The field of sustainable polymers from renewable feedstocks is a fast-reviving field after the decades-long domination of petroleum-based polymers. Amide-containing polymers exhibit a wide range of ...properties depending on the type of amide (primary, secondary, and tertiary), amide density, and other molecular structural parameters (co-existing groups, molecular weight, and topology). Engineering amide groups into sustainable polymers
via
the "monomer approach" is an industrially proven strategy, while bio-based monomers are of enormous importance to bridge the gap between renewable sources and amide-containing sustainable polymers (AmSPs). This feature article aims at conceptualizing the monomer-design philosophy behind most of the reported AmSPs and is organized by discussing di-functional monomers for step-growth polymerization, cyclic monomers for ring-opening polymerization and amide-containing monomers for chain-growth polymerization. We also give a perspective on AmSPs with respect to monomer design and performance enhancement.
This feature article outlines biobased monomer types and their design philosophy targeting three main polymerization routes towards achieving sustainable polymers with amide groups.
In recent years, e vent- b ased s ocial n etworks (EBSNs), such as Meetup, Eventbrite and Douban, have emerged as a popular new type of social network on which online users can organize and register ...for offline social events. Existing approaches focus mainly on arrangement strategies that include users and events on an EBSN platform under an offline scenario, where all information is known in advance. However, these strategies ignore the importance of the organizer, and the offline scenarios can be impractical since all elements appear dynamically in reality. Therefore, we consider not only the user and event in the EBSN platform under the online scenario but also the importance of the organizer. In this paper, we study the complex dynamic event participant in an EBSN that considers three elements: users, events and organizers. We first formalize the event arrangement problem in the online scenario through e vent a rrangement through t hree- d imensional m atching (EATDM). Then, we propose a straightforward solution of the EATDM problem, a greedy algorithm with a competitive ratio, and further develop a basis solution, a random algorithm. We also propose a threshold-based algorithm and a weighted-threshold algorithm with a tighter competitive ratio. Finally, we verify the validity and practicability of the proposed algorithms on synthetic and real datasets, and we find that the weighted-threshold algorithm performs better than the random algorithm, the greedy algorithm and the threshold-based algorithm in terms of the total utility value.
To reduce methane emissions into the workings of a longwall panel, the mechanisms of gas emissions and migration within the longwall goaf must first be understood. Additionally, high performance ...drainage boreholes must be designed. Many variables affect the goaf gas flow and borehole drainage efficiency, namely the gas release characteristics of gas sources, the heights of caved and fractured zones of the goaf, the location of the drainage borehole and the position of the effective drainage section (the portion of the perforated case and the uncased open hole). This paper illustrates how these variables influence the goaf gas flow patterns and borehole performances through CFD simulations. A permeability model and a gas release curve, which reflect observations from experiments, geomechanical modellings, mine site monitoring and borehole drainage data, were constructed for the mining-disturbed strata and incorporated into the CFD model. The CFD model was calibrated with the actual drainage data from the surface boreholes at a coal mine. Simulation results show that the gas drainage velocities around the perimeter of the panel goaf are higher than in the central goaf, which is consistent with the overlying annular fracture zone model established from CSIRO previous research. Boreholes located within the annular area drew methane at a higher flow rate than those located in the central area, leading to a significant reduction of methane emissions to the ventilation system. Goaf geometry with higher caved and fractured zones has lower pressure and methane concentration but higher gas flow velocity. The location of the effective drainage section of the borehole has significant influence on drainage performance. Boreholes with the bottom end located in the lower region of the fractured zone, (20m above the roof), can draw more methane than those located in the upper region of the fractured zone (70m above the roof) and those located in the caved zone (2m above the roof).
•A 3-D permeability model and gas release model were used to model longwall goaf gas flow.•Flow patterns under different conditions were obtained.•Methane flows first horizontally and then flow down along the annular higher permeability zone.•Boreholes located in the annular area draw higher methane flow rate.•Perforated section of the boreholes located in the range of fractured zone draw more methane.
In underground coal mining operations, gas content in a coal seam is used to assess the risk of coal and gas outbursts. A broadly standard procedure has been adopted to estimate the gas content with ...coal core in the coal mining industry. In soft or friable or geologically complex sections of coal seams, it has proven to be extremely troublesome in taking coal cores as cores can be severely fragmented or sometimes it is simply impossible to core with conventional coring methods due to poor borehole stability, leaving coal cuttings from boreholes as the only practical alternative for sampling. When coal core is replaced with coal cuttings, concerns have been raised about the validity and accuracy of the procedure used for gas content determination with coal core, in particular with respect to the sampling method of coal cuttings and gas content calculation due to faster initial gas desorption rates of coal cuttings. The standard procedure for gas content determination with coal core has been modified to determine gas content of coal with coal cuttings from underground boreholes. This paper describes the modified method and presents and discusses the results when it was trialed in a soft coal seam at Huainan, China.
•A modified method has been developed to determine gas content of coal with coal cuttings from underground boreholes.•Field trial of this method has been carried out with satisfactory results.•The method is applicable to uncorable coal seams (soft, friable or geologically complex seams).
The aim of this study was to analyze the clinical data, discharge rate, and fatality rate of COVID‐19 patients for clinical help. The clinical data of COVID‐19 patients from December 2019 to February ...2020 were retrieved from four databases. We statistically analyzed the clinical symptoms and laboratory results of COVID‐19 patients and explained the discharge rate and fatality rate with a single‐arm meta‐analysis. The available data of 1994 patients in 10 literatures were included in our study. The main clinical symptoms of COVID‐19 patients were fever (88.5%), cough (68.6%), myalgia or fatigue (35.8%), expectoration (28.2%), and dyspnea (21.9%). Minor symptoms include headache or dizziness (12.1%), diarrhea (4.8%), nausea and vomiting (3.9%). The results of the laboratory showed that the lymphocytopenia (64.5%), increase of C‐reactive protein (44.3%), increase of lactic dehydrogenase (28.3%), and leukocytopenia (29.4%) were more common. The results of single‐arm meta‐analysis showed that the male took a larger percentage in the gender distribution of COVID‐19 patients 60% (95% CI 0.54, 0.65), the discharge rate of COVID‐19 patients was 52% (95% CI 0.34,0.70), and the fatality rate was 5% (95% CI 0.01,0.11).
Research Highlights
Our study explored the clinical and epidemiological characteristics of COVID‐19 patients, and proposed the need to focus on other systemic symptoms such as the gastrointestinal tract firstly, which could be of use for clinical work.
More than half of the materials extracted from natural environments eventually accumulate as building material stock (BMS). From a linear‐to‐circular economy perspective, BMS transforms the building ...sector from a virgin material consumer and a waste generator to a future depository of secondary resources. Studies characterizing the amount and distribution of BMS adopt different approaches, but high data requirements restrict their applicability. This research proposes an alternative method for regional BMS quantification. The method leverages the permanent population, electricity consumption, and BMS of a sample city to develop a statistical regression model; then uses it to estimate the BMS of a larger, homogenous region. With relatively low data requirements, the new method is especially applicable in underdeveloped areas where data required for BMS quantification methods are usually unavailable or incomplete. We apply the method to characterize the spatiotemporal evolution of BMS in China's Greater Bay Area. From 2000 to 2021, the total BMS in this region increased from 4.4 to 7.7 billion tonnes, with concrete, brick, and steel accounting for 72.32%, 17.57%, and 4.71% of the total BMS, respectively. The most rapid BMS growth occurred in Guangzhou (from 534.75 to 1277.82 Mt) and Shenzhen (517.80 to 1235.48 Mt). A core–edge BMS accumulation pattern emerged in this area while the BMS peak showed a coast‐to‐inland shift. Future studies can explore generalizing this new method to characterize BMS in other developing regions.
Three-layer structured composite films consisting of a rutile titanium dioxide (TiO2) film, a cuprous oxide (Cu2O) nanofilm, and silver (Ag) particles were successfully prepared through sputtering ...and annealing procedures. The variations in microstructures and photoactive properties of the composite films were investigated by varying the sputtering duration of Cu2O and Ag. The photoelectrode made of the Ag particle/Cu2O/TiO2 composite films exhibited superior photoelectrochemical and photocatalytic properties in comparison with those of the Cu2O/TiO2 bilayer films and pristine TiO2 film. The surface plasmon resonance of Ag particles promotes the photon absorption capacity of the Ag particle/Cu2O/TiO2 composite films. Moreover, the Ag particles on the Cu2O nanolayer act as effective electron traps, thus preventing recombination of photoinduced carriers under irradiation and prolonging the carrier lifetime, thereby increasing the carrier transfer rate. The Ag particle/Cu2O/TiO2 composite film with a surface Ag/(Ag + Cu) atomic ratio of 70.81% exhibits superior photoelectrochemical and photocatalytic properties in comparison with the other Ag particle/Cu2O/TiO2 composite films prepared with different Ag sputtering durations. The suitable Ag particle content is an important factor affecting the photoactive performance of the Ag particle/Cu2O/TiO2 composite film. The scavenger test results demonstrate that the photodegradation mechanism of the Ag particle/Cu2O/TiO2 composite film towards methyl orange solution under irradiation follows a Z-scheme mechanism.
The underlying mechanisms of complement activation in Stargardt disease type 1 (STGD1) and age‐related macular degeneration (AMD) are not fully understood. Overaccumulation of all‐trans‐retinal ...(atRAL) has been proposed as the pathogenic factor in both diseases. By incubating retinal pigment epithelium (RPE) cells with atRAL, we showed that C5b‐9 membrane attack complexes (MACs) were generated mainly through complement alternative pathway. An increase in complement factor B (CFB) expression as well as downregulation of complement regulatory proteins CD46, CD55, CD59, and CFH were observed in RPE cells after atRAL treatment. Furthermore, interleukin‐1β production was provoked in both atRAL‐treated RPE cells and microglia/macrophages. Coincubation of RPE cells with interleukin‐1 receptor antagonist (IL1Ra) and atRAL ameliorated complement activation and downregulated CFB expression by attenuating both p38 and c‐Jun N‐terminal kinase (JNK) signaling pathways. Our findings demonstrate that atRAL induces an autocrine/paracrine IL‐1/IL‐1R signaling to promote complement alternative pathway activation in RPE cells and provide a novel perspective on the pathomechanism of macular degeneration.
When retinal pigment epithelium (RPE) and microglia/macrophages are challenged with all‐trans‐retinal in the subretinal space, the activation of inflammasomes promotes the secretion of mature interleukin‐1β (IL‐1β) and subsequently leads to the formation of sublytic membrane attack complexes (MACs) on the RPE surface. We hypothesize that sublytic MACs assembled on the RPE cell surface create channels to facilitate the secretion of cytokines and chemokines, such as IL‐1β, and thereby generate a self‐propagating vicious program to aggravate chronic inflammation and attract inflammatory cells in the choroid–retinal region.
The wettability of 3 mol% Y2O3-stabilized ZrO2 (3YSZ) by molten Cu can be greatly improved by applying pulsed currents at 1373 K. The improvement was closely related to current polarity and ...influenced by duty cycle and frequency. When the Cu/3YSZ interface was under cathodic condition, the wettability was mainly improved by the formation of substoichiometric ZrO2-δ and metallic Zr at the interface. Increasing duty cycle caused the interface to change from forming protrusions to creating depression. Decreasing frequency further deepened the depression. In the opposite polarity, the adsorption and enrichment of oxygen reduced the solid-liquid and liquid-vacuum interfacial energies, thus improving the wettability. Only bubbles formed at the interface. The larger the duty cycle, the more rapidly bubbles formed and escaped. The effect of frequency at this polarity was weak. Overall, this work provides a novel and effective strategy for tailoring the wettability and interfacial chemistry between zirconia and metals.
Silicon-based cross-coupling has been recognized as one of the most reliable alternatives for constructing carbon-carbon bonds. However, the employment of such reaction as an efficient ring expansion ...strategy for silacycle synthesis is comparatively little known. Herein, we develop the first intermolecular silacyclization strategy involving Pd-catalyzed silicon-based C(sp
2
)-C(sp
3
) cross-coupling. This method allows the modular assembly of a vast array of structurally novel and interesting sila-benzo
b
oxepines with good functional group tolerance. The key to success for this reaction is that silicon atoms have a stronger affinity for oxygen nucleophiles than carbon nucleophiles, and silacyclobutanes (SCBs) have inherent ring-strain-release Lewis acidity.
Herein, we develop the first silacyclization between 2-halophenols and SCBs, which allows the modular assembly of sila-benzo
b
oxepines with good functional group tolerance and can be applied for the late-stage modification of biologically active molecules.
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