Gap prediction in hybrid graphene - hexagonal boron nitride nanoflakes using artificial neural networks

The electronic properties graphene nanoflakes (GNFs) with embedded hexagonal boron nitride (hBN) domains are investigated by combined {\it ab initio} density functional theory calculations and machine learning techniques. The energy gaps of the quasi-0D graphene based systems, defined as the differences between LUMO and HOMO energies, depend on the sizes of the hBN domains relative to the size of the pristine graphene nanoflake, but also on the position of the hBN domain. The range of the energy gaps for different configurations is increasing as the hBN domains get larger. We develop two artificial neural network (ANN) models able to reproduce the gap energies with high accuracies and investigate the tunability of the energy gap, by considering a set of GNFs with embedded rectangular hBN domains. In one ANN model, the input is in one-to-one correspondence with the atoms in the GNF, while in the second model the inputs account for basic structures in the GNF, allowing potential use in up-scaled structures. We perform a statistical analysis over different configurations of ANNs to optimize the network structure. The trained ANNs provide a correlation between the atomic system configuration and the magnitude of the energy gaps, which may be regarded as an efficient tool for optimizing the design of nanostructured graphene based materials for specific electronic properties.Comment: 6 pages, 5 figure

MOCVD-Fabricated TiO2 Thin Films: Influence of Growth Conditions on Fibroblast Cells Culture

TiO2 thin films with various morphologies were grown on Ti substrates by the LP-MOCVD technique (Low Pressure Chemical Vapour Deposition from Metal-Organic precursor), with titanium tetra-iso-propoxide as a precursor. All the films were prepared in the same conditions except the deposition time. They were characterized by X-ray diffraction, scanning electron microscopy, optical 15 interferometry, water contact angle measurements. MOCVD-fabricated TiO2 thin films are known to be adapted to cell culture for implant requirements. Human gingival fibroblasts were cultured on the various TiO2 deposits. Differences in cell viability (MTT tests) and cell spreading (qualitative assessment) were observed and related to film roughness, wettability and allotropic composition

Hospital Acquired MRSA Penumonia

Background: Antibiotic resistance is a growing problem and particularly of concern in nosocomial infections. Nosocomial pneumonia occurs in 0.4—1.1% of hospitalized patients. It is the most common infection in intensive care units. Bacterial colonization of the upper airway followed by micro aspiration or macro inspiration into the lungs is considered the primary mechanism for development of nosocomial pneumonia. More than 90% of cases of nosocomial pneumonia are caused by bacteria, 15—30% represented with staphylococcus aureus. Following the data of a 4-year long period the resistance to methicillin was identified in ≈32% with a tendency of increasing percentage of MRSA isolates up to 35%, originated from samples taken among patients from ICU in the Clinical Center of Skopje

Improving the lens design and performance of a contemporary electromagnetic shock wave lithotripter.

The efficiency of shock wave lithotripsy (SWL), a noninvasive first-line therapy for millions of nephrolithiasis patients, has not improved substantially in the past two decades, especially in regard to stone clearance. Here, we report a new acoustic lens design for a contemporary electromagnetic (EM) shock wave lithotripter, based on recently acquired knowledge of the key lithotripter field characteristics that correlate with efficient and safe SWL. The new lens design addresses concomitantly three fundamental drawbacks in EM lithotripters, namely, narrow focal width, nonidealized pulse profile, and significant misalignment in acoustic focus and cavitation activities with the target stone at high output settings. Key design features and performance of the new lens were evaluated using model calculations and experimental measurements against the original lens under comparable acoustic pulse energy (E+) of 40 mJ. The -6-dB focal width of the new lens was enhanced from 7.4 to 11 mm at this energy level, and peak pressure (41 MPa) and maximum cavitation activity were both realigned to be within 5 mm of the lithotripter focus. Stone comminution produced by the new lens was either statistically improved or similar to that of the original lens under various in vitro test conditions and was significantly improved in vivo in a swine model (89% vs. 54%, P = 0.01), and tissue injury was minimal using a clinical treatment protocol. The general principle and associated techniques described in this work can be applied to design improvement of all EM lithotripters

Magnetic Nested-wind Scenarios for Bipolar Outflows: Pre-planetary and YSO nebular shaping

We present results of a series of magnetohydrodynamic (MHD) and hydro- dynamic (HD) 2.5D simulations of the morphology of outflows driven by nested wide-angle winds - i.e. winds which eminate from a central star as well as from an orbiting accretion disk. While our results are broadly relevent to nested wind systems we have tuned the parameters of the simulations to touch on issues in both Young Stellar Objects and Planetary Nebula studies. In particular our studies connect to open issues in the early evolution of Planetary Nebulae. We find that nested MHD winds exhibit marked morphological differences from the single MHD wind case along both dimensions of the flow. Nested HD winds on the other hand give rise mainly to geometric distortions of an outflow that is topologically similar to the flow arising from a single stellar HD wind. Our MHD results are insensitive to changes in ambient temperature between ionized and un-ionized circumstellar environments. The results are sensitive to the relative mass-loss rates, and to the relative speeds of the stellar and disk winds. We also present synthetic emission maps of both nested MHD and HD simulations. We find that nested MHD winds show knots of emission appearing on-axis that do not appear in the HD case.Comment: 28 pages, 8 figure