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  • A zero liquid discharge system integrating multi-effect distillation and evaporative crystallization for desalination brine treatment

    Chen, Qian; Burhan, Muhammad; Shahzad, Muhammad Wakil; Ybyraiymkul, Doskhan; Akhtar, Faheem; Li, Yong; Ng, Kim Choon (Desalination, Elsevier BV, 2021-01-13) [Article]
    With growing global desalination capacity, brine from desalination plants has become an environmental threat to the ecosystems. One sustainable method for brine treatment is to develop zero liquid discharge systems that completely convert seawater into freshwater and salts. This paper presents a zero liquid discharge system, which consists of multi-effect distillation and evaporative crystallization, to treat desalination brine with a salinity of 70 g/kg. A thermodynamic analysis is firstly conducted for the proposed system. The specific heat consumption, specific heat transfer area, and Second-law efficiency are found to be 600–1100 kJ/kg, 110–340 m2/(kg/s), and 10–17%, respectively. The heat consumption can be effectively reduced by increasing the number of MED stages, while the specific heat transfer area decreases significantly with higher heat source temperatures. Based on the thermodynamic performance, a techno-economic analysis is conducted for the proposed system, and the specific cost is calculated to be $4.17/m3. Cost reduction can be achieved via employing cost-effective heat sources, reducing heat consumption, and scaling up the system. By selling the freshwater and salt crystals, the system will be more competitive than other existing brine treatment methods.
  • Change-point detection using spectral PCA for multivariate time series

    Jiao, Shuhao; Shen, Tong; Yu, Zhaoxia; Ombao, Hernando (arXiv, 2021-01-12) [Preprint]
    We propose a two-stage approach Spec PC-CP to identify change points in multivariate time series. In the first stage, we obtain a low-dimensional summary of the high-dimensional time series by Spectral Principal Component Analysis (Spec-PCA). In the second stage, we apply cumulative sum-type test on the Spectral PCA component using a binary segmentation algorithm. Compared with existing approaches, the proposed method is able to capture the lead-lag relationship in time series. Our simulations demonstrate that the Spec PC-CP method performs significantly better than competing methods for detecting change points in high-dimensional time series. The results on epileptic seizure EEG data and stock data also indicate that our new method can efficiently {detect} change points corresponding to the onset of the underlying events.
  • Impacts of hypoxic events surpass those of future ocean warming and acidification

    Sampaio, Eduardo; Santos, Catarina; Rosa, Inês C.; Ferreira, Verónica; Pörtner, Hans-Otto; Duarte, Carlos M.; Levin, Lisa A.; Rosa, Rui (Nature Ecology & Evolution, Springer Science and Business Media LLC, 2021-01-11) [Article]
    Over the past decades, three major challenges to marine life have emerged as a consequence of anthropogenic emissions: ocean warming, acidification and oxygen loss. While most experimental research has targeted the first two stressors, the last remains comparatively neglected. Here, we implemented sequential hierarchical mixed-model meta-analyses (721 control–treatment comparisons) to compare the impacts of oxygen conditions associated with the current and continuously intensifying hypoxic events (1–3.5 O2 mg l−1) with those experimentally yielded by ocean warming (+4 °C) and acidification (−0.4 units) conditions on the basis of IPCC projections (RCP 8.5) for 2100. In contrast to warming and acidification, hypoxic events elicited consistent negative effects relative to control biological performance—survival (–33%), abundance (–65%), development (–51%), metabolism (–33%), growth (–24%) and reproduction (–39%)—across the taxonomic groups (mollusks, crustaceans and fish), ontogenetic stages and climate regions studied. Our findings call for a refocus of global change experimental studies, integrating oxygen concentration drivers as a key factor of ocean change. Given potential combined effects, multistressor designs including gradual and extreme changes are further warranted to fully disclose the future impacts of ocean oxygen loss, warming and acidification.
  • The skeletome of the red coral Corallium rubrum indicates an independent evolution of biomineralization process in octocorals

    Le Roy, Nathalie; Ganot, Philippe; Aranda, Manuel; Allemand, Denis; Tambutté, Sylvie (BMC Ecology and Evolution, Springer Science and Business Media LLC, 2021-01-11) [Article]
    Abstract Background The process of calcium carbonate biomineralization has arisen multiple times during metazoan evolution. In the phylum Cnidaria, biomineralization has mostly been studied in the subclass Hexacorallia (i.e. stony corals) in comparison to the subclass Octocorallia (i.e. red corals); the two diverged approximately 600 million years ago. The precious Mediterranean red coral, Corallium rubrum, is an octocorallian species, which produces two distinct high-magnesium calcite biominerals, the axial skeleton and the sclerites. In order to gain insight into the red coral biomineralization process and cnidarian biomineralization evolution, we studied the protein repertoire forming the organic matrix (OM) of its two biominerals. Results We combined High-Resolution Mass Spectrometry and transcriptome analysis to study the OM composition of the axial skeleton and the sclerites. We identified a total of 102 OM proteins, 52 are found in the two red coral biominerals with scleritin being the most abundant protein in each fraction. Contrary to reef building corals, the red coral organic matrix possesses a large number of collagen-like proteins. Agrin-like glycoproteins and proteins with sugar-binding domains are also predominant. Twenty-seven and 23 proteins were uniquely assigned to the axial skeleton and the sclerites, respectively. The inferred regulatory function of these OM proteins suggests that the difference between the two biominerals is due to the modeling of the matrix network, rather than the presence of specific structural components. At least one OM component could have been horizontally transferred from prokaryotes early during Octocorallia evolution. Conclusion Our results suggest that calcification of the red coral axial skeleton likely represents a secondary calcification of an ancestral gorgonian horny axis. In addition, the comparison with stony coral skeletomes highlighted the low proportion of similar proteins between the biomineral OMs of hexacorallian and octocorallian corals, suggesting an independent acquisition of calcification in anthozoans.
  • MAAS: Multi-modal Assignation for Active Speaker Detection

    León-Alcázar, Juan; Heilbron, Fabian Caba; Thabet, Ali Kassem; Ghanem, Bernard (arXiv, 2021-01-11) [Preprint]
    Active speaker detection requires a solid integration of multi-modal cues. While individual modalities can approximate a solution, accurate predictions can only be achieved by explicitly fusing the audio and visual features and modeling their temporal progression. Despite its inherent muti-modal nature, current methods still focus on modeling and fusing short-term audiovisual features for individual speakers, often at frame level. In this paper we present a novel approach to active speaker detection that directly addresses the multi-modal nature of the problem, and provides a straightforward strategy where independent visual features from potential speakers in the scene are assigned to a previously detected speech event. Our experiments show that, an small graph data structure built from a single frame, allows to approximate an instantaneous audio-visual assignment problem. Moreover, the temporal extension of this initial graph achieves a new state-of-the-art on the AVA-ActiveSpeaker dataset with a mAP of 88.8\%.
  • Efficient bifacial monolithic perovskite/silicon tandem solar cells via bandgap engineering

    de Bastiani, Michele; Mirabelli, Alessandro J.; Hou, Yi; Gota, Fabrizio; Aydin, Erkan; Allen, Thomas; Troughton, Joel; Subbiah, Anand Selvin; Isikgor, Furkan Halis; Liu, Jiang; Xu, Lujia; Chen, Bin; Van Kerschaver, Emmanuel; Baran, Derya; Fraboni, Beatrice; Salvador, Michael F.; Paetzold, Ulrich W.; Sargent, E.; De Wolf, Stefaan (Nature Energy, Springer Science and Business Media LLC, 2021-01-11) [Article]
    Bifacial monolithic perovskite/silicon tandem solar cells exploit albedo—the diffuse reflected light from the environment—to increase their performance above that of monofacial perovskite/silicon tandems. Here we report bifacial tandems with certified power conversion efficiencies >25% under monofacial AM1.5G 1 sun illumination that reach power-generation densities as high as ~26 mW cm–2 under outdoor testing. We investigated the perovskite bandgap required to attain optimized current matching under a variety of realistic illumination and albedo conditions. We then compared the properties of these bifacial tandems exposed to different albedos and provide energy yield calculations for two locations with different environmental conditions. Finally, we present a comparison of outdoor test fields of monofacial and bifacial perovskite/silicon tandems to demonstrate the added value of tandem bifaciality for locations with albedos of practical relevance.
  • Coating of Conducting and Insulating Threads with Porous MOF Particles through Langmuir-Blodgett Technique

    Rauf, Sakandar; Andrés, Miguel A.; Roubeau, Olivier; Gascón, Ignacio; Serre, Christian; Eddaoudi, Mohamed; Salama, Khaled N. (Nanomaterials, MDPI AG, 2021-01-10) [Article]
    The Langmuir-Blodgett (LB) method is a well-known deposition technique for the fabrication of ordered monolayer and multilayer thin films of nanomaterials onto different substrates that plays a critical role in the development of functional devices for various applications. This paper describes detailed studies about the best coating configuration for nanoparticles of a porous metal-organic framework (MOF) onto both insulating or conductive threads and nylon fiber. We design and fabricate customized polymethylmethacrylate sheets (PMMA) holders to deposit MOF layers onto the threads or fiber using the LB technique. Two different orientations, namely, horizontal and vertical, are used to deposit MIL-96(Al) monolayer films onto five different types of threads and nylon fiber. These studies show that LB film formation strongly depends on deposition orientation and the type of threads or fiber. Among all the samples tested, cotton thread and nylon fiber with vertical deposition show more homogenous monolayer coverage. In the case of conductive threads, the MOF particles tend to aggregate between the conductive thread’s fibers instead of forming a continuous monolayer coating. Our results show a significant contribution in terms of MOF monolayer deposition onto single fiber and threads that will contribute to the fabrication of single fiber or thread-based devices in the future.
  • An efficient and stable solar flow battery enabled by a single-junction GaAs photoelectrode.

    Fu, Hui-Chun; Li, Wenjie; Yang, Ying; Lin, Chun-Ho; Veyssal, Atilla; He, Jr-Hau; Jin, Song (Nature communications, Springer Science and Business Media LLC, 2021-01-09) [Article]
    Converting and storing solar energy and releasing it on demand by using solar flow batteries (SFBs) is a promising way to address the challenge of solar intermittency. Although high solar-to-output electricity efficiencies (SOEE) have been recently demonstrated in SFBs, the complex multi-junction photoelectrodes used are not desirable for practical applications. Here, we report an efficient and stable integrated SFB built with back-illuminated single-junction GaAs photoelectrode with an n-p-n sandwiched design. Rational potential matching simulation and operating condition optimization of this GaAs SFB lead to a record SOEE of 15.4% among single-junction SFB devices. Furthermore, the TiO2 protection layer and robust redox couples in neutral pH electrolyte enable the SFB to achieve stable cycling over 408 h (150 cycles). These results advance the utilization of more practical solar cells with higher photocurrent densities but lower photovoltages for high performance SFBs and pave the way for developing practical and efficient SFBs.
  • Metabolomic and Biochemical Analysis of Two Potato (Solanum tuberosum L.) Cultivars Exposed to In Vitro Osmotic and Salt Stresses.

    Hamooh, Bahget Talat; Sattar, Farooq Abdul; Wellman, Gordon; Mousa, Magdi Ali Ahmed (Plants (Basel, Switzerland), MDPI AG, 2021-01-09) [Article]
    Globally, many crop production areas are threatened by drought and salinity. Potato ($\textit{Solanum tuberosum}$ L.) is susceptible to these challenging environmental conditions. In this study, an in vitro approach was employed to compare the tolerance of potato cultivars 'BARI-401' (red skin) and 'Spunta' (yellow skin). To simulate ionic and osmotic stress, MS media was supplemented with lithium chloride (LiCl 20 mM) and mannitol (150 mM). GC-MS and spectrophotometry techniques were used to determine metabolite accumulation. Other biochemical properties, such as total phenols concentration (TPC), total flavonoids concentration (TFC), antioxidant capacity (DPPH free radical scavenging capacity), polyphenol oxidase (PPO), and peroxidase (POD) activities, were also measured. The two cultivars respond differently to ionic and osmotic stress treatments, with Spunta accumulating more defensive metabolites in response, indicating a higher level of tolerance. While further investigation of the physiological and biochemical responses of these varieties to drought and salinity is required, the approach taken in this paper provides useful information prior to open field evaluation.
  • Generation of iPSC lines (KAUSTi011-A, KAUSTi011-B) from a Saudi patient with epileptic encephalopathy carrying homozygous mutation in the GLP1R gene.

    Alowaysi, Maryam; Astro, Veronica; Fiacco, Elisabetta; AlZahrani, Fatema; Alkuraya, Fowzan S; Adamo, Antonio (Stem cell research, Elsevier BV, 2021-01-09) [Article]
    Glucagon-like peptide-1 receptor (GLP1R) is a seven-transmembrane-spanning helices membrane protein expressed in multiple human tissues including pancreatic islets, lung, brain, heart and central nervous system (CNS). GLP1R agonists are commonly used as antidiabetic drugs, but a neuroprotective function in neurodegenerative disorders is emerging. Here, we established two iPSC lines from a patient harboring a rare homozygous splice site variant in GLP1R (NM_002062.3; c.402 + 3delG). This patient displays severe developmental delay and epileptic encephalopathy. Therefore, the derivation of these iPSC lines constitutes a primary model to study the molecular pathology of GLP1R dysfunction and develop novel therapeutic targets.
  • Chromatin phosphoproteomics unravels a function for AT-hook motif nuclear localized protein AHL13 in PAMP-triggered immunity

    Rayapuram, Naganand; Jarad, Mai; Alhoraibi, Hanna; Bigeard, Jean; Abulfaraj, Aala A.; Volz, Ronny; Mariappan, Kiruthiga; Almeida-Trapp, Marilia; Schlöffel, Maria; Lastrucci, Emmanuelle; Bonhomme, Ludovic; Gust, Andrea A.; Mithöfer, Axel; Arold, Stefan T.; Pflieger, Delphine; Hirt, Heribert (Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, 2021-01-08) [Article]
    In many eukaryotic systems during immune responses, mitogen-activated protein kinases (MAPKs) link cytoplasmic signaling to chromatin events by targeting transcription factors, chromatin remodeling complexes, and the RNA polymerase machinery. So far, knowledge on these events is scarce in plants and no attempts have been made to focus on phosphorylation events of chromatin-associated proteins. Here we carried out chromatin phosphoproteomics upon elicitor-induced activation of Arabidopsis. The events in WT were compared with those in mpk3, mpk4, and mpk6 mutant plants to decipher specific MAPK targets. Our study highlights distinct signaling networks involving MPK3, MPK4, and MPK6 in chromatin organization and modification, as well as in RNA transcription and processing. Among the chromatin targets, we characterized the AT-hook motif containing nuclear localized (AHL) DNA-binding protein AHL13 as a substrate of immune MAPKs. AHL13 knockout mutant plants are compromised in pathogen-associated molecular pattern (PAMP)-induced reactive oxygen species production, expression of defense genes, and PAMP-triggered immunity. Transcriptome analysis revealed that AHL13 regulates key factors of jasmonic acid biosynthesis and signaling and affects immunity toward Pseudomonas syringae and Botrytis cinerea pathogens. Mutational analysis of the phosphorylation sites of AHL13 demonstrated that phosphorylation regulates AHL13 protein stability and thereby its immune functions.
  • Transcriptomic analysis identifies organ-specific metastasis genes and pathways across different primary sites.

    Zhang, Lin; Fan, Ming; Napolitano, Francesco; Gao, Xin; Xu, Ying; Li, Lihua (Journal of translational medicine, Springer Science and Business Media LLC, 2021-01-08) [Article]
    BackgroundMetastasis is the most devastating stage of cancer progression and often shows a preference for specific organs.MethodsTo reveal the mechanisms underlying organ-specific metastasis, we systematically analyzed gene expression profiles for three common metastasis sites across all available primary origins. A rank-based method was used to detect differentially expressed genes between metastatic tumor tissues and corresponding control tissues. For each metastasis site, the common differentially expressed genes across all primary origins were identified as organ-specific metastasis genes.ResultsPathways enriched by these genes reveal an interplay between the molecular characteristics of the cancer cells and those of the target organ. Specifically, the neuroactive ligand-receptor interaction pathway and HIF-1 signaling pathway were found to have prominent roles in adapting to the target organ environment in brain and liver metastases, respectively. Finally, the identified organ-specific metastasis genes and pathways were validated using a primary breast tumor dataset. Survival and cluster analysis showed that organ-specific metastasis genes and pathways tended to be expressed uniquely by a subgroup of patients having metastasis to the target organ, and were associated with the clinical outcome.ConclusionsElucidating the genes and pathways underlying organ-specific metastasis may help to identify drug targets and develop treatment strategies to benefit patients.
  • Elucidating the Role of Virulence Traits in the Survival of Pathogenic E. coli PI-7 Following Disinfection

    Sivakumar, Krishnakumar; Lehmann, Robert; Rachmadi, Andri Taruna; Augsburger, Nicolas; Zaouri, Noor A.; Tegner, Jesper; Hong, Pei-Ying (Frontiers in bioengineering and biotechnology, Frontiers Media SA, 2021-01-08) [Article]
    Reuse and discharge of treated wastewater can result in dissemination of microorganisms into the environment. Deployment of disinfection strategies is typically proposed as a last stage remediation effort to further inactivate viable microorganisms. In this study, we hypothesize that virulence traits, including biofilm formation, motility, siderophore, and curli production along with the capability to internalize into mammalian cells play a role in survival against disinfectants. Pathogenic E. coli PI-7 strain was used as a model bacterium that was exposed to diverse disinfection strategies such as chlorination, UV and solar irradiation. To this end, we used a random transposon mutagenesis library screening approach to generate 14 mutants that exhibited varying levels of virulence traits. In these 14 isolated mutants, we observed that an increase in virulence traits such as biofilm formation, motility, curli production, and internalization capability, increased the inactivation half-lives of mutants compared to wild-type E. coli PI-7. In addition, oxidative stress response and EPS production contributed to lengthening the lag phase duration (defined as the time required for exposure to disinfectant prior to decay). However, traits related to siderophore production did not help with survival against the tested disinfection strategies. Taken together, the findings suggested that selected virulence traits facilitate survival of pathogenic E. coli PI-7, which in turn could account for the selective enrichment of pathogens over the nonpathogenic ones after wastewater treatment. Further, the study also reflected on the effectiveness of UV as a more viable disinfection strategy for inactivation of pathogens.
  • Strong enhancement of Penning ionisation in cold Rydberg gases II: Tom and Jerry pairs for alkali-metal atoms

    Zalam, Alaa Abo; Bruvelis, M.; Miculis, Kaspars; Beterov, Ilya; Bezuglov, Nikolai N.; Ekers, Aigars; Fuso, Francesco (Journal of Physics B: Atomic, Molecular and Optical Physics, IOP Publishing, 2021-01-08) [Article]
    Penning ionisation (PI) processes involving pairs of Rydberg alkali-metal atoms, excited to different quantum states and experiencing dipole-dipole interactions, have a wide range of important properties in atomic physics. Within the framework of the semi-classical approximation, we have used both numerical and analytical approaches to examine the Penning autoionisation width dependence on the state quantum numbers in a quasi-molecule formed by the interacting partner atoms. We described the characteristics of optimal quantum numbers that lead to enhanced PI widths for the interacting Rydberg atom pairs of all alkali-metal atoms. The excited states of atoms in these pairs are asymmetric, resulting in a large atomic shell size difference: inspired by [1], we call such pair "Tom" and "Jerry" (for "big" and "small"). Compared to symmetric pairs, the optimal asymmetric pairs display a significant (by several orders of magnitude) increase in the PI rate. This property makes PI a relevant source for producing charged particles in cold Rydberg systems that spontaneously evolve into cold plasma. Contrary to hydrogen atoms examined in [1], the difference of quantum defects in alkali-metal atoms results in a strong Penning width dependence on the orbital quantum numbers l of the quasi-molecule. In particular, alkali-metal atoms exhibit two PI channels associated with bound-bound optical transitions showing ∆l = ±1 - individual and closely spaced (doublet-like) configurations of optimal pairs. Furthermore, we demonstrate that the presence of Förster resonances can lead to a notable (up to 5 times) increase of the PI efficiency.
  • Molecular basis for the adaptive evolution of environment sensing by H-NS proteins

    Zhao, Xiaochuan; Shahul Hameed, Umar Farook; Kharchenko, Vladlena; Liao, Chenyi; Huser, Franceline; Remington, Jacob M; Radhakrishnan, Anand K; Jaremko, Mariusz; Jaremko, Lukasz; Arold, Stefan T.; Li, Jianing (eLife, eLife Sciences Publications, Ltd, 2021-01-07) [Article]
    The DNA-binding protein H-NS is a pleiotropic gene regulator in gram-negative bacteria. Through its capacity to sense temperature and other environmental factors, H-NS allows pathogens like Salmonella to adapt their gene expression to their presence inside or outside warm-blooded hosts. To investigate how this sensing mechanism may have evolved to fit different bacterial lifestyles, we compared H-NS orthologs from bacteria that infect humans, plants, and insects, and from bacteria that live on a deep-sea hypothermal vent. The combination of biophysical characterization, high-resolution proton-less NMR spectroscopy and molecular simulations revealed, at an atomistic level, how the same general mechanism was adapted to specific habitats and lifestyles. In particular, we demonstrate how environment-sensing characteristics arise from specifically positioned intra- or intermolecular electrostatic interactions. Our integrative approach clarified the exact modus operandi for H-NS–mediated environmental sensing and suggests that this sensing mechanism resulted from the exaptation of an ancestral protein feature.
  • Chain Conformation Control of Fluorene-Benzothiadiazole Copolymer Light-Emitting Diode Efficiency and Lifetime

    Wang, Bingjun; Ye, Hao; Riede, Moritz; Bradley, Donal (ACS Applied Materials & Interfaces, American Chemical Society (ACS), 2021-01-07) [Article]
    The β-phase, in which the intermonomer torsion angle of a fraction of chain segments approaches ∼180°, is an intriguing conformational microstructure of the widely studied light-emitting polymer poly(9,9-dioctylfluorene) (PFO). Its generation can in turn be used to significantly improve the performance of PFO emission-layer-based light-emitting diodes (LEDs). Here, we report the generation of β-phase chain segments in a copolymer, 90F8:10BT, containing 90% 9,9-dioctylfluorene (F8) and 10% 2,1,3-benzothiadiazole (BT) units and show that significant improvements in performance also ensue for LEDs with β-phase 90F8:10BT emission layers, generalizing the earlier PFO results. The β-phase was induced by both solvent vapor annealing and dipping copolymer thin films into a solvent/nonsolvent mixture. Subsequent absorption spectra show the characteristic fluorene β-phase peak at ∼435 nm, but luminescence spectra (∼530 nm peak) and quantum yields barely change, with the emission arising following efficient energy transfer to the lowest-lying excited states localized in the vicinity of the BT units. For ∼5% β-phase chain segment fraction relative to 0% β-phase, the LED luminance at 10 V increased by ∼25% to 5940 cd m<sup>-2</sup>, the maximum external quantum efficiency by ∼61 to 1.91%, and the operational stability from 64% luminance retention after 20 h of operation to 90%. Detailed studies addressing the underlying device physics identify a reduced hole injection barrier, higher hole mobility, correspondingly more balanced electron and hole charge transport, and decreased carrier trapping as the dominant factors. These results confirm the effectiveness of chain conformation control for fluorene-based homo- and copolymer device optimization.
  • Dark Self-Healing Mediated Negative Photoconductivity of Lead-Free Cs3Bi2Cl9 Perovskite Single Crystal

    Tailor, Naveen Kumar; Maity, Partha; Saidaminov, Makhsud; Pradhan, Narayan; Satapathi, Soumitra (arXiv, 2021-01-07) [Preprint]
    Halide perovskites are recently emerged as one of the frontline optoelectronic materials for device applications and have been extensively studied in past few years. Among these while, lead-based materials were most widely explored, investigation of optical properties of lead-free perovskites is limited. Being optically active, these materials were expected to show light-induced enhanced photoconductivity and the same was reported for lead halide perovskite single crystals. However, on contrary, herein, light-induced degradation of bismuth halide perovskite Cs3Bi2Cl9 single crystals is reported which was evidenced by negative photoconductivity with slow recovery. The femtosecond transient reflectance (fs-TR) spectroscopy studies further revealed these electronic transport properties were due to the formation of light-activated metastable trap states within the perovskite crystal. The figure of merits of Cs3Bi2Cl9 single-crystal detectors such as responsivity (17 mA/W), detectivity (6.23 X 10power 11 Jones) and the ratio of current in dark to light (~7160) was calculated and it is found that they are comparable or higher to reported perovskite single crystals based positive photodetectors. This observation for lead-free perovskite single crystals which were optically active but showed retroactive photocurrent on irradiation remained unique for such materials.
  • Landslide size matters: a new spatial predictive paradigm

    Lombardo, Luigi; Tanyas, Hakan; Huser, Raphaël; Guzzetti, Fausto; Castro-Camilo, Daniela (California Digital Library (CDL), 2021-01-07) [Preprint]
    The standard definition of landslide hazard requires the estimation of where, when (or how frequently) and how large a given landslide event may be. The geomorphological community involved in statistical models has addressed the component pertaining to how large a landslide event may be by introducing the concept of landslide-event magnitude scale. This scale, which depends on the planimetric area of the given population of landslides, in analogy to the earthquake magnitude, has been expressed with a single value per landslide event. As a result, the geographic or spatially-distributed estimation of how large a population of landslide may be when considered at the slope scale, has been disregarded in statistically-based landslide hazard studies. Conversely, the estimation of the landslide extent has been commonly part of physically-based applications, though their implementation is often limited to very small regions.
  • Tractable Bayes of Skew-Elliptical Link Models for Correlated Binary Data

    Zhang, Zhongwei; Arellano-Valle, Reinaldo B.; Genton, Marc G.; Huser, Raphaël (arXiv, 2021-01-06) [Preprint]
    Correlated binary response data with covariates are ubiquitous in longitudinal or spatial studies. Among the existing statistical models the most well-known one for this type of data is the multivariate probit model, which uses a Gaussian link to model dependence at the latent level. However, a symmetric link may not be appropriate if the data are highly imbalanced. Here, we propose a multivariate skew-elliptical link model for correlated binary responses, which includes the multivariate probit model as a special case. Furthermore, we perform Bayesian inference for this new model and prove that the regression coefficients have a closed-form unified skew-elliptical posterior. The new methodology is illustrated by application to COVID-19 pandemic data from three different counties of the state of California, USA. By jointly modeling extreme spikes in weekly new cases, our results show that the spatial dependence cannot be neglected. Furthermore, the results also show that the skewed latent structure of our proposed model improves the flexibility of the multivariate probit model and provides better fit to our highly imbalanced dataset.
  • Ion-exchange doped polymers at the degenerate limit: what limits conductivity at 100% doping efficiency?

    Jacobs, Ian E.; D'Avino, Gabriele; Lin, Yue; Lemaur, Vincent; Huang, Yuxuan; Ren, Xinglong; Simatos, Dimitrios; Wood, William; Chen, Chen; Harrelson, Thomas; Mustafa, Tarig; O'Keefe, Christopher A.; Spalek, Leszek; Tjhe, Dion; Statz, Martin; Lai, Lianglun; Finn, Peter A.; Neal, William G.; Strzalka, Joseph; Nielsen, Christian B.; Lee, Jin-Kyun; Barlow, Stephen; Marder, Seth R.; McCulloch, Iain; Fratini, Simone; Beljonne, David; Sirringhaus, Henning (arXiv, 2021-01-05) [Preprint]
    Doping of semiconducting polymers has seen a surge in research interest driven by emerging applications in sensing, bioelectronics and thermoelectrics. A recent breakthrough was a doping technique based on ion-exchange, which separates the redox and charge compensation steps of the doping process. The improved microstructural control this process allows enables us for the first time to systematically address a longstanding but still poorly understood question: what limits the electrical conductivity at high doping levels? Is it the formation of charge carrier traps in the Coulomb potentials of the counterions, or is it the structural disorder in the polymer lattice? Here, we apply ion-exchange doping to several classes of high mobility conjugated polymers and identify experimental conditions that achieve near 100% doping efficiency under degenerate conditions with nearly 1 charge per monomer. We demonstrate very high conductivities up to 1200 S/cm in semicrystalline polymer systems, and show that in this regime conductivity is poorly correlated with ionic size, but strongly correlated with paracrystalline disorder. This observation, backed by a detailed electronic structure model that incorporates ion-hole and hole-hole interactions and a carefully parameterized model of disorder, indicates that trapping by dopant ions is negligible, and that maximizing crystalline order is critical to improving conductivity.

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