scholarly journals Pump-and-Treat remediation of groundwater contaminated by hazardous waste: can it really be achieved?

2013 ◽  
Vol 3 (1) ◽  
pp. 1-10 ◽  
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Hazardous Waste ◽  
Chemical Properties ◽  
Water Soluble ◽  
Hazardous Wastes ◽  
Model Simulations ◽  
Pump And Treat ◽  
Small Parts

Pump-and-treat (P&T) is one of the most common methods for remediation of groundwater contaminated by hazardous wastes. However, this method suffers from serious disadvantages, due a series of subsurface processes. Using experimental data and mathematical model simulations, the role of sorption/ desorption and dissolution of non-aqueous phase liquids on the effectiveness of P&T remediation was examined. The results showed that the remediation of groundwater depends directly on the physical/ chemical properties of the contaminants and the hydrogeology of the site. With the exception of water-soluble contaminants occupying relatively small parts of relatively homogeneous and water-permeable geologic media, the remediation of groundwater contaminated by hazardous waste using P&T is, for all practical purposes, impossible and prohibitively expensive.

scholarly journals The Multi-Level Mechanism of Action of a Pan-Ras Inhibitor Explains its Antiproliferative Activity on Cetuximab-Resistant Cancer Cells

2021 ◽  
Vol 8 ◽  
Author(s):  
Renata Tisi ◽  
Michela Spinelli ◽  
Alessandro Palmioli ◽  
Cristina Airoldi ◽  
Paolo Cazzaniga ◽  
...  
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Cancer Cells ◽  
Water Soluble ◽  
Downstream Signaling ◽  
Ras Activation ◽  
Multi Level ◽  
Activation Cycle ◽  
Effector Binding ◽  
Ras Inhibitors

Ras oncoproteins play a crucial role in the onset, maintenance, and progression of the most common and deadly human cancers. Despite extensive research efforts, only a few mutant-specific Ras inhibitors have been reported. We show that cmp4–previously identified as a water-soluble Ras inhibitor– targets multiple steps in the activation and downstream signaling of different Ras mutants and isoforms. Binding of this pan-Ras inhibitor to an extended Switch II pocket on HRas and KRas proteins induces a conformational change that down-regulates intrinsic and GEF-mediated nucleotide dissociation and exchange and effector binding. A mathematical model of the Ras activation cycle predicts that the inhibitor severely reduces the proliferation of different Ras-driven cancer cells, effectively cooperating with Cetuximab to reduce proliferation even of Cetuximab-resistant cancer cell lines. Experimental data confirm the model prediction, indicating that the pan-Ras inhibitor is an appropriate candidate for medicinal chemistry efforts tailored at improving its currently unsatisfactory affinity.

scholarly journals Mathematical Model Explaining the Role of CDC6 in the Diauxic Growth of CDK1 Activity during the M-Phase of the Cell Cycle

Cells ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 1537 ◽  
Author(s):  
Mateusz Dębowski ◽  
Zuzanna Szymańska ◽  
Jacek Z. Kubiak ◽  
Mirosław Lachowicz
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Regulatory Protein ◽  
Mass Action ◽  
Cyclin B ◽  
Mass Action Kinetics ◽  
Mitotic Entry ◽  
M Phase ◽  
New Hypothesis

In this paper we propose a role for the CDC 6 protein in the entry of cells into mitosis. This has not been considered in the literature so far. Recent experiments suggest that CDC 6 , upon entry into mitosis, inhibits the appearance of active CDK 1 and cyclin B complexes. This paper proposes a mathematical model which incorporates the dynamics of kinase CDK 1 , its regulatory protein cyclin B, the regulatory phosphatase CDC 25 and the inhibitor CDC 6 known to be involved in the regulation of active CDK 1 and cyclin B complexes. The experimental data lead us to formulate a new hypothesis that CDC 6 slows down the activation of inactive complexes of CDK 1 and cyclin B upon mitotic entry. Our mathematical model, based on mass action kinetics, provides a possible explanation for the experimental data. We claim that the dynamics of active complexes CDK 1 and cyclin B have a similar nature to diauxic dynamics introduced by Monod in 1949. In mathematical terms we state it as the existence of more than one inflection point of the curve defining the dynamics of the complexes.

Modelling of the Ventilation Unit for a Stand Alone Solar Collector

2013 ◽  
Vol 330 ◽  
pp. 687-692 ◽  
Author(s):  
Jean Louis Canaletti ◽  
Christian Cristofari ◽  
Gilles Notton
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Energy Balance ◽  
Low Temperature ◽  
Solar Collector ◽  
Main Role ◽  
Balance Equations ◽  
Temperature Heat ◽  
Long Time

The work described in this paper concerns a part of the modelling of a standalone air solar collector producing low temperature heat. The main role of the system is to avoid freezing temperatures and to reduce humidity in a room or in an unoccupied home during a long time, with only solar radiation. In view to dispose an essential sizing tool for this solar collector, we developed a mathematical model based on energy balance equations and on the characteristics of the system. This model allows simulation of the aerolic and thermal behaviour of the solar collector. It was validated using experimental data collected by telemetry in six operating sites. We present here the behaviour model of the ventilation unit part.

scholarly journals The role of antioxidant molecules in the treatment of male infertility and the preparation of a man for conception

2020 ◽  
pp. 122-129
Author(s):  
S. I. Gamidov ◽  
T. V. Shatylko ◽  
K. I. Li ◽  
N. G. Gasanov
Keyword(s):  
Male Infertility ◽  
Hypogonadotropic Hypogonadism ◽  
Chemical Properties ◽  
Empirical Therapy ◽  
The Body ◽  
Water Soluble ◽  
Semen Parameters ◽  
Wide Range ◽  
Antioxidant Supplements

Empirical therapy of male infertility is used as a stand-alone type of treatment in idiopathic infertility, and in other situations can complement basic therapy. There are well-known pathogenetic methods of male infertility treatment applied in case of reproductive gland infection, hypogonadotropic hypogonadism, ejaculation disorders. However, the prospects of empirical treatment of male infertility are not fully clear. Combined antioxidant drugs are very popular, which include a wide range of similar substances. However, their molecules significantly differ from each other in structure, chemical properties and set of biological functions, therefore, there is a number of questions that deserve separate discussion regarding their compatibility with each other. Antioxidants such as various water-soluble and fat-soluble vitamins, coenzyme Q10, zinc and carnitines are widely used in its composition to reduce sperm damage caused by oxidative stress. They are widely available and inexpensive compared to other methods of treatment. Although there are no results of large randomized controlled trials yet, there is some evidence that taking oral antioxidoidants improves the basic parameters of sperm and increases the frequency of childbirth. There are many antioxidant supplements in different dosage forms, with different compositions and modes of use. In this article, we have analyzed the effect of the main antioxidant substances used on semen parameters, the need for their combined use and the role of these substances in the body.

The Impact of Light Polarisation on Light Field of Scenes with Multiple Reflections

2020 ◽  
pp. 108-115 ◽  
Author(s):  
Vladimir P. Budak ◽  
Anton V. Grimaylo
Keyword(s):  
Mathematical Model ◽  
Light Field ◽  
Global Illumination ◽  
Multiple Reflections ◽  
Software Environment ◽  
The Monte Carlo Method ◽  
Mueller Matrices ◽  
Volume Integration ◽  
The Impact

The article describes the role of polarisation in calculation of multiple reflections. A mathematical model of multiple reflections based on the Stokes vector for beam description and Mueller matrices for description of surface properties is presented. On the basis of this model, the global illumination equation is generalised for the polarisation case and is resolved into volume integration. This allows us to obtain an expression for the Monte Carlo method local estimates and to use them for evaluation of light distribution in the scene with consideration of polarisation. The obtained mathematical model was implemented in the software environment using the example of a scene with its surfaces having both diffuse and regular components of reflection. The results presented in the article show that the calculation difference may reach 30 % when polarisation is taken into consideration as compared to standard modelling.

Characteristics Of The Structure Formation Of Gypsum Binder Modified With Zinc Hydrosilicates

2020 ◽  
pp. 40-46
Keyword(s):  
Synergistic Effect ◽  
Physicochemical Properties ◽  
Structure Formation ◽  
Silicic Acid ◽  
Chemical Properties ◽  
Crystal Formation ◽  
Ability To Act ◽  
Chemical Factors ◽  
Sorption Characteristics

The authors' methodic for assessing the role of chemical and physic-chemical factors during the structure formation of gypsum stone is presented in the article. The methodic is also makes it possible to reveal the synergistic effect and to determine the ranges of variation of controls factors that ensure maximum values of such effect. The effect of a micro-sized modifier based on zinc hydro-silicates on the structure formation of building gypsum is analyzed and corresponding dependencies are found. It is shown that effects of influence of modifier on the properties of gypsum compositions are determined by chemical properties of modifier. Among the mentioned properties are sorption characteristics (which depend on the amount of silicic acid and its state) and physicochemical properties - the ability to act as a substrate during crystal formation. The proposed method can also be extended to other binding substances and materials. This article contributes to the understanding of the processes that occur during the structure formation of composites, which will make it possible to control the structure formation in the future, obtaining materials with a given set of properties.

The Nature of S-N Bonding in Sulfonamides and Related Compounds: Insights into π-Bonding Contributions from Sulfur K-Edge XAS

2020 ◽  
Author(s):  
Tulin Okbinoglu ◽  
Pierre Kennepohl
Keyword(s):  
Density Functional ◽  
Chemical Properties ◽  
Functional Theory ◽  
Rotational Barriers ◽  
Td Dft ◽  
Nitrogen Bonds ◽  
X Ray Absorption ◽  
Related Compounds ◽  
And Chemical Properties

Molecules containing sulfur-nitrogen bonds, like sulfonamides, have long been of interest due to their many uses and chemical properties. Understanding the factors that cause sulfonamide reactivity is important, yet their continues to be controversy regarding the relevance of S-N π bonding in describing these species. In this paper, we use sulfur K-edge x-ray absorption spectroscopy (XAS) in conjunction with density functional theory (DFT) to explore the role of S<sub>3p</sub> contributions to π-bonding in sulfonamides, sulfinamides and sulfenamides. We explore the nature of electron distribution of the sulfur atom and its nearest neighbors and extend the scope to explore the effects on rotational barriers along the sulfur-nitrogen axis. The experimental XAS data together with TD-DFT calculations confirm that sulfonamides, and the other sulfinated amides in this series, have essentially no S-N π bonding involving S<sub>3p</sub> contributions and that electron repulsion and is the dominant force that affect rotational barriers.

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