Chemical Reduction Research Articles

Bimetallic NiCo Nanoparticles Embedded in Organic Group Functionalized Mesoporous Silica for Efficient Hydrogen Production from Ammonia Borane Hydrolysis

In this study, bimetallic NiCo nanoparticles (NPs) were encapsulated within the mesopores of carboxylic acid functionalized mesoporous silica (CMS) through the chemical reduction approach. Both NaBH4 and NH3BH3 were used as reducing agents to reduce the metal ions simultaneously. The resulting composite was used as a catalyst for hydrolysis of ammonia borane (NH3BH3, AB) to produce H2. The bimetallic NiCo NPs supported on carboxylic group functionalized mesoporous silica, referred to as NixCo100−x@CMS, exhibited significantly higher catalytic activity for AB hydrolysis compared to their monometallic counterparts. The remarkable activity of NixCo100−x@CMS could be ascribed to the synergistic contributions of Ni and Co, redox reaction during the hydrolysis, and the fine-tuned electronic structure. The catalytic performance of the NixCo100−x@CMS nanocatalyst was observed to be dependent on the composition of Ni and Co. Among all the compositions investigated, Ni40Co60@CMS demonstrated the highest catalytic activity, with a turn over frequency (TOF) of 18.95 molH2min−1molcatalyst−1 and H2 production rate of 8.0 L min−1g−1. The activity of Ni40Co60@CMS was approximately three times greater than that of Ni@CMS and about two times that of Co@CMS. The superior activity of Ni40Co60@CMS was attributed to its finely-tuned electronic structure, resulting from the electron transfer of Ni to Co. Furthermore, the nanocatalyst exhibited excellent durability, as the carboxylate group in the support provided a strong metal–support interaction, securely anchoring the NPs within the mesopores, preventing both agglomeration and leakage.

Facile Access to Phosphorus Ylide-fused Heteroarenes Possessing Tunable Optoelectronic Properties and High Nonlinear Optical Performances.

We report here a novel family of ylidic P-heteroarenes (P1-P6), structurally featuring unique phosphonium cyclopentadienylide (P-Cp)-fused π-skeletons and synthetically prepared via an unexpected one-pot [2+3]/[3+3] phospha-annulation reaction. While the facile and modular synthesis allows the fine-tuning of their optical absorptions and redox properties, single-crystallographic and theoretical analysis of these P-heteroarenes further reveal that the fusion of P-Cp moiety leads to substantial intramolecular charge-separated features with high ylidic character values of up to 84 %. Benefitted from such dipolar structures, these P-heteroarenes not only allows stepwise electrophilic substitution reaction for further structural π-expansions, but also exhibit excellent nonlinear optical (NLO) responses and optical limiting (OL) performances comparable to or exceed those of C60. As a model compound, the persistent radical-anion salt of P5a was also prepared through chemical reduction, thus offering valuable insights into the electronic structures of reduced P-ylidic species. Our work not only established a highly efficient synthetic method toward new P-heteroarenes, but also provide fundamental understanding of those fused-ring ylidic P-heterocycles with promising NLO/OL applications.

Synthesis of Nanoparticle ZnO via Chemical Reduction Using Singkil (<i>Premna serratifolia linn</i>) Leaf Extract as Photocatalytic

Nanoparticles are one of the widely studied research topics. ZnO nanoparticles have numerous benefits, such as photocatalysts and antibacterial applications. Methylene blue, which a highly dangerous and pollutes the environment and human health, is mostly used as a coloring dye in the textile industry. The use of biodegradation to treat textile waste is time-consuming and less effective. Applying photocatalysts using semiconductor materials is a more efficient method than conventional approaches for decomposing organic waste. One environmentally friendly method is green synthesis, which involves the use of microorganisms, enzymes, and plant extracts in the fabrication process. In this study, the green synthesis using chemical reduction of Premna serratifolia linn leaf extract was used to produce ZnO nanoparticles. The objective of this study is to investigate the effect of temperature on the fabrication of ZnO nanoparticles and their photocatalytic performance. Zinc nitrate tetrahydrate was used as a precursor, and the furnace temperature was varied at 400, 500, and 600 °C. The obtained ZnO was then tested using scanning electron microscopy (SEM), X-ray diffractometry (XRD), and Fourier transforms infrared spectrophotometry (FTIR). Moreover, the photocatalytic test was evaluated by examining the degradation efficiency of methylene blue using UV light. The XRD analysis indicated that the ZnO nanoparticles had crystallite sizes ranging between 44-60 nm. The SEM morphological test showed that the ZnO particles had a nano-sized spherical shape. The FTIR test results demonstrated the presence of ZnO peaks around 520 cm‑1. The performance of photocatalytic activity under UV light irradiation was significantly affected by tuning the temperatures. It was observed that the photocatalytic activity increased with increasing temperature, and methylene blue degradation efficiency reached 50% at a temperature of 600 °C. The ability of ZnO as a photocatalyst material was also evaluated by recycling the used material two times, where there was no significant change in photocatalytic performance.

Independent LUMO Reactivity in Mesoionic N‐Heterocyclic Thiones: Synthesis of a Stable Radical Anion

AbstractMesoionic compounds, with positive and negative charges, are expected to have dual‐site highest occupied molecular orbital (HOMO, donor) and lowest unoccupied molecular orbital (LUMO, acceptor) reactivity. Herein, we report a novel class of air‐stable mesoionic N‐heterocyclic thiones (mNHTs) synthesized from abnormal N‐heterocyclic carbenes (aNHCs). DFT studies revealed a highly polarized exocyclic thione moiety and computed Fukui function analysis suggests the dual‐site HOMO/LUMO reactivity of mNHTs predicting donor property at the negatively charged ‘S’ center while acceptor property at the cationic imidazole ring. The independent LUMO reactivity of the mNHT was realized by its chemical reduction to an elusive radical anion, which was characterized by a single crystal X‐raydiffraction study. Further, we explore the reactivity of radical anion for the activation of SO2 gas, C−Br bonds of aryl bromide and photocatalytic functionalization of C−X (X = F, Br) bonds. This work unlocks the independent LUMO reactivity of a mesoionic compound.

Examining the inhibitory potency of metal polyphenolic network–coated silver nanoparticles against amyloid fibrillogenesis of lysozyme

There are currently over forty degenerative diseases that are correlated with abnormal accumulation of peptide/protein aggregates in the human body, such as Alzheimer’s disease. Due to their unique physiochemical properties (e.g., small size, large surface-to-volume ratio, and facile surface modification), silver nanoparticles (AgNPs) have been considered potential substrates for designing inhibitors against amyloid fibrillogenesis. Metal polyphenolic network (MPN) that combines the characteristics of organic and inorganic components has been used to suppress amyloid fibril formation. This study is aimed at investigating the effects of MPN–coated AgNPs (MPN–AgNPs) on the in vitro amyloid fibrillogenesis of hen lysozyme (HEWL). The two types of MPN–AgNPs (Zn/MPN–AgNPs and Co/MPN–AgNPs) were synthesized through chemical reduction and metal chelation, and their particle sizes were determined to be in the range of 40–60 nm. The characterization of MPN–AgNPs by ζ–potential and transmission electron microscopy showed that the MPN–AgNPs had negative surface charge and spherical-shaped morphology. Furthermore, the elemental analysis demonstrated that the MPN was uniformly coated on the surface of AgNPs. The thioflavin T fluorescence results revealed that the Co/MPN–AgNPs showed a better percent of inhibition compared to Zn/MPN–AgNPs and TA–AgNPs. The kinetics data of amyloid fibril formation in the presence of MPN–AgNPs were analyzed using the sigmoidal curve, showing that the MPN–AgNPs reduced fibril growth rate and prolonged lag time. Our findings also demonstrated that MPN–AgNPs could effectively suppress HEWL aggregation upon binding to aggregation-prone regions. The quenching of intrinsic fluorescence of HEWL by MPN–AgNPs was found to be a static type. Moreover, the fluorescence quenching data were analyzed using the modified Stern-Volmer equation to determine the number of binding sites. Notably, our findings indicated that the binding between HEWL and MPN–AgNPs was mainly governed by hydrophobic interaction. This work offers an excellent example of utilizing MPN–based materials as anti-aggregating/anti-fibrillogenic nano-drugs for the treatment of amyloidosis.

A rapid colorimetric sensor for the detection of mercury in environmental samples employing 2 aminobenzohydrazide schiff base functionalized silver nanoparticles

Mercury (Hg2+) is an extremely toxic and dangerous element for living organisms. Herein, a simple and selective sensor based on the Schiff base of 2-aminobenzohydrazide with triazole thiazole substituted vanillin (EAHT) functionalized silver nanoparticles (EAHT-AgNPs) is proposed for the detection of Hg2+ in environmental water samples. The chemical reduction method was employed to synthesize EAHT-AgNPs using sodium borohydride as the reducing agent. The synthesized nanoparticles were initially confirmed by UV-visible and FTIR spectroscopy, followed by analysis with a zeta sizer to determine their average size, surface charge and polydispersity index. The atomic force microscopy (AFM) and scanning electron microscopy (SEM) were employed to determine the size and morphology of EAHT-AgNPs. Additionally, the functionalized particles exhibited stability at varying pH values, salinity concentrations and elevated temperature. The addition of Hg2+ altered the yellow color of EAHT-AgNPs to colorless, confirming the complex formation. The analytical response constructed as a decrease in absorbance versus concentration showed linearity (R2 = 0. 991) from 0.1 to 100 µM with a limit of detection of 0.04 µM (40 nM) and limit of quantification of 0.085 µM (85 nM). The sensor was successfully applied for the detection of Hg2+ ions in tap water. In conclusion, Schiff base of 2-aminobenzohydrozide with triazole thiazole substituted vanillin silver nanoparticle-based chemosensor is highly sensitive and selective for the detection of Hg2+ in water samples. The proposed sensor has been applied for mercury detection tap water, future research should explore its applications in more complex samples like industrial wastewater and marine environments. Further, studies may focus on the integrating of the approach into the portable devices such as smartphone for on-site detection of mercury.

Mechanochemical synthesis of FeCo nanoalloys

The Iron-Cobalt Nanoalloys (ICNAs) were synthesized by co-reduction of the mixture of FeCl2.4H2O and CoCl2.6H2O salts and also in the chemical reduction of iron(II) bis(oxalate)cobaltate pentahydrate complex by aluminum nanoparticles in the solid-state at room temperature. Aluminum nanoparticles were prepared by a novel wire drawing method in the presence of lubricating oil. The products were characterized by IR, XRD, FESEM, EDX and VSM. The absorption bands do not appeared in FTIR spectra of FeCo nanoalloys (ICNAs) while, the spectra of precursor show all the absorption bands of the corresponding complex and salts. The X-ray diffraction pattern results show the presence of two phases unreacted aluminum and FeCo in ICNAs. The weight fraction of FeCo nanoparticles are calculated by the Rietveld method. Quantitative XRD analysis of FeCo-Al (S1) shows a weight fraction of 89.82% FeCo and unreacted aluminum 10.18% also, calculation in FeCo-Al (S2) shows weight fraction FeCo and unreacted aluminum 78.50 and 21.50% respectively. FESEM image of S1 and S2 show maximum particles size distribution in the region of 60nm to 100nm and 40nm to 80nm respctively. The hysteresis loop of S1 and S2 show magnetic saturation 101.8900emu/g and 39.6442emu/g respectively.

Manufacturing antibacterial Ti-6Al-4V alloys by using NanoAg particles synthesized by reduction method for biomedical applications

Titanium alloys are among the widely used biomedical materials due to their biocompatibility and mechanical performance. It is an indisputable fact that the materials used in this area must be antibacterial. Therefore, in this study, the production of antibacterial Titanium alloys using NanoAg particles for use in biomedical applications was investigated. First, Ti-6Al-4 V titanium alloys were produced by the powder metallurgy method, which includes blending, pressing and sintering processes. Nano silver particles were synthesized by a chemical reduction method using silver nitrate and glucose. The resulting solution was subjected to Ag + ions and glucose determinations, pH and turbidity analysis. Nano Ag application was carried out by two different methods; dipping and coating method. The obtained samples were analyzed by scanning electron microscopy (SEM) and optical microscopy. Additionally, as the main purpose of this study, antibacterial analysis against Escherichia Coli and Staphylococcus Aureus was performed by percentage reduction test. While the coating method was seen to be more successful in antibacterial tests, the overall Nano Ag application performance was found to be higher against Escherichia Coli bacteria. Being that the sample containing 5% Nano Ag titanium alloys produced with the coating technique showed 100% killing effect against both Staphylococcus aureus and Escherichia coli.

Heavier Diferrocenylpnictogenium Ions.

The synthesis, characterization and reactivity of the diferrocenylphosphenium ion [Fc2P]+ was extended to the heavier diferrocenylpnictogenium ions, [Fc2E]+ (E = As, Sb, Bi). The lighter diferrocenylnitrenium ion, [Fc2N]+, was detected by mass spectrometry, but could not be isolated. The molecular structures of [Fc2E]+ (E = P, As, Sb, Bi) reveal intramolecular coordination of the iron atoms, which counterbalance the electron deficiency of the pnictogens without affecting the strong Lewis acidities, which were determined according to the method of Gutmann and Beckett. The (electro-)chemical oxidation and reduction afforded the dications [Fc2E]2+ (E = P (unstable), As) and the neutral dipnictogens Fc2EEFc2 (E = P, As).

A silver lining in MRSA treatment: The synergistic action of poloxamer-stabilized silver nanoparticles and methicillin against antimicrobial resistance

BackgroundIncreasing antibiotic resistance in bacterial infections, including drug-resistant strains like methicillin-resistant Staphylococcus aureus (MRSA), necessitates innovative therapeutic solutions. Silver nanoparticles are promising for combating infections, but toxicity concerns emphasize the importance of factors like dosage, size, shape, and surface chemistry. Hence, exploring poloxamer as a stabilizing agent to reduce its toxicity and enhance the antibacterial effect on MRSA is investigated. MethodsSilver nanoparticles stabilized with poloxamer (AgNPs@Pol) were synthesized through the chemical reduction method and characterized using UV–visible spectrophotometer, HR-TEM, DLS, and Zeta potential measurements. Subsequently, the antibacterial activity of AgNPs@Pol alone and in combination with methicillin against MRSA and methicillin-susceptible S. aureus (MSSA) was evaluated using the broth microdilution method. ResultsAgNPs@Pol showed significant efficacy against MRSA and MSSA, achieving a 100 % reduction in colony-forming units (CFU) at 9.7 μg/ml. The minimum inhibitory concentration (MIC) against MRSA and MSSA was 8.6 μg/ml and 4.3 μg/ml, respectively. A synergistic effect was observed when AgNPs@Pol was combined with methicillin. Treatment with AgNPs@Pol increased reactive oxygen species (ROS) production in both strains, contributing to its antibacterial activity. Real-time qPCR analysis indicated the downregulation of genes involved in antimicrobial resistance and cell adhesion in both strains. Further, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay demonstrated low cytotoxicity for AgNPs@Pol against MCF-7, MG-63, and NIH-3T3 cell lines. ConclusionThe developed AgNPs@Pol demonstrated extensive colloidal stability, potent antibacterial activity and synergistic effect with methicillin against MRSA and MSSA. Further studies in primary cells and in vivo models may validate its potential for clinical applications.

Emerging 2D MXene quantum dots for catalytic conversion of CO2

MXene is an emerging material for converting carbon dioxide (CO2) into valuable products because of its robust physical and chemical properties. The high specific surface area (SSA), conductivity, and stability of the MXene make it an attractive material for the catalytic conversion of CO2. The pristine MXene possessed poor catalytic properties as compared to their composites. This study briefly discussed the magical properties and advanced synthesizing routes of MXene and MXene quantum dots (MQDs). In addition, the oxidation of the MXene is responsible for altering its chemical composition, and the factors used to oxidize the MXene were discussed in detail. Furthermore, the mechanism of hydrogenation, chemical, electrocatalytic, and photocatalytic reduction of CO2 has been discussed. Finally, the MXene quantum dots (MQDs) for photocatalytic conversion of CO2 for the first time also present the future challenges and prospectus associated with MXene.

Structural and magnetic properties of high magnetization FexCo100-x nanoparticles investigated at the nanoscale: Unveiling the origin of the observed anisotropy

In this work the authors have performed the synthesis of FexCo100-x (0<x<100) alloy nanoparticles (NPs) with different compositions, as well as pure Fe and Co NPs for comparison, by a chemical reduction technique. The subsequent characterization demonstrated excellent quality NPs with the expected bcc cubic (for Fe and FeCo alloys) and hcp hexagonal (for Co NPs) structures showing a room temperature magnetization as high as 235 emu/g for the Fe66Co34 composition alloy. Nevertheless, this soft magnetic character is accompanied by determined values of effective anisotropy as high as 2 MJ/m3. Aiming to deep into the properties of these FeCo alloys as well as to unveil the origin of that observed high anisotropy value, we now present an extensive study at the nanoscale of the synthesized Fe, Co and FexCo100-x alloy nanoparticles by using nuclear techniques as neutron powder diffraction, EXAFS and XANES spectroscopies. Mössbauer spectroscopy revealed that the FeCo alloys are in an A2 disordered solid solution. The obtained results, combined with AFM/MFM images, have demonstrated that despite the cubic bcc structure observed for all FeCo alloys (in excellent concordance with the pure Fe one) the NPs show a "flaky" shape of 50–60 nm size (diameter) but only 3–4 nm thickness, giving rise to a strong shape anisotropy contribution to the observed total effective anisotropy.

From [2Mn2S] Diamond Cores to Butterfly Rhombs: Transformations That Highlight Alternating Peptide Binding Sites.

Thiocarboxamide chelates are known to assemble [2Mn2S] diamond core complexes via μ-S bridges that connect two MnI(CO)3 fragments. These can exist as syn- and anti-isomers and interconvert via 16-electron, monomeric intermediates. Herein, we demonstrate that reduction of such Mn2 derivatives leads to a loss of one thiocarboxamide ligand and a switch of ligand binding mode from an O- to N-donor of the amide group, yielding a dianionic butterfly rhomb with a short Mn0-Mn0 distance, 2.52 Å. Structural and chemical analyses suggest that reduction of the Mn(I) centers is dependent on the protonation state of the amide-H, as total deprotonation followed by reduction does not result in the reduction of the Mn2 core. Partial deprotonation followed by reduction suggests a pathway that involves monomeric Mn(CO)3(S-O) and Mn(CO)3(S-N) intermediates. Ligand modifications to tertiary amides that remove the possibility of amide-H reduction led to complexes that preserve the [2Mn2S] diamond core during chemical reduction. Further comparison with the tethered system, linking the Mn(CO)3(S-O) sites together, suggests that dimer dissociation is necessary for the overall reductive transformation. These results highlight organomanganese carbonyl chemistry to establish illustrations of peptide fragment binding modes in the uptake of low-valent metal carbonyls related to binuclear active sites of biocatalysts.

Synthesis of Nanoparticles for Drug Delivery in Korea

Purpose: The aim of the study was to assess the synthesis of nanoparticles for drug delivery in Korea. Methodology: This study adopted a desk methodology. A desk study research design is commonly known as secondary data collection. This is basically collecting data from existing resources preferably because of its low cost advantage as compared to a field research. Our current study looked into already published studies and reports as the data was easily accessed through online journals and libraries. Findings: The study indicated that the synthesis of nanoparticles for drug delivery has emerged as a promising strategy to enhance the efficacy and precision of therapeutic interventions. Nanoparticles offer several advantages, such as improved bioavailability, targeted delivery, and controlled release of drugs. Various methods are employed in their synthesis, including chemical reduction, sol-gel processes, and biological methods using natural organisms. These nanoparticles can be engineered to carry a wide range of drugs, including chemotherapeutics, antibiotics, and vaccines. Their small size allows them to navigate biological barriers and deliver drugs directly to specific tissues or cells, reducing side effects and improving treatment outcomes. However, challenges such as scalability, toxicity, and regulatory hurdles remain, necessitating further research to optimize their clinical applications. Implications to Theory, Practice and Policy: Brownian motion theory, nanoscale phenomena theory, thermodynamic theory of nanoparticle stability may be used to anchor future studies on the synthesis of nanoparticles for drug delivery in Korea. Practitioners in the field should prioritize the enhancement of synthesis techniques and the focus on biocompatibility and safety to improve the practical applications of nanoparticle drug delivery systems. To ensure the safe and effective use of nanoparticles in drug delivery, policymakers must establish clear guidelines and regulations governing their application.

Refining habitat selection for sulfate-reducing bacteria: Evaluating suitability and adaptability for sulfate-metal wastewater treatment during anaerobic-to-aerobic transitions

Inoculating sulfate-reducing bacteria (SRB) habitats offers an eco-friendly method for treating sulfate-metal laden wastewater, characterized by high sulfate levels, low pH, and elevated heavy metals. This study optimizes source habitat selection of SRB by evaluating groundwater, sewage sludge, and lake sediment, focusing on their suitability and adaptability to aerobic-anaerobic transitions in industrial settings. Sewage sludge, with its slightly acidic pH, reducing environment, and high nutrient levels (Total organic carbon: 207.53 g kg−1, Total nitrogen: 47.12 g kg−1), provides robust SRB potential, as supported by its highest diversity index. However, heavy metals and polycyclic aromatic hydrocarbons pose application challenges. All habitats effectively reduced metal concentrations anaerobically, with Cu removal reaching 95%–99%, and groundwater achieved the highest chemical oxygen demand reduction (63.6%) aerobically. Sludge and sediment showed high biomass and extracellular polymeric substances (EPS) accumulation, while groundwater's nucleic acid-rich EPS enhanced metal immobilization, resulting in stable residual metal forms but with potential remobilization under oxidative conditions. Microbial analysis revealed that Proteobacteria and Firmicutes were key players during transitions, with the highest SRB abundance in groundwater. SRB composition varied across habitats, with Sedimentibacter (13.04%), Desulfovibrio (6.33%), and Desulfomonile (8.1%) dominating in groundwater, sludge, and sediment, respectively, during the anaerobic stage. Functional analysis highlighted sludge's persistence in sulfate reduction under aerobic conditions, while groundwater's limited nitrogen cycle involvement indicated broader biogeochemical limitations. Collectively, these findings highlight strengths and limitations of each habitat as SRB inoculum source, emphasizing the importance of tailored anaerobic-to-aerobic strategies for effective wastewater management.

Redox factors in the antioxidant activity of nitroxides toward DNA guanyl and 2-deoxyribose-peroxyl radicals

A series of eight nitroxide compounds (four substituted piperidines, three pyrrolidines and one oxo-piperidine) are found to undergo electron transfer to 2’-deoxyribose-peroxyl and the guanyl radical. One-electron oxidation potentials of the nitroxides to oxoammonium cations (oxoammonium reduction potential), E 0’, have been measured against a common redox indicator, chlorpromazine, and found to span the range 751 ± 15 mV to 973 ± 15 mV. Fast chemical reduction of the 2’-deoxyribose-peroxyl radical to the hydroperoxide, generated by • OH radical attack on 2-deoxyribose, dR, in oxygenated aqueous solution, is a redox-dependent reaction, with rate constants of 0.8–3.5 x 107 M−1 s−1.The guanyl radicals, produced upon one-electron oxidation of 2’-deoxyguanosine monophosphate, dG, by the selenite radical, SeO3 • -, react with the nitroxides in a redox-independent reaction with diffusion rate constants of 1–2 x 108 M−1 s−1. These findings represent a possible antioxidant role for nitroxides in the fast chemical repair of DNA radicals, which is supported by an in vitro strand break study using a plasmid.

AgNPs break the wall cell in Chlorella vulgaris by oxidative stress generation

Silver nanoparticles are used commercially due in part to its antibacterial power. However, due to their nanoscale size, these may not be retained by filters wastewater reaching the aquatic environment, which could affect microorganisms of initial food-chain as microalgae. The purpose of this study was to elucidate the cytotoxic effects of silver nanoparticles (3-7nm) in freshwater phytoplankton (Chlorella vulgaris) ex situ. Silver nanoparticles synthesis was performed according to silver nitrate chemical reduction, they were characterized by scanning electron microscope. C. vulgaris collected from Chapala Lake, Jalisco, México, was kept under laboratory conditions. C. vulgaris, grown in Bristol broth, were exposed to different concentrations of silver nanoparticles (0.01, 0.1 and 1mg L-1) for 24 hours. An important cytotoxic effect was determined in C. vulgaris exposed to silver nanoparticles, manifested by decrement in Chlorophyll-a contents, morphological changes, prominent perforations in cell walls, important decrement of lipid contents and oxidative stress generation, that corresponding to the nanoparticle concentration.

Synthesis of Silver Nanoparticles and Forced Convective Heat Transfer Coefficient Measurement of Silver-Water Nanofluids at Laminar Flow

Heat management in industries and other areas is a major issue currently worldwide. Conventional heat transfer fluids like water and ethylene glycol are not very effective. Nanofluids (NFs), composed of nanoparticles (NPs) dispersed throughout a base fluid (BF), have recently been identified as promising heat management agents for various industrial and other applications. Heat transmission is one of the many uses for AgNPs–water NFs (silver NPs (AgNPs) dispersed in water). The goal of this work was to determine the AgNPs–water NFs' forced convective heat transfer coefficient (HTC) in laminar flow. Due to this, we present the results of the HTC study of AgNPs–water NFs in laminar flow in this paper. First, using AgNO3 as a precursor, a chemical reduction approach was used for facile synthesis of AgNPs in one pot at ambient temperature. Synthesized NPs were examined using ultraviolet-visible spectroscopy (UV-vis), X-ray diffraction (XRD), and transform electron microscopy (TEM) techniques. The average particle size obtained from TEM is 25 nm. The required quantity of AgNPs was added to the water to produce 0.5 and 1.0 vol% of AgNPs–water NFs. Next, zeta potential and dynamic light scattering (DLS), in addition to time-lapse observation and captured picture comparison, were used to assess the stability of the formulated NFs. To calculate the forced convective HTC of prepared NFs in laminar flow, a vertical shell and tube heat transfer apparatus and computer-based data recorder were used. According to the results, in comparison to BF, the HTC of 0.5 and 1.0 vol% NFs was 3.3 and 5 times greater, respectively which encourages the use of AgNPs–water NFs in industry and other heat management. Jagannath University Journal of Science, Volume 11, Number 1, June 2024, pp. 13−22

Differences in slow-release characteristics and release kinetics of three selenium nanoparticles from different synthesis strategies: Revealing the advantages synthesized by Lactiplantibacillus plantarum

The controlled release of selenium nanoparticles (SeNPs) is pivotal significance in improving bioavailability and mitigating potential side effects. Three types of SeNPs, Selenium nanoparticles synthesized by chemical method (CSeNPs), extracellular polysaccharide-encapsulated selenium nanoparticles (EPS-SeNP), and selenium nanoparticles synthesized by Lactiplantibacillus plantarum (LacSeNPs), were synthesized in this study using chemical reduction, polysaccharide-assisted, and microbial reduction methods, respectively. The selenium release kinetics of the nanoparticles were investigated in simulated gastrointestinal with five kinetics models. CSeNPs released 67.80% of selenium in simulated gastric fluids (SGF) and, depicting a Brownian motion fraction of 81.0. EPS-SeNPs released 77.38% of selenium in SGF while only releasing 16.28% in simulated intestinal fluids (SIF). The release process was primarily affected by changes in the nanoparticle structure after Super Case II Transport in SGF and the zero-order model in SIF. The zero-order model provided the best fit for releasing LacSeNP profiles in the SGF. In SIF, the release mechanism of LacSeNPs was regulated by combination of diffusion and carrier swelling or erosion, leading to non-Fickian diffusion. Therefore, synthetic nanoparticle methods determine their structures and compositions, leading to differences in their release kinetics and release mechanisms. Notably, the release of LacSeNPs in the SGF aligns with the absorption patterns of selenium within the human body. The current study elucidates the potential application advantages of SeNPs synthesized using microbial means as selenium-enriched supplements.

Facile Access to Phosphorus Ylide‐fused Heteroarenes Possessing Tunable Optoelectronic Properties and High Nonlinear Optical Performances

We report here a novel family of ylidic P‐heteroarenes (P1‐P6), structurally featuring unique phosphonium cyclopentadienylide (P‐Cp)‐fused π‐skeletons and synthetically prepared via an unexpected one‐pot [2+3]/[3+3] phospha‐annulation reaction. While the facile and modular synthesis allows the fine‐tuning of their optical absorptions and redox properties, single‐crystallographic and theoretical analysis of these P‐heteroarenes further reveal that the fusion of P‐Cp moiety leads to substantial intramolecular charge‐separated features with high ylidic character values of up to 84%. Benefitted from such dipolar structures, these P‐heteroarenes not only allows stepwise electrophilic substitution reaction for further structural π‐expansions, but also exhibit excellent nonlinear optical (NLO) responses and optical limiting (OL) performances comparable to or exceed those of C60. As a model compound, the persistent radical‐anion salt of P5a was also prepared through chemical reduction, thus offering valuable insights into the electronic structures of reduced P‐ylidic species. Our work not only established a highly efficient synthetic method toward new P‐heteroarenes, but also provide fundamental understanding of those fused‐ring ylidic P‐heterocycles with promising NLO/OL applications.