Organic‐inorganic hybrid halide perovskites show a unique two‐channel thermal transport through propagons and diffusons, largely affecting other energy carriers for opto‐ and thermoelectric ...applications. Taking CH3NH3PbI3 as a prototype, the impact of iodine vacancy point defects on the two‐channel thermal transport is investigated using theoretical calculations and experimental validations. This work finds that iodine vacancies suppress the thermal transport in the propagon channel significantly, but less in the diffuson channel. This results in a weaker reduction of the total thermal conductivity (TC) than that predicted by the classical Klemens model. The TC reduction in the diffuson channel is mainly attributed to the declined vibrational density of states. Moreover, low‐frequency diffusons transformed from propagons compensate the reduction of TC in the diffuson channel, resulting in a dominant contribution from the diffuson channel to the total TC, which is 55% to 85% for 0% to 6% vacancy concentration. CH3NH3PbI3 also shows ultra‐defect‐tolerant diffusonic thermal transport, ≈1–2 orders of magnitude lower than diamond in the defect sensitivity factor. This work shows both scientific insights into the new two‐channel thermal transport mechanism in complex material systems with disorder, and technological significance on halide perovskites for solar cell, light‐emitting diode, thermoelectric, and memristor applications.
Unique two‐channel thermal transport in MAPbI3 is studied using theories and experiments. Disordered lattice and vacancy defects suppress the thermal transport in propagon channel, but less in diffuson channel. Low‐frequency diffusons transform from propagons as vacancies increase, resulting in dominant diffuson contribution of ≈55%–85% to total thermal conductivity. Ultra defect‐tolerant diffusonic thermal transport is observed in MAPbI3.
Much progress has been made toward deciphering RHO GTPase functions, and many studies have convincingly demonstrated that altered signal transduction through RHO GTPases is a recurring theme in the ...progression of human malignancies. It seems that 20 canonical RHO GTPases are likely regulated by three GDIs, 85 GEFs, and 66 GAPs, and eventually interact with >70 downstream effectors. A recurring theme is the challenge in understanding the molecular determinants of the specificity of these four classes of interacting proteins that, irrespective of their functions, bind to common sites on the surface of RHO GTPases. Identified and structurally verified hotspots as functional determinants specific to RHO GTPase regulation by GDIs, GEFs, and GAPs as well as signaling through effectors are presented, and challenges and future perspectives are discussed.
Interleukin‐6 (IL‐6) is critically involved in liver regeneration after partial hepatectomy (PHX). Previous reports suggest that IL‐6 trans‐signaling through the soluble IL‐6/IL‐6R complex is ...involved in this process. However, the long‐term contribution of IL‐6 trans‐signaling for liver regeneration after PHX is unknown. PHX‐induced generation of the soluble IL‐6R by ADAM (a disintegrin and metallo) proteases enables IL‐6 trans‐signaling, in which IL‐6 forms an agonistic complex with the soluble IL‐6 receptor (sIL‐6R) to activate all cells expressing the signal‐transducing receptor chain glycoprotein 130 (gp130). In contrast, without activation of ADAM proteases, IL‐6 in complex with membrane‐bound IL‐6R and gp130 activates classic signaling. Here, we describe the generation of IL‐6 trans‐signaling mice, which exhibit boosted IL‐6 trans‐signaling and abrogated classic signaling by genetic conversion of all membrane‐bound IL‐6R into sIL‐6R proteins phenocopying hyperactivation of ADAM‐mediated shedding of IL‐6R as single substrate. Importantly, although IL‐6R deficient mice were strongly affected by PHX, survival and regeneration of IL‐6 trans‐signaling mice was indistinguishable from control mice, demonstrating that IL‐6 trans‐signaling fully compensates for disabled classic signaling in liver regeneration after PHX. Moreover, we monitored the long‐term consequences of global IL‐6 signaling inhibition versus IL‐6 trans‐signaling selective blockade after PHX by IL‐6 monoclonal antibodies and soluble glycoprotein 130 as fragment crystallizable fusion, respectively. Both global IL‐6 blockade and selective inhibition of IL‐6 trans‐signaling results in a strong decrease of overall survival after PHX, accompanied by decreased signal transducer and activator of transcription 3 phosphorylation and proliferation of hepatocytes. Mechanistically, IL‐6 trans‐signaling induces hepatocyte growth factor production by hepatic stellate cells. Conclusion: IL‐6 trans‐signaling, but not classic signaling, controls liver regeneration following PHX.
Solar vapor generation is considered a green and practical approach to take advantage of solar energy as a renewable source and provide pure water. However, developing suitable materials with high ...efficiency and long-term stability under one sun illumination is challenging. Consequently, in this paper, we manifested two-dimensional Zn/Co zeolitic imidazolate framework (ZIF)-L as a sacrificial template to prepare carbon nanotube (CNT) through carbonization of the ZIF-L (Z-CNT). This porous Z-CNT as the solar absorber was deposited on a low-cost fiber paper, as a carrier for water transport by the capillary effect. A polystyrene foam was placed under the provided film, which prevents the heat loss to bulk water. By utilizing this solar vapor generator, a high water evaporation rate of 1.44 kg m
2
h
−1
and a photothermal conversion efficiency of 84% was achieved under one sun. Beside the porosity, high light adsorption of carbon nano tubes (CNT) due to having black colour and low thermal conductivity of this material incorporate the high achieved efficiency.
Perovskite solar cells (PSCs) are currently under vigorous research and development, owing to their compelling power conversion efficiencies. PSCs are solution-processed and, therefore, are ...fabricated using casting and printing methods, such as spin, spray and blade coating. The coating characteristics significantly depend on the physical and rheological properties of the solutions. Thus, due to the scarcity of such properties, in this work, we report the surface tension, viscosity, density, and contact angle of selected methylammonium lead halide perovskite solutions, in order to gain insight into the behavior of the perovskite solutions and the range of such physical properties. The contact angles were measured on PEDOT:PSS and compact TiO2 (c-TiO2) substrates, commonly used as the underneath layers of the perovskite film. In total, 12 solutions of CH3NH3PbI3 and CH3NH3PbI3-xClx dissolved in common solvents, as well as solutions of PbI2, PbCl2, and CH3NH3I were tested. Among the results, it is shown that the tested perovskite solutions are Newtonian, the apparent contact angles on the mesoporous TiO2 (m-TiO2) are close to zero, on the PEDOT:PSS are around 10°, and on the c-TiO2 are around 30°. Also, contact angle hysteresis is observed in the case of the c-TiO2 substrates. Representative impact dynamics and spreading of perovskite solution droplets are also studied, to demonstrate the importance of the solution properties and process parameters on the coating process.
The Tre2-Bub2-Cdc16 (TBC) domain-containing RAB-specific GTPase-activating proteins (TBC/RABGAPs) are characterized by the presence of highly conserved TBC domains and act as negative regulators of ...RABs. The importance of TBC/RABGAPs in the regulation of specific intracellular trafficking routes is now emerging, as is their role in different diseases. Importantly, TBC/RABGAPs act as key regulatory nodes, integrating signalling between RABs and other small GTPases and ensuring the appropriate retrieval, transport and delivery of different intracellular vesicles.
Marine renewable energy, including tidal renewable energy, is one of the less exploited sources of energy that could contribute to energy demand, while reducing greenhouse gas emissions. Amongst ...several proposals to build tidal range structure (TRS), a tidal lagoon has been proposed for construction in Swansea Bay, in the South West of the UK, but this scheme was recently rejected by the UK government due to the high electricity costs. This decision makes the optimisation of such schemes more important for the future. This study proposes various novel approaches by breaking the operation into small components to optimise the operation of TRS using a widely used 0-D modelling methodology. The approach results in a minimum 10% increase in energy output, without the inclusion of pumping, in comparison to the maximum energy output using a similar operation for all tides. This increase in energy will be approximately 25% more when pumping is included. The optimised operation schemes are used to simulate the lagoon operation using a 2-D model and the differences between the results are highlighted.
In this “nano idea” paper, three concepts for the preparation of methylammonium lead halide perovskite particles are proposed, discussed, and tested. The first idea is based on the wet chemistry ...preparation of the perovskite particles, through the addition of the perovskite precursor solution to an anti-solvent to facilitate the precipitation of the perovskite particles in the solution. The second idea is based on the milling of a blend of the perovskite precursors in the dry form, in order to allow for the conversion of the precursors to the perovskite particles. The third idea is based on the atomization of the perovskite solution by a spray nozzle, introducing the spray droplets into a hot wall reactor, so as to prepare perovskite particles, using the droplet-to-particle spray approach (spray pyrolysis). Preliminary results show that the spray technology is the most successful method for the preparation of impurity-free perovskite particles and perovskite paste to deposit perovskite thin films. As a proof of concept, a perovskite solar cell with the paste prepared by the sprayed perovskite powder was successfully fabricated.
Display omitted
•Heavy monovalent and trivalent doping achieved in single crystals of MAPbI3 and MAPbBr3.•Monovalent doping forms microstrains and enhances electrical conductivity by 10 ∼ 100 ...times.•Trivalent doping with Bi3+ and Sb3+ significantly enhances electrical conductivity by 105.•Bi3+ doping oxidizes the deep defect state Pb0 to form Bi+ and Pb2+ and also substitutes Pb0.•Enhanced ZT of 100 times the best previous reports on MAPbBr3 single crystals achieved.
Organic-inorganic hybrid metal halide perovskites have emerged as a promising candidate for low-temperature thermoelectric conversion. However, challenges remain in heavily doping bulk perovskite single crystals without phase segregation or self-doping compensation issues to increase the carrier concentration. Previous efforts to enhance their thermoelectric performance rely on photoexcitation or surface/interface doping, which is not suitable for bulk devices to work in dark. This study achieves high monovalent and trivalent doping concentrations of up to 5 % in bulk single crystals of MAPbI3 and MAPbBr3 without phase segregation or defect formation. For monovalent doping, K+ and Li+ are incorporated into the perovskite lattice as interstitials. The resulting lattice distortion/microstrain enhances the electrical conductivity by 10 ∼ 100 times of undoped samples at 420 K. Trivalent doping using SbCl3, BiBr3, and BiI3 significantly enhances the carrier concentration and electrical conductivity, up to 1012 cm−3 and 0.038 S m−1 for MAPbBr3 with 10 % BiI3 at 465 K, respectively, which is 105 times of the undoped samples and 10 times of the best reports on doped MAPbBr3. Interestingly, the Bi3+ dopant oxidizes the deep defect state Pb0, resulting in Bi+ and Pb2+ formation and contributing to the enhanced electrical conductivity. Enhanced thermoelectric figure of merit (ZT) is achieved in MAPbBr3 with 5 % BiI3 at 315 K, almost 100 times of the best reports on doped MAPbBr3. This study provides fundamental understanding of doping-modulated microstructural, charge carrier, and thermoelectric properties of hybrid halide perovskites, offering potential doping strategies to realize the theoretically predicted promising thermoelectric properties in their bulk single crystals for practical thermoelectric devices. The doping-modulated carrier transport will also guide the optimization of optoelectronic applications of halide perovskites for solar cells, light emitters, and photodetectors.
The metallic layers are an essential part of MEMS (micro electromechanical system) devices, and their deposition process must be accurately controlled; this may lead to difficulties as there are many ...input parameters for such a process. This research focuses on the input parameters’ effects on the Ni pulse-reverse electroplating. A neural network was constructed to characterize the pulse-reverse nickel electroforming process parameters. The sample training has accurately established the mapping relationship between input and output parameters. The nickel layer thickness and surface roughness prediction in the pulse-reverse electroplating process was realized and verified by experimental tests with a test error of 3.3%. Then, the effect of direct and reverse current density, deposition time, structure width, and stirring speed as input parameters on the thickness and surface roughness are investigated. Finally, a novel 4D diagram has been developed to derive the optimal values of direct and reverse current density relative to thickness, surface roughness, and deposition time. This diagram can help researchers and industries find suitable parameters to achieve the desired deposited Ni layer’s properties.
PDF
