Attenuated Total Reflection Research Articles

Thermo-mechanical aging of carbon-black reinforced styrene-butadiene rubber under cyclic-loading

PurposeThe research aims to investigate the impact of thermo-mechanical aging on SBR under cyclic-loading. By conducting experimental analyses and developing a 3D finite element analysis (FEA) model, it seeks to understand chemical and physical changes during aging processes. This research provides insights into nonlinear mechanical behavior, stress softening and microstructural alterations in SBR compounds, improving material performance and guiding future strategies.Design/methodology/approachThis study combines experimental analyses, including cyclic tensile loading, attenuated total reflection (ATR), spectroscopy and energy-dispersive X-ray spectroscopy (EDS) line scans, to investigate the effects of thermo-mechanical aging (TMA) on carbon-black (CB) reinforced styrene-butadiene rubber (SBR). It employs a 3D FEA model using the Abaqus/Implicit code to comprehend the nonlinear behavior and stress softening response, offering a holistic understanding of aging processes and mechanical behavior under cyclic-loading.FindingsThis study reveals significant insights into SBR behavior during thermo-mechanical aging. Findings include surface roughness variations, chemical alterations and microstructural changes. Notably, a partial recovery of stiffness was observed as a function of CB volume fraction. The developed 3D FEA model accurately depicts nonlinear behavior, stress softening and strain fields around CB particles in unstressed states, predicting hysteresis and energy dissipation in aged SBRs.Originality/valueThis research offers novel insights by comprehensively investigating the impact of thermo-mechanical aging on CB-reinforced-SBR. The fusion of experimental techniques with FEA simulations reveals time-dependent mechanical behavior and microstructural changes in SBR materials. The model serves as a valuable tool for predicting material responses under various conditions, advancing the design and engineering of SBR-based products across industries.

High-pressure/high-temperature synthesis of Ln 2CdB5O11(OH) (Ln = Tm, Lu)

Abstract This report presents work on the orthorhombic phases Ln 2CdB5O11(OH) (Ln = Tm, Lu). The title compounds were synthesized in a Walker-type multianvil device at 7 GPa and 650 °C, and the resulting samples were thoroughly investigated through single-crystal and powder X-ray diffraction methods. Lu2CdB5O11(OH) crystallizes in the space group Pmna (no. 53) with the unit cell parameters a = 12.772(2), b = 4.6017(7), and c = 12.481(2) Å. Similar unit cell parameters are observed for the isotypic Tm analogue compound. The crystals have a layered crystal structure built up by four-, five-, and eight-membered rings of corner-sharing [BO4] tetrahedra. The structural data are accompanied by attenuated total reflection (ATR) infrared spectra and energy-dispersive X-ray spectroscopy (EDX).

Stormwater runoff microplastics: Polymer types, particle size, and factors controlling loading rates

Stormwater runoff is a pathway of entry for microplastics (MPs, plastics <5 mm) into aquatic ecosystems. The objectives of this study were to determine MP size, morphology, chemical composition, and loading across urban storm events. Particles were extracted from stormwater samples collected at outfall locations using wet peroxide oxidation and cellulose digestion followed by analysis via attenuated total reflectance (ATR) FTIR. Concentrations observed were 0.99 ± 1.10 MP/L for 500–1000 μm and 0.41 ± 0.30 MP/L for the 1000–5000 μm size ranges. Seventeen different polymer types were observed. MP particle sizes measured using a FTIR-microscope camera indicated non-target size particles based on sieve-size classification, highlighting a potential source of error in studies reporting concentration by size class. A maximum MP load of 38.3 MP/m2 of upstream catchment was calculated. MP loadings had moderate correlations with both rainfall accumulation and intensity (Kendall τ = 0.54 and 0.42, respectively, both p ≤ 0.005). First flush (i.e. rapid wash-off of pollutants from watershed surfaces during rainfall early stages) was not always observed, and antecedent dry days were not correlated with MP abundance, likely due to the short dry periods between sampling events. Overall, the results presented provide data for risk assessment and mitigation strategies.

Raman, ATRIR and NMR spectra, conformational stability, vibrational assignments, normal coordinates analysis and DFT calculations of hydrochlorothiazide drug

The Raman (4000-50 cm−1), attenuated total reflectance (ATR) infrared (4000-400 cm−1) spectra of Hydrochlorothiazide (C7H8ClN3O4S2; HCTZ) have been recorded in the solid state in addition to LCMS in the dimer and trimer ranges. The 1H, 13C and 15N NMR spectra were also recorded in addition to DEPT (45, 90 and 135) of HCTZ sample dissolved DMSO‑d6. Initially, three conformers resulting from the rotation of -SO2NH2 moiety around C9-S11 were proposed, namely gauche, trans and cis conformers. And then Density Functional Theory (DFT) calculations for an isolated molecule were carried out employing both B3LYP and P3PW91 methods at 6-31G(d), 6-311+G(d), 6–311++G(d,p) basis set. The cis isomer is a transition state owing to the prediction of an imaginary wavenumber, while the gauche being more stable than trans by ∼438–538 cm−1 (∼1.25–1.54 kcal) employing the afore-mentioned computations. Moreover, we carried out a potential surface scan for the gauche to determine SO2NH2 barriers to internal rotations and to ensure the optimal gauche is the most stable conformer. Aided by normal coordinate analysis (NCA) in addition to the atomic displacements in Cartesian coordinates (ADCC), confident vibrational assignment of the observed infrared and Raman bands are proposed for all fundamentals of the gauche rotamer. Nevertheless, force constants (FCs) in internal coordinates were also estimated using the above-mentioned methods and basis sets as well. The 1H, 13C and 15N chemical shifts were also correlated to their corresponding atoms. The results are reported herein and compared with HCTZ and its cocrystals whenever appropriate.

Co and Co3O4 in the Hydrolysis of Boron-Containing Hydrides: H2O Activation on the Metal and Oxide Active Centers.

This work focuses on the comparison of H2 evolution in the hydrolysis of boron-containing hydrides (NaBH4, NH3BH3, and (CH2NH2BH3)2) over the Co metal catalyst and the Co3O4-based catalysts. The Co3O4 catalysts were activated in the reaction medium, and a small amount of CuO was added to activate Co3O4 under the action of weaker reducers (NH3BH3, (CH2NH2BH3)2). The high activity of Co3O4 has been previously associated with its reduced states (nanosized CoBn). The performed DFT modeling shows that activating water on the metal-like surface requires overcoming a higher energy barrier compared to hydride activation. The novelty of this study lies in its focus on understanding the impact of the remaining cobalt oxide phase. The XRD, TPR H2, TEM, Raman, and ATR FTIR confirm the formation of oxygen vacancies in the Co3O4 structure in the reaction medium, which increases the amount of adsorbed water. The kinetic isotopic effect measurements in D2O, as well as DFT modeling, reveal differences in water activation between Co and Co3O4-based catalysts. It can be assumed that the oxide phase serves not only as a precursor and support for the reduced nanosized cobalt active component but also as a key catalyst component that improves water activation.

Concentration-Dependent Effects of Curcumin on Membrane Permeability and Structure.

Growing evidence suggests that many bioactive molecules can nonspecifically modulate the physicochemical properties of membranes and influence the action of embedded membrane proteins. This study investigates the interactions of curcumin with protein-free model membranes consisting of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and DOPC with cholesterol (4/1 mol ratio). The focus is on the capability of curcumin to modify membrane barrier properties such as water permeability assayed through the droplet interface bilayer (DIB) model membrane. For pure DOPC, our findings show a concentration-dependent biphasic effect: a reduction in water permeability is observed at low concentrations (up to 2 mol %), whereas at high concentrations of curcumin, water permeability increases. In the presence of cholesterol, we observed an overall reduction in water permeability. A combination of complementary experimental methods, including phase transition parameters studied by differential scanning calorimetry (DSC) and structural properties measured by attenuated total reflectance (ATR)-FTIR, provides a deeper understanding of concentration-dependent interactions of curcumin with DOPC bilayers in the absence and presence of cholesterol. Our experimental findings align with a molecular mechanism of curcumin's interaction with model membranes, wherein its effect is contingent on its concentration. At low concentrations, curcumin binds to the lipid-water interface through hydrogen bonding with the phosphate headgroup, thereby obstructing the transport of water molecules. Conversely, at high concentrations, curcumin permeates the acyl chain region, inducing packing disorders and demonstrating evidence of phase separation. Enhanced knowledge of the impact of curcumin on membranes, which, in turn, can affect protein function, is likely to be beneficial for the successful translation of curcumin into effective medicine.

High-efficient carbon dioxide-to-formate conversion on Bi5O7NO3 by tuning the exposure of crystal plane during reconstruction in electrolysis

The electrochemical conversion of carbon dioxide into formic acid offers an effective approach for utilizing carbon dioxide resources. Bismuth (Bi)-based catalysts have garnered significant attention in this field. However, designing high-performance Bi-based catalysts is challenging due to difficulties in accurately adjusting the reconstruction of such catalysts during electrolysis. In this study, we reported that nitrate ions positively influence the reconstruction of Bi5O7NO3 (BON), thereby outperforming Bi2O3 during ECO2RR. BON attained a Faraday efficiency of formate (FEHCOOH) and partial current density of 95.3 % and 25.1 mA/cm2 at −0.9 V vs RHE, respectively, surpassing the performance of Bi2O3 (90.2 % and 15.4 mA/cm2). The layered structure of BON mitigates Bi agglomeration during electrolysis, thus providing a large number of active sites. The presence of nitrate ions promotes exposure to abundant Bi(110) and Bi(015), whereas only the Bi(012) plane forms in Bi2O3 during electrolysis. In-situ ATR FTIR results indicate that both BON and Bi2O3 follow the same pathway for formate formation. Nevertheless, the high-index planes (015) cause the Bi derived from BON to remain in an electron defect state, which increases the adsorption of *CO2. In addition, Bi(110) plane has effectively lower the energy barriers for *OCHO production than Bi(012) plane. The Bi(015) and Bi(110) planes enhance the adsorption of *CO2 intermediates and reduce the energy barrier for *OCHO formation, respectively, which contributes to the improved ECO2RR activity of BON.

On the textile fibre’s analysis for forensics, utilizing FTIR spectroscopy and machine learning methods

Fibres are prevalent and can be encountered as trace evidence in various situations. In cases of rape and physical assault, analyzing trace fibre components and assessing their transferability can establish connections between individuals and crime scenes or between perpetrators and victims. This study involved Attenuated Total Reflectance – Fourier Transform Infrared (ATR–FTIR) characterization of 104 fibre samples, including natural fibres like cotton and wool (43 samples) and terry wool and synthetic fibres (61 samples). Prominent peaks in different textile fibre spectra were primarily found in the fingerprint region (1800–450 cm−1). To simplify analysis, the spectral data was reduced to principal components, and sample discrimination was performed using Python’s PyCaret package. Multiple machine learning algorithms were explored for differentiating fibre samples, and the most effective one was selected for further validation. This study demonstrates the feasibility of developing an ATR-FTIR database for additional textile fibre samples, aiding in the detection of unknown or suspect fibres in the future.

Nanostructured lipid carrier loaded with Zingiber officinale oil to enhance transdermal bioactive delivery for topical formulation

This study reported on the enhancement of Zingiber officinale (Z. officinale) oil delivery, a bioactive with poor water solubility, by incorporating it into nanostructured lipid carriers (NLC) for transdermal bioactive delivery in topical formulations using the ultrasonication technique with a D–optimal mixture design approach. The independent factors in the process included the percentage of Z. officinale oil, solid lipid (glyceryl monostearate (GMS)), and liquid lipid (virgin coconut oil (VCO)). The study characterized the NLC– Z. officinale oil formulation based on particle size (PS), polydispersity index (PDI), zeta potential (ZP), and encapsulation efficiency (EE) as the dependent variables. Besides, Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy with Attenuated Total Reflection (FTIR–ATR), and Differential Scanning Calorimetry (DSC) were also employed. The optimized NLC–Z. officinale oil formulation, comprising 0.36 % Z. officinale oil, 0.14 % solid lipid (GMS), and 0.50 % liquid lipid (VCO). The study's results demonstrated that the finely tuned NLC– Z. officinale oil formulation, with an average diameter of 90.71 ± 9.48 nm, a PDI of 0.147 ± 0.01, a ZP of –45.7 ± 0.67 mV, and an EE of 88.80 ± 11.18 %, exhibited a controlled and sustained release profile following the Korsmeyer–Peppas model. The in vitro penetration studies on excised Sprague–Dawley rat skin and Strat–M® showcased the heightened penetration flux of NLC–Z. officinale oil compared to Z. officinale oil. Furthermore, in vivo distribution studies in female Sprague–Dawley rats underscored the deep penetration of NLCs into the dermal layer after 12 h of application. Notably, a 3–hour treatment with NLC–Z. officinale oil triggered the release of free fatty acids (FFA). The 90 days storage stability study revealed no significant changes in NLC– Z. officinale oil concerning PS and PDI, affirming its stability over time. These findings illuminated the potential applications of NLC– Z. officinale oil as a robust transdermal bioactive delivery system for Z. officinale oil. This underscored its significance in pharmaceutical formulations, providing a novel avenue for therapeutic purposes.

Preparation of Activated Biocarbons from Cones and their Potential Application for Adsorption of Antibiotics (Tetracycline).

The pine cones (PC), spruce cones (SC) and fir cones (FC) were used for biocarbons preparation. Chemical activation with sodium hydroxide was applied to prepare activated biocarbons. All the materials under investigation were characterized by the N2 adsorption, scanning electron microscopy (SEM), elemental analysis (CHNS), infrared spectroscopy (ATR FT-IR), and the Boehm's titration method. Moreover, pHpzc (the point of zero charge) was determined. It was shown that cones are a good, cheap precursor from which biocarbons with a developed porous structure, characterized by good adsorption properties, can be obtained. All the obtained adsorbents are characterized mainly by a microporous structure. Moreover, they contain both acidic and basic surface functional groups (acidic ones prevail over basic ones). The tested activated biocarbons have large specific surface area values ranging from 578 to 1182 m2 g-1. The efficacy of selected materials in the adsorption of an essential contaminant of increasing concern, tetracycline (TC), was investigated. The experimental data were described using the Langmuir and Freundlich adsorption isotherm models. The maximum adsorption capacity of the tested biocarbons ranges from 200 to 392 mg g-1. Thermodynamic studies proved that adsorption is a spontaneous and endothermic process. In summary, economical and environmentally friendly adsorbents were obtained.

Spatial shifts of reflected rotating elliptical Gaussian beams from surface phonon polaritons in hyperbolic materials

The effect of surface phonon polaritons (SPhPs) on Goos-Hänchen (GH) and Imbert-Fedorov (IF) shifts of reflected rotating elliptical Gaussian beams (REGBs) is investigated in the Otto configuration with a naturally hyperbolic material (NHM) substrate. The spatial shifts are enhanced significantly and adjusted by tuning the REGBs and the optical axis orientation of NHM. The magnitude of GH and IF shifts is easily evaluated by timing the elliptical parameter b02 on the basis of the spatial shift at b0=1.0 when η(=a0/b0)≥2.0. The attenuation total reflection (ATR) spectra are simulated for a hexagonal boron nitride (hBN) substrate. To better understand the impact of SPhPs on the GH and IF shifts, the dispersion curves of SPhPs are calculated. The features of GH and IF shifts around SPhPs can be observed through the frequency scanning along the dispersion curves at a fixed incident angle. The comparison between the ATR spectra and the dispersion curves demonstrates that the enhancement of GH and IF shifts with higher reflection always occurs in the reststrahlen bands (RBs) of NHM once SPhPs are excited. In RB-I, the magnitudes of GH and IF shifts attributable to the SPhPs are located between the peak and dip of a shift curve within a very narrow frequency region. However, in RB-II, the positive maximum values of GH and IF shifts just coincide with the SPhPs. As a result, it is predicted that a relatively large spatial shift will be observed along the frequency scanning line. The large shifts accompanied by the higher reflection may show potential applications in optical or optoelectronic technologies.

Multimodal fiber probe for simultaneous mid-infrared and Raman spectroscopy

A fiber probe has been developed that enables simultaneous acquisition of mid-infrared (MIR) and Raman spectra in the region of 3100–2600 cm−1. Multimodal measurement is based on a proposed ZrO2 crystal design at the tip of an attenuated total reflection (ATR) probe. Mid-infrared ATR spectra are obtained through a pair of chalcogenide infrared (CIR) fibers mounted at the base of the crystal. The probe enables both excitation and acquisition of a weak Raman signal from a portion of the sample in front of the crystal using an additional pair of silica fibers located in a plane perpendicular to the CIR fibers. The advantages of combining MIR and Raman spectra in a single probe have been discussed.

Multimodal Spectroscopic Studies to Evaluate the Effect of Nod-Factor-Based Fertilizer on the Maize (Zea mays) Stem.

Maize (Zea mays) is one of the most cultivated plants in the world. Due to the large area, the scale of its production, and the demand to increase the yield, there is a need for new environmentally friendly fertilizers. One group of such candidates is bacteria-produced nodulation (or nod) factors. Limited research has explored the impact of nodulation, factors on maize within field conditions, with most studies restricted to greenhouse settings and early developmental stages. Additionally, there is a scarcity of investigations that elucidate the metabolic alterations in the maize stem due to nod-factor exposure. It was therefore the aim of this study. Maize stem's metabolites and fibers were analyzed with various imaging analytical techniques: matrix assisted laser desorption ionization-mass spectrometry imaging (MALDI-MSI), Raman spectroscopy, attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR), and diffuse reflectance infrared Fourier transform spectroscopy. Moreover, the biochemical analyses were used to evaluate the proteins and soluble carbohydrates concentration and total phenolic content. These techniques were used to evaluate the influence of nod factor-based biofertilizer on the growth of a non-symbiotic plant, maize. The biofertilizer increased the grain yield and the stem mass. Moreover, the spectroscopic and biochemical investigation proved the appreciable biochemical changes in the stems of the maize in biofertilizer-treated plants. Noticeable changes were found in the spatial distribution and the increase in the concentration of flavonoids such as maysin, quercetin, and rutin. Moreover, the concentration of cell wall components (fibers) increased. Furthermore, it was shown that the use of untargeted analyses (such as Raman and ATR FT-IR, spectroscopic imaging, and MALDI-MSI) is useful for the investigation of the biochemical changes in plants.

Assessment of the efficiency and stability of enzymatic membrane reaction utilizing lipase covalently immobilized on a functionalized hybrid membrane

Enzyme immobilization in membrane bioreactors has been considered as a practical approach to enhance the stability, reusability, and efficiency of enzymes. In this particular study, a new type of hybrid membrane reactor was created through the phase inversion method, utilizing hybrid of graphene oxide nanosheets (GON) and polyether sulfone (PES) in order to covalently immobilize the Candida rugosa lipase (CRL). The surface of hybrid membrane was initially modified by (3-Aminopropyl) triethoxysilane (APTES), before the use of glutaraldehyde (GLU), as a linker, through the imine bonds. The resulted enzymatic hybrid membrane reactors (EHMRs) were then thoroughly analyzed by using field-emission scanning electron microscopy (FE-SEM), contact angle goniometry, surface free energy analysis, X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, attenuated total reflection (ATR), and energy-dispersive X-ray (EDX) spectroscopy. The study also looked into the impact of factors such as initial CRL concentration, storage conditions, and immobilization time on the EHMR's performance and activity, which were subsequently optimized. The results demonstrated that the CRLs covalently immobilized on the EHMRs displayed enhanced pH and thermal stability compared to those physically immobilized or free. These covalently immobilized CRLs could maintain over 60% of their activity even after 6 reaction cycles spanning 50 days. EHMRs are valuable biocatalysts in developing various industrial, environmental, and analytical processes.

Honey differentiation with FTIR-ATR spectroscopy – Comparison with physicochemical parameters of a Polish honey sample set

The varietal discrimination of honey is important because its bioactive properties, as well as specific characteristics, depend on the botanical origin. The present study aimed to verify the discriminatory power of Fourier-transform infrared spectroscopy (FT-IR) for differentiating Polish honeys and compare the results with the discrimination power of a model built on the basis of selected physicochemical parameters. For this purpose, buckwheat, rape, acacia, heather, goldenrod, and coniferous honeydew honeys were collected from trustworthy apiaries in different regions of Poland. The samples were further authenticated using pollen analysis and tested by means of FT-IR and the attenuated total reflection (ATR) technique. Basic psychochemical parameters were also assessed. The obtained data were analyzed by means of principal component analysis (PCA) and linear discriminant analysis (LDA). The obtained models were validated with a leave-one-out cross-validation (LOOCV) procedure. PCA analysis confirmed the usefulness of the ATR FT-IR method as a honey differentiation tool. The LDA for the FT-IR model allowed to correctly classify 26 out of 32 samples (81.3% accuracy), which was only slightly lower than for data the model based on the physiochemical characteristics (27 out of 32 samples and 84.4% accuracy), revealing a certain potential of FT-IR as fast evaluation method.

Preconcentration and Removal of Lead From Water Samples Using Magnetic Copper Ferrite Nanoparticles

The presence of lead and its compounds is extremely dangerous to various forms of life. Therefore, exploring effective treatments that can reduce the presence of lead ions around us becomes crucial, thereby averting lead toxicity. A magnetic solid phase extraction (MSPE) procedure for the removal and preconcentration of trace amounts of Pb(II) using copper ferrite nanoparticles (CuFe2O4 NPs) prior to their determination by flame atomic absorption spectrometry (FAAS) has been proposed. CuFe2O4 as solid-phase extraction adsorbent was synthesized via co-precipitation and characterized by attenuated total reflection–infrared spectroscopy (ATR–IR), x-ray diffraction spectrometry (XRD), and scanning electron microscopy (SEM). These magnetic CuFe2O4 carrying the Pb(II) could be easily separated from the aqueous solution by applying an external magnetic field; no filtration or centrifugation was necessary. Various analytical parameters, including pH, eluent type/concentration, adsorbent mass, sample volume, adsorption/desorption time, mixing, and interfering ions, were systematically studied and optimized for the recovery of Pb(II). A sample volume of 20 mL achieved a preconcentration factor of 20. The method effectively determined Pb(II) in water samples, with recovery values exceeding 95% using the optimal conditions.

Advancements in Cotton Textile Design: Addressing Temperature and Moisture Challenges

The primary objective of this study is to alleviate discomfort arising from fluctuations in heat and humidity due to environmental and personal factors, aiming to develop functional textiles capable of effectively responding to these changes. To achieve this, systematic pattern designs were implemented on 100% cotton woven fabrics, incorporating hydrophobic characteristics through the application of a water-repellent agent to specific areas. The resulting compatibility of these hydrophobic features with hydrophilic elements endowed the fabrics with moisture management properties. Furthermore, the introduction of a phase-changing material agent to these fabrics imparted heat management capabilities. The rotation printing technique was employed to seamlessly transfer these agents onto the fabric. In assessing the durability of woven fabrics featuring distinct functionalities, a comprehensive examination was conducted, subjecting them to 30 repeated wash cycles within a single process step. The morphological structures of the fabrics produced were meticulously analyzed using SEM (scanning electron microscopy), SEM–EDX (energy-dispersive X-ray analysis) while their chemical compositions were scrutinized through FTIR–ATR (Fourier transform infrared spectroscopy–attenuated total reflectance). Additionally, a battery of tests, including physical, chemical, liquid absorption, liquid transfer assessments, and DSC (differential scanning calorimetry) analyses, were conducted in accordance with relevant standards. The outcomes of this study demonstrated that the fabrics not only met the criteria of the TS 866 standard, particularly with regard to a rapid response time of less than 10 s, but also exhibited resilience to repeated washings, affirming the enduring efficacy of the incorporated functionalities. According to tearing strength results, slight increase was also observed in treated cotton fabrics.

Silica-Containing Phosphorus-Based Sol-Gel Finishing to Improve Flame Retardant Performance of Cotton Fabrics

In this paper, the sol-gel technique was used to design hybrid phosphorus-doped silica structures for improving the thermal stability and flame retardancy of cotton fabrics. To this aim, diethylphosphatoethyltriethoxysilane (DPTS) was employed as phosphate alkoxysilane in a multistep procedure that involved multiple layers (from 1 to 6) depositions. The multi-layer coatings were applied by padding using sols containing appropriate molar ratios of the precursor, anhydrous ethanol, catalyst, and hydrochloric acid. Moreover, the synergism P-N on flame retardancy of cotton was assessed by introducing 3-aminopropyltriethoxysilane (APTES) as an N-donor precursor in DPTS sols. The effects of the catalyst during the alkoxide reaction and the silica amount applied by sol-gel treatment on the thermo-oxidative behavior of the treated fabrics were deeply studied. The creation of the silica skeleton on the cotton surface and the interactions between the cellulosic fibres and the doped layer were investigated using FT-IR ATR spectroscopy. Moreover, thermal and thermo-oxidative stability, flammability properties, and combustion behavior of the sol-gel treated cotton fabrics were also studied, proving the effectiveness of the sol-gel coating in the fire protection of the cellulosic substrate.

Rapid classification of epidemiologically relevant age categories of the malaria vector, Anopheles funestus

BackgroundAccurately determining the age and survival probabilities of adult mosquitoes is crucial for understanding parasite transmission, evaluating the effectiveness of control interventions and assessing disease risk in communities. This study was aimed at demonstrating the rapid identification of epidemiologically relevant age categories of Anopheles funestus, a major Afro-tropical malaria vector, through the innovative combination of infrared spectroscopy and machine learning, instead of the cumbersome practice of dissecting mosquito ovaries to estimate age based on parity status.MethodsAnopheles funestus larvae were collected in rural south-eastern Tanzania and reared in an insectary. Emerging adult females were sorted by age (1–16 days old) and preserved using silica gel. Polymerase chain reaction (PCR) confirmation was conducted using DNA extracted from mosquito legs to verify the presence of An. funestus and to eliminate undesired mosquitoes. Mid-infrared spectra were obtained by scanning the heads and thoraces of the mosquitoes using an attenuated total reflection–Fourier transform infrared (ATR–FT-IR) spectrometer. The spectra (N = 2084) were divided into two epidemiologically relevant age groups: 1–9 days (young, non-infectious) and 10–16 days (old, potentially infectious). The dimensionality of the spectra was reduced using principal component analysis, and then a set of machine learning and multi-layer perceptron (MLP) models were trained using the spectra to predict the mosquito age categories.ResultsThe best-performing model, XGBoost, achieved overall accuracy of 87%, with classification accuracy of 89% for young and 84% for old An. funestus. When the most important spectral features influencing the model performance were selected to train a new model, the overall accuracy increased slightly to 89%. The MLP model, utilizing the significant spectral features, achieved higher classification accuracy of 95% and 94% for the young and old An. funestus, respectively. After dimensionality reduction, the MLP achieved 93% accuracy for both age categories.ConclusionsThis study shows how machine learning can quickly classify epidemiologically relevant age groups of An. funestus based on their mid-infrared spectra. Having been previously applied to An. gambiae, An. arabiensis and An. coluzzii, this demonstration on An. funestus underscores the potential of this low-cost, reagent-free technique for widespread use on all the major Afro-tropical malaria vectors. Future research should demonstrate how such machine-derived age classifications in field-collected mosquitoes correlate with malaria in human populations.Graphical

Near-unity nonreciprocal thermal radiation in biaxial van der Waals material-Weyl semimetal heterostructures

Polaritons in natural van der Waals (vdW) materials have drawn significant attention as the unique optical properties and have opened doors for various potential applications. α-phase molybdenum trioxide (α-MoO3) has been revealed as a semiconducting anisotropic vdW material that holds great promise for manipulating orthogonal in-plane phonon polariton (PhP) modes in infrared (IR). Here, we consider an attenuated total reflection (ATR) geometry consisting of an α-MoO3 layer and a Weyl semimetal (WSM) interlayer sitting on a silver (Ag) substrate. The incorperated coupling prism is selected as KRS5 (thallium bromide-iodide) that can provide a larger wavevector. The spectral responses of the proposal have been investigated using electromagnetic (EM) simulations that utilize the anisotropic rigorous coupled-wave analysis (aRCWA). Our results demonstrate that the α-MoO3 thin layer can boost the constrast between the emissivity and absorptivity in a broad range of wavelength as compared to an uncoated device. The nonreciprocity at resonance wavelength can reach near-unity for both transverse electric (TE) and transverse magnetic (TM) wave incidence. The proposed α-MoO3/WSM heterostructure suggests great potentials for thermal radiation management with different demands.