First Evaluation of Field Evolved Resistance to Commonly Used Insecticides in House Fly Populations from Saudi Arabian Dairy Farms

The house fly, Musca domestica L. (Diptera: Muscidae), is one of the major vectors of several pathogens that affect humans and animals. We evaluated the toxicity of eight insecticides commonly used for house fly control using five field populations collected from dairies in Riyadh, Saudi Arabia. Among the five tested pyrethroids, non to moderate resistance was found in adults of both sexes compared to a susceptible strain. Resistance ratios ranged from 0.5- to 7-fold for alpha-cypermethrin, 2- to 21-fold for deltamethrin, 4- to 19-fold for bifenthrin, 1- to 9-fold for cyfluthrin, and 1- to 8-fold for cypermethrin. Among the three tested organophosphates, low to moderate resistance was found among adult flies compared to the susceptible strain, and the resistance ratios ranged from 4- to 27-fold for fenitrothion, 2- to 14-fold for chlorpyrifos, and 3- to 12-fold for malathion. The median lethal times for the tested insecticides were 3–33 h for alpha-cypermethrin, 3–24 h for deltamethrin, 5–59 h for bifenthrin, 1–7 h for cypermethrin, 0.3–7 h for cyfluthrin, 6–36 h for fenitrothion, 2–21 h for chlorpyrifos, and 3–34 h for malathion. This study presents baseline data pertaining to registered public health insecticides, and the results will assist future studies monitoring insecticide resistance, and the planning of effective integrated vector management programs.

Biocompatible and Enzymatically Degradable Gels for 3D Cellular Encapsulation under Extreme Compressive Strain

Cell encapsulating scaffolds are necessary for the study of cellular mechanosensing of cultured cells. However, conventional scaffolds used for loading cells in bulk generally fail at low compressive strain, while hydrogels designed for high toughness and strain resistance are generally unsuitable for cell encapsulation. Here we describe an alginate/gelatin methacryloyl interpenetrating network with multiple crosslinking modes that is robust to compressive strains greater than 70%, highly biocompatible, enzymatically degradable and able to effectively transfer strain to encapsulated cells. In future studies, this gel formula may allow researchers to probe cellular mechanosensing in bulk at levels of compressive strain previously difficult to investigate.

RESISTANCE AND STRAIN RESISTANCE PROPERTIES OF SOLID SOLUTIONS TLIN1-XCOXSE2 (0 ≤ X ≤ 0.5)

The paper presents the results of a study of the effect of the ratio of cobalt components on the electrophysical and strain-resistive characteristics Of tlin1-xcohse2 alloys in the concentration range of cobalt x = 0-0.5. it is established that in the range of x = 0 — 0.02 these properties have linear concentration dependencies, which undergo sharp changes in the range of 0.02 — 0.5.

Rheological Properties and Microstructure of PH1 Stainless Steel Produced by Selective Laser Melting

The present study is focused on rheological properties of PH1 stainless steel, produced by selective laser melting (SLM), at temperatures of hot deformation, with the aim to investigate the dependence of strain resistance on temperature and strain degree. The tests of cylindrical specimens, made of PH1 stainless steel, were carried out using a cam plastometer in temperature range 700 – 1200 °C at a strain rate ξ equal to 1 s-1 up to strain degree e equal to 0.8 – 1.2. The paper presents the results of investigation of initial microstructure, microhardness measurement and flow curves of PH1 steel, produced by SLM method. The flow curves of PH1 steel produced by SLM can be used in the development of new methods of manufacturing the metallic parts by additive technologies with the use of deformation post-processing.

Verification of a New Torsion Test Method to Study the Rheological Properties of Materials in a Cold State

The most important parameter, characterizing the rheological properties of steels and alloys, is the strain resistance. The new method of testing cylindrical specimens for torsion with variable grip’s accelerations is proposed (application No. 2018132149 of 07.09.2018 for the patent of the Russian Federation for the invention). This method is designed to study the rheological properties of steels and alloys mainly in a hot state. However, this method is universal and can be used to determine strain resistance of materials in a cold state. The article is devoted to the applicability evaluation of the proposed torsion testing method, to study the rheological properties of materials in a cold state. It’s done on the basis of comparison of the hardening curves, obtained during the testing of specimens for tensile and torsion. The CrWMn steel was used. The results show that the hardening curves obtained during the torsion and tensile tests are close, and the yield stress values differ by about 3%. It can be assumed that the developed method of torsion testing allows to obtain reliable values of the material’s strain resistance in a cold state.

Measuring of deformations and forces in rod elements using a micrometer

The study of the stress-strain state (SSS) gives an indication how structural elements work in real operating conditions. The purpose of this study was to analyze the existing methods used for monitoring of buildings and structures, as well as to create a universal, inexpensive, and simple method for measuring deformations and forces in rod elements using a micrometer. As the results of laboratory tests have shown, the new method is in no way inferior to the existing electric, acoustic and strain resistance methods of SSS control, surpassing them in some parameters, such as ease of installation, mobility, security, cost-effectiveness. The accuracy of measuring forces up to 7 % assessed during laboratory tests confirms the possibility of using this method for monitoring of existing structures.