Primary Fracture Research Articles

Underlying motivations hampering Flemish primary care physicians from overcoming the barriers in osteoporosis care: an EMR-facilitated clinical reasoning study

BackgroundOver half of the European population aged minimum 65 years presents with at least two chronic diseases. Attention towards these diseases exhibits disparities, with limited primary care physician (PCP) attention for osteoporosis. This was confirmed in a previous integrated osteoporosis care (IOC) project in which notable difficulties to enlist PCPs arose. Consequently, this study was initiated in Flemish PCPs for in-depth analysis of underlying mechanisms hampering PCPs to fully commit to osteoporosis care.MethodsA qualitative Electronic Medical Record (EMR)-facilitated clinical reasoning study was conducted. A semi-structured interview guide was employed to guide PCPs from reflections on their own patients to broader views regarding osteoporosis care. An inductive thematic analysis was performed using NVivo 12.ResultsThirteen PCPs were interviewed. They stated that osteoporosis patients often had complex (medical) profiles. PCPs emphasised the ongoing necessity for prioritisation within this context. This leads to a competition for PCP attention during consultations at three levels: i. between acute versus preventive care; ii. between primary fracture prevention and other preventive services and iii. between secondary fracture prevention and other preventive services; spanning eight areas of competition: disease significance, perceived impact, PCP awareness, the patient agenda, PCP competence, PCP support, perceived patient burden, and efficiency of care provision. Applicability of these areas of competition differed between levels.ConclusionThe intricate context in which PCPs operate, creates a competition for PCP attention leading to a lack of attention for fracture prevention. To preserve efforts in fracture prevention, areas of competition should be systematically addressed.Trial registrationApproval for the study has been provided by the Ghent University Hospital Ethics Committee (BC-09797).

Effects of Trapped Gas in Fracture-Pore Carbonate Reservoirs

Abstract Fracture-pore carbonate reservoirs exhibit strong microscopic heterogeneity and complex seepage characteristics, resulting in suboptimal oil-drive efficiency and development outcomes. Moreover, water channeling is often a serious problem in the development of fractured porous carbonate rocks, and the blockage of degassed bubbles in the throat is one of the reasons that cannot be ignored. In order to reveal the degree of influence of bubbles on waterflood sweep, this paper employs microfluidic technology to design three distinct chips, namely fracture-type, composite-type, and cave-type, to visually illustrate the influence of the gas phase on three-phase flow. A quantification method is established to analyze the variation characteristics of pore diameter utilization ratio in different types of carbonate reservoirs. Compared with water flooding experiments without the gas phase, the recovery factor of water flooding with the presence of the gas phase decreases by 0.6%, 3.4%, and 15.3% for three distinct chips, respectively. In fracture-type reservoirs, the main focus is on sealing the primary fracture seepage channel and mitigating the shielding effect of the gas phase on matrix utilization. For composite-type reservoirs, the primary objective is to seal fractures and eliminate the shielding effect of the gas phase. In cave-type reservoirs, the primary goal is to eliminate the sealing effect caused by the discontinuous gas phase within small pore throats.

Numerical Simulation of Hydraulic Fractures Breaking through Barriers in Shale Gas Reservoir in Well YS108-H3 in the Zhaotong Shale Gas Demonstration Area

Estimating the effectiveness of hydraulic fracturing in the context of the incrfease in the shale gas demand is of great significance for enhancing shale gas production, which aims to substantially reduce fossil energy consumption and CO2 emissions. The Zhaotong national shale gas demonstration zone has complex stress structures and well-developed fracture zones, and thus it is challenging to achieve targeted reservoir segment transformation. In this paper, we construct and optimize the geometry of hydraulic fractures at different pressures considering the upper and lower barriers in hydraulic fracturing simulation experiments and numerical modeling. The numerical simulation results show that the pore pressure exhibits a stepped pattern around the fracture and an elliptical pattern near the fracture tip. During the first time of injection, the pore pressure rapidly increases to 76 MPa, dropping sharply afterward, indicating that the fracture initiation pressure is 76 MPa. During the fracture propagation, the fracture length is much greater than the fracture height and width. The fracture width is larger in the middle than on the two sides, whereas the fracture height gradually decreases at the fracture tip in the longitudinal direction until it closes and is smaller near the wellbore than at the far end. The results revealed that the fracture width at the injection point reached the maximum value of 9.05 mm, and then it gradually decreased until the fracture width at the injection point dropped to 6.33 mm at the final simulation time. The fracture broke through the upper and lower barriers due to the dominance of the effect of the interlayer principal stress difference on the fracture propagation shape, causing the hydraulic fracture to break through the upper and lower barriers. The results of the physical simulation experiment revealed that after hydraulic fracturing, multiple primary fractures were generated on the side surface of the specimen. The primary fractures extended, inducing the generation of secondary fractures. After hydraulic fracturing, the width of the primary fractures on the surface of the specimen was 0.382–0.802 mm, with maximum fracture widths of 0.802 mm and 0.239 mm, representing a decrease of 70.19% in the maximum fracture width. This work yielded an important finding, i.e., the urgent need for hydraulic fracturing adaptation promotes the three-dimensional development of a gas shale play.

Can multiple miniplates improve the treatment of comminuted patellar fracture?

BackgroundWe have applied primarily multiple locking compression miniplates in treating multifragmentary, comminuted patellar fracture in combination with conventional fixation methods.MethodsMedical and radiologic data were retrospectively reviewed for the patients surgically fixated with locking compression miniplates in patellar fracture of AO/OTA 34-C3. The primary outcome was bone union at the final follow-up, and the secondary outcomes were functional outcomes and postoperative complications associated with the procedure. For the functional assessment, the Lysholm score, Tegner scores, and the knee range of motion was compared.ResultsA total of twenty patients with AO/OTA 34-C3 patellar fracture were included in the study with an average follow-up period of 15 months (range:11 ~ 18 months) between June 2018 and November 2021. Eleven male and nine female patients presented an average age of 57.15 years. The primary fracture union was seen in all twenty patients, and the average time to the union was 15.6 weeks on serial radiograph follow-up. All patients did not show any postoperative complications, such as fixation failure, infection, or revision operations. Postoperatively, all patients achieved an average range of motion of 130 degrees, and the Lysholm and Tegners scores showed an average of 90.4 and 5.0 at the final follow-up, retrospectively.ConclusionFixations with miniplates in comminuted patellar fractures can be a useful option for effective osteosynthesis due to their versatile, efficient, and low-profile nature.

Damage characteristics of pore and fracture structures of coal with liquid nitrogen freeze thaw

Liquid nitrogen (LN2) fracturing technology is a novel waterless fracturing technology that has significant potential for application in the development of coalbed methane. However, the changes in the microstructure after coal samples are treated with LN2 freeze thaw are poorly understood. Therefore, a combination of mercury intrusion porosimetry and micro-computed tomography (micro CT) was employed to investigate the evolution of pore and fracture structure of coal samples treated with LN2. The experimental results showed that the pore volume and average pore size of coal samples increase after LN2 freeze thaw. After 12 freeze thaw cycles, the change in pore volume of micropores and minipores of coal samples was not significant, while the pore volume of mesopores and macropores increased significantly before LN2 freeze thaw. The specific surface area of the pores in different size ranges of coal samples increases with the increase in the number of LN2 freeze thaw cycles; the structure of micropores and miniopores were damaged by thermal stress and frost heave force during LN2 freeze thaw; and the pore size gradually increases to form mesopores and macropores. Micro-CT images of coal samples after LN2 freeze thaw indicated the primary fractures of coal sample expanded and generated a large number of secondary fractures. The primary and secondary fractures are interconnected and ultimately form penetrated fracture enhancing the connectivity of fractures, enhancing the connectivity of the fracture structure. The key finding study is expected to provide a theoretical basis for LN2 fracturing.

Production induced fracture closure of deep shale gas well under thermo-hydro-mechanical conditions

Deep shale gas reservoirs have geological characteristics of high temperature, high pressure, high stress, and inferior ability to pass through fluids. The multi-stage fractured horizontal well is the key to exploiting the deep shale gas reservoir. However, during the production process, the effectiveness of the hydraulic fracture network decreases with the closure of fractures, which accelerates the decline of shale gas production. In this paper, we addressed the problems of unclear fracture closure mechanisms and low accuracy of shale gas production prediction during deep shale gas production. Then we established the fluid–solid–heat coupled model coupling the deformation and fluid flow among the fracture surface, proppant and the shale matrix. When the fluid–solid–heat coupled model was applied to the fracture network, it was well solved by our numerical method named discontinuous discrete fracture method. Compared with the conventional discrete fracture method, the discontinuous discrete fracture method can describe the three-dimensional morphology of the fracture while considering the effect of the change of fracture surface permeation coefficient on the coupled fracture–matrix flow and describing the displacement discontinuity across the fracture. Numerical simulations revealed that the degree of fracture closure increases as the production time proceeds, and the degree of closure of the secondary fractures is higher than that of the primary fractures. Shale creep and proppant embedment both increase the degree of fracture closure. The reduction in fracture surface permeability due to proppant embedment reduces the rate of fluid transfer between matrix and fracture, which has often been overlooked in the past. However, it significantly impacts shale gas production, with calculations showing a 24.7% cumulative three-year yield reduction. This study is helpful to understand the mechanism of hydraulic fracture closure. Therefore, it provides the theoretical guidance for maintaining the long-term effectiveness of hydraulic fractures.

Supporting Fracture Liaison Services in England and Wales: A role for pharmacists?

Abstract Introduction Fracture Liaison Service (FLS) deliver secondary fracture prevention to adults aged 50 years and over. Performance is measured against ten benchmarks [B1-10]: cases identified [B1], spine fractures [B2], assessment within 90 days [B3], dual x-ray absorptiometry (DXA) within 90 days [B4], falls risk assessment [B5], bone treatment recommended [B6], strength and balance by 16 weeks [B7], 16-week follow-up [B8], treatment by first follow-up [B9] and 1-year drug adherence check [B10]. Each indicator has standards for meeting >80% of target (green), 50-79% (amber) and <50% (red). For Spine fractures [B2], >20% identified denotes green, amber for 11-19% and red for <10%. For bone treatment recommended [B6], green denotes >50% and red <50%. Audit data is uploaded to the Fracture Liaison Service Database (FLS-DB).1 Aim To establish whether FLSs meet performance targets and identify how pharmacists could support the service. Methods This work was done as part of a PhD project at the University of Nottingham looking at how pharmacists could improve osteoporosis medication adherence. Therefore, an existing service which encounters people with osteoporosis (FLS) was investigated to see if it required support. Approval reference: 017-2021. National averages for benchmarks were analysed to see if targets were being met over a 5-year period (2016-2020).1 The Royal Osteoporosis Society (ROS) Clinical Standards for FLSs2 were reviewed to identify areas where pharmacists could support the service. Findings were reviewed by two authors of the Clinical Standards for FLSs. Results Less than half (49%) of FLSs’ in England and Wales submitted data consistently between 2016-2020. Of those who submitted, only recommendations to initiate bone treatment [B6] met the required target (>50% of patients) in 2018 (53%), 2019 (52.4%) and 2020 (52.9%). However, B9: Treatment by 1st follow-up targets were not met. Possibly due to the lack of data for pharmacy support, the ROS Clinical Standards for FLSs do not mention pharmacists. Staffing data shows no pharmacists employed at FLSs. However, the research team identified eleven areas where implementation of referral pathways between community pharmacy (CP) and FLSs could support patient management. These were related to identification of people aged over 50 years with a fragility fracture (1.1), investigations of fragility fracture risk within 12 weeks of a fracture diagnosis (2.1, 2.2), provision of information to patients and healthcare professionals (3.1, 3.2, 3.3, 3.4), interventions such as drug treatment initiation, reviews, referrals to falls prevention services (4.1, 4.2, 4.3) and integration of the wider healthcare system to ensure long term management of osteoporosis (5.1). Multi-disciplinary working and incorporating primary and secondary fracture prevention and medicines review outcomes,3 would help inform transfer of care on this pathway. Discussion/Conclusion FLSs’ needs support to ensure benchmark targets are met especially related to anti-osteoporosis medication initiation and adherence. Due to their expertise, pharmacists could support the FLS, particularly with treatment initiation and adherence related monitoring. Implementation of a two-way referral pathway between FLSs’ and community pharmacy could help improve patient outcomes. Limitation: There is missing data as not all FLSs upload to the FLS-DB.

Experimental investigation on mode I fracture characteristics of Longmaxi formation shale after cyclic thermal shock and high-temperature acid etching treatments

Fracture toughness is a key parameter for shale hydraulic fracturing design, which directly affects the fracture initiation pressure. In this paper, the influence of cyclic thermal shock and high-temperature acid etching on the Mode I fracture of Longmaxi Formation shale was investigated. The crack propagation was obtained by using acoustic emission (AE) and digital image correlation (DIC) techniques. Meanwhile, the fracture surface morphology and microstructure of the specimens were analyzed using white light interferometer and scanning electron microscope (SEM). The experimental results demonstrate that cyclic thermal shock severely degrades the nominal strength and fracture toughness of shale. The average fracture toughness is found to be only 0.67 MPa·m0.5, which accounts for a reduction of 25.9 %. AE analysis reveals that microfracture is the dominant mechanism, with the highest amplitude of AE source only 78 dB. The critical strain value of the fracture propagation zone (FPZ) is determined to be 1.35 ‰, and SEM images indicate that along-crystal fracture is the primary fracture mechanism. On the other hand, the shale specimen subjected to high-temperature acid-etching treatment exhibits an average fracture toughness of 0.86 MPa·m0.5, with the AE source amplitude reaching 86 dB. The critical strain value of the FPZ was measured to be 2.38 ‰. The fracture surface appears smooth and is mainly characterized by perforated-crystal rupture. The findings of this study not only enhance our understanding of shale mode I fracture toughness but also provide valuable insights for optimizing process parameters to reduce initiation pressure in deep shale formations.

Novel nomogram for predicting paradoxical chest wall movement in patients with flail segment of traumatic rib fracture: a retrospective cohort study

Flail chest is a severe injury to the chest wall and is related to adverse outcomes. A flail chest is classified as the physiologic, paradoxical motion of a chest wall or flail segment of rib fracture (RFX). We hypothesized that patients with paradoxical chest wall movement would present different clinical features from patients with a flail segment. This retrospective observational study included patients with blunt chest trauma who visited our level 1 trauma center between January 2019 and October 2022 and were diagnosed with one or more flail segments by computed tomography. The primary outcome of our study was a clinically diagnosed visible, paradoxical chest wall motion. We used the least absolute shrinkage and selection operator (LASSO) logistic regression model to minimize overfitting. After a feature selection using the LASSO regression model, we constructed a multivariable logistic regression (MLR) model and nomogram. A total of five risk factors were selected in the LASSO model and applied to the multivariable logistic regression model. Of these, four risk factors were statistically significant: the total number of RFX (adjusted OR [aOR], 1.28; 95% confidence interval [CI], 1.09–1.49; p = 0.002), number of segmental RFX including Grade III fractures (aOR, 1.78; 95% CI, 1.14–2.79; p = 0.012), laterally located primary fracture lines (aOR, 4.00; 95% CI, 1.69–9.43; p = 0.002), and anterior–lateral flail segments (aOR, 4.20; 95% CI, 1.60–10.99; p = 0.004). We constructed a nomogram to predict the personalized probability of the flail motion. A novel nomogram was developed in patients with flail segments of traumatic RFX to predict paradoxical chest wall motion. The number of RFX, Grade III segmental RFX, and the location of the RFX were significant risk factors.

Analysis of changes in serum high t-PINP/β-CTX ratio and risk of re-fracture after vertebral osteoporotic fracture surgery.

This study's aim was to investigate the expression changes of total type I procollagen amino-terminal peptide (t-PINP) and type I collagen C-terminal peptide (β-CTX) in serum after vertebral osteoporotic fracture surgery and the clinical value of predicting the risk of refracture. The clinical data of 100 patients with vertebral osteoporotic fractures treated in our hospital from January 2019 to January 2020 were retrospectively analyzed, and the patients were divided into the control group (patients without re-fracture, n = 68) and the observation group (patients with re-fracture, n = 32) according to whether they had re-fracture at 2-year follow-up. The risk factors of postoperative re-fracture were analyzed using Multivariate logistic regression analysis. The serum contents of t-PINP, β-CTX, osteocalcin (BGP), and calcium (Ca) were measured. Bone mineral density (BMD) was measured by bone densitometer. The correlation between the t-PINP/β-CTX ratio and the bone metabolic index was analyzed by Pearson correlation. The area under the curve (AUC), sensitivity, and specificity of t-PINP/β-CTX in predicting the risk of re-fracture were determined by the receiver operating characteristic (ROC) curve. There was a significant difference in age, the number of vertebral bodies with initial fracture, and whether there was leakage of bone cement between the two groups (p < 0.05). Age, the number of vertebral bodies with primary fracture, and the leakage of bone cement were risk factors affecting re-fracture after operation (p < 0.05). Compared with those in the control group, the level of t-PINP and the ratio of t-PINP/β-CTX were higher, and the β-CTX level was lower in the observation group (p < 0.05). The BGP level was higher, and the levels of BMD and Ca were lower in the observation group than those in the control group (p < 0.05). Pearson correlation analysis showed that t-PINP had a positive correlation with BGP (r = 0.222, p < 0.05). β-CTX was positively correlated with BMD and Ca (r = 0.230, 0.269, p < 0.05). The ratio of t-PINP/ β-CTX was negatively correlated with BMD and Ca (r = -0.621 and -0.660, p < 0.05), but positively correlated with BGP (r = 0.517, p < 0.05). ROC curve analysis showed that the AUC of t-PINP, β-CTX, and the ratio of t-PINP/β-CTX in predicting the risk of re-fracture after vertebral osteoporotic fracture surgery was 0.724, 0.736, and 0.838, respectively. The t-PINP/β-CTX ratio was significantly correlated with the bone metabolic indexes in patients with vertebral osteoporotic fractures. The detection of the changes in its index can help predict the risk of postoperative re-fracture, providing a new idea for clinical assessment of the risk of postoperative re-fracture.

Astudy of fracture lines distribution characteristics in complete articular fractures of the patella.

The objective of this study was to unveil the characteristics of fracture lines distribution and explore its clinical significance of complete articular fractures of the patella. A consecutive series of image data from 88 patients with complete articular patella fractures were retrospectively included. Three-dimensional reconstruction images of the patella fractures were created and collected. Subsequently, these reconstructed images were visually overlaid onto a standard anterior and posterior patella template. The fracture lines were then identified, traced onto the template, and utilized to generate patella fracture maps. Furthermore, the incidence rate of patella fracture lines involving the distal pole was analyzed. The maps depict the fracture lines of complete articular patella fractures. For simple and complex patella fractures, the primary fracture lines primarily converge within the Middle and Lower regions, exhibiting a transverse pattern. Conversely, the primary fracture lines in comminuted patella fractures are randomly dispersed across the patella. Examining the maps, approximately 63.6% (56/88) of complete articular patella fractures exhibited involvement of the distal pole in the anterior view, while 48.9% (43/88) displayed distal pole fractures in the posterior view. The incidence of distal pole injury increased progressively with the severity of patella fractures. The patterns and distribution of fracture lines in cases of complete articular patella fractures are prominently illustrated on the constructed fracture maps. Familiarity with these common characteristics of complete articular patella fracture, especially with the distal pole injury, can aid surgeons in developing preoperative planning, executing surgical strategies effectively, and reducing inappropriate treatment.

Experimental study on the influence of ultrasonic excitation duration on the pore and fracture structure and permeability of coal body

The study aims to explore the effect of ultrasonic duration on the pore structure and seepage characteristics of coal. Herein, we adopted a self-developed ultrasonic excitation experiment system using low-field nuclear magnetic resonance (NMR) technology and NM-4B non-metallic ultrasonic wave velocity detector. The study investigated NMR relaxation time T2 patterns and the number of pores of each size, internal structural damage, and seepage characteristics of the coal body before and after ultrasonic fracturing. Based on the Warren-Root model, the permeability model of coal under ultrasonic fracturing was established, revealing the changing law of ultrasonic fracturing at different times on the change of pore scale, connectivity, and nuclear magnetic permeability of the coal body. The mechanism of ultrasonic fractured coal body evolution at different times was clarified. The results showed that the ultrasonic fracturing at different times improved the number and volume of all size pores in the coal body, expanded primary fractures, and developed newborn fractures. The rate of change in pore size, porosity, wave velocity, and coal permeability had a linear relationship with the fracturing time. The growth rate of seepage pore volume proportion was positively correlated to the decreased rate of adsorption pore volume proportion. The fracturing duration leads to the interconnection of micropores within the coal body, forming medium and large pore fractures. This transformation between pores and fractures enhances the pore structure and seepage characteristics of the coal body. The coal rock permeability model can be used to calculate the permeability of a coal body, which follows the same change law as nuclear magnetic permeability. When evaluating the index using absolute and relative errors, the range of relative error is 0.97%–7.91%. The error variation range is small, indicating that the established model can effectively reflect the change law of porosity and permeability of the coal body responding to ultrasonic fracturing. The ultrasonic fracturing rendered the ultrasonic cavitation takes micropores as fracturing units, developed pores of all sizes, connected closed pores, increased free fluid space proportion, and improved the coal permeability.

Management of complications of mega-implants following treatment of primary and periprosthetic fractures of the lower extremities

In recent years, indications for implanting mega-implants were established in managing major bone defects linked to revision arthroplasty due to loosening, periprosthetic fractures, re-implantation following periprosthetic joint infection, non-union following fractures as well as complex intraarticular primary fractures. This study was conducted to discuss and analyze the strategy of diagnosis and management of complications following the use of mega-implants in treating primary and periprosthetic fractures of the lower extremities. This is a monocentric retrospective study. Patients aged ≥ 18 years who underwent implantation of a megaendoprosthesis due to periprosthetic or primary fractures of the lower extremity between January 2010 and February 2023 were identified from the authors’ hospital information system. We identified 96 patients with equal numbers of fractures (71 periprosthetic fractures and 25 primary fractures). 90 cases out of 96 were investigated in this study. The drop-out rate was 6.25% (six cases). The average follow-up period was 22 months (1 to 8 years) with a minimum follow-up of 1 year. The diagnosis of complications was provided on the basis of subjective symptoms, clinical signs, radiological findings and laboratory investigations such as C-reactive protein, leucocyte count and the microbiological findings. The indications for implantations of modular mega-implants of the lower extremities were periprosthetic fractures (65 cases/72.22%) and primary fractures (25 cases/27.78%). Pathological fractures due to malignancy were encountered in 23 cases (25.56%), in one case due to primary tumor (1.11%) and 22 cases due to metastatic lesions (24.44%). Two cases (2.22%) presented with primary intraarticular fractures with severe osteoporosis and primary arthrosis. In all cases with malignancy staging was performed. Regarding localization, proximal femur replacement was encountered in 60 cases (66.67%), followed by distal femur replacement (28 cases/31.11%) and total femur replacement (2 cases/2.22%). The overall complication rate was 23.33% (21 complications in 21 patients). The most common complication was dislocation which was encountered in nine cases (10%), all following proximal femoral replacement (9 cases out of 60, making 15% of cases with proximal femoral replacement). The second most common complication was infection (six cases, 6.67%), followed by four aseptic loosenings (4.44%), further intraoperative periprosthetic fracture in one case (1.11%) and a broken implant in one case (1.11%). We noticed no cases with wear and tear of the polyethylene components and no cases of disconnections of the modular components. Mega-endoprostheses enable versatile management options in the treatment of primary and periprosthetic fractures of the lower extremities. The rate of complications such as loosening, implant failure, dislocation and infection are within an acceptable range in this preliminary analysis. However, implantation of mega-endoprostheses must be strictly indicated due the limited salvage options following surgery.

Fractographical Characterization of Jute Fibre Reinforced Paper Composite Subjected to Drop Test

Plastic bags are one of the most widely used packaging materials in industries. Lower production cost, lightweight and high strength envisage its use in food packaging, carrier, and transportation industries. However, these plastic bags are non-biodegradable and cause serious water and soil pollution. It is one of the most thrust areas of research to overcome this problem in the current world. In the present investigation, fabrication, and characterization of an environmentally friendly and biodegradable "jute fibre reinforced paper composite" and "reinforcement free paper laminate" subjected to drop test were done. The standard procedure of the "MIL-STD-810G 516.6" drop test was followed. The adhesion between the matrix (paper) and reinforcement (jute fibre) was produced by applying a chemical-free adhesive made of flour and water. There were four different types of samples: single paper (SP), reinforcement-free paper laminate (RFPL), single-layer jute fibre reinforced paper composite (SLJPC), and double-layer jute fibre reinforcement paper composite (DLJPC). The microstructural characterization of the fractured surface after the drop was done using a scanning electron microscope operated at a voltage of 20 kV. The DLJPC samples had the maximum density and envisage drop-strength of 7 times as compared to the SP samples having the lowest density. The drop-strength exhibited linear regression with density for all the samples. The microstructure of the as-received matrix showed a non-homogeneous distribution of fibres along with micro-voids which were susceptible sites for the fracture. Unlike as-received matrix fibres distribution, the reinforcement fibres were aligned in two mutually perpendicular directions which leads to its strengthening. Hence, it can be said that the non-uniform structural properties envisaged by the as-received matrix can be compensated by uniformly distributed structural properties of the as-received reinforcement when both come together as a composite. The primary fracture mechanism of SP samples exhibited fibre breaking along with a few fibres' delamination. However, in the case of the RFPL sample, the nature of adhesion applied was capable to hold both the interfaces and the primary fracture mechanism was fibre breaking. It is suggested that the adhesive applied transmitted load through the interfaces. Unlike SP sample, the RFPL sample exhibited some adhesive pull-off. The fractured surface of the SLJPC sample showed that the matrix did not subject to fracture, however, reinforcement did fracture hence the load was transferred from matrix to reinforcement followed by a rupture of the reinforcement. Therefore, the primary fracture mechanism for the SLJPC sample was reinforcement rupture. The DLJPC sample showed a delamination of matrix and reinforcement.

Research on the evolution and height prediction of WCFZ in shallow close coal seams mining

Based on the mining conditions of shallow close coal seams in the Jurassic coalfield of northern Shaanxi, in order to explore the evolution and development height prediction of water-conducting fracture zone (WCFZ), combining with measured statistical analysis, physical simulation, numerical calculation, and theoretical analysis, the evolution of mining-induced fractures and the development characteristics of WCFZ are analyzed, and the development height predicting method of WCFZ in shallow close coal seams mining is proposed. The results show that in shallow single coal seam mining, during the stage of incritical mining, the height of the WCFZ increases in a “jumping” pattern with the main roof periodic caving. After critical mining, it is basically stable. Its development height is positively correlated with the mining height. The ratio of development height to mining height is generally 20–30, and the change is not significant with the mining height, overall, the distribution of the WCFZ is “saddle shaped”. Based on close distance coal seams repeated mining, the primary fractures act as activation development when the interburden broken completely, the development of WCFZ at the mining boundary is significantly intensified, and ratio of the height to mining height in repeated mining is obviously lower than that in single seam mining, which is generally 18–25. The traditional empirical formula cannot be applied to the development prediction in shallow close coal seams mining, with an error of 10–50%. Considering the mining height, interburden thickness, and roof caving characteristics, the development height predicting method of WCFZ in shallow close coal seams mining is proposed. Compared with measured results, the calculation error is basically within 15%, which has good prediction accuracy, The research results can provide a theoretical basis for predicting the height of WCFZ in shallow close coal seams mining in the Jurassic coalfield of northern Shaanxi.

Primary and Periprosthetic Distal Femur Fractures in Older Adults: No Difference in 12-Month Mortality and Patient-Reported Outcomes.

To compare fracture incidence, mortality, and patient-reported health outcomes at 6 and 12 months postinjury between primary and periprosthetic distal femur fractures in older adults. A registry-based cohort study was conducted including all adults 70 years of age or older registered by the Victorian Orthopaedic Trauma Outcomes Registry who experienced a primary or periprosthetic distal femur fracture between 2007 and 2017. Outcomes included mortality and health status (Three-Level European Quality of Life-Five Dimensions Scale [EQ-5D-3L]) collected at 6 and 12 months postinjury. All distal femur fractures were confirmed by radiological review. Multivariable logistic regression was conducted to report associations between fracture type and mortality and health status. A final cohort of 292 participants was identified. Overall mortality for the cohort was 29.8%, and no significant differences were found in mortality rate or EQ-5D-3L outcomes between fracture types (ie, primary vs. periprosthetic). A large proportion of participants reported problems across all EQ-5D-3L domains at 6 and 12 months postinjury, with slightly worse outcomes in the primary fracture group. This study reports high mortality and poor 12-month outcomes in an older adult cohort with both periprosthetic and primary distal femur fractures. Given these poor outcomes, fracture prevention and a greater focus on long-term rehabilitation is needed in this cohort. In addition, the involvement of an ortho-geriatrician should be considered as a routine component of care. Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Contextual relationship between mechanical heterogeneity and dyking: constraints from magma emplacement dynamics of the ca. 2.21 Ga Anantapur–Kunigal mafic dyke swarm, Dharwar Craton, India

AbstractMafic dykes are typically emplaced through primary hydraulic fracturing of undeformed crust or may make use of pre-existing crustal inhomogeneities, representing the plumbing systems of a large igneous province. The Eastern Dharwar Craton has dense exposures of several generations of Paleoproterozoic mafic dyke swarms ranging from ca. 2.37 Ga to ca. 1.79 Ga. Herein, using anisotropy of magnetic susceptibility fabric data of mafic dykes and associated host granites, the emplacement systematics of the NW- to W-trending ca. 2.21 Ga Anantapur–Kunigal dyke swarm, displaying a radiating geometry, have been studied to understand magma flow dynamics. A low-angle relationship between the silicate and opaque fabrics and good correlation with magnetic lineation, identified via petrographic studies and shape preferred orientation analyses of multiple oriented thin sections, suggest a primary flow-related magnetic anisotropy for the studied dyke samples. The classic subparallel relationship between the trend of the dyke planes and magnetic fabric of the associated host granites suggests that the radiating geometry of the ca. 2.21 Ga dyke swarm was supported by a favourable pre-existing structural grain of the country rock. We interpret the magma for the studied dyke swarm was fed laterally from a distant plume. It was emplaced as laterally propagating primary dyke fractures as well as injected into the pre-existing subparallel crustal inhomogeneities. Corroborating all these inferences, a detailed emplacement model for ca. 2.21 Ga Anantapur–Kunigal dyke swarm is also proposed.

Research and Implementation of Three-Dimensional Spatial Information Characterization and Visualization of Fractures in Deteriorated Sandstone

Primary fractures significantly impacted the stability of surrounding rock in underground projects. Therefore, it is vital to find a solution for the problem of performing a non-destructive detection of rocks and extracting the internal three-dimensional (3D) data field of rocks for visualization analysis. To address this problem, this paper proposed a method of 3D reconstruction for complex cracks in deteriorated sandstone and developed a program based on MATLAB. This work carried out image recognition on the CT scan images of deteriorated sandstone, then implemented a surface reconstruction technique based on object cross-section information, a contour reconstruction technique based on object contour information, a point cloud reconstruction technique for extracting point cloud data of internal cracks in deteriorated sandstone, and a Graphical User Interface (GUI) control system that combines these three reconstruction techniques. The results showed that the 3D reconstruction techniques and the GUI control system proposed in this paper were capable of precisely marking the location of the cracks on a 3D coordinate system and accurately describing their shape with a vector. With only 10 CT scan images, the point cloud reconstruction technique constructed the digital core, and the digital core can quantitatively characterize the influence of primary fractures on the stability of surrounding rock. Additionally, the calculated results of the proposed method were very close to that of Avizo. This method realized the visualization and quantitative characterization of the internal structure of rocks and offered a model for analyzing the stress-fracture-seepage field change during excavation.

Study on mechanical properties and microscopic damage mechanism of tight sandstone reservoir under uniaxial compression

Due to the characteristics of low porosity, low permeability and serious anisotropy in tight reservoirs, it is difficult for conventional hydraulic fracturing theory to accurately guide the efficient exploitation of tight reservoirs. It has been shown that the reservoir rock mechanical properties are the key factor impacting the fracturing effect, but the current research on the damage properties of tight reservoir rocks is not comprehensive enough. Therefore, in order to improve the fracturing theory of tight reservoirs, this paper first explores the evolution mechanism of rock fractures through uniaxial compression experiments. Secondly, based on the particle discrete element method, the damage and failure process of tight sandstone under uniaxial compression is simulated from the microscopic scale. The test results show that the rock failure mainly includes tensile failure, shear failure, and tensile-shear failure; Internal micro-fractures will interconnect during rock destruction to form primary fractures through the rock mass, while secondary micro-fractures will also be generated. The numerical simulation results show that when the rock is subjected to tensile-shear failure, with the increase of load, tensile micro-fractures are mainly produced in the specimen, accompanied by a few shear fractures. Under the joint action of shear failure and tensile failure, V-shaped cracks are easily formed in rock. The tensile strength of rock is mainly affected by the microscopic tensile strength, and the cohesive force, modulus, stiffness ratio, friction coefficient and friction angle have significant effects on the compressive strength of rock. Therefore, a reasonable choice of microscopic parameters can realistically simulate the compression-tensile strength ratio of the rock. The research results of this paper can provide the theoretical basis of rock mechanics for the efficient exploitation of tight reservoirs.

Numerical simulation of proppant transportation and placement in several complex structure fractures of a shale reservoir using a CFD approach

In the experimental simulation of proppant transportation in the complex fractures of shale reservoirs, the influence of many factors such as partial fracture parameters are often ignored, which cannot fully reflect the proppant transportation in the real situation. The Euler model and turbulence model were performed to numerically investigate proppant transportation and placement using the computational fluid dynamics (CFD) method, and was verified with experimental results. The formation process of proppant banks in branched, staggered, and different types of combined fractures was analyzed. The effects of the position, width, included angle of the secondary fracture, and fracture structure type on proppant transportation and placement were discussed. The simulations indicate that the proppant bank formation in the primary fracture is considered to occur in four stages and different from three stages in the secondary fractures. The proppant bank located at the node between the primary and the secondary fractures possesses good continuity, and the propagation of the proppant bank in the secondary fracture is closely related to the proppant bank state at the node in the primary fracture. The equilibrium time of the proppant bank in the secondary fracture and the primary fracture is related to the position of the secondary fracture. The total placement rate and settlement volume of proppant in the symmetrical oblique fracture is the highest for the same oblique angles, and the proppant bank morphology in the orthogonal fracture has good symmetry, improving the reliability of the fracturing design and the post-fracturing evaluation in shale reservoirs.