Cell Reports Physical Science最新文献

As a critical element of the technological infrastructure of body sensor networks (BSNs), wearable electromagnetic vibration energy harvesters (EMVEHs) are a competitive candidate for breaking through the development bottleneck of BSNs’ sustainability, and thus facilitating their self-sustained operations with versatile functions. To this end, the prior concern of wearable EMVEHs is to enhance their adaptability to complex biomechanics of human motions for better power generation performance. Given the state-of-the-art progress of this BSN enabling technology, we provide a comprehensive and in-depth summary of recent excitation-adaptive designs of miniaturized wearable EMVEHs focusing on their insightful vibration pick-up structures here, to systematically clarify a developing roadmap of this branch of science and then offer inspirations for the underway endeavors focused on energy harvesting from human motions. In this way, we try to lift the impacts of current innovative efforts in this field and corresponding BSN achievements to a higher level.

Aryl trifluoromethyl ethers (ArOCF₃) are important structural motifs in pharmaceuticals, agrochemicals, and functional materials. However, the methods reported for the efficient synthesis of these scaffolds are extremely underdeveloped and limited. Here, we report a highly efficient mechanochemical approach for the selective transformation of aryltrimethylammonium triflates, aryldiazonium tetrafluoroborates, and aryl pinacolboranes to aryl trifluoromethyl ethers via in situ-generated OCF₃ source using triphosgene and Co(II) fluoride (CoF₂). The proposed synthetic protocol also shows potential for the selective transformation of other groups such as arylsulfonium and diaryliodonium functionalities. The present trifluoromethoxylation strategy exhibited a broad functional group tolerance and found to be superior over other existing protocols in terms of substrate scope, yields, operational simplicity, and reaction times.

To break through the Shockley-Queisser limit of single-junction photovoltaics, monolithic two-terminal (2T) perovskite/silicon tandem solar cells (TSCs) have shown promise in recent years. Self-assembled monolayers (SAMs) as interconnecting layers (ICLs) for efficient perovskite/silicon TSCs are favorable due to their negligible optical and electrical loss. However, the inhomogeneity of SAMs results in defects at the interface between SAMs and transparent conductive oxide (TCO). To solve this issue, in this work, we employ the sputtered nickel oxide (NiO_x) as the seed layer of MeO-2PACz SAMs to build hybrid ICLs in perovskite/silicon TSCs. It is found that the hybrid ICLs of NiO_x/MeO-2PACz significantly reduce current leakage and non-radiative recombination losses by avoiding direct contact between perovskites and TCO. As a result, we can fabricate reproducible and stable monolithic 2T perovskite/silicon TSCs with an efficiency of 28.47% and an impressive fill factor of 81.8%.

Explaining black box predictions of machine learning (ML) models is a topical issue in artificial intelligence (AI) research. For the identification of features determining predictions, the Shapley value formalism originally developed in game theory is widely used in different fields. Typically, Shapley values quantifying feature contributions to predictions need to be approximated in machine learning. We introduce a framework for the calculation of exact Shapley values for 4 kernel functions used in support vector machine (SVM) models and analyze consistently accurate compound activity predictions based on exact Shapley values. Dramatic changes in feature contributions are detected depending on the kernel function, leading to mostly distinct explanations of predictions of the same test compounds. Very different feature contributions yield comparable predictions, which complicate numerical and graphical model explanation and decouple feature attribution and human interpretability.

Flexible wearable devices require conductive hydrogels that can withstand extreme conditions. Yet, most strategies for improving environmental tolerance compromise other properties, including mechanical modulus and electromagnetic interference (EMI) shielding. Herein, we design polyvinyl alcohol/polypyrrole double-network organohydrogels with tunable EMI shielding and mechanical properties by introducing specific ions and glycerol. The synergistic effect of high-concentration “salting-in” ions and glycerol/water systems enables 3 M AlCl₃-treated organohydrogels to exhibit exceptional environmental tolerance. These gels display excellent shielding performance above 40 dB and enhanced modulus-like human skin. Glycerol restores the mechanical properties deteriorated by “salting-in” ions, and AlCl₃ promotes ion migration to improve EMI shielding. Additionally, these organohydrogels can also serve as strain sensors, monitoring human motions and maintaining stable shielding (>25 dB) even after subzero treatment or long-term use. Overall, this work offers a generalizable strategy for fabricating multifunctional organohydrogels, paving the way for advancements in gel-based flexible wearable devices.

Sequential reactions are important for the direct and convenient synthesis of complex molecules with multiple chiral centers. Here, we report an enantioselective sequential Michael addition/C–H olefination/Michael addition reaction for the asymmetric construction of chiral 2-aminotetralin derivatives bearing three stereogenic centers using readily accessible 2-aryl N-quinolyl acrylamide, nitromethane, and alkenyl iodide. This optimized process utilizes a quinine-based squaramide bifunctional organocatalyst in the enantioselective Michael addition of nitromethane to a conjugated amide. Subsequently, the N,N-bidentate amide-directed Pd-catalyzed C–H olefination of the 2-arylamide and intramolecular Michael addition of a conjugated ester generates tetralins with high enantioselectivities and good stereoselectivities and yields. To demonstrate the synthetic utility of this sequential reaction, the collective synthesis of various clavine alkaloids with different skeletons is accomplished from a common tricyclic intermediate that can be readily prepared using chiral 2-aminotetralins.

Stereolithography-based three-dimensional (3D) printing technology is widely employed in various industries, including manufacturing, healthcare, energy, biomedical, art, and other fields. However, precision issues, such as dimensional shrinkage and structural warping, significantly hinder its wide application. In this study, we present a straightforward and efficient yet general strategy to enhance structural fidelity by incorporating thermally expandable microspheres into photosensitive resins. We found that this reduction substantially mitigates the volume shrinkage below 3.98% compared to over 10% for commercial photosensitive resins. Precision improves significantly, with dimensional deviation at just 0.035% compared to over 0.1% with commercial options. Furthermore, due to the low filling ratio, the improvement in 3D printing precision did not affect the mechanical properties; thus, it does not affect applications where those photosensitive resins are originally targeted. Our method represents an effective strategy to improve the 3D printing resolution of photosensitive resins, thus opening directions for high-precision 3D printing technology.

While oxidative cleavage has been a well-known strategy to degrade unsaturated polymers, most processes require harsh conditions and/or expensive oxidizing agents. Using O₂ to degrade polymers is highly desirable, but no reported process is well controlled for the chemical recycling of polymers. Here, we report a photo-mediated oxidative degradation process for unsaturated polymers under O₂ using an earth-abundant Mn catalyst, and the process is demonstrated with polybutadiene, polydicyclopentadiene, and dehydrogenated polyethylene. Nonactivated internal alkenes in these polymers can be effectively cleaved without elevated temperature or pressure. The oxidation process generates acetal as the main functionality, which can be used for further recycling. As a proof of concept, the oligomers with acetal end groups, resulting from the oxidation of polybutadiene, are shown to undergo transacetalization with polyols to form a polymer network. The oxidation process demonstrated here holds promise for the recycling of hydrocarbon polymers under mild conditions in a cost-effective fashion.

Amines, hydrazines, and nitrogen-containing heterocycles are pivotal species in medicine, agriculture, fine chemicals, and materials. Diazirines have been recently reported to serve as versatile electrophilic amination reagents for the synthesis of building blocks or late-stage C–N bond formation. Here, we report the catalytic photodecarboxylative amination of carboxylic acids with diazirines under mild conditions. The substrate scope includes broad functional group tolerance, such as ketones, esters, olefins, and alcohols, along with the late-stage amination of naproxen, ibuprofen, gemfibrozil, and gibberellic acid. Synthetic applications leverage the versatility of the intermediate diaziridines and include the regioselective preparation of a suite of 1H-indazoles, 2H-indazoles, and fluoroquinolones.