Some Remarks on a Nongeometrical Interpretation of Gravity and the Flatness Problem

In a nongeometrical interpretation of gravity,the metric g(x) = + (x)is interpreted as an effective metric, whereas(x) is interpreted as afundamental gravitational field, propagated in spacetime which isactually flat. Some advantages and disadvantages of suchan interpretation are discussed. The main advantage isa natural resolution of the flatness problem.     

Assays of ligand-human serum albumin binding using pulsed ultrafiltration and liquid chromatography-mass spectrometry

Two approaches were utilized to increase the throughput of pulsed ultrafiltration assays of ligand binding to human serum albumin, reducing the volume of the ultrafiltration chamber and combining pulsed ultrafiltration with high performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (LC-MS). Affinity constants for binding of ligands to human serum albumin were determined using pulsed ultrafiltration with ultraviolet absorbance detection. The first affinity constants (Ka1) were measured for the binding of dansylsarcosine, dansylamide, 7-anilinocoumarin-4-acetic acid and warfarin, and were determined to be 1.8 x 105, 5 x 104, 8 x 104, and 2.0 x 105 M-1, respectively. The throughput of pulsed ultrafiltration analyses was tripled compared to previous pulsed ultrafiltration measurements by reducing the volume of the chamber. In addition, the use of LC-MS with pulsed ultrafiltration permitted the simultaneous comparison and rank ordering of ligand mixtures for binding to serum albumin. For example, the throughput of these pulsed ultrafiltration measurements was tripled by analyzing three ligands as a mixture.     

Indirect determination of bromide by diffusion flow injection analysis with amperometric detection

Summary A rapid, indirect diffusion flow injection analysis (FIA) method with amperometric detection has been developed for the selective and sensitive determination of Br^–. The method is based on permanganate oxidation of Br^– to bromine. Bromine diffuses through a PTFE membrane and is quantified amperometrically at a platinum working electrode. Calibration graphs were linear up to the maximum concentration of Br^– investigated (10.0 mmol/l). The precision of the technique was better than a relative standard deviation of 0.7% at 10.0 mol/l, with a throughput of 30 samples per hour. The effects of temperature, acidity, working potential, composition of the reagent solution and interferents on the FIA signals were studied. The catalytic effect of Cl^– on the permanganate oxidation of the analyte was utilized to lower the detection limit to 1 mol/l (16 ng Br^–). Similar detection limits were achieved by combining the effects of higher acidity (4.0 mol/l H₂SO₄) and elevated temperatures (40°C). The method was successfully applied to the determination of Br^– in chloride and other reagents, as well as in natural waters.     

Synthesis and characterization of biodegradable poly(butylene succinate-co-butylene fumarate)s

A series of aliphatic biodegradable polyesters modified with fumaric residues was synthesized by transesterification in the melt of dimethyl succinate, dimethyl fumarate and 1,4-butanediol. The amount of unsaturation, originating from the fumaric acid residues in the polyesters chains was varied from 5 to 20 mol%. The molecular structure and composition of the polyesters were determined by ¹H NMR spectroscopy. The effects of the content of fumaric residues on the thermal and thermo-oxidative properties of the synthesized polyesters were investigated using differential scanning calorimetry (DSC) and thermogravimetric analysis. The degree of crystallinity was determined by DSC and wide angle X-ray scattering. The degrees of crystallinity of the unsaturated copolyesters were reduced, while the melting temperatures were higher in comparison to poly(butylene succinate). Biodegradation of the synthesized copolyesters was estimated in enzymatic degradation tests using a buffer solution with Rhizopus arrhizus lipase at 37 °C. Although the degree of crystallinity of the copolyesters decreases slightly with increasing unsaturation, the biodegradation is not enhanced suggesting that not only the chemical structure and molecular stiffness but also the morphology of the spherulites has an influence on the biodegradation properties. The highest biodegradability was observed for the copolyesters containing 5 and 10 mol% of fumarate units.     

Chiral-symmetry restoration in the linear sigma model at nonzero temperature and baryon density

We study the chiral phase transition in the linear sigma model with 2 quark flavors and N _c colors. One-loop calculations predict a first-order phase transition at both μ = 0 and μ ≠ 0. We also discuss the phase diagram and make a comparison with a thermal parametrization of existing heavy-ion experimental data.     

Synthesis and Biological Activity of a Cytostatic Inhibitor of MLLr Leukemia Targeting the DOT1L Protein

Histone methyltransferase DOT1L catalyzes mono-, di- and trimethylation of histone 3 at lysine residue 79 (H3K79) and hypermethylation of H3K79 has been linked to the development of acute leukemias characterized by the MLL (mixed-lineage leukemia) rearrangements (MLLr cells). The inhibition of H3K79 methylation inhibits MLLr cells proliferation, and an inhibitor specific for DOT1L, pinometostat, was in clinical trials (Phase Ib/II). However, the compound showed poor pharmacological properties. Thus, there is a need to find new potent inhibitors of DOT1L for the treatment of rearranged leukemias. Here we present the design, synthesis, and biological evaluation of a small molecule that inhibits in the nM level the enzymatic activity of hDOT1L, H3K79 methylation in MLLr cells with comparable potency to pinometostat, associated with improved metabolic stability and a characteristic cytostatic effect.     

In vitro anti-quorum sensing activity of phytol

Anti-quorum sensing activity of the diterpene phytol was evaluated in vitro for the first time. This compound (at three sub-MIC concentrations – 0.5, 0.25 and 0.125 MIC, respectively) reduced the formation of Pseudomonas aeruginosa PAO1 biofilm in the range of 74.00–84.33% exhibiting higher activity than the both positive controls used, streptomycin and ampicillin. Phytol (0.5 MIC) also effectively reduced P. aeruginosa twitching and flagella motility. Indeed, the bacteria treated were incapable of producing a twitching zone and had almost round, smooth and regular colony edges. Finally, the tested compound (0.5 MIC) exhibited good P. aeruginosa pyocyanin inhibitory activity (51.94%) practically to the same extent as streptomycin (52.09%). According to the experimental data obtained, this phytol property may inspire design of medical foods targeting P. aeruginosa quorum sensing activity.     

Copper Adsorption on Lignin for the Removal of Hydrogen Sulfide

Lignin is currently an underutilized part of biomass; thus, further research into lignin could benefit both scientific and commercial endeavors. The present study investigated the potential of kraft lignin as a support material for the removal of hydrogen sulfide (H₂S) from gaseous streams, such as biogas. The removal of H₂S was enabled by copper ions that were previously adsorbed on kraft lignin. Copper adsorption was based on two different strategies: either directly on lignin particles or by precipitating lignin from a solution in the presence of copper. The H₂S concentration after the adsorption column was studied using proton-transfer-reaction mass spectrometry, while the mechanisms involved in the H₂S adsorption were studied with X-ray photoelectron spectroscopy. It was determined that elemental sulfur was obtained during the H₂S adsorption in the presence of kraft lignin and the differences relative to the adsorption on porous silica as a control are discussed. For kraft lignin, only a relatively low removal capacity of 2 mg of H₂S per gram was identified, but certain possibilities to increase the removal capacity are discussed.