scholarly journals STRUCTURAL PARAMETERS OF CONCRETE CORROSION RESISTANCE

2021 ◽  
Vol XXVIII (4) ◽  
pp. 133-143
Author(s):  
Albina Eletchih ◽  
Keyword(s):  
Corrosion Resistance ◽  
Organic Acids ◽  
Malic Acid ◽  
Structural Parameters ◽  
Structural Parameter ◽  
Cement Stone ◽  
Fruit And Vegetable ◽  
Chemical Corrosion ◽  
Concrete Corrosion ◽  
Soluble Calcium

This article describes the problem of corrosion of concrete at the enterprises of the wine and fruit and vegetable industry in Moldova, the kind of organic acids that destroy concrete are considered. Such a specific type of chemical corrosion as leaching is also considered. The reaction of the influence of malic acid on concrete is reflected, as a result of which readily soluble calcium malic acid is formed. The structural parameter of corrosion resistance to chemical corrosion has been studied. The formula for the corrosion resistance of concrete is derived and explained. The structural parameter of resistance to chemical corrosion is investigated on various types of concrete. The formula for coefficient resistance of concrete to chemical corrosion is derived. Also, two dependencies are displayed: Dependence of the coefficient of resistance of concrete to chemical corrosion on the volume of cement stone; Dependence of the coefficient of concrete resistance to leaching corrosion on the structural parameter.

scholarly journals Alkali activated cements mix design for concretes application in high corrosive conditions

2018 ◽  
Vol 230 ◽  
pp. 03007 ◽  
Author(s):  
Oleksandr Kovalchuk ◽  
Valentina Grabovchak ◽  
Yaroslav Govdun
Keyword(s):  
Corrosion Resistance ◽  
Phase Composition ◽  
Mix Design ◽  
Cement Stone ◽  
Hydration Products ◽  
Alkali Content ◽  
High Corrosion Resistance ◽  
Corrosion Resistant ◽  
High Corrosion ◽  
Alkali Activated

This paper covers the results of development of corrosion resistant ash alkali-activated cements based on regulation of phase composition of the hydration products through changing the alkali content, content of calciumcontaining cement constituents resulting in the increase strength and density of the cement stone. The results of study suggested to conclude that the cement compositions with predominance in the hydration products of weakly soluble low basic hydrosilicates of calcium, hydrogarnets and minerals similar to natural hydroaluminates exhibited the highest corrosion resistance. The results of comparison suggested to draw a conclusion that the alkali-activated cements Types APC III-400 and ACC V-400, according to National Ukrainian Standard DSTU B V.2.7, had high corrosion resistance compared to that of OPC, thus allowing to recommend the developed cements for the concretes intended for use in aggressive environments, inclusive of sodium and magnesium sulphates and others. Coefficients of corrosion resistance of concretes are higher than 1 after even 42 months.

scholarly journals Wavelet multi-resolution approximation of time-varying frame structure

2018 ◽  
Vol 10 (8) ◽  
pp. 168781401879559 ◽  
Author(s):  
Min Xiang ◽  
Feng Xiong ◽  
Yuanfeng Shi ◽  
Kaoshan Dai ◽  
Zhibin Ding
Keyword(s):  
Parameter Estimation ◽  
Degrees Of Freedom ◽  
Structural Parameters ◽  
Identification Problem ◽  
Frame Structure ◽  
Structural Parameter ◽  
Time Varying ◽  
Engineering Structures ◽  
Time Frequency ◽  
Non Parametric

Engineering structures usually exhibit time-varying behavior when subjected to strong excitation or due to material deterioration. This behavior is one of the key properties affecting the structural performance. Hence, reasonable description and timely tracking of time-varying characteristics of engineering structures are necessary for their safety assessment and life-cycle management. Due to its powerful ability of approximating functions in the time–frequency domain, wavelet multi-resolution approximation has been widely applied in the field of parameter estimation. Considering that the damage levels of beams and columns are usually different, identification of time-varying structural parameters of frame structure under seismic excitation using wavelet multi-resolution approximation is studied in this article. A time-varying dynamical model including both the translational and rotational degrees of freedom is established so as to estimate the stiffness coefficients of beams and columns separately. By decomposing each time-varying structural parameter using one wavelet multi-resolution approximation, the time-varying parametric identification problem is transformed into a time-invariant non-parametric one. In solving the high number of regressors in the non-parametric regression program, the modified orthogonal forward regression algorithm is proposed for significant term selection and parameter estimation. This work is demonstrated through numerical examples which consider both gradual variation and abrupt changes in the structural parameters.

scholarly journals The Cardioprotective Effects of Citric Acid and L-Malic Acid on Myocardial Ischemia/Reperfusion Injury

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Xilan Tang ◽  
Jianxun Liu ◽  
Wei Dong ◽  
Peng Li ◽  
Lei Li ◽  
...  
Keyword(s):  
Citric Acid ◽  
Myocardial Ischemia ◽  
Organic Acids ◽  
Reperfusion Injury ◽  
Malic Acid ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Protective Effects ◽  
Myocardial Ischemia Reperfusion Injury ◽  
Myocardial Ischemia Reperfusion

Organic acids in Chinese herbs, the long-neglected components, have been reported to possess antioxidant, anti-inflammatory, and antiplatelet aggregation activities; thus they may have potentially protective effect on ischemic heart disease. Therefore, this study aims to investigate the protective effects of two organic acids, that is, citric acid and L-malic acid, which are the main components ofFructus Choerospondiatis, on myocardial ischemia/reperfusion injury and the underlying mechanisms. Inin vivorat model of myocardial ischemia/reperfusion injury, we found that treatments with citric acid and L-malic acid significantly reduced myocardial infarct size, serum levels of TNF-α, and platelet aggregation.In vitroexperiments revealed that both citric acid and L-malic acid significantly reduced LDH release, decreased apoptotic rate, downregulated the expression of cleaved caspase-3, and upregulated the expression of phosphorylated Akt in primary neonatal rat cardiomyocytes subjected to hypoxia/reoxygenation injury. These results suggest that both citric acid and L-malic acid have protective effects on myocardial ischemia/reperfusion injury; the underlying mechanism may be related to their anti-inflammatory, antiplatelet aggregation and direct cardiomyocyte protective effects. These results also demonstrate that organic acids, besides flavonoids, may also be the major active ingredient ofFructus Choerospondiatisresponsible for its cardioprotective effects and should be attached great importance in the therapy of ischemic heart disease.

Effect of Vanadium Addition to Aluminum and Aluminum Grain Refined by Titanium on their Chemical Corrosion Rate in Acidic Solution, HCL, at Different Temperatures

2012 ◽  
Vol 510-511 ◽  
pp. 481-486
Author(s):  
A.I.O. Zaid ◽  
G.T.A. Allawi ◽  
A. Al-Haj-Ali
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Rate ◽  
Acidic Solution ◽  
Chemical Corrosion ◽  
Different Temperatures

The paper presents the effect of vanadium addition to aluminum and aluminum grain refined by titanium on the micron level, in the range from 0.005 wt % to 0.236 wt %, on their corrosion resistance in acidic solution, HCl, at three different temperatures namely: 25 °C, 40 °C and 60 °C. It was found that the corrosion rate was slightly increased by the addition of any percentage of vanadium at 25 °C. Furthermore, it was found that the corrosion rate increased with the increase of temperature at any percentage of vanadium addition in the case of both aluminum and aluminum grain refined by titanium. However it was found that addition of vanadium at any percentage to either aluminum or aluminum+ titanium, resulted in decrease of the corrosion rate i.e. improvement in their corrosion resistance in acidic solution at 40 °C and 60 °C. The maximum achieved reduction in corrosion rate was 77 % at 40 °C and 0.148 wt % vanadium addition.

Studies of molecular structure parameters of 20-piperidin-2-yl-5α-pregnan-3β,20-diol and its N-methyl derivative: two inhibitors of Δ24(25) sterol methyl transferase and Δ24(24′) sterol methyl reductase of Trypanosoma cruzi

2001 ◽  
Vol 57 (5) ◽  
pp. 714-721 ◽  
Author(s):  
Reinaldo Atencio ◽  
Gonzalo Visbal ◽  
Sara Pekerar ◽  
Jham Papale ◽  
Julio A. Urbina
Keyword(s):  
Trypanosoma Cruzi ◽  
Structural Parameters ◽  
Spectroscopic Characterization ◽  
Structural Parameter ◽  
Torsion Angles ◽  
Methyl Transferase ◽  
X Ray ◽  
The Family ◽  
Fused Ring ◽  
The Mean

Molecular structural parameters of two potential drugs against Trypanosoma cruzi epimastigotes, 20-piperidin-2-yl-5α-pregnan-3β,20-diol (1) and 20-N-methylpiperidin-2-yl-5α-pregnan-3β, 20-diol (2) were studied using a combination of a stereoselective synthetic route, spectroscopic characterization and single-crystal X-ray analysis. Both compounds were synthesized with an R configuration at C20. This chirality is a consequence of the stereoselectivity observed during the formation of the intermediate 20-pyridin-2-yl-5α-pregnan-3β,20R-diol (4). NMR data indicated that the six-membered aza ring of (2) is conformationally more restrained, in CDCl3 solution, than (1). X-ray studies showed that maximum deviations among structural molecular parameters of (1) and (2) correspond to torsion angles along the C20—C22 bonds, leading to a different relative orientation of the N atom; a critical structural parameter for the binding properties of aza-sterols to Δ24(25) sterol methyl transferase. Cremer–Pople parameters of the five-membered rings of (1) and (2) lie in the observed range for a family of tetracyclic fused ring systems retrieved from the CSD. The φ2 parameter of (1) lies just on the mean of the family, while φ2 of (2) deviates significantly towards the lower limit.

ACID METABOLISM OF McINTOSH APPLES DURING THEIR DEVELOPMENT ON THE TREE AND IN COLD STORAGE

1951 ◽  
Vol 29 (1) ◽  
pp. 79-90 ◽  
Author(s):  
G. Krotkov ◽  
D. G. Wilson ◽  
R. W. Street
Keyword(s):  
Chemical Composition ◽  
Organic Acids ◽  
Cold Storage ◽  
Malic Acid ◽  
Apple Juice ◽  
Acid Metabolism ◽  
Titratable Acidity ◽  
Physiological Age ◽  
A Value ◽  
Fruit Setting

From the time of fruit setting early in the spring and throughout the whole summer, samples of fruits were taken directly from the tree. In the fall several bushels of apples were picked and placed in cold storage. These constituted the source of material during the winter. Weekly samples of fruits were analyzed for pH and titratable acidity of their sap, and also for their organic acids content. Various stages in the acid metabolism of fruits were found to correspond chronologically very closely with those of carbohydrate and respiration. During the first two to four weeks of the fruit ontogeny, the pH of the apple juice falls rapidly to a value of about 2.8. Thereafter there is a slow, steady rise which continues until the next spring. This regularity makes the pH of the juice a better indicator of the physiological age of a fruit than either its chemical composition or respiratory rate. Initially, the malic acid content of a fruit is low, and some unknown organic acids predominate. This relation is reversed within the first two to four weeks of growth and during the rest of the ontogeny malic acid forms about 80% of the total organic acids of a fruit.

Derivatives and Parameter Designs of Arbitrary Cross-Section Inhomogenous Beams’ Modes

2013 ◽  
Author(s):  
J. W. Xing ◽  
G. T. Zheng
Keyword(s):  
Cantilever Beam ◽  
Cross Section ◽  
Analytical Solutions ◽  
Structural Parameters ◽  
Arbitrary Cross Section ◽  
Mode Shapes ◽  
Design Parameters ◽  
Structural Parameter ◽  
Highly Sensitive ◽  
Sensitivity Analysis Method

As highly sensitive to structural parameter variations, it is necessary to study relations between derivatives of displacement modes and structural design parameters. This paper proposes an integral technique for obtaining the analytical solutions of slope and curvature modes of arbitrary cross-section inhomogeneous cantilever beam. The method is validated by comparing the computation results of modal frequencies and shapes with both numerical and analytical solutions. Furthermore, based on the presented method, we have established explicit expressions for the structural parameters sensitivity of the slope/curvature mode shapes. An example of parameter design is also presented for a cantilever beam with the proposed sensitivity analysis method.

Blood Pressure Parameters as Determinants of Small Artery Structure in Human Essential Hypertension

1997 ◽  
Vol 92 (6) ◽  
pp. 551-557 ◽  
Author(s):  
Anne Cooper ◽  
Anthony M. Heagerty
Keyword(s):  
Blood Pressure ◽  
Essential Hypertension ◽  
Pulse Pressure ◽  
Structural Parameters ◽  
Structural Parameter ◽  
Pressure Measurements ◽  
Significant Determinant ◽  
Small Artery ◽  
Small Arteries ◽  
Blood Pressures

1. Adaptive changes in small arteries may be more closely correlated with pulse pressure than with systolic, diastolic or mean blood pressures in human essential hypertension. 2. An analysis was performed on the structure of small arteries, age and blood pressure measurements obtained from 56 patients with untreated essential hypertension and 56 matched normotensive volunteers to examine the association between age, blood pressure and small artery structural parameters. 3. Essential hypertension was associated with an increase in media thickness and a decrease in lumen diameter, resulting in an increase in media/lumen ratio. 4. There was a significant correlation between age and media/lumen ratio in normotensive volunteers but not in patients with essential hypertension. 5. There was no correlation between any blood pressure and structural parameter in normotensive volunteers. 6. Both diastolic and mean blood pressures in essential hypertension correlated with media/lumen ratio (P < 0.01); systolic blood pressure correlated less well (P < 0.02). However, pulse pressure did not correlate with media/lumen ratio, suggesting that it is not a significant determinant of small artery structure in untreated essential hypertension.

Study on Relationship between Structural Parameter and Performance of Gas-Solid Separator

2011 ◽  
Vol 415-417 ◽  
pp. 1516-1520
Author(s):  
Xue Ping Wang ◽  
Zhen Wei Zhang
Keyword(s):  
Numerical Simulation ◽  
Gas Flow ◽  
Separation Efficiency ◽  
Structural Parameters ◽  
Structural Parameter ◽  
Exhaust Pipe ◽  
Cyclone Separator ◽  
Structure Parameter ◽  
Gas Field ◽  
And Performance

This paper mainly focuses on the numerical simulation of the gas flow field of cyclone separator. The authors took advanced of RSM turbulence model of software Fluent to simulate the gas field. The regulations among structure parameter of exhaust pipe, pressure lose and separation efficiency can be obtained according to the numerical simulation results under the situation of changing the structural parameters. The conclusion of this paper can put forward the theoretical reference for the structure optimization of cyclone separation.

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