Carbon Elemental Analysis Research Articles

Sedimentary Environment and Organic Matter Accumulation of Continental Shales in Xiahuayuan Formation in Xuanlong Depression, Yanshan Area

The shale sedimentary environment is crucial for evaluating shale gas reservoirs and sweet spot zones. The Xiahuayuan Formation in the Xuanlong Depression of the Yanshan area is an important exploration and development region for shale gas due to its multi-layer dark shale. The paleosedimentary environment and organic matter accumulation mechanism of organic-rich shale were discussed through geochemical methods such as total organic carbon (TOC) content and elemental analysis. The results indicate that the shale exhibits a high TOC content. The Mo content and the P/Al and P/Ti ratios indicate that the primary productivity of the ancient lake is high. The Ceanom, V/(V + Ni) ratio and MoEF-UEF covariation model reveal that the sedimentary environment of shale is characterized by anoxic conditions. The ratios of K/Al and Ti/Al suggest significant variations in the input of fine-grained clay clastics and terrigenous clastics. The Ca/(Fe + Ca) and Sr/Ba ratios suggest that the paleowater was a freshwater environment. The paleoclimatic conditions, as indicated by CIA, Sr/Cu, and C-value, suggest a range from semi-humid to humid. The ratios of Rb/K and Mn/Ti reflect that the water primarily existed in a shore–shallow lake environment. The correlation analysis between organic matter accumulation and sedimentary environment parameters indicates that the primary factors influencing the organic matter accumulation in the Xiahuayuan Formation shale are redox conditions, terrigenous clastic input, paleoclimate conditions, and paleowater depth. The organic matter accumulation is characterized by a “preservation condition” pattern. This study provides theoretical support for the accumulation mechanism, potential evaluation of resources, and optimal selection of favorable regions for Jurassic shale gas in the Xuanlong Depression.

CO2 Loss into Solution: An Experimental Investigation of CO2 Electrolysis with a Membrane Electrode Assembly Cell.

In pursuit of commercial viability for carbon dioxide (CO2) electrolysis, this study investigates the operational challenges associated with membrane electrode assembly (MEA)-type CO2 electrolyzers, with a focus on CO2 loss into the solution phase through bicarbonate (HCO3 -) and carbonate (CO3 2-) ion formation. Utilizing a silver electrode known for selectively facilitating CO2 to CO conversion, the molar production of CO2, CO, and H2 is measured across a range of current densities from 0 to 600 mA/cm2, while maintaining a constant CO2 inlet flow rate of 58 mL/min. The dynamics of CO2 loss are monitored through measurements of pH changes in the electrolyte and carbon elemental balance analysis. Employing the concept of conservation of elemental carbon, a chemical reaction analysis is conducted, identifying the critical role of the hydroxide (OH-) ion. At lower current densities below 125 mA/cm2, where CO2 reduction predominates, it is observed that CO2 loss is proportional to current density, reaching up to 0.18 mmol/min, and directly correlates with the rate of OH- ion production, indicative of HCO3 -/CO3 2- ion formation. Conversely, at higher current densities above 450 mA/cm2, where hydrogen evolution is the dominant process, CO2 loss is shown to decouple from the OH- ion production rate with a constant limit condition of 0.12 mmol/min, regardless of the current density. This suggests that electrolyte-induced cathode flooding restricts CO2 access to cathode sites. Additionally, pH change in the electrolyte during the electrolysis further infers differing ion populations in the CO2 reduction and hydrogen evolution regimes, and their movement across the membrane. Continued monitoring of the pH change after the cessation of electricity offers insights into the accumulation of HCO3 -/CO3 2- ion at the cathode, influencing salt formation.

Synthesis of innovative Daphne mucronata extract/Cu-MOF/PVA-PVP nanofiber as high-performance anticancer and antimicrobial agent

Nanofibers’ unique physical properties include mechanical strength, compressive strength, and high specific surface area, making them highly valuable and significant. Nanofiber can be containing nano compounds such as metal nano oxides, metal–organic framework, etc., as well as plant extracts. Plant extracts have had a special place in human life since the past and used in traditional medicine. The synthesis of new nanofibers containing plant extracts and metal–organic framework was the idea that we focused on it. For this purpose, Daphne mucronata extract and copper metal–organic framework, considering the high biological properties were used. For the synthesis of Daphne mucronata extract/Cu-MOF/PVA-PVP nanofiber, electrospinning method and polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) were used. The final product’s structure was examined and verified using XRD (X-Ray diffraction analysis), EDAX (Energy dispersive X-ray analysis), CHNO EA (Carbon, hydrogen, nitrogen, and oxygen elemental analysis), SEM (Scanning electron microscope images), BET (Brunauer-Emmett-Teller theory), FT-IR (Fourier transform infrared spectroscopy), contact angle (Hydrophilic properties), mechanical strength and compressive strength. The specific surface area of the synthesized nanofiber and the diameter size of the synthesized particles were observed to be area 1102 m2/g and 80 nm, respectively. High hydrophilic properties (29°), high flexural strength (17.3 N/mm2), and high compressive strength (65.7 N/mm2) were among other characteristics of the synthesized nanofiber. Biological properties of the synthesized nanoparticle, such as anti-skin cancer, anti-bacterial, and anti-fungal properties, were tested. In the anticancer study, IC50 was 21 μg/mL, and in the antimicrobial studies (antibacterial and antifungal activity), the MIC was between 2 μg/mL and 64 μg/mL. Thus, the synthesized nanofiber can be incorporated as a bioactive compound in the medical industry, such as being utilized as bioactive medical bandages after other tests have been completed.

Temperature-modulated interactions between thermoresponsive strong cationic copolymer-brush-grafted silica beads and biomolecules

Thermoresponsive polymer brushes have attracted considerable research attention owing to their unique properties. Herein, we developed silica beads grafted with poly(N-isopropylacrylamide (NIPAAm)-co-3-acrylamidopropyl trimethylammonium chloride (APTAC)-co-tert-butyl acrylamide (tBAAm) and P(NIPAAm-co-APTAC-co-n-butyl methacrylate(nBMA)) brushes. The carbon, hydrogen, and nitrogen elemental analysis of the copolymer-grated silica beads revealed the presence of a large amount of the grafted copolymer on the silica beads. The electrostatic and hydrophobic interactions between biomolecules and prepared copolymer brushes were analyzed by observing their elution behaviors via high-performance liquid chromatography using the copolymer-brush-modified beads as the stationary phase. Adenosine nucleotides were retained in the bead-packed columns, which was attributed to the electrostatic interaction between the copolymers and adenosine nucleotides. Insulin was adsorbed on the copolymer brushes at high temperatures, which was attributed to its electrostatic and hydrophobic interactions with the copolymer. Similar adsorption behavior was observed in case of albumin. Further, at a low concentration of the phosphate buffer solution, albumin was adsorbed onto the copolymer brushes even at relatively low temperatures owing to its enhanced electrostatic interaction with the copolymer. These results indicated that the developed thermoresponsive strong cationic copolymer brushes can interact with peptides and proteins through a combination of electrostatic and temperature-modulated hydrophobic interactions. Thus, the developed copolymer brushes exhibits substantial potential for application in chromatographic matrices for the analysis and purification of peptides and proteins.

Analysis of PM2.5, black carbon, and trace metals measurements from the Kansas City Transportation and Local-Scale Air Quality Study (KC-TRAQS)

ABSTRACT Communities near transportation sources can be impacted by higher concentrations of particulate matter (PM) and other air pollutants. Few studies have reported on air quality in complex urban environments with multiple transportation sources. To better understand these environments, the Kansas City Transportation and Local-Scale Air Quality Study (KC-TRAQS) was conducted in three neighborhoods in Southeast Kansas City, Kansas. This area has several emissions sources including transportation (railyards, vehicles, diesel trucks), light industry, commercial facilities, and residential areas. Stationary samples were collected for 1-year (October 24, 2017, to October 31, 2018) at six sites using traditional sampling methods and lower-cost air sensor packages. This work examines PM less than 2.5 μm in diameter (PM2.5), black carbon (BC), and trace metals data collected during KC-TRAQS. PM2.5 filter samples showed the highest 24-h mean concentrations (9.34 μg/m3) at the sites located within 20–50 m of the railyard. Mean 24-h PM2.5 concentrations, ranging from 7.96 to 9.34 μg/m3, at all sites were lower than that of the nearby regulatory site (9.83 μg/m3). Daily maximum PM2.5 concentrations were higher at the KC-TRAQS sites (ranging from 25.31 to 43.76 μg/m3) compared to the regulatory site (20.50 μg/m3), suggesting short-duration impacts of localized emissions sources. Across the KC-TRAQS sites, 24-h averaged PM2.5 concentrations from the sensor package (P-POD) ranged from 3.24 to 5.69 µg/m3 showing that, out-of-the-box, the PM sensor underestimated the reference concentrations. KC-TRAQS was supplemented by elemental and organic carbon (EC/OC) and trace metal analysis of filter samples. The EC/OC data suggested the presence of secondary organic aerosol formation, with the highest mean concentrations observed at the site within 20 m of the railyard. Trace metals data showed daily, monthly, and seasonal variations for iron, copper, zinc, chromium, and nickel, with elevated concentrations occurring during the summer at most of the sites. Implications: This work reports on findings from a year-long air quality study in Southeast Kansas City, Kansas to understand micro-scale air quality in neighborhoods impacted by multiple emissions sources such as transportation sources (including a large railyard operation), light industry, commercial facilities, and residential areas. While dozens of studies have reported on air quality near roadways, this work will provide more information on PM2.5, black carbon, and trace metals concentrations near other transportation sources in particular railyards. This work can also inform additional field studies near railyards.

Nanocomposite based on hydroxyapatite and boron nitride nanostructures containing collagen and tannic acid ameliorates the mechanical strengthening and tumor therapy

The increase in life expectancy has led to a concerning decline in the body's functional capacity, particularly in bone health, where decreased resistance and increased fracture susceptibility pose significant challenges in orthopedics. While traditional bone grafting methods have drawbacks, synthetic materials, particularly hydroxyapatite (HA), offer promising alternatives due to their biocompatibility and osteoconductive properties. However, HA's mechanical limitations necessitate reinforcement, with boron nitride nanostructures emerging as a particularly effective option, enhancing fracture resistance and combining HA with collagen, further mimicking natural bone composition, offering several benefits. Moreover, crosslinking agents like tannic acid (TA) improve collagen's stability and introduce therapeutic benefits. Therefore, the present work aimed to synthesize an innovative nanocomposite formed by hydroxyapatite, boron nitride nanostructures, collagen, and tannic acid. The nanocomposites obtained were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TGA), elemental analysis of carbon, hydrogen, and nitrogen (CHN), and scanning electron microscopy (SEM). Mechanical tests of Vickers hardness, nanoindentation, tensile, and DMA demonstrated an increase in the mechanical resistance of the nanocomposites, thus corroborating their promising character. A controlled drug release test showed that the system could be used for antibiotic (ciprofloxacin) delivery, further expanding its function. Biological cell viability assays reported that the system is not toxic to healthy cells and is harmful to tumor cells, thus demonstrating the antitumor nature of TA. Therefore, integrating HA, BN nanostructures, collagen, and TA into a multifunctional nanocomposite, a novel approach in orthopedic biomaterial design is offered as a promising solution to address various bone-related challenges.

A critical comparison of the main characterization techniques for microplastics identification in an accelerated aging laboratory experiment

Many studies have reported the occurrence of microplastics in different environmental compartments, through the description of their morphological characteristics and chemical identification, obtained mainly by spectroscopic techniques. However, the scientific community still lacks the implementation of standardized analytical methods that aim to assess not only the identification of the particle, but also its stage of degradation. It is understood that this information would be extremely useful in helping elucidate the main sources of pollution and contributing to strategies and mitigating measures for the management of solid waste and microplastics in the environment. In this respect, the aim of this study was to evaluate the efficiency of Fourier-transform infrared spectroscopy, Raman spectroscopy, carbon elemental analysis coupled with mass spectrometry, and scanning electron microscopy with energy dispersive X-ray spectrometry for the characterization of virgin and aged polyethylene and polypropylene microplastics samples. The degraded samples were subjected to accelerated aging in a QUV chamber in accordance with American standard for measuring accelerated weather testing (ASTM G-154). This work discusses the efficiency and limitations of each technique for the detailed chemical characterization of microplastic samples collected from the environment.

LIBS analysis of elemental carbon and fixed carbon in coal by dual-cycle regression based on matrix-matched calibration

The accuracy of LIBS coal quality detection was improved after matrix calibration, and the coal was evaluated by using the carbon dioxide emission level and net calorific value.

Applicability of aethalometers for monitoring diesel particulate matter concentrations and exposure in underground mines

Occupational exposure to diesel exhaust is regulated by legislation in Europe owing to its carcinogenic effects on humans. In underground mines, exposure to diesel exhaust requires regular monitoring. In this work, we investigate the usage of aethalometer AE33 and portable micro-aethalometer MA200 to assess occupational exposure to diesel exhaust in two underground mines. These instruments provide continuous data on wavelength-dependent particle light absorption, and based on this, equivalent black carbon (eBC) particle concentrations and potential sources. Both aethalometers correlated well with the thermal-optical elemental carbon analysis. Time-resolved aethalometer data revealed work-activity-dependent eBC concentration patterns that can be beneficial for identifying work phases that are significant for occupational exposure. In particular, high eBC peak exposures were observed for workers near load haul dumping areas. The diesel soot mass absorption cross-sections determined were similar for both mines. The absorption Ångström exponent determined from the aethalometer data was suitable for detecting and assessing the contributions of other potential sources to eBC concentrations, such as tobacco smoke, which is often prevalent in work environments. Overall, the portable micro-aethalometers proved to be suitable for monitoring occupational diesel exhaust exposure and can be useful for designing targeted exposure prevention measures in mining environments.

Application of an Ultra-Low-Cost Passive Sampler for Light-Absorbing Carbon in Mongolia

Low-cost, long-term measures of air pollution concentrations are often needed for epidemiological studies and policy analyses of household air pollution. The Washington passive sampler (WPS), an ultra-low-cost method for measuring the long-term average levels of light-absorbing carbon (LAC) air pollution, uses digital images to measure the changes in the reflectance of a passively exposed paper filter. A prior publication on WPS reported high precision and reproducibility. Here, we deployed three methods to each of 10 households in Ulaanbaatar, Mongolia: one PurpleAir for PM2.5; two ultrasonic personal aerosol samplers (UPAS) with quartz filters for the thermal-optical analysis of elemental carbon (EC); and two WPS for LAC. We compared multiple rounds of 4-week-average measurements. The analyses calibrating the LAC to the elemental carbon measurement suggest that 1 µg of EC/m3 corresponds to 62 PI/month (R2 = 0.83). The EC-LAC calibration curve indicates an accuracy (root-mean-square error) of 3.1 µg of EC/m3, or ~21% of the average elemental carbon concentration. The RMSE values observed here for the WPS are comparable to the reported accuracy levels for other methods, including reference methods. Based on the precision and accuracy results shown here, as well as the increased simplicity of deployment, the WPS may merit further consideration for studying air quality in homes that use solid fuels.

Quinolone Tethered 1,2,3-triazole Conjugates: Design, Synthesis, and Computational Docking Studies on New Heterocycles as Potent Antimicrobial Targets

Abstract: The synthesis and biological properties of molecules simultaneously comprising various heterocycles, such as fused 2-quinolones and 1,2,3-triazoles, have been evaluated as a part of our ongoing research in medicinal and organic chemistry. We were successful in developing a synthetic procedure for 1,2,3-triazole substituted quinolone derivatives. Infrared, proton, and carbon nuclear magnetic resonance, mass spectroscopy and elemental analysis were used to characterise the structures of the recently synthesised triazole derivatives. From screening results, all the compounds demonstrated increased antibacterial action against both Gram-positive and Gram-negative bacteria. Moreover, 1,2,3-triazoles linked to tert-butyl benzyl (3a), trifluoromethyl benzyl (3b), 3-chlorobenzyl (3c), 4- hydroxy-3-nitrobenzyl (6b), 4-hydroxy-4-trifluoromethylbenzyl (6d), and 4-hydroxy-2,4- difluorobenzyl (6e) compounds showed promising antibacterial and antifungal activities with MICs values of 1.07-4.33 μg/mL. The prepared ligand 4-hydroxy-2,4-difluoro benzyl-1,2,3-triazole (6e) exhibited the highest docking score of -6.34 kcal/mol and showed interacting amino acid residues ArgB:1122, MetB:1121, AspB:1083, TryB:1087, AlaB:1118, AlaB:1120, GluB:1088, GlyB:1117, SerB:1084, and AlaB:1119 within the active site of 2XCT. Final scaffolds were further evaluated for their ADMET and physicochemical properties by using ADMETlab2.0 and SwissADME web servers as good oral bioavailability drugs.

A Study on Byproducts in the High-Pressure Melamine Production Process.

The industrial production of melamine is carried out by the thermal decomposition of urea in two technological processes, using high or low pressure. The reaction may be accompanied by the formation of undesirable byproducts, oxoaminotriazines, and so-called polycondensates, mainly melam, melem, and melon, as well as their hydrates and adducts. Their presence leads to the deterioration of the quality of the final product and may lead to the release of troublesome deposits inside the apparatus of the product's separation node. With the limited possibility of controlling the crystallization of the byproducts of the process, improving the technological process requires the precise determination of the composition of the separated insoluble reaction byproducts, which is the main objective of this work. This work presents the results of qualitative and quantitative analyses of the composition of deposits sampled in the technological process of melamine production. The full characterization of the deposits was performed using inductively coupled plasma optical emission spectroscopy (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS) techniques. The elemental analysis (EA) of carbon, hydrogen, and nitrogen allowed us to obtain characteristic C/H, C/N, and H/N ratios. X-ray diffraction (XRD) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy were also performed to confirm the obtained data. In addition, the morphology of the solid byproducts of the reaction was investigated, and the characteristics of the structures were determined using a scanning electron microscope. The elemental composition was investigated using scanning electron microscopy and the energy-dispersive X-ray spectroscopy (SEM-EDS) technique. The key finding of this research is that about 95% of the deposits are a mixture of melem and melem hydrate. The soluble part of the deposits contains melamine, urea, and oxyaminotriazines, as well as trace inorganic impurities.

Material and C/N flow analyses of alternative sludge pretreatment technologies for recovering carbon sources for denitrification

Sewage sludge can serve as a carbon source for denitrification after pretreatment and hydrolysis. However, existing technologies have various technical routes and performances for carbon recovery and nitrogen release. To evaluate the abilities of different technologies to recover carbon sources, material and elemental flow analyses were performed by parameterising and balancing the sludge compositions and conversion coefficients based on 139 datasets. Technological routes with alkali/thermal and alkali/H2O2/microwave treatments statistically achieved the highest yields of volatile soluble solids, and those with thermal and mechanical treatments dissolved the most nitrogen during pretreatment. The technological route with alkali/thermal treatment achieved the highest effective carbon source of 191 g/kg of initial total solid on average when the potential carbon consumption by the yielded soluble total nitrogen and phosphorus was subtracted. This study provides important statistical evidence for the development and comparison of alternative technologies for recovering carbon sources from sludge for denitrification.

Upgrading of kraft lignin with phosphoric acid purification: A promising route for the synthesis of renewable epoxy resins

Obtaining bioproducts of industrial interest from kraft lignin not only adds value to this residual biomass while reducing environmental impact, but also fosters the circular economy and promotes sustainable development. However, its use without the removal of ash, metals, sulfur, and nitrogen implies a reduction in the final product properties, limiting its applications. This study aims to present a simple and efficient route for the production of purified kraft lignin (LKP) with low ash 0.51% and total sulfur 0.74% content. It is produced from impure kraft lignin (LKI), with high ash 9.74% and total sulfur 1.39% content which was treated with hot H3PO4/H2O solution (dilute acid purification), aiming at the synthesis of lignin-based epoxy resins. Elemental Analysis of carbon (C), hydrogen (H), and nitrogen (N) (wt%); ash (wt%); total sulfur (wt%); moisture contents (wt%); X-ray Fluorescence; X-ray Diffraction; Infrared Spectroscopy; Thermogravimetric Analysis; and Differential Scanning Calorimetry showed that LKP improved its structural, functional; and chemical properties, particularly thermal properties: 17% increase initial decomposition temperature (Tonset), 18% decrease final decomposition temperature (Tendset), 14% increase maximum decomposition temperature (Tdmax.), 35% increase carbonaceous residue (CR) and 8% increase in the value of glass transition temperature (Tg). The limiting oxygen index (LOI) calculated for this sample was around 34%, thus configuring a “self-extinguishing” material. Moreover, its high phenolic and aliphatic hydroxyl content 8.02 mmol L−1, high aromaticity (H/C = 1.11), high weight average molar mass (Mw̅≅1900g mol−1), and ash and total sulfur low contents justify its use in the synthesis of lignin-based epoxy resins. A sample of LKP was tested in a classic epoxidation reaction to obtain the prepolymer denominated of lignin-based epoxy resin (E-LKP), whose epoxy equivalent weight (EEW) was around 3500 g mol−1, which is similar to that of the high molar mass epoxy resin, D.E.R. 668-20 2000, commercialized by Dow Chemical Company®. E-LKP was polymerized with a conventional curing agent (polyetheramine) to produce the cured lignin-based epoxy resin (R-ELKP) with good physical-chemical properties. The high glass transition temperature (Tg2 = 133 ºC), a good limiting oxygen index (LOI = 27%), and excellent aesthetic characteristics (homogeneity and high brightness) stand out. These promising results suggest that it is possible to develop cured lignin-based epoxy resin with properties comparable to cured petroleum-based epoxy resin. The use of purified kraft lignin to obtain materials (prepolymers and polymers epoxy, among others) will also favor the environment, developing greener and renewable products.

Effect of storage age and containers on the physicochemical degradation of guggul oleo-resin

Guggul is a gum oleo-resin, tapped from a data deficient plant- Commiphora wightii (Arnott.) Bhandari in India. It is extensively used in ayurvedic drugs and formulations since ages. Natural plant-based products; especially aromatic ones like guggul gum oleo-resin deteriorates, qualitatively during its storage and transits before reaching the industry for its value addition. This economical and ecological loss can be avoided if it is stored in proper containers. Physico-chemical degradation of guggul samples stored were analysed by scanned electron microscopy, fourier transformed infra red, thermogravimatric, Powdered X-ray diffraction and elemental analysis for carbon, hydrogen, nitrogen and sulphur. Physico-chemical degradation of guggul oleo-resin occurs with the age of storage and the type of storage containers used. Among the four storage containers (earthen pot, plastic jar, polythene bag, jute bag) evaluated, earthen pot was found to be the best in checking the qualitative loss of guggul even upto 24 months. The qualitative information generated in the study on guggul storage may be useful to the drug industry and guggul traders. It may encourage them practice storing guggul in earthen pots against current practice of using jute bags and polythene bags, to store it.

Fabrication and application of molecularly imprinted polymer doped carbon dots coated silica stationary phase

Facing the difficulties in chromatographic separation of polar compounds, this investigation devotes to developing novel stationary phase. Molecularly imprinted polymers (MIPs) have aroused wide attention, owing to their outstanding selectivity, high stability, and low cost. In this work, a novel stationary phase based on carbon dots (CDs), MIP layer, and silica beads was synthesized to exploit high selectivity of MIPs, excellent physicochemical property of CDs, and outstanding chromatographic performances of silica microspheres simultaneously. The MIP doped CDs coated silica (MIP-CDs/SiO2) stationary phase was systematically characterized by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area measurement, and carbon elemental analysis. Furthermore, the chromatographic performance of the MIP-CDs/SiO2 column was thoroughly assessed by using a wide variety of compounds (including nucleosides, sulfonamides, benzoic acids, and some other antibiotics). Meanwhile, the separation efficiency of the MIP-CDs/SiO2 stationary phase was superior to other kinds of stationary phases (e.g. nonimprinted NIP-CDs/SiO2, MIP/SiO2, and C18–SiO2). The results demonstrated that MIP-CDs/SiO2 column exhibited best performance in terms of chromatographic separation. For all tested compounds, the resolution value was not less than 1.60, and the column efficiency of MIP-CDs/SiO2 for thymidine was 22,740 plates/m. The results further indicate that the MIP-CDs/SiO2 column can combine the good properties of MIP, CDs, with those of silica microbeads. Therefore, the developed MIP-CDs/SiO2 stationary phase can be applied in the separation science and chromatography-based techniques.

POLYMETHYNE DYES WITH THIAZOLO (3,2-a)PYRIMIDINE AND PYRIMIDO(2,1-b)BENZTHIAZOLE SALTS WITH A TRIFLUOROMETHYL GROUP IN THE PYRIMIDINE CYCLE.

There are synthesized various types of polymethine dyes from trifluoromethylthiazo­lo(3,2-a)pyrimidinium and trifluoromethyl­pyrimido(2,1-b)benzthiazolium perchlorates various types of polymethine dyes were obtained – styryls, monomethinecyanines, symmetrical and asymmetrical carbocyanines, merocyanines. The absorption maxima and their intensities are determined for each dye, absorption characteristics curves and elemental analysis data for Carbon, Hydrogen and Sulfur are provided. As a result of the dyes absorption maxima analysis containing a tri­-fluoromethyl group in the pyrimidine ring and synthesized in this reaserch with the absorption maxima of dyes without a trifluoromethyl group in the pyrimidine ring, the bathochromic effect of the trifluoromethyl group on the dyes absorption maxima was established. The phenyl in the fifth position of the thiazole ring causes a bathochromic shift of the dye absorption maximum. There are characteristics of the absorption curve. The α- and γ-deriva­tives of monocyanines have a significant difference. The curve is flat with one absorption maximum for α-derivatives.The curve is narrower and contains two absorption maxima for γ-derivatives. The absorption curves of merocyanines also contain two maxima. The results of elemental analysis for Carbon, Hyd­rogen and Sulfur are presented. The resulting polymethine dyes are easily synthesized from thiazolo(3,2-a)pyrimidinium and pyramido­(2,3-b)benzthiazole in an acetic anhydride me­dium with product output at least 41%. The styrene product output are 53–93%. Synthesized dyes are crystallized from acetic anhydride. Symmetrical carbocyanines are crystallized from dimethylformamide.

Quantifying organic carbon in particulate and mineral-associated fractions of calcareous soils – A method comparison

Accurate quantification of soil organic carbon (OC) pools is essential to study the dynamics of OC in soils. Therefore, organic matter is often separated into physical fractions with distinct turnover times, e.g. particulate (POM) and mineral-associated organic matter (MAOM), after which their OC content is measured. Calcareous soils are under-represented in such fractionation studies, because the required analytical differentiation between OC and inorganic carbon (IC) is not straightforward and implies more processing time, sample mass and equipment. Here, we review the performance of four methods to quantify OC in POM and MAOM fractions of soils containing 3–16 g IC kg−1 and 10–25 g OC kg−1 (n = 16). We assessed the similarity and consistency of the data obtained with the different methods. Furthermore, we checked how their ability to distinguish OC from IC was influenced by the fractionation and in particular by the dispersion with sodium hexametaphosphate (SHMP). The four methods were: 1) Elemental carbon analysis after removal of IC by acid fumigation (OCfum); 2) Elemental carbon analysis after removal of IC with aqueous acid (OCaq); 3) Elemental carbon as determined by Rock-Eval 6 thermal analysis (OCRE6); and 4) Elemental carbon analysis after removal of OC by loss on ignition and subsequent quantification of OC by difference between total carbon and IC (OCLOI). We found that the OCfum, OCaq, and OCLOI methods produced similar OC contents for bulk soils, whereas OCRE6 results were slightly but significantly lower. Total recovered OCRE6 contents of the summed POM and MAOM fractions were similar to the bulk soil OCRE6 contents. In contrast, the recovered OCfum, OCaq and OCLOI contents were slightly higher than respective bulk soil OC contents (108–112%), especially in soils with high IC/OC ratios. We show that this was not caused by operational artefacts or chemical changes that occurred during OC fractionation, but rather likely indicated error propagation. We conclude that all 4 methods can reliably quantify OC in POM and MAOM fractions in calcareous soils and that the optimal choice depends on the required accuracy of the results and the available sample mass, lab equipment and processing time. Based on our findings and practical considerations, we provide guidance for the selection of the most optimal OC quantification method to study OC dynamics in calcareous soils.

Design and Synthesis of Novel Phthalazine Scaffolds Linked to 1,3,4–oxadiazolyl–1,2,3–triazoles as Potent Anticancer Agents: A Computational Docking Analysis

Background and objective: A study on the chemical and biological properties of molecules simultaneously comprising various heterocycles, such as fused 1,3,4–oxadiazole and 1,2,3–triazoles, has been conducted as part of our ongoing research in the field of medicinal and organic chemistry. In the present study, novel 1,3,4-oxadiazoles and 1,2,3-triazoles incorporating a phthalazine ring have been synthesized and evaluated for their anticancer activity and docking analysis. Methods: In this study, we performed ligand–based pharmacophore modeling as a promising design strategy of substituted phthalazin–1(2H)–one–1,3,4–oxadiazole acetamides (4); 1,2,3–triazole–1,3,4–oxadiazolyl)phthalazin-1(2H)-one (5) were synthesized from key intermediate 2-((5-mercapto-1,3,4-oxadiazol-2-yl)methyl)-4-methylphthalazin-1(2H)-one 2. The prepared compounds were characterized by proton and carbon nuclear magnetic resonance spectroscopy, infrared, elemental analysis, and mass spectroscopy. Synthesized scaffolds were screened for their anticancer activity against three cell lines, MCF-7, T-47D, and MDA-MB-231, by MTT assay. The prepared ligands were docked by using the input protocols, like RCSB, AutoDock 4.2, ACD ChemSketch, Open Babel, and SwissADME. Results: The final compound 5f exhibited excellent activity (IC50 = 10.21 ± 2.2, 7.53 ± 0.1 µM) against T-47D and MCF-7 cancer cell lines, respectively, and compounds 4b and 5b showed the highest % growth of inhibition (61.25 ± 0.52, 62.48 ± 0.20 µg/mL) against T-47D and MCF-7 cell lines, which has been found to be equivalent to that reported by the standard cisplatin. The prepared ligand 5f exhibited greatest bonding with amino acids AlaX:191, MetX:193, ValX:196, ThrX:140, PheX:192, TyrX:155, AsnX:90, LysX:159, LeuX:95, and IleX:14, with a docking score of –11.53 Kcal/mol, respectively. These compounds were further evaluated for their ADMET and physicochemical properties by using SwissADME. Conclusion: Phthalazine with 1,3,4–oxadiazole substituents and 1,2,3–triazoles containing 1,3,4–oxadiazole ring displayed excellent anticancer activity; some interesting relationship has also been evidenced between the synthesised structures and their antimicrobial activity and docking studies. In light of all the above findings, it can be concluded that these molecules may serve as lead molecules for further synthetic and biological evaluation.

SYNTHESIS, CHARACTERIZATION OF COPPER(II) COMPLEX WITH TETRADENTATE N2O2 AND POTENTIAL CONTRIBUTION AS PROMISING ANTIBACTERIAL STUDIES

A square planar Schiff base complex, Cu(H2L) namely N,N’-bis(4-methyl-α-salicylidene)propane-1,3-diaminecopper(II) through the condensation reaction of ligand with copper(II) acetate in the molar ratio of 1:1 in acetonitrile solvent was successfully synthesized. The obtained complex was characterized using, elemental analysis of carbon, hydrogen and nitrogen (CHN), Fourier Transform Infrared spectroscopy (FTIR) and electronic spectra of ultraviolet-visible (UV-vis) spectroscopy. FTIR confirmed the coordinates the metal ion to form mononuclear complex via tetradentate (ONNO) atoms of the phenolic group and azomethine group, respectively. The antibacterial studies of H2L and its Cu(H2L) were determined by screening the compounds against selected various Gram (+) and Gram (-) bacterial strains such as Staphylococcus epidermidis, Bacillus subtilis, Staphylococcus aureus, Vibrio cholera, Enterobacter cloacae and Escherichia coli. Indeed, preliminary results exhibited Cu(H2L) more active than the free ligand and displayed promising antibacterial activity, while no effect has been observed on strains for H2L.