The Mechanical Properties and Fracture Characteristics of Shale Layered Samples from the Lucaogou Formation Considering Natural Crack and Mineral Distribution.

Shale oil is one of the most promising alternative unconventional energies in the world, and recently the Lucaogou Formation showed significant exploration potential, becoming the primary target in northwestern China. This paper focuses on the mechanical properties and fracture characteristics of shale layered samples from the Lucaogou Formation, conducting uniaxial compressive tests with real-time micro-CT scanning, as well as mineral analysis after failure. It has been found that the mechanical and fracture features are both related to the composition, distribution, content and particle size of minerals, as well as natural fractures. The main crack tends to form in the weak mineral band, for example, calcite or clay band. Since the discontinuous stress usually forms at the interfaces of different minerals, the sample with several major minerals of close content is easier to break into a fractured zone, causing lower uniaxial compressive strength and elastic modulus, compared with the composition of only one dominant mineral. Also, the region will be more fractured after failure if the mineral particles there become smaller. Additionally, although natural cracks have a certain influence on the development of new fractures, not all of the natural ones will propagate into the final fracture network, some of them are just compacted and closed.

Performance Evaluation and Oil Displacement Effect of Amphiphilic Polymer Heavy Oil Activator.

A heavy oil activator is an amphiphilic polymer solution that contains hydrophilic and oleophobic groups. It can enhance heavy oil recovery efficiency. This paper studied the changes in the distribution of the remaining oil after activator flooding and the performance of heavy oil's active agent. Nuclear magnetic resonance spectroscopy, laser confocal microscopy, microscopic visualization, and CT scanning techniques were used to analyze crude oil utilization, and the distribution characteristics of the remaining oil during activator flooding of heavy oil. The results showed that the heavy oil activator solution presented a dense spatial network and good viscosification ability. The activator could reduce the interfacial tension of oil and water, disassemble the heavy components of dispersed heavy oil and reduce the viscosity of heavy oil. The utilization degree of the remaining oil in small and middle pores increased significantly after activator flooding, the remaining oil associated with membranous-like and clusterlike structures was utilized to a high degree, and the decline of light/heavy fraction in heavy oil slowed down. Heavy oil activator improved the swept volume and displacement efficiency of heavy oil, playing a significant role in improving the extent of recovery of heavy oil reservoirs.

Eeffect of ultra-low dose CT scanning on the diagnosis of ankle fracture and the quality of a three-dimensional printing model / 中华放射医学与防护杂志

Objective:To investigate the effect of ultra-low dose (ULD) computed tomography (CT) scanning on the diagnosis of ankle fractures and the quality of a three-dimensional printing (3DP) model.Methods:This study was a prospective study. A total of 61 patients with clinical ankle fractures treated conservatively in Zhuhai Hospital of Guangdong Hospital of Traditional Chinese Medicine from November 2019 to January 2022 were included in this study. Patients underwent standard dose (SD) CT scan and ultra-low dose (ULD) CT scan, respectively. The tube voltage/tube current of SD and ULD were 120 kV/100 mAs and 80 kV/10 mAs, respectively. Two senior radiologists evaluated the presence of ankle fractures. The effective radiation dose ( E), noise, signal-to-noise ratio (SNR), contrast signal-to-noise ratio (CNR), and CT value of bone cortex minus CT value of peripheral fat (CTc) were compared. The radiologists also evaluated the discoverability, diagnosability, and overall image quality of the fracture line according to Likert′s 5-point scoring method. Two senior orthopedists subjectively evaluated the quality of each 3DP model (model clarity and operation guidance). A score ≥ 3 indicated that the quality of the CT diagnostic image and 3DP model were acceptable. Results:The interval between the two CT scans was (9.23 ± 1.92) d. A total of 94 fracture sites were found. There were no missed diagnosis or misdiagnosis based on the SD and ULD scans.Noise, SNR, and CNR were better on the SD CT scanning ( F=5.92, 9.70, 8.32, P=0.00), however, CTc was higher on the ULD scans ( F=27.55, P<0.01). The image scores of the SD and ULD scans were (4.97 ± 0.18) and (4.21 ± 0.71), and the quality scores of the 3DP model (4.99 ± 0.01) and (4.87 ± 0.34), respectively. The SD scans were better than the ULD scans with respect to CT image quality and 3DP model quality ( Z=-6.88, -2.91, P<0.01), but both were considered suitable to meet clinical needs (all ≥ 3 points). The E associated with SD and ULD scannings were (34.68 ± 4.96) μSV and (1.04 ± 0.10) μSV, respectively. The latter was thus significantly better than the former ( F=38.77, P =0.00). Conclusions:The E value of ULD scanning is about 3.00% of SD scanning E, which can meet the needs of clinical diagnosis of ankle fracture and 3DP model printing diagnosis.

Vitamin K for kidney transplant organ recipients: investigating vessel stiffness (ViKTORIES): study rationale and protocol of a randomised controlled trial.

BACKGROUND: Renal transplant recipients (RTRs) exhibit increased vascular stiffness and calcification; these parameters are associated with increased cardiovascular risk. Activity of endogenous calcification inhibitors such as matrix gla protein (MGP) is dependent on vitamin K. RTRs commonly have subclinical vitamin K deficiency. The Vitamin K in kidney Transplant Organ Recipients: Investigating vEssel Stiffness (ViKTORIES) study assesses whether vitamin K supplementation reduces vascular stiffness and calcification in a diverse population of RTR. METHODS AND ANALYSIS: ViKTORIES (ISRCTN22012044) is a single-centre, phase II, parallel-group, randomised, double-blind, placebo-controlled trial of the effect of vitamin K supplementation in 90 prevalent RTR. Participants are eligible if they have a functioning renal transplant for >1 year. Those on warfarin, with atrial fibrillation, estimated glomerular filtration rate <15 mL/min/1.73 m2 or contraindications to MRI are excluded. Treatment is with vitamin K (menadiol diphosphate) 5 mg three times per week for 1 year or matching placebo. All participants have primary and secondary endpoint measures at 0 and 12 months. The primary endpoint is ascending aortic distensibility on cardiac MR imaging. Secondary endpoints include vascular calcification (coronary artery calcium score by CT), cardiac structure and function on MR, carotid-femoral pulse wave velocity, serum uncarboxylated MGP, transplant function, proteinuria and quality of life. The study is powered to detect 1.0×10-3 mm Hg-1 improvement in ascending aortic distensibility in the vitamin K group relative to placebo at 12 months. Analyses will be conducted as between-group differences at 12 months by intention to treat. DISCUSSION: This trial may identify a novel, inexpensive and low-risk treatment to improve surrogate markers of cardiovascular risk in RTR.

Digital dissection of the model organism Xenopus laevis using contrast-enhanced computed tomography.

The African clawed frog, Xenopus laevis, is one of the most widely used model organisms in biological research. However, the most recent anatomical description of X. laevis was produced nearly a century ago. Compared with other anurans, pipid frogs - including X. laevis - exhibit numerous unusual morphological features; thus, anatomical descriptions of more 'typical' frogs do not detail many aspects of X. laevis skeletal and soft-tissue morphology. The relatively new method of using iodine-based agents to stain soft tissues prior to high-resolution X-ray imaging has several advantages over gross dissection, such as enabling dissection of very small and fragile specimens, and preserving the three-dimensional topology of anatomical structures. Here, we use contrast-enhanced computed tomography to produce a high-resolution three-dimensional digital dissection of a post-metamorphic X. laevis to successfully visualize: skeletal and muscular anatomy; the nervous, respiratory, digestive, excretory and reproductive systems; and the major sense organs. Our digital dissection updates and supplements previous anatomical descriptions of this key model organism, and we present the three-dimensional data as interactive portable document format (PDF) files that are easily accessible and freely available for research and educational purposes. The data presented here hold enormous potential for applications beyond descriptive purposes, particularly for biological researchers using this taxon as a model organism, comparative anatomy and biomechanical modelling.