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This study proposed a proof-of-concept methodology for the investigation of paper samples by utilizing ATR-FTIR spectroscopy supported by chemometric methods. An attempt on the analysis of aged writing papers due to the degradation of their chemical constituents with time has been made. The degradation of its constituents with time is directly linked to the age of the paper since its production. This further links the questioned document with the fraudster, and sometimes it becomes crucial information in the court of law to reach to conclusion. The present study offers a method to discriminate, and estimate the age of unknown writing paper. The statistical models like Curve Estimation (CE), multiple linear regressions (MLR), and partial least squares regression (PLSR), are built to predict the age of the papers. The maximum dating errors are in the CE model whereas, MLR and PLSR models show excellent age estimation of unknown paper with minimum error of ±5 days and ±3 days in actual and estimated date of artificial ageing respectively. The present methodology is expected to provide valuable insight for answering the queries related to the date/age of the suspected document documents/paper artefacts. [ABSTRACT FROM AUTHOR]

The re-profiling from paper-grade to dissolving pulp production is a common trend for acid sulfite cooking of wood. This provides substantial changes in the composition of the spent sulfite liquor (SSL) affecting its potentialities in subsequent processing within the biorefinery concept. In this work, a comparative analysis of the chemical composition of SSL was performed from the magnesium-based acid sulfite cooking of Eucalyptus globulus wood to produce the paper-grade and dissolving pulps. More severe pulping conditions required for dissolving pulp production led to a substantial increase in volatile compounds in SSL, such as acetic acid, methanol, and furfural. At the same time, the amounts of dissolved sugars and lignosulfonates (LS) were increased to a less extent. The main changes detected in LS were related to the increase of its molecular weight, degree of condensation, and sulfonation degree. The increased concentration of the sulfuric acid in SSL was one of the reasons for these changes. [ABSTRACT FROM AUTHOR]

Pyrolysis of medical waste components combined via a novel systematic combination approach (sequentially binary, ternary, and quaternary copyrolysis) was conducted at 400°C to investigate the synergy between medical waste components in improving chemical characteristics and yields of pyrolytic oil. Pyrolysis of hydrocarbon-polymer-containing materials such as medical gloves and rubber bands produced more than 30% of liquid products with substantial compositions of saturated aliphatic hydrocarbon polymers. On the other hand, moisture- and carbonyl-rich pyrolytic liquid products with low selectivity were obtained from pyrolysis of lignocellulosic biomass waste such as HVS paper (houtvrij schrijfpapier, meaning "writing paper made from wood pulp") and garden waste. Binary copyrolysis of lignocellulosic biomass and medical gloves exhibited improvement on pyrolytic liquid yield and selectivity toward saturated aliphatic hydrocarbon polymers due to hydrogen donor as the medical glove fraction became dominant. The addition of rubber band to the mixture of HVS paper and medical face masks enhanced the pyrolytic liquid yield. The pyrolysis of the mixture of HVS paper, medical face masks, medical gloves, and either rubber bands or cotton fabrics with mixture ratio of 60:20:10:10 yielded the most optimum pyrolytic liquid yield with significant distribution of alkanes in the pyrolytic liquid products. [ABSTRACT FROM AUTHOR]

Food-contact materials, including paper, have to comply with a basic set of criteria concerning safety. This means that paper for food contact should not give rise to migration of components, which can endanger human health. The objectives of this pilot study were, first, to compare paper of different qualities as food-contact materials and to perform a preliminary evaluation of their suitability, from a safety point of view, and, second, to evaluate the use of different in vitro toxicity tests for screening of paper and board. Paper produced from three different categories of recycled fibres (B-D) and a raw material produced from virgin fibres (A) were obtained from industry, and extracts were examined by chemical analyses and diverse in vitro toxicity test systems. The products tested were either based on different raw materials or different treatments were applied. Paper category B was made from 40% virgin fibres, 40% unprinted cuttings from newspapers, and 20% de-inked newspapers and magazines. Paper categories C and D were based on newspapers and magazines. However, paper D was de-inked, whereas C was not. To identify constituents of the papers with a potential to migrate into foodstuff, samples of the paper products were extracted with either 99% ethanol or water. Potential migrants in the extracts were identified and semiquantified by GC-IR-MS or GC-HRMS. In parallel to the chemical analyses, a battery of four different in vitro toxicity tests with different endpoints were applied to the same extracts: (1) a cytotoxicity test using normal human skin fibroblasts. The test was based on measurements of the reduction of resazurin to resorufin by cellular redox processes and used as a screening test for acute or general toxicity; (2) a Salmonella/microsome assay (Ames test) as a screening test for mutagenic and potentially carcinogenic compounds; (3) a recombinant yeast cell bioassay as a screening test for compounds with oestrogenic activity; (4) an aryl hydrocarbon (Ah)-receptor assay (CALUX assay) as a screening test for compounds with dioxin-like activity. In addition, the papers were tested for microbial content and, in general, the microbiological load was quite low. The following microorganisms were counted and identified on both surface and homogenized pulp samples: the total number of aerobic bacteria, the number of aerobic and anaerobic spore formers, the number of Bacillus cereus/thuringiensis, and the number of yeast and moulds. The chemical analyses showed a significantly higher amount and different composition pattern of chemicals extracted with ethanol compared with water. Analyses of the ethanol extracts showed a distinctly smaller number and lower concentrations of chemicals in extracts prepared from sample A compared with extracts of samples B–D. The compounds identified in B–D were similar, but the amounts were lower in B compared with C and D. In accordance with the chemical analyses, the water extracts were less cytotoxic than the ethanol extracts. The extract prepared from virgin fibres was less cytotoxic than the extracts prepared from paper made from recycled fibres, and extracts prepared from C was the most cytotoxic. None of the extracts showed mutagenic activity. No conclusion about the oestrogenic activity could be made, because all extracts were cytotoxic to the test organism (yeast cells). Ethanol extracts of A and B showed a negligible positive response in the Ah-receptor assay at the highest nontoxic concentration, whereas C and D showed a more pronounced effect with C being the most potent. A comparable weak effect of water extracts of samples B–D was observed, too. However, the active compound(s) was not identified by chemical analyses. [ABSTRACT FROM AUTHOR]

Questioned documents analysis includes: handwriting comparison, analysis of the ink and the printer used in the production of the documents, and the physical and chemical characterization of the cellulosic substrate (paper) of the documents. In many situations in life, for financial, social, and personal concerns, we depend on different documents. Therefore, over time, various analytical methods have been developed in order to determine their authenticity, source, and age or to differentiate various papers. In this study a quantitative analytical method for the determination of eight trace level chemical elements (Al, Ba, Fe, Mg, Mn, Pb, Sr, Zn) from document paper samples using inductively coupled plasma‐mass spectrometry (ICP‐MS) was validated and applied. The evaluation of the performance parameters of the method (applicability, fitness for purpose, linearity, working range, limit of detection and limit of quantification, sensitivity, accuracy, and precision) was accomplished. An overview of the validation parameters are presented and discussed in detail. [ABSTRACT FROM AUTHOR]

This article presents the results of an experimental study of waste paper pyrolysis in tubular furnace pyrolysis equipment. Pyrolysis of waste paper has been conducted in different pyrolysis temperatures and heating rates to investigate the product distribution and yields of pyrolysis products. The pyrolysis oil was characterized by elemental analysis and various chromatographic and spectroscopic techniques, which are HPLC, 1 H NMR, FTIR, and UV. The results of spectroscopic and chromatographic analysis show that there are four main different compounds in bio-oil: anhydrosugars, carboxyl compounds, carbonyl compounds and aromatic compounds. [ABSTRACT FROM AUTHOR]

The chromatographic techniques using a flat stationary phase and capillary forces to move the mobile phase appeared centuries ago. The paper stationary phase evolved in silica layers on flat surface. The history of 60 years of planar chromatography is told following the evolution of the technique and focusing on the detection modes. The research prototypes are described as well as commercially available equipment. The author concludes by revealing his view of the future of the technique. [ABSTRACT FROM AUTHOR]

In this study, an attempt is made to understand the chemical and morphological characteristics of Malaysian cultivated kenaf fractions (bast, core, and whole stem). Results based on morphologyand chemical analysis indicate that bast and core fiber fractions in the kenaf are significantly different, although the chemical composition of kenaf is quite similar to the woody mass. In the case of whole stem fibers, it is concluded that the effective length of fibers from the whole stem is reasonably good for the purpose of making printing papers. [ABSTRACT FROM AUTHOR]

Diffusible phosphate ions were collected with iron oxide coated filter paper from planar cuttings of monolith soil samples and coloured directly on the paper by the molybdenum blue method. One sheet of uncoated and one of Fe‐oxide coated filter paper were pressed against a section of soil monolith in a container and immersed in water. After a certain diffusion period, usually 2 to 7 days, the soil was removed and the Fe‐oxide paper was rinsed with water, placed on a plastic sheet and covered with a sheet of filter paper immersed in the colouring reagent. The blue colour appeared within one or a few minutes and showed the sharpest contrasts after approximately 5 min, when it was photographed. This mapping method was used in preliminary studies on the movement of P from fertilizers applied to the soil. Single fertilizer granules applied to the soil surface were detected by pressing the Fe‐oxide paper directly onto the intact soil. Longitudinal cuttings from placed fertilizer rows indicated that the enriched soil was usually no wider than 25 mm, even several months after the application, and the applied P occupied less than 1% of the total volume of the surface soil. The amount of applied P varied from 0.1 to 1.0 g per row metre equalling 8–40 kg P ha‐1with 12.5–25 cm row spacing. [ABSTRACT FROM PUBLISHER]

Buffer capacity appears in a variety of fields, and its approximate calculation is of practical importance for the design of new buffer solutions, being also a quantity related to titrations. The aims of this paper are (i) to devise simple expressions for the buffer capacity and its first derivative for a polyprotic acid, which may be easily extended to a mixture of acids, e.g., universal buffer solutions; (ii) to evaluate overlapping acidity constants (pKa' s) for diprotic acids, from the knowledge of the singular points in the buffer capacity curve; and (iii) at the same time to provide a critical overview of the topic, with some twist of novelty. Hyperbolic functions in analytical chemistry have been surveyed. Conditions for the appearance of singular points in the buffer capacity curve for monoprotic acids and diprotic acids with overlapping pKa values have been established. Methods to evaluate strong and moderate overlapping pKa' s are suggested and applied to literature data. To check the computed values, the acidity constants were also determined by the graphical method of Irving and Rossotti, taken as reference. Results obtained agree well for moderate overlapping pKa' s values, whereas in the case of strong overlapping pKa' s values the agreement is excellent. Limiting Ka1/Ka2 ratio as well as the relation between the acidity constants ratio and the half-values of the formation function, and the problem of distinguishing polyprotic acids from monofunctional ones have been envisaged. An attempt has also been made to derive compact expressions suitable for computer usage for the V = f (pH) derivative curves and buffer capacity curves, taken into account the dilution effects. [ABSTRACT FROM AUTHOR]

Annually, a tremendous amount of mercury is emitted due to anthropogenic activities. As a consequence, occupational and environmental exposure to mercury has drawn broad concern all over the world, and attempts have been sustained to progress analytical methods. The main limitation in exposure assessment is the complexity of biological and environmental samples. Environmental and biological samples need sample preparation to eliminate matrix interferences as well as pre-concentration of the ultra-trace analyte. Among sample preparation methods, considerable attention is devoted to solid-phase extraction (SPE). Porous materials play a vital role in the solid phase extraction procedure for the adsorption and desorption of the target analytes. In this paper, porous materials that were applied for inorganic mercury solid phase extraction were reviewed from 2009 until 2023. Through this study, porous materials were classified and the extraction parameters of each analytical method, including the type of solid phase extraction, porous adsorbent, adsorbent amount, extraction efficiency, real matrices, and detection technique, were clarified. Ultimately, novel attitudes toward green analytical chemistry and innovative ideas were discussed in order to open new horizons. [ABSTRACT FROM AUTHOR]

The chemical industry is acquiring new advancement day by day. Previously, quite massive equipment had been used to do heat transferring tasks, but now the industry has been modernised. Heat Integration is a trending area of study that might be applied in several sectors to redesign processes. Heat Integration alludes to any technique in chemical engineering that results in considerably smaller, greener, and more energy-efficient appliances. Heat Integration aims to improve energy transfer, lowering the equipment's capacity for heat transfer. This paper uses pinch analysis to optimize heat integration and find the best heat-exchange network through case studies. Pinch Technology offers a systematic approach to reducing energy use across all sites and activities. It is feasible to determine the proper alterations to the fundamental process parameters that can result in energy savings by using pinch technology. The Aspen Energy Analyzer tool has been used to compute the heat integration of the case studies. After obtaining the data from the software, they were used in pinch analysis to determine the optimal alternative for the heat exchanger network. [ABSTRACT FROM AUTHOR]

In recent years, interest in using natural fibers in a number of applications especially in biocomposites has grown because they are eco-friendly, lightweight, combustible, nontoxic, low cost and easy to recycle. On the other hand, the lack of good interfacial adhesion and poor resistance to moisture absorption and chemicals make the use of natural fibers less attractive. Chemical treatment of the lignocellulosic fiber can stop the moisture absorption process, clean the fiber surface, chemically modify the surface or increase the surface roughness. Silane treatment of natural fibers is a promising process for improving physical and chemical properties of fibers. The work presented in this article gives insight into the effect of silane treatment on physical and chemical properties of Pinus fibers. Further polymer composites were prepared using urea-formaldehyde as a novel polymer matrix resin. The silane-treated and untreated fibers along with polymer composites have been characterized by various techniques such as scanning electron microscopy (SEM), Fourier transform-infrared spectrophotometry (FT-IR) and thermogravimetric/differential thermal analysis along with DTG studies. Composites prepared were also subjected to the evaluation of different mechanical, physical, and chemical properties. [ABSTRACT FROM AUTHOR]

The present expeditious advancement of green analytical chemistry (GAC) necessitates the establishment of explicit and succinct GAC principles, which may serve as valuable guidance in the adoption of environment friendly laboratory practises. The current ideas of green chemistry and green engineering need modification to effectively address the requirements of analytical chemistry within the context of GAC. The use of multivariate curve resolution (MCR), parallel factor analysis (PARAFAC), self-weighted alternating trilinear decomposition (SWATLD), and unfolded partial least squares/residual bi-linearization (UPLS/RBL) are prevalent approaches for the examination of process data across several application domains like to detect contaminants in water samples. A special emphasis was placed on circumstances that necessitate sophisticated and customised implementations of multivariate curve resolution. This will involve addressing enhancements in pre-processing techniques, arrangements of data from multiple sets, customised constraints, challenges associated with non-ideal noise structure, and deviations from linearity. The study furthermore covers a thorough analysis of case studies and new developments within the discipline, highlighting the efficacy of green analytical chemistry in the identification of pharmaceutical substances in wastewater. This paper examines the principles, methodologies, instrumental analysis, multivariate algorithms, MCR methods, data set configurations, separation techniques and practical applications of GAC for resource minimization and sustainability. [ABSTRACT FROM AUTHOR]

Printed sensors have been explored for more than two decades and have now gained significant interest in real-world applications due to low cost, simple and scalable fabrication processes. These sensors must satisfy the requirement of long-term usage as wearable devices, especially for health monitoring and rehabilitation purposes. However, when such devices are continuously worn on the body or implanted within the body, they may cause unexpected risk to the patient's health. To avoid potential health risks, transition to 'green' strategies has already begun in the research, design and manufacturing of these sensors. This review is dedicated to offering a snapshot of current realization and future prospects of printed sensors through green strategies. The utilization of eco-friendly and cost-effective materials for sensor components and the adoption of various printing methods are summarized. The reusability and multi-detection capability of printed sensors that are within the scope of green analytical chemistry are discussed. [ABSTRACT FROM AUTHOR]

The interactions between organic friction modifiers (FMs) and other additives in a continuously variable transmission (CVT) fluid (CVTF) are investigated with the goal of optimizing friction management of metal pushing V-belt CVTs. Three types of FMs (oleic acid, oleyl alcohol, and glycerol mono-oleate [GMO]) were formulated in poly-α-olefin (PAO) and a fully formulated CVTF, and the friction performance was evaluated in a reciprocating test apparatus (TE77). To estimate their effect on the major frictional components in the CVTs, a steel belt-pulley and a torque converter clutch, the tribotests were carried out with both steel-steel and paper-steel sliding configurations. Then, the posttest materials were assessed by surface analysis techniques to observe the chemical nature of any reacted layers at the surface. The results indicate that the friction on the steel surface was significantly influenced by a combination of the FMs and the CVTF additives as well as the functional group of the FMs. Although oleic acid and GMO typically present greater friction reduction than oleyl alcohol under most conditions, oleic acid did not decrease friction at the steel-steel contact with the presence of the other additives in the CVTF formulation; the friction reduction effect was impaired by the presence of other additives. Surface analysis of the posttest specimens implied that it was interactions with the calcium detergent that inactivated the FM effect of oleic acid. [ABSTRACT FROM AUTHOR]

This special issue of 'Analytical Letters' is devoted to selected papers based on contributions from the 10th Aegean Analytical Chemistry Days (AACD 2016) International Meeting. The first AACD Meeting was held in Izmir-Turkey in 1998 for enhancing the scientific collaboration of analytical chemists from Aegean countries primarily comprising Turkey and Greece, but these series of conferences later evolved into a successful international event covering the entire field of analytical chemistry practiced in almost all countries. Selected papers from most of these conferences were published in the special issues of reputable journals. Specifically in this special edition, the authors have extended their conference proceedings papers and added their latest experimental results. The papers have undergone the standard review process. The AACD 2016 Conference, providing a forum among analytical chemistry researchers from many different countries, was held in Çanakkale, jointly hosted by Çanakkale Onsekiz Mart University (ÇOMU) and Istanbul University (IU). AACD 2016 combined invited lectures, parallel oral sessions and poster presentations, altogether comprising 14 invited lectures, 45 contributed oral presentations and 343 posters, and three company presentations. The selected best 40 posters were orally presented for 5 min at the 'flash poster presentation' session. The Conference Organizers are thankful to the AACD Continuation Committee, invited speakers and all presenters, authors and reviewers who were willing to share their expertise with us by submitting/reviewing the valuable contributions to this special issue, and finally to the Chief Editor of 'Analytical Letters' and Taylor & Francis who handled the complete review process. [ABSTRACT FROM AUTHOR]

This paper examines the identification of chemical elements using mineral analysis, focusing on the controversy surrounding the "tantalum metals" between 1801 and 1866. Of these metals, only tantalum and niobium are still recognised as elements today; the discovery claims of columbium, pelopium, ilmenium and dianium were all retracted or refuted. Despite the theoretical and institutional changes that chemistry underwent during this time, the debates on the tantalum metals point towards a continuity in the identification of metals. For most of the nineteenth century, chemists continued to use the same types of analytical procedures as their mid-eighteenth-century predecessors. These analytical methods enabled the identification of metals based on the chemical behaviour of their compounds, without requiring their isolation in the form of simple substances (that is, as metals). Accordingly, the central questions in all of the debates on the tantalum metals were the correct identification of the properties of compounds and the elimination of impurities, rather than the simplicity of the new metals. The story of the tantalum metals therefore illustrates the fact that, despite the definition of chemical elements as simple substances, the discovery of new (metallic) elements only rarely coincided with the isolation of new simple substances. [ABSTRACT FROM AUTHOR]

Mole fraction solubilities are reported for (2-nitrophenyl)acetic acid dissolved in 1-pentanol, 1-heptanol, 1-octanol, 2-butanol, 3-methyl-1-butanol, 2-pentanol, 4-methyl-2-pentanol, cyclopentanol, 2-ethoxyethanol, 2-propoxyethanol, 2-isopropoxyethanol, 1,4-dioxane, methyl acetate, propyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, tert-butyl acetate, pentyl acetate, methyl butyrate, dimethyl adipate and propanenitrile at 298.15 K. Solubilities were determined using a spectrophotometric method of chemical analysis. Experiment-based Abraham model solute descriptors are calculated for the molecular, monomeric form of (2-nitrophenyl)acetic acid by combining our experimental values with the published solubility data obtained from the published paper by Zhou and co-workers. The calculated solute descriptors describe the observed solubility data to within an overall standard deviation of 0.10 log units. [ABSTRACT FROM AUTHOR]

AbstractFood contact paperboard poses a potential risk of food contamination due to the possible release of chemicals (intentionally added or not), particularly in recycled paperboard. Water extractions were performed, according to wet food procedures, of paperboard samples collected from a manufacturer at the beginning and the end of a recycling production chain. Chemical analysis and hormonal activities in vitro of water extracts were studied. ICP–MS analysis confirmed the presence of 15 trace elements with lower concentrations after the recycling process, with the exception of chlorine. The chromatographic analyses demonstrated that the identified substances in the starting paperboard, before the recycling process, were approximately twice as high as in the end paperboard, after the recycling process. These substances included also natural wood products, chemical additives, and undesirable substances such as phthalates. Two major products (3,5-di-tert-butylphenol and methyl-2-pyrrolidone) were found in the starting and the end paperboard extracts, respectively. Two common substances were identified in both extracts: 2,4-di-tert-buthylphenol and dehydroabietic acid. Evaluation of potential endocrine disruption showed that the starting paperboard extract exhibited oestrogenic and antiandrogenic effects, while these effects nearly disappeared in the end paperboard extract. These results confirmed that the recycling process was effective in removing most of the contaminant substances. [ABSTRACT FROM AUTHOR]

Ginkgo biloba leaf extract (EGBL) is a valuable herbal extract. The main active ingredients are flavonoids, terpene lactones, organic acids and proanthocyanidins. In recent years, there have been many reports on the detection of the above active ingredients. In this paper, the analysis methods of chemical components in EGBL were reviewed, such as ultraviolet spectrophotometry, high-performance liquid chromatography, and quantitative nuclear magnetic resonance. The analysis methods of ginkgolic acids are also reviewed. Based on the current research progress, three suggestions are provided. Firstly, the quality marker research of EGBL needs to be strengthened. Secondly, more bioassay methods for EGBL quality control should be developed. Thirdly, it is necessary to strengthen the detection of proanthocyanidins in EGBL. [ABSTRACT FROM AUTHOR]

Graph theory has found significant use in chemistry, especially in modelling chemical structures. A molecular graph can be represented by a graph where atoms represent vertices and links between these atoms are called edges. Each molecular structure has its own physical properties, such as boiling point, melting point, density, molecular mass, entropy, etc. A topological invariant of a molecular structure is a descriptor that is correlated to certain chemical and biological actions of the chemical compounds. In this paper, we studied the structure of oxide networks, triangular silicate networks, dominating oxide networks and dominating silicate networks in connection to some additive degree-based topological indices. Specifically, the ranking among these networks is also determined with the help of certain multi-criteria decision-making techniques (MCDM). In the end, regression and correlation analyses between their chemical properties and topological indices has been observed. [ABSTRACT FROM AUTHOR]

Regarding Euclidean geometry, introduced the Sombor index and its various types. In graph theory, it is the sum of all pairs of neighbouring vertices. New varieties of Sombor indices are introduced using geometrical interpretation. In this paper, we reviewed recently created Sombor indices for gamma-sheet of boron clusters. In particular, Euclidean geometry introduced the first area-based Sombor index. Perimeters are used to construct the third and fifth Sombor indices, while in terms of angular orientation, the second, fourth, and sixth Sombor indices are determined. Sombor indices can be useful in the analysis of chemical networks because they provide a way to quantify the complexity of the network based on the distances between its constituent molecules. They can be used, for example, to compare the structures of different chemical networks, or to identify regions of high or low connectivity within a network. Degree-based Sombor indices have been used in the analysis of various types of chemical networks, including protein-protein interaction networks, metabolic networks, and gene co-expression networks, among others. They can provide insights into the structure and function of these networks and can be used for tasks such as network clustering, identification of key nodes, and prediction of network behaviour. All the versions of Sombor indices are depend on the degree or valency of bond. First, finding out the degree type of the entire network and then the edge type is also essential to compute the Sombor index, once both types are determined, put the values in the derived formulas, and one can have imported results of Sombor indices. [ABSTRACT FROM AUTHOR]

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The paper reviews the applications of vibrational spectroscopy for the analysis of teeth. A systematic search of literature published between 1990 and 2018 in the following databases: PubMed/MEDLINE, the Cochrane Library, Academic Search Ultimate, and Google Scholar was completed. Peer reviewed original papers and reviews were searched using the following keywords and phrases in different combinations: teeth/tooth, dental, vibrational spectroscopy, near-infrared spectroscopy (NIR), Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), mineralized tissue, hydroxyapatite, geographic, profiling, and characterization. A total of 173 articles matched the inclusion criteria. Of these, 35 studies discussed dental decay; 11 outlined dental maturation and developmental dental defects; 30 assessed demineralization, remineralization, and calcification; 13 analyzed natural and synthetic hydroxyapatite, 50 investigated restorative dentistry and dental medicaments; 22 reported on archeological and anthropological findings, and 12 research studies were conducted in the field of forensics. Despite numerous studies being conducted on the value of vibrational spectroscopy in the characterization of dental tissues, the formulation of geographic profiles through spectroscopic analysis of chemical elements present in teeth has not been attempted hitherto. In particular, information on possible correlations between the chemical dental 'fingerprints' of people residing in the same geographic areas has not been investigated. [ABSTRACT FROM AUTHOR]

Based on the social network analysis (SNA) and the cascading failure model, this paper develops a model of elasticity analysis of the Industrial Symbiosis (IS) network and evaluates the Nanjing Chemical Industry Parks (NCIP) by the metrics of network efficiency and survival rate of the nodes. This paper finds that the NCIP is mainly composed of three major industrial chains, involving the circulation flow of the material, by-products, and energy, and show heterogeneous. Under an intentional attack on the consumer nodes, most of the node's failure cause a chain reaction and bring about changes in network efficiency, and the resilience is not identical accordingly. The network efficiency increases with the augment of the elasticity level, it will not change when reached a certain peak, and the survival rate of the node also increases with the increase of the elasticity level. Therefore, the choice of the optimal elasticity level is helpful to the construction and normal operation of the symbiosis network. At the same time, in order to improve the resilience of the symbiotic network, enterprises should communicate periodically. Because of the ability to find and eliminate the adverse factors, periodic checks are critical for symbiosis between nodes. In order to prevent a network collapse, the NCIP management committee should evaluate the resilience of the IS network regularly, and the government should support the construction of the IS network and give tax subsidies or deductions. [ABSTRACT FROM AUTHOR]

The Eleventh Aegean Analytical Chemistry Days (AACD2018) was held in Chania, Crete, Greece during the period from 25 to 29 September 2018. The scientific framework consisted of 13 oral sessions and 2 poster sessions. Papers in fields such as atomic and molecular spectrometry, mass spectrometry, bioanalytical and clinical analysis, chromatography and separation techniques, electroanalytical methods and biosensors, speciation analysis, sample preparation, chemometrics, quality control/quality assurance and chemical metrology, environmental analysis, food analysis and pharmaceutical analysis were presented during this five-day conference. The social program included a visit to the Botanical Park of Chania and dinner with Cretan dishes and a post-conference one-day excursion to Knossos and Herakleio. During the closing ceremony, it was announced that the next AACD will be organized in Turkey by Professor Sezgin Bakirdere at Yildiz Technical University, Istanbul. [ABSTRACT FROM AUTHOR]

Since their discovery, hydrates have become an important part of the oil and gas industry. The formation and dissociation of hydrates affect their production efficiency. Dispersants can be used to control hydrate formation and are irreplaceable in industrial applications, such as pipeline fluid transportation, gas hydration, and environmental treatment. However, research on the control of hydrate formation/decomposition with dispersants remains inadequate, and industrial applications of the hydrate control technology are still in the initial stage. To understand how dispersants influence natural gas hydrates, this paper summarizes the current experimental research results; describes the formation/dissociation mechanism of dispersants in the reaction process of natural gas hydrate, including kinetics, thermodynamics, and rheology; introduces the promotion–inhibition mechanism of the dispersant; and focuses on analyses of traditional chemical surfactants, solid particles, and new component powders. Based on the research trend of dispersants in the hydration reaction, a review of the existing experimental research and the identified blind spots highlights that there have been numerous studies on traditional chemical dispersants. Thus, it is necessary to promote research on the control of the hydrate reaction with other types of dispersants and on the synergistic effect of dispersants and the environment. [ABSTRACT FROM AUTHOR]

This paper discusses two methodological notions, the concepts Gegenprobe (countercheck) and Gegenversuch (counter-trial), which were widely applied, discussed, relied upon, and defended in German-language writings about empirical inquiry. In the decades around 1800, they were common in physiology; medicine; agriculture; chemistry; various technologies, such as printing, metallurgy, and mining; accounting; and legal and political argumentation. The ubiquity of those concepts signals a broad concern with securing empirical findings and empirical knowledge. Gegenproben and Gegenversuche – the terms as well as the practices – are evidence for the close connection among explicitly knowledge-seeking endeavors and crafts and technologies. Physiological experiments, chemical analyses, agricultural or vaccination trials were indebted to applied and practical procedures of making and assaying. What united these different fields was the fact that the problems that had to be solved were very complex yet at the same time of immediate relevance to everyday lives (like diseases or crops) or highly controversial (like vital forces or spontaneous generation). We know that late eighteenth-century and early nineteenth-century practices of inquiry were firmly embedded in applied, technical contexts; this essay shows that methodological notions were anchored in applied, technical contexts as well. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of numerical and modelling issues based on a simulation of nitrogen-diluted hydrogen lifted flame evolving in a hot co-flow. We apply the large-eddy simulations (LES) method with the so-called 'no combustion model' and concentrate on the impact of chemical mechanisms and various discretisation schemes on the obtained results. The main attention is put to the latter issue in which we analyse to what extent a discretisation method of the convective terms of the scalar equations for the species and enthalpy affects the solutions. We consider eight commonly known total variation diminishing (TVD) schemes and three upwind schemes of the second order. The remaining terms in the scalar equations and all the terms in the Navier–Stokes equations are discretised applying the sixth-order compact difference method. Such an approach makes the discretisation errors of the convective terms the main factor affecting the solutions from the numerical point of view. Prior to the main analysis, the differences caused by the use of various TVD or upwind schemes are highlighted based on a single scalar transport equation with a known analytical solution. The results obtained for the flame are compared to experimental data taken from the literature. It is shown that the differences due to the application of a particular discretisation method are of similar magnitude as the differences between the simulation results and experimental data. Moreover, analysis of the impact of the chemical mechanism showed that observed differences are comparable to these originating from the use of different discretisation methods. [ABSTRACT FROM AUTHOR]

Hot wire Gas Tungsten Arc Welding (GTAW) process is selected for the fabrication of thick section modified 9Cr 1Mo steel components of Steam Generators (SGs) for 500MWe Prototype Fast Breeder Reactor (PFBR) at Kalpakkam, India. During the welding procedure qualification for fabrication of SGs, the 30 mm and 62 mm thick modified 9Cr 1Mo steel welds were subjected to chemical analysis, visual examination, liquid penetrant examination, radiography examination, micro-hardness tests, longitudinal and transverse tensile tests (at ambient temperature and 525 °C), bend tests, drop weight tests and impact tests (at 0 °C and +18 °C). Literature reveals both positive and negative view on the welding of thick-section steel components. Limited information is available in the open literature on the effect of thickness on material properties of modified 9Cr 1Mo steel welds made by the hot wire GTAW method. In view of the above, authors attempted to systematically investigate the influence of thickness on the mechanical properties of modified 9Cr 1Mo steel welds made by the hot wire GTAW process. In this paper, the chemical compositions, hardness, tensile strength, bending strength and impact properties of 30 mm and 62 mm thick welds produced by narrow gap hot wire GTAW process are characterized and compared. It is found that the mechanical properties of 30 mm and 62 mm thick welds are comparable except the impact properties at 0 °C. The impact strength at 0 °C for a 62 mm thick weld was found inferior in comparison with a 30 mm thick weld. [ABSTRACT FROM AUTHOR]

This article presents a new determination method for the analysis of ofloxacin (OFLX) by solid-substrate room temperature phosphorescence (SS-RTP) with filter paper as solid substrate and CdCl2 as heavy-atom salt. Various factors affecting RTP intensity of OFLX, such as heavy-atom effect, pH, and drying time of the sample, were studied in detail. The linear dynamic range (LDR), limit of detection, and RSD were: 1.03 to 411 ng/spot, 0.123 ng/spot and 1.7% for OFLX, respectively. The method was applied to determine OFLX in urine successfully. The recoveries of OFLX in urine were from 94.60% to 105.4%. The pharmacokinetic of OFLX was studied in urine as well. Mean accumulative excretion rate was 77.69%. [ABSTRACT FROM AUTHOR]

The use of rock dust in agriculture has increased worldwide and particularly in Brazil since its regulation by Law 12.890 (2013). However, some inconsistent results in standard chemical analysis of soils amended with rock dust have drawn attention, and among them, cation exchange capacity (CEC). This paper evaluates the increase in sum of bases (SB) and CEC of two soils amended with commercial rock dust (magnesium silicate), measured by four methods: ion exchange resin, potassium chloride (KCl), compulsive exchange and cesium adsorption. The maximum possible increase of SB in the soil was estimated based on the total chemical analysis of the rock dust and compared to the measured CEC results. We concluded the resin method inflated the results, due to the dissolution of rock dust particles by the acid extraction used to recover the adsorbed cations in resin beads. These extra cations caused overestimation of the sum of bases and consequently, of the estimated CEC. Among the methods used, direct CEC methods were more appropriate, as well as the KCl, since it does not employ acid extractions at any step. In addition, calculations based on the total chemical analysis of the rock dust can help to identify some of the cases in which the routine analysis is inflated by the dissolution of rock dust. [ABSTRACT FROM AUTHOR]

The focus of this paper is to conduct research on MHD Casson-Williamson nanofluids flow over an inclined plate with the influence of thermal radiation and Soret-Dufour mechanisms using spectral collocation and statistical analysis. The simultaneous flow of Casson-Williamson non-Newtonian fluids in the presence of a magnetic field, Joule heating, chemical reaction, and viscous dissipation is modelled by utilizing partial differential equations (PDEs). These equations were transformed into coupled nonlinear ordinary differential equations by using an appropriate similarity variable. A numerical and statistical analysis was performed on the transformed equations to obtain significant effects of flow parameters on velocity, temperature, and concentration distributions. An increase in the value of the thermal radiation is observed to increase the fluid temperature, thermal condition, and thermal boundary layer thickness. An increased value of magnetic parameter was observed to decrease the fluid velocity. Due to a magnetic field and the dynamic plastic viscosity, the hydrodynamic boundary layer was observed to decline due to an increase in Casson parameter. The present study was compared with studies in the literature and found in good agreement. [ABSTRACT FROM AUTHOR]

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This document is an introduction to the special issue of Analytical Letters, featuring research papers from the 12th Aegean Analytical Chemistry Days (AACD2023) conference. The conference, which was originally scheduled for 2020 but postponed due to the COVID-19 pandemic, was held at Yildiz Technical University in Istanbul, Turkey. The goal of the conference was to foster scientific collaboration among analytical chemists from Turkey, its neighbors, and the greater Aegean region. The special issue includes 15 original research papers that were selected through a rigorous peer review process. The document expresses gratitude to the organizers, participants, and the editor-in-chief of Analytical Letters for their contributions to the success of the conference and the special issue. [Extracted from the article]

Raman spectroscopy has recently become more popular for the chemical analysis of several types of materials of forensic interest. The Raman technique allows the measurement of the inelastic scattering of light due to the vibrational modes of a molecule when irradiated by an intense monochromatic source such as a laser. Forensic laboratories must often work with small samples in order to determine the type of material and its possible manufacturer for investigatory and evidence purposes. This paper describes the analysis of a color photocopied document for the identification of the particular type of toner used in the generation of the document. [ABSTRACT FROM AUTHOR]

In this paper, the rheological and chemical properties of wheat dough are predicted using deep belief networks. Wheat grains are stored at controlled environmental conditions. The internal parameters of grains viz., protein, fat, carbohydrates, moisture, ash are determined using standard chemical analysis and viscosity of the dough is measured using Rheometer. Here, fat, carbohydrates, moisture, ash and temperature are considered as inputs whereas protein and viscosity are chosen as outputs. The prediction algorithm is developed using deep neural network where each layer is trained greedily using restricted Boltzmann machine (RBM) networks. The overall network is finally fine-tuned using standard neural network technique. In most literature, it has been found that fine-tuning is done using back-propagation technique. In this paper, a new algorithm is proposed in which each layer is tuned using RBM and the final network is fine-tuned using deep neural network (DNN). It has been observed that with the proposed algorithm, errors between the actual and predicted outputs are less compared to the conventional algorithm. Hence, the given network can be considered as beneficial as it predicts the outputs more accurately. Numerical results along with discussions are presented. [ABSTRACT FROM PUBLISHER]

Since the advent of X-Ray fluorescence (XRF) spectrum analysis technology, with its wide range of elemental analysis, rapid, nondestructive analysis characteristics, and better detection accuracy, the workload of semi-quantitative analysis has taken half of the total analysis in contemporary research institutes and university laboratories engaged in material research. In addition, XRF has been widely and efficiently used in analytical chemistry, geological and mineral survey, ecological and environmental monitoring, food and drug detection, archeology and other fields. XRF spectrum processing technology is based on the application of mathematical principles, using reasonable algorithms to optimize the processing of spectrum data to contribute more accurate quantitative analysis of key elements. Over the years, XRF spectrum processing technology has formed a relatively complete set of processes, in each step of spectrum processing, plenty of research work and paper reports have been implemented and developed. This paper mainly reviews the representative algorithms and their progress in spectrum smoothing, background subtraction and overlapping peak decomposition of XRF spectrum analysis technology, analyzes their applications in related fields, summarizes and proposes the development direction of some potential algorithms. [ABSTRACT FROM AUTHOR]

Bioconversion of lignocellulosic wastes to valuable end-products via multi-enzymatic hydrolysis is a potential low costing process for large-scale application in many industrial sectors. Thus, in this study, among thirty local fungal isolates, Aspergillus niger which gave the highest cellulase production, was identified under the accession number MZ062603 in GeneBank. Three types of pre-treatments (0.0–0.7%) acid, (0.0–2%) alkali, and (70–90 °C) hot water were applied to increase wheat straw (WS) digestibility by A. niger, and 1% NaOH treated WS was superior to the other pre-treatments (acid and hot water). During solid-state fermentation, the total cellulolytic activity of [filter-paper cellulase (FPase), carboxy-methyl cellulase (CMCase), and β- glucosidase (βGase)] increased about 2.8-fold. While reducing sugar was increased by 3.1 times. The optimum values of total cellulases activities and reducing sugar (8907.2 and 92.4 mg/gds) were obtained after 3 days of incubation at 30 °C and pH 5.2 at 75% v/w moisture using 3 days old inoculum (106 spores/mL/gds). The WS substrate which was subjected to alkali pre-treatment subsequent to fungal bioconversion was varied in its chemical composition and detailed structure compared to the raw and alkali pre-treatment ones as indicated by its chemical analysis, Scanning electron microscopy (SEM) observation, Fourier Transform Infra-red Spectroscopy (FTIR), and X-Ray Diffraction (XRD). All these analyses revealed that the lignocellulosic matrix was completely destroyed after the fungal treatment. [ABSTRACT FROM AUTHOR]

The primary motivation of this paper is to report the effects of n-butanol addition (5, 20 and 35% by volume) to diesel fuel on regulated and polycyclic aromatic hydrocarbon (PAH) emissions of a diesel engine. PAH samples were quantified using rigorous analytical chemistry procedures to determine total PAHs, PAH dispersion and PAH toxicity. In comparison with diesel fuel, all n-butanol blends (DBu5, DBu20, and DBu35) reduced nitrogen oxides (NOx) emissions by 6.77%, 9.59%, and 20.08% and total PAH emissions by 66.86%, 75.33%, and 80.98%. In terms of the relative distribution of PAHs, a significant decrease was recorded in higher cyclic PAHs such as Pyrene, Benzo[a]anthracene, Chrysene, Benzo[k]floranthene, Benzo[a]pyrene for all blends. Similarly, the amount of the toxicity of the PAH emissions also decreased by 11.66%, 87.53%, and 67.28% with DBu5, DBu20 and DBu35 blends, respectively. With the addition of n-butanol to the diesel fuel, total PAH emissions were detected below the Occupational Safety and Health Administration's (OSHA)-Permissible Exposure Level. Overall, it was demonstrated that n-butanol addition to diesel fuel significantly reduced PAH formation which is helpful to prevent wet stacking, and prolong the operating time of the diesel engine especially at low loads or cold operating conditions. [ABSTRACT FROM AUTHOR]

The most commonly used technique to prepare samples for the analysis of wine volatile is the headspace solid-phase microextraction (HS-SPME). This method has gained popularity in last few years, as it is a unique solventless preparation technique. In this paper, a summary of recently published studies using HS-SPME for the analysis of wine aromas, with special emphasis on the method developed, has been compiled. Several papers are discussed in detail, mainly with respect to the SPME conditions used. A brief summary of the reviews related to HS-SPME analysis is given and discussed. Several parameters affecting the HS-SPME, such as the salt concentration and the agitation conditions, are used in the same way as used in several papers. The HS-SPME extraction proved to be sufficiently sensitive to satisfy legislative requirements related to low detection and quantification limits as well as method accuracy and precision requirements. However, in order to achieve the best performance and precision, the protocol needs to be optimized for each case. The effect of different parameters must be well characterized to ensure correct extraction and desorption to ensure the transfer of extracted compounds into the analytical system. The operating parameters, such as time, temperature, and agitation, must then be kept constant for all the samples. [ABSTRACT FROM AUTHOR]

In recent years, the application of liposomes in the field of analytical chemistry has attracted more and more attention. In this paper, the preparation and characterization of liposomes are briefly summarized, and the research and application of liposomes in organic and biological substances analysis are mainly reviewed, including immobilized liposome chromatography, liposome capillary electrophoresis, liposome application in electrochemical analysis, and optical analysis. The future developments of liposomes in the assay are also prospected. [ABSTRACT FROM AUTHOR]