Now showing items 1-20 of 20918

    • An examination of introgression and incomplete lineage sorting among three closely related species of chocolate-dipped damselfish (genus: Chromis )

      He, Song; Robitzch, Vanessa; Hobbs, Jean-Paul A.; Travers, Michael J.; Lozano-Cortés, Diego; Berumen, Michael L.; DiBattista, Joseph D. (Ecology and Evolution, Wiley, 2019-04-20) [Article]
      Aim To determine the impact of ecological and environmental histories on the evolution of coral reef damselfishes at two adjacent marine biogeographic suture zones. Location Indo-West Pacific, notably including two suture zones: Socotra and Christmas and Cocos/Keeling Islands. Taxon Chromis dimidiata, Chromis margaritifer, and Chromis fieldi. Methods We utilized a combination of nuclear and mitochondrial genetic markers in addition to visual abundance survey data of these fishes. Results Despite genetic patterns consistent with incomplete lineage sorting and relatively low genetic differentiation among the three studied Chromis species, there is evidence of hybridization between C. margaritifer and C. fieldi at Christmas Island based on molecular and visual identification. Introgression appears to be spreading westwards to other C. fieldi populations based on COI haplotype comparison. Moreover, the genetic distance between C. margaritifer and C. fieldi suggests that Pleistocene sea-level fluctuations may have contributed to allopatric divergence and secondary contact between these two closely related species. Main conclusions Our study highlights that evolutionary processes in coral reef fishes operate differently between suture zones, possibly due to different ecological and environmental predispositions regulating secondary contact of sister species. While secondary contact likely led to hybridization and introgression at Christmas and Cocos/Keeling Islands, none of those processes seem present at Socotra for the chocolate-dipped damselfish. This difference is likely due to an environmental barrier caused by hydrodynamic regimes in the Gulf of Aden.
    • Energy costs of salt tolerance in crop plants

      Munns, Rana; Day, David A; Fricke, Wieland; Watt, Michelle; Arsova, Borjana; Barkla, Bronwyn J; Bose, Jayakumar; Byrt, Caitlin S; Chen, Zhong-Hua; Foster, Kylie J; Gilliham, Matthew; Henderson, Sam W; Jenkins, Colin L D; Kronzucker, Herbert J; Miklavcic, Stanley J; Plett, Darren; Roy, Stuart J; Shabala, Sergey; Shelden, Megan C; Soole, Kathleen L; Taylor, Nicolas L; Tester, Mark A.; Wege, Stefanie; Wegner, Lars H; Tyerman, Stephen D (New Phytologist, Wiley, 2019-04-20) [Article]
      Agriculture is expanding into regions that are affected by salinity. This review considers energy costs of salinity tolerance in crop plants and provides a framework for a quantitative assessment of costs. Different sources of energy, and modifications of root system architecture that would maximise water versus ion uptake are addressed. Energy requirements for transport of NaCl to leaf vacuoles for osmotic adjustment could be small if there are no substantial leaks back across plasma membrane and tonoplast in root and leaf. The coupling ratio of H+ -ATPase is also a critical component. One proposed leak, that of Na+ influx across the plasma membrane through certain aquaporin channels, might be coupled to water flow, thus conserving energy. For the tonoplast, control of two types of cation channels is required for energy efficiency. Transporters controlling the Na+ and Cl- concentrations in mitochondria and chloroplasts are largely unknown and could be a major energy cost. The complexity of the system will require a sophisticated modelling approach to identify critical transporters, apoplastic barriers and root structures. This modelling approach will inform experimentation and allow a quantitative assessment of the energy costs of salt tolerance to guide breeding and engineering of molecular components. This article is protected by copyright. All rights reserved.
    • Performance investigation of MEMSYS vacuum membrane distillation system in single effect and multi-effect mode

      Burhan, Muhammad; Shahzad, Muhammad Wakil; Ybyraiymkul, Doskhan; Oh, Seung Jin; Ghaffour, NorEddine; Ng, Kim Choon (Sustainable Energy Technologies and Assessments, Elsevier BV, 2019-04-19) [Article]
      With increase in fresh water demand and lack of fresh water resources, the current water scarcity can only be solved with seawater desalination. However, due to high dependence of current desalination technologies on fossil fuels, especially in GCC countries where the share of thermal desalination systems is dominating, the environmental sustainability is at risk. Despite high operational and maintenance cost, electricity operated membrane based reverse osmosis (RO) system provides simple configuration with less capital cost. Therefore, for future sustainable desalination, more innovative and energy efficient methods have to be sought out which will not only have the low operational cost of the thermal desalination systems but they can also have simple design and fabrication cost of membrane based systems. Vacuum membrane distillation (VMD) is a thermal distillation technique that works on the vapor pressure across the hydrophobic membrane. With the introduction of heat recovery scheme within the VMD modules in form of the multi-effect VMD operation, a detailed performance analysis of the VMD system is presented in this study under different operating conditions. The performance of system is investigated on components level with comparison between single effect and multi-effect operation.
    • Polarization Image Dataset

      Fu, Qiang; Qiu, Simeng; Wang, Congli; Heidrich, Wolfgang (2019-04-18) [Dataset]
    • An overview of e-resources acquisitions in KAUST

      Kabli, Ola A. (2019-04-18)
      Within a changing and flexible environment and in a digitally born library, this presentation will cover the library electronic resources acquisition lifecycle from receiving the request from the subject specialists until the access is provided going through acquiring quotations, invoices, getting the LA signed, and get it paid by finance in addition to the role we play to serve other university departments. It will address the best practices as well as the challenges throughout the process and how to keep a smooth workflow and highlight on the value of communication between library staff internally and with other departments to meet the patrons needs accurately and promptly. A glance on the number of e- resources, types and number of publishers we’re dealing with will be covered too. With a ‘dealing directly with publishers’ policy we of course are working collaboratively with them to maintain the productive professional relationship. It will also focus on the systems we use and the record keeping for all renewal information including license agreements and make it accessible to stakeholders. The effort of improving and enhancing e- resources acquisition is continuing. With a good future plan and a strategy, future can always be better.
    • Acquisitions process, previously & currently

      Alsaada, Riyam (2019-04-18)
      The library acquisitions - which is called in Princesses Noura University the building and development of information resources- is the department of the central library responsible for the selection and purchase of materials or resources in order to serve the researchers and support the university departments and academic programs. This presentation is going to cover our experience in the acquisition previously and currently.
    • Print Resources Acquisition Process

      Al Qahtani, Ali (2019-04-18)
    • Are the ecological effects of the “worst” marine invasive species linked with scientific and media attention?

      Geraldi, Nathan R; Anton, Andrea; Lovelock, Catherine E; Duarte, Carlos M. (PLOS ONE, Public Library of Science (PLoS), 2019-04-18) [Article]
      Non-native species are a major driver of environmental change. In this study we assessed the ecological impact of the
    • Discovering, Characterizing, and Applying Acyl Homoserine Lactone-Quenching Enzymes to Mitigate Microbe-Associated Problems Under Saline Conditions

      Wang, Tian-Nyu; Guan, Qing-Tian; Pain, Arnab; Kaksonen, Anna H.; Hong, Pei-Ying (Frontiers in Microbiology, Frontiers Media SA, 2019-04-17) [Article]
      Quorum quenching (QQ) is proposed as a new strategy for mitigating microbe-associated problems (e.g., fouling, biocorrosion). However, most QQ agents reported to date have not been evaluated for their quenching efficacies under conditions representative of seawater desalination plants, cooling towers or marine aquaculture. In this study, bacterial strains were isolated from Saudi Arabian coastal environments and screened for acyl homoserine lactone (AHL)-quenching activities. Five AHL quenching bacterial isolates from the genera Pseudoalteromonas, Pontibacillus, and Altererythrobacter exhibited high AHL-quenching activity at a salinity level of 58 g/L and a pH of 7.8 at 50°C. This result demonstrates the potential use of these QQ bacteria in mitigating microbe-associated problems under saline and alkaline conditions at high (>37°C) temperatures. Further characterizations of the QQ efficacies revealed two bacterial isolates, namely, Pseudoalteromonas sp. L11 and Altererythrobacter sp. S1-5, which could possess enzymatic QQ activity. The genome sequences of L11 and S1-5 with a homologous screening against reported AHL quenching genes suggest the existence of four possible QQ coding genes in each strain. Specifically, two novel AHL enzymes, AiiAS1-5 and EstS1-5 from Altererythrobacter sp. S1-5, both contain signal peptides and exhibit QQ activity over a broad range of pH, salinity, and temperature values. In particular, AiiAS1-5 demonstrated activity against a wide spectrum of AHL molecules. When tested against three bacterial species, namely, Aeromonas hydrophila, Pseudomonas aeruginosa, and Vibrio alginolyticus, AiiAS1-5 was able to inhibit the motility of all three species under saline conditions. The biofilm formation associated with P. aeruginosa was also significantly inhibited by AiiAS1-5. AiiAS1-5 also reduced the quorum sensing-mediated virulence traits of A. hydrophila, P. aeruginosa, and V. alginolyticus during the mid and late exponential phases of cell growth. The enzyme did not impose any detrimental effects on cell growth, suggesting a lower potential for the target bacterium to develop resistance over long-term exposure. Overall, this study suggested that some QQ enzymes obtained from the bacteria that inhabit saline environments under high temperatures have potential applications in the mitigation of microbe-associated problems.
    • A Random Forest Machine Learning Approach for the Retrieval of Leaf Chlorophyll Content in Wheat

      Shah, Syed Haleem; Angel, Yoseline; Houborg, Rasmus; Ali, Shawkat; McCabe, Matthew (Remote Sensing, MDPI AG, 2019-04-17) [Article]
      Developing rapid and non-destructive methods for chlorophyll estimation over large spatial areas is a topic of much interest, as it would provide an indirect measure of plant photosynthetic response, be useful in monitoring soil nitrogen content, and offer the capacity to assess vegetation structural and functional dynamics. Traditional methods of direct tissue analysis or the use of handheld meters, are not able to capture chlorophyll variability at anything beyond point scales, so are not particularly useful for informing decisions on plant health and status at the field scale. Examining the spectral response of plants via remote sensing has shown much promise as a means to capture variations in vegetation properties, while offering a non-destructive and scalable approach to monitoring. However, determining the optimum combination of spectra or spectral indices to inform plant response remains an active area of investigation. Here, we explore the use of a machine learning approach to enhance the estimation of leaf chlorophyll (Chlt), defined as the sum of chlorophyll a and b, from spectral reflectance data. Using an ASD FieldSpec 4 Hi-Res spectroradiometer, 2700 individual leaf hyperspectral reflectance measurements were acquired from wheat plants grown across a gradient of soil salinity and nutrient levels in a greenhouse experiment. The extractable Chlt was determined from laboratory analysis of 270 collocated samples, each composed of three leaf discs. A random forest regression algorithm was trained against these data, with input predictors based upon (1) reflectance values from 2102 bands across the 400–2500 nm spectral range; and (2) 45 established vegetation indices. As a benchmark, a standard univariate regression analysis was performed to model the relationship between measured Chlt and the selected vegetation indices. Results show that the root mean square error (RMSE) was significantly reduced when using the machine learning approach compared to standard linear regression. When exploiting the entire spectral range of individual bands as input variables, the random forest estimated Chlt with an RMSE of 5.49 µg·cm−2 and an R2 of 0.89. Model accuracy was improved when using vegetation indices as input variables, producing an RMSE ranging from 3.62 to 3.91 µg·cm−2, depending on the particular combination of indices selected. In further analysis, input predictors were ranked according to their importance level, and a step-wise reduction in the number of input features (from 45 down to 7) was performed. Implementing this resulted in no significant effect on the RMSE, and showed that much the same prediction accuracy could be obtained by a smaller subset of indices. Importantly, the random forest regression approach identified many important variables that were not good predictors according to their linear regression statistics. Overall, the research illustrates the promise in using established vegetation indices as input variables in a machine learning approach for the enhanced estimation of Chlt from hyperspectral data.
    • A tutorial on laser-based lighting and visible light communications: device and technology [Invited]

      Yujian Guo, Yujian Guo; Omar Alkhazragi, Omar Alkhazragi; Chun Hong Kang, Chun Hong Kang; Chao Shen, Chao Shen; Yuan Mao, Yuan Mao; Xiaobin Sun, Xiaobin Sun; Tien Khee Ng, Tien Khee Ng; Boon S. Ooi, Boon S. Ooi (Chinese Optics Letters, Shanghai Institute of Optics and Fine Mechanics, 2019-04-17) [Article]
      This tutorial focuses on devices and technologies that are part of laser-based visible light communication (VLC) systems. Laser-based VLC systems have advantages over their light-emitting-diode-based counterparts, including having high transmission speed and long transmission distance. We summarize terminologies related to laser-based solid-state lighting and VLC, and further review the advances in device design and performance. The high-speed modulation characteristics of laser diodes and superluminescent diodes and the on-chip integration of optoelectronic components in the visible color regime, such as the high-speed integrated photodetector, are introduced. The modulation technology for laser-based white light communication systems and the challenges for future development are then discussed.
    • Remotely sensing harmful algal blooms in the Red Sea

      Gokul, Elamurugu Alias; Raitsos, Dionysios E.; Gittings, John; Alkawri, Abdulsalam; Hoteit, Ibrahim (PLOS ONE, Public Library of Science (PLoS), 2019-04-16) [Article]
      Harmful Algal Blooms (HABs) are of global concern, as their presence is often associated with socio-economic and environmental issues including impacts on public health, aquaculture and fisheries. Therefore, monitoring the occurrence and succession of HABs is fundamental for managing coastal regions around the world. Yet, due to the lack of adequate in situ measurements, the detection of HABs in coastal marine ecosystems remains challenging. Sensors on-board satellite platforms have sampled the Earth synoptically for decades, offering an alternative, cost-effective approach to routinely detect and monitor phytoplankton. The Red Sea, a large marine ecosystem characterised by extensive coral reefs, high levels of biodiversity and endemism, and a growing aquaculture industry, is one such region where knowledge of HABs is limited. Here, using high-resolution satellite remote sensing observations (1km, MODIS-Aqua) and a second-order derivative approach, in conjunction with available in situ datasets, we investigate for the first time the capability of a remote sensing model to detect and monitor HABs in the Red Sea. The model is able to successfully detect and generate maps of HABs associated with different phytoplankton functional types, matching concurrent in situ data remarkably well. We also acknowledge the limitations of using a remote-sensing based approach and show that regardless of a HAB's spatial coverage, the model is only capable of detecting the presence of a HAB when the Chl-a concentrations exceed a minimum value of ~ 1 mg m-3. Despite the difficulties in detecting HABs at lower concentrations, and identifying species toxicity levels (only possible through in situ measurements), the proposed method has the potential to map the reported spatial distribution of several HAB species over the last two decades. Such information is essential for the regional economy (i.e., aquaculture, fisheries & tourism), and will support the management and sustainability of the Red Sea's coastal economic zone.
    • Bismuth-based Perovskite-Inspired Solar Cells: In situ Diagnostics Reveal Similarities and Differences in the Film Formation of Bismuth- and Lead-based Films

      Tang, Ming-Chun; Barrit, Dounya; Munir, Rahim; Li, Ruipeng; Barbe, Jeremy; Smilgies, Detlef-M.; Del Gobbo, Silvano; Anthopoulos, Thomas D.; Amassian, Aram (Solar RRL, Wiley, 2019-04-16) [Article]
      Organic-inorganic lead-based halide perovskite compounds have recently been utilized in solar cells with power conversion efficiency (PCE) of >23%. However, replacing the lead with less-toxic elements while maintaining high device performance remains a challenge. For this reason, significant effort has been directed toward the development of Pb-free compounds, including bismuth (Bi)-based methylammonium bismuth iodide (MA3 Bi2I9), but such systems continue to severely underperform when compared to the prototypical Pb-based methylammonium lead iodide (MAPbI3) perovskite. For the latter, and other Pb-based systems, it is known that Pb2+ complexes with polar solvents, such as DMSO and DMF, and solution-processed MAPbI3 and PbI2, form intermediate ordered precursor phases that incorporate these solvents into co-crystals during solution processing. Here, we compare and contrast the solidification and growth behaviors of Bi and Pb precursor inks based on the same solvents using multi-probe characterization methods. In both instances, we see evidence of a sol-gel process whereby solvent-metal complexes form and lead to a colloidal solution which solidifies. We show that the Bi-based compound crystallizes directly and rapidly into a textured polycrystalline microstructure from a precursor solution without evolving through intermediate crystalline solvated phases, in contrast to MAPbI3. This solidification process produces isolated crystals and challenges the growth of continuous and crystalline films required for application in solar cells. We reveal that solvent engineering in combination with antisolvent dripping are necessary to address this limitation and enable the formation of continuous polycrystalline films of Pb-free MA3Bi2I9 and functional solar cells. The work provides valuable insights linking the solid-state microstructure of the film and solar cell performance to the ink formulation and the solidification pathway.
    • Dual-Function Electron-Conductive, Hole-Blocking Titanium Nitride Contacts for Efficient Silicon Solar Cells

      Yang, Xinbo; Liu, Wenzhu; de Bastiani, Michele; Allen, Thomas; Kang, Jingxuan; Xu, Hang; Aydin, Erkan; Xu, Lujia; Bi, Qunyu; Dang, Hoang; AlHabshi, Esra; Kotsovos, Konstantinos; AlSaggaf, Ahmed; Gereige, Issam; Wan, Yimao; Peng, Jun; Samundsett, Christian; Cuevas, Andres; De Wolf, Stefaan (Joule, Elsevier BV, 2019-04-16) [Article]
      High-performance passivating contact is a prerequisite for high-efficiency crystalline silicon (c-Si) solar cells. In this work, an electron-conductive, hole-blocking contact based on titanium nitride (TiN) deposited by reactive magnetron sputtering is presented. Quasi-metallic TiN combined with an ultrathin SiO2 passivation layer (SiO2/TiN) is demonstrated to be an effective electron-selective contact on c-Si, featuring a low-contact resistivity of 16.4 mΩ.cm2 and a tolerable recombination current parameter of ∼500 fA/cm2. By implementing the dual-function SiO2/TiN contact, which acts simultaneously as a surface passivating layer and metal electrode, an efficiency of 20% is achieved by an n-type c-Si solar cell with a simple structure. This work not only demonstrates a way to develop efficient n-type c-Si solar cells with dual-function metal nitride contacts at a low cost but also expands the pool of available carrier transport materials, from metal oxides to metal nitrides, for photovoltaic devices.
    • Metabopolis: scalable network layout for biological pathway diagrams in urban map style

      Wu, Hsiang-Yun; Nöllenburg, Martin; Sousa, Filipa L.; Viola, Ivan (BMC Bioinformatics, Springer Nature, 2019-04-16) [Article]
      Background Biological pathways represent chains of molecular interactions in biological systems that jointly form complex dynamic networks. The network structure changes from the significance of biological experiments and layout algorithms often sacrifice low-level details to maintain high-level information, which complicates the entire image to large biochemical systems such as human metabolic pathways. Results Our work is inspired by concepts from urban planning since we create a visual hierarchy of biological pathways, which is analogous to city blocks and grid-like road networks in an urban area. We automatize the manual drawing process of biologists by first partitioning the map domain into multiple sub-blocks, and then building the corresponding pathways by routing edges schematically, to maintain the global and local context simultaneously. Our system incorporates constrained floor-planning and network-flow algorithms to optimize the layout of sub-blocks and to distribute the edge density along the map domain. We have developed the approach in close collaboration with domain experts and present their feedback on the pathway diagrams based on selected use cases. Conclusions We present a new approach for computing biological pathway maps that untangles visual clutter by decomposing large networks into semantic sub-networks and bundling long edges to create space for presenting relationships systematically.
    • Highly selective chromoionophores for ratiometric Na+ sensing based on an oligoethyleneglycol bridged bithiophene detection unit

      Moser, Maximilian; Thorley, Karl J.; Moruzzi, Floriana; Ponder, James F.; Maria, Iuliana P.; Giovannitti, Alexander; Inal, Sahika; McCulloch, Iain (Journal of Materials Chemistry C, Royal Society of Chemistry (RSC), 2019-04-16) [Article]
      Rapid and efficient measurement of sodium ion concentrations will benefit future studies and healthcare due to the importance of sodium to many biological processes. Ratiometric optical probes, where light absorption wavelengths shift according to ion concentration, can be used as a quick measurement method. In contrast to the currently available UV absorbing probes, we have synthesised a series of sensors which absorb in different regions of the visible spectrum. In addition to measurement by conventional UV-Vis spectroscopy, this also enables analysis of sodium ion concentration from colorimetry, opening the door to faster and cheaper analysis. Finally, the optical properties of the dyes were well reproduced by computational methods, with and without the presence of sodium, enabling acceleration of design of future materials.
    • Structural and Energetic Impact of Non-natural 7-Deaza-8-Azaguanine, 7-Deaza-8-Azaisoguanine and their 7-Substituted Derivatives on H-bonding Pairing with Cytosine and Isocytosine

      Chawla, Mohit; Minenkov, Yury; Vu, Khanh B; Oliva, Romina; Cavallo, Luigi (ChemBioChem, Wiley, 2019-04-15) [Article]
      We theoretically characterized the impact that the 7-deaza-8-azaguanine (DAG) and 7-deaza-8-azaisoguanine (DAiG) modifications have on the geometry and stability of the G:C Watson-Crick (cWW) base pair and of the G:iC and iG:C reverse Watson-Crick (tWW) base pairs. In addition, we investigated the effect on the same base pairs of seven C7-substituted DAG and DAiG, some of which have been previously experimentally characterized. Our calculations indicate that all these modifications have a negligible impact on the geometry of the above base pairs, and that the modification of the heterocycle skeleton has small impact on the base pair interaction energies. Instead, base pair interaction energies are dependent on the nature of the C7 substituent. For the 7-substituted DAG-C cWW systems we found a linear correlation between the base pair interaction energy and the Hammett constant of the 7-substituent, with higher interaction energies corresponding to more electron-withdrawing substituents. Therefore, the explored modifications are expected to be accommodated in both parallel and antiparallel nucleic acid duplexes without perturbing their geometry, while the strength of a base pair (and duplex) featuring a DAG modification can in principle be tuned by incorporating different substituents at the C7 position.
    • Extra-pair mating in a socially monogamous and paternal mouthbrooding cardinalfish

      Rueger, Theresa; Harrison, Hugo B; Gardiner, Naomi M; Berumen, Michael L.; Jones, Geoffrey P (Molecular Ecology, Wiley, 2019-04-15) [Article]
      Many vertebrates form monogamous pairs to mate and care for their offspring. However, genetic tools have increasingly shown that many offspring arise from matings outside of the monogamous pair bond. Social monogamy is relatively common in coral reef fishes, but there have been relatively few studies that have confirmed monogamy or extra-pair reproduction, either for males or females. Here long-term observations and genetic tools were applied to examine the parentage of embryos in a paternally mouthbrooding cardinalfish, Sphaeramia nematoptera. Paternal care in fishes, such as mouth brooding, is thought to be associated with a high degree of confidence in paternity. Two-years of observations confirmed that S. nematoptera form long-term pair bonds within larger groups. However, genetic parentage revealed extra-pair mating by both sexes. Of 105 broods analysed from 64 males, 30.1% were mothered by a female that was not the partner and 11.5% of broods included eggs from two females. Despite the high paternal investment associated with mouthbrooding, 7.6% of broods were fertilised by two males. Extra-pair matings appeared to be opportunistic encounters with individuals from outside the immediate group. We argue that while pair formation contributes to group cohesion, both males and females can maximise lifetime reproductive success by taking advantage of extra-pair mating opportunities. This article is protected by copyright. All rights reserved.
    • Inhibition of autotransporter biogenesis by small molecules

      Steenhuis, Maurice; Abdallah, Abdallah; de Munnik, Sabrina M; Kuhne, Sebastiaan; Sterk, Geert-Jan; van der Berg van Saparoea, Bart; Westerhausen, Sibel; Wagner, Samuel; van der Wel, Nicole N; Wijtmans, Maikel; van Ulsen, Peter; Jong, Wouter S; Luirink, Joen (Molecular Microbiology, Wiley, 2019-04-15) [Article]
      Disarming pathogens by targeting virulence factors is a promising alternative to classic antibiotics. Many virulence factors in Gram-negative bacteria are secreted via the autotransporter (AT) pathway, also known as Type 5 secretion. These factors are secreted with the assistance of two membrane-based protein complexes: Sec and Bam. To identify inhibitors of the AT pathway we used transcriptomics analysis to develop a fluorescence-based high-throughput assay that reports on the stress induced by the model AT hemoglobin protease (Hbp) when its secretion across the outer membrane is inhibited. Screening a library of 1600 fragments yielded the compound VUF15259 that provokes cell envelope stress and secretion inhibition of the ATs Hbp and Antigen-43. VUF15259 also impairs β-barrel folding activity of various outer membrane proteins. Furthermore, we found that mutants that are compromised in outer membrane protein biogenesis are more susceptible to VUF15259. Finally, VUF15259 induces the release of vesicles that appear to assemble in short chains. Taken together, VUF15259 is the first reported compound that inhibits AT secretion and our data are mostly consistent with VUF15259 interfering with the Bam-complex as potential mode of action. The validation of the presented assay incites its use to screen larger compound libraries with drug-like compounds. This article is protected by copyright. All rights reserved.
    • Unprecedented ultralow detection limit of amines using a thiadiazole-functionalized Zr(IV)-based metal-organic framework

      Mallick, Arijit; El-Zohry, Ahmed M.; Shekhah, Osama; Yin, Jun; Jia, Jiangtao; Aggarwal, Himanshu; Emwas, Abdul-Hamid M.; Mohammed, Omar F.; Eddaoudi, Mohamed (Journal of the American Chemical Society, American Chemical Society (ACS), 2019-04-15) [Article]
      A luminescent Zr(IV)-based MOF, with the underlying fcu topology, encompassing a π-conjugated organic ligand with a thiadiazole functionality, exhibits an unprecedented low detection limit of 66 nanomolar (nM) for amines in aqueous solution. Markedly, this ultra-low detection is driven by the hydro-gen bonding interactions between the linker and amines. This observation is fully supported by Density Functional Theory (DFT) calculations which clearly corroborate the suppression of the twisting motion of the thiadiazole core in the presence of amine, reducing significantly the non-radiative recombination pathways and subsequently enhancing the emission intensity. Credibly, nicotine regarded as a harmful chemical and bearing an amine pending group is also detected with high sensitivity, positioning this MOF as a potential sensor for practical environmental applications. This finding not only provides an unprecedented low detection limit, but also serves as a benchmark to understand the sensing mechanism in MOFs.