基于N掺杂Ti_(3)C_(2)MXene量子点的荧光探针用于Hg2+和S2-的传感检测

基于N掺杂Ti_(3)C_(2) MXene量子点(N-Ti_(3)C_(2) MQDs)荧光探针和配位相互作用,构建了一种检测Hg^(2+)和S^(2-)的“开-关-开”型荧光传感新方法.研究发现,制备的N-Ti_(3)C_(2) MQDs发射蓝色荧光(λem=440 nm),荧光量子产率为15.7%.Hg^(2+)与N-Ti_(3)C_(2) MQDs表面的—NH2,—COOH,—OH等官能团产生选择性配位作用,导致N-Ti_(3)C_(2) MQDs体系荧光猝灭.当加入S^(2-)后,由于S^(2-)与Hg^(2+)之间强的结合力,形成HgS沉淀,从而使N-Ti_(3)C_(2) MQDs体系荧光恢复.基于该原理,构建了一种“开-关-开”型荧光传感方法,实现了对Hg^(2+)和S^(2-)的定量检测.N-Ti_(3)C_(2) MQDs探针的荧光强度与Hg^(2+)浓度在0.02~200μmol/L范围内呈良好线性关系,检出限为10 nmol/L(S/N=3);与S^(2-)浓度在0.07~150μmol/L范围内呈良好线性关系,检出限为30 nmol/L(S/N=3).该方法具有成本低、操作简单、灵敏度高和选择性好等特点,并可用于水样中Hg^(2+)和S^(2-)的检测.

一种具有识别Hg^(2+)和ClO^(-)荧光探针的设计和应用

设计合成了一种含双酯基的1,2,3-三氮唑化合物,与罗丹明B酰肼结合生成了具有“开-关”性质的荧光探针(简称L_(2)),应用光谱学表征了L_(2)的物理化学参数。L_(2)分别在DMF/Tris-HCl(1:1,v/v,pH=6.0,20μmol/L)和MeOH(20μmol/L)溶液中对Hg^(2+)和ClO^(-)显示出高选择性和灵敏性;利用荧光和紫外光谱分别测定了L_(2)对19种金属离子和14种阴离子的光学性能。实验表明,Hg^(2+)和ClO^(-)的存在使得L_(2)在585 nm和576 nm均有一个新的发射峰出现;同时伴随着荧光强度明显的增强,溶液体系发生了裸眼能识别的显色变化,表明Hg^(2+)可以将罗丹明分子的酰肼闭环结构转换为开环结构,并以1:2的比例方式生成了一种新配合物,这也被质谱、工作曲线、核磁滴定和TD-DFT计算的结果所证实;L_(2)对Hg^(2+)和ClO^(-)的检测限分别为7.45 nmol/L和0.67μmol/L。此外,生物活性测定显示L_(2)对HeLa细胞有非常低的毒性,并且可用于HeLa细胞中Hg^(2+)和ClO^(-)的细胞成像,表明L_(2)在体内可进行微测定Hg^(2+)和ClO^(-)的巨大潜力。

1,3-氧硫戊环为受体的Hg^(2+)荧光探针的设计、合成及性能

Hg^(2+)是毒性最强的重金属离子之一,会造成空气、土壤和水的污染,严重损害人体健康,开发有效的分析方法检测环境体系中的Hg^(2+)尤为重要。荧光探针因其灵敏度高、选择性好、响应速度快、可实时在线检测等优点,已广泛应用于Hg^(2+)检测。以Hg^(2+)促进硫代缩醛的去保护反应设计合成了一种全新的以1,3-氧硫戊环为受体的开启型Hg^(2+)荧光探针[2-(pyren-1-yl)-1,3-oxathiolane,POX],通过^(1)H NMR、^(13)C NMR和HRMS对POX结构进行表征,考察了POX在CH_(3)CH_(2)OH/H_(2)O中对Hg^(2+)的选择性、竞争性、浓度滴定、pH滴定、时间依赖性、检出限和识别机理等。研究结果表明,POX可在较宽的pH范围内对Hg^(2+)快速识别,并表现出高度的选择性和灵敏度;向POX中加入Hg^(2+)后,在386 nm处出现明显的荧光发射峰,表明POX对Hg^(2+)呈现出显著的荧光“开启”效应,其识别过程几乎不受其他金属离子干扰;荧光滴定实验表明POX在Hg^(2+)浓度为0~6.5μmol·L^(-1)范围内具有良好的线性响应(R^(2)=0.9994),检出限为0.168μmol·L^(-1),在实际水样中检测Hg^(2+)的RSD小于2.92%。由于POX合成简单、原料易得且pH适用范围较广,可作为定性和定量检测环境中Hg^(2+)的潜在工具。

氨基酸基氮掺杂荧光碳点的制备及饮料中Hg^(2+)的检测

汞离子是一种高毒性的重金属污染物,人体摄入后会带来健康危害,因此控制食品中的汞离子含量非常重要。以柠檬酸为碳源,不同的氨基酸为氮源掺杂,采用一步水热法制备高性能荧光的碳点(CDs),探究不同氨基酸基氮掺杂对碳点荧光量子产率(QY)的影响,以及这些氨基酸基氮掺杂碳点对汞离子的响应。结果显示,不同氨基酸的碳链长度和官能团对CDs的QY有一定的影响。Hg^(2+)能高效猝灭以甘氨酸(Gly)为氮源掺杂的Gly-CDs的荧光,Gly-CDs具有良好的荧光稳定性,在优化的试验条件下,用于Hg^(2+)检测的线性范围为0.00~7.00μmol/L和8.00~60.00μmol/L,检出限为0.20μmol/L。据此构建的荧光探针用于检测实际饮料样品中的Hg^(2+),回收率在90.08%~107.90%。该方法简便、快速、灵敏、适用于饮料中Hg^(2+)的测定。

Delving into the dissimilarities in electrochemical performance and underlying mechanisms for sodium and potassium ion storage in N-doped carbon-encapsulated metallic Cu_(2)Se nanocubes

The large volumetric variations experienced by metal selenides within conversion reaction result in inferior rate capability and cycling stability,ultimately hindering the achievement of superior electrochemical performance.Herein,metallic Cu_(2)Se encapsulated with N-doped carbon(Cu_(2)Se@NC)was prepared using Cu_(2)O nanocubes as templates through a combination of dopamine polymerization and hightemperature selenization.The unique nanocubic structure and uniform N-doped carbon coating could shorten the ion transport distance,accelerate electron/charge diffusion,and suppress volume variation,ultimately ensuring Cu_(2)Se@NC with excellent electrochemical performance in sodium ion batteries(SIBs)and potassium ion batteries(PIBs).The composite exhibited excellent rate performance(187.7 mA h g^(-1)at 50 A g^(-1)in SIBs and 179.4 mA h g^(-1)at 5 A g^(-1)in PIBs)and cyclic stability(246,8 mA h g^(-1)at 10 A g^(-1)in SIBs over 2500 cycles).The reaction mechanism of intercalation combined with conversion in both SIBs and PIBs was disclosed by in situ X-ray diffraction(XRD)and ex situ transmission electron microscope(TEM).In particular,the final products in PIBs of K_(2)Se and K_(2)Se_(3)species were determined after discharging,which is different from that in SIBs with the final species of Na_(2)Se.The density functional theory calculation showed that carbon induces strong coupling and charge interactions with Cu_(2)Se,leading to the introduction of built-in electric field on heterojunction to improve electron mobility.Significantly,the theoretical calculations discovered that the underlying cause for the relatively superior rate capability in SIBs to that in PIBs is the agile Na~+diffusion with low energy barrier and moderate adsorption energy.These findings offer theoretical support for in-depth understanding of the performance differences of Cu-based materials in different ion storage systems.

In situ luminescence measurements of GaN/Al_(2)O_(3) film under different energy proton irradiations

Ion beam-induced luminescence(IBIL) experiments were performed to investigate the in situ luminescence of GaN/Al_(2)O_(3) at varying ion energies,which allowed for the measurement of defects at different depths within the material.The energies of H^(+)were set to 500 keV,640 keV and 2 MeV,the Bragg peaks of which correspond to the GaN film,GaN/Al_(2)O_(3) heterojunction and Al_(2)O_(3) substrate,respectively.A photoluminescence measurement at 250 K was also performed for comparison,during which only near band edge(NBE) and yellow band luminescence in the GaN film were observed.The evolution of the luminescence of the NBE and yellow band in the GaN film was discussed,and both exhibited a decrease with the fluence of H^(+).Additionally,the luminescence of F centers,induced by oxygen vacancies,and Cr^(3+),resulting from the ^(2)E →^(4)A_(2) radiative transition in Al_(2)O_(3),were measured using 2 MeV H^(+).The luminescence intensity of F centers increases gradually with the fluence of H^(+).The luminescence evolution of Cr^(3+)is consistent with a yellow band center,attributed to its weak intensity,and it is situated within the emission band of the yellow band in the GaN film.Our results show that IBIL measurement can effectively detect the luminescence behavior of multilayer films by adjusting the ion energy.Luminescence measurement can be excited by various techniques,but IBIL can satisfy in situ luminescence measurement,and multilayer structural materials of tens of micrometers can be measured through IBIL by adjusting the energy of the inducing ions.The evolution of defects at different layers with ion fluence can be obtained.

Investigations on MoS_(2)plasma by infra-red pulsed laser irradiation in high vacuum

MoS_(2)targets were irradiated by infra-red(IR)pulsed laser in a high vacuum to determine hot plasma parameters,atomic,molecular and ion emission,and angular and charge state distributions.In this way,pulsed laser deposition(PLD)of thin films on graphene oxide substrates was also realized.An Nd:YAG laser,operating at the 1064 nm wavelength with a 5 ns pulse duration and up to a 1 J pulse energy,in a single pulse or at a 10 Hz repetition rate,was employed.Ablation yield was measured as a function of the laser fluence.Plasma was characterized using different analysis techniques,such as time-of-flight measurements,quadrupole mass spectrometry and fast CCD visible imaging.The so-produced films were characterized by composition,thickness,roughness,wetting ability,and morphology.When compared to the MoS_(2)targets,they show a slight decrease of S with respect to Mo,due to higher ablation yield,low fusion temperature and high sublimation in vacuum.The pulsed IR laser deposited Mo Sx(with 1<x<2)films are uniform,with a thickness of about 130 nm,a roughness of about 50 nm and a higher wettability than the MoS_(2)targets.Some potential applications of the pulsed IR laser-deposited Mo Sx films are also presented and discussed.

Co-doped BaFe_(2)As_(2) Josephson junction fabricated with a focused helium ion beam

Josephson junction plays a key role not only in studying the basic physics of unconventional iron-based superconductors but also in realizing practical application of thin-film based devices,therefore the preparation of high-quality iron pnictide Josephson junctions is of great importance.In this work,we have successfully fabricated Josephson junctions from Co-doped BaFe_(2)As_(2)thin films using a direct junction fabrication technique which utilizes high energy focused helium ion beam(FHIB).The electrical transport properties were investigated for junctions fabricated with various He^(+)irradiation doses.The junctions show sharp superconducting transition around 24 K with a narrow transition width of 2.5 K,and a dose correlated foot-structure resistance which corresponds to the effective tuning of junction properties by He^(+)irradiation.Significant J_c suppression by more than two orders of magnitude can be achieved by increasing the He^(+)irradiation dose,which is advantageous for the realization of low noise ion pnictide thin film devices.Clear Shapiro steps are observed under 10 GHz microwave irradiation.The above results demonstrate the successful fabrication of high quality and controllable Co-doped BaFe_(2)As_(2)Josephson junction with high reproducibility using the FHIB technique,laying the foundation for future investigating the mechanism of iron-based superconductors,and also the further implementation in various superconducting electronic devices.

Hierarchically Structured Nb_(2)O_5 Microflowers with Enhanced Capacity and Fast-Charging Capability for Flexible Planar Sodium Ion Micro-Supercapacitors

Planar Na ion micro-supercapacitors(NIMSCs) that offer both high energy density and power density are deemed to a promising class of miniaturized power sources for wearable and portable microelectron-ics. Nevertheless, the development of NIMSCs are hugely impeded by the low capacity and sluggish Na ion kinetics in the negative electrode.Herein, we demonstrate a novel carbon-coated Nb_(2)O_5 microflower with a hierarchical structure composed of vertically intercrossed and porous nanosheets, boosting Na ion storage performance. The unique structural merits, including uniform carbon coating, ultrathin nanosheets and abun-dant pores, endow the Nb_(2)O_5 microflower with highly reversible Na ion storage capacity of 245 mAh g^(-1) at 0.25 C and excellent rate capability.Benefiting from high capacity and fast charging of Nb_(2)O_5 microflower, the planar NIMSCs consisted of Nb_(2)O_5 negative electrode and activated car-bon positive electrode deliver high areal energy density of 60.7 μWh cm^(-2),considerable voltage window of 3.5 V and extraordinary cyclability. Therefore, this work exploits a structural design strategy towards electrode materials for application in NIMSCs, holding great promise for flexible microelectronics.

Carrageenan Fiber Prepared by a New Process Route of Ba^(2+)Ion Pre-Crosslinking in the Spinning Solution

Ba^(2+)pre-crosslinked carrageenan fiber(Ba/CAF)was prepared by adding a small amount of Ba^(2+) to the carrageenan(CA)solution as the spinning solution.Ba/CAF-n/A,Ba/CAF-n/B and Ba/CAF-n/C were prepared with ethanol solution(combine A),high concentration BaCl_(2)solution(combine B)and low concentration BaCl_(2)solution(combine C),as coagulation bath and stretch bath,respectively.The combination of coagulation bath and stretch bath suitable for Ba^(2+) pre-crosslinking wet spinning was screened.The results showed that Ba^(2+) can induce the birefringence of the CA molecular chain,and the Ba^(2+) pre-crosslinking effect is the best when the CA mass fraction is 8.0 wt%.From the perspective of production safety,fiber performance and spinning cost,the coagulation bath of 3.5 wt%BaCl_(2)solution and stretch bath of 1.7 wt%BaCl_(2)solution,that is,combination C with low concentration BaCl_(2)solution,is the best choice.Ba/CAF-8.0/C was obtained under the best conditions.The linear intensity,water absorption and flame retardancy study showed that the breaking strength of Ba/CAF-8.0/C is as high as 1.61 cN/dtex,the water absorption was 649.2%and 574.3%,in deionized water and normal saline,respectively,and the LOI value reached 32.

High-performance magnesium/sodium hybrid ion battery based on sodium vanadate oxide for reversible storage of Na^(+)and Mg^(2+)

Magnesium ion batteries(MIBs)are a potential field for the energy storage of the future but are restricted by insufficient rate capability and rapid capacity degradation.Magnesium-sodium hybrid ion batteries(MSHBs)are an effective way to address these problems.Here,we report a new type of MSHBs that use layered sodium vanadate((Na,Mn)V_(8)O_(20)·5H_(2)O,Mn-NVO)cathodes coupled with an organic 3,4,9,10-perylenetetracarboxylic diimide(PTCDI)anode in Mg^(2+)/Na^(+)hybrid electrolytes.During electrochemical cycling,Mg^(2+)and Na^(+)co-participate in the cathode reactions,and the introduction of Na^(+)promotes the structural stability of the Mn-NVO cathode,as cleared by several ex-situ characterizations.Consequently,the Mn-NVO cathode presents great specific capacity(249.9 mA h g^(−1)at 300 mA g^(−1))and cycling(1500 cycles at 1500 mA g^(−1))in the Mg^(2+)/Na^(+)hybrid electrolytes.Besides,full battery displays long lifespan with 10,000 cycles at 1000 mA g^(−1).The rate performance and cycling stability of MSHBs have been improved by an economical and scalable method,and the mechanism for these improvements is discussed.

磁性聚氨基噻唑吸附剂脱除水体Hg^(2+)性能

聚多巴胺(PDA)辅助负载聚氨基噻唑(PAT)法制备了磁性颗粒吸附剂Fe_(3)O_(4)@SiO_(2)@PDA-PAT。对吸附剂进行了XRD、VSM、TG、SEM、XPS、EDS和Zeta电位等表征分析,考察了吸附剂对Hg^(2+)的吸附性能。结果表明,Fe_(3)O_(4)@SiO_(2)@PDA-PAT具有超顺磁性,在pH小于2时Zeta电位为正,pH大于2时Zeta电位为负。在303 K和Hg^(2+)浓度为50 mg/L模拟废水中,当pH为1.3和5.0时,Hg^(2+)的平衡吸附量分别为121.9 mg/g和153.1 mg/g。在强酸(如pH 1.3)和弱酸(如pH 5.0)环境下Fe_(3)O_(4)@SiO_(2)@PDA-PAT吸附Hg^(2+)的过程均是自发过程,且符合二级动力学模型和Langmuir等温吸附模型。强酸环境下(如pH 1.3)Fe_(3)O_(4)@SiO_(2)@PDA-PAT吸附Hg^(2+)是焓驱动的放热过程,弱酸(如pH 5.0)环境下是熵驱动的吸热过程。用2 mol/L混酸(盐酸和硝酸摩尔比为1∶1)作为解吸液可使Hg^(2+)解吸率达91%以上。在303 K、pH 1.3、Hg^(2+)浓度20 mg/L条件下,当Na^(+)、K^(+)、Mg^(2+)、Ca^(2+)、Cu^(2+)、Zn^(2+)、Ni^(2+)质量浓度为Hg^(2+)的20倍时,Fe_(3)O_(4)@SiO_(2)@PDA-PAT的Hg^(2+)平衡吸附量分别下降了33.2%、32.1%、20.6%、26.7%、21.2%、29.6%、17.8%。在模拟海水下,Hg^(2+)吸附量下降40.9%。Fe_(3)O_(4)@SiO_(2)@PDA-PAT具有较好的Hg^(2+)选择性,具有净化海水脱除重金属的应用潜力。

氮掺杂碳点的制备及其在Hg^(2+)测定中的应用研究

以柠檬酸为碳源,尿素、邻菲罗啉、氨水、硫脲、精氨酸为氮源,通过水热法合成了5种氮掺杂荧光碳点。对合成的碳点进行荧光性能表征,测定了每种碳点的最佳激发和发射波长,在最佳发射波长下,利用荧光猝灭对Hg^(2+)进行检测。结果表明,以精氨酸为氮源制备的碳点对Hg^(2+)检测具有较灵敏的响应,其线性范围为0.25~1.5μmol/L。

lncRNA MIR4435-2HG靶向miR-376a-3p调控胆管癌细胞生物学行为的机制研究

目的 探讨长链非编码RNA(lncRNA)MIR4435-2HG(MIR4435-2HG)对胆管癌细胞增殖、迁移、侵袭、凋亡的影响及其对微小RNA-376a-3p(miR-376a-3p)的调控作用。方法 qRT-PCR法检测人肝内胆管上皮细胞HIBEpic与人胆管癌细胞RBE中MIR4435-2HG、miR-376a-3p的表达。将si-NC、si-MIR4435-2HG、miR-NC、miR-376a-3p mimics、si-MIR4435-2HG联合anti-miR-NC、si-MIR4435-2HG联合anti-miR-376a-3p分别转染至RBE细胞,作为si-NC组、si-MIR4435-2HG组、miR-NC组、miR-376a-3p组、si-MIR4435-2HG+anti-miR-NC组、si-MIR4435-2HG+anti-miR-376a-3p组;采用MTT法、Transwell小室法及流式细胞仪分别检测细胞增殖、迁移、侵袭及凋亡情况;双荧光素酶报告基因实验验证MIR4435-2HG与miR-376a-3p的靶向关系。Western blot检测相关蛋白表达。结果 RBE细胞中MIR4435-2HG表达量升高(P<0.05),miR-376a-3p表达量降低(P<0.05)。与si-NC组比较,si-MIR4435-2HG组MIR4435-2HG表达、细胞活力及CyclinD1、MMP-2、MMP-9蛋白水平降低(P<0.05),迁移及侵袭细胞数减少(P<0.05),细胞凋亡率升高(P<0.05);与miR-NC组比较,miR-376a-3p组细胞活力及CyclinD1、MMP-2、MMP-9蛋白水平降低(P<0.05),迁移及侵袭细胞数减少(P<0.05),miR-376a-3p表达、细胞凋亡率升高(P<0.05)。MIR4435-2HG可靶向调控miR-376a-3p;与si-MIR4435-2HG+anti-miR-NC组比较,si-MIR4435-2HG+anti-miR-376a-3p组细胞活力及CyclinD1、MMP-2、MMP-9蛋白水平升高(P<0.05),迁移及侵袭细胞数增多(P<0.05),miR-376a-3p表达、细胞凋亡率降低(P<0.05)。结论 敲低MIR4435-2HG可通过靶向调控miR-376a-3p进而抑制RBE细胞增殖、迁移、侵袭,并诱导其凋亡。

Mechanochemical synthesis of oxygenated alkynyl carbon materials with excellent Hg(Ⅱ) adsorption performance from CaC2 and carbonates

Adsorptive removal of heavy metal ions from wastewater is very important,and the key is the development of efficient sorbents.In this work,oxygenated alkynyl carbon materials(OACMs)were synthesized via mechanochemical reaction of CaC_(2) and a carbonate(CaCO_(3),Na2CO_(3),or NaHCO_(3))at ambient temperature.The resultant OACMs are micro mesoporous carbon nanomaterials with high specific area(>648 m2 g^(-1)),highly crosslinked texture,and rich alkynyl and oxygenated groups.The OACMs exhibit excellent Hg(Ⅱ)adsorption due to the soft acid-soft base interaction between alkynyl and Hg(Ⅱ),and OACM-3 derived from CaC_(2) and NaHCO_(3) has the saturated Hg(Ⅱ)adsorbance of 483.9 mg g^(-1)along with good selectivity and recyclability.The adsorption is mainly chemisorption following the Langmuir mode.OACM-3 also shows high adsorbance for other heavy metal ions,e.g.256.6 mg g^(-1)for Pb(II),232.4 mg g^(-1)for Zn(II),and 198.7 mg g^(-1)for Cu(II).This work expands the mechnochemical reaction of CaC_(2)with carbonates and possibly other oxyanionic salts,provides a new synthesis approach for functional alkynyl carbon materials with excellent adsorption performance for heavy metal ions,as well as a feasible approach for CO2 resource utilization.

Interfacial built-in electric field and crosslinking pathways enabling WS_(2)/Ti_(3)C_(2)T_(x) heterojunction with robust sodium storage at low temperature

Developing efficient energy storage for sodium-ion batteries(SIBs)by creating high-performance heterojunctions and understanding their interfacial interaction at the atomic/molecular level holds promise but is also challenging.Besides,sluggish reaction kinetics at low temperatures restrict the operation of SIBs in cold climates.Herein,cross-linking nanoarchitectonics of WS_(2)/Ti_(3)C_(2)T_(x) heterojunction,featuring built-in electric field(BIEF),have been developed,employing as a model to reveal the positive effect of heterojunction design and BIEF for modifying the reaction kinetics and electrochemical activity.Particularly,the theoretical analysis manifests the discrepancy in work functions leads to the electronic flow from the electron-rich Ti_(3)C_(2)T_(x) to layered WS_(2),spontaneously forming the BIEF and“ion reservoir”at the heterogeneous interface.Besides,the generation of cross-linking pathways further promotes the transportation of electrons/ions,which guarantees rapid diffusion kinetics and excellent structure coupling.Consequently,superior sodium storage performance is obtained for the WS_(2)/Ti_(3)C_(2)T_(x) heterojunction,with only 0.2%decay per cycle at 5.0 A g^(-1)(25℃)up to 1000 cycles and a high capacity of 293.5 mA h g^(-1)(0.1A g^(-1)after 100 cycles)even at-20℃.Importantly,the spontaneously formed BIEF,accompanied by“ion reservoir”,in heterojunction provides deep understandings of the correlation between structure fabricated and performance obtained.

Solid-state NMR study on sodium intercalation at low voltage window for Na_(3)V_(2)(PO_(4))_(3) as an anode

In-situ XRD,^(31)P NMR and ^(23)Na NMR were used to analyze the interaction behavior of Na_(3)V_(2)(PO_(4))_(3) at low voltage,and then a new intercalation model was proposed.During the transition from Na_(3)V_(2)(PO_(4))_(3) to Na_(4)V_(2)(PO_(4))_(3),Na ions insert into M1,M2 and M3 sites simultaneously.Afterwards,during the transition of Na_(4)V_(2)(PO_(4))_(3)to Na_(5)V_(2)(PO_(4))_(3),Na ions mainly insert into M3 site.

Extending the solid solution range of sodium ferric pyrophosphate:Off‐stoichiometric Na_(3)Fe(2.5)(P_(2)O_(7))_(2)as a novel cathode for sodium‐ion batteries

Iron‐based pyrophosphates are attractive cathodes for sodium‐ion batteries due to their large framework,cost‐effectiveness,and high energy density.However,the understanding of the crystal structure is scarce and only a limited candidates have been reported so far.In this work,we found for the first time that a continuous solid solution,Na_(4−α)Fe_(2+α)_(2)(P_(2)O_(7))_(2)(0≤α≤1,could be obtained by mutual substitution of cations at center‐symmetric Na3 and Na4 sites while keeping the crystal building blocks of anionic P_(2)O_(7) unchanged.In particular,a novel off‐stoichiometric Na_(3)Fe(2.5)(P_(2)O_(7))_(2)is thus proposed,and its structure,energy storage mechanism,and electrochemical performance are extensively investigated to unveil the structure–function relationship.The as‐prepared off‐stoichiometric electrode delivers appealing performance with a reversible discharge capacity of 83 mAh g^(−1),a working voltage of 2.9 V(vs.Na^(+)/Na),the retention of 89.2%of the initial capacity after 500 cycles,and enhanced rate capability of 51 mAh g^(−1)at a current density of 1600 mA g^(−1).This research shows that sodium ferric pyrophosphate could form extended solid solution composition and promising phase is concealed in the range of Na_(4−α)Fe_(2+α)_(2)(P_(2)O_(7))_(2),offering more chances for exploration of new cathode materials for the construction of high‐performance SIBs.

聚丙烯腈改性及其对Hg^(2+)吸附研究

Hg^(2+)是生态环境中存在的对人体健康危害最大的重金属离子之一。吸附法是一种去除Hg^(2+)最简单高效的方法。因此设计成本低廉、吸附性能好且能循环利用的吸附剂是非常重要的。采用乳液自由基聚合技术制备聚丙烯腈,然后用三乙烯四胺对聚丙烯腈进行改性,得到改性后的聚丙烯腈。以废水中Hg^(2+)为吸附对象,考察不同的实验条件下,改性后的聚丙烯腈对Hg^(2+)的吸附性能。在pH值为6,Hg^(2+)浓度为40 mg/L,即时吸附量q_(t)达到最大;吸附30 min后吸附基本达到饱和。分别用伪一级吸附和伪二级吸附方程动力学模型对实验数据进行拟合,结果表明,用伪二级动力学方程可以更好描述吸附过程,说明三乙烯四胺改性聚丙烯腈对Hg^(2+)的吸附过程受Hg^(2+)扩散和-NH_(2)与Hg^(2+)的配位反应影响,为化学吸附。

Determination of Ten Kinds of Alpha-2 Agonists Residues in Animal Derived Food by UHPLC-Triple Quadrupole/Composite Linear Ion Trap Mass Spectrometry

[Objectives]The paper was to establish an ultra high performance liquid chromatography-quadrupole/linear ion trap complex mass spectrometry for the determination of 10 kinds ofα2-receptor agonists in animal derived food.[Methods]The samples were extracted with sodium carbonate buffer solution and ethyl acetate,and analyzed by mass spectrometry after solid phase extraction and high performance liquid chromatography separation.[Results]Ten kinds ofα2-receptor agonists showed a good linear relationship in the range of 1-100μg/mL,with the average recovery of over 69%and the relative standard deviation less than 8.32%.The detection limit of 10 kinds of α_(2)-receptor agonists was up to 1μg/kg.[Conclusions]The method has good selectivity and strong anti-interference ability,and can meet the requirements of 10 kinds ofα2-receptor agonists residues in animal derived food.