Effects of Particle Size on the Attenuated Total Reflection Spectrum of Minerals

Starch mediates and cements densely magnetite-coating of talc, giving an efficient nano-catalyst for three-component synthesis of imidazo[1,2-c]quinazolines

Hot-water-soluble starch (HWSS) was used as a powerful cementing material to produce nano-size conglomerates of talc and magnetite nanoparticles. Coordination of HWSS hydroxyl groups to iron atoms at surface of magnetite leads to grafting and encapsulation of its nanoparticles. The resulting nano-complex showed a higher loading capacity on talc than pristine magnetite nanoparticles. Only a minute amount of HWSS was detected in the fabricated nano-composite Talc\HWSS@Fe3O4. XPS study suggests a considerable interaction between HWSS and Fe3O4 nanoparticles, upon which some of the Fe+3 atoms on surface of Fe3O4 are reduced into Fe+2 atoms. ATR FT-IR spectra of the nano-composite revealed significant delamination of talc sheets on interaction with HWSS-coated Fe3O4 nanoparticles. The nano-composite displayed an efficient catalytic activity in the synthesis of new imidazo[1,2-c]quinazoline derivatives via Grobke-Blackburn-Bienaymé three-component reaction of 4-aminoquinazoline, arylaldehydes and isocyanide. The efficiency of the method was exemplified by synthesizing 7 new products in fairly high yields (68-83%) within short reaction times (24-30 min) using a catalytic amount of the catalyst under solvent-free condition at 120 °C. Clean and fast synthesis of the products and convenient separation of the robust nano-catalyst are the prominent advantages of the present method. The nano-catalyst was properly characterized.

Blood molecular profile to predict genotoxicity from exposure to antineoplastic drugs

Genotoxicity is an important information that should be included in human biomonitoring programmes. However, the usually applied cytogenetic assays are laborious and time-consuming, reason why it is critical to develop rapid and economic new methods. The aim of this study was to evaluate if the molecular profile of frozen whole blood, acquired by Fourier Transform Infrared (FTIR) spectroscopy, allows to assess genotoxicity in occupational exposure to antineoplastic drugs, as obtained by the cytokinesis-block micronucleus assay. For that purpose, 92 samples of peripheral blood were studied: 46 samples from hospital professionals occupationally exposed to antineoplastic drugs and 46 samples from workers in academia without exposure (controls). It was first evaluated the metabolome from frozen whole blood by methanol precipitation of macromolecules as haemoglobin, followed by centrifugation. The metabolome molecular profile resulted in 3 ratios of spectral bands, significantly different between the exposed and non-exposed group (p < 0.01) and a spectral principal component-linear discriminant analysis (PCA-LDA) model enabling to predict genotoxicity from exposure with 73 % accuracy. After optimization of the dilution degree and solution used, it was possible to obtain a higher number of significant ratios of spectral bands, i.e., 10 ratios significantly different (p < 0.001), highlighting the high sensitivity and specificity of the method. Indeed, the PCA-LDA model, based on the molecular profile of whole blood, enabled to predict genotoxicity from the exposure with an accuracy, sensitivity, and specificity of 92 %, 93 % and 91 %, respectively. All these parameters were achieved based on 1 μL of frozen whole blood, in a high-throughput mode, i.e., based on the simultaneous analysis of 92 samples, in a simple and economic mode. In summary, it can be conclude that this method presents a very promising potential for high-dimension screening of exposure to genotoxic substances.

Nickel Slag/Laterite Soil and Nickel Slag/Iron Sand Nanocomposites: Structural, Optical, and Electromagnetic Absorption Properties

Efforts to produce microwave absorber materials that are inexpensive and environmentally friendly have become a means of greening the environment. The breakthrough can be focused on industrial waste and natural materials for functional purposes and how to enhance their performance. We successfully synthesized nickel slag/laterite soil (NS/LS) and nickel slag/iron sand (NS/IS) nanocomposites using a simple mechanical alloying technique, and the electromagnetic (EM) wave absorption capacities of the nanocomposites were measured using a vector network analyzer. The structural properties of the nanocomposites were analyzed by X-ray diffraction spectroscopy, where the results of the analysis showed that NS/IS has the largest crystallite size (15.69 nm) and the highest EM wave absorption performance. The optical properties of the nanocomposites were determined from their Fourier transform infrared spectra using the Kramers-Kronig relation. As determined through a quantitative analysis of the optical properties, the distance between the longitudinal and transversal optical phonon wavenumber positions (Δ(LO - TO) = 65 cm^-1) is inversely proportional to the reflection loss. The surface morphologies of the nanocomposites were analyzed by scanning electron microscopy, and the particle diameters were observed by binary image and Gaussian distribution analyses. The nanocomposite surface exhibits a graded-like morphology, which indicates multiple reflections of the EM radiation, consequently reducing the EM interference. The best nanocomposite for an attenuated EM wave achieved a reflection loss of -39.14 dB at 5-8 GHz. A low penetration depth has implications for the electrical charge tuning of the storage and composite magnets. Finally, the EM absorption properties of NS/IS and NS/LS indicate a 2-mm-thick environmentally friendly nanocomposite for EM absorption.

Point-of-care community drug checking technologies: an insider look at the scientific principles and practical considerations

Drug checking is increasingly being explored outside of festivals and events to be an ongoing service within communities, frequently integrated within responses to illicit drug overdose. The choice of instrumentation is a common question, and the demands on these chemical analytical instruments can be challenging as illicit substances may be more complex and include highly potent ingredients at trace levels. The answer remains nuanced as the instruments themselves are not directly comparable nor are the local demands on the service, meaning implementation factors heavily influence the assessment and effectiveness of instruments. In this perspective, we provide a technical but accessible introduction to the background of a few common drug checking methods aimed at current and potential drug checking service providers. We discuss the following tools that have been used as part of the Vancouver Island Drug Checking Project in Victoria, Canada: immunoassay test strips, attenuated total reflection IR-absorption spectroscopy, Raman spectroscopy from powder samples, surface-enhanced Raman scattering in a solution of colloidal gold nanoparticles, and gas chromatography-mass spectrometry. Using four different drug mixtures received and tested at the service, we illustrate the strengths, limitations, and capabilities of such instruments, and expose the scientific theory to give further insight into their analytical results. Each case study provides a walk-through-style analysis for a practical comparison between data from several different instruments acquired on the same sample. Ideally, a single instrument would be able to achieve all of the objectives of drug checking. However, there is no clear instrument that ticks every box; low cost, portable, rapid, easy-to-use and provides highly sensitive identification and accurate quantification. Multi-instrument approaches to drug checking may be required to effectively respond to increasingly complex and highly potent substances demanding trace level detection and the potential for quantification.

Deciphering strontium sulfate precipitation via Ostwald's rule of stages: From prenucleation clusters to solution-mediated phase tranformation

Multiple-step nucleation pathways have been observed during mineral formation in both inorganic and biomineral systems. These pathways can involve precursor aqueous species, amorphous intermediates, or metastable phases. Despite the widespread occurrence of these processes, elucidating the precise nucleation steps and the transformation mechanisms between each step remains a challenging task. Using a suite of potentiometric, microscopic, and spectroscopic tools, we studied the nucleation pathway of SrSO₄ as a function of the physico-chemical solution parameters. Our observations reveal that below a threshold supersaturation, nucleation is driven by bound species, akin to the prenucleation cluster model, which directly leads to the formation of the stable phase celestine, SrSO₄. At higher supersaturations, this situation is altered, with nucleation dominated by the consumption of free ions. Importantly, this change in nucleation mechanism is coupled to the formation of a hemihydrate metastable phase, SrSO₄ · 1/2H₂O, which eventually transforms into celestine, adhering to Ostwald's rule of stages. This transformation is a solution-mediated process, also occurring in the presence of a fluid film and is controlled by the physico-chemical parameters of the surrounding environment. It proceeds through the dissolution of the metastable phase and the de novo crystallization of the final phase. Overall, our results reveal that ion association taking place during the prenucleation stage dictates whether the nucleation pathway goes through an intermediate phase or not. This also underlines that although Ostwald's rule of stages is a common process, it is not a prerequisite for mineral formation-even in systems where it can occur.

A review of conventional and rapid analytical techniques coupled with multivariate analysis for origin traceability of soybean

Soybean has developed a reputation as a superfood due to its nutrient profile, health benefits, and versatility. Since 1960, its demand has increased dramatically, going from a mere 17 MMT to almost 358 MMT in the production year 2021/22. These extremely high production rates have led to lower-than-expected product quality, adulteration, illegal trade, deforestation, and other concerns. This necessitates the development of an effective technology to confirm soybean's provenance. This is the first review that investigates current analytical techniques coupled with multivariate analysis for origin traceability of soybeans. The fundamentals of several analytical techniques are presented, assessed, compared, and discussed in terms of their operating specifics, advantages, and shortcomings. Additionally, significance of multivariate analysis in analyzing complex data has also been discussed.

A Critical Review for Real-Time Continuous Soil Monitoring: Advantages, Challenges, and Perspectives

Most soil quality measurements have been limited to laboratory-based methods that suffer from time delay, high cost, intensive labor requirement, discrete data collection, and tedious sample pretreatment. Real-time continuous soil monitoring (RTCSM) possesses a great potential to revolutionize field measurements by providing first-hand information for continuously tracking variations of heterogeneous soil parameters and diverse pollutants in a timely manner and thus enable constant updates essential for system control and decision-making. Through a systematic literature search and comprehensive analysis of state-of-the-art RTCSM technologies, extensive discussion of their vital hurdles, and sharing of our future perspectives, this critical review bridges the knowledge gap of spatiotemporal uninterrupted soil monitoring and soil management execution. First, the barriers for reliable RTCSM data acquisition are elucidated by examining typical soil monitoring techniques (e.g., electrochemical and spectroscopic sensors). Next, the prevailing challenges of the RTCSM sensor network, data transmission, data processing, and personalized data management are comprehensively discussed. Furthermore, this review explores RTCSM data application for updating diverse strategies including high-fidelity soil process models, control methodologies, digital soil mapping, soil degradation, food security, and climate change mitigation. Finally, the significance of RTCSM implementation in agricultural and environmental fields is underscored through illuminating future directions and perspectives in this systematic review.

FTIR Photoacoustic and ATR Spectroscopies of Soils with Aggregate Size Fractionation by Dry Sieving

Granulometric fractionation as a source of additional information on organic-matter and inorganic matrix components of soils using FTIR-photoacoustic spectroscopy (FTIR-PAS) supported by attenuated-total reflection FTIR spectroscopy (ATR-FTIR) for a wide range of aggregate fractions (10-5000 μm) was used to compare the sensitivity, reproducibility, information contents, and representativity of fractionated samples. For chernozem and sod-podzolic soils and different agricultural-use chernozem samples, differences in the composition were found, manifested in normalized spectra of microaggregate fractions, with the range of 10-100 μm bearing the complete information. Most changes are observed in the soil organic matter range (1900-1340 cm-1), although these changes are slight, and in the soil-matrix region (550-300 cm-1). The latter region increases the intensity of bands corresponding to amorphous silica and clay minerals in fine fractions, while the intensity of bands attributed to quartz lattice vibrations decreases. FTIR-PAS spectra do not differ considerably at high interferometer modulation frequencies as the signal-penetration depth is comparable with particle sizes. The soil fractions below 20 μm result in the maximum sensitivity, reproducibility, and signal-to-noise ratio, showing no changes from coarser fractions by the information content and, thus, providing representative samples for analysis. The fractionation shows more differences in the sod-podzolic and chernozem soil fractions than the whole soil spectra. FTIR-PAS provides better sensitivity and reproducibility in the 4000-2000 cm-1 region and ATR-FTIR in the 2000-100 cm-1 region.

Solid acid catalysts produced by sulfonation of petroleum coke: Dominant role of aromatic hydrogen

Carbon based solid waste materials have been intensively investigated for the preparation of solid acid catalysts through sulfonation, but the acidity varies significantly depending on the material. In this study, the role of aromatic hydrogen in sulfonation with concentrated H₂SO₄ was investigated using petroleum coke (petcoke), graphite, and biochar as the carbon materials. Through ball milling and calcination, the amount of aromatic hydrogen on the petcoke could be increased or decreased, respectively. After sulfonation at 80 °C with concentrated H₂SO₄, the produced acidity (i.e., -SO₃H groups) increased as the amount of aromatic hydrogen increased from essentially no acidity on graphite to 0.55 mmol/g on biochar and 1.25 mmol/g on petcoke (particle sizes of 45-90 μm) indicating the importance of aromatic hydrogen during sulfonation. Calcination (350 °C for 1 h) of the petcoke before sulfonation decreased the acidity to 0.59 mmol/g, while ball milling (with isopropanol and silica for 24 h) increased the acidity to 3.73 mmol/g. The sulfonated petcoke samples were used as catalysts for the esterification reaction between octanoic acid and methanol at 60 °C and the turnover frequencies were 48-85 h^-1. The results give insights on the preparation of solid acid catalysts from carbon materials and highlight the application of petcoke without activation as a feedstock for esterification catalysts.

The Influence of the Size and Oxidation Degree of Graphene Flakes on the Process of Creating 3D Structures during its Cross-Linking

This article presents the results of the cross-linking of oxidized flake graphene (GO) using hydrazine at room temperature. Conducting the process at temperatures up to 30 °C allowed to eliminate the phenomenon of thermal GO reduction to its non-oxidized form. In addition, based on the Infrared and Raman spectroscopy as well as X-ray photoelectron spectroscopy (XPS) analysis, the cross-linking ability of GO was observed depending on its size and degree of oxidation. These parameters were associated with selected physicochemical and electrical properties of obtained 3D structures. Three GO flakes sizes were tested in three different oxidation degrees. It was shown that, regardless of the size of GO, it is crucial to achieve a specific oxidation degree threshold which for the conducted tests was a >20% share of oxygen atoms in the whole structure. This value determines the ability to cross-link with hydrazine thanks to which it is possible to synthesize the spatial structure in which the π–π interactions among individual flakes are significantly reduced. This directly translates into the fact that the 3D structure shows an electrical resistance value in the range of 4–103 Ω, depending on the size and oxidation degree of the used material. The explanation of this phenomenon related to the electrical conductivity of 3D structures was confirmed based on the molecular modeling of the chemical structures.

Preparation of pH Responsive Polystyrene and Polyvinyl Pyridine Nanospheres Stabilized by Mickering Microgel Emulsions

New pH-sensitive polystyrene, PS, and poly(4-vinylpyridine), P4-VP, nanospheres were prepared by using surfactant-free method based on soft microgels (Mickering emulsion). The formation of stable Mickering cyclohexane/water emulsions was investigated by using soft microgel particles of poly(acrylamide), PAAm, poly(2-acrylamido-2-methylpropane sulfonic acid), PAMPS, and sodium salt of PAMPS, PAMPS-Na, as stabilizers. The dynamic light scattering (DLS), optical microscopy, and scanning electron microscopy (SEM) were used to investigate the optimum conditions and effects of surrounding solutions on the microgels characteristics and their corresponding Mickering emulsions. The cyclohexane/water Mickering emulsions stabilized by softer and neutral charged microgels were considerably more stable under the same conditions. Furthermore, the stimuli-responsive properties of PAMPS microgel stabilized cyclohexane/water Mickering emulsions suggest the potential utility in the preparation of PS and P4-VP nanospheres. The effects of pH changes on the morphology, particle sizes, and surface charges of PS and P4-VP microgels were evaluated to prove the pH-sensitivity of the prepared nanospheres.

An Exploratory Study on the Effect of Petroleum Hydrocarbon on Soils Using Hyperspectral Longwave Infrared Imagery

Manmade crude oil contamination, which has negative impacts on the environment and human health, can be found in various ecosystems all over the globe. Hyperspectral remote sensing (HRS) is an efficient tool to investigate this crude oil contamination where its electromagnetic spectrum is analyzed. This exploratory study used an innovative HRS imagery sensor to study the effect of petroleum hydrocarbon (PHC), found in crude oil, on the spectrum of soils across the longwave infrared (LWIR 8–12 μm) spectral region. This contrasts with previous studies that focused on shortwave and midwave infrared (SWIR 1–2.5 and MWIR 3–8 μm, respectively) regions. An outdoor HRS image of three different types of soils, contaminated with 11 PHC concentrations, was processed and analyzed. Since PHC is spectrally featureless in the LWIR region, the analysis focused on the spectral alteration of the dominant minerals in the soils. Good evaluation metrics of R2 > 0.83 and a root-mean-squared-error (RMSE) between 1.06 and 1.33 wt % showed that the PHC level can be predicted with relatively good accuracy, even without direct spectral features of crude oil PHC, using an airborne LWIR camera in field conditions. This study can be used as a proof of concept for future airborne remote sensing of PHC-contaminated soils.

On the Widths of Bands in the Infrared Spectra of Oxyanions

It is well known that the antisymmetric stretching (ν₃) band in the mid-infrared spectra of oxyanion salts is usually very broad, whereas all the other fundamental bands are narrow. In this paper, we propose that the underlying cause of the increased width is the effect of the very high absorption index of this band for samples prepared with a range of particle sizes. When oxyanion salts are ground, the diameter of the resulting particles usually varies from less than 100 nm to about 2 µm. While the peak absorbance of the ν₃ band of the smaller particles (diameter < 200 nm) is less than 1, that of the larger particles can be as high as 6. We show that the average transmittance of these particles leads to a significant band broadening, especially when there are small voids in the resulting sample. Although the effect is always seen in the spectra of alkali halide disks and mineral oil mulls, it is also seen in diffuse reflection and attenuated total reflection (ATR) spectra. Because the depth of penetration of infrared radiation below 1500 cm^-1 is less than 1 µm for ATR spectra measured with a germanium internal reflection element (IRE), the width of the ν₃ band is lower than that of ATR spectra measured with an IRE of lower refractive index such as diamond on zinc selenide.