Promising Technology For Application Research Articles

Reactive layered hydroxide membrane for advanced water treatment: Micropollutant degradation and antifouling potential

The effective removal of micropollutants by water treatment technologies remains a significant challenge. Herein, we develop a CoFe layered double hydroxide (CoFeLDH) catalytic membrane for peroxymonosulfate (PMS) activation to achieve efficient micropollutant removal with improved mass transfer rate and reaction kinetics. This study found that the CoFeLDH membrane/PMS system achieved an impressive above 98% degradation of the probe chemical ranitidine at 0.1 mM of PMS including five more micropollutants (Sulfamethoxazole, Ciprofloxacin, Carbamazepine, Acetaminophen and Bisphenol A) at satisfactory level (above 80%). Moreover, significant improvements in water flux and antifouling properties were observed, marking the membrane as a specific advancement in the removal of membrane fouling in water purification technology. The membrane demonstrated consistent degradation efficiency for several micropollutants and across a range of pH (4–9) as well as different anionic environments, thereby showing it suitability for scale-up application. The key role of reactive species such as SO4•–, and O2• − radicals in the degradation process was elucidated. This is followed by the confirmation of the occurrence of redox cycling between Co and Fe, and the presence of CoOH+ that promotes PMS activation. Over the ten cycles, the membrane could be operated with a flux recovery of up to 99.8% and maintained efficient performance over 24 h continuous operation. Finally, the efficiency in degrading micropollutants, coupled with reduced metal leaching, makes the CoFeLDH membrane as a promising technology for application in water treatment.

Electrochemical recovery of lithium from brine by highly stable truncated octahedral LiNi0.05Mn1.95O4

Lithium extraction from salt lakes has become a hot research issue in recent years, and LiMn2O4-based electrochemical lithium extraction is considered to be one of the most promising technologies for application. However, LiMn2O4 limits its further application due to the dissolution of Mn and the Jahn-Teller effect. In this study, a LiNi0.05Mn1.95O4 (LNMO-0.05) lithium-extraction electrode material with truncated octahedral characteristics was prepared. The special crystal surface structure enhanced the diffusion and adsorption rates of Li+, whereas Ni doping effectively suppressed the Jahn-Teller effect, and the two mechanisms synergistically enhanced the lithium extraction performance of LMO. In lithium extraction from East Taijiner brine with an Mg/Li ratio of 46, LNMO-0.05 showed excellent ion selectivity (αMg-Li = 214.08), high lithium extraction capacity (20.99 mg/g) and no significant capacity decay occurred after 10 cycles. These excellent properties make the LNMO-0.05 electrode suitable for industrial electrochemical lithium extraction.

Texture features-based lightweight passive multi-state crowd counting algorithm

Passive crowd counting using channel state information (CSI) is a promising technology for applications in fields such as smart cities and commerce. However, the most existing algorithms can only recognize the total number of people in the monitoring area and cannot simultaneously recognize the number and states of people and ignore the real-time performance of the algorithms. Therefore, they cannot be applied to the scenarios of multi-state crowd counting requiring high real-time performance. To address this issue, a lightweight passive multi-state crowd counting algorithm called TF-LPMCC is proposed. This algorithm constructs CSI amplitude data into amplitude and time–frequency images, extracts texture features using the gray-level co-occurrence matrix (GLCM) and gray-level difference statistic (GLDS) methods, and uses the linear discriminant analysis (LDA) algorithm to count the crowd in multi-states. Experiments show that the TF-LPMCC algorithm not only has low time complexity but also achieves an average recognition accuracy of 98.27% for crowd counting.

Editorial Introduction to the Issue on Advanced Signal Processing for Reconfigurable Intelligent Surface-Aided 6G Networks

The papers in this special issue aim to report on the latest advances in signal processing for reconfigurable intelligent surface (RIS)-aided 6G networks with focus on theoretical development, algorithmic design, and future applications.RIS or intelligent reflecting surface (IRS) technology has been widely regarded as one of the most promising techniques to deal with the blockage issue in millimeter-wave (mmWave) communications. An RIS is a planar surface consisting of an array of nearlypassive reflecting elements, each of which can independently induce an controllable phase shift on the incident signal. By installing RIS on walls or ceilings, a virtual line-of-sight (LoS) link between a mmWave base station (BS) and the users can be established so as to bypass any blockage between them. In addition, RIS is a promising technology for applications in conventional sub-6 GHz communications. Specifically, by judiciously adjusting the phase shifts of the reflecting elements, the reflected signals can be constructively superimposed (even with the direct path if it is available) to enhance the desired signal power or can be cancelled out to mitigate the impact of co-channel interference or signal leakage to eavesdroppers. Since the elements of an RIS reflect the incoming signals without any signal processing operations that require radio-frequency (RF) chains, an RIS has a lower implementation cost than conventional active receivers and transmitters. An RIS can be fabricated with light weight and small-thickness layers, and thus can be readily integrated into the environment.

Dynamic Surface Wrinkles for In Situ Light-Driven Dynamic Gratings.

Dynamic diffraction gratings (DDGs) are considered as one of the most promising technologies for application in smart optical devices because of their in situ dynamic regulation of light propagation on demand; however, it is still a challenge to fabricate dynamic periodic micro/nanostructures due to limited materials and processes. Here, a facile and feasible strategy to construct a near-infrared (NIR) radiation-driven DDG is developed based on a double-sided surface pattern, which is fabricated by dynamic wrinkles and/or soft-imprinted static wrinkles. Poly(dimethylsiloxane) (PDMS) containing carbon nanotubes (CNTs) serves as the substrate, and wrinkles are formed on both sides. The resulting double-sided wrinkle pattern can be used as a DDG to generate various adjustable two-dimensional (2D) diffraction patterns driven by NIR light. Furthermore, with various combinations of wrinkles, we demonstrated a single-sided responsive DDG and a double-sided responsive DDG to realize the evolution of diffraction patterns from 2D to one-dimensional (1D) and 2D to zero-dimensional (0D), respectively. The results provide an alternative for DDGs that will have wide applications in smart display, sensing, and imaging systems.

Exploring AI-healthcare innovation: natural language processing-based patents analysis for technology-driven roadmapping

PurposeThe purposes of this paper are (1) to explore the overall development of AI technologies and applications that have been demonstrated to be fundamentally important in the healthcare industry, and their related commercialized products and (2) to identify technologies with promise as the basis of useful applications and profitable products in the AI-healthcare domain.Design/methodology/approachThis study adopts a technology-driven technology roadmap approach, combined with natural language processing (NLP)-based patents analysis, to identify promising and potentially profitable existing AI technologies and products in the domain of AI healthcare.FindingsRobotics technology exhibits huge potential in surgical and diagnostics applications. Intuitive Surgical Inc., manufacturer of the Da Vinci robotic system and Ion robotic lung-biopsy system, dominates the robotics-assisted surgical and diagnostic fields. Diagnostics and medical imaging are particularly active fields for the application of AI, not only for analysis of CT and MRI scans, but also for image archiving and communications.Originality/valueThis study is a pioneering attempt to clarify the interrelationships of particular promising technologies for application and related products in the AI-healthcare domain. Its findings provide critical information about the patent activities of key incumbent actors, and thus offer important insights into recent and current technological and product developments in the emergent AI-healthcare sector.

Negative thermal-flux phenomenon and regional solar absorbing coating improvement strategy for the next-generation solar power tower

Solar power tower (SPT) is regarded as the most promising technology for applications in concentrating solar power. However, a significant decrease in the solar-thermal conversion efficiency of the tower receiver in the SPT system occurs at high operating temperatures due to the massive radiation heat loss caused. In this work, a detailed heat transfer model of the tower receiver was established, and the negative thermal-flux phenomenon was discovered in the tower receiver based on the verified simulation results. In this context, a novel improvement strategy for regional solar absorbing coating on the tower receiver was proposed to enhance the thermal performance of the tower receiver in the next-generation SPT system. Two kinds of novel tower receivers by changing conventional solar absorbing coating into the silver-based coating (novel receiver I) and black chrome-based coating (novel receiver II) at negative thermal-flux regions were proposed, investigated, and compared with the prototype tower receiver without changes. The overall thermal performance of three kinds of tower receivers was numerically analyzed under different solar irradiances, solar hours throughout the day, and seasons. The results demonstrated that both the novel tower receivers achieved breakthrough enhancements on the thermal performance compared with the prototype receiver, showing great potential for practical application. The negative thermal-flux regions accounted for almost a quarter of the entire receiver surface. The annual average radiation heat losses from negative thermal-flux regions in the novel receivers I and II were effectively reduced by 93.00 and 53.14%. Accordingly, the annual average heat gains and receiver efficiencies were significantly enhanced by 6.54 and 6.03%, respectively.

Enhanced Performance of Pixelated Quantum Dot Light‐Emitting Diodes by Inkjet Printing of Quantum Dot–Polymer Composites

AbstractInkjet printing of colloidal quantum dots (QDs) is considered a promising technology for application in full‐color quantum dot light‐emitting diode (QLED) displays. However, QLEDs that are inkjet printed in a pixel‐defining bank structure generally exhibit a low performance, mainly due to the nonuniformity in its QD morphology. In this study, an enhanced performance of inkjet‐printing‐based pixelated QLEDs is achieved by introducing small amounts of poly(methyl methacrylate) (PMMA) of different molecular weights into QD inks. When this QD–PMMA composite ink is adopted, uniform droplets are formed, originating from contact line depinning during drying. Inside the bank structure, the inkjet‐printed QD–PMMA composite film shows a smooth surface and little pileup at the bank edges. A pixelated QLED with PMMA with a molecular weight of 8 kDa exhibits the highest luminance of 73 360 cd m−2 and an external quantum efficiency of 2.8%, which are remarkably higher than that of the inkjet‐printed QLED subpixels without PMMA. The result is verified through the observation of the drying process and the QLED subpixel shapes under operation. Thus, inkjet‐printed QD–PMMA composite inks can be a promising strategy for future research on pixelated QLEDs for the fabrication process of full‐color QLED displays.

Mitochondrial Medicine: Genetic Underpinnings and Disease Modeling Using Induced Pluripotent Stem Cell Technology.

Mitochondrial medicine is an exciting and rapidly evolving field. While the mitochondrial genome is small and differs from the nuclear genome in that it is circular and free of histones, it has been implicated in neurodegenerative diseases, type 2 diabetes, aging and cardiovascular disorders. Currently, there is a lack of efficient treatments for mitochondrial diseases. This has promoted the need for developing an appropriate platform to investigate and target the mitochondrial genome. However, developing these therapeutics requires a model system that enables rapid and effective studying of potential candidate therapeutics. In the past decade, induced pluripotent stem cells (iPSCs) have become a promising technology for applications in basic science and clinical trials, and have the potential to be transformative for mitochondrial drug development. Engineered iPSC-derived cardiomyocytes (iPSC-CM) offer a unique tool to model mitochondrial disorders. Additionally, these cellular models enable the discovery and testing of novel therapeutics and their impact on pathogenic mtDNA variants and dysfunctional mitochondria. Herein, we review recent advances in iPSC-CM models focused on mitochondrial dysfunction often causing cardiovascular diseases. The importance of mitochondrial disease systems biology coupled with genetically encoded NAD+/NADH sensors is addressed toward developing an in vitro translational approach to establish effective therapies.

Hydroxyl and sulfate radical advanced oxidation processes: Application to an agro-industrial wastewater

In this study, the effectiveness of a UV-A LEDs system, transition metal activators (Fe and Co) and different oxidants (hydrogen peroxide, H 2 O 2 ; peroxymonosulfate, PMS and persulfate, PS) were evaluated in the degradation of an elderberry wastewater. Several oxidation processes can be applied using the pointed out oxidants, UV radiation and transition metals, which can be classified as hydroxyl radical advanced oxidation processes (HR-AOPs) and sulfate radical advanced oxidation processes (SR-AOPS). The initial trials achieved 99% of TOC removal in UV-A LED/H 2 O 2 (with multi-step additions)/Fe 2＋ and with PMS (single addition)/Co 2 + processes, which were afterwards optimized for metal activator dosage. The UV-A LED/H 2 O 2 (multi-step addition)/Fe 2＋ process demonstrated a lower TOC removal when the Fe 2＋ concentration was reduced (50 mg/L – 99% removal and 25 mg/L only 75%). On the other hand, PMS (single step addition)/Co 2 + process still presented 99% of TOC removal, even when the Co 2 + concentration decreased from 50 to 25 mg/L. Bearing in mind this performance, the Co 2 + concentration was optimized achieving the following optimal operational conditions: [PMS] = 45 mM; [Co 2 + ] = 7.5 mg/L; pH = 3 and reaction time = 120 min. In addition, PMS/Co 2 + process allows to increase the biodegradability (BOD 5 /COD) ratio from 0.30 to 0.53 mg O 2 /L of treat water. Hence, the PMS/Co 2 + oxidation process can be considered a promising technology for application in real scale agro-food wastewater treatment plants, since it shows a very good compromise in terms of TOC removal and reduced carbon footprint. • Hydroxyl and sulfate radicals-based AOPs in elderberry wastewater treatment. • Radical generation by UV-A LEDs, transition metals and oxidants (H 2 O 2 , PMS and PS). • Influence of single and multiple additions of oxidants. • UV-A LED/H 2 O 2 (multi-additions)/Fe(II) and PMS(single addition)/Co(II) reach 99% TOC removal. • PMS/Co(II) optimal conditions: [PMS] = 45 mM; [Co(II)] = 7.5 mg/L; pH = 3 and 120 min.

A High-Energy-Density and Long-Life Chalcogenide-Iodide Redox Flow Battery

Redox flow batteries (RFBs) are promising technologies for application in both grid-scale power station and electric vehicles owing to their flexible architecture decoupling power and energy1, 2. The development of aqueous RFBs has been strongly hindered by low energy density, limited cell voltage and rapid capacity fading, which largely can be attributed to the poor solubility of electroactive species, small voltage window of water and limited ion selectivity capability of membrane1. Chalcogenide has been reported to have high solubility in nonaqueous environment with high charge/discharge reversibility, which makes it a promising anolyte candidate for aqueous RFBs3-5. However, it is found that these sulfur-based RFBs have been challenged by their poor cycle life and rate capability, owing to the strong shuttle phenomenon and slow kinetics of polysulfide reaction3, 5. It is critical to manipulate the competition between diffusion/crossover and the rate of electrochemical reaction of soluble active species in order to improve cycle life of RFBs. In this work, we exploited a composite-based ion-exchange membrane for chalcogenide-iodide RFBs. We evaluated the effectiveness of various membrane compositions and will discuss the role of each component in the membrane toward long-life operation. We applied UV-vis spectroscopy to probe the active reaction species involved in the RFB operation. In addition, we will discuss the use of complexing agent for polysulfide species to increase the energy density (molar electron number per molecule) and energy efficiency (higher reaction kinetics) of the chalcogenide-iodide RFBs. Acknowledgement: This work was fully supported by a grant from the Research Grant Council of the Hong Kong Special Administrative Region, China under NSFC/RGC Joint Research Scheme 2018/19 Project No. N_CUHK435/18. Reference: W. Wang, Q. Luo, B. Li, X. Wei, L. Li and Z. Yang, Adv. Funct. Mater., 23, 970-986 (2013).F. Pan and Q. Wang, Molecules, 20, 20499-20517 (2015).S. Yun, S. H. Park, J. S. Yeon, J. Park, M. Jana, J. Suk and H. S. Park, Adv. Funct. Mater., 1707593 (2018).N. Li, Z. Weng, Y. Wang, F. Li, H.-M. Cheng and H. Zhou, Energy Environ. Sci., 7, 3307-3312 (2014).Z. Li, G. Weng, Q. Zou, G. Cong and Y.-C. Lu, Nano energy, 30, 283-292 (2016).

Nanoplasmonic optical antennas for life sciences and medicine

Surface plasmons — light-induced oscillations of electrons at the surface of nanoplasmonic metallic nanoparticles or nanostructures — can be used in a wide range of applications. Such nanoplasmonic optical antennas can be interfaced with biological systems to answer diverse questions in life sciences and to solve problems in translational medicine. In particular, nanoplasmonics provide insight and solutions for intracellular exploration, gene delivery and regulation, and rapid precision molecular diagnostics. In this Review, we examine the development of nanoplasmonic optical antennas for in vitro and in vivo applications. We evaluate the use of optical nanoplasmonic antennas for the optical detection of mRNA in living cells and for in vivo molecular imaging. We also discuss nanoplasmonic optical antennas for in vivo gene delivery and the optical control of gene circuits. Finally, we highlight the use of nanoplasmonic-based molecular diagnostic systems for ultrafast precision medicine. Nanoplasmonics have emerged as a promising technology for applications in life sciences and medicine. In this Review, we discuss the application of nanoplasmonic optical antennas for in vivo intracellular exploration, photonic gene delivery and regulation, and in vitro molecular diagnostics.

Diamond detectors for high energy physics experiments

Beam test results of the radiation tolerance study of chemical vapour deposition (CVD) diamond against different particle species and energies is presented. We also present beam test results on the independence of signal size on incident particle rate in charged particle detectors based on un-irradiated and irradiated poly-crystalline CVD diamond over a range of particle fluxes from 2 kHz/cm2 to 10 MHz/cm2. The pulse height of the sensors was measured with readout electronics with a peaking time of 6 ns. In addition functionality of poly-crystalline CVD diamond 3D devices was demonstrated in beam tests and 3D diamond detectors are shown to be a promising technology for applications in future high luminosity experiments.

Simultaneous wireless information and power transfer for AF relaying nanonetworks in the Terahertz Band

A nanonetwork is comprised of nanoscale sensors and communicating devices facilitating communication at the nanoscale, which is a promising technology for application in health applications such as intra-body health monitoring and drug delivery. However, the communication performance within a nanonetwork is substantially limited by the energy loss as the Electromagnetic (EM) wave propagates along the channel. Energy harvesting for nanosensor networks can provide a way to overcome the energy bottleneck without considering the lifetime of batteries. Moreover, relaying protocols for nanoscale communications have been proposed to improve the communication performance and extend the transmission distances among nanosensors within nanonetworks. The combination of energy harvesting and a relaying protocol provides an emerging solution not only to overcome the aforementioned energy issues but also enhance the system performance. Therefore, in this paper, simultaneous wireless information and power transfer nanonetworks in the Terahertz (THz) Band (0.1-10 THz) is proposed. An amplify and forward (AF) relaying nanonetwork in this band is investigated, where the relay harvests energy from the received THz signal which is then consumed to forward the information to the destination. Performance based on both time-switching and power-splitting protocols is analyzed. The numerical results show the optimal power-splitting ratio and time switching ratio that achieves the maximum throughput at the destination as well as the impact of transmission distance on system performance. It is seen that the power-splitting protocol gives greater throughput than that of the time-switching protocol.

Treatment of winery wastewater by sulphate radicals: HSO5−/transition metal/UV-A LEDs

In this study, the effectiveness of the HSO5−/Mn+/UV process on the treatment of winery wastewater (WW) was investigated. The optimal operating conditions were determined: [HSO5−]=2.5mM; [M2(SO4)n]=1.0mM; pH=6.5 and reaction temperature=323K. Under the given conditions, 51%, 42% and 35% of COD removal was achieved using respectively Fe(II), Co(II) and Cu(II) as catalysts. Different UV sources were tested with the previously selected optimal conditions in order to increase the treatment efficiency. The highest COD removal (82%) was achieved using a UV-A LEDs system (70W/m2). These conditions were also promising for the treatment of WW with COD concentrations of 5000mg O2/L, reaching 79% and 64% of COD and TOC removal, respectively, after 180min of treatment. At 323K, the most effective treatment was obtained when Co(II) was used as catalyst (79% and 64% of COD and TOC removal), while at ambient temperature (293K) the highest COD (65%) and TOC (52%) removals were obtained with Fe(II) catalyst. Moreover, it was demonstrated that the use of HSO5−/Mn+ in several consecutive doses was more efficient than adding the reagents as a single dose at the beginning of the reaction. A comparison between the performance of the HSO5−/Fe(II)/UV-A LED process and the conventional photo-Fenton demonstrated important advantages associated with the HSO5−/Fe(II)/UV-A LED process, including the absence of the costly pH adjustment and of the hydroxide ferric sludge which characterise the photo-Fenton treatment process. The HSO5−/Mn+/UV-A LED process demonstrates a high COD and TOC removal efficiency, and it can be considered a promising technology for application in real scale agro-food wastewater treatment plants.

Quantum dots in the GaAs/AlxGa1−xAs core-shell nanowires: Statistical occurrence as a function of the shell thickness

Quantum dots (QDs) embedded in nanowires represent one of the most promising technologies for applications in quantum photonics. Self-assembled bottom-up fabrication is attractive to overcome the technological challenges involved in a top-down approach, but it needs post-growth investigations in order to understand the self-organization process. We investigate the QD formation by self-segregation in AlxGa1−xAs shells as a function of thickness and cross-section morphology. By analysing light emission from several hundreds of emitters, we find that there is a certain thickness threshold for the observation of the QDs. The threshold becomes smaller if a thin AlAs layer is pre-deposited between the GaAs nanowire core and the AlxGa1−xAs shell. Our results evidence the development of the quantum emitters during the shell growth and provide more guidance for their use in quantum photonics.

Ultrasound technology and molecular sieves improve the thermodynamically controlled esterification of butyric acid mediated by immobilized lipase from Rhizomucor miehei

In this research, the effects of ultrasound stirring and the addition of molecular sieves on esterification reactions between butyric acid and several alcohols catalyzed by immobilized lipase from Rhizomucor miehei (Lipozyme RM-IM) were studied. Among the tested alcohols, 1-propanol and isobutanol allowed the highest activities, whereas Lipozyme RM-IM showed poor activities for esterification using secondary and tertiary alcohols. Different solvents were also tested and n-hexane was selected because of its reaction effects, besides being cheaper, available at low boiling point, and ease of recovery. Using the preselected alcohol and solvent, other reaction parameters (butyric acid concentration, temperature, substrate molar rate, and biocatalyst content) were studied to optimize the reaction conditions. Optimal conditions were acid concentration, 0.7 M; substrate molar ratio, 1 : 1 alcohol–acid; temperature 45 °C; biocatalyst content, 14% (by substrate mass). Under these conditions, it was possible to obtain a yield of 86% of butyl butyrate in 2.5 h. When molecular sieves (90 mg mmol−1 butytic acid) were added to the reaction, the observed yield increased to 96%. The biocatalyst was used in 5 successive reaction cycles keeping 100% of its initial activity. The overall process productivity was improved 2-fold when compared to the traditional mechanical agitation, showing that ultrasound is a promising technology for application in biocatalysis.

Self-assembly of single “square” quantum rings in gold-free GaAs nanowires

Single nanostructures embedded within nanowires (NWs) represent one of the most promising technologies for applications in quantum photonics. However, fabrication imperfections and etching-induced defects are inevitable for top-down fabrications, whereas self-assembly bottom-up approaches cannot avoid the difficulties of its stochastic nature and are limited to restricted heterogeneous material systems. Here we demonstrate the versatile self-assembly of single "square" quantum rings (QR) on the sidewalls of gold-free GaAs NWs for the first time. By tuning the deposition temperature, As overpressure and amount of gallium-droplets, we were able to control the density and morphology of the structure, yielding novel single quantum dots, QR, coupled QRs, and nano-antidots. A proposed model based on a strain-driven, transport-dependent nucleation of gallium droplets at high temperature accounts for the formation mechanism of these structures. We achieved a single-QR-in-NW structure, of which the optical properties were analyzed using micro-photoluminescence at 10 K and a spatially resolved cathodoluminescence technique at 77 K. The spectra show sharp discrete peaks; of these peaks, the narrowest linewidth (separation) was 578 μeV (1-3 meV), reflecting the quantized nature of the ring-type electronic states.

Self-assembled quantum dots in a nanowire system for quantum photonics

Quantum dots embedded within nanowires represent one of the most promising technologies for applications in quantum photonics. Whereas the top-down fabrication of such structures remains a technological challenge, their bottom-up fabrication through self-assembly is a potentially more powerful strategy. However, present approaches often yield quantum dots with large optical linewidths, making reproducibility of their physical properties difficult. We present a versatile quantum-dot-in-nanowire system that reproducibly self-assembles in core-shell GaAs/AlGaAs nanowires. The quantum dots form at the apex of a GaAs/AlGaAs interface, are highly stable, and can be positioned with nanometre precision relative to the nanowire centre. Unusually, their emission is blue-shifted relative to the lowest energy continuum states of the GaAs core. Large-scale electronic structure calculations show that the origin of the optical transitions lies in quantum confinement due to Al-rich barriers. By emitting in the red and self-assembling on silicon substrates, these quantum dots could therefore become building blocks for solid-state lighting devices and third-generation solar cells.

A comparison of the kinetics of mango drying in open-air, solar, and forced-air dryers

Mangoes are under-utilized fruits that grow naturally in many sub-Saharan African countries. At the present time most mangoes are sold fresh in local markets. There is little done to preserve them for use during the off-season. Drying is one way in which the economic potential of mangoes could be exploited. This study was undertaken to investigate and compare the kinetics of mango drying using three basic drying methods: open-air drying on wire mesh racks; solar drying in a prototype dryer equipped with solar-powered exhaust fans; and forced-air drying in an Armfield Model UOP8 laboratory-scale tray dryer. Results could then be used to determine appropriate drying techniques for mango processing in sub-Saharan Africa on both local and commercial scales. Of these methods, forced air drying was found to provide the best overall results, based on water removal rates and general control over the drying process. Solar drying, while viewed as a promising technology for application in developing countries, was considerably slower than forced- air drying and is severely restricted by climatic conditions. A similar situation was observed for open-air drying, which was the slowest drying method of the three. Based upon mathematical models developed for each drying method, 11.6 hours was predicted as being required for mangoes in the forced-air dryer to a final moisture content of 10% (wet basis). Sixteen (16) hours and 24 hours of exposure to appropriate drying conditions were predicted as being required for solar drying and open-air drying, respectively. This could take three or four days to achieve under actual operating conditions. These times were supported by experimentally determined values. The impact of air temperature and linear air velocity on the drying kinetics of sliced mangoes were also investigated using the forced-air dryer. A linear velocity of 0.5 m/s was found to be sufficient for satisfactory drying of the mango slices when combined with an air temperature in the range of 50ΕC to 60ΕC. It is recommended that forced-air drying be utilized whenever possible for the drying of mango slices for both food safety and food quality reasons.