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Not AvailableAn unmet challenge in radical relay difunctionalization of alkenes is incorporation of two discrete transient radicals in a regiocontrolled manner under transition metal-free conditions. Current protocols typically rely on persistent radicals or organometallic surrogates to trap radical adducts, thereby suppressing the undesired reactions but limiting the diversity. The direct use of two transient radicals remains synthetically elusive. We present a visible-light photoredox catalyzed alkene dialkylation strategy via a kinetically guided conjugative radical-radical coupling. This transition-metal-free approach enables two direct C(sp3)−C(sp3) bond formations across the C=C double bond using alkyl and allyl or benzyl radicals. Mechanistic investigations reveal the radical nature of the process. The success of this approach hinges on kinetically controlled radical addition to alkene substrates and the steric protection of the resulting radical adducts. This mild and functional-group tolerant reaction exhibits broad substrate scope and tolerates structurally complex substrates, highlighting its potential for late-stage functionalization. 

The popularity of smart home devices has led to an increase in security incidents happening in smart homes. A key measure to avoid such incidents is to authenticate users before they can interact with smart devices. However, current methods often require additional hardware. This article proposes STATION, a gesture-based authentication system, an effective gesture-based authentication method built on top of the voice interfaces already available in these smart home devices, without adding new hardware. STATION uses a gesture processing pipeline that identifies Doppler-existing frames and detects the direction of arrival of Reflection to authenticate users in low SNR environments and at longer distances. Furthermore, regarding the nature of gesture-based authentication, this system also supports detecting user liveness, preventing replay and synthesis attacks from remote attackers. The evaluation of STATION shows high accuracy with a false acceptance rate (FAR) of 0.08% and false rejection rate (FRR) of 3.10% for users within 1.5 m of the device. 

Lactones are cyclic esters with extensive applications in materials science, medicinal chemistry, and the food and perfume industries. Nature’s strategy for the synthesis of many lactones found in natural products always relies on a single type of retrosynthetic strategy, a C−O bond disconnection. Here, we describe a set of laboratory-engineered enzymes that use a new-tonature C−C bond-forming strategy to assemble diverse lactone structures. These engineered “carbene transferases” catalyze intramolecular carbene insertions into benzylic or allylic C−H bonds, which allow for the synthesis of lactones with different ring sizes and ring scaffolds from simple starting materials. Starting from a serine-ligated cytochrome P450 variant previously engineered for other carbene-transfer activities, directed evolution generated a variant P411-LAS-5247, which exhibits a high activity for constructing a five-membered ε-lactone, lactam, and cyclic ketone products (up to 5600 total turnovers (TTN) and >99% enantiomeric excess (ee)). Further engineering led to variants P411-LAS-5249 and P411-LAS-5264, which deliver six-membered δ-lactones and seven-membered ε-lactones, respectively, overcoming the thermodynamically unfavorable ring strain associated with these products compared to the γ-lactones. This new carbene-transfer activity was further extended to the synthesis of complex lactone scaffolds based on fused, bridged, and spiro rings. The enzymatic platform developed here complements natural biosynthetic strategies for lactone assembly and expands the structural diversity of lactones accessible through C−H functionalization. 

Abstract Measuring one-point statistics in redshifted 21 cm intensity maps offers an opportunity to explore non-Gaussian features of the early Universe. We assess the impact of instrumental effects on measurements made with the Hydrogen Epoch of Reionization Array (HERA) by forward modeling observational and simulation data. Using HERA Phase I observations over 94 nights, we examine the second (m₂, variance) and third (m₃) moments of images. We employ theDAYENU-filtering method for foreground removal and reduce simulated foreground residuals to 10% of the 21 cm signal residuals. In noiseless cosmological simulations, the amplitudes of one-point statistics measurements are significantly reduced by the instrument response and further reduced by wedge-filtering. Analyses with wedge-filtered observational data, along with expected noise simulations, show that systematics alter the probability distribution of the map pixels. A likelihood analysis based on the observational data showsm₂measurements disfavor the cold reionization model characterized by inefficient X-ray heating, in line with other power spectra measurements. Small signals inm₃due to the instrument response of the Phase I observation and wedge-filtering make it challenging to use these non-Gaussian statistics to explore model parameters. Forecasts with the full HERA array predict high signal-to-noise ratios form₂,m₃, andS₃assuming no foregrounds, but wedge-filtering drastically reduces these ratios. This work demonstrates conclusively that a comprehensive understanding of instrumental effects onm₂andm₃is essential for their use as a cosmological probe, given their dependence on the underlying model.