Recent Submissions

  • Single-Particle Spectroscopy as a Versatile Tool to Explore Lower-Dimensional Structures of Inorganic Perovskites

    Bose, Riya; Zhou, Xiaohe; Guo, Tianle; Yang, Haoze; Yin, Jun; Mishra, Aditya; Slinker, Jason D.; Bakr, Osman; Mohammed, Omar F.; Malko, Anton V. (ACS Energy Letters, American Chemical Society (ACS), 2021-09-27) [Article]
    The remarkable defect-tolerant nature of inorganic cesium halide perovskites, leading to near unity photoluminescence (PL) quantum yield and narrow emission line width across the entire visible spectrum, has provided a tantalizing platform for the development of a plethora of light-emitting applications. Recently, lower-dimensional (2D, 1D, and 0D) perovskites have attracted further attention due to their enhanced thermal, photo, and chemical stability as compared to their three-dimensional (3D) analogues. The combination of external size quantization and internal octahedral organization provides a unique opportunity to study and harness “multi-dimensional” electronic properties engineered on both atomic scale and nanoscale. However, crucial research to understand the elementary charge carrier dynamics in lower-dimensional perovskites lags far behind the enormous effort to incorporate them into optoelectronic devices. In this Perspective, we provide a review of recent developments that focus on studies of the dynamics of excitonic complexes in Cs-based perovskite nanocrystals using single-particle time-resolved PL spectroscopy and photon correlation measurements. Single-photon statistical studies not only offer an unprecedented level of detail to directly assess various recombination pathways, but also provide insights into specifics of the charge carriers' localization. We discuss the underlying physicochemical processes that govern PL emission and draw attention to a number of attributes within this class of the materials, especially lower-dimensional perovskites, that may indicate the common origin of the PL emission as well as provide a route map for the vast unexplored territories where single-particle spectroscopy can be a powerful tool to unravel crucial information.
  • Crystallization and Morphology of Triple Crystalline Polyethylene-b-poly(ethylene oxide)-b-poly(ε-caprolactone) PE-b-PEO-b-PCL Triblock Terpolymers

    Matxinandiarena, Eider; Múgica, Agurtzane; Zubitur, Manuela; Ladelta, Viko; Zapsas, Georgios; Cavallo, Dario; Hadjichristidis, Nikos; Müller, Alejandro J. (Polymers, MDPI AG, 2021-09-16) [Article]
    The morphology and crystallization behavior of two triblock terpolymers of polymethylene, equivalent to polyethylene (PE), poly (ethylene oxide) (PEO), and poly (ε-caprolactone) (PCL) are studied: PE227.1-b-PEO4615.1-b-PCL3210.4 (T1) and PE379.5-b-PEO348.8-b-PCL297.6 (T2) (superscripts give number average molecular weights in kg/mol and subscripts composition in wt %). The three blocks are potentially crystallizable, and the triple crystalline nature of the samples is investigated. Polyhomologation (C1 polymerization), ring-opening polymerization, and catalyst-switch strategies were combined to synthesize the triblock terpolymers. In addition, the corresponding PE-b-PEO diblock copolymers and PE homopolymers were also analyzed. The crystallization sequence of the blocks was determined via three independent but complementary techniques: differential scanning calorimetry (DSC), in situ SAXS/WAXS (small angle X-ray scattering/wide angle X-ray scattering), and polarized light optical microscopy (PLOM). The two terpolymers (T1 and T2) are weakly phase segregated in the melt according to SAXS. DSC and WAXS results demonstrate that in both triblock terpolymers the crystallization process starts with the PE block, continues with the PCL block, and ends with the PEO block. Hence triple crystalline materials are obtained. The crystallization of the PCL and the PEO block is coincident (i.e., it overlaps); however, WAXS and PLOM experiments can identify both transitions. In addition, PLOM shows a spherulitic morphology for the PE homopolymer and the T1 precursor diblock copolymer, while the other systems appear as non-spherulitic or microspherulitic at the last stage of the crystallization process. The complicated crystallization of tricrystalline triblock terpolymers can only be fully grasped when DSC, WAXS, and PLOM experiments are combined. This knowledge is fundamental to tailor the properties of these complex but fascinating materials.
  • Recent Progress on Polymers of Intrinsic Microporosity and Thermally Modified Analogue Materials for Membrane-Based Fluid Separations

    Wang, Yingge; Ghanem, Bader; Ali, Zain; Hazazi, Khalid; Han, Yu; Pinnau, Ingo (Small Structures, Wiley, 2021-09-14) [Article]
    Solution-processable amorphous glassy polymers of intrinsic microporosity (PIMs) are promising microporous organic materials for membrane-based gas and liquid separations due to their high surface area and internal free volume, thermal and chemical stability, and excellent separation performance. This review provides an overview of the most recent developments in the design and transport properties of novel ladder PIM materials, polyimides of intrinsic microporosity (PIM–PIs), functionalized PIMs and PIM–PIs, PIM-derived thermally rearranged (TR), and carbon molecular sieve (CMS) membrane materials as well as PIM-based thin film composite membranes for a wide range of energy-intensive gas and liquid separations. In less than two decades, PIMs have significantly lifted the performance upper bounds in H2/N2, H2/CH4, O2/N2, CO2/N2, and CO2/CH4 separations. However, PIMs are still limited by their insufficient gas-pair selectivity to be considered as promising materials for challenging industrial separations such as olefin/paraffin separations. An optimum pore size distribution is required to further improve the selectivity of a PIM for a given application. Specific attention is given to the potential use of PIM-based CMS membranes for energy-intensive CO2/CH4, N2/CH4, C2H4/C2H6, and C3H6/C3H8 separations, and thin film composite membranes containing PIM motifs for liquid separations.
  • Research data supporting "High-mobility, trap-free charge transport in conjugated polymer diodes"

    Nikolka, Mark; Broch, Katharina; Armitage, John; Hanifi, David; Nowack, Peer J.; Venkateshvaran, Deepak; Sadhanala, Aditya; Saska, Jan; Mascal, Mark; Jung, Seok-Heon; Lee, Jin-Kyun; McCulloch, Iain; Salleo, Alberto; Sirringhaus, Henning (Apollo - University of Cambridge Repository, 2021-09-14) [Dataset]
    Origin project including all source data used for Figures 1 to 5.The Project is structured in sub-folders, with one folder dedicated to a specfic Figure of the paper. Folder 1 includes SCLC diode characteristics measured for DPP-BTz SCLC diodes with and without additives. Folder 2 includes low-temperature measurements of diodes, extracted activation energies as well as dn/DE values extracted by SCLC-spectroscopy. Folder 3 includes measured diode characteristics of IDT-BT, MEH:PPV and DPP-DTT SCLC diodes, corresponding dn/dE values and PDS spectroscopy data for these materials. The last Folder includes stability measuremtns of DPP-BTz diodes showing the evolution over 10k IV-characteristics. Any additional data from the paper (such as thoese shown in the SI or GIWAXs data) is available on request. Format
  • An Aqueous Mg 2+ -Based Dual-Ion Battery with High Power Density

    Zhu, Yunpei; Yin, Jun; Emwas, Abdul-Hamid; Mohammed, Omar F.; Alshareef, Husam N. (Advanced Functional Materials, Wiley, 2021-09-13) [Article]
    Rechargeable Mg batteries promise low-cost, safe, and high-energy alternatives to Li-ion batteries. However, the high polarization strength of Mg2+ leads to its strong interaction with electrode materials and electrolyte molecules, resulting in sluggish Mg2+ dissociation and diffusion as well as insufficient power density and cycling stability. Here an aqueous Mg2+-based dual-ion battery is reported to bypass the penalties of slow dissociation and solid-state diffusion. This battery chemistry utilizes fast redox reactions on the polymer electrodes, i.e., anion (de)doping on the polyaniline (PANI) cathode and (de)enolization upon incorporating Mg2+ on the polyimide anode. The kinetically favored and stable electrodes depend on designing a saturated aqueous electrolyte of 4.5 m Mg(NO3)2. The concentrated electrolyte suppresses the irreversible deprotonation reaction of the PANI cathode to enable excellent stability (a lifespan of over 10 000 cycles) and rate performance (33% capacity retention at 500 C) and avoids the anodic parasitic reaction of nitrate reduction to deliver the stable polyimide anode (86.2% capacity retention after 6000 cycles). The resultant full Mg2+-based dual-ion battery shows a high specific power of 10 826 W kg−1, competitive with electrochemical supercapacitors. The electrolyte and electrode chemistries elucidated in this study provide an alternative approach to developing better-performing Mg-based batteries.
  • Design of experiment optimization of aligned polymer thermoelectrics doped by ion-exchange

    Huang, Yuxuan; Lukito Tjhe, Dionisius Hardjo; Jacobs, Ian; Jiao, Xuechen; He, Qiao; Statz, Martin; Ren, Xinglong; Huang, Xinyi; McCulloch, Iain; Heeney, Martin; McNeill, Christopher R.; Sirringhaus, Henning (Applied Physics Letters, AIP Publishing, 2021-09-13) [Article]
    Organic thermoelectrics offer the potential to deliver flexible, low-cost devices that can directly convert heat to electricity. Previous studies have reported high conductivity and thermoelectric power factor in the conjugated polymer poly[2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene] (PBTTT). Here, we investigate the thermoelectric properties of PBTTT films in which the polymer chains were aligned uniaxially by mechanical rubbing, and the films were doped by a recently developed ion exchange technique that provides a choice over the counterions incorporated into the film, allowing for more optimized morphology and better stability than conventional charge transfer doping. To optimize the polymer alignment process, we took advantage of two Design of Experiment (DOE) techniques: regular two-level factorial design and central composite design. Rubbing temperature Trub and post-alignment annealing temperature Tanneal were the two factors that were most strongly correlated with conductivity. We were able to achieve high polymer alignment with a dichroic ratio >15 and high electrical conductivities of up to 4345 S/cm for transport parallel to the polymer chains, demonstrating that the ion exchange method can achieve conductivities comparable/higher than conventional charge transfer doping. While the conductivity of aligned films increased by a factor of 4 compared to unaligned films, the Seebeck coefficient (S) remained nearly unchanged. The combination of DOE methodology, high-temperature rubbing, and ion exchange doping provides a systematic, controllable strategy to tune structure–thermoelectric property relationships in semiconducting polymers
  • Local sensorimotor control and learning in robotics with organic neuromorphic electronics

    Krauhausen, Imke; Gkoupidenis, Paschalis; Melianas, Armantas; Keene, Scott T.; Lieberth, Katharina; Ledanseur, Hadrien; Sheelamanthula, Rajendar; Koutsouras, Dimitrios; Torricelli, Fabrizio; McCulloch, Iain; Blom, Paul W. M.; Salleo, Alberto; van de Burgt, Yoeri; Giovannitti , Alexander (Fundació Scito, 2021-09-13) [Conference Paper]
    Artificial intelligence applications have demonstrated their enormous potential for complex processing over the last decade, however they still lack the efficiency and computing capacity of the brain. In living organisms, data signals are represented by sensory and motor processes that are distributed, locally merged and capable of forming dynamic sensorimotor associations through volatile and non-volatile connections. Using similar computational primitives, neuromorphic circuits offer a new way of intelligent information processing that makes it possible to adaptively oberserve, anaylze, operate and interact in real-world scenarios [1-6]. In this work we present a small-scale, locally-trained organic neuromorphic circuit for sensorimotor control and learning, on a robot navigating inside a maze. By connecting the neuromorphic circuit directly to environmental stimuli through sensor signals, the robot is able to respond adaptively to sensory cues and consequently forms a behavioral association to follow the way to the exit. The on-chip sensorimotor integration with low-voltage organic neuromorphic electronics opens the way towards stand-alone, brain-inspired circuitry in autonomous and intelligent robotics.
  • Interfacial Model Deciphering High-Voltage Electrolytes for High Energy Density, High Safety, and Fast-Charging Lithium-Ion Batteries

    Zou, Yeguo; Cao, Zhen; Zhang, Junli; Wahyudi, Wandi; Wu, Yingqiang; Liu, Gang; Li, Qian; Cheng, Haoran; Zhang, Dongyu; Park, Geon-Tae; Cavallo, Luigi; Anthopoulos, Thomas D.; Wang, Limin; Sun, Yang-Kook; Ming, Jun (Advanced Materials, Wiley, 2021-09-12) [Article]
    High-voltage lithium-ion batteries (LIBs) enabled by high-voltage electrolytes can effectively boost energy density and power density, which are critical requirements to achieve long travel distances, fast-charging, and reliable safety performance for electric vehicles. However, operating these batteries beyond the typical conditions of LIBs (4.3 V vs Li/Li+) leads to severe electrolyte decomposition, while interfacial side reactions remain elusive. These critical issues have become a bottleneck for developing electrolytes for applications in extreme conditions. Herein, an additive-free electrolyte is presented that affords high stability at high voltage (4.5 V vs Li/Li+), lithium-dendrite-free features upon fast-charging operations (e.g., 162 mAh g−1 at 3 C), and superior long-term battery performance at low temperature. More importantly, a new solvation structure-related interfacial model is presented, incorporating molecular-scale interactions between the lithium-ion, anion, and solvents at the electrolyte–electrode interfaces to help interpret battery performance. This report is a pioneering study that explores the dynamic mutual-interaction interfacial behaviors on the lithium layered oxide cathode and graphite anode simultaneously in the battery. This interfacial model enables new insights into electrode performances that differ from the known solid electrolyte interphase approach to be revealed, and sets new guidelines for the design of versatile electrolytes for metal-ion batteries.
  • Thermo-Responsive Membranes from Blends of PVDF and PNIPAM-b-PVDF Block Copolymers with Linear and Star Architectures

    Algarni, Fatimah; Musteata, Valentina-Elena; Falca, Gheorghe; Chisca, Stefan; Hadjichristidis, Nikos; Nunes, Suzana Pereira (Macromolecules, American Chemical Society (ACS), 2021-09-10) [Article]
    We report the synthesis of poly(n-isopropylacrylamide)-b-poly(vinylidene fluoride), (PNIPAM-b-PVDF), copolymers with linear and star structures, as well as the self-assembly and fabrication of thermo-responsive membranes from blends of these block copolymers and a linear PVDF homopolymer. The synthesis was achieved by reversible addition–fragmentation chain-transfer sequential copolymerization using mono- or multifunctional transfer agents. The self-assembly in bulk and selective solvents was investigated. The PVDF blocks are crystallizable and hydrophobic and the PNIPAM thermo-responsive in water. The morphology is dominated by the breakout crystallization of the PVDF block. Nanoporous membranes were fabricated by non-solvent-induced phase-separation method. The membranes revealed a macroscale zig–zag morphology, which is dependent on the block copolymer architecture. Due to the presence of PNIPAM, these membranes exhibited thermo-responsive behavior with water permeability and rejection alternately varying with the operating temperature, which is reversible in multiple heating–cooling cycles.
  • Ambipolar inverters based on cofacial vertical organic electrochemical transistor pairs for biosignal amplification

    Rashid, Reem B.; du, weiyuan; Griggs, Sophie; Maria, Iuliana P.; McCulloch, Iain; Rivnay, Jonathan (Science Advances, American Association for the Advancement of Science (AAAS), 2021-09-08) [Article]
    On-site signal amplification for bioelectronic sensing is a desirable approach to improving recorded signal quality and to reducing the burden on signal transmission and back-end electronics. While organic electrochemical transistors (OECTs) have been used as local transducers of bioelectronic signals, their current output presents challenges for implementation. OECT-based circuits offer new opportunities for high-performance signal processing. In this work, we introduce an active sensing node based on cofacial vertical OECTs forming an ambipolar complementary inverter. The inverter, which shows a voltage gain of 28, is composed of two OECTs on opposite side walls of a single active area, resulting in a footprint identical to a planar OECT. The inverter is used as an analog voltage preamplifier for recording electrocardiogram signals when biased at the input voltage corresponding to peak gain. We further demonstrate compatibility with nontraditional fabrication methods with potential benefits for rapid prototyping and large-area printed electronics.
  • Illuminating the Intrinsic Effect of Water Co-feeding on Methane Dehydroaromatization: A Comprehensive Study

    Caglayan, Mustafa; Paioni, Alessandra Lucini; Dereli, Busra; Shterk, Genrikh; Hita, Idoia; Abou-Hamad, Edy; Pustovarenko, Alexey; Emwas, Abdul-Hamid M.; Dikhtiarenko, Alla; Castaño, Pedro; Cavallo, Luigi; Baldus, Marc; Chowdhury, Abhishek Dutta; Gascon, Jorge (ACS Catalysis, American Chemical Society (ACS), 2021-09-07) [Article]
    Among all catalytic natural gas valorization processes, methane dehydroaromatization (MDA) still has a great potential to be utilized at an industrial level. Although the use of Mo/H-ZSM-5 as an MDA catalyst was first reported almost three decades ago, the process is yet to be industrialized, because of its inherent challenges. In order to improve the overall catalytic performance and lifetime, the co-feeding of water constitutes a promising option, because of its abundance and nontoxicity. Although water’s (limited) positive influence on catalyst lifetime has earlier been exhibited, the exact course of action (like mechanism or the water effect on active sites) is yet to be established. To bridge this knowledge gap, in this work, we have performed an in-depth investigation to elucidate the effects of water co-feeding over a well-dispersed Mo/H-ZSM-5 catalyst by using an array of advanced characterization techniques (nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetry–temperature-programmed oxidation/mass spectroscopy (TG-TPO/MS), scanning transmission electron microscopy (STEM), N2 physisorption, Raman spectroscopy, inductively coupled plasma–optical emission spectroscopy (ICP-OES)). Our results demonstrate that the addition of water results in the occurrence of steam reforming (of both coke and methane) in parallel to MDA. Moreover, the presence of water affects the reducibility of Mo sites, as corroborated with computational analysis to examine the state and locality of Mo sites under various water levels and transformation of the catalyst structure during deactivation. We anticipate that our comprehensive study of the structure–function relationship on Mo/H-ZSM-5 under humid MDA conditions will be beneficial for the development of future methane valorization technologies.
  • Linked Nickel Oxide/Perovskite Interface Passivation for High-Performance Textured Monolithic Tandem Solar Cells

    Zhumagali, Shynggys; Isikgor, Furkan Halis; Maity, Partha; Yin, Jun; Ugur, Esma; de Bastiani, Michele; Subbiah, Anand Selvin; Mirabelli, Alessandro James; Azmi, Randi; Harrison, George T.; Troughton, Joel; Aydin, Erkan; Liu, Jiang; Allen, Thomas; Rehman, Atteq Ur; Baran, Derya; Mohammed, Omar F.; De Wolf, Stefaan (Advanced Energy Materials, Wiley, 2021-09-05) [Article]
    Sputtered nickel oxide (NiOx) is an attractive hole-transport layer for efficient, stable, and large-area p-i-n metal-halide perovskite solar cells (PSCs). However, surface traps and undesirable chemical reactions at the NiOx/perovskite interface are limiting the performance of NiOx-based PSCs. To address these issues simultaneously, an efficient NiOx/perovskite interface passivation strategy by using an organometallic dye molecule (N719) is reported. This molecule concurrently passivates NiOx and perovskite surface traps, and facilitates charge transport. Consequently, the power conversion efficiency (PCE) of single-junction p-i-n PSCs increases from 17.3% to 20.4% (the highest reported value for sputtered-NiOx based PSCs). Notably, the N719 molecule self-anchors and conformally covers NiOx films deposited on complex surfaces. This enables highly efficient textured monolithic p-i-n perovskite/silicon tandem solar cells, reaching PCEs up to 26.2% (23.5% without dye passivation) with a high processing yield. The N719 layer also forms a barrier that prevents undesirable chemical reactions at the NiOx/perovskite interface, significantly improving device stability. These findings provide critical insights for improved passivation of the NiOx/perovskite interface, and the fabrication of highly efficient, robust, and large-area perovskite-based optoelectronic devices.
  • The Complex Crystal Structure and Abundant Local Defects of Zeolite EMM-17 Unraveled by Combined Electron Crystallography and Microscopy

    Liu, Xiaona; Liu, Lingmei; Pan, Tingting; Yan, Nana; Dong, Xinglong; Li, Yuanhao; Chen, Lu; Tian, Peng; Han, Yu; Guo, Peng; Liu, Zhongmin (Angewandte Chemie International Edition, Wiley, 2021-09-02) [Article]
    Structure determination of zeolites is of great significance for understanding their fascinating properties. In this study, we successfully solve one of polymorphic structures (polymorph A) of zeolite EMM-17, which can only crystallize in sub-micron-sized crystals while containing complex stacking disorders, from the three-dimensional (3D) electron diffraction (ED) data. This is the first time that the atomic structure of this polymorph has been ab initio solved, and the result reveals a unique 10(12) X 10(12) X 11-ring channel system. Moreover, we acquire the first atomic-resolution images of EMM-17 using integrated differential phase-contrast scanning transmission electron microscopy. The images allow us to directly observe polymorphs B and C and discover a large number of local structural defects. Based on structural features unraveled from the reciprocal-space 3D ED data and real-space images, we propose a series of energetically feasible local structures in EMM-17. In addition, we demonstrate that the unique porous structure of EMM-17 enables efficient kinetic separation of C6 alkane isomers.
  • Methane decomposition to produce hydrogen and carbon nanomaterials over costless, iron-containing catalysts

    Qian, Jing Xia; Liu, Da Bin; Basset, Jean-Marie; Zhou, Lu (Journal of Cleaner Production, Elsevier BV, 2021-09-01) [Article]
    In this work, a series of iron-containing materials (not laboratory-synthesized but from natural, industrial raw materials, by-products or wastes), such as iron concentrate powder, fine/coarse ash and steel slag from steel plants and volcanic mud powder, were investigated as catalysts for methane decomposition. These catalysts exhibited relatively good methane conversion under the following conditions: 2.0 g of catalyst, 50 mL/min CH4, 900 °C for 5 h, even without hydrogen pre-reduction. Fe2O3 species on these samples were found to be gradually reduced by methane to Fe3O4, FeO and then finally into Fe0 active species. When methane decomposed onto the Fe0 active sites, Fe3C species would form to deposit graphite around themselves to finally form carbon nanomaterials, showing possible application in the oxygen evolution reaction and in Li-ion batteries as anode electrodes. Furthermore, using the best catalyst, iron concentrate powder, the effect of temperature and gas hourly space velocity was studied, where 900 °C and 3 L/gcat·h were determined as the optimized reaction conditions to reach the highest carbon/hydrogen yield.
  • Fluorinated thin-film composite membranes for nonpolar organic solvent nanofiltration

    Alduraiei, Fadhilah H.; Manchanda, Priyanka; Pulido Ponce de Leon, Bruno Antonio; Szekely, Gyorgy; Nunes, Suzana Pereira (Separation and Purification Technology, Elsevier BV, 2021-09) [Article]
    Polyamide (PA) is highly effective as a selective layer in case of nanofiltration (NF) membranes, mainly for filtering water and other polar solvents. The incorporation of fluorinated monomers in a polyamide network is a novel strategy for obtaining membranes with enhanced permeability in case of nonpolar solvents. In this study, PA thin-film composite membranes were prepared by interfacially reacting trimesoyl chloride (TMC) and 4,4ʹ-(hexafluoroisopropylidene)bis(benzoyl chloride) (HFBC) in an organic phase with 5-trifluoromethyl-1,3-phenylenediamine (TFMPD) in an aqueous phase in a single step. The resulting membrane obtained using HFBC exhibited a considerably increased nonpolar solvent flux and selectivity in the nanofiltration range. Thus, the hydrophobicity of the PA layer and its permeance are effectively enhanced because of the incorporation of the fluorinated monomer. Therefore, high-performance membranes can be obtained for nonpolar solvent separation in petroleum refineries and purification in the pharmaceutical industry.
  • Prediction of protein assemblies, the next frontier: The CASP14-CAPRI experiment.

    Lensink, Marc F.; Brysbaert, Guillaume; Mauri, Théo; Nadzirin, Nurul; Velankar, Sameer; Chaleil, Raphaël A G; Clarence, Tereza; Bates, Paul A; Kong, Ren; Liu, Bin; Yang, Guangbo; Liu, Ming; Shi, Hang; Lu, Xufeng; Chang, Shan; Roy, Raj S; Quadir, Farhan; Liu, Jian; Cheng, Jianlin; Antoniak, Anna; Czaplewski, Cezary; GiełdoŃ, Artur; Kogut, Mateusz; Lipska, Agnieszka G; Liwo, Adam; Lubecka, Emilia A; Maszota-Zieleniak, Martyna; Sieradzan, Adam K; Ślusarz, Rafał; Wesołowski, Patryk A; ZiĘba, Karolina; Del Carpio Muñoz, Carlos A; Ichiishi, Eiichiro; Harmalkar, Ameya; Gray, Jeffrey J; Bonvin, Alexandre M.J.J.; Ambrosetti, Francesco; Honorato, Rodrigo Vargas; Jandova, Zuzana; Jiménez-García, Brian; Koukos, Panagiotis I; Van Keulen, Siri; van Noort, Charlotte W; Réau, Manon; Roel-Touris, Jorge; Kotelnikov, Sergei; Padhorny, Dzmitry; Porter, Kathryn A; Alekseenko, Andrey; Ignatov, Mikhail; Desta, Israel; Ashizawa, Ryota; Sun, Zhuyezi; Ghani, Usman; Hashemi, Nasser; Vajda, Sandor; Kozakov, Dima; Rosell, Mireia; Rodríguez-Lumbreras, Luis A; Fernandez-Recio, Juan; Karczynska, Agnieszka; Grudinin, Sergei; Yan, Yumeng; Li, Hao; Lin, Peicong; Huang, Sheng-You; Christoffer, Charles; Terashi, Genki; Verburgt, Jacob; Sarkar, Daipayan; Aderinwale, Tunde; Wang, Xiao; Kihara, Daisuke; Nakamura, Tsukasa; Hanazono, Yuya; Gowthaman, Ragul; Guest, Johnathan D; Yin, Rui; Taherzadeh, Ghazaleh; Pierce, Brian G; Barradas Bautista, Didier; Cao, Zhen; Cavallo, Luigi; Oliva, Romina; Sun, Yuanfei; Zhu, Shaowen; Shen, Yang; Park, Taeyong; Woo, Hyeonuk; Yang, Jinsol; Kwon, Sohee; Won, Jonghun; Seok, Chaok; Kiyota, Yasuomi; Kobayashi, Shinpei; Harada, Yoshiki; Takeda-Shitaka, Mayuko; Kundrotas, Petras J; Singh, Amar; Vakser, Ilya A; DapkŪnas, Justas; Olechnovič, Kliment; Venclovas, Česlovas; Duan, Rui; Qiu, Liming; Zhang, Shuang; Zou, Xiaoqin; Wodak, Shoshana J (Proteins, Wiley, 2021-08-28) [Article]
    We present the results for CAPRI Round 50, the 4th joint CASP-CAPRI protein assembly prediction challenge. The Round comprised a total of 12 targets, including 6 dimers, 3 trimers, and 3 higher-order oligomers. Four of these were easy targets, for which good structural templates were available either for the full assembly, or for the main interfaces (of the higher-order oligomers). Eight were difficult targets for which only distantly related templates were found for the individual subunits. Twenty-five CAPRI groups including 8 automatic servers submitted ~1250 models per target. Twenty groups including 6 servers participated in the CAPRI scoring challenge submitted ~190 models per target. The accuracy of the predicted models was evaluated using the classical CAPRI criteria. The prediction performance was measured by a weighted scoring scheme that takes into account the number of models of acceptable quality or higher submitted by each group as part of their 5 top-ranking models. Compared to the previous CASP-CAPRI challenge, top performing groups submitted such models for a larger fraction (70-75%) of the targets in this Round, but fewer of these models were of high accuracy. Scorer groups achieved stronger performance with more groups submitting correct models for 70-80% of the targets or achieving high accuracy predictions. Servers performed less well in general, except for the MDOCKPP and LZERD servers, who performed on par with human groups. In addition to these results, major advances in methodology are discussed, providing an informative overview of where the prediction of protein assemblies currently stands.
  • Structural insights in mammalian sialyltransferases and fucosyltransferases: We have come a long way, but it is still a long way down

    Grewal, Ravneet Kaur; Shaikh, Abdul Rajjak; Gorle, Suresh; Kaur, Manjeet; Videira, Paula Alexendra; Cavallo, Luigi; Chawla, Mohit (Molecules, MDPI AG, 2021-08-27) [Article]
    Mammalian cell surfaces are modified with complex arrays of glycans that play major roles in health and disease. Abnormal glycosylation is a hallmark of cancer; terminal sialic acid and fucose in particular have high levels in tumor cells, with positive implications for malignancy. Increased sialylation and fucosylation are due to the upregulation of a set of sialyltransferases (STs) and fucosyltransferases (FUTs), which are potential drug targets in cancer. In the past, several advances in glycostructural biology have been made with the determination of crystal structures of several important STs and FUTs in mammals. Additionally, how the independent evolution of STs and FUTs occurred with a limited set of global folds and the diverse modular ability of catalytic domains toward substrates has been elucidated. This review highlights advances in the understanding of the structural architecture, substrate binding interactions, and catalysis of STs and FUTs in mammals. While this general understanding is emerging, use of this information to design inhibitors of STs and FUTs will be helpful in providing further insights into their role in the manifestation of cancer and developing targeted therapeutics in cancer.
  • Ionic Functionalization of Multivariate Covalent Organic Frameworks to Achieve Exceptionally High Iodine Capture Capacity.

    Xie, Yaqiang; Pan, Tingting; Lei, Qiong; Chen, Cailing; Dong, Xinglong; Yuan, Youyou; Shen, Jie; Cai, Yichen; Zhou, Chunhui; Pinnau, Ingo; Han, Yu (Angewandte Chemie (International ed. in English), Wiley, 2021-08-25) [Article]
    Adsorption-based iodine (I 2 ) capture is of great potential for the treatment of radioactive nuclear waste. Here we employ a "multivariate" synthetic strategy to construct ionic covalent organic frameworks (iCOFs) with large surface area, high pore volume, and abundant binding sites for I 2 capture. The optimized material iCOF-AB-50 exhibits static I 2 uptake capacity of 10.21 g·g -1 at 75 °C, and dynamic uptake capacity of 2.79 g·g -1 at ~400 ppm of I 2 and 25 °C, far exceeding the performances of previously reported adsorbents under similar conditions. It also shows fast adsorption kinetics, good moisture tolerance, and full reusability. The promoting effect of ionic groups on I 2 adsorption has been elucidated by experimentally identifying the iodine species adsorbed at different sites and calculating their binding energies. This work demonstrates the essential role of balancing the textural properties and binding sites of the adsorbent in achieving high I 2 capture performance.
  • Unactivated Alkyl Chloride Reactivity in Excited-State Palladium Catalysis

    Muralirajan, Krishnamoorthy; Kancherla, Rajesh; Gimnkhan, Aidana; Rueping, Magnus (Organic Letters, American Chemical Society (ACS), 2021-08-25) [Article]
    Excited-state palladium catalysis is an efficient process for the alkylation of diverse organic compounds via the generation of alkyl radicals from alkyl bromides and iodides. However, the generation of alkyl radicals from more stable alkyl chlorides remains challenging. Herein, we demonstrate the excited-state palladium-catalyzed synthesis of oxindoles and isoquinolinediones via alkylation/annulation reaction by overcoming inherent limitations associated with unactivated C(sp<sup>3</sup>)-Cl bond activation at room temperature.
  • Possible Misidentification of Heteroatom Species in Scanning Transmission Electron Microscopy Imaging of Zeolites

    Liu, Dong; Liu, Lingmei; Wu, Kepeng; Zhou, Jinfei; Cheng, Qingpeng; Lv, Jia; Cao, Tong; Zhang, Daliang; Lin, Fang; Han, Yu (The Journal of Physical Chemistry C, American Chemical Society (ACS), 2021-08-24) [Article]
    Atomic-resolution scanning transmission electron microscopy (STEM) can be used to determine the location and state of heteroatom species in zeolites, which is essential for understanding their catalytic behavior. However, because of the complexity of zeolite structures and low heteroatom content, STEM images must be carefully interpreted to avoid misidentification. In this work, Fe-doped silicalite-1 was used as an example to illustrate this problem by combining STEM image simulation and experiments. Simulation results indicated that, unless the specimen has only one unit cell thickness, it is impossible to reliably identify Fe atoms in a zeolite framework using high-angle annular dark-field STEM (HAADF-STEM). Experimental HAADF-STEM images could not distinguish Fe-doped silicalite-1 and Fe-free silicalite-1 samples, thus confirming the infeasibility of using HAADF-STEM to determine the preferential occupancy of Fe between different crystallographic sites. It was also found that integrated differential phase contrast STEM (iDPC-STEM) could detect extraframework Fe species located in microporous channels only when the physically adsorbed volatile organic compounds were properly removed before imaging. The findings of this investigation provide important precautions and guidance for related research work.

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