One of the main issues in designing optimum tapered cascades for uranium enrichment for annual fuel production in a power reactor is whether to employ large(fat)or small(thin)cascades.What will be the permissible and ...One of the main issues in designing optimum tapered cascades for uranium enrichment for annual fuel production in a power reactor is whether to employ large(fat)or small(thin)cascades.What will be the permissible and optimal ranges of the number of machines that can be used in a cascade?For the first time,the permissible and optimal ranges of the number of gas centrifuges that can be utilized in a cascade were investigated using two types of centrifuges,and the performance of small and large tapered cascades was discussed.The particle swarm optimization algorithm(PSO)has been used to optimize tapered cascades.The results show:(1)For the first centrifuge,41 cascades(91≤n≤4897)and for the second centrifuge,49 cascades(18≤n≤3839)with small and large sizes can be used in enrichment facilities,and the best cascade for them has 530(with 23 stages)and 39(with 7 stages)centrifuges,respectively.(2)For both centrifuges,when 600≤n(number of centrifuges=n),the large cascade performance changes are relatively insignificant.(3)For both types of gas centrifuges,the annual los s of separation power in enrichment facilities is approximately 1.25%-4.82%of the total separation work required.展开更多
Photo-responsive supramolecular assembly especially supramolecular hydrogels with tunable luminescence show a promising application potential in writable information recording and display materials.Herein,we report ph...Photo-responsive supramolecular assembly especially supramolecular hydrogels with tunable luminescence show a promising application potential in writable information recording and display materials.Herein,we report photo-responsive reversible multicolor supramolecular hydrogel with near-infrared emission,which is constructed by cucurbit[7]uril(CB[7]),cyanostilbene derivative(DAC)and Laponite XLG(LP)via supramolecular cascade assembly.Compared with the free vip molecule DAC,the confinement of macrocycle CB[7]achieve effective near-infrared fluorescence in the aqueous phase from scratch,and the subsequent cascade assembly with LP further restrict the molecular rotation of the DAC,which not only result in a substantial enhancement of the fluorescence intensity,but is also endowed with light-controlled fluorescence on/off both in the solution and hydrogel states.Further,8-hydroxy-1,3,6-pyrenetrisulfonic acid trisodium salt(HPTS)is introduced in the cascade assembly to fabricated photocontrollable reversible multicolor luminescence supramolecular hydrogel between red and green induced by Förster resonance energy transfer,which is successfully employed in reversible multiple information encryption.展开更多
A visible-light induced cascade sulfonation/cyclization reaction of 3-allyl-2-arylquinazolinones employing water as an environmentally friendly solvent was revealed.This transition metal-free protocol,using 9-mesityl-...A visible-light induced cascade sulfonation/cyclization reaction of 3-allyl-2-arylquinazolinones employing water as an environmentally friendly solvent was revealed.This transition metal-free protocol,using 9-mesityl-10-methylacridinium perchlorate as the photocatalyst,represents a masterly tactic for the synthesis of sulfonated dihydroisoquinolino[1,2-b]quinazolinones featuring mild conditions,facile operation,and broad substrate scope.展开更多
The evolutionarily conserved mitogen-activated protein kinase(MAPK)cascades relay extracellular signals into cells,triggering a variety of cellular responses.We previously revealed NtMPK4 as a positive regulator of ni...The evolutionarily conserved mitogen-activated protein kinase(MAPK)cascades relay extracellular signals into cells,triggering a variety of cellular responses.We previously revealed NtMPK4 as a positive regulator of nicotine biosynthesis;however,its upstream regulation remains unclear.Here,we characterized a MAPK cascade,comprising NtMEKK1b,NtMPKK2a,and NtMPK4,that promotes nicotine biosynthesis.This signaling module transduces external cues,including jasmonate and pathogen elicitors such as flg22,into post-translational modifications that enhance transcriptional activity and pathway gene expression.NtMPKK2a physically interacts with and phosphorylates NtMPK4 in vivo,confirming its role as an upstream kinase.RNAi-mediated silencing of NtMPKK2a significantly reduced the expression of nicotine pathway genes and decreased nicotine accumulation,whereas induced-overexpression of NtMPKK2a upregulated nicotine pathway genes and increased nicotine contents in tobacco hairy roots.Overexpression of NtMPKK2a in tobacco cells enhanced the transactivation activity of a NIC2-locus Ethylene Response Factor NtERF221 on Putrescine N-methyltransferase(NtPMT)promotor,further supporting its role in promoting nicotine biosynthesis.Furthermore,we identified NtMEKK1b,a tobacco MEKK that interacts with NtMAPKK2a in yeast cells.Knock-down of NtMEKK1b in transgenic tobacco plants attenuated the expression of nicotine pathway genes and reduced nicotine contents,whereas induced-overexpression of NtMEKK1b upregulated gene expression and nicotine accumulation.Our findings uncover a previously uncharacterized MAPK cascade module,NtMEKK1b-NtMPKK2a-NtMPK4,that regulates nicotine biosynthesis,highlighting the importance of posttranslational regulation in nicotine biosynthesis.展开更多
Gastric carcinoma(GC)is a malignancy with multifactorial involvement,multicellular regulation,and multistage evolution.The classic Correa's cascade of intestinal GC specifies a trilogy of malignant transformation ...Gastric carcinoma(GC)is a malignancy with multifactorial involvement,multicellular regulation,and multistage evolution.The classic Correa's cascade of intestinal GC specifies a trilogy of malignant transformation of the gastric mucosa,in which normal gastric mucosa gradually progresses from inactive or chronic active gastritis(Phase I)to gastric precancerous lesions(Phase II)and finally to GC(Phase III).Correa's cascade highlights the evolutionary pattern of GC and the importance of early intervention to prevent malignant transformation of the gastric mucosa.Intervening in early gastric mucosal lesions,i.e.,Phases I and II,will be the key strategy to prevent and treat GC.Natural products(NPs)have been an important source for drug development due to abundant sources,tremendous safety,and multiple pharmacodynamic mechanisms.This review is the first to investigate and summarize the multi-step effects and regulatory mechanisms of NPs on the Correa's cascade in gastric carcinogenesis.In Phase I,NPs modulate Helicobacter pylori urease activity,motility,adhesion,virulence factors,and drug resistance,thereby inhibiting H.pylori-induced gastric mucosal inflammation and oxidative stress,and facilitating ulcer healing.In Phase II,NPs modulate multiple pathways and mediators regulating gastric mucosal cell cycle,apoptosis,autophagy,and angiogenesis to reverse gastric precancerous lesions.In Phase III,NPs suppress cell proliferation,migration,invasion,angiogenesis,and cancer stem cells,induce apoptosis and autophagy,and enhance chemotherapeutic drug sensitivity for the treatment of GC.In contrast to existing work,we hope to uncover NPs with sequential therapeutic effects on multiple phases of GC development,providing new ideas for gastric cancer prevention,treatment,and drug development.展开更多
Broad area quantum cascade lasers(BA QCLs)have significant applications in many areas,but suffer from demanding pulse operating conditions and poor beam quality due to heat accumulation and generation of high order mo...Broad area quantum cascade lasers(BA QCLs)have significant applications in many areas,but suffer from demanding pulse operating conditions and poor beam quality due to heat accumulation and generation of high order modes.A structure of mini-array is adopted to improve the heat dissipation capacity and beam quality of BA QCLs.The active region is etched to form a multi-emitter and the channels are filled with In P:Fe,which acts as a lateral heat dissipation channel to improve the lateral heat dissipation efficiency.A device withλ~4.8μm,a peak output power of 122 W at 1.2%duty cycle with a pulse of 1.5μs is obtained in room temperature,with far-field single-lobed distribution.This result allows BA QCLs to obtain high peak power at wider pump pulse widths and higher duty cycle conditions,promotes the application of the mid-infrared laser operating in pulsed mode in th e field of standoff photoacoustic chemical detection,space optical communication,and so on.展开更多
In the process of power scaling large-area Quantum Cascade Lasers(QCLs),challenges such as degradation of beam quality and emission of multilobed far-field modes are frequently encountered.These issues become particul...In the process of power scaling large-area Quantum Cascade Lasers(QCLs),challenges such as degradation of beam quality and emission of multilobed far-field modes are frequently encountered.These issues become particularly pronounced with an increase in ridge width,resulting in multimode problems.To tackle this,an innovative multi ridge waveguide structure based on the principle of supersymmetry(SUSY)was proposed.This structure comprises a wider main waveguide in the center and two narrower auxiliary waveguides on either side.The high-order modes of the main waveguide are coupled with the modes of the auxiliary waveguides through mode-matching design,and the optical loss of the auxiliary waveguides suppresses these modes,thereby achieving fundamental mode lasing of the wider main waveguide.This paper employs the finite difference eigenmode(FDE)method to perform detailed structural modeling and simulation optimization of the 4.6μm wavelength quantum cascade laser,successfully achieving a single transverse mode QCL with a ridge width of 10μm.In comparison to the traditional single-mode QCL(with a ridge width of about 5μm),the MRW structure has the potential to increase the gain area of the laser by 100%.This offers a novel design concept and methodology for enhancing the single-mode luminous power of mid-infrared quantum cascade lasers,which is of considerable significance.展开更多
[Objective]The construction of weirs changes the hydraulic characteristics of rivers and affects the structure of phytoplankton communities and the health of aquatic ecosystems in the river.This study aims to explore ...[Objective]The construction of weirs changes the hydraulic characteristics of rivers and affects the structure of phytoplankton communities and the health of aquatic ecosystems in the river.This study aims to explore the nonlinear response relationship between phytoplankton community structure and its driving factors in spring and autumn in Furong Creek under the construction of cascade weirs.[Methods]The structure of phytoplankton communities and related environmental factors were investigated in Furong Creek from 2023 to 2024.This study focused on the analysis of the changes of nutrient concentrations and biomass of phytoplankton in autumn and spring within the same dry season in Furong Creek.Redundancy analysis was used to identify the key factors influencing the structure of phytoplankton communities.The MIKE 11 model was employed to simulate the hydrodynamic changes in the river.Combined with total nitrogen and permanganate index,a GAM model of phytoplankton diversity index and hydrodynamic factors was developed,and the change of phytoplankton diversity after the optimized layout of the cascade weirs was fitted.[Results]The result showed that the annual average value of Shannon-Wiener diversity index of phytoplankton in Furong Creek was 2.79,which was in a state of mild pollution.A total of 239 species from 95 genera in 8 phyla were identified.Among the phytoplankton,Chlorophyta was the dominant group throughout the year in Furong Creek,followed by Bacillariophyta and Cyanophyta.The cell abundance of phytoplankton ranged from 3.11 to 20.64 mg/L and from 0.23 to 6.31 mg/L in spring and autumn,which indicated a clear seasonal succession of phytoplankton community structure.Compared with autumn,the relative abundance of Cyanophyta significantly decreased in spring across the whole river section,while Chrysophyta and Dinophyta showed significant increase at some monitoring sites,leading to water bloom phenomenon and a noticeable decline in the diversity of phytoplankton.The dominant species in the water bodies throughout the year were Cyclotella catenata,Chlorella vulgaris,Scenedesmus bijuga,Scenedesmus quadricauda,Chroomonas acuta,Cryptomonas ovata,and Cryptomonas erosa.Redundancy analysis(RDA)showed that hydrodynamic factors(v,h)and water environmental factors(TN,COD_(Mn))were the main influencing factors of phytoplankton community structure.[Conclusion]The result show that the nutrient concentration,phytoplankton biomass,and density in Furong Creek in spring are significantly higher than in autumn.The GAM model,constructed by combining hydrodynamic and environmental factors,can effectively reflect the nonlinear relationship between phytoplankton diversity index and its driving factors.In spring,with an increase in nutrient concentration,the habitat conditions of low flow speed and high water depths formed by overflow weirs will lead to a decrease in the Shannon-Wiener index of phytoplankton and an intensified risk of eutrophication.However,a reasonable layout scheme of cascade weirs will improve the diversity of phytoplankton and reduce the risk of eutrophication in the river.The findings of this study can help deepen the understanding of the ecological and environmental effects of cascade weir construction in the river.展开更多
Organoselenium and pyrazole compounds are important scaffolds in pharmaceutical molecules.Herein,an electrochemical multicomponent one-pot cascade reaction of hydrazide,pentane-2,4-diones and diselenides has been esta...Organoselenium and pyrazole compounds are important scaffolds in pharmaceutical molecules.Herein,an electrochemical multicomponent one-pot cascade reaction of hydrazide,pentane-2,4-diones and diselenides has been established to construct 4-selenylacylpyrazoles.It is worth noting that for this efficient and green protocol,neither metal catalysts nor external oxidants are required.Moreover,this process exhibits step economy,ease of scale up and high yields to deliver various 4-selenylacylpyrazoles.展开更多
A novel synthesis of C2-spiroindoline derivatives based on the cascade reaction of 2-aryl-3H-indoles with cyclo- propanols is presented. The formation of product involves Rh(III)-catalyzed aryl C(sp2)—H bond alkylati...A novel synthesis of C2-spiroindoline derivatives based on the cascade reaction of 2-aryl-3H-indoles with cyclo- propanols is presented. The formation of product involves Rh(III)-catalyzed aryl C(sp2)—H bond alkylation of 2-aryl- 3H-indole, which is followed by intramolecular spiroannulation. In this tandem process, cyclopropanol acts as not only an alkylating agent but also a masked nucleophile to take part in the construction of the spirocyclic scaffold. Meanwhile, air acts as an economical and sustainable oxidant to promote the regeneration of the active catalyst. By using this method, hybrid compounds containing the central scaffolds of some clinical drugs were prepared effectively. In general, this newly developed method has advantages such as easily obtainable substrates, concise synthetic procedure, excellent atom-economy, good compatibility with diverse functional groups and ready scalability.展开更多
Chiral cyclic amino alcohols with contiguous stereocenters are key building blocks in the synthesis of bioactive molecules and pharmaceuticals.Artificial cascade biocatalysis represents an attractive method for the sy...Chiral cyclic amino alcohols with contiguous stereocenters are key building blocks in the synthesis of bioactive molecules and pharmaceuticals.Artificial cascade biocatalysis represents an attractive method for the synthesis of chiral molecules bearing multiple stereocenters from readily available materials.Here we reported an artificial cascade biocatalysis comprising an epoxide hydrolase,an alcohol dehydrogenase,and a reductive aminase or an amine dehydrogenase.It can be utilized to access all four stereoisomers of 2-aminocyclohexanol with two contiguous stereocenters in high yields(up to 95%)and excellent stereoselectivity(up to 98%de)starting from readily available cyclohexene oxide without isolation of the intermediates.Additionally,the biocatalytic cascade has been successfully extended to the production of structurally diverse 2-(alkylamino)cyclohexanols by replacing ammonia with different organic amines.展开更多
Herein,anthracene-pyridinium derivative(A1)is synthesized to assemble with amphiphilic sulfonatocalix[4]arene(SC4AD)with a porous cavity through electrostatic interaction,exhibiting enhanced fluorescence emission and ...Herein,anthracene-pyridinium derivative(A1)is synthesized to assemble with amphiphilic sulfonatocalix[4]arene(SC4AD)with a porous cavity through electrostatic interaction,exhibiting enhanced fluorescence emission and multipath fluorescence resonance energy transfer(FRET)with organic dyes(EY,Ni R or Cy5.5).In this nanoassembly,A1/SC4AD first transfers the energy to dye EY(first acceptor),and then delivers it to Ni R(second acceptor),which further transfers the energy to Cy5.5(third acceptor),accompanying with an emission ranging from 535 nm to 570 nm,then to 638 nm,and finally to near-infrared emission at 717 nm.Compared to one-step FRET(43.0%),the three-step FRET system shows higher energy transfer efficiency(FRET Ⅰ:84.9%,FRET Ⅱ:81.4%,FRET Ⅲ:66.9%).The donor/acceptor ratio is 3000(A1):20(EY):8(Ni R):5(Cy5.5),together with an antenna effect of 2.3.Additionally,diverse two-step cascade light-harvesting systems are successfully fabricated via tuning combination of dye acceptors.We believe that this multipath light-harvesting assembly will provide a direction for designing multiple sequential FRET and artificial light-harvesting systems.展开更多
Deprivation of glucose and lactate provides an effective pathway to terminate the nutrients supplement for tumor growth.In this work,biomimetic nanozymes called m@BGLC are constructed for catalytic tumor inhibition th...Deprivation of glucose and lactate provides an effective pathway to terminate the nutrients supplement for tumor growth.In this work,biomimetic nanozymes called m@BGLC are constructed for catalytic tumor inhibition through nutrients deprivation and oxidative damage induction.Concretely,the catalytic enzymes of glucose oxidase(GOx),lactate oxidase(LOx)and chloroperoxidase(CPO)are precrosslinked with bovine serum albumin(BSA)to construct nanozymes,which are then biomimetic functionalized with cancer cell membrane to prepare m@BGLC.Benefiting from the biomimetic camouflage with homologous cell membrane,m@BGLC inherit homotypic binding and immune escape abilities,facilitating the tumor targeting accumulation and preferable cell internalization for improved drug delivery efficiency.Subsequently,under the cascade catalysis of nanozymes,m@BGLC consume glucose and lactate for tumor starvation therapy through nutrients deprivation,and meanwhile,the resulting hyprochloric acid(HClO)causes an oxidative damage of cells to synergistically inhibit tumor growth.In vitro and in vivo findings demonstrate a robust tumor eradication effect of m@BGLC without obvious adverse reactions via the targeted combination therapy.Such cascade catalytic nanomedicine may inspire the development of sophisticated strategies for tumor combination therapy under unfavorable tumor microenvironments.展开更多
Coal and gas outbursts constitute a critical hazard in underground mining operations,characterized by rapid transitions from localized instability to catastrophic failure.Understanding the relationship between initial...Coal and gas outbursts constitute a critical hazard in underground mining operations,characterized by rapid transitions from localized instability to catastrophic failure.Understanding the relationship between initial characteristics and final outburst scale remains a fundamental challenge in geomechanics.This study conceptualizes outbursts as deterministic cascade systems through integrated physical simulations combining high-sensitivity infrasound monitoring with energy analysis under controlled gas pressure(0.5–1.0 MPa)and confining stress(5–10 MPa)conditions.Our complementary analytical algorithms—the absolute amplitude integral and predominant period function—revealed characteristic step-wise patterns in outburst development.Quantitative analysis established a robust correlation(R2=0.91)between initial acoustic response and final outburst intensity.Energy analysis demonstrated that gas expansion dominates the outburst process(91.81%–99.09%of total energy),with desorption gas contributing 59.1%–77.7%.Time-frequency analysis showed systematic frequency migration from high(12–15 Hz)to low(4–8 Hz)bands during outburst progression,reflecting hierarchical spatial scale expansion.The concentrated energy release(>20%of total)within initial 0.2 s provides a mechanistic basis for the deterministic nature of outburst evolution.These mechanistic insights establish a quantitative framework for developing physics-based monitoring protocols and risk assessment methodologies applicable to underground coal mining operations.展开更多
The thermal conductivity of plasma-facing materials(PFM)exposed to intense radiation is a critical concern for the reliable usage of materials in fusion reactors.However,limited research has been performed regarding t...The thermal conductivity of plasma-facing materials(PFM)exposed to intense radiation is a critical concern for the reliable usage of materials in fusion reactors.However,limited research has been performed regarding the thermal conductivity of structures that rapidly change in a short time during collision cascade processes under irradiation.In this study,we employed the tight-binding(TB)method to investigate the electronic thermal conductivity(κ_(e))of tungsten-based systems during various cascading processes.We found thatκ_(e) values sharply decrease within the initial 0.3 picoseconds and then partially recover at a slow pace;this is closely linked to the evolution of defects and microstructural distortions.The increase in the initial kinetic energy of the primary knock-on atom and the presence of a high concentration of hydrogen atoms further decrease theκ_(e) values.Conversely,higher temperatures have a significant positive effect onκ_(e).Furthermore,the presence of a grain boundary∑5[001](130)substantially reducesκ_(e),whereas the absorption effect of point defects by the grain boundary has little influence onκ_(e) during cascades.Our findings provide a theoretical basis for evaluating changes in the thermal conductivity performance of PFMs during their usage in nuclear fusion reactors.展开更多
Independent cascade(IC)models,by simulating how one node can activate another,are important tools for studying the dynamics of information spreading in complex networks.However,traditional algorithms for the IC model ...Independent cascade(IC)models,by simulating how one node can activate another,are important tools for studying the dynamics of information spreading in complex networks.However,traditional algorithms for the IC model implementation face significant efficiency bottlenecks when dealing with large-scale networks and multi-round simulations.To settle this problem,this study introduces a GPU-based parallel independent cascade(GPIC)algorithm,featuring an optimized representation of the network data structure and parallel task scheduling strategies.Specifically,for this GPIC algorithm,we propose a network data structure tailored for GPU processing,thereby enhancing the computational efficiency and the scalability of the IC model.In addition,we design a parallel framework that utilizes the full potential of GPU's parallel processing capabilities,thereby augmenting the computational efficiency.The results from our simulation experiments demonstrate that GPIC not only preserves accuracy but also significantly boosts efficiency,achieving a speedup factor of 129 when compared to the baseline IC method.Our experiments also reveal that when using GPIC for the independent cascade simulation,100-200 simulation rounds are sufficient for higher-cost studies,while high precision studies benefit from 500 rounds to ensure reliable results,providing empirical guidance for applying this new algorithm to practical research.展开更多
Intramolecular end-to-end reactions of long-chain linear precursors remain challenging due to their inherent tendency to undergo intermolecular reactions.Herein,we investigated the cascade hydrolysis and intramolecula...Intramolecular end-to-end reactions of long-chain linear precursors remain challenging due to their inherent tendency to undergo intermolecular reactions.Herein,we investigated the cascade hydrolysis and intramolecular cyclization reactions of three vips with varying lengths within the well-defined nanocavities of cavitands in aqueous solution.Driven by hydrophobic effect,these vips were encapsulated within the dimeric capsules,adopting distinct conformations and orientations due to spatial constraints.Specifically,the shorter vip maintained an extended linear geometry,whereas the longer vips adopted a folded binding mode.Upon initiating the reaction,the terminal residue of the shorter vip displayed lower reactivity,while the longer vips,preorganized within the cavity,underwent efficient cyclization,resulting in significant differences in reaction kinetics.Furthermore,electrostatic potential fields played a critical role in modulating reaction rates,with the positively charged cavitand accelerating the reaction more efficiently compared to its negatively charged counterpart,likely due to stabilization of the anionic transition state.This study provides an effective strategy for designing enzymemimetic nanoreactors through the utilization of well-defined nanospaces.展开更多
文摘One of the main issues in designing optimum tapered cascades for uranium enrichment for annual fuel production in a power reactor is whether to employ large(fat)or small(thin)cascades.What will be the permissible and optimal ranges of the number of machines that can be used in a cascade?For the first time,the permissible and optimal ranges of the number of gas centrifuges that can be utilized in a cascade were investigated using two types of centrifuges,and the performance of small and large tapered cascades was discussed.The particle swarm optimization algorithm(PSO)has been used to optimize tapered cascades.The results show:(1)For the first centrifuge,41 cascades(91≤n≤4897)and for the second centrifuge,49 cascades(18≤n≤3839)with small and large sizes can be used in enrichment facilities,and the best cascade for them has 530(with 23 stages)and 39(with 7 stages)centrifuges,respectively.(2)For both centrifuges,when 600≤n(number of centrifuges=n),the large cascade performance changes are relatively insignificant.(3)For both types of gas centrifuges,the annual los s of separation power in enrichment facilities is approximately 1.25%-4.82%of the total separation work required.
基金National Natural Science Foundation of China (NSFC) (No.22131008)the Haihe Laboratory of Sustainable Chemical Transformations for financial support。
文摘Photo-responsive supramolecular assembly especially supramolecular hydrogels with tunable luminescence show a promising application potential in writable information recording and display materials.Herein,we report photo-responsive reversible multicolor supramolecular hydrogel with near-infrared emission,which is constructed by cucurbit[7]uril(CB[7]),cyanostilbene derivative(DAC)and Laponite XLG(LP)via supramolecular cascade assembly.Compared with the free vip molecule DAC,the confinement of macrocycle CB[7]achieve effective near-infrared fluorescence in the aqueous phase from scratch,and the subsequent cascade assembly with LP further restrict the molecular rotation of the DAC,which not only result in a substantial enhancement of the fluorescence intensity,but is also endowed with light-controlled fluorescence on/off both in the solution and hydrogel states.Further,8-hydroxy-1,3,6-pyrenetrisulfonic acid trisodium salt(HPTS)is introduced in the cascade assembly to fabricated photocontrollable reversible multicolor luminescence supramolecular hydrogel between red and green induced by Förster resonance energy transfer,which is successfully employed in reversible multiple information encryption.
基金funds from Natural Science Foundation of Guangxi Province(Nos.2023GXNSFBA026304,2023GXNSFDA026063)the Guangxi Science and Technology Base and Special Talents(No.Guike AD20159047).
文摘A visible-light induced cascade sulfonation/cyclization reaction of 3-allyl-2-arylquinazolinones employing water as an environmentally friendly solvent was revealed.This transition metal-free protocol,using 9-mesityl-10-methylacridinium perchlorate as the photocatalyst,represents a masterly tactic for the synthesis of sulfonated dihydroisoquinolino[1,2-b]quinazolinones featuring mild conditions,facile operation,and broad substrate scope.
基金supported partially by the Kentucky Tobacco Research and Development Center(KTRDC),University of Kentucky.
文摘The evolutionarily conserved mitogen-activated protein kinase(MAPK)cascades relay extracellular signals into cells,triggering a variety of cellular responses.We previously revealed NtMPK4 as a positive regulator of nicotine biosynthesis;however,its upstream regulation remains unclear.Here,we characterized a MAPK cascade,comprising NtMEKK1b,NtMPKK2a,and NtMPK4,that promotes nicotine biosynthesis.This signaling module transduces external cues,including jasmonate and pathogen elicitors such as flg22,into post-translational modifications that enhance transcriptional activity and pathway gene expression.NtMPKK2a physically interacts with and phosphorylates NtMPK4 in vivo,confirming its role as an upstream kinase.RNAi-mediated silencing of NtMPKK2a significantly reduced the expression of nicotine pathway genes and decreased nicotine accumulation,whereas induced-overexpression of NtMPKK2a upregulated nicotine pathway genes and increased nicotine contents in tobacco hairy roots.Overexpression of NtMPKK2a in tobacco cells enhanced the transactivation activity of a NIC2-locus Ethylene Response Factor NtERF221 on Putrescine N-methyltransferase(NtPMT)promotor,further supporting its role in promoting nicotine biosynthesis.Furthermore,we identified NtMEKK1b,a tobacco MEKK that interacts with NtMAPKK2a in yeast cells.Knock-down of NtMEKK1b in transgenic tobacco plants attenuated the expression of nicotine pathway genes and reduced nicotine contents,whereas induced-overexpression of NtMEKK1b upregulated gene expression and nicotine accumulation.Our findings uncover a previously uncharacterized MAPK cascade module,NtMEKK1b-NtMPKK2a-NtMPK4,that regulates nicotine biosynthesis,highlighting the importance of posttranslational regulation in nicotine biosynthesis.
基金supported by the Chengdu University of Traditional Chinese Medicine"Xinglin Scholars"Program,China(Grant No.:MPRC2023014).
文摘Gastric carcinoma(GC)is a malignancy with multifactorial involvement,multicellular regulation,and multistage evolution.The classic Correa's cascade of intestinal GC specifies a trilogy of malignant transformation of the gastric mucosa,in which normal gastric mucosa gradually progresses from inactive or chronic active gastritis(Phase I)to gastric precancerous lesions(Phase II)and finally to GC(Phase III).Correa's cascade highlights the evolutionary pattern of GC and the importance of early intervention to prevent malignant transformation of the gastric mucosa.Intervening in early gastric mucosal lesions,i.e.,Phases I and II,will be the key strategy to prevent and treat GC.Natural products(NPs)have been an important source for drug development due to abundant sources,tremendous safety,and multiple pharmacodynamic mechanisms.This review is the first to investigate and summarize the multi-step effects and regulatory mechanisms of NPs on the Correa's cascade in gastric carcinogenesis.In Phase I,NPs modulate Helicobacter pylori urease activity,motility,adhesion,virulence factors,and drug resistance,thereby inhibiting H.pylori-induced gastric mucosal inflammation and oxidative stress,and facilitating ulcer healing.In Phase II,NPs modulate multiple pathways and mediators regulating gastric mucosal cell cycle,apoptosis,autophagy,and angiogenesis to reverse gastric precancerous lesions.In Phase III,NPs suppress cell proliferation,migration,invasion,angiogenesis,and cancer stem cells,induce apoptosis and autophagy,and enhance chemotherapeutic drug sensitivity for the treatment of GC.In contrast to existing work,we hope to uncover NPs with sequential therapeutic effects on multiple phases of GC development,providing new ideas for gastric cancer prevention,treatment,and drug development.
文摘Broad area quantum cascade lasers(BA QCLs)have significant applications in many areas,but suffer from demanding pulse operating conditions and poor beam quality due to heat accumulation and generation of high order modes.A structure of mini-array is adopted to improve the heat dissipation capacity and beam quality of BA QCLs.The active region is etched to form a multi-emitter and the channels are filled with In P:Fe,which acts as a lateral heat dissipation channel to improve the lateral heat dissipation efficiency.A device withλ~4.8μm,a peak output power of 122 W at 1.2%duty cycle with a pulse of 1.5μs is obtained in room temperature,with far-field single-lobed distribution.This result allows BA QCLs to obtain high peak power at wider pump pulse widths and higher duty cycle conditions,promotes the application of the mid-infrared laser operating in pulsed mode in th e field of standoff photoacoustic chemical detection,space optical communication,and so on.
基金Supported by the National Natural Science Foundation of China(62105039)。
文摘In the process of power scaling large-area Quantum Cascade Lasers(QCLs),challenges such as degradation of beam quality and emission of multilobed far-field modes are frequently encountered.These issues become particularly pronounced with an increase in ridge width,resulting in multimode problems.To tackle this,an innovative multi ridge waveguide structure based on the principle of supersymmetry(SUSY)was proposed.This structure comprises a wider main waveguide in the center and two narrower auxiliary waveguides on either side.The high-order modes of the main waveguide are coupled with the modes of the auxiliary waveguides through mode-matching design,and the optical loss of the auxiliary waveguides suppresses these modes,thereby achieving fundamental mode lasing of the wider main waveguide.This paper employs the finite difference eigenmode(FDE)method to perform detailed structural modeling and simulation optimization of the 4.6μm wavelength quantum cascade laser,successfully achieving a single transverse mode QCL with a ridge width of 10μm.In comparison to the traditional single-mode QCL(with a ridge width of about 5μm),the MRW structure has the potential to increase the gain area of the laser by 100%.This offers a novel design concept and methodology for enhancing the single-mode luminous power of mid-infrared quantum cascade lasers,which is of considerable significance.
文摘[Objective]The construction of weirs changes the hydraulic characteristics of rivers and affects the structure of phytoplankton communities and the health of aquatic ecosystems in the river.This study aims to explore the nonlinear response relationship between phytoplankton community structure and its driving factors in spring and autumn in Furong Creek under the construction of cascade weirs.[Methods]The structure of phytoplankton communities and related environmental factors were investigated in Furong Creek from 2023 to 2024.This study focused on the analysis of the changes of nutrient concentrations and biomass of phytoplankton in autumn and spring within the same dry season in Furong Creek.Redundancy analysis was used to identify the key factors influencing the structure of phytoplankton communities.The MIKE 11 model was employed to simulate the hydrodynamic changes in the river.Combined with total nitrogen and permanganate index,a GAM model of phytoplankton diversity index and hydrodynamic factors was developed,and the change of phytoplankton diversity after the optimized layout of the cascade weirs was fitted.[Results]The result showed that the annual average value of Shannon-Wiener diversity index of phytoplankton in Furong Creek was 2.79,which was in a state of mild pollution.A total of 239 species from 95 genera in 8 phyla were identified.Among the phytoplankton,Chlorophyta was the dominant group throughout the year in Furong Creek,followed by Bacillariophyta and Cyanophyta.The cell abundance of phytoplankton ranged from 3.11 to 20.64 mg/L and from 0.23 to 6.31 mg/L in spring and autumn,which indicated a clear seasonal succession of phytoplankton community structure.Compared with autumn,the relative abundance of Cyanophyta significantly decreased in spring across the whole river section,while Chrysophyta and Dinophyta showed significant increase at some monitoring sites,leading to water bloom phenomenon and a noticeable decline in the diversity of phytoplankton.The dominant species in the water bodies throughout the year were Cyclotella catenata,Chlorella vulgaris,Scenedesmus bijuga,Scenedesmus quadricauda,Chroomonas acuta,Cryptomonas ovata,and Cryptomonas erosa.Redundancy analysis(RDA)showed that hydrodynamic factors(v,h)and water environmental factors(TN,COD_(Mn))were the main influencing factors of phytoplankton community structure.[Conclusion]The result show that the nutrient concentration,phytoplankton biomass,and density in Furong Creek in spring are significantly higher than in autumn.The GAM model,constructed by combining hydrodynamic and environmental factors,can effectively reflect the nonlinear relationship between phytoplankton diversity index and its driving factors.In spring,with an increase in nutrient concentration,the habitat conditions of low flow speed and high water depths formed by overflow weirs will lead to a decrease in the Shannon-Wiener index of phytoplankton and an intensified risk of eutrophication.However,a reasonable layout scheme of cascade weirs will improve the diversity of phytoplankton and reduce the risk of eutrophication in the river.The findings of this study can help deepen the understanding of the ecological and environmental effects of cascade weir construction in the river.
基金Project supported by the Young Talent Fund of Association for Science and Technology in Shaanxi(No.20220609)the Natural Science Foundation Research Project of Shaanxi Province(No.2025JC-YBQN-129)+3 种基金the Science and Technology Planning Project of Yan City(No.2022SLSFGG-005)the National College Students'Innovation and Entrepreneurship Training Program(No.202510719063)the Youth Innovation Team Project of Shaanxi Provincial Education Department(No.23JP193)the Youth Innovation Team of Shaanxi Universities。
文摘Organoselenium and pyrazole compounds are important scaffolds in pharmaceutical molecules.Herein,an electrochemical multicomponent one-pot cascade reaction of hydrazide,pentane-2,4-diones and diselenides has been established to construct 4-selenylacylpyrazoles.It is worth noting that for this efficient and green protocol,neither metal catalysts nor external oxidants are required.Moreover,this process exhibits step economy,ease of scale up and high yields to deliver various 4-selenylacylpyrazoles.
文摘A novel synthesis of C2-spiroindoline derivatives based on the cascade reaction of 2-aryl-3H-indoles with cyclo- propanols is presented. The formation of product involves Rh(III)-catalyzed aryl C(sp2)—H bond alkylation of 2-aryl- 3H-indole, which is followed by intramolecular spiroannulation. In this tandem process, cyclopropanol acts as not only an alkylating agent but also a masked nucleophile to take part in the construction of the spirocyclic scaffold. Meanwhile, air acts as an economical and sustainable oxidant to promote the regeneration of the active catalyst. By using this method, hybrid compounds containing the central scaffolds of some clinical drugs were prepared effectively. In general, this newly developed method has advantages such as easily obtainable substrates, concise synthetic procedure, excellent atom-economy, good compatibility with diverse functional groups and ready scalability.
文摘Chiral cyclic amino alcohols with contiguous stereocenters are key building blocks in the synthesis of bioactive molecules and pharmaceuticals.Artificial cascade biocatalysis represents an attractive method for the synthesis of chiral molecules bearing multiple stereocenters from readily available materials.Here we reported an artificial cascade biocatalysis comprising an epoxide hydrolase,an alcohol dehydrogenase,and a reductive aminase or an amine dehydrogenase.It can be utilized to access all four stereoisomers of 2-aminocyclohexanol with two contiguous stereocenters in high yields(up to 95%)and excellent stereoselectivity(up to 98%de)starting from readily available cyclohexene oxide without isolation of the intermediates.Additionally,the biocatalytic cascade has been successfully extended to the production of structurally diverse 2-(alkylamino)cyclohexanols by replacing ammonia with different organic amines.
基金financially supported by the National Natural Science Foundation of China(No.22131008)。
文摘Herein,anthracene-pyridinium derivative(A1)is synthesized to assemble with amphiphilic sulfonatocalix[4]arene(SC4AD)with a porous cavity through electrostatic interaction,exhibiting enhanced fluorescence emission and multipath fluorescence resonance energy transfer(FRET)with organic dyes(EY,Ni R or Cy5.5).In this nanoassembly,A1/SC4AD first transfers the energy to dye EY(first acceptor),and then delivers it to Ni R(second acceptor),which further transfers the energy to Cy5.5(third acceptor),accompanying with an emission ranging from 535 nm to 570 nm,then to 638 nm,and finally to near-infrared emission at 717 nm.Compared to one-step FRET(43.0%),the three-step FRET system shows higher energy transfer efficiency(FRET Ⅰ:84.9%,FRET Ⅱ:81.4%,FRET Ⅲ:66.9%).The donor/acceptor ratio is 3000(A1):20(EY):8(Ni R):5(Cy5.5),together with an antenna effect of 2.3.Additionally,diverse two-step cascade light-harvesting systems are successfully fabricated via tuning combination of dye acceptors.We believe that this multipath light-harvesting assembly will provide a direction for designing multiple sequential FRET and artificial light-harvesting systems.
基金financial support of Guangdong Basic and Applied Basic Research Foundation(No.2022B1515020095)National Natural Science Foundation of China(No.52073140)。
文摘Deprivation of glucose and lactate provides an effective pathway to terminate the nutrients supplement for tumor growth.In this work,biomimetic nanozymes called m@BGLC are constructed for catalytic tumor inhibition through nutrients deprivation and oxidative damage induction.Concretely,the catalytic enzymes of glucose oxidase(GOx),lactate oxidase(LOx)and chloroperoxidase(CPO)are precrosslinked with bovine serum albumin(BSA)to construct nanozymes,which are then biomimetic functionalized with cancer cell membrane to prepare m@BGLC.Benefiting from the biomimetic camouflage with homologous cell membrane,m@BGLC inherit homotypic binding and immune escape abilities,facilitating the tumor targeting accumulation and preferable cell internalization for improved drug delivery efficiency.Subsequently,under the cascade catalysis of nanozymes,m@BGLC consume glucose and lactate for tumor starvation therapy through nutrients deprivation,and meanwhile,the resulting hyprochloric acid(HClO)causes an oxidative damage of cells to synergistically inhibit tumor growth.In vitro and in vivo findings demonstrate a robust tumor eradication effect of m@BGLC without obvious adverse reactions via the targeted combination therapy.Such cascade catalytic nanomedicine may inspire the development of sophisticated strategies for tumor combination therapy under unfavorable tumor microenvironments.
基金funded by the National Natural Science Foundation of China(No.52464016)the Guizhou Provincial Foundation Research Project(No.QKHJC-[2024]Youth 141)+1 种基金the Guizhou Provincial Basic Research Program(No.MS[2025]632)the Young Researcher Growth Project of Guizhou Provincial Department of Education(No.QJJ-[2024]25).
文摘Coal and gas outbursts constitute a critical hazard in underground mining operations,characterized by rapid transitions from localized instability to catastrophic failure.Understanding the relationship between initial characteristics and final outburst scale remains a fundamental challenge in geomechanics.This study conceptualizes outbursts as deterministic cascade systems through integrated physical simulations combining high-sensitivity infrasound monitoring with energy analysis under controlled gas pressure(0.5–1.0 MPa)and confining stress(5–10 MPa)conditions.Our complementary analytical algorithms—the absolute amplitude integral and predominant period function—revealed characteristic step-wise patterns in outburst development.Quantitative analysis established a robust correlation(R2=0.91)between initial acoustic response and final outburst intensity.Energy analysis demonstrated that gas expansion dominates the outburst process(91.81%–99.09%of total energy),with desorption gas contributing 59.1%–77.7%.Time-frequency analysis showed systematic frequency migration from high(12–15 Hz)to low(4–8 Hz)bands during outburst progression,reflecting hierarchical spatial scale expansion.The concentrated energy release(>20%of total)within initial 0.2 s provides a mechanistic basis for the deterministic nature of outburst evolution.These mechanistic insights establish a quantitative framework for developing physics-based monitoring protocols and risk assessment methodologies applicable to underground coal mining operations.
基金supported by the Collaborative Innovation Program of Hefei Science Center of CAS(No.2022HSC-CIP007)。
文摘The thermal conductivity of plasma-facing materials(PFM)exposed to intense radiation is a critical concern for the reliable usage of materials in fusion reactors.However,limited research has been performed regarding the thermal conductivity of structures that rapidly change in a short time during collision cascade processes under irradiation.In this study,we employed the tight-binding(TB)method to investigate the electronic thermal conductivity(κ_(e))of tungsten-based systems during various cascading processes.We found thatκ_(e) values sharply decrease within the initial 0.3 picoseconds and then partially recover at a slow pace;this is closely linked to the evolution of defects and microstructural distortions.The increase in the initial kinetic energy of the primary knock-on atom and the presence of a high concentration of hydrogen atoms further decrease theκ_(e) values.Conversely,higher temperatures have a significant positive effect onκ_(e).Furthermore,the presence of a grain boundary∑5[001](130)substantially reducesκ_(e),whereas the absorption effect of point defects by the grain boundary has little influence onκ_(e) during cascades.Our findings provide a theoretical basis for evaluating changes in the thermal conductivity performance of PFMs during their usage in nuclear fusion reactors.
基金support from the National Natural Science Foundation of China(Grant No.T2293771)the STI 2030-Major Projects(Grant No.2022ZD0211400)the Sichuan Province Outstanding Young Scientists Foundation(Grant No.2023NSFSC1919)。
文摘Independent cascade(IC)models,by simulating how one node can activate another,are important tools for studying the dynamics of information spreading in complex networks.However,traditional algorithms for the IC model implementation face significant efficiency bottlenecks when dealing with large-scale networks and multi-round simulations.To settle this problem,this study introduces a GPU-based parallel independent cascade(GPIC)algorithm,featuring an optimized representation of the network data structure and parallel task scheduling strategies.Specifically,for this GPIC algorithm,we propose a network data structure tailored for GPU processing,thereby enhancing the computational efficiency and the scalability of the IC model.In addition,we design a parallel framework that utilizes the full potential of GPU's parallel processing capabilities,thereby augmenting the computational efficiency.The results from our simulation experiments demonstrate that GPIC not only preserves accuracy but also significantly boosts efficiency,achieving a speedup factor of 129 when compared to the baseline IC method.Our experiments also reveal that when using GPIC for the independent cascade simulation,100-200 simulation rounds are sufficient for higher-cost studies,while high precision studies benefit from 500 rounds to ensure reliable results,providing empirical guidance for applying this new algorithm to practical research.
基金funded by the National Natural Science Foundation of China(Nos.22271154,M-0411)the China Postdoctoral Science Foundation(No.2023M731658)+2 种基金the Science Fund for Distinguished Young Scholars of Jiangsu Province(No.BK20240078)the Innovation Support Program of Jiangsu Province(No.BZ2023055)the High-Performance Computing Platform of Peking Uniersity。
文摘Intramolecular end-to-end reactions of long-chain linear precursors remain challenging due to their inherent tendency to undergo intermolecular reactions.Herein,we investigated the cascade hydrolysis and intramolecular cyclization reactions of three vips with varying lengths within the well-defined nanocavities of cavitands in aqueous solution.Driven by hydrophobic effect,these vips were encapsulated within the dimeric capsules,adopting distinct conformations and orientations due to spatial constraints.Specifically,the shorter vip maintained an extended linear geometry,whereas the longer vips adopted a folded binding mode.Upon initiating the reaction,the terminal residue of the shorter vip displayed lower reactivity,while the longer vips,preorganized within the cavity,underwent efficient cyclization,resulting in significant differences in reaction kinetics.Furthermore,electrostatic potential fields played a critical role in modulating reaction rates,with the positively charged cavitand accelerating the reaction more efficiently compared to its negatively charged counterpart,likely due to stabilization of the anionic transition state.This study provides an effective strategy for designing enzymemimetic nanoreactors through the utilization of well-defined nanospaces.
