电脑控制连续式料位仪的研制

论述了电脑控制连续式料位仪的原理及性能，研制了一种先进可靠的物料料位测量工具。     

Suicide substrate reaction-diffusion equations: Varying the source

The suicide substrate reaction is a model for certain enzyme-inhibitingdrugs. This reaction system is examined assuming that the substratediffuses freely while the enzyme remains fixed. Two sets ofinitial and boundary conditions are examined: one modellingan instantaneous point source, akin to an injection of substrate,the other, a continuous point source, akin to a continuing influx,or intravenous drip, of substrate. The quasi-steady-state assumptionis applied to obtain analytical solutions for a limited parameterspace. Finally, further applications of numerical and analyticalexperimentation on pharmaceutical mechanisms are described.     

The evidence for physiologic management of the active phase of the first stage of labor

The active phase of first stage labor is generally defined as the period between 3 cm to 4 cm to complete cervical dilatation, in the presence of regular uterine contractions. Most women will experience this portion of labor within hospital obstetric units, where care commonly features restriction to bed, electronic fetal monitoring, early treatment of "slow" labors, and few pain management options beyond epidurals and narcotics. However, the available evidence on appropriate care for healthy childbearing women favors activity in labor, intermittent auscultation, patience from caregivers, and nonpharmacologic methods of pain relief. This article reviews the evidence for care practices that support physiologic labor. Modifying intrapartum care to reflect current evidence will improve women's health, and will require a multilevel approach and consistent midwifery demonstration of the model.     

Low-density lipoprotein subfraction profiles in dialysis patients

Summary: Uraemic dyslipidaemia is a major risk factor for cardiovascular disease in end-stage renal failure patients. In patients without renal failure, high levels and qualitative abnormalities of low-density lipoprotein (LDL) are known to be atherogenic. Recently, LDL subfraction analysis has associated premature coronary artery disease with a high prevalence of small, dense LDL particles characterizing the LDL subclass phenotype B. We therefore examined the lipid profiles, LDL subfraction distribution and phenotypes in our population of haemodialysis (HD; n = 30) and peritoneal dialysis patients (PD; n = 17), and compared them to 40 asymptomatic, non-uraemic volunteers. Dialysis patients had significantly higher triglyceride and VLDL cholesterol concentrations and lower HDL cholesterol and smaller LDL peak particle diameters. PD patients had significantly higher total cholesterol, glycated haemoglobin and fasting blood glucose levels with smaller LDL peak particle diameters (24.4 [0.1] vs 24.8 [0.1 nm] than HD. Both groups showed significant negative correlations between plasma triglyceride and LDL peak particle diameter, and positive correlations between HDL cholesterol and LDL peak particle diameter. All the PD patients expressed the B phenotype (LDL peak diameter ± 25.5 nm) compared to 73% of HD patients. This study demonstrates that HD and especially PD patients have atherogenic lipid profiles which are associated with a predominance of small dense LDL particles and the highly atherogenic LDL subclass phenotype B.     

Management of bacterial peritonitis and exit‐site infections in continuous ambulatory peritoneal dialysis*

SUMMARY: Peritonitis and exit‐site infections remain the most important limitations to the delivery of continuous ambulatory peritoneal dialysis (CAPD). Contamination of the peritoneum, from endogenous or exogenous sources, is responsible for most peritonitis episodes. Patients usually present with a cloudy bag, although other causes should be distinguished. Clinical suspicion of peritonitis should be followed rapidly by microbiological examination and empirical treatment. Microbiological confirmation allows for subsequent treatment based on sensitivities. Other interventions such as catheter removal may be appropriate in some patients. Exit‐site infections should also be identified and treated early. Peritonitis may be further prevented by adequate exit‐site care, hygienic methods, and techniques to minimise early contamination of the exit site. Mupirocin may also have a role in preventing infections caused by Staphylococcus aureus.     

Pressure stability of nasal CPAP and bilevel devices

Summary Question of the study   Nasal continuous positive airway pressure (CPAP) prevents collapse of the upper airway during sleep in patients with obstructive sleep apnea provided that a positive transmural pressure can be maintained during inspiration. We examined pressure-flow characteristics in seven CPAP and bilevel devices during spontaneous breathing.
Methods   The CPAP devices were set to a pressure level of 9.8  hPa (10  cm H₂O) and adapted to a pneumotachograph using a standard CPAP hose and an outlet valve. We continuously measured flow, volume and pressure during resting ventilation and increasing voluntary hyperventilation and analysed the dependence of the variables on a breath-to-breath basis.
Results   Mean CPAP pressures differed between the devices (9.9 – 10.6  hPa) despite the same settings. In all machines pressure fell during inspiration to 8.4 – 9.8  hPa and increased during expiration to 11.1 – 11.7  hPa. This effect increased with higher flow rates. Maximum expiratory pressures rose to 12 – 19  hPa at peak flow rates of 2 l/s, mean expiratory pressures to 9.5 – 16  hPa. Inspiratory pressures dropped to 8.5 – 4.5  hPa (minimum) and 10.5 – 6.0 (mean). Bilevel devices showed a higher stability than CPAP devices. Pressure swings during the respiratory cycle increased the additional work of breathing.
Conclusions   Due to differences in mean and effective CPAP levels CPAP devices are not simply exchangeable but should be individually adapted. Patients with higher minute ventilation might benefit from more stable CPAP machines. The impact on patients' compliance remains to be evaluated.     

Modified Ultrafiltration Attenuates Dilutional Coagulopathy in Pediatric Open Heart Operations

Background. Extreme hemodilution caused by relatively large prime volumes required for cardiopulmonary bypass in infants causes a dilutional coagulopathy, characterized by low concentrations of fibrinogen and other circulating coagulation factors. Modified ultrafiltration results in hemoconcentration and is associated with decreases in postoperative bleeding and transfusion requirements in children. This study was undertaken to quantify the effect of modified ultrafiltration on concentrations of fibrinogen, plasma proteins, and platelets in infants and small children.

Methods. Twenty patients less than 15 kg were studied. Cardiopulmonary bypass circuits were primed with crystalloid solutions. Red blood cells were added during cardiopulmonary bypass for hematocrits less than 15%. Colloid solutions were not administered. Concentrations of fibrinogen, plasma proteins, and platelets, and hematocrit were measured before cardiopulmonary bypass, before modified ultrafiltration, and after modified ultrafiltration.

Results. Modified ultrafiltration was associated with significant (p < 0.001) increases in hematocrit (19% ± 6% to 31% ± 9%), fibrinogen (65 ± 29 to 101 ± 45 mg/dL), and total plasma proteins (2.7 ± 0.3 to 4.9 ± 0.7 g/dL), but no change (p = 0.129) in platelet count.

Conclusions. We conclude that modified ultrafiltration significantly attenuates the dilutional coagulopathy associated with cardiopulmonary bypass in infants.