Recent Submissions

  • Topochemical Synthesis of Ca3CrN3H Involving a Rotational Structural Transformation for Catalytic Ammonia Synthesis

    Cao, Yu; Kirsanova, Maria; Ochi, Masayuki; Almaksoud, Walid; Zhu, Tong; Rai, Rohit Kumar; Gao, Shenghan; Tsumori, Tatsuya; Kobayashi, Shintaro; Kawaguchi, Shogo; Abou-Hamad, Edy; Kuroki, Kazuhiko; Tassel, Cédric; Abakumov, Artem; Kobayashi, Yoji; Kageyama, Hiroshi (Angewandte Chemie (International ed. in English), Wiley, 2022-08-05) [Article]
    Topochemical reactions have led to great progress in the discovery of new metastable compounds with novel chemical and physical properties. With these reactions, the overall crystal structure of the host material is generally maintained. Here we report a topochemical synthesis of a hexagonal nitride hydride, h-Ca3CrN3H, by heating an orthorhombic nitride, o-Ca3CrN3, under hydrogen at 673 K, accompanied by a rotational structural transformation. The hydrogen intercalation modifies the Ca-N rock-salt-like atomic packing in o-Ca3CrN3 to a face-sharing octahedral chain in h-Ca3CrN3H, mimicking a 'hinged tessellation' movement. In addition, the h-Ca3CrN3H exhibited stable ammonia synthesis activity when used as a catalyst.
  • The Gardenia Carotenoid Cleavage Dioxygenase 4a is an efficient tool for biotechnological production of crocins in green and non-green plant tissues

    Zheng, Xiongjie; Mi, Jianing; Balakrishna, Aparna; Liew, Kit Xi; Ablazov, Abdugaffor; Sougrat, Rachid; Al-Babili, Salim (Plant Biotechnology Journal, Wiley, 2022-07-29) [Article]
    Crocins are beneficial antioxidants and potential chemotherapeutics that give raise, together with picrocrocin, to the color and taste of saffron, the most expensive spice, respectively. Crocins are formed from crocetin dialdehyde that is produced in Crocus sativus from zeaxanthin by the Carotenoid Cleavage Dioxygenase 2L (CsCCD2L), while GjCCD4a from Gardenia jasminoides, another major source of crocins, converted different carotenoids, including zeaxanthin, into crocetin dialdehyde in bacterio. To establish a biotechnological platform for sustainable production of crocins, we investigated the enzymatic activity of GjCCD4a, in comparison to CsCCD2L, in citrus callus engineered by Agrobacterium-mediated super-transformation of multi genes and in transiently transformed Nicotiana benthamiana leaves. We demonstrate that co-expression of GjCCD4a with phytoene synthase and β-carotene hydroxylase genes is an optimal combination for heterologous production of crocetin, crocins and picrocrocin in citrus callus. By profiling apocarotenoids and using in vitro assays, we show that GjCCD4a cleaved β-carotene, in planta, and produced crocetin dialdehyde via C30 β-apocarotenoid intermediate. GjCCD4a also cleaved C27 β-apocarotenoids, providing a new route for C17-dialdehyde biosynthesis. Callus lines overexpressing GjCCD4a contained higher number of plastoglobuli in chromoplast-like plastids and increased contents in phytoene, C17:0 fatty acid (FA), and C18:1 cis-9 and C22:0 FA esters. GjCCD4a showed a wider substrate specificity and higher efficiency in Nicotiana leaves, leading to the accumulation of up to 1.6 mg/g dry weight crocins. In summary, we established a system for investigating CCD enzymatic activity in planta and an efficient biotechnological platform for crocins production in green and non-green crop tissues/organs.
  • Asymmetric pore windows in MOF membranes for natural gas valorization

    Zhou, Sheng; Shekhah, Osama; Ramírez, Adrian; Lyu, Pengbo; Abou-Hamad, Edy; Jia, Jiangtao; Li, Jiantang; Bhatt, Prashant; Huang, Zhiyuan; Jiang, Hao; Jin, Tian; Maurin, Guillaume; Gascon, Jorge; Eddaoudi, Mohamed (Nature, Springer Science and Business Media LLC, 2022-06-22) [Article]
    To use natural gas as a feedstock alternative to coal and oil, its main constituent, methane, needs to be isolated with high purity1. In particular, nitrogen dilutes the heating value of natural gas and is, therefore, of prime importance for removal2. However, the inertness of nitrogen and its similarities to methane in terms of kinetic size, polarizability and boiling point pose particular challenges for the development of energy-efficient nitrogen-removing processes3. Here we report a mixed-linker metal–organic framework (MOF) membrane based on fumarate (fum) and mesaconate (mes) linkers, Zr-fum67-mes33-fcu-MOF, with a pore aperture shape specific for effective nitrogen removal from natural gas. The deliberate introduction of asymmetry in the parent trefoil-shaped pore aperture induces a shape irregularity, blocking the transport of tetrahedral methane while allowing linear nitrogen to permeate. Zr-fum67-mes33-fcu-MOF membranes exhibit record-high nitrogen/methane selectivity and nitrogen permeance under practical pressures up to 50 bar, removing both carbon dioxide and nitrogen from natural gas. Techno-economic analysis shows that our membranes offer the potential to reduce methane purification costs by about 66% for nitrogen rejection and about 73% for simultaneous removal of carbon dioxide and nitrogen, relative to cryogenic distillation and amine-based carbon dioxide capture.
  • Thicker Ice Improves the Integrity and Angular Distribution of CDC48A Hexamers on Cryo-EM Grids

    Huntington, Brandon; Zhao, Lingyun; Bron, Patrick; Shahul Hameed, Umar F.; Arold, Stefan T.; Qureshi, Bilal M. (Frontiers in Molecular Biosciences, Frontiers Media SA, 2022-06-17) [Article]
    Many cryogenic electron microscopy (cryo-EM) single particle analyses are constrained by the sample preparation step upon which aggregation, dissociation, and/or preferential orientation of particles can be introduced. Here, we report how we solved these problems in the case of CDC48A, a hexameric AAA ATPase from Arabidopsis thaliana. CDC48A hexamers are well preserved under negative staining conditions but disassemble during grid freezing using the classical blotting method. Vitrification of grids using the blot-free Chameleon method preserved the integrity of particles but resulted in their strong preferential orientation. We then used a strategy where we improved in parallel the purification of CDC48A and the conditions for cryo-EM data acquisition. Indeed, we noted that images taken from thicker ice presented an even distribution of intact particles with random orientations, but resulted in a lower image resolution. Consequently, in our case, distribution, orientation, image resolution, and the integrity of particles were tightly correlated with ice thickness. By combining the more homogeneous and stable CDC48A hexamers resulting from our improved purification protocol with an iterative search across different ice thicknesses, we identified an intermediate thickness that retained sufficiently high-resolution structural information while maintaining a complete distribution of particle orientations. Our approach may provide a simple, fast, and generally applicable strategy to record data of sufficient quality under standard laboratory and microscope settings. This method may be of particular value when time and resources are limited.
  • Polyethylene grafted silica nanoparticles via surface-initiated polyhomologation: A novel filler for polyolefin nanocomposite

    Alghamdi, Reem D.; Yudhanto, Arief; Lubineau, Gilles; Abou-Hamad, Edy; Hadjichristidis, Nikos (Polymer, Elsevier BV, 2022-06-17) [Article]
    Silica nanoparticles (SiO2 NPs) were prepared and functionalized with polyethylene (PE@SiO2 NPs) using the surface-initiated polyhomologation (SI-polyhomologation) technique. Polyolefin nanocomposites were fabricated later by melt mixing of different ratios of the as-prepared SiO2 NPs and PE@SiO2 NPs with linear low-density polyethylene (LLDPE) and low-density polyethylene (LDPE) matrices. Firstly, SiO2 NPs were modified with different alkoxysilane ligands, dichloro(divinyl)silane (DCDVS), allyl trimethoxysilane (ATMS), and vinyl triethoxylsilane (VTES). Subsequently, thexylborane, an initiator for SI-polyhomologation, was immobilized to the modified surface of SiO2 NPs through hydroboration reactions. Polyhomologation was then allowed to proceed by adding monomer solution to form polyethylene brushes covalently bonded to the surface of the NPs. Physiochemical characterizations had confirmed the morphology, chemical structure, and thermal stability for each step of modification reactions. LLDPE and LDPE nanocomposites were prepared by extrusion with SiO2 NPs and PE@SiO2 NPs as nanofillers. Finally, tensile tests and morphological SEM-based analyses are presented to discuss the influence of the grafted PE on both the dispersion of the fillers and the mechanical properties of the filler/matrix interphase.
  • Effect of the particle blending-shaping method and silicon carbide crystal phase for Mn-Na-W/SiO2-SiC catalyst in oxidative coupling of methane

    Lezcano, Gontzal; Kulkarni, Shekhar Rajabhau; Velisoju, Vijay Kumar; Musteata, Valentina-Elena; Hita, Idoia; Ramirez, Adrian; Dikhtiarenko, Alla; Gascon, Jorge; Castaño, Pedro (Molecular Catalysis, Elsevier BV, 2022-06-03) [Article]
    Supported Mn-Na-W on silica is a benchmark catalyst for oxidative coupling of methane due to its appropriate ethylene yields. Here we compare eight catalysts with the same active phase (Mn-Na-W) and variable support composition or particle blending-shaping method to evaluate the effect of the support. First, we explore the different preparation methods (impregnation, ball milling, and spray-drying), concluding that spray-drying leads to a promising selective catalyst. Then, we compare different SiC crystal phases (α+β and β), keeping the same composition and shaping method (spray-drying). The catalyst with α+βSiC crystal phase has significantly more activity than the β one in 30 h reaction runs. Finally, we assess the effect of process conditions to improve the yields (15 % at 800°C) of the most promising catalyst: spray-dried and with α+βSiC. The roles of the blending-shaping method and SiC crystal phase are explained by the induced differences in oxidation behavior and active phase distributions.
  • Polytriazole membranes with ultrathin tunable selective layer for crude oil fractionation

    Chisca, Stefan; Musteata, Valentina-Elena; Zhang, Wen; Vasylevskyi, Serhii; Falca, Gheorghe; Abou-Hamad, Edy; Emwas, Abdul-Hamid M.; Altunkaya, Mustafa; Nunes, Suzana Pereira (Science, American Association for the Advancement of Science (AAAS), 2022-06-02) [Article]
    The design of materials and their manufacture into membranes that can handle industrial conditions and separate complex nonaqueous mixtures are challenging. We report a versatile strategy to fabricate polytriazole membranes with 10-nanometer-thin selective layers containing subnanometer channels for the separation of hydrocarbons. The process involves the use of the classical nonsolvent-induced phase separation method and thermal cross-linking. The membrane selectivity can be tuned to the lower end of the typical nanofiltration range (200 to 1000 gram mole−1). The polytriazole membrane can enrich up to 80 to 95% of the hydrocarbon content with less than 10 carbon atoms (140 gram mole−1). These membranes preferentially separate paraffin over aromatic components, making them suitable for integration in hybrid distillation systems for crude oil fractionation.
  • Efficient and simultaneous capture of iodine and methyl iodide achieved by a covalent organic framework

    Xie, Yaqiang; Pan, Tingting; Lei, Qiong; Chen, Cailing; Dong, Xinglong; Yuan, Youyou; Maksoud, Walid Al; Zhao, Long; Cavallo, Luigi; Pinnau, Ingo; Han, Yu (Nature Communications, Springer Science and Business Media LLC, 2022-05-24) [Article]
    Radioactive molecular iodine (I2) and organic iodides, mainly methyl iodide (CH3I), coexist in the off-gas stream of nuclear power plants at low concentrations, whereas few adsorbents can effectively adsorb low-concentration I2 and CH3I simultaneously. Here we demonstrate that the I2 adsorption can occur on various adsorptive sites and be promoted through intermolecular interactions. The CH3I adsorption capacity is positively correlated with the content of strong binding sites but is unrelated to the textural properties of the adsorbent. These insights allow us to design a covalent organic framework to simultaneously capture I2 and CH3I at low concentrations. The developed material, COF-TAPT, combines high crystallinity, a large surface area, and abundant nucleophilic groups and exhibits a record-high static CH3I adsorption capacity (1.53 g·g−1 at 25 °C). In the dynamic mixed-gas adsorption with 150 ppm of I2 and 50 ppm of CH3I, COF-TAPT presents an excellent total iodine capture capacity (1.51 g·g−1), surpassing various benchmark adsorbents. This work deepens the understanding of I2/CH3I adsorption mechanisms, providing guidance for the development of novel adsorbents for related applications.
  • Angle-dependent switching in a magnetic tunnel junction containing a synthetic antiferromagnet

    Chen, Hao; Parks, Brad; Zhang, Qiang; Fang, Bin; Zhang, Xixiang; Majetich, Sara A. (APPLIED PHYSICS LETTERS, AIP Publishing, 2022-05-23) [Article]
    The angle dependence of field-induced switching was investigated in magnetic tunnel junctions with in-plane magnetization and a pinned synthetic antiferromagnet reference layer. The 60 × 90 nm2 elliptical nanopillars had sharp single switches when the field was applied along the major axis of the ellipse, but even with small (20°) deviations, reversal occurred through an intermediate state. The results are interpreted with a model that includes the external applied field and the effective fields due to shape anisotropy and the fringe field of the synthetic antiferromagnet and used to extract the magnetization direction at various points in the magnetoresistance loop. The implications for faster spintronic probabilistic computing devices are discussed.
  • Direct Visualization and Identification of Membrane Voltage-Gated Sodium Channels from Human iPSC-Derived Neurons by Multiple Imaging and Light Enhanced Spectroscopy

    Moretti, Manola; Limongi, Tania; Testi, Claudia; Milanetti, Edoardo; De Angelis, Maria Teresa; Parrotta, Elvira I; Scalise, Stefania; Santamaria, Gianluca; Allione, Marco; Lopatin, Sergei; Torre, Bruno; Zhang, Peng; Marini, Monica; Perozziello, Gerardo; Candeloro, Patrizio; Pirri, Candido Fabrizio; Ruocco, Giancarlo; Cuda, Giovanni; Di Fabrizio, Enzo (Small methods, 2022-05-20) [Article]
    In this study, transmission electron microscopy atomic force microscopy, and surface enhanced Raman spectroscopy are combined through a direct imaging approach, to gather structural and chemical information of complex molecular systems such as ion channels in their original plasma membrane. Customized microfabricated sample holder allows to characterize Nav channels embedded in the original plasma membrane extracted from neuronal cells that are derived from healthy human induced pluripotent stem cells. The identification of the channels is accomplished by using two different approaches, one of them widely used in cryo-EM (the particle analysis method) and the other based on a novel Zernike Polynomial expansion of the images bitmap. This approach allows to carry out a whole series of investigations, one complementary to the other, on the same sample, preserving its state as close as possible to the original membrane configuration.
  • Mo3+ hydride as the common origin of H2 evolution and selective NADH regeneration in molybdenum sulfide electrocatalysts

    Bau, Jeremy; Emwas, Abdul-Hamid M.; Nikolaienko, Pavlo; Aljarb, Areej A.; Tung, Vincent; Rueping, Magnus (Nature Catalysis, Springer Science and Business Media LLC, 2022-05-19) [Article]
    Hydride transfers are key to a number of economically and environmentally important reactions, including H2 evolution and NADH regeneration. The electrochemical generation of hydrides can therefore drive the electrification of chemical reactions to improve their sustainability for a green economy. Catalysts containing molybdenum have recently been recognized as among the most promising non-precious catalysts for H2 evolution, but the mechanism by which molybdenum confers this activity remains debated. Here we show the presence of trapped Mo3+ hydride in amorphous molybdenum sulfide (a-MoSx) during the hydrogen evolution reaction and extend its catalytic role to the selective hydrogenation of the biologically important energy carrier NAD to its active 1,4-NADH form. Furthermore, this reactivity applies to other HER-active molybdenum sulfides. Our results demonstrate a direct role for molybdenum in heterogeneous H2 evolution. This mechanistic finding also reveals that molybdenum sulfides have potential as economic electrocatalysts for NADH regeneration in biocatalysis.
  • Origin of active sites on silica-magnesia catalysts and control of reactive environment in the one-step ethanol-to-butadiene process

    Chung, Sang-Ho; Li, Teng; Shoinkhorova, Tuiana; Ramirez, Adrian; Mukhambetov, Ildar; Abou-Hamad, Edy; Shterk, Genrikh; Telalovic, Selvedin; Dikhtiarenko, Alla; Sirks, Bart; Lavrik, Polina; Tang, Xinqi; Weckhuysen, Bert M.; Bruijnincx, Pieter; Gascon, Jorge; Ruiz-Martinez, Javier (Research Square Platform LLC, 2022-05-18) [Preprint]
    Wet-kneaded silica–magnesia is a benchmark catalyst for the one–step ethanol-to-butadiene Lebedev process. Magnesium silicates, formed during wet-kneading, have been proposed as active sites responsible for butadiene formation, and their catalytic performance has been mainly explained by the variations in the ratio of acid and base sites. While the Lebedev process was developed in the 1930s, However, a detailed insight into how the peculiar, yet essential wet-kneading synthesis leads to the generation, location, and catalytic role of magnesium silicates has not been fully established. Here, we demonstrate that magnesium silicates formation occurs via dissolution of Si and Mg subunits from SiO2 and Mg(OH)2 precursors, initiated by the alkaline pH of the aqueous wet-kneading medium, followed by cross-deposition of the dissolved species on the precursor surfaces. Building on these new insights, two individual model systems (Mg/SiO2 and Si/MgO) were synthesized, representative of the constituents of the wet-kneaded silica–magnesia catalyst, by selective dissolution/deposition induced by pH alteration of the aqueous wet-kneading medium. Using these model catalysts, we demonstrate that the location of the magnesium silicates (i.e., Mg on SiO2 or Si on MgO) governs not only their chemical nature but also the ethanol adsorption configuration, which ultimately cause the catalyst material to be selective mainly for ethylene or butadiene. We demonstrate close proximity at the particle level of the of acid and basic sites is a prerequisite to promote the butadiene formation. The insights gained from the new structure–performance relationships that correlate catalytic activity with types and nature of magnesium silicates can offer new possibilities for the development of next generation Lebedev catalysts.
  • Carbon Nitride Thin Film-Sensitized Graphene Field-Effect Transistor: A Visible-Blind Ultraviolet Photodetector

    Palanisamy, Tamilarasan; Mitra, Somak; Batra, Nitinkumar; Smajic, Jasmin; Emwas, Abdul-Hamid; Roqan, Iman S.; Da Costa, Pedro M. F. J. (Advanced Materials Interfaces, Wiley, 2022-04-27) [Article]
    Ultraviolet (UV) photodetectors often suffer from the lack of spectral selectivity due to strong interference from visible light. In this study, the exceptional electrical properties of graphene and the unique optical properties of carbon nitride thin films (CNTFs) are used to design visible-blind UV photodetectors. First, polycrystalline CNTFs with different thicknesses (12–94 nm) are produced by thermal vapor condensation. Compared to the bulk carbon nitride powder, these films have a considerable sp2 nitrogen deficiency, which is thickness dependent. In addition to showing a wider bandgap than the bulk counterpart, their optical absorption profile (in the ultraviolet–visible range) is unique. Critically, the absorbance falls sharply above 400 nm, making the CNTFs suitable for ultraviolet photodetection. As a result, graphene field-effect transistors (GFETs) sensitized with CNTFs show 103 A W−1 responsivity to UV radiation, a stark contrast to the negligible value obtained in the visible spectrum. The effect of film thickness on the photoresponse is determined, with the thinner CNTF leading to much better device performance. The CNTF/GFET photodetectors are also characterized by their fast response and recovery times, 0.5 and 2.0 s, respectively. These findings pave a simple route for the development of sensitive, visible-blind UV photodetectors.
  • Synthesis and Evaluation of Novel Carboxamides Capable of Causing Centrosome Declustering and Apoptosis in Breast Cancer Cells

    Farrukh, Usama B.; Bilal, Aishah; Zahid, Huda; Iqbal, Maheen; Manzoor, Safia; Firdous, Farhat; Furqan, Muhammad; Azeem, Muhammad; Emwas, Abdul-Hamid M.; Alazmi, Meshari; Gao, Xin; Zaib Saleem, Rahman Shah; Faisal, Amir (ChemistrySelect, Wiley, 2022-04-19) [Article]
    The fragility of cancer cells at the time of mitosis has served as an important target for the development of many successful chemotherapeutic agents. Many cancers cells have supernumerary centrosomes that they cluster during mitosis to form bipolar spindles. Inhibition of centrosome clustering in these cells results in multipolar spindle formation and apoptotic cell death, providing an opportunity to selectively target a subset of cancers with centrosome amplification. In the current work, we report synthesis of 29 novel tethered biaryls and biological evaluation of their ability to inhibit centrosome clustering in breast cancer cells (BT-549). We have identified N-benzhydryl-5-nitrofuran-2-carboxamide (5 h) as a centrosome declustering compound. 5 h has potent antiproliferative activity in centrosome amplified BT-549 cells with GI50 value of 1.81±0.19 μM (n=2). Treatment of BT-549 cells with 5 h causes centrosome declustering resulting in mitotic arrest due to multipolar spindle formation and misaligned chromosomes which ultimately leads to apoptotic cell death
  • Generation of long-lived charges in organic semiconductor heterojunction nanoparticles for efficient photocatalytic hydrogen evolution

    Kosco, Jan; Gonzalez-Carrero, Soranyel; Howells, Calvyn Travis; Fei, Teng; Dong, Yifan; Sougrat, Rachid; Harrison, George T.; Firdaus, Yuliar; Sheelamanthula, Rajendar; Purushothaman, Balaji; Moruzzi, Floriana; Xu, Weidong; Zhao, Lingyun; Basu, Aniruddha; De Wolf, Stefaan; Anthopoulos, Thomas D.; Durrant, James R.; McCulloch, Iain (Nature Energy, Springer Nature, 2022-03-14) [Article]
    Organic semiconductor photocatalysts for the production of solar fuels are attractive as they can be synthetically tuned to absorb visible light while simultaneously retaining suitable energy levels to drive a range of processes. However, a greater understanding of the photophysics that determines the function of organic semiconductor heterojunction nanoparticles is needed to optimize performance. Here, we show that such materials can intrinsically generate remarkably long-lived reactive charges, enabling them to efficiently drive sacrificial hydrogen evolution. Our optimized hetereojunction photocatalysts comprise the conjugated polymer PM6 matched with Y6 or PCBM electron acceptors, and achieve external quantum efficiencies of 1.0% to 5.0% at 400 to 900 nm and 8.7% to 2.6% at 400 to 700 nm, respectively. Employing transient and operando spectroscopies, we find that the heterojunction structure in these nanoparticles greatly enhances the generation of long-lived charges (millisecond to second timescale) even in the absence of electron/hole scavengers or Pt. Such long-lived reactive charges open potential applications in water-splitting Z-schemes and in driving kinetically slow and technologically desirable oxidations.
  • Hierarchical Nanocapsules of Cu-Doped MoS 2@H-Substituted Graphdiyne for Magnesium Storage

    Zhuo, Sifei; Huang, Gang; Sougrat, Rachid; Guo, Jing; Wei, Nini; Shi, Le; Li, Renyuan; Liang, Hanfeng; Shi, Yusuf; Zhang, Qiuyu; Wang, Peng; Alshareef, Husam N. (ACS Nano, American Chemical Society (ACS), 2022-03-07) [Article]
    Hierarchical nanocomposites, which integrate electroactive materials into carbonaceous species, are significant in addressing the structural stability and electrical conductivity of electrode materials in post-lithium-ion batteries. Herein, a hierarchical nanocapsule that encapsulates Cu-doped MoS2(Cu-MoS2) nanopetals with inner added skeletons in an organic-carbon-rich nanotube of hydrogen-substituted graphdiyne (HsGDY) has been developed for rechargeable magnesium batteries (RMB). Notably, both the incorporation of Cu in MoS2and the generation of the inner added nanoboxes are developed from a dual-template of Cu-cysteine@HsGDY hybrid nanowire; the synthesis involves two morphology/composition evolutions by CuS@HsGDY intermediates both taking place sequentially in one continuous process. These Cu-doped MoS2nanopetals with stress-release skeletons provide abundant active sites for Mg2+storage. The microporous HsGDY enveloped with an extended π-conjugation system offers more effective electron and ion transfer channels. These advantages work together to make this nanocapsule an effective cathode material for RMB with a large reversible capacity and superior rate and cycling performance.
  • Unusual Activity of Rationally Designed Cobalt Phosphide/Oxide Heterostructure Composite for Hydrogen Production in Alkaline Medium

    ALSABBAN, Merfat; Eswaran, Mathan Kumar; Peramaiah, Karthik; Wahyudi, Wandi; Yang, Xiulin; Ramalingam, Vinoth; Hedhili, Mohamed. N.; Miao, Xiaohe; Schwingenschlögl, Udo; Li, Lain-Jong; Tung, Vincent; Huang, Kuo-Wei (ACS Nano, American Chemical Society (ACS), 2022-03-07) [Article]
    Design and development of an efficient, nonprecious catalyst with structural features and functionality necessary for driving the hydrogen evolution reaction (HER) in an alkaline medium remain a formidable challenge. At the root of the functional limitation is the inability to tune the active catalytic sites while overcoming the poor reaction kinetics observed under basic conditions. Herein, we report a facile approach to enable the selective design of an electrochemically efficient cobalt phosphide oxide composite catalyst on carbon cloth (CoP-CoxOy/CC), with good activity and durability toward HER in alkaline medium (η10= -43 mV). Theoretical studies revealed that the redistribution of electrons at laterally dispersed Co phosphide/oxide interfaces gives rise to a synergistic effect in the heterostructured composite, by which various Co oxide phases initiate the dissociation of the alkaline water molecule. Meanwhile, the highly active CoP further facilitates the adsorption-desorption process of water electrolysis, leading to extremely high HER activity.
  • Ultrahigh-flux Nanoporous Graphene Membrane for Sustainable Seawater Desalination Using Low-grade Heat

    Lu, Dongwei; Zhou, Zongyao; Wang, Zhihong; Ho, Duc Tam; Sheng, Guan; Chen, Long; Zhao, Yumeng; Li, Xiang; Cao, Li; Schwingenschlögl, Udo; Ma, Jun; Lai, Zhiping (Advanced Materials, Wiley, 2022-01-06) [Article]
    Membrane distillation has attracted great attention in the development of sustainable desalination and zero-discharge processes because of its possibility to recover 100% water and the potential to integrate with low-grade heat such as solar energy. However, the conventional membrane structures and materials afford limited flux thus obstructing its practical application. Here we report ultrathin nanoporous graphene membranes by selectively forming thin graphene layers on the top edges of highly porous anodic alumina oxide support, which creates short and fast transport pathways for water vapor but not liquid. The process avoids the challenging pore-generation and substrate-transfer processes required to prepare regular graphene membranes. In the direct contact membrane distillation mode under a mild temperature pair of 65°C /25°C, the nanoporous graphene membranes show an average water flux of 421.7 Lm<sup>-2</sup> h<sup>-1</sup> with over 99.8% salt rejection, which is an order of magnitude higher than any reported polymeric membranes. The mechanism for high water flux is revealed by detailed characterizations and theoretical modeling. Outdoor field tests using Red Sea water heated under direct sunlight radiation show that the membranes have an average water flux of 86.3 Lm<sup>-2</sup> h<sup>-1</sup> from 8 am. to 8 pm., showing a great potential for real applications in seawater desalination. This article is protected by copyright. All rights reserved.
  • Investigations of crude-oil emulsions at the micro-to-nano scales

    Ravaux, Florent; Medina, Sandra Constanza; Behzad, Ali Reza; Zafar, Humaira; George, Abraham; Morin, Stephane; Ghaffour, NorEddine; Anjum, Dalaver H. (Fuel, Elsevier BV, 2021-12) [Article]
    The removal of the micro droplets of emulsified water from crude oil causes high cost and energy. In this paper we show that cryo electron microscopy (cryo-EM) imaging of micro and nano emulsions prepared from United Arab Emirate based crude oil provides critical information on their stability. Specifically, the cryoSEM imaging analysis applied to emulsion of murban-2019, and upper zakum-2019 crude-oils allowed determining naturally occurring surfactants in these crude-oils. Moreover, the applied method also turned out to be an efficient way to qualitatively investigate the effect of synthetic surfactant on the stability of the emulsions. The high resolution cryoTEM imaging analysis of emulsions from upper zakum-2019 sample enabled visualizing “bilayer” of naturally occurring surfactants, presumably the asphaltene. The cryoTEM analysis further allowed estimating the volume-fraction of emulsified water in the crude-oil at nanoscales and turned out to be about 1% for the upper zakum-2019 samples.
  • Mitochondrial “dysmorphology” in variant classification

    Shamseldin, Hanan E.; Alhashem, Amal; Tabarki, Brahim; Abdulwahab, Firdous; Hashem, Mais; Sougrat, Rachid; Alkuraya, Fowzan S. (Human Genetics, Springer Science and Business Media LLC, 2021-11-08) [Article]
    Mitochondrial disorders are challenging to diagnose. Exome sequencing has greatly enhanced the diagnostic precision of these disorders although interpreting variants of uncertain significance (VUS) remains a formidable obstacle. Whether specific mitochondrial morphological changes can aid in the classification of these variants is unknown. Here, we describe two families (four patients), each with a VUS in a gene known to affect the morphology of mitochondria through a specific role in the fission–fusion balance. In the first, the missense variant in MFF, encoding a fission factor, was associated with impaired fission giving rise to a characteristically over-tubular appearance of mitochondria. In the second, the missense variant in DNAJA3, which has no listed OMIM phenotype, was associated with fragmented appearance of mitochondria consistent with its published deficiency states. In both instances, the highly specific phenotypes allowed us to upgrade the classification of the variants. Our results suggest that, in select cases, mitochondrial “dysmorphology” can be helpful in interpreting variants to reach a molecular diagnosis.

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