IR Instruments Research Articles

The experiment on the ISS with low-temperature fixed points – a stage in developing high-stable on-board fixed-point blackbodies for in-flight calibrating the Earth observation IR instruments

The experiment on the ISS with low-temperature fixed points – a stage in developing high-stable on-board fixed-point blackbodies for in-flight calibrating the Earth observation IR instruments

Unraveling the birthplaces of NGC 2070’s massive stars, tracked with MUSE and revealed with JWST

The formation of massive O-type stars cannot be simply explained as a scaled-up version of the accretion mechanisms observed in lower-mass stars. Understanding these processes necessitates systematic studies of their early stages, which are challenging to identify. Forming massive stars remain embedded in their dense nursery clouds, and IR instruments with high spatial resolution capabilities are needed to better observe them. Despite these challenges, MUSE optical observations of the massive cluster NGC 2070 successfully detected potential star-forming regions through spatially resolved electron density maps. To further explore these regions, the James Webb Space Telescope (JWST) utilized its NIRCam and MIRI instruments to penetrate optically obscured areas. This study examines two specific regions in the southeast part of the NGC 2070 MUSE density map, where tracks of highly dense point sources were identified. NIRCam, partially overlapped with MIRI, resolved these MUSE findings, revealing a procession of stellar point sources in the projected images. The detections are associated with elongated clouds, suggesting greater proper motions compared to the surrounding interstellar medium. These findings may indicate the presence of runaway candidates in the early stages of their evolution that are following common escape routes. This would support the notion that dynamical ejection is an efficient mechanism for the formation of massive runaway stars during early stages and likely plays a significant role in the origin of O-type field stars. However, additional data are required to confirm this scenario and rule out other ionizing feedback mechanisms, such as those observed in the formation of pillar-like structures around HII regions in the Milky Way. MUSE electron density mapping effectively captures the complexity of NGC 2070’s interstellar medium and highlights targets for subsequent spectroscopic follow-ups, as demonstrated by the JWST data in the two fields studied.

Multi-instrument spectroscopic study for authentication of curcumin content in commercial turmeric powders using machine learning algorithms

Adulteration during processing of turmeric powder not only causes health risks for the consumers but also affects its quality. There is a need for rapid and non-invasive analysis of its active ingredient, curcumin, during the supply-chain. In the present study a total six IR instruments ranging from hand-held (NIR), portable (NIR) and standalone (FTNIR and FTIR) were used to obtain spectral data of 160 different turmeric samples. The curcumin content quantified using HPLC procedure was used as the response variable for analytical model using machine learning tools. Real coded genetic algorithm (RCGA) as the variable selection procedure provided most critical variables in the sets of 10, 20, 30 and 40 variables. Sensitivity analysis has revealed the most critical fingerprint(s) in authenticating curcumin across all the instruments. The hand-held (NIR) device with only 20 spectral variables resulted in 93 % accuracy using SVM classifier, and RP (regression co-efficient of prediction) values of 0.970 and 0.997 using RF and XGBoost, respectively. In case of FTNIR and FTIR instruments 100 % classification accuracy was achieved using SVM, whereas RF and XGBoost resulted in RP values greater than 0.93. This study enables classification and quantification of curcumin content in commercial turmeric powders using non-destructive methodology.

Transformational Leadership and Industrial Relation Instruments as a Determinant of Firm’s Performance Mediated by Industrial Relation Climate

Globally companies have faced conflict in the workplace which led to unfavorable impacts on organizational performance. The dispute would cause an unfavorable workplace climate which leads to a reduction in the level of the firm’s productivity and negatively impact the chance of the organization's survival. The objective of the study is to confirm the relationship between Transformational Leadership and IR instruments to IR Climate. And how IR climate relates to firm performance. A Descriptive quantitative study of 406 respondents from various industries in Indonesia was conducted. Participants of this study were from various stakeholders in organizations such as Directors, Managers, Employees, Heads of Unions, and members of unions from various types of organizations. The result shows that Transformational Leadership and Industrial Relations Instruments positively influence Industrial Relation Climate. And Industrial Climate has a positive relation to the Firm’s Performance.

Pengaruh Penambahan Variasi KJ-CTAB Terhadap Karakteristik ZnO/KJ-CTAB yang Disintesis Menggunakan Metode Impregnasi Basah

Semiconductor photocatalysts have great potential in solving environmental problems. The photocatalyst process using a semiconductor is one of the technology to oxidize organic compounds such as dyes. Orange peel (KJ) is one of the adsorbents that have the potential for purification of dyes that increase the photocatalytic activity of ZnO material. This study aims to determine the optimum variation of KJ-CTAB to be added to ZnO material. The results of the synthesis of ZnO/KJ-CTAB varasis 1:25, 2:25, and 3:25 (w/v) using the wet impregnation method were characterized on IR, XRD, SEM, DR-UV, and BET instruments. The results showed that FTIR also showed the presence of ZnO bonds in all samples, C-H in samples varied from 1:25, 2:25, and 3:25 (w/v). The XRD results showed that the percentage of crystallinity decreased and the SEM results showed that ZnO/KJ-CTAB 1:25 had a more homogeneous morphology. Based on the results of DR-UV ZnO/KJ-CTAB 1: 25 (w/v) has a band gap energy value of 3.20 eV which is good for use in photocatalyst processes. BET results show that all samples belong to the mesoporous size.

Identification of Smectites by IR and LIBS Instruments of Supercam Suite Onboard Mars 2020 Perseverance Rover: Comments on the Non-retrieval of First Drill Core

Identification of Smectites by IR and LIBS Instruments of Supercam Suite Onboard Mars 2020 Perseverance Rover: Comments on the Non-retrieval of First Drill Core

Martian atmospheric water vapor abundances in MY26-30 from Mars Express PFS/LW observations

I report on retrievals of water vapor abundances in the Martian atmosphere using observations by Planetary Fourier Spectrometer Long Wavelength channel (PFS/LW) aboard the Mars Express (MEx) spacecraft. PFS/LW observations used in this work cover almost 4 Martian Years from Ls ~ 331° in MY26 (January 2004) to Ls ~ 209° in MY30 (December 2010). Vapor abundances were retrieved from nadir spectra collected over a range of latitudes, seasons and local hours. Most of the retrieved abundances correspond to daytime observations at local hours from 8 to 17 h. The spatial and temporal coverage of retrieved abundances varies significantly between years of observations, with the best coverage in MY27 and MY29. The average annual water vapor cycle observed by PFS/LW is qualitatively similar to the cycle observed by the Thermal Emission Spectrometer (TES) onboard Mars Global Surveyor (MGS), however the PFS/LW abundances are systematically lower. The likely reason for this difference is the difference in the respective water vapor absorption models. Comparison between PFS/LW abundances for time periods with low atmospheric dust opacity between different years of observations does not show significant interannual variability. PFS/LW abundances are significantly lower than the abundances retrieved from observations by Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on Mars Reconnaissance Orbiter (MRO) in MY29. The difference is likely due to the differences in retrieval models for different spectral regions used by CRISM and PFS/LW to retrieve water vapor abundances and due to different environmental parameters used in the retrievals. PFS/LW abundances are generally similar to abundances retrieved by the SPICAM IR instrument, except in the polar regions during summer. The difference likely arises because of non-uniform vertical distribution of water vapor in the summer polar atmospheres and different sensitivities of the two instruments to vertical distribution of vapor. The PFS/LW observed systematic longitudinal dependence of scaled vapor abundances in the northern tropics with two maxima at longitudes ~30–60°E and ~ 240–270°E. This longitudinal dependence resembles a standing wave forced in the local atmospheric flow by topography and surface thermo-physical properties. The longitudinal non-uniformity of water vapor possibly shows a seasonal dependence increasing around solstices and decreasing around equinoxes. During northern spring in the Northern Polar Region (NPR) PFS/LW observed an increase of vapor near the edge of the seasonal cap interpreted as a buildup of vapor by repeated cycles of water ice freezing and sublimation at the cap edge. Similar, but weaker and longitudinally non-uniform increase in vapor near the edge of the seasonal cap is observed in the Southern Polar Region (SPR) during spring. Tentative signs of water vapor diurnal variability were observed in the PFS/LW data over northern mid-latitudes during late spring and early summer, potentially reflecting vapor exchange between the regolith and the atmosphere.

Novel, Environment-Friendly Cellulose-Based Derivatives for Tetraconazole Removal from Aqueous Solution.

In this study, cellulose-based derivatives with heterocyclic moieties were synthesized by reacting cellulose with furan-2-carbonyl chloride (Cell-F) and pyridine-2,6-dicarbonyl dichloride (Cell-P). The derivatives were evaluated as adsorbents for the pesticide tetraconazole from aqueous solution. The prepared adsorbents were characterized by SEM, TGA, IR, and H1 NMR instruments. To maximize the adsorption efficiency of tetraconazole, the optimum conditions of contact time, pH, temperature, adsorbent dose, and initial concentration of adsorbate were determined. The highest removal percentage of tetraconazole from water was 98.51% and 95% using Cell-F and Cell-P, respectively. Underivatized nanocellulose was also evaluated as an adsorbent for tetraconazole for comparison purpose, and it showed a removal efficiency of about 91.73%. The best equilibrium adsorption isotherm model of each process was investigated based on the experimental and calculated R2 values of Freundlich and Langmuir models. The adsorption kinetics were also investigated using pseudo-first-order, pseudo-second-order, and intra-particle-diffusion adsorption kinetic models. The Van’t Hoff plot was also studied for each adsorption to determine the changes in adsorption enthalpy (∆H), Gibbs free energy (∆G), and entropy (∆S). The obtained results showed that adsorption by Cell-F and Cell-P follow the Langmuir adsorption isotherm and the mechanism follows the pseudo-second-order kinetic adsorption model. The obtained negative values of the thermodynamic parameter ∆G (−4.693, −4.792, −5.549 kJ) for nanocellulose, Cell-F, and Cell-P, respectively, indicate a spontaneous adsorption process. Cell-F and Cell-P could be promising absorbents on a commercial scale for tetraconazole and other pesticides.

New fixed point of on-orbit calibration scale based on the In-Bi eutectic alloy for application in novel high-stable space-borne standard sources

The problem of ensuring stability of Earth observation space-borne instruments undertaking long-term temperature measurements within thermal IR spectral range is described. For in-flight reliable control of the space-borne IR instruments characteristics the stability of onboard reference sources should be improved. The function of these high-stable sources will be executed by novel onboard blackbodies, incorporating the melt↔freeze phase transition phenomenon, currently being developed. As a part of these works the task of realizing an on-orbit calibration scale within the dynamic temperature range of Earth observation systems 210−350 K based on fixed-point phase transition temperatures of a number of potentially suitable substances is advanced. The corresponding series of the onboard reference blackbodies will be set up on the basis of the on-orbit calibration scale fixed points. It is shown that the achievement of the target lies in carrying out a number of in-flight experiments with the selected fixed points and the prospective onboard fixed-point blackbodies prototypes. The new In-Bi eutectic alloy melt temperature fixed point (~345 K) is proposed as the significant fixed points of the future on-orbit calibration scale. The results of the new fixed point preliminary laboratory studies have been analyzed. The results allowed to start preparation of the in-flight experiments investigating the In-Bi alloy for the purpose of its application in the novel onboard reference sources.

An Efficient Method for The Synthesis of Dihydropyridine by Hantzsch Reaction with Fe/SiO2 Nano Heterogeneous Catalysts

An efficient method for the synthesis of dihydropyridines (DHPs) by Hantzsch reaction with Fe/SiO2 heterogeneous catalysts was developed. The Fe/SiO2 catalysts was prepared by impregnation method. The catalysts were characterized by IR and SEM instruments. The SEM results indicated that Fe/SiO2 nano spheres were formed. The reaction procedure involved reaction of aldehyde, ethyl acetoacetate (EAA), ammonium acetate (NH4OAc) and ethanol under reflux. The study was focused on optimizing reactions conditions: Standardization of catalyst, substrate of study and solvent study. In order to identify the best active catalysts, five different ratios of catalyst were synthesized and evaluated for the title reaction under similar conditions. To standardize the active catalysts, different temperature conditions (i.e. room temperature, 60 ºC and 80 ºC) as well as catalysts amounts were evaluated. Under these established conditions, 2.5% Fe/SiO2 was the best active catalysts that resulted. Benzaldehyde and p-anisaldehyde were used to study the effect of having various substrates on the conversion and reaction time, especially the substituted aldehydes. The best results were obtained by reacting p-anisaldehyde with EAA, NH4OAc and ethanol at 60 ºC with 0.3 grams of 2.5% Fe/SiO2 heterogeneous catalysts. Thin Layer Chromatography (TLC) monitoring of the reaction mixture showed no selectivity at high temperatures (80 ºC) with 15% Fe/SiO2. Standardization of solvent study was executed with two solvents, ethanol and acetonitrile. The product dihydropyridines were analyzed using gas chromatography-mass spectrometry (GC-MS). The melting points of the products were compared with authentic samples reported in the literature. Hence, the Fe/SiO2 catalysts is eco-friendly and economically developed for the title reaction. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

IR SPECTRUMS AND CHARACTERISTICS OF Na-CMC FOUND IN SEVERAL TYPES OF PLANTS: A REVIEW

Natrium carboxymethyl cellulose (Na-CMC) is a cellulose derivative that is produced commercially in greater amounts than other cellulose derivatives. Natrium carboxymethyl cellulose (Na-CMC) is a linear cellulose polymer and is an anion compound that is biodegradable, odourless, colourless, non-toxic, tasteless, flexible and transparent. Natrium carboxymethyl cellulose (Na-CMC) is usually found in the form of granules or powders which are soluble in water but cannot dissolve in organic solutions. Natrium carboxymethyl cellulose (Na-CMC) has a pH range of 6.5-8 and is stable in a pH range of 2-10. Na-CMC is found in several types of plants, such as water hyacinth, durian, elephant grass, rice, peanuts, pineapple, corn, oranges, baobab and sugar cane. Na-CMC is obtained from these plants. Na-CMC is widely used in the pharmaceutical, cosmetic, food, paper, textile, lithography and tobacco industries. Na-CMC sourced from natural materials is characterized by Fourier Transform Infrared Spectroscopy (FTIR). The functional groups of cellulose and carboxymethyl cellulose were investigated using infrared spectroscopy spectra. The pellets were made with CMC with potassium bromide (KBr). The absorbance level was measured for the wave number 3800-400 cm-1. The results of the extraction of cellulose and carboxymethyl cellulose were characterized using the Fourier Transform IR (FTIR) instrument. To obtain the spectrum, the pellets made from the sample were grounded with KBr. Transmission was measured in the wave number range 4000-4400cm-1. Infrared spectroscopy is one of the most versatile techniques used in chemistry and certainly one of the most important analytical methods available. It is a versatile experimental technique and it is relatively easy to obtain a reliable spectrum from a sample in almost any situation. In general, the infrared spectrum is used to determine the functional group of an organic compound and to find out the structural information of an organic compound.

The need for rethinking the model of assessing value in the digital economy context

Abstract In recent years, companies have begun to promote an economy based on knowledge and information, characterized by rapid economic changes, so the production of tangible goods has no longer been the main source of value, this being replaced by the creation and management of intangible assets, which are often not reflected in the accounting documents at the real market value because of the restrictive criteria for accounting valuation and recognition. Nowadays, the economy is based mainly on intangible assets and therefore they must be recognized in the financial statements of the companies, so that the shareholders and the investors have a clearer picture of company value. This paper aims to propose a model that can analyze the effects of intellectual capital and subcomponents of intangible assets on company value and the sustainable growth of firms listed on the Bucharest Stock Exchange. Until now, it is unknown which kind of sub-components of intangible assets make firms listed at Bucharest Stock Exchange to have sustainable growth or are more useful to enhance firm value. The proposed model includes data referring to intellectual capital, computerized information, innovative property, economic competences and VEKTOR index, which was developed by the Romanian Investor Relations Association so that the shareholders and the investors have a clearer picture of company when it comes to Relationship with Investors, Corporate Governance, Proactive Approach in IR, Interactive IR Instruments, Coverage by Financial Analysts and Sustainability.

Electrochemical polymerization of para-chloroaniline as highly redox-active poly(para-chloroaniline) on graphitized mesoporous carbon surface

Owing to the high demand of conducting molecular systems for various electronics and technological applications, development of new polyaniline (PANI)/carbon nanomaterial is a continued research interest in cross-disciplinary area of material chemistry. In the literature, for the preparation of PANI/carbon nanomaterial composite electrode systems ex-situ preparation method, in which, chemical oxidation of aniline in presence of carbon nanomaterial, followed by modification on solid substrate has been widely adopted. In this work, a systematic study has been carried out for in-situ electrochemical polymerization of 4-chloroaniline and other substituted aniline monomers to respective PANI on graphitized mesoporous carbon (GMC), that show porous structure and enormous sp2 sites to aniline and PANI for π-π interaction, unusually in neutral pH condition. The new GMC@PANI modified electrode showed a highly redox active peak at Eo’ = 0.12 V vs Ag/AgCl in pH 7 phosphate buffer solution. No such behaviour was noticed when an unmodified glassy carbon was used as working electrode for the polymerization in the above mentioned condition. The redox peak is found to be stable, surface-confined and Nernstian type of proton-coupled electron-transfer in nature. Based on the physicochemical characterization techniques using Raman, IR, X-Ray photoelectron-spectroscopy, scanning electron-microscope and scanning electrochemical microscope (SECM) instruments and electrochemical studies with several ortho, para and meta substituted aniline monomers, mechanism for the in-situ polymerization has been revealed that 4-chloroaniline monomer has undergone a surface-confined electrochemical oxidation reaction with involvement of aniline(4-Cl)-cation radical species, anti-orientation of the monomer (that exist in solution phase), head-to-tail collision (C-N bonding), ejection of the para-substituents as Cl- and Cl•, partial chlorination and PANI(4-Cl) formation mechanism. Such a PANI(4-Cl) film showed a wave-like 2D molecular film structure with enhanced redox and electrical property over the conventional PANI system.

Silver nanoparticles on copper foam as substrate for full range mid-infrared surface enhanced infrared absorption spectroscopy in transmission configuration

The availability of sensitive, reproducible, and broad spectral window range surface enhanced infrared absorption spectroscopy (SEIRAS) substrate is essential to the wide application of SEIRAS technique. Here, a facile method was proposed for the preparation of full mid-infrared range transmission surface-enhanced infrared absorption spectroscopy (T-SEIRAS) substrate, where silver nanoparticles (Ag NPs) was synthesized in situ by immersing copper foam into the silver nitrate solution with the help of hydroxylamine hydrochloride. The T-SEIRAS substrate was characterized with Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscope (SEM) and X-ray Photoelectron Spectroscopy (XPS). It was found that the spectral window of the substrate was from 600 to 4000 cm−1. The apparent signal enhancement factor of the T-SEIRAS substrate was found to be about 35 times with the utilization of 11-mercaptoundecanoic acid (MUA) as probe molecule. Finally, the T-SEIRAS spectrum of E. coli was successfully obtained. It is expected that this type of T-SEIRAS substrate could be used in inexpensive IR instruments for field sensing applications.

Large-Scale and Well-Ordered Assembly of Microspheres in a Small Container.

Colloidal self-assembly monolayers (SAMs) formed by the Langmuir?Blodgett (LB) process have been widely applied in modern research. The quality of the closely packed 2D or 3D arrays would determine their performance and applications. Herein, we study the influence of the surface wettability of containers on the self-assembly process of polystyrene microspheres using LB technology. It is found that the variation of surface tension at the gas/liquid/solid phase determines the quality of the PS colloidal SAMs. By carefully controlling the surface wettability of the containers, a square centimeter level of well-ordered polystyrene (PS) microsphere SAMs in a small polyethylene (PE) container can be achieved. This method can be used to fabricate PS SAMs with different sphere sizes. In addition, the PS SAMs can be easily transferred onto silica-coated silicon and silicon wafers for further fabricating triangle antenna arrays at a square centimeter level that allows for the study the IR resonances of antennas with conventional IR instrument. The present study provides a simple approach to the fabrication of large-scale and well-ordered colloidal SAMs for further applications.

Background-limited Imaging in the Near Infrared with Warm InGaAs Sensors: Applications for Time-domain Astronomy

Abstract We describe test observations made with a customized 640 × 512 pixel indium gallium arsenide (InGaAs) prototype astronomical camera on the 2.5 m DuPont telescope. This is the first test of InGaAs as a cost-effective alternative to HgCdTe for research-grade astronomical observations. The camera exhibits a background of 113 e– s–1/pixel (dark + thermal) at operating sensor temperature T = −40°C, maintained by a simple thermoelectric cooler. The optomechanical structure floats at ambient temperature with no cold stop, unlike most IR instruments which must be cooled to mitigate thermal backgrounds. Measurements of the night sky using a reimager scaled at 0.″4/pixel show that the sky flux in Y is comparable to the dark current. At J the sky exceeds dark current by a factor of four, dominating the noise budget. The read noise (∼43 e−) falls below sky + dark noise for exposures of t > 7 s in Y and 3.5 s in J. We observed several representative science targets, including two supernovae, a z = 6.3 quasar, two local galaxies monitored for IR transients, and a galaxy cluster at z = 0.87. We observe a partial transit of the hot Jupiter HATS-34b, demonstrating the photometric stability to detect a 1.2% transit. A tiling of larger-format sensors would produce an IR survey instrument with significant cost savings relative to HgCdTe-based cameras, if one is willing to forego the K band. Such a camera would be sensitive for a week or more to isotropic emission from r-process kilonova ejecta similar to that observed in GW170817, over the full 190 Mpc horizon of Advanced LIGO.

Antenna array-enhanced attenuated total reflection IR analysis in an aqueous solution.

Attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) is a powerful technique that provides structural and functional information during dynamic reactions in aqueous solutions. One existing limitation is the sensitivity to extract the signals of trace-level analytes from the background water in situ and in real time. Here, we proposed a novel ATR-SEIRAS platform that integrated a large-scale triangle gold antenna array onto a conventional ATR-IR platform to increase the sensitivity of this analytical technique. A square centimeter level well-ordered gold antenna array was fabricated onto an Si prism via nanosphere lithography. The size-dependent antenna array resonance had weak correlation with the incident polarization and antenna orientation, allowing antenna array-enhanced IR detection without the requirement of a microscope. In addition, the antenna resonance shift that occurred due to analyte adsorption-induced refractive index variation could be minimized benefiting from the high refractive index of Si (3.4). As a demonstration, we dynamically monitored the adsorption of the trace levels of proteins on top of the antenna array with a real signal enhancement factor larger than 300. Our platform opens an avenue to apply antenna array-enhanced IR spectroscopy in an aqueous environment measured via commercial IR instruments, which is extremely promising for the interfacial applications that require signal enhancement.

Mineralogy and geochemistry of the Lokoundje alluvial clays from the Kribi deposits, Cameroonian Atlantic coast: Implications for their origin and depositional environment

The Lokoundje alluvial clay deposits are located at the left floodplain of the Lokoundje River, towards the estuary in the Kribi region. The mineralogical and geochemical features of the Lokoundje River fine-grained sediments have been reported using XRD, XRF, ICP-MS, and IR instruments in order to understand their provenance and depositional history. The Lokoundje watershed covers a surface area of about 5381 km2. The basement of this watershed is made up of gneisses, amphibolites, migmatites, charnockites, and pyroxenites from the Nyong and Ntem units, in the NW border of the Congo craton. The alluvial materials are about 100 cm thick and cover a total area of 1.4 km2. They are mainly plastic clays with silty-clayey texture and four colors (yellow, red yellow, white, and light grey). The mineral assemblage is composed of kaolinite, quartz, illite, gibbsite, goethite, rutile, and interstratified illite-vermiculite. The infra-red data associated with those of XRD portray the disordering of kaolinite. These materials are mostly constituted by SiO2 (44.33–69.19 wt%, av. = 51.17 wt% with n = 18) and Al2O3 (20.69–30.26 wt%, av. = 26.07 wt%) with very low Fe2O3 contents (1–7.71 wt%, av. = 3.35 wt%). The SiO2/Al2O3 ratio range between 1.46 and 4.1 (av. = 2.06). The alkali contents (Na2O + K2O) are below 5 wt%. ICV, CIA, PIA, and SiO2/Al2O3 portray high degree of chemical weathering in the source area as well as the maturity of sediments. The trace element behavior is quite different probably due to the mixed source rocks; Ba, Sr, Zn have high contents while several elements such as Th and U show low contents. The REE contents are also variable; their concentrations vary between 92 and 1065 ppm (av. = 307 ppm). The mineral assemblage associated with the geochemical data reveal that REE are mainly housed in clay minerals. The behavior of REE is also marked by the abundance of LREE (LREE/HREE = 19.69–34.62). The REE chondrite-normalized spectra confirm the LREE-abundance and exhibit negative Eu anomalies. The PAAS-normalized patterns reveal slight positive Eu anomalies and negative Ce anomalies. The (La/Yb)N values (3.30–8.43, av. = 5.71) display low degree of REE-fractionation in the Lokoundje watershed. The morphological, mineralogical, and geochemical features reveal that the fine-grained sediments derive from the intense weathering of mixed source. The disordering of kaolinite confirms that sediments were sorted during a long transportation before their deposition under oxic conditions (U/Th < 1.25; V/Cr < 2) in the floodplains near the Atlantic coast.

On the use of spectra from portable Raman and ATR-IR instruments in synthesis route attribution of a chemical warfare agent by multivariate modeling

Collecting data under field conditions for forensic investigations of chemical warfare agents calls for the use of portable instruments. In this study, a set of aged, crude preparations of sulfur mustard were characterized spectroscopically without any sample preparation using handheld Raman and portable IR instruments. The spectral data was used to construct Random Forest multivariate models for the attribution of test set samples to the synthetic method used for their production. Colored and fluorescent samples were included in the study, which made Raman spectroscopy challenging although fluorescence was diminished by using an excitation wavelength of 1064 nm. The predictive power of models constructed with IR or Raman data alone, as well as with combined data was investigated. Both techniques gave useful data for attribution. Model performance was enhanced when Raman and IR spectra were combined, allowing correct classification of 19/23 (83%) of test set spectra. The results demonstrate that data obtained with spectroscopy instruments amenable for field deployment can be useful in forensic studies of chemical warfare agents.

The Application of Lab Environment as the External Disturbance in the 3-Stage IR Method for the Facile Discrimination of Danggui Formula Granules

Formula granule (FG), as an improved preparation form of traditional liquid dedoction, is of increasing interest and hence it is necessary to develop facile analytical or discrimination methods. Based on the established 3-Stage IR method, a new external disturbance of lab environment (LE) in which room temperature (RT) is 25-30°C and humidity is 25-30%, is introduced to test its applicability in discrimination of Danggui formula granules from different companies in which the LE is used to affect the prepared KBr pellet to produce enough variations for the 3S-IR method. Firstly, the 2D-spectra and pattern recognition algorithm of principal component analysis (PCA) and hierarchical cluster analysis (HCA) are used to select the analytical basis for 2D-COS IR. Secondly, LE-based 2D-COS IR is used for the discrimination. The newly-established LE-based IR can avoid the complex parts of programmed temperature and sampling in IR instrument, and achieve the discrimination of different Danggui Formula Granules.