Search

A special case disclosing the mechanism through which an inadequate result occurs in representing the semiconductor switches by means of piecewise-linear approximation is considered taking as an example the discrete model of a three-phase uncontrolled rectifier. It has been found in analyzing the voltages across the switches of the non-conducting three-phase bridge that with certain ratios of the load counter EMF and the amplitude of the line-to-line network EMF at any moment of time, the voltage across one of the non-conducting bridge switches is positive whereas the voltages across all other switches are negative. As a consequence, fluctuations of the switch state alterations occur that are not typical for the operation of a real circuit. Factors causing the inadequacy of piecewise-linear models to the physical ideas about the circuit operation are revealed, and the consequences arising due to this in the discrete models of rectifies are pointed out. Recommendations on the ways for eliminating the factors causing inadequate modeling are given.

Improvement the mechanisms and levels of adhesion forces of dental photocomposite filling (restorative) materials to hard tissues of teeth, improvement of filling materials and increasing their availability is an urgent problem for theoretical and practical dentistry. Aim of the study - experimental evaluation of the strength of adhesion to the hard tissues of non-vital teeth for adhesive systems in combination with modern dental photocomposite filling (restorative) materials. 80 tests of the adhesion strength of the dental photocomposite filling (restorative) material to the tooth hard tissues (shear strength) were carried out for 8 pairs of "photocomposite-adhesive system" using an automated tensometric system. The strength of adhesion of the filling material to the hard tissues of non-vital teeth (shear strength) has a wide range of differences. The average value was 18.74±4.48 (M=19.63) MPa, the average minimum value was 10.89±2.47 (M=9.95) MPa, and the maximum value was 33.18±16.35 (M=24.35) MPa, while individual pairs of materials and adhesive systems demonstrated an adhesion force from 8.56 to 66.00 MPa.

The importance of control for nosocomial and community-acquired infections is one of the priorities of practical surgery, and maxillofacial surgery is no exception in this matter. Aim of study - to determine the spectrum of antimicrobial activity of widespread antiseptics and antibacterial agents used for topical treatment of odontogenic phlegmons of the maxillofacial region. A bacteriological study of purulent wound exudate was carried out for 109 patients of the maxillofacial hospital department with a diagnosis of odontogenic phlegmons. Using the method of "draw-wells" the sensitivity of the isolated bacterial cultures to solutions of decamethoxin, dioxidine, formaldehyde, and sanguiritrin was determined. Using the dilution method microbicide concentrations of decamethoxin and miramistin were determined by influencing the clinical and museum strains of pathogenic bacteria. In purulent exudate the monocultures of staphylococci were determined - 79 (40.1%), and streptococci - 86 (43.65%), aerobic non-fermenting bacteria - 11 (5.60%) and enterobacteria - 21 (10,65%) were found much less often. Isolated from S. aureus and E. coli proved to be sensitive to solutions of decamethoxin, formaldehyde and sanguiritrin; isolated strains of P. aeruginosa - only to decamethoxin and formaldehyde. Microbicide concentrations of decamethoxin were 4-35 times lower than miramistin due to effect on clinical and museum strains of bacteria. Efficiency of decamethoxin was higher.

The problem of complex dental rehabilitation of a patient after partial or complete teeth loss is an urgent issue for dental practice. The most of patients coming to dentist with to make dentures on dental implants after tooth loss in lateral part of maxilla are often observed with atrophy of the alveolar bone resulting in maxillary sinus (sinus Haymori) enlargement. Creating an additional space for dental implant placement in the maxilla is possible by performing a sinus lift (subantral maxilla augmentation) - artificially thickening the lower and outer wall of the maxillary sinus with usage of osteoplastic materials. A clinical case of lateral (open) sinus-lifting performed by "grind-out" technique with the DASK® kit (Dentium Advanced Sinus Kit®) is described. As an osteoplastic material was used an alloplastic self- hardening in wound material easygraft®.

Metropolis cities like Moscow, have a very important part in social and economic growth of countries like Russia for example. But neglecting environmental resources and the impact on climate change have become a serious challenge for realization of the contribution which those big cities can make on economic development of the countries. This article contains a technical suggestions how to reduce the negative environmental consequences of the daily life of the megalopolis, new technological methods of urban planning and landscape architecture are being implemented all over the world. This article considers the new environmental methods and best foreign practices for the transition towards sustainable cities. Further described the possibility of using innovative technology of green roofs especially for Moscow region. The article is considering green roofs as a very effective mechanism for reducing the heat island effect and for “precipitation management”. This article gives a short overview of the European expertise of using green roofs for climate-change-adaptation measure and gives recommendations to Russian environmental policies.

The technique of copper filling of trenches which is based on the effect of the melting temperature decrease, depending on film thickness reduction, has been proved and demonstrated experimentally. An approach to diffusion barrier creation is proposed. Ta-W-N amorphous alloy has been selected as the barrier material for copper. This barrier layer keeps its properties in the Cu/Ta-W-N/TiSi2/Si structure up to 800 °C, and in the Cu/Ta-W-N/SiO2 structure up to 850 °C. The temperature for copper filling of the trenches is shown to be significantly lower than the temperature of bulk copper melting, and to depend on the thickness of the film. It is determined that this effect is caused not only by the lowering of the phase changing temperature as a result of the thinning of the film, but also by the system tendency to optimize its form by the change in the ratio of the surface and volume energies. When the thickness is 50 nm the temperature of filling is 750 °C, when it is 100 nm – 850 °C. However, this temperature reduction is not enough for use of the presented approach in UVLI technology, and further development of this approach is required, including possible combination with other filling methods.

An etch-stop phenomenon taking place in Cl2/O2/N2 plasma was investigated by means of the actinometry technique as well as using PlasmaVolt and PlasmaTemp in-situ sensor wafers from K-T promesys of KLA Tencor. The temperature of TCP quartz window was determined to increase from 50°C to more than 100°C during sequential plasma processing that in turn induces a plasma composition change. Based on the optical spectra a 20% increase in both atomic [O] and [Cl] concentrations was determined to take place in Cl2/O2/N2 plasma used for STI etching. Performing experiments on the blanket wafers the dependence of the etch-stop on O2-flow, pressure, TCP power, wafer temperature and quartz window temperature was determined. The values of RF voltage and temperature were measured locally at different positions on the wafer surface providing additional information about plasma homogeneity. Finally, the results are discussed in terms of the well-known recombination model considering the increase of [O] concentration results in the etch stop in the middle of the wafer.© (2008) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

It is shown that copper thin film conductors (10-100 nm thickness) have not the defined temperature of melting. The melting of 20 nm copper thin film starts at 610 °C after 5 mm and, at the same time, at 470 °C after 3 h 40 mm. The melting of 100 nm copper thin film starts at 740 °C after 7 mm and at 640 °C after 2 h 25 mm. The kinetics of this phenomenon has been studied. The stages of process have been shown. The activation energies of thin film melting have been estimated. It is demonstrated that the activation energy of process is decreased with the copper film thickness reduction. The character of activation energy changes has been explained with point of view of the hydrodynamics.

The combined method of trench filling by copper for damascene technology has been developed. The method is based on copper deposition by ordinary electroplating and following low temperature melting of copper layer. The thickness of wetting layer has been optimized. The importance of seed layer surface treatment is demonstrated. It is shown that the thermal annealing at 650oC allows to dispose of voids appearing at copper electrochemical deposition into trenches.© (2006) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.