Ca-Fe-Si material (CIS), a novel composite material rich in calcium, iron, manganese and silicon showed marvelous immobilization properties for heavy metal(loid)s in soils. To elucidate the acid stability of Cd fixed by CIS (CIS-Cd) and the underlying immobilization mechanisms, the acid dissolution characteristics of CIS-Cd were investigated by using acid titration method and X-ray diffraction (XRD) technique. The results showed that CIS-Cd had distinctive acid buffering capacity in different pH ranges. Based on the titration curve between dissolution rate of CIS-Cd and pH, CIS-Cd can be divided into non acid-stable Cd (9.4%), moderately acid-stable Cd (22.5%) and acid-stable Cd (68.1%). XRD analysis of CIS-Cd at different pH intervals and the correlation curves of dissolution rates of Cd and concomitant elements indicated that non acid-stable Cd was mainly bound by carbonate, silicate and sulfate (CdCO3, Cd2SiO4 and CdSO4) or co-precipitated with the corresponding calcium salts. Moderately acid-stable Cd was mainly bound by magnesium-aluminum-silicon containing minerals or electrically bound by manganese iron minerals. Acid-stable Cd remaining undissolved at pH < 2.42 included CdFe2O4 and ferromanganese minerals strongly bound Cd. It was by multilateral fixation mechanisms that Ca-Fe-Si material possessed marvelous immobilization capability for Cd and strong resilience to environmental acidification as well. The findings implicated that proper combination of calcium-iron-silicon containing minerals could develop novel promising amendments with high efficiency in heavy metal(loid)s immobilization and strong resilience to environmental change.
Salt-tolerant rice (sea rice) is a key cultivar for increasing rice yields in salinity soil. The co-existence of salinity and cadmium (Cd) toxicities in the plant-soil system has become a great challenge for sustainable agriculture, especially in some estuaries and coastal areas. However, little information is available on the Cd accumulating features of sea rice under the co-stress of Cd and salinity. In this work, a hydroponic experiment with combined Cd (0, 0.2, 0.8 mg/L Cd²⁺) and saline (0, 0.6%, and 1.2% NaCl, W/V) levels and a pot experiment were set to evaluate the Cd toxic risks of sea rice. The hydroponic results showed that more Cd accumulated in sea rice than that in the reported high-Cd-accumulating rice, Chang Xianggu. It indicated an interesting synergistic effect between Cd and Na levels in sea rice, and the Cd level rose significantly with a concomitant increase in Na level in both shoot (r = 0.54, p < 0.01) and root (r = 0.66, p < 0.01) of sea rice. Lower MDA content was found in sea rice, implying that the salt addition probably triggered the defensive ability against oxidative stress. The pot experiment indicated that the coexistent Cd and salinity stress further inhibited the rice growth and rice yield, and the Cd concentration in rice grain was below 0.2 mg/kg. Collectively, this work provides a general understanding of the co-stress of Cd and salinity on the growth and Cd accumulation of sea rice. Additional work is required to precisely identify the phytoremediation potential of sea rice in Cd-polluted saline soil.
Several mathematical models have been developed to investigate the dynamics SARS-CoV-2 and its different variants. Most of the multi-strain SARS-CoV-2 models do not capture an important and more realistic feature of such models known as randomness. As the dynamical behavior of most epidemics, especially SARS-CoV-2, is unarguably influenced by several random factors, it is appropriate to consider a stochastic vaccination co-infection model for two strains of SARS-CoV-2. In this work, a new stochastic model for two variants of SARS-CoV-2 is presented. The conditions of existence and the uniqueness of a unique global solution of the stochastic model are derived. Constructing an appropriate Lyapunov function, the conditions for the stochastic system to fluctuate around endemic equilibrium of the deterministic system are derived. Stationary distribution and ergodicity for the new co-infection model are also studied. Numerical simulations are carried out to validate theoretical results. It is observed that when the white noise intensities are larger than certain thresholds and the associated stochastic reproduction numbers are less than unity, both strains die out and go into extinction with unit probability. More-over, it was observed that, for weak white noise intensities, the solution of the stochastic system fluctuates around the endemic equilibrium (EE) of the deterministic model. Frequency distributions are also studied to show random fluctuations due to stochastic white noise intensities. The results presented herein also reveal the impact of vaccination in reducing the co-circulation of SARS-CoV-2 variants within the given population.
Corneal transplantation is the most effective clinical treatment for corneal defects, but it requires precise size of donor corneas, surgical sutures, and overcoming other technical challenges. Postoperative patients may suffer graft rejection and complications caused by sutures. Ophthalmic glues that can long-term integrate with the corneal tissue and effectively repair the focal corneal damage are highly desirable. Herein, a hybrid hydrogel consisting of porcine decellularized corneal stroma matrix (pDCSM) and methacrylated hyaluronic acid (HAMA) was developed through a non-competitive dual-crosslinking process. It can be directly filled into corneal defects with various shapes. More importantly, through formation of interpenetrating network and stable amide bonds between the hydrogel and adjacent tissue, the hydrogel manifested excellent adhesion properties to achieve suture-free repair. Meanwhile, the hybrid hydrogel not only preserved bioactive components from pDCSM, but also exhibited cornea-matching transparency, low swelling ratio, slow degradation, and enhanced mechanical properties, which was capable of withstanding superhigh intraocular pressure. The combinatorial hydrogel greatly improved the poor cell adhesion performance of HAMA, supported the viability, proliferation of corneal cells, and preservation of keratocyte phenotype. In a rabbit corneal stromal defect model, the experimental eyes treated with the hybrid hydrogel remained transparent and adhered intimately to the stroma bed with long-term retention, accelerated corneal re-epithelialization and wound healing. Giving the advantages of high bioactivity, low-cost, and good practicality, the dual-crosslinked hybrid hydrogel served effectively for long-term suture-free treatment and tissue regeneration after corneal defect.
Cancer therapies based on energy conversion, such as photothermal therapy (PTT, light-to-thermal energy conversion) and photodynamic therapy (PDT, light-to-chemical energy conversion) have attracted extensive attention in preclinical research. However, the PTT-related hyperthermia damage to surrounding tissues and shallow penetration of PDT-applied light prevent further advanced clinical practices. Here, we developed a thermoelectric therapy (TET) based on thermoelectric materials constructed p-n heterojunction (SrTiO3/Cu2Se nanoplates) on the principle of light-thermal-electricity-chemical energy conversion. Upon irradiation and natural cooling-induced the temperature gradient (35–45 oC), a self-build-in electric field was constructed and thereby facilitated charges separation in bulk SrTiO3 and Cu2Se. Importantly, the contact between SrTiO3 (n type) and Cu2Se (p type) constructed another interfacial electric field, further guiding the separated charges to re-locate onto the surfaces of SrTiO3 and Cu2Se. The formation of two electric fields minimized probability of charges recombination. Of note, high-performance superoxide radicals and hydroxyl radicals’ generation from O2 and H2O under catalyzation by separated electrons and holes, led to intracellular ROS burst and cancer cells apoptosis without apparent damage to surrounding tissues. Construction of bulk and interfacial electric fields in heterojunction for improving charges separation and transfer is also expected to provide a robust strategy for diverse applications.
This research takes a post-postmodern stance to investigate tourists' predisposition toward alterreal authenticity (i.e., altered reality). It draws on Schachter's two-factor theory of emotion to highlight a model that examines the effects of authenticity and cultural difference, and their interactions on cultural-heritage consumption, through a field experiment. Results point to a two-step mechanism in authenticity negotiation in which psychological arousal is diffused through exposure to authenticity stimuli followed by cognition of the arousal situation conditioned upon tourist cultural background. This research not only heeds the call from the literature to enrich the methodological silos in authenticity discourse through causal inferences; it also provides early empirics to the post-postmodern view of authenticity, which conjectures means for tourists to imaginatively authenticate their experiences.
Most existing deep learning (DL)-based health prognostic methods assume that the training and testing datasets are from identical machines operating under similar conditions requiring massive labelled condition monitoring (CM) data to guarantee the prediction accuracy and generalisation capacity. However, these strict restrictions significantly hinder the deployment of the dl-based prognostic methods in real industries. In this paper, a Bayesian semi-supervised transfer learning with active querying-based intelligent fault prognostic framework is developed for remaining useful life (RUL) prediction across completely different machines under limited data. The proposed method strategically integrates the advantages of transfer learning (TL) and active learning in the Bayesian deep learning (BDL) framework. In the proposed framework, Bayesian neural networks with Monte Carlo dropout inference are utilised to quantify RUL prediction uncertainty, which is further leveraged to develop an active querying-based training data selection mechanism. Moreover, TL is simultaneously embedded into the BDL framework to relieve data distribution discrepancies existing among the completely different machines. The experimental verifications from open-sourced bearing datasets and lab testing-based lithium-ion battery degradation datasets demonstrate that the proposed framework can effectively and reliably achieve bi-directional transfer fault prognostic tasks under limited labelled CM data in target domain. Finally, generalisation and superiority of the proposed method are also validated by comparing with other state-of-the-art methods.
Nanoparticle-based therapeutics represent potential strategies for treating atherosclerosis; however, the complex plaque microenvironment poses a barrier for nanoparticles to target the dysfunctional cells. Here, we report reactive oxygen species (ROS)-responsive and size-reducible nanoassemblies, formed by multivalent host-guest interactions between β-cyclodextrins (β-CD)-anchored discoidal recombinant high-density lipoprotein (NP³ST) and hyaluronic acid-ferrocene (HA-Fc) conjugates. The HA-Fc/NP³ST nanoassemblies have extended blood circulation time, specifically accumulate in atherosclerotic plaque mediated by the HA receptors CD44 highly expressed in injured endothelium, rapidly disassemble in response to excess ROS in the intimal and release smaller NP³ST, allowing for further plaque penetration, macrophage-targeted cholesterol efflux and drug delivery. In vivo pharmacodynamicses in atherosclerotic mice shows that HA-Fc/NP³ST reduces plaque size by 53%, plaque lipid deposition by 63%, plaque macrophage content by 62% and local inflammatory factor level by 64% compared to the saline group. Meanwhile, HA-Fc/NP³ST alleviates systemic inflammation characterized by reduced serum inflammatory factor levels. Collectively, HA-Fc/NP³ST nanoassemblies with ROS-responsive and size-reducible properties exhibit a deeper penetration in atherosclerotic plaque and enhanced macrophage targeting ability, thus exerting effective cholesterol efflux and drug delivery for atherosclerosis therapy.
Over 300 billion of cells die every day in the human body, producing a large number of endogenous apoptotic extracellular vesicles (apoEVs). Also, allogenic stem cell transplantation, a commonly used therapeutic approach in current clinical practice, generates exogenous apoEVs. It is well known that phagocytic cells engulf and digest apoEVs to maintain the body's homeostasis. In this study, we show that a fraction of exogenous apoEVs is metabolized in the integumentary skin and hair follicles. Mechanistically, apoEVs activate the Wnt/β-catenin pathway to facilitate their metabolism in a wave-like pattern. The migration of apoEVs is enhanced by treadmill exercise and inhibited by tail suspension, which is associated with the mechanical force-regulated expression of DKK1 in circulation. Furthermore, we show that exogenous apoEVs promote wound healing and hair growth via activation of Wnt/β-catenin pathway in skin and hair follicle mesenchymal stem cells. This study reveals a previously unrecognized metabolic pathway of apoEVs and opens a new avenue for exploring apoEV-based therapy for skin and hair disorders.
The complex nonstationary interconnection between cardiovascular and respiratory systems ensures the normal metabolism of the human body. However, the dynamic and multiscale characteristics of the interconnection are not fully understood, especially the alterations of cardiac sympathetic-parasympathetic and cardio-respiratory couplings. In this study, modified multiscale transfer entropy (MMTE) was proposed and applied to investigate the intra- and inter-couplings of cardio-respiratory systems. In the experiment, 18 healthy young subjects were recruited to finish the meditation task, and electrocardiogram (ECG) and respiratory signals were recorded in the pre-, during-, and post-task phases. A simulation study has been conducted to test the reliability of MMTE by cardio-respiratory and sympathetic-parasympathetic dynamics models. For the two physiological simulation models, MMTE on scales 10–20 possessed the ability in noise abatement and superior reliability of quantifying coupling strength to that on other scales. Experimental results showed significantly increased MMTE values from the respiratory series to the RR interval series (the time intervals between consecutive R waves of the ECG) over multiple time scales compared with the opposite direction. The same is true for the MMTE values from low frequency (LF) to high frequency (HF) components of the RR interval series. Moreover, the MMTE values between respiratory and RR interval series and between LF and HF series in the during-task phase were significantly smaller than those in other phases. These findings expand the existing mechanism of intra- and inter-couplings of cardio-respiratory systems induced by meditation. Further research is needed to validate and promote the clinical applications.
3D surface reconstruction plays a vital role in augmented reality, virtual reality, and robotics. Previous work can obtain high-quality mesh when the input data is dense and evenly distributed. Although many reconstruction algorithms that can get high-quality meshes have been proposed, the quality of the obtained meshes will be degraded when encountering some particular circumstances, such as noise and data missing. This article introduces a surface reconstruction method with good performance despite non-uniformly distributed and missing data. We supplement the input with the sketch and estimate the normal of the sketch globally based on Duchon energy which makes the estimated normal accurate and smooth. Then we use the signed distance function, whose zero iso-surface represents the surface, to combine the sketch with the original input and compute the implicit function as the solution of a sparse linear system. The experimental results show that this method can generate a high-quality mesh. The use of smoothness energy allows our approach to be much more resilient to sampling imperfections than existing methods. In addition, the technique can add sketches to existing models to obtain 3D models that are more in line with the creator’s intent.
Rechargeable Zn-air batteries (R-ZABs) are promising electrochemical energy storage devices with the advantages of high theoretical energy density, low cost of Zn metal and environment-friendliness. ZABs with neutral electrolytes can avoid or mitigate many side reactions harassing alkaline ZABs because neutral electrolyte is mild and green, which is conducive to battery life. However, the development of neutral ZABs is still in an initial stage. In this review, we would like to summarize the recent progress of neutral electrolytes and electrocatalysts, which are applied in or beyond ZABs. The working mechanism of ZABs is first introduced, especially oxygen electrochemistry on cathode. After elucidating the disadvantages of alkaline electrolytes, several neutral and near-neutral electrolytes are then summarized on developments as well as challenges, such as inorganic/organic salt solutions, high concentration electrolytes and quasi-solid electrolytes. Next, different cathode structures and their impacts on catalysts are presented. The latest progress of different catalysts in neutral electrolytes are classified and summarized, including metal oxides, metal phosphides/sulfides, metal phosphates, single-atom catalysts, etc. Finally, we conclude with a summary and propose a brief outlook for the future developments of electrolytes and oxygen catalysts applied in neutral ZABs.
Failure of soil slopes is often associated with instability of soils. Instability refers to a behavior in which large plastic strains are generated rapidly when a soil element sustains a given load or stress. Currently, the research related to instability of soils is primarily conducted at saturated conditions through undrained triaxial tests on loose saturated soils (e.g., Lade, J Geotech Eng 118:51–72, 1992; Leong et al., Geotech Test J 23:178–192, 2000; Yang, Geotechnique 52:757–760, 2002) and drained constant shear tests on saturated medium and dense sands (Chu et al., Can Geotech J 40:873–885, 2003). However, many natural soil deposits encountered in engineering practice are often unsaturated. During rainfall infiltration, a reduction in soil suction causes a decrease in the shear strength, which leads to the development of plastic strains and ultimately to the instability of the soil. This process can be idealized as a wetting path along which the shear stress and net mean stress keep constant, but the suction decreases over time. However, the instability behavior of unsaturated granular soils along the wetting path has seldom been investigated.
Seepage in unsaturated media is a common phenomenon in geotechnical and geoenvironmental engineering, such as rainfall infiltration into slopes (Ng and Shi, Comput Geotech 22:1–28, 1998; Wu et al., Comput Geotech 117, 2020a), water flow through capillary barrier covers (Chen et al., Comput Geotech 118, 2020; Zhan et al., Sci Total Environ 718, 2020), and contamination migration in unsaturated soils (Bai et al., Int J Heat Mass Transf 153, 2020; Wei et al., Migration and transformation of chromium in unsaturated soil during groundwater table fluctuations induced by rainfall. J Hazard Mater, 126,229, 2021.).
In this chapter, the hydraulic properties of the five design soils listed in Table 2.2 are investigated. The SWCCs were measured in the laboratory using the newly developed low suction SWCC device (Fig. 4.2) and three types’ commercial available devices (i.e., Fredlund SWCC device, Model 1600 pressure plate extractor, and WP4 dewpoint potentiometer device). The soil hydraulic conductivity functions (SHCFs) were measured using the wetting front advancing column tests as described in Chap. 4.
Colluvial soils are widely distributed on natural terrains. Shallow-seated failures with sliding depths varying between 0.5 and 3.0 m are the main failure mode in colluvial soil deposits during rainstorms. The corresponding confining stresses are in a low range between 5 and 25 kPa. It is pertinent to study the behavior of loose, coarse, widely-graded colluvial soils under very low confining pressures to provide better understanding of shallow-seated failures in coarse-grained soils.
The microporosity structure of soil provides important information on the shear strength, compressibility, hydraulic conductivity, and soil–water characteristics of the soil. The soil microporosity structure changes with stress state, transfer of water and air, temperature fluctuations, long-term gravimetric actions, and weathering. To investigate the formation of a microporosity structure during compaction, the evolution of microporosity structure after saturation, and the variation of microporosity structure during wetting–drying, scanning electron microscopy (SEM) was used to characterize the soil surface structure directly, and mercury intrusion porosimetry (MIP) was used to quantify the soil pore-size distribution (PSD).
Energy recovery from carbonaceous solid waste has great potential for waste management and clean sustainable energy production. In this study, incorporating co-hydrothermal carbonization of food waste digestate to improve the gasification of wood waste hydrochar was novelly proposed. Based on the metal compositions and surface properties, the gasification characteristics of the hydrochar were investigated at different temperatures using a thermogravimetric analyzer (TGA). The results indicated that the hydrochar prepared by co-hydrothermal carbonization had abundant surface functional groups and metal components such as calcium (up to 124.25 mg g⁻¹). The addition of food waste digestate significantly improved the gasification activity (up to 7.2 folds at 900 °C) of the hydrochar and reduced the gasification reaction time. Furthermore, the gasification activity of hydrochar was positively correlated with the metal composition content. Both volumetric and grain models showed good fitting effects, and the apparent activation energy of hydrochar gasification for both models was in the range of 121.03–201.37 kJ mol⁻¹. This novel pathway advocated here for the efficient co-conversion of solid waste provides a new perspective for the large-scale utilization of solid waste.
Polyethylene terephthalate (PET) plastic-waste-derived activated carbons have recently been developed and exhibit excellent CO 2 adsorption uptake. However, the CO 2-adsorption performance of such recycled materials has only been considered on a basic characterization level and has not yet been evaluated in carbon capture cycles, thereby making biased analyses inevitable. Consequently, a whole chain including the material, process, and cycle is essential for comprehensively analyzing and evaluating novel CO 2 adsorbents. Therefore, in this study, various CO 2-capture cycles using PET plastic-waste-derived activated carbon adsorbents were numerically simulated, the cyclic CO 2-adsorption performances were evaluated, and the application scenario was optimized. A methodology for evaluating the cyclic CO 2-adsorption performance of PET plastic-waste-derived activated carbon was proposed for CO 2 capture. The results suggested that the temperature/vacuum swing adsorption cycle was superior and that its maximum exergy efficiency reached 32.90%.
Water pollution is continuously raising concern around the world. The uncontrolled and massive discharge of waste components from domestic and various industrial sectors lead to the declining of water quality, and thus impair the aquatic and human health. Among the water pollutants, heavy metals and organic compounds are two major classes of hazardous pollutants present in the water environment, and they typically co-exist specially in industrial wastewater. Semiconductor photocatalysis has been arose as an effective method for water pollutant treatment and also known as green technology due to its cleanliness and sustainability. This chapter is designed to focus on the usability of aerogels as photocatalysts, in order to remove organic and inorganic pollutants from water. Aerogels are three dimensional porous materials, and are known as one of the most considerable adsorbents, because of their special characteristics such low density, high porosity, large surface area and self-supporting configuration. All of these features of aerogels certainly outperform those of conventional photocatalytic materials. Various synthesis methods and classification of aerogel photocatalysts are presented in detail. Furthermore, the potential of aerogels for photocatalytic removal of various organic and inorganic contaminants is presented with possible generalized mechanisms. Aerogels may encounter various challenges and their use is still having a long way to ensure for mature practicing. In the end the challenges associated with aerogel photocatalysis of pollutant and forthcoming outlook are summarized in order to improve their specific potential and successful field application in future.
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