Attenuated Total Reflection Research Articles

Fourier Transform Infrared Spectroscopy (FTIR) for identification of sugar adulterants in mulberry molasses (pekmez)

Fourier Transform Infrared Spectroscopy (FTIR) and chemometrics were successfully used in this research in conjunction with the Attenuated Total Reflectance (ATR) technique to determine bulberry molasses (MM) canesugar adulteration. Mulberry molasses was adultered by incorporating two fructose syrups (FS), one glucose syrup (GS), one sucrose syrup (SS), and two specific high fructose corn syrups (HFCS). Calibration sets were developed for mulberry molasses by spiking sugar syrups. The actual percentage of adulteration linked to FTIR predicted results by partial least square (PLS). The preferred spectral range was 1184-944 cm-1 for prediction of adulteration levels of F20, F30, HFCS50, HFCS55 and 1090-950 cm-1 for sucrose. This method was employed to distinguish between mulberry molasses and adulterated samples. According to the findings, the FTIR technique is an accurate and affordable method that can rapidly detect sugar adulteration in mulberry molasses.

Effect of 4,4′-dialkyl-2,2′-bipyridine ligands on the hydrolysis of dichlorodioxomolybdenum(VI) catalyst precursors and the switch from homogeneous epoxidation to heterogeneous systems

Molybdenum catalysts have been industrially recognized for decades for liquid phase epoxidation, which is an important chemical reaction process, since epoxides are used for many industrial applications. In this work, molybdenum oxide hybrid catalysts, prepared by a reflux hydrolysis methodology, performed effectively as heterogeneous catalysts or reaction-induced self-separating catalysts under mild reaction conditions; in the two cases, the catalyst separation and reuse are facilitated. Specifically, catalysts with the general formula [MoO3(L)], possessing polymeric chain-like (L = 4,4′-dimethyl-2,2′-bipyridine (1)) or oligomeric (L = 4,4′-dinonyl-2,2′-bipyridine (2)) structures comprising corner-sharing {MoO4N2} units, were synthesized and characterized by various complementary techniques (ATR FT-IR, Raman, 13C{1H} CP MAS NMR spectroscopy, PXRD, SEM, TGA, elemental analysis, ICP-OES and N2 sorption isotherms). Small chemical differences in the organic synthesis precursor had important structure directing effects on the type of hybrid material formed. The hybrids promoted olefin epoxidation with H2O2 or tert-butylhydroperoxide (TBHP) as oxidant. For example, 1 catalyzed the conversion of biobased olefins (70 °C) and lignin-based isoeugenol (50 °C) with TBHP to useful bioproducts, in heterogeneous phase, leading to an epoxide yield of 100 % for DL-limonene (3:1 M molar ratio of 1,2-epoxy-p-menth-8-ene to 1,2:8,9-diepoxy-p-menthane), 81 % epoxide yield for fatty acid methyl esters, and 80 % Licarin A selectivity at 40 % isoeugenol conversion. For dienes (DL-limonene, methyl linoleate), kinetic modelling studies suggested that the formation of the monoepoxides was faster than that of diepoxides, accounting for enhanced monoepoxide selectivity.

Measurement of tyre-based microplastics using traditional and quantum cascade laser-based infrared spectrometry

BackgroundDespite the potential environmental impact of TWPs (tyre wear particles), there is a lack of reliable analytical methodologies suitable for their routineidentification and characterization. The number of papers dealing with this topic is, so far, very reduced and, therefore, there is a need for addressing it, mostly because traditional transmittance-based IR techniques are suboptimal due to scattering caused by black carbon in tyres. ResultsThis study aims to evaluate the most appropriate infrared (IR) spectrometric technique for monitoring TWPs. Macro attenuated total reflectance (ATR), reflectance microscopy, and quantum cascade laser-based micro transflectance (QCL-LDIR) were employed to analyse samples from used car and truck tyres in two sample configurations: small tyre fragments (∼1 cm2) and TWPs (< 1 mm). ATR yielded well-defined spectra with good signal-to-noise ratios, allowing for a straightforward interpretation of the major functional moieties. Despite reflectance measurements on tyre fragments provided good results, those on TWPs offered limited information due to noise and scattering. Transflectance offered clear peaks and enhanced resolution in the fingerprint region –compared to the other techniques-, much faster analysis times and the ability to effectively measure particles down to 20–10 µm, thus, emerging as the most effective technique for TWPs analysis. However, spectral interpretation is not immediate. Further, a proof-of-concept study was done to evaluate whether the analytical techniques contain information to differentiate types of tyres. An unsupervised pattern recognition and a supervised classification technique (principal components analysis and classification trees, CART) were used, which were able to differentiate among the tyres, notably the truck tyre from the cars tyres. SignificanceThe study presents first time the use of micro transflectance IR to study tyre particles down to 20 µm. Traditional total attenuated reflectance is demonstrated as a suitable way to analyse bigger microplastics. These two options open pathways to monitor this important emerging contaminant in environmental matrices

Antioxidant films loaded with β-cyclodextrin-quercetin for enhancing food preservation

As the improvement of consciousness of environment, a considerable effort has been made to shift from petroleum-based plastics to biodegradable alternatives, especially in the food packaging industry. In this work, we develop an innovative food packaging film by encapsulating quercetin (Que) within β-cyclodextrin (β-CD) to create β-CD-Que inclusion complexes, which are then dispersed in a matrix of tragacanth gum (TG) and carboxymethyl chitosan (CMCS) using a solution casting technique. β-CD-Que inclusion complexes were characterized using various methods, including 1H NMR, 2D ROESY and phase solubility testing, to elucidate the interaction between Que and β-CD. ATR–IR, X-ray diffraction, and SEM were employed to confirm the uniform dispersion of β-CD-Que within the macromolecular substrate. The incorporation of β-CD-Que considerably improves the mechanical properties of films, increasing the elongation at break from 13.68 % to 25.74 %. Rheological tests demonstrate that the viscosity of the film-forming complex solution became larger. The films were demonstrated to reduced water vapor and oxygen permeability, possessing remarkable antioxidant capability evidenced by DPPH and ABTS radical scavenging rates of 78.01 % and 99.59 %, respectively. The TG/CMCS/β-CD-Que composite film shows excellent potential for food packaging and preservation applications.

A new approach to assess post-mortem interval: A machine learning-assisted label-free ATR-FTIR analysis of human vitreous humor

A crucial issue in forensics is determining the post-mortem interval (PMI), the time between death and the finding of a body. Despite various methods already employed for its estimation, only approximate values are currently achievable. Vitreous humor (VH) is an avascular tissue between the lens and the retina, mainly composed by a collagen fibers network, hyaluronic acid, and hyalocytes. Recently, it has received interest in forensic medicine, being easy to collect and susceptible to low microbiological contamination and putrefaction. Based on this evidence and thanks to the ability of Attenuated Total Reflectance – Fourier Transform InfraRed (ATR–FTIR) spectroscopy to perform fast analyses on a minimal sample amount, in this study, a new analytical approach to reliably estimate PMI is proposed combining ATR-FTIR analysis of VH human samples with multivariate statistical procedures, such as Principal Component Analysis (PCA) and Partial Least Squares-Discriminant Analysis (PLS-DA), for discriminant classification. Regression procedures, including Partial Least Squares Regression (PLSR), were performed: extremely positive results were obtained, and the most discriminant spectral features were highlighted (peaks at 1665, 1630, 1585, 1400, 1220, 1200, 1120, 854, 835, and 740 cm−1) and associated to PMI classes (average accuracy over 80 %). Specific and reliable markers able to correlate the macromolecular composition of VH with the PMI were identified, revealing a post-mortem protein degradation and amino acids deamination (decrease of proteins and increase of free amino acids and NH3), an increase of lactate, which diffuses from the retina to the VH, and changes in the hyaluronic acid component.

Идентификация цефалоспориновых антибиотиков с использованием ИК-спектроскопии и хемометрических алгоритмов

The use of mid-field infrared spectroscopy in combination with chemometric algorithms for the identification of cephalosporin antibiotics in the form of injectable powders is demonstrated. III generation cephalosporins have been selected as objects of the study: ceftriaxone, ceftazidime, cefotaxime, which are widely used in pharmaceutical practice. IR spectra of the medical preparations have been recorded using an FT-801 Fourier transform IR spectrometer with an attenuated total reflection (ATR) attachment. The results have been processed in the Microsoft Excel computer package with the XLSTAT add-in using the principal component analysis (PCA), the k-means method and agglomerative hierarchical clustering (AНC). It has been shown that using these algorithms it is possible to identify the studied cephalosporin antibiotics from different manufacturers. In the PCA method, points corresponding to samples are located in separate quadrants depending on the nature of the antibiotic. The k-means method has been used to divide antibiotics into classes; differences are also visible in the classes themselves, depending on the manufacturer. The clearest separation of cephalosporins is observed when data are presented using the AHC method in the form of a dendrogram.

Two-Dimensional Correlation Spectroscopy (2D-COS) Tracking of the Formation of Selected Transition Metal Compounds Cu(II) and Cd(II) With Cinchonine and Their Impact on Model Components of Erythrocytes.

Cinchonine is a quinoline alkaloid known for its antimalarial properties. Due to the advantages of using compounds of metal ions with alkaloids, a copper(II) compound with cinchonine was synthesized, and, for comparative purposes, a cadmium(II) compound with cinchonine. During the synthesis, the emerging interactions between the metal ion and cinchonine were studied. After crystallization, it was examined how the obtained compounds would interact with the model blood component, hematoporphyrin IX. Ultraviolet-visible (UV-Vis) spectroscopy, Raman spectroscopy, and attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR) were used in the study. In the case of monitoring the synthesis, the best method turned out to be UV-Vis spectroscopy, combined with the possibility of two-dimensional correlation spectroscopy (2D-COS), which enabled the identification of peaks characteristic of the interactions of the cinchonine quinoline ring with metal ions. In turn, the obtained Raman spectra showed shifts of individual bands and changes in their intensity, and 2D-COS showed the sequence of formation of individual interactions, which confirmed the formation of cinchonine compounds with metals. ATR FT-IR also allowed us to compare the spectra of the substrates used in the synthesis with the crystallized compounds and thus confirm the formation of the expected compounds. Bands characteristic of π-π-stacking interactions between the quinoline ring and the tetrapyrrole ring of hematoporphyrin IX were also observed. Observed interaction with a model blood component may be important when designing drugs for antimalarial therapy.

Fourier transform infrared spectroscopy coupled with multivariate calibration for determination of carmine and rhodamine B levels in lipstick

Carmine is a natural colorant allowed to be used in cosmetics, while rhodamine is nonallowable. For some reason, carmine may be substituted with rhodamine to get economic profits. Therefore, some analytical methods are proposed and developed. This study developed fourier transform infrared (FTIR) spectroscopy in conjunction with utilizing multivariate calibration to determine carmine (CAR) and rhodamine B (RHB) levels in lipstick samples. Lipstick samples were placed directly into an attenuated total reflectance (ATR) crystal and scanned in the 4,000-650 cm-1 wavenumber range. The CAR and RHB levels were also determined using HPLC to be used as actual values. Partial least squares regression (PLSR) was used to stimulate the correlation between actual CAR and RHB values and predicted FTIR values. Based on optimization in terms of the selection of wavenumbers region, for CAR and RHB prediction modeling, absorbance values at wavenumbers of 1,357-673 cm-1 were used. The developed methods, besides having high validity, are rapid and exclusive of extensive solvents with minimum sample preparation; therefore, this technique is environmentally friendly

A comprehensive study of optical resonances in metals, dielectrics, and excitonic materials in double interface structures

From an optical perspective, depending on the relationship between the real (n) and imaginary (k) parts of its refractive index, three broad categories of materials can be distinguished: metals (k ≫ n), dielectrics (n ≫ k), and materials in which n ≈ k (termed here excitonic materials). The modes and optical resonances that appear in a thin film bounded by two dielectrics with similar refractive index, what we call here a double interface structure, have been widely studied in the case of metals, but not for dielectrics, or materials with n ≈ k. In this work, we propose a new approach, based on employing the phase matching condition to correlate the resonances that appear in the wavelength versus incident angle color maps of the reflected power with the modal analysis of the cross section of the structure. This analysis is performed, using an attenuated total reflection (ATR) setup, for thin film materials that belong to each of the mentioned categories: a metal (gold, Au), a dielectric (titanium dioxide, TiO2), and a material with n ≈ k (chromium, Cr). The theoretical analysis is supported with experimental results. It is demonstrated that this method enables to identify any resonance at any wavelength or incident angle, being valid for all three types of materials. Therefore, it is considered the suggested approach will help the research in these materials and in the double interface structure in the optics and photonics field.

Detection of Verticillium infection in cotton leaves using ATR-FTIR spectroscopy coupled with machine learning algorithms

Verticillium wilt (VW) is a soil-borne vascular disease that affects upland cotton and is caused by Verticillium dahliae Kleb. A rapid and user-friendly early diagnostic technique is essential for the preventing and controlling VW disease. In this study, Fourier transform infrared (FTIR) spectroscopy with attenuated total reflectance (ATR) technology was used to detect VW infection in cotton leaves. About 1800 FTIR spectra were obtained from 348 cotton leaves. The cotton leaves were collected from three categories: VW group, infected group and control group (non-infected). The vibrational peak of chitins at 1558 cm−1 was identified through mean and differential analysis of FTIR spectra as a criterion to differentiate the VW or infected group from the control group. Classification models were constructed using various machine learning algorithms. The support vector machines (SVM) model exhibited the highest predictive accuracy (>96 %) in each group and a total accuracy (>97 %) for the three groups. These results provide a new approach for detecting Verticillium infection in cotton leaves and shows a promising potential for the future applications of the method in plant science.

Surface chemistry and catalytic activity in H2O2 decomposition of pyrolytically fluoralkylated activated carbons.

According to the proposed pyrolytic method, granular activated carbon (AC) Norit 830 W was functionalized by thermal treatment of AC in hydrofluorocarbon (HFC) gases, pentafluoroethane and 1,1,1,2-tetrafluoroethane, at 400-800 °C. This method does not require activation by plasma and photons. Chemical and elemental analysis showed that the pyrolytic treatment provides a loading of 2.95 mmol (5.6 wt%) of fluorine per gram of AC. Nitrogen adsorption measurements indicated that the microporous structure contracted when AC was treated with HFC at temperatures above 400 °C. Thermogravimetry, Fourier transform infrared spectroscopy (FTIR) with attenuated total reflectance (ATR), and X-ray photoelectron spectroscopy (XPS) demonstrated the evolution of oxygen-containing and fluorine-containing groups to more thermostable groups with treatment temperature. The fluorine-containing groups grafted at high temperature, above 600 °C exhibited the highest thermal stability up to 1250 °C in dry argon. From the data of XPS and solid-state 19F nuclear magnetic resonance spectroscopy data, the grafted fluorine exists in several types of grafted F-containing groups, the HFC residues. By changing the thermal regime of fluorination, the composition of fluorine-containing groups on a carbon surface can be regulated. Isolated fluoroalkyl groups can be grafted at temperatures of 400-500 °C, while at 600 °C and above, the semi-ionic fluorine groups increase significantly. The hydrophobized surface demonstrated the ability to effectively decompose H2O2 in methanol solutions.

Optical Based Surface Plasmon Resonance Sensor for the Detection of the Various Kind of Cancerous Cell.

This research explores a novel biosensor design that exhibits much higher sensitivity compared to conventional biosensors. The biosensor's uniqueness originated from its innovative structure, which incorporates N-FK51A/Ag/AlON/BlueP materials, as well as its cutting-edge fabrication method. The refractive index component was considered when designing the SPR biosensor, which was developed from the angular analysis of the attenuated total reflection (ATR) approach for cancer detection. For instance, the resonance angle shifts by 15.57 deg when the refractive index changes from 1.360 to 1.401, demonstrating the sensor's responsiveness to variation in the refractive index. The sensitivities for skin (basal), cervical (HeLa), blood (Jurkat), adrenal gland (PC12), and breast (MDA-MB-231 and MCF-7) cancer cells were 197.65, 243.66, 255.36, 302.71, 372.57, and 416.85 deg/RIU, respectively. Also, the detection accuracy (DA), the figure of merit (FoM), and the quality factor were 0.37/deg, 155.94 (deg/RIU), and 26.71 RIU-1. We also examine the effects of substituting the noble, dielectric, 2D material layer with conventional biosensor materials for six cancers. Each time, the Ag/AION/BlueP layered structure performed best in distinguishing cancer cells from healthy cells. We also study the prism effects. The proposed biosensor, with a RI of 1.29-1.40, has a linear regression coefficient of R2 of 0.96094.

Novel biophysical skin biomarkers discriminate topical anti‐inflammatory treatments based on their potential for local adverse effects

AbstractBackgroundTopical corticosteroids (TCS) are efficacious treatments for inflammatory skin conditions, however, there is a risk of adverse effects; understanding how best to use these treatments is an unmet research priority shared by patients and healthcare professionals.ObjectivesTo develop non‐invasive biomarkers of local adverse effects to facilitate the optimisation of topical therapy.MethodsAn observer‐blind randomised within‐subject controlled trial in atopic dermatitis patients was undertaken (NCT04194814) comparing betamethasone valerate 0.1% cream (BMV) to a non‐steroidal anti‐inflammatory treatment, crisaborole 2% ointment (CRB). Participants underwent 4 weeks twice‐daily treatment with CRB on one forearm and BMV on the other (left/right randomised). Skin properties were assessed on days 1, 15, 29 of treatment and again on day 57, including imaging of skin microstructure using Optical Coherence Tomography (OCT) and Attenuated Total Reflectance (ATR)‐Fourier Transform Infrared (FTIR) spectroscopic assessment of stratum corneum molecular structure. The primary outcome was the difference in the change in epidermal thickness from days 1 to 29.ResultsThirty‐seven participants received the first dose, of which 32 completed the study (all 37 were included in the analysis). Pathologic epidermal thinning at day 29 was significantly greater (p &lt; 0.0001) at sites treated with BMV (−31.66; 95% confidence interval: −35.31, −28.01 µm) compared to CRB (−13.76; −17.42, −10.10 µm). From a panel of exploratory biomarkers, superficial plexus depth and stratum corneum carboxyl group levels had the greatest ability to discriminate the effects of the TCS treatment (p &lt; 0.0001).ConclusionsBMV induced 2.3x more pathologic epidermal thinning than CRB after 4 weeks of treatment, suggesting that CRB may be more appropriate for longer‐term, proactive‐based, treatment strategies where the risks of adverse effects are greatest. By monitoring treatment effects using OCT and ATR‐FTIR spectroscopy, two new non‐invasive biomarkers of skin health have been identified with the potential to help optimise future safe treatment strategies.

Determining aqueous deuterium detection limits via infrared spectroscopy to understand its capabilities for real-time monitoring of tritiated water

Tritiated water will be present in many demonstrator class fusion devices in a wide array of locations and concentrations. Accurate and fast measurement will be a key requirement to ensure suitable process monitoring, safety assurance and tritium tracking is in place. This work quantifies the deuterium detection limits achievable using a benchtop transmission Fourier transform infrared (FTIR) instrument and an industrialised attenuated total reflectance (ATR)-FTIR instrument to understand the capabilities of these techniques for real-time monitoring of aqueous tritium. Deuterium limits of detection of 4.62 × 10-5 mol mL-1 and 1.07 × 10-3 mol mL-1 were demonstrated with measurement times of 10s for the transmission FTIR and ATR-FTIR, respectively. These instruments are considered viable for the measurement of high concentration tritiated water and have many potential benefits associated with their deployment.

Investigating the effect of gliding discharge plasma on polystyrene and Polyamide6 by positron annihilation lifetime spectroscopy

Polymers are widely used today and the changes in their properties are investigated by different methods such as plasma irradiation. One of the most important methods for modifying polymers is cold plasma, by which the surface properties of the polymers can be changed under atmospheric pressure. In this study, the effect of plasma on Polystyrene (PS) and Polyamide 6 (PA6) samples was investigated. Surface and depth changes of the PS and PA6 have been investigated by various experimental techniques such as Fourier Transform Infrared (FTIR), X-ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), Contact Angle (CA), and Positron Annihilation Lifetime Spectroscopy (PALS). The results of Attenuated Total Reflectance (ATR)-FTIR show that the chemical bonds of PA6 have been changed, and preserved in PS in the depths. The XRD results show that there are no volume changes for chemical bands. The FESEM analysis results reveal that the plasma causes digging and creates roughness on the surface. The CA measurement confirms the FESEM results and points out an increase in hydrophobicity after plasma processing. The PALS results indicate that the free volumes of the matter are changed after plasma irradiation in the depths of PS and PA6. In addition, the plasma also causes changes in the micrometer depth.

Effect of Photoaging on the Structure, Optical Properties and Roughness of One-Shade Composite Restoratives.

The aim of the study was to evaluate changes in the degree of C=C conversion (DC%), chemical structure, optical properties and roughness of one-shade composites before/after photoaging. Τhe one-shade materials tested were Charisma Topaz One (CHT), Clearfil Majesty ES-2 Universal (MES), Essentia Universal (ESU) and Omnichroma (OMN), with G-aenial Anterior (CNA) serving as control. Specimens (2 mm thickness) were prepared and tested for DC% and chemical structure (ATR-FTIR spectroscopy), optical properties (L*a*b*-ΔΕ, translucency parameter-TP, opalescence parameter-OP, contrast ratio-CR and total transmittance-TT by UV-Vis spectroscopy) and roughness (Sa, Sz, Sdr, Sds and Sc by optical profilometry) before and after photoaging (Xe-arc weatherometer). Significant differences were found in DC% between top-bottom surfaces (ESU, OMN before; ESU, CNA after). Photoaging improved DC%, reduced ester peaks implying photodegradation, reduced L* (CHT, OMN, CNA), a* (CHT, CNA), b* (OMN, CNA), TP (all, except for MES), OP (only MES), CR (only MES, but an increase in CNA) and TT (CHT, OMN). OMN, CNA and MES demonstrated ΔΕ > 3.3. Photoaging significantly increased all roughness parameters in all materials, except for MES (Sz, Sdr, Sc) and OMN (Sdr). Although listed in the same group, significant differences were found in one-shade composites before and after photoaging. Several products were strongly affected by photoaging, demonstrating evidence of photodegradation, an increased roughness and color changes exceeding the clinically acceptable levels.

Influence of Preheating Self-Adhesive Cements on the Degree of Conversion, Cell Migration, and Cell Viability

Enhancing the degree of polymerization can mitigate the cytotoxic effects of resinous materials, as residual monomers have been identified as a significant contributor to cytotoxicity. Hence, the aim of the current research was to evaluate the influence of preheating self-adhesive cements at 39 °C on cell migration, cytotoxicity, and degree of conversion. RelyX U200, Set PP, and MaxCem Elite were subjected to Fourier Transform Infrared Spectroscopy–Attenuated Total Reflection (FTIR–ATR). Self-adhesive resin cements were applied onto an ATR device, with samples subjected to either heated or room temperature conditions, followed by photoactivation. For the cytotoxicity analysis, extracts (24 h and 7 days) were placed in contact with NIH/3T3 cells. For cell migration, images were captured of each sample until the possible closure of the cleft occurred. A two-way analysis of variance (ANOVA) was conducted to assess the effect of preheating on the degree of conversion and cell viability within the self-adhesive cements tested. A significance level of 5% was set for statistical purposes. In the results of the degree of conversion, preheating did not improve the conversion of cements (p &gt; 0.05). For the 3-(4-5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT), preheating did not improve the results within 24 h, however, it generated positive results within 7 days for the Set PP resin cement (p &lt; 0.05). For cell migration, high rates of cell death were found in all groups. It is concluded that preheating at 39 °C causes a positive effect only in increasing the cell viability of the Set PP resin cement and that both materials analyzed are highly cytotoxic.

Determination of Bioactive Compounds in Buriti Oil by Prediction Models Through Mid-infrared Spectroscopy

Buriti oil is a vegetable oil extracted from the pulp and seeds of buriti (Mauritia flexuosa L.), a palm commonly found in the Amazon region, and is used both in popular medicine and in the cosmetic and food industries. This work aimed to develop a faster and more accessible procedure to quantify the content of carotenoids, polyphenols, and total flavonoids in buriti oils, where predictive models emphasize figures of merit. The study was carried out with 50 buriti oil samples from the state of Pará, Brazil, which were sampled by combining attenuated total reflection (ATR) spectroscopy with mid-infrared Fourier transform (FT-MIR) together with partial least squares regression (PLSR). The confidence and validation matrix were obtained from ultraviolet–visible spectroscopy. The PLSR model regarding the total carotenoid content presented values ​​between 335.33 and 1557.05 μg/g was validated by the concentration demonstration coefficient (R2cal) equal to 0.9556, prediction demonstration coefficient (R2pred) equal to 0.85642, bias = 5.68.10−13, performance deviation ratio value (RDP) of 2.0135, and range error rate (RER) equal to 4.3747. Concentrations of phenolic compounds were predicted between 96.2964 and 121.857 GAE/100 g, where the model presented R2cal = 0.9762, R2pred = 0.8198, bias = 3.38.10−10, RDP = 5.9028, and RER = 5.7578. The flavonoid prediction model contains concentrations between 86.844 and 133.852 mg EC/100 g that circulate R2cal = 0.9445, R2pred = 0.8536, bias = 6.98.10−8, RDP = 6.7085, and RER = 6.7085. Buriti oil showed high levels of b-carotene. Prediction models are overwhelming and can be used for screening and quality control of natural products.

Rheological performance regulation of solidified soil slurry for mine reclamation: Superplasticizer selection and structural characterization based on in-situ techniques

This paper focuses on the low cement content characteristic of soil slurry materials for mine reclamation, investigating the effects of three types of superplasticizers (polyester-based polycarboxylate (PCE), sodium lignosulfonate (SLS), and naphthalene-based (PNS)) on the flow properties of freshly mixed solidified soil slurry. It proposes a method combining shear rheology and micro-rheology experiments to complete the selection of superplasticizers. The rheological properties of the freshly mixed slurry were compared at different dosages of superplasticizers and various resting times. The results indicate that PCE at 0.4 % dosage exhibits the best dispersion effect in the solidified soil slurry. In-situ ATR FTIR, in-situ low-field NMR, and ζ-potential tests confirmed that PCE can effectively delay the solidification process of the soil slurry to maintain its fluidity. At a PCE dosage of 0.4 %, the spatial hindrance between slurry particles is reduced, increasing the proportion of “free water” in the solidified soil, with the ζ-potential not being the main factor affecting the rheological properties of the soil slurry. This study provides a theoretical foundation and solutions for regulating the early fluidity of solidified soil slurry materials used in the land reclamation of coal gangue in the Northwest mining areas of China.

Enhancement of Solubility and Dissolution Rate of Simvastatin Tablets by Liquisolid Compact Approach

The aim of the current work was to improve the solubility and dissolution rate of poorly water-soluble drug, simvastatin (SM) by using the liquisolid compact technique (LS; SM-LS). Liquid load factors, and excipient ratios were used to calculate the required amounts of excipients necessary to prepare the SM-LS and compressed to tablets according to mathematical models. Avicel PH102, Aerosil 200 and Crosspovidone (CP) was used as carrier, coating material and disintegrant, respectively. Drug-excipient mixtures were evaluated compatibility by Attenuated total reflectance (ATR) and differential scanning calorimetry (DSC). Prepared SM-LS formulations were evaluated for various pre-compression and post-compressional parameters, in-vitro dissolution, and stability studies (40 ± 2°C / 75 ± 5% RH) for 3 months. Among the different formulations, LS10 formulation which contains 30% drug, 5% CP, Avicel pH 102: Aerosil 200 (1:10) showed 14-folds increase in dissolution rate when compared with pure SM powder. FTIR-ATR and DSC studies confirmed that there was no interaction between the drug and excipients. Further, the LS10 formulation had shown comparable dissolution profile with commercially available tablet formulation. The LS10 formulation showed no significant changes in the physicochemical properties over 3 months during stability studies. Therefore, the SM loaded LS formulation could be considered as an alternative approach to enhance the solubility and dissolution for commercial formulations. Keywords: Liquisolids compacts, solubility, dissolution, carrier, coating material, stability.