Irradiation Time Research Articles

The Photodynamic Antibacterial Activity Properties of a Series of Indium(III) Porphyrins and their Gold and Silver Nanoparticle Conjugates

AbstractIn(III) tetraarylporphyrin complexes with 4‐thiomethylphenyl (1‐InPor), thien‐3‐yl (2‐InPor), thien‐2‐yl (3‐InPor) and 5‐bromothien‐2‐yl (4‐InPor) meso‐aryl rings have been synthesized and characterized. The complexes have been conjugated to gold and silver nanoparticles (AuNPs and AgNPs). The photodynamic antimicrobial chemotherapy (PACT) activities of 1–4‐InPor and their AuNP and AgNP conjugates have been investigated against both planktonic bacteria and biofilms of Gram‐(+) S. aureus and Gram‐(−) E. coli. 2.5 μg.mL−1 solutions of 1–4‐InPor exhibited favorable PACT activities against planktonic S. aureus with high Log10 reduction values in the 4.28–7.69 range upon 75 min photoirradiation with a Thorlabs M625L3 LED (240 mW.cm−2) mounted onto the illumination chamber of a Modulight 7710 medical laser system to provide a dose at the well‐plate of 86 mJ.cm−2.min−1. In contrast, low values in the 1.4–1.9 range were obtained against E. coli with 10 μg.mL−1 solutions. 1–4‐InPor exhibited relatively low PACT activity against the biofilm cells of S. aureus and E. coli. Conjugation of 1–4‐InPor to AgNPs and AuNPs significantly enhanced the PACT activities. This is demonstrated by the complete eradication of planktonic S. aureus at shorter irradiation times with high Log10 values>7.69 and moderate Log10 values>2 against planktonic E. coli for the meso‐thienylporphyrin conjugates.

Phenomenological toy model for flash effect in proton therapy

We present a simple model based on general assumptions for the FLASH effect in radiotherapy, leading to a rate equation with only three free parameters. The model can predict the biological effect ratio between healthy and tumoral tissue for arbitrary input treatments, given as a dose rate versus time function. We analyze the behavior of the model and its sensitivity to its free parameters, and decide on suitable parameter values in accordance with available experimental data from the literature. Then we apply our model to study different sets of treatments, modeled as square pulse periodic functions with different pulse peak dose rate, pulse width and repetition period, in order to illustrate how it may be used to guide future experiment design. The model predicts that, for a given average dose rate above the FLASH threshold, a more prominent FLASH effect would be observed for continuous beams than for ultra-pulsated beams with an infinitely short irradiation time. This finding needs to be validated with suitable experiments.

Moving Meniscus-Assisted Template-Free Optothermofluidic Nanoparticle Patterning and Its Application in Optothermoconvective Particle Trapping.

Moving meniscus-assisted vertical lifting is a commonly employed particle assembly technique to realize large-area particle patterning for the easy fabrication of colloidal photonic crystals and sensors. Though great success has been achieved for large-area patterning, inscribing desired patterns over the target substrate with precise control over the morphology remains a challenge. The target substrates need to be functionalized (physically or chemically) to realize desired patterns, which increases the complexity and limits their applicability to specific particle-liquid combinations. We demonstrate a new approach for the precise patterning of gold nanoparticles (Au NPs, diameter ∼60 nm) over solid substrates by the synergy of light-induced Marangoni flow and vertical lifting process (moving meniscus), without the requirement of photomasks or templates. The core idea relies on the particle accumulation due to light-induced Marangoni flow near the liquid meniscus in contact with a solid surface (due to plasmonic absorption of the particles) and the controlled lifting of the substrate. We present both the simulation and experimental results of the developed patterning technique. Various patterns such as continuous lines, intermittent lines with varying lengths, patterns with continuously varying widths, cross patterns, etc. are successfully inscribed. Dynamic control over the three-dimensional morphology of the deposited patterns is achieved by varying the lifting velocity, laser irradiation time, and lifting direction during the inscription process. Finally, we show the applicability of the developed plasmonically active surface for the large-area parallel manipulation of nonabsorbing microparticles based on optothermoconvective flow. The major advantage of the developed method compared to the existing light-controlled patterning techniques is its ability to inscribe patterns over large distances (up to several centimeters). We expect that the results presented in this paper will benefit different applications requiring precise particle patterning, such as optical elements, sensors, plasmonic substrates, microfluidic master templates, and electronic circuits.

Efficient microwave regeneration of iron-modified Na-based montmorillonite and Na-based attapulgite for enhanced adsorption of tetracycline in water

A novel iron-modified Na-based montmorillonite (Fe-MT) or iron-modified Na-based attapulgite (Fe-AT) adsorbent is successfully prepared using ion exchange method and applied to remove tetracycline (TC) in water, and the spent adsorbents saturated with organic pollutants are regenerated under microwave (MW) irradiation. The influences of the ratio of Fe3+ and cation exchange capacity, adsorption time, adsorbent dosage, MW power, and irradiation time are investigated. The possible adsorption and MW regeneration mechanism is also proposed. The results indicate that Fe-MT and Fe-AT have enhanced interlayer spacing and surface area after the Na-based montmorillonite (Na-MT) or Na-based attapulgite (Na-AT) are modified using Fe3+. 97.70 % and 95.04 % adsorption are obtained using Fe-MT and Fe-AT within 30.0 min at 298 K, respectively, while 78.54 % and 61.92 % adsorption are obtained using Na-MT and Na-AT, respectively. Also, the adsorption processes fit well with pseudo-second-order reaction kinetic and Freundlich model, signifying chemical and multilayered adsorption. The adsorption of TC using the above four adsorbents are spontaneous and endothermic. Moreover, MW regeneration can enhance the adsorption capacity of Fe-MT or Fe-AT, and the regeneration ratios can reach 98.82 % and 93.14 % under 800 W MW within 5.0 min, respectively. By comparison, the adsorption capacity, regeneration performance and reusability of Fe-MT with larger interlayer spacing and surface area are superior to that of Fe-AT. Therefore, this work provides new perspectives on the adsorption technique using modified clay minerals as adsorbents for dealing antibiotics in water and wastewater, and the MW regeneration technology for regenerating spent adsorbents saturated with organic pollutants.

The structural and optical properties of PVA/CMC copolymer cured by UV irradiation for different times

Poly(vinyl alcohol) (PVA)/carboxymethylcellulose (CMC) blend films with equal amounts (0.25 g) of both polymers were prepared through a simple and low-cost comparative casting method. Then, the PVA/CMC blend films were exposed to ultraviolet (UV) radiation for varied time intervals (1, 12, 26, 32, 40 and 48 h). The UV-irradiation effect on the physical properties of as-prepared films, including the structure, morphology, composite and optical properties (transmittance, absorbance and band gap (E g)), was examined. Field-emission scanning electron microscopy images showed that UV irradiation had a strong effect on the shape of PVA/CMC blend films. The X-ray diffraction patterns showed various crystalline qualities in the microstructure of as-synthesized samples. The Fourier transform infrared spectra showed that the UV-irradiation time and CMC film had a positive impact on the blend polymer structure since covalent connections were formed between CMC and PVA. Furthermore, the analysis results of optical inspections showed that the absorbance of the PVA/CMC films improved with an increment in irradiation time from 1 to 40 h. Important tuning of the E g values of blend films was realized. It showed a slight increase from 4.64 to 4.84 eV with increasing irradiation time from 1 to 40 h. The E g value (3.21 eV), however, displayed an inverted behavior due to an increased irradiation time of 48 h. This reduction could be ascribed to the creation of defects inside the blend band gap. Finally, the physical property modification of PVA/CMC blend film using UV irradiation made it an amazing contender in the optoelectronic field.

Assessment of visible light sensitive La-doped BiOBr/ZnO for the effective degradation of malachite green dye

Environmental scientists across the globe are actively focused on developing novel materials to remove hazardous wastes from aqueous environments. Among the several methods available, photocatalysis stands out as a very efficient and environmentally beneficial process for removing organic dyes from wastewater. The present work involved the successful fabrication of lanthanum-doped bismuth oxy bromide/zinc oxide (La-doped BiOBr/ZnO, LBZ) as a photocatalyst through a facile hydrothermal technique. The synthesized LBZ composite exhibited enhanced photocatalytic degradation efficiency towards the malachite green (MG) dye molecules under visible light. The synthesized materials were characterized by different analytical techniques like FTIR, XRD, SEM, EDX, XPS, LC-MS, UV–Vis DRS, PL spectra, and mapping analysis, respectively. Various contributing factors, including irradiation time, solution pH, catalyst dosage, and initial dye concentration, were optimized using the batch mode for the maximum efficiency of the prepared catalyst. The prepared LBZ exhibited a bandgap energy of 2.78 eV as determined through UV–Vis DRS analysis. Among the prepared series of catalysts, the LBZ composite could degrade 99 % MG with a minimum irradiation time of 50 min under visible light irradiation. The involvement of h+ and O2− radicals proved to be significant during the degradation process of MG. Additionally, a proposed mechanism for the effective degradation of the photocatalytic degradation of MG was discussed, and successfully identified the mechanism pathway of MG was by employing LC-MS analysis. This investigation highlights the potential of prepared LBZ composite as an effective photocatalyst for removing toxic dye molecules commonly present in industrial effluents.

Laser ablation mechanism and performance of glass fiber-reinforced phenolic composites: An experimental study and dual-scale modelling

Both experimental and simulation approaches were employed to investigate the laser ablation mechanism and performances of Glass Fiber Reinforced Phenolic Composites (GFRP). During the ablation process, the difference in thermal conductivities of the glass fibers and the resin matrix as well as their discrepant physical and chemical reactions form a conical ablation morphology. The formation of a residual carbon layer effectively mitigates the ablation rate in the thickness direction. A higher power density results in a faster ablation rate, while a longer irradiation time leads to a larger ablation pit diameter. To account for the variation in thermal conductivity between the fiber and resin, a macro-mesoscale model was developed to differentiate the matrix from the fiber components. Finite element analysis revealed that laser irradiation leads to phenolic decomposition, glass fiber melting vaporization, and residual carbon skeleton evaporation. The dual-scale model exhibits precise prediction capabilities concerning the laser ablation process of GFRP, and its accuracy is confirmed through the comparison of simulation and experimental results for the GFRP laser ablation process. This model provides a feasible method for performance evaluation and lifetime prediction of GFRP subjected to continuous wave laser irradiation.

Radiation resistant metal–organic frameworks for the production of high specific activity 51Cr by the Szilard-Chalmers effect

Chromium-51 (51Cr) is an attractive radionuclide for diagnosis, which is usually applied for red cells and platelet radiolabeling. However, commercially available 51Cr produced in nuclear reactors via neutron activation requires long irradiation times and complex separation methods. In this work, five metal–organic frameworks (MIL-100 (Cr), MIL-100 (Fe), MIL-100 (Al), MIL-101 (Cr) and aluminium fumarate MOF (FuAl)) were synthesized and the effect of gamma ray irradiation with a high dose rate and a maximum dose of 6 MGy was investigated. The two chromium-based MOFs, MIL-100 (Cr) and MIL-101 (Cr), were selected as radiation targets to produce high specific activity 51Cr by the Szilard-Chalmers effect. A solid–liquid extraction was applied to extract the produced 51Cr under different conditions, including different extractants, extraction times and pH. The most promising results were achieved when using irradiated MIL-101 (Cr) and EDTA as extracting agent, reaching an enrichment factor of 1132 ± 50.

High-Efficient photocatalytic degradation of Levofloxacin via a novel ternary Fe2O3/CeO2/ZnO Heterostructure: Synthesis Optimization, Characterization, toxicity assessment and mechanism insight

Considering the serious problem of lack of freshwater worldwide and the effectiveness of the photocatalysis process in water purification, we prepared a novel Ternary Fe2O3/CeO2/ZnO photocatalyst toward degradation of Levofloxacin (LEF) antibiotic. In this study, the CeO2 was synthesized through the hydrothermal route and the nanocomposite was prepared using a simple-impregnation method. Then the synthesized materials with various weight percentages 5 %FeCe (10, 20, 30 and 40 %) on the ZnO were completely characterized in the aspects of structural, morphological and optical properties with the aid of XRD, XPS, BET, TEM, SEM, EIS, ESR, Band-gap, Photocurrent, Mott Schottky, etc. The XPS analysis depicts the successful construction of required bonds among FeCe/ZnO materials. The enhancement of LEF decomposition was investigated utilizing RSM-CCD method, considering factors such as the amount of catalyst used, irradiation time, pH levels, and the initial concentration of LEF. The trapping experiments of free radicals highlight the significant contributions of the •OH and •O2– radicals. A notable degradation rate of 98.9 % was achieved under optimal operational conditions, which included catalyst dosage of 0.69 g/L, irradiation period of 83.64 min, initial LEF concentration of 37.9 mg/L, and pH of 6.18. Furthermore, the findings of EIS, photocurrent, and Mott-Schottky analyses allowed for proposing a suitable charge transfer mechanism and demonstrated effective separation of photo-generated electron-hole pairs. Additionally, LC-MS analysis was utilized to elucidate the intermediate products generated during the photodegradation of LEF, leading to the proposal of plausible degradation pathways. The exceptional efficiency of the 30FeCe/ZnO photocatalyst highlights its promising potential for the efficient treatment of persistent organic pollutants on a large scale in wastewater treatment plants.

Researches on the continuous-wave infrared laser-assisted-load icebreaking

In this paper, a novel continuous-wave infrared laser-assisted load icebreaking method for large-sized ice blocks is put forward, which employs a laser multipoint irradiation approach. By strategically changing the mode of deployment points, interlocking cracks and melt holes are generated within the ice. This process effectively weakens the strength of ice, thus decreasing the difficulty of icebreaking. Based on the interaction mechanism between laser and ice, a mathematical model describing the evolution of the local temperature and stress of ice during continuous-wave infrared laser irradiation is established. The effects of deployment mode, laser irradiation time and laser power on the temperature and stress fields are analyzed based on numerical simulation. The impact of laser multipoint irradiation on the superposition of the stress between adjacent deployment points is revealed. On this basis, the experiments of continuous-wave infrared laser-assisted static-load icebreaking and impact-load icebreaking are carried out with natural freshwater ice as the research object. The influences of deployment mode, laser irradiation time and laser power on the external force required for subsequent icebreaking and the final icebreaking effect are analyzed. The characteristics of continuous-wave infrared laser-assisted static-load and impact-load icebreaking are comprehensively compared. Ultimately, the conclusion that impact load is more suitable for laser-assisted load icebreaking is drawn. The outcomes of this study potentially provide a new perspective on the breaking of large-sized ice blocks in an efficient way.

Degradation, transformation and cytotoxicity of triphenyl phosphate on surface of different transition metal salts in atmospheric environment

Triphenyl phosphate (TPhP) and transition metal elements have been ubiquitously detected in the atmosphere, which can participate in atmospheric chemical reactions and induce damage to human health. Currently the understanding of TPhP degradation, transformation and cytotoxicity on atmospheric particles surface are still limited. Therefore, this study used laboratory simulation methods to investigate the influence of irradiation time, transition metal salts, relative humidity (RH) to TPhP degradation, transformation and relative cytotoxicity. TPhP was coated on particle surfaces of four transition metal salts (MnSO4, CuSO4, FeSO4 and Fe2(SO4)3) in the experiment. Within 12 h irradiation, the significant TPhP photodegradation can be observed on all particles surface. Among these influence factors, the irradiation and RH were the crucial aspects to TPhP degradation, which primarily affect the OH concentration in the atmosphere. The transition metal elements only exhibited slightly catalytic effect to TPhP degradation. The mechanism study indicated that the major degradation products of TPhP are diphenyl hydrogen phosphate (DPhP) and OH-DPhP, which originated from the phenoxy bond cleavage and hydroxylation of TPhP induced by OH. As for the cytotoxicity to A549 cells, all the transition metal particles coated with TPhP can cause cellular injury, which was chiefly induced by the transition metal salt. The possible cytotoxicity mechanism of these particles to A549 cells can be attributed to the excessive reactive oxygen species (ROS) production. This study may provide a further understanding of TPhP degradation and related cytotoxicity with the coexistent transition metal salts in the atmosphere.

Preparation of nanosheet g-C3N4 coupled with Polycalix [4] resorcinarene: Survey characterization and photocatalytic activity for the degradation of 4-Nitrophenol

Here, we have synthesized Polycalix[4]resorcinarene (PC4RA) covalently coupled with carbon-modified porous graphitic carbon nitride (g-C3N4). The nanocomposites were characterized by (FTIR), (XRD), (SEM), Transmission (TEM), and DRS–UV–Vis spectroscopic methods. Photocatalytic activities of the PC4RA/g-C3N4 nanocomposites with different ratios of g-C3N4 were evaluated for degradation of 4-Nitrophenol under visible light irradiation under light irradiation of λ ≥ 320 nm. Three parameters were applied including the initial concentration of 4-nitrophenol, the amount of photocatalyst, and irradiation time. and the results of the photocatalytic performance suggest that the catalytic activity is strongly influenced by the presence of the g-C3N4 content. Especially the nanocomposite’s photocatalytic efficiency was the highest (98.32 % after 120 min) when the ratio of g-C3N4 was (1/2). However, an increase of the photocatalytic activities was related to the interfacial transfer of photogenerated electrons and holes, leading to the effective charge separation. The durability and stability of the nanocomposites have been examined and can endure the experimental conditions even after eight successive cycles. This approach opens up an avenue for the fabrication of graphitic carbon nitrite-based metal-free heterogeneous nanocomposites with high catalytic performance.

Development of a Convenient and Quantitative Method for Evaluating Photosensitizing Activity Using Thiazolyl Blue Formazan Dye.

Photosensitizers cause oxidative damages in various biological systems under light. In this study, the method for analyzing photosensitizing activity of various dietary and medicinal sources was developed using 1-(4,5-dimethylthiazol-2-yl)-3,5-diphenylformazan (thiazolyl blue formazan; MTT-F) as a probe. Significant and quantitative decolorization of MTT-F was observed in the presence of photosensitizers used in this study under light but not under dark conditions. The decolorization of MTT-F occurred irradiation time-, light intensity-, and photosensitizer concentration-dependently. The decolorized MTT-F was reversibly reduced by living cells; the LC-MS/MS results indicated the formation of oxidized products with -1 m/z of base peak from MTT-F, suggesting that MTT-F decolorized by photosensitizers was its corresponding tetrazolium. The present results indicate that MTT-F is a reliable probe for the quantitative analysis of photosensitizing activities, and the MTT-F-based method can be an useful tool for screening and evaluating photosensitizing properties of various compounds used in many industrial purposes.

Conversion of iron rusty waste into Fe dopant of TiO2 to increase its photocatalytic activity under visible light for photodegradation of rhodamine-B

This present research deals with a systematic study on doping TiO2 with Fe from iron rusty waste to improve the activity under visible light irradiation through gap narrowing in the TiO2 semiconductor structure. The doping was conducted by the sol-gel method by interacting titania tetra isopropoxide (TTIP) with Fe3+ ions dissolved from the iron rusty waste in aqua regia. The concentration of the Fe3+ was varied giving mole ratio to TiO2 as (1:0.04), (1:0.08), (1:0.12), (1:0.16), and (1:0.20). The activity of TiO2–Fe was examined for Rhodamine-B dye photodegradation through batch technique. The influences of the Fe fraction, irradiation time, photocatalyst weight, and solution pH were also evaluated to find the best condition for the dye degradation. The research results attribute that doping TiO2 with Fe3+ from the rusty waste has successfully shifted the band gap energy into the visible regime, which remarkably increases the TiO2 activity under visible light irradiation. The increase is controlled by the Fe fraction in the photocatalyst, and the best performance is shown by TiO2–Fe with a 1:0.12 mol ratio. From the dye photodegradation, it is found that the highest degradation effectiveness (99.20 %) of 5 mg/L Rhodamine B in 50 mL of the solution, can be obtained by using 50 mg of TiO2–Fe (1:0.12), pH 5, in 90 min. The photocatalyst can be reused twice in the photodegradation process without a significant decrease in photoactivity. It is implied that the rusty waste has potential as a Fe dopant source creating a better visible responsive photocatalyst.

Controllable defects in monolayer graphene induced by hydrogen and argon plasma

Graphene has attracted wide attentions since its successfully exfoliation. Honeycomb sp 2 carbon lattice and Dirac semi-metal band structure make graphene a promising material with excellent mechanical strength, thermal conductivity, and carrier mobility. However, the absence of intrinsic bandgap limits its application in semiconductor. Defects in graphene is supposed to modify its band structure and lead to an opened bandgap. Many methods have been demonstrated to introduce defects into graphene, such as chemical reaction, plasma, electron beam, and laser. However, the species of defects are mostly uncontrollable in most treatment processes. In this study, we report three kinds of defects can be controllably induced in graphene via hydrogen (H2) and argon (Ar) plasma. With different parameter and feeding gas, hydrogenated graphene, graphene nanomesh and graphene with vacancies can be well obtained. The defect density can be precisely controlled by tuning plasma power and irradiation time. Morphological, spectroscopic, and electrical characterizations are performed to systematically investigate the defect evolution. Graphene nanomesh and graphene with vacancies show obvious difference for roughness and coverage, whereas the morphology of hydrogenated graphene remains similar with that of as-prepared graphene. For hydrogenated graphene, an opened bandgap of ∼20 meV is detected. For graphene nanomesh and graphene with vacancies, the semiconductive on/off behaviors are observed. We believe this work can provide more details of plasma-induced defects and assist the application of graphene in semiconductor industry.

Upconverting Nanoparticles Coated with Light-Breakable Mesoporous Silica for NIR-Triggered Release of Hydrophobic Molecules.

Upconverting nanoparticles (UCNPs) doped with Yb3+ and Tm3+ are near-infrared (NIR) to ultraviolet (UV) transducers that can be used for NIR-controlled drug delivery. However, due to the low quantum yield of upconversion, high laser powers and long irradiation times are required to trigger this drug release. In this work, we report the one-step synthesis of a nanocomposite consisting of a LiYbF4:Tm3+@LiYF4 UCNP coated with mesoporous UV-breakable organosilica shells of various thicknesses. We demonstrate that a thin shell accelerates the breakage of the shell at 1 W/cm2 NIR light exposure, a laser power up to 9 times lower than that of conventional systems. When the mesopores are loaded with hydrophobic vitamin D3 precursor 7-dehydrocholesterol (7-DH), shell breakage results in subsequent cargo release. Its minimal toxicity in HeLa cells and successful internalization into the cell cytoplasm demonstrate its biocompatibility and potential application in biological systems. The tunability of this system due to its simple, one-step synthesis process and its ability to operate at low laser powers opens up avenues in UCNP-powered NIR-triggered drug delivery toward a more scalable, flexible, and ultimately translational option.

Transformed construction from type-II WO3/BaTiO3 heterojunction to Z-scheme WO3/Ba0.5Sr0.5TiO3 and WO3/SrTiO3 photocatalytic systems: Enhanced photocatalytic activity and mechanism insight

In this study, type-II heterojunction WO3/BaTiO3 and Z-scheme WO3/SrTiO3 or WO3/Ba0.5Sr0.5TiO3 nanocomposite photocatalysts were constructed for photodegradation of organic pollutants in wastewater under visible light. The photocatalytic performance of three WO3/titanate systems were estimated. Some influencing factors such as molar ratio of WO3 and titanates, light irradiation time, catalyst dose, and initial concentration of organic pollutants on the photocatalytic activity were investigated. The stability and reusability of three WO3/titanates systems were examined. Moreover, the production of some radicals in the three WO3/titanates photocatalytic systems was demonstrated, and the three WO3/titanates photocatalytic reaction mechanisms were compared. The results reveal that the configurations of WO3/titanates photocatalytic systems are transformed from type-II heterojunction WO3/BaTiO3 with lower activity to Z-scheme WO3/SrTiO3 and WO3/Ba0.5Sr0.5TiO3 with higher activity via the change of titanates. The WO3/titanate nanocomposites show higher photocatalytic activity at 3.0:1.0 M ratio of WO3 and titanates, and WO3/Ba0.5Sr0.5TiO3 nanoparticles have superior photocatalytic activity. The order of photocatalytic activity is as follows: WO3/Ba0.5Sr0.5TiO3 > WO3/SrTiO3 > WO3/BaTiO3. Several organic pollutants, such as rhodamine B, methyl parathion, direct brilliant yellow-4R, and methylene blue, can be efficiently degraded using WO3/Ba0.5Sr0.5TiO3 under visible light, and the RhB has higher degradation rate. After four cycles, WO3/titanate nanocomposites still have relatively high stability and reusability. •OH plays a major role in three WO3/titanates photocatalytic degradation. It is expected that the Z-scheme WO3/Ba0.5Sr0.5TiO3 photocatalytic technology creates a good foreground for disposing of dyes and pesticides in water and wastewater.

Synthesize electrode material based on rGO/Polyacrylic acid prepared by a combination of direct ink writing technique and UV irradiation

In this work, the rGO/polyacrylic acid (rGO/PAA) composite film was synthesized using the 3D direct ink writing technique with GO/acrylic acid (GO/AA) ink and UV irradiation. Results show that after a UV irradiation time of 3.6 seconds, GO was reduced into rGO, and AA was polymerized into PAA. The prepared material was characterized by using Fourier Transform Infrared Spectroscopy (FT-IR), Energy-dispersive X-ray spectroscopy (EDX), cyclic voltammetry (CV), and galvanostatic charge/discharge technique (GCD). The obtained composite film is applied as an electrode for the supercapacitor. The electrode has a specific capacity of 321 F/g at a current density of 1 A/g and retains 82% of its initial capacity after 5,000 charge/discharge cycles at a current density of 5 A/g.

Synthesis and characterisation of MXene based-LDH photocatalytic materials for the removal of toxic pharmaceutical effluents

The synthesis of highly stable, cost-effective, and efficient photocatalyst materials is the major concern for wastewater remediation in the field of nanotechnology. Herein, the NiFe-LDH (NF-ldh) and its composites with gCN (NF-ldh/gCN) and MXene (NF-ldh/MXene) have been synthesized, characterized and their catalytic potential was explored in the presence of polluted water, discharged from pharmaceutical industries. The mineralization of contaminants has been analyzed by varying the concentration of photocatalysts and the irradiation time. The excellent photodegradation of brexin (BX) and omeprazole (MP) has been examined by the gCN and MXene-based nano-composites because of their porous structure and abundant active sites. Moreover, the carbonaceous materials (gCN and MXene) facilitate the charge transfer by reducing the recombination rate and enhances the absorption of light. The current research has demonstrated the alternative photocatalysts for the wastewater management by the contribution of the Xenon radiations.

Response Surface Methodology: An Optimal Design for Maximising the Efficiency of Microwave-Assisted Extraction of Total Phenolic Compounds from Coriandrum sativum Leaves

The optimization of total phenolic compounds (TPC) extraction yield and maximization of total antioxidant capacity (TAC) from coriander leaves were investigated using response surface methodology. The extraction of TPC was carried out using microwave-assisted extraction. A Box-Behnken design was used to study the effects of the three independent variables, solvent concentration (ethanol/water 20–80%), microwave power (100–500 watt) and irradiation time (30–150 s) on the response. A second-order polynomial model was used to predict the reaction. The regression analysis showed that about 99% of the variations could be explained by the models. The predicted values were 50.97 GAE/g dw and 5.75 mg GAE/g dw for TPC and TAC. The reaction surface analysis showed that the optimum extraction parameters that maximized the extraction of antioxidants yield were 52.62% ethanol, 452.12 watt and 150 s. Under optimal conditions, the experimental values for TPC and TAC were 49.63 ± 0.93 mg GAE/g dw and 5.55 ± 0.07 mg GAE/g dw, respectively. The experimental values are in agreement with the predicted values, indicating the suitability of the model used and the success of the response surface methodology in optimizing the extraction conditions.