SNIP, a statistics-sensitive background treatment for the quantitative analysis of PIXE spectra in geoscience applications

Ryan, C.G.; Clayton, E.; Griffin, William L.; Sie, S.H.; Cousens, D.R.

doi:10.1016/0168-583x(88)90063-8

Cited by 425 publications

(236 citation statements)

References 4 publications

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“…The Raman spectra of different micelles with and without payloads and the respective polymers were collected using × 100 objective (NA 0.75) as follows: drop of the samples was taken on CaF 2 slides and a region of 10 × 10 μm was scanned with a spectral acquisition time of 10 s. The Raman spectra were pre-processed using GNU R programming platform with in-house-built script (Vienna, Austria). 27 The pre-processing involved spectral background correction 28 and normalization. Each spectrum shown ( Figures 2 and 4) is average of~400 spectra.…”

Section: Fluorescence Spectroscopymentioning

confidence: 99%

Cargo–carrier interactions significantly contribute to micellar conformation and biodistribution

et al. 2017

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Strategies to deliver drugs using nanocarriers, which are passively or actively targeted to their alleged site of action might favorably affect benefit-risk profiles of novel therapeutics. Here we tested the hypothesis whether the physico-chemical properties of the cargo as well as the actual conditions during encapsulation interfere during formulation of nanoparticular cargo-carrier systems. On the basis of previous work, a versatile class of nanocarriers is polyether-based ABC triblock terpolymer micelles with diameters below 50 nm. Their tunable chemistry and size allows to systematically vary important parameters. We demonstrate in vivo differences in pharmacokinetics and biodistribution not only dependent on micellar net charge but also on the properties of encapsulated (model) drugs and their localization within the micelles. On the basis of in vitro and in vivo evidence we propose that depending on drug cargo and encapsulation conditions micelles with homogeneous or heterogeneous corona structure are formed, contributing to an altered pharmacokinetic profile as differences in cargo location occur. Thus, these interactions have to be considered when a carrier system is selected to achieve optimal delivery to a given tissue.

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Section: Fluorescence Spectroscopymentioning

confidence: 99%

Cargo–carrier interactions significantly contribute to micellar conformation and biodistribution

et al. 2017

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“…Spectra were trimmed to 2,000 to 16,000 Da, with intensities transformed using the square root function. Spectra were smoothed with the Savitzky-Golay filter (22), and baseline noise was subtracted using statistics-sensitive nonlinear iterative peak clipping (23). Intensity was calibrated by the total ion current method so that individual spectra could be compared even when the absolute peak heights were dissimilar.…”

Section: Methodsmentioning

confidence: 99%

Rapid Detection of Vancomycin-Intermediate Staphylococcus aureus by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

et al. 2016

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Vancomycin is the standard of care for the treatment of invasive methicillin-resistant Staphylococcus aureus (MRSA) infections. Infections with vancomycin-nonsusceptible MRSA, including vancomycin-intermediate S. aureus (VISA) and heterogeneous VISA (hVISA), are clinically challenging and are associated with poor patient outcomes. The identification of VISA in the clinical laboratory depends on standard susceptibility testing, which takes at least 24 h to complete after isolate subculture, whereas hVISA is not routinely detected in clinical labs. We therefore sought to determine whether VISA and hVISA can be differentiated from vancomycin-susceptible S. aureus (VSSA) using the spectra produced by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Strains of MRSA were characterized for vancomycin susceptibility phenotype by broth microdilution and modified population analysis. We tested 21 VISA, 21 hVISA, and 38 VSSA isolates by MALDI-TOF MS. Susceptibility phenotypes were separated by using a support vector machine (SVM) machine learning algorithm. The resulting model was validated by leave-one-out cross validation. Models were developed and validated by using spectral profiles generated under various subculture conditions, as well as with and without hVISA strains. Using SVM, we correctly identified 100% of the VISA and 97% of the VSSA isolates with an overall classification accuracy of 98%. Addition of hVISA to the model resulted in 76% hVISA identification, 100% VISA identification, and 89% VSSA identification, for an overall classification accuracy of 89%. We conclude that VISA/hVISA and VSSA isolates are separable by MALDI-TOF MS with SVM analysis. Delayed initiation of appropriate antibiotic therapy results in increased mortality rates for patients with sepsis (1-6). Staphylococcus aureus is a pathogen frequently isolated from patients with sepsis, with worse clinical outcomes noted for patients with methicillin-resistant S. aureus (MRSA) (7). Vancomycin remains the standard of care for the treatment of invasive infections with MRSA (8, 9). Infections with vancomycin-nonsusceptible isolates are associated with prolonged bacteremia, longer hospital stays, and greater rates of clinical treatment failure than infections with vancomycin-susceptible S. aureus (VSSA) (10, 11).Vancomycin nonsusceptibility falls into two related phenotypes: vancomycin-intermediate S. aureus (VISA) and heterogeneous VISA (hVISA). The VISA phenotype is reliably detected by broth microdilution, and these strains are characterized by a vancomycin MIC of 4 or 8 g/ml. Reliance on susceptibility testing to identify the VISA phenotype therefore delays the identification of these strains and thus the initiation of appropriate antimicrobial therapy. Because only a subpopulation of cells of hVISA strains (Յ10 Ϫ5 to 10 Ϫ6 ) have vancomycin MICs in the intermediate range, hVISA isolates frequently test susceptible to vancomycin (i.e., MICs of Յ2 g/ml) by broth microdilution methods, which typically tes...

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“…For AIMS, the gamma background -caused by ambient radioactive decay, downscattered gannas, or detector effects -is calculated with the Sensitive Nonlinear Iterative Peak-clipping (SNIP) algorithm, a widely used, statistically robust treatment of background and peak finding in gamma spectra [107,108]. The SNIP algorithm is applied to the gamma spectra in Figure 6-9 with the result plotting in red; The result is a clear delineation between the background and the 0.953 MeV photopeak from the ' 1 B(d, py)12B reaction, which can be integrated to provide quantification of the boron on the PFC surface.…”

Section: Gamma Spectrum Analysismentioning

confidence: 99%

An in situ accelerator-based diagnostic for plasma-material interactions science on magnetic fusion devices

Hartwig

Barnard

Lanza

et al. 2013

Review of Scientific Instruments

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Plasma-material interactions (PMI) in magnetic fusion devices such as fuel retention, material erosion and redeposition, and material mixing present significant scientific and engineering challenges, particularly for the next generation of devices that will move towards reactor-relevant conditions. Achieving an integrated understanding of PMI, however, is severely hindered by a dearth of in-situ diagnosis of the plasma-facing component (PFC) surfaces. To address this critical need, this thesis presents an accelerator-based diagnostic that nondestructively measures the evolution of PFC surfaces in-situ. The diagnostic aims to remotely generate isotopic concentration maps that cover a large fraction of the PFC surfaces on a plasma shot-to-shot timescale.The diagnostic uses a compact, high-current radio-frequency quadrupole accelerator to inject 0.9 MeV deuterons into the Alcator C-Mod tokamak. The tokamak magnetic fields in between plasma shots are used to steer the deuterons to PFCs where the deuterons cause high-Q nuclear reactions with low-Z isotopes ~5 pim into the material. Scintillation detectors measure the induced neutrons and gammas; energy spectra analysis provides quantitative reconstruction of surface concentrations. An overview of the diagnostic technique, known as accelerator-based in-situ materials surveillance (AIMS), and the first AIMS diagnostic on the Alcator C-Mod is given; a description of the complementary simulation tools is also provided. Experimental validation is shown to demonstrate the optimized beam injection into the tokamak, the quantification of PFC surfaces isotopes, and the measurement localization provided by magnetic beam steering. Finally, the first AIMS measurements of fusion fuel retention are presented, demonstrating the local erosion and codeposition of deuterium-saturated boron surface filns. The finding confirms that deuterium codeposition with boron is insufficient to account for the net fuel retention in Alcator C-Mod.

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SNIP, a statistics-sensitive background treatment for the quantitative analysis of PIXE spectra in geoscience applications

Cited by 425 publications

References 4 publications

Cargo–carrier interactions significantly contribute to micellar conformation and biodistribution

Cargo–carrier interactions significantly contribute to micellar conformation and biodistribution

Rapid Detection of Vancomycin-Intermediate Staphylococcus aureus by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

An in situ accelerator-based diagnostic for plasma-material interactions science on magnetic fusion devices

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