PREPARATION OF BAGASSE XANTHATES （BX） AND NICKEL REMOVAL FROM WASTEWATER BY BX

ＰＲＥＰＡＲＡＴＩＯＮＯＦＢＡＧＡＳＳＥＸＡＮＴＨＡＴＥＳ（ＢＸ）ＡＮＤＮＩＣＫＥＬＲＥＭＯＶＡＬＦＲＯＭＷＡＳＴＥＷＡＴＥＲＢＹＢＸＺｈｏｎｇＣｈａｎｇｇｅｎｇ；ＴａｎｇＤｏｎｇｇｏｎｇ；ＣｈｅｎＱｉａｏｙｕｎ（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍｉｓ...     

螺桨烷型分子BX[(CH_2)_n]_3和BX(CH_2)[CH(CH_2)_nCH](X=N,P)的结构和性质

采用密度泛函理论(DFT)研究了螺桨烷型分子BX[(CH2)n]3和BX(CH2)[CH(CH2)n CH](X=N,P;n=1-6)的结构、稳定性、化学键和电子光谱性质.计算结果表明这些分子都是稳定的.BX[(CH2)n]3(X=N,P;n=1-6)的最高占据分子轨道(HOMO)和最低空分子轨道(LUMO)之间的能隙均大于5.20 eV,其中BN[CH2]3和BP[CH2]3的能隙超过7.0 eV,与C5H6的能隙(7.27 eV)很接近,BX(CH2)[CH(CH2)n CH](X=N,P;n=1-6)的能隙在6.80 eV左右.所研究分子能量的二阶差分表明BN[(CH2)3]3、BP[(CH2)4]3及BX(CH2)[CH(CH2)2CH](X=N,P)是最稳定的.BX[(CH2)n]3的Wiberg键级表明除了BN[(CH2)n]3(n=2和6)中不存在B―N键,其它化合物中B和N均形成了化学键,BP[(CH2)n]3中除了BP[(CH2)2]3不存在B―P键,其它的均存在.电子密度的拓扑分析表明N―B键属于离子键,而P―B键具有共价键特征.BX[(CH2)n]3(X=N,P)的第一垂直激发能分别在191.1-284.8 nm和191.8-270.1 nm之间,BX(CH2)[CH(CH2)n CH](X=N,P)的第一垂直激发能分别在190.5-199.7 nm和209.0-221.3 nm之间.     

Vibrational spectra of tropylium tetrahaloborates [C7H7] [BX4] (X  Br or I)

Raman and i.r. studies of the title compounds, which are salts of the planar D_7h tropylium cation, provide complete sets of vibrational frequencies for the tetrahaloborate anions, including Raman data for [BI₄]⁻ for which ν₁(a₁) = 169, ν₂(e) = 83, ν₃(t₂) = 515 (¹¹B), 543 (¹⁰B) and ν₄(t₂) = 117 cm⁻¹.     

Nickel(II) hydride and fluoride pincer complexes and their reactivity with Lewis acids BX3·L (X = H, L = thf; X = F, L = Et2O)

Reaction of the pincer hydride complex ((tBu)PCP)Ni(H) [(tBu)PCP = 2,6-C(6)H(3)(CH(2)P(t)Bu(2))(2)] with BH(3)·thf in THF at 190 K generates the corresponding borohydride complex ((tBu)PCP)Ni(BH(4)). The kinetically stable (but thermodynamically unstable) species undergoes reversible borane loss. The related fluoride complex ((tBu)PCP)Ni(F) shows the same reactivity towards BF(3)·Et(2)O, producing ((tBu)PCP)Ni(BF(4)) as the main final product. The processes were followed through multinuclear NMR spectroscopy and DFT calculations, at the M06//6-31+G(d,p) level of theory.     

Design of new organic superacids with fused and isolated pyrrole and cyclopentadiene rings and assessment of effect of –BX2 (X = H,F, Cl,CN) substituents on the acidity enhancement: A DFT analysis

New classes of organic Brønsted acids were designed with pyrrole and cyclopentadiene scaffolds, and their acidity was assessed theoretically by the B3LYP/6-311++G(d,p) method. The hydrogen atom of NH group in pyrrole was substituted by an –BX₂ (X = H, F, Cl, CN, CF₃). The boron atom stabilizes the conjugated bases by interaction with the center of negative charge after deprotonation. The acidity of the compounds was promoted by substitution of the hydrogen atoms of the rings with CN moiety as a strong electron withdrawing group. Also, after deprotonation, delocalization of the negative charge in both pyrrole and cyclopentadiene rings causes stability of the conjugated bases and consequently enhances the acidity. The charge delocalization in the neutral acids and their conjugated bases was compared using nucleus-independent chemical shift index. Enthalpies and Gibbs free energies of deprotonation in gas phase, ∆H_acid and ∆G_acid, were used as a measure of acidity. Both compounds with isolated and fused pyrrole and cyclopentadiene rings were investigated and it was found that the formers are more acidic. Using these strategies, several acids and superacids with wide range of acidity with ∆G_acid values of 244 to 328 kcal mol⁻¹ were obtained.     

等浓度的氯化铵和硫酸铵溶液哪个pH高

有中学化学参考资料题:0.10 mol/L的NH4Cl和(NH4)2SO4溶液哪个pH值高?这似乎是个中学生可做的简单题目,仔细考虑不是如此.如果简单地认为盐酸和硫酸都是强酸,而硫酸是二元酸,硫酸铵溶液中铵盐浓度为0.20 mol/L,那么NH4Cl溶液pH高,那是不妥的.硫酸是二元酸,第一个氢离子能完全电离,第二个氢离子部分电离,如此考虑情况怎么样呢?是不是答案发生变化?这要通过计算来说明.     

Enhanced efficiency and stability in Sn-based perovskite solar cells with secondary crystallization growth

The conversion efficiencies reported for Tin(Sn)halide-based perovskite solar cells(PSCs)fall a large gap behind those of lead halide-based PSCs,mainly because of poor film quality of the former.Here we report an efficient strategy based on a simple secondary crystallization growth(SCG)technique to improve film quality for tin halide-based PSCs by applying a series of functional amine chlorides on the perovskite surface.They were discovered to enhance the film crystallinity and suppress the oxidation of Sn²⁺remarkably,hence reduce trap state density and non-irradiative recombination in the absorber films.Furthermore,the SCG film holds the band levels matching better with carrier transport layers and herein favoring charge extraction at the device interfaces.Consequently,a champion device efficiency of 8.07% was achieved alo ng with significant enhancements in VOC and JSC,in contrast to 5.35% of the control device value.Moreover,the SCG film-based devices also exhibit superior stability comparing with the control one.This work explicitly paves a novel and general strategy for developing high performance lead-free PSCs.     

Energy level engineering of charge selective contact and halide perovskite by modulating band offset:Mechanistic insights

Mixed cation and anion based perovskites solar cells exhibited enhanced stability under outdoor conditions,however,it yielded limited power conversion efficiency when TiO₂ and Spiro-OMeTAD were employed as electron and hole transport layer(ETL/HTL)respectively.The inevitable interfacial recombination of charge carriers at ETL/perovskite and perovskite/HTL interface diminished the efficiency in planar(n-i-p)perovskite solar cells.By employing computational approach for uni-dimensional device simulator,the effect of band offset on charge recombination at both interfaces was investigated.We noted that it acquired cliff structure when the conduction band minimum of the ETL was lower than that of the perovskite,and thus maximized interfacial recombination.However,if the conduction band minimum of ETL is higher than perovskite,a spike structure is formed,which improve the performance of solar cell.An optimum value of conduction band offset allows to reach performance of 25.21%,with an open circuit voltage(VOC)of 1231 mV,a current density JSC of 24.57 mA/cm² and a fill factor of 83.28%.Additionally,we found that beyond the optimum offset value,large spike structure could decrease the performance.With an optimized energy level of Spiro-OMeTAD and the thickness of mixed-perovskite layer performance of 26.56% can be attained.Our results demonstrate a detailed understanding about the energy level tuning between the charge selective layers and perovskite and how the improvement in PV performance can be achieved by adjusting the energy level offset.     

A new strategy to access Co/N co-doped carbon nanotubes as oxygen reduction reaction catalysts

Carbon nanotubes(CNTs),as one-dimensional nanomaterials,show great potential in energy conversion and storage due to their efficient electrical conductivity and mass transfer.However,the security risks,time-consuming and high cost of the preparation process hinder its further application.Here,we develop that a negative pressure rather than a following gas environment can promote the generation of cobalt and nitrogen co-doped CNTs(Co/N-CNTs) by using cobalt zeolitic imidazolate framework(ZIF-67) as a precursor,in which the negative pressure plays a key role in adjusting the size of cobalt nanoparticles and stimulating the rearragement of carbon atoms for forming CNTs.Importantly,the obtained Co/N-CNTs,with high content of pyridinic nitrogen and abundant graphitized structure,exhibit superior catalytic activity for oxygen reduction reaction(ORR) with half-wave potential(E_1/2) of 0.85 V and durability in terms of the minimum current loss(2%) after the 30,000 s test.Our development provides a new pathway for large-scale and cost-effective preparation of metal-doped CNTs for various applications.     

Recent Advances of Pure Organic Room Temperature Phosphorescence Materials for Bioimaging Applications

Bioimaging,as a powerful and helpful tool,which allows people to investigate deeply within living organisms,has contributed a lot for both clinical theranostics and scientific research.Pure organic room temperature phosphorescence(RTP)materials with the unique features of ultralong luminescence lifetime and large Stokes shift,can efficiently avoid biological autofluorescence and scattered light through a time-resolved imaging modality,and thus are attracting increasing attention.This review classifies pure organic RTP materials into three categories,including small molecule RTP materials,polymer RTP materials and supramolecular RTP materials,and summarizes the recent advances of pure organic RTP materials for bioimaging applications.     

Stabilizing High-voltage Cathode Materials for Next-generation Li-ion Batteries

The pressing demand for high-energy/power lithium-ion batteries requires the deployment of cathode materials with higher capacity and output voltage.Despite more than ten years of research,high-voltage cathode mate-rials,such as high-voltage layered oxides,spinel LiNi0.5Mn1.5O4,and high-voltage polyanionic compounds still cannot be commercially viable due to the instabilities of standard electrolytes,cathode materials,and cathode electrolyte interphases under high-voltage operation.This paper summarizes the recent advances in addressing the surface and interface issues haunting the application of high-voltage cathode materials.The understanding of the limitations and advantages of different modification protocols will direct the future endeavours on advancing high-energy/power lithium-ion batteries.     

Conformational Properties of Comb-shaped Polyelectrolytes with Negatively Charged Backbone and Neutral Side Chains Studied by a Generic Coarse-grained Bead-and-Spring Model

A generic coarse-grained bead-and-spring model,mapped onto comb-shaped polycarboxylate-based(PCE)superplasticizers,is developed and studied by Langevin molecular dynamics simulations with implicit solvent and explicit counterions.The agreement on the radius of gyration of the PCEs with experiments shows that our model can be useful in studying the equilibrium sizes of PCEs in solution.The effects of ionic strength,side-chain number,and side-chain length on the conformational behavior of PCEs in solution are explored.Single-chain equilibrium properties,including the radius of gyration,end-to-end distance and persistenee length of the polymer backbone,shape-asphericity parameter,and the mean span dimension,are determined.It is found that with the increase of ionic strength,the equilibrium sizes of the polymers decrease only slightly,and a linear dependenew of the persistence length of backbone on the Debye screening length is found,in good agreement with the theory developed by Dobrynin.Increasing side-chain numbers and/or side-chain lengths increases not only the equilibrium sizes(radius of gyration and mean span)of the polymer as a whole,but also the persistence length of the backbone due to excluded volume interactions.     

Suppressing trap states and energy loss by optimizing vertical phase distribution through ternary strategy in organic solar cells

Suppressing the trap-state density and the energy loss via ternary strategy was demonstrated.Favorable vertical phase distribution with donors(acceptors)accumulated(depleted)at the interface of active layer and charge extraction layer can be obtained by introducing appropriate amount of polymer acceptor N2200 into the systems of PBDB-T:IT-M and PBDB-TF:Y6.In addition,N2200 is gradiently distributed in the vertical direction in the ternary blend film.Various measurements were carried out to study the effects of N2200 on the binary systems.It was found that the optimized morphology especially in vertical direction can significantly decrease the trap state density of the binary blend films,which is beneficial for the charge transport and collection.All these features enable an obvious decrease in charge recombination in both PBDB-T:IT-M and PBDB-TF:Y6 based organic solar cells(OSCs),and power conversion efficiencies(PCEs)of 12.5%and 16.42%were obtained for the ternary OSCs,respectively.This work indicates that it is an effective method to suppress the trap state density and thus improve the device performance through ternary strategy.     

Three-dimensionalization via control of laser-structuring parameters for high energy and high power lithium-ion battery under various operating conditions

Laser-structuring is an effective method to promote ion diffusion and improve the performance of lithium-ion battery(LIB)electrodes.In this work,the effects of laser structuring parameters(groove pitch and depth)on the fundamental characteristics of LIB electrode,such as interfacial area,internal resistances,material loss and electrochemical performance,are investigated,LiNi_0.5Co_0.2Mn_0.3O₂ cathodes were structured by a femtosecond laser by varying groove depth and pitch,which resulted in a material loss of 5%-14%and an increase of 140%-260%in the in terfacial area between electrode surface and electrolyte.It is shown that the importance of groove depth and pitch on the electrochemical performance(specific capacity and areal discharge capacity)of laser-structured electrode varies with current rates.Groove pitch is more im porta nt at low current rate but groove depth is at high curre nt rate.From the mapping of lithium concentration within the electrodes of varying groove depth and pitch by laser-induced breakdown spectroscopy,it is verified that the groove functions as a diffusion path for lithium ions.The ionic,electronic,and charge transfer resistances measured with symmetric and half cells showed that these internal resistances are differently affected by laser structuring parameters and the changes in porosity,ionic diffusion and electronic pathways.It is demonstrated that the laser structuring parameters for maximum electrode performance and minimum capacity loss should be determined in consideration of the main operating conditions of LIBs.     

Mesh-like vertical structures enable both high areal capacity and excellent rate capability

In order to balance electrochemical kinetics with loading level for achieving efficient energy storage with high areal capacity and good rate capability simultaneously for wearable electronics,herein,2 D meshlike vertical structures(NiCo_2 S_4@Ni(OH)_2) with a high mass loading of 2.17 mg cm^-2 and combined merits of both 1 D nanowires and 2 D nanosheets are designed for fabricating flexible hybrid supercapacitors.Particularly,the seamlessly interconnected NiCo_2 S_4 core not only provides high capacity of 287.5 μAh cm^-2 but also functions as conductive skeleton for fast electron transport;Ni(OH)_2 sheath occupying the voids in NiCo_2 S_4 meshes contributes extra capacity of 248.4 μAh cm^-2;the holey features guarantee rapid ion diffusion along and across NiCO_2 S_4@Ni(OH)_2 meshes.The resultant flexible electrode exhibits a high areal capacity of 535.9 μAh cm^-2(246.9 mAh g^-1) at 3 mA cm^-2 and outstanding rate performance with 84.7% retention at 30 mA cm^-2,suggesting efficient utilization of both NiCo_2 S_4 and Ni(OH)_2 with specific capacities approaching to their theoretical values.The flexible solid-state hybrid device based on NiCo_2 S_4@Ni(OH)_2 cathode and Fe_2 O_3 anode delivers a high energy density of 315 μWh cm^-2 at the power density of 2.14 mW cm^-2 with excellent electrochemical cycling stability.     

Core-shell lipid-polymer nanoparticles as a promising ocular drug delivery system to treat glaucoma

Nowadays,tremendous researches have been focused on the core-shell lipid-polymer nanoparticles(LPNs) due to the advantages of both liposomes and polymer nanoparticles.In this work,LPNs were applied to encapsulate brinzolamide(Brz-LPNs) for achieving sustained drug release,improving drug corneal permeation and enhancing drug topical therapeutic effect.The structure of Brz-LPNs was composed of poly(lactic-co-glycolic) acid(PLGA) nanocore which encapsulated Brz(Brz-NPs) and lipid shell around the core.Brz-LPNs were prepared by a modified thin-film dispersion method.With the parameters optimization of Brz-LPNs,optimal Brz-LPNs showed an average particle size of151.23±1.64 nm with a high encapsulation efficiency(EE) of 86.7%±2.28%.The core-shell structure of Brz-LPNs were confirmed by transmission electronic microscopy(TEM).Fourier transformed infrared spectra(FTIR) analysis proved that Brz was successfully entrapped into Brz-LPNs.Brz-LPNs exhibited obvious sustained release of Brz,compared with AZOPT^■ and Brz-LPs.Furthermore,the corneal accumulative permeability of Brz-LPNs significantly increased compared to the commercial available formulation(AZOPT^■) in vitro.Moreover,Brz-LPNs(1 mg/mL Brz) showed a more sustained and effective intraocular pressure(IOP) reduction than Brz-LPs(1 mg/mL) and AZOPT^■(10 mg/mL Brz) in vivo.In conclusion,Brz-LPNs,as promising ocular drug delivery systems,are well worth developing in the future for glaucoma treatment.     

Improved interfacial property by small molecule ethanediamine for high performance inverted planar perovskite solar cells

We report a simple and effective method to realize desirable interfacial property for inverted planar perovskite solar cells(PSCs)by using small molecule ethanediamine for the construction of a novel polyelectrolyte hole transport material(P3CT-ED HTM).It is found that P3CT-ED can not only improve the hole transport property of P3CT-K but also improve the crystallinity of adjacent perovskite film.In addition,the introduction of ethanediamine into P3CT realigns the conduction and valence bands upwards,passivates surface defects and reduces nonradiative recombination.As a consequence,compared to P3CT-K hole transport layer(HTL)based devices,the average power conversion efficiency(PCE)is boosted from17.2% to 19.6% for the counterparts with P3CT-ED,with simultaneous enhancement in open circuit voltage and fill factor.The resultant device displays a champion PCE of 20.5% with negligible hysteresis.     

茶叶浸出液中农药残留表面拉曼光谱检测与初步定量分析

选取甲基对硫磷和水胺硫磷为研究对象,改良了传统的QuEChERS前处理工艺,以自制纳米金溶胶为增强基底,利用表面增强拉曼光谱(SERS)技术,对茶叶浸出液中的农药残留进行检测。通过比对两种有机磷农药的拉曼特征峰进行定性分析。同时,选取570,1034,1107和1202 cm^-1等拉曼位移附近的特征峰光谱数据,利用微分等数学手段,结合偏最小二乘法(PLSR)建立回归方程,预测样品中农药残留含量。所得预测数值与气相色谱-质谱联用(GC-MS)法检测值对比,验证本方法的可行性与可信度。结果表明:基于SERS技术对上述两种有机磷农药的检出限可达0.05 mg/L;通过数学模型分析建立回归方程,其线性相关系数范围为0.9077~0.9824,预测均方根误差(RMSEP)范围为0.77%~2.68%;利用回归方程得到的预测值与GC-MS检测结果基本接近,相对误差范围-5.16%~9.03%,回收率为81.4%~115.1%,说明可以用SERS技术对茶叶浸出液中的有机磷农药残留进行定性和初步定量分析。     

Constructing an unbalanced structure toward high working voltage for improving energy density of non-aqueous carbon-based electrochemical capacitors

The energy density of non-aqueous carbon-based electrochemical capacitors(cEC)is mainly determined by the specific capacitance and operational voltage range.In this study,we propose to construct an unbalanced structure to make full use of stable voltage range for improving energy density.The stable voltage range is firstly carefully explored using cyclic voltammetry.Then an unbalanced carbon-based electrochemical capacitor(ucEC)is constructed with an optimized positive electrode to negative electrode weight ratio and voltage range.Its electrochemical performance is comprehensively investigated,including energy density,power density as well as cycle life.The ucEC is capable to deliver an improved energy density up to 64.9 Wh/kg(1.4 times as high as a general cEC)without sacrificing the power density and cycle life.The electrode properties after cycling are also analyzed,illustrating the change of electrode potential caused by unbalanced structure.The proposed structure demonstrates a great potential for improving the energy density at little cost of electrode design and cell configuration.     

Fully automated sample treatment method for high throughput proteome analysis

The bottom-up strategy for proteome analysis typically employs a multistep sample preparation workflow that suffers from being time-consuming and sample loss or contamination caused by the off-line manual operation.Herein,we developed a hollow fibre membrane(HFM)-aided fully automated sample treatment(FAST)method.Due to the confinement effects of HFMs and the immobilized enzymatic reactor,the proteome samples could be denatured,reduced,desalted and digested within 8–20 min via the one-stop service.This method also showed superiority in trace sample analysis.In one and half hours,we could identify about 1,600 protein groups for 500 HeLa cells as the starting materials,1.5–8 times more than those obtained by previously reported methods.Through the on-line combination of FAST with nano-liquid chromatography-electrospray ionization tandem mass spectrometry(nanoLC-ESI-MS/MS),we further established a fully integrated platform for label-free quantification of proteome with high reproducibility and precision.Collectively,FAST presented here represents a major advance in the high throughput sample treatment and quantitative analysis of proteomes.