Understanding Molecular Bonding in Vitamin B12 Using X-Ray Spectroscopy

It is often difficult to accurately describe the electronic configuration of large molecules like cobalamin (Vitamin B12). By defining the electronic and geometric structure of a molecule using X-ray spectroscopy, we can better understand how that molecule behaves. Cobalamin is a molecule of interest because it typically displays dehalogenating properties in the body. By understanding more of how cobalamin analogues operate, it becomes possible to know their chemical properties and reactions

Identification of InSight 2016 and 2018 Bacterial Isolates

The Committee on Space Research is the international body that puts forth planetary protection policy to prevent the forward contamination of other planetary bodies. The Biotechnology and Planetary Protection Group (BPPG) at the NASA Jet Propulsion Laboratory strictly abides by these policies to minimize forward contamination by implementing microbial reduction procedures. In conjunction with microbial reduction, BPPG also routinely samples spacecraft and associated surfaces throughout assembly, testing, and launch operations to ensure that spacecraft bioburden is below an acceptable threshold. The NASA Standard Assay requires organisms collected from the spacecraft to be processed using sonication, heat shock, and subsequent growth for 72 hours. Counts of the resulting colonies are then used to calculate bioburden, and a subset of these colonies are archived for long-term storage and identification. Sampling events for the recent InSight (Interior Exploration using Seismic Investigations, Geodesy, and Heat Transport) mission to Mars resulted in the archiving of 1,293 bacterial isolates. During this internship, these 1,293 isolates were identified using a MALDI-TOF (matrix-assisted laser desorption/ionization time-of-flight) mass spectrometry and 16S rRNA sequencing hybrid approach. The resulting bacterial identities, along with metadata collected during the sampling events, were then used to compare the species reoccurrence between different parts of the spacecraft, different facilities involved in spacecraft assembly (JPL, Lockheed Martin, Vandenberg Air Force Base, Astrotech Space Operations), and the two separate InSight launch campaigns (2016 and 2018)

Microorganisms Associated with Mars-Bound Spacecraft: Preservation, Identification, Characterization

The Biotechnology and Planetary Protection Group (BPPG) at the Jet Propulsion Lab (JPL) focuses on avoiding forward and backward contamination between Earth and extraterrestrial bodies, ensuring that planetary bodies can be studied in their natural state in the future. This endeavor involves sampling organisms from Mars bound spacecraft during assembly, testing, and launch operations, archiving the organisms for long-term storage, and identifying the organisms through MALDI-TOF (matrix-assisted laser desorption and ionization time of flight) mass spectrometry. Because the MALDI-TOF database is primarily composed of clinical samples, it is necessary to continuously update the database with isolates collected from Marsbound spacecraft to make future identification efforts at BPPG easier. During this internship, efforts were made to continue updating the in-house MALDI-TOF database by studying microbial samples taken from spacecraft hardware and flight facilities. In addition, novel organisms from spacecraft required further biochemical and taxonomical identification, 16S rRNA sequencing, and addition of new spectral profiles to the MALDI database. These efforts culminated in a more comprehensive JPL in-house database, the characterization of several novel organisms, and the proper identification and storage of numerous microbial samples in accordance to BPPG standards

In vitro Efficacy of a Novel Guanosine-Analog Phosphonate

Actinic keratosis, a frequent carcinoma in situ of non-melanoma skin cancer (NMSC), can transform into life-threatening cutaneous squamous cell carcinoma. Current treatment is limited due to low complete clearance rates and asks for novel therapeutic concepts; the novel purine nucleotide analogue OxBu may be an option. In order to enhance skin penetration, solid lipid nanoparticles (SLN, 136-156 nm) were produced with an OxBu entrapment efficiency of 96.5 ± 0.1%. For improved preclinical evaluation, we combined tissue engineering with clinically used keratin-18 quantification. Three doses of 10-3 mol/l OxBu, dissolved in phosphate-buffered saline as well as loaded to SLN, were effective on reconstructed NMSC. Tumour response and apoptosis induction were evaluated by an increase in caspase-cleaved fragment of keratin-18, caspase-7 activation as well as by reduced expression of matrix metallopeptidase-2 and Ki-67. OxBu efficacy was superior to equimolar 5-fluorouracil solution, and thus the drug should be subjected to the next step in preclinical evaluation

Competing orders in PZN-xPT and PMN-xPT relaxor ferroelectrics

Neutron and x-ray scattering studies on relaxor ferroelectric systems Pb(Zn$_{1/3}$Nb$_{2/3}$)O$_3$ (PZN), Pb(Mg$_{1/3}$Nb$_{2/3}$)O$_3$ (PMN), and their solid solutions with PbTiO$_3$ (PT) have shown that inhomogeneities and disorder play important roles in the materials properties. Although a long-range polar order can be established at low temperature - sometimes with the help of an external electric field; short-range local structures called the ``polar nano-regions'' (PNR) still persist. Both the bulk structure and the PNR have been studied in details. The coexistence and competition of long- and short-range polar orders and how they affect the structural and dynamical properties of relaxor materials are discussed.Comment: Article submitted for JPSJ Special Topics (Novel States of Matter Induced by Frustration

The European Training Network ETUDE (Encompassing Training in fUnctional Disorders across Europe) : a new research and training program of the EURONET-SOMA network recruiting 15 early stage researchers

Contains fulltext : 232532.pdf (Publisher’s version ) (Open Access

A novel path to runaway electron mitigation via deuterium injection and current-driven MHD instability

Relativistic electron (RE) beams at high current density (low safety factor, q ( a )) yet very low free-electron density accessed with D-2 secondary injection in the DIII-D and JET tokamak are found to exhibit large-scale MHD instabilities that benignly terminate the RE beam. In JET, this technique has enabled termination of MA-level RE currents without measurable first-wall heating. This scenario thus offers an unexpected alternate pathway to achieve RE mitigation without collisional dissipation. Benign termination is explained by two synergistic effects. First, during the MHD-driven RE loss events both experiment and MHD orbit-loss modeling supports a significant increase in the wetted area of the RE loss. Second, as previously identified at JET and DIII-D, the fast kink loss timescale precludes RE beam regeneration and the resulting dangerous conversion of magnetic to RE kinetic energy. During the termination, the RE kinetic energy is lost to the wall, but the current fully transfers to the cold bulk thus enabling benign Ohmic dissipation of the magnetic energy on longer timescales via a conventional current quench. Hydrogenic (D-2) secondary injection is found to be the only injected species that enables access to the benign termination. D-2 injection: (1) facilitates access to low q ( a ) in existing devices (via reduced collisionality & resistivity), (2) minimizes the RE avalanche by 'purging' the high-Z atoms from the RE beam, (3) drives recombination of the background plasma, reducing the density and Alfven time, thus accelerating the MHD growth. This phenomenon is found to be accessible when crossing the low q ( a ) stability boundary with rising current, falling toroidal field, or contracting minor radius-the latter being the expected scenario for vertically unstable RE beams in ITER. While unexpected, this path scales favorably to fusion-grade tokamaks and offers a novel RE mitigation scenario in principle accessible with the day-one disruption mitigation system of ITER

OmpR controls Yersinia enterocolitica motility by positive regulation of flhDC expression

Flagella and invasin play important roles during the early stages of infection by the enteric pathogen Yersinia enterocolitica. Our previous study demonstrated that OmpR negatively regulates invasin gene expression at the transcriptional level. The present study focused on the role of OmpR in the regulation of flagella expression. Motility assays and microscopic observations revealed that an ompR mutant strain exhibits a non-motile phenotype due to the lack of flagella. An analysis of flhDC::lacZYA chromosomal fusions demonstrated a decrease in flhDC expression in ompR mutant cells, suggesting a role for OmpR in the positive control of flagellar master operon flhDC, which is in contrast to the negative role it plays in Escherichia coli. Moreover, high temperature or osmolarity and low pH decreased flhDC expression and OmpR was not required for the response to these factors. Evidence from an examination of the DNA binding properties of OmpR in vitro indicated that the mechanism by which OmpR regulates flhDC is direct. Electrophoretic mobility shift assays confirmed that OmpR binds specifically to the flhDC promoter region and suggested the presence of more than one OmpR-binding site. In addition, phosphorylation of OmpR by acetyl-P appeared to stimulate the binding abilities of OmpR. Together with the results of our previous studies revealing the negative role of OmpR in the regulation of invasin expression, these findings support a model in which invasion and motility might be reciprocally regulated by OmpR