Smaller Particle Size Distribution Research Articles

Study of Electron Beam Irradiated Palladium on Carbon Catalysts for Transfer Hydrogenation Reactions of Nitroarenes Compounds

Palladium-catalyzed hydrogenation is considered a crucial stage in the entire synthesis of difficult natural products as well as a crucial step in the manufacturing of fine compounds used in pharmaceuticals. When it comes to the reaction rate and simplicity of work-up, using Pd/C as heterogeneous catalyst is one of the best choice for process efficiency. In this study, nitroarenes compounds viz. 3-bromo nitrobenzene, 4-fluoro nitrobenzene, 3-methyl nitrobenzene, 4-hydroxy nitrobenzene reduced by using macro 10% Pd/C and micro 10% Pd/C to 3-bromo aniline, 4-fluoro aniline, 3-methyl aniline, 4-hydroxy aniline respectively and verified from 1H NMR studies. The reduction reactions were similar conditions using electron beam irradiated 250 kGy macro and micro 10% Pd/C catalyst. The effectiveness of commercial sources of palladium on carbon (Pd/C) varies widely, leading to the appreciable variations in the reaction times. The decrease in reaction time has been attributed to the higher dispersion of Pd particles upon irradiation. The physico-chemical characteristics of effective hydrogenation catalysts were determined to be: (i) small Pd particle size and (ii) homogeneous distribution of Pd on the carbon support. With no significant loss of catalytic activity, the electron beam-irradiated catalyst can be used again for five runs. These days, chemists can determine as well as forecast the effectiveness of catalysts before investing time and money in expensive synthetic materials.

Physical and Chemical Properties of Volcanic Ejecta Produced During the Eruption of Shinmoe-Dake, Mt. Kirishima: Explosive Eruption on March 25, 2018

The objective of this study was to clarify the actual physical and chemical properties of volcanic ejecta immediately after the explosive eruption of Shinmoe-dake, Mt. Kirishima, in Japan. The day after the explosive eruption occurred on March 25, 2018, permeability tests using a cylindrical frame were conducted, and samples collected in the test site were subjected to laboratory soil tests. The real infiltration capacity of the volcanic ejecta showed that the final values were lower (38–92 mm/h) in the talus inside the forest than in the plain outside the forest. This was attributed to the small particle size distribution above 1 mm, regardless of the particle size of the silt/clay particle size segment. The rainfall after the explosive eruption was at most 20–22 mm/h, indicating that the real infiltration capacity value at the end of the eruption was higher than the rainfall value. This was consistent with the fact that no debris-flow was observed at the foot of Shinmoe-dake after the recent eruption. On the other hand, examination of the chemical properties of the volcanic ejecta collected revealed high values of Ca and SO4. These compounds form gypsums by reaction with water, could reduce the infiltration capacity of deposit, possibly contributing generation of mudslide.

Utilizing phytochemical-rich spent coffee ground extract for eco-friendly ZnO electrochemical synthesis: Assessing photocatalytic efficacy in 2,4-dichlorophenol degradation

The study explores an alternative electrolyte derived from spent coffee ground (SCG) extract for electrochemical synthesis of zinc oxide (ZnO), aiming to address limitations associated with toxic electrolytes. Three extraction methods specifically, facile, microwave-assisted, and ultrasonic-assisted, were employed to prepare SCG extracts, resulting in ZnO-F, ZnO-MW, and ZnO-UAE, respectively. An organic solvent-mediated catalyst, ZnO-DMF, was synthesized using N, N-dimethylformamide, and served as a comparison. All catalysts were characterized via FTIR, SEM, XRD, BET, PSA, XPS and UV-DRS. The photocatalytic activity was evaluated under visible light through 2,4-dichlorophenol (2,4-DCP) degradation. The facile extraction method yielded the most phytochemical-rich SCG extract, leading to the highest catalytic activity of ZnO-F (92.6 %), followed by ZnO-MW (89.2 %) and ZnO-UAE (83.4 %). Notably, ZnO-DMF exhibited similar degradation efficiency (92 %) to ZnO-F. The ZnO-F’s smaller particle size distribution (Dv [90] = 186 µm) and smaller band gap energy (Eg, 3.18 eV) accredited to phytochemicals involvement during electrosynthesis, compensated its poor crystallinity (relative to ZnO-DMF) hence resulting in equivalent photocatalytic capacity with the organic solvent-mediated ZnO. Further optimization using ZnO-F identified pH 3, 30 ppm of 2,4-DCP, and 0.01 g of catalyst loading as the optimal conditions. The reusability test revealed that ZnO-F can be reused for a maximum of 3 cycles with 80 % degradation at the final cycle. Kinetic and scavenger studies revealed a pseudo-first-order degradation mechanism and photogenerated holes as the main species influencing 2,4-DCP degradation, respectively. This investigation accentuates the potential of SCG extract as a green electrolyte for eco-friendly ZnO synthesis with promising photocatalytic applications.

Long carbon chain-modified carbon nanoparticles for oil displacement in harsh-condition reservoirs

Carbon nanoparticles, as an emerging type of enhanced oil recovery agent, promising broad prospects in unconventional oil and gas development. However, limitations such as low interfacial activity due to the strong hydrophilicity of carbon nanoparticles and tendency to aggregate under high-temperature and high-salinity conditions restrict their further application. In this study, activity carbon dots (S-CDs) were prepared via a simple two-step hydrothermal reaction. A range of physicochemical techniques characterized S-CDs, revealing their small particle size (1.4 ± 0.01 nm) and narrow distribution, maintaining strong dispersion stability in mineralized water at 130 °C with a concentration of 16 × 104 mg/L. The AFM scanning results indicated that S-CDs possessed strong interfacial wetting control capability, the adhesion force between oil and rock cores (after S-CDs treatment) decreased by 25 times. Particle Image Velocimetry (PIV) confirmed that S-CD adsorbed at the oil-water interface could formed a solid film, which could rupture into smaller oil droplets for convenient backward migration. The results demonstrated that S-CDs improved the interfacial activity while maintaining the hydrophilicity of CDs. In core displacement experiments, 0.05 wt% S-CDs nanofluid reduced injection pressure by 32.4 % and increased recovery rates by 34.9 %. This work provides new insights for the development of high-temperature, high-salinity displacement agents in harsh-condition reservoirs.

Effect of pre-treatment on physicochemical, microstructural and pasting properties of pearl millet and cowpea

The effects of soaking, germination and fermentation on physicochemical, microstructural and pasting properties of improved and drought-tolerant Mozambican varieties of pearl millet and cowpea were investigated.Total starch content in both germinated pearl millet (GPM, 67.2 % of DM) and germinated cowpea (GCP, 47.4 % of DM) was found to be affected by germination, which consequently affected the amylose content of GPM and GCP. Morphological and pasting properties of pearl millet starch granules were altered by germination, with numerous holes and broken starch granules developing, leading to a drastic reduction in final viscosity (4 mPa.s). Cowpea starch granule structure was not markedly affected by pre-treatment, but peak (310 mPa.s) and final viscosity (196 mPa.s) were decreased by germination. Cowpea flour had smaller particle size distribution than pearl millet, but no significant differences in the flour were observed after pre-treatment (soaking, germination, fermentation). Therefore, these simple, low-cost and culturally acceptable treatments can be used to alter technical functionality and improve the nutritional benefits of flour, e.g. different pre-treatments of pearl millet and cowpea could be used to develop food products with high energy density and acceptable sensory profile such as porridge for undernourished children in low and middle-income countries.

Ecofriendly cascade extraction of antioxidants from Origanum vulgare: Morphological and rheological behavior of microparticles formulations

Bioactive compounds from Origanum vulgare have been extracted to enriched foods. This has contributed to consumer acceptance. These extracts have been obtained using a sequential extraction process to recover the maximum amount of the bioactive compounds for the formulation of microparticles. Extracts obtained from both extraction technologies (ultrasound and pressurized hot water extraction) were analyzed. When the ultrasound technology was used, total phenolic content and protein content were highest (29 % and 4.7 %, respectively). The second extraction showed lower values around 72 % for TEAC value, 14 % phenolic content and 5.4 % protein content (g/100 extract). The IC50 for the ultrasound extract is 0.27 g/L and the lower value for the sequential treatment is 0.49 g/L. The polymeric microparticles were formulated with the ultrasound extract at different percentages of mannitol (2 % and 5 %). It was observed that microparticles (5 % mannitol) had a smaller particle size distribution (∼12 µm) and flow curves exhibiting shear-thinning behavior, which were successfully fitted with the power law model.

Enhanced mechanical properties of epoxy composites using cellulose micro‐ and nano‐crystals

AbstractEpoxy polymers are commonly utilized in structural applications due to their high bearing capacity and excellent chemical resistance. However, their inherent brittleness poses a significant challenge for their use in high shock and fracture strength products. To address this shortcoming, fillers can be incorporated into the polymer during preparation. In this study, we aimed to investigate the effect of incorporating cellulose‐based fillers, namely cellulose nanocrystals (CNCs) and microcrystalline cellulose (MCC), on the mechanical properties of epoxy polymer composites. The study evaluated the impact of various factors, including filler concentration, particle size, and moisture content, on the mechanical properties of the composites. The results demonstrated that the incorporation of CNC or MCC powders at concentrations below 5% could enhance the mechanical properties of the resulting epoxy composites without adversely affecting their surface and thermal properties. The maximum tensile strength and fracture toughness of the filler‐based epoxy composites were achieved at 2 and 4 wt% for CNCs and MCC, respectively. CNCs with a smaller particle size distribution were found to be much more effective than MCC in improving the mechanical properties of the epoxy composites. Furthermore, utilizing dried fillers resulted in a higher improvement in tensile strength, which was achieved at lower filler concentrations.

Towards enhancing ODS composites in laser powder bed fusion: Investigating the incorporation of laser-generated zirconia nanoparticles in a model iron–chromium alloy

Oxide dispersion-strengthened (ODS) steel is a sought-after composite material known for its high demand in high-temperature and corrosive environments. Achieving the desired ODS steel properties requires specific conditions for the size and nanoparticles (NP) distribution in the printed part. Laser ablation in liquid (LAL) enables precise NP size adjustment. At the same time, the dynamic melt pool solidification in the Laser Powder Bed Fusion (PBF-LB/M) process complements this by creating favorable conditions for successful ODS processing. In this study, ZrO2 NP with a small and narrow particle size distribution (d50 = 3.8 nm; d90 = 10 nm) is produced by LAL. Dielectrophoretic deposition achieves the homogeneous, deformation-free coating of the binary Fe20Cr (wt.-%) matrix powder with NP. PBF-LB/M printed parts out of the oxide-additivated powder exhibit a crack-free structure and a density of up to 98%. Expectedly, the metal matrix grain sizes and room temperature microhardness (~ 220 HV) are not affected by NP addition. NP tracing by 2D simulation indicates a homogeneous NP distribution and less than 10% NP to be agglomerated in the solidified part. Thus, a promising perspective for a complete laser-based process chain for generating and processing ODS alloys is outlined.Graphical abstractTable of Contents

A novel plant-based milk alternative made from red kidney bean (Phaseolus vulgaris L.): Effects of cultivars on its stability and sensory properties

The growing popularity of plant-based milk alternatives has driven the creation of many novel products to meet the consumers’ diverse requirements. Red kidney bean (Phaseolus vulgaris L.) is an underutilized legume that might be used to develop a novel plant-based milk alternative due to its high protein content and diverse health benefits. It has demonstrated that the stability and sensory properties of plant-based milk were significantly affected by the cultivars of the raw material. The objectives of this study were unique to compare the physicochemical stability and sensory characteristics of plant-based milk from four different red kidney bean varieties grown in China. Furthermore, the possible differential mechanisms were explored by analyzing the rheological properties, protein solubility, surface hydrophobicity, surface tension, and microstructure of red kidney bean milk. The results showed that compared with the other three red kidney bean varieties, Jizhangyun-2 (JZY-2) exhibited excellent physicochemical stability with a lower centrifugal sedimentation rate (8.04%), smaller particle size distribution (2.54 μm), and higher potential (−23.03 mV). Furthermore, the enhanced protein solubility and surface hydrophobicity, as well as the decreased surface tension and aggregation degree of protein in JZY-2 kidney bean milk were deemed to be responsible for the results. The color and sensory analysis also supported that the JZY-2 kidney bean was suitable to prepare a novel plant-based milk alternative.

Controlled synthesis of ZIFs by microemulsion method at high-throughput in a chaotic microreactor

The average size and particle size distribution (PSD) of zeolitic imidazolate frameworks (ZIFs) (such as ZIF-8, ZIF-67) are closely related to their physical and chemical properties. However, it is difficult to prepare small ZIFs with narrow PSD in traditional batch reactors owing to poor mixing efficiency. Here, a four-stage oscillating feedback microreactor (FOFM) was developed to prepare ZIFs by microemulsion method. CFD simulations and visualization experiments were conducted to investigate liquid-liquid two-phase flow patterns involved, demonstrating that chaotic advection can be effectively produced, thus dispersed phase is broken up into small droplets and homogeneous microemulsions are obtained. The proposed microemulsion method based on FOFM enables preparation of ZIF-8 with small average size (38.2 nm) and narrow PSD (σg = 1.24) without surfactant at a flow rate of 90 mL/min.

Effect of ionic types on the characteristics of Pickering emulsions stabilized by myofibrillar proteins from hairtail (Trichiurus lepturus)

Ion is an important factor to affect the characteristics of protein-based Pickering emulsions. However, the effect of ionic types on the characteristics of Pickering emulsions prepared by myofibrillar proteins (MPs) from hairtail (Trichiurus lepturus) is still unclear. Therefore, the characteristics of Pickering emulsions stabilized by MPs (MPPEs) at different metal ions (Na+, K+, Mg2+, Ca2+) were investigated. MPPEs at Na+ and K+ possessed high absolute values of Zeta potential, small particle size and uniform distribution of emulsion droplets compared to that at Mg2+ and Ca2+. After heat treatment, the particle size of MPPEs at Na+ and K+ had no significant change with high stability compared to that at Mg2+ and Ca2+. MPPEs at Na+ and K+ exhibited gel-like behavior and relatively stable compared with those at bivalent ions (Mg2+ and Ca2+). This study may be helpful for the high-value utilization of fish proteins in constructing emulsion systems.

Encapsulation of essential oil to prepare environment friendly nanobio-fungicide against Fusarium oxysporum f.sp. lycopersici: An experimental and molecular dynamics approach

This study aims to develop a nano-biofungicide comprising of volatile essential oil molecules to enhance its efficacy in the field of agriculture through easily scalable green synthesis technique. It was prepared through one pot hot melt ultrasonication technique with easy water dispersability and long term stability. The effective surface-active agent concentration which controls the size and stability of nano bio-fungicide was studied. The small particle size (158 nm) and narrow particle distribution (0.36) were obtained for the nano bio-fungicide at 20 mg of lecithin and 100 mg of surfactant concentration. The physico-chemical analysis revealed that, nano bio-fungicides were amorphous sphere-shaped nanoparticles with low melting point. The greater molecular level affinity of essential oil towards lipids and their interfacial interaction towards essential oil to achieve stabilised dispersion in aqueous environment were deciphered through molecular dynamics simulation. The unique preferential binding of eugenol, bornanone and cinnamaldehyde with the hydrocarbon chain of glycerol monostearate and phospholipid enhanced their biological stability in aqueous environment by preventing its autoxidation. It was further confirmed through accelarated ageing studies. The major components of essential oil like alpha-terpineol, linalool, thymol and cinamaldehyde had an encapsulation efficiency of 29 %, 65 %, 21 % and 50 % respectively. Subsequently, all these bioactives of essential oil follows Higuchi model of release kinetics. Besides, the essential oil loaded nanostructured lipid carrier had significantly higher mycelial growth inhibition than pure essential oil at the same concentration. Thus, our results suggest that essential oil compactly packed at the intramolecular spaces of lipids and surfactants were having enhanced bio-efficacy with long term storage potential. Hence, the present nano-biofungicide could be a good alternative to the harsh pesticidal chemicals with easy and simple large scale production protocol for the eco- friendly management of wilt disease caused by Fuarium oxysporum.

Microfluidic-based nanoemulsion of Ocimum basilicum extract: Constituents, stability, characterization, and potential biomedical applications for improved antimicrobial and anticancer properties.

This paper reports on the findings from a study that aimed to identify and characterize the constituents of Ocimum basilicum extract using gas chromatography-mass spectrometry (GC-MS) analysis, as well as assess the physicochemical properties and stability of nanoemulsions formulated with O. basilicum extract. The GC-MS analysis revealed that the O. basilicum extract contained 22 components, with Caryophyllene and Naringenin identified as the primary active constituents. The nanoemulsion formulation demonstrated excellent potential for use in the biomedical field, with a small and uniform particle size distribution, a negative zeta potential, and high encapsulation efficiency for the O. basilicum extract. The nanoemulsions exhibited spherical morphology and remained physically stable for up to 6 months. In vitro release studies indicated sustained release of the extract from the nanoemulsion formulation compared to the free extract solution. Furthermore, the developed nanoformulation exhibited enhanced anticancer properties against K562 cells while demonstrating low toxicity in normal cells (HEK293). The O. basilicum extract demonstrated antimicrobial activity against Pseudomonas aeruginosa, Candida albicans, and Staphylococcus epidermidis, with a potential synergistic effect observed when combined with the nanoemulsion. These findings contribute to the understanding of the constituents and potential applications of O. basilicum extract and its nanoemulsion formulation in various fields, including healthcare and pharmaceutical industries. Further optimization and research are necessary to maximize the efficacy and antimicrobial activity of the extract and its nanoformulation. RESEARCH HIGHLIGHTS: This study characterized the constituents of O. basilicum extract and assessed the physicochemical properties and stability of its nanoemulsion formulation. The O. basilicum extract contained 22 components, with Caryophyllene and Naringenin identified as the primary active constituents. The nanoemulsion formulation demonstrated excellent potential for biomedical applications, with sustained release of the extract, low toxicity, and enhanced anticancer and antimicrobial properties. The findings contribute to the understanding of the potential applications of O. basilicum extract and its nanoemulsion formulation in healthcare and pharmaceutical industries, highlighting the need for further optimization and research.

Facile preparation of PEGylated polyethylenimine polymers as vaccine carriers with reduced cytotoxicity and enhanced Interleukin-2 (IL-2) production.

Developing low-cost, easy-to-prepare, biocompatible and highly efficient vaccine carriers is a promising approach to realize practical cancer immunotherapy. In this study, through facile modification of mPEG5k-4-toluenesulfonate (mPEG5k-OTs) on PEI25k under mild conditions, a series of "stealth" mPEG5k-PEI25k polymers (PP1, PP2 and PP3) were prepared, their structures and physicochemical properties were characterized and theoretically analyzed. The polymers could bind/load ovalbumin (OVA) to form mPEG5k-PEI25k/OVA complexes as negatively charged nanoparticles with small hydrodynamic particle size (80-210nm) and narrow size distribution. Compared to PEI25k/OVA, lower cytotoxicity could be achieved on mPEG5k-PEI25k/OVA complexes in dendritic cells (DCs). In DCs-RF 33.70T-cells co-culture system, the mPEG5k-PEI25k/OVA complexes could bring about higher IL-2 production /secretion than that of PEI25k/OVA, notably, the optimum IL-2 secretion could reach 9.3-folds of the PEI25k/OVA under serum condition (10% FBS). Moreover, the cell biological features could be optimized by selecting suitable mPEG5k-grafting ratios and/or mPEG5k-PEI25k/OVA weight ratios. Intracellular imaging results showed that the mPEG5k-PEI25k(PP3)/Rhodamine-OVA complexes mainly localized inside lysosomes. Taken together, this work provided a facile method to prepare "stealth" PEGylated-PEI25k polymers with reduced cytotoxicity, promoted OVA cross-presentation efficiency and improved serum compatibility towards cancer immunotherapy.

Activated carbon obtained from coffee husk waste activated by CaCl2 as support of TiO2 for the enhanced photocatalytic degradation of Victoria Blue B dye

In this study, we demonstrated the viability of the production of activated carbon (AC) from coffee husk waste and their activation using CaCl2. In addition, the prepared AC was used as support for TiO2, and the TiO2/AC composite was employed as a photocatalyst in the Victoria Blue B (VBB) photodegradation. Specifically, the coffee husk was carbonized at 800 °C for 1 h and then activated with CaCl2 at 850 °C, varying the heating time by 0.5, 1, 2, and 4 h. The activated carbons (ACs) treated within 1 and 2 h presented the highest surface area and were used to support TiO2 prepared by the sol-gel method. The surface area did not decrease after dispersion, keeping about 700 m2.g−1, which suggested the uniform distribution of TiO2 onto the surface of the ACs, confirmed by SEM and TEM analysis. In addition, TEM analyses revealed a small particle size distribution of TiO2 nanoparticles (3.4 nm for TiO2/AC_1_350 and 4.8 nm for TiO2/AC_2_350), indicating that they do not have enough dimensions to block the AC pores structure. X-ray diffraction, TGA, and XPS analyses revealed the combination of TiO2 nanoparticles with AC, generating a hybrid material. The photocatalytic activity of the TiO2/AC composite is very fast, removing about 99 % of the VBB dye after 120 min of photocatalytic degradation. The recyclability of the TiO2/AC catalyst was also evaluated in three consecutive reactions, showing that the nanocomposite could be used for multiple degradations without a decrease in photocatalytic activity. Thus, this study proved the feasibility of using coffee husk wastes for AC preparation and its use as a photocatalyst in conjunction with TiO2.

Design, development and in vitro quantification of novel electrosprayed everolimus-loaded Soluplus®/Polyvinyl alcohol nanoparticles via stability-indicating HPLC method in cancer therapy

Everolimus (RAD001) a mammalian target of rapamycin has been hampered by poor solubility, affecting its dissolution rate, a relationship that extends to low bioavailability. Nanoparticles (NP) based on Soluplus (SOL®) and Polyvinyl alcohol (PVA) was fabricated by electrospraying (ES) for the delivery of RAD001 to improve anti-tumour efficacy. Electrospraying with established experimental conditions produced PVA-SOL®-RAD001 NP with 71 nm mean diameter, smaller particle size distribution and >90 % encapsulation efficiency. Various polymer-drug concentrations exposed to various freeze–thaw (F/T) cycles were studied for NP optimisation and to enhance its mechanical properties. The optimised NP formulation demonstrated complete encapsulation as well as a sustained and pH dependent drug release profile for in vitro release test. In addition, to specifically study the degradation profile of RAD001 and to quantify RAD001 in the fabricated NP, a new HPLC method was developed and validated. The purpose and novelty of the HPLC method was also to ensure that RAD001 can be detected at low amounts where other conventional characterisation methods are unable to detect. The developed HPLC method was accurate, precise, robust and sensitive with LOD and LOQ values of 4.149 and 12.575 μg/mL. In conclusion, the novel developed HPLC system can be applied for the quantification of different chemotherapeutic agents and the novel electrosprayed hydrogel NP is a potential drug delivery system to increase solubility and bioavailability of RAD001 in cancer therapy.

Synthesis and characterization of Ce0.5Bi0.5VO4/rGO nanocomposite by sonochemical method for photocatalytic desulfurization of petroleum derivatives

In order to improve the desulfurization efficiency of petroleum derivatives, Ce0.5Bi0.5VO4/rGO nanocomposite was synthesized by sonochemical method. The prepared nanocomposites were characterized by XRD, FESEM, EDS, FT-IR, BET, and DRS analyses. XRD analysis shows that the synthesized nanocomposite is amorphous. FESEM images showed that nanostructures with a smaller particle size distribution were synthesized under optimal conditions, i.e. controlling the synthesis temperature between 0 and 5 °C. The results of desulfurization showed that nanocomposites containing reduced graphene oxide (rGO) have higher photocatalytic efficiency than pure samples, the main reason of which can be better charge separation in the samples through the π electron in the rGO structure. The highest amount of desulfurization of CeVO4/rGO, BiVO4/rGO, and Ce0.5Bi0.5VO4/rGO nanocomposites was 95.62, 91.25, and 96.38%, respectively, after exposure to UV light for 40 min. The enhancement of photocatalytic activity of Ce0.5Bi0.5VO4/rGO composite could be attributed to the efficient separation of electron–hole pairs and the inhibition of recombination. Desulfurization in the presence of hydrochloric acid and hydrogen peroxide increased the efficiency by 12%, which is a significant amount.

Rapid microwave synthesis of N and S dual-doped carbon quantum dots for natamycin determination based on fluorescence switch-off assay

Green, one-pot, quick, and easily synthesized nitrogen and sulfur co-doped carbon quantum dots (N,S-CDs) were obtained from cheap and readily available chemicals (sucrose, urea, and thiourea) using a microwave-assisted approach in about 4 min and utilized as a turn-off fluorescent sensor for estimation of natamycin (NAT). First, the effect of N and S doping on the microwave-synthesized CDs’ quantum yield was carefully studied. CDs derived from sucrose alone failed to produce a high quantum yield; then, to increase the quantum yield, doping with heteroatoms was carried out using either urea or thiourea. A slight increase in quantum yield was observed upon using thiourea with sucrose, while an obvious enhancement of quantum yield was obtained when urea was used instead of thiourea. Surprisingly, using a combination of urea and thiourea together results in N,S-CDs with the highest quantum yield (53.5%), uniform and small particle size distribution, and extended stability. The fluorescent signal of N,S-CDs was quenched upon addition of NAT due to inner filter effect and static quenching in a manner that allowed for quantitative determination of NAT over a range of 0.5–10.0 μg ml−1 (LOD = 0.10 μg ml−1). The N,S-CDs were applicable for determination of NAT in aqueous humor, eye drops, different environmental water samples, and bread with excellent performance. The selectivity study indicated excellent selectivity of the prepared N,S-CDs toward NAT with little interference from possibly interfering substances. In-silico toxicological evaluation of NAT was conducted to estimate its long-term toxicity and drug-drug interactions. Finally, the preparation of N,S-CDs, and analytical procedure compliance with the green chemistry principles were confirmed by two greenness assessment tools.

Effects of a sidestream concentrated oxygen supply system on the membrane filtration performance of a high-loaded membrane bioreactor

To investigate the influence of high-pressure and shear effects introduced by a concentrated oxygen supply system on the membrane filtration performance, a laboratory-scale membrane bioreactor (MBR) fed artificial municipal wastewater was operated continuously for 80 days in four phases equipped with different aerations systems: (P1) bubble diffusers (days 0–40), (P2) concentrated oxygen supply system, the supersaturated dissolved oxygen (SDOX) (days 41–56), (P3) bubble diffusers (days 57–74), and (P4) SDOX (days 75–80). Various sludge physical-chemical parameters, visual inspection of the membrane, and permeability evaluations were performed. Results showed that the high-pressure effects contributed to fouling of the membranes compared to the bubble diffuser aeration system. Biofouling by microorganisms appeared to be the main contributor to the cake layer when bubble diffusers were used, while fouling by organic matter seemed to be the main contributor to the cake layer when SDOX was used. Small particle size distribution (PSD) (ranging from 1 to 10 and 1–50 μm in size) fractions are a main parameter affecting the intense fouling of membranes (e.g., formation of a dense and thin cake layer). However, PSD alone cannot explain the worsened membrane fouling tendency. Therefore, it can be assumed that a combination of several factors (which certainly includes PSD) led to the severe membrane fouling caused by the high-pressure and shear.

Effect of High-Energy Ball Milling in Ternary Material System of (Mg-Sn-Na)

In this study, the nature of the ball-milling mechanism in a ternary materials system (Mg-6Sn-1Na) is investigated for proper mechanical alloying. An identical powder mixture for this material system is exposed to different milling durations for a suitable mixture. First, the platelet structure formation is observed on particles with increasing milling duration, mainly formed in <200> direction of the hexagonal crystal structure of the Mg matrix. Then, the flake structure with texture formation is broken into smaller spherical particles with further ball milling up to 12 h. According to EDS analysis, the secondary phases in the Mg matrix are homogenously distributed with a 12-h milling duration which advises a proper mixture in this material system. The solid solution formation is triggered with an 8-h milling duration according to XRD analysis on 101 reflections. Conventional sintering is performed at 350 °C in 2 h for each sample. In bulk samples, XRD data reveal that secondary phases (Mg2Sn) with island-like structures are formed on the Mg matrix for a milling duration of up to 8 h. These bigger secondary phases are mainly constituted as Mg2Sn intermetallic forms, which have a negative effect on physical and mechanical properties due to a mismatch in the grain boundary formation. However, the homogenous distribution of secondary phases with a smaller particle size distribution, acquired with 12 h milling time, provides the highest density, modulus of elasticity, and hardness values for this ternary materials system. The ternary materials produced with the 12-h ball-milling process provide an improvement of about 117% in hardness value compared with the cast form.