Protein disulfide isomerase 1 is required for RodA assembling-based conidial hydrophobicity of Aspergillus fumigatus.

The hydrophobic layer of Aspergillus conidia, composed of RodA, plays a crucial role in conidia transfer and immune evasion. It self-assembles into hydrophobic rodlets through intramolecular disulfide bonds. However, the secretory process of RodA and its regulatory elements remain unknown. Since protein disulfide isomerase (PDI) is essential for the secretion of many disulfide-bonded proteins, we investigated whether PDI is also involved in RodA secretion and assembly. By gene knockout and phenotypic analysis, we found that Pdi1, one of the four PDI-related proteins of Aspergillus fumigatus, determines the hydrophobicity and integrity of the rodlet layer of the conidia. Preservation of the thioredoxin-active domain of Pdi1 was sufficient to maintain conidial hydrophobicity, suggesting that Pdi1 mediates RodA assembly through its disulfide isomerase activity. In the absence of Pdi1, the disulfide mismatch of RodA in conidia may prevent its delivery from the inner to the outer layer of the cell wall for rodlet assembly. This was demonstrated using a strain expressing a key cysteine-mutated RodA. The dormant conidia of the Pdi1-deficient strain (Δpdi) elicited an immune response, suggesting that the defective conidia surface in the absence of Pdi1 exposes internal immunogenic sources. In conclusion, Pdi1 ensures the correct folding of RodA in the inner layer of conidia, facilitating its secretion into the outer layer of the cell wall and allowing self-assembly of the hydrophobic layer. This study has identified a regulatory element for conidia rodlet assembly.IMPORTANCEAspergillus fumigatus is the major cause of invasive aspergillosis, which is mainly transmitted by the inhalation of conidia. The spread of conidia is largely dependent on their hydrophobicity, which is primarily attributed to the self-assembly of the hydrophobic protein RodA on the cell wall. However, the mechanisms underlying RodA secretion and transport to the outermost layer of the cell wall are still unclear. Our study identified a critical role for Pdi1, a fungal protein disulfide isomerase found in regulating RodA secretion and assembly. Inhibition of Pdi1 prevents the formation of correct S-S bonds in the inner RodA, creating a barrier to RodA delivery and resulting in a defective hydrophobic layer. Our findings provided insight into the formation of the conidial hydrophobic layer and suggested potential drug targets to inhibit A. fumigatus infections by limiting conidial dispersal and altering their immune inertia.

Nitrogen mitigates the negative effects of combined heat and drought stress on winter wheat by improving physiological characteristics.

Extreme drought stress is often accompanied by heat stress after anthesis in winter wheat. Whether nitrogen (N) can mitigate the damage caused by combined stress on wheat plants by regulating root physiological characteristics is still unclear. Thus, this study aimed to study the effects of combined heat and drought stress on photosynthesis, leaf water relations, root antioxidant system, osmoregulatory, and yield in wheat to reveal the physiological mechanism of N regulating the adverse impacts of combined stress on wheat. Heat and drought stress markedly reduced photosynthesis, leaf water content, root vitality, and bleeding sap. The combination of heat and drought strengthens these changes. Within a certain stress range, the increase in soluble sugar and proline contents and the activities of superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase under combined stress effectively alleviated the oxidative damage. Compared with those under high N application (N3), wheat plants under low N application (N1) maintained higher yield and yield components under combined stress; the number of grains per spike, 1000-grain weight, and yield increased by 13.65%, 9.07%, and 15.33%, respectively, under N1 compared with those under N3 treatment, which may be attributed to the greater maintenance of photosynthesis, leaf water status, root vitality, and antioxidant and osmoregulation capacities. In summary, reduced N application mitigated the damage caused by combined heat and drought stress in wheat by improving root physiological characteristics and enhanced adaptability to combined stress, which is an appropriate strategy to compensate for yield losses.

Monitoring soil moisture in winter wheat with crop water stress index based on canopy-air temperature time lag effect.

Crop water stress index (CWSI) has been widely used in soil moisture monitoring. However, the influence of the time lag effect between canopy temperature and air temperature on the accuracy of soil moisture monitoring with different CWSI models has not been further investigated. Therefore, based on the continuous record of canopy temperature and air temperature, this study explored the influence of canopy-air temperature hysteresis on the diagnosis of soil moisture with three CWSI models (CWSIT-theoretical, CWSIE-empirical, CWSIH-hybrid). The results show (1) the peak time of canopy temperature was ahead of that of air temperature, and the lag time varied under different soil moisture conditions. When the soil moisture was seriously deficient, the lag time decreased. However, from jointing-heading period to filling-ripening period, the lag time became longer. (2) The values of CWSIT, CWSIE, and CWSIH decreased when the time lag effect was considered. In jointing-heading period, heading-filling period, and filling-ripening period, CWSIT had the highest accuracy in soil moisture monitoring without the consideration of the time lag effect. When the time lag effect was considered, the monitoring accuracy of CWSIE and CWSIH was greatly improved and higher than that of CWSIT, while that of CWSIT was reduced. The findings provided a basis for further improving the accuracy of soil moisture monitoring with CWSI models.

Cytosol Peroxiredoxin and Cell Surface Catalase Differentially Respond to H2O2 Stress in Aspergillus nidulans.

Both catalase and peroxiredoxin show high activities of H2O2 decomposition and coexist in the same organism; however, their division of labor in defense against H2O2 is unclear. We focused on the major peroxiredoxin (PrxA) and catalase (CatB) in Aspergillus nidulans at different growth stages to discriminate their antioxidant roles. The dormant conidia lacking PrxA showed sensitivity to high concentrations of H2O2 (>100 mM), revealing that PrxA is one of the important antioxidants in dormant conidia. Once the conidia began to swell and germinate, or further develop to young hyphae (9 h to old age), PrxA-deficient cells (ΔprxA) did not survive on plates containing H2O2 concentrations higher than 1 mM, indicating that PrxA is an indispensable antioxidant in the early growth stage. During these early growth stages, absence of CatB did not affect fungal resistance to either high (>1 mM) or low (<1 mM) concentrations of H2O2. In the mature hyphae stage (24 h to old age), however, CatB fulfills the major antioxidant function, especially against high doses of H2O2. PrxA is constitutively expressed throughout the lifespan, whereas CatB levels are low in the early growth stage of the cells developing from swelling conidia to early growth hyphae, providing a molecular basis for their different contributions to H2O2 resistance in different growth stages. Further enzyme activity and cellular localization analysis indicated that CatB needs to be secreted to be functionalized, and this process is confined to the growth stage of mature hyphae. Our results revealed differences in effectiveness and timelines of two primary anti-H2O2 enzymes in fungus.

Semi-Cycled Generative Adversarial Networks for Real-World Face Super-Resolution.

Real-world face super-resolution (SR) is a highly ill-posed image restoration task. The fully-cycled Cycle-GAN architecture is widely employed to achieve promising performance on face SR, but is prone to produce artifacts upon challenging cases in real-world scenarios, since joint participation in the same degradation branch will impact final performance due to huge domain gap between real-world and synthetic LR ones obtained by generators. To better exploit the powerful generative capability of GAN for real-world face SR, in this paper, we establish two independent degradation branches in the forward and backward cycle-consistent reconstruction processes, respectively, while the two processes share the same restoration branch. Our Semi-Cycled Generative Adversarial Networks (SCGAN) is able to alleviate the adverse effects of the domain gap between the real-world LR face images and the synthetic LR ones, and to achieve accurate and robust face SR performance by the shared restoration branch regularized by both the forward and backward cycle-consistent learning processes. Experiments on two synthetic and two real-world datasets demonstrate that, our SCGAN outperforms the state-of-the-art methods on recovering the face structures/details and quantitative metrics for real-world face SR. The code will be publicly released at https://github.com/HaoHou-98/SCGAN.

The Roles of Riblet and Superhydrophobic Surfaces in Energy Saving Using a Spatial Correlation Analysis.

Riblet and superhydrophobic surfaces are two typical passive control technologies used to save energy. In this study, three microstructured samples-a micro-riblet surface (RS), a superhydrophobic surface (SHS), and a novel composite surface of micro-riblets with superhydrophobicity (RSHS)-were designed to improve the drag reduction rate of water flows. Aspects of the flow fields of microstructured samples, including the average velocity, turbulence intensity, and coherent structures of water flows, were investigated via particle image velocimetry (PIV) technology. A two-point spatial correlation analysis was used to explore the influence of the microstructured surfaces on coherent structures of water flows. Our results showed that the velocity on microstructured surface samples was higher than that on the smooth surface (SS) samples, and the turbulence intensity of water on the microstructured surface samples decreased compared with that on the SS samples. The coherent structures of the water flow on microstructured samples were restricted by length and structural angles. The drag reduction rates of the SHS, RS, and RSHS samples were -8.37 %, -9.67 %, and -17.39 %, respectively. The novel established RSHS demonstrated a superior drag reduction effect and could improve the drag reduction rate of water flows.

Drag Reduction Technology of Water Flow on Microstructured Surfaces: A Novel Perspective from Vortex Distributions and Densities.

Revealing the turbulent drag reduction mechanism of water flow on microstructured surfaces is beneficial to controlling and using this technology to reduce turbulence losses and save energy during water transportation. Two microstructured samples, including a superhydrophobic and a riblet surface, were fabricated near which the water flow velocity, and the Reynolds shear stress and vortex distribution were investigated using a particle image velocimetry. The dimensionless velocity was introduced to simplify the Ω vortex method. The definition of vortex density in water flow was proposed to quantify the distribution of different strength vortices. Results showed that the velocity of the superhydrophobic surface (SHS) was higher compared with the riblet surface (RS), while the Reynolds shear stress was small. The vortices on microstructured surfaces were weakened within 0.2 times that of water depth when identified by the improved ΩM method. Meanwhile, the vortex density of weak vortices on microstructured surfaces increased, while the vortex density of strong vortices decreased, proving that the reduction mechanism of turbulence resistance on microstructured surfaces was to suppress the development of vortices. When the Reynolds number ranged from 85,900 to 137,440, the drag reduction impact of the superhydrophobic surface was the best, and the drag reduction rate was 9.48%. The reduction mechanism of turbulence resistance on microstructured surfaces was revealed from a novel perspective of vortex distributions and densities. Research on the structure of water flow near the microstructured surface can promote the drag reduction application in the water field.

Individual and combined effects of heat and drought and subsequent recovery on winter wheat (Triticum aestivum L.) photosynthesis, nitrogen metabolism, cell osmoregulation, and yield formation.

Extreme temperatures and droughts are considered as the two main factors that limit wheat growth and production. Although responses of wheat plants to heat and drought stress have been extensively investigated, little is known about the extent to which wheat plants can recover after stress relief. In this study, a winter wheat pot experiment was conducted to evaluate the growth, physiological activities, and yield formation responses of wheat to stress and recovery periods under heat stress (36 °C, daily maximum temperature), drought (45-55% of soil water holding capacity), and combined stress conditions. Heat and drought stress significantly reduced photosynthesis, leaf relative water content (LRWC), leaf water potential (LWPnoon), and nitrogen metabolism enzyme activities and increased electrolyte leakage. These parameters showed significant interactions between heat and drought stress. Beneficial osmoregulation of membrane stability was observed in stressed plants because of the accumulation of proline and soluble sugars. Within a range of stresses, the abovementioned physiological processes of individual heat- and drought-stressed plants recovered to levels comparable to those of the control. The recovery capacities of the physiological traits decreased gradually with increasing stress duration, particularly under combined stress. The recovery of LWPnoon and LRWC contributed to the improved photosynthetic performance after stress relief. The combined stress caused greater yield losses than individual heat and drought stress, which was mainly attributed to low levels of thousand grain weight (TGW), the number of grains per ear, and the grain filling rate. After stress relief, the recovery of proline content, glutamine synthetase activity, photosynthetic rate, and LRWC were closely associated with grain yield and thousand grain weight. Collectively, these findings contribute to a better understanding of the coordinated responses of winter wheat during the combined heat and drought stress and recovery periods.

Photosynthetic, antioxidant activities, and osmoregulatory responses in winter wheat differ during the stress and recovery periods under heat, drought, and combined stress.

There will be longer and more intense periods of heat and drought stress in the future for terrestrial ecosystems. Although the responses of wheat plants to heat and drought stress alone have been extensively investigated, little is known about the extent to which their recovery can be assured after stress relief. In this study, a winter wheat pot experiment was conducted to investigate the changes in photosynthetic performance, antioxidant activity, osmoregulation, and membrane lipid peroxidation under heat stress (36 °C), drought (45-55% of soil water holding capacity), and combined stress conditions. The results showed that heat and drought stress significantly reduced the photosynthetic rate and the contents of chlorophyll and carotenoid. Superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and glutathione reductase (GR) activities were greatly activated by heat and drought stress to scavenge overproduced superoxide anion (O2-). Plants exhibited positive osmoregulation through the synthesis of soluble protein (SP), soluble sugar (SS), and proline (Pro) to improve membrane stability. Within a range of stress, combined heat and drought stress exhibited significant interactive effects in the above mentioned indicators. After stress relief, the majority of physiological processes were reversible, as indicated by the effective recovery of pigment contents, photosynthetic rate, antioxidant enzyme activities, osmoregulatory substance contents, and O2- production. Antioxidant enzyme activities tended to increase after recovering from 12 days of combined stress, whereas they were still not effective in mitigating oxidative damage. High levels of O2- and malondialdehyde (MDA) and a low relative growth rate during the recovery confirmed the irreversible damage caused by combined heat and drought stress. ROC (receiver operating characteristic) analysis indicated that GR and SS could accurately detect individual heat and drought stress that wheat plants were suffering or had suffered (AUC = 0.812-0.965), while POD and Pro had greater potential for diagnosing combined heat and drought stress (AUC = 0.871-0.958). Physiological indicators of stress tolerance were closely related to the photosynthetic rate during the stress, particularly Pro and GR. Collectively, the physiological processes of plants are reversible within a certain range of stress. POD, GR, Pro, and SS play vital roles in identifying and resisting heat, drought, and combined stress, and the recovery of these indicators contributed to improving photosynthesis and thereby increasing wheat growth. Our research contributes to the understanding of the underlying physiological mechanisms of plants in response to combined heat and drought stress and after stress relief.

Realizing Single Chip White Light InGaN LED via Dual-Wavelength Multiple Quantum Wells.

Dual-wavelength multiple quantum wells (MQWs) have great potential in realizing high quality illumination, monolithic micro light-emitting diode (LED) displays and other related fields. Here, we demonstrate a single chip white light indium gallium nitride (InGaN) LED via the manipulation of the dual-wavelength MQWs. The MQWs contain four pairs of blue light-emitting MQWs and one pair of green light-emitting QW. The fabricated LED chips with nickel/gold (Ni/Au) as the current spreading layer emit white light with the injection current changing from 0.5 mA to 80 mA. The chromaticity coordinates of (0.3152, 0.329) closing to the white light location in the Commission International de I'Eclairage (CIE) 1931 chromaticity diagram are obtained under a 1 mA current injection with a color rendering index (CRI) Ra of 60 and correlated color temperature (CCT) of 6246 K. This strategy provides a promising route to realize high quality white light in a single chip, which will significantly simplify the production process of incumbent white light LEDs and promote the progress of high-quality illumination.

N-polar GaN Film Epitaxy on Sapphire Substrate without Intentional Nitridation.

High-temperature nitridation is commonly thought of as a necessary process to obtain N-polar GaN films on a sapphire substrate. In this work, high-quality N-polar GaN films were grown on a vicinal sapphire substrate with a 100 nm high-temperature (HT) AlN buffer layer (high V/III ratio) and without an intentional nitriding process. The smallest X-ray full width at half maximum (FWHM) values of the (002)/(102) plane were 237/337 arcsec. On the contrary, N-polar GaN film with an intentional nitriding process had a lower crystal quality. In addition, we investigated the effect of different substrate treatments 1 min before the high-temperature AlN layer's growth on the quality of the N-polar GaN films grown on different vicinal sapphire substrates.

Two-Step Deposition of an Ultrathin GaN Film on a Monolayer MoS2 Template.

Ultrathin gallium nitride (GaN) application can be profoundly influenced by its quality, especially the issue of amorphous interfacial layers formed on conventional substrates. Herein, we report a two-step deposition of an ultrathin GaN film via the plasma-enhanced atomic layer deposition (PEALD) technique on a mono-MoS2 template over a SiO2/Si substrate for quality improvement, by starting the deposition temperature at 260 °C and then ramping it to 320 °C. It was found that a lower initiating deposition temperature could be conducive to maintaining the mono-MoS2 template to support the subsequent growth of GaN. Compared to the control group of one-step high-temperature deposition at 320 °C, ideal layer-by-layer film growth is achieved at the low temperature of the two-step method instead of island formation, leading to the direct crystallization of GaN on the substrate with a rather sharp interface. Structural and chemical characterizations show that this two-step method produces a preferred [0001] orientation of the film originating from the interface region. Additionally, the improved two-step ultrathin GaN displays a smooth surface roughness as low as 0.58 nm, a low oxygen impurity concentration of 3.6%, and a nearly balanced Ga/N stoichiometry of 0.95:1. Our work paves a possible way to the feasible fabrication of ultrathin high-quality PEALD-GaN, and it is promising for better performance of relevant devices.

Effects of clouds and aerosols on ecosystem exchange, water and light use efficiency in a humid region orchard.

Investigating the patterns of water and carbon dynamics in agro-ecosystems in response to clouds and aerosols can shed new insights in understanding the biophysical impacts of climate change on crop productivity and water consumption. In this study, the effects of clouds and aerosols as well as other environmental factors on ecosystem water and carbon fluxes were examined based on three-year eddy covariance measurements under different sky conditions (quantified as the clearness index, Kt, i.e., the ratio of global solar radiation to extraterrestrial solar radiation) in a kiwifruit plantation in the humid Sichuan Basin of China. Results showed that evapotranspiration (ET) and canopy transpiration (Tc, measured by sap flow sensors) increased, while ecosystem light use efficiency (eLUE) and ecosystem water use efficiency (eWUE) decreased with increasing Kt. GPP presented a parabolic relationship with increasing Kt. The path analysis revealed that surface conductance (Gs) and canopy conductance (Gc) were the most dominant variables directly regulated carbon (GPP) and water (ET and Tc) fluxes. The effect path of Kt on ET and Tc was converted from through diffuse photosynthetic active radiation (PARdif) to direct PAR (PARdir) when the sky became clearer. The effect path of Kt on GPP was primarily through PARdif under different sky conditions. The declined eWUE with increasing Kt was caused by the different responses of GPP and ET to PARdir under clear skies. The declined eLUE resulted from the sharp decrease in GPP/PARdir, which surpassed the slight increase of GPP/PARdif with increasing PAR. The Priestley-Taylor Jet Propulsion Laboratory ET model (PT-JPL) incorporating Kt with an exponential function produced more reliable Tc estimates but minor improvement in ET. Further, the LUE-GPP model incorporating Kt with a linear function obtained much better GPP estimates. Our study shed light on how sky conditions modulate water and carbon dynamics between the biosphere and atmosphere, highlighting the necessity of the inclusion of sky conditions for better modeling regional water and carbon budgets.

A novel intelligent fault identification method based on random forests for HVDC transmission lines.

In order to remedy the current problem of having been buffeted by competing requirements for both protection sensitivity and quick reaction of High Voltage Direct Current (HVDC) transmission lines simultaneously, a new intelligent fault identification method based on Random Forests (RF) for HVDC transmission lines is proposed. S transform is implemented to extract fault current traveling wave of 8 frequencies and calculate the fluctuation index and energy sum ratio, in which the wave index is used to identify internal and external faults, and energy sum ratio is used to identify the positive and negative pole faults occurred on the transmission line. The intelligent fault identification model of RF is established, and the fault characteristic sample set of HVDC transmission lines is constructed by using multi-scale S transform fluctuation index and multi-scale S-transform energy sum ratio. Training and testing have been carried out to identify HVDC transmission line faults. According to theoretical researches and a large number of results of simulation experiments, the proposed intelligent fault identification method based on RF for HVDC transmission lines can effectively solve the problem of protection failure caused by inaccurate identification of traditional traveling wave wavefront or wavefront data loss. It can accurately and quickly realize the identification of internal and external faults and the selection of fault poles under different fault distances and transitional resistances, and has a strong ability to withstand transitional resistance and a strong ability to resist interference.

Projections of drought characteristics in China based on a standardized precipitation and evapotranspiration index and multiple GCMs.

Droughts have destructive impacts on agricultural production; thus, drought projections are vital for the development of future drought mitigation strategies. This work aimed to project a standardized precipitation and evapotranspiration index (SPEI) at 3-, 6- and 12-month timescales for the period 2011-2100 under two representative concentration pathway (RCP) scenarios - RCP 4.5 and RCP 8.5 in mainland China and to assess the changes in various drought indices over a baseline period of 1961-2000. The spatiotemporal variations in drought characteristics (e.g., the drought occurrence time, duration, severity, peak, and frequency and the percentage of stations suffering from drought (PSSD) were estimated by the projected SPEI for the periods 2011-2040, 2041-2070 and 2071-2100. The results showed that mainland China would experience more frequent and severe droughts in the future than in the baseline period, as denoted by SPEI and the generated drought variables. In particular, drier areas of northwestern China were likely to suffer from worse drought conditions than those in other areas, with PSSD values of 60% and 81% by 2100 under the RCP4.5 and RCP 8.5 scenarios, respectively. Although the annual precipitation was projected to increase in most regions, drought conditions would still worsen because of increased the minimum and maximum air temperatures. However, the GCMs contributed more uncertainties to the projection of the SPEI than the stations or the RCPs, because the GCMs made a larger contribution to the variance (>40%). The SPEI performed better than the other indices that only accounted for the influence of a single variable. The relationship between crop yields and the three drought indices varied by month, crop (maize and cotton), and timescale (3- and 6-month). The drought projections from our study can provide invaluable information for stakeholders in developing regionally specific drought adaptation strategies in the face of climate change.

Cadmium stress alters the redox reaction and hormone balance in oilseed rape (Brassica napus L.) leaves.

In order to understand the physiological response of oilseed rape (Brassica napus L.) leaves to cadmium (Cd) stress and exploit the physiological mechanisms involved in Cd tolerance, macro-mineral and chlorophyll concentrations, reactive oxygen species (ROS) accumulation, activities of enzymatic antioxidants, nonenzymatic compounds metabolism, endogenous hormonal changes, and balance in leaves of oilseed rape exposed to 0, 100, or 200 µM CdSO4 were investigated. The results showed that under Cd exposure, Cd concentrations in the leaves continually increased while macro-minerals and chlorophyll concentrations decreased significantly. Meanwhile, with increased Cd stress, superoxide anion (O2(• -)) production rate and hydrogen peroxide (H2O2) concentrations in the leaves increased significantly, which caused malondialdehyde (MDA) accumulation and oxidative stress. For scavenging excess accumulated ROS and alleviating oxidative injury in the leaves, the activity of enzymatic antioxidants, such as superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), was increased significantly at certain stress levels. However, with increased Cd stress, the antioxidant enzyme activities all showed a trend towards reduction. The nonenzymatic antioxidative compounds, such as proline and total soluble sugars, accumulated continuously with increased Cd stress to play a long-term role in scavenging ROS. In addition, ABA levels also increased continuously with Cd stress while ZR decreased and the ABA/ZR ratio increased, which might also be providing a protective role against Cd toxicity.