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The influence on sample preparation on spectral induced polarization of unconsolidated sediments
摘要： Spectral induced polarization (SIP) measurements in the laboratory are in many cases intended to provide representative and comparable results of complex electrical conductivity. This is not invariably the case when using unconsolidated sediments, as the sample preparation influences several SIP-relevant properties of the samples, including the pore geometry. The pore space is supposed to control the polarization effect and therefore a change in the pore space will change the measured parameters. We analysed the influence of the sample preparation on SIP measurements by testing various filling methods, each defined by a sequence of particular steps, with regard to the reproducibility of the spectra. The measurements were performed on three different sample materials. Variations of the spectra due to different filling methods were obtained, indicating the importance of considering the sample preparation. Methods that improved the reproducibility compared to loose packing of the samples were found, but the most suitable packing procedure depended on the material properties. The mean relaxation times and normalized chargeabilities were obtained from a Debye decomposition. Although unidentified processes caused scattering of the measured parameters, a relation of the IP-parameters to the porosities was present. A decrease of the porosity reduced both the relaxation times and the normalized chargeabilities.
关键词： Debye decomposition,sample preparation,unconsolidated sediments,reproducibility,spectral induced polarization,porosity
更新于2025-09-23 15:22:29
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Reproducibility of Disc and Macula Optical Coherence Tomography using the Canon OCT-HS100 as Compared with the Zeiss Cirrus HD-OCT
摘要： Purpose: In a clinical setting, the usefulness of optical coherence tomography (OCT) is strongly dependent on reproducibility of the measurement. The aim of the present study was to evaluate macula and optic disc measurement reproducibility with the new spectral-domain OCT (SD-OCT) from Canon (Canon OCT-HS100) and to compare reproducibility and obtained measurements with the Zeiss Cirrus HD-OCT. Methods: Macula and optic disc parameters from the right eyes of 31 subjects were obtained twice with both instruments. Interoperator reproducibility was evaluated by use of the coefficient of repeatability (CR), and the obtained measurements were compared between the instruments. Results: No difference in interoperator reproducibility could be found when comparing the 2 instruments and reproducibility ranged from 3.94% to 12.77% for optic disc parameters and from 1.19% to 3.54% for macula parameters. The lowest reproducibility was found for cup volume and vertical cup/disc ratio with both instruments. For all macula and retinal nerve fiber layer (RNFL) thickness measurements, there was a statistical difference when comparing the 2 instruments, except for RFNL measurements of the superior quadrant, with the Canon OCT-HS100 always evaluating the thickness to be thicker; however, the 2 instruments correlated well. Conclusions: The Canon OCT-HS100 is a reproducible instrument that matches the Zeiss Cirrus HD-OCT well. It remains to be evaluated how sensitive the Canon OCT-HS100 is to detect small subtle changes in optic disc parameters and macular nerve fiber layer thickness. Furthermore, due to the differences in thickness estimation, it is important to emphasize that SD-OCTs are not interchangeable.
关键词： Canon OCT-HS100,Reproducibility,Spectral domain,Optical coherence tomography
更新于2025-09-23 15:22:29
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Site-to-Site Reproducibility and Spatial Resolution in MALDI-MSI of Peptides from Formalin-Fixed Paraffin-Embedded Samples
摘要： Purpose To facilitate the transition of MALDI-MS Imaging (MALDI-MSI) from basic science to clinical application, it is necessary to analyze formalin-fixed paraffin-embedded (FFPE) tissues. Our aim was to improve in-situ tryptic digestion for MALDI-MSI of FFPE samples and determine if similar results would be reproducible if obtained from different sites. Experimental Design FFPE tissues (mouse intestine, human ovarian teratoma, tissue microarray of tumor entities sampled from three different sites) were prepared for MALDI-MSI. Samples were coated with trypsin using an automated sprayer then incubated using deliquescence to maintain a stable humid environment. After digestion, samples were sprayed with CHCA using the same spraying device and analyzed with a rapifleX MALDI Tissuetyper at 50μm spatial resolution. Data were analyzed using flexImaging, SCiLS and R. Results Trypsin application and digestion were identified as sources of variation and loss of spatial resolution in the MALDI-MSI of FFPE samples. Using the described workflow, it is possible to discriminate discrete histological features in different tissues and enabled different sites to generate images of similar quality when assessed by spatial segmentation and PCA. Conclusions and Clinical Relevance Spatial resolution and site-to-site reproducibility can be maintained by adhering to a standardized MALDI-MSI workflow.
关键词： Reproducibility,Tissue typing,MALDI,Workflow,Formalin-fixed paraffin embedded tissue
更新于2025-09-23 15:21:21
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Highly ordered Au-decorated Ag nanorod arrays as an ultrasensitive and reusable substrate for surface enhanced Raman scattering
摘要： For surface-enhanced Raman spectroscopy (SERS) substrates, complexity of the fabrication process, sensitivity and stability are factors that need to be considered. We report a simple and novel method for preparing an effective substrate that greatly enhances SERS signals. The SERS substrate is fabricated by selectively electroless deposition of Ag nanoparticles in the highly ordered porous anodized aluminum oxide (AAO) template and then etching it to form Ag nanorod bundles structure, so that the Raman enhancement occurs in the gap between the nanorods and the top of the nanorod bundle, which is verified by finite element analysis. A peculiarity of this method is that this is the first time to synthesize Ag nanorod arrays structure by using it. The results indicated that this prepared substrate has special micro-nano structure and when rhodamine 6 G is selected as the detection reagent, the detection limit is as low as 10?16 M with excellent recyclability. This outstanding array structure has a promising practical application in SERS field.
关键词： Reproducibility,Electroless deposition,Micro-nano structure,SERS,Ag nanorod arrays
更新于2025-09-23 15:21:21
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Graphene/TiO2 nanocomposite electrodes sensitized with tin sulfide quantum dots for energy issues
摘要： In this work, graphene (Gr)/TiO2 nanocomposite electrodes sensitized with tin sulfide quantum dots (SnS QDs) for energy issues have been investigated. Different sizes of SnS QDs as non-toxic and earth-abundant semi-conducting materials are synthesized onto Gr/TiO2 nanocomposite electrodes using successive ionic layer adsorption and reaction (SILAR) technique for “n” cycles (n: 1 to 8). The structural properties of the prepared SnS (n) QDs photoanodes are studied using an X-ray diffractometer. The XRD measurements ensure the formation of the crystalline structure of orthorhombic SnS QDs. The optical properties of the synthesized SnS(n) QDs photoanodes are characterized using a UV–visible spectrophotometer. The estimated direct (indirect) energy band gap (Eg) of the prepared SnS(n) photoanodes is tuned from 2.36 (1.57) eV to 1.76 (1.30) eV by controlling the number of SILAR cycles from 1 to 8. The photovoltaic performance of the assembled SnS(n) quantum dots sensitized solar cells (QDSSCs) has been studied under a solar power illumination of AM1.5 conditions. The optimal photovoltaic performance of the assembled SnS(n) QDSSCs is achieved at 6 SILAR deposition cycles. As compared with previous studies, enhancement of 48% in the energy conversion efficiency η has been achieved due to the active Gr incorporation. SnS(n) QDSSCs shows high reproducibility and sensitivity undercutting ON-OFF the solar illumination. Gr plays the role of kids slide for the photo-generated electrons and facilitates their transportation.
关键词： Graphene/TiO2,Reproducibility of QDSSCs,Recombination suppression,Tuning band gap,SnS solar Cell
更新于2025-09-23 15:19:57
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Surface-plasmon-enhanced optical formaldehyde sensor based on CdSe@ZnS quantum dots
摘要： For the first time, a reproducible surface-plasmon-enhanced optical sensor for the detection of gaseous formaldehyde was proposed by depositing the mixture of CdSe@ZnS quantum dots (QDs), fumed silica (FS) and gold nanoparticles (GNs) on the surface of silica spheres array to meet the urgent requirement of a rapid, sensitive, and highly convenient formaldehyde detection method. Due to the spectra overlap between QDs and GNs, plasmon-enhanced fluorescence was observed in the film of QDs/FS/GNs. When exposing to formaldehyde molecules, the enhanced fluorescence was quenched linearly with the increase of formaldehyde concentration in the range of 0.5-2.0 ppm. The reason is attributed to the nonradiative electron transfer from QDs to the carbonyl of formaldehyde molecules with the assistance of amino groups. Our results demonstrate that the designed sensors are capable of detecting ultralow concentration gaseous formaldehyde at room temperature with a fast response-recovery time, excellent selectivity, stability and reproducibility. This work provides a simple and low-cost approach for optical formaldehyde sensor fabrication and shows promising applications in environmental detection.
关键词： plasmon-enhanced fluorescence,Quantum dots,reproducibility,Optical formaldehyde sensors,fluorescence quenching
更新于2025-09-23 15:19:57
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Transcranial Photobiomodulation (tPBM) With 1,064a??nm Laser to Improve Cerebral Metabolism of the Human Brain In Vivo
摘要： Background and Objectives: In our previous proof‐of‐principle study, transcranial photobiomodulation (tPBM) with 1,064‐nm laser was reported to significantly increase concentration changes of oxygenated hemoglobin (Δ[HbO]) and oxidized‐state cytochrome c oxidase (Δ[oxi‐CCO]) in the human brain. This paper further investigated (i) its validity in two different subsets of young human subjects at two study sites over a period of 3 years and (ii) age‐related effects of tPBM by comparing sham‐controlled increases of Δ[HbO] and Δ[oxi‐CCO] between young and older adults. Study Design/Materials and Methods: We measured sham‐controlled Δ[HbO] and Δ[oxi‐CCO] using broadband near‐infrared spectroscopy (bb‐NIRS) in 15 young (26.7 ± 2.7 years of age) and 5 older (68.2 ± 4.8 years of age) healthy normal subjects before, during, and after right‐forehead tPBM/sham stimulation with 1,064‐nm laser. Student t tests were used to test statistical differences in tPBM‐induced Δ[HbO] and Δ[oxi‐CCO] (i) between the 15 young subjects and those of 11 reported previously and (ii) between the two age groups measured in this study. Results: Statistical analysis showed that no significant difference existed in Δ[HbO] and Δ[oxi‐CCO] during and post tPBM between the two subsets of young subjects at two study sites over a period of 3 years. Furthermore, the two age groups showed statistically identical net increases in sham‐controlled Δ[HbO] and Δ[oxi‐CCO]. Conclusions: This study provided strong evidence to validate/confirm our previous findings that tPBM with 1,064‐nm laser enables to increase cerebral Δ[HbO] and Δ[oxi‐CCO] in the human brain, as measured by bb‐NIRS. Overall, it demonstrated the robust reproducibility of tPBM being able to improve cerebral hemodynamics and metabolism of the human brain in vivo in both young and older adults.
关键词： transcranial photobiomodulation,cytochrome c oxidase,reproducibility,broadband near‐infrared spectroscopy,tPBM
更新于2025-09-23 15:19:57
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Improvements and reproducibility of an optimal grazing-incidence position method to L-shell x-ray fluorescence measurements of lead in bone and soft tissue phantoms
摘要： L-shell x-ray ?uorescence (LXRF) is a non-invasive approach to lead (Pb) concentration measurements in human bone. The method is based on the detection of the characteristic x-ray photons of Pb at 10.5 and 12.6 keV and experimental studies were designed to perform in vivo human bone Pb measurements. In later studies, however, the initial LXRF methodology was shown to have poor accuracy and precision. In a recent publication, we investigated an optimal grazing-incidence position (OGIP) approach using a sub-millimeter x-ray beam from an integrated x-ray tube and polycapillary x-ray lens table-top system. The OGIP method effectively reduced the x-ray scatter and produced a Pb detection limit of ～5 μg/g for a 2 mm soft tissue phantom thickness. In this study, the OGIP methodology was improved by using 10 s x-ray spectra acquisitions at sequential positions 0.5 mm apart. The measured Sr Kα peak height versus position data was used to spectroscopically identify the bone phantom and the OGIP. The data was ?tted with the analytical convolution between a Gaussian and an exponential decay. The position corresponding to the maximum of the ?tted convolution function was then selected as the OGIP. Four phantom sets were used. A cylindrical plaster-of-Paris bone phantom doped with Pb in a concentration of 74 μg/g was used as a bare bone phantom or with one of the three overlying polyoxymethylene cylindrical shell soft tissue phantoms of 1, 2, and 3 mm thickness. The reproducibility of the OGIP method was assessed in ?ve independent trials using each of the four phantom sets. The coef?cient of variation (COV) percentage values of the Sr Kα peak height measurements were below 5%. The new procedure decreased by more than threefold the duration and radiation dose of the earlier approach.
关键词： bone lead,reproducibility,LXRF
更新于2025-09-19 17:15:36
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Stability Improvement and Performance Reproducibility Enhancement of Perovskite Solar Cells Following (FA/MA/Cs) PbI3-xBrx/(CH3)3SPbI3 Dimensionality Engineering
摘要： Mixed halide hybrid perovskites are strong candidates for fabrication of efficient, stable and reproducible perovskite solar cells (PSCs). To restrain intrinsic volatility and ionic migration effects, we report for the first time a dimensionality engineering approach consisting of a (FA/MA/Cs) PbI3-xBrx/(CH3)3SPbI3 (3D/1D) perovskite bilayer architecture, fabricated exclusively with solution processes. XRPD analysis showed no degradation of the 3D/1D composite structure after more than one month of exposure in ambient conditions, in contrast to the reference 3D samples (sole (FA/MA/Cs) PbI3-xBrx) which gradually decomposed to PbI2. The 3D/1D bilayer structure further optimizes the corresponding absorber/hole transporting layer (HTL) interface of the PSCs, since the (FA/MA/Cs) PbI3-xBrx perovskite layer acts as the primary absorber and the (CH3)3SPbI3 top layer plays the role of a barrier against ionic migration/charge carrier recombination. The latter leads to significant stability improvement for non-sealed devices both under ambient conditions and after light stress, underscoring the potential of interface engineering for developing highly efficient and stable PSCs based on functional 3D/1D perovskite bilayers.
关键词： mesoporous architecture,dimensionality engineering,perovskite solar cells,stability and reproducibility,3D/1D absorber
更新于2025-09-19 17:13:59
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In vivo diffusiona??weighted MRS using semia??LASER in the human brain at 3??T: Methodological aspects and clinical feasibility
摘要： Diffusion‐weighted (DW‐) MRS investigates non‐invasively microstructural properties of tissue by probing metabolite diffusion in vivo. Despite the growing interest in DW‐MRS for clinical applications, little has been published on the reproducibility of this technique. In this study, we explored the optimization of a single‐voxel DW‐semi‐LASER sequence for clinical applications at 3 T, and evaluated the reproducibility of the method under different experimental conditions. DW‐MRS measurements were carried out in 10 healthy participants and repeated across three sessions. Metabolite apparent diffusion coefficients (ADCs) were calculated from mono‐exponential fits (ADCexp) up to b = 3300 s/mm2, and from the diffusional kurtosis approach (ADCK) up to b = 7300 s/mm2. The inter‐subject variabilities of ADCs of N‐acetylaspartate + N‐acetylaspartylglutamate (tNAA), creatine + phosphocreatine, choline containing compounds, and myo‐inositol were calculated in the posterior cingulate cortex (PCC) and in the corona radiata (CR). We explored the effect of physiological motion on the DW‐MRS signal and the importance of cardiac gating and peak thresholding to account for signal amplitude fluctuations. Additionally, we investigated the dependence of the intra‐subject variability on the acquisition scheme using a bootstrapping resampling method. Coefficients of variation were lower in PCC than CR, likely due to the different sensitivities to motion artifacts of the two regions. Finally, we computed coefficients of repeatability for ADCexp and performed power calculations needed for designing clinical studies. The power calculation for ADCexp of tNAA showed that in the PCC seven subjects per group are sufficient to detect a difference of 5% between two groups with an acquisition time of 4 min, suggesting that ADCexp of tNAA is a suitable marker for disease‐related intracellular alteration even in small case–control studies. In the CR, further work is needed to evaluate the voxel size and location that minimize the motion artifacts and variability of the ADC measurements.
关键词： optimization,power calculation,repeatability,diffusion,reproducibility,metabolites
更新于2025-09-19 17:13:59