The protection effects of wearing masks against viruses and bacteria have been verified many times over previous pandemics and infectious diseases. However, the supply of the surgical masks can ...barely meet the surging demand at the early stage (first 12 months) of the outbreak of a pandemic. Thus, it is essential to use surgical masks wisely in such urgent times. In this work, we selected two types of surgical masks and systematically explored how actual wearing time influences the protective performances of the masks. Each type of surgical masks was worn for 4, 10, 24, 32 and 48 h, respectively, and the results show that with the increase of actual wearing time, both particulate filtration efficiency (PFE) and bacterial filtration efficiency (BFE) of the masks decline. After wearing for 32 h, the PFEs of both types of masks were still far above the corresponding standard (≥30%, according to YY0469-2011). After wearing for 10 h, the BFEs of both masks were over 95% (which is regarded as the safe value), whereas after 24 and 32 h of wearing, the BFE of one type of mask decreased obviously to 91.6% and 80.0%, respectively. Based on these results, it is rational to conclude that the wearing time of surgical masks should be no more than 10 h.
In this paper, we used cyclic voltammetry method to prepare manganese dioxide with different scanning rates of voltage on a three-dimensional porous nickel foam substrate. We systematically studied ...the influence of the scanning rate of electrodeposition on the morphology, structure, and electrochemical performance of the sample. According to the electrochemical performance, we found the optimal electrodeposition parameters, and the electrode prepared under this condition has a high specific capacitance (458 F g
−1
and 286 F g
−1
at the current density of 1 A g
−1
and 10 A g
−1
) and low impedance.
A new Cd(
) coordination polymers, formulated as Cd(1,4-chdc)(L)
(
) (L = 1-(1
-imidazo4,5-
1,10phenanthrolin-2-yl)naphthalen-2-ol ligands and 1,4-H
chdc = 1,4-cyclohexanedicarboxylate acid), were ...successfully synthesized by using L ligand and 1,4-H
chdc acid under hydrothermal conditions and characterized by single crystal X-ray elemental analyses, diffraction, and IR spectroscopy. Each Cd(
) atom is a distorted pentagonal bipyramidal geometry connecting the deprotonated 1,4-chdc anion to form a 2D layer, and a 2D layer is formed into a 3D supramolecular structure by the π–π stacking interactions between neighboring layers.
The urban residential regeneration strongly supported by the 14th five-year plan of China should achieve social sustainability. Assessing residents' satisfaction with the housing quality and living ...environment is essential for social sustainability and, therefore, should be considered in any transformation process. This study investigates which factors affect residents' satisfaction significantly in high-dense resettlement neighbourhoods, focusing on housing conditions and the community environment. The selected case study is Nanhuan Village, a large resettlement neighbourhood in Suzhou built in the early "80s with medium-density multi-storey buildings and partly transformed with high-density high-rises in 2010. The study analyses residents" satisfaction before and after the regeneration and adopts a mixed research method: in-depth interviews with community managers and designers, fieldwork, and a structured questionnaire survey with residents to determine the influencing factors of satisfaction analysed by a structural equation model. The study identifies 24 indicators and the results highlight what matters for the residents: "community environment", "property management", and "surrounding facilities" are the factors that most significantly impact the residents' satisfaction, even though there are different opinions between the residents of the old part and the regenerated part. The results are surprising: it is not the residential unit that mostly impacts the assessment-once a decent dwelling is provided-but the urban environment. The results also reveal that the densification realized by the transformation is not perceived as a problem. The results of this study can contribute to the definition of the government's urban regeneration policy.
This work used a simple electrochemical reduction method to secondary construct the reduced nickel base (rNi Base) on nickel foam with a nano-core structure. The secondarily constructed base has a ...large specific surface area, which can increase the mass utilization of the active material. The rNi Base was used as a base for the reduction of nickel on Na
+
, K
+
, and
NH
4
+
, respectively. MnO
2
was electrodeposited under three different cation pre-intercalation treatments, and the mechanism of the effect of different monovalent cations to guide the growth of MnO
2
materials was investigated. Finally, rNi/MnO
2
&Na
+
electrode with a special nano cauliflower structure was obtained. The special nanostructure of the electrode enhances its electrochemical performance, possessing 598 F g
− 1
ultra-high specific capacitance at a current density of 1 A g
− 1
and a high specific capacitance of 307.5 F g
− 1
at a high current density of 20 A g
− 1
, and high specific capacitance maintenance rate of 92.7% after 500 cycles of charging and discharging at a current density of 2 A g
− 1
. In addition, the symmetrical supercapacitor assembled with this electrode has a very high specific capacitance (401.1 F g
− 1
at a current density of 1 A g
− 1
) and energy density (80.22Wh kg
− 1
at a power density of 599.99 W kg
− 1
).
Graphical Abstract
A neutral cobalt(ii) compound Cp*Co(1,2-Ph2PC6H4S) (1, Cp* = Me5C5−) catalyzes the radical cyclization of 2-isocyano-biphenyls with alkyl halides, providing a variety of 6-substituted phenanthridines ...and phenanthridine-fused polycyclic compounds in good to excellent yields. The mild reaction conditions allow the catalysis to tolerate various alkyl halides for scaled-up syntheses. Polycyclic compounds with a 6-ethylpropanoate group at the C6 position can be hydrolyzed to provide the 6-ethyl substituted N-heterocycles, which exhibit useful emission properties upon protonation.
The urgency of curbing global warming triggered by growing CO2 emissions has generated significant attention. Direct air capture (DAC) is a crucial and feasible technology to cut CO2 emissions at ...nonpoint sources, therefore achieving negative emissions. Solid porous sorbents have drawn increasing attention for CO2 capture from the atmosphere with ultralow CO2 concentration (ca. 400 ppm). However, most related studies focus on nanoparticle-based adsorbents and their functionalized counterparts, which are more prone to lose weight in the atmosphere. In this context, we summarize nanoparticle composite adsorbents, including zero-dimensional powders, one-dimensional fibers, two-dimensional membranes, and three-dimensional aerogels, and assess the physicochemical properties and typical applications of major types of nanoporous adsorbents in the field of CO2 adsorption and separation with emphasis on DAC. The multidimensions of emerging adsorbents versus CO2 uptake are discussed and compared separately. Combined with recent reported advances, we provide deep insights for the design and synthesis of multifunctional materials for efficient CO2 adsorption. Moreover, life cycle and techno-economic assessments of DAC using different materials are briefly estimated. Finally, challenges and current trends in the DAC system for commercialization have been put forward.
Transparent nanocomposites have attracted considerable attention in many areas including X-ray imaging, wearable electronics, and volumetric display. However, both the transparency and the ...flexibility were largely jeopardized by the loading content of functional nanoparticles (NPs), posing a major challenge to material engineering. Herein, an ultra-high-loading-ceramic nanocomposite film was fabricated by a blade-coating technique. The film exhibited a high transparency over ∼89% in the whole visible region even with a fluoride-ceramic content up to ∼83 wt %. Based on a real-time investigation on the formation process of the film, the refractive-index difference between the nanoparticles and matrix was identified as the dominating factor to transparency. The transmittance spectra based on Rayleigh scattering theory were simulated to screen both nanoparticle radius and loading content, leading to the discovery of a transparency zone for film making. As a proof-of-concept experiment, the transparent film was used as an X-ray scintillation screen, which exhibited a comparable light yield to that of LYSO owing to the mitigated self-absorption effect. The homemade imager demonstrated a spatial resolution of 122 lp/mm, representing a record resolution of 4.1 μm for laboratory X-ray photography. Our work not only provided an experimental procedure to make high-loading functional films but also demonstrated a theoretical model to guide the search for gradients of transparent composites.
Herein, we report a trap-tuning strategy involving alkali metal ions of Li
+
and K
+
, which enabled a fine tuning of afterglow traps at 250 K. Through Li
+
/K
+
doping, a red afterglow from Cs
2
...AgInCl
6
:Mn was activated at room temperature, which was extended up to 3600 s at low temperature. Thermoluminescence measurement revealed a shallow trap at ∼0.50 eV below the conduction band, which could be shifted up- and down-ward by dopant species.
Alkali metal ions were doped in a single-crystal perovskite to tune the trap level, whereby an extended afterglow up to 3600 s was activated at low temperature.
