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Graphene-Coated Glass Substrate for Continuous Wave Laser Desorption and Atmospheric Pressure Mass Spectrometric Imaging of Live Hippocampal Tissue
摘要： Atmospheric pressure mass spectrometric (AP-MS) imaging technology combined with an inverted optical microscopic system is a powerful tool for determining the presence and spatial distributions of specific biomolecules of interest in live tissues. Efficient desorption and ionization are essential to acquire mass spectrometric (MS) information in an ambient environment. In this study, we demonstrate a new and efficient desorption process using a graphene-coated glass substrate and a continuous wave (CW) laser for high-resolution AP-MS imaging of live hippocampal tissue. We found that desorption of biomolecules in a live tissue slice was possible with the aid of a graphene-coated glass substrate and indirect application of a 532 nm CW-laser on the graphene substrate. Interestingly, the desorption efficiency of live tissue on the graphene-coated substrate was strongly dependent on the number of graphene layers. Single-layer graphene was found to be the most sensitive substrate for efficient desorption and reproducible high-resolution hippocampal tissue imaging applications. The subsequent ionization process using nonthermal plasma generated sufficient amounts of molecular ions to obtain high-resolution 2-dimensional MS images of the cornu ammonis (CA) and the dentate gyrus (DG) regions of the hippocampus. Therefore, graphene-coated substrates could be a promising platform to induce an efficient desorption process essential for highly reproducible ambient MS imaging.
关键词： Hippocampal tissue,Mass spectrometry imaging,Laser desorption,Graphene-coated substrate,Ambient mass spectrometry
更新于2025-11-25 10:30:42
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Effect of Oxygen on Thermal and Radiation Induced Chemistries in a Model Organotin Photoresist
摘要： Organotin photoresists have shown promise for next generation lithography due to their high extreme ultraviolet (EUV) absorption cross sections, their radiation sensitive chemistries, and their ability to enable high-resolution patterning. To better understand both temperature and radiation induced reaction mechanisms, we have studied a model EUV photoresist, which consists of a charge-neutral butyl-tin cluster. Temperature programmed desorption (TPD) showed very little outgassing of the butyl-tin resist in ultrahigh vacuum, and excellent thermal stability of the butyl groups. TPD results indicated that decomposition of the butyl-tin resist was first order with a fairly constant decomposition energy between 2.4 and 3.0 eV, which was determined by butyl group desorption. Electron stimulated desorption (ESD) showed that butyl groups were the primary decomposition product for electron kinetic energies expected during EUV exposures. XPS was performed before and after low energy electron exposure to evaluate the compositional and chemical changes in the butyl-tin resists after interaction with radiation. The effect of molecular oxygen during ESD experiments was evaluated and it was found to enhance butyl group desorption during exposure, and resulted in a significant increase in the ESD cross section by over 20%. These results provide mechanistic information that can be applied to organotin EUV photoresists, where a significant increase in photoresist sensitivity may be obtained by varying the ambient conditions during EUV exposures.
关键词： X-ray photoelectron spectroscopy,electron stimulated desorption,Extreme ultraviolet lithography,organotin photoresist,temperature programmed desorption
更新于2025-09-23 15:23:52
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Dual-Route Hydrogenation of the Graphene/Ni Interface
摘要： Nanostructured architectures based on graphene/metal interfaces might be efficiently exploited in hydrogen storage due to the attractive capability to provide adsorption sites both at the top side of graphene and at the metal substrate after intercalation. We combined in situ high resolution x-ray photoelectron spectroscopy and scanning tunneling microscopy with theoretical calculations to determine the arrangement of hydrogen atoms at the graphene/Ni(111) interface at room temperature. Our results show that at low coverage H atoms predominantly adsorb as monomers and that chemisorption saturates when ～25% of the surface is hydrogenated. In parallel, with a much lower rate, H atoms intercalate below graphene and bind to Ni surface sites. Intercalation progressively destabilizes the C-H bonds and triggers the release of the hydrogen chemisorbed on graphene. Valence band and near edge absorption spectroscopy demonstrate that the graphene layer is fully lifted when the Ni surface is saturated with H. Thermal programmed desorption was used to determine the stability of the hydrogenated interface. Whereas the H atoms chemisorbed on graphene remain unperturbed over a wide temperature range, the intercalated phase abruptly desorbs 50-100 K above room temperature.
关键词： storage,graphene,intercalation,desorption,nickel,hydrogenation
更新于2025-09-23 15:23:52
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Chemical and topographical single-cell imaging by near-field desorption mass spectrometry
摘要： Simultaneous acquiring chemical and topographical information within a single cell at nanoscale resolutions is vital to cellular biology, yet it remains a great challenge for current techniques due to limited lateral resolutions and detection sensitivities. Here we report the development of near-field desorption mass spectrometry for co-registered chemical and topographical imaging, thereby bridging the gap between laser-based MS methods and multimodal single-cell imaging. Using this integrated platform, imaging resolution of 250 nm and 3D topographically reconstructed chemical single-cell imaging were achieved. This technique offers more in-depth cellular information than is currently possible with micrometre-range laser-based MS imaging methods. Considering the simplicity and compact size of the near-field device, this technique can be introduced to matrix-assisted laser desorption ionization MS, expanding the multimodal abilities of MS at nanoscale resolutions across wide disciplines.
关键词： single-cell analysis,analytical methods,multimodal imaging,mass spectrometry,near-field desorption
更新于2025-09-23 15:23:52
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The Synthesis of Mesoporous Sio2/Tio2 Composite Particles by Sol-Gel Method and Effect of Hexane on its Structural Properties
摘要： Due to their unique properties such as high surface area, uniform and adjustable pore structure, and permeability of various molecules within and on their surface, mesoporous materials have become of interest in various fields including electronics, separation, catalysis, medical applications such as implant coatings and drug delivery. Mesoporous SiO2/TiO2 particles were synthesized by sol-gel method using various amounts of surfactant cetyl tri methyl ammonium bromide (CTAB) as structure directing agent under acidic condition; moreover, hexane was applied as a swelling agent. The samples were investigated using XRD, SEM, FTIR, SEM and N2 adsorption-desorption analyses, in addition, the incremental effect of surfactant and hexane were examined. The results obtained from the analysis clarified that an increase in amount of surfactant will lead to an increase in surface area, pore size and pore volume. Additionally, with adding hexane to the constant amount of surfactant; the results showed an increase in surface area, pore size and pore volume while order of the structure was maintained.
关键词： Mesoporous,Swelling agent,N2 adsorption-desorption,Surfactant
更新于2025-09-23 15:22:29
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CoGe surface oxidation studied using X-ray photoelectron spectroscopy
摘要： Cobalt germanides have been widely studied as semiconductor contact materials, but recent theoretical studies suggest that they may also be excellent catalysts for methane steam reforming with stabilities and activities comparable to more expensive noble metal catalysts. We have sputter deposited CoGe alloy films and characterized their structure and morphology after post-deposition annealing in high vacuum up to 1000 °C. We used X-ray photoelectron spectroscopy to study the initial oxidation of amorphous and crystalline CoGe alloy surfaces under low pressures of O2 and H2O. The oxidation rate in O2 was found to be faster for an amorphous CoGe surface compared to a crystalline surface. We also found that there was little difference in the oxidation rate in H2O for either amorphous or crystalline surfaces. During O2 oxidation, the crystalline surface preferentially forms GeO and the amorphous surface preferentially forms GeO2. We have also observed preferential oxidation of Ge in the CoGe thin films. During temperature programmed desorption studies, we found that GeO desorption begins near 350 °C and that GeO2 decomposes to GeO and desorbs near 700 °C. More studies of CoGe catalysts are warranted, however GeO desorption may be a concern under reaction conditions when the film is subjected to an oxidizing environment.
关键词： Oxidation,Cobalt germanium,Temperature programmed desorption,Atomic force microscopy,X-ray photoelectron spectroscopy,X-ray diffraction
更新于2025-09-23 15:21:21
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X-ray Photoelectron Spectroscopy Analysis of the Effect of Photoresist Passivation on InGaZnO Thin-film Transistors
摘要： Bottom-gate InGaZnO (IGZO) thin-film transistors (TFTs) with EOC photoresist (PR) passivation were fabricated. Compared to the unpassivated IGZO TFT with a mobility of 6.71 cm2V-1s-1, a hysteresis of 2.42 V and a poor bias stress stability, the PR-passivated IGZO TFT showed good electrical characteristics with a higher mobility of 8.85 cm2V-1s-1, a lower hysteresis of 0.06 V and a more reliable stability (△Vth = 0.36 V) under positive gate bias stress (PBS). The effect of PR passivation on the performance of IGZO-TFT was investigated by x-ray photoelectron spectroscopy (XPS), systemically. The result of XPS spectra of the O 1s core levels indicate that PR passivation effectively suppressed the adsorption/desorption effect on IGZO surface, resulting in fewer unstable states and higher electrical stability. Furthermore, XPS depth profile experiments show that the proportion of elements on the film surface changed and the IGZO surface was In-rich after PR passivation, enhancing the mobility. The PR passivation with low temperature (100 oC) process exhibited good dielectric quality and excellent barrier ability against water and oxygen molecules. Therefore, it may be a good candidate for high-mobility and high-stability flexible TFTs in future.
关键词： XPS,InGaZnO,Photoresist,Thin film transistors,Adsorption/desorption
更新于2025-09-23 15:21:21
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Effects of Anisotropy Field and Easy Axis Dispersions on Squareness Ratio for HDDR-Processed Nd-Fe-B Powders
摘要： Nd-Fe-B magnetic powders produced by the hydrogenation-decomposition-desorption-recombination process have a lower squareness ratio than sintered magnets. In this paper, the anisotropy ?eld (Hk) distribution was assumed to be a horizontally ?ipped lognormal distribution and the effect of the Hk dispersion on the squareness ratio was investigated by using a micromagnetic simulator. As a result, the squareness ratio was very similar to the experimental demagnetization loop, when (cid:2)Hk(cid:3) was 5500 kA/m and σ Hk/(cid:2)Hk(cid:3) was 30%. Moreover, we investigated the easy axis dispersion of grains on squareness ratio in consideration of soft magnetic or nonmagnetic grain boundaries. As a result, the squareness ratio for the nonmagnetic grain boundary was closer to the experimental value; however, it is dif?cult to describe the experimental demagnetization loop by only considering the easy axis dispersion.
关键词： hydrogenation-decomposition-desorption-recombination (HDDR)-processed Nd-Fe-B,horizontally ?ipped lognormal distribution,Anisotropy ?eld and easy axis dispersions,squareness ratio
更新于2025-09-23 15:21:21
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Determination of citalopram in fish brain tissue: benefits of coupling laser diode thermal desorption with low- and high-resolution mass spectrometry
摘要： Recent state-of-the-art methods developed for the analysis of polar xenobiotics from different types of biological matrices usually employ liquid chromatography with mass spectrometry. However, there are limitations when a small amount of sample mass is available. For example, individual benthic invertebrates or fish tissue samples often weigh less than 100 mg (e.g., brain, liver) but are necessary to understand environmental fate and bioaccumulation dynamics. We developed ultra-fast methods based on a direct sample introduction technique. This included coupling laser diode thermal desorption with atmospheric pressure chemical ionization mass spectrometry (LDTD-APCI-MS). We then quantitated a common selective serotonin reuptake inhibitor (citalopram) in brain tissues of individual juvenile fish after in vivo exposure to environmentally relevant concentration. Two mass spectrometric methods based on low (LDTD-APCI-triple quadrupole (QqQ)-MS/MS) and high (LDTD-APCI-high-resolution product scan (HRPS)) resolutions were developed and evaluated. Individual instrument conditions were optimized to achieve an accurate and robust analytical method with minimum sample preparation requirements. We achieved very good recovery (97–108%) across the range of 1–100 ng g?1 for LDTD-APCI-HRPS. LDTD-APCI-QqQ-MS/MS showed poorer performance due to interferences from the matrix at the lowest concentration level. LDTD-APCI ionization was successfully validated for analysis of non-filtered sample extracts. Evaluation of final methods was performed for a set of real fish brain samples, including comparison of LDTD-APCI-HRPS with a previously validated LC-heated electrospray ionization-HRPS method. This new LDTD-APCI-HRPS method avoids the chromatographic step and provides important benefits such as analysis of limited sample masses, lower total sample volume (typically μL), and reduction in analysis time per sample run to a few seconds.
关键词： Ambient ionization,Green chemistry,Laser diode thermal desorption,Psychoactive pharmaceutical,Juvenile fish
更新于2025-09-23 15:21:01
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A Wearable UV Sensor Based on Carbon Nanotube Coated Cotton Thread
摘要： A fabric-compatible UV sensor is presented using a cellulose-based thread coated with single wall carbon nanotube ink. Two-terminal resistive responses of the thread were measured upon exposure to UV, and the effects of intensity, wavelength and on/off cycling were studied. The sensor was tested in the field under direct sunlight, demonstrating practical usability for a wearable/flexible UV sensor system. The results here confirm the potential for an inexpensive wearable sensor in contrast to the conventional rigid and bulky solid state detectors.
关键词： cellulose thread,wearable ultraviolet sensor,ultraviolet radiation,oxygen desorption-adsorption,single wall carbon nanotube
更新于2025-09-23 15:21:01