With the depletion of global petroleum and its increasing price, biodiesel has been becoming one of the most promising biofuels for global fuels market. Researchers exploit oleaginous microorganisms ...for biodiesel production due to their short life cycle, less labor required, less affection by venue, and easier to scale up. Many oleaginous microorganisms can accumulate lipids, especially triacylglycerols (TAGs), which are the main materials for biodiesel production. This review is covering the related researches on different oleaginous microorganisms, such as yeast, mold, bacteria and microalgae, which might become the potential oil feedstocks for biodiesel production in the future, showing that biodiesel from oleaginous microorganisms has a great prospect in the development of biomass energy. Microbial oils biosynthesis process includes fatty acid synthesis approach and TAG synthesis approach. In addition, the strategies to increase lipids accumulation via metabolic engineering technology, involving the enhancement of fatty acid synthesis approach, the enhancement of TAG synthesis approach, the regulation of related TAG biosynthesis bypass approaches, the blocking of competing pathways and the multi-gene approach, are discussed in detail. It is suggested that DGAT and ME are the most promising targets for gene transformation, and reducing PEPC activity is observed to be beneficial for lipid production.
Abstract
We take non-Hermitian Aubry–André–Harper models and quasiperiodic Kitaev chains as examples to demonstrate the equivalence and superposition of real and imaginary quasiperiodic potentials ...(QPs) on inducing localization of single-particle states. We prove this equivalence by analytically computing Lyapunov exponents (or inverse of localization lengths) for systems with purely real and purely imaginary QPs. Moreover, when superposed and with the same frequency, real and imaginary QPs are coherent on inducing the localization, in a way which is determined by the relative phase between them. The localization induced by a coherent superposition can be simulated by the Hermitian model with an effective strength of QP, implying that models are in the same universality class. When their frequencies are different and relatively incommensurate, they are incoherent and their superposition leads to less correlation effects. Numerical results show that the localization happens earlier and there is an intermediate mixed phase lacking of mobility edge.
Wave trapping and manipulation are at the heart of modern integrated photonics and acoustics. Grand challenges emerge on increasing the integration density and reducing the wave leakage/noises due to ...fabrication imperfections, especially for waveguides and cavities at subwavelength scales. The rising of robust wave dynamics based on topological mechanisms offers possible solutions. Ideally, in a three-dimensional (3D) topological integrated chip, there are coexisting robust two-dimensional (2D) interfaces, one-dimensional (1D) waveguides and zero-dimensional (0D) cavities. Here, we report the experimental discovery of such a dimensional hierarchy of the topologically-protected 2D surface states, 1D hinge states and 0D corner states in a single 3D system. Such an unprecedented phenomenon is triggered by the higher-order topology in simple-cubic sonic crystals and protected by the space group Formula: see text. Our study opens up a new regime for multidimensional wave trapping and manipulation at subwavelength scales, which may inspire future technology for integrated acoustics and photonics.
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Depression is a widespread psychological disorder that affects up to 20% of the world's population. Traditional Chinese medicine (TCM), with its unique curative effect in depression ...treatment, is gaining increasing attention as the discovery of novel antidepressant drug has become the pursuit of pharmaceutical. This article summarizes the work done on the natural products from TCM that have been reported to conceive antidepressant effects in the past two decades, which can be classified according to various mechanisms including increasing synaptic concentrations of monoamines, alleviating the hypothalamic-pituitary-adrenal (HPA) axis dysfunctions, lightening the impairment of neuroplasticity, fighting towards immune and inflammatory dysregulation. The antidepressant active ingredients identified can be generally divided into saponins, flavonoids, alkaloids, polysaccharides and others. Albiflorin, Baicalein, Berberine chloride, beta-Asarone, cannabidiol, Curcumin, Daidzein, Echinocystic acid (EA), Emodin, Ferulic acid, Gastrodin, Genistein, Ginsenoside Rb1, Ginsenoside Rg1, Ginsenoside Rg3, Hederagenin, Hesperidin, Honokiol, Hyperoside, Icariin, Isoliquiritin, Kaempferol, Liquiritin, L-theanine, Magnolol, Paeoniflorin, Piperine, Proanthocyanidin, Puerarin, Quercetin, Resveratrol (trans), Rosmarinic acid, Saikosaponin A, Senegenin, Tetrahydroxystilbene glucoside and Vanillic acid are Specified in this review. Simultaneously, chemical structures of the active ingredients with antidepressant activities are listed and their sources, models, efficacy and mechanisms are described. Chinese compound prescription and extracts that exert antidepressant effects are also introduced, which may serve as a source of inspiration for further development. In the view of present study, the antidepressant effect of certain TCMs are affirmative and encouraging. However, there are a lot of work needs to be done to evaluate the exact therapeutic effects and mechanisms of those active ingredients, specifically, to establish a unified standard for diagnosis and evaluation of curative effect.
Topological insulators have unconventional gapless edge states where disorder-induced back-scattering is suppressed. In photonics, such edge states lead to unidirectional waveguides which are useful ...for integrated photonic circuitry. Cavity modes, another type of fundamental component in photonic chips, however, are not protected by band topology because of their lower dimensions. Here we demonstrate that concurrent wavevector space and real-space topology, dubbed as dual-topology, can lead to light-trapping in lower dimensions. The resultant photonic-bound state emerges as a Jackiw-Rebbi soliton mode localized on a dislocation in a two-dimensional photonic crystal, as proposed theoretically and discovered experimentally. Such a strongly confined cavity mode is found to be robust against perturbations. Our study unveils a mechanism for topological light-trapping in lower dimensions, which is invaluable for fundamental physics and various applications in photonics.
Most natural and artificial materials have crystalline structures from which abundant topological phases emerge
. However, the bulk-edge correspondence-which has been widely used in experiments to ...determine the band topology from edge properties-is inadequate in discerning various topological crystalline phases
, leading to challenges in the experimental classification of the large family of topological crystalline materials
. It has been theoretically predicted that disclinations-ubiquitous crystallographic defects-can provide an effective probe of crystalline topology beyond edges
, but this has not yet been confirmed in experiments. Here we report an experimental demonstration of bulk-disclination correspondence, which manifests as fractional spectral charge and robust bound states at the disclinations. The fractional disclination charge originates from the symmetry-protected bulk charge patterns-a fundamental property of many topological crystalline insulators (TCIs). Furthermore, the robust bound states at disclinations emerge as a secondary, but directly observable, property of TCIs. Using reconfigurable photonic crystals as photonic TCIs with higher-order topology, we observe these hallmark features via pump-probe and near-field detection measurements. It is shown that both the fractional charge and the localized states emerge at the disclination in the TCI phase but vanish in the trivial phase. This experimental demonstration of bulk-disclination correspondence reveals a fundamental phenomenon and a paradigm for exploring topological materials.
We demonstrate experimentally that a photonic crystal made of Al_{2}O_{3} cylinders exhibits topological time-reversal symmetric electromagnetic propagation, similar to the quantum spin Hall effect ...in electronic systems. A pseudospin degree of freedom in the electromagnetic system representing different states of orbital angular momentum arises due to a deformation of the photonic crystal from the ideal honeycomb lattice. It serves as the photonic analogue to the electronic Kramers pair. We visualized qualitatively and measured quantitatively that microwaves of a specific pseudospin propagate only in one direction along the interface between a topological photonic crystal and a trivial one. As only a conventional dielectric material is used and only local real-space manipulations are required, our scheme can be extended to visible light to inspire many future applications in the field of photonics and beyond.
Gallium‐based metallic liquids, exhibiting high theoretical capacity, are considered a promising anode material for room‐temperature liquid metal alkali‐ion batteries. However, electrochemical ...performances, especially the cyclic stability, of the liquid metal anode for alkali‐ion batteries are strongly limited because of the volume expansion and unstable solid electrolyte interphase film of liquid metal. Here, the bottleneck problem is resolved by designing carbon encapsulation on gallium–indium liquid metal nanoparticles (EGaIn@C LMNPs). A superior cycling stability (644 mAh g−1 after 800 cycles at 1.0 A g−1) is demonstrated for lithium‐ion batteries, and excellent cycle stability (87 mAh g−1 after 2500 cycles at 1.0 A g−1) is achieved for sodium‐ion batteries by carbon encapsulation of the liquid metal anode. Morphological and phase changes of EGaIn@C LMNPs during the electrochemical reaction process are revealed by in situ transmission electron microscopy measurements in real‐time. The origin for the excellent performance is uncovered, that is the EGaIn@C core–shell structure effectively suppresses the non‐uniform volume expansion of LMNPs from ≈160% to 127%, improves the electrical conductivity of the LMNPs, and exhibits superior electrochemical kinetics and a self‐healing phenomenon. This work paves the way for the applications of room‐temperature liquid metal anodes for high‐performance alkali‐ion batteries.
Morphological and phase changes of gallium–indium liquid metal nanoparticles (EGaIn@C LMNPs) during the electrochemical reaction process are revealed by in situ TEM measurements in real‐time. The presence of the carbon shell effectively inhibits the volume expansion of the LMNPs during lithiation, and the EGaIn@C LMNPs as a whole can be recovered to their initial state after the discharge–charge cycle.
Higher-order topology yields intriguing multidimensional topological phenomena, while Weyl semimetals have unconventional properties such as chiral anomaly. However, so far, Weyl physics remain ...disconnected with higher-order topology. Here, we report the theoretical discovery of higher-order Weyl semimetals and thereby the establishment of such an important connection. We demonstrate that higher-order Weyl semimetals can emerge in chiral materials such as chiral tetragonal crystals as the intermediate phase between the conventional Weyl semimetal and 3D higher-order topological phases. Higher-order Weyl semimetals manifest themselves uniquely by exhibiting concurrent chiral Fermi-arc surface states, topological hinge states, and the momentum-dependent fractional hinge charge, revealing a novel class of higher-order topological phases.
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