41 research outputs found
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Development of a Model for Performance Analysis of a Honeycomb Thermal Energy Storage for Solar Power Microturbine Applications
Solar power microturbines are required to produce steady power despite the fluctuating solar radiation, with concerns on the dispatchability of such plants where thermal energy storage may offer a solution to address the issue. This paper presents a mathematical model for performance prediction of a honeycomb sensible-heat thermal energy storage designed for application of concentrated solar power microturbine. The focus in the model is to consider the laminar developing boundary layers at the entry of the flow channels, which could have a profound effect on the heat-transfer coefficient due to large velocity and temperature gradients, an effect which has not been considered in the modelling of such storage systems. Analysing the thermal and hydrodynamic boundary layer development, the Nusselt number and the friction factor were evaluated using a validated conjugate heat-transfer method. The simulations results were used to develop accurate regression functions for Nusselt number and friction factor. These formulations have been adopted within a one-dimensional model to evaluate the performance of the storage under different operating conditions. The model was in good agreement with conjugate heat transfer results with maximum relative error below 2%. Two case studies are presented to demonstrate the applicability of the proposed methodology
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Thermodynamic modelling and real-time control strategies of solar micro gas turbine system with thermochemical energy storage
Distributed solar gas turbine systems with thermal energy storage are expected to overcome the intermittence and instability of solar irradiance and produce reliable and flexible electricity for remote districts and islands. Here, a mathematical model is developed for a 10 kWe solar micro gas turbine (MGT) system with thermochemical energy storage (TCES) to study the system thermodynamic characteristics at real-world direct normal irradiation (DNI) variations. Real-time control strategies aiming for stable operation and set point tracing are proposed and implemented in transient simulations to analyze the control effect against both short- and long-term DNI disturbances based on system dynamics. Results show that, by regulating the output power, rotational speed (N) is kept constant, and system responses are smoothened (e.g., less than 5.8% fluctuation of the mass flow rate). Power regulation also enables a constant turbine outlet temperature (TOT) and the optimal overall performance (e.g., output power and total efficiency exceeding 14 kWe and 14%, respectively). By combining power and bypass regulations, N and TOT can simultaneously remain constant while outputting a stable power of 12.6 kWe ±5% under 750–820 W/m2, with a sharp drop to 500 W/m2. For favorable weather, N-TOT simultaneous control can guarantee the high and stable system performance. If massive clouds appear, constant TOT operation is more advantageous during peak load demand for larger electricity generation, while constant N operation is preferable during low power demand for smoother turbine operation.
Furthermore, the addition of TCES smoothens the performance variation and prolongs the generation duration. TCES also allows constant TOT operation to store up to 32% more energy than constant N and output 18–28 kWh more energy during daytime operation, thanks to the higher operating temperature. Overall, the proposed real-time control methods reduce the dependency on fossil fuel combustion and contribute to the stable, safe, and efficient operation of a distributed high-percentage-solar-share MGT system.(1) National Natural Science Foundation of China (NO. 51776186), (2) Foundation for Innovative Research Groups of the National Natural Science Foundation of China (NO. 51621005) and (3) National Natural Science Foundation of China (NO. 51906214)
Early Cretaceous continental arc magmatism in the Wakhan Corridor, South Pamir: mantle evolution and geodynamic processes during flat subduction of the Neo-Tethys oceanic slab
Subduction polarity reversal facilitated by plate coupling during arc-continent collision: Evidence from the Western Kunlun orogenic belt, NW China
Exploring the effects of lysozyme dietary supplementation on laying hens: performance, egg quality, and immune response
An experiment was conducted to evaluate the dietary supplementation with lysozyme's impacts on laying performance, egg quality, biochemical analysis, body immunity, and intestinal morphology. A total of 720 Jingfen No. 1 laying hens (53 weeks old) were randomly assigned into five groups, with six replicates in each group and 24 hens per replicate. The basal diet was administered to the laying hens in the control group, and it was supplemented with 100, 200, 300, or 400 mg/kg of lysozyme (purity of 10% and an enzyme activity of 3,110 U/mg) for other groups. The preliminary observation of the laying rate lasted for 4 weeks, and the experimental period lasted for 8 weeks. The findings demonstrated that lysozyme might enhance production performance by lowering the rate of sand-shelled eggs (P < 0.05), particularly 200 and 300 mg/kg compared with the control group. Lysozyme did not show any negative effect on egg quality or the health of laying hens (P > 0.05). Lysozyme administration in the diet could improve intestinal morphology, immune efficiency, and nutritional digestibility in laying hens when compared with the control group (P < 0.05). These observations showed that lysozyme is safe to use as a feed supplement for the production of laying hens. Dietary supplementation with 200 to 300 mg/kg lysozyme should be suggested to farmers as a proper level of feed additive in laying hens breeding
ACORN (A Clinically-Oriented Antimicrobial Resistance Surveillance Network) II: protocol for case based antimicrobial resistance surveillance
Background: Antimicrobial resistance surveillance is essential for empiric antibiotic prescribing, infection prevention and control policies and to drive novel antibiotic discovery. However, most existing surveillance systems are isolate-based without supporting patient-based clinical data, and not widely implemented especially in low- and middle-income countries (LMICs). Methods: A Clinically-Oriented Antimicrobial Resistance Surveillance Network (ACORN) II is a large-scale multicentre protocol which builds on the WHO Global Antimicrobial Resistance and Use Surveillance System to estimate syndromic and pathogen outcomes along with associated health economic costs. ACORN-healthcare associated infection (ACORN-HAI) is an extension study which focuses on healthcare-associated bloodstream infections and ventilator-associated pneumonia. Our main aim is to implement an efficient clinically-oriented antimicrobial resistance surveillance system, which can be incorporated as part of routine workflow in hospitals in LMICs. These surveillance systems include hospitalised patients of any age with clinically compatible acute community-acquired or healthcare-associated bacterial infection syndromes, and who were prescribed parenteral antibiotics. Diagnostic stewardship activities will be implemented to optimise microbiology culture specimen collection practices. Basic patient characteristics, clinician diagnosis, empiric treatment, infection severity and risk factors for HAI are recorded on enrolment and during 28-day follow-up. An R Shiny application can be used offline and online for merging clinical and microbiology data, and generating collated reports to inform local antibiotic stewardship and infection control policies. Discussion: ACORN II is a comprehensive antimicrobial resistance surveillance activity which advocates pragmatic implementation and prioritises improving local diagnostic and antibiotic prescribing practices through patient-centred data collection. These data can be rapidly communicated to local physicians and infection prevention and control teams. Relative ease of data collection promotes sustainability and maximises participation and scalability. With ACORN-HAI as an example, ACORN II has the capacity to accommodate extensions to investigate further specific questions of interest
Supplemental Material: Subduction polarity reversal facilitated by plate coupling during arc-continent collision: Evidence from the Western Kunlun orogenic belt, northwest Tibetan Plateau
Materials and methods, Figures S1–S6, and Tables S1–S7.  </p
Imaging and measuring the molecular force of lymphoma pathological cells using atomic force microscopy
Summary Atomic force microscopy (AFM) provides a new technology to visualize the cellular topography and quantify the molecular interactions at nanometer spatial resolution. In this work, AFM was used to image the cellular topography and measure the molecular force of pathological cells from B-cell lymphoma patients. After the fluorescence staining, cancer cells were recognized by their special morphological features and then the detailed topography was visualized by AFM imaging. The AFM images showed that cancer cells were much rougher than healthy cells. CD20 is a surface marker of B cells and rituximab is a monoclonal antibody against CD20. To measure the CD20-rituximab interaction forces, the polyethylene glycol (PEG) linker was used to link rituximab onto the AFM tip and the verification experiments of the functionalized probe indicated that rituximab molecules were successfully linked onto the AFM tip. The CD20-rituximab interaction forces were measured on about 20 pathological cells and the force measurement results indicated the CD20-rituximab binding forces were mainly in the range of 110-120 pN and 130-140 pN. These results can improve our understanding of the topography and molecular force of lymphoma pathological cells. SCANNING 35:40-46, 2013. © 2012 Wiley Periodicals, Inc. © Wiley Periodicals, Inc.Link_to_subscribed_fulltex
Nanoscale mapping and organization analysis of target proteins on cancer cells from B-cell lymphoma patients
CD20, a membrane protein highly expressed on most B-cell lymphomas, is an effective target demonstrated in clinical practice for treating B-cell non-Hodgkin's lymphoma (NHL). Rituximab is a monoclonal antibody against CD20. In this work, we applied atomic force microscopy (AFM) to map the nanoscale distribution of CD20 molecules on the surface of cancer cells from clinical B-cell NHL patients under the assistance of ROR1 fluorescence recognition (ROR1 is a specific cell surface marker exclusively expressed on cancer cells). First, the ROR1 fluorescence labeling experiments showed that ROR1 was expressed on cancer cells from B-cell lymphoma patients, but not on normal cells from healthy volunteers. Next, under the guidance of ROR1 fluorescence, the rituximab-conjugated AFM tips were moved to cancer cells to image the cellular morphologies and detect the CD20-rituximab interactions on the cell surfaces. The distribution maps of CD20 on cancer cells were constructed by obtaining arrays of (16×16) force curves in local areas (500×500nm2) on the cell surfaces. The experimental results provide a new approach to directly investigate the nanoscale distribution of target protein on single clinical cancer cells. © 2013 Elsevier Inc.Link_to_subscribed_fulltex
Investigating the relationship between CD20-Rituximab binding force and mechanical properties of Lymphom B cells using atomic force microscopy
The invention of atomic force microscopy (AFM) provides new technology for investigating the physiological activities at the single cell and single molecule levels. Lymphoma Raji cells were adsorbed onto the glass slides by coating the glass slides with poly-L-lysine. Rituximabs (anti-CD20 antibody) were linked onto the AFM tip by PEG linker and the CD20-Rituximab binding forces were measured on three lymphoma Raji cells. Then the mechanical properties of the Raji cells were dynamically measured after the Rituximab activation by obtaining force curves on the cell surface. The mechanical properties of lymphoma cells kept stable at the first 20-30 min, and then decreased markedly. Besides, as the CD20-Rituximab binding force increased, the mechanical properties decrease rate increased. The experimental results indicated that the Rituximab's effect is related to CD20-Rituximab binding force and can improve our understanding of Rituximab's variable efficacies in different patients. © 2012 IEEE.Link_to_subscribed_fulltex