Synthesis and Characterization of 2D Atomic Layers

As electronic devices have continued to become smaller, a pressing need has developed for new technologies in order to surpass current size constraints. As such, 2-dimensional materials have become a topic of great interest in experimental device research. Monolayer black phosphorus, or phosphorene, is one such 2D material which shows significant potential as a p-type semiconductor. Phosphorene exhibits a number of unique and desirable electrical properties such as a layer-dependent band gap, high carrier mobility, and anisotropic conductivity. An investigation into optimal growth of black phosphorus, the precursor material to phosphorene, as well as characterization of phosphorene-based devices will be performed

Improving Methods of Doping on Black Phosphorus

Black phosphorus (BP) is a 2D semiconducting material with high carrier mobility. It is usually p-type due to oxidation states near its valence band. Although achieved through other growth methods, n-type doping has not yet been accomplished through the modern chemical vapor transport (CVT) growth method. To address this issue, small amounts of tellurium were added to Red Phosphorus to act as a dopant during the CVT growth process in addition to tin(Sn) and tin(IV) iodide, which facilitate growth. The chemicals are heated up to 600°C and precisely cooled in a 21-hour process, during which BP crystals should form. After successful growth, the synthesized BP is used as a channel material in transistors. N-type transistor characterization will be investigated, which will indicate whether the BP has been doped successfully using the safer and faster CVT growth process

Gaia eclipsing binary and multiple systems. Two-Gaussian models applied to OGLE-III eclipsing binary light curves in the Large Magellanic Cloud

The advent of large scale multi-epoch surveys raises the need for automated light curve (LC) processing. This is particularly true for eclipsing binaries (EBs), which form one of the most populated types of variable objects. The Gaia mission, launched at the end of 2013, is expected to detect of the order of few million EBs over a 5-year mission. We present an automated procedure to characterize EBs based on the geometric morphology of their LCs with two aims: first to study an ensemble of EBs on a statistical ground without the need to model the binary system, and second to enable the automated identification of EBs that display atypical LCs. We model the folded LC geometry of EBs using up to two Gaussian functions for the eclipses and a cosine function for any ellipsoidal-like variability that may be present between the eclipses. The procedure is applied to the OGLE-III data set of EBs in the Large Magellanic Cloud (LMC) as a proof of concept. The bayesian information criterion is used to select the best model among models containing various combinations of those components, as well as to estimate the significance of the components. Based on the two-Gaussian models, EBs with atypical LC geometries are successfully identified in two diagrams, using the Abbe values of the original and residual folded LCs, and the reduced $\chi^2$. Cleaning the data set from the atypical cases and further filtering out LCs that contain non-significant eclipse candidates, the ensemble of EBs can be studied on a statistical ground using the two-Gaussian model parameters. For illustration purposes, we present the distribution of projected eccentricities as a function of orbital period for the OGLE-III set of EBs in the LMC, as well as the distribution of their primary versus secondary eclipse widths.Comment: 20 pages, 29 figures. Submitted to A&

Pulsating star research and the Gaia revolution

In this article we present an overview of the ESA Gaia mission and of the unprecedented impact that Gaia will have on the field of variable star research. We summarise the contents and impact of the first Gaia data release on the description of variability phenomena, with particular emphasis on pulsating star research. The Tycho-Gaia astrometric solution, although limited to 2.1 million stars, has been used in many studies related to pulsating stars. Furthermore a set of 3,194 Cepheids and RR Lyrae stars with their times series have been released. Finally we present the plans for the ongoing study of variable phenomena with Gaia and highlight some of the possible impacts of the second data release on variable, and specifically, pulsating stars.Comment: 12 pages, 4 figures, proceedings for the 22nd Los Alamos Stellar Pulsation Conference Series Meeting "Wide field variability surveys: a 21st-century perspective", held in San Pedro de Atacama, Chile, Nov. 28 - Dec. 2, 201

Safety and disease monitoring biomarkers in Duchenne muscular dystrophy: results from a Phase II trial

Aim: Evaluate the utility of glutamate dehydrogenase (GLDH) and cardiac troponin I as safety biomarkers, and creatine kinase and muscle injury panel as muscle health biomarkers in Duchenne muscular dystrophy. Patients & methods: Data were collected during a Phase II trial of domagrozumab. Results: GLDH was a more specific biomarker for liver injury than alanine aminotransferase. Cardiac troponin I elevations were variable and not sustained, limiting its applicability as a biomarker. Muscle injury panel biomarkers were no more informative than creatine kinase as a muscle health biomarker. Conclusion: Results support the use of GLDH as a specific biomarker for liver injury in patients with Duchenne muscular dystrophy

Lowe syndrome

Lowe syndrome (the oculocerebrorenal syndrome of Lowe, OCRL) is a multisystem disorder characterised by anomalies affecting the eye, the nervous system and the kidney. It is a uncommon, panethnic, X-linked disease, with estimated prevalence in the general population of approximately 1 in 500,000. Bilateral cataract and severe hypotonia are present at birth. In the subsequent weeks or months, a proximal renal tubulopathy (Fanconi-type) becomes evident and the ocular picture may be complicated by glaucoma and cheloids. Psychomotor retardation is evident in childhood, while behavioural problems prevail and renal complications arise in adolescence. The mutation of the gene OCRL1 localized at Xq26.1, coding for the enzyme phosphatidylinositol (4,5) bisphosphate 5 phosphatase, PtdIns (4,5)P2, in the trans-Golgi network is responsible for the disease. Both enzymatic and molecular testing are available for confirmation of the diagnosis and for prenatal detection of the disease. The treatment includes: cataract extraction, glaucoma control, physical and speech therapy, use of drugs to address behavioural problems, and correction of the tubular acidosis and the bone disease with the use of bicarbonate, phosphate, potassium and water. Life span rarely exceeds 40 years

Nephropathic cystinosis associated with cardiomyopathy: A 27-year clinical follow-up

BACKGROUND: Nephropathic cystinosis is an autosomal recessive disease resulting from intracellular accumulation of cystine leading to multiple organ failure. CASE REPORT: We describe the clinical course of a patient managed from the age of six until his death at the age of 33 years. He underwent multiple surgery, including two renal transplants, developed transplant renal artery stenosis that was managed medically, and progressive heart failure at the age of 33 years. His death from a ruptured pseudoaneurysm associated with a restrictive cardiomyopathy is noteworthy. A limited cardiac autopsy revealed the presence of cystine crystals in interstitial cardiac histiocytes and one myocardial cell, along with 1000-fold higher tissue cystine content of the left ventricular myocardium compared to patients without cystinosis, suggesting the possibility of direct cystine mediated metabolic injury

Dual-energy X-ray absorptiometry measures of lean body mass as a biomarker for progression in boys with Duchenne muscular dystrophy

We evaluated whether whole-body dual-energy X-ray absorptiometry (DXA) measures of lean body mass can be used as biomarkers for disease progression and treatment effects in patients with Duchenne muscular dystrophy. This post hoc analysis utilized data from a randomized, 2-period study of domagrozumab versus placebo in 120 ambulatory boys with DMD. DXA measures of lean body mass were obtained from the whole body (excluding head), arms, legs and appendicular skeleton at baseline and every 16 weeks. Treatment effects on DXA measures for domagrozumab versus placebo were assessed at Week 49. At Week 49, domagrozumab statistically significantly increased lean body mass versus placebo in the appendicular skeleton (p = 0.050) and arms (p < 0.001). The relationship between lean body mass at Week 49 and functional endpoints at Week 97 was evaluated. Changes in lean body mass at Week 49 in all regions except arms were significantly correlated with percent change from baseline in 4-stair climb (4SC) at Week 97. DXA-derived percent lean mass at Week 49 also correlated with 4SC and North Star Ambulatory Assessment at Week 97. These data indicate that whole-body DXA measures can be used as biomarkers for treatment effects and disease progression in patients with DMD, and warrant further investigation.Trial registration: ClinicalTrials.gov, NCT02310763; registered 8 December 2014