Damage evolution characteristics of siliceous slate with varying initial water content during freeze-thaw cycles.

Comprehensive studies on the freeze-thaw (F-T) damage mechanism in siliceous slates are lacking. In this study, we investigated the evolutionary characteristics of F-T damage in siliceous slates. To this end, scanning electron microscopy, X-ray diffraction, X-ray fluorescence, and uniaxial compression tests were used to analyze the microstructure, phase composition, porosity, and macroscopic mechanical parameters of siliceous slate with varying initial water content during F-T cycles. The results revealed several insights. (1) The microstructure of siliceous slate undergoes significant change with respect to increasing water content and number of F-T cycles. The rock surface changed from smooth to rough, and the arrangement of the mineral particles changed from tight to loose. (2) More than 80 % of the contents of siliceous slate comprise oxygen, aluminum, silicon, potassium, and iron. In particular, siliceous slate comprises muscovite, quartz, clinochlore, and kaolinite. Both the clinochlore and kaolinite are unstable clay minerals. As clay minerals exhibit strong water absorption and expansion characteristics, kaolinite undergoes strong hydration reactions. Compared to rock samples without F-T cycles in the dry state, the clay mineral content of siliceous slate decreased by nearly 50 %, from 28.8 % to 15.5 %, after 30 F-T cycles in the saturated state. (3) The mechanical parameters of siliceous slates with varying water content decreased exponentially with the number of F-T cycles, while their porosity exhibited a positive correlation with the number of F-T cycles. The degree of deterioration in both increased with increasing water content. Both the number of F-T cycles and the initial water content were observed to wield a significant effect on the deterioration of siliceous slates. (4) The evolution curve of F-T load damage in siliceous slate exhibited characteristics of transitioning from gentle to concave and then to a convex stage of growth. Our results are expected to provide theoretical guidance for the evaluation and prevention of F-T disasters in cold regions.

Models of cardiovascular surgery biobanking to facilitate translational research and precision medicine.

Biobanking in health care has evolved over the last few decades from simple biological sample repositories to complex and dynamic units with multi-organizational infrastructure networks and has become an essential tool for modern medical research. Cardiovascular tissue biobanking provides a unique opportunity to utilize cardiac and vascular samples for translational research into heart failure and other related pathologies. Current techniques for diagnosis, classification, and treatment monitoring of cardiac disease relies primarily on interpretation of clinical signs, imaging, and blood biomarkers. Further research at the disease source (i.e. myocardium and blood vessels) has been limited by a relative lack of access to quality human cardiac tissue and the inherent shortcomings of most animal models of heart disease. In this review, we describe a model for cardiovascular tissue biobanking and databasing, and its potential to facilitate basic and translational research. We share techniques to procure endocardial samples from patients with hypertrophic cardiomyopathy, heart failure with reduced ejection fraction, and heart failure with preserved ejection fraction, in addition to aortic disease samples. We discuss some of the issues with respect to data collection, privacy, biobank consent, and the governance of tissue biobanking. The development of tissue biobanks as described here has significant scope to improve and facilitate translational research in multi-omic fields such as genomics, transcriptomics, proteomics, and metabolomics. This research heralds an era of precision medicine, in which patients with cardiovascular pathology can be provided with optimized and personalized medical care for the treatment of their individual phenotype.

Clinical outcome following anterior arthrodesis in patients with presumed sacroiliac joint pain.

BACKGROUND: It has been reported that in 13-32% of patients with chronic low back pain, the pain may originate in the sacroiliac (SI) joints. When treatment of these patients with analgesics and physiotherapy has failed, a surgical solution may be discussed. Results of such surgery are often based on small series, retrospective analyses or studies using a minimal invasive technique, frequently sponsored by manufacturers. PURPOSE: To report the clinical outcome concerning pain, function and quality of life following anterior arthrodesis in patients presumed to have SI joint pain using validated questionnaires pre- and post-operatively. An additional aim was to describe the symptoms of the patients included and the preoperative investigations performed. MATERIAL AND METHODS: Over a 6 year period we treated 55 patients, all women, with a mean age of 45 years (range 28-65) and a mean pelvic pain duration of 9.1 years (range 2-30). The pain started in connection with minor trauma in seven patients, pregnancy in 20 and unspecified in 28. All patients had undergone long periods of treatment including physiotherapy, manipulation, needling, pelvic belt, massage and chiropractic without success, and 15 had been operated for various spinal diagnoses without improvement. The patients underwent thorough neurological investigation, plain X-ray and MRI of the spine and plain X-ray of the pelvis. They were investigated by seven clinical tests aimed at indicating pain from the SI joints. In addition, all patients underwent a percutaneous mechanical provocation test and extra-articular local anaesthetic blocks against the posterior part of the SI joints. Before surgery all patients answered the generic Short-Form-36 (SF-36) questionnaire, the disease specific Balanced Inventory for Spinal Disorders (BIS) questionnaire and rated their level of pelvic and leg pain (VAS, 0-100). At follow-up at a mean of 2 years 49 patients completed the same questionnaires (89%). RESULTS: At follow-up 26 patients reported a lower level of pelvic pain than before surgery, 16 the same level and six a higher level. Applying Svensson's method RPpelvic pain=0.3976, with 95% CI (0.2211, 0.5740) revealed a statistically significant systematic improvement in pelvic pain. At follow-up 28 patients reported a higher quality of life and 26 reported sleeping better than pre-operatively. In most patients the character of the pelvic pain was dull and aching, often accompanied by a stabbing component in connection with sudden movements. Referred pain down the leg/s even to the feet and toes was noted by half of the patients and 29 experienced frequency of micturition. CONCLUSIONS: It is apparent that in some patients the SI joints may cause long-term pain that can be treated by arthrodesis. We speculate that continued pain despite a healed arthrodesis may be due to persistent pain from adjacent ligaments. The next step should be a prospective randomized study comparing posterior fusion and ligament resection with non-surgical treatment. IMPLICATIONS: Anterior arthrodesis can apparently relieve pain in some patients with presumed SI joint pain. The problem is how to identify these patients within the low back pain group.

Nausea, vomiting and return of bowel function after colorectal surgery.

BACKGROUND: Although patterns of return of bowel function (ROBF) following colorectal surgery with enhanced recovery after surgery (ERAS) programmes have been well delineated, regular morphine use is uncommon. This study describes the patterns of post-operative nausea and vomiting (PONV) and ROBF in this context. METHOD: Patients undergoing elective major colorectal surgery on an ERAS programme over 1 year were included. Patient details, intra-operative course, post-operative management, outcomes and complications were collected retrospectively from clinical records. Statistical analysis was performed using Stata version 12. RESULTS: A total of 136/142 (96%) patients received morphine for post-operative analgesia. Most (112/142, 79%) experienced either no vomiting (87/142, 61%) or small amounts (25/142, 18%). On average, patients without an ileostomy passed flatus and opened their bowels after 2.4 and 4.3 days, those with an ileostomy taking 1.5 and 2.1 days. Vomiting was not related to ROBF (P = 0.370) or overall complications; wound complications (odds ratio (OR) = 8.1, 95% confidence interval (CI): 2.0-32.5), electrolyte abnormalities (OR = 2.9, 95% CI: 1.2-7.1) and length of stay (hazard ratio = 1.3, 95% CI: 1.2-1.5) were related. CONCLUSION: Most patients do not experience PONV in this context. ROBF is predictable without prolonged delays. This information could be used to allow confident early discharge and identify patients whose deviation from normal may indicate complications.