Ring-opening and Elimination Cooligomerization of Cyclic Carbonates and ε-Caprolactone

1 Introduction Cyclic carbonates e.g. ethylene- and propylene carbonate undergo ring-opening polymerization (ROP) at elevated temperatures (> 100 ℃) in the presence of initiators such as Lewis acids, bases, or transesterification catalysts to yield poly(ether carbonates) as outlined below.See Fig.1.1IntroductionCyclic carbonates e .g.ethylene-and propylene carbonate undergo ring-opening polymerization (ROP) atelevatedtemperatures ( >100 ℃) in the presence of initiators such as Lewis acid…     

Ring-opening and Elimination Cooligomerization of Cyclic Carbonates and e-Caprolactone

Cyclic carbonates e.g. ethylene- and propylene carbonate undergo ring-opening polymerization （ROP） at elevated temperatures （ 〉 100 ℃ ） in the presence of initiators such as Lewis acids, bases, or transesterification catalysts to yield poly（ether carbonates） as outlined below. See Fig. 1.     

A New Way of the Skeletal Metals Synthesis

1 Results Strongly disordered metals with the high chemical and catalytic activity are often called as skeletal metals.Usually for their preparation the metallides of d-metal (which afterwards will be left in the “skeleton“) and chemically active component(s) are firstly synthesized.Then the last one(s) is (are) removed by the leaching with aqueous solutions of alkalis or carbonates.However,this method sometime fails,first of all,for the reactions,which should be realized in non-aqueous conditions.In th...     

由风化壳淋积型稀土矿的浸出液制备大颗粒晶型稀土碳酸盐

Crystalline rare-earth (RE) carbonates having large particle size were prepared from the lixivium of weathered crust elution-deposited rare-earth ores using the precipitation method with ammonium bicarbonate as the precipitant. Their chemical composition was studied using elemental and thermogravimetric analyses (TGA), and their structure and morphology were characterized using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The results demonstrate that the crystalline rare-earth carbonate is a hydrated basic carbonate or oxycarbonate and not astable intermediate carbonate in the process of thermal decomposition. The particle size of crystalline rare-earth carbonates with large particle size is in the range of 50–200 μm. With an RE₂O₃ content of up to 95wt%, the quality of crystalline rare-earth carbonates is higher compared to the Chinese National Standard (GB/T 28882–2012). The quality of the product is superior to the Chinese National Standard.     

First discovery and characterizations of late Cretaceous seep carbonates from Xigaze in Tibet, China

Hydrocarbon seeps,widely occurring in continental margins,have become increasingly focused owing to their close relationships with gas hydrates,strong greenhouse gas methane,and biological resources in extreme environments.Ancient hydrocarbon seeps have already been recognized from Devonian to Quaternary strata worldwide based on seep carbonates or seep-related fossil chemosynthetic assemblages.However,seep-related deposits are rarely found from ancient strata in the mainland China.Here,we report the first discovery of an ancient seep deposit,specifically late Cretaceous seep carbonates from Xigaze in Tibet,China.Xigaze seep carbonates,occurring as nodules,are enclosed in upper Cretaceous turbidite strata in Xigaze forearc basin.These carbonates are composed of authigenic carbonate(56.2% on average),clastic quartz and feldspar(27.3% on average),and clay minerals(chlorite,illite and smectite,16.5% on average).Clotted micrites,peloids and framboid pyrites are frequently observed,all of which are common in modern seep carbonates.The carbonates have negative δ13 C values varying from 27.7‰ to 4.0‰(V-PDB),suggesting that thermogenic methane is the primary carbon source.Ce/Ce* values revised by eliminating La effects show no real Ce anomaly,indicating the carbonates were primarily precipitated in a weak reducing environment.Overall,these features provide unequivocal evidences that the seafloor of Xigaze forearc basin developed hydrocarbon seeps in late Cretaceous.     

Petrographic and geochemical characterization of seep carbonate from Alaminos Canyon,Gulf of Mexico

Seep carbonates were collected from the Alaminos Canyon lease area, Gulf of Mexico. The carbonates are present as slabs and blocks. Bivalve shell and foraminifer are the dominant bioclasts in carbonate. Pores are common and usually filled with acicular aragonite crystals. XRD investigation shows that aragonite is the dominate mineral （98%）. Peloids, clotted microfabirc and botryoidal aragonite are developed in carbonate and suggest a genesis linked with bacterial degradation of the hydrocarbons. The δ^13C value of bioclasts in carbonate is from -4.9‰ to -0.6‰, indicating that the carbon source is mainly from sea water as well as the small portion incorporation of the seep hydrocarbon. The microcrystalline and sparite aragonite shows the δ^13C value from -31.3‰ to -23.4‰, suggesting that their carbon is derived mainly from microbial degradation of crude oil. ^14C analyses give the radiocarbon age of about 10 ka. Rare earth elements （REE） analyses of the 5% HNO3-treated solution of the carbonates show that the total REE content of the carbonates is low, that is from 0.752 to 12.725 μg·g^-1. The shale-normalized REE patterns show significantly negative Ce anomalies. This suggests that cold seep carbonate is most likely formed in a relatively aerobic environment.     

Origin and nature of cold seep in northeastern Dongsha area, South China Sea: Evidence from chimney-like seep carbonates

The occurrence of seep carbonates is one of the characteristic features for cold seep sites at continental margins.The carbonates documented the venting history of methane-rich fluid.Compared to the chemoherm carbonates and carbonate pavements which formed on the sediment-water interface,chimney-like seep carbonates precipitated around fluid conduits below the sediment-water interface therefore better recording information of the past fluid flow and composition.Here the chimney-like seep carbonate samples from the northeastern Dongsha area of the South China Sea were studied to understand the origin and nature of the venting fluids and their potential relationship with gas hydrate deposits underneath the seafloor.Based on the occurrence,morphology,petrology,mineralogy and C-and O-isotope compositions,combined with present and past bottom water temperatures and the timing of methane release events,the oxygen isotopic fractionation between calcite and water were used to estimate the equilibriumδ18O values of the precipitating fluids.Theδ13C values ranging from 56.33‰to 42.70‰V-PDB and thus clearly show that the studied chimneys were mainly derived from biogenic methane oxidation.The calculated equilibriumδ18O values of the precipitating fluids ranged from 1.9‰0.3‰to 0.6‰0.3‰V-SMOW,with an average of 1.4‰0.3‰V-SMOW which is heavier than those of seawater even at the last glacial maximum.It is considered that the formation of chimney-like carbonates was closely related to methane hydrate dissociation in the area.The methane hydrates contributed as much as45.7%of water to the venting fluids.It is suggested that the climate and environmental changes(e.g.sea-level lowering,down-cutting canyons and mass wasting)are the major mechanisms maybe responsible for the destabilization of methane hydrates in the study area.The extensive occurrence of seep carbonates indicates that a large amount of the methane released from methane hydrate dissociation has been effectively captured and sequestered by microbial anaerobic oxidation of methane(AOM)before it escapes into the water column.     

A New Way of the Skeletal Metals Synthesis

1 Results Strongly disordered metals with the high chemical and catalytic activity are often called as skeletal metals.Usually for their preparation the metallides of d-metal (which afterwards will be left in the "skeleton") and chemically active component(s) are firstly synthesized.Then the last one(s) is (are) removed by the leaching with aqueous solutions of alkalis or carbonates.However,this method sometime fails,first of all,for the reactions,which should be realized in non-aqueous conditions.In the present work a "dry" way of the activated metals making,based on the method of selective vapor transporting reactions (SVTR) has been considered.The main idea of this method is the removal of the active component from a metallide to the vapor phase.For instance:     

Carbon isotopic record from Upper Devonian carbonates at Dongcun in Guilin,southern China,supporting the worldwide pattern of carbon isotope excursions during Frasnian-Famennian transition

Carbon isotopic composition of carbonates and or-ganic matter in sediments has been a powerful tool for deducing perturbations in the global carbon cycle which, in many cases, is observed together with the occurrence of biological mass extinctions[1]. The Frasnian-Famennian (F-F) mass extinction[2,3], so-called F-F event or bio-crisis, has been recognized as one of the five major bioevents of Phanerozoic time[4—7], and more than 60% of all Frasnian genera were eliminated[3,11]. This event …     

Re-Os isotopes and PGE geochemistry of black shales and intercalated Ni-Mo polymetallic sulfide bed from the Lower Cambrian Niutitang Formation, South China

The paleo oceanenvironmentalchangeduringthePrecambrian Cambriantransitionisakeyissuere latedtothecausesforanexplosiveradiationofdiffer entmetazoanphyladuringtheEarlyCambrianera .Thechemicalandisotopiccompositionsofmarinesed iments (carbonates ,phosphorites ,siliceousrocks ,andblackshales)recordthechangingcompositionandphysicalconditionsoftheseawaterinwhichtheserocksaccumulated .Organiccarbon richblackshalesfrommarineenvironmentsarecommonlyenrichedinanumberoftraceelementssuchasNi,Mo ,V ,Co ,…     

Calcium isotope fractionation and its controlling factors over authigenic carbonates in the cold seeps of the northern South China Sea

In this study, we analyzed stable calcium isotope results of authigenic carbonates from two cold seep areas of the Dongsha area and the Baiyun Sag in the northern South China Sea. The stable isotopes of carbon and oxygen as well as the mineral composition of authigenic carbonates were used to investigate control calcium isotope fractionation. The δ44/40Ca ratios of the southwestern Dongsha area samples ranged from 1.21‰ to 1.52‰ and the ratio of the Baiyun Sag sample was 1.55‰ of the SRM915a isotope standard. X-ray diffraction analysis showed that the carbonate samples consisted of dolomite, calcite and aragonite, with small amounts of high-Mg calcite and siderite. The δ13C values of the carbonates of the southwestern Dongsha area varied between δ49.21‰ and δ16.86‰ of the Vienna PeeDee Belemnite (VPDB) standard and the δ18O values ranged from 2.25‰ to 3.72‰ VPDB. The δ13C value of the Baiyun Sag sample was 2.36‰ VPDB and the δ18O value was 0.44‰ VPDB. The δ13C values of the carbonates of the southwestern Dongsha area revealed there is methane seeping into this area, with a variable contribution of methane-derived carbon. The sampled carbonates covered a range of δ13C values suggesting a dominant methane carbon source for the light samples and mixtures of δ13C values for the heavier samples, with possibly an organic or seawater carbon source. The δ18O values indicated that there is enrichment in 18O, which is related to the larger oxygen isotope fractionation in dolomite compared to calcite. The results of the Baiyun Sag sample exhibited normal seawater carbon and oxygen isotopic values, indicating that this sample is not related to methane seepage but instead to precipitation from seawater. The relatively high δ44/40Ca values indicated either precipitation at comparatively high rates in pore-water regimes with high alkalinity, or precipitation from an evolved heavy fluid with high degrees of Ca consumption (Raleigh type fractionation). The dolomite samples from the Dongsha area revealed a clear correlation between the carbon and calcium isotope composition, indicating a link between the amount and/or rate of carbonate precipitation and methane contribution to the bicarbonate source. The results of the three stable isotope systems, mineralogy and petrography, show that mineral composition, the geochemical environment of authigenic carbonates and carbon source can control the calcium isotope fractionation.     

Specific structural features of LnZrOx (Ln: La, Sm) mixed oxides prepared by different methods

LnZrOx(Ln: La, Sm) mixed oxides of Ln: Zr = 1 were prepared by different methods(complex polymerized method, sorption of cations on starch from aqueous salt solution and conventional co-precipitation with additional redispersion of precipitate by ultra sound) and calcined at 700–1300 °C. Their specific structural features and changes were studied and discussed. Various characterization methods were used such as X-ray diffraction,Electron microscopy, Fourier-transform infrared and Raman spectroscopy, UV–Vis spectroscopy, X-Ray absorption fine structure and X-ray photoelectron spectroscopy.The formation of pyrochlore structure occurred at 1100–1300 °C from fluorite-like pseudocubic phase ZrO_2 regardless the method of preparation. This phase had a block-like structure consisting of ZrO_2 nanocrystals stabilized by Ln cations and residual anions such as hydroxyls and carbonates. The desorption of such anions with heating already started at 900 °C and lead to local changes of Zr cations coordination to octahedral and to the formation of pyrochlore nanodomains inclusions within fluorite-like phase. The increased cation mobility and further elimination of anions caused by further heating was accompanied by the formation of bulk pyrochlore phase at 1100–1300 °C. Even after calcination at 1300 °C the local microheterogeneity as well as defects were identified at domains boundaries or sintered microstructure. These specific features of the formed pyrochlores depend on the method of preparation.     

Late Neoproterozoic to early Cambrian sulphur cycle-An isotopic investigation of sedimentary rocks from the Yangtze Platform

The sulphur cycle responds to changes in seawater chemistry, biological evolution and tectonic activity. We follow an isotopic approach in order to constrain the state of the ocean/atmosphere system during late Neoproterozoic and early Cambrian. For this purpose, a sedimentary succession deposited on the Yangtze Platform, South China, was analysed for its sulphur isotopic composition in different S-bearing phases. Redox changes were defined by the degree of pyritization (DOP) values in order to show variations in the oxygenation of the depositional environment. The sulphur isotopic composition of late Neoproterozoic to early Cambrian seawater sulphate ranges from +30‰ to +35‰ as evident from trace sulphate in unaltered carbonates and phosphorites. The isotopic composition for pyrite and organic sulphur varies between -16‰ and +23‰. The apparent sulphur isotopic fractionation between seawater sulphate and pyrite as well as organically bound sulphur varies between 7‰ and 50‰. This large fractionation, as well as its variability suggests a biological origin for pyrite and organically bound sulphur. The temporal evolution of different geochemical proxy signals is comparable for different successions across the Yangtze Platform.     

Indicators of δ13C and δ18O of gas hydrate-associated sediments

The analyses of δ13C and δ18O of gas hydrate-associated sediments from two cores on Hydrate Ridge in Cascadia convergent margin offshore Oregon, eastern North Pacific show the values of d 13C from -29.81‰ to -48.28‰ (PDB) and d 18O from 2.56‰ to 4.28‰ (PDB), which could be plotted into a group called typical carbonate minerals influenced by the methane in cold venting. Moreover, the values of d 13C and d 18O show a consistent trend in both cores from top to bottom with increasing of d 13C and decreasing of d 18O. This trend could be explained as an effect caused by the anaerobic oxidation of methane (AOM) in depth and the oxygen fraction during the formation of gas hydrate in depth together. These characteristics of d 13C and d 18O indicate that the gas hydrate-associated sediments are significantly different from the normal marine carbonates, and they are deeply influenced by the formation and evolution of gas hydrate. So, the distinct characteristics of d 13C and d 18O of gas hydrate-associated sediments could be undoubtedly believed as one of parameters to determine the presence of gas hydrates in other unknown marine sediment cores.     

也谈as引导的定语从句

as作为关系词既可以引导限制性定语从句 ,又可以引导非限制性定语从句。as可在定语从句中作主语、表语、宾语、定语和状语。一、as引导的非限制性定语从句 ,主要用于下列几种搭配中 :(1)such—as和suchas意为“像—这样的—” ,如 :SuchwomenasknewTom(ThosewomemwhoknewTom)thoughthewaschanming .认识Tom的女人都认为他很有魅力 (as作主语 )。Wehadhopedtogiveyouachancesuchasnobodyelseeverhad .我们想给你一次别人不曾有过的机会 (as作宾语 )。(2 )thesame—as—意为“和—相同的—” ,例如 :Ihavethesametroubleasyou .我有跟你一…     

关于多级火箭的最佳质量比(英文)

In 1955-1956, M. Vertregt introduced the problem about the least take-off weight of step-rockets and gave a matbematieal model of this problem as well as some calculations~[1]. In 1957, M. L, Williams followed up the study and pointed Out that G_(CN) and G_(TN) satisfied the following relation~[2] G_(CN)=[V_(CN)~((1))+V_(CN)~((2))]G_(TN)+V_(CN)~((3))G_n, thereby developing the mathematical model in [1]. For details see [2] (in which the significance of symbols, such as G_(CN) etc. was explained).     

P(AN-MMA)/TiO_2 Nano-composite Polymer Electrolyte by in-situ Polymerization

1 Introduction With the development of portable electric devices,polymer lithium ion batteries (PLiBs) have been widely used as the power sources because of their high energy density and safe property[1].P(AN-MMA) copolymer is a kind of cheap macromolecules easily dissolving in the polar solvents such as carbonate,it has been applied as gel polymer electrolyte in PLiBs.Here we prepare a kind of highly conductive nano-composite polymer electrolytes using the P(AN-MMA) copolymer incorporated with TiO2 nanoparticles as polymer matrix.The nano-composite polymer materials are prepared by an in-situ polymerization method.Nano-composite polymer electrolytes (NCPEs) are prepared by immersing the obtained porous P(AN-MMA)/TiO2 nano-composite polymer membranes in non-aqueous electrolyte.Their electrochemical characteristics were discussed here.     

Fatty-acids and their δ~(13)C characteristics of seep carbonates from the northern continental slope of Gulf of Mexico

Here we reported the fatty-acids and their δ13 C values in seep carbonates collected from Green Canyon lease block 185 (GC 185;Sample GC-F) at upper continental slope (water depth:～540 m),and Alaminos Canyon lease block 645 (GC 645;Sample AC-E) at lower continental slope (water depth:～2200 m) of the Gulf of Mexico.More than thirty kinds of fatty acids were detected in both samples.These fatty acids are maximized at C 16.There is a clear even-over-odd carbon number predominance in carbon number range.The fat...     

A TQCS-based Scheduling Approach for Manufacturing Grid

IntroductionsIn 2000, Ian Foster refined the definition [1] of Grid as“resource sharing and coordinated problem solving indynamic, multi institutional virtual organizations”. WithOGSA (Open Grid Service Architecture) [2] as its systemframework, OGSI (Open Grid Services Infrastructure) [3]as its implement mechanism and GT3 ( GlobusToolkit3.0) [4] as its development software, Grid is nowbecoming a newparadigm for solvinglarge scale distributedresource …     

Electrochemical reversibility of magnesium deposition-dissolution on aluminum substrates in Grignard reagent/THF solutions

The electrochemical behavior of magnesium deposition-dissolution on scratched aluminum foils in Grignard reagent/tetrahydrofuran (THF) solutions (1 mol L-1 EtMgBr/THF), which is regarded as a potential electrolyte of rechargeable magnesium batteries, was studied by using various methods such as cyclic voltammetry (CV), scanning electron microscopy (SEM), X-ray diffraction (XRD) and charge-discharge (deposition-dissolution) tests. The results present that the obtained magnesium deposits do not exhibit the morphology of dendrite and the Mg-Al alloy is not found on the surface of aluminum foils. The magnesium deposited on the aluminum substrates have excellent electrochemical cyclic performance in 1 mol L-1 EtMgBr/THF solution. The aluminum can be used as a candidate material of the negative current collector for rechargeable magnesium batteries.