The influence of Pb vacancies on the properties of PZT-type ceramics transducers

This article is dedicated to prof. J. Ranachowski The result of investigations of the influence of lead vacancies on the crystalline structure of PZT-type ceramic piezoelectric materials is presented. The solid solution of PbTiO3 - PbZrO3 - sigma n=13 Pb(B'1-alpha B''alpha)O3, characterized by the perovskite-type structure (ABO3), is the basis of those materials. The lead vacancies (VPb) was originated by a thermal treatment. Investigations of the influence of the lead deficiency on the crystalline structure of PZT-type ceramics have been performed for solid solutions characterized by compositions corresponding to the tetragonal or rhombohedral boundary of the morphotropic region (PCR-1, PCR-8: Piezoelectric Ceramics of Rostov) and to tetragonal phase region compositions (ceramics of Pb1-x(Zr0.39Ti0.59W0.01Cd0.01) O3). It has been found that the deficiency in lead causes a reconstruction of the perovskite phase crystalline structure or a change of the elementary cell parameters of that phase. The solid solutions on the basis of Pb(Zr,Ti)O3 resolve themselves into PbTiO3, ZrO2 and PbO when the lead deficiency caused by thermal treatment increases

Review on uranium in soil: levels, migration

The problems of radioactive contamination of biosphere with the 238U in recent years have attracted a large number of experts in various fields of knowledge. Natural radionuclides are an integral part of the biosphere. They are concentrated everywhere: in rocks, in soil, water, air and food. Various types of phosphorus fertilizers and other natural ameliorants used in agriculture are also an additional source of heavy natural radionuclides. The review describes the behaviour and migration of 238U in biosphere, which depend on various factors acting simultaneously. It is noted that the behaviour of 238U in the soil depends on the forms of its presence in it and the physical and chemical properties of the soil. The processes of sorption and desorption of 238U by different soil types are significant indicators

Pressure effect on the in-plane magnetic penetration depth in YBa_2Cu_4O_8

We report a study of the pressure effect (PE) on the in-plane magnetic field penetration depth lambda_{ab} in YBa_2Cu_4O_8 by means of Meissner fraction measurements. A pronounced PE on lambda_{ab}^{-2}(0) was observed with a maximum relative shift of \Delta\lambda^{-2}_{ab}/\lambda^{-2}_{ab}= 44(3)% at a pressure of 10.2 kbar. It arises from the pressure dependence of the effective in-plane charge carrier mass and pressure induced charge carrier transfer from the CuO chains to the superconducting CuO_2 planes. The present results imply that the charge carriers in YBa_2Cu_4O_8 are coupled to the lattice.Comment: 4pages 3 figure

SYSTEM OF ANAESTHETIC SUPPORT AT LARGE JOINT REPLACEMENT SURGERIES

The operation of total endoprosthesis replacement of large joints is associated with several anesthetic problems. Solving these problems ensures the safety of these highly traumatic operations and requires the solution of the following anesthetic tasks in the perioperative period: high degree of antinociceptive protection of patients with effective relaxation of the surgical intervention area; prevention of fatty hyperglobulinemia; decrease in the volume of perioperative hemorrhage and prophylaxis of thrombogenic complications. We developed our own program of anesthetic maintenance at major joints replacement. The components of the program are: the type of anesthesia - spinal anesthesia preservation of spontaneous respiration; our method of fat globulinemia prevention, based on maintaining the functional stability of the hepatocyte; our own method of replacement of peri-operative blood loss, based on the additional principle of "normalization of the oncotic blood pressure". Before the operation, patients receive a solution of tranexamic acid at a dose of 10 mg/kg of body mass to inhibit proteolysis (blood preservation technology). This method provides a "dry" operating field, reducing intraoperative hemorrhage. In the early postoperative period (5 hours after the surgery), under the control of whole blood clotting time, patients receive low molecular weight heparin Clexane at a therapeutic dosage of 1 mg/kg of body weight. This provides effective prevention of thrombogenic complications. The application of the developed technique shows its high clinical effectiveness. Over the past 5 years, 5,800 operations for large joint prosthetics have been performed, including 3,200 total hip replacement operations, 2,600 total knee replacement operations. There were no complications with a fatal outcome, in 5 cases fatty hyperglobulinemia was noted, which was stopped by the own method of treatment. There are no thrombogenic complications

Neurons Controlling Aplysia Feeding Inhibit Themselves by Continuous NO Production

Neural activity can be affected by nitric oxide (NO) produced by spiking neurons. Can neural activity also be affected by NO produced in neurons in the absence of spiking?Applying an NO scavenger to quiescent Aplysia buccal ganglia initiated fictive feeding, indicating that NO production at rest inhibits feeding. The inhibition is in part via effects on neurons B31/B32, neurons initiating food consumption. Applying NO scavengers or nitric oxide synthase (NOS) blockers to B31/B32 neurons cultured in isolation caused inactive neurons to depolarize and fire, indicating that B31/B32 produce NO tonically without action potentials, and tonic NO production contributes to the B31/B32 resting potentials. Guanylyl cyclase blockers also caused depolarization and firing, indicating that the cGMP second messenger cascade, presumably activated by the tonic presence of NO, contributes to the B31/B32 resting potential. Blocking NO while voltage-clamping revealed an inward leak current, indicating that NO prevents this current from depolarizing the neuron. Blocking nitrergic transmission had no effect on a number of other cultured, isolated neurons. However, treatment with NO blockers did excite cerebral ganglion neuron C-PR, a command-like neuron initiating food-finding behavior, both in situ, and when the neuron was cultured in isolation, indicating that this neuron also inhibits itself by producing NO at rest.Self-inhibitory, tonic NO production is a novel mechanism for the modulation of neural activity. Localization of this mechanism to critical neurons in different ganglia controlling different aspects of a behavior provides a mechanism by which a humeral signal affecting background NO production, such as the NO precursor L-arginine, could control multiple aspects of the behavior