Now showing items 21-40 of 56854

    • Wafer-scale single-crystal monolayer graphene grown on sapphire substrate

      Li, Junzhu; Chen, Mingguang; Samad, Abdus; Dong, Haocong; Ray, Avijeet; Zhang, Junwei; Jiang, Xiaochuan; Schwingenschlögl, Udo; Domke, Jari; Chen, Cailing; Han, Yu; Fritz, Torsten; Ruoff, Rodney S.; Tian, Bo; Zhang, Xixiang (Nature Materials, Springer Science and Business Media LLC, 2022-01-20) [Article]
      The growth of inch-scale high-quality graphene on insulating substrates is desirable for electronic and optoelectronic applications, but remains challenging due to the lack of metal catalysis. Here we demonstrate the wafer-scale synthesis of adlayer-free ultra-flat single-crystal monolayer graphene on sapphire substrates. We converted polycrystalline Cu foil placed on Al2O3(0001) into single-crystal Cu(111) film via annealing, and then achieved epitaxial growth of graphene at the interface between Cu(111) and Al2O3(0001) by multi-cycle plasma etching-assisted–chemical vapour deposition. Immersion in liquid nitrogen followed by rapid heating causes the Cu(111) film to bulge and peel off easily, while the graphene film remains on the sapphire substrate without degradation. Field-effect transistors fabricated on as-grown graphene exhibited good electronic transport properties with high carrier mobilities. This work breaks a bottleneck of synthesizing wafer-scale single-crystal monolayer graphene on insulating substrates and could contribute to next-generation graphene-based nanodevices.
    • Statistical analysis of multi-day solar irradiance using a threshold time series model

      de Jesus Euan Campos, Carolina; Sun, Ying; Reich, Brian J. (Environmetrics, Wiley, 2022-01-20) [Article]
      The analysis of solar irradiance has important applications in predicting solar energy production from solar power plants. Although the sun provides every day more energy than we need, the variability caused by environmental conditions affects electricity production. Recently, new statistical models have been proposed to provide stochastic simulations of high-resolution data to downscale and forecast solar irradiance measurements. Most of the existing models are linear and highly depend on normality assumptions. However, solar irradiance shows strong nonlinearity and is only measured during the day time. Thus, we propose a new multi-day threshold autoregressive model to quantify the variability of the daily irradiance time series. We establish the sufficient conditions for our model to be stationary, and we develop an inferential procedure to estimate the model parameters. When we apply our model to study the statistical properties of observed irradiance data in Guadeloupe island group, a French overseas region located in the Southern Caribbean Sea, we are able to characterize two states of the irradiance series. These states represent the clear-sky and non-clear sky regimes. Using our model, we are able to simulate irradiance series that behave similarly to the real data in mean and variability, and more accurate forecasts compared to linear models.
    • Enzymatic Hydrolysis Lignin-Derived Porous Carbons through Ammonia Activation: Activation Mechanism and Charge Storage Mechanism

      Jian, Wenbin; Zhang, Wenli; Wu, Bingchi; Wei, Xueer; Liang, Wanling; Zhang, Xiaoshan; Wen, Fuwang; Zhao, Lei; Yin, Jian; Lu, Ke; Qiu, Xueqing (ACS Applied Materials & Interfaces, American Chemical Society (ACS), 2022-01-20) [Article]
      The low energy density and low cost performance of electrochemical capacitors (ECs) are the principal factors that limit the wide applications of ECs. In this work, we used enzymatic hydrolysis lignin as the carbon source and an ammonia activation methodology to prepare nitrogen-doped lignin-derived porous carbon (NLPC) electrode materials with high specific surface areas. We elucidated the free radical mechanism of ammonia activation and the relationship between nitrogen doping configurations, doping levels, and preparation temperatures. Furthermore, we assembled NLPC∥NLPC symmetric ECs and NLPC∥Zn asymmetric ECs using aqueous sulfate electrolytes. Compared with the ECs using KOH aqueous electrolyte, the energy densities of NLPC∥NLPC and NLPC∥Zn ECs were significantly improved. The divergence of charge storage characteristics in KOH, Na2SO4, and ZnSO4 electrolytes were compared by analyzing their area surface capacitance. This work provides a strategy for the sustainable preparation of lignin-derived porous carbons toward ECs with high energy densities.
    • Ecosystem design as an avenue for improving services provided by carbonate producing marine ecosystems

      Westphal, Hildegard; Murphy, Gary N.; Doo, Steve S.; Mann, Thomas; Petrovic, Alexander; Schmidt, Christiane; Stuhr, Marleen (PeerJ, PeerJ, 2022-01-20) [Article]
      Ecosystem Design (ED) is an approach for constructing habitats that places human needs for ecosystem services at the center of intervention, with the overarching goal of establishing self-sustaining habitats which require limited management. This concept was originally developed for use in mangrove ecosystems, and is understandably controversial, as it markedly diverges from other protection approaches that assign human use a minor priority or exclude it. However, the advantage of ED lies within the considered implementation of these designed ecosystems, thus preserving human benefits from potential later disturbances. Here, we outline the concept of ED in tropical carbonate depositional systems and discuss potential applications to aid ecosystem services such as beach nourishment and protection of coastlines and reef islands at risk from environmental and climate change, CO2 sequestration, food production, and tourism. Biological carbonate sediment production is a crucial source of stability of reef islands and reef-rimmed coastlines. Careful implementation of designed carbonate depositional ecosystems could help counterbalance sea-level rise and manage documented erosion effects of coastal constructions. Importantly, adhering to the core ethos of ED, careful dynamic assessments which provide a balanced approach to maximizing ecosystem services (e.g., carbonate production), should identify and avoid any potential damages to existing functioning ecosystems.
    • How to Find the Right RNA-Sensing CRISPR-Cas System for an In Vitro Application

      Díaz-Galicia, Escarlet; Grunberg, Raik; Arold, Stefan T. (Biosensors, MDPI AG, 2022-01-19) [Article]
      CRISPR-Cas systems have a great and still largely untapped potential for in vitro applications, in particular, for RNA biosensing. However, there is currently no systematic guide on selecting the most appropriate RNA-targeting CRISPR-Cas system for a given application among thousands of potential candidates. We provide an overview of the currently described Cas effector systems and review existing Cas-based RNA detection methods. We then propose a set of systematic selection criteria for selecting CRISPR-Cas candidates for new applications. Using this approach, we identify four candidates for in vitro RNA.
    • Interfaces between Pb-Free Double Perovskite Cs2NaBiI6 and MXenes Sc2CO2 and Sc2C(OH)2

      Albar, Arwa; Schwingenschlögl, Udo (The Journal of Physical Chemistry Letters, American Chemical Society (ACS), 2022-01-19) [Article]
      First-principles calculations are used to explore the electronic properties of the interfaces between the Pb-free double perovskite Cs2NaBiI6 and the MXenes Sc2CO2 and Sc2C(OH)2. The effect of the termination group on the stability, ionization potential, electron affinity, and band alignment is investigated. We find a type II band alignment at the Cs2NaBiI6/Sc2CO2 interface, which permits charge transfer, and a type III band alignment at the Cs2NaBiI6/Sc2C(OH)2 interface, which results in electron–hole recombination. Sc2CO2 turns out to be highly promising for solar cell applications due to an almost ideal ionization potential difference to Cs2NaBiI6.
    • Decision rules for determining terrestrial movement and the consequences for filtering high-resolution global positioning system tracks: a case study using the African lion ( Panthera leo )

      Gunner, Richard; Wilson, Rory P.; Holton, Mark D.; Hopkins, Phil; Bell, Stephen H.; Marks, Nikki J.; Bennett, Nigel C.; Ferreira, Sam; Govender, Danny; Viljoen, Pauli; Bruns, Angela; van Schalkwyk, O. Louis; Bertelsen, Mads F.; Duarte, Carlos M.; van Rooyen, Martin C.; Tambling, Craig J.; Göppert, Aoife; Diesel, Delmar; Scantlebury, D. Michael (Journal of The Royal Society Interface, The Royal Society, 2022-01-19) [Article]
      The combined use of global positioning system (GPS) technology and motion sensors within the discipline of movement ecology has increased over recent years. This is particularly the case for instrumented wildlife, with many studies now opting to record parameters at high (infra-second) sampling frequencies. However, the detail with which GPS loggers can elucidate fine-scale movement depends on the precision and accuracy of fixes, with accuracy being affected by signal reception. We hypothesized that animal behaviour was the main factor affecting fix inaccuracy, with inherent GPS positional noise (jitter) being most apparent during GPS fixes for non-moving locations, thereby producing disproportionate error during rest periods. A movement-verified filtering (MVF) protocol was constructed to compare GPS-derived speed data with dynamic body acceleration, to provide a computationally quick method for identifying genuine travelling movement. This method was tested on 11 free-ranging lions (Panthera leo) fitted with collar-mounted GPS units and tri-axial motion sensors recording at 1 and 40 Hz, respectively. The findings support the hypothesis and show that distance moved estimates were, on average, overestimated by greater than 80% prior to GPS screening. We present the conceptual and mathematical protocols for screening fix inaccuracy within high-resolution GPS datasets and demonstrate the importance that MVF has for avoiding inaccurate and biased estimates of movement.
    • 2′,3′-cAMP treatment mimics the stress molecular response in Arabidopsis thaliana

      Chodasiewicz, Monika; Kerber, Olga; Gorka, Michal; Moreno, Juan C; Maruri Lopez, Israel; Minen, Romina I; Sampathkumar, Arun; Nelson, Andrew D L; Skirycz, Aleksandra (Plant Physiology, Oxford University Press (OUP), 2022-01-19) [Article]
      The role of the RNA degradation product 2’,3’-cyclic adenosine monophosphate (2’,3’-cAMP) is poorly understood. Recent studies have identified 2’,3’-cAMP in plant material and determined its role in stress signaling. The level of 2’,3’-cAMP increases upon wounding, in the dark, and under heat, and 2’,3’-cAMP binding to an RNA-binding protein, Rbp47b, promotes stress granule (SG) assembly. To gain further mechanistic insights into the function of 2’,3’-cAMP, we used a multi-omics approach by combining transcriptomics, metabolomics, and proteomics to dissect the response of Arabidopsis (Arabidopsis thaliana) to 2’,3’-cAMP treatment. We demonstrated that 2’,3’-cAMP is metabolized into adenosine, suggesting that the well-known cyclic nucleotide–adenosine pathway of human cells might also exist in plants. Transcriptomics analysis revealed only minor overlap between 2’,3’-cAMP- and adenosine-treated plants, suggesting that these molecules act through independent mechanisms. Treatment with 2’,3’-cAMP changed the levels of hundreds of transcripts, proteins, and metabolites, many previously associated with plant stress responses, including protein and RNA degradation products, glucosinolates, chaperones, and SG components. Finally, we demonstrated that 2’,3’-cAMP treatment influences the movement of processing bodies, confirming the role of 2’,3’-cAMP in the formation and motility of membraneless organelles.
    • Dynamic Molecular Conformational Change Leading to Energy Transfer in F8-5% BSP Copolymer Revealed by Single-Molecule Spectroscopy

      Yan, Hao; Tseng, Tzu-Wei; Omagari, Shun; Hamilton, Iain; Nakamura, Tomonori; Vacha, Martin; Kim, Ji Seon (The Journal of Chemical Physics, AIP Publishing, 2022-01-18) [Article]
      Polyfluorene-based copolymers such as poly(9,9-dioctylfluorene)-alt-5% (bis-N,N'-(4-butylphenyl)-bis-N,N'-phenyl-1,4-phenylenediamine) (F8-5% BSP) are efficient blue emitting polymers with various electronic phases: F8 blue-emitting glassy phase, F8 ordered more red-emitting β-phase, and F8/BSP charge transfer (CT) state. Polymer light-emitting device performance and color purity can be significantly improved by forming β-phase segments. However, the role of β-phase on energy transfer (ET) among glassy F8, β-phase and F8/BSP CT state is unclear. Herein, we identify dynamic molecular conformation-controlled ET from locally-excited states to either CT state or β-phase in light-emitting copolymers. By conducting single-molecule spectroscopy for single F8-5% BSP chains, we find inefficient intra-chain ET from glassy segments to the CT state, while efficient ET from the glassy to the β-phase. Spontaneous and reversible CT on-off emission is observed both in the presence and absence of the β-phase. The DFT calculations reveal the origin of the on-chain CT state and indicate this CT emission on-off switching behavior could be related to molecule torsional motion between BSP and F8 units. The population of the CT state by ET can be increased via through-space interaction between the F8 block and the BSP unit on a self-folded chain. Temperature-dependent single-molecule spectroscopy confirms such interaction showing a gradual increase in intensity of the CT emission with the temperature. Based on these observations, we propose the dynamic molecular motion-induced conformation change as the origin of the glassy-to-CT energy transfer, and thermal energy may provide the activation for such change to enhance the ET from glassy or β-phases to the CT state.
    • A Stretchable Fiber with Tunable Stiffness for Programmable Shape Change of Soft Robots

      Chellattoan, Ragesh; Lubineau, Gilles (Soft Robotics, Mary Ann Liebert Inc, 2022-01-18) [Article]
      All soft robots require the same functionality, that is, controlling the shape of a structure made from soft materials. However, existing approaches for shape control of soft robots are primarily dominated by modular pneumatic actuators, which require multichambers and complex flow control components. Nature shows exciting examples of manipulation (shape change) in animals, such as worms, using a single-chambered soft body and programmable stiffness changes in the skin; controlling the spatial distribution of changes in stiffness enables achieving complex shape evolutions. However, such stiffness control requires a drastic membrane stiffness contrast between stiffened and nonstiffened states. Generally, this is extremely challenging to accomplish in stretchable materials. Inspired by longitudinal muscle fibers in the skin of worms, we developed a new concept for fabricating a hybrid fiber with tunable stiffness, that is, a fiber comprising both stiff and soft parts connected in a series. A substantial change in membrane stiffness was then observed by the locking/unlocking of the soft part. Our proposed hybrid fiber cyclically produced a membrane stiffness contrast of more than 100 × in less than 6 s using an input power of 3 W. A network of these hybrid fibers with tunable stiffness could manipulate a single-chambered soft body in multiple directions and transform it into a complex shape by selectively varying the stiffness at different locations.
    • Deformable Sphere Impact On Resting Droplets

      Rabbi, Rafsan; Kiyama, Akihito; Allen, John; Truscott, Tadd (Journal of Fluids Engineering, ASME International, 2022-01-18) [Article]
      Several different rebound behaviors occur when a solid object impacts a resting liquid droplet. High-speed imaging reveals the various droplet rebound phenomena from two spheres with very different elasticities.
    • An Updated Corner-Frequency Model for Stochastic Finite-Fault Ground-Motion Simulation

      Tang, Yuxiang (Bulletin of the Seismological Society of America, Seismological Society of America (SSA), 2022-01-18) [Article]
      ABSTRACT Stochastic finite-fault ground-motion simulation is widely used in various scientific and engineering applications. However, the current theoretical modeling of the corner frequency used in the source spectrum model is problematic as it does not consider the impact of rupture velocity. This article provides a modification of the current corner-frequency modeling and establishes a correlation between corner frequency and rupture velocity, making the source spectrum model more theoretically consistent. An additional inspection of the source-duration model is provided, and the appropriateness of the application of the widely used 1/f0 source-duration model is discussed. A detailed comparison between the updated corner-frequency model and the currently used model (embodied in EXSIM) is provided for various magnitudes. For validation purposes, the updated corner-frequency and source-duration model is applied to predict the ground motions on rock sites during the 2012 ML 5.4 Moe earthquake that occurred in southeastern Australia and the 2014 Ms 6.5 Ludian earthquake that occurred in southwestern China. The results show that the updated model is reliable for providing more accurate estimates of corner frequency, source duration, and ground-motion amplitudes with smaller average residuals than the currently used model.
    • Combustion chemistry of alkenes and alkadienes

      Zhou, Chong Wen; Farooq, Aamir; Yang, Lijun; Mebel, Alexander M. (Progress in Energy and Combustion Science, Elsevier BV, 2022-01-18) [Article]
      Alkenes formed, during the refining of crude oil, by cracking the heavier fractions are present in transportation fuels in significant amounts, up to as much as 15–20% in gasoline. Moreover, alkenes are also the major intermediate products of the oxidation of alkanes, which play a significant role in autoignition chemistry. This review has assessed the recent progress in gas-phase detailed kinetic model development for species with C=C double bond, mostly C2–C10 alkenes and 1,3-butadiene. The compiled knowledge on alkene combustion chemistry enabled a better understanding of the influence of the number and the position of the C=C double bond on the chemical kinetics and hence combustion behavior of alkenes in engines. At first, the article gives an extensive overview of fundamental combustion experiments by considering studies of C2–C10 alkenes and 1,3-butadiene in shock tubes, rapid compression machines, laminar flames, and jet-stirred and flow reactors. The value of the data from such experiments is critically discussed. Secondly, this article highlights the important reaction classes involved in alkene oxidation over low-, intermediate- and high-temperature ranges. Combustion chemistry covering C2 to C10 alkenes, with a special emphasis on C2 to C7 isomers is discussed by presenting a large body of experimental and modeling investigations. Detailed chemistry differences between alkene isomers and also between alkenes and alkanes are also addressed. Thirdly, the article presents important reaction pathways for PAH precursor formation in different alkenes. Finally, a summary of the distinguishing features of alkene combustion chemistry and an outlook towards future research in this area are presented. This review is focused on linear and branched chain alkenes, and the chemistry of cyclo-alkenes is not included.
    • Effects of Vertical Molecular Stratifications and Microstructures on the Properties of Fullerene-Free Organic Solar Cells

      Peña, Top Archie Dela; Ma, Ruijie; Sharma, Anirudh; Xing, Zengshan; Jin, Zijing; Wang, Jiannong; Baran, Derya; Weng, Lu-Tao; Yan, He; Wong, Kam Sing (Advanced Photonics Research, Wiley, 2022-01-18) [Article]
      From the past years, the most commonly reported state-of-the-art binary bulk heterojunction organic solar cells (OSCs) are mostly based on mixtures of polymer donors and fullerene-free acceptors (polymer:NFA). However, along with it are a number of contradictory propositions, including (but not limited to) strategies to reduce energy loss and improve photocurrent generation through energy level alignments. Due to the resulting high similarity of molecular fragments from polymer:NFA heterojunctions, the effects of vertical molecular stratification are not yet well studied. Herein, the time-of-flight secondary ion mass spectrometry (ToF-SIMS) molecular depth profiling reveals a vertical stratification in PM6:IT-4Cl and illustrates how it can significantly influence the photovoltaic properties. The said inhomogeneity is also bound to introduce microstructure variations within device active layers. Consequently, it is systematically demonstrated how thin-film microstructures can influence optoelectronic properties, wherein important metrics (e.g., energy losses and molecular energy offsets) are highly dependent. Thus, the understanding from this work provides foundations for more precise development of strategies to further advance OSC technology in future studies.
    • Fabrication of Perovskite/Si periodic microwire arrays via micro-pump fluidic strategy for optelectronics applications

      Bin, Xin; Roqan, Iman S. (IEEE, 2022-01-18) [Conference Paper]
      We explore a micro-pump strategy for injecting perovskite materials into Si micro-channels, allowing fabrication of many perovskite micro-wires (MWs) to form inside the regularly-spaced (periodic) Si micro-grooves (~ 1000 MWs/mm). Mask-free laser interference lithography is used to produce periodic Si micro-channels. The SiO2 layer is deposited on the Si array before pumping perovskite to enhance the device performance. We demonstrate a cost-effective zero-waste fabrication method of highly responsive photodetectors based on uniform perovskite MWs/SiO2/Si periodic arrays.
    • Global biodiversity patterns of marine forests of brown macroalgae

      Fragkopoulou, Eliza; Serrão, Ester A.; De Clerck, Olivier; Costello, Mark J.; Araújo, Miguel B.; Duarte, Carlos M.; Krause-Jensen, Dorte; Assis, Jorge (Global Ecology and Biogeography, Wiley, 2022-01-17) [Article]
      Aim Marine forests of brown macroalgae create essential habitats for coastal species and support invaluable ecological services. Here, we provide the first global analysis of species richness and endemicity of both the kelp and fucoid biomes. Location Global. Time period Contemporary. Major taxa studied Marine forests of brown macroalgae, formed by kelp (here defined as orders Laminariales, Tilopteridales and Desmarestiales) and fucoid (order Fucales), inhabiting subtidal and intertidal environments. Methods We coupled a large dataset of macroalgal observations (420 species, 1.01 million records) with a high-resolution dataset of relevant environmental predictors (i.e., light, temperature, salinity, nitrate, wave energy and ice coverage) to develop stacked species distribution models (stacked SDMs) and yield estimates of global species richness and endemicity. Results Temperature and light were the main predictors shaping the distribution of subtidal species, whereas wave energy, temperature and salinity were the main predictors of intertidal species. The highest regional species richness for kelp was found in the north-east Pacific (maximum 32 species) and for fucoids in south-east Australia (maximum 53 species), supporting the hypothesis that these regions were the evolutionary sources of global colonization by brown macroalgae. Locations with low species richness coincided between kelp and fucoid, occurring mainly at higher latitudes (e.g., Siberia) and the Baltic Sea, where extensive ice coverage and low-salinity regimes prevail. Regions of high endemism for both groups were identified in the Galapagos Islands, Antarctica, South Africa and East Russia. Main conclusions We estimated the main environmental drivers and limits shaping the distribution of marine forests of brown macroalgae and mapped biogeographical centres of species richness and endemicity, which largely coincided with the expectation from previous evolutionary hypotheses. The mapped biodiversity patterns can serve as new baselines for planning and prioritizing locations for conservation, management and climate change mitigation strategies, flagging threatened marine forest regions under different climate change scenarios
    • Brilliantia kiribatiensis, a new genus and species of Cladophorales (Chlorophyta) from the remote coral reefs of the Southern Line Islands, Pacific Ocean

      Leliaert, Frederik; Kelly, Emily L.A.; Janouškovec, Jan; Fox, Michael D.; Johnson, Maggie D.; Redfern, Farran M.; Eria, Taati; Haas, Andreas F.; Sala, Enric; Sandin, Stuart A.; Smith, Jennifer E. (Journal of Phycology, Wiley, 2022-01-17) [Article]
      The marine green alga Brilliantia kiribatiensis gen. et sp. nov. is described from samples collected from the coral reefs of the Southern Line Islands, Republic of Kiribati, Pacific Ocean. Phylogenetic analysis of sequences of the large- and small-subunit rDNA and the rDNA internal transcribed spacer region revealed that Brilliantia is a member of the Boodleaceae (Cladophorales), containing the genera Apjohnia, Boodlea, Cladophoropsis, Chamaedoris, Phyllodictyon, and Struvea. Within this clade it formed a distinct lineage, sister to Struvea elegans, but more distantly related to the bona fide Struvea species (including the type S. plumosa). Brilliantia differs from the other genera by having a very simple architecture forming upright, unbranched, single-celled filaments attached to the substratum by a rhizoidal mat. Cell division occurs by segregative cell division only at the onset of reproduction. Based on current sample collection, B. kiribatiensis seems to be largely restricted to the Southern Line Islands, although it was also observed on neighboring islands, including Orona Atoll in the Phoenix Islands of Kiribati, and the Rangiroa and Takapoto Atolls in the Tuamotus of French Polynesia. This discovery highlights the likeliness that there is still much biodiversity yet to be discovered from these remote and pristine reefs of the central Pacific.
    • Antibiotics reduce bacterial load in Exaiptasia diaphana, but biofilms hinder its development as a gnotobiotic coral model

      Hartman, Leon M.; Blackall, Linda L.; van Oppen, Madeleine J. H. (Access Microbiology, Microbiology Society, 2022-01-17) [Article]
      Coral reefs are declining due to anthropogenic disturbances, including climate change. Therefore, improving our understanding of coral ecosystems is vital, and the influence of bacteria on coral health has attracted particular interest. However, a gnotobiotic coral model that could enhance studies of coral–bacteria interactions is absent. To address this gap, we tested the ability of treatment with seven antibiotics for 3 weeks to deplete bacteria in Exaiptasia diaphana, a sea anemone widely used as a coral model. Digital droplet PCR (ddPCR) targeting anemone Ef1-α and bacterial 16S rRNA genes was used to quantify bacterial load, which was found to decrease six-fold. However, metabarcoding of bacterial 16S rRNA genes showed that alpha and beta diversity of the anemone-associated bacterial communities increased significantly. Therefore, gnotobiotic E. diaphana with simplified, uniform bacterial communities were not generated, with biofilm formation in the culture vessels most likely impeding efforts to eliminate bacteria. Despite this outcome, our work will inform future efforts to create a much needed gnotobiotic coral model.
    • Self-Assembly and Regrowth of Metal Halide Perovskite Nanocrystals for Optoelectronic Applications

      Liu, Jiakai; Zheng, Xiaopeng; Mohammed, Omar F.; Bakr, Osman (Accounts of Chemical Research, American Chemical Society (ACS), 2022-01-16) [Article]
      Conspectus Over the past decade, the impressive development of metal halide perovskites (MHPs) has made them leading candidates for applications in photovoltaics (PVs), X-ray scintillators, and light-emitting diodes (LEDs). Constructing MHP nanocrystals (NCs) with promising optoelectronic properties using a low-cost approach is critical to realizing their commercial potential. Self-assembly and regrowth techniques provide a simple and powerful “bottom-up” platform for controlling the structure, shape, and dimensionality of MHP NCs. The soft ionic nature of MHP NCs, in conjunction with their low formation energy, rapid anion exchange, and ease of ion migration, enables the rearrangement of their overall appearance via self-assembly or regrowth. Because of their low formation energy and highly dynamic surface ligands, MHP NCs have a higher propensity to regrow than conventional hard-lattice NCs. Moreover, their self-assembly and regrowth can be achieved simultaneously. The self-assembly of NCs into close-packed, long-range-ordered mesostructures provides a platform for modulating their electronic properties (e.g., conductivity and carrier mobility). Moreover, assembled MHP NCs exhibit collective properties (e.g., superfluorescence, renormalized emission, longer phase coherence times, and long exciton diffusion lengths) that can translate into dramatic improvements in device performance. Further regrowth into fused MHP nanostructures with the removal of ligand barriers between NCs could facilitate charge carrier transport, eliminate surface point defects, and enhance stability against moisture, light, and electron-beam irradiation. However, the synthesis strategies, diversity and complexity of structures, and optoelectronic applications that emanate from the self-assembly and regrowth of MHPs have not yet received much attention. Consequently, a comprehensive understanding of the design principles of self-assembled and fused MHP nanostructures will fuel further advances in their optoelectronic applications. In this Account, we review the latest developments in the self-assembly and regrowth of MHP NCs. We begin with a survey of the mechanisms, driving forces, and techniques for controlling MHP NC self-assembly. We then explore the phase transition of fused MHP nanostructures at the atomic level, delving into the mechanisms of facet-directed connections and the kinetics of their shape-modulation behavior, which have been elucidated with the aid of high-resolution transmission electron microscopy (HRTEM) and first-principles density functional theory calculations of surface energies. We further outline the applications of assembled and fused nanostructures. Finally, we conclude with a perspective on current challenges and future directions in the field of MHP.
    • Development in forward Osmosis-Membrane distillation hybrid system for wastewater treatment

      Ibrar, Ibrar; Yadav, Sudesh; Naji, Osamah; Alanezi, Adnan Alhathal; Ghaffour, NorEddine; Déon, Sébastien; Subbiah, Senthilmurugan; Altaee, Ali (Separation and Purification Technology, Elsevier BV, 2022-01-16) [Article]
      Water scarcity is one of the major issues that has put economic growth, societal stability, and ecosystem balance unstable. Wastewater reuse has been recognised as a viable method for securing potable water supply. Due to its inherent advantages over pressure-driven and energy-intensive reverse osmosis (RO), forward osmosis (FO) is one of the most researched technologies for wastewater reuse applications. However, the draw solution (DS) regeneration stage is one of the key bottlenecks of the process. Membrane distillation (MD), on the other hand, is an emerging technology that could provide a cost-effective thermally-driven purification process, especially when combined with waste heat or solar thermal. Nevertheless, the MD process also has several drawbacks, such as membrane pore wetting. The MD process can effectively regenerate the FO draw solution and produce high-quality water when integrated with the FO process. Within the hybrid process, the FO membrane removes the contaminants from the feed solution and the MD process is only used to regenerate the DS with no significant membrane wetting. It is, therefore, important to study the integrated FO-MD process to overcome the limitations of individual membrane processes. Integrated FO-MD economics, process design, and modelling of different applications are thoroughly reviewed in this contribution. Future research directions and prospects for scale-up are suggested.