固载型季铵盐离子液体催化合成环状碳酸酯:烷基链长及羟基的影响（英文）

CO_2是造成温室效应的主要原因,同时又是地球上储量最为丰富的可再生C1能源.因此,CO_2资源化受到了广泛关注.CO_2与环氧化物反应可合成环状碳酸酯,后者广泛用作极性溶剂、锂离子电池的电解液和聚碳酸酯中间体等.但是,由于CO_2的化学惰性,其反应需要高活性的催化剂.近年来,碱性金属、金属配合物及离子液体等均相催化剂被用于催化CO_2与环氧化物加成反应.其中,离子液体具有高热稳定性、低挥发性和结构可调性,得到了广泛研究.季铵盐、咪唑盐和季鏻盐等离子液体已经被证实具有较高的催化活性.然而,均相催化剂回收困难,而且产物需要进一步纯化.将离子液体固载化制备成非均相催化剂,可以实现简单的固/液分离.聚合物、SiO_2、SBA-15、氧化石墨烯和羧甲基纤维素等固载化催化剂已经广泛用于CO_2和环氧化物的环加成反应.虽然非均相催化剂显示了潜在的优势,但是催化活性较低的问题仍然亟待解决,尤其是在较温和的反应条件下.因此,通过催化剂分子结构设计以提高催化性能,成为目前的研究热点.本文提出在催化活性基团和载体之间引入长烷基链,增加催化活性位点与反应物的接触面积,同时引入助催化的羟基,通过长链与羟基的协同作用,提高非均相催化剂活性.本文合成了羟基功能化长柔性链季铵化聚苯乙烯微球非均相催化剂([AHTAPC-PS]X,X=Cl,Br,I),用于催化CO_2与环氧化物的环加成反应,并与不含羟基的长烷基链季铵盐离子液体非均相催化剂([TAPB-PS]Br)及短烷基链季铵盐离子液体非均相催化剂([TMA-PS]X)的催化性能进行了对比.考察了固载后的离子液体烷基链长及侧链羟基对催化性能的影响,并通过实验和密度泛函理论计算研究了催化机理.红外光谱、扫描电镜和能量散射谱结果充分证明了季铵盐非均相催化剂的成功合成;热重测试表明,此类催化剂具有可以满足反应需求的热稳定性.密度泛函理论计算结果显示,与短烷基链非均相催化剂相比,长烷基链非均相催化剂的阴离子负电性更强,同时羟基与环氧化合物的氧原子之间存在强的氢键作用.羟基形成的氢键可以增加环氧化物的C–O键长,同时强负电的阴离子更加容易攻击β-碳原子,促进环氧化物开环.另外,长烷基链结构使得卤素阴离子具有与反应物更大的接触范围,因此提高了反应活性.当采用短烷基链季铵盐非均相催化剂时,环氧丙烷(PO)与CO_2环加成反应生成碳酸丙烯酯(PC)的产率仅为70.9%,而采用长烷基链季铵盐非均相催化剂时产率可达91.4%(135°C,1.5 MPa,3 h),进一步加入助催化的羟基,则PC产率可提高到98.5%.此外,含羟基的长烷基季铵盐非均相催化剂在温和条件下也具有较高的催化活性(100°C,1.5 MPa,3 h,PC产率78.4%),该催化剂同时具有较高的循环稳定性(10次循环后,PC产率≥96%,选择性≥99%).综上所述,该催化剂具有优异的综合性能,展现了良好的工业应用前景.

High-performance Zn-graphite battery based on LiPF6 single-salt electrolyte with high working voltage and long cycling life

Zinc-ion batteries(ZIBs) are promising alternative energy storage devices to lithium-ion batteries owing to the merits of large abundance,high theoretical capacity,and environmental friendliness.However,critical challenges including low working voltage(below 2 V),low energy density as well as dendrites formation during long cycling caused by aqueous ZIB systems still hinder their practical applications.Herein,a high-voltage Zn-graphite battery(ZGB) based on a non-zinc ion single-salt electrolyte(2.5 M LiPF6 in carbonate solvent) is developed.Moreover,we surprisingly found that Zn^(2+) is dissolved in the LiPF6 single-salt electrolyte during resting and discharging processes,thus enabling reversible Zn plating/stripping mechanism on the Zn foil anode in the ZGB over the voltage window of 1.0-3.1 V.As a result,the ZGB achieves long-term cycling performance with a capacity retention of ~100% for over1200 cycles at 3 C and high Coulombic efficiency of ~100% in 1.0-3.1 V with no dendrites formation.Moreover,the ZGB exhibits a high working voltage of up to 2.2 V,thus contributing to both high energy density(up to 210 Wh kg^(-1)) and high power density(up to 1013 W kg^(-1)),superior than most reported ZIBs.

Observations of contrasted glacial-interglacial dissolution of foraminifera above the lysocline in the Bay of Bengal,northeastern Indian Ocean

Site U1446(19°50’N,85°44’E,at water depth 1430 m)was drilled during Expedition 353(Indian monsoon rainfall)of the International Ocean Discovery Program(IODP).It is located in the Mahanadi offshore basin,on the northern Bay of Bengal.Sedimentation rates and contents of biocarbonates are high at this relatively shallow site.Using a micropaleontological approach,we examined planktonic and benthic foraminifera in the upper around 40 m of this site,spanning the last around 190 ka.A striking feature of the foraminiferal record is the occurrence of strong but varying dissolution although the site is located well above the modern lysocline.Such strong dissolution has never been reported in this area.We estimated the flux of foraminifera and quantified the ratio of benthic foraminifera over total foraminifera(benthic/total foraminifera)along with the foraminifer fragmentation index in order to characterize past changes in this above-lysocline dissolution.This study reveals a clear glacialinterglacial contrast,with a stronger dissolution during marine isotope stages(MISs)1 and 5 than during MISs 2–4 and 6.Such a difference in preservation is likely to have a strong impact on geochemical proxies measured on foraminifera.Our new observations call for an in-depth study of the causes of such above-lysocline dissolution in the region,and an evaluation of its impact on the foraminifera-based proxies used for paleoenvironmental reconstruction.

Miocene paleoenvironmental evolution based on benthic foraminiferal assemblages in the Lufeng Sag, northern South China Sea

The Miocene epoch marks the most crucial period during the Cenozoic cooling trend, characterized by the Middle Miocene Climatic Optimum(MMCO) and a series of short–lived cooling events(Miocene isotope events).To understand the paleoenvironmental evolution along the shallow water shelf in the South China Sea during the Miocene, the benthic foraminiferal assemblage and total organic carbon content(TOC) were analyzed at Hole LF14 located in the Lufeng Sag, northern South China Sea. Three benthic foraminiferal assemblages(e.g., the Uvigerina spp. assemblage, the Cibicides spp. assemblage, and the Cibicidoides spp. assemblage), corresponding to different watermass conditions, were recognized based on Q–mode factor analysis. Early studies suggested that Hole LF14 was deposited under semienclosed bay, middle to outer shelf or even upper bathyal environment during ～18.7–4.53 Ma. The dominant Uvigerina spp. assemblage was characterized by low diversity and shallow infaunal to infaunal species, indicating a warm, low–oxygenation and eutrophic conditions since the Early Miocene to MMCO(～18.7–14.24 Ma). An abrupt sea level drop and significant faunal changes were recorded during 14.24–13.41 Ma, suggesting development of the East Antarctic Ice Sheets, which resulted in a drop of sea level and change in benthic foraminiferal assemblages along the shallow water shelf. Beyond the Uvigerina spp.assemblage, the Cibicides spp. assemblage became important during the middle–late Middle Miocene(14.24–11.54 Ma). This assemblage was dominated by epifaunal species with relative high diversity, suggesting high–energy, high–oxygenation and oligotrophic conditions with episodic supply of organic food. The dominant Cibicidoides spp. assemblage with high diversity, indicates a mesotrophic conditions with relative high–oxygen content during the Late Miocene to Pliocene(11.54–4.53 Ma). The appearance and continuous occurrence of Ammonia spp. and Pseudorotalia spp. since 10.02 Ma, may reflect the influence of the Kuroshio Current.

WiFace:A Secure GeoSocial Networking System Using Wi-Fi Based Multihop MANET

A number of mobile Online Social Networking （OSN） services have appeared in the market in recent times. While most mobile systems benefit greatly from cloud services, centralized servers and communications infrastructure is not always available. Nor are location-based services offered to mobile devices without GPS. To take advantage of cloud and to address these problems, a Wi-Fi based multihop networking system called MoNet is proposed. On top of MONET we propose a privacy-aware geosocial networking service called WiFace. Where there is no infrastructure, a distributed content sharing protocol significantly shortens the relay path, reduces conflicts, and improves data availability. Furthermore, a security mechanism is developed to protect privacy. Comprehensive experiments performed on MoNet show that the system is more than sufficient to support social networking and even audio and video applications.

Recovery of cathode copper and ternary precursors from CuS slag derived by waste lithium-ion batteries:Process analysis and evaluation

The efficient and environmentally friendly recycling technology of waste residue that including abundant heavy metal produced during the recovery of lithium batteries has become a research hotspot.Herein,a novelty process of acid leaching-selective electrodeposition-deep impurity removal-regeneration was proposed to recovery of the CuS slag,which has been efficient transferred to high purity cathode copper and commercially available ternary precursors.Copper cathode with a purity of 99.67%was prepared under electrochemical reaction conditions at-0.55 V for 2 h.A novel impurity remover-Mn powder,which was used to remove the residual impurities and as a feedstock for the ternary precursor.Finally,NCM523 was regenerated by co-precipitation.The process is superior to the traditional process in economy,energy consumption,CO_(2)emissions,product purity and process duration.This study provides a new approach for solid waste recovery and precious metal enrichment.

Utilizing synergistic effects of bifunctional polymer hydrogel PAM-PAMPS for selective capture of Pb(Ⅱ)from wastewater

The preparation of hydrogel adsorbents with admirable performance for efficient selective remove Pb(Ⅱ)in complex wastewater still remains a great challenge.Herein,a novel bifunctional modified polymer hydrogel PAM-PAMPS was prepared by crosslinking acrylamide(AM)and 2-acrylamido-2-methylpropanesulfonic acid(AMPS).Compared with PEG,PAA and PAMPS,PAM-PAMPS exhibited both the maximum adsorption capacity of Pb(Ⅱ)(541.90 mg/g)and satisfactory selectivity for Pb(Ⅱ)in multiple heavy metal ions coexistence solutions.Various characterizations indicated that–SO3H and–NH2as active sites on PAM-PAMPS occur the synergistic effects of ion-exchange and coordination with Pb(Ⅱ)during the adsorption process,respectively.The adsorption energy Ead(PAM-PAMPS)obtained from density functional theory(DFT)calculations was lower than the other three hydrogels,manifesting that PAMPAMPS formed the most stable complex with Pb(Ⅱ),which further demonstrated that Pb(Ⅱ)preferred to combine with PAM-PAMPS to selective capture of Pb(Ⅱ).The practice utilization of PAM-PAMPS was assessed by wastewater of electroplate containing Pb(Ⅱ).Meanwhile,the removal ratio of PAM-PAMPS was maintained at about 89%after 4 adsorption-desorption cycles.This study establishes a new and effective idea for the design and fabrication of bifunctionalized modified polymer hydrogels.

Feasible fabrication of o-phenanthroline-based polymer adsorbent for selective capture of aqueous Ag(Ⅰ)

Devising a desirable adsorbent for efficiently selective capture of Ag(Ⅰ) from wastewater has attracted much attention but faced with huge challenges. Herein, a novel linear o-phenanthroline-based polymer L-PRL was prepared via chemical oxidative polymerization for the adsorption of Ag(Ⅰ). The maximum adsorption capacity for Ag(Ⅰ) by L-PRL is 325.8 mg/g at pH 0. In addition, L-PRL owes ascendant selectivity for Ag(Ⅰ) from aqueous solutions containing various interfering metal ions of Pb(Ⅱ), Co(Ⅱ), Ni(Ⅱ), Cd(Ⅱ)and Fe(Ⅲ). Multiple characterizations of FT-IR and XPS uncover that the N groups on L-PRL act as adsorption sites to coordinate with Ag(Ⅰ). Density functional theory(DFT) calculations further evidence the mechanism that L-PRL is provided with the admirable adsorptivity and selectivity for Ag(Ⅰ). It is mainly attributed to the most stable complexes of L-PRL with Ag(Ⅰ), which possesses shortest Ag-N bond length compared with other heavy metal ions. Furthermore, 93.5% of initial adsorption capacity is reserved after four continuous regeneration cycles, indicating that L-PRL is equipped with superior recyclability and durability, and L-PRL is capable of removing Ag(Ⅰ) in low-concentration actual Ag(Ⅰ)-containing wastewater completely. This study shed light on the rational design of polymer adsorbents and in-depth insight into selective removal of aqueous Ag(Ⅰ).

tsrCert:Traceable Self-Randomization Certificate and Its Application to Blockchain Supervision

Traditional public key infrastructure(PKI)only provides authentication for network communication,and the standard X.509 certificate used in this architecture reveals the user’s identity.This lack of privacy protection no longer satisfies the increasing demands for personal privacy.Though an optimized anonymous PKI certificate realizes anonymity,it has the potential to be abused due to the lack of identity tracking.Therefore,maintaining a balance between user anonymity and traceability has become an increasing requirement for current PKI.This paper introduces a novel traceable self-randomization certificate authentication scheme based on PKI architecture that achieves both anonymity and traceability.We propose a traceable self-randomization certificate authentication scheme based on the short randomizable signature.Specifically,certificate users can randomize the initial certificate and public key into multiple anonymous certificates and public keys by themselves under the premise of traceability,which possesses lower computational complexity and fewer interactive operations.Users can exhibit different attributes of themselves in different scenarios,randomizing the attributes that do not necessarily need to be displayed.Through security and performance analysis,we demonstrate the suitability of the improved PKI architecture for practical applications.Additionally,we provide an application of the proposed scheme to the permissioned blockchain for supervision.

Tracing the Methane Events by Stable Carbon Isotopes of Benthic Foraminifera at Glacial Periods in the Andaman Sea

Stable isotopes of carbon and oxygen variations in foraminiferal shells have been widely used in paleo-environment studies.However,studies about the shells of benthic foraminifera in methanehydrate-bearing sediments as reliable geochemical proxies to reconstruct the potential methane release events in the geologic past are rare.In this study,we present the stable carbon and oxygen isotopes of fossil benthic foraminifera including one epifaunal species(Cibicidoides wuellerstorfi)and two infaunal species(Bulimina mexicana and Uvigerina peregrina)from the Site U1447 of IODP 353 Expedition to trace methane events in the Andaman Sea,where one of the thickest and deepest gas hydrate stability zones was discovered.Theδ^(13)C values of benthic foraminifera show that there are eight distinct intervals with negative values in the last~10 Myr,interpreted as a record of long-term fluctuations in methane emission.Six of these methane events occurred during the glacial sea-level lowstands in the last~1.1 Myr.We,therefore,infer that the trigger mechanism for these events might be the hydrate destabilization caused by sea level fall.The methane events that occurred at~2.11 and~5.93 Ma are more likely related to the sudden changes in sedimentation,either slide events or marked variations in sedimentation rate.

Distribution,ecology,and oxygen and carbon isotope characteristics of modern planktonic foraminifers in the Makarov Basin of the Arctic Ocean

The Arctic region, with magnificent ice cover on the surface of the Arctic Ocean and adjacent seas, is not only extremely sensitive to but also has strong amplification effects on climate change. Observations during the past decades have documented substantial retreat and thinning of the Arctic sea-ice cover, a process that is accelerating. Its feedback and impact on the global climate has become an important subject of current climate change research. Calcite tests of planktonic foraminifers are major constituents in pelagic sediments, and they provide valuable materials for the reconstruction of past oceanographic conditions. However, research is still sparse in the Arctic sea area because of limited availability of the materials for investigation. Here, we present a study of modern foraminifers from the plankton tow samples taken in the Makarov Basin of the Arctic Ocean during the fourth Arctic expedition of China. We have analyzed ecological information stored in the modern planktonic foraminifers and in their stable isotope signals, and established a relationship between the distribution of the main taxa and the environment. Our main observations are as follows:(1) in the Makarov Basin, the polar species Neogloboquadrina pachyderma(sinistral coiling) dominates the [150 lm planktonic foraminiferal assemblages.(2) The planktonic foraminifers live mainly in the upper halocline at a water depth of 50–100 m and less in the depth interval of 100–200 m.(3) Temperature change in the halocline can affect the absolute abundance of planktonic foraminifers and their distribution in the water column. The warmer halocline is more favorable to the development of planktonic foraminifers.(4) A lighter d18O value(2.11 %) of N. pachyderma(sin.) is recorded in the depth interval of 100–200 m, which is likely related to the isotopically light brines separated out during sea ice freezing. The relatively heavy d18O value(1.68 %–2.68 %, average 2.27 %) in the depth interval of 50–100 m may be influenced by the low salinity water with the relatively heavy d18O value formed during the sea-ice melting in the surface layer.