum eigenfrequencies and mode shapes is suggested to use a method of increasing stiffness, which is based on the minimization of functional of the Rayleigh type. The method coordinate wise descent is applied to solve the problem of minimizing the functional, which is one of the methods of nonlinear programming. We present numerical algorithm for solving the dynamics of rod structures.

Combining near and mid infrared spectroscopy for heavy oil characterisation

In this study, the potential of combining NIR and MIR spectral range for the determination of Saturate, Aromatic, Resin and Asphaltene (SARA) contents in heavy oils was evaluated. The work aimed at better understanding the contribution of each spectral range and, at highlighting complementary information for the description of SARA contents. A further objective was to observe if more accurate models could be obtained combining the two spectral domains. For this purpose, two multiblock methods, MB-PLS and S-PLS, were chosen. In a first step, PLS models were developed for each spectral range and results were compared on the basis of a statistical test. No significant difference was found for the prediction of resins and asphaltenes. On the contrary, for the prediction of saturate and aromatic contents, NIR performed better. In a second step, MIR and NIR spectral range were combined using MB-PLS and S-PLS. A significant improvement was obtained for the prediction of resin content using MB-PLS. In addition, the contributions of CH out of plane bending vibrations and aromatic CC stretching vibrations for the description of highly unsaturated compounds could be highlighted in MIR.

Variable temperature studies on mesogenic polythiophenes using 2D-IR and WAXS

We synthesized and investigated the molecular ordering of 4-{(E)-[(4-alkoxy phenyl imino] methyl} phenyl] thiophene-3-carboxylate (APTC) oligomers of varying alkoxy chain lengths using polarised Infrared spectroscopy (IR) and wide-angle X-ray scattering (WAXS). Infrared polarisation study shows maximum dichroic ratio for Phenyl CC stretching for Decyloxy (PDPTC) at room temperature. During heating C–O–C shows higher dichroic ratio in dodcecyloxy (PDDPTC) due to the restrains in the torsional angle and hindered rotation of it. By using temperature as perturbation, IR correlation (2D-IR) was performed. 2D-IR analysis results are classified into three parts. First, at phase temperature, CO splits into two peaks due to dipole–dipole interaction; second, chain bending in CH2 alkyl chain and variation in CH2 stretching with molecular environment and third, thiophene out of plane bending vibration shows main chain thiophene flipping with respect to alkoxy chain length. In addition to that, an intriguing evidence of liquid crystalline phase stability by CO dipole moment over alkyl chain is seen. 2D-IR analysis of thiophene region also shows “four-leaf clover pattern” on increasing alkoxy chain length and a change in phenyl group C–H in plane bending vibration along with it is evidenced. Hetero correlation between WAXS and IR shows interlayer packing variation with zigzag alignment for lower homologues and linear alignment for higher homologues with lower ‘d’ spacing value plotting with change in CH2 stretching vibration of alkoxy chain length.

Effect of taper ratio on parametric stability of a rotating tapered beam

Abstract Out-of-rotation plane bending vibrations of a rotating tapered beam with periodically varying speed are considered. The integro-partial differential equation of the beam is discretized via Galerkin's method and a set of ordinary differential equations with periodic coefficients (Mathieu–Hill type equations) is obtained. Dynamic stability of this parametrically excited system is studied via a monodromy matrix method, the effect of taper ratio on the stability of the system is examined and the results are presented in the form stability charts.

Characterization of SrCO3 and BaCO3 nanoparticles synthesized by cyclic microwave radiation

Uniform strontium carbonate (SrCO3) and barium carbonate (BaCO3) nanoparticles were successfully synthesized using alkaline earth metal nitrate (M(NO3)2 with M2+=Sr2+ and Ba2+) and sodium carbonate (Na2CO3) in ethylene glycol by a cyclic microwave radiation. The products were characterized by X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM) and selected area electron diffraction (SAED). In this research, the products were orthorhombic SrCO3 and BaCO3 phase with nanoparticles over the ranges of 20–50nm for SrCO3 and 40–100nm for BaCO3, including the detection of asymmetric C–O stretching, symmetric C–O stretching, out of plane bending and in plane bending vibrations at 1463, 1071, 862 and 708cm−1 for SrCO3, and 1439, 1059, 858 and 692cm−1 for BaCO3, respectively.

Characterization of SrCO 3 and BaCO 3 nanoparticles synthesized by sonochemical method

SrCO 3 and BaCO 3 nanoparticles were synthesized using Sr(NO 3) 2 or Ba(NO 3) 2 and Na 2CO 3 as starting materials in ethylene glycol by ultrasonic irradiation at 80 °C for 1–5 h. Their phases, vibration modes and morphologies were characterized using X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, selected area electron diffraction (SAED) and transmission electron microscopy (TEM). These products were found to be orthorhombic SrCO 3 and BaCO 3 nanoparticles with 20–50 nm and 40–100 nm ranges, respectively. Asymmetric stretching, symmetric stretching, and out of plane and in plane bending vibrations of CO 3 2− complexes were also detected.

Occurrence and distribution of metals and porphyrins in Nigerian coal minerals

The metal contents of Nigerian coal minerals were analyzed using an atomic absorption spectrophotometer. Calcium, Na and Fe occurred as major elements with concentrations ranging from 9782 μg/g for Ca to 432 μg/g for Na, whereas K, Mg, Mn, Ni, Cr, Zn, Pb and Cu, which occurred at trace levels ranged from 673.73 μg/g for Mg to 2.97 μg/g for Mn. Results of quantitative analysis of porphyrins extracted from the coal minerals showed that Onyeama coal has the highest amount of porphyrins (ca 0.96 μg/g) while Okpara has the lowest (ca 0.30 μg/g). The porphyrins were qualitatively characterized by a combination of thin layer chromatography (TLC), infrared and ultraviolet-visible spectrophotometers. The results of the mid infrared analysis (MIR) showed the presence of absorption bands at 3440–3450 and 1640–1680 cm −1 which are owing to stretching vibrations of N–H and C=C of aromatics, with C–H out of plane (oop) bending vibrations at wavenumbers less than 900 cm −1, all of which are characteristic absorptions of porphyrin free base. The ultraviolet-visible data showed prominent peaks at 400 nm (Soret band) and at wavelength ranges of 535–550 nm (β–band) and 565–600 nm (α–band) for the coal porphyrins analyzed. The geochemical significance of the metals and porphyrins in coal minerals are discussed.

<b>Infrared and ultraviolet spectrophotometric analysis of chromatographic fractions of crude oils and petroleum products</b>

Samples of light, medium and heavy Nigerian crude oils and petroleum products including diesel oil, engine oil (SAE 40) and gasoline (PMS) have been separated into four fractions of saturates, monoaromatics, diaromatics and polyaromatics by elution liquid chromatography. The fractions obtained were analysed using IR and UV-visible spectrophotometry. The infrared data confirmed the presence of methyl and methylene groups in the saturate fractions of the crude oils and petroleum products. The C=C stretching vibrations and C–H out of plane bending vibration of aromatics were also found in the mono-, di- and polyaromatics fractions. The characteristic UV spectra of alkyl benzenes and naphthalenes were observed in the monoaromatic and diaromatic fractions, respectively. The spectra of the polyaromatic fractions indicate the presence of anthracenes and phenanthrenes. KEY WORDS: Crude oils, Petroleum products, Diesel oil, Engine oil, Gasoline Bull. Chem. Soc. Ethiop. 2007, 21(1), 135-140.

Linearly coupled shaft-torsional and blade-bending vibrations in multi-stage rotor-blade systems

In an attempt towards the understanding of coupling effects between shaft-torsional and blade-(in plane) bending vibrations in turbomachinery and other rotating bladed structures, an idealized model is considered where the blades are represented by uniform Euler–Bernouilli beams. A synthetical, multi-frame and mixed (consisting in a coalescence of finite element and Galerkin methods) approach is used to derive a linearized mathematical model for the system. It is shown that the related eigenanalysis problem splits into two separate sub-problems corresponding to two kinds of possible normal mode motions. Eigenanalyses are performed concerning single as well as multi-stage rotor-blade system examples. Parametric studies are presented on the variation of the eigenfrequencies with system parameters. Eigenvalue loci veering phenomena are shown to occur, causing departure of the eigenvalues from those obtained through an uncoupled analysis. Mode shape examples are also presented.

Raman spectroscopic study of the uranyl tricarbonate mineral liebigite

Raman spectroscopy at 298 and 77 K has been employed to study the structure of the uranyl tricarbonates liebigite {Ca 2[UO 2(CO 3) 3]11H 2O}. The spectra of the samples are sample dependent and significant differences in the Raman spectra are obtained upon cooling to 77 K. It is proposed that the mineral undergoes a phase change upon cooling. Significant changes in the Raman spectra are observed in the hydroxyl stretching region and in the low wavenumber region. Two Raman bands are observed at 3468 and 3528 cm −1 showing the non-equivalence of the water units in the structure. Obtaining spectra at 77 K enables well resolved bands at 3530, 3501, 3482, 3463, 3443, 3405 and 3364 cm −1. Two well resolved bands at 1087 and 1073 cm −1 in the 298 K spectra become bands at 1093, 1076 and 1008 cm −1 in the 77 K spectrum proving the non-equivalence of the carbonate units. This non-equivalence is reflected in the observation of multiple bands in the carbonate bending regions. The (UO 2) 2+ units are characterised by the antisymmetric stretching vibrations at 902, 885 and 873 cm −1 and by the ν 2 bending modes at 248 cm −1. Two bands near 820 cm −1 may be assigned to the ν 1 (UO 2) 2+ symmetric stretching vibrations, however, a coincidence of these vibrations with the ν 2 (CO 3) 2− out-of plane bending vibrations cannot be excluded. The use of Raman spectroscopy enables a better definition of the vibrational modes of liebigite and shows changes in the molecular structure upon reaching 77 K.

Structure Analysis of Dipeptides in Water by Exploring and Utilizing the Structural Sensitivity of Amide III by Polarized Visible Raman, FTIR−Spectroscopy and DFT Based Normal Coordinate Analysis

A series of dipeptides AX and XA (X = G, K, L, S, and V) were investigated by polarized visible Raman and FTIR-spectroscopy to examine the conformational determinants of the amide III band. A spectral decomposition combined with density functional calculations revealed that the amide III band has a multicomponent structure in that three different modes contribute to amide III vibrations. One of them (amide III2) dominates the Raman spectra particularly of the cationic species. Its normal mode displays an in-phase combination of NH and Cα1H in plane bending vibrations, which makes it sensitive to changes of the dihedral angle ψ. Indeed, our Raman data show that amide III2 varies with ψ but remains practically unaffected by variation of φ in the region between −95° and −75°, which is sampled by the investigated AX peptides. Our data support the Lord hypothesis that amide III depends solely on ψ (Lord, R. Appl. Spectrosc. 1977, 31, 187) but specifies to which of the amide III modes this statement applies. Ou...

Interaction of internal water molecules with the schiff base in the L intermediate of the bacteriorhodopsin photocycle.

In the photocycle of bacteriorhodopsin (BR), the first proton movement, from the Schiff base to Asp85, occurs after the formation of the L intermediate. In L, the C [double bond] N bond of the Schiff base is strained, and the nitrogen interacts strongly with its counterion. The present study seeks to detect the interaction of internal water molecules with the Schiff base in L using difference FTIR spectroscopy at 170 K. The coupled modes of the hydrogen-out-of plane bending vibrations (HOOPs) of the N-H and C(15)-H of the protonated Schiff base are detected as a broad band centered at 911 cm(-1) for BR. A set of bands at 1073, 1064, and 1056 cm(-1) for L is shown to arise from the coupling of the HOOP with the overtones of interacting water O-H vibrations. Interaction with water was shown by the decreased intensity of the HOOPs of L in H(2)(18)O and by the influence of mutants that have been shown to perturb specific internal water molecules in BR. In contrast, the HOOP band of initial BR was not affected by these mutations. In D85N, the coupled HOOP of BR is depleted, while the coupled HOOPs of L are shifted. The results indicate that the Schiff base interacts with water in the L state but in a different manner than in the BR state. Moreover, the effects of mutations suggest that cytoplasmic water close to Thr46 (Wat46) either interacts stronger with the Schiff base in L or that it is important in stabilizing another water that does.