Biological systems organize multiple hierarchical structures in parallel, and create dynamic assemblies and functions by energy dissipation. In contrast, emerging artificial non-equilibrium ...self-assembling systems have remained relatively simplistic concerning hierarchical design, and non-equilibrium multi-component systems are uncharted territory. Here we report a modular DNA toolbox allowing to program transient non-equilibrium multicomponent systems across hierarchical length scales by introducing chemically fueled molecular recognition orchestrated by reaction networks of concurrent ATP-powered ligation and cleavage of freely programmable DNA building blocks. Going across hierarchical levels, we demonstrate transient side-chain functionalized nucleic acid polymers, and further introduce the concept of transient cooperative multivalency as a key to bridge length scales to pioneer fuel-driven encapsulation, self-assembly of colloids, and non-equilibrium transient narcissistic colloidal self-sorting on a systems level. The fully programmable and functionalizable DNA components pave the way to design chemically fueled 4D (3 space, 1 time) molecular multicomponent systems and autonomous materials.
With the change of social economic system and the rapid growth of agricultural economy in China, the amount of agricultural energy consumption and carbon dioxide emissions has increased dramatically. ...Based on the estimation of agricultural carbon dioxide emissions from 1991 to 2018 in China, this paper uses EKC model to analyze economic growth and agricultural carbon dioxide emissions. The Kaya method is used to decompose the factors affecting agricultural carbon dioxide emissions. The experimental results show that there is a co-integration relationship between economic growth and the total intensity of agricultural carbon emissions, and between economic growth and the intensity of carbon emissions caused by five types of carbon sources: fertilizer, pesticide, agricultural film, agricultural diesel oil and tillage. Economic growth is the main driving factor of agricultural carbon dioxide emissions. In addition, technological progress has a strong role in promoting carbon emission reduction, but it has a certain randomness. However, the impact of energy consumption structure and population size on carbon emissions is not obvious.
This paper presents a circuit-compatible compact model for the intrinsic channel region of the MOSFET-like single-walled carbon-nanotube field-effect transistors (CNFETs). This model is valid for ...CNFET with a wide range of chiralities and diameters and for CNFET with either metallic or semiconducting carbon-nanotube (CNT) conducting channel. The modeled nonidealities include the quantum confinement effects on both circumferential and axial directions, the acoustical/optical phonon scattering in the channel region, and the screening effect by the parallel CNTs for CNFET with multiple CNTs. In order to be compatible with both large-(digital) and small-signal (analog) applications, a complete transcapacitance network is implemented to deliver the real-time dynamic response. This model is implemented with an HSPICE. Using this model, we project a 13 times CV/I improvement of the intrinsic CNFET with (19, 0) CNT over the bulk n-type MOSFET at the 32-nm node. The model described in this paper serves as a starting point toward the complete CNFET-device model incorporating the additional device/circuit-level non-idealities and multiple CNTs reported in the paper of Deng and Wong.
This paper presents a complete circuit-compatible compact model for single-walled carbon-nanotube field-effect transistors (CNFETs) as an extension to Part 1 of this two-part paper. For the first ...time, a universal circuit-compatible CNFET model including the practical device nonidealities is implemented with HSPICE. In addition to the nonidealities included in the companion paper, this paper includes the elastic scattering in the channel region, the resistive source/drain (S/D), the Schottky-barrier resistance, and the parasitic gate capacitances. More than one nanotube per device can be modeled. Compared to silicon technology, the CNFETs show much better device performance based on the intrinsic gate-delay metric (six times for nFET and 14 times for pFET) than the MOSFET device at the 32-nm node, even with device nonidealities. This large speed improvement is significantly degraded (by a factor of five to eight) by interconnect capacitance in a real circuit environment. We performed circuit-performance comparison with all the standard digital library cells between CMOS random logic and CNFET random logic with HSPICE simulation. Compared to CMOS circuits, the CNFET circuits with one to ten carbon nanotubes per device is about two to ten times faster, the energy consumption per cycle is about seven to two times lower, and the energy-delay product is about 15-20 times lower, considering the realistic layout pattern and the interconnect wiring capacitance.
SUMMARY
Carotenoids are important natural pigments that give bright colors to plants. The difference in the accumulation of carotenoids is one of the key factors in the formation of various colors in ...carrot taproots. Carotenoid cleavage dioxygenases (CCDs), including CCD and 9‐cis epoxycarotenoid dioxygenase, are the main enzymes involved in the cleavage of carotenoids in plants. Seven CCD genes have been annotated from the carrot genome. In this study, through expression analysis, we found that the expression level of DcCCD4 was significantly higher in the taproot of white carrot (low carotenoid content) than orange carrot (high carotenoid content). The overexpression of DcCCD4 in orange carrots caused the taproot color to be pale yellow, and the contents of α‐ and β‐carotene decreased sharply. Mutant carrot with loss of DcCCD4 function exhibited yellow color (the taproot of the control carrot was white). The accumulation of β‐carotene was also detected in taproot. Functional analysis of the DcCCD4 enzyme in vitro showed that it was able to cleave α‐ and β‐carotene at the 9, 10 (9′, 10′) double bonds. In addition, the number of colored chromoplasts in the taproot cells of transgenic carrots overexpressing DcCCD4 was significantly reduced compared with that in normal orange carrots. Results showed that DcCCD4 affects the accumulation of carotenoids through cleavage of α‐ and β‐carotene in carrot taproot.
Significance Statement
We analyzed seven carotenoid cleavage dioxygenase genes annotated from the carrot genome. Functional analysis revealed that DcCCD4 catalyzes the degradation of α‐ and β‐carotene to affect carotenoid accumulation. This work may provide a reference for generating new plant varieties with ideal color.
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Hundreds of piezoelectric ultrasonic motors (PUSMs) have been proposed for scientific researches and developed for commercial applications in the past decade. They are surveyed and ...mainly classified into three types: standing wave motor (SWM), traveling wave motor (TWM) and hybrid modes motor (HMM), according to their operating principles. These different types of PUSMs are discussed in detail, in terms of their operating principles, structures, features and performances. The methods to realize the multi-degree-of-freedom (multi-DOF) motions of the PUSMs are also investigated based on the basic operating principles of the SWM, TWM and HMM. Some practical applications and representative designs of the PUSMs are introduced briefly. Finally, further efforts and research perspectives of the PUSM are summarized. This review contributes to a comprehensive understanding of the state of arts of the PUSM.
Thermal conductivity plays a pivotal role in understanding the dynamics and evolution of Earth's interior. The Earth's lower mantle is dominated by MgSiO3 polymorphs which may incorporate trace ...amounts of water. However, the thermal conductivity of MgSiO3‐H2O binary system remains poorly understood. Here, we calculate the thermal conductivity of water‐free and water‐bearing bridgmanite, post‐perovskite, and MgSiO3 melt, using a combination of Green‐Kubo method with molecular dynamics simulations based on a machine learning potential of ab initio quality. The thermal conductivities of water‐free bridgmanite and post‐perovskite overall agree well with previous theoretical and experimental studies. The presence of water mildly reduces the thermal conductivity of the host minerals, significantly weakens the temperature dependence of the thermal conductivity, and reduces the thermal anisotropy of post‐perovskite. Overall, water reduces the thermal conductivity difference between bridgmanite and post‐perovskite, and thus may attenuate lateral heterogeneities of the core‐mantle boundary heat flux.
Plain Language Summary
MgSiO3 is a major component of the Earth and water may dissolve into it. Even a small amount of water may affect the thermal conductivity of minerals and influence the heat transport in the Earth's interior, which is essential for the dynamics and evolution of our planet. However, the effect of water on the thermal conductivity of MgSiO3 remains largely unknown. In this study, we use computer simulations based on machine learning methods to investigate the thermal conductivity of MgSiO3‐H2O system. We find that adding water reduces the thermal conductivity of MgSiO3 mineral, makes the thermal conductivity less dependent on temperature, and also diminishes the differences in heat conduction in various directions. Our results suggest that the presence of water may reduce the increase in heat flow that is expected when MgSiO3 changes its structure at extreme depths and exerts influences on geological processes in the deep mantle.
Key Points
Thermal conductivity of MgSiO3‐H2O system is calculated using Green‐Kubo method with machine learning potentials
Water weakens the temperature dependence and the anisotropy of thermal conductivity of minerals
Water reduces the thermal conductivity enhancement effect due to the phase transition from bridgmanite to post‐perovskite
Acoustic black holes (ABHs) in plates have shown great potential in a variety of applications that range from passive noise and vibration reduction, to energy harvesting thanks to localization, or to ...unusual flexural wave manipulation like lensing, or negative refraction and bi-refraction. The ABH effect can be typically achieved in plates by embedding regular arrays of circular cuneate indentations, with power-law profile. In this paper, we suggest new ring-shaped ABH designs that may be used for vibration isolation. Many common situations in the vibroacoustics of built-up structures involve wave propagation in plates excited at a small source area. This could be the case, for instance, of a beam/plate connection. It is herein proposed to surround the plate excitation region by means of ring-shaped ABHs to prevent the transmission of vibrations outside them. Several configurations of ABHs are tested, from concentric annular ABHs in different number and sizes to traditional circular ABHs in a ring arrangement. The inclusion of stiffeners to prevent excessive structural plate weakness due to the ABH indentations is also addressed. The performance of the ABH designs are analyzed by means of a semi-analytical approach that uses two-dimensional Gaussian functions to approximate the plate flexural displacement field, in the framework of the Rayleigh-Ritz method. The annular ABHs are shown to exhibit remarkable good isolation for the whole frequency range. An explanation is provided for their behavior.
Sarcopenia is a progressive and widespread skeletal muscle disease that is related to an increased possibility of adverse consequences such as falls, fractures, physical disabilities and death, and ...its risk increases with age. With the deepening of the understanding of sarcopenia, the disease has become a major clinical disease of the elderly and a key challenge of healthy ageing. However, the exact molecular mechanism of this disease is still unclear, and the selection of treatment strategies and the evaluation of its effect are not the same. Most importantly, the early symptoms of this disease are not obvious and are easy to ignore. In addition, the clinical manifestations of each patient are not exactly the same, which makes it difficult to effectively study the progression of sarcopenia. Therefore, it is necessary to develop and use animal models to understand the pathophysiology of sarcopenia and develop therapeutic strategies. This paper reviews the mouse models that can be used in the study of sarcopenia, including ageing models, genetically engineered models, hindlimb suspension models, chemical induction models, denervation models, and immobilization models; analyses their advantages and disadvantages and application scope; and finally summarizes the evaluation of sarcopenia in mouse models.
A recent Research Article in this journal by Matito and co‐workers claimed that none of the oxidation states of a butadiyne‐linked six‐porphyrin nanoring exhibit global aromaticity or ...antiaromaticity. Here we show that this conclusion is incorrect. Experimental data from NMR spectroscopy for a whole family of nanorings provide strong evidence for global ring currents. The NMR data reveal these ring currents directly, without needing analysis by density functional theory (DFT). Furthermore, DFT calculations reproduce the experimental results when a suitable functional is used.
Porphyrin nanoring template complexes provide a wealth of experimental NMR spectroscopy data, which are sensitive to global ring currents and which can be used to answer this question. Both experiment and theory confirm that nanoring cations are globally (anti)aromatic based on magnetic shielding evidence, and consistent with Hückel's rule.
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