Total Reflection Research Articles

Observation of the Goos-Hänchen shift in monolayer WSe2 for an arbitrary linearly polarized incident light beam using weak measurement

We report, to our knowledge, the first experimental investigation of the spatial Goos-Hänchen (GH) shift at an absorbing material interface comprised of monolayer (ML) tungsten di-selenide (WSe2) on a SiO2/Si substrate under a total internal reflection (TIR) condition. The critical angle for this design is drastically shifted to 23.31°, compared to the glass-air interface, which was at 41.3°. Utilizing the weak value amplification (WVA) approach, the behavior of spatial GH shifts at this interface with various regulating parameters such as angle of incidence, polarization angle, and post-selection angle has systematically been studied. At critical incidence, the greatest shift of approximately 116 µm exceeds the maximum limit of beam shift w0/2, where w0 is the beam waist (180 µm). A generic theoretical model compatible with polarization-dependent studies is also established that has demonstrated excellent agreement with experimental results. Moreover, this work established three distinct features that allow us to readily tweak the value of spatial GH shifts. The observation of a controllable spatial GH shift at the ML WSe2-SiO2/Si configuration has potential implications for optical sensors, optical differential operation, and other photonic manipulations.

Attenuated Total Reflection Fourier Transform Infrared Spectroscopy and Chemometrics for the Discrimination of Animal Hair Fibers for the Textile Sector

Analyzing the composition of animal hair fibers in textiles is crucial for ensuring the quality of yarns and fabrics made from animal hair. Among others, Fourier transform infrared (FT-IR) spectroscopy is a technique that identifies vibrations associated with chemical bonds, including those found in amino acid groups. Cashmere, mohair, yak, camel, alpaca, vicuña, llama, and sheep hair fibers were analyzed via attenuated total reflection FT-IR (ATR FT-IR) spectroscopy and scanning electron microscopy techniques aiming at the discrimination among them to identify possible commercial frauds. ATR FT-IR, being a novel approach, was coupled with chemometric tools (partial least squares discriminant analysis, PLS-DA), building classification/prediction models, which were cross-validated. PLS-DA models provided an excellent differentiation among animal hair of both camelids and eight animal species. In addition, the combination of ATR FT-IR and PLS-DA was used to discriminate the cashmere hair from different origins (Afghanistan, Australia, China, Iran, and Mongolia). The model showed very good discrimination ability (accuracy 87%), with variance expression of 94.88% and mean squared error of cross-validation of 0.1525.

Study of the effect of N, N-diethyl hydroxyl amine/multi-layered graphene oxide hybrid on reducing cathodic delamination and increasing corrosion resistance of epoxy coating on steel substrate

In this study, a hybrid of multi-layered graphene oxide (MLGO) and oxygen absorbent corrosion inhibitor N, N-diethyl hydroxylamine (DEHA) was investigated. The nano hybrid was prepared in order to reduce the amount of cathodic delamination and increase the corrosion resistance of the epoxy coating. Epoxy coatings were prepared using the optimal percentage of 0.75 wt. % of the nano hybrid with different ratios between MLGO and DEHA like (1:2), (1:1) and (2:1). Mapping energy-dispersive X-ray spectroscopy, thermo gravimetry analysis and Fourier transform infrared (FT-IR) analysis indicated the uniform distribution of the inhibitor throughout the MLGO structure and the hydrogen bond interactions between them. The results of FT-IR spectroscopy: attenuated total reflectance test after six months confirmed the presence and stability of the inhibitor in the coating. Also, the results of 800 h of salt spray test and the long-term electrochemical impedance test after 7 months showed that the epoxy coating, containing MLGO-DEHA (1:2) had the highest corrosion resistance (2.54 × 107 Ω cm2) and the lowest cathodic delamination (15.9%). The results were also confirmed by cathodic delamination and pull-off adhesion tests.

The Influence of Temperature and Stoichiometry on the Optical Properties of CdSe Nanoplatelets

Colloidal quasi-two-dimensional cadmium chalcogenide nanoplatelets have attracted considerable interest due to their narrow excitonic emission and absorption bands, making them promising candidates for advanced optical applications. In this study, the synthesis of quasi-two-dimensional CdSe NPLs with a thickness of 3.5 monolayers was investigated to understand the effects of synthesis temperature on their stoichiometry, morphology, and optical properties. The NPLs were synthesized using a colloidal method with temperatures ranging from 170 °C to 210 °C and optimized precursor ratios. Total reflection X-ray fluorescence (TXRF) analysis was employed to determine stoichiometry, while high-resolution transmission electron microscopy (HRTEM) and UV-Vis spectroscopy and photoluminescence spectroscopy were used to analyze the structural and optical characteristics. The results showed a strong correlation between increasing synthesis temperature and the enlargement of nanoscroll diameters, indicating dynamic growth. The best results in terms of uniformity, stoichiometry, and optical properties were achieved at a growth temperature of 200 °C. At this temperature, no additional optical bands associated with secondary populations or hetero-confinement were observed, indicating the high purity of the sample. Samples synthesized at lower temperatures exhibited deviations in stoichiometry and optical performance, suggesting the presence of residual organic compounds.

Combining microscale ATR-FTIR and chemometrics to interpret degradation characteristics of earlywood, latewood, and compression wood in waterlogged archaeological pine wood

Interpreting the degradation characteristics of waterlogged archaeological wood (WAW) is crucial for the conservation of wooden cultural heritage. Generally, multidisciplinary diagnostic methods, including physical, micromorphological, and chemical approaches, are employed to evaluate the preservation state of WAW. However, primarily focused on the sample level, this methodology limits the understanding of the variability in degradation from a detailed perspective. In this paper, we adopted the in-situ microscale attenuated total reflectance Fourier transform infrared (ATR-FTIR) method to investigate the degradation variability in waterlogged archaeological Masson pine (Pinus massoniana) wood excavated from the ancient Chinese shipwreck Nanhai No. 1. Specifically, spectra of earlywood (EW), latewood (LW), and compression wood (CW) were extracted and combined with chemometrics to achieve rapid classification of their degradation levels. The micromorphological features of wood cell walls in conjunction with the ratios of lignin (A1509) and carbohydrate (A1370) peak areas were used to estimate the degradation levels. Unlike recent wood, moderate degradation in CW and severe degradation in EW and LW were classified in archaeological samples. The degradation levels were effectively determined through principal component analysis (PCA) and sparse partial least squares discriminant analysis (sPLSDA). The results suggest that chemometric analysis is a promising method to discern the variable degradation levels of archaeological wood at the tissue level. The methodologies developed in this study provide detailed insights into the degradation characteristics in WAW and improve the accuracy of evaluating the preservation state.

Probing Single-Molecule Dynamics in Self-Assembling Viral Nucleocapsids.

All viruses on Earth rely on host cell machinery for replication, a process that involves a complex self-assembly mechanism. Our aim here is to scrutinize in real time the growth of icosahedral viral nucleocapsids with single-molecule precision. Using total internal reflection fluorescence microscopy, we probed the binding and unbinding dynamics of fluorescently labeled capsid subunits on hundreds of immobilized viral RNA molecules simultaneously at each time point. A step-detection algorithm combined with statistical analysis allowed us to estimate microscopic quantities such as the equilibrium binding rate and mean residence time, which are otherwise inaccessible through traditional ensemble-averaging techniques. Additionally, we could estimate a set of rate constants modeling the growth kinetics from nonequilibrium measurements, and we observed an acceleration in growth caused by the electrostatic screening effect of monovalent salts. Single-molecule fluorescence imaging will be crucial for elucidating virus self-assembly at the molecular level, particularly in crowded, cell-like environments.

Clickable HaloTag ligands for live cell labeling and imaging

Self-labeling protein (SLP) tags, such as HaloTag, have gained considerable interest as advanced tools for live cell labeling. However, the chloroalkane-based substrates that can be directly used for protein labeling are limited. Here, we report two bioorthogonal small molecule linkers, chloroalkane-tetrazine (CA-Tz) and chloroalkane-azide (CA-N3), which can penetrate cell membranes and facilitate click chemistry-based labeling in live cells. We compare their labeling capability using two clickable silicon rhodamine dyes (SiR-PEG3-TCO and SiR-PEG4-DBCO). Confocal imaging results demonstrate that using CA-Tz and SiR-PEG3-TCO dye exhibits superior intracellular labeling with low nonspecific signals. We subsequently compared the photostability of SiR dyes with that of green fluorescent proteins (mEmerald). Total internal reflection fluorescence (TIRF) imaging indicates that SiR dyes exhibit superior photostability under identical excitation conditions, making them suitable for long-term cell imaging. Furthermore, SiR dyes labeling also shows high structure retention for the fourth-order super-resolution optical fluctuation imaging (SOFI) compared to fluorescent proteins. This study presents clickable HaloTag linkers as effective tools for live cell labeling and imaging, highlighting the high-quality labeling of chloroalkane linkers and clickable dyes for live cell imaging.

Poly(ionic) Liquid-Enhanced Ion Dynamics in Cellulose-Derived Gel Polymer Electrolytes.

Gel polymer electrolytes (GPEs) are regarded as a promising alternative to conventional electrolytes, combining the advantages of solid and liquid electrolytes. Leveraging the abundance and eco-friendliness of cellulose-based materials, GPEs were produced using methyl cellulose and incorporating various doping agents, either an ionic liquid (1-Butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide [Pyr14][TFSI]), its polymeric ionic liquid analogue (Poly(diallyldimethylammonium bis(trifluoromethylsulfonyl)imide) [PDADMA][TFSI]), or an anionically charged backbone polymeric ionic liquid (lithium poly[(4-styrenesulfonyl)(trifluoromethyl(S-trifluoromethylsulfonylimino) sulfonyl) imide] LiP[STFSI]). The ion dynamics and molecular interactions within the GPEs were thoroughly analyzed using Attenuated Total Reflectance Fourier-Transform Infrared Spectroscopy (ATR-FTIR), Heteronuclear Overhauser Enhancement Spectroscopy (HOESY), and Pulsed-Field Gradient Nuclear Magnetic Resonance Diffusion (PFG-NMR). Li+ transference numbers (tLi+) were successfully calculated. Our study found that by combining slow-diffusing polymeric ionic liquids (PILs) with fast-diffusing lithium salt, we were able to achieve transference numbers comparable to those of liquid electrolytes, especially with the anionic PIL, LiP[STFSI]. This research highlights the influence of the polymer's nature on lithium-ion transport within GPEs. Additionally, micro supercapacitor (MSC) devices assembled with these GPEs exhibited capacitive behavior. These findings suggest that further optimization of GPE composition could significantly improve their performance, thereby positioning them for application in sustainable and efficient energy storage systems.

Heavy metal contamination in soils of industrial estates of Tamil Nadu, India and source identification by magnetic susceptibility.

An increase in erratic industrial activity has been a major contributing factor to the significant contamination in environmental matrices. This study aimed to ascertain the level of heavy metal contamination in soils in major industrial estates of Tamil Nadu as well as the threats to human health and the environment that concomitant with it. This led to the use of the total reflection X-ray fluorescence (TXRF) spectroscopy technique to analyse 31 soil samples. Thus, the mean heavy metal concentrations were found to be in the ascending order: As < Ni < Pb < V < Cu < Zn < Cl < Mn < Sr < Cr < Al < Fe. Pb, Cr, Cu, As, and Zn have been identified as predominantcontaminants in the study area using the conventional pollution indices such as geo-accumulation index (Igeo), contamination factor (CF), and enrichment factor (EF). The magnetic susceptibility measurements indicates that the percentage of frequency dependence of magnetic susceptibility of the studied soil samples varied from 0.88 to 11.15 and that represents the presence of admixture ofsuperparamagnetic (SP) particles in the soil samples. From the results of multivariate statistical analyses, the sources ofidentified heavy metals were classified as anthropogenic sources(Cr, Cu, Pb, As, and Zn),natural sources(V, Mn, Fe, Ni, and Sr ),and intermediate sources (Al and Cl).

Total resonant terahertz absorption enabled by a large-scale adjustable admittance inverse matching in a metal groove with graphene

Abstract We propose a tunable terahertz (THz) perfect absorber based on a metal groove with graphene-loaded dielectric resonator and theoretically study its basic properties. The proposed absorber allows switching between the regimes of perfect absorption at the Fabry-Perot resonance excited near the cut-off frequency of the metal groove and almost total reflection away from the resonance by changing the Fermi energy in graphene. For this purpose, we propose a “bottom up” approach which is based on tuning the admittance of input line (the metal groove in our case) instead of the structure admittance in order to reach the perfect admittance matching condition. We demonstrate that this effect can be realized at arbitrary selected frequency in the entire THz range due to the dispersion of incoming wave in metal groove, which ensures a large-scale tunability of its characteristic admittance. As a result, the total absorption can be realized in the Fabry-Perot resonance even in a simple graphene-loaded dielectric cavity for any admittance of graphene layer, which is advantageous as compared to majority of existing THz absorbers with more complicated design.

Gecko-inspired adhesion enhanced by electroadhesive forces

Abstract Soft robotic manipulators have been increasingly adopted over the last decade due to their passive conformation to the shapes of objects, which can reduce control complexity. The performance of these grippers can be improved using flexible adhesive skins that increase tactile gripping forces, which is particularly important when grasping delicate objects and flexible substrates that are otherwise difficult to manipulate. In this work, we investigate how passive gecko-inspired fibrillar adhesion can be augmented by actively controlled electroadhesion (EA). The passive gecko-inspired outer skin (GS) enables adhesion with no power consumption while EA is controlled with an applied voltage. A numerical finite-element model is used to investigate how EA is affected by a commercially available gecko-inspired skin. The results show that the dielectric properties of the gecko-inspired skin reduce the magnitude of field intensity on the adhesive contact surface by only 2.1% at 3 kV. Compared with GS alone, EA with gecko-inspired skin (EAGS) increases the shear force by 66.8% and the normal force by 53.7% with an applied voltage of 4 kV. It is shown that the gecko skin’s adhesion force is enhanced by increased engagement of the fibrillar microstructure to object surfaces due to EA. This is experimentally demonstrated using frustrated total internal reflection imaging. This work shows that electroadhesive-enhanced gecko-inspired skin generates a greater adhesive force than the sum of forces from the separate gecko-inspired skin and EA. In this way, electrically controllable and passive adhesion mechanisms can be combined to improve the handling of flexible and delicate objects with smooth or rough surfaces.&amp;#xD;

Levels and Classification of Microplastics and Their Impact on the Wellbeing of Selected Commercially Important Fish Species in Kisumu Bay, Lake Victoria.

Microplastics (MPs) are emerging pollutants of concern in aquatic ecosystems. Fish ingest MPs accidentally during normal feeding because they resemble prey or by ingesting prey that previously consumed them. Despite severe plastic pollution in Africa, some countries, including Kenya have implemented laws to curb this pollution menace. MPs have scantly been studied in African freshwaters. This study provides empirical data and describes the levels of MPs in four commercially important fish species in Lake Victoria. A total of 95 fish samples were collected from four sampling sites (inshore-offshore waters) between March and May 2022. Microscopy and Attenuated Total Reflectance Fourier Transformed Infrared (ATR-FTIR) spectroscopy methods were used to identify MPs. In this study, 62 out of 95 (65.26%) of the gastrointestinal tracts of the sampled fish contained MPs. The four species showed different proportions of detected MPs among the sampled individuals: 75.00% (Clarias gariepinus), 75.00% (Synodontis victoriae), 71.43% (Lates niloticus), and 59.26% (Oreochromis niloticus). Polystyrene (PS) and poly (perfluorobutadiene) were the main plastic polymers in the fish samples. The condition factors estimated for O. niloticus, S. victoriae, and L. niloticus were > 1 and < 1 for C. gariepinus, respectively. Positive correlations were observed between microplastic numbers and fish length and microplastic numbers and fish weight. However, the low R2 values obtained implied no strong relationship exists between these parameters. These findings provide evidence of microplastic contamination in fish in Kisumu Bay.

Hydrophobic deep eutectic solvent-ferrofluid microextraction followed by liquid chromatography-mass spectrometry for the enantioselective determination of chiral agrochemicals in natural waters.

The increasing use of chiral agrochemicals sold as racemic formulations raises concern for the negative impacts that inactive enantiomers can have on aquatic life and human health. The present work just focuses on the determination of ten chiral pesticides in river water samples by applying a ferrofluid-based microextraction followed by their stereoselective liquid chromatography analysis. To develop the ferrofluid, magnetite nanoparticles were prepared and coated with oleic acid and then dispersed in a hydrophobic natural deep eutectic solvent (NaDES), composed ofL-menthol and thymol (1:1). The stable colloidal dispersion was characterised by scanning electron microscopy, thermogravimetric analysis, energy-dispersive X-ray spectroscopy and attenuated total reflection Fourier transform infrared spectroscopy. The analyte microextraction from 5ml river samples was performed using 50µl of ferrofluid, while acidified acetonitrile (150µl) was used to break down the ferrofluid and solubilise the NaDES containing the analytes. All the extracts were analysed by high-performance liquid chromatography-tandem mass spectrometry. For each analyte, the baseline separation of isomers was achieved on a Lux i-Amylose-3 column (amylose tris(3-chloro-5-methylphenylcarbamate) working in reversed-phase mode; the combination with mass spectrometry detection allows the overall separation of 24 isomers (ten chiral analytes among which eight containing a single (one) chiral centre, one with two chiral centres and the last one existing in four stereoisomeric forms, due to the presence of two regioisomers with a chiral carbon) within 37min. The method showed very good figures of merit in terms of recoveries (77.7-97.5%), intra-day and inter-day precision (2.7-7.7% and 6.9-14.9%, respectively), limit of detection (0.01-0.35µg/L), limit of quantitation (0.03-1.20µg/L), linear dynamic range, and intra-day and inter-day accuracy (1.2-14.8% and 1.8-15.0%, respectively). The presented method was able to detect 14 out of 24 isomers at the preventive limit established by the Italian legislation for single pesticide (that for a chiral pesticide is the sum of all its isomers) in surface waters, set at 0.1µg/l. Finally, the method was evaluated using AGREEprep and ComplexGAPI metrics, compared with other ferrofluid-based methods, and applied to the analysis of water samples from two Italian rivers (the Nera River and the Tiber River), providing to be sustainable and reliable for the application to real river matrices.

Infrared biospectroscopy as a rapid screening tool for COVID-19 diagnosis

BackgroundAdvanced screening technologies, particularly biospectroscopic techniques like infrared attenuated total reflection (IR-ATR) spectroscopy, are gaining significance for their potential to offer fast, reliable, and specific diagnostic methods. These techniques, combined with chemometric approaches, have been increasingly applied for identifying bacterial and viral infections, cancer screening, and are now reported as useful in the context of COVID-19 and Long-COVID. The application IR-ATR, in point-of-care settings is crucial across various contexts. The ongoing progress in deploying IR-ATR in clinical settings represents a significant advancement in infectious disease screening.ObjectiveThe main objective of this study is to demonstrate the efficacy of IR-ATR as a rapid, sensitive, and specific tool for pathogen detection and infection monitoring at the clinical level, in agreement with existing literature.MethodsThe present study applied IR-ATR spectroscopy as a direct screening methodology that discriminates between patients infected with the SARS-CoV-2 virus and healthy subjects via dried serum samples.ResultsThe chemometric analysis through PCA presented an accuracy of 99.18% with a sensitivity and specificity of 98.83% and 97.32% respectively.ConclusionsThis approach supports the potential of IR-ATR for pathogen detection -SARS-CoV-2- in clinical settings as a rapid, sensitive, specific and minimally invasive technique that could be valuable for the deployment of rapid platforms for pathogen identification and viral infection monitoring.

Exploring Asymmetric Lens–Total Internal Reflection (AL–TIR) Optics for Uniform Ceiling Illumination in Interior Lighting

This study presents a significant advancement in LED interior lighting through the development and application of Asymmetric Lens–Total Internal Reflection (AL–TIR) optics, with a focus on enhancing lighting uniformity and indoor comfort by simulating sky-like lighting distribution. AL–TIR technology employs asymmetric lenses combined with total internal reflection to efficiently redirect and spread light, achieving a controlled and even ceiling illumination suitable for various interior applications. This research explored the establishment of ideal luminous intensity curves, devised practical AL–TIR optical designs through numerical calculations, and conducted extensive simulations to assess performance in typical indoor environments. Our findings demonstrated substantial improvements in lighting uniformity, with the AL and AL–TIR systems achieving direct illuminance uniformities of 0.78 and 0.83, respectively, compared to traditional tube LEDs at 0.25. These results, validated in several office rooms, highlight the efficacy of AL–TIR optics in revolutionizing indoor lighting design by balancing optimal lighting distribution with occupant comfort and well-being.

Dual-Wide Multi-Band (DWMB) four-port flexible MIMO antenna for on-body multiple wireless applications including high diversity performance.

The single-input-single-output technology experiences loss of data in the communication channel due to the receiving antenna undergoing fading of the signal impinged on it. Today's need is faster data transfer with multiple applications in the single antenna with multiple-identical radiating elements, leading to multiple-input-multiple-outputDWMB (MIMODWMB) technology. The MIMODWMB configuration with multi-band capability is the objective of the proposed work with applications ranging between microwave-millimeterWave bands. The four-port Dual-Wide Multi-Band (DWMB) MIMODWMB antenna radiating electro-magnetic-energy is proposed, which generates measured bandwidths of 7.27GHz-34.32GHz (Band 1) and 46.54GHz-71.52GHz (Band 2) including applications Up-link/Down-link Satellite System, X-Band, Ku-Band, ISM 24.0GHz (24.0GHz-24.25GHz), 24.0GHz UWB Band (21.65GHz-26.65GHz), n258, n257/n261 and n263 V-band. The proposed antenna technology is printed on Rogers's low permittivity substrate with a hexagon patch etched with dual merged-elliptical slot and three identical circular slots to achieve high impedance matching for Band 1. The partial-ground is etched by a rectangular slot for better impedance matching, and two-thin-etched rectangular slits generate 60.0GHz Band 2. The thin substrate, thickness 0.254mm, is utilized for flexible applications without compromising the operation of dual wide bandwidths. The flexible antenna is also subjected to analysis of Specific-Absorption-Rate (SAR) analysis at key frequencies within both the bands and found to be within the standard limit of 1.60W/Kg for 1g of the human tissue model and corresponds to 1.01W/Kg at 10.0GHz, 0.280W/Kg at 15.0GHz, 0.475W/Kg at 26.0GHz, 0.588W/Kg at 28.0GHz & 0.301W/Kg at 60.0GHz. The high diversity performance with Envelope Correlation Coefficient<0.50, Diversity Gain≈10.0dB, Total Active Reflection Coefficent<0dB, Channel Capacity Loss<0.40b/s/Hz and multi-band capability for mobile users make the proposed work suitable for flexible on-body applications in a wireless environment. The proposed work MIMODWMB antenna offers advantages such as reduced size (20mm×24mm: 0.61λ0×0.74λ0 at λ0 = 7.27GHz) and a wide range of impedance bandwidths, which are useful for several applications. Also, due to the flexible nature of the design, they can be used for future on-body wearable applications.

Materials and Techniques of the Mural Paintings in the Church-Ossuary of the Rila Monastery, Bulgaria

This presented research examined the wall paintings in the Church-Ossuary Presentation of the Blessed Virgin, part of the most important Rila Monastery complex in Bulgaria, painted by the painters from Mount Athos in 1795. The painting materials used to create the unique murals were studied for the first time by optical microscopy (OM), attenuated total reflectance Fourier transform infrared (ATR–FTIR), scanning electron microscopy energy dispersive X-ray spectroscopy (SEM–EDS), and enzyme-linked immunosorbent assay (ELISA). The vibrational and elemental analysis showed that the color palette of the paintings is composed of pigments traditional for Orthodox church wall paintings such as natural pigments, including yellow ochre, red ochre, green earth, and calcite, as well as other historical pigments of synthetic origin, including smalt, red lead, cinnabar, and verdigris. The analysis of the binders by the ATR–FTIR spectroscopy and enzyme-linked immunosorbent assay (ELISA) analysis implied the use of the post-Byzantine egg tempera technique. Only the blue backgrounds in the murals were painted using a smalt-based paint mixed with a carbohydrate binder. Based on the current analysis and comparison with the successive paintings in the other churches of the Rila Monastery, it could be concluded that the technology of the painting process followed by the Athonite artists during the work in the Church-Ossuary became a point of reference for many Bulgarian icon-painters later.

A Blockchain based Secure Authentication Technique for Ensuring User Privacy in Edge Based Smart City Networks

In the past decade, modernization of Information and Communication Technology (ICT), Edge Computing (EC), and Smart Cities has attracted significant academic interest due to its diverse applications in the fields of healthcare, transportation, agriculture, and defense. EC offers numerous advantages, including faster and more efficient services, lower latency, improved data processing, managed bandwidth consumption, scalable, real-time decision-making, security, reduced network congestion, and increased resilience. Despite these benefits, EC networks face persistent challenges, particularly related to security and privacy concerns. Addressing these security challenges requires strong authentication mechanisms, which demand extra resources like processing power and memory, often surpassing the limited capabilities of lightweight edge devices compared to cloud systems. This highlights the critical need for securing edge nodes and ensuring user privacy before real-world deployment and data transfer. User and edge device authentication is vital to prevent external and internal Impersonation and Reflection attacks that threaten system integrity and confidentiality. This paper presents a BlockChain based Authentication technique for Edge Networks (BCAuthEN) that utilizes a Consortium Blockchain (CB) with key agreements for biometric authentication, incorporating a Fuzzy Extractor (FE) to secure user biometrics and passwords. In addition, BCAuthEN offers multifactor and continuous authentication by monitoring user behavior and biometrics. BCAuthEN has been formally verified through Real-Or-Random (RoR) modeling and AVISPA tool, proving its effectiveness in enhancing privacy, and security. The proposed technique ensures robust security by preventing attackers at the potential entry points (edge nodes). In addition, BCAuthEN reduces computation cost, communication overhead and improves throughput. BCAuthEN provides strong resilience by achieving high detection accuracy and reduces false positives against impersonation and reflection attacks. Results have shown that BCAuthEN improves communication costs and reduces overhead by 10% and 7%, respectively, as compared to the recent biometric and key-based user authentication techniques.

Enhanced photocatalytic hydrogen evolution via yolk–heteroshell TiO2@TiO2/SiO2 nanoreactor with confined Pt nanoparticles

The upper limit of photocatalytic efficiency is largely determined by the light-harvesting capability of a semiconductor. To address this challenge, we developed a yolk-heteroshell TiO2@TiO2/SiO2 (T@T/S) nanoreactor, leveraging a novel design based on an in-depth understanding and innovative utilization of light-matter interactions. The T@T/S nanoreactor significantly enhances solar light capture and utilization efficiency through total internal reflection mechanisms facilitated by the heterogeneous shell. This heteroshell, consisting of an outer SiO2 shell an inner monolayer of TiO2 nanoparticles, maximizes light confinement due to the different refractive indices of SiO2 and TiO2, while also minimizing mass transfer resistance due to the thin inner shell layer. These unique structural features result in high photocatalytic activity under simulated solar light. Additionally, we successfully applied a “ship-in-a-bottle” strategy for the confined growth of platinum nanoparticles within T@T/S nanoreactor. The Pt0.5-T@T/S nanoreactors demonstrated excellent hydrogen production, achieving a hydrogen evolution rate of 24.43 mmol g−1h−1 under simulated sunlight and an apparent quantum efficiency (AQE) of 7.8 % at 350 nm. This study highlights the importance of nano-engineered designs in optimizing semiconductor photocatalysts and shows the significant potential of our approach for sustainable energy conversion and environmental protection.

Development of FTIR-ATR Spectra and PLS Regression Combination Model for Discrimination of Pure and Adulterated Acacia Honey

A Fourier Transform Infrared Spectroscopy and attenuated total reflectance (FTIR-ATR)-based chemometric model was evaluated for the rapid identification and estimation of adulterants in honey. Two types of honey, bee honey and stingless bee honey, were adulterated with acid adulterants (acetic acid, citric acid, and tamarind extract) at different concentrations of 1%, 3%, 5%, and 7% and sugar adulterants (liquid corn syrup, cane sugar, palm sugar, and inverted sugar) at different concentrations of 1%, 2%, and 3%. The physicochemical properties (Brix, moisture content, pH, and free acidity) and sugar contents (glucose, fructose, and sucrose) of each type of honey and their adulterated samples were determined before FTIR analysis. For all the samples, FTIR spectra were acquired in the mid-infrared range (400-3600 cm-1) and the spectra obtained were subjected to partial least squares (PLS) analysis to develop the model for the determination of adulterants in honey samples. The PLS model produced high coefficient of determination (R2) for bee honey adulterated with acetic acid (0.95), citric acid (0.98), tamarind extract (0.97), and stingless bee honey adulterated with liquid corn syrup (0.99), inverted sugar (0.91), cane sugar (0.86), and palm sugar (0.77). A recognition model was developed for mixture detection and verified through the physicochemical analysis. The combination of FTIR-ATR spectra and the PLS regression model can be a fast, reliable, nondestructive method to detect honey adulteration.