Surface-enhanced Raman scattering (SERS) is highly sensitive and label-free analytical technique based on Raman spectroscopy aided by field-multiplying plasmonic nanostructures. We report the use of SERS measurements of patient urine in conjunction with biostatistical algorithms to assess the treatment response of prostate cancer (PCa) in 12 recurrent (Re) and 63 nonrecurrent (NRe) patient cohorts. Multiple Raman spectra are collected from each urine sample using monodisperse silver nanoparticles (AgNPs) for Raman signal enhancement. Genetic algorithmspartial least squares-linear discriminant analysis (GA-PLS-LDA) was employed to analyze the Raman spectra. Comprehensive GA-PLS-LDA analyses of these Raman spectral features (p = 3.50 × 10 −16) yield an accuracy of 86.6%, sensitivity of 86.0%, and specificity 87.1% in differentiating the Re and NRe cohorts. Our study suggests that SERS combined with multivariate GA-PLS-LDA algorithm can potentially be used to detect and monitor the risk of PCa relapse and to aid with decision-making for optimal intermediate secondary therapy to recurred patients.
We report the utility of surface-enhanced Raman scattering (SERS) analysis of urine from deceased donors for prognosis of kidney transplant outcomes. Iodide-modified silver nanoparticles were used as the enabler for sensitive measurements of urine proteins. Principal component analysis (PCA) and linear discriminant analysis (LDA) were employed for the statistical analysis of the SERS data. Thirty urine samples in three classes were analysed. The ATN class consists of donors whose kidneys had acute tubular necrosis (ATN), the most common type of acute kidney injury (AKI) with high risk of poor graft performance in recipients, yet yielded acceptable transplant outcome. The DGF class is comprised of donors whose kidney had delayed graft function (DGF) in recipients. The control class includes donors whose kidneys did not have donor ATN or recipient DGF. We show a sensitivity of more than 90% in differentiating the ATN class from the DGF and control classes. Our methodology can thus help clinicians choose kidneys in the high-risk ATN category for transplant which would otherwise be discarded. Our research is impactful in that it could serve as a valuable guidance to expand the deceased donor pool to include those perceived as high-risk AKI type based on common urinary biomarkers.
Summary Polymer transport and fluid rheology were implemented in a fully implicit hydraulic-fracturing and reservoir simulator. For flow in the matrix, a fluid-rheology function was used with shear thickening at high shear rates and shear thinning at medium and low shear rates. For flow in fractures, a shear-thinning constitutive law with a zero shear-rate plateau was used. The average viscosity in each fracture element was calculated by assuming smooth and parallel fracture walls and numerically solving for the velocity, shear rate, and viscosity distribution across the aperture. The simulator was used to investigate the effect on injectivity of shear thickening at high shear rates near the wellbore. For comparison, simulations were performed by use of the full shear-thickening and shear-thinning rheology function and by use of a shear-thinning-only rheology function. In the former case, the shear thickening caused rapid buildup of fluid pressure and the creation of a hydraulic fracture at the wellbore. Once the fracture formed, shear thickening no longer occurred because there was lower Darcy velocity in the matrix caused by lower concentration of flow at the wellbore. As a result, after the formation of the hydraulic fracture, injectivity in the simulation with shear thickening and thinning was nearly identical to that in the simulation with only shear thinning. The simulations were repeated with the constraint that a hydraulic fracture was not permitted to form. In this case, the simulation with shear thickening had a significantly lower injectivity than the simulation with shear thinning only. This result shows that formation of an induced fracture is a plausible explanation for unexpectedly high injectivity during polymer injection because it prevents shear thickening caused by high flow rate because of concentration of flow at the wellbore. Simulations were performed to investigate the effect of polymer rheology on the pressure transients occurring after shut-in of an injection well. Shear thickening affected the shut-in transient only at very-early time. Shear thinning affected the entire duration of the transient, causing an increase in effective fluid viscosity as the Darcy velocity gradually decreased over time. Despite fluid-rheology effects, linear flow was clearly identifiable after shut-in in the simulations with hydraulic fractures. This result shows that hydraulic fractures around polymer-injection wells can be diagnosed in field data from the linear-flow regime in the shut-in transient, regardless of fluid-rheology effects.
Carbon isotope fractionation is a promising method to predict gas-in-place content and evaluate the shale gas production stage. In this study, molecular simulations are conducted to investigate fractionation characteristics of 12CH4 and 13CH4 in high-Kn (Knudsen number) flows (Kn > 0.1) within organic and inorganic pores under shale reservoir conditions (353 K, 5–25 MPa). The results show that isotope fractionation is more obvious (i.e., the difference in transport capacities between 12CH4 and 13CH4 is larger) in organic pores than in inorganic pores. Methane adsorption capacity and surface roughness of pore walls are two major reasons. High-coverage adsorption in organic pores reduces the effective pore size, and the Knudsen diffusion becomes significant. Moreover, the specular reflection of molecules occurs frequently on the smooth surfaces of organic pores, which enlarges the difference in isotope diffusion capacity. Indeed, the difference in energy (specific enthalpy) transport of methane isotopes in organic and inorganic pores is the intrinsic reason for fractionation. Furthermore, the fractionation level is positively correlated with Kn due to the enhanced contribution of Knudsen diffusion and surface diffusion in high-Kn flows. In addition, the isotope fractionation level decreases as pore size increases because Kn and the contribution of the adsorbed phase to the total molar flux reduce in a large pore. Our findings and related analyses may help us to understand isotope fractionation in different pore types and sizes from the atomic level and assist future applications in engineering.
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