scholarly journals INFLUENCE OF MECHANOMAGNETIC ACTIVATION OF SOLUTIONS CaCl2 AND Na2S2O3 ON PHASE STRUCTURE OF CEMENT STONE

2019 ◽  
Vol 62 (12) ◽  
pp. 101-107
Author(s):  
Tatyana E. Slizneva ◽  
Marina V. Akulova ◽  
Pavel B. Razgovorov
Keyword(s):  
Solid Phase ◽  
Tap Water ◽  
Pore Space ◽  
Control Sample ◽  
Hydrodynamic Cavitation ◽  
Cement Stone ◽  
Cement Pastes ◽  
Carbonate Ion ◽  
Joint Influence ◽  
Reactive Oxygen Forms

The mechanism of the joint influence of the magnetic field and hydrodynamic cavitation on the properties of CaCl2 and Na2S2O3 solutions used for mixing cement pastes is considered. Hydrodynamic cavitation leads to the formation of reactive oxygen forms, HCO3– anions, carbon dioxide nanobubbles, and initiates the interaction of new forms with impurity metal cations dissolved in water. After mechanomagnetic treatment of the solutions, particles of a solid phase with sizes of 5...10 and 10...100 nm were found in them. The observed increase in the ξ- potential indicates the stabilization of such dispersed systems with the preservation of nanoscale fractions in them (up to 3 days). At the same time, the progress of reactions under the conditions of tightness that occur after cement paste has been mixed. The effect of activating factors in tap water is more pronounced than in distilled water, which is explained by the process of hydration of the carbonate ion and the formation of fine nucleation centers. Using X-ray phase analysis, it was found that, along with calcite, aragonite crystallizes in the resulting cement stone, which is practically absent in the control sample. In addition, the analysis of diffraction patterns taken on the modified samples reveals the inclusion of a carbonate ion. Obviously, optimization of the pore space in the cement stone is achieved both by clogging the pores with fine calcium carbonate, and by forming small pores during crystallization of ettringite-like phases. It is established that the resulting cement stone is characterized by increased strength (by 9-30%) and frost resistance (up to 55%) compared to that obtained by the traditional method.

scholarly journals PROCESSES OF CARBONIZING SHRINKAGE OF CONSTRUCTION MATERIALS

2019 ◽  
pp. 178-194
Author(s):  
V. K. Kozlova ◽  
V. A. Lotov ◽  
Yu. S. Sarkisov ◽  
V. V. Logvinenko ◽  
I. A. Rakhmanova ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Cement Paste ◽  
Calcium Silicate ◽  
Building Materials ◽  
Solid Phase ◽  
Pore Space ◽  
Construction Materials ◽  
Cement Stone ◽  
Hydration Products ◽  
Wall Structures

Relevance: This paper studies the durability of structures made of various building materials and the effect of carbon dioxide on building materials with a view to reduce its aggressive and destructive effects. Purpose: The aim of the paper is to identify and eliminate the causes of the building material destruction during their carbonization. Materials/Methods: Silicate brick, cement stone and concrete. Research findings: Research is carried out into the destruction of wall structures made of calcium silicate brick and carbon dioxide corrosion of hydration products in calcium silicate brick and cement brick in concrete. It is found that carbonization in hydration products results in their transfer to a denser state which is accompanied by the reduction in the volume of shrinking deformations which cause sometimes the breach and fracture of material. When considering the water/cement system, it is shown that more credible and visible results on shrinkage processes can be obtained through parameters of its volume phase composition which allow controlling the parameters of the structure rearrangement from the initial to final states of the system, i.e. from cement paste to cement brick hardened at different time intervals. It is shown that after 28 days of hardening, the degree of filling the initial pore space with hydration products reaches 67%, while the porosity of cement brick in the final state is 16.5% at the initial composition of the solid phase Fs1 = 0.5; 13.5% at Fs1 = 0.55; 12.8% at Fs1 = 0.6; 11.2% at Fs1 = 0.65 and 0.7-9.0% at Fs1 = 0.7. It follows that shrinkage processes intensify in cement paste with the initial porosity over 40-50 %. It is possible to reduce the negative effect from shrinkage processes via the addition of carbonate-containing mineral additives such as lime rock or dolomite to the cement or lime and sand composition.

Influence of Polyepoxysuccinic Acid on Solid Phase Products in Portland Cement Pastes

2018 ◽  
Vol 33 (5) ◽  
pp. 1140-1149 ◽  
Author(s):  
Chenguang Hu ◽  
Xiaoyan Wang ◽  
Ruiying Bai ◽  
Gang Liu ◽  
Xiaoxin Feng ◽  
...  
Keyword(s):  
Portland Cement ◽  
Solid Phase ◽  
Cement Pastes

scholarly journals Effect of Addition of Citric Acid and Sodium Benzoate on pH and Microbial Profile of Soymilk

2020 ◽  
pp. 21-31 ◽  
Author(s):  
Johnpaul I. Agbaka ◽  
Charles N. Ishiwu ◽  
Ajibola N. Ibrahim
Keyword(s):  
Citric Acid ◽  
Sodium Benzoate ◽  
Food Systems ◽  
Tap Water ◽  
Control Sample ◽  
Storage Period ◽  
Ambient Conditions ◽  
Alternative Source ◽  
Microbial Profile ◽  
Chemical Preservatives

Aim: To study the synergistic effect of chemical preservatives on the keeping quality of soymilk. Study Design: Ten soymilk samples were prepared and treated with different concentrations of citric acid and sodium benzoate and stored at ambient conditions. Place and duration of Study: The present study was conducted at the Department of Food Science and Technology, Nnamdi Azikiwe University, Awka between March 2015 and June 2016 Methodology: Ten (10) soymilk samples were prepared. Soybean seeds (2 kg) that are free of dirt and stones were weighed and steeped in 4 L of tap water, a 12 h steeping regime was adopted. Each soymilk sample was formulated by adding different concentrations of sodium benzoate and citric acid, while the control sample had no treatment. All soymilk samples were then boiled at 75oC for 15 minutes and stored in storage bottles. Standard microbiological techniques were employed in the isolation and enumeration of potential spoilage organisms in soymilk samples. pH analysis was conducted throughout the storage period. Results: There was a decrease in pH of all soymilk samples with increasing storage time. pH at day 0 ranged between 6.2 to 7.2. Isolated bacteria in 10 soymilk samples included Streptococcus sp., Pseudomonas sp., Proteus sp., Bacillus spp., Staphylococcus aureus, Klebsiella sp., Escherichia coli, and Enterobacter species. However, results obtained showed that soymilk could keep up to 7 days at ambient temperature, encouraging the use of citric acid and sodium benzoate as chemical preservatives. Conclusion: In the present study, preservation of soymilk samples from a combination of citric acid and sodium benzoate which are chemical preservatives was found to be more effective than several organic preservatives. Hence, they represent an alternative source of chemical antimicrobial substances for use in food systems to prevent the growth of food borne microorganisms and extend the shelf-life of processed food.

scholarly journals Effect of adding essential oils of caraway and rosemary on volatile aroma compounds derived from stored vacuum packaged minced turkey meat

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Magdalena Michalczyk ◽  
Paweł Satora ◽  
Joanna Banaś ◽  
Grzegorz Fiutak
Keyword(s):  
Beneficial Effect ◽  
Essential Oils ◽  
Solid Phase ◽  
Control Sample ◽  
Acid Value ◽  
Fat Oxidation ◽  
Viable Count ◽  
Gas Chromatography Mass Spectrometry ◽  
Total Viable Count ◽  
Turkey Meat

AbstractChanges in the odor of meat during its storage are one of the basic indicators affecting its assessment and possible disqualification. The aim of the study was to determine whether the addition of essential oils may affect the composition and concentration of volatile compounds included in the aroma of stored turkey meat. We investigated the effect of adding essential oil (EO) of caraway (0.02% v/w), rosemary (0.02% v/w) and a mixture of the two (0.01% each) on the composition of volatile compound fractions formed during 10-day storage of vacuum-packed minced turkey meat. The EOs used were also evaluated for their influence on microbial contamination (total viable count and lactic acid bacteria count), sensory quality (odor and taste) and the level of fat oxidation (acid value, peroxide value and p-anisidine value) and pH in chill-stored samples. In terms of sensory indicators, the greatest beneficial effect of adding oils was noted in the odor of raw meat. Use of the HS-SPME/GC-MS (headspace-solid phase microextraction/gas chromatography-mass spectrometry) method showed that the addition of oils significantly reduced the amounts of benzeneacetaldehyde, 2-octenal and ethyl 2-methyloctanoate compared with the control sample. In addition, in the presence of essential oils of rosemary and caraway, decreases were noted in benzaldehyde and 9-octadecenal, respectively. These changes may potentially affect the reception of the odor. There was a beneficial effect of the oils in reducing the levels of fat oxidation indicators, including peroxide. However, the oils at applied concentrations had no significant effect on the total viable count and LAB count.

scholarly journals Investigation of the structure of cement conglomerates

2021 ◽  
Vol 266 ◽  
pp. 03005
Author(s):  
D. N. Shabanov ◽  
E. Trambitsky ◽  
E. Borovkova
Keyword(s):  
Strain State ◽  
Residual Life ◽  
Experimental Studies ◽  
Cement Stone ◽  
Virtual Model ◽  
Structural Studies ◽  
Acoustic Sensors ◽  
Cement Pastes ◽  
The Moment ◽  
Physical And Chemical

This article describes the structural studies of a cement conglomerate, its evolution from the moment of formation to the loss of operational properties. Physical and chemical phenomena and interactions of various elements of cement stone are considered. The study of its rheology includes creating a virtual model and monitoring the formation of the structure of cement pastes by acoustic emission (AE). The results of combined experimental studies to determine the residual life of cement stone samples using AE and tensometry methods are presented. The authors created a complex for monitoring the stress-strain state of artificial conglomerates, which includes both internal and acoustic sensors.

Obvious and less obvious processes of aggregate formation in soil

2021 ◽  
Author(s):  
Hans-Jörg Vogel ◽  
Mar­ia Balseiro-Romero ◽  
Philippe C. Baveye ◽  
Alexandra Kravchenko ◽  
Wilfred Otten ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Structure ◽  
Solid Phase ◽  
Pore Space ◽  
Imaging Techniques ◽  
Mineral Soil ◽  
Aggregate Formation ◽  
Conceptual Approach ◽  
Soil Matrix ◽  
Biophysical Processes

<p>Soil structure, lately referred to as the ''architecture'' is a key to explain and understand all soil functions. The development of sophisticated imaging techniques over the last decades has led to significant progress in the description of this architecture and in particular of the geometry of the hierarchically-branched pore space in which transport of water, gases, solutes and particles occurs and where myriads of organisms live. Moreover, there are sophisticated tools available today to also visualize the spatial structure of the solid phase including mineral grains and organic matter. Hence, we do have access to virtually all components of soil architecture.</p><p>Unfortunately, it has so far proven very challenging to study the dynamics of soil architecture over time, which is of critical importance for soil as habitat and the turnover of organic matter. Several largely conflicting theories have been proposed to account for this dynamics, especially the formation of aggregates. We review these theories, and we propose a conceptual approach to reconcile them based on a consistent interpretation of experimental observations and by integrating known physical and biogeochemical processes. A key conclusion is that rather than concentrating on aggregate formation in the sense of how particles and organic matter reorganize to form aggregates as distinct functional units we should focus on biophysical processes that produce a porous, heterogeneous organo-mineral soil matrix that breaks into fragments of different size and stability when exposed to mechanical stress.  The unified vision we propose for soil architecture and the mechanisms that determine its temporal evolution, should pave the way towards a better understanding of soil processes and functions.</p>

Synthesis of magnetic metal–organic framework composites, Fe3O4-NH2@MOF-235, for the magnetic solid-phase extraction of benzoylurea insecticides from honey, fruit juice and tap water samples

2019 ◽  
Vol 43 (32) ◽  
pp. 12563-12569 ◽  
Author(s):  
Huixiao Duo ◽  
Xiaofeng Lu ◽  
Shuai Wang ◽  
Licheng Wang ◽  
Yong Guo ◽  
...  
Keyword(s):  
Fruit Juice ◽  
Solid Phase ◽  
Tap Water ◽  
Metal Organic Framework ◽  
Magnetic Solid Phase Extraction ◽  
Magnetic Metal ◽  
Metal Organic ◽  
Magnetic Solid ◽  
Benzoylurea Insecticides ◽  
Organic Framework

Herein, a novel, fusiform-like magnetic metal–organic framework material (Fe3O4-NH2@MOF-235) was fabricated by a facile two-step solvothermal approach.

scholarly journals Preparative Method for Isolating α-Zearalenol and Zearalenone Using Extracting Disk

1999 ◽  
Vol 82 (1) ◽  
pp. 90-94 ◽  
Author(s):  
George M Ware ◽  
Yuhong Zhao ◽  
Shia S Kuan ◽  
Allen S Carman
Keyword(s):  
Limit Of Detection ◽  
Solid Phase ◽  
Control Sample ◽  
Preparative Method ◽  
Reversed Phase ◽  
Fluorescence Detector ◽  
Coefficients Of Variation ◽  
Limit Of Quantitation ◽  
Standard Calibration ◽  
Liquid Chromatographic

Abstract A liquid chromatographic method is described for the determination of zearalenol and zearalenone in corn. Zearalenol and zearalenone are extracted from corn with methanol–water (1+1) and cleaned up using a solid-phase extraction (SPE) disk, separatedon a reversed-phase analytical column, and detected with a fluorescence detector. The SPE disk concentrated and cleanly separated zearalenol and zearalenone from sample interferences. Standard calibration curves for zearalenol and zearalenone for the concentration range 25–500 ng/mL were linear. The small extract disk had a column capacity equivalent to 1 g extracted corn. Zearalenol and zearalenone were added at levels ranging from 10 to 2000 ng/g to a control sample that contained no detectable levels of zearalenol and zearalenone. Both toxins were recovered from spiked samples at 106.3 and 103.8%, with coefficients of variation of 7.6 and 13.0%, respectively. The method has an estimated reliable limit of detection and limit of quantitation around 10 and 40 ng/g for each toxin, respectively.

scholarly journals Determination of N-Nitrosamines by Gas Chromatography Coupled to Quadrupole–Time-of-Flight Mass Spectrometry in Water Samples

Separations ◽  
2020 ◽  
Vol 7 (1) ◽  
pp. 3 ◽  
Author(s):  
Benigno José Sieira ◽  
Inmaculada Carpinteiro ◽  
Rosario Rodil ◽  
José Benito Quintana ◽  
Rafael Cela
Keyword(s):  
Mass Spectrometry ◽  
Environmental Protection Agency ◽  
Ion Trap ◽  
Solid Phase ◽  
Classical Method ◽  
Tap Water ◽  
Time Of Flight ◽  
The United States ◽  
Mass Analyzer

An analytical method based on high-resolution quadrupole–time-of-flight (QToF) mass spectrometry has been developed as an alternative to the classical method, using a low-resolution ion trap (IT) analyzer to reduce interferences in N-nitrosamines determination. Extraction of the targeted compounds was performed by solid-phase extraction (SPE) following the United States Environmental Protection Agency (USEPA) -521 method. First, both electron impact (EI) and positive chemical ionization (PCI) using methane as ionization gas were compared, along with IT and QToF detection. Then, parameters such as limits of detection (LOD) and quantification (LOQ), linearity, and repeatability were assessed. The results showed that the QToF mass analyzer combined with PCI was the best system for the determination of the N-nitrosamines, with instrumental LOD and LOQ in the ranges of 0.2–4 and 0.6–11 ng mL−1, respectively, which translated into method LOD and LOQ in the ranges of 0.2–1.3 and 0.6–3.9 ng L−1, respectively. The analysis of real samples showed the presence of 6 of the N-nitrosamines in influent, effluent, and tap water. N-nitrosodimethylamine (NDMA) was quantified in all the analyzed samples at concentrations between 1 and 27 ng L−1. Moreover, four additional nitrosamines were found in tap and wastewater samples.

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