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This paper presents the oxygen sensing response of a resistive sensor employing sensing layers based on a binary matrix nanocomposite such as carbon nanohorns/polyvinylpyrrolidone and oxidized carbon nanohorns/polyvinylpyrrolidone, both at 9/1 w/w/ mass ratio. The sensing structure comprises a silicon substrate, a SiO2 layer, and interdigitated transducers (IDT) electrodes, on which the sensing layer is deposited via the drop-casting method. The thin film's morphology and composition are examined through scanning electron microscopy (SEM) and RAMAN spectroscopy. The oxygen sensing capability of each carbon nanohorns composite-based sensing layer was analyzed by applying a current between the two electrodes and measuring the voltage difference when varying the O2 from 0% to 100% in dry nitrogen. Experiments reveal that in the case of pristine carbon nanohorns / PVP matrix nanocomposite, the resistance increases. In contrast, in the case of oxidized carbon nanohorns, the resistance of the sensitive layer decreases with increasing oxygen concentration. The results are explained by considering the differences from structural and electrical points of view between the two types of nanocarbonic materials. Moreover, previous resistive RH sensing measurements in humid air and humid nitrogen using oxidized carbon nanohorns as sensing elements proved helpful in better understanding and discriminating between the chemisorption/physisorption of oxygen molecules at carboxyl functional sites and graphitic carbon sites. [ABSTRACT FROM AUTHOR]

The wastewater treatment process significantly decreases the negative impact of the effluent on human health compared to the influent. This probabilistic study, based on mathematical formulas, which does not involve clinical studies, investigates the impact of polluting chemical elements on health, which may be higher or lower, depending on other direct or indirect factors. The conclusions from this study were (1) wastewater (the effluent, which falls within legal limits) cannot be used for domestic consumption, much less as drinking water; (2) regarding dermal absorption, this can only be possible if people use the wastewater (influent/effluent) for recreational purposes (bathing, fishing, etc.). If this were theoretically possible, the risks related to the respective water matrices can be much higher because in this study only five heavy metals (Cd, Pb, Cu, Ni, and Zn) found in the international legislation in the categories of substances with carcinogenic risk, were investigated in the wastewater, and it may also contain other substances with different risk degrees. In the future studies will be investigated the health risk assessment gradient related to the effluent from the point of discharge of the wastewater on the flow of the natural receiver. [ABSTRACT FROM AUTHOR]

Chlorophyll-a is the pigment whose concentration is an important indicator for the development of microalgae biomass. This study aims at evaluating the concentration of chlorophylls in the biomass of granular activated algae, using acetone and 90% ethanol for the extraction procedures applied. Concentrations of chlorophyll a, b and c were determined by applying three calculation types: methods proposed by Jeffrey and Humphrey for the extracts in acetone, Ritchie method for ethanolic extracts, and monochromatic method with acidification for ethanolic extracts. Experimental findings show that the solvent 90% ethanol is more efficient than acetone for extracting chlorophyll from biomass of granular activated algae. Also, by comparing results obtained by the two methods proposed for ethanolic extracts, it was found that the values obtained through the acidification method are influenced by the volume of hydrochloric acid added to the organic chlorophylls extract. [ABSTRACT FROM AUTHOR]

The present paper is focused on the microclimatic investigation and weather-climatic phenomena matrix assessment, which can be generated for heritage objectives at different spatial and temporal resolutions, correlated with physicochemical analysis of the particulate matter (PM2.5-10). In the literature the importance of atmospheric PM monitoring in the proximity of monuments is not yet sufficiently highlighted. In this respect, the microclimatic investigation of the Tropaeum Traiani Monument (Adamclisi, Romania) was performed to assess the suitability of a closed environment, located outdoors, according to the conservation requirements of heritage materials. The monitoring campaigns (four seasons, e.g., from summer of the year 2018 to spring of the year 2019) were carried out by non-invasive measuring equipment. The collected data were used to investigate the hygrothermal and chemical behavior inside and outside of Tropaeum Traiani Monument, built in 109, to assess the risks on the oldest structural material. Principal component analysis (PCA) was performed by IBM SPSS Statistics software to assess the similarities between the microclimatic parameters. [ABSTRACT FROM AUTHOR]

This work attempts to show the usefulness of vibrational spectroscopy (i.e., FTIR and Raman) in the analysis of major components of the original structure materials of a heritage monument (Tropaeum Traiani, Adamclisi). The features of materials and indoor microclimatic variables (i.e., temperature and relative humidity), on the periods of the monitoring campaigns, were considered. As the conservation must make sure about the physicochemical and structural aspects of the materials, assessment of the environmental impact, deterioration processes and characterization of ancient building materials are useful to understand the chemical evolution in the past, predict the various trends in the future, choose the suitable restoration methods to preserve their present state, and even to describe the alteration process of materials and modification through time. The surface of original structure materials used until present seems not to be affected at major scale by the indoor microclimate variables. But even high recorded relative humidity levels promote the occurrence of amorphous calcium carbonate, calcite, aragonite and vaterite highlighted by vibrational spectroscopy data (i.e., FTIR and Raman), as a first effect, the development of biological organism can be enhanced, depending on the characteristics of the substrate. Second, atmospheric pollutants can be dissolved easier in the humidity existing in the porous material, and lastly, if the waterflow inside the stone is not homogeneous, cracks could appear due to differences in permeability. [ABSTRACT FROM AUTHOR]

The study presents the effect of adding p-tert-butylcalix[4]arene, benzo ether crowns and their equimolecular mixture in the organic phase on the interfacial tension for the chloroform water interface. It was found that addition of macrocyclic ligands to the organic phase has different effects on the interfacial tension. The higher the number of oxygen atoms in the ethereal ring of the benzo crown ethers, the higher the values of interfacial tension, while same modification of the ethereal ring produces an opposite effect in the case of amino benzo ethers, indicating different arrangements of molecules in the interface. The simultaneous presence of p-tert-butylcalix[4]arene and benzo crown ethers in the interface leads, in some situations, to significant changes in the interfacial tension values, a phenomenon explained by the modification of the macrocyclic ligands assembly in the interface. Also, composition of the aqueous phase influences the value of measured interfacial tension, type of the alkaline cation from the aqueous solution leading to different behavior of macrocyclic ligands in the interface. [ABSTRACT FROM AUTHOR]

Supramolecular chemistry, one of the topical fields of contemporary chemistry, deals sometimes with subtle interactions, sophisticated molecules, and huge molecular aggregates. Furthermore, many terms such as molecular self-assembly, mechanically-interlocked molecular architectures, container-molecule, and cryptand, may sound abstract and sometimes discouraging. The purpose of this paper is to show how a chemistry teacher can scrutinize supramolecular chemistry in terms of everyday chemistry. Four directions which can help to a better understanding of this domain are identified and analyzed. Simple synthetic procedures for most of the supramolecular receptors, the occurrence of supramolecular chemistry in Nature, the connection between supramolecular chemistry and life itself (self-assembly of nucleic acid bases) are useful examples for emphasizing the versatility of this domain. Last, but not least, the presence of supramolecular chemistry in food, drugs, drinks, tobacco-based products, homecare products, cosmetics, are relevant examples of how this concept is present in everyday life. [ABSTRACT FROM AUTHOR]

Chemical compounds from plant extracts offer unlimited opportunities as cosmetic additives due to their availability and chemical diversity. Increasing demand for chemical compounds from different classes made the plant extracts, edible plant extracts in particular, useful for cosmetic products. The profile of bioactive compounds contained by the so-called natural cosmetic products may be different according to the characteristics of the plant extracts used in their fabrication processes. The study proposes a comparative analysis of several characteristics of grape extracts obtained by solid-liquid extraction, using water as solvent, with and without ultrasonation. Extracts obtained from four red grape varieties harvested at maturity from two types of vineyards, ecological and traditional, were analyzed. Total flavonoid contents, pH and conductivity were measured; correlations of these properties with extraction method, grape variety and vineyard type were envisaged as well. It was concluded that slight differences may occur in extracts aciditiy and conductivity of studied red grape extracts, as well as in the total flavonoids contents, and that the use of the ultrasound power during the applied extraction procedures does not have a significant influence. The vineyards type however showed some influence on the studied extracts properties. [ABSTRACT FROM AUTHOR]

Even though chemistry is sometimes recognized as the core science due to its importance in many fields of our life, it has a bad reputation in school, being classified as an abstract and boring science. The paper outlines the journey of chemistry from central science to chemofobia and how should school and teachers can address this. The paper emphasizes how chemophobia is amplified and suggests that in most cases it is not interrelated with difficulties encountered in learnig of chemistry. Some of the most common misconceptions related to chemophobia such as "many cancers are related to synthetic chemical compounds", "food and collor additives are very toxic", "the food is contaminated with a lot of dangerous chemicals", etc., are discussed and it was demonstrated their little supportive evidence. The paper highlights the importance of school (chemistry teachers, in particular) to clarify the fundamental terms such as natural or synthetic chemical compounds, food additives, drugs, artificial sweeteners, etc. [ABSTRACT FROM AUTHOR]

Even though the Internet is an enormous online library, discrimination between the accurate, scientific data and misleading information can be a serious issue even for a well- trained person. Unfortunately, a plethora of false information related to the chemical compounds with major impact on our lives is distributed on online environment. The main purpose of this paper is to review a few of the most encountered urban myths related to the "dangerous, carcinogenic, toxic" substances or, on the contrary, "panacea compounds". Thus, the paper does analyze the popular (unconfirmed) facts and statements versus scientific evidence covering hot topics such as parabens, monosodium glutamate (MSG), Saccharin, amygdalin and Laetril, resveratrol, and rheosmin (raspberry ketone). Furthermore, the paper emphasizes the role of the high - school teachers in ensuring that students do access the most relevant and valid sources of information, while providing specific tools to discriminate between accurate, scientific data and false and dangerous statements with negative consequences from the educational perspective and beyond. Last but not least, the paper highlights the importance of using reliable sources of information from well-established institutions such as the EFSA (European Food Safety Authority, www.efsa.europa.eu), EMA (European Medicine Agency, http://www.ema.europa.eu), FDA (Food and Drug Administration, www.fda.gov), the EPA (Environmental Protection Agency, www.epa.gov), the IARC (International Agency for Research on Cancer, www.iarc.fr), the ANM (National Medicines Agency, http://www.anpm.ro), WHO (World Health Organization, www.who.int), EMA (European Medicine Agency), Mayo Clinic. [ABSTRACT FROM AUTHOR]

Bone tissue sampled from a patient suffering from osteoarthritis was characterized using X-ray diffraction and nanoindentation. Structural and chemical analysis of bone and cartilage samples showed their crystalline and/or amorphous character, and presence of crystalline phases such as hydroxyapatite Ca5(PO4)3(OH), monetite CaHPO4 and brushite CaPO3(OH).2H2O in various proportions was found. Nanometric crystallite sizes in the range of 1.68 to 17.61 nm were found in the crystalline phases identified in studied bones. Measurements of microhardness (2 MPa) and Young modulus (21 MPa) on cartilage samples along with the anatomical axis of the tibia showed one order differences compared to parameters of cartilage samples measured perpendicular to the long axis of the tibia (57 MPa for microhardness and 368 MPa for Young modulus). Correlations of measured parameters with orthopedic pathology were suggested. [ABSTRACT FROM AUTHOR]

The effect of the simultaneous presence of lead and magnesium in hydroponic culture on the growth of Salix alba offshoots was studied. Present study used biological material collected from area of Targoviste city, specifically from the bank of the Ialomita River. Willow offshoots, having the same number of internodes and same diameter, were collected. The hydroponic cultures were made with three water types as hydroponic substrate, tap water, flowing water and water, lead and magnesium being added in gravimetric ratios of 0.01%, 0.1% and 0.5% (w / w). Experiments were mounted so that each glass with a certain composition of hydroponic culture held three willow offshoots in the same conditions; environmental parameters (temperature °C and relative humidity %) were continuously monitored; sampling procedure was followed for further analytical investigations. As a general conclusion, there was a smaller number of leaves and roots when concentration of lead and magnesium was 0.5%. The type of water had an important influence on the development of Salix alba offshoots during experiments. Guaiacol peroxidase activity was experimentally determined at the end of the fourth day of willow monitoring. This time was considered enough for the hydroponic system to reach equilibrium. The graphical representation of guaiacol peroxidase activity shows the same pattern with a small difference when tap water was used as solvent. At the end of experiment, solid material (roots and leaves separately sampled) was dried at 60°C some hours and then digested in a mixture of oxygenated water (H2O2 30%) and nitric acid (HNO3 67%). Liquid homogeneous samples obtained were measured by atomic absorption spectrometry (AAS), concentrations of zinc, cadmium, and selenium was determined. Thus, presence of significant quantities of magnesium and lead was tested for the influence on levels of cations with different reactivity reactivity, as zinc, cadmium and selenium. [ABSTRACT FROM AUTHOR]

Alkyd resin coatings are applied, mostly, due to their versatility, proper stability, and good compatibility with other modifying agents like curing agents, antioxidants, and nanoparticles that allow manufacturing resins with improved properties. The proportions between mixture components as well as the control of curing process parameters influence the final features of the final product. In this study, three types of alkyd resins consisting of phthalic anhydride, pentaerythritol, benzoic acid, propylene glycol as well as three different type of vegetable oil, were investigated. The content of vegetable oil was the same. In all alkyd formulations, for the curing process, melamine resin was used and the resulted mixture was tested for thermal and radiation stability. Epoxy resin, acrylamide, and SiO2 and Al2O3 nanoparticles were used for the improvement of the material. The structural change of obtained polymers was investigated by IR spectroscopy with attenuated total reflection (ATR) and conclusions about their stability were drawn. The thermal stability of irradiated and non-irradiated samples was investigated by chemiluminescence in stationary air atmosphere, as well. [ABSTRACT FROM AUTHOR]