Ion implantation of epitaxial GaN films: damage, doping and activation

Single-crystal GaN films grown on AlN buffer layers previously deposited on 6H-SiC(0001) were studied for radiation damage and its recovery using Rutherford backscattering/channeling, photoluminescence, and cross-sectional TEM. The highest fluence of (1e15 cm{sup -2}) 110 keV Mg and 160 keV Si produced little damage at implantation temperature 550 C. RT damage was higher for same fluences compared to 550 C implantation. The damage was partially annealed by RTA at 1000 C, however, this was not enough to recover the PL signal even for the lowest fluence (1e14 cm{sup -2}). XTEM of as-implanted samples revealed small clusters of defects extended beyond the projected ion range. To recover damage completely, perhaps one needs to go either much higher RTA temperature and/or implant samples in a smaller fluence increment and anneal in between implants to recover the damage

TFEB induces mitochondrial itaconate synthesis to suppress bacterial growth in macrophages

Successful elimination of bacteria in phagocytes occurs in the phago-lysosomal system, but also depends on mitochondrial pathways. Yet, how these two organelle systems communicate is largely unknown. Here we identify the lysosomal biogenesis factor transcription factor EB (TFEB) as regulator for phago-lysosome-mitochondria crosstalk in macrophages. By combining cellular imaging and metabolic profiling, we find that TFEB activation, in response to bacterial stimuli, promotes the transcription of aconitate decarboxylase (Acod1, Irg1) and synthesis of its product itaconate, a mitochondrial metabolite with antimicrobial activity. Activation of the TFEB–Irg1–itaconate signalling axis reduces the survival of the intravacuolar pathogen Salmonella enterica serovar Typhimurium. TFEB-driven itaconate is subsequently transferred via the Irg1-Rab32–BLOC3 system into the Salmonella-containing vacuole, thereby exposing the pathogen to elevated itaconate levels. By activating itaconate production, TFEB selectively restricts proliferating Salmonella, a bacterial subpopulation that normally escapes macrophage control, which contrasts TFEB’s role in autophagy-mediated pathogen degradation. Together, our data define a TFEB-driven metabolic pathway between phago-lysosomes and mitochondria that restrains Salmonella Typhimurium burden in macrophages in vitro and in vivo

Mitochondrial Priming by CD28

T cell receptor (TCR) signaling without CD28 can elicit primary effector T cells, but memory T cells generated during this process are anergic, failing to respond to secondary antigen exposure. We show that, upon T cell activation, CD28 transiently promotes expression of carnitine palmitoyltransferase 1a (Cpt1a), an enzyme that facilitates mitochondrial fatty acid oxidation (FAO), before the first cell division, coinciding with mitochondrial elongation and enhanced spare respiratory capacity (SRC). microRNA-33 (miR33), a target of thioredoxin-interacting protein (TXNIP), attenuates Cpt1a expression in the absence of CD28, resulting in cells that thereafter are metabolically compromised during reactivation or periods of increased bioenergetic demand. Early CD28-dependent mitochondrial engagement is needed for T cells to remodel cristae, develop SRC, and rapidly produce cytokines upon restimulation—cardinal features of protective memory T cells. Our data show that initial CD28 signals during T cell activation prime mitochondria with latent metabolic capacity that is essential for future T cell responses

Blind trials of computer-assisted structure elucidation software

<p>Abstract</p> <p>Background</p> <p>One of the largest challenges in chemistry today remains that of efficiently mining through vast amounts of data in order to elucidate the chemical structure for an unknown compound. The elucidated candidate compound must be fully consistent with the data and any other competing candidates efficiently eliminated without doubt by using additional data if necessary. It has become increasingly necessary to incorporate an <it>in silico </it>structure generation and verification tool to facilitate this elucidation process. An effective structure elucidation software technology aims to mimic the skills of a human in interpreting the complex nature of spectral data while producing a solution within a reasonable amount of time. This type of software is known as computer-assisted structure elucidation or CASE software. A systematic trial of the ACD/Structure Elucidator CASE software was conducted over an extended period of time by analysing a set of single and double-blind trials submitted by a global audience of scientists. The purpose of the blind trials was to reduce subjective bias. Double-blind trials comprised of data where the candidate compound was unknown to both the submitting scientist and the analyst. The level of expertise of the submitting scientist ranged from novice to expert structure elucidation specialists with experience in pharmaceutical, industrial, government and academic environments.</p> <p>Results</p> <p>Beginning in 2003, and for the following nine years, the algorithms and software technology contained within ACD/Structure Elucidator have been tested against 112 data sets; many of these were unique challenges. Of these challenges 9% were double-blind trials. The results of eighteen of the single-blind trials were investigated in detail and included problems of a diverse nature with many of the specific challenges associated with algorithmic structure elucidation such as deficiency in protons, structure symmetry, a large number of heteroatoms and poor quality spectral data.</p> <p>Conclusion</p> <p>When applied to a complex set of blind trials, ACD/Structure Elucidator was shown to be a very useful tool in advancing the computer's contribution to elucidating a candidate structure from a set of spectral data (NMR and MS) for an unknown. The synergistic interaction between humans and computers can be highly beneficial in terms of less biased approaches to elucidation as well as dramatic improvements in speed and throughput. In those cases where multiple candidate structures exist, ACD/Structure Elucidator is equipped to validate the correct structure and eliminate inconsistent candidates. Full elucidation can generally be performed in less than two hours; this includes the average spectral data processing time and data input.</p

The poetry of Walter de la Mare

SIGLEAvailable from British Library Document Supply Centre- DSC:D87854 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Individual Differences in Disgust Sensitivity Do Not Influence Moral Reasoning, but a Discipline-Specific Ethics Course Does

The purpose of this research study was to determine undergraduate students’ perceptions of ethical dilemmas as a means of measuring general concern for leadership ethics within the marketplace. With the end goal of identifying best practices for ethics education in business and to further aid our understanding of how individual factors, such as disgust sensitivity, can alter students’ moral assessments, we measured the relationship between emotion and cognition in affecting ethical decision making. We found specific coursework in business ethics can produce a significant gain in moral reasoning. These results suggest that in the absence of strong moral intuitions, discipline-specific ethics coursework can lead to more postconventional moral decision making