Total Reflection Research Articles

Electrospun PVP Fibers as Carriers of Ca2+ Ions to Improve the Osteoinductivity of Titanium-Based Dental Implants

Although titanium and its alloys are widely used as dental implants, they cannot induce the formation of new bone around the implant, which is a basis for the functional integrity and long-term stability of implants. This study focused on the functionalization of the titanium/titanium oxide surface as the gold standard for dental implants, with electrospun composite fibers consisting of polyvinylpyrrolidone and Ca2+ ions. Polymer fibers as carriers of Ca2+ ions should gradually dissolve, releasing Ca2+ ions into the environment of the implant when it is immersed in a model electrolyte of artificial saliva. Scanning electron microscopy, energy dispersive X-ray spectroscopy and attenuated total reflectance Fourier transform infrared spectroscopy confirmed the successful formation of a porous network of composite fibers on the titanium/titanium oxide surface. The mechanism of the formation of the composite fibers was investigated in detail by quantum chemical calculations at the density functional theory level based on the simulation of possible molecular interactions between Ca2+ ions, polymer fibers and titanium substrate. During the 7-day immersion of the functionalized titanium in artificial saliva, the processes on the titanium/titanium oxide/composite fibers/artificial saliva interface were monitored by electrochemical impedance spectroscopy. It can be concluded from all the results that the composite fibers formed on titanium have application potential for the development of osteoinductive and thus more biocompatible dental implants.

Fundamentals of Determination of the Biological Tissue Refractive Index by Ellipsoidal Reflector Method

This paper presents the theoretical fundamentals, prerequisites for creation, and peculiarities of modeling a new method for determining the refractive index of biological tissues. The method uses a mirror ellipsoid of revolution as an optical element to ensure total internal reflection phenomena. This paper thoroughly analyzes the differences in the refractive index of healthy and pathological tissues on a biometric diagnostic basis. The analysis is used to model the measurement setup’s parameters. This paper also considers various methods of determining the refractive index of biological tissues based on different principles of physical optics, such as interferometry, refractometry, ellipsometry, and goniophotometry. It systematizes typical optical elements of total internal reflection that can be used in goniophotometry. It justifies the selection of the element base for the goniometric installation based on the ellipsoidal reflector method. A simulation of the installation operation was carried out for various parameters of the ellipsoidal reflector, ensuring the measurement of the biological tissue refractive index from 1.33 to 1.7. This paper also proposes a constructive solution for manufacturing an ellipsoidal reflector of the required configuration.

C2-domain abscisic acid-related proteins regulate the dynamics of a plasma membrane H+-ATPase in response to alkali stress.

Arabidopsis (Arabidopsis thaliana) H+-ATPase1 (AHA1), a plasma membrane (PM)-localized H+-ATPase, plays a key role in plant alkali stress tolerance by pumping protons from the cytoplasm to the apoplast. However, its molecular dynamics are poorly understood. We report that many C2-domain ABA-related (CAR) protein family members interact with AHA1 in Arabidopsis. Single or double mutants of CAR1, CAR6, and CAR10 had no obvious phenotype of alkali stress tolerance, while their triple mutants showed significantly higher tolerance to this stress. The disruption of AHA1 largely compromised the increased alkali stress tolerance of the car1car6car10 mutant, revealing a key role of CARs in AHA1 regulation during the plant's response to a high alkali pH. Furthermore, variable angle total internal reflection fluorescence microscopy was used to observe AHA1-mGFP5 in intact Arabidopsis seedlings, revealing the presence of heterogeneous diffusion coefficients and oligomerization states in the AHA1 spots. In the aha1 complementation lines, alkali stress curtailed the residence time of AHA1 at the PM and increased the diffusion coefficient and particle velocity of AHA1. In contrast, the absence of CAR proteins decreased the restriction of the dynamic behavior of AHA1. Our results suggest that CARs play a negative role in plant alkali stress tolerance by interacting with AHA1 and provide a perspective to investigate the regulatory mechanism of PM H+-ATPase activity at the single-particle level.

Ecofriendly bleaching method for cotton fabric: Development of titanium dioxide doped single wall carbon nanocomposites by photocatalytic treatment for sustainable textile pre-finishing applications

This study aimed to find an eco-friendly substitute method and chemical for conventional hydrogen peroxide (H2O2) bleaching of cotton fabric. We developed diverse functional groups containing titanium dioxide-doped single-wall carbon nanotubes (TiO2-SWCNTs) particles, designed a photocatalytic system, and examined the effects of working conditions and functional group variations on the degree of fabric whitening. Throughout the many phases of the chemical development process, X-ray diffraction (XRD), Fourier transform infrared spectroscopy −Attenuated total reflectance (FTIR-ATR) and the scanning electron microscopy (SEM) tests were conducted. In addition, the color spectrum values, the whiteness indexes, the results of the tearing test, SEM and FTIR-ATR findings of 100% cotton textiles were presented that were treated with TiO2-SWCNTs particles using the photocatalytic technique. The test results demonstrated the successful synthesis of various types of TiO2-SWCNTs, leading to a significant enhancement in the whiteness of the cotton fabrics. This increase reached 21.79% using a small amount of nano-chemicals, surpassing the whiteness index value created by the conventional H2O2 bleaching process. Optimal results were achieved by using minimum quantities of substance and working at moderate temperatures. According to this information, it can be concluded that this approach may serve as a substitute for the conventional H2O2 whitening procedure in terms of both the substance utilized and the application method, specifically for treating cotton fabric. Moreover, the statistical analysis revealed that the fabric’s self-cleaning capacity is significantly influenced by the square of temperature and pH.

β-Cyclodextrin-Modified Cotton Fabric for Medical and Hospital Applications with Photodynamic Antibacterial Activity Using Methylene Blue

The use of cyclodextrins in textiles for the development of biofunctional fabrics represents an interesting alternative for the advancement of dental, medical, and hospital materials. Cyclodextrins can interact with the chemical groups present in cotton fibers, leading to the formation of a nanostructured surface with specific functional properties, including antibacterial activity. Although there are numerous antibacterial textile finishes, the use of methylene blue as a cyclodextrin host molecule for photodynamic applications in textile materials remains to be investigated. This is because methylene blue is a photosensitive dye capable of generating singlet oxygen (1O2) when illuminated, which inactivates the pathogenic microorganisms that may be present in wounds. The objective of this study was to develop a biofunctionalized and photoactivatable cotton fabric with antimicrobial properties for use in the cosmetic or medical industries. The materials obtained were characterized via scanning electron microscopy (SEM), Fourier transform infrared spectroscopy with attenuated total reflection (FTIR-ATR), the determination of cotton fabric functionalization dyeing variables, colorimetry, UV-VIS spectrophotometry, degradation of 9,10-anthracenediyl-bis(methylene)dimalonic acid (ABDA), photodegradation tests, and microbiological analysis. The results showed that the textile was functionalized with β-cyclodextrin, mainly evidenced by the appearance of the band at 1730 cm−1, indicating the formation of the ester group. Thus, when exposed to light, the non-functionalized material showed greater photobleaching, about 60%, compared to the material treated with cyclodextrin. This result was also reflected in the ABDA degradation kinetics, with the treated material showing 592.00% (first phase) and 966.20% (second phase) higher degradation than the untreated sample. Finally, the photodynamic activity was determined based on the antimicrobial properties of the textile, showing a reduction of more than 99% without exposure to light and 100% when exposed to light. It is believed that this study could open avenues for future research and the development of antimicrobial fabrics, as well as demonstrate the efficiency of the treatment with cyclodextrin in relation to photobleaching.

Sapphire optical fiber with (BN/SiBCN)n coating prepared by chemical vapor deposition for high-temperature sensing applications

To enhance the load-bearing capacity of sapphire optical fiber (SOF) in extreme environments, this study prepared SOF/(BN/SiBCN)n by optimizing the nanostructure through increased deposition temperature of BN using alternating chemical vapor deposition. Simulation results indicated an inverse correlation between the leakage loss of SOF/BN/SiBCN and BN thickness; at room temperature, the tendency for coating cracking along the radial direction of SOF/BN/SiBCN is positively correlated with BN thickness, whereas this trend reverses at 1500 °C. Mechanical testing revealed that the tensile strength of SOF/BN/SiBCN is inversely correlated with the tendency for interlayer cracking, aligning with the findings from residual stress simulations; under an air environment at 1500 °C, SOF/(BN/SiBCN)2 exhibited the highest tensile strength, indicating that the layered matrix design effectively mitigates the risk of BN oxidation by creating barrier layers. Optical test demonstrated that the BN coating functions as a total reflection layer to suppress the scattering of optical signals on the sapphire optical fiber surface. In conclusion, the coating design of SOF/(BN/SiBCN)n could meet the material requirements for sapphire optical fiber sensors in extreme environments .

Optical properties of Makrofol under various alpha fluences

The optical properties of Makrofol samples are investigated under various fluences of alpha exposure (2 MeV at , , , , , , and alphas.cm2 alongside the unirradiated ones (pristine). Several analyses, including UV-visible, diffused reflectance spectroscopy (DRS), photoluminescence (PL), Fourier transform infrared/attenuated total reflectance (FTIR-ATR), X-ray photoelectron spectroscopy (XPS) and sessile drop technique, are carried out to reveal the subsequent variations in the optical features of the irradiated polymer foils. The optical transmittance of the irradiated samples notably increases against the pristine ones, while it undergoes a+ plateau over various fluences. Additionally, the scattering events are more prominent in pristine samples over UV (240-400 nm) and IR (900-1040 nm) compared to the irradiated ones. While there are negligible physical alterations on the polymer surface, the photoluminescence emission gradually decreases with increasing alpha fluences in the irradiated samples mainly due to the reduction in the population of the aromatic rings. The latter is also verified by means of the surface chemical analyses such as XPS, FTIR-ATR and sessile drop/contact angle measurements. XPS reveals that the alpha particles give rise to the successive scissions of C-C and C=O bonds and the consequent recombination events in the form of C-O bonds, evidenced by the changes in their abundance percentages. Concurrently, the surface hydrophilicity initially elevates up to a certain fluence and then reduces at higher fluences, indicating a couple of competitive mechanisms are involved in the context of the interactions of the alpha particles with the Makrofol polycarbonate (PC).

Surface Microstructure Study on Corona Discharge-Treated Polyethylene Using Positron Annihilation Spectroscopy

The microstructure and chemical properties of the corona discharge process could provide an effective method for predicting the performance of high-voltage cable insulation materials. In this work, the depth profile of the microstructure and chemical characteristics of corona discharge-treated PE were extensively investigated using Doppler broadening of position annihilation spectroscopy accompanied with positron annihilation lifetime spectroscopy, attenuated total reflectance Fourier transform infrared spectra, Raman spectra and contact angle measurement. By increasing corona discharge duration, the oxygen-containing polar groups, including hydroxyl, carbonyl and ester groups, strongly contribute to the deterioration of hydrophobicity and the enhancement of hydrophilicity. And the mean free volume size, with a broadening distribution, decreases slightly. The line shape S parameter decreases because of the decrease in free volume elements and the appearance of oxygen-containing groups. Also, the thickness of the degradation layer, determined from the S parameter with positron injection depth, increases and diffuses into the PE matrix. A linear S-W plot within the degradation layer of different corona treatment duration samples indicates the defect type does not change. The S parameter decreases and the W parameter increases with an increasing corona duration. Using a slow positron beam, the nondestructive probe can be used to profile the microstructure and chemical environment across the corona discharge damage depth, which is beneficial for investigating the surface and interfacial insulation materials.

Electrochemical CO2 Reduction in Acidic Electrolytes: Spectroscopic Evidence for Local pH Gradients.

Inspired by recent advances in electrochemical CO2 reduction (CO2R) under acidic conditions, herein we leverage in situ spectroscopy to inform the optimization of CO2R at low pH. Using attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) and fluorescent confocal laser scanning microscopy, we investigate the role that alkali cations (M+) play on electrochemical CO2R. This study hence provides important information related to the local electrode surface pH under bulk acidic conditions for CO2R, both in the presence and absence of an organic film layer, at variable [M+]. We show that in an acidic electrolyte, an appropriate current density can enable CO2R in the absence of metal cations. In situ local pH measurements suggest the local [H+] must be sufficiently depleted to promote H2O reduction as the competing reaction with CO2R. Incrementally incorporating [K+] leads to increases in the local pH that promotes CO2R but only at proton consumption rates sufficient to drive the pH up dramatically. Stark tuning measurements and analysis of surface water structure reveal no change in the electric field with [M+] and a desorption of interfacial water, indicating that improved CO2R performance is driven by suppression of H+ mass transport and modification of the interfacial solvation structure. In situ pH measurements confirm increasing local pH, and therefore decreased local [CO2], with [M+], motivating alternate means of modulating proton transport. We show that an organic film formed via in situ electrodeposition of an organic additive provides a means to achieve selective CO2R (FECO2R ∼ 65%) over hydrogen evolution reaction in the presence of strong acid (pH 1) and low cation concentrations (≤0.1 M) at both low and high current densities.

Determining aqueous deuterium detection limits via infrared spectroscopy to understand its capabilities for real-time monitoring of tritiated water

Tritiated water will be present in many demonstrator class fusion devices in a wide array of locations and concentrations. Accurate and fast measurement will be a key requirement to ensure suitable process monitoring, safety assurance and tritium tracking is in place. This work quantifies the deuterium detection limits achievable using a benchtop transmission Fourier transform infrared (FTIR) instrument and an industrialised attenuated total reflectance (ATR)-FTIR instrument to understand the capabilities of these techniques for real-time monitoring of aqueous tritium. Deuterium limits of detection of 4.62 × 10-5 mol mL-1 and 1.07 × 10-3 mol mL-1 were demonstrated with measurement times of 10s for the transmission FTIR and ATR-FTIR, respectively. These instruments are considered viable for the measurement of high concentration tritiated water and have many potential benefits associated with their deployment.

A microfluidic analyzer based on liquid waveguide capillary cells for the high-sensitivity determination of phosphate in seawater and its applications

BackgroundOptical detection is frequently performed on microfluidic chips for colorimetric analysis. Integrating liquid waveguide capillaries with total internal reflection with the microfluidic chip requires less procedures, which is suitable in the optical detection of microfluidic systems and is a practical alternative to increase the optical path length in the colorimetric assay of microfluidic devices for higher sensitivities and lower detection limit. However, this alternative has not been applied to the connection of PMMA chips or the microfluidic devices for the detection of phosphate in seawater. ReslutsHere, a lab-on-a-chip system integrating a microfluidic chip and an external liquid waveguide capillary cell was presented to detect the phosphate in seawater. The detachable total internal reflection capillary made of Teflon AF 2400 connected to the chip transports sample and transmits light, greatly reducing detection limit, eliminating the interference from stray light and widening the dynamic range of the system without specific surface treatment of the microchannel. By utilizing an internal 5-cm absorption cell and an external 20-cm liquid waveguide capillary cell, the system reaches detection limits of 59 nM and 8 nM, respectively, and can detect phosphate concentration from 0 to 23 μM. An online analyzer was developed based on the high-sensitivity system and was applied to shipboard underway analysis for two scientific cruises and to laboratory measurements for seawater samples from Xisha sea area. SignificanceCorrelation analyses between the shipboard and laboratory phosphate measurements and other physical and biochemical elements revealed the marine ecological characteristics of the corresponding areas, demonstrating the high-sensitivity of this method over slight variations and narrow ranges of phosphate and the ability to provide microfluidic systems for high spatiotemporal resolution phosphate determination a practical and cost-effective alternative.

Liver-on-a-Chip Integrated with Label-Free Optical Biosensors for Rapid and Continuous Monitoring of Drug-Induced Toxicity.

Drug toxicity assays using conventional 2D static cultures and animal studies have limitations preventing the translation of potential drugs to the clinic. The recent development of organs-on-a-chip platforms provides promising alternatives for drug toxicity/screening assays. However, most studies conducted with these platforms only utilize single endpoint results, which do not provide real-time/ near real-time information. Here, a versatile technology is presented that integrates a 3Dliver-on-a-chip with a label-free photonic crystal-total internal reflection (PC-TIR) biosensor for rapid and continuous monitoring of the status of cells. This technology can detect drug-induced liver toxicity by continuously monitoring the secretion rates and levels of albumin and glutathione S-transferase α (GST-α) of a 3D liver on-a-chip model treated with Doxorubicin. The PC-TIR biosensor is based on a one-step antibody functionalization with high specificity and a detection range of 21.7ngmL-1 to 7.83 x 103ngmL-1 for albumin and 2.20ngmL-1 to 7.94 x 102ngmL-1 for GST-α. This approach provides critical advantages for the early detection of drug toxicity and improved temporal resolution to capture transient drug effects. The proposed proof-of-concept study introduces a scalable and efficient plug-in solution for organ-on-a-chip technologies, advancing drug development and in vitro testing methods by enabling timely and accurate toxicity assessments.

Performance parameters as a function of graphene’s chemical potential for SPR biosensor based on 2D materials

The present research analyze the performance parameters of a surface plasmon resonance (SPR) biosensor such as sensitivity, detection accuracy, quality factor, and combined sensitivity factor as a function of graphene chemical potential in a metal/2D material/graphene multilayer system. The attenuated total reflection of SPR was studied as a function of the number of graphene sheets for different 2D materials (ZnO, MoS2, MoSe2, WSe2, WS2) and calculated using the transfer matrix method. It was found that there is a critical value of the chemical potential for which the performance parameters change their behavior abruptly for all type of 2D materials used in the biosensor configuration; this chemical potential value is called critical chemical potential. Furthermore, the number of graphene sheets have a strong effect on the performance parameters. Finally, an analytical expression for the sensitivity was deduced, which allows to explain their behavior for the different 2D materials used in the SPR biosensor.

Salivary Molecular Spectroscopy with Machine Learning Algorithms for a Diagnostic Triage for Amelogenesis Imperfecta

Amelogenesis imperfecta (AI) is a genetic disease characterized by poor formation of tooth enamel. AI occurs due to mutations, especially in AMEL, ENAM, KLK4, MMP20, and FAM83H, associated with changes in matrix proteins, matrix proteases, cell-matrix adhesion proteins, and transport proteins of enamel. Due to the wide variety of phenotypes, the diagnosis of AI is complex, requiring a genetic test to characterize it better. Thus, there is a demand for developing low-cost, noninvasive, and accurate platforms for AI diagnostics. This case-control pilot study aimed to test salivary vibrational modes obtained in attenuated total reflection fourier-transformed infrared (ATR-FTIR) together with machine learning algorithms: linear discriminant analysis (LDA), random forest, and support vector machine (SVM) could be used to discriminate AI from control subjects due to changes in salivary components. The best-performing SVM algorithm discriminates AI better than matched-control subjects with a sensitivity of 100%, specificity of 79%, and accuracy of 88%. The five main vibrational modes with higher feature importance in the Shapley Additive Explanations (SHAP) were 1010 cm−1, 1013 cm−1, 1002 cm−1, 1004 cm−1, and 1011 cm−1 in these best-performing SVM algorithms, suggesting these vibrational modes as a pre-validated salivary infrared spectral area as a potential biomarker for AI screening. In summary, ATR-FTIR spectroscopy and machine learning algorithms can be used on saliva samples to discriminate AI and are further explored as a screening tool.

Efficient Redirection of Trapped Broad-Band Fluorescence from Substrates into Free Space Using c-Si Metasurfaces.

Fluorescent dye films on transparent substrates are essential for OLEDs, flexible displays, X-ray detection, and wireless optical communications. However, their efficiency is often hampered by fluorescence trapping due to total internal reflection (TIR) and waveguiding. This study tackles this longstanding challenge by reconceptualizing the integration of dye films with nanoantenna metasurfaces. Traditional methods involve directly spin-coating films onto c-Si metasurfaces on quartz substrates, resulting in edge luminescence and weak inner signals. We present a straightforward, adjustable approach by integrating dye films on the opposite side of quartz substrates, reaching a 2.5-fold photoluminescence enhancement and improving the uniformity of the emission compared to the conventional methods. These gains stem from redirecting a significant portion of leaked fluorescence light trapped inside the substrate into free space, surpassing TIR conditions through in-plane diffraction orders of the metasurfaces across the full RGB spectrum. Our findings facilitate the design of more efficient luminescent devices.

Lazerckerite, Ag3.75Pb4.5(Sb7.75Bi4)S24, from Kutná Hora, Czech Republic: a new Sb–Bi member of the andorite branch of the lillianite homologous series

Abstract. Lazerckerite, ideally Ag3.75Pb4.5(Sb7.75Bi4)S24, is a new mineral species found in medieval mine dumps of the historic Ag–Pb–Zn Kutná Hora ore district, Czech Republic. The mineral is associated with other Sb–Bi lillianite homologues (terrywallaceite, gustavite, holubite) and Ag,Bi-bearing galena, most frequently as grain aggregates and replacement rims of earlier Ag–Pb–Bi minerals, growing together in aggregates of up to 0.6×0.3 mm. Lazerckerite is opaque, is steel grey in colour, and has a metallic lustre; the calculated density is 5.920 g cm−3. In reflected light lazerckerite is greyish white, and bireflectance and pleochroism are weak with grey tints. Anisotropy is weak to moderate with grey to bluish-grey rotation tints. Internal reflections are not observed. Electron microprobe analyses yielded the empirical formula, based on 44 apfu, (Ag3.61Cu0.04)Σ3.65(Pb4.55Fe0.01Cd0.01)Σ4.57(Sb7.87Bi3.75)Σ11.62(S24.15Se0.01)Σ24.16. Its unit cell parameters are a=13.2083(9), b=19.4595(8), c=8.4048(13), β=90.032(7)°, V=2160.3(4) Å3, space group P21/c, and Z=2. The structure of lazerckerite contains two Pb sites (Pb1 and Pb2) in bicapped trigonal prismatic coordination, 8 independent octahedral sites, and 13 distinct sulfur positions. Four of the octahedral sites are mixed (Sb,Bi) and (Bi,Sb) sites, one is a mixed (Ag,Bi) site, and one is a mixed (Sb,Pb) site. The new mineral belongs to the andorite branch of the lillianite homologous series with N=4 and is a new addition to the group of Sb–Bi mixed members of the series. Lazerckerite is defined as a lillianite homologue with the three following requirements: N=4, L (Ag++ (Bi3+, Sb3+) ↔ 2 Pb2+ substitution) ≈ 90 %–95 %, and approximately one-third of atom percentage of antimony is replaced by bismuth (Bi/(Bi+Sb) ≈ 0.30–0.38). The new mineral has been approved by the Commission on New Minerals, Nomenclature and Classification (CNMNC) of the International Mineralogical Association (IMA 2022-113) and named after Lazarus Ercker, the supreme Royal Bergmeister of the Kingdom of Bohemia and the Master of Prague Mint.

Degradation of Amyloid-β Species by Multi-Copper Oxidases.

Reduction of the production of amyloid-β (Aβ) species has been intensively investigated as potential therapeutic approaches for Alzheimer's disease (AD). However, the degradation of Aβ species, another potential beneficial approach, has been far less explored. To investigate the potential of multi-copper oxidases (MCOs) in degrading Aβ peptides and their potential benefits for AD treatment. We investigated the degradation efficiency of MCOs by using electrophoresis and validated the ceruloplasmin (CP)-Aβ interaction using total internal reflection fluorescence microscopy, fluorescence photometer, and fluorescence polarization measurement. We also investigated the therapeutic effect of ascorbate oxidase (AO) by using induced pluripotent stem (iPS) neuron cells and electrophysiological analysis with brain slices. We discovered that CP, an important MCO in human blood, could degrade Aβ peptides. We also found that other MCOs could induce Aβ degradation as well. Remarkably, we revealed that AO had the strongest degrading effect among the tested MCOs. Using iPS neuron cells, we observed that AO could rescue neuron toxicity which induced by Aβ oligomers. In addition, our electrophysiological analysis with brain slices suggested that AO could prevent an Aβ-induced deficit in synaptic transmission in the hippocampus. To the best of our knowledge, our report is the first to demonstrate that MCOs have a degrading function for peptides/proteins. Further investigations are warranted to explore the possible benefits of MCOs for future AD treatment.

Covalent Organic Framework Stabilized Single CoN4Cl2 Site Boosts Photocatalytic CO2 Reduction into Tunable Syngas

Solar carbon dioxide (CO2) reduction provides an attractive alternative to producing sustainable chemicals and fuel. However, the construction of a highly active photocatalyst was challenging because of the rapid charge recombination and sluggish surface CO2 reduction. Herein, a unique Co‐N4Cl2 single site was fabricated by loading Co species into the 2,2'‐bipyridine and triazine‐containing covalent organic framework (COF) for CO2 conversion into syngas under visible light irradiation. The resulting champion catalyst TPy‐COF‐Co enabled a record‐high CO production rate of 426 mmol g‐1 h‐1, associated with the unprecedented turnover number (TON) and turnover frequency (TOF) of 2095 and 1607 h−1, respectively. The catalyst also exhibited favorable recycling performance and widely adjustable syngas production (CO/H2 ratio: 1.8:1‐1:16). A systematical investigation including operando synchrotron X‐ray absorption fine structure (XAFS) spectroscopy, in‐situ attenuated total reflection surface‐enhanced infrared absorption spectroscopy (ATR‐SEIRAS), and theoretical calculation indicated that the triazine‐based COF framework promoted the charge transfer towards the single Co‐N4Cl2 sites that greatly promoted the CO2 activation by lowering the energy barrier of *COOH generation, facilitating the CO2 transformation. This work highlights the great potential of the molecular regulation of COF‐derived single‐atom catalysts to boost CO2 photoreduction efficiency.

Observing multi-frequency structured illumination patterns based on an evanescent field in a millimeter-scale polymer slide.

Millimeter-scale slide optical waveguides (OWGs) show the potential to break the barrier of easy-to-use and versatility for total internal reflection (TIR) fluorescence technology. In this paper, multi-frequency structured illumination (SI) patterns resulting from the evanescent field (EF) on the surface of a millimeter-scale polymer slide OWG are observed by measuring the fluorescence intensity distribution of fluorescent dyes deposited on the top of the OWG. The frequency, intensity, and stability of the SI patterns show a strong dependence on the coupling angle of the incident light (changing with the incident position). The distribution of multi-frequency SI patterns in the frequency space is demonstrated for different numerical aperture (NA) imaging systems (NA = 0.3, 0.6, and 0.8), indicating the potential for enhanced resolution for low NA systems with a simple and cheap polymer slide.

Investigating the effect of gliding discharge plasma on polystyrene and Polyamide6 by positron annihilation lifetime spectroscopy

Polymers are widely used today and the changes in their properties are investigated by different methods such as plasma irradiation. One of the most important methods for modifying polymers is cold plasma, by which the surface properties of the polymers can be changed under atmospheric pressure. In this study, the effect of plasma on Polystyrene (PS) and Polyamide 6 (PA6) samples was investigated. Surface and depth changes of the PS and PA6 have been investigated by various experimental techniques such as Fourier Transform Infrared (FTIR), X-ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), Contact Angle (CA), and Positron Annihilation Lifetime Spectroscopy (PALS). The results of Attenuated Total Reflectance (ATR)-FTIR show that the chemical bonds of PA6 have been changed, and preserved in PS in the depths. The XRD results show that there are no volume changes for chemical bands. The FESEM analysis results reveal that the plasma causes digging and creates roughness on the surface. The CA measurement confirms the FESEM results and points out an increase in hydrophobicity after plasma processing. The PALS results indicate that the free volumes of the matter are changed after plasma irradiation in the depths of PS and PA6. In addition, the plasma also causes changes in the micrometer depth.