Solutions Of Various Concentrations Research Articles

Design of Bridge Type C-Band Planar RF Sensor for Detection of Solute Concentration Level in Water

In this paper, a planar Micro-strip-based bridge topology CSRR is proposed for the detection of various solute concentrations in water sample. The designed bridge topology CSRR (B-CSRR) sensors resonates at 5.18 GHz with a Q-factor of 170, which exhibits a fractional sensitivity (10.17%). To avoid the contamination of test liquids, use of the thin Teflon layer is incorporated on top of the sensor region. The numerical analysis of the sensors for various scenarios including the sensor loaded with several lossy samples are carried out and accordingly shift in resonant frequency is recorded. The optimized design topology helps to attain better electric field confinement at the resonant frequency, which eventually leads to improved dielectric sensitivity. In the next part, an equivalent circuit of the proposed sensor is developed using the Advanced Design System (ADS) software. Afterwards, the designed sensor is fabricated on 0.8mm thick Taconic TLY-5 substrate ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\boldsymbol {\varepsilon }_{r}$ </tex-math></inline-formula> = 2.2). Finally, the measurement of B-CSRR sensor is carried out for different solute concentration in pure water, which is in present scenario are salt and detergent concentration, respectively. The developed sensor is found to be quite sensitive which produces a substantial change in the measured insertion loss even for small variation in solute concentration. For instance, a typical 2% variation in detergent, and salt concentration leads to nearly 1.5 dB, and 2.0 dB, change in measured S21.

THE INFLUENCE OF THE SALTITY OF THE MOISTURIZING SOLUTION ON THE DIELECTRIC PERMEABILITY OF CLAYS IN THE FREQUENCY RANGE FROM 1 MHZ TO 8 GHZ

The article presents the results of measurements of the complex dielectric constant of clays saturated with NaCl solution of various concentrations in a wide frequency range. The measurements were carried out at positive temperatures. It was revealed that several relaxation processes are observed in the spectra. A model is proposed that makes it possible to take into account the relaxation processes and their dependence on the concentration of the salt solution. The concentration practically does not affect the parameters of the processes, in contrast to the temperature.

Study and analysis of nonlinear (2+1)-dimensional solute transport equation in porous media

In the present endeavour, the shifted Legendre collocation method is extended to obtain the solution of nonlinear fractional order (2+1)-dimensional advection–reaction–diffusion solute transport equation. The variations of solute concentration of the model for different fractional order space and time derivatives are presented graphically for various particular cases. The main feature of the present contribution is the graphical exhibitions of the effects of advection term, reaction term and fractional-order parameters on the solution profile. To authenticate the effectiveness of the method, a drive has been taken to compare the obtained results with the existing analytical results of the integer-order form of the considered model through error analysis which are displayed in tabular and pictorial forms.

Physiological and Disease Models of Respiratory System Based on Organ-on-a-Chip Technology.

The pathogenesis of respiratory diseases is complex, and its occurrence and development also involve a series of pathological processes. The present research methods are have difficulty simulating the natural developing state of the disease in the body, and the results cannot reflect the real growth state and function in vivo. The development of microfluidic chip technology provides a technical platform for better research on respiratory diseases. The size of its microchannel can be similar to the space for cell growth in vivo. In addition, organ-on-a-chip can achieve long-term co-cultivation of multiple cells and produce precisely controllable fluid shear force, periodically changing mechanical force, and perfusate with varying solute concentration gradient. To sum up, the chip can be used to analyze the specific pathophysiological changes of organs meticulously, and it is widely used in scientific research on respiratory diseases. The focus of this review is to describe and discuss current studies of artificial respiratory systems based on organ-on-a-chip technology and to summarize their applications in the real world.

Influence of acid activation on the NH3-adsorption properties of a Turkish bentonite

AbstractIn this study, the adsorption of NH3 gas on a bentonite from Ünye (Turkey) in its natural state and after acid treatments, was investigated experimentally at 298 K and up to 100 kPa. Bentonite was treated with HCl solutions of various concentrations (0.5–2.5 M) at 75°C for 4 h. X-ray diffraction (XRD), X-ray fluorescence (XRF), N2 adsorption and thermogravimetric/differential thermal analysis (TG/DTA) were used to characterize the bentonite before and after acid treatment. The quantitative XRD analysis demonstrated that the bentonite sample was composed predominantly of smectite (75%), with abundant feldspar (20%) and minor opal-CT, analcime and quartz (5%). Increasing gas adsorption values of acid-treated bentonites were analysed depending on the structural changes of the clay. The NH3-adsorption capacities of the bentonite samples (3.801–5.068 mmol g–1) were also compared with previously studied clay-based materials (0.828–4.000 mmol g–1) in terms of their textural and structural differences.

A Multiscale Approach to Timescale Analysis: Isolating Diel Signals from Solute Concentration Time Series.

Solute concentration time series reflect hydrological and biological drivers through various frequencies, phases, and amplitudes of change. Untangling these signals facilitates the understanding of dynamic ecosystem conditions and transient water quality issues. A case in point is the inference of biogeochemical processes from diel solute concentration variations. This analysis requires approaches capable of isolating subtle diel signals from background variability at other scales. Conventional time series analyses typically assume stationary or deterministic background variability; however, most rivers do not respect such niceties. We developed a time-series filtering method that uses empirical mode decomposition to decompose a measured solute concentration time series into intrinsic mode frequencies. Based on externally supplied mechanistic knowledge, we then filter these modes by periodicity, phase, and coherence with neighboring days. This method is tested on three synthetic series that incorporate environmental variability and sensor noise and on a year of 15 min sampled concentration time series from three hydrologically and ecologically distinct rivers in the eastern United States. The proposed method successfully isolated signals in the measured data sets that corresponded with variability in gross primary productivity. The strength the diel signal isolated through this method was smaller compared to the true signal in the synthetic series; however, uncertainty analysis showed that the process-model-based estimates derived from these signals were similar to other inference methods. This signal decomposition method retains information that can be used for further process modeling while making different assumptions about the data than Fourier and wavelet analyses.

Ir0.11Fe0.25O0.64 as a highly efficient electrode for electrochlorination in dilute chloride solutions

Dimensionally stable anodes (DSAs) are regarded to be optimized electrodes for electrochlorination owing to their excellent electrocatalytic activity for the chlorine evolution reaction (CER). However, in dilute chloride solutions, DSAs preferentially produce oxygen rather than chlorine because of their low overpotential for oxygen evolution reaction (OER). Considering the frequent use of electrochlorination in dilute conditions, the poor efficiency of DSAs severely limits their environmental and industrial applications. Therefore, the aim of this study is to improve the CER efficiency of IrO2 in dilute chloride solutions with the addition of Fe2O3 as a co-catalyst which has a slow reaction rate of OER. In a dilute chloride solution of 1 mM NaCl, Ir0.11Fe0.25O0.64 showed a far higher current efficiency for CER (28%) than that of IrO2 (3%). Ir0.11Fe0.25O0.64 also exhibited better current efficiency in NaCl solution of various concentrations (1 mM to 2 M) than that of IrO2. This is attributed to the synergistic effect of Fe2O3 (slow OER rate) and IrO2 (fast CER rate). Moreover, the long-term stability of Ir0.11Fe0.25O0.64 was demonstrated with tap water electrolysis for 50 days. These results suggest that Ir0.11Fe0.25O0.64 has great potential to expand the scope of application of the electrochlorination system, particularly in dilute solutions.

β-Cyclodextrin functionalized rGO films for lead sensing

Graphene based materials have become the materials of choice for sensing applications due to their large surface area, high electrical conductivity and their ability to interact with various chemical species. Heavy metals bind with proteins and pose a potential risk to human life when exposed to higher concentrations. Thus, precise and quick detection of heavy metals is essential. Here, we report the use of β-cyclodextrin (BCD) functionalized reduced graphene oxide (rGO) as a chemiresistive sensor material, for heavy metals sensing in aqueous medium. Functionalization of rGO led to selectivity towards lead detection. Significant change in resistivity was observed within 15 min when the BCD functionalized rGO film was exposed to Pb(NO3)2 solution of various concentrations. A chemiresistive device was fabricated and characterized. The development of simple and selective chemiresistive sensors is expected to provide a facile solution for heavy metal detection such as lead for point of use sensing devices.

Application of fluorescent dextrans to the brain surface under constant pressure reveals AQP4-independent solute uptake.

Extracellular solutes in the central nervous system are exchanged between the interstitial fluid, the perivascular compartment, and the cerebrospinal fluid (CSF). The "glymphatic" mechanism proposes that the astrocyte water channel aquaporin-4 (AQP4) is a major determinant of solute transport between the CSF and the interstitial space; however, this is controversial in part because of wide variance in experimental data on interstitial uptake of cisternally injected solutes. Here, we investigated the determinants of solute uptake in brain parenchyma following cisternal injection and reexamined the role of AQP4 using a novel constant-pressure method. In mice, increased cisternal injection rate, which modestly increased intracranial pressure, remarkably increased solute dispersion in the subarachnoid space and uptake in the cortical perivascular compartment. To investigate the role of AQP4 in the absence of confounding variations in pressure and CSF solute concentration over time and space, solutes were applied directly onto the brain surface after durotomy under constant external pressure. Pressure elevation increased solute penetration into the perivascular compartment but had little effect on parenchymal solute uptake. Solute penetration and uptake did not differ significantly between wild-type and AQP4 knockout mice. Our results offer an explanation for the variability in cisternal injection studies and indicate AQP4-independent solute transfer from the CSF to the interstitial space in mouse brain.

A theoretical model for the hydraulic conductivity of montmorillonite in relation to the concentration and valence of electrolyte cations in solution

This study is among the first to report on a theoretical relationship linking the hydraulic conductivity of soil and aquifer with environmental solution conditions. A mathematical model is developed for predicting the hydraulic conductivity of montmorillonite from the concentration and valence of electrolyte cations in solution. The model relies on the diffuse double layer and DLVO theories, the aggregation kinetics, and the Hazen equation, with a few plausible assumptions, for establishing three individual relationships, with each corresponding to one of three steps in the cation-to-particle-to-grain-to-hydraulic conductivity pathway. It is based on a mechanistic understanding that the concentration and valence of electrolyte cations controls the size of montmorillonite primary particles by influencing the electrical double layer, subsequently regulates the grain-size distribution of montmorillonite via inter-particle collision, and finally determines the hydraulic conductivity of montmorillonite. The model is validated by direct measurements of the surface charge density, the grain-size distribution and the hydraulic conductivity of montmorillonite in NaCl and CaCl2 solutions of various concentrations. The theoretical model of predicting hydraulic conductivity developed here is novel for implementing more accurate modeling of contaminant transport in the environment with advantage of cost-savings.

Mesoscale Defect Motion in Binary Systems: Effects of Compositional Strain and Cottrell Atmospheres.

The velocity of dislocations is derived analytically to incorporate and predict the intriguing effects induced by the preferential solute segregation and Cottrell atmospheres in both two-dimensional and three-dimensional binary systems of various crystalline symmetries. The corresponding mesoscopic description of defect dynamics is constructed through the amplitude formulation of the phase-field crystal model, which has been shown to accurately capture elasticity and plasticity in a wide variety of systems. Modifications of the Peach-Koehler force as a result of solute concentration variations and compositional stresses are presented, leading to interesting new predictions of defect motion due to effects of Cottrell atmospheres. These include the deflection of dislocation glide paths, the variation of climb speed and direction, and the change or prevention of defect annihilation, all of which play an important role in determining the fundamental behaviors of complex defect network and dynamics. The analytic results are verified by numerical simulations.

Development of a new method for isolation of urban air particulates deposited in the human lung tissue

Particulate matters (PMs) are important pollutants in urban air pollution because of their variable composition. The pulmonary clearance of PMs is critical to prevent long-term immunological responses. This study established a new method for the isolation of probably deposited urban air particulates from the human lung tissue, to investigate the features of uncleared particulates. The lung samples were acellularized with SDS solution of various concentrations ranging from 1 to 10%to lyse cells and release the PMs. In addition, the extracellular matrix (ECM) that remained was digested by proteinase K enzyme. The results of this study demonstrated that an SDS solution of 4% is the optimum concentration for the isolation of settled PMs from the lung tissue. Moreover, the used enzymatic method could separate settled PMs from the lung ECM appropriately. The results exhibited that epithelial cells form 46% of the samples’ weight on average, whereas just 20% of isolated PMs were found in this part of the tissue. Both groups of separated PMs tend to agglomerate, but it is significantly higher in cellular isolated PMs. The particles separated from ECM have an agglomeration tendency, which is observable only by FE-SEM imaging. Moreover, we found a major part of urban air PMs deposited in ECM. The established method in this study can be used in future investigations to isolate other types of PMs settled in the lung, such as occupationally inhaled carbonaceous particulates.

Synthesis and Characterization Superabsorbent Polymers Made of Starch, Acrylic Acid, Acrylamide, Poly(Vinyl Alcohol), 2-Hydroxyethyl Methacrylate, 2-Acrylamido-2-methylpropane Sulfonic Acid.

Three polymers with excellent absorption properties were synthesized by graft polymerization: soluble starch-g-poly(acrylic acid-co-2-hydroxyethyl methacrylate), poly(vinyl alcohol)/potato starch-g-poly(acrylic acid-co-acrylamide), poly(vinyl alcohol)/potato starch-g-poly(acrylic acid-co-acrylamide-co-2-acrylamido-2-methylpropane sulfonic acid). Ammonium persulfate and potassium persulfate were used as initiators, while N,N′-methylenebisacrylamide was used as the crosslinking agent. The molecular structure of potato and soluble starch grafted by synthetic polymers was characterized by means of Fourier Transform Infrared Spectroscopy (FTIR). The morphology of the resulting materials was studied using a scanning electron microscope (SEM). Thermal stability was tested by thermogravimetric measurements. The absorption properties of the obtained biopolymers were tested in deionized water, sodium chroma solutions of various concentrations and in buffer solutions of various pH.

Bio-inspired construction of ion conductive pathway in covalent organic framework membranes for efficient lithium extraction

Summary As the most sophisticated separation system, biological membranes have served as natural prototypes for the design of artificial membranes because they provide high permeability and solute selectivity, owing to the presence of specialized ion channels. However, developing stable and selective artificial ion channels remains a formidable challenge. Herein, we demonstrate the construction of lithium nanochannels in two-dimensional covalent organic frameworks (COFs) to create biomimetic membranes. Implanted lithiophilic oligoethers conferred specificity and facilitated Li+ diffusion along the pore pathway of the COF. The ion channel characteristics were indicated by reversal potential measurements, showing that the relative permeability decreased in the order Li+ > K+ > Na+ > Ca2+ > Mg2+. The Li+ transfer was enhanced, while other ions were obstructed, allowing for high selectivity and permeability. A Li+/Mg2+ separation factor of 64 was achieved, confirming high lithium affinity. This study may serve as a design principle to develop selective artificial membranes for effective ion separation.

The Efficiency of Pre-Sowing Seed Treatment with Trace Element Solutions

This article analyzes the results of four-year research which examined the effectiveness of pre-sowing treatment (soaking, spraying) of white cabbage seeds with trace element solutions of various concentrations. The research was conducted under laboratory conditions at the Agricultural Chemistry and Soil Science Department of Omsk State Agrarian University with a mid-season-ripening, medium-yielding and high-yielding variety of white cabbage (Sibiryachka 60) found in the Omsk region. 0.02%, 0.04% and 0.05% solutions of ZnSO4 ⋅ 7H2O and 0.01%, 0.02%, 0.03% and 0.05% solutions of H3BO3 were used in the experiment. The cabbage seeds were soaked in water (control) and in trace element solutions for 6-12-24 hours. The germination energy and germination capacity of the seeds, the zinc distribution, and the biometric indicators of the seedlings and of the cabbage transplant seedlings were determined. The optimal concentrations of the trace element solutions and the optimal duration of pre-sowing treatment were established, which stimulated the development of seedlings and increased seed germination by 5-9%. It was noted that, compared with the control, 2 times more plants reached the 6-leaf phase by the time of planting when transplant seedlings were treated with a boric acid solution in the optimal concentration, and 3.6 times more plants did when fertilized with zinc. Based on the results the following is recommended for implementation in production: soaking seeds in a 0.03% solution of Н3ВО3; soaking seeds in a 0.04% solution of ZnSO4; soaking time - 6 hours; a 1:2 ratio of seeds to the solution; and concentration of solutions per element for boron – 0.005% and zinc – 0.01%.&#x0D; Keywords: white cabbage, seeds, micro-fertilizers, pre-sowing treatment

A study on electrochemical oxidationof phenol for wastewater remediation

This era having been driven by the industrial revolution caused a major outbreak of pollutant quantity in water. Phenol is one of the most toxic chemicals and electrochemical oxidation is undoubtedly one of the attractive alternatives for the degradation of phenol available in wastewater. The present study aims at finding the best combination of operating parameters maximizing the phenol removal by electrochemical treatment of phenolic wastewater. Synthetically prepared phenol solution of various concentrations was electrochemically oxidized using a cylindrical flow cell. It was found that initial phenol concentration, time, current density, and salt concentration have a strong influence on the removal of phenol. Furthermore, based on the results obtained, a second-order regression model was proposed to predict the responses. Analysis of variance (ANOVA) result and the R2 value of the model shows that the model could very well predict the realistic situation. According to the prediction by the model, the best set of operating conditions giving the complete removal of phenol is Time: 9.27 min, Current density: 3.58 A/dm2, supporting Electrolyte concentration: 3.29 g/L, and Initial Concentration: 13.64 ppm.

Effect of Plasma Activated Water, Hydrogen Peroxide, and Nitrates on Lettuce Growth and Its Physiological Parameters

Cold plasma generated by atmospheric pressure air discharge is a source of various gaseous reactive oxygen and nitrogen species (RONS). When the plasma is generated in a contact with water, the RONS dissolve into water, change its chemical composition, while producing so-called plasma activated water (PAW). The PAW has the potential to be effectively used in various agricultural applications, as the long lived liquid RONS (H2O2, NO2−, NO3−) may act like signaling molecules in plant metabolism or serve as nutrients. We studied the effect of the PAW on lettuce plants and compared it with the effect of H2O2 and/or NO3− solutions of various concentrations to assess their role in the PAW. The PAW was generated from tap water by DC driven self-pulsing transient spark discharge. Pre-grown lettuce plants were cultivated in pots with soil and irrigated with the PAW or solutions of H2O2 and/or NO3−. After 5 weeks the growth parameters, number and quality of leaves, fresh and dry weight of plants, photosynthetic pigment (chlorophyll a + b) content, photosynthetic rate, and activity of antioxidant enzymes (superoxide dismutase, SOD) were evaluated. Lettuce plants irrigated with the PAW in comparison with chemically equivalent solution of H2O2 and NO3− had similar dry weight; however, the PAW induced higher photosynthetic pigment content, higher photosynthetic rate, and lower activity of SOD. The NO3− mainly contributed to the increase of dry weight, photosynthetic pigment content, photosynthetic rate, and overall better appearance of plants. The H2O2 contributed to an increase of dry weight and induced SOD activity. In general, H2O2 and NO3− in proper concentrations can stimulate plant growth and affect their physiological properties.

Study of variation of optical and physical properties of saline water solutions with temperature

Measurements of refractive index, ultrasonic velocity, density and viscosity of pure water, aqueous NaCl solutions of various concentrations, and sea water collected from Diu sea shore (Gujarat, India), were carried out at temperatures of 20°, 30° and 40 °C. To determine the ultrasonic velocity, density and viscosity; the ultrasonic interferometer, pycnometer and Oswald’s viscometer were used, respectively. For the measurement of refractive index of these solutions at various wavelengths, the LEDs (Light Emitting Diodes) emitting radiations of different wavelength were used along with the Abbes refractometer. Experimental values of refractive indices have been compared with the values calculated using an empirical equation given by McNeil (1977) and Matthus (1974) and are in good agreement with the literature values. Experimental values of ultrasonic velocity of different solutions agree very well with the values calculated using the empirical equation given by Medwin (1975). Acoustical parameters like acoustic impedance (Z), adiabatic compressibility (βa) and intermolecular free length (Lf), were obtained by using values of ultrasonic velocity and density.

Peculiarities of care for patients with coronavirus infection. Important safety issues for health care workers

Background. In case of coronavirus disease (COVID-19), contact persons include, but are not limited to, health care workers (HCW) and caregivers of COVID-19 patients. Personal protective equipment is required for HCW working with patients or individuals with suspected COVID-19. Correct sequence and the correct technique of putting them on is very important.&#x0D; Objective. To describe the safety measures for HCW in care of patients with COVID-19.&#x0D; Materials and methods. Analysis of literature sources on this topic.&#x0D; Results and discussion. Contaminated environmental surfaces take part in the contact route of transmission. To reduce the role of fomites in the transmission of the new SARS-CoV-2 coronavirus, special recommendations of the Ministry of Health on surface cleaning and disinfection have been developed. After cleaning, disinfectants must be used to reduce the viral load on the surface. These disinfectants are also effective against other pathogens that are important in health care settings. Such agents include ethanol 70-90 %, chlorine-based agents, and hydrogen peroxide &gt;0.5 %. The register of disinfectants of Ukraine contains more than 200 brands. The vast majority of them are represented by alcohol- and chlorine-containing solutions of various concentrations, colors and odors. The use of these solutions is limited to the torso and extremities. These solutions have a number of limitations and caveats in their use. For instance, in case of contact with mucous membranes, they have an irritating effect and require rinsing with plenty of water. Vapors of some of them should not be inhaled, so they should be used in well-ventilated areas or with protective equipment. Alcohol-based products should not be applied to damaged areas of the skin due to protein denaturation. The Food and Drug Administration (FDA) recommends to use the chlorine- and alcohol-based solutions with caution due to the lack of evidence of their safety. The decamethoxine-based solution Yusept (“Yuria-Pharm”) is intended for disinfection of hands and other parts of the body, including the face; for disinfection of HCW gloves and gloves in other places; for disinfection and pre-sterilization cleaning of all medical devices from various materials; for disinfection of hairdresser’s, manicure, pedicure and cosmetic accessories; for disinfection of rooms, furniture, patient care items, hygiene products, utensils, containers, sanitary equipment, rubber carpets; for current, final and preventive disinfection; for use in aerosol disinfection systems such as Yu-box and other disinfection systems. Proper hand washing technique is also an important preventive measure. The effectiveness of prevention of HCW infection during their professional duties depends on how serious the problem is taken by the management of the health care institution and the HCW, who work with infectious patients, themselves.&#x0D; Conclusions. 1. For HCW working with patients or persons with suspected COVID-19, the use of personal protective equipment is mandatory. 2. Contaminated surfaces take part in the implementation of the contact route of infections’ transmission. 3. The vast majority of disinfectant solutions are alcohol- and chlorine-containing ones, which have a number of limitations and precautions in use. 4. Yusept solution is intended for disinfection of hands and other parts of the body, including the face; for disinfection and pre-sterilization cleaning of all medical devices; for disinfection of rooms, furniture, patient care items; for use in aerosol disinfection systems.

Predicting high‐frequency variation in stream solute concentrations with water quality sensors and machine learning

AbstractStream solute monitoring has produced many insights into ecosystem and Earth system functions. Although new sensors have provided novel information about the fine‐scale temporal variation of some stream water solutes, we lack adequate sensor technology to gain the same insights for many other solutes. We used two machine learning algorithms – Support Vector Machine and Random Forest – to predict concentrations at 15‐min resolution for 10 solutes, of which eight lack specific sensors. The algorithms were trained with data from intensive stream sensing and manual stream sampling (weekly) for four full years in a hydrologic reference stream within the Hubbard Brook Experimental Forest in New Hampshire, USA. The Random Forest algorithm was slightly better at predicting solute concentrations than the Support Vector Machine algorithm (Nash‐Sutcliffe efficiencies ranged from 0.35 to 0.78 for Random Forest compared to 0.29 to 0.79 for Support Vector Machine). Solute predictions were most sensitive to the removal of fluorescent dissolved organic matter, pH and specific conductance as independent variables for both algorithms, and least sensitive to dissolved oxygen and turbidity. The predicted concentrations of calcium and monomeric aluminium were used to estimate catchment solute yield, which changed most dramatically for aluminium because it concentrates with stream discharge. These results show great promise for using a combined approach of stream sensing and intensive stream discrete sampling to build information about the high‐frequency variation of solutes for which an appropriate sensor or proxy is not available.