气体体积流量测量中温度和压力修正的必要性

气体流量测量中,温度和压力修正是提高气体流量测量精度的重要手段之一.文中分别介绍温度和压力偏离设定值时对使用直接输出流量计和差压式流量计进行流量测量所带来的误差,并通过工程实例示出温度和压力在8种极端变化状况下产生的测量误差,以对温度和压力变化造成的误差提供一些量的概念.指出,如今实施温度和压力修正并不像以前单元组合仪表那样麻烦,应适当考虑修正.最后给出几点推荐性意见.     

流量测量不准确的原因分析

根据钢铁厂中流量计使用的现况,在流鞋计选型是否恰当、工艺参数是否正确、设计是否考虑了足够的直管段长度和温/压修正手段、以及安装是否正确等方面对流最测量不准确的原因作粗浅的分析,并提出改进建议.随着新型流量计的不断推出,其性能和适用范围可能有更多的优越性,但在使用中总有一定的局限性,因此提供正确的工艺参数水远是必要的,使用中要充分注意.     

封闭管道流量的非接触式测量

在流体传动系统中，流量是需经常测量的过程参数之一。本文先指出了非接触法测流量的优越性，再基于各种物理原理，叙述了封闭管道流量的几种非接触测量方法与特点。     

Comparative analysis of different permeabilization methods for the flow cytometry measurement of cytoplasmic myeloperoxidase and lysozyme in normal and leukemic cells

Using a direct one-color (fluorescein isothiocyanate; FITC) staining method with a Facscan flow cytometer, we evaluated the intracellular expression of two granular constituents of myeloid cells [myeloperoxidase (MPO) and lysozyme] on leukemic cells from 21 patients with acute myeloid leukemia (AML), and 6 patients with acute lymphoblastic leukemia (ALL). Three different permeabilization techniques were used [FACS Lysing Solution (FLy), B.Dis; Ortho-PermeaFix (OPF); Fix and Perm (F&P), Caltag] prior to monoclonal antibody (McAb) staining, in order to verify the specificity and the sensitivity of the three labelling methods towards the two model antigens. Peripheral blood cells from 15 healthy subjects and Ortho Absolute Control served as controls. Data were expressed as percentage of positivity, net fluorescence intensity, ratio between mean fluorescence intensity (MFI) of positive cells and that of isotypic controls (P/N ratio; evaluated in both geometric and arithmetic scale), and, in 12 representatives cases (7 AML, 5 normal samples), in the form of both molecules of equivalent soluble fluorochromes (MESF) and antibody binding capacities (ABC). As far as the antigenic expression of MPO and lysozyme in normal samples is concerned, F&P resulted, in our hands, in the most specific and sensitive staining, followed by FLy solution and OPF, which showed positivity for MPO, and, to lesser extent, for lysozyme in a considerable manner of lymphocytes (means 64% and 54%, respectively, for OPF and FLy; range of ABC/cell: 0.9-5.2 x 10(3)) obtained from healthy subjects. With the reference F&P permeabilizing solution, 90% and 80% of FAB M1-M5 cases were found to be positive for MPO and lysozyme, respectively. However, M1, M2, and M3 AML FAB (French-American-British) subvarieties were characterized by a brighter expression for MPO (mean ABC/cell: 89 x 10(3)) than that of lysozyme (mean ABC/cell: 12.5 x 10(3D)), whereas blast cells from patients with M5a FAB subtypes showed higher levels of lysozyme (mean ABC/cell: 65 x 10(3)) than that of MPO (mean ABC/cell: 0.1 x 10(3)). One of five cases of FAB MO AML showed a dull positivity for MPO-7 McAb. Patients with ALL were MPO and lysozyme negative using both F&P and FLy reagents, although a certain degree of positivity was documented in some cases with OPF. Taking these data together, it can be stated that the use of anti-MPO McAbs may be of great value for the diagnosis and monitoring of acute leukemia and, along with lysozyme McAb, can provide useful information in the distinction of myeloid from monocytic leukemias and in the lineage assignment of apparently biphenotypic forms. However, the methodology used for the detection of these myeloid-associated antigens is critical for a correct interpretation of cytofluorimetric data and should be taken into account when evaluating data coming from multicenter trials dealing with leukemias. A standardization of cytofluorimetric analysis of intracellular antigens is needed in order to improve the reproducibility and comparability of results in multicenter studies.     

Comparative effects of volume loading on pulmonary venous flow in dogs with normal heart and with myocardial ischemia

1. Stroke-prone spontaneously hypertensive rats (SHRsp) have been used widely to test agents putatively capable of vascular protection. These animals present an accelerated time course of hypertension and a reduced life-span. When fed a high-sodium diet from the eighth week of life, a further acceleration in blood pressure increase is obtained, and rats start to die after 5 weeks of diet as a consequence of cerebral haemorrhage. In this model, angiotensin-converting enzyme (ACE) inhibitors were repeatedly proved to prevent vascular lesions and death. Notably, this effect was independent of any hypotensive effect. On the contrary, diuretics were shown not to be equally effective. A combination of ACE inhibitors and diuretics, although known to have synergistic effects in the therapy of hypertension, has never previously been tested. 2. Our aim was to study the effects of long-term treatment with the ACE inhibitor delapril (12 mg day-1 kg-1), the thiazide-like diuretic indapamide (1 mg day-1 kg-1), and their combination (12 and 1 mg day-1 kg-1 respectively), on the survival of SHRsp rats fed a high-sodium diet from the eighth week of life onwards. The effects of the treatments on blood pressure, body weight, food and fluid intake, diuresis, proteinuria and the appearance of lesion signs and death were assessed weekly. When control rats reached 50% mortality, they were killed, together with some drug-treated rats, to compare lesions in brain and kidney. The other drug-treated rats continued treatments until 50% mortality was reached in two treatment groups. 3. All drug treatments were able to delay death significantly when compared with control rats, which reached 50% mortality after 6 weeks of salt loading. This event was preceded by a highly significant increase in proteinuria, diuresis and fluid intake that took place 3 weeks after the increase in blood pressure over the initial range. In delapril- or indapamide-treated SHRsp these changes were never seen, even when animals started to die. In the combination-treated group, a significant increase (P < 0.01) in fluid intake and diuresis, but not proteinuria, was observed from the third week of treatment onwards. 4. Treatment with delapril or indapamide did not block the progressive increase in blood pressure as observed in control animals. However, the increase in blood pressure was markedly retarded with respect to control rats. At variance with this, in combination-treated animals blood pressure levels were maintained until the end of the experiment within the 99% confidence interval initially observed in control animals. 5. Infarctual and haemorrhagic cerebral lesions were observed in 38% of control rats; no lesions were noted in brains of age-matched rats receiving a drug treatment. Kidneys from control animals presented major degenerative lesions of glomeruli and arteries, characterized by fibrinoid necrosis. This condition was absent in drug-treated animals, which presented minor signs of ischaemic lesion. Heart hypertrophy, when heart weight was expressed as a percentage of body weight, was similar in saline-, delapril- or indapamide-treated rats. At variance with this, in combination-treated animals the heart weight to body weight ratio was significantly (P < 0.01) lower than in the other groups. 6. In conclusion, the diuretic indapamide showed similar protective effects as the ACE inhibitor delapril on acute vascular lesions and survival of SHRsp. Moreover, their combination synergized in preventing heart hypertrophy consequent to longterm hypertension. This results is probably related to the enhanced diuresis and the better control of blood pressure levels selectively found in combination-treated animals.     

A measurement of liver volume and its changes in post-hepatitic cirrhosis

By use of the computerized digital image processing system, the liver volume in vivo was successfully measured and the three dimensional image of the liver rebuilt in 62 cases of posthepatitic cirrhosis and 15 noncirrhotics. It was found (1) The liver volume of 474.64 +/- 115.28cm3/m2 in Chinese cirrhotics is significantly smaller than that of the control (P < 0.001); (2) In most cases, patients in class I of the liver function have a larger liver volume; (3) Patients with smaller liver volume have poor tolerance to surgery with a critical value of 400cm3/m2; (4) the liver volume considerably reduced after shunt plus devascularization but did not change after devascularization only.     

Clinical death and the measurement of stressed vascular volume

OBJECTIVES: To measure stressed vascular volume in humans and to review the concepts of stressed and unstressed vascular volume. DESIGN: Observational study during surgical procedure. SETTING: Operating room at a university hospital. PATIENTS: Five patients undergoing hypothermic circulatory arrest for surgery on major vessels. INTERVENTION: We measured the volume that drained from the patient to the reservoir of the pump when the pump was turned off. MEASUREMENTS AND MAIN RESULTS: Stressed volume was 20.2+/-1.0 mL/kg, which is 30% of the predicted blood volume of these patients. CONCLUSION: The amount of blood volume that determines vascular filling pressure is only about a quarter of the total predicted volume, which means that there is a large reserve of unstressed volume that can be recruited to maintain vascular filling pressure.     

The airway resistance-lung volume plot as a measurement of the closing volume

Following abdominal surgery, insulin and glucose concentrations in the portal vein, and a peripheral vein are compared in patients during control periods and after oral administration of glucose. During the control period, the glucose concentrations are identical in both veins. After glucose loads with the prompt increase of portal glucose concentration the portal-peripheral difference also increases (p less than 0.01). During the control period the insulin concentration in the portal vein is double as compared to peripheral blood (p less than 0.005). After glucose load the increasing portal insulin as well as the peripheral and portal glucose correlate with the portal-peripheral insulin difference (p less than 0.001). Furthermore, there is a significant positive correlation between the peripheral glucose area as a parameter of glucose tolerance and the portal insulin area as a semiquantitative parameter of insulin secretory capacity (p less than 0.001). It can be concluded that in the early postoperative period in patients with a diminished oral glucose tolerance (large glucose areas) there is an even greater insulin response in comparison to patients with normal oral glucose tolerance. On the other hand, however, in those patients with diminished glucose tolerance, the insulin response is essentially delayed.     

球团烟气密相干塔脱硫-除尘一体化系统优化

 为探明脱硫-除尘一体化系统内反应密集区以及因袋式除尘器远端利用率不高而导致除尘效率低下的原因,急需对一体化系统内流场分布进行研究。应用Fluent软件对密相干塔脱硫-除尘一体化系统进行仿真模拟,标准[κ-ε]湍流模型模拟气相流动,离散相（DPM）模型模拟固相流动,对改进前后的一体化系统进行模拟。模拟结果表明：除尘器内部增加气流板及改变风口布置方式对烟气在除尘器内的均匀流动都起到了良好的作用,其中改变风口布置方式效果更显著。密相干塔内部导流板最优设计长度为7.5 m,角度为45 °。     

密相干塔烧结烟气脱硫系统仿真研究

应用Fluent软件对密相干塔模拟仿真,研究了烟气整流系统和链式搅拌器对烟气流场和湍流、循环灰轨迹及系统压力损失的影响,并在模拟工况下确定了烟气整流系统较优导流板布置形式.研究结果表明,链式搅拌器能够显著增大塔内附近区域的湍动能,提高转速不能明显提高整体烟气湍流强度,双层链式搅拌器可以增大高湍流强度区且减缓其衰减速度,该工况下安装双层链式搅拌器,转速为100 r·min^-1较为理想,此时密相干塔能够实现烟气均布和气固充分接触,大部分颗粒参与内循环,少部分进入除尘器,系统压损约为200 Pa.     

Quantitative single-photon emission tomography for tumour blood flow measurement in bronchial carcinoma

A single-photon emission tomography (SPET) technique for the absolute measurement of tumour perfusion is described. Phantom studies have shown that source-background ratios are dependent upon source size and radial position within the phantom. A means of correcting source-background count ratios for these variables has been developed and used to correct tumour-lung ratios obtained in 28 patients with bronchial carcinomas who underwent technetium-99m hexamethylpropyleneamine oxime (99mTc-HMPAO) SPET. On SPET images, the normal lung appears as a relatively homogeneous background. The relationship between 99mTc background concentration (kBq/ml) and counts/pixel was determined from phantom studies and the tumour 99mTc concentration from the background 99mTc concentration and corrected tumour-lung ratio. The total activity of the lipophilic 99mTc-HMPAO species injected was measured. The activity reaching the systemic circulation (Asys) was obtained by subtracting the activity trapped in the pulmonary circulation (obtained from background 99mTc concentration and lung volume). Tumour blood flow may then be calculated from fraction of Asys contained in the tumour provided cardiac output and extraction fraction are known. Blood flow through the central region of tumours ranged from zero to 59.0 (mean 14.1) ml min-1 100 g-1 and through the whole tumour from 0.6 to 68.0 (mean 20.6) ml min-1 100 g-1.     

平展流冷态湍流场的PIV测量

针对单烧嘴湍流预混平焰冷态实验模型,采用粒子激光测速(PIV)技术对烧嘴下方主要燃烧区的速度场(250mm×350mm)进行了测量,得出在旋流强度为1.76,空气量/煤气量为19.39下的速度场。速度场由回流区、附壁射流区和过渡区组成,同时进一步分析了三个区域内径向速度和轴向速度的变化规律。     

Colour Doppler flow in normal axillary lymph nodes

81 women with carcinoma of the breast who underwent axillary nodal dissection were studied pre-operatively with colour Doppler ultrasound. The presence of colour Doppler flow was demonstrated in 83.6% of normal lymph nodes compared with 87.5% of metastatic lymph nodes. Using the presence of colour Doppler signal as the sole diagnostic criterion for the diagnosis of metastasis gave a sensitivity of 92.5%, specificity of 9.52%, accuracy of 50%, positive predictive value of 49.3% and negative predictive value of 57.1%. Using grey scale sonographic criteria, where a metastatic node was defined as a node with loss of central fatty hilum and/or eccentric cortical hypertrophy, a sensitivity of 79.5%, specificity of 94.0%, accuracy of 87.6%, positive predictive value of 91.2% and negative predictive value of 85.5% were obtained. Colour Doppler studies of the axillary nodes in a second group of 106 women who attended for breast cancer screening and had no significant breast or axillary pathology also showed colour Doppler signal in 86.7% of nodes. It is concluded that colour Doppler flow signals can be demonstrated in both normal and metastatic axillary lymph nodes, and is highly non-specific when used as the sole diagnostic criterion in the diagnosis of malignancy.     

A novel method for measurement of cerebral blood flow in the animal experiment

A method is described for the measurement of cerebral blood flow by coutinuous registration of the venous out-flow from the temporal sinus of anaesthetized dogs. This method can be used advantageously for the screening of unknown compounds because samples of "cerebral" venous blood are obtained by a less complicated and reliable technique. Changes in cerebral blood flow induced with well defined substances, were registered with our method. The results are discussed.     

转炉氧气流量测量中温度压力补偿的实现

分析了转炉氧气流量测量中，温度压力变化对测量结果的影响。参考智能仪表的设计思路，提出了应用PLC控制系统中的软件方法，实现对氧气流量的温度压力补偿，从而提高了计量的准确性。     

Effects of physical parameters on the cylindrical model for volume measurement by conductance

A simple fiber length-reduction method was developed to obtain a large amount of fiber samples with different length distributions for use in various biological experiments. This press method is only to press a raw fiber sample charged in a stainless cylinder at an adequate pressure, and is effective for man-made mineral fibers (MMMF) such as glass wool, rock wool and wool and refractory fibers (ceramic fibers, mullite fibers) and some brittle natural mineral fibers such as fibrous brucite and wollastonite. The mean fiber-length of man-made mineral fibers became shorter with the increase in the pressure applied without diameter change. We could obtain a length-reduced fiber sample with a suitable length distribution by this method. This press method is therefore a size-selective method able to produce a large amount of pulverized fiber sample depending on the press cylinder size for biological experiments. A very small amount of non-fibrous particles with aspect ratios (length vs. diameter) of under 3 was seen in the pulverized fiber samples. To eliminate such non-fibrous particles as well as too long fibers from the sample, separation by sedimentation in water was somewhat effective.