X-ray fluorescence in some rare earth and high Z elements excited by 661.6 keV γ-rays

The K-shell X-ray fluorescence cross sections are determined experimentally for 10 elements such as Pb, Hg, Ir, W, Lu, Tm, Dy, Tb, Gd and Nd at excitation energy of 661.6 keV associated with γ-rays of ¹³⁷Cs radioisotope. The technique employed involves the measurement of total intensity of fluorescent K X-rays that follow the photoeffect absorption of a known flux of γ-rays using a well type Nal(Tl) detector. The obtained results are compared with the available theoretical values and other measured values.     

New indoline spiropyrans with highly stable merocyanine forms

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Spectroscopic study of the purple sulfur bacteria <Emphasis Type="Italic">Chromatium</Emphasis> sp. cultured in an aqueous medium

A spectroscopic study of the photosynthetic purple sulfur bacteria of the Chromatium genus is performed at various growth stages and under different culture conditions. Absorption and luminescence spectra of the bacterial cells are found to be useful in estimating their populations within certain concentration ranges. The relative proportion between the porphyrin and blue-band luminescence intensities can be used as an indicator of the physiological state of the culture.     

Photo- and Ionochromism of Benzoxazolyl-Substituted Spirobenzopyrans

8-Benzoxazolyl-6-formyl-substituted spirobenzopyrans with different acceptor groups in the 5'- position of the indoline moiety have been synthesized. Novel spiropyrans exhibit photochromic properties in an acetone solution at room temperature and form intensely colored complexes with heavy metal cations.     

New Photochromic Salt Spiropyran with Benzyl Substituent

A new salt spiropyran of indoline series containing benzyl substituent in the 8'-position of the [2H]-chromene moiety of the molecule has been synthesized and studied. The structure of the obtained compound has been confirmed by methods ¹H NMR and IR spectroscopy. The study of spectral characteristics and photochromic behavior of the target compound has shown that growing of its single crystal resulted in destruction on account of hydrolysis in acetonitrile. The ¹H NMR spectra of the initial salt spiropyran and product of hydrolysis have been compared.     

Mass spectrometry in the investigation of β-lysine-containing peptides

Mass spectrometry can be used for amino acid sequence determination in β-lysine-containing peptides and for the identification of α- and β-lysine residues in peptides, as well as for amide bond type determination in β-lysine peptides. The peptide bond in streptothricin D is shown to be formed through the participation of an ε-amino group of the L-β-lysine residue.     

Photodynamic chromogenic system based on photo- and ionochromic 8-(1,3-benzoxazol-2-yl)-substituted spirobenzopyran

8-(1,3-Benzoxazol-2-yl)-substituted spirobenzopyran is a new chromogenic system in which complexation with metal ions accompanied by a change in color can be controlled by photoirradiation. According to X-ray crystallography, the merocyanine ligand in the zinc complex has the TTT conformation.     

Spiropyrans and spirooxazines 12. Synthesis and complexation of a rhodamine-substituted spiro[benzopyran-indoline]

A new spirobenzopyranindoline containing a rhodamine fragment bonded by an azomethine spacer with the benzopyran fragment was synthesized based on 6-formyl-7-hydroxy-substituted spiropyran; the new compound exhibited complexation properties in solutions.     

New Photochromic Spiropyrans with <Emphasis Type="Italic">ortho</Emphasis>-Hydroxyaldimine Substituent

A series of new spiropyrans of indoline series with ortho-hydroxyaldimine substituent has been synthesized, their structure and photochromic properties have been studied. The structure of the obtained compounds was confirmed by the data of 1H NMR and IR spectroscopy and elemental analysis. Photochromic properties of the prepared compounds have been studied. The introduction of ortho-hydroxy group into aldimine fragment of molecule (in the 6 position of the 2H-chromene fragment) has increased the lifetime of merocyanine isomer by 40 times as compared with amino-substituted spiropyran.     

Pellet freezing of in vitro produced bovine embryos using dry ice

In vitro produced bovine embryos were frozen by pellet freezing or vitrification method. In the pellet freezing method, the embryos were cooled on the dry ice and then frozen as pellets. At warming, the pellets were immersed directly into 0.5 M sucrose. The survival rates of blastocysts frozen by the pellet freezing method were higher (P<0.01) in 40% ethylene glycol (EG) than those in the lower concentrations (20 and 30% EG). Higher survival rates of blastocysts frozen by the pellet freezing method were obtained but the development rates did not differ, as compared with those by the vitrification method. There were no significant differences between the pellet freezing and vitrification method in the frequencies of post-thaw survival of hatched blastocysts. These results demonstrate that the pellet freezing method using dry ice can be used successfully for the cryopreservation of blastocysts.