Modifying the acidity of H-MOR and its catalytic carbonylation of dimethyl ether

Among the reactions catalyzed by zeolites there are some that exhibit high selectivity due to the spatial confinement effect of the zeolite framework.Tailoring the acidity,particularly the distribution and location of the Bronsted acid sites in the zeolite is effective for making it a better catalyst for these reactions.We prepared a series of H-mordenite（H-MOR） samples by varying the composition of the sol-gel,using different structure directing agents and post-treatment.NH3-TPD and IR characterization of adsorbed pyridine were employed to determine the amount of Bronsted acid sites in the 8-membered ring and 12-membered ring channels.It was shown that controlled synthesis was a promising approach to improve the concentration of Bronsted acid sites in MOR,even with a low Al content.Using an appropriate composition of Si and Al in the sol-gel favored a higher proportion of Bronsted acid sites in the 8-membered ring channels.HMI as a structure-direct agent gave an obvious enrichment of Bronsted acid sites in the 8-membered ring.Carbonylation of dimethyl ether was used as a probe reaction to examine the modification of the acid properties,especially the Bronsted acid sites in the 8-membered ring channels.There was a linear relationship between methyl acetate formation and the number of Bronsted acid sites in the 8-membered ring channels,demonstrating the successful modification of acid properties.Our results provide information for the rational design and modification of zeolites with spatial constraints.

A zirconium modified Co/SiO_2 Fischer-Tropsch catalyst prepared by dielectric-barrier discharge plasma

Co/SiO2 and zirconium promoted Co/Zr/SiO2 catalysts were prepared using dielectric-barrier discharge （DBD） plasma instead of the conventional thermal calcination method. Fischer-Tropseh Synthesis （FTS） performances of the catalyst were evaluated in a fixed bed reactor. The results indicated that the catalyst treated by DBD plasma shows the higher FTS activity and yield of heavy hydrocarbons as compared with that treated by the conventional thermal calcination method. Increase in CO conversion was unnoticeable on the Co/SiO2 catalyst, but significant on the Co/Zr/SiO2 catalyst, both prepared by DBD plasma. On the other hand, heavy hydrocarbon selectivity and chain growth probability （a value） were enhanced on all the catalysts prepared by the DBD plasma. In order to study the effect of the DBD plasma treatment on the FTS performance, the catalysts were characterized by N2-physisorption, H2-temperature programed reduction （H2-TPR）, H2-temperature- programmed desorption （H2-TPD） and oxygen titration, transmission electron microscope （TEM） and X-ray diffraction （XRD）. It was proved that, compared with the traditional calcination method, DBD plasma not only could shorten the precursor decomposition time, but also could achieve better cobalt dispersion, smaller Co304 cluster size and more uniform cobalt distribution. However, cobalt reducibility was hindered to some extent in the Co/SiO2 catalyst prepared by DBD plasma, while the zirconium additive prevented significantly the decrease in cobalt reducibility and increased cobalt dispersion as well as the FTS performance.

Coupling dynamic analysis of a liquid-filled spherical container subject to arbitrary excitation

Using spherical coordinates, the coupling nonlinear dynamic system of a liquid-filled spherical tank, which can be excited discretionarily, is deduced by the H-O varia- tional principle, and the viscous damping is introduced via the liquid dissipation function. The kinetic equations of the coupling system are deduced by the relationship between the velocity of liquid particles and the disturbed liquid surface equation. Normal differential equations are obtained through the Galerkin method. An equivalent mechanical model is developed for liquid sloshing in a spherical tank subject to arbitrary excitation. The fixed and slosh masses, as well as the spring and damping constants, are determined in such a way as to satisfy the principle of equivalence. Numerical simulations illustrate the theoretical results in this paper as well.

Cobalt catalysts for Fischer–Tropsch synthesis： The effect of support,precipitant and pH value

In this report,Co-based catalysts supported on ZnO,Al_2O_3 and ZrO_2 as well as the ZrO_2 derived from different precipitants and different pH values were prepared by co-precipitation method.Their catalytic Fischer–Tropsch synthesis(FTS)performance was investigated in a fixed-bed reactor.The results revealed that Co catalyst supported on ZrO_2 exhibited better FTS catalytic performance than that supported on ZnO or Al_2O_3.For the Co/ZrO_2catalyst,different precipitants showed the following an activity order of NaOH>Na_2CO_3>NH_4OH,and the best pH value is 13.The catalysts were characterized by N_2adsorption–desorption,XRF,XRD,H_2-TPR,H_2-TPD and TEM.It was found that the main factor affecting the CO conversion of the catalyst was the amounts of low-temperature active adsorption sites.Moreover,the selectivity of C_5^+hydrocarbons had a positive relationship with the peak temperature of the weak hydrogen adsorption sites.The higher the peak temperature,the higher the C_5^+selectivity is.

Transcriptome Analysis of Female and Male Henosepilachna vigintioctopunctata(Coleoptera:Coccinellidae)Identifies Sex-related Genes

Henosepilachna vigintioctopunctata is an emerging horticultural pest of Solanaceae plants in Asia.Here,we employed transcriptome sequencing of three female and three male H.vigintioctopunctata libraries to identify sex-related genes.We recorded 281599294 bp of clean reads,and de novo assembly generated 85206 unigenes,with N_(50) of 1311 bp and average length of 763 bp.We found 5002 genes highly expressed in males and 2179 genes highly expressed in females.Expression profiles of six unigenes specific to females,six unigenes specific to males,and ten unigenes common to both sexes were verified using semi-quantitive RT-PCR;results showed expression levels of these 22 unigenes were relatively consistent with the transcriptome analysis.Using all unigenes as references,we identified 6657 putative simple sequence repeats.The transcriptome sequences and gene expression profiles of female and male H.vigintioctopunctata help explore genetic mechanisms of sexual dimorphism.

The intra-day optical monitoring of BL Lacerate object 1ES 1218+304 at its highest X-ray flux level

We here report a monitor of the BL Lac object 1 ES 1218+304 in both B-and R-bands by the GWAC-F60 A telescope in eight nights,when it was triggered to be at its highest X-ray flux in history by the VERITAS Observatory and Swift follow-ups.Both ANOVA and χ^(2)-test enable us to clearly reveal an intraday variability in optical wavelengths in seven out of the eight nights.A bluer-when-brighter chromatic relationship has been clearly identified in five out of the eight nights,which can be well explained by the shock-in-jet model.In addition,a quasi-periodic oscillation phenomenon in both bands could be tentatively identified in the first night.A positive delay between the two bands has been revealed in three out of the eight nights,and a negative one in the other nights.The identified minimum time delay enables us to estimate the MBH=2.8 × 10^(7) M_(⊙) that is invalid.

Thermal decomposition and cobalt species transformation of carbon nanotubes supported cobalt catalyst for Fischer-Tropsch synthesis

The effect of calcination condition on the cobalt species and Fischer-Tropsch synthesis （FTS） was studied. It was found that higher calcination temperature resulted in decreased FTS activities because CNTs were consumed by oxidation in air at temperature higher than 230 ℃. Cobalt species went through transformation from Co304 to metallic Co in Ar by autoreduction at temperature over 500℃. The autoreduction route might be Co3O4→CoO→C0 or Co3O4→Co2C→Co. Reduction at temperature higher than 500 ℃ also resulted in decreased FTS activities due to the methanation of CNTs in hydrogen.

Transfer Trajectory Design for Mars Exploration

With regard to the human exploration of Mars, low energy transfer trajectory is designed for Mars exploration based on the combination of invariant manifolds, differential correction and aerobraking methods. The whole transfer trajectory is composed of four stages: 1) from the Earth parking orbit to the Lyapunov orbit around Lagrange point L2 in the Sun-Earth system;2) from the Lyapunov orbit around L2 to the Lyapunov orbit around L1 in the Sun-Mars system;3) from the Lyapunov orbit around L1 in the Sun-Mars system to the large elliptical orbit around Mars;and 4) from the large elliptical orbit around Mars to the near-Mars parking orbit. In the first three stages, the circular restricted three-body problem is considered, and the trajectory is designed by using invariant manifolds and the differential correction method. The simulation results show that the transfer trajectory designed by means of the invariant manifolds of the Lyapunov orbit costs lower energy and shorter time of flight than that designed by means of the invariant manifold of the Halo orbit. In the fourth stage, the two-body problem is considered, and the aerobraking method is applied. A comparative performance analysis of static and rotating atmospheric models is carried out by using the details of duration, aerodynamic loading of the Mars vehicle, and other orbital parameters. It is shown that, on the low periareon where the influence of the atmospheric density increases, the changes of orbit parameters between rotating and static atmospheric environments are in large difference, such as orbital semimajor axis, orbital eccentricity, and so on. The influence of Martian rotating atmospheric environment should be considered.

婴幼儿腹腔镜手术中二氧化碳气腹对米库氯铵作用时间的影响

目的探讨小儿腹腔镜手术二氧化碳CO_2气腹对米库氯铵作用时间的影响。方法选取全身麻醉气管插管下行择期腹股沟疝修补术的61例患儿,随机分为腹腔镜组(31例)和开腹组(30例)。静脉给予丙泊酚2.5 mg/kg、芬太尼2μg/kg及米库氯铵0.2 mg/kg进行麻醉诱导,术中吸入50%一氧化二氮N2O+50%氧气O_2+七氟醚维持麻醉,麻醉深度维持在1.2～1.4 MAC。使用肌松监测仪记录4个成串刺激(TOF);分别记录T_1完全消失时间(Ta)(即肌松药完全起效时间);T_1消失至T_1恢复到对照值25%的时间(Tb)(即肌松药有效作用时间)。检测手术前后24 h血浆胆碱酯酶(CHE)、谷丙转氨酶(ALT)、谷草转氨酶(AST)及总胆红素(TBIL)浓度。结果两组米库氯铵Ta、Tb比较,差异无统计学意义(P>0.05);两组术前、术后24 h的CHE、ALT、AST及TBIL浓度比较,差异无统计学意义(P>0.05)。结论婴幼儿CO_2气腹米库氯铵的完全起效时间和有效作用时间无影响。