Study on the dynamic response characteristics of lining structures in large-section tunnel blasting using JH-2 model analysis.

The lining structures of tunnels are typically constructed using sprayed or cast concrete materials, and their performance and quality during tunnel excavation and blasting are crucial for the stability and safety of tunnels. Therefore, the safe distance between the lining structure and blasting source should be determined to avoid concrete damage caused by blasting vibrations. In this study, taking the subway tunnel of Danshan Station in Qingdao as an example, the JH-2 model is introduced as the constitutive model of the tunnel blasting simulation, and the JH-2 model parameters of the local surrounding rock are obtained by experiments, and finally the numerical simulation and theoretical verification are carried out to study the safety distance of shotcrete under various safety judgment standards. The results indicate that the JH-2 model can effectively simulate the propagation of stress waves under different media conditions, and the closer the strength parameters and pressure constant of the lining structure are to those of the surrounding rock, the safer the concrete-rock bonding interface. During tunnel blasting construction using the ring blasting method, the peak particle velocity (PPV) of the lining structure increases with an increase in the arch angle. Based on the numerical simulation results, we recommend that concrete lining be constructed at a distance of at least 62 m from the blasting source to avoid damage caused by vibrations. The effect of concrete tensile failure caused by longitudinal stress is much smaller than the damage to the bonding interface caused by the PPV and can be neglected.

Coupling of Electric and Flow Fields to Enhance Ion Transport for Energy-Efficient Electrochemical Tap-Water Softening.

Electrochemical-induced precipitation is a sustainable approach for tap-water softening, but the hardness removal performance and energy efficiency are vastly limited by the ultraslow ion transport and the superlow local HCO3-/Ca2+ ratio compared to the industrial scenarios. To tackle the challenges, we herein report an energy-efficient electrochemical tap-water softening strategy by utilizing an integrated cathode-anode-cathode (CAC) reactor in which the direction of the electric field is reversed to that of the flow field in the upstream cell, while the same in the downstream cell. As a result, the transport of ions, especially HCO3-, is significantly accelerated in the downstream cell under a flow field. The local HCO3-/Ca2+ ratio is increased by 1.5 times, as revealed by the finite element numerical simulation and in situ imaging. In addition, a continuous flow electrochemical system with an integrated CAC reactor is operated for 240 h to soften tap water. Experiments show that a much lower cell voltage (9.24 V decreased) and energy consumption (28% decreased) are obtained. The proposed ion-transport enhancement strategy by coupled electric and flow fields provides a new perspective on developing electrochemical technologies to meet the flexible and economic demand for tap-water softening.

Hierarchical Porous Bimetallic FeMn Metal-Organic Framework Gel for Efficient Activation of Peracetic Acid in Antibiotic Degradation.

Effective techniques for eliminating antibiotics from water environments are in high demand. The peracetic acid (PAA)-based advanced oxidation process has recently drawn increasing attention for its effective antibiotic degrading capability. However, current applications of PAA-based techniques are limited and tend to have unsatisfactory performance. An additional catalyst for PAA activation could provide a promising solution to improve the performance of PAA. Bulky metal-organic framework gels (MOGs) stand out as ideal catalysts for PAA activation owing to their multiple advantages, including large surface areas, high porosity, and hierarchical pore systems. Herein, a bimetallic hierarchical porous structure, i.e., FeMn13BTC, was synthesized through a facile one-pot synthesis method and employed for PAA activation in ofloxacin (OFX) degradation. The optimized FeMn MOG/PAA system exhibited efficient catalytic performance, characterized by 81.85% OFX degradation achieved within 1 h owing to the specific hierarchical structure and synergistic effect between Fe and Mn ions, which greatly exceeded the performance of the only PAA-catalyzed system. Furthermore, the FeMn MOG/PAA system maintained >80% OFX degradation in natural water. Quenching experiments, electron spin resonance spectra, and model molecular degradation revealed that the primary reactive oxygen species responsible for the catalytic effect was R-O•, especially CH3C(=O)OO•, with minor contributions of •OH and 1O2. Overall, introduction of the MOG catalyst strategy for PAA activation achieved high antibiotic degradation performance, establishing a paradigm for the design of heterogeneous hierarchical systems to broaden the scope of catalyzed water treatment applications.

Local O2 concentrating boosts the electro-Fenton process for energy-efficient water remediation.

The electro-Fenton process is a state-of-the-art water treatment technology used to remove organic contaminants. However, the low O2 utilization efficiency (OUE, <1%) and high energy consumption remain the biggest obstacles to practical application. Here, we propose a local O2 concentrating (LOC) approach to increase the OUE by over 11-fold compared to the conventional simple O2 diffusion route. Due to the well-designed molecular structure, the LOC approach enables direct extraction of O2 from the bulk solution to the reaction interface; this eliminates the need to pump O2/air to overcome the sluggish O2 mass transfer and results in high Faradaic efficiencies (~50%) even under natural air diffusion conditions. Long-term operation of a flow-through pilot device indicated that the LOC approach saved more than 65% of the electric energy normally consumed in treating actual industrial wastewater, demonstrating the great potential of this system-level design to boost the electro-Fenton process for energy-efficient water remediation.

Gamma irradiation induced degradation of organic pollutants: Recent advances and future perspective.

Different organic compounds in aquatic bodies have been recognized as an emerging issue in Environmental Chemistry. The gamma irradiation technique, as one of the advanced oxidation techniques, has been widely investigated in past decades as a technique for the degradation of organic molecules, such as dyes, pesticides, and pharmaceuticals, which show high persistence to degradation. This review gives an overview of what has been achieved so far using gamma irradiation for different organic compound degradations giving an explanation of the mechanisms of degradations as well as the corresponding limitations and drawbacks, and the answer to why this technique has not yet widely come to life. Also, a new approach, recently presented in the literature, regards coupling gamma irradiation with other techniques and materials, as the latest trend. A critical evaluation of the most recent advances achieved by coupling gamma irradiation with other methods and/or materials, as well as describing the reaction mechanisms of coupling, that is, additional destabilization of molecules achieved by coupling, emphasizing the advantages of the newly proposed approach. Finally, it was concluded what are the perspectives and future directions towards its commercialization since this technique can contribute to waste minimization i.e. not waste transfer to other media. Summarizing and generalization the model of radiolytic degradation with and without coupling with other techniques can further guide designing a new modular, mobile method that will satisfy all the needs for its wide commercial application.

DNA and RNA Stability of Marine Microalgae in Cold-Stored Sediments and Its Implications in Metabarcoding Analyses.

The ever-increasing applications of metabarcoding analyses for environmental samples demand a well-designed assessment of the stability of DNA and RNA contained in cells that are deposited or buried in marine sediments. We thus conducted a qPCR quantification of the DNA and RNA in the vegetative cells of three microalgae entrapped in facsimile marine sediments and found that >90% of DNA and up to 99% of RNA for all microalgal species were degraded within 60 days at 4 °C. A further examination of the potential interference of the relic DNA of the vegetative cells with resting cyst detection in sediments was performed via a metabarcoding analysis in artificial marine sediments spiked with the vegetative cells of two Kareniaceae dinoflagellates and the resting cysts of another three dinoflagellates. The results demonstrated a dramatic decrease in the relative abundances of the two Kareniaceae dinoflagellates in 120 days, while those of the three resting cysts increased dramatically. Together, our results suggest that a positive detection of microalgae via metabarcoding analysis in DNA or RNA extracted from marine sediments strongly indicates the presence of intact or viable cysts or spores due to the rapid decay of relic DNA/RNA. This study provides a solid basis for the data interpretation of metabarcoding surveys, particularly in resting cyst detection.

A dissipative particle dynamics simulation of controlled loading and responsive release of theranostic agents from reversible crosslinked triblock copolymer vesicles.

To control the transport stability and release efficiency of loaded theranostic drugs in triblock copolymer carriers, the reversible crosslinking ability is of great significance. A molecular level exploration of such a function is needed to extend existing stabilizing and responsive dissociation mechanisms of carriers. Here, dissipative particle dynamics simulations were used to first demonstrate the formation of triblock copolymer vesicular carriers. Chemical crosslinking was used to strengthen the structural stability of the vesicle shell to avoid drug leakage. Reversible decrosslinking along with dissociation of the vesicle and release of loaded drugs were then explored. The structural, energetic and dynamical properties of the system were discussed at the molecular level. The regulation mechanism of drug release patterns was revealed by systematically exploring the effect of intra and intermolecular repulsive interactions. The results indicate that the chemical crosslinking of copolymers enhanced the compactness of the vesicle shell with a strengthened microstructure, increased binding energy, and limited chain migration, thus achieving more stable delivery of drugs. In terms of drug release, we clarified how the pairwise interactions of beads in the solution system affect the responsive dissociation of the vesicle and associated release patterns (speed and amount) of drugs. More efficient delivery and smart release of theranostic drugs are achieved using such reversible crosslinked triblock copolymer vesicles.

Zeolitic imidazolate framework-8/polyaniline nanocomposite-based electrochemical sensor for sensitive detection of imidaclothiz.

Imidaclothiz (IMZ) is a class of neonicotinoid insecticide which can pose potential threat to human health and be frequently detected in water and foods. Herein, a zeolitic imidazolate framework-8/polyaniline (ZIF-8/PANI) nanocomposite has been modified on the surface of glassy carbon electrode (GCE) for the electrochemical determination of IMZ, and the electrochemical detection performance of the modified electrode was investigated by cyclic voltammetry (CV) and square wave voltammetry (SWV). With the large surface area of ZIF-8 and great electric conductivity of PANI, the ZIF-8/PANI-modified electrode showed a high catalytic performance towards IMZ reduction in PBS. Under the optimized conditions, the linear range was from 1.0 × 10-7 to 1.0 × 10-5 mol/L and the limit of detection was as low as 2.5 × 10-8 mol/L (S/N = 3). In addition, the developed sensor displayed high reproducibility, excellent stability, and applicability in real vegetable sample analysis, indicating that the proposed method offered an alternative approach for IMZ residues analysis.

Understanding residents' behaviour intention of recycling plastic waste in a densely populated megacity of emerging economy.

Plastic waste is choking our planet, but the recycling rate is still universally low. Understanding factors affecting recycling behaviours can help address this pressing issue. Taking Dhaka as an example, this study explores the determinants of the intentions to recycle plastic waste. We employed the Theory of Planned Behaviour (TPB) and extended it with two additional variables: Moral Norms, and Perceived sufficiency of knowledge and policy support. Survey data of 577 were collected and analysed using PLS-SEM. The findings suggest attitude, perceived behavioural control, moral norms and subjective norms significantly impact recycling intention, among which moral norms (ß = 0.148, p < 0.05) acts even more strongly than subjective norms (ß = 0.12, p < 0.05). Moreover, low level perception of knowledge and policy support makes people perceive less control over recycling behaviour (ß = 0.188, p < 0.05), but actually reinforce their recycling intention (ß = -0.091, p < 0.1). This study enriches the theoretical discussion of TPB, and contributes to the efforts of encouraging plastic recycling in populated megacity of emerging economy.

Assessing resilience of sustainability to climate change in China's cities.

Achieving sustainability and coping with climate change are the greatest challenges to human survival and harmonious human-nature relationship. However, there is a lack of research on quantifying the resilience of sustainability to climate change over space and time. Here, a quantification method was developed to evaluate resilient performance of sustainability (includes economic, social, and environmental sub-resilient performance and resilient performance index) to climate change, and performed the first demonstration in China's 280 cities. It was found that resilient performance index of China's sustainability to climate change improved from 2005 to 2017, especially in Southwest China, but 6.8 % of cities showed a decreasing trend. With the improvement of the resilient performance index, the synergy degree among economic, social, and environmental sub-resilient performance scores increased. Economic development and sustainability improvement related to a higher but more disparity of the resilient performance index. This study encourages researchers and policymakers worldwide to focus on resilience of sustainability to climate change to help achieve sustained development and prosperity under climate change.

Soft corrugated channel with synergistic exclusive discrimination gating for CO2 recognition in gas mixture.

Developing artificial porous systems with high molecular recognition performance is critical but very challenging to achieve selective uptake of a particular component from a mixture of many similar species, regardless of the size and affinity of these competing species. A porous platform that integrates multiple recognition mechanisms working cooperatively for highly efficient guest identification is desired. Here, we designed a flexible porous coordination polymer (PCP) and realised a corrugated channel system that cooperatively responds to only target gas molecules by taking advantage of its stereochemical shape, location of binding sites, and structural softness. The binding sites and structural deformation act synergistically, exhibiting exclusive discrimination gating (EDG) effect for selective gate-opening adsorption of CO2 over nine similar gas molecules, including N2, CH4, CO, O2, H2, Ar, C2H6, and even higher-affinity gases such as C2H2 and C2H4. Combining in-situ crystallographic experiments with theoretical studies, it is clear that this unparalleled ability to decipher the CO2 molecule is achieved through the coordination of framework dynamics, guest diffusion, and interaction energetics. Furthermore, the gas co-adsorption and breakthrough separation performance render the obtained PCP an efficient adsorbent for CO2 capture from various gas mixtures.

Combined conditioning of inorganic coagulant and polyamine to improve the dewaterability of municipal sludge, minimize dosage and reduce the influence of filtrate.

Efficient dewatering of sludge is necessary for its cost-effective transportation and final disposal. However, the common method of using polyferric sulfate (PFS) and polyacrylamide (PAM) requires a large amount of dosage and produces high iron ion content in the filtrate. This study examined a solution of applying polyamine (PA) coupled with inorganic coagulant PFS. The results demonstrated that using PFS + PA together could achieve the same or similar filtering rates as using PFS + PAM. The capillary suction time (CST) of PFS + PA (89.0 s) was equivalent to that of PFS (75.1 s) and better than that of PA (117.1 s) and raw sludge (RS, 403.8 s). Compared with PFS + PAM, the combination of PFS and PA efficiently removed Fe ions and chemical oxygen demand (COD) in sludge water content, with Fe ions in the sludge filtrate reduced by 97.8% and COD reduced by 78.9%, respectively. By analyzing the basic physicochemical properties of the sludge system, including the synergistic effect of coagulation and flocculation, sludge hydrolysis and flocculation, it indicated that PA + PFS could reduce bound water. These results demonstrated that combining PFS and PA to improve sludge dewatering performance is more beneficial than utilizing a coagulant or flocculant alone, even PFS + PAM.

Food processing industry changes across China regions: The case of flour, rice, oil, and other cereal derivative food.

Faced with the pressure of slowing industrial growth and industrial transformation requirements, it is crucial to analyze the changes and the corresponding driving factors of the food processing industry in China. An analysis using traditional and spatial shift-share models was conducted to decompose the changes in the food processing industry in each region of China from 2009 to 2019 into five effects: national growth effect (NG), industrial mix effect (IM), competitive effect (CE), neighbor-nation competitive effect (NNC), and region-neighbor competitive effect (RNC). Among the five effects from 2009 to 2019, the NG contributed the most to the growth in most regions, indicating that the development of the food processing industry in China was greatly influenced by the industrial base and that China's food processing industry has entered a "growth bottleneck period." During the period 2009-2014 to period 2014-2019, compared to the IM and CE, the influence of spatial spillover effects was stronger and significantly enhanced. Moreover, the IM, CE, NNC, and RNC in most southern regions were stronger than those in most northern regions. Therefore, China's food processing industry needs and is transforming into high-quality development. It is necessary to innovate the mode of development of food processing industry and strengthen interregional exchanges and cooperation.

An all-organic conditioning method to achieve deep dewatering of waste activated sludge and the underlying mechanism.

Among the common treatment/disposal routes of excessive activated sludge from municipal wastewater treatment plant, dewatering process functions as an essential pre-/post-treatment for volume minimization and transportation facilitation. Since inorganic coagulants have long been criticized for their high dosage and solid residue in sludge cake, there is an urgent need for investigations regarding the potential of applying organic chemicals as the conditioner. In this study, combined use of poly dimethyldiallylammonium chloride (PDMD) and tannic acid (TA) were investigated as an all-organic co-conditioning method for sewage sludge pre-treatment. Results showed that this all-organic conditioning strategy can effectively improve the dewaterability of sewage sludge. The capillary suction time reduced from 128.8 s to 23.1 s, and the filtration resistance reduced from 1.24 × 1012 cm/g to 7.38 × 1010 cm/g. The moisture content of dewatered sludge cake decreased to as low as 55.83%, showing the highest dewatering efficiency reported so far. In addition, the combination of PDMD and TA maximized the treating efficiency with very limited consumption of conditioners (added up to 4% of total solid). Based on the physic-chemical and rheological property investigation, it was proposed that the intermediate molecular weight polymer-based flocculation process and the TA agent-based protein precipitation process, could remarkably strengthen the compactness and structure robustness of sludge. In all, this PDMD-TA-based conditioning method suggested practical significance in consideration of its cost-effectiveness and disposal convenience of sludge cake.

Spatiotemporal impacts of climate change and human activities on water resources and ecological sensitivity in the Mekong subregion in Cambodia.

Water resources in the Mekong subregion in Cambodia (MSC) have experienced dramatic changes in past decades, threatening regional ecosystem quality and sustainable development. Thus, it is important to explore the spatiotemporal impacts of climate change and human activities on water resources and ecological sensitivity. This study proposed an effective framework including spatiotemporal analysis of land use/cover change (LUCC) and ecological sensitivity assessment by combining remote sensing (RS) and geographic information system/science (GIS). An optimized feature space and a machine learning classification algorithm were constructed to extract four typical land cover types in the MSC from 1990 to 2020. An ecological sensitivity evaluation system, including four sub-sensitivities calculated by twelve indicators, was then constructed. The results suggest that severe shrinkage of water resources occurred before 2006, decreasing by 21.68%. The correlation between water resources and climate conditions displays a high to low level as human activity becomes involved. A significant spatiotemporal evolutionary pattern of ecological sensitivity was observed under the impact of external interference. Generally, the largest proportion of MSC belongs to the lightly sensitive level, which is mainly concentrated in the lower reaches, with an average of 33.93%. The highly sensitive area with a significant value in ecological protection has a slightly downward trend from 23.72 in 1990 to 22.55% in 2020.

Characterizing the Status of Energetic Metabolism of Dinoflagellate Resting Cysts under Mock Conditions of Marine Sediments via Physiological and Transcriptional Measurements.

Similar to the seeds of higher plants, resting cysts, a non-motile, benthic, and dormant stage in the life history of many dinoflagellate species, play vital roles via germination in the seasonal dynamics and particularly the initiation of harmful algal blooms (HABs) of dinoflagellates. It is thus crucial for resting cysts to balance between the energetic catabolism for viability maintenance and the energy preservation for germination during their dormancy. Despite this importance, studies on how resting cysts of dinoflagellates accomplish energetic metabolism in marine sediment have been virtually absent. In this study, using the cosmopolitan HABs-causing species Scrippsiella acuminata as a representative, we measured the transcriptional activity of the most efficient pathway of the energy catabolism tricarboxylic acid (TCA) cycle, cell viability (via neutral red staining), and the cellular ATP content of resting cysts under a set of mock conditions in marine sediments (e.g., 4 °C, darkness, and anoxia) for a maximum period of one year. Based on the correlation analyses among the expression levels of genes, cyst viability, and ATP content, we revealed that the TCA cycle was still a crucial pathway of energetic catabolism for resting cysts under aerobic conditions, and its expression was elevated at higher temperatures, light irradiation, and the early stage of dormancy. Under anaerobic conditions, however, the TCA cycle pathway ceased expression in resting cysts, as also supported by ATP measurements. Our results have laid a cornerstone for the comprehensive revelation of the energetic metabolism and biochemical processes of dormancy of resting cysts in marine sediments.

Designing polymersomes with inhomogeneous membranes by co-assembly of block copolymers for controlled morphological reversibility.

Polymersomes with inhomogeneous membranes in composition and structure have generated widespread interest for the preparation of functionalized nanocarriers. We propose a simple but versatile strategy to manipulate inhomogeneous subdomains on polymersome membranes by the co-assembly of block copolymer blends with varied molecular architectures and chemistries. Both binary and ternary copolymer blends are considered to construct polymersomes, and the subdomains of the membranes are formed by controlling the difference in the flexibility and rigidity of different blocks. This difference contributes to the formation of disk-like domains (by rigid blocks) and soft domains (by flexible blocks) on the membrane. An interesting effect of this structure is that in response to external stimuli, the soft membrane domain becomes worm-like or porous to "open" the polymersome for matter exchange, while the rigid domain stays undecomposed and acts like an anchor binding all flexible copolymers. Once the external stimuli disappear, all flexible copolymers can be pulled back to restore the original polymersome morphology (i.e., "close" the polymersome). The specific morphological reversibility of hybrid polymersomes holds great potential for practical applications where changeable membrane permeability or shape under environmental stimuli is highly needed.

Hierarchical porous melamine sponge@MIL-101-Fe-NH2 composite as Fenton-like catalyst for efficient and rapid tetracycline hydrochloride removal.

Metal-organic frameworks have been investigated in Fenton-like catalysis for tetracycline hydrochloride degradation, a widely used antibiotic which threatens the growth and health of creatures. However, powder phase and absence of large pores limit the materials' degradation performance and application. In this work, a hierarchical macro-meso-microporous composite melamine sponge@MIL-101-Fe-NH2 was firstly designed and constructed. While the micropores provided plenty of active sites to generate reactive oxygen species, the macropores and mesopores accelerated mass transfer. Besides, MIL-101-Fe-NH2 particles dispersed on melamine sponge individually, exposing more catalytic sites and avoiding inactivation caused by aggregation compared to powder catalysts. Its catalysis performance for tetracycline hydrochloride degradation was evaluated through changing various influence factors like H2O2 concentration, catalyst amount, pH and coexisting ions. Different from the preference of homogenous Fenton catalysts for pH 2-4, the composite displayed the most effective degradation at a subacid environment closer to nature with 77.24% in 30 min. Owing to the synergistic effect of hierarchical porous structure and monodispersed nanoparticles, the composite exhibited faster reaction rate and longer persistence compared to powder MIL-101-Fe-NH2. Easy recycling and less ion leaching made it advantages for practical application. •OH, •O2- and 1O2 active species contributed together to the degradation and two main possible degradation pathways were put forward based on 35 detected intermediates.

Identification of Fenton-like active Cu sites by heteroatom modulation of electronic density.

Developing heterogeneous catalysts with atomically dispersed active sites is vital to boost peroxymonosulfate (PMS) activation for Fenton-like activity, but how to controllably adjust the electronic configuration of metal centers to further improve the activation kinetics still remains a great challenge. Herein, we report a systematic investigation into heteroatom-doped engineering for tuning the electronic structure of Cu-N4 sites by integrating electron-deficient boron (B) or electron-rich phosphorus (P) heteroatoms into carbon substrate for PMS activation. The electron-depleted Cu-N4/C-B is found to exhibit the most active oxidation capacity among the prepared Cu-N4 single-atom catalysts, which is at the top rankings of the Cu-based catalysts and is superior to most of the state-of-the-art heterogeneous Fenton-like catalysts. Conversely, the electron-enriched Cu-N4/C-P induces a decrease in PMS activation. Both experimental results and theoretical simulations unravel that the long-range interaction with B atoms decreases the electronic density of Cu active sites and down-shifts the d-band center, and thereby optimizes the adsorption energy for PMS activation. This study provides an approach to finely control the electronic structure of Cu-N4 sites at the atomic level and is expected to guide the design of smart Fenton-like catalysts.