V. P. Zlomanov

Fluorescent immunolabeling of cancer cells by quantum dots and antibody scFv fragment

Semiconductor quantum dots (QDs) coupled with cancer-specific targeting ligands are new promising agents for fluorescent visualization of cancer cells. Human epidermal growth factor receptor 2/neu (HER2/neu), overexpressed on the surface of many cancer cells, is an important target for cancer diagnostics. Antibody scFv fragments as a targeting agent for direct delivery of fluorophores offer significant advantages over full-size antibodies due to their small size, lower cross-reactivity, and immunogenicity. We have used quantum dots linked to anti-HER2/neu 4D5 scFv antibody to label HER2/neu-overexpressing live cells. Labeling of target cells was shown to have high brightness, photostability, and specificity. The results indicate that construction based on quantum dots and scFv antibody can be successfully used for cancer cell visualization.

Nonstoichiometry and P–T–x diagrams of binary systems

Abstract A P–T–x three-dimensional space diagram forms the complete representation between pressure (P), temperature (T) and composition (x) of coexisting phases—solid (S), liquid (L) and vapor (V). It gives the number of nonstoichiometric compounds that may be formed by the components and the stability limits of phases which are in equilibrium. Definitions of stoichiometry and nonstoichiometry are given. Some features of P–T–x diagrams with nonstoichiometric compounds are considered: maximum (Tmmax) and congruent (Tmc) melting points, difference between the compositions of solid (xS), liquid (xL) and vapor (xV): xL≠xS≠xV at maximum melting point T=Tmmax, the width and position of the homogeneity range, and the nonstoichiometry caused by defects are also discussed. A new technique for the investigation of P–T–x diagrams is presented.

Phase diagram and thermodynamic properties of phases in the In-Te system

The In-Te phase diagram was refined in the composition range 0 to 71.77 at.% Te; the phases In4Te3, InTe, In2Te3, and In2Te5 were found to exist. Vaporization of In2Te3 and InTe was studied by the mass spectrometric method and the p Te 2 -T diagram was constructed. The standard molar enthalpies of formation of mentioned compounds were determined by direct synthesis calorimetry. The heat capacity of the solid In2Te3 was measured in a vacuum adiabatic calorimeter at 5 to 310 K, and the H o(T)-H o(0), S T , and G o(T)-H o(0) functions were calculated.

P-T-X phase diagram of the Pb-Se system and vapor phase growth mechanism of lead selenide single crystals

Abstract The mechanism and conditions for growth of PbSe crystals from the vapor phase have been determined and related to the P-T-X phase diagram. Observations of the growth process, morphological features of the growth surfaces, and the composition of as-grown crystals indicate that the investigated conditions growth seems to proceed via the vapor-liquid-solid mechanism. The real temperature difference between the charge and growth zone is 15–20°.

Features of Vanadium Impurity States in Lead Telluride

Temperature dependences of resistivity, magnetic susceptibility, and charge-carrier concentration and mobility in single-crystalline PbTe:V samples with a varied impurity content are investigated. It is shown that vanadium forms a donor level located ∼20 meV below the conduction-band bottom. The electron mobility is as high as 105 cm2 V−1 s−1 in the samples with NV ≤ 0.21 at % and proves to be more than an order of magnitude higher in the samples with the highest vanadium content NV = 0.26 at %. In the same samples, the real part of the conductivity is characterized by a pronounced frequency dependence. An increase in vanadium concentration is accompanied by a decrease in the effective magnetic moment of impurity atoms. The features of electron transport in PbTe:V may be caused by a variable vanadium valence and by the effect of interimpurity correlations.

PbTe-VTe2 phase diagram and properties of (PbTe)1 − x(VTe2)x solid solutions

The T-x phase diagram along the PbTe-VTe2 join of the Pb-V-Te system has been studied. Vanadium-doped lead telluride crystals have been grown, and the longitudinal vanadium and carrier profiles in the crystals have been investigated. The temperature dependences of resistivity for the crystals lend support to the conclusion drawn earlier that PbTe〈V〉 is in a semi-insulating state at low temperatures. The crystals offer a high 20-K electron mobility, on the order of 105 cm2/(V s), which attests to high electrical homogeneity of the material and stabilization of the Fermi level.

Synthesis and properties of vanadium-doped lead telluride

We have studied a portion of the ternary system Pb-V-Te. Pseudobinary joins have been identified, the vanadium solubility along the V3Te4-PbTe join has been determined, and the lattice parameter of the solid solution has been measured as a function of vanadium content at 800 and 870°C. Six PbTe〈V〉 crystals have been grown by the Bridgman method, and their microstructure and transport properties have been investigated. The results indicate that vanadium in PbTe is not a simple donor: its effect depends on those growth conditions that determine the degree of compensation of the donor effect of vanadium and native defects. PbTe〈V〉 samples have been found to pass into a high-resistivity state on cooling and to be photosensitive. The depth of the vanadium donor level in the band gap of lead telluride has been evaluated.

High-temperature hall effect measurements in indium-doped cadmium sulfide in sulfur vapor

High-temperature Hall effect measurements on indium-doped cadmium sulfide in cadmium and sulfur vapor, combined with the results of similar measurements on undoped CdS lead to the parameters of the equilibrium constant of Schottky disorder K″=410exp(−4.09eV/kT)site fr2 vacancy formation, KCdV=3.56× 109exp(−2.34eV/kT)site fr, and pairing of V″Cd with In·Cd Kp=6.7(×/:)25exp(0.47±0.3eV/kT)site fr

Chemical transport reactions as a new variant of the phase composition control

It is shown that the composition of low-volatility two-component compounds in the Ga-Se system can be controlled using chemical transport reactions (CTR). For long-term heat treatment of a low-volatility phase in the presence of a transport agent, the annealed phase composition was found to be determined only by the temperature conditions and the chemical nature of the sample. In the case of a two-temperature anneal of gallium selenides with added iodine, the sample stability domains are presented as a function of the cold and hot zones temperatures. The role of the transport agent is discussed. The possibility of applying this technique to other binary systems with low-volatility phases is also considered.

Manometric method for the study of P-T-X diagrams

A new null-manometric method has been elaborated and applied for investigations fo the systems with the low-volatile compounds. The essence of this method is in obtaining the phase diagram for low-volatile binary compounds using the temperature dependence of equilibrium nonsaturated vapor pressure, formed by a third (auxiliary) component, which is put in contact with the investigated system. The aim of applying the third component assumes its reversible chemical interaction with one of the components of a weakly volatile compound. This compound component is converted into vapor (in the form of a compound with the auxiliary component) and the composition of a condensed part of the system is changed. Controlling equilibrium with temperature adjustment makes possible control of the disappearance of some of the condensed phases and formation of the others. Changes in equilibrium when employing this process are clearly observed in the temperature dependence of the vapor pressure. From the data, it is possible to trace the correlation between the total vapor pressure and the composition of binary condensed phases, as well as the correlation between the total and partial pressures. The overall results allow determination of the phase diagram.