Transmittance Technique Research Articles

Volume Regulation and Nonosmotic Volume of Individual Human Platelets Quantified by High-Speed Scanning Ion Conductance Microscopy.

Platelets are anucleate cells that play an important role in wound closure following vessel injury. Maintaining a constant platelet volume is critical for platelet function. For example, water-induced swelling can promote procoagulant activity and initiate thrombosis. However, techniques for measuring changes in platelet volume such as light transmittance or impedance techniques have inherent limitations as they only allow qualitative measurements or do not work on the single-cell level. Here, we introduce high-speed scanning ion conductance microscopy (HS-SICM) as a new platform for studying volume regulation mechanisms of individual platelets. We optimized HS-SICM to quantitatively image the morphology of adherent platelets as a function of time at scanning speeds up to 7 seconds per frame and with 0.1 fL precision. We demonstrate that HS-SICM can quantitatively measure the rapid swelling of individual platelets after a hypotonic shock and the following regulatory volume decrease (RVD). We found that the RVD of thrombin-, ADP-, and collagen-activated platelets was significantly reduced compared with nonactivated platelets. Applying the Boyle-van't Hoff relationship allowed us to extract the nonosmotic volume and volume fraction on a single-platelet level. Activation by thrombin or ADP, but not by collagen, resulted in a decrease of the nonosmotic volume, likely due to a release reaction, leaving the total volume unaffected. This work shows that HS-SICM is a versatile tool for resolving rapid morphological changes and volume dynamics of adherent living platelets.

Characterization of aerosol and its oxidative potential in a coastal semi-rural site of Southern Italy

Considering the scarce number of studies investigating the oxidative potential of PM2.5 in Italy, a measurement campaign was conducted from February 2020 to October 2020 in a coastal semi-rural site of Basilicata (Southern Italy) with the goal to characterize the fine fraction of ambient particulate matter (PM) and investigate its chemical and toxicological properties, by means of oxidative potential. Different instruments such as an automatic low-volume sampler, an aethalometer and an optical particle counter, were employed for the measurement of PM2.5 mass concentration, equivalent black carbon (eBC) concentration and absorption Ångström exponent (AAE), and particle number size distribution in 0.25–31 μm size range, respectively. 108 daily PM samples, collected on quartz fibre filters, were chemically analysed. Organic (OC) and elemental (EC) carbon content was estimated by thermo-optical transmittance technique (TOT), the concentrations of the main water-soluble ions and total elements were determined by ion chromatography and ED-XRF technique, while the oxidative potential of the water-soluble fraction was estimated through the dithiothreitol (DTT) assay. The mean value of PM2.5 mass concentration was 9.2 ± 2.5 μg/m3 and the average contribution of measured species on PM2.5 mass was 3.3% EC; 19.3% OC; 27.0% secondary inorganic aerosol (sum of SO42−, NH4+ and NO3−), and 10.2% of the other ions and elements. The OC and EC contributions to PM2.5 mass and their mean ratio (OC/EC = 6.6 ± 3.1) suggest that the site is affected by the combined contribution of traffic emissions and biomass combustion (domestic heating and agricultural activities), with the latter prevailing over the traffic, as supported by the mean AAE value of 1.3. The mean OP normalized by sampled volume, OPDTTV, was as high as 0.34 ± 0.22 nmol/min·m3, a value comparable to those recorded for PM2.5 in suburban areas of Italy. The correlation between OPDTTV and the chemical species observed in the PM2.5 samples showed a good agreement with the carbonaceous component OC (r = 0.62) and with some ions, K+ and SO42− (r = 0.60). These results identify combustion sources as the most responsible for the relatively high OPDTTV activity of PM2.5 recorded in this area.

Characterizing the Thickness Distribution of Donor and Acceptor in Organic Photovoltaics via Quasi‐Monochromatic Light Transmittance

AbstractThe performance of organic solar cells is sensitive to the film thickness and the uniformity of the donor and acceptor distribution in the photoactive layer. Especially, in the quasi‐planar heterojunction fabricated by layer‐by‐layer process, the donor and acceptor materials may be non‐homogeneously distributed across the entire photoactive layer. Visualization of the spatial distributions of donor and acceptor components sheds light on the relationship between nanostructures and device performances. Based on the distinct infrared absorption characteristics of the organic donor and acceptor, a quasi‐monochromatic light transmittance (QMLT) technique is proposed to quantify the donor and/or acceptor thickness in the photoactive layer blend across the entire device area with nanometer precision. The variation in thickness of donor and acceptor can be clearly and separately revealed. Accordingly, the impacts of spin coating techniques (such as dynamic or static dispensing, and on‐center or off‐center spin coating), as well as solvent choices, on film morphology and device performance can be correlated by the noncontact, nondestructive, and convenient QMLT method.

Characterisation of vehicle emissions in a road tunnel in Lisbon

In urban areas, road traffic is one of the main sources of air pollutants, mainly as particulate matter (PM). Knowledge about fingerprints of vehicle emissions under real-world driving conditions is scarce for Europe, especially in Portugal. The aim of this study was to characterise and quantify vehicle emissions through road tunnel measurements. The sampling campaign was carried out during one week inside a road tunnel and simultaneously in an urban background site in Lisbon. PM2.5 and PM2.5–10 filters were analysed by PIXE for elemental composition and by a thermal-optical transmittance technique for the determination of organic carbon (OC) and elemental carbon (EC). PM2.5 and PM10 concentrations were, at least, 20 and 10 times higher than those found in the background, respectively. Inside the tunnel, particle organic matter (POM), EC and other anthropogenic compounds accounted for more than 90.0% of the PM2.5 mass. Fe, Ca, Si, S and Cu represented 88.7% of the PM2.5-bound elements, while Fe, Cl, Ca, Si, Cu, Zn, Na, S, Ba mostly contributed to the PM2.5–10 elemental mass fraction (93.8%). Total carbon represented about 58.5% of PM2.5 and 26.5% of PM2.5–10. EC presented a high tunnel/background ratio (T/B = 35.4 for PM2.5 and 48.8 for PM2.5–10). Cu, Fe, Cr, Ba, Mn, Zn and Rb, which are key tracers of tyre and brake wear, showed a T/B > 70 and very good correlations between them. The emission factors (EF) of PM2.5 and PM10 were estimated to be 139 ± 20.7 and 172 ± 23.9 mg veh−1 km−1. The average EF of OC and EC in PM2.5 were 30.9 ± 6.48 and 44.6 ± 7.33 mg veh−1 km−1. This real-world study contributes to define road traffic emission profiles in urban areas, provide data to update European emission inventories, and evaluate the impact of traffic-generated PM on human health and the environment.

Asphaltene Inhibitor Screening of Next Generation: Automated High-Throughput Experimentation Method

Asphaltene deposition has been a critical flow assurance challenge, and chemical treatment with continuous asphaltene inhibitor injection has been the go-to approach for operators to preemptively tackle this challenge. Development of the right inhibitor chemistry and dosage is challenging and critical. A smart, automated process for screening numerous asphaltene inhibitor formulations based on the design of experiment (DoE) and high-throughput experimentation (HTE) method has been developed and is discussed in this work. Asphaltene inhibitor formulations with distinct base chemistries, boosters, and solvent packages were blended in various ratios to encompass a large chemical and formulation space with the automated blending station of the HTE setup. These formulations were then dosed into a multitude of crude oil samples produced from different regions of the world at constant dosages to represent a uniform and comparable test fluid matrix. The dispersion state of asphaltene clusters within dosed oil samples, in their native state, was then evaluated using the HTE-asphaltene differential aggregation probe test (ADAPT) techniques to generate thousands of performance data points. Furthermore, the efficiency of top-performing formulations was then cross-validated using standard optical transmittance and deposition-based techniques to gauge performance. The four main pillars of the HTE technique are automation, miniaturization, parallelization, and computational design. Each of these pillars contributes to enhancing the current test method into a more accurate, agile, and quicker technique. Through automation, the overall accuracy of formulation blending as well as performance efficiency measurement is increased. With miniaturization, the resource consumption of raw materials and more importantly crude oil is considerably reduced. For this work, each formulation required less than 300 µL of oil per measurement. Parallelization resulted in completing the test evaluation at a rate of 600 evaluations every 4 hours. These results can then be analyzed through the computational design and analytics software to identify the top-performing formulations along with predicting the optimal chemical formulation space that can lead to maximum performance efficiency. The selected formulations were subsequently blended on a bigger laboratory scale, and their efficacy was cross-checked with both dispersion- (optical transmittance and thermoelectric methods) and deposition-based (flow loop setup) techniques against a benchmark asphaltene inhibitor product, known to work successfully in many fields having asphaltene instability related issues. Through this process, several new asphaltene inhibitor formulations were discovered that outperformed the benchmark blend. Automated HTE technology provides a new dimension to asphaltene inhibitor development work that can carry out performance evaluation of numerous formulations at tremendous speed and minimum crude oil volume. With this technique, one can quickly adapt to the changing requirements of asphaltene inhibitor and its dosage with varying crude oil composition, gas/oil ratio, water cut, or any operational change affecting overall asphaltene stability.

Recyclable luminescent carbon dots nanopaper for flexible electronics

The use of sustainable materials in high-tech devices is one way to decrease the carbon footprint and tackle global climate change. We first synthesized blue-emissive carbon dots (CDs) from biocompatible onion inner epidermal cells using solvothermal method. Then, cellulose nanofiber was prepared by TEMPO oxidization, followed by homogenization from soft wood source. Finally, the blue emissive CDs-cellulose nanofibers-based nanopaper was fabricated by simple roller-coating approach, and its optical and morphological properties were investigated by transmittance, photoluminescence, fourier-transform infrared (FTIR) and scanning electron microscopy techniques. The results indicate that nanopapers have a high light emission, and that their transparency may be easily adjusted by varying the proportion of CDs content. These nanopapers can be incorporated into flexible and stretchable electronics and optical sensor platforms.

Determining local modulus and strength of heterogeneous films by force-deflection mapping of microcantilevers.

Estimating the elastic modulus and strength of heterogeneous films requires local measurement techniques. For local mechanical film testing, microcantilevers were cut into suspended many-layer graphene using a focused ion beam. An optical transmittance technique was used to map thickness near the cantilevers, and multipoint force-deflection mapping with an atomic force microscope was used to record the compliance of the cantilevers. These data were used to estimate the elastic modulus of the film by fitting the compliance at multiple locations along the cantilever to a fixed-free Euler-Bernoulli beam model. This method resulted in a lower uncertainty than is possible from analyzing only a single force-deflection. The breaking strength of the film was also found by deflecting cantilevers until fracture. The average modulus and strength of the many-layer graphene films are 300 and 12GPa, respectively. The multipoint force-deflection method is well suited to analyze films that are heterogeneous in thickness or wrinkled.

Enhancement of birefringence for liquid crystal with the doping of ferric oxide nanoparticles

Electro-optical (E-O) property of nematic liquid crystalline (NLC) materials is the key parameter of display and non-display applications. Optical anisotropy (i.e., birefringence) is one of the critical parameters of these LCs via which E-O properties are governed. In this article, we have investigated the effect of ferric oxide nanoparticles (Fe2O3 NPs) on the birefringence and the order parameter of a NLC when doped into different weight percentages (wt%). The birefringence of the NLC has been examined via the phase modulation optical transmittance technique. It is noticed that the value of birefringence increases with the concentration of NPs in the LC matrix which is analogous to an improved order parameter of NLC after the addition of NPs. The improved ordering of LC molecules has been verified using polarized optical microscopy. This study helps in understanding the guest-host interactions for improved optical applications of LC materials.

Observation and analysis of nonlinear scattering using the scattered-light imaging method

Optical phenomena like nonlinear absorption and nonlinear refraction are often determined through light transmittance techniques. However, in turbid or resonant media, scattering may also significantly attenuate the laser beam, such that absorptive losses may be overestimated. Thus, while transmittance techniques are suitable to determine the power extinction, it is often difficult to characterize the contribution of nonlinear scattering in a sample. In this work we applied the scattered-light imaging method to discriminate the nonlinear extinction due to nonlinear absorption and nonlinear scattering contributions in a turbid medium constituted of ${\mathrm{TiO}}_{2}$ nanoparticles suspended in acetone. The single-shot method collects an image of the beam transverse profile evolution along the propagation axis inside the sample. It was observed that while the results obtained by the transmittance technique indicate the extinction coefficient (including scattering and absorption contributions), the results obtained with the scattered-light imaging method discriminate the contribution of each phenomenon. Therefore, the results of both approaches are complementary and allow a more complete characterization of turbid media.

Source identification and ambient trace element concentrations of PM10 using receptor modeling in an urban area of Chhattisgarh, India

This study investigated seasonal variation in PM10 aerosols and associated trace metal concentrations in an urban city Raipur, India. PM10 aerosols were monitored at Raipur for the year 2015 to 2019. Eighteen trace elements (Al, Ba, Ca, Cr, As, Mn, Sb, Se, Sr, Cu, Fe, Ga, Mg, Ni, Ti, V, Pb, Zn) and (EC and OC) were analyzed using atomic absorption spectroscopy and thermal optical transmittance technique. A receptor-based positive matrix factorization (PMF) model was used to identify the possible sources with qualitative analysis of crustal enrichment factor, back-trajectory analysis using concentration weighted trajectory (CWT) to predict potential locations of distant sources, and correlation between different species. The average PM10 aerosol mass concentration during the study period was found to be 184.91 ± 114 µg/m³. Seasonally, the average winter–time PM10 concentration (193.49 ± 129.18 µg/m³) was found higher as compared to summer time (176.32 ± 65.80 µg/m³) during the study period. Five sources were identified including the iron and steel industry (30%), biomass and waste combustion (28.7%), vehicular emissions (21%), heavy oil combustion (17.4%), and crustal dust (2.9%). The study provides information on major sources affecting air quality.

Geometry-dependent two-photon absorption followed by free-carrier absorption in AlGaAs waveguides

Nonlinear absorption can limit the efficiency of nonlinear optical devices. However, it can also be exploited for optical limiting or switching applications. Thus, characterization of nonlinear absorption in photonic devices is imperative for designing useful devices. This work uses the nonlinear transmittance technique to measure the two-photon absorption coefficients ( α 2 ) of AlGaAs waveguides in strip-loaded, nanowire, and half-core geometries in the wavelength range from 1480 to 1560 nm. The highest α 2 values of 2.4, 2.3, and 1.1 c m / G W were measured at 1480 nm for 0.8-µm-wide half-core, 0.6-µm-wide nanowire, and 0.9-µm-wide strip-loaded waveguides, respectively, with α 2 decreasing with increasing wavelength. The free-carrier absorption cross section was also estimated from the nonlinear transmittance data to be around 2.2 × 10 − 16 c m 2 for all three geometries. Our results contribute to a better understanding of the nonlinear absorption in heterostructure waveguides of different cross-sectional geometries. We discuss how the electric field distribution in the different layers of a heterostructure can lead to geometry-dependent effective two-photon absorption coefficients. More specifically, we pinpoint the third-order nonlinear confinement factor as a design parameter to estimate the strength of the effective nonlinear absorption, in addition to tailoring the bandgap energy by varying the material composition.

Evaluation of thin films intermixing by photoacoustic spectroscopy

In this paper, we show the usefulness of photoacoustic spectroscopy (PAS) to monitor the intermixing at the thin films heterojunction. CdTe/CdS bilayers with different thicknesses were used to analyze the effect of S-Te interdiffusion on the PAS spectra. Unlike the spectrum measured by the optical transmittance technique, the photoacoustic spectrum shows an optical absorption band, in addition to the absorption edge corresponding to the CdTe layer. The position of the band changes from 2.31 to 1.93 eV depending on the CdTe layer thickness in the structure. The band shifts were associated with the composition of the ternary CdS1-xTex alloy at the interface. Our interpretation of the results was supported by the PAS-Phase-Resolved and the X-Ray photoelectron spectroscopy techniques.

Experimental and theoretical studies of the structural, vibrational and optical properties of a new hybrid material (C5H6N2Cl)2 SiF6

Hybrid materials have attracted more attention to research merging the characteristics of both organic and inorganic components. The titled compound belongs to this large family of hybrid materials. It has been prepared by slow evaporation at room temperature and its structure was elucidated using single-crystal X-ray diffraction. in the monoclinic system of the P21/c centrosymmetric space group. The asymmetric unit consists of one half [SiF6]2− octahedron anion of Ci symmetry and one (C5H6N2Cl) + organic cation. The Hirshfeld surface analysis reveals important data of the intermolecular interactions presented in the crystal structure. Infrared absorption and Raman scattering spectroscopy techniques proved the presence of organic cation and the hexafluorosilicate [SiF6]2− anion. The optical properties were examined by UV-Vis-NIR absorption and transmittance techniques. Theoretical calculations based on the DFT and TDDFT theories were performed to examine over-all properties of the title compound. The obtained theoretical results were discussed and those are in good agreement with the experimental results.

Toward single-shot characterization of nonlinear optical refraction, absorption, and scattering of turbid media

Disordered media are often susceptible to optical damage even at low irradiation doses, since the corresponding microscopic structure may suffer from processes such as bleaching, chemical reactions, or morphological changes. The disorder often introduces linear and nonlinear (NL) light scattering, and currently it is a challenge to perform single-shot characterization of NL refraction, NL absorption, and NL scattering using the more common NL transmittance techniques. This work discusses how the scattered light imaging method and $\mathrm{D}4\ensuremath{\sigma}$ techniques can be combined to characterize the NL optical constants of thick turbid media. Therefore, it should help researchers aiming to draw a detailed physical picture of turbid samples at the single laser shot level.

P‐148: Investigation of photoluminescence and birefringence of nanoparticles dispersed nematic liquid crystal and its application towards liquid crystal display and optoelectronic devices

In the present investigation nanoparticles (NPs) have been dispersed into the pure nematic liquid crystal (NLC). NPs have been dispersed into the NLC with two different concentrations. Polarizing optical microscope (POD imnages have been recorded for pure NLC and NP dispersed system in the planar aligned liquid crystal cell. The dispersion of NPs in NLC increases the photoluminescence intensity which is an important finding of this study. Birefringence has also been measured here with the help of transmittance technique and it has been observed that the birefringence got increased after the dispersion of NPs into pure NLC. This is the key finding of the present reported work. Relative electric permittivity has also been measured here and found to be increased for the dispersed system as compared to the pure NLC. It is suggested that the output of the present work may be very useful in liquid crystal display and photonic applications.

Investigation of electro-optical and dielectric properties of nematic liquid crystal dispersed with biowaste based porous carbon nanoparticles: Increased birefringence for display applications

Porous carbon nanoparticles (PCNPs) of diameter 80–100 nm are obtained from teakwood materials waste, using catalyst free pyrolysis method. These PCNPs are dispersed in a pure nematic liquid crystal (NLC) with different concentrations. Polarizing optical microscopic (POM) textures are recorded for pure NLC and NLC - PCNP composites showed better homogeneous alignment when nanoparticles were dispersed in the composites as compared with the pure NLC. The birefringence measurement using the transmittance technique showed interesting properties. It is found that birefringence is increased for the NLC - PCNP composites when compared to pure NLC. Contrast ratio for the NLC - PCNP composites increased after the dispersion of PCNPs. The Relative permittivity increases for NLC - PCNP composites in comparison with the pure NLC. Dielectric measurements showed that the dielectric anisotropy increases for NLC - PCNP composites when compare to pure NLC. The electro-optical study revealed that the threshold voltage of the system decreases after the dispersion of PCNPs. Presented data of the nano composite mixtures found to be very useful in flat panel displays (FPDs) and phase shutters.

Microwave Transmittance Technique Using Microstrip Patch Antennas, as a Non-Invasive Tool to Determine Soil Moisture in Rhizoboxes.

Investigating the growth behavior of plant root systems as a function of soil water is considered an important information for the study of root physiology. A non-invasive tool based on electromagnetic wave transmittance in the microwave frequency range, operating close to 4.8 GHz, was developed using microstrip patch antennas to determine the volumetric moisture of soil in rhizoboxes. Antennas were placed on both sides of the rhizobox and, using a vector network analyzer, measured the S parameters. The dispersion parameter S21 (dB) was also used to show the effect of different soil types and temperature on the measurement. In addition, system sensitivity, reproducibility and repeatability were evaluated. The quantitative results of the soil moisture, measured in rhizoboxes, presented in this paper, demonstrate that the microwave technique using microstrip patch antennas is a reliable, non-invasive and accurate system, and has shown potentially promising applications for measurement of rhizobox-based root phenotyping.

Nondestructive detection of maturity of watermelon by spectral characteristic using NIR diffuse transmittance technique

This study demonstrated a spectral characteristic analysis method used in the maturity detection of watermelon, which was based on the visible and near-infrared spectroscopy (Vis/NIR) technology. We found that with the gradually physiological maturity of watermelon, for the diffuse transmittance spectra, the intensity of peak1 (around 720–740 nm) decreased and peak2 (around 802–805 nm) increased, and the intensity of peak1 was always higher than peak2 for immature watermelon, on the contrary, the intensity of peak1 was always lower than peak2 for mature watermelon. We proposed two spectral characteristic analysis methods that one was using the ratio of the intensity between peak1 and peak2 (RPP), the other one was using normalized difference intensity of peak (NDIP) to determine maturity stage (immature, mid-mature, mature and over-mature). And a correction factor based on the boundary value is used in RPP and NDIP to improve the classification ability. The discriminate performances of these two methods were compared through the performance of least-squares support vector machines (LS-SVM). The result indicated the Corrected-RPP (C-RPP) method showed the best predictive ability with 88.1% of correct classification rate. This is a new finding that the maturation of watermelon can be tested directly from the spectra. It has a great potential to be developed to study other fruits and be applied in portable instrument and on-line high-speed watermelons internal quality detection system based on spectroscopy database.

Validation of tissue optical properties measurement using diffuse reflectance spectroscopy (DRS).

The effectiveness of photodynamic treatment depends on several factors including an accurate knowledge of optical properties of the tissue to be treated. Transmittance and diffuse reflectance spectroscopic techniques are commonly used to determine tissue optical properties. Although transmittance spectroscopy technique is accurate in determining tissue optical properties, it is only valid in an infinite medium and can only be used for interstitial measurements. Diffuse reflectance spectroscopy, on the other hand, is easily adapted to most tissue geometries including skin measurements that involve semi-infinte medium. However, the accuracy of the measured optical properties can be affected by uncertainty in the measurements themselves and/or due to the uncertainty in the fitting algorithm. In this study, we evaluate the accuracy of optical properties determination using diffuse reflectance spectroscopy implemented using a contact probe setup. We characterized the error of the optical properties fitted using two fitting algorithms, a wavelength wise fitting algorithm and a full reflectance spectral fitting algorithm. By conducting systematic investigation of the measurements and fitting algorithm of DRS, we gained an understanding of the uncertainties in the measured optical properties and outlined improvement measures to minimize these errors.

An N-Heterocyclic Carbene Based Silver Precursor for Plasma-Enhanced Spatial Atomic Layer Deposition of Silver Thin Films at Atmospheric Pressure.

A new N-heterocyclic carbene (NHC)-based silver amide compound, 1,3-di-tert-butyl-imidazolin-2-ylidene silver(I) 1,1,1-trimethyl-N-(trimethylsilyl)silanaminide [(NHC)Ag(hmds)] was synthesized and analyzed by single-crystal X-ray diffraction, 1 H and 13 C NMR spectroscopy, as well as EI mass spectrometry, and subsequently evaluated for its thermal characteristics. This new halogen- and phosphine-free Ag atomic layer deposition (ALD) precursor was tested successfully for silver thin film growth in atmospheric pressure plasma enhanced spatial (APP-ALD). High-purity conductive Ag thin films with a low sheet resistance of 0.9 Ω/sq (resistivity: 10-5 Ωcm) were deposited at 100 °C and characterized by X-ray photoelectron spectroscopy, scanning electron microscopy, optical transmittance, and Rutherford back-scattering techniques. The carbene-based Ag precursor and the new APP-ALD process are significant developments in the field of precursor chemistry as well as metal ALD processing.