AGGREGATE STABILITY AND WATER RETENTION NEAR SATURATION CHARACTERISTICS AS AFFECTED BY SOIL TEXTURE, AGGREGATE SIZE AND POLYACRYLAMIDE APPLICATION

Understanding the effects of soil intrinsic properties and extrinsic conditions on aggregate stability is essential for the development of effective soil and water conservation practices. Our objective was to evaluate the combined role of soil texture, aggregate size and application of a stabilizing agent on aggregate and structure stability indices (composite structure index [SI], the and n parameters of the VG model and the S-index) by employing the high energy (0-5.0 J kg(-1)) moisture characteristic (HEMC) method. We used aggregates of three sizes (0.25-0.5, 0.5-1.0 and 1.0-2.0 mm) from four semi-arid soils treated with polyacrylamide (PAM). An increase in SI was associated with the increase in clay content, aggregate size and PAM application. The value of increased with the increase in aggregate size and with PAM application but was not affected by soil texture. For each aggregate size, a unique exponential type relationship existed between SI and . The value of n and the S-index tended, generally, to decrease with the increase in PAM application; however, an increase in aggregate size had an inconsistent effect on these two indices. The relationship between SI and n or the S-index could not be generalized. Our results suggest that (i) the effects of PAM on aggregate stability are not trivial, and its application as a soil conservation tool should consider field soil condition, and (ii), n and S-index cannot replace the SI as a solid measure for aggregate stability and soil structure firmness when assessing soil conservation practices

The Penning Discharge Experimental Study and Its Simulation

The influence of the demountable Penning ion source electrodes geometry on the discharge characteristics and extracted ion current is investigated. The extracted currents, ignition potentials and the operational pressure ranges are compared at different anode heights and its arrangement relative to the discharge cell. The use of ring and mesh anodes has allowed to visualize the discharge burning areas and their structure versus the pressure, anode potential and cell geometry. Some PIC simulations of Penning discharge are made in the Vorpal code. The good correspondence between the simulated electron density and plasma glow areas on the photos is shown. The other one-particle simulation has shown that the magnetic field nonuniformity significantly affects the ignition and combustion discharge potentials

Opening of a pseudogap in a quasi-two dimensional superconductor due to critical thermal fluctuations

We examine the role of the anisotropy of superconducting critical thermal fluctuations in the opening of a pseudogap in a quasi-two dimensional superconductor such as a cuprate-oxide high-temperature superconductor. When the anisotropy between planes and their perpendicular axis is large enough and its superconducting critical temperature T_c is high enough, the fluctuations are much developed in its critical region so that lifetime widths of quasiparticles are large and the energy dependence of the selfenergy deviates from that of Landau's normal Fermi liquids. A pseudogap opens in such a critical region because quasiparticle spectra around the chemical potential are swept away due to the large lifetime widths. The pseudogap never smoothly evolves into a superconducting gap; it starts to open at a temperature higher than T_c while the superconducting gap starts to open just at T_c. When T_c is rather low but the ratio of varepsilon_G(0)/k_BT_c, with varepsilon_G(0) the superconducting gap at T=0K and k_B the Boltzmann constant, is much larger than a value about 4 according to the mean-field theory, the pseudogap must be closing as temperature T approaches to the low T_c because thermal fluctuations become less developed as T decreases. Critical thermal fluctuations cannot cause the opening of a prominent pseudogap in an almost isotropic three dimensional superconductor, even if its T_c is high.Comment: 25 pages, 5 figures (14 subfigures

Fuzzy-Logical model for analysis of sustainable development of fuel and energy complex enterprises

The purpose of this article is to build a mathematical model for analyzing the sustainability of the development of an enterprise in the fuel and energy complex, integrated into an information management syste

Analysis of the effectiveness of stenting the duct of the pancreas in patients with impacted stones of the major duodenal papilla

Purpose: to evaluate the impact of stenting of the pancreatic duct on the course of biliary pancreatitis for patients with impacted stone of major duodenal papilla.Materials and methods: A retrospective analysis of the treatment of 90 patients with impacted stone of major duodenal papilla that underwent endoscopic interventions on the major duodenal papilla in 1/3 of cases accompanied by the installation of a stent of the pancreatic duct. Depending on the stenting, the patients were divided into two groups - the first group (n = 31 patients) with the stented pancreatic duct, the second group (n = 59 patients) - without stent placement. The groups were compared by the dynamics of changes and the normalization time of laboratory indicators, sonographic signs of biliary and pancreatic hypertension before and after the intervention.Results: Following differences were observed: in the group of stented patients the hyperamylasemia has reduced with the period of normalization of amylase 1.5 times less (p = 0.005) , decrease of amylase at the stented patients with signs of pancreaticectasia at ERCP by 55.6% comparing to the patients without stent - 7.1% (p = 0.005). Laboratory signs of development of post-ERCP pancreatitis were noted in 6.5% of stented and 11.9% of non-stented patients. The average hospitalization time in the first group was 11.5 ± 4.1 days and in the second - 15.5 ± 9.6 days (p = 0.032).Conclusion: Stenting the pancreatic duct in patients with impacted stone of major duodenal papilla reduces the risk of postmanipulation pancreatitis, speeds up the normalization of laboratory markers of acute biliary pancreatitis, reduces the time of hospitalization of this category of patients, has not only a preventive but also therapeutic effect