322 research outputs found

    High Efficiency InP Solar Cells from Low Toxicity Tertiarybutylphosphine

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    Large scale manufacture of phosphide based semiconductor devices by organo-metallic vapor phase epitaxy (OMVPE) typically requires the use of highly toxic phosphine. Advancements in phosphine substitutes have identified tertiarybutylphosphine (TBP) as an excellent precursor for OMVPE of InP. High quality undoped and doped InP films were grown using TBP and trimethylindium. Impurity doped InP films were achieved utilizing diethylzinc and silane for p and n type respectively. 16 percent efficient solar cells under air mass zero, one sun intensity were demonstrated with Voc of 871 mV and fill factor of 82.6 percent. It was shown that TBP could replace phosphine, without adversely affecting device quality, in OMVPE deposition of InP thus significantly reducing toxic gas exposure risk

    Clinical yield of diagnostic endoscopic retrograde cholangiopancreatography in orthotopic liver transplant recipients With suspected biliary complications

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    Diagnostic endoscopic retrograde cholangiopancreatography (D‐ERCP) is commonly performed for the evaluation of biliary complications after orthotopic liver transplantation (OLT). This practice is contrary to the national trend of reserving endoscopic retrograde cholangiopancreatography (ERCP) for therapeutic purposes. Our aim was to evaluate the clinical yield and complications of D‐ERCP in OLT recipients. In this retrospective study, 165 OLT recipients who underwent ERCP between January 2006 and December 2010 at the University of Michigan were divided into 2 groups: (1) a therapeutic endoscopic retrograde cholangiopancreatography (T‐ERCP) group (if they met prespecified criteria that suggested a high likelihood of endoscopic intervention) and (2) a D‐ERCP group (if there was clinical suspicion of biliary disease but they did not meet any criteria). The 2 groups were compared with respect to the proportion of subjects undergoing high‐yield ERCP, which was defined as a procedure resulting in a clinically important intervention that modified the disease course. 66.3% of the D‐ERCP procedures were classified as high‐yield, whereas 90.1% of the T‐ERCP procedures were ( P < 0.001). Serious complications were infrequent in both groups. A survey of practitioners caring for OLT recipients suggested that the rate of high‐yield D‐ERCP seen in this study is congruent with what is considered acceptable in clinical practice. In conclusion, although T‐ERCP is more likely to reveal a pathological process requiring an intervention, D‐ERCP appears to be an acceptable clinical strategy for OLT recipients because of the high likelihood of a high‐yield study and the low rate of serious complications. Liver Transpl, 2012. © 2012 AASLD.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95170/1/23535_ftp.pd

    InGaAs PV device development for TPV power systems

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    Indium gallium arsenide (InGaAs) photovoltaic devices have been fabricated with bandgaps ranging from 0.75 eV to 0.60 on Indium phosphide (InP) substrates. Reported efficiencies have been as high as 11.2 percent (AMO) for the lattice matched 0.75 eV devices. The 0.75 eV cell demonstrated 14.8 percent efficiency under a 1500 K blackbody with a projected efficiency of 29.3 percent. The lattice mismatched devices (0.66 and 0.60 eV) demonstrated measured efficiencies of 8 percent and 6 percent respectively under similar conditions. Low long wavelength response and high rack currents are responsible for the poor performance of the mismatched devices. Temperature coefficients have been measured and are presented for all of the bandgaps tested

    From Bench Top to Market: Growth of Multi-Walled Carbon Nanotubes by Injection CVD Using Fe Organometallics - Production of a Commercial Reactor

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    Preferential oriented multiwalled carbon nanotubes were prepared by the injection chemical vapor deposition (CVD) method using either cyclopentadienyliron dicarbonyl dimer or cyclooctatetraene iron tricarbonyl as the iron catalyst source. The catalyst precursors were dissolved in toluene as the carrier solvent for the injections. The concentration of the catalyst was found to influence both the growth (i.e., MWNT orientation) of the nanotubes, as well as the amount of iron in the deposited material. As deposited, the multiwalled carbon nanotubes contained as little as 2.8% iron by weight. The material was deposited onto tantalum foil and fused silica substrates. The nanotubes were characterized by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy and thermogravimetric analysis. This synthetic route provides a simple and scalable method to deposit MWNTs with a low defect density, low metal content and a preferred orientation. Subsequently, a small start-up was founded to commercialize the deposition equipment. The contrast between the research and entrepreneurial environments will be discussed

    Central Crosstalk for Somatic Tinnitus: Abnormal Vergence Eye Movements

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    Frequent oulomotricity problems with orthoptic testing were reported in patients with tinnitus. This study examines with objective recordings vergence eye movements in patients with somatic tinnitus patients with ability to modify their subjective tinnitus percept by various movements, such as jaw, neck, eye movements or skin pressure.Vergence eye movements were recorded with the Eyelink II video system in 15 (23–63 years) control adults and 19 (36–62 years) subjects with somatic tinnitus.1) Accuracy of divergence but not of convergence was lower in subjects with somatic tinnitus than in control subjects. 2) Vergence duration was longer and peak velocity was lower in subjects with somatic tinnitus than in control subjects. 3) The number of embedded saccades and the amplitude of saccades coinciding with the peak velocity of vergence were higher for tinnitus subjects. Yet, saccades did not increase peak velocity of vergence for tinnitus subjects, but they did so for controls. 4) In contrast, there was no significant difference of vergence latency between these two groups.The results suggest dysfunction of vergence areas involving cortical-brainstem-cerebellar circuits. We hypothesize that central auditory dysfunction related to tinnitus percept could trigger mild cerebellar-brainstem dysfunction or that tinnitus and vergence dysfunction could both be manifestations of mild cortical-brainstem-cerebellar syndrome reflecting abnormal cross-modality interactions between vergence eye movements and auditory signals

    Reappraisal of non-invasive management strategies for uninvestigated dyspepsia: a cost-minimization analysis

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    Background : The benefits of the Helicobacter pylori test-and-treat strategy are attributable largely to the cure of peptic ulcer disease while limiting the use of endoscopy. Aim : To reappraise the test-and-treat strategy and empirical proton pump inhibitor therapy for the management of uninvestigated dyspepsia in the light of the decreasing prevalence of H. pylori infection, peptic ulcer disease and peptic ulcer disease attributable to H. pylori . Methods : Using a decision analytical model, we estimated the cost per patient with uninvestigated dyspepsia managed with the test-and-treat strategy (25/test;H.pyloritreatment,25/test; H.pylori treatment, 200) or proton pump inhibitor (90/month).Endoscopy(90/month). Endoscopy (550) guided therapy for persistent or recurrent symptoms. Results : In the base case (25% H. pylori prevalence, 20% likelihood of peptic ulcer disease, 75% of ulcers due to H.pylori ), the cost per patient is 545withthetestandtreatstrategyand545 with the test-and-treat strategy and 529 with proton pump inhibitor, and both strategies yield similar clinical outcomes at 1 year. H. pylori prevalence, the likelihood of peptic ulcer disease and the proportion of ulcers due to H.pylori are important determinants of the least costly strategy. At an H. pylori prevalence below 20%, proton pump inhibitor is consistently less costly than the test-and-treat strategy. Conclusions : As the H. pylori prevalence, the likelihood of peptic ulcer disease and the proportion of ulcers due to H. pylori decrease, empirical proton pump inhibitor becomes less costly than the test-and-treat strategy for the management of uninvestigated dyspepsia. Given the modest cost differential between the strategies, the test-and-treat strategy may be favoured if patients without peptic ulcer disease derive long-term benefit from H.pylori eradication.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75747/1/j.1365-2036.2002.01306.x.pd

    Regional and racial variations in the utilization of endoscopic retrograde cholangiopancreatography among pancreatic cancer patients in the United States

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    BackgroundPancreatic cancer is projected to become the second leading cause of cancerâ related deaths by 2030. Endoscopic retrograde cholangiopancreatography (ERCP) is recommended as firstâ line therapy for biliary decompression in pancreatic cancer. The aim of our study was to characterize geographic and racial/ethnic disparities in ERCP utilization among patients with pancreatic cancer.MethodsRetrospective cohort study using the US Surveillance, Epidemiology, and End Results (SEER)â Medicare database to identify patients diagnosed with pancreatic cancer from 2003â 2013. The primary outcome was receipt of ERCP, with or without stent placement, vs any nonâ ERCP biliary intervention.ResultsOf the 36 619 patients with pancreatic cancer, 37.5% (n = 13 719) underwent an ERCP, percutaneous drainage, or surgical biliary bypass. The most common biliary intervention (82.6%) was ERCP. After adjusting for tumor location and stage, Blacks were significantly less likely to receive ERCP than Whites (aOR 0.84, 95% CI 0.72, 0.97) and more likely to receive percutaneous transhepatic biliary drainage (PTBD) (aOR 1.38, 95% CI 1.14, 1.66). Patients in the Southeast and the West were more likely to receive ERCP than those in the Northeast (Southeast aOR 1.21, 95% CI 1.04, 1.40; West aOR 1.16, 95% CI 1.01, 1.32).ConclusionRacial/ethnic and geographic disparities in access to biliary interventions including ERCP exist for patients with pancreatic cancer in the United States. Our results highlight the need for further research and policies to improve access to appropriate biliary intervention for all patients.To date, disparities in the receipt of endoscopic therapies among patients with pancreatic cancer have not been reported. The results from our study suggest that blacks with pancreatic cancer and patients in the Northeast region of the US are less likely to receive the gold standard therapy for obstructive jaundice.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149758/1/cam42225_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149758/2/cam42225.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149758/3/cam42225-sup-0001-Supinfo.pd

    Childhood febrile illness and the risk of myopia in UK Biobank participants

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    Purpose Historical reports suggest febrile illness during childhood is a risk factor for myopia. The establishment of the UK Biobank provided a unique opportunity to investigate this relationship. Patients and methods We studied a sample of UK Biobank participants of White ethnicity aged 40–69 years old who underwent autorefraction (N=91 592) and were classified as myopic (≤−0.75 Dioptres (D)), highly myopic (≤−6.00 D), or non-myopic (>−0.75 D). Self-reported age at diagnosis of past medical conditions was ascertained during an interview with a nurse at a Biobank assessment centre. Logistic regression analysis was used to calculate the odds ratio (OR) for myopia or high myopia associated with a diagnosis before age 17 years of each of nine febrile illnesses, after adjusting for potential confounders (age, sex, highest educational qualification, and birth order). Results Rubella, mumps, and pertussis were associated with myopia: rubella, OR=1.38, 95% CI: 1.03–1.85, P=0.030; mumps, OR=1.32, 95% CI: 1.07–1.64, P=0.010; and pertussis, OR=1.39, 95% CI 1.03–1.87, P=0.029. Measles, rubella, and pertussis were associated with high myopia: measles, OR=1.48, 95% CI: 1.07–2.07, P=0.019; rubella, OR=1.94, 95% CI: 1.12–3.35, P=0.017; and pertussis, OR=2.15, 95% CI: 1.24–3.71, P=0.006. The evidence did not support an interaction between education and febrile illness in explaining the above risks. Conclusion A history of childhood measles, rubella, or pertussis was associated with high myopia, whereas a history of childhood rubella, mumps, or pertussis was associated with any myopia. The reasons for these associations are unclear
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