- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Combination of OPSY and PhD-PHIP results in enhanced sensitivity in PHIP
摘要： Despite the large degree of polarization in PHIP experiments compared to the Boltzmann factor, the presence of a large amount of non-reacted molecules with thermal polarization is an important obstacle when dealing with very diluted samples. The feasibility of enhancing both sensitivity and resolution in a single experiment by combining two well established pulse sequences, OPSY and PHD-PHIP is presented. OPSY is used as a block for filtering the signals originated from thermally polarized protons. PhD-PHIP, on the other hand, is used as an acquisition block, increasing the resolution and further improving the sensitivity by preventing signal canceling in the presence of magnetic field inhomogeneities. Experiments in a complex sample with very low hyperpolarization levels are presented showing the excellent performance of the method.
关键词： Echo trains,PhD-PHIP,Spin dynamics,CPMG,J-spectroscopy,Hyperpolarization,Pulse sequences,Parahydrogen,SABRE,J-coupling,NMR,OPSY,PHIP
更新于2025-09-23 15:23:52
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Investigation of Keratinizing Squamous Cell Carcinoma of the Tongue Using Terahertz Reflection Imaging
摘要： We investigated the feasibility of using terahertz (THz) reflection imaging to detect keratinizing squamous cell carcinoma (SCC) of the tongue. Four fresh keratinizing SCC tissues were studied, which had been surgically resected. All of the keratinizing SCCs were well distinguished from normal healthy tissues. We showed that the tumor regions exhibited low THz reflection despite having higher water content than normal regions. The refractive indices and absorption coefficients were low in the tumor tissues despite the relatively high water content. Our results showed that there were dominant factors such as keratin pearls, other than the water content affecting the THz reflection signal.
关键词： Optical diagnostics for medicine,Tissue diagnostics,Terahertz imaging,Medical and biological imaging,Terahertz spectroscopy
更新于2025-09-23 15:23:52
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Synthesis of water-soluble conjugated polymer, poly(N-3-sulfopropylaniline) and the study of its glucose sensing property
摘要： A water-soluble conjugated polymer, poly(N-3-sulfopropylaniline) (PSPA) with 7–10 controlled repeating units has been synthesized through oxidative polymerization of sulfopropylaniline (SPA) monomer, which is prepared by N-alkylation of aniline using 3-propane sultone. The glass transition temperature (Tg), thermal stability, molecular weight and size distribution of the synthesized polymer were investigated by DSC, TGA and MALDI TOFF respectively. The spectral (UV-Vis, PL, NMR, FTIR) analysis has been done to develop a facile colorimetric method to sense glucose (a biomarker of diabetes). The synthesized polymers could detect glucose up to nanomolar (10?9 M), which are 106 fold less than the level of a diabetic patient (4 × 10?3-9 × 10?3 M). It is also observed that the naked eye can sense up to decimolar (10?1 M) level. The polymerization process and the chemistry of colorimetric sensing are explained through spectral and cyclic voltammetry analysis. The polymerization and the sensing of glucose occurred through the electron transfer dependent color change processes.
关键词： Polymerization,Glucose sensing,Spectroscopy,Thermal analysis
更新于2025-09-23 15:23:52
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Fraction of Rare-Earth (Sm/Nd)-Lanthanum Ferrite-Based Perovskite Ferroelectric and Magnetic Nanopowders
摘要： Multiferroic compound, especially LaFeO3-based perovskite nanopowders that exhibit robust simultaneous ferromagnetism and ferroelectricity, are widely investigated and applied in different applications. In this work, we report the synthesis and characterization pertaining to fraction of rare-earth (Sm/Nd)-substituted lanthanum ferrite based perovskite nanopowders via solid-state technique. The multiferroic phenomenon is the fundamental approach to combine both the ferromagnetic and ferroelectric properties in a single system. Reduction in crystallite size, as well as some lattice distortion effects, are included to show the possibilities of tuning the lattice structure, electrical, optical as well as the magnetic properties which are closely connected to the ferroelectric behavior and magnetism. At room temperature, the ferroelectric behavior of La0.9(Sm/Nd)0.1FeO3 exhibiting a P-E hysteresis loop became more and more pronounced, indicating the electrical leakage is greatly reduced. The canted antiferromagnetic hysteresis loop shows that the rare-earth (Sm/Nd) ion can significantly affect the magnetic parameters of the materials.
关键词： Lanthanum ferrite,x-ray diffraction,optical and magnetic properties,solid-state reaction,ferroelectric,UV–Vis spectroscopy
更新于2025-09-23 15:23:52
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A flat-field soft X-ray spectrometer for X-ray absorption spectroscopy measurement of warm dense matter
摘要： A flat-field soft X-ray spectrograph operating in the spectral range of 250–1240 eV was designed and built for warm dense matter and high-energy density plasma physics. It employs a grazing incidence toroidal mirror as a focusing optic, an aberration-corrected variable line spacing concave grating with 2400 lines/mm as a dispersive element, and a charge coupled device as an X-ray detector. The dispersion and energy resolution are calibrated with a high-power laser-produced plasma and X-ray free electron laser sources. A resolving power over 370 was achieved over the entire spectral range. A super broadband spectrum in the range of 250–1000 eV was measured from the laser-produced bismuth plasma. The signal-to-noise of 130 was obtained with an average of 10 pulses. These results demonstrate the capability of the spectrograph for single laser shot based experiments for warm dense matter and high energy density plasma research.
关键词： soft x-ray spectrometer,laser plasma,warm dense matter,x-ray spectroscopy,high power laser
更新于2025-09-23 15:23:52
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The sputtering yield of crystalline Si(1?0?0) surface by monoatomic and diatomic nitrogen ions impact
摘要： We have investigated the sputtering rate of thin crystalline silicon film forming silicon-on-insulator structure impinged by atomic and molecular nitrogen ions with medium energies of 25, 50, and 100 keV/(N atom) at several incident angles of 0, 30, 45, and 60°. The thickness of the surface silicon layer after ion irradiation was quantitatively estimated by Rutherford backscattering spectroscopy using 2.56-MeV 10B2+ ions with a grazing angle geometry to accurately analyze the thickness decrement in several nanometers for ultrathin Si layers. The sputtering rates were compared with a full-cascade TRIM simulation based on a binary collision approximation. We found that the sputtering yields of monoatomic N ion with higher energies (> 50 keV/N) took significantly higher than that of diatomic N2 ion, probably suggesting that a wake-like effect of relatively fast N^N molecular ions surviving for a long period due to a considerably strong triple bond. In addition, the observed sputtering yields for all present conditions were a few times smaller than that estimated by the full-cascade TRIM calculation using typical lattice parameters. We quantitatively discuss the details of sputtering phenomenon of crystalline silicon by nitrogen ions at medium energy region.
关键词： Medium energy,Molecular ion,Sputtering,Rutherford backscattering spectroscopy,Silicon
更新于2025-09-23 15:23:52
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Observation of Site-Resolved Vibrational Energy Transfer Using a Genetically Encoded Ultrafast Heater
摘要： Allosteric information transfer in proteins has been linked to distinct vibrational energy transfer (VET) pathways in a number of theoretical studies. Experimental evidence for such pathways, however, is sparse because site-selective injection of vibrational energy into a protein, i.e. localized heating, is required for their investigation. Here, we solve this problem by the site-specific incorporation of the non-canonical amino acid β-(1-azulenyl)-L-alanine (AzAla) via genetic code expansion. Being an exception to Kasha′s rule, AzAla undergoes ultrafast internal conversion and heating after S1 excitation while upon S2 excitation it serves as a fluorescent label. We endowed PDZ3, a protein interaction domain of postsynaptic density protein 95, with this ultrafast heater at two distinct positions. Using ultrafast IR spectroscopy, we could indeed observe VET from the incorporation sites in the protein to a bound peptide ligand on a picosecond timescale. This approach based on genetically encoded AzAla paves the way for detailed studies of VET and its role for function in a wide range of proteins.
关键词： protein modification,energy transfer,non-canonical amino acid,time-resolved spectroscopy,mutagenesis
更新于2025-09-23 15:23:52
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Progress in development of a new luminescence setup at the FinEstBeAMS beamline of the MAX IV laboratory
摘要： FinEstBeAMS is a new materials science beamline at the 1.5 GeV storage ring of the MAX IV Laboratory in Lund, Sweden. It has been built based on grazing incidence monochromatization of synchrotron light, which allows to cover a remarkably wide excitation energy range from ultraviolet to soft x-rays (4.5-1450 eV). A new mobile luminescence spectroscopy end station has been commissioned with design benefitting from the advantages of a high flux elliptically polarizing undulator light source. We report on the design of the luminescence end station, its technical realization and performance achieved so far. Special attention is paid to the experimental challenges for luminescence spectroscopy under grazing incidence excitation conditions. The first luminescence results obtained demonstrate a reliable performance of the advanced setup at FinEstBeAMS.
关键词： Luminescence spectroscopy,synchrotron radiation,wide gap compounds,VUV – XUV photoexcitation
更新于2025-09-23 15:23:52
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Treatment of disorder effects in X-ray absorption spectra beyond the conventional approach
摘要： The contribution of static and thermal disorder is one of the largest challenges for the accurate determination of the atomic structure from the extended X-ray absorption fine structure (EXAFS). Although there are a number of generally accepted approaches to solve this problem, which are widely used in the EXAFS data analysis, they often provide less accurate results when applied to outer coordination shells around the absorbing atom. In this case, the advanced techniques based on the molecular dynamics and reverse Monte Carlo simulations are known to be more appropriate: their strengths and weaknesses are reviewed here.
关键词： Reverse Monte Carlo,Extended X-ray absorption fine structure (EXAFS),Molecular dynamics,Static and thermal disorder,X-ray absorption spectroscopy
更新于2025-09-23 15:23:52
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Development and first in-human use of a Raman spectroscopy guidance system integrated with a brain biopsy needle
摘要： Navigation-guided brain biopsies are the standard of care for diagnosis of several brain pathologies. However, imprecise targeting and tissue heterogeneity often hinder obtaining high-quality tissue samples, resulting in poor diagnostic yield. We report the development and first clinical testing of a navigation-guided fiberoptic Raman probe that allows surgeons to interrogate brain tissue in situ at the tip of the biopsy needle, prior to tissue removal. The 900μm diameter probe can detect high spectral quality Raman signals in both the fingerprint and high wavenumber spectral regions with minimal disruption to the neurosurgical workflow. The probe was tested in 3 brain tumor patients, and the acquired spectra in both normal brain and tumor tissue demonstrated the expected spectral features, indicating the quality of the data. As a proof-of-concept, we also demonstrate the consistency of the acquired Raman signal with different systems and experimental settings. Additional clinical development is planned to further evaluate the performance of the system and develop a statistical model for real-time tissue classification during the biopsy procedure.
关键词： biopsy,cancer,neurosurgery,optical systems,Raman spectroscopy,medical imaging
更新于2025-09-23 15:23:52