On September 28th, 2018, a supershear earthquake of moment magnitude (Mw) 7.5 struck the Palu area in central Sulawesi, Indonesia. To gain insight into landslides triggered by the Palu earthquake, a ...detailed landslide interpretation project was carried out in the meizoseismal area. To establish a co-seismic landslide inventory, we collected high-resolution images, including Worldview pre- and post- earthquake images, Sentinel pre- and post- earthquake images and Google Earth pre- and post- earthquake images. The results show that the Palu event triggered at least 7063 co-seismic landslides, including 8 flowslides. The total landslide area is 29.7 km2, with the highest density being 96 landslides/km2. The rock type (Kambuno granite) is a dominant factor influencing the landslide distribution; the average landslide H/L (H is the fall height and L is the horizontal length of an entire landslide) is 0.56. The flowslides that occurred in the Palu Basin are seismic liquefaction-induced landslides that failed along very gentle slopes (generally, slopes that are <3°) and traveled hundreds to thousands of meters, and the average H/L was 0.021.
•The Palu event triggered 7063 landslides, including 8 flowslides•The rock type is a dominant factor influencing landslide distribution•The average mobility indices of landslides and flowslides are 0.56 and 0.021
Most organic polymeric materials have high flammability, for which the large amounts of smoke, toxic gases, heat, and melt drips produced during their burning cause immeasurable damages to human life ...and property every year. Despite some desirable results having been achieved by conventional flame‐retardant methods, their application is encountering more and more difficulties with the ever‐increasing high flame‐retardant requirements such as high flame‐retardant efficiency, great persistence, low release of heat, smoke, and toxic gases, and more importantly not deteriorating or even enhancing the overall properties of polymers. Under such condition, some advanced flame‐retardant methods have been developed in the past years based on “all‐in‐one” intumescence, nanotechnology, in situ reinforcement, intrinsic char formation, plasma treatment, biomimetic coatings, etc., which have provided potential solutions to the dilemma of conventional flame‐retardant methods. This review briefly outlines the development, application, and problems of conventional flame‐retardant methods, including bulk‐additive, bulk‐copolymerization, and surface treatment, and focuses on the raise, development, and potential application of advanced flame‐retardant methods. The future development of flame‐retardant methods is further discussed.
Flame‐retardant methods for polymeric materials are reviewed with particular focus on advanced flame‐retardant methods developed in recent years. Both the advantages and drawbacks of these methods are discussed, and prospects for the future development of flame‐retardant methods are presented. It is hoped that this review will guide the development of flame‐retardant polymeric materials.
Abstract
Although thermal convection is omnipresent in nature and technology and serves important purposes in various energy transport systems, whether convection can be viewed as an independent heat ...transfer means has long been argued The constant coefficient in the original version or convective heat transfer coefficient defined in the modern version of Newton’s cooling law quantifies the ratio of the surface heat flux to the temperature difference between a body surface and an adjacent fluid. However, none of the consistent analytical expressions for these two coefficients are present in Newton’s cooling law. The inherently complex relationship between these pending coefficients and convective heat flux vectors makes revealing the convective mechanism extremely difficult. Theoretical determination of these coefficients would bring new insights to thermal convection and direct applications to thermal management. Here we theoretically show consistent analytical expressions for the constant and convective heat transfer coefficients for various flows to make Newton’s cooling law a complete scientific law. For this purpose, a three-dimensional (3D) energy transfer theory of thermal convection is developed, and the convective heat flux vector, entropy flux vector and entropy generation rate inside the system are derived for both single-phase and phase-change flows. By recasting a control volume system into an equivalent control mass system and employing the first and second laws of thermodynamics, the fundamental advective heat transfer mode characterized by temperature differences and entropy changes is demonstrated. The physical implications underlying the 3D convective formulae are elucidated. Comparisons of the analytical results with laminar experiments and turbulent flow measurement benchmark data validate our theoretical findings. Our 3D heat and entropy transfer theory will broaden the research area of thermal convection processes and open up a new arena for the design and thermal management of convective heat transfer in single-phase and phase-change flows.
Lithium (Li) metal is one of the most promising alternative anode materials of next‐generation high‐energy‐density batteries demanded for advanced energy storage in the coming fourth industrial ...revolution. Nevertheless, disordered Li deposition easily causes short lifespan and safety concerns and thus severely hinders the practical applications of Li metal batteries. Tremendous efforts are devoted to understanding the mechanism for Li deposition, while the final deposition morphology tightly relies on the Li nucleation and early growth. Here, the recent progress in insightful and influential models proposed to understand the process of Li deposition from nucleation to early growth, including the heterogeneous model, surface diffusion model, crystallography model, space charge model, and Li‐SEI model, are highlighted. Inspired by the abovementioned understanding on Li nucleation and early growth, diverse anode‐design strategies, which contribute to better batteries with superior electrochemical performance and dendrite‐free deposition behavior, are also summarized. This work broadens the horizon for practical Li metal batteries and also sheds light on more understanding of other important metal‐based batteries involving the metal deposition process.
Lithium (Li) nucleation and early growth processes significantly determine the final deposition behavior. The recent progress in influential models proposed to understand the process of Li nucleation and early growth is highlighted. Inspired by the abovementioned understanding, diverse anode‐design strategies, which contribute to better batteries with superior electrochemical performance and dendrite‐free deposition behavior, are also summarized.
Abstract
Although many theoretical and experimental studies on convective heat transfer exist, the consistent analytical expression of advection heat flux vector in convection as well as its ...reference temperature in the thermal driving force remains unclear. Here we show theoretically and experimentally the unifying formulae for three-dimensional (3D) heat flux vector of forced and natural convections for compressible laminar flows based on the first law of thermodynamics. It is indicated for a single-phase compressible fluid that advection is no other than heat transfer owing to mass flow in the forms of enthalpy and mechanical energy by gross fluid movement, driven by the temperature difference between the fluid temperature and the potential temperature associated with the relevant adiabatic work done. A simple formula for the total convective heat flux vector of natural convection is also suggested and reformulated in terms of logarithmic density difference as the thermal driving force. The theoretical calculations agree well with the laminar flow experiment results. Our discovery of advection heat transfer for compressible flows caused by the temperature differential in which the potential temperature is regarded as the unifying reference temperature represents a previously unknown thermal driving mechanism. This work would bring fundamental insights into the physical mechanism of convective heat transfer, and opens up new avenue for the design, calculation and thermal management of the 3D convection heat flux problems using the novel thermal driving force for compressible laminar and turbulent flows.
Ultrathin, lightweight, and flexible electromagnetic interference (EMI) shielding materials are urgently demanded to address EM radiation pollution. Efficient design to utilize the shields' ...microstructures is crucial yet remains highly challenging for maximum EMI shielding effectiveness (SE) while minimizing material consumption. Herein, novel cellular membranes are designed based on a facile polydopamine‐assisted metal (copper or silver) deposition on electrospun polymer nanofibers. The membranes can efficiently exploit the high‐conjunction cellular structures of metal and polymer nanofibers, and their interactions for excellent electrical conductivity, mechanical flexibility, and ultrahigh EMI shielding performance. EMI SE reaches more than 53 dB in an ultra‐broadband frequency range at a membrane thickness of merely 2.5 µm and a density of 1.6 g cm−3, and an SE of 44.7 dB is accomplished at the lowest thickness of 1.2 µm. The normalized specific SE is up to 232 860 dB cm2 g−1, significantly surpassing that of other shielding materials ever reported. More, integrated functionalities are discovered in the membrane, such as antibacterial, waterproof properties, excellent air permeability, high resistance to mechanical deformations and low‐voltage uniform heating performance, offering strong potential for applications in aerospace and portable and wearable smart electronics.
A designed scalable, ultrathin, and flexible cellular membrane, composed of high‐conjunction metal‐wrapped polymer nanofibers, exhibits excellent electromagnetic interference shielding performance. Moreover, the membranes effectively integrate multifunctionalities such as antibacterial and waterproof properties, air permeability, and low‐voltage uniform heating performance, offering strong potential for applications in aerospace and portable and wearable smart electronics.
Epstein-Barr virus (EBV) is the first human DNA tumor virus identified from African Burkitt's lymphoma cells. EBV causes ~200,000 various cancers world-wide each year. EBV-associated cancers express ...latent EBV proteins, EBV nuclear antigens (EBNAs), and latent membrane proteins (LMPs). EBNA1 tethers EBV episomes to the chromosome during mitosis to ensure episomes are divided evenly between daughter cells. EBNA2 is the major EBV latency transcription activator. It activates the expression of other EBNAs and LMPs. It also activates MYC through enhancers 400-500 kb upstream to provide proliferation signals. EBNALP co-activates with EBNA2. EBNA3A/C represses CDKN2A to prevent senescence. LMP1 activates NF-κB to prevent apoptosis. The coordinated activity of EBV proteins in the nucleus allows efficient transformation of primary resting B lymphocytes into immortalized lymphoblastoid cell lines in vitro.
We reconstruct the evolution of the dark energy (DE) density using a nonparametric Bayesian approach from a combination of the latest observational data. We caution against parameterizing DE in terms ...of its equation of state as it can be singular in modified gravity models, and using it introduces a bias preventing negative effective DE densities. We find a 3.7 preference for an evolving effective DE density with interesting features. For example, it oscillates around the Λ cold dark matter prediction at z 0.7, and could be negative at z 2.3; DE can be pressure-less at multiple redshifts, and a short period of cosmic deceleration is allowed at 0.1 z 0.2. We perform the reconstruction for several choices of the prior, as well as a evidence-weighted reconstruction. We find that some of the dynamical features, such as the oscillatory behavior of the DE density, are supported by the Bayesian evidence, which is a first detection of a dynamical DE with a positive Bayesian evidence. The evidence-weighted reconstruction prefers a dynamical DE at a (2.5 0.06) significance level.
The Hubble tension and attempts to resolve it by modifying the physics of (or at) recombination motivate finding ways to determine H0 and the sound horizon at the epoch of baryon decoupling rd in ...ways that rely neither on a recombination model nor on late-time Hubble data. In this work, we investigate what one can learn from the current and future BAO data when treating rd and H0 as independent free parameters. It is well known that baryon acoustic oscillations (BAOs) give exquisite constraints on the product rdH0. We show here that imposing a moderate prior on mh2 breaks the degeneracy between rd and H0. Using the latest BAO data, including the recently released the extended Baryon Oscillation Spectroscopic Survey Data Release 16, along with a mh2 prior based on the Planck best-fit Λ cold dark matter (ΛCDM) model, we find rd = 143.7 2.7 Mpc and H0 = 69.6 1.8 km s−1 Mpc−1. BAO data prefers somewhat lower rd and higher H0 than those inferred from Planck data in a ΛCDM model. We find similar values when combing BAO with the Pantheon supernovae, the Dark Energy Survey Year 1 galaxy weak lensing, Planck or SPTPol cosmic microwave background lensing, and the cosmic chronometer data. We perform a forecast for the Dark Energy Spectroscopic Instrument (DESI) and find that, when aided with a moderate prior on mh2, DESI will measure rd and H0 without assuming a recombination model with an accuracy surpassing the current best estimates from Planck.
Abstract
The mismatch between the locally measured expansion rate of the universe and the one inferred from the cosmic microwave background measurements by Planck in the context of the standard ΛCDM, ...known as the Hubble tension, has become one of the most pressing problems in cosmology. A large number of amendments to the ΛCDM model have been proposed in order to solve this tension. Many of them introduce new physics, such as early dark energy, modifications of the standard model neutrino sector, extra radiation, primordial magnetic fields or varying fundamental constants, with the aim of reducing the sound horizon at recombination
r
⋆
. We demonstrate here that any model which only reduces
r
⋆
can never fully resolve the Hubble tension while remaining consistent with other cosmological datasets. We show explicitly that models which achieve a higher Hubble constant with lower values of matter density Ω
m
h
2
run into tension with the observations of baryon acoustic oscillations, while models with larger Ω
m
h
2
develop tension with galaxy weak lensing data.
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