Absorption Cell Research Articles

Investigation of the physicochemical, cytotoxic, and antimicrobial properties of a resin-based pulp capping material incorporated with calcium fructoborate-loaded mesoporous silica nanoparticles.

Investigation of the physicochemical, cytotoxic, and antimicrobial properties of a resin-based pulp capping material incorporated with calcium fructoborate-loaded mesoporous silica nanoparticles.

Extending the optical path of segmented circular multipass cells by reiteration of reflection patterns.

This Letter presents a novel, to the best of our knowledge, design element for the segmented circular multipass cell (SC-MPC) concept, which enables a substantial increase in optical path length without enlarging the cell footprint or sampling volume. It features a specific tilt of individual mirror segments within the cell to repeatedly redirect the laser beam propagation from one starlike pattern to another, thereby achieving multiple uses of mirror segments. We present the theoretical foundations, outline the pattern selection process, and characterize the resulting individually tilted segmented circular multipass cell (iSC-MPC) in a spectroscopic setting. The results demonstrate optical performance comparable to classical two-mirror long-path length absorption cells, but within a substantially smaller footprint. This compactness offers an inherent mechanical stability and robustness paired with high versatility, which makes the iSC-MPC highly potential for a wide range of applications.

Pressure-induced structural phase transitions in CrSBr

There is growing interest in combining chemical complexity with external stimuli like pressure, field, and light for property control in van der Waals solids. This is because extreme conditions trigger the development of new states of matter and functionality. In this work, we bring together synchrotron-based infrared absorption, Raman scattering, and diamond anvil cell techniques with first-principles calculations of the lattice dynamics and energy landscape to reveal the series of structural phase transitions in CrSBr. By tracking how the phonons change under pressure, we uncover a remarkable chain of complex symmetry modifications, interlayer interactions, and chemical reactions. A group-subgroup analysis suggests that CrSBr undergoes an orthorhombic Pmmn → monoclinic P2/m transition at 7.6 GPa, and based upon a comparison with model oxychlorides like FeOCl and CrOCl, we propose that changes in the pendant halide groups drive the system to a P21/m-like space group above 15.3 GPa. Compression above 20.2 GPa is irreversible, resulting in the formation of an entirely new compound that is metastable for months. This work opens the door to the use of pressure and possibly strain to control the properties of CrSBr.

Investigation of the Influence of Donor and Internal Acceptor on Photovoltaic Parameters in D-A1-π-A Dye Sensitizers for efficient DSSCs.

Investigation of the Influence of Donor and Internal Acceptor on Photovoltaic Parameters in D-A1-π-A Dye Sensitizers for efficient DSSCs.

Preparation and characterization of biodegradable flexible polyurethane foam containing acetylated tapioca starch and Castor oil

This research project focused on developing flexible polyurethane foams with high biodegradability, suitable as substrates for growing vegetables or cereal sprouts. These foams incorporated acetylated tapioca starch as a filler and castor oil, and their properties were evaluated. Experiments assessed how varying concentrations of acetylated starch (0, 15, 30, 45, and 60 wt%) and castor oil (0, 10, 20, and 30 wt%) affected the foams’ density, tensile properties, compression set, moisture absorption, biodegradability, and microstructure. Results indicated that increasing acetylated starch concentration led to higher density, compression set, biodegradability, and closed cell percentage, while tensile strength, elongation at break, water absorption, and mean cell diameter decreased. Most changes were significant (p < 0.05), with density, compression set, biodegradability, tensile strength, elongation at break, water absorption, and average cell diameter being 21.7 kg/m2, 11.4%, 9.2%, 101.4 kPa, 97.2%, 3820%, and 0.34 mm respectively, for foam without castor oil and acetylated starch compared to 33.1 kg/m2, 19.7%, 37.7%, 62.3 kPa, 28.9%, 2600%, and 0.186 mm for foam with 60 wt% acetylated starch, respectively. The influence of castor oil concentration on the foams’ physical and mechanical properties was inconsistent. Additionally, the germination amount of grown green basil seeds on commercial flexible polyurethane foam was higher than that of selected prepared foam (84.7% vs. 81.3%), but the germination rate of grown green basil seeds on selected prepared foam was higher than that of commercial foam at all times, including the ninth day (4.7 vs. 4.2 cm).

Viper: High-precision radial velocities from the optical to the infrared

Context. High-precision radial velocity (RV) measurements with slit spectrographs require the instrument profile (IP) and Earth’s atmospheric spectrum to be known and to be incorporated into the RV calculation. Aims. We developed an RV pipeline, called Velocity and IP EstimatoR (viper), to achieve high-precision RVs in the near-infrared (NIR). The code is able to process observations taken with a gas cell and includes modelling of the IP and telluric lines. Methods. We utilised least-square fitting and telluric forward modelling to account for instrument instabilities and atmospheric absorption lines. As part of this process, we demonstrate the creation of telluric-free stellar spectra. Results. By applying viper to observations obtained with the upgraded CRyogenic high-resolution InfraRed Echelle Spectrograph (CRIRES+) and a gas absorption cell in the K band, we are able to reach an RV precision of around 3 m/s over a time span of 2.5 years. For observations using telluric lines for the wavelength reference, an RV precision of 10 m/s is achieved. Conclusions. We demonstrate that despite telluric contamination, a high RV precision is possible at NIR wavelengths, even for a slit spectrograph with varying IP. Furthermore, we show that CRIRES+ performs well and is an excellent choice for science studies requiring precise stellar RV measurements in the infrared.

Validation of the ESPRESSO wavelength calibration using iodine absorption cell spectra

ABSTRACT High-quality wavelength calibration is crucial for science cases like radial-velocity studies of exoplanets, the search for a possible variation of fundamental constants, and the redshift drift experiment. However, for state-of-the-art spectrographs, it has become difficult to verify the wavelength calibration on sky because no astrophysical source provides spectra with sufficiently stable or accurate wavelength information. We therefore propose to use iodine absorption cells to validate the wavelength calibration. Observing a bright and featureless star through the iodine cell emulates an astrophysical target with exactly known spectral features that can be analysed like any other science target, allowing to verify the wavelength calibration derived from the internal calibration sources and to identify systematics in the data processing. As demonstration, we temporarily installed an $\mathrm{I_2}$ absorption cell at ESPRESSO. Employing a full forward modelling approach of the $\mathrm{I_2}$ spectrum, including the instrumental line-spread function, we demonstrate wavelength calibration accuracy at the level of a few $\mathrm{m\,s^{-1}}$. We also show that wavelength measurements do depend on the geometry of the light-injection into the spectrograph fibers. This highlights the importance of probing exactly the same light path as science targets, something not possible with internal calibration sources alone. We also demonstrate excellent radial-velocity stability at the ${{&amp;lt; 20\, \mathrm{cm\,s^{-1}}}}$ level in a full end-to-end fashion, from sky to data product. Our study therefore showcases the great potential of absorption cells for the verification and long-term monitoring of the wavelength calibration as well as the unique insights they can provide.

Enhanced biological properties of polyvinyl alcohol-polycaprolactone/hyaluronic acid-coated electrospun scaffolds for articular cartilage regeneration

This study provides a cohesive framework to putting forth PVA-PCL scaffolds coated with hyaluronic acid (HA) hydrogel to mimic the characteristics of articular cartilage, as a cost-effective tissue engineering alternative. PVA and PCL solutions were prepared and electrospun under measured conditions, with parameters adjusted to fabricate aligned and random fiber orientations. Afterward, the scaffold was integrated with the optimal hydrogel, selected for its superior water absorption and hydrophilicity. The thickness of the hydrogel layer satisfied the criteria for supporting chondrocyte function, and the study assesses its effect on cell viability. Scaffolds were characterized using field emission scanning electron microscopy (FE-SEM) for morphology, energy-dispersive X-ray spectroscopy (EDX) for elemental analysis, Fourier transform infrared (FTIR) spectroscopy for chemical composition, and tensile tests for mechanical behavior. The surface wettability was determined by contact angle measurements. Biological properties were assessed through cytotoxicity, protein absorption assays and cell adhesion tests with visualization of cell distribution using DAPI staining, fluorescence microscopy, and FE-SEM. Using a hydrolytic mechanism, biodegradation was assessed using pH variations and weight loss measurements. Accordingly, randomly oriented hydrogel-coated scaffolds yielded the most favorable biological outcomes to produce a tissue-friendly, biologically robust graft that closely mimics the natural cartilage extracellular matrix. The pore size and distribution of these scaffolds were more uniform than those of aligned structures. The findings suggest possibilities for customizing scaffold properties through fiber orientation, polymer blending, and surface coating to optimize cell response and tissue formation. Combining electrospun PVA-PCL with chondrocytes-seeded hydrogels offers a way to improve articular cartilage regeneration.

Non-axial optical design of multi-pass spectral absorption cell: algorithms

Non-axial optical design of multi-pass spectral absorption cell: algorithms

Research of Enhancing the Light Absorption and Strengthen GaAs Thin Film Solar Cells with Metallic Ti Material Based on Grating Structure and Surface Plasmon Resonance Effect

Research of Enhancing the Light Absorption and Strengthen GaAs Thin Film Solar Cells with Metallic Ti Material Based on Grating Structure and Surface Plasmon Resonance Effect

CH4, C2H6, and C2H4 Multi-Gas Sensing Based on Mid-Infrared Spectroscopy and SVM Algorithm.

A multi-gas sensing system based on mid-infrared spectral absorption was developed for the detection of CH4, C2H6, and C2H4. The system utilized a broadband infrared source, a hollow waveguide (HWG) absorption cell, and a tunable Fabry-Pérot (FP) detector. The limits of detection (LODs) of CH4, C2H6, and C2H4 were 7.33 ppm, 2.13 ppm, and 8.09 ppm, respectively. For multi-gas measurements, the support vector machine (SVM) algorithm model was employed to calculate the concentration of each component. The root mean square error of prediction (RMSEP) values for CH4, C2H6, and C2H4 were 15.91 ppm (1.26%), 1.64 ppm (0.57%), and 6.95 ppm (0.55%), respectively. The generation of stimulated absorption spectra of mixed gases was realized, and the sample selection of measurement for accurate concentration calculation of each gas was optimized. The system proposed in this work provides a simple, miniaturized, and cost-effective solution for multi-gas sensing.

Effect of Folic Acid and Ascorbic Acid Supplementation on Hematological Parameters of Male Rabbits

Ascorbic acid (Vitamin C) and folic acid (Vitamin B9) are essential micronutrients involved in hematopoiesis, immune function, and antioxidant defense. Ascorbic acid enhances iron absorption and red blood cell (RBC) production, while folic acid is crucial for DNA synthesis and erythropoiesis. Deficiencies in these vitamins are associated with anemia and impaired immune responses. This study investigates the effects of ascorbic acid, folic acid, and their combination on hematological parameters in male rabbits, focusing on hemoglobin (Hb), RBC count, white blood cell (WBC) count, platelets (PLAT), and hematocrit (HCT). Male rabbits were divided into four experimental groups: control, ascorbic acid, folic acid, and a combination of both. Hematological parameters were assessed after treatment, and statistical significance was evaluated. The findings demonstrated that supplementation with ascorbic acid and folic acid significantly improved Hb and RBC counts compared to the control, suggesting enhanced erythropoiesis. The combination group exhibited the highest RBC count (8.60 ± 0.417 ×10⁶/µl), indicating a potential synergistic effect. The WBC count decreased in the folic acid group but remained stable in the ascorbic acid and combination groups, suggesting an immunomodulatory role. Platelet counts increased significantly in the combination group (489.12 ± 209.7 ×10³/µl), highlighting a possible stimulatory effect on megakaryocyte maturation. HCT levels were highest in the combination group (39.66 ± 1.016 ×10³/µl), indicating improved oxygen-carrying capacity.

Hyperspectral analysis to assess gametocytogenesis stage progression in malaria-infected human erythrocytes.

Developments of anti-gametocyte drugs have been delayed due to insufficient understanding of gametocyte biology. We report a systematic workflow of data processing algorithms to quantify changes in the absorption spectrum and cell morphology of single malaria-infected erythrocytes. These changes may serve as biomarkers instrumental for the future development of antimalarial strategies, especially for anti-gametocyte drug design and testing. Image-based biomarkers may also be useful for nondestructive, label-free malaria detection and drug efficacy evaluation in resource-limited communities. We extend the application of hyperspectral microscopy to provide detailed insights into gametocyte stage progression through the quantitative analysis of absorbance spectra and cell morphology in malaria-infected erythrocytes. Malaria-infected erythrocytes at asexual and different gametocytogenesis stages were imaged through hyperspectral confocal microscopy. The preprocessing of the hyperspectral data cubes to transform them to color images and spectral angle mapper (SAM) analysis were first used to segment hemoglobin (Hb)- and hemozoin (Hz)-abundant areas within the host erythrocytes. Correlations between changes in cell morphology and increasing Hz-abundant areas of the infected erythrocytes were then examined to test their potential as optical biomarkers to determine the progression of infection, involving transitions from asexual to various gametocytogenesis stages. Following successful segmentation of Hb- and Hz-abundant areas in malaria-infected erythrocytes through SAM analysis, a modest correlation between the segmented Hz-abundant area and cell shape changes over time was observed. A significant increase in both the areal fraction of Hz and the ellipticity of the cell confirms that the Hz fraction change correlates with the progression of gametocytogenesis. Our workflow enables the quantification of changes in host cell morphology and the relative contents of Hb and Hz at various parasite growth stages. The quantified results exhibit a trend that both the segmented areal fraction of intracellular Hz and the ellipticity of the host cell increase as gametocytogenesis progresses, suggesting that these two metrics may serve as useful biomarkers to determine the stage of gametocytogenesis.

Improvement in the Sagnac-loop laser frequency stabilization

The laser frequency stability locked to the D2 transition of 85Rb at 780 nm using a Doppler-free Sagnac-loop stabilization scheme has been improved. In a previous work [J. Opt. Soc. Am. B 40, 667 (2023)JOBPDE0740-322410.1364/JOSAB.482223], changes in birefringence at the absorption cell windows, influenced by the cell temperature, and in the rubidium vapor, affected by magnetic field fluctuations, significantly influenced the laser frequency stability. By aligning the polarization, the short-term stability (&lt;10s) of the locked laser frequency was improved; however, the long-term stability remained unaffected. We attribute this long-term stability to temperature-induced changes in the optical path length of the wave plates. By removing the wave plates from the setup, the long-term stability has been successfully improved.

Enhancing Gas Diffusion in Antiresonant Hollow-Core Fiber Gas Sensors Using Microchannels

In this paper, we analyze the performance of diffusion-based gas distribution in antiresonant hollow-core fiber-based gas absorption cells. Performed theoretical analysis was based on Fick’s second law using the OpenFOAM® software and finite volume method (FVM), followed by an experimental verification of the obtained simulations. The diffusion time was tested for a 1.25 m long fiber, with laser-micromachined microchannels. Full analysis of the correlation between the microchannel count, position, and separation on the rate at which the fiber-based gas cell was filled with the target gas was presented. Experimental results showed that with the proper microchannel configuration, the purely-diffusion-based gas exchange time in the 1.25 m fiber could be reduced from 6 h, down to 330 s. Obtained results correlated with the simulations, giving perspective for the development and implementation of novel miniaturized passively filled gas absorption cells for compact laser spectrometers.

Enhancement of Methane Detection in Tunable Diode Laser Absorption Spectroscopy Using Savitzky–Golay Filtering

In order to enhance gas absorption efficiency and improve the detection sensitivity of methane, a gas absorption cell with an effective optical path length of 29.37 m was developed, employing tunable diode laser absorption spectroscopy (TDLAS) and a distributed feedback (DFB) laser with a center wavelength of 1.654 μm as the light source. However, despite these advancements, the detection accuracy was still limited by potential signal interference and noise. To address these challenges, the Savitzky–Golay (S-G) filtering technique was implemented to optimize the TDLAS detection signal. Experimental results indicated a significant enhancement in detection performance. For a methane concentration of 92 ppm, the application of the S-G filter improved the signal-to-noise ratio by a factor of 1.84, resulting in a final device detection accuracy of 0.53 ppm. This improvement demonstrates the effectiveness of the S-G filter in enhancing detection sensitivity, supporting high-precision methane monitoring for atmospheric analysis and various industrial applications.

Diode Laser Absorption Sensor for Ammonia Detection in a Shock Tube

With the improved availability and performance of low-cost near-infrared diode lasers, quantitative assessment of ammonia (NH3) as a carbon-free fuel has been made more accessible and affordable in both laboratory research and field applications. In the present study, an absorption sensor for NH3 measurement was developed by exploiting the affordability and flexibility of a near-infrared fiber-coupled distributed feedback diode laser. The first objective of the present study was to address the incomplete spectroscopic data for the absorption feature near 2.2 μm through the determination of line strengths and broadening coefficients with collisional partners including NH3, O2, N2, and Ar. Line shape characterization in both an absorption cell and a shock tube behind reflected shock waves was conducted to determine the temperature exponents of these broadening coefficients. The other objective was to demonstrate the capability of the sensor through NH3 detection in multicomponent mixtures and NH3 time-history measurements in the shock tube for investigating NH3 chemical kinetics at engine and gas-turbine-relevant conditions. The NH3 sensor developed in this study could serve as a cost-effective diagnostic tool for chemical kinetic measurements, combustion monitoring, and other applications where flexibility and robustness are prioritized.

Morphological analysis reveals the influence of genipin and polyvinyl alcohol on porous morphology on interpenetrated chitosan xerogels

The morphological characterization of xerogels composed of chitosan, genipin, and PVA demonstrates that their porous architecture is essential to their function as scaffolds for tissue engineering, with significant impacts on absorption properties, cell viability, and potential for biomedical application. SEM and microCT analysis confirmed that these xerogels possess a highly porous internal morphology, with interconnected pores forming an interpenetrating polymeric network, free from phase separation between chitosan and PVA. Hemocompatibility assays confirmed the non-cytotoxic nature of these materials. Varying genipin concentrations showed that lower concentrations produce more heterogeneous pore sizes, while higher concentrations yield a uniform pore distribution, likely due to the increased availability of crosslinking sites. Additionally, the degree of anisotropy increases with both higher genipin and PVA concentrations, suggesting enhanced alignment within the three-dimensional structure. The total open pore volume, which ranges from 88% to 93%, is modifiable based on the concentrations of genipin and PVA. These insights indicate that these xerogels are viable candidates for clinical applications, particularly as potential substitutes for nucleus pulposus, given their high swelling capacity, porosity, interconnectivity, biocompatibility, and adaptable morphological characteristics.

A Systematic Review of Isotopically Measured Iron Absorption in Infants and Children Under 2 Years.

Iron is an essential element for critical biological functions, with iron deficiency negatively affecting growth and brain development and iron excess associated with adverse effects. The goal of this review is to provide a comprehensive assessment of up-to-date evidence on iron absorption measured isotopically in children, preterm infants, and full-term infants, up to 24 months of age. Search databases included Pubmed, Cochrane, Web of Science, and Scopus from a date range of 1 January 1953 to 22 July 2024. The included articles were experimental studies with iron absorption outcomes measured by isotopic techniques. The risk of bias was assessed using the Cochrane Risk of Bias Tool. A total of 1594 records were identified from databases, and 37 studies were included in the quality review with a total of 1531 participants. Article results were grouped by study commonality: absorption and red blood cell incorporation, type of milk feedings, additives to improve absorption, how and when to supplement with iron, and iron forms and complimentary foods. The results from this review support the current recommendations of oral iron supplementation. Iron from breast milk has high bioavailability, and unmodified cow's milk reduces iron absorption. Supplemental iron is required at 4-6 months for healthy, full-term infants and sooner for preterm infants. Ascorbic acid increases iron absorption in full-term infants and children. Lactoferrin and prebiotics are promising candidates for enhancing iron absorption, but they require further investigation. Research evidence of iron absorption mechanisms and modulating factors in preterm infants is limited and should be a research priority.

Calibration experiments for dual-comb IPDA XCO2 measurements using a variable pressure absorption cell

Calibration experiments for dual-comb IPDA XCO2 measurements using a variable pressure absorption cell