Chitosan nanocomposites with CdSe/ZnS quantum dots and porphyrin.

Water-soluble nanocomposites based on CdSe/ZnS quantum dots (QDs) and hydrophobic tetraphenylporphyrin (TPP) molecules passivated by chitosan (CS) have been formed. Magnetic circular dichroism (MCD) spectra evidence TPP presence in both monomeric and agglomerated forms in the nanocomposites. The nanocomposites demonstrate more pronounced singlet oxygen generation compared to free TPP in CS at the same concentration due to the intracomplex Förster resonance energy transfer (FRET) with a 45% average efficiency.

Enantioselective cellular uptake of chiral semiconductor nanocrystals.

The influence of the chirality of semiconductor nanocrystals, CdSe/ZnS quantum dots (QDs) capped with L- and D-cysteine, on the efficiency of their uptake by living Ehrlich Ascite carcinoma cells is studied by spectral- and time-resolved fluorescence microspectroscopy. We report an evident enantioselective process where cellular uptake of the L-Cys QDs is almost twice as effective as that of the D-Cys QDs. This finding paves the way for the creation of novel approaches to control the biological properties and behavior of nanomaterials in living cells.

Chlorin e6-ZnSe/ZnS quantum dots based system as reagent for photodynamic therapy.

Stable water-soluble complexes of Cd-free ZnSe/ZnS quantum dots (QDs) and chlorin e6 complexes have been prepared. These complexes have shown approximately 50% intracomplex fluorescence resonance energy transfer from QDs to chlorin e6. The photodynamic therapy (PDT) test of the complexes against the Erlich acsite carcinoma cell culture demonstrated a two-fold enhancement of the cancer cell photodynamic destruction as compared to that of free chlorin e6 molecules. It was shown that the PDT effect was significantly increased due to two factors: the efficient QD-chlorin e6 photoexcitation energy transfer and the improvement of cellular uptake of the photosensitizer in the presence of ZnSe/ZnS QDs.

[Focal nodular liver hyperplasia].

It was evaluated the frequency of focal nodular liver hyperplasia and treatment resultsin 1425 patients for the last 17 years in 2 time period. The own experience and literature data were used. First this disease was considered as very rare liver tumor because of underdeveloped diagnostics. Tumor detection was the indication for laparotomy. In some patients removal of the tumor was not performed if intraoperativebiopsy has shown tumor benign. The indication for dynamic observation and surgical treatment were identified with increasing number of patients, diagnostics improvement, and analysis of immediate and long-term results. The operation provides persistentcure.

Reversible photoluminescence quenching of CdSe/ZnS quantum dots embedded in porous glass by ammonia vapor.

The photoluminescence response of semiconductor CdSe/ZnS quantum dots embedded in a borosilicate porous glass matrix to exposure to ammonia vapor is investigated. The formation of surface complexes on the quantum dots results in quenching of the photoluminescence and a shortening of the luminescence decay time. The process is reversible, desorption of ammonia molecules from the quantum dot surface causes the photoluminescence to recover. The sensitivity of the quantum dot luminescence intensity and decay time to the interaction time and the reversibility of the photoluminescence changes make the CdSe/ZnS quantum dots in porous glass system a candidate for use as an optical sensor of ammonia.

Track membranes with embedded semiconductor nanocrystals: structural and optical examinations.

We studied the optical properties of poly(ethylene terephthalate) ion track membranes of 1.5, 0.5 and 0.05 µm pores impregnated with luminescent semiconductor CdSe/ZnS nanocrystals of different diameters (2.5 and 5 nm). The nanocrystals were embedded from their colloidal solutions in toluene by the immersion of a membrane in a colloidal solution. Localization of quasi-isolated weakly interacting CdSe/ZnS nanocrystals in a loosened layer on the track pore wall surface along with the existence of empty pores was demonstrated. We observed also the spatial separation of nanocrystals of 2.5 and 5 nm in size along the 50 nm pores.

[Expanded D2 lymphodissection in combined treatment of gastric cancer: unification of treatment approaches].

The authors present an analysis of results of using D2 operations in combined treatment of gastric cancer. Such volumes of operations combined with preoperative irradiation are not followed by greater number of complications and lethality. The incidence of progressing in terms more than a year proved to be considerably lower in the group of patients with combined treatment with D2 lymphodissection than in the groups without lymphodissection and preoperative radiation therapy.

[Study of primary photoprocesses in photosystem II of Chlamydomonas mutant strains by hole-burning spectroscopy]. / Issledovanie pervichnykh fotoprotsessov v fotosisteme 2 mutantov khlamidomonady metodom spektroskopii vyzhiganiia provalov.

The method of hole-burning in absorption spectra at helium temperatures has been applied to the study of primary photoprocesses in photosystem II (PS2) of Chlamydomonas reinhardii mutant strains 420/7 and N-154. The former is enriched in PS2 reaction centers (the chlorophyll a/P680 ratio is about of 50--70) and the latter presumably lacks the pheophytin molecule which is the primary electron acceptor in PS2. For the strain 420/7 samples with ferricyanide addition two types of holes have been observed differing in their width and spectral region of burning. One type could be burned in the region of 678--682 nm (P680 is responsible for burning) and another one -- in the region of 682--688 nm (pheophytin is responsible). The excited states relaxation times evaluated from the hole widths are 3,8 +/- 0,8 ps for P680 and 9,8 +/- 1.5 ps for pheophytin. The new mechanism of PS2 operating has been proposed in which photoexcited phenophytin molecule functions as a primary electron donor. In the case of N-154 strain the only type of holes has been observed for which P680 is responsible. The excited state relaxation time of the latter evaluated from the hole width is 10 +/- 2 ps.

[Extraperitoneal approaches in surgery on the abdominal aorta and its branches]. / Vnebriushinnye dostupy v khirurgii briushnoi aorty i ee vetvei.

The use of extraperitoneal accesses was analyzed in 163 reconstructive operations on the abdominal aorta and its branches. A wide use of them is shown to be expedient. Seven types of extraperitoneal accesses are described with special reference to their advantages and shortcomings and indications for each of them. The work also discusses one of extraperitoneal accesses for lumbar sympathectomy (used in 312 patients). It is estimated positively.

[Spectroscopic study of "hole burning" of the initial photoprocesses in photosystem I of mutant strain Chlamydomonas reinhardii 516-3a enriched with P700 reaction centers]. / Issledovanie metodom spektroskopii "vyzhiganiia provalov" pervichnykh fotoprotsessov v fotosisteme 1 mutantnogo shtamma Chlamydomonas reinhardii 516-3a, obogashchennogo reaktsionnymi tsentrami P700.

The effect of "hole burning" in absorption spectrum upon monochromatic illumination at 4.2 degrees K has been investigated on the Chlamydomonas reinhardii mutant strain 516-3a which possesses the chlorophyll a/P700 ratio of about 25. This effect has been earlier discovered for the wild type strain of Chlorella. In the strain 516-3a two types of holes differing in width and in shape have been observed. For their assignment the maximal (saturated) holewidth has been studied as a function of the burning wavelength. It has been shown that for the holes of one type photooxidation of P700 is responsible. The other type of holes is caused by electrochromic transition shift of another component of the reaction centre with the absorption maximum at 693 nm. Using measured holewidths it has been estimated that the lifetime of P700 excited state is not less than 50 ps and that the excited state lifetime of the component responsible for the other type of holes is 8.6 ps. The latter, in assumption that it is limited by energy transfer between two components under consideration, gives a distance of 20 A between them. Possible reasons of disagreement between obtained P700* lifetime and considerably shorter times attributed earlier to the primary electron phototransfer in photosystem I on the basis of picosecond studies are discussed.

["Burning" of troughs in the low-temperature absorption spectra of a strain of Chlamydomonas reinhardii enriched by P700]. / Vyzhiganie provalov v nizkotemperaturnykh spektrakh pogloshcheniia shtamma Chlamydomonas reinhardii, imeiushchego obogashchenie po P700.

Spectral and photochemical parameters were described of the mutant strain of Chlamydomonas reinhardii 516--3a, in which the ratio chlorophyll a/P700 is about 20. Experiments were carried out with this strain for investigating earlier observed for Chlorella effect of burning out of deeps in absorption spectra at 4.2K resulting from irradiation with monochromatic light of the wavelength 698 nm. Arguments are presented in favour of the assumption that phototransformation of P700 is responsible for the formation of deeps. It has been found from the width of the deeps that the lifetime of the excited states of the centres responsible for the formation of deeps is between 16 ps and 65 ps.