Influence of boron doping on characteristics of glucose based hydrothermal carbons

In this study, the influence of boron doping on structural and surface properties of carbon material synthesized by hydrothermal method was investigated, and the obtained results were compared with the previously published influence that boron has on characteristics of carbonized boron-doped hydrothermal carbons (CHTCB). Hydrothermal carbons doped with boron (HTCB), were obtained by hydrothermal synthesis of glucose solution with the different nominal concentrations of boric acid. It was found that glucose based hydrothermal carbon does not have developed porosity, and the presence of boron in their structure has insignificant influence on it. On the contrary, additional carbonization increases the specific surface area of the undoped sample, while the increase in boron content drastically decreases specific surface area. Boron doping leads to a decrease in the amount of surface oxygen groups, for both, hydrothermally synthesized and additionally carbonized material. Raman analysis showed that boron content does not affect the structural arrangement of HTCB samples, and Raman structural parameters show higher degree of disorder, compared to the CHTCB samples. Comparison of structural and surface characteristics of hydrothermal carbons and carbonized materials contributes to the study of the so far, insufficiently clarified influence that boron incorporation has on the material characteristics.

A study of the effects of sodium alginate and sodium carboxymethyl cellulose on the growth of the common duckweed (Lemna minor L.)

Sodium alginate (ALG) and sodium carboxymethyl cellulose (CMC) are two polysaccharides that have a wide range of applications which could lead to accidental pollution of the environment, making the assessment of their potential ecotoxicity imperative. The present study assesses the ALG and CMC effects on the growth response of the common duckweed (Lemna minor L.). The results emphasize that both polysaccharides can be classified as practically nontoxic based on their EC50 values, with ALG having a relatively higher toxicity compared to CMC. It was also observed that high doses of 1, 5 and 10 mg mL-1 of the two polysaccharides produced growth inhibitory effects against common duckweed. The toxicity of biopolymers against common duckweed, measured as EC50 values, seems to be correlated to the hydrophobicity of the monomers building the polymer. The EC50 values increase linearly with the increase of water solubility (log S) values and decrease linearly with the lipophilicity (log P) values.

Examination and optimization of lignocellulolytic activity of S. gausapatum F28 on beechwood sawdust supplemented with molasses stillage

This study provides detailed analysis of the lignocellulolytic activity of a new isolate Stereum gausapatum F28, Serbian autochthonous fungi, on beechwood sawdust supplemented with cheap waste, sugar beet molasses stillage. Advanced multiple response optimization techniques were applied to improve ligninolytic and reduce hydrolytic activity as a requirement for potential biorefinery use. The applied techniques were supposed to select cultivation conditions that would give manganese peroxidase and laccase activities above 0.84 and 0.12 U g-1 substrate, respectively, and cellulase and xylanase activities below 1.12 and 1.4 U g-1 substrate. The optimal cultivation conditions that met the set requirements included molasses stillage concentration of 10 %, substrate moisture content of 53 %, incubation temperature of 23.5?C, and pH 5.2. The research showed that the addition of molasses stillage had positive effect on the enzyme production and that the optimal stillage concentration differed depending on the enzyme type (for laccase it was <5 %, manganese peroxidase ~12 %, cellulase ~21 %, xylanase ~16 %), which should be taken into consideration when optimizing the desired process.

Spatial and temporal evaluation of physicochemical quality of drinking/using water in Kırklareli Reservoir (Turkish Thrace)

K?rklareli Reservoir locating in Meri?-Ergene River Basin is an important drinking/using a freshwater resource of K?rklareli Province. In order to ensure the sustainable use of this important reservoir, its current situation should be examined periodically and evaluated by multivariate analyses. For this reason, the water samples were taken between the dates April 2018 and February 2019 at monthly intervals from 3 different stations. The data of environmental and physicochemical variables (water temperature, dissolved oxygen, pH, salinity, conductivity, total dissolved solids, Chlorophyll-a, light permeability, fluoride, chloride, NO2-N, NO3-N, PO4, SO4, and essential/potentially toxic elements) measured and evaluated according to the classes in surface water quality control regulation of Turkey. The parameters exceeding first-class water quality values (chlorophyll-a, pH, NO2-N, chloride, selenium) were mapped in GIS using Spline integration approach. Also, Sodium Absorbtion Ratio, Kelly Index Values, and Magnesium Ratio, were calculated to evaluate the water quality for agricultural irrigation water standards. The water quality of the reservoir was evaluated by using multivariance analyses (Bray-Curtis Similarity Index, Correspondence Analyses, Pearson Correlation Index). As a result, it was emphasized that using GIS approach is a potential useful method of monitoring the sustainable water quality of K?rklareli reservoir which is determined to have an oligomesotrophic character.

Application of biosynthesized metal nanoparticles in electrochemical sensors

Recently, the development of eco-friendly, cost-effective and reliable methods for synthesis of metal nanoparticles has drawn a considerable attention. The so-called green synthesis, using mild reaction conditions and natural resources as plant extracts and microorganisms, has established as a convenient, sustainable, cheap and environmentally safe approach for synthesis of a wide range of nanomaterials. Over the past decade, biosynthesis is regarded as an important tool for reducing the harmful effects of traditional nanoparticle synthesis methods commonly used in laboratories and industry. This review emphasizes the significance of biosynthesized metal nanoparticles in the field of electrochemical sensing. There is increasing evidence that green synthesis of nanoparticles provides a new direction in designing of cost-effective, highly sensitive and selective electrode-catalysts applicable in food, clinical and environmental analysis. The article is based on 157 references and provided a detailed overview on the main approaches for green synthesis of metal nanoparticles and their applications in designing of electrochemical sensor devices. Important operational characteristics including sensitivity, dynamic range, limit of detection, as well as data on stability and reproducibility of sensors have also been covered. Keywords: biosynthesis; green synthesis; nanomaterials; nanotechnology; modified electrodes

Reactions of copper(II) bromide with 2,6-diacetylpyridine bis(phenyl-hydrazone) (L)-molecular and crystal structure of L and its mixed-valence complex [cuiil2][cui2br4]

Utilizing X-ray crystallography the crystal and molecular structures of 2,6-diacetylpyridine bis(phenylhydrazone) (L) were determined. Energetics of the intermolecular interactions in the crystal structure was assessed with computational methods, revealing that dispersion interactions are dominant. The basic structural unit of the crystal packing is revealed to be the herring-bone type arrangement of L molecules. Assignation of the IR spectrum of L with the aid of DFT calculations was performed. Furthermore, new reactions of L with CuBr2 in different solvents are described, which led to the synthesis of the mixed Cu(II)-Cu(I) complex of the formula [CuIIL2][CuI2Br4] (1), and its structural characterization. In the complex cation, two molecules of tridentate N3 ligand are meridionally arranged in a very distorted octahedral environment of a Cu(II) ion. In [Cu2Br4]2-, bromide ions are arranged in a trigonal-planar geometry around each copper(I) atom. Finally, for the ligand, 1, and the previously synthesized complex [CuL2]Br2, thermal properties were examined. The thermal stability of the com-plexes is lower than that of the ligand and decreases in order: L (250?C) > > [CuL2]Br2 (221?C) > [CuIIL2][CuI2Br4] (212?C). The differences in thermal stability of the complexes are due to differences in packing efficacy of the constitutional ions.

Hydroxyapatite/nifuroxazide conjugate: Characterization, drug release and antimicrobial activity

Synthetic hydroxyapatite (Ca10(PO4)6(OH)2, HAp) is very similar to the inorganic part of the bones and teeth of mammals. It is a well-known biomaterial with good biocompatibility, osteoconductivity and bioactivity. Nifuroxazide (C12H9N3O5, NFX) is a broad-spectrum antibacterial drug and poorly soluble in water. In order to increase the solubility of NFX, nanosized HAp powder and raw NFX drug were mixed giving, as a result, HAp/NFX conjugate. Characterization of the raw materials and the obtained conjugate confirmed the integration of NFX on the HAp surface. The in vitro study of drug release in simulated stomach acid and intestinal fluid showed a much faster release of NFX from HAp surface than those of raw drug. HAp/NFX conjugate showed an excellent inhibitory effect against Gram-positive bacterium Staphylococcus aureus, Gram-negative bacterium Escherichia coli and yeast Candida albicans, proving the nanosized HAp powder as a promising drug carrier.

Large-scale comparison between the diffraction-component precision indexes favors Cruickshank’s Rfree function

This study aims to provide a first large-scale comparison between the various diffraction-component precision index (DPI) equations, assess the applicability of the parameter, and make recommendations on DPI computation. The DPI estimates the average accuracy of atomic coordinates obtained by the structural refinement of protein diffraction data, with application in crystallography and cheminformatics. Although, Cruickshank and Blow proposed DPI equations based on R- and Rfree to calculate DPI values, these remain scarcely employed in the quality assessment of Protein Data Base (PDB) files, due to unclear data extraction protocols (to assign variables), complex equations, lack of extensive applicability studies and limited access to automated computations. In order to address these shortcomings, the entire RCSB PDB database was evaluated using Cruickshank's and Blow's R and Rfree DPI variations. Computations of 143070 X-ray structures indicate that Rfree-based DPI equations apply to 30 % more protein structures compared to R-based DPI equations, with Cruickshank Rfree-based DPI (CRF) exceeding the number of successful Blow?s Rfree-based DPI (BRF) computations. Although our results indicate that, in general, resolutions < 2 ? assure consistency among the various DPIs computations (differences <0.05 ?), we recommend the use of CRF DPI because of its wider applicability.

Two new jatrophane diterpenes from the roots of Euphorbia nicaeensis

In the previous study, fifteen jatrophane diterpenes were isolated from the Euphorbia nicaeensis latex. Fourteen of them have been shown to be potent P-glycoprotein (P-gp) inhibitor in two MDR cancer cells (NCI-H460/R and DLD1-TxR). The aim of this study was to determine whether and which jatrophane diterpenes can be isolated from the root of the plant, and then to examine their inhibition power on P-glycoprotein of selected cancer cell lines (NCI-H460, DLD1, U87, NCI-H460/R, DLD1-TxR, and U87-TxR). Two previously undescribed jatrophane diterpenes were isolated from the root of E. nicaeensis collected in Deliblato Sand (Serbia). The structures of the isolated compounds were determined using 1D and 2D NMR, as well as HRESIMS data. The results obtained by MTT assay showed different antitumor potential of these two jatrophanes. Compound 1 inhibited cell growth of non-small cell lung carcinoma cell lines NCI-H460 and NCI-H460/R, as well as glioblastoma cell lines U87 and U87-TxR, while jatrophane 2 was almost completely inactive in the suppression of cancer cell growth in a given range of concentrations. The obtained results also showed that isolated compounds have an inhibitory effect on P-glycoprotein, as well as that their inhibitory potential is similar.

Chemical composition and biological properties of Pelargonium graveolens, Leptospermum petersonii and Cymbopogon martinii var. motia essential oils and of Rosa centifolia absolute

Chemical composition of the essential oils (EO) of Pelargonium graveolens, Leptospermum petersonii and Cymbopogon martinii var. motia, and the absolute of Rosa centifolia and their bioactivity were examined. Major compounds in P. graveolens EO were monoterpene alcohols citronellol, geraniol and linalool; in L. petersonii EO monoterpene aldehydes geranial, neral and citronellal; in C. martiniii var. motia EO monoterpene alcohol geraniol and ester geranyl acetate, while in absolute of R. centifolia aromatic alcohol 2-phenyl-ethanol. The EO of L. petersonii showed the strongest antibacterial while the EO of C. martinii var. motia the strongest antifungal potential. The best biofilm inhibition capacity was observed with R. centifolia absolute. The results of Scanning Electron Microscopy (SEM) analysis indicated that the EOs of L. petersonii and P. graveolens changed the number and morphology of C. albicans cells. The L. petersonii EO was the most potent toward tumour cells and exhibited the best biological activity. This is first comparative report summarizing efficacy of studied aromatic samples against pathogenic microbes, providing deeper insight into the modes of antimicrobial action, and at the same time describing their cytotoxicity against cell lines.