347 research outputs found
XPS Analysis of AuGeNi/Cleaved GaAs(110) Interface
The depth composition of the thin layer alloy, AuGeNi, devoted to acting as an ohmic contact on n-GaAs(110) has been investigated by in situ XPS combined with Argon ion sputtering techniques. The fresh cleaved surfaces, supposed to be free of oxygen, were usually deposited with a 200 nm metallic layer in high vacuum conditions (better than 10−7 torr), by thermal evaporation, and annealed at a 430–450° Celsius temperature for 5 minutes. About 18 sessions of ion Ar surfaces etching and intermediate XPS measurements were performed in order to reveal the border of the metal/semiconductor interface. The atomic concentrations of the chemical elements have been approximated. Au4f, Ga3d, Ga2p, As3d, As2p, Ni2p3/2, Ge3d, O1s, and C1s spectral lines were recorded. The Au, Ge, and Ni have a homogenous distribution while Ga and As tend to diffuse to the surface. Oxygen is present in the first layers of the surface while carbon completely disappears after the second etching step. The existence of an Au-Ga alloy was detected and XPS spectra show only metal Ni and Ge within the layer and at the interface. We tried to perform a study about the depth chemical composition profile analysis of AuGeNi layer on cleaved n-GaAs(110) by X-Ray Photoelectron Spectroscopy (XPS) technique
The Small Whiskbroom Imager for atmospheric compositioN monitorinG (SWING) and its operations from an unmanned aerial vehicle (UAV) during the AROMAT campaign
The Small Whiskbroom Imager for atmospheric compositioN monitorinG (SWING) is a compact remote sensing instrument dedicated to mapping trace gases from an unmanned aerial vehicle (UAV). SWING is based on a compact visible spectrometer and a scanning mirror to collect scattered sunlight. Its weight, size, and power consumption are respectively 920g, 27cm × 12cm × 8cm, and 6W. SWING was developed in parallel with a 2.5m flying-wing UAV. This unmanned aircraft is electrically powered, has a typical airspeed of 100km h−1, and can operate at a maximum altitude of 3km.
We present SWING-UAV experiments performed in Romania on 11 September 2014 during the Airborne ROmanian Measurements of Aerosols and Trace gases (AROMAT) campaign, which was dedicated to test newly developed instruments in the context of air quality satellite validation. The UAV was operated up to 700m above ground, in the vicinity of the large power plant of Turceni (44.67°N, 23.41°E; 116m a. s. l. ). These SWING-UAV flights were coincident with another airborne experiment using the Airborne imaging differential optical absorption spectroscopy (DOAS) instrument for Measurements of Atmospheric Pollution (AirMAP), and with ground-based DOAS, lidar, and balloon-borne in situ observations.
The spectra recorded during the SWING-UAV flights are analysed with the DOAS technique. This analysis reveals NO2 differential slant column densities (DSCDs) up to 13±0.6×1016molec cm−2. These NO2 DSCDs are converted to vertical column densities (VCDs) by estimating air mass factors. The resulting NO2 VCDs are up to 4.7±0.4×1016molec cm−2. The water vapour DSCD measurements, up to 8±0.15×1022molec cm−2, are used to estimate a volume mixing ratio of water vapour in the boundary layer of 0.013±0.002mol mol−1. These geophysical quantities are validated with the coincident measurements
Generation of Radiology Findings in Chest X-Ray by Leveraging Collaborative Knowledge
Among all the sub-sections in a typical radiology report, the Clinical
Indications, Findings, and Impression often reflect important details about the
health status of a patient. The information included in Impression is also
often covered in Findings. While Findings and Impression can be deduced by
inspecting the image, Clinical Indications often require additional context.
The cognitive task of interpreting medical images remains the most critical and
often time-consuming step in the radiology workflow. Instead of generating an
end-to-end radiology report, in this paper, we focus on generating the Findings
from automated interpretation of medical images, specifically chest X-rays
(CXRs). Thus, this work focuses on reducing the workload of radiologists who
spend most of their time either writing or narrating the Findings. Unlike past
research, which addresses radiology report generation as a single-step image
captioning task, we have further taken into consideration the complexity of
interpreting CXR images and propose a two-step approach: (a) detecting the
regions with abnormalities in the image, and (b) generating relevant text for
regions with abnormalities by employing a generative large language model
(LLM). This two-step approach introduces a layer of interpretability and aligns
the framework with the systematic reasoning that radiologists use when
reviewing a CXR.Comment: Information Technology and Quantitative Management (ITQM 2023
Enhanced laser thermal ablation for the in vitro treatment of liver cancer by specific delivery of multiwalled carbon nanotubes functionalized with human serum albumin
The main goal of this investigation was to develop and test a new method of treatment for human hepatocellular carcinoma (HCC). We present a method of carbon nanotube-enhanced laser thermal ablation of HepG2 cells (human hepatocellular liver carcinoma cell line) based on a simple multiwalled carbon nanotube (MWCNT) carrier system, such as human serum albumin (HSA), and demonstrate its selective therapeutic efficacy compared with normal hepatocyte cells. Both HepG2 cells and hepatocytes were treated with HSA–MWCNTs at various concentrations and at various incubation times and further irradiated using a 2 W, 808 nm laser beam. Transmission electron, phase contrast, and confocal microscopy combined with immunochemical staining were used to demonstrate the selective internalization of HSA–MWCNTs via Gp60 receptors and the caveolin-mediated endocytosis inside HepG2 cells. The postirradiation apoptotic rate of HepG2 cells treated with HSA–MWCNTs ranged from 88.24% (for 50 mg/L) at 60 sec to 92.34% (for 50 mg/L) at 30 min. Significantly lower necrotic rates were obtained when human hepatocytes were treated with HSA–MWCNTs in a similar manner. Our results clearly show that HSA–MWCNTs selectively attach on the albondin (aka Gp60) receptor located on the HepG2 membrane, followed by an uptake through a caveolin-dependent endocytosis process. These unique results may represent a major step in liver cancer treatment using nanolocalized thermal ablation by laser heating
Selective ex-vivo photothermal ablation of human pancreatic cancer with albumin functionalized multiwalled carbon nanotubes
The process of laser-mediated ablation of cancer cells marked with
biofunctionalized carbon nanotubes is frequently called
“nanophotothermolysis”. We herein present a method of selective
nanophotothermolisys of pancreatic cancer (PC) using multiwalled carbon
nanotubes (MWCNTs) functionalized with human serum albumin (HSA). With the
purpose of testing the therapeutic value of these nanobioconjugates, we have
developed an ex-vivo experimental platform. Surgically resected specimens from
patients with PC were preserved in a cold medium and kept alive via
intra-arterial perfusion. Additionally, the HSA-MWCNTs have been
intra-arterially administered in the greater pancreatic artery under ultrasound
guidance. Confocal and transmission electron microscopy combined with
immunohistochemical staining have confirmed the selective accumulation of
HSA-MWCNTs inside the human PC tissue. The external laser irradiation of the
specimen has significantly produced extensive necrosis of the malign tissue
after the intra-arterial administration of HSA-MWCNTs, without any harmful
effects on the surrounding healthy parenchyma. We have obtained a selective
photothermal ablation of the malign tissue based on the selective
internalization of MWCNTs with HSA cargo inside the pancreatic adenocarcinoma
after the ex-vivo intra-arterial perfusion
Terrestrial Very-Long-Baseline Atom Interferometry:Workshop Summary
This document presents a summary of the 2023 Terrestrial Very-Long-Baseline Atom Interferometry Workshop hosted by CERN. The workshop brought together experts from around the world to discuss the exciting developments in large-scale atom interferometer (AI) prototypes and their potential for detecting ultralight dark matter and gravitational waves. The primary objective of the workshop was to lay the groundwork for an international TVLBAI proto-collaboration. This collaboration aims to unite researchers from different institutions to strategize and secure funding for terrestrial large-scale AI projects. The ultimate goal is to create a roadmap detailing the design and technology choices for one or more km-scale detectors, which will be operational in the mid-2030s. The key sections of this report present the physics case and technical challenges, together with a comprehensive overview of the discussions at the workshop together with the main conclusions
Towards Terahertz Sensing Based on Precision Measurements of the AC-Stark Effect with Cold Trapped HD + Ions
International audienc
Phase-Sensitive Vector Terahertz Electrometry from Precision Spectroscopy of Molecular Ions
This article proposes a new method for sensing THz waves that can allow electric field measurements traceable to the International System of Units and to the fundamental physical constants by using the comparison between precision measurements with cold trapped HD+ ions and accurate predictions of molecular ion theory. The approach exploits the lightshifts induced on the two-photon rovibrational transition at 55.9 THz by a THz wave around 1.3 THz, which is off-resonantly coupled to the HD+ fundamental rotational transition. First, the direction and the magnitude of the static magnetic field applied to the ion trap is calibrated using Zeeman spectroscopy of HD+. Then, a set of lightshifts are converted into the amplitudes and the phases of the THz electric field components in an orthogonal laboratory frame by exploiting the sensitivity of the lightshifts to the intensity, the polarization and the detuning of the THz wave to the HD+ energy levels. The THz electric field measurement uncertainties are estimated for quantum projection noise-limited molecular ion frequency measurements with the current accuracy of molecular ion theory. The method has the potential to improve the sensitivity and accuracy of electric field metrology and may be extended to THz magnetic fields and to optical fields
THz/Infrared Double Resonance Two-Photon Spectroscopy of HD+ for Determination of Fundamental Constants
A double resonance two-photon spectroscopy scheme is discussed to probe jointly rotational and rovibrational transitions of ensembles of trapped HD+ ions. The two-photon transition rates and lightshifts are calculated with the two-photon tensor operator formalism. The rotational lines may be observed with sub-Doppler linewidth at the hertz level and good signal-to-noise ratio, improving the resolution in HD+ spectroscopy beyond the 10−12 level. The experimental accuracy, estimated at the 10−12 level, is comparable with the accuracy of theoretical calculations of HD+ energy levels. An adjustment of selected rotational and rovibrational HD+ lines may add clues to the proton radius puzzle, may provide an independent determination of the Rydberg constant, and may improve the values of proton-to-electron and deuteron-to-proton mass ratios beyond the 10−11 level
- …