Understanding the combustion behavior of electric bicycle batteries and unveiling its relationship with fire extinguishing

In this study,a detailed analysis of the combustion behaviors of the lithium iron phosphate(LFP)and lithium manganese oxide(LMO)batteries used in electric bicycles was conducted.This research included quantitative measurements of the combustion duration,flame height,combustion temperature,heat release rate,and total heat release.The results indicated that LMO batteries exhibited higher combustion temperatures of 600–700°C,flame heights of 70–75 cm,a significantly higher heat release rate of40.1 k W(12 Ah),and a total heat release of 1.04 MJ(12 Ah)compared to LFP batteries with the same capacity.Based on these experimental results,a normalized total heat release(NORTHR)parameter was proposed,demonstrating good universality for batteries with different capacities.Utilizing this parameter,quantitative calculations and optimization of the extinguishing agent dosage were conducted for fires involving these two types of batteries,and the method was validated by extinguishing fires for these two types of battery packs with water-based extinguishing fluids.

Amorphous and humidity caking: A review

Caking of products is a common and undesired phenomenon in food, chemical, pharmaceutical, and fertilizer industries which leads to extra cost and irregular quality. In general, caking processes could be identified as amorphous caking or humidity caking. In this review, history of studying caking, formation, methods, and prospects of these two caking processes are summarized and discussed. The relevant studies from the 1920 s to today are mentioned briefly. According to the different properties(i.e. hygrocapacity, hygrosensitivity, mechanical properties, and diffusion behavior) of amorphous powders and crystals, the conditions and mechanisms of amorphous and humidity caking are discussed. It is summarized that glass transition, moisture sorption, quantitative methods characterizing caking, accelerated caking tests, and simulation of caking behaviors are the main aspects that should be studied for a caking process. The methods for these five aspects are reviewed. Potential research points are proposed including caking of mixed particles, caking with phase transition or polymorph transition,non-homogenous caking, and simulation of caking.

Efficient Catalytic Conversion of Polysulfides by Biomimetic Design of “Branch‑Leaf” Electrode for High‑Energy Sodium–Sulfur Batteries

Rechargeable room temperature sodium–sulfur(RT Na–S)batteries are seriously limited by low sulfur utilization and sluggish electrochemical reaction activity of polysulfide intermediates.Herein,a 3D“branch-leaf”biomimetic design proposed for high performance Na–S batteries,where the leaves constructed from Co nanoparticles on carbon nanofibers(CNF)are fully to expose the active sites of Co.The CNF network acts as conductive“branches”to ensure adequate electron and electrolyte supply for the Co leaves.As an effective electrocatalytic battery system,the 3D“branch-leaf”conductive network with abundant active sites and voids can effectively trap polysulfides and provide plentiful electron/ions pathways for electrochemical reaction.DFT calculation reveals that the Co nanoparticles can induce the formation of a unique Co–S–Na molecular layer on the Co surface,which can enable a fast reduction reaction of the polysulfides.Therefore,the prepared“branch-leaf”CNF-L@Co/S electrode exhibits a high initial specific capacity of 1201 mAh g^−1 at 0.1 C and superior rate performance.

Terahertz metasurface zone plates with arbitrary polarizations to a fixed polarization conversion

Metasurfaces that can realize the polarization manipulation of electromagnetic waves on the sub-wavelength scale have become an emerging research field.Here,a novel strategy of combining the metasurface and Fresnel zone plate to form a metasurface zone plate is proposed to realize the conversion from nearly arbitrary polarizations to a fixed polarization.Specifically,when one polarized wave is incident on adjacent ring zones constructed by different types of meta-atoms,the transmitted waves generated by odd-numbered and even-numbered ring zones converge at the same focus and superimpose to generate a fixed polarized wave.As function demonstrations,we have designed two types of metasurface zone plates:one is a focused linear polarizer,and the other can convert nearly arbitrary polarized waves into focused circularly polarized waves.The simulated and measured results are consistent with theoretical expectations,suggesting that the proposed concept is flexible and feasible.Our work provides an alternative platform for polarization manipulation and may vigorously promote the development of polarization photonic devices.

Cloning and molecular evolution of 9-cis-epoxycarotenoid dioxygenase gene (NCED3) in six species of Glycyrrhiza L

Objective:To understand the evolutionary relationship of NCED3 in Glycyrrhiza L.and find genetic evidence of its local adaptation.Meanwhile,lay the foundation for relieving the demand and subsequent starvation of Glycyrrhiza resources.Methods:NCED3 were isolated from six species of Glycyrrhiza L.by rapid amplification of cDNA ends and a homology cloning strategy.The basic properties and evolutionary relationships of NCED3 were analyzed by bioinformatics.Results:Six NCED3 genes formed two clusters;they were under purifying selection and were highly conserved in evolution (Ka/Ks≤).There was very little functional divergence among the NCED3s (Alpha value 0.071).The contents of ABA in the six species were divided into two groups.Conclusion:This study provides the first analysis of the evolution of NCED3s in six species of Glycyrrhiza.Six NCED3 genes were slow evolutionary rates in six NCED3s.Different genetic relationships to Glycyrrhiza adapted to various environments.The changes in ABA content were consistent with the evolution of NCED3.Whether there are direct relationships between NCED3 and environmental adaptation,the answer is uncertain,and we hope to show more positive results in the further study of NCED3 in Glycyrrhiza L.

Concentrated ternary ether electrolyte allows for stable cycling of a lithium metal battery with commercial mass loading high-nickel NMC and thin anodes

A new concentrated ternary salt ether-based electrolyte enables stable cycling of lithium metal battery(LMB)cells with high-mass-loading(13.8 mg cm^(−2),2.5 mAh cm^(−2))NMC622(LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2))cathodes and 50μm Li anodes.Termed“CETHER-3,”this electrolyte is based on LiTFSI,LiDFOB,and LiBF4 with 5 vol%fluorinated ethylene carbonate in 1,2-dimethoxyethane.Commer-cial carbonate and state-of-the-art binary salt ether electrolytes were also tested as baselines.With CETHER-3,the electrochemical performance of the full-cell battery is among the most favorably reported in terms of high-voltage cycling stability.For example,LiNi_(x)Mn_(y)Co_(1-x-y)O_(2)(NMC)-Li metal cells retain 80%capacity at 430 cycles with a 4.4 V cut-off and 83%capacity at 100 cycles with a 4.5 V cut-off(charge at C/5,discharge at C/2).According to simulation by density functional theory and molecular dynamics,this favorable performance is an outcome of enhanced coordination between Li^(+)and the solvent/salt molecules.Combining advanced microscopy(high-resolution transmission electron microscopy,scanning electron microscopy)and surface science(X-ray photoelectron spectroscopy,time-of-fight secondary ion mass spectroscopy,Fourier-transform infrared spectroscopy,Raman spectroscopy),it is demonstrated that a thinner and more stable cathode electrolyte interphase(CEI)and solid electrolyte interphase(SEI)are formed.The CEI is rich in lithium sulfide(Li_(2)SO_(3)),while the SEI is rich in Li_(3)N and LiF.During cycling,the CEI/SEI suppresses both the deleterious transformation of the cathode R-3m layered near-surface structure into disordered rock salt and the growth of lithium metal dendrites.

The Difference of Lemma Activation Between Native Speakers of English and L2 Speakers of English With L1 Chinese:Evidence From the Semantic and Phonological Priming Effects on L2 Speech Planning

This study examined the influence of semantic and phonological priming on L2 speech planning,as well as the difference between native and non-native speakers of English in terms of lemma activation.Two potential explanations for the contrast between the performance of L2 speakers and native controls were considered.The first of which was that L2 speakers’ phonological forms are activated before selection of syntactic frame occurred,whereas the reverse is true for native speakers.The second explanation posits that the organisation of the speech production procedure is fundamentally similar in native and L2 speakers,and the disparity in performance arises from difference in the levels of activation of stored items.The results of the present experiment suggest that lemma selection is indeed what drives syntactic frame selection.However,lemmas in L2 speakers can be primed through a chain of connections demonstrated as:L2 phonological form →L1 phonological form → L1 lemma.

Cocrystals of carbamazepine:Structure,mechanical properties,fluorescence properties,solubility,and dissolution rate

Carbamazepine(CBZ)is an anticonvulsant with very low water solubility,presenting as a white crystalline powder with poor mechanical properties and is hard to bend.To enhance CBZ's physicochemical properties,such as water solubility and mechanical properties,we selected six cocrystal coformers(CCFs):nicotinamide(NIC),benzamide(BZM),salicylic acid(SCA),fumaric acid(FMA),trimesic acid(TMA),and hesperetin(HPE).Six CBZ cocrystals were successfully prepared using the solution method.Fourier transform infrared spectroscopy(FT-IR),powder X-ray diffraction(PXRD),differential scanning calorimetry(DSC),and single crystal X-ray diffraction(SCXRD)were used to characterize the crystal structures and gain comprehensive insights into the six cocrystals.The mechanical,fluorescence,and solubility properties of the six cocrystals were tested.The results reveal that most of the prepared cocrystals exhibit improved water solubility and mechanical properties when compared to CBZ.Among them,the dissolution rate of cocrystals excluded from CBZ-HPE has increased by an average of 3 or 4 times compared to CBZ,while CBZ-HPE exhibits superior mechanical properties.Moreover,all six cocrystals possess better fluorescence performance than CBZ.We thoroughly evaluated the mechanical properties of the cocrystals through both experimental and theoretical approaches.This work provides a new direction for studying drug cocrystals to improve the physicochemical properties of drugs.

High Strength and Heat Resistance of Low-RE-Containing Mg Alloy Achieved via Substantial Dynamic Precipitates

Conventional high-strength Mg-RE-based wrought alloys usually contain a high amount of RE solutes,which largely increases the alloy cost and thus restricts their adoptions.In this work,we developed a low-RE-containing Mg-3Sm-1Nd-0.6Zn-0.4Zr alloy by hot extrusion with low extrusion ratio,which shows a high tensile yield strength(TYS)of 435 MPa and a satisfactory elongation of 5.6%at room temperature,outperforming most Mg-Gd-Y-based extrusion alloys with RE contents of 12 wt%at least.Outstanding high-temperature strength,such as the TYS of 280 MPa at 200℃ and 251 MPa at 250℃,is also obtained in this alloy.The alloy presented a typical bimodal grain structure including coarse hot-worked grains with a strong texture and fine recrystallized grains with random orientations.Also,abundant Mg3RE particles were mostly introduced in hot-worked grains and at recrystallized grain boundaries by dynamic precipitation during extrusion.Consequently,the high strength of this alloy is principally attributed to the combined hardening effect of numerous Mg_(3)RE particles,fine recrystallized grains,and strongly textural hot-worked grains,rather than the ultra-strong age-hardening effect in traditional high RE-alloyed Mg alloys.

智慧教育视域下混合式学习空间的构建与实践研究

智慧教育概念的提出和信息技术的不断深入发展,为广播电视大学系统远程教育改革提供了新思路与新方法。文章在界定智慧教育与混合式学习空间核心概念的基础上构建了混合式学习空间模型,阐述了其关键技术,试图在智慧教育理念引领下构建一种将方法、技术、资源融为一体的混合式学习空间,并利用其在大数据教学分析、空间联动、课程教学改革、党建与思政课等方面进行了积极探索,有效促进了广播电视大学系统远程教育改革。

Manipulation of polarization conversion and multiplexing via all-silicon phase-modulated metasurfaces

Phase-modulated metasurfaces that can implement the independent manipulation of co-and cross-polarized output waves under circularly polarized[CP]incidence have been proposed.With this,we introduce one particular metasurface composed of meta-atoms with a phase difference of 2π/3 to generate specific elliptically polarized waves under various polarized incidences.Furthermore,a metasurface composed of these above meta-atoms and the meta-atoms with a phase difference of π/3 arranged in a certain rule can realize polarization conversion function between linearly polarized and CP states.The designs shed new light on multifarious optical devices and may further promote the development of metasurface polarization optics.

Selectivity switch in transformation of CO2 from ethanol to methanol on Cu embedded in the defect carbon

The copper-based catalysts have been generally regarded as high-performance catalysts for CO_2 hydrogenation toward methanol,while the production of ethanol via C–C coupling on the copper-based catalysts is still challenging.Herein,we report a new catalyst where Cu nanoparticles are embedded in the carbon support with abundant defect sites,achieving a high selectivity for ethanol in the CO_2 hydrogenation.The experiments coupled with the theoretical studies show a clear map where carbon defects serve as anchor sites that can stabilize interfacial copper species,and interfacial Cu sites with low coordination numbers can adsorb two C_1 species and later convert them to a C_2 species via a hydrogenation-induced coupling reaction.Further adjacent Cu atoms of interfacial Cu sites can facilitate OH reduction reactions via the Cu–Cu bridge adsorption to assist the formation of ethanol.Especially,those specific active sites easily disappear in the reducing conditions and during the reaction,the major product can transform from ethanol to methanol.

Machine learning-based solubility prediction and methodology evaluation of active pharmaceutical ingredients in industrial crystallization

Solubility has been widely regarded as a fundamental property of small molecule drugs and drug candidates,as it has a profound impact on the crystallization process.Solubility prediction,as an alternative to experiments which can reduce waste and improve crystallization process efficiency,has attracted increasing attention.However,there are still many urgent challenges thus far.Herein we used seven descriptors based on understanding dissolution behavior to establish two solubility prediction models by machine learning algorithms.The solubility data of 120 active pharmaceutical ingredients(APIs)in ethanol were considered in the prediction models,which were constructed by random decision forests and artificial neural network with optimized data structure and model accuracy.Furthermore,a comparison with traditional prediction methods including the modified solubility equation and the quantitative structure-property relationships model was carried out.The highest accuracy shown by the testing set proves that the ML models have the best solubility prediction ability.Multiple linear regression and stepwise regression were used to further investigate the critical factor in determining solubility value.The results revealed that the API properties and the solute-solvent interaction both provide a nonnegligible contribution to the solubility value.

Tuning Selectivity in Catalytic Conversion of CO_(2) by One-Atom-Switching of Au9 and Au8Pd1 Catalysts

The optimization of catalysts for CO_(2) hydrogenation that is carried out in a traditional fixed-bed reactor predominantly focuses on pursuing various nanoparticles at the nanoscale.Much less is known about how heterogeneous catalysts can be exploited to precisely control the reaction pathways of CO_(2) conversion at the atomic level.

Mechanism and inhibition of trisodium phosphate particle caking： Effect of particle shape and solubility

We investigated the influence of particle shape and solubility on the caking behavior of trisodium phosphate by considering the adhesion free energy and crystal bridge theory. Caking of trisodium phosphate during the drying process under static conditions is a two-step process： adhesion followed by crystal bridge formation between particles. The adhesion free energy plays an important role in adhesion. Trisodium phosphate particles cannot adhere to each other and cake when the adhesion free energy is greater than a critical value, which varies with particle shape. Compared with granular particles, cylindrical particles have larger contact area between particles, which results in more crystal bridges forming and a higher caking ratio. Thus, the critical value is about 100 mJ/m^2 for cylindrical particles, but 60 mJ/m^2 for granular particles at 25 ℃. Concerning the solubility, when particles are similar shapes and soluble in the rinsing liquid, the caking ratio has a linear relationship with adhesion free energy. However, if the particles are insoluble in the rinsing liquid, caking can be completely prevented regardless of adhesion free energy because no crystal bridges form during the growth process. Hence, caking of trisodium phosphate particles could be inhibited by screening rinsing liquids, and optimizing the particle shape and size distribution.

Design spherical particles of potassium peroxymonosulfate compound salt with high stability and good powder properties via an agglomeration-dissolution mechanism

With the outbreak of COVID-19,disinfection protection has become a necessary measure to prevent infection.As a new type of disinfectant,potassium peroxymonosulfate compound salt(PMS)has the advantages of good bactericidal effect,non-toxicity,high safety and stability.However,the current PMS products with irregular particle shapes lead to poor flowability,high hygroscopicity,poor stability of reactive oxygen species(ROS)and serious caking problems.In this work,an agglomeration-dissolution mechanism was designed to prepare spherical PMS particles with large size(>300μm)and high sphericity(up to 90%),effectively addressing the above problems.Shaping(dissolution and abrasion)is the key to improving sphericity,which is mainly controlled by the design of the heating mode,residence time and stirring rate.Compared with the irregular PMS particles,the large spherical particles present better flowability(angle of repose decreased by 35.80%,Carr's index decreased by 64.29%,Hausner's ratio decreased by 19.14%),lower hygroscopicity(decreased by 38.0%),lower caking ratio(decreased by 84.50%),and higher stability(the monthly loss of ROS was reduced by 61.68%).The agglomeration-dissolution mechanism demonstrates the crystallization,agglomeration,dissolution and abrasion process of inorganic salt crystals,providing an opportunity to prepare high-end inorganic crystal materials with high-quality morphologies.

Intramolecular hydroamination of alkynes driven by isomeric Au_(36)(SR)_(24)nanocluster catalysts

It remains elusive to realize the distinct catalysis of isomeric catalysts because it becomes challenging to identify structural isomers in the polydisperse nanoparticles.Herein we investigate catalysis of two geometric isomers for 36-gold-atom nanoclusters with different Au cores arrangements but the same thiolate ligands,thereby providing access to isomer catalysts readily participate in a desired reaction.Compared to the Au_(36)(SR)_(24)with a one-dimensional(1D)layout of Au4 tetrahedral units,the Au_(36)(SR)_(24)with a two-dimensional(2D)layout of Au4 tetrahedral units is more effective for the intramolecular hydroamination of alkyne.Our study suggests that the exposed Au sties of the two Au_(36)(SR)_(24)catalysts favor different reaction intermediates and pathways.The intramolecular H transfer leads to intermediates with the C-N and with C=N for the 1D and 2D Au_(36)(SR)_(24)respectively,and hence the different on-site and off-site pathways for the successive reaction steps account for the different performances of the two Au_(36)(SR)_(24)catalysts.

Visible-Light-Driven Methane Conversion with Oxygen Enabled by Atomically Precise Nickel Catalyst

It remains an extreme challenge to activate thermodynamically unfavorable,chemically inert methane molecules under mild conditions.Herein,we report a molecular-like nickel-thiolate hexameric cluster[Ni_(6)(PET)_(12);PET=SC_(2)H_(4)Ph]catalyst that resembles a double crown,comprising of a hexagonal Ni6 kernel encapsulated by an exterior shell of 12 thiolates capable of efficient conversion of methane plus O_(2) to methanol and formic acid under visible light irradiation.

The atomic path for constructing single-helical superstructure of AuCu bimetallic nanoclusters

Single-helical or double-helical structures are common in living organisms.Helical assembly has been found in the artificial nanoparticles,but how they do so remains poorly understood.Here,we exploit atomically precise Au_(6)Cu_(6)bimetallic nanoparticles(or called nanoclusters)as building blocks to construct a single-helical Au_(12)Cu_(12)superstructure in an operative path,thereby providing access to currently elusive mechanistic pathways.We propose that the thermodynamically viable linearto-bent process at a couple of Au_(6)Cu_(6)nanoclusters imparted by the organic ligands seems to be critical for the helical-nanostructured arrangement of Au_(12)Cu_(12).This study could help to offer a new design rule for the exquisitely helical structure assembled from the artificial nanoparticles.

Particle size distribution design of limited agglomeration via geometric morphology in erythritol crystallization

Regarding sugar and salt crystallization with large single crystals,the agglomerate thermodynamics and geometric morphologies,not the dynamics,dominate the particle size distribution(PSD).To consider this issue,a PSD design model is proposed for limited large crystal agglomeration.In this model,the agglomeration thermodynamic criticality is determined by estimating the adhesion and dispersion forces between single crystals.The geometric agglomerate morphologies are described by corresponding single crystal units stacking with porosity.By seed well-controlled of population,the key parameters of PSD(D01,D50 and D99)are precisely designed.For erythritol,the model design accuracies are 92%–99%in the 1.2 L and 10 L crystallizers,indicating that it can design PSD at various crystallization scales.Concerning the general research attention to microcrystal agglomeration kinetics(mostly active pharmaceutical ingredients),this model effectively guides the sugar and salt PSD design with limited large crystal agglomeration.