PHYSICO-CHEMICAL MECHANISMS IN THE PATHOGENESIS OF CERTAIN HEMOLYTIC ANEMIAS

AbstractShallow aquifers are vulnerable to natural geogenic processes as well as anthropogenic influences, and this is especially apparent in desert regions. Within arid and hyperarid climates, evaporation is a controlling hydrologic process leads to an important increase in the concentration of dissolved minerals of both surface water and groundwater. In groundwater, this increase is not only dependent on shallow water table depth, but also on the hydraulic properties of sediments present within the unsaturated zone of the aquifer itself. The main objective of this research is to investigate possible mechanisms that might influence water quality changes under seasonal conditions in shallow aquifers situated within the Saharan desert region of Algeria. In this work, we focus on observed changes in hydrogeochemical characteristics, and the possible responsible processes. Under arid conditions, high water mineralization results in hypersaline water or brine solution formation within shallow aquifers. Due to active physico-chemical mechanisms such as Na+/Ca2+ ion exchange, the successive precipitation of calcite, gypsum, mirabilite or blœdite and halite is induced. Biological processes were also observed as prevalent; evidenced by large measured variations in CO2 load concentrations. These processes contributed to an inverse relationship between CO2 and O2 concentrations within the shallow aquifers studied.

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Chemical phosphorus removal model based on equilibrium chemistry

Water Science & Technology ◽

10.2166/wst.2005.0735 ◽

2005 ◽

Vol 52 (10-11) ◽

pp. 549-555 ◽

Cited By ~ 5

Author(s):

I. Takács ◽

S. Murthy ◽

P.M. Fairlamb

Keyword(s):

Phosphorus Removal ◽

Dissociation Constants ◽

Chemical Precipitation ◽

Weak Acid ◽

Chemical Mechanisms ◽

Model Based ◽

Precipitation Model ◽

Physico Chemical ◽

Ph Range ◽

Biological Methods

Regulations in many regions of the world require total phosphorus (TP) levels lower than 0.10mgP/L (100μgP/L) in effluents, resulting in the need to achieve very low ortho-phosphate (OP) concentrations. Chemical precipitation is a widely used technology for controlling effluent OP discharge, either on its own or supplementing biological methods. The various chemical and physico-chemical mechanisms that result in extremely low residual OP levels are complex and depend on pH. In practice, engineering calculations frequently use an empirical precipitation model. This model requires pH as input and predicts the lowest achievable OP residual of 35μgP/L at a narrow optimum pH of 6.9 – 7.0, when an excess of ferric is added. The model has been combined with a biokinetic and weak acid/base chemistry based pH model, to allow accurate prediction of pH, OP residuals and chemical sludge production. Analysis of effluent data from the Blue Plains plant shows that residuals as low as 10μgP/L OP can be achieved regularly, over a wider pH range. The precipitation model was recalibrated to match the newly available data. Subsequently it was compared with a new, mechanistic precipitation model based on solubility and dissociation constants for actual chemical compounds. The need for more accurate measurement of extremely low OP concentrations and considering the role of organics, adsorption and coagulation in chemical phosphorus removal is demonstrated.

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An overview of physico-chemical mechanisms of biogas production by microbial communities: a step towards sustainable waste management

3 Biotech ◽

10.1007/s13205-016-0395-9 ◽

2016 ◽

Vol 6 (1) ◽

Cited By ~ 25

Author(s):

Ramansu Goswami ◽

Pritam Chattopadhyay ◽

Arunima Shome ◽

Sambhu Nath Banerjee ◽

Amit Kumar Chakraborty ◽

...

Keyword(s):

Waste Management ◽

Microbial Communities ◽

Biogas Production ◽

Sustainable Waste Management ◽

Chemical Mechanisms ◽

Physico Chemical

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Chemical Mechanisms of Nanoparticle Radiosensitization and Radioprotection: A Review of Structure-Function Relationships Influencing Reactive Oxygen Species

International Journal of Molecular Sciences ◽

10.3390/ijms21020579 ◽

2020 ◽

Vol 21 (2) ◽

pp. 579 ◽

Cited By ~ 12

Author(s):

Douglas Howard ◽

Sonia Sebastian ◽

Quy Van-Chanh Le ◽

Benjamin Thierry ◽

Ivan Kempson

Keyword(s):

Reactive Oxygen Species ◽

Structure Function ◽

Reactive Oxygen ◽

Metal Nanoparticle ◽

Ros Generation ◽

Oxygen Species ◽

X Rays ◽

Chemical Mechanisms ◽

Enhanced Production ◽

Physico Chemical

Metal nanoparticles are of increasing interest with respect to radiosensitization. The physical mechanisms of dose enhancement from X-rays interacting with nanoparticles has been well described theoretically, however have been insufficient in adequately explaining radiobiological response. Further confounding experimental observations is examples of radioprotection. Consequently, other mechanisms have gained increasing attention, especially via enhanced production of reactive oxygen species (ROS) leading to chemical-based mechanisms. Despite the large number of variables differing between published studies, a consensus identifies ROS-related mechanisms as being of significant importance. Understanding the structure-function relationship in enhancing ROS generation will guide optimization of metal nanoparticle radiosensitisers with respect to maximizing oxidative damage to cancer cells. This review highlights the physico-chemical mechanisms involved in enhancing ROS, commonly used assays and experimental considerations, variables involved in enhancing ROS generation and damage to cells and identifies current gaps in the literature that deserve attention. ROS generation and the radiobiological effects are shown to be highly complex with respect to nanoparticle physico-chemical properties and their fate within cells. There are a number of potential biological targets impacted by enhancing, or scavenging, ROS which add significant complexity to directly linking specific nanoparticle properties to a macroscale radiobiological result.

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Preparation of Asphalt Concretes by Gyratory Compactor: A Case of Study with Rheological and Mechanical Aspects

Applied Sciences ◽

10.3390/app10238567 ◽

2020 ◽

Vol 10 (23) ◽

pp. 8567

Author(s):

Paolino Caputo ◽

Pietro Calandra ◽

Rosolino Vaiana ◽

Vincenzo Gallelli ◽

Giovanni De Filpo ◽

...

Keyword(s):

Mechanical Properties ◽

Activation Energy ◽

Energy Savings ◽

Tensile Deformation ◽

Environmental Issues ◽

Exponential Factor ◽

Air Voids ◽

Chemical Mechanisms ◽

Physico Chemical ◽

Indirect Tensile

For asphalt concrete preparation in laboratory mix-design operations, bitumens are usually mixed with micrometer-sized particles (filler), sand and centimeter-sized crushed stones in a gyratory press at a temperature of about 140–155 °C depending on the bitumen viscosity, until adequate homogenization and compaction take place (air voids optimum). This requires energy consumption. To minimize it, the process needs to be optimized and is usually made empirically. The aim of this manuscript is to gain a comprehension of the physico-chemical mechanisms involved in the process by exploring: (i) the rheological properties (viscosity, activation energy) of a neat and RTFOT-aged bitumen, in presence and in absence of a filler, (ii) the volumetric and resistance behavior under the compaction in a standard Gyratory Compactor (GC) of their blends with aggregates and (iii) the mechanical properties (Indirect Tensile Strength, compression and tensile deformation) of the final products. Correlations between activation energy and pre-exponential factor of the viscosity on a side, and between viscosity, workability and final mechanical properties on the other side allowed to provide a rational interpretation of the physico-chemical processes involved in the framework of the physics of complex fluids. The scientific clues will be of help in optimizing the workability in asphalt concretes productions with obvious repercussions in terms of energy savings, useful for economic and environmental issues.

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THE CAMBIUM AND ITS DERIVATIVE TISSUES

The Journal of General Physiology ◽

10.1085/jgp.14.3.363 ◽

1931 ◽

Vol 14 (3) ◽

pp. 363-383 ◽

Cited By ~ 29

Author(s):

I. W. Bailey ◽

Conway Zirkle

Keyword(s):

Higher Plants ◽

Future Trends ◽

Living Plant ◽

Group Iii ◽

Chemical Mechanisms ◽

Biological Variables ◽

Group I ◽

Physico Chemical ◽

Intensive Investigation ◽

Limited Induction

It should be emphasized, in conclusion, that the writers' investigation is a reconnaissance, and was initiated primarily in searching for more adequate techniques for the study of cytological problems. Crude as many of the data undoubtedly are, they are of some significance in outlining future trends of more intensive investigation. The occurrence of two distinct types of vacuoles within the same cell provides a valuable check upon generalizations concerning the penetration of certain dyes. The A-type vacuole affords a means of determining that a number of dyes do penetrate living plant cells readily and rapidly from acid buffers. The recognition of two distinct categories of vacuoles—which are widely distributed throughout the higher plants—and a study of their staining reactions in Group I, Group II, and Group III dyes, indicate that certain discrepancies in the literature are due to the fact that different investigators are concerned with different vacuoles and with different dyes. For an accurate visualization of the physico-chemical mechanisms of the penetration and accumulation of dyes in living cells a much wider range of reliable data is essential, both as regards the purely biological variables and the physico-chemical variables in techniques employed in their investigation. Until such data are available, generalizations from limited induction should be reduced to a minimum.

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Physico-chemical mechanisms involved in the acceleration of the hydration of calcium sulfoaluminate cement by lithium ions

Cement and Concrete Research ◽

10.1016/j.cemconres.2017.03.004 ◽

2017 ◽

Vol 96 ◽

pp. 42-51 ◽

Cited By ~ 26

Author(s):

Céline Cau Dit Coumes ◽

Mélanie Dhoury ◽

Jean-Baptiste Champenois ◽

Cyrille Mercier ◽

Denis Damidot

Keyword(s):

Calcium Sulfoaluminate Cement ◽

Lithium Ions ◽

Chemical Mechanisms ◽

Calcium Sulfoaluminate ◽

Physico Chemical

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Evaluation of Mechanisms of Ice Adhesion on Power Network Equipment

23rd International Conference on Offshore Mechanics and Arctic Engineering, Volume 3 ◽

10.1115/omae2004-51267 ◽

2004 ◽

Cited By ~ 1

Author(s):

Mohammad R. Kasaai ◽

Masoud Farzaneh

Keyword(s):

Ceramic Materials ◽

Van Der Waals Interactions ◽

Power Network ◽

Chemical Mechanisms ◽

Dipole Interactions ◽

Physico Chemical ◽

Network Equipment ◽

Ceramic Insulators ◽

Interfacial Adhesion Strength ◽

Ice Adhesion

The objective of this study is to review the mechanisms of ice adhesion to cables and insulators, with a special emphasis on aluminum and ceramic materials, as these devices are made from these materials. This review shows that the physico-chemical interactions and mechanical interlock contribute to the mechanisms of ice adhesion to surfaces. The physico-chemical mechanisms of ice adhesion to surfaces are classified into three main categories: dipole-dipole or ion-dipole interactions; hydrogen bond; and van der Waals interactions. The interfacial adhesion strength of ice/metals or ice/ceramic insulators is greater than the strength of ice. This indicates that the strength between ice and the material surfaces is greater than hydrogen bonds of ice itself. The mechanical mechanism involves the penetration of liquid water into cavities and pores on the surface of the substrate and expansion of ice during solidification, resulting in an anchor effect and the establishment of a strong bond between ice and surface.

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