Transmission through the band-gap states in Schottky-barrier carbon nanotube transistors

We have studied the minimum off-state leakage current of ultrascaled Schottky-barrier carbon nanotube transistors (SBCNTs) with midgap Schottky-barrier source/drain contacts. The off-state leakage current is separated into two parts: thermal emission around the top of the Schottky barrier and tunneling through the evanescent band-gap states. Because the transmission through deep band-gap states makes a dominant contribution for ultrascaled SBCNTs, the off-state minimum leakage current increases exponentially with decreasing scaling length of SBCNTs.     

Note: Compact high voltage pulse transformer made using a capacitor bank assembled in the shape of primary

The experimental results of an air-core pulse transformer are presented, which is very compact (<10 Kg in weight) and is primed by a capacitor bank that is fabricated in such a way that the capacitor bank with its switch takes the shape of single-turn rectangular shaped primary of the transformer. A high voltage capacitor assembly (pulse-forming-line capacitor, PFL) of 5.1 nF is connected with the secondary of transformer. The transformer output voltage is 160 kV in its second peak appearing in less than 2 μS from the beginning of the capacitor discharge. The primary capacitor bank can be charged up to a maximum of 18 kV, with the voltage delivery of 360 kV in similar capacitive loads.     

Microstructure and steady state creep in Ti-24Al-11Nb

The steady state creep behaviour of the two-phase Ti₃Al-based alloy, Ti-24Al-11Nb, has been examined as a function of microstructure at temperatures ranging from 798 to 998 K and stress levels ranging from 30 to 400 MPa. Three microstructural conditions corresponding to 90% equiaxed ₂, 40% equiaxed ₂, and 100% lath ₂ structures have been studied. A low-stress Coble creep regime has been identified, with the lath ₂ structure showing the greates creep resistance in this regime. The lath ₂ structure is also stronger in the dislocation creep regime. The creep strength of this ordered alloy is shown to derive from frequency factors for diffusion, which are about two to three orders of magnitude lower than those for disordered alloys. Activation energies for creep in both the diffusional and dislocation creep domains are similar to values obtained in disordered alloys.     

In situ nitridation of titanium–molybdenum alloys during laser deposition

In situ nitridation during laser deposition of titanium–molybdenum alloys from elemental powder blends has been achieved by introducing the reactive nitrogen gas during the deposition process. Thus, Ti–Mo–N alloys have been deposited using the laser engineered net shaping (LENS^TM) process and resulted in the formation of a hard α(Ti,N) phase, exhibiting a dendritic morphology, distributed within a β(Ti–Mo) matrix with fine scale transformed α precipitates. Varying the composition of the Ar + N₂ gas employed during laser deposition permits a systematic increase in the nitrogen content of the as-deposited Ti–Mo–N alloy. Interestingly, the addition of nitrogen, which stabilizes the α phase in Ti, changes the solidification pathway and the consequent sequence of phase evolution in these alloys. The nitrogen-enriched hcp α(Ti,N) phase has higher c/a ratio, exhibits an equiaxed morphology, and tends to form in clusters separated by ribs of the Mo-rich β phase. The Ti–Mo–N alloys also exhibit a substantial enhancement in microhardness due to the formation of this α(Ti,N) phase, combining it with the desirable properties of the β-Ti matrix, such as excellent ductility, toughness, and formability.     

Development of a Mortality Prediction Model in Hospitalised SARS-CoV-2 Positive Patients Based on Routine Kidney Biomarkers

Acute kidney injury (AKI) is a prevalent complication in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) positive inpatients, which is linked to an increased mortality rate compared to patients without AKI. Here we analysed the difference in kidney blood biomarkers in SARS-CoV-2 positive patients with non-fatal or fatal outcome, in order to develop a mortality prediction model for hospitalised SARS-CoV-2 positive patients. A retrospective cohort study including data from suspected SARS-CoV-2 positive patients admitted to a large National Health Service (NHS) Foundation Trust hospital in the Yorkshire and Humber regions, United Kingdom, between 1 March 2020 and 30 August 2020. Hospitalised adult patients (aged ≥ 18 years) with at least one confirmed positive RT-PCR test for SARS-CoV-2 and blood tests of kidney biomarkers within 36 h of the RT-PCR test were included. The main outcome measure was 90-day in-hospital mortality in SARS-CoV-2 infected patients. The logistic regression and random forest (RF) models incorporated six predictors including three routine kidney function tests (sodium, urea; creatinine only in RF), along with age, sex, and ethnicity. The mortality prediction performance of the logistic regression model achieved an area under receiver operating characteristic (AUROC) curve of 0.772 in the test dataset (95% CI: 0.694–0.823), while the RF model attained the AUROC of 0.820 in the same test cohort (95% CI: 0.740–0.870). The resulting validated prediction model is the first to focus on kidney biomarkers specifically on in-hospital mortality over a 90-day period.     

Some principles for designing a wide-area WDM optical network

We explore design principles for next-generation optical wide-area networks, employing wavelength-division multiplexing (WDM) and targeted to nationwide coverage. This optical network exploits wavelength multiplexers and optical switches in routing nodes, so that an arbitrary virtual topology may be embedded on a given physical fiber network. The virtual topology, which is used as a packet-switched network and which consists of a set of all-optical “lightpaths”, is set up to exploit the relative strengths of both optics and electronics-viz. packets of information are carried by the virtual topology “as far as possible” in the optical domain, but packet forwarding from lightpath to lightpath is performed via electronic switching, whenever required. We formulate the virtual topology design problem as an optimization problem with one of two possible objective functions: (1) for a given traffic matrix, minimize the network-wide average packet delay (corresponding to a solution for present traffic demands), or (2) maximize the scale factor by which the traffic matrix can be scaled up (to provide the maximum capacity upgrade for future traffic demands). Since simpler versions of this problem have been shown to be NP-hard, we resort to heuristic approaches. Specifically, we employ an iterative approach which combines “simulated annealing” (to search for a good virtual topology) and “flow deviation” (to optimally route the traffic-and possibly bifurcate its components-on the virtual topology). We do not consider the number of available wavelengths to be a constraint, i.e., we ignore the routing of lightpaths and wavelength assignment for these lightpaths. We illustrate our approaches by employing experimental traffic statistics collected from NSFNET     

CX3CL1 Action on Microglia Protects from Diet-Induced Obesity by Restoring POMC Neuronal Excitability and Melanocortin System Activity Impaired by High-Fat Diet Feeding

Both hypothalamic microglial inflammation and melanocortin pathway dysfunction contribute to diet-induced obesity (DIO) pathogenesis. Previous studies involving models of altered microglial signaling demonstrate altered DIO susceptibility with corresponding POMC neuron cytological changes, suggesting a link between microglia and the melanocortin system. We addressed this hypothesis using the specific microglial silencing molecule, CX3CL1 (fractalkine), to determine whether reducing hypothalamic microglial activation can restore POMC/melanocortin signaling to protect against DIO. We performed metabolic analyses in high fat diet (HFD)-fed mice with targeted viral overexpression of CX3CL1 in the hypothalamus. Electrophysiologic recording in hypothalamic slices from POMC-MAPT-GFP mice was used to determine the effects of HFD feeding and microglial silencing via minocycline or CX3CL1 on GFP-labeled POMC neurons. Finally, mice with hypothalamic overexpression of CX3CL1 received central treatment with the melanocortin receptor antagonist SHU9119 to determine whether melanocortin signaling is required for the metabolic benefits of CX3CL1. Hypothalamic overexpression of CX3CL1 increased leptin sensitivity and POMC gene expression, while reducing weight gain in animals fed an HFD. In electrophysiological recordings from hypothalamic slice preparations, HFD feeding was associated with reduced POMC neuron excitability and increased amplitude of inhibitory postsynaptic currents. Microglial silencing using minocycline or CX3CL1 treatment reversed these HFD-induced changes in POMC neuron electrophysiologic properties. Correspondingly, blockade of melanocortin receptor signaling in vivo prevented both the acute and chronic reduction in food intake and body weight mediated by CX3CL1. Our results show that suppressing microglial activation during HFD feeding reduces DIO susceptibility via a mechanism involving increased POMC neuron excitability and melanocortin signaling.     

Landcover classification in MRF context using Dempster-Shafer fusion for multisensor imagery.

This work deals with multisensor data fusion to obtain landcover classification. The role of feature-level fusion using the Dempster-Shafer rule and that of data-level fusion in the MRF context is studied in this paper to obtain an optimally segmented image. Subsequently, segments are validated and classification accuracy for the test data is evaluated. Two examples of data fusion of optical images and a synthetic aperture radar image are presented, each set having been acquired on different dates. Classification accuracies of the technique proposed are compared with those of some recent techniques in literature for the same image data.     

Novel defects in Al–Pd–Fe complex metallic alloys: A micromechanical modelling approach

Transmission electron microscopy investigations have revealed that in the face centred complex metallic alloy of C₂–Al–Pd–Fe, the dislocations mediating plastic flow are decorated by localized regions of body centred structure in the compressive part of their strain field thus forming composite defects. We calculated the properties of these defects using a micromechanical model. The Eshelby method was employed to estimate the energies involved in the formation of such defects in the face-centred C₂ phase. We could reproduce the experimentally observed features of the defects in terms of their size and spatial configuration. The model describes a unique mechanism of a non-equilibrium defect, i.e., a dislocation, being stabilized by the formation and interaction with another non-equilibrium defect, i.e., a nanometre sized inclusion of different structure.     

Dynamic stiffness elements and their applications for plates using first order shear deformation theory

Dynamic stiffness elements for plates are developed using first order shear deformation theory to carry out exact free vibration analysis of plate assemblies. The analysis has been facilitated by the application of Hamiltonian mechanics and symbolic computation. The Wittrick–Williams algorithm has been used as the solution technique. Results have been extensively validated using published literature for both uniform and non-uniform plates. Some finite element results are also provided. The accuracy and computational efficiency of the method are demonstrated. In the final part of the investigation, significant plate parameters are varied and their subsequent effects on the free vibration characteristics are studied.