Search results for "RAMAN"
showing 10 items of 1328 documents
Synthesis and low-frequency vibrational spectra of some halo- and pseudohalo-diphenylantimonates(V)
1976
Abstract The syntheses of diphenylantimonates(V) of the type M(I) [PH 2 XbX 4 ] (M(I) = PH 4 As; X = F, Cl, Br, N 3 , NCS; X 4 = Cl 3 Br, Cl 3 N 3 ) are described. Far-Ir spectra of these compounds and of previously synthesized M(I) [Ph 2 SbCl 3 X] species (M(I) = Me 4 N; X = Cl, Br, N 3 ; M(I) = Ph 4 As; X = NCS) are reported. Raman spectra of tetrafluoro and tetrachloro salts are also given. Vibrational data are interpreted in terms of the presence of solid of trans -Ph 2 SbX 4 - species and assignments of skeletal modes are suggested.
Organoelement derivatives of steroids: synthesis and structural characterization of diorganotin chloride adducts of hormones
1986
Abstract Ten new diorganotin dichloride adducts of hormones of the type R 2 SnCl 2 ·2L [where R = Me, Et, n-Bu, Oct and Ph; L = 4-androsten-17s-ol-3-one ( A ); 5-androsten-3s-ol-17-one ( B ); 4-androsten-17α- methyl-17s-ol-3-one ( C ) and 3,17-dihydroxy-5- pregnene-20-one ( D )] have been prepared and characterized at 297 K and 223 K. Spectroscopic measurements (IR; Raman; 1 H, 13 C, 119 Sn NMR) suggest the dissociation or fast ligand exchange in solution at 297 K. Hexa-coordinated adducts with bonding through carbonyl oxygen and trans -R groups in octahedral geometry are formulated at 223 K.
New Alternative in the Methodology of Extraction and Dyeing with Active Molecules Derived from Vegetal Sources
2016
Abstract The general objective of this study refers to the identification of a sustainable and physical methodology of extraction of active compounds, envisaging the preservation of the high purity active natural dye molecule from nut shell (juglone), even under the conditions of an extraction performed in a mixt solvent medium (water-ethanol). The second major objective of the study consists of the application of these above mentioned dyes onto natural and synthetic substrates, thus making a correlation between their colour attributes and the fibrous composition of the substrates they are applied on. The motivation of this research was given by the identification of an improved extraction …
Studies of Reversible Hydrogen Binding in Nano- Sized Materials
2015
Experimental review of materials suitable for reversible hydrogen binding in nanoporous and nanosized structures of materials, based on natural zeolite (clinoptilolite) and graphene (exfoliated electrochemically from raw graphite), were analyzed. Characterization of materials with SEM, XRD, EDS and Raman spectroscopy methods and aspects of synthesis of a nanostructured zeolite and a few-layer graphite material was done in this work. It was established from gas analyzer results that hydrogen mass fraction in natural zeolite ranged from 1.1 % to 1.4 %, but in the few-layer graphite material − from 0.39 % to 0.46 %.
Lipid Droplets: A New Player in Colorectal Cancer Stem Cells Unveiled by Spectroscopic Imaging
2015
Abstract The cancer stem cell (CSC) model is describing tumors as a hierarchical organized system and CSCs are suggested to be responsible for cancer recurrence after therapy. The identification of specific markers of CSCs is therefore of paramount importance. Here, we show that high levels of lipid droplets (LDs) are a distinctive mark of CSCs in colorectal (CR) cancer. This increased lipid content was clearly revealed by label-free Raman spectroscopy and it directly correlates with well-accepted CR-CSC markers as CD133 and Wnt pathway activity. By xenotransplantation experiments, we have finally demonstrated that CR-CSCs overexpressing LDs retain most tumorigenic potential. A relevant con…
Sorting of Single Biomolecules based on Fourier Polar Representation of Surface Enhanced Raman Spectra
2016
AbstractSurface enhanced Raman scattering (SERS) spectroscopy becomes increasingly used in biosensors for its capacity to detect and identify single molecules. In practice, a large number of SERS spectra are acquired and reliable ranking methods are thus essential for analysing all these data. Supervised classification strategies, which are the most effective methods, are usually applied but they require pre-determined models or classes. In this work, we propose to sort SERS spectra in unknown groups with an alternative strategy called Fourier polar representation. This non-fitting method based on simple Fourier sine and cosine transforms produces a fast and graphical representation for sor…
Robustness of 40 Gb/s ASK modulation formats in the practical system infrastructure.
2006
In this work, we analyzed by means of numerical and laboratory experiments the resilience of 40 Gb/s amplitude shift keying modulation formats to transmission impairments in standard single-mode fiber lines as well as to optical filtering introduced by the optical add/drop multiplexer cascade. Our study is a pre-requisite to assess the implementation of cost-effective 40 Gb/s modulation technology in next generation high bit-rate robust optical transport networks. © 2006 Optical Society of America.
Multi-level optimization of a fiber transmission system via nonlinearity management
2006
Nonlinearity management is explored as a complete tool to obtain maximum transmission reach in a WDM fiber transmission system, making it possible to optimize multiple system parameters, including optimal dispersion pre-compensation, with fast simulations based on the continuous-wave approximation. © 2006 Optical Society of America.
Ambient-temperature high-pressure-induced ferroelectric phase transition in CaMnTi2O6
2017
Physical review / B 96(9), 094101 (2017). doi:10.1103/PhysRevB.96.094101
The effect of Cu substitution on the A1g mode of La(0.7)Sr(0.3)MnO3 manganites
2003
We report on the first Raman data of Cu substituted La(1-y)Sr(y)Mn(1-x)Cu(x)O3 (0 < x < 0.10 and 0.17 < y < 0.3, accordingly in order to have the same Mn(4+)/[Mn(4+)+Mn(3+)] ratio), collected in the frequency range 100-900 cm-1 and at room temperature, with parallel and crossed polarizations of the incident and scattered light. Spectra were fitted with a Drude-Lorentz model, and peaks at 190-220 and 430 cm-1, together with two broad structures centered at near 500 and 670 cm-1, have been found. We also have observed that the A1g mode is substantially shifted with increasing Cu substitution. The A1g phonon shift is a linear function of the tolerance factor t and the rhombohedral …