Bulk-heterojunction (BHJ) polymer solar cells (PSCs) have attracted attention over the past decades due to their distinct advantages of low cost, light weight, and the suitability for flexible-device fabrications. Despite the remarkable success in improving the efficiency of PSCs, fullerene-based acceptors have shown evident limitations. Accordingly, increased research efforts have been invested in developing non-fullerene acceptors, and great development has been witnessed in this field in recent years. Among all different kinds of BHJ PSCs, all polymer solar cells (all-PSCs) potentially possess the most stable donor-acceptor phase separation morphology, and all-polymer films are expected to boast superior mechanical properties. Yet, the bottle neck of enhancing the power conversion efficiency (PCE) of all-PSCs currently lies in the performance of the polymer acceptors. In the past years, we have been focusing on designing new polymer acceptors using perylenediimide (PDI) as the main building block and studing their performance in all-PSCs. A series of PDI-based polymer acceptors have been synthesized and studied since 2013. Due to the steric hindrance induced by the bay-region substitution, the PDI polymers mostly manifest low crystallinity. Accordingly, by enhancing the conjugation and rigidity of the polymer backbone, and thereby improving the aggregation and crystallization ability of the polymers, increased PCE has been achieved with all-PSC devices. Consistently, experimental evidence has also been collected showing improved morphology of the active layer. As a result of the continued and systematic studies on designing and synthesizing new polymer acceptors, along with the optimization of device fabrication conditions, the best PCE of all-PSC incorporating a PDI polymer acceptor has now been boosted to 8.59%. Very similar PCE values can be obtained from devices fabricated under ambient conditions, proving the high chemo-stability of the active-layer materials. The synthetic methods of these PDI-based polmers and the device fabrication conditions are much more convenient and economical. All these properties are friendly to the large-scale material preparation and device production. 二元或多元聚合物组成的本体异质结具备高度稳定的微相分离形貌，带来潜在的器件寿命和稳定性方面的巨大优势，全聚合物活性层器件因而成为有机太阳能电池的重要发展方向和研究内容.本文系统介绍近年来苝二酰亚胺类聚合物受体的研究进展，以及将这类聚合物受体应用于全聚合物太阳能电池所取得的重要成果.通过多种不同共聚单元结构的设计和筛选、主链和侧链化学结构的调控和优化，获得了一系列性能优越的苝二酰亚胺聚合物受体，这些材料的运用大幅度地提升了全聚合物太阳能电池的能量转化效率.相关的研究数据和结果也为后续酰亚胺类聚合物受体的设计开发、全聚合物本体异质结活性层的形貌特征和光电转化机制的分析和研究，以及全聚合物太阳能电池器件性能的优化和提升提供了良好的实验基础.
A novel composite material which is referred to as activated carbon fibre supported titanate nanotubes (TNTs@ACF) was used for the removal of methylene blue (MB) from water through the combined adsorption and photocatalysis. TNTs@ACF was synthesized through a one-step hydrothermal method, which was composed of the activated carbon fibre as the skeleton and supported titanate nanotubes. TNTs@ACF showed a large surface area of 540.7 m2/g, thus, facilitating adsorption and interaction with MB. TNTs@ACF could first pre-concentrate MB molecules onto the material and then degrade under UV light irradiation. The first-order model simplified from the Langmuir-Hinshelwood (L-H) model can well describe the photodegradation of MB on TNTs@ACF. Moreover, TNTs@ACF could be reused without significant capacity loss by UV light photo-regenerated. The structure and morphology of TNTs@ACF were indicated by TEM, SEM, and EDS, and it is found that TNTs were highly dispersed on the surface of ACF. XRD, FTIR, and XPS analyses of TNTs@ACF before and after the MB photodegradation also indicated the stability of the material. The combined adsorption and photodegradation suggests that TNTs@ACF is an attractive material for maintainable remediation of organic pollution in the environment.
The discovery of complete ammonia oxidizing bacteria (CAOB) capable of performing the two-step nitrification process on their own has fundamentally upended our traditional perception. However, their environmental distribution and ecological significance in driving ammonia oxidation are still urgently awaited to be assessed. In this study, the diversity and abundance of CAOB amoA gene in wastewater treatment plants (WWTPs) were presented taking advantage of a newly designed primer pair specifically targeting CAOB amoA gene. Phylogenetic results demonstrated the novel amoA gene formed a clearly distinct cluster from the canonical amoA and pmoA genes. Among the five well-supported sub-clusters, Nitrospira nitrosa cluster accounted for 94.34% of all the currently retrieved sequences from WWTPs. More importantly, qPCR results demonstrated a remarkably high abundance of CAOB amoA gene, which were up to 182.7-fold more abundant than AOB amoA gene. This study provided new dimension and fundamental basis for future researches towards biogeochemical nitrogen cycle.
Ammonia oxidation, performed by both ammonia oxidizing bacteria (AOB) and archaea (AOA), is an important step for nitrogen removal in constructed wetlands (CWs). However, little is known about the distribution of these ammonia oxidizing organisms in CWs and the associated wetland environmental variables. Their relative importance to nitrification in CWs remains still controversial. The present study investigated the seasonal dynamics of AOA and AOB communities in a free water surface flow CW (FWSF-CW) used to ameliorate the quality of polluted river water. Strong seasonality effects on potential nitrification rate (PNR) and the abundance, richness, diversity and structure of AOA and AOB communities were observed in the river water treatment FWSF-CW. PNR was positively correlated to AOB abundance. AOB (6.76 x 10(5)-6.01 x 10(7) bacterial amoA gene copies per gram dry sed-iment/soil) tended to be much more abundant than AOA (from below quantitative PCR detection limit to 9.62 x 10(6) archaeal amoA gene copies per gram dry sediment/soil). Both AOA and AOB abundance were regulated by the levels of nitrogen, phosphorus and organic carbon. Different wetland environmental variables determined the diversity and structure of AOA and AOB communities. Wetland AOA communities were mainly composed of unknown species and Nitrosopumilus-like organisms, while AOB communities were mainly represented by both Nitrosospira and Nitrosomonas. (C) 2018 Elsevier B.V. All rights reserved.
An up-flow vertical flow constructed wetland (AC-VFCW) filled with ceramsite and 5% external carbon source poly(3-hydroxybutyrate-hydroxyvalerate) (PHBV) as substrate was set for nitrogen removal with micro aeration. Simultaneous nitrification and denitrification process was observed with 90.4% NH4+-N and 92.1% TN removal efficiencies. Nitrification and denitrification genes were both preferentially enriched on the surface of PHBV. Nitrogen transformation along the flow direction showed that NH4+-N was oxidized to NO3–N at the lowermost 10 cm of the substrate and NO3–N gradually degraded over the depth. AmoA gene was more enriched at -10 and -50 cm layers. NirS gene was the dominant functional gene at the bottom layer with the abundance of 2.05 x 10(7) copies g(-1) substrate while nosZ gene was predominantly abundant with 7.51 x 10(6) and 2.64 x 10(6) copies g(-1) substrate at the middle and top layer, respectively, indicating that functional division of dominant nitrogen functional genes forms along the flow direction in AC-VFCW.
Capacitive deionization (CDI) can remove ionic contaminants from water. However, concentrations of background ions in water are usually much higher than target contaminants, and existing CDI electrodes have no designed selectivity toward specific contaminants. In this study, we demonstrate a selective CDI process tailored for removal of SO42- using activated carbon electrodes modified with a thin, quaternary amine functionalized poly(vinyl alcohol) (QPVA) coating containing submicron sized sulfate selective ion exchange resin particles. The resin/QPVA coating exhibited strong selectivity for SO42- at Cl- : SO42- concentration ratios up to 20:1 by enabling preferential transport of SO42- through the coating, but had no negative impact on the electrosorption kinetics when the coating thickness was small. The cationic nature of the coating also significantly improved the charge efficiency and consequently the total salt adsorption capacity of the electrode by 42%. The resin/QPVA coated CDI system was stable, showing highly reproducible performance in more than 50 adsorption and desorption cycles. This work suggests that addition of selective ion exchange resins on the surface of a carbon electrode could be a generally applicable approach to achieve selective removal of target ions in a CDI process.
This paper proposes a new constitutive model for geotechnical materials that consists two basic constitutive functions, the free energy function and the dissipation rate function, within the framework of hyperplastic theory. This free energy function is capable of describing the pressure-dependent elastic behavior of soils. The new constructed dissipation rate function accounts for the frictional mechanism of energy dissipation. Based on this dissipation rate function, the non-associated flow rule can be obtained. Furthermore, the convexity of the yield surface that is derived from the dissipation rate function is proved. Predictions of the behavior of a soil sample using this new constitutive model agree well with triaxial test data under drained and undrained conditions.
This paper proposes a new constitutive model for geotechnical materials that consists two basic constitutive functions, the free energy function and the dissipation rate function, within the framework of hyperplastic theory. This free energy function is capable of describing the pressure-dependent elastic behavior of soils. The new constructed dissipation rate function accounts for the frictional mechanism of energy dissipation. Based on this dissipation rate function, the non-associated flow rule can be obtained. Furthermore, the convexity of the yield surface that is derived from the dissipation rate function is proved. Predictions of the behavior of a soil sample using this new constitutive model agree well with triaxial test data under drained and undrained conditions.
This paper proposes a new constitutive model for geotechnical materials that consists two basic constitutive functions, the free energy function and the dissipation rate function, within the framework of hyperplastic theory. This free energy function is capable of describing the pressure-dependent elastic behavior of soils. The new constructed dissipation rate function accounts for the frictional mechanism of energy dissipation. Based on this dissipation rate function, the non-associated flow rule can be obtained. Furthermore, the convexity of the yield surface that is derived from the dissipation rate function is proved. Predictions of the behavior of a soil sample using this new constitutive model agree well with triaxial test data under drained and undrained conditions.
Polycyclic aromatic hydrocarbons (PAH) are ubiquitous air pollutants associated with negative impacts on growth, development and behavior in children. Source-specific biological markers of PAH exposure are needed for targeting interventions to protect children. Nitro-derivatives of PAH can act as markers of exposure to diesel exhaust, gasoline exhaust, or general combustion sources. Using a novel HPLC-APCI-MS/MS detection method, we examined four hemoglobin (Hb) adducts of nitro-PAH metabolites and the Hb adduct of a benzo[a]pyrene (BaP) metabolite in 22 umbilical cord blood samples. The samples were collected from a birth cohort with comprehensive data on prenatal PAH exposure, including prenatal personal air monitoring and DNA adducts in maternal and umbilical cord blood. Using non-parametric analyses, heat maps, and principal component analysis (PCA), we analyzed the relationship between the five Hb adducts and previous PAH measurements, with each measurement representing a different duration of exposure. We found that Hb adducts derived from several diesel-related nitro-PAHs (2-nitrofluorene and 1-nitropyrene) were significantly correlated (r = 0.77, p
To satisfy the increasingly high demands in many applications of microfluidics, the size of the droplet needs accurate control. In this paper, a level-set method provides a useful method for studying the physical mechanism and potential mechanism of two-phase flow. A detailed three-dimensional numerical simulation of microfluidics was carried out to systematically study the generation of micro-droplets and the effective diameter of droplets with different control parameters such as the flow rate ratio, the continuous phase viscosity, the interfacial tension, and the contact angle. The effect of altering the pressure at the x coordinate of the main channel during the droplet formation was analysed. As the simulation results show, the above control parameters have a great influence on the formation of droplets and the size of the droplet. The effective droplet diameter increases when the flow rate ratio and the interfacial tension increase. It decreases when the continuous phase viscosity and the contact angle increase.