Stability Analysis and Hopf Bifurcation for ODE System of Predator-Prey Model with Mutual Interference

In this paper, the temporal and spatial patterns of a diffusive predator-prey model with mutual interference under homogeneous Neumann boundary conditions were studied. Specifically, first, taking the intrinsic growth rate of the predator as the parameter, we give a computational and theoretical analysis of Hopf bifurcation on the positive equilibrium for the ODE system. As well, we have discussed the conditions for determining the bifurcation direction and the stability of the bifurcating periodic solutions.

Uniqueness of Positive Radial Solutions for a Class of Semipositone Systems on the Exterior of a Ball

In this paper, we study the positive radial solutions for elliptic systems to the nonlinear BVP: , where Δu = div (∇u) and Δv = div (∇v) are the Laplacian of u, λ is a positive parameter, Ω = {x ∈ Rn : N > 2, |x| > r0, r0 > 0}, let i = [1,2] then Ki :[r0,∞] → (0,∞) is a continuous function such that limr→∞ ki(r) = 0 and is The external natural derivative, and : [0, ∞) → (0, ∞) is a continuous function. We discuss existence and multiplicity results for classes of f with a) fi > 0, b) fi < 0, and c) fi = 0. We base our presence and multiple outcomes via the Sub-solutions method. We also discuss some unique findings.

Global Bounded Solutions for the Keller-Segel Chemotaxis System with Singular Sensitivity

In this paper, we consider the Neumann initial-boundary value problem for the Keller-Segel chemotaxis system with singular sensitivity (0.1) is considered in a bounded domain with smooth boundary, Ω ⊂Rn (n ≥ 1), where d1 > 0, d2 > 0 with parameter χ ∈ R. When d1 = d2 + χ, satisfying for all initial data 0 ≤ n0 ∈ C0 and 0 < v0∈ W1,∞ (Ω), we prove that the problem possesses a unique global classical solution which is uniformly bounded in Ω × (0, ∞).

Pure SnO₂Gas Sensor with High Sensitivity and Selectivity towards C₂H₅OH

To observation, poisonous gases in the environment, Sensors with high selectivity, high response and low operating temperature are required. In this work, pure SnO2 nanoparticles was prepared by using a simple and inexpensive technique (hydrothermal method) without a template. Various confirmatory tests were performed to characterize SnO2 nanoparticles such as energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Transition Electron Microscopy (TEM), during the detection of the gas, we found that pure SnO2 nanoparticles has a high selectivity for ethanol to 100 ppm at a low temperature (180°C) and a high response (about 27 s) and a low detection limit of 5 ppm, also it have response/recovery times about (4 s, 2 s) respectively. The distinctive sensing properties of SnO2 sensor make it a promising candidate for ethanol detection. Furthermore, the gas-sensing mechanism have been examined.

The Role of Agricultural Extension in Decentralizing the Sensitivity of Vegetable Farmers to the Risk of Residual Pesticide Effects

This study was carried out in the northern Khartoum (Bahry Locality) with the aim of knowing the role of agricultural extension in developing the awareness of the farmer to the danger of residual effect of pesticides (vegetable farmers). The social survey method was used to conduct this study;100 vegetable farmers were selected randomly. The data collected through questionnaires, observation, and interviews for primary data, previously concerned, and reference documents were used to collect secondary data. Data collected were analyzed using the statistical packages for social science (SPSS). The study yielded some useful results, the most important of which are: the presence of respondents who obtain their information about pesticides from merchants, the absence of a guide provider in their area, and the absence of any seminars or lectures on the use of pesticides, or programs. For example, radio and television programs were presented but protective clothing was not used. This study is based on the researcher's advocate for the following: intensifying agricultural extension and employee visits to the agricultural field, in addition to intensifying educational evidence for consumers regarding pesticides and providing preliminary data on pesticides and how to deal with them and increase them. Educate farmers about the safe use of pesticides and identify the risks and damages that pesticides cause to humans.

Synthesis and Characterization of SnO<SUB>2</SUB>Flower-Shaped by Hydrothermal Route for Formaldehyde Sensing Properties

In this work, we’ve made SnO2 flower formed with the aid of using easy test steps, and without cost, which is the hydrothermal approach and without a template. We have used a variety of techniques to characterize SnO2 flower-shaped by (SEM, TEM, XRD, BET and XPS) instruments. Confirmatory tests carried out have proven that the surface of the tetragonal structure of SnO2 has a rough surface which makes it excellent for its gas-sensing properties. The gas detection test of SnO2 flower-shaped proved that it possesses the selectivity of formaldehyde gas (about 30), the optimum operating temperature of the sensor is 220°C, and also the sensor has a high response time and recovery time is (5 s and 22 s) to 100 ppm, respectively. Particularly, the sensor has an obvious response value (2) when exposed to 5 ppm formaldehyde. As well, the mechanism of gas-sensing was also discussed.