Search results for: A.P. Ayala

Items from 1 to 20 out of 48 results

article

Crystal structure, vibrational spectra and quantum chemical parameters of 2-hydroxy-3,4,6-trimethoxyacetophenone isolated from the Croton anisodontus Müll. Arg. (Euphorbiaceae)

R.N.S. Santiago, P.T.C. Freire, A.P. Ayala, A.M.R. Teixeira, more

Journal of Molecular Structure > 2018 > 1171 > C > 815-826

In this paper the isolation of 2-Hydroxy-3,4,6-trimethoxyacetophenone (C₁₁O₅H₁₄) from the stem bark of Croton anisodontus Müll. Arg. (Euphorbiaceae) is presented and its structure is characterized using Nuclear Magnetic Resonance and single crystal X-ray diffraction. The crystalline structure of this natural compound, which presents potential antimicrobial activity, was determined at 100 K and 298 K...

article

Use of Comprehensive Geriatric Assessment and Geriatric Screening for Older Adults in the Radiation Oncology Setting: A Systematic Review

E. Szumacher, S. Sattar, M. Neve, K. Do, more

Clinical Oncology > 2018 > 30 > 9 > 578-588

Comprehensive geriatric assessment (CGA) is a multidisciplinary diagnostic process that evaluates medical, psychological, social and functional capacity. No systematic review of the use of CGA in radiation oncology has been conducted. This paper reviews the use of CGA in radiation oncology, examines whether such assessments are feasible and evaluates the effectiveness of these assessments in predicting...

article

A combined experimental (IR, Raman and UV–Vis) and quantum chemical study of canadine

Bhawani Datt Joshi, Anubha Srivastava, Poonam Tandon, Sudha Jain, more

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy > 2018 > 191 > C > 249-258

Plant based natural products cover a major sector of the medicinal field, as such focus on plant research has been increased all over the world. As an attempt to aid that research, we have performed structural and spectroscopic analysis of a natural product, an alkaloid: canadine. Both ab initio Hartree-Fock (HF) and density functional theory (DFT) employing B3LYP using 6-311++G(d,p) basis set were...

article

Spectroscopic (far or terahertz, mid-infrared and Raman) investigation, thermal analysis and biological activity of piplartine

Anubha Srivastava, T. Karthick, B.D. Joshi, Rashmi Mishra, more

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy > 2017 > 184 > C > 368-381

Research in the field of medicinal plants including Piper species like long pepper (Piper longum L.- Piperaceae) is increasing all over the world due to its use in traditional and Ayurvedic medicine. Piplartine (piperlongumine, 5,6-dihydro-1-[(2E)-1-oxo-3-(3,4,5-trimethoxyphenyl)-2-propenyl]-2(1H)-pyridinone), a biologically active alkaloid/amide was isolated from the phytochemical investigations...

article

Study of Cr→SmA phase transition and hydrogen bonding in four-ring bent-core liquid crystal

Swapnil Singh, Harshita Singh, Poonam Tandon, Nirmalangshu Chakraborty, more

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy > 2017 > 178 > C > 142-150

A newly designed asymmetrical four-ring bent-core compound (4′-n-decyloxyphenylazo)-phenyl-4-yl-3-[N-(4′-n-octadecyloxy-2-hydroxybenzylidene) amino]-2-methyl benzoate exhibiting liquid crystalline behavior was synthesized and characterized. The thermal and textural morphology were studied using differential scanning calorimetry and polarizing optical microscopy, respectively. The study of hydrogen...

article

Temperature-dependent infrared study of phase transitions in bent-core liquid crystalline compound 12O(OH)2MeO10

Swapnil Singh, Harshita Singh, Poonam Tandon, N.V.S. Rao, more

Vibrational Spectroscopy > 2017 > 90 > C > 38-45

Temperature-dependent Fourier-transform infrared (FTIR) investigation on a novel four-ring bent-core liquid crystal ((4′-n-decyloxyphenylazo)-phenyl-4-yl-3-[N-(4′-n-dodecyloxy-2-hydroxybenzylidene) amino]-2-methyl benzoate) has been done to study the dynamics of the molecules in mesophases at the molecular level. The spectroscopic analysis revealed that specific modes gave a clear evidence of Cr⇄SmC...

article

Study of phase transitions in a bent-core liquid crystal probed by infrared spectroscopy

Swapnil Singh, Harshita Singh, Anubha Srivastava, Poonam Tandon, more

Vibrational Spectroscopy > 2016 > 86 > C > 24-34

A new four ring bent-core liquid crystal (4′-n-octylphenylazo)-phenyl-4-yl-3-[N-(4′-n-dodecyloxy-2-hydroxybenzylidene) amino]-2-methyl benzoate has been synthesized and investigated using differential scanning calorimetry (DSC), polarized optical microscopy (POM) and temperature-dependent Fourier transform infrared (TD-FTIR) spectroscopy. DSC and POM were used to detect transition temperatures and...

article

The temperature-dependent single-crystal Raman spectroscopy of a model dipeptide: l-Alanyl-l-alanine

J.G. Silva, L.M. Arruda, G.S. Pinheiro, C.L. Lima, more

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy > 2015 > 148 > Complete > 244-249

A single-crystal of peptide l-alanyl-l-alanine (C ₆ H ₁₂ N ₂ O ₃ ) was studied by Raman spectroscopy at low-temperature, and a tentative assignment of the normal modes was given. Evidence of a second order structural phase transition was found through Raman spectroscopy between the temperatures of 80K and 60K. Group theory considerations suggest that the transition...

article

Structural, hyperfine and Raman properties of RE2FeSbO7 compounds

G. Berndt, K.L. Silva, F.F. Ivashita, A. Paesano, more

Journal of Alloys and Compounds > 2015 > 618 > C > 635-642

Pyrochlores of the RE₂FeSbO₇ type were synthesized by ball-milling followed by annealing in free atmosphere at high temperatures. The samples prepared were characterized by X-ray diffraction, Raman spectroscopy and ⁵⁷Fe Mössbauer spectroscopy, at room temperature. The results showed that RE₂FeSbO₇ compounds have a cubic structure, i.e., Fd-3m (#227) space group, and that a site disorder takes place...

article

Study of molecular structure, vibrational, electronic and NMR spectra of oncocalyxone A using DFT and quantum chemical calculations

Bhawani Datt Joshi, Anubha Srivastava, Sara Braga Honorato, Poonam Tandon, more

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy > 2013 > 113 > Complete > 367-377

Oncocalyxone A (C ₁ ₇ H ₁ ₈ O ₅ ) is the major secondary metabolite isolated from ethanol extract from the heartwood of Auxemma oncocalyx Taub popularly known as ''pau branco''. Oncocalyxone A (Onco A) has many pharmaceutical uses such as: antitumor, analgesic, antioxidant and causative of inhibition of platelet activation. We have performed the optimized geometry,...

article

Structural characterization of bismuth rare earth tungstates obtained by fast microwave-assisted solid-state synthesis

G.N. Rocha, L.F.L. Melo, M.C. Castro, A.P. Ayala, more

Materials Chemistry and Physics > 2013 > 139 > 2-3 > 494-499

A new synthetic route was used to obtain bismuth rare earth tungstates: BiREWO ₆ , where RE = Y, Gd and Nd. These materials were obtained by microwave radiation in air at 900–1100 °C for 10 min, depend on the rare earth composition in the ceramic. Structural characterization was performed by X-ray powder diffraction, Infrared and Raman spectroscopy. It was observed that all samples are isostructural...

article

Raman spectra of Ga3PO7 single crystal

Nana Zhang, Jiyang Wang, Guogang Xu, Yongjie Guo, more

Materials Letters > 2013 > 98 > Complete > 258-260

The room temperature phonon modes of trigallium phosphorus heptaoxide (Ga ₃ PO ₇ ) single crystal have been determined by polarized Raman spectroscopy. The Ga ₃ PO ₇ single crystal exhibits a trigonal structure belonging to the space group R3m (C3v5) with three molecules per unit cell (Z=3). The framework structure of the Ga ₃ PO ₇ crystal consists of...

article

Room-temperature vibrational properties of the BiMn2O5 mullite

F.M. Silva Júnior, C.W.A. Paschoal, R.M. Almeida, R.L. Moreira, more

Vibrational Spectroscopy > 2013 > 66 > Complete > 43-49

Raman and infrared spectroscopic measurements were performed and combined with lattice dynamics simulations in order to describe the room temperature vibrational properties of the BiMn ₂ O ₅ mullite ceramic. A total of 13 Raman active modes and 19 infrared active modes were observed. The lattice dynamics simulation was used to assign the observed bands and to discuss the phonon behavior...

article

Study of polymorphism in imatinib mesylate: A quantum chemical approach using electronic and vibrational spectra

Anubha Srivastava, B.D. Joshi, Poonam Tandon, A.P. Ayala, more

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy > 2013 > 103 > Complete > 325-332

Imatinib mesylate, 4-(4-methyl-piperazin-1-ylmethyl)-N-u[4-methyl-3-(4-pyridin-3-yl)pyrimidine-2-ylamino)phenyl]benzamide methanesulfonate is a therapeutic drug that is approved for the treatment of chronic myelogeneous leukemia (CML) and gastrointestinal stromal tumors (GIST). It is known that imatinib mesylate exists in two polymorphic forms α and β. However, β-form is more stable than the α-form...

article

Preparation and Study of Bismuth Rare-Earth Tungstate Composite Screen-Printed Thick Films

G.N. Rocha, L.F.L. Melo, S.M. Dantas, A.P. Ayala, more

Journal of Electronic Materials > 2013 > 42 > 4 > 752-760

In this paper, we report the microstructural and dielectric properties of bismuth rare-earth tungstate composite screen-printed thick films (BiGd_1−X Nd_XWO₆, BiGd_1−XY_XWO₆, and BiY_1−XNd_XWO₆). The crystal structure of BiREWO₆ (RE = Gd, Nd, and Y) can be associated with the Bi₂WO₆ perovskite structure. It was observed that the crystalline structure was attributed to a monoclinic phase with space...

article

Temperature-dependent Raman spectra of Bi2Sn2O7 ceramics

R.X. Silva, C.W.A. Paschoal, R.M. Almeida, M. Carvalho Castro, more

Vibrational Spectroscopy > 2013 > 64 > Complete > 172-177

The Bi ₂ Sn ₂ O ₇ pyrochlore is known to undergo a sequence of structural phase transitions with an increase in temperature. Raman spectroscopy was employed in the investigation of the temperature dependence of the active phonons in the Raman spectrum. We observed 19 broad modes at room temperature, reflecting the low symmetry of the α-phase of Bi ₂ Sn ₂ O ...

article

Optical phonon features in ferroelectric Bi3Fe1/2Nb3/2O9

A. Nonato, C.W.A. Paschoal, E.N. Silva, A.P. Ayala, more

Vibrational Spectroscopy > 2012 > 63 > Complete > 409-417

We have investigated the Raman scattering and infrared active optical phonons in Bi ₃ Fe _1/2 Nb _3/2 O ₉ . At room temperature the phonons were assigned according to lattice dynamic calculations performed using the Wilson's FG method. The infrared phonon parameters allowed us to calculate the real part of the dielectric permittivity and losses in the far infrared region,...

article

Physicochemical properties and thermal stability of quercetin hydrates in the solid state

G.S. Borghetti, J.P. Carini, S.B. Honorato, A.P. Ayala, more

Thermochimica Acta > 2012 > 539 > Complete > 109-114

In the present work three samples of quercetin raw materials (QCTa, QCTb and QCTc), purchased from different Brazilian suppliers, were characterized employing scanning electron microscopy, Raman spectroscopy, simultaneous thermogravimetry and infrared spectroscopy, differential scanning calorimetry, and variable temperature-powder X-ray diffraction, in order to know their physicochemical properties,...

article

Study on the structure and vibrational spectra of efavirenz conformers using DFT: Comparison to experimental data

Soni Mishra, Poonam Tandon, A.P. Ayala

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy > 2012 > 88 > Complete > 116-123

Efavirenz, (S)-6-chloro-4-(cyclopropylethynyl)-1,4-dihydro-4-(trifluoromethyl)-2H-3,1-benzoxazin-2-one, is an anti HIV agent belonging to the class of the non-nucleoside inhibitors of the HIV-1 virus reverse transcriptase. A systematic quantum chemical study of the possible conformations, their relative stabilities and vibrational spectra of efavirenz has been reported. Structural and spectral characteristics...

article

Tapes of water hexamer clusters in the interlayer space of a 2D MOF: Structural, spectroscopic and computational insight of the confined water

M.C. Bernini, E.V. Brusau, G.E. Narda, G. Echeverria, more

Polyhedron > 2012 > 31 > 1 > 729-737

The synthesis, crystal structure and characterization of [Er ₂ (C ₄ H ₄ O ₄ ) ₃ (H ₂ O) ₄ ]·6H ₂ O, with particular emphasis on the structural details and the vibrational behavior of the highly organized sub-net of water are reported. X-ray structural analysis reveals that the hybrid framework, which can be classified as belonging to...

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Search results for: A.P. Ayala

Crystal structure, vibrational spectra and quantum chemical parameters of 2-hydroxy-3,4,6-trimethoxyacetophenone isolated from the Croton anisodontus Müll. Arg. (Euphorbiaceae)

Use of Comprehensive Geriatric Assessment and Geriatric Screening for Older Adults in the Radiation Oncology Setting: A Systematic Review

A combined experimental (IR, Raman and UV–Vis) and quantum chemical study of canadine

Spectroscopic (far or terahertz, mid-infrared and Raman) investigation, thermal analysis and biological activity of piplartine

Study of Cr→SmA phase transition and hydrogen bonding in four-ring bent-core liquid crystal

Temperature-dependent infrared study of phase transitions in bent-core liquid crystalline compound 12O(OH)2MeO10

Study of phase transitions in a bent-core liquid crystal probed by infrared spectroscopy

The temperature-dependent single-crystal Raman spectroscopy of a model dipeptide: l-Alanyl-l-alanine

Structural, hyperfine and Raman properties of RE2FeSbO7 compounds

Study of molecular structure, vibrational, electronic and NMR spectra of oncocalyxone A using DFT and quantum chemical calculations

Structural characterization of bismuth rare earth tungstates obtained by fast microwave-assisted solid-state synthesis

Raman spectra of Ga3PO7 single crystal

Room-temperature vibrational properties of the BiMn2O5 mullite

Study of polymorphism in imatinib mesylate: A quantum chemical approach using electronic and vibrational spectra

Preparation and Study of Bismuth Rare-Earth Tungstate Composite Screen-Printed Thick Films

Temperature-dependent Raman spectra of Bi2Sn2O7 ceramics

Optical phonon features in ferroelectric Bi3Fe1/2Nb3/2O9

Physicochemical properties and thermal stability of quercetin hydrates in the solid state

Study on the structure and vibrational spectra of efavirenz conformers using DFT: Comparison to experimental data

Tapes of water hexamer clusters in the interlayer space of a 2D MOF: Structural, spectroscopic and computational insight of the confined water

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