Bath Conditions Research Articles

Evaluation of Copper Sulfate Electroplating Solution and Film Quality Prediction Using Turbidity Measurement Method

Measuring and controlling the condition of the plating bath on the production line is important to achieve high quality plating and automation of the manufacturing process. Proper evaluation of plating solution degradation is one of the most pressing challenges in the copper sulfate electroplating process. However, constant monitoring and evaluation on the production line is difficult, and periodic sampling is used for evaluation. Optical measurement would be a simple and accurate method with which to achieve on-time and in-situ evaluation.We have developed a method to optically measure monovalent copper (Cu(I)) in a copper sulfate electroplating solution to evaluate the deterioration of the solution. Bathocuproinedisulfonic acid, disodium salt (BCS) specifically reacts with Cu(I) and forms an absorption band in the visible light region. By measuring its absorbance, it becomes possible to quantify the Cu(I) concentration in the aqueous solution. Absorbance measurement using BCS is a technology that can easily quantify Cu(I), making immediate measurement possible at production sites.Color reaction measurements are simple and suitable for production line applications, but like other methods, sampling is required. Furthermore, we proposed a method to evaluate plating solutions using fluorescence. This measurement detects the generation of fluorescence due to the decomposition of additives originally contained in the plating solution. There is no need to add special chemicals, and the state of the solution can be measured on the spot without sampling. However, this fluorescence is only effective when using Janus Green B (JGB) as an additive.On the other hand, light scattering can detect the formation of microparticles in solution. It is known that the accumulation of copper fine particles due to disproportionation reactions affects the quality of copper sulfate electroplated films. This suggests that the production of copper fine particles in the plating solution increases the light scattering intensity and can serve as an indicator of the degree of turbidity of the solution.In this study, we used a fluorometer to measure the intensity of light scattered in the direction perpendicular to the incident light as an indicator of the turbidity of the plating solution, and verified the relationship between the formation of fine particles due to energization and the increase in turbidity. This is equivalent to measuring turbidity using nephelometry. Furthermore, we will clarify the relationship between turbidity and Cu(I) accumulation and its effect on plating film quality, and consider its application to plating solution evaluation. Figure 1

Role of Glycine in the Electroless Fe-Ni-B Alloy Process for Power Semiconductor Devices

Pyrometallurgically produced Invar Fe-Ni alloys possessing an Fe content of 55–70 mass% exhibit a low coefficient of thermal expansion (CTE). Therefore, one can expect electroless deposited Invar Fe-Ni alloy films to also exhibit a low CTE comparable to those of semiconductor chips and insulating substrates used in semiconductor devices. However, a process for producing an Invar Fe-Ni alloy film by electroless plating has not been established and the thermal expansion properties of the obtained film have not been sufficiently investigated.We prepared electroless Fe-Ni-B alloy thin films using a citrate-pyrophosphate bath as a complexing agent and dimethylamine borane (DMAB) as a reducing agent, whereupon the thermal stress behavior of the thin films was evaluated [1]. In a previously reported plating process [1], the deposition rate of the Invar alloy plated film was 0.6 µm·h−1, which is too slow for practical applications. This deterioration in reaction rate of the electroless plating is caused by the high concentration of Fe2+, known as a stabilizer [2], in the plating bath. It is therefore necessary to improve the process to obtain the ~5–10 μm thickness required for high-density semiconductor packaging.In general, an increase in bath temperature and pH value improves the deposition rate, but this process limits the optimization of these operation conditions owing to the promotion of Fe2+ oxidation and the absence of stable complexes. Therefore, control of the deposition rate was attempted in this study by selecting a complexing agent in the plating bath. Here, we chose glycine [2], which is known to form a complex with Ni2+ in an electroless Ni plating bath and improve the deposition rate of electroless Ni. The glycine was added to the electroless Fe-Ni-B alloy plating bath, and the effect on the deposition of the Fe-Ni-B alloy film was investigated.Table 1 shows the electroless plating bath and plating conditions. The total metal-ion concentration was 50 mmol·L−1. A pure copper plate was used for the substrate, and a contact plating method was used where an aluminum plate was brought into contact with the substrate to initiate the deposition reaction. A 1 h plating time was used in each case.Fig. 1 shows Fe content and deposition rate of the electroless Fe-Ni-B alloy film obtained from the plating bath without or with addition of 1 to 100 mmol·L− 1 glycine, where ratios of Fe2+ / (Fe2+ + Ni2+) were 0.3 and 0.8. In both ratios of Fe2+ / (Fe2+ + Ni2+), Fe content was significantly reduced by adding of glycine of 10 mmol·L-1 or more. The deposition rate increased when glycine was added to the plating bath compared to that in the bath without glycine. When 100 mmol·L-1 of glycine was added, the deposition rate decreased compared to that when 10 mmol·L-1 was added.Using the stability constants of the complexes formed in the bath, it is estimated that when the glycine concentration is up to 10 mmol·L-1, it predominantly coordinates with Ni2+, whereas upon the addition of 100 mmol·L-1, it also forms complexes with Fe2+. As previously mentioned, the electroless plating process utilizing Ni2+ complex ions with glycine as a ligand exhibits a faster rate compared to deposition reactions involving other stable complex ions [2]. It is assumed that the Ni-glycine complex ion species with a high reduction rate becomes dominant in the plating bath containing 10 mmol·L-1 of glycine, so that the reduction rate of the Fe and Ni alloy is accelerated accompanied by acceleration of Ni2+ reduction and reached the maximum value.It turns out that by using glycine as a second complexing agent and optimizing its addition amount in an electroless Fe-Ni-B alloy plating bath, complex ions with a high reduction rate are formed, resulting in the improving of the deposition rate. Acknowledgement This work was supported by JSPS KAKENHI Grant Number JP24K08121.

Research on Measurement Algorithm of Thermocouple Time Constant Under Multiple Incentive Experimental Conditions

ABSTRACTThe time constant is often an important indicator parameter to evaluate the response speed of thermocouples. However, in practical applications, the output signal suffers from interference and deformation due to the excitation signal not satisfying the desired step size, data transmission delay, and the effect of mechanical vibrations, which do not match the output response of the system of the same order. In addition, the measurement results are not reproducible due to the subjective influence of the manual measurement method. In this paper, we propose a method to compute the time constant. The output signal is modified by filtering and fitting to enable the automatic calculation of the time constant, and the parameters of the algorithm are discussed. We developed a thermocouple time constant measurement device using a water bath and laser excitation conditions, obtaining response signals from thermocouples with different wire diameters and laser powers. The results demonstrate the effectiveness of the proposed time constant calculation methods in accurately capturing the changing trend of thermocouples with different wire diameters and laser powers. These methods successfully meet the requirements for processing the dynamic response signals of thermocouples under various excitation conditions.

Passive sampling of polycyclic aromatic hydrocarbons with low-density polyethylene: Equilibration limitations in aqueous suspensions

Polyethylene (PE) and other polymers are widely and successfully used as passive samplers for organic pollutants in the environment. This study provides high-resolution experimental data from batch shaking tests on the uptake, reversibility, and linear equilibrium partitioning of polycyclic aromatic hydrocarbons (PAHs) using two different PE sheets of 30 µm and 80 µm thickness. Kinetics for phenanthrene are well described by a mechanistic first-order model with mass transfer limited by an aqueous boundary layer (with a mean thickness of 170 µm). Equilibration in laboratory batch systems during uptake and desorption is very rapid with characteristic times of 1–2 h but this depends on the boundary condition, e.g., the ratio of PE mass to water volume. Therefore, equilibration of PE in other setups, e.g., in soil slurries or sediment suspensions, may take orders of magnitude longer because the boundary condition for PE changes from finite to infinite bath conditions (soil or sediment particles may keep the concentration in water almost constant). Solid precipitates for high molecular weight PAHs explain partition coefficients below expected values because of kinetic limitations in such a system. Nevertheless, passive sampling can be employed safely if such limitations are considered; furthermore, partition coefficients can be estimated accurately by empirical relationships (e.g., within 0.1 log unit) based on molecular weight, octanol/water partition coefficients, or subcooled liquid solubilities.

A major functional role of synovial fluid is to reduce the rate of cartilage fatigue failure under cyclical compressive loading

ObjectiveBased on our recent study, which showed that cartilage fatigue failure in reciprocating sliding contact results from cyclical compressive forces, not from cyclical frictional forces, we hypothesize that a major functional role for synovial fluid (SF) is to reduce the rate of articular cartilage fatigue failure from cyclical compressive loading. DesignThe rate of cartilage fatigue failure due to repetitive compressive loading was measured by sliding a glass lens against an immature bovine cartilage tibial plateau strip immersed in mature bovine SF, phosphate-buffered saline (PBS), or SF/PBS dilutions (50% SF and 25% SF; n=8 for all four bath conditions). After 24 hours of reciprocating sliding (5,400 cycles), samples were visually assessed and if damage was observed, the test was terminated; otherwise, testing was continued for 72 hours (16,200 cycles), with solution refreshed daily. ResultsAll eight samples in the PBS group exhibited physical damage after 24 hours, with an average final surface roughness of Rq=0.210±0.067 mm. The SF group showed no damage after 24 hours; however, two of eight samples became damaged after 72 hours, producing a significantly lower average surface roughness than the PBS group (Rq=0.059±0.030 mm; p<10−4). For the remaining groups, at 72 hours one of eight samples damaged in the 50% SF group, and five of eight samples damaged in the 25% SF group. ConclusionsThe results strongly support our hypothesis, showing that decreased amounts of SF in the testing bath produces increased rates of fatigue failure in cartilage that was subjected to reciprocating sliding contact.

Adsorption kinetics and thermodynamics of metal complex acid dyes on silk fabric

This study reports the adsorption phenomena of metal complex acid dyes onto silk fabric. Two commercial metal complex acid dyes namely Bestalan Yellow SF and Bestalan Navy SF were adsorbed onto degummed silk fabric. The functional properties and surface morphology of silk fabric were investigated with FT-IR spectroscopy and FE-SEM respectively. The typical absorption band of C = O stretching was found at 1620 cm−1 indicating amide I structure and C-N stretching as well as N-H bending vibrations were observed at 1510 cm−1 suggesting the β-sheet crystallites of amide I and amide II silk proteins. The effectiveness of degumming performance was confirmed by SEM images. The adsorption of dyes by silk fabric was investigated with respect to pH, initial dye bath concentration, and contact time. It was found that the adsorption of dye onto silk fabric was highly influenced by the dye bath pH, initial dye concentration, and contact time. The higher dye adsorption was observed at acidic dye bath condition (pH = 3.5). The adsorption of dye was also increased with the increase of the initial dye bath concentration. The dyes adsorption reached at equilibrium condition after 80 min. The adsorption isotherm and kinetics were also evaluated based on the experimental results. The adsorption pattern fitted well to the Langmuir adsorption isotherm with high correlation coefficient (R 2>0.97) for both dyes. The kinetic parameters suggested that the pseudo-second-order model is more suitable compare to the pseudo-first-order model considering the higher regression coefficients ( R 2 = ∼ 0.99 ) . The maximum adsorption of Bestalan Yellow SF and Bestalan Navy SF was found to be 232.5 and 222.2 mg/g respectively. The thermodynamic data were studied at 25, 40 and 60 °C. The change of Gibbs free energy of the system was positive indicating the spontaneous nature of the adsorption. The values of ΔH (-4.68 kJ/mole −3.65 kJ/mole) suggested the exothermic environment and the negative values of ΔS (-0.035 and −0.034 kJ/mole/k) advocated the good interaction between the metal complex acid dyes and silk fabric. The Langmuir adsorption model and pseudo-second-order kinetic suggested that the dyeing of metal complex acid dyes on silk fabric was controlled by ion-exchange chemical reaction.

Boyd’s film diffusion model for water contaminant adsorption: Time for an upgrade?

The Boyd film diffusion model is widely used in liquid phase adsorption studies for its mathematical simplicity and straightforward data analysis. However, a lack of awareness regarding its restrictive assumptions has led to widespread misuse. The Boyd model assumes film diffusion as the rate-controlling mechanism and rests on two additional pivotal assumptions: adsorption occurs under infinite bath conditions and follows a linear equilibrium relationship. This study examines the recurrent breaches of these assumptions across a growing body of research on water contaminant adsorption. Nearly all kinetic data have been derived from finite bath experiments governed by nonlinear isotherms, which directly contradict the Boyd model’s assumptions. Consequently, applying the Boyd model to such data can yield misleading results and interpretations. To address these challenges, alternative models tailored for finite bath conditions and capable of accommodating both linear and nonlinear isotherms should be considered. These models offer more accurate insights into adsorption kinetics under realistic experimental settings. While the Boyd model remains valuable under specific conditions, its stringent assumptions restrict its broader applicability. Researchers should critically assess the validity of these assumptions and explore alternative models when analyzing liquid phase adsorption kinetics to ensure robust and reliable results.

Designing Symmetric Gradient Honeycomb Structures with Carbon-Coated Iron-Based Composites for High-Efficiency Microwave Absorption

HighlightsMIL-88C (Fe) with varying aspect ratios as a precursor was synthesized by regulating oil bath conditions, followed by one-step thermal decomposition to obtain carbon-coated iron-based composites.High-efficiency microwave absorption properties were achieved with RLmin value of -67.4 dB (2.13 mm) and wide effective absorption bandwidth (EAB) of 5.52 GHz (1.90 mm) under the low filler loading.A symmetric gradient honeycomb structure was constructed utilizing the high-frequency structure simulator, achieving an EAB of 14.6 GHz and a RLmin of -59.0 dB.

Filament formation mechanisms in yield-stress fluid-enabled embedded ink writing

Embedded ink writing (EIW), an emerging material extrusion-based three-dimensional (3D) printing strategy, has demonstrated great potential for diverse applications. EIW consists of three key components: support bath, ink, and printing conditions. Filament formation in EIW is significantly affected by the coupling effects of these components, which is still unclear. This work aims to fundamentally unveil the filament formation processes and mechanisms within support bath materials with various rheological properties. A broader range of path speed is utilized to ensure the formation of diverse representative filaments from low- and high-viscosity hydrogel inks. By varying the combination of support bath, ink, and printing conditions, ten types of filaments are observed during EIW and their formation mechanisms are explained in detail. Particularly, when designing a support bath for EIW, thixotropic time serves as the baseline to determine the functionality of the bath. A relatively long thixotropic time can facilitate the formation of well-defined filaments. In addition, the support bath’s yield stress decides the allowed maximum path speed. High yield stress is necessary if path speed is targeted in a higher range. Based on the experimental findings, a position-shape-size evaluation system is established and proposed for comprehensively evaluating printed filaments, which is helpful in filtering suitable filaments for EIW. Finally, complex 3D structures including a human nose and a human ear are printed at a high speed within the support bath with suitable rheological properties to bridge the gap between filament formation mechanisms and practical 3D printing applications.

ZIF‐67 Derived Co‐LDH Nanocubes for Oxygen Evolution Reaction

AbstractTo address the substantial energy needs of the quickly evolving modern civilization, efforts are still needed to provide sustainable renewable energy sources. The electrocatalytic Oxygen evolution reaction (OER) is one of the essential technologies used in the various hydrogen production techniques. ZIF‐67 nanocubes (ZIF‐67 NCs) were synthesized in an aqueous solution and used as sacrificial templates. Cobalt nitrate hexahydrate was added under water bath conditions, resulting in the evolution of numerous small layered layers of cobalt hydroxide. This ultimately led to the formation of multilayered, three‐dimensionally crosslinked Co‐LDH with a porous networked cubic morphology. Hydrolysis of Co2+ at different concentrations produces different degrees of weak acidic environments, and the loose LDH on the cubic structure of the best catalyst, Co‐LDH‐1, exposes more active cobalt sites for the OER, which results in a high electrochemically active surface area, with an overpotential of 354 mV and a Tafel slope of 79.06 mV dec−1 at a current density of 10 mA cm−2, and good stability and low activation under alkaline condition also has good stability and low activation energy. It provides us an easy and practical plan for logically creating ZIF‐derived hydroxide materials, leading to the development of affordable and effective electrocatalysts.

Evaluation of Copper Sulfate Electroplating Solution and Film Using a New Method of Fluorescence Measurement

Control of plating bath conditions is an important issue on production lines. In this research, we developed a method for measuring and evaluating plating solutions using Janus Green B (JGB), a common additive, as a probe. It was discovered that when electricity was applied to a copper sulfate electroplating solution containing JGB as an additive, red fluorescence was generated. This is because the azo group of JGB is reductively cleaved by monovalent copper (Cu(I)) to produce a phenazine dye with red fluorescence. The fluorescence intensity depended on the energization current and time and was proportional to the concentration of JGB added. The fluorescence intensity indicates the rate of decrease in the concentration of JGB and can predict the deterioration of the quality of the plated film produced with the solution in a very early stage, and especially the occurrence of unevenness. Fluorescence is a simple and sensitive method of measurement that facilitates on-time and in situ measurement and evaluation of plating baths at the production site and is a useful method of bath management.

Preparation of BiOCl/Bi2S3 composites by polyol method for photocatalytic reduction of CO2

Abstract BiOCl/Bi2S3 composites were synthesized by polyol method under 80°C water bath condition, and the composite BiOCl/Bi2S3 has excellent photocatalytic activity for carbon dioxide compared with single BiOCl. Among them, BiOCl/Bi2S3-4 h has a higher conversion efficiency, which is mainly caused by the structural characteristics of BiOCl/Bi2S3 and the proportional content of Bi2S3 in the composite therein. The corresponding composites can be best formed in a hollow spherical morphology when the synthesis time is 4 h.

Longitudinal study of the Drowning Prevention Knowledge Level of schoolchildren in Rio de Janeiro, Brazil

Drowning is quick, silent and recognized as a serious public health problem worldwide, but it is neglected. Children and adolescents receive insufficient education about drowning prevention. The objective of this study was to monitor changes in the Drowning Prevention Knowledge Level (DPKL) in elementary school children and adolescents at CAp-UERJ, Rio de Janeiro, Brazil. The methodology was a longitudinal study carried out from 2022 to 2024 with students from the (5th, 6th, 7th, 8th and 9th years) of CAp-UERJ. 12 classes were monitored until 2024, totaling 336 students, four of which were in the 7th year, four in the 8th year and four in the 9th year, with a total of 112 students per year of schooling. A structured questionnaire divided into three parts containing 20 items about DPKL was answered at the school. In the 1st part, students correlated the universal figures used on signs to prevent drowning with the texts that signify those images (7 questions), in the 2nd part they had to relate the colors of the green, yellow and red flags and their meaning in regarding bathing conditions (3 questions) and in the last part, the student marked yes or no on statements related to the correct behavior to be adopted in the aquatic environment (10 questions). Each class received 3 interventions based on the individual DPKL result. When all years of schooling were analyzed together in three moments (2022, 2023 and 2024), the result showed that there was an improvement in knowledge about the 7 prevention signs, to the point that 99.1% of students now knew the meanings of the signs, and in two of them, sign no. 2, which refers to the emergency telephone and in no. 3, pushing prohibited, there was 100% accuracy. It was also possible to verify that after the intervention, almost all (98%) of the students correctly understood the meaning of the colors of the green, yellow and red flags. Regarding the behavior of playing nearby or putting their hand in the drain that sucks water from the pool, the result showed that the youngest were the ones who improved the most after intervention, going from 77.2% to 99.1% of those who responded correctly in 2024; about entering the pool, diving with a “somersault”, in a dangerous and inappropriate way, it was found that the older they were, the more aware of the danger caused by headfirst dives. Regarding the DPKL categorization, it was noted that 99% of students were classified as DPKL excellent in 2024. Those in the 8th and 9th years obtained 100% in the classification as DPKL excellent. It can be concluded that the school was a good place to carry out preventive interventions on drowning using an approach focused on behavior change, conceptual identification and student awareness in order to improve DPKL. The diagnostic use of DPKL to monitor school-age students can help identify safety values and concepts in certain regions of the country or specific groups that are not familiar with aquatic environments and thus help to formulate preventive interventions if necessary.

Precise Analysis of the Differences in the Laser-Activated Energy Density of Aluminum Nitride Ceramics under Various Gas Bath Environments

Laser activation can lead to the formation of a layer of aluminum on the surface of aluminum nitride ceramics, thereby preparing metal circuits. Under various gas environments, there are differences in the aluminum layers precipitated by laser-activated aluminum nitride ceramics. The existing literature uses the width of the metal layer to characterize this difference, and these data are very imprecise. Usually, laser energy density is used to describe this processing difference. However, the existing concept of laser energy density is an average value and is not suitable for the threshold of laser activation, because the intensity gradient of the focused Gaussian beam is large, and different intensity distributions represent different energy levels. This article applied a precise concept of laser energy density that sees it as being proportional to light intensity and can be used to evaluate the difference in laser energy density required for the decomposition of aluminum nitride ceramics under various gas bath conditions precisely. Due to the strong energy of a focused Gaussian beam, it is not possible to directly obtain the intensity distribution. Here, the intensity distribution of the collimated beam was used to indirectly obtain the intensity distribution of the focused Gaussian beam, and the threshold values for laser activation under different gas baths were calculated. It was found that the minimum energy density in air increased by 12.5%, and the minimum energy density in nitrogen increased by 3%, using the minimum energy density required for laser activation in argon as the reference.

Melting and separation behaviors of electric arc furnace dust pellets under iron bath conditions

To enhance the utilization capacity of zinc-containing electric arc furnace dust (EAFD), the reduction melting behavior of EAFD under iron bath conditions was empirically investigated. The sphericity of Fe droplets was defined as the judgment criterion for its coalescence, and then, the relationship between iron droplet diameter and sphericity was determined over time. The behavior of melting and separation of EAFD pellets was also established based on the experiments. The results showed that the Zn removal rate of EAFD pellets under iron bath conditions reached more than 99% at 5.0 min, but the metal−slag separation was not finished at 15.0 min. Due to the compositional fluctuation, several regions of liquid slag were formed in the EAFD pellets, and then, the liquid slag grew until the pellets melted completely. The number of Fe droplets with sphericity >65% and diameter >500 µm decreased with time, and large-diameter Fe droplets were the first to undergo complete separation. The separation process of slag and iron involved the initial formation of Fe droplets via Brownian motion, followed by an increase in the diameter of the iron droplets via the Marangoni effect. The Fe droplets in the slag phase drop rate resembled Stokes Law.

Simple and additive-free synthesis of highly reflective thin silver films and their application on large-scale surfaces

There is a growing demand for highly reflective coatings especially on non-conducting surfaces for use in various industries. Additionally, focus is arising on green production and cost reduction in terms of energy, time, etc., which require detailed investigation of coating process parameters. Therefore, in this work, silver thin films with high reflectance were synthesized on glass substrates in short durations at room temperature by electroless plating (ELP) method in one-step and without using any additives. Effects of deposition time, concentration of the reactants (AgNO3, Glucose, NaOH), and also the surface pretreatment and activation steps were investigated in detail to improve the reflectance and structural properties of silver films. Contact angle measurements were realized to examine the effects of each surface modification step. Surfaces subjected to etching, sensitization and Ag activation were found to yield more homogeneously distributed nanoparticles in short deposition period. Scanning electron microscopy (SEM) also showed smaller-sized spherulite-shaped crystals, forming a close packed structure with an optimum film thickness of ∼110 nm. The continuity of the silver coatings on the surface was verified by the low sheet resistance of 0.18 Ωsq−1. Atomic force microscopy (AFM) analysis revealed a smoother film structure with an RMS of 10.7 nm after sensitization. X-ray diffraction analysis (XRD) and X-ray photoelectron spectroscopy analysis (XPS) analysis proved the growth of highly crystalline silver nanoparticles with high purity. All these morphological improvements led to high values of light (∼97%), near-infrared (99%) and solar (96%) reflectance for the coatings. Finally, based on the optimized concentrations and bath conditions, large-scale (700×500 mm2) first-surface mirrors were successfully produced (96.2%R and 0.25 Ωsq−1) by spray coating technique combined with ELP. Overall, the results indicate that the obtained films have potential usage in applications such as solar energy, electronics and aeronautics.

Balneability of the Municipality of São Luis – MA and the Influence of Rainfall Occurrences as an Externality Factor

Objective: To analyze the bathing conditions, that is, the quality of the water intended for primary contact recreation on the beaches of Ponta D’areia, São Marcos, Calhau and Olho d’água located in the municipality of São Luís- Maranhão. Theoretical framework: This study was conducted based on theoretical reflections on environmental issues, the relationship between society and nature. Issues of water use for recreation, environmental policies regarding bathing and externalities that interfere with the quality of water for bathing and their impacts on the health of the population were analyzed. Method: To select beaches and water collection sites, the most intense flow of bathers and the risks of interference with water quality were taken into account. Data on bathing ability and average monthly precipitation were obtained to verify bathing conditions, in addition to information on effluent release points and urban drainage. Results and conclusion: It was observed that the main influence on the incidence of thermotolerant coliforms is the presence of sanitary effluents on beaches, this factor becomes visible in the rainy season and with the lack of sanitary infrastructure. Implications of the research: This research will contribute to public policy measures, helping decision-making to improve public and environmental health in the city of São Luís- MA. Originality/value: This study has socio-environmental and scientific value, as it relates bathing ability to externalities such as the lack of environmental sanitation and high rainfall in the region.

Studi Perbandingan Sifat Mekanik Mortar PPC dan Mortar Geopolimer dengan Aktivator NaOH pada Rendaman Air Laut

Using Portland pozzolan cement (PPC) is considered suitable for infrastructure in the sea area because it has a high resistance to salt and sulfate but still produces carbon dioxide gas emissions that can damage the environment. Environmentally friendly materials that can completely replace cement are geopolymer materials. This study compared the mechanical properties of PPC mortar and geopolymer mortar with and without white soil under seawater bath conditions. The test object is a 5x5x5 cm mortar cube with fly ash, white soil, sand, water, alkaline activator NaOH 8M, and PPC cement. Mortar variations include PPC mortar, geopolymer mortar without white soil substitution (TTP), and 15% white soil substitution mortar (TP15%). Tests include compressive strength, tensile strength, porosity, density, and absorption for all three variations. Microstructure testing of the influence of the bath is carried out on the TP15% mortar. The test results showed that PPC mortar has better resistance compared to both variations of geopolymer mortar in terms of its compressive and tensile strength at a bath life of 28 days, namely 32,427 MPa and 2,318 MPa, while the geopolymer mortar produced maximum compressive and tensile strength values of 14,373 MPa and 0.993 MPa. TTP mortar has better resistance than TP15% mortar. Microstructure testing showed mortar with baths had a denser matrix.

Microwave-enhanced selective leaching calcium from steelmaking slag to fix CO2 and produce high value-added CaCO3

The abundant resources of steel slag make it an intriguing prospect for long-term CO2 storage by mineral carbonation. Herein, the dissolution of steel slag in an acetic acid (HAc) solution and the fixation of CO2 in the leachate of steel slag to synthesize high-value CaCO3 were investigated. Results show that the microwave water bath condition is beneficial for improving the leaching rate of Ca and Mg elements in steel slag, while the low-concentration HAc solution displays high selectivity for Ca + Mg. In a water bath reaction enhanced by microwave, the leaching rate and selectivity of Ca + Mg can be increased by elevating the reaction temperature, extending the leaching time, lowering the concentration of HAc solution, and increasing the stirring rate. The kinetic parameters of the calcium element, including the apparent activation energy, were determined to be 14.51 kJ·mol−1, suggesting control by surface chemical reactions. Finally, high-purity CaCO3 crystal whiskers can be synthesized under 400 W ultrasonic conditions with a reaction temperature of 70 ℃, reaction time of 15 min, and a solution pH at 9.1 by introducing 20 % CO2 into the leachate. This strategy facilitates the concurrent utilization of dilute CO2 flue gas and voluminous solid steel slag waste, thereby improving the economic and environmental performance of the steel industry.

AdaBoost model-based rural governance co-integration and sharing mechanism

Abstract In this paper, we first study the implementation process of the AdaBoost model, initialize the weight distribution of training samples so that each sample weight is equal, then generate weak classifiers and calculate the minimum weighted error rate corresponding to each weak classifier, and then linearly combine the basic classifiers into strong classifiers by using weighted summation. Then the basic classifier weighting parameter calculation formula is improved by combining the characteristics of the logistics distribution function. Finally, the algorithm is used to analyze the rural governance willingness of river country residents, as well as to analyze the rural governance needs of rural residents at three levels: living conditions, public health and service facilities, to identify the types of rural governance, and to explore the rural governance patterns of different types of farm households. At the level of living conditions, farmers who wish to improve cooking fuel in 54 households, heating conditions in 61 households, bathing conditions in 40 households and family toilets in 53 households account for 43%, 49%, 32% and 42%, respectively. A total of 80 farming households, accounting for 29.41% of the research farming households, were optimized and upgraded, including 66 households in the key development area and 14 households in the production and living security area, accounting for 82.5% and 17.5% of the optimized and upgraded type, respectively. The research method of this paper has important references and reference significance for the construction of rural governance.