Solid-liquid phase equilibrium for the system ammonium polyphosphate-urea ammonium nitrate-potassium chloride-water at 273.2 K

Based on the dynamic method,a quaternary system of ammonium polyphosphate (APP)-urea ammonium nitrate (UAN,CO(NH_(2))_(2)-NH_(4)NO_(3))-potassium chloride (KCl)-H_(2)O and its subsystems (APP-[CO(NH_(2))_(2)-NH_(4)NO_(3)]-H_(2)O,KCl-[CO(NH_(2))_(2)-NH_(4)NO_(3)]-H_(2)O and APP-KCl-H_(2)O) were systematically investigated at the temperature of 273.2 K.Each ternary phase diagram contains one invariant point and three crystallization regions.The crystallization regions are:(1)(NH_(4))_(3)HP_(2)O_(7),(NH_(4))_(4)P_(2)O_(7)and ((NH_(4))_(3)HP_(2)O_(7)+(NH_(4))_(4)P_(2)O_(7)) for APP-[CO(NH_(2))_(2)-NH_(4)NO_(3)]-H_(2)O diagram;(2) KCl,KNO_(3)and(KCl+KNO_(3)) for KCl-[CO(NH_(2))_(2)-NH_(4)NO_(3)]-H_(2)O diagram and (3)(NH_(4))_(3)HP_(2)O_(7),KCl and((NH_(4))_(3)HP_(2)O_(7)+KCl) for APP-KCl-H_(2)O diagram.The quaternary phase diagram of APP-[CO(NH_(2))_(2)-NH_(4)NO_(3)]-KCl-H_(2)O has no quaternary invariant point but includes four solid phase crystallization regions,i.e.,(NH_(4))_(3)HP_(2)O_(7),(NH_(4))_(4)P_(2)O_(7),KNO_(3)and KCl,in which the KNO_(3)region occupies the largest area.The maximum total nutrient content (N+P_(2)O_(5)+K_(2)O) existing as ionic forms in the APP-[CO(NH_(2))_(2)-NH_(4)NO_(3)]-H_(2)O,KCl-[CO(NH_(2))_(2)-NH_(4)NO_(3)]-H_(2)O,APP-KCl-H_(2)O and quaternary systems is 44.70%,32.86%,45.56%and 46.23%(mass),respectively,indicating that the maximum nutrient content can be reached using raw materials of the corresponding systems to prepare liquid fertilizer.In the quaternary system,the content of NH_(4)~+-N ascends with the increase of the total nutrient content,while the contents of NO_(3)^(-)-N and CO(NH_(2))_(2)-N increase with elevated total N.This work can help optimize the operating parameters for the production,storage and transportation of liquid fertilizers.

Mechanism and kinetics study on removal of Iron from phosphoric acid by cation exchange resin

Iron element is one of the main impurities in wet-process phosphoric acid and it has a significant impact on the subsequent phosphorus chemical products. This paper studied the feasibility of using Sinco-430 cation exchange resin for iron removal from phosphoric acid. The specific surface area and the total exchange capacity of resin were 8.91 m2·g-1 and 5.18 mmol·g-1, respectively. The sorption mechanism was determined by FTIR and XPS and the results indicated that iron was combined with-SO3 H in resin. The removal process was studied as a function of temperature, H3 PO4 content and mass ratio between resin and solution. The unit mass of resin to remove iron was 0.058 g·g-1 resin when the operating parameters were T = 50 ℃, H3 PO4 content = 27.61 wt%and S/L = 0.1, respectively. Kinetics study demonstrated that pseudo-second-order reaction model fits this study best and the calculated activation energy of overall reaction is 29.10 kJ·mol-1. The overall reaction process was mainly controlled by pore diffusion.

A fast and accurate initial alignment method for strapdown inertial navigation system on stationary base

In this work,a fast and accurate stationary alignment method for strapdown inertial navigation system （SINS） is proposed. It has been demonstrated that the stationary alignment of SINS can be improved by employing the multiposition technique,but the alignment time of the azimuth error is relatively longer. Over here, the two-position alignment principle is presented. On the basis of this SINS error model, a fast estimation algorithm of the azimuth error for the initial alignment of SINS on stationary base is derived fully from the horizontal velocity outputs and the output rates, and the novel azimuth error estimation algorithm is used for the two-position alignment. Consequently, the speed and accuracy of the SINS＇ s initial alignment is enhanced greatly. The computer simulation results illustrate the efficiency of this alignment method.

The development road of ammonium phosphate fertilizer in China

Ammonium phosphate fertilizer is the compounds containing nitrogen and phosphorus that are usually produced through the neutralization reaction of phosphoric acid and ammonia.At present,there are a variety of products,such as slurry monoammonium phosphate(MAP),diammonium phosphate(DAP),industrial grade MAP,water soluble MAP,water soluble ammonium polyphosphate(APP)and so on.After more than 60 years of development,China’s ammonium phosphate fertilizer industry has experienced the road of from scratch and from weak to strong.The successful development of the slurry MAP technology ended the history that the high concentration phosphate fertilizer cannot be produced by using the medium and low grade phosphate ore.The continuous,stable and large-scale production of DAP plant provides sufficient guarantee for DAP products in China.The development of new ammonium phosphate fertilizer products,such as industrial grade MAP,water soluble MAP,water soluble APP,provides technical support for the transformation and upgrading of phosphorus chemical enterprises.In this paper,the production methods,the development history and the latest research progress of ammonium phosphate fertilizers were reviewed.

In situ construction of Co/N/C-based heterojunction on biomass-derived hierarchical porous carbon with stable active sites using a Co-N protective strategy for high-efficiency ORR,OER and HER trifunctional electrocatalysts

The facile designs and fabrication of noble metal-free electrocatalysts are highly required to achieve multifunctional catalytic activity with excellent stability in Zn-air batteries,fuel cells and water splitting systems.Herein,a heterostructure engineering is applied to construct the high performance Co,Ncontaining carbon-based multifunctional electrocatalysts with the feature of isotype(i.e.n-n type Co_(2)N_(0.67)-BHPC)and anisotype(i.e.p-n type Co_(2)O_(3)-BHPC)heterojunctions for ORR,OER and HER.The nn type Co_(2)N_(0.67)-BHPC,in which biomass(e.g.mushroom)-derived hierarchical porous carbon(BHPC)incorporated with nonstoichiometric active species Co_(2)N_(0.67),is fabricated by using an in situ protective strategy of macrocyclic central Co-N_(4) from CoTPP(5,10,15,20-tetrakis(phenyl)porphyrinato cobalt)precursor through the intermolecularπ-πinteractions between CoTPP and its metal-free analogue H_(2) TPP.Meanwhile,an unprotected strategy of macrocyclic central Co-N_(4) from CoTPP can afford the anisotype Co_(2)O_(3)-BHPC p-n heterojunction.The as-prepared n-n type Co_(2)N_(0.67)-BHPC heterojunction exhibited a higher density of Co-based active sites with outstanding stability and more efficient charge transfer at the isotype heterojunction interface in comparison with p-n type Co_(2)O_(3)-BHPC heterojunction.Consequently,for ORR,Co_(2)N_(0.67)-BHPC exhibits the more positive onset and half-wave potentials of 0.93 and 0.86 V vs.RHE,respectively,superior to those of the commercial 20 wt%Pt/C and most of Cobased catalysts reported so far.To drive a current density of 10 mA cm^(-2),Co_(2)N_(0.67)-BHPC also shows the lower overpotentials of 0.34 and 0.21 V vs.RHE for OER and HER,respectively.Furthermore,the Zn-air battery equipped with Co_(2)N_(0.67)-BHPC displays higher maximum power density(109 mW cm^(-2))and charge-discharge cycle stability.Interestingly,the anisotype heterojunction Co_(2)O_(3)-BHPC as trifunctional electrocatalyst reveals evidently photoelectrochemical enhancement compared with the photostable Co_(2)N_(0.67)-BHPC.That is to say,isotype heterojunction material(n-n type Co^(2)N_(0.67)-BHPC)is equipped with better electrocatalytic performance than anisotype one(p-n type Co_(2)O_(3)-BHPC),but the opposite is true in photoelectrochemical catalysis.Meanwhile,the possible mechanism is proposed based on the energy band structures of the Co_(2)N_(0.67)-BHPC and Co_(2)O_(3)-BHPC and the cocatalyst effects.The present work provides much more possibilities to tune the electrocatalytic and photoelectrochemical properties of catalysts through a facile combination of heterostructure engineering protocol and macrocyclic central metal protective strategy.

On solitary waves.Part 2 A unified perturbation theory for higher-order waves

A unified perturbation theory is developed here for calculating solitary waves of all heights by series expansion of base flow variables in powers of a small base parameter to eighteenth order for the one-parameter family of solutions in exact form, with all the coefficients determined in rational numbers. Comparative studies are pursued to investigate the effects due to changes of base parameters on （i） the accuracy of the theoretically predicted wave properties and （ii） the rate of convergence of perturbation expansion. Two important results are found by comparisons between the theoretical predictions based on a set of parameters separately adopted for expansion in turn. First, the accuracy and the convergence of the perturbation expansions, appraised versus the exact solution provided by an earlier paper [1] as the standard reference, are found to depend, quite sensitively, on changes in base parameter. The resulting variations in the solution are physically displayed in various wave properties with differences found dependent on which property （e.g. the wave amplitude, speed, its profile, excess mass, momentum, and energy）, on what range in value of the base, and on the rank of the order n in the expansion being addressed. Secondly, regarding convergence, the present perturbation series is found definitely asymptotic in nature, with the relative error δ （n） （the relative mean-square difference between successive orders n of wave elevations） reaching a minimum, δm at a specific order, n = n both depending on the base adopted, e.g. nm,α= 11-12 based on parameter α （wave amplitude）, nm,δ = 15 on δ （amplitude-speed square ratio）, and nm.ε= 17 on ε （ wave number squared）. The asymptotic range is brought to completion by the highest order of n = 18 reached in this work.

Leaching calcium from phosphogypsum desulfurization slag by using ammonium chloride solution: Thermodynamics and kinetics study

Phosphogypsum(PG) desulfurization slag is a calcium-rich residue from reductive decomposition of PG using sulfur as the reductant. We proposed a technology of preparation light calcium carbonate with PG desulfurization slag, which mainly contains two steps: leaching and carbonizing. In this work, we concentrated on the former, in which ammonium chloride aqueous solution was utilized as leaching agent to extract calcium from the slag, and conducted thermodynamics and kinetics study on it. Fact Sage software was employed to do thermodynamic and phase equilibrium diagram calculations. The influence of leaching conditions including agitation speed, initial concentration of leaching solution, reaction temperature, and liquid/solid ratio on the calcium leaching rate was discussed in detail by means of experiment optimal design. A kinetic model developed from the shrinking core model was given to describe the leaching process. The apparent kinetic activation energy(Ea) of the leaching reaction was calculated to be 10.58 kJ·mol^-1.

Solubility and solution thermodynamics of ammonium dihydrogen phosphate in the water–methanol system

The solubility of ammonium dihydrogen phosphate(MAP)in the water–methanol system is essential for antisolvent crystallization studies.To investigate the effect of methanol on the solubility of MAP in water,the solubility of MAP in the water–methanol system was determined by dynamic method and static equilibrium method at temperatures ranging from 293.2 to 343.2 K at atmospheric pressure.Results showed that the solubility of MAP increased with the increase of temperature and the increase of water mole fraction in the water–methanol system.The experimental solubility data were correlated with the modified Apelblat equation,the combined nearly ideal binary solvent/Redlich–Kister(CNIBS/R–K)model and the Jouyban–Acree model.The calculated results based on these three models were in very good agreement with the experimental data with the average relative deviations of 0.65%,0.97%,and 5.38%,respectively.Simultaneously,the thermodynamic properties of the MAP dissolution process in the water–methanol system,including Gibbs energy change,enthalpy,and entropy were obtained by the Van’t Hoff equation,which can be used to assess the crystallization process.

Optical and electrochemical dual detection ofβ-lactoglobulin based on the methylene blue@copper-based metal-organic framework

β-lactoglobulin is an effective indicator of allergic protein detection.Herein,we produced a copper-based metal-organic framework coated with methylene blue,to realize the optical and electrochemical dual detection ofβ-lactoglobulin.Methylene blue was successfully encapsulated inside the copper-based metal-organic framework and released after addition ofβ-lactoglobulin.As the concentration ofβ-lactoglobulin increased,the intensity of the ultraviolet absorption band and the response current increased with the increasing concentration of methylene blue released from the copper-based metal-organic framework.The optical detection range is from 0.10 mg/mL to 10 mg/mL,and the detection limit is 0.10 mg/mL.The electrochemical detection range is from 1.0×10^(-7) mg/mL to 8.0×10^(-7) mg/mL,the detection limit is 2.0×10^(-8) mg/mL.The dual detection strategy,with no interfere with each other,played a synergetic role in the quick qualitative and precise quantitative analyses ofβ-lactoglobulin in a wide range of applications.

The Current State and Progress of Mpox Vaccine Research

On July 23,2022,the World Health Organization(WHO)declared the monkeypox(mpox)outbreak a“Public Health Emergency of International Concern.”Since 2022,outbreaks of mpox in many countries around the world have primarily resulted in fatalities among immunocompromised individuals,such as untreated HIV/AIDS patients.Since the eradication of smallpox was declared by the WHO in 1980,the global vaccination against smallpox has been gradually discontinued.China also stopped routine smallpox vaccination in 1981.The protective effect of the smallpox vaccine has decreased over time due to aging and declining immunity in those who were vaccinated.For individuals,timely vaccination against smallpox is an effective means of protection against mpox.However,due to safety concerns with the smallpox vaccine and the limitations of current mpox vaccines,there is no vaccine that is safe,effective,and has low side effects applied in clinical settings.This article provides a comprehensive review of the development of mpox virus(MPXV)vaccines,their application in special populations,and the current state of vaccine research,considering the etiology,transmission,and prevention of the MPXV.Vaccination,as an effective method of epidemic prevention,can provide long-term immune protection and effectively reduce the severity of infection.However,as there is no licensed specific MPXV vaccine available globally,the vaccines currently used for mpox prevention are mostly smallpox vaccines.These smallpox vaccines can offer some degree of protection against mpox by activating cross-protection in the body.

超薄(~30μm)柔性钙钛矿/硅叠层太阳能电池

The efficiency of rigid perovskite/silicon tandem solar cells has reached 33.9%.However,there has been no report on flexible perovskite/silicon tandem solar cells due to the challenge of overcoming the poor light absorption of ultrathin silicon bottom cells while maintaining their mechanical flexibility.Herein,we report the first demonstration of the perovskite/silicon tandem solar cell based on flexible ultrathin silicon.We show that reducing the wafer thicknesses and feature sizes of the light-trapping textures can significantly improve the flexibility of silicon without sacrificing light utilization.In addition,the capping of the perovskite top cells can further improve the device's mechanical durability by shifting the neutral plane toward the silicon surface that is prone to fracture.Finally,the resulting ultrathin(~30μm)flexible perovskite/silicon tandem solar cell achieves a certified stabilized efficiency of 22.8%with an extremely high power-to-weight ratio of 3.12 W g^(-1).Moreover,the flexible tandems exhibit remarkable bending durability,maintaining 98.2%of their initial performance after 3000 bending cycles at a radius of only 1 cm.

A new metal-organic rotaxane framework for enhanced ion conductivity of solid-state electrolyte in lithium-metal batteries

The composite polymer electrolyte has been obtained via incorporating LiCUST-701(a new metal–organic rotaxane framework modified by Li+)into poly(ethylene oxide)(PEO)matrix and give a high ionic conductivity of 4.02×10^(−4)S/cm at 60℃.DFT calculations were used to visualize the possible diffusion pathway of Li+.The all-solid-state cell assembled with LiFePO_(4),composite polymer electrolyte and lithium metal foil delivered with excellent cycling capability and stability even under high current densities.

Highly emissive coordination polymer derived from tetraphenylethylene-tetrazole chromophore:Synthesis,characterization and piezochromic luminescent behavior

Solid-state materials that exhibit pressure stimulus-response characteristics in a manner of emission signal,known as piezochromic luminescence(PCL),demonstrate great potential in photoelectric devices.The weakened luminescence and insignificant color change in the aggregation state,however,hampers their practical applications.Herein,a highly emissive coordination polymer,[Zn2(H4TTPE)(H2O)4]·H2O(CUST-805),is successfully constructed by employing an AIE-active chromophore as the building block.The structural characterization and photophysical properties are systematically studied.Owing to intrinsic twisted conformation and AIE feature of tetraphenylethylene-tetrazole ligand,CUST-805 achieves the visible and reversible PCL from blue to green switched by different external stimuli.The transformation between crystalline and amorphous states is proved to be the origin of present PCL behavior.Moreover,on basis of electron and energy transfer quenching mechanism,the highly selective and sensitive sensor based on CUST-805 is realized,showing the low detection limit of 0.29 ppm towards 2,4,6-trinitrophenol.

Rational design of an AIE-active metal-organic framework for highly sensitive and portable sensing nitroaromatic explosives

Herein,we report a new metal-organic framework with an AIE ligand (H_(4)TCPP=2,3,5,6-tetra-(4-carboxyphenyl)pyrazine) and Mg^(2+) ions,that is,[Mg_(2)(H_(2)O)_(4)TCPP]·DMF·5CH_(3)CN (Mg-TCPP,TCPP=tetra-(4-carboxyphenyl)pyrazine) for detection of nitroaromatic explosives.Due to the coordination effect and restricted intramolecular rotation,Mg-TCPP exhibits bright blue light.As a fluorescent sensor,Mg-TCPP exhibits high selectivity and sensitivity for sensing 2,4,6-trinitrophenol (TNP) by quenching behaviors with the Stern-Volmer quenching constant (K_(SV)) of 3.63×10^(5)L/mol and achieves the low limit of detection of 25.6 ppb,which is beyond most of the previously reported fluorescent materials.Notably,the portable Mg-TCPP films are prepared and it can be used for rapid and sensitive TNP detection in a variety of environments including organic solvent and aqueous solution.Moreover,TNP vapor can be detected within 3 min by naked eye and the film could be regenerated under simple solvent cleaning.

DenseCL:A simple framework for self-supervised dense visual pre-training

Self-supervised learning aims to learn a universal feature representation without labels.To date,most existing self-supervised learning methods are designed and optimized for image classification.These pre-trained models can be sub-optimal for dense prediction tasks due to the discrepancy between image-level prediction and pixel-level prediction.To fill this gap,we aim to design an effective,dense self-supervised learning framework that directly works at the level of pixels(or local features)by taking into account the correspondence between local features.Specifically,we present dense contrastive learning(DenseCL),which implements self-supervised learning by optimizing a pairwise contrastive(dis)similarity loss at the pixel level between two views of input images.Compared to the supervised ImageNet pre-training and other self-supervised learning methods,our self-supervised DenseCL pretraining demonstrates consistently superior performance when transferring to downstream dense prediction tasks including object detection,semantic segmentation and instance segmentation.Specifically,our approach significantly outperforms the strong MoCo-v2 by 2.0%AP on PASCAL VOC object detection,1.1%AP on COCO object detection,0.9%AP on COCO instance segmentation,3.0%mIoU on PASCAL VOC semantic segmentation and 1.8%mIoU on Cityscapes semantic segmentation.The improvements are up to 3.5%AP and 8.8%mIoU over MoCo-v2,and 6.1%AP and 6.1%mIoU over supervised counterpart with frozen-backbone evaluation protocol.

磷酸二氢铵-磷酸氢二铵-聚磷酸铵-水四元体系相平衡的实验与计算

利用Schreinemaker湿渣法,通过离子色谱和质量守恒方程联立得到各组分在饱和液相和湿渣相中的分布,从而得到25℃下磷酸二氢铵-磷酸氢二铵-聚磷酸铵-水四元空间相图,解释了聚磷酸铵水溶液结晶、沉淀的问题,对聚磷酸铵作为高效水溶肥料使用、储存具有指导意义。同时为快速获得聚磷酸铵其他体系相图,引入电解质溶液局部组成模型回归了实验体系的溶剂(盐)-盐相互作用能量参数,通过回归参数计算所得的相图与实验相图吻合较好,可用于其他聚磷酸铵体系相图的预测。

立方八面体构型的多酸基金属-有机笼的合成与吸附染料性能

通过溶剂热方法合成一例具有立方八面体几何构型的多酸基金属-有机纳米分子笼:[NH2Me2]8{[V6O6(OCH3)9(SO4)]4(TATAB)4}·(MeOH)8(VMOP-20,H3TATAB为4,4′,4″-s-三嗪-1,3,5-三对氨基苯甲酸).该分子笼通过4个多金属钒酸盐建筑单元[V6O6(OCH3)9(SO4)]连接4个柔性有机配体H3TATAB通过共价键构成.每个八面体纳米分子笼通过C–H···π超分子作用力与周围相邻的8个多面体连接,形成三维超分子化合物.从网络拓扑学角度分析VMOP-20的超分子结构,如果将每一个纳米分子笼简化为八连接节点,VMOP-20则可以简化成具有bcu拓扑结构的三维超分子网络.在结构中含有3种不同尺寸和形状的一维隧道.通过单晶X射线衍射、粉末X射线衍射、红外光谱和热重分析等手段对该化合物进行表征.此外,由于VMOP-20分子笼具有电负性,还研究了其在甲醇溶液中对有机染料的吸附和分离性能,结果表明该化合物利用离子选择性吸附作用,在溶液中对阳离子染料有吸附作用而对于中性和阴离子染料不具备吸附能力,说明这种吸附是一种离子选择性交换原理.

Synthesis and characterization of two novel coordination polymers based on the rigid 1H-1,2,3-triazole-4,5-dicarboxylic acid ligand

Two novel three-dimensional (3-D) coordination polymers, [Pb(HTDA)]n (1) and [Co5(TDA)2(H2TDA)2(H2O)8]n (2) [H3TDA = 1H-1,2,3-triazole-4,5-dicarboxylic acid], have been prepared by hydrothermal reactions and characterized by elemental analysis, infrared spectroscopy and single-crystal X-ray diffraction. Compound 1 is constructed from rod-shaped secondary building units (SBUs) and exhibits a 3-D network with (410·65)(410·63·82) topology. Compound 2 is built up from ligands bridging three different cobalt ions and exhibits a 3-D network with (4·82)3(4·82·103) topology. In addition, the thermal stabilities of the two compounds, the photoluminescence properties of compound 1 and the magnetic properties of compound 2 have been studied.

Axially Chiral Dodecanuclear Lanthanide Clusters Constructed by“Bottom-Up” Self-assembly for Enantioselective Sensing

Via the bottom-up synthetic strategy,we synthesized a pair of dodecanuclear metal clusters of Eu_(12)(C_(2)O_(4))_(9)(R/S-BNP)_(18)(EtOH)_(6)-(H_(2)0)_(6)·8EtOH-7H_(2)0(complex 2),which represent the largest axial chiral lanthanide metal clusters.In the structure,rare four-pointed star coordination mode of oxalic acid is reported by this work.In addition,as a fluorescence sensor,the complex 2 exhibits high enantioselectivity for R-/S-BINOL-TF_(2)(EF=2.87)and other chiral binaphthyl derivatives.

Stepwise Construction of Multivariate Metal–Organic Frameworks from a Predesigned Zr16 Cluster

A series of multivariate metal-organic frameworks(MOFs)with predictable topologies are stepwise constructed from a predesigned versatile hexadecnuclear zirconium cluster.The[Zr_(16)]cluster is constructed from a center classic[Zr_(6)(μ_(3)-OH)_(4)(μ_(3)-O)_(4)(COO)_(4)]cluster and two capped[Zr_(5)(μ_(3)-OH)_(4)(μ2-O)_(4)(HSQA)_(4)(DMF)_(4)](SQA=squaric acid,DMF=dimethylformamide)clusters which have 24 potential coordination sites to link metal ions and four formate groups to be substituted by other organic ligands.Based on this predesigned cluster.