Preliminary Analysis of a Nano Relativistic Motor

In a recent paper discussing Newton’s third law in the framework of special relativity for charged bodies, it was suggested that one can construct a practical relativistic motor provided high enough charge and current densities are available. As on the macroscopic scale charge density is limited by the phenomena of dielectric breakdown, it was suggested to take advantage of the high charge densities which are available on the microscopic scale. A preliminary analysis of this option denoted "nano relativistic scale" is studied in the current paper.

Parametric study of high-energy ring-shaped electron beams from a laser wakefield accelerator

Laser wakefield accelerators commonly produce on-axis, low-divergence, high-energy electron beams. However, a high charge, annular shaped beam can be trapped outside the bubble and accelerated to high energies. Here we present a parametric study on the production of low-energy-spread, ultra-relativistic electron ring beams in a two-stage gas cell. Ring-shaped beams with energies higher than 750 MeV are observed simultaneously with on axis, continuously injected electrons. Often multiple ring shaped beams with different energies are produced and parametric studies to control the generation and properties of these structures were conducted. Particle tracking and particle-in-cell simulations are used to determine properties of these beams and investigate how they are formed and trapped outside the bubble by the wake produced by on-axis injected electrons. These unusual femtosecond duration, high-charge, high-energy, ring electron beams may find use in beam driven plasma wakefield accelerators and radiation sources.

Mitochondrial Effects in the Liver of C57BL/6 Mice by Low Dose, High Energy, High Charge Irradiation

Galactic cosmic rays are primarily composed of protons (85%), helium (14%), and high charge/high energy ions (HZEs) such as 56Fe, 28Si, and 16O. HZE exposure is a major risk factor for astronauts during deep-space travel due to the possibility of HZE-induced cancer. A systems biology integrated omics approach encompassing transcriptomics, proteomics, lipidomics, and functional biochemical assays was used to identify microenvironmental changes induced by HZE exposure. C57BL/6 mice were placed into six treatment groups and received the following irradiation treatments: 600 MeV/n 56Fe (0.2 Gy), 1 GeV/n 16O (0.2 Gy), 350 MeV/n 28Si (0.2 Gy), 137Cs (1.0 Gy) gamma rays, 137Cs (3.0 Gy) gamma rays, and sham irradiation. Left liver lobes were collected at 30, 60, 120, 270, and 360 days post-irradiation. Analysis of transcriptomic and proteomic data utilizing ingenuity pathway analysis identified multiple pathways involved in mitochondrial function that were altered after HZE irradiation. Lipids also exhibited changes that were linked to mitochondrial function. Molecular assays for mitochondrial Complex I activity showed significant decreases in activity after HZE exposure. HZE-induced mitochondrial dysfunction suggests an increased risk for deep space travel. Microenvironmental and pathway analysis as performed in this research identified possible targets for countermeasures to mitigate risk.

Charged sequence motifs increase affinity towards liquid-liquid phase separation

Protein phase separation has been shown to be a major governing factor in multiple cellular processes, especially ones concerning RNA and RNA-binding proteins. Despite many key observations, the exact structural characteristics of proteins involved in the process are still not fully deciphered. In this work we show that proteins harbouring sequences with specific regions of charged residues are significantly associated with phase separation phenomena. In particular, regions with repetitive arrays of alternating charges (termed charged residue repeats, CRRs) show the strongest association, whereas segments with generally high charge density (charge-dense regions, CDRs) and single alpha-helices (SAHs) show also detectable but weaker connections.It is known to contribute to the formation of membrane-less organelles (MLOs) and to an extent the aggregation of proteins. The causes and consequences of phase separation has been a rigorously researched topic in the last few years, as the condensation of specific phase-separating proteins is known to promote several diseases.In this work we carried out a computational analysis to examine the presence of repetitive segments with high charge density in proteins prone to phase separation. Free resources such as the Charged Single α-Helix (CSAH) web server and the PhaSepDB online database were used to examine possible links between the charged side-chain content of protein sequences and their partition into membrane-less condensates. Furthermore, we carried out the development of a novel algorithm aimed to detect a larger variety of charged protein segments, in order to examine their relationship to the phenomenon. Fisher’s exact test of independence was implemented on several generated data sets to confirm correlation between charged residue repeats (CRRs) and charge-dense regions (CDRs) within human protein sequences and their affinity for phase separation.