Fracture behaviors of HVFA-SCC mixed with seawater and sea-sand under three-point bending

This paper aims to study the fracture behaviors of high-volume fly ash-self-compacting concrete (HVFA-SCC) mixed with seawater and sea-sand (SWSS) or freshwater and river sand (FWRS). Three-point bending test were performed on 24 notched beams fabricated with varying in replacement ratio of fly ash (0%, 30%, 50%, and 70%) and the type of water and sand (SWSS and FWRS). The initial and unstable fracture toughness of these test specimens are determined by the double- K fracture model. The effect of fly ash replacement ratio and type of water and sand on the fracture parameters is analyzed and discussed. In addition, the cohesive fracture toughness of all the test specimens is calculated by using Gauss–Chebyshev integral method and the weight function method based on the bilinear tensile softening curve given in CEP-FIP Model Code. A comparison of fracture toughness parameters of determined from the experimental approach and analytical approaches is presented in these SCC specimens. Results show that SCC mixed with SWSS replacing FWRS can improve the unstable fracture toughness and fracture energy, and decrease its brittleness behavior. The cohesive fracture toughness of SWSS-SCC specimens is underestimated by these analytical methods based on the tensile softening curve given in CEP-FIP Model Code.

Severe Thoracic Vertebral Spine Injury as a Complication of Component of Cardiopulmonary Resuscitation

Chest compression has been a component of cardiopulmonary resuscitation (CPR) since 1960. Performance of high-quality CPR is critical for survival; however, chest compressions are traumatic and may result in injuries such as rib and sternal fractures. Spinal fractures have rarely been reported. We present a case of a 69-year-old male who suffered a cardiac arrest at home. He underwent 16 minutes of CPR with manual chest compressions, and no electrical shock and medications with return of spontaneous circulation (ROSC). Computed tomography scan showed unstable fracture of T9-T10. The patient was transferred to our Level I trauma center for continued post-arrest management and neurosurgical evaluation. An MRI confirmed the unstable spinal fracture which would have required surgical stabilization. The patient remained comatose, thus he was transitioned to comfort measures and expired. Spinal injuries following CPR are rare but should be considered in the post-arrest management stage. Computed tomography scan is the ideal screening modality.

Influence of Graphite Powder on the Mechanical and Acoustic Emission Characteristics of Concrete

In this paper, uniaxial compressive strength (UCS) test and three-point bending (TPB) test, together with an acoustic emission (AE) system, were performed to investigate the mechanical properties and AE characteristic changes of concrete with different graphite powder (GP) content. The results show that: (1) Poor adhesion and low interlocking of graphite with cement stone increase the initial defects of concrete, reducing its elastic modulus and the cyclo-hoop effect, and thus weakening the compressive strength. (2) For concrete with a low graphite content, the second sharp rise in ringing counts or energy released during the compressive process can be regarded as a failure alarm. However, as GP content increases, the second sharp rise fades away, while the first sharp rise becomes more visible. At high GP content, the first sharp rise is better for predicting failure. (3) The initial defects caused by GP significantly lower the initial fracture toughness, but its bridging effect greatly increases the critical crack mouth opening displacement and thus significantly enhances the unstable fracture toughness of concrete, by up to 9.9% at 9% GP content. (4) In contrast to compressive process, the sharp increase in AE signals preceding failure during the fracture process cannot be used to predict failure because it occurs too close to the ultimate load. However, as GP can significantly increase the AE signals and damage value in the stable period, such failure precursor information can provide a safety warning for damage development.

Risk decreasing of water waste through spontaneous fracturing in injectors by integrated well-testing and production logging

Background. When creating an effective reservoir pressure maintenance system, unstable spontaneous hydraulic fractures can be created in injection wells. This can both negatively and positively affect hydrocarbon production. First, fracture improves reservoir connectivity, which increases injection efficiency. On the other hand, unstable fractures can cause behind-the-casing flows and unproductive injection into off-target layers or fingering. Goal. The paper is devoted to the analysis of well testing (PTA) and production logging (PLT) improvement for the diagnosis of unstable fractures in injection wells. Materials and methods. The analysis is based on the results of modeling the pressure in the reservoir system, describing the penetration reservoirs by an unrestricted conductivity unstable fracture. It is taken into account that the fracture can cross both the perforated formation and the thickness not penetrated by the perforation, and can grow with increasing overbalance. The modeling results made it possible both to assess the potential informative capabilities of well testing and to substantiate recommendations for the practical use of the obtained results. Conclusions. The proposed approaches to the technology of well testing and production logging and the interpretation of their results make it possible to estimate the additional thicknesses of the reservoirs connected by the spontaneous hydraulic fracturing to injection, the proportion of nonproductive injection in the total volume of the well. The research technology used by the authors is based on continuous measurements of pressure and flow rate during cyclic change of pressure and assessment of the effective transmissibility of the formation system at different heights of unstable fractures. The role of the PLT is to determine the effective production thickness of the reservoirs. When assessing the injectivity profile when penetrating the injector with the spontaneous hydraulic fracturing, the key role belongs to non-stationary temperature logging. In this case, it is necessary to take into account the specific features of temperature relaxation in the wellbore after the injection cycle, related to hydraulic fracturing, primarily the increase in the relaxation rate with increasing fracture length.

A comparative study of Dynamic Hip Screw and Proximal Femoral Nail in the management of Intertrochanteric Fractures of the Femur

Introduction: Intertrochanteric fractures account for approximately half of the hip fractures in the elderly because of the osteoporotic nature of the bone. There are various modalities to treat these fractures. The objective of this study was to compare and evaluate the clinical and radiological outcome of intertrochanteric femur fracture treated with Dynamic hip screw (DHS) and proximal femoral nail (PFN). Methods: This study was conducted at Nepalgunj medical college, Department of orthopedics Nepalgunj over a time span of two years. A total of 52 patients were included and randomized into Dynamic hip screw (n=26) and Proximal femoral nail (n=26) group. Patient’s demographic details, perioperative findings, radiological findings and follow up findings were recorded. The results were evaluated and compared. Results: The mean age in our study was 57.63 years. Trivial fall was the most common mode of injury. There was significantly higher intraoperative blood loss in the DHS group. Radiological union and functional outcomes were similar overall, but in case of unstable fracture functional outcome was clinically better in PFN group. Conclusion: From our study we concluded that PFN has better outcome in case of unstable intertrochanteric fractures, however in stable fracture also it has distinct advantage over DHS.

Long-term outcomes of distal locking in extracapsular fractures treated with trochanteric Gamma3 nails

Background Few publications have assessed long-term results of distal locking of short endomedullary nails for extracapsular hip fracture. Virtually all of them focus on immediate differences. Criteria for the use of static or dynamic locking are unclear in most nailing systems, and use is advised in unstable fracture patterns or with risk of bell-clapper effect, but often influenced by the “orthopaedic school”. Materials and methods This is a historical cohort study on patients diagnosed and operated in 2014 and followed up until endpoint, considered as consolidation or major complication, plus evaluation of overall long-term survival. They were categorised as static distal locking (ST) or dynamic distal locking (DN). Both are comparable, except for all stable pre-operative classifications, Fracture Mobility Score (FMS) at discharge, and immediate post-operative loading, all of which were in favour of DN. Results Consolidation took place in > 95% of patients, with a non-statistically significant delay trend in ST. Less than 6% in both ST and DN had major complications, with no differences. Most cases suffered early cut-out. Significant fracture collapse was the most frequent minor complication. There were more statistically significant minor and total complications in ST. Infection, without differences, can precede cut-out. Lateral thigh pain was similar and could be related to back-out. In DN, 21.1% of cases were truly dynamised. We did not find differences in mobility or in long-term survival. Conclusions Any type of distal locking seems to be safe for consolidation, despite a slightly longer consolidation time in static locking. Early cut-out was the main complication, while others were very infrequent, which is an advantage over helical blade devices. There was a higher rate of minor and overall mechanical complications in ST, but infection and lateral thigh pain were similar. Most non-traumatic mechanical complications occurred around 5–6 weeks. About one in five of the DN truly dynamised, with all cases occurring before 8 weeks. Mobility until endpoint and overall long-term survival were not influenced by the locking mode used. Level of evidence Therapeutic study, level 2b.

RILEM Standard: testing methods for determination of the double-K criterion for crack propagation in concrete using wedge-splitting tests and three-point bending beam tests, recommendation of RILEM TC265-TDK

In this recommendation, standard testing methods for determination of the double-K criterion for Mode I crack propagation in concrete using wedge-splitting tests and three-point bending beam tests are specified for the fracture parameters of the initial cracking toughness $$K_{Ic}^{ini}$$ K Ic ini and the unstable fracture toughness $$K_{Ic}^{un}$$ K Ic un . Along with the recommendation of the standard testing methods, the theoretical background of the double-K criterion, the calculation methods and the results of round-robin testing for determining the double-K fracture parameters are presented in technical reports [1, 2]. The recommendation of the standard testing methods includes geometry for specimens, fabrication of specimens, testing machine, load transmission system and supports, measuring instruments, determination of initial cracking load Pini, determination of measured maximum load Pmax and initial compliance ci, calculation methods for wedge-splitting test and three-point bending beam test, as well as the testing results and testing report forms. According to these methods, the measured fracture parameters of double-K criterion can be used to describe the onset of cracking, and the onset of unstable cracking or failure for predicting crack initiation, structure failure and crack stability in concrete structures.

AO/OTA 31A2 and 31A3 Intertrochanteric Fractures Managed by Proximal Femoral Nail Antirotation (PFNA)

Aim: To study the clinical and radiological outcome of unstable intertrochanteric fracture AO/OTA 31A2, 31A3 fixed by proximal femoral nail antirotation Study design: Descriptive cross sectional study. Place and duration of study: Department of Orthopedic Surgery and Traumatology, Pir Abdul Qadir Shah Jilani Institute of Medical Sciences, Gambat, Sindh from 1st January 2016 to 31st December 2019. Methodology: Forty four cases having intertrochanteric fracture AO/OTA 31A2, 31A3 with age ranging from 18 year to 55 year of either gender were selected; patients having close fracture, who were willing were included in the study, while patients older than 55 year and younger than 18 year, AO/OTA 31A1 fracture, open fracture, bilateral injuries, smoker, alcoholic, drug addicted, poly-trauma, pathological fracture and history of poor compliance, psychiatric disease were excluded. Results: There were 26(59.09%) males and 18(40.91%) females with mean age was 41.3±7.7 years. Regarding classification; AO/OTA 31A2 were 33 (75%), and 31A3 were 11 (25%). Mean time for union was 18.5±3.55 weeks. The average time of follow-up was 48.5±6.6 weeks. Harris Hip Score was excellent (90-100) in 31(70.45%), good (80-89) in 7(15.91%), fair (70-80) in 3 (6.81%) and poor (<70) in 3 (6.81%). Conclusion: Intramedullary device proximal femoral nail antirotation can be labelled as implant of choice for unstable intertrochanteric fractures AO/OTA 31A2, 31A3, with fruitful clinical and radiological outcomes, and with fewer complications. Hip Harris score was excellent-good in 86% of the patients. Key words: Proximal femoral nail antirotation (PFNA), AO/OTA 31A2, 31A3, Intertrochanteric, unstable fracture

Clinical value of MRI in evaluating and diagnosing of humeral lateral condyle fracture in children

Background Humeral lateral condyle fractures (HLCFs) are common paediatric fractures. Radiographs are hard to accurately evaluate and diagnose the damage of articular epiphyseal cartilage in HLCFs. Methods 60 children who should be suspected to be HLCFs in clinical practice from Dec 2015 to Nov 2017 were continuously included as the first part patients. Subsequently, 35 HLCFs patients with complete follow-up information who had no obvious displacement on radiograph were the second part patients. The sensitivity and specificity of radiograph and MRI in diagnosing of HLCFs and their stability were calculated respectively. Calculated the sensitivity and specificity of each scan sequence of MRI in diagnosing of HLCFs osteochondral fractures. The degree of fracture displacement was measured respectively. Compared the ratio of surgical treatment, secondary fracture displacement and complications between the stable fracture group and the unstable fracture group on MRI in part 2 patients. Results Sensitivity of diagnosing HLCFs by MRI was significantly higher than radiograph (100.00% vs. 89.09%, P = 0.03). Sensitivity of diagnosing integrity of trochlear cartilage chain by MRI was 96.30%, which was significantly higher than that by radiograph (62.96%, P < 0.01). The sensitivity of cartilage sensitive sequence (3D-FS-FSPGR/3D-FSPGR) was different with FS-PDWI and FS-T2WI (P = 0.01 and P = 0.02, respectively). The degree of HLCFs displacement by MRI was higher than radiograph (P < 0.05). In the unstable fracture group, 5 cases (45.45%) had a fracture displacement of more than 2 mm on MRI, which was significantly higher than that in stable fracture group (0.00%, P < 0.01). Conclusions MRI is superior to the radiograph of elbow joint in evaluating and diagnosing children HLCFs and their stability. The coronal 3D-FS-FSPGR/3D-FSPGR sequence is a significant sequence for diagnosing osteochondral fractures in HLCFs. MRI can provide important clinical value for treatment decisions of HLCFs without significant displacement.