Experimental studies to study the efficacy of "Tarzan, VE" against Blattoptera representatives

The purpose of the research is studying the efficacy of "Tarzan, VE" against representatives of the Blattoptera order, Blattella germanica.Materials and methods. Experimental studies to study the efficacy of "Tarzan, VE" on representatives of the Blattoptera order were performed for two weeks at the premises of the Skryabin MVA (Moscow) and the KemSMU (Kemerovo). The study object was the red German cockroach B. germanica, a laboratory culture of which was grown in the MVA insectarium. Experiments 1 and 2 consisted of three tests of three sets each: a test to study the efficacy of the drug against cockroaches by the topical application; and a test to study the efficacy of "Tarzan, VE" against cockroaches by the forced exposure of arthropods to test surfaces, namely, plywood or glass previously treated with the drug in different concentrations. Dead insects were counted after a day.Results and discussion. We established the efficacy of "Tarzan, VE" in the form of an active substance in different dilutions against cockroaches B. germanica of both sexes using the topical application. Its efficiency decreases to 97% when diluted 1000 times (0.001N). With forced exposure to treated test surface (plywood), the efficacy of “Tarzan, VE” depended on the substance diluted: 90% at 0.01N, 83.3% at 0.005N, and 50% at 0.001N. The maximum effect of "Tarzan, VE" was observed when using the method of forced exposure of cockroaches to the treated test surface, glass. The efficacy of the drug in this case was 100% regardless of the sex and development stage of cockroaches. It was found that different concentrations of the insecticide had a toxic effect on the imago of both sexes and larval stages of cockroach development. The insecticidal nature of the drug is ensured by the use of zeta-cypermethrin as an active ingredient. "Tarzan, VE" insecticide can be recommended to control and prevent the distribution of B. germanica.

Influence of nanosized particles of zirconium and aluminum oxides on the properties of materials based on the Si-B4C-ZrB2 composition

The effect of nanosized particles of ZrO2 and Al2O3 on physicomechanical properties (elastic modulus, flexural strength, microhardness), phase composition, and also the microstructure of materials based on Si-B4C-ZrB2 is studied. After heat treatment in air in an electric furnace, a borosilicate glass-forming melt was obtained by a reaction method, which had an encapsulating effect on the starting components. As a result, gradient glassceramic materials were obtained in which the surface glass-ceramic layer protects the underlying layers from oxidation. This approach can be used to obtain protective coatings for carbon materials. It is shown that the introduced additives improve the mechanical properties of the composites.

Delamination mechanism of GFRP sheet bonded on the reinforced concrete beams

Fiber reinforced polymer (FRP) has been developed to be applied for a strengthening of the deteriorated structures. In the form of a sheet, the FRP may be applied for the strengthening of the structures by bonding it to the concrete surface. Glass composed FRP (GFRP) sheet is most commonly used due to its relatively lower cost compared to the other FRP materials. GFRP sheet is applied externally by bonding it on the concrete surface. The strengthened structures should be monitored periodically to ensure the health of the strengthened structures. Regarding the development of monitoring system of the strengthened structure, it is important to study the delamination phenomenon of the bonded GFRP. Therefore the delamination mechanism is important to be clarified. Many studies have been done to investigate the bonding characteristics of GFRP sheet under direct tensile loading. However, the studies on the bonding characteristics of GFRP sheet on the strengthened beams due to flexural loadings are still limited. A series of concrete beams strengthened with GFRP sheet on extreme tension surface were prepared. The beam specimens ware loaded under four-point bending test gradually up to the ultimate capacity. Results indicated that prior to final delamination, a local delamination occurred which was indicated by the suddenly decreasing of an applied load. The delamination of the GFRP sheet may be initiated by the flexural cracks occurred on the beams.

Graded Ultra-Translucent Zirconia (5Y-PSZ) for Strength and Functionalities

Ultra-translucent zirconias are drawing immense attention due to their fascinating esthetic appearance. However, the high translucency came at the expense of diminishing strength along with the reduced ability of transformation toughening due to the increased cubic zirconia content. We aim to address these issues by infiltrating glass on the surface of an ultra-translucent zirconia (5Y-PSZ). Glasses of different shades can be used and the resulting graded glass/zirconia layer is expected to improve the material’s flexural strength without compromising its esthetics. We also aim to elucidate how clinically relevant surface treatments—namely, air abrasion, glazing, or polishing—affect the fracture resistance of these zirconias with a high cubic content. All surface treatments were performed on bar-shaped (2 × 3 × 25 mm3) and plate-shaped (12 × 12 × 1 mm3) specimens, which were then subjected to a 4-point bending test and translucency measurements, respectively. 5Y-PSZ proved to be significantly more translucent than 3Y-TZP but also much weaker. Our hypothesis was accepted, as the strength of the glass-infiltrated ultra-translucent 5Y-PSZ (582 ± 20 MPa) is over 70% higher than its uninfiltrated counterpart (324 ± 57 MPa). Its strength is also over 25% higher than the highly polished 5Y-PSZ (467 ± 38 MPa). In addition, the translucency of 5Y-PSZ (translucency parameter [ TP] = 34, contrast ratio [ CR] = 0.31) is not affected by glass infiltration ( TP = 34, CR = 0.32) when the residual surface glass is removed by gentle polishing using 6- and then 3-µm diamond grits. Finally, both air abrasion and the presence of a glaze layer on the tensile surface decreased flexural strength significantly, being 274 ± 55 and 211 ± 21 MPa, respectively. With a combined high strength and translucency, the newly developed glass-infiltrated 5Y-PSZ may be considered a suitable material for next-generation, damage-resistant, and esthetic dental restorations.