Spectroscopic analysis of irradiated erythrocytes

The aim of the present work is to study the effect of gamma radiation on the lipid part of the erythrocyte membrane, and to test the efficiency of lipoic acid as a radioprotector. This effect was evaluated using electron paramagnetic resonance (EPR), and Fourier transform infrared (FT-IR) spectroscopy. The results showed an increase in the number of spin density by 14%, 22% and 65% after exposure to 25, 50 and 100 Gy respectively; whereas there was a decline in the obtained density after incubation with lipoic acid by a factor of approximately 32%. The FT-IR spectra of the irradiated erythrocytes samples showed a marked decrease in the intensity of all characteristic peaks, which increased as the irradiation dose increased. The second-derivative of these spectra, allow the conformationally sensitive membrane acyl chain methylene stretching modes to be separated from the protein (mostly hemoglobin) vibrations that dominate the spectra of intact cells. The 2850 cm⁻¹ band showed changes in the band shape and position after exposure to 50 and 100 Gy. Therefore it can be concluded that the band at 2850 cm⁻¹ only is useful in monitoring the radiation effect of the lipids cell membrane intact cells.     

Thermal study of four irradiated imidazoline derivatives in solid state

Four imidazoline derivatives: antazoline (AN), naphazoline (NN), tymazoline (TM), xylometazoline (XM), in the form of hydrochlorides in solid phase have been subjected to high energy e-beam irradiation from an accelerator (~10 MeV) at a dose varied from 25 to 200 kGy. The effects of the irradiation have been assessed by DSC, X-ray diffraction, FTIR, EPR and TLC. The standard sterilisation dose of 25 kGy has been found to produce changes in the properties of one derivative (XM), two other ones (AN and TM) have been found sensitive to doses >100 kGy, whereas NN has been resistant to irradiation in the whole range studied (25–200 kGy). EPR results indicated that the changes taking place in the therapeutic substances studied are related to radical formation. The irradiation induced changes in colour, a decrease or increase in the melting point, changes in the XRD pattern, small changes in the shape of FTIR peaks and the presence of radiolysis products. The XM compounds cannot be sterilised by irradiation because of the radiation induced changes in its physico-chemical properties.     

Spectroscopic investigation of the interaction of p-benzoquinone with casein in the solid state

The reaction between p-benzoquinone (PBQ) and casein (protein) in the solid state was studied. After reaction with protein, the FT-IR spectra showed a new band at 1215 cm^?1, with an intense sign attributed for casein/PBQ product. An optimum amount of PBQ for determination of the product when mixed with casein was 100 mg and a reaction time of 30 min. The product was stable for a period of 24 h after the reacting by heating. The interaction of PBQ with casein was investigated by FT-IR, reflectance, Raman and EPR spectroscopies. The reaction between PBQ and casein in the solid state yields a radical species (p-benzosemiquinone) that it is stabilized by the presence of p-biphenolate and p-benzoquinone species in the solid state.     

Isoconversional analysis of solid state transformations

There are many mathematical methods to determine the activation energy from non-isothermal experiments. However, controversies arise over the different values obtained by these methods. We will show that the origin of these discrepancies is either inaccurate approximations of the so-called temperature integral or the occurrence of complex transformations. We will review and compare the most commonly used methods. For those methods that lack accuracy, we will introduce simple numerical modifications to make them exact. In addition, we will introduce a new method that allows easy and accurate determination of the activation energy.     

Isoconversional analysis of solid state transformations

We will analyze the discrepancies between isoconversional methods when applied to complex transformations. The practical analysis of particular transformations leads us to conclude that (a) conventional integral methods based on integrated equations are essentially incorrect when dealing with variable activation energy; and (b) experimental inaccuracies and noise tend to give an apparent evolution of the energy variation, so that, non-constancy of the activation energy does not necessarily mean deviations from single-step transformations with constant activation energy.     

Spectroscopic manifestations of charge separation in the organic solid state: a UPS study of zwitterionic glycine

Results of vapor- and condensed-phase UPS measurements and CNDO/S computations are used to address the modifications to the ordering of glycine orbitals due to charge separation upon conversion from the free molecule to the zwitterionic solid-state conformation.     

Spectroscopic study of gamma irradiated bovine hemoglobin

In the present study, the effects of ionizing radiation of Cs-137 and Co-60 from 4.95 to 743.14 Gy and from 40 Gy to 300 kGy, respectively, on some bovine hemoglobin characteristics were studied. Such an effect was evaluated using electron paramagnetic resonance (EPR) spectroscopy, and infra-red (IR) spectroscopy. Bovine hemoglobin EPR spectra were recorded and analyzed before and after irradiation and changes were explained in detail. IR spectra of unirradiated and irradiated Bovine hemoglobin were recorded and analyzed also. It was found that ionizing radiation may lead to the increase of free radicals production, the decrease in α-helices contents, which reflects the degradation of hemoglobin molecular structure, or at least its incomplete performance. Results also show that the combined application of EPR and FTIR spectroscopy is a powerful tool for determining structural modification of bovine hemoglobin samples exposed to gamma irradiation.     

Spectroscopic properties of lanthanoid benzene carboxylates in the solid state: Part 2. Polar substituted benzoates

Europium and terbium complexes of ortho, meta and para substituted benzoate ligands including nitrobenzoate (NBA), aminobenzoate (ABA), hydroxybenzoate (OHBA) and methoxybenzoate (MeOBA) have been synthesised by metathesis reactions, carried out in aqueous media. The complexes were characterised by elemental, compositional and structural investigations, including microanalysis, EDTA titrations, differential thermal analysis, infra red spectroscopy, X-ray powder diffraction and single crystal structural analyses. Besides this, strong emphasis was on the determination of the optoelectronic properties of the compounds in the solid state. In this regard, reflectance, excitation and emission spectra were recorded. From these, the emission and excitation efficiencies were determined. The relative intensities as well as the splitting patterns of the ⁵D₀ → ⁷F_J transitions in the europium emission spectra are discussed.     

Spectroscopic study of solid state photoreaction of di n-propyl ester of dicyano p-phenylenediacrylic acid

Photopolymerization reaction in di n-propyl ester of dicyano p-phenylene diacrylic acid crystal is shown to be mediated by exciton–phonon coupling. Raman phonon spectra suggest that at the initial stage of reaction progress, the reactant and the product form a solid solution. In the later stage, the reactant segregates out and forms its own lattice. The polymer lattice is shown to maintain a good degree of order. Infrared and Raman spectra confirm that the polymerization occurs by cyclobutane ring formation. © 1994 John Wiley & Sons, Inc.     

New solid state NMR techniques in coal analysis

Nuclear magnetic resonance (NMR) spectroscopy has become a valuable technique for the determination of the aromaticity of fossil fuels. Now, by exploiting ¹³C relaxation, intimate details of the structure of coal may be determined. This article briefly describes these new applications.     

Solvent free reactions in the solid state: solid state metathesis

Transition Metal Chemistry -     

Spectroscopic studies of iron(III) complexes of D-saccharose and D-glucose in the solid state and in solution

Iron(III) complexes of D-saccharose and D-glucose were prepared. The compositions of the complexes were determined by standard analytical methods. The Mössbauer spectra reflected the presence of high-spin iron(III) in the polynuclear species. EPR spectroscopy demonstrated antiferromagnetically coupled iron(III) centers within the solid complexes. The¹³C NMR spectra indicated the presence of a mixture of coordination isomers of iron(III) complexes containing the sugar ligand in differently bound forms.This work is dedicated to the memory of Dr. L. Korecz.     

Spectroscopic and structural characterization of the CyNHC adduct of B2pin2 in solution and in the solid state

The Lewis base adduct of B(2)pin(2) and the NHC (1,3-bis(cyclohexyl)imidazol-2-ylidene), which was proposed to act as a source of nucleophilic boryl groups in the β-borylation of α,β-unsaturated ketones, has been isolated, and its solid state structure and solution behavior was studied. In solution, the binding is weak, and NMR spectroscopy reveals a rapid exchange of the NHC between the two boron centers. DFT calculations reveal that the exchange involves dissociation and reassociation of NHC rather than an intramolecular process.     

Kinetic and thermodynamic analysis of degradation of doripenem in the solid state

The kinetic and thermodynamic parameters of degradation of doripenem were studied using a high‐performance liquid chromatography method. In dry air, the degradation of doripenem was a first‐order reaction depending on the substrate concentration. At increased relative air humidity, doripenem was degraded according to the autocatalysis kinetic model. The dependence ln k = f1/T) was described by the equations ln k = 5.10 ± 13.06 ? (7576 ± 4939)(1/T) in dry air and ln k = 46.70 ± 22.44 ? (19,959 ± 8031)(1/T) at 76.4% relative humidity (RH). The thermodynamic parameters E_a, ΔH^≠a, and ΔS^≠a of the degradation of doripenem were calculated. The dependence ln k = f (RH%) was described by the equation ln k = (0.155 ± 0.077) × 10^?1 (RH%) ? (3.45 ± 21.8) × 10^?10. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 44: 722–728, 2012     

FTIR assessment of poly(ethylene oxide) irradiated in solid state,melt and aqeuous solution

FTIR spectroscopy was used to study poly(ethylene oxide), PEO, irradiated in solid and molten aggregate states and as aqueous solutions of various concentrations. The changes in shape and width of –C–O–C– complex absorption intensities at around 1112 cm^?1 were the most prominent. On irradiation of solid samples in contact with air shrinking of –C–O–C– complex and increase in its absorption intensities indicated predominant degradation. Crosslinking prevailed on irradiation of molten PEO and of its aqueous solutions in nitrogen atmosphere and manifested itself as widening of –C–O–C– absorption and decrease of corresponding intensities. Partial or complete merging of CH₂ wagging vibrations at 1342 cm^?1 and 1360 cm^?1 that are characteristic of crystalline PEO into a single absorption at around 1350 cm^?1 indicated amorphization what was observed for samples that had reduced degree of crystallinity determined by differential scanning calorimetry. DSC could not discriminate between degradation and crosslinking while the changes in width and shape of –C–O–C– complex were independent of the changes in crystallinity. Comparison of FTIR spectra of the same PEO samples obtained as thin film and as KBr pellets revealed that pellet preparation results in a number of spectral artefacts.     

Nanotechnology – a challenge for solid state analysis

The characterisation of nanoscaled structures is an essential part of nanotechnology. Using nanoscaled Co/Cu multilayers as an example of magnetoelectronic devices, the dependence of the layer formation mechanism on the deposition method (pulsed laser deposition and sputtering) is shown. The evolution of the thermal deterioration of Co (2 nm)/Cu (2 nm) multilayers during annealing can be understood using a combination of Monte-Carlo simulations and observations of intermediate steady states. It is shown that analytical TEM, especially energy-filtered imaging, is excellently qualified for this kind of characterisation.     

Hydrogen molecules trapped in irradiated solid ethanol

Raman spectroscopy of γ-irradiated solid ethanol at 77 K revealed that trapped H₂ is produced mainly by the H atom abstraction at the alkyl group by H radicals which are dissociated from the alkyl group of ethanol. Comparison of the peak wavenumbers and the band widths of H₂ between the glassy and crystalline phases of ethanol suggests that the trapping sites of H₂ in the glassy phase are smaller in the average size and less homogeneous in the size distribution. The molar ratio between ortho- and para-H₂ trapped in irradiated crystalline ethanol is in rough agreement with the thermodynamic equilibrium between 5–120 K, intimating that the ortho-para conversion is allowed under the existence of an electro-magnetic gradient due to paramagnetic radicals.     

Spectroscopic study of silver state in CaO

Electron spectra of the oxidized states of silver (Ag²⁺) in CaO have been identified by comparison of ESR and diffuse reflectance electron spectra.

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Ag²⁺ CaO .

     

Vibrational analysis and solid state conformation of monothiobiuret hydrate

The i.r. assignments for monothiobiuret(Mtb)-hydrate and its deuterated compound have been made from normal coordinate analyses carried out for Mtb and Mtb-d₅ using a chosen molecular model containing a trans-cis —CONHCS— group for Mtb (H₂NCONHCSNH₂). The i.r. spectra of anhydrous Mtb in solid and in solution and of Mtb · H₂O at liquid nitrogen temperature have also been studied.     

Depth profiles and resolution limits in accelerator-based solid state analysis

A ubiquitous problem in solid state analysis is the determination of the elemental composition of a sample as a function of the depth. The determination of the depth profiles from ion-beam experiments is an ill-posed inversion problem due to ion-beam and detector-induced energy spreads as well as energy-loss straggling and small-angle scattering effects. The inversion problem is solved in the framework of Bayesian probability theory, which provides a method for quantifying and combining uncertain data and uncertain additional information. By deconvolving the apparatus transfer function and modeling the scattering events in the sample we reconstructed depth profiles of (13)C in tetrahedral amorphous carbon (ta-C) and depth profiles in (12)C/(13)C marker probes. An enhancement of the energy resolution by a factor of 6 was obtained.