R. Moreh

Diagnosis of Cell Death by Means of Infrared Spectroscopy

Fourier transform infrared (FTIR) spectroscopy has been established as a fast spectroscopic method for biochemical analysis of cells and tissues. In this research we aimed to investigate FTIRs utility for identifying and characterizing different modes of cell death, using leukemic cell lines as a model system. CCRF-CEM and U937 leukemia cells were treated with arabinoside and doxorubicin apoptosis inducers, as well as with potassium cyanide, saponin, freezing-thawing, and H(2)O(2) necrosis inducers. Cell death mode was determined by various gold standard biochemical methods in parallel with FTIR-microscope measurements. Both cell death modes exhibit large spectral changes in lipid absorbance during apoptosis and necrosis; however, these changes are similar and thus cannot be used to distinguish apoptosis from necrosis. In contrast to the above confounding factor, our results reveal that apoptosis and necrosis can still be distinguished by the degree of DNA opaqueness to infrared light. Moreover, these two cell death modes also can be differentiated by their infrared absorbance, which relates to the secondary structure of total cellular protein. In light of these findings, we conclude that, because of its capacity to monitor multiple biomolecular parameters, FTIR spectroscopy enables unambiguous and easy analysis of cell death modes and may be useful for biochemical and medical applications.

Effect of molecular binding on the resonance scattering of photons from the 6.324 MeV level in 15N

Abstract The temperature effect of nuclear resonance scattering from the 6.324 MeV level in 15 N was studied as a function of temperature using a gaseous 15 N 2 target and a solid Li 15 NO 3 target. The γ-source was produced by the Cr(n, γ) reaction using thermal neutrons. In order to reproduce the experimental variation of the scattering cross section versus temperature, the Lamb treatment for metallic elements was generalised to the case of diatomic and more complicated molecules. In 15 N 2 an effective temperature was defined in which the zero-point energy of vibration of the diatomic molecule was included. In LiNO 3 , an effective temperature was also defined by introducing a modified Debye temperature and accounting for the normal modes of vibration of 15 N in the 15 NO 3 − molecule. An excellent agreement between measured and calculated values was obtained. In a way, the present measurement may be viewed as detecting the zero-point vibrations in molecules.

Properties of nuclear levels photoexcited by neutron-capture γ-rays of Ti and Cu

Abstract Neutron capture γ-rays of Ti and Cu have been used to photoexcite nuclear levels in the 5–8 MeV region in various nuclei. The spins, parities, and radiative widths of resonance levels in 65 Cu, 100 Mo, 118 Sn, 126 Te, 130 Te, 186 W and 209 Bi, were measured. The spins of the resonance levels were obtained by angular distribution measurements, and the parities by polarization measurements. The radiative widths were determined using nuclear self-absorption, temperature variation and absolute scattering cross section measurements. The total radiative widths were found to be of the same magnitude as those of neutron resonances, after applying a correction allowing for different excitation energies. Some E2 M1 mixing ratios of high energy transitions were obtained; the E2 widths were found to be of the same magnitude as those obtained in (n, γ) experiments.

Identification of fungal phytopathogens using Fourier transform infrared-attenuated total reflection spectroscopy and advanced statistical methods

The early diagnosis of phytopathogens is of a great importance; it could save large economical losses due to crops damaged by fungal diseases, and prevent unnecessary soil fumigation or the use of fungicides and bactericides and thus prevent considerable environmental pollution. In this study, 18 isolates of three different fungi genera were investigated; six isolates of Colletotrichum coccodes, six isolates of Verticillium dahliae and six isolates of Fusarium oxysporum. Our main goal was to differentiate these fungi samples on the level of isolates, based on their infrared absorption spectra obtained using the Fourier transform infrared-attenuated total reflection (FTIR-ATR) sampling technique. Advanced statistical and mathematical methods: principal component analysis (PCA), linear discriminant analysis (LDA), and k-means were applied to the spectra after manipulation. Our results showed significant spectral differences between the various fungi genera examined. The use of k-means enabled classification between the genera with a 94.5% accuracy, whereas the use of PCA [3 principal components (PCs)] and LDA has achieved a 99.7% success rate. However, on the level of isolates, the best differentiation results were obtained using PCA (9 PCs) and LDA for the lower wavenumber region (800-1775  cm(-1)), with identification success rates of 87%, 85.5%, and 94.5% for Colletotrichum, Fusarium, and Verticillium strains, respectively.

Study of the temperature effect of resonantly scattered capture γ-rays

Abstract The temperature effect of resonantly scattered capture γ-rays was studied critically in the temperature range 4.2°K–520°K in 208 Pb and in the range 4.2°K–670°K in 62 Ni. The γ-source was produced by thermal neutron capture in iron; the energy of the γ-line scattered by 208 Pb is7.279 MeV and by 62 Ni is 7.646 MeV. The observ intensity from Ni was found to be in good agreement with Lamb theory using a single Debye temperature, θ D = 420°K, throughout the whole temperature range. In the case of Pb, the agreement with Lamb theory using θ D = 104°K was not as good, and a deviation from theory was observed in the temperature range 30°K–70°K; this deviation is discussed.

Rayleigh and Delbruck scattering of 6.8–11.4 MeV photons at θ = 1.5°

Abstract An absolute measurement of the elastic scattering cross section of mono-energetic photons on Pb and U targets in the range 6.8–11.4 MeV at θ = 1.5° was carried out. Strong evidence for the real Delbruck amplitude and for Rayleigh scattering contributions from K-, L-, and higher-shell electrons is obtained.

Properties of nuclear levels excited by neutron capture γ-rays from cobalt

Abstract Neutron capture γ-rays from cobalt have been used to photoexcite nuclear levels in the 5–8 MeV region. The decay properties of the 7491 keV level in 55 Mn and the 6877 keV level in 142 Nd were studied in detail. Total and partial radiative widths of nuclear levels in several isotopes were determined using nuclear self-absorption, temperature variation, and absolute scattering cross section measurements. The total radiative widths were found to be of the same magnitude as those of unbound levels populated in neutron resonances. The spins and parities of some resonance levels were determined by carrying out angular distribution and polarization measurements, respectively.

The use of electron scattering for studying atomic momentum distributions: The case of graphite and diamond

The momentum distributions of C atoms in polycrystalline diamond (produced by chemical vapor deposition) and in highly oriented pyrolitic graphite (HOPG) are studied by scattering of 40 keV electrons at 135°. By measuring the Doppler broadening of the energy of the elastically scattered electrons, we resolve a Compton profile of the motion of the C atoms. The aim of the present work is to resolve long-standing disagreements between the calculated kinetic energies of carbon atoms in HOPG and in diamond films and the measured ones, obtained both by neutron Compton scattering (NCS) and by nuclear resonance photon scattering (NRPS). The anisotropy of the momentum distribution in HOPG was measured by rotating the HOPG sample relative to the electron beam. The obtained kinetic energies for the motion component along, and perpendicular to, the graphite planes were somewhat higher than those obtained from the most recent NCS data of HOPG. Monte Carlo simulations indicate that multiple scattering adds about 2% to the obtained kinetic energies. The presence of different isotopes in carbon affects the measurement at a 1% level. After correcting for these contributions, the kinetic energies are 3%-6% larger than the most recent NCS results for HOPG, but 15%-25% smaller than the NRPS results. For diamond, the corrected direction-averaged kinetic energy is ≈ 6% larger than the calculated value. This compares favorably to the ≈25% discrepancy between theory and both the NCS and NRPS results for diamond.

On the proton kinetic energy in H2O and in nanotube water

We calculated the kinetic energies of the H-atom in ice Ih between 5 and 269 K and in water in the range 293-673 K. To do so we used the literature optical vibration frequencies of ice and water of the different phases assuming the harmonic approximation and decoupling between the degrees of freedom of translation, rotation (libration), and internal vibrations. Apart for ice at 269 K, good agreement was obtained with published experimental values for both cases. Similar agreement with experiment was found for the case of water confined in 14 A diameter carbon nanotubes at 268 K. However, serious deviations from measured values were found in nanotube water in the range 5-230 K. Possible reasons for those deviations are discussed.

Anomalous kinetic energies of adsorbed 4He on active carbon fibre (ACF)

Direct measurements of the kinetic energies of He atoms adsorbed on active carbon fibre (ACF), at submonolayer coverage, are reported. The electronvolt spectrometer (eVs) of the ISIS neutron source, that utilizes the neutron Compton scattering technique, was employed. The specific adsorption area of the ACF was 3000 m2 g-1. The momentum distribution of adsorbed helium was measured at 4.6 K and 10.2 K and the average kinetic energy Ks was found: 54.3±3.0 K. This value is 30% higher than that estimated by assuming slit-shaped pores of dimensions ~0.7 nm together with a nearly monolayer coverage on a graphitic type adsorber.