Artículos de revistas sobre el tema "Unstable charge pump"

In this article, the effect of dust charge fluctuations on the parametric upconversion of a lower hybrid wave into an ion cyclotron wave and a side band wave in a two-ion species tokamak plasma is studied. When the oscillatory velocity of plasma electrons is a few percent of the sound velocity, the lower hybrid wave becomes unstable and decays into two modes: an ion cyclotron wave mode and a low frequency lower hybrid side band wave. Furthermore, a ponderomotive force by a lower hybrid pump and a side band wave is exerted on the existing electrons, which drives the ion cyclotron decay mode. The presence of negatively charged dust grains and their shape, size, radius, and density influence the instability. The growth rate of instability is calculated by considering typical existing D–T (Deuterium–Tritium) dusty plasma parameters, and it is observed that the growth rate increases with the relative density of dust grains, number density of dust grains, oscillatory velocity of electrons, and amplitude of pump waves. However, the normalized growth rate increases with the unstable wave frequency, and it also increases as we increase the ratio of deuterium to tritium density. Here, the growth rate decreases with the increase in the size of dust grains and electron cyclotron frequency. The theoretical results summarized in the present study are able to efficiently elaborate the complexity produced in plasma properties in a tokamak due to the dust–plasma interactions, which are briefly discussed here.

AbstractIntroduction:Unexpected disasters, such as earthquakes or fires, require preparation to address knowledge gaps that may negatively affect vulnerable patients. Training programs can promote natural disaster readiness to respond and evacuate patients safely, but also require evidence-based information to guide learning objectives.Problem:There is limited evidence on what skills and bedside equipment are most important to include in disaster training and evacuation programs for critically ill infants.Methods:An expert panel was used to create a 13-item mastery checklist of skills for bedside registered nurses (RNs) required to successfully evacuate a critically ill infant. Expert nurses were surveyed, and the Angoff method was used to determine which of the mastery checklist skills a newly graduated nurse (ie, the “minimally competent” nurse) should be able to do. Participants then rated the importance of 26 commonly available pieces of bedside equipment for use in evacuating a hemodynamically unstable, intubated infant during a disaster.Results:Twenty-three emergency department (ED) and neonatal intensive care unit (NICU) charge RNs responded to the survey with a mean of 19 (SD = 9) years of experience and 30% reporting personal experience with evacuating patients. The skills list scores showed an emphasis on the newly graduated nurse having more complete mastery of skills surrounding thermoregulation, documentation, infection control, respiratory support, and monitoring. Skills for communication, decision making, and anticipating future needs were assessed as less likely for a new nurse to have mastered. On a scale of one (not important) to seven (critically important), the perceived necessity of equipment ranged from a low of 1.6 (breast pump) to a high of 6.9 (face mask). The individual intraclass correlation coefficient (ICC) of 0.55 showed moderate reliability between raters and the average team ICC of 0.97 showed excellent agreement as a group.Conclusion:Experts rated the ability to manage physiological issues, such as thermoregulation and respiratory support, as skills that every nurse should master. Disaster preparedness activities for nurses in training may benefit from checklists of essential equipment and skills to ensure all nurses can independently manage patients’ physiologic needs when they enter the workforce. Advanced nursing training should include education on decision making, communication during emergencies, and anticipation of future issues to ensure that charge and resource nurses can support bedside nurses during evacuation events.

The unsteady flow process of waterjet pumps is related to the comprehensive performance and phenomenon of rotating stall and cavitation. To analyze the unsteady flow process on the unsteady condition, a computational domain containing nozzle, impeller, outlet guide vane (OGV), and shaft is established. The surface vortex of the blade is unstable at the valley point of the hydraulic unstable zone. The vortex core and morphological characteristics of the vortex will change in a small range with time. The flow of the best efficiency point and the start point of the hydraulic unstable zone on each turbo surface is relatively stable. At the valley point of the hydraulic unstable zone, the flow and pressure fields are unstable, which causes the flow on each turbo surface to change with time. The hydraulic performance parameters are measured by establishing the double cycle test loop of a waterjet propulsion device compared with numerical simulated data. The verification results show that the numerical simulation method is credible. In this paper, the outcome is helpful to comprehend the unsteady flow mechanism in the pump of waterjet propulsion devices, and improve and benefit their design and comprehensive performance.

In this article, the influence of rotor–stator distance on the pump performance and rotor–stator interaction strength within mixed-flow centrifugal pump was investigated based on numerical calculation and test verification. Firstly, the performances of mixed-flow centrifugal pumps with two different rotor–stator distances were obtained and compared with the numerical results, which confirms the high accuracy of the numerical simulation. Next, the performances of mixed-flow centrifugal pumps with five different rotor–stator distances were compared and analyzed. It was found that the hydraulic performance of the mixed-flow centrifugal pump varies slightly as the rotor–stator distance increases. The mean values of the standard deviation of the head and efficiency of the mixed-flow centrifugal pump at each rotor–stator distance under full flow conditions are only 0.16 m and 0.11%, respectively. Then, the strengths of the rotor–stator interaction with different rotor–stator distances were analyzed. It was found that the strengths of the shock interaction, the wake interaction, and the potential interaction were all reduced with increasing rotor–stator distance. Moreover, when the rotor–stator distance is 1.5 mm, the pressure distribution in the circumferential direction of the rotor–stator interference zone shows obvious unstable characteristics: the pressure change amplitude is significantly greater than the other rotor–stator distance of the pressure change amplitude, the maximum and minimum pressure amplitude difference being 56.9 kPa, and with the increase in the rotor–stator distance, the maximum and minimum pressure amplitude difference gradually decreases, with an average value of 32.3 kPa. These findings could provide useful insight into prospects for the improvement of the operational stability of mixed-flow centrifugal pumps, and the results of this study can be extended to all centrifugal pumps using diffusers in the form of vanes as the pressure chamber, which has strong practical application and theoretical value.

Introduction. The preliminary study of new developed pumps for circulatory support on the hydrodynamic circulation model is an important step in the process of their designing. Hydrodynamic circulation models that can closely imitate cardio – vascular system are important to defi ne the range of effective functioning of the pumps under normal and heart disease conditions which is of great importance for defi ning the mode of these pumps in real clinical conditions.The aim of study is to create a new hydrodynamic circulation model of the systemic circulation to study the processes of interaction of heart left ventricle and continuous – fl ow pumps.Materials and methods. The main components of the mock circulation model (arterial and venous blocks) are designed as closed reservoirs with an air bag providing the necessary elasticity value of these reservoirs. The heart left ventricle was simulated with an artifi cial heart ventricle with a pneumatic drive Sinus-IS which allows to change its options in a wide range. As a test pump we used the fi rst native implantable axial pump VISH – 1. In the course of research we made the registration and recording of the basic hemodynamic parameters (pressure, fl ow) with a multichannel module Pumpax for the measurement of pressure parameters.Results. The designed circulation model allows to adequately reproduce the main hemodynamic parameters of the circulatory system in normal (arterial pressure – 110/77 mmHg, left atrium pressure – 7 mmHg and cardiac output – 4.2 l/min) and heart failure conditions (arterial pressure – 79/53 mmHg, left atrium pressure – 15 mmHg and cardiac output – 3.1 l/min). On the circulation model the interaction of heart left ventricle and continuous-fl ow pump in heart failure simulation was studied. The dynamics of the main circulation fi gures is shown under conditions of changing of the pump rotor speed. Meanwhile, the conditions of the closing of aortic valve are identifi ed which is important for theclinical use of this pump. Using a special separately fl exible camera on the pump inlet we modeled phenomena of negative pressure leading to unstable pump operation and reduction of pump fl ow.Conclusion. Characteristics of the developed hydrodynamic circulation model allow us to reproduce parameters of systemic circulation in a wide range and to use it in designing of new pumps for circulatory support.

With the rapid development of industrialization, the excessive use of fossil fuels has caused problems such as increased greenhouse gas emissions and energy shortages. The development and use of renewable energy has attracted increased attention. In recent years, solar heat pump heating technology that uses clean solar energy combined with high-efficiency heat pump units is the development direction of clean heating in winter in northern regions. However, the use of solar energy is intermittent and unstable. The low-valley electricity policy is a night-time electricity price policy. Heat pump heating has problems such as frosting and low efficiencies in cold northern regions. To solve these problems, an exergy analysis model of each component of a phase-change heat-storage coupled solar heat pump heating system was established. Exergy analysis was performed on each component of the system to determine the direction of optimization and improvement of the phase-change heat-storage coupled solar heat pump heating system. The results showed that optimizing the heating-end heat exchanger of the system can reduce the exergy loss of the system. When the phase-change heat-storage tank meets the heating demand, its volume should be reduced to lower the exergy loss of the tank heat dissipation. Air-type solar collectors can increase the income exergies of solar collectors.

Abstract High stability in axial direction is required for rocket pumps operated under extremely low-temperature and high-pressure conditions, turbopumps therefore uses balance piston (BP) system for balancing their axial thrust. The BP system is stable under quasi-static conditions. However, BP system might become dynamically unstable under some condition. Thus it is fundamental for stability evaluation of turbopumps to predict static/dynamic characteristics in axial direction of BP system. Furthermore, we focus on characteristic change by cavitation which often occurs in the pump inlet. In this paper, an experimental study of a model turbopump which had an unshrouded impeller equipped with BP system was carried out. We experimented it with an active magnetic bearing (AMB) test facility in order forcibly to oscillate it with an optional amplitude and frequency. In addition, we examined characteristics of BP system by three-dimensional computational fluid dynamics (3D-CFD) simulations. The results of 3D-CFD simulations were in good agreement with these tendency of BP system, and were effective in predicting its static/dynamic characteristics. Some cases showed that dynamic characteristic of BP system became unstable by growth of cavitation, therefore we suggest that the influence of cavitation must also be considered in the design of turbopump.

The mixed-flow pump is wildly used in industrial and agricultural fields, and the requirements for its stability become more and more restricted with the improvement of the capacities. When the pump is operated under part-loading conditions, unstable characteristic like rotating stall happens and brings intensive vibration and noise. To reveal the internal unstable flow characteristics in mixed-flow pump, unsteady numerical simulation is conducted under different flow rates in the current research. The secondary flow and the vortex induced by the unsteady flow in the pump, which vary with the change of the flow rate, are analyzed according to the simulation results. Pressure fluctuation in different parts of the impeller is numerically predicted and correlated to the rotating stall propagation process. With the reduction of the flow discharge, a critical flow rate (0.6 Qdes in the current model pump) is found related to the rotating stall inception. Unstable vortex structure is found in part of the flow passages of the impeller under the stall inception stage; 0.56 Qdes is the flow rate related to the deep rotating stall under which stable stall vortexes are found in each flow passage of the impeller. Three types of pressure fluctuation characteristics representing different flow field pattern in the impeller are found. When the pump is working at designed flow rate, the pressure fluctuation is regular with the dominant frequency being the rotation frequency fs of the rotor. At the stall inception condition, when the stall core appears in the flow passages of the impeller in turn, the amplitude of the pressure fluctuation is increased and the dominant frequency is changed to a low-frequency signal. When the flow rate is reduced below deep stall condition, owning to the reflux from the guide vane and the intensive rotor–stator interaction, the blade passing frequency of the guide vane fb2 becomes the dominant frequency. Finally, unsteady characteristics of the flow field under stall inception condition are analyzed to demonstrate the propagation process of the rotating stall. The stall vortex is found to propagate from the stalled flow passage to the next, through the tip area of the blade leading edge. During the propagation process, the first vortex shrinks and disappears gradually, while the second vortex grows continuously, and the third vortex shows up at the vanishment of the first stall vortex. This research provides detailed information for the unstable flow especially related to rotating stall evolution with the variation of the operating flow rate of the mixed-flow pump with guide vane.

Abstract Hydropower is a major renewable clean energy and is widely used worldwide. The reversible pump-turbine unit of the pumped-storage power station is able to work in two main operating modes as required by the power grid: turbine-mode for power generation and pump-mode for power storage. In order to absorb unstable energies such as wind and solar energy and improve the quality of the electricity, reversible pump-turbines need to frequently change operating conditions, and experience more start-stops under different operating modes in a short period. The unstable flow during these transient processes will lead to high-level stresses on the structural components of the pump-turbine units. Therefore, it is of great engineering and academic significance to study the flow characteristics and structural characteristics of the unit during the transient processes. This paper has established a numerical calculation model for a prototype reversible pump-turbine unit, has carried out the CFD calculations of the pump-turbine fluid domains during the pump shutdown transient process, and has analysed the corresponding structural dynamic characteristics of the stationary components of the unit with the fluid-structure coupling method. The pressure variation trend of the spiral case outlet during pump shutdown has the same trend as that of the spiral case domain, and the guide vane flow domain. The maximum flow-induced deformation and stress of the stationary structures have a strong correlation with the axial thrust values of the head cover. The maximum deformation occurs at the inner edge of the head cover, and the maximum stress appears in the fillet of the stay vane leading edge. An increase in the number of shutdowns will result in a higher real risk of fatigue damage to the stay vanes. The conclusions obtained are of great value for safe operation, field condition monitoring, fault diagnosis, and predictive maintenance of the pump-turbine units.

Submersible drainage sump pumps work in a highly corrosive environment, forming films with corrosive reaction products on the surface. Pump rotors are high-demand parts, so they are made of quality materials with good wear and corrosion resistance properties such as nodular graphite cast iron. This paper analyses the corrosion behaviour of cast iron used in the manufacture of rotors in three types of wastewaters, with variable pH. Nodular graphite cast iron samples were immersed in wastewater for 30, 60, and 90 days and tested by linear polarisation and electrochemical impedance spectroscopy (EIS). Also, the layers of reaction products formed on the surface of the material were analysed by SEM and EDS. The results showed that nodular cast-iron immersed in wastewater with acidic pH showed intense corrosion, the oxide layer formed on its surface is unstable. Also, the final structure of the product layer is that of a tri-layer with cations and anions absorbed from the corrosion media: the double-electric layer directly connected to the metal surface, an internal layer consisting of ferrous compounds and ferric compounds that control the diffusion of oxygen, an outer layer, and a compact crust of ferric compounds. The change in the pH of the wastewater has a major influence on the corrosion rate of the cast iron, which increases from 356.4 µm/year in DWW-1 (6.5 pH) to 1440 µm/year in DWW-2 (3 pH) and 1743 µm/year DWWW-3 (11 pH) respectively. As can be seen, the experimental study covers the problem of the corrosion behaviour of the pump rotor in various types of wastewaters this aspect is particularly important for the good use of wastewater pumps and to predict possible deviations for the operation of the equipment within the treatment plants.

The runaway oscillation process of the pump-turbine in a high head pumped-storage power plant is usually unstable. The root cause of its instability is still unclear. In this paper, its internal mechanism and the improvement method were studied in depth. First, the flow characteristics in a model pump-turbine during the runaway process at four guide-vane openings (GVOs) were investigated by 3D transient numerical simulations. Then, the energy dissipation characteristics of different types of backflow vortex structures (BFVSs) occurring at the runner inlet and their impacts on the runaway stability were investigated by the entropy production theory. The results show that the location change of BFVSs between the hub side and the mid-span of the runner inlet around the no-load point leads to the sharp change in the energy dissipation rate, which makes the slope of dynamic trajectory positive and the runaway oscillation self-excited. If the occurrence of BFVSs at the hub side is suspended, the runaway process will be damped. Finally, the pump-turbine runner was improved to obtain a wider stable operating range.

The water-collecting well layer of large pump station base plate is constrained by bottom and lateral, and step construction method is used. In view of the characteristics, the simulation is done to study its temperature and stress during construction. Based on a large pump station project and the structural characteristics and construction method of water-collecting well layer, the FEM model is built, and the theories of the 3D-FEM of unstable temperature field and stress field is used to carry out the numerical calculation, which can study change law and distribution of temperature and stress. The results show that the method of step construction can increase concrete cooling during construction, but the heat dissipation potential is difference in different time of day.

Abstract A direct-drive PV pump system based on phase change heat storage is proposed to address the current building energy consumption problem in heating/cooling. The system can solve the problems of unstable solar energy, high battery cost, and short battery service life. Taking a 45m 2 office in Shanghai as the research object, the annual dynamic simulation model of the system is built through TSNSYS. The linear weighted evaluation function method is used for multi-objective optimization analysis of system performance and cost. The results show that the selection scheme with a PV area of 26 m2, a phase change volume of 0.14 m3, and a valley electricity storage ratio of 1 has the best-combined performance and cost of the system.

Abstract Pump-turbines (RPT) nowadays represents the most common mechanical equipment adopted in the new generation of storage hydro plant. In order to balance the frequent changes in electricity production and consumption caused by unpredictable renewable energy sources, RPT are forced to rapidly switch between the pumping and generating mode also extending their operation under off-design conditions in unstable operating areas. Because of the design criterion adopted for the development of a RPT, an unstable behavior represented by a typical S-shaped profile with a positive slope in the machine’s characteristic can occur near to the runaway condition. With the purpose of evaluating the evolution of the fluid field near to the no-load condition, an in-depth CFD analysis of the RPT model test of the Norwegian Hydropower Center is performed by retracing the machine’s characteristic curve running through the flow-speed characteristic curve up to the turbine brake region for fixed guide vanes opening. To validate the numerical results, a comparison with the experimental results in terms of characteristic curves and pressure signals is performed. The results allow to capture the 3D characteristics of the unsteady phenomena, progressively evolving in an organized rotating stall, highlighting also the influence of the flow rate change from partial loads to the turbine brake operation on their development. In order to characterize the pulsating nature of the instability phenomena developing in the runner and in the rotor-stator interaction, a time-frequency analysis is performed on the numeric pressure and torque signals. The combination between fluid-dynamic and time-frequency analysis makes it possible to identify and characterize three evolution phases: inception, growth and consolidation.

The unstable operation of a centrifugal pump under the gas-liquid two-phase condition seriously affects its performance and reliability. In order to study the gas phase distribution and the unsteady force in an impeller, based on the Euler-Euler heterogeneous flow model, the steady and unsteady numerical calculations of the gas-liquid two-phase full flow field in a centrifugal pump was carried out, and the simulation results were compared with the test data. The results show that the test results are in good agreement with the simulation data, which proves the accuracy of the numerical calculation method. The energy performance curve of the model pump decreases with the increase of the gas content, which illustrates a serious impact on the performance under the part-load operating condition. The results reveal that the high-efficiency-operating range become narrow, as the gas content increases. The gas phase is mainly distributed on the suction surface of the impeller blades. When the gas content reaches a certain value, the gas phase separation occurs. As the inlet gas content increases, the radial force on the impeller blades decreases. The pattern of the pressure pulsation is similar to that under pure water and low gas content conditions, and the number of peaks during the pulsation is equal to the number of the impeller blades. After the gas content reaches a certain value, the pressure fluctuates disorderly and the magnitude and the direction of radial force change frequently, which are detrimental to the operation stability of the pump. The intensity of the pressure pulsations in the impeller flow channel continues to increase in the direction of the flow under pure water conditions. The pressure pulsation intensities at the blade inlet and the volute tongue become more severe with the increase of the gas content.

<p class="03Abstract">Emulsions are thermodynamically unstable systems where droplet size is one of the main factors that affect its physical stability and consequently their quality. In this context, this work analyses the incorporation of a high shear homogenization step in the manufacturing process of an emulsion with the objective of maintaining its physical stability. In order to demonstrate the effects of this homogenization in the manufacturing process, the emulsion characterization was carried out by microscopy, rheology, laser diffraction and analytical photo-centrifugation techniques. The effect of high shear homogenization into the emulsion physical results was dependent on the speed applied to the homogenizer pump, with an effective 3600 rpm speed. There was no evidence of change on pH attributes and emulsion density, although there was a change in volumetric relationship between the droplet family presented in each sample, reducing the population of larger droplets to form a third family of intermediate droplets and increasing the volumetric proportion of the population of smaller droplets. This profile change in the droplet size distribution contributed to increased viscosity and emulsion without the presence of separation after it was submitted to the stress condition of temperature and agitation.</p>

After orange processing, different by-products are generated, i.e., peels, seeds and pulps. The pulp is highly perishable, being an unstable food matrix that needs a preservation process to be stored and used again in the food production chain. Pasteurization is the technique of choice before aseptically packaging and storing under refrigerated conditions. In this study, the effect of pasteurization has been evaluated on the chemical, functional and sensorial profiles. Ash content decreased (p < 0.05) after the thermal treatment. Indeed, magnesium, calcium and zinc diminished, although copper was found to be higher (p < 0.05) in the pasteurized product. Total dietary fiber decreased (p < 0.05), but soluble dietary fiber raised (p < 0.05) due to hydrolysis caused by pasteurization. SDF:IDF ratio, hydration properties, and fat binding capacity were improved. Total soluble phenolic compounds remained similar but FRAP and DPPH scavenging activity decreased (p < 0.05) in the pasteurized by-product. Regarding the sensorial profile, pasteurization produced darkening, appearance of a cooked smell and an increase in bitterness. Therefore, pasteurization deteriorates the sensorial profile being able to change the attributes of an added-pasteurized-pulp juice; however, it is a good choice to preserve the orange pulp by-product to formulate food products different from juices or other beverages.

A multi-region dynamic slip method was established to study the internal flow characteristics of the mixed-flow pump under the Alford effect. The ANSYS Fluent software and the standard k-ε two-equation model were used to numerically predict the mixed-flow pump’s external characteristics and analyze the forces on the impeller and guide vane internal vortex structure and non-uniform tip gap of the mixed-flow pump at different eccentric distances. The research results show that the external characteristic results of the numerical calculation are consistent with the experimental measurement. The head error of the design flow operating point is about 5%, and the efficiency error is no more than 3%, indicating the high accuracy of numerical calculation. Eccentricity has a significant influence on the flow field in the tip area of the mixed-flow pump impeller, the distribution of vortex core in the impeller presents obvious asymmetry, the strength and distribution area of the vortex core in the small gap area of the tip increase obviously, which aggravates the flow instability and increases the energy loss. With the increase of eccentricity, the strength and number of vortex core structures in the guide vane also increase significantly, and obvious flow separation occurs near the inlet of the guide vane suction surface on the eccentric side of the impeller. The circumferential distribution of L1 and L2 values represents the friction pressure gap in the eccentric state, and the eccentricity has a more noticeable effect on L1 and L2 values at the small gap; With the increase of eccentricity, the values of vorticity moment components L1 and L2 increase, and the Alford moment on the impeller increases. The leading-edge region of the blade is the main part affected by the unstable torque of the flow field. With the increase of eccentricity, the impact degree of tip leakage flow deepens, and the change of the tip surface pressure is the most obvious. The impact area of tip leakage flow is mainly concentrated in the first half of the impeller channel, which has an impact on the blade inlet flow field but has little impact on the blade outlet flow field.

ABSTRACT The stability of antipseudomonal β-lactams in concentrated solutions was examined in view of their potential administration by continuous infusion with external pumps (for intensive care patients) or with portable pumps carried under clothing (for cystic fibrosis patients). Aztreonam (100 g/liter), piperacillin (128 g/liter, with tazobactam), and azlocillin (128 g/liter) remained 90% stable for up to more than 24 h at 37°C (mezlocillin [128 g/liter] was stable at 25°C but not at 37°C). Ceftazidime (120 g/liter), cefpirome (32 g/liter), and cefepime (50 g/liter) remained 90% stable for up to 24, 23.7, and 20.5 h at 25°C but only for 8, 7.25, and 13 h at 37°C, respectively. The control of temperature therefore appears to be critical for all three cephalosporins that cannot be recommended for use in portable pumps carried under clothes for prolonged periods for reasons of stability. Cefpirome and cefepime solutions developed an important color change (from light yellow to dark red) upon exposure when stored at 30°C or higher. Degradation of ceftazidime was accompanied by the liberation of pyridine which, at 37°C, was in excess of what is allowed by the U.S. Pharmacopeia, i.e., 1.1 mg/liter, after 8 and 12 h for drug concentrations of 12 and 8.3%, respectively. Imipenem and meropenem are too unstable (10% degradation at 25°C after 3.5 and 5.15 h, respectively) to be recommended for use by continuous infusion. Faropenem, examined in comparison with imipenem and meropenem, proved as stable as aztreonam or piperacillin.

On account of its minimal expense and a high potential for change into energy-producing products, lignocellulosic biomass is the future of bioenergy and energy. Notwithstanding, their true capacity is restricted by the utilization of inefficient and unstable enzymes. Therefore, the present work aim to investigate the cellulose degradation potential of two isolated fungal species Aspergillus terreus and Trichoderma harzanium followed by bioethanol production from acid-thermal pre-treated rice straw (RS). The experiments were conducted in two phases. In phase-I of experiments, the isolated cellulose-degrading fungal species (Aspergillus terreus and Trichoderma harzanium) were employed for enzymatic hydrolysis of pretreated RS which was separated into two fractions namely: (Hydrolysate liquid) HL and (Residual pulp) RP. In phase-II of experiments, the enzymatically hydrolyzed substrate was subjected to yeast fermentation for bioethanol production. Using 18S rRNA sequencing, the microbial diversity study of the isolated species is covered in detail. The results revealed that the isolated fungal species A. terreus and T. harzanium resulted in 80 % of cellulose degradation. The highest bioethanol yield of 0.38 and 0.42 g/g of glucose was obtained from HL using Aspergillus terreus and Trichoderma harzanium treatment followed by yeast fermentation. The bioethanol yield of 0.17 g/g of cellulose was obtained from HL using both the fungal species.

Abstract Patient presentation. A fifty y/o male patient with a history of congenital aortic stenosis surgically corrected previously and with chronic heart failure due to severe left ventricular dysfunction presented to our emergency department complaining dyspnea. Due to acute decompensated heart failure with ongoing cardiogenic shock, he was admitted to our intensive cardiology unit. Initial work up. The blood exams showed a normal renal and liver function, normal total and free calcium, 9.4 mg/dL and 1.16 mmol/L respectively, lactates were mildly increased. The chest x–ray showed pulmonary congestion. At the echocardiography we found severe biventricular dysfunction, moderate mitral regurgitation, severe pulmonary hypertension. Since the patient was unstable, adrenaline, high–dose sodium nitroprusside (SNP), and intra–aortic balloon pump were started. The right heart catheterization revealed combined pulmonary hypertension reversible with SNP and, therefore, the patient was inserted in the heart transplant list. Diagnosis and Management. One of the side effects of SNP is the thiocyanate toxicity. A high dose of SNP was necessary for this patient (2.2 mcg/kg/min). Thus, thiocyanate levels increased up to 10 mg/100 mL (NV&lt;3). Importantly, the patient was asymptomatic despite these levels. However, the free calcium ion progressively decreased up to 0.94 mmol/L, despite normal total calcium and calcium supplementation iv and orally. Since arrhythmic burden markedly increased, we started lidocaine which was not effective. Follow–up. Since we suspected a possible causative role of thiocyanate, which might bond the double positive charged free calcium ion with its two negatively charged sulfur atoms, explaining the normal total calcium level and the low calcium ion, we carefully reduced SNP dose within days. This allowed us to reduce thiocyanate to 6 mg/100 mL, without compromising patient hemodynamics. Concomitantly, the free calcium ion tended to normalize, lowering the arrhythmic burden. Conclusions We describe for the first time a proarrhythmic side effect of prolonged SNP infusion, likely related to thiocyanate accumulation and free calcium ion binding, which, despite aggressive calcium supplementation, was normalized only after SNP down titration.

This trial had the objective of characterizing the microbial population and evaluating the aerobic stability of Marandu grass silages with pelleted citrus pulp (PCP). The collected forage was submitted to the following treatments: Silage of Marandu grass; silage of Marandu grass + 50 g/kg PCP and silage of Marandu grass + 100 g/kg PCP on natural matter basis. Metal cylindrical containers with 80 cm of height and 50 cm of diameter were used as silos during assays of microbiological dynamics and chemical changes of silages in anaerobiosis. Evaluations were performed on days 0, 2, 4 and 6 after silos were opened. The aerobic stability was evaluated by change in temperature, using approximately three kilograms of silage inside styrofoam boxes that were placed inside a climatic chamber. A completely randomized experimental design and split plot arrangement were used in the two assays, with five replications. Treatments were the plots and time was the subplots. Bacillus and enterobacteria were present on the Marandu grass silages with 0 g/kg PCP, which also showed pH increase throughout the feedout phase. Yeast was detected on the silages that were added with PCP. A trend of increasing temperature with extension of the aeration time was observed mainly in the silages containing 100 g/kg PCP. Isolated yeast strains showed lactate assimilation. Silages were found to be unstable due to the silo opening, both by bacterial or yeast development, which reduced the nutritional value.

One of the water quality parameters that are important to consider in fish farming is pH. Unstable pH conditions can cause a decrease in water quality and cause fish to harvest less than optimal yields. Under certain conditions, there is an extreme change in the pH value, so it needs to be normalized again. This study aims to design a monitoring and control system of pH for catfish farming. The control system consisted of an SKU SEN0161 type pH sensor, equipped with two pumps to automatically flow alkaline and acidic pH solutions. The design method used was the prototyping method, i.e. Listen to Customer (Design criteria collection), Design and Build Prototype, and Test Drive and Evaluation. Based on the static characteristic test on the pH sensor, it was found that the pH sensor reading error was 0.11 with a deviation of 0.03. A small error value indicates that the sensor has high accuracy and a little deviation value indicates that the sensor has a high level of precision. For the repeatability test with an interval measurement of 5 minutes, the sensor measurement had a deviation of 0.01. The performance test of the pH control system showed that the system had been able to control the pH according to the set point (6 and 7.5), both under acidic conditions (pH 5.4) and under alkaline conditions (pH 8). The system had also been able to store and display data on Android devices in real-time (24 hours non-stop) via an internet connection, making it easier to monitor by users. It was also found that catfish can grow well at pH 6.5-8.

Reversible pump-turbines are versatile in the electricity market since they can be switched between pump and turbine operation within a few minutes. The emphasis on the design of the more sensitive pump flow however often leads to stability problems in no load or turbine brake operation. Unstable characteristics can be responsible for hydraulic system oscillations in these operating points. The cause of the unstable characteristics can be found in the blocking effect of either stationary vortex formation or rotating stall. The so-called unstable characteristic in turbine brake operation is defined by the change of sign of the slope of the head curve. This change of sign or “S-shape” can be traced back to flow recirculation and vortex formation within the runner and the vaneless space between runner and guide vanes. When approaching part load from sound turbine flow the vortices initially develop and collapse again. This unsteady vortex formation induces periodical pressure fluctuations. In the turbine brake operation at small guide vane openings the vortices increase in intensity, stabilize and circumferentially block the flow passages. This stationary vortex formation is associated with a total pressure rise over the machine and leads to the slope change of the characteristic. Rotating stall is a flow instability which extends from the runner, the vaneless space to the guide and the stay vane channels at large guide vane openings. A certain number of channels is blocked (rotating stall cell) while the other channels comprise sound flow. Due to a momentum exchange between rotor and stator at the front and the rear cell boundary, the cell is rotating with subsynchronous frequency of about 60 percent of the rotational speed for the investigated pump-turbine (nq = 45). The enforced rotating pressure distributions in the vaneless space lead to large dynamic radial forces on the runner. The mechanisms leading to stationary vortex formation and rotating stall were analyzed with a pump-turbine model by the means of numerical simulations and test rig measurements. It was found that stationary vortex formation and rotating stall have initially the same physical cause, but it depends on the mean convective acceleration within the guide vane channels, whether the vortex formations will rotate or not. Both phenomena lead to an unstable characteristic.

Unstable flow within a reactor coolant pump (RCP)’s mechanical seal may cause the change of its sealing parameters, possibly threatening RCP’s safe operations. In this study, based on the moving grid technology, a 3D fluid–structure interaction analysis model is established, where the influence of parameters such as the inlet pressure fluctuation, closing force fluctuation, and speed fluctuation on mechanical seal performance characteristics within an RCP is numerically studied. Study results have shown that when pressure and closing force fluctuations are applied, the static ring displacement, the inlet-to-outlet temperature difference, and the leakage difference show similar variational rules. In addition, it is found that the sealing parameters are more sensitive to the step form of fluctuation. When the step change of 4% closing force was applied, the static ring displacement was more than 36.7%, the change of the temperature difference between inlet and outlet zones exceeded 53.5%, and the leakage difference was more than 127.2%. The change of speed has also been found to significantly affect the temperature difference between the RCP mechanical seal’s inlet and outlet, but the effect on the leakage and opening force was negligible.

To investigate the unsteady evolution characteristics and mechanism of cavitation at the tongue and its influence on the flow field in a centrifugal pump, numerical calculations were performed to research the occurrence and development of cavitation at the tongue under large flow rate conditions. The numerical calculation results were verified by experiments. The proper orthogonal decomposition (POD) method was used to decompose and reconstruct the flow field at the tongue of the centrifugal pump. The relationship between the typical frequency of pressure pulsation and the mainstream structure of the flow field was established. The POD method could accurately extract the coherent structure caused by cavitation and capture the unstable flow structure produced by vortex shedding. Under different available net positive suction head ( NPSHa) conditions, the 1st mode was the mainstream structural mode in the original flow field, with low-frequency and single-frequency components. The 2nd, 3rd and 4th modes were the main oscillation modes of the original flow field and showed the characteristics of high frequency and multiple frequencies. High-order modes could capture the complex flow field structure caused by the change in the large-scale vortex structure induced by the unsteady pulsation of cavitation.

Due to the temperature of shallow aquifers being affected by atmospheric temperature, groundwater source heat pumps (GWSHPs) become unstable and the operation efficiency of GWSHP is constrained. In the study, the coupling numerical simulation model of the groundwater flow field and temperature field is established based on the continuous monitoring results in an actual experimental site, and the water and thermal migration of shallow aquifer is simulated under the influence of the atmospheric environment. The influence of the dynamic change in ground temperature is analyzed on a GWSHP. The results indicated that the temperature of the shallow aquifer is affected by the external temperature, and the recharge temperature in the summer cooling period was 33°C, and that in the winter heating period was 6°C in the actual site, to avoid the occurrence of thermal penetration when there is a gap between the actual situation and the design situation, the single cooler can balance the insufficient cooling capacity in summer under the most unfavorable situation. The research results can also provide a reference for the development and utilization of geothermal energy resources in shallow aquifers.

Abstract In this work, the unsteady Reynolds-averaged Navier–Stokes (URANS) and three hybrid Reynolds-averaged Navier–Stokes-large eddy simulation (RANS-LES) models are employed to resolve the vortical flows in a typical single-stage side channel pump, to evaluate the suitability of these advanced turbulence models in predicting the pump hydraulic performance and unstable swirling flows. By the comparison of the overall performance, it can be observed that the results obtained by scale-adapted simulation (SAS) are closer to test data than shear stress transport (SST), detached eddy simulation (DES) and filter-based model (FBM). Simultaneously, the distribution of axial velocity on the plane near the interface is used to describe the position and intensity of internal fluid exchange between impeller and side channel. It is obvious that the intensity of mass flow exchange is strong near the inner and outer edges. Then, the vortex core region illustrates that the vortex is easily produced near the interface due to internal fluid exchange. Finally, the evolutions of circumferential in-plane vortical structures are presented to further account for the process of fluid exchange and the main vortex flows. It reveals that the recirculation flow presents a strong instability during 6–7 blade pitches as the fluid enters into the impeller and the flow is stable in downstream 7–8 blade pitches. Besides, the flow turns to be unsteady near outlet affected by the sudden change of fluid direction. This work could provide some suggestions for the choice of appropriate turbulence model in simulating strong swirling flows.

Research has been carried out that aims (i) to design a feeding system and water pH regulation in catfish farming automatically, (ii) to assemble and build a control circuit with existing electronic components and sensors, (iii) to apply the IoT system to pH controller made to be controlled remotely. The tool is designed to control the pH of the water by means of circulation and for measuring the pH of the water in the catfish pond, it is carried out periodically using a pH sensor of type PH4502C. The system uses the RTC DS1307 digital clock module to determine the feeding schedule. Smartphone communication with control circuits uses internet media for data transfer and commands. Regulates feeding in catfish ponds and integrates with smartphones. The design of the feeding system and pH regulation in catfish farming automatically, the tool can provide feed and regulate the pH of the water automatically according to a schedule that has been set with the program that has been made. The circuit is assembled and built into the chassis by installing all electronic components and sensors on the PCB. Such as the process of automation of feeding using a servo motor, to measure the pH of the water using a pH sensor and setting the pH of the water using a water pump. By using the RTC as a digital clock to provide time information on the microcontroller so that the program can run according to what has been made. The application of the IoT system to the pH controller and feeding device that is made is controlled remotely. This tool is able to send information and commands from two directions using an adapter device from Wifi, namely the MCU Node. The MCU node is set to be related to the Wifi hotspot and connectivity with the Blynk server on the smartphone. Menu settings are made according to the required display, namely the pH display, buttons to activate and deactivate the water pump, feeding, and notifications if there is a change in the pH of the water or if the pH of the water is unstable

Abstract Background CpxR is a critical regulator in bacterial adaptation to various harmful stresses, and is known to regulate bacterial resistance to commonly used antibiotics, such as aminoglycosides, β-lactams and polypeptides. However, the detailed study of functional residues of CpxR remains insufficient. Objectives To investigate the contribution of Lys219 to CpxR’s function in regulating antibiotic resistance of Escherichia coli. Methods We performed sequence alignment and conservative analysis of the CpxR protein and constructed mutant strains. We then performed electrophoretic mobility shift assay, real-time quantitative PCR assay, determination of reactive oxygen species (ROS) levels, molecular dynamics simulation, conformational analysis and circular dichroism. Results All mutant proteins (K219Q, K219A and K219R) lost the cpxP DNA-binding ability. Additionally, the three complemented strains eK219A, eK219Q, and eK219R exhibited lower resistance to copper toxicity and alkaline pH toxicity than eWT. Molecular dynamics analysis revealed that mutation of Lys219 leads to looser and more unstable conformation of CpxR, leading to its decreased binding affinity with downstream genes. Moreover, the Lys219 mutation resulted in the down-regulation of efflux pump genes (acrD, tolC, mdtB and mdtA), leading to the accumulation of antibiotics inside the cells and an increase in ROS production, which significantly reduces antibiotic resistance. Conclusions The mutation of the key residue Lys219 causes a conformational change that results in the loss of regulatory ability of CpxR, which may potentially reduce to antibiotic resistance. Therefore, this study suggests that targeting the highly conserved sequence of CpxR could be a promising strategy for the development of new antibacterial drugs.

Abstract The inducers increase the pressure available at the inlet of the impellers of centrifugal pumps. This technological solution may induce instabilities, such as prerotating flow at partial flow rates. The scientific literature offers studies on the cavitation in the inducers, as well as on the associated instabilities. However, studies describing devices that improve the behavior in these unstable regimes are rare. This is particularly true for fluids like aviation fuels or liquids with dissolved gases. In this work we expose, an experimental study for two axial inducers carried out at low flow rates in cavitating and noncavitating regimes in a closed-loop equipped with a transparent test pipe. The working liquid is water with and without dissolved CO2. We employ a camera and a high-speed camera to take the photographs of the dynamics of the cavitation structures. The experimental campaign provided results of head breakdown comparison. The added dissolved CO2 gas at a concentration of 300 mg L–1 does not change the overall inducers' performance in noncavitating regime. The paper presents also the impact of some of inducers' geometrical parameters on their cavitating performance. The authors observed prerotating flow instability, which they tried to decrease by incorporating a grooved ring into the inlet side of the inducers. It is found that prerotating structures are much less developed in the upstream when a grooved ring is employed.

Abstract This paper investigates the generation of the ultra-broadwidth (0.1-30 THz) terahertz (THz) radiation carrying fractional/integer orbital angular momentums (OAMs) via the interaction of the two-color (ω0 and 2ω0) laser field carrying initial fractional topological charges (TCs) with air in a moderate pump intensity regime (20 TW/cm2<Ipump<50 TW/cm2). The two four-wave mixing (FWM) processes (i.e., ω0+ω′0-2ω0→ωTHz and 2ω0-ω0-ω′0→ωTHz) are responsible for THz generation. The two processes can produce two THz pulses. They interfere with each other and THz interference vortex beams are obtained. More importantly, the generation probability from the first FWM process grows while that of the second process declines in the positive frequency region over distance. This is largely due to the combined action of phase mismatch and the blue shift of the THz center frequency. For a longer distance, THz fractional/integer vortex beams (FVBs/IVBs) are produced by the dominant FWM process (ω0+ω′0-2ω0→ωTHz). Therefore, via employing different combinations of the initial TCs of the ω0 and 2ω0 pulses, one can manipulate the generation of the THz vortex beams with arbitrary fractional-order or integer-order TCs at some specific propagation distances. What is even more interesting is that, when employing half-integer TCs, THz FVBs with varying TC over distance can be produced, companied with birth and annihilation of the alternative vortex pair. This is principally due to diffraction-related effects and the unstable nature of the fractional vortex structures. This simple manipulation for THz waves carrying arbitrary fractional or integer TCs in this scheme encourages the applications for optically rotation, manipulation of molecular or cell assays and image edge enhancement in the field of biomedicine.

Introduction: Cardiogenic shock occurs in 10% of patients with takotsubo cardiomyopathy (TTC) as a result of severe systolic dysfunction, or left ventricular outflow tract (LVOT) obstruction. Methods: Case report and review of the literature. Results: A 62-year-old female with a history of hypertension and diabetes mellitus presented with lightheadedness, shortness of breath, and chest discomfort. She was hemodynamically unstable, tachycardic, and hypotensive (70/40 mmHg). Her EKG showed sinus tachycardia at 101 BPM with 1 mm ST depression in leads II, III, AVF; V3-V6. Chest radiograph revealed pulmonary edema. High-sensitive troponin was 146.7. She was intubated for respiratory distress and had rapidly increasing vasopressor requirements. Emergent coronary angiography revealed nonobstructive coronary artery disease. A left ventriculogram revealed apical ballooning with an estimated ejection fraction of 25%, consistent with TTC. Transthoracic echocardiogram (TTE) showed severe mid and apical LV hypokinesis with basal hyperkinesis. Additionally, systolic anterior motion (SAM) of the mitral valve (MV) was noted, with a peak LVOT gradient of 7 mmHg. The patient improved clinically, and all support was weaned off. However, she later acutely developed recurrent respiratory distress and hypotension. Repeat TTE showed LVOT obstruction with a gradient of 40 mmHg due to increased basal hyperkinesis and SAM. The choice of vasopressor was switched from norepinephrine to phenylephrine to reduce the obstruction. She clinically improved and metoprolol succinate was added to reduce basal hypercontractility and improve left ventricular filling. Conclusions: Differentiating the mechanism of shock in TTC can easily be accomplished with TTE, and is essential to guiding treatment. The initial acute systolic dysfunction was effectively managed with norepinephrine, dopamine, and an intra-aortic balloon pump. She later developed LVOT obstruction as her systolic function improved. This was recognized with TTE and led to an appropriate change in vasopressor, as norepinephrine would have worsened the obstruction. This highlights the importance of early TTE in patients presenting with undifferentiated shock, especially when TTC is suspected.

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Inotropic support is frequently needed after acute coronary syndromes(ACS) at coronary care units(CCU). Despite it has being long time since approval of levosimendan(LV) as inotropic support to cardiogenic shock, dobutamine(DB) still being the basis of this treatment. We think levosimendan is a secure and effective alternative. Purpose To analyse the use of levosimendan and dobutamine done in our ACS patients to determine if we have followed some clear criteria of selection, and try to draw a defined pattern for future use. Method Retrospective, analytic, observational study of all ACS admitted to our CCU between 08/2011- 02/2022. We confront patients treated with dobutamine versus levosimendan. X2, U-Mann Whitney and T-Student were used when necessary. Statistical significance: p-value&lt;0.05. Result 2881patients were admitted with ACS, 6.49%of them(n: 187) needed ionotropic support. Out of these, 60.96%(n: 114) were supported with dobutamine, 28.88%(n: 54) with levosimedan and 10.16%(n: 19)received in some time both drugs, so were excluded from the analysis. Mean age: 68.43±11.48years old. 66.66%(n: 112) men. 54.76%(n: 92)with persistent ST-segment elevation. No difference was found between groups, neither in past medical history, including cardiovascular risk factors, history of arrhythmias(11.3% of patients), previous use of betablockers(30.4%), antiarrhythmic drugs(0.6%) or having pacemaker(1.2%). 114 patients(67.86%)needed norepinephrine(70.17%with DB and 62.96% LV, p:0.35); 29(17.26%) were supported with intra-aortic balloon pump(20.18% in DB group and 11.11% in LV group, p:0.134), without differences by drug. 62 patients(36.9%) presented atrial fibrillation(33.33% in DB and 44.44% in LV, p:0.166), 58(34.52%)ventricular arrhythmias[sustained ventricular tachycardia/ventricular fibrillation](33.33% in DB and 37.04% in LV, p:0.638). In-hospital mortality of these patients was 29.17%(n:49), 29.82% in DB and 27.77% in LV, p:0.785. In multivariate analysis adjusted by clinic and epidemiologic factors, only cardiogenic shock resulted an independent predictor of in-hospital death. Pattern of use we use DB in those patients with worst Killip-kimball(KK) state(73.54%in DB group with KK-IV vs53.70%in LV´s) and LV in those in intermediate states of instability(38.88%LV in KK-II/III vs 8.84%DB in KK-II/III),p&lt;0.001. We chose DB in those who became unstable in CCU and LV in those who became unstable in hospitalization room, p:0.049. Finally, we noted a significant change in trend of use during the period of study, falling use of DB in favour of LV(p&lt;0.001). Conclusion In our experience, dobutamine has been the most frequent ionotropic drug used in last 11 years after an acute coronary syndrome. Nevertheless, a substitution by levosimendan trend is evolving. We did not detect differences in complications or prognosis dependent on the inotropic drug used, but the use of dobutamine were predominant in those patients with more severe situation.

Abstract Measured results are presented for rotordynamic coefficients and mass leakage rates of a long smooth annular seal (length-to-diameter ratio L/D = 0.75, diameter D = 114.686 mm, and radial clearance Cr = 0.200 mm) tested with a mixture of silicone oil (PSF-5cSt) and air. The test seal is centered, the seal exit pressure is maintained at 6.9 bars-g while the fluid inlet temperature is controlled within 37.8–40.6 °C. It is tested with three inlet-preswirl inserts, namely, zero, medium, and high (the preswirl ratios (PSRs), i.e., the ratio between the fluid's circumferential velocity and the shaft surface's velocity, are in ranges of 0.10–0.18, 0.30–0.65, and 0.65–1.40 for zero, medium, and high preswirls, respectively), six inlet gas-volume fractions GVFi (0%, 2%, 4%, 6%, 8%, and 10%), four pressure drops PDs (20.7, 27.6, 34.5, and 41.4 bars), and three speeds ω (3, 4, and 5 krpm). The targeted test matrix could not be achieved for the medium- and high-preswirl inserts at PD ≥ 27.6 bars due to the test-rig stator's dynamic instability issues. Spargers were used to inject air into the oil, and GVFi values higher than 0.10 could not be consistently achieved because of unsteady surging flow downstream from the sparger mixing section. Leakage mass flow rate m˙ and rotordynamic coefficients are measured, and the effect of changing inlet preswirl and GVFi is studied. The test results are then compared with predictions from a two-phase, homogeneous-mixture, bulk-flow model developed in 2011. Generally, both measurements and predictions show little change in m˙ as inlet preswirl changes. Measured m˙ remains unchanged or slightly increases with increasing GVFi, but predicted m˙ decreases. Measured m˙ is comparable to predicted values but consistently lower. Dynamic-stiffness coefficients are measured using an ensemble of excitation frequencies and curve-fitted well by frequency-independent stiffness Kij, damping Cij, and virtual mass Mij coefficients. Planned tests with the medium- and high-preswirl inserts could not be accomplished at PD = 34.5 and 41.4 bars because the seal stator became unstable with any finite injection of air. The test results show that the instability arose because the seal's direct stiffness K became negative and increased in magnitude with increasing GVFi. The model predicts a drop in K as GVFi increases, but the test results dropped substantially more rapidly than predicted. Also, the model does not predict the observed strong tendency for K to drop with an increase in preswirl in moving from the zero-to-medium and medium-to-high preswirl inserts. The authors believe that the observed drop in K due to increasing GVFi is not explained by either (a) a reverse Lomakin effect from operating in the transition flow regime or (b) the predicted drop in K at higher GVFi values from the model. A separate and as yet unidentified two-phase flow phenomenon probably causes the observed results. The negative K results due to increasing GVFi and moving from the zero to medium, and medium to high preswirl observed here could explain the instability issue (sudden subsynchronous vibration) on a high-differential-pressure helico-axial multiphase pump (MPP), reported in 2013. Effective damping Ceff combines the stabilizing effect of direct damping C, the destabilizing effect of cross-coupled stiffness k, and the influence of cross-coupled mass mq. As predicted and measured, increasing inlet preswirl significantly increases k and decreases Ceff, which decreases the seal's stabilizing properties. Ceff increases with increasing GVFi—becomes more stable.

In his directorial debut, The Man with the Iron Fists (2012), RZA not only evokes the textual borrowing techniques he has utilised as a hip-hop producer, but also reflects the influence of filmmaker Quentin Tarantino, who has built a career upon acknowledging mainstream and cult film histories through mise-en-scene, editing, and deft characterisation. The Man with the Iron Fists was originally to coincide with Tarantino’s rebel slave narrative Django Unchained (2012), which Tarantino has discussed openly as commentary regarding race in contemporary America. In 2011, Variety reported that RZA had joined the cast of Tarantino’s anticipated Django Unchained, playing “Thaddeus, a violent slave working on a Mississippi plantation” (Sneider, “Rza Joins ‘Django Unchained’ Cast”). Django Unchained follows Tarantino’s pattern of generic and trope mixology, combining elements of the Western, blaxploitation, and buddy/road film. He famously stated: “[If] my work has anything it's that I'm taking this from this and that from that and mixing them together… I steal from everything. Great artists steal; they don't do homages” (“The Directors of Our Lifetime: In Their Own Words”). He sutures iconography from multiple films in numerous genres to form new texts that stand alone, albeit as amalgamations of references. In considering meanings attached particularly to exploitation films, this article addresses the significance of combining influences within The Man with the Iron Fists and Tarantino’s Django Unchained, and the ideological threads that emerge in fusing exploitation film aesthetics. Ultimately, these films provide a convergence not only of texts, but also of the collective identities associated with and built upon those texts, feats made possible through the filmmakers’ use of pastiche. Pastiche in Identity Formation as Subversive A reflection of the postmodern tendency towards appropriation and borrowing, pastiche is often considered less meaningful than its counterpart, parody. Fredric Jameson suggests that though pastiche and parody share commonalities (most notably the mimicry of style and mannerisms), they do so to different effects. Jameson asserts that parody mimics in an effort to mock the idiosyncrasies within a text, whereas pastiche is “neutral parody” of “dead styles” (114). In short, as Susan Hayward writes, “In its uninventiveness, pastiche is but a shadow of its former thing” (302). For Jameson, the most ubiquitous form of pastiche is the nostalgia film, which attempts to recapture the essence of the past. As examples, he points to the George Lucas films American Graffiti (1973), which is staged in the United States of the 1950s, and Star Wars (1977), which reflects the serials of the 1930s-1950s (114-115). Though scholars such as Jameson and Hayward are contemptuous of pastiche, a growing number see its potential for the subversion and critique that the aforementioned suggest it lacks. For instance, Sarah Smith reminds us that pastiche films engage in “complicitous critique”: the films maintain the trappings of original texts, yet do so in order to advance critique (209). For Smith and other scholars, such as Judith Butler and Richard Dyer, Jameson’s criticism of pastiche is dismissive, for while these scholars largely agree that pastiche is a form of mimicry in which the distance between original and copy is minimal, they recognise that a space still exists for it to be critical. Smith writes: “[W]hile there may be greater distance between the parody and its target text than there is between the pastiche and the text it imitates, a prescribed degree of distance is not a prerequisite for critical engagement with the ur-text” (210). In this regard, fidelity to the original texts is not only required but to be revered, for these likenesses to the original “act as a guarantee of the critique of those origins and provide an opportunity for the filmmaker to position [himself or herself] in relation to them” (Smith 211). Essentially, pastiche is a useful technique in which to construct hybrid identities. Keri E. Iyall Smith suggests that hybrid identities emerge from “a reflexive relationship between local and global” (3). According to popular music scholar Brett Lashua, hybrid identities “make and re-make culture through appropriating the cultural ‘raw materials’ of life in order to construct meaning in their own specific cultural localities. In a sense, they are ‘sampling’ from broader popular culture and reworking what they can take into their own specific local cultures” (“The Arts of the Remix: Ethnography and Rap”). As will be evidenced here, Tarantino utilises pastiche as an unabashed genre poacher; similarly, as a self-avowed Tarantino student and hip-hop producer known for his sampling acumen, RZA invokes pastiche to reflect mastery of his craft and a hybridised identity his multifaceted persona. Plagiarism, Poaching, and Pastiche: Tarantino Blurs Boundaries As a filmmaker, Tarantino is known for indulging in excess: violence, language, and aesthetics. Edward Gallafent characterised the director’s work as having a preoccupation with settings and journeys, violence (both emotional and physical), complicated chronological structures, and dissatisfying conclusions (3-4). Additionally, pieces of Tarantino’s cinematic fandom are inserted into his own films. Academic and popular critics continually note Tarantino’s rise as an obsessive video store clerk turned respected and eccentric auteur. Tarantino’s authorship lies mostly in his ability to borrow (or in his words, steal) narrative arcs, characterisations, and camera work from other filmmakers, and use them in ways that feel innovative and different from those past works. It is not that he borrows generally from movements, films, and filmmakers, but that he conscientiously lifts segments from works to incorporate into his text. In Postmodern Hollywood: What’s New in Film and Why It Makes Us Feel So Strange, Keith M. Booker contends that Tarantino’s work often straddles lines between simplistic reference for reference’s sake and meditations upon the roles of cinema (90). Booker dismisses claims for the latter, citing Tarantino’s unwillingness to contextualise the references in Pulp Fiction, such that the film is best described not an act of citation so much as a break with the historical. Tarantino’s lack of reverence provides him freedom to intermingle texts and tropes to fit his goals as a filmmaker, rather than working within the confines of generic narratives. Each film feels both apart and distinct from genre categories. Jackie Brown, for example, has many of the traits attached to blaxploitation, from its focus on drug culture, the casting of Pam Grier who gained status playing female leads in blaxploitation films, and extreme violence. Tarantino’s use of humour throughout, particular in his treatment of character types, plot twists, and self-aware musical cues distances the film from easy characterisation. It is, but isn’t. What is gained is a remediated conception of cinematic reality. The fictions created in films of the past are noted in Tarantino’s play with tropes. His mixes produce an extreme form of mediated reality – one that is full of excess, highly exaggerated, and completely composed of stolen frameworks. Tarantino continues his generic play in Django Unchained. While much of it does borrow heavily from 1960s and 1970s Western filmmakers like Leone, Corbucci, and Peckinpah (the significance of desolate landscapes, long takes, extreme violence), it also incorporates strands of buddy cop (partners with different backgrounds working together to correct wrongs), early blaxploitation (Broomhilda’s last name is von Shaft suggesting that she is an ancestor of blaxploitation icon John Shaft, the characterisation of Django as black antihero enacting revenge on white racists in power), and kung fu (revenge narrative, in addition to the extensive training moments between Dr. Schultz and Django). The familiar elements highlight the transgressions of genre adherence. The comfort of the western genre and its tropes eases the audience, only for Tarantino to incorporate those elements from outside the genre to spark interest, to shock, to remind audiences of the mediated reality onscreen. Tarantino has been criticised for his lack of depth and understanding regarding women and people of colour, despite his attempts to provide various leading and supporting roles for both. Django Unchained was particularly criticised for Tarantino’s use of the term nigger - over 100 instances in the film. Tarantino defended his decision by claiming historical accuracy, poetic license, and his desire to confront audiences with various levels of racism. Many, including Spike Lee, disagreed, arguing Tarantino had no claim to making a film about slavery. Lee stated through Twitter: “American Slavery Was Not A Sergio Leone Spaghetti Western. It Was A Holocaust. My Ancestors Are Slaves. Stolen From Africa. I Will Honor Them” (“Spike Lee on Django Unchained: Filmmaker Calls Movie ‘Disrespectful’”). Not only does Lee evoke the tragedy of the American slave trade and the significance of race within contemporary filmmaking, but he uses genre to underscore what he perceives is Tarantino’s lack of reverence to the issue of slavery and its aftermath in American culture. Django Unchained is both physically and emotionally brutal. The world created by Tarantino is culturally messy, as Italian composers rub elbows with black hip-hop artists, actors from films’ referenced in Django Unchained interact with new types of heroes. The amounts of references, people, and spectacles in his films have created a brand that is both hyperaware, but often critiqued as ambivalent. This is due in part to the perception of Tarantino as a filmmaker with no filter. His brand as a filmmaker is action ordered, excessive, and injected with his own fandom. He is an ultimate poacher of texts and it is this aesthetic, which has also made him a fan favourite amongst young cinephiles. Not only does he embrace the amount of play film offers, but he takes the familiar and makes it strange. The worlds he creates are hazier, darker, and unstable. Creating such a world in Django Unchained provides a lot of potential for reading race in film and American culture. He and his defenders have discussed this film as an “honest” portrayal of the effects of slavery and racial tension in the United States. This is also the world which acts as context for RZA’s The Man with the Iron Fists. Though a reference abandoned in Django Unchained, the connection between both films and both filmmakers pleasure in pastiche provide further insight to connections between film and race. Doing the Knowledge: RZA Pays Homage As a filmmaker, RZA utilises Tarantino’s filmmaking brand techniques to build his own homage and add to the body of kung-fu films. Doing so furnishes him the opportunity to rehash and reform narratives and tropes in ways that change familiar narrative structures and plot devices. In creating a film which relies on cinematic allusions to kung fu, RZA—as a fan, practitioner, and author—reconfigures kung fu from being an exploitative genre and reshapes its potential for representational empowerment. While Tarantino considers himself an unabashed thief of genre tropes, RZA envisions himself more as a student who pays homage to masters—among whom he includes Tarantino. Indeed, in an interview with MTV, RZA refers to Tarantino as his Sifu (a Chinese term for master or teacher) and credits him not only for teaching RZA about filmmaking, but also for providing him with his blessing to make his first feature length film (Downey, “RZA Recalls Learning from ‘The Master’ Quentin Tarantino”). RZA implies that mastery of one’s craft comes from incorporating influences while creating original work, not theft. For instance, he states that the Pink Blossom brothel—the locus for most of the action in the film—was inspired by the House of Blue Leaves restaurant, which functions in a similar capacity in Tarantino’s Kill Bill: Vol. 1 (“RZA Talks Sampling of Kung Fu Films for Movie & The Difference Between Biting vs. Influence”). Hip-hop is an art form in which its practitioners “partake of a discursive universe where skill at appropriating the fragments of a rapidly-changing world with verbal grace and dexterity is constituted as knowledge” (Potter 21). This knowledge draws upon not only the contemporary moment but also the larger body of recorded music and sound, both of which it “re-reads and Signifies upon through a complex set of strategies, including samplin’, cuttin’ (pastiche), and freestylin’ (improvisation)” (Potter 22). As an artist who came of age in hip-hop’s formative years and whose formal recording career began at the latter half of hip-hop’s Golden Age (often considered 1986-1993), RZA is a particularly adept cutter and sampler – indeed, as a sampler, RZA is often considered a master. While RZA’s samples run the gamut of the musical spectrum, he is especially known for sampling obscure, often indeterminable jazz and soul tracks. Imani Perry suggests that this measure of fidelity to the past is borne out of hip-hop’s ideological respect for ancestors and its inherent sense of nostalgia (54). Hallmarks of RZA’s sampling repertoire include dialog and sound effects from equally obscure kung fu films. RZA attributes his sampling of kung fu to an affinity for these films established in his youth after viewing noteworthy examples such as The 36th Chamber of Shaolin (1978) and Five Deadly Venoms (1978). These films have become a key aspect of his identity and everyday life (Gross, “RZA’s Edge: The RZA’s Guide to Kung Fu Films”). He speaks of his decision to make kung fu dialog an integral part of Wu-Tang Clan’s first album Enter the Wu-Tang (36 Chambers): “My fantasy was to make a one-hour movie that people were just going to listen to. They would hear my movie and see it in their minds. I’d read comic books like that, with sonic effects and kung fu voices in my head. That makes it more exciting so I try to create music in the same way” (Gross, ““RZA’s Edge: The RZA’s Guide to Kung Fu Films”). Much like Enter the Wu-Tang (36 Chambers) and his other musical endeavours, The Man with the Iron Fists serves as further evidence of RZA’s hybrid identity., which sociologist Keri E. Iyall Smith suggests emerges from “a reflexive relationship between local and global” (3). According to popular music scholar Brett Lashua, hybrid identities “make and re-make culture through appropriating the cultural ‘raw materials’ of life in order to construct meaning in their own specific cultural localities. In a sense, they are ‘sampling’ from broader popular culture and reworking what they can take into their own specific local cultures” (“The Arts of the Remix: Ethnography and Rap”). The most overt instance of RZA’s hybridity is in regards to names, many of which are derived from the Gordon Liu film Shaolin and Wu-Tang (1983), in which the competing martial arts schools come together to fight a common foe. The film is the basis not only for the name of RZA’s group (Wu-Tang Clan) but also for the names of individual members (for instance, Master Killer—after the series to which the film belongs) and the group’s home base of Staten Island, New York, which they frequently refer to as “Shaolin.” The Man with the Iron Fists is another extension of this hybrid identity. Kung fu has long had meaning for African Americans particularly because these films frequently “focus narratively on either the triumph of the ‘little guy’ or ‘underdog’ or the nobility of the struggle to recognise humanity and virtue in all people, or some combination of both” (Ongiri 35). As evidence, Amy Obugo Ongiri points to films such as The 36th Chamber of Shaolin, a film about a peasant who learns martial arts at the Shaolin temple in order to avenge his family’s murder by the Manchu rulers (Ongiri 35). RZA reifies this notion in a GQ interview, where he speaks about The 36th Chamber of Shaolin specifically, noting its theme of rebellion against government oppression having relevance to his life as an African American (Pappademus, “This Movie Is Rated Wu”). RZA appropriates the humble origins of the peasant San Te (Gordon Liu), the protagonist of The 36th Chamber of Shaolin, in Thaddeus (whom RZA plays in the film), whose journey to saviour of Jungle Village begins with his being a slave in America. Indeed, one might argue that RZA’s construction of and role as Thaddeus is the ultimate realisation of the hybrid identity he has developed since becoming a popular recording artist. Just as Tarantino’s acting in his own films often reflects his identity as genre splicer and convention breaker (particularly since they are often self-referential), RZA’s portrayal of Thaddeus—as an African American, as a martial artist, and as a “conscious” human being—reflects the narrative RZA has constructed about his own life. Conclusion The same amount of play Tarantino has with conventions, particularly in characterisations and notions of heroism, is present in RZA’s Man with the Iron Fists. Both filmmakers poach from their favourite films and genres in order to create interpretations that feel both familiar and new. RZA follows Tarantino’s aesthetic of borrowing scenes directly from other films. Both filmmakers poach from films for their own devices, but in those mash-ups open up avenues for genre critique and identity formation. Tarantino is right to say that they are not solely homages, as homages honour the films in which they borrow. Tarantino and RZA do more through their poaching to stretch the boundaries of genres and films’ abilities to communicate with audiences. References “The Directors of Our Lifetime: In Their Own Words.” Empire Online. N.d. 8 May 2013 ‹http://www.empireonline.com/magazine/250/directors-of-our-lifetime/5.asp›. Booker, Keith M. Postmodern Hollywood: What’s New in Film and Why It Makes Us Feel So Strange. Westport, CT: Praeger, 2007. 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Snedier, Jeff. “Rza Joins 'Django Unchained' Cast.” Variety 2 Nov. 2011. 14 June 2013 ‹http://variety.com/2011/film/news/rza-joins-django-unchained-cast-1118045503/›. “Spike Lee on Django Unchained: Filmmaker Calls Movie ‘Disrespectful.’” Huffington Post 24 Dec. 2012. 14 June 2013 ‹http://www.huffingtonpost.com/2012/12/23/spike-lee-django-unchained-movie-disrespectful_n_2356729.html›. Wu-Tang Clan. Enter the Wu-Tang (36 Chambers). Loud, 1993. Filmography The 36th Chamber of Shaolin. Dir. Chia-Liang Lui. Perf. Chia Hui Lui, Lieh Lo, Chia Yung Lui. Shaw Brothers, 1978. Django Unchained. Dir. Quentin Tarantino. Perf. Jamie Foxx, Leonardo DiCaprio, Christoph Waltz. Miramax, 2012. Five Deadly Venoms. Dir. Cheh Chang. Perf. Sheng Chiang, Philip Kwok, Feng Lu. Shaw Brothers, 1978. Jackie Brown. Dir. Quentin Tarantino. Perf. Pam Grier, Samuel L. Jackson, Robert Forster. Miramax, 1997. Kill Bill: Vol. 1. Dir. Quentin Tarantino. Perf. Uma Thurman, David Carradine, Darryl Hannah. Miramax, 2003. The Man with the Iron Fists. Dir. RZA. Perf. RZA, Russell Crowe, Lucy Liu. Arcade Pictures, 2012. Pulp Fiction. Dir. Quentin Tarantino. Perf. John Travolta, Uma Thurman, Samuel L. Jackson. Miramax, 1994. Shaolin and Wu-Tang. Dir. Chiu Hui Liu. Perf. Chiu Hui Liu, Adam Cheng, Li Ching.