Enhancement Factor Research Articles

Hollow Gold-Silver Nanorods-A New, Very Efficient Nanomaterial for Surface-Enhanced Raman Scattering (SERS) Measurements.

Anisotropic plasmonic nanoparticles usually generate SERS enhancement factors that are significantly larger than those generated by spherical plasmonic nanostructures, so the former are usually preferred as substrates for SERS measurements. Gold nanorods are one of the most commonly used anisotropic nanomaterials for SERS experiments. Unfortunately, even a slight contamination of the surfactant used in the process of the synthesis of gold nanorods has a significant impact on the geometry of the resulting nanostructures. In this work, using easily formed silver nanorods as templates, hollow AuAg nanorods are formed by means of a silver-gold galvanic exchange reaction (in this process, nanostructures with a cavity inside form because one gold atom replaces three silver atoms). Hollow AuAg nanorods are highly active during SERS measurements-for shorter wavelengths of the excitation radiation, they display greater SERS activity than Au nanorods. To our knowledge, this is the first example of the use of hollow plasmonic nanorods for SERS measurements. Elemental mapping of the rods showed that the silver, some of which remained after the galvanic replacement, is mainly located close to the internal cavity that was formed, whereas the gold is mainly located at the outermost regions of the nanostructure. This explains the high chemical stability of these nanostructures.

Photoinduced Charge Transfer Empowers Ta4C3 and Nb4C3 MXenes with High SERS Performance.

This study introduces two-dimensional (2D) Ta4C3 and Nb4C3 MXenes as outstanding materials for surface-enhanced Raman scattering (SERS) sensing, marking a significant departure from traditional noble-metal substrates. These MXenes exhibit exceptional SERS capabilities, achieving enhancement factors around 105 and detection limits as low as 10-7 M for various analytes, including environmental pollutants and drugs. The core of their SERS functionality is attributed to the robust interfacial photoinduced charge-transfer interactions between the MXenes and the adsorbed molecules. This deep insight not only advances our understanding of MXene materials in SERS applications but also opens new avenues for developing highly sensitive and selective SERS sensors. The potential of Ta4C3 and Nb4C3 MXenes to revolutionize SERS technology underscores their importance in environmental monitoring, food safety, and beyond.

Femtosecond laser-induced black silicon: a dual application in photodetection and surface-enhanced Raman scattering

A multifunctional structured silicon with enhanced optical and photoelectric properties has been processed by femtosecond (fs) laser in ambient air. The structured surface decorated with Au nanoparticles (NPs) exhibits excellent infrared absorption properties related to localized surface plasmon resonance (LSPR) coupled to microstructures. Over 75% absorption is achieved at 1550 nm, which is three orders of magnitude higher than that of unprocessed Si. The absorption enhancement results in increased photocurrent response in n + -n junction diodes, exhibiting a responsivity of 125 mA/W and an external quantum efficiency (EQE) of 10% at 1550 nm, for a bias voltage of 10 V. Moreover, the structured Si is also tested as a surface-enhanced Raman spectroscopy (SERS) substrate showing a strong signal under 638 nm excitation with Raman enhancement factors (EFs) as high as 108. In particular, the capability of detecting Raman analyte down to 10−11 M for RhB and 10−10 M for 4-MBA is demonstrated, simultaneously assessing the enhanced near-field due to the LSPR originating from the processed surface roughness leading to the valuable performances achieved by the n + -n junction diodes. These results offer a new path toward the elaboration of high-efficiency applications of Si structured surfaces in the fields of photoelectric sensing and detection.

Pre- and Postsynaptic MEF2C Promotes Experience-Dependent, Input-Specific Development of Cortical Layer 4 to Layer 2/3 Excitatory Synapses and Regulates Activity-Dependent Expression of Synaptic Cell Adhesion Molecules.

Experience- and activity-dependent transcription is a candidate mechanism to mediate development and refinement of specific cortical circuits. Here, we demonstrate that the activity-dependent transcription factor myocyte enhancer factor 2C (MEF2C) is required in both presynaptic layer (L) 4 and postsynaptic L2/3 mouse (male and female) somatosensory (S1) cortical neurons for development of this specific synaptic connection. While postsynaptic deletion of Mef2c weakens L4 synaptic inputs, it has no effect on inputs from local L2/3, contralateral S1, or the ipsilateral frontal/motor cortex. Similarly, homozygous or heterozygous deletion of Mef2c in presynaptic L4 neurons weakens L4 to L2/3 excitatory synaptic inputs by decreasing presynaptic release probability. Postsynaptic MEF2C is specifically required during an early postnatal, experience-dependent, period for L4 to L2/3 synapse function, and expression of transcriptionally active MEF2C (MEF2C-VP16) rescues weak L4 to L2/3 synaptic strength in sensory-deprived mice. Together, these results suggest that experience- and/or activity-dependent transcriptional activation of MEF2C promotes development of L4 to L2/3 synapses. Additionally, MEF2C regulates the expression of many pre- and postsynaptic genes in postnatal cortical neurons. Interestingly, MEF2C was necessary for activity-dependent expression of many presynaptic genes, including those that function in transsynaptic adhesion and neurotransmitter release. This work provides mechanistic insight into the experience-dependent development of specific cortical circuits.

Cholecystokinin regulates atrial natriuretic peptide secretion through activation of NOX4–Sirt1–LEF1 signaling in beating rat hypoxic atria

The mammalian cardiac myocytes not only synthesize and secrete atrial natriuretic peptide (ANP), but also express cholecystokinin (CCK) and its receptors (CCK1R and CCK2R). However, atrial CCK expression patterns and its effects on ANP secretion during hypoxia are unclear. Therefore, this study is aimed to investigate the effect of hypoxia on the expression levels of CCK and its receptors, as well as the underlying mechanisms involved in regulating hypoxia-induced ANP secretion in isolated beating atria. The results of this study showed that acute hypoxia significantly upregulated expression of CCK and CCK1R as well as CCK2R through activation of hypoxia-inducible factor 1α–apelin signaling. Endogenous CCK induced by hypoxia markedly upregulated the expression of silent information regulator factor 2-related enzyme 1 (Sirt1) and its downstream nuclear factor erythroid‑2‑related factor 2 (Nrf2) via the activation of nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4), leading to increase of activating T cell factor (TCF) 3 and TCF4/ lymphoid enhancer factor (LEF) 1, ultimately promoting hypoxia-induced ANP secretion. In addition, siRNA-mediated knockdown of LEF1 dramatically attenuated hypoxia-induced increase of ANP expression in HL-1 atrial myocytes. These results indicated endogenous CCK induced by hypoxia promoted hypoxia-induced ANP secretion by activation of NOX4–Sirt1–TCF3/4–LEF1 signaling pathway.

Ecofriendly Filtration of Silver Nanoparticles for Ultrasensitive Surface-Enhanced (Resonance) Raman Spectroscopy-Based Detection.

In this study, a widely used colloid of Creighton AgNPs (ORI, 1-100 nm, mostly ≤ 40 nm, ∼10 μg mL-1) was rapidly manipulated via tangential flow filtration (TFF) for highly reproducible surface-enhanced (resonance) Raman spectroscopy (SE(R)RS) experiments down to the single-molecule (SM) level. The quasi-spherical AgNPs were size-selected, purified, and concentrated in two TFF fractions of a cutoff diameter of ∼40 nm: AgNP ≤ 40 (∼900 μg mL-1) and AgNP ≥ 40 (∼100 μg mL-1). The SE(R)S-based sensing capabilities of the two TFF fractions were then tested under pre-resonance (632.8 nm) and resonance (532.1 nm) excitation conditions for rhodamine 6G (R6G, 10-6-10-15 M). Both TFF isolates, AgNP ≤ 40 and AgNP ≥ 40, were more effective in adsorbing the R6G analyte (≥91%) than the original colloid (≥78%) at submonolayer coverages. Furthermore, the surface enhancement factors (SEF) of the two TFF fractions were markedly superior to those of ORI under all excitation conditions. SERS at 632.8 nm: only AgNP ≥ 40 enabled the detection of R6G at 10-9 M and produced the largest SEF (2.1 × 106). SE(R)RS and SM-SERRS at 532.1 nm: AgNP ≥ 40 gave rise to the largest SEF values (2.5 × 1010) corresponding to the SM regime down to 10-15 M of R6G. Nevertheless, AgNP ≤ 40 compensated for the size-dependence of the electromagnetic enhancements by an increase in the silver concentration, which led to SEF values comparable to those of AgNP ≥ 40 through additional resonance enhancements. TFF resulted into a ∼100-fold increase (AgNP ≤ 40) in the number of negatively charged AgNPs that were available to electrostatically bridge R6G cations and form SERRS "hot-spots" (AgNP-R6G-AgNP) within the focal volume. Evidently, the interplay between AgNP size, AgNP concentration, and excitation wavelength governs the SE(R)RS enhancements. This study demonstrated that TFF can facilitate the ecofriendly isolation of spherical AgNPs of controlled morphological and plasmonic properties for further enhancing their sensing capabilities as SE(R)RS substrates.

Numerical Investigation of Shell-Nozzle Diameter Effect on Thermal Performance of Shell-and-Tube Heat-Exchanger

The shell nozzle diameter plays a crucial role in determining heat transfer efficiency and pressure characteristics in shell and tube heat exchangers. In this study, we have conducted a numerical simulation to explore the effects of varying shell nozzle diameters on heat transfer performance, flow behavior, and pressure drop within a shell and tube heat exchanger. Ranging from 10 to 110 mm, we assessed how altering the shell nozzle diameter affected heat transfer, flow patterns, and pressure drop. Employing the k-ω shear stress transport turbulence model, we compared numerical Nusselt numbers to experimental data, observing a correlation. As the shell nozzle diameter decreased, inlet velocity surged, generating a stronger vortex. Shrinking from 110 to 10 mm, this reduction amplified vorticity by an average of 169%, notably intensifying heat exchange by 35%. Evaluating the overall heat transfer coefficient against pressure drop, we used the thermal enhancement factor, reaching a peak of 4.39 at a 70 mm shell nozzle diameter. This exploration lays groundwork for optimizing shell nozzle diameters in these heat exchangers.

A novel MOF-derived Fe/Ce@NPC-600 floating cathode with massive FeII using in photoelectro-Fenton system for efficient degradation of aqueous tetracycline: Fabrication, performance prediction based on machine learning and mechanism

A MOF-derived carbon/metaloxide composite (Fe/Ce@NPC-600) by doping Ce into NH2-MOF-101(Fe) precursor and simple one-step carbonization was fabricated. Fe/Ce@NPC-600 as a floating cathode was innovatively applied to the solar photoelectro-Fenton (SPEF) process to increase the yield of H2O2 and activate it for degradation tetracycline (TC). The characterizations showed that the presence of Ce greatly increased the content of Fe2+ and photoresponse ability in the material. Thanks to the synergistic effect of Fe and Ce, Fe/Ce@NPC-600 cathode could efficiently degrade TC by 98.2% within 30 min, and the removal rate of total organic carbon (TOC) was 68.2%, and the photoelectric synergistic enhancement factor (fPEF) was 1.4. Besides, based on machine learning, a extreme gradient boosting model was established to predict electrode performance. The degradation mechanism and pathway of TC were also proposed. Our results inspired the application of floating cathodes, MOF-derived materials and artificial intelligence for advanced oxidation processes for efficient removal of emerging contaminants.

High-Volume Production of Repeatable High Enhancement SERS Substrates Using Solid-State Superionic Stamping

Abstract Surface-enhanced Raman spectroscopy (SERS) is emerging as a powerful tool for detecting and identifying chemical and biological substances because of its high sensitivity, specificity, speed, and label-free detection. For SERS substrates to be effective in sensing applications, they must exhibit reproducible and robust high signal enhancement and cost-effective scalability. This article introduces a highly sensitive, large-area silver SERS substrate patterned with a uniform array of 3D retroreflecting inverted pyramids and develops a manufacturing pathway for it, using a novel and facile electrochemical imprinting process called solid-state superionic stamping (S4). Substrates, approximately 4 mm2 in area, are produced and tested with 1,2-bis(4-pyridyl) ethylene (BPE). Uniformly high and reproducible spatially averaged enhancement factor (EF), typically around a value of 2 × 107 with a relative standard deviation of 6.7% and a high batch-to-batch repeatability with a relative standard deviation of 10.5% between batches were observed. Passivating a substrate's surface with atomically thin layers of alumina, deposited using atomic layer deposition (ALD) was effective in maintaining the EF constant over a 60-day period, albeit with a trade-off between its EF and its lifespan. S4 has the potential to make substrates with EF consistently greater than 107 available at a cost of $1 to $2 per substrate, allowing SERS to be adopted across a wide spectrum of high-volume applications, including security, food safety, medical diagnostics, and chem-bio analysis.

Effects of corrugation on convective heat transfer and power generation in a wavy walled triangular cavity equipped with inclined elastic fin and piezo-energy harvester assembly

Piezoelectric energy harvesters are one of the energy conversion technologies that can be used to convert a variety of external sources, including wind, fluid motion, and vibrations, into electrical energy. This work suggests a novel wall corrugation design in addition to an elastic fin piezo assembly arrangement for power generation and thermal management in a triangular cavity during turbulent forced convection of air. Using the finite element method with ALE, the analysis is conducted for different values of fin inclination (γ between 0 and 60), corrugation amplitude (Af between 0.01H and 0.06H), corrugation frequency (Nf between 1 and 20) and fin distance from the mid-point of the inclined wall in wall direction. The average Nusselt number (Nu) and generated power (PW) show a non-linear increasing trend with increasing fin tilt. Average Nu increment factor becomes 5.17 with the highest fin inclination while the power increments become 11.6 and 4.46 when rising inclination from 30 to 45 and from 45 to 60. The generated power rises with higher corrugation amplitude and wave number. However, increasing the wave number results in thermal performance degradation. Increment of average Nu becomes 1.17 with highest corrugation amplitude while it declines by a factor of 10.3 at the highest wave number. Power enhancement factors of 5.73 and 2.32 are obtained by increasing the corrugation amplitude from Af = 0.0714H to Af = 0.1786H and from Af = 0.1786H to Af = 0.2143H. When fin positions sf = 0.7143H and sf = -0.7143H are compared with the case of fin location at sf = 0, the power increment factors become 12.27 and 4.76, respectively. For the power produced by the piezo device, a polynomial type correlation is suggested by adjusting the parameters of the corrugated wall.

Comparative Analysis of Two Different MIM Configurations of a Plasmonic Nanoantenna

AbstractTwo plasmonic nanoantenna configurations—nanodisk and nanostrip arrays—in a metal–insulator-metal (MIM) setup were proposed, optimized, and compared by simulating their optical properties in three-dimensional models using COMSOL Multiphysics software. The optical responses, including electric field enhancement, absorption, reflection, and transmission spectra, were systematically investigated. Optimized geometrical parameters led to a significant enhancement of the electric field within the gap layers and almost perfect light absorptance for both structures. The results showed that the enhancement of the electric field depends on the polarization of the incident light. For both polarizations, the periodic circular nanodisk array showed a stronger field enhancement with an electric field enhancement factor of 6.6 × 106 and TE polarization, and a larger absorptance of 98% at its dipole resonance wavelength, indicating the fundamental plasmonic mode. In addition, weaker resonant modes were observed in the absorptance and reflectance spectra of both nanostructures, with the nanostrips exhibiting sharper and stronger higher-order modes, making them suitable for applications requiring precise wavelength selectivity and narrow-band responses. Despite their different geometric shapes, both structures exhibited similar optimized metal film thickness and nanoparticle height, comparable modes in number and position, and identical optimized light incidence angles. Furthermore, increasing the dielectric gap layer thickness and optimizing it to a specific value revealed its ability to measure the refractive index, making it a promising candidate for sensing applications.

A semiconductor SERS sensor of corrosion-resistant PPy/GO composite film by electrochemical growth for detecting crystal violet residues in fresh fish tissue

Crystal violet (CV) residues in Marine food have produced a severe health threat in human life. In this study, we proposed a semiconductor surface-enhanced Raman scattering (SERS) sensor of corrosion-resistant Polyaniline/Graphene oxide (PPy/GO) film by electrochemical growth method to detect CV residues in fresh fish tissue. A PPy/GO dispersion solution was one-step deposited on a stainless steel sheet surface by electrochemical polymerization process to form a PPy/GO composite film acting as a semiconductor SERS substrate. Since the substrate of PPy/GO film was mainly composed of GO sheet without other metals, it had a good corrosion resistance. The SERS enhancement factor and charge transfer intensity PCT of PPy/Go SERS substrate for CV molecules were up to 1.18 × 106 and 0.903, respectively. Furthermore, the limit of detection (LOD) of PPy/GO SERS substrate could reach 1.58 nM. In addition, SERS sensor of PPy/GO film could identify CV residues in fresh fish tissues, and its recovery rate was 91.8 %–107 %. This preparing method and detecting method we proposed PPy/GO SERS substrate provide a new pathway for detecting CV residues in Marine food.

Computational modelling and optimization of physicochemical absorption of CO2 in rotating packed bed

AbstractThe current study developed a novel computational fluid dynamics (CFD) model that accounted for both physical and chemical absorption in the multiphase flow and captured the relative dominance of chemical absorption over physical by employing a tunable model parameter ‘enhancement factor’. The CFD model was validated against experimental data in a rotating packed bed, and then the validated model was used to investigate the effect of operational parameters such as rotational speed, monoethanolamine (MEA) concentration, inlet velocity, and MEA‐packing contact angle on the physiochemical absorption. The significance of each operational parameter was then evaluated by the ANOVA analysis, which inferred that the enhancement factor is sensitive to rotational speed, MEA concentration, inlet velocity, and contact angle. The p‐value of MEA concentration and inlet velocity was less than 0.05, which implies that these two variables are the most significant variables for the chemical absorption of CO2. The response surface methodology (RSM) and the artificial neural network (ANN) were also employed to develop the predictive model for the enhancement factor. Among the employed techniques, ANN resulted in R2 closer to 0.99 and could better predict the enhancement factor. The modelling approach and findings of the current study are useful in optimizing the operation of rotating packed‐bed reactor (RPB) for CO2 absorption on the industrial scale.

Desıgn of quantum-dot semiconductor optical amplifiers wıth near-zero linewidth enhancement factor

The linewidth enhancement factor (LWEF) of a semiconductor optical amplifier (SOA) quantifies refractive index fluctuations in the gain medium, which induce phase distortion in the amplified optical signal. Optoelectronic systems employing SOAs with high LWEFs often exhibit poor device stability and beam coherence. Thus, designing SOAs with low LWEF is imperative. Recently, Quantum-Dot (QD) SOAs have emerged as a solution for LWEF suppression due to quantum-confinement effects enabling tunability of the QD carrier density and emission frequency. In this study, we aim to design a composite active region comprised of a host medium and the embodied QDs, to explore the corresponding LWEF variation and propose the ultimate design strategy to achieve near-zero LWEF in QD SOAs for enhancing device stability and beam coherence. Our approach entails modeling the refractive index of the composite active region using effective medium approximation via Maxwell–Garnett mixing formulation. We then extensively tune key SOA parameters, including QD carrier density, QD emission frequency, and the collision-time constant of the carriers to uncover the optimal configuration for minimizing the LWEF. Based on empirical values, we have developed and validated a simple yet effective algorithm that precisely simulates LWEF behavior in response to changes in key QD SOA parameters. This approach offers a straightforward model for estimating LWEF variation, and its corresponding minimization in QD SOAs without requiring complex experimental measurement techniques.

A capsule phase microextraction protocol combined with GC–MS/MS for the determination of polychlorinated biphenyls in water samples

Due to the adverse effects of polychlorinated biphenyls (PCBs) on human health and ecosystems, their careful monitoring is necessary. In this work, capsule phase microextraction (CPME) combined with gas chromatography-tandem mass spectrometry (GC–MS/MS) was used to extract and determine eight PCBs in water samples. As an extraction device for the CPME procedure, two permeable microporous polypropylene tubes were employed. They contained sol–gel carbowax 20 M (sol–gel CW 20 M) sorbent and a cylindrical magnet. The adsorption and desorption conditions (i.e., type of capsule, sample volume, extraction time, stirring rate, ionic strength, type and volume of eluent, and desorption time) of the microextraction procedure were studied. Under optimum conditions, the extraction was achieved within 20 min using 20 mL of sample at a stirring rate of 1000 rpm, while the elution was performed by immersing the CPME device in 500 μL of acetone for 5 min. Accordingly, the analytical method was validated in terms of linearity, sensitivity, selectivity, enhancement factor, accuracy, and precision, and its greenness and applicability were evaluated. The obtained limits of quantification were equal to 0.010–0.050 μg L−1. The relative recoveries were equal to 91.4 and 110.6 % for intra-day and 88.0–111.2 % for inter-day study, while the relative standard deviation values were better than 10.9 %. Finally, the developed method was used for the analysis of real water samples, proving good fitness-for-purpose.

Relative fuel property variation of gas-pressurized and conventional torrefaction for biochar performance assessment

Exploring biochar from gas-pressurized torrefaction for solid biofuel production is of great concern for the process performance assessment. This study conducts several relative indexes of biochars produced from gas-pressurized and conventional torrefaction, identifying the merits of the former. The results suggest that a higher pressure is more feasible for reducing biochar volume and enhancing energy efficiency. The results of the relative higher heating value (1.01–1.07) and relative enhancement factor (1.00–1.06) indicate that gas-pressurized torrefaction is more efficient for energy density improvement. Furthermore, gas-pressurized torrefaction dramatically facilitates biochar grindability, with the relative Hardgrove grindability index value ranging from 1.20 to 2.40. The proximate and elemental analysis results suggest that a higher pressure facilitates biochar carbonization and deoxygenation with a higher carbonized component. The energy consumption, efficiency, and expense calculation results imply that gas-pressurized torrefaction is more energy-efficient and cost-saving, with the relative upgrading energy index range of 1.00–1.12.

Comprehensive analysis of charge carriers dynamics through the honeycomb structure of graphite thin films and polymer graphite with applications in cold field emission and scanning tunneling microscopy

Polymer graphite electron sources have performed satisfactorily as field emission emitters and scanning tunneling microscopy probes in the past few years. However, the emission process was characterized by limited total emission currents. This paper introduces the elemental, vibrational, electronic structure, and optical analysis of polymer graphite and glass-graphite composite field emission cathodes to study these limitations. Moreover, the field emission characteristics are studied including the changes in the potential energy barrier of the used materials and structures. Among the studied structures, the cathodes prepared from graphite thin films deposited on a micropointed glass substrate (film-GMF) showed superior performance as random field emission arrays. This includes obtaining much higher emission current values ≈ 20 times) and lower threshold voltages ≈ 1/2) compared to the results obtained from polymer graphite samples. The enhancement factor in such emitters is believed to be the three-dimensional honeycomb structure of graphite. Moreover, the study includes applying graphite coatings to tungsten nano-field emission cathodes and scanning tunneling microscopy probes, which improves the performance of such cathodes/probes in both microscopic techniques.

Magnetic-responsive sensors based on polydopamine macromolecules for highly sensitive detection of trace food colorant residues

As a kind of unique biomimetic macromolecule, polydopamine (PDA) have prominent in-situ reduction ability and interfacial adhesion. In this work, combined with in-situ reduction ability of PDA and excellent magnetic response performance of nickel foam (NF), a strategy was designed to fabricate a series of NF@PDA@AgNPs as magnetic-responsive surface enhancement Raman scattering (SERS) substrates for highly sensitive Rhodamine B (RhB) detection in chili powder. With crystal violet (CV) as probe molecule, the detection limit of SERS substrate could achieve 10−10 M, and the enhancement factor was as high as to 2.22 × 107. In addition, the NF@PDA@AgNPs SERS substrates showed excellent magnetic separation efficiency, good SERS uniformity and storage stability. More importantly, these substrates could achieve highly efficient collection and sensitive detection of RhB residues in chili powder by magnetic adsorption method, and the detection of limit was as low as to be 10−6 g/g. These NF@PDA@AgNPs substrates would be a great prospect for rapid and efficient pernicious contaminant detection in the chemical and biological fields.

Optimization of parameters for image denoising algorithm pertaining to generalized Caputo-Fabrizio fractional operator

The aim of the present paper is to optimize the values of different parameters related to the image denoising algorithm involving Caputo Fabrizio fractional integral operator of non-singular type with the Mittag-Leffler function in generalized form. The algorithm aims to find the coefficients of a kernel to remove the noise from images. The optimization of kernel coefficients are done on the basis of different numerical parameters like Mean Square Error (MSE), Peak Signal-to-Noise Ratio (PSNR), Structure Similarity Index measure (SSIM) and Image Enhancement Factor (IEF). The performance of the proposed algorithm is investigated through above-mentioned numeric parameters and visual perception with the other prevailed algorithms. Experimental results demonstrate that the proposed optimized kernel based on generalized fractional operator performs favorably compared to state of the art methods. The uniqueness of the paper is to highlight the optimized values of performance parameters for different values of fractional order. The novelty of the presented work lies in the development of a kernel utilizing coefficients from a fractional integral operator, specifically involving the Mittag-Leffler function in a more generalized form.

Multifunctional SERS Substrate for Simultaneous Detection of Multiple Contaminants and Photothermal Removal of Pathogenic Bacteria.

In this work, a boric-acid-modified Fe3O4@Au@BA-MOF composite material as a multifunctional SERS substrate was ingeniously constructed for detecting both pathogens and antibiotics as well as photothermally inactivating the pathogens. Through improving the dispersity and stability of gold nanoparticles (Au NPs), leveraging the specificity of boric acid (BA) groups in recognizing cis-diol structures, and the ability of SERS technology to provide unique fingerprint spectra of targets, the sensitive and stable detection of pathogens and antibiotics was achieved. Compared with Au NPs and Fe3O4@Au, the SERS enhancement factor of Fe3O4@Au@BA-MOF was 4.31 × 106, which was about 400 times and 16 times higher than the former two, respectively. Among the existing work, the limit of detection for pathogens was lower or comparable, and it exhibited good stability, maintaining consistent performance for 23 days. Additionally, this substrate achieved efficient photothermal inactivation of pathogens under both near-infrared light and natural light excitation. Within 8 min of near-infrared light irradiation, the bactericidal rates for Staphylococcus aureus and Escherichia coli reach 100% and 99.3%, respectively.