The effect of nanoparticle shape on the ionic conductivity and thermal properties of solid polymer electrolytes is reported. Poly(ethylene oxide) (PEO) and LiClO 4 electrolytes with an ether oxygen to Li + molar ratio of 10:1 are filled with TiO 2 nanorods and elliptical-shaped fillers in the concentration ranges of 1−2.5 and 1−10 wt %, respectively. The filler concentration that provides the maximum improvement in the ionic conductivity scales inversely with aspect ratio (AR): 10 wt % for spherical nanoparticles (AR = 1), 5 wt % for ellipses (AR ≈ 4.4), and 1−2 wt % for nanorods (AR ≈ 6.6). The same trend is true for Fe 2 O 3 nanofillers, suggesting that the observation is independent of the chemical identity of the metal oxide filler. While the filler concentration required to maximize the conductivity improvement is correlated to the nanofiller shape, the magnitude of the improvement is correlated to the surface-to-volume ratio of the filler. Specifically, the conductivity increases 1 order of magnitude by increasing the surface-to-volume ratio by 5×, illustrating the critical role of the filler surface and suggesting that ion transport is favored at the electrolyte−filler interface over the bulk. Thermal measurements indicate an unexpected relationship between crystallinity and conductivity: the room-temperature conductivity of the electrolyte with 2 wt % TiO 2 nanorods is 1 order of magnitude higher than that with 5 wt % elliptical TiO 2 , even though the nanorod sample is semicrystalline while the elliptical sample is amorphous. The results uncover shape−property relationships that can serve as design rules for solid polymer electrolytes filled with metal oxide nanofillers.
. Significance : Peripheral pitting edema is a clinician-administered measure for grading edema. Peripheral edema is graded 0, , , , or , but subjectivity is a major limitation of this technique. A pilot clinical study for short-wave infrared (SWIR) molecular chemical imaging (MCI) effectiveness as an objective, non-contact quantitative peripheral edema measure is underway. Aim : We explore if SWIR MCI can differentiate populations with and without peripheral edema. Further, we evaluate the technology for correctly stratifying subjects with peripheral edema. Approach : SWIR MCI of shins from healthy subjects and heart failure (HF) patients was performed. Partial least squares discriminant analysis (PLS-DA) was used to discriminate the two populations. PLS regression (PLSR) was applied to assess the ability of MCI to grade edema. Results : Average spectra from edema exhibited higher water absorption than non-edema spectra. SWIR MCI differentiated healthy volunteers from a population representing all pitting edema grades with 97.1% accuracy ( shins). Additionally, SWIR MCI correctly classified shin pitting edema levels in patients with 81.6% accuracy. Conclusions : Our study successfully achieved the two primary endpoints. Application of SWIR MCI to monitor patients while actively receiving HF treatment is necessary to validate SWIR MCI as an HF monitoring technology.
. Significance: Noninvasive diffuse optical spectroscopy (DOS) is a promising adjunct diagnostic imaging technique for distinguishing benign and malignant breast lesions. Most DOS approaches require normalizing lesion biomarkers to healthy tissue since major tissue constituents exhibit large interpatient variations. However, absolute optical biomarkers are desirable as it avoids reference measurements which may be difficult or impractical to acquire. Aim: Our goal is to determine whether absolute measurements of minor absorbers such as collagen and methemoglobin (metHb) can successfully distinguish lesions. We hypothesize that metHb would exhibit less interpatient variability and be more suitable as an absolute metric for malignancy. However, we would expect collagen to exhibit more variability, because unlike metHb, collagen is also present in the healthy tissue. Approach: In this retrospective clinical study, 30 lesions with breast imaging reporting and database system score (12 benign and 18 malignant) measured with broadband quantitative DOS were analyzed for their oxyhemoglobin (HbO), deoxyhemoglobin (HHb), water, lipids, collagen, metHb concentrations, and optical scattering characteristics. Wilcoxon rank sum test was used to compare benign and malignant lesions for all variables in both normalized and absolute forms. Results: Among all absolute DOS parameters considered, only absolute metHb was observed to be significant for lesion discrimination ( for benign versus for malignant, ). Absolute metHb concentration was also determined to be the best predictor of malignancy with an area under the curve of 0.89. Conclusions: Our findings demonstrate that lesion metHb concentration measured by DOS can improve noninvasive optical diagnosis of breast malignancies. Since metHb concentration found in normal breast tissue is extremely low, metHb may be a more direct indicator of malignancy that does not depend on other biomarkers found in healthy tissue with significant variability. Furthermore, absolute parameters require reduced measurement time and can be utilized in cases where healthy reference tissue is not available.
A hybrid reflectance-based diffuse optical imaging (DOI) technique combining discrete wavelength frequency-domain (FD) near-infrared spectroscopy (NIRS) with broadband continuous wave NIRS measurements was developed to quantify the broadband optical properties of deep tumor-like inclusions. This method was developed to more accurately measure the broadband optical properties of human tumors using a compact handheld imaging probe and without requiring a priori spectral constraints. We simulated the reconstruction of absorption and scattering spectra (650–1000 nm) of human breast tumors in a homogeneous background at depths of 0 to 10 mm. The hybrid DOI technique demonstrated enhanced performance in reconstruction of optical absorption with a mean accuracy over all 71 wavelengths of 8.39% versus 32.26% for a 10 mm deep tumor with the topographic DOI method. The new hybrid technique was also tested and validated on two heterogeneous tissue-simulating phantoms with inclusion depths of 2, 7, and 9 mm. The mean optical absorption accuracy over all wavelengths was similarly improved up to 5x for the hybrid DOI method versus topographic DOI for the deepest inclusions.
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