Total Reflection Research Articles

Ab initio analytical model of lasing in plasmonic lattices

The first-principles theory of lasing in a rectangular lattice of spherical metal nanoparticles is developed in a fully analytical form in the dipole approximation. The lasing conditions are obtained for different diffraction orders, both propagating and evanescent. Their analysis reveals that, in addition to typical lasing, there can be lasing without population inversion, which is invisible in conventional experiments, but can be observed in total internal reflection.

Radiopaque hydrogel-in-liposomes towards theranostic applications for malignant tumors.

A radiopaque hydrogel-in-liposome (RHL) system was developed for micro-computed tomography (μCT) imaging of tumor tissue and simultaneous delivery of a cytotoxic agent. Iopamidol (IPD) and doxorubicin (DOX) were incorporated as the CT contrast and anti-cancer agents, respectively. The presence of a polyethylene glycol hydrogel core in the liposomes was confirmed via attenuated total reflectance Fourier transform infrared, proton nuclear magnetic resonance, and selective solvent extraction. Nano-sized (∼160 nm) spherical DOX/IPD-loaded RHLs with a narrow size distribution and negative zeta potential were successfully fabricated. The RHLs demonstrated enhanced cellular uptake of DOX in SCCVII cells compared to conventional radiopaque liposomes, likely due to clathrin-mediated endocytosis. Additionally, pH-dependent DOX release and reduced IPD leakage were observed. In vivo studies using SCCVII tumor-xenografted mice showed that RHLs exhibited improved CT contrast efficiency and anti-tumor efficacy, along with systemic biocompatibility, attributed to enhanced tumor-targeting properties. These findings suggest that the RHL system could serve as a promising nano-platform for tumor theranostics.

Beneath and beyond frustrated total reflection: A practical demonstration

Beneath and beyond frustrated total reflection: A practical demonstration

Synergistic Catalysis in Fe─In Diatomic Sites Anchored on Nitrogen-Doped Carbon for Enhanced CO2 Electroreduction.

Diatomic catalysts are promising for the electrochemical CO2 reduction reaction (CO2RR) due to their maximum atom utilization and the presence of multiple active sites. However, the atomic-scale design of diatomic catalysts and the elucidation of synergistic catalytic mechanisms between multiple active centers remain challenging. In this study, heteronuclear Fe─In diatomic sites anchored on nitrogen-doped carbon (FeIn DA/NC) are constructed. The FeIn DA/NC electrocatalyst achieves a CO Faradaic efficiency exceeding 90% across a wide range of applied potentials from -0.4 to -0.7V, with a peak efficiency of 99.1% at -0.5V versus the reversible hydrogen electrode. In situ, attenuated total reflection surface-enhanced infrared absorption spectroscopy and density functional theory calculations reveal that the synergistic interaction between Fe and In diatomic sites induce an asymmetric charge distribution, which promote the adsorption of CO2 at the Fe site and lowered the energy barrier for the formation of *COOH. Moreover, the unique Fe─In diatomic site structure increase the adsorption energy of *OH through a bridging interaction, which decrease the energy barrier for water dissociation and further promoted CO2RR activity.

Discriminatory power of trabeculectomy bleb internal reflectivity and morphology in surgical success using anterior segment optical coherence tomography

BackgroundThe post-operative evaluation of trabeculectomy blebs has traditionally relied on subjective clinical grading systems performed at the slit-lamp. This study explores the use of swept source anterior-segment optical coherence tomography (AS-OCT) to objectively measure bleb internal reflectivity and morphology, and to distinguish blebs with surgical success vs. failure.MethodsCross-sectional study of patients with glaucoma who had undergone trabeculectomy at least one year prior. Swept source AS-OCT was used to capture filtering blebs in the sagittal plane. Standardised regions of interests on the sagittal plane were segmented, and pixel intensity values and bleb height were measured. Receiver operating characteristic curves were used to examine the discriminatory ability of pixel intensity values and bleb morphology to classify blebs with surgical success or failure.Results100 eyes of 65 patients were included, with a median post-operative follow up of 7.0 years (IQR 3.2–16 years). The proportion of complete success, qualified success and failure was 45%, 33%, and 22% respectively. The maximum bleb height was significantly greater in the blebs with complete success (1.74 vs. 1.25 vs. 1.23 mm in CS vs. QS vs. F, one-way ANOVA, p < 0.0001). Mean pixel intensity was significantly lower in blebs with complete success (150.8 vs. 157.4 vs. 167.4 in CS vs. QS vs. F, p = 0.0001). Bleb intensity standard deviation (AUC 0.81), maximal bleb height (AUC 0.76), mean pixel intensity (AUC 0.75) and minimum pixel intensity (AUC 0.75) offered the best discrimination between surgical success and failure.ConclusionsSwept-source AS-OCT can be used to quantify bleb internal reflectivity and morphology, which can be used to distinguish between well vs. poorly functioning blebs. These parameters may assist surgeons in the objective evaluation of post-operative bleb outcomes.

Synthetic Receptors Decorated on Nanoparticles for Selective and Sensitive Glyphosate Detection

Herein, an innovative glyphosate imprinted poly(hydroxyethyl methacrylate-N-methacroyl-(L)-phenylalanine methyl ester nanoparticles (MIP@NPs) based plasmonic nanosensor featured with high sensitivity and selectivity was constructed by using the molecular imprinting technique and used for real-time glyphosate detection. The characterization of nanoparticles was performed by the nano Zetasizer and scanning electron microscopy (SEM), while nanosensors were characterized by the Fourier transform infrared-attenuated total reflection (FTIR-ATR) and contact angle measurement. Control experiments were conducted to evaluate the imprinting efficiency on the signal response using a non-imprinted surface plasmon resonance (NIP SPR) nanosensor prepared without adding glyphosate pesticide into the polymerization mixture. The MIP@NPs integrated molecularly imprinted surface plasmon resonance (MIP SPR) nanosensor having synthetic molecular recognition elements yielded a novel biosensing platform for label-free detection and real-time monitoring of glyphosate pesticide. The MIP SPR nanosensor detected the target glyphosate molecule 4.950 times more selectively than the competitor molecule malathion while 3.918 times more selectively than the competitor molecule malaoxon. In addition, the imprinting efficiency factor was found to be 6.76, indicating that the molecular imprinting process was successful. In addition, the imprinting factor was found to be 6.76. Kinetic studies and adsorption characteristics of glycosate adsorption were carried out to assess adsorption dynamics. The linear concentration range for glyphosate detection was 0.001 ppm–10.000 ppm of pesticide, and the detection limit was found to be 0.120 ppb. Studies on the repeatability of the MIP SPR nanosensor revealed that even after five cycles, the signal response for glyphosate detection did not change significantly with relative standard deviation, RSD<1.5 value. The artificial urine selected as the real sample was spiked with glyphosate at a final concentration of 10.000 ppm to evaluate the matrix effect, and the glyphosate amount was reported.

Topical delivery performance of Pickering emulsions stabilized by differently charged spirulina protein isolate/Chitosan composite particles.

Pickering emulsions, stabilized by particulate particles, have emerged as a promising vehicle for topical delivery. Herein, Pickering emulsions stabilized by differently charged spirulina protein isolate - chitosan (SC) composite particles were studied for effective topical delivery of α-Bisabolol (ABS). The composite particles were synthesized via electrostatic assembly of spirulina protein isolate (SPI) and chitosan (CS), and their surface charge was assessed using zeta potential measurements. The Pickering emulsions stabilized by SC composite particles with different charges were all stable over 30 days and had a high encapsulation efficiency for ABS. In vitro skin permeation study revealed that positively charged emulsions significantly increased ABS retention within the skin, predominantly in the stratum corneum layer. The underlying delivery mechanism was further explored using attenuated total reflection Fourier transform infrared spectroscopy. Lastly, the influence of particle concentration and oil phase volume fraction on the topical delivery efficiency was conducted to optimize the Pickering formulations. This study provides insight into the role of particle charge in enhancing topical delivery of Pickering emulsions.

Use of Fourier transform infrared spectroscopy and chemometric analysis to predict the bacilloscopic index in the saliva of leprosy patients.

Leprosy is an infectious disease caused by the Mycobacterium leprae complex. Although the diagnosis of this disease is clinical, additional tests are often needed. One of the most common tests is intradermal smear bacilloscopy, which detects the patient's bacillary load. However, bacilloscopy is an invasive test and its results are subjective. The aim of this study was to propose a methodology based on Fourier transform infrared (FTIR) spectroscopy to predict the bacilloscopic index in the saliva of leprosy patients. A total of 88 saliva samples were included, and the bacilloscopic index of the patients was previously defined by intradermal smear bacilloscopy. The saliva samples were analyzed by attenuated total reflection (ATR)-FTIR; a supervised analysis with partial least squares regression (PLS), after orthogonal signal correction (OSC), was used to predict the bacilloscopic index. The PLS model with three latent variables and one OSC component obtained a coefficient of determination greater than 0.9999 in both the calibration and prediction sets. The model was able to predict the bacilloscopic indexes with a minimum error, demonstrating its robustness. Thus, modeling with ATR/FTIR and multivariate calibration using one OSC component showed high accuracy and reproducibility, overcoming the limitations of intradermal smear bacilloscopy and proving to be a promising method in the clinical management of patients with leprosy.

A Compact Octa Port MIMO Antenna Using Shared Radiator RDRA Array for Applications in ITS

This article details a compact octa-port Multi-Input-Multi-Output (MIMO) antenna tailored for Intelligent Transportation System (ITS) applications. The process begins with crafting a shared radiator-based two-element array for dual-port MIMO functionality, employing orthogonal feeding to ensure high isolation – a critical factor for optimal performance. The apex of our design efforts results in an octa-port MIMO antenna, built upon the foundation element, the dual-port MIMO system with shared radiators. This system is meticulously engineered to attain maximum isolation between its ports. Under worst-case conditions during orthogonal mode excitation, isolation measures at −18 dB, while in other cases, isolation exceeds −20 dB. Impedance bandwidths of 5.5%, 4.13%, 5.1%, and 4% are attained for Port1, Port2, Port3, and Port4, respectively (only four ports are given due to symmetry). The article delves extensively into various MIMO performance metrics, encompassing the total active reflection coefficient (TARC), diversity gain (DG), channel capacity loss (CCL), and envelope correlation coefficient (ECC). Crucially, the measured performance consistently falls within acceptable thresholds, confirming the suitability of this specified MIMO antenna for intelligent automotive applications, especially within the realm of Intelligent Transportation Systems (ITS).

Assessing plastic ingestion in the White stork (Ciconia ciconia) through regurgitated pellets.

Pollution is one of the main factors that threaten biodiversity nowadays. Plastic waste is a global problem which impacts not only on the marine environment but also on the terrestrial one. Great amounts of this kind of refuse are compiled in landfills, where lots of avian species feed. In contrast to seabirds research, there are limited studies that have considered how plastic is being ingested by land birds even when they are being affected both physically and at an endocrine level. We tried to assess the number of plastics and microplastics ingested by individuals of a White stork (Ciconia ciconia) colony in central Spain by collecting regurgitated pellets. The chemical composition of the elements was determined, as well as the relation between the amount of ingested plastic by individuals and their use of a landfill. Our results show that 3.44% of the pellet was formed by plastic (n = 50). Polyethylene, polystyrene, polypropylene and PET were the most abundant polymers, all of them being potentially problematic to the organism according to the literature. Each polymer was identified by Fourier transform infrared attenuated total reflectance spectroscopy (FTIR-ATR). We observed that the total amount of ingested plastics was stable along the use of the landfill, meaning White storks obtained plastic not only from anthropogenic sources but also from natural areas, indicating its high rate of pollution. Our study remarks the importance of addressing plastic ingestion in White storks as well as other terrestrial species, not only to understand the possible damage to the population but also to the whole ecosystem.

Hyperbolic polariton-coupled emission optical microscopy

Abstract A new type of optical microscopy based on hyperbolic polariton-coupled emission (HPCE) is demonstrated. By employing hyperbolic metamaterials as the substrate, we show a nearly 6-fold increase in fluorescence intensity in the HPCE microscope compared to total internal reflection fluorescence (TIRF) on glass substrates. Moreover, we achieve precise, time-dependent control of the fluorescence intensity by modulating the incidence angle with a galvo scanner. This tunability offers extensive potential for applications in super-resolution fluorescence microscopy and high-sensitivity sensing, enabling real-time fluorescence intensity adjustment.

Superradiant phase transition in a large interacting driven atomic ensemble in free space

Atoms strongly interacting with light constitute rich quantum-optical systems with the potential for observing cooperative effects and dissipative nonequilibrium phase transitions. We analyze the conditions under which a driven atomic array, characterized by strong dipole–dipole interactions and a large spatial extent, can undergo a superradiant phase transition, also known as cooperative resonance fluorescence. We find that the array can exhibit completely cooperative decay that conserves the collective pseudospin, resulting in a second-order quantum phase transition, with a key hallmark being an abrupt shift from total light reflection by the atoms to rapidly increasing transmission and significant quantum fluctuations. We compare the results with decay mechanisms that fail to conserve pseudospin, leading to a discontinuous first-order phase transition at a critical finite atom number.

Nanoscale Cellular Traction Force Quantification: CRISPR-Cas12a Supercharged DNA Tension Sensors in Nanoclustered Ligand Patterns.

High-throughput measurement of cellular traction forces at the nanoscale remains a significant challenge in mechanobiology, limiting our understanding of how cells interact with their microenvironment. Here, we present a novel technique for fabricating protein nanopatterns in standard multiwell microplate formats (96/384-wells), enabling the high-throughput quantification of cellular forces using DNA tension gauge tethers (TGTs) amplified by CRISPR-Cas12a. Our method employs sparse colloidal lithography to create nanopatterned surfaces with feature sizes ranging from sub 100 to 800 nm on transparent, planar, and fully PEGylated substrates. These surfaces allow for the orthogonal immobilization of two different proteins or biomolecules using click-chemistry, providing precise spatial control over cellular signaling cues. We demonstrate the robustness and versatility of this platform through imaging techniques, including total internal reflection fluorescence microscopy, confocal laser scanning microscopy, and high-throughput imaging. Applying this technology, we measured the early stage mechanical forces exerted by 3T3 fibroblasts across different nanoscale features, detecting forces ranging from 12 to 56 pN. By integrating the Mechano-Cas12a Assisted Tension Sensor (MCATS) system, we achieved rapid and high-throughput quantification of cellular traction forces, analyzing over 2 million cells within minutes. Our findings reveal that nanoscale clustering of integrin ligands significantly influences the mechanical responses of cells. This platform offers a powerful tool for mechanobiology research, facilitating the study of cellular forces and mechanotransduction pathways in a high-throughput manner compatible with standard cell culture systems.

Synergistic Effect of MgO/ZnO on β‐Phase Crystallization in PVDF: A Comparative Study of Mode of Nanofiller Additions for Piezoelectric Applications

AbstractThis study pioneers the investigation into the critical role of the nanofiller addition method in enhancing β‐phase crystallization in polyvinylidene fluoride (PVDF). Hydrothermally synthesized magnesium oxide (MgO) nanoparticles are combined with zinc oxide (ZnO) in two approaches, yielding optimized electroactive properties. Characterization via Attenuated Total Reflectance Fourier Transformed Infrared Spectroscopy (ATR‐FTIR) and X‐ray Diffraction (XRD) confirmed the improved β‐phase crystallization in P/ZM10 film. The superior sensitivity with fast, linear and precise pattern detection of the optimised polymer composite device ensures its usage as a piezoelectric sensor system. Under the realistic irregular hand‐tapping of 22–23 N force, the fabricated prototype generated an output voltage of 96 V and displayed a maximum power density of 66.69 µW cm−2. A laboratory‐level demonstration of the prototype as a piezoelectric sensor in water filters enables its efficiency and feasibility for real‐time applications.

Experimental study on the simultaneous effect of smart water and clay particles on the stability of asphaltene molecule and emulsion phase

Enhancing oil recovery in sandstone reservoirs, particularly through smart water flooding, is an appealing area of research that has been thoroughly documented. However, few studies have examined the formation of water-in-heavy oil emulsion because of the incompatibility between the injected water-folded ions, clay particles, and heavy fraction in the oil phase. In this study, we investigated the synergistic roles of asphaltene and clay in the smart water flooding process using a novel experimental approach. Our results provide new insights into how the behavior and properties of water in heavy oil emulsions are affected by changes in ion-tuned water in clay-rich sandstone reservoirs. To investigate this, heavy oil was combined with aqueous phases (in the absence and presence of clay) for 20 days at 80 °C. Then, the emulsion phases were centrifuged to separate the oil and brine phases (aged oil and brine). The separated oil phases were analyzed using Interfacial Tension (IFT), oil viscosity measurements, and asphaltene onset point precipitation (AOP) experiments. We observed significant decreases in viscosity and AOP when crude oil was exposed to the aqueous phases containing brine and clay, which was also reflected in the IP-143 results. Additionally, ATR (Attenuated Total Reflection) results and elemental analysis obtained from asphaltenes extracted from the aged oil phase, along with zeta potential measurements of the aged oils, indicated a reduction in the concentration of aliphatic groups as well as in the polar and negative components of the asphaltene molecular structure from the oil phases. Furthermore, the analysis of the simultaneous effects of ion-tuned water and clay on emulsion properties revealed differing impacts on the stability of the emulsion phase. These variations were attributed to the contribution of polar asphaltene components at the interface. These findings could potentially reduce undesirable emulsion damage during heavy oil recovery with ion-tuned water flooding in clay-rich reservoirs.

Comparison of Total Hemispherical Reflectance and Emittance Values Between Metformin Extended-Release Tablets Stored Under Ambient and Stress Conditions

Type 2 diabetes is a serious health problem worldwide. Metformin as the first-line drug in diabetes treatment mainly inhibits glucose production in the liver. Diabetes is often accompanied by other diseases, so patients may take many medications at the same time and have trouble controlling the therapy. This, in turn, may result in medications being stored in different, sometimes random places in the patient’s home where elevated temperatures or long-term exposure to solar radiation are possible. In this study, we aimed to analyze whether the total hemispherical reflectance and emittance values of metformin extended-release tablets would distinguish tablets stored correctly from those stored inconsistently with the manufacturer’s recommendations. Unexpired and expired extended-release tablets containing 750 mg metformin were tested. Unexpired tablets were analyzed in two ways i.e., 15 randomly selected tablets were stored as recommended (day 0), and the 15 next tablets in the blister were stored on a windowsill, where they were exposed to daylight for several hours during the day in mid-spring 2024 for 20 days (day 20). Total hemispherical reflectance (THR) was measured within seven spectral ranges from 335 nm to 2500 nm with a 410-Solar Reflectometer while emittance was analyzed within six spectral infrared ranges from 1500 nm to 21 microns with an ET 100 emissometer. The day 0 tablets showed the highest THR values in five spectral ranges from 400 to 1700 nm compared to expired and day 20 tablets. In the further infrared ranges, from 1.5 to 21 microns, unexpired tablets on day 0 had the lowest reflectance compared to day 20 tablets and expired tablets. This means that a greater amount of IR beam was absorbed by this type of tablet. Therefore, higher emittance was demonstrated by day 0 tablets than by other analyzed tablets. In addition, the emittance values for day 0 tablets decreased with increasing temperature. In conclusion, the storage of metformin extended-release tablets under unfavorable conditions may affect the physical structure of this drug form, which is manifested by changes in the reflectance and directional and hemispherical thermal emittance.

Prolonged Impact of Bisphosphonates and Glucocorticoids on Bone Mechanical Properties

Background: This study aimed at investigating the prolonged effects of glucocorticoids and bisphosphonates on bone. Methods: Six-to-eight-month-old skeletally mature male Sprague Dawley rats were randomized to receive a cancer therapy combination of zoledronic acid (ZA = 0.13 mg/kg) and dexamethasone (DX = 3.8 mg/kg) (treatment group, n = 10) or sterile phosphate buffer saline solution (control group, n = 10). The rats received weekly intraperitoneal injections for 8 weeks, which were stopped 6 weeks before euthanasia. Mineralized bone samples were characterized by three-point bending tests, micro-CT imaging, X-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Bone collagen was assessed using tensile tests on the demineralized bones and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy on mineralized and demineralized bones. Results: The samples in the treatment group showed increased tibial cortical thickness, mineral crystal size, and toughness. Analyses of demineralized tibiae revealed decreased collagen tensile strength in the experimental group. The spectroscopic and TGA/DSC analyses showed that the ZA + DX treatment increased the collagen amide I 1660/1690 cm−1 area ratio and collagen denaturalization temperature, indicating a higher level of collagen cross-linking. Conclusions: Bisphosphonates and glucocorticoids led to prolonged changes in the mechanical properties of bone as a result of increased cortical thickness, increased crystal size, and the deterioration of collagen quality.

Quantification of Argan Oil (Argania spinosa L.) Adulterated with Avocado, Flaxseed, Walnut, and Pumpkin Oils Using Fourier-Transform Infrared Spectroscopy and Advanced Chemometric and Machine Learning Techniques

The increasing trend in the popularity of argan oil (AGO), a multi-beneficial health and cosmetic product, can leave it prone to adulteration. The overall goal of this study was to utilize an attenuated total reflectance Fourier-transform infrared spectroscopic and chemometric methods, including partial least squares (PLS), principal component regression (PCR), and artificial neural network (ANN) for the authentication of AGO in the presence of other oil adulterants, avocado oil (AVO), pumpkin seed oil (PSO), flaxseed oil (FSO), and walnut seed oil (WNO). All three chemometrics methods were able to effectively quantify the FSO adulterant concentration across all statistical models, with the most optimal results in the ANN model as applied in the testing set data (RMSEP = 1.454 %v/v, R2 = 0.821). Comparable results were also obtained for PLS (RMSEP = 1.727 %v/v, R2 = 0.807) and PCR (RMSEP = 1.731 %v/v, R2 = 0.846).

Improving the light extraction efficiency of white-light perovskite light-emitting diodes based on quantum dot nanowires.

This study introduces an innovative strategy to enhance the light extraction efficiency (LEE) of white-light perovskite light-emitting diodes (PeLEDs) by incorporating quantum dot nanowires (QD-NWs) that are prepared by a porous anodic aluminum (PAA) substrate. The QD-NWs were synthesized through a combination of inkjet printing and vacuum deposition based on the PAA substrate which features a unique waveguiding structure that redirects post-color conversion fluorescence along its axis, effectively minimizing energy losses such as reabsorption loss and total internal reflection (TIR) loss. Empirical evidence indicates a significant luminance enhancement of 43.79%, accompanied by an enhancement in current efficiency, for PeLEDs incorporating the QD-NWs. By fine-tuning the structural attributes of the PAA substrate to regulate the size of QD-NWs, this research has successfully developed white-light PeLEDs based on quasi-2D blue perovskite, offering a universal strategy for boosting LEE and propelling the evolution of white-light PeLED technology.

Integrated photonic crystal beam splitters based on thin film lithium niobate.

We propose and demonstrate integrated photonic crystal (PhC) beam splitters based on X-cut thin film lithium niobate (TFLN). Its working principle is based on bandgap guidance and total reflection in the PhC slab. We designed two structures: one features a triangular lattice, while the other exhibits a tetragonal lattice. These structures have compact footprint, with size of 14.857×4.982 and 15.275×5.295 µm2 for triangular and tetragonal lattices, respectively. We fabricate these devices by directly etching the TFLN. The measured insertion losses are 3.482 (triangular lattice) and 2.181 (tetragonal lattice) dB. Our proposed PhC beam splitter provides a novel approach for the realization of compact photonic devices on TFLN.