Ultraviolet emission of silicon quantum tips

Silicon tips used as field emitters have dimensions that are within the quantum confinement regime. Therefore they can be considered as freestanding silicon tips. In this letter, a photoluminescence spectrum of a 100×100100×100 array of silicon tips was taken at 10 K. Narrow ultraviolet luminescence peaks were observed. Using the empirical pseudopotential homojunction model, it is demonstrated that these luminescence peaks come from energy levels arising from quantum confinement. By fitting the theoretical result to the experimental result, we conclude that the luminescence peaks come from Si quantum tips of about 20 Å in width and that they are covered by silicon dioxide. © 1999 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71101/2/APPLAB-74-3-386-1.pd

Gallium vacancy and the residual acceptor in undoped GaSb studied by positron lifetime spectroscopy and photoluminescence

Positron lifetime, photoluminescence (PL), and Hall measurements were performed to study undoped p-type gallium antimonide materials. A 314 ps positron lifetime component was attributed to Ga vacancy (V Ga) related defect. Isochronal annealing studies showed at 300°C annealing, the 314 ps positron lifetime component and the two observed PL signals (777 and 797 meV) disappeared, which gave clear and strong evidence for their correlation. However, the hole concentration (∼2×10 17cm -3) was observed to be independent of the annealing temperature. Although the residual acceptor is generally related to the V Ga defect, at least for cases with annealing temperatures above 300°C, V Ga is not the acceptor responsible for the p-type conduction. © 2002 American Institute of Physics.published_or_final_versio

Influence of layer thickness to the emission spectra in microcavity organic light emitting diodes

Microcavity organic light emitting diodes (OLEDs) have attracted great attention because they can reduce the width of emission spectra from organic materials, enhance brightness and achieve multipeak emission from the same material. In this work, we have fabricated microcavity OLEDs with widely used organic materials, such as N,N'-di(naphthalene-1-yl)-N,N'-diphenylbenzidine (NPB) as a hole transport layer and tris (8-hydroxyquinoline) (Alq) as emitting and electron transporting layer. These organic materials are sandwiched either between two thick silver mirrors or one thin copper and one thick silver mirrors. The influence of total cavity length (from 164 nm to 243nm) and the cavity Q-factor to the emission behavior has been investigated. In all cases, an OLED without bottom mirror, i.e. with the organic materials sandwiched between indium tin oxide and a thick silver mirror, has been fabricated for comparison. We have characterized the devices with photoluminescence, electroluminescence, and reflectance measurements. Multiple peaks have been observed for some devices at larger viewing angles

ENGINEERING CONCEPTS IN ANALYSING LUMBOSACRAL LOAD IN POST-OPERATIVE SCOLIOTIC PATIENTS

Lumbosacral alignment plays a major role in the mechanical low back pain in normal population. Malalignment causes increased strain to the muscles and ligaments around it which eventually leads to mechanical low back pain and discomfort. The level of strain a ligament receives in the lumbosacral junction depends upon the lumbosacral angle and the load exerted on it. If there is an easy way to find the load exerted at the lumbosacral junction, then it would be trouble free for the physicians to examine. Hence, the treatment can be planned accordingly. This study analysis the angle, net force produced and stress faced by the ligaments around the lumbosacral joint in postoperative scoliosis patients using radiographic images. Study design was analytical, observational cross sectional study. Radiographs of 30 patients were collected and one sample ‘t ’test was used for data analysis with ‘p ’value set as 0.05 as level of significance .The mean lumbosacral angle of the postoperative scoliotic patients was found to be 45.56 degrees and the standard deviation was ± 8.7156. The results suggest that patients who underwent scoliosis correction surgery did not have an optimal lumbosacral angle of 30 degrees

DIPPER, a spatiotemporal proteomics atlas of human intervertebral discs for exploring ageing and degeneration dynamics

The spatiotemporal proteome of the intervertebral disc (IVD) underpins its integrity and function. We present DIPPER, a deep and comprehensive IVD proteomic resource comprising 94 genome-wide profiles from 17 individuals. To begin with, protein modules defining key directional trends spanning the lateral and anteroposterior axes were derived from high-resolution spatial proteomes of intact young cadaveric lumbar IVDs. They revealed novel region-specific profiles of regulatory activities and displayed potential paths of deconstruction in the level- and location-matched aged cadaveric discs. Machine learning methods predicted a 'hydration matrisome' that connects extracellular matrix with MRI intensity. Importantly, the static proteome used as point-references can be integrated with dynamic proteome (SILAC/degradome) and transcriptome data from multiple clinical samples, enhancing robustness and clinical relevance. The data, findings, and methodology, available on a web interface (http://www.sbms.hku.hk/dclab/DIPPER/), will be valuable references in the field of IVD biology and proteomic analytics