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Obesity is a disease of epidemic proportions with a concerning increasing trend. Regarded as one of the main sources of energy, lipids can also represent a big part of an unnecessary intake of calories and be, therefore, directly related to the problem of obesity. Pancreatic lipase is an enzyme that is essential in the absorption and digestion of dietary fats and has been explored as an alternative for the reduction of fat absorption and consequent weigh loss. Literature describes a great variability of methodologies and experimental conditions used in research to evaluate the in vitro inhibitory activity of compounds against pancreatic lipase. However, in an attempt to choose the best approach, it is necessary to know all the reaction conditions and understand how these can affect the enzymatic assay. The objective of this review is to understand and summarize the methodologies and respective experimental conditions that are mainly used to evaluate pancreatic lipase catalytic activity. 156 studies were included in this work and a detailed description of the most commonly used UV/Vis spectrophotometric and fluorimetric instrumental techniques are presented, including a discussion regarding the differences found in the parameters used in both techniques, namely enzyme, substrate, buffer solutions, kinetics conditions, temperature and pH. This works shows that both UV/Vis spectrophotometry and fluorimetry are useful instrumental techniques for the evaluation of pancreatic lipase catalytic activity, presenting several advantages and limitations, which make the choice of parameters and experimental conditions a crucial decision to obtain the most reliable results. [ABSTRACT FROM AUTHOR]

This study was meticulously conducted, delving into the epitaxial growth of nanothin β-In2Se3 films on sapphire (0001) using molecular beam epitaxy. The growth temperature was carefully set at 480 °C, and the selenium to indium flux ratio (RSe/In) was systematically varied from 1 to 100. The phase transformation from γ-In2Se3 to β-In2Se3 was precisely controlled by manipulating the RSe/In and confirmed through Raman scattering measurements and synchrotron-based grazing-incidence wide-angle X-ray scattering. The surface morphology for various RSe/In of In2Se3 was analyzed by atomic force microscopy (AFM). The lowest surface roughness is around 0.58 nm, which is achieved under the RSe/In = 60 growth condition. The nanothin β-In2Se3 film with a layer-by-layer atomic arrangement was verified by high-resolution transmission electron microscopy. According to the experimental results, the growth dynamics of In2Se3 are proposed to be step-flow growth and horizontal growth under RSe/In 45 and 60 conditions, respectively. This research underscores the control of the growth mechanism by Se/In flux and its role in facilitating the In2Se3 epitaxy for integration in the development of 2D-materials-based future electronic devices. [ABSTRACT FROM AUTHOR]

The article investigates the effect of atmospheric water vapor on the results of noncontact temperature measurements carried out in the range from 100 to 600 °C. It is known that the key disadvantage of radiation thermometry is a rather strong dependence of the measurement results on external factors: the state of the surface of the object, as well as the state of the environment for the propagation of radiation from the object to the thermometer. Water vapor constantly present in the atmosphere selectively absorbs the infrared radiation of the object, which leads to underestimation of the results. This effect depends on the humidity and temperature of the air, as well as on the distance between the object and the radiation thermometer. On the basis of the simulation performed using the MATLAB system and the HITRAN molecular spectroscopy database, the values of random and systematic errors are calculated for four measurement situations typical of industrial conditions that differ in the level of absorption by water vapor. Eleven variants of radiation receivers with unique spectral sensitivity characteristics are studied. It is shown that the effect of absorption of the infrared radiation of an object by water vapor can lead to a significant decrease in the reliability of measurements carried out even at short distances.

Wireless power transfer has become a research hotspot in the field of energy transmission, among which laser energy transfer is one of the best approaches for long‐distance wireless transmission. Based on good atmospheric transmittance, especially the wavelengths consistent with the response range of mainstream Si and GaAs photovoltaic cells with relatively high photoelectric efficiency, diode‐pumped alkali laser (DPAL) energy transfer will have huge prospects. To solve the problem of long‐distance laser energy transfer of DPALs, laser atmospheric molecular absorption was calculated by analyzing the atmospheric transmission absorption effects of laser beams with specific wavelengths. The atmospheric transmission of three typical alkalis at different atmospheric modes and altitudes was calculated and compared, and practical suggestions were given. [ABSTRACT FROM AUTHOR]

We present a machine learning framework for modeling the absorption properties of azobenzene molecules – an important class of organic compounds with many potential photochemical applications. The framework utilizes predictors based on the chemical composition and structure of each molecule and consists of separate regression models trained to predict the absorption at distinct wavelengths, covering the UV and visible light ranges. Despite the relatively small size of the dataset (330 molecule-absorption spectrum pairs), the models were able to learn to accurately predict the absorption at fixed wavelengths, as well as the position and intensity of the maximum absorption. These predictions can be used to rapidly screen thousands of candidate molecules for a variety of potential applications, reducing the need for time-consuming and expensive experiments or first-principles computations.

This paper provides a comprehensive framework to analyze the performance of non-orthogonal multiple access (NOMA) in the downlink transmission of a single-carrier and multi-carrier terahertz (THz) network. Specifically, we first develop a novel user pairing scheme for the THz-NOMA network which ensures the performance gains of NOMA over orthogonal multiple access (OMA) for each individual user in the NOMA pair and adapts according to the molecular absorption. Then, we characterize novel outage probability expressions considering a single-carrier and multi-carrier THz-NOMA network in the presence of various user pairing schemes, Nakagami- $m$ channel fading, and molecular absorption noise. We propose a moment-generating-function (MGF) based approach to analyze the outage probability of users in a multi-carrier THz network. Furthermore, for negligible thermal noise, we provide simplified single-integral expressions to compute the outage probability in a multi-carrier network. Numerical results demonstrate the performance of the proposed user-pairing scheme and validate the accuracy of the derived expressions. [ABSTRACT FROM AUTHOR]

The determination of nonmetals via molecular absorption spectrometry (MAS) began in the 1970s using conventional atomic absorption spectrometry with a line source. However, due to low resolution and spectral interferences, these measurements were improved by the development of the high-resolution continuum source that provides information about the spectral environment. Hence, here is reviewed formative studies on the determination of nonmetals as well as the state of the art of this approach. This review presents the fundamentals of the MAS involving the determination of S, P, Cl, F, and Br, and the cutting-edge research such as isotopic determination via MAS. [ABSTRACT FROM AUTHOR]

Brown Carbon (BrC) absorbs light in wavelength of 300–400 nm, and BrC molecule (BrCM) is a fundamental component responsible for aerosol radiative forcing. In this study, Fourier‐transform ion cyclotron resonance mass spectrometry (FT‐ICR MS) coupled with electrospray ionization (ESI) was used to determine methanol extracted BrCM in PM2.5 collected in Xi'an, China. The absorption of individual BrCM was quantified through partial least square regression (PLSR) method. Results showed that 77.5% and 91.8% of winter and summer BrCMs were weak absorptive. The top BrCMs were responsible for 60.4% and 84.6%, respectively, of the absorbances in summer and winter. The nitrogen (N)‐containing organic molecules were identified to be critical components of light‐absorbing matters in both of the two seasons, outlining the significance of N chromogenesis in BrC. The top BrCMs were more closely related to ‐(O)NO2 that originated from NO2 engaged reactions in winter, and to ‐NH that formed in NH3 reactions in summer. Sulfur (S)‐containing functional groups were not chromophoric while sulfur dioxide (SO2) triggered N‐containing and S‐free BrCM formations under high nitrogen oxides (NOx) concentration levels and relative humidity (RH) in winter. Hypochromicity of oxygen (O) in BrC was discovered because of the photobleaching of oxidation and weak light‐absorbing of highly oxidized molecules. Key Points: Nitrogen is a critical chromogenic element in brown carbon moleculeThe sulfur‐containing functional group is not chromogenic, but SO2 can stimulate the formation of secondary brown carbonOxygen bleaches brown carbon molecules [ABSTRACT FROM AUTHOR]

The Terahertz (THz) band is envisioned as a promising technique to support bandwidth-hungry and secure applications. Although the significant path loss and strong directivity make THz communications secure naturally, the information security is still imperfect at near regions along the beam propagation path. In this paper, a novel distance-adaptive absorption peak modulation (DA-APM) is developed for THz covert communications, by exploring the unique spectrum features of frequency-dependent molecular absorption. Although high-attenuation molecular absorption is unfavored for communications, the main principle to enhance covertness or equivalently, minimize the eavesdroppable distance, is dynamically modulating signals under the molecular absorption peaks in the THz spectrum, where the eavesdroppable distance is defined as the threshold distance within which an eavesdropper can wiretap the transmission. Furthermore, an optimization framework is proposed to minimize the eavesdroppable distance, to which the sub-optimal solutions are derived for the multi-wideband waveform by controlling carrier frequencies, power allocation, and rate distribution on each sub-band. Extensive numerical results show that the THz-spectrum-based DA-APM approach can reduce the eavesdroppable distance by 60% compared with random spectrum selection methods, which significantly reduce the insecure area and enhance the covertness of THz wireless transmission. [ABSTRACT FROM AUTHOR]

Theoretically calculated research studies of oxygen absorption on gold cluster surface were used to simulate chemical reactions on the surfaces of gold nanoparticles. Low-energy conformational structures of tetra-nuclear gold cluster complexes with multiple oxygen molecule ligands, Au4(O2)n+ (n = 1∼4), were theoretically investigated by the DFT calculations with long-range-corrected hybridisation functional CAM-B3LYP. In addition to known low-energy structures with tetragonal four-gold core, new low-energy isomers with Y-shaped four-gold core were revealed to be stable. The rationality of new structures was confirmed by the agreement of calculated infrared vibrational spectra with experimental results. The findings of new structures successfully interpreted the features of the vibrational spectra of this series of clusters. Highlights: New low-energy complex structures, containing a Y-shaped four-gold core, are stabilised by absorption of oxygen molecules and possess large first dissociation energy of oxygen molecule. The O–O stretching fundamental frequency of the Au–O–O–Au tetragon in the complexes with the Y-shaped four-gold core is found to be the origin of experimental vibrational absorption at about 1250 cm−1. Sum frequency of the stretching vibrations of the Au–O bond and the O–O bond is responsible for absorption observed at 1470 cm−1. A new activation mode of oxygen molecule is found in the Au–O–O–Au tetragon of new Y-core complexes, where the O-O bond length is ca. 1.30 angstrom (normally, ca. 1.20 angstrom). [ABSTRACT FROM AUTHOR]

Based on the spectral observations of Jupiter carried out over recent years, we consider the behavior of weak molecular absorption bands of methane and ammonia in a wavelength range of 600−800 nm. In the latitudinal behavior of the intensity of these bands, rather clearly expressed features, demonstrating a connection with the zonal structure of cloud belts of the planet, are traced. However, for different bands, the positions of the absorption extrema in latitude somewhat differ. The changes in the zonal spectra show the weakening in absorption observed toward the disk edge, which is most probably connected with the radiative transfer geometry in an optically active layer of the atmosphere. The importance of studying the weak absorption bands is stressed, since precisely these bands make it possible to analyze the structural features and their variations in the troposphere of Jupiter. When interpreting the observational data, it is necessary to consider at least two alternative models for forming the absorption bands. One of them should deal with an optically thick layer of ammonia clouds, where the multiple scattering on particles in this layer plays the main part in producing the molecular absorption bands. The second model should be based on the assumption of a small optical thickness of the ammonia cloud layer, according to which the absorption is mainly formed under clouds, where the scattering on a pure gaseous component is weak. [ABSTRACT FROM AUTHOR]

In this paper, we show how the absorption and re-radiation energy from molecules in the air can influence the Multiple Input Multiple Output (MIMO) performance in high-frequency bands, e.g., millimeter wave (mmWave) and terahertz. In more detail, some common atmosphere molecules, such as oxygen and water, can absorb and re-radiate energy in their natural resonance frequencies, such as 60 GHz, 180 GHz and 320 GHz. Hence, when hit by electromagnetic waves, molecules will get excited and absorb energy, which leads to an extra path loss and is known as molecular attenuation. Meanwhile, the absorbed energy will be re-radiated towards a random direction with a random phase. These re-radiated waves also interfere with the signal transmission. Although, the molecular re-radiation was mostly considered as noise in literature, recent works show that it is correlated to the main signal and can be viewed as a composition of multiple delayed or scattered signals. Such a phenomenon can provide non-line-of-sight (NLoS) paths in an environment that lacks scatterers, which increases spatial multiplexing and thus greatly enhances the performance of MIMO systems. Therefore in this paper, we explore the scattering model and noise models of molecular re-radiation to characterize the channel transfer function of the NLoS channels created by atmosphere molecules. Our simulation results show that the re-radiation can increase MIMO capacity up to 3 folds in mmWave and 6 folds in terahertz for a set of realistic transmit power, distance, and antenna numbers. We also show that in the high SNR, the re-radiation makes the open-loop precoding viable, which is an alternative to beamforming to avoid beam alignment sensitivity in high mobility applications. [ABSTRACT FROM AUTHOR]

Hydrogen has become a strong candidate to be a future energy storage medium but there are technological challenges both in its production and storage. For storage, a search for lightweight, abundant and non-toxic materials is on the way. An abundant natural material such as wood cellulose would make an ideal storage medium from a sustainability perspective. Here, using a combination of static DFT calculations and ab initio molecular dynamics simulations at different temperatures, it is shown that wood cellulose has the ability to uptake H 2 via a physisorption mechanism based on dispersion interactions of the van der Waals type involving the O-atoms of the d -glucose rings. The absorption causes little to no disturbances on the cellulose structure and H 2 is highly mobile in the material. At an external pressure of H 2 (g) of 0.09 atm and T = 25 °C, cellulose has a theoretical gravimetric density of hydrogen storage of ≈1%. • Wood cellulose as a hydrogen storage material. • Molecular hydrogen absorption – physisorption. • Room temperature absorption-desorption. [ABSTRACT FROM AUTHOR]

Knowledge of the molecular‐level chemistry of brown carbon (BrC) is important in reducing the uncertainties in aerosol radiative forcing. Time‐resolved ambient PM2.5 samples were collected during a severe pollution episode in January 2017 over Xi'an, China for a comprehensive nontarget and full scanning of BrC molecules and their absorption properties using electrospray ionization Fourier transform–ion cyclotron resonance mass spectrometry combined with partial least squares regression analysis, which apportioned the overall ultraviolet absorption to individual molecules. The estimated absorption of CHNO and CHNOS molecules exhibited nighttime prevalence, whereas CHOS, CHNS, CHN, CHO, CHS, and CH molecules presented a dynamic trend. Carbon conjugation was positively correlated with estimated absorption by CHO and CHNO molecules, while exhibiting a mixed relationship with CHNOS. Higher nitrogen content was associated with enhanced light‐absorption properties of BrC molecules, while higher oxygen and sulfur content appeared to be associated with photobleaching during secondary transformation. Plain Language Summary: Individual molecular absorption has significant implications for ambient brown carbon analysis, but existing studies mostly focused on bulk absorption properties for the sample as a whole. A novel method is presented here to evaluate individual brown carbon absorption at the molecular level through high resolution mass spectrometry, and partial least squares regression analysis was applied to PM2.5 samples collected during a heavy pollution episode in Xi'an, China. Nitrogen‐containing compounds were found to be the strongest contributor to brown carbon absorption, especially during the nighttime, while processes involving oxidation and sulfur addition appeared to weaken the molecular absorption. This study bridges the gap between real atmospheric PM2.5 absorption and knowledge from controlled laboratory studies, which support these findings. Key Points: The molecular absorption of CHNOS and CHNO exhibited significant diurnal variationConjugation and elevated N content were associated with BrC photo‐enhancementOxidation and elevated S content appeared to be associated with light photobleaching of BrC molecules [ABSTRACT FROM AUTHOR]

Natural hydrates are a form of the gas existence in depths and a promising source of hydrocarbon gas. Manmade hydrates in bottom-hole zones and wellbores complicate hydrocarbon production, reducing production rates. In oil and gas collection systems hydrates are deposited under certain conditions of temperature and pressure on the walls of the pipes and increase its hydraulic resistance, thereby increasing energy consumption. The presence of hydrates in streams of producing fluid increases the wear of prefabricated collectors, reducing their life. In hydrocarbon field preparation`s systems (heat exchange equipment, separators, throttle devices, ejectors) hydrate deposition degrades technological processes. Hydrate formation in machinery and equipment (compressor, expander) collection and treatment systems lead to accidents. In gas pipeline transport the hydrate deposition reduces its effectiveness. To solve problems associated with technogenic hydrates and gas production from natural hydrates, it is necessary to know the basic features of their formation. The article contains modern concepts of single- and multi-component gashydrates formation (natural and oil), which occur in natural and technical systems. Authors hope that the paper will be useful to a wide range of readers, especially students and staff of higher education institutions of oil and gas profile, as well as professionals, industrial activity of whom is connected with production, collection, preparation and transportation of natural and oil gases. Based on the systematization and analysis of more than a thousand experimental research and practical applications in this area over the period since 1780 to the present time, the authors have identified some features of the hydrate formation from single or multi-component gases.

The impact of SEOM–IAS (Scientific Exploitation of Operational Missions–Improved Atmospheric Spectroscopy) spectroscopic information on CO columns from TROPOMI (Tropospheric Monitoring Instrument) shortwave infrared (SWIR) observations was examined. HITRAN 2016 (High Resolution Transmission) and GEISA 2015 (Gestion et Etude des Informations Spectroscopiques Atmosphériques 2015) were used as a reference upon which the spectral fitting residuals, retrieval errors and inferred quantities were assessed. It was found that SEOM–IAS significantly improves the quality of the CO retrieval by reducing the residuals to TROPOMI observations. The magnitude of the impact is dependent on the climatological region and spectroscopic reference used. The difference in the CO columns was found to be rather small, although discrepancies reveal, for selected scenes, in particular, for observations with elevated molecular concentrations. A brief comparison to Total Column Carbon Observing Network (TCCON) and Network for the Detection of Atmospheric Composition Change (NDACC) also demonstrated that both spectroscopies cause similar columns; however, the smaller retrieval errors in the SEOM with Speed-Dependent Rautian and line-Mixing (SDRM) inferred CO turned out to be beneficial in the comparison of post-processed mole fractions with ground-based references.

High-quality observations have indicated the need for improved molecular spectroscopy for accurate atmospheric characterization. Line data provided by the new SEOM-IAS (Scientific Exploitation of Operational Missions—Improved Atmospheric Spectroscopy) database in the shortwave infrared (SWIR) region were used to retrieve CO total vertical columns from a selected set of nadir SCIAMACHY (SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY) observations. In order to assess the quality of the retrieval results, differences in the spectral fitting residuals with respect to the HITRAN 2016 (High-resolution TRANsmission molecular absorption) and GEISA 2015 (Gestion et Etude des Informations Spectroscopiques Atmosphériques) line lists were quantified and column-averaged dry-air CO mole fractions were compared to NDACC (Network for the Detection of Atmospheric Composition Change) and TCCON (Total Carbon Column Observing Network) ground-based measurements. In general, it was found that using SEOM-IAS line data with corresponding line models improve the spectral quality of the retrieval (smaller residuals) and increase the fitted CO columns, thereby reducing the bias to both ground-based networks.

This multidisciplinary paper reports on a research application-led study for predicting atmospheric attenuation, and tries to bridge the knowledge gap between applied engineering and atmospheric sciences. As a useful comparative baseline, this paper focuses specifically on atmospheric attenuation under pristine conditions, over the extended terahertz spectrum. Three well-known simulation software packages (`HITRAN on the Web', MODTRAN®4, and LBLRTM) are compared and contrasted. Techniques used for modeling atmospheric attenuation have been applied to investigate the resilience of (ultra-)wide fractional bandwidth applications to the effects of molecular absorption. Two extreme modeling scenarios are investigated: horizontal path links at sea level and Earth-space path links. It is shown by example that a basic software package (`HITRAN on the Web') can give good predictions with the former, whereas sophisticated simulation software (LBLRTM) is required for the latter. Finally, with molecular emission included, carrier-to-noise ratio fade margins can be calculated for the effects of line broadening due to changes in macroscopic atmospheric conditions with sub-1-THz ultra-narrow fractional bandwidth applications. Outdoors can be far from pristine, with additional atmospheric contributions only briefly introduced here; further discussion is beyond the scope of this paper, but relevant references have been cited.

Total fluorine concentrations in some fish species and seafood such as mussels, squid (calamary), and shrimp were determined using the molecular absorption of calcium monofluoride (CaF) generated in a graphite furnace using a high-resolution continuum source atomic absorption spectrometer and direct solid sampling. The fish fillets and seafood were dried at 110°C, minced finely, put on the platform using masses less than 1.2 mg, and introduced to the graphite furnace with 20 µg of calcium by a solid sampling accessory. The effects of CaF wavelength, graphite furnace program, amount of sample introduced to the furnace, the use of modifier on the determination of fluorine were investigated and optimized. The absolute limit of detection and characteristic mass of the method were 0.28 and 0.14 ng of fluorine, respectively. By applying the optimized parameters, the concentrations of fluorine in various fish species and seafood were determined. [ABSTRACT FROM AUTHOR]

Based on the material of long-term spectrophotometric observations of Jupiter, we studied the weak absorption bands of ammonia at 645 and 878 nm, whose behavior had previously been little studied. A clearly expressed depression of ammonia absorption in the 787-nm band was found in the Northern Equatorial Belt (NEB) of Jupiter. In the Great Red Spot, this band also exhibits substantial weakening. The position of the depression in the NEB is similar to that of the enhanced brightness temperature detected in the observations of the millimeter-wave radio emission, which is considered to be a result of the reduced ammonia content in this belt. At the same time, the weakening of the 787-nm band in the Red Spot is most likely caused by the enhanced bulk density of clouds, which influences the formation of absorption bands in the multiple scattering by cloud particles. The brightness temperature in the Red Spot is relatively low, as seen from observations in the radio and thermal IR ranges. We studied the spatial and temporal variations of the 645- and 787-nm bands in five belts of Jupiter: the Equatorial Zone (EZ), both Equatorial Belts (SEB and NEB), and both Tropical Zones (STZ and NTZ). The observations covered the time interval from 2005 to 2015, i.e., almost a complete orbital period of Jupiter. These observations confirmed the systematic character of the depression of the 787-nm band in the NEB and the difference in the latitudinal variations of the 645- and 787-nm bands. The latter can be related to features of the vertical distribution of the cloud density, which has a different influence on bands of different intensity. [ABSTRACT FROM AUTHOR]

Radiation is a key process in the atmosphere. Numerous radiative transfer codes have been developed spanning a large range of wavelengths, complexities, speeds, and accuracies. In the infrared and microwave, line-by-line codes are crucial esp. for modeling and analyzing high-resolution spectroscopic observations. Here we present Py4CAtS—PYthon scripts for Computational ATmospheric Spectroscopy, a Python re-implemen-tation of the Fortran Generic Atmospheric Radiation Line-by-line Code GARLIC, where computationally-intensive code sections use the Numeric/Scientific Python modules for highly optimized array processing. The individual steps of an infrared or microwave radiative transfer computation are implemented in separate scripts (and corresponding functions) to extract lines of relevant molecules in the spectral range of interest, to compute line-by-line cross sections for given pressure(s) and temperature(s), to combine cross sections to absorption coefficients and optical depths, and to integrate along the line-of-sight to transmission and radiance/intensity. Py4CAtS can be used in three ways: in the (Unix/Windows/Mac) console/terminal, inside the (I)Python interpreter, or Jupyter notebook. The basic design of the package, numerical and computational aspects relevant for optimization, and a sketch of the typical workflow are presented. In conclusion, Py4CAtS provides a versatile environment for “interactive” (and batch) line-by-line radiative transfer modeling.

This paper describes the contents of the 2016 edition of the HITRAN molecular spectroscopic compilation. The new edition replaces the previous HITRAN edition of 2012 and its updates during the intervening years. The HITRAN molecular absorption compilation is composed of five major components: the traditional line-by-line spectroscopic parameters required for high-resolution radiative-transfer codes, infrared absorption cross-sections for molecules not yet amenable to representation in a line-by-line form, collision-induced absorption data, aerosol indices of refraction, and general tables such as partition sums that apply globally to the data. The new HITRAN is greatly extended in terms of accuracy, spectral coverage, additional absorption phenomena, added line-shape formalisms, and validity. Moreover, molecules, isotopologues, and perturbing gases have been added that address the issues of atmospheres beyond the Earth. Of considerable note, experimental IR cross-sections for almost 300 additional molecules important in different areas of atmospheric science have been added to the database. The compilation can be accessed through www.hitran.org . Most of the HITRAN data have now been cast into an underlying relational database structure that offers many advantages over the long-standing sequential text-based structure. The new structure empowers the user in many ways. It enables the incorporation of an extended set of fundamental parameters per transition, sophisticated line-shape formalisms, easy user-defined output formats, and very convenient searching, filtering, and plotting of data. A powerful application programming interface making use of structured query language (SQL) features for higher-level applications of HITRAN is also provided. [ABSTRACT FROM AUTHOR]

Boron isotope amount ratios n( 10 B)/n( 11 B) have been determined by monitoring the absorption spectrum of boron monohydride (BH) in a graphite furnace using high-resolution continuum source molecular absorption spectrometry (HR-CS-MAS). Bands (0 → 0) and (1 → 1) for the electronic transition X 1 Σ + → A 1 Π were evaluated around wavelengths 433.1 nm and 437.1 nm respectively. Clean and free of memory effect molecular spectra of BH were recorded. In order to eliminate the memory effect of boron, a combination of 2% (v/v) hydrogen gas in argon and 1% trifluoromethane in argon, an acid solution of calcium chloride and mannitol as chemical modifiers was used. Partial least square regression (PLS) for analysis of samples and reference materials were applied. For this, a spectral library with different isotopes ratios for PLS regression was built. Results obtained around the 433.1 nm and 437.1 nm spectral regions are metrologically compatible with those reported by mass spectrometric methods. Moreover, for the evaluated region of 437 nm, an accuracy of 0.15‰ is obtained as the average deviation from the isotope reference materials. Expanded uncertainties with a coverage factor of k = 2 range between 0.15 and 0.44‰. This accuracy and precision are compatible with those obtained by mass spectrometry for boron isotope ratio measurements. [ABSTRACT FROM AUTHOR]

For the purpose of finding suitable molecules applicable to sulfur determination and to compare their analytical sensitivity systematically, high-resolution overview molecular absorption spectra of sulfides of group 14 elements produced in a graphite furnace were investigated. To that end a modular simultaneous echelle spectrograph (MOSES) was used, which allows recording sub-ranges of spectra out of a total wavelength range from 190 nm to 735 nm. The combined overview spectra show a complex structure with many vibrational bands, each of them consisting of a multitude of sharp rotational lines. The absorption of rotational lines of SiS (282.910 nm), GeS (295.209 nm), SnS (271.578 nm), and PbS (335.085 nm) has been analyzed for optimizing the particular experimental conditions regarding to the sulfur determination. Using the commercial CS AAS instrument contrAA 600 under optimized conditions such as the temperature program, the modification of the platform with Zr and the use of chemical modifiers, the achieved characteristic masses for sulfur are 12 ng (CS), 15.7 ng (SiS), 9.4 ng (GeS), 20 ng (SnS), and 220 ng (PbS). The first four sulfides provide an analytical sensitivity at roughly the same level, but the GeS molecule seems to be the best one with respect to analytical sensitivity and flexibility in molecular formation control. The PbS molecule provides the lowest analytical sensitivity, and together with its low bond strength it is not recommended for sulfur determination. [ABSTRACT FROM AUTHOR]

An improved design for a handheld smartphone-based spectrometer that works in both absorption and emission modes is proposed. The device, named Spectrophone, comprises modules made in MDF, an embedded light source designed for absorption mode, a DVD for the diffraction grating, and a smartphone to process the image data acquired. A user-friendly homemade software decompose the pixels from shots of spectral images into their RGB and hue (H) values which are processed by a simple algorithm developed to convert H values to their corresponding wavelengths. Analytical signals for the absorption mode are provided by an empirical equation based on RGB vector norms (||vRGB||) taken in blank and after light absorption, while ||vRGB|| is directly used to acquire emission signals. The Spectrophone was applied to determine Fe2+ in medicine samples and Na+ in saline solution and natural water samples. No statistically significant differences were observed in comparison with commercial instruments (α = 5%). The figures of merit of the Spectrophone were very good, with limits of quantification of 70 μg L-1 for absorption and 60 μg L-1 emission modes, respectively, and high linearity (R2 > 0.9995). High accuracy, simplicity, a user-friendly application and low-cost make this handheld device an attractive alternative for the absorption/emission measurements. [ABSTRACT FROM AUTHOR]

Simple experiments are proposed for measuring molecular absorption of chromate and dichromate ions using an atomic absorption spectrometer. The experiments can help undergraduate students in instrumental analysis courses understand important aspects involving conceptual and instrumental similarities and differences between frequently used analytical techniques. Hollow cathode lamps were selected with wavelengths in the region of molecular absorption of chromate and dichromate. Calibration curves were obtained and the linear dynamic range was evaluated. Results were compared with those obtained in a molecular absorption spectrometer. The molar absorptivities obtained were also compared.

This study describes the applicability of solid sampling technique for the determination of fluorine in various baby foods via molecular absorption of calcium monofluoride generated in a graphite furnace of high-resolution continuum source atomic absorption spectrometry. Fluorine was determined at CaF wavelength, 606.440 nm in a graphite tube applying a pyrolysis temperature of 1000 °C and a molecule forming temperature of 2200 °C. The limit of detection and characteristic mass of the method were 0.20 ng and 0.17 ng of fluorine, respectively. The fluorine concentrations determined in standard reference sample (bush branches and leaves) were in good agreement with the certified values. By applying the optimized parameters, the concentration of fluorine in various baby foods were determined. The fluorine concentrations were ranged from

This paper focuses on molecular absorption noise caused by molecular absorption in the higher frequency bands, such as THz band (0.1–10 THz). This transmission induced noise has been predicted to exist in the THz band, since the conservation of energy requires the conservation of the absorbed energy in the medium. There exist multiple models for the molecular absorption noise. Most of them focus only on the transformation of the absorbed energy directly into antenna temperature. This paper aims at giving additional perspectives to the molecular absorption noise. It is shown that the molecular absorption noise can be investigated with multiple different approaches, strongly affecting on the predicted strength and behavior of the noise. The full molecular absorption noise model is not given in this paper. Instead, we study the molecular absorption noise from different perspectives and give their derivations and the general ideas behind the noise modeling. [ABSTRACT FROM AUTHOR]

An analytical method for the determination of sulfur, as the tin mono-sulfide (SnS) molecule, in crude oil using high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS GF MAS) has been developed. The molecular absorbance of the SnS has been measured using the wavelength at 271.624 nm and the crude oil samples were prepared as micro-emulsions due to their high viscosity. Several chemical modifiers (Ir, Pd, Ru, Zr) were tested and palladium was chosen, because it exhibited the best performance. The heating program was optimized by comparing the pyrolysis and vaporization curves obtained for an aqueous sulfur standard and a micro-emulsion of a crude oil certified reference material (CRM). The optimum pyrolysis and vaporization temperatures were found to be 600 and 2000 °C, respectively. The limit of detection and the characteristic mass using micro-emulsion analysis of crude oil samples were 5.8 and 13.3 ng S. Accuracy and precision of the method has been evaluated using two crude oil CRM (NIST 2721 and NIST 2722), showing good agreement with the informed or certified values. [ABSTRACT FROM AUTHOR]

Molecular absorption of diphosphorus was produced in a graphite furnace and evaluated in view of its suitability for phosphorus determination. Measurements were performed with two different high-resolution continuum source absorption spectrometers. The first system is a newly in-house developed simultaneous broad-range spectrograph, which was mainly used for recording overview absorption spectra of P 2 between 193 nm and 245 nm. The region covers the main part of the C 1 Σ u + ← X 1 Σ g + electronic transition and shows a complex structure with many vibrational bands, each consisting of a multitude of sharp rotational lines. With the help of molecular data available for P 2 , an assignment of the vibrational bands was possible and the rotational structure could be compared with simulated spectra. The second system is a commercial sequential continuum source spectrometer, which was used for the basic analytical measurements. The P 2 rotational line at 204.205 nm was selected and systematically evaluated with regard to phosphorus determination. The conditions for P 2 generation were optimized and it was found that the combination of a ZrC modified graphite tube and borate as a chemical modifier were essential for a good production of P 2 . Serious interferences were found in the case of nitrate and sulfuric acid, although the nitrate interference can be eliminated by a higher pyrolysis temperature. The reliability of the method was proved by analysis of certified samples. Using standard tubes, a characteristic mass of 10 ng and a limit of detection of 7 ng were found. The values could further be improved by a factor of ten using a miniaturized tube with an internal diameter of 2 mm. Compared to the conventional method based on the phosphorus absorption line at 213.618 nm, the advantages of using P 2 are the gentle temperature conditions and the potential of performing a simultaneous multi-line evaluation to further improve the limit of detection. [ABSTRACT FROM AUTHOR]

Time and frequency domain channel models are proposed for nanonetworks utilizing the terahertz band (0.1–10 THz) for wireless communication. Nanonetworks are formed by tiny nanodevices which consist of nanoscale (molecular scale) components. Channel models capturing the unique peculiarities of the THz band are needed for designing proper physical layer techniques and for accurate performance analysis. Existing channel models have included the free space path loss and the molecular absorption loss, which is significant in the THz band. This paper theoretically analyzes scattering including multiple scattering referring to a sequence of scattering events from small particles, such as aerosols. Both the frequency and the impulse responses are derived. It is shown that the small particle scattering can result into significant additional loss that needs to be taken into account with the loss depending on the density and size distribution of the particles. It is shown that multiple scattering leads to a long tail in the impulse response. As most of the physical layer proposals for nanonetworks are based on the on-off keying, the channel response to pulse waveforms is specifically considered. [ABSTRACT FROM PUBLISHER]

• Acceleration of radiative transfer calculations suitable for general circulation modeling. • Parameterization technique is based on the k-distribution method. • The parameterizations depend only on initial photoabsorption cross-sections. • Efficiency of the parameterizations was validated with the original line-by-line Monte Carlo model. We present an effective parameterization of molecular absorption of shortwave solar radiation in Venus atmosphere. It is addressed to general circulation modeling to accelerate radiative transfer calculations in the spectral interval 125 – 400 nm (25000 – 80000 cm − 1). In F-UV and M-UV regions strong absorption of CO 2 and SO 2 enables to parameterize gaseous absorption with only three effective cross-sections. In N-UV region absorption of SO 2 and unknown UV absorber are parameterized with six effective cross-sections for each species. For treatment of Rayleigh scattering and optical properties of Venus clouds eight effective spectral points are recommended. The parameterizations were validated by the original reference line-by-line Monte-Carlo radiative transfer model. The outcome of the validation shows discrepancy in fluxes less than 3%. Thus, it takes only eight-fold solution of radiative transfer equations to correctly describe solar fluxes and heating rates in the whole ultraviolet region. [ABSTRACT FROM AUTHOR]

This work describes the determination of sulfur in some nuts and dried fruits using a high-resolution continuum source electrothermal atomic absorption spectrometer (HR-CS ET AAS) and evaluating the two rotational molecular of carbon monosulfide (CS) at 257.959 nm and 258.056 nm simultaneously. Sulfur was determined in a tungsten coated graphite tube/platform at 257.959 nm and 258.056 nm simultaneously, using thiourea as a calibrant, Pd/citric acid as a modifier and applying a pyrolysis temperature of 800 °C and a vaporization temperature of 2200 °C. The calibration curve prepared from thiourea was linear up to 2500 ng of S. The limit of detection and characteristic mass of the method were 21.6 ng and 7.4 ng of S, respectively. The accuracy of the method was tested by analyzing certified reference spinach, milk powder, tea samples applying linear calibration technique prepared from thiourea aqueous standard. The results were in good agreement with the certified values. [ABSTRACT FROM AUTHOR]

During the enzymatic reaction of the heme-protein Horseradish peroxidase (HRP) with hydrogen peroxide there are changes in the molecular absorption spectra of HRP and its different oxidation states which can be used for quantitative determination of the substrate. One of these intermediate oxidation states is the HRPII, with iron as an oxyferryl. This compound is assumed to be responsible for the organophosphate pesticide degradation in the Fenton reaction. In this work, the enzymatic HRP–H2O2 reaction has been studied, based on the effect of different pesticides on the mechanism reaction; these modifications have been used for the quantitative determination of pesticides. A mathematical model has been developed relating to the analytical signal with the pesticide concentration. Three organophosphate pesticides (diazinon, trichlorfon and tetrachlorvinphos) and one sulfamide (dichlofluanid) have been used to demonstrate the viability of the methodology and the accomplishment fulfillment of the model. Tetrachlorvinphos was chosen as the pesticide model to develop the optical sensor film for continuous pesticide determination, consisting of HRP immobilized in a polyacrylamide gel. The sensor can be used for at least 15 days and responds linearly to tetrachlorvinphos concentrations in the range from 4.0Ã?10−7 to 4.0Ã?10−6 molL−1. The main advantage of the methodology is its reversibility in contrast to the irreversible Fenton reaction. The HRP–H2O2 methodology has been used to measure the pesticides in a waste water sample spiked with tetrachlorvinphos. [ABSTRACT FROM AUTHOR]

Abstract: A suite of programs for high resolution infrared-microwave atmospheric radiative transfer modeling has been developed with emphasis on efficient and reliable numerical algorithms and a modular approach appropriate for simulation and/or retrieval in a variety of applications. The Generic Atmospheric Radiation Line-by-line Infrared Code — GARLIC — is suitable for arbitrary observation geometry, instrumental field-of-view, and line shape. The core of GARLIC's subroutines constitutes the basis of forward models used to implement inversion codes to retrieve atmospheric state parameters from limb and nadir sounding instruments. This paper briefly introduces the physical and mathematical basics of GARLIC and its descendants and continues with an in-depth presentation of various implementation aspects: An optimized Voigt function algorithm combined with a two-grid approach is used to accelerate the line-by-line modeling of molecular cross sections; various quadrature methods are implemented to evaluate the Schwarzschild and Beer integrals; and Jacobians, i.e. derivatives with respect to the unknowns of the atmospheric inverse problem, are implemented by means of automatic differentiation. For an assessment of GARLIC's performance, a comparison of the quadrature methods for solution of the path integral is provided. Verification and validation are demonstrated using intercomparisons with other line-by-line codes and comparisons of synthetic spectra with spectra observed on Earth and from Venus. [Copyright &y& Elsevier]

The metal-insulator transition (MIT) is normally assisted by certain external power input, such as temperature, pressure, strain, or doping. However, these may increase the disorder of the crystal or cause other effects, which makes device fabrication complicated and/or hinders large-scale application. Here, we adopt a new approach to obtain robust modulation of physical properties in magnetic semiconductor (Ga,Mn)As by surface molecular modification. We have probed both sides of the MIT with n- and p-type molecular doping. Density functional theory calculations are carried out to determine the stable absorption configuration and charge transfer mechanism of electron acceptor and donor molecules on the semiconductor surface. Both experimental and theoretical results confirm a remarkable modulation in carrier concentrations without introducing impurities or defects. This work points out the possibility of effectively tuning physical properties of solid-state materials by functional molecules, which is clean, flexible, nondestructive, and easily achieved.