Herein, we report a novel cobalt-catalyzed stereodivergent transfer hydrogenation of alkynes to Z- and E-alkenes. Effective selectivity control is achieved based on a rational catalyst design. ...Moreover, this mild system allows for the transfer hydrogenation of alkynes bearing a wide range of functional groups in good yields using catalyst loadings as low as 0.2 mol %. The general applicability of this procedure is highlighted by the synthesis of more than 50 alkenes with good chemo- and stereoselectivity. A preliminary mechanistic study revealed that E-alkene product was generated via sequential alkyne hydrogenation to give Z-alkene intermediate, followed by a Z to E alkene isomerization process.
Although molecular regulation of cellulolytic enzyme production in filamentous fungi has been actively explored, the underlying signaling processes in fungal cells are still not clearly understood. ...In this study, the molecular signaling mechanism regulating cellulase production in
was investigated. We found that the transcription and extracellular cellulolytic activity of four cellulolytic enzymes (
,
,
, and
) increased in Avicel (microcrystalline cellulose) medium. Intracellular nitric oxide (NO) and reactive oxygen species (ROS) detected by fluorescent dyes were observed in larger areas of fungal hyphae grown in Avicel medium compared to those grown in glucose medium. The transcription of the four cellulolytic enzyme genes in fungal hyphae grown in Avicel medium was significantly decreased and increased after NO was intracellularly removed and extracellularly added, respectively. Furthermore, we found that the cyclic AMP (cAMP) level in fungal cells was significantly decreased after intracellular NO removal, and the addition of cAMP could enhance cellulolytic enzyme activity. Taken together, our data suggest that the increase in intracellular NO in response to cellulose in media may have promoted the transcription of cellulolytic enzymes and participated in the elevation of intracellular cAMP, eventually leading to improved extracellular cellulolytic enzyme activity.
Conjugated polymers that can efficiently transport both ionic and electronic charges have broad applications in next‐generation optoelectronic, bioelectronic, and energy storage devices. To date, ...almost all the conjugated polymers have hydrophobic backbones, which impedes efficient ion diffusion/transport in aqueous media. Here, we design and synthesize a novel hydrophilic polymer building block, 4a‐azonia‐naphthalene (AN), drawing inspiration from biological systems. Because of the strong electron‐withdrawing ability of AN, the AN‐based polymers show typical n‐type charge transport behaviors. We find that cationic aromatics exhibit strong cation‐π interactions, leading to smaller π–π stacking distance, interesting ion diffusion behavior, and good morphology stability. Additionally, AN enhances the hydrophilicity and ionic‐electronic coupling of the polymer, which can help to improve ion diffusion/injection speed, and operational stability of organic electrochemical transistors (OECTs). The integration of cationic building blocks will undoubtedly enrich the material library for high‐performance n‐type conjugated polymers.
We develop a novel hydrophobic building block, 4a‐azonia‐naphthalene (AN), for n‐type organic mixed ionic‐electronic conductors. AN have the strong electron‐withdrawing ability, and exhibit strong cation‐π interactions, leading to smaller π–π stacking distance, interesting ion diffusion behavior, and good morphology stability, resulting in improved ion diffusion/injection speed and operational stability of organic electrochemical transistors.
Carbon dots (CDs) are photoluminescent nanomaterials with wide-ranging applications. Despite their photoactivity, it remains unknown whether CDs degrade under illumination and whether such ...photodegradation poses any cytotoxic effects. Here, we show laboratory-synthesized CDs irradiated with light degrade into molecules that are toxic to both normal (HEK-293) and cancerous (HeLa and HepG2) human cells. Eight days of irradiation photolyzes 28.6-59.8% of the CDs to <3 kilo Dalton molecules, 1431 of which are detected by high-throughput, non-target high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry. Molecular network and community analysis further reveal 499 cytotoxicity-related molecules, 212 of which contain polyethylene glycol, glucose, or benzene-related structures. Photo-induced production of hydroxyl and alkyl radicals play important roles in CD degradation as affected by temperature, pH, light intensity and wavelength. Commercial CDs show similar photodegraded products and cytotoxicity profiles, demonstrating that photodegradation-induced cytotoxicity is likely common to CDs regardless of their chemical composition. Our results highlight the importance of light in cytocompatibility studies of CDs.
Plants need to cope with multitudes of stimuli throughout their lifecycles in their complex environments. Calcium acts as a ubiquitous secondary messenger in response to numerous stresses and ...developmental processes in plants. The major Ca
sensors, calcineurin B-like proteins (CBLs), interact with CBL-interacting protein kinases (CIPKs) to form a CBL-CIPK signaling network, which functions as a key component in the regulation of multiple stimuli or signals in plants. In this review, we describe the conserved structure of CBLs and CIPKs, characterize the features of classification and localization, draw conclusions about the currently known mechanisms, with a focus on novel findings in response to multiple stresses, and summarize the physiological functions of the CBL-CIPK network. Moreover, based on the gradually clarified mechanisms of the CBL-CIPK complex, we discuss the present limitations and potential prospects for future research. These aspects may provide a deeper understanding and functional characterization of the CBL-CIPK pathway and other signaling pathways under different stresses, which could promote crop yield improvement via biotechnological intervention.
In this paper, an MMV-SWACGP algorithm is proposed, in order to solve the problem of pseudo-inverse computation in the iterative process of OMPMMV algorithm for multi-band signal reconstruction by ...compressed sensing. This algorithm reduces the complexity and computation of OMPMMV reconstruction algorithm. It is of great significance to the fast reconstruction of sparse multiband signals. Theoretical analysis and simulation results show that the proposed algorithm has faster computation speed and better noise stability.
In the current study, the solidification structure, non-metallic inclusions and hot ductility of continuously cast high manganese TWIP steel slab have been investigated and the inclusion formation ...behavior have been revealed by FactSage (CRCT-ThermFact Inc., Montréal, Canada). The area ratio of equiaxed grain zone of the TWIP steel slab is 0.18. Two main types of inclusions in the TWIP steel slab are single AlN particle and AlN+MnS aggregates. It is found that MgAl2O4 and AlN particles can precipitate in the initial solidification stage, which can act as heterogeneous nuclei of other inclusions. In the high temperature tension test, the reduction of area (RA) of the TWIP steel slab samples are higher than 40 pct in the temperature range from 873 K to 1473 K (600°C to 1200°C). Brittle fractures are observed in the fracture surface of the TWIP steel slab samples with dimples. Contents of manganese, carbon, sulfur and phosphorus, strain rate, and dynamic recrystallization (DRX) are factors influencing the hot ductility of TWIP steel slab.
In recent years, non-thermal plasma (NTP) technology has been extensively applied in medical, environmental, biological, and agricultural fields. The sunflower (
Helianthus annus
L.) is valued by ...farmers as a relatively common, economically valuable agricultural crop. In this study, our purpose was to use NTP technology to identify suitable conditions to promote sunflower seed germination and seedling growth, and to elucidate the mechanism of action. Our research found that 16.8 kV treatment for 15 s had the greatest effect on seed germination and growth in Chinese sunflower seeds. Interestingly, American sunflower seeds were not sensitive to this treatment. NTP treatment increased the concentration of solubilized protein, antioxidant enzyme activity and expression, and adenosine triphosphate (ATP) production. It also upregulated
ATPa2, ATPb1–3,
the target of rapamycin (
TOR
)
,
and growth-regulating factors (
GRF
) 1–3 and 6, while it downregulated
ATPMI25
mRNA expression in 14-day-old sunflower leaves. These results indicate that argon NTP promoted sunflower seed germination and growth by regulating superoxide dismutase 2 (SOD2), catalase (CAT),
ATP
,
TOR
, and
GRFs
. Transcriptome analysis showed that various key genes are involved in starch and sucrose metabolism, pentose and glucoronate interconversions, DNA replication, and plant hormone signal transduction. Our analysis provides comprehensive gene expression information at the transcriptional level, which lays the foundation for further analysis of the function of candidate genes required for the development and growth of sunflower, and contributes to the understanding of the molecular mechanism of sunflower growth.
We analyze possible effects of the dark matter environment on the atomic clock stability measurements. The dark matter is assumed to exist in the form of waves of ultralight scalar fields or in the ...form of topological defects (monopoles and strings). We identify dark matter signal signatures in clock Allan deviation plots that can be used to constrain the dark matter coupling to the Standard Model fields. The existing data on the Al+/Hg+ clock comparison are used to put new limits on the dilaton dark matter in the region of masses mφ>10−15 eV. We also estimate the sensitivities of future atomic clock experiments in space, including the cesium microwave and strontium optical clocks aboard the International Space Station, as well as a potential nuclear clock. These experiments are expected to put new limits on the topological dark matter in the range of masses 10−10 eV<mφ<10−6 eV.
Growing microbial resistance to existing drugs and the search for new natural products of pharmaceutical importance have forced researchers to investigate unexplored environments, such as extreme ...ecosystems. The deep-sea (>1000 m below water surface) has a variety of extreme environments, such as deep-sea sediments, hydrothermal vents, and deep-sea cold region, which are considered to be new arsenals of natural products. Organisms living in the extreme environments of the deep-sea encounter harsh conditions, such as high salinity, extreme pH, absence of sun light, low temperature and oxygen, high hydrostatic pressure, and low availability of growth nutrients. The production of secondary metabolites is one of the strategies these organisms use to survive in such harsh conditions. Fungi growing in such extreme environments produce unique secondary metabolites for defense and communication, some of which also have clinical significance. Despite being the producer of many important bioactive molecules, deep-sea fungi have not been explored thoroughly. Here, we made a brief review of the structure, biological activity, and distribution of secondary metabolites produced by deep-sea fungi in the last five years.
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