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NO[sub.2] primarily originates from natural and anthropogenic emissions. Given China’s vast territory and significant differences in topography and meteorological conditions, a detailed understanding of the impacts of weather and human emissions in different regions is essential. This study employs Kolmogorov–Zurbenko (KZ) filtering and stepwise multiple linear regression to isolate the effects of meteorological conditions on tropospheric NO[sub.2] vertical column densities. Long term trends indicate an overall decline, with anthropogenic contribution rates exceeding 90% in Shanghai, Changchun, Urumqi, Shijiazhuang, and Wuhan, where interannual variations are primarily driven by human emissions. In Guangzhou, the anthropogenic contribution rate exceeds 100%, highlighting the significant impact of human factors in this region, although meteorological conditions somewhat mitigate their effect on NO[sub.2]. In Chengdu, meteorological factors also play a role. Seasonal variations display a U-shaped trend, and there are significant differences in the impact of meteorological factors on seasonal variations among different regions. Meteorological contribution rates in Changchun and Chengdu are below 36.90% and anthropogenic contributions exceed 63.10%. This indicates that changes in NO[sub.2] are less influenced by meteorological factors than by human activities, with human emissions dominating. In other regions, meteorological contributions are greater than those from human activities.

The field of lipidomics has been significantly advanced by mass spectrometric analysis. The distinction and quantitation of the unsaturated lipid isomers, however, remain a long-standing challenge. In this study, we have developed an analytical tool for both identification and quantitation of lipid C=C location isomers from complex mixtures using online Paternò–Büchi reaction coupled with tandem mass spectrometry (MS/MS). The potential of this method has been demonstrated with an implementation into shotgun lipid analysis of animal tissues. Among 96 of the unsaturated fatty acids and glycerophospholipids identified from rat brain tissue, 50% of them were found as mixtures of C=C location isomers; for the first time, to our knowledge, the quantitative information of lipid C=C isomers from a broad range of classes was obtained. This method also enabled facile cross-tissue examinations, which revealed significant changes in C=C location isomer compositions of a series of fatty acids and glycerophospholipid (GP) species between the normal and cancerous tissues.

Heterojunction creation is demonstrated as an effective strategy to enhance the transfer and separation of charge carriers, which is beneficial for subsequent photocatalytic reactions. In this study, “sea urchin-like” W[sub.18]O[sub.49] was in situ-grown on the surface of Bi[sub.12]GeO[sub.20] through a hydrothermal process, and the released Cl[sup.−] anions tended to produce BiOCl simultaneously. Systematical characterizations confirmed the construction of ternary composites Bi[sub.12]GeO[sub.20]/BiOCl/W[sub.18]O[sub.49] (GBW), in which Type I and Z-scheme models were integrated to promote charge carrier migration and separation by combining the structural merits of both models. Under UV–visible light, the catalytic performance of the as-synthesized samples was tested in terms of NO oxidation removal. Compared to pure Bi[sub.12]GeO[sub.20], the composite GBW5 showed the highest NO photocatalytic removal efficiency of 42%, which was nearly four times that of pure Bi[sub.12]GeO[sub.20]. These improvements were mainly due to enhanced light absorption, suitable morphological features, effective separation of charge carriers, and the boosted generation of reactive species in the GBW series. This study paves the way for the construction of Bi[sub.12]GeO[sub.20]-based ternary composites using a comprehensive utilization of waste method and the employment of the composites for the photocatalytic removal of low concentrations of NO at the ppb level.

A novel g-C 3 N 4 nanoparticle@porous g-C 3 N 4 (CNNP@PCN) composite has been successfully fabricated by loading g-C 3 N 4 nanoparticles on the porous g-C 3 N 4 matrix via a simply electrostatic self-assembly method. The composition, morphological structure, optical property, and photocatalytic performance of the composite were evaluated by various measurements, including XRD, SEM, TEM, Zeta potential, DRS, PL, FTIR, and XPS. The results prove that the nanolization of g-C 3 N 4 leads to an apparent blueshift of the absorption edge, and the energy band gap is increased from 2.84 eV of porous g-C 3 N 4 to 3.40 eV of g-C 3 N 4 nanoparticle (Fig. 6). Moreover, the valence band position of the g-C 3 N 4 nanoparticle is about 0.7 eV lower than that of porous g-C 3 N 4 . Therefore, the photo-generated holes and electrons in porous g-C 3 N 4 can transfer to the conduction band of g-C 3 N 4 nanoparticle, thereby obtaining higher separation efficiency of photo-generated carriers as well as longer carrier lifetime. Under visible-light irradiation, 6CNNP@PCN exhibits the highest photocatalytic performance (Fig. 8) on MB, which is approximately 3.4 times as that of bulk g-C 3 N 4 .

High denitration efficiency and strong adaptability to flue gas temperature fluctuations are the core properties of the NH[sub.3]-SCR catalyst. In this study, Fe[sub.2]O[sub.3] modification is used as a means to explore the mechanism of adding Fe[sub.2]O[sub.3] to broaden the temperature range of the 6CeO[sub.2]-40MnO[sub.2]/TiO[sub.2] catalyst during the preparation process. The results show that the 6Fe[sub.2]O[sub.3]-6CeO[sub.2]-40MnO[sub.2]/TiO[sub.2] catalyst exhibits excellent denitration performance, with a denitration efficiency higher than 90%. The temperature range is from 129 to 390 °C. N[sub.2] selectivity and resistance to SO[sub.2] and H[sub.2]O are good, and the denitration performance is significantly improved. When the Fe[sub.2]O[sub.3] content is 6%, it promotes lattice shrinkage of TiO[sub.2], improves its dispersion, refines the grain size, and increases the specific surface area of the catalyst. At the same time, Fe[sub.2]O[sub.3] enhances the chemical adsorption of oxygen on the catalyst surface and increases the proportion of low-cost metal ions, thereby promoting electron transfer between active elements, generating more surface reactive oxygen species, increasing the oxygen vacancy content and adsorption sites for NO[sub.x] and NH[sub.3], and significantly improving the redox performance of the catalyst. This effect is particularly conducive to the formation of strong acid sites on the catalyst surface. The NH[sub.3]-SCR reaction on the surface of the 6Fe[sub.2]O[sub.3]-6CeO[sub.2]-40MnO[sub.2]/TiO[sub.2] catalyst follows both the L-H and E-R mechanisms, with the L-H mechanism being dominant.

In contrast to the wealth of catalytic systems that are available to control the stereochemistry of thermally promoted cycloadditions, few similarly effective methods exist for the stereocontrol of photochemical cycloadditions. A major unsolved challenge in the design of enantioselective catalytic photocycloaddition reactions has been the difficulty of controlling racemic background reactions that occur by direct photoexcitation of substrates while unbound to catalyst. Here, we describe a strategy for eliminating the racemic background reaction in asymmetric [2 + 2] photocycloadditions of α,β-unsaturated ketones to the corresponding cyclobutanes by using a dual-catalyst system consisting of a visible light–absorbing transition-metal photocatalyst and a stereocontrolling Lewis acid cocatalyst. The independence of these two catalysts enables broader scope, greater stereochemical flexibility, and better efficiency than previously reported methods for enantioselective photochemical cycloadditions.

The implementation of continuous flow technology is critical towards enhancing the application of photochemical reactions for industrial process development. However, there are significant time and resource constraints associated with translating discovery scale vial-based batch reactions to continuous flow scale-up conditions. Herein we report the development of a droplet microfluidic platform, which enables high-throughput reaction discovery in flow to generate pharmaceutically relevant compound libraries. This platform allows for enhanced material efficiency, as reactions can be performed on picomole scale. Furthermore, high-throughput data collection via on-line ESI mass spectrometry facilitates the rapid analysis of individual, nanoliter-sized reaction droplets at acquisition rates of 0.3 samples/s. We envision this high-throughput screening platform to expand upon the robust capabilities and impact of photochemical reactions in drug discovery and development. Translating discovery scale vial-based batch reactions to continuous flow scale-up conditions is limited by significant time and resource constraints. Here, the authors report a photochemical droplet microfluidic platform, which enables high throughput reaction discovery in flow to generate pharmaceutically relevant compound libraries.

Many applications of plasmonic nanoparticles require precise control of their optical properties that are governed by nanoparticle dimensions, shape, morphology and composition. Finding reaction conditions for the synthesis of nanoparticles with targeted characteristics is a time-consuming and resource-intensive trial-and-error process, however closed-loop nanoparticle synthesis enables the accelerated exploration of large chemical spaces without human intervention. Here, we introduce the Autonomous Fluidic Identification and Optimization Nanochemistry (AFION) self-driving lab that integrates a microfluidic reactor, in-flow spectroscopic nanoparticle characterization, and machine learning for the exploration and optimization of the multidimensional chemical space for the photochemical synthesis of plasmonic nanoparticles. By targeting spectroscopic nanoparticle properties, the AFION lab identifies reaction conditions for the synthesis of different types of nanoparticles with designated shapes, morphologies, and compositions. Data analysis provides insight into the role of reaction conditions for the synthesis of the targeted nanoparticle type. This work shows that the AFION lab is an effective exploration platform for on-demand synthesis of plasmonic nanoparticles. The automated synthesis of plasmonic nanoparticles with on-demand properties is a challenging task. Here the authors integrate a fluidic reactor, real-time characterization, and machine learning in a self-driven lab for the photochemical synthesis of nanoparticles with targeted properties.

A recently discovered family of natural anion channelrhodopsins (ACRs) have the highest conductance among channelrhodopsins and exhibit exclusive anion selectivity, which make them efficient inhibitory tools for optogenetics. We report analysis of flash-induced absorption changes in purified wild-type and mutant ACRs, and of photocurrents they generate in HEK293 cells. Contrary to cation channelrhodopsins (CCRs), the ion conducting state of ACRs develops in an L-like intermediate that precedes the deprotonation of the retinylidene Schiff base (i.e., formation of an M intermediate). Channel closing involves two mechanisms leading to depletion of the conducting L-like state: (i) Fast closing is caused by a reversible L⇔M conversion. Glu-68 in Guillardia theta ACR1 plays an important role in this transition, likely serving as a counterion and proton acceptor at least at high and neutral pH. Incomplete suppression of M formation in the GtACR1_E68Q mutant indicates the existence of an alternative proton acceptor. (ii) Slow closing of the channel parallels irreversible depletion of the M-like and, hence, L-like state.Mutation of Cys-102 that strongly affected slow channel closing slowed the photocycle to the same extent. The L and M intermediates were in equilibrium in C102A as in the WT. In the position of Glu-123 in channelrhodopsin-2, ACRs contain a noncarboxylate residue, the mutation of which to Glu produced early Schiff base proton transfer and strongly inhibited channel activity. The data reveal fundamental differences between natural ACR and CCR conductance mechanisms and their underlying photochemistry, further confirming that these proteins form distinct families of rhodopsin channels.