X-ray fluorescence determination of small quantities of hafnium in nuclear pure zirconium materials

An important chemical impurity in the composition of zirconium materials for nuclear power engineering is hafnium, the content of which should not exceed 0.05 and 0.01% for domestic and foreign alloy grades, respectively. Hafnium, being an analogue of zirconium in its chemical properties, is difficult to be analyzed using classical methods of analytical chemistry. Among the physical methods, the X-ray fluorescence method is the most expressive, which is important in conditions of continuous production. The method of X-ray fluorescence for measuring the content of hafnium in zirconium-containing material has been tested on the example of potassium fluorozirconate, a precursor for obtaining alloys. With various combinations of crystal analyzers, detectors, and collimators of the wave-dispersive spectrometer, the ratios of the intensities of the analytical lines of Hf and Zr in the second order of reflection were refined, and the degree of decrease in the fluorescence intensity of those lines was determined. The X-ray fluorescence spectra of hafnium lines in potassium fluorozirconate at the content characteristic of nuclear-pure zirconium are studied. The possibility of recording the intensity of the Hf analytical lines and methods of eliminating the interference from the Zr lines in the second order of reflection are considered. The metrological characteristics are calculated for Hf analytical lines. It is shown that the smallest error and the lowest detection limit (0.001%) is provided when using the HfLβ1 line at certain settings of the wave-dispersive spectrometer, including the X-ray tube operation mode, a combination of a crystal analyzer, a detector and a collimator, as well as the amplitude discriminator settings. The method of accounting for the background is recommended. The proposed method of hafnium determination is applicable to the materials with a constant content of zirconium.

Effect of Pozzolana and Lime on Expansive Soil Properties

This study investigates the effect of pozzolana and quick lime as stabilizer materials on expansive soil properties. Disturbed soil sample was collected from Al-Qadarif city in east of Sudan. The basic properties, swelling and strength of the soil were measured. The soil shows very weak strength and very high swelling potential. Mineralogical analysis tests were conducted to the soil using XRD tests. The soil contains significant amount of montmorillonite mineral (86%). Laboratory tests were undertaken on soil stabilized with varying percentage of pozzolana only (0, 5, 10, 15, 20, and 30%) and combination of pozzolana with constant content of quick lime (5%). Compaction, California Bearing Ratio (CBR), free swell, swell present and swelling pressure tests were performed on natural and treated soil. The pozzolana was obtained from Jebal Meidob and the lime obtained from local kilns in Kassala. The results showed that the treatment of expansive soil by combination of pozzolana and quick lime reduced soil swelling coupled with significant increase on soil strength. While the use of pozzolana only has marginal effective. It could be concluded that stabilization of expansive soil by pozzolana-lime admixture is successful.

An Experimental Study On Concrete Containing Nano And/Or Micro Silica

The effect of using Portland cement, nano silica (NS) and /or micro silica on the mechanical and physical properties of concretes containing fine aggregate only is investigated. Two groups divided into five series each have been designed and tested. The first group was containing the nano-silica only, while the second group contained different ratios of nano silica and a constant content of 8 % of silica fume (SF) (by weight) as partial replacement of cement. Water cementations ratio (w/c) of all mixtures was constant and equal to 0.22. The cement content in all series was 800 kg/m3. Commercially available nano silica (NS) was used in the mixture for the partial substitution of cement at ratios of 0, 0.5, 1.0, 2 and 3% by weight. It was found that the addition of nano –silica is significantly enhance compressive, tensile and modulus of elasticity of concrete. From the test results obtained it has been noted that the mix containing 2 % possess significantly improved mechanical properties, furthermore, the group samples of concrete containing binary cementations nano-silica and silica fume showed better results than concrete containing nano silica only.

Гидротермальный нанокремнезем в сельскохозяйственном растениеводстве и биотехнологии

Experiments on application of hydrothermal nanosilica to increase productivity agricultural plants were carried out. Nanosilica sol was produced by ultrafiltration membrane concentration of orthosilicic acid polymers of hydrothermal solution to SiO2 content 10–20 mas. %. Plants treatment was done by diluted sol with SiO2 content in the range 0.0001–0.2 mas. %. Treatment of seeds ore upground parts of plants once ore twice was applied. SiO2 consumption was about 10–20 g per hectare. Experiments with wide range of plants was done, including potatoes, cabbage, vegetable marrow, onion, mustard, amaranth, tomato, sugar, wheat, beet and radish. Besides productivity biochemical and biometric parameters were changed: plants height, quantity, length, wide of leafs and others. For example, in upground mass of amaranth was detected decreasing of cellular tissue content and increasing grease, total saccharin content with constant content of carotene and protein. In amaranth seeds increasing of oil, squalene, starch, protein, vitamin C content was detected.

Scientifically based production criteria for chocolate semi-finished products using fruit and vegetable powders

Chocolate glaze consists mainly of sugar (50%) and fat (35%) and is a high-calorie semi-finished product with a high content of simple carbohydrates. The standard for glaze provides the possibility of producing chocolate glaze with fruit and vegetable components, which reduces the content of simple carbohydrates. Studied and justified the criteria for the production of chocolate glazes with different contents of fruit and vegetable powders. Analysis of the rheological parameters of chocolate semi-finished products showed that the introduction of fruit and vegetable powder instead of part of the sugar leads to a significant change in the nature of the rheological behavior of the semi-finished product. The yield strength increases from 3.4 to 12.6 Pa as the proportion of fruit and vegetable powder in the formulation increases. In order to determine the effect of the production method on changes in the yield strength of fruit and vegetable chocolate glaze, a series of experiments was carried out. It was found that with a constant content of fruit and vegetable powder (11%), temperature, processing time and machine support, the resulting chocolate glazes differed in their rheological characteristics. It was found that the greatest reduction in the yield strength of fruit and vegetable chocolate glazes during the production process can be achieved by stage-by-stage grinding of the formulation components in a ball mill and the additional introduction of PGPR emulsifier at the conching stage. The quality of chocolate semi-finished products depends not only on rheological parameters, but also on crystallization properties. The developed chocolate glazes with different contents of the fruit and vegetable component were processed at a temperature of about 30 °C in a laboratory tempering machine in order to form and stabilize fat crystals in ?-form. Then, the temperindex was determined. It was found that, subject to the same tempering conditions, with an increase in the proportion of fruit and vegetable powder, the temperature of glazes increases. Glazes with a mass fraction of fruit and vegetable powder of more than 7% were distinguished by the properties of re-tempered semi-finished products - the presence of large fat crystals, a rough structure and the absence of surface gloss. In order to obtain the optimal temperature index of glazes with a content of fruit and vegetable raw materials of more than 7%, their tempering modes were developed.

Sorption materials on the basis of technical cellulose from straw and rice husk

Целлюлоза из плодовых оболочек злаковых культур обладает высокой сорбционной емкостью. Однако относительно короткие волокна затрудняют получение прочного бумажного материала. В то же время целлюлоза из соломы, наоборот, обладает относительно большой длиной волокна и приемлемыми сорбционными свойствами. Для разработки эффективных целлюлозосодержащих сорбентов интерес представляет композиционный материал из целлюлозы шелухи и целлюлозы соломы. Цель исследования – получение сорбционного материала на основе технической целлюлозы из соломы и шелухи риса. Техническая целлюлоза из соломы и шелухи риса получена окислительно-органосольвентным способом с предварительной щелочной обработкой растительного сырья (зольность ее 0,05 % от абсолютно сухой целлюлозы). При этом целлюлозу из соломы риса применяли в качестве целлюлозы-основы, а целлюлозу из шелухи риса – как целлюлозу- адсорбент. При постоянном содержании целлюлозы-основы в композиции независимо от степени ее помола капиллярная впитываемость изменяется в пределах погрешности измерений. При постоянном содержании целлюлозы- основы в композиции и добавлении к ней целлюлозы-адсорбента с возрастающей степенью помола капиллярная впитываемость снижается незначительно (на 1…2,5 мм). Сорбционная способность по йоду зависит от степени помола как целлюлозы-адсорбента, так и целлюлозы-основы. С увеличением степени помола сорбционная способность по йоду возрастает. Адсорбционная способность по метиленовому голубому при постоянном содержании 50% целлюлозы-основы в композиции и добавлении к ней целлюлозы-адсорбента с увеличивающейся степенью помола (35, 39, 43,5, 47,5 оШР) возрастает. Установлено, что количественная оценка эффективности композиции подтвердила наличие эффекта синергизма, который характерен для адсорбционной способности по метиленовому голубому и возрастает с увеличением степени помола целлюлозы- адсорбента с 1,07 до 1,12 с учетом погрешности эксперимента. Cellulose from the fruit shells of cereals has a high sorption capacity. However, relatively short fibers make it difficult to obtain durable paper material. At the same time, straw cellulose, on the contrary, has a relatively long fiber length and acceptable sorption properties. For the development of effective cellulose sorbents of interest is a composite material of cellulose husks and cellulose straw. The aim of the work is to obtain sorption materials on the basis of technical cellulose from straw and rice husks obtained by oxidation-organosolvent method with pre-alkaline treatment of vegetable raw materials. In the course of work, technical cellulose from straw and rice husks with ash content of 0.05% of completely dry cellulose was obtained. Upon receipt of the sorption material, cellulose from rice straw is used as a base cellulose, and cellulose from rice husk as cellulose is an adsorbent. With a constant content of cellulose base in the composition, regardless of its degree of grinding, capillary absorbency varies within the measurement error. With a constant content of cellulose-base in the composition and the addition of cellulose-adsorbent with an increasing degree of grinding capillary absorbency decreases slightly (1...2,5 mm). The sorption capacity of iodine depends on the degree of grinding, as cellulose-adsorbent, and the degree of grinding of cellulose-base. With increasing degree of grinding sorption capacity of iodine increases. Adsorption capacity of methylene blue at a constant content of cellulose-base 50 % in the composition and the addition of cellulose- adsorbent with an increasing degree of grinding (35, 39, 43.5, 47.5 0SHR) increases. It was found that the quantitative evaluation of the composition efficiency confirmed the presence of synergism effect, which is typical for the adsorption capacity of methylene blue and increases with increasing the degree of cellulose-adsorbent grinding from 1.07 to 1.12, taking into account the experimental error.

Concrete propensity to fire spalling: testing and observations

This article presents results of fire spalling tests on small concrete slabs and studies of material parameters that may increase its occurrence. Experimental techniques enabling to study and determination of material features are presented and discussed. Experimental studies on spalling behaviour of elements were carried out on seven different concrete mixes with constant content of cement paste and mortar. Research aimed at determining influence of the following parameters: w/c ratio (0.30; 0.45; 0.60), cement type (CEM I, CEM III) and type of aggregates (riverbed gravel, granite, basalt) on fire concrete spalling. Paper discusses also the influence of cold rim that forms while testing slab-like element is subjected to one-side heating.

CALIBRAÇÃO DE UM SENSOR CAPACITIVO PARA ESTIMATIVA DA UMIDADE EM TRÊS CLASSES DE SOLOS

CALIBRAÇÃO DE UM SENSOR CAPACITIVO PARA ESTIMATIVA DA UMIDADE EM TRÊS CLASSES DE SOLOS SAMUEL COLA PIZETTA1; ROGÉRIO RANGEL RODRIGUES2; GERALDO MAGELA PEREIRA3; FABIÁN ENRIQUE DÍAZ PACHECO4, MARCELO RIBEIRO VIOLA5 E LUIZ ANTÔNIO LIMA6 1Doutorando em Recursos Hídricos em Sistemas Agrícolas pela Universidade Federal de Lavras (UFLA)- Campus Universitário, Departamento de Engenharia, C.P. 3037- CEP 37200-000, Lavras-MG, Brasil. [email protected];2 Doutor em Recursos Hídricos em Sistemas Agrícolas pela Universidade Federal de Lavras (UFLA)- Campus Universitário, Departamento de Engenharia, C.P. 3037- CEP 37200-000, Lavras-MG, Brasil., técnico no IFMA, Campus Santarém, Brasil. [email protected];3 Professor Titular da Universidade Federal de Lavras (UFLA) - Campus Universitário, Departamento de Engenharia, C.P. 3037- CEP 37200-000, Lavras-MG, Brasil. [email protected];4 4 Engenheiro Agrícola pela Universidad de Sucre (Unisucre)- Calle 25 # 39-61, Las Margaritas, Sincelejo-Sucre. Colômbia. fabian_18 hotmail.com;5 Professor Adjunto da Universidade Federal de Lavras (UFLA) – Cam pus Universitário, Departamento de Engenharia, C.P. 3037- CEP 37200-000, Lavras-MG, Brasil.. [email protected];6 Professor Associado da Universidade Federal de Lavras (UFLA) - Campus Universitário, Departamento de Engenharia, C.P. 3037- CEP 37200-000, Lavras-MG, Brasil.. [email protected] 1 RESUMO Um dos maiores desafios de domínio agrícola atualmente é a mensuração prática, rápida e precisa do teor de água no solo. Dessa forma, o conhecimento acerca dos equipamentos que estimem essa umidade é de fundamental importância. Nesse contexto, objetivou-se com este estudo, efetuar a calibração dos sensores de capacitância Eletrodex por meio do método padrão de estufa em três classes de solo, sendo o Argissolo, Latossolo e Nitossolo. Os solos foram coletados no Campus da Universidade Federal de Lavras (UFLA) e o experimento foi realizado no Laboratório de Hidráulica, no município de Lavras, estado de Minas Gerais. Para a calibração foram utilizados sete níveis de umidade que compreenderam diferentes valores de porcentagens da disponibilidade total de água no solo (DTA). Os resultados demonstraram que a utilização desse sensor não permitiu estimar, de forma satisfatória, a umidade volumétrica do solo, nos intervalos de umidade testados, em nenhum dos solos submetidos à calibração, uma vez que não foi possível obter equações que apresentassem coeficientes de determinação adequados. Palavras-chave: instrumentação, constante dielétrica, teor de água, sensor FDR. PIZETTA, S. C.; RODRIGUES, R. R.; PEREIRA, G. M. PACHECO, F. E. D; VIOLA, M. R.; LIMA, L. A.CALIBRATION OF A CAPACITANCE SENSOR FOR MOISTURE ESTIMATION IN THREE SOIL CLASSES 2 ABSTRACT One of the largest agricultural challenges has been the practical, quick and precise measurement of water content at soils, thus requiring satisfactory equipment to perform such task. This research investigated capacitive soil moisture sensors defined by the manufacturer as Eletrodex, comparing its measurements to dry oven techniques for soil moisture determination at three soil classes: Argisol, Oxisol, and Nitosol. Soils were collected at the Campus of the Federal University of Lavras (UFLA), and the experiment was carried out at the Hydraulics Laboratory in Lavras, state of Minas Gerais. For calibration, seven moisture levels were used, which comprised different percentages of total available moisture (TAM). Results lead to the conclusion that the sensor does not satisfactorily estimate the volumetric water content for any soil class tested. Such conclusion is based on the fact that no adequate coefficients of determination could be obtained at calibration curves. Keywords: instrumentation, dielectric constant, content of water, FDR sensor.

Surface Tension in a Cu-Pb-Fe Liquid Alloy (XCu=0.9)/Al2O3/Gaseous Phase System

The surface tension of the liquid ternary Cu-Pb-Fe alloys at the constant content of copper (XCu=0.9)-refractory material Al2O3-gaseous phase was determined. The experiments were performed in the range of temperature between 1100 and 1350 °C at the different content of lead and iron (XFe/XPb+XFe). The surface tension was determined by sessile drop method. The composition of the investigated alloys corresponds to the composition of the Cu-Pb-Fe alloys obtained via the reduction of the slag obtained during the direct-to-blister flash smelting process in an electric furnace. Images of the liquid drops were made using the X-ray technique and the surface tension values were calculated using the corresponding software programs.

Changes in alfalfa cell wall structure during vegetation

The investigation was done on 141 samples of one alfalfa cultivar, collected from the same location during the first three growth cycles: spring growth, the first and the second regrowth. Within each growth cycle, sampling was done during the whole growing period, commencing when plant height was below 150 mm and continuing until plants were bearing ripe seeds. On all collected samples the following cell wall characteristics were determined: neutral detergent fibre (NDF), acid detergent fibre (ADF), acid detergent lignin (ADL), neutral detergent insoluble crude protein (NDICP), acid detergent insoluble crude protein (ADICP). Cellulose and hemicellulose were detected on the base of the mentioned chemical parameters. Significantly lower (p<0.01) content of aNDF, ADF, ADL, ADICP and cellulose is found in the second regrowth, while there were no significant differences between the other two growth cycles. Except in NDICP and ADICP, the increase in all accompanying components of the cell wall was observed, and expressed in average daily changes. There was no consistent trend in NDICP and ADICP. During the spring growth from late bud to full-bloom stage the ?plateau? was observed. The plateau was represented as almost constant content of aNDF, ADF, ADL and cellulose. The correlations between all components of the cell wall were shown. The equation aNDF = 36.713 + 1.181 ? ADF is recommended for conversion of ADF into aNDF in alfalfa.