依维莫司单独与联合唑类药物对耐药念珠菌体外敏感研究

目的探讨依维莫司单独及联合伊曲康唑、伏立康唑、泊沙康唑和氟康唑对耐药念珠菌及耳念珠菌的体外作用。方法于2022年3—6月,采用美国临床实验室标准研究所M27-A3微量稀释法和微量肉汤稀释棋盘技术研究依维莫司联合伊曲康唑、伏立康唑、泊沙康唑及氟康唑对耐药念珠菌及耳念珠菌的体外治疗作用。通过测定最低抑菌浓度(MIC)和部分抑菌浓度指数来确定协同效应。结果依维莫司单药治疗22株耐药念珠菌及10株耳念珠菌的MIC为0.250~4.000 mg/L、1.000 mg/L,伊曲康唑、伏立康唑、泊沙康唑、氟康唑单独使用对22株耐药念珠菌MIC范围分别为0.125~4.000 mg/L、<0.125~2.000 mg/L、0.063~2.000 mg/L、1.000~64.000 mg/L,伊曲康唑、伏立康唑、泊沙康唑单独使用对10株耳念珠菌MIC范围分别为0.500~2.000 mg/L、0.125~8.000 mg/L、0.125~1.000 mg/L。当依维莫司与伊曲康唑、伏立康唑、泊沙康唑、氟康唑联合使用时,对耐药念珠菌的协同作用分别是9株(40.90%)、4株(18.18%)、8株(36.36%)、9株(40.90%)。当依维莫司联合唑类作用于耳念珠菌,未发现任何拮抗作用。结论依维莫司单独使用对耐药念珠菌及耳念珠菌菌株具有明显抗真菌作用,同时依维莫司联合唑类作用于耐药念珠菌时,表现出良好的协同作用,且没有拮抗作用,其进一步提升其抗耐药念珠及耳念珠菌的作用。

黄曲霉果胶酶的酶学特性及其在白玉兰落叶水解中的应用

农业残余物还田能够改善土壤质量,然而微生物活性过低使腐熟进程缓慢。为了加快腐熟进程,本研究从土壤中筛选产果胶酶的菌株,并进行菌株鉴定及酶学性质分析,同时研究所产果胶酶对白玉兰(Magnolia denudata)落叶的水解作用。结果显示,从土壤中分离得到菌株TPF2-1,被鉴定为黄曲霉(Aspergillus flavus),其所产果胶酶粗酶的酶活力为(0.63±0.02)IU/mL。以聚半乳糖醛酸为底物时,TPF2-1果胶酶粗酶的最适作用pH值为4.5,最适作用温度为50℃;在35℃保温1 h后酶活力无损失;在pH值4.0-7.0、25℃条件下保温24 h后仍残余大于90%的酶活力;1、2和5 mmol/L的Li^(+)、Na^(+)、Mg^(2+)、K^(+)、Cu^(2+)、Zn^(2+)和Co^(2+)对TPF2-1果胶酶粗酶的酶活力均无明显抑制作用,Ca^(2+)、Fe^(2+)和Fe^(3+)在5 mmol/L时表现出抑制作用。TPF2-1果胶酶粗酶可使白玉兰落叶水解体系中还原性物质的量提升至水解前的3.3倍。本研究结果表明黄曲霉果胶酶在树叶还田方面具有潜在的应用价值。

空气涡轮火箭发动机起动过程推进剂供应及尾喷管面积变化规律研究

为了认识固体推进剂空气涡轮火箭发动机推进剂供应快慢和尾喷管面积变化对发动机起动过程产生的影响,采用容积法建立了考虑工质变比热及化学平衡的发动机动态模型,通过给定不同的推进剂供应速率、尾喷管喉部面积大小及尾喷管喉部面积随转速变化速率,模拟了发动机各工况下的起动过程,对比分析了这些参数对发动机起动时间、共同工作线位置的影响规律。研究发现,增加推进剂供应速率会使发动机起动时间降低,但压气机更接近喘振边界,当尾喷管喉部面积较小时,尾喷管会出现壅塞现象,导致压气机喘振。在此基础上,给出了采用较快推进剂供应速率和尾喷管喉部面积随转速升高而增大相结合的调节方法,使压气机在避免喘振的同时远离堵塞边界,实现了发动机的快速安全起动。

Effect of Geometric Variation of Root Fillet on the Flow Characteristic of a Transonic Compressor Rotor

The effects of root fillet on the flow behavior of high loading compressor rotor tends to be much more crucial in practice,and it’s necessary to explore the internal relations between the geometric effects of root fillet and the flow behaviors of rotor blade.Therefore,eight types of root fillet with different radius were designed and installed around the blade root of NASA Rotor67.With the aids of fillet,the corner separation near suction side of blade root has been suppressed significantly in that the root fillet reconstructs the circumferential bending distributon of the suction-side curve from leading edge to trailing edge,and reduces the genmetric turning angle in the latter part of root section near trailing edge.However,apart from the improvement of corner flow characteristic caused by root fillet,both the tip flow deterioration and the decrease of stall margin occur in the new rotors,which indicates an indirect correlation between tip flow characteristic and root fillet exists indeed in the three-dimensional flowfields of transonic rotor.Actually,by means of the new radial pressure equilibrium affected by root fillet,a larger radius of root fillet contributes to much larger blade loading and stronger leakage flow in tip region of compressor rotor.As a result,a monotonic decrease of stall margin was present in the transonic rotor with increase of the root fillet radius.Subsequently,the positive bending of blade tip was introduced to deal with the negative effect caused by the root fillet indirectly.Combined with the effects of root fillet and positive tip-bending on the radial pressure equilibrium existing in channels,both the radial and streamwise loading distributions tend to be much more reasonable in new rotors,and the static pressure difference in former 1/3 chord of blade tip has decreased clearly which benefits to reduce the strength of leakage flow in tip region.Therefore,the flow deterioration in tip region of transonic rotor induced by root fillet has been well suppressed,with an obvious improvement of overall performance occurring in new rotors.