Terminal Products Research Articles

Stress analysis of the subsea dynamic riser baseprocess piping

Thesubsea dynamic riser base (SDRB) is an important piece of equipment for the floating production platform mooring system. One end is connected to the rigid pipeline, carrying a rigid pipeline thermal expansion load and the other end is connected to a flexible riser, carrying the dynamic load of the flexible riser, so its function is a transition connection between the flexible riser and the rigid pipeline which fixes the flexible riser on the seabed. On the other hand, as a typical subsea product, the design will satisfy the requirements of the standards for subsea products. By studying the stress analysisphilosophy of the topside piping and subsea pipeline, a physical model and procedure for piping stress analysis of the SDRB have been established. The conditions of the adverse design load have been considered, and a combination of the static load from the rigid pipeline and the dynamic load flexibility has also been optimized. And a comparative analysis between the AMSE, DNV and API standards for piping stress with the checking rules has been done. Because the SDRB belongs to the subsea pipeline terminal product, the use of DNV standards to check its process piping stress is recommended. Finally, the process piping stress of the SDRB has been calculated, and the results show that the jacket pipe and the carrier pipe stress of the SDRB process piping satisfy the DNV standards as a whole.The bulkhead cannot be accurately simulated by the AutoPIPE software which uses the FEA software ANSYS in the detailed analysis, but the checking results will still meet the requirements of the DNV standards.

15-Deoxy-Δ12,14-prostaglandin J2 induces expression of 15-hydroxyprostaglandin dehydrogenase through Elk-1 activation in human breast cancer MDA-MB-231 cells

Overproduction of prostaglandin E2 (PGE2) has been reported to be implicated in carcinogenesis. The intracellular level of PGE2 is maintained not only by its biosynthesis, but also by inactivation/degradation. 15-Hydroxyprostaglandin dehydrogenase (15-PGDH) is the key enzyme that catalyzes the conversion of oncogenic PGE2 to a biologically inactive keto metabolite. In the present study, we demonstrate that 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2), one of the terminal products of cyclooxygenase-2, updregulates the expression and the activity of 15-PGDH in human breast cancer MDA-MB-231 cells. By using deletion constructs of the 15-PGDH promoter, we have found that E-twenty six (Ets) is the most essential determinant for 15-PGDH induction. 15d-PGJ2 induced phosphorylation of Elk-1, one of Ets transcription factor family members, in the nucleus. Knockdown of Elk-1 abolished the ability of 15d-PGJ2 to upregulate 15-PGDH expression. Furthermore, 15d-PGJ2-mediated activation of Elk-1 was found to be dependent on activation of extracellular-signal related kinase (ERK) 1/2. Treatment of U0126, a pharmacological inhibitor of MEK1/2-ERK, abolished phosphorylation and DNA binding of Elk-1 as well as 15-PGDH induction in 15d-PGJ2-treated MDA-MB-231 cells. Moreover, 15d-PGJ2 generated reactive oxygen species (ROS), which contribute to the expression of 15-PGDH as well as phosphorylation of ERK1/2 and Elk-1. 15d-PGJ2 inhibited the migration of MDA-MB-231 cells, which was attenuated by transient transfection with 15-PGDH siRNA. Taken together, these findings suggest that 15d-PGJ2 induces the expression of 15-PGDH through ROS-mediated activation of ERK1/2 and subsequently Elk-1 in the MDA-MB-231 cells, which may contribute to tumor suppressive activity of this cyclopentenone prostaglandin.

Redox conditions and trace metal cycling in coastal sediments from the maritime Antarctic

Redox-sensitive trace metals (Mn, Fe, U, Mo, Re), nutrients and terminal metabolic products (NO3-, NH4+, PO43-, total alkalinity) were investigated for the first time in pore waters of Antarctic coastal sediments. The results of this study reveal a high spatial variability in redox conditions in surface sediments from Potter Cove, King George Island, western Antarctic Peninsula. Particularly in the shallower areas of the bay the significant correlation between sulphate depletion and total alkalinity, the inorganic product of terminal metabolism, indicates sulphate reduction to be the major pathway of organic matter mineralisation. In contrast, dissimilatory metal oxide reduction seems to be prevailing in the newly ice-free areas and the deeper troughs, where concentrations of dissolved iron of up to 700μM were found. We suggest a combination of several factors to be responsible for the domination of metal oxide reduction over sulphate reduction in these areas. These include the increased accumulation of fine-grained material with high amounts of reducible metal oxides, a reduced availability of metabolisable organic matter and an enhanced physical and biological disturbance by bottom water currents, ice scouring and burrowing organisms. Based on modelled iron fluxes we calculate the contribution of the Antarctic shelf to the pool of potentially bioavailable iron (Feb) to be 6.9×103 to 790×103tyr−1. Consequently, these shelf sediments would provide an Feb flux of 0.35–39.5mgm−2yr−1 (median: 3.8mgm−2yr−1) to the Southern Ocean. This contribution is in the same order of magnitude as the flux provided by icebergs and significantly higher than the input by aeolian dust. For this reason suboxic shelf sediments form a key source of iron for the high nutrient-low chlorophyll (HNLC) areas of the Southern Ocean. This source may become even more important in the future due to rising temperatures at the WAP accompanied by enhanced glacier retreat and the accumulation of melt water derived iron-rich material on the shelf.

Helsingør Statement on poly- and perfluorinated alkyl substances (PFASs)

In this discussion paper, the transition from long-chain poly- and perfluorinated alkyl substances (PFASs) to fluorinated alternatives is addressed. Long-chain PFASs include perfluoroalkyl carboxylic acids (PFCAs) with 7 or more perfluorinated carbons, perfluoroalkyl sulfonic acids (PFSAs) with 6 or more perfluorinated carbons, and their precursors. Because long-chain PFASs have been found to be persistent, bioaccumulative and toxic, they are being replaced by a wide range of fluorinated alternatives. We summarize key concerns about the potential impacts of fluorinated alternatives on human health and the environment in order to provide concise information for different stakeholders and the public. These concerns include, amongst others, the likelihood of fluorinated alternatives or their transformation products becoming ubiquitously present in the global environment; the need for more information on uses, properties and effects of fluorinated alternatives; the formation of persistent terminal transformation products including PFCAs and PFSAs; increasing environmental and human exposure and potential of adverse effects as a consequence of the high ultimate persistence and increasing usage of fluorinated alternatives; the high societal costs that would be caused if the uses, environmental fate, and adverse effects of fluorinated alternatives had to be investigated by publicly funded research; and the lack of consideration of non-persistent alternatives to long-chain PFASs.

Reactivity of the uranium(IV) carbene complex [U(BIPM(TMS))(Cl)(μ-Cl)₂Li(THF)₂] (BIPM(TMS) = {C(PPh₂NSiMe₃)₂}) towards carbonyl and heteroallene substrates: metallo-Wittig, adduct formation, C-F bond activation, and [2 + 2]-cycloaddition reactions.

The reactivity of the uranium(IV) carbene complex [U(BIPM(TMS))(Cl)(μ-Cl)2Li(THF)2] (1, BIPM(TMS) = {C(PPh2NSiMe3)2}) towards carbonyl and heteroallene substrates is reported. Reaction of 1 with benzophenone proceeds to give the metallo-Wittig terminal alkene product Ph2C=C(PPh2NSiMe3)2 (2); the likely "UOCl2" byproduct could not be isolated. Addition of the bulky ketone PhCOBu(t) to 1 resulted in loss of LiCl, coordination of the ketone, and dimerisation to give [U(BIPM(TMS))(Cl)(μ-Cl){OC(Ph)(Bu(t))}]2 (3). The reaction of 1 with coumarin resulted in ring opening of the cyclic ester and a metallo-Wittig-type reaction to afford [U{BIPM(TMS)[C(O)(CHCHC6H4O-2)]-κ(3)-N,O,O'}(Cl)2(THF)] (4) where the enolate product remains coordinated to uranium. The reaction of PhCOF with 1 resulted in C-F bond activation and oxidation resulting in isolation of [U(O)2(Cl)2(μ-Cl)2{(μ-LiDME)OC(Ph)=C(PPh2NSiMe3)(PPh2NHSiMe3)}2] (5) along with [U(Cl)2(F)2(py)4] (6). The reactions of 1 with tert-butylisocyanate or dicyclohexylcarbodiimide resulted in the isolation of the [2 + 2]-cycloaddition products [U{BIPM(TMS)[C(NBu(t)){OLi(THF)2(μ-Cl)Li(THF)3}]-κ(4)-C,N,N',N''}(Cl)3] (7) and [U{BIPM(TMS)[C(NCy)2]-κ(4)-C,N,N',N''}(Cl)(μ-Cl)2Li(THF)2] (8). Complexes 2-8 have been variously characterised by single crystal X-ray diffraction, multi-nuclear NMR and FTIR spectroscopies, Evans method solution magnetic moments, variable temperature SQUID magnetometry, and elemental analyses.

15-deoxy-Δ12,14-prostaglandin J2 ameliorates endotoxin-induced acute lung injury in rats

Background A proinflammatory milieu emerging in the lung due to neutrophil accumulation and activation is a key in the pathogenesis of acute lung injury (ALI). 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2), one of the terminal products of the cyclooxygenase-2 pathway, is known to be the endogenous ligand of peroxisome proliferator-activated receptor γ (PPAR-γ) with multiple physiological properties. Growing evidence indicates that 15d-PGJ2 has anti-inflammatory, anti-proliferative, cytoprotective and pro-resolving effects. We investigated whether 15d-PGJ2 has a protective effect against endotoxin-induced acute lung injury in rats. Methods Twenty-four male Wistar rats were randomly assigned into four groups (n=6 per group): sham+vehicle group, sham+15d-PGJ2 group, LPS+vehicle group, and LPS+15d-PGJ2 group. The rats were given either lipopolysaccharide (LPS, 6 mg/kg intravenously) or saline, and pretreated with 15d-PGJ2 (0.3 mg/kg intravenously) or its vehicle (dimethyl sulphoxide) 30 minutes before LPS. Histological alterations, wet/dry weight (W/D) ratio and myeloperoxidase (MPO) activity as well as tumor necrosis factor (TNF)-α and cytokine-induced neutrophil chemoattractant-1 (CINC-1) levels were determined in lung tissues four hours after LPS injection. Immunohistochemical analysis for intercellular adhesion molecule-1 (ICAM-1) expression and Western blotting analysis for nuclear factor (NF)-κB p65 translocation and IκBα protein levels were also studied. Results 15d-PGJ2 pretreatment significantly attenuated LPS-induced lung injury, and reduced the increased W/D ratio, MPO activity, TNF-α, CINC-1 levels, and ICAM-1 expression in the lung. 15d-PGJ2 also suppressed the nuclear NF-κB p65 translocation and increased cytosolic IκBα levels. Conclusions 15d-PGJ2 protects against endotoxin-induced acute lung injury, most likely through the reduction of pro-inflammatory protein levels during endotoxemia subsequent to the inhibition of NF-κB activation.

Study on temporal and spatial evolution of China’s oil supply and consumption

To begin with, energy flow chart is used to analyze the status of China’s oil supply and consumption. Moreover, the temporal and spatial evolution of the oil production and oil products consumption in China is studied based on the gravity model. Finally, the decoupling index combined with the log mean Divisia index method is used to explore the contribution of the factors which influence terminal oil product consumption in China over the period 1991–2010. This paper draws the following results: (1) China’s net oil import dependency soared from 7.5 % in 1993 to 58.63 % in 2010. (2) The center of gravity for crude oil production and oil products consumption is an overall movement toward the southwest. (3) The economic activity effect is the critical factor in the growth of oil products consumption in China. However, industrial energy intensity effect plays the dominant role in decreasing oil products consumption. (4) The value of the decoupling index represented a re-coupling effect in 1996–1997 and 2003–2004. The other time interval showed weak decoupling effect.

Blockade of Alternative Complement Pathway in Dense Deposit Disease

A patient aged 17 with dense deposit disease associated with complement activation, circulating C3 Nef, and Factor H mutation presented with nephrotic syndrome and hypertension. Steroid therapy, plasma exchange, and rituximab failed to improve proteinuria and hypertension despite a normalization of the circulating sC5b9 complex. Eculizumab, a monoclonal antibody directed against C5, was used to block the terminal product of the complement cascade. The dose was adapted to achieve a CH50 below 10%, but proteinuria and blood pressure were not improved after 3 months of treatment.

A study of Fe(III)TPPCl encapsulated in zeolite NaY and Fe(III)NaY in the oxidation of n-octane, cyclohexane, 1-octene and 4-octene

The Fe(III)TPPCl (Fe(III)tetraphenylporphyrin chloride) complex was immobilized using the encapsulation method in order to entrap the complex inside the faujasite NaY zeolite to obtain FeTPP–NaY. This was achieved by adding the FeTPP as a template during the synthesis of NaY. The ICP results show that a 0.3 wt% loading of Fe was achieved and the XRD confirmed the faujasite Y structure. Further to this, a Fe–NaY zeolite was synthesized for the purpose of comparing it with FeTPP–NaY. The synthesized FeTPP–NaY and Fe–NaY were tested in the oxidation of n-octane, 1-octene, 4-octene and cyclohexane to oxygenates in the liquid phase using acetonitrile as a solvent, H2O2 and tert-butyl hydroperoxide in water as oxidants at 80 °C. Conversions of n-octane of 1.8 and 2.9 % and selectivities to terminal products of 13 and 8.8 % were achieved using FeTPP–NaY and Fe–NaY, respectively. Conversions of 1.4 and 1.8 % were achieved for 1-octene and 4-octene, respectively. A higher conversion of 18 % for cyclohexane was observed. These results show that cyclohexane is most reactive under these conditions and that the NaY matrix is not suitable for selective linear paraffin oxidation. Furthermore, leaching of Fe from the Fe–NaY was observed, even though the faujasite NaY structure was maintained as confirmed by XRD, while for FeTPP–NaY, the leaching of Fe was not observed.

Atmospheric Oxidation of Peroxyacetic Acid

The full reactive atmospheric oxidation profile of peroxyacetic acid under high NO conditions was examined using electronic structure calculations at various levels of theory. The three pathways resulting from the reaction of peroxyacetic acid with the hydroxyl radical were (1) addition of OH to the central carbon, (2) abstraction of the acidic hydrogen, and (3) abstraction of the methyl hydrogen. These pathways were followed to terminal product steps, the major products being acetic acid for pathway 1 and formaldehyde for pathways 2 and 3.

On ranking multiple touch-screen panel suppliers through the CTQ: applied fuzzy techniques for inspection with unavoidable measurement errors

The touch-screen panel (TSP) market has significantly brought up a great deal of business opportunities; in fact, it shows continuous growth in revenue, units, and area. Therefore, the high growth rate of the TSP market forces all the manufactures in the TSP supply chain to face a very competitive environment. The main purpose of this study is to provide a practical procedure for the manufacturers of the TSP terminal application products to rank their TSP suppliers. Via the critical-to-quality (CTQ) tree, CTQ is defined, and the index $$ C_{pm} $$ C p m is utilized to measure the CTQ. Since measurement errors are often unavoidable in the inspection phase, fuzzy theory is integrated into the $$ C_{pm} $$ C p m estimations. By the concept of fuzzy preference relation, a step-by-step procedure is provided for solving the TSP supplier selection problem. This study gives practicability for the real-life applications.

Kinetic model for reactions of indole under supercritical water gasification conditions

We developed a quantitative kinetics model for the homogeneous decomposition and gasification of indole in supercritical water at 550–650°C based on a reaction network with 17 separate reaction pathways. The model accurately describes the effects of time, temperature, and initial concentrations on the concentrations of intermediate products such as aniline, toluene, and benzene as well as the terminal gaseous products such as H2, CH4, and CO2. Modeling revealed that three steps are most important for H2 production. Ring-opening of indole to form aniline is the fastest such step during the first few minutes at 600°C, depletion of the large variety of gasifiable products dominates at times between 5 and 55min, and water gas shift is the main H2-producing reaction at longer times. The model also revealed that some of the potential pathways were kinetically insignificant at 600°C. Such paths included methanation, gasification of benzene, steam reforming of indole, and formation of CO, CO2, and C2H6 from intermediate products.

Tissue distribution of 35S-labelled perfluorobutanesulfonic acid in adult mice following dietary exposure for 1–5 days

Perfluorobutanesulfonyl fluoride (PBSF) has been introduced as a replacement for its eight-carbon homolog perfluorooctanesulfonyl fluoride (POSF) in the manufacturing of fluorochemicals. Fluorochemicals derived from PBSF may give rise to perfluorobutanesulfonic acid (PFBS) as a terminal degradation product. Although basic mammalian toxicokinetic data exist for PFBS, information on its tissue distribution has only been reported in one study focused on rat liver. Therefore, here we characterized the tissue distribution of PFBS in mice in the same manner as we earlier examined its eight-carbon homolog perfluorooctanesulfonate (PFOS) to allow direct comparisons. Following dietary exposure of adult male C57/BL6 mice for 1, 3 or 5d to 16mg 35S-PFBSkg−1d−1, both scintillation counting and whole-body autoradiography (WBA) revealed the presence of PFBS in all of the 20 different tissues examined, demonstrating its ability to leave the bloodstream and enter tissues. After 5d of treatment the highest levels were detected in liver, gastrointestinal tract, blood, kidney, cartilage, whole bone, lungs and thyroid gland. WBA revealed relatively high levels of PFBS in male genital organs as well, with the exception of the testis. The tissue levels increased from 1 to 3d of exposure but appeared thereafter to level-off in most cases. The estimated major body compartments were whole bone, liver, blood, skin and muscle. This exposure to PFBS resulted in 5–40-fold lower tissue levels than did similar exposure to PFOS, as well as in a different pattern of tissue distribution, including lower levels in liver and lungs relative to blood.

Fabrication of Flowerlike Vaterite Calcium Carbonate Crystal Aggregates by Self‐Assembly in Water/Ethanol Mixtures

AbstractVaterite calcium carbonate hierarchical structures with a flowerlike appearance have been successfully synthesized by means of a nanoparticle‐mediated self‐organization process in an ethanol/water mixed solution system under mild conditions without using any organic additives. A mechanism for the formation of vaterite crystal aggregates with flowerlike structures made of decussate “cigars” is presented. There are two points that play important roles in the regular organization of the terminal products: one is the concentration of carbonate, and the other is the volume ratio of ethanol/double‐distilled water. In view of the results, a nanoparticle‐mediated self‐organization process is helpful in controlling the aggregation‐driven formation of complex higher‐order‐structured materials and will provide new insights into biomineralization mechanisms. This study could provide an additional tool for designing advanced materials and could be used for the synthesis of more complex crystalline three‐dimensional structures.

Design and Implementation of Mathematical Simulation System in GNSS Signal Simulator

Global Navigation Satellite System (GNSS) signal simulator is one of the most important instruments for testing the function and performance of GNSS terminal products. It consists of a Mathematical Simulation System (MSS) and a Radio Frequency Signal Generator (RFSG). The MSS is responsible for generating the navigation message and observation data and then sending them to the RFSG in real time. The simulation accuracy of each part in the MSS determines that of the signal generated by the RFSG. In this paper, the function requirements of each module in MSS are analyzed firstly. Then the general framework of MSS is presented. At last, MSS developed in this paper is demonstrated and tested partly, the test results are compared with that of SimGEN software and STK. Taken as a whole, the MSS has complete functions and good performance. The MSS will hopefully apply to GNSS signal simulator.

Sequential administration of the high affinity CXCR4 antagonist BKT140 promotes megakaryopoiesis and platelet production

Platelets are the terminal differentiation product of megakaryocytes (MKs). Cytokines, such as thrombopoietin (TPO), are known to influence different steps in MK development; however, the complex differentiation and platelet localization processes are not fully understood. MKs express the receptor CXCR4 and have been shown to migrate in response to CXCL12 and to increase their platelet production. In this study, we studied the role of CXCR4 in platelet production with the high affinity CXCR4 antagonist, BKT140. Single and sequential administration of BKT140 significantly increased the number of MKs and haematopoietic progenitors (HPCs) within the bone marrow (BM). Increased megakaryopoiesis was associated with increased platelet production. Single and sequential administration of BKT140 also increased the number of HPCs in the blood. In a model of 5-fluorouracil-induced thrombocytopenia, BKT140 significantly reduced the severity and duration of thrombocytopenia and cytopenia when administered before and after chemotherapy. Our results demonstrated that the CXCR4 antagonist, BKT140, mediated unique beneficial effects by stimulating megakaryopoiesis and platelet production. These results provide evidence for the possible therapeutic use of BKT140 for modulating platelet numbers in thrombocytopenic conditions.

Direct flux and 15N tracer methods for measuring denitrification in forest soils

Estimates of denitrification are one of the key uncertainties in the terrestrial nitrogen (N) cycle, primarily because reliable measurements of this highly variable process—especially the production of its terminal product (N2)—are difficult to obtain. We evaluated the ability of gas-flow soil core and 15N tracer methods to provide reliable estimates of denitrification in forest soils. Our objectives were to: (1) describe and present typical results from new gas-flow soil core and in situ 15N tracer methods for measuring denitrification, (2) discuss factors that affect the relevance of these methods to actual in situ denitrification, and (3) compare denitrification estimates produced by the two methods for a series of sites in a northern hardwood forest ecosystem. Both methods were able to measure accumulations of N2 over relatively short (2–5 h) incubations of either unamended or tracer-amended intact soils. Denitrification rates measured by the direct flux soil core method were very sensitive to incubation oxygen (O2) concentration and decreased with increased O2 levels. Denitrification rates measured by the in situ 15N tracer method were very sensitive to the 15N content of the nitrate (NO3 −) pool undergoing denitrification, which limits the applicability of this method for quantifying denitrification in N-poor ecosystems. While its ability to provide accurate estimates of denitrification was limited, the 15N tracer method provided estimates of the short-term abiotic and biotic transformations of atmospheric N deposition to gas. Furthermore, results suggest that denitrification is higher and that N2O:N2 ratios are lower (<0.02) than previously thought in the northern hardwood forest and that short-term abiotic and biotic transformations of atmospheric N deposition to gas are significant in this ecosystem.

전자책 사용자만족도 영향요인에 대한 단말기유형의 조절효과

전자책단말기 유형은 크게 전용단말기와 범용단말기로 구분된다. 전자책단말기 시장의 경쟁이 격화되고 있지만 전용단말기와 범용단말기가 건전한 경쟁을 하면서 시장에 공존하는 것이 소비자와 기업에게 바람직한 상황이 될 수 있다. 이를 위하여 단말기유형별로 차별화된 전략으로 경쟁력을 확보하고 독자적인 시장을 만들어가는 것이 필요하다. 본 연구에서는 전자책단말기의 하드웨어품질과 소프트웨어품질을 독립변수로, 사용자만족도를 종속변수로, 단말기유형을 조절변수로 설정하여, 사용자만족도에 영향을 미치는 변수들의 영향력 정도가 단말기유형에 따라 어떻게 달라지는지 살펴보았다. 연구결과로서, 첫째 전자책단말기의 하드웨어품질과 소프트웨어품질은 모두 사용자 만족도에 통계적으로 유의한 영향을 미쳤다. 둘째, 전자책단말기의 하드웨어품질이 사용자만족도에 주는 영향력은 단말기유형에 따라 차이가 없지만, 소프트웨어품질이 사용자만족도에 주는 영향력은 단말기유형에 따라 유의한 차이가 있었다. 이러한 결과를 바탕으로, 전용단말기 제공업체는 범용단말기와 차별화된 제품을 내놓기 위하여 전자책뷰어의 품질을 높일 수 있는 전략을 수립할 필요가 있다. The terminals of e-Book(electronic Book) are classified into two types which consist of special-purpose terminal equipment and general-purpose terminal equipment. Although the terminal products inr the two types have had a strong race in the e-Book market each other, both enterprises and consumers want the two type to remain persistently with competition in good faith. Therefore, it is necessary for each type camps to find blue ocean by establishing differentiation strategies of each type. In this paper, we designed the research model that independent variables consist of hardware quality and software quality, dependent variable is user satisfaction, moderator variable is the terminal type. Through the research model, we investigated factors having a influence on the user satisfaction of the e-Book terminal that consists of hardware and software. In particular, we investigated if the degree of the influence is different between the two types. As a result, we got conclusions as followings. First, the quality of hardware and software in the terminal had significant influences on the user satisfaction. Second, the degree which the hardware quality has influenced user satisfaction was not different between the two types, but the degree which the software quality has influence on user satisfaction was different between the two types. As a implication of this result, we found that special-purpose terminal provider need to establish a strategies for raising the quality of e-Book viewer to provide different product from general-purpose terminal.

A descriptor for the relative propagation of the aromatic- and olefin-based cycles in methanol-to-hydrocarbons conversion on H-ZSM-5

The observed product distribution in methanol-to-hydrocarbons (MTH) catalysis can be rationalized based on the relative rates of propagation of the aromatic- and olefin-based cycles that operate on the zeolite catalyst. We report that the ratio of ethene to 2-methylbutane+2-methyl-2-butene (ethene/2MB) yield can be used to describe the propagation of aromatic and olefin methylation/cracking cycles. The co-reaction of 12C-ethene with 13C-dimethyl ether (DME) shows that the rate of DME conversion (1.62molC (molAls)−1) is ∼20 times faster than ethene conversion (0.08molC (molAls)−1), suggesting that ethene can be considered as terminal product for MTH at 623K. At iso-conversion conditions at 548K, propene is co-fed with DME to increase propagation of the olefin-based cycle and correspondingly a 1.7-fold decrease in the ethene/2MB yield is observed. Similarly, the co-reaction of toluene with DME increases propagation of the aromatic-based cycle and a 2.1-fold increase in the ethene/2MB yield is observed. The ethene/2MB yield also increased by a factor of 2 as DME conversion increased from 5% to 62%, which is consistent with the observed concurrent increase in selectivity to ethene and methylbenzenes. For the reaction of DME alone, increasing the temperature from 548K to 723K increases the propagation of the olefin-based cycle and a corresponding decrease in the ethene/2MB yield from 4.7 to 1.3 is also observed. The ethene/2MB yield varies systematically with feed composition, conversion, and temperature, showing that this ratio describes the relative propagation of the aromatic to olefin methylation/cracking cycles in MTH conversion on H-ZSM-5.

Operation Factors of Autotrophic Denitrification with Elemental Sulfur as Terminal Product

An anaerobic membrane bioreactor (UBF) with a total capacity of 3L was employed for treatment of sulfide and nitrate containing wastewater with elemental sulfur as terminal product. The effect of HRT and pH on substrate removal and elemental sulfur accumulation was researched when S/N ratio at 2.5. The influent concentration of S2-/HS-and NO3--N were 110mg•L-1and 20mg•L-1, respectively, during autotrophic denitrification. When HRT was between 7.41h and 6.83h and pH was between 6 and 7.5, HRT and pH has no effect on NO3--N and sulfide removal ratios, and at 97% and 100%, respectively, but elemental sulfur accumulation ratio was increased to 61% with HRT shorten. And low pH (pH at 7) was conducive to elemental sulfur accumulation with the ratio up to 62%. But further to reduce the pH would lead marginal increase in elemental sulfur accumulation ratio at 65%.