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
A series of Ni/ZSM-5 containing a small amount of Ni was prepared by an ion exchanged method.The impact of the n(SiO_(2))/n(Al_(2)O_(3))ratio on the catalytic activity was studied using the samples 0.09Ni/ZSM-5(60)and...A series of Ni/ZSM-5 containing a small amount of Ni was prepared by an ion exchanged method.The impact of the n(SiO_(2))/n(Al_(2)O_(3))ratio on the catalytic activity was studied using the samples 0.09Ni/ZSM-5(60)and 0.09Ni/ZSM-5(130).To determine the interaction between the Ni species and acid sites on the surface of the catalyst,the catalysts were characterized by N2 adsorption-desorption,X-ray diffraction(XRD),scanning electron microscopy(SEM),and UV-vis spectroscopy.The performance of the catalysts for the catalytic oligomerization of 1-hexene was investigated in detail.The nickel species were found to be uniformly distributed in all the catalysts.It was discovered that the oligomerization activity of the catalyst can be improved using Ni species;however,the contribution of Brønsted acids in oligomerization reactions is greater than that of Ni sites and Lewis acids.展开更多
BACKGROUND Gastric intestinal metaplasia(IM)is a precancerous lesion that is associated with an elevated risk of gastric carcinogenesis.Weiwei Decoction(WWD)is a promising traditional Chinese herbal formula widely emp...BACKGROUND Gastric intestinal metaplasia(IM)is a precancerous lesion that is associated with an elevated risk of gastric carcinogenesis.Weiwei Decoction(WWD)is a promising traditional Chinese herbal formula widely employed in clinical for treating IM.Previous studies suggested the potential involvement of the olfactomedin 4(OLFM4)/nucleotide-binding oligomerization domain 1(NOD1)/caudal-type homeobox gene 2(CDX2)signaling pathway in IM regulation.AIM To verify the regulation of the OLFM4/NOD1/CDX2 pathway in IM,specifically investigating WWD’s effectiveness on IM through this pathway.METHODS Immunohistochemistry for OLFM4,NOD1,and CDX2 was conducted on tissue microarray.GES-1 cells treated with chenodeoxycholic acid were utilized as IM cell models.OLFM4 short hairpin RNA(shRNA),NOD1 shRNA,and OLFM4 pcDNA were transfected to clarify the pathway regulatory relationships.Protein interactions were validated by coimmunoprecipitation.To explore WWD’s pharmacological actions,IM rat models were induced using N-methyl-N’-nitro-N-nitrosoguanidine followed by WWD gavage.Gastric cells were treated with WWD-medicated serum.Cytokines and chemokines content were assessed by enzyme-linked immunosorbent assay and quantitative reverse transcription polymerase chain reaction.RESULTS The OLFM4/NOD1/CDX2 axis was a characteristic of IM.OLFM4 exhibited direct binding and subsequent downregulation of NOD1,thereby sustaining the activation of CDX2 and promoting the progression of IM.WWD improved gastric mucosal histological lesions while suppressing intestinal markers KLF transcription factor 4,villin 1,and MUCIN 2 expression in IM rats.Regarding pharmacological actions,WWD suppressed OLFM4 and restored NOD1 expression,consequently reducing CDX2 at the mRNA and protein levels in IM rats.Parallel regulatory mechanisms were observed at the protein level in IM cells treated with WWD-medicated serum.Furthermore,WWD-medicated serum treatment strengthened OLFM4 and NOD1 interaction.In case of antiinflammatory,WWD restrained interleukin(IL)-6,interferon-gamma,IL-17,macrophage chemoattractant protein-1,macrophage inflammatory protein 1 alpha content in IM rat serum.WWD-medicated serum inhibited tumor necrosis factor alpha,IL-6,IL-8 transcriptions in IM cells.CONCLUSION The OLFM4/NOD1/CDX2 pathway is involved in the regulation of IM.WWD exerts its therapeutic efficacy on IM through the pathway,additionally attenuating the inflammatory response.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
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
The objective of this study is to explore the optimum composition of Y and ZSM-5 zeolites to develop novel catalysts for obtaining lower gasoline olefins content and higher propylene yield. Five composite zeolite cata...The objective of this study is to explore the optimum composition of Y and ZSM-5 zeolites to develop novel catalysts for obtaining lower gasoline olefins content and higher propylene yield. Five composite zeolite catalysts with varying Y zeolite/ZSM-5 zeolite ratios have been prepared in this work to investigate the synergy between the Y zeolite and ZSM-5 zeolite on the selectivity to protolytic cracking, β-scission, oligomerization, and hydrogen transfer reactions using a FCC naphtha feedstock at 480 ℃ in a confined fluidized bed reactor. Experimental results showed that the composite catalyst with a Y zeolite/ZSM-5 zeolite ratio of 1:4 had the highest protolytic cracking and β-scission ability, which was even higher than that of pure ZSM-5 catalyst. On the other hand, the catalyst with a Y zeolite/ZSM-5 zeolite ratio of 3:2 exhibited the strongest hydrogen transfer functionality while the pure Y zeolite based catalyst had the highest oligomerization ability. For all the catalysts tested, increasing conversion enhanced the selectivity to protolytic cracking and hydrogen transfer reactions but reduced the selectivity to β-scission reaction. However, no clear trend was identified for the selectivity to oligomerization when an increased conversion was experienced.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
Olefin oligomerization reaction catalyzed by new catalyst systems(a Bronsted‐acidic ionic liquid as the main catalyst and tricaprylylmethylammonium chloride as the co‐catalyst)has been investigat‐ed.The synthesized...Olefin oligomerization reaction catalyzed by new catalyst systems(a Bronsted‐acidic ionic liquid as the main catalyst and tricaprylylmethylammonium chloride as the co‐catalyst)has been investigat‐ed.The synthesized Bronsted acidic ionic liquids were characterized by Fourier transform infrared spectroscopy(FT‐IR),ultraviolet‐visible spectroscopy(UV),^(1)H nuclear magnetic resonance(NMR),and^13 C NMR to analyze their structures and acidities.The influence of different ionic liquids,ionic liquid loading,different co‐catalysts,catalyst ratios(mole ratio of ionic liquid to co‐catalyst),reac‐tion time,pressure,temperature,solvent,source of reactants,and the recycling of catalyst systems was studied.Among the synthesized ionic liquids,1‐(4‐sulfonic acid)butyl‐3‐hexylimidazolium hydrogen sulfate([HIMBs]HSO4)exhibited the best catalytic activity under the tested reaction con‐ditions.The conversion of isobutene and selectivity of trimers were 83.21%and 35.80%,respec‐tively,at the optimum reaction conditions.Furthermore,the catalyst system can be easily separated and reused;a feasible reaction mechanism is proposed on the basis of the distribution of experi‐mental products.展开更多
1-Decene was oligomerized over the supported AlCl3/γ-Al2O3 catalyst in a fixed-bed reactor. The effects of temperature and LHSV on oligomerization of 1-decene were investigated and the synthetic PAO was characterized...1-Decene was oligomerized over the supported AlCl3/γ-Al2O3 catalyst in a fixed-bed reactor. The effects of temperature and LHSV on oligomerization of 1-decene were investigated and the synthetic PAO was characterized with GC technique. Furthermore, the life of immobilized catalyst was tested and the mechanism of catalyst deactivation was discussed. The results showed that with an increasing temperature, the PAO yield increased and the kinematic viscosity of oil decreased. The GC results indicated that the synthesized PAO was a mixture consisting of dimers, trimers, tetramers and pentamers. The results of chloride content measurements and BET tests showed that catalyst deactivation could be mainly attributed to the loss of active components.展开更多
During cell division, chromosome segregation is orchestrated by the interaction of spindle microtubules with the centromere. A dramatic remodeling of interpolar microtubules into an organized central spindle between t...During cell division, chromosome segregation is orchestrated by the interaction of spindle microtubules with the centromere. A dramatic remodeling of interpolar microtubules into an organized central spindle between the separating chromatids is required for the initiation and execution ofcytokinesis. Central spindle organization requires mitotic kinesins, the chromosomal passenger protein complex, and microtubule bundling protein PRC 1. PRC 1 is phosphorylated by Cdc2 at Thr470 and Thr481 during mitosis. However, the functional relevance of PRC 1 phosphorylation at Thr470 has remained elusive. Here we show that expression of the non-phosphorylatable mutant PRC 1T470A but not the phospho-mimicking mutant PRC 1^T470E causes aberrant organization of the central spindle. Immunoprecipitation experiment indicates that both PRC 1^T470A and PRC 1^T470E mutant proteins associate with wild-type PRC 1, suggesting that phosphorylation of Thr470 does not alter PRC 1 self-association. In addition, in vitro co-sedimentation experiment showed that PRC 1 binds to microtubule independent of the phosphorylation state of Thr470. Gel-filtration experiment suggested that phosphorylation of Thr470 promotes oligomerization of PRC 1. Given the fact that prevention of the Thr470 phosphorylation inhibits PRC 1 oligomerization in vitro and causes an aberrant organization of central spindle in vivo, we propose that this phosphorylation-dependent PRC 1 oligomerization ensures that central spindle assembly occurs at the appropriate time in the cell cycle.展开更多
Nucleotide-binding oligomerization domain 1(NOD1) is an intracellular innate immune sensor for small molecules derived from bacterial cell components. NOD1 activation by its ligands leads to robust production of pro-i...Nucleotide-binding oligomerization domain 1(NOD1) is an intracellular innate immune sensor for small molecules derived from bacterial cell components. NOD1 activation by its ligands leads to robust production of pro-inflammatory cytokines and chemokines by innate immune cells, thereby mediating mucosal host defense systems against microbes. Chronic gastric infection due to Helicobacter pylori(H. pylori) causes various upper gastrointestinal diseases, including atrophic gastritis, peptic ulcers, and gastric cancer. It is now generally accepted that detection of H. pylori by NOD1 expressed in gastric epithelial cells plays an indispensable role in mucosal host defense systems against this organism. Recent studies have revealed the molecular mechanism by which NOD1 activation caused by H. pylori infection is involved in the development of chronic gastritis and gastric cancer. In this review, we have discussed and summarized how sensing of H. pylori by NOD1 mediates the prevention of chronic gastritis and gastric cancer.展开更多
AIM: To investigate the expression of nucleotide oligomerization domain 2 (NOD2) in the immortalized human corneal epithelial cell line (THCE), and its role in the innate immune response triggered by inactive Aspergil...AIM: To investigate the expression of nucleotide oligomerization domain 2 (NOD2) in the immortalized human corneal epithelial cell line (THCE), and its role in the innate immune response triggered by inactive Aspergillus fumigatus (Af) conidia. METHODS: The normal THCE cells were investigated as controls. After incubation with inactive Af conidia for 0.5, 2, 4, 6, and 8 hours, THCE cells were harvested, mRNA expression of NOD2 and receptor interacting protein 2 (RIP2) was detected by RT-PCR. Intracellular proteins including NOD2, NF-kappa B and proinflammatory cytokines such as TNF-alpha, IL-8, IL-6 in the cell supernatant were analyzed by ELISA. RESULTS: Our data indicate that NOD2 expressed in the normal THCE cells. After triggered by the inactive Af conidia, the expression of NOD2, RIP2 mRNA and the secretion of NOD2, NF-kappa B, TNF-alpha, IL-8, IL-6 both increased in a time-depended manner, and reached the peak point at 4, 6, 6, 4, 6, 6, 4 hours, respectively. And after pretreated with NOD2 neutralizing antibody, the expression of RIP2, NF-kappa B, TNF-alpha, IL-8 both decreased dramatically at the peak point, while the secretion of IL-6 changed little. CONCLUSION: The results of this study suggest that NOD2 exists and expresses in the THCE cells, and contributes to the innate immune responses triggered by inactive Afconidia by induction of proinflammatory cytokines such as TNF-alpha and IL-8 through the NF-kappa B pathway.展开更多
A series of nickel（II） α-diimine complexes with strong electron-withdrawing carboxyl groups, having reactive hydrogen atoms, were prepared and used as precatalysts for ethylene oligomerization and/or polymerization...A series of nickel（II） α-diimine complexes with strong electron-withdrawing carboxyl groups, having reactive hydrogen atoms, were prepared and used as precatalysts for ethylene oligomerization and/or polymerization. The influence of metal halides and ligand structure on the catalytic activity and properties of products was investigated. The results showed that nickel bromide was much more active than nickel chloride, and the substituents at the ortho-position of aryl ring had large influence on the properties of products. Therefore, the products ranging from liquid oligomers to polymers could be readily obtained by the variation of the substituents on the ligands and reaction conditions.展开更多
The chemoselectivities of PdCl2 and CuCl2-catalyzed oligomerization of 3, 3-dimethyl-butyne: 1, 3, 5-tri-tert-butylbenzene, 2, 2, 7, 7-tetramethyl-3, 6-dichloro-3, 5-octadiene and 2, 2, 7, 7- tetramethyl-3, 5-octadiyn...The chemoselectivities of PdCl2 and CuCl2-catalyzed oligomerization of 3, 3-dimethyl-butyne: 1, 3, 5-tri-tert-butylbenzene, 2, 2, 7, 7-tetramethyl-3, 6-dichloro-3, 5-octadiene and 2, 2, 7, 7- tetramethyl-3, 5-octadiyne were obtained, respectively, by regulating the polarity of the solvent.展开更多
The structure of Ni active sites supported on amorphous silica-alumina supports with different contents of Al_(2)O_(3)loadings in relation to their activities in ethylene oligomerization were investigated.Two kinds of...The structure of Ni active sites supported on amorphous silica-alumina supports with different contents of Al_(2)O_(3)loadings in relation to their activities in ethylene oligomerization were investigated.Two kinds of Ni sites were detected by in situ FTIR-CO and H_(2)-TPR experiments,that are Ni^(2+)cations as grafted on weak acidic silanols and Ni^(2+)cations at ion-exchange positions.The ethylene oligomerization activities of these Ni/ASA catalysts were found an ascending tendency as the Al_(2)O_(3)loading decreased,which could be attributed to the enriched concentration of Ni^(2+)species on acidic silanols with a weaker interaction with the amorphous silica-alumina support.These Ni^(2+)species were more easily to be evolved into Ni^(+)species,which has been identified to be the active sites of ethylene oligomerization.Thus,it seems reasonable to conclude that Ni^(2+)species grafted on acidic silanols were the precursors of active sites.展开更多
Novel Ni（II）-based acetyliminopyridine complexes 1b, 2b, 3b （1-3b）, which are synthesized from ligands 1a, 2a, 3a （1-3a） and [NiCl2（DME）], are suitable precursors for the catalysts that are necessary for ethyl...Novel Ni（II）-based acetyliminopyridine complexes 1b, 2b, 3b （1-3b）, which are synthesized from ligands 1a, 2a, 3a （1-3a） and [NiCl2（DME）], are suitable precursors for the catalysts that are necessary for ethylene oligomerization and polymerization reactions, activated by methylaluminoxane （MAO）. The MAO-treated 1-3b presents an active catalytic center, which may oligomerize and polymerize ethylene to produce linear α-olefins and polyethylene, respectively. The molecular weight distributions of oligomers that are obtained are in good agreement with the Schulz-Flory rules for oligomers〉C4. The activity of 3b-MAO complex is 6.3×10^7 g/（molNi.h） at 50 ℃. The activities and molecular weight distributions of oligomers show significant reliance on the structures of catalyst precursors.展开更多
Ethylene oligomerization using ZSM-5 zeolite was investigated to study the role of Bronsted acid sites in the formation of higher hydrocarbons. The oligomerization of olefins, dependent on the acidity of ZSM-5 zeolite...Ethylene oligomerization using ZSM-5 zeolite was investigated to study the role of Bronsted acid sites in the formation of higher hydrocarbons. The oligomerization of olefins, dependent on the acidity of ZSM-5 zeolite, is an important step in the conversion of natural gas to liquid fuels. The framework Si/Al ratio reflects the number of potential acid sites and the acid strength of the ZSM-5 catalyst. ZSM-5 with the mole ratio SiO2/Al2O3 equal to 30 was dealuminated for different periods of time according to the acidic ion-exchange method to produce ZSM-5 with various Si/Al ratios. The FT-IR analysis revealed that the integrated framework aluminum band, non-framework aluminum band, and silanol groups areas of the ZSM-5 zeolites decreased after being dealuminated. The performance of the dealuminated zeolite was tested for ethylene oligomerization. The results demonstrated that the dealumination of ZSM-5 led to higher ethylene conversion, but the gasoline selectivity was reduced compared to the performance of a ZSM-5 zeolite. The characterization results revealed the amount of aluminum in the zeolitic framework, the crystallinity of the ZSM-5 zeolite, and the Si/Al ratio affected the formation of Bronsted acid sites. The number of the Bronsted acid sites on the catalyst active sites is important in the olefin conversion to liquid hydrocarbons.展开更多
Several nickel complexes [N,N]NiBr_2, in which [N,N] indicates bidentatenitrogen-containing ligands (1: [N,N]=N-(2,6-diisopropylphenyl)pyridine-2-carboxaldimine(C_(18)H_(22)N_2); 2: N-(2,6-diisopropylphenyl)-6-methylp...Several nickel complexes [N,N]NiBr_2, in which [N,N] indicates bidentatenitrogen-containing ligands (1: [N,N]=N-(2,6-diisopropylphenyl)pyridine-2-carboxaldimine(C_(18)H_(22)N_2); 2: N-(2,6-diisopropylphenyl)-6-methylpyridine-2-carboxaldimine (C_(19)H_(24)N_2);3: N-(2,4,6-trimethylphenyl)pyridine-2-carboxaldimine(C_(15)H_(16)N_2); 4:N-(2,4,6-trimethylphenyl)-6-methylpyridine-2-carboxaldimine (C_(16)H_(18)-N_2) were synthesized.Some of the nickel complexes exhibit high activity for ethylene oligomerizatiori in the presence ofan organoaluminum activator. The main factor affecting the activity and the structure of oligomersis the steric effect of substituents on [N,N] ligands. Methylaluminoxane (MAO) -activated catalystsshowed higher activities and produced oligomers with higher molecular weight than Et_2AlCl-activatedones. The oligomerization in toluene rather than hexane results in much higher activity, and theoligomers produced in toluene have relatively high molecular weight. With activation of MAO orEt_2AlCl, the [N,N]NiBr_2 system tended to produce highly branched oligomers with low α-olefincontent, but the α-olefin content could be increased by changing the reaction conditions.展开更多
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.
基金Financial support was obtained from the State Key Laboratory of Petroleum Molecular&Process Engineering(24-ZC0607-0099)the Natural Science Foundation of China(21706177 and 22378293).
文摘A series of Ni/ZSM-5 containing a small amount of Ni was prepared by an ion exchanged method.The impact of the n(SiO_(2))/n(Al_(2)O_(3))ratio on the catalytic activity was studied using the samples 0.09Ni/ZSM-5(60)and 0.09Ni/ZSM-5(130).To determine the interaction between the Ni species and acid sites on the surface of the catalyst,the catalysts were characterized by N2 adsorption-desorption,X-ray diffraction(XRD),scanning electron microscopy(SEM),and UV-vis spectroscopy.The performance of the catalysts for the catalytic oligomerization of 1-hexene was investigated in detail.The nickel species were found to be uniformly distributed in all the catalysts.It was discovered that the oligomerization activity of the catalyst can be improved using Ni species;however,the contribution of Brønsted acids in oligomerization reactions is greater than that of Ni sites and Lewis acids.
基金Supported by National Natural Science Foundation of China,No.82104747 and No.82305133Basic and Applied Basic Research Foundation of Guangdong Province,China,No.2020A1515110947+1 种基金General Project of Shenzhen Science and Technology Innovation Commission,No.JCYJ20230807094659030,No.JCYJ20230807094805012,No.JCYJ20210324111602007,and No.JCYJ20220531091815034the Scientific Research Project of Guangdong Provincial Bureau of Traditional Chinese Medicine,No.20221349.
文摘BACKGROUND Gastric intestinal metaplasia(IM)is a precancerous lesion that is associated with an elevated risk of gastric carcinogenesis.Weiwei Decoction(WWD)is a promising traditional Chinese herbal formula widely employed in clinical for treating IM.Previous studies suggested the potential involvement of the olfactomedin 4(OLFM4)/nucleotide-binding oligomerization domain 1(NOD1)/caudal-type homeobox gene 2(CDX2)signaling pathway in IM regulation.AIM To verify the regulation of the OLFM4/NOD1/CDX2 pathway in IM,specifically investigating WWD’s effectiveness on IM through this pathway.METHODS Immunohistochemistry for OLFM4,NOD1,and CDX2 was conducted on tissue microarray.GES-1 cells treated with chenodeoxycholic acid were utilized as IM cell models.OLFM4 short hairpin RNA(shRNA),NOD1 shRNA,and OLFM4 pcDNA were transfected to clarify the pathway regulatory relationships.Protein interactions were validated by coimmunoprecipitation.To explore WWD’s pharmacological actions,IM rat models were induced using N-methyl-N’-nitro-N-nitrosoguanidine followed by WWD gavage.Gastric cells were treated with WWD-medicated serum.Cytokines and chemokines content were assessed by enzyme-linked immunosorbent assay and quantitative reverse transcription polymerase chain reaction.RESULTS The OLFM4/NOD1/CDX2 axis was a characteristic of IM.OLFM4 exhibited direct binding and subsequent downregulation of NOD1,thereby sustaining the activation of CDX2 and promoting the progression of IM.WWD improved gastric mucosal histological lesions while suppressing intestinal markers KLF transcription factor 4,villin 1,and MUCIN 2 expression in IM rats.Regarding pharmacological actions,WWD suppressed OLFM4 and restored NOD1 expression,consequently reducing CDX2 at the mRNA and protein levels in IM rats.Parallel regulatory mechanisms were observed at the protein level in IM cells treated with WWD-medicated serum.Furthermore,WWD-medicated serum treatment strengthened OLFM4 and NOD1 interaction.In case of antiinflammatory,WWD restrained interleukin(IL)-6,interferon-gamma,IL-17,macrophage chemoattractant protein-1,macrophage inflammatory protein 1 alpha content in IM rat serum.WWD-medicated serum inhibited tumor necrosis factor alpha,IL-6,IL-8 transcriptions in IM cells.CONCLUSION The OLFM4/NOD1/CDX2 pathway is involved in the regulation of IM.WWD exerts its therapeutic efficacy on IM through the pathway,additionally attenuating the inflammatory response.
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.
基金financial support from the National Key Technology R&D Program (2012BAE05B01) of China
文摘The objective of this study is to explore the optimum composition of Y and ZSM-5 zeolites to develop novel catalysts for obtaining lower gasoline olefins content and higher propylene yield. Five composite zeolite catalysts with varying Y zeolite/ZSM-5 zeolite ratios have been prepared in this work to investigate the synergy between the Y zeolite and ZSM-5 zeolite on the selectivity to protolytic cracking, β-scission, oligomerization, and hydrogen transfer reactions using a FCC naphtha feedstock at 480 ℃ in a confined fluidized bed reactor. Experimental results showed that the composite catalyst with a Y zeolite/ZSM-5 zeolite ratio of 1:4 had the highest protolytic cracking and β-scission ability, which was even higher than that of pure ZSM-5 catalyst. On the other hand, the catalyst with a Y zeolite/ZSM-5 zeolite ratio of 3:2 exhibited the strongest hydrogen transfer functionality while the pure Y zeolite based catalyst had the highest oligomerization ability. For all the catalysts tested, increasing conversion enhanced the selectivity to protolytic cracking and hydrogen transfer reactions but reduced the selectivity to β-scission reaction. However, no clear trend was identified for the selectivity to oligomerization when an increased conversion was experienced.
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.
文摘Olefin oligomerization reaction catalyzed by new catalyst systems(a Bronsted‐acidic ionic liquid as the main catalyst and tricaprylylmethylammonium chloride as the co‐catalyst)has been investigat‐ed.The synthesized Bronsted acidic ionic liquids were characterized by Fourier transform infrared spectroscopy(FT‐IR),ultraviolet‐visible spectroscopy(UV),^(1)H nuclear magnetic resonance(NMR),and^13 C NMR to analyze their structures and acidities.The influence of different ionic liquids,ionic liquid loading,different co‐catalysts,catalyst ratios(mole ratio of ionic liquid to co‐catalyst),reac‐tion time,pressure,temperature,solvent,source of reactants,and the recycling of catalyst systems was studied.Among the synthesized ionic liquids,1‐(4‐sulfonic acid)butyl‐3‐hexylimidazolium hydrogen sulfate([HIMBs]HSO4)exhibited the best catalytic activity under the tested reaction con‐ditions.The conversion of isobutene and selectivity of trimers were 83.21%and 35.80%,respec‐tively,at the optimum reaction conditions.Furthermore,the catalyst system can be easily separated and reused;a feasible reaction mechanism is proposed on the basis of the distribution of experi‐mental products.
基金the SINOPEC Corporation for the financial support
文摘1-Decene was oligomerized over the supported AlCl3/γ-Al2O3 catalyst in a fixed-bed reactor. The effects of temperature and LHSV on oligomerization of 1-decene were investigated and the synthetic PAO was characterized with GC technique. Furthermore, the life of immobilized catalyst was tested and the mechanism of catalyst deactivation was discussed. The results showed that with an increasing temperature, the PAO yield increased and the kinematic viscosity of oil decreased. The GC results indicated that the synthesized PAO was a mixture consisting of dimers, trimers, tetramers and pentamers. The results of chloride content measurements and BET tests showed that catalyst deactivation could be mainly attributed to the loss of active components.
基金National Natural Science Foundation of China （39925018, 90508002 , 30121001） Chinese Academy of Science （KSCX 1-R65 and RSCX2-H10）+2 种基金 National Basic Research Program of China （973 project, 2002CB713700） American Cancer Society （RPG-99-173-01） a Gcc Breast Cancer Research award and National Institutes of Health grants DK56292 and CA89019 to XY （a GCC Eminent Scholar） and NS36194 （JW）.
文摘During cell division, chromosome segregation is orchestrated by the interaction of spindle microtubules with the centromere. A dramatic remodeling of interpolar microtubules into an organized central spindle between the separating chromatids is required for the initiation and execution ofcytokinesis. Central spindle organization requires mitotic kinesins, the chromosomal passenger protein complex, and microtubule bundling protein PRC 1. PRC 1 is phosphorylated by Cdc2 at Thr470 and Thr481 during mitosis. However, the functional relevance of PRC 1 phosphorylation at Thr470 has remained elusive. Here we show that expression of the non-phosphorylatable mutant PRC 1T470A but not the phospho-mimicking mutant PRC 1^T470E causes aberrant organization of the central spindle. Immunoprecipitation experiment indicates that both PRC 1^T470A and PRC 1^T470E mutant proteins associate with wild-type PRC 1, suggesting that phosphorylation of Thr470 does not alter PRC 1 self-association. In addition, in vitro co-sedimentation experiment showed that PRC 1 binds to microtubule independent of the phosphorylation state of Thr470. Gel-filtration experiment suggested that phosphorylation of Thr470 promotes oligomerization of PRC 1. Given the fact that prevention of the Thr470 phosphorylation inhibits PRC 1 oligomerization in vitro and causes an aberrant organization of central spindle in vivo, we propose that this phosphorylation-dependent PRC 1 oligomerization ensures that central spindle assembly occurs at the appropriate time in the cell cycle.
文摘Nucleotide-binding oligomerization domain 1(NOD1) is an intracellular innate immune sensor for small molecules derived from bacterial cell components. NOD1 activation by its ligands leads to robust production of pro-inflammatory cytokines and chemokines by innate immune cells, thereby mediating mucosal host defense systems against microbes. Chronic gastric infection due to Helicobacter pylori(H. pylori) causes various upper gastrointestinal diseases, including atrophic gastritis, peptic ulcers, and gastric cancer. It is now generally accepted that detection of H. pylori by NOD1 expressed in gastric epithelial cells plays an indispensable role in mucosal host defense systems against this organism. Recent studies have revealed the molecular mechanism by which NOD1 activation caused by H. pylori infection is involved in the development of chronic gastritis and gastric cancer. In this review, we have discussed and summarized how sensing of H. pylori by NOD1 mediates the prevention of chronic gastritis and gastric cancer.
基金National Natural Science Foundation of China (No.30672285)Qingdao Municipal Science and Technology Commission,China (No.10-3-3-10-NSH)
文摘AIM: To investigate the expression of nucleotide oligomerization domain 2 (NOD2) in the immortalized human corneal epithelial cell line (THCE), and its role in the innate immune response triggered by inactive Aspergillus fumigatus (Af) conidia. METHODS: The normal THCE cells were investigated as controls. After incubation with inactive Af conidia for 0.5, 2, 4, 6, and 8 hours, THCE cells were harvested, mRNA expression of NOD2 and receptor interacting protein 2 (RIP2) was detected by RT-PCR. Intracellular proteins including NOD2, NF-kappa B and proinflammatory cytokines such as TNF-alpha, IL-8, IL-6 in the cell supernatant were analyzed by ELISA. RESULTS: Our data indicate that NOD2 expressed in the normal THCE cells. After triggered by the inactive Af conidia, the expression of NOD2, RIP2 mRNA and the secretion of NOD2, NF-kappa B, TNF-alpha, IL-8, IL-6 both increased in a time-depended manner, and reached the peak point at 4, 6, 6, 4, 6, 6, 4 hours, respectively. And after pretreated with NOD2 neutralizing antibody, the expression of RIP2, NF-kappa B, TNF-alpha, IL-8 both decreased dramatically at the peak point, while the secretion of IL-6 changed little. CONCLUSION: The results of this study suggest that NOD2 exists and expresses in the THCE cells, and contributes to the innate immune responses triggered by inactive Afconidia by induction of proinflammatory cytokines such as TNF-alpha and IL-8 through the NF-kappa B pathway.
基金financially supported by the National Natural Basic Research Program of China(No.2011CB606001)
文摘A series of nickel（II） α-diimine complexes with strong electron-withdrawing carboxyl groups, having reactive hydrogen atoms, were prepared and used as precatalysts for ethylene oligomerization and/or polymerization. The influence of metal halides and ligand structure on the catalytic activity and properties of products was investigated. The results showed that nickel bromide was much more active than nickel chloride, and the substituents at the ortho-position of aryl ring had large influence on the properties of products. Therefore, the products ranging from liquid oligomers to polymers could be readily obtained by the variation of the substituents on the ligands and reaction conditions.
文摘The chemoselectivities of PdCl2 and CuCl2-catalyzed oligomerization of 3, 3-dimethyl-butyne: 1, 3, 5-tri-tert-butylbenzene, 2, 2, 7, 7-tetramethyl-3, 6-dichloro-3, 5-octadiene and 2, 2, 7, 7- tetramethyl-3, 5-octadiyne were obtained, respectively, by regulating the polarity of the solvent.
文摘The structure of Ni active sites supported on amorphous silica-alumina supports with different contents of Al_(2)O_(3)loadings in relation to their activities in ethylene oligomerization were investigated.Two kinds of Ni sites were detected by in situ FTIR-CO and H_(2)-TPR experiments,that are Ni^(2+)cations as grafted on weak acidic silanols and Ni^(2+)cations at ion-exchange positions.The ethylene oligomerization activities of these Ni/ASA catalysts were found an ascending tendency as the Al_(2)O_(3)loading decreased,which could be attributed to the enriched concentration of Ni^(2+)species on acidic silanols with a weaker interaction with the amorphous silica-alumina support.These Ni^(2+)species were more easily to be evolved into Ni^(+)species,which has been identified to be the active sites of ethylene oligomerization.Thus,it seems reasonable to conclude that Ni^(2+)species grafted on acidic silanols were the precursors of active sites.
基金This work is supported by PetroChina Company Limited (No.030414-01)
文摘Novel Ni（II）-based acetyliminopyridine complexes 1b, 2b, 3b （1-3b）, which are synthesized from ligands 1a, 2a, 3a （1-3a） and [NiCl2（DME）], are suitable precursors for the catalysts that are necessary for ethylene oligomerization and polymerization reactions, activated by methylaluminoxane （MAO）. The MAO-treated 1-3b presents an active catalytic center, which may oligomerize and polymerize ethylene to produce linear α-olefins and polyethylene, respectively. The molecular weight distributions of oligomers that are obtained are in good agreement with the Schulz-Flory rules for oligomers〉C4. The activity of 3b-MAO complex is 6.3×10^7 g/（molNi.h） at 50 ℃. The activities and molecular weight distributions of oligomers show significant reliance on the structures of catalyst precursors.
文摘Ethylene oligomerization using ZSM-5 zeolite was investigated to study the role of Bronsted acid sites in the formation of higher hydrocarbons. The oligomerization of olefins, dependent on the acidity of ZSM-5 zeolite, is an important step in the conversion of natural gas to liquid fuels. The framework Si/Al ratio reflects the number of potential acid sites and the acid strength of the ZSM-5 catalyst. ZSM-5 with the mole ratio SiO2/Al2O3 equal to 30 was dealuminated for different periods of time according to the acidic ion-exchange method to produce ZSM-5 with various Si/Al ratios. The FT-IR analysis revealed that the integrated framework aluminum band, non-framework aluminum band, and silanol groups areas of the ZSM-5 zeolites decreased after being dealuminated. The performance of the dealuminated zeolite was tested for ethylene oligomerization. The results demonstrated that the dealumination of ZSM-5 led to higher ethylene conversion, but the gasoline selectivity was reduced compared to the performance of a ZSM-5 zeolite. The characterization results revealed the amount of aluminum in the zeolitic framework, the crystallinity of the ZSM-5 zeolite, and the Si/Al ratio affected the formation of Bronsted acid sites. The number of the Bronsted acid sites on the catalyst active sites is important in the olefin conversion to liquid hydrocarbons.
基金This work was subsidized by Special Funds for Major State Basic Research Projects of China(No.G1999064801).
文摘Several nickel complexes [N,N]NiBr_2, in which [N,N] indicates bidentatenitrogen-containing ligands (1: [N,N]=N-(2,6-diisopropylphenyl)pyridine-2-carboxaldimine(C_(18)H_(22)N_2); 2: N-(2,6-diisopropylphenyl)-6-methylpyridine-2-carboxaldimine (C_(19)H_(24)N_2);3: N-(2,4,6-trimethylphenyl)pyridine-2-carboxaldimine(C_(15)H_(16)N_2); 4:N-(2,4,6-trimethylphenyl)-6-methylpyridine-2-carboxaldimine (C_(16)H_(18)-N_2) were synthesized.Some of the nickel complexes exhibit high activity for ethylene oligomerizatiori in the presence ofan organoaluminum activator. The main factor affecting the activity and the structure of oligomersis the steric effect of substituents on [N,N] ligands. Methylaluminoxane (MAO) -activated catalystsshowed higher activities and produced oligomers with higher molecular weight than Et_2AlCl-activatedones. The oligomerization in toluene rather than hexane results in much higher activity, and theoligomers produced in toluene have relatively high molecular weight. With activation of MAO orEt_2AlCl, the [N,N]NiBr_2 system tended to produce highly branched oligomers with low α-olefincontent, but the α-olefin content could be increased by changing the reaction conditions.
