Laws of nanosize molybdenum (VI) oxide layers optical properties change as a result of heat treatment

The spectrophotometric method determines two absorption and reflection spectral areas of nanosize MoO3 layers - short-wave ?330 nanometers. It is stated by spectrophotometric, gravimetric and microscopic methods that in atmospheric conditions MoO3 layers transformation degree (d=10...130 nm) grows at time (1...140 minutes) and heat treatment temperatures (Т=373...600 К) (at constant layer thickness) increasing as well as at reduction of layers thickness. The reduction of absorption maxima at ?=350 nm and increase at ?=870 nanometers at heat treatment of MoO3 layers is revealed. The colour centers formation model is offered. It includes the center formation - anionic vacancy with one seized electron ([(Vа) ++ е]) during preparation of MoO3 layer, thermal electron transition from a valent zone on a level of the center, the second electron capture by the center ([(е Vа) ++ е])

Photolysis of lead azide in contact with copper oxide (I)

It is stated that alongside with decrease of photolysis velocity and photocurrent in the area of intrinsic absorption of lead azide the addition of Cu2O extends the range of spectral sensitivity, but preliminary processing of the system by light (?=365 nm) increases photolysis velocity. As a result of analysis of volt-ampere characteristic measurements, contact potential difference, contact photo-emf the model of system PbN6(Ам)-Cu2O photolysis including stages of generation, recombination, redistribution of nonequilibrium carrier in a contact field, formation of microheterogeneous PbN6(Ам)-Pb systems (photolytic product), as well as formation of photolytic final products is proposed

Influence of the method of synthesis on lead azide photolysis

Lead azide irrespective of method of synthesis shows the general kinetic regularities. On kinetic curves of photolysis speed PbN6(Аб) characteristic sites have been defined: initial, stationary, increased and saturation. Time of the sites realization as well as the photolysis speed depends on the way of PbN6(Аб) synthesis. Preliminary light processing of PbN6(Аб) at ?=380 nm and I=2·1015 quantum·sm-2·s-1 in vacuum (Р=1·10-5 Pа) along with increase in photolysis speed and photocurrent in own area of absorption results in appearence of new long-wave area of spectral sensitivity. Quantum outputs and constants of photolysis speed of PbN6(Аб) are determined. It is experimentally stated that the values of photocurrent observed in the field of long-wave threshold of photosensivity coincide with the designed values of photoemission current on the border of PbN6(Аб)-Pb. This fact as well as the measurements results of volt-ampere characteristics, contact photoelectrical moving force, contact potential difference reveals the formation of microheterogeneous PbN6(Аб)-Pb systems (a photolysis product) at photolysis of lead. A limiting stage of PbN6(Аб) photolysis is anion vacancies diffusion to neutral center of Pbn0

Silver azide photolysis

The preliminary silver azide light irradiation (?=365 nm, I>1·1015 quanta·cm-2·с-1) in vacuum (Р=1·10-5 Pа) alongside with increase in photolisys speed and a photocurrent results in occurrence new long-wave (up to ?=1280 nm) area of spectral sensitivity. Constants of silver azide photolysis speed are determined. As a result of measurements of a contact potential difference, volt - ampere of characteristics, a contact photoelectrical moving force, a photocurrent it is established, that at silver azide photolisys microheterogeneous systems AgN3 (А1) - Аg (a product photolisys) are formed. It is shown, that a limiting stage of silver azide photolisys is diffusion of the mobile ion of silver to neutral center (ТnAgm)0

Thermal transformations of aluminium-aluminium oxide systems in nanosize layers

Aluminium film of more than 2 nm thick indicates, but less than 2 nm do not indicate characteristic absorption and reflection bands for aluminium in range ?=190...1100 nm. By spectrophotometric, gravimetric and microscopic methods it is stated that thickness, mass and absorption, reflection spectrum of aluminium films (d=2...200 nm) undergo considerable transformations as a result of heat treatment in an interval of temperatures 373...600 K during 1...140 min in atmospheric conditions. Kinetic curve of transformation degrees, change of thickness and weights of samples are shown to be satisfactorily described in the context of the logarithmic law. It is established that changes of absorption spectra, thickness and weights of aluminium films are connected with the formation of aluminium oxide on their surface

Characterization of Ku702–NLS as Bipartite Nuclear Localization Sequence for Non-Viral Gene Delivery

Several barriers have to be overcome in order to achieve gene expression in target cells, e.g. cellular uptake, endosomal release and translocation to the nucleus. Nuclear localization sequences (NLS) enhance gene delivery by increasing the uptake of plasmid DNA (pDNA) to the nucleus. So far, only monopartite NLS were analysed for non-viral gene delivery. In this study, we examined the characteristics of a novel bipartite NLS like construct, namely NLS Ku70. We synthesized a dimeric structure of a modified NLS from the Ku70 protein (Ku702-NLS), a nuclear transport active mutant of Ku702-NLS (s1Ku702-NLS) and a nuclear transport deficient mutant of Ku702-NLS (s2Ku702). We examined the transfection efficiency of binary Ku702-NLS/DNA and ternary Ku702-NLS/PEI/DNA gene vector complexes in vitro by using standard transfection protocols as well as the magnetofection method. The application of Ku702-NLS and s1Ku702-NLS increased gene transfer efficiency in vitro and in vivo. This study shows for the first time that the use of bipartite NLS compounds alone or in combination with cationic polymers is a promising strategy to enhance the efficiency of non-viral gene transfer

Amino acid requirements of the nucleocapsid protein of HIV-1 for increasing catalytic activity of a Ki-ras ribozyme in vitro

The nucleocapsid protein NCp7 of HIV-1 is a single-stranded nucleic acid binding protein with several functions such as specific recognition, dimerization and packaging of viral RNA, tRNA annealing to viral RNA and protection against nucleases. Since some of these functions involve annealing and double-stranded RNA-melting activity we applied the nucleocapsid protein to a hammerhead ribozyme specific for the activated Ki-ras mRNA in vitro, which carries at its mutated codon 12 a GUU site. A synthetic ribozyme containing 2'-O-allyl-modified nucleotides and alternatively in vitro transcribed ribozymes were used. At a one to one molar ratio of substrate to ribozyme almost no cleavage is observed at 37 degrees C. Presence of a synthetic nucleocapsid protein significantly increases the catalytic activity of the ribozyme. Kinetic analyses by means of single and multiple turnover reactions performed at various substrate to ribozyme ratios lead to only a slight stimulation of the rate constants for single turnover reactions. The rate constants in multiple turnover reactions, however, are stimulated up to 17-fold by the presence of the nucleocapsid protein. The activating region of the nucleocapsid protein was characterized by a number of mutants. The mutants demonstrate that activation requires both basic amino acid clusters as evidenced by point mutations. Deletion mutants indicate that the second zinc finger is totally dispensable and that replacement of the first zinc finger by a glycine-glycine spacer only slightly reduces the enhancing effect of the nucleocapsid protein on the ribozyme