重症心脏瓣膜病瓣膜置换术后早期死亡率因素分析

目的探讨增加重症心脏瓣膜病瓣膜置换术后早期死亡率的因素，为降低早期死亡率和提高手术效果提供一定参考及借鉴。方法回顾性分析2004～2013年于本院行心脏瓣膜置换及成形术的171例患者的临床资料，分析术前、术中及术后各因素与术后早期死亡的关系，并采用χ^2检验分析及Logistic回归分析导致瓣膜置换术后早期死亡的相关因素。结果Logistic回归分析结果显示，瓣膜置换手术后早期死亡率的相关因素包括术前体重≥70kg、术前左心房内径≥70mm、术中主动脉阻断时间≥120min，OR值即Exp（B）分别为0．014、34．722、52-318．P〈0.05。结论左心房扩张明显、肥胖患者、术中主动脉阻断时间过长均增加瓣膜置换手术早期死亡率。

体外循环冠状动脉搭桥术围术期大量输注红细胞的危险因素分析

目的探讨体外循环冠状动脉旁路移植术(CCABG)围术期大量输注红细胞的危险因素。方法选取2013年2月-2017年10月在本院心脏外科接受单纯CCABG治疗的394名患者,按围术期红细胞输血量分为大量输血组(A1组,>4 U,n=223),少量或未输血组(A2组,≤4 U,n=171);记录2组患者的临床资料,包括年龄、性别、既往病史和术中相关数据,采用SPSS 21. 0应用单因素和Logistics回归分析CCABG围术期大量输注红细胞的危险因素。结果 CCABG输血比例为87. 82%(346/394),其中大量输血56. 60%(223/394),单因素分析显示A1组与A2组年龄、女性比例、BMI、吸烟史比例、术前静脉应用硝酸脂类药物、转机时间有明显差异(P<0. 05),多因素Logistic回归分析显示:BMI(χ^2=3. 864,OR 0. 933,P<0. 05)是CCABG围术期大量输注红细胞保护因素;女性(χ^2=6. 368,OR2. 163,P<0. 05)、转机时间长(χ^2=11. 087,OR 1. 008,P<0. 01)、术前静脉应用硝酸脂类药物(<24 h,χ^2=9. 419,OR1. 999,P<0. 01)是危险因素。结论女性、低BMI、术前静脉硝酸脂类药物(<24 h)、转机时间长是CCABG围术期大量输注红细胞的危险因素。

Changing the balance of the MTO reaction dual-cycle mechanism: Reactions over ZSM-5 with varying contact times

The methanol to olefins （MTO） reaction was performed over ZSM‐5 zeolite at 300℃ under various methanol weight hourly space velocity （WHSV） values. During these trials, the catalytic perfor‐mance was assessed, in addition to the formation and function of organic compounds retained in the zeolite. Analysis of reaction effluents and confined organics demonstrated a dual‐cycle reaction mechanism when employing ZSM‐5. The extent of the hydrogen transfer reaction, a secondary reac‐tion in the MTO process, varied as the catalyst‐methanol contact time was changed. In addition, 12C/13C‐methanol switch experiments indicated a relationship between the dual‐cycle mechanism and the extent of the hydrogen transfer reaction. Reactions employing a low methanol WHSV in conjunction with a long contact time favored the hydrogen transfer reaction to give alkene products and promoted the generation and accumulation of retained organic species, such as aromatics and methylcyclopentadienes, which enhance the aromatic cycle. When using higher WHSV values, the reduced contact times lessened the extent of the hydrogen transfer reaction and limited the genera‐tion of methylcyclopentadienes and aromatic species. This suppressed the aromatic cycle, such that the alkene cycle became the dominant route during the MTO reaction.

The Financing Situation and Suggestion of the Construction of Indemnificatory Housing in the Background of Land Finance Transformation

In recent years, the Chinese government has taken lots of measures to expand domestic demand and promote economic growth in response to the financial crisis. Accelerating the construction of indemnificatory housing is one of the most important measures. In order to solve the problem of the insufficient supply of the indemnificatory housing, the government speed up the construction of indemnificatory housing and constantly expand the scale of the construction. With the increase of indemnificatory housing, the problem of construction fund is increasingly highlighted. Large-scale construction of indemnificatory housing in the short term results in large funds pressure. Indemnificatory housing fund has several notable features, it requires a large demand for money and the capital turnover time is quite long. Also, its poor liquidity makes it difficult to get your money out at any time. In this article, the present situation and existing problems of indemnificatory housing are analyzed, the countermeasures and suggestions are put forward combining the capital sources of indemnificatory housing, so as to provide reference for indemnificatory housing financing.

Realization of Tip Tilting By 8-Step Line Tilting

By direct calculation of rotation matrices of SO(3),we show how certain specific sequence of eight consecutiverotations of digital angles can yield a tilting of a facet mirror.We also design a detailed program specifically to tiltan array of mirrors from planar orientation to the required focusing orientation.We describe how to use the 8-step torealize the focusing of the mirror array.We have found,in our designed program,an important feature of row-sharingduring the rotations for the columns and similarly the column-sharing during the rotations for the row.This feature cansave a lot of operating time during the actual realization of the mechanical movements.

Continuous on-line adaptation of the rotor time constant in FOC induction machine system

Rotor time constant is an important parameter for the indirect lleld oraentateO control of mauc- tion motor. Incorrect rotor tittle constant value will cause the flux observer generating a wrong angu- lar orientation of the rotor field. A new approach serves for rotor time constant on-line adaptation by setting the stator current to be zero for a short period. A smooth eorrector is designed to prevent ab- normal detection result from making adaptation. Impact of zero current duration on detection error and rotor speed is analyzed by experiments.

Time-stepping finite element analysis on the influence of skewed rotors and different skew angles on the losses of squirrel cage asynchronous motors

To study the influence of skewed rotors and different skew angles on the losses of squirrel cage asynchronous motors,a 5.5-kW motor was taken as an example and the multi-sliced field-circuit coupled time stepping finite element method(T-S FEM)was used to analyze the axially non-uniform fundamental and harmonic field distribution characteristics at typical locations in the stator and rotor cores.The major conclusions are:firstly the skewed rotor exhibits a decrease in the harmonic copper losses caused by slot harmonic currents in the stator winding and rotor bars.Secondly,the skewed rotor shifts the non-uniform distribution of field in the axial direction,which leads to more severe saturation and an increase in iron losses.The heavier the load,the more pronounced the increase in iron losses.Furthermore,the influences of different skew angles on motor losses are studied systematically,with skew angles from 0.5 to 1.5 stator tooth pitch.It is found that the lowest total loss occurs at 0.8 stator tooth pitch,and the slot harmonics can be decreased effectively.

A new cellular automaton model for traffic flow considering realistic turn signal effect

In real traffic,any vehicle must give lane-changing signal(i.e.the turn signal) before changing lanes;at this time,the vehicles behind the lane-changing vehicle will be hindered and may form "plugs" due to the turn signal effect.However,few studies focus on exploring the effect.In this paper,the turn signal effect was taken into account by proposing a new symmetric two-lane cellular automaton(T-STCA) model,and the new model was set to compare with the STCA,H-STCA and A-STCA models.Numerical results show that using the T-STCA model to describe lane-changing or overtaking,the process appeared in several consecutive time steps;while using the other three models,the process appeared only in one time step.In addition,the T-STCA model could describe the mixed traffic flow more realistically and the turn signal effect could help the plugs to dissolve more quickly.