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In the era of liquid biopsy, microRNAs emerge as promising candidates for the early diagnosis and prognosis of cancer, offering valuable insights into the disease's development. Among all the existing analytical approaches, even if traditional approaches such as the nucleic acid amplification ones have the advantages to be highly sensitive, they cannot be used at the point-of-care, while sensors might be poorly sensitive despite their portability. In order to improve the analytical performance of existing electroanalytical systems, we demonstrate how a simple chromatographic paper-based disk might be useful to rationally improve the sensitivity, depending on the number of preconcentration cycles. A paper-based electrochemical platform for miRNA detection has been developed by modifying a paper-based electrode with a methylene blue (MB)-modified single-stranded sequence (ssDNA) complementary to the chosen miRNA, namely miR-224 that is associated with lung cancer. A detection limit of ca. 0.6 nM has been obtained in spiked human serum samples. To further enhance the sensitivity, an external chromatographic wax-patterned paper-based disk has been adopted to preconcentrate the sample, and this has been demonstrated both in standard and in serum solutions. For each solution, three miR-224 levels have been preconcentrated, obtaining a satisfactory lowering detection limit of ca. 50 pM using a simple and sustainable procedure. This approach opens wide possibilities in the field of analytical and bioanalytical chemistry, being useful not only for electrochemistry but also for other architectures of detection and transduction. [ABSTRACT FROM AUTHOR]

Cultural heritage objects present a special set of challenges for chemical analysis. Often micro-sampling or even contacting the object is deemed an unacceptable risk to the object. This study examined if specular reflection FTIR, a non-sampling and non-contact analytical technique, can provide insight into chemical composition of the layered coatings on Frédéric Flachéron's paper negatives (1848–1852) in the Harrison D. Horblit Collection of Early Photography, in Houghton Library, at Harvard University. Specular reflection FTIR data confirmed the identification of beeswax and sandarac as the transparentizing media on Flachéron's paper negatives, as previously published by Lee Ann Daffner. However, specular reflection FTIR analysis also indicated that some negatives had additional localized coatings of orange shellac in specific areas of the images. To understand why Flachéron retouched his negatives with orange shellac, modern experimental replications of the paper negative process were performed. Through modern experimentation with the paper negative technique, it was found that Flachéron's coatings of shellac served as an integral part of his image-altering technique. The color of the orange shellac subtly alters contrast and density, but it does not mask an area the way an opaque watercolor or highly pigmented paint might. The fine adjustments to the negatives with orange shellac were an attempt to perfect the contrast in the print, and better render depth and detail. These discoveries add to a growing body of recent research that points to the historic and art historic importance of negatives and coatings in photography. The specificity with which specular reflection FTIR was able to nondestructively identify the chemical composition of the local coating, and specifically target the analysis on the areas in which it appeared, allowed for an understanding of Flachéron's use of local coatings as a retouching method rather than a protective coating. [ABSTRACT FROM AUTHOR]

In the present work, a freshness indicator was developed by immobilizing extracted betacyanins from prickly pear fruit (PFB) onto cellulose filter paper to visually determine fish spoilage. Various properties of the prepared indicator, including color stability, moisture uptake, sensivity to hydrogen sulfide (H 2 S) gas and pH changes, and chemical analysis were studied. The PFB-based indicator exhibited good color stability at various temperatures and times, with no significan color changes observed during storage at 25, 4, and −18 °C for 8 days. The moisture absorption of the indicator based on PFB was lower than that of cellulose paper, which is crucial for colorimetric indicators. Basic nitrogen and sulfur compounds are the main volatile compounds produced during fish spoilage. The results of the present study showed that both total volatile basic nitrogen (TVB-N) and H 2 S gas produced during fish spoilage contributed to the color changes of betacyanin-based colorimetric indicators. The prepared freshness indicators were pH-sensitive, with significant color changes due to TVB-N and H 2 S production during fish storage. A significant correlation was observed between fish quality (pH, TVB-N and total viable count) and the visible color changes of the indicators. The color of the designed indicator shifted from dark pink to pale pink/white during fish storage. These prepared freshness indicators were inexpensive, easy to use, and non-toxic, making them suitable for assessing the quality and shelf life of fish fillets. • A freshness indicator was prepared based on prickly pear fruit betacyanins using cellulose paper. • The prepared indicator was sensitive to not only TVB-N but also H 2 S compounds. • A significant correlation was observed between fish quality and visible color changes. • The prepared indicator is low-cost and efficient for spoilage detection of protein-rich foods. [ABSTRACT FROM AUTHOR]

The general objective of Analytical Chemistry, nowadays, is to obtain best-quality information in the shortest time to contribute to the resolution of real problems. In this regard, electrochemical biosensors are interesting alternatives to conventional methods thanks to their great characteristics, both those intrinsically analytical (precision, sensitivity, selectivity, etc.) and those more related to productivity (simplicity, low costs, and fast response, among others). For many years, the scientific community has made continuous progress in improving glucose biosensors, being this analyte the most important in the biosensor market, due to the large amount of people who suffer from diabetes mellitus. The sensitivity of the electrochemical techniques combined with the selectivity of the enzymatic methodologies have positioned electrochemical enzymatic sensors as the first option. This review, focusing on the electrochemical determination of glucose using paper-based analytical devices, shows recent approaches in the use of paper as a substrate for low-cost biosensing. General considerations on the principles of enzymatic detection and the design of paper-based analytical devices are given. Finally, the use of paper in enzymatic electrochemical biosensors for glucose detection, including analytical characteristics of the methodologies reported in relevant articles over the last years, is also covered. [ABSTRACT FROM AUTHOR]

This document is an exclusive review of catalytic materials and their applications in various fields. It includes reviews on topics such as enzyme-nanoparticle immobilization for biocatalysis, the catalytic activity of gold enzymes, nickel single-atom catalysts for hydrogenation and dehydrogenation reactions, heterogeneous catalysts for oxime hydrogenation, advanced oxidation processes for water and air purification, and selective catalytic reduction technology for reducing NOx emissions from diesel engines. The reviews provide insights into the synthesis, structure, and application of different catalytic materials, highlighting their potential in solving technological challenges in sensing, catalysis, and biomedicine. [Extracted from the article]

The existence of pesticide residues in the hydrosphere, biosphere, and anthroposphere can cause acute or chronic diseases and deteriorate the environment. Therefore, efficient detection of pesticide residues is of great significance to prevent food poisoning, control food pollution, and protect human lives by recognizing their distribution and concentration. Herein, a novel smartphone-coupled three-layered paper-based microfluidic chip is proposed as a facile platform to detect the pesticides. The stereoscopic capillary-driven fluid transport is enabled by the three-layered microfluidic chip configuration. The detection mechanism is based on the enzyme inhibition reaction and the chromatic reaction. The detection results are obtained by a smartphone and figured out by colorimetric quantitative analysis. Taking advantages of the above merits, we demonstrate the utilization of this smartphone-coupled three-layered paper-based microfluidic chip for the effective analysis of typical pesticides (profenofo and methomyl). The linear ranges of profenofo and methomyl are 0.27–2.1 μmol L−1 and 0.14–1.85 μmol L−1, respectively. The corresponding limits of detection in the chips are 55 nM and 34 nM, respectively. The paper-based chips are also highly cost-effective with a total cost of 0.082 ¥ per piece. It can be anticipated that this technique will open new avenues for the mass fabrication of paper-based microfluidic chips and provide state-of-the-art methods in the field of analytical chemistry. [ABSTRACT FROM AUTHOR]

Korean hand papermaking is a renowned cultural tradition in the Korean peninsula. It is still practiced while scientific analysis of paper itself from a large data set is rare. In this study, a set of more than three hundred Korean handmade papers, collected in a reference collection book Hanji: Korean handmade paper, were chemically investigated, and their property data such as colour, pH, grammage, thickness, tensile strength, folding endurance were statistically analysed in order to determine general features for Korean papers. The influence of different paper sheet formation methods (Heullimtteugi vs Gadumtteugi) were revealed by multivariate data analysis and the chemical profiles of raw materials were studied by pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS). The Korean handmade paper samples display colour gamut in the colour space L* (69.9–95.9), a* [(−3)-3], b* (0–20), most have neutral/alkaline pH values. Paper density, fiber orientation and physical properties are influenced by the sheet formation techniques. For instance, Gadumtteugi tends to produce papers with strong fiber orientation while Heullimtteugi produces papers with more evenly distribution of fibers. In addition, Py-GC/MS analysis results show that paper mulberry fibers contain less intensity lignin monomers and more terpenic compounds in comparison with gampi and mitsumata fibers. This study provides paper analysis from large sample set, statistics reveal that the material preparing and making craft determined the paper structure which reflected in their physical properties. These properties influenced paper performance and applications in art creations as well as relics conservation and restoration. The characterized paper sample database could be used for handmade paper studies in East Asian region. Consequently, this study contributes to a better understanding of contemporary Hanji properties as well as improves knowledge on handmade papers from the Korean peninsula. [ABSTRACT FROM AUTHOR]

Tobacco smoke contains a large number of harmful substances and has been widely proved to be able to induce a variety of human diseases. Human eyes are exposed to ambient air for a long time in daily life and are susceptible to air pollutants such as tobacco smoke in the air. Therefore, direct monitoring of characteristic components of tobacco smoke in human tears is expected to efficiently assess the exposure level of tobacco smoke to human eyes. Due to human tears at the microliter level, conventional sample collection and chemical analysis methods are a challenging task. Mass spectrometry (MS) has the unique advantages of high sensitivity, specificity and speed, especially, the development of ambient MS with solid substrates has greatly facilitated direct sample analysis with little or no sample pretreatment. Schirmer paper strip is clinically used for sampling of human tears, which is safe, non-invasive, and can be used for measuring the volume of tears. In this study, a small Schirmer paper strip was further prepared for noninvasive microsampling of human tears which exposed to tobacco smoke, and high voltage and an organic solvent were applied onto Schirmer paper to directly generate paper spray ionization for ambient MS analysis. The good analytical performances, including sensitivity (LOD: 0.1 μg/L, S/N≥3; LOQ: 1.0 μg/L, S/N≥10), precision (RSD: 4.89%-7.61%, n=5, with internal standard), recovery (98%-102.1%, n=5), and linear range (0.5-50 μg/L, R2=0.991 8) were achieved. Monitoring nicotine in human tears under different exposure times was also investigated, showing that the concentration of nicotine will the increase with increasing the exposure time ranging from 0 to 8 min. The nicotine can research to be 45 μg/L after burning a cigarette (about 8 min). The retention time of nicotine in human tears was found to be about 20 min (less than 5%), and the half-life time is about 4 min. Overall, our results show that Schirmer paper spray mass spectrometry could be used for qualitative and quantitative detection of trace environmental exposures such as nicotine in human eyes with many advantages, including safe, noninvasive, easy-to-operation, low-consumption as low as 1.0 μL, and thus has potential for many applications in environmental exposure and human health. [ABSTRACT FROM AUTHOR]

Different heating processes were applied to pretreat the pulp and paper mill sludge to enhance the hydrolysis stage. Hot air oven, autoclave, microwave and water bath were used for comparison. Chemical analyses exposed that all the pretreatment methods have shown improvement in solubilisation of organic matter. Among the pretreatments studied, heat transfer through hot air (80 °C for 90 min) mode had the highest impact on sludge solubilisation. There was an increase in cellulose (P = 0.0096), acid soluble (P = 0.0053) and insoluble lignin (P = 0.0012), but decrease in hemicellulose (P = 0.0009) content after pretreatment. The XRD and FT-IR spectroscopic characterisation shows the development of aliphatic, unsaturated and carbonyl carbon functionalities in the pretreated samples at higher severities. FESEM picture also confirms the change in structure after pretreatment. Thus, pretreatments contribute to disruption of the lignocellulosic structure making the cellulose easily accessible to acidogenic microorganisms. [ABSTRACT FROM AUTHOR]

In this research work, a coated paper was prepared with poly (butylene adipate-co-terephthalate) (PBAT) film to explore its use in eco-friendly food packaging. The paper was coated with PBAT film for packaging using hot pressing, a production method currently employed in the packaging industry. The coated papers were evaluated for their structural, mechanical, thermal, and barrier properties. The structural morphology and chemical analysis of the coated paper confirmed the consistent formation of PBAT bi-layered on paper surfaces. Surface coating with PBAT film increased the water resistance of the paper samples, as demonstrated by tests of barrier characteristics, including the water vapor transmission rate (WVTR), oxygen transmission rate (OTR), and water contact angle (WCA) of water drops. The transmission rate of the clean paper was 2010.40 cc m−2 per 24 h for OTR and 110.24 g m−2 per 24 h for WVTR. If the PBAT-film was coated, the value decreased to 91.79 g m−2 per 24 h and 992.86 cc m−2 per 24 h. The hydrophobic nature of PBAT, confirmed by WCA measurements, contributed to the enhanced water resistance of PBAT-coated paper. This result presents an improved PBAT-coated paper material, eliminating the need for adhesives and allowing for the fabrication of bi-layered packaging. [ABSTRACT FROM AUTHOR]

A rapid method for analyzing lignin in paper using IR reflectance spectra from its surface was developed. IR absorption and reflectance spectra of model paper samples prepared from cellulose fibers obtained from deciduous and coniferous woods with various lignin contents were analyzed. The intensity of the lignin absorption band at 1510 cm after Kubelka-Munk transformation of the paper reflectance spectra and chemical data on the fiber lignin content were well correlated. The analytical relationship between the lignin content in the paper fibers and the intensity of the lignin absorption band was used to estimate the lignin concentration in samples of Russian stamping paper from the 19th century using their IR reflectance spectra. The cellulose structure parameter estimated from the paper reflectance spectra showed that sheets containing lignin (5-16%) consisted entirely of wood fibers and were supplemented with kaolin. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • An integrated paper-based platform is proposed for the HSA concentration detection. • BCG reagent and HSA concentration is induced albumin-BCG complex for RGB detection. • HAS concentration of 36 real-world human samples are measured. • The results are in excellent agreement of R2 = 0.9912 versus official method. Abstract A rapid analytical platform composed of a paper-based chip (µPB-Chip) and a small analytic box is developed to determine the concentration of human serum albumin (HSA). In this study, a Bromocresol Green (BCG) reagent is dropped into the reaction area of the µPB-Chip, and the HSA concentration was derived from the R (red) value intensity of the albumin-BCG complex formed after a reaction process at 37 °C for 12 min. The effectiveness of the developed method is displayed using albumin concentrations ranging from 0 to 5 g/dL in HSA control samples. The measurement results acquired from 36 volunteer patient’s HSA samples are presented to be in good consistency with those obtained utilizing a conventional assay technique (R2 = 0.9912). Ultimately, the results show that the developed platform provides a convenient, economical and dependable method for HSA concentration detection. [ABSTRACT FROM AUTHOR]

On-site rapid monitoring of nitrite as an assessment indicator of the environment, food, and physiological systems has drawn extensive attention. Here, electrokinetic stacking (ES) was combined with colorimetric reaction on a paper-based device (PAD) to achieve colorless nitrite detection with smartphone. In this paper, nitrite was stacked on the paper fluidic channel as a narrow band by electrokinetic stacking. Then, Griess reagent was introduced to visualize the stacking band. Under optimal conditions, the sensitivity of nitrite was 160-fold increased within 5 min. A linear response in the range of 0.075 to 1.0 μg mL−1 (R2 = 0.99) and a limit of detection (LOD) of 73 ng mL−1 (0.86 μM) were obtained. The LOD was 10 times lower than the reported PAD, and close to that achieved by a desktop spectrophotometer. The applicability was demonstrated by nitrite detection from saliva and water with good selectivity, adding 100 times more concentrated co-ions. High recovery (91.0~108.7%) and reasonable intra-day and inter-day reproducibility (RSD < 9%) were obtained. This work shows that the sensitivity of colorless analyte detection-based colorimetric reaction can be effectively enhanced by integration of ES on a PAD.Schematic of the experimental setups (left) and the corresponding images (right) of the actual portable device. [ABSTRACT FROM AUTHOR]

A novel washing technique for microfluidic paper-based analytical devices (μPADs) that is based on the spontaneous capillary action of paper and eliminates unbound antigen and antibody in a sandwich immunoassay is reported. Liquids can flow through a porous medium (such as paper) in the absence of external pressure as a result of capillary action. Uniform results were achieved when washing a paper substrate in a PDMS holder which was integrated with a cartridge absorber acting as a porous medium. Our study demonstrated that applying this washing technique would allow μPADs to become the least expensive microfluidic device platform with high reproducibility and sensitivity. In a model μPAD assay that utilized this novel washing technique, C-reactive protein (CRP) was detected with a limit of detection (LOD) of 5 μg mL. [ABSTRACT FROM AUTHOR]

Smoothness is an important factor in consumer perception of tissue quality, with physical modification and chemical additions to the paper able to enhance tissue handle. Therefore objective measurement of the papers mechanical properties in developing new products and maintaining existing quality is vital. In this study the surface chemical composition of the softener treated paper is investigated using ToF-SIMS, and related to the surface frictional properties of the paper. [ABSTRACT FROM AUTHOR]

Background: Identification of the source of mosquito blood meals is an important component for disease control and surveillance. Recently, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) profiling has emerged as an effective tool for mosquito blood meal identification, using the abdomens of freshly engorged mosquitoes. In the field, mosquito abdomens are crushed on Whatman filter papers to determine the host feeding patterns by identifying the origin of their blood meals. The aim of this study was to test whether crushing engorged mosquito abdomens on Whatman filter papers was compatible with MALDI-TOF MS for mosquito blood meal identification. Both laboratory reared and field collected mosquitoes were tested. Material and methods: Sixty Anopheles gambiae Giles were experimentally engorged on the blood of six distinct vertebrate hosts (human, sheep, rabbit, dog, chicken and rat). The engorged mosquito abdomens were crushed on Whatman filter papers for MALDI-TOF MS analysis. 150 Whatman filter papers, with mosquitoes engorged on cow and goat blood, were preserved. A total of 77 engorged mosquito abdomens collected in the Comoros Islands and crushed on Whatman filter papers were tested with MALDI-TOF MS. Results: The MS profiles generated from mosquito engorged abdomens crushed on Whatman filter papers exhibited high reproducibility according to the original host blood. The blood meal host was correctly identified from mosquito abdomens crushed on Whatman filter papers by MALDI-TOF MS. The MS spectra obtained after storage were stable regardless of the room temperature and whether or not they were frozen. The MS profiles were reproducible for up to three months. For the Comoros samples, 70/77 quality MS spectra were obtained and matched with human blood spectra. This was confirmed by molecular tools. Conclusion: The results demonstrated that MALDI-TOF MS could identify mosquito blood meals from Whatman filter papers collected in the field during entomological surveys. The application of MALDI-TOF MS has proved to be rapid and successful, making it a new and efficient tool for mosquito-borne disease surveillance. [ABSTRACT FROM AUTHOR]

A test procedure is proposed for determining total metals (Cd, Co, Cu, Fe, Hg, Ni, and Zn) using irregular 1-(2-carboxyphenyl)-5-(4-methyl-6-methoxypyrimidine-2-yl)formazan-6-cellulose as an indicator paper. Regions of unreliable color reactions were determined for each of the metals and total metals present in equal concentrations. Statistical processing showed that the Weibull distribution function best describes the experimental results in the unreliable reaction regions. Unreliable reaction was observed in the range (3.6–4.4) × 10–3 mg/L for the test procedure with preconcentration and in the range 1.7–3.4 mg/L for the procedure without preconcentration; the detection limits are 4.4 × 10–3 and 3.4 mg/L, respectively. A synergetic effect of the component mixture was observed in determining total metals. The visual, reflectometric, and atomic absorption determination of total Co, Cu, Fe, Ni, and Zn in natural and tap water was studied; it was shown that the results of test determination agree well with the data of other methods. [ABSTRACT FROM AUTHOR]

Paper spray (PS) is an ambient ionization technique applicable to ionizing analytes from untreated dried biofluid samples. In-field sample analysis could benefit from the capability to use a finger prick of blood to measure drugs in whole blood at low cost and in a short time. Some studies may require specialized blood collection devices that can be used in remote areas. In this study, four different dried blood spot (DBS) devices are used with PS sources and tested for rapid quantification of imatinib and N-desmethyl-imatinib. A triple quadrupole mass spectrometer allows analyte detection with high sensitivity. Analytical figures of merit for the four devices are compared, and it is concluded that several of the novel devices successfully deploy DBS with PS and yield similar results to traditional manual PS methods. Clinical samples collected in a remote location were analyzed as a proof of concept for in-field blood collection and subsequent rapid laboratory analysis. [ABSTRACT FROM AUTHOR]

Tuning the sensing properties of spiropyrans (SPs), which are one of the photochromic molecules useful for colorimetric sensing, is important for efficient analysis, but their synthetic modification is not always simple. Herein, we introduce an alkyne-functionalized SP, the modification of which would be easily achieved via Cu-catalyzed azide-alkyne cycloaddition ("click reaction"). The alkyne-SP was conjugated with a bis(triethylene glycol)-benzyl group (EG-BtSP) or a simple benzyl group (BtSP), forming a triazole linkage from the click reaction. The effects of auxiliary groups to SP were tested on metal-ion sensing and cyanide detection. We found that EG-BtSP was more Ca2+-sensitive than BtSP in acetonitrile, which were thoroughly examined by a continuous variation method (Job plot) and UV-VIS titrations, followed by non-linear regression analysis. Although both SPs showed similar, selective responses to cyanide in a water/acetonitrile co-solvent, only EG-BtSP showed a dramatic color change when fabricated on paper, highlighting the important contributions of the auxiliary groups. [ABSTRACT FROM AUTHOR]

Abstract: Evolutionary behavior of syngas chemical composition and yield have been examined for paper and cardboard at three different temperatures of 800, 900 and 1000°C using CO2 as the gasifying agent at constant flow rate. Specifically the evolution of syngas chemical composition with time has been investigated. Pyrolysis of the sample was dominant at the beginning of the gasification process as observed from the high initial devolatilization of the sample followed by char gasification of material to form syngas for a long period of time. Results provided the role of gasification temperature on kinetics of the CO2 gasification process. Increase in gasification temperature provided increased conversion of the sample material to syngas. Thus the sample conversion to syngas was low at the low temperature of 800°C while at elevated temperatures of 900 and 1000°C substantial enhancement of the kinetics process occurred. The evolution of extensive reaction rate of carbon-monoxide was calculated. Results show that increase in temperature increased the extensive reaction rate of carbon-monoxide. The global behavior of syngas chemical composition examined at three different temperatures revealed a peak in concentration of H2 to exhibit after few minutes into the gasification that changed with gasification temperature. At 800°C gasification temperature peak in H2 was displayed at 3min into gasification while it decreased to only 2min, approximately, at gasification temperatures of 900 and 1000°C. The effect of reactor temperature on CO mole fraction has also been examined. Increase in the gasification temperature enhances the mole fraction of CO yields. This is attributed to the increase in forward reaction rate of the Boudouard reaction (). The results show important role of CO2 gas for the gasification of wastes and low grade fuels to clean syngas. [Copyright &y& Elsevier]

A disposable electrochemical lateral flow paper-based sensing device for heavy metal detection is proposed. The quantification of lead and cadmium in aqueous samples is demonstrated in a range from 10 to 100 ppb with a limit of detection of 7 and 11 ppb respectively. Moreover, the platform itself, which is made of paper, served as a sample pretreatment material due to its filtering properties. Real samples, especially in which the matrix is usually turbid and would in principle need a previous filtration, are successfully analyzed. This lab-on-paper device is simple, low cost, easy to fabricate, and portable, being a promising tool for new point-of-care applications in environmental monitoring, public health, and food safety. [ABSTRACT FROM AUTHOR]

This study presents the research on the chemical analysis and genotoxicity of 28 virgin/recycled paper products in food-contact use. In the chemical analysis, paper products were extracted by reflux with ethanol, and analyzed by gas chromatography/mass spectrometry. 4,4′-bis(dimethylamino)benzophenone (Michler''s ketone: MK), 4,4′-bis(diethylamino)benzophenone (DEAB), 4-(dimethylamino)benzophenone (DMAB) and bisphenol A (BPA) were found characteristically in recycled products. Seventy-five percent of the recycled paper products contained MK (1.7–12 μg/g), 67% contained DEAB (0.64–10 μ g/g), 33% contained DMAB (0.68–0.9 μg/g) and 67% contained BPA (0.19–26 μg/g). Although, BPA was also detected in virgin paper products, the detection levels in the recycled products were ten or more times higher than those in the virgin products. The genotoxicity of paper and paperboard extracts and compounds found in them were investigated by Rec-assay and comet assay. Of the 28 products tested by Rec-assay using Bacillus subtilis, 13 possessed DNA-damaging activity. More recycled than virgin products (75% against 25%) exhibited such activity, which, of the compounds, was observed in BPA, 1,2-benzisothiazoline-3-one (BIT), 2-(thiocyanomethylthio)benzothiazole, 2,4,5,6-tetrachloro-isophthalonitrile, 2,4,6-trichlorophenol (TCP), and pentachlorophenol. The critical toxicant in one virgin paper product was concluded to be BIT. Eight samples with DNA-damaging activity were also tested by comet assay using HL-60 cells; six induced comet cells significantly (five times or higher than the control) without a decrease of viable cells. TCP, BZ, DEAB, and BIT also caused a slight increase in comet cells. In conclusion, we showed that most recycled paper products contain chemicals such as MK, DEAB, DMAB, and BPA, and possess genotoxicity. However, the levels of the chemicals in the recycled products could not explain their genotoxic effects. [Copyright &y& Elsevier]

The applications of various clay minerals are related to their structural, physical, and chemical characteristics. These properties of the clay minerals dictate their utilization in the industries and beneficiation required before usage. The study aimed at establishing the potentiality of acid‐activated clay mineral from Hadar, Afar, Ethiopia. XRD, SEM, energy‐dispersive X‐ray fluorescence (EDXRF), and FT‐IR spectroscopies were employed to characterize the chemical compositions and interaction in the bentonite samples. The XRD results revealed that the native and activated bentonite clay contains similar minerals, such as montmorillonite (MMT) ([Ca, Na]0.33 [Al, Mg]2[Si4O10][OH]2.nH2O), quartz (SiO2), albite (NaAl2SiO6), zeolite (CaAl2O3.SiO2.nH2O), and aluminum silicate. Thus, attributes of the bentonite clay was composed of SiO2 and Al2O3 indicating that it is an aluminosilicate mineral, and the morphology of bentonite was supported by SEM. The chemical analysis by EDXRF revealed that the native bentonite (NB) consisting of 58.18 wt% (SiO2), 14.28 wt% (Al2O3), and Na2O > CaO are the major constituents of the clay with other oxides present in low amount. There was an increase in the SiO2 content in activated bentonites, and the Al2O3, Fe2O3, and MgO contents have decreased by 48.56%, 66.36%, and 84.42%, respectively. The FT‐IR spectra bands at 1627 cm−1 and 1027 cm−1 were attributed to Al–Mg–OH, Al–Al–OH, and Al–OH–O–Si stretching vibration, and the reduction of the content of the octahedral cations is accompanied by a decrease of both OH bending vibrations at 1627 and 3401 cm−1. The FT‐IR result is in clear agreement with the SEM, XRD, and EDXRF studies which indicate sequential degradation of the clay sheet upon acid treatment. Hence, rendering the activated bentonite clay of Hadar has accounted for their demand for different industrial applications such as its use as detoxifier, sealant, binder, fillers for paper, pharmaceutical products, absorbent, adsorbent, catalyst, and nanoclays. [ABSTRACT FROM AUTHOR]

The immense popularity of coffee around the world generates significant amounts of coffee grounds. They are often improperly disposed of, which can have a negative impact on the environment. Due to their chemical composition and physical properties, coffee grounds are an excellent bioenergy material. This paper presents a study of the feasibility of using spent coffee grounds (CG) as an additive to pine sawdust (PS) pellets to improve their energy properties. The tests were carried out on samples of pellets consisting of 100% PS, 100% CG, and mixtures of 95% PS and 5% CG, 85% PS and 15% CG, and 70% PS and 30% CG. Physical and chemical analyses were carried out to determine the suitability of the obtained pellet as a biofuel in accordance with ISO 17225. Combustion tests were also carried out in a laboratory boiler to analyze flue gases and determine CO and NOx emissions in accordance with EN-303-5 for biomass boilers. The amount of emitted volatile organic compounds (VOCs) was also determined. Experimental results show that the addition of CG to PS reduces the durability of the pellets and increases CO and NOx emissions but increases their energy value and reduces the amount of VOC emissions. The requirements of both standards were fulfilled with a mixture of 95% PS and 5% CG. However, test results show that it is possible to add CG to PS in amounts up to 15%, although this will require additional research. [ABSTRACT FROM AUTHOR]

Simple Summary: In forensic entomology, insects are used to estimate the time since death and to answer other investigative questions, such as determining if the body was moved postmortem or identifying the season of death. In funerary archeoentomology, insects provide information related to the season of death, body transfer, and funerary practices. To obtain this information, the correct identification of specimens collected from the scene is fundamental. In old cases and archeological contexts, the majority of entomological evidence samples found are fly puparia, barrel-like structures formed from the third-instar larval cuticle where metamorphosis takes place. Despite recent publications of identification keys for certain fly larvae and adults, there is still a lack of tools for puparium identification. This problem is exacerbated by the scarcity of diagnostic features present on the puparia. This paper critically reviews the techniques available for puparium identification in addition to traditional morphological analysis. It describes DNA-based approaches and chemical analyses of cuticular lipids and hydrocarbons, highlighting the importance of using non-invasive methods to guarantee the repeatability of the analysis—a key element in forensic science—or to preserve precious and unique specimens from museum collections. Diptera identification is fundamental in forensic entomology as well as in funerary archeoentomology, where the challenge is exacerbated by the presence of immature stages such as larvae and puparia. In these two developmental stages, specimens possess a very limited number of diagnostic features, and for puparia, there is also a lack of identification tools such as descriptions and identification keys. Morphological analysis, DNA-based techniques, and cuticular chemical analyses all show good potential for species identification; however, they also have some limitations. DNA-based identification is primarily hindered by the incompleteness of genetic databases and the presence of PCR inhibitors often co-extracted from the puparial cuticle. Chemical analysis of the cuticle is showing promising results, but this approach is also limited by the insufficient profile database and requires specific, expensive equipment, as well as trained personnel. Additionally, to ensure the repeatability of the analysis—a critical aspect in forensic investigations—and to preserve precious and unique specimens from museum collections, non-invasive protocols and techniques must be prioritized for species identification. [ABSTRACT FROM AUTHOR]

Paper-based devices serve to address many analytical questions both inside and outside of the laboratory setting. For the first time, yeast is used to construct a whole-cell, paper-based biosensor device. This biologically based paper analytical device (BioPAD) is sensitive to antibiotics in the tetracycline family, and it could potentially address questions of pharmaceutical quality as well as antibiotic contamination in liquids. Our BioPAD can qualitatively discriminate the presence/absence of doxycycline over a range of 30-10,000 μg/mL. In an analysis of a doxycycline dosage form (tablet) commonly used for malaria prophylaxis, BioPADs identified the presence of antibiotic with 92 and 95 % sensitivity, evaluated by eye and computer-assisted image analysis, respectively, with no false positives by either method. BioPADs were found to remain viable for at least 415 days when stored at 4 °C. This research demonstrates the utility of whole yeast cells in paper-based pharmaceutical testing, and it highlights the potential for the development of yeast-based BioPADs to address a range of qualitative analytical questions, especially in low resource settings. [ABSTRACT FROM AUTHOR]

Use of non-degradable plastics in food packaging is alarming for the environment as they are often thrown away after short consumption. Though papers are replacing plastics in different sectors, their low water resistance limits their use in food packaging. in the past, water-resistant papers have been fabricated, but the natural degradability of the paper has been compensated. This study proposes water-resistant yet biodegradable papers from naturally abundant wastes, such as banana plant (BP) and water hyacinth (WH) and validates their properties for practical packaging uses. The resources were completely used, avoiding generation of any in-process biomass residue. This study for the first time reports the impact of ethyl cellulose (EC) coating (∼10 μm) on paper surfaces. The morphology and chemical analysis of the coated papers confirmed the consistent formation of EC layer on paper surfaces. The presence of EC significantly reduced the vapour transmission (22–30%) and moisture content (6–11%) of the papers. Water drops were stable on the coated surfaces at least for 20 min and then were wiped off leaving a dry surface. EC coating considerably increased the tensile index, i.e., 13–17% for BP and 20–35% for WH, though elongation and modulus properties remained almost unchanged. All the papers showed ultraviolet (UV)-resistance, while the coated papers were more transparent in the visible light region. Overall results confirmed the potential of the proposed EC-coated papers as a promising alternative to single-use plastics in food packaging. [Display omitted] • Water-resistant yet bio-friendly paper was made by ethyl cellulose (EC) coating. • Banana plant and water hyacinth were utilised as low-cost source of paper making. • Water drops were resisted by coated surface for at least 20 min. • Tensile index and transparency improved by coating though vapour transport reduced. [ABSTRACT FROM AUTHOR]

Abstract: This work reviews the different analytical methods that have been proposed in the field of forensic dating of inks from different modern writing instruments. The reported works have been classified according to the writing instrument studied and the ink component analyzed in relation to aging. The study, done chronologically, shows the advances experienced in the ink dating field in the last decades. [Copyright &y& Elsevier]

A new method for improved development of latent fingermarks on thermal paper by 1,8-diazafluoren-9- one (DFO) treatment is described. Compared with conventional DFO solution, the mixed solution of DFO/ PVP (polyvinylpyrrolidone) described here reduces black background staining without removing the thermosensitive layer and develops fingermarks by the reaction of DFO with amino acid deposited on the thermal paper's surface. An advantage of this approach is that the developed fluorescent fingermarks have high contrast and can be observed and photographed when excited in the 515 nm region and observed through an orangered barrier long-pass filter with no background coloration. In addition, the method reported here does not involve any pre- or post treatment of the substrate and exhibits high sensitivity with good stability. Experimental results showed that the method was able to develop very old fingermarks, up to 154 days old, demonstrating the feasibility of using the method to develop identifiable latent fingermarks operationally. Furthermore, we extended our experiments to various types of thermal papers. Notably, this method exhibits several very attractive features, namely time saving, simple procedures, inexpensive, convenient operation, and PVP is non-toxic and reasonably priced. Finally, in this study an attempt has been made to explain the reaction mechanism of the process and the effects of PVP. [ABSTRACT FROM AUTHOR]

A simple protocol for rapid quantitation of acylcarnitines in serum and whole blood has been developed using paper spray mass spectrometry. Dried serum and whole blood containing a mixture of ten acylcarnitines at various concentrations were analyzed as spots from paper directly without any sample pretreatment, separation, or derivatization. The composition of the spray solvent was found to be a critical factor: for serum samples, spray solvent of methanol/water/formic acid (80:20:0.1) gave the best signal intensity while for blood samples which contain more matrix components, acetonitrile/water (90:10) was a much more suitable spray solvent. For the paper type and size used, 0.5 μL of sample provided an optimal signal for both serum and whole blood samples. For quantitative profiling, the limits of quantitation obtained from both serum and blood were much lower than the clinically validated cutoff values for diagnosis of fatty acid oxidation disorders in newborn screening. Linearity ( R > 0.95) and reproducibility (RSD ∼10 %) were achieved in the concentration ranges from 100 nM to 5 μM for the C2 acylcarnitine, and for other acylcarnitines, these values were from 10 to 500 nM. Acylcarnitine profiles offer an effective demonstration of the fact that paper spray mass spectrometry is an appropriate, simple, rapid method with high sensitivity and high reproducibility applicable to newborn screening tests. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

This study presents research into the unique method of depositing carbon layers onto processed surfaces, during finishing with abrasive films, on a global basis. The authors of this article are holders of the patent for this method. What makes this technology outstanding is that it integrates processes, whereby micro-finishing and the deposition of a carbon layer onto freshly exposed surface fragments is achieved simultaneously, in a single process. Among the main advantages accruable from this process is the reduction of surface irregularities, while the deposition of a carbon layer is achieved simultaneously. Ultrathin graphite layers can be widely used in conditions where other methods of reducing the coefficient of friction are not possible, such as in regard to micromechanisms. This article illustrates the application of carbon coating, end on, on a surface processed with abrasive film, containing intergranular spaces, saturated with graphite. Thin carbon layers were obtained on two substrates that did not contain carbon in their initial composition: soda–lime glass and a tin–bronze alloy. It was performed through microscopic examinations of the produced surface, roughness analyses of these surfaces, and analysis of the chemical compositions determined by two methods, namely EDS and GDOES, proving the existence of the coatings. The aim of this paper is to prove the possibility and efficiency of using graphite-impregnated lapping films in the deposition process of carbon films, with improved surface smoothness, durability, and wear resistance. The produced coatings will be tested in regard to their operational properties in further research. The authors underline the potential of this method to revolutionize surface treatment processes, due to the significant advantages it offers across various industries. [ABSTRACT FROM AUTHOR]

The dispersive liquid-liquid microextraction (DLLME) is one of the most popular miniaturized extraction procedures. In this paper, the degree of dispersion and dispersion stability were studied with the aim to assess the correlations of these parameters with efficiency for the selected analytical application. The dependence between the degree of dispersion (cloudy state quality) and its stability obtained by various emulsification procedures, such as solvent-assisted emulsification (using various dispersive solvents) and mechanical emulsification (using auxiliary energies), is investigated and discussed. It was found out that the degree of dispersion depends on the type of emulsification procedure and decreases in the series: solvent-assisted (SA-) = ultrasound-assisted (UA-) > air-assisted (AA-) > vortex-assisted (VA-) emulsification. The emulsion stability depends on the degree of dispersion and there were 1810 and 2070 s for the most effective emulsification procedures, such us solvent-assisted and ultrasound-assisted emulsification, respectively. A comparison between the sensitivity of the analytical methods (using spectrophotometric determination of the anionic surfactants) and the degree of dispersion have been made. The sensitivity of the methods was ranked as follows: DLLME > UA-LLME > VA-LLME > AA-LLME. [ABSTRACT FROM AUTHOR]

Three decades after A. P. de Silva's seminal paper introduced the concept of logic gates at the molecular level, the field of molecular logic gates (MLGs) has witnessed significant advancements. MLGs are devices designed to perform logical operations, utilizing one or more physical or chemical stimulus signals (inputs) to generate an output response. Notably, MLGs have found diverse applications, with optical detection of analytes emerging as a notable evolution of traditional chemosensors. Organic synthesis methods are pivotal in crafting molecular architectures tailored as optical devices capable of analyte detection through logical functions. This review delves into the fundamental aspects and physical–chemical properties of MLGs, with a particular emphasis on synthetic strategies driving their design. [ABSTRACT FROM AUTHOR]

An important application of CRISPR interference (CRISPRi) technology is for identifying chemical-genetic interactions (CGIs). Discovery of genes that interact with exposure to antibiotics can yield insights to drug targets and mechanisms of action or resistance. The objective is to identify CRISPRi mutants whose relative abundance is suppressed (or enriched) in the presence of a drug when the target protein is depleted, reflecting synergistic behavior. Different sgRNAs for a given target can induce a wide range of protein depletion and differential effects on growth rate. The effect of sgRNA strength can be partially predicted based on sequence features. However, the actual growth phenotype depends on the sensitivity of cells to depletion of the target protein. For essential genes, sgRNA efficiency can be empirically measured by quantifying effects on growth rate. We observe that the most efficient sgRNAs are not always optimal for detecting synergies with drugs. sgRNA efficiency interacts in a non-linear way with drug sensitivity, producing an effect where the concentration-dependence is maximized for sgRNAs of intermediate strength (and less so for sgRNAs that induce too much or too little target depletion). To capture this interaction, we propose a novel statistical method called CRISPRi-DR (for Dose-Response model) that incorporates both sgRNA efficiencies and drug concentrations in a modified dose-response equation. We use CRISPRi-DR to re-analyze data from a recent CGI experiment in Mycobacterium tuberculosis to identify genes that interact with antibiotics. This approach can be generalized to non-CGI datasets, which we show via an CRISPRi dataset for E. coli growth on different carbon sources. The performance is competitive with the best of several related analytical methods. However, for noisier datasets, some of these methods generate far more significant interactions, likely including many false positives, whereas CRISPRi-DR maintains higher precision, which we observed in both empirical and simulated data. Author summary: CRISPRi technology is revolutionizing research in various areas of the life sciences, including microbiology, affording the ability to partially deplete the expression of target proteins in a specific and controlled way. Among the applications of CRISPRi, it can be used to construct large (even genome-wide) libraries of knock-down mutants for profiling antibacterial inhibitors and identifying chemical-genetic interactions (CGIs), which can yield insights on drug targets and mechanisms of action and resistance. The data generated by these experiments (i.e., sgRNA counts from high throughput sequencing) is voluminous and subject to various sources of noise. The goal of statistical analysis of such data is to identify significant CGIs, which are genes whose depletion sensitizes cells to an inhibitor. In this paper, we show how to incorporate both sgRNA efficiency and drug concentration simultaneously in a model (CRISPRi-DR) based on an extension of the classic dose-response (Hill) equation in enzymology. This model has advantages over other analytical methods for CRISPRi, which we show using empirical and simulated data. [ABSTRACT FROM AUTHOR]

Siderophores are a class of small molecules renowned for their high iron binding capacity, essential for all life forms requiring iron. This article provides a detailed review of the diverse classifications, and biosynthetic pathways of siderophores, with a particular emphasis on siderophores synthesized via nonribosomal peptide synthetase (NRPS) and non-NRPS pathways. We further explore the secretion mechanisms of siderophores in microbes and plants, and their role in regulating bioavailable iron levels. Beyond biological functions, the applications of siderophores in medicine, agriculture, and environmental sciences are extensively discussed. These applications include biological pest control, disease treatment, ecological pollution remediation, and heavy metal ion removal. Through a comprehensive analysis of the chemical properties and biological activities of siderophores, this paper demonstrates their wide prospects in scientific research and practical applications, while also highlighting current research gaps and potential future directions. [ABSTRACT FROM AUTHOR]

One of the emerging trends in modern analytical and bioanalytical chemistry involves the substitution of enzyme labels (such as horseradish peroxidase) with nanozymes (nanoparticles possessing enzyme-like catalytic activity). Since enzymes and nanozymes typically operate through different catalytic mechanisms, it is expected that optimal reaction conditions will also differ. The optimization of substrates for nanozymes usually focuses on determining the ideal pH and temperature. However, in some cases, even this step is overlooked, and commercial substrate formulations designed for enzymes are utilized. This paper demonstrates that not only the pH but also the composition of the substrate buffer, including the buffer species and additives, significantly impact the analytical signal generated by nanozymes. The presence of enhancers such as imidazole in commercial substrates diminishes the catalytic activity of nanozymes, which is demonstrated herein through the use of 3,3′-diaminobenzidine (DAB) and Prussian Blue as a model chromogenic substrate and nanozyme. Conversely, a simple modification to the substrate buffer greatly enhances the performance of nanozymes. Specifically, in this paper, it is demonstrated that buffers such as citrate, MES, HEPES, and TRIS, containing 1.5–2 M NaCl or NH4Cl, substantially increase DAB oxidation by Prussian Blue and yield a higher signal compared to commercial DAB formulations. The central message of this paper is that the optimization of substrate composition should be an integral step in the development of nanozyme-based assays. Herein, a step-by-step optimization of the DAB substrate composition for Prussian Blue nanozymes is presented. The optimized substrate outperforms commercial formulations in terms of efficiency. The effectiveness of the optimized DAB substrate is affirmed through its application in several commonly used immunostaining techniques, including tissue staining, Western blotting assays of immunoglobulins, and dot blot assays of antibodies against SARS-CoV-2. [ABSTRACT FROM AUTHOR]

This paper highlights the importance of the collection of data that is of suitable quality and of appropriate frequency and/or spatial intensity for the monitoring of aquatic systems. The advantages of automated techniques, such as flow analysis, in monitoring are emphasized, as is the selection of parameters that address the objectives of monitoring. The potential of nascent microfluidic and paper-based analytical techniques as tools for water quality monitoring is examined. [ABSTRACT FROM AUTHOR]

The possibility of using three groups of azo compounds in chemical tests based on the principles of precipitation paper chromatography is considered. The first group consists of the reagents showing the highest affinity to cellulose (Congo Red, Brilliant Yellow, Stilbazo, Cadion IREA, Sulfarsazen, and Titan Yellow). These reagents are immobilized on paper and are not washed out of it in acidic, alkaline, and neutral solutions. The immobilization of the reagents results in a bathochromic shift of their absorption bands with respect to their solutions and enhances the acidic properties of the reagents. The second group comprises compounds that are immobilized on paper only in acidic solutions (mono- and bisazo derivatives of chromotropic acid: Arsenazo II, Arsenazo III, Orthanilic K, Sulfochlorophenol S, Chlorophosphonazo III, and Carboxyarsenazo). Their immobilization on paper does not lead to a shift in the absorption spectra and acidic properties. The third group consists of compounds that are immobilized on paper either in acidic or in alkaline solutions (Acid Chrome Dark Blue, Eriochrome Black T, Magneson KhS, and Eriochrome Blue Black R). They are absorbed by cellulose as free acids in acidic solutions and as sodium salts in alkaline solutions. Test procedures have been developed for the determination of acids; alkalis (0.1–100 mM); the total alkalinity of water (0.2–35 mM); the total acidity of water (0.2–20 mM); Cd, Al, and Pb (1–200 mg/L); Al, Th, U, and Zr (0.5–200 mg/L); and the total hardness of water (0.05–40 mM). The length of the colored zone in test strips laminated into a polymer film and contacting the test solution through a narrow edge is the analytical signal. The relative standard deviation does not exceed 30%; the analysis time is 10–15 min. [ABSTRACT FROM AUTHOR]

Microfluidic paper-based analytical devices (μPADs) have attracted much attention over the past decade. They embody many advantages, such as abundance, portability, cost-effectiveness, and ease of fabrication, making them superior for clinical diagnostics, environmental monitoring, and food safety assurance. Despite these advantages, μPADs lack the high sensitivity to detect many analytes at trace levels than other commercial analytical instruments such as mass spectrometry. Therefore, a preconcentration step is required to enhance their sensitivity. This review focuses on the techniques used to separate and preconcentrate the analytes onto the μPADs, such as ion concentration polarization, isotachophoresis, and field amplification sample stacking. Other separations and preconcentration techniques, including liquid-solid and liquid-liquid extractions coupled with μPADs, are also reviewed and discussed. In addition, the fabrication methods, advantages, disadvantages, and the performance evaluation of the μPADs concerning their precision and accuracy were highlighted and critically assessed. Finally, the challenges and future perspectives have been discussed. • A critical review of the preconcentration techniques for μPADs is presented. • Both online and offline preconcentration techniques are included. • The approaches for effective separation and preconcentration of chemical and biochemical analytes are highlighted. • A comparison between the preconcentration techniques is discussed. • Challenges and future outlooks of preconcentration techniques for μPADs are presented. [ABSTRACT FROM AUTHOR]

A wet laboratory study of chemical information processing in Brownian (random walk) environments is presented. Point samples of adsorbed dyes were subject to diffusion on paper chromatography sheets; the resulting images were recorded digitally using an office scanner. The experiments enabled the measurement of four types of information along with the attendant costs of work and time. The data are examined for their statistical distribution and scaling properties and Fourier spectral components. Whereas theory, calculations, and reversible pathways were central to the previous paper, the present study is devoted to experiments and irreversible transformations. Overall, the results establish several key points about information of four varieties purchased in real-time Brownian venues. The points concern the kinetics of information, memory effects, and the distributions of information changes with energy. [ABSTRACT FROM AUTHOR]

In a search for mineral oil substitutes, we focus on silicone and ester oil. These insulating oils are fire-resistant and environmentally friendly. In previous studies, we investigated streaming electrification and dielectric breakdown phenomena in these new oils and found that their performance was similar to or better than that of mineral oil. In the present study, we focus on the thermal degradation of insulating oils. Thermal degradation tests in the presence of a solid insulator and copper carried out for 1000 h at 130 and 180 °C. Color changes, chemical analysis and dielectric breakdown characteristics were also investigated during thermal degradation of the insulating oils. We also investigated the mechanical strength of the solid insulator. The characteristics of aged oils were compared with those of fresh oils. Tested silicone oil presents better performance than esters and mechanical characteristics of paper remain unchanged in all resistance liquids. [ABSTRACT FROM AUTHOR]

This research study shows for the first time the hydration reaction of Activated Art Paper Sludge (AAPS)-lime mixtures cured at 20°C. Two mixtures series were prepared using weight ratios of 3:1 and 1:1 for AAPS/lime. The kinetics of the hydration reaction was investigated by characterization techniques such as X-ray diffraction, thermo-gravimetrical and differential thermal analysis, 27Al and 29Si {1H} magic angle spinning nuclear magnetic resonance. Results show higher quantity of hydrated phases formed with the increase of the AAPS/lime ratio (such as calcium silicates hydrates (C–S–H), hydrated tetracalcium monocarboaluminate , and hydrotalcite-like phases), specially C–S–H exhibiting a major incorporation of Al3+ into silicate chains, increasing its medium chain length. It becomes demonstrated that mechanical performance of the studied mixtures will be directly influenced by all these parameters. [ABSTRACT FROM AUTHOR]

Prof. Pingarrón was the mentor of the research group "Electroanalysis and (Bio)Electrochemical Sensors" (GEBE) until November 2020, and Prof. Susana Campuzano took over leadership from then. After an extensive voting period, we are proud to present the Best Paper Award to "Carbon Dots and Graphene Quantum Dots in Electrochemical Biosensing [[1]]" from corresponding authors Dr. Susana Campuzano and Prof. Dr. José M. Pingarrón. During 2008 and 2009, she enjoyed a Juan de la Cierva research contract in the Department of Molecular Microbiology and Infection Biology at the Centro de Investigaciones Biológicas Margarita Salas of the Consejo Superior de Investigaciones Científicas (CIB Margarita Salas-CSIC) in Madrid under the supervision of Prof. Ernesto García. [Extracted from the article]

A sensitive biotest for determining acetylcholinesterase inhibitors has been developed on the basis of a paper matrix and an electric eel ( Electrophorus electricus) tissue preparation with high enzymatic activity. Photometric detection at λ = 480 nm based on the ferricyanide reaction (resulting in the formation of copper ferricyanide) was used. The biotest allows the determination of carbamate inhibitors (eserine and neostigmine) and sanguinarine (an isoquinoline alkaloid) at levels of 10−6 to 10−5 M. [ABSTRACT FROM AUTHOR]

The requirement to establish novel methods for visual detection is attracting attention in many application fields of analytical chemistry, such as, healthcare, environment, agriculture, and food. The research around subjects like "point‐of‐need", "hue recognition", "paper‐based sensor", "fluorescent sensor", etc. has been always aimed at the opportunity to manufacture convenient and fast‐response devices to be used by non‐specialists. It is possible to achieve economic rationality and technical simplicity for optical sensing toward target analytes through introduction of fluorescent semiconductor/carbon quantum dot (QD) and paper‐based substrates. In this Review, the mechanisms of anthropic visual recognition and fluorescent visual assays, characteristics of semiconductor/carbon QDs and ratiometric fluorescence test paper, and strategies of semiconductor/carbon QD‐based hue recognition are described. We cover latest progress in the development and application of point‐of‐need sensors for visual detection, which is based on a semiconductor/carbon quantum dot‐based hue recognition strategy generated by ratiometric fluorescence technology. [ABSTRACT FROM AUTHOR]

The regulation of the pyrolysis process is a key step in increasing the carbon sequestration capacity of biochar. The effect of K3PO4 addition on the yield, chemical composition, characteristic functional groups, macromolecular skeleton, graphite crystallites, and stability of biochar was studied in this paper using two-dimensional infrared correlation spectroscopy (2D-PCIS), X-ray photoelectron spectroscopy, Raman spectrum, and other characterization methods combined with thermal/chemical oxidation analysis. It is discovered that adding K3PO4 may effectively minimize the graphitization temperature range and increase biochar's yield, aromaticity, H/C ratio, and proportion of refractory/recalcitrant organic carbon. The 2D-PCIS and Raman analysis revealed that K3PO4 mostly promoted the dehydrogenation and polycondensation process of the aromatic rings in the char precursor, transforming the amorphous carbon structure of biochar into an ordered turbostratic microcrystalline structure. K3PO4 enhanced biochar stability mostly at medium-high temperatures (350 ~ 750℃) by stimulating the transformation of unstable structures of biochar to stable carbon-containing structures or by inhibiting the interaction of its active sites with oxidants through the mineralization process. A 20% phosphorus addition increased biochar's refractory index (R50) by roughly 11%, and it also boosted biochar's oxidation resistance (H2O2 or K2CrO4) efficiency, reducing carbon oxidation loss by up to 7.31%. However, at higher temperatures (> 750 ℃), the doping of phosphorus atoms into the carbon skeleton degraded the biochar structure's stability. The results of this study suggest that using exogenous phosphorus-containing additives is an efficient way to improve the stability of biochar. Highlights: K3PO4 promoted biochar precursor's dehydrogenation/polycondensation process to form fused-ring aromatic structures. K3PO4 increased recalcitrant carbon proportion and shielded biochar's active sites through the mineralization process. By adding 20 wt% of K3PO4, the thermal and chemical stability of biochar were enhanced by 11% and 7%, respectively [ABSTRACT FROM AUTHOR]

The paper proposes an overview of the primary applications of generalized two-dimensional correlation spectroscopy (2D-COS) to analytical chemistry. 2D-COS is a method used to analyze datasets obtained by spectroscopic measurements. This approach is based on the use of 2D correlation maps to detect and analyze correlations between different spectral regions or data from two measurement methods. The objective of employing 2D-COS is to enhance the volume of analytical information by uncovering latent correlations within the data. Analysis of such correlations for series of spectral data, acquired over a range of analyte concentrations, pH values, or component ratios in mixtures, and also under varying temperatures or other external factors, enables investigating and elucidating chemical processes and interactions. This information is not readily attainable directly from the spectra. In comparison to one-dimensional spectra, 2D-COS excels in the significance of analytical information, particularly in the identification of components and the determination of the composition of complex mixtures. 2D-COS can also be used for monitoring changes in a sample over time, which makes it a valuable tool for studying dynamically evolving systems. Overall, 2D-COS is a sufficiently versatile approach that can be employed in conjunction with numerous methods, addressing a wide range of analytical tasks and complex samples, also without sample preparation. The review highlights achievements in the application of 2D-COS by the beginning of September 2023. [ABSTRACT FROM AUTHOR]

Ordinary differential equations are often employed in chemical kinetics mathematical modeling. The theoretical results for a model of a multi-step chemical kinetic process are presented in this article. This model seeks to describe both the complicated kinetics of complex chemical processes and the steady state behavior of chemical species. Reduction techniques are used to divide fast and slow processes according to their time scales, which simplifies the model. As a result, the quick processes are removed, making the slow processes the main emphasis of a reduced-dimensional model. The paper concentrates on a two-step reversible reaction mechanism for model reduction, which reduces the complexity of the entire reaction process. The phase flow of solution trajectories close to equilibrium points is also given special consideration in the analysis as it offers a clear and pertinent depiction of the behavior of the system. The physical properties of the observed data are further shown via MATLAB simulations. Sensitivity analysis computes parameters, revealing their impact on species behavior, visually presenting the parameter impact. [ABSTRACT FROM AUTHOR]

In metallurgical practice, the material is considered of adequate quality if it meets the customer's expectations. It is necessary to take representative samples and perform quality testing to avoid financial and intangible losses. Sample contamination and matrix and surface quality play a significant role in the accuracy of chemical analyses. The purpose of this paper is to point out the advantages of specific methods of taking samples, such as immersion and spoon sampling of molten metal, and, in the experimental part, to assess the impacts of factors affecting the quality of the sampling. The influence of time of final sampling on determining the true amount of magnesium during a single melt and the influence of duration of mixing of molten cast iron on the accuracy of chemical analysis of the control sample were investigated. It is important that the time between the modification and casting of the liquid cast iron from the casting ladle be as short as possible. This is because the magnesium burns out and thus the chemical analysis of the sample taken is not accurate. Another important factor is ensuring the melt before sampling is homogenized and has the minimum prescribed temperature (1420 °C). Increasing sample collection time will cause changes in its chemical composition. [ABSTRACT FROM AUTHOR]