On the Preparation of Low-Temperature-Rise and Low-Shrinkage Concrete Based on Phosphorus Slag

The effects of different contents of a MgO expansive agent and phosphorus slag on the mechanical properties,shrinkage behavior,and the heat of hydration of concrete were studied.The slump flow,setting time,dry shrinkage,and hydration heat were used as sensitive parameters to assess the response of the considered specimens.As shown by the results,in general,with an increase in the phosphorus slag content,the hydration heat of concrete decreases for all ages,but the early strength displays a downward trend and the dry shrinkage rate increases.The 90-d strength and dry shrinkage of concrete could be improved with a phosphorus residue content between 0%-20%,with the best performances in terms of mechanical properties and shrinkage characteristics being achieved for a content of 20 kg/m^(3).On the basis of these results,it can be concluded that appropriate amounts of phosphorus slag and MgO expansive agent can be used to improve the compressive strength of concrete in the later stage by reducing the hydration heat and dry shrinkage rate,respectively.

Different response of North Pacific storm tracks in the upper and lower troposphere to jet strength

北太平洋风暴轴的深冬抑制表明风暴轴强度与斜压性之间的线性关系在冬季破裂,本研究基于1979-2019年冷季的再分析数据和拉格朗日跟踪算法,对比分析了高低层扰动的具体生长过程,结果表明太平洋急流的增强有利于高层扰动在急流核东北侧产生,但却抑制其在西北太平洋的生成,在急流核上游产生的高层扰动在整个冷季都无法充分发展,只有在急流核下游产生的高层扰动才能正常生长且它们是构成高层太平洋风暴轴的主体,相比之下,低层扰动的生成区和生长区都与斜压区重合,并且它们的生成数量和局部增长率随着斜压性的增强而增强.

Analysis of a Composite Admixture Based on Ready-Mixed Concrete Waste Residuals

Reasonable treatment and utilization of waste residuals discharged during the production of ready-mixed concrete is an important problem in the cement industry.In this study,a composite admixture was prepared by using ready-mixed concrete waste residuals,furnace slag,and water granulated slag.The grinding characteristics of such material were investigated.Moreover,the effect of such admixture on cement hydration and pore structure was analyzed by X-ray diffraction,thermogravimetric-differential scanning calorimetry,scanning electron microcopy and mercury intrusion porosimetry.As shown by the results:The grinding characteristics of the waste residuals can be improved significantly by mixing them with furnace slag and water granulated slag.Furthermore,the composite admixture does not change the composition of hydration products;rather it contributes to refine the pore structure of the matrix,thus improving the mechanical properties of these cement-based materials.

A new D–D–π–A dye for efficient dye-sensitized solar cells

New metal-free organic dye sensitizers containing mono-triphenylamine or bis-triphenylamine as the electron donor, a thiophene as the π-conjugated system, and a cyanoacrylic acid moiety as the electron acceptor were synthesized. The optical and electrochemical properties of the dyes were investigated,and their performance as sensitizers in solar cells was evaluated. Dye-sensitized solar cells based on dye containing bis-triphenylamine as the electron donor produced a photon-to-current conversion efficiency of 6.06%（Jsc = 14.21 m A/cm;, Voc = 0.62 V, ff = 0.69） under 100 m W/cm;simulated AM 1.5 G solar irradiation（100 m W/cm;）.

Suzuki reaction of bromoallenes with arylboronic acids using an air-stable palladium complex Pd(Ph_2PCH_2CO_2)_2 as a precatalyst

Suzuki reaction of bromoallenes with arylboronic acids was successfully performed by using an air-stable hemilabile P-O coordinated cyclopalladated complex Pd(Ph_2PCH_2CO_2)_2 as a precatalyst,and the corresponding coupling products were obtained in satisfactory to excellent yields.All products are unknown compounds which were characterized by ~1H NMR,^(13)C NMR,IR,and HRMS.

Preparation of microcapsule-supported palladium catalyst using SPG (Shirasu Porous Glass)emulsification technique

A new method for the preparation of microcapsule-supported palladium catalyst was described.The highly monodisperse crosslinked polystyrene microcapsules containing phosphine ligand were synthesized by the self-assembling of phase separated polymer （SaPSeP） method using diphenyl（4-vinylphenyl） phosphine and divinylbenzene as a monomer and crosslinking agent,respectively, and 2,2＇-azobisisobutyronitrile（AIBN） as an initiator within the droplets of oil-in-water（O/W） emulsions,which were prepared by using the Shirasu Porous Glass（SPG） membrane emulsification technique.The prepared microcapsule-supported palladium catalyst exhibited high catalytic activity for Heck reaction and can be reused several times without loss of activity.

Performance Improvement of Dye-Sensitized Solar Cell by Phenanthrothiadiazole Unit-Based π-Conjugated Bridge

New organic dyes (D1, D2, and D3) containing a phenanthrothiadiazole unit as a π-conjugated system, a triarylamine as an electron donor, and a cyanoacrylic acid moiety as an electron acceptor were synthesized. The optical and electrochemical properties of dyes D1, D2, and D3 were investigated, and their performance as sensitizers in solar cells was evaluated. Dye-sensitized solar cells based on dye D3 produced a photon-to-current conversion efficiency of 5.23% (Jsc = 9.70 mA/cm2, Voc = 0.77 V, ff 0.70) under 100 mW/cm2 simulated AM 1.5 G solar irradiation.

Li Yiping:Dedicated to Chinese Culture Going Global

The year 2021 is assuredly an wonderful year for China Cultural Center(CCC)in Laos and its Director Li Yiping.The China-Laos Year of Friendship will be celebrated,the new CCC in Laos building will be put into use,and many fascinating cultural events will be launched.All these highlight moments are awaiting kickoff by Li Yiping and her colleagues.

AFRICA‘Happy Chinese New Year’Celebrations Promoting China-Africa Enduring Friendship

The year 2021 marks the 50th anniversary of China-Nigeria diplomatic ties."Share the Moment Together:Gala Performance in Celebration of the 50th Anniversary of the Establishment of Diplomatic Relations between China and Nigeria",co-organized by China's Ministry of Culture and Tourism and Nigeria's Ministry of Information and Culture was livestreamed at several online platforms.

AMERICA‘Happy Chinese New Year’Celebrated in the Americas

China's overseas missions organized diverse cultural events to celebrate Chinese New Year in Panama,Costa Rica,Canada,the United States,Mexico,Brazil and Peru.Variety shows,animation pictures,arts competitions,and exhibitions were presented under the"Happy Chinese New Year"series.

Gansu Culture and Tourism Week Launched in China Cultural Center in Laos

In celebration of the 60th anniversary of China-Laos diplomatic ties and the China-Laos Friendship Year in 2021,China Cultural Center(CCC)in Laos has organized a great variety of events to enhance cultural exchanges and promote tourism resources.From August 16 to 21,the Gansu Culture and Tourism Week took place in Laos under the guidance of the Chinese Ministry of Culture and Tourism,co-organized by CCC in Laos and Gansu Provincial Department of Culture and Tourism.

Discrete element method study of parameter optimization and particle mixing behaviour in a soil mixer

Soil mixing is an emerging research in the field of construction resource recovery.In this study,the mixing behaviour of soil particles in a mixer is numerically simulated by the discrete element method(DEM).A four-factor,three-level orthogonal experiment is designed to optimize the mixer design by selecting the fly-cutter speed,spindle speed,number of blades and fly-cutter diameter,using Lacey mixing index and power consumption as evaluation indicators.Then,the impact of soil cohesion and type on the mixing behaviour is investigated.The results show that the optimal parameter combination of this experiment is 280 rpm fly-cutter speed,40 rpm spindle speed,4 blades and 250 mm fly-cutter diameter.This optimal combination reaches a comparatively uniform state mix in 5.9 s with an average power consumption of 704.11 W.In addition,the wear and tear of the mixer increases as soil cohesion increases,while the mixing quality of materials declines,resulting in a“shaft hugging”phenomenon.The mixing efficiency varies greatly among different soil types,but the radial and tangential velocities have a similar law.This work can provide some guidance for the optimization design of a mixer and study of soil mixing.

Preparation and application of SBA-15-supported palladium catalyst for Heck reaction in supercritical carbon dioxide

A new method for the preparation of SBA-15-supported palladium catalyst for Heck reaction in supercritical carbon dioxide was presented.The newly formed SBA-15-supported palladium catalyst（Ph-SBA-15-PPh_3-Pd） exhibited high catalytic activity for the Heck reaction of 4-nitrobromobenzene with methyl acrylate.The catalyst can be reused several times without a loss of activity.

Gold-catalyzed ketene dual functionalization and mechanistic insights:divergent synthesis of indenes and benzo[d]oxepines

An unprecedented gold-catalyzed ketene C=O/C=C bifunctionalization method has been developed.Mechanistic studies and density function theory(DFT)calculations indicate that the reaction is initiated by gold-catalyzed Wolff rearrangement of diazoketone to form the ketene intermediate,followed by intermolecular nucleophilic addition and terminated with two divergent cyclization processes via enol intermediates.In the case with alcohols as the nucleophiles,the reaction goes through a C-5-endodig carbocyclization to give the indene products;whereas,O-7-endo-dig cyclization occurs dominantly when indoles/pyrroles are used as the nucleophiles,delivering the 7-membered benzo[d]oxepines.In comparison with the well-documented cycloaddition and nucleophilic addition reactions,this cascade reaction features a novel reaction pattern for the ketene dual functionalization through addition with nucleophile and electrophile in sequence.

Recent advances in gold-complex and chiral organocatalyst cooperative catalysis for asymmetric alkyne functionalization

Homogeneous gold catalysis has demonstrated the preponderant capability of realizing a broad range of synthetically versatile alkyne functionalization over the last two decades.Though catalytic asymmetric alkyne transformation has focused on the principle of using gold catalysts either associated with chiral phosphine ligand or combined with chiral counterion,a variety of breakthroughs have been reported with the application of gold-complex and chiral organocatalyst cooperative catalysis strategy,which could enable the challenging transformations that cannot be realized by mono-catalysis with excellent stereoselectivity.This review will cover two general protocols in this field,including relay catalysis and synergistic catalysis,with emphasis on the detailed cooperative catalysts models to illustrate the roles of the two catalysts and highlight the potential synthetic opportunities offered by asymmetric cooperative catalysis.

Synthesis of 5-vinyl-2-norbornene through Diels-Alder reaction of cyclopentadiene with 1,3-butadiene in supercritical carbon dioxide

An efficient method for the synthesis of 5-vinyl-2-norbornene from cyclopentadiene and 1,3-butadiene was developed.The Diels-Alder reaction of cyclopentadiene with 1,3-butadiene proceeded smoothly in supercritical carbon dioxide in the absence of any polymerization inhibitor to produce the corresponding5-vinyl-2-norbornene in satisfactory yield with high selectivity.

Linking of Chemical Reactions and Silica Nanoparticle Contact Using Synthetic Helical Molecules

Biological cells exhibit diverse phenomena induced through linking of chemical reactions of molecules and solid surface contact.It is then a significant topic in the field of chemistry to study phenomena induced through this linking using synthetic systems,which can promote our understanding of biological phenomena and can be applied to the development of novel functions.Silica nanoparticles(sNPs),which are synthetic inorganic materials,are attractive for such purposes,because of their following characteristics:they can adsorb large amounts of molecules on their surfaces,they can aggregate through contact between SNPs as well as contact between molecules and SNPs,and the molecules can be easily removed from solutions by precipitation.The contact of sNP surfaces with molecules then affects chemical reactions of molecules and also behaviors of sNPs.This article describes systems derived from synthetic helical molecules and sNPs,which exhibit notable phenomena including selective adsorption and molecular recognition,equilibrium shift,step kinetics with induction period,precipitation with flow and sweeping,and disaggregation and desorption by sonication,in which the high affinity of helical molecules with sNP surfaces plays important roles.Mechanistic models that explain the phenomena are provided.Possible applications are also discussed,including the separation of molecules,capture of intermediates,the storage and release of molecules,equilibrium shift,clocking,and the translation of mechanical stimulations into chemical reactions.