Recurrent predictive coding models for associative memory employing covariance learning.

The computational principles adopted by the hippocampus in associative memory (AM) tasks have been one of the most studied topics in computational and theoretical neuroscience. Recent theories suggested that AM and the predictive activities of the hippocampus could be described within a unitary account, and that predictive coding underlies the computations supporting AM in the hippocampus. Following this theory, a computational model based on classical hierarchical predictive networks was proposed and was shown to perform well in various AM tasks. However, this fully hierarchical model did not incorporate recurrent connections, an architectural component of the CA3 region of the hippocampus that is crucial for AM. This makes the structure of the model inconsistent with the known connectivity of CA3 and classical recurrent models such as Hopfield Networks, which learn the covariance of inputs through their recurrent connections to perform AM. Earlier PC models that learn the covariance information of inputs explicitly via recurrent connections seem to be a solution to these issues. Here, we show that although these models can perform AM, they do it in an implausible and numerically unstable way. Instead, we propose alternatives to these earlier covariance-learning predictive coding networks, which learn the covariance information implicitly and plausibly, and can use dendritic structures to encode prediction errors. We show analytically that our proposed models are perfectly equivalent to the earlier predictive coding model learning covariance explicitly, and encounter no numerical issues when performing AM tasks in practice. We further show that our models can be combined with hierarchical predictive coding networks to model the hippocampo-neocortical interactions. Our models provide a biologically plausible approach to modelling the hippocampal network, pointing to a potential computational mechanism during hippocampal memory formation and recall, which employs both predictive coding and covariance learning based on the recurrent network structure of the hippocampus.

Toll9 from Bombyx mori functions as a pattern recognition receptor that shares features with Toll-like receptor 4 from mammals.

Toll/Toll-like receptors (TLRs) are key regulators of the innate immune system in both invertebrates and vertebrates. However, while mammalian TLRs directly recognize pathogen-associated molecular patterns, the insect Toll pathway is thought to be primarily activated by binding Spätzle cytokines that are processed from inactive precursors in response to microbial infection. Phylogenetic and structural data generated in this study supported earlier results showing that Toll9 members differ from other insect Tolls by clustering with the mammalian TLR4 group, which recognizes lipopolysaccharide (LPS) through interaction with myeloid differentiation-2 (MD-2)-like proteins. Functional experiments showed that BmToll9 from the silkmoth Bombyx mori also recognized LPS through interaction with two MD-2-like proteins, previously named BmEsr16 and BmPP, that we refer to in this study as BmMD-2A and BmMD-2B, respectively. A chimeric BmToll9-TLR4 receptor consisting of the BmToll9 ectodomain and mouse TLR4 transmembrane and Toll/interleukin-1 (TIR) domains also activated LPS-induced release of inflammatory factors in murine cells but only in the presence of BmMD-2A or BmMD-2B. Overall, our results indicate that BmToll9 is a pattern recognition receptor for LPS that shares conserved features with the mammalian TLR4-MD-2-LPS pathway.

Differential Transcription Profiling Reveals the MicroRNAs Involved in Alleviating Damage to Photosynthesis under Drought Stress during the Grain Filling Stage in Wheat.

To explore the possible novel microRNA (miRNA) regulatory pathways in Zhengmai 1860, a newly cultivated drought-tolerant wheat (Triticum aestivum L.) cultivar, miRNA transcriptome sequencing of the flag leaves of Zhengmai 1860, drought-sensitive variety Zhoumai 18, and drought-resistant variety Bainong 207 was performed during the grain filling stage. We also observed changes in the chloroplast ultrastructure, phytohormone levels, and antioxidant- and photosynthesis-related physiological indicators in three wheat varieties. The results showed that the flag leaves of the drought-tolerant variety Zhengmai 1860 had higher chlorophyll contents and net photosynthetic rates than those of Zhoumai 18 under drought stress during the grain filling stage; in addition, the chloroplast structure was more complete. However, there was no significant difference between Zhengmai 1860 and Bainong 207. MiRNA transcriptome analysis revealed that the differential expression of the miRNAs and mRNAs exhibited variable specificity. The KEGG pathway enrichment results indicated that most of the genes were enriched in the MAPK signaling pathway, plant hormone signal transduction, photosynthetic antennae protein, and amino acid and carbohydrate metabolism. In the drought-tolerant cultivar Zhengmai 1860, tae-miR408 was targeted to regulate the allene oxide synthase (AOS) gene, inhibit its expression, reduce the AOS content, and decrease the synthesis of jasmonic acid (JA) and abscisic acid (ABA). The results of this study suggest that Zhengmai 1860 could improve the photosynthetic performance of flag leaves by inhibiting the expression of genes involved in the JA pathway through miRNAs under drought conditions. Moreover, multiple miRNAs may target chlorophyll, antioxidant enzymes, phytohormone signal transduction, and other related pathways; thus, it is possible to provide a more theoretical basis for wheat molecular breeding.

Reversible Emulsions from Polyoxometalate-Polymer: A Robust Strategy to Cyclic Emulsion Catalysis and High-Internal-Phase Emulsion Materials.

Reversible Pickering emulsions, achieved by switchable, interfacially active colloidal particles, that enable on-demand emulsification/demulsification or phase inversion, hold substantial promise for biphasic catalysis, emulsion polymerization, cutting fluids, and crude oil pipeline transportation. However, particles with such a responsive behavior usually require complex chemical syntheses and surface modifications, limiting their extensive use. Herein, we report a simple route to generate emulsions that can be controlled and reversibly undergo phase inversion. The emulsions are prepared and stabilized by the interfacial assembly of polyoxometalate (POM)-polymer, where their electrostatic interaction at the interface is dynamic. The wettability of the POMs that dictates the emulsion type can be readily regulated by tuning the number of polymer chains bound to POMs, which, in turn, can be controlled by varying the concentrations of both components and the water/oil ratio. In addition, the number of polymer chains anchored to the POMs can be varied by controlling the number of negative charges on the POMs through an in situ redox reaction. As such, a reversible inversion of the emulsions can be triggered by switching between exposure to ultraviolet light and the introduction of oxygen. Combining the functions of POM itself, a cyclic interfacial catalysis system was realized. Inversion of the emulsion also affords a pathway to high-internal-phase emulsions. The diversity of the POMs, the polymers, and the responsive switching groups open numerous new, simple strategies for designing a wide range of responsive soft matter for cargo loading, controlled release, and delivery in biomedical and engineering applications without time-consuming particle syntheses.

Synergistic Solar-Driven Freshwater Generation and Electricity Output Empowered by Wafer-Scale Nanostructured Silicon.

Electricity generation triggered by the ubiquitous water evaporation process provides an intriguing way to harvest energy from water. Meanwhile, natural water evaporation is also a fundamental way to obtain fresh water for human beings. Here, a wafer-scale nanostructured silicon-based device that takes advantage of its well-aligned configuration that simultaneously realizes solar steam generation (SSG) for freshwater collection and hydrovoltaic effect generation for electricity output is developed. An ingenious porous, black carbon nanotube fabric (CNF) electrode endows the device with sustainable water self-pumping capability, excellent durable conductivity, and intense solar spectrum harvesting. A combined device based on the CNF electrode integrated with nanostructured silicon nanowire arrays (SiNWs) provided an aligned numerous surface-to-volume water evaporation interface that enables a recorded continuous short-circuit current 8.65 mA and a water evaporation rate of 1.31 kg m-2 h-1 under one sun illumination. Such wafer-scale SiNWs-based SSG and hydrovoltaic integration devices would unchain the bottleneck of the weak and discontinuous electrical output of hydrovoltaic devices, which inspires other sorts of semiconductor-based hydrovoltaic device designs to target superior performance.

An electrochemiluminescence immunosensor based on multipath signal catalytic amplification integrated in a Cu2+-PEI-Pt/AuNC nanocomposite.

Here, the nanocomposite Cu2+-PEI-Pt/AuNCs with multipath signal catalytic amplification for a peroxydisulfate-dissolved oxygen electrochemiluminescence (ECL) system was prepared to fabricate a sensitive ECL immunosensor. Using polyethyleneimine (PEI), a linear polymer, as the reductant and template, Pt/Au nanochains (Pt/AuNCs) were prepared. Abundant PEI would adsorb on the surface of Pt/AuNCs via Pt-N or Au-N bonds, and further coordinate with Cu2+ to give the final nanocomposite Cu2+-PEI-Pt/AuNCs which possessed multipath signal catalytic amplification for the ECL of the peroxydisulfate-dissolved oxygen system in the presence of H2O2. First, PEI, as an effective co-reactant, could directly enhance the ECL intensity. Second, Pt/AuNCs could not only act as a mimicking enzyme to promote the decomposition of H2O2 to produce more oxygen in situ, but also act as an effective co-reaction accelerator to facilitate the generation of more co-reactive intermediate groups from peroxydisulfate, resulting in an obviously enhanced ECL signal. Then, Cu2+ could also accelerate the decomposition of H2O2 to produce more oxygen in situ, leading to a further improvement of the ECL response. Using Cu2+-PEI-Pt/AuNCs as a loading platform, a sandwiched ECL immunosensor was fabricated. As a result, the obtained ECL immunosensor possessed an ultra-sensitive detection performance for α-1-fetoprotein, providing effective information on the diagnosis and treatment of related diseases.

Vertical distributions and potential sources of wintertime atmospheric pollutants and the corresponding ozone production on the coast of Bohai Sea.

This study investigated the wintertime vertical distributions and source areas of aerosols, NO2, and HCHO in a coastal city of Dongying from December 2020 to March 2021, using ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) and a potential source contribution function (PSCF) model, respectively. Moreover, the chemical production sensitivity of O3 at different height layers was analyzed using HCHO/NO2 ratios. The results revealed that the wintertime averaged highest concentrations of aerosol (1.25 km-1), NO2 (14.81 ppb), and HCHO (2.32 ppb) were mainly distributed at the surface layer, 100-200 m layer, and 200-300 m layer, respectively. Regarding the diurnal cycles, high concentrations of aerosol (>1.4 km-1) and NO2 (>16.0 ppb) usually appeared in the early morning and late afternoon, while high concentrations of HCHO (>2.5 ppb) usually occurred during 12:00-15:00. The PSCF model revealed that the wintertime aerosol mainly originated from Shandong, northern Jiangsu, Korea, and the northwestern Mongolian Plateau. Below 200 m, NO2 was mainly from western Shandong, whereas above 600 m, it was mainly from northern Shandong and the Beijing-Tianjin-Hebei (BTH) region. The corresponding sources for HCHO were central and southern Shandong (below 200 m) and northern Shandong, northern Jiangsu, and southeastern BTH (above 600 m). In addition, the chemical production sensitivity of O3 below 100 m was observed only in the VOC-limited regime. The percentages of O3 production under the NOx-limited, NOx-VOC-limited, and VOC-limited regimes were 10.75% (31.18%), 4.30% (19.35%), and 84.95% (49.47%) at the 500-600 m (900-1000 m) layer. This study has guiding significance for the coordinated control of PM2.5 and O3, and can assist in the implementation of regional joint prevention and control strategies for air pollutants.

Cationic P,O-Coordinated Nickel(II) Catalysts for Carbonylative Polymerization of Ethylene: Unexpected Productivity via Subtle Electronic Variation.

Transition-metal-catalyzed copolymerization of ethylene with carbon monoxide affords polyketones materials with excellent mechanical strength, photodegradability, surface and barrier properties. Unlike the widely used and rather expensive Pd catalysts, Ni-catalyzed carbonylative polymerization is very difficult since the strong binding affinity of CO to Ni deactivates the highly electrophilic metal center easily. In this study, various cationic P,O-coordinated Ni complexes were synthesized using the electronic modulation strategy, and the catalyst with strong electron-donating substituents exhibits an excellent productivity of 104  g polymer (g Ni)-1 , which represents a rare discovery that a Ni complex could operate with such exceptional efficiency in comparison with Pd catalysts. Notably, those Ni catalysts were also efficient for terpolymerization of ethylene, propylene with CO for producing commercial polyketone materials with low melting temperatures and easy processibility.

Preparation of a silver nano-tripod structure by a tilting angle deposition technique and its SERS application.

A silver nano-tripod (AgNT) structure with a high-density "hot spots" distribution was fabricated by a tilting angle deposition technique. The electric field simulation distribution showed that the electric field enhancement of the AgNT structures is optimal when the tilting angle is 72°. Such AgNT substrates were successfully obtained experimentally when the included angle between the silver vapor and the normal of the sample platform was set to 86°. R6G and CV were used as probe molecules to investigate the SERS activity of AgNT, which revealed that the detection limits of AgNT for R6G and CV were 2.24×10-8 M and 4.01×10-8 M, the relative standard deviations (RSDs) were 4.26% and 4.44%, and the enhancement factors (EFs) were 9.58×106 and 1.16×107, respectively. The AgNT substrates with simple preparation and high distribution density of "hot spots" illustrate a good application prospect in environmental monitoring.

Two-dimensional MXene modified AgNRs as a surface-enhanced Raman scattering substrate for sensitive determination of polychlorinated biphenyls.

Ultrathin two-dimensional MXene nanosheets were decorated on the surface of silver nanorods (AgNRs) through a facile modification strategy to prepare highly sensitive and reproducible SERS substrates (AgNR/MXene substrate). The MXene nanosheets could suppress the oxidation of the silver nanorods, which endows the substrate with good stability and reproducibility. Due to the strong interaction between AgNR/MXene and the analytes, the substrate also exhibited high SERS performance with the limit of detection (LOD) of crystal violet (CV) as low as 2.48 × 10-11 M. In particular, the AgNR/MXene substrate enabled on-site determination of 3,3',4,4'-tetrachlorobiphenyl (PCB-77) and 4-chlorobiphenyl (PCB-3) and the LODs were low at 2.43 × 10-10 and 2.14 × 10-9 M, respectively. In addition, the AgNR/MXene substrate could be used for the detection of single-component and multi-component PCBs in real soil samples with good recovery percentages (90.3% and 91.6% for PCB-3 and PCB-77 in single-component format, 108.1% and 106.5% for PCB-3 and PCB-77 in multi-component format). The AgNR/MXene substrate combines the synergistic properties of both AgNRs and MXene, showing great potential in simultaneous SERS detection of multiple pollutants at the point of need.

Directly modulated green-light diode-pumped solid-state laser for underwater wireless optical communication.

It is widely known that a diode-pumped solid-state laser (DPSSL) has very limited modulation bandwidth. Recently, we directed our attention toward the opportunities for directly modulating a DPSSL to generate high-speed green-light signals, with high power and superior beam quality, which are highly desirable in underwater wireless optical communication. The constraint imposed by the limited modulation bandwidth of a DPSSL is circumvented with the strategy of orthogonal frequency-division multiplexing and power loading. With a compact DPSSL dismantled from a low-cost laser pointer, we achieve net bit rates of 108.55 Mb/s for the 64 quadrature amplitude modulation (QAM) signal at a bit error rate (BER) of 6.42×10-4 and 89.55 Mb/s for the 32 QAM signal at a BER of 4.81×10-4, respectively, over a 2 m underwater channel. When the underwater transmission distance is increased to 6 m, the BERs are still below the forward error correction (FEC) limit of 3.8×10-3.

Underwater wireless transmission of high-speed QAM-OFDM signals using a compact red-light laser.

We first study the transmission property of red light in water in terms of extinction coefficient and channel bandwidth via Monte Carlo simulation, with an interesting finding that red light outperforms blue-green light in highly turbid water. We further propose and experimentally demonstrate a broadband underwater wireless optical communication system based on a simple and cost-effective TO56 red-light laser diode. We demonstrate a 1.324-Gb/s transmission at a bit error rate (BER) of 2.02 × 10-3 over a 6-m underwater channel, by using 128-QAM OFDM signals and a low-cost 150-MHz positive-intrinsic-negative photodetector, with a record spectral efficiency higher than 7.32 bits/Hz. By using an avalanche photodetector and 32-QAM OFDM signals, we have achieved a record bit rate of 4.883 Gb/s at a BER of 3.20 × 10-3 over a 6-m underwater channel.

Production of trans-10,cis-12-conjugated linoleic acid using permeabilized whole-cell biocatalyst of Yarrowia lipolytica.

OBJECTIVE: To improve the production of trans-10,cis-12-conjugated linoleic acid (t10,c12-CLA) from linoleic acid in recombinant Yarrowia lipolytica. RESULTS: Cells of the yeast were permeabilized by freeze/thawing. The optimal conditions for t10,c12-CLA production by the permeabilized cells were at 28 °C, pH 7, 200 rpm with 1.5 g sodium acetate l-1, 100 g wet cells l-1, and 25 g LA l-1. Under these conditions, the permeabilized cells produced 15.6 g t10,c12-CLA l-1 after 40 h, with a conversion yield of 62 %. The permeabilized cells could be used repeatedly for three cycles, with the t10,c12-CLA extracellular production remaining above 10 g l-1. CONCLUSION: Synthesis of t10,c12-CLA was achieved using a novel method, and the production reported in this work is the highest value reported to date.

Research on Predicting the Turnover of Graduates Using an Enhanced Random Forest Model.

The frequent turnover of college graduates is a key factor leading to the frictional unemployment and structural unemployment of youth, which are important research fields concerned with pedagogy, sociology, and management; however, there is little research on the prediction of college graduates' turnover. Therefore, this study investigated the turnover status of 17,268 college graduates from 52 universities in China, constructed and optimized a random forest model for predicting the turnover of college graduates, and analyzed the influencing mechanism of college graduates' turnover and the importance of influencing factors. The enhanced random forest model could deal with the unbalanced data and has a higher prediction accuracy as well as stronger generalization ability in predicting the turnover of college graduates. Individual background variables, job characteristic variables, and work environment variables are all important factors influencing whether college graduates resign or not. The top five factors that affect the turnover of college graduates by more than 10% are income level, job satisfaction degree, job opportunities, and job matching degree. The conclusion of this study is conducive to improving the accuracy of turnover prediction, systematically exploring the influencing factors of college graduates' turnover, and effectively guaranteeing the overall stability of youth employment.

Inferring neural activity before plasticity as a foundation for learning beyond backpropagation.

For both humans and machines, the essence of learning is to pinpoint which components in its information processing pipeline are responsible for an error in its output, a challenge that is known as 'credit assignment'. It has long been assumed that credit assignment is best solved by backpropagation, which is also the foundation of modern machine learning. Here, we set out a fundamentally different principle on credit assignment called 'prospective configuration'. In prospective configuration, the network first infers the pattern of neural activity that should result from learning, and then the synaptic weights are modified to consolidate the change in neural activity. We demonstrate that this distinct mechanism, in contrast to backpropagation, (1) underlies learning in a well-established family of models of cortical circuits, (2) enables learning that is more efficient and effective in many contexts faced by biological organisms and (3) reproduces surprising patterns of neural activity and behavior observed in diverse human and rat learning experiments.

Myc rearrangement redefines the stratification of high-risk multiple myeloma.

BACKGROUND: Myc rearrangement (Myc-R) is a controversial factor linked to adverse outcomes in newly diagnosed multiple myeloma (NDMM). AIMS: This study aimed to evaluate the impact of Myc-R on the prognosis of NDMM patients and its role in risk stratification compared with traditional high-risk cytogenetic abnormalities (HRCAs). MATERIALS & METHODS: A total of 417 NDMM patients enrolled from May 2009 to September 2022 were included. Fluorescence in situ hybridization (FISH) was used to detect Myc-R and other Myc abnormalities (Myc-OA). Median progression-free survival (PFS) and overall survival (OS) were analyzed using Kaplan-Meier methods and log-rank tests. Multivariate Cox regression analysis was used to identify independent risk factors. RESULTS: Myc-R was identified in 13.7% of patients, while 14.6% had Myc-OA. Patients with Myc-R had significantly shorter median PFS (15.9 months) and OS (25.1 months) compared with those with Myc-OA (24.5 months PFS; 29.8 months OS) and Myc-negative (Myc-N) status (29.8 months PFS, 29.8 months OS). Myc-R was independently associated with worse PFS and OS compared to Myc-OA. Patients with Myc-R alone had inferior median PFS (15.9 months vs. 28.1 months, p = 0.032) and OS (25.1 months vs. 61.2 months, p = 0.04) compared to those with traditional single HRCA. DISCUSSION: The study suggests that traditional single HRCA may not significantly impact survival in NDMM patients. However, incorporating Myc rearrangement or traditional double/triple-hit HRCAs into the risk stratification model improves its predictive value, highlighting the importance of Myc rearrangement in risk assessment. CONCLUSION: Myc rearrangement is an independent adverse prognostic factor in NDMM. The incorporation of Myc rearrangement or multiple HRCAs into risk stratification models improves their prognostic value, providing a novel perspective on high-risk factors in NDMM.

Effects of Tea Plant Varieties with High- and Low-Nutrient Efficiency on Nutrients in Degraded Soil.

Tea plants are widely planted in tropical and subtropical regions globally, especially in southern China. The high leaching and strong soil acidity in these areas, in addition to human factors (e.g., tea picking and inappropriate fertilization methods) aggravate the lack of nutrients in tea garden soil. Therefore, improving degraded tea-growing soil is urgently required. Although the influence of biological factors (e.g., tea plant variety) on soil nutrients has been explored in the existing literature, there are few studies on the inhibition of soil nutrient degradation using different tea plant varieties. In this study, two tea plant varieties with different nutrient efficiencies (high-nutrient-efficiency variety: Longjing43 (LJ43); low-nutrient-efficiency variety: Liyou002 (LY002)) were studied. Under a one-side fertilization mode of two rows and two plants, the tea plant growth status, soil pH, and available nutrients in the soil profiles were analyzed, aiming to reveal the improvement of degraded soil using different tea varieties. The results showed that (1) differences in the phenotypic features of growth (such as dry tea yield, chlorophyll, leaf nitrogen (N), phosphorus (P), and potassium (K) content) between the fertilization belts in LJ43 (LJ43-near and LJ43-far) were lower than those in LY002. (2) RDA results showed that the crucial soil nutrient factors which determine the features of tea plants included available P, slowly available K, and available K. Moreover, acidification was more serious near the fertilization belt. The pH of the soil near LJ43 was higher than that near LY002, indicating an improvement in soil acidification. (3) Soil nutrient heterogeneity between fertilization belts in LJ43 (LJ43-near and LJ43-far) was lower than in LY002. In conclusion, the long-term one-side fertilization mode of two rows and two plants usually causes spatial heterogeneities in soil nutrients and aggravates soil acidification. However, LJ43 can reduce the nutrient heterogeneities and soil acidification, which is probably due to the preferential development of secondary roots. These results are helpful in understanding the influence of tea plant variety on improving soil nutrients and provide a relevant scientific reference for breeding high-quality tea varieties, improving the state of degraded soil and maintaining soil health.

A review of different breast reconstruction methods.

Breast reconstruction is necessary for the comprehensive treatment of breast cancer. For successful breast reconstruction, the timing of surgery and the surgical methods used are vital. The methods of breast reconstruction can be divided into implant-based breast reconstruction (IBBR) and autologous breast reconstruction (ABR). With the development of acellular dermal matrix (ADM), IBBR has become more common in clinical practice. However, the choice for the position in which the implant should be placed (prepectoral or subpectoral) and the use of ADM is currently controversial. We summarized the differences in indications, complications, advantages, disadvantages, and prognosis between IBBR and ABR. We also compared the indications and complications of different flaps in ABR and found that the LD (latissimus dorsi) flap is suitable for Asian women who have a low body mass index (BMI) and a low incidence of obesity, while the DIEP (deep inferior epigastric perforator) flap can be used in patients with severe breast ptosis. In conclusion, immediate breast reconstruction with an implant or expander is the primary method, as it causes lesser scarring and requires a shorter time compared to ABR. However, for patients with severe breast ptosis or reluctant to receive an implant, ABR can be performed for a satisfying cosmetic result. Indications and complications of different flaps in ABR are also inconsistent. Surgeons should make surgical plans based on the preferences and conditions of each patient. In the future, breast reconstruction methods need to be further refined, and minimally invasive and personalized approaches need to be implemented to provide more benefits to patients.

Unraveling Deposition Atmosphere Impact on Reproducibility of Perovskite Light-Emitting Diodes.

Manipulating the crystallization dynamics of perovskite emitters is an effective strategy for preparing high-performance perovskite light-emitting diodes (PeLEDs). In general, amorphous-like thermodynamically stable intermediates are desirable for a retarded and controllable crystallization process of perovskite emitters. Despite a variety of well-demonstrated strategies for crystallization control, it has been generally realized that perovskite thin-film emitters show problematic reproducibility. Here, we unraveled that the coordinating solvent vapor residues could raise deleterious influences on the formation of amorphous intermediate phases, which thus leads to varying crystal qualities from batch to batch. We demonstrated that undesirable crystalline intermediate phases tend to form with a strong coordination solvent vapor atmosphere, which alters the crystallization process and thus brings about additional ionic defects. By applying an inert gas flush strategy, this detrimental effect could be effectively mitigated, enabling PeLEDs with high reproducibility. This work provides new insight into the fabrication of efficient and reproducible perovskite optoelectronics.

Long-term observations of NO2 using GEMS in China: Validations and regional transport.

In 2019, South Korea launched the Geostationary Environment Monitoring Spectrometer (GEMS) to observe trace gases with an hourly temporal resolution. Compared to previous payloads on polar-orbiting satellites, the GEMS payload has significant advantages in detecting the diurnal variation characteristics of NO2. However, there is still a lack of ground-based validations regarding the overall accuracy of GEMS in the Chinese region. In this study, we conducted a systematic ground validation of GEMS NO2 data in China for the first time. We validated the accuracy of GEMS NO2 data in four typical pollution regions in China, namely the Beijing-Tianjin-Hebei region (JJJ), the Yangtze River Delta region (YRD), the Pearl River Delta region (PRD), and the Sichuan Basin region (SCB), based on MAX-DOAS and CNEMC data. The averaged correlations using the two datasets for validation were 0.81 and 0.57, respectively, indicating a high level of accuracy for the data in China. Using the GEMS seasonal averaged NO2 data, we studied the distribution of NO2 levels in the four regions. We found that the highest NO2 in all four regions occurred during winter with concentrations of 1.84 × 1016 molecules cm-2, 1.59 × 1016 molecules cm-2, 1.58 × 1016 molecules cm-2 and 9.47 × 1015 molecules cm-2, respectively. The distribution of NO2 was closely related to the terrain. Additionally, we observed a significant underestimation issue with TROPOMI, exceeding 30 % in many regions. Based on MAX-DOAS, we investigated the vertical distribution of NO2 in the four regions and found that NO2 was mainly concentrated below 0.5 km. with the HNU station having the lowest concentration, averaging only 2.12 ppb, which was approximately 41 % of the highest concentration recorded at the CQ station. Furthermore, we conducted a study on regional and cross-regional transport using a combination of MAX-DOAS and GEMS data. We found that the transport flux of NO2 could increase by over 500 % within 1 h, making a significant contribution to local NO2 concentrations. The joint observations of GEMS and MAX-DOAS will provide reliable data support for NO2 research and control in China, making a substantial contribution to environmental protection and sustainable development.