Physics, Astronomy, Optics and Photonics
Gold Ring and Graphite-Based Plasmonic Photonic Crystal Sensor for Biomedical Applications
This research puts forward a cost-efficient high-efficiency plasmonic photonic crystal sensor for biomedical applications that functions in the near-infrared range.
The sensor design is composed of multiple two-dimensional photonic crystal layers stacked in the order of SiO2 foundational layer graphite layer MgF2 waveguide and finally a gold ring over the top. The graphite layer is deposited for optimum sensing and high absorption peaks and is state-of-the-art in this research work. Metal deposition of the gold layer is used for harnessing plasmonic properties that play a vital role in detecting small refractive index changes.
The sensor design is investigated for a range of coupling incident angles and it is found that the sensor is responsive to a broad range of angles i.e. 0o to 80o. The proposed sensor has given output peak values of more than 90% in the whole range of incident source angles.
Finally water and 25% concentration of glucose samples are used for investigating sensor performance and it is noted that the sensor’s sensitivity reaches as high as 1675 nm/RIU-1 with a Figure of Merit (FOM) of 20.94 RIU-1. The sensor’s numerical simulations have been performed using Finite Element Method (FEM) and Finite Difference Time Domain (FDTD).
Creation of Technology and Devices for the Preparation of Motor Fuels Containing Biocomponents
In the world active research is being conducted to create motor fuels containing bio-oil as a component derived from renewable environmentally friendly sources of raw materials such as wood processing waste agriculture marine algae etc. One of the most commonly used technologies for bio-oil production is fast pyrolysis. Due to the physical and chemical properties of such bio-oil direct blending with petroleum motor fuel is not possible.
The goal of the conducted research was to develop technology and devices to address this issue. Fundamental developments in the field of nonlinear wave mechanics formed the basis for these endeavors.
During the research designs for motor fuel preparation devices were developed and mathematical modeling of the mixing processes of fuel components was carried out. The obtained data were analyzed and transferred to natural samples which were examined during experiments.
As a result blended fuels based on bio-oil (up to 15% by weight) and diesel fuel (marine) with stability of up to 10 days without the use of surface-active substances (SF) and 25-30 days with the addition of SF (up to 0.5% by weight) were obtained.
Fuel containing SF is re-homogenized by traditional stirring for at least 3 months. The obtained results confirmed the correctness of the chosen approach and the feasibility of using the developed technology for preparing blended motor fuel containing bio-oil.
Quantum-Mechanical Explanation of Young’s double slit Experiment through Simulation of the Photon Coordinate Wave Function
In the rapidly developing areas of photonics associated with quantum teleportation of photons quantum cryptography and quantum computing ideas are becoming increasingly relevant about the certain localized states of single or several entangled photons moving in space and time. As is known in quantum mechanics localized states of particles can only be described using wave functions in coordinate representation – the corresponding wave packets.
To explain Young's one- and two-photon experiments using coordinate 6-component quantum mechanical and 1-component quasi-classical photon wave functions.
The article outlines the method developed in authors' previous work in constructing the 6-component coordinate wave function of free photons in the form of the wave packet (an integral over the entire momentum space and sum over two possible values +1 and -1 of the helicity). The basis functions are the circularly polarized monochromatic waves corresponding to certain values of the momentum helicity and photon energy operators and forming a complete orthonormal set of generalized eigenfunctions of these operators. This photon wave function (PWF) is normalized to the unit probability of finding the photon anywhere in space. Both the basis functions and the coordinate PWF satisfy a Schrödinger-type equation derived from the Maxwell-Lorentz equations written in quantum mechanical form first introduced by Majorana. Then the results of modeling and consideration of the space-time evolution of the wave packet with Gaussian momentum distribution corresponding to the directed photon emission for 80 fs are briefly presented. Further in view of the possibility of constructing the coordinate PWF the basic formula for the wave-particle duality of photons and particles is formulated. It is emphasized that the photon is fundamentally different from “ordinary” particles since according to the authors the photon is the result of the propagation of a certain complex spin wave in a physical vacuum the details of which can only be considered simultaneously with the study of the structure of the physical vacuum at Planckian distances.
Young's one- and two-photon experiments are explained using various options for modeling 6-component coordinate PWFs including approximate functions corresponding to spherically symmetric and electric dipole photon radiation.
This explanation is illustrated using specific examples of radiation and at the same time is compared with numerical simulations for spherically symmetric radiation and the use of 1-component quasi-classical PWFs.
Aero-space and Astro-cosmic Microbial Studies: A Vulgar Epithet Yet an Unattended Potential Nursing/Distribution Hub of Pathogenic Strains
The ubiquity of microorganisms has in recent times extended relevance from the physical environment to outer space/cosmic environment. Such outer space/cosmic environments were over time reported microbe free however recent report showed otherwise implicating space/cosmic travel.
Diverse interest-based investigators have raised unanswered questions while others yet remain probable. Bio-scientific evaluation of astro-cosmic dynamics possesses the potential of revealing the appropriate status arrangement and/or position of microbes especially as global drives focus on controlling microbial spread/proliferation.
The study determines microbes in space and astro-cosmic environment as vulgar epithet yet an unattended potential nursing/distribution hub of pathogenic strains applying science mapping review tools. Using the Preferred-Reporting-Items-for-Systematic-Reviews-and-Meta-Analyses (PRISMA) major scientific databases (Scopus Web of Science and PubMed) were searched for required and related data on astro-cosmic studies. A 7-decadal evaluation of authors' published documents using the non-parametric ANOVA test (Kruskal-Wallis H test) and Lotka’s model was applied. Among the three searched databases Web of Science ranked least in retrieved documents (130) followed by PubMed (331) and Scopus (409) with total documents retrieved as 693 between 1954-2023. Further results revealed that production/publication distribution was significant only in the first decade using Lotk’s model with an annual growth rate of 5.23%. It was also observed that more than 40 topics of interest/conceptual thematic were trending in association with astro-microbiological studies.
A focus on these topics and their associated themes possess the potential for understanding the future position of the microbes in outer space the distribution of potentially pathogenic strains from outer space and necessitates global interest for such studies.
Classical Stark and Zeeman Effects of Axially-symmetric Circular Rydberg States of He and He-like Ions
Circular Rydberg States (CRS) were studied theoretically and experimentally in numerous works. In particular in the previous paper by one of us there were derived analytical expressions for the energy of classical CRS in collinear electric (F) and magnetic (B) fields of arbitrary strengths imposed on a hydrogenic system (atom or ion). For the magnetic field B of any strength the author of that study gave formulas for the dependency of the classical ionization threshold Fc(B) and the energy at this threshold Ec(B). He also analyzed the stability of the motion by going beyond the CRS. In addition for two important particular cases previously studied in the literature – classical CRS in a magnetic field only and classical CRS in an electric field only – some new results were also presented in that paper especially concerning the Stark effect.
In the present paper we study analytically axially-symmetric CRS of a heliumic system (He atom or He-like ion) subjected to an electric or magnetic field of arbitrary strength.
In this investigation analytical techniques were applied.
We showed that in the case of the Stark effect the difference in the unperturbed structure of the heliumic systems (compared to hydrogenic systems) i.e. the non-negligible size causes the decrease of the classical ionization threshold as well as increases the energy and the orbit radius of the outer electron at the ionization threshold. Also the allowance for the non-negligible size of the internal subsystem increases the maximum possible absolute value of the induced electric dipole moment. In the case of the Zeeman effect we demonstrated that the non-negligible size of the inner system increases the energy and the orbit radius of the outer electron.
The allowance for the non-negligible size of the internal subsystem can strongly affect the properties of the axially symmetric circular states. We believe that our results are of fundamental importance.
Quantum Gravity without Quantization
An alternative way to construct a quantum model of gravity is described in this paper not by quantizing the classical model but by introducing a graviton background which has a low temperature but strongly interacts with any particle.
Gravity in this case is the effect of screening the background of gravitons by bodies; several additional effects appear when photons or bodies move through the background.
Using Planck's formula for the graviton spectrum and taking into account the pairing effect for some of the gravitons Newton's constant can be calculated and the magnitudes of the additional effects can be estimated.
These small additional effects can be important for cosmology since they allow to describe the results of cosmological observations without dark energy.
Developing a New Method for the Estimation of Valsartan (VST) in Pharmaceutical Dosage Samples by Using Diazotization and Coupling Reactions Spectrophotometrically
A new method for valsartan (VST) estimation in pharmaceutical dosage samples by spectrophotometry was developed.
The method was based on the formation of coloured dye by the diazotization reaction of 3-amino-2-naphthol with sodium nitrite in an acidic medium to form diazonium compounds which were then coupled with VST in a basic medium.
The drug sample showed linearity in the range 4.6 - 24.2 μgmL-1 and the λmax was found at 432nm. Sandell’s sensitivity (9.950×10-3) Molar absorbtivity (Ɛ= 4.377×104) regression equation (y= 0.0775x + 0.0041) correlation coefficient (r2= 0.968) detection limit (DL= 0.668) and quantitation limit (QL= 2.024) were evaluated.
The percentage recovery of the drug samples was found to be 100%. This method successfully determined VST in Pharmaceutical dosage samples.
Review on Intrinsic Shape of Elliptical Galaxies
Elliptical galaxies as one of the fundamental types of galaxies have attracted astronomers due to their intriguing properties. In this review we explore the intrinsic shape of elliptical galaxies a field that plays a pivotal role in understanding their formation evolution and interactions within the cosmos. Methods for intrinsic shape determination using photometric and kinematic methods are extensively discussed. The use of photometric data and surface brightness profiles to derive the intrinsic shapes of elliptical galaxies is examined and triaxial models are reviewed. Constraining the intrinsic shapes of elliptical galaxies is crucial to understanding their formation histories. Elliptical galaxies are characterized by their ellipsoidal rather than disk-like shapes and understanding the underlying factors and their intrinsic shapes of elliptical galaxies determination provides valuable insights into their formation evolution and the broader context of galaxy morphology. One key aspect of studying the intrinsic shape of elliptical galaxies involves the analysis of their axial ratios which describe the flattening of the galaxy along different axes. The axial ratio is defined as the ratio of the semi-minor axis to the semi-major axis of the ellipse representing the galaxy's cross-section. The intrinsic shape can vary from nearly spherical (axial ratio close to 1) to highly elongated (axial ratio significantly different from 1).
Synthesis of Optimal Control of Spacecraft Angular Momentum for Spatial Turn Taking into Account Energy Costs Using Quaternions
In this paper we propose solving the specific original problem of control synthesis of spacecraft attitude. Optimization of the control program is made with the use of a new criterion of quality that combines energy costs and duration of reorientation under restrictions on control (the presence of a time factor limits the duration of slew maneuver).
The construction of optimal control for angular momentum change is based on the quaternion method and L.S. Pontryagin maximum principle. An analytical solution to the problem was obtained on the base of a differential equation relating the orientation quaternion and angular momentum of a spacecraft.
Key properties of the optimal solution are formulated in analytical form; the features of optimal motion are studied in detail. The control law is formulated in the form of explicit dependence between control and phase variables. In a case when the controlling torque is limited by the given restriction (at the beginning and end of a turn) analytical formulas have been written for the duration of braking and acceleration. Main relations which determine optimal values of parameters of the algorithm for control of angular momentum are given. Examples and results of mathematical modeling of spacecraft motion formed by optimal control were given. This data in addition to the theoretical descriptions illustrates the process of reorientation in evident form and demonstrates the practical feasibility of a designed method for control of angular momentum during spatial turn.
The designed optimal algorithm of control of spacecraft motion improves the efficiency of spacecraft attitude system and originates more economical performance of spacecraft during flight on orbit.
Laboratory Analogs of Thermally Processed Ices Containing H2O, N2, NH3, CO2, and C2H3N Relevant to Astrophysical Environments
Laboratory simulations can benefit ground- and space-based observations of icy bodies in outer space. It is well-known that NH3 and CO2 can interact forming ammonium carbamate (CH6N2O2).
This study examines NH3 and CO2 in thermally processed H2O-rich ices in the laboratory via mid-infrared absorption spectroscopy. In particular the presence of CO2 in NH3-ice mixtures thermally annealed at 150 K for more than four hours in systematic experiments suggested that ammonium carbamate could potentially trap volatiles within the ice matrix.
Additional studies with acetonitrile (C2H3N) in ice mixtures containing H2O CO2 and NH3 were also performed. Absorption peak position changes were recorded when the temperature was slowly increased (≤ 5K/min) and also annealed at temperatures up to 150 K.
These studies will hopefully be useful in interpreting pre-biotic chemistry in the Solar System.
Tailoring Ti3C2Tx MXene Flake Sizes for Modified Electrochemical Performance: A Top-down Approach
Two-dimensional (2D) materials such as MXene (Ti3C2Tx) have garnered extensive attention in recent years due to their exceptional performance across various domains. The flake size of Ti3C2Tx notably influences its specific surface area a pivotal factor in interfacial interactions within electrochemistry.
Presently modifying the flake size of bulk Ti3C2Tx typically involves complex and costly processes like ultrasonic treatment and isolation. Leveraging the specific preparation principle of MXenes which involves etching the A layers in precursor MAX phases a top-down strategy for producing Ti3C2Tx flakes of desired sizes has been proposed in this work. In this approach precursor Ti3AlC2 particles undergo ball-milling to adjust their size.
Through this innovative strategy dispersions of Ti3C2Tx flakes with varying average lateral sizes are generated enabling an investigation into the impact of lateral size on the electrochemical properties of Ti3C2Tx flakes. By controlling the ball milling time for Ti3AlC2 powders the resulting average sizes of Ti3C2Tx (0 2 4) are 6.34 μm 2.16 μm and 0.96 μm respectively. Particularly the Ti3C2Tx (2) electrode composed of 2.16 μm sheets demonstrates remarkable performance metrics. It exhibits a high areal capacitance of 845.0 mF/cm2 at a scan rate of 5 mV/s along with a gravimetric capacitance of 244.0 F/g at a current density of 1 A/g.
This study presents a facile method to enable mass production of Ti3C2Tx with sheets of varying sizes addressing both small and large dimensions.
High-power Microwaves Against Locust Invasion
There are a lot of phytophagous and harmful animals in agriculture and forestry in the entire world. The ultimate goal in locust control is the use of preventive and proactive methods that disrupt the environment to the least possible extent. This would make agricultural production easier and more secure in the many regions where growing crops is of vital importance.
The possibility of using high-power microwave systems to combat harmful animal pests in agriculture and forestry is discussed. The proposed method is compared favorably with respect to the environment.
The obtained results of the study demonstrated the possibility of using modern sources of high-power microwave radiation to solve the problem of insect invasion.
It should be noted that the use of powerful microwaves is a promising means of controlling locusts and other pests. Mobile international forces equipped with modern microwave apparatus can solve the problem of combating locusts and other pests on a global scale without harming the environment. Microwave systems can also be used against other phytophagous pests of agriculture and forestry.
Sputtering Heterogeneous Tungsten Carbide Targets by Light Ions Bombardment
This paper presents a model for sputtering heterogeneous two-component materials with light ions.
The model based on two sputtering mechanisms makes it possible to calculate the total sputtering coefficients of the target components and it is easily transformed for the case of sputtering different types of targets. Model testing was conducted for the case of sputtering homogeneous tungsten carbide targets with ions of different energies.
The results of the calculations are given in comparison with experimental data and the results of computer simulation. The comparison shows good agreement of the calculated values with the data of other authors. The proposed model was used to describe stationary (stoichiometric) sputtering of tungsten carbide targets. Using this model the concentrations of components in the modified target layer were calculated and the thickness of the modified layer was also estimated.
The method of calculating the concentration of target components in the modified layer and the thickness of this layer can be the basis of the technology of creating materials with given properties of the surface layer.
A Statistical-based Stability-Indicating Assay for the Estimation of Salbutamol and Ketotifen using HPLC and HPTLC Methods
There are very few methods for simultaneously determining a combined dose of SAL and KET.
The current study aims to explore accurate precise simple and cost-effective HPLC and HPTLC techniques for the simultaneous assessment of Salbutamol (SAL) and Ketotifen (KET).
The determination of Salbutamol and Ketotifen was performed by HPLC and HPTLC methods using 280 nm and 258 nm as the determination wavelength respectively. Methanol was used to dissolve the drug for estimation in HPLC using mobile phase methanol: 10mM di-Potassium hydrogen orthophosphate in the ratio of 55:45 v/v of pH 4 at a flow rate of 1mL/min and in chloroform: toluene: methanol (7: 2: 3 v/v/v) for the estimation in HPTLC. Moreover a statistical comparison was made between the results obtained through HPLC and HPTLC of Salbutamol (SAL) and Ketotifen (KET) using the Student’s t-test and F-test.
A linear response was observed in the range of 4-24 µg/mL and 2-12 µg/mL respectively for SAL and KET for HPLC. R2 was found to be 0.9998 and 0.9999 respectively. For HPTLC the linear response was observed in the concentration range of 20-120 ng/ spot and 10 - 60 ng/ spot for SAL and KET respectively. R2 was found to be 0.9988 and 0.9998 respectively. The limit of detection (LOD) for HPLC was estimated as 0.34 µg/ml and 0.10 µg/ml for SAL and KET respectively and for the HPTLC method the LOD was estimated as 4.8 µg/ml and 1.5 µg/ml respectively. Analysing the marketed formulation by using both methods SAL and KET within the range of 100 ± 2% were recovered. The results obtained after the estimation of the Mastifen S tablet by applying both methods were according to nominal content. Degradation studies were performed using both methods. It was found that Salbutamol was unstable in hydrolytic oxidative and thermal degradation whereas stable in photolytic conditions. Ketotifen was found to be stable in thermal and photolytic conditions and unstable in hydrolytic and oxidative conditions.
The proposed stability indicating HPLC and HPTLC methods for SAL and KET was found to be simple accurate and reproducible for quantitative estimation in pharmaceutical dosage form without interference from the excipients or degradation products from the main drug component.
Standardization and Evaluation of Triphala Juice and Quantification of Gallic Acid as a Biomarker by Analytical Techniques
Standardization of Triphala Juice was performed by using the WHO Guidelines. The Parameters included Preliminary Analysis Phytochemical Identification Heavy Metal Estimation etc. A new simple specific precise and accurate UV Spectrophotometric High-Performance Liquid.
Chromatography and High-Performance Thin Layer Chromatography method has been developed for the Estimation of Gallic Acid in pure form.
The UV- Spectrophotometric method was developed using Schimadzu 1800 UV - Visible spectrophotometer using methanol as a solvent. The method was shown to be linear with a detection wavelength of 273 nm for Gallic Acid.
The separation was achieved on the Schimadzu Prominence-I RP-HPLC and the column used was C18 column using mobile phase consisting of mixture of Methanol: 0.1% OPA (50:50). The detection was carried out at 280 nm with a flow rate of 0.7 ml/min. The retention time for Gallic Acid was found 3.89 minutes. The calibration curve was found linear (r2 = 0.999) for RP- HPLC method.
The HPTLC method was developed using Aetron Sprayline instrument Methanol as solvent and mobile phase consisting of Toluene: Ethyl Acetate: Formic Acid: Methanol (3:3:0.9:0.2). The method was found linear and the wavelength of detection for Gallic Acid was 254 nm respectively.
The percentage recoveries for both methods were found in the 98.0- 102.0% range.
The methods were validated in accordance with International Conference on harmonization acceptance criteria for specificity linearity precision accuracy robustness and system suitability. The excipients did not interfere in the determination of Gallic acid in Triphala Juice.
The suggested approach was effectively implemented for the quantitative determination of gallic acid in Triphala juice which would aid in quality control.
Advancements of Lanthanide-doped Phosphors in Solid-state Lighting Applications
The challenge of energy conversion and enhancement has been a problem in the world of lighting technologies as the population and global industrialization grow rapidly. Solid-state lighting (SSL) has proven to be a better alternative in the illumination industry because of its environmentally friendly and high energy efficiency. Lanthanide-doped phosphors have gained global attention in SSL because they have versatile applications with enhanced overall performance and luminescence. This review delves into the advancement in lanthanide-doped phosphors for Solid-state lighting (SSL) applications. It discusses the in-depth analysis of how to tailor the crystal lattice design optimize the host material for emission efficiency and minimize the non-radiative pathways. This paper further discusses the lanthanide-doped phosphor composition strategies to obtain desired emission spectra and enhanced color rendering index with the Energy transfer mechanism and the synthesis techniques. This review also addresses 3 processes for expanding the light spectrum current challenges future directions and emerging trends present in the lanthanide-doped phosphor in Solid-state lighting (SSL) applications.
Understanding the Origins of Quark Charges, Quantum of Magnetic Flux, Planck’s Radiation Constant and Celestial Magnetic Moments with the 4G Model of Nuclear Charge
In our previous published papers considering 3 large atomic gravitational constants assumed to be associated with weak strong and electromagnetic interactions we have proposed the existence of a nuclear charge of magnitude en=2.95e and developed a nuclear mass formula associated with strong and weak interactions having 4 simple terms and only one energy coefficient.
Two important assumptions are that there exists a weak fermion of rest energy 585 GeV and strong coupling constant is the squared ratio of electromagnetic charge and nuclear charge. The aim of this paper is associated with understanding the mystery of the quantum of magnetic flux Planck’s quantum radiation constant and Reduced Planck’s constant. Proceeding further quark charges strong coupling constant nuclear stability nuclear binding energy medium and heavy atomic X-ray levels and celestial magnetic moments can be understood in a unified approach. It may also be noted that by considering the integral nature of elementary particle masses it seems possible to understand the discreteness of angular momentum.
Considering our proposed en=2.95e=3e as a characteristic nuclear charge it seems possible to understand the integral nature of quarks electromagnetic charge. With this idea neutron proton and pion decay can be understood very easily.
In all the cases the up quark of charge (±2e) seems to play a crucial role in the internal transformation of the down quark of charge (±e) and external observable elementary basic elementary particles. It needs further study at the fundamental level. Proceeding further quantum of magnetic flux Planck’s radiation constant and Reduced Planck’s constant can be understood with our 4G model of final unification.
Advanced Gyrotron Concepts for Spectroscopic Applications
Currently some modern spectroscopic applications require sub-terahertz and terahertz continuous-wave electromagnetic radiation sources with power levels from 0.1 to 100 W. Gyrotron a powerful high-frequency vacuum electronics device is considered one of the promising sources for these aims.
Modification of the gyrotron design promotes the widespread use of these devices for DNP/NMR spectroscopy.
Promising non-canonical concepts are presented the features of which compare favorably with the classical gyrotron scheme.
The gyrotron concepts we considered allow us to master the terahertz range and develop a unique gyrotron installation for each scientific group considering the specifics of their scientific research.
Measurement of Viscoelastic Properties by Free Loading-Mass Method
A procedure for determining the elastic and viscous properties of the sample material on the basis of the forced vibrations of a sample of mass loaded with a certain mass is developed. One of advantages of using the top mass instead of a rigid fixation is the appearance of an additional deformation resonance the frequency of which is times smaller than the resonance frequency of the fixed sample.
The experimental setup implementing the free mass method is described. Notably the proposed scheme does not require any adjustment and is assembled from standard devices. By changing the design of the sample only both shear and compression-tension strains can be measured. The combination of these methods allows measuring the complex Poisson’s ratio in addition to modulus of elasticity and loss factor.
One-dimensional (1D) and two-dimensional (2D) models of specimen deformation are considered. For the 1D deformation model approximate formulas for calculating the modulus of elasticity and the loss factor are substantiated and the limits of validity these formulas are outlined. Improving the accuracy of measurements is also considered. To do this it is necessary to fully describe the boundary conditions on the deformable sample. The developed 2D model of sample deformation made it possible to calculate the elastic modulus form factors for various samples with axial symmetry.
The method may become a Standard for measuring viscoelastic properties of materials (complex elastic and shear modulus as well as complex Poisson's ratio).
NiO@PANI based Nanocomposites as an Advanced Functional Material: Experimental and Computational Approach
Individually metal nanoparticles (NPs) and conducting polymers show unique properties due to small size large surface area and high order of conductivity. But their combination may result in a synergistic effect in properties.
The NiO NPs and conducting polymer Polyaniline were prepared by modified Sol-gel and chemical oxidative methods respectively. Powder XRD FTIR TEM and UV-visible methods were used for the structural evaluation. The computational (DFT) study was performed to support experimental results. The NiO/Polyaniline (PANI) nanocomposites (NCs) were explored as corrosion inhibitors electrical conductors and photocatalytic agents.
The NiO/Polyaniline NCs showed 91.52% corrosion inhibition efficiency at 1000 ppm concentration. The photocatalytic activity was investigated against methylene blue dye under ultraviolet light. The NiO/Polyaniline NCs decompose 90% of organic dye. The NCs exhibit good conducting corrosion inhibition and photocatalytic activity.
The metal oxide (NiO NPs) and PANI-based NCs can be used as corrosion inhibitors conducting material and for the degradation of organic compounds (dyes) in impure water.