Arnowitt–Deser–Misner representation and Hamiltonian analysis of covariant renormalizable gravity

We study the recently proposed Covariant Renormalizable Gravity (CRG), which aims to provide a generally covariant ultraviolet completion of general relativity. We obtain a spacetime decomposed form—an Arnowitt–Deser–Misner (ADM) representation—of the CRG action. The action is found to contain time derivatives of the gravitational fields up to fourth order. Some ways to reduce the order of these time derivatives are considered. The resulting action is analyzed using the Hamiltonian formalism, which was originally adapted for constrained theories by Dirac. It is shown that the theory has a consistent set of constraints. It is, however, found that the theory exhibits four propagating physical degrees of freedom. This is one degree of freedom more than in Hořava–Lifshitz (HL) gravity and two more propagating modes than in general relativity. One extra physical degree of freedom has its origin in the higher order nature of the CRG action. The other extra propagating mode is a consequence of a projectability condition similarly as in HL gravity. Some additional gauge symmetry may need to be introduced in order to get rid of the extra gravitational degrees of freedom.     

Green Synthesis,Characterization, and Antibacterial Properties of Silver Nanoparticles Obtained by Using Diverse Varieties of Cannabis sativa Leaf Extracts

Cannabis sativa L. (hemp) is a plant used in the textile industry and green building material industry, as well as for the phytoremediation of soil, medical treatments, and supplementary food products. The synergistic effect of terpenes, flavonoids, and cannabinoids in hemp extracts may mediate the biogenic synthesis of metal nanoparticles. In this study, the chemical composition of aqueous leaf extracts of three varieties of Romanian hemp (two monoecious, and one dioecious) have been determined by Fourier-Transformed Infrared spectroscopy (FT-IR), high-performance liquid chromatography, and mass spectrometry (UHPLC-DAD-MS). Then, their capability to mediate the green synthesis of silver nanoparticles (AgNPs) and their pottential antibacterial applications were evaluated. The average antioxidant capacity of the extracts had 18.4 ± 3.9% inhibition determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH^•) and 78.2 ± 4.1% determined by 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS™) assays. The total polyphenolic content of the extracts was 1642 ± 32 mg gallic acid equivalent (GAE) L⁻¹. After this, these extracts were reacted with an aqueous solution of AgNO₃ resulting in AgNPs, which were characterized by UV−VIS spectroscopy, FT-IR, scanning electron microscopy (SEM-EDX), and dynamic light scattering (DLS). The results demonstrated obtaining spherical, stable AgNPs with a diameter of less than 69 nm and an absorbance peak at 435 nm. The mixture of extracts and AgNPs showed a superior antioxidant capacity of 2.3 ± 0.4% inhibition determined by the DPPH^• assay, 88.5 ± 0.9% inhibition as determined by the ABTS^•+ assay, and a good antibacterial activity against several human pathogens: Escherichia coli, Klebsiella pneumoniae, Pseudomonas fluorescens, and Staphylococcus aureus.     

Ganglioside analysis in body fluids by liquid-phase separation techniques hyphenated to mass spectrometry

The expression of gangliosides in central nervous system is a few times higher than in the extraneural tissue, a characteristic highlighting their major role at this level. Although in very low amounts, gangliosides are ubiquitously distributed in body fluids too, where, depending on many factors, including pathological states, their composition fluctuates, thus having diagnostic value. Ganglioside investigation in biological fluids, which, except for cerebrospinal fluid (CSF), may be sampled noninvasively, was for years impeded by the limited sensitivity of the analytical instrumentation available in glycomics. However, because the last decade has witnessed significant developments in biological mass spectrometry (MS) and the hyphenated separation techniques, marked by a major increase in sensitivity, reproducibility, and data reliability, ganglioside research started to be focused on biofluid analysis by separation techniques coupled to MS. In this context, our review presents the achievements in this emerging field of gangliosidomics, with a particular emphasis on modern liquid chromatography (LC), thin-layer chromatography, hydrophilic interaction LC, and ion mobility separation coupled to high-performance MS, as well as the results generated by these systems and allied experimental procedures in profiling and structural analysis of gangliosides in healthy or diseased body fluids, such as CSF, plasma/serum, and milk.