Salen impregnated silica gel as a new sorbent for on-line preconcentration of cadmium(II)

A new sorbent – salen impregnated silica gel – was prepared and characterised for application as a minicolumn packing for flow-injection on-line preconcentration of cadmium(II). The system was coupled with flame atomic absorption spectrometer (FI-FAAS). The optimal pH for Cd(II) sorption was in the range of 7.4–8.8 and nitric acid (1%, v/v) was efficient as eluent. Sorption was most effective within the sample flow rate up to 7?mL?min^?1. Sorption capacity of the sorbent found in a batch procedure was 26.3?µmol?g^?1 (2.95?mg?g^?1). Enrichment factor (EF) and limit of detection (LOD) obtained for 120-second loading time were 113 and 0.26?µg?L^?1, respectively. The sorbent stability in the working conditions was proved for at least 100 preconcentration cycles. The evaluated method was applied to Cd(II) determination in various water samples.     

Aryl Crown Ethers Based on d-Glucose Scaffold – Highly Selective Receptors of Amino Acid Ester Hydrochlorides

Amino acids are important biomolecules with a broad scope of applications in chemical and biological sciences. Their functions and properties depend on their absolute configuration. Therefore, methods for chiral recognition and separation of amino acids are highly sought after. For the purposes of diagnostic and medicinal applications chiral recognition of amino acids in water is particularly relevant. However synthetic receptors for enantioselective binding of amino acids in aqueous media are rare. Recently we reported a d -glucose-based crown ether for chiral recognition of amino acid esters in water. We achieved enantioselectivities towards amino acids with hydrophobic sidechains which were among the highest ever reported for a small molecule receptor. The binding affinities were however moderate. Herein we disclose analogs of that receptor, containing aryl functionalities in the crown ether fragment. The new receptors show considerably improved binding affinities for amino acid ester hydrochlorides in water, while retaining high enantio- or chemoselectivities.     

The Raw Milk Microbiota from Semi-Subsistence Farms Characteristics by NGS Analysis Method

The aim of this study was to analyze the microbiome of raw milk obtained from three semi-subsistence farms (A, B, and C) located in the Kuyavian-Pomeranian Voivodeship in Poland. The composition of drinking milk was assessed on the basis of 16S rRNA gene sequencing using the Ion Torrent platform. Based on the conducted research, significant changes in the composition of the milk microbiome were found depending on its place of origin. Bacteria belonging to the Bacillus (17.0%), Corynebacterium (12.0%) and Escherichia-Shigella (11.0%) genera were dominant in the milk collected from farm A. In the case of the milk from farm B, the dominant bacteria belonged to the Acinetobacter genus (21.0%), whereas in the sample from farm C, Escherichia-Shigella (24.8%) and Bacillus (10.3%) dominated the microbiome. An analysis was performed using the PICRUSt tool (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) in order to generate a profile of genes responsible for bacterial metabolism. The conducted analysis confirmed the diversity of the profile of genes responsible for bacterial metabolism in all the tested samples. On the other hand, simultaneous analysis of six KEGG Orthologs (KO), which participated in beta-lactam resistance responsible for antibiotic resistance of bacteria, demonstrated that there is no significant relationship between the predicted occurrence of these orthologs and the place of existence of microorganisms. Therefore, it can be supposed that bacterial resistance to beta-lactam antibiotics occurs regardless of the environmental niche, and that the antibiotic resistance maintained in the population is a factor that shapes the functional structure of the microbial consortia.     

Boundedness of solutions to the critical fully parabolic quasilinear one‐dimensional Keller–Segel system

In this paper we consider a one‐dimensional fully parabolic quasilinear Keller–Segel system with critical nonlinear diffusion. We show uniform‐in‐time boundedness of solutions, which means, that unlike in higher dimensions, there is no critical mass phenomenon in the case of critical diffusion. To this end we utilize estimates from a well‐known Lyapunov functional and a recently introduced new Lyapunov‐like functional in 3 .     

Local collection and end-extensions of models of compositional truth

We introduce a principle of local collection for compositional truth predicates and show that it is arithmetically conservative over the classically compositional theory of truth. This axiom states that upon restriction to formulae of any syntactic complexity, the resulting predicate satisfies full collection. In particular, arguments using collection for the truth predicate applied to sentences occurring in any given (code of a) proof do not suffice to show that the conclusion of that proof is true, in stark contrast to the case of the induction scheme.We analyse various further results concerning end-extensions of models of compositional truth and the collection scheme for the compositional truth predicate.