Bioactive species, including reactive oxygen species (ROS, including O
2
&z.rad;
−
, H
2
O
2
, HOCl,
1
O
2
, &z.rad;OH, HOBr,
etc.
), reactive nitrogen species (RNS, including ONOO
−
, NO, NO
2
, ...HNO,
etc.
), reactive sulfur species (RSS, including GSH, Hcy, Cys, H
2
S, H
2
S
n
, SO
2
derivatives,
etc.
), ATP, HCHO, CO and so on, are a highly important category of molecules in living cells. The dynamic fluctuations of these molecules in subcellular microenvironments determine cellular homeostasis, signal conduction, immunity and metabolism. However, their abnormal expressions can cause disorders which are associated with diverse major diseases. Monitoring bioactive molecules in subcellular structures is therefore critical for bioanalysis and related drug discovery. With the emergence of organelle-targeted fluorescent probes, significant progress has been made in subcellular imaging. Among the developed subcellular localization fluorescent tools, ROS, RNS and RSS (RONSS) probes are highly attractive, owing to their potential for revealing the physiological and pathological functions of these highly reactive, interactive and interconvertible molecules during diverse biological events, which are rather significant for advancing our understanding of different life phenomena and exploring new technologies for life regulation. This review mainly illustrates the design principles, detection mechanisms, current challenges, and potential future directions of organelle-targeted fluorescent probes toward RONSS.
The dynamic fluctuations of bioactive species in living cells are associated with numerous physiological and pathological phenomena. The emergence of organelle-targeted fluorescent probes has significantly facilitated our understanding on the biological functions of these species. This review describes the design, applications, challenges and potential directions of organelle-targeted bioactive species probes.
•We investigate impacts of climate variability and human activity on annual flow in the midstream of the Yellow River.•Annual streamflow shows significant decreases from 0.10mm/yr to 1.61mm/yr at ...most stations.•Decreasing precipitation and increasing temperature are detected for the whole study area.•Climate variability has a greater effect on the streamflow decrease in the Beiluo and Yan Rivers.•Human activities accounted for more of the streamflow reduction in the majority of tributaries.
The middle reaches of the Yellow River basin (MRYRB) contribute significantly to the total streamflow and sediment discharge of the Yellow River. Significant changes in streamflow have been detected; these changes result in part from large number of soil and water conservation measures implemented over the past six decades in this area. This study investigates streamflow variations and evaluates the impacts of climate variability and human activity on the mean annual flow in the MRYRB. The non-parametric Mann–Kendall test and Pettitt’s test are applied to characterize the trends and abrupt changes of hydro-climatic variables in the MRYRB. The analysis was performed on streamflow data taken over the period from the 1950s to 2010 at 18 hydrological stations and on precipitation, temperature and potential evapotranspiration (PET) data from 43 climate stations. We find that 16 of these stations recorded significant decreases in annual streamflow, with reduction rates ranging from 0.10mm/yr to 1.61mm/yr over the study period. Precipitation at all of the stations also had negative trends, with changes ranging from −4.7mm/yr to −0.19mm/yr. Temperature increased significantly at most stations, while PET showed a mixed of upward and downward trend. Abrupt changes in streamflow at mainstream stations occurred when large reservoirs were built, while breakpoints of streamflow at tributary stations were mainly driven by the implementation of soil and water conservation measures. We used both Budyko’s curve (a simple water balance model) and linear regression to evaluate the potential impacts of climate variability and human activities on mean annual streamflow. Climate variability has a greater effect on the streamflow reduction in the Beiluo River and Yan River, while human activities accounted for more of the streamflow changes in other tributaries, especially in the northern catchments. In general, human activities, including soil and water conservation projects, the operation of dams and reservoirs, and water consumption, are found to be the dominant factors responsible for the significant decline in the annual streamflow in the MRYRB over the last six decades.
Perovskite solar cells have delivered power conversion efficiency beyond 22% in less than seven years, implying the potential for the paradigm shift of low‐cost photovoltaics with high efficiency and ...low embedded energy. Besides the “perovskite fever,” the development of new hole transport materials (HTM), especially dopant‐free HTMs, is another research hotspot. This is because the currently used HTMs, such as spiro‐OMeTAD derivatives, require additional chemical doping process to ensure sufficient conductivity and proper ionic potential level for efficient hole transport and collection. However, the commonly used dopants are volatile and hygroscopic which not only increase the complexity and cost of device fabrication but also deteriorate the device stability. So far, there have been several reviews on new HTMs, but review or analysis on dopant‐free HTMs is scarce. In this review, all reported dopant‐free HTMs are categorized into four primary different types and lessons will be learned during the separate discussions. The stability test behavior of all the intrinsic HTMs will be evaluated directly. In the end, the correlations between the properties of the intrinsic HTMs and parameters of the devices will be plotted to shed light on the future direction of development of this field.
Chemical dopants inside organic semiconductor are however not chemically bonded to the matrix. Their hydrophilic and mobile nature plays a significant role in the degradation of the perovskite devices. Dopant free HTMs are of great importance for the final application of this new PV technology.
Excessive use of agro-chemicals （such as mineral fertilizers） poses potential risks to soil quality. Application of organic amendments and reduction of inorganic fertilizer are economically feasible ...and environmentally sound approaches to de- velop sustainable agriculture. This study investigated and evaluated the effects of mineral fertilizer reduction and partial substitution of organic amendment on soil fertility and heavy metal content in a 10-season continually planted vegetable field during 2009-2012. The experiment included four treatments： 100% chemical fertilizer （CF100）, 80% chemical fertilizer （CF80）, 60% chemical fertilizer and 20% organic fertilizer （CF60＋OM20）, and 40% chemical fertilizer and 40% organic fertilizer （CF40＋OM40）. Soil nutrients, enzyme activity and heavy metal content were determined. The results showed that single chemical fertilizer reduction （CF80） had no significant effect on soil organic matter content, soil catalase activity and soil heavy metal content, but slightly reduced soil available N, P, K, and soil urease activity, and significantly reduced soil acid phosphatase activity. Compared with CF100, 40 or 60% reduction of chemical fertilizer supplemented with organic fertilizer （CF60＋OM20, CF40＋OM40） significantly increased soil organic matter, soil catalase activity and urease activity especially in last several seasons, but reduced soil available P, K, and soil acid phosphatase activity. In addition, continu- ous application of organic fertilizer resulted in higher accumulation of Zn, Cd, and Cr in soil in the late stage of experiment, which may induce adverse effects on soil health and food safety.
Oxide perovskite materials have a long history of being investigated for thermoelectric applications. Compared to the state-of-the-art tin and lead chalcogenides, these perovskite compounds have ...advantages of low toxicity, eco-friendliness, and high elemental abundance. However, because of low electrical conductivity and high thermal conductivity, the total thermoelectric performance of oxide perovskites is relatively poor. Variety of methods were used to enhance the TE properties of oxide perovskite materials, such as doping, inducing oxygen vacancy, embedding crystal imperfection, and so on. Recently, hybrid perovskite materials started to draw attention for thermoelectric application. Due to the low thermal conductivity and high Seebeck coefficient feature of hybrid perovskites materials, they can be promising thermoelectric materials and hold the potential for the application of wearable energy generators and cooling devices. This mini-review will build a bridge between oxide perovskites and burgeoning hybrid halide perovskites in the research of thermoelectric properties with an aim to further enhance the relevant performance of perovskite-type materials.
Granite petrogenesis is associated with the formation and evolution of continental crust along convergent plate boundaries. While magmatic processes such as partial melting and fractional ...crystallization result in the compositional diversity of granites, the nature of magma sources is related to tectonic settings of granite generation. Although granites consist predominantly of magmatic minerals, they generally contain small amounts of peritectic and residual minerals. This results in the compositional difference between natural granites and experimental melts. In addition to the fractional crystallization of mantle-derived mafic magmas for the generation of granites during accretionary orogeny, a wide range of crustal rocks can be partially melted to form granites in both accretionary and collisional orogens. In the latter case, metasedimentary and metaigneous crustal sources lead to the dichotomy of S- and I-type granites. Geochemically, granites with negative εNd(t) and εHf(t) values are certainly derived from reworking of the ancient crust. On the other hand, granites with positive εNd(t) and εHf(t) values may be produced either by reworking of the juvenile crust or by fractional crystallization of asthenospheric mantle-derived magmas at actively convergent plate boundaries. In this case, major and trace elements may be of use in distinguishing between the crustal and mantle contributions. Granite, migmatite and granulite generally form lithological associations at previously converged plate boundaries, with migmatitic domes as the major component of metamorphic core complexes. Their formation is related to extensional heating subsequent to thinning of the thickened mantle lithosphere. As soon as the thickened lithospheric mantle was foundered into the asthenospheric mantle, it makes the space for asthenospheric upwelling to induce active rifting along the thinned lithosphere. This provides an external heat source for anatectic metamorphism at high thermal gradients, marking the tectonic transition in the property of orogenic systems into the rifting stage. Therefore, the active rifting is spatially and temporally dictated by thinning of the orogenic mantle lithosphere, and its operation is a geodynamic mechanism for crustal anatexis at convergent plate boundaries. Consequently, the lithospheric thickness has a profound effect on crustal anatexis for granitic magmatism, which is considerably later than plate convergence.
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•Partial melting of crustal rocks produces granitic magmas with varying compositions.•Both ancient and juvenile crust underwent partial melting to produce granitic magmas.•Active rifting is a geodynamic mechanism of crustal anatexis in fossil suture zone.•Rifting orogeny is realized by domical uplift of granites and metamorphic core complexes.•The lithospheric thickness has a profound effect on crustal anatexis for granitic magmatism.
The presence of non‐radiative recombination at the perovskite surface/interface limits the overall efficiency of perovskite solar cells (PSCs). Surface passivation has been demonstrated as an ...efficient strategy to suppress such recombination in Si cells. Here, 1‐naphthylmethylamine iodide (NMAI) is judiciously selected to passivate the surface of the perovskite film. In contrast to the popular phenylethylammonium iodide, NMAI post‐treatment primarily leaves NMAI salt on the surface of the perovskite film. The formed NMAI layer not only efficiently decreases the defect‐assisted recombination for chemical passivation, but also retards the charge accumulation of energy level mis‐alignment for vacuum level bending and prevents minority carrier recombination due to the charge‐blocking effect. Consequently, planar PSCs with high efficiency of 21.04% and improved long‐term stability (98.9% of the initial efficiency after 3240 h) are obtained. Moreover, open‐circuit voltage as high as 1.20 V is achieved at the absorption threshold of 1.61 eV, which is among the highest reported values in planar PSCs. This work provides new insights into the passivation mechanisms of organic ammonium salts and suggests future guidelines for developing improved passivation layers.
A unique ammonium salt, 1‐naphthylmethylamine iodide (NMAI) is shown to passivate the surface defects of perovskite, induce upward energy level bending and block electrons at the interface between the perovskite and hole transport layer in perovskite solar cells. These combined effects result in reduced non‐radiative recombination. Hence, more intensified electroluminescence and a champion open‐circuit voltage of 1.20 V are achieved in NMAI‐based devices.
There are only few semiconducting materials that have been shaping the progress of third generation photovoltaic cells as much as perovskites. Although they are deceivingly simple in structure, the ...archetypal AMX 3 -type perovskites have built-in potential for complex and surprising discoveries. Since 2009, a small and somewhat exotic class of perovskites, which are quite different from the common rock-solid oxide perovskite, have turned over a new leaf in solar cell research. Highlighted as one of the major scientific breakthroughs of the year 2013, the power conversion efficiency of the title compound hybrid organic–inorganic perovskite has now exceeded 18%, making it competitive with thin-film PV technology. In this minireview, a brief history of perovskite materials for photovoltaic applications is reported, the current state-of-the-art is distilled and the basic working mechanisms have been discussed. By analyzing the attainable photocurrent and photovoltage, realizing perovskite solar cells with 20% efficiency for a single junction, and 30% for a tandem configuration on a c-Si solar cell would be realistic.
The ensemble effect due to variation of Pd content in Pd−Au alloys have been widely investigated for several important reactions, including CO2 reduction reaction (CO2RR), however, identifying the ...stable Pd arrangements on the alloyed surface and picking out the active sites are still challenging. Here we use a density functional theory (DFT) based machine‐learning (ML) approach to efficiently find the low‐energy configurations of Pd−Au(111) surface alloys and the potentially active sites for CO2RR, fully covering the Pd content from 0 to 100 %. The ML model is actively learning process to improve the predicting accuracy for the configuration formation energy and to find the stable Pd−Au(111) alloyed surfaces, respectively. The local surface properties of adsorption sites are classified into two classes by the K‐means clustering approach, which are closely related to the Pd content on Au surface. The classification is reflected in the variation of adsorption energy of CO and H: In the low Pd content range (0–60 %) the adsorption energies over the surface alloys can be tuned significantly, and in the medium Pd content (37‐68 %), the catalytic activity of surface alloys for CO2RR can be increased by increase the Pd content and attributed to the meta‐stable active site over the surface. Thus, the active site‐dependent reaction mechanism is elucidated based on the ensemble effect, which provides new physical insights to understand the surface‐related properties of catalysts.
The ensemble effect on the CO2 reduction reaction for the Pd@Au catalyst surface was investigated by using density functional theory and machine‐learning (regression and clustering) methods. The active site‐dependent reaction mechanism was found that would attribute to the ensemble effect of Pd over the Au surface.
Bacteria, as the key component of soil ecosystems, participate in nutrient cycling and organic matter decomposition. However, how fertilization regime affects the rhizospheric bacterial community of ...reddish paddy soil remains unclear. Here, a long-term fertilization experiment initiated in 1982 was employed to explore the impacts of different fertilization regimes on physicochemical properties and bacterial communities of reddish paddy rhizospheric soil in Central South China by sequencing the 16S rRNA gene. The results showed that long-term fertilization improved the soil nutrient status and shaped the distinct rhizospheric bacterial communities. Particularly, chemical NPK fertilizers application significantly declined the richness of the bacterial community by 7.32%, whereas the application of manure alone or combined with chemical NPK fertilizers significantly increased the biodiversity of the bacterial community by 1.45%, 1.87% compared with no fertilization, respectively. Moreover, LEfSe indicated that application of chemical NPK fertilizers significantly enhanced the abundances of Verrucomicrobia and Nitrospiraceae, while manure significantly increased the abundances of Deltaproteobacteria and Myxococcales, but the most abundant Actinobacteria and Planctomycetes were detected in the treatment that combined application of manure and chemical NPK fertilizers. Furthermore, canonical correspondence analysis (CCA) and the Mantel test clarified that exchangeable Mg
(E-Mg
), soil organic carbon (SOC) and alkali-hydrolyzable nitrogen (AN) are the key driving factors for shaping bacterial communities in the rhizosphere. Our results suggested that long-term balanced using of manure and chemical fertilizers not only increased organic material pools and nutrient availability but also enhanced the biodiversity of the rhizospheric bacterial community and the abundance of Actinobacteria, which contribute to the sustainable development of agro-ecosystems.
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