Effects of the precipitation of stabilizers on the mechanism of grain fracturing in a zirconia metering nozzle

The mechanism of grain fracturing in a zirconia metering nozzle used in the continuous casting process was studied. The phase composition, microstructure, and chemical composition of the residual samples were studied using an X-ray fluorescence analyzer, scanning electron microscope, and electron probe. Results revealed that the composition, structure, and mineral phase of the original layer, transition layer, and affected layer of the metering nozzle differed because of stabilizer precipitation and steel slag permeation. The stabilizer MgO formed low-melting phases with steel slag and impure SiO2 on the boundaries（pores） of zirconia grains; consequently, grain fracturing occurred and accelerated damage to the metering nozzle was observed.

Role of the posterior deep deltoid ligament in ankle fracture stability: A biomechanical cadaver study

BACKGROUND The deltoid ligament is a key component of ankle fracture stability.Clinical tests to assess deltoid ligament injury have low specificity.In supination externalrotation(SER)type-IV ankle fractures,there is either a medial malleolus fracture or deltoid ligament injury.These injuries are often considered unstable,requiring surgical stabilisation.We look to identify the anatomical basis for this instability.This study investigates the anatomical basis for such instability by re-creating SER type ankle fractures in a standardised cadaveric study model,investigating the anatomical basis for such instability.AIM To investigate the anatomical basis for fracture instability in SER type ankle fractures.METHODS Four matched pairs of cadaveric limbs were tested for stability both when axially loaded and under external rotation stress.Four matched pairs of cadaveric limbs(8 specimens)were tested for stability when axially loaded to 750 N with a custom rig.Specimens were tested through increasing stages of SER injury in a stepwise fashion before restoring the lateral side with open reduction and internal fixation(ORIF).Clinical photographs and radiographs were recorded at each step.We defined instability in accordance with well accepted radiological parameters:>4 mm medial clear space opening on a mortise-view radiograph or>7 degrees of talar tilt.RESULTS All specimens with an intact posterior deep deltoid ligament were stable.Once the posterior deep deltoid ligament was sectioned there was instability in all specimens.Stabilisation of the lateral side prevented talar shift,but not talar tilt.CONCLUSION If the posterior deep deltoid ligament is intact then SER fractures can be managed without surgery.If the posterior deep deltoid is incompetent,ORIF and cautious rehabilitation is recommended because the talus can still tilt in the mortise.

Effect of hydraulic fracturing induced stress field on weak surface activation during unconventional reservoir development

Unconventional reservoirs usually contain many weak surfaces such as faults,laminae and natural fractures,and effective activation and utilization of these weak surfaces in reservoirs can significantly improve the extraction effect.In hydraulic fracturing,when the artificial fracture approaches the natural fracture,the natural fracture would be influenced by both the original in-situ stress field and the hydraulic fracturing-induced stress field.In this paper,the hydraulic fracturing-induced stress field is calculated based on the relative position of hydraulic fracture and natural fracture,the original in-situ stress,the net pressure inside the hydraulic fracture and the pore pressure of the formation.Furthermore,the stability model of the natural fracture is established by combining the Mohr-Coulomb rupture criterion,and extensive parametric studies are conducted to explore the impact of each parameter on the stability of the natural fracture.The validity of the proposed model is verified by comparing with the reservoir characteristics and fracturing process of the X-well 150e155 formation in the Songliao Basin.It is found that the stress field induced by the hydraulic fracture inhibits the activation of the natural fracture after the artificial fracture crossed the natural fracture.Therefore,for similar reservoirs as X-well 150e155,it is suggested to connect natural fractures with hydraulic fractures first and then activate natural fractures which can effectively utilize the natural fractures and form a complex fracture network.

Undetected traumatic cardiac herniation like playing hide-and-seek-delayed incidental findings during surgical stabilization of flail chest:A case report

BACKGROUND Post-traumatic blunt pericardial injury is a rare condition with only a few reported cases which were generally diagnosed during initial examinations upon admission.However,pericardial injuries not bad enough to dislocate the heart may only cause intermittent electrocardiogram(ECG)changes or be asymptomatic.CASE SUMMARY In this case,we report a blunt pericardial injury undetected on preoperative transthoracic echocardiography and chest computed tomography.We misjudged intermittent ECG changes and blood pressure fluctuations as minor symptoms resulting from cardiac contusion and did not provide intensive treatment.The pericardial injury was found incidentally during surgical stabilization of rib fractures and was successfully repaired.CONCLUSION Post-traumatic blunt pericardial ruptures should be considered in patients with blunt chest trauma showing abnormal vital signs and ECG changes.

Advances and disputes of posterior malleolus fracture

Objective The objective of this article is to summarize the development of evaluation and treatment of posterior malleolus fracture （PMF）. Data sources Data used in this Study selection Articles were review were mainly from English literature of PubMed data base. ncluded in this review if they were related to the PMF or trimalleolar fracture.

The Chinese consensus for surgical treatment of traumatic rib fractures 2021(C-STTRF 2021)

Rib fracture is the most common injury in chest trauma.Most of patients with rib fractures were treated conservatively,but up to 50%of patients,especially those with combined injury such as flail chest,presented chronic pain or chest wall deformities,and more than 30%had long-term disabilities,unable to retain a full-time job.In the past two decades,surgery for rib fractures has achieving good outcomes.However,in clinic,there are still some problems including inconsistency in surgical indications and quality control in medical services.Before the year of 2018,there were 3 guidelines on the management of regional traumatic rib fractures were published at home and abroad,focusing on the guidance of the overall treatment decisions and plans;another clinical guideline about the surgical treatment of rib fractures lacks recent related progress in surgical treatment of rib fractures.The Chinese Society of Traumatology,Chinese Medical Association,and the Chinese College of Trauma Surgeons,Chinese Medical Doctor Association organized experts from cardiothoracic surgery,trauma surgery,acute care surgery,orthopedics and other disciplines to participate together,following the principle of evidence-based medicine and in line with the scientific nature and practicality,formulated the Chinese consensus for surgical treatment of traumatic rib fractures(STTRF 2021).This expert consensus put forward some clear,applicable,and graded recommendations from seven aspects:preoperative imaging evaluation,surgical indications,timing of surgery,surgical methods,rib fracture sites for surgical fixation,internal fixation method and material selection,treatment of combined injuries in rib fractures,in order to provide guidance and reference for surgical treatment of traumatic rib fractures.

Stabilization of unstable pelvic fractures with a novel internal-external fixator

An internal-external fixator for stabilization in three cases with unstable pelvic fractures were reported. Compared with external fixation, the internal-external fixator, which is placed in the subcutaneous layer, decreased the risk of pin-track infection, pin site pain, and bowel obstruction; meanwhile, it had the advantage of external fixation： it was easy to apply, controlled damage, and resulted in minimal injury.

Effects of Ni on austenite stability and fracture toughness in high Co-Ni secondary hardening steel

Three kinds of high Co Ni secondary hardening steels with different Ni contents were studied. The nanoscale austenite layers formed at the interface of matensite laths were observed. Both observation and diffusion kinetic simulation results showed that both Ni and Co did not obtain enough time to get the equilibrium content in this system. The Ni content in austenite layers decreased significantly, and Co content increased slightly with the decrease of Ni content in overall composition. The austenite stability was estimated by Olson-Cohen model, in which both chemical and mechanical driving force could be calculated by equilibrium thermodynamic and Mohr＇s circle methods, respectively. Simulation and mechanical test results showed that The decrease of Ni content in austenite layers would cause the change of austenite stability and decrease the fracture toughness of the steels. When the Ni content in the overall composition was lower than 7 wt. %, the Ni content in y phase would be lower than 20 wt.%. And the simulation value of M; （stress induced critical martensite transformation temperature） would be up to 80 ℃, which was about 60℃ higher than room temperature. Based on the analysis, the Ni content in the overall composition of high Co Ni secondary hardening steels should be higher than 8 wt. % in order to obtain a good fracture toughness.