Agitation Conditions Research Articles

Optimized Conditions for the Long-Term Maintenance of Precision-Cut Murine Myocardium in Biomimetic Tissue Culture

Organotypic heart slices from mice might provide a promising in vitro model for cardiac research because of the vast availability of genetically modified specimens, combined with the unrestricted feasibility of experimental interventions. However, murine heart slices undergo rapid degeneration in culture. Therefore, we developed optimal conditions to preserve their structure and function in culture. Mouse ventricular heart samples were transversely cut into 300 µm thick slices. Slices were then cultured under various conditions of diastolic preload, systolic compliance and medium agitation. Continuous stimulation was performed either by optical stimulation or by electrical field stimulation. Contractility was continuously measured, and cellular survival, structure and gene expression were analyzed. Significant improvements in viability and function were achieved by elastic fixation with the appropriate diastolic preload and the rapid shaking of a ß-mercaptoethanol-supplemented medium. At 1 Hz pacing, mouse heart slices maintained stable contractility for up to 48 h under optogenetic pacing and for one week under electrical pacing. In cultured slices, the native myofibril structure was well preserved, and the mRNAs of myosin light chain, titin and connexin 43 were constantly expressed. Conclusions: Adult murine heart slices can be preserved for one week and provide a new opportunity to study cardiac functions.

Azospirillum baldaniorum Sp 245 inoculation affects cell wall and polyamines metabolisms in cucumber seedling roots.

Azospirillum baldaniorum Sp 245 is a model plant growth-promoting rhizobacterium. The first cross-talk with plants takes place within the roots. Roots cells growth is constrained by the primary cell wall (CW). Also, neighboring CW form the apoplast that should affect cells signaling and biochemical messages. Studies on CW phenolic composition ferulate (FA), diferulates (DFA) and p-coumarate and polyamines (PA) metabolisms of A. baldaniorum Sp 245- inoculated roots and on bacterial PA production in culture media should help to understand more about the mechanisms involved in Azospirillum-root association. For this purpose, CW-bound FA, DFA and p-coumarate contents, putrescine (put) and spermidine contents, diamine and polyamine oxidases activities, and H2O2 content of Cucumis sativus roots from dark grown seedlings inoculated with A. baldaniorum Sp 245 were determined. Also, bacterial PA production under constant agitation or static conditions was evaluated. Results showed lesser contents of all phenolics, and higher FA/DFA ratio in CW of inoculated roots that should be responsible for roots growth promotion. Also, the increased put content, DAO activity, and H2O2 production in the roots should be associated to A. baldaniorum Sp 245 growth promotion in early stages. Finally, the participation of both PA in A. baldaniorum Sp 245 biofilm formation was demonstrated.

Production of palmitoleic acid by oleaginous yeast Scheffersomyces segobiensis DSM 27193 using systematic dissolved oxygen regulation strategy

Palmitoleic acid (POA) can be naturally found only in few oil seeds and has significant applications in pharmaceutical industry. Recently, the isolated oleaginous yeast Scheffersomyces segobiensis DSM 27193 was identified with high content of POA in its intracellular lipid (13.80%). In this study, process optimization focused on dissolved oxygen regulation to improve POA production was conducted. Dynamic agitation was found to do significant enhancement on POA-rich lipid production than aeration regulation. Under the best condition of 1000 r·min−1 of agitation and 1 vvm (airvolume/culture volume/min) of aeration, no ethanol was detected during the whole fermentation process, while a dry biomass concentration of 44.80 g·L−1 with 13.43 g·L−1 of lipid and 2.93 g·L−1 of POA was achieved. Transcription analysis revealed that the ethanol synthetic pathway was downregulated under the condition of high agitation, while the expression of the key enzymes responsible for lipid and POA accumulation were enhanced.

Production of mycelial biomass, proteases and protease inhibitors by Ganoderma lucidum under different submerged fermentation conditions.

Ganoderma lucidum is a medicinal mushroom widely recognized as a source of biomolecules with pharmacological properties, however, little is known about the factors that influence the synthesis of bioactive proteins by this fungus when cultivated under submerged fermentation. The objective of this work was to evaluate the production of mycelial biomass and intracellular proteases and protease inhibitors by G. lucidum cultivated under different submerged fermentation conditions. The cultivation was carried out in a medium composed of glucose (10 or 20 g.L-1), soy peptone (2.5 or 5 g.L-1) and yeast extract (5 g.L-1), with incubation under agitation (120 rpm) and non-agitation, totaling 8 experimental conditions. Biomass production was determined from the dry weight, while glucose consumption was estimated by quantification of reducing sugars. The proteins were extracted in NaCl (0.15 M), and the protein extracts were submitted to protein quantification by the Bradford method, total proteolytic activity using azocasein, caseinolytic and fibrinolytic activity in Petri dishes, activity of serine (trypsin and chymotrypsin) and cysteine (papain) protease inhibitors. Cultivation in agitated condition showed higher biomass production with a maximum value of 7 g.L-1, in addition to higher activities of trypsin, chymotrypsin and papain inhibitors, with 154 IU.mg-1, 153 IU.mg-1 e 343 IU.mg-1 of protein, respectively. The non-agitated condition showed a greater potential for obtaining proteins, total proteases, caseinolytic and fibrinolytic enzymes, with maximum values of 433 mg.g-1 of extract, 71 U.mL-1 of extract, 63.62 mm2 and 50.27 mm2, respectively. Thus, a medium composed of soy peptone, yest extract and glucose in a 1:2:4 proportion is recommended, under agitation to produce protease inhibitors, and the non-agitated condition when the target is, mainly caseinolytic and fibrinolytic enzymes.

Oxygen mass transfer enhancement by activated carbon particles in xylose fermentation media.

In this work, the effect of activated carbon particles on the production of xylonic acid from xylose by Gluconobacter oxydans in a stirred tank bioreactor was investigated. The enhancement of the oxygen transfer coefficient by activated carbon particles was experimentally evaluated under different solids volume fractions, agitation and aeration rates conditions. The experimental conditions optimized by response surface methodology (agitation speed 800rpm, aeration rate 7 L min-1, and activated carbon 0.002%) showed a maximum oxygen transfer coefficient of 520.7h-1, 40.4% higher than the control runs without activated carbon particles. Under the maximum oxygen transfer coefficient condition, the xylonic acid titer reached 108.2g/L with a volumetric productivity of 13.53g L-1h-1 and a specific productivity of 6.52g/gx/h. In conclusion, the addition of activated carbon particles effectively enhanced the oxygen mass transfer rate. These results demonstrate that activated carbon particles enhanced cultivation for xylonic acid production an inexpensive and attractive alternative.

Continuous long-term glucose biosensor in agitation condition for bioconversion processes

The use of a glucose biosensor in the bioconversion processes is challenging due to a long period of intensive stirring that is required to mix the heterogenous substants together. In this work, a glucose biosensor was developed to be accurate and robust for an extended period of measuring time in agitated conditions. The sensor probe was fabricated by electro-polymerization of polyaniline (PANI) nanostructures on a gold wire before putting in gold nanoparticles (AuNPs) and carrageenan (carr) solution to make an PANI-carr-AuNPs layer. Then the probe was soaked in PQQ-Glucose dehydrogenase (GDH) solution before coating with polyurethane (PU) to prevent the enzymes from leaching away from the sensor. The sensor probe showed a sensitivity of 0.85 μA/mg/ml of glucose with R2 of 0.9973. The storage stability of the probe was up to 4 days with stable signal. In agitated condition of 150 rpm, steady signals from the sensor were continuously obtained for 72 h. In sugarcane bagasse hydrolysis with speed at 150 rpm for 72 h, the biosensor continuously displayed signals which were not significantly different in glucose concentration to the results from the HPLC method. This biosensor displayed promising applications in bioconversion processes.

Impact of different nitrogen amendments on the biodegradation of 14C-phenanthrene by endophytic fungal strains in liquid culture

In this study, the biodegradation of phenanthrene was investigated in newly isolated endophytic fungal strains, Fusarium sp. (KTS01), Trichoderma harzianum (LAN03), Fusarium oxysporum (KTS02), Fusarium oxysporum (LAN04), and Clonostachys rosea (KTS05). This was performed under different carbon:nitrogen ratios (10:1, 20:1, and 30:1) using different nitrogen sources (urea and malt extract and ammonium nitrate) over a 30 d incubation period in both static and agitated liquid media. The kinetics of polycyclic aromatic hydrocarbons (PAH) mineralisation to CO2 (lag phases, fastest rates, and overall extents) were measured for all of the fungal strains and nutrient conditions using 14C-phenanthrene. All fungal strains were able to biodegrade 14C-phenanthrene to 14CO2 under the different nutrient amendments. However, 14C-phenanthrene mineralisation varied for most of the fungal strains in static and agitated culture conditions. Greater extents of mineralisation were found in fungal cultures (strains KTS05 and KTS01) with C:N ratio of 10:1 in both static and agitated conditions, while the fungal strains (KTS05 and LAN03) showed the greatest phenanthrene mineralisation after N source amendments, particularly with malt extract. In addition, the phenanthrene mineralisation increased with higher C:N ratios for Clonostachys rosea (KTS05) only. Consequently, the results reported here provide a promising potential for the endophytic fungal strains and the importance of nutrients amendments for the enhanced degradation of PAHs contaminated environments.

Novolac-based microcapsules containing isocyanate reagents for self-healing applications

Microcapsules (MCs) containing isocyanate compounds for use as self-healing materials in waterborne polyurethane coatings have been synthesized, in the presence of modified Novolac resins. With modification of Novolac resin, it is succeeded partial or total protection (Benzylation and Acetylation) of its hydroxyl groups. The idea here is to use a protected Novolac resin as the organic substrate for the encapsulation of the less reactive Isophorone isocyanate (IPDI) while the more reactive one, Methylene diphenyl diisocyanate (MDI), is used for the shell formation. Based on that strategy microcapsules of different morphologies and sizes were obtained, depending on the agitation conditions, as revealed using SEM and optical microscopy. Selective extraction was performed to determine the amount of the less reactive isocyanate (IPDI) stored inside the capsules through FTIR-ATR spectroscopy and isocyanate titration as well as the stability of IPDI inside the capsules over time. As determined, microcapsules based on Acetyl-modified Novolac resin encapsulated 96 wt% of IPDI monomer; this amount is about five and ten times higher than that encapsulated in MCs based on by Benzyl-modified Novolac resin or unprotected Novolac resin, respectively. At the same time, MCs based on Acetyl-modified Novolac resin were stable, maintaining approximately 80 % of the initial isocyanate content after two months of storage under inert conditions. Finally, the self-healing ability of the microcapsules was tested by adding selected IPDI-loaded microcapsules in waterborne polyurethane dispersions. It was proven that the Acetyl-modified Novolac-based MCs showed efficient healing behavior, in the absence of any catalyst, on the polyurethanes’ surfaces when scratched artificially.

Effects of chemical potential differences on methane hydrate formation kinetics

To underpin the increasing interest in practical applications of gas hydrates, for gas storage and separation for instance, the formation and growth of hydrates at liquid-gas interfaces are of fundamental importance. Although the thermodynamics of hydrate formation has been widely studied and is well understood, the kinetics of these processes is not well characterised. In this work, a high-pressure, low-temperature stirred reactor was used to conduct hydrate formation kinetic studies in a temperature range from 276.5 to 283.5 K and a pressure range from 5 to 10.5 MPa, with a special focus on 1) the impact of agitation conditions on the available water-gas interfacial surface area for mass transfer and growth rate during hydrate formation, and 2) the effect of the chemical potential driving force on the formation rate. Five hydrate growth regimes were identified, with varying degrees of gas mass transfer control across the gas-water interface depending on the extent to which hydrate layers built up at this interface, gas needed to move through solid hydrate layers, and the extent to which the gas was entrained within the water phase. The formation rate in the initial linear growth regime, before the onset of solid hydrate gas mass transfer effects, was found to depend in an essentially exponential manner on the chemical potential difference from the equilibrium state. Semi-empirical models related to Arrhenius-type kinetic models were used to correlate the data, the best of which reproduced the formation rates from the chemical potential differences to within ± 5 %. The approach has general applicability to help determine the balance between kinetic and thermodynamic factors in identifying the optimum pressure-temperature conditions for processes for gas storage, gas separation and other hydrate applications.

Improving methane production from food waste by intermittent agitation: Effect of different agitation frequencies on solubilization, acidogenesis, and methanogenesis

The intermittent agitation system is effective in reducing energy consumption during anaerobic digestion of organic waste. However, insufficient agitation leads to a significant reduction in reactor performance. Therefore, it is necessary to clarify the organic degradation reactions that are limited or accelerated by agitation to ensure proper agitation. This study aimed to investigate the effects of different agitation frequencies on solubilization, acidogenesis, and methanogenesis. Food waste, which is a relatively easily degradable and common substrate for anaerobic digestion, was treated in a mesophilic batch operation under continuous, intermittent (15 min every 6, 12, and 24 h), or no agitation conditions. The highest cumulative CH4 yield of 339 NmL g-COD−1 was obtained under intermittent agitation once every 12 h, followed by 306 and 304 NmL g-COD−1 under continuous agitation and once per 6 h agitation, respectively. However, lower agitation conditions (once per 24 h and no agitation) showed lower methane yields. Based on the mass balance of chemical oxygen demand, the solubilization efficiency tended to be high under high agitation frequency. Furthermore, the highest acidogenesis and methanogenesis efficiencies were obtained under once per 12 h agitation. The number of microbial cells and the relative abundance of hydrogenotrophic methanogens that work with H2 producing bacteria decreased, likely due to agitation stress. A once per 12 h agitation was sufficient to promote solubilization and avoid agitation stress on microorganisms in the food waste treatment. Moderate intermittent agitation is a promising method for maximizing CH4 recovery and minimizing energy consumption.

ZnO Nano-swirlings for Azo Dye AR183 photocatalytic degradation and antimycotic activity

The sol-gel technique was used to fabricate ZnO Nano-swirlings (ZNsw) at a predetermined agitation rate (of >> 1900 rpm), with around 21.94 gm of zinc acetate dihydrate and 0.2 g cetyltrimethylammoniumbromide (CTAB) and a cationic surfactant (drop-wise). The impact of the predetermined agitation condition on the molecular size and morphology of ZNsw is examined, and the outcomes are dissected by useful characterization tools and techniques viz. XRD, SEM embedded with EDS, TEM, FT-IR and UV–visible. The SEM and TEM results suggest that the product formed into a big cluster of adequate ZNsw, containing a significant quantity of folded long thread-lengths. Each group indicated a fair amount of the volume of these lengths. The photocatalytic process of ZNsw was carried out as a result of the irradiation time due to the deterioration of Azo Dye AR183, resulting in approximately 79 percent dye discoloration following an 80-min UV light irradiation in the presence of ZNsw. Additionally, the synthesized ZNsw was tested for antagonistic activity, and the growth hindrance of two plant pathogenic fungal strains found. Per cent inhibition in growth of Rhizoctonia solani and Alternaria alternata were observed in response to ZNsw.

A model predictive control (MPC)-integrated multiphase immersed boundary (IB) framework for simulating wave energy converters (WECs)

In this work, we present a novel MPC-integrated multiphase IB framework that can compute the optimal energy-maximizing control force “on-the-fly” by dynamically interacting with a high-fidelity numerical wave tank (NWT). The computational model closely mimics the working setup of the device at its site of operation. Due to the requirement of solving a constrained optimization problem at each time step of the IB simulation, the MPC algorithm utilizes a low-dimensional dynamical model of the device that is based on the linear potential theory (LPT). The multiphase IB solver, on the other hand, is based on the high-dimensional fictitious domain Brinkman penalization (FD/BP) method, which fully-resolves the hydrodynamic non-linearities associated with the wave–structure interaction (WSI). A time-series forecasting auto-regressive model is implemented that predicts wave heights (from the past NWT data) to estimate the future wave excitation/Froude–Krylov forces for the MPC algorithm. Moreover, we also experiment with non-linear Froude–Krylov (NLFK) forces for the first time in an MPC formulation. The NLFK forces are computed efficiently using a static Cartesian grid, in which the WEC geometry is implicitly represented by a signed distance function. Under varying sea conditions, the predictions of the MPC-integrated multiphase IB solver are compared to the widely popular LPT-based solvers. In agitated sea conditions and/or under aggressive control, the LPT-based WSI solvers produce too optimistic (and misleading) power output values. Overall, six WSI/MPC solver combinations are compared for a heaving vertical cylinder to determine the reasons for discrepancies between high- and low-fidelity predictions. We also determine the pathway of energy transfer from the waves to the power take-off (PTO) system and verify the relationships using IB simulations. Additionally, three different sea states are simulated within the IB simulation to test the adaptive capability of MPC for WECs. MPC is demonstrated to adapt to changing sea conditions and find the optimal solution for each sea state.The interaction between the distributed-memory parallel multiphase IB solver (written in C++) and the serial MPC solver (written in MATLAB) is fully described to facilitate reproducibility. A bespoke communication layer between the two solvers is developed, which can be easily modified by the WEC community to experiment with other optimal controllers and computational fluid dynamics (CFD) solvers. All codes for this work are made open-source for pedagogical and research purposes.

Exploring Strategies to Reduce Falls and the Role of Simulated Presence for the Elderly Patients with Cognitive Issues in Isolation Rooms

The COVID pandemic has caused disruptions in people’s lives and presents an unprecedented challenge on the health care systems. Isolating elderly with cognitive impairment worsens functional independence, leading to falls, use of restraints, and worsening of behavioural symptoms such as agitation, superimposed delirium, depression, and health condition due to unfamiliar environment and absence of their usual caregivers. Interventions to reduce falls in isolation rooms with negative pressure were possible, despite the restrictions. Various methods to keep the patients cognitively and socially engaged using iPads showed good results with improvement in mood, reduction in agitation and improved engagement among the patients and the staff.

Mycelial Growth-promoting Potential of Extracellular Metabolites of Paraburkholderia spp. Isolated from Rhizopogon roseolus Sporocarp

This study aimed to investigate the effect of potential metabolite(s) produced by Paraburkholderia spp. isolated from the Rhizopogon roseolus (shouro mushroom) sporocarp on the mycelial growth of R. roseolus. For this purpose, we selected two molecularly identified bacteria: P. fungorum GIB024 and P. caledonica KN1. Direct confrontation assay at three different distances, a pour plate method that sampled bacterial spent broth either with and without agitation at 25 °C, and an indirect confrontation assay was carried out in order to assess the R. roseolus growth-promoting ability of Paraburkholderia spp. These assessments were carried out in a 1:5 diluted Melin-Norkran-modified medium with glucose (hs-dMMN) and without glucose (ls-dMMN). GIB024 promoted the growth of R. roseolus in ls-dMMN in short distance, whereas KN1 inhibited the growth of the fungus in that condition. In hs-dMMN, both bacteria have neutral or slightly promotion effect toward R. roseolus. We determined from the spent broth analysis that Paraburkholderia spp. that grew axenically under static conditions had a more pronounced mycelial growth-promoting effect on R. roseolus than under agitation conditions. We also found that high concentration of spent broth resulted in a decrease in mycelial growth-promoting ability. Volatile metabolite(s) produced by both bacteria did not promote the mycelial growth of R. roseolus. In conclusion, Paraburkholderia spp. exhibited a species- and nutrient (sugar)-dependent ability to promote the mycelial growth of R. roseolus, and the bacterial soluble metabolite(s) play a crucial role in their growth-promoting ability.

The Using of Nanoparticles of Microalgae in Remediation of Toxic Dye from Industrial Wastewater: Kinetic and Isotherm Studies.

Batch adsorption experiments were carried out to study the removal of the toxic Methylene Blue Dye (MBD) from synthetic aqueous solutions using the nanoparticles form of Arthrospira platensis NIOF17/003. The adsorption capacity of the adsorbent for MBD was investigated using different amounts of A. platensis nanoparticles at different contact times, temperatures, pH, and MBD initial concentrations in the synthetic aqueous solution. In addition, A. platensis nanoparticles were characterized using Electron Microscopy (SEM), Brunauer–Emmett–Teller (BET), Fourier Transform Infrared (FTIR), and Ultraviolet spectra (UV) techniques. The optimum removal of MBD was found at a concentration of 0.4 g A. platensis nanoparticles. A. platensis nanoparticles remove 93% of MBD in 5 min (under agitation conditions at 150 rpm). The highest adsorption capacity was found by the Langmuir model to be 58.8 mg g−1. It is an endothermic process with spontaneity increasing with temperature. The probable mechanism for the adsorption is chemisorption via surface-active charges in the initial phase, which is followed by physical sorption by occupying pores of A. platensis. MBD adsorption by A. platensis follows pseudo-second-order kinetics. The Freundlich and Langmuir models fit well with the experimental data. The adsorption experiments suggested that the regeneration of the adsorbents was possible for repeated use, especially regarding MBD up to 65.8% after three cycles, which proves it can be easily recycled. In conclusion, the nanoparticles of A. platensis have a significant adsorption potential in the removal of MBD from effluent wastewater.

The influence of dexmedetomidine on the emergence agitation of pediatric patients after the operations of sense organs under general anesthesia using sevoflurane.

We investigated the influence of dexmedetomidine on the emergence agitation of pediatric patients after ophthalmologic operation under general anesthesia using sevoflurane. We selected 90 patients that were administered pediatric ophthalmologic operation for the study. The patients were randomly divided into 3 groups according to the administration way of drugs, i.e. the normal saline group (group S, N.=30), the midazolam group (group M, N.=30) and the dexmedetomidine group (group D, N.=30). For all patients, anesthesia induction was performed using sevoflurane before anesthesia, and the anesthesia was maintained in the operation with a combination of sevoflurane and remifentanil; laryngeal mask airway (LMA) was used for assisted ventilation. Ten minutes before the end of operation, 15 mL of 0.9% normal saline, 0.05 mg/kg of midazolam and 0.5 μg/kg of dexmedetomidine were administered to group S, group M and group D, respectively. After the operation, we observed the awakening time, time of the LMA removal as well as the recovery time in the Post Anesthesia Care Unit (PACU) of patients in all three groups. We evaluated the postoperative condition of sedation and agitation of the patients using Ramsay Sedation Scale, 5-point scale and Pediatric Anesthesia Emergence Deliriums Scale (PAED) and performed statistical analysis. In the comparisons of awakening time, time of the LMA removal as well as the recovery time, we found that group M was the longest sequentially followed by group D and group S with statistically significant differences (P<0.05). While the comparison of the scores of Ramsay Sedation Scale revealed that group D scored highest followed by group M and group S with statistically significant differences (P<0.05), both of the comparisons of the scores of 5-point scale and PAED Scale showed that group D scored the lowest, followed by group M and group S in sequence with statistically significant differences (P<0.05). Dexmedetomidine can significantly lower the incidence of emergence agitation of pediatric patients after the ophthalmologic operation under sevoflurane anesthesia.

유액흐름 분석을 통한 바이오 폴리머 생산 효모의 교반조건 최적화

The medium used for microbial fermentation is generally in a liquid state, that is, a fluid. Here, there is no fixed shape, and the flow is irregular. Attempts have been made to analyze and predict the flow of the fluid. Kluyveromyces marxianus JMA-1 was developed to produce 3-hydroxy propionic acid (3-HP), a biopolymer precursor, and the agitation conditions were optimized by applying hydrodynamics. The maximum flow velocity and Γ1 value indicating the degree of rotation were the highest (45.35 ㎝/s and 0.72, respectively) in the control (Baffle 0) and the lowest (20.99 ㎝/s and 0.40, respectively) in Baffle 2. However, 3-HP production was the highest (8.82 ± 0.24 g/L) in Baffle 2 and the lowest (6.83 ± 0.11 g/L) in the control. The 3-HP production of Baffle 2 improved by 29% compared to that of the control.

Gelation and anomalous viscosity dynamics in aqueous dispersions of synthetic hectorite

Exfoliated clay nanosheets (CNSs) of synthetic hectorite (s-hectorite) have been used for synthesizing advanced functional materials and gels that exhibit high transparency, high mechanical toughness, and many unprecedented characteristics like optical anisotropy, cell harvesting, instant strong adhesion, and self-healing. Therefore, it is important to determine the rheological properties of aqueous s-hectorite dispersions in terms of the CNS microstructures formed in the dispersion. Herein, viscosity changes in aqueous dispersions of s-hectorite were determined using a vibration viscometer to measure viscosity under agitated and static conditions. Upon varying the pH and salt concentration, aqueous dispersions of s-hectorite exhibited a maximum viscosity accompanied by gelation. Additionally, the aqueous dispersion with maximum viscosity exhibited large and complex time-dependent viscosity changes in the static state after cessation of stirring. The anomalous viscosity dynamics depended on the types of clay, acid (salt), temperature, repetitions, and agitation conditions used. The mechanisms for viscosity dynamics have been discussed in terms of variations in the CNS microstructures. It is inferred that anomalous viscosity dynamics are a general phenomenon in multicomponent dispersion systems containing CNSs.

Characterization of biosorption potential of Brevibacillus biomass isolated from contaminated water resources for removal of Pb (II) ions.

Various activities of different industries are found to be the main reason for water pollution with heavy metals. Use of microorganisms that are tolerant even of a high concentration of metal ions could be a valuable tool for remediation of contaminated water resources. In the present study, microorganisms that showed high resistance to lead ions were isolated and evaluated for biosorption efficiency for removal of lead ions from waste water. Biochemical identification and 16S rRNA gene sequence analysis indicated that the isolated strain was Brevibacillus. The conditions of pH, biomass concentration, temperature, time, agitation and Initial concentration of metal for biosorption of Pb (II) were optimized. Based on induction coupled plasma optical emission spectroscopy (ICP-OES) analysis, the biosorption efficiency of Brevibacillus at optimized conditions of initial metal concentration of 150 μg/mL, 1 g/L of biomass dose, pH 6.0, 40 °C, for 12 h at 80 rpm was 78.58% and the biosorption capacity (qe) is 128.58 mg/g of the biosorbent. Of the three isotherm models investigated, the Freundlich isotherm model was identified as a good fit with high correlation coefficient, while kinetic data followed the pseudo first order model as best fit. Surface characterization by scanning electron microscopy (SEM) analysis revealed morphological changes with a bulged rod-shape cell having metal depositions and rough texture. The presence of lead within the cell was detected by transmission emission microscopy (TEM). The key functional groups that participate in biosorption were analyzed by Fourier transform infrared (FTIR) spectroscopy and were found to be carboxyl, hydroxyl, amino and phosphate groups. From the real-time study, it proves that the biomass of Brevibacillus can be used as a promising biosorbent for removal of metals including lead from waste water.

Green and Controllable Preparation of Cu/Zn Alloys Using Combined Electrodeposition and Redox Replacement

This study outlines a novel and sustainable electrodeposition–redox replacement (EDRR) method to produce Cu/Zn alloys using a simulated hydrometallurgical Zn solution containing 200 ppm Cu, 65 g/L Zn, and 10 g/L H2SO4. The results indicate that by tailoring the EDRR parameters, like deposition time, replacement time, and agitation conditions, Cu/Zn alloys with controllable properties including chemical composition, microstructures, colorations, and crystalline phases can be readily obtained. Scanning electron microscopy (SEM) analysis shows that coherent Cu/Zn films grow from separate nanoscale particles produced during the initial EDRR cycles. Furthermore, the corrosion performance of the prepared Cu/Zn films is tunable by changing the crystalline phases through the variation of operating conditions. For example, deposits containing Zn-rich phases (CuZn5, Cu5Zn8) obtained with short redox replacement times without agitation resulted in relatively poor corrosion resistance. In contrast, Cu-rich phases (Cu0.75Zn0.25, Cu0.85Zn0.15) with enhanced corrosion performance were achieved with prolonged redox replacement times and/or the application of magnetic stirring. Unlike traditional electrodeposition, the EDRR method does not involve any complexing agents and the currently underutilized hydrometallurgical solutions were used as potential raw materials. Overall, the study suggests the EDRR method as a promising approach to achieve sustainable manufacturing of Cu/Zn alloys and an improved circular economy of metals.