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Converting plastic waste into valuable products (syngas) is a promising approach to achieve sustainable cities and communities. Here, we propose for the first time to convert plastic waste into syngas via the Fe

To investigate and optimize the use of methyl cellulose in the fabrication of three-dimensional (3D) printed drug-loaded hydrogel wound dressings for the treatment of burns.The effects of incorporating various salts on the properties of methyl cellulose, especially the gelation temperature was investigated for methyl cellulose to undergo gelation at skin temperature (i.e., 31.7°C). The optimized methyl cellulose and salt compositions were then loaded with various drugs beneficial for the treatment of burns. Printability and cumulative release profiles for selected drugs were then obtained, which were then fitted to common release kinetic models. Computational Fluid Dynamics (CFD) simulation was also explored to investigate the relationship between printing parameters and the hydrogel filament produced during extrusion.The printed hydrogels had moderate dimensional integrity, were found to be stable for up to 2 weeks and demonstrated good swelling properties. In vitro drug release studies of various drugs showed that the hydrogel was able to release various drugs within 6 h and release profiles were fitted to common in vitro drug release models, such as the Korsmeyer Peppas model and the Weibull model. While there were deviations from the actual printing process, CFD simulation was able to predict the shape of the printed structure and showed fair accuracy in determining the mass flow rate and line width of extruded hydrogels.Methyl cellulose hydrogels with optimized salt composition demonstrated suitable properties for a wound dressing application, revealing its potential to be used for in situ wound dressing applications.

The oxy-fuel co-firing of solid fuels (such as coal, biomass, and solid waste) in fluidized beds is one of the most promising technologies for the industrial application of CO2 capture and waste disposal. However, both the practical experimentation and numerical simulations for elucidating co-firing in an oxy-fuel fluidized bed are still limited. In this study, a multiphase particle-in-cell scheme based on a 3D Eulerian–Lagrangian model was further developed following our previous research on oxy-fuel co-firing in a micro fluidized bed (Powder Technol. 2020, 373, 522–534). The refined JL 4-step mechanism for the CO-CO2 homogeneous reactions, the heterogeneous reactions of char oxidation and gasification, the heterogeneous reactions of NO and N2O formation from char-N, and the self-desulfurization effect were comprehensively considered. The improvement of the models was verified through the continuous operation of 10 kWth oxy-fuel fluidized bed tests (Fuel 2021,286,119,312; Energy Fuels, 2020, 34, 7373–7387), and the effects of the biomass blending ratio (Mb) on co-firing characteristics were discussed. It was found that the improvements could enhance the adaptability of the models to the oxy-fuel atmosphere, and the accurate prediction of NO, N2O, SO2. With an increase in Mb, the main reaction zone expanded or moved up along the riser height, and the volume of the high-temperature area increased, which promoted the burnout of particles and CO2 emission when Mb is 50%. The high volatility of biomass increased O2 consumption and CO concentration at the upper part of the riser, reduced N2O formation, and had a significant impact on NO reduction. The low sulfur content and high Ca/S ratio of the biomass considerably reduced the SO2 concentration. The simulation results also provided helpful information for the design and operation control of oxy-fuel co-firing of coal and biomass in a fluidized bed, such as the oxidant supply in different areas and grades, appropriate increase in the riser height, and reasonable adoption of Mb.

Particle-laden turbulent flow under saturated electrostatic field in 90-degree bend pipe at Reb = 58000 is investigated using one-way coupled Large Eddy Simulation (LES) with a Lagrangian particle tracking technique. Drag, lift, buoyancy, gravity, and electrostatic force are considered. Three particle sizes (dp = 5, 10, 50 μm, St = 5.47, 21.91, 547) are considered. The results show that particle concentration is higher in outer bend than that in inner bend and the concentration increases with particle size. At the stagnation point of Dean vortices near the inner arc of bend, particle concentration is significantly increased under the synergy effect of electrostatics and secondary flow. In addition, particles trapped in the viscous layer are difficult to resuspend under electrostatic effect. Particle concentration near the wall under the presence of electrostatics is larger than that under the absence of electrostatics. However, at the bend, particle concentration in the core region under the presence of electrostatics is lower than that in the absence of electrostatics. For particle behavior, drag force plays the most important role in the core region while electrostatic force dominates the near wall region and causes particles to accumulate there.

Isothermal chemical conversion of biomass pellets under the atmospheres of Ar, CO2 and O2 were conducted in this study to explore the effects of atmosphere and temperature on the gaseous releasing process and kinetics, and the structure of the solid char/ash products. Results showed that the gas production was promoted while the solid yield was decreased with the raising temperature. The CO2 reaction with char during gasification process mainly happened after 800 °C that the CO formation lasted for a longer time than pyrolysis. The surface area of char under CO2 atmosphere was increased to 215.57 m2/g with the increased temperature to 800 °C, but it was sharply reduced to 5.10 m2/g when the temperature further raising to 900 °C due to the destroyed carbon skeleton. The CO2 formation was largely promoted with a low activation energy of 11.98 kJ/mol during O2 oxidation process. Compared with the crystal structure of solid residues obtained under Ar and CO2 atmospheres, O2 oxidation process resulted in more complex crystal peaks with the main compositions of SiO2, K2SO4, and CaO. This study should be helpful to further understand the thermal conversion of biomass in a complex reaction atmosphere.

The poor translation of nanomedicines from bench to bedside can be attributed to (i) lack of a delivery system with precise drug compositions with no batch-to-batch variations, (ii) off-target or undesirable release of payload, and (iii) lack of a method to monitor the fate of the specific drug of interest, which often has to be modified with a fluorescent tag or replaced with a model drug which can be tracked. To overcome these translation hurdles, we developed dual responsive organelle targeted nanoreactors (DRONEs) with precise drug composition, site specific payload release and which enable accurate in-vivo monitoring. DRONEs consist of a polyprodrug inner core composed of a dual responsive backbone containing a photosensitizer (Protoporphyrin IX) grafted with functionalized polyethylene glycol (PEG) outer shell to prolong blood circulation and a tumour homing pro-apoptotic peptide (CGKRK

Particle behavior in a turbulent circular-sectioned 90° bend under electrostatic field at three air flow rates (1600 L/min, 1100 L/min and 950 L/min, the corresponding bulk Reynolds numbers are 58,000, 40,000, 34,000) is simulated by a Large Eddy Simulation-Lagrangian particle tracking technique (LES-LPT) method coupled with electrostatic field model by Coulomb’s law. This numerical simulation is dedicated to study the electrostatic effect on particle behavior and erosion occurred in the dilute particle-laden bend flow. Forces considered acting on particles includes drag, lift, gravity and electrostatic force. Results obtained for the fluid phase are in good agreement with experimental and numerical data. Predictions show that electrostatic field does affect the particle motion in the pipe bend. At higher air flow rate with higher electrostatics at the inner arc the increasement of impact angle is lower than that at lower flow rate with lower electrostatics. The same conclusion can be found at the outer arc. In addition, electrostatic effect does increase particle-wall impact velocity while such trend decreases with flow rate. Erosion rate increases with increasing air flow rate, which is independent of electrostatics. However, given the same flow rate, the electrostatics reduces the occurrence of erosion at the bend. The erosion rate under electrostatic effect is found to approach that without electrostatics as the flow rate increases. Therefore, the effect of electrostatics on erosion decreases with the air flow rate.

This study presents the effect of bioaugmentation of thermophilic anaerobic digestion of food waste with Methanosarcina thermophila grown on a wood-derived biochar. Two different supplementation regimes were tested, namely a single bioaugmentation (SBABC) in which 10% v/v of the microbes grown on biochar (1 g/L) is added at setup of the reactors, versus a routine bioaugmentation (RBABC) wherein the same amount of supplements were added over 10 feeding cycles. The optimally performing 'R' and 'S' reactors had increased methane yields by 37% and 32% over their respective controls while reactors SBABC 2 and 3 produced 21.89% and 56.09% higher average methane yield than RBABC 2 and 3, respectively. It appears that a single dose bioaugmentation is advantageous for improving AD as analysed in terms of average methane yield and VFA production. This study provides the basis for understanding how biochar and bioaugmentation can be used for engineering sustainable pilot-scale AD processes.

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Singapore’s first multi-source high-flux solar simulator (HFSS) that comprises an array of seven 4-kWe xenon short-arc lamps close-coupled with ellipsoidal reflectors is designed, constructed, and characterized. An indirect mapping system that consists of a water-cooled Lambertian target, a CMOS camera, and a heat-flux gauge is adopted herein to experimentally characterize the performance of the developed HFSS. A calibration constant of 192.8 ± 9.6 kW m−2 (GS µs−1)–1 is determined and used to transform the raw-flux maps with grayscale values to the absolute-flux maps. Utilizing a series of flexible and precise adjusters, the variability of ± 1 mm in the x- and y-directions of the peak flux points of the radiation modules is measured. A peak flux of 7740 kW m−2 is measured for the sum of all 7 radiation modules. Average radiative fluxes of 4191 kW m−2 and 2933 kW m−2 can be observed from circular target areas of O40 mm and O60 mm, respectively, associated with promising electricity-to-target transfer efficiencies of 18.8% and 29.6%. A Monte Carlo ray-tracing (MCRT) model is calibrated by the experimental data. Based on the minimum root-mean-standard deviation between the measured and simulated results of the radiative power on the target, the optimal parameters of the MCRT model include the arc radius of 3.4 mm and the reflector surface error of 1.1 mrad.

A CO2 -mediated hydrogen storage energy cycle is a promising way to implement a hydrogen economy, but the exploration of efficient catalysts to achieve this process remains challenging. Herein, sub-nanometer Pd-Mn clusters were encaged within silicalite-1 (S-1) zeolites by a ligand-protected method under direct hydrothermal conditions. The obtained zeolite-encaged metallic nanocatalysts exhibited extraordinary catalytic activity and durability in both CO2 hydrogenation into formate and formic acid (FA) dehydrogenation back to CO2 and hydrogen. Thanks to the formation of ultrasmall metal clusters and the synergic effect of bimetallic components, the PdMn0.6 @S-1 catalyst afforded a formate generation rate of 2151 molformate molPd-1 h-1 at 353 K, and an initial turnover frequency of 6860 mol H2 molPd-1 h-1 for CO-free FA decomposition at 333 K without any additive. Both values represent the top levels among state-of-the-art heterogeneous catalysts under similar conditions. This work demonstrates that zeolite-encaged metallic catalysts hold great promise to realize CO2 -mediated hydrogen energy cycles in the future that feature fast charge and release kinetics.

In this work, the pressure wave propagation in the vertical and horizontal directions has been studied using a self-designed clapboard-type internally circulating fluidized bed. The effects of flow regimes and solid mixture on the pressure wave propagation characteristics were analyzed in terms of time-averaged pressure, standard deviation, power spectral density, dominant frequency, propagation time delay, and attenuation. The superficial velocity ratio had a remarkable effect on the pressure wave propagation time delay in the vertical direction but had less influence on the pressure wave propagation in the horizontal direction. The particle circulation provided an extra resistance force to the horizontal pressure wave propagation and resulted in an increase in the pressure wave decay factor in the horizontal direction. The addition of glass beads and salt greatly increased the time delay and decay factor both in vertical and horizontal directions. The addition of 15% corn powder (Geldart-C group) reduced the propagation time delay but increased the decay factor.

As global warming and climate change become perceived as significant, the release of greenhouse gases (GHGs) stored in the earth's polar regions is considered a matter of concern. Here, we focused on exploiting GHGs to address potential global warming challenges in the north polar regions. In particular, we used CO2 as a soft oxidant to recover energy as syngas (CO and H2) and to produce biochars from pyrolysis of peat moss. CO2 expedited homogeneous reaction with volatile matters from peat moss pyrolysis, and the mechanistic CO2 role resulted in the conversion of CO2 and peat moss to CO at ≥530 °C. Steel slag waste was then used as an ex situ catalyst to increase reaction kinetics, addressing the issue of the role of CO2 being limited to ≥530 °C, with the result where substantial H2 and CO formation was achieved at a milder temperature. The porosity of biochars, a solid peat moss pyrolysis product, was modified in the presence of CO2, with a significant improvement in CO2 adsorption capacity compared to those achieved by N2 pyrolysis. Therefore, CO2 has the potential to serve as an initial feedstock in sustainable biomass-to-energy applications and biochar production, mitigating atmospheric carbon concentrations.

The flow dynamics of binary particle mixtures in the fluidized bed needs to be monitored in order to optimize the related industrial processes. In this paper, electrostatic sensing and high-speed imaging are applied to measure the velocities of polyethylene and sand particles in the binary particle mixtures in fluidization. Experimental studies were conducted on a lab-scale cold circulating fluidized bed. Correlation function between electrostatic signals from upstream and downstream electrodes placed along the riser shows two peaks that represent transit times for the two types of particles. To verify the above results, high-speed imaging was adopted to capture the flow images of particle mixtures. Particle Image Velocimetry and Particle Tracking Velocimetry algorithms were utilized to process the resulted images in order to measure the velocities of polyethylene and sand particles. The reasons for two-peak correlation functions are illustrated based on the frequency spectrums of the mono-solid-phase electrostatic signals and the velocity difference between polyethylene and sand particles. Finally, comparisons on the velocities obtained from electrostatic sensing and high-speed imaging demonstrate the electrostatic sensor can roughly estimate the particle velocity of binary particle mixtures in the near wall region of the circulating fluidized bed.

Pneumatic conveying experiments involving monodisperse and binary-size mixtures of glass beads with charges in the range of −10 to 10 nC have been carried out. The mass loss method was adopted, with the minimum pickup velocity (Upu) determined as the minimum velocity at which entrainment occurred. Similar to previous studies on minimum fluidization velocity, the Upu increased with particle initial charge for the positively charged particles (0–10 nC). Surprisingly, however, negatively charged particles exhibited an opposite trend such that the Upu decreased with charge magnitude. Therefore, for the particle initial charge range investigated (−10 to 10 nC), Upu increased monotonically with particle initial charge, and the correlations available (Kalman et al., 2005; Tay et al., 2012) mis-predicted Upu by up to 10 % for monodisperse systems and up to 40 % of binary-size systems. This underscores the necessity to account for particle initial charge in such correlations, particularly for polydisperse particle systems. National Research Foundation (NRF) The authors thank the financial support from the National Research Foundation(NRF), Prime Minister’s Office, Singapore, under its Campus for Research Excellence and Technological Enterprise (CREATE) program, and also the 2nd Intra-CREATE Seed Collaboration Grant (NRF2017-ITS002-013)

Granule electrostatics is widely found in most granule engineering areas. However, the working mechanism has never been fully understood due to its sensitivity to working conditions, such as granule geometrical shape (including length-ratio and front-facing angle), contact area, granule material, relative humidity, sliding velocity, sliding orientation, normal stress and so on. In this work, single granules were chosen to slide along a metal plate and the electrostatics charge generated were measured. The working factors above have been considered for two materials, i.e. PVC and coal. Regarding granule shape, it is found that granules with larger length-ratio tend to produce more electrostatics as well as the slender or sharper granules. Triangular granules generate more electrostatics than trapezoidal granules. In addition, electrostatics charge generation increases with decreasing granule front-facing angle and charges tend to gather at the granule tip. Regarding granule material, it is found that coal granule tends to generate more electrostatics in comparison with PVC granule. The sequence of the relative work function for the three materials used in this work from high to low is given as PVC, stainless steel and coal. Regarding surrounding factors, it is found that electrostatics increases with granule contact area and such trend increases with decreasing relative humidity. Electrostatics generated increases with decreasing relative humidity and sliding velocity. Granule sliding orientation does affect electrostatics. In this work, granules sliding with smaller front-facing angle as well as shorter side tend to generate more electrostatics. Electrostatics increases with normal stress.

Intelligent nanomedicines integrated with stimuli-responsive components enable on-demand customizable treatment options which would improve therapeutic outcome and reduce systemic toxicity. In this work, we explore the synergistic therapeutic potential of photodynamic therapy and immunometabolic modulation to achieve tumour regression and to trigger an adaptive immunity to prevent tumour recurrence. The therapeutic potential of the fabricated Bioengineered Immunomodulatory Organelle targeted Nanozymes (BIONs) was tested on 3D printed mini-brains which could effectively recapitulate the biologically relevant interactions between glioblastoma cells and macrophages. In the presence of glioblastoma organotypic brain slices, activated BIONs upregulated the cell surface expression of CD86, a costimulatory molecule and CD83, maturation marker, on monocyte derived dendritic cells, suggesting its ability to elicit a strong immune response. Furthermore, the antigen pulsed dendritic cells by chemotaxis and transendothelial migration readily relocate into the draining lymph node where they present the antigenic cargo to enable the proliferation of T lymphocytes. The stealth and tunable catalytic activity of BIONs prevent ROS mediated diseases such as acute kidney injury by providing environment dependent protection without compromising on its promising anti-cancer activity.

In this paper, a dynamic biomass gasification model was developed based on the hybrid peripheral fragmentation and shrinking-core (HPFS) model. To improve the accuracy of syngas generation transient prediction, the chemical kinetic model was trained using global surrogate optimization techniques. The pre-exponential factors of kinetic reactions are calibrated under non-catalytic conditions, employing experimental transient data of syngas generation rate and compositions under different temperatures and gasifying agents. The DYCORS and GOMORS were employed as the numerical solvers for finding the global optimum solution of the pre-exponential factors. The calibrated kinetic models based on both single-objective and multi-objective approaches have been validated by experimental data in four different biomass gasification scenarios. The calibrated kinetic model shows an over 95% decrease in terms of integrated squared error (ISE)-based model mismatch when compared to the original kinetic model.

To help minimize the negative impact of chemical fertilizers on the environment, recycle nitrogen and phosphorus nutrients of anaerobic digestate and reduce loss of nutrients via leaching, an eco-friendly slow-release fertilizer was prepared through recovery of nitrogen and phosphorus nutrition from digestate using superabsorbent fibers extracted from soybean curd residue as an adsorbent. The preparation method was proposed, and the fiber composite-based adsorbent was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscope (SEM) techniques. The successful incorporation of N and P into the fiber composite-based adsorbent via adsorption was confirmed by results of these analyses. The prepared fertilizer showed a relatively high N content (3.65 wt%) and a limited P content (0.14 wt%). Also, the swelling capacity as well as water retention capability of the obtained fiber composite-based adsorbent were evaluated. The release behavior of N and P from impregnated fiber composites was examined and was found to be partially in good accordance with the standard of the Committee of European Normalization, showing good slow-release and water-retention properties. Furthermore, in order to assess the fertilizer quality of the prepared materials, the effects of different fertilizers (commercially available fertilizer and prepared slow-release fertilizer) on tomato plant growth and soil microbial communities were investigated. The obtained results demonstrated the potential of fiber composite-based slow-release fertilizer system for recycling N and P nutrition from digestate, improving the effectiveness of fertilizer as well as protecting the environment.

Granules are widely used in solid processing including chemical, mining, energy, environment, food, pharmaceutical industries. As granules are transported in pipelines, electrostatics are to be generated due to granule-wall interactions. In this work, granular surface roughness was particularly investigated for the effect on electrostatics generation for three materials including coal, woodchip and biochar for better understanding of their respective performance in well-designed granule sliding tests. In addition, other factors including granule contact area, granule shape, relative humidity as well as their integrated effects with granule surface roughness on electrostatics were considered. It was found that the electrostatics increased with larger contact area as well as decreasing humidity. In addition, triangle granules were observed to generate more electrostatic charges than rectangle granules such that granule shape was important in determining electrostatics generation. Meanwhile, it was also found that electrostatics generated first increased with granule roughness but decreased after reaching a maximum point, which was independent of granule material. In this work, the electrostatics generated by woodchip granules was obviously higher than that by biochar granules. In addition, other factors such as granule shape, surface roughness for biochar granules were showed to have less effect on electrostatics generation than that for woodchip granules.

The solar powered cooling system based on desiccant coated heat exchanger (DCHE) is an alternative to traditional vapor compression cooling system (VCCS) due to its energy-saving and eco-friendliness. To obtain improved performance, high-porosity Metal-Organic Framework (MOF) is introduced as desiccant. In our study, Cu-BTC (HKUST-1) was fabricated and certified with high purity and good crystallization by X-ray diffraction (XRD). N2 isotherm adsorption-desorption properties of MOF were investigated. Results show that MOF has co-existence of micropores and mesopores with relatively large specific surface area and pore volume. Water vapor isotherm adsorption of MOF and type B silica gel (SGB) was conducted. Isotherms indicate that moisture uptake of MOF is higher than that of SGB at low relative humidity. A dynamic mathematical model of this system was established. The solar performance was evaluated firstly. Results suggest that solar collector can provide 52.5–80.4 °C hot water from 9:00 to 19:00. Then the simulation was conducted under American Air-conditioning and Refrigeration Institute (ARI) summer and Shanghai August conditions. Results exhibit that MOF coated heat exchanger (MCHE) has more significant enhancement of dehumidification performance than SGB coated heat exchanger (SCHE) with increased regeneration temperature and MCHE is more suitable for application under ARI summer condition.

A novel biomass gasification-based combined cooling, heat and power (CCHP) system, which is composed of a gas-fueled internal combustion engine, variable-effect LiBr-H2O absorption cooling, and dehumidification air-conditioning with desiccant coated heat exchangers, was introduced. The temperature and humidity independent strategy was applied in the gasification-based CCHP system to enhance cooling production, in which the variable-effect absorption chiller and desiccant dehumidification air-conditioning were driven by the exhaust heat and jacket heat of the gas engine based on energy cascade, respectively. The operation strategy of the system followed the electric load. Validated by experimental data, a zero-dimensional code of the gasifier with Gibbs free energy minimization, an artificial neural network model of the variable-effect absorption chiller, and a 1-D dynamic model of the dehumidification air-conditioning, were built with reasonable deviations. The results of energetic, economic, and environmental (3E) analyses for the proposed gasification-based CCHP systems that were applied in two different buildings indicate that woody chips are the most favorable feedstock under the climate of Singapore. The total performance is more sensitive to the feedstock cost than to the natural gas cost. This work enables to contribute valuable data to the practical application of the biomass gasification-based CCHP system in Singapore's building sector.

To tackle the increasing global energy demand the climate change problem, the integration of renewable energy and negative emission technologies is a promising solution. In this work, a novel concept called “negative emission hybrid renewable energy system” is proposed for the first time. It is a hybrid solar-wind-biomass renewable energy system with biochar production, which could potentially provide energy generation, carbon sequestration, and waste treatment services within one system. The optimization and the conflicting economic and environmental trade-off of such system has not yet been fully investigated in the literature. To fill the research gap, this paper aims to propose a stochastic multi-objective decision-support framework to identify optimal design of the energy mix and discuss the economic and environmental feasibilities of a negative emission hybrid renewable energy system. This approach maximizes energy output and minimizes greenhouse gas emissions by the optimal sizing of the solar, wind, combustion, gasification, pyrolysis, and energy storage components in the system. A case study on Carabao Island in the Philippines, which is representative of an island-mode energy system, is conducted based on the aim of achieving net-zero emission for the whole island. For the island with a population of 10,881 people and an area of 22.05 km2, the proposed optimal system have significant negative emission capability and promising profitability with a carbon sequestration potential of 2795 kg CO2-eq/day and a predicted daily profit of 455 US$/day.

Surface-modified poly( d , l -lactic-co-glycolic acid) PLGA nanoparticles (NPs) were fabricated via nanoprecipitation for obtaining therapeutic concentration of paclitaxel (PTX) in brain tumor. The cellular uptake and cytotoxicity of NPs were evaluated on C6 glioma cells in vitro, and BALB/c mice were used to study the brain penetration and biodistribution upon intravenous administration. Results showed that by finely tuning nanoprecipitation parameters, PLGA NPs coated with surfactants with a size around 150 nm could provide a sustained release of PTX for >2 weeks. Surface coatings could increase cellular uptake efficiency when compared with noncoated NPs, and d -α-tocopherol polyethylene glycol 1000 succinate (TPGS) showed the most significant enhancement. The in vivo evaluation of TPGS-PLGA NPs showed amplified accumulation (>800% after 96 h) of PTX in the brain tissue when compared with bare NPs and Taxol®. Therefore, PLGA-NPs with PLGA-TPGS coating demonstrate a promising approach to efficiently transport PTX across blood-brain barrier in a safer manner, with the advantages of easy formulation, lower production cost, and higher encapsulation efficiency.