氨水重碳化过程的直线操作法

该文介绍了一种控制氨水重碳化过程生产碳酸氢铵的新操作方法。它以控制碳酸氢铵结晶过程为中山，对碳化系统提出了一系列改革，对提高碳铵产量、质量、搞好氨平衡，减少事故，稳定生产带来很大好处，可大幅度提高工厂生产效益。

电溶WC的重碳化处理工艺研究

通过对电溶WC粉重碳化前后粉末化学成分的变化及其制取的WC-8%Co合金物理机械性能及金相组织结构的对比研究,证示重碳化后电溶WC粉中的杂质含量大为降低,氧含量由0.21%下降至0.074%,Mg、Cd、Ca、Na等均呈数量级的下降。WC颗粒比碳化之前要明显地长粗,生产的合金的密度比普通电溶WC制取的合金要高,孔隙度明显降低,宏观孔洞消除,抗弯强度提高达14%。

炭化重竹琴马试用于402扬琴的声学分析研究

本文对以优选炭化重竹制成的扬琴琴马用于扬琴演奏中的声学效应进行分析、研究,旨在寻求更佳的材料,以实现扬琴声音品质的提升。"碳化重竹"是目前在民用建筑领域(仿古家具、仿红木地板)广泛用于替代珍稀木材的主要材料之一。将其作为实验材料,主要考虑到:1.其材料本身就是为替代红木而研发的,将其运用于扬琴琴马制作对扬琴声音的品质具有可控性;2.其主要成分为竹材,有相当的生态意义;3.目前此材料技术比较成熟,但并未受到乐器制造业的关注。因此,可以作为"以竹代木"用于扬琴制作的一个新的尝试。文章主要是运用比较分析的方法,进行实验设计与分析,其主要内容包括:一、碳化重竹材料的来源及介绍;二、实验设计;三、实验过程;四、实验分析及结论。

Insight into MgO promoter with low concentration for the carbon-deposition resistance of Ni-based catalysts in the CO_2 reforming of CH_4

The CO2reforming of CH4is studied over MgO‐promoted Ni catalysts,which were supported on alumina prepared from hydrotalcite.This presents an improved stability compared with non‐promoted catalysts.The introduction of the MgO promoter was achieved through the‘‘memory effect’’of the Ni‐Al hydrotalcite structure,and ICP‐MS confirmed that only0.42wt.%of Mg2+ions were added into the Ni‐Mg/Al catalyst.Although no differences in the Ni particle size and basicity strength were observed,the Ni‐Mg/Al catalyst showed a higher catalytic stability than the Ni/Al catalyst.A series of surface reaction experiments were used and showed that the addition of a MgO promoter with low concentration can promote CO2dissociation to form active surface oxygen arising from the formation of the Ni‐MgO interface sites.Therefore,the carbon‐resistance promotion by nature was suggested to contribute to an oxidative environment around Ni particles,which would increase the conversion of carbon residues from CH4cracking to yield CO on the Ni metal surface.?2018,Dalian Institute of Chemical Physics,Chinese Academy of Sciences.Published by Elsevier B.V.All rights reserved.

Kinetic Study on CO_2 Reforming of Methane

The kinetics of CO2 reforming of methane has been studied at 976－1033K on a commercial NiO/CaO/Al2O3 catalyst in a packed-bed continuous reactor. The reaction was carried out at atmospheric pressure and CO2/CH4 ratio ＞ 2. The Hougen-Watson rate models were fitted to experimental data assuming the disso ciative adsorption of methane as the rate-determining step. The reaction rate showed an effective reaction order of about unity for CH4. The apparent activity energy was found to be 104 kJ·mol-1. Therefore the kinetic reaction parameters were determined and a possible reaction mechanism was proposed.

Reactivities of Shenfu Chars Toward Gasification with Carbon Dioxide

Five Shenfu char samples were prepared from Shenfu raw coal at different temperatures （950, 1100, 1200, 1300 and 1400℃） using a muffle furnace. Demineralization of the char samples was performed by treating them with 10% nitric acid for 10 min in a CEM Discover microwave reactor. The gasification of the chars, and corresponding demineralized chars, in a carbon dioxide （CO2） atmosphere was conducted in a Netzsch STA 409Cl31F tempera- ture-programmed thermogravimetry apparatus. The effects of charring temperature and demineralization on the gasification reactivity of chars were systematically investigated. The results show that a char formed at a lower temperature is more reactive except for demineralized char formed at 1100℃, which is less reactive than char formed at 1200℃. Demineralization decreases the char reactivities toward gasification with CO2 to a small extent.

Carbon dioxide reforming of methane over bimetallic catalysts of Pt-Ru/γ-Al_2O_3 for thermochemical energy storage

The reaction of CO2 reforming of CH4 has been investigated with y-A1203-supported platinum and ruthenium bimetallic catalysts, with the specific purpose of thermochemical energy storage. The catalysts were prepared by using the wetness impregnation method. The prepared catalysts were characterized by a series of physico-chemical characterization techniques such as BET surface area, thermo-gravimetric （TG）, transmission electron microscope （TEM） and X-ray photoelectron spectroscopy （XPS）. In addition, the amount of carbon deposits on the surface of the catalysts and the type of the carbonaceous species were discussed by TG. It was found that the bimetallic Pt-Ru/7-A1203 catalysts exhibit both superior catalytic activity and remarkable stability by comparison of monometallic catalysts. During the 500 h stability test, the bimetallic catalyst showed a good performance at 800 ~C in CO2 reforming of CH4, exhibiting an excellent anti-carbon performance with the mass loss of less than 8.5%. The results also indicate that CO2 and CH4 have quite stable conversions of 96.0 % and 94.0 %, respectively. Also, the selectivity of the catalysts is excellent with the products ratio of CO/H2 maintaining at 1.02. Furthermore, it was found in TEM images that the active carbonaceous species were formed during the catalytic reaction, and well-distributed dot-shaped metallic particles with a relatively uniform size of about 3 nm as well as amorphous carbon structures were observed. Combined with BET, TG, TEM tests, it is concluded that the selected bimetallic catalysts can work continuously in a stable state at the high temperature, which has a potential to be utilized for the closed-loop cycle of the solar thermochemical energy storage in future industry applications.

Effects of salinity and body mass on oxygen consumption and ammonia excretion of mudskipper Boleophthalmus pectinirostris

We evaluated the effects of salinity and body mass on the oxygen consumption rate and ammonia excretion rate of mudskipper Boleophthalmus pectinirostris under laboratory conditions. Salinity and body mass had highly significant effects on the oxygen consumption rate （Ro） and ammonia excretion rate （RN） （P〈0.01）. The interactive effects between salinity and body mass on Ro and RN were insignificant （P〉0.05） and highly significant （P〈0.01）, respectively. Ro and RN of B. pectinirostris decreased significantly as the individual body mass increased. The relationship between Ro and body mass was represented by Ro=aWb （R^2=0.956, P〈0.01）. The relationship between RN and the body mass ofB. pectinirostris was represented by RN-cW^at （R^2=0.966, P〈0.01）. The Ro/RN （O：N） ratios increased significantly as the salinity increased from 12 to 27, but decreased as salinity increased from 27 to 32. The atomic O：N ratios were significantly higher at 27 than at other salinity levels. The average O：N ratio was 25.25. Lipid and carbohydrate were the primary energy sources and protein was the secondary energy significantly higher at 27 than at other salinity levels B, pectinirostris is 27. source within the salinity range 12 32. Ro andRN were Our results suggest that the optimum salinity level for B. pectinirostris is 27.

Non-alcoholic fatty liver disease and the metabolic syndrome:Effects of weight loss and a review of popular diets,Are low carbohydrate diets the answer?

Non-alcoholic fatty liver disease （NAFLD） encompasses a wide spectrum of fat-induced liver injury, ranging from relatively benign steatosis to cirrhosis and liver failure. The presence of obesity and insulin resistance is strongly associated with non-alcoholic fatty liver and confers on it a greater risk of histologically advanced disease. There is a growing concern in the medical profession as the prevalence of this disease continues to rise in parallel with the rise in obesity and the metabolic syndrome. Treatment options are limited and dietary weight loss is often advised. Low fat diets are difficult to adhere to and recent studies have shown the potential of low carbohydrate diets for weight loss and improving insulin resistance. Thus far, no study has evaluated the effect of low carbohydrate diets on NAFLD. Future studies will be required to address this question and others with regards to the nutritional adequacy and long-term side effects of these diets.

Reforming of Methane by CO2 over Bimetallic Ni-Mn/γ-Al2O3 Catalyst

γ-Al2O3 supported Ni-Mn bimetallic catalysts for CO2 reforming of methane were prepared by impregnation method. The reforming reactions were conducted at 500-700℃ and atmospheric pressure using CO2/CH4/N2 with feed ratio of 17/17/2, at total flow rate of 36 mL/min. The catalytic performance was assessed through CH4 and CO2 conversions, synthesis gas ratio （H2/CO） and long term stability. Catalytic activity and stability tests revealed that addition of Mn improved catalytic performance and led to higher stability of bimetallic catalysts which presented better coke suppression than monometallic catalyst. In this work, the optimum loading of Mn which exhibited the most stable performance and least coke deposition was 0.5wt%. The fresh and spent catalysts were characterized by various techniques such as Brunauer-Emmett-Teller, the temperature programmed desorption CO2- TPD, thermogravimetric analysis, X-ray diffraction, scanning electron microscope, EDX, and infrared spectroscopy.

VDC调节阀的检修技巧

通过对重碱碳化塔冷却系统十台气动调节阀外泄的检修实践 ,提出根据调节阀的实际故障状况制定适合本企业低成本高质量的检修方案 ,文章介绍了经实践检验这个检修技巧。

Novel synthesis of nickel oxide microsphere with high surface area and its catalytic application for carbon dioxide reforming of methane

Nickel oxide(NiO)microsphere with a large surface area was novelly synthesized through nickel bicarbonate(Ni(HCO3)2)precursor.The obtained nickel oxide(NiO)microsphere was characterized by X-ray pattern diffraction,scanning electron microscopy,CO2 temperature-programmed desorption,H2 temperature-programmed reduction,N2 adsorption/desorption and laser scattering particle size distribution analyzer.It was found that nickel oxide(NiO)synthesized by the thermal decomposition of Ni(HCO3)2through area hydrolysis,presented very nice microsphere with high surface area.The catalytic properties of obtained nickel oxide(NiO)microsphere were studied in the reaction of carbon dioxide reforming of methane where 91.3% conversion of CH4 with 93% conversion of CO2 was observed.Besides,the catalyst maintained high stability over 200 h on the stream.

Probing the catalytic behavior of ZnO nanowire supported Pd_1 single-atom catalyst for selected reactions

We have dispersed individual Pd atoms onto ZnO nanowires(NWs)as single‐atom catalysts(SACs)and evaluated their catalytic performance for several selected catalytic reactions.The Pd1/ZnO SAC is highly active,stable,and selective towards CO2for steam reforming of methanol to produce hydrogen.This catalyst system is active for oxidation of CO and H2but performs poorly for preferential oxidation of CO in hydrogen‐rich stream primarily due to the strong competitive oxidation of H2on ZnO supported Pd1atoms.At ambient pressure,reverse water‐gas‐shift reaction occurs on the Pd1/ZnO SAC.This series of tests of catalytic reactions clearly demonstrate the importance of selecting the appropriate metal and support to develop SACs for catalytic transformation of molecules.

New Catalytic Proportions for Syntheses of SWNT Bundles (Ropes) and Its Characterization

The single-walled carbon nanotube（SWNT） bundles and ropes have been prepared by using the anode are discharge plasma to evaporate the graphite rods which contain Fe, Co and Ni powders as catalyst in He atmosphere. Many purifying methods are used for the products. It indicates that the synthesis of SWNTs has been greatly affected by the preparation parameters of catalyzer, the buffer gas and its pressure, the arc current intensity, etc. The optimal condition for preparing SWNTs in our case has been proposed. The forming mechanism of the SWNTs bundles and ropes is also studied qualitatively. The evaporated single graphite sheet tends to reduce its active energy.

Hydrochemical characteristics of aquifers in Northern Gezira State,Central Sudan

This paper presents an assessment of the hydrochemical characteristics of groundwater in Northern Gezira State, Central Sudan. The approaches followed here include the chemical analyses for major ions chemistry and construction of hydrochemical maps of total dissolved solids (TDS), sodium (Na +), bicarbonate (HCO 3 -), and chloride (Cl -) ions. The hydrochemical characteristics of the groundwater in each aquifer and management consideration are discussed. Sources of major ions in groundwater are analyzed. The hydrochemical maps of important species are constructed. The relationship of groundwater to use is elaborated. High concentrations of the chemical and hydrochemical constituents and the occurrence of calcretes (CaCO 3) in upper zones suggest a long history of evaporation and increasing leachates.

AMPK Subunit Expression Regulates Intramuscular Fat Content and Muscle Fiber Type in Chickens

The objective of this study was to assess the role of AMPK in intramuscular fat(IMF) and fiber type in chicken muscle. The chickens were slaughtered and their muscles were collected at the ages of 4, 8, and 16 weeks so as to determine the IMF contents, as well as the expression levels of AMPK subunits, regulators of adipogenesis. In addition, the myosin heavy chains(My HCs) in thigh muscle tissues were also measured. The results showed that the IMF contents in 16-week old chickens were higher than those in 4 and 8-week-old chickens(P<0.05).The expression levels of fatty acid synthase(FAS) and fatty aicd translocase CD36(FAT/CD36) m RNA were increased significantly in samples collected at the ages of4 and 16 weeks(P<0.05). The expression levels of My HC IIa and IIb differed significantly among all the developmental stages(P <0.05). The AMPKα2, AMPKγ1,and AMPKγ3 m RNA levels were dramatically decreased with the increase of age(P <0.05). To examine the role of AMPK in adipogenesis regulation, the SV cells were cultured in an adipogenesis medium and treated with AICAR and Compound C respectively, the specific activator and inhibit of AMPK. The Compound C induced dramatically a greater expression of C/EBPβ, SREBP1 and PPARγ(P <0.05). In conclusion, the expression of AMPKα2, AMPKγ1, and AMPKγ3 m RNA is significantly correlated with the adipogenesis in skeletal muscle of chickens.

Stereoselective synthesis of 2-deoxy-pyranosides via the Lewis acid-promoted rearrangement of 2,3-anhydrothiosugars

An efficient method for the preparation of 2-deoxy-glycopyranosides was developed by using 2,3-anhydrothioglycosides as the glycosylating agents.The reaction proceeded by the Cu(OTf)_2-mediated rearrangement of 2,3-anhydrothiosugars.And high anomeric stereoselectivity was achieved.The disclosed methodology may find applications in the preparation of many biologically important 2-deoxy-glycosides.

Hydrogen production through CO_2 sorption-enhanced methane steam reforming:Comparison between different adsorbents

A two-dimensional transient model has been developed to describe the catalytic methane reforming （MSR） coupled with simultaneous CO2 removal by different absorbents under non-isothermal, non-isobaric and non-adiabatic operating conditions. The influences of temperature, pressure and steam/carbon （S/C） on enhancement were taken into account. The results showed that the hydrogen mole fraction （dry basis） higher than 94% could be achieved using Li4SiO4, CaO, and HTC as CO2 acceptors at the operating conditions of 550~C and 0.1 MPa. When the reaction temperature varied from 500℃ to 600℃, the initial CO2 capture rates were HTC〉CaO〉Li4SiO4〉LizZrO3, and the saturation rates HTC〉CaO〉Li4SiOg〉Li2ZrO3. Increasing the reaction temperature would improve the CO2 capture rate and available CO2 capacity. For Li4SiO4, although the adsorbing rate increased as the operating temperature increased, the capacity almost did not change. At 550℃, increasing the working pressure could promote the enhancing factors of Li4SiO4,Li2ZrO3 and HTC. There was an optimal steam/carbon ratio between 2-4.5 such that all CaO, Li4SiO4, HTC and Li2ZrO3 would obtain the biggest enhancement for H2 production at the pre-breakthrough stage.

Promotional effect of cerium on nickel-containing mesoporous silica for carbon dioxide reforming of methane

A series of Ce-promoted 6.7%Ni-containing mesoporous silica(Ce-Ni-Si O2)with varying Ce content(0.5%–4.8%)was prepared using the evaporation-induced self-assembly method.The characterization results showed that Ce and Ni species were homogeneously incorporated into the mesoporous silica matrix.The catalytic properties of these samples in the dry reforming of methane reaction revealed that the catalysts(e.g.,1.2%Ce-Ni-Si O2)containing highly dispersed small Ni particles exhibited excellent catalytic activity and long-term stability,which is attributed to the anchoring effect of the Ce and its ability to increase surface oxygen species concentration.

Characteristics of carbonate cementation in clastic rocks from the Chang 6 sandbody of Yanchang Formation, southern Ordos Basin

Densification of reservoir is an important factor that restricts oil and gas exploration from low porosity and extra-low permeability reservoirs. Carbonate cementation was heavily developed in Chang 6 sandbody, a facies of underwater distributary channel in delta front, of Upper Triassic Yanchang Formation in Fuxian area, southern Ordos Basin, and the cementation is one of the major factors that affect quality of reservoir. Based on the macro-microcosmic petrology and geochemistry features, the genesis of densification of carbonate-cemented reservoir was systematically discussed. The carbonate cementation can be classified into endogenous and exogenous, and the essential differences between them are that they were formed in different fluids and in different diagenesis periods. With the aid of identification of thin sections, analyses on electron probe, trace and rare-earth elements, carbon and oxygen isotope, we propose that the endogenous fluid for cementation came from the rock itself during early diagenetic stage. The minerals related to endogenous fluid had good shapes. The reservoir property was enhanced with porosity increasing by 3%-8% because of later dissolution by endogenous fluid. The exogenous fluid might be water combining with CO 2 , likely released from organic matter-rich mudstone. Calcite cement, in form of substrate cementation, was precipitated from the fluid and filled in the remaining pores of sandstones in late diagenetic stage as variations of physical and chemical conditions. The exogenous cement reduced rock porosity, damaged reservoir property, affected some oil enrichment, and seriously caused Chang 6 reservoir densification. Some of the dense layers that formed on top of sandbody could have served as diagenetic traps, and thus the exogenous cementation area could be favorable for oil exploration.