PHYTOREMEDIATION OF URANIUM TAILINGS: ROLE OF CHELATORS IN TRIGGERING URANIUM ACCUMULATION IN WHEAT

Chelator-assisted phytoextraction has been proposed as a potential tool for phytoremediation of uranium contaminated tailings. The purpose of the present investigation was to test the efficiency of the four various chelators namely, citric acid (CA), oxalic acid (OA), NTA and EDTA and to screen out the most effective chelator with promising concentration of it in increasing the U uptake and accumulation for phytoremedial programmes. Three kilograms of mixture (25:75; tailing: garden soil) was filled in the earthen pots. Treatment pots were prepared by applying- 0.1, 0.5, 2.5 and 12.5 mmol kg-1 concentrations of each of the chelator (CA, OA, NTA and EDTA). Optimum concentrations of the chelators were recorded considering biomass production, tolerance index and U uptake. Each chelator produced severe toxicity symptoms at 12.5 mmol kg-1 treatment level. Lowest depression in respect of growth was observed with NTA while OA and CA were proved less toxic than EDTA. Highest inhibition was recorded in EDTA treatments at respective levels. U uptake and accumulation was concentration dependent for each of the chelator amendment. Maximum U uptake (3.4-fold) in the roots occurred at 2.5 mmol kg-1 of CA while NTA proved to be the weakest for the same purpose. Not with standing, EDTA and NTA are stronger complexion agents than CA but in contrary, the use of CA proved beneficial in U tailing phytoremediation in the present investigation. The growth of the wheat plants was affected by each of the chelator, which in general follows the order: NTA ? OA ? CA ? EDTA, whereas the order for U accumulation was recorded as- CA > EDTA > OA > NTA. On the basis of this study it can be suggested that the use CA over EDTA is better, as it is easily biodegradable, less toxic and has lower leaching risk..

An Integrated Evanescent Field Sensor for the Simultaneous Measurement of Layer Refractive Index and Thickness

A novel integrated sensor for the simultaneous measurement of layer refractive index and thickness based on evanescent fields is proposed. The theoretical limits for the accuracy of the sensor were examined for the example of a TiO2 layer. The influence of production tolerance on the accuracy was evaluated. In the experimental part of this work, a sensor chip containing nanowire and nanorib waveguides realized in silicon on insulator technology was used to demonstrate the detection of refractive index and thickness of a TiO2 atomic layer deposition (ALD) layer.

Dimensional variability of orthodontic slots and archwires: an analysis of torque expression and clinical implications

Background The loss of third-order information in pre-adjusted brackets due to torsional play is a problem in clinical orthodontics. The aim of this study was to evaluate the impact of slot height, archwire height, width and edge bevel’s radius on the torsional play for three brackets/archwire systems. Methods Ninety brackets with a 0.022 × 0.028 in. slot with McLaughlin-Bennett-Trevisi prescription from three different manufacturers were selected, and the slot’s height and depth were measured using a profile projector. Sixty stainless-steel rectangular archwires from three different manufacturers were sectioned and observed with a SEM to measure their height, width, and radius of edge bevel. The recorded data were used to calculate the theoretical torsional play between different slot−archwire combinations. One-way ANOVA was used to compare the measurements within different bracket types and among different manufacturers. Results Slot height was usually oversized. Archwire’s height was usually undersized, but oversized wires were also observed. The radius edge bevel was the most variable parameter. A certain degree of torsional play is always present that differs from one bracket type to another of the same producer and that can even be doubled from one manufacturer to another. Conclusions Due to production tolerance, differences between the nominal values and the real dimensions of any components of a slot/archwire system are common. This results in a torsional play that limits torque expression. The archwire’s edge bevel plays an important role in torque expression, and clearer information should be provided by the manufacturers regarding this aspect.

Extending the Production Tolerance of a Gauge and Determining its Trueness

Gauges are widely used means for alternative control in mass production and, in some cases, in small-scale production. Similar to all measuring devices, their use is accompanied by the well-known errors Type I (α) and Type II (β). A basic requirement when designing gauges is that the values of these errors are equal to those of other measuring devices. Considering the development and improvement of technological processes, at present there is a real possibility to improve some of the gauges’ characteristics. The most important metrological characteristic of the conical gauge is the so-called base distance. The standardized design requirements that are introduced to prevent scrap significantly reduce the production tolerance of the gauge. This not only causes some difficulties in the production of gauges, but also increases the likelihood of incorrectly rejecting conforming parts. The paper presents an opportunity to extend the production tolerance of conical gauges by applying a novel way of determining the nominal diameter of its no-go part, and by calculating theoretically the associated risk Type I (α).

Determination of the parameters of typical multi-link dimensional chains (closing link is tension) using recurrent dependencies

The existing approach to the use of the group interchangeability method during assembly, which are concentrated, has a number of significant drawbacks: 1) there are no formulas for calculating the upper and lower deviations of the component parts of the dimensional chain; 2) deviations are selected without taking into account the design of the component links (the method of equal tolerances is used); 3) the method is applicable for the number of links no more than three with a small number of groups. For other types of problems there is no algorithm, mathematical apparatus, and examples of calculation are not considered sequentially; 4) the calculation by the group interchangeability method is limited by the condition of equal tolerances, i.e. excluding compensators and compensating properties of materials as a part of mechanisms; 5) the calculations are based on assumptions about the economic feasibility of increasing the closing link by a factor of n without taking into account the feasibility of such an increase in the component links that is not permissible in complex mechanisms; 6) the size of the batch of parts and the volume of work in progress are not reflected, as one of the factors of economic feasibility of establishing production tolerance. In this regard, it is necessary to improve the method of achieving accuracy by group interchangeability. This article discusses typical problems that rise when solving dimensional chains in which the closing link is a tension.

Instrument accuracy influence on kinematics of rotary traverse of axial gear set with horizontal jet thrust in a group tractive drive of a lokomotive

Objective: To obtain analytical responses of linear and angular movements of horizontal jet thrust and axial reduction unit, appearing in the process of their production and group tractive drive assembly, occurring as a result of vertical wheelset and engine’s undercarriage frame shifts during engine movement. The given responses are the basis for identifying its velocity, acceleration, and dynamic loads on drive components, as well as searching for methods to boost drive components reliability, taking into account its constructive specificities and running conditions. Methods: Analytical responses were identified on the basis of higher mathematics, the laws of theoretical mechanics as well as trigonometry knowledge application. Results: Analytical responses of kinematic spatial movements of horizontal jet thrust and an axial reduction unit with instrument accuracy of a group tractive drive were obtained from vertical engine’s undercarriage frame shifts and locomotives wheelset. Boundary conditions of jet thrust slopes were detected, as well as center lines of axial reduction units. The analysis of established relations was performed. Possible scheme variants of spatial movements of horizontal jet thrust and a wheel set axial reduction unit in engine’s undercarriage frame were presented with possible discrepancies of linear dimensions from production tolerance. Characteristic curves of vertical shifts of actual towline constructions from vertical shifts of undercarriage frame during locomotive’s movement were graphed. Practical importance: On the basis of obtained relations the analysis of linear displacement, angular velocities and accelerations of jet thrusts and wheel set axial reduction units is possible, as well as the generation of rational and robust wheel set cardan tractive gear constructions for locomotives with minimal dynamic load on its elements. The results of analytical research might be applied in the designing of new engines with high dynamic parameters.

A Laboratory Assessment of Two Local Strains of the Beauveria bassiana (Bals.) Vuill. against the Tetranychus urticae (Acari: Tetranychidae) and Their Potential as a Mycopesticide

This study was conducted to assess highly pathogenic Beauveria bassiana isolates to be used in biocontrol and to determine their potentials as mycopesticide. For this purpose, two B. bassiana isolates, which were locally isolated from T. urticae, were chosen. Firstly, three suspensions were investigated at the degree of humidity of 65 ± 5% and 100% RH. Secondly, these strains were selected according to their tendency to mass production, tolerance to UV radiation, and capability of producing spore at the different temperatures. Finally, identification of the selected isolate was performed by using ITS rDNA analysis. Both tested fungal isolates were pathogenic to the T. urticae. Mycelial growths of isolate AT076 at 20°C and 30°C were found to be greater than isolate AT007. It was observed that isolate AT076 had more spore production with 1.61 × 107 spore/disc at 30°C and 44.33% germination after UV radiation for 15 min. The numbers of spores per 5 mm disk area for isolates AT076 and AT007 were found to be 1.2 × 106 and 1.0 × 106. These results show that isolate AT076 was more virulent and more UV-tolerant and had higher tendency to mass production compared to isolate AT007 against T. urticae. As a result of this study, isolate AT076 can be used in the biocontrol as mycopesticide.