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Fluid inclusions are a window into deep geological fluids, providing unique access to their nature and composition. The isotopic composition of CO2 and CH4 hosted in fluid inclusions is a powerful proxy to assess the origin and transformation of deep geological fluids, giving insights into carbon sources, fluxes, and degassing in a wide variety of geodynamic settings. Over the last 5 decades, techniques have been developed to extract fluid inclusions from their host minerals and measure their bulk composition. These techniques are often challenged by analytical artifacts including high blank levels of CO2 and CH4, fluid re-speciation, gas adsorption, and diffusion. Since these processes may alter the pristine composition of gases liberated from fluid inclusions, rigorous protocols are needed in order to evaluate the isotopic integrity of the extracted volatile species. In this study, we introduce new protocols for bulk off-line fluid inclusion extraction for the analysis of δ13C-CH4 and δ13C-CO2 using a Cavity Ring-Down Spectroscopy (CRDS) analyser (Picarro G2201-i). Two mechanical fluid extraction techniques are compared: ball milling in ZrO2 jars and sample crushing in a stainless steel sealed tube under a hydraulic press. Blanks and isotopically labelled tests with the ball milling technique suggest that rotation speed, grinding stock filling degree and filling type alter the CH4 and CO2 concentrations and isotopic compositions measured by the CRDS analyser. In contrast, the crushing technique does not generate measurable quantities of blank CH4 and CO2. The protocols presented in this study allow to extract, detect, and analyse δ13C of CH4 and CO2 for concentrations above 10 and 1,000 ppm respectively. Interlaboratory experiments allowed to replicate previously measured δ13C-CH4 values in natural fluid inclusions within 1‰ with both extraction techniques. This study highlights the potential of combining simple bulk off-line fluid inclusion extraction techniques with a CRDS analyser for δ13C analysis of CO2 and CH4 without gas separation being required. [ABSTRACT FROM AUTHOR]

• A novel system for directly measuring net photochemical ozone production rates in the atmosphere was developed. • A comparison of P(O 3) was conducted between the directly measured and calculated based on radical reactions. • The instrument was successfully deployed for the comprehensive field observation at an urban site in Yangtze River Delta (China) for 40 days. A novel system for measuring net photochemical ozone production rates in the atmosphere based on cavity ring-down spectroscopy (OPR-CRDS) was developed. The system consists of two chambers (a reaction chamber and a reference chamber) and a dual-channel O x -CRDS detector. To minimize the wall loss of O x in the chambers, the inner surfaces of both chambers are coated with Teflon film. The performance of the OPR-CRDS system was characterized. It was found that even though the photolysis frequency (J value) decreased by 10%, the decrease in the P(O 3) caused by the ultraviolet-blocking film coating was less than 3%. The two chambers had a good consistency in the mean residence time and the measurement of NO 2 and O x under the condition of no sunlight. The detection limit of the OPR-CRDS was determined to be 0.20 ppbv/hr. To further verify the accuracy of the system, the direct measurement values of the OPR-CRDS system were compared with the calculation results based on radical (OH, HO 2 , and RO 2) reactions, and a good correlation was obtained between the measured and calculated values. Finally, the developed instrument was applied to obtain the comprehensive field observations at an urban site in the Yangtze River Delta (China) for 40 days, the time series and change characteristics of the P(O 3) were obtained directly, and the good environmental adaptability and stability of the OPR-CRDS system were demonstrated. It is expected that the new instrument will be beneficial to investigations of the relationship between P(O 3) and its precursors. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract Accurate measurement of water vapor isotopes (δ18O and δ2H) is fundamental for advancing our understanding of the hydrological cycle and improving hydrological model accuracy. This study introduces an innovative calibration methodology using a controlled evaporation mixer (CEM) for determining stable isotopic ratios in atmospheric water vapor via cavity ring-down spectroscopy. The CEM technique reliably produces a stable water vapor stream, crucial for enhancing the precision and accuracy of isotopic measurements. Its rapid adaptation to changes in water vapor concentration and compatibility with different water standards enhance calibration reliability. Demonstrated reproducibility in generating water vapor across a broad concentration range from 900 to over 25,000 ppmv, coupled with a substantial reduction in memory effects, makes this approach highly effective in both laboratory and field settings. This calibration advancement greatly enhances research capabilities for continuous atmospheric water vapor analysis, providing deeper insights into hydrological processes and atmospheric dynamics.

The present study addresses advanced monitoring techniques for particles and airborne molecular contaminants (AMCs) in cleanroom environments, which are crucial for ensuring the integrity of semiconductor manufacturing processes. We focus on quantifying particle levels and a representative AMC, hydrogen chloride (HCl), having known detrimental effects on equipment longevity, product yield, and human health. We have developed a compact laser sensor based on open-path cavity ring-down spectroscopy (CRDS) using a 1742 nm near-infrared diode laser source. The sensor enables the high-sensitivity detection of HCl through absorption by the 2-0 vibrational band with an Allan deviation of 0.15 parts per billion (ppb) over 15 min. For quantifying particle number concentrations, we examine various detection methods based on statistical analyses of Mie scattering-induced ring-down time fluctuations. We find that the ring-down distributions' 3rd and 4th standard moments allow particle detection at densities as low as ~105 m−3 (diameter > 1 μm). These findings provide a basis for the future development of compact cleanroom monitoring instrumentation for wafer-level monitoring for both AMC and particles, including mobile platforms. [ABSTRACT FROM AUTHOR]

Antibody-drug conjugates (ADCs) are a class of biopharmaceuticals that combine the specificity of monoclonal antibodies (mAbs) with the cytotoxicity of small molecule drugs. 15 ADCs have been approved by regulatory authorities up to now, mainly for indications in oncology, however, this review paper will only focus on the 13 ADCs that have been approved by either the FDA or EMA. ADME (Absorption, Distribution, Metabolism, and Excretion) studies are essential for the development of small molecule drugs to evaluate their disposition properties. These studies help to select drug candidates, determine the optimal dosing regimen and help to identify potential safety concerns for the drug of interest in human. Tissue distribution studies are also important as they facilitate the understanding of the efficacy and safety for parent drug and its metabolites in preclinical and clinical studies. For biologics, ADME studies are usually not required. In this paper, we review the existing approval packages and literature for approved ADCs to determine the extent of ADME studies performed as part of ADC registration packages. We conclude that ADME studies are recommended for the development of ADCs if new linkers and payloads are used that have never been used in humans before as these studies provide valuable information on the pharmacokinetic properties, optimal dosing regimen, and potential safety concerns. However, for the development of ADCs with established linker payload combinations, radiolabelled ADME studies may not be necessary if the distribution, metabolism and excretion properties have been described before. Clinical radiolabelled ADME studies are not recommended where patients are treated for life threating diseases like for indications in oncology. [ABSTRACT FROM AUTHOR]

Accurate measurement of water vapor isotopes (δ18O and δ2H) is fundamental for advancing our understanding of the hydrological cycle and improving hydrological model accuracy. This study introduces an innovative calibration methodology using a controlled evaporation mixer (CEM) for determining stable isotopic ratios in atmospheric water vapor via cavity ring-down spectroscopy. The CEM technique reliably produces a stable water vapor stream, crucial for enhancing the precision and accuracy of isotopic measurements. Its rapid adaptation to changes in water vapor concentration and compatibility with different water standards enhance calibration reliability. Demonstrated reproducibility in generating water vapor across a broad concentration range from 900 to over 25,000 ppmv, coupled with a substantial reduction in memory effects, makes this approach highly effective in both laboratory and field settings. This calibration advancement greatly enhances research capabilities for continuous atmospheric water vapor analysis, providing deeper insights into hydrological processes and atmospheric dynamics. [ABSTRACT FROM AUTHOR]

Fluid inclusions are a window into deep geological fluids, providing unique access to their nature and composition. The isotopic composition of CO2 and CH4 hosted in fluid inclusions is a powerful proxy to assess the origin and transformation of deep geological fluids, giving insights into carbon sources, fluxes, and degassing in a wide variety of geodynamic settings. Over the last 5 decades, techniques have been developed to extract fluid inclusions from their host minerals and measure their bulk composition. These techniques are often challenged by analytical artifacts including high blank levels of CO2 and CH4, fluid re-speciation, gas adsorption, and diffusion. Since these processes may alter the pristine composition of gases liberated from fluid inclusions, rigorous protocols are needed in order to evaluate the isotopic integrity of the extracted volatile species. In this study, we introduce new protocols for bulk off-line fluid inclusion extraction for the analysis of δ13C-CH4 and δ13C-CO2 using a Cavity Ring-Down Spectroscopy (CRDS) analyser (Picarro G2201-i). Two mechanical fluid extraction techniques are compared: ball milling in ZrO2 jars and sample crushing in a stainless steel sealed tube under a hydraulic press. Blanks and isotopically labelled tests with the ball milling technique suggest that rotation speed, grinding stock filling degree and filling type alter the CH4 and CO2 concentrations and isotopic compositions measured by the CRDS analyser. In contrast, the crushing technique does not generate measurable quantities of blank CH4 and CO2. The protocols presented in this study allow to extract, detect, and analyse δ13C of CH4 and CO2 for concentrations above 10 and 1,000 ppm respectively. Interlaboratory experiments allowed to replicate previously measured δ13C-CH4 values in natural fluid inclusions within 1‰ with both extraction techniques. This study highlights the potential of combining simple bulk off-line fluid inclusion extraction techniques with a CRDS analyser for δ13C analysis of CO2 and CH4 without gas separation being required.

Water stable isotopologue analysis is widely used to disentangle ecohydrological processes. Yet, there are increasing reports of measurement uncertainties for established and emerging methods, such as cryogenic vacuum extraction (CVE) or cavity ring‐down spectroscopy (CRDS). With this study, we investigate two pitfalls, that potentially contribute to uncertainties in water‐stable isotopologue research. To investigate fractionation sources in CVE, we extracted pure water of known isotopic composition with cotton, glass wool or without cover and compared the isotopologue results with non‐extracted reference samples. To characterise the dependency of δ2H and δ18O on the water mixing ratio in CRDS, which is of high importance for in‐situ applications with large natural variations in mixing ratios, we chose samples with a large range of isotopic compositions and determined δ2H and δ18O for different water mixing ratios with two CRDS analysers (Picarro, Inc.). Cotton wool had a strong fractionation effect on δ2H values, which increased with more 2H‐enriched samples. δ2H and δ18O values showed a strong dependency on the water mixing ratio analysed with CRDS with differences of up to 34.5‰ (δ2H) and 3.9‰ (δ18O) for the same sample at different mixing ratios. CVE and CRDS, now routinely applied in water stable isotopologue research, come with pitfalls, namely fractionation effects of cover materials and water mixing ratio dependencies of δ2H and δ18O, which can lead to erroneous isotopologue results and thus, invalid conclusions about (ecohydrological) processes. These practical issues identified here should be reported and addressed adequately in water‐stable isotopologue research. [ABSTRACT FROM AUTHOR]

We have applied cavity ring-down spectroscopy (CRDS) to the study of the 166Er isotope in an atomic beam. These measurements were realized with an external cavity diode laser tuned to the 400.9 nm atomic transition of erbium and a customized high-finesse ring-down optical cavity under vacuum. Erbium atomic beams of different number densities were generated in a tantalum foil micro-crucible within the cavity. Absorbance values of the 166Er isotope between 3 × 10−6 and 7 × 10−5 were measured with a best-case precision on the order of 10−6, which is remarkable when considering the extreme temperatures at which the measurements were conducted, and the short detection path which is characteristic of collimated atomic beams. Number densities of erbium atoms were inferred to be between 2 × 106 and 6 × 107 cm−3. This work demonstrates for the first time the ability of studying dilute atomic beams of refractory materials with high accuracy utilizing CRDS. In these initial studies, we used erbium as a model system, but we expect to extend the proposed approach to the measurement of isotopes of uranium and plutonium for nuclear non-proliferation applications. [ABSTRACT FROM AUTHOR]

Emissions from agriculture are a worldwide problem as it is the major anthropogenic source of ammonia, methane, and nitrous oxide. Several efforts have been made to mitigate emissions. To achieve this, reliable measuring techniques are necessary to quantify the impact of the emissions. Different techniques relying on different principles are available. Generally, these techniques demonstrate good agreement on their measurements but there is a lack of studies that thoroughly investigate cross-interferences. In this work, three different models of Cavity Ring-Down Spectrometers measuring ammonia, nitrous oxide, and methane were tested in parallel for potential biases due to interference from ammonia, water vapor, and twelve volatile organic compounds commonly present in agricultural environments. Our results showed a small negative bias with increasing humidity on nitrous oxide and minor interferences of ammonia on nitrous oxide and methane. None of the tested volatile organic compounds interfered with ammonia, methane, or nitrous oxide measurements. Overall, concentration measurements of ammonia, nitrous oxide, and methane with cavity ring-down spectrometry have proven reliable under typical agricultural conditions. Minor interferences were only observed under exceptional conditions.

Background: Chronic respiratory diseases (CRDs) pose a significant global health burden. Antioxidant-rich diets have been associated with improved lung health, but the specific relationship with CRDs remains unclear. Methods: This study examined the relationship between dietary antioxidant intakes and CRDs using data from the 2001–2018 National Health and Nutrition Examination Survey (NHANES). Information on dietary antioxidant intakes, including vitamins A, C, and E, zinc, selenium, and carotenoid, were collected from the 2 24-h recall interviews to calculate composite dietary antioxidant index (CDAI). CRDs were determined based on self-reported physician diagnoses. To examine the relationship between CDAI and CRDs, multivariate logistic regression was used. To study potential non-linear correlations within these associations, restricted cubic spline (RCS) regression was performed. Results: The study involved 40 557 individuals. The median CDAI was −0.09 (−2.05, 2.25). We discovered those who were in the fourth quartile of CDAI scores had a 19% lower prevalence than those in the first quartile (OR = 0.81 [0.72–0.91], Ptrend < 0.01) after adjusting for all relevant covariates. The fourth quartile of CDAI was linked with a lower prevalence of emphysema (OR = 0.57 [0.40–0.81], Ptrend < 0.01) and chronic bronchitis (OR = 0.74 [0.62–0.88], Ptrend < 0.01). RCS regression showed that CDAI was non-linearly related to the prevalence of CRDs, with inflection points of 3.20 (P for non-linearity

The isotopic composition of xylem water (δX) is of considerable interest for plant source water studies. In‐situ monitored isotopic composition of transpired water (δT) could provide a nondestructive proxy for δX‐values. Using flow‐through leaf chambers, we monitored 2‐hourly δT‐dynamics in two tropical plant species, one canopy‐forming tree and one understory herbaceous species. In an enclosed rainforest (Biosphere 2), we observed δT‐dynamics in response to an experimental severe drought, followed by a 2H deep‐water pulse applied belowground before starting regular rain. We also sampled branches to obtain δX‐values from cryogenic vacuum extraction (CVE). Daily flux‐weighted δ18OT‐values were a good proxy for δ18OX‐values under well‐watered and drought conditions that matched the rainforest's water source. Transpiration‐derived δ18OX‐values were mostly lower than CVE‐derived values. Transpiration‐derived δ2HX‐values were relatively high compared to source water and consistently higher than CVE‐derived values during drought. Tracing the 2H deep‐water pulse in real‐time showed distinct water uptake and transport responses: a fast and strong contribution of deep water to canopy tree transpiration contrasting with a slow and limited contribution to understory species transpiration. Thus, the in‐situ transpiration method is a promising tool to capture rapid dynamics in plant water uptake and use by both woody and nonwoody species. Summary Statement: Tracing the isotopic composition of transpiration (δT) in real‐time showed rapid dynamics in plant water uptake and use by woody and nonwoody species. Daily δ18OT‐values weighted by the transpiration flux are a good proxy for δ18O of xylem water. [ABSTRACT FROM AUTHOR]

Triangular cavities are increasingly used in cavity ring-down spectrometers (CRDS) to compensate for the existence of optical feedback and other disadvantages of straight cavities. However, at the same time, the difficulty of the cavity mounting alignment process is increased. Consequently, the fast and stable establishment of resonance between the optical source and the triangular ring-down cavity has been widely explored for CRDS-based applications. The Hermite-Gaussian theory has unique advantages for the description of the Gaussian resonant beams characteristics in triangular cavities, while the theory is of great importance for the alignment in high finesse triangular ring-down cavities. Along these lines, in this work, the eigenfrequency separation characteristics of the Hermite-Gaussian modes in the triangular cavity, in the meridional and sagittal planes, as well as the excitation and transmission characteristics of the first-order mode in the high finesse cavity were verified. A static alignment method was established for the high-finesse triangular ring-down cavity, and the transmission suppression of the Hermite-Gaussian modes by the high-finesse cavity was overcome in the experiment. Finally, by leveraging the advantageous features of the fundamental and the first-order mode that are complementary to each other, the tilt and axis shift errors of each specified plane with directional high accuracy can be aligned. The static alignment scheme of the triangular cavity based on the Hermite-Gaussian theory that was established here paves the way for the mounting alignment of the CRDS instrument before the ring-down experiment, whereas the system accuracy of CRDS is further improved.

Triangular planar ring resonant cavities are widely used in cavity ring-down spectroscopes (CRDS) because of the unique optical path advantage. Hermite-Gaussian theory is the classical method used to describe the beam in the resonant cavity. Since this theory can express the transverse electromagnetic mode (TEM) in the meridian plane and sagittal surface separately in an astigmatic triangular cavity, it has a unique advantage in the analysis of triangular cavities. However, among the many analyses of triangular ring-down cavities, existing theories of Hermite-Gaussian modes have not been able to reasonably explain the many phenomena observed in alignment and ring-down experiments. In this paper, the mechanisms of the effects of first-order Hermite-Gaussian mode on mounting alignment in CRDS instruments are investigated in depth. The frequency separation characteristics of the lower-order mode in the triangular cavity are verified in the mounting alignment stage. The separation characteristics of first-order mode can guide the misalignment of the two orthogonal planes separately. The resonant frequency separation property of the Hermite-Gaussian mode in a triangular ring-down cavity can also be applied to more complex odd-numbered cavity mirror resonant systems.

A sensitive, compact detector for the simultaneous measurement of O3 and NO2 is presented in this work. There are two channels in the detector, namely the Ox channel and the NO2 channel. In the presence of excess NO, ambient O3 is converted to NO2 in the Ox measurement channel. In both channels, NO2 is directly detected via cavity ring-down spectroscopy (CRDS) at 409 nm. At a 10 s integration time, the Ox and NO2 channels have a 1σ precision of 14.5 and 13.5 pptv, respectively. The Allan deviation plot shows that the optimal sensitivity of O3 and NO2 occurs at an integration time of ~60 s, with values of 10.2 and 8.5 pptv, respectively. The accuracy is 6% for the O3 channel and 5% for the NO2 channel, and the largest uncertainty comes from the effective NO2 absorption cross-section. Intercomparison of the NO2 detection between the NO2 and Ox channels shows good agreement within their uncertainties, with an absolute shift of 0.31 ppbv, a correlation coefficient of R2 = 0.99 and a slope of 0.98. Further intercomparison for ambient O3 measurement between the O3/NO2-CRDS developed in this work and a commercial UV O3 monitor also shows excellent agreement, with linear regression slopes close to unity and an R2 value of 0.99 for 1 min averaged data. The system was deployed to measure O3 and NO2 concentrations in Hefei, China, and the observation results show obvious diurnal variation characteristics. The successful deployment of the system has demonstrated that the instrument can provide a new method for retrieving fast variations in ambient O3 and NO2. [ABSTRACT FROM AUTHOR]

Triple oxygen isotope ratios have been increasingly acknowledged as useful hydrological tracers but measuring both 17O/16O and 18O/16O ratios with meaningful precision has been challenging due to the much lower natural abundance of 17O than 16O and even 18O. In this study, in line with the advancement of laser-based techniques and their growing applications, we demonstrate how to optimize the determination of 17O-excess (Δ17O = ln(δ17O + 1) − 0.528 × ln(δ18O + 1)) in natural water using a commercial wavelength-scanned cavity ring-down spectrometer (WS-CRDS). We particularly focus on how to decide the injection numbers of samples and standard solutions utilized for normalization of sample results to the VSMOW-SLAP reference scale. With a measurement strategy aimed at an uncertainty better than 10 per meg (1σ), the Δ17O of Greenland Ice Sheet Precipitation (GISP) is determined to be 24 ± 9 per meg (n = 104), in agreement with previous literature values. By applying this method to Antarctic glacial ice, it is shown to be useful in detecting the seasonality of Δ17O values in Antarctic precipitation. Our approach represents an underlying analytical method that provides guidelines for determining Δ17O from various types of natural waters. [ABSTRACT FROM AUTHOR]

Internal water in cold‐water and tropical coral skeletons was extracted and measured for its oxygen and hydrogen isotope ratios. Water was extracted by crushing pieces of coral hard tissue in a percussion device connected to either a cavity ring‐down spectroscopy (CRDS) system or an isotope ratio mass spectrometry (IRMS) system. Despite most samples yielding sufficient water, each analytical system produces distinct isotope patterns. Experiments show that several characteristics specific to biominerals give rise to discrepancies and analytical artefacts that preclude the acquisition of reproducible isotope data. The main complication is that internal water in biogenic carbonates is distributed in an open interconnected micro‐network that readily exchanges with external water and potentially facilitates interaction with hydration water in the finely dispersed organic matrix in the coral skeleton. Furthermore, only an isotopically fractionated part of the internal water is released from the coral skeletons upon crushing. Altogether, isotope ratio measurement of internal water in corals with bulk crushing techniques does not give primary fluid isotope ratios useful for (palaeo‐)environmental or microbiological studies. As the resulting isotope patterns can show systematic behaviour per technique, isotope data may be erroneously interpreted to reflect the original calcifying fluid when using only a single technique to isotopically characterise internal fluids in coral skeletons. [ABSTRACT FROM AUTHOR]

During resonance in resonant cavities, such as those used in laser or cavity ring-down spectroscopes (CRDS), resonant coupling between higher-order transverse modes and fundamental modes can seriously affect the quality of the beam and introduce measurement errors. Several coupling models, such as thermal deformation coupling and scattering coupling, have been established according to existing coupling theory and specific application scenarios; however, these coupling models have not been attributed to a unified theory. In this paper, we reveal that the same resonant coupling excitation factors exist under different types of environmental perturbation. The conditions and range of resonant coupling in a CRDS ring-down cavity are systematically analyzed, and a preferential coupling model of the middle-order modes is proposed. The time-domain characteristics of the CRDS are used in experiments to analyze the resonant coupling between the modes in a weak energy system. The order and coupling range of the middle-order modes involved in resonant coupling are verified using the modal filtering characteristics of the triangular cavity; this paper presents a unified explanation for various types of resonant coupling and also provides a new approach to resonant coupling experiments performed in high-finesse resonant cavities. [ABSTRACT FROM AUTHOR]

We present an experimental study of carbon dioxide absorption in the transparency window near 700 nm, where different calculations predicted several extremely weak bands. The measurements were done using the optical frequency comb-assisted cavity ring-down spectrometer reaching sensitivity (noise-equivalent absorption) of 3. 1 ⋅ 1 0 − 12 cm−1. None of 21 lines, predicted by the most comprehensive calculations, were detected in five separate spectral regions near 700 nm. Our estimated detection limit ranges between 3 and 21 times lower than the expected peak absorption in the conditions of the experiment. • Experimental validation of HITRAN and AMES CO 2 line lists near 700 nm. • No CO 2 absorption predicted by databases observed in the range 14300 to 14550 cm−1. • CRD spectrometer absorption detection sensitivity 3.1 ⋅ 10−12 cm−1. [ABSTRACT FROM AUTHOR]

Chronic respiratory diseases (CRDs), including pulmonary fibrosis, chronic obstructive pulmonary disease (COPD), lung cancer, and asthma, are significant global health problems due to their prevalence and rising incidence. The roles of protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs) in controlling tyrosine phosphorylation of targeting proteins modulate multiple physiological cellular responses and contribute to the pathogenesis of CRDs. Src homology‐2 domain‐containing PTP2 (SHP2) plays a pivotal role in modulating downstream growth factor receptor signaling and cytoplasmic PTKs, including MAPK/ERK, PI3K/AKT, and JAK/STAT pathways, to regulate cell survival and proliferation. In addition, SHP2 mutation and activation are commonly implicated in tumorigenesis. However, little is known about SHP2 in chronic pulmonary inflammation and fibrosis. This review discusses the potential involvement of SHP2 deregulation in chronic pulmonary inflammation and fibrosis, as well as the therapeutic effects of targeting SHP2 in CRDs. [ABSTRACT FROM AUTHOR]

Optical feedback cavity ringdown spectroscopy is presented with a linear Fabry–Pérot cavity and a cost-effective DFB laser. To circumvent the low coupling efficiency caused by the broad laser linewidth, an optical feedback technique is used, and an enhanced coupling efficiency of 31%, mainly limited by impedance mismatch and mode mismatch, is obtained. The trigger of the ringdown event is realized by the shutoff of the laser driving current, and a novel method with the aid of one electronic switch is applied to avoid the ringdown events excited by the unexpected cavity modes during the process of laser current recovery. As a result, the ringdown signal with a signal-to-noise ratio of 2500 is achieved. Through continuous monitoring, the fractional uncertainty of the empty cavity ringdown times is assessed to be 0.04%. An Allan variance analysis indicates a detection sensitivity of 4.3 × 10−10 cm−1 is resulted at an integration time of 120 s, even with a moderate finesse cavity. To further improve the long-term stability, we regularly rectify the empty cavity ringdown time, and an improvement factor of 2.5 is demonstrated.

Summary: This study investigated the carbon isotope ratio (¹³C/¹²C, δ13C in unit of parts per thousand or per mill, ‰) of different coconut water samples using elemental analysis isotope ratio mass spectrometry (EA‐IRMS) and combustion module cavity ring‐down spectroscopy (CM‐CRDS). Natural coconut water from young coconuts from 12 provinces in Thailand (n = 94), adulterated coconut water containing three sweeteners (sucrose, glucose and fructose) at different concentrations and eight brands of commercial coconut water were analysed. The δ13C of all samples were not significantly different (P > 0.05) between the EA‐IRMS and CM‐CRDS analyses. The natural coconut water (C3 plant) had δ13C ranging from −21.58‰ to −27.79‰ (mean −24.64 ± 0.91‰). Three sweeteners (C4 plant) contained δ13C between −11.46‰ to −13.16‰. The use of δ13C determination can detect adulteration of a singular extraneous sweetener (either glucose or sucrose) down to a level of 2% of adulteration. For the detected δ13C values of commercial products labelled as 'no added sugar', about 50% of products were adulterated. This study demonstrates that CM‐CRDS can be used as an alternative analytical platform to EA‐IRMS for detecting adulterated products, especially coconut water. [ABSTRACT FROM AUTHOR]

A sensitive, compact detector for the simultaneous measurement of O3 and NO2 is presented in this work. There are two channels in the detector, namely the Ox channel and the NO2 channel. In the presence of excess NO, ambient O3 is converted to NO2 in the Ox measurement channel. In both channels, NO2 is directly detected via cavity ring-down spectroscopy (CRDS) at 409 nm. At a 10 s integration time, the Ox and NO2 channels have a 1σ precision of 14.5 and 13.5 pptv, respectively. The Allan deviation plot shows that the optimal sensitivity of O3 and NO2 occurs at an integration time of ~60 s, with values of 10.2 and 8.5 pptv, respectively. The accuracy is 6% for the O3 channel and 5% for the NO2 channel, and the largest uncertainty comes from the effective NO2 absorption cross-section. Intercomparison of the NO2 detection between the NO2 and Ox channels shows good agreement within their uncertainties, with an absolute shift of 0.31 ppbv, a correlation coefficient of R2 = 0.99 and a slope of 0.98. Further intercomparison for ambient O3 measurement between the O3/NO2-CRDS developed in this work and a commercial UV O3 monitor also shows excellent agreement, with linear regression slopes close to unity and an R2 value of 0.99 for 1 min averaged data. The system was deployed to measure O3 and NO2 concentrations in Hefei, China, and the observation results show obvious diurnal variation characteristics. The successful deployment of the system has demonstrated that the instrument can provide a new method for retrieving fast variations in ambient O3 and NO2.

During resonance in resonant cavities, such as those used in laser or cavity ring-down spectroscopes (CRDS), resonant coupling between higher-order transverse modes and fundamental modes can seriously affect the quality of the beam and introduce measurement errors. Several coupling models, such as thermal deformation coupling and scattering coupling, have been established according to existing coupling theory and specific application scenarios; however, these coupling models have not been attributed to a unified theory. In this paper, we reveal that the same resonant coupling excitation factors exist under different types of environmental perturbation. The conditions and range of resonant coupling in a CRDS ring-down cavity are systematically analyzed, and a preferential coupling model of the middle-order modes is proposed. The time-domain characteristics of the CRDS are used in experiments to analyze the resonant coupling between the modes in a weak energy system. The order and coupling range of the middle-order modes involved in resonant coupling are verified using the modal filtering characteristics of the triangular cavity; this paper presents a unified explanation for various types of resonant coupling and also provides a new approach to resonant coupling experiments performed in high-finesse resonant cavities.

High precision and fast measurement of gas concentrations is important for both understanding and monitoring various phenomena, from industrial and environmental to medical and scientific applications. This article deals with the recent progress in ammonia detection using in-situ solid-state and optical methods. Due to the continuous progress in material engineering and optoelectronic technologies, these methods are among the most perceptive because of their advantages in a specific application. We present the basics of each technique, their performance limits, and the possibility of further development. The practical implementations of representative examples are described in detail. Finally, we present a performance comparison of selected practical application, accumulating data reported over the preceding decade, and conclude from this comparison. [ABSTRACT FROM AUTHOR]

Zusammenfassung Das Integrated Carbon Observation System (ICOS) ist eine auf mindestens 20 Jahre ausgelegte europäische Forschungsinfrastruktur. Fertig ausgebaut, sollen mehr als 130 über Europa verteilte Stationen hochpräzise und zeitlich hochaufgelöste Treibhausgasmessungen bereitstellen. Ermöglicht wird dies zum einen durch extrem empfindliche Messtechniken, zum Beispiel Laserspektroskopie, zum anderen durch eine hohe Standardisierung der Messsysteme, der Erfassung und Auswertung der Daten sowie einer strengen Qualitätskontrolle und Qualitätssicherung. Basierend auf ICOS‐Daten und mit geeigneten Inversionsmodellen sollen Veränderungen bei den Treibhausgasflüssen in Deutschland verfolgt werden. Damit wird der Erfolg von Maßnahmen zur Emissionsminderung von Treibhausgasen verifizierbar. [ABSTRACT FROM AUTHOR]

• An optical feedback cavity ring down spectrometer (OF-CRDS) is developed at 8.45 µm. • Water self-continuum cross-sections at 1185 cm−1 are measured between 296 and 308 K. • Our cross-section value is found about 20% smaller than the MT_CKD_4.1 value. • Available measurements in the 10 µm window seem to indicate that the MT_CKD_4.1 temperature dependence is overestimated. The accurate knowledge of the water vapor absorption in the 10 µm atmospheric window is of strong importance because this spectral range coincides with the maximum black body emission of Earth. Presently, the water vapor self-continuum is measured at the 1185 cm−1 (8.45 µm) spectral point, located in the most transparent interval of the 10 µm window. Measurements are performed at four temperatures ranging from 296 to 308 K using a newly developed Optical Feedback Cavity Ring Down Spectrometer (OF-CRDS). Self-continuum cross-sections, C S , are derived from the pressure dependence of the absorption during pressure ramps of pure water vapor up to 18 mbar. From the quadratic pressure dependence observed for the absorption coefficient at each temperature, we derived the value of the cross-section (C S = 0.996 (12) × 10 − 22 cm 2 molecule−1atm−1 at 296 K) and its temperature dependence. These results are discussed in relation with previous literature measurements available in the 10 µm window. Our cross-section is found about 20% smaller than the MT_CKD_4.1 value and the available experimental works seem to indicate that the MT_CKD_4.1 temperature dependence is overestimated. [Display omitted] [ABSTRACT FROM AUTHOR]

• First demonstration of the detection of small amounts of methane at 8.014 µm. • Achieving the lowest detection limit of 0.063 ppb after an averaging time of 28.1 s. • Providing 1.9 times better selectivity than the frequently chosen absorption line at 7.67 µm. • Development of an OPO-DFG-based CRDS setup ensuring spectral measurements at various pressures. The paper describes the first demonstration of the detection of small amounts of methane using the 8.014 µm absorption line and cavity ring-down spectroscopy (CRDS) employing an optical parametric oscillator equipped with a differential frequency generator. The study confirmed the high stability of the system to pressure changes and the lowest detection limit of 0.063 ppb for an averaging time of 28.1 s. Experimental verification of methane spectra using a high-resolution vacuum FTIR spectrometer, tests of the developed setup presenting the influence of the wavelength resolution on the spectrum, and determining the detection limit using Alan's deviation were performed. Analysis of the achievable selectivity of methane sensors in individual water windows indicated in the range of 7.5–8.3 µm, taking into account the absorption bands of gases occurring in the standard atmosphere according to the HITRAN 2008 database was also described. Furthermore, the work presents an analysis of available solutions in the field of methane sensing, particularly on the range of longer infrared wavelengths, which showed a small number of described studies in the long wavelength infrared (LWIR) range and constituted a reference for the evaluation of the obtained result. [ABSTRACT FROM AUTHOR]

Background: Chronic respiratory diseases (CRDs) pose a significant global health burden. Antioxidant-rich diets have been associated with improved lung health, but the specific relationship with CRDs remains unclear., Methods: This study examined the relationship between dietary antioxidant intakes and CRDs using data from the 2001-2018 National Health and Nutrition Examination Survey (NHANES). Information on dietary antioxidant intakes, including vitamins A, C, and E, zinc, selenium, and carotenoid, were collected from the 2 24-h recall interviews to calculate composite dietary antioxidant index (CDAI). CRDs were determined based on self-reported physician diagnoses. To examine the relationship between CDAI and CRDs, multivariate logistic regression was used. To study potential non-linear correlations within these associations, restricted cubic spline (RCS) regression was performed., Results: The study involved 40 557 individuals. The median CDAI was -0.09 (-2.05, 2.25). We discovered those who were in the fourth quartile of CDAI scores had a 19% lower prevalence than those in the first quartile (OR = 0.81 [0.72-0.91], P trend < 0.01) after adjusting for all relevant covariates. The fourth quartile of CDAI was linked with a lower prevalence of emphysema (OR = 0.57 [0.40-0.81], P < 0.01). RCS regression showed that CDAI was non-linearly related to the prevalence of CRDs, with inflection points of 3.20 ( trend < 0.01) and chronic bronchitis (OR = 0.74 [0.62-0.88], P trend < 0.01). RCS regression showed that CDAI was non-linearly related to the prevalence of CRDs, with inflection points of 3.20 ( P for non-linearity <0.01). The stratified analysis did not identify variables that significantly affected the results., Conclusion: Higher dietary antioxidant intakes were related with a lower prevalence of CRDs (particularly emphysema and chronic bronchitis) in general adults., Competing Interests: The authors have no competing interests to declare., (© 2023 The Authors.)

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• High sensitivity absorption spectrum of acetylene is recorded by CRDS near 1.73 µm. • The number of assigned lines are 2620 and 250 for 12C 2 H 2 and 12C13CH 2 , respectively. • The assigned 12C 2 H 2 lines belong to 53 bands which are mostly newly reported. • Spectroscopic parameters and Herman–Wallis coefficients are derived. • A recommended empirical line list is provided for each band. The high-resolution absorption spectrum of acetylene has been recorded at room temperature by high sensitivity cavity ring down spectroscopy (CRDS) in the 5693–5882 cm–1 region. The noise level of the recordings corresponds to a typical minimum detectable absorption, α min , below 10-10 cm−1. The positions and intensities of about 4000 lines were determined and analyzed together with about 3900 lines left unassigned in a previous CRDS study in the 5850–6340 cm−1 region. In total, about 2620 12C 2 H 2 and 250 12C13CH 2 absorption lines are assigned in the present work, most of them being newly reported. The 12C 2 H 2 lines belong to 53 bands and include 24 bands newly identified or improved in the region of the previous study. Altogether, 107 bands in the entire 5693–6340 cm−1 while the HITRAN database provides line parameters of only nine 12C 2 H 2 bands in the same region. The lines of 12C13CH 2 in normal abundance (2.2%) belong to eight bands whose intensities are reported for the first time. Spectroscopic parameters of the upper vibrational levels were derived from standard band-by-band fits of the line positions (typical rms values of the (obs.-calc.) deviations are better than 0.002 cm–1). The vibrational transition dipole moment squared and Herman–Wallis coefficients of each band were derived from a fit of the measured intensity values. A recommended line list is provided for the bands newly assigned with positions calculated using empirical spectroscopic parameters of the lower and upper energy vibrational levels and intensities computed using the derived Herman–Wallis coefficients. As a result, the constructed line list includes a total of 4471 transitions belonging to 53 bands of 12C 2 H 2 and 8 bands of 12C13CH 2. This list of acetylene transitions above 5693 cm−1 extends to lower energy and completes our empirical spectroscopic database for acetylene in the 5850–9415 cm−1 range. Image, graphical abstract [ABSTRACT FROM AUTHOR]

• High sensitivity CRDS of CO 2 enriched in 17O in the 1.74 µm transparency window. • About 1100 transitions assigned to 26 bands of the six 17O isotopologues of CO 2. • Very weak lines with intensity value of about 2 × 10−29 cm/molecule are detected. • Spectroscopic parameters of the upper vibrational levels are determined from a band-by-band fit. The room temperature absorption spectrum of 17O enriched carbon dioxide is investigated by high sensitivity cavity ring down spectroscopy (CRDS) between 5695 and 5850 cm−1. About 1100 lines are measured and assigned to 26 bands of the six 17O containing carbon dioxide isotopologues: 16O12C17O, 16O13C17O, 17O12C18O, 17O13C18O, 12C17O 2 and 13C17O 2. The set of observed lines are rovibrationnally assigned on the basis of the predictions of the effective Hamiltonian (EH) model. The observed bands belong to the ΔP = 8 and 9 series of transitions where P = 2 V 1 + V 2 + 3 V 3 is the polyad number (V i being the vibrational quantum numbers). They consist in 12 previously unobserved bands and 14 already-known bands, for which additional high J lines are assigned. Bands of the 12C17O 2 and 13C17O 2 isotopologues (two for each) are observed for the first time in this spectral interval. The spectroscopic parameters of the upper vibrational levels are determined from a band-by-band fit of the line positions (typical rms deviations are less than 0.001 cm−1). The comparison to the most recent carbon dioxide spectroscopic databases is presented. The reported data will be used to improve the modeling of the line positions of 17O containing carbon dioxide isotopologues. [ABSTRACT FROM AUTHOR]

• Detailed analysis of the ν 1 + 3ν 3 band of 14N16O 2 near 1.66 µm. • More than 3000 lines are assigned with N and K a up to 59 and 13, respectively. • Line positions are reproduced by an effective Hamiltonian with an rms of 0.0023 cm−1. • The (103) upper level is perturbed by the (122), (410) and (080) "dark" states. • The main effective dipole moment parameter is determined. The high resolution absorption spectrum of the NO 2 molecule is recorded between 5855 and 6006 cm−1 by high sensitivity cavity ring down spectroscopy (CRDS). Positions and intensities in the 5 × 10−27 − 4 × 10−23 cm/molecule range are derived from the profile fitting of more than 6900 lines. The absorption is dominated by the transitions of the (103)–(000) vibrational band centered at 5984.704 cm−1. The spectrum is assigned and modeled using an effective Hamiltonian (EH) which explicitly takes into account a spin–rotational interaction and interaction of the (103) bright state with three "dark" states: (122), (080) and (410). The ν 1 + 3ν 3 band was already analyzed by Fourier transform spectroscopy (FTS) in Miljanic S., Perrin A., Orphal J., Fellows C.E., Chélin, J. Mol. Spectrosc. 2008, V. 251, P. 9–15, where resonance interactions between the (103) state and the (122) and (080) "dark" states were taken into account. More than 3000 lines are presently assigned with rotational quantum numbers N and K a up to 59 and 13, respectively, while 1147 transitions with maximum N and K a values of 47 and 8, respectively, were previously identified by FTS. The measured line positions are reproduced with an (obs.-calc.) rms of 0.0023 cm−1 by variation of 41 EH parameters. About 80 transitions reaching the (080) highly excited bending upper state and borrowing their intensity from the resonance coupling with the (103)–(000) band were assigned for the first time. The main parameter in the transition moment series of the ν 1 + 3ν 3 band is determined from the fitting of the measured intensities. Image, graphical abstract [ABSTRACT FROM AUTHOR]

• High sensitivity cavity ring down spectroscopy of N 2 O between 5696 and 5910 cm−1. • 3326 lines assigned to 50 bands of five N 2 O isotopologues in natural abundance. • 26 of the 31 bands of the main isotopologue, 14N 2 16O, are newly reported. • The spectroscopic parameters of the upper levels are derived from a band-by-band fit. • Intra- and inter-polyad perturbations identified for a number of bands. In spite of being a greenhouse gas with a large global warming potential, the absorption spectrum of nitrous oxide in the near infrared is insufficiently characterized. In the present work, the spectral region near 1.74 µm (5696–5910 cm−1) is investigated by high sensitivity cavity ring down spectroscopy (CRDS). The noise level of the CRDS spectra corresponds to a typical minimum detectable absorption, α min , below 10-10 cm−1. 3326 transitions are measured and rovibrationally assigned to 50 bands of five nitrous oxide isotopologues (14N 2 16O, 14N15N16O, 15N14N16O, 14N 2 18O and 14N 2 17O) in natural isotopic abundance. The assigned weakest lines have an intensity below 10−28 cm/molecule. For comparison, only three 14N 2 16O bands are included in the HITRAN database in the region, with a 2 × 10−25 cm/molecule intensity cut off. The rovibrational assignments were performed by comparison with predictions performed for each isotopologue in the frame of the effective operator approach. The overall quality of the predictions is satisfactory for line positions. Deviations larger than 0.1 cm−1 are nevertheless noted for 14N 2 16O and 14N 2 18O. The spectroscopic parameters of the upper level of the observed bands were derived from the standard band-by-band fit of the measured line positions. A significant number of bands were found to be perturbed by local rovibrational perturbations and in some cases, extra lines due to an intensity transfer could be assigned. The interaction mechanisms and the perturbers were univocally identified on the basis of the effective Hamiltonian model. In particular, interpolyad couplings were evidenced indicating that the polyad version of the effective Hamiltonian has to be extended to include Coriolis and interpolyad anharmonic interactions. No satisfactory modeling of the N 2 O line intensities is yet available in the region. The CRDS intensity values derived in this work provide a solid set of measurements for future semi-empirical intensity modeling in the region. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Highlights • Water self-continuum cross-sections are measured by CRDS in the 1.6 µm window. • These accurate measurements confirm and extend a previous CRDS study. • Self-continuum cross-sections are also measured near 4720 cm−1 and 5130 cm−1. • Foreign-continuum cross-sections are reported at 4 points of the 2.3 µm window. • Significant underestimations of the MT_CKD foreign continuum are evidenced. Abstract New measurements of the water vapour continuum in the 1.6 µm and 2.3 µm windows are obtained at room temperature using highly stable and sensitive cavity ring down (CRD) spectrometers. In the 1.6 µm window, self-continuum cross-sections, C S , are derived for 30 selected spectral points between 5700 and 6850 cm−1 using pressure ramps of pure water vapour (up to 15 Torr). Purely quadratic pressure dependence is obtained for each measurement point. Compared to our previous dataset (Mondelain et al., 2014), the retrieved C s values are more accurate and show a general agreement. The spectral coverage is extended both on the high and low frequency edges of the 1.6 µm window. In addition, new C S values are derived in the 5120–5137 cm−1 interval extending to higher energy the coverage of the 2.3 µm window. The measurements near 5700 cm−1 and 5130 cm−1 are found lower than the MT_CKD_3.2 values by a factor of about 2 and 1.5, respectively. Foreign-continuum cross-sections, C F , are newly obtained in the 2.3 µm window from CRDS spectra of moist air in flow regime. Spectra were recorded for different water vapour partial pressures while maintaining the total pressure constant in the high finesse CRDS cavity. After subtraction of the monomer and self-continuum contributions, C F values were derived from the linear variation of the foreign-continuum absorption with the water vapour partial pressure. C F values determined at four spectral points between 4430 and 5000 cm−1 are larger by up a factor of five than the corresponding MT_CKD values. Considering these CRDS data at room temperature and literature values at 400 K the temperature dependence of the foreign-continuum is confirmed to be weak. Graphical abstract Image, graphical abstract [ABSTRACT FROM AUTHOR]

Abstract NH is a key short-lived radical involved in the prompt-NO formation. Quantification of NH is thus particularly important for testing the NO kinetic mechanisms. However, quantitative measurements of native NH in hydrocarbon/oxygen/nitrogen flames remain very scarce. Therefore, in this work, the mole fractions of native NH were obtained using a combination of laser-based diagnostics; Laser Induced Fluorescence (LIF) and Cavity Ring-Down Spectroscopy (CRDS). The NH species was probed after exciting the transition R 1 (6) in the A3Π-X3Σ− (0-0) system at 333.9 nm. The mole fraction profiles of NH were successfully obtained in premixed low-pressure flames of CH 4 /O 2 /N 2 and C 2 H 2 /O 2 /N 2 at two equivalence ratios of 1.00 and 1.25. The estimated detection limit for the NH radical was around 4.5 × 108 molecule cm−3 (i.e. 2 ppb in mole fraction at 1600 K), which is nearly 2 orders of magnitude lower than previous values reported in the literature. These new experimental results were compared with predictions by a recently developed NO model (namely NOMecha2.0). In the case of the CH 4 flames, a satisfying agreement between the experiment and model was observed. However, in the case of the C 2 H 2 flames, some discrepancies were observed. Model analysis has highlighted the importance of the HCCO radicals in the NH formation through the HCNO→HNCO→NH 2 reactions pathway. Modification of the rate constant values of the reactions C 2 H 2 + O and HCCO + O 2 , which are key reactions for both the acetylene laminar flame speed and the HCCO predictions, has enabled the model to satisfactorily predict the experimental NH and NO profiles also in the C 2 H 2 flames. [ABSTRACT FROM AUTHOR]

Abstract Processes on both synoptic scale and mesoscale contribute to variations in the atmospheric water vapor isotopic signal in the lower troposphere. The drivers of the isotopic composition of water vapor at these temporal scales is a key topic of discussion. The aim of this paper is to decouple mesoscale from synoptic processes that affect the water vapor isotopic composition over a coastal lagoon and to quantify the vertical mixing and sea breeze contributions to the daily water vapor cycle. We monitored the water vapor isotopic composition at the beginning of the 2017 spring season for 21 days, at the inland boundary of the Venetian Lagoon (Italy) with a commercially available cavity ring-down spectroscopy analyzer. Mean atmospheric pressure fields and back trajectories are used to investigate the long-range transport of water vapor to the study area. Moisture source areas and d-excess correlation maps show that the control on the d-excess parameter is dominated by the mesoscale contribution. The daily cycle of water vapor is studied in detail, showing that the intrusion of air from the free atmosphere represents the main process that occurs in the morning. Under those circumstances, the morning variability of the water vapor isotopic composition can be used as a proxy for the Planetary Boundary Layer height. The study period was characterized by a constant development of the sea breeze circulation that conserved the marine signature of water vapor until the afternoon. However, the water vapor isotopic signal tends to stabilize when atmospheric conditions such as high relative humidity and a weak gradient in the atmospheric pressure field occur, leading to the establishment of an isotopic equilibrium between the atmospheric water vapor and surface waters. Highlights • Synoptic and mesoscale processes highlighted by the water vapor isotopic composition. • Trend of water vapor isotopic signal related to SLP field at the regional scale. • Daily depletion of water vapor isotopes strongly related to PBL height. • Sea breeze imprints a clear pattern to water vapor d-excess. • Daily component of isotopic signal dominated by entrainment and mixing. [ABSTRACT FROM AUTHOR]

Background: The Nature Step to Respiratory Health was the overarching theme of the 12th General Meeting of the Global Alliance against Chronic Respiratory Diseases (GARD) in Helsinki, August 2018. New approaches are needed to improve respiratory health and reduce premature mortality of chronic diseases by 30% till 2030 (UN Sustainable Development Goals, SDGs). Planetary health is defined as the health of human civilization and the state of the natural systems on which it depends. Planetary health and human health are interconnected, and both need to be considered by individuals and governments while addressing several SDGs. Results: The concept of the Nature Step has evolved from innovative research indicating, how changed lifestyle in urban surroundings reduces contact with biodiverse environments, impoverishes microbiota, affects immune regulation and increases risk of NCDs. The Nature Step calls for strengthening connections to nature. Physical activity in natural environments should be promoted, use of fresh vegetables, fruits and water increased, and consumption of sugary drinks, tobacco and alcohol restricted. Nature relatedness should be part of everyday life and especially emphasized in the care of children and the elderly. Taking "nature" to modern cities in a controlled way is possible but a challenge for urban planning, nature conservation, housing, traffic arrangements, energy production, and importantly for supplying and distributing food. Actions against the well‐known respiratory risk factors, air pollution and smoking, should be taken simultaneously. Conclusions: In Finland and elsewhere in Europe, successful programmes have been implemented to reduce the burden of respiratory disorders and other NCDs. Unhealthy behaviour can be changed by well‐coordinated actions involving all stakeholders. The growing public health concern caused by NCDs in urban surroundings cannot be solved by health care alone; a multidisciplinary approach is mandatory. [ABSTRACT FROM AUTHOR]

The absorption spectra of trace water vapor in N 2 gas with a mole fraction of 500 nmol/mol in the pressure range of 20 kPa to 140 kPa were obtained near 7181 cm−1 using wavelength-meter-controlled cavity ring-down spectroscopy (WMC-CRDS). The reference gas (water vapor in N 2 gas) was produced using a generation system of primary measurement standards for trace moisture in gases, where the amount of water vapor was measured using a gravimetric method. The obtained spectra of H 2 O were analyzed using a multispectrum fitting technique with a speed-dependent asymmetric Voigt profile (SDAVP). The values of the line intensity were determined with traceability to the International System of Units (SI). We could achieve the expanded uncertainty below 2 % for the line intensities of the strong lines. • The absorption spectra of H 2 O were recorded near 7181 cm−1 using wavelength-meter-controlled CRDS. • As a reference, the primary measurement standard for trace moisture in N 2 gas was used. • The line-shape parameters were determined by a multispectrum fitting technique with an SDAVP. • The value of line intensity was determined with SI traceability. [ABSTRACT FROM AUTHOR]

High precision and fast measurement of gas concentrations is important for both understanding and monitoring various phenomena, from industrial and environmental to medical and scientific applications. This article deals with the recent progress in ammonia detection using in-situ solid-state and optical methods. Due to the continuous progress in material engineering and optoelectronic technologies, these methods are among the most perceptive because of their advantages in a specific application. We present the basics of each technique, their performance limits, and the possibility of further development. The practical implementations of representative examples are described in detail. Finally, we present a performance comparison of selected practical application, accumulating data reported over the preceding decade, and conclude from this comparison.

A concept of a highly sensitive and fast-response airborne optoelectronic hygrometer, based on the absorption spectroscopy with laser light tuned to an intense ro-vibronic absorption line of H2O in the 1391- 1393 nm range is presented. The target application of this study is airborne atmospheric measurements, in particular at the top of troposphere and in stratosphere. The cavity ring-down spectroscopy was used to achieve high sensitivity. In order to avoid interference of the results by water desorbed from the instrument walls, the open-path solution was applied. Tests of the instrument, performed in a climatic chamber, have shown some advantages of this concept over typical hygrometers designed for similar applications. [ABSTRACT FROM AUTHOR]

Klotho is an anti-aging protein that is engaged in the suppression of canonical WNT signaling. In this study, we investigated the expression pattern of human WNTs and Klotho in the pancreatic cancer. In the cancerous cells, WNT-1 exhibited much higher expression as compared to other WNTs, while no WNT expression was detected in the normal tissue. In contrast, Klotho expression was significantly low in the cancerous tissue. Based on these observations, we intended to explore Klotho binding to WNT-1 and cystein-rich domains (CRDs) of Frizzled (FZD) homologs through molecular docking and dynamics simulation assays. Interestingly, similar region of WNT-1 was detected in binding with Klotho and CRDs of FZD-1/2. FZD-CRDs were grasped by the association of peripheral hydrophobic residues of WNT-1 U-shaped cavity. Subsequently, WNT-1-bound Klotho-peptides were isolated and reevaluated for their binding abilities against WNT-1 and FZD-CRDs., The conformational readjustements of these complexes were deeply analyzed by calculating the size of WNT-1 U-shaped cavity. In comparison to apo-WNT-1, cavity opening was markedly enhanced (8.2 Å to 15.64 Å, 32.89 Å and 35.11 Å) in WNT-1-a, WNT-1-c and WNT-1-e complexes, respectively. Thus Klotho-derived peptides may facilitate distinct conformational changes in the WNT-1-FZD associated region. As a result, aberrant loss of FZD binding may lead to augment WNT signaling. Overall, current study opens up new avenues in the pancreatic cancer therapeutics through antagonizing WNT-1 by Klotho. [ABSTRACT FROM AUTHOR]