The mismatch between the photovoltaic(PV)cells absorption and the solar irradiance on earth is one of the major limitations towards more efficient PV energy conversion.This aspect was addressed by downshifting the sol...The mismatch between the photovoltaic(PV)cells absorption and the solar irradiance on earth is one of the major limitations towards more efficient PV energy conversion.This aspect was addressed by downshifting the solar irradiance on Earth through luminescent down-shifting layers based on lanthanidedoped surface-functionalized ionosilicas(ISs)embedded in poly(methyl methacrylate)(PMMA)coated on the surface of commercial Si-based PV cells.The IS-PMMA hybrid materials exhibit efficient solar radiation harvesting(spectral overlap of^9.5×10^19 photons/(s·m2))and conversion(quantum yield^52%).The direct solar radiation and the down-shifted radiation are partially guided and lost through total internal reflection to the layer edges being unavailable for PV conversion of the coated PV cell.By tuning the down-shifting layer thickness,it also acts as luminescent solar concentrator enabling the collection of the guided radiation by flexible PV cells applied on the borders of the down-shifting layer leading to an enhancement of the PV energy conversion from^5%(in the case of the single-use of the luminescent down-shifting layer)to^13%comparing with the bare PV cell.The overall electrical output of the device resulted in an absolute external quantum efficiency increase of^32%for the optimized Eu^3+-based films in the UV spectral region(compared with the bare PV device,which is among the best values reported so far).展开更多
There is an increased interest in renewable forms of energy across the world,with solar energy being one of the most promising forms.Over the last couple of years,we have developed the MET(MicroEquipment Technology).A...There is an increased interest in renewable forms of energy across the world,with solar energy being one of the most promising forms.Over the last couple of years,we have developed the MET(MicroEquipment Technology).As an application of the MET,we selected the task of production of solar concentrators.Different types of solar concentrators with flat mirrors were developed and prototypes of these solar concentrators(approximately 1 m in diameter)were made.The proposed solar concentrators were developed on the basis of concentrators patented in Mexico,Spain,and USA.It may be possible to install these concentrators on horizontal roofs of buildings.However,installing them on agricultural fields has become the new trend.As an example,we propose to use them in the potato fields in Canada to obtain dual advantages such as for electrical energy generation and for the minimal loss of agricultural harvest.The second example was analyzed for bean fields,in Mexico.In this paper,we describe the main results in regard to microequipment development for solar concentrator production,several prototypes of solar concentrators with flat mirrors and their co-location and agricultural fields.展开更多
Facile and efficient method for constructing carbon dots(CDs)with narrow full width at half maximum(FWHM)is a major challenge in the field,and researches on regulating the FWHM of CDs are also rare and scarce.In this ...Facile and efficient method for constructing carbon dots(CDs)with narrow full width at half maximum(FWHM)is a major challenge in the field,and researches on regulating the FWHM of CDs are also rare and scarce.In this work,we delved into the synthesis of CDs with narrow fluorescence emission FWHM(NFEF-CDs)in the m-phenylenediamine(m-PD)/ethanol system,utilizing solid superacid resin as cata-lyst with solvothermal method.The resulting NFEF-CDs exhibit a photoluminescent(PL)emission peak at 521 nm with a narrow FWHM of 41 nm,an absolute PL quantum yield(QY)of 80%,and display excitation-independent PL behavior.Through comprehensive characterization,we identified the protonation of edge amino on NFEF-CDs as the key factor in achieving the narrow FWHM.Subsequently,we validated the broad applicability of solid superacid resins as catalysts for synthesizing CDs with narrow FWHM in the m-PD/ethanol system.Finally,we utilized a self-leveling method to prepare NFEF-CDs film on the surface of poly(methyl methacrylate)(PMMA)substrate and investigated the solid-state fluorescence properties of NFEF-CDs as well as their performance as luminescence solar concentrator(LSC)for photovoltaic conver-sion.The results revealed that the as-prepared LSC exhibit an internal quantum efficiency(η_(int))of 42.39%and an optical efficiency(η_(opt))of 0.68%.These findings demonstrate the promising prospects of NFEF-CDs in the field of LSCs and provide a theoretical basis for their application in photovoltaic conversion.展开更多
A unique method is proposed to encapsulate solar cells and improve their power conversion efficiency by using a millimeter-sized cylindrical lens array concentrator. Millimeter-sized epoxy resin polymer（ERP） cylindr...A unique method is proposed to encapsulate solar cells and improve their power conversion efficiency by using a millimeter-sized cylindrical lens array concentrator. Millimeter-sized epoxy resin polymer（ERP） cylindrical lens array concentrators are fabricated by the soft imprint technique based on polydimethylsiloxane stamps. The photovoltaic measurements show that millimeter-sized ERP cylindrical lens array concentrators can considerably improve the power conversion efficiency of silicon solar cells. The validity of the proposed method is proved by the coupled optical and electrical simulations. The designed solar cell devices with the advantages of high-efficiency and convenient cleaning are very useful in practical applications.展开更多
An analysis of the thermal characteristics of the industrial thermocompression heat pump systems is presented in this paper By using thermocompression, waste heat is thermotransformed to a higher temperature level to ...An analysis of the thermal characteristics of the industrial thermocompression heat pump systems is presented in this paper By using thermocompression, waste heat is thermotransformed to a higher temperature level to be convenient for its usage in thermal processes. The thermocompression heat pumps can be optimally applied in various industrial plants （production of fruit, grape and tomato concentrates, in beer, sugar and dairy industries, in chemical and pharmaceutical industries etc.）. The range of optimal application of the turbo compressor, screw compressor and ejector thermocompression is estimated. The complex thermal and flow phenomena in the processes of thermocompression, evaporation and condensation are discussed. The theoretical and experimental results of the investigations on the experimental grape vacuum concentrator and on the industrial NaOH concentrator are presented. A significant increment of the energy efficiency can be achieved by optimal application of the thermocompression in the thermal concentrating processes. A significant feature and great advantage of the concentrating technology with thermocompression are a possibility for realization of the low temperature concentrating processes, which is very important for the quality of many concentrating products with high energy efficiency technology.展开更多
There are a few standards reported in the literature for testing and evaluation of thermal performance of solar concentrators based on sensible heating of working fluid. The preceding standard measures only the cookin...There are a few standards reported in the literature for testing and evaluation of thermal performance of solar concentrators based on sensible heating of working fluid. The preceding standard measures only the cooking efficiency and cooking capacity. Apart from thermal efficiency, there is an imperative need for other important parameters of the solar concentrators such as its stagnation temperature, cooking capacity, cost per watts delivered, weight of the cooker, ease of handling and aesthetics. The characterization of a concentrator at its operating temperature settles appropriate size and type of concentrator for any thermal application. The performance test is conducted at Chandwad (20.3292°N, 74.2444°E), Maharashtra and the proposed protocol aims for evaluation of thermal performance of solar cooking system and standardization of reporting the test results so that anyone can easily recognize and use it.展开更多
A new trend involving the combination of solar concentrators and agricultural plants on the same piece of land offers the possibility of realizing both electricity generation and a good crop harvest.Authors analyze th...A new trend involving the combination of solar concentrators and agricultural plants on the same piece of land offers the possibility of realizing both electricity generation and a good crop harvest.Authors analyze this situation for different countries,including Mexico,and based on authors’experience regarding the development of new solar concentrator prototypes,authors’primary objective was to describe the development of compact,light,and inexpensive solar concentrator prototypes that can be collocated on horizontal roofs.Authors’second objective was to investigate the combination of such solar concentrator prototypes with agricultural plants on the same field.Thus,several studies related to the combination of renewable energy generation and agricultural crops were reviewed.Many such systems involving the combination of PV(Photovoltaic)panels with different types of vegetables exist in the USA,France(lettuce production),Japan(tomato production),India(aloe and corn),northern Italy(maize),Spain and México.展开更多
InP quantum dots(QDs)have been a major building block of modern display technology due to their high photoluminescence quantum yield(PLQY)in the visible spectrum,superior stability,and eco-friendly composition.However...InP quantum dots(QDs)have been a major building block of modern display technology due to their high photoluminescence quantum yield(PLQY)in the visible spectrum,superior stability,and eco-friendly composition.However,their applications at short-wave infrared(SWIR)have been hindered by their low efficiency.Here,we report the synthesis of efficient and SWIR-emitting InP QDs by precisely controlling the InP core nucleation using a low-cost ammonia phosphorus precursor,while avoiding size-limiting ZnCl_(2) for effective copper doping.Subsequent epitaxial growth of a lattice-matched ZnSe/ZnS multishell enhanced the QD sphericity and surface smoothness and yielded a record PLQY of 66% with an emission peak at 960 nm.When QDs were integrated as the high-refractive-index luminescent core of a liquid waveguide-based luminescent solar concentrator(LSC),the device achieved an optical efficiency of 7.36%.This performance arises from their high PLQY,spectral alignment with the responsivity peak of silicon solar cells,and the optimized core/cladding waveguide structure.These results highlight the potential of InP QDs as a promising nanomaterial for SWIR emission and applications.展开更多
Carbon dots(CDs)have emerged as a promising platform for constructing optoelectronic devices.However,the synthesis of multicolor CDs with high quantum yield(QY)and the elucidation of their luminescence mechanisms rema...Carbon dots(CDs)have emerged as a promising platform for constructing optoelectronic devices.However,the synthesis of multicolor CDs with high quantum yield(QY)and the elucidation of their luminescence mechanisms remain challenges.Here,we successfully synthesize RGB-CDs by precisely controlling the ratio of o-phenylenediamine and phytic acid.The QYs of the RGB-CDs are up to 60.3%,68.7%,and 19.0%,respectively.Experimental data and DFT calculations reveal that the fluorescence emission of the RGB-CDs originates from molecule state(5,14-dihydroquinoxalino[2,3-b]phenazine),carbon core state,and clusteroluminescence state induced by the through-space interactions of heteroatom groups,respectively.Moreover,leveraging the outstanding fluorescence properties of the RGB-CDs,we fabricate both a white light-emitting diode(WLED)with an ultra-high color rendering index of 98 and a luminescent solar concentrator achieving a high power conversion efficiency of 1.6%.Finally,we integrate a self-powered lighting system combining the WLED and LSC,which provides approximately 6 h of continuous illumination to a 0.1WWLED after a single day’s charging.Our results demonstrate a facilemethod for preparing multicolor CDs with high QYs,enabling their use as phosphor sources for various optoelectronic device applications.展开更多
Luminescent solar concentrators (LSC) absorb large-area solar radiation and guide down-converted emission to solar cells for electricity production. Quantum dots (QDs) have been widely engineered at device and quantum...Luminescent solar concentrators (LSC) absorb large-area solar radiation and guide down-converted emission to solar cells for electricity production. Quantum dots (QDs) have been widely engineered at device and quantum dot levels for LSCs. Here, we demonstrate cascaded energy transfer and exciton recycling at nanoassembly level for LSCs. The graded structure composed of different sized toxic-heavy-metal-free InP/ZnS core/shell QDs incorporated on copper doped InP QDs, facilitating exciton routing toward narrow band gap QDs at a high nonradiative energy transfer efficiency of 66%. At the final stage of non-radiative energy transfer, the photogenerated holes make ultrafast electronic transitions to copper-induced mid-gap states for radiative recombination in the near-infrared. The exciton recycling facilitates a photoluminescence quantum yield increase of 34% and 61% in comparison with semi-graded and ungraded energy profiles, respectively. Thanks to the suppressed reabsorption and enhanced photoluminescence quantum yield, the graded LSC achieved an optical quantum efficiency of 22.2%. Hence, engineering at nanoassembly level combined with nonradiative energy transfer and exciton funneling offer promise for efficient solar energy harvesting.展开更多
Current shipping,tourism,and resource development requirements call for more accurate predictions of the Arctic sea-ice concentration(SIC).However,due to the complex physical processes involved,predicting the spatiote...Current shipping,tourism,and resource development requirements call for more accurate predictions of the Arctic sea-ice concentration(SIC).However,due to the complex physical processes involved,predicting the spatiotemporal distribution of Arctic SIC is more challenging than predicting its total extent.In this study,spatiotemporal prediction models for monthly Arctic SIC at 1-to 3-month leads are developed based on U-Net-an effective convolutional deep-learning approach.Based on explicit Arctic sea-ice-atmosphere interactions,11 variables associated with Arctic sea-ice variations are selected as predictors,including observed Arctic SIC,atmospheric,oceanic,and heat flux variables at 1-to 3-month leads.The prediction skills for the monthly Arctic SIC of the test set(from January 2018 to December 2022)are evaluated by examining the mean absolute error(MAE)and binary accuracy(BA).Results showed that the U-Net model had lower MAE and higher BA for Arctic SIC compared to two dynamic climate prediction systems(CFSv2 and NorCPM).By analyzing the relative importance of each predictor,the prediction accuracy relies more on the SIC at the 1-month lead,but on the surface net solar radiation flux at 2-to 3-month leads.However,dynamic models show limited prediction skills for surface net solar radiation flux and other physical processes,especially in autumn.Therefore,the U-Net model can be used to capture the connections among these key physical processes associated with Arctic sea ice and thus offers a significant advantage in predicting Arctic SIC.展开更多
BACKGROUND Orthobiologics-biological substances like platelet-rich plasma(PRP),bone marrow aspirate concentrate,and stem cells-are increasingly used in musculoskeletal care to promote tissue repair and reduce reliance...BACKGROUND Orthobiologics-biological substances like platelet-rich plasma(PRP),bone marrow aspirate concentrate,and stem cells-are increasingly used in musculoskeletal care to promote tissue repair and reduce reliance on invasive surgery.Despite global momentum,India's clinical adoption remains underexplored.AIM To inform education,policy,and resource allocation for the safe and effective adoption of orthobiologics in musculoskeletal care.METHODS A cross-sectional electronic survey was conducted from January to March 2025 among orthopaedic surgeons,academicians,and trainees across India.The questionnaire assessed demographics,knowledge of orthobiologics,attitudes toward training and subspecialization,usage trends,regulatory awareness,and perceived barriers.Data were analyzed using descriptive statistics andχ2/Fisher’s exact tests,with P<0.05 considered significant.RESULTS A total of 1280 valid responses were collected.Awareness of orthobiologics was high(97%),with PRP being the most familiar and widely used(80%).Formal training was reported by only 31%,though 85%showed interest in structured education,and 68%supported orthobiologics as a subspecialty.Satisfaction with clinical outcomes averaged 6.5±2.3 out of 10 points.Barriers included high treatment cost(64%),poor patient awareness(90%),and limited access to biologics labs(18%).Regulatory understanding was moderate,with academic-affiliated clinicians more informed about stem cell guidelines.CONCLUSION Indian orthopaedic professionals demonstrate strong awareness and optimism toward orthobiologics,but widespread gaps in training,infrastructure,and regulation hinder broader adoption.Strategic investments in education,standardized protocols,and accessible facilities are essential to support safe and evidence-driven integration of regenerative therapies into clinical practice.展开更多
Cemented paste backfill(CPB)is a technology that achieves safe mining by filling the goaf with waste rocks,tailings,and other materials.It is an inevitable choice to deal with the development of deep and highly diffic...Cemented paste backfill(CPB)is a technology that achieves safe mining by filling the goaf with waste rocks,tailings,and other materials.It is an inevitable choice to deal with the development of deep and highly difficult mines and meet the requirements of environmental protection and safety regulations.It promotes the development of a circular economy in mines through the development of lowgrade resources and the resource utilization of waste,and extends the service life of mines.The mass concentration of solid content(abbreviated as“concentration”)is a critical parameter for CPB.However,discrepancies often arise between the on-site measurements and the pre-designed values due to factors such as groundwater inflow and segregation within the goaf,which cannot be evaluated after the solidification of CPB.This paper innovatively provides an in-situ non-destructive approach to identify the real concentration of CPB after curing for certain days using hyperspectral imaging(HSI)technology.Initially,the spectral variation patterns under different concentration conditions were investigated through hyperspectral scanning experiments on CPB samples.The results demonstrate that as the CPB concentration increases from 61wt%to 73wt%,the overall spectral reflectance gradually increases,with two distinct absorption peaks observed at 1407 and 1917 nm.Notably,the reflectance at 1407 nm exhibited a strong linear relationship with the concentration.Subsequently,the K-nearest neighbors(KNN)and support vector machine(SVM)algorithms were employed to classify and identify different concentrations.The study revealed that,with the KNN algorithm,the highest accuracy was achieved when K(number of nearest neighbors)was 1,although this resulted in overfitting.When K=3,the model displayed the optimal balance between accuracy and stability,with an accuracy of 95.03%.In the SVM algorithm,the highest accuracy of 98.24%was attained with parameters C(regularization parameter)=200 and Gamma(kernel coefficient)=10.A comparative analysis of precision,accuracy,and recall further highlighted that the SVM provided superior stability and precision for identifying CPB concentration.Thus,HSI technology offers an effective solution for the in-situ,non-destructive monitoring of CPB concentration,presenting a promising approach for optimizing and controlling CPB characteristic parameters.展开更多
This study examines the use of an aggregation-induced enhanced emission fluorophore(TPE-MRh)to prepare red-emitting luminescent solar concentrators(LSCs)based on poly(methyl methacrylate)(PMMA)and poly(cyclohexyl meth...This study examines the use of an aggregation-induced enhanced emission fluorophore(TPE-MRh)to prepare red-emitting luminescent solar concentrators(LSCs)based on poly(methyl methacrylate)(PMMA)and poly(cyclohexyl methacrylate)(PCMA).TPE-MRh is a tetraphenylethylene(TPE)derivative bearing two dimethylamino push groups and a 3-methyl-rhodanine pull moiety,with absorption maxima at around 500 nm and fluorescence peak at 700 nm that strongly increases in solid-state.TPE-MRh displays a typical crystallizationinduced enhanced emission that has been rationalized by modeling the compound behavior in solution and solid-state via density functional theory calculations with the inclusion of the environment.TPE-MRh dispersed into 5×5 cm2 polymer films with a thickness of 25±5μm has revealed a partial fluorescence quenching with fluorophore content.Quantum yields(QYs)below 10%for the 2 wt.%of doping have been addressed to the formation of less emissive micro-sized clusters of fluorophores.PMMA slabs with the same surface size but 3 mm of thickness and 200 ppm of TPE-MRh have provided QY of 36.5%thanks to the attenuation of the detrimental effects of fluorophore aggregation.This feature is reflected in the LSCs performance,with devices achieving the largest power collected by the photovoltaic cell.展开更多
The technology of small point-focusing concentrator of solar energy has been developing rapidly in recent years owing to its compact structure and high collecting efficiency. This report presents important development...The technology of small point-focusing concentrator of solar energy has been developing rapidly in recent years owing to its compact structure and high collecting efficiency. This report presents important developments of small point-focusing concentrator in the past decade. This kind of solar concentrator refers to the parabolic dish concentrator, the point-focusing Fresnel lens, and the Scheffler reflector. Technological advances of these concentrators and the related performances have been presented. There are three main mirror fabrication technologies for dish concentrator, which are high polishing metal, silver-glass mirror and vacuum-membrane. Polymethyl methacrylate is widely used as material in Fresnel lens. Many scholars have proposed new lens shape to improve the uniformity of focusing. The Scheffler reflector has a characteristic of fixed focus, but its design parameters are not perfect so current research focuses on the theoretical calculation of the mirror. In addition, typical applications of the small point-focusing concentrator in photovoltaic system, solar thermal system, solar chemical system, and day-lighting system are summarized. Upon listing the important publications in open literature, a category of main applications of such kind of solar collector is provided based on the working characteristics of the system.展开更多
A square-shaped heat flux cloak and a square-shaped heat flux concentrator have been designed the- oretically according to the invariance symmetry of steady state thermal conductive equation. The direction of heat flu...A square-shaped heat flux cloak and a square-shaped heat flux concentrator have been designed the- oretically according to the invariance symmetry of steady state thermal conductive equation. The direction of heat flux in these devices can be modulated as desired. Using the method of coordinate transformation, the inhomogeneous and anisotropic thermal conductivity in the transformation region have been acquired. Two-dimensional finite element simulations were performed to confirm the theoretical results.展开更多
We propose a simple method to design field concentrators of arbitrary shapes based on Fabry-Perot resonances. The material parameters are feasible in terms of metallic layered structures and gradient index dielectrics...We propose a simple method to design field concentrators of arbitrary shapes based on Fabry-Perot resonances. The material parameters are feasible in terms of metallic layered structures and gradient index dielectrics. The functionalities are well confirmed by numerical simulations.展开更多
Practical solar energy solutions must not only reduce the cost of the module,but also address the substantial balance of system costs.Here,we demonstrate a counter-intuitive approach based on gallium arsenide solar ce...Practical solar energy solutions must not only reduce the cost of the module,but also address the substantial balance of system costs.Here,we demonstrate a counter-intuitive approach based on gallium arsenide solar cells that can achieve extremely low-cost solar energy conversion with an estimated cost of only 3% that of conventional gallium arsenide solar cells using an accelerated,non-destructive epitaxial lift-off wafer recycling process along with a lightweight,thermoformed plastic,truncated mini-compound parabolic concentrator that avoids the need for active solar tracking.Using solar cell/concentrator assemblies whose orientations are adjusted only a few times per year,the annual energy harvesting is increased by 2.8 times compared with planar solar cells without solar tracking.These results represent a potentially drastic cost reduction in both the module and the balance of system costs compared with heavy,rigid conventional modules and trackers that are subject to wind loading damage and high installation costs.展开更多
The concentrating efficiency of a thermal concentrator can be reflected in the ratio of its interior to exterior temperature gradients,which, however, has an upper limit in existing schemes. Here, we manage to break t...The concentrating efficiency of a thermal concentrator can be reflected in the ratio of its interior to exterior temperature gradients,which, however, has an upper limit in existing schemes. Here, we manage to break this upper limit by considering the couplings of thermal conductivities and improve the concentrating efficiency of thermal concentrators. For this purpose, we first discuss a monolayer scheme with an isotropic thermal conductivity, which can break the upper limit but is still restricted by its geometric configuration. To go further, we explore another degree of freedom by considering the monolayer scheme with an anisotropic thermal conductivity or by adding the second shell with an isotropic thermal conductivity, thereby making the concentrating efficiency completely free from the geometric configuration. Nevertheless, apparent negative thermal conductivities are required, and we resort to external heat sources realizing the same effect without violating the second law of thermodynamics. Finite-element simulations are performed to confirm the theoretical predictions, and experimental suggestions are also provided to improve feasibility. These results may have potential applications for thermal camouflage and provide guidance to other diffusive systems such as static magnetic fields and dc current fields for achieving similar behaviors.展开更多
Solar energy is an inexhaustible renewable energy resource,which is a potential solution to global warming and aids sustainable development.The use of solar-thermal collectors to harness solar energy facilitates low-c...Solar energy is an inexhaustible renewable energy resource,which is a potential solution to global warming and aids sustainable development.The use of solar-thermal collectors to harness solar energy facilitates low-cost heat storage and can improve the stability of power grids based on renewable energy.In solar-thermal collectors,traditional concentrators,such as parabolic troughs and dishes,are typically used but inevitably require high-precise supports and complex tracking sun systems,which increase the cost of solar-thermal power stations and hinder their further applications.In contrast,planar meta-lenses(so-called metasurface-based concentrators)consisting of two-dimensional nanostructured arrays are allowed to engineer the frequency dispersion and angular dispersion of the incident light through delicately arranging the aperture phase distribution,thereby correcting their inherent aberrations.Accordingly,the novel meta-lenses offer tremendous potentials to effectively capture broadband,wide-angle sunlight without the extra tracking system.This review summarizes the research motivation,design principles,building materials,and large-area fabrication methods of meta-lens for solar energy harvesting in terms of focusing efficiency,operation bandwidth,and angular dependence.In addition,the main challenges and future goals are examined.展开更多
基金Project supported by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership in the frame of Operational Competitiveness and Internationalization Programme(projects UIDB/50011/2020&UIDP/50011/2020,UID/EEA/50008/2020,UID/QUI/50006/2019,CENTRO-01-0145-FEDER-030186,CENTRO-01-0145-FEDER-000005,Pest-OE/QUI/UI0616/2014,POCI-01-0145-FEDER-016884,PTDC/CTM-NAN/0956/2014,UID/QUI/00686/2016,UID/QUI/00686/2018,UID/QUI/00686/2019 and NORTE-01-0145-FEDER-030858)。
文摘The mismatch between the photovoltaic(PV)cells absorption and the solar irradiance on earth is one of the major limitations towards more efficient PV energy conversion.This aspect was addressed by downshifting the solar irradiance on Earth through luminescent down-shifting layers based on lanthanidedoped surface-functionalized ionosilicas(ISs)embedded in poly(methyl methacrylate)(PMMA)coated on the surface of commercial Si-based PV cells.The IS-PMMA hybrid materials exhibit efficient solar radiation harvesting(spectral overlap of^9.5×10^19 photons/(s·m2))and conversion(quantum yield^52%).The direct solar radiation and the down-shifted radiation are partially guided and lost through total internal reflection to the layer edges being unavailable for PV conversion of the coated PV cell.By tuning the down-shifting layer thickness,it also acts as luminescent solar concentrator enabling the collection of the guided radiation by flexible PV cells applied on the borders of the down-shifting layer leading to an enhancement of the PV energy conversion from^5%(in the case of the single-use of the luminescent down-shifting layer)to^13%comparing with the bare PV cell.The overall electrical output of the device resulted in an absolute external quantum efficiency increase of^32%for the optimized Eu^3+-based films in the UV spectral region(compared with the bare PV device,which is among the best values reported so far).
文摘There is an increased interest in renewable forms of energy across the world,with solar energy being one of the most promising forms.Over the last couple of years,we have developed the MET(MicroEquipment Technology).As an application of the MET,we selected the task of production of solar concentrators.Different types of solar concentrators with flat mirrors were developed and prototypes of these solar concentrators(approximately 1 m in diameter)were made.The proposed solar concentrators were developed on the basis of concentrators patented in Mexico,Spain,and USA.It may be possible to install these concentrators on horizontal roofs of buildings.However,installing them on agricultural fields has become the new trend.As an example,we propose to use them in the potato fields in Canada to obtain dual advantages such as for electrical energy generation and for the minimal loss of agricultural harvest.The second example was analyzed for bean fields,in Mexico.In this paper,we describe the main results in regard to microequipment development for solar concentrator production,several prototypes of solar concentrators with flat mirrors and their co-location and agricultural fields.
基金supported by the National Natural Science Foundation of China(No.22308161)the Jiangsu Funding Program for Excellent Postdoctoral Talent(No.2022ZB369),Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘Facile and efficient method for constructing carbon dots(CDs)with narrow full width at half maximum(FWHM)is a major challenge in the field,and researches on regulating the FWHM of CDs are also rare and scarce.In this work,we delved into the synthesis of CDs with narrow fluorescence emission FWHM(NFEF-CDs)in the m-phenylenediamine(m-PD)/ethanol system,utilizing solid superacid resin as cata-lyst with solvothermal method.The resulting NFEF-CDs exhibit a photoluminescent(PL)emission peak at 521 nm with a narrow FWHM of 41 nm,an absolute PL quantum yield(QY)of 80%,and display excitation-independent PL behavior.Through comprehensive characterization,we identified the protonation of edge amino on NFEF-CDs as the key factor in achieving the narrow FWHM.Subsequently,we validated the broad applicability of solid superacid resins as catalysts for synthesizing CDs with narrow FWHM in the m-PD/ethanol system.Finally,we utilized a self-leveling method to prepare NFEF-CDs film on the surface of poly(methyl methacrylate)(PMMA)substrate and investigated the solid-state fluorescence properties of NFEF-CDs as well as their performance as luminescence solar concentrator(LSC)for photovoltaic conver-sion.The results revealed that the as-prepared LSC exhibit an internal quantum efficiency(η_(int))of 42.39%and an optical efficiency(η_(opt))of 0.68%.These findings demonstrate the promising prospects of NFEF-CDs in the field of LSCs and provide a theoretical basis for their application in photovoltaic conversion.
基金Project supported by the Natural National Science Foundation of China(Grant No.61377021)
文摘A unique method is proposed to encapsulate solar cells and improve their power conversion efficiency by using a millimeter-sized cylindrical lens array concentrator. Millimeter-sized epoxy resin polymer（ERP） cylindrical lens array concentrators are fabricated by the soft imprint technique based on polydimethylsiloxane stamps. The photovoltaic measurements show that millimeter-sized ERP cylindrical lens array concentrators can considerably improve the power conversion efficiency of silicon solar cells. The validity of the proposed method is proved by the coupled optical and electrical simulations. The designed solar cell devices with the advantages of high-efficiency and convenient cleaning are very useful in practical applications.
文摘An analysis of the thermal characteristics of the industrial thermocompression heat pump systems is presented in this paper By using thermocompression, waste heat is thermotransformed to a higher temperature level to be convenient for its usage in thermal processes. The thermocompression heat pumps can be optimally applied in various industrial plants （production of fruit, grape and tomato concentrates, in beer, sugar and dairy industries, in chemical and pharmaceutical industries etc.）. The range of optimal application of the turbo compressor, screw compressor and ejector thermocompression is estimated. The complex thermal and flow phenomena in the processes of thermocompression, evaporation and condensation are discussed. The theoretical and experimental results of the investigations on the experimental grape vacuum concentrator and on the industrial NaOH concentrator are presented. A significant increment of the energy efficiency can be achieved by optimal application of the thermocompression in the thermal concentrating processes. A significant feature and great advantage of the concentrating technology with thermocompression are a possibility for realization of the low temperature concentrating processes, which is very important for the quality of many concentrating products with high energy efficiency technology.
文摘There are a few standards reported in the literature for testing and evaluation of thermal performance of solar concentrators based on sensible heating of working fluid. The preceding standard measures only the cooking efficiency and cooking capacity. Apart from thermal efficiency, there is an imperative need for other important parameters of the solar concentrators such as its stagnation temperature, cooking capacity, cost per watts delivered, weight of the cooker, ease of handling and aesthetics. The characterization of a concentrator at its operating temperature settles appropriate size and type of concentrator for any thermal application. The performance test is conducted at Chandwad (20.3292°N, 74.2444°E), Maharashtra and the proposed protocol aims for evaluation of thermal performance of solar cooking system and standardization of reporting the test results so that anyone can easily recognize and use it.
基金This work was partly supported by the UNAM-DGAPA-IT102320 project.
文摘A new trend involving the combination of solar concentrators and agricultural plants on the same piece of land offers the possibility of realizing both electricity generation and a good crop harvest.Authors analyze this situation for different countries,including Mexico,and based on authors’experience regarding the development of new solar concentrator prototypes,authors’primary objective was to describe the development of compact,light,and inexpensive solar concentrator prototypes that can be collocated on horizontal roofs.Authors’second objective was to investigate the combination of such solar concentrator prototypes with agricultural plants on the same field.Thus,several studies related to the combination of renewable energy generation and agricultural crops were reviewed.Many such systems involving the combination of PV(Photovoltaic)panels with different types of vegetables exist in the USA,France(lettuce production),Japan(tomato production),India(aloe and corn),northern Italy(maize),Spain and México.
文摘InP quantum dots(QDs)have been a major building block of modern display technology due to their high photoluminescence quantum yield(PLQY)in the visible spectrum,superior stability,and eco-friendly composition.However,their applications at short-wave infrared(SWIR)have been hindered by their low efficiency.Here,we report the synthesis of efficient and SWIR-emitting InP QDs by precisely controlling the InP core nucleation using a low-cost ammonia phosphorus precursor,while avoiding size-limiting ZnCl_(2) for effective copper doping.Subsequent epitaxial growth of a lattice-matched ZnSe/ZnS multishell enhanced the QD sphericity and surface smoothness and yielded a record PLQY of 66% with an emission peak at 960 nm.When QDs were integrated as the high-refractive-index luminescent core of a liquid waveguide-based luminescent solar concentrator(LSC),the device achieved an optical efficiency of 7.36%.This performance arises from their high PLQY,spectral alignment with the responsivity peak of silicon solar cells,and the optimized core/cladding waveguide structure.These results highlight the potential of InP QDs as a promising nanomaterial for SWIR emission and applications.
基金support from the National Natural Science Foundation of China(52302051)the Foundational Research Project of Shanxi Province(202303021221115)the Graduate Innovation Project of Shanxi Province(2024SJ295).
文摘Carbon dots(CDs)have emerged as a promising platform for constructing optoelectronic devices.However,the synthesis of multicolor CDs with high quantum yield(QY)and the elucidation of their luminescence mechanisms remain challenges.Here,we successfully synthesize RGB-CDs by precisely controlling the ratio of o-phenylenediamine and phytic acid.The QYs of the RGB-CDs are up to 60.3%,68.7%,and 19.0%,respectively.Experimental data and DFT calculations reveal that the fluorescence emission of the RGB-CDs originates from molecule state(5,14-dihydroquinoxalino[2,3-b]phenazine),carbon core state,and clusteroluminescence state induced by the through-space interactions of heteroatom groups,respectively.Moreover,leveraging the outstanding fluorescence properties of the RGB-CDs,we fabricate both a white light-emitting diode(WLED)with an ultra-high color rendering index of 98 and a luminescent solar concentrator achieving a high power conversion efficiency of 1.6%.Finally,we integrate a self-powered lighting system combining the WLED and LSC,which provides approximately 6 h of continuous illumination to a 0.1WWLED after a single day’s charging.Our results demonstrate a facilemethod for preparing multicolor CDs with high QYs,enabling their use as phosphor sources for various optoelectronic device applications.
基金This project has received funding from the European Research Council(ERC)under the European Union Horizon 2020 Research and Innovation Programme(grant agreement no.639846).
文摘Luminescent solar concentrators (LSC) absorb large-area solar radiation and guide down-converted emission to solar cells for electricity production. Quantum dots (QDs) have been widely engineered at device and quantum dot levels for LSCs. Here, we demonstrate cascaded energy transfer and exciton recycling at nanoassembly level for LSCs. The graded structure composed of different sized toxic-heavy-metal-free InP/ZnS core/shell QDs incorporated on copper doped InP QDs, facilitating exciton routing toward narrow band gap QDs at a high nonradiative energy transfer efficiency of 66%. At the final stage of non-radiative energy transfer, the photogenerated holes make ultrafast electronic transitions to copper-induced mid-gap states for radiative recombination in the near-infrared. The exciton recycling facilitates a photoluminescence quantum yield increase of 34% and 61% in comparison with semi-graded and ungraded energy profiles, respectively. Thanks to the suppressed reabsorption and enhanced photoluminescence quantum yield, the graded LSC achieved an optical quantum efficiency of 22.2%. Hence, engineering at nanoassembly level combined with nonradiative energy transfer and exciton funneling offer promise for efficient solar energy harvesting.
基金supported by the National Key Research and Development Program of China[grant number 2022YFE0106800]an Innovation Group Project of the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)[grant number 311024001]+3 种基金a project supported by the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)[grant number SML2023SP209]a Research Council of Norway funded project(MAPARC)[grant number 328943]a Nansen Center´s basic institutional funding[grant number 342624]the high-performance computing support from the School of Atmospheric Science at Sun Yat-sen University。
文摘Current shipping,tourism,and resource development requirements call for more accurate predictions of the Arctic sea-ice concentration(SIC).However,due to the complex physical processes involved,predicting the spatiotemporal distribution of Arctic SIC is more challenging than predicting its total extent.In this study,spatiotemporal prediction models for monthly Arctic SIC at 1-to 3-month leads are developed based on U-Net-an effective convolutional deep-learning approach.Based on explicit Arctic sea-ice-atmosphere interactions,11 variables associated with Arctic sea-ice variations are selected as predictors,including observed Arctic SIC,atmospheric,oceanic,and heat flux variables at 1-to 3-month leads.The prediction skills for the monthly Arctic SIC of the test set(from January 2018 to December 2022)are evaluated by examining the mean absolute error(MAE)and binary accuracy(BA).Results showed that the U-Net model had lower MAE and higher BA for Arctic SIC compared to two dynamic climate prediction systems(CFSv2 and NorCPM).By analyzing the relative importance of each predictor,the prediction accuracy relies more on the SIC at the 1-month lead,but on the surface net solar radiation flux at 2-to 3-month leads.However,dynamic models show limited prediction skills for surface net solar radiation flux and other physical processes,especially in autumn.Therefore,the U-Net model can be used to capture the connections among these key physical processes associated with Arctic sea ice and thus offers a significant advantage in predicting Arctic SIC.
文摘BACKGROUND Orthobiologics-biological substances like platelet-rich plasma(PRP),bone marrow aspirate concentrate,and stem cells-are increasingly used in musculoskeletal care to promote tissue repair and reduce reliance on invasive surgery.Despite global momentum,India's clinical adoption remains underexplored.AIM To inform education,policy,and resource allocation for the safe and effective adoption of orthobiologics in musculoskeletal care.METHODS A cross-sectional electronic survey was conducted from January to March 2025 among orthopaedic surgeons,academicians,and trainees across India.The questionnaire assessed demographics,knowledge of orthobiologics,attitudes toward training and subspecialization,usage trends,regulatory awareness,and perceived barriers.Data were analyzed using descriptive statistics andχ2/Fisher’s exact tests,with P<0.05 considered significant.RESULTS A total of 1280 valid responses were collected.Awareness of orthobiologics was high(97%),with PRP being the most familiar and widely used(80%).Formal training was reported by only 31%,though 85%showed interest in structured education,and 68%supported orthobiologics as a subspecialty.Satisfaction with clinical outcomes averaged 6.5±2.3 out of 10 points.Barriers included high treatment cost(64%),poor patient awareness(90%),and limited access to biologics labs(18%).Regulatory understanding was moderate,with academic-affiliated clinicians more informed about stem cell guidelines.CONCLUSION Indian orthopaedic professionals demonstrate strong awareness and optimism toward orthobiologics,but widespread gaps in training,infrastructure,and regulation hinder broader adoption.Strategic investments in education,standardized protocols,and accessible facilities are essential to support safe and evidence-driven integration of regenerative therapies into clinical practice.
基金funded by the National Natural Science Foundation of China(Nos.52474165 and 52522404)。
文摘Cemented paste backfill(CPB)is a technology that achieves safe mining by filling the goaf with waste rocks,tailings,and other materials.It is an inevitable choice to deal with the development of deep and highly difficult mines and meet the requirements of environmental protection and safety regulations.It promotes the development of a circular economy in mines through the development of lowgrade resources and the resource utilization of waste,and extends the service life of mines.The mass concentration of solid content(abbreviated as“concentration”)is a critical parameter for CPB.However,discrepancies often arise between the on-site measurements and the pre-designed values due to factors such as groundwater inflow and segregation within the goaf,which cannot be evaluated after the solidification of CPB.This paper innovatively provides an in-situ non-destructive approach to identify the real concentration of CPB after curing for certain days using hyperspectral imaging(HSI)technology.Initially,the spectral variation patterns under different concentration conditions were investigated through hyperspectral scanning experiments on CPB samples.The results demonstrate that as the CPB concentration increases from 61wt%to 73wt%,the overall spectral reflectance gradually increases,with two distinct absorption peaks observed at 1407 and 1917 nm.Notably,the reflectance at 1407 nm exhibited a strong linear relationship with the concentration.Subsequently,the K-nearest neighbors(KNN)and support vector machine(SVM)algorithms were employed to classify and identify different concentrations.The study revealed that,with the KNN algorithm,the highest accuracy was achieved when K(number of nearest neighbors)was 1,although this resulted in overfitting.When K=3,the model displayed the optimal balance between accuracy and stability,with an accuracy of 95.03%.In the SVM algorithm,the highest accuracy of 98.24%was attained with parameters C(regularization parameter)=200 and Gamma(kernel coefficient)=10.A comparative analysis of precision,accuracy,and recall further highlighted that the SVM provided superior stability and precision for identifying CPB concentration.Thus,HSI technology offers an effective solution for the in-situ,non-destructive monitoring of CPB concentration,presenting a promising approach for optimizing and controlling CPB characteristic parameters.
基金MIUR-PRIN,Grant/Award Number:20179BJNA2European Union’s Horizon 2020 Research and Innovation Program,Grant/Award Number:648558China Scholarship Council,Grant/Award Number:202006890004。
文摘This study examines the use of an aggregation-induced enhanced emission fluorophore(TPE-MRh)to prepare red-emitting luminescent solar concentrators(LSCs)based on poly(methyl methacrylate)(PMMA)and poly(cyclohexyl methacrylate)(PCMA).TPE-MRh is a tetraphenylethylene(TPE)derivative bearing two dimethylamino push groups and a 3-methyl-rhodanine pull moiety,with absorption maxima at around 500 nm and fluorescence peak at 700 nm that strongly increases in solid-state.TPE-MRh displays a typical crystallizationinduced enhanced emission that has been rationalized by modeling the compound behavior in solution and solid-state via density functional theory calculations with the inclusion of the environment.TPE-MRh dispersed into 5×5 cm2 polymer films with a thickness of 25±5μm has revealed a partial fluorescence quenching with fluorophore content.Quantum yields(QYs)below 10%for the 2 wt.%of doping have been addressed to the formation of less emissive micro-sized clusters of fluorophores.PMMA slabs with the same surface size but 3 mm of thickness and 200 ppm of TPE-MRh have provided QY of 36.5%thanks to the attenuation of the detrimental effects of fluorophore aggregation.This feature is reflected in the LSCs performance,with devices achieving the largest power collected by the photovoltaic cell.
基金sponsored by the National Key Basic Research Program of China (No. 2015CB251303)
文摘The technology of small point-focusing concentrator of solar energy has been developing rapidly in recent years owing to its compact structure and high collecting efficiency. This report presents important developments of small point-focusing concentrator in the past decade. This kind of solar concentrator refers to the parabolic dish concentrator, the point-focusing Fresnel lens, and the Scheffler reflector. Technological advances of these concentrators and the related performances have been presented. There are three main mirror fabrication technologies for dish concentrator, which are high polishing metal, silver-glass mirror and vacuum-membrane. Polymethyl methacrylate is widely used as material in Fresnel lens. Many scholars have proposed new lens shape to improve the uniformity of focusing. The Scheffler reflector has a characteristic of fixed focus, but its design parameters are not perfect so current research focuses on the theoretical calculation of the mirror. In addition, typical applications of the small point-focusing concentrator in photovoltaic system, solar thermal system, solar chemical system, and day-lighting system are summarized. Upon listing the important publications in open literature, a category of main applications of such kind of solar collector is provided based on the working characteristics of the system.
基金Acknowledgements This work was supported by the National Natural Science Foundation of China （Grant No. 3670156）.
文摘A square-shaped heat flux cloak and a square-shaped heat flux concentrator have been designed the- oretically according to the invariance symmetry of steady state thermal conductive equation. The direction of heat flux in these devices can be modulated as desired. Using the method of coordinate transformation, the inhomogeneous and anisotropic thermal conductivity in the transformation region have been acquired. Two-dimensional finite element simulations were performed to confirm the theoretical results.
基金This work was supported by the Fun- damental Research Funds for the Central Universities （Grant No. 20720170015） and the National Natural Science Foundation of China for Excellent Young Scientists （Grant No. 61322504）.
文摘We propose a simple method to design field concentrators of arbitrary shapes based on Fabry-Perot resonances. The material parameters are feasible in terms of metallic layered structures and gradient index dielectrics. The functionalities are well confirmed by numerical simulations.
文摘Practical solar energy solutions must not only reduce the cost of the module,but also address the substantial balance of system costs.Here,we demonstrate a counter-intuitive approach based on gallium arsenide solar cells that can achieve extremely low-cost solar energy conversion with an estimated cost of only 3% that of conventional gallium arsenide solar cells using an accelerated,non-destructive epitaxial lift-off wafer recycling process along with a lightweight,thermoformed plastic,truncated mini-compound parabolic concentrator that avoids the need for active solar tracking.Using solar cell/concentrator assemblies whose orientations are adjusted only a few times per year,the annual energy harvesting is increased by 2.8 times compared with planar solar cells without solar tracking.These results represent a potentially drastic cost reduction in both the module and the balance of system costs compared with heavy,rigid conventional modules and trackers that are subject to wind loading damage and high installation costs.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11725521, and 12035004)the Science and Technology Commission of Shanghai Municipality (Grant No. 20JC1414700)。
文摘The concentrating efficiency of a thermal concentrator can be reflected in the ratio of its interior to exterior temperature gradients,which, however, has an upper limit in existing schemes. Here, we manage to break this upper limit by considering the couplings of thermal conductivities and improve the concentrating efficiency of thermal concentrators. For this purpose, we first discuss a monolayer scheme with an isotropic thermal conductivity, which can break the upper limit but is still restricted by its geometric configuration. To go further, we explore another degree of freedom by considering the monolayer scheme with an anisotropic thermal conductivity or by adding the second shell with an isotropic thermal conductivity, thereby making the concentrating efficiency completely free from the geometric configuration. Nevertheless, apparent negative thermal conductivities are required, and we resort to external heat sources realizing the same effect without violating the second law of thermodynamics. Finite-element simulations are performed to confirm the theoretical predictions, and experimental suggestions are also provided to improve feasibility. These results may have potential applications for thermal camouflage and provide guidance to other diffusive systems such as static magnetic fields and dc current fields for achieving similar behaviors.
基金National Key Research and Development Program of China(2020YFA0710100)the National Natural Science Foundation of China(61731010)+1 种基金the Fundamental Research Funds for the Central Universities(WUT:2021IVA064)the Foundation from Guangxi Key Laboratory of Optoelectronic Information Processing(GD21203).
文摘Solar energy is an inexhaustible renewable energy resource,which is a potential solution to global warming and aids sustainable development.The use of solar-thermal collectors to harness solar energy facilitates low-cost heat storage and can improve the stability of power grids based on renewable energy.In solar-thermal collectors,traditional concentrators,such as parabolic troughs and dishes,are typically used but inevitably require high-precise supports and complex tracking sun systems,which increase the cost of solar-thermal power stations and hinder their further applications.In contrast,planar meta-lenses(so-called metasurface-based concentrators)consisting of two-dimensional nanostructured arrays are allowed to engineer the frequency dispersion and angular dispersion of the incident light through delicately arranging the aperture phase distribution,thereby correcting their inherent aberrations.Accordingly,the novel meta-lenses offer tremendous potentials to effectively capture broadband,wide-angle sunlight without the extra tracking system.This review summarizes the research motivation,design principles,building materials,and large-area fabrication methods of meta-lens for solar energy harvesting in terms of focusing efficiency,operation bandwidth,and angular dependence.In addition,the main challenges and future goals are examined.
