Cleaning Stage Research Articles

Dissolution Behavior of M5 Cladding in Hydrofluoric–Nitric Mixed Acid

M5 cladding has emerged as a prominent fuel cladding material due to its excellent corrosion resistance. The dissolution behavior of M5 cladding is critical in both the initial cleaning stage and the reprocessing of spent fuel cladding. This study investigated the dissolution of M5 cladding in hydrofluoric–nitric (HF-HNO3) mixed acid at varying concentrations. When the HF concentration exceeds 0.5 mol/L, the addition of strong oxidizing HNO3 significantly reduces the dissolution rate. Moreover, HNO3 effectively inhibits the HF-induced corrosion pitting, lowering surface roughness to 0.812 μm at a 1:5 ratio of HF:HNO3. In addition, a surface structural analysis reveals the dissolution mechanism of M5 cladding. The β-Nb precipitated in the mixed acid was oxidized to stable Nb2O5 by HNO3 while the M5 matrix surface was continuously oxidized to ZrO2. This passivation layer inhibits further dissolution, slowing the process and enhancing the uniformity of M5 cladding.

Faktor Penyebab yang Paling Dominan Kejadian Dermatitis Kontak Iritan pada Pekerja di TPA (Tempat Pemrosesan Akhir) Talang Gulo Kota Jambi

This study aims to analyze the dominant causal factors of subjective complaints of irritant contact dermatitis in workers at the Talang Gulo Landfill in Jambi City. The data analysis method in this study explains the stages of analysis, namely starting with data collection, data processing and data analysis. Data collection was carried out by the researcher himself and assisted by three enumerators and the head of waste management at the Talang Gulo Landfill. The data that has been obtained is then collected, processed according to the objectives and conceptual framework of the study. After the data is collected, data processing is carried out. Data processing is carried out through the stages of editing, coding, data entry, and data cleaning. The data that has been processed is then analyzed using univariate analysis, bivariate analysis and multivariate analysis. The results of the study showed that the factors related to subjective complaints of irritant contact dermatitis are knowledge, chemical exposure from waste and personal hygiene. Of the three factors, personal hygiene is the most dominant factor in the occurrence of subjective complaints of irritant contact dermatitis. Respondents who have poor personal hygiene have a 6.123 times higher risk of experiencing subjective complaints of irritant contact dermatitis when compared to respondents who have good personal hygiene after being controlled with the variables of knowledge and chemical exposure from waste.

Long-Term Monitoring of Microplastics in a German Municipal Wastewater Treatment Plant

Wastewater treatment plants (WWTPs) have been identified as important point sources for microplastics (MPs) in the environment; monitoring MP emissions in the WWTP effluent is therefore essential for contamination control. The aim of this study is to acquire a large number of samples (320) over a period of two years and three months to determine the temporal variations in microplastic contamination in the outlet of the municipal WWTP Landau-Mörlheim. The effluent of the third cleaning stage is sampled with a 10 µm filter cartridge, processed in the laboratory using a hydrogen peroxide treatment, and MPs are then detected by fluorescence staining. The results show high temporal variations in the microplastic concentrations in the effluent of the WWTP. This indicates that high numbers of samples are necessary to obtain a representative assessment of the microplastic emissions; single samples are not representative. The average microplastic concentration in the effluent was 27.8 ± 29.8 MP/L, ranging from 0.6 MP/L to 194.0 MP/L. This leads to a yearly emission of 1.5 × 1011 MP for the WWTP Landau-Mörlheim, corresponding to an emission of 2.8 × 106 MP/inhabitant and year. Statistically significant seasonal variations could not be observed, although there is a trend towards lower MP concentrations in summer. Further, no correlations with other wastewater or weather parameters could be found.

ImhoflotTM Flotation Cell Performance in Mini-Pilot and Industrial Scales on the Acacia Copper Ore

The present work investigates a comparative study between mechanical and ImhoflotTM cells on a mini-pilot scale and the applicability of one self-aspirated H-16 cell (hybrid ImhoflotTM cell) on an industrial scale on-site. The VM-04 cell (vertical feed to the separator vessel with 400 mm diameter) was fabricated, developed, and examined. The copper flotation experiments were conducted under similar volumetric conditions for both the ImhoflotTM and mechanical flotation cells keeping the rest of the parameters constant. Further, one H-16 cell was positioned at four different stages in the Gökirmak copper flotation circuit of the Acacia (Türkiye) copper beneficiation plant, i.e., at (i) pre-rougher flotation, (ii) rougher concentrate, (iii) cleaner-scavenger tailing, and (iv) first cleaning concentrate aiming at enhancing the flotation circuit capacity through flash flotation in the rougher stage, reducing copper grade in the final tailing, and increasing cleaning throughput, respectively. Comparative copper flotation tests showed that ultimate recoveries using the ImhoflotTM and mechanically agitated conventional cells were 94% and 74%, respectively. The industrial scale test results indicated that locating one pneumatic H-16 cell with the duty of pre-floating (also known as flash flotation) led to the enrichment ratio and recovery of 4.84 and 89%, respectively. Positioning the H-16 cell at the cleaner-scavenger tailings could diminish the copper tailings grade from 0.43% to 0.31%. Further, a relatively greater enrichment ratio and copper recovery were obtained using only one ImhoflotTM cell (1.76 and 64%) in comparison with employing four existing mechanical cells (50 m3, each cell) in series (1.45 and 60%) at the first cleaner stage.

Improvement of the method of processing animal bones in the production of educational and museum exhibits

The method of processing the bones of domestic and wild animals has been improved and maximally adapted to domestic conditions. The work was carried out on the basis of the laboratory of taxidermy and museum affairs of the department of anatomy and histology named after Р. Kowalskiy Bilа Tserkva National Agrarian University. The aim of the work was the practical application of the improved method of processing the bones of domestic and wild animals for the production of museum exhibits and educational materials. For the treatment and degreasing of bones, Pervol and Gala washing powders with a whitening effect and Fairy brand dishwashing detergents used as surfactants. Precursor-free chemical paint solvents 646, 647, 650 and White Spirit have proven themselves well as solvents for intraosseous fat. At the stage of preparation and cleaning of the bones from the muscles, they were subjected to maceration in water at room temperature for 7-10 days. Degreasing of bones in solvents lasted up to 1.5 months with daily visual control and mixing. Visual control have carried out by illuminating the bones with lamps with bright light. 60% perhydrol diluted with water in a ratio of 1:4 was used as a bleaching agent. As a result of comparative testing of various means, it was established that it is better to use deep penetration soil "Artisan No. 7" with exposure of bones in it for up to 7 days as a fxing preparation. It should be noted that chemical treatment of bones using household detergents and technical solvents is quite effective and affordable, although it takes a long time. The proposed method makes it possible to produce high-quality, visually aesthetic and tactilely pleasant, absolutely odorless, uniformly white educational preparations and museum exhibits of bones with minimal fnancial costs and technical equipment. Key words: domestic, wild animals, skeleton bones odorless, solvent.

Measuring the impact of ginning stages on cotton fiber quality in the context of west and central Africa

The ginning process has an effect on fiber quality. Avoiding fiber quality deterioration due to mistune or overspeed is crucial, especially in west and central Africa where value chains are highly dependent on prices paid for premium fiber quality. Indeed, fiber classification alone does not permit a reliable measurement of ginning impact, as it depends on many factors such as incoming seed cotton quality, equipment type, number, and settings within each ginning process stage. This study describes a sampling and analysis method precise enough to detect any commercial impact on fiber quality at each main ginning stage. It is based on fiber quality characteristic measurements before and after each main stage: seed cotton cleaning, ginning, and lint cleaning. The sampling and testing protocol was applied in Mali in seven industrial gins during the 2015–2016 ginning season. Seed cotton samples were taken before and after the seed cotton cleaning stage, and fiber samples before and after the lint cleaning stage. Seed cotton samples were ginned with a reference saw micro-gin. The precision of fiber characterization was measured by replicating twice each fiber sample characterization in a laboratory meeting the international standards. Based on the variability measured in Mali, we determined for each fiber characteristic the number of replicates required to detect any commercially harmful impact. Growing and ginning conditions in Mali are representative of those in west and central Africa. Based on this method, one needs to develop an on-line tool to measure fiber quality at every stage of industrial ginning.

Determination of an axial gas cyclone separator cut-off point by CFD numerical modeling

Determination of an axial gas cyclone separator cut-off point by CFD numerical modeling

Direct flotation separation of active materials from the black mass of lithium nickel cobalt manganese oxides-type spent lithium-ion batteries

Batteries based on lithium nickel cobalt manganese oxides (NCM), which have not been extensively studied, were considered for this study. A black mass (BM) derived from a diverse mix of NCM-type batteries was pyrolyzed at three different temperatures before flotation. The optimum pyrolysis temperature was determined via X-ray spectrometry, contact angle measurements, thermogravimetry, X-ray diffraction, and X-ray photoelectron spectroscopy as 400 °C at which the active materials in the BM were successfully liberated without generating new phases on the material surfaces. This is crucial for recovering materials from the BM using flotation and their potential subsequent application in battery manufacturing, which requires high-purity materials. After optimal pretreatment, the flotation of the treated BM was conducted to separate active materials. At the laboratory scale, the optimal conditions were an impeller speed of 1600 rpm, a collector dosage of 150 g/t, a frother dosage of 150 g/t, and a pulp density of 20 g/L. Furthermore, the initial anode and cathode grades of 84 % and 92 % were further enhanced to 97 % and 95 %, respectively, by employing additional cleaning and scavenging stages. Therefore, this study offers a promising method for recovering high-purity active materials from the BM through systematic pyrolysis pretreatment and subsequent flotation.

The Effect of Pre-Anesthesia Assessment on Patient Safety in the Operating Room

Background: The development of the science of anesthesia provides consideration in administering the type of anesthesia used. The pre-anesthesia assessment is the basis for planning the findings on the monitor during and after anesthesia. The completeness of the pre-anesthesia assessment has an important role in patient safety, if the anesthetic assessment is not properly completed it allows errors in the operation process. Patient safety goals are the main requirement to be implemented in all hospitals accredited by KARS. Patient safety goals intend to drive specific improvements in patient safety. This goal highlights problematic areas of health care. The wrong-site, wrong procedure and wrong-patient surgery are something that is worrying and not uncommon in the hospital. This error resulted from ineffective communication between members of the surgical team, not involving the patient in site marking, and no procedure for verifying the surgical site. Objective: The study aims to see the effect of the completeness of the pre-anesthesia assessment on patient safety. Methods: The research design is a cross-sectional study. The population in this study were patients who underwent surgery with a total sample of 70 people. Data processing through the stages of editing, coding, entry, and cleaning. Univariate analysis and bivariate analysis used the chi-square test with a 95% degree of confidence α = 0.05. Results: The results showed that the completeness of the pre-anesthesia assessment was complete with a percentage of 88.6%. Good patient safety with a percentage of 65.7%. There was no significant relationship between the completeness of the pre-anesthesia assessment and patient safety (p=0.076). Conclusions: To improve the implementation of pre-anesthesia assessments, hospitals need to review the completeness of filling out pre-anesthesia assessments by anesthesiologists before patients are operated on, to prevent errors in improving patient safety. Prepare facilities and infrastructure for the needs of patient safety programs by accreditation standards.

Quality indicators for the processing of health products: A mixed-methods study.

to analyze the use of quality assessment indicators and their implementation to improve quality in the processing of health products. a mixed-methods study with a multiple case approach using Structure, Process and Results indicators and elaboration of a plan using Appreciative Inquiry, carried out in four central sterile supply departments from hospital units. the indicators for the Cleaning stage presented 47.8% compliance for Structure and 59.0% for Process: in addition 71.8% of the products were clean. In the Preparation operational stage, 50.0% of the Results indicators were in compliance for Structure and 66.7% for Process. In the Sterilization, Storage and Distribution stage, 43.5%compliance was obtained for Structure, 55.7% for Process and 78.6% for Packaging conservation. Appreciative planning proposed improvements to the physical structure, review of processes and protocols, promotion and appreciation of the work done and strengthening of teaching about processing and service management, highlighting the protagonism of the group and of the leaders. using indicators was positive in materializing reality; however, it was verified that the improvements proposed are related to people. The affirmative and constructive view of Appreciative Inquiry presented itself as a path to changes and quality improvements.

Effect of a disposable endoscope precleaning kit in the cleaning procedure of gastrointestinal endoscope: A multi-center observational study.

Precleaning is a key step in endoscopic reprocessing. To develop an effective and economic endoscope cleaning method by using a disposable endoscope bedside precleaning kit. Altogether, 228 used gastrointestinal endoscopes were selected from five high-volume endoscopy units and precleaned by a traditional precleaning bucket (group T) or a disposable endoscope bedside precleaning kit (group D). Each group was further subdivided based on the replacement frequency of the cleaning solution, which was replaced every time in subgroups T1 and D1 and every several times in subgroups Ts and Ds. The adenosine triphosphate (ATP) level and residual proteins were measured three times: Before and after precleaning and after manual cleaning. After precleaning, the precleaning kit significantly reduced the ATP levels (P = 0.034) and has a more stable ATP clearance rate than the traditional precleaning bucket. The precleaning kit also saved a quarter of the cost of enzymatic detergent used during the precleaning process. After manual cleaning, the ATP levels were also significantly lower in the precleaning kit group than in the traditional precleaning bucket group (P < 0.05). Meanwhile, the number of uses of the cleaning solution (up to four times) has no significant impact on the cleaning effect (P > 0.05). Considering its economic cost and cleaning effect, the use of a disposable endoscope bedside precleaning kit can be an optimal option in the precleaning stage with the cleaning solution being replaced several times in the manual cleaning stage.

ANALYSIS OF WASTE GAS CLEANING METHODS FROM SULFUR DIOXIDE

It is shown that sulfur dioxide is one of the most common components of harmful emissions into the atmosphere.&#x0D; It is presented that a large amount of SO2 is emitted into the atmosphere in the production of sulfuric acid, during the combustion of fuel in thermal power plants, in modern production of surfactants.&#x0D; Sulfur dioxide has been shown to be responsible for the formation of acid rain, which is one of the most common forms of pollution worldwide.&#x0D; The transport of sulfur compounds over long distances leads to the deposition of sulfur dioxide in soils and waterways.&#x0D; It is known that all known methods of waste gas purification are divided into three main groups: ammonia methods, SO2 neutralization methods, catalytic methods.&#x0D; In the general case, absorption methods are divided into open and circulating cleaning schemes.&#x0D; It is shown that ammonia-acid methods are economical, but require the cost of a scarce product – ammonia.&#x0D; The ammonia-sulfuric acid method consists in the treatment of ammonium bisulfite with sulfuric acid.&#x0D; When using the ammonia-phosphorus-acid method, phosphorus methods and sulfuric acid are formed.&#x0D; The soda method is based on the absorption of sulfur dioxide by a suspension of CaO.&#x0D; The lime method is based on the absorption of sulfur dioxide by a suspension of CaO.&#x0D; It is shown that when using a sodium hydroxide solution as an absorbent, both open-loop and circulating cleaning schemes are used.&#x0D; Open circuits are characterized by simple hardware design, as well as low energy for cleaning.&#x0D; It has been shown that catalytic methods for cleaning exhaust gases do not require the use of an absorbent. However, it is necessary to use an expensive catalyst. More often, this method is used at the first stage of cleaning, and at the second – the above methods of cleaning.&#x0D; A table with comparative technical and economic indicators is given.&#x0D; It is shown that for the production of surfactants it is better to use open-loop purification schemes.&#x0D; It is suggested that sodium hydroxide solution can be chosen as the absorbent. With the content of small amounts of sodium sulfite in a solution of sodium hydroxide, it can be used as a neutralizing agent in the neutralization of sulfation products.

ANALYSIS OF WASTE GASES CLEANING METHODS FROM SULFUR DIOXIDE

It is shown that sulfur dioxide is one of the most common components of harmful emissions into the atmosphere. It is stated that a large amount of SO2 is emitted into the atmosphere in the production of sulfuric acid, during fuel combustion in thermal power plants, and in modern production of surface-active substances.&#x0D; It has been shown that sulfur dioxide is responsible for the formation of acid rain, which is one of the most common forms of pollution around the world.&#x0D; It is stated that all known methods of waste gas purification are divided into three main groups: ammonia methods, SO2 neutralization methods, catalytic methods.&#x0D; In general, absorption methods are divided into open and circulation cleaning schemes.&#x0D; It is shown that ammonia-acid methods are economical, but require consumption of a scarce product - ammonia.&#x0D; The ammonia-sulfuric-acid method consists in treating ammonium bisulfite with sulfuric acid.&#x0D; When using the ammonia-phosphoric-acid cleaning method, phosphoric fertilizers and SO2 are formed, which can be further processed into sulfuric acid.&#x0D; The sodium method is based on the absorption of sulfur dioxide by a CaO suspension.&#x0D; It is indicated that when using a solution of sodium hydroxide as an absorbent, both open and circulating cleaning schemes are used.&#x0D; It is shown that catalytic methods of waste gas purification do not require the use of an absorbent. However, it is necessary to use an expensive catalyst. Most often, this method is used at the first stage of cleaning, and at the second - the cleaning methods listed above.&#x0D; The table with comparative technical and economic indicators is presented, the choice of one or another cleaning method depends on specific production conditions.&#x0D; It is shown that for the production of surface-active substances it is better to use open cleaning schemes, which are distinguished by the simplicity of the equipment design, as well as the low consumption of energy for cleaning.&#x0D; It is stated that sodium hydroxide solution can be chosen as an absorbent. If the sodium hydroxide solution contains small amounts of sodium sulfite, it can be used as a neutralizing agent in the neutralization of sulfation products.

Анализ технологий заканчивания скважин с установкой скользящих муфт на фильтр

Mechanical cleaning filters are used to purify water, aqueous solutions, liquid and gaseous substances, hy-drocarbons, air from solid suspended particles of various sizes. Filters used in the field are steel cylindrical apparatuses with a solid and detachable body, inside which slotted or mesh filter partitions are installed, contributing to the purification of water. The principle of operation of mechanical cleaning filters is that when the filtrated medium passes through the filter element, solid particles will be retained. The main feature of such filters is the frequency of action due to the need to clean the filter element manually or automatically using a reverse flow of clean water. With a decrease in productivity, namely, with an increase in the pressure drop between the inlet and outlet, as well as in the lower part of the device, manual or automatic cleaning of the filter element from accumulated contaminants will occur. The article highlights the principle of sliding couplings for filters for water purification, as well as their use in construction. The stages of cleaning and the materials from which sliding filters are made to prevent leakage are considered. Recommendations are given for careful monitoring and following proper procedures to prevent leaks and pressure losses, to ensure the structural integrity and stability of the well, as well as to exclude contamination of the surrounding groundwater. The use of a mechanical filter is proposed, the body of which is designed for heating or fixing thermal insulation and which can be used with small flows of viscous media for cleaning from impurities.

Experience in the use of endovenous methods and cell technologies in the treatment of patients with chronic venous insufficiency C6.

&lt;b&gt;&lt;br&gt;Introduction:&lt;/b&gt; Severe forms of chronic venous insufficiency (CVI) CEAP C3-C6 occur in 17-20% of all CVI cases among adults.&lt;/br&gt; &lt;b&gt;&lt;br&gt;Aim:&lt;/b&gt; The aim of this study was to compare the standard treatment of CVI C6 with endovenous methods and cellular technologies.&lt;/br&gt; &lt;b&gt;&lt;br&gt;Materials and methods:&lt;/b&gt; Group I consisted of 28 patients with trophic ulceration treated using modern wound coverings, cell technologies and minimally invasive operations. Group II had 42 patients with trophic ulceration who underwent crossectomy with stripping of the trunk of the target vein and local treatment with "standard" ointments. The results of the treatments were evaluated using the Venous Clinical Severity Score (VCSS), the Numeric Pain Rating Scale (NPRS), and ulcer healing time.&lt;/br&gt; &lt;b&gt;&lt;br&gt;Results:&lt;/b&gt; After 1 month, the VCSS scores were 13.8 2.3 and 16.4 3.3 points in Groups I and II, respectively; after 3 months, they were 10.2 2.1 and 13.6 2.4 points. VLU was healed in 20 (71.43%) and 16 patients (38%) after 3 months in Groups I and II, respectively; in 26 (92.86%) and 30 patients (71.43%) after 6 months; and in 28 (100%) and 40 patients (95.24%) after 12 months. After 1, 3, and 6 months, occlusion of the target segment was achieved in 14 patients (100%) of Group I. NPRS was significantly lower in Group I. The hospital stay in Group I was 8.2 2.4 days, while for Group II it was 14.5 3.8 days.&lt;/br&gt; &lt;b&gt;&lt;br&gt;Conclusions:&lt;/b&gt; The use of modern wound coverings, platelet-rich plasma (PRP), and negative-pressure wound therapy (NPWT) reduced the period of preoperative preparation and sped up the stage of cleaning and healing of VLU compared to conventional wound coverings in patients with CVI C6.&lt;/br&gt.

Quantifying narrowing partition thickness in a vertical pneumatic separation channel for soybean seed cleaning

The paper highlights that the study of the soybean seed separation processes in a vertical deep aspirating channel contributes to the improvement of technical and economic indicators in grain cleaning equipment. (Research purpose) The research aims to substantiate the thickness of narrowing partitions in the vertical deep aspirating channel. (Materials and methods) A prototype of a vertical deep aspirating channel with three sections of varying height, was used for cleaning soybean seeds. The optimal thickness of the narrowing partitions in the channel has been justified. Impurity extraction completeness and seed separation efficiency within a vertical aspirating channel were assessed for soybean seed cleaning under maximum specific grain load conditions. (Results and discussion) The following parameters have been determined: the optimal thickness for the narrowing partitions is 70 millimeters under a maximum specific grain load of 5 kilograms per square centimeter per hour. Seed losses do not exceed 3 percent in the aspirating channel with narrowing partitions, with impurity extraction completeness of 74 percent for the «Waste» fraction. The efficiency of the separation process stands at 71 percent, and the purity level of the «Seeds» fraction reaches 81 percent in a single pass during the preliminary cleaning stage. (Conclusions) It has been established that the use of narrowing partitions in a vertical aspirating channel during soybean seed cleaning leads to an increase in the specific grain load up to 5 kilograms per square centimeter per hour, compared to 2 kilograms per square centimeter per hour achieved by traditional pneumatic separation channels. The proposed technical solution reduces soybean seed losses to 3 percent (compared to the initial requirements of no more than 10 percent) in a single pass and reduces machine power consumption from 4.5 to 2.25 kilowatt-hours.

Adaptive Android APKs Reverse Engineering for Features Processing in Machine Learning Malware Detection

The key component that makes the detection of android malware possible is the availability of the right triggers and pointers, which are found in the Android application packages, known as features or attributes. These are fundamental in the training of the different machine learning algorithms to produce the required detection model. The process of extracting these attributes or features, from the Android application packages, is known as reverse engineering. This paper delved into the experimental detail processes of applying reverse engineering procedure, using Sublime Text 2 and Androguard Plugin, on Android Application packages for the extraction of, particularly permissions, which are the targeted features. The study further discussed the cleaning stages, using NotePad++, Microsoft Excel Worksheet, and MS Word, to sort out all the relevant and important features by removing all the noisy ones. A total of 1500 Android apps were downloaded from both benign and malicious sources and used for the experiment. The cleaned or important features extracted from these application packages at the end of the reverse engineering processes are 162 in total and these were further used to form a feature binary matrix of size 1500 by 163 (including the class features).

Changes in Secondary Inorganic Ions in PM2.5 at Different Pollution Stages Before and After COVID-19 Control

To investigate the change characteristics of secondary inorganic ions in PM2.5 at different pollution stages before and after COVID-19, the online monitoring of winter meteorological and atmospheric pollutant concentrations in Zhengzhou from December 15, 2019 to February 15, 2020 was conducted using a high-resolution (1 h) online instrument. This study analyzed the causes of the haze process of COVID-19, the diurnal variation characteristics of air pollutants, and the distribution characteristics of air pollutants at different stages of haze.The results showed that Zhengzhou was mainly controlled by the high-pressure ridge during the haze process, and the weather situation was stable, which was conducive to the accumulation of air pollutants. SNA was the main component of water-soluble ions, accounting for more than 90%. Home isolation measures during COVID-19 had different impacts on the distribution characteristics of air pollutants in different haze stages. After COVID-19, the concentration of PM2.5 in the clean, occurrence, and dissipation stages increased compared with that before COVID-19 but significantly decreased in the development stage. The home isolation policy significantly reduced the high value of PM2.5. The concentrations of NO2, SO2, NH3, and CO were the highest in the haze development stage, showing a trend of first increasing and then decreasing. The concentration of O3 was lowest in the pre-COVID-19 development stage but highest in the post-COVID-19 development stage. The linear correlation between[NH4+]/[SO42-] and[NO3-]/[SO42-] at different time periods before and after COVID-19 was strong, indicating that the home isolation policy of COVID-19 did not change the generation mode of NO3-, and the corresponding reaction was always the main generation mode of NO3-. The correlation between[excess-NH4+] and[NO3-] was high in different periods before COVID-19, and NO3- generation was related to the increase in NH3 or NH4+ in the process of PM2.5 pollution in Zhengzhou.

BIOLOGICAL WASTEWATER TREATMENT: BASIC CONCEPTS AND STAGES OF CLEANING

BIOLOGICAL WASTEWATER TREATMENT: BASIC CONCEPTS AND STAGES OF CLEANING

Main properties of silicides of the Mo - Si system

Using magnetron-ion sputtering, a layer of metallic molybdenum 1–2 μm thick was deposited on the surface of a silicon single crystal grown by the Czochralski method in an atmosphere of an inert argon gas at ambient temperature. According to the results of the experiment, pure Mo layers 2 μm thick deposited by magnetron reactive sputtering from a highly pure metal molybdenum target onto a cold silicon wafer substrate with a thickness of 1.5 mm. They have simultaneously high conductivity and transparency only in the case when a strictly defined deposition rate of molybdenum metal corresponds to a given partial pressure of argon in the volume. The sputtered targets are disks 40 mm in diameter with a thickness of 3-4 mm. The technological cycle of product processing includes the stage of target cleaning. Sputtering of a metal Mo target in pure argon Ar without the addition of oxygen promotes the formation of opaque metal films with very good conductivity. X-ray diffraction analysis of silicon monocrystals with a Mo metal-coated surface revealed compounds Mo3Si and MoSi0.65 in the molybdenum-silicon system. Silicon silicide MoSi2 was found to undergo an allotropic transformation in the temperature range 1850 ÷ 1900 °C, and the low- temperature variety α-MoSi2 has a tetragonal structure. The high- temperature form of β-MoSi2 has a hexagonal structure. The results of the study with an atomic scanning microscope showed that the chains of silicon atoms, connecting with Mo atoms, form zigzags passing through the prisms of the Mo structure along parallel X and Y axes.