The autonomic self-healing materials based on microcapsules have made major advancements for the repairing of microcracks in polymers and polymer composite systems. Self-healing encapsulated ...materials have the inborn ability to heal polymeric composites after being damaged by chemical and mechanical progressions. These intelligent micro-encapsulated self-healing materials possess great capabilities for recovering the mechanical as well aesthetic properties and barrier properties of the polymeric structures. Based on real world observations and experimental data, it is believed that microcracks and microcracking in polymeric materials can result because of many chemical and physical routes and is one of the foremost critical issues for polymeric materials. Especially in polymeric coatings, these microcracks can lead towards disastrous failure, and conventional healing systems like patching and welding cannot be used to repair microcracks at such a micro-level. Self-healing materials, especially, capsule based self-healing materials is a new field sought as an alternative to the conventional repairing techniques, requiring no manual intrusion and uncovering. This review covers the basic and major aspects of the microencapsulated self-healing approach like the effect of synthesis parameters on the size of microcapsules, healing efficiency determination, and the potential of the existing developed microencapsulated agents.
This research aims to treat wastewater that has been contaminated with one of the most prevalent toxic heavy metals, Cu
2+
. The thermal pyrolysis process was used to manufacture MgO nanoparticles. ...Spectroscopy, X-ray diffraction (XRD). The production of MgO nanoparticles was validated using X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDX). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) tests revealed spherical particles at the nanoscale (50 nm), with a BET surface area of 67 m
2
. g
−1
. The Cu
2+
adsorption process was fast and well represented by the pseudo-second-order kinetic and Langmuir models. With a regression coefficient of 0.9960, the Langmuir pattern achieved the highest adsorption capability of Cu
2+
: 546.45 mg/g. The MgO nanoparticles generated for Cu
2+
uptake are promising and could be used to eradicate other poisonous heavy metals in the aquatic media.
The effect of the exposure to thermo-switchable solvent (TSS) on cell wall disruption of
Chlorella
sp. microalgae was investigated. The combustion and kinetic behaviors of microalgae cells treated ...with TSS, which was maintained at its hydrophilic state for 1.5 h to disrupt the cell wall, were analyzed and compared with those of undisrupted cells. The X-ray diffraction (XRD) results showed a clear drop in the crystallinity of the TSS-treated samples, which was mainly due to the degradation of the cellulosic material. The results were confirmed from the thermogravimetric analysis, which showed a drop in the cellulosic material from 71.9% in the untreated sample to 49% for TSS-treated sample. The activation energy of TSS-treated sample from different non-isothermal models was 44.90–157.97 (FWO), 103.09–492.19 (KAS), and 100.60–478.89 kJ mol
−1
(Starink). The values were lower at low conversions (x ≤ 0.5) than untreated samples whose activation energy was 70.67–152.98 (FWO), 195.38–465.58 (KAS), and 190.39–453.11 kJ mol
−1
(Starink). The low activation energies for all models of TSS-treated samples indicate that less energy would be required for the thermal conversion processes, as compared with the untreated samples. The tested model-free methods reduce mass transfer limitations, with Flynn-Wall-Ozawa (FWO) compensating for experimental errors, whereas Kissinger-Akahira-Sunose (KAS) and Starink for providing precision to kinetic data depending on a good constant degree of conversion. The reaction mechanism was represented well by the Malek and Popescu. The results presented in this work provide deeper understanding of the effect of TSS on microalgae cell wall disruption.
Removing toxic metal ions arising from contaminated wastewaters caused by industrial effluents with a cost-effective method tackles a serious concern worldwide. The adsorption process onto metal ...oxide and carbon-based materials offers one of the most efficient technologies adopted for metal ion removal. In this study, mesoporous MgO/g-C3N4 sorbent is fabricated by ultrasonication method for the uptake Pb (II) and Cd (II) heavy metal ions from an aqueous solution. The optimum conditions for maximum uptake: initial concentration of metal ions 250 mg g−1, pH = 5 and pH = 3 for Pb++ and Cd++, and a 60 mg dose of adsorbent. In less than 50 min, the equilibrium is reached with a good adsorption capacity of 114 and 90 mg g−1 corresponding to Pb++ and Cd++, respectively. Moreover, the adsorption isotherm models fit well with the Langmuir isotherm, while the kinetics model fitting study manifest a perfect fit with the pseudo-second order. The as fabricated mesoporous MgO/g-C3N4 sorbent exhibit excellent Pb++ and Cd++ ions uptake and can be utilized as a potential adsorbent in wastewater purification.
In this study, quaternary MgY2O5@g-C3N4 nanomaterials were produced using a simplistic ultrasonic power technique in the presence of an organic solvent, and their capability to abolish Cu (II) from ...an aqueous solution was evaluated. As validated by powder X-ray diffraction, the synthesized nanomaterials possessed excellent crystallinity, purity, and tiny crystalline size. According to BET and TEM, the nanomaterials with high porosity nanosheets and perfect active sites made Cu (II) removal from water treatment feasible. At a pH of 3.0, the MgY2O5@g-C3N4 displayed good Cu (II) adsorption capability. The Cu (II) adsorption adhered to the Langmuir adsorption model, with an estimated theoretical maximum adsorption aptitude of 290 mg/g. According to the kinetics investigation, the adsorption pattern best fitted the pseudo-second-order kinetics model. Depending on the FTIR results of the nanocomposite prior to and after Cu (II) uptake, surface complexation and ion exchange of Cu (II) ions with surface hydroxyl groups dominated the adsorption of Cu (II). The MgY2O5@g-C3N4 nanomaterials have great potential as adsorbents for Cu (II) removal due to their easy manufacturing process and high adsorption capacity. Additionally, the reuse of MgY2O4@g-C3N4 nanomaterials was tested through the succession of four adsorption cycles using HNO3. The result showed the good stability of this material for mineral pollution removal.
Ru-ZnO-g-C3N4 nanocomposite was made using a straightforward ultrasonication method and evaluated for its potential to remove Cd ions from aqueous environments. X-ray diffraction analysis confirms ...composite production with an average crystalline size of 6.61 nm, while transmission electron microscopy results indicate nanosheet-like nanomaterials with uniform elements distribution. Measurements of N2 adsorption–desorption reveal the creation of a mesoporous structure with a BET surface area of approximately 257 m2/g. Fourier converted infrared reveals vibrational modes for O-H, amino groups, triazine, and Ru-ZnO. In contrast, X-ray photoelectron spectroscopy investigation reveals the presence of the elements Ru, Zn, O, N, and C. Ru-ZnO-g-C3N4 nanocomposite has remarkable adsorption efficiency for aqueous Cd ions, achieving 475.5 mg/g in 18 min. This study reveals that the Ru-ZnO-g-C3N4 nanocomposite may be used as an effective and reusable adsorbent for removing Cd ions during wastewater treatment and, possibly, for eliminating other toxic metal ions.
Elimination of heavy metals from contaminated water systems is of prime distress due to their capacity to prompt toxic impact on the flora and fauna. The usage of innovative nano-engineered materials ...predominantly opens up smart prospects for the treatment of persistent heavy metal adulterated water resources. This study presents an ultrasonic-assisted sol-gel production of Ru@Co3O4@g-C3N4 nanostructure that was utilized to remove Cu+2 and Cd+2 ions from aqueous solutions. The X-ray diffraction investigation revealed the development of RuO2, Co2O3 and g-C3N4 phases, and the relevant elemental composition was verified by the photoelectron spectroscopy and EDX. The dispersion of the metal oxides within the nitride sheets was evidenced by scanning and transmission electron microscopy. The initial metal ions concentration, pH, and contact time effects were investigated through batch experiments. The adsorption isotherm models matched the Langmuir isotherm well, whereas the kinetics model data perfectly fitted the pseudo-second-order model. The maximum adsorption capacities of Cu+2 and Cd+2 ions on the nanocomposite Ru@Co3O4@g-C3N4 were 696.9 and 564.5 mg/g, respectively. A mechanism based on a viable covalent type of bonding developed by the delocalized -conjugated electrons of the triazine ring and functional groups were efficiently involved in the metal ions anchoring and ultimate elimination. Thus, the suitability of the Ru@Co3O4@g-C3N4 nanocomposite for eradicating heavy metals, including Cu+2 and Cd+2, was established.
Herbal medicine is a medical system based on the utilization of plants or plant extracts for therapy. The continual increase in global consumption and the trade of herbal medicine has raised safety ...concerns in many regions. These concerns are mainly linked to microbial contamination, which could spread infections with multi-resistant bacteria in the community, and heavy metal contamination that may lead to cancers or internal organs' toxicity.
This study was performed using an experimental design. A total of 47 samples, herbal medicine products sold in local stores in Qassim region, were used in the experiments. They were tested for bacterial contamination, alongside 32 samples for heavy metal analysis. Bacterial contamination was determined by the streak plate method and further processed to determine their antimicrobial susceptibility patterns using MicroScan WalkAway96 pulse; heavy metals were determined using a spectrometer instrument.
A total of 58 microorganisms were isolated. All samples were found to be contaminated with at least one organism except three samples. The majority of the isolated bacterial species were gram negative bacteria, such as Klebsiella spp., Pseudomonas spp. and E. coli., which could be of fecal origin and may lead to pneumonia, skin, or internal infections. Furthermore, most of the gram-positive bacteria were found to be multi-drug resistant. Moreover, for heavy metals, all samples had levels exceeding the regulatory limits.
This study demonstrated the presence of bacteria and heavy metals in samples of herbal medicines. Using these contaminated products may spread resistant infections, metal toxicities, or even cancers in the community.
A thermo-responsive switchable solvent (TSS), which switched hydrophobicity by the change in temperature, was successfully used for simultaneous cell disruption, oil extraction-reaction, and ...biodiesel separation from wet microalgae. Catalyzed by immobilized lipase, the entire process was carried out in a single pot using the same solvent without drying the microalgae. Besides being easier to operate, the biodiesel yield using the TSS was 21% higher than that achieved using CO2-triggered switchable solvent under the same conditions and solvent switching program. To optimize the process, a parametric study was performed to evaluate the effects of cell disruption and extraction/reaction durations and methanol amount on the biodiesel production yield. The results were used to develop a statistical model to predict the biodiesel yield under different conditions. The model was validated by repeating the reaction as defined by the model and a yield of 75.11 ± 1.03% was observed. Moreover, we observed that the immobilized enzyme retained its activity till two rounds of reaction, and future optimization may improve the reusability further. In conclusion, our results showed that the successful use of a TSS lipids extraction-reaction from wet biomass can significantly simplify the biodiesel production from wet microalgae.
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•Using Switchable Solvents (SS) simplifies biodiesel production process.•Thermo-responsive SS was successfully used for direct biodiesel production from wet undisrupted microalgae.•Thermo-responsive SS showed higher FAMEs yield compared to the CO2 triggered SS.•Thermo-responsive SS–enzyme system has the potential for enhanced reusability.
Individuals and corporate users are persistently considering cloud adoption due to its significant benefits compared to traditional computing environments. The data and applications in the cloud are ...stored in an environment that is separated, managed and maintained externally to the organisation. Therefore, it is essential for cloud providers to demonstrate and implement adequate security practices to protect the data and processes put under their stewardship. Security transparency in the cloud is likely to become the core theme that underpins the systematic disclosure of security designs and practices that enhance customer confidence in using cloud service and deployment models. In this paper, we present a framework that enables a detailed analysis of security transparency for cloud based systems. In particular, we consider security transparency from three different levels of abstraction, i.e., conceptual, organisation and technical levels, and identify the relevant concepts within these levels. This allows us to provide an elaboration of the essential concepts at the core of transparency and analyse the means for implementing them from a technical perspective. Finally, an example from a real world migration context is given to provide a solid discussion on the applicability of the proposed framework.
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