Light management holds great promise of realizing high‐performance perovskite solar cells by improving the sunlight absorption with lower recombination current and thus higher power conversion ...efficiency (PCE). Here, a convenient and scalable light trapping scheme is demonstrated by incorporating bioinspired moth‐eye nanostructures into the metal back electrode via soft imprinting technique to enhance the light harvesting in organic–inorganic lead halide perovskite solar cells. Compared to the flat reference cell with a methylammonium lead halide perovskite (CH3NH3PbI3−xClx) absorber, 14.3% of short‐circuit current improvement is achieved for the patterned devices with moth‐eye nanostructures, yielding an increased PCE up to 16.31% without sacrificing the open‐circuit voltage and fill factor. The experimental and theoretical characterizations verify that the cell performance enhancement is mainly ascribed by the broadband polarization‐insensitive light scattering and surface plasmonic effects due to the patterned metal back electrode. It is noteworthy that this light trapping strategy is fully compatible with solution‐processed perovskite solar cells and opens up many opportunities toward the future photovoltaic applications.
A convenient and scalable light trapping scheme is demonstrated to enhance the light harvesting in organic–inorganic lead halide perovskite solar cells, which is realized by incorporating bioinspired moth‐eye nanostructures into the metal back electrode via soft imprinting technique. The efficiency is enhanced to 16.3% due to self‐enhanced absorption by broadband polarization‐insensitive light scattering and surface plasmonic effect.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Energetic benefit and enhanced performance are considered among the most fascinating achievements of collective behaviours, e.g. fish schools and flying formations. The collective locomotion of two ...self-propelled flapping plates initially in a side-by-side arrangement is investigated numerically. Both in-phase and antiphase oscillations for the two plates are considered. It is found that the plates will spontaneously form some stable configurations as a result of the flow-mediated interaction, specifically, the staggered-following (SF) mode and the alternate-leading (AL) mode for the in-phase scenario and the moving abreast (MA) mode and the AL mode for the antiphase scenario. In the SF mode, the rear plate follows the front one with a staggered configuration. In the AL mode, the plates chase each other side-by-side alternately. In terms of propulsive speed and efficiency, the performance of the plates in the SF mode with small lateral spacing
$H$
is found to be better than those in the tandem following case (
$H=0$
) and the side-by-side case (i.e. the AL mode). To achieve higher propulsive efficiency, no matter in-phase or antiphase oscillations, the two plates with moderate bending stiffness, e.g.
$K\approx O(1)$
, are preferred and they should be close enough in the lateral direction. For the side-by-side configuration, the performance of each plate in the antiphase and in-phase scenarios is enhanced and weakened in comparison with that of the isolated plate, respectively. Besides the pressure and vorticity contours, the normal force and thrust acting on the plates are also analysed. It is revealed that the thrust is mainly contributed by the normal force at moderate bending stiffness. The normal force and thrust are critical to the propulsive speed and efficiency. For two self-propelled plates, in view of hydrodynamics, to achieve higher performance the in-phase SF mode and antiphase flappings in the side-by-side configuration are preferred.
Symmetric waterbomb origami Chen, Yan; Feng, Huijuan; Ma, Jiayao ...
Proceedings of the Royal Society. A, Mathematical, physical, and engineering sciences,
06/2016, Volume:
472, Issue:
2190
Journal Article
Peer reviewed
Open access
The traditional waterbomb origami, produced from a pattern consisting of a series of vertices where six creases meet, is one of the most widely used origami patterns. From a rigid origami viewpoint, ...it generally has multiple degrees of freedom, but when the pattern is folded symmetrically, the mobility reduces to one. This paper presents a thorough kinematic investigation on symmetric folding of the waterbomb pattern. It has been found that the pattern can have two folding paths under certain circumstance. Moreover, the pattern can be used to fold thick panels. Not only do the additional constraints imposed to fold the thick panels lead to single degree of freedom folding, but the folding process is also kinematically equivalent to the origami of zero-thickness sheets. The findings pave the way for the pattern being readily used to fold deployable structures ranging from flat roofs to large solar panels.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Photographs of the removal process of motor oil (dyed with Sudan Red I) from water using the rGA.
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To address oil spillage and organic contaminant problems, the preparation of ...efficient sorbent materials is of great importance for global environment and water source protection. Despite extensive studies, sorbents with both high efficiency and recyclability are still desired, particularly with the outstanding sorption performance for different temperature environmental conditions. Herein, we report a robust reduced graphene aerogel (rGA) as an efficient and recyclable sorbent for oils and organic solvents, which shows highly efficient absorption of various oils and organic solvents (up to 19–26 times of its own weight) and excellent recyclability (>5 times) by heat treatment. Moreover, the absorption ability of rGA can be maintained over a wide temperature range of −40°C to 240°C, which can be attributed to the inherent excellent thermal stability of graphene and goodheat dispersal of three dimensional network structure. Based on these excellent properties, the rGA is considered to be an ideal material can be employed for separation and absorption of waste oil and organic contaminants from the water surface at various temperatures.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
With the rapid development of terahertz technologies, basic research and applications of terahertz waves in biomedicine have attracted increasing attention. The rotation and vibrational energy levels ...of biomacromolecules fall in the energy range of terahertz waves; thus, terahertz waves might interact with biomacromolecules. Therefore, terahertz waves have been widely applied to explore features of the terahertz spectrum of biomacromolecules. However, the effects of terahertz waves on biomacromolecules are largely unexplored. Although some progress has been reported, there are still numerous technical barriers to clarifying the relation between terahertz waves and biomacromolecules and to realizing the accurate regulation of biological macromolecules by terahertz waves. Therefore, further investigations should be conducted in the future. In this paper, we reviewed terahertz waves and their biomedical research advantages, applications of terahertz waves on biomacromolecules and the effects of terahertz waves on biomacromolecules. These findings will provide novel ideas and methods for the research and application of terahertz waves in the biomedical field.
Graphene oxide (GO) has been extensively explored in nanomedicine for its excellent physiochemical, electrical, and optical properties. Here, polyethylene glycol (PEG) and polyethylenimine (PEI) are ...covalently conjugated to GO via amide bonds, obtaining a physiologically stable dual‐polymer‐functionalized nano‐GO conjugate (NGO‐PEG‐PEI) with ultra‐small size. Compared with free PEI and the GO‐PEI conjugate without PEGylation, NGO‐PEG‐PEI shows superior gene transfection efficiency without serum interference, as well as reduced cytotoxicity. Utilizing the NIR optical absorbance of NGO, the cellular uptake of NGO‐PEG‐PEI is shown to be enhanced under a low power NIR laser irradiation, owing to the mild photothermal heating that increases the cell membrane permeability without significantly damaging cells. As the results, remarkably enhanced plasmid DNA transfection efficiencies induced by the NIR laser are achieved using NGO‐PEG‐PEI as the light‐responsive gene carrier. More importantly, it is shown that our NGO‐PEG‐PEI is able to deliver small interfering RNA (siRNA) into cells under the control of NIR light, resulting in obvious down‐regulation of the target gene, Polo‐like kinase 1 (Plk1), in the presence of laser irradiation. This study is the first to use photothermally enhanced intracellular trafficking of nanocarriers for light‐controllable gene delivery. This work also encourages further explorations of functionalized nano‐GO as a photocontrollable nanovector for combined photothermal and gene therapies.
PEG and PEI dual‐functionalized ultra‐small graphene oxide (NGO‐PEG‐PEI) with excellent physiologial stability against salts and serum is explored as a gene delivery carrier, which exhibits superior gene transfection efficiency even in the presence of serum, as well as an exciting photothermally controlled gene therapy potential under mild NIR laser irradiation.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Prealloyed Ti-6Al-4V powders were prepared by electrode induction melting gas atomization （EIGA） and plasma rotating electrode process （PREP） in this work. A comparative study of EIGA and PREP ...powders for hot isostatic pressing （HIPing） compaction was conducted. Characterization of important technological parameters such as particle size distribution, powder surface morphology and flowability was carried out. Microstructure and mechanical properties of Ti- 6Al-4V powder compacts HIPed from EIGA and PREP powders were also investigated. The results showed that the EIGA powder has a finer average particle size and higher tap density, while the PREP powder has better flowability and less pores. Micropores can be observed in heat-treated EIGA powder compacts by X-ray tomography and the porosity was found to be about 0.02%. There are no micropores （≥4 μm） to be detected in heat-treated PREP powder compacts. Transgranular fracture mode as well as micropores contributes to the scatter in fatigue property of heat-treated PREP powder compacts. The respective advantages and disadvantages of both EIGA and PREP powders for producing Ti-based complex parts through HIPing were also discussed.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The propulsion of a pitching flexible plate in a uniform flow is investigated numerically. The effects of bending stiffness ($K$), pitching amplitude ($A_L$) and frequency ($St$) on the wake ...patterns, thrust generations and propulsive performances of the fluid–plate system are analysed. Four typical wake patterns, i.e. von Kármán, reversed von Kármán, deflected and chaotic wakes, emerge from various kinematics, and the $St-A_L$ wake maps are given for various $K$. The drag-to-thrust transitions (DTT) and the wake transitions (WT) between the von Kármán and reversed von Kármán wakes are examined. Results indicate that the WT and DTT boundaries can be scaled by the chord-averaged distance of travel, $\mathcal {L}$, which leads to $\mathcal {L}\times St \approx 1$ and $\mathcal {L}\times St \approx 1.2$, respectively. Further, the resonance mechanism for the performance enhancement is revealed and confirmed in a wide range of parameters. The dimensionless average speed of plate, $\mathcal {U^*}\left (=\mathcal {L}\times St\right )$, is adopted merely to characterize the propulsive performances. For the first time, the $\mathcal {U^*}$-based scaling laws for the thrust and power are revealed in pitching rigid and flexible plates for various $A_L$ and $St$. This study may deepen our understanding of biological swimming and flying, and provide a guide for bionic design.
Existing research on transnationalization of labor documents split labor markets between less-skilled (im)migrant workers and native workers in the host countries. But there is little research on how ...labor relations take shape when relatively skilled workers migrate from more developed countries to work temporarily in less-developed countries in the Global South. Based on ethnographic research on a Chinese state-sponsored construction project in Ecuador, this article explicates an understudied case. Although the temporary migrant Chinese workers come from a more developed country and hold higher status jobs, they are compensated at a lower rate and have fewer labor rights compared to their lower status Ecuadorian counterparts. By comparatively examining workers’ everyday interactions and boundary-making practices, this study develops a twofold argument. First, the development strategies and political interests of the home and host states interact to shape divergent recruitment processes and labor policies, which gives rise to disparate working conditions and labor rights between migrant and native workers. Second, the foreign migrant and native workers cope with labor disparities by invoking national stereotypes to draw social boundaries, which exacerbates their labor market splits. This analysis has theoretical implications for understanding labor relations under transnational state capitalism, workers’ strategies against labor control, and the future of labor solidarity in the Global South.
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NUK, OILJ, SAZU, UKNU, UL, UM, UPUK
We report an efficient site-selective synthetic method to C2 and C3 indanyl-substituted indole derivatives via 1,3-dithianyl induced Nazarov-type cyclization. In particular, C2-selective ...indanyl-substituted indoles were directly obtained by a BF 3 ·Et 2 O-promoted sequence of intramolecular C3–C2 migration and Nazarov-type cyclization process.
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