Insights into the hydrolysis/alcoholysis/ammonolysis mechanisms of ethylene naphthalate dimer using density functional theory (DFT) method.

Hydrolysis, alcoholysis and ammonolysis are viable routes for the efficient degradation and recycling of polyethylene naphthalate (PEN) plastic waste. Various possible hydrolysis/alcoholysis/ammonolysis reaction pathways for the degradation mechanism of the ethylene naphthalate dimer were investigated using the density functional theory (DFT) B3P86/6-31++G(d,p). To determine the thermodynamic and kinetic parameters, geometric structure optimization and frequency calculation were performed on a range of intermediates, transition states, and products associated with the reaction. The calculation results show that the highest energy barrier of the main element reaction step in hydrolysis is about 169.0 kJ/mol, the lowest is about 151.0 kJ/mol for ammonolysis, and the second is about 155.0 kJ/mol for alcoholysis. The main hydrolysis products of the ethylene naphthalate dimer are 2,6-naphthalenedicarboxylic acid and ethylene glycol; the main products of alcoholysis are dimethyl naphthalene-2,6-dicarboxylate and ethylene glycol, and the main products of ammonolysis are naphthalene-2,6-dicarboxamide and ethylene glycol. Furthermore, in the process of ethylene naphthalate dimer hydrolysis/alcoholysis/ammonolysis, the decomposition reaction in the NH3 atmosphere is better than that in methanol, and the reaction in CH3OH is better than that in the H2O molecular environment, and the increase in reaction temperature can increase its spontaneity. Our study presents the molecular mechanism of PEN hydrolysis/alcoholysis/ammonolysis and provides a reference for studying the degradation of other plastic wastes.

PCDHA9 as a candidate gene for amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease. To identify additional genetic factors, we analyzed exome sequences in a large cohort of Chinese ALS patients and found a homozygous variant (p.L700P) in PCDHA9 in three unrelated patients. We generated Pcdhα9 mutant mice harboring either orthologous point mutation or deletion mutation. These mice develop progressive spinal motor loss, muscle atrophy, and structural/functional abnormalities of the neuromuscular junction, leading to paralysis and early lethality. TDP-43 pathology is detected in the spinal motor neurons of aged mutant mice. Mechanistically, we demonstrate that Pcdha9 mutation causes aberrant activation of FAK and PYK2 in aging spinal cord, and dramatically reduced NKA-α1 expression in motor neurons. Our single nucleus multi-omics analysis reveals disturbed signaling involved in cell adhesion, ion transport, synapse organization, and neuronal survival in aged mutant mice. Together, our results present PCDHA9 as a potential ALS gene and provide insights into its pathogenesis.

Preparation of PCL/lecithin/bacteriocin CAMT6 antimicrobial and antioxidant nanofiber films using emulsion electrospinning: Characteristics and application in chilled salmon preservation.

Multi-functional packaging materials are an important development for food preservation. Emulsion electrospinning is a novel and simple method that can be used to prepare multi-functional packaging materials, which can effectively protect the loaded active substances during the preparation process. In this study, PCL/lecithin/bacteriocin CAMT6 nanofiber films with antimicrobial and antioxidant activity were prepared by emulsion electrostatic spinning. The morphology and homogeneity of the prepared nanofibrous membranes could be improved by optimising the formulation of the emulsion for electrospinning. Analytical testing of the prepared nanofiber films revealed that the nanofibers had a core-shell structure, with bacteriocin CAMT6 effectively encapsulated in the core layer and the PCL and phospholipids homogeneously mixed to form the shell layer. Additionally, the nanofiber films had acceptable tensile properties and water absorption capacity. In chilled salmon meat, the nanofiber film effectively inhibited the growth of bacteria, slowed the oxidation of oil and slowed water loss, which was a good protective effect. This study provides a reference for the encapsulation application of food-active packaging materials and bacteriocins.

Molecular Characteristics and Formation Mechanisms of Unknown Ozonation Byproducts during the Treatment of Flocculated Nanofiltration Leachate Concentrates Using O3 and UV/O3 Processes.

Both ozone (O3) and UV/O3 treatment processes can effectively remove organic matter in the flocculated membrane filtration concentrate from landfill leachate, but the ozonation byproducts (OBPs) generated in the processes remain unknown. Using electrospray ionization-coupled Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS), this study investigated the molecular characteristics of unknown OBPs and their formation mechanisms during the treatment of flocculated nanofiltration concentrate (FNFC) using the O3 and UV/O3 processes. The results showed that after being treated by the O3 and UV/O3 processes, the average value of the oxygen-to-carbon ratio (O/Cavg) in the FNFC organic matter increased substantially from 0.49 to 0.61-0.64 and 0.63-0.71, respectively, with an O3 dosage of 13.4-54.4 mg/min. The main OBPs were CHO and CHON compounds, which were mainly produced through oxygenation (+O2/+O3 and -H2+O2), oxidative deamination (-NH3+O2), decyclopropyl (-C3H4), and deisopropyl (-C3H6) reactions. The hydroxyl radical (•OH) can intensify these reactions, resulting in an abundance of OBPs with a high oxidation degree and low molecular weight. OBPs at five m/z values were fragmented and analyzed with tandem mass spectrometry, and abundant hydroxyl groups, carboxyl groups, and carbonyl groups were tentatively identified, presenting a potential toxicity to aquatic organisms. Due to the high molecular diversity of the OBPs in FNFC, their lower ΔGCoxo compared to natural fulvic acid, and potential toxicity, their impact on the water environment should be given more attention.

Molecular comparison of organic matter removal from shale gas flowback wastewater: Ozonation versus Fenton process.

Shale gas extraction process generates a large amount of shale gas flowback wastewater (SGFW) containing refractory organic compounds, which can pose serious environmental threats if not properly treated. However, the extremely complex compositions of organics in SGFW are still unknown and their transformation pathways in O3- and •OH-dominated systems are not well recognized, which restrain the selection of treatment technology and optimization of operational parameters. The removal characteristics and reaction mechanism of dissolved organic matter (DOM) in SGFW treated by ozonation and Fenton processes were comparatively investigated using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. The results showed that both processes could degrade low-oxygen highly unsaturated and phenolic organics, polyphenolics and polycyclic aromatics, and transform them into aliphatic organics and high-oxygen highly unsaturated and phenolic organics. With increasing action of reactive oxygen species (O3 for ozonation and •OH for Fenton process), the degradation products (mainly aliphatic organics) increased during ozonation. However, in Fenton process, a wider range of DOM was removed without aliphatic organics accumulation. The degradation mechanisms of DOM during ozonation and Fenton processes included oxygen addition reactions (+3O, +H2O2, and +2O) as dominant pathways. However, ozonation showed more violent oxygenation, hydroxylation, and carboxylation, while Fenton process presented more violent chain-breaking reactions. These results revealed the selective oxidation of ozone and nonselective oxidation of •OH during SGFW treatment, and provided theoretical support for selecting SGFW treatment approaches.

Molecular-level transformation of refractory organic matter during flocculation-ultraviolet/peroxymonosulfate treatment of MBR-treated landfill leachate.

Refractory organic matter in membrane bioreactor effluent resulting from landfill leachate treatment has a complex composition. This paper identified the transformation mechanism of organic matter in a flocculation-ultraviolet (UV)/peroxymonosulfate (PMS) system at the molecular level using electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry. The results showed that the flocculation system was able to remove a large amount of dissolved organic matter (DOM) with high oxidation and unsaturation/saturation. UV radiation displayed a relatively strong reactivity for DOM with an electron-rich structure, which it can transform into DOM with lower aromaticity through photolysis and photosensitivity, although the effectiveness of the transformation was poor. In comparison, due to the action of reactive oxygen species, the UV/PMS system can enable reactions such as demethylation, dehydrogenation, decarboxylation, dehydroxylation, ring cleavage, and decarbonylation. It can remove approximately 60% quantity of the total DOM and produce DOM featuring a higher degree of oxidation and saturation than that of the UV system alone. The results showed that the UV/PMS system was a complementary of flocculation in DOM removal from the membrane bioreactor effluent, while the system also resulted in a large number of sulfuric compounds; thus, requiring further evaluation of its ecological effects.

Preparation, characterization and application of bacteriocin CAMT6 nanoliposomes using resveratrol as a novel stabilizer.

Nanoliposomes are ideal nanocarriers for encapsulated active compounds used in the food industry as they provide stability and controlled release. However, cholesterol may pose risks in large intake, which is the commonly-used nanoliposome stabilizers. In this study, resveratrol was used instead of cholesterol as a novel nanoliposome stabilizer to construct a resveratrol blank liposome (RBL) system. The RBL system was used to protect the bacteriocin CAMT6 to create bacteriocin-loaded nanoliposomes (BLLs). The RBLs and BLLs had favourable particle sizes (172.71 nm and 150.47 nm), polydispersity index (PDI) values (0.150 and 0.120) and zeta potentials (-41.54 mV and -43.53 mV, respectively). According to Differential scanning colourimetry (DSC) and X-ray diffraction (XRD) analyses, resveratrol altered the structure of the phospholipid layer. The phospholipid layers of the RBLs and BLLs had higher mobility when resveratrol was used as a stabilizer instead of cholesterol. Structurally, resveratrol was inserted egg yolk lecithin to constitute an RBL. CAMT6 was loaded in BLLs with spherical and shell-core structures. The BLL encapsulation efficiency was 97.32 % and exhibited three release phases, with the release rates reaching 62 %. In experiments with milk, the BLLs effectively protected the anti-Listeria activity of CAMT6. In summary, resveratrol is a suitable nanoliposome stabilizer and the proposed RBL system is an excellent way to improve the stability of water-soluble preservatives, such as bacteriocins, in complex food environments.

Enhanced performance and mechanism of the combined process of ozonation and a semiaerobic aged refuse biofilter for mature landfill leachate treatment.

A semiaerobic aged refuse biofilter (SAARB) can effectively treat mature landfill leachate (ML), but prolonged operation can lead to the enrichment of pollutants in the biofilter, resulting in severely degraded treatment performance. In this study, we constructed a combination process of ozonation and a SAARB to treat ML based on the principles of selective oxidation of aromatic organics by ozone and the preference of microorganisms for ozonation products. The results showed that the removal of organic and nitrogen pollutants became extremely poor after long-term treatment of ML using the SAARB alone. The decrease of chemical oxygen demand (COD), light absorbance at 254 nm (UV254), NH4+, and total nitrogen (TN) improved significantly after recirculating the ozonated ML effluent (OLE) into the SAARB, and the removal extents increased significantly to 63.59% (COD), 26.14% (UV254), 92.85% (NH4+), and 52.04% (TN), respectively. In addition, the recirculation of OLE enhanced the complete denitrification and tolerance to high NH4+ loading by the SAARB. An analysis of the community composition of 16S_bacteria and ammonia oxidation bacteria (AOB) showed that long-term treatment of ML using the SAARB alone had difficulty enriching the dominant functional bacteria. In the OLE recirculation stage, environmental factors-such as influent organic matter species and concentration, nitrogen pollutant concentration, and pH-were changed to influence the community composition of 16S_bacteria and AOB and enrich functional bacteria (e.g., Truepera, Luteibacter, and Nitrosospira). Therefore, ozonation combined with a SAARB can remove organic and nitrogen pollutants more effectively. In particular, this can be used to solve the problem of inefficient total nitrogen removal using the SAARB alone. This study provides a theoretical reference for the efficient and stable operation of biological processes when treating ML.

Regional distribution, properties, treatment technologies, and resource utilization of oil-based drilling cuttings: A review.

Oil-based drilling cuttings (OBDC) are hazardous wastes produced during the extensive use of oil-based drilling mud in oil and gas exploration and development. They have strong mutagenic, carcinogenic, and teratogenic effects and need to be properly disposed of to avoid damaging the natural environment. This paper reviews the recent research progress on the regional distribution, properties, treatment technologies, and resource utilization of OBDC. The advantages and disadvantages of different technologies for removing petroleum pollutants from OBDC were comprehensively analyzed, and required future developments in treatment technologies were proposed.

Effect of Wax Composition and Shear Force on Wax Aggregation Behavior in Crude Oil: A Molecular Dynamics Simulation Study.

To explore the influence of different wax components and the shear effect exerted by the pump and pipe wall in the process of crude oil pipeline transportation on the microbehavior of wax aggregation in crude oil at low temperatures, molecular dynamics models of binary and multivariate systems of crude oil with different wax components are established in this paper. The simulation results are compared with the existing experimental results and the NIST database to verify the rationality and accuracy of the models. By using the established binary model to simulate four crude oil systems containing different wax components, it can be found that the longer the wax molecular chain, the more easily the wax molecules aggregate. The influence of temperature on the aggregation process of wax molecules with different chain lengths is also studied. The lower the temperature, the greater the difference in wax molecular aggregation degree caused by the difference in molecular chain length. Nonequilibrium molecular dynamics is used to simulate the shear process of a multivariate system of crude oil, and the micromechanisms of the shear effect on the aggregation process of wax molecules are studied. Shearing can destroy the stable structure of crude oil, resulting in the orientation and conformational transformation of wax molecules, and obtaining the region of wax molecules sensitive to temperature and shear effects, the temperatures of which are below the wax precipitation point and the shear rate of which is lower than the maximum shear rate to prevent the molecular structure from being destroyed. At the same time, the sensitivity of wax components with different chain lengths to the shear effect is studied. The research results provide theoretical guidance for ensuring the safe and economic operation of waxy crude oil production.

Single-cell landscape reveals active cell subtypes and their interaction in the tumor microenvironment of gastric cancer.

Background: Gastric cancer remains the third most common cause of cancer-related death worldwide. The development of novel therapeutic strategies for gastric cancer requires a deep understanding of the tumor cells and microenvironment of gastric cancer. Methods: We performed the single-cell RNA sequencing (scRNA-seq) on nine untreated non-metastatic gastric cancer patients. The transcriptomic atlas and ligand-receptor-based intercellular communication networks of the single cells were characterized. Results: Here, we profiled the transcriptomes of 47,304 cells from nine patients with gastric cancer. Tregs cells were significantly enriched in the gastric tumor tissues with increased expression of immune suppression related genes, which suggest a more immunosuppressive microenvironment. We also observed the absence of separate exhausted CD8+ T cell cluster, and the low expression level of exhaustion markers PDCD1, CTLA4, HAVCR2, LAG-3, and TIGIT in those specific cells. These may serve as molecular-level evidence for the limited benefit of immunotherapy among gastric cancer patients. In addition, we found ACKR1 specifically expressed in tumor endothelial cells, associated with poor prognosis in the cohort data and potentially provided a novel target of gastric cancer treatment. Furthermore, the tight interaction between endothelial cells and fibroblast implied the important roles of fibroblast in tumor angiogenesis and the maintenance of tumor vasculature. Conclusions: In conclusion, this single-cell atlas provide understanding the cellular heterogeneity from molecular level in gastric cancer and will serve as a valuable resource for developing innovative early and companion diagnostics, as well as discovering novel targeted therapies for gastric cancer.

Molecular insights into the transformation of refractory organic matter in landfill leachate nanofiltration concentrates during a flocculation and O3/H2O2 treatment.

During leachate treatment, molecular information regarding the completely removed, partially removed, less-reactive, increased, and produced parts of dissolved organic matter (DOM) remains unknown. This study applied ESI FT-ICR MS to investigate the transformation characteristics of leachate nanofiltration concentrate (NFC) DOM during a combined flocculation-O3/H2O2 process. The NFC contained 5069 compounds in four main classes (CHO, CHON, CHOS, and CHONS compounds). The DOM number decreased to 4489 during flocculation and to 2903 after the O3/H2O2 process. During flocculation, the completely and partially removed DOM was mainly low-oxygen unsaturated and phenolic compounds. Saturated DOM was produced and remained in the flocculated effluent. During the O3/H2O2 process, the completely and partially removed DOM were mainly low-oxygen unsaturated and phenolic compounds that were mainly in a reduced state. Flocculation can remove many (condensed) aromatic compounds, and methylation and hydrogenation reactions occurred during flocculation. In the O3/H2O2 process, dearomatization, demethylation, carboxylation, and carbonylation reactions further achieved the degradation of DOM that was resistant to flocculation. Overall, the combined flocculation-O3/H2O2 process collectively eliminated a broader range of DOM than the single processes could achieve. The results of this study provide an in-depth understanding of DOM transformation in an NFC treatment.

Polarized light compass decoding.

The brains of some insects can encode and decode polarization information and obtain heading angle information. Referring to the encoding ability of insects, exponential function encoding is designed to improve the stability of the polarized light compass artificial neural network. However, in the decoding process, only neurons with the largest activation degree are used for decoding (maximum value decoding), so the heading information contained in other neurons is not used. Therefore, average value decoding (AVD) and weighted AVD are proposed to use the heading information contained in multiple neurons to determine the heading. In addition, concerning the phenomenon of threshold activation of insect neurons, threshold value decoding (TVD) and weighted TVD are proposed, which can effectively eliminate the interference of neurons with low activation. Moreover, this paper proposes to improve the heading determination accuracy of the artificial neural network through pre-training. The simulation and experimental results show that the new, to the best of our knowledge, decoding methods and pre-training can effectively improve the heading determination accuracy of the artificial neural network.

The molecular differences of young and mature landfill leachates: Molecular composition, chemical property, and structural characteristic.

Landfill leachate is a highly contaminated and complex organic wastewater. It can be categorized into young (YL) and mature leachate (ML) based on the landfill age, with significant differences in the composition of organic matter, resulting from the significant differences in humification degree. To compare the organic composition of YL and ML, ESI FT-ICR MS was applied to systematically investigate their molecular composition, chemical properties, and structural characteristics. The molecular weight of YL organics was lower than that of ML organics. In addition, O/C and H/C distributions of YL and ML organics were significantly different. YL mainly consisted of CHO compounds and aliphatic compounds. ML mainly consisted of CHON compounds and high oxygen highly unsaturated and phenolic compounds. The unsaturation degree of YL organics was expressed by carbon double bond equivalents ((DBE-C)/C = -0.0336) and was not significantly different from that of ML (-0.0241), but nominal oxidation state of carbon (NOSC = -0.8010) and aromaticity (AImod = 0.1254) of YL were significantly lower than of ML (NOSC = -0.0692; AImod = 0.2464). In addition, YL and ML organics were rich in functional groups, but the YL organics contained more straight-chain structures. The ML organics contained fewer straight-chain structures, a larger number of benzene-ring structures, and more oxygen-containing functional groups. The more complex structural properties of ML organics may be the result of the transformation of YL organics after a long series of reactions, including electrocyclization, decarboxylation, and hydrogen abstraction reactions, which eventually increased the humification degree of leachate organic matter.

Microbial characteristics of the leachate contaminated soil of an informal landfill site.

Because informal landfills are not constructed in a regulated manner, they will inevitably become a source of leachate pollution to the surrounding environment over time. Microbes are an important part of the soil system, playing a vital role in maintaining the normal functionality of soil. This study investigated the microbial composition and co-occurrence pattern in the leachate contaminated soil of an informal landfill site. The landfill leachate underwent horizontal and vertical migration through the contaminated soil, resulting in significant differences in the microbial compositions of horizontal surface soil (CS) and vertical subsurface soil (DS and ES) compared to uncontaminated soil (S). The microbial diversity of CS, DS, and ES was lower than that of S. Due to the migration of landfill leachate, the microbial composition of the surface soil was substantially changed. The dominant phyla in S included Proteobacteria (26.88%), Chloroflexi (23.68%), Actinobacteroita (17.36%), and Acidobacteroita (16.86%), but in contaminated soils, Firmicutes (35.27-86.68%) were the dominant bacteria. A network analysis indicated that Bacilli, Clostridia, and Thermacetogeniazai of the Firmicutes were the keystone taxa and played a vital role in maintaining the stability of the soil ecosystem. A functional annotation of prokaryotic taxa (FAPROTAX) analysis showed that the microbes involved in the C-, N-, and S-cycles in contaminated soil were significantly different to those in uncontaminated soil. The proportion of (aerobic)-chemoheterotrophy and cellulolysis functional communities in contaminated soils was significantly reduced, while there was an increase in functional communities, such as anammox and denitrification, which are not conducive to soil nitrogen fixation. This negatively affected the maintenance of normal soil ecological functions. This study identified the microbial characteristics in leachate contaminated soil and the results will be beneficial for the remediation of contaminated soil in informal landfill sites.

Novel strategy for controlling colloidal instability during the flocculation pretreatment of landfill leachate.

Flocculation is an economical and effective pretreatment technology for landfill leachate. An iron salt flocculant is often used in landfill leachate pretreatment, but the flocs that are formed are affected by the operation sequence, which subsquently influences flocculation. This study selected three representative landfill leachates (i.e., mature landfill leachate (MLL), biologically treated landfill leachate (BTL), and nanofiltration concentrate leachate (NFCL)). The effect of different operation modes on the removal of organic matter from landfill leachate by flocculation was studied, and a strategy to control colloidal instability is put forward. The results revealed that adjusting the pH value to 9 using NaOH changes the zeta potential of leachate when the leachate and sludge are not separated, which affects electric neutralization in flocculation and colloidal stability. Furthermore, a part of the collected organic matter is released to the leachate again, leading to a decrease in the flocculation pretreatment effect. In this improved flocculation process, the leachate and sludge are first separated, and the pH value of the system is then adjusted to 9. The effect of OH- on electric neutralization is avoided and the remaining Fe3+ can further remove organic matter from leachates. Finally, the UV254 removal efficiencies of MLL, BTL, and NFCL increased by 20.38%, 28.67%, and 22.67%, respectively. In a full-scale application, i.e., an NFCL treatment facility, the UV254 removal efficiency during long-term operation reached 87.50%. Therefore, the colloid instability control strategy this study proposes can provide theoretical and engineering references for the flocculation pretreatment of landfill leachate.

Genetic, clinical and neuroimaging profiles of sporadic and autosomal recessive hereditary spastic paraplegia cases in Chinese.

Spastic paraplegias (SPGs) are a group of clinically and genetically heterogeneous neurodegenerative diseases. Mutations in 78 genes have been identified in autosomal dominant hereditary SPG (AD-HSP) and autosomal recessive hereditary SPG (AR-HSP). Compared to familial HSP, much less is known about the genetic and clinical profiles of sporadic SPGs. In this study, we have screened mutations for 18 sporadic SPGs or AR-HSP patients (mainly Northern Chinese) by whole-exome sequencing. We identified 12 mutations in five genes in 9 (50%) patients, including 9 novel ones: SPG5A/CYP7B1 (c.851C > A; c.122 + 2 T > G), SPG11/KIAA1840 (c.1735 + 3_ 1735 + 6del AAGT); SPG7/SPG7 (c.1454G > A; c.1892_ 1906dup GAGGACGGGCCTCGG); SPG39/PNPLA6 (c.1591G > A; c. 2990C > T); SPG15/ ZFYVE26 (c. 4804C > T; c. 4278 G > A). Among all the mutations, 7 were detected in the SPG5A and SPG11. Age at onset was significantly younger in cases with mutations (15.45 ± 6.78 years) than those without mutations (25.56 ± 10.90 years) (P = 0.03). Except for two cases with the SPG5A mutations, all cases presented with complicated SPGs. Three cases carrying mutations in SPG7, SPG15, SPG39 showed symptoms and signs of ataxia. One case carrying the homozygous c.259 + 2 T > C mutation in CYP7B1 showed serum parameters indicating liver impairment. Magnetic resonance imaging showed significantly thinned corpus callosum in cases with SPG11 and SPG15, but not in those with SPG5A, SPG7 or SPG39. In contrast, cerebellar atrophy was prominent in the SPG7 and SPG39 cases. These findings expand the spectrum of genetic, clinical and imaging features of sporadic SPG and AR-HSP, and have important implications in genetic counselling, molecular mechanisms and precise diagnosis of the disease.

Filamentous target segmentation of weft micro-CT image based on U-Net.

Textile fabrics inspection is an important part of textile manufacturing industry, more and more new inspections technologies are adopted for the application. Micro CT imaging technology is recently explored for textile material inspection. This paper proposed a method of weft micro-CT image segmentation based on U-Net, by using deep learning theory and X-ray micro-CT nondestructive detection technology to realize automatic segmentation of filamentous objects. Firstly, the weft micro-CT image was obtained by X-ray micro-CT scan, and then the segmentation target was manually divided. A high segmentation accuracy CT image segmentation dataset of textile materials was built for training the network model. Based on the original U-Net, through experimental exploration, the attention mechanism was introduced, and the encoder module, decoder module and loss function module were adjusted, so as to get a good segmentation effect. The experimental results show that the segmentation performance superiority of this proposed algorithm and the Dice similarity coefficient reaches 0.843. The method proposed in this paper provides a direction for the combination of deep learning technology and micro-CT technology in industrial detection.

Greenhouse gas emissions from semi-aerobic bioreactor landfills with different vent-pipe diameters.

The emission patterns of three greenhouse gasses (GHGs), viz. CH4, CO2, and N2O from landfills, were examined on a lab scale. Three simulated semi-aerobic bioreactor landfills (SABL1, SABL2, SABL3), with respective vent-pipe inner diameters (φ) of 25, 50, and 75 mm, were used to investigate their effect on the greenhouse effect (GHE) during the municipal solid waste (MSW) stabilization process. We found that the vent-pipe φ influenced both MSW degradation and GHG emissions, increasing the vent-pipe φ which improved the removal of carbon and nitrogen-based pollutants. The GHG emissions were 364, 356, and 309 kg CO2 equivalents per ton of MSW from the SABL2, SABL1, and SABL3, respectively, during the operation of 465 days. Of the three GHGs, CH4 influenced the GHE the most, contributing 72.53%, 79.17%, and 71.42% in SABL1, SABL2, and SABL3, respectively. In the same sequence, CO2 (14.87%, 14.06%, and 21.9%) and N2O (12.6%, 6.77%, and 6.69%) were the second and third contributors to the GHE, respectively. Considering the rapidly MSW stabilization and the mitigation of GHG emissions, a vent pipe with φ of 75 mm in the SABL column (φ of 800 mm) was suggested. Moreover, the GHG mitigation in the SABL should be implemented by prioritizing CH4 collection and oxidation. The results provided a technical guidance for GHG mitigation in MSW management.

Application of membrane separation technology in the treatment of leachate in China: A review.

To comprehensively investigate the application of membrane separation technology in the treatment of landfill leachate in China, the performance of nearly 200 waste management enterprises of different sizes in China were analyzed, with an emphasis on their scale, regional features, processes, and economic characteristics. It was found that membrane separation technologies, mainly nanofiltration (NF), reverse osmosis (RO), and NF + RO, have been used in China since 2004. The treatment capacity of the two most dominant membrane separation technologies, i.e., NF and RO, were both almost 60,000 m3/d in 2018, and both technologies are widely used in landfills and incineration plants. Their distribution is mainly concentrated in eastern and southwestern China, where the amount of municipal solid waste (MSW) is relatively high and the economy is developing rapidly. Membrane separation technology is the preferred technique for the advanced treatment of leachate because more contaminants can be effectively removed by the technology than by other advanced processes. However, the membrane retentate that is produced using this technology-commonly known as leachate concentrate-is heavily contaminated due to the enrichment of almost all the inorganic anions, heavy metals, and organic matter that remain after bioprocessing. An economic cost analysis revealed that the operating cost of membrane separation technology has stabilized and is between 1.77 USD/m3 and 4.90 USD/m3; electricity consumption is the most expensive cost component. This review describes the current problems with the use of membrane separation technology and recommends strategies and solutions for its future use.