Solid-phase microextraction-gas chromatography-time-of-flight mass spectrometry utilized for the evaluation of the new-generation super elastic fiber assemblies

The aim of this study was to evaluate the performance characteristics of the recently developed super elastic solid-phase microextraction (SPME) fibers. The fiber needle, plunger and fiber core are manufactured with a special type of flexible alloy that exhibits excellent shape memory and tensile strength. This material makes the assemblies more robust, permitting several hundreds of analyses in a sequence, which is one of the ways to improve the robustness and sample throughput of automated SPME methods. The design and size of the needle utilized in the new fiber assemblies is discussed here, as well as the use of a septum-free injector replacement and a low-volume direct injection glass liner placed in the GC inlet. Deionized water and pump oil samples spiked with target volatile compounds (McReynold's probes and toluene) were used for the purposes of the presented study. A fully automated SPME sample preparation technique was combined with the GC-TOFMS system for the chromatographic separation and identification/quantification of the target analytes.     

Rapid headspace solid-phase microextraction-gas chromatographic-time-of-flight mass spectrometric method for qualitative profiling of ice wine volatile fraction. II: Classification of Canadian and Czech ice wines using statistical evaluation of the data

The previously developed and optimized headspace solid-phase microextraction (HS-SPME)-GC-time-of-flight (TOF) MS analytical method for the determination of compounds with a wide range of polarities and volatilities was successfully used in this study to characterize and classify a large set of ice wines according to their origin, grape variety and oak or stainless steel fermentation/ageing conditions, based on a statistical evaluation (principal component analysis (PCA)) of the measured data. More than 130 ice wine samples collected directly from Canadian and Czech wine producers were analyzed in this study. The SPME step was beneficially carried out utilizing the new-generation super elastic divinylbenzene/Carboxen/polydimethylsiloxane (DVB/CAR/PDMS) 50 microm/30 microm fiber assembly. One fiber was used for the whole sequence of ice wine samples, control and blank experiments, which consisted of more than 600 individual extraction/injection cycles. Utilizing the high-speed TOF analyzer, full spectral information within the range of 35-450 u was collected for the entire GC run (as short as 4.5 min) without compromising in the detection sensitivity, as compared to other scanning mass analyzers operated in selected ion monitoring or MS(n) mode to achieve similar sensitivity. The identification of analytes was performed by a combination of the linear temperature-programmed retention index (LTPRI) approach with the comparison of the obtained spectra with three libraries included in the ChromaTOF software. A total of 201 peaks were tentatively assigned as ice wine aroma components and 58 of those compounds were evaluated in all of the examined samples.     

Bioprospecting of Coralline Red Alga Amphiroa rigida J.V. Lamouroux: Volatiles,Fatty Acids and Pigments

Due to the lack of phytochemical composition data, the major goals of the present study on Amphiroa rigida J.V. Lamouroux were to: (a) investigate and compare volatilome profiles of fresh and air-dried samples obtained by headspace solid-phase microextraction (HS-SPME) and hydrodistillation (HD) followed by gas chromatography and mass spectrometry (GC/MS) analysis; (b) determine fatty acids profile by gas chromatography with flame ionization detector (GC-FID); (c) obtain the pigment profiles of semipurified extracts by high performance liquid chromatography (HPLC) and (d) evaluate the antioxidant and antimicrobial activities of its less polar fractions. The comparison of headspace of fresh (FrAr) and air-dried (DrAr) samples revealed many similarities regarding the presence and abundance of the major (heptadecane and pentadecane) and minor compounds. The hydrodistillate (HD) of DrAr profile was quite different in comparison to HD-FrAr. The predominant compound in HD-FrAr was (E)-phytol. In HD-DrAr, its percentage was approximately one-half reduced, but the abundance of its degradation product phytone and of unsaturated and oxygenated compounds increased indicating more intense fatty acid decomposition and oxidation during drying. The fatty acid determination revealed that the most dominant was palmitic acid (42.86%) followed by eicosapentaenoic acid (19.14%) and stearic acid (11.65%). Among the pigments, A. rigida contained fucoxanthin (0.63 mg g⁻¹ of dry fraction), lutein (5.83 mg g⁻¹), β-carotene (6.18 mg g⁻¹) and chlorophyll a (13.65 mg g⁻¹). The analyzed less polar fractions of A. rigida exhibited antioxidant scavenging activity with diammonium salt of 2,2′-azino-bis (3-ethylbenzthiazolin-6-yl) sulfonic acid (ABTS) assay up to 3.87 mg g⁻¹ trolox equivalents (TE), and with the oxygen radical absorbance capacity (ORAC) assay up to 825.63 μmol g⁻¹ TE (with carotenoids as the major contributors).     

Photocatalytic degradation of metoprolol in water suspension of TiO<Subscript>2</Subscript> nanopowders prepared using sol–gel route

Nanocrystalline titanium dioxide (TiO₂) powders have been synthesized by sol–gel method using titanium tetrachloride (TiCl₄) or tetrabutyl titanate (Ti(OC₄H₉)₄ as precursors, different alcohols and calcination temperatures in the range from 400 to 650 °C. The photocatalytic activity of as-prepared powders has been tested for the degradation of metoprolol tartrate salt, a selective β-blocker used to treat a variety of cardiovascular diseases, and compared to photocatalytic activity obtained from Degussa P25. Nanosized TiO₂ powders prepared from TiCl₄ and amyl-alcohol, calcined at 550 °C, displayed an activity comparable to Degussa P25, whereas the sample from the same series, calcined at 650 °C, showed higher photocatalytic activity in the whole range of the catalyst loading. Structural, morphological and surface properties of synthesized TiO₂ nanopowders have been investigated by XRD, SEM, EDS and BET measurements, as well as FTIR and Raman spectroscopy, in order to find out the material properties which enable rapid an efficient decomposition of metoprolol under UV radiation.     

The large scale conformational change of the human DPP III-substrate prefers the "closed" form

Human dipeptidyl peptidase III (DPP III) is a two domain metallo-peptidase from the M49 family. The wide interdomain cleft and broad substrate specificity suggest that this enzyme could experience significant conformational change. Long (>100 ns) molecular dynamics (MD) simulations of DPP III revealed large range conformational changes of the protein, suggesting the pre-existing equilibrium model for a substrate binding. The binding free energy calculations revealed tighter binding of the preferred synthetic substrate Arg-Arg-2-naphtylamide to the "closed" than to the "open" DPP III conformation. Our assumption that Asp372 plays a crucial role in the large scale interdomain closure was proved by the MD simulations of the Asp372Ala variant. During the same simulation time, the variant remained more "open" than the wild type protein. Apparently, Ala was not as efficient as Asp in establishing the interdomain interactions. According to the MM-PBSA calculations, the electrostatic component of the free energy of solvation turned out to be higher for the "closed" protein than for its less compact form. However, the gain in entropy due to water released from the interdomain cleft nicely balanced this negative effect.     

RHF conformational analysis of the auxin phytohormones n-ethyl–indole-3-acetic acid (n=4, 5, 6)

RHF/6-31G* investigations of 4-, 5-, and 6-ethyl(Et)–indole-3-acetic acid (IAA) yielded 11 symmetry-unique local minima with syn-periplanar orientation of the  COOH group for each of these compounds. The global minima are of C₁ symmetry in all cases. Comparison with earlier results shows that ethylation or chlorination in position 5 or 6 introduces only minor changes on the orientation of the acetic acid side group, with no effect on the reaction paths related to this group. For 4-Et–IAA, the deviations from unsubstituted IAA are larger but preserve the pattern of reaction paths that is present in unsubstituted IAA, which is in contrast to 4-Cl–IAA, where local minima and reaction paths are completely different. © 1998 John Wiley & Sons, Inc. Int J Quant Chem 70: 1169–1175, 1998     

Identification of SARS-CoV-2 Papain-like Protease (PLpro) Inhibitors Using Combined Computational Approach**

In the current pandemic, finding an effective drug to prevent or treat the infection is the highest priority. A rapid and safe approach to counteract COVID-19 is in silico drug repurposing. The SARS-CoV-2 PLpro promotes viral replication and modulates the host immune system, resulting in inhibition of the host antiviral innate immune response, and therefore is an attractive drug target. In this study, we used a combined in silico virtual screening for candidates for SARS-CoV-2 PLpro protease inhibitors. We used the Informational spectrum method applied for Small Molecules for searching the Drugbank database followed by molecular docking. After in silico screening of drug space, we identified 44 drugs as potential SARS-CoV-2 PLpro inhibitors that we propose for further experimental testing.     

Antibacterial Properties of Non-Modified Wool,Determined and Discussed in Relation to ISO 20645:2004 Standard

Wool is considered to possibly exhibit antibacterial properties due to the ability of wool clothing to reduce the build-up of odor, which arises from the microbial activity of skin microbiota. Indeed, when tested with a widely used agar diffusion plate test method, even wool or other textiles not treated with any antimicrobial agent can be interpreted to show certain antibacterial effects due to the lack of growth under the specimen, as instructed in ISO 20645:2004 standard. Therefore, we analyzed in detail what happens to bacterial cells in contact with untreated wool and cotton fabric placed on inoculated agar plates by counting viable cells attached to the specimens after 1 and 24 h of contact. All wool and several cotton samples showed no growth under the specimen. Nevertheless, it was shown without a doubt that neither textile material kills bacteria or inhibits cell multiplication. A reasonable explanation is that bacterial cells firmly attach to wool fibers forming a biofilm during multiplication. When the specimen was lifted off the nutrient agar surface, the cells in the form of biofilm remained attached to the wool fibers, removing the biomass and resulting in a clear, no growth zone underneath it. By imaging the textile specimens with X-ray microtomography, we concluded that the degree of attachment could be dependent on surface topography. The results indicate that certain textiles, in this case, wool, could exhibit antibacterial properties by removing excess bacteria that grow on the textile/skin interface when taken off the body.     

A cooperative hyper-heuristic search framework

In this paper, we aim to investigate the role of cooperation between low level heuristics within a hyper-heuristic framework. Since different low level heuristics have different strengths and weaknesses, we believe that cooperation can allow the strengths of one low level heuristic to compensate for the weaknesses of another. We propose an agent-based cooperative hyper-heuristic framework composed of a population of heuristic agents and a cooperative hyper-heuristic agent. The heuristic agents perform a local search through the same solution space starting from the same or different initial solution, and using different low level heuristics. The heuristic agents cooperate synchronously or asynchronously through the cooperative hyper-heuristic agent by exchanging the solutions of the low level heuristics. The cooperative hyper-heuristic agent makes use of a pool of the solutions of the low level heuristics for the overall selection of the low level heuristics and the exchange of solutions. Computational experiments carried out on a set of permutation flow shop benchmark instances illustrated the superior performance of the cooperative hyper-heuristic framework over sequential hyper-heuristics. Also, the comparative study of synchronous and asynchronous cooperative hyper-heuristics showed that asynchronous cooperative hyper-heuristics outperformed the synchronous ones.     

Generalized group actions in a global setting

We study generalized group actions on differentiable manifolds in the Colombeau framework, extending previous work on flows of generalized vector fields and symmetry group analysis of generalized solutions. As an application, we analyze group invariant generalized functions in this setting.