Saturation Method Research Articles

EXTRACTION-SPECTROPHOTOMETRIC STUDY OF THE SYSTEM NICKEL(II) – HALOGENASEMERCAPTOPHENOL -AMINOPHENOL - WATER – CHLOROFORM

Reaction of nickel with halogenazomercaptophenol (HAMP) {1-(5-fluoro-2-pyridylazo)-2-hydroxy4-mercaptophenol, 1-(5-chloro-2-pyridylazo)-2-hydroxy-4-mercaptophenol} in the presence aminophenols (AP): 2-(N,N-dimethylaminomethyl)-4-methylphenol, 2-(N,N-dimethylaminomethyl)-4-ethylphenol studied by the Extraction-Photometric method. A single extraction with chloroform yields 97.1–98.9% nickel (II) in the form of a mixed-ligand complex (MLC). The optimal acidity range, at which the optical density is maximum and constant, is at pHop. 3.3 – 7.8 (pH 2.0 – 9.8). Maximum optical density is achieved within 5-10 minutes. The optimal condition for the formation and extraction of these compounds is (1.10-2.35)×10-3 mol/l concentration of HAMP and (6.31-8.42) ×10-4 mol/l - AP. The molar absorption coefficients of Ni (II) complexes at λmax were calculated by the saturation method and amount to ε610–650 = (1.3-1.7) ×104 . MLC in the organic phase are in monomeric form (γ = 0.91-1.09). Newly developed methods for extractionphotometric determination of Ni (II) for use in the analysis of oil and petroleum products Baku.

ВЗАИМОСВЯЗЬ ВАРИАЦИЙ ГЕОМАГНИТНОГО ПОЛЯ И ФУНКЦИОНИРОВАНИЯ КАРДИОРЕСПИРАТОРНОЙ СИСТЕМЫ ЧЕЛОВЕКА В УСЛОВИЯХ ЗИМОВКИ НА АНТАРКТИЧЕСКОЙ СТАНЦИИ «ВОСТОК»

The paper presents the results of analysis of correlation between levels of geomagnetic disturbance and cardiorespiratory parameters measured in members of the 64th Russian Antarctic expedition. Analysis established a correlation between geomagnetic disturbance (K-index) and blood saturation with oxygen. Blood saturation determined using the K-index showed a statistically significant difference (p = 0.022) by the Kruskal-Wallis criterion. The greater is geomagnetic disturbance, the higher blood saturation with oxygen. Considering the similarity of extreme environments of polar explorers and cosmonauts, the method of blood oxygen saturation can be recommended for use in low-orbit missions in order to study how geomagnetic disturbances affect cosmonaut's organism.

Providing an Optimal Model for Enhancing Cognitive Flexibility Based on Mindfulness in Nurses

Background and Objective: The present study aimed to provide an optimal model for enhancing cognitive flexibility based on mindfulness in nurses. Methods and Materials: This research was applied in terms of purpose and mixed qualitative in terms of data type. The research method was based on thematic analysis by nature. The study population included articles, books, and journals related to mindfulness-based cognitive flexibility. The sample size consisted of 15 articles and books, selected according to the principle of saturation and purposive non-random sampling method. In the qualitative section, a protocol was designed, and data analysis was conducted using thematic analysis. Findings: Based on the results of the qualitative section, a mindfulness-based cognitive flexibility protocol was designed, and its validity was examined and confirmed by experts. The results showed that among the 45 existing indicators (items), 8 main components were identified. Conclusion: These components of mindfulness-based cognitive flexibility included cognitive restructuring, relaxation, perception of controllability, problem-solving skills, stress management, obstacle confrontation skills, self-care skills, and acceptance and change skills.

A Dynamic Event-Triggered Saturation Method for Nonlinear Estimation with Application to Drag-free Control Systems

A Dynamic Event-Triggered Saturation Method for Nonlinear Estimation with Application to Drag-free Control Systems

Vapor-liquid equilibrium measurements of ionic liquid [DEME][TFSI] with different hydrofluorocarbon refrigerants R152a, R32, and R143a

To overcome the shortages of traditional working pairs (LiBr/H2O and NH3/H2O) for absorption-refrigeration systems (ARSs), novel working pairs consisting of low global warming potential (GWP) hydrofluorocarbons difluoroethane (R152a) and difluoromethane (R32) plus low-viscosity ionic liquid N,N‑diethyl-2‑methoxy-N-methylethan-1-aminium bis((trifluoromethyl)sulfonyl)amide ([DEME][TFSI]) are studied. Firstly, solubilities of R152a and R32 in [DEME][TFSI] are measured by the isochoric saturation method in the temperature range of 293 K ∼ 343 K and pressure range of 0.14 MPa ∼ 1.664 MPa with the relative expanded uncertainty of 0.03. A high-GWP hydrofluorocarbon 1,1,1-trifluoroethane (R143a) is involved in the experiment for further comparison. The non-random two-liquid model is used to correlate the vapor-liquid equilibrium data with average absolute relative errors of 0.55 % (R152a), 0.58 % (R32), and 0.94 % (R143a), respectively. [DEME][TFSI] shows its low viscosity and good solubility of hydrofluorocarbons by contrast with conventional ionic liquids. A refrigerant solubility rank order in [DEME][TFSI]: R152a > trans-1,3,3,3-tetrafluoropropene (R1234ze(E)) > R32 > 2,3,3,3-tetrafluoro-1-propene (R1234yf) > R143a is obtained from the comparison. This work provides the possibility to apply low-GWP working pairs R152a/[DEME][TFSI] and R32/[DEME][TFSI] in ARSs.

The role of green energy stock market in forecasting China's crude oil market: An application of IIS approach and sparse regression models

This study investigates the effectiveness of sparse regression models with their diverse specifications and the impulse indicator saturation (IIS) method in forecasting crude oil prices and their returns in China. The empirical findings showed that the IIS approach and sparse regression models are more effective than the benchmark of the no-change model. The IIS approach consistently outperformed the competing models and produced reliable results in terms of both ROS2 statistics and success ratio, as it is invariant to window size and time horizon. The results suggest that sparse regression models exhibit a notable decline in accuracy compared to the IIS approach over the long horizon. However, the selection of window size in the rolling window method plays a crucial role. Meanwhile, the sparse regression models are quite sensitive to window size; with a long horizon forecast and a small window size, the accuracy of the results is far less than with a broader window size. In contrast, the IIS method provides quite accurate forecasts regardless of window size and time horizon. The elastic smoothly clipped absolute deviation (E-SCAD) and elastic minimax concave penalty (E-MCP) remained more successful across the sparse models, possibly as a result of the high correlation among the set of predictors.

Comprehensive solubility study and inter-molecular interactions on fenbendazole dissolved in some aqueous aprotic and protic co-solvent solutions

The isothermal shake-flask saturation method was used to experimentally determine the mole-fraction solubility of fenbendazole in three aqueous co-solvent blends of 1,4-dioxane/acetone/NMP encompassing the range of 283.15 to 328.15 K. The solubility of fenbendazole in various blended solvents ranks NMP + water (4.852 × 10−2) > 1,4-dioxane + water (14.81 × 10−4) > acetone + water (2.285 × 10−4) with composition of 1,4-dioxane (acetone or NMP) of 1 at 298.15 K. The solubility data rises monotonically with 1,4-dioxane/acetone/NMP concentration at the same temperature. X-ray power diffraction images show that no solvate production or crystal transition appeared throughout the studies. The solubility to solvent composition and temperature was satisfactorily associated by the modified van't Hoff-Jouyban-Acree, quantitative structure–property relationship, and Jouyban-Acree models with relative average deviations of no higher than 7.05 % and root-mean-square deviation of no higher than 1.225 × 10−3. In addition, the 1,4-dioxane/acetone/NMP + water blends studied in this paper and the methanol/ethanol/EG/DMF + water blends previously reported both used the extended Hildebrand solubility approach to quantitatively describe the solubility behavior at 298.15 K. The average relative deviations were kept under 4.06 % on both cases. As stated by the examination of the linear solvation energy relationship, the solubility parameter and dipolarity-polarizability of solutions have a significant influence on the solubility variation. The effective method of inverse Kirkwood-Buff integrals was used to investigate the preferred solvation of fenbendazole at 298.15 K. In blends with intermediate and rich ethanol/DMF/1,4-dioxane/acetone/NMP composition areas, the preferred solvation parameters of ethanol/DMF/1,4-dioxane/acetone/NMP displayed positive values, indicating the preferential solvation of fenbendazole by the co-solvents. Thermodynamic examination of the entropy-enthalpy compensation and dissolution parameters for fenbendazole dissolving in blends led to the identification of an enthalpy and/or entropy-driven mechanism as well as an endothermic process. Moreover, the average local ionization energy and electrostatic potential of molecular surface were utilized as effective instruments to demonstrate the microscopic electrostatic properties of acidity and basicity, respectively. The fenbendazole molecule's groups of –N in the five-membered ring and –NH in the straight chain serve as the main targets for electrophilic and nucleophilic assault. The weak interactions between fenbendazole and several solvents were shown using an independent gradient model based on Hirshfeld partition analysis.

Solubility measurements, correlation, and thermodynamic characterization of 4-guanidinobenzoic acid hydrochloride in pure and binary solvents from 294.55 K to 333.65 K

The solubility of 4-guanidinobenzoic acid hydrochloride (4-GABCL) in pure solvents (H2O, methanol, ethanol, n-propanol, isopropanol, 1-butanol, and 1-pentanol) and two binary solvents (H2O + ethanol/isopropanol) were determined by the dynamic saturation method in the temperature range of 294.55 K–333.65 K under atmospheric pressure. From the measurement results, it could be observed that the solubility of 4-GABCL in both pure and binary solvents all increased with increasing temperature. The solubility order of 4-GABCL in pure solvents was ranked as follows: methanol > H2O > n-propanol > ethanol > n-butanol > isopropanol > n-pentanol. The solubility of 4-GABCL in binary solvents tended to increase and then decrease with increasing molar fractions of ethanol and isopropanol, and the solubility of the solute in the binary solvents was greater than that of each in the monosolvents. In addition, Ideal model, Apelblat model, λh model, Wilson model, and NRTL model had been used to correlate the solubility of 4-GABCL in pure and binary solvents. Correlated effects show that the Wilson model gives the best correlation. The influence of solvents on the solubility of 4-GABCL was further studied by KAT-LSER model. The results showed that the solubility was mainly affected by the polarizability and the self-viscosity of the solvent.The mixing and dissolution thermodynamic properties of 4-GABCL in all experimental solvents had been calculated and analyzed by using the Wilson equation and solvent data. It was determined that the mixing and dissolution of 4-GABCL were spontaneous, endothermic and entropy-driven in the study systems. Besides, the solubility order of the pure solvent is consistent with the dissolution entropy at a temperature of 318.15 k.

Do markets Trump politics? Fossil and renewable market reactions to major political events

AbstractWe investigate the effects of three events with major importance for climate policy on energy sector stocks: the Paris Agreement, the Trump election and presidency, and the Biden election. By combining event studies with impulse‐indicator saturation methods, we show that the Paris Agreement and the election of Mr. Biden benefited renewable industries, while the election of Mr. Trump had negative effects. For fossil fuel industries, the effects were largely the opposite. Despite Trump's efforts to eliminate environmental regulations, his presidency did however witness a decrease in both US coal production and consumption, while natural gas and oil consumption increased.

Towards High Strength-Ductility Balance Using Double Annealing Cycles

Impact of first annealing on the formation and evolution of the microstructure during second annealing and on the final mechanical properties was investigated. Simple Fe-C-Mn-Si steel was used in this study. Dilatometry tests coupled with metallographic examinations were carried out to monitor the evolution of phase transformations and associated microstructure. Difference in the austenite evolution between simple and double annealing was highlighted. Based on the obtained results, conditions were selected for the annealing trials on bigger sample. Mechanical properties of heat-treated steels were assessed through the standard tensile tests. Double annealing treatment resulted in a better strength-ductility balance and in a good stability against soaking and quenching temperature variation. Complex ultra-fine multiphase microstructure containing at least 5 different microstructural constituents was revealed and observed using Scanning Electron Microscopy. As well, retained austenite fraction was estimated through magnetization saturation method.

Quench and Bainite (Q&B) Thermal Cycle as an Alternative to Standard Quench and Partitioning (Q&P) Annealing to Produce AHSS

In this work a new kind of thermal treatment, called Quenching and Bainite (Q&B), was proposed and studied. A rather standard Fe-C-Mn-Si composition was used for this study. Annealing trials were performed using a combination of salt pots on relatively big samples allowing to perform the standard tensile and hole expansion tests. The obtained results were compared with the properties obtained using more known Q&P annealing. Generated microstructures were also compared. Characterization was done using optical and Scanning Electron Microscopy as well as magnetization saturation method for measuring retained austenite fractions. The Q&B heat treatment provides an alternative way to obtain 3G AHSS with promising strength-ductility-formability compromise.

IMPROVING THE THERMAL STABILITY OF CARBON-CARBON COMPOSITE MATERIALS USING SELF-PROPAGATINGHIGH-TEMPERATURE SYNTHESIS

Abstract.This research focuses on the development of effective protective coatings for carbon-carbon composite materials (CCСM), which are important components in high-temperature processes in aerospace engineering. The application of CCСM is limited by their sensitivity to oxidation, erosion and burnout in gas streams. In light of these limitations, our work is aimed at creating protective coatings using the method of self-propagating high-temperature synthesis, which provide increased performance and extend the service life of composites. The main task of the research is to identify the optimal compositions of powders for chromium-doped protective coatings through the SHS process. Various methods of obtaining protective coatings were analyzed, including chemical-thermal methods and methods of saturation from the liquid phase, revealing the peculiarities of the interaction of coatings with the CCСM matrix and changes in their mechanical characteristics. In addition to the classical methods of obtaining coatings, the method of surface saturation from the solid phase in an active gas environment as part of the SHS process was investigated. This method provides high-quality coating surfaces, reduction of processing time and the possibility of reaching high temperatures, depending on the composition of the SHS mixture. An important element of the research is the analysis of modern publications and research in the field of protective coatings. Special attention is paid to the problems associated with chemical interaction with the matrix of CCСM and uneven formation of carbide phases along the cross-section of the material. Experimental studies include a factorial experiment to identify the compositions of powder mixtures that provide high wear resistance. Various independent variables, such as chromium, silicon, titanium and aluminum content, are considered for their effect on the physical and mechanical properties of the coatings. The study focuses on the optimization of the parameters of thermal autoinitiation of SHS mixtures under process conditions. The regression equation for evaluating the dependences of the wear resistance of coatings on auto-initiation parameters and the content of alloying elements is given. The analysis of the research results includes the construction of three-dimensional graphic dependencies to optimize the wear resistance of coatings in the Cr-Al-Ti and Cr-Al-Si systems. Chromoalumosilicization of the coating showed better wear resistance, exceeding the wear resistance of untreated samples by 2.6-3.2 times, which allows the use of this technology for parts of aerospace equipment. It is interesting that the porous surface of coatings obtained by the SHS method prevents the penetration of oxygen into the material, contributing to the formation of oxide protective membranes, such as SiO2, TiO2, Cr2O3, Al2O3.

Greenhouse environmental control target constrained by discrete surface curvature and multi-objective optimization algorithm

Protected greenhouse provides a suitable micro-environment for crop growth, which enhances the quality and yield of agricultural products. How to optimize the greenhouse environment is currently a pressing issue in protected agriculture. In this research, we propose a new environmental control method from the perspectives of crop photosynthesis rate and environmental control cost. The photosynthesis rate data are collected from a nested experiment of tomatoes, and these data are combined with the support vector regression algorithm to establish a photosynthesis rate model. The cost function of greenhouse environmental control is established by theoretical calculation. The non-dominated solution sets of photosynthesis rate and control cost are obtained through an improved non-dominated sorting genetic algorithm Ⅱ. To determine the optimal solution among the numerous Pareto solutions, the geometric characteristics of the photosynthetic response surface are considered to constrain the control target. Then, a discrete surface curvature method is proposed to computer the constraint region. The intersection between the Pareto solutions and the constraint region is regarded as the environmental control target. The validation experiment demonstrates that the proposed method can effectively enhance photosynthetic accumulation and reduce control cost. Compared to the traditional saturation method, this method achieves a 53% cost reduction while still obtaining 89% photosynthetic accumulation. Compared to the U-chord method, this method increases photosynthetic accumulation by 12% with only a 3% increase in cost. The research has important implications for protected agriculture production.

Numerical investigation of gas and sand production from hydrate-bearing sediments by incorporating sand migration based on IMPES method

Accurately predicting gas and sand production from oceanic gas hydrate reservoirs considering multi-field coupling effects is crucial. To address this, we first systematically summarized the multi-field coupling effect of gas hydrate-bearing sediments (GHBS) during sand production and gas production. After that, we developed a thermo-hydro-mechanical coupled model that incorporates both sand detachment and sand migration (THMS) to describe the complex behaviors of fluid and solid flow. We then solved this model using the implicit pressure-explicit saturation (IMPES) method and incremental scheme for a cylindrical core and presented a detailed algorithm derivation process for reproducibility. The newly developed model was validated through comparison with available experimental data. Subsequently, several parameter effects, including outlet pressure, initial hydrate saturation, load stress, and sand detachable ratio, on the behaviors of fluid and solid flow were studied. The computation results indicate that high sand production can be induced by low outlet pressure, high initial hydrate saturation, high load stress, and high sand detachable ratio. Meanwhile, high cumulative gas production can be caused by low outlet pressure, low initial hydrate saturation, high load stress, and high sand detachable ratio.

Addressing Actuator Saturation during Fault Compensation in Model-Based Underwater Vehicle Control

Robust control systems are a necessity for autonomous underwater vehicle (AUV) systems due to the challenges they face during operation. Many AUV control-design methods have been developed for different actuator configurations, with robustness against model parameter uncertainties, environmental disturbances, and system faults. Actuator faults can reduce the physical capabilities of a system, which can be compensated for through control re-allocation. However, the increased control allocation to the remaining actuators may cause actuator saturation and reduce controller performance. In this work, we present a depth-pitch model-based nonlinear control law that directly considers actuator saturation, and a fault-tolerant control allocation method for a hybrid AUV actuator configuration. Two types of actuator faults are considered for an underwater vehicle with a hybrid actuator configuration. The proposed controller is implemented in a simulated system, and its trajectory tracking performance is compared with a baseline system without fault or saturation tolerance. To determine the utility of the proposed saturation and fault tolerance control methods, the tracking performance in these simulations is quantified in terms of the settling time, post-fault peak values, and root mean square of the depth and pitch errors.

Comparative Analysis of Diffusion Metallization Coatings Applied on Steel Parts

In this paper the positive and negative aspects of diffusion metallization of steels were reviewed. It was shown that at high heating temperatures and prolonged exposure under these temperatures, steels show a tendency to enlarge austenitic grain. Overheating can occur at high exposure temperatures (T>1000ᵒC), which can be rectified by repeated heating however if burning of the steel microstructure occurs, it cannot be corrected. Given these circumstances, when assigning diffusion metallization modes, it is necessary to consider the factor of overheating or burning of steel in the process of exposure to high temperatures. To avoid this phenomenon, it is recommended to use alternative low-temperature processes of diffusion saturation of steels. Nitriding, nitro-cementation, gas-thermal spraying of the surface of steels are shown as such examples. It was suggested that these processes in comparison with diffusion metallization are more promising and acceptable for the restoration of worn surfaces of steels in the manufacture of parts of specialized equipment. Given that the parts of specialized equipment work in extreme conditions, repeated high-temperature heating of these steels is not recommended.To overcome the shortcomings of the diffusion metallization, the most frequently used coatings are applied by CVD, thermal spray, and cloth cladding techniques. As an alternative promising solution, the development of innovative methods of diffusion saturation, like an ion plantation of atoms on a relatively cold surface of the part could also be considered. It is shown that diffusion metallization is most acceptable for saturation of the surface of non-ferrous metals and alloys with the hardest and wear-resistant compounds.

Solubility of difluoromethane (R-32) and pentafluoroethane (R-125) in 1-alkyl-3-methylimidazolium tricyanomethanide ionic liquids

The recovery of refrigerant blends and the subsequent separation of value-added hydrofluorocarbons (HFCs) for reuse would help to meet the phase-down in the production of virgin HFCs established by the Kigali Amendment to the Montreal Protocol. The use of ionic liquids (ILs) in extractive distillation processes has become particularly relevant. In this process, the selection of the IL is the core element for a technically and economically feasible design. For this purpose, the absorption of the HFCs difluoromethane (R-32) and pentafluoroethane (R-125), components of the equimassic mixture R-410A, in 1-alkyl-3-methylimidazolium tricyanomethanide ILs was studied. The isochoric saturation method was applied to report vapor-liquid equilibrium data over a temperature range of 283.15–323.15 K and up to 0.9 MPa. These data were fitted accurately to the NRTL activity coefficient model and the Henry's law constants, the activity coefficients at infinite dilution, the enthalpies and entropies of solvation and the thermodynamic mixing properties were calculated. Finally, [C2C1im][tcm] ranked as one of the most selective ILs to date, exhibiting a good R-32 absorption capacity that could make it a valuable solvent for the separation of R-410A by extractive distillation.

Generation of Lime Recommendation Maps Using Traditional Thematic Maps and Management Zones

ABSTRACT The uniform management used in conventional agriculture is not the most efficient strategy for managing agricultural areas. In this way, precision agriculture (PA), based on assessments of the variability of chemical, physical, and biological attributes, seeks to optimize the activities management by site-specific management of inputs, to increase profitability in the production system, and to minimize environmental impacts. In this context, this work aimed to compare two techniques to make traditional thematic maps (TTMs) and management zones (MZs) for site-specific lime application, using data from three commercial agricultural areas (Western Paraná State, Brazil) and three methods to calculate the lime requirement (LR): (1) neutralization of exchangeable aluminum (Al3+) (NEM), (2) increase of calcium (Ca2+) and magnesium (Mg2+) (KM), and (3) base saturation method (BSM). The LR was calculated on AgDataBox-Map (ADB-Map) web platform, using AgDataBox-Map-Aplic module (ADB-Map-Aplic). ADB-Map is an application of the web platform, which aims at integrating data, software, procedures, and methodologies for Digital Agriculture. The Variance Reduction (VR%), Fuzziness Performance Index (FPI), Modified Partition Entropy (MPE), Improved Cluster Validation Index (ICVI), Smoothness Index (SI%) and Fragmentation index (FI%) indices were used to assess MZs quality, and the Kappa and global accuracy indices compared the agreement between TTMs and MZs. The results showed that the BSM method presented the best results in LR and distribution. According to the indices, MZs delineated with two classes generally (45 of the 47) showed the best results. MZs with application rates in each class calculated by the median of the lime quantities provided the lowest total LR per area. Thus, the MZs delineation allows applying lime more efficiently, reducing production costs, and allowing more sustainable use of inputs.

The Influence of Internal Control And Implementation of Principles Good Corporate Governance on Managerial Performance Case Study at Bank Rakyat Indonesia (BRI) Bogor City

This study aims to determine the effect of internal control and the application of the principles of good corporate governance on managerial performance at Bank Rakyat Indonesia (BRI) Bogor City. This research was conducted at Bank Rakyat Indonesia (BRI) Bogor City with a research time of one month and using a Likert scale. The population of this study were employees of the People's Bank of Indonesia (BRI) Bogor City by obtaining as many as 99 respondents and the samples were taken using the saturation or census method so that the total sample was 99 respondents. Sources of research data are primary data obtained through observation and distributing questionnaires via Google form to employees. The data analysis technique in this study is the analysis using the SEM Model with SMARTPLS 4.0.9.3. The results of the study show that internal control has a significant effect on managerial performance, and the application of good corporate governance principles has a significant effect on managerial performance at Bank Rakyat Indonesia (BRI) Bogor City.

An influence of molecular weight, deacetylation degree of chitosan xerogels on their antimicrobial activity and cytotoxicity. Comparison of chitosan materials obtained using lactic acid and CO2 saturation

This paper presents a comparison of the antimicrobial activity and cytotoxicity against L929 cells of chitosan xerogels prepared by dissolving the polymer in a solution of lactic acid (LA) or carbonic acid (CO2) and then freeze-drying. There was no simple relationship between the antimicrobial activity and cytotoxicity of the samples obtained using both techniques (LA and CO2). Chitosan materials obtained by the LA method in a 1:1 dilution were characterized by the highest cytotoxicity against L929 cells (∼20%). For the same diluted samples prepared using the CO2 saturation method, the viability of L929 cells was approximately 2.5 times greater. Some of the tested chitosan materials obtained by the innovative method were characterized by significantly lower antimicrobial activity, for example, reduction of E. coli bacteria for MMW-LA and MMW-CO2 samples by 6.00 and 0.75 logarithmic order, respectively. This clearly indicates that in many applications, the presence of the acid necessary to dissolve chitosan is responsible for the antimicrobial activity of the polymer solution and its products.