Chemical composition and antimicrobial activity of the essential oil of Anthemis altissima L. var. altissima

The essential oil obtained from the flowering parts of Anthemis altissima L. var. altissima was analysed by gas chromatography and gas chromatography mass spectroscopy. In this study, 34 compounds representing 98.76% of the essential oil were identified. The main components were α-terpineol (26.42%), β-pinene (9.23%), cis-chrysanthenyl acetate (6.30%), globulol (5.36%), n-tricosane (4.41%), terpinen-4-ol (4.08%) and 1,8 cineole (3.84%). Antibacterial activities of the essential oil and its two major components (α-terpineol and β-pinene) were determined using microdilution method against both Gram-positive (Staphylococcus aureus, Bacillus subtilis, Staphylococcus epidermidis) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae) bacteria. The essential oil showed a broad-spectrum antibacterial activity (MICs ranged from 3.13 to 6.25?μL?mL(-1)). It was found that α-terpineol with minimum inhibitory concentration (MIC) values of the range 0.87-1.56?μL?mL(-1) was a more potent antibacterial agent than β-pinene with MIC values of the range 1.56-6.25?μL?mL(-1). All of them, the essential oil, β-pinene and α-terpineol, were more effective against Gram-positive bacteria than Gram-negative ones.     

Optical band gap and conductivity measurements of polypyrrole-chitosan composite thin films

Electrical conductivity and optical properties of polypyrrole-chitosan（PPy-CHI） conducting polymer composites have been investigated to determine the optical transition characteristics and energy band gap of composite films.The two electrode method and I-V characteristic technique were used to measure the conductivity of the PPy-CHI thin films,and the optical band gap was obtained from their ultraviolet absorption edges.Depending upon experimental parameter,the optical band gap（E_g） was found within 1.30-2.32 eV as estimated from optical absorption data.The band gap of the composite films decreased as the CHI content increased.The room temperature electrical conductivity of PPy-CHI thin films was found in the range of 5.84×10^-7-15.25×10^-7 S·cm^-1 depending on the chitosan content.The thermogravimetry analysis（TGA） showed that the CHI can improve the thermal stability of PPy-CHI composite films.     

Developments in hollow fiber based liquid-phase microextraction: principles and applications

Hollow fiber liquid-phase microextraction (HF-LPME) offers an efficient alternative to classical techniques for sample preparation and preconcentration. Features include high selectivity, good enrichment factors, and improved possibilities for automation. HP-LPME relies on the extraction of target analytes from aqueous samples into a supported liquid membrane (SLM) sustained in the pores of the wall of a porous hollow fiber, and then into an acceptor phase (that can be aqueous or organic) in the lumen of the hollow fiber. After extraction, the acceptor solution is directly subjected to a chemical analysis. HP-LPME can be performed in either the 2- or 3-phases mode. In the 2-phase mode, the organic solvent is present both in the porous wall and inside the lumen of the hollow fiber. In the 3-phase mode, the acceptor phase can be aqueous and this results in a conventional 3-phase system compatible with HPLC or capillary electrophoresis. Alternatively, the acceptor solution is organic and this represents a 3-phase extraction system with two immiscible organic solvents that is compatible with all common analytical instruments. In HP-LPME methods based on the use of SLMs, the mass transfer occurs by passive diffusion, and high extraction yields as well as efficient extraction kinetics are obtained by applying a pH gradient. In addition, active transport can be performed by using carrier or applying an electrical potential across the SLM. Due to high analyte preconcentration, excellent sample clean-up, and low consumption of organic solvent, HF-LPME has a large application potential in areas such as drug analysis and environmental monitoring. This review focuses on the fundamentals of extraction principles, technical implementations, and future trends in HF-LPME.

Synthesis and Characterization of Single-Phase Cubic ZrO2 Spherical Nanocrystals by Decomposition Route

A simple thermal decomposition route has been developed to prepare single-phase cubic ZrO₂ nanospheres by [Zr(sal)₃(H₂O)₂](NO₃) as the new precursor. The ZrO₂ nanocrystals have been prepared by bis-aqua, tris-salicylaldehydato zirconium(IV) nitrate; [Zr(sal)₃(H₂O)₂](NO₃), as precursor in oleylamine (C₁₈H₃₇N) and triphenylphosphine (C₁₈H₁₅P). To control the particle size, combination of C₁₈H₃₇N and C₁₈H₁₅P were applied as surfactants. The C₁₈H₃₇N and C₁₈H₁₅P play an important role in preventing aggregation of ZrO₂ nanocrystals. The products were characterized by X-ray diffraction, transmission electron microscopy, photoluminescence spectroscopy, and Fourier transform infrared (FT-IR) spectroscopy to depict the phase and morphology. The FT-IR spectrum showed the purity of obtained ZrO₂ nanocrystals with cubic phase.     

Solar UV irradiation and dermal photoaging.

The skin is increasingly exposed to ambient UV-irradiation thus increasing risks for photooxidative damage with long-term detrimental effects like photoaging, characterized by wrinkles, loss of skin tone and resilience. Photoaged skin displays alterations in the cellular component and extracellular matrix with accumulation of disorganized elastin and its microfibrillar component fibrillin in the deep dermis and a severe loss of interstitial collagens, the major structural proteins of the dermal connective tissue. The unifying pathogenic agents for these changes are UV-generated reactive oxygen species (ROS) which deplete and damage non-enzymatic and enzymatic antioxidant defense systems of the skin. As well as causing permanent genetic changes, ROS activate cytoplasmic signal transduction pathways in resident fibroblasts that are related to growth, differentiation, senescence and connective tissue degradation. This review focuses on the role of UV-induced ROS in the photodamage of the skin resulting in clinical and biochemical characteristics of photoaging. In addition, the relationship of photoaging to intrinsic aging of the skin will be briefly discussed. A decrease in the overall ROS load by efficient sunscreens or other protective agents may represent promising strategies to prevent or at least minimize ROS-induced photoaging.     

Cotton fabric incorporated with β-cyclodextrin/ketoconazole/Ag NPs generating outstanding antifungal and antibacterial performances

Cellulose - The influence of ketoconazole and β-CD/ketoconazole on cotton fabric as fungal skincare was previously reported however the impact of nanosilver on the antifungal and antibacterial...     

A 13C-NMR study of bicycloconjugation among benzannulated 9-heterobicyclo[4.2.1]Nona-2,4,7-trienes

The question of heterobicycloconjugation among certain newly prepared symmetrically benzannulated 9-heterobicyclo[4.2.1]nona-2.4.7-trienes (3) was examined by 13C-NMR with results entirely supportive of the simple theoretical operatives developed earlier.     

Thiozonation and thiozonolysis of triatomic sulfur (S<Subscript>3</Subscript>) on the C<Subscript>70</Subscript> fullerene: a DFT study

Density functional theory calculations have been carried out to investigate the [2?+?x] x?=?1, 2, and 3 cycloaddition reactions (paths A, B, and C) of triatomic sulfur (S₃) with the C₇₀ fullerene in terms of geometry, energies, and electronic structures. The thiozonation (S₃) on the hexagon–hexagon and hexagon–pentagon bonds of the C₇₀ fullerene through 1,3-dipolar reaction, i.e., [2?+?3] cycloaddition, is generally exothermic, while through the chelotrope additions, i.e., [2?+?1] cycloaddition, are endothermic. The results indicate that the 1,3-dipolar cycloaddition is the most preferable path. Having more negative values of reaction energies E_r together with the lower barrier heights, thiozonation of the hexagon–hexagon bonds is thermodynamically and kinetically more favorable than hexagon–pentagon ones. Moreover, the addition of thiozone to the hexagon–hexagon bonds near the pole area of the C₇₀ leads to more negative reaction energies. Therefore, it is established that the arrangement and position of C=C bonds play an important role in the thiozonation of C₇₀ fullerene. Thiozonolysis of triatomic sulfur (S₃) indicates that S–S bond cleavage has not occurred, instead a sulfur bridge over a C–C bond or a four-membered ring of 1,2-dithietane-1-sulfide is preferred to be formed.     

A metal organic framework prepared from benzene-1,3,5-tricarboxylic acid and copper(II), and functionalized with various polysulfides as a sorbent for selective sorption of trace amounts of heavy metal ions

Novel composites were obtained via direct assembly of polysulfides (S_x^2?, X?=?3, 4, 6) on the surface of a metal organic framework (MOF; type benzene-1,3,5-tricarboxylic/Cu(II). They are referred to as S_x-MOFs and were used for highly selective and efficient extraction of ultra-trace amounts of heavy metal ions from aqueous solutions. The structure of the S_x-MOFs was characterized by Raman spectroscopy, FT-IR, X-ray diffraction, and scanning electron microscopy. The Raman spectra of S_x-MOF is similar to the bare MOF and shows the MOFs structure to be well retained after S_x functionalization. The selective interaction of S_x with soft metal ions and the high surface area of MOFs resulted in excellent affinity and selectivity for ions such as Hg(II). The S_x-MOFs of type S₄-MOF had the highest distribution coefficient K_d value (~10⁷) and best extraction recovery (~100%) for Hg(II). The S₄-MOF also has high selectivity in the following order: Hg(II) >?>?Pb(II)?>?Zn(II)?>?Ni(II)?>?Co(II). The binding process of the metals occurs via M–S bonding. The ions were quantified by inductively coupled plasma optical emission spectrometry (ICP-OES). The detection limit for Hg(II) is 0.13 μg L^?1. The S₄-MOF was applied to the extraction of trace metal ions from natural and contaminated waters and data were compared with other sorbets. The results revealed that S₄-MOF is an excellent adsorbent for sorption of heavy metal ions even in the presence of the relatively high concentration of other ions.

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Graphical abstract A composite was synthesized via direct assembly of polysulfides (S_x^2?, X?=?3, 4, 6) on surface of the metal organic framework (S_x-MOF) and was used for selective and efficient extraction of ultra-trace amounts of heavy metal ions from aqueous solutions.