The effects of lithium counterdoping on radiation damage and annealing in n(+)p silicon solar cells

Boron-doped silicon n(+)p solar cells were counterdoped with lithium by ion implantation and the resultant n(+)p cells irradiated by 1 MeV electrons. Performance parameters were determined as a function of fluence and a deep level transient spectroscopy (DLTS) study was conducted. The lithium counterdoped cells exhibited significantly increased radiation resistance when compared to boron doped control cells. Isochronal annealing studies of cell performance indicate that significant annealing occurs at 100 C. Isochronal annealing of the deep level defects showed a correlation between a single defect at E sub v + 0.43 eV and the annealing behavior of short circuit current in the counterdoped cells. The annealing behavior was controlled by dissociation and recombination of this defect. The DLTS studies showed that counterdoping with lithium eliminated three deep level defects and resulted in three new defects. The increased radiation resistance of the counterdoped cells is due to the interaction of lithium with oxygen, single vacancies and divacancies. The lithium-oxygen interaction is the most effective in contributing to the increased radiation resistance

Effects of processing and dopant on radiation damage removal in silicon solar cells

Gallium and boron doped silicon solar cells, processed by ion-implantation followed by either laser or furnace anneal were irradiated by 1 MeV electrons and their post-irradiation recovery by thermal annealing determined. During the post-irradiation anneal, gallium-doped cells prepared by both processes recovered more rapidly and exhibited none of the severe reverse annealing observed for similarly processed 2 ohm-cm boron doped cells. Ion-implanted furnace annealed 0.1 ohm-cm boron doped cells exhibited the lowest post-irradiation annealing temperatures (200 C) after irradiation to 5 x 10 to the 13th e(-)/sq cm. The drastically lowered recovery temperature is attributed to the reduced oxygen and carbon content of the 0.1 ohm-cm cells. Analysis based on defect properties and annealing kinetics indicates that further reduction in annealing temperature should be attainable with further reduction in the silicon's carbon and/or divacancy content after irradiation

The Case for Perspicuous Programming

This essay examines the nature of programs, classifies the traditional or enigmatic styles of programming, distinguishing template, prose and literate styles; notes the contrast between batch programs and interactive programs; and highlights the advantages of giving priority in developing interactive programs to the online documentation, and proposes that this documentation should be the principal target of development, with the executable program code being regarded of secondary and consequent

A narrative synthesis of women's out-of-body experiences during childbirth

Introduction Some women have a dissociated, out-of-body experience (OBE) during childbirth, which may be described as seeing the body from above or floating above the body. This review examines this phenomenon using narratives from women who have experienced intrapartum OBEs. Methods A narrative synthesis of qualitative research was employed to systematically synthesize OBE narratives from existing studies. Strict inclusion and exclusion criteria were applied. The included papers were critiqued by 2 of the authors to determine the appropriateness of the narrative synthesis method, procedural transparency, and soundness of the interpretive approach. Results Women experiencing OBEs during labor and birth report a disembodied state in the presence of stress or trauma. Three forms of OBEs are described: floating above the scene, remaining close to the scene, or full separation of a body part from the main body. Women had clear recall of OBEs, describing the experience and point of occurrence. Women who reported OBEs had experienced current or previous traumatic childbirth, or trauma in a non-birth situation. OBEs as prosaic experiences were not identified. Discussion OBEs are part of the lived experience of some women giving birth. The OBEs in this review were trauma related with some women disclosing previous posttraumatic stress disorder (PTSD). It is not evident whether there is a connection between PTSD and OBEs at present, and OBEs may serve as a potential coping mechanism in presence of trauma. Clinicians should legitimize women’s disclosure of OBEs and explore and ascertain their impact, either as a normal coping mechanism or a precursor to perinatal mental illness. Research into the function of OBEs and any relationship to PTSD may assist in early interventions for childbearing women

The Stretched Lens Solar Array for Mars Surface Power

[Abstract] With implementation of the ambitious U.S. space exploration policy underway, new technology to provide power on the Martian surface becomes a priority. Early missions anticipate the use of fuel cells, but the primary power system will rely heavily upon solar arrays. These arrays should have the following characteristics: high efficiency, light weight, high packaging density and be able to withstand low temperature operation in wind and dust storms. This paper will describe how the Stretched Lens Array (SLA) can effectively and reliably provide power on the Mars surface overcoming the environmental challenges

Phenylpyrrole fungicides act on triosephosphate isomerase to induce methylglyoxal stress and alter hybrid histidine kinase activity.

Fludioxonil, a natural product of pyrrolnitrin, is a potent fungicide used on crops worldwide. Drug action requires the presence of a group III hybrid histidine kinase (HHK) and the high osmolarity glycerol (HOG) pathway. We have reported that the drug does not act directly on HHK, but triggers the conversion of the kinase to a phosphatase, which dephosphorylates Ypd1 to constitutively activate HOG signaling. Still, the direct drug target remains unknown and mode of action ill defined. Here, we heterologously expressed a group III HHK, dimorphism-regulating kinase 1 (Drk1) in Saccharomyces cerevisae to delineate fludioxonil's target and action. We show that the drug interferes with triosephosphate isomerase (TPI) causing release of methylglyoxal (MG). MG activates the group III HHK and thus the HOG pathway. Drug action involved Drk1 cysteine 392, as a C392S substitution increased drug resistance in vivo. Drug sensitivity was reversed by dimedone treatment, indicating Drk1 responds in vivo to an aldehydic stress. Fludioxonil treatment triggered elevated cytosolic methylglyoxal. Likewise, methylglyoxal treatment of Drk1-expressing yeast phenocopied treatment with fludioxonil. Fludioxonil directly inhibited TPI and also caused it to release methylglyoxal in vitro. Thus, TPI is a drug target of the phenylpyrrole class of fungicides, inducing elevated MG which alters HHK activity, likely converting the kinase to a phosphatase that acts on Ypd1 to trigger HOG pathway activation and fungal cell death

Fasting regulates EGR1 and protects from glucose- and dexamethasone-dependent sensitization to chemotherapy

Fasting reduces glucose levels and protects mice against chemotoxicity, yet drugs that promote hyperglycemia are widely used in cancer treatment. Here, we show that dexamethasone (Dexa) and rapamycin (Rapa), commonly administered to cancer patients, elevate glucose and sensitize cardiomyocytes and mice to the cancer drug doxorubicin (DXR). Such toxicity can be reversed by reducing circulating glucose levels by fasting or insulin. Furthermore, glucose injections alone reversed the fasting-dependent protection against DXR in mice, indicating that elevated glucose mediates, at least in part, the sensitizing effects of rapamycin and dexamethasone. In yeast, glucose activates protein kinase A (PKA) to accelerate aging by inhibiting transcription factors Msn2/4. Here, we show that fasting or glucose restriction (GR) regulate PKA and AMP-activated protein kinase (AMPK) to protect against DXR in part by activating the mammalian Msn2/4 ortholog early growth response protein 1 (EGR1). Increased expression of the EGR1-regulated cardioprotective peptides atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) in heart tissue may also contribute to DXR resistance. Our findings suggest the existence of a glucose\u2013PKA pathway that inactivates conserved zinc finger stress-resistance transcription factors to sensitize cells to toxins conserved from yeast to mammals. Our findings also describe a toxic role for drugs widely used in cancer treatment that promote hyperglycemia and identify dietary interventions that reverse these effects

Formation of Composite Endothelial Cell–Mesenchymal Stem Cell Islets: A Novel Approach to Promote Islet Revascularization

OBJECTIVE—Mesenchymal stem cells (MSCs) contribute to endothelial cell (EC) migration by producing proteases, thereby paving the way into the tissues for ECs. MSCs were added to our previously described composite EC islets as a potential means to improve their capacity for islet angiogenesis

The TIP30 Protein Complex, Arachidonic Acid and Coenzyme A Are Required for Vesicle Membrane Fusion

Efficient membrane fusion has been successfully mimicked in vitro using artificial membranes and a number of cellular proteins that are currently known to participate in membrane fusion. However, these proteins are not sufficient to promote efficient fusion between biological membranes, indicating that critical fusogenic factors remain unidentified. We have recently identified a TIP30 protein complex containing TIP30, acyl-CoA synthetase long-chain family member 4 (ACSL4) and Endophilin B1 (Endo B1) that promotes the fusion of endocytic vesicles with Rab5a vesicles, which transport endosomal acidification enzymes vacuolar (H+)-ATPases (V-ATPases) to the early endosomes in vivo. Here, we demonstrate that the TIP30 protein complex facilitates the fusion of endocytic vesicles with Rab5a vesicles in vitro. Fusion of the two vesicles also depends on arachidonic acid, coenzyme A and the synthesis of arachidonyl-CoA by ACSL4. Moreover, the TIP30 complex is able to transfer arachidonyl groups onto phosphatidic acid (PA), producing a new lipid species that is capable of inducing close contact between membranes. Together, our data suggest that the TIP30 complex facilitates biological membrane fusion through modification of PA on membranes