Conservation laws in Bimetric gravitation theories

In the bimetric theory of gravitation with a flat-space background metric conservation laws for energy and momentum are considered in several different forms. In the bimetric theory with a constant-curvature background metric a previous error in the energy-momentum relation is corrected.     

Birefringence compensation for single-shot 3D profilometry using a full-Stokes imaging polarimeter

Optical Review - We demonstrate a single-shot uniaxial 3D profilometry system that illuminates a sample with a structured polarization pattern and measures the reflected full-Stokes polarimetric...     

Classification of screening systems for lattice vertex operator algebras

Letters in Mathematical Physics - We study and classify systems of certain screening operators arising in a generalized vertex operator algebra, or more generally an abelian intertwining algebra...     

A new microwave-assisted,three-component reaction of 5-aminopyrazole-4-carboxylates: Selective synthesis of substituted 5-aza-9-deaza-adenines

A series of 5-aza-9-deaza- analogues of purine was effectively prepared using highly selective annulation of 1,3,5-triazine ring onto 5-aminopyrazole-4-carboxylates via a one-pot, multicomponent, microwave-assisted approach. The products were obtained in good yields and high purity. This catalyst-free method was demonstrated to be scalable and highly reproducible in different microwave reactors. Some structural features of the prepared compounds were studied in details using dynamic NMR spectroscopy and X-ray crystallography.     

Sweat Based-multiplexed Detection of NPY-Cortisol for Disease Diagnostics and Stress Management

Cortisol and Neuropeptide Y(NPY) are chronobiological markers of stress. Non-invasive tracking of these two biomolecules can provide great insight into an individual's physiological and neurological wellbeing. This work presents the development of a platform that tracks the two biomarkers in ultra-low volumes (5 μL) of sweat using electrochemical impedance spectroscopy (EIS). The sensing platform was able to detect both molecules in their relevant physiological ranges (8.16–141.7 ng/mL and 50–200 pg/mL respectively) with good sensitivity and specificity. This platform is envisioned to aid in the monitoring of pathophysiologies of stress-based disorders.     

HESI-MS/MS Analysis of Phenolic Compounds from Calendula aegyptiaca Fruits Extracts and Evaluation of Their Antioxidant Activities

Considering medicinal plants as an inexhaustible source of active ingredients that may be easily isolated using simple and inexpensive techniques, phytotherapy is becoming increasingly popular. Various experimental approaches and analytical methods have been used to demonstrate that the genus Calendula (Asteraceae) has a particular richness in active ingredients, especially phenolic compounds, which justifies the growing interest in scientific studies on this genus’ species. From a chemical and biological viewpoint, Calendula aegyptiaca is a little-studied plant. For the first time, high-performance liquid chromatography combined with negative electrospray ionization mass spectrometry (HPLC-HESI-MS) was used to analyze methanolic extracts of Calendula aegyptiaca (C. aegyptiaca) fruits. Thirty-five molecules were identified. Flavonoids (47.87%), phenolic acids (5.18%), and saponins (6.47%) formed the majority of these chemicals. Rutin, caffeic acid hexoside, and Soyasaponin βg’ were the most abundant molecules in the fruit methanolic extract, accounting for 17.49% of total flavonoids, 2.32 % of total phenolic acids, and 0.95% of total saponins, respectively. The antioxidant activity of the fruit extracts of C. aegyptiaca was investigated using FRAP, TAC, and DPPH as well as flavonoids and total phenols content. Because the phenolic components were more extractable using polar solvents, the antioxidant activity of the methanolic extract was found to be higher than that of the dichloromethane and hexane extracts. The IC50 value for DPPH of methanolic extract was found to be 0.041 mg·mL⁻¹. Our findings showed that C. aegyptiaca is an important source of physiologically active compounds.     

Mass spectrometric detection of siRNA in plasma samples for doping control purposes

Small interfering ribonucleic acid (siRNA) molecules can effect the expression of any gene by inducing the degradation of mRNA. Therefore, these molecules can be of interest for illicit performance enhancement in sports by affecting different metabolic pathways. An example of an efficient performance-enhancing gene knockdown is the myostatin gene that regulates muscle growth. This study was carried out to provide a tool for the mass spectrometric detection of modified and unmodified siRNA from plasma samples. The oligonucleotides are purified by centrifugal filtration and the use of an miRNA purification kit, followed by flow-injection analysis using an Exactive mass spectrometer to yield the accurate masses of the sense and antisense strands. Although chromatography and sensitive mass spectrometric analysis of oligonucleotides are still challenging, a method was developed and validated that has adequate sensitivity (limit of detection 0.25–1 nmol mL⁻¹) and performance (precision 11–21%, recovery 23–67%) for typical antisense oligonucleotides currently used in clinical studies.     

Determination of low-level agricultural residues in soft drinks and sports drinks by gas chromatography with mass-selective detection: single-laboratory validation

In this study, sponsored by PepsiCo Inc., a method was validated for measurement of 19 pesticide residues in soft drinks and sports drinks by gas chromatography/mass spectrometry (GC/MS) with mass selective detection The pesticide residues determined in this validation were alpha-benzenehexachloride (BHC); beta-BHC; gamma-BHC; delta-BHC; methyl parathion; malathion; chlorpyrifos; aldrin; 2,4-dichlorodiphenyldichloroethylene (DDE); alpha-endosulfan; 4,4-DDE; 2,4-dichlorodiphenyldichloroethane (DDD); dieldrin; ethion; 4,4-DDD; 2,4-dichlorodiphenyltrichloroethylene (DDT); beta-endosulfan; 4,4-DDT; and endosulfan sulfate when spiked into a 200 mL matrix sample at 0.50 microg/L. The samples were diluted with acetonitrile and water, then liquid-liquid phase extracted into petroleum ether. The resulting extract was concentrated to near dryness and diluted with hexane:dichloromethane (50:50). The concentrated samples were purified by gel permeation chromatography. The resulting solution was concentrated and separated on a Florisil substrate. The eluent was concentrated to near dryness, reconstituted to produce a 200-fold concentration, and analyzed using a GC/MS instrument operated in the selective ion monitoring mode. The GC/MS instrument was equipped with a large volume injector capable of injecting 25 microL. External standards prepared in dichloromethane were used for quantification without the need for matrix-matched calibration because the extraction step minimized the matrix effects. The calibration curves for all agricultural residues had coefficients of determination (r2) of greater than or equal to 0.9900, with the exception of one value that was 0.988. Fortification spikes at 0.50 microg/L in 3 matrixes (7UP, Gatorade, and Diet Pepsi) over the course of 2 days (4 days for Gatorade), where n=8 each day, yielded average percent recoveries (and percent relative standard deviations) as follows (n=64): 95.6 (24.8) for alpha-BHC; 91.9 (23.6) for beta-BHC; 89.1 (21.3) for gamma-BHC; 91.7 (19.0) for delta-BHC; 96.2 (20.1) for methylparathion; 99.8 (26.5) for malathion; 120 (27.3) for chlorpyrifos; 103 (31.4) for aldrin; 111 (25.8) for 2,4-DDE; 116 (21.1) for alpha-endosulfan; 132 (34.6) for 4,4-DDE; 123 (34.4) for 2,4-DDD; 104 (20.8) for dieldrin; 141 (31.4) for ethion; 107 (24.5) for 4,4-DDD; 142 (29.2) for 2,4-DDT; 130 (35.9) for beta-endosulfan; 146 (25.3) for 4,4-DDT; and 91.5 (21.6) for endosulfansulfate.