Polypropylene(PP) accounts for approximately 28.0% of the global polyolefin market,valued at $243.4 billion in 2022.Known for its lightweight,chemical resistance,costeffectiveness,high strength and melting point,PP is...Polypropylene(PP) accounts for approximately 28.0% of the global polyolefin market,valued at $243.4 billion in 2022.Known for its lightweight,chemical resistance,costeffectiveness,high strength and melting point,PP is widely used in various applications.Its properties and applications are closely tied to its tacticity.One-dimensional(1D) conventional 13C NMR has been extensively utilized to analyze PP tacticity,but its low sensitivity and longer relaxation time remain drawbacks.Typically,analyzing a single PP sample requires around 9 h of NMR time.Using of a cryogenically cooled 10 mm NMR probe can significantly reduce this measurement time;however,its high cost makes it inaccessible for most NMR laboratories.While the refocused insensitive nuclei enhanced by polarization transfer(RINEPT) technique is well-known for enhancing NMR sensitivity,there are no published studies using 1D 13C RINEPT to quantify PP tacticity.Relaxation agents like chromium(Ⅲ) acetylacetonate(Cr(acac)_(3)) have also been used to reduce relaxation times in polyolefin NMR analyses.Here we introduce a straightforward and easily implementable 1D 13C NMR method for rapid PP tacticity quantification.This method combines Cr(acac)_(3),Bruker's existing RINEPT pulse sequence(ineptrd),and our recently published ~1H decoupling sequence(bi_waltz65_256 pl) to eliminate ~1H decoupling artifacts.It is worth noting that decoupling artifacts are always present.When the signal-to-noise ratio(SNR) is low,these artifacts are obscured by noise.For example,in some two-dimensional(2D) or three-dimensional(3D) NMR spectra,decoupling artifacts are barely visible because of the low SNR.However,when attempting to observe weak signals in ~1D spectra,increasing the sample concentration or the number of scans enhances the SNR,revealing the decoupling artifacts.The decoupling artifacts appeared superimpose with some other weak signals,affecting the measurements of signal intensities.Therefore,improved ~1H-decoupling methods are crucial for such data acquisitio n.This synergy results in a 9.4-to 9.7-fold sensitivity enhancement,equating to an 88-to 94-fold reduction(9.4^(2)≈88,9.7^(2)≈94) in NMR acquisition time compared to conventional 1D 13C NMR experiment with Cr(acac)_3.The time savings are even more substantial compared to experiments without Cr(acac)_3.The faster and quantitative approach is accessible to researchers with or without cryoprobes.Beyond PP,this method can be applied to tacticity measurements of other polyolefins,such as polybutene,polyhexene and polyoctene.展开更多
Propylene was polymerized with a novel supported Ziegler-Natta catalystcontaining 2,2-di-iso-butyl-1,3-dimethoxy-propane (DIBDMP) as internal donor and in theabsence of external donor. The tacticity distribution of po...Propylene was polymerized with a novel supported Ziegler-Natta catalystcontaining 2,2-di-iso-butyl-1,3-dimethoxy-propane (DIBDMP) as internal donor and in theabsence of external donor. The tacticity distribution of polypropylene was obtained by usingtemperature rising elution fractionation (TREF) technique and microstructure of fractionswas studied with ^(13)C-NMR. Compared with the catalyst without electron donor, this cat-alyst gives a considerably narrower tacticity distribution. Fractionation data demonstratethat DIBDMP shows better performance than aromatic diester DNBP (di-n-butyl phtha-late). Chemically inverted propylene units and less stereoblockiness are found in the firstfraction. Possible reasons for these were presented.展开更多
After tentative ring-opening cross metathesis （ROCM） of endo-bicyclo[3.2.0]hept-6-en-3-yl 4-bromobenzoate with PhCH = CH2 initiated by （Cy3P）2Cl2Ru = CHPh in CH2Cl2, ring-opening metathesis polymerization （ROMP）...After tentative ring-opening cross metathesis （ROCM） of endo-bicyclo[3.2.0]hept-6-en-3-yl 4-bromobenzoate with PhCH = CH2 initiated by （Cy3P）2Cl2Ru = CHPh in CH2Cl2, ring-opening metathesis polymerization （ROMP） of a series of endo-bicyclo[3.2.0]hept-6-en-3-yl benzoates was achieved under the same conditions, furnishing a variety of the corresponding polymers. Then some of them were selected to hydrogenate the C=C double bonds in their backbone with p-tosylhydrazide, affording saturated and thus more flexible polymers. All of these polymers were well characterized by spectroscopic means including GPC, UV-Vis, NMR and IR, based on which the tacticity of these polymers was investigated together with nonlinear optical （electric-field-induced second-harmonic generation, EFISH）） analysis.展开更多
Fourier transform infrared spectroscopy (FTIR) has been used to study the effect of tacticityof PMMA on β phase formation of poly vinylidene fluoride (PVF_2) during quenching process.For pure PVF_2, quenching at lowe...Fourier transform infrared spectroscopy (FTIR) has been used to study the effect of tacticityof PMMA on β phase formation of poly vinylidene fluoride (PVF_2) during quenching process.For pure PVF_2, quenching at lower temperature results in the formation of β phase crystallites.The critical quenching temperature for β phase formation is about 30℃. Adding a given amountof PMMA (30%) results in the increase of the critical quenching temperature. For the blends ofPVF_2 with atactic PMMA (a-PMMA), the critical quenching temperature is about 45℃, whilefor the blends with syndiotactic PMMA (s-PMMA), attains to about 70℃.展开更多
With increasingly severe global climate change,a low-carbon economy has become an inevitable trend in the development of the international community.Low-carbon economy is not only related to environmental protection b...With increasingly severe global climate change,a low-carbon economy has become an inevitable trend in the development of the international community.Low-carbon economy is not only related to environmental protection but also has a profound impact on international trade.The purpose of this paper is to explore the impact of a low-carbon economy on the development of international trade and put forward corresponding strategy suggestions.By analyzing the connotation,characteristics,and mechanism of the low-carbon economy on international trade,this paper reveals the important role of the low-carbon economy in promoting the optimization of international trade structure,promoting green technology innovation,and strengthening international cooperation.At the same time,given the challenges brought by a low-carbon economy,this paper puts forward strategies such as strengthening policy guidance,promoting green technology innovation,and improving international trade rules to provide a reference for the sustainable development of international trade[1,2].展开更多
Recent years have witnessed transformative changes brought about by artificial intelligence(AI)techniques with billions of parameters for the realization of high accuracy,proposing high demand for the advanced and AI ...Recent years have witnessed transformative changes brought about by artificial intelligence(AI)techniques with billions of parameters for the realization of high accuracy,proposing high demand for the advanced and AI chip to solve these AI tasks efficiently and powerfully.Rapid progress has been made in the field of advanced chips recently,such as the development of photonic computing,the advancement of the quantum processors,the boost of the biomimetic chips,and so on.Designs tactics of the advanced chips can be conducted with elaborated consideration of materials,algorithms,models,architectures,and so on.Though a few reviews present the development of the chips from their unique aspects,reviews in the view of the latest design for advanced and AI chips are few.Here,the newest development is systematically reviewed in the field of advanced chips.First,background and mechanisms are summarized,and subsequently most important considerations for co-design of the software and hardware are illustrated.Next,strategies are summed up to obtain advanced and AI chips with high excellent performance by taking the important information processing steps into consideration,after which the design thought for the advanced chips in the future is proposed.Finally,some perspectives are put forward.展开更多
Pretended surrender is a kind of traditional stratagem which was commonly seen in the war history of ancient China.As a matter of fact,it is a kind of special psychological tactic,making full use of the enemy’s carel...Pretended surrender is a kind of traditional stratagem which was commonly seen in the war history of ancient China.As a matter of fact,it is a kind of special psychological tactic,making full use of the enemy’s carelessness.In the war culture of ancient China,strategic deception is one of the most important parts.In history,ancient Chinese military strategists developed many kinds of strategic deceptions in the process of the wars.Pretended surrender is one of the most basic ones.Though it looks simple,this stratagem requires the users to have really excellent psychological analysis ability and acting skill so that they can successfully fool their enemy.This stratagem appeared in ancient China in a very early time.With time going by,it developed some new forms,letting the battlefields become more inscrutable.However,this stratagem has its basic logic.After knowing this logic,we can easily see through most of the stratagems of pretended surrender.This stratagem is still of great use in today’s political struggles and commercial warfare.展开更多
Beauty trap is a kind of traditional stratagem originating from ancient times.This stratagem is a type of strategic deception,making full use of human’s desires and weaknesses.No matter whether you are a genius or a ...Beauty trap is a kind of traditional stratagem originating from ancient times.This stratagem is a type of strategic deception,making full use of human’s desires and weaknesses.No matter whether you are a genius or a fool,you will have the opportunity to fall into a trap,especially if the trap is intended for you.Because of this characteristic,beauty trap was usually seen as a kind of effective non-military method,appearing in the war history of many different countries.With time going by,compared with its original form,this stratagem has greatly changed,developing many new forms.Some of them need to be adopted flexibly,combining with different kinds of psychological tactics.Except the field of military,this stratagem can also be seen in political struggles and commercial warfare.After coming to modern society,the beauty trap does not vanish.It seems that this stratagem will accompany the entire process of humanity,simply because the desires of humans will never disappear.展开更多
Feigning madness without becoming insane is a traditional Chinese stratagem recorded in Thirty-Six Stratagems,one of the most famous military works of ancient China.It can be seen in the military history and the polit...Feigning madness without becoming insane is a traditional Chinese stratagem recorded in Thirty-Six Stratagems,one of the most famous military works of ancient China.It can be seen in the military history and the political history of ancient China.It is a high-level psychological tactic,requiring the users to have extremely strong psychological resilience and great insight.Therefore,adopting the stratagem of feigning madness without becoming insane is the game of smart people.In brief,this stratagem is a kind of psychological defense tactic,helping the users protect themselves and gain enough time to prepare for the counterattack.About this stratagem,in ancient Chinese history,there were many successful examples.At the same time,failed cases are also worth studying.As a matter of fact,this traditional stratagem can be adopted in many different fields such as military,politics,and commerce.Thus,the research about this stratagem will be a good reference for the people of modern times.展开更多
The stratagem of the empty city is a kind of traditional stratagem of ancient China.This stratagem is a type of psychological tactic,making full use of the enemy’s caution.It can be simply seen as a sort of deceptive...The stratagem of the empty city is a kind of traditional stratagem of ancient China.This stratagem is a type of psychological tactic,making full use of the enemy’s caution.It can be simply seen as a sort of deceptive tactic,applying to the situations of standoff and retreat.The stratagem of the empty city appeared many times in the war history of ancient China,offering many examples to the researchers.As a matter of fact,in ancient China,it was proved that the stratagem of the empty city could be adopted in many different fields such as military and politics.This stratagem was recorded in Thirty-Six Stratagems,one of the most famous military works of ancient China.With time goes by,compared with its original form,the stratagem of the empty city has greatly changed,developing some new forms.This stratagem is also of great use in modern politics and warfare.展开更多
In recent years,breakthrough has been made in the field of artificial intelligence(AI),which has also revolutionized the industry of robotics.Soft robots featured with high-level safety,less weight,lower power consump...In recent years,breakthrough has been made in the field of artificial intelligence(AI),which has also revolutionized the industry of robotics.Soft robots featured with high-level safety,less weight,lower power consumption have always been one of the research hotspots.Recently,multifunctional sensors for perception of soft robotics have been rapidly developed,while more algorithms and models of machine learning with high accuracy have been optimized and proposed.Designs of soft robots with AI have also been advanced ranging from multimodal sensing,human-machine interaction to effective actuation in robotic systems.Nonethe-less,comprehensive reviews concerning the new developments and strategies for the ingenious design of the soft robotic systems equipped with AI are rare.Here,the new development is systematically reviewed in the field of soft robots with AI.First,background and mechanisms of soft robotic systems are briefed,after which development focused on how to endow the soft robots with AI,including the aspects of feeling,thought and reaction,is illustrated.Next,applications of soft robots with AI are systematically summarized and discussed together with advanced strategies proposed for performance enhancement.Design thoughts for future intelligent soft robotics are pointed out.Finally,some perspectives are put forward.展开更多
The composition of assemblages,diet and behavior of waterbird species with similar ecological features are important aspects in the functioning of aquatic ecosystems.Closely related animal species often share resource...The composition of assemblages,diet and behavior of waterbird species with similar ecological features are important aspects in the functioning of aquatic ecosystems.Closely related animal species often share resources such as space and food in ways that reduce competition,but if the diets of different species strongly overlap,interspecific competition may intensify.This analysis examined behavioral data relating to Great Egret,Little Egret,and Squacco Heron to explore their foraging efficiencies in rich aquatic habitats in an arid zone during post-breeding movements.The fieldwork was carried out in small estuaries of a Wadi on the southern coast of Oman.The frequency of interactions was the highest in Squacco Heron and the lowest in Great Egret.However,the differences in the numbers of inter-and intra-specific interactions between the 3 species were significant.Activity indices calculated for a 5-min period,i.e.,the number of interactions(interaction index)and times of flying and walking(movement index)differed among the 3 species.The number of successful attacks was the highest in Squacco Heron,while the foraging effectiveness of Great Egret and Little Egret was similar.GLM analysis showed that only the movement index was significant,as it had a positive impact on individual foraging success.Great Egret caught more fish than the other 2 heron species which,in turn,caught a greater number of smaller prey items,mostly invertebrates.This study shows that heron species in the same rich habitat employ different foraging tactics.In comparison to the other two heron species,the foraging tactics of Squacco Heron seem to be the most susceptible to competition.However,its greater mobility and using different foraging tactics,enhance its foraging success.展开更多
Harvestmen are a major arachnid order that has experienced a dramatic increase in biological knowledge in the 21st century.The publication of the book Harvestmen:The Biology of Opiliones in 2007 stimulated the develop...Harvestmen are a major arachnid order that has experienced a dramatic increase in biological knowledge in the 21st century.The publication of the book Harvestmen:The Biology of Opiliones in 2007 stimulated the development of many behavioral studies.Although the book is relatively recent,our understanding of the reproductive biology of harvestmen is already outdated due to the fast accumulation of new data.Our goal is to provide an updated review of the subject to serve as a benchmark for the following years.In the pre-copulatory phase,we explore the evolu-tion of facultative parthenogenesis,the factors that may affect the types of mating system,and the role of nuptial gifts in courtship.Regarding the copulatory phase,harvestmen are unique arachnids because they have aflagellate spermatozoa and a penis with complex morphology.We discuss the implications of these two features for sperm competition and cryptic female choice.In the post-copulatory phase,we connect ovi-position site selection and climate conditions to the widespread occurrence of resource defense polygyny,alternative reproductive tactics,and sexual dimorphism in several clades of tropical harvestmen.Finally,we present the different forms of parental care in the order,and discuss the benefits and costs of this behavior,which can be performed either by females or males.Throughout the review,we indicate gaps in our knowl-edge and subjects that deserve further studies.Hopefully,the information synthesized here will stimulate researchers worldwide to embrace harvestmen as a study system and to improve our effort to unravel the mysteries of their reproductive biology.展开更多
During the war between Liao Dynasty(907-1125)and Northern Song Dynasty(960-1127),there was a classic battle that happened in Yanmen Pass(located in today’s Dai County,Xinzhou,Shanxi Province,China).It was a well know...During the war between Liao Dynasty(907-1125)and Northern Song Dynasty(960-1127),there was a classic battle that happened in Yanmen Pass(located in today’s Dai County,Xinzhou,Shanxi Province,China).It was a well known battle of ancient China because a commander of the Song army named Yang Ye(?-986)was really famous in both classical Chinese fictions and Chinese war history.He is the early protagonist of a famous Chinese classic fiction named The Romance of the Yang family’s generals(written in the 16th century,Ming Dynasty of China).The story of his family also appears in other novels.Besides,in history,he was a general who was active in the early stages of the war between Liao Dynasty and Northern Song Dynasty.The battle of Yanmen Pass(980)was one of the most important battles of Yang’s military career.His combat style especially his cavalry tactic can be summarized through researching this battle.展开更多
The legacy of the human misery caused by the application of the herbicides including Agent Purple and Agent Orange contaminated with unknown amounts of dioxin TCDD and Agent Blue, the arsenic-based herbicide, sprayed ...The legacy of the human misery caused by the application of the herbicides including Agent Purple and Agent Orange contaminated with unknown amounts of dioxin TCDD and Agent Blue, the arsenic-based herbicide, sprayed over the jungles, rice fields, and hamlets of Vietnam is still haunting us today. Why did this happen? Could it have been prevented? Was it necessary United States military strategy? Was it an intentional decision to inflict this blight on the enemy soldiers and the Vietnamese, Cambodian, and Laotian civilians, to poison their land and cause generations of harm? Alternatively, was it an unpreventable accident in the march of military history? What patterns in the U.S. government’s thought process could be identified as the cause, which led to the decision to use these herbicides as tactical chemical weapons? If the introduction of herbicide (chemical) weapons had not been made, would the outcome of the Vietnam War and the Secret Wars in Laos and Cambodia have been any different? The objective of this treatise is to outline the role of world events and backgrounds and the role of the leaders, U.S. military, CIA, USDA, U.S. State Department, the U.S. President appointed Ambassadors to Vietnam and Laos, chemical companies, and President Diệm’s Republic of Vietnam (RVN) government and military. Their collective advice led to the decision to use herbicides as military and environmental chemical weapons in the Second Indochina War. Were the National interests achieved by U.S. military strategy in the RVN using herbicide weapons worth the long-term environmental and human health consequences in Vietnam, Cambodia, and Laos? Did it impact the outcome of the Second Indochina War?展开更多
This article mainly analyzes the application of technical and tactical skills in mixed martial arts competitions,including mixed martial arts and its competition characteristics,the main application significance of te...This article mainly analyzes the application of technical and tactical skills in mixed martial arts competitions,including mixed martial arts and its competition characteristics,the main application significance of technical and tactical skills in mixed martial arts competitions,and its primary application strategies.It is hoped that this analysis can provide some guidelines for the appropriate application of mixed martial arts athletes’technical and tactical skills to improve their winning rate in mixed martial arts competitions.展开更多
The conformational and dynamic properties of polypropylene （PP） for both pure melts and blends with different chain tacticity were investigated by Monte Carlo simulation of isotactic （iPP）, atactic （aPP） and syn...The conformational and dynamic properties of polypropylene （PP） for both pure melts and blends with different chain tacticity were investigated by Monte Carlo simulation of isotactic （iPP）, atactic （aPP） and syndiotactic （sPP） polypropylenes. The simulation of coarse-grained PP models was performed on a high coordination lattice incorporating short- and long-range intramolecular interactions from the rotational isomeric state （RIS） model and Lennard-Jones （LJ） potential function of propane pairs, respectively. The dynamics of chains in binary PP/PP mixture were investigated with the composition of C150H302 with different chain taciticity. The diffusion rates of PP with different stereochemistry are generally in the order as： iPP 〉 aPP 〉〉 sPP. For PP/PP blends with 50：50 wt% binary mixtures, immiscibility was observed when sPP was introduced into the mixtures. The diffusion rate of iPP and aPP became slower after mixing, while sPP diffuses significantly faster in the binary mixtures. The mobility of PP chains depends on both intramolecular （molecular size and chain stiffness） and intermolecular （chain packing） interactions. The effect of intramolecular contribution is greater than that of intermolecular contribution for iPP and aPP chains in binary mixtures. For sPP chain, intermolecular interaction has greater influence on the dynamics than intramolecular contribution.展开更多
The unperturbed dimension and temperature character of poly(dibenzyl itaconate)s (PDBzI) are studied by a revised rotational isomeric state (RIS) method. The improved formulas of the mean-square radius of gyration, de...The unperturbed dimension and temperature character of poly(dibenzyl itaconate)s (PDBzI) are studied by a revised rotational isomeric state (RIS) method. The improved formulas of the mean-square radius of gyration, deduced by the pseudo-stereochemical equilibrium approach, may be used to investigate the configurational-conformational properties of atactic polymers with large side groups [poly(itaconates) for instance]. The calculated results showed that poly(itaconates) have larger dimension of the molecule than other vinyl polymers. Comparison of the dimension between considering and without considering side groups showed that the effect of large side groups on the unperturbed dimension for short-chain polymers is more obvious than that of long-chain polymers and, if the dimension of side groups increases, the effect also increases. The dimension differences of PDBzI between short-chain and long-chain polymers are investigated by the relation of characteristic ratios and temperature coefficients with temperature. Moreover, the dependence between the temperature coefficients and the tacticity of chains shows that the temperature characters of the isotactic, syndiotactic and atactic PDBzI chains have remarkable difference.展开更多
文摘Polypropylene(PP) accounts for approximately 28.0% of the global polyolefin market,valued at $243.4 billion in 2022.Known for its lightweight,chemical resistance,costeffectiveness,high strength and melting point,PP is widely used in various applications.Its properties and applications are closely tied to its tacticity.One-dimensional(1D) conventional 13C NMR has been extensively utilized to analyze PP tacticity,but its low sensitivity and longer relaxation time remain drawbacks.Typically,analyzing a single PP sample requires around 9 h of NMR time.Using of a cryogenically cooled 10 mm NMR probe can significantly reduce this measurement time;however,its high cost makes it inaccessible for most NMR laboratories.While the refocused insensitive nuclei enhanced by polarization transfer(RINEPT) technique is well-known for enhancing NMR sensitivity,there are no published studies using 1D 13C RINEPT to quantify PP tacticity.Relaxation agents like chromium(Ⅲ) acetylacetonate(Cr(acac)_(3)) have also been used to reduce relaxation times in polyolefin NMR analyses.Here we introduce a straightforward and easily implementable 1D 13C NMR method for rapid PP tacticity quantification.This method combines Cr(acac)_(3),Bruker's existing RINEPT pulse sequence(ineptrd),and our recently published ~1H decoupling sequence(bi_waltz65_256 pl) to eliminate ~1H decoupling artifacts.It is worth noting that decoupling artifacts are always present.When the signal-to-noise ratio(SNR) is low,these artifacts are obscured by noise.For example,in some two-dimensional(2D) or three-dimensional(3D) NMR spectra,decoupling artifacts are barely visible because of the low SNR.However,when attempting to observe weak signals in ~1D spectra,increasing the sample concentration or the number of scans enhances the SNR,revealing the decoupling artifacts.The decoupling artifacts appeared superimpose with some other weak signals,affecting the measurements of signal intensities.Therefore,improved ~1H-decoupling methods are crucial for such data acquisitio n.This synergy results in a 9.4-to 9.7-fold sensitivity enhancement,equating to an 88-to 94-fold reduction(9.4^(2)≈88,9.7^(2)≈94) in NMR acquisition time compared to conventional 1D 13C NMR experiment with Cr(acac)_3.The time savings are even more substantial compared to experiments without Cr(acac)_3.The faster and quantitative approach is accessible to researchers with or without cryoprobes.Beyond PP,this method can be applied to tacticity measurements of other polyolefins,such as polybutene,polyhexene and polyoctene.
基金This work is supported by the National Natural Science Foundation of China
文摘Propylene was polymerized with a novel supported Ziegler-Natta catalystcontaining 2,2-di-iso-butyl-1,3-dimethoxy-propane (DIBDMP) as internal donor and in theabsence of external donor. The tacticity distribution of polypropylene was obtained by usingtemperature rising elution fractionation (TREF) technique and microstructure of fractionswas studied with ^(13)C-NMR. Compared with the catalyst without electron donor, this cat-alyst gives a considerably narrower tacticity distribution. Fractionation data demonstratethat DIBDMP shows better performance than aromatic diester DNBP (di-n-butyl phtha-late). Chemically inverted propylene units and less stereoblockiness are found in the firstfraction. Possible reasons for these were presented.
基金supported by the National Natural Science Foundation of China(No.20902002)the Introduced Talents from Anhui University of Technology and Science(No.2008YQ009)
文摘After tentative ring-opening cross metathesis （ROCM） of endo-bicyclo[3.2.0]hept-6-en-3-yl 4-bromobenzoate with PhCH = CH2 initiated by （Cy3P）2Cl2Ru = CHPh in CH2Cl2, ring-opening metathesis polymerization （ROMP） of a series of endo-bicyclo[3.2.0]hept-6-en-3-yl benzoates was achieved under the same conditions, furnishing a variety of the corresponding polymers. Then some of them were selected to hydrogenate the C=C double bonds in their backbone with p-tosylhydrazide, affording saturated and thus more flexible polymers. All of these polymers were well characterized by spectroscopic means including GPC, UV-Vis, NMR and IR, based on which the tacticity of these polymers was investigated together with nonlinear optical （electric-field-induced second-harmonic generation, EFISH）） analysis.
文摘Fourier transform infrared spectroscopy (FTIR) has been used to study the effect of tacticityof PMMA on β phase formation of poly vinylidene fluoride (PVF_2) during quenching process.For pure PVF_2, quenching at lower temperature results in the formation of β phase crystallites.The critical quenching temperature for β phase formation is about 30℃. Adding a given amountof PMMA (30%) results in the increase of the critical quenching temperature. For the blends ofPVF_2 with atactic PMMA (a-PMMA), the critical quenching temperature is about 45℃, whilefor the blends with syndiotactic PMMA (s-PMMA), attains to about 70℃.
文摘With increasingly severe global climate change,a low-carbon economy has become an inevitable trend in the development of the international community.Low-carbon economy is not only related to environmental protection but also has a profound impact on international trade.The purpose of this paper is to explore the impact of a low-carbon economy on the development of international trade and put forward corresponding strategy suggestions.By analyzing the connotation,characteristics,and mechanism of the low-carbon economy on international trade,this paper reveals the important role of the low-carbon economy in promoting the optimization of international trade structure,promoting green technology innovation,and strengthening international cooperation.At the same time,given the challenges brought by a low-carbon economy,this paper puts forward strategies such as strengthening policy guidance,promoting green technology innovation,and improving international trade rules to provide a reference for the sustainable development of international trade[1,2].
基金supported by the Hong Kong Polytechnic University(1-WZ1Y,1-W34U,4-YWER).
文摘Recent years have witnessed transformative changes brought about by artificial intelligence(AI)techniques with billions of parameters for the realization of high accuracy,proposing high demand for the advanced and AI chip to solve these AI tasks efficiently and powerfully.Rapid progress has been made in the field of advanced chips recently,such as the development of photonic computing,the advancement of the quantum processors,the boost of the biomimetic chips,and so on.Designs tactics of the advanced chips can be conducted with elaborated consideration of materials,algorithms,models,architectures,and so on.Though a few reviews present the development of the chips from their unique aspects,reviews in the view of the latest design for advanced and AI chips are few.Here,the newest development is systematically reviewed in the field of advanced chips.First,background and mechanisms are summarized,and subsequently most important considerations for co-design of the software and hardware are illustrated.Next,strategies are summed up to obtain advanced and AI chips with high excellent performance by taking the important information processing steps into consideration,after which the design thought for the advanced chips in the future is proposed.Finally,some perspectives are put forward.
文摘Pretended surrender is a kind of traditional stratagem which was commonly seen in the war history of ancient China.As a matter of fact,it is a kind of special psychological tactic,making full use of the enemy’s carelessness.In the war culture of ancient China,strategic deception is one of the most important parts.In history,ancient Chinese military strategists developed many kinds of strategic deceptions in the process of the wars.Pretended surrender is one of the most basic ones.Though it looks simple,this stratagem requires the users to have really excellent psychological analysis ability and acting skill so that they can successfully fool their enemy.This stratagem appeared in ancient China in a very early time.With time going by,it developed some new forms,letting the battlefields become more inscrutable.However,this stratagem has its basic logic.After knowing this logic,we can easily see through most of the stratagems of pretended surrender.This stratagem is still of great use in today’s political struggles and commercial warfare.
文摘Beauty trap is a kind of traditional stratagem originating from ancient times.This stratagem is a type of strategic deception,making full use of human’s desires and weaknesses.No matter whether you are a genius or a fool,you will have the opportunity to fall into a trap,especially if the trap is intended for you.Because of this characteristic,beauty trap was usually seen as a kind of effective non-military method,appearing in the war history of many different countries.With time going by,compared with its original form,this stratagem has greatly changed,developing many new forms.Some of them need to be adopted flexibly,combining with different kinds of psychological tactics.Except the field of military,this stratagem can also be seen in political struggles and commercial warfare.After coming to modern society,the beauty trap does not vanish.It seems that this stratagem will accompany the entire process of humanity,simply because the desires of humans will never disappear.
文摘Feigning madness without becoming insane is a traditional Chinese stratagem recorded in Thirty-Six Stratagems,one of the most famous military works of ancient China.It can be seen in the military history and the political history of ancient China.It is a high-level psychological tactic,requiring the users to have extremely strong psychological resilience and great insight.Therefore,adopting the stratagem of feigning madness without becoming insane is the game of smart people.In brief,this stratagem is a kind of psychological defense tactic,helping the users protect themselves and gain enough time to prepare for the counterattack.About this stratagem,in ancient Chinese history,there were many successful examples.At the same time,failed cases are also worth studying.As a matter of fact,this traditional stratagem can be adopted in many different fields such as military,politics,and commerce.Thus,the research about this stratagem will be a good reference for the people of modern times.
文摘The stratagem of the empty city is a kind of traditional stratagem of ancient China.This stratagem is a type of psychological tactic,making full use of the enemy’s caution.It can be simply seen as a sort of deceptive tactic,applying to the situations of standoff and retreat.The stratagem of the empty city appeared many times in the war history of ancient China,offering many examples to the researchers.As a matter of fact,in ancient China,it was proved that the stratagem of the empty city could be adopted in many different fields such as military and politics.This stratagem was recorded in Thirty-Six Stratagems,one of the most famous military works of ancient China.With time goes by,compared with its original form,the stratagem of the empty city has greatly changed,developing some new forms.This stratagem is also of great use in modern politics and warfare.
基金supported by the Hong Kong Polytechnic University(Project No.1-WZ1Y).
文摘In recent years,breakthrough has been made in the field of artificial intelligence(AI),which has also revolutionized the industry of robotics.Soft robots featured with high-level safety,less weight,lower power consumption have always been one of the research hotspots.Recently,multifunctional sensors for perception of soft robotics have been rapidly developed,while more algorithms and models of machine learning with high accuracy have been optimized and proposed.Designs of soft robots with AI have also been advanced ranging from multimodal sensing,human-machine interaction to effective actuation in robotic systems.Nonethe-less,comprehensive reviews concerning the new developments and strategies for the ingenious design of the soft robotic systems equipped with AI are rare.Here,the new development is systematically reviewed in the field of soft robots with AI.First,background and mechanisms of soft robotic systems are briefed,after which development focused on how to endow the soft robots with AI,including the aspects of feeling,thought and reaction,is illustrated.Next,applications of soft robots with AI are systematically summarized and discussed together with advanced strategies proposed for performance enhancement.Design thoughts for future intelligent soft robotics are pointed out.Finally,some perspectives are put forward.
基金supported by the University of Siedlce,Poland(Theme No.151/23/B and 152/23/B fnanced from a science grant by the Ministry of Education and Science,Poland).
文摘The composition of assemblages,diet and behavior of waterbird species with similar ecological features are important aspects in the functioning of aquatic ecosystems.Closely related animal species often share resources such as space and food in ways that reduce competition,but if the diets of different species strongly overlap,interspecific competition may intensify.This analysis examined behavioral data relating to Great Egret,Little Egret,and Squacco Heron to explore their foraging efficiencies in rich aquatic habitats in an arid zone during post-breeding movements.The fieldwork was carried out in small estuaries of a Wadi on the southern coast of Oman.The frequency of interactions was the highest in Squacco Heron and the lowest in Great Egret.However,the differences in the numbers of inter-and intra-specific interactions between the 3 species were significant.Activity indices calculated for a 5-min period,i.e.,the number of interactions(interaction index)and times of flying and walking(movement index)differed among the 3 species.The number of successful attacks was the highest in Squacco Heron,while the foraging effectiveness of Great Egret and Little Egret was similar.GLM analysis showed that only the movement index was significant,as it had a positive impact on individual foraging success.Great Egret caught more fish than the other 2 heron species which,in turn,caught a greater number of smaller prey items,mostly invertebrates.This study shows that heron species in the same rich habitat employ different foraging tactics.In comparison to the other two heron species,the foraging tactics of Squacco Heron seem to be the most susceptible to competition.However,its greater mobility and using different foraging tactics,enhance its foraging success.
文摘Harvestmen are a major arachnid order that has experienced a dramatic increase in biological knowledge in the 21st century.The publication of the book Harvestmen:The Biology of Opiliones in 2007 stimulated the development of many behavioral studies.Although the book is relatively recent,our understanding of the reproductive biology of harvestmen is already outdated due to the fast accumulation of new data.Our goal is to provide an updated review of the subject to serve as a benchmark for the following years.In the pre-copulatory phase,we explore the evolu-tion of facultative parthenogenesis,the factors that may affect the types of mating system,and the role of nuptial gifts in courtship.Regarding the copulatory phase,harvestmen are unique arachnids because they have aflagellate spermatozoa and a penis with complex morphology.We discuss the implications of these two features for sperm competition and cryptic female choice.In the post-copulatory phase,we connect ovi-position site selection and climate conditions to the widespread occurrence of resource defense polygyny,alternative reproductive tactics,and sexual dimorphism in several clades of tropical harvestmen.Finally,we present the different forms of parental care in the order,and discuss the benefits and costs of this behavior,which can be performed either by females or males.Throughout the review,we indicate gaps in our knowl-edge and subjects that deserve further studies.Hopefully,the information synthesized here will stimulate researchers worldwide to embrace harvestmen as a study system and to improve our effort to unravel the mysteries of their reproductive biology.
文摘During the war between Liao Dynasty(907-1125)and Northern Song Dynasty(960-1127),there was a classic battle that happened in Yanmen Pass(located in today’s Dai County,Xinzhou,Shanxi Province,China).It was a well known battle of ancient China because a commander of the Song army named Yang Ye(?-986)was really famous in both classical Chinese fictions and Chinese war history.He is the early protagonist of a famous Chinese classic fiction named The Romance of the Yang family’s generals(written in the 16th century,Ming Dynasty of China).The story of his family also appears in other novels.Besides,in history,he was a general who was active in the early stages of the war between Liao Dynasty and Northern Song Dynasty.The battle of Yanmen Pass(980)was one of the most important battles of Yang’s military career.His combat style especially his cavalry tactic can be summarized through researching this battle.
文摘The legacy of the human misery caused by the application of the herbicides including Agent Purple and Agent Orange contaminated with unknown amounts of dioxin TCDD and Agent Blue, the arsenic-based herbicide, sprayed over the jungles, rice fields, and hamlets of Vietnam is still haunting us today. Why did this happen? Could it have been prevented? Was it necessary United States military strategy? Was it an intentional decision to inflict this blight on the enemy soldiers and the Vietnamese, Cambodian, and Laotian civilians, to poison their land and cause generations of harm? Alternatively, was it an unpreventable accident in the march of military history? What patterns in the U.S. government’s thought process could be identified as the cause, which led to the decision to use these herbicides as tactical chemical weapons? If the introduction of herbicide (chemical) weapons had not been made, would the outcome of the Vietnam War and the Secret Wars in Laos and Cambodia have been any different? The objective of this treatise is to outline the role of world events and backgrounds and the role of the leaders, U.S. military, CIA, USDA, U.S. State Department, the U.S. President appointed Ambassadors to Vietnam and Laos, chemical companies, and President Diệm’s Republic of Vietnam (RVN) government and military. Their collective advice led to the decision to use herbicides as military and environmental chemical weapons in the Second Indochina War. Were the National interests achieved by U.S. military strategy in the RVN using herbicide weapons worth the long-term environmental and human health consequences in Vietnam, Cambodia, and Laos? Did it impact the outcome of the Second Indochina War?
文摘This article mainly analyzes the application of technical and tactical skills in mixed martial arts competitions,including mixed martial arts and its competition characteristics,the main application significance of technical and tactical skills in mixed martial arts competitions,and its primary application strategies.It is hoped that this analysis can provide some guidelines for the appropriate application of mixed martial arts athletes’technical and tactical skills to improve their winning rate in mixed martial arts competitions.
基金financially supported by the Strategic Scholarships Fellowship Research Network,Commission on Higher Education,Ministry of Education Thailand
文摘The conformational and dynamic properties of polypropylene （PP） for both pure melts and blends with different chain tacticity were investigated by Monte Carlo simulation of isotactic （iPP）, atactic （aPP） and syndiotactic （sPP） polypropylenes. The simulation of coarse-grained PP models was performed on a high coordination lattice incorporating short- and long-range intramolecular interactions from the rotational isomeric state （RIS） model and Lennard-Jones （LJ） potential function of propane pairs, respectively. The dynamics of chains in binary PP/PP mixture were investigated with the composition of C150H302 with different chain taciticity. The diffusion rates of PP with different stereochemistry are generally in the order as： iPP 〉 aPP 〉〉 sPP. For PP/PP blends with 50：50 wt% binary mixtures, immiscibility was observed when sPP was introduced into the mixtures. The diffusion rate of iPP and aPP became slower after mixing, while sPP diffuses significantly faster in the binary mixtures. The mobility of PP chains depends on both intramolecular （molecular size and chain stiffness） and intermolecular （chain packing） interactions. The effect of intramolecular contribution is greater than that of intermolecular contribution for iPP and aPP chains in binary mixtures. For sPP chain, intermolecular interaction has greater influence on the dynamics than intramolecular contribution.
基金Project supported by the National Basic Research Program (973) of China (No. 10574109)the Zhejiang Provincial Science and Technology Department (No. 2005C24008)the Natural Science Foundation of Zhejiang Province (No. Y604064), China
文摘The unperturbed dimension and temperature character of poly(dibenzyl itaconate)s (PDBzI) are studied by a revised rotational isomeric state (RIS) method. The improved formulas of the mean-square radius of gyration, deduced by the pseudo-stereochemical equilibrium approach, may be used to investigate the configurational-conformational properties of atactic polymers with large side groups [poly(itaconates) for instance]. The calculated results showed that poly(itaconates) have larger dimension of the molecule than other vinyl polymers. Comparison of the dimension between considering and without considering side groups showed that the effect of large side groups on the unperturbed dimension for short-chain polymers is more obvious than that of long-chain polymers and, if the dimension of side groups increases, the effect also increases. The dimension differences of PDBzI between short-chain and long-chain polymers are investigated by the relation of characteristic ratios and temperature coefficients with temperature. Moreover, the dependence between the temperature coefficients and the tacticity of chains shows that the temperature characters of the isotactic, syndiotactic and atactic PDBzI chains have remarkable difference.
