Avaliação da exposição ocupacional ao mercúrio num grupo de cirurgiões-dentistas da unidade sede do Sesc de Porto Alegre

The aim of this study was to analyse the data obtained from a structured questionaire, and the mercury levels found in the urine of 5 1 dental-surgeons at the SESC headquarters in Porto Alegre in 1997. The analysis of data showed that dental-surgeons had occupational exposition to mercury, whereas most of them showed levels of mercury above the reference value of normality, which is 5ug/g creatinine, despite of this, it is still lower than the maximum allowable level which is 35ug/g creatinine.

QUALITY INDICATORS AND VETERINARY ANALYSIS OF CATFISH MEAT WHEN USING THE FOOD ADDITIVE «RIZOSTIM»

The article presents research data on the chemical composition and content of toxic elements in the meat of fish grown in the pools of «ASYL TAS ENGINEERING» LLP, Almaty region, when using «Risostim» feed additive. Researches with comparison of the samples taken from fish - catfish at use of a food additive «Risostim» and a carp in a comparative aspect were carried out. In the course of the study it was found that the fat and moisture content of catfish meat was higher, while the protein and ash content was lower. It was also found that the amount of toxic elements did not exceed the maximum allowable level. It follows from this that catfish meat grown in pools of «ASYL TAS ENGINEERING» LLP of Almaty region, when using feed additives «Risostim» is a benign and safe food product.

Sand-sodium-silicate mixtures grains composition optimization for structuring by steam-microwave solidification method

Mixture sizes of sand-sodium-silicate conglomerates and sodium silicate solute content in them influences on the basic physical and technological indicators of molding and core mixtures structured in steam-microwave environment have been investigated. Sand-sodium-silicate mixture structured by steam-microwave environment (steam-microwave solidification method – SMS-process) composition has been optimized. Standard and generally accepted methods and techniques of molding mixtures investigation have beenused in this study. For mixtures manufacturing have been used: quartz sand brand 1K2O202; sodium silicate solute with silicate modulus of 2.8…3.0 and specific gravity of 1.42…1.44 g/cm3. Quartz sand cladding has been implemented with 0.5 and 2.5% sodium silicate solute (by weight, over 100% sand). Sand-sodium-silicate conglomerates have been scattered in sieves and conglomerates with sizes less than 0.315mm and with sizes from 0.315 to 0.63mm have been used for research. Mixture composition has been optimized according to results of simplex planning and experimental data by simplex triangles constructing and superimposing their formatted images on each other with darkened fields between isolines that do not meet of each parameters required level. To plot simplex lattices, model with simplex lattice plan of incomplete cube in Scheffe’s triple system has been used. For the first time, influence of mixture sand-sodium-silicate conglomerates sizes and sodium-silicate-solute content in them on basic indicators of mold and rod mixtures structured in steam-microwave environment has been established, and their composition has been optimized. Data obtained will be useful in molds and rods structured by SMS-process manufacturing. They will have predictable indicators of properties that correspond to their allowable level. Optimal composition of sand-sodium-silicate mixture, structured by SMS-process, is mixture of quartz sand, part of which passed through sieve with cell of 0.315 mm and have sodium silicate solute content (МSiO2=2.8…3.0, 2=1.42…1.44 g/сm3) in amount of 1.5% (by weight, over 100% quartz sand). Keywords.Sand, silicon silicate solute, steam-microwave solidification, optimization, conglomerates, strength, gas permeability, crushability, density, beam deflection, knockout energy.

Evaluation of the timing covert channel capacity considering packet transfer time distribution

Lampson was the first to introduce a covert channel as a channel that was not designed for information transmission. The problem of information leakage via network covert channels has a large scale due to the facts that IP protocol is widely used and has a lot of features to use it for hidden information transmission. Usually covert channels are divided into two groups by transmission technic: storage and timing covert channels. In the paper authors provide brief survey for network timing and storage covert channels as well as methods of information leakage counteraction. According to best practices, information systems and infrastructure have an information security policy with the requirements about allowable level of covert channel capacity. However, to take a decision about any method activation it is important not to allow underestimation of covert channel capacity. For the effective prevention of information leakage via network covert channels authors suggest a way to assess timing covert channel capacity. Two binary timing channels have been investigated: on/off and channel based on inter packet intervals modulation. In on/off covert channel the sender sends a packet during a preliminarily agreed time interval to transmit the bit «1» and does not send to transmit the bit «0». In a covert channel based on inter packet intervals modulation the sender sends packets with different time intervals defining different bits. The scientific novelty consists in taking into account network load conditions while assessing maximum amount of information that can be stealthily transmitted from secure infrastructure to an illegitimate receiver beyond secure perimeter. Authors investigated cases when packet transfer time from the sender to the receiver in the network (PTT) is defined by normal and exponential distribution – the most common distribution according to current research. Covert channel capacity is evaluated as a function of covert channel parameters and parameters of the PTT distribution (DPTT). Conducted research shows that in case when secure officer does not take into account typical load for the network and DPTT type maximum covert channel capacity will most likely be underestimated. If allowable level of covert channel capacity is set up, obtained results allow to take right decision about activation of countermeasures to prevent information leakage.

THEORETICAL PRINCIPLES OF SAVING GROUNDWATER USE INFOGEOFRAMES IN HYDROGEOLOGY

Theoretical bases of information support of geological prospecting researches and works on use and protection of underground waters are considered. The methodology of information support is based on the principles of target infogeological structuring of the geological environment on the basis of traditional methods of formational analysis taking into account hydrogeological (hydrodynamic and hydrochemical) components. Prospects for the introduction of a system of frame organization of the geological environment in infogeological modeling are discussed. In the applied sense, research focuses on that part of the underground hydrosphere that is now or in the future able to meet the needs of mankind in drinking, mineral, technical, industrial, thermal waters. The principles of management of groundwater resources based on the ratio of renewable natural (dynamic resources, which make up the majority of open hydrodynamic systems in the zone of intensive water exchange), renewable manmade (artificial or disturbed resources) and non-renewable components (capacitive reserves and semi-closed structures). Accordingly, during the operation of deposits, not only the calculated value of the allowable level reduction but also the "allowable balance" of groundwater should be observed. It is also proposed to define and agree on the boundaries of deposits and boundary conditions. The latter should be responsible not only for the water intake production, but also to demonstrate the degree of hydrodynamic, hydrochemical, geological protection and the risk of quantitative and qualitative depletion. Groundwater extraction must be balanced by restoring their reserves, which can be achieved by combined alternate water use of surface and groundwater sources, the creation of infiltration basins and more. On this conceptual basis, a system of information support for research and work on the use and protection of groundwater is proposed, which in the long run should be as close as possible to world standards.

FEA Simulation of the Biomechanical Structure Overload in the University Campus Planting

Research of breakage of the chestnut tree branch on the planting of university campus is provided. Collapse is caused by a severe accidental wind gust. Due to collapse in the student environment, the investigation has additional methodical value for the teaching of FEA simulation. The model includes roots, trunk, branch, and conditional crown, where the trunk-branch junction is steady enough. The load-bearing system of tree is taken as an example of an effective bionic design. The branch has grown with the implementation of the idea of “equal-strength console”—the change of sections along the branch provides constant stress level and near uniform dispensation of their without stress concentrators. Static simulation of the tree loading is provided both in the linear formulation and in the geometrically nonlinear one. It is proved that in the trunk-branch junction area the stresses are twice lower than the branch itself, and it is not the place for fracture. For the given wind pressure, the work stress in the branch has exceeded twice the allowable level under bending with some torsion. In such construction (of the tree), the breakage could happen even in the perfect branch condition due to her severe overloading.

ASSESSMENT OF RADIONUCLIDES IN SOME NIGERIAN MADE CEREALS AND TEA PRODUCTS

This study investigated the presence of the radionuclides 226Ra, 232Th, 40K and 137Cs in some cereals and tea products commonly available in Nigerian markets. Fifteen cereal samples and ten tea samples were purchased from different markets in Lagos, Nigeria. Gamma-ray spectrometric analyses of the samples were done using a High Purity Germanium (HPGe) detector to obtain the activity concentrations of the radionuclides with 137Cs being below the detection limit in all the samples analyzed. The mean activity concentrations (in Bqkg-1) of 226Ra, 232Th and 40K in the cereal samples were (0.839 ± 0.713), (1.153 ± 1.084) and (22.514 ± 8.897) respectively; while the values for the tea samples were (1.145 ± 0.765), (0.94 ± 0.601) and (19.212 ± 9.533) respectively. The associated hazard indices for the cereals ranged from 0.0065 to 0.0368 while that for the tea products varied from 0.0044 to 0.0292. These values are well below the world recommended limit of 1.0. The calculated annual effective doses due to the ingestion of the investigated samples ranged from 0.068 mSvy-1 (for age groups from 1 y) to 0.189 mSvy-1 (for age group 17 y). For the tea samples, the highest value was found in the age group 12 – 17 y, while the lowest was found in the age group 1 – 2 y. These values are below the allowable level of 1 mSv per annum for members of the general public as recommended by the International Commission on Radiological Protection. This indicates that the consumption of these cereals and teas do not pose as health hazards to both children and adults in the populace.

On the method of calculating the cost of sugar beet

In the current economic system of Russia, agricultural production occupies a predominant place as a tool for improving the country’s national security. Agricultural production is characterized by a number of features that are manifested, among other things, in the accounting and analytical activities of economic entities aimed at forming the cost of various types of products, its analysis and subsequent management, which makes it possible to ensure the necessary level of agricultural output at the minimum allowable level of costs. The article presents the results of research on cost accounting and cost calculation on the example of sugar beet products, as well as measures to improve the accounting support of calculation processes in the field of beet farming.

Assessment of Toxic Metals in Some Selected Cosmetic Products in Nigeria and Their Health Risks

The study determined the levels of heavy metals in some selected cosmetic products, commonly marketed in Nigeria, and assessed their possible potential human health risks. The health risk assessment was patterned according to the model of the United States Environmental Protection Agency (USEPA). The heavy metals concentrations ranged from 0.043 0.027 (Pb) - 1.89 1.04 (Fe) with the concentration order: Fe]Cu]Zn]Mn]Cr]Cd]Pb. The total daily intake for all the metals were generally below maximum tolerable daily intake (MTDI). The estimated hazard index, hazard quotient and cancer risks were all within allowable level. The study indicated that users of the studied products are less susceptible to any significant health (carcinogenic or non-carcinogenic) risk.

Analysis of Stoppages in the Process of Roadway Drivage Caused by Exceeding the Maximum Allowable Level of Methane Concentration

Methane is one of the most dangerous gases occurring in mining production. Being inseparably connected with the rock mass, it presents a serious risk to occupational safety and reduces the effectiveness of mining production. A particularly high methane hazard occurs directly during exploitation in longwall headings and the drivage of roadways. Exceeding the maximum allowable level of its concentration in these headings makes it necessary to disconnect all machines until this concentration level is reduced. This leads to unscheduled downtimes of such machines, thus increasing the costs of their operation and decreasing their effectiveness. The paper demonstrates the results from the analysis of machine downtimes in the drivage of roadways, caused by excessive methane concentration levels. The analyses were based on the indications from the system for automatic monitoring of the ventilation parameters in this heading. The results obtained clearly demonstrated that exceeded values of methane concentration caused a series of unexpected downtimes in the drivage process. As a result, the process was disturbed and its effectiveness reduced. The presented analyses are one of the first to address the issue of how methane emissions affect machine downtimes. However, this phenomenon represents a major problem that needs to be addressed comprehensively in order to minimise the losses arising out of the necessary disruptions to the exploitation process.