LUMINESCENCE OF CADMIUM SULFIDE QUANTUM DOTS IN FLUOROPHOSPHATE GLASSES

Cadmium sulfide quantum dots are perspective materials in optics, medicine, biology and optoelectronics. Fluorophosphate glasses, doped with cadmium sulfide quantum dots, were examined in the paper. Heat treatment led to the formation of quantum dots with diameters equal to 2.8 nm, 3.0 nm and 3.8 nm. In view of such changes in the quantum dots size the fundamental absorption edge shift and the luminescence band are being displaced to the long wavelengths. Luminescence lifetime has been found to be dependent on the registration wavelength in the range from 450 to 700 nm. Obtained fluorophosphate glasses with CdS quantum dots can find their application as fluorescent materials with intensive luminescence band and long excited-state natural lifetime

INTERACTION OF SILVER MOLECULAR CLUSTERS, INTRODUCED BY LOW-TEMPERATURE ION EXCHANGE METHOD, WITH NANOPARTICLES OF CdS IN FLUORINE PHOSPHATE GLASSES

Glasses with metallic and semi-conductive nano-particles appear to be perspective non-linear and luminescent materials of photonics. It was shown in theory that composite optical materials containing semi-conductive CdS-core with Ag shell (or vice versa) are optimal for enhancement of non-linear Kerr effect. Interaction of such an ensemble of particles leads to the forming of Ag island structures on the CdS particle, and formation of acanthite Ag2S on the two phases border (CdS-Ag) is minimal. In glasses synthesis of CdS quantum dots occurred due to thermal treatment close to glass transition temperature; introduction of silver was realized by low-temperature ion exchange (LIE). The main object of this work is investigation of Ag+ -LIE effect on the growth of CdS nano-particles. Two glasses were explored in this work: without CdS (glass 1) and with CdS (glass 2), processed by LIE at the temperature of 320°С for 10, 20 and 30 minutes and subsequent heat treatment at temperatures of 410°С and 420°С. In case of glass 1, intensive luminescence appears as a result of LIE, and subsequent heat treatment results in surface resonance at λ=410 nm. In case of glass 2, absorbance spectra change appears that is specific for formation of acanthite and weak luminescence shifting to long-wavelength region (from 550 to 700 nm) as a result of applying LIE and heat treatment. It indicates the growth of CdS quantum dots. Experiment has shown that quantum efficiency increases to 70% for glass 2 containing CdS quantum dots without LIE, while glass that contains silver shows steep decrease of quantum efficiency to 0%. That decrease is caused by formation of acanthite Ag2S on the surface of CdS quantum dot

Self-force of a point charge in the space-time of a massive wormhole

We consider the self-potential and the self-force for an electrically charged particle at rest in the massive wormhole space-time. We develop general approach for the renormalization of electromagnetic field of such particle in the static space-times and apply it to the space-time of the wormhole with parameter of the mass, $m$. The self-force is found in manifest form; it is an attractive force. We discus the peculiarities due to massive parameter of the wormhole.Comment: 10 pages, 1 figure text correcte

Knockdown of hexokinase 2 results in a decreased expression level of the glycolytic enzymes PFKP, BPGM, and GPI in RKO cell line

Colorectal cancer (CRC) is one of the most common malignant neoplasms in the world, and is characterized by a high mortality rate. The study of the key aspects of colorectal cancer formation and progression is necessary to develop new approaches to its therapy, as well as to search for new diagnostic, prognostic and predictive biomarkers of CRC. In many types of tumors, one of the key changes in metabolism is the  activation of glycolysis, which is associated with alterations in the expression of the main glycolytic enzymes and regulatory molecules. There is often an increase in hexokinase 2 (HK2) exogenous expression in tumor cells, which makes it a promising target for anticancer therapy. Quantitative expression analysis of 15 genes (GAPDH, ADPGK, ALDOA, ENO3, PFKL, PGK1, PGAM1, PKM2, ENO1, PDK1, PDK3, PFKP, ENO2, GPI, and BPGM), encoding the key glycolysis enzymes, as well as HIF1A gene was carried out in a modified RKO cell line, which constantly expresses the short hairpin RNA (shRNA) for the inhibition of hexokinase 2. A significant decrease in the expression of PFKP, BPGM, and GPI genes both at the mRNA (5­, 86­, and 93­fold, respectively) and protein (2.5­, 3.5­, and 19­fold, respectively) levels was revealed. Probably, the downregulation of GPI and PFKP is associated with a decrease in the amount of their substrates, glucose­6­phosphate and fructose6­phosphate, under the inhibition of hexokinase 2. Nevertheless, the cause of a decreased mRNA level of these three enzymes, while the expression level of other glycolytic participants is constant, requires further investigation

Aspergillus Myosin-V Supports Polarized Growth in the Absence of Microtubule-Based Transport

In the filamentous fungus Aspergillus nidulans, both microtubules and actin filaments are important for polarized growth at the hyphal tip. Less clear is how different microtubule-based and actin-based motors work together to support this growth. Here we examined the role of myosin-V (MYOV) in hyphal growth. MYOV-depleted cells form elongated hyphae, but the rate of hyphal elongation is significantly reduced. In addition, although wild type cells without microtubules still undergo polarized growth, microtubule disassembly abolishes polarized growth in MYOV-depleted cells. Thus, MYOV is essential for polarized growth in the absence of microtubules. Moreover, while a triple kinesin null mutant lacking kinesin-1 (KINA) and two kinesin-3s (UNCA and UNCB) undergoes hyphal elongation and forms a colony, depleting MYOV in this triple mutant results in lethality due to a severe defect in polarized growth. These results argue that MYOV, through its ability to transport secretory cargo, can support a significant amount of polarized hyphal tip growth in the absence of any microtubule-based transport. Finally, our genetic analyses also indicate that KINA (kinesin-1) rather than UNCA (kinesin-3) is the major kinesin motor that supports polarized growth in the absence of MYOV

STUDY OF STRONG CONFINEMENT OF CADMIUM SELENIDE QUANTUM DOTS IN FLUORINE-PHOSPHATE GLASSES

Fluorine-phosphate glasses doped with CdSe quantum dots were studied. As a result of glasses secondary heat-treatment, quantum dots were synthesized with sizes equal to 1.2-4.5 nm. Strong confinement was studied in two energy transitions (excited states of quantum dots) on photoluminescence excitation spectra. Experimental dependencies for the first and second energy transition on the nanoparticles size enable to conclude that no interaction occurs with fluorine-phosphate glass matrix and quantum dots