Conversion between different types of entangled states is an interesting problem in quantum mechanics.But research on the conversion between the Greenberger-Horne-Zeilinger(GHZ)state and Knill-Laflamme-Milburn(KLM)sta...Conversion between different types of entangled states is an interesting problem in quantum mechanics.But research on the conversion between the Greenberger-Horne-Zeilinger(GHZ)state and Knill-Laflamme-Milburn(KLM)state in an atomic system has not been reported.In this paper,we propose a scheme to realize the interconversion(one-step)between the GHZ state and KLM state with Rydberg atoms.By utilizing Rydberg-mediated interactions,we simplify the system.By combining a Lie-transform-based pulse design,the evolution path is built up to realize interconversion of the GHZ state and KLM state.The numerical simulation result shows that the present scheme is robust against decoherence and operational imperfection.展开更多
The relative conformer energies of glycine are evaluated by using a focal point analysis expressed as（HF→MP2→MP3→CCSD→CCSD（T））.The conformer abundances at various temperatures（298–500 K） are calculated base...The relative conformer energies of glycine are evaluated by using a focal point analysis expressed as（HF→MP2→MP3→CCSD→CCSD（T））.The conformer abundances at various temperatures（298–500 K） are calculated based on the relative energies and Boltzmann statistical thermostatistical analysis with and without considering internal hindered rotations.A comparison between the available Raman spectrum and the electron momentum spectrum confirms that the influence of rigid-rotor hindered rotation on the conformational proportions of glycine is considerable,especially for the IIIp structure.The conformational interconversions are discussed.It is found that with increasing temperature,the mole fraction of IIn keeps constant and Ip structure can convert into IVn and IIIp,leading to the decrease in the weight of Ip and the increase in the weights of IVn and IIIp conformers,which is in accordance with experimental observations.展开更多
Poly-NHC-based organometallic assemblies 3-PF_(6),3-SbF_(6) and 3-OTf were obtained and verified by NMR spectroscopy,ESI mass spectrometry and single-crystal X-ray diffraction analyses.Controllable structural intercon...Poly-NHC-based organometallic assemblies 3-PF_(6),3-SbF_(6) and 3-OTf were obtained and verified by NMR spectroscopy,ESI mass spectrometry and single-crystal X-ray diffraction analyses.Controllable structural interconversion was observed between the poly-NHC-based organometallic assemblies and their self-aggregated dimers in solution affected by concentration,solvent and metal ion.1H NMR spectra of assembly 3-PF_(6) in CD_(3)CN at different concentrations demonstrated controllable structural interconversion,and ^(19)F NMR spectrum of assembly 3-PF_(6) at high concentration further evidenced the presence of the free hexafluorophosphate anion and encapsulated hexafluorophosphate anion for its two sets of signals.In addition,single-crystal X-ray diffraction analysis provided clear evidence that in the solid state,two assemblies 3-PF_(6) were vertically stuck,forming a self-aggregated dimer with an encapsulated hexafluorophosphate anion.Investigating the reversible structural interconversion is beneficial for revealing the intrinsic nature on the atom level and paving the way to design the stimuli-responsive functional system.展开更多
BACKGROUND UDP-glucose 6-dehydrogenase(UGDH)is a key enzyme in glucuronic acid metabolism and acts as a key mediator in several cancer developmental signaling pathways.AIM To offer a more systematic and comprehensive ...BACKGROUND UDP-glucose 6-dehydrogenase(UGDH)is a key enzyme in glucuronic acid metabolism and acts as a key mediator in several cancer developmental signaling pathways.AIM To offer a more systematic and comprehensive elucidation of the involvement of UGDH in the onset and progression of various malignancies.METHODS The role of UGDH in cancer was investigated via public databases.The data were analyzed via various R packages and websites,including TISIDB,cBioPortal,STRING,Cytoscape,GSCALite,and CancerSEA.A rat hepatocellular carcinoma(HCC)model was established via the intraperitoneal injection of diethylnitrosamine.Hematoxylin-eosin staining,Masson staining,Ki67 and UGDH immunohistochemical staining,and ARG1 immunofluorescence staining of liver tissues were performed.Real-time quantitative PCR and Western blotting were used to detect UGDH expression.The UGDH gene was knocked down in Huh7 cells,and CCK8 and nude mouse tumor xenograft assays were performed.RESULTS High UGDH expression is associated with poor clinical outcomes in HCC,lung adenocarcinoma,lung squamous cell carcinoma,and sarcoma patients and is differentially expressed across molecular and immune subtypes.UGDH is primarily involved in the pentose and glucuronate interconversion pathway.Its expression is positively correlated with T helper,Tcm,and Th2 cells in most cancers.Moreover,experimental results demonstrated that UGDH expression is elevated in HCC tissues and that its downregulation inhibits HCC cell proliferation.CONCLUSION Our study revealed that UGDH could be a valuable prognostic biomarker and potential therapeutic target in many cancers,especially liver and lung cancer.UGDH could promote HCC cell proliferation,potentially by modulating the pentose and glucuronate interconversion pathways.展开更多
Orchestrating conflicting polymerization mechanisms in a single polymerization process through one external stimulus is a prerequisite to achieve in-situ selective synthesis of different monomers. Here we report an el...Orchestrating conflicting polymerization mechanisms in a single polymerization process through one external stimulus is a prerequisite to achieve in-situ selective synthesis of different monomers. Here we report an electrochemically controlled mechanism transformation that enables selective activation of living cationic or radical polymerization via an alternating voltage and dual electrocatalysts. Using identical mixed-monomer condition, a variety of desired block copolymer structures, including diblock, multiblock, random, and tapered copolymers can be obtained by simply varying the periods or phases of the alternating potential. Moreover, merging this electro-interconverted polymerization with a flow-chemistry technique can streamline preparation of functional polymer materials with complex multiblock structure. This study would offer a new vision on large-scale electrochemical synthesis of sequence-defined polymers.展开更多
The dynamic transformations of conformations and aromatic properties of [32]octaphyrins（1.0.1.0.1.0.1.0） through rotating the pyrrolic ring of the macrocycles are demonstrated by theoretical simulations in CH2Cl2 so...The dynamic transformations of conformations and aromatic properties of [32]octaphyrins（1.0.1.0.1.0.1.0） through rotating the pyrrolic ring of the macrocycles are demonstrated by theoretical simulations in CH2Cl2 solution. Facile multistep isomeriza- tions involving antiaromatic-Htickel and aromatic-Mobius topologies were also predicted by density functional theory （DFT）. The understanding of changes in topologies and aromaticities of free-base expanded porphrins may provide useful information to build new macrocycles with unique properties.展开更多
The interconversion between the two distinct isomers of methyl vinyl ether （MVE）, the formation of the primary ozonides from O3-initated reactions of MVE, the transformation between the primary ozonides, and the sub...The interconversion between the two distinct isomers of methyl vinyl ether （MVE）, the formation of the primary ozonides from O3-initated reactions of MVE, the transformation between the primary ozonides, and the subsequent fragmentation were studied using quantum chemical methods at the BHandHLYP/6311＋＋G（d,p） level of theory for optimized geometries and frequency calculations and at the QCISD/631G（d,p） level for the single point energy calculations. The rate coefficients were calculated for the temperature range 280-440 K by using the canonical transition state theory （TST）. For ozone addition to MVE, there are two different possibilities discussed on the basis of two different possible orientations for ozone attack. The results of the theoretical study indicate that although the synperiplanar-MVE is 7.11 kJ/mol more stable than the antiperiplanar-MVE, the antiperiplanar-MVE plays a more important role in formation of the primary ozonides because the primary ozonides formed from the ozone addition antiperiplanar-MVE are more stable and the energy barriers corresponding to transition states are lower. The intereonversion between the primary ozonides formed from the ozone addition to antiperiplanar-MVE is the most accessible compared with the transformations between other primary ozonides. The cleavage of the primary ozonides mainly leads to the formation of the CH2OO, which is in agreement with the experimental estimates. The calculated overall rate constant for the ozone-initiated reactions is 4.8× 10^-17 cm^3/（molecule.s） at 298.15 K, which agrees with the experimental value for ethyl vinyl ether.展开更多
A new method was developed in this work to account for inorganic Sb species interconversion during soil sample preparation and subsequent separation steps. The Sb(III) and Sb(V) concentrations at each investigated ste...A new method was developed in this work to account for inorganic Sb species interconversion during soil sample preparation and subsequent separation steps. The Sb(III) and Sb(V) concentrations at each investigated step in the analytical procedure were determined using species specific spikes (121Sb(III) with 81.18% and 123Sb(V) with 74.04% enrichment). The spiking of these enriched isotopes species solutions was done separately before soil sample extraction and before HPLC separation. Simply by subtracting the final concentration of each species done by on-line isotope dilution (ID) from its concentration at different stages of the analytical procedure done by species specific ID, the influence of each step on species transformation can be estimated. After optimization, the extraction procedure for inorganic Sb species 6% Sb(III) (1.3 RSD, n = 3) and 43.2% Sb(V) (2.9% RSD, n = 3) as percent of total Sb were detected in the examined soil sample using online ID. Using the above described methodology we found that there was no reduction of Sb(V) to Sb(III) during sample preparation or species separation. While about 9.3% of extractable Sb (4.6% of total) was converted from Sb(III) to Sb(V) during the extraction step, no conversion during HPLC separation step was observed. By compensating for Sb(III) transformation during the sample preparation step;the extractable Sb(III) and Sb(V) as percent of total Sb yielded 10.6% and 38.7%, respectively.展开更多
The classical cancer stem cell(CSCs)theory proposed the existence of a rare but constant subpopulation of CSCs.In this model cancer cells are organized hierarchically and are responsible for tumor resistance and tumor...The classical cancer stem cell(CSCs)theory proposed the existence of a rare but constant subpopulation of CSCs.In this model cancer cells are organized hierarchically and are responsible for tumor resistance and tumor relapse.Thus,eliminating CSCs will eventually lead to cure of cancer.This simplistic model has been challenged by experimental data.In 2010 we proposed a novel and controversial alternative model of CSC biology(the Stemness Phenotype Model,SPM).The SPM proposed a non-hierarchical model of cancer biology in which there is no specific subpopulation of CSCs in tumors.Instead,cancer cells are highly plastic in term of stemness and CSCs and non-CSCs can interconvert into each other depending on the microenvironment.This model predicts the existence of cancer cells ranging from a pure CSC phenotype to pure non-CSC phenotype and that survival of a single cell can originate a new tumor.During the past 10 years,a plethora of experimental evidence in a variety of cancer types has shown that cancer cells are indeed extremely plastic and able to interconvert into cells with different stemness phenotype.In this review we will(1)briefly describe the cumulative evidence from our laboratory and others supporting the SPM;(2)the implications of the SPM in translational oncology;and(3)discuss potential strategies to develop more effective therapeutic regimens for cancer treatment.展开更多
Diabetes mellitus(DM)has emerged as a serious public health concern,due to the high morbidity and mortality resulted from its complications,such as diabetic nephropathy,diabetic cardiovascular complication,and diabeti...Diabetes mellitus(DM)has emerged as a serious public health concern,due to the high morbidity and mortality resulted from its complications,such as diabetic nephropathy,diabetic cardiovascular complication,and diabetic neuropathy,etc.In this study,we investigated the beneficial effects of sepia ink melanin(SIM)on hyperglycaemia and the restoration of diabetic symptoms in streptozotocin(STZ)-induced diabetic model mice.At first,the normal experimental mice were performed with intraperitoneal injection of STZ(40 mg(kg BW)^(−1))(BW,body weight)to attain diabetes and then were treated with different concentrations of SIM(120,240 and 480 mg(kg BW)^(−1))for four weeks.After treatment,significant decrease in gluconeogenesis were determined,accompanied by a notable increase in both glycolysis and oxidative enzyme activities in SIM-treated groups,such as liver marker enzymes in the serum and key antioxidant enzymes in liver.qPCR results revealed the transcriptional alterations in SIM-treated groups.SIM exposure increased the expression levels of several genes related to insulin transduction and PI3K/Akt pathway,including PI3K,Akt,Irs-2,and InsR.Meanwhile,expression levels of Dicarbonyl/l-xylulose reductase(Dcxr)and UDP-glucose dehydrogenase(Ugdh),which are in-volved in pentose-glucuronate interconversion pathway,were also elevated in SIM-treated groups.Furthermore,histological observation results indicated that nuclear deformation and organelle dissolution were improved,thus could enhance the liver function.These results demonstrated that SIM can be effective in ameliorating diabetic symptoms and improving disease management for diabetic patients.展开更多
Thermoelectric(TE)materials can effectively achieve direct energy interconversions between heat and electrical energy(Seebeck,Peltier,and Thomson effects),showing wide applications in harvesting waste or low-grade hea...Thermoelectric(TE)materials can effectively achieve direct energy interconversions between heat and electrical energy(Seebeck,Peltier,and Thomson effects),showing wide applications in harvesting waste or low-grade heat,local cooling and sensing[1].展开更多
Given its high gravimetric energy density and status as a clean fuel when derived from renewables,hydrogen(H2)is considered a premier candidate for energy storage;however,its low volumetric density limits its broader ...Given its high gravimetric energy density and status as a clean fuel when derived from renewables,hydrogen(H2)is considered a premier candidate for energy storage;however,its low volumetric density limits its broader application.Chemical storage through the reversible incorporation of H2 into chemical bonds offers a promising solution to its low volumetric density,circumventing subpar energy densities and substantial infrastructure investments associated with physical storage methods.Metal hydrides are promising candidates for chemical storage because of their high gravimetric capacity and tunability through nanostructuring and alloying.Moreover,metal hydride/H2 interconversion may be interfaced with electrochemistry,which offers potential solutions to some of the challenges associated with traditional thermochemical platforms.In this Perspective,we describe anticipated challenges associated with electrochemically mediated metal hydride/H2 interconversion,including thermodynamic efficiencies of metal hydride formation,sluggish kinetics,and electrode passivation.Additionally,we propose potential solutions to these problems through the design of molecular mediators that may control factors such as metal hydride solubility,particle morphology,and hydride affinity.Realization of an electrochemically mediated metal hydride/H_(2) interconversion platform introduces new tools to address challenges associated with hydrogen storage platforms and contributes toward the development of room-temperature hydrogen storage platforms.展开更多
MicroRNAs (miRNAs) are a class of ～22 nt long endogenous non-coding RNAs that play important regulatory roles in diverse organisms. Up to now, little is known about the evolutionary properties of these crucial regula...MicroRNAs (miRNAs) are a class of ～22 nt long endogenous non-coding RNAs that play important regulatory roles in diverse organisms. Up to now, little is known about the evolutionary properties of these crucial regulators. Most miRNAs were thought to be phylogenetically conserved, but recently, a number of poorly-conserved miRNAs have been reported and miRNA innovation is shown to be an ongoing process. In this work, through the characterization of an miRNA super family, we studied the evolutionary patterns of miRNAs in vertebrates. Recently generated miRNAs seem to evolve rapidly during a certain period following their emergence. Multiple lineage-specific expansions were observed. Homolgous premiRNAs may produce mature products from the opposite stem arms following tandem duplications, which may have important contribution to miRNA innovation. Our observations of miRNAs' complicated evolutionary patterns support the notion that these key regulatory molecules may play very active roles in evolution.展开更多
Quantum coherence,emerging from the"superposition"of quantum states,is widely used in various information processing tasks.Recently,the resource theory of multilevel quantum coherence is attracting substanti...Quantum coherence,emerging from the"superposition"of quantum states,is widely used in various information processing tasks.Recently,the resource theory of multilevel quantum coherence is attracting substantial attention.In this paper,we mainly study the transformations of resource pure states via free operations in the theoretical framework for multilevel coherence.We prove that any two multilevel coherent resource pure states can be interconverted with a nonzero probability via a completely positive and trace non-increasing k-coherence-preserving map.Meanwhile,we present the condition of the interconversions of two multilevel coherent resource pure states under k-coherence-preserving operations.In addition,we obtain that in the resource-theoretic framework of multilevel coherence,no resource state is isolated,that is,given a multilevel coherent pure state|ψ>,there exists another multilevel coherent pure state|Φ>and a k-coherence-preserving operation∧k,such that∧k(|Φ>)=|ψ>.展开更多
Lead halide perovskite nanomaterials are among the forefront of developing materials for energy harvesting and light-emitting applications.Their unique defect tolerance,high photoluminescent quantum yields,and vast sy...Lead halide perovskite nanomaterials are among the forefront of developing materials for energy harvesting and light-emitting applications.Their unique defect tolerance,high photoluminescent quantum yields,and vast synthetic tunability make them attractive for many optoelectronic applications.In this review article,the broad synthetic toolbox of these materials is discussed,including how synthetic conditions can tune the optical properties and dimensionality of the resulting perovskite nanomaterial.Additionally,we discuss the brief history,current state,and bright future of these materials,in tune with their optoelectronic applications,namely in light-emitting diodes,lasing,photovoltaics,photon interconversion applications,and in photodetectors.展开更多
In the present work,a comparative study of analytical methods for the simultaneous and quantitative determination of trivalent and hexavalent chromium is presented.For the analysis by ion chromatography-inductively co...In the present work,a comparative study of analytical methods for the simultaneous and quantitative determination of trivalent and hexavalent chromium is presented.For the analysis by ion chromatography-inductively coupled plasma-mass spectrometry,two different columns were tested,as well as different mobile phases and different pH of the samples.The optimized analytical method permitted the separation of Cr(Ⅲ)and Cr(Ⅵ)using 75 mmol/L NH_(4)NO_(3)pH 3 as chromatographic eluent.The method was validated and applied to real samples,allowing the determination of both species simultaneously,even when there is a huge difference of concentration between Cr(Ⅲ)and Cr(Ⅵ).Limit of detection and limit of quantification for Cr(Ⅲ)were found to be 0.016 and 0.054μg/L(0.3 and 1.1μg/kg),respectively,and for Cr(Ⅵ)0.13 and 0.43μg/L(7 and 22μg/kg),respectively.Possible species interconversions were monitored through the use of chromium isotopic standards,which confirmed that the optimized methodology preserves chromium speciation during extraction and analysis.Fourier-transform ion cyclotron resonance-mass spectrometry permitted the structure elucidation of the complex formed during ethylenediaminetetraacetic acid extraction.展开更多
Although intermolecular aggregation-induced emission(AIE)has been extensively studied in nanocluster science,it remains challenging to activate AIE via intracluster aggregation(i.e.,the aggregation at the single-molec...Although intermolecular aggregation-induced emission(AIE)has been extensively studied in nanocluster science,it remains challenging to activate AIE via intracluster aggregation(i.e.,the aggregation at the single-molecular level).Here,an intracluster AIE system based on the Pt_(1)Ag_(24)(SR)18 nanocluster has been established.Specifically,triggered by the addition of free thiol ligands,the Ag_(2)(SR)_(3)surface motif structures of Pt_(1)Ag_(24)(SR)18 are aggregated to nanocluster poles.展开更多
基金supported by the Department of Education of Liaoning Province(Grant Nos.LJKZ1015,LJ2020005,LJKZZ20220120)the Natural Science Foundation of Liaoning Province(Grant Nos.2020-BS-234,2021-MS-317,2022-MS-372)the Program of Liaoning Bai Qian Wan Talents Program(Grant No.2021921096)。
文摘Conversion between different types of entangled states is an interesting problem in quantum mechanics.But research on the conversion between the Greenberger-Horne-Zeilinger(GHZ)state and Knill-Laflamme-Milburn(KLM)state in an atomic system has not been reported.In this paper,we propose a scheme to realize the interconversion(one-step)between the GHZ state and KLM state with Rydberg atoms.By utilizing Rydberg-mediated interactions,we simplify the system.By combining a Lie-transform-based pulse design,the evolution path is built up to realize interconversion of the GHZ state and KLM state.The numerical simulation result shows that the present scheme is robust against decoherence and operational imperfection.
基金Project supported by the Young Scientists Funds of the National Natural Science Foundation of China(Grant Nos.11404154 and 11304136)
文摘The relative conformer energies of glycine are evaluated by using a focal point analysis expressed as（HF→MP2→MP3→CCSD→CCSD（T））.The conformer abundances at various temperatures（298–500 K） are calculated based on the relative energies and Boltzmann statistical thermostatistical analysis with and without considering internal hindered rotations.A comparison between the available Raman spectrum and the electron momentum spectrum confirms that the influence of rigid-rotor hindered rotation on the conformational proportions of glycine is considerable,especially for the IIIp structure.The conformational interconversions are discussed.It is found that with increasing temperature,the mole fraction of IIn keeps constant and Ip structure can convert into IVn and IIIp,leading to the decrease in the weight of Ip and the increase in the weights of IVn and IIIp conformers,which is in accordance with experimental observations.
基金supported by the National Natural Science Fund for Distinguished Young Scholars of China(No.22025107)Shaanxi Fundamental Science Research Project for Chemistry&Biology(No.22JHZ003)。
文摘Poly-NHC-based organometallic assemblies 3-PF_(6),3-SbF_(6) and 3-OTf were obtained and verified by NMR spectroscopy,ESI mass spectrometry and single-crystal X-ray diffraction analyses.Controllable structural interconversion was observed between the poly-NHC-based organometallic assemblies and their self-aggregated dimers in solution affected by concentration,solvent and metal ion.1H NMR spectra of assembly 3-PF_(6) in CD_(3)CN at different concentrations demonstrated controllable structural interconversion,and ^(19)F NMR spectrum of assembly 3-PF_(6) at high concentration further evidenced the presence of the free hexafluorophosphate anion and encapsulated hexafluorophosphate anion for its two sets of signals.In addition,single-crystal X-ray diffraction analysis provided clear evidence that in the solid state,two assemblies 3-PF_(6) were vertically stuck,forming a self-aggregated dimer with an encapsulated hexafluorophosphate anion.Investigating the reversible structural interconversion is beneficial for revealing the intrinsic nature on the atom level and paving the way to design the stimuli-responsive functional system.
基金Supported by National Natural Science Foundation of China,No.82405314Horizontal Project of Dongzhimen Hospital,No.HX-DZM-202405+1 种基金Project of Beijing University of Chinese Medicine,No.DZMG-QNZX-24015Traditional Chinese Medicine Foundation of Xiamen,No.XWZY-2023-0616.
文摘BACKGROUND UDP-glucose 6-dehydrogenase(UGDH)is a key enzyme in glucuronic acid metabolism and acts as a key mediator in several cancer developmental signaling pathways.AIM To offer a more systematic and comprehensive elucidation of the involvement of UGDH in the onset and progression of various malignancies.METHODS The role of UGDH in cancer was investigated via public databases.The data were analyzed via various R packages and websites,including TISIDB,cBioPortal,STRING,Cytoscape,GSCALite,and CancerSEA.A rat hepatocellular carcinoma(HCC)model was established via the intraperitoneal injection of diethylnitrosamine.Hematoxylin-eosin staining,Masson staining,Ki67 and UGDH immunohistochemical staining,and ARG1 immunofluorescence staining of liver tissues were performed.Real-time quantitative PCR and Western blotting were used to detect UGDH expression.The UGDH gene was knocked down in Huh7 cells,and CCK8 and nude mouse tumor xenograft assays were performed.RESULTS High UGDH expression is associated with poor clinical outcomes in HCC,lung adenocarcinoma,lung squamous cell carcinoma,and sarcoma patients and is differentially expressed across molecular and immune subtypes.UGDH is primarily involved in the pentose and glucuronate interconversion pathway.Its expression is positively correlated with T helper,Tcm,and Th2 cells in most cancers.Moreover,experimental results demonstrated that UGDH expression is elevated in HCC tissues and that its downregulation inhibits HCC cell proliferation.CONCLUSION Our study revealed that UGDH could be a valuable prognostic biomarker and potential therapeutic target in many cancers,especially liver and lung cancer.UGDH could promote HCC cell proliferation,potentially by modulating the pentose and glucuronate interconversion pathways.
基金supported by the National Natural Science Foundation of China (21674022, 51703034)
文摘Orchestrating conflicting polymerization mechanisms in a single polymerization process through one external stimulus is a prerequisite to achieve in-situ selective synthesis of different monomers. Here we report an electrochemically controlled mechanism transformation that enables selective activation of living cationic or radical polymerization via an alternating voltage and dual electrocatalysts. Using identical mixed-monomer condition, a variety of desired block copolymer structures, including diblock, multiblock, random, and tapered copolymers can be obtained by simply varying the periods or phases of the alternating potential. Moreover, merging this electro-interconverted polymerization with a flow-chemistry technique can streamline preparation of functional polymer materials with complex multiblock structure. This study would offer a new vision on large-scale electrochemical synthesis of sequence-defined polymers.
基金supported by the National Basic Research Program of China(2011CB808600)the National Natural Science Foundation of China(21273102)
文摘The dynamic transformations of conformations and aromatic properties of [32]octaphyrins（1.0.1.0.1.0.1.0） through rotating the pyrrolic ring of the macrocycles are demonstrated by theoretical simulations in CH2Cl2 solution. Facile multistep isomeriza- tions involving antiaromatic-Htickel and aromatic-Mobius topologies were also predicted by density functional theory （DFT）. The understanding of changes in topologies and aromaticities of free-base expanded porphrins may provide useful information to build new macrocycles with unique properties.
文摘The interconversion between the two distinct isomers of methyl vinyl ether （MVE）, the formation of the primary ozonides from O3-initated reactions of MVE, the transformation between the primary ozonides, and the subsequent fragmentation were studied using quantum chemical methods at the BHandHLYP/6311＋＋G（d,p） level of theory for optimized geometries and frequency calculations and at the QCISD/631G（d,p） level for the single point energy calculations. The rate coefficients were calculated for the temperature range 280-440 K by using the canonical transition state theory （TST）. For ozone addition to MVE, there are two different possibilities discussed on the basis of two different possible orientations for ozone attack. The results of the theoretical study indicate that although the synperiplanar-MVE is 7.11 kJ/mol more stable than the antiperiplanar-MVE, the antiperiplanar-MVE plays a more important role in formation of the primary ozonides because the primary ozonides formed from the ozone addition antiperiplanar-MVE are more stable and the energy barriers corresponding to transition states are lower. The intereonversion between the primary ozonides formed from the ozone addition to antiperiplanar-MVE is the most accessible compared with the transformations between other primary ozonides. The cleavage of the primary ozonides mainly leads to the formation of the CH2OO, which is in agreement with the experimental estimates. The calculated overall rate constant for the ozone-initiated reactions is 4.8× 10^-17 cm^3/（molecule.s） at 298.15 K, which agrees with the experimental value for ethyl vinyl ether.
文摘A new method was developed in this work to account for inorganic Sb species interconversion during soil sample preparation and subsequent separation steps. The Sb(III) and Sb(V) concentrations at each investigated step in the analytical procedure were determined using species specific spikes (121Sb(III) with 81.18% and 123Sb(V) with 74.04% enrichment). The spiking of these enriched isotopes species solutions was done separately before soil sample extraction and before HPLC separation. Simply by subtracting the final concentration of each species done by on-line isotope dilution (ID) from its concentration at different stages of the analytical procedure done by species specific ID, the influence of each step on species transformation can be estimated. After optimization, the extraction procedure for inorganic Sb species 6% Sb(III) (1.3 RSD, n = 3) and 43.2% Sb(V) (2.9% RSD, n = 3) as percent of total Sb were detected in the examined soil sample using online ID. Using the above described methodology we found that there was no reduction of Sb(V) to Sb(III) during sample preparation or species separation. While about 9.3% of extractable Sb (4.6% of total) was converted from Sb(III) to Sb(V) during the extraction step, no conversion during HPLC separation step was observed. By compensating for Sb(III) transformation during the sample preparation step;the extractable Sb(III) and Sb(V) as percent of total Sb yielded 10.6% and 38.7%, respectively.
基金Supported by The Hampton University Regional Transdisciplinary Collaborative Center National Institute of Health(NIH),No.HU-180004(to Iyer AKV,Azad N and Yakisich JS)NIH-NIGMS,No.GM121287 and No.GM122655(to Azad N and Kulkarni Y,respectively).
文摘The classical cancer stem cell(CSCs)theory proposed the existence of a rare but constant subpopulation of CSCs.In this model cancer cells are organized hierarchically and are responsible for tumor resistance and tumor relapse.Thus,eliminating CSCs will eventually lead to cure of cancer.This simplistic model has been challenged by experimental data.In 2010 we proposed a novel and controversial alternative model of CSC biology(the Stemness Phenotype Model,SPM).The SPM proposed a non-hierarchical model of cancer biology in which there is no specific subpopulation of CSCs in tumors.Instead,cancer cells are highly plastic in term of stemness and CSCs and non-CSCs can interconvert into each other depending on the microenvironment.This model predicts the existence of cancer cells ranging from a pure CSC phenotype to pure non-CSC phenotype and that survival of a single cell can originate a new tumor.During the past 10 years,a plethora of experimental evidence in a variety of cancer types has shown that cancer cells are indeed extremely plastic and able to interconvert into cells with different stemness phenotype.In this review we will(1)briefly describe the cumulative evidence from our laboratory and others supporting the SPM;(2)the implications of the SPM in translational oncology;and(3)discuss potential strategies to develop more effective therapeutic regimens for cancer treatment.
基金supported by the Natural Science Foundation of Zhejiang Province(No.LY18C190006)sponsored by K.C.Wong Magna Fund in Ningbo University.
文摘Diabetes mellitus(DM)has emerged as a serious public health concern,due to the high morbidity and mortality resulted from its complications,such as diabetic nephropathy,diabetic cardiovascular complication,and diabetic neuropathy,etc.In this study,we investigated the beneficial effects of sepia ink melanin(SIM)on hyperglycaemia and the restoration of diabetic symptoms in streptozotocin(STZ)-induced diabetic model mice.At first,the normal experimental mice were performed with intraperitoneal injection of STZ(40 mg(kg BW)^(−1))(BW,body weight)to attain diabetes and then were treated with different concentrations of SIM(120,240 and 480 mg(kg BW)^(−1))for four weeks.After treatment,significant decrease in gluconeogenesis were determined,accompanied by a notable increase in both glycolysis and oxidative enzyme activities in SIM-treated groups,such as liver marker enzymes in the serum and key antioxidant enzymes in liver.qPCR results revealed the transcriptional alterations in SIM-treated groups.SIM exposure increased the expression levels of several genes related to insulin transduction and PI3K/Akt pathway,including PI3K,Akt,Irs-2,and InsR.Meanwhile,expression levels of Dicarbonyl/l-xylulose reductase(Dcxr)and UDP-glucose dehydrogenase(Ugdh),which are in-volved in pentose-glucuronate interconversion pathway,were also elevated in SIM-treated groups.Furthermore,histological observation results indicated that nuclear deformation and organelle dissolution were improved,thus could enhance the liver function.These results demonstrated that SIM can be effective in ameliorating diabetic symptoms and improving disease management for diabetic patients.
基金supported by the Guangdong Basic and Applied Basic Research Foundation(2025A1515012415).
文摘Thermoelectric(TE)materials can effectively achieve direct energy interconversions between heat and electrical energy(Seebeck,Peltier,and Thomson effects),showing wide applications in harvesting waste or low-grade heat,local cooling and sensing[1].
文摘Given its high gravimetric energy density and status as a clean fuel when derived from renewables,hydrogen(H2)is considered a premier candidate for energy storage;however,its low volumetric density limits its broader application.Chemical storage through the reversible incorporation of H2 into chemical bonds offers a promising solution to its low volumetric density,circumventing subpar energy densities and substantial infrastructure investments associated with physical storage methods.Metal hydrides are promising candidates for chemical storage because of their high gravimetric capacity and tunability through nanostructuring and alloying.Moreover,metal hydride/H2 interconversion may be interfaced with electrochemistry,which offers potential solutions to some of the challenges associated with traditional thermochemical platforms.In this Perspective,we describe anticipated challenges associated with electrochemically mediated metal hydride/H2 interconversion,including thermodynamic efficiencies of metal hydride formation,sluggish kinetics,and electrode passivation.Additionally,we propose potential solutions to these problems through the design of molecular mediators that may control factors such as metal hydride solubility,particle morphology,and hydride affinity.Realization of an electrochemically mediated metal hydride/H_(2) interconversion platform introduces new tools to address challenges associated with hydrogen storage platforms and contributes toward the development of room-temperature hydrogen storage platforms.
基金the National Natural Science Foundation of China (Grant Nos. 30625012, 60572086 and 60775002)National Basic Research Program of China (Grant No. 2004CB518605)
文摘MicroRNAs (miRNAs) are a class of ～22 nt long endogenous non-coding RNAs that play important regulatory roles in diverse organisms. Up to now, little is known about the evolutionary properties of these crucial regulators. Most miRNAs were thought to be phylogenetically conserved, but recently, a number of poorly-conserved miRNAs have been reported and miRNA innovation is shown to be an ongoing process. In this work, through the characterization of an miRNA super family, we studied the evolutionary patterns of miRNAs in vertebrates. Recently generated miRNAs seem to evolve rapidly during a certain period following their emergence. Multiple lineage-specific expansions were observed. Homolgous premiRNAs may produce mature products from the opposite stem arms following tandem duplications, which may have important contribution to miRNA innovation. Our observations of miRNAs' complicated evolutionary patterns support the notion that these key regulatory molecules may play very active roles in evolution.
基金supported by the National Natural Science Foundation of China(Grant No.12071110)the Hebei Natural Science Foundation of China(Grant Nos.A2020205014,and A2018205125)the Science and Technology Project of Hebei Education Department(Grant Nos.ZD2020167,and ZD2021066)。
文摘Quantum coherence,emerging from the"superposition"of quantum states,is widely used in various information processing tasks.Recently,the resource theory of multilevel quantum coherence is attracting substantial attention.In this paper,we mainly study the transformations of resource pure states via free operations in the theoretical framework for multilevel coherence.We prove that any two multilevel coherent resource pure states can be interconverted with a nonzero probability via a completely positive and trace non-increasing k-coherence-preserving map.Meanwhile,we present the condition of the interconversions of two multilevel coherent resource pure states under k-coherence-preserving operations.In addition,we obtain that in the resource-theoretic framework of multilevel coherence,no resource state is isolated,that is,given a multilevel coherent pure state|ψ>,there exists another multilevel coherent pure state|Φ>and a k-coherence-preserving operation∧k,such that∧k(|Φ>)=|ψ>.
文摘Lead halide perovskite nanomaterials are among the forefront of developing materials for energy harvesting and light-emitting applications.Their unique defect tolerance,high photoluminescent quantum yields,and vast synthetic tunability make them attractive for many optoelectronic applications.In this review article,the broad synthetic toolbox of these materials is discussed,including how synthetic conditions can tune the optical properties and dimensionality of the resulting perovskite nanomaterial.Additionally,we discuss the brief history,current state,and bright future of these materials,in tune with their optoelectronic applications,namely in light-emitting diodes,lasing,photovoltaics,photon interconversion applications,and in photodetectors.
基金supported by University of Rouen Normandy,INSA Rouen Normandy,the Centre National de la Recherche Scientifque(CNRS),European Regional Development Fund(ERDF HN0001343)Labex Syn-Org(ANR-11-LABX-0029)+1 种基金Carnot Institute I2C,the graduate school for research XL-Chem(ANR-18-EURE-0020 XL CHEM)Region Normandie,and Consejo Nacional de Ciencia y Tecnologia(CONACYT CVU 707668).
文摘In the present work,a comparative study of analytical methods for the simultaneous and quantitative determination of trivalent and hexavalent chromium is presented.For the analysis by ion chromatography-inductively coupled plasma-mass spectrometry,two different columns were tested,as well as different mobile phases and different pH of the samples.The optimized analytical method permitted the separation of Cr(Ⅲ)and Cr(Ⅵ)using 75 mmol/L NH_(4)NO_(3)pH 3 as chromatographic eluent.The method was validated and applied to real samples,allowing the determination of both species simultaneously,even when there is a huge difference of concentration between Cr(Ⅲ)and Cr(Ⅵ).Limit of detection and limit of quantification for Cr(Ⅲ)were found to be 0.016 and 0.054μg/L(0.3 and 1.1μg/kg),respectively,and for Cr(Ⅵ)0.13 and 0.43μg/L(7 and 22μg/kg),respectively.Possible species interconversions were monitored through the use of chromium isotopic standards,which confirmed that the optimized methodology preserves chromium speciation during extraction and analysis.Fourier-transform ion cyclotron resonance-mass spectrometry permitted the structure elucidation of the complex formed during ethylenediaminetetraacetic acid extraction.
基金support by the NSFC(nos.U1532141,21631001,21871001,and 21803001)the Ministry of Education,the Education Department of Anhui Province(no.KJ2017A010)Project 211 of Anhui University.
文摘Although intermolecular aggregation-induced emission(AIE)has been extensively studied in nanocluster science,it remains challenging to activate AIE via intracluster aggregation(i.e.,the aggregation at the single-molecular level).Here,an intracluster AIE system based on the Pt_(1)Ag_(24)(SR)18 nanocluster has been established.Specifically,triggered by the addition of free thiol ligands,the Ag_(2)(SR)_(3)surface motif structures of Pt_(1)Ag_(24)(SR)18 are aggregated to nanocluster poles.
