A novel method by a one-step introduction of axial chirality and sterically hindered group has been developed for facile synthesis of axially chiral styrene-type carboxylic acids. With the ...palladium-catalyzed C–H arylation and olefination of readily available cinnamic acid established, this transformation demonstrated excellent yield, excellent stereocontrol (up to 99% yield and 99% ee), and broad substrate scope under mild conditions. The axially chiral styrene-type carboxylic acids produced have been successfully applied to Cp*Co III -catalyzed asymmetric C–H activation reactions, indicating their potential as chiral ligands or catalysts in asymmetric synthesis.
Enantioselective synthesis of tetrahydroisoquinolines bearing an all-carbon quaternary stereogenic center, was achieved
via
asymmetric C-H activation with high enantioselectivities (up to 93% ee). ...Fair substrate tolerance was indicated throughout the scope investigation and no evident loss of enantioselectivity was exhibited in late-stage derivatization. This study provides incentives for the construction of diverse chiral isoquinoline derivatives, which are prevalent among pharmaceuticals, natural products,
etc.
Enantioselective synthesis of isoquinoline derivatives bearing an all-carbon quaternary stereocenter in one step
via
asymmetric Pd(
ii
)-catalyzed C-H activation and multiple late-stage derivatizations.
With the rapidly aging society and increased concern for personal cardiovascular health, novel, flexible electrodes suitable for electrocardiogram (ECG) signal monitoring are in demand. Based on the ...excellent electrical and mechanical properties of graphene and the rapid development of graphene device fabrication technologies, graphene-based ECG electrodes have recently attracted much attention, and many flexible graphene electrodes with excellent performance have been developed. To understand the current research progress of graphene-based ECG electrodes and help researchers clarify current development conditions and directions, we systematically review the recent advances in graphene-based flexible ECG electrodes. Graphene electrodes are classified as bionic, fabric-based, biodegradable, laser-induced/scribed, modified-graphene, sponge-like, invasive, etc., based on their design concept, structural characteristics, preparation methods, and material properties. Moreover, some categories are further divided into dry or wet electrodes. Then, their performance, including electrode–skin impedance, signal-to-noise ratio, skin compatibility, and stability, is analyzed. Finally, we discuss possible development directions of graphene ECG electrodes and share our views.
With its excellent electrical and mechanical properties and the rapid development of its device fabrication technologies, laser-induced graphene (LIG) has played an important role in the field of ...wearable technologies since its discovery in 2014. In recent years, with the relentless development of wearable devices, newly developed LIG-based wearable devices also possess multifunction and intelligence characteristics. This review is aimed toward two of the most important fields related to the development of LIG, namely, health care and human–computer interaction (HCI). We introduce multifunctional and intelligent LIG-based wearable systems for health care and HCI developed over the recent years, sorting out their design ideas, preparation process, performance, and application. Furthermore, we discuss the future development direction of LIG-based wearable systems for health care and HCI.
Since the Anthropocene, biodiversity loss owing to human activity and climate change has worsened. Quercus gilva is an evergreen oak species native to China, Japan, and South Korea and is threatened ...by a long history of human impact. The purpose of this study was to (1) reassess the threatened category of Q. gilva based on a detailed survey, and (2) identify the genetic structure and diversity of Q. gilva based on genomic data. First, we conducted a detailed survey of the populations in China. Second, we collated all the literature and information. Finally, genome-wide genetic variation was analyzed based on 65 individuals from 22 populations. We found that Q. gilva has suffered rapid population decline, and at present, most populations are very small. The evolutionary path of Q. gilva was from the southwest to east of China and then to Japan and South Korea. Quercus gilva showed no distinct genetic structure and had a relatively low genetic diversity. Among the 22 populations, most populations in southwestern China, South Korea, and Japan had high genetic diversity. The populations in Jingning (Zhejiang province; ZJN), Wuyuan (Jinaxi province; JWY), and Zherong (Fujian province; FZR) suffered a strong bottleneck. In conclusion, Q. gilva is an endangered species native to East Asia. Because of the very low genetic diversity of Q. gilva and most populations are small, we need to (1) strengthen the protection of this species, (2) conduct conservation actions with in-situ reinforcement populations, and (3) select populations with high genetic diversity as provenances for afforestation efforts. Finally, we suggest that in the future, genetic diversity should be considered as the sixth criterion for IUCN to evaluate the threatened category.
As an alternative approach to traditional C–H activation that often involved harsh conditions, and vicinal or primary C–H functionalization, radical relay offers a solution to these long-held ...problems. Enabled by 1, n ( n = 5, 6)-hydrogen atom transfer (HAT), we use a most prevalent moiety, alkene, as the precursor to an sp 3 C-centered radical to promote selective cleavage of inert C(sp 3 )–H bonds for the generation of azidotrifluoromethylated molecules. Mild conditions, broad scope and excellent regioselective control (>20 : 1) are observed in the reactions. Deuterium labelling studies disclose the kinetic characteristics of the transformations and verify a direct 1, n -HAT pathway. The key to this C-centered radical relay is that iron plays a dual role as a radical initiator and terminator to incorporate the azide functionality through radical oxidation via azido–ligand-transfer. The methods and the later derivatization promise expeditious synthesis of CF 3 -containing organic azides, γ-lactam and triazoles that are widely used in designing new fluorescent tags and functional materials.
Nearly half of pregnancies worldwide are unintended mainly due to failure of contraception, resulting in negative effects on women’s health. Male contraception techniques, primarily condoms and ...vasectomy, play a crucial role in birth control, but cannot be both highly effective and reversible at the same time. Herein, an ultrasound (US)-induced self-clearance hydrogel capable of real-time monitoring is utilized for in situ injection into the vas deferens, enabling effective contraception and noninvasive recanalization whenever needed. The hydrogel is composed of (i) sodium alginate (SA) conjugated with reactive oxygen species (ROS)-cleavable thioketal (SA-tK), (ii) titanium dioxide (TiO2), which can generate a specific level of ROS after US treatment, and (iii) calcium chloride (CaCl2), which triggers the formation of the hydrogel. For contraception, the above mixture agents are one-time injected into the vas deferens, which can transform from liquid to hydrogel within 160 s, thereby significantly physically blocking the vas deferens and inhibiting movability of sperm. When fertility is needed, a noninvasive remedial ultrasound can make TiO2 generate ROS, which cleaves SA-tK to destroy the network of the hydrogel. Owing to the recanalization, the refertility rate is restored to 100%. Meanwhile, diagnostic ultrasound (D-US, 22 MHz) can monitor the occlusion and recanalization process in real-time. In summary, the proposed hydrogel contraception can be a reliable, safe, and reversible male contraceptive strategy that addresses an unmet need for men to control their fertility.
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•A self-powered triboelectric catalyst is prepared by electrostatic spinning.•The triboelectric catalysts promote the generation of reactive oxygen species.•Triboelectric charges ...promote the continuous decomposition of intermediate products.•The CO2 production efficiency can be improved to78.93%.
The accumulation of intermediates is an important reason for the inactivation of many catalysts including formaldehyde (HCHO) degradation materials. Herein, self-powered triboelectric catalysts (MnOx-PMMA-SSM) with a three-dimensional nanocomposite structure self-assembled by nanoflowered MnOx inlaid porous polymethyl methacrylate (PMMA) nanofibers based on stainless steel mesh (SSM) substrate, is fabricated by electrostatic spinning and hydrolysis methods. The self-powered triboelectric catalysts can promote the generation of reactive oxygen species (O*) under the action of triboelectric charges from the friction between PMMA fibers and SSM driven by the wind, thus promoting the catalytic oxidation of HCHO and intermediates. In the 15 ppm HCHO atmosphere, the CO2 production efficiency for the self-powered triboelectric catalysts can improve 36.25% up to78.93% compared with traditional MnOx catalysts, and the catalyst life is as high as 72 h without evident decay. This research provides a new strategy for high-efficiency, long-term and zero-energy degradation HCHO at room temperature.
Defensive behavior, a group of responses that evolved due to threatening stimuli, is crucial for animal survival in the natural environment. For defensive measures to be timely and successful, a high ...arousal state and immediate sleep-to-wakefulness transition are required. Recently, the glutamatergic basal forebrain (BF) has been implicated in sleep-wake regulation; however, the associated physiological functions and underlying neural circuits remain unknown. Here, using in vivo fiber photometry, we found that BF glutamatergic neuron is activated by various threatening stimuli, including predator odor, looming threat, sound, and tail suspension. Optogenetic activation of BF glutamatergic neurons induced a series of context-dependent defensive behaviors in mice, including escape, fleeing, avoidance, and hiding. Similar to the effects of activated BF glutamatergic cell body, photoactivation of BF glutamatergic terminals in the ventral tegmental area (VTA) strongly drove defensive behaviors in mice. Using synchronous electroencephalogram (EEG)/electromyogram (EMG) recording, we showed that photoactivation of the glutamatergic BF-VTA pathway produced an immediate transition from sleep to wakefulness and significantly increased wakefulness. Collectively, our results clearly demonstrated that the glutamatergic BF is a key neural substrate involved in wakefulness and defensive behaviors, and encodes these behaviors through glutamatergic BF-VTA pathway. Overexcitation of the glutamatergic BF-VTA pathway may be implicated in clinical psychiatric diseases characterized by exaggerated defensive responses, such as autism spectrum disorders.
•Glutamatergic neurons in the BF responses to various threatening stimuli.•Optogenetic activation of BF glutamatergic neurons triggers a range of context-dependent defensive behaviors.•Activation of BF glutamatergic terminals in the VTA also strongly promotes defensive behavior.•Photoactivating glutamatergic BF-VTA pathway induces transition to wakefulness and increases amount of wakefulness.
In northern China, the strategy used for central heating of buildings in winter is usually climate compensator, but this strategy relies heavily on manual experience, and the adjustment is relatively ...extensive. How to optimize the heating control strategy is very important to maintain the stable and comfortable room temperature of the building. This paper proposes a A heating strategy optimization method based on deep learning, which optimizes the original control strategy by learning historical real data information. Firstly, with the goal of learning the thermodynamic laws of indoor temperature changes, a deep multi-time differential network (MTDN) is proposed. Difference Network) to predict the room temperature at the next moment, the network not only has high accuracy, but also conforms to the laws of physics; then MTDN is used as a simulator, and the evaluation index representing the thermal response of the human body is used as the relevant reward item. The SAC (Soft Actor Critic) algorithm of the learn
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