scholarly journals Hydrolyzing metal salts as coagulants

2001 ◽  
Vol 73 (12) ◽  
pp. 2017-2026 ◽  
Author(s):  
John Gregory ◽  
Jinming Duan
Keyword(s):  
Mode Of Action ◽  
Metal Ion ◽  
Colloidal Particles ◽  
Experimental Studies ◽  
Water And Wastewater Treatment ◽  
Charge Neutralization ◽  
Charged Colloids ◽  
Coagulant Dosage ◽  
Metal Ion Hydrolysis

Aluminium and ferric salts are widely used as coagulants in water and wastewater treatment. They are effective in removing a broad range of impurities from water, including colloidal particles and dissolved organic substances. Their mode of action is broadly understood in terms of essentially two mechanisms: charge neutralization of negatively charged colloids by cationic hydrolysis products and incorporation of impurities in an amorphous precipitate of metal hydroxide. The relative importance of these two mechanisms depends on many factors, especially pH and coagulant dosage. Alternative coagulants based on prehydrolyzed forms of aluminium or iron can be more effective than the traditional materials in many cases, but their mode of action is not completely understood, especially with regard to the role of charge neutralization and hydroxide precipitation. Basic principles of colloid stability and metal ion hydrolysis are briefly reviewed, and the action of hydrolyzing metal coagulants is then discussed, with some examples from recent experimental studies. Although it is possible to interpret results reasonably well in terms of established ideas, there are still some uncertainties that need to be resolved

Effect of colloids on radionuclide migration for performance assessment of HLW disposal in Japan

2001 ◽  
Vol 73 (12) ◽  
pp. 2027-2037 ◽  
Author(s):  
S. Kurosawa ◽  
S. Ueta
Keyword(s):  
Performance Assessment ◽  
Metal Ion ◽  
Fractured Rock ◽  
Experimental Studies ◽  
Radionuclide Migration ◽  
Metal Ion Hydrolysis ◽  
Engineered Barrier ◽  
Bentonite Colloid ◽  
Major Factors ◽  
High Level

Colloidal effect is one of the major factors to enhance the migration of radionuclides in groundwater. The experimental and theoretical studies of colloid mobility and colloid-facilitated radionuclide transport for the performance assessment of high-level radioactive waste (HLW) geological disposal is presented in this paper. The major aims of the study are (1) to study the filtration effect on colloids by the engineered barrier system, (2) to study bentonite colloid generation by erosion of the engineered barrier system, and (3) to calculate radionuclide migration with groundwater colloids through fractured rock systems. Alternative coagulants based on prehydrolyzed forms of aluminium or iron can be more effective than the traditional materials in many cases, but their mode of action is not completely understood, especially with regard to the role of charge neutralization and hydroxide precipitation. Basic principles of colloid stability and metal ion hydrolysis are briefly reviewed, and the action of hydrolyzing metal coagulants is then discussed, with some examples from recent experimental studies. Although it is possible to interpret results reasonably well in terms of established ideas, there are still some uncertainties that need to be resolved

Extraction and separation of metal cations in solution by supported liquid membrane using lasalocid A as carrier

2001 ◽  
Vol 73 (12) ◽  
pp. 2039-2046 ◽  
Author(s):  
L. Canet ◽  
P. Seta
Keyword(s):  
Metal Cation ◽  
Metal Ion ◽  
Hydration Shell ◽  
Experimental Studies ◽  
Metal Cations ◽  
Metal Species ◽  
Extraction And Separation ◽  
Supported Liquid Membranes ◽  
Metal Ion Hydrolysis ◽  
Na Ions

Flat-sheet-supported liquid membranes incorporating lasalocid A (a natural ionophore), were previously shown to be permeable to metal cations (Cd2+ and Zn2+) against a proton gradient (DpH), which is the driving force of the process [1]. This transport process has been extended to other metal species such as Pb2+, Na+, and Ag+ and also to the case where two metal species compete for transport. A higher transport flux for Pb2+ as compared to Cd2+ and Zn2+ is observed and partly explained by a higher rate of interfacial complexation owing to the smaller hydration shell of this species. This effect is confirmed by the data obtained with Ag+. However, the size of the metal cation in relation to its hydration shell does not appear as the major parameter to take into account for an estimate of the trans-membrane transport efficiency, as the Na+ ions escape to this behavior, which has been considered until now as a general trend for metal cation ionophores. Alternative coagulants based on prehydrolyzed forms of aluminium or iron can be more effective than the traditional materials in many cases, but their mode of action is not completely understood, especially with regard to the role of charge neutralization and hydroxide precipitation. Basic principles of colloid stability and metal ion hydrolysis are briefly reviewed, and the action of hydrolyzing metal coagulants is then discussed, with some examples from recent experimental studies. Although it is possible to interpret results reasonably well in terms of established ideas, there are still some uncertainties that need to be resolved

Calculation-and-experimental estimation of the role of the frequency ratio in changing the endurance at two-frequency deformation modes

2019 ◽  
Vol 85 (1(I)) ◽  
pp. 64-71 ◽  
Author(s):  
M. M. Gadenin
Keyword(s):  
High Frequency ◽  
Experimental Studies ◽  
Low Frequency ◽  
Reduction Factor ◽  
Single Frequency ◽  
Cyclic Loads ◽  
Small Ratio ◽  
Harmonic Components ◽  
Deformation Modes

The cycle configuration at two-frequency loading regimes depends on the number of parameters including the absolute values of the frequencies and amplitudes of the low-frequency and high-frequency loads added during this mode, the ratio of their frequencies and amplitudes, as well as the phase shift between these harmonic components, the latter having a significant effect only with a small ratio of frequencies. Presence of such two-frequency regimes or service loading conditions for parts of machines and structures schematized by them can significantly reduce their endurance. Using the results of experimental studies of changes in the endurance of a two-frequency loading of specimens of cyclically stable, cyclically softened and cyclically hardened steels under rigid conditions we have shown that decrease in the endurance under the aforementioned conditions depends on the ratio of frequencies and amplitudes of operation low-frequency low-cycle and high-frequency vibration stresses, and, moreover, the higher the level of the ratios of amplitudes and frequencies of those stacked harmonic processes of loading the greater the effect. It is shown that estimation of such a decrease in the endurance compared to a single frequency loading equal in the total stress (strains) amplitudes can be carried out using an exponential expression coupling those endurances through a parameter (reduction factor) containing the ratio of frequencies and amplitudes of operation cyclic loads and characteristic of the material. The reduction is illustrated by a set of calculation-experimental curves on the corresponding diagrams for each of the considered types of materials and compared with the experimental data.

Helping when desire is low: The role of Expectancy in helping

2020 ◽  
Author(s):  
Małgorzata Kossowska
Keyword(s):  
Experimental Studies ◽  
Helping Behavior ◽  
Perceived Effectiveness ◽  
Do So

One might assume that the desire to help (here described as Want) is the essential driver of helping declarations and/or behaviors. However, even if desire to help is low, helping behavior may still occur if the expectancy regarding the perceived effectiveness of helping is high. We tested these predictions in a set of three experimental studies. In all three, we measured the desire to help (Want) and the Expectancy that the aid would be impactful for the victim; in addition, we manipulated Expectancy in Study 3. In Studies 1 and 3, we measured the participants’ declaration to help while in Study 2, their helping behavior was examined. In all three studies, we used variations of the same story about a victim. The results supported our hypothesis. Thus, the studies help to tease apart the determinants of helping behavior under conditions of lowered desire to do so, an issue of great importance in public policymaking.

The capacity of short term memory from an evolutionary perspective

2019 ◽  
Author(s):  
Majid Manoochehri
Keyword(s):  
Short Term Memory ◽  
Memory Span ◽  
Critical Role ◽  
Experimental Studies ◽  
Cognitive System ◽  
Evolutionary Approach ◽  
Evolutionary Perspective ◽  
Short Term ◽  
Term Memory

Memory span in humans has been intensely studied for more than a century. In spite of the critical role of memory span in our cognitive system, which intensifies the importance of fundamental determinants of its evolution, few studies have investigated it by taking an evolutionary approach. Overall, we know hardly anything about the evolution of memory components. In the present study, I briefly review the experimental studies of memory span in humans and non-human animals and shortly discuss some of the relevant evolutionary hypotheses.

The methodology of experimental research of the feed components extrusion process in order to improve its energy performance

2020 ◽  
pp. 147-152
Author(s):  
E. M. Ratnikov ◽  
D. O. Milko
Keyword(s):  
Experimental Studies ◽  
Energy Performance ◽  
Extrusion Process ◽  
Mathematical Methods ◽  
Screw Extruder ◽  
Mathematical Planning ◽  
Factors Affecting ◽  
Extrusion Processing ◽  
Definition Of

Annotation Purpose. Development of a program and methods for conducting experimental studies of the extrusion process with the definition of parameters and modes of operation of the extruder to improve its energy performance. Methods. Methods of mathematical statistics, synthesis, analysis, description and modeling were used. Results. The application of mathematical methods, in particular mathematical planning, reduces the number of experiments several times, and allows to evaluate the role of influencing factors, obtain a mathematical model of the process and determine the optimal conditions for its parameters and modes, etc. Conclusions. The methodology for experimental studies of a screw extruder is presented with the necessary equipment and methodology for processing the obtained experimental data. A mathematical method of planning, which reduces the number of experiments several times, allows us to evaluate the role of factors affecting productivity and energy intensity is presented. Keywords: extruder, auger, nutrients, research methodology, extrusion, processing, feed.

ACE2/Angiotensin-(1-7)/Mas Receptor Axis in Human Cancer: Potential Role for Pediatric Tumors

2020 ◽  
Vol 21 (9) ◽  
pp. 892-901 ◽  
Author(s):  
Ana Luiza Ataide Carneiro de Paula Gonzaga ◽  
Vitória Andrade Palmeira ◽  
Thomas Felipe Silva Ribeiro ◽  
Larissa Braga Costa ◽  
Karla Emília de Sá Rodrigues ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Angiotensin Ii ◽  
Pediatric Cancer ◽  
Pediatric Patients ◽  
Human Cancer ◽  
Experimental Studies ◽  
At1 Receptor ◽  
Pediatric Tumors ◽  
Mas Receptor

Background: Pediatric tumors remain the highest cause of death in developed countries. Research on novel therapeutic strategies with lesser side effects is of utmost importance. In this scenario, the role of Renin-Angiotensin System (RAS) axes, the classical one formed by angiotensinconverting enzyme (ACE), Angiotensin II and AT1 receptor and the alternative axis composed by ACE2, Angiotensin-(1-7) and Mas receptor, have been investigated in cancer. Objective: This review aimed to summarize the pathophysiological role of RAS in cancer, evidence for anti-tumor effects of ACE2/Angiotensin-(1-7)/Mas receptor axis and future therapeutic perspectives for pediatric cancer. Methods: Pubmed, Scopus and Scielo were searched in regard to RAS molecules in human cancer and pediatric patients. The search terms were “RAS”, “ACE”, “Angiotensin-(1-7)”, “ACE2”, “Angiotensin II”, “AT1 receptor”, “Mas receptor”, “Pediatric”, “Cancer”. Results: Experimental studies have shown that Angiotensin-(1-7) inhibits the growth of tumor cells and reduces local inflammation and angiogenesis in several types of cancer. Clinical trials with Angiotensin-( 1-7) or TXA127, a pharmaceutical grade formulation of the naturally occurring peptide, have reported promising findings, but not enough to recommend medical use in human cancer. In regard to pediatric cancer, only three articles that marginally investigated RAS components were found and none of them evaluated molecules of the alternative RAS axis. Conclusion: Despite the potential applicability of Angiotensin-(1-7) in pediatric tumors, the role of this molecule was never tested. Further clinical trials are necessary, also including pediatric patients, to confirm safety and efficiency and to define therapeutic targets.

Family Influences on Youth Offending

2018 ◽  
pp. 377-403
Author(s):  
Abigail A. Fagan ◽  
Kristen M. Benedini
Keyword(s):  
Life Course ◽  
Family Environment ◽  
Parenting Practices ◽  
Experimental Studies ◽  
The United States ◽  
Parental Violence ◽  
Youth Delinquency ◽  
The Impact ◽  
Children’S Exposure

This chapter reviews the degree to which empirical evidence demonstrates that families influence youth delinquency. Because they are most likely to be emphasized in life-course theories, this chapter focuses on parenting practices such as parental warmth and involvement, supervision and discipline of children, and child maltreatment. It also summarizes literature examining the role of children's exposure to parental violence, family criminality, and young (teenage) parents in affecting delinquency. Because life-course theories are ideally tested using longitudinal data, which allow examination of, in this case, the impact of parenting practices on children's subsequent behaviors, this chapter focuses on evidence generated from prospective studies conducted in the United States and other countries. It also discusses findings from experimental studies designed to reduce youth substance use and delinquency by improving the family environment.

scholarly journals The Gene Regulatory Roles of Herbal Extracts on the Growth, Immune System, and Reproduction of Fish

Animals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2167
Author(s):  
Ehsan Ahmadifar ◽  
Hamideh Pourmohammadi Fallah ◽  
Morteza Yousefi ◽  
Mahmoud A. O. Dawood ◽  
Seyed Hossein Hoseinifar ◽  
...  
Keyword(s):  
Immune System ◽  
Mode Of Action ◽  
Medicinal Herbs ◽  
Environmental Stressors ◽  
Fish Diet ◽  
Sustainable Aquaculture ◽  
Herbal Supplements ◽  
Aquatic Animals ◽  
Gene Regulatory

The crucial need for safe and healthy aquatic animals obligates researchers in aquaculture to investigate alternative and beneficial additives. Medicinal herbals and their extracts are compromised with diverse effects on the performances of aquatic animals. These compounds can affect growth performance and stimulate the immune system when used in fish diet. In addition, the use of medicinal herbs and their extracts can reduce oxidative stress induced by several stressors during fish culture. Correspondingly, aquatic animals could gain increased resistance against infectious pathogens and environmental stressors. Nevertheless, the exact mode of action where these additives can affect aquatic animals’ performances is still not well documented. Understanding the mechanistic role of herbal supplements and their derivatives is a vital tool to develop further the strategies and application of these additives for feasible and sustainable aquaculture. Gene-related studies have clarified the detailed information on the herbal supplements’ mode of action when administered orally in aquafeed. Several review articles have presented the potential roles of medicinal herbs on the performances of aquatic animals. However, this review article discusses the outputs of studies conducted on aquatic animals fed dietary, medicinal herbs, focusing on the gene expression related to growth and immune performances. Furthermore, a particular focus is directed to the expected influence of herbal supplements on the reproduction of aquatic animals.

Sign in / Sign up

Export Citation Format

Share Document