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This study numerically simulated and investigated the flow field characteristics of a typical dual-pulse solid rocket motor with a soft pulse separation device through thermal insulation ablation under high-temperature dual-pulse erosion. The ablation rate of ethylene -propylene-diene monomer (EPDM) insulator was measured after the experiment. Experimental results were analyzed through scanning electron microscopy and microcomputed tomography. The ablation mechanism of the EPDM insulator under the operation conditions of a dual-pulse solid rocket motor was evaluated by analyzing the results. The results reveal that the internal flow field of the motor with a soft pulse separation device is uniform. The original charred layer existing on the EPDM insulator surface in the first pulse combustor is the decisive factor affecting the final ablation rate of the dual-pulse motor during the second pulse operation, and the ablation characteristic region is easily formed with the exfoliation of the charred layer. The ablation rate difference of the insulator increases with gas velocity.

Background In complex injuries, external fixation device represents a challenge to maintain negative-pressure wound therapy (NPWT). In this trial, we compared a combination of bone wax and colostomy paste versus bone wax alone to seal NPWT around external fixation devices. Methods Debridement surgeries of limbs with open fracture and large soft tissue defect need NPWT to be applied around the external fixation devices were randomized into two groups. The seal between external fixation devices and the drape was established using either bone wax first and then reinforced with colostomy paste or bone wax alone. The primary outcome was seal failure within 3 days of debridement. Secondary outcomes included the number of seal failure per debridement surgery and the time spent in repairing the seal within 3 days. Results A total of 56 debridement surgeries were enrolled: 28 to the bone wax/colostomy paste group versus 28 to the bone wax control group. One patient in the control group died 1 day after the first debridement surgery. One patient in the bone wax/colostomy paste group was transferred to other hospitals within 3 days. The final analysis included 27 debridement surgeries in the bone wax/colostomy paste group and 27 debridement surgeries in the control group. The rate of seal failure (defined by loss of negative pressure at anytime within 3 days) was 81.5% (22/27) in the control group versus 11.1% (3/27) in the bone wax/colostomy paste group (p χ2 test). The bone wax/colostomy paste group also had significantly lower number of seal failures per debridement (median of 0 vs. 2; p = 0.004), and shorter time spent in repairing the seal (median of 0 vs. 18 min; p Conclusions Using bone wax followed by colostomy paste to seal NPWT around external fixation devices reduces seal failure.

Both the environmental and the ecological protection are key issues in the sustainable development of tourism. As a well-known world natural and cultural heritage, intensive study about the environment of Jiuzhaigou scenic spot has been launched since China's natural landscape protection. The field of low-carbon tourism is starting to be explored in China, and this article uses the life cycle assessment theory to evaluate the footprint of Jiuzhaigou. We find that the air quality is closely related to the number of tourists. Therefore, to maintain the environment of Jiuzhaigou, the number of tourists is proposed to restrict. The contribution of this paper is to provide pricing theory for attracting potential tourists and to give a theoretical basis for controlling the number of tourists in Jiuzhaigou Scenic Area.

The strategies concerning modification of the complex immune pathological inflammatory environment during acute spinal cord injury remain oversimplified and superficial. Inspired by the acidic microenvironment at acute injury sites, a functional pH-responsive immunoregulation-assisted neural regeneration strategy was constructed. With the capability of directly responding to the acidic microenvironment at focal areas followed by triggered release of the IL-4 plasmid-loaded liposomes within a few hours to suppress the release of inflammatory cytokines and promote neural differentiation of mesenchymal stem cells in vitro, the microenvironment-responsive immunoregulatory electrospun fibers were implanted into acute spinal cord injury rats. Together with sustained release of nerve growth factor (NGF) achieved by microsol core-shell structure, the immunological fiber scaffolds were revealed to bring significantly shifted immune cells subtype to down-regulate the acute inflammation response, reduce scar tissue formation, promote angiogenesis as well as neural differentiation at the injury site, and enhance functional recovery in vivo. Overall, this strategy provided a delivery system through microenvironment-responsive immunological regulation effect so as to break through the current dilemma from the contradiction between immune response and nerve regeneration, providing an alternative for the treatment of acute spinal cord injury., Inflammatory responses determine the pathological course of spinal cord injury. Here, the authors report on pH responsive fibers for triggered release of IL-4 plasmid liposomes and sustained release of nerve growth factor to regulate the immune response and promote nerve regeneration to enhance functional recovery.

Big infectious diseases do harm to the whole society and it is highly crucial to control them on time. China has successful experience of launching reimbursement policy to control big infectious diseases, Severe Acute Respiratory Syndromes (SARS), efficiently. By evolution model, this article illustrates the efficiency of big infectious disease reimbursement policy in China. On one hand, the number of infected persons decreases under big infectious disease reimbursement policy in China. On the other hand, the total expenditures to cure also under control. In summary, big infectious disease reimbursement policy in China can support as an efficient example to cope with big infectious diseases.

The main obstacle of artificial heart in extending its applications in clinic has been its over high price rather than technical property. The new generation of artificial heart must enable the patients to be able to afford it. The author's permanent maglev pumps, both VAD (ventricular assist device) and TAH (total artificial heart), reduce their price to lower than 10 USDs, ca.1/10 of the third generation of artificial heart electric maglev pump. Moreover, the permanent maglev pump not only retains all the advantages of the electric maglev pump, but also has many innovations: its impeller vane was designed according to the streamlines in the pump, so that the blood damage was reduced as low as possible; It can produce either nonpulsatile or pulsatile flow; It can be made in LVAD or TAH, as wish. Besides, it needs no rotor position detector, no electric magnetic push and pull device for rotor suspension, and no feed-back controller for levitation. This is why its costs can remarkably reduced. Animal experiments for up to two months and clinical trial lasted 43 hours of permanent maglev LVAD demonstrated that the performances were excellent and perfect.

Background: To investigate wound healing in 402 calcaneus fracture cases using precise extensive L-shaped incision.Method: We retrospectively analyzed 402 calcaneus fracture cases, involving patients who underwent heel bone reduction and internal fixation, using precise extensive L-shaped incision, at the second hospital of Shanxi medical university between January 2018 and December 2020. Postoperative would healing was evaluated using a self-designed skin margin grading system. Results: The patients experienced osseous healing after the surgery. A Maryland foot score of ≥90% was considered excellent. The skin margins from Grade I, II, III injuries healed spontaneously after dressing change. However, Grade IV injuries healed after debridement or removal of internal fixation.Conclusions: The precise extensive L-shaped incision, used in this study, allowed for fewer postoperative wound complications and lower incidence of skin necrosis.

Big infectious diseases do harm to the whole society, and it is highly crucial to control them on time. The major purpose of this article is to theoretically demonstrate that the Chinese government’s intervention in large-scale infectious diseases is successful and efficient. Two potential strategies were considered: strategy 1 was infectious disease without government intervention, and strategy 2 was infectious disease with government intervention. By evolution model, this article illustrates the efficiency of big infectious disease reimbursement policy in China. Without government reimbursement, this article finds that high expenditures accelerate the disease infection. The number of infected persons decreases under big infectious disease reimbursement policy in China. The higher the treatment costs, the more important the government intervention. Big infectious disease reimbursement policy in China can serve as an efficient example to cope with big infectious diseases.

To explore the effect and mechanism of Qingfei Mixture (清肺合剂), a Chinese medicine, in treating mycoplasma pneumonia (MP) in MP patients and rat model A total of 46 MP children with phlegm heat obstructing Fei (Lung) syndrome were randomly assigned to two groups by the method of random number table, with 23 children in each group. The control group was treated with intravenous infusion of azithromycin; the treatment group received intravenous infusion of azithromycin and oral administration of Qingfei Mixture. The treatment course was 7 days. Major symptoms and minor symptoms were observed and scored before and after treatments. A rat model of MP was also established. A total of 120 wistar rats were randomly divided into 5 groups: a normal group, infection group, Qingfei Mixture treatment group, azithromycin treatment group, and Qingfei Mixture + azithromycin treatment group. Each group contained 24 rats, from which every 6 were euthanatized 1, 3, 7 and 14 days after infection. MP DNA in pulmonary tissue homogenates was detected using real-time fluorescence quantitative polymerase chain reaction. Pathology was assessed after hematoxylin (HE) staining and lung tissue pathology scores were determined in pulmonary tissue. Transmission electron microscopic detection and electronic image analysis were performed on lung tissue 3 days after infection. Interleukin (IL)-17 was detected in serum using enzymelinked immunosorbent assay (ELISA) 7 days after infection. In the clinical study, both control and the treatment group showed improved results on removing symptoms of phlegm heat syndrome compared to the control group (P

Currently, carbon nanotubes (CNTs) are used as popular fillers for enhancing the composite insulation materials in solid rocket motors (SRMs). While the mechanical properties of the char layer are enhanced by their use, the thermal insulation performance is reduced. This study proposes to solve this problem by pre-coating CNTs. The surface of CNTs was coated with a carbon layer using chemical vapour deposition (CVD), resulting in an ethylene propylene diene monomer (EPDM) composite insulation material reinforced with coated-CNTs. Furthermore, the ablation experiments were examined using oxyacetylene ablation test (OAT). The experimental results show that, compared with that of the CNTs formulation, the thermal conductivity of the coated-CNTs formulation is significantly reduced. On the other hand, for the coated-CNTs formulation, the temperature response time of the back of the material is increased, while the heating rate and maximum temperature are greatly reduced. In addition, the char layer of the coated-CNTs formulation has better compression resistance compared with that of the CNTs formulation. It is concluded that the coated-CNTs not only improve the thermal insulation performance by reducing the thermal conductivity of the material, but also promote the particle erosion resistance of the insulation material by enhancing the strength of the char layer.

Streamlines in mixed-flow impeller were deduced by solving partial differential equations of continuity, motion and energy; they could be simplified to be logarithmic spiral and parabola in vertical and horizontal sections respectively. Then a mixed-flow impeller was designed and manufactured, its vane had a logarithmic spiral and its shroud had a parabola form. Computational fluid dynamics (CFD) demonstrated that the streamlines in the impeller were coincided with the vane and shroud; particle image velocimetry (PIV) exhibited also that the streamlines in vane channel were really logarithmic spiral at the designing point of pumping flow rate and pressure head. It concludes that both theoretical and experimental methods presented in this paper are informative and convincing, and thus are worthy to be investigated further.

Permanent maglev has been since long recognized to be unstable because of Earnshaw's theory, which theoretically proved that permanent maglev can not achieve stable equilibrium in static state. How about that in dynamic state, for example, about a rotator, nobody has given an answer until now actually. A permanent maglev pump and a permanent maglev turbine have been developed, by using a patented permanent magnetic bearing developed by the author. Experiments demonstrated, there is a critic speed either in the pump or in the turbine, under which the rotors in the pump and the turbine have a maximal eccentricity being possible to reach the gap between the rotor and the stator. That means the rotors have contact with the stators occasionally, and thus the rotor is not suspended. In case the rotating speed is higher than this critic speed, the rotors' eccentricity will be remarkably smaller than the gap between the rotor and the stator, that is to say the rotor is stably levitated. Further investigation exhibtes that at the critic speed a so-called gyro-effect is generated which stabilizes the rotor, just like a gyro standing over a ball, if the rotating speed is large enough it can be stable over the ball. The critic speed, essentially to be minimal stable speed of the rotor, depends on the rotating inertia of the rotor and the bearing force, the larger the inertia and the larger the force, the lower the critic speed. Conclusively, a route chart to stabilization of permanent maglev rotator has been clear: in static state, permanent maglev is unstable (Earnshaw's theory); as the rotating speed gradually increases but not up to a critic speed, the permanent maglev rotator is also unstable; in case that the speed equals or is larger than this critic speed, the permanent maglev rotator is suspended stably because of gyro-effect; the critic speed is affected by rotating inertia of the rotor and the bearing force, by larger inertia and larger bearing force, the critic speed will be smaller.

With the development of heart pumps, more and more commercial artificial heart have been applied to clinic use. However, most of the products produce some discomfort to human body, which coudn’t meet the physiological requirements of patients. Therefore, further improvement and enhancement for these products are needed and adopting bionic control using neural network is an effective method to improve heart pumps’ comfort. A neural network model was established in this paper according to the relationship among the pressure head, the motor power and the rotating speed using using Based on neural network software Neuroshell2. Based on the defined appropriate activation function, a lot of data were studied and trained for optimization of the neural network model and determination of weights and deviations . Finally, the bionic control system was built and the experiments of the control system were conducted. The results reveal that the error measured values and the actual values was within 5% and acceptable and that the bionic control system using neural network is proved to improve the the comfort after implantation of blood pumps.

The authors’ former works demonstrated that a passive magnetic (PM) rotator supported merely by PM bearings has a minimal speed, above which it can stabilize its equilibrium, under the function of a so-called Gyro-effect. It is unclear, however, by which factors is this minimal speed determined. This paper investigated the factors affecting the minimal stable speed of permanent maglev rotator, namely, the rotating inertia and PMB force. Two novel permanent maglev turbine models were designed: Model A---one stator and three rotors which have the same size but different rotational inertias; Model B---one rotor and one stator, but the stator has been devised with three different passive magnetic bearings: 1. a pair of small magnetic rings; 2. a pair of big magnetic rings; and 3. both of the two pairs of magnetic rings. Four Hall sensors distributed evenly at the turbine’s stator were used to detect the rotor’s eccentricity, and the speed sensor measured rotating speed. The calculated models of rotor’s eccentricity were established respectively for the two turbine models; the rotor’s eccentricity measuring system was built up and the rotor’s eccentricity of the two turbines was measured. The experimental data demonstrated that the rotational inertia of three rotors in the model A is 6.293×10-5 kg•m2, 1.074×10-4 kg•m2 and 2.081×10-4 kg•m2 respectively, and the corresponding minimal speed for suspension are 4597rpm, 3030rpm and 2222rpm respectively; in the model B, the magnetic force between the stator and rotor in the three cases is 92.12N, 123.48N, 212.66N respectively, corresponding to the minimal speed for suspension---3730rpm, 3120rpm and 2195rpm respectively. The results exhibited that same as the permanent maglev heart pump, permanent maglev turbines also have gyroscopic effect, which makes the rotors maintain stable suspension. And the minimal speed for suspension has a negative correlation with the rotor’s rotational inertia, namely, the bigger the inertia of the rotor, the smaller the required speed for suspension; the minimal speed for suspension also has a negative correlation with the magnetic force between the stator and rotor, that is, the larger the magnetic force, the smaller the rotating speed for suspension. Smaller minimal speed means better stability of the system, thereafter larger inertia or larger bearing force means better stability; besides, larger difference between minimal speed and performance speed of the rotator means better stability, it’s suggested permanent maglev be applied in high speed rotary machines.

R&D of artificial heart has lasted over 50 years, now both rotary and diaphragm pumps can assist the circulation of the patients several years, after solving many technical problems. In rotary heart pumps, the basic technical problems have been the implantability, the compatibility, the pulsatility, the durability, the biventricular assist, the automatic measurement, the bionic control and the thrombus formation. This paper summarizes the author’s contributions in solving these problems and shares the novelties of some Chinese rotary heart pumps with the readers. The energy supply is one of the most important unsolved problems in rotary heart pumps; the present methods either by use of electric wire cross the skin or using transcutaneous inductive system are problematic because they are neither convenient nor reliable.

All existing left ventricular assist devices (LVADs) need inlet and outlet connecting con-duits and the assist pumping blood flows through the bypass circuit from left ventricle to aorta. It will result in some most likely sites of thrombosis and brings about physiological dis-turbance to natural circulation, as well as addi-tional need for anatomic occupation in chest. The author developed a trans-apical and cross-valvular intra-ventricular axial pump and an aortic valvo- pump to solve these problems. The intra-ventricular pump weighing 53g has a length of 115mm and its largest O.D. is 13mm. The motor is 60mm long and the pump 55mm. In both sides of motor, specially designed needle bearings are devised and a purge system keeps the motor together with bearings working in sa-line. The device is inserted into the ventricle by trans-apex and then into the aorta by cross-valve. It is used for recovery therapy or bridge to transplantation. The bearing-less valvo-pumps have an outer diameter of 21mm, 23mm or 25mm for patients with different body weights. The weight of the devices is 27g, 31g or 40g respectively. Used for destination therapy it can be easily sewed onto the aortic valve annu-lus, delivers blood from ventricle to aorta di-rectly. These two novel mini LVADs may reduce thrombosis risk in clinical applications.

Because of severe hemolysis, especially on producing pulsatile flow by changing the rotating speed of the impellers, the traditional centrifugal pump was rarely used for long-term support of the failing heart. We therefore developed a motor driven pulsatile implantable impeller pump. The pulsatility was achieved by changing the rotating speed via introducing a square waveform voltage into the motor coil. The impeller vane was designed to have both radial and axial curves according to the stream surface and stream lines to reduce the thrombosis and hemolysis. Nine calves weighing 80 to 100 kg were used. With the calves under endotracheal general anesthesia, left posterolateral thoracotomy was performed to connect the inflow tube with the left atrial appendage and to anastomose the outflow tube with the descending aorta. The calves usually awoke and stood up within hours after discontinuation of anesthetics. Within 7 days, continuous monitoring of electrocardiogram, systemic and pulmonary arterial pressures, and central venous pressure were performed to adjust the pump flow to 40% to 50% of the cardiac output. During the survival of 4 to 54 days (mean 16.3 +/- 19.3 days with two calves surviving longer than 1 month), no significant deterioration of liver or renal function was noted. Because of bleeding, hemoglobin reduced from 11.4 +/- 1.8 to 9.0 +/- 1.3 g/dl, and the hematocrit decreased from 34.5 +/- 4.7 to 26.7 +/- 4.6%. No significant changes of free hemoglobin were noted. In our results, the device revealed competent pulsatile function without severe blood damage or organ dysfunction.

We propose a simple and concise mathematical method based on the Fraunhofer approximation to analyze the imaging characteristics of slit for broadband light sources. Taking Gaussian-shaped ultra-short laser pulse for example, we investigated the diffraction imaging characteristics of ultra-short light sources through a single-slit and a double-slit. We deduced the mathematical expressions of the intensity distribution of far-field diffraction, and conducted numerical calculation and analysis. It turns out the pulse width of the ultra-short light source plays an important role in the diffraction imaging characteristics of slit. We also provide a quantitative criterion to measure the deviation in terms of far-field diffraction intensity distribution between broadband light source and the ideal monochromatic light source.

A quantitative evaluation of shear stress-related hemolysis in centrifugal blood pumps with different impeller designs has been investigated. Computational fluid dynamics (CFD) is applied to track the shear stress history of the streamlines of red cells. The power law model of the relations among the hemolysis, shear stress and exposure time is used to evaluate the hemolysis in the pumps. hemolysis tests are also conducted to verify the estimations. Both the estimations and experimentally measured hemolysis levels show that the hemolysis in the streamlined impeller pump developed by the authors is lower than the pump with straight-vane under the same boundary conditions. The approach is proved to be acceptable and practical to predict hemolysis levels of blaad pumps.

A pulsatile impeller total heart was developed, which consists of two impeller pumps and a d.c. motor. As the motor changes its rotating speed periodically, both pumps eject the blood flow simultaneously. To evaluate its blood compatibility, the device and sarns roller pumps were compared in two series of acute biventricular assist experiments in four and three pigs, repectively. The experimental conditions were controlled to be as equal as possible. The experiments lasted 6 hours. Blood sampling was drawn preoperatively, at the beginning of the pumping and every 2 h postoperatively. Red blood cells (RBC), white blood cells (WBC), platelets (PLT), hematocrit (HCT), hemoglobin (HB), free hemoglobin (FHB) and lactate dehydrogenase (LDH) were measured. The results demonstrated that there was no significant blood damage caused by impeller total heart and the clinically used roller, and that the pulsatile impeller total heart is suitable for chronic animal experiments.

A pulsatile implantable impeller pump was tested as a left ventricular assist device in five calves. The experiments lasted for 4-11 days. Death or termination was mainly due to respiratory complications or bleeding, irrelevant to the pump itself. As indicators of haemolysis, thrombogenesis, renal and hepatic functions, free haemoglobin( FHb), haematocrit (Hct), platelet number (Plt), lactate dehydrogenase (LDH), blood urea nitrogen (BUN), creatinine, serum glutamic oxalacetic transaminase (GOT) and total bilirubin were measured preoperatively, at the beginning of the pumping (pump on), six hours later and every day thereafter. The data indicated that the pump caused no severe blood damage or organ dysfunction. Thus, the feasibility of a pulsatile centrifugal pump was demonstrated. The pump with its driver weighs 110 g and is capable of delivering a blood flow up to 8 l/min against 100 mmHg mean pressure.

Based on the feature of the second-order FM halftone dots and the interaction feature among ink, paper and air, a spectral prediction model for the second-order FM halftone prints for the spectral Neugebauer random mixing model and dot-on-dot mixing model is developed by using a weighting factor to signify the correlation proportion of two models. The new spectral prediction model also includes the Yule-Nielsen effect by taking into account ink spreading in all ink superposition conditions. We create an ink spreading function for each superposition condition to indicate the difference of ink spreading for ink dots printing on different superposition, which maps nominal to effective dot surface coverage. Our results shown that in the ink jet printing, the mean and max ΔE difference between measured and predicted values are 2.90 and 7.26, smaller than the difference predicted by the model that is not taken into account ink spreading, which are 5.52 and 12.81. The prediction accuracy is considerably improved by the new model.

All existing left ventricular assist devices(LVADs) need inlet and outlet connecting conduits and the assist pumping blood flows through the bypass circuit from left ventricle to aorta. It will result in some most likely sites of thrombosis and brings about physiological disturbance to natural circulation, as well as additional need for anatomic occupation in chest. The author developed a trans-apical and cross-valvular intra-ventricular axial pump and an aortic valvo-pump to solve these problems. The intra-ventricular pump weighing 53 g has a length of 115 mm and its largest O.D. is 13 mm. The motor is 60 mm long and the pump 55 mm. In both sides of motor, special designed needle bearings are devised and a purge system keeps the motor together with bearings working in saline. The device is inserted into the ventricle by trans-apex and then into the aorta by cross-valve. It is used for recovery therapy. The bearing-less valvo-pump has an outer diameter of 21 mm, 23 mm or 25 mm for patients with different body weights. The weight of the device is 27 g, 31 g or 40 g respectively. Used for destination therapy it can be easily sewed onto the aortic valve annulus, delivers blood from ventricle to aorta directly. These two novel mini LVADs may reduce thrombosis risk in clinical applications.

Despite the progresses in developing pulsatile impeller pump and impeller total heart, as well as in applying streamlined impeller vanes, the best results in application of artificial heart pumps have been achieved by nonpulsatile univentricular assist pump with straight impeller vanes until now. It seems all efforts and successes have been done in vain because artificial heart rejects HiTech! This paper recalls some important achievements in R&D of artificial heart in past 25 years and shares author's experiences with the readers.

The impeller total heart was developed and published several years ago but its in-vivo evaluations could only be made recently. Originally, the device was designed for long-term implantation. As the first step, however, it was used this time in acute biventricular assistance, to demonstrate the blood compatibility of the pumps, and to demonstrate the feasibility of an impeller type centrifugal total heart. The haematological measurements made during the experiments indicated that no remarkable blood damage occurred and that all the biochemical datums remained relatively unchanged. Because the centrifugal pump has been considered, until now, to be able only to produce a nonpulsatile flow, its applications have been limited mainly to assist the heart. This first assessment of an impeller total heart reported here will open the application area of centrifugal pumps to include cardiovascular surgery.

Permanent maglev rotator in a rotary machine could be stabilized according to the author’s experiences, by use of a non-PM (permanent magnetic) force acting together with the PM force, and a non-PM bearing functioning together with the PM bearing, or a so-called gyro-effect which can stabilize all rotators including permanent maglev rotator. This paper presents both axially and radially driven permanent maglev centrifugal heart pumps, as well as a permanent maglev turbine machine and an industrially used permanent maglev centrifugal pump. In all this devices permanent maglev rotators achieve stable equilibrium by different approaches described in detail. Finally, the principle exhibition of gyro-effect and the route chart to stabilization of permanent maglev rotator are presented .

The traditional centrifugal pump may induce excessive hemolysis, especially, when the impeller changes its rotating speed to produce a pulsatile flow, even though pulsatility is poor. We therefore developed a motor-driven pulsatile implantable impeller pump. Pulsatility was achieved by changing the rotating speed via the introduction of a square waveform voltage into the motor coil. The impeller vane was designed to have both radial and axials curve according to the stream surface and stream lines to reduce thrombosis and hemolysis. Seven calves, weighing 80–100 kg, were used. With the calves under endotracheal general anesthesia, left posterolateral thoracotomy was performed to connect the inflow tube with the left atrial appendage and to anastomose the outflow tube with the descending aorta. The calves usually awoke and stood up within hours after discontinuation of the anesthetics. Continous monitoring of electrocardiogram, and of systemic and pulmonary arterial pressures and central venous pressure, was performed for 6.7 ± 2.2 days. During the course, the pump flow was adjusted to 40% of the cardiac output. No significant deterioration of liver or renal function was noted. Hemoglobin was reduced from 11.6 ± 1.8 to 8.7 ± 1.3 gm/dl and hematocrit from 34.7 ± 4.7% to 25.9 ± 4.6%. No significant changes of free hemoglobin were noted (preoperative 4.59 ± 1.44 to final 4.44 ± 1.59 mg/dl). Our short-term results showed that the device had competent pulsatile function without causing severe blood damage or organ dysfunction. Long-term observation is required before the performance of clinical trials.

The measurement of blood flow from an assist ventricle is important but sometimes difficult in artificial heart experiments. Along with the development of a pneumatic cylinder-piston driver coupled with a ventricular assist device, a simplified method for measuring pump flow was established. From driving parameters such as the piston (or cylinder) displacement and air pressure, the pump flow could be calculated by the use of the equation of state for an ideal gas. The results of this method are broadly in agreement with electromagnetic and Doppler measurements.

Hemolysis and thrombosis have been considered as the main limitations of the impeller pump and other centrifugal pumps to total heart ap plications. One of the solutions is to choose the impeller shroud and vane ac cording to the stream surfaces of blood flow, so as to vanish the turbulence and stagnation which cause the hemolysis and thrombosis, respectively, in the pump. This paper describes the method of deducing the stream surfaces to gether with the velocity distributions in the impeller from the fundamental dynamical equations, and presents a prototype design of the impeller total heart which promises to be an ideal alternative to the problematic diaphragm total heart.

A simple, portable, reliable and noise-free pneumatic driver has been developed. It consists of a linear motor attached to a cylinder piston, in one unit. The motor coil is directly wound on the cylinder, and the permanent magnet is fixed to the piston. As a continuous voltage square wave is applied to the coil, the cylinder reciprocates on the piston periodically, producing air pressure and vacuum alternately. In conjunction with a locally made diaphragm pump, the driver was tested in vitro and in vivo. Results demonstrated that the device could drive the diaphragm pump and so support the circulation of an experimental animal. The driver weighs 12 kg. For 200 mmHg air pressure and -80 mmHg vacuum the power consumed is 30 W. Its noise is about 30 dB, less than that of an artificial valve and pump.