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Injecting fluids into the subsurface frequently triggers earthquakes, yet the maximum size of these events remains difficult to forecast. Earthquake frequencies are typically assumed to decay exponentially with magnitude, a model that fits natural seismicity well. Here, we use a global compilation of injection-induced sequences to show that this model breaks down for about half of the cases, which instead show a downturn in the occurrence of larger events. Numerical simulations and observed spatial patterns of induced seismicity suggest that heterogeneous loading near injection sites and disorganized fault networks may limit the growth of large ruptures. These results provide a possible explanation for why induced earthquakes often remain below magnitude 2–3 and provide a basis for evaluating seismic hazard before and during injection operations. This study shows that earthquakes caused by fluid injection are often smaller than expected. Combining data and simulations, it links this to heterogeneous stress near wells and structural limits of fault networks.

The conversion of inexpensive aqueous ammonia (NH 3 ·H 2 O) into value-added primary amines by N−H insertion persists as a longstanding challenge in chemistry because of the tendency of Lewis basic ammonia (NH 3 ) to bind and inhibit metal catalysts. Herein, we report a chemoselective carbene N−H insertion of NH 3 ·H 2 O using a Tp Br3 Ag-catalyzed two-phase system. Coordination by a homoscorpionate Tp Br3 ligand renders silver compatible with NH 3 and H 2 O and enables the generation of electrophilic silver carbene. Water promotes subsequent [1,2]-proton shift to generate N−H insertion products with high chemoselectivity. The result of the reaction is the coupling of an inorganic nitrogen source with either diazo compounds or N- triftosylhydrazones to produce useful primary amines. Further investigations elucidate the reaction mechanism and the origin of chemoselectivity. Converting low-cost inorganic chemicals into value-added organic chemicals is a longstanding goal in chemistry. Here the authors describe a silver-catalysed chemoselective carbene N−H insertion reaction, providing access to primary amines from aqueous ammonia and diazo compounds.

Epoxides, as a prominent small ring O -heterocyclic and the privileged pharmacophores for medicinal chemistry, have recently represented an ideal substrate for the development of single-atom replacements. The previous O -to- C replacement strategy for epoxides to date typically requires high temperatures to achieve low yields and lacks substrate range and functional group tolerance, so achieving this oxygen-carbon exchange remains a formidable challenge. Here, we report a silver-catalyzed direct conversion of epoxides into trifluoromethylcyclopropanes in a single step using trifluoromethyl N -triftosylhydrazones as carbene precursors, thereby achieving oxygen-carbon exchange via a tandem deoxygenation/[2 + 1] cycloaddition. The reaction shows broad tolerance of functional groups, allowing routine cheletropic olefin synthesis in a strategy for the net oxygen-carbon exchange reaction. The utility of this method is further showcased with the late-stage diversification of epoxides derived from bioactive natural products and drugs. Mechanistic experiments and DFT calculations elucidate the reaction mechanism and the origin of the chemo- and stereoselectivity. Epoxides are prominent small-ring O -heterocycles found in a variety of bioactive natural products and pharmaceuticals. Here, the authors report a silver carbene strategy to achieve O-to-C atom exchange of epoxides in a single step, affording diverse fluoroalkylcyclopropanes.

The C–F bond cleavage and C–C bond formation (i.e., carbodefluorination) of readily accessible (per)fluoroalkyl groups constitutes an atom-economical and efficient route to partially fluorinated compounds. However, the selective mono-carbodefluorination of trifluoromethyl (CF 3 ) groups remains a challenge, due to the notorious inertness of C–F bond and the risk of over-defluorination arising from C–F bond strength decrease as the defluorination proceeds. Herein, we report a carbene-initiated rearrangement strategy for the carbodefluorination of fluoroalkyl ketones with β,γ-unsaturated alcohols to provide skeletally and functionally diverse α-mono- and α,α-difluoro-γ,δ-unsaturated ketones. The reaction starts with the formation of silver carbenes from fluoroalkyl N -triftosylhydrazones, followed by nucleophilic attack of a β,γ-unsaturated alcohol to form key silver-coordinated oxonium ylide intermediates, which triggers selective C–F bond cleavage by HF elimination and C–C bond formation through Claisen rearrangement of in situ generated difluorovinyl ether. The origin of chemoselectivity and the reaction mechanism are determined by experimental and DFT calculations. Collectively, this strategy by an intramolecular cascade process offers significant advances over existing stepwise strategies in terms of selectivity, efficiency, functional group tolerance, etc. The selective functionalization of trifluoromethyl groups is challenging due to the inertness of the C–F bonds. Here the authors report a method for the carbodefluorination of C–F bonds of fluoroalkyl ketones via a carbene-initiated rearrangement strategy.

The paper presents an improved Komodo Mlipir Algorithm (KMA) with variable inertia weight and chaos mapping (VWCKMA). In contrast to the original Komodo Mlipir Algorithm (KMA), the chaotic sequence initialization population generated by Tent mapping and Tent Chaos disturbance used in VWCKMA can effectively prevent the algorithm from falling into a local optimal solution and enhance population diversity. Individuals of different social classes can be controlled by the variable inertia weight, and the convergence speed and accuracy can be increased. For the purpose of evaluating the performance of the VWCKMA, function optimization and actual predictive optimization experiments are conducted. As a result of the simulation results, the convergence accuracy and convergence speed of the VWCKMA have been considerably enhanced for single-peak, multi-peak, and fixed-dimensional complex functions in different dimensions and even thousands of dimensions. To address the nonlinearity of PM2.5 prediction in practical problems, the weights and thresholds of the BP neural network were iteratively optimized using VWCKMA, and the BP neural network was then used to predict PM2.5 using the optimal parameters. Experimental results indicate that the accuracy of the VWCKMA-optimized BP neural network model is 85.085%, which is 19.85% higher than that of the BP neural network, indicating that the VWCKMA has a certain practical application.

As the global population grows, food security and agricultural productivity face challenges, and insect pests cause significant losses to crops. The effectiveness of traditional chemical pesticides is declining, and eco-friendly pesticides need to be developed. Diterpenoid alkaloids (DAs), natural products of plant origin, have attracted attention due to their low environmental risks. Here we review the classification, structure, insecticidal and anti-feeding activities of diterpenoid alkaloids, as well as the current state of research on these chemicals. Studies have shown that C19- and C20-diterpenoid alkaloids show significant activity against a variety of insects, but there are still limited studies on C18-diterpenoid alkaloids. Therefore, through in-depth research on diterpenoid alkaloids, we have discovered that there are various compounds with high efficiency and specificity in insecticidal and antifeedant activities among C19- and C20-diterpenoid alkaloids, which exhibit high selectivity and efficiency towards target pests. This paper emphasizes the potential of diterpenoid alkaloids as novel biopesticides and highlights the need to combine new technologies to conduct further systematic evaluation and screening of these compounds. This work provides new ideas for the development of environmentally friendly pesticides and contributes to sustainable agricultural practices.

The scalable synthesis of high-quality graphite materials remains a formidable challenge due to the inherent trade-off between crystalline perfection and manufacturing efficiency. Existing forms of graphite, such as highly oriented pyrolytic graphite (HOPG) and Kish graphite, suffer from sluggish pyrolytic processes, limited carbon diffusion rates and energy-intensive protocols, often requiring several days for production. Here, we report a pulsed Joule heating-induced carburization (PJHIC) strategy that exploits transient non-equilibrium states to enable rapid carbon diffusion and segregation in metal substrates. By applying instantaneous thermal shocks ( > 1300 °C, > 300 °C/s heating rate) to solid carbon precursor-coated nickel and cobalt foils, we demonstrate the rapid carbon transport in bulk metals and achieve a vertical graphite growth rate of 730 nm/min, which is an order of magnitude faster than conventional methods. Cyclic temperature pulses further enable the synthesis of 1–5 μm-thick ABA-stacked graphite films with millimeter-scale grain sizes. The resulting rapid epitaxially grown graphite films exhibit a highly ordered crystalline structure and exceptional thermal conductivity (1314 W m –1 K –1 ), comparable to high-quality HOPG and Kish graphite. This work establishes a non-equilibrium synthesis paradigm for high-quality layered materials, bridging atomic-scale precision with industrial-scale manufacturing. Here, a pulsed Joule heating strategy for the synthesis of high-quality graphite is developed achieving a growth rate of up to 730 nm min -1 , an order of magnitude faster than conventional approaches, and producing large-area films with excellent thermal conductivity.

NRC publication: Yes

Cell-free DNA (cfDNA) consists of degraded DNA fragments released into body fluids. Its genetic and pathological information makes it useful for prenatal testing and early tumor detection. However, the mechanisms behind cfDNA biology are largely unknown. In this study, for the first time, we conduct a genome-wide association study (GWAS) to explore the genetic basis of cfDNA end motif frequencies, termed cfGWAS, in 28,016 pregnant women. We identify 15 study-wide significant loci, including the well-known cfDNA-related genes DFFB and DNASE1L3 , as well as novel genes potentially involved in cfDNA biology, such as PANX1 and DNASE1L1 . The findings are further verified through three independent GWAS studies and experimental validation in knockout mice and cell lines. Subsequent analyses reveal strong causal relationships of leukocytes, especially neutrophils, with cfDNA features. In summary, we introduce the cfGWAS, revealing the genetic basis of cfDNA biology on a genome-wide scale. Novel knowledge uncovered by this study promises to revolutionize liquid biopsy technology and lead to potential new drugs targeting certain diseases. Given that millions of cfDNA whole genome sequencing data have been generated from clinical testing, the potential of this paradigm is enormous. Cell-free DNA is widely used in clinical testing, but its genetic basis remains unclear. Here, the authors perform cfGWAS in 28,016 pregnant women, identifying 15 loci linked to cfDNA end motifs and confirming roles for neutrophils through validation studies.

Light quality has significant effects on the growth and metabolite accumulation of algal cells. However, the related mechanism has not been fully elucidated. This study reveals that both red and blue light can promote the growth and biomass accumulation of Chlorella pyrenoidosa, with the enhancing effect of blue light being more pronounced. Cultivation under blue light reduced the content of total carbohydrate in Chlorella pyrenoidosa, while increasing the content of protein and lipid. Conversely, red light decreased the content of protein and increased the content of carbohydrate and lipid. Blue light induces a shift in carbon flux from carbohydrate to protein, while red light transfers carbon flux from protein to lipid. Transcriptomic and metabolomic analysis indicated that both red and blue light positively regulate lipid synthesis in Chlorella pyrenoidosa, but they exhibited distinct impacts on the fatty acid compositions. These findings suggest that manipulating light qualities can modulate carbon metabolic pathways, potentially converting protein into lipid in Chlorella pyrenoidosa.