Alzheimer’s disease(AD)and other tauopathies are characterized by the accumulation of misfolded tau protein,which forms toxic oligomers that contribute to synaptic dysfunction and neuronal loss.Here,we briefly discus...Alzheimer’s disease(AD)and other tauopathies are characterized by the accumulation of misfolded tau protein,which forms toxic oligomers that contribute to synaptic dysfunction and neuronal loss.Here,we briefly discuss recent findings indicating that the cellular prion protein(PrPC)plays a critical role in mediating the synaptotoxic effects of tau oligomers(TauOs),offering new insights into disease pathogenesis and potential therapeutic strategies.展开更多
Catalysts are key for olefin polymerization reactions and are also ubiquitous in catalysis science.Multinuclear metal catalysts have witnessed enhanced performances in catalytic reactions relative to mononuclear catal...Catalysts are key for olefin polymerization reactions and are also ubiquitous in catalysis science.Multinuclear metal catalysts have witnessed enhanced performances in catalytic reactions relative to mononuclear catalysts,but which substantially involve multi-step,tedious,and difficult synthesis.Herein,this study reports an intriguing approach to construct multi-nuclear catalysts for the milestoneα-diimine nickel catalysts using an oligomeric strategy.A polymerizable norbornene unit is incorporated into theα-diimine ligand backbone,leading to the formation of the monomeric nickel catalyst Ni_(1)and its corresponding oligomeric nickel catalysts(Ni_(3)and Ni_(5))with varying degrees of polymerization(DP=3 and 5).Notably,the oligomeric catalyst Ni_(5)was facilely scaled up(50 g-level),showed enhanced thermal stability,exhibited 4.6 times higher activity,and yielded polyethylene elastomer with a 379%increased molecular weight in ethylene polymerization,compared to the monomeric catalyst Ni_(1).Catalytic performance enhancements of oligomeric catalysts were found to be DP-dependent.The kilogram-scale polyethylene,produced using Ni_(5)in a 20 L reactor,presented a highly branched all-hydrocarbon structure,which demonstrated typical elastic properties(tensile strength:4 MPa,elastic recovery:SR=72%)along with great processability(MFI=3.0 g/10 min),insulating characteristics(volume resistivity=2×10^(16)Ω/m),and hydrophobicity(water vapor permeability:0.03 g/m^(2)/day),suggesting potentially practical applications.展开更多
In Alzheimer’s disease,perturbations of glutamate neurotransmission lead to synaptic dysfunction and synapse loss.Several studies have used glutamate transport inhibitors to demonstrate that soluble oligomers of amyl...In Alzheimer’s disease,perturbations of glutamate neurotransmission lead to synaptic dysfunction and synapse loss.Several studies have used glutamate transport inhibitors to demonstrate that soluble oligomers of amyloid-βinduce synaptic dysfunction by interrupting glutamate uptake mediated by glutamate transporter 1,the major glutamate transporter in the brain.The cellular targets of the synaptic effects of soluble amyloid-βoligomers,including the nature of any interaction with glutamate transporter 1,remain ill-defined.We have generated a conditional glutamate transporter 1 knockout mouse to investigate cell-type specific functions of glutamate transporter 1.Field excitatory postsynaptic potentials were examined in the CA1 region of mouse hippocampal slices.We confirmed that hippocampal long-term potentiation impairment is induced by both soluble amyloid-β oligomers and glutamate uptake inhibitors.Amyloid-βoligomers,including those isolated directly from the cortex of patients with Alzheimer’s disease,failed to inhibit hippocampal long-term potentiation in neuronal glutamate transporter 1 but not astrocytic glutamate transporter 1 knockout mice.The masking or occlusion of the effect of soluble amyloid-β oligomers by knockout of glutamate transporter 1 in neurons suggests that the metabolic or signaling consequences of knockout of glutamate transporter 1 in neurons and amyloid-βoligomer inhibition of synaptic plasticity show epistasis and thus share a similar molecular pathway.To extend these observations,we tested the effects of other types of manipulation of glutamate homeostasis on synaptic plasticity and the pathophysiology of soluble amyloid-β oligomers.Ceftriaxone,which upregulates glutamate transporter 1 levels,among other effects,prevented the impairment of long-term potentiation by soluble amyloid-β oligomers.Collectively,our findings suggest that the effects of amyloid-βon synaptic function are highly dependent on glutamate reuptake homeostasis and that the disruption of synaptic function by soluble amyloid-β oligomers is mediated by pathways linked to neuronal,not astrocytic,glutamate transporter 1.The findings of this study highlight the translational potential of targeting neuronal glutamate transporter 1 to counteract amyloid-β-induced synaptic dysfunction in Alzheimer’s disease.By showing that glutamate transporter 1 upregulation(e.g.,via ceftriaxone)can prevent amyloid-β-related impairments,this research supports developing therapies aimed at modulating glutamate homeostasis to preserve synaptic function and combat cognitive decline in patients with Alzheimer’s disease.展开更多
The oligomerization of light olefins is considered a green production technology.Currently,the application of mordenite in isoamylene oligomerization faces two main challenges:low dimerization selectivity and poor sta...The oligomerization of light olefins is considered a green production technology.Currently,the application of mordenite in isoamylene oligomerization faces two main challenges:low dimerization selectivity and poor stability.In this work,a series of different SiO_(2)/Al_(2)O_(3) ratio mordenite are synthesized by utilizing hexamethyleneimine(HMI)as the organic structure directing agent,and it turns out that the rod-like zeolite with the ratio of SiO_(2)/Al_(2)O_(3)=14 exhibits the higher dimerization selectivity.The incorporation of TPOAC optimizes the pore structure and acid site distribution of the rod-like zeolite,which enables the samples to not only exhibit a conversion rate of isoamylene over 88.30% within 12 h,while maintaining good dimerization selectivity.These findings provide a promising approach for improving the efficiency and sustainability of olefin oligomerization processes.展开更多
Donor-acceptor(D-A)conjugated oligomers exhibit unique advantages in optoelectronic materials due to their well-defined molecular structures and ease of purification.However,current D-A oligomers incorporating electro...Donor-acceptor(D-A)conjugated oligomers exhibit unique advantages in optoelectronic materials due to their well-defined molecular structures and ease of purification.However,current D-A oligomers incorporating electron-deficient units like benzothiadiazole(BTz)and naphthobisthiadiazole(NTz)are largely restricted to linear configurations.In this study,two novel D-A conjugated oligomers(VG1 and VG2)with zigzag-shaped topological structures were designed and synthesized by integrating the electron-donating indacenodithiophene(IDT)unit with the previously developed strong electronwithdrawing triphenylenobisthiadiazole(TPTz)unit.Due to the unique V-shaped structure of TPTz unit,VG2 demonstrates a slightly reduced bandgap by 0.04 eV as the number of repeating units increases,while its light absorption coefficient is significantly enhanced.When applied to organic photovoltaic devices,the VG2:Y6-based device achieves a power conversion efficiency(PCE)of 2.56%,outperforming the VG1:Y6 system(2.37%).This improvement is attributed to the reduced radiative recombination losses below the bandgap and lower non-radiative energy losses in the VG2:Y6 device.This work offers a new strategy for modulating the topological structure of conjugated oligomers and their optoelectronic properties.展开更多
Near-infrared(NIR)theranostics have received considerable attention because of their advantages in precise diagnostic imaging and efficient simultaneous treatment and have achieved tremendous advancements in the last ...Near-infrared(NIR)theranostics have received considerable attention because of their advantages in precise diagnostic imaging and efficient simultaneous treatment and have achieved tremendous advancements in the last few years.However,their progress is severely restricted by the rarity of efficient second NIR(NIR-Ⅱ)responsive phototheranostic materials,especially in the NIR-Ⅱb region.Moreover,these materials often embarrass the quenching puzzle in the aggregative state,thus greatly reducing their theranostic performance.To overcome this limitation,we developed anti-quenching donor-acceptor-donor(D-AD)-conjugated oligomers with NIR-Ⅱb emission for high-performance NIR-Ⅱangiography and phototheranostics.Through multi-acceptor engineering,a series of multi-acceptor conjugated oligomer SU-n(n=1,2,and 5)with tunable acceptor ratios were synthesized,and their efficiency in anti-quenching NIR-Ⅱemission was demonstrated.When prepared into water-dispersed nanoparticles(NPs),SU-5 NPs exhibit bright NIR-Ⅱemission and dual phototherapy for photothermal therapy and photodynamic therapy simultaneously upon 808 nm light excitation.With these benefits,high-resolution whole-body and local angiography in vivo of SU-5 NPs were successfully realized in the NIR-Ⅱb window.Moreover,in vivo,theranostics experiments demonstrated the efficiency of SU-5 NPs in NIR-Ⅱimaging-guided complete tumor photoablation without any relapses with high biosafety.This work explores a practical multi-acceptor engineering strategy for developing anti-quenching theranostic materials,providing an efficient theranostic agent for efficient NIR-Ⅱb bioimaging and phototheranostics.展开更多
Nowadays,the utilization of renewable biomass as a substitute for petroleum-based feedstock in the synthesis of aerospace fuel has garnered significantattention.In this work,we use molecular sieve to catalyze the cont...Nowadays,the utilization of renewable biomass as a substitute for petroleum-based feedstock in the synthesis of aerospace fuel has garnered significantattention.In this work,we use molecular sieve to catalyze the controllable oligomerization of lignocellulose platform molecule furfuryl alcohol,which is prone to polymerize and generate furfuryl alcohol resin and other macromolecular substances.In order to reduce the formation of macromolecule polymers and enhance the yield of oligomers within the C9—C15 range,the reactive extraction strategy was implemented.Utilizing a low polar solvent,increasing the extraction phase content,employing a hydrophilic and weakly acidic molecular sieve are all beneficialfor enhancing the yield of the target products.Finally,under the optimal conditions,the conversion of furfuryl alcohol reaches 84.7%and the yield of the target products is improved from 10%—15%to 41.4%.After hydrodeoxygenation,a liquid fuel with paraffinas the main component was obtained.Moreover,the effect of substituents on the polymerization activity of furan derivatives was compared,the alkyl side chains as substituents can enhance both reactant activity and yield of target products.This study presents a viable approach for the efficientsynthesis of aviation fuel directly from bio-based furfuryl alcohol.展开更多
Alzheimer's disease(AD),the most prevalent form of dementia,disproportionately affects the elderly population.While aging is widely recognized as a major risk factor for AD,the precise mechanisms by which aging co...Alzheimer's disease(AD),the most prevalent form of dementia,disproportionately affects the elderly population.While aging is widely recognized as a major risk factor for AD,the precise mechanisms by which aging contributes to the pathogenesis of AD remain poorly understood.In our previous work,the neuropathological changes in the brains of aged cynomolgus monkeys(≥18 years old)following parenchymal cerebral injection of amyloid-β oligomers(AβOs)have been characterized.Here,we extend our investigation to middle-aged cynomolgus monkeys(≤15 years old)to establish an AD model.Surprisingly,immunohistochemical analysis reveals no detectable AD-related pathology in the brains of middle-aged monkeys,even after AβOs injection.In a comprehensive pathological analysis of 38 monkeys,we observe that the amyloid-β(Aβ)burden increases significantly with advancing age.Notably,the density of Aβ plaques is markedly higher in the ventral regions compared with the dorsal regions of aged monkey brains.Furthermore,we demonstrate that tau phosphorylation coincides with the accumulation of extensive Aβplaques and exhibits a positive correlation with Aβ burden in aged monkeys.Collectively,these findings underscore the critical role of the aged brain in providing the necessary conditions for AβO-induced AD pathologies in cynomolgus monkeys.展开更多
Direct viscosification of CO_(2) offers promising alternative for mobility control and reduction in residual brine saturation,thus to improve the CO_(2) trapping in saline aquifers.Hydrocarbon oligomers,recognized for...Direct viscosification of CO_(2) offers promising alternative for mobility control and reduction in residual brine saturation,thus to improve the CO_(2) trapping in saline aquifers.Hydrocarbon oligomers,recognized for their exceptional properties,are considered as one of the most promising viscosifiers in displacement of brine-saturated porous media.However,the molecular-level mechanisms governing the solubility and viscosification of hydrocarbon oligomers in scCO_(2) remain poorly understood.In this study,we employ coarse-grained molecular models to advance our understanding in the effects of molecular structure of hydrocarbon oligomers on their solubility in scCO_(2).The coarse-grained models of five hydrocarbon oligomers with different numbers of methyl-branch(n-C32,P1D-2,P1D-3,P1D-6 and squalane)are established to investigate their effects on solubilization in scCO_(2).We demonstrate that the number of methyl groups has a monotonic correlation with the solubility of hydrocarbon oligomers when the molecular weights of oligomers are comparable.The radial distribution function reveals nC32,P1D and squalane are uniformly dispersed with separation distances of approximately 1.0–2.0 nm.The interaction energy between hydrocarbon oligomers and CO_(2) shows that the number of methylbranch in hydrocarbon oligomers can directly influence their solubility in scCO_(2).Molecular simulation results demonstrate that the interaction distances between the methyl-branch and CO_(2) are smaller than those of other molecular fragments.There are approximately 20%more CO_(2) molecules interacting with methyl-branch than with other parts.This work sets the stage for our future molecular dynamics study in viscosification by hydrocarbon oligomers with different branching length and interfacial phenomena in multiphase systems.展开更多
Abnormal accumulation of collagen fibrils is a hallmark feature of oral submucous fibrosis(OSF).However,the precise characteristics and underlying mechanisms remain unclear,impeding the advancement of potential therap...Abnormal accumulation of collagen fibrils is a hallmark feature of oral submucous fibrosis(OSF).However,the precise characteristics and underlying mechanisms remain unclear,impeding the advancement of potential therapeutic approaches.Here,we observed that collagen Ⅰ,the main component of the extracellular matrix,first accumulated in the lamina propria and subsequently in the submucosa of OSF specimens as the disease progressed.Using RNA-seq and Immunofluorescence in OSF specimens,we screened the cartilage oligomeric matrix protein(COMP)responsible for the abnormal collagen accumulation.Genetic COMP deficiency reduced arecoline-stimulated collagen I deposition significantly in vivo.In comparison,both COMP and collagen Ⅰ were upregulated under arecoline stimulation in wild-type mice.Human oral buccal mucosal fibroblasts(hBMFs)also exhibited increased secretion of COMP and collagen I after stimulation in vitro.COMP knockdown in hBMFs downregulates arecoline-stimulated collagen Ⅰ secretion.We further demonstrated that hBMFs present heterogeneous responses to arecoline stimulation,of which COMP-positive fibroblasts secrete more collagen Ⅰ.Since COMP is a molecular bridge with Fibril-associated collagens with Interrupted Triple helices(FACIT)in the collagen network,we further screened and identified collagen XIV,a FACIT member,co-localizing with both COMP and collagen Ⅰ.Collagen XIV expression increased under arecoline stimulation in wild-type mice,whereas it was hardly expressed in the Comp^(-/-) mice,even with under stimulation.In summary,we found that COMP may mediates abnormal collagen Ⅰ deposition by functions with collagen XIV during the progression of OSF,suggesting its potential to be targeted in treating OSF.展开更多
AIM： To examine genetic variation of nucleotide oligomerization domain 1 （NOD/） and NOD2, their respective influences on Crohn＇s disease phenotype and gene-gene interactions. METHODS： （ND1＋32656＊1） NOD1 polym...AIM： To examine genetic variation of nucleotide oligomerization domain 1 （NOD/） and NOD2, their respective influences on Crohn＇s disease phenotype and gene-gene interactions. METHODS： （ND1＋32656＊1） NOD1 polymorphism and SNPS, SNP12 and SNP13 of NOD2 were analyzed in 97 patients and 50 controls. NOD2 variants were determined by reaction restriction fragment length polymorphism analysis. NOD1 genotyping and NOD2 variant confirmation were performed by specific amplification and sequencing. RESULTS： The distribution of NOD1 polymorphism in patients was different from controls （P = 0.045） and not altered by existence of NOD2 mutations. In this cohort, 30.92% patients and 6% controls carried at least one NOD2 variant （P 〈 0.001） with R702W being the most frequent variant. Presence of at least one NOD2 mutation was inversely associated with colon involvement （9.09% with colon vs 36.4% with ileal or ileocolonic involvement, P = 0.04） and indicative of risk of penetrating disease （52.63% with penetrating vs 25.64% with non-penetrating or stricturing behavior, P = 0.02）. L1007finsC and double NOD2 mutation conferred the highest risk for severity of disease （26.3% with penetrating disease vs 3.8% with non-penetrating or stricturing behavior presented L1007finsC, P = 0.01 and 21.0% with penetrating disease vs 2.5% with non-penentrating or stricturing behavior carried double NOD2 mutation, P = 0.007）. Exclusion of patients with NOD2 mutations from phenotype/NODl-genotype analysis revealed higher prevalence of ＊1＊1 genotype in groups of younger age at onset and colonic location.CONCLUSION： This study suggests population differences in the inheritance of risk NOD1 polymorphism and NOD2 mutations. Although no interaction between NOD1-NOD2 was noticed, a relationship between disease location and Nod-like receptor molecules was established.展开更多
BrФnsted-acidic zeolite and zeotype materials are potential catalysts for the conversion of ethene to higher alkenes. In this study, two materials with AFI structure but different acid strength, H-SAPO-5 and H-SSZ-24...BrФnsted-acidic zeolite and zeotype materials are potential catalysts for the conversion of ethene to higher alkenes. In this study, two materials with AFI structure but different acid strength, H-SAPO-5 and H-SSZ-24, were subject to studies of ethene, cis-2-butene and ethene-butene mixture conversion under conditions where C3-C5 alkene formation is thermodynamically favoured over higher hydrocarbons(673-823 K, 1 atm). Ethene and cis-2-butene partial pressures were varied in the range 9-60 and 0.9-8.1 kPa, respectively, and contact times were varied in the range 3.78-756 and 0.573-76.4 s.μmol H+/cm^3 over H-SAPO-5 and H-SSZ-24, respectively. Less than 1% conversion of ethene and less than 10% conversion of butene was obtained in the range of conditions used for elucidation of rate parameters. The ethene conversion rates were more than an order of magnitude higher over the more acidic H-SSZ-24 than over H-SAPO-5(6.5 vs. 0.3 mmol/mol H+.s at 748 K, Pethene = 33 kP a), with corresponding lower reaction order in ethene(1.5 vs. 2.0 at 673 K) and lower apparent activation energy(52 vs. 80 kJ/mol at 698-823 K). Propene selectivity was substantially higher over H-SSZ-24 than over H-SAPO-5(68% vs. 36% at 0.5% ethene conversion). A similar difference in apparent reaction rates was observed for cis-2-butene conversion over the two catalysts, and for co-feeds of ethene and cis-2-butene. However, the cis-2-butene conversion to C3-C5 alkenes was found to be severely influenced by thermodynamic limitations, impeding a detailed kinetic analysis, and leading predominantly to isobutene formation at the highest temperatures.展开更多
Among the inherent drawbacks of conducting polymers are the limited processibility, uneven polydispersity inmolecular weigh and the existence of structure defects, which become the obstacles for many electronic, optic...Among the inherent drawbacks of conducting polymers are the limited processibility, uneven polydispersity inmolecular weigh and the existence of structure defects, which become the obstacles for many electronic, optical andbiological applications that demand the materials to have well-defined structures and high chemical purity. To solve theseproblems, our research in the last decade or so has focused on the synthesis of electroactive oligomers of well-definedstructures, controllable molecular weighs, narrow or uniform polydispersity. We have developed a general strategy for thesynthesis of such oligomers based on the theory of non-classical or reactivation chain polymerization. The aniline oligomerswith minimum 4 nitrogen atoms and 3 phenylene rings exhibit similar characteristic redox behavior and electroactivity aspolyaniline. Electronic conductivity of the oligomers of 7 or 8 aniline units approaches that of polyaniline. Solubility of theoligomers is much improved over that of conventional polyaniline. Various functional groups can be introduced into theoligomers either by proper selection of starting materials or by post-synthesis modifications via common organic reactions.The functionalized oligomers undergo further polymerizations to afford a variety of new electroactive materials, includingpolyamides, polyimides, polyureas, polyurethanes, polyacrylamides and epoxy polymers. Numerous potential applications,particularly as anticorrosion materials, are discussed for the oligomers and their polymeric derivatives.展开更多
The photo-physical properties of oligo（fluorene-vinylene） functionalized anthracene linear oligomers （An-OFVn （n=1-4）） have been systemically investigated through experimental and theoretical methods. The steady...The photo-physical properties of oligo（fluorene-vinylene） functionalized anthracene linear oligomers （An-OFVn （n=1-4）） have been systemically investigated through experimental and theoretical methods. The steady-state spectral measurement shows that the increasing of fluorene-vinylene （FV） group could lead to the red shift of absorption spectra and restrain the excimer formation between oligomers. Quantum chemical calculations exhibit that the energy levels of HOMO, LUMO, and the band gap gradually converge to a constant in accompany with the increasing of FV unit. Meanwhile, the electronic cloud which distributes on the branch arms, also gradually enhances and makes the absorption spectral shape of oligomers become similar to that of branch arms step by step. The time-resolved fluorescence tests exhibits that the lifetime of excimer emission would be almost invariable after the number of FV group in oligomer is ≥2. In nonlinear optical test, the two-photon photoluminescence efficiency and two-photon absorption cross-section will both gradually enhance and be close to an extremum after the number of FV unit is equal to 4. These results will provide a guideline for the design of novel photo-electronic materials.展开更多
Background Coronary artery calcification(CAC)is common in end-stage renal disease(ESRD)patients,and the extent of CAC is closely related to cardiovascular outcomes in ESRD patients.Cartilage oligomeric matrix protein(...Background Coronary artery calcification(CAC)is common in end-stage renal disease(ESRD)patients,and the extent of CAC is closely related to cardiovascular outcomes in ESRD patients.Cartilage oligomeric matrix protein(COMP),as a component of the vascular matrix,has been found to be an inhibitor of arterial calcification in basic studies.However,there is no clinical research on the correlation between COMP and CAC in maintenance hemodialysis(MHD)patients.The aim of this study was to explore the relationship between serum COMP levels and CAC and cardiovascular events in MHD patients.Methods Serum COMP levels were compared between 54 MHD patients and 66 healthy people.MHD patients were then divided into three groups according to the tertiles of the concentration of COMP level and were followed up for major adverse cardiac events(MACEs),which were defined as a combined end point of new onset angina pectoris,nonfatal myocardial infarction,heart failure,coronary artery revascularization,hospitalization due to angina pectoris and all-cause deaths.The CAC score was calculated based on computed tomography scans.Results The serum COMP level in MHD patients was significantly higher than that in the general population[984.23(248.43-1902.61)ng/mL vs.219.01(97.26-821.92)ng/mL,P<0.01].Serum COMP levels were positively correlated with CAC(r=0.313,P=0.021)and serum parathyroid hormone in MHD patients(r=0.359,P<0.01).Linear regression suggested that after adjusting for age,fasting blood glucose(Glu)and glycosylated hemoglobin(HbAlc),CAC score was an independent predictor in the final model for COMP level(β=0.424,t=3.130,P<0.01).The receiver operating characteristic(ROC)curve showed that COMP≥994 mg/mL had 68.0%sensitivity and 72.4%specificity for the prediction of severe CAC[area under the curve(AUC):0.674,P=0.030,95%CI:0.526-0.882].After a median follow-up of 16 months(8-24 months),there was no difference in the incidence rate of MACEs between the upper,middle and lower serum COMP groups.Conclusions Our study found that MHD patients have higher levels of circulating COMP than controls.The serum COMP level is positively correlated with CAC score and could be used as a biomarker of severe CAC in MHD patients.However,there is no obvious correlation between serum COMP levels and the incidence of cardiovascular events.展开更多
The death of retinal ganglion cells is a hallmark of many optic neurodegenerative diseases such as glaucoma and retinopathy. Oxidative stress is one of the major reasons to cause the cell death. Oligomeric proanthocya...The death of retinal ganglion cells is a hallmark of many optic neurodegenerative diseases such as glaucoma and retinopathy. Oxidative stress is one of the major reasons to cause the cell death. Oligomeric proanthocyanidin has many health beneficial effects including antioxidative and neuro- protective actions. Here we tested whether oligomeric proanthocyanidin may protect retinal gan- glion cells against oxidative stress induced-apoptosis in vitro. Retinal ganglion cells were treated with hydrogen peroxide with or without oligomeric proanthocyanidin. 3-（4,5-Dimethylthiazol-2-yl）- 2,5-diphenyltetrazolium bromide （MTT） assay showed that treating retinal ganglion cell line RGC-5 cells with 20 pmol/L oligomeric proanthocyanidin significantly decreased the hydrogen peroxide （H202） induced death. Results of flow cytometry and Hoechst staining demonstrated that the death of RGC-5 cells was mainly caused by cell apoptosis. We further found that expression of pro-apoptotic Bax and caspase-3 were significantly decreased while anti-apoptotic Bcl-2 was greatly increased in H202 damaged RGC-5 cells with oligomeric proanthocyanidin by western blot assay. Furthermore, in retinal explant culture, the number of surviving retinal ganglion cells in H202-damaged retinal ganglion cells with oligomeric proanthocyanidin was significantly increased. Our studies thus demonstrate that oligomeric proanthocyanidin can protect oxidative stress-injured retinal ganglion cells by inhibiting apoptotic process.展开更多
The oligomerization of ethylene in FCC dry gas over HZSM-5 catalyst with different Si/A12 ratios was studied. The effect of acid density of catalyst on the oligomerization of ethylene was discussed. By increasing the ...The oligomerization of ethylene in FCC dry gas over HZSM-5 catalyst with different Si/A12 ratios was studied. The effect of acid density of catalyst on the oligomerization of ethylene was discussed. By increasing the acid density of catalyst, ethylene conversion showed a linear increase, while the yields of olefins decreased when the acid density of catalyst exceeded 0.14mmolNH3/g owing to a promotion of hydrogen transfer reaction. Through comparing the average distance between acid sites on catalyst with kinetic diameters of olefins, it was found that the dimerization of ethylene was not restrained by the sparse distribution of acid sites, while the hydrogen transfer reaction of C3 and C4 olefins was limited. On these bases, a conclusion is proposed that the dimerization of ethylene proceeded via Eley-Rideal mechanism, while the hydrogen transfer reaction of C3 and C4 olefins followed the Langmuir-Hinshelwood mechanism.展开更多
Background Cartilage oligomeric matrix protein （COMP） is mainly found in the skeletal system and vascular smooth muscle cells. Recent researches showed that it had a protective function on blood vessels and could al...Background Cartilage oligomeric matrix protein （COMP） is mainly found in the skeletal system and vascular smooth muscle cells. Recent researches showed that it had a protective function on blood vessels and could also inhibit vascular calcification. We investigated the serum COMPs in coronary heart disease （CHD） patients, and the relationship between serum COMP and the calcification of coronary artery. Methods A total of 233 consecutive chest pain patients who first underwent coronary angiography followed by multi-slice computed to- mography （MSCT） within six months were recruited and divided into two groups according to the coronary angiography luminal diameter narrowing percentages： CHD group （diameter narrowing 〉 50%, n = 194） and control group （diameter narrowing 〈 50%, n = 39）. The Gen- sini score, Syntax score and coronary artery calcium score （CACs） were calculated. The serum COMP level was determined using ELISA. Results The levels of COMP were significantly higher in the CHD group than in the control group 155.7 （124.5-194.5） ng/mL vs. 128.4 （113.0-159.9） ng/mL, P = 0.019. There were no correlation between COMP, Gensini score, Syntax score, severity of coronary stenosis and the number of coronary artery with stenosis 〉 50%. The serum COMP was correlated with age （r = 0.294, P 〈 0.001）, fasting glucose （r = 0.163, P = 0.015）, HbAlc （r = 0.194, P = 0.015） and CACs （r = 0.137, P = 0.037）. Stepwise linear regression analysis showed that COMP level and age were independent predictors of CACs in the CHD patients （fl = 0.402, t = 2.612, P = 0.015; fl = 0.472, t = 3.077, P = 0.005）. Performance of COMP for predicting CHD was shown as area under curve （AUC）： 0.632, 95% CI： 0.549-0.715 and upper tertile CACs was AUC： 0.602, 95% CI： 0.5264）.678 in receiver operating characteristic （ROC） curve analysis. Conclusion Calcification of coronary artery was an independent predictor of serum COMPs.展开更多
AIM: Oligomeric proanthocyanidins (OPC), natural polyphenolic compounds found in plants, are known to have antioxidant and anti-cancer effects. We investigated whether the anti-cancer effects of the OPC are induced by...AIM: Oligomeric proanthocyanidins (OPC), natural polyphenolic compounds found in plants, are known to have antioxidant and anti-cancer effects. We investigated whether the anti-cancer effects of the OPC are induced by apoptosis on human colorectal cancer cell line, SNU-C4.METHODS: Colorectal cancer cell line, SNU-C4 was cultured in RPMI 1640 medium supplemented with 10% fetal bovine serum. The cytotoxic effect of OPC was assessed by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenylt-etrazolium bromide (MTT) assay. To find out the apoptotic cell death, 4, 6-diamidino-2-phenylindole (DAPI) staining,terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) assay, reverse transcriptionpolymerase chain reaction (RT-PCR), and caspase-3 enzyme assay were performed.RESULTS: In this study, cytotoxic effect of OPC on SNUC4 cells appeared in a dose-dependent manner. OPC treatment (100 μg/mL) revealed typical morphological apoptotic features. Additionally OPC treatment (100 μg/mL)increased level of BAX and CASPASE-3, and decreased level of BCL-2 mRNA expression. Caspase-3 enzyme activity was also significantly increased by treatment of OPC (100 μg/mL) compared with control.CONCLUSION: These data indicate that OPC caused cell death by apoptosis through caspase pathways on human colorectal cancer cell line, SNU-C4.展开更多
Two neutral five-membered pyridine-imine palladium complexes with the bulky dibenzhydryl（CH（Ph）2） substituted aniline were synthesized and fully characterized by nuclear magnetic resonance（NMR） and X-ray crystal...Two neutral five-membered pyridine-imine palladium complexes with the bulky dibenzhydryl（CH（Ph）2） substituted aniline were synthesized and fully characterized by nuclear magnetic resonance（NMR） and X-ray crystal diffraction. Well-defined cationic palladium complexes were further obtained by treatment of chloromethylpalladium complexes with sodium tetrakis（3,5-bis（trifluoromethyl）phenyl）borate（NaBArF） in CH3CN. Cationic palladium complexes were capable of catalyzing ethylene oligomerization without any cocatalysts. The influences of catalyst structure, reaction temperature, and ethylene pressure on ethylene oligomerization were studied in detail. The introduction of bulky benzhydryl（CH（Ph）2） on the ortho position of the aniline moiety enhanced catalytic activity, thermal stability of the catalyst, and molecular weight of the obtained products. Highly branched oligomers with molecular weights of 600-800 g/mol and narrow polydispersities（1.03-1.12） were produced.展开更多
基金supported by the Italian Ministry of Health grant RF-2021-12372337(to GF and CB).
文摘Alzheimer’s disease(AD)and other tauopathies are characterized by the accumulation of misfolded tau protein,which forms toxic oligomers that contribute to synaptic dysfunction and neuronal loss.Here,we briefly discuss recent findings indicating that the cellular prion protein(PrPC)plays a critical role in mediating the synaptotoxic effects of tau oligomers(TauOs),offering new insights into disease pathogenesis and potential therapeutic strategies.
基金financial support from the National Natural Science Foundation of China(Nos.22401274,U23B6011)the Jilin Provincial Science and Technology Department Program(No.20250102070JC)。
文摘Catalysts are key for olefin polymerization reactions and are also ubiquitous in catalysis science.Multinuclear metal catalysts have witnessed enhanced performances in catalytic reactions relative to mononuclear catalysts,but which substantially involve multi-step,tedious,and difficult synthesis.Herein,this study reports an intriguing approach to construct multi-nuclear catalysts for the milestoneα-diimine nickel catalysts using an oligomeric strategy.A polymerizable norbornene unit is incorporated into theα-diimine ligand backbone,leading to the formation of the monomeric nickel catalyst Ni_(1)and its corresponding oligomeric nickel catalysts(Ni_(3)and Ni_(5))with varying degrees of polymerization(DP=3 and 5).Notably,the oligomeric catalyst Ni_(5)was facilely scaled up(50 g-level),showed enhanced thermal stability,exhibited 4.6 times higher activity,and yielded polyethylene elastomer with a 379%increased molecular weight in ethylene polymerization,compared to the monomeric catalyst Ni_(1).Catalytic performance enhancements of oligomeric catalysts were found to be DP-dependent.The kilogram-scale polyethylene,produced using Ni_(5)in a 20 L reactor,presented a highly branched all-hydrocarbon structure,which demonstrated typical elastic properties(tensile strength:4 MPa,elastic recovery:SR=72%)along with great processability(MFI=3.0 g/10 min),insulating characteristics(volume resistivity=2×10^(16)Ω/m),and hydrophobicity(water vapor permeability:0.03 g/m^(2)/day),suggesting potentially practical applications.
文摘In Alzheimer’s disease,perturbations of glutamate neurotransmission lead to synaptic dysfunction and synapse loss.Several studies have used glutamate transport inhibitors to demonstrate that soluble oligomers of amyloid-βinduce synaptic dysfunction by interrupting glutamate uptake mediated by glutamate transporter 1,the major glutamate transporter in the brain.The cellular targets of the synaptic effects of soluble amyloid-βoligomers,including the nature of any interaction with glutamate transporter 1,remain ill-defined.We have generated a conditional glutamate transporter 1 knockout mouse to investigate cell-type specific functions of glutamate transporter 1.Field excitatory postsynaptic potentials were examined in the CA1 region of mouse hippocampal slices.We confirmed that hippocampal long-term potentiation impairment is induced by both soluble amyloid-β oligomers and glutamate uptake inhibitors.Amyloid-βoligomers,including those isolated directly from the cortex of patients with Alzheimer’s disease,failed to inhibit hippocampal long-term potentiation in neuronal glutamate transporter 1 but not astrocytic glutamate transporter 1 knockout mice.The masking or occlusion of the effect of soluble amyloid-β oligomers by knockout of glutamate transporter 1 in neurons suggests that the metabolic or signaling consequences of knockout of glutamate transporter 1 in neurons and amyloid-βoligomer inhibition of synaptic plasticity show epistasis and thus share a similar molecular pathway.To extend these observations,we tested the effects of other types of manipulation of glutamate homeostasis on synaptic plasticity and the pathophysiology of soluble amyloid-β oligomers.Ceftriaxone,which upregulates glutamate transporter 1 levels,among other effects,prevented the impairment of long-term potentiation by soluble amyloid-β oligomers.Collectively,our findings suggest that the effects of amyloid-βon synaptic function are highly dependent on glutamate reuptake homeostasis and that the disruption of synaptic function by soluble amyloid-β oligomers is mediated by pathways linked to neuronal,not astrocytic,glutamate transporter 1.The findings of this study highlight the translational potential of targeting neuronal glutamate transporter 1 to counteract amyloid-β-induced synaptic dysfunction in Alzheimer’s disease.By showing that glutamate transporter 1 upregulation(e.g.,via ceftriaxone)can prevent amyloid-β-related impairments,this research supports developing therapies aimed at modulating glutamate homeostasis to preserve synaptic function and combat cognitive decline in patients with Alzheimer’s disease.
基金supported by the National Natural Science Foundation of China(21776505)。
文摘The oligomerization of light olefins is considered a green production technology.Currently,the application of mordenite in isoamylene oligomerization faces two main challenges:low dimerization selectivity and poor stability.In this work,a series of different SiO_(2)/Al_(2)O_(3) ratio mordenite are synthesized by utilizing hexamethyleneimine(HMI)as the organic structure directing agent,and it turns out that the rod-like zeolite with the ratio of SiO_(2)/Al_(2)O_(3)=14 exhibits the higher dimerization selectivity.The incorporation of TPOAC optimizes the pore structure and acid site distribution of the rod-like zeolite,which enables the samples to not only exhibit a conversion rate of isoamylene over 88.30% within 12 h,while maintaining good dimerization selectivity.These findings provide a promising approach for improving the efficiency and sustainability of olefin oligomerization processes.
文摘Donor-acceptor(D-A)conjugated oligomers exhibit unique advantages in optoelectronic materials due to their well-defined molecular structures and ease of purification.However,current D-A oligomers incorporating electron-deficient units like benzothiadiazole(BTz)and naphthobisthiadiazole(NTz)are largely restricted to linear configurations.In this study,two novel D-A conjugated oligomers(VG1 and VG2)with zigzag-shaped topological structures were designed and synthesized by integrating the electron-donating indacenodithiophene(IDT)unit with the previously developed strong electronwithdrawing triphenylenobisthiadiazole(TPTz)unit.Due to the unique V-shaped structure of TPTz unit,VG2 demonstrates a slightly reduced bandgap by 0.04 eV as the number of repeating units increases,while its light absorption coefficient is significantly enhanced.When applied to organic photovoltaic devices,the VG2:Y6-based device achieves a power conversion efficiency(PCE)of 2.56%,outperforming the VG1:Y6 system(2.37%).This improvement is attributed to the reduced radiative recombination losses below the bandgap and lower non-radiative energy losses in the VG2:Y6 device.This work offers a new strategy for modulating the topological structure of conjugated oligomers and their optoelectronic properties.
基金supported by the National Natural Science Foundation of China(Nos.52173135,22207024)the Natural Science Foundation of Jiangsu Province(No.BK20231523)+5 种基金Jiangsu Specially Appointed Professorship,Leading Talents of Innovation and Entrepreneurship of Gusu(No.ZXL2022496)the Suzhou Science and Technology Program(No.SKY2022039)funded by the China Postdoctoral Science Foundation(Nos.2022M712305,2023M742536)the Jiangsu Funding Program for Excellent Postdoctoral Talent(No.2023ZB011)the project funded by the Priority Academic Program Development(PAPD)of Jiangsu Higher Education InstitutionsSuzhou International Joint Laboratory for Diagnosis and Treatment of Brain Diseases。
文摘Near-infrared(NIR)theranostics have received considerable attention because of their advantages in precise diagnostic imaging and efficient simultaneous treatment and have achieved tremendous advancements in the last few years.However,their progress is severely restricted by the rarity of efficient second NIR(NIR-Ⅱ)responsive phototheranostic materials,especially in the NIR-Ⅱb region.Moreover,these materials often embarrass the quenching puzzle in the aggregative state,thus greatly reducing their theranostic performance.To overcome this limitation,we developed anti-quenching donor-acceptor-donor(D-AD)-conjugated oligomers with NIR-Ⅱb emission for high-performance NIR-Ⅱangiography and phototheranostics.Through multi-acceptor engineering,a series of multi-acceptor conjugated oligomer SU-n(n=1,2,and 5)with tunable acceptor ratios were synthesized,and their efficiency in anti-quenching NIR-Ⅱemission was demonstrated.When prepared into water-dispersed nanoparticles(NPs),SU-5 NPs exhibit bright NIR-Ⅱemission and dual phototherapy for photothermal therapy and photodynamic therapy simultaneously upon 808 nm light excitation.With these benefits,high-resolution whole-body and local angiography in vivo of SU-5 NPs were successfully realized in the NIR-Ⅱb window.Moreover,in vivo,theranostics experiments demonstrated the efficiency of SU-5 NPs in NIR-Ⅱimaging-guided complete tumor photoablation without any relapses with high biosafety.This work explores a practical multi-acceptor engineering strategy for developing anti-quenching theranostic materials,providing an efficient theranostic agent for efficient NIR-Ⅱb bioimaging and phototheranostics.
基金support from the National Key Research and Development Program of China(2023YFB4103000)the Joint Fund of Ministry of Education for Equipment Pre-research(8091B03052304)the Haihe Laboratory of Sustainable Chemical Transformations for financialsupport.
文摘Nowadays,the utilization of renewable biomass as a substitute for petroleum-based feedstock in the synthesis of aerospace fuel has garnered significantattention.In this work,we use molecular sieve to catalyze the controllable oligomerization of lignocellulose platform molecule furfuryl alcohol,which is prone to polymerize and generate furfuryl alcohol resin and other macromolecular substances.In order to reduce the formation of macromolecule polymers and enhance the yield of oligomers within the C9—C15 range,the reactive extraction strategy was implemented.Utilizing a low polar solvent,increasing the extraction phase content,employing a hydrophilic and weakly acidic molecular sieve are all beneficialfor enhancing the yield of the target products.Finally,under the optimal conditions,the conversion of furfuryl alcohol reaches 84.7%and the yield of the target products is improved from 10%—15%to 41.4%.After hydrodeoxygenation,a liquid fuel with paraffinas the main component was obtained.Moreover,the effect of substituents on the polymerization activity of furan derivatives was compared,the alkyl side chains as substituents can enhance both reactant activity and yield of target products.This study presents a viable approach for the efficientsynthesis of aviation fuel directly from bio-based furfuryl alcohol.
基金supported in part by the National Key Basic Research and Development Program of China(2019YFA0801402,2018YFA0107200,2018YFA0801402,2018YFA0800100)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA16020501 and XDA16020404)the National Natural Science Foundation of China(32130030,31900454,32470866,32471010,32100800)。
文摘Alzheimer's disease(AD),the most prevalent form of dementia,disproportionately affects the elderly population.While aging is widely recognized as a major risk factor for AD,the precise mechanisms by which aging contributes to the pathogenesis of AD remain poorly understood.In our previous work,the neuropathological changes in the brains of aged cynomolgus monkeys(≥18 years old)following parenchymal cerebral injection of amyloid-β oligomers(AβOs)have been characterized.Here,we extend our investigation to middle-aged cynomolgus monkeys(≤15 years old)to establish an AD model.Surprisingly,immunohistochemical analysis reveals no detectable AD-related pathology in the brains of middle-aged monkeys,even after AβOs injection.In a comprehensive pathological analysis of 38 monkeys,we observe that the amyloid-β(Aβ)burden increases significantly with advancing age.Notably,the density of Aβ plaques is markedly higher in the ventral regions compared with the dorsal regions of aged monkey brains.Furthermore,we demonstrate that tau phosphorylation coincides with the accumulation of extensive Aβplaques and exhibits a positive correlation with Aβ burden in aged monkeys.Collectively,these findings underscore the critical role of the aged brain in providing the necessary conditions for AβO-induced AD pathologies in cynomolgus monkeys.
基金the financial support and funding provided by the National Natural Science Foundation of China(Youth Talent Program,Key Special Project,Grant No.52341401 and Distinguished Scholar Program with a Grant No.52425402)High-level Start-up Funding from Peking University Shenzhen Graduate School,Shenzhen Science and Technology Foundation(Grant No.JCYJ20230807120807016)+2 种基金High-level Startup Funding from China University of Petroleum-Beijing(Grant No.2462024YJRC033)the China Postdoctoral Science(CPS)Foundation(Certificate No.2024M750106)the Postdoctoral Fellowship Program of CPS(Grant No.GZC20240051)。
文摘Direct viscosification of CO_(2) offers promising alternative for mobility control and reduction in residual brine saturation,thus to improve the CO_(2) trapping in saline aquifers.Hydrocarbon oligomers,recognized for their exceptional properties,are considered as one of the most promising viscosifiers in displacement of brine-saturated porous media.However,the molecular-level mechanisms governing the solubility and viscosification of hydrocarbon oligomers in scCO_(2) remain poorly understood.In this study,we employ coarse-grained molecular models to advance our understanding in the effects of molecular structure of hydrocarbon oligomers on their solubility in scCO_(2).The coarse-grained models of five hydrocarbon oligomers with different numbers of methyl-branch(n-C32,P1D-2,P1D-3,P1D-6 and squalane)are established to investigate their effects on solubilization in scCO_(2).We demonstrate that the number of methyl groups has a monotonic correlation with the solubility of hydrocarbon oligomers when the molecular weights of oligomers are comparable.The radial distribution function reveals nC32,P1D and squalane are uniformly dispersed with separation distances of approximately 1.0–2.0 nm.The interaction energy between hydrocarbon oligomers and CO_(2) shows that the number of methylbranch in hydrocarbon oligomers can directly influence their solubility in scCO_(2).Molecular simulation results demonstrate that the interaction distances between the methyl-branch and CO_(2) are smaller than those of other molecular fragments.There are approximately 20%more CO_(2) molecules interacting with methyl-branch than with other parts.This work sets the stage for our future molecular dynamics study in viscosification by hydrocarbon oligomers with different branching length and interfacial phenomena in multiphase systems.
基金supported by the National Natural Science Foundation of China grant(81974150).
文摘Abnormal accumulation of collagen fibrils is a hallmark feature of oral submucous fibrosis(OSF).However,the precise characteristics and underlying mechanisms remain unclear,impeding the advancement of potential therapeutic approaches.Here,we observed that collagen Ⅰ,the main component of the extracellular matrix,first accumulated in the lamina propria and subsequently in the submucosa of OSF specimens as the disease progressed.Using RNA-seq and Immunofluorescence in OSF specimens,we screened the cartilage oligomeric matrix protein(COMP)responsible for the abnormal collagen accumulation.Genetic COMP deficiency reduced arecoline-stimulated collagen I deposition significantly in vivo.In comparison,both COMP and collagen Ⅰ were upregulated under arecoline stimulation in wild-type mice.Human oral buccal mucosal fibroblasts(hBMFs)also exhibited increased secretion of COMP and collagen I after stimulation in vitro.COMP knockdown in hBMFs downregulates arecoline-stimulated collagen Ⅰ secretion.We further demonstrated that hBMFs present heterogeneous responses to arecoline stimulation,of which COMP-positive fibroblasts secrete more collagen Ⅰ.Since COMP is a molecular bridge with Fibril-associated collagens with Interrupted Triple helices(FACIT)in the collagen network,we further screened and identified collagen XIV,a FACIT member,co-localizing with both COMP and collagen Ⅰ.Collagen XIV expression increased under arecoline stimulation in wild-type mice,whereas it was hardly expressed in the Comp^(-/-) mice,even with under stimulation.In summary,we found that COMP may mediates abnormal collagen Ⅰ deposition by functions with collagen XIV during the progression of OSF,suggesting its potential to be targeted in treating OSF.
基金Supported by a grant of Ministerio Educacion y Ciencia (BFU 2006-15063)E.C.is participant of the Program "Contratos de apoyo a la Investigacion del Sistema Nacional de Salud". S.V. was supported by "Fondo Investigaciones Sanitarias" and participant of the Program for Stabilization of Investigators of "Direccio d’ Estrategia i Coordinacio del Departament Salut de la Generalitat de Catalunya"
文摘AIM： To examine genetic variation of nucleotide oligomerization domain 1 （NOD/） and NOD2, their respective influences on Crohn＇s disease phenotype and gene-gene interactions. METHODS： （ND1＋32656＊1） NOD1 polymorphism and SNPS, SNP12 and SNP13 of NOD2 were analyzed in 97 patients and 50 controls. NOD2 variants were determined by reaction restriction fragment length polymorphism analysis. NOD1 genotyping and NOD2 variant confirmation were performed by specific amplification and sequencing. RESULTS： The distribution of NOD1 polymorphism in patients was different from controls （P = 0.045） and not altered by existence of NOD2 mutations. In this cohort, 30.92% patients and 6% controls carried at least one NOD2 variant （P 〈 0.001） with R702W being the most frequent variant. Presence of at least one NOD2 mutation was inversely associated with colon involvement （9.09% with colon vs 36.4% with ileal or ileocolonic involvement, P = 0.04） and indicative of risk of penetrating disease （52.63% with penetrating vs 25.64% with non-penetrating or stricturing behavior, P = 0.02）. L1007finsC and double NOD2 mutation conferred the highest risk for severity of disease （26.3% with penetrating disease vs 3.8% with non-penetrating or stricturing behavior presented L1007finsC, P = 0.01 and 21.0% with penetrating disease vs 2.5% with non-penentrating or stricturing behavior carried double NOD2 mutation, P = 0.007）. Exclusion of patients with NOD2 mutations from phenotype/NODl-genotype analysis revealed higher prevalence of ＊1＊1 genotype in groups of younger age at onset and colonic location.CONCLUSION： This study suggests population differences in the inheritance of risk NOD1 polymorphism and NOD2 mutations. Although no interaction between NOD1-NOD2 was noticed, a relationship between disease location and Nod-like receptor molecules was established.
文摘BrФnsted-acidic zeolite and zeotype materials are potential catalysts for the conversion of ethene to higher alkenes. In this study, two materials with AFI structure but different acid strength, H-SAPO-5 and H-SSZ-24, were subject to studies of ethene, cis-2-butene and ethene-butene mixture conversion under conditions where C3-C5 alkene formation is thermodynamically favoured over higher hydrocarbons(673-823 K, 1 atm). Ethene and cis-2-butene partial pressures were varied in the range 9-60 and 0.9-8.1 kPa, respectively, and contact times were varied in the range 3.78-756 and 0.573-76.4 s.μmol H+/cm^3 over H-SAPO-5 and H-SSZ-24, respectively. Less than 1% conversion of ethene and less than 10% conversion of butene was obtained in the range of conditions used for elucidation of rate parameters. The ethene conversion rates were more than an order of magnitude higher over the more acidic H-SSZ-24 than over H-SAPO-5(6.5 vs. 0.3 mmol/mol H+.s at 748 K, Pethene = 33 kP a), with corresponding lower reaction order in ethene(1.5 vs. 2.0 at 673 K) and lower apparent activation energy(52 vs. 80 kJ/mol at 698-823 K). Propene selectivity was substantially higher over H-SSZ-24 than over H-SAPO-5(68% vs. 36% at 0.5% ethene conversion). A similar difference in apparent reaction rates was observed for cis-2-butene conversion over the two catalysts, and for co-feeds of ethene and cis-2-butene. However, the cis-2-butene conversion to C3-C5 alkenes was found to be severely influenced by thermodynamic limitations, impeding a detailed kinetic analysis, and leading predominantly to isobutene formation at the highest temperatures.
文摘Among the inherent drawbacks of conducting polymers are the limited processibility, uneven polydispersity inmolecular weigh and the existence of structure defects, which become the obstacles for many electronic, optical andbiological applications that demand the materials to have well-defined structures and high chemical purity. To solve theseproblems, our research in the last decade or so has focused on the synthesis of electroactive oligomers of well-definedstructures, controllable molecular weighs, narrow or uniform polydispersity. We have developed a general strategy for thesynthesis of such oligomers based on the theory of non-classical or reactivation chain polymerization. The aniline oligomerswith minimum 4 nitrogen atoms and 3 phenylene rings exhibit similar characteristic redox behavior and electroactivity aspolyaniline. Electronic conductivity of the oligomers of 7 or 8 aniline units approaches that of polyaniline. Solubility of theoligomers is much improved over that of conventional polyaniline. Various functional groups can be introduced into theoligomers either by proper selection of starting materials or by post-synthesis modifications via common organic reactions.The functionalized oligomers undergo further polymerizations to afford a variety of new electroactive materials, includingpolyamides, polyimides, polyureas, polyurethanes, polyacrylamides and epoxy polymers. Numerous potential applications,particularly as anticorrosion materials, are discussed for the oligomers and their polymeric derivatives.
文摘The photo-physical properties of oligo（fluorene-vinylene） functionalized anthracene linear oligomers （An-OFVn （n=1-4）） have been systemically investigated through experimental and theoretical methods. The steady-state spectral measurement shows that the increasing of fluorene-vinylene （FV） group could lead to the red shift of absorption spectra and restrain the excimer formation between oligomers. Quantum chemical calculations exhibit that the energy levels of HOMO, LUMO, and the band gap gradually converge to a constant in accompany with the increasing of FV unit. Meanwhile, the electronic cloud which distributes on the branch arms, also gradually enhances and makes the absorption spectral shape of oligomers become similar to that of branch arms step by step. The time-resolved fluorescence tests exhibits that the lifetime of excimer emission would be almost invariable after the number of FV group in oligomer is ≥2. In nonlinear optical test, the two-photon photoluminescence efficiency and two-photon absorption cross-section will both gradually enhance and be close to an extremum after the number of FV unit is equal to 4. These results will provide a guideline for the design of novel photo-electronic materials.
基金supported by the National Natural Science Foundation of China(81400262)the Backbone Fund of Peking University Third Hospital(Y72497-04)
文摘Background Coronary artery calcification(CAC)is common in end-stage renal disease(ESRD)patients,and the extent of CAC is closely related to cardiovascular outcomes in ESRD patients.Cartilage oligomeric matrix protein(COMP),as a component of the vascular matrix,has been found to be an inhibitor of arterial calcification in basic studies.However,there is no clinical research on the correlation between COMP and CAC in maintenance hemodialysis(MHD)patients.The aim of this study was to explore the relationship between serum COMP levels and CAC and cardiovascular events in MHD patients.Methods Serum COMP levels were compared between 54 MHD patients and 66 healthy people.MHD patients were then divided into three groups according to the tertiles of the concentration of COMP level and were followed up for major adverse cardiac events(MACEs),which were defined as a combined end point of new onset angina pectoris,nonfatal myocardial infarction,heart failure,coronary artery revascularization,hospitalization due to angina pectoris and all-cause deaths.The CAC score was calculated based on computed tomography scans.Results The serum COMP level in MHD patients was significantly higher than that in the general population[984.23(248.43-1902.61)ng/mL vs.219.01(97.26-821.92)ng/mL,P<0.01].Serum COMP levels were positively correlated with CAC(r=0.313,P=0.021)and serum parathyroid hormone in MHD patients(r=0.359,P<0.01).Linear regression suggested that after adjusting for age,fasting blood glucose(Glu)and glycosylated hemoglobin(HbAlc),CAC score was an independent predictor in the final model for COMP level(β=0.424,t=3.130,P<0.01).The receiver operating characteristic(ROC)curve showed that COMP≥994 mg/mL had 68.0%sensitivity and 72.4%specificity for the prediction of severe CAC[area under the curve(AUC):0.674,P=0.030,95%CI:0.526-0.882].After a median follow-up of 16 months(8-24 months),there was no difference in the incidence rate of MACEs between the upper,middle and lower serum COMP groups.Conclusions Our study found that MHD patients have higher levels of circulating COMP than controls.The serum COMP level is positively correlated with CAC score and could be used as a biomarker of severe CAC in MHD patients.However,there is no obvious correlation between serum COMP levels and the incidence of cardiovascular events.
基金supported by grants from theNational Basic Research Program of China,No.973Program,2011CB707501the Natural Science Foundation of Guangdong Province,China,No.S2012010008874+1 种基金the Natural Science Foundation of Guangzhou,China,No.11BppZXaa2070006,D.X.Lthe National Natural Science Foundation of China,No.81100669
文摘The death of retinal ganglion cells is a hallmark of many optic neurodegenerative diseases such as glaucoma and retinopathy. Oxidative stress is one of the major reasons to cause the cell death. Oligomeric proanthocyanidin has many health beneficial effects including antioxidative and neuro- protective actions. Here we tested whether oligomeric proanthocyanidin may protect retinal gan- glion cells against oxidative stress induced-apoptosis in vitro. Retinal ganglion cells were treated with hydrogen peroxide with or without oligomeric proanthocyanidin. 3-（4,5-Dimethylthiazol-2-yl）- 2,5-diphenyltetrazolium bromide （MTT） assay showed that treating retinal ganglion cell line RGC-5 cells with 20 pmol/L oligomeric proanthocyanidin significantly decreased the hydrogen peroxide （H202） induced death. Results of flow cytometry and Hoechst staining demonstrated that the death of RGC-5 cells was mainly caused by cell apoptosis. We further found that expression of pro-apoptotic Bax and caspase-3 were significantly decreased while anti-apoptotic Bcl-2 was greatly increased in H202 damaged RGC-5 cells with oligomeric proanthocyanidin by western blot assay. Furthermore, in retinal explant culture, the number of surviving retinal ganglion cells in H202-damaged retinal ganglion cells with oligomeric proanthocyanidin was significantly increased. Our studies thus demonstrate that oligomeric proanthocyanidin can protect oxidative stress-injured retinal ganglion cells by inhibiting apoptotic process.
文摘The oligomerization of ethylene in FCC dry gas over HZSM-5 catalyst with different Si/A12 ratios was studied. The effect of acid density of catalyst on the oligomerization of ethylene was discussed. By increasing the acid density of catalyst, ethylene conversion showed a linear increase, while the yields of olefins decreased when the acid density of catalyst exceeded 0.14mmolNH3/g owing to a promotion of hydrogen transfer reaction. Through comparing the average distance between acid sites on catalyst with kinetic diameters of olefins, it was found that the dimerization of ethylene was not restrained by the sparse distribution of acid sites, while the hydrogen transfer reaction of C3 and C4 olefins was limited. On these bases, a conclusion is proposed that the dimerization of ethylene proceeded via Eley-Rideal mechanism, while the hydrogen transfer reaction of C3 and C4 olefins followed the Langmuir-Hinshelwood mechanism.
文摘Background Cartilage oligomeric matrix protein （COMP） is mainly found in the skeletal system and vascular smooth muscle cells. Recent researches showed that it had a protective function on blood vessels and could also inhibit vascular calcification. We investigated the serum COMPs in coronary heart disease （CHD） patients, and the relationship between serum COMP and the calcification of coronary artery. Methods A total of 233 consecutive chest pain patients who first underwent coronary angiography followed by multi-slice computed to- mography （MSCT） within six months were recruited and divided into two groups according to the coronary angiography luminal diameter narrowing percentages： CHD group （diameter narrowing 〉 50%, n = 194） and control group （diameter narrowing 〈 50%, n = 39）. The Gen- sini score, Syntax score and coronary artery calcium score （CACs） were calculated. The serum COMP level was determined using ELISA. Results The levels of COMP were significantly higher in the CHD group than in the control group 155.7 （124.5-194.5） ng/mL vs. 128.4 （113.0-159.9） ng/mL, P = 0.019. There were no correlation between COMP, Gensini score, Syntax score, severity of coronary stenosis and the number of coronary artery with stenosis 〉 50%. The serum COMP was correlated with age （r = 0.294, P 〈 0.001）, fasting glucose （r = 0.163, P = 0.015）, HbAlc （r = 0.194, P = 0.015） and CACs （r = 0.137, P = 0.037）. Stepwise linear regression analysis showed that COMP level and age were independent predictors of CACs in the CHD patients （fl = 0.402, t = 2.612, P = 0.015; fl = 0.472, t = 3.077, P = 0.005）. Performance of COMP for predicting CHD was shown as area under curve （AUC）： 0.632, 95% CI： 0.549-0.715 and upper tertile CACs was AUC： 0.602, 95% CI： 0.5264）.678 in receiver operating characteristic （ROC） curve analysis. Conclusion Calcification of coronary artery was an independent predictor of serum COMPs.
文摘AIM: Oligomeric proanthocyanidins (OPC), natural polyphenolic compounds found in plants, are known to have antioxidant and anti-cancer effects. We investigated whether the anti-cancer effects of the OPC are induced by apoptosis on human colorectal cancer cell line, SNU-C4.METHODS: Colorectal cancer cell line, SNU-C4 was cultured in RPMI 1640 medium supplemented with 10% fetal bovine serum. The cytotoxic effect of OPC was assessed by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenylt-etrazolium bromide (MTT) assay. To find out the apoptotic cell death, 4, 6-diamidino-2-phenylindole (DAPI) staining,terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) assay, reverse transcriptionpolymerase chain reaction (RT-PCR), and caspase-3 enzyme assay were performed.RESULTS: In this study, cytotoxic effect of OPC on SNUC4 cells appeared in a dose-dependent manner. OPC treatment (100 μg/mL) revealed typical morphological apoptotic features. Additionally OPC treatment (100 μg/mL)increased level of BAX and CASPASE-3, and decreased level of BCL-2 mRNA expression. Caspase-3 enzyme activity was also significantly increased by treatment of OPC (100 μg/mL) compared with control.CONCLUSION: These data indicate that OPC caused cell death by apoptosis through caspase pathways on human colorectal cancer cell line, SNU-C4.
基金financially supported by the National Natural Science Foundation of China (Nos. 21374134 and 21674130)the Natural Science Foundation of Guangdong Province (No. 2014A030313160)+1 种基金the Fundamental Research Funds for the Central Universities (No. 17lgjc02)PetroChina Innovation Foundation (No. 2017D-5007-0505)
文摘Two neutral five-membered pyridine-imine palladium complexes with the bulky dibenzhydryl（CH（Ph）2） substituted aniline were synthesized and fully characterized by nuclear magnetic resonance（NMR） and X-ray crystal diffraction. Well-defined cationic palladium complexes were further obtained by treatment of chloromethylpalladium complexes with sodium tetrakis（3,5-bis（trifluoromethyl）phenyl）borate（NaBArF） in CH3CN. Cationic palladium complexes were capable of catalyzing ethylene oligomerization without any cocatalysts. The influences of catalyst structure, reaction temperature, and ethylene pressure on ethylene oligomerization were studied in detail. The introduction of bulky benzhydryl（CH（Ph）2） on the ortho position of the aniline moiety enhanced catalytic activity, thermal stability of the catalyst, and molecular weight of the obtained products. Highly branched oligomers with molecular weights of 600-800 g/mol and narrow polydispersities（1.03-1.12） were produced.
