Efficiency estimates and practical aspects of an optical Kerr gate for time-resolved luminescence spectroscopy.

We report experience of assembling an optical Kerr gate setup at the Femtosecond Laser Center for collective use at the Institute of Physics of the National Academy of Sciences of Ukraine. This offers an inexpensive solution to the problem of time-resolved luminescence spectroscopy. Practical aspects of its design and alignment are discussed and its main characteristics are evaluated. Theoretical analysis and numerical estimates are performed to evaluate the efficiency and the response time of an optical Kerr gate setup for fluorescence spectroscopy with subpicosecond time resolution. The theoretically calculated efficiency is compared with the experimentally measured one of ~12% for Crown 5 glass and ~2% for fused silica. Other characteristics of the Kerr gate are analyzed and ways to improve them are discussed. A method of compensation for the refractive index dispersion in a Kerr gate medium is suggested. Examples of the application of the optical Kerr gate setup for measurements of the time-resolved luminescence of Astra Phloxine and Coumarin 30 dyes and both linear and nonlinear chirp parameters of a supercontinuum are presented.

Self-assembly of nanohills in Si1-xGe(x)/Si hetero-epitaxial structure due to Ge redistribution induced by laser radiation.

The study is focused on formation and optical properties of nanostructures induced by laser radiation on the surface of Si1-xGe(x)/Si hetero-structures. Formation of self-assembling nanohills induced by irradiation of nanosecond Nd:YAG laser pulses on the Si0.7Ge0.3/Si hetero-epitaxial structures is reported. The atomic force microscope study of the irradiated surface morphology has shown a start of nanohills formation after laser irradiation of the intensity I = 7.0 MW/cm2. The huge "blue shift" of photoluminescence spectra with maximum intensity in region of 700-800 nm (1.76-1.54 eV) is explained by the quantum confinement effect in the nanohills. The maximum of this photoluminescence band slightly shifts to shorter wavelengths with the increase of the intensity of laser pulses used for sample treatment. Appearance of the 300 cm(-1) Ge-Ge vibration band in Raman scattering spectra for sample irradiated with I = 20.0 MW/cm2 is explained by Ge phase formation. Formation of the Ge-rich phase is explained by localization of Ge atoms drifting toward the irradiated surface under the thermal gradient due to strong absorption of laser radiation. Ellipsometric data confirm appearance of Ge-rich phase precipitates amounting to 7.1%, 6.4% of the total Ge content induced by laser radiation of intensities I1 = 20.0 MW/cm2, I2 = 7.0 MW/cm2 respectively.

Ultra-stable nanoparticles in A(II)B(VI), (A(II) = Cd, Zn; BVI, = S, Se, Te) compounds.

Laser ablation on binary A(II)B(VI) compounds exhibits in time-of-flight mass spectra abundant peaks at stoichiometric (A(II)B(VI)),n with n = 13, 19, 33 and 34 measured on bulk powders of CdSe, CdS, CdTe, ZnS and ZnSe. Investigation on solution grown nanometer size particles of CdSe shown an existence of ultra-stable stoichiometric clusters (CdSe)13, (CdSe)19, (CdSe)33, (CdSe)34 and (CdSe)48. This set of n has not been predicted as particularly stable particles in previous bulk fragment models based on either zinc-blende or wurtzite, and a different type of structures is required to explain our experimental results. Present investigation shows that nanoparticles formed in vacuum as magic numbers above are found in solution as preferentially grown species in CdSe, and possibly in other A(II)B(VI). It is suggested that the high stability of the observed magic clusters originates from their specific structure as endohedral binary fullerenes, supposedly. These molecular-like particles composed of few tens of atoms lie between atom and solid, and exhibit novel materials functions not realizable in the bulk.

Fullerene C60-silver nanoparticles hybrid structures: optical and photoelectric characterization.

A detailed optical and photoelectric characterization of pristine fullerene C60 films deposited onto n-silicon substrates (C60/Si), C60 films crosslinked by means of the solvent-free chemical functionalization with 1,8-diaminooctane (C60-DA/Si), and the pristine and crosslinked films decorated with silver nanoparticles (C60-Ag/Si and C60-DA-Ag/Si), was carried out. The reflectance spectra obtained allowed to calculate the absorption coefficient (alpha = 4pik/lamda) spectral dependencies and the spectra of light transmittance in layered barrier structures metal(Au)/fullerene/Si. Photoelectric properties of the films were investigated as well. The experimentally measured values of band gap were in a good agreement with mobility gap values (2.3 +/- 0.1 eV). The decoration of fullerene films (both pristine and chemically crosslinked) with silver nanoparticles did not change the photocurrent spectra as compared to those for undecorated fullerene films, but lowered the values of internal quantum efficiency Qint. The photocurrent generated in fullerene/Si heterostructure, showed a maximum value at lamda to appromimately 450 nm (Qint max approximately = 0.25 for decorated and undecorated C60-DA/Si films), and it was higher for the samples based on pristine C60 films, in accordance with their higher absorption coefficient. Diminishing of Qint for C60-DA/Si and C60-DA-Ag/Si films was observed for the spectral range of photocurrent generated in Si layer. The analysis of dark current-voltage characteristics showed that the barrier properties differ insignificantly, though a certain increase of series resistance was observed for the C60-DA/Si samples.

[Comparative analysis of antimicrobial action of polyhexametylenguanide hydrochloride (Biopag) and chlorhexidine bigluconate upon potential infectious agent of suppurative-inflammatory diseases of maxillo-facial region and neck].

Sensitivity of microflora representatives isolated from inflammatory foci from 40 patients with suppurative-inflammatory diseases of maxillo-facial region and neck to different concentrations of antiseptic preparations of polyhexametylenguanide hydrochloride (Biopag) and chlorhexidine bigluconate was tested. It was determined that 0.05-0.1% solutions of these antiseptics were optimal for these diseases treatment. Biopag had more pronounced fungicidal action, less toxic and more prolonged antimicrobial action and better organoleptic properties when compared with chlorhexidine bigluconate.

[Medicolegal analysis of ARD mass cases occurred in servicemen].

The article presents the analysis of causes and outcomes of ARD and pneumonia incidence among the servicemen in one of the military units during the period 2002-2003. 95 forensic medical examinations were analyzed. The terms of disease occurrence, complications, unfavorable outcomes are presented. The defects in medical care rendering are shown. The recommendations on prophylaxis of such cases are shown.

Optical spectra and structure of CdP4 nanoclusters fabricated by incorporation into zeolite and laser ablation.

CdP(4) nanoclusters were fabricated by incorporation into the pores of zeolite Na-X and by deposition of the clusters onto a quartz substrate using the laser ablation-evaporation technique. Absorption and photoluminescence (PL) spectra of CdP(4) nanoclusters in zeolite were measured at temperatures 4.2, 77, and 293 K. Both absorption and PL spectra consist of two blue-shifted bands. We performed DFT calculations to determine the most stable clusters configuration in the size region up to the size of the zeolite Na-X supercage. The bands observed in absorption and PL spectra were attributed to the emission of (CdP(4))(3) and (CdP(4))(4) clusters with binding energies of 3.78 and 4.37 eV per atom, respectively. The Raman spectrum of CdP(4) clusters in zeolite proved the fact of creation of (CdP(4))(3) and (CdP(4))(4) clusters in zeolite pores. The PL spectrum of CdP(4) clusters produced by laser ablation consists of a single band that was attributed to the emission of the (CdP(4))(4) cluster.

[Pulmonary berylliosis]. / Berillioz legkikh.

A case of a chronic lung berylliosis in a 20-year-old woman with a 20-weeks pregnancy is described. The diagnosis is established on the basis of morphological features: fibrosing alveolitis with numerous lympho-histiocytic granulomas containing conchoidal bodies and the lung tissue chemical analysis showing the presence of beryllium (2.71 X 10(-6) g/organ). Morphology of the lungs is described in detail.

[Clinico-morphologic analysis of primary and metastatic tumors of the heart]. / Kliniko-morfologicheskii analiz pervichnykh i metastaticheskikh opukholei serdtsa.

The analysis of 7358 autopsies performed in 1966-1986 showed that cardiac tumors were detected in 94 cases (1.27%) and accounted for 4.9% of cancer and 5.48% of cardiac disease cases. Detailed characteristics are provided for 9 primary tumors, of these 3 were assessed clinically and morphologically, (left ventricular elastofibroma, left ventricular pleomorphic rhabdomyosarcoma, left atrial embryonal rhabdomyosarcoma). Primary metastases of pulmonary localization were recorded in 47.9% of cases. Metastatic involvement of the heart presented in 85 cases (1.15% of autopsies, 4.43% of cancer cases, 5% of cardiac affections, 90.42% of cardiac tumors). Cardiac compartments were evaluated for the frequency of tumor emergence.

[Dissecting aneurysm of the aorta: histochemical study using a set of lectins with different carbohydrate specificity]. / Rasslaivaiushchaia anevrizma aorty: gistokhimicheskoe issledovanie s primeneniem nabora lektinov razlichnoi uglevodnoi spetsifichnosti.

By means of lectin-peroxidase technique histotopography of receptor sites for Ricinus communis agglutinin (RCA), peanut agglutinin (PA), soybean agglutinin (SA), Sophora japonica lectin (SJL), wheat germ agglutinin (WGA), Laburnum anagyroides lectin (LAL), Lotus tetragonolobus lectin (LTL) and concanavalin A (con A) in normal aortic tissue sections as well as in dissecting aortic aneurysms (Gsell-Erdheim syndrome) has been investigated. It was demonstrated that fucose-specific LAL and LTL possess high selectivity of binding to aortic endotheliocytes, SA to neurocytes of autonomic nervous nodes. Gsell-Erdheim syndrome is accompanied by appearance of SA-binding sites around smooth myocytes with formation of specific SA-positive multivesicular shapes in aortic media. Possible role of the observed phenomena in pathogenesis of dissecting aortic aneurysm is discussed.

[Lectin receptors in transitional cell tumors of the bladder]. / Retseptory nekotorykh lektinov v perekhodno-kletochnykh opukholiakh mochevogo puzyria.

Binding sites for lectins of peanuts, soya-beans and concanavalin A were identified in the tissues of normal human urinary bladder and its transitional cell tumors (31 patients) using the lectin-peroxidase technique. No binding sites for any of the lectins were found in normal urothelium. Receptors for peanut and soya-bean lectins were observed on the plasma membranes of 20% of tumor cells in transitional cell papillomas. A diffuse distribution of those lectins in tumor cell cytoplasm was interpreted as a tendency to malignant transformation of tumor. There were no concanavalin A receptors in tumor cells.

[Lectin receptors in the breast and its tumors]. / Retseptory lektinov v molochnoi zheleze i ee opukholiakh.

Distribution of lectin receptors of peanut, soy-bean, wheat ovary and concanavalin A was studied in normal and tumor human breast tissue. It is established, that in dysplasia and benign neoplasms there is a shift of lectin receptors from the apical or basal pole of acinar epithelium and ducts to the whole plasmolemma surface. There appears a mild affinity of the cytoplasm to the lectins. In carcinoma homogeneous staining of tumour cell cytoplasm and plasmolemma increase. The number of lectin receptors in the cells from low differentiated tumours decreases, a major part of the cells losing the ability of binding to lectins. Malignancy is associated with an increase in mosaic staining. The earliest signs of malignancy can be revealed with the peanut lectin.

[Intratumoral proliferation of the blood vessels]. / Vnutriopukholevaia proliferatsiia sosudov.

The growth of vessels in experimental neoplasm occurs within 2-7 days after implantation. Newly formed vessels penetrate into the tumor only from the tissues of the tumor-carrying host. Vessels are formed in the tumor by budding. Proliferation of tumor cells begins only after the contact between them and the developing vascular network has been established. Myofibroblasts play an important role in the development of vessels. The intensity of new vessel formation is more than twice as high as in the wound process. The number of capillaries in developed tumors varies with an average of 30,000 in 1 mm2. Blood supply even within the same tumor is variable both in the form and location of the vessels. With increasing tumor volume intercapillary distances, diameter and length of the capillaries increase while the vascular bed volume, the general and local blood flow decrease. Reparation of the vascular bed in tumors occurs both due to preexisting vessels and by additional formation of new vessels. The muscular layer and innervation are lacking in the newly formed vessels. In the process of growth, compensatory-adaptative reactions directed to improvement of hemodynamics constantly develop in tumor tissues.