DEVELOPMENT AND APPLICATION OF A TEST MIXTURE FOR UNTARGETED LIQUID CHROMATOGRAPHY-MASS SPECTROMETRY ANALYSIS OF URINE SAMPLES

Metabolic profiling of complex biological matrices based on liquid chromatography-mass spectrometry (LC-MS) allows detecting a wide range of metabolites with distinct concentrations and physicochemical properties. Given the complexity of samples and the necessity of a comprehensive approach in untargeted metabolomics, quality control strategies are mandatory to obtain high-quality data. The LC-MS performance must be monitored and evaluated to guarantee data reliability. In this study, a test mixture (TM) was developed, systematically evaluated, and applied to untargeted metabolomics of urine samples from individuals suspected of inborn errors of metabolism. The TM was composed of fifteen analytes that eluted across the entire gradient in reversed-phase columns and ionized in positive/negative electrospray modes. It helped set the LC-MS conditions for urine analysis, from sample reconstitution solvent to selecting the MS ion source parameters. The TM quickly indicated column stationary phase degradation during the batch analysis when employed to monitor and evaluate the LC-MS system in an untargeted metabolomic analysis. Thus, in addition to pooled QC samples, a TM can be employed in untargeted metabolomics to rapidly assess the system performance avoiding unnecessary efforts for further data treatment and multivariate analysis of poor-quality data

The study of cracking of sheet polycarbonate by the method of exposure to its surface of adsorption active liquid media

The effect of the composition of a liquid mixture of n-propanol with toluene on the rate of cracking in stressed polycarbonate sheets was studied. It is shown that the dependence of cracking time on stress can be described using equations in which the coefficient values depend on the ratio of the components of this test mixture. The method of wetting the surface of a sheet of monolithic polycarbonate with a test adsorption-active mixture (n-propanol with toluene) can be used not only to assess the quality of polycarbonate products, but also to measure the residual stresses in them. The conclusion is made that the influence of the investigated test liquid mixtures on the cracking of polycarbonate is multifactorial.

Molecular Nearest Neighbors Determine Generalization of Odorant Mixtures

ABSTRACTMost natural odors arise from mixtures of multiple odorants. Some such mixtures are perceived “elementally”, with each odorant component clearly identifiable, while others are perceived “configurally”, with the mixture adopting a perceptual quality distinct from any of the components. While the perceptual similarity of two mixtures is presumably related in some way to the similarity of the corresponding components, given the elemental/configural dichotomy it is unclear if any formal principle can be used to predict mixture similarity. To investigate this problem, we trained mice to respond to a binary reference mixture of structurally similar odorants (S+) and then tested generalization of this response to other structurally related binary test mixtures. Across 5 experiments, we parametrically varied these mixtures in distinct ways to test candidate models for the perceptual similarity of mixtures. The best-performing model predicted behavioral responses by considering, for each component of the S+, only the similarity of the most structurally similar (”nearest neighbor”) component of each test mixture. We conclude that for mixture generalization tasks the olfactory system may deemphasize or discard information about mixture components not perceptually “near” enough to any of those in the S+, consistent with a sparse and elemental rule for perception of structurally-related binary mixtures.

Influence of the composition and agglomeration pressure on the compaction level of the fertilizers based on biomass ash and digestate

The paper presents the results of research aimed at determining the influence of the composition of the fertilizer mixtures and the compaction pressure on the specific density and density index of fertilizer granules. Investigated mixtures were prepared from fly ash from power plant fuelled by biomass and digestate from biogas plant. The urea, sulfur and phosphorite were also added as enhancing additives. For granule samples made on a strength machine, their specific density was determined on a quasifluid-pycnometer. To determine the effect of agglomerate pressure on the compaction process, the absolute density of the materials was omitted. In such case it was needed to introduce a density index AI. Such a presentation of the results obtained has made it possible to clearly determine how the density of the test mixture results in the applied agglomeration pressure. The specific density of the resulting granules was in the range of 0.85-1.27 g/cm3. The determined density index for the given pressure was in the following ranges: 0.44-0.49 g/cm3 (pressure 100MPa), 0.47-0.51 g/cm3 (pressure 150MPa) 0.51 - 0.59 g/cm3 (200MPa pressure). This means that, regardless of the contribution of components to the mixture at the given pressure, a similar degree of compaction was obtained.

Influence of Air Temperature on the Performance of Different Water-Reducing Admixtures with Respect to the Properties of Fresh and Hardened Mortar

The performance of water-reducing admixtures used in concrete is affected by the weather conditions to which the concrete mixture is exposed. The most used WRAs are lignosulfonate, naphthalene, and polycarboxylate. However, they react differently to weather conditions, especially to air temperature. Therefore, it can be useful to evaluate how temperature affects admixture performance. In this study, the performance of three admixtures (naphthalene, lignosulfonate, and polycarboxylate) was evaluated at 15, 25, and 35°C by means of the flow table test, mixture air content, and compressive strength. Moreover, mixture temperature was monitored and time-temperature curves were plotted in order to assess whether the admixtures affected cement hydration reactions at different temperatures. The final results indicate that an increase in temperature leads to an increase in saturation dosage; lignosulfonate had the most pronounced retarding effect, followed by polycarboxylate, and finally, naphthalene, and considering the weather conditions in the area where the study was carried, the final finding would be that the naphthalene-based admixture had the best performance.

Characterization of an Antibody Depletion Assay for Analysis of Bactericidal Antibody Specificity

ABSTRACT Serum bactericidal antibodies are important for protection against systemic Neisseria meningitidis infections. Consequently, identifying the specific targets of bactericidal antibodies is important for understanding protective immunity to meningococcal disease and for vaccine development and evaluation. We have developed a new assay that can be used to investigate the specificity of serum bactericidal antibodies. Prior to testing for bactericidal activity, antibodies specific for a given antigen or group of antigens are depleted from a serum sample by incubation with the antigen(s) bound to the wells of a 96-well microplate. A dilution series of the antigen is bound to the plate to assess the effectiveness of the antigen in removing the bactericidal antibodies. Removal of antibodies with solid-phase antigen prior to bactericidal testing avoids depletion of complement by soluble immune complexes that can form when soluble antigen is present in the bactericidal test mixture (direct inhibition). The parameters associated with this assay are investigated and compared with those associated with a direct-inhibition assay. The bactericidal depletion assay can be an effective tool for studying the specificity of serum bactericidal antibodies.

Direct measurement of particle formation and growth from the oxidation of biogenic emissions

A new facility has been developed to investigate the formation of new particles from the oxidation of volatile organic compounds emitted from vegetation. The facility consists of a biogenic emissions enclosure, an aerosol growth chamber, and the associated instrumentation. Using the facility, new particle formation events have been induced through the reaction of ozone with three different precursor gas mixtures: an α-pinene test mixture and the emissions of a Holm oak (Quercus ilex) specimen and a loblolly pine (Pinus taeda) specimen. The results demonstrate the variability between species in their potential to form new aerosol products. The emissions of Q. ilex specimen resulted in fewer particles than did α-pinene, although the concentration of monoterpenes was roughly equal in both experiments before the addition of ozone. Conversely, the oxidation of P. taeda specimen emissions led to the formation of more particles than either of the other two gas mixtures, despite a lower initial terpenoid concentration. These variations can be attributed to differences in the speciation of the vegetative emissions with respect to the α-pinene mixture and to each other. Specifically, the presence of β-pinene and other slower-reacting monoterpenes probably inhibited particle formation in the Q. ilex experiment, while the presence of sesquiterpenes, including β-caryophyllene, in the emissions of the P. taeda specimen were the likely cause of the more intense particle formation events observed during that experiment.