Electronic properties of the Sn1−xPbxO alloy and band alignment of the SnO/PbO system::a DFT study

Tin monoxide (SnO) has attracted attention due to its p-type character and capability ofambipolar conductivity when properly doped, properties that are beneficial for the realization ofcomplementary oxide thin film transistors technology, transparent flexible circuits andoptoelectronic applications in general. However, its small fundamental band gap (0.7 eV) limitsits applications as a solar energy material, therefore tuning its electronic properties is necessaryfor optimal performance. In this work, we use density functional theory (DFT) calculations toexamine the electronic properties of the Sn1-xPbxO ternary oxide system. Alloying with Pb byelement substitution increases the band gap of SnO without inducing defect states in the bandgap retaining the anti-bonding character of the valence band maximum which is beneficial for p-type conductivity. We also examine the properties of the SnO/PbO heterojunction system interms of band alignment and the effect of the most common intrinsic defects. A broken gap bandalignment for the SnO/PbO heterojunction is calculated, which can be attractive for energyconversion in solar cells, photocatalysis and hydrogen generation

Ankylosing Spondylitis in a 33- years old man with Hypermobility Joints

Background: Ankylosing spondylitis, is a chronic inflammatory autoimmune disease that mainly affects spine joints. It can cause severe, chronic pain, spine fusion and chronic disability. Ehlers-Danlos syndrome is a rare heterogenous group of hereditary connective tissue disorders which are characterized by skin hyperextensibility, joint hypermobility and tissue fragility.Case report: A 33-year old man was admitted to the Rheumatology Department of 251 Airforce General Hospital in order to decide on his capability to serve his duty as an aircraftsman at Hellenic Airforce. He was diagnosed with ankylosing spondylitis twelve years ago. On physical examination joint hypermobility and skin hyperextensibility were observed and after further investigation, he was diagnosed with hypermobility type of Ehlers Danlos Syndrome. Laboratory investigation was normal. MRI radiologic investigation revealed bony sclerosis of the left sacroiliac joint and bone marrow oedema on right sacroiliac joint. No extraskeletal manifestations were detected. The patient was informed about both conditions and he was given medical advice about their proper management. Conclusion: Rare diseases sometimes manifest as atypical inflammatory arthritis syndromes. Careful medical history, thorough physical examination and use of diagnostic criteria are useful in such patients for disease identification and treatment

Epitaxial highly ordered Sb:SnO2 nanowires grown by the vapor liquid solid mechanism on m-, r- and a-Al2O3

Epitaxial, highly ordered Sb:SnO(2) nanowires were grown by the vapor–liquid–solid mechanism on m-, r- and a-Al(2)O(3) between 700 °C and 1000 °C using metallic Sn and Sb with a mass ratio of Sn/Sb = 0.15 ± 0.05 under a flow of Ar and O(2) at 1 ± 0.5 mbar. We find that effective doping and ordering can only be achieved inside this narrow window of growth conditions. The Sb:SnO(2) nanowires have the tetragonal rutile crystal structure and are inclined along two mutually perpendicular directions forming a rectangular mesh on m-Al(2)O(3) while those on r-Al(2)O(3) are oriented in one direction. The growth directions do not change by varying the growth temperature between 700 °C and 1000 °C but the carrier density decreased from 8 × 10(19) cm(−3) to 4 × 10(17) cm(−3) due to the re-evaporation and limited incorporation of Sb donor impurities in SnO(2). The Sb:SnO(2) nanowires on r-Al(2)O(3) had an optical transmission of 80% above 800 nm and displayed very long photoluminescence lifetimes of 0.2 ms at 300 K. We show that selective area location growth of highly ordered Sb:SnO(2) nanowires is possible by patterning the catalyst which is important for the realization of novel nanoscale devices such as nanowire solar cells

Non-linear optimal control for multi-DOF electro-hydraulic robotic manipulators

A non-linear optimal (H-infinity) control approach is proposed for the dynamic model of multi-degree-of-freedom (DOF) electro-hydraulic robotic manipulators. Control of electro-hydraulic manipulators is a non-trivial problem because of their non-linear and multi-variable dynamics. In this study, the considered robotic system consists of a multi-link robotic manipulator that receives actuation from rotary electro-hydraulic drives. The article's approach relies first on approximate linearisation of the state-space model of the electro-hydraulic manipulator, according to first-order Taylor series expansion and the computation of the related Jacobian matrices. For the approximately linearised model of the manipulator, a stabilising H-infinity feedback controller is designed. To compute the controller's gains, an algebraic Riccati equation is solved at each time-step of the control algorithm. The global stability properties of the control scheme are proven through Lyapunov analysis. The proposed control method retains the advantages of typical optimal control, i.e. fast and accurate tracking of the reference setpoints under moderate variations of the control inputs