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In the present work, we demonstrated for the first time a simple method for the fabrication of drug-loaded Microbubbles (MBs) by a single step via coaxial electrohydrodynamic atomization (CEHDA). As a proof of concept, a therapeutic agent (tissue plasminogen activator, tPA) and two types of shell materials (phospholipid and bovine serum albumin, BSA) were selected to produce tPA-entrapped MBs. Investigation using fluorescein isothiocyanate (FITC) labelled tPA revealed that the tPA-loaded MBs were successfully fabricated in a one-step procedure and the tPA was located in the shell layer for both the BSA and lipid MBs. By optimization of the operating conditions in terms of voltage, core/shell flow rate ratio as well as tPA volume ratio, minimum bubble sizes for tPA-BSA and tPA-lipid MBs were obtained. The fabricated tPA-BSA MBs was ∼41 μm in mean diameter while ∼41% of the tPA-lipid MBs ranged from 3 to 6 μm and ∼36% of them ranged from 6 to 9 μm under optimal operating conditions. Sensitivity analysis on the effects of key process parameters was also performed to guide design and manipulation of bubble sizes. The investigation of gas phase showed that the usage of sulphur hexafluoride (SF6) as the core can enhance the stability of tPA-lipid bubbles. The presented one-step method displayed great flexibility for producing tPA-loaded MBs and thus can potentially serve as a new tool to generate/engineer tPA-bubbles for applications in ischemic stroke therapy.

In Singapore, approximately 30t/day of carbon-based solid waste are produced from petrochemical processes. This carbon black waste has been shown to possess physical properties that are characteristic of a good adsorbent such as high external surface area. Therefore, there is a growing interest to reutilize and process this carbon black waste into secondary materials such as adsorbents. However, the carbon black waste obtained from petrochemical industries may contain heavy metals that are hazardous to human health and the environment, hence restricting its full potential for re-utilization. Therefore, it is important to examine the possible toxicity effects and toxicity mechanism of carbon black waste on human health. In this study, inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis showed that the heavy metals, vanadium (V), molybdenum (Mo) and nickel (Ni), were present in the carbon black waste in high concentrations. Three human cell lines (HepG2 cells, MRC-5 cells and MDA-MB-231 cells) were used to investigate the toxicity of carbon black waste extract in a variety of in vitro assays. Results from MTS assays indicated that carbon black waste extract decreased the viability of all three cell lines in a dose and time-dependent manner. Observations from confocal microscopy further confirmed this phenomenon. Flow cytometry assay also showed that carbon black waste extract induced apoptosis of human cell lines, and the level of apoptosis increased with increasing waste concentration. Results from reactive oxygen species (ROS) assay indicated that carbon black waste extract induced oxidative stress by increasing intracellular ROS generation in these three human cell lines. Moreover, induction of oxidative damage in these cells was also observed through the alteration of glutathione (GSH) and superoxide dismutase (SOD) activities. Last but not least, by treating the cells with V-spiked solution of concentration equivalent to that found in the carbon black waste extract, V was identified as the main culprit for the high toxicity of carbon black waste extract. These findings could potentially provide insight into the hazards of carbon black waste extract and its toxicity mechanism on human cell lines.

The tumor suppressor protein p53 is the most frequently inactivated, mutated, or deleted transcriptional factor in tumor cells. Recent studies have shown that the negative regulation of p53 by the murine double minute 2 (MDM2) protein in human cells interrupts the p53 apoptotic pathway and causes tumorigenesis. Therefore, the disruption of the MDM2-p53 complex by small molecules such as nutlin-3a and the administration of the active p53 protein can effectively restore the apoptotic activity of the p53 protein in tumor cells. This study aims to introduce a unique combined p53-based gene and chemotherapy approach using core-shell polymeric microparticles for the localized treatment of cancers. Core-shell microparticles were successfully fabricated in a single step using a modified electrohydrodynamic atomization (EHDA) technique, where the core and shell layers were loaded with nutlin-3a and β-cyclodextrin-g-chitosan/p53 nanoparticles, respectively. The grafting of β-cyclodextrin (β-CD) onto chitosan chains demonstrated remarkable cellular uptake (∼5-fold) compared to pure chitosan at N/P = 6, attributed to a strong interaction and temporary disruption of the lipid bilayer in the cell membrane by the synthesized copolymer. The therapeutic efficiencies of single- and dual-agent loaded microparticle formulations were also evaluated and compared against free-drug treatment in terms of cell viability and intracellular expression of p53, caspase 3, and MDM2 proteins via an MTS assay, an enzyme-linked immunosorbent assay, and an immunostaining assay. The results revealed that the controlled and sustained release of both agents from the microparticles synergistically enhanced the anti-proliferative efficacy of the agents via the continuous overexpression of p53 and caspase 3 proteins over 5 days. However, MDM2 protein expression remained at the basal level over that period. The findings also indicated that nutlin-3a could impose excessive oxidative stress on cancer cells, where the overproduction of reactive oxygen species (ROS) with irreversible destructive effects on subcellular organelles such as the nucleus (DNA) and mitochondria could be considered as a secondary apoptotic pathway induced by nutlin-3a. Inspired by the observations, the proposed drug delivery system can serve as a unique and powerful drug and gene delivery system with a far-reaching application in human cancer therapy.

In this work, carbon black waste - a hazardous solid residue generated from gasification of crude oil bottom in refineries - was successfully used for making an absorbent material. However, since the carbon black waste also contains significant amounts of heavy metals (especially nickel and vanadium), chemical leaching was first used to remove these hazardous impurities from the carbon black waste. Acid leaching with nitric acid was found to be a very effective method for removal of both nickel and vanadium from the carbon black waste (i.e. up to 95% nickel and 98% vanadium were removed via treatment with 2M nitric acid for 1h at 20°C), whereas alkali leaching by using NaOH under the same condition was not effective for removal of nickel (less than 10% nickel was removed). Human lung cells (MRC-5) were then used to investigate the toxicity of the carbon black waste before and after leaching. Cell viability analysis showed that the leachate from the original carbon black waste has very high toxicity, whereas the leachate from the treated samples has no significant toxicity. Finally, the efficacy of the carbon black waste treated with HNO3 as an absorbent for dye removal was investigated. This treated carbon black waste has high adsorption capacity (∼361.2mg dye/g carbonblack), which can be attributed to its high specific surface area (∼559m2/g). The treated carbon black waste with its high adsorption capacity and lack of cytotoxicity is a promising adsorbent material. Moreover, the carbon black waste was found to show high electrical conductivity (ca. 10S/cm), making it a potentially valuable source of conductive material.

The impact of algal biochar addition on mesophilic and thermophilic anaerobic co-digestion of algal biomass and food waste was investigated with a focus on semi-continuous operations and functional microbial communities. Under batch co-digestion, the highest co-digestion synergy was observed for a mixture of 25% food waste and 75% algal biomass. During semi-continuous co-digestion of 25% food waste-75% algal biomass mixture, biochar amended digesters exhibited a 12–54% increase in average methane yield (275.8–394.6 mL/gVS) compared to the controls. Elevated temperature induced narrow distributions of volatile fatty acids (VFAs) by inhibiting the production of branched VFAs. Genus Proteiniphilum was selectively enriched by 3.2 folds in mesophilic digesters with biochar amendment while genus Defluviitoga was selectively enriched in thermophilic digesters due to elevated temperature. Methanogenic communities were significantly different in mesophilic and thermophilic digesters. Biochar amendment contributed to shifts in the predominant methanogens leading to a more balanced state of two methanogenic pathways.

Gasification waste, also known as carbon soot, is solid industrial waste from the bottom residual of an oil refinery and contains a substantial amount of toxic vanadium. In this work, we report an ...

Biochar is newly proposed as an innovative and cost-effective material to capture CO

CO2 co-gasification of horticultural waste (HW) and sewage sludge (SS) with addition of ash from waste as catalyst in a fixed-bed lab-scale gasifier was comprehensively investigated using Box-Behnken experiment design. Influence of three operating parameters, i.e. loaded ash content, operating temperature, and gasifying agent flow rate was studied. Among the three parameters, temperature is the main driving force for enhancement of cold gas efficiency (CGE) and higher heating value (HHV) of the produced syngas. An increase in the gasifying agent flow rate is found to positively impact CGE, but to negatively affect the HHV of the produced syngas and the CO2 reduction ratio. The increase in ash content is observed to have a negative effect at the beginning, followed by a positive effect near the end on both CGE and HHV of the produced syngas at low temperature. Mathematical models of good accuracy, with R2 0.994 and 0.989 for CGE and HHV of the produced syngas respectively, were developed for optimization of the different indices of the co-gasification process by response surface methodology (RSM). Finally, a KIVA-CHEMKIN based CFD model was implemented to study the combustion performance of the produced syngas in an internal combustion engine (ICE). The engine efficiency is observed to be proportional to HHV of the produced syngas, while inversely proportional to its CO2 content, which may cause engine failure when exceeds 74%v/v, in the present study. National Research Foundation (NRF) Accepted version This work was supported by the National Research Foundation (NRF), Prime Minister’s Office, Singapore under its Campus for Research Excellence and Technological Enterprise (CREATE) programme. Grant Number R-706-001-102-281, National University of Singapore. Xiang Kan acknowledges the Ph.D. scholarship supported by China Scholarship Council.

Dry mouth or xerostomia is a frequent medical condition among the polymedicated elderly population. Systemic pilocarpine is included in the first line of pharmacological therapies for xerostomia. However, the efficacy of existing pilocarpine formulations is limited due to its adverse side effects and multiple daily dosages. To overcome these drawbacks, a localized formulation of pilocarpine targeting the salivary glands (SG) was developed in the current study. The proposed formulation consisted of pilocarpine-loaded Poly(lactic-co-glycolic acid) (PLGA)/poly(ethylene glycol) (PEG) nanofiber mats via an electrospinning technique. The nanofiber mats were fully characterized for their size, mesh porosity, drug encapsulation efficiency, and in vitro drug release. Mat biocompatibility and efficacy was evaluated in the SG organ ex vivo, and the expression of proliferation and pro-apoptotic markers at the cellular level was determined. In vivo short-term studies were performed to evaluate the saliva secretion after acute SG treatment with pilocarpine-loaded nanofiber mats, and after systemic pilocarpine for comparison purposes. The outcomes demonstrated that the pilocarpine-loaded mats were uniformly distributed (diameter: 384 &plusmn, 124 nm) in a highly porous mesh, and possessed a high encapsulation efficiency (~81%). Drug release studies showed an initial pilocarpine release of 26% (4.5 h), followed by a gradual increase (~46%) over 15 d. Pilocarpine-loaded nanofiber mats supported SG growth with negligible cytotoxicity and normal cellular proliferation and homeostasis. Salivary secretion was significantly increased 4.5 h after intradermal SG treatment with drug-loaded nanofibers in vivo. Overall, this study highlights the strengths of PLGA/PEG nanofiber mats for the localized daily delivery of pilocarpine and reveals its potential for future clinical translation in patients with xerostomia.

In this study, solar thermal power coupled with a direct irradiated solar thermochemical reactor using porous-medium NiFe2O4@ZrO2 oxygen exchange material was investigated by combining experiments to the numerical models. The ability of ZrO2, NiFe2O4, and NiFe2O4@ZrO2 to release/uptake O2 and their CO2-splitting characteristics are analyzed by the thermogravimetric analyzer (TGA) and the microstructural changes and chemical composition of NiFe2O4@ZrO2 are examined by scanning electron microscopy (SEM) and x-ray energy dispersive spectrometer (EDS). The experiment performed with a redox thermochemical reactor under a high-flux solar spectrum resulted in a total of 337.89 mL of CO collected during 46 min of CO2-splitting over NiFe2O4@ZrO2 redox material. Higher CO2-splitting activity of NiFe2O4 resulting in 186.545 μmol/g and 130.707 μmol/g of CO yield at 1293-795 °C and 100 sccm of CO2 flow rate were obtained by TGA at the first and second cycle, respectively. The results of both experiments showed significant CO yield at the early stages of oxygen carriers’ re-oxidation with CO2. This study provided important results that could have significant contributions to the solar thermochemical energy storage and CO2 chemical transformation processes.

Skin regeneration through tissue engineering combines biomaterials compatible with living cells to build a niche of limited duration that can support recapitulating reconstruction of the key features of native human skin. Reconstructed full thickness human skin is a promising platform for studying skin biology and assessing the safety and efficacy of cosmeceutical and clinical skin care products. Yet, as a target tissue for synthetic reconstruction, skin still carries a unique set of challenges, in spite of its well-defined 3D architecture, cell composition, and the constantly improving biocompatible synthetic materials now available to bioengineers. Commercial in vitro skin models are mostly prepared via manual deposition of cells into and onto a suitable extracellular matrix, which is usually difficult to mold into irregular shapes. There is an unmet need to develop a process for systematic 3D bioprinting of biomimetic skin that demonstrates full and efficient differentiation with high reproducibility and good viability, within a practical time frame. This study presents a full-thickness biomimetic skin equivalent fabricated by extrusion-based bioprinting. The 3D bioprinted full thickness skin model has cellular collagen dermal layer that rests on an acellular PCL/collagen scaffold, and is overlaid by sequential extrusion of bioprinted keratinocytes before airlifting for stratification and differentiation. The bioprinted skin constructs are compared with full-thickness human skin constructs produced by manual seeding of cells, in terms of cell proliferation, viability, histology, immunostaining, and barrier properties, to identify quantitative and qualitative differences. This study identifies an opportunity to streamline specific 3D bioprinting approaches to deliver full thickness reconstructed human skin in a reproducible, consistent and potentially scalable manner.

Thermal chemical processing of plastic has been seen as an efficient practice for the disposal and resource utilization facing the current plastic waste problem. A pyrolysis followed by catalytic decomposition process was investigated in this work to produce carbon materials from polypropylene plastic over FeNi catalysts. The effects of both catalysis temperature (600, 700 and 800 °C) and catalyst type on the gaseous yields, as well as the physicochemical properties (morphology, porosity, purity and graphitization degree) of the as-obtained carbon materials were systematically explored. Various technologies including high resolution electron microscopies, temperature programmed oxidation, Raman, X-ray diffraction were used for full characterizations of the as-obtained carbons. Results show that the yields of both carbon and hydrogen gas were significantly proportional to the catalysis temperature. In terms of the physiochemical properties of carbon materials, the low catalysis temperature of 600 °C generated the majority amorphous and disordered carbons, due to the insufficient decomposition reactions and low catalyst activity. Catalysis temperature higher than 700 °C was necessary for the successful growth of carbon nanotubes, while further increase in temperature mainly acted on the yield rather than thermal stability and graphitic degree. High purity multi-walled carbon nanotubes with outer diameters of 20–30 nm and length up to few micrometers were generated with FeNi1 at 800 °C. FeNi1 catalyst synthesized by sol–gel method displayed higher activity towards the production of high quality carbon materials than FeNi2 catalyst at any temperature range investigated, due to the porous structure and the uniform dispersion of metal particles.

Successful simulation of the 3D biodiesel engine relies on the accurate input-parameter tuning of the 3D platform named KIVA4-CHEMKIN, which was time- and resource-consuming through traditional uncertainty analyses or experimental design methods. In this study, the input-parameter tuning was treated as an optimization procedure to minimize the root-mean-square error between the simulated in-cylinder pressure and the experimental in-cylinder pressure. A parallel time-varying hyperparameter surrogate algorithm with a radial basis function was proposed to achieve the goal of a favorable solution and less computation time. The key input parameters—the start of injection, injection duration, Sauter mean radius, fuel temperature, and in-cylinder temperature at the intake valve closure—were tuned within their feasible ranges. A 3D KIVA4-CHEMKIN model, involving a skeletal mechanism of 112 species and 498 reactions, was used to test the effectiveness of the 3D biodiesel engine simulation. Only seven iterations with a total of 84 cases could achieve a favorable solution under a parallel paradigm. The possible limitation of the proposed algorithm lies in the mandatory requirement of parallel computing resources. The parameter tuning had an appreciable impact on the estimation of the in-cylinder pressure. The resultant observation—a delayed start of injection with a short injection duration—helps to produce a better fitting between the simulated pressure curve and the experimental results.

Carbon black waste as waste by-product of oil refineries, exhibits improved specific surface area and is rich in surface functional groups after leaching. In this work, both powdered leached carbon black waste (LCBW) and LCBW-chitosan composite beads prepared via instantaneous gelation method were utilized as adsorbent to study their adsorption capabilities and behaviors for removal of tetracycline (TC) and amoxicillin (Amox) in distilled and tap water. The characterization showed that LCBW is high in specific surface area (~375 m2/g) and contains carboxyl (‒COOH) and hydroxyl (‒OH) groups which are essential to the adsorption. Under the experimental conditions, adsorption capacities ranging from 12 to 205 mg/g were obtained. It was observed that the adsorption performance of powdered LCBW was enhanced by the cations presented in the tap water while the effect was insignificant to LCBW-chitosan beads. The kinetics studies showed that the adsorption of the studied antibiotics on powdered LCBW and composite beads fitted well with pseudo 1st-order and pseudo 2nd-order model, respectively. The fitting of intraparticle diffusion model showed that the adsorption process was not governed solely by intraparticle diffusion. LCBW-chitosan beads was used to investigate the continuous adsorption of TC in a fixed bed column and the experimental data was fitted to Adams-Bohart model and Thomas model.

Nowadays, waste-to-energy systems have attracted more and more attentions. Gasification technology is one of the most important methods of waste-to-energy utilization. For further using the residual heat of the gasification system, a desiccant dehumidification unit with heat recovery using desiccant coated heat exchanger (DCHE) driven by waste heat is developed. Two DCHEs are employed to remove moisture from fresh air. The hot water used in the regeneration process comes from the gasification combined heat and power (CHP) subsystem. Under the typical outdoor condition in Singapore (32 °C, 65% RH), the moisture removal of the system reaches 9.32 g/kgDA, the thermal COP is 0.70, and the waste heat utilization ratio approaches 74.2%. To improve the energy efficiency further, a heat recovery subsystem is adopted to recover the waste heat from the exhausted regeneration air. The recommended pre-regeneration time is 3 min, and the moisture removal is 9.01 g/kg DA, while the thermal COP and waste heat utilization ratio are remarkably increased to 1.34% and 86.5%, respectively. Detailed parametric analyses were carried out, including the influences of the cooling water flow rate, hot water flow rate and hot water temperature. This system combines desiccant coated heat exchangers and the gasification CHP subsystem innovatively to improve the energy utilization of waste-to-energy gasification system, which turns out an effective choice to achieve dehumidification and recover waste heat deeply.

Graphical abstract, Highlights • Non-edible feedstock co-transesterification benefited to mitigate climate change and achieve sustainability. • Nanoparticle catalysts enhanced triglyceride conversion, biodiesel production and properties. • Chicken manure nano-catalyst demonstrated the highest biodiesel yield of 95%. • Nano-catalyst could be reused for three times with an optimal 3% loading. • Density, viscosity and cetane number of the biodiesel met the diesel standards., Key challenges for the application of biodiesel include their high acid value, high viscosity, and low ester content. It is essential to develop later-generation biodiesel from unexploited non-food resources for a more sustainable future. Reuse of biowaste is critically important to address these issues of food safety and sustainability. Thus, the co-transesterification of waste cooking oil (WCO), algal oil (AO) and dimethyl carbonate (DMC) for the synthesis of fatty acid methyl esters (FAMEs) was investigated over a series of nanoparticle catalysts containing calcium, magnesium, potassium or nickel under mild reaction conditions. Nanoparticle catalyst samples were prepared from biowaste sources of chicken manure (CM), water hyacinth (WH) and algal bloom (AB), and characterized using XRD, Raman and FESEM techniques for the heterogeneous production of biodiesel. The catalyst was initially prepared by calcination at 850 °C for 4 h in a major presence of CaxMgyCO3, KCl and K2CO3. The WCO and AO co-conversion of 98% and FAMEs co-selectivity of 95% were obtained over CM nanoparticle catalyst under the reaction conditions of 80 °C, 20 mins and DMC to oil molar ratio of 6:1 with 3% catalyst loading and 3% methanol addition. Under the optimum condition, the density, viscosity, and cetane number of the biodiesel were in the range of diesel standards. Nanoparticle catalysts have been proven as a promising sustainable material in the catalytic transesterification of WCO and AO with the major presence of calcium, magnesium and potassium. This study highlights a sustainable approach via biowaste utilization for the enhancement of biodiesel quality with high ester content, low acid value, high cetane number, and low viscosity.

Electrostatic effect on particle transport in particle-laden turbulent pipe flows at R e b = 44000 was investigated by coupling LES with Lagrange particle tracking technology. The particle governing equation included drag force, lift force and electrostatic force. Triboelectrification and collision electrification were basically considered for particle charging ways in the particle-laden turbulent pipe flows. In this work, three particle St numbers (3.9, 35.6, 142.2) were considered to compare the electrostatic effect on particle behavior. It was found that in the near-wall region, electrostatics destroyed particle aggregation around the vortex structure. Particle-ejection delay effect and particle-sweep premature effect were then proposed in boundary layer due to electrostatics. Electrostatics affected particle distribution and that became more significant with electrostatics increasing. Electrostatics prevented particles from ejecting as particle-ejection delay effect and accelerated particle moving and caused premature occurrence of particle sweep as particle-sweep premature effect. Charged particles were observed to distribute in the low-speed streaks, high-speed streaks, and the region between them, which was caused by particle-ejection delay and particle-sweep premature. It can be concluded that in the turbulent pipe flows electrostatic effect destroyed particle normal distribution under single turbulence effect.

Due to the tar contamination caused by the gasification process of biomass, the internal combustion engine (ICE) based gasification cogeneration systems require complicated gas cleaning devices to purify producer gas. In this paper, a Stirling engine based gasification combined cooling, heat and power (CCHP) system was introduced, which has the capability of mitigating tar condensation and contamination. The gasification CCHP system, including the gasification system, the Stirling engine system, and the absorption chiller system, can provide electricity, heat and cooling for a commercial building. The effects of the equivalence ratio on syngas composition and cold gas efficiency of the gasification process were analyzed herein. The optimal systems in Singapore and Shanghai can save respectively 75.9% and 70.5% levelized total cost compared to a conventional reference system. The Stirling engine based CCHP system had advantages over the ICE systems on overall consideration of the levelized total cost and the primary energy saving ratio. The monthly energetic, economic and environmental performance of the CCHP systems was evaluated under different modes and the above two systems’ primary energy saving ratios, operation cost reduction ratios and CO2 equivalent reduction ratios respectively reached 0.886, 0.462 and 0.701 in Singapore and 0.908, 0.535 and 0.710 in Shanghai in annual operation. The outcomes of this paper contribute to the design and deployment of such a CCHP system, and the developed models and analysis framework can be extended to different climate areas.

Sewage sludge bottom ash, which is the major fraction obtained from the incineration of sewage sludge was treated with various organic and inorganic acids for heavy metal removal, along with a comparative phosphate treatment for heavy metal fixation. Malonic acid, an organic acid, was found to remove heavy metals better as compared to nitric acid, a strong inorganic acid. The acid treated samples were further examined for heavy metal leaching, followed by marine toxicity/abnormality testing of the leachates, where acid treated and phosphate treated ash leachate displayed higher (with malonic acid proving to be most toxic) and similar toxicity profiles as compared to raw ash leachate respectively. Raw ash was tested for its leaching patterns at different liquid/solid ratios(L/S = 5 and 10), salinities and time points (24, 48 and 72 h), where the leaching was found to saturate at L/S = 5 and at 24 h with varied salinity effecting the leaching insignificantly. When raw ash was benchmarked against concrete sand for marine toxicity, a material commonly used for land reclamation, acute toxicity patterns were found to be mostly similar except in case of the sea urchin embryonic assay, where toxicity was detected, indicating the sensitivity of the assay to residual levels of heavy metals. The raw ash was also tested against human cell lines where it displayed size and dose-dependent toxicity. To enable the use of ash for environment applications such as coastal reclamation, appropriate treatments are required to minimize leaching of potential harmful contaminants and this study demonstrates the importance of post-treatment of ash on its subsequent toxicity to organisms.

Tuberculosis (TB) is still a serious public health problem in various countries. One of the long-elusive but critical questions about TB is what the risk factors are and how they contribute for its seasonality. An ecologic study was conducted to examine the association between the variation of outdoor PM2.5 concentration and the TB seasonality based on the monthly TB notification and PM2.5 concentration data of Hong Kong and Beijing. Both descriptive analysis and Poisson regression analysis suggested that the outdoor PM2.5 concentration could be a potential risk factor for the seasonality of TB disease. The significant relationship between the number of TB cases and PM2.5 concentration was not changed when regression models were adjusted by sunshine duration, a potential confounder. The regression analysis showed that a 10 μg/m3 increase in PM2.5 concentrations during winter is significantly associated with a 3% (i.e. 18 and 14 cases for Beijing and Hong Kong, respectively) increase in the number of TB cases notified during the coming spring or summer for both Beijing and Hong Kong. Three potential mechanisms were proposed to explain the significant relationship: (1) increased PM2.5 exposure increases host's susceptibility to TB disease by impairing or modifying the immunology of the human respiratory system; (2) increased indoor activities during high outdoor PM2.5 episodes leads to an increase in human contact and thus the risk of TB transmission; (3) the seasonal change of PM2.5 concentration is correlated with the variation of other potential risk factors of TB seasonality. Preliminary evidence from the analysis of this work favors the first mechanism about the PM2.5 exposure-induced immunity impairment. This work adds new horizons to the explanation of the TB seasonality and improves our understanding of the potential mechanisms affecting TB incidence, which benefits the prevention and control of TB disease.

The low cost and efficient CaO catalysts have been successfully prepared from chicken manure by a simple calcination, in this present work. Chicken manure contains significant content of calcium compounds that can easily be converted into the active calcium oxide catalyst after calcination at 850 °C under air. The Hammett indicator test showed that the obtained CaO catalyst has the basic strength in a range of 15

Biomass gasification with CO2 as the gasifying agent is a promising way to relieve the energy shortage and minimize CO2 emission. In this study, Eulerian method was used to study the CO2 gasification of biomass in a fluidized bed gasifier. It was found that the CO2 percentage in the gasifying mixture with air, the CO2-to-biomass ratio, the moisture content of woodchips, and the woodchip size had great influence on the gasification performance. With the increasing CO2-to-biomass ratio, the mole fraction of CO in the producer gases would be increased while those of H2 and CO2 vary in the opposite trend. When CO2 mass percentage in the gasifying agent was 60%, the fractions of CO and CH4 in the producer gas reached the maximum, as well as the lower heating value and cold gas efficiency, so this was the optimal condition when the gasifier had the best performance. The moisture content and particle size of the woodchips had negative effects on the gasification performance, because of the lower heating value of producer gases, cold gas efficiency and CO2 conversion ratio were both reduced with increasing moisture content and particle size. This study offers a promising way to integrate the gasification of renewable biomass with CO2 capture, and may be helpful in the design and operation of biomass gasifier.

This study aims to present a new intelligent polymeric nano-system used for combining chemotherapy with non-viral gene therapy against human cancers. An amphiphilic copolymer synthesized through the conjugation of low molecular weight polyethyleneimine (LMw-PEI) and poly(e-caprolactone) (PCL) via a bio-cleavable disulfide linkage was successfully employed for the simultaneous delivery of drug and gene molecules into target cells. Compared to the conventional PCL copolymerization pathway, this paper represents a straightforward and efficient reaction pathway including the activation of PCL-diol hydroxyl end groups, cystamine attachment and LMw-PEI conjugation which are successfully performed at mild conditions as confirmed by FTIR and 1 H NMR. Thermal, morphological characteristics as well as biocompatibility of the copolymer were investigated. The copolymer showed great tendency to form positively charged nanoparticles (∼163.1 nm, +35.3 mV) with hydrophobic core and hydrophilic shell compartments implicating its potential for encapsulation of anti-cancer drug and plasmid DNA, respectively. The gel retardation assay confirmed that the nanoparticles could successfully inhibit the migration of pDNA at ∼5 nanoparticle/pDNA w/w. The in vitro cytotoxicity tests and LDH assay revealed that the cationic amphiphilic copolymer was essentially non-toxic in different carcinoma cell lines in contrast to branched PEI 25K. Moreover, the presence of redox sensitive disulfide linkages provided smart nanoparticles with on-demand release behavior in response to reducing agents such as cytoplasmic glutathione (GSH). Importantly, confocal microscopy images revealed that in contrast to free Dox, the nanoparticles were capable of faster internalizing into the cells and accumulating in the perinuclear region or even in the nucleus. Finally, the co-delivery of Dox and p53-pDNA using the copolymer displayed greater cytotoxic effect compared with the Dox-loaded nanoparticle counterpart as revealed by cell viability and Caspase 3 expression assay. These results suggest the copolymer as a promising candidate for the development of smart delivery systems. Statement of Significance We employed cystamine dihydrochloride as a disulfide linkage for the conjugation of PCL diol and low molecular weight PEI segments through a straightforward and efficient reaction pathway at mild conditions. The new copolymer was essentially non-toxic in different carcinoma cell lines and showed great tendency to form positively charged nanoparticles. Therefore, it can be utilized as a promising platform for simultaneous drug and gene delivery to aggressive cancers. The results of drug and gene co-delivery experiments confirmed the pivotal role of disulfide linkage on the controlled release of both drug and gene molecules in response to glutathione concentration gradient between extracellular and intracellular microenvironments. In addition, the co-delivery of doxorubicin and p53 plasmid DNA using the new copolymer displayed greater cytotoxic effect compared with single agent (i.e. Dox) loaded counterpart, which indicated the significance of rapid dissociation of therapeutic agents from the carrier for synergistic cytotoxic effects on cancer cells.

In this study, a computational fluid dynamic (CFD) model was developed to simulate the liquid cone-jet and core-shell droplet formation in the Coaxial Electrohydrodynamic Atomization (CEHDA) process. Validation experiments were conducted using poly(lactic acid) (PLA) and poly(lactic-co-glycolic acid) (PLGA) solutions as core and shell materials, respectively. Good agreement was obtained between experimental results and simulation predictions in terms of both particle size and core-shell structure. Investigation of interfacial tension between core and shell fluids showed that a stable compound cone-jet and droplet can be easily formed using miscible or partially miscible liquids compared with immiscible liquids with higher interfacial tension. It was also found that the nozzle tip configuration has significant effects on droplet production due to differences in fluid motion. The results also showed that the productivity of the CEHDA process, that is, slow production of core-shell microparticles due to low flow rates, could be enhanced using optimal cone-shaped nozzle configuration. Overall, this computational model provided a means of designing and optimizing CEHDA processes for large-scale core-shell microparticle fabrication in pharmaceutical application, such as selections of materials and nozzle configuration. © 2016 American Institute of Chemical Engineers AIChE J, 62: 4259–4276, 2016

Gasification is recognized as a green technology as it can harness energy from biomass in the form of syngas without causing severe environmental impacts, yet producing valuable solid residues that can be utilized in other applications. In this study, the feasibility of co-gasification of woody biomass and food waste in different proportions was investigated using a fixed-bed downdraft gasifier. Subsequently, the capability of biochar derived from gasification of woody biomass in the rehabilitation of soil from tropical secondary forests on degraded land (adinandra belukar) was also explored through a water spinach cultivation study using soil-biochar mixtures of different ratios. Gasification of a 60:40 wood waste-food waste mixture (w/w) produced syngas with the highest lower heating value (LHV) 5.29 MJ/m(3)-approximately 0.4-4.0% higher than gasification of 70:30 or 80:20 mixtures, or pure wood waste. Meanwhile, water spinach cultivated in a 2:1 soil-biochar mixture exhibited the best growth performance in terms of height (a 4-fold increment), weight (a 10-fold increment) and leaf surface area (a 5-fold increment) after 8 weeks of cultivation, owing to the high porosity, surface area, nutrient content and alkalinity of biochar. It is concluded that gasification may be an alternative technology to food waste disposal through co-gasification with woody biomass, and that gasification derived biochar is suitable for use as an amendment for the nutrient-poor, acidic soil of adinandra belukar.

In this work, activated carbon (AC) as an effective and low-cost adsorbent was successfully prepared from carbon residue (or char, one of the by-products from woody biomass gasification) via physical activation. The surface area of char was significantly increased from 172.24 to 776.46m(2)/g after steam activation at 900°C. The obtained activated carbons were then employed for the adsorption of dye (Rhodamine B) and it was found that activated carbon obtained from steam activation exhibited the highest adsorption capability, which is mainly attributed to the higher surface area and the abundance of hydroxyl (-OH) and carboxyl (-COOH) groups on the activated carbon surface. Moreover, it was also found that the adsorption capability significantly increased under the basic condition, which can be attributed to the increased electrostatic interaction between the deprotonated (negatively charged) activated carbon and dye molecules. Furthermore, the equilibrium data were fitted into different adsorption isotherms and found to fit well with Langmuir model (indicating that dye molecules form monolayer coverage on activated carbon) with a maximum monolayer adsorption capability of 189.83mg/g, whereas the adsorption kinetics followed the pseudo-second-order kinetics.

3D printing of cementitious materials is gaining attention in the construction industry. However, convenient methods are needed for integrating reinforcement into 3D-printed concrete. This paper demonstrates the mechanical enhancement offered by a novel form of mortar–polymer laminar composite. The polymer reinforcement is itself extrusion 3D-printed as lattice-like sheets, which are interlaced with mortar layers in a manufacturing process that is compatible with rapid and robotic construction. Displacement-controlled compression tests were carried out on three different composites. One of these was made with normal mortar, while two had added waste material components: biochar or fly ash. Polymer reinforcement increased the overall ductility of all composites that were cured in air-dry condition—the relevant condition for material printed on-site. These ductility improvements were seen even though the addition of the polymer decreased the overall peak compressive stress in all but one case. When mortars contained either biochar or fly ash, incorporating plastic reinforcement provided similar ductility to reinforced mortar without these waste materials. On the other hand, introducing biochar to unreinforced mortar reduced its ductility appreciably. The demonstrated composites may therefore enable increased use of waste materials in cement mixtures for building construction.

Biomass gasification has attracted significant interest as it generates less toxic emissions and the combustion of syngas is more efficient and easier to control than solid fuel combustions. An accurate mathematic model could be used as a cost-effective tool to understand various physical and chemical effects in the gasification process, which is essential for the optimization of thermal efficiency, economic viability and particulate matter (PM) emission reduction. In this work, we have developed a hybrid peripheral fragmentation and shrinking-core model, which considers the intra-particle heat and mass transfer, peripheral fragmentation, porosity evolution and chemical reaction kinetics. The model development involves two steps: the first step is developing a data-driven model to correlate PM emissions with operating conditions based on experimental data; the second step is coupling the PM model in the mass balance of the shrinking-core model to simulate the transient of solid phase mass loss due to peripheral fragmentation. The numerical predictions have been validated with experimental data, and the maximum deviations are 10.24%, 12.95% and 1.47% for syngas, biochar and PM emission, respectively. To the best of the authors’ knowledge, this is the first attempt to quantify syngas generation, biochar production and PM emission in a single model.

Waste-to-energy (WTE) plants are operated worldwide to address the management of municipal solid waste. Against this background, an increasing number of WTE plants serve as combined heat and power (CHP) producers that supply heat to the heating systems in local districts and trade electricity in the regional power markets. This paper studies a short-term operation planning problem of determining effective power trading strategies for WTE CHP plants that participate in day-ahead markets. A two-stage distributionally robust optimization (DRO) model is developed with the consideration of uncertain electricity prices, waste supply, and district heating demand. These different kinds of uncertainty are captured by an ambiguity set that contains a collection of possible probability distributions of the uncertain parameters. The two-stage DRO model seeks to ascertain a power trading strategy that maximizes the expected profit of a WTE CHP plant on a regular operating day under the worst-case distribution in the ambiguity set. As the DRO model is intractable, a solution method based on linear decision rule techniques is designed to reformulate the model as a tractable robust linear program. To test the applicability of the DRO model, a case study with real-world data is conducted. The computational results show that the two-stage DRO model can facilitate a WTE CHP plant in obtaining economical and robust power trading strategies for regular operating days in a day-ahead market. Furthermore, the impacts of the parameters in the ambiguity set on deriving robust power trading strategies for WTE CHP plants are investigated.

The increasing population and continuous urbanization make food security prominent in sustainable development. It is important to develop economic and resource-efficient farming solutions to meet food demand. Renewable energy and waste valorization may bring benefits to build sustainable food production systems and facilitate circular economy. This work aims to develop a decision support framework for the stakeholders to quantitatively assess and optimize their urban farming systems for efficient investment and operation. The proposed framework is based on a holistic system model that considers the energy and material consumption in vegetable production processes and the economic and environmental performance of urban farming systems. In the multi-dimensional assessment model, the net present value and cradle-to-gate CO2 emission, water consumption, and land occupation of different configurations of urban farming systems were assessed. In a further development, the assessment model was embedded in an optimization framework to identify the optimal system design and operation. The optimal crop mix and the corresponding cultivation set points (such as temperature, humidity, irradiance, illumination time, and CO2 concentration) for the farming modules were determined via optimization. To demonstrate the proposed framework, a case study on the design and operation of a vertical farm in Singapore was carried out. The case study examined alternative farming systems with glass-enclosed vs window-free structural design, grid vs solar photovoltaic (PV) energy supply, and traditional chemical fertilizers vs food waste compost fertilization. Results showed that plant-factory farming systems integrated with solar PV and beer-residue-derived fertilizer could be a promising and sustainable farming solution for Singapore as a tropical megacity.

Urban farming has been gaining popularity but the poor urban soil quality has raised concern regarding soil productivity. Biochar generated from waste wood has been widely applied as a soil conditioner, but few studies investigated its effects when used in high concentrations on urban soil. In this study, the effects of biochar on the growth of the leafy vegetable, xiao bai cai (Brassica rapa Cultivar Group Pak Choi Green-petioled Form) were investigated with its concentrations in urban soil varying from 0 to 100% (v/v). The results demonstrated that the 30% biochar and soil mixture (v/v) was best in terms of fresh weight, dry weight and leaf number gain over those of the control (0% biochar). Analysis of the growing medium showed that by increasing the biochar concentrations, available nitrate and potassium as well as cation exchange capacity increased accordingly, while available phosphate decreased. A life cycle assessment showed that the global warming potential could be reduced when applying waste wood-generated biochar as an urban soil amendment for vegetable production.

In this study, the looping materials of Fe2O3, CaO, mechanically mixed CaO and Fe2O3, and chemically synthesized Ca2Fe2O5 were tested for comparison of the performance and gas evolution processes. The reaction mechanism was illustrated to have an insight into the Fe2O3/CaO-based chemical looping process. Results found that the reduction from Fe2O3 to Fe3O4 trended to form CO2 while the transition of Fe3O4 to Fe happened after 650 °C was most likely to release CO. CO2 adsorption by CaO during 400–600 °C and further desorbed at higher temperature for CO2 Boudouard reaction which enhanced the biomass conversion. Mechanically mixed CaO and Fe2O3 maintained the properties of CaO and Fe2O3 with CO2 transfer and oxygen releasing during chemical looping reaction process, while the synthesized Ca2Fe2O5 presented hard reducibility which prefer to generate CO with the highest concentration (34.96 vol%) during chemical looping process at 850 °C.

Biochar is newly proposed as an innovative and cost-effective material to capture CO2. In this study, biochar was produced from feedstock mixtures of food waste and wood waste (i.e., 20%:80% WFW20, 30%:70% WFW30 and 40%:60% WFW40) by gasification. The two biochar adsorbents containing the highest percentage of food waste, i.e., WFW40-K and WFW40-KC, were activated by KOH and KOH + CO2, respectively. The biochar adsorbents were then tested for CO2 adsorption at room temperature of 25 °C by using a volumetric sorption analyzer. The WFW20 showed the highest CO2 adsorption capacity, while higher percentage of food waste in the feedstock was unfavorable for the CO2 adsorption. The presence of N and S on the biochar surface was the primary contributor to the high CO2 uptake on WFW20. The development of micropores by KOH activation significantly increased the CO2 adsorption on WFW40-K, but KOH + CO2 activation could not further increase the development of micropores and subsequent CO2 adsorption. Moreover, WFW40-K showed >99% recyclability during 10 consecutive adsorption-desorption cycles. The biochars derived from biowaste (food waste and wood waste) could be effective adsorbents for CO2 capture by providing green solution for food waste recycling.

Thermo-chemical conversion of waste plastics into clean energy and valuable products can be a promising technology from both economic and environmental perspectives. In this work, pyrolysis and in-line catalytic decomposition of polypropylene was performed for production of hydrogen and carbon nanomaterials. A series of novel Fe/Ni catalysts were prepared, and the effects of catalyst active metal component (Fe, Ni, FeNi) and synthesis method (sol–gel and impregnation) were explored. Results show that the production of hydrogen and solid products was in a descending order as Fe-Ni, Fe and Ni loading, while sol–gel prepared catalysts were more catalytic effective than their impregnated counterparts. FeNi(SG) exhibited an optimal activity with productions of 25.14 mmol/gplastic of hydrogen and 360 mg/gplastic of high quality carbon nanomaterials, which was attributed to (i) uniform mesoporous structure with 212.30 m2/g specific surface area (ii) high dispersion degree (42.02%) of active metals and (iii) enhanced reducibility originated from the synergistic effect between Fe and Ni. Carbon nanomaterials which contained the majority of carbon nanotubes were comprehensively characterized in terms of structure complexity, morphology and graphitization degree, and the formation mechanism of bamboo-like multi-walled carbon nanotubes from pyrolysis and catalytic decomposition of polypropylene was also discussed.

Alkaline activated materials such as geopolymers and cementitious materials derived from pozzolanic reactions offer several advantages over the currently widely used Portland cement, especially in terms of environmental sustainability and physiochemical properties. However due to the need of an alkaline activator, such as NaOH or KOH, which result in high production cost and requires skilled personnel, they have not been deeply explored and put to use. Here in this study, wood fly ash, a by product of wood combustion is used as an alternative source of alkaline activator for producing such alkaline activated materials along with coal fly ash, where the resulting geopolymer-cementitious hybrid (GCH) was characterized physico-chemically through electron microscopy, BET, FTIR, XRF & XRD. However, the leaching of heavy metals from the wood fly ash could potentially pose an environmental concern. Therefore, the focus of this study is to reduce the leachability factor of wood fly ash involved in the alkaline activated process and to understand the effects of various factors (i.e. water-to-ash ratio (w/a), method of curing, type of alkaline activator and ash sieving) on the leaching process, through factorial experimental analysis. The leaching patterns of various elements such as Pb, Zn, Cr, As. Hg, Se were studied along with the contributing factors and results showed that the dominant factor was the type of alkaline activator (i.e. Wood Fly Ash versus Na2SiO3). By comparing the leaching data to Denmark's leaching criteria, the best performing GCH sample was found to be 0.3DI_p_s (0.3 represents the w/a ratio, "p" denotes that samples were precured and "s" denotes sieving).

Biochars can be a potential means of CO2 capture if designed with hierarchical structures and suitable surface properties. Objective of this research was to assess the effectiveness of KOH activation and a combination of KOH and CO2 activation for enhancing the CO2 adsorption capacity of gasification biochar. Biochars were produced with either 100% wood chips (W) or a mixture of 70% wood chips and 30% chicken manure (WCM) through gasification, and then activated using either 1 M KOH (sample label appended with “K”) or 1 M KOH and 500 mL CO2 min−1 at 850 °C (sample label appended with “KC”). The pristine and activated biochars were evaluated in terms of physicochemical properties, CO2 adsorption capacity at 25 °C, adsorption kinetics, and regeneration ability. The WCMK biochar exhibited the highest CO2 adsorption capacity (2.92 mol/kg) with highest surface area (1408 m2/g), micropore area (690.18 m2/g), and micropore volume (0.36 cm3/g). WKC and WK showed comparable CO2 adsorptions, both of which were lower than that of WCMK. Both WCMK and WKC showed considerable selectivity for CO2 over N2, fast adsorption and excellent regeneration abilities over 10 consecutive adsorption-desorption cycles. Activation of biochar, either with KOH or KOH + CO2, enhanced its CO2 adsorption capacity due to an increase in surface area and microporosity, irrespective of the feedstock type. However, hydrophobicity, and aromaticity of biochar and presence of hetero atoms (N and S) also positively influenced CO2 adsorption capacity of biochar. Both KOH and KOH + CO2 activation will be promising options for enhancing CO2 adsorption capacity of pristine biochar irrespective of the feedstock type.

Waste-to-energy (WTE) technologies provide effective solutions to the compelling challenges of waste management and the energy crisis globally. Many WTE plants utilize the combined heat and power (CHP) operation mode where both electricity and heat can be generated simultaneously. Thus, these WTE CHP plants can supply heat to the local district heating systems and trade power in the electricity markets. As such plants have the responsibilities of treating waste and of fulfilling the allocated district heating demand, necessary operational tasks such as preventive maintenance actions for the production units should be scheduled and performed periodically to ensure their continuous and reliable operations. This paper studies the scheduling of operational tasks in WTE CHP plants that participate in electricity markets and are connected to district heating networks. Firstly, we formulate a two-stage robust optimization model considering the uncertainty of electricity market prices, heat demand, and waste supply. The objective is to derive the robust optimal schedule that maximizes the worst-case operating profit of a WTE CHP plant under uncertainty. Subsequently, we design a constraint generation algorithm for the two-stage robust optimization model. Finally, a case study of scheduling preventive maintenance tasks is conducted for the production units of a WTE CHP plant over a 30-day horizon. The robust schedule thus derived is evaluated by Monte Carlo simulation tests and further compared to the deterministic schedule generated without the consideration of uncertainty. The simulation results show that the robust schedule enables an average profit of 877021.21€ to be attained for the plant over the scheduling horizon. Moreover, it improves the robustness of its deterministic counterpart from 68.4% to 98.8% with an increase of only 0.3% of the operating profit of the plant. In addition, a comprehensive sensitivity analysis is performed to investigate the impacts of different types of uncertainty on the robust schedule for the WTE CHP plant.

Effectiveness of biochar addition to enhance thermophilic semi-continuous anaerobic digestion (AD) of food waste for methane production was investigated with a focus on dosage and particle size of biochar, pilot-scale application and elucidation of methanogenic pathways. Optimal dosage range of biochar was determined as 7.5 to 15 g per L working volume based on lab-scale batch AD. Effects of biochar with different particle sizes at a model dosage of 15 g/L were evaluated in a semi-continuous AD experiment, results of which showed that all the examined biochars with different particle sizes (

In this study, horticultural waste (HW) and sewage sludge (SS) with different mass ratios were co-gasified with steam at different temperatures to investigate the product distribution, gas synergistic interaction, and optimal design for gas products from co-gasification process. Results showed that with the increase of SS ratio in blends, the H2 content was increased and the syngas yield was decreased. The synergistic interaction was more significant at higher temperature which promoted the H2 production probably due to the reduction and steam oxidation of Fe species in SS during co-gasification process. The optimized highest effective gas content (82.92 vol%) was achieved with the highest HHV (11.40 MJ/m3) at the conditions of SS ratio = 0.80 and temperature of 900 °C. It indicates that steam co-gasification of HW and SS is a promising technology to produce desired syngas towards a clean and efficient waste management process.

A fluidized-bed based solar steam gasification of sewage sludge for production of high-quality syngas with a high content of hydrogen is numerically modeled and validated by experimental data generated from a lab-scale fluidized bed. The solar gasifier is mainly composed of a fluidized bed and a concentrically tubular cavity. A transient model coupling a two-phase fluidization model (in terms of reaction kinetics and hydrodynamics) and a solar cavity receiver model is established to conduct the parametric investigation of the proposed solar gasifier, including the effects of the direct normal irradiance, gasifying agent composition, and spatial flux distribution at the freeboard wall on the performance criteria of solar gasification i.e. solar upgraded ratio and solar-to-fuel efficiency. The transient simulation of the solar gasifier with ~2.2 MW solar power input is performed. A H2 yield range of 61.2–67.6 g/kg(sludge) can be achieved through solar steam gasification of sewage sludge, which can be adjusted by modifying the steam content of the gasifying agent and the direct normal irradiance. Under the condition of the direct normal irradiation of 1000 W/m2, the mean concentration ratio of 1000 suns at the dense bed, and 100 vol% N2 content, a maximum solar upgraded ratio of 1.0 and solar-to-fuel efficiency of 0.26 can be achieved.

This work optimized the operation of a syngas-fueled spark ignition (SI) engine in the gasifier-generator (GG) system to achieve improved combustion performance and reduced emission adapting to the electrical power output. The combustion performance and emissions of the SI engine were modeled by an experimentally validated 3D KIVA4-CHEMKIN model with a detailed GRI 3.0 mechanism. Effects of the ignition timing (IT), fuel–air equivalence ratio (FAER), inlet temperature, and power load on the energetic, knock and environmental performance of the SI engine were investigated by analyzing the in-cylinder pressure, heat release, indicated thermal efficiency (ITE), NOx emission, peak temperature and maximum pressure derivative (MPD). When IT increases from 14 to 50 crank angle degrees (CAD) before top dead center (BTDC), the ITE first increases and then decreases, while the NOX emission, peak temperature, and MPD keep increasing. In the range of IT from 14 to 50 CAD, FAER from 0.5 to 0.9, inlet temperature from 300 to 407 K, potential space of optimization variables was figured out in the phase diagram of NOx emission vs. ITE at each power load of 4–10 kW. The optimal IT, FAER, and intake air temperature parameters were selected from the Pareto front of the potential optimization space using the ideal point method. The results show that the load-related control strategy can achieve high ITE values of 39.01–39.69% and satisfactory nitrogen oxide emissions of 0.6–1.55 g/kWh. The optimization method and optimal operation parameters provide references for improving engine performance in the GG system.

Three dual-fuel strategies, i.e. Strategy S (syngas-biodiesel), Strategy U (upgraded syngas-biodiesel), and Strategy D (DME-biodiesel), for utilization of syngas and biodiesel from biomass wastes in internal combustion engines have been proposed in this study. To compare both the combustion and emission performance of the three strategies, an integrated KIVA4-CHEMKIN CFD platform was constructed implementing a newly combined reaction mechanism. Effects of three dual-fuel strategies have been compared against each other in terms of indicated power, NOx and soot emission. At different engine loads, it was found that the indicated power of all strategies increased with the increasing supplement ratio. Strategy S and Strategy U predict higher indicated power than Strategy D at the high engine load, while lower indicated power than Strategy D at the low engine load. As regards to the NOx emission, an increase in the fuel supplement ratio increases the NOx emission (g/kWh) for both Strategy S and Strategy U at high engine loads, while decreases the NOx emission (g/kWh) due to the enhanced indicated power. Strategy D has relatively higher NOx emission (g/kWh) than Strategy S and Strategy U at all loads. With the increase in fuel supplement ratio, the soot emission generally shows a decreasing trend at all engine loads for all strategies, and Strategy D emits less soot than Strategy S and Strategy U in the cases of high fuel supplement ratio (>0.4) for all engine load conditions.

Biomass-derived chemical looping gasification is a novel technology to convert biomass into renewable hydrogen-enriched syngas. In this study, bimetallic Fe-Ca oxides were synthesized to be used as oxygen carriers to promote the hydrogen production from the chemical looping gasification of rice straw. The effects of Fe/Ca ratio, temperature together with the cyclic performance of oxygen carrier were studies in terms of produced syngas distribution, solid structure evolution and the durability of oxygen carrier. Results found that two types of calcium ferrites (Ca2Fe2O5 and CaFe2O4) were formed with different Fe/Ca ratios, and Fe and Ca were uniformly distributed within oxygen carriers by wet impregnation method. Compared with pyrolysis or steam gasification, the hydrogen production was largely promoted during the steam chemical looping gasification process due to the iron re-oxidation by steam. When the ratio of Fe:Ca was1:1, the formed oxygen carrier (Ca2Fe2O5) produced the highest hydrogen yield (23.07 mmol/g biomass) at 800 °C, which benefited from one step reduction and oxidation properties of Ca2Fe2O5. A temperature of no less than 800 °C was needed for the completed redox of Ca2Fe2O5 during chemical looping gasification with steam. The cyclic stability test for Ca2Fe2O5 showed that the continuously accumulated Si from biomass ash would destroy the bimetallic Fe-Ca structure to generate CaSiO3 and Fe2O3 after 3 times of cycle, and this led to the decreased hydrogen production during chemical looping gasification cycle. The great hydrogen selectivity of Fe:Ca = 1:1 (Ca2Fe2O5) makes it a suitable candidate of oxygen carrier, but the cyclic durability should be enhanced to enable a better application for chemical looping gasification conversion of biomass.

Anaerobic digestion (AD) is a potential biotechnology to treat food waste for both energy and resource recovery. However, a high level of contamination in food waste limits their direct use as feedstocks. Therefore, a food waste sorting system followed by anaerobic digestion and gasification is proposed in this study to evaluate the potential of food waste for hydrogen and methane co-production through the thermal-equilibrium model and experimental study. To achieve the H2-rich syngas and methane-rich biogas, the waste sorting system was used to separate the raw waste into pure food waste fraction for AD and discarded waste fraction for gasification. The thermal-equilibrium model is used to predict the content of H2 at different moisture content and air equivalence ratio (ER). The results show that gasification generated the highest hydrogen content at 28.9% with a high moisture content of 55 wt% when the value of ER is 0.35. The highest calorific value of syngas is 5.59 MJ/m3 at the conditions of 60 wt% of moisture content and 0.35 of ER. For the mesophilic AD system, the highest specific methane yield of FW is 557 mL/g VS. Thermophilic AD increased methane yield to 680 mL/g VS while AD of vegetable waste had a negligible production of methane gas. The overall energy performance of the integrated AD and gasification system was assessed in terms of the output of electricity and heat.

This work developed a framework to predict the energy and economic impacts of solar photovoltaic soiling. This framework includes the effects of relative humidity, precipitation and tilt angle on solar photovoltaic soiling. A concept of relative net-present value change was introduced to determine the optimal cleaning interval. The uncertainties in the economic analysis were accounted for using a Monte Carlo simulation method. The framework was used to study the soiling-induced efficiency and economic losses of solar photovoltaic modules in seven cities (i.e. Taichung, Tokyo, Hami, Malibu, Sanlucar la Mayor, Doha, and Walkaway). Overall, the efficiency loss (in ascending order) for Tokyo/Walkaway

Convection enhanced delivery is promising to overcome the blood brain barrier. However, the treatment is less efficient in clinic due to the rapid elimination of small molecular drugs in brain tumours. In this study, numerical simulation is applied to investigate the convection enhanced delivery of liposome encapsulated doxorubicin under various conditions, based on a 3-D brain tumour model that is reconstructed from magnetic resonance images. Treatment efficacy is evaluated in terms of the tumour volume where the free doxorubicin concentration is above LD90. Simulation results denote that intracerebral infusion is effective in increasing the interstitial fluid velocity and inhibiting the fluid leakage from blood around the infusion site. Comparisons with direct doxorubicin infusion demonstrate the advantages of liposomes in enhancing the doxorubicin accumulation and penetration in the brain tumour. Delivery outcomes are determined by both the intratumoural environment and properties of therapeutic agents. The treatment efficacy can be improved by either increasing the liposome solution concentration and infusion rate, administrating liposomes in the tumour with normalised microvasculature density, or using liposomes with low vascular permeability. The delivery is less sensitive to liposome diffusivity in the examined range (E-11~E-7 cm2/s) as convective transport is dominative in determining the liposome migration. Drug release rate is able to be optimised by keeping a trade-off between enhancing the drug penetration and providing sufficient free doxorubicin for effective cell killing. Results from this study can be used to improve the regimen of CED treatments.

Carbon black waste, an oil refinery waste, contains a high concentration of vanadium(V) leftover from the processing of crude oil. For the sake of environmental sustainability, it is therefore of interest to recover the vanadium as useful products instead of disposing of it. In this work, V was recovered in the form of vanadium-based metal-organic frameworks (V-MOFs) via a novel pathway by using the leaching solution of carbon black waste instead of commercially available vanadium chemicals. Two different types of V-MOFs with high levels of crystallinity and phase purity were fabricated in very high yields (98%) based on a coordination modulation method. The V-MOFs exhibited well-defined and controlled shapes such as nanofibers (length:10 μm) and nanorods (length: ∼270 nm). Furthermore, the V-MOFs showed high catalytic activities for the oxidation of benzyl alcohol to benzaldehyde, indicating the strong potential of the waste-derived V-MOFs in catalysis applications. Overall, our work offers a green synthesis pathway for the preparation of V-MOFs by using heavy metals of industrial waste as the metal source.

Syngas and biochar are two main products from biomass gasification. To facilitate the optimization of the energy efficiency and economic viability of gasification systems, a comprehensive fixed-bed gasification model has been developed to predict the product rate and quality of both biochar and syngas. A coupled transient representative particle and fix-bed model was developed to describe the entire fixed-bed in the flow direction of primary air. A three-region approach has been incorporated into the model, which divided the reactor into three regions in terms of different fluid velocity profiles, i.e. natural convection region, mixed convection region, and forced convection region, respectively. The model could provide accurate predictions against experimental data with a deviation generally smaller than 10%. The model is applicable for efficient analysis of fixed-bed biomass gasification under variable operating conditions, such as equivalence ratio, moisture content of feedstock, and air inlet location. The optimal equivalence ratio was found to be 0.25 for maximizing the economic benefits of the gasification process.