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Microchannel Fabrication Using A Photo-Patternable Adhesive Material for Recording Conformational Changes of KcsA Channel with the Diffracted X-ray Tracking Method
摘要： Diffracted X-ray tracking (DXT) method can trace conformational changes of KcsA potassium ion channel during gating by recording position of diffraction spot from a gold nanocrystal attached to the channel as a movie. For high-resolution imaging under controlled microenvironments for KcsA channels, we report a microfluidic device consisting of two SiN membrane windows bonded with a photo patternable adhesive material. The reduced signal-to-background ratio as well as suitable adhesive material thickness for the microchannel are discussed in the experiment at the synchrotron radiation facility.
关键词： diffracted X-ray tracking method,adhesive bonding,microfluidics,KcsA ion channel
更新于2025-09-04 15:30:14
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Studies of Surface Electrical Properties of Al doped ZnO Nanorods by STM
摘要： Pure and aluminum (Al) doped ZnO (Al:ZnO) nanorods (NRs) were deposited on silicon substrates by the hydrothermal method. The Al composition was kept at 2 % and 5 % for the Al:ZnO NR samples. The surface morphology and structural properties of the pure and Al:ZnO NRs were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The XRD study revealed the hexagonal phase of the ZnO with (101), (002) and (100) peaks and it also revealed that the major orientation of ZnO NRs was along the (002) planes. The SEM micrographs showed perfectly grown ZnO NRs with hexagonal shaped tips. The electrical characterization of the pure and Al:ZnO NR thin film surface was done by scanning tunneling microscopy (STM). Local electron spectroscopy was conducted to measure the tunneling current with respect to the applied bias. The n-type behavior and bandgap of the pure and Al:ZnO NRs were confirmed from the dI/dV – V characteristics. These studies are of fundamental importance for the fabrication of pure and Al:ZnO NR based nanodevices.
关键词： X-ray diffraction,Al doped ZnO,scanning tunnelling microscopy,nanorods,hydrothermal
更新于2025-09-04 15:30:14
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Synthesis and Pholuminescence studies of polymer capped SnO2 nanoparticles synthesized by chemical co-precipitation method
摘要： In recent years many research works have been focused on the electrical and optical properties of metal oxides. In this present paper SnO2 nanoparticles have been synthesized by chemical co-precipitation method using different capping agents like EDTA (ethylene diamine tetra acetic acid), PVP (polyvinylpyrrolidone), PVA (polyvinyl alcohol) and studied the influence of capping agent on various properties of SnO2 nanoparticles. Structural, surface morphology, chemical analysis and luminescence properties of prepared SnO2 nanoparticles were studied by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) attached with energy dispersive analysis of X-rays (EDAX) and photoluminescence studies (PL). X-ray diffraction study reveals the nano-size particle distribution of the prepared samples with tetragonal rutile structure in the range of 3 to 9 nm. FTIR spectra show the structural confirmation of SnO2 nanoparticles. Various PL signals were observed in the visible region around 375 nm to 600 nm due to oxygen vacancies and interfacial Sn vacancies present in the prepared nanosamples.
关键词： X-ray diffraction,scanning electron microscopy,Nano-size distribution,Chemical co-precipitation,Photoluminescence
更新于2025-09-04 15:30:14
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A new methodology for the determination of silicon in plants by wavelength dispersive X-ray fluorescence
摘要： Silicon is an important element for plants at their structure and physiology and plays an important role in bone mineralization and soft tissue development in human beings. Furthermore, its determination is being requested more frequently due to nutritional requirements. However, the methods found in the literature to determine silicon in this type of samples require a sample preparation step, which makes them time‐consuming and provides high uncertainties. In this paper, a method for the determination of silicon in plants by wavelength dispersive X‐ray fluorescence (WD‐XRF) spectrometry has been developed. Horsetail (Equisetum arvense L.) and nettle leaf (Urtica dioica) have been used as a source of silicon due to its medical use. Sample preparation involved calcining the sample at 700°C and preparing fused beads from the calcined sample. Calibration standards for WD‐XRF measurement were prepared by mixing certified reference materials and chemical products to reproduce the samples matrix. The linear range for silicon concentration ranges from 6 to 55 wt% SiO2. The validation of the method was performed measuring a reference material (NCS DC73349 Bush branches and leaves) and comparing the results obtained by WD‐XRF with those obtained by an independent method by atomic absorption spectrometry. The developed methodology is rapid and accurate, provides low uncertainties, and is environmentally friendly, as it does require the use of less hazardous reagents.
关键词： silicon,WD‐XRF,wavelength dispersive X‐ray fluorescence,sample preparation,plants,fused beads
更新于2025-09-04 15:30:14
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[Lecture Notes in Computer Science] Understanding and Interpreting Machine Learning in Medical Image Computing Applications Volume 11038 (First International Workshops, MLCN 2018, DLF 2018, and iMIMIC 2018, Held in Conjunction with MICCAI 2018, Granada, Spain, September 16-20, 2018, Proceedings) || Vulnerability Analysis of Chest X-Ray Image Classification Against Adversarial Attacks
摘要： Recently, there have been several successful deep learning approaches for automatically classifying chest X-ray images into different disease categories. However, there is not yet a comprehensive vulnerability analysis of these models against the so-called adversarial perturbations/attacks, which makes deep models more trustful in clinical practices. In this paper, we extensively analyzed the performance of two state-of-the-art classification deep networks on chest X-ray images. These two networks were attacked by three different categories (ten methods in total) of adversarial methods (both white- and black-box), namely gradient-based, score-based, and decision-based attacks. Furthermore, we modified the pooling operations in the two classification networks to measure their sensitivities against different attacks, on the specific task of chest X-ray classification.
关键词： Chest X-ray classification,Deep learning,Adversarial perturbation
更新于2025-09-04 15:30:14
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Element- and Site-Specific Many-Body Interactions in Few-Layer MoS <sub/>2</sub> During X-Ray Absorption Processes
摘要： Few-layer MoS2 is a promising 2D material for nano-electronic device applications. However, the performance of these devices is often deteriorated. One of the reasons is that the electronic properties are influential to the many-body effects such as excitonic effects and Anderson orthogonality catastrophe (AOC) which could renormalize the band-dispersion and density-of-states(DOS). Hence, the authors investigate the effect of many-body interactions on MoS2 device performance by using X-ray absorption spectro-microscopy (m-XAS) on a few-layer MoS2 transistor in operation, through the application of gate-bias or contact with a metal. The results show a significant peak shift in m-XAS spectra while varying the gate-bias. The applied negative gate-bias induces more holes which attracts excited electrons resulting strong many-body interactions followed by Fermi level shift. This effect is discussed with the aid of XAS-Auger electron phenomena. However, the AOC contribution in XAS peak-intensity is ignored since the bands around the energy-gap in MoS2 are relatively flat and the DOS is empty above Fermi level (unlike graphene). The authors observe a redshift in photon energy near the MoS2/metal-electrode interface due to charge transfer ensuring carrier-doping induced through metal-contact. These observations provide significant insight into element- and site-specific many-body interactions in MoS2 tunable by gate-bias or contact with a metal.
关键词： many-body interactions,element- and site-specific,MoS2,X-ray absorption spectromicroscopy
更新于2025-09-04 15:30:14
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Structure, Optical, and Photocatalytic Properties of Oxynitride Solid Solutions Ca <sub/> 1- <i>x</i> </sub> Sr <i> <sub/>x</sub></i> NbO <sub/>2</sub> N, CaNb <sub/> 1- <i>x</i> </sub> Ta <i> <sub/>x</sub></i> O <sub/>2</sub> N, and SrNb <sub/> 1- <i>x</i> </sub> Ta <i> <sub/>x</sub></i> O <sub/>2</sub> N Prepared from Soft-Chemistry Precursors
摘要： Three perovskite oxynitride solid solutions Ca1–xSrxNbO2N, CaNb1–xTaxO2N, and SrNb1–xTaxO2N were prepared by low temperature ammonolysis of soft-chemistry precursors. In particular, we present for the first time a way to synthesize the substitution series Ca1–xSrxNbO2N, which cannot be prepared by ammonolysis of classical solid state precursors. All samples were phase-pure and exhibit bandgaps in the visible light range that can be tailored by substitutions both of the A- and B-type cations. Rietveld analysis was applied to determine cell parameters and crystal structures. In the case of Ca1–xSrxNbO2N a structural change from orthorhombic to tetragonal was found. After loading with CoOx the photocatalytic activities in the solution-based methyl orange degradation were investigated and for SrNb1–xTaxO2N a considerable activity was found.
关键词： Perovskites,Photocatalysis,Oxynitrides,Hydrothermal synthesis,X-ray diffraction
更新于2025-09-04 15:30:14
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A glassy carbon electrode modified with TiO2(200)-rGO hybrid nanosheets for aptamer based impedimetric determination of the prostate specific antigen
摘要： TiO2(200)-rGO hybrid nanosheets were synthesized starting from TiO2, rGO and NaOH solid powders via a scalable hydrothermal process. The weight ratio of TiO2-GO was found to be crucial on the crystal growth and biosensor properties of the final hybrid nanosheets. They were characterized by means of SEM, FESEM-EDX, XRD, XPS, Raman and FTIR spectroscopies in order to verify the formation of very thin TiO2 anatase nanosheets with an orientation of the anatase crystal structure towards the (200) plane. The free active sites of TiO2 structure and the large surface of the 2D graphene structure strongly facilitate charge transport confirmed by BET-BJH analyses. Compared to pure AuNPs, rGO and TiO2, the hybrid nanosheet modified electrode represents the most sensitive aptasensing platform for the determination of PSA. The detection was based on that the variation of electron transfer resistance (Rct) at the modified electrode surface in a solution containing 3.0 mmol L?1 [Fe(CN)6]3?/4- as a redox probe and 0.1 mol L?1 KCl as supporting electrolyte. The detection limit of the sensor is 1 pg mL?1, and the sensor can be operated up to 30 days. It was applied to the analysis of PSA levels in spiked serum samples obtained from patients with prostate cancer. Data compare well with those obtained by an immunoradiometric assay.
关键词： X-ray photoelectron spectroscopy,Effective surface area,Electrochemical impedance spectroscopy,Aptasensor,Voltammetry,Work function
更新于2025-09-04 15:30:14
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Development of Thermal Kinetic Inductance Detectors Suitable for X-ray Spectroscopy
摘要： We report on the development of thermal kinetic inductance detectors (TKIDs) suitable to perform X-ray spectroscopy measurements. The aim is to implement MKIDs sensors working in thermal quasi-equilibrium mode to detect X-ray photons as pure calorimeters. The thermal mode is a variation on the MKID classical way of operation that has generated interest in recent years. TKIDs can offer the MKIDs inherent multiplexibility in the frequency domain, a high spatial resolution comparable with CCDs, and an energy resolution theoretically limited only by thermodynamic fluctuations across the thermal weak links. Microresonators are built in Ti/TiN multilayer technology with the inductive part thermally coupled with a metal absorber on a suspended SiN membrane, to avoid escape of phonons from the film to the substrate. The mid-term goal is to optimize the single-pixel design in terms of superconducting critical temperatures, internal quality factors, kinetic inductance and spectral energy resolution. The final goal is to realize a demonstrator array for a next generation thousand pixels X-ray spectrometer. In this contribution, the status of the project after one year of developments is reported, with detailed reference to the microresonators design and simulations and to the fabrication process.
关键词： Thermal mode,Microwave kinetic inductance detectors,TKID,MKIDs,Thin film,X-ray spectroscopy,Superconducting film,Micromachining,Super-conductive microresonators,Thermal kinetic inductance detectors
更新于2025-09-04 15:30:14
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In-doped As2Se3 thin films studied by Raman and X-ray photoelectron spectroscopies
摘要： Amorphous In-doped As2Se3 films with nominal indium contents x up to 7 at. % were prepared by thermal evaporation. Atomic force microscopy studies confirm the uniform film structure with a surface roughness near 5 nm, noticeably higher than for similarly prepared undoped As2Se3 film. X-ray photoelectron spectroscopy (XPS) studies enabled the chemical composition of the films to be examined. As follows from the XPS data, the In content in the film strongly decreases with the film depth. For films with x ≥ 2 at.%, Raman features attributed to transverse and longitudinal optical phonons of InAs are revealed in the Raman spectra as an evidence for the formation of InAs nanocrystallites in the As2Se3:In film under laser illumination.
关键词： X-ray photoelectron spectroscopy,amorphous,film,Raman scattering,atomic force microscopy,semiconductor nanocrystals
更新于2025-09-04 15:30:14