514 research outputs found
Long wavelength infrared detector
Long wavelength infrared detection is achieved by a detector made with layers of quantum well material bounded on each side by barrier material to form paired quantum wells, each quantum well having a single energy level. The width and depth of the paired quantum wells, and the spacing therebetween, are selected to split the single energy level with an upper energy level near the top of the energy wells. The spacing is selected for splitting the single energy level into two energy levels with a difference between levels sufficiently small for detection of infrared radiation of a desired wavelength
Passivation of high temperature superconductors
The surface of high temperature superconductors such as YBa2Cu3O(7-x) are passivated by reacting the native Y, Ba and Cu metal ions with an anion such as sulfate or oxalate to form a surface film that is impervious to water and has a solubility in water of no more than 10(exp -3) M. The passivating treatment is preferably conducted by immersing the surface in dilute aqueous acid solution since more soluble species dissolve into the solution. The treatment does not degrade the superconducting properties of the bulk material
Nanowire Growth for Sensor Arrays
A design concept for nanowire-based sensors and arrays is described. The
fabrication technique involves electrodeposition to directly grow nanowires
between patterned thin film contact electrodes. To prove our concept, we have
electrodeposited 1-mm diameter Pd single wires and small arrays. To demonstrate
nanowire sensors, we have electrochemically grown metal (Pd, Au, Pt), metal
oxide (Sb2O3), and conducting polymer (polyaniline) bundled nanowires. Using Pt
bundled nanowires surface modified with glucose oxidase, we have demonstrated
glucose detection as a demonstration of a biomolecular sensor.Comment: To appear in Nanofabrication Technologies, Ed. E. A. Dobisz, SPIE
Proceedings 5220, pp. xxx (2003, in press
Epitaxial heterojunctions of oxide semiconductors and metals on high temperature superconductors
Epitaxial heterojunctions formed between high temperature superconductors and metallic or semiconducting oxide barrier layers are provided. Metallic perovskites such as LaTiO3, CaVO3, and SrVO3 are grown on electron-type high temperature superconductors such as Nd(1.85)Ce(0.15)CuO(4-x). Alternatively, transition metal bronzes of the form A(x)MO(3) are epitaxially grown on electron-type high temperature superconductors. Also, semiconducting oxides of perovskite-related crystal structures such as WO3 are grown on either hole-type or electron-type high temperature superconductors
Method to Improve Indium Bump Bonding via Indium Oxide Removal Using a Multi-Step Plasma Process
A process for removing indium oxide from indium bumps in a flip-chip structure to reduce contact resistance, by a multi-step plasma treatment. A first plasma treatment of the indium bumps with an argon, methane and hydrogen plasma reduces indium oxide, and a second plasma treatment with an argon and hydrogen plasma removes residual organics. The multi-step plasma process for removing indium oxide from the indium bumps is more effective in reducing the oxide, and yet does not require the use of halogens, does not change the bump morphology, does not attack the bond pad material or under-bump metallization layers, and creates no new mechanisms for open circuits
Two-Step Plasma Process for Cleaning Indium Bonding Bumps
A two-step plasma process has been developed as a means of removing surface oxide layers from indium bumps used in flip-chip hybridization (bump bonding) of integrated circuits. The two-step plasma process makes it possible to remove surface indium oxide, without incurring the adverse effects of the acid etching process
Microfabrication of silicon–nitride micromesh bolometric detectors for Planck high frequency instrument
The high frequency instrument (HFI) on the National Aeronautics and Space Administration/European Space Agency Planck Surveyor, scheduled for launch in 2007, will map the entire sky in six frequency bands ranging from 100 to 857 GHz to probe cosmic microwave background anisotropy and polarization with angular resolution ranging from 9[prime] to 5[prime]. The HFI focal plane will contain 48 silicon–nitride micromesh bolometers operating from a 100 mK heat sink. Four detectors in each of the six bands will detect unpolarized radiation. An additional four pairs of detectors will provide sensitivity to linear polarization of emissions at 143, 217, and 353 GHz. We have fabricated and developed sensitive Si3N4 micromesh spider-web bolometers for submillimeter observation using microelectromechanical system techniques. The spiderweb architecture in this research provides high infrared absorption with minimal heat capacity and volume
No evidence for association between tau gene haplotypic variants and susceptibility to Creutzfeldt-Jakob disease
Contains fulltext :
52965.pdf ( ) (Open Access)BACKGROUND: A polymorphism at codon 129 of the prion protein gene (PRNP) is the only well-known genetic risk factor for Creutzfeldt-Jakob disease (CJD). However, there is increasing evidence that other loci outside the PRNP open reading frame might play a role in CJD aetiology as well. METHODS: We studied tau protein gene (MAPT) haplotypic variations in a population of sporadic and variant CJD patients. We tested 6 MAPT haplotype tagging SNPs (htSNPs) in a Dutch population-based sample of sporadic CJD (sCJD) patients and a cognitively normal control group of similar age distribution. We genotyped the same polymorphisms in two other sample groups of sCJD cases from Italy and the UK. In addition, we compared MAPT haplotypes between sCJD and variant CJD (vCJD) patients. RESULTS: Single locus and haplotype analyses did not detect any significant difference between sCJD cases and controls. When we compared MAPT haplotypes between sCJD and variant CJD (vCJD) patients, we found that two of them were represented differently (H1f: 8% in sCJD versus 2% in vCJD; H1j:1% in sCJD versus 7% in vCJD). However, these two haplotypes were rare in both groups of patients, and taking the small sample sizes into account, we cannot exclude that the differences are due to chance. None of the p-values remained statistically significant after applying a multiple testing correction. CONCLUSION: Our study shows no evidence for an association between MAPT gene variations and sCJD, and some weak evidence for an association to vCJD
Measurement of the cosmic ray spectrum above eV using inclined events detected with the Pierre Auger Observatory
A measurement of the cosmic-ray spectrum for energies exceeding
eV is presented, which is based on the analysis of showers
with zenith angles greater than detected with the Pierre Auger
Observatory between 1 January 2004 and 31 December 2013. The measured spectrum
confirms a flux suppression at the highest energies. Above
eV, the "ankle", the flux can be described by a power law with
index followed by
a smooth suppression region. For the energy () at which the
spectral flux has fallen to one-half of its extrapolated value in the absence
of suppression, we find
eV.Comment: Replaced with published version. Added journal reference and DO
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