| 1. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 2. |
- Bentham, James, et al.
(författare)
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A century of trends in adult human height
- 2016
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Ingår i: eLIFE. - 2050-084X. ; 5
-
Tidskriftsartikel (refereegranskat)abstract
- Being taller is associated with enhanced longevity, and higher education and earnings. We reanalysed 1472 population-based studies, with measurement of height on more than 18.6 million participants to estimate mean height for people born between 1896 and 1996 in 200 countries. The largest gain in adult height over the past century has occurred in South Korean women and Iranian men, who became 20.2 cm (95% credible interval 17.522.7) and 16.5 cm (13.319.7) taller, respectively. In contrast, there was little change in adult height in some sub-Saharan African countries and in South Asia over the century of analysis. The tallest people over these 100 years are men born in the Netherlands in the last quarter of 20th century, whose average heights surpassed 182.5 cm, and the shortest were women born in Guatemala in 1896 (140.3 cm; 135.8144.8). The height differential between the tallest and shortest populations was 19-20 cm a century ago, and has remained the same for women and increased for men a century later despite substantial changes in the ranking of countries.
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| 3. |
- Bentham, James, et al.
(författare)
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A century of trends in adult human height
- 2016
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Ingår i: eLIFE. - : eLife Sciences Publications Ltd. - 2050-084X. ; 5
-
Tidskriftsartikel (refereegranskat)abstract
- Being taller is associated with enhanced longevity, and higher education and earnings. We reanalysed 1472 population-based studies, with measurement of height on more than 18.6 million participants to estimate mean height for people born between 1896 and 1996 in 200 countries. The largest gain in adult height over the past century has occurred in South Korean women and Iranian men, who became 20.2 cm (95% credible interval 17.5–22.7) and 16.5 cm (13.3– 19.7) taller, respectively. In contrast, there was little change in adult height in some sub-Saharan African countries and in South Asia over the century of analysis. The tallest people over these 100 years are men born in the Netherlands in the last quarter of 20th century, whose average heights surpassed 182.5 cm, and the shortest were women born in Guatemala in 1896 (140.3 cm; 135.8– 144.8). The height differential between the tallest and shortest populations was 19-20 cm a century ago, and has remained the same for women and increased for men a century later despite substantial changes in the ranking of countries.
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| 4. |
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| 5. |
- Jin, Ying-Hui, et al.
(författare)
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Chemoprophylaxis, diagnosis, treatments, and discharge management of COVID-19 : An evidence-based clinical practice guideline (updated version)
- 2020
-
Ingår i: Military Medical Research. - : Springer Science and Business Media LLC. - 2054-9369. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of a rapidly spreading illness, coronavirus disease 2019 (COVID-19), affecting more than seventeen million people around the world. Diagnosis and treatment guidelines for clinicians caring for patients are needed. In the early stage, we have issued "A rapid advice guideline for the diagnosis and treatment of 2019 novel coronavirus (2019-nCoV) infected pneumonia (standard version)"; now there are many direct evidences emerged and may change some of previous recommendations and it is ripe for develop an evidence-based guideline. We formed a working group of clinical experts and methodologists. The steering group members proposed 29 questions that are relevant to the management of COVID-19 covering the following areas: chemoprophylaxis, diagnosis, treatments, and discharge management. We searched the literature for direct evidence on the management of COVID-19, and assessed its certainty generated recommendations using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach. Recommendations were either strong or weak, or in the form of ungraded consensus-based statement. Finally, we issued 34 statements. Among them, 6 were strong recommendations for, 14 were weak recommendations for, 3 were weak recommendations against and 11 were ungraded consensus-based statement. They covered topics of chemoprophylaxis (including agents and Traditional Chinese Medicine (TCM) agents), diagnosis (including clinical manifestations, reverse transcription-polymerase chain reaction (RT-PCR), respiratory tract specimens, IgM and IgG antibody tests, chest computed tomography, chest x-ray, and CT features of asymptomatic infections), treatments (including lopinavir-ritonavir, umifenovir, favipiravir, interferon, remdesivir, combination of antiviral drugs, hydroxychloroquine/chloroquine, interleukin-6 inhibitors, interleukin-1 inhibitors, glucocorticoid, qingfei paidu decoction, lianhua qingwen granules/capsules, convalescent plasma, lung transplantation, invasive or noninvasive ventilation, and extracorporeal membrane oxygenation (ECMO)), and discharge management (including discharge criteria and management plan in patients whose RT-PCR retesting shows SARS-CoV-2 positive after discharge). We also created two figures of these recommendations for the implementation purpose. We hope these recommendations can help support healthcare workers caring for COVID-19 patients.
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| 6. |
- Pecunia, Vincenzo, et al.
(författare)
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Roadmap on energy harvesting materials
- 2023
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Ingår i: Journal of Physics. - : IOP Publishing. - 2515-7639. ; 6:4
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Tidskriftsartikel (refereegranskat)abstract
- Ambient energy harvesting has great potential to contribute to sustainable development and address growing environmental challenges. Converting waste energy from energy-intensive processes and systems (e.g. combustion engines and furnaces) is crucial to reducing their environmental impact and achieving net-zero emissions. Compact energy harvesters will also be key to powering the exponentially growing smart devices ecosystem that is part of the Internet of Things, thus enabling futuristic applications that can improve our quality of life (e.g. smart homes, smart cities, smart manufacturing, and smart healthcare). To achieve these goals, innovative materials are needed to efficiently convert ambient energy into electricity through various physical mechanisms, such as the photovoltaic effect, thermoelectricity, piezoelectricity, triboelectricity, and radiofrequency wireless power transfer. By bringing together the perspectives of experts in various types of energy harvesting materials, this Roadmap provides extensive insights into recent advances and present challenges in the field. Additionally, the Roadmap analyses the key performance metrics of these technologies in relation to their ultimate energy conversion limits. Building on these insights, the Roadmap outlines promising directions for future research to fully harness the potential of energy harvesting materials for green energy anytime, anywhere.
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| 7. |
- Xun, Qian, 1990, et al.
(författare)
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Drive Cycle Energy Efficiency of Fuel Cell/Supercapacitor Passive Hybrid Vehicle System
- 2021
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Ingår i: IEEE Transactions on Industry Applications. - 0093-9994 .- 1939-9367. ; 57:1, s. 894-903
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Tidskriftsartikel (refereegranskat)abstract
- The electric vehicle with passive hybridization of fuel cells and supercapacitors leads to lower cost and compactness due to the absence of DC/DC converters. This paper models such a vehicle and evaluates the energy efficiency of its powertrain system. The powertrain component losses, as functions of electric machine torque, speed and DC-link voltage, are modelled with a high level of detail which are verified against available test data. Compared to a pure fuel cell system, the fuel cell efficiency is higher when supercapacitors are introduced under pulse current load, and it is higher at lower current amplitude. As the pulse current frequency increases, the fuel cell efficiency also increases due to higher proportional current from the high-efficiency supercapacitors. A multiplicity of drive cycles is selected, divided into a low, middle, and high speed category to analyze the powertrain efficiency. The total powertrain energy efficiency varies between 53%-71% during propulsion for the studied drive cycles, whereas it is higher during braking ranging from 84% to 94%. The differences are closely related to the speed, acceleration, and DC-link voltage levels. The lower powertrain efficiency causes higher hydrogen consumption, leading to a reduced fuel cell efficiency at high speed, high acceleration and low DC-link voltage.
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| 8. |
- Chen, Ying, et al.
(författare)
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Measurements of elastic modulus and fracture toughness of an air plasma sprayed thermal barrier coating using micro-cantilever bending
- 2019
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Ingår i: Surface & Coatings Technology. - : Elsevier BV. - 0257-8972 .- 1879-3347. ; 374, s. 12-20
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Tidskriftsartikel (refereegranskat)abstract
- The elastic modulus and fracture toughness of an air plasma sprayed thermal barrier coating (APS TBC) were measured using the micro-cantilever bending technique. The micro-cantilevers were machined by a focused ion beam with their central arms either parallel or normal to the bond coat/topcoat interface. Such orientations allowed direct measurements of both the in-plane and out-of-plane elastic moduli as well as mode I fracture toughness by bending. The calculated elastic modulus along the in-plane and out-of-plane direction is 144 GPa and 110 GPa, respectively, suggesting that the APS TBC is elastically anisotropic at microscale. The derived mode I fracture toughness along the plane parallel to the interface is 0.40 MPam. This relatively low toughness reflects the weak fracture resistance of the highly-flawed APS for short cracks at microscale. The measurements in this study can be incorporated into micromechanical life time prediction models of the APS TBCs. © 2019 Elsevier B.V.
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| 9. |
- Cosmas, John, et al.
(författare)
-
Towards joint communication and sensing (Chapter 4)
- 2023
-
Ingår i: Towards Sustainable and Trustworthy 6G: Challenges, Enablers, and Architectural Design. - 9781638282396 ; , s. 121-158
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Localization of user equipment (UE) in mobile communication networks has been supported from the early stages of 3rd generation partnership project (3GPP). With 5th Generation (5G) and its target use cases, localization is increasingly gaining importance. Integrated sensing and localization in 6th Generation (6G) networks promise the introduction of more efficient networks and compelling applications to be developed.
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| 10. |
- Fan, Wei, et al.
(författare)
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A Data-Driven Machining Error Analysis Method for Finish Machining of Assembly Interfaces of Large-Scale Components
- 2021
-
Ingår i: Journal of manufacturing science and engineering. - : ASME International. - 1087-1357 .- 1528-8935. ; 143:4
-
Tidskriftsartikel (refereegranskat)abstract
- To guarantee the final assembly quality of the large-scale components, the assembly interfaces of large components need to be finish-machined on site. Such assembly interfaces are often in low-stiffness structure and made of difficult-to-cut materials, which makes it hard to fulfill machining tolerance. To solve this issue, a data-driven adaptive machining error analysis and compensation method is proposed based on on-machine measurement. Within this context, an initial definite plane is fitted via an improved robust iterating least-squares plane-fitting method based on the spatial statistical analysis result of machining errors of the key measurement points. Then, the parameters of the definite plane are solved by a simulated annealing-particle swarm optimization (SA-PSO) algorithm to determine the optimal definite plane; it effectively decomposes the machining error into systematic error and process error. To reduce these errors, compensation methods, tool-path adjustment method, and an optimized group of cutting parameters are proposed. The proposed method is validated by a set of cutting tests of an assembly interface of a large-scale aircraft vertical tail. The results indicate that the machining errors are successfully separated, and each type of error has been reduced by the proposed method. A 0.017 mm machining accuracy of the wall-thickness of the assembly interface has been achieved, well fulfilling the requirement of 0.05 mm tolerance.
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| 11. |
- Hardwick, Martin, et al.
(författare)
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A roadmap for STEP-NC-enabled interoperable manufacturing
- 2013
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Ingår i: The International Journal of Advanced Manufacturing Technology. - : Springer Science and Business Media LLC. - 0268-3768 .- 1433-3015. ; 68:5-8, s. 1023-1037
-
Tidskriftsartikel (refereegranskat)abstract
- The STEP-NC-AP 238 and ISO 14649 standard is the result of a 10-year international effort to replace the RS274D (ISO 6983) G and M code standard with a modern associative language that connects the CAD design data used to determine the machining requirements for an operation with the CAM process data that is used in creating a machining solution to satisfy these requirements. STEP-NC builds on the previous 10 years effort to develop the STEP neutral data standard for CAD data, and uses the modern geometric constructs in that standard to specify device independent tool paths, and CAM independent volume removal features. STEP-Manufacturing, Team 24 in Working Group 3 (WG3) of ISO TC184/SC4, is developing and validating the STEP-NC standard in liaison with Working Group (WG7) of ISO TC184/SC1 who provides the domain-specific input (ISO 14649) used within the standard. This paper reviews the demonstrations carried out by STEP-Manufacturing over the past 10 years. These demonstrations have been international collaborations between industry, academia, and research agencies. Each demonstration focused on extending the STEP-NC data model for a different application.
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| 12. |
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| 13. |
- Petropoulos, Fotios, et al.
(författare)
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Operational Research : methods and applications
- 2024
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Ingår i: Journal of the Operational Research Society. - : Taylor & Francis Group. - 0160-5682 .- 1476-9360. ; 75:3, s. 423-617
-
Forskningsöversikt (refereegranskat)abstract
- Throughout its history, Operational Research has evolved to include methods, models and algorithms that have been applied to a wide range of contexts. This encyclopedic article consists of two main sections: methods and applications. The first summarises the up-to-date knowledge and provides an overview of the state-of-the-art methods and key developments in the various subdomains of the field. The second offers a wide-ranging list of areas where Operational Research has been applied. The article is meant to be read in a nonlinear fashion and used as a point of reference by a diverse pool of readers: academics, researchers, students, and practitioners. The entries within the methods and applications sections are presented in alphabetical order. The authors dedicate this paper to the 2023 Turkey/Syria earthquake victims. We sincerely hope that advances in OR will play a role towards minimising the pain and suffering caused by this and future catastrophes.
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| 14. |
- Sun, Xun, et al.
(författare)
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Large recoverable strain with suitable transition temperature in TiNb-based multicomponent shape memory alloys : First-principles calculations
- 2021
-
Ingår i: Acta Materialia. - : Elsevier BV. - 1359-6454 .- 1873-2453. ; 221
-
Tidskriftsartikel (refereegranskat)abstract
- TiNb-based shape memory alloys (SMAs) have great potentials in biomaterials. However, high transition temperature or small recoverable strain limit their application. Using first-principles method, we systematically study the recoverable strain and transition temperature of TiNb-based binary, ternary, and high-entropy alloys (HEAs), and aim to lower the transition temperature and improve the recoverable strain at the same time. We find that the employed approach describes accurately the lattice strain by comparing with the available experimental results. It is well known that there is a positive correlation between lattice strain and recoverable strain in SMAs. Thus, we have evaluated the magnitude of recoverable strain of SMAs by calculating the lattice strain. Meanwhile, we correlate the available measured martensitic transformation start temperature (M-s) with the calculated energy difference between beta and alpha'' phases in Ti-Nb binary alloys. According to this relation, we evaluate the M-s in other TiNb-based alloys. We find that Zr is a good alloying element that can decrease considerably the M-s and keep the lattice (recoverable) strain almost unchanged simultaneously. Finally, an Al-containing Ti24Nb25Zr24S24Al3 HEA has been designed to have simultaneously large recoverable strain and low transition temperature.
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| 15. |
- Sun, Xin, et al.
(författare)
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Reducing supply risk of critical materials for clean energy via foreign direct investment
- 2024
-
Ingår i: Nature Sustainability. - : Springer Nature. - 2398-9629. ; 7:5, s. 672-681
-
Tidskriftsartikel (refereegranskat)abstract
- Existing research on the security of the supply of critical materials for clean energy generally aggregates information at the country level, a practice that obscures the extensive role of foreign direct investment (FDI) in the production of critical materials. FDI refers to an ownership stake in a company or project by an overseas investor. Here we establish a database for global mining of lithium, cobalt, nickel and platinum at company level, covering 240 countries and regions. We show that 47% of lithium, 71% of cobalt, 41% of nickel and 34% of platinum mined in 2019 were under FDI. We then explore how FDI may affect supply risks by proposing a supply risk index that allocates production of the critical materials to the country of origin of investors instead of the country where production is located. We present upper and lower bounds of the supply risk index that reflect scenarios where either all investors or only state investors prioritize the home-country demand, respectively. This study presents an approach for assessing the national supply risks of critical materials, considering the geographical allocation of FDI.
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| 16. |
- Svanberg, Sune, et al.
(författare)
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Laser spectroscopy applied to environmental, ecological, agricultural and food safety research
- 2017
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Ingår i: International Conference on Photonics and Imaging in Biology and Medicine, PIBM 2017. - 9781557528209 ; Part F70-PIBM 2017
-
Konferensbidrag (refereegranskat)abstract
- Laser spectroscopy has a multitude of applications of importance to human and ecosystem well-being, such as in the environmental, ecological, agricultural and food safety areas. Recent work, mostly from SCNU, will be reviewed.
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| 17. |
- Wang, Fei, et al.
(författare)
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Endothelial cell heterogeneity and microglia regulons revealed by a pig cell landscape at single-cell level
- 2022
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Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 13:1
-
Tidskriftsartikel (refereegranskat)abstract
- Pigs are valuable large animal models for biomedical and genetic research, but insights into the tissue- and cell-type-specific transcriptome and heterogeneity remain limited. By leveraging single-cell RNA sequencing, we generate a multiple-organ single-cell transcriptomic map containing over 200,000 pig cells from 20 tissues/organs. We comprehensively characterize the heterogeneity of cells in tissues and identify 234 cell clusters, representing 58 major cell types. In-depth integrative analysis of endothelial cells reveals a high degree of heterogeneity. We identify several functionally distinct endothelial cell phenotypes, including an endothelial to mesenchymal transition subtype in adipose tissues. Intercellular communication analysis predicts tissue- and cell type-specific crosstalk between endothelial cells and other cell types through the VEGF, PDGF, TGF-beta, and BMP pathways. Regulon analysis of single-cell transcriptome of microglia in pig and 12 other species further identifies MEF2C as an evolutionally conserved regulon in the microglia. Our work describes the landscape of single-cell transcriptomes within diverse pig organs and identifies the heterogeneity of endothelial cells and evolutionally conserved regulon in microglia.
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| 18. |
- Wang, Jinlei, et al.
(författare)
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Development of wireless specific mosquito counter by optical technology
- 2018
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Ingår i: 2018 Asia Communications and Photonics Conference, ACP 2018. - 9781538661581 ; 2018-October
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Konferensbidrag (refereegranskat)abstract
- Mosquitoes carry malaria and dengue fever and constitute a great threat to public health. We develop a wireless mosquito counting device which can provide valuable statistic information.
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| 19. |
- Wang, Xun, et al.
(författare)
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Drone-based area scanning of vegetation fluorescence height profiles using a miniaturized hyperspectral lidar system
- 2018
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Ingår i: Applied Physics B: Lasers and Optics. - : Springer Science and Business Media LLC. - 0946-2171. ; 124:11
-
Tidskriftsartikel (refereegranskat)abstract
- We have developed a compact hyperspectral lidar system based on a continuous-wave (CW) 445 nm diode laser and a double Scheimpflug imaging arrangement. The light-weight construction allows the integration of the system on a commercial drone. Airborne, range-resolved spatial imaging of vegetation fluorescence is demonstrated.
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| 20. |
- Xun, Qian, 1990, et al.
(författare)
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Energy Efficiency Comparison of Hybrid Powertrain Systems for Fuel-Cell-Based Electric Vehicles
- 2020
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Ingår i: ITEC 2019 - 2019 IEEE Transportation Electrification Conference and Expo.
-
Konferensbidrag (refereegranskat)abstract
- Fuel cell electric vehicles have great superiorities in endurance mileage, charging speed and climate tolerance compared to battery electric vehicles. However, a supercapacitor or battery bank is required to maintain a fast-dynamic response, which leads to several hybridization structures for fuel-cell-based electric vehicles due to the unique characteristics of each device, and their performances are also differing. The purpose of this paper is to provide a comprehensive comparison of hybrid powertrain systems for three types of powertrains: fuel cell/supercapacitor passive hybrid, fuel cell/supercapacitor semi-active hybrid, and fuel cell/battery semi-active hybrid. Each powertrain component model is developed from the real components wherever possible, and Honda FCX Clarity fuel cell vehicle is studied as the benchmark. The powertrain energy efficiency under Worldwide harmonized Light vehicles Test Cycle (WLTC) is analyzed and evaluated. The simulation results show that three powertrains have the same energy consumption, and fuel cell/supercapacitor passive hybrid powertrain increases the system efficiency by 2% and 4% in propulsion and regenerative braking, respectively. By contrast, the other two powertrain topologies have similar performance in terms of energy efficiency.
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| 21. |
- Xun, Qian, 1990, et al.
(författare)
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Modelling and simulation of fuel cell/ supercapacitor passive hybrid vehicle system
- 2019
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Ingår i: 2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019. ; , s. 2690-2696
-
Konferensbidrag (refereegranskat)abstract
- The concept of the passive hybrid system is to develop a single-stage power conversion topology in which fuel cell and supercapacitor can be directly coupled, leading to low cost and compactness in the absence of DC/DC converters. The paper deals with the modelling and simulation of such a vehicle system. The powertrain component losses are modelled with a high level of detail, and they are functions of speed, torque and DC-link voltage. Different drive cycles divided into a low, middle, and high-speed category are used to evaluate the performance of the powertrain system. The wheel energy per distance and powertrain efficiency differs between the drive cycles due to the different speed and acceleration levels. Furthermore, the acceleration and WLTC characteristics of the powertrain system show that in the passive hybrid system, the supercapacitors can support fuel cells as a low-pass filter. As a result, the peak power requirement can be successfully achieved due to the lowered system impedance, and the fuel cell only needs to supply the average power during operation. © 2019 IEEE.
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| 22. |
- Zhao, Xue, et al.
(författare)
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Copper confined in vesicle-like BCN cavities promotes electrochemical reduction of nitrate to ammonia in water
- 2021
-
Ingår i: Journal of Materials Chemistry A. - : ROYAL SOC CHEMISTRY. - 2050-7488 .- 2050-7496. ; 9:41, s. 23675-23686
-
Tidskriftsartikel (refereegranskat)abstract
- Electrochemical methods to convert high-concentration nitrates present in sewage into high-value-added ammonia do not just alleviate the problem of environmental pollution but also provide less energy-intensive alternatives to the Haber-Bosch process. In this work, a metal-boron organic polymer precursor was annealed at high temperature to obtain copper nanoparticles encapsulated in a vesicle-like BCN matrix (BCN@Cu). In the electrochemical reduction of nitrate (E-NIRR), this species exhibited excellent catalytic activity. Specifically, the ammonia yields of BCN@Cu under applied potentials of -0.3 V, -0.4 V, -0.5 V, and -0.6 V versus the reversible hydrogen electrode were 271.1 mu mol h(-1) mg(cat.)(-1), 354.8 mu mol h(-1) mg(cat.)(-1), 435.6 mu mol h(-1) mg(cat.)(-1), and 576.2 mu mol h(-1) mg(cat.)(-1), respectively, and the corresponding Faraday efficiencies were 86.3%, 88.0%, 89.3%, and 88.9%. Isotope labeling experiments with (NO3-)-N-15 confirmed that the detected ammonia had originated from the electrochemical reduction of NO3- on the catalyst surface. Moreover, the E-NIRR activity of BCN@Cu remained high even after using it ten consecutive times or 20 h of continuous operation, suggesting the practicality of the industrial application of BCN@Cu. The presence of copper was key in determining BCN@Cus E-NIRR activity, while the presence of boron greatly improved its catalytic performance. Furthermore, density functional theory calculations indicated that BCN does not itself promote the reaction but rather assists the dispersion of Cu nanoparticles, thereby expanding the catalysts active surface area.
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| 23. |
- Zhao, Xue, et al.
(författare)
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Simultaneous anchoring of Ni nanoparticles and single-atom Ni on BCN matrix promotes efficient conversion of nitrate in water into high-value-added ammonia
- 2022
-
Ingår i: Chemical Engineering Journal. - : Elsevier. - 1385-8947 .- 1873-3212. ; 433:Part 2
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Tidskriftsartikel (refereegranskat)abstract
- Electrochemical synthesis of ammonia driven by clean energy is expected to realize the supply of ammonia for distributed production of industry and agriculture. Here, nickel nanoparticles and nickel in the form of single atoms were simultaneously anchored on the electrochemically active carrier BCN matrix through a structured domain strategy, which realized a high-efficiency, high-value-added, conversion of nitrate in sewage. Specifically, the electrochemical nitrate reduction reaction (NIRR) driven by BCN@Ni in alkaline media achieves an ammonia yield rate as high as 2320.2 μg h−1 cm−2 (at −0.5 V vs RHE), and Faraday efficiency as high as 91.15% (at −0.3 V vs RHE). Even in neutral and acidic media, the ammonia yield rates of NIRR driven by BCN@Ni are as high as 1904.2 μg h−1 cm−2 and 2057.4 μg h−1 cm−2, respectively (at −0.4 V vs RHE). The 15NO3- isotope labeling experiment verified that the recorded ammonia all came from the electrochemical reduction of NO3– on BCN@Ni. Density functional theory (DFT) calculations show that both nano-Ni and single-atom Ni in BCN@Ni have the ability to electrochemically convert NO3– into NH3, and that the addition of BCN can further promote the NIRR on Ni.
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| 24. |
- Zhao, Xue, et al.
(författare)
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Two-dimensional BCN matrix inlaid with single-atom-Cu driven electrochemical nitrate reduction reaction to achieve sustainable industrial-grade production of ammonia
- 2021
-
Ingår i: APPLIED MATERIALS TODAY. - : Elsevier. - 2352-9407. ; 25
-
Tidskriftsartikel (refereegranskat)abstract
- Electrochemical methods have been proven to effectively eliminate nitrates in sewage and convert them into high value-added ammonia products. Here, after annealing treatment of metal boron cluster organic polymers formed by the combination of 1,10-phenanthroline, Cu2+ and closo-[B12H12](2)(-), a Cu single-atom doped BCN (B-doped CN) with a diamond-shaped nanosheet structure was obtained. In the electrochem-ical reduction reaction of nitrate, BCN-Cu exhibits excellent catalytic activity, specifically: 1) the ammonia yield rate reached as high as 498.85 mu g h(-1) cm(-2), 1047.14 mu g h(-1) cm(-2), 1900.07 mu g h(-1) cm(-2) and 3358.74 mu g h(-1) cm(-2) at -0.3 V, -0.4 V, -0.5 V and -0.6 V vs reversible hydrogen electrode, respectively, and Faradaic efficiency is 95.90%, 97.28%, 98.23% and 97.37%; 2) after repeated use of BCN-Cu 10 times or continuous operation for 16 h, the activity against electrochemical reduction reaction of nitrate anions is almost unchanged. The (NO3-)-N-15 isotopic labeling experiment proved that the detected NH3 comes from the reduction of NO3- on BCN-Cu. Control experiments show that the presence of Cu determines whether BCN-Cu has the possibility of catalyzing electrochemical reduction reactions of nitrate, and the presence of the B element enhances the catalytic activity of BCN-Cu. Density functional calculations indicate that in the water phase the process of reducing NO3- to NH3 on Cu-0 is an exothermic reaction, and that the adsorption process of NO3- on Cu-0 is the rate-determining step.
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| 25. |
- Zhao, Zhiqi, et al.
(författare)
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Analysis of enhanced turbulent heat transfer in a sharp turn channel having novel designed endwall with longitudinal vortex generator
- 2022
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Ingår i: International Communications in Heat and Mass Transfer. - : Elsevier BV. - 0735-1933. ; 131
-
Tidskriftsartikel (refereegranskat)abstract
- This work provides a new method to enhance endwall heat transfer of a sharp turn channel. Several longitudinal vortex generators (LVGs) at various spacing and aspect ratio are placed in parallel on the inner side of endwall in a sharp turn channel. Liquid crystal thermography, pressure difference measurements, and a statistical method are applied to analyze the thermal behavior, friction factor, and temperature uniformity on the endwall mounted with an array of LVGs. The Reynolds number are in the range of 10,000 to 20,000. A comparison between the novel designed endwall and conventional turbulators in the same U bend channel is also conducted. Results indicate that the local Nusselt number is greatly augmented with the application of LVGs on the endwall, especially at the downstream part of the endwall. The LVGs with an aspect ratio of 2 and a spacing of 20 mm (dense case) provides the optimal thermal characteristics. The optimal design provides augmentation of heat transfer rate and thermal performance factor by up to 35.1% and 25.5%, respectively. The endwall fitted with delta-winglet vortex generators is a promising enhanced heat transfer method compared with the conventional design available for the same U-duct model.
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| 26. |
- Zhao, Zhiqi, et al.
(författare)
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Experimental evaluation of longitudinal and transverse vortex generators on the endwall of a serpentine passage
- 2022
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Ingår i: International Journal of Thermal Sciences. - : Elsevier BV. - 1290-0729. ; 176
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Tidskriftsartikel (refereegranskat)abstract
- A 180-deg turning channel can be seen in many heat exchange systems, and a strong three-dimensional flow phenomenon will occur at the turning point. In order to strengthen the heat transfer inside the turn and considering the lack of relevant enhanced endwall heat transfer approach, the present study innovatively demonstrates the measures of enhanced internal endwall heat transfer using arrays of delta-winglet and conical vortex generators. The studied parameters of the vortex generators include aspect ratio (AR), spacing, and angle of attack, etc. The experimental results indicate that the longitudinal vortex generators have more advantages in increasing the heat transfer than the transverse conical vortex generators in certain configurations with the same order of magnitude of the increased area. Besides, transverse conical vortex generators are more helpful to improve the endwall heat transfer uniformity than longitudinal vortex generators. The array of longitudinal vortex generators with 45-deg angle of attack, 0.02 m pitch, and 2 aspect ratio provides the highest thermal performance for all studied cases, indicating that the longitudinal delta-winglet vortex generators can induce near-wall flow turbulence as well as convective heat transfer of the endwall with a modest pressure loss penalty. For this optimally designed endwall, the Nusselt number is augmented by up to 35%. From the perspective of energy saving, the present studied vortex generators provide a superior thermal performance at identical pumping power, which can be useful in the future design of endwalls in sharp-turn channels.
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| 27. |
- Zhao, Zhiqi, et al.
(författare)
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Experimental study on the augmented Nusselt number of the endwall through a square-sectioned sharp-turn channel using novel heat exchanger
- 2022
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Ingår i: International Journal of Heat and Mass Transfer. - : Elsevier BV. - 0017-9310. ; 192
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Tidskriftsartikel (refereegranskat)abstract
- Aquiring higher thermal efficiency with minimum energy consumption is the continuous pursuit of heat exchanger design. This work aims to demonstrate a novel enhanced heat exchange approach for a two-pass heat exchanger surface using four forms of a novel heat exchanger (nHEX), such as high straight and low curved turbulators, etc. The nHEXs are arranged parallel and equally spaced on the internal endwall. A comparison between current design and conventionally turbulated endwalls of sharp-turn channels is presented. The results indicate that the heat transfer rate is greatly augmented by inserting an array of nHEXs compared to a smooth endwall channel. The strategically placed vortex generators can improve the lowest heat transfer region on the smooth endwall to achieve overall thermal enhancement and temperature uniformity. Among the studied geometries, higher height or straight forms of the nHEXs are prone to enhance endwall heat transfer. The high straight forms of the nHEXs provide the maximum improvement of the normalized Nusselt number and thermal enhancement factor in a sharp-turn channel, which are 32% and 18% higher than the corresponding values of the smooth endwall, respectively. This study proved the potential of an array of parallel nHEXs to provide endwall heat transfer enhancement in a sharp-turn channel with an acceptable pressure drop penalty.
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| 28. |
- Zhao, Zhiqi, et al.
(författare)
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The augmentation of internal tip heat transfer in gas turbine blades using a pair of delta-winglet vortex generators
- 2021
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Ingår i: Journal of Enhanced Heat Transfer. - 1065-5131. ; 28:3, s. 17-40
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Tidskriftsartikel (refereegranskat)abstract
- A novel method to enhance the heat transfer on the internal tip surface of gas turbine blades was developed. Effects of delta-winglet vortex generators (DWVG) and their angle of attack on the vortical structures and mechanism of enhanced heat transfer were investigated. Seven different angles of attack were considered: 0°, 15°, 30°, 45°, 60°, 75°, and 90°. The Reynolds number varies from 10,000 to 50,000. Flow topology analysis was employed to better understand the evolution of vortices in the turn region. Results showed that a vortex was induced on the leeward side of the DWVG as the angle of attack was greater than 0°, which significantly enhanced the local heat transfer. Also, an extra saddle point was generated at the tip surface on the windward side of the DWVG as the angle of attack is greater than 45°, indicating that a vortex wass formed. The internal tip heat transfer increased as the angle of attack of the DWVG increased. The optimal design was reached when the angle of attack is greater than 60°. Compared with the smooth channel, the heat transfer and overall thermal performance are enhanced by up to 9.5% and 8.1%, respectively.
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| 29. |
- Zhong, Yi, et al.
(författare)
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Orbital Controls on North Pacific Dust Flux During the Late Quaternary
- 2024
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Ingår i: Geophysical Research Letters. - 0094-8276. ; 51:4
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Tidskriftsartikel (refereegranskat)abstract
- Airborne mineral dust is sensitive to climatic changes, but its response to orbital forcing is still not fully understood. Here, we present a reconstruction of dust input to the Subarctic Pacific Ocean covering the past 190 kyr. The dust composition record is indicative of source moisture conditions, which were dominated by precessional variations. In contrast, the dust flux record is dominated by obliquity variations and displays an out-of-phase relationship with a dust record from the mid-latitude North Pacific Ocean. Climate model simulations suggest precession likely drove changes in the aridity and extent of dust source regions. Additionally, the obliquity variations in dust flux can be explained by meridional shifts in the North Pacific westerly jet, driven by changes in the meridional atmospheric temperature gradient. Overall, our findings suggest that North Pacific dust input was primarily modulated by orbital-controlled source aridity and the strength and position of the westerly winds.
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| 30. |
- Zhong, Yi, et al.
(författare)
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Paleoclimate evolution of the North Pacific Ocean during the late Quaternary : Progress and challenges
- 2023
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Ingår i: Geosystems and Geoenvironment. - : Elsevier BV. - 2772-8838. ; 2:1
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Forskningsöversikt (refereegranskat)abstract
- High- and low-latitude climatic processes in the North Pacific Ocean are important components of the global climate system. For example, the interplay among North Pacific atmospheric circulation, ocean circulation, and biological productivity affects atmospheric carbon dioxide levels and marine oxygen concentrations. Here we review recent research on the North Pacific paleoclimatic and paleoceanographic evolution during the late Quaternary and its response to external forcings such as orbital insolation, ice-sheet extent, and greenhouse gas concentrations. First, we summarize the principles and application of relative paleointensity as a critical chronological tool in North Pacific paleoclimate research. Second, we illustrate the latest discoveries on the interaction between North Pacific Intermediate Water formation and high-to-low latitude teleconnection processes. Third, recent progress in linking dust fluxes and marine productivity and their global significance for the carbon cycle are presented. Finally, several key scientific problems are highlighted for future research on ocean-atmosphere-climate interactions in the North Pacific, pointing to the importance of combining paleo-records and modeling simulations. Overall, this review also aims to provide a broad insight into possible future changes of ocean-atmosphere circulation in the North Pacific region under a rapidly warming climate.
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