A case of unusual acquired factor V deficiency

Dear editor,Factor V deficiency is a rare bleeding disorder,which includes congenital and acquired factor V deficiencies.Congenital factor V deficiency(CFVD)is an autosomal recessive disorder with an estimated prevalence of 1:1,000,000.[1]However,acquired factor V deficiency(AFVD)is even rarer.

Discussion on the sweep efficiency of hybrid steam-chemical process in heavy oil reservoirs: An experimental study

Non-condensable gas(NCG),foam and surfactant are the three commonly-used additives in hybrid steam-chemical processes for heavy oil reservoirs.Their application can effectively control the steam injection profile and increase the sweep efficiency.In this paper,the methods of microscale visualized experiment and macroscale 3D experiment are applied to systematically evaluate the areal and vertical sweep efficiencies of different hybrid steam-chemical processes.First,a series of static tests are performed to evaluate the effect of different additives on heavy oil properties.Then,by a series of tests on the microscale visualized model,the areal sweep efficiencies of a baseline steam flooding process and different follow-up hybrid EOR processes are obtained from the collected 2D images.Specifically,they include the hybrid steam-N_(2)process,hybrid steam-N2/foam process,hybrid steam-surfactant process and hybrid steam-N2/foam/surfactant process(N2/foam slug first and steam-surfactant co-injection then).From the results of static tests and visualized micromodels,the pore scale EOR mechanisms and the difference between them can be discussed.For the vertical sweep efficiencies,a macroscale 3D experiment of steam flooding process and a follow-up hybrid EOR process is conducted.Thereafter,combing the macroscale 3D experiment and laboratory-scaled numerical simulation,the vertical and overall sweep efficiencies of different hybrid steam-chemical processes are evaluated.Results indicate that compared with a steam flooding process,the areal sweep efficiency of a hybrid steam-N2process is lower.It is caused by the high mobility ratio in a steam-N2-heavy oil system.By contrast,the enhancement of sweep efficiency by a hybrid steam-N2/foam/surfactant process is the highest.It is because of the high resistance capacity of NCG foam system and the performance of surfactant.Specifically,a surfactant can interact with the oil film in chief zone and reduce the interfacial energy,and thus the oil droplets/films formed during steam injection stage are unlocked.For NCG foam,it can plug the chief steam flow zone and thus the subsequent injected steam is re-directed.Simultaneously,from the collected 2D images,it is also observed that the reservoir microscopic heterogeneity can have an important effect on their sweep efficiencies.From the 3D experiment and laboratory-scaled numerical simulation,it is found that a N2/foam slug can increase the thermal front angle by about 150 and increase the vertical sweep efficiency by about 26%.Among the four processes,a multiple hybrid EOR process(steam-N2/foam/surfactant process) is recommended than the other ones.This paper provides a novel method to systematically evaluate the sweep efficiency of hybrid steam-chemical process and some new insights on the mechanisms of sweep efficiency enhancement are also addressed.It can benefit the expansion of hybrid steam-chemical processes in the post steamed heavy oil reservoirs.

Infective bicuspid aortic valve endocarditis causing acute severe regurgitation and heart failure:A case report

BACKGROUND Infective endocarditis(IE)is an uncommon but potentially life-threatening infection,which occasionally develops into acute severe valve insufficiency leading to the onset of heart failure,and necessitates timely intervention.However,the variable and atypical clinical manifestations always make the early detection of IE difficult and challenging.CASE SUMMARY A 45-year-old female who was previously healthy presented with exertional shortness of breath and paroxysmal nocturnal dyspnea.She also suffered from a significant decrease in exercise capacity,whereas her body temperature was normal.She had severe hypoxemia and hypotension along with a marked aortic valve murmur.Diffuse pulmonary edema and bilateral pleural effusion were observed on both chest X-ray and computed tomography scan.Transthoracic echocardiography was performed immediately and revealed severe regurgitation of the bicuspid aortic valve.Transesophageal echocardiography was further performed and vegetations were detected.In addition to adequate medical therapy and ventilation support,the patient underwent urgent and successful aortic valve replacement.Her symptoms were significantly relieved and the postoperative chest X-ray showed that pulmonary edema was significantly reduced.Histopathology of the resected valve and positive microorganism culture of the surgical specimen provided evidence of definite IE.CONCLUSION IE should be considered in critical patients with refractory heart failure caused by severe bicuspid aortic valve regurgitation.