Amorphous iron phosphate (FePO4) has attracted enormous attention as a promising cathode material for sodium‐ion batteries (SIBs) because of its high theoretical specific capacity and superior ...electrochemical reversibility. Nevertheless, the low rate performance and rapid capacity decline seriously hamper its implementation in SIBs. Herein, we demonstrate a sagacious multi‐step templating approach to skillfully craft amorphous FePO4 yolk–shell nanospheres with mesoporous nanoyolks supported inside the robust porous outer nanoshells. Their unique architecture and large surface area enable these amorphous FePO4 yolk–shell nanospheres to manifest remarkable sodium storage properties with high reversible capacity, outstanding rate performance, and ultralong cycle life.
FePO4 nanospheres consisting of mesoporous nanoyolks supported inside robust porous nanoshells are synthesized by a judicious multi‐step templating strategy using carbon nanospheres as the starting material. Their architecture and composition allow these hierarchical FePO4 yolk–shell nanospheres to manifest excellent sodium storage performance as a cathode material for sodium‐ion batteries.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
This invaluable book is devoted to a rapidly developing area on the research of the qualitative theory of fractional differential equations. It is self-contained and unified in presentation, and ...provides readers the necessary background material required to go further into the subject and explore the rich research literature. The tools used include many classical and modern nonlinear analysis methods such as fixed point theory, measure of noncompactness method, topological degree method, the Picard operators technique, critical point theory and semigroups theory. Based on research work carried out by the author and other experts during the past four years, the contents are very new and comprehensive. It is useful to researchers and graduate students for research, seminars, and advanced graduate courses, in pure and applied mathematics, physics, mechanics, engineering, biology, and related disciplines.
We analyze a brand's disclosure of its supplier list to improve the suppliers’ compliance with social and environmental sustainability standards. We develop a model of a buyer, a supplier, and an ...NGO; when a violation of the supplier occurs, the buyer and the supplier both incur penalties. Given that the disclosure influences the NGO's perception of the supplier and results in a different level of NGO scrutiny, the buyer decides whether to reveal her supplier. Our model characterizes the buyer's optimal revelation strategy and provides the equilibrium efforts of the supplier and the NGO. The results show that an increase in the penalty for the supplier or an increase in the NGO's auditing efficiency always gives the buyer an incentive to reveal the supplier and has a beneficial effect on supply chain sustainability. However, an increase in the penalty for the buyer acts as a deterrent to the revelation, and thus it often has a detrimental effect on sustainability, except when the increase is modest and the buyer makes an individual effort to monitor her supplier. Moreover, although an increase in the NGO's gain in utility from targeting a revealed supplier acts as a deterrent to the revelation, it can have either a beneficial or detrimental effect on sustainability, depending on the extent of the increase and the efficiency of the NGO's auditing. Last, if the buyer can invest in improving the supplier's capability, the above‐mentioned factors that have beneficial (detrimental) impacts on sustainability also make the investment more (less) worthwhile.
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BFBNIB, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
This paper considers a two-echelon supply chain, where a manufacturer sells products through both her own online channel and a traditional retailer. The retailer provides customers with some ...pre-sales services, which have positive impact on the market demand. The manufacturer's online channel free-rides the retailer's pre-sales services by sharing the retailer's sales effort cost. We investigate how free riding affects the two members' pricing/service strategies and profits when the dual channels use the differential and non-differential pricing scenarios, respectively. Additionally, our study presents the following findings. (i) Under the two pricing scenarios, the service-cost sharing contract can effectively stimulate the retailer to improve his service level while free riding occurred. (ii) If the degree of free riding is not very high, the manufacturer would share a larger proportion of service cost and the retailer would set a higher service level in the differential pricing scenario than in the non-differential pricing scenario. (iii) Under the differential pricing scenario, the service-cost sharing contract may avoid price competition between two channels. (iv) The non-differential pricing scenario is more beneficial to the retailer than the differential pricing scenario, but it is just reverse for the manufacturer and whole supply chain.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Traditional coaches need to rely on experience and intuition to adjust athletes’ movements and postures, which has the problems of strong subjectivity and unstable effects. In this paper, an image ...optical processing method based on artificial intelligence is proposed to realize the adaptive adjustment of aerobics athletes. The research uses the image optical processing technology to collect and analyze the movement of athletes in the training process and extract the key movement parameters. Then, combined with artificial intelligence algorithm, the extracted action parameters are analyzed and compared, so as to achieve accurate evaluation and adjustment of athletes’ actions. Finally, the adjustment plan is applied to the training of athletes, and through real-time monitoring and feedback mechanisms, the athletes’ movements and postures are continuously adjusted and optimized. Through experiments and practical applications, the system can accurately determine the movements and postures of athletes, and provide corresponding adjustment plans based on the actual situation. Compared with traditional manual adjustments, the system has higher accuracy and stability, which can effectively improve the technical level and performance ability of athletes.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
C-H functionalization has been emerging as a powerful method to establish carbon-carbon and carbon-heteroatom bonds. Many efforts have been devoted to transition-metal-catalyzed direct ...transformations of C-H bonds. Metal carbenes generated
in situ
from transition-metal compounds and diazo or its equivalents are usually applied as the transient reactive intermediates to furnish a catalytic cycle for new C-C and C-X bond formation. Using this strategy compounds from unactivated simple alkanes to complex molecules can be further functionalized or transformed to multi-functionalized compounds. In this area, transition-metal-catalyzed carbene insertion to C-H bonds has been paid continuous attention. Diverse catalyst design strategies, synthetic methods, and potential applications have been developed. This critical review will summarize the advance in transition-metal-catalyzed carbene insertion to C-H bonds dated up to July 2021, by the categories of C-H bonds from aliphatic C(sp
3
)-H, aryl (aromatic) C(sp
2
)-H, heteroaryl (heteroaromatic) C(sp
2
)-H bonds, alkenyl C(sp
2
)-H, and alkynyl C(sp)-H, as well as asymmetric carbene insertion to C-H bonds, and more coverage will be given to the recent work. Due to the rapid development of the C-H functionalization area, future directions in this topic are also discussed. This review will give the authors an overview of carbene insertion chemistry in C-H functionalization with focus on the catalytic systems and synthetic applications in C-C bond formation.
This review summarizes the recent advance in transition-metal-catalyzed carbene insertion to C-H bonds, forming diverse C-C bonds.
Carbon-sulfur bond cross-coupling has become more and more attractive as an alternative protocol to establish carbon-carbon and carbon-heteroatom bonds. Diverse transformations through ...transition-metal-catalyzed C-S bond activation and cleavage have recently been developed. This review summarizes the advances in transition-metal-catalyzed cross-coupling
via
carbon-sulfur bond activation and cleavage since late 2012 as an update of the critical review on the same topic published in early 2013 (
Chem. Soc. Rev.
, 2013,
42
, 599-621), which is presented by the categories of organosulfur compounds, that is, thioesters, thioethers including heteroaryl, aryl, vinyl, alkyl, and alkynyl sulfides, ketene dithioacetals, sulfoxides including DMSO, sulfones, sulfonyl chlorides, sulfinates, thiocyanates, sulfonium salts, sulfonyl hydrazides, sulfonates, thiophene-based compounds, and C&z.dbd;S functionality-bearing compounds such as thioureas, thioamides, and carbon disulfide, as well as the mechanistic insights. An overview of C-S bond cleavage reactions with stoichiometric transition-metal reagents is briefly given. Theoretical studies on the reactivity of carbon-sulfur bonds by DFT calculations are also discussed.
This review summarizes the advances in transition-metal-catalyzed cross-coupling
via
carbon-sulfur bond activation and cleavage since late 2012 as an update of the critical review published in early 2013 (
Chem. Soc. Rev.
, 2013,
42
, 599-621).
Predicting how belowground carbon storage reflects changes in aboveground vegetation biomass is an unresolved challenge in most ecosystems. This is especially true for fire-prone savannas, where ...frequent fires shape the fraction of carbon allocated to root traits for post-fire vegetation recovery. Here I review evidence on how root traits may respond to frequent fires and propose to leverage root traits to infer belowground carbon dynamics in fire-prone savannas. Evidently, we still lack an understanding of trade-offs in root acquisitive vs. conservative traits in response to frequent fires, nor have we determined which root traits are functionally important to mediate belowground carbon dynamics in a frequently burned environment. Focusing research efforts along these topics should improve our understanding of savanna carbon cycling under future changes in fire regimes.
A
bstract
Positivity bounds are powerful tools to constrain effective field theories. Utilizing the partial wave expansion in the dispersion relation and the full crossing symmetry of the scattering ...amplitude, we derive several sets of generically nonlinear positivity bounds for a generic scalar effective field theory: we refer to these as the
P Q
,
D
su
,
D
stu
and
D
¯
stu
bounds. While the
PQ
bounds and
D
su
bounds only make use of the
s
↔
u
dispersion relation, the
D
stu
and
D
¯
stu
bounds are obtained by further imposing the
s
↔
t
crossing symmetry. In contradistinction to the linear positivity for scalars, these inequalities can be applied to put upper and lower bounds on Wilson coefficients, and are much more constraining as shown in the lowest orders. In particular we are able to exclude theories with soft amplitude behaviour such as weakly broken Galileon theories from admitting a standard UV completion. We also apply these bounds to chiral perturbation theory and we find these bounds are stronger than the previous bounds in constraining its Wilson coefficients.
A
bstract
We develop a formalism to extract triple crossing symmetric positivity bounds for effective field theories with multiple degrees of freedom, by making use of
su
symmetric dispersion ...relations supplemented with positivity of the partial waves,
st
null constraints and the generalized optical theorem. This generalizes the convex cone approach to constrain the
s
2
coefficient space to higher orders. Optimal positive bounds can be extracted by semi-definite programs with a continuous decision variable, compared with linear programs for the case of a single field. As an example, we explicitly compute the positivity constraints on bi-scalar theories, and find all the Wilson coefficients can be constrained in a finite region, including the coefficients with odd powers of
s
, which are absent in the single scalar case.
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