Hydrogen economy has emerged as a very promising alternative to the current hydrocarbon economy, which involves the process of harvesting renewable energy to split water into hydrogen and oxygen and ...then further utilization of clean hydrogen fuel. The production of hydrogen by water electrolysis is an essential prerequisite of the hydrogen economy with zero carbon emission. Among various water electrolysis technologies, alkaline water splitting has been commercialized for more than 100 years, representing the most mature and economic technology. Here, the historic development of water electrolysis is overviewed, and several critical electrochemical parameters are discussed. After that, advanced nonprecious metal electrocatalysts that emerged recently for negotiating the alkaline oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are discussed, including transition metal oxides, (oxy)hydroxides, chalcogenides, phosphides, and nitrides for the OER, as well as transition metal alloys, chalcogenides, phosphides, and carbides for the HER. In this section, particular attention is paid to the catalyst synthesis, activity and stability challenges, performance improvement, and industry‐relevant developments. Some recent works about scaled‐up catalyst synthesis, novel electrode designs, and alkaline seawater electrolysis are also spotlighted. Finally, an outlook on future challenges and opportunities for alkaline water splitting is offered, and potential future directions are speculated.
The hydrogen economy has emerged as a very promising alternative to the current hydrocarbon economy, which involves the process of harvesting renewable energy to split water into hydrogen and oxygen and then further utilization of hydrogen fuel. Alkaline water splitting represents the most mature and economic technology for clean hydrogen production, making high potential for successful implementation of hydrogen economy.
Facilitating phase conversion efficiency of Li polysulfides to Li2S and restraining the dissolution of Li polysulfides are critical for stable lithium–sulfur (Li–S) batteries. Herein, an in situ ...formed sulfiphilic superfine Fe2O3 nanocrystals confined in lithiophilic N‐doped microporous carbon (Fe2O3/N‐MC) is derived from one‐step hypercrosslinked polymerization. Uniquely, the dual active sites (Fe2O3 and N) in Fe2O3/N‐MC tend to form “FeS, LiO or LiN” bonding, and then synchronically enhancing the chemisorption and interface conversion ability of Li polysulfides. As a result, 80 wt% S is loaded on Fe2O3/N‐MC and the hybrid cathode delivers high mass capacity (730 mA h g‐1) and excellent cycling stability (87.1% capacity retention over 1000 cycles at 5.0 C). Especially, the cathode also exhibits a high reversible areal capacity of 3.69 mA h cm‐2 at a high areal loading (5.1 mg cm‐2) and a lean electrolyte/sulfur (E/S) ratio (7.5 µL mg‐1) over 500 cycles. This work is anticipated to deepen the comprehension of complex Li polysulfides interphase conversion processes and afford new thoughts for designing new host materials.
Facilitating phase conversion efficiency of Li polysulfides to Li2S and restraining the dissolution of Li polysulfides are critical for stable lithium–sulfur (Li–S) batteries. The as‐prepared Fe2O3/N‐microporous carbon (MC) is in favor of enhancing sulfur content, releasing volume expansion, immobilizing soluble lithium polysulfides (LiPSs), and optimizing Li2S nucleation, hence accommodating the S@Fe2O3/N‐MC cathode with excellent cycling stability.
The distribution dependent stochastic differential equations (DDSDEs) describe stochastic systems whose evolution is determined by both the microcosmic site and the macrocosmic distribution of the ...particle. The density function associated with a DDSDE solves a nonlinear PDE. Due to the distribution dependence, some standard techniques developed for SDEs do not apply. By iterating in distributions, a strong solution is constructed using SDEs with control. By proving the uniqueness, the distribution of solutions is identified with a nonlinear semigroup Pt∗ on the space of probability measures. The exponential contraction as well as Harnack inequalities and applications are investigated for the nonlinear semigroup Pt∗ using coupling by change of measures. The main results are illustrated by homogeneous Landau equations.
The construction of C(sp3)‐sulfonyl bonds through direct sulfonylation of C(sp3)−H bond presents a number of challenges, so an electrochemical oxidation‐induced direct sulfonylation of the xanthene ...C(sp3)−H bond was developed. Significant advantages of this method are high atom efficiency, functional group tolerance, transition metal‐ and oxidant‐free conditions. The in vitro cytotoxicity of all product is evaluated by MTT assay against human cancer cell lines. The results reveal that most of the compounds 3 da and 3 af have good inhibitory activity on tumor cell lines.
Most of the resting-state functional magnetic resonance imaging (fMRI) studies demonstrated the correlations between spatially distinct brain areas from the perspective of functional connectivity or ...functional integration. The functional connectivity approaches do not directly provide information of the amplitude of brain activity of each brain region within a network. Alternatively, an index named amplitude of low-frequency fluctuation (ALFF) of the resting-state fMRI signal has been suggested to reflect the intensity of regional spontaneous brain activity. However, it has been indicated that the ALFF is also sensitive to the physiological noise. The current study proposed a fractional ALFF (fALFF) approach, i.e., the ratio of power spectrum of low-frequency (0.01–0.08
Hz) to that of the entire frequency range and this approach was tested in two groups of resting-state fMRI data. The results showed that the brain areas within the default mode network including posterior cingulate cortex, precuneus, medial prefrontal cortex and bilateral inferior parietal lobule had significantly higher fALFF than the other brain areas. This pattern was consistent with previous neuroimaging results. The non-specific signal components in the cistern areas in resting-state fMRI were significantly suppressed, indicating that the fALFF approach improved the sensitivity and specificity in detecting spontaneous brain activities. Its mechanism and sensitivity to abnormal brain activity should be evaluated in the future studies.
The selective oxidation of organic molecules is a fundamentally important component of modern synthetic chemistry. In the past decades, direct oxidative C–H and C–C bond functionalization has proved ...to be one of the most efficient and straightforward methods to synthesize complex products from simple and readily available starting materials. Among these oxidative processes, the use of molecular oxygen as a green and sustainable oxidant has attracted considerable attention because of its highly atom-economical, abundant, and environmentally friendly characteristics. The development of new protocols using molecular oxygen as an ideal oxidant is highly desirable in oxidation chemistry. More importantly, the oxygenation reaction of simple molecules using molecular oxygen as the oxygen source offers one of the most ideal processes for the construction of O-containing compounds. Aerobic oxidation and oxygenation by enzymes, such as monooxygenase, tyrosinase, and dopamine β-monooxygenase, have been observed in some biological C–H bond hydroxylation processes. Encouraged by these biological transformations, transition-metal- or organocatalyst-catalyzed oxygenation through dioxygen activation has attracted academic and industrial prospects. In this Account, we describe some advances from our group in oxygenation via C–H/C–C bond activation with molecular oxygen as the oxidant and oxygen source for the synthesis of O-containing compounds. Under an atmosphere of O2 (1 atm) or air (1 atm), we have successfully incorporated one or two O atoms from O2 into simple and readily available substrates through C–H, C–C, CC, and CC bond cleavage by transition-metal catalysis, organocatalysis, and photocatalysis. Moreover, we have devised cyclization reactions with molecular oxygen to construct O-heterocycles. Most of these transformations can tolerate a broad range of functional groups. Furthermore, on the basis of isotope labeling experiments, electron paramagnetic resonance spectral analysis, and other mechanistic studies, we have demonstrated that a single electron transfer process via a carbon radical, peroxide radical, or hydroxyl radical is involved in these aerobic oxidation and oxygenation reactions. These protocols provide new approaches for the green synthesis of various α-keto amides, α-keto esters, esters, ketones, aldehydes, formamides, 2-oxoacetamidines, 2-(1H)-pyridones, phenols, tertiary α-hydroxy carbonyls, p-quinols, β-azido alcohols, benzyl alcohols, tryptophols, and oxazoles, which have potential applications in the preparation of natural products, bioactive compounds, and functional materials. In most cases, inexpensive and low-toxicity Cu, Fe, Mn, or NHPI was found to be an efficient catalyst for the transformation. The high efficiency, low cost, high oxygen atom economy, broad substrate scope, and practical operation make the developed oxygenation system very attractive and practical. Moreover, the design of new types of molecular-oxygen- or air-based oxidation and oxygenation reactions can be anticipated.
In children with attention deficit hyperactivity disorder (ADHD), functional neuroimaging studies have revealed abnormalities in various brain regions, including prefrontal-striatal circuit, ...cerebellum, and brainstem. In the current study, we used a new marker of functional magnetic resonance imaging (fMRI), amplitude of low-frequency (0.01–0.08
Hz) fluctuation (ALFF) to investigate the baseline brain function of this disorder. Thirteen boys with ADHD (13.0
±
1.4 years) were examined by resting-state fMRI and compared with age-matched controls. As a result, we found that patients with ADHD had decreased ALFF in the right inferior frontal cortex, left sensorimotor cortex, and bilateral cerebellum and the vermis as well as increased ALFF in the right anterior cingulated cortex, left sensorimotor cortex, and bilateral brainstem. This resting-state fMRI study suggests that the changed spontaneous neuronal activity of these regions may be implicated in the underlying pathophysiology in children with ADHD.
A biodegradable two‐dimensional (2D) delivery platform based on loading black phosphorus nanosheets (BPs) with Cas9 ribonucleoprotein engineered with three nuclear localization signals (NLSs) at C ...terminus (Cas9N3) is successfully established. The Cas9N3‐BPs enter cells effectively via membrane penetration and endocytosis pathways, followed by a BPs biodegradation‐associated endosomal escape and cytosolic releases of the loaded Cas9N3 complexes. The Cas9N3‐BPs thus provide efficient genome editing and gene silencing in vitro and in vivo at a relatively low dose as compared with other nanoparticle‐based delivery platforms. This biodegradable 2D delivery platform offers a versatile cytosolic delivery approach for CRISPR/Cas9 ribonucleoprotein and other bioactive macromolecules for biomedical applications.
Cas9 in black: A biodegradable two‐dimensional delivery platform for CRISPR/Cas9 is successfully established. It is based on loading black phosphorus nanosheets with engineered Cas9 ribonucleoprotein, enabling controlled cytosolic release and genome editing with high efficiency.
•Biochar can absorb a large number of essential nutrients for plant growth.•Biochar is an ideal material for reclaiming degraded soils.•Application of biochar on agricultural field is safe.•Concerns ...should be given on some important areas related to biochar utilization.
Excessive land use has a series consequences on the degradation of land function and exerts tremendous pressure on the ecological environment. Farming, mining, and heavy metal pollution have resulted in many negative effects on soils. Biochar has become a hot research topic in the fields of agriculture, environment, and energy as an environmentally friendly soil improver in recent years. The application of biochar for both agricultural and environmental benefits has been studied and reviewed extensively. However, there are limited reviews on the structures of biochar and other biochar applications. This paper provides an overview of recent advances in the effects of the various physicochemical properties of biochar and biochar utilizations including its use as catalyst, soil amendment, water retention, contaminant adsorbent, gas storage, ion exchange, and soil microbial activity. Discussions on biochar on the physical, chemical, biological properties after amendment to the soil and preparation condition. However, the negative effects of biochar in preparations and applications need to be recognized through scientific observation and research. It is anticipated that further research on biochar amendment will increase the understanding on the interactions of biochar with soils, review the negative effects of biochar and it should be alleviated as much as possible.
Glial fibrillary acidic protein (GFAP), a type III intermediate filament, is a marker of mature astrocytes. The expression of GFAP gene is regulated by many transcription factors (TFs), mainly Janus ...kinase‐2/signal transducer and activator of transcription 3 cascade and nuclear factor κ‐light‐chain‐enhancer of activated B cell signaling. GFAP expression is also modulated by protein kinase and other signaling molecules that are elicited by neuronal activity and hormones. Abnormal expression of GFAP proteins occurs in neuroinflammation, neurodegeneration, brain edema‐eliciting diseases, traumatic brain injury, psychiatric disorders and others. GFAP, mainly in α‐isoform, is the major component of cytoskeleton and the scaffold of astrocytes, which is essential for the maintenance of astrocytic structure and shape. GFAP also has highly morphological plasticity because of its quick changes in assembling and polymerizing states in response to environmental challenges. This plasticity and its corresponding cellular morphological changes endow astrocytes the functions of physical barrier between adjacent neurons and stabilizer of extracellular environment. Moreover, GFAP colocalizes and even molecularly associates with many functional molecules. This feature allows GFAP to function as a platform for direct interactions between different molecules. Last, GFAP involves transportation and localization of other functional proteins and thus serves as a protein transport guide in astrocytes. This guiding role of GFAP involves an elastic retraction and extension cytoskeletal network that couples with GFAP reassembling, transporting, and membrane protein recycling machinery. This paper reviews our current understanding of the expression and functions of GFAP as well as their regulation.
Main points
GFAP expression is regulated by transcription factors and enzymes at multiple levels;
GFAP serves as cytoskeleton, interactive platform, and protein location guide;
The guiding role of GFAP involves cellular transport and mobile machineries.
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