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As a sensitive biological indicator, earthworms are widely used to monitor various pollutants of soil and provide an early warning for soil pollution. However, because many indices are involved in the exposure-induced oxidative stress response, practical applications of these indices are quite inconvenient. Therefore, it is appropriate to investigate the key monitoring index for use in early warning and pollution monitoring. Using Eisenia fetida as an experimental model in an indoor simulation experiment, the mathematical modelling of the effect on oxidative stress in earthworms under cadmium (Cd) stress was studied. The test lasted 40 d, with the removal of one earthworm every 10 d. The Cd2+ concentration gradient was set as 0, 1, 10, 20, 100, 200, 400, and 800 mg kg-1 dry weight. The earthworms were divided into two sections from the clitellum for the determination of total protein (TP) and peroxidase (POD), superoxide dismutase (SOD), glutathione-S-transferase (GST), glutathione peroxidase (GPX), catalase (CAT), malondialdehyde (MDA), and acetylcholinesterase (AChE) activities. Results showed that POD was the key index of oxidative stress in head tissues after 10 d of exposure, TP was the key index at 20 d, and POD became the key index again at 30 and 40 d. By contrast, in tail tissues, MDA and SOD were the key indices at an exposure time of 10 d, GPX at 20 d, CAT and TP at 30 d, and POD and MDA at 40 d. These results contribute to establishing a scientific method for ecotoxicological diagnosis and revealing the mechanism of soil Cd toxicity.

Gaussian mixture model (GMM) clustering has been extensively studied due to its effectiveness and efficiency. Though demonstrating promising performance in various applications, it cannot effectively address the absent features among data, which is not uncommon in practical applications. In this article, different from existing approaches that first impute the absence and then perform GMM clustering tasks on the imputed data, we propose to integrate the imputation and GMM clustering into a unified learning procedure. Specifically, the missing data is filled by the result of GMM clustering, and the imputed data is then taken for GMM clustering. These two steps alternatively negotiate with each other to achieve optimum. By this way, the imputed data can best serve for GMM clustering. A two-step alternative algorithm with proved convergence is carefully designed to solve the resultant optimization problem. Extensive experiments have been conducted on eight UCI benchmark datasets, and the results have validated the effectiveness of the proposed algorithm.

Solar-induced fluorescence (SIF) has become a milestone for estimating terrestrial gross primary productivity (GPP) at the global scale, and therefore it is important to understand how the relationship between SIF and GPP varies with environmental stresses and canopy structures. Our study investigated the impact of environmental conditions on the relationship between SIF and GPP at the global scale based on Global Ozone Monitoring Instrument 2 (GOME-2) SIF and Max Planck Institute for Biogeochemistry (MPI-BGC) GPP. GOME-2 SIF had strong correlations with gridded GPP data at instantaneous (R 2 = 0.618, p R 2 = 0.621, p R 2 = 0.512–0.839, p R 2 = 0.142, p R 2 = 0.395, p R 2 > 0.8) were mainly distributed in southern Europe, southern and central Africa, northeastern and central China, North America, India and southern Russia, and the slope had a similar spatial distribution as the coefficients of determination. The relationship between SIF and GPP varied with air temperature (T Air), vapour pressure deficit (VPD) and leaf area index (LAI). The slope of the SIF-GPP relationship had a maximal value when the air temperature ranged between approximately 10°C and 20°C, when the linear relationships between SIF and GPP were also the strongest. Our analysis based on the Soil-Canopy Observation of Photochemistry and Energy fluxes (SCOPE) model also indicated that the SIF-GPP relationship was complex and affected by T Air, VPD and LAI. Our study can improve our understanding of the functional relationship between SIF and GPP and the information contained in remotely sensed SIF.

Background Understanding the mechanisms of crops in response to elevated CO2 concentrations is pivotal to estimating the impacts of climate change on the global agricultural production. Based on earlier results of the “doubling-CO2 concentration” experiments, many current climate models may overestimate the CO2 fertilization effect on crops, and meanwhile, underestimate the potential impacts of future climate change on global agriculture ecosystem when the atmospheric CO2 concentration goes beyond the optimal levels for crop growth. Results This study examined the photosynthetic response of soybean (Glycine max (L.) Merr.) to elevated CO2 concentration associated with changes in leaf structure, non-structural carbohydrates and nitrogen content with environmental growth chambers where the CO2 concentration was controlled at 400, 600, 800, 1000, 1200, 1400, 1600 ppm. We found CO2-induced down-regulation of leaf photosynthesis as evidenced by the consistently declined leaf net photosynthetic rate (A n) with elevated CO2 concentrations. This down-regulation of leaf photosynthesis was evident in biochemical and photochemical processes since the maximum carboxylation rate (V cmax) and the maximum electron transport rate (J max) were dramatically decreased at higher CO2 concentrations exceeding their optimal values of about 600 ppm and 400 ppm, respectively. Moreover, the down-regulation of leaf photosynthesis at high CO2 concentration was partially attributed to the reduced stomatal conductance (G s) as demonstrated by the declines in stomatal density and stomatal area as well as the changes in the spatial distribution pattern of stomata. In addition, the smaller total mesophyll size (palisade and spongy tissues) and the lower nitrogen availability may also contribute to the down-regulation of leaf photosynthesis when soybean subjected to high CO2 concentration environment. Conclusions Down-regulation of leaf photosynthesis associated with the changes in stomatal traits, mesophyll tissue size, non-structural carbohydrates, and nitrogen availability of soybean in response to future high atmospheric CO2 concentration and climate change.

Blueberry (Vaccinium corymbosum L.) is a deciduous flowering shrub, which originates from North America. In recent years, Blueberry has been introduced into subtropical China where featured with high temperature climates. Understanding the thermal endurance ability of different blueberry cultivars is necessary for heat-tolerant cultivars selection and plantation in subtropical China. We conducted a comparative study on six cultivars including ‘Bluecrop’, ‘Duke’, ‘Brigitta’, ‘Gulfcoast’, ‘O’Neal’, and ‘Blue Ridge’ at different temperatures of 25/20, 30/25, 35/30, or 40/35℃ (day/night) to examine the changes of growth, physiology, and biochemistry in blueberry plants. We found that the biomass of blueberry plants generally shared bell-shaped curves with increasing growth temperatures, indicating different optimal growth temperature for each cultivar. Meanwhile, the six blueberry cultivars also shared different heat endurance abilities that the appearances of ‘Duke’ and ‘Blue Ridge’ featured with wilted plants and defoliated leaves, but the other four cultivars (‘Bluecrop’, ‘Brigitta’, ‘Gulfcoast’, and ‘O’Neal’) present better appearances under high temperature stress. The good performances of the four heat tolerant cultivars in response to high temperature stress may benefit from the higher transpiration rates, which can dissipate much more heat through leaf transpiration than the two heat sensitive cultivars (‘Duke’ and ‘Blue Ridge’). Thus, the heat tolerant cultivars suffered less from high temperature stress can be attributed to the higher efficiency of heat dispersion, which may be explained by the changes in the distribution pattern of stomata and the total stomatal aperture area per leaf area (SAAI) through altering the stomatal density as well as the aperture size and shape of individual stoma. These findings suggested that thermal tolerant cultivars may improve their heat dispersing efficiency through regulating stomatal traits to protect harmful impacts on chloroplast structure and function, and membrane thermostability from high temperature stress as evidenced by the intact chloroplasts as well as the higher Fv / Fm and electrolyte leakage than the two heat sensitive cultivars.

A cadmium (Cd) stress test was carried out on Eisenia fetida in artificial soil. Six Cd concentration gradient solutions (0, 50, 100, 125, 250 and 500 mg/kg) were prepared. Two treatment groups, short-term stress and long-term stress, were established. The former lasted for 10 days, and the latter lasted for 30 days. The Biolog ECO-microplate culture method was used to determine the utilization of the 31 carbon sources by the microbes in earthworm homogenate. The total protein content (TP), peroxidase activity (POD), catalase activity (CAT), superoxide dismutase activity (SOD), glutathione peroxidase activity (GPX), glutathione-S-transferase activity (GST), malondialdehyde content (MDA) and acetylcholinesterase activity (AChE) in earthworm were determined in order to investigate the regulation of oxidative stress and the functional diversity of microbial communities in earthworms under Cd stress. By combining the entropy weight method (EW) and the technique for order preference by similarity to an ideal solution model (TOPSIS), the physiological functional indices of earthworms were assessed objectively and scientifically, and the physiological changes under the different stress periods were evaluated. The results showed that a Cd-tolerant dominant population appeared in the microbial community under Cd stress. In the short-term test, oxidative stress were more effective in coping with Cd stress than the microbial community, and oxidative stress regulated the microbial community functional diversity. Under long-term Cd stress, the regulatory effect was weak or non-existent. In this study, a new evaluation model was established to explore the regulation process of earthworm on its oxidation stress and the functional diversity of microbial communities under Cd stress, and provide a theoretical basis for revealing the detoxification mechanism of earthworms.

The development of efficient and environment-benign catalytic materials to activate peroxymonosulfate (PMS) for refractory pollutant removal has been considered as an attractive yet challenging topic in the field of wastewater treatment. Herein, carbon fiber-assisted iron carbide (Fe3C@CFs) was innovatively prepared by a hydrothermal and calcination method. Fe3C@CFs could activate PMS and remove the pollutant Acid Red 1 (AR1) up to 97.3%, and even the rate constant was 12.4 times higher than that of Fe3C. The leaching of iron ions was only 0.002 ppm, which was extremely lower than the European standard. Furthermore, Fe3C@CFs still exhibited a favorable catalytic performance after 4 cycles. The catalytic mechanism was investigated by a hybrid method of various radical scavengers combined with electron spin resonance, suggesting that 1O2 served as the main reaction oxidation species rather than ˙OH or SO4˙− during the catalytic process, different from most of the reported radical paths for activating PMS. In addition, Fe3C@CFs possessed wide pH adaptability (3–10) and relatively low activation energy (24.47 kJ mol−1) for AR1 removal. These findings pave a promising avenue to develop highly efficient and eco-friendly catalytic materials for environmental remediation.

Two porphyrin sensitizers, SGT-023 and SGT-025, were synthesized through acceptor structural engineering. SGT-023 was designed by replacing the commonly used benzothiadiazole (BTD) unit in the well-known platform of D-porphyrin-triple bond-BTD-acceptor sensitizers (e.g., SM315 and SGT-021) with a pyridothiadiazole unit as a stronger electron-withdrawing group. As for SGT-025, an additional ethynylene bridge was inserted into the acceptor part of the well-known skeleton of D-porphyrin-triple bond-BTD-acceptor sensitizers. The impact of the auxiliary acceptors on the optical, electrochemical, and photovoltaic properties was investigated and compared with a benchmark dye, SGT-021, developed by our group. Consequently, both porphyrin sensitizers could red-shift the absorption range and downshift the lowest unoccupied molecular orbital (LUMO) energy level, which was supposed to achieve higher light harvest efficiency (LHE). Under standard global AM 1.5G solar light conditions, SGT-025 attained a relatively high maximum power conversion efficiency (PCE) of 11.0%, which was slightly lower than that of the reference dye SGT-021 (12.6%), and a moderate PCE of 5.6% was obtained by SGT-023. The main reason is the lower charge collection efficiency, which can be attributed to the tilted dye adsorption mode on TiO2. This may allow for faster charge recombination which eventually leads to lower Jsc, Voc and PCE.

Land albedo is an essential variable in land surface energy balance and climate change. Within regional land, albedo has been altered in Greenland as ice melts and runoff increases in response to global warming against the period of the pre-industrial revolution. The assessment of spatiotemporal variation in albedo is a prerequisite for accurate prediction of ice sheet loss and future climate change, as well as crucial prior knowledge for improving current climate models. In our study, we employed the satellite data product from the global land surface satellite (GLASS) project to obtain the spatiotemporal variation of albedo from 1981 to 2017 using the non-parameter-based M-K (Mann-Kendall) method. It was found that the albedo generally showed a decreasing trend in the past 37 years (-0.013&plusmn, 0.001 decade-1, p&lt, 0.01), in particular, the albedo showed a significant increasing trend in the middle part of the study area but a decreasing trend in the coastal area. The interannual and seasonal variations of albedo showed strong spatial-temporal heterogeneity. Additionally, based on natural and anthropogenic factors, in order to further reveal the potential effects of spatiotemporal variation of albedo on the regional climate, we coupled climate model data with observed data documented by satellite and adopted a conceptual experiment for detections and attributions analysis. Our results showed that both the greenhouse gas forcing and aerosol forcing induced by anthropogenic activities in the past 37 decades were likely to be the main contributors (46.1%) to the decrease of albedo in Greenland. Here, we indicated that overall, Greenland might exhibit a local warming effect based on our study. Albedo&ndash, ice melting feedback is strongly associated with local temperature changes in Greenland. Therefore, this study provides a potential pathway to understanding climate change on a regional scale based on the coupled dataset.

Among various photovoltaic devices, dye-sensitized solar cells (DSSCs) are one of the most potentially clean and renewable energy conversion devices because of their low fabrication cost, environmentally friendly nature, and high power conversion efficiency. However, the use of rare metals such as Pt counter electrodes (CEs) is one of the major drawbacks of DSSC devices for broad real-life applications. In this regard, alternative materials to Pt CEs have been long sought for DSSCs employing both cobalt and iodine redox couples. Therefore, in this study, soft-templated tellurium-doped mesoporous carbons (Te-SMCs) were synthesized for the first time by the simple pyrolysis of PAN- b-PBA block copolymer in the presence of a tellurium precursor for replacing the Pt CE. To confirm the chemical composition and porosity, the as-prepared Te-SMC materials were evaluated by elemental analysis (XPS and EDS) and nitrogen sorption isotherms measurement. The as-prepared Te-SMC materials contained mainly mesopores and retained the three-dimensional hierarchical graphite-like structure with many defect sites. They displayed doping levels with nitrogen of 9.15 atom % and tellurium of 0.15 atom % and had a specific surface area of 540 m

One-step introduction of metallic Bi, non-metallic C into Bi2WO6 was successfully prepared via a facile hydrothermal synthetic route. The obtained materials were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope, X-ray photoelectron spectroscopy (XPS), nitrogen absorption–desorption isotherms, photoluminescence spectroscopy, photocurrent responses, electrochemical impedance spectroscopy (EIS), electron paramagnetic resonance (EPR), UV–vis diffuse reflectance spectra (DRS). As a result, C/Bi codecorated Bi2WO6 shows profoundly photocatalytic activity in comparison with undoped Bi2WO6 for decomposition of various industrial pollutants, including phenol, ciprofloxacin, bisphenol A, rhodamine B, and methyl orange under visible light (λ ≥ 420 nm). The enhanced photocatalytic properties may be ascribed to the fact that the synergistic effects of the SPR effect of Bi metal and the hybrid orbital constructed by C doping not only enhance the absorption of visible light but also accelerate the separation and migration of photo-generated carriers. Moreover, on the basis of the radical species trapping experiments, EPR analyses, DRS technique and Mott–Schottky plots, we proposed a simple photocatalytic mechanism.

The detection of terahertz electromagnetic waves is crucial for emerging applications within this frequency band, such as spectroscopy, imaging, and communication. Extending the well-developed uncooled infrared focal plane array technology to terahertz frequency regime would be very attractive, but high absorption in the terahertz region with a subwavelength pixel is necessary. In this paper, we proposed a meander line nanoantenna (MLNA) absorber with a metal-insulator-metal structure for subwavelength terahertz absorption. 89% absorption is achieved at the wavelength of 155 μm with a 10 μm pitch size. The MLNA absorber is polarization insensitive and can maintain a high absorption when the incident angle is within 40°. We expect that the proposed MLNA absorber can be integrated with the small pixels of uncooled infrared focal plane array for terahertz detection.

Understanding the key processes and mechanisms of photosynthetic and respiratory acclimation of maize (Zea mays L.) plants in response to experimental warming may further shed lights on the changes in the carbon exchange and Net Primary Production (NPP) of agricultural ecosystem in a warmer climate regime. In the current study, we examined the temperature responses and sensitivity of foliar photosynthesis and respiration for exploring the mechanisms of thermal acclimation associated with physiological and biochemical processes in the North China Plain (NCP) with a field manipulative warming experiment. We found that thermal acclimation of An as evidenced by the upward shift of An-T was determined by the maximum velocity of Rubisco carboxylation (Vcmax), the maximum rate of electron transport (Jmax), and the stomatal- regulated CO2 diffusion process (gs), while the balance between respiration and photosynthesis (Rd/Ag), and/or regeneration of RuBP and the Rubisco carboxylation (Jmax/Vcmax) barely affected the thermal acclimation of An. We also found that the temperature response and sensitivity of Rd was closely associated with the changes in foliar N concentration induced by warming. These results suggest that the leaf-level thermal acclimation of photosynthesis and respiration may mitigate or even offset the negative impacts on maize from future climate warming, which should be considered to improve the accuracy of process-based ecosystem models under future climate warming.

Temperate plants may show different photosynthetic acclimation capacities, involving varying physiological processes/mechanisms, during different seasons in response to global warming because of seasonal climate variation. Thus, we conducted field warming experiments for winter wheat in its four seasonal periods. These experiments allowed us to examine the thermal acclimation of photosynthesis and the underlying processes/mechanisms (RuBP-carboxylation, RuBP-regeneration, stomatal conductance and the balance between respiration and photosynthesis) to both seasonality and warming effects as well as the interaction between them. We found winter wheat displayed nonlinear acclimation to the seasonal temperature change, and significant acclimation to experimental warming in the four seasons. However, the acclimation capability in response to experimental warming was lower in January than November/April/May. Importantly, the underlying physiological processes/mechanisms to warming effects vary among seasonal periods: RuBP carboxylation contributed to the acclimation of photosynthesis in November and April, while the balance between respiration and photosynthesis caused the major change in January, and lower stomatal conductance played the most important role in May. These results could give insights into the decrease in productivity and increase of biomass accumulation and could help to predict acclimation capability and underlying processes to global warming. In addition, photosynthetic parameters reported here could be used to incorporate seasonal dynamics of thermal acclimation into physiological-process-based ecosystem models.

Temperature response and sensitivity of photosynthesis and respiration are critical for projection of changes in the carbon exchange and net primary production of terrestrial ecosystems under global warming. Understanding the mechanisms and processes of photosynthetic and respiratory acclimation in response to warming may shed further lights on the change of crop yield in agricultural ecosystems in a warmer climate regime. We examined the temperature responses and sensitivity of net photosynthetic rate (An) and dark respiration (Rd) for exploring the mechanisms of thermal acclimation associated with physiological and biochemical processes affecting maize yield in the North China Plain with a field manipulative warming experiment. We found that warming substantially enhanced the carbon gain of maize plants through facilitating CO2 diffusion from ambient air to chloroplasts by altering stomatal structure and spatial distribution pattern, and benefitting CO2 assimilation efficiency with smaller vascular bundles and bigger chloroplasts. Moreover, we also found that acclimation of An to temperature (T), evidenced by the upward shift of An–T, was determined by the maximum velocity of Rubisco carboxylation (Vcmax), the maximum rate of electron transport (Jmax), and the stomatal-regulated CO2 diffusion process, whereas the balance between respiration and gross photosynthetic rate (Rd/Ag), and/or regeneration of RuBP and the Rubisco carboxylation (Jmax/Vcmax) made little contribution to the thermal acclimation of An in maize plants. In addition, temperature response and sensitivity of Rd was closely associated with the changes in foliar N concentration induced by warming. As a result, experimental warming barely affected the yield and biomass of maize plants. These results suggest that the impacts of future climate warming on maize production may be mitigated or even offset by the leaf-level thermal acclimation of photosynthesis and respiration. Our findings may have important implications for improving the accuracy of process-based ecosystem models and advancing the understanding on the interactions between ecosystem functions and climate warming.

Increasing energy consumption worldwide and environmental concerns about global warming have attracted great interest in the development of renewable and eco-friendly energy technologies. Dye-sensitized solar cells (DSSCs) have attracted considerable attention over the last 25 years since they offer possible low-cost conversion of photovoltaic energy. The sensitizer is the most important component of a DSSC, as it is largely responsible for light harvesting and charge separation, as well as the dye regeneration process. As a result, there have been tremendous research efforts in developing sensitizers. However, many challenges remain, and a deeper understanding of the design rules of DSSC sensitizers is required to obtain efficient and long-term stable DSSCs. The purpose of this review is to discuss recent progress and the rational design criteria used in the structural design of organic dyes and porphyrin photosensitizers for use in DSSCs. The effects of molecular structural engineering on the photophysical and electrochemical properties, photovoltaic parameters, and efficiency of DSSCs are presented.

The South China Sea (SCS) is an important channel, which plays a significant role in global economic trade and in the maintenance of world energy security. A series of artificial lands have been successfully built on the top of natural coral reefs in the SCS by the way of reclamation in recent years. In order to prevent those artificial lands from wave scouring and impacting, a great number of revetments and breakwaters have been constructed along the margin of these artificial lands. The revetment breakwaters have great significance and practical value to ensure the stability of these reclaimed lands, and to guarantee their normal long-term service performance. In this study, taking the reclamation project in the SCS as the engineering background, a computation model for the interaction between ocean waves, revetment breakwater and its calcareous coral sand foundation is established by taking the CFD solver OlaFlow as the computation platform which was developed based on the open source library OpenFOAM. Then this established computation model is verified by some laboratory testing data of wave profile and wave impact which have been measured in several wave flume physical model tests. The comparison between the testing data and the computational results indicates that the computation model established adopting OlaFlow can reliably simulate the wave generation, propagation, the dissipation of wave energy as well as the complicated interaction between ocean wave, the revetment breakwater and its calcareous coral sand foundation. This verification work will be a solid basis for the subsequent investigation of the interaction between severe ocean waves and the revetment breakwaters in large-scale, as well as the quantitative evaluation of the stability of the revetment breakwater build on reclaimed coral sand foundation in the SCS.

Zn(II)-porphyrin dyes (SGT-030 and SGT-031) with extended auxiliary π-spacers in the donor (D) part have been prepared and applied to dye-sensitized solar cells (DSSCs). The porphyrin dyes containe...

Soil cadmium (Cd) pollution has received increasing attention from scholars. In the field of Cd pollution remediation, there is an urgent need to study the combined bioremediation technology of earthworms and microbes. In this paper, a short-term stress test and a long-term stress test were conducted. Eisenia fetida were inoculated into artificial soil that was contaminated with Cd. After different Cd stress times, the regulation process between the microbial communities in the earthworms and in the soil was studied. Canonical correlation analysis and the TOPSIS method were combined to establish a mathematical model for data analysis, and the changes in the carbon source utilization intensity by microbes were analysed. The results showed that in the short-term stress tests, the regulation process could be divided into five stages. Specifically, after 1–3 days of stress, the microbial community in the earthworms regulated the soil microbial community, but on the 3rd day, the regulation was weakened. On the 4th day, the soil microbial community was affected not only by the microbes in the earthworms but also by the increasing intensity of Cd stress. After 5 days of stress, the microbial communities in the earthworms and the soil were both greatly affected by Cd poisoning, and the microbes transitioned from stable to declining. At 6–7 days, the microbes in the earthworms gained control over those in the soil once again, and the Cd-tolerant microbes began to appear and proliferate. At 8–10 days, the regulation of the soil microbes by the earthworm microbes weakened, while the Cd-tolerant population in the soil microbial communities gradually evolved at this stage to adapt to the increasing Cd stress. The long-term stress tests showed that the difference between the microbial communities in the soil and in the earthworms increased, and there was almost no regulation between them.

Two porphyrin-based sensitizers, SGT-028 and SGT-029, were designed and synthesized via acceptor engineering for application in dye-sensitized solar cells (DSSCs). Porphyrin SGT-028 was designed by introducing a salicylic acid anchoring group instead of a conventional benzoic acid in the platform of donor-porphyrin-triple bond-BTD-phenyl-acceptor sensitizers (e.g., SGT-021 and SM315). As for SGT-029, an additional alkylated benzothiadiazole (BTD) unit was substituted to the BTD of D-π-A porphyrin sensitizers. The impact of the anchoring group and long alkyl chains on the optical character, electrochemical property, and photovoltaic performance were studied and also compared with a reference dye of SGT-021, which had previously been synthesized by our group. As a result, both of these two porphyrin sensitizers obtained a similar absorption range and energy band gap to SGT-021 dye. After performing optimization of DSSC devices, SGT-029 achieved a comparatively high power conversion efficiency (PCE) of 10.5%, but was inferior to the benchmark porphyrin sensitizer SGT-021 (12.7%), and a slightly lower PCE of 9.1% was exhibited by SGT-028, under the standard AM 1.5G light intensity. It is worth mentioning that the PCE of 12.7% is the highest efficiency for a SGT-021-based device up to now. The main reason was supposed to be the dye adsorption amount difference, maybe allowing for a serious dye aggregation, which often leads to an increased quenching of excited states and limits the charge injection into the TiO2 semiconductor substrate, and lower light harvest efficiency (LHE), resulting in lower photocurrent, photovoltage, and PCE.

A series of tetra-functional fluorene-based benzoxazines containing both flexible linear aliphatic chain and rigid aromatic structure in their backbones were synthesized using mixed amines such as aniline and n-octylamine, 2,7-dihydroxy-9,9-bis-(4-hydroxyphenyl)fluorene (THPF) and paraformaldehyde as raw materials via Mannich reaction. The prepared benzoxazine monomers were identified by fourier transform infrared spectroscopy (FTIR), hydrogen nuclear magnetic resonance (1H NMR). In addition, the curing behavior, curing kinetics and rheological properties of these monomers as well as the thermal and mechanical properties of their cured resins were studied using a rheometer, differential scanning calorimeter (DSC), thermogravimetric analyzer (TGA), and dynamic thermomechanical analyzer (DMA). The newly developed benzoxazines show good processibility, excellent thermal stability and high glass transition temperature (Tg) values ranging from 291 to 307 °C. By varying the proportion of n-octylamine to aniline, the properties of these resins are tuned.

Background Thyroid cancer incidence has increased substantially over the past decades, and environmental risk factors have been suggested to play a role. Polychlorinated biphenyls (PCB) and organochlorine pesticides (OCP) are established thyroid hormone disruptors, but their relationship to thyroid cancer is not known. Methods We investigated the relationship between serum PCB and OCP concentrations and papillary thyroid cancer (PTC) in 250 incident female PTC cases and 250 female controls frequency-matched on age, all residing in Connecticut. Interviews and serum samples were collected from 2010 to 2013. Samples were analyzed for 32 different chemicals using gas chromatography with isotope dilution high resolution mass spectrometry. We calculated odds ratios (OR) and 95% confidence intervals (CI) using single pollutant logistic regression models for concentrations (per interquartile range) of individual PCB/OCP and summed groups of structurally or biologically similar PCB/OCP, adjusted for education, family history of cancer, alcohol consumption, age, and body mass index. Sub-analyses included stratification by tumor size (≤ and >1 cm) and birth before or during peak PCB production (born in 1960 or earlier and born after 1960), as exposures during early life may be important. We also applied three multi-pollutant approaches (standard multi-pollutant regression, hierarchical Bayesian modeling, principal components regression analysis) to investigate associations with co-exposures to multiple PCB/OCPs. Results No PCB/OCPs were positively associated with PTC in primary analyses. Statistically significant associations were observed for 9 of the 32 chemicals and 3 summed groups of similar chemicals in the those born during peak production based on single-pollutant models. Multi-pollutant analyses suggested null associations overall. Conclusions Our results using single and multi-pollutant modeling do not generally support an association between PCB or OCP exposure and PTC, but some associations in those born during peak production suggest that additional investigation into early-life exposures and subsequent thyroid cancer risk may be warranted.

Understanding the processes and mechanisms of crops in response to elevated CO2 concentration and water stress is critical for accurately projecting the potential risk of climate change on global agriculture productivity. We examined effects of elevated CO2 concentration on plant growth, stomatal traits, leaf gas exchange, and biochemistry of bell peppers under water stresses with environmental growth chambers controlling CO2 concentration at ambient (400 μmol mol−1) or elevated (800 μmol mol−1) CO2 level along a soil water gradient including full irrigation (75–85 % FC), mild water stress (65–75 % FC), moderate water stress (55–65 % FC), and severe water stress (45–55 % FC). We found that rising atmospheric CO2 concentration dramatically enhanced the plant biomass of bell peppers through the strong CO2 fertilization effect even under the mild and moderate water stresses. The CO2 fertilization effect on plant growth under water stress was directly confirmed by the boosted leaf photosynthesis, which can be attributed to the increased stomatal number and the larger stomatal openness as well as the more regular spatial distribution patterns of bell pepper plants grown at high CO2 concentration and water stress. As a result, the leaf-level water use efficiency was enhanced due to the stimulated leaf photosynthesis and the reduced leaf transpiration under high CO2 concentration, even for these bell pepper plants are suffering water stresses. Nevertheless, this CO2 fertilization effect on plant growth and leaf photosynthesis were generally decreased along the soil water gradients, indicating that the CO2 fertilization effect may partially be mitigated or even offset by water availability as evidenced by the little impact of high CO2 concentration on the total biomass of pepper plants under severe water stress. Our results suggest that water stress may lower the CO2 fertilization effect on plant growth of bell pepper plants, thus current ecological processes models based on the strong CO2 fertilization effect may overestimate the benefits of plants from future rising CO2 concentration, and meanwhile underestimate the potential risk of climate change on global agricultural productivity, where elevated CO2 concentration is usually accompanied by regional drought events.

The rational design of porphyrin sensitizers is always crucial for dye-sensitized solar cells (DSSCs), since the change of only a single atom can have a significant influence on the photovoltaic performance. We incorporated the pyridothiadiazole group, as a stronger electron-withdrawing group, into the commonly well-established skeleton of D-porphyrin-triple bond-acceptor sensitizers by a single atom change for a well-known strong electron-withdrawing benzothiadiazole (BTD) unit as an auxiliary acceptor. The impact of the pyridothiadiazole group on the optical, electrochemical, and photovoltaic properties of D&ndash, &pi, &ndash, A porphyrin sensitizers was investigated with comparison for a benzothiadiazole-substituted SGT-020 porphyrin. The pyridothiadiazole-substituted SGT-024 porphyrin dye was red-shifted so that the absorption range might be expected to achieve higher light harvest efficiency (LHE) than the SGT-020 porphyrin. However, all the devices were fabricated by utilizing SGT-020 and SGT-024, evaluated and found to achieve a cell efficiency of 10.3% for SGT-020-based DSSC but 4.2% for SGT-024-based DSSC under standard global AM 1.5G solar light conditions. The main reason is the lower charge collection efficiency of SGT-024-based DSSC than SGT-020-based DSSC, which can be attributed to the tilted dye adsorption mode on the TiO2 photoanode. This may allow for faster charge recombination, which eventually leads to lower Jsc, Voc and power conversion efficiency (PCE).

CO(2), temperature, water availability, and light intensity were all potential selective pressures that determined the competitive advantage and expansion of the C(4) photosynthetic carbon-concentrating mechanism over the last ∼30 My. To tease apart how selective pressures varied along the ecological trajectory of C(4) expansion and dominance, we coupled hydraulics to photosynthesis models while optimizing photosynthesis over stomatal resistance and leaf/fine-root allocation. We further examined the importance of nitrogen reallocation from the dark to the light reactions. We show here that the primary selective pressures favoring C(4) dominance changed through the course of C(4) evolution. The higher stomatal resistance and leaf-to-root ratios enabled by C(4) led to an advantage without any initial difference in hydraulic properties. We further predict a reorganization of the hydraulic system leading to higher turgor-loss points and possibly lower hydraulic conductance. Selection on nitrogen reallocation varied with CO(2) concentration. Through paleoclimate model simulations, we find that water limitation was the primary driver for a C(4) advantage, with atmospheric CO(2) as high as 600 ppm, thus confirming molecular-based estimates for C(4) evolution in the Oligocene. Under these high-CO(2) conditions, nitrogen reallocation was necessary. Low CO(2) and high light, but not nitrogen reallocation, were the primary drivers for the mid- to late-Miocene global expansion of C(4). We also predicted the timing and spatial distribution for origins of C(4) ecological dominance. The predicted origins are broadly consistent with prior estimates, but expand upon them to include a center of origin in northwest Africa and a Miocene-long origin in Australia.

Cadmium (Cd) contamination in soil has become the focus of widespread concern in society today. In this paper, with Eisenia fetida as research subjects, an indoor simulation experiment was conducted. A BIOLOG microplate technique was used to determine the carbon source (single-carbon) utilization of the microbial communities in the contaminated soil and earthworms under Cd stress. Contour line analysis was used for the first time to study the difference of carbon source metabolism in microbial communities. And the effects of Cd stress on the functional diversity of the microbial communities and the detoxification mechanism in earthworms were researched. With two test groups, a short-term test and the long-term test were performed. The former test lasted for 10 days, with the removal of an earthworm every day for analysis; the latter test lasted for 30 days, with the removal of an earthworm every 10 days. The Cd2+ concentration was set at 0, 50, 100, 125, 250, or 500 mg kg−1 dry weight, and 10 earthworms were inoculated in each concentration treatment. The earthworm homogenate and soil extracts were used to determine the carbon source utilization of the microbial communities. The results show that Cd stress changed the functional diversity of the microbial communities in the soil and earthworms. With the extension of stress time and the increase of stress concentration, earthworms will adjust their own physiological functions (including the microbial community structure and stress mechanism in the body) and regulate the microbial community structure in the external environment to obtain the necessary substances for growth. In addition, 2-hydroxybenzoic acid, γ-hydroxybutyric acid, glutamyl-L-glutamic acid, α-butyric acid, threonine, and α-cyclodextrin were important carbon sources for the earthworms to maintain their normal physiological metabolism under Cd stress. This study confirms that changes in microbial communities can be used to reveal the detoxification mechanisms of earthworm under heavy metal stress.

Artificial soil simulation tests were conducted to study the response of oxidative stress in different parts of Eisenia fetida under cadmium Cd) stress. Factor analysis and analytic hierarchy process were used to establish a comprehensive mathematical model to screen key monitoring indices of the Cd-contaminated soil early warning system. This paper sets the short-term group and the long-term group. The former lasted 10 days, and the latter was 30 days. Gradient solution of 0, 50, 100, 125, 250, and 500 mg kg−1 Cd2+ was used in each test group. The earthworm was cut into two parts from its clitellum to determine oxidative stress indices. Results showed that during the short-term stress, TP (total protein) in the head tissues of the earthworm was the key monitoring index for 3–4 and 8–9 days of Cd stress. In addition, the TP in tail tissues was the key index for 2, 4, 6, and 8–10 days of stress. On the first and second days, the key monitoring indices in the tail tissues were both the CAT (catalase), while in the head, they were CAT and TP, respectively. On the 5th, the 7th, and the 9th days, the focus should be on monitoring POD (peroxidase) in the tail tissues, while in the head tissues, they were POD, CAT, and TP, respectively. In the long-term test after 10 days of Cd stress, the key monitoring index in head tissues was GPX (glutathione peroxidase), and in the tail, it was TP. At 20–30 days, the key monitoring indices were TP in the head and MDA (malondialdehyde) in the tail.

In this study, the TiO2/Bi4V2O[Formula: see text] nanocomposite photocatalysts were prepared by loading different amount of TiO2 nanoparticles onto the surface of Bi4V2O[Formula: see text] nanospheres via a facile hydrothermal method. Afterwards, the as-synthesized samples were characterized by high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), N2 adsorption–desorption isotherms, X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectroscopy (DRS) and photocurrent techniques. The optimal TiO2/Bi4V2O[Formula: see text] composite with 20[Formula: see text]wt.% TiO2 loading (TB2) exhibited the best photocatalytic activity, which could degrade almost RhB completely within 30[Formula: see text]min under visible light irradiation. The enhanced photocatalytic activity of TiO2/Bi4V2O[Formula: see text] composites for RhB degradation could be mainly ascribed to the efficient charge separation over dye-induced sensitized and the increased specific surface area. Also, the photocatalytic activities of TiO2/Bi4V2O[Formula: see text] for CIP degradation were tested. After five consecutive recycling experiments, the photocatalytic degradation activity of TB2 could still reach 99% which indicated that the catalysts had superior stability. Based on the experimental and bandgap calculations, a possible photocatalytic mechanism of TiO2/Bi4V2O[Formula: see text] for RhB degradation was proposed.