•Reexamine enduring urban green space issues through the lens of COVID-19.•Re-discover the values of accessible urban green space under the influence of COVID-19.•Unique contribution of pocket parks ...in helping to fight the coronavirus.
While the focus of the wide-spread coronavirus is its impacts on people’s lives and economic wellbeing around the world, the pandemic substantially limits people’s available options of physical activities and exacerbates an enduring problem of large urban populations lack accessible green space to fulfill the essential physical and mental health needs. Under the current pandemic situation available green space is further reduced when some parks are closed or open with limited functions to reduce the spread of coronavirus. At the same time, the demand for green space has increased because of the unavailability of other activities. In this essay, we call the attention of urban planners and designers to pocket parks. Studies have shown that the tiny size of pocket parks makes them an easier fit into vacant properties scattered throughout the urban fabric. Therefore, pocket parks can improve health and encourage social cohesion of residents in often underserved high density urban neighborhoods. The potential of pocket parks in providing accessible urban green space to all urban population may have been considered desirable before the coronavirus outbreak and now it should be considered a necessary ‘lifeline’ to improve urban residents’ health during the coronavirus. In addition, with the long-overlooked value of accessible urban green space waken by the global-scale crisis, proper attention and improvement strategy, such as introducing more pocket park could lead to a better future after the COVID-19.
Most studies of structural color in nature concern periodic arrays, which through the interference of light create color. The “color” white however relies on the multiple scattering of light within a ...randomly structured medium, which randomizes the direction and phase of incident light. Opaque white materials therefore must be much thicker than periodic structures. It is known that flying insects create “white” in extremely thin layers. This raises the question, whether evolution has optimized the wing scale morphology for white reflection at a minimum material use. This hypothesis is difficult to prove, since this requires the detailed knowledge of the scattering morphology combined with a suitable theoretical model. Here, a cryoptychographic X‐ray tomography method is employed to obtain a full 3D structural dataset of the network morphology within a white beetle wing scale. By digitally manipulating this 3D representation, this study demonstrates that this morphology indeed provides the highest white retroreflection at the minimum use of material, and hence weight for the organism. Changing any of the network parameters (within the parameter space accessible by biological materials) either increases the weight, increases the thickness, or reduces reflectivity, providing clear evidence for the evolutionary optimization of this morphology.
The brilliant white color of Cyphochilus beetles arises from random scattering of incident light at a disordered network structure made up of chitin. This complex biological network is characterized by cryo X‐ray nanotomography imaging, and this study shows that it is evolutionary optimized for lightness and material use.
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•Eu doping could enhance the SO2 resistance of Mn/TiO2 catalyst for SCR reaction.•The addition of Eu on Mn/TiO2 catalyst inhibited the formation of surface sulfate.•The SCR reaction ...(with SO2) over MnEu/TiO2 catalyst took place through L-H pathway.
Mn/TiO2 catalyst is a promising candidate for future utilization in low-temperature NH3-SCR reaction, but its bad resistance to SO2 is still a great challenge for practical application. In this study, Eu was successfully used as the additive to improve its resistance to SO2 under SCR conditions, while the pretreatment of Mn/TiO2 and MnEu/TiO2 catalyst by SO2 + O2 had a strong deactivation effect on them. In situ DRIFT study clarified that the deactivation of Mn/TiO2-S (SCR + SO2), Mn/TiO2-S (SO2 + O2) and MnEu/TiO2-S (SO2+O2) were mainly originated from the inhibited adsorption of NH3 and NOx species, as well as the formation of a large amount surface sulfate species on them, which had a strong blacking effect on the SCR reactions over the three catalysts via both E-R and L-H routes. After the addition of Eu, SCR reaction over MnEu/TiO2 catalyst with the existence of SO2 took place through L-H pathway, accompanied by the generation of less surface sulfate species, which brought about the excellent SO2 tolerance of MnEu/TiO2 catalyst under SCR conditions.
Low‐melting liquid metal is a hugely promising material for flexible conductive patterns due to its excellent conductivity and supercompliance, especially low‐cost and environmental liquid processing ...technology. However, the ever‐present fluidity characteristic greatly limits the stable shape and reliability of prepared liquid metal conductive electronics. Herein, a novel solidification strategy of liquid GaIn alloys by Ni doping and heat treatment is first reported, which can efficiently create a solid phase in the liquid metal and provide an effective solution for practical applications. Particularly, the liquid characteristic is preserved for conveniently fabricating different flexible electronic circuits, and then the solidification is carried out on prepared conductive patterns by heat treatment. The solidification mechanism is revealed by the interface chemical reaction between Ni and GaIn, creating the solid phase of intermetallic compound (Ga4Ni3 and InNi3) during heat treatment. Moreover, a biphasic GaInNi can be obtained by regulating the atomic ratio of gallium, indium, and nickel. As a result, the obtained GaInNi possesses extremely low sheet resistance (15 ± 4.5 to 135 ± 2.5 mΩ sq−1) and the variation of ΔR/R0 exhibits low level (0–2) when strained up to 100%, which offers a promising strategy to prepare stretchable and reliable liquid metal electronics.
A novel regulation technique for achieving liquid metal phase state is reported in this work, which is a revolutionary promotion of liquid metal engineering applications, successfully transforming an amorphous GaIn alloy into a biphasic state, while simultaneously having high conductivity, stretchability, long‐term stability, and reliable mechanical performance.
To investigate the role of oxygen defects on the photocatalytic activity of TiO2, the TiO2 nanocrystals with/without oxygen defects are successfully synthesized by the hydrothermal and sol-gel ...methods, respectively. The as-prepared TiO2 nanocrystals with defects are light blue and the absorption edge of light is towards the visible light region (∼420 nm). Raman and X-ray photoelectron spectroscopy (XPS) measurements all confirm that the concentration of oxygen vacancies in the TiO2 synthesized by the sol-gel method is less than that synthesized through the hydrothermal route. The introduction of oxygen defects contributes to a new state in the band gap that narrows the band gap, which is the reason for the extension of light absorption into the visible light region. The photocurrent results confirm that this band-gap narrowing enhances the photocurrent response under simulated solar light irradiation. The TiO2 with oxygen defects shows a higher photocatalytic activity for decomposition of a methylene blue solution compared with that of the perfect TiO2 sample. The photocatalytic mechanism is discussed based on the density functional theory calculations and photoluminescence spectroscopy measurements.
TiO2 nanocrystals with/without oxygen defects have been successfully synthesized by the hydrothermal and sol-gel methods, respectively. The obtained TiO2 with defects exhibits an enhanced photocatalytic performance.
Molecular recognition, which is the process of biological macromolecules interacting with each other or various small molecules with a high specificity and affinity to form a specific complex, ...constitutes the basis of all processes in living organisms. Proteins, an important class of biological macromolecules, realize their functions through binding to themselves or other molecules. A detailed understanding of the protein-ligand interactions is therefore central to understanding biology at the molecular level. Moreover, knowledge of the mechanisms responsible for the protein-ligand recognition and binding will also facilitate the discovery, design, and development of drugs. In the present review, first, the physicochemical mechanisms underlying protein-ligand binding, including the binding kinetics, thermodynamic concepts and relationships, and binding driving forces, are introduced and rationalized. Next, three currently existing protein-ligand binding models--the "lock-and-key", "induced fit", and "conformational selection"--are described and their underlying thermodynamic mechanisms are discussed. Finally, the methods available for investigating protein-ligand binding affinity, including experimental and theoretical/computational approaches, are introduced, and their advantages, disadvantages, and challenges are discussed.
Photocatalytic water splitting is a promising method for hydrogen production. Numerous efficient photocatalysts have been synthesized and utilized. However, photocatalysts without a noble metal as ...the co-catalyst have been rarely reported. Herein, a CoP co-catalyst-modified graphitic-C3N4 (g-C3N4/CoP) is investigated for photocatalytic water splitting to produce H2. The g-C3N4/CoP composite is synthesized in two steps. The first step is related to thermal decomposition, and the second step involves an electroless plating technique. The photocatalytic activity for hydrogen evolution reactions of g-C3N4 is distinctly increased by loading the appropriate amount of CoP quantum dots (QDs). Among the as-synthesized samples, the optimized one (g-C3N4/CoP-4%) shows exceptional photocatalytic activity as compared with pristine g-C3N4, generating H2 at a rate of 936 μ mol g−1 h−1, even higher than that of g-C3N4 with 4 wt% Pt (665 μmol g−1 h−1). The UV-visible and optical absorption behavior confirms that g-C3N4 has an absorption edge at 451 nm, but after being composited with CoP, g-C3N4/CoP-4% has an absorption edge at 497 nm. Furthermore, photoluminescence and photocurrent measurements confirm that loading CoP QDs to pristine g-C3N4 not only enhances the charge separation, but also improves the transfer of photogenerated e−-h+ pairs, thus improving the photocatalytic performance of the catalyst to generate H2. This work demonstrates a feasible strategy for the synthesis of highly efficient metal phosphide-loaded g-C3N4 for hydrogen generation.
The photocatalytic activity of H2 generation over g-C3N4/CoP composites prepared by an electroless plating method is much higher than that over pure g-C3N4. The composites boosted the separation and migration of photogenerated carriers, resulting in a higher photocatalytic activity.
To understand the processes of invasions by alien insects is a pre-requisite for improving management. The whitefly Bemisia tabaci is a cryptic species complex that contains some of the most invasive ...pests worldwide. However, extensive field data to show the geographic distribution of the members of this species complex as well as the invasion by some of its members are scarce.
We used field surveys and published data to assess the current diversity and distribution of B. tabaci cryptic species in China and relate the indigenous members to other Asian and Australian members of the complex. The survey covered the 16 provinces where indigenous B. tabaci occur and extends this with published data for the whole of China. We used molecular markers to identify cryptic species. The evolutionary relationships between the different Asian B. tabaci were reconstructed using Bayesian methods. We show that whereas in the past the exotic invader Middle East-Asia Minor 1 was predominant across China, another newer invader Mediterranean is now the dominant species in the Yangtze River Valley and eastern coastal areas, and Middle East-Asia Minor 1 is now predominant only in the south and south eastern coastal areas. Based on mtCO1 we identified four new cryptic species, and in total we have recorded 13 indigenous and two invasive species from China. Diversity was highest in the southern and southeastern provinces and declined to north and west. Only the two invasive species were found in the northern part of the country where they occur primarily in protected cropping. By 2009, indigenous species were mainly found in remote mountainous areas and were mostly absent from extensive agricultural areas.
Invasions by some members of the whitefly B. tabaci species complex can be rapid and widespread, and indigenous species closely related to the invaders are replaced.
•Develop and validated an UPLC-MS/MS method for the identification of ASIV and PAE.•CIM and POG increase AUC0-t and cmax of ASIV and PAE.•Drug-drug interaction happened between Saposhnikoviae Radix, ...Astragali Radix and Paeoniae Radix.•CIM and POG increase AS-IV and PAE exposure via P-glycoprotein and tight junction proteins.
Saposhnikoviae Radix (SR) may enhance the pharmacodynamics of Huangqi Chifeng Tang (HQCFT) in the treatment of cerebral infarction according to our previous research, but the underlying mechanism is unknown. Herein, an in vivo pharmacokinetic assay in rats and in vitro MDCK-MDR1 cell assays were used to investigate the possible mechanism of SR, its main components, and its interactions with Astragali Radix (AR) and Paeoniae Radix (PR). An ultrahigh-performance liquid chromatography–tandem mass spectrometry (UPLC‒MS/MS)-based analytical method for quantifying astragaloside IV (ASIV) and paeoniflorin (PAE) in microdialysis and transport samples was developed. The pharmacokinetic parameters of SR were determined using noncompartmental analyses CCK-8 assays were used to detect the cytotoxicity of ASIV, PAE, cimifugin (CIM), prim-o-glucosylcimifugin (POG) and their combinations. Moreover, drug transport was studied using MDCK-MDR1 cells. Western blotting was performed to measure the protein expression levels of P-GP and MRP1. Claudin-5, ZO-1, and F-actin expression was determined via immunohistochemical staining of MDCK-MDR1 cells. harmacokinetic studies revealed that, compared with those of Huangqi Chifeng Tang-Saposhnikoviae Radix (HQCFT-SR), the Tmax of ASIV increased by 11.11 %, and the MRT0-t and Tmax of PAE increased by 11.19 % and 20 %, respectively, in the HQCFT group. Transport studies revealed that when ASIV was coincubated with 28 μM CIM or POG, the apparent permeability coefficient (Papp) increased by 71.52 % and 50.33 %, respectively. Coincubation of PAE with 120 μM CIM or POG increased the Papp by 87.62 % and 60.95 %, respectively. Moreover, CIM and POG significantly downregulated P-gp and MRP1 (P < 0.05), inhibited the expression of Claudin-5, ZO-1, and F-actin (P < 0.05), and affected intercellular tight junctions (TJs). In conclusion, our study successfully established a selective, sensitive and reproducible UPLC‒MS/MS analytical method to detect drug‒drug interactions between SR, AR and PR in vivo and in vitro, which is beneficial for enhancing the therapeutic efficacies of AR and PR. Moreover, this study provides a theoretical basis for further research on the use of SR as a drug carrier.
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