Synthesis of the four enantiomers of diethyl 1,2-di(N-Boc-amino)propylphosphonates

A simple and efficient synthetic strategy to all four enantiomerically pure diethyl 1,2-di(N-Boc-amino)propylphosphonates has been elaborated starting from the corresponding N-[(R)-(1-phenylethyl)]aziridine-(2S)- and N-[(S)-(1-phenylethyl)]aziridine-(2R)-carboxaldehydes, employing a one-pot three-components Kabachnik-Fields reaction followed by the hydrogenolytic removal of the chiral auxiliary and aziridine ring opening with simultaneous protection of the amino groups as the N-Boc derivatives.     

The hydrogen‐bonding network in deacetyl­cephalothin

The structural analysis of deacetyl­cephalothin [systematic name: (6R,7R)‐3‐hydroxy­methyl‐8‐oxo‐7‐(2‐thio­phen‐2‐yl­acetyl­amino)‐5‐thia‐1‐aza­bicyclo­[4.2.0]oct‐2‐ene‐2‐carboxylic acid], C₁₄H₁₄N₂O₅S₂, shows that the geometry of the central bicyclic moiety is close to the geometry exhibited by other biologically active cephalosporin antibiotics. The mol­ecules are arranged in a helical chain running parallel to the 2₁ axis via a strong O—H⋯O hydrogen bond. The main helices are zipped together via N—H⋯O inter­actions, forming infinite layers. The supramolecular architecture is stabilized by O—H⋯S and C—H⋯O hydrogen bonds.     

Lévy-driven GPS queues with heavy-tailed input

In this paper, we derive exact large buffer asymptotics for a two-class generalized processor sharing (GPS) model, under the assumption that the input traffic streams generated by both classes correspond to heavy-tailed Lévy processes. Four scenarios need to be distinguished, which differ in terms of (i) the level of heavy-tailedness of the driving Lévy processes as well as (ii) the values of the corresponding mean rates relative to the GPS weights. The derived results are illustrated by two important special cases, in which the queues’ inputs are modeled by heavy-tailed compound Poisson processes and by \(\alpha \)-stable Lévy motions.     

Liquid chromatography tandem mass spectrometry with ion trap and triple quadrupole analyzers for determination of thyreostatic drugs in urine and muscle tissue

Liquid chromatography tandem mass spectrometry methods were developed and validated to screen for and confirm residues of the thyreostatic drugs: tapazole, thiouracil, methylthiouracil, propylthiouracil, and phenylthiouracil in bovine and porcine urine and muscle tissues using dimethylthiouracil as internal standard. Thyreostats were extracted from urine samples with diethyl ether after derivatisation with 3-iodobenzylbromide in basic medium (pH 8.0) and analyzed by gradient elution on a Nucleosil C18 column with ion trap mass spectrometry detection using an electrospray source and triple quadrupole MS detection with turbo spray source. Thyreostats were extracted from muscle tissue with methanol, the denaturation of matrix protein was performed and then the same steps as for the urine samples were carried out. The methods were validated in accordance with the Commission Decision 2002/657/EC. Good thyreostats recoveries were obtained (from 82% to 117%) as well as acceptable within-lab reproducibility. The values of the decision limit CCα and the detection capability CCβ of five thyreostatic drugs are found to be below the recommended concentration set at 10 μg L(-1) (kg(-1)). The results of the validation demonstrate that liquid chromatography mass spectrometry with ion trap detection does not meet the criteria for confirmation for some thyreostats and therefore was applied for screening purpose only.     

Experimental and Theoretical Investigation of Vibrational Spectra of Coordination Polymers Based on TCE‐TTF

The room‐temperature infrared and Raman spectra of a series of four isostructural polymeric salts of 2,3,6,7‐tetrakis(2‐cyanoethylthio)‐tetrathiafulvalene (TCE‐TTF) with paramagnetic (Co^II, Mn^II) and diamagnetic (Zn^II, Cd^II) ions, together with BF₄^? or ClO₄^? anions are reported. Infrared and Raman‐active modes are identified and assigned based on theoretical calculations for neutral and ionized TCE‐TTF using density functional theory (DFT) methods. It is confirmed that the TCE‐TTF molecules in all the materials investigated are fully ionized and interact in the crystal structure through cyanoethylthio groups. The vibrational modes related to the C?C stretching vibrations of TCE‐TTF are analyzed assuming the occurrence of electron–molecular vibration coupling (EMV). The presence of the antisymmetric C?C dimeric mode provides evidence that charge transfer takes place between TCE‐TTF molecules belonging to neighboring polymeric networks.     

N- Hydroxyphthalimide and transition metal salts as catalysts of the liquid-phase oxidation of 1-methoxy-4-(1-methylethyl)benzene with oxygen

The oxidation process of 1-methoxy-4-(1-methylethyl)benzene catalysed by N-hydroxyphthalimide (NHPI) or NHPI in combination with Cu(II), Co(II), Mn(II) and Fe(II) salts was studied. The effects of the amount of catalyst and the temperature were determined. 1-Methyl-1-(4-methoxyphenyl)ethyl hydroperoxide was obtained in a yield of 73 mol% when 1-methoxy-4-(1-methylethyl)benzene was oxidised for 3 h at 60°C in acetonitrile as a solvent in the presence of NHPI. 1-(4-Methoxyphenyl)ethanone with high selectivity up to 68–75 mol%, but low yield amounting to 11 mol% was obtained when 1-methoxy-4-(1-methylethyl)benzene was oxidised in the presence of the NHPI/Cu(II) system at 120°C.      

Does Nitrogen Fertilization Affect the Secondary Structures of Gliadin Proteins in Hypoallergenic Wheat?

One of the macronutrients indispensable for plant growth and development is nitrogen (N). It is responsible for starch and storage protein (gliadins and glutenins) biosynthesis and, in consequence, influences kernels’ quality and yields. However, applying N-fertilizers increases gluten content in wheat, and it may intensify the risk of developing allergy symptoms in gluten-sensitive individuals. The purpose of our research was to analyse whether and how the elimination of N-fertilizers during the cultivation of wasko.gl− wheat (modified genotype lacking ω-gliadins) changes the secondary structures of gliadin proteins. To this aim, using the FT-Raman technique, we examined flour and gliadin protein extracts obtained from kernels of two winter wheat lines: wasko.gl+ (with a full set of gliadin proteins) and wasko.gl− (without ω-gliadin fraction) cultivated on two different N-fertilization levels—0 and 120 kg N·ha⁻¹. On the basis of the obtained results, we proved that nitrogen fertilization does not have a major impact on the stability of the secondary structures of gliadin proteins for wasko.gl− wheat line with reduced allergenic properties. Furthermore, the results presented herein suggest the possibility of increasing the stability of glutenin structures as a result of the N-fertilization of wasko.gl− wheat line, which gives hope for its use in the production of wheat articles devoted to people suffering from diseases related to gluten sensitivity.     

Antibody–Ferrocene Conjugates as a Platform for Electro-Chemical Detection of Low-Density Lipoprotein

Low-density lipoprotein (LDL) is a cardiac biomarker identified in the pathology of cardiovascular disease (CVD). Typically, the level of LDL is calculated using the Friedewald relationship based on measured values of total cholesterol, high-density lipoproteins (HDL), and triglycerides. Unfortunately, this approach leads to some errors in calculation. Therefore, direct methods that can be used for fast and accurate detection of LDL are needed. The purpose of this study was to develop an electrochemical platform for the detection of LDL based on an antibody–ferrocene conjugate. An anti-apolipoprotein B-100 antibody labeled with ferrocene was covalently immobilized on the layer of 4-aminothiophenol (4-ATP) on the surface of gold electrodes. Upon interaction between LDL and the antibody–ferrocene conjugate, a decrease in the ferrocene redox signal registered by square wave voltammetry was observed, which depends linearly on the concentration from 0.01 ng/mL to 1.0 ng/mL. The obtained limit of detection was equal to 0.53 ng/mL. Moreover, the satisfied selectivity toward human serum albumin (HSA), HDL, and malondialdehyde-modified low-density lipoprotein (MDA-LDL) was observed. In addition, the acceptable recovery rates of LDL in human serum samples indicate the possible application of immunosensors presented in clinical diagnostics.