Study on the Wettability Alteration of Tight Sandstone by Low-Frequency Vibration and Nanofluid.

The efficiency of reservoir imbibition in continental tight sandstone reservoirs is severely hindered due to their intricate wettability characteristics. To address this challenge, we propose a novel synergistic approach that combines low-frequency vibration and nanofluid treatment. This method integrates physical shear and chemical wettability alteration to effectively modify the wettability of neutral oil-wet tight sandstone, thereby enhancing the imbibition process. In this study, we formulated a TX-100 nanofluid system through physical modification. By utilizing the contact angle as a benchmark for evaluation, we investigated the impact of low-frequency fluctuations on the wettability of oil-wet sandstone. Subsequently, we identified the optimal combination of wave parameters. Through isothermal adsorption experiments and mechanical analyses of oil droplets subjected to fluctuations, we systematically elucidated the mechanism by which fluctuations collaborate with nanofluids to alter the wettability of oil-wet sandstone. Furthermore, we evaluated the oil displacement efficiency of cores subjected to the combined action of low-frequency fluctuations and nanofluid treatment. Our findings revealed that the TX-100 nanofluid reduced the static contact angle of oil-wet sandstone by 58%. When assisted by the optimal fluctuation parameters, the nanofluid treatment contributed to a 64% reduction in the contact angle of strongly oil-wet sandstone. This effect further amplified the reversal of wettability in oil-wet sandstone. Through the application of various wave-assisted treatment agents, the efficiency of oil removal was increased by a minimum of 16%. Moreover, the recovery degree of wave-assisted nanofluid imbibition experienced a remarkable enhancement of 30.39%. Nuclear magnetic resonance analysis demonstrated a significant improvement in pore sizes smaller than 1 µm as a result of the composite process.

Increased Dynamic Amplitude of Low Frequency Fluctuation in Primary Insomnia.

The physiological mechanism underlying primary insomnia (PI) is poorly understood. Resting-state functional magnetic resonance imaging (fMRI) has emerged as a powerful tool to explore PI. However, previous studies ignore the dynamics of the brain activity. In the current study, we aimed to explore altered dynamic intrinsic brain activity in PI. Fifty-nine patients with PI and 47 matched healthy controls (HCs) were recruited and underwent resting-state fMRI. The variance of dynamic amplitude of low frequency fluctuation (dALFF) maps across time was calculated to measure the temporal variability of intrinsic brain activity and then compared between patients with PI and HCs. As a result, patients with PI presented increased variance of dALFF in the bilateral hippocampus extending to the parahippocampus, the right putamen and the right anterior insula cortex. In addition, the variance of dALFF in the right putamen was positively correlated with Self-rating Anxiety Scale (SAS) score in PI. Our results revealed increased instability of intrinsic activity in PI.

Diffusion-Weighted MRI for the Initial Viability Evaluation of Parasites in Hepatic Alveolar Echinococcosis: Comparison with Positron Emission Tomography.

Objective: More than 70% of hepatic alveolar echinococcosis (HAE) are inoperable. Thus, long-term, or even life-long, pharmacological treatment with benzimidazoles is necessary. For effective treatment, it is of great importance to employ imaging techniques to detect and monitor the non-resectable parasitic viability. Therefore, this study aimed to evaluate diffusion-weighted imaging (DWI) in assessing the viability of HAE in comparison to 18-fluoro-deoxyglucose (18F-FDG) positron emission tomography, combined with computed tomography (PET/CT). Materials and Methods: Positron emission tomography, computed tomography and DWI (b-values: 0, 800 s/mm2) were retrospectively analysed in eight patients with clinically-verified HAE to, generate the apparent diffusion coefficient (ADC) map. The activity of HAE lesions in both techniques were determined independently by two radiologists according to the following standard: (+), marked focally or perilesionally increased FDG uptake/high signal intensity; (-), a hepatic defect without FDG uptake/no high signal intensity. Every lesion's maximum standardized uptake value (SUVmax) on the PET/CT images and mean ADC values on the parametric ADC maps were measured respectively. Results of PET/CT and DWI were compared on a per-lesion-basis. Pearson's correlation coefficient was assessed for statistical analysis. Results: A total of 14 HAE lesions were detected. Eight lesions (diameter 3-15 cm) showed perilesional hyper-signal intensity on DWI. This was visualised on PET/CT as increased FDG uptake. They mainly existed in the lesion's border with normal liver parenchyma. Five lesions (diameter < 2 cm) were detected as nodular hyperintensity on DWI and a 'hot spot' on PET/CT in the same distribution. One patient, who had received oral drug therapy for three years showed significantly decreased perilesional hyperintensity on the DWI and a hepatic defect without any FDG uptake on PET/CT. Pearson's correlation coefficient indicated a significant inverse correlation of the ADC and the SUVmax (r = -0.67, p < 0.001). Conclusion: Diffusion-weighted imaging is capable of offering information on visually detecting the HAE lesions' viability and may be useful for routine application in the initial diagnosis of HAE.