bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pentafluorphosphato‐Phenylalanine: Amphiphile Phosphotyrosinmimetika mit Fluor‐spezifischen Proteinwechselwirkungen
Authors: Accorsi Matteo , Tiemann Markus , Wehrhan Leon , Finn Lauren M. , Cruz Ruben , Rautenberg Max , Emmerling Franziska , Heberle Joachim , Keller Bettina G. , Rademann Jörg 
Published: March 2022

AbstractPhosphotyrosinreste sind essenzielle funktionale Schalter in Gesundheit und Krankheit. Daher sind Phosphotyrosin‐Biomimetika entscheidend für die Entwicklung von chemischen Werkzeugen und Wirkstoffmolekülen. Hier beschreiben wir die Entdeckung und Untersuchung von Pentafluorphosphato‐Aminosäuren als neuartige Phosphotyrosinmimetika. Ein mildes Pentafluorierungsprotokoll wurde entwickelt, zwei PF5‐Aminosäuren hergestellt und für die Peptidsynthese verwendet. Ihre Strukturen, Reaktivitäten und fluorspezifischen Wechselwirkungen wurden mittels NMR‐ und IR‐Spektroskopie, Röntgenstreuung und biologischen Assays untersucht. Das monoanionische PF5‐Motiv weist einen amphiphilen Charakter auf und bindet an hydrophobe Oberflächen, Wassermoleküle und Proteinbindungstaschen mittels Ladungs‐ und H−F‐Brückenwechselwirkungen. Die neuen Motive binden 25‐ bis 30‐fach stärker an die Phosphotyrosinbindungsstelle der Proteintyrosin‐Phosphatase PTP1B als das derzeit beste Biomimetikum, wie durch computergestützte Methoden wie Moleküldynamiksimulationen rationalisiert werden konnte.
Catalytic DNA Polymerization Can Be Expedited by Active Product Release**
Authors: Moerman Pepijn G. , Gavrilov Momcilo , Ha Taekjip , Schulman Rebecca 
Published: March 2022

AbstractThe sequence‐specific hybridization of DNA facilitates its use as a building block for designer nanoscale structures and reaction networks that perform computations. However, the strong binding energy of Watson–Crick base pairing that underlies this specificity also causes the DNA dehybridization rate to depend sensitively on sequence length and temperature. This strong dependency imposes stringent constraints on the design of multi‐step DNA reactions. Here we show how an ATP‐dependent helicase, Rep‐X, can drive specific dehybridization reactions at rates independent of sequence length, removing the constraints of equilibrium on DNA hybridization and dehybridization. To illustrate how this new capacity can speed up designed DNA reaction networks, we show that Rep‐X extends the range of conditions where the primer exchange reaction, which catalytically adds a domain provided by a hairpin template to a DNA substrate, proceeds rapidly.
Sustaining Electron Transfer Pathways Extends Biohybrid Photoelectrode Stability to Years
Authors: Friebe Vincent M. , Barszcz Agata J. , Jones Michael R. , Frese Raoul N. 
Published: March 2022

AbstractThe exploitation of natural photosynthetic enzymes in semi‐artificial devices constitutes an attractive and potentially sustainable route for the conversion of solar energy into electricity and solar fuels. However, the stability of photosynthetic proteins after incorporation in a biohybrid architecture typically limits the operational lifetime of biophotoelectrodes to a few hours. Here, we demonstrate ways to greatly enhance the stability of a mesoporous electrode coated with the RC‐LH1 photoprotein from Rhodobacter sphaeroides. By preserving electron transfer pathways, we extended operation under continuous high‐light to 33 days, and operation after storage to over two years. Coupled with large photocurrents that reached peak values of 4.6 mA cm−2, the optimized biophotoelectrode produced a cumulative output of 86 C cm−2, the largest reported performance to date. Our results demonstrate that the factor limiting stability is the architecture surrounding the photoprotein, and that biohybrid sensors and photovoltaic devices with operational lifetimes of years are feasible.
A Class of Readily Tunable Planar‐Chiral Cyclopentadienyl Rhodium(III) Catalysts for Asymmetric C–H Activation
Authors: Yan Xiaoqiang , Jiang Jijun , Wang Jun 
Published: March 2022

AbstractChiral half‐sandwich cyclopentadienyl rhodium(III) (CpRhIII) complexes are powerful catalysts for promoting asymmetric C−H activation reactions. Their preparation normally involved linking or embedding the Cp motif to or into a certain chiral backbone to forge the so‐called chiral Cp ligand. However, preparation of a planar‐chiral CpRhIII catalyst bearing a non‐chiral Cp ligand remains a formidable challenge and is rarely reported. We describe herein an unusual class of planar‐chiral rhodium catalysts bearing non‐chiral Cp ligands. Different from existing ones, this catalyst is readily tunable. Ten planar‐chiral only CpRhIII catalysts were prepared with ease, and successfully used in two enantioselective C−H activation reactions. Given its convenient synthesis and high structural tunability, these catalysts are expected to find more utilities in asymmetric C−H activation.
Dinitrogen Coordination to a High‐Spin Diiron(I/II) Species
Authors: Torres Juan F. , Oi Collin H. , Moseley Ian P. , El‐Sakkout Nabila , Knight Brian J. , Shearer Jason , García‐Serres Ricardo , Zadrozny Joseph M. , Murray Leslie J. 
Published: March 2022

AbstractDinitrogen coordination to iron centers underpins industrial and biological fixation in the Haber–Bosch process and by the FeM cofactors in the nitrogenase enzymes. The latter employ local high‐spin metal centers; however, iron–dinitrogen coordination chemistry remains dominated by low‐valent states, contrasting the enzyme systems. Here, we report a high‐spin mixed‐valent cis‐(μ‐1,2‐dinitrogen)diiron(I/II) complex [(FeBr)2(μ‐N2)Lbis]− (2), where [Lbis]− is a bis(β‐diketiminate) cyclophane. Field‐applied Mössbauer spectra, dc and ac magnetic susceptibility measurements, and computational methods support a delocalized S=7/2 Fe2N2 unit with D=−5.23 cm−1 and consequent slow magnetic relaxation.
Slow Synthesis Methodology‐Directed Immiscible Octahedral PdxRh1−x Dual‐Atom‐Site Catalysts for Superior Three‐Way Catalytic Activities over Rh
Authors: Tan Zhe , Haneda Masaaki , Kitagawa Hiroshi , Huang Bo 
Published: March 2022

AbstractThis study provided an effective strategy to construct dual‐atom sites by solid–solution alloying. A slow synthesis methodology was established for the solid–solution preparations as dual‐atom‐site catalysts. The atomic‐level homogeneous PdxRh1−x dual‐atom‐site catalysts were successfully synthesized over the whole composition range, as evidenced by X‐ray powder diffraction and scanning transmission electron microscope energy‐dispersive X‐ray spectroscopy mapping measurements. The challenging morphology formation in the immiscible alloys was achieved by an energy‐controlling process as the octahedral Rh‐rich alloys. The Pd0.3Rh0.7 dual‐atom‐site catalyst had unique surface states to activate the key reactants of CO and NO in the complex three‐way catalytic reactions, and it performed significantly better than pure Rh.
Boosting the Productivity of Electrochemical CO2Reduction to Multi‐Carbon Products by Enhancing CO2Diffusion through a Porous Organic Cage
Authors: Chen Chunjun , Yan Xupeng , Wu Yahui , Liu Shoujie , Zhang Xiudong , Sun Xiaofu , Zhu Qinggong , Wu Haihong , Han Buxing 
Published: March 2022

AbstractElectroreduction of CO2into valuable fuels and feedstocks offers a promising way for CO2utilization. However, the commercialization is limited by the low productivity. Here, we report a strategy to enhance the productivity of CO2electroreduction by improving diffusion of CO2to the surface of catalysts using porous organic cages (POCs) as an additive. It was noted that the Faradaic efficiency (FE) of C2+ products could reach 76.1 % with a current density of 1.7 A cm−2when Cu‐nanorod(nr)/CC3 (one of the POCs) was used, which were much higher than that using Cu‐nr. Detailed studies demonstrated that the hydrophobic pores of CC3 can adsorb a large amount of CO2for the reaction, and the diffusion of CO2in the CC3 to the nanocatalyst surface is easier than that in the liquid electrolyte. Thus, more CO2molecules make contact with the nanocatalysts in the presence of CC3, enhancing CO2reduction and inhibiting generation of H2.
Constructing Cu−C Bonds in a Graphdiyne‐Regulated Cu Single‐Atom Electrocatalyst for CO2 Reduction to CH4
Authors: Shi Guodong , Xie Yunlong , Du Lili , Fu Xinliang , Chen Xiaojie , Xie Wangjing , Lu Tong‐Bu , Yuan Mingjian , Wang Mei 
Published: March 2022

AbstractRegulating intermediates through elaborate catalyst design to control the reaction direction is crucial for promoting the selectivity of electrocatalytic CO2‐to‐CH4. M−C (M=metal) bonds are particularly important for tuning the multi‐electron reaction; however, its construction in nanomaterials is challenging. Here, via rational design of in situ anchoring of Cu SAs (single atoms) on the unique platform graphdiyne, we firstly realize the construction of a chemical bond Cu−C (GDY). In situ Raman spectroelectrochemistry and DFT calculations confirm that due to the fabrication of the Cu−C bond, during CO2 reduction, the formation of *OCHO intermediates is dominant rather than *COOH on Cu atoms, facilitating the formation of CH4. Therefore, we find that constructing the Cu−C bond in Cu SAs/GDY can supply an efficient charge transfer channel, but most importantly control the reaction intermediates and guide a more facile reaction pathway to CH4, thereby significantly boosting its catalytic performance. This work provides new insights on enhancing the selectivity for CO2RR at the atomic level.
Pentafluorophosphato‐Phenylalanines: Amphiphilic Phosphotyrosine Mimetics Displaying Fluorine‐Specific Protein Interactions
Authors: Accorsi Matteo , Tiemann Markus , Wehrhan Leon , Finn Lauren M. , Cruz Ruben , Rautenberg Max , Emmerling Franziska , Heberle Joachim , Keller Bettina G. , Rademann Jörg 
Published: March 2022

AbstractPhosphotyrosine residues are essential functional switches in health and disease. Thus, phosphotyrosine biomimetics are crucial for the development of chemical tools and drug molecules. We report here the discovery and investigation of pentafluorophosphato amino acids as novel phosphotyrosine biomimetics. A mild acidic pentafluorination protocol was developed and two PF5‐amino acids were prepared and employed in peptide synthesis. Their structures, reactivities, and fluorine‐specific interactions were studied by NMR and IR spectroscopy, X‐ray diffraction, and in bioactivity assays. The mono‐anionic PF5 motif displayed an amphiphilic character binding to hydrophobic surfaces, to water molecules, and to protein‐binding sites, exploiting charge and H−F‐bonding interactions. The novel motifs bind 25‐ to 30‐fold stronger to the phosphotyrosine binding site of the protein tyrosine phosphatase PTP1B than the best current biomimetics, as rationalized by computational methods, including molecular dynamics simulations.
Making sense of the black‐boxes: Toward interpretable text classification using deep learning models
Authors: Tao Jie , Zhou Lina , Hickey Kevin 
Published: March 2022

AbstractText classification is a common task in data science. Despite the superior performances of deep learning based models in various text classification tasks, their black‐box nature poses significant challenges for wide adoption. The knowledge‐to‐action framework emphasizes several principles concerning the application and use of knowledge, such as ease‐of‐use, customization, and feedback. With the guidance of the above principles and the properties of interpretable machine learning, we identify the design requirements for and propose an interpretable deep learning (IDeL) based framework for text classification models. IDeL comprises three main components: feature penetration, instance aggregation, and feature perturbation. We evaluate our implementation of the framework with two distinct case studies: fake news detection and social question categorization. The experiment results provide evidence for the efficacy of IDeL components in enhancing the interpretability of text classification models. Moreover, the findings are generalizable across binary and multi‐label, multi‐class classification problems. The proposed IDeL framework introduce a unique iField perspective for building trusted models in data science by improving the transparency and access to advanced black‐box models.
Evaluation of electroencephalography biomarkers for Angelman syndrome during overnight sleep
Authors: Levin Yuval , Hosamane Nishitha S. , McNair Taylor E. , Kunnam Shrujana S. , Philpot Benjamin D. , Fan Zheng , Sidorov Michael S. 
Published: March 2022

AbstractAngelman syndrome (AS) is a neurodevelopmental disorder caused by loss‐of‐function mutations in the maternal copy of the UBE3A gene. AS is characterized by intellectual disability, impaired speech and motor skills, epilepsy, and sleep disruptions. Multiple treatment strategies to re‐express functional neuronal UBE3A from the dormant paternal allele were successful in rodent models of AS and have now moved to early phase clinical trials in children. Developing reliable and objective AS biomarkers is essential to guide the design and execution of current and future clinical trials. Our prior work quantified short daytime electroencephalograms (EEGs) to define promising biomarkers for AS. Here, we asked whether overnight sleep is better suited to detect AS EEG biomarkers. We retrospectively analyzed EEGs from 12 overnight sleep studies from individuals with AS with age and sex‐matched Down syndrome and neurotypical controls, focusing on low frequency (2–4 Hz) delta rhythms and sleep spindles. Delta EEG rhythms were increased in individuals with AS during all stages of overnight sleep, but overnight sleep did not provide additional benefit over wake in the ability to detect increased delta. Abnormal sleep spindles were not reliably detected in EEGs from individuals with AS during overnight sleep, suggesting that delta rhythms represent a more reliable biomarker. Overall, we conclude that periods of wakefulness are sufficient, and perhaps ideal, to quantify delta EEG rhythms for use as AS biomarkers.Lay SummaryElectroencephalography (EEG) is a safe and reliable way of measuring abnormal brain activity in Angelman syndrome. We found that low‐frequency “delta” EEG rhythms are increased in individuals with Angelman syndrome during all stages of overnight sleep. Delta rhythms can be used as a tool to measure improvement in future clinical trials.
Structural Dynamics Support Electrostatic Interactions in the Active Site of Adenylate Kinase
Authors: Lawal Monsurat Motunrayo , Vaissier Welborn Valerie 
Published: March 2022

AbstractElectrostatic preorganization as well as structural and dynamic heterogeneity are often used to rationalize the remarkable catalytic efficiency of enzymes. However, they are often presented as incompatible because the generation of permanent electrostatic effects implies that the protein structure remains rigid. Here, we use a metric, electric fields, that can treat electrostatic contributions and dynamics effects on equal footing, for a unique perspective on enzymatic catalysis. We find that the residues that contribute the most to electrostatic interactions with the substrate in the active site of Adenylate Kinase (our working example) are also the most flexible residues. Further, entropy‐tuning mutations raise flexibility at the picosecond timescale where more conformations can be visited on short time periods, thereby softening the sharp heterogeneity normally visible at the microsecond timescale.
Investigation of a large‐scale adaptive concrete beam with integrated fluidic actuators
Authors: Burghardt Timon , Kelleter Christian , Bosch Matthias , Nitzlader Markus , Bachmann Matthias , Binz Hansgeorg , Blandini Lucio , Sobek Werner 
Published: March 2022

AbstractAs the world population keeps growing, so does the demand for new construction. Considering material resources are limited, it will be unfeasible to meet such demand employing conventional construction methods. A new resource‐saving approach is provided by adaptive structures. Using sensors, actuators and control units, structures are enabled to adapt to loads, for example, to compensate for deformations. Since deformations are dominant in the design of bending‐stressed load‐bearing structures, adaptivity enables such structures to be realized using less material and achieving the same load‐bearing capacity in comparison to conventional designs. This article presents a concrete beam of typical building dimensions that compensates deflections by means of integrated fluidic actuators. These actuators offer the possibility of reacting optimally to general loading. The investigation is carried out on an approximately 4‐m‐long beam with integrated hydraulic actuators. To ensure the overall functionality, accurate dimensioning of the beam as well as the hydraulic system is mandatory. Analytical design of the beam and actuation system are carried out for predimensioning. Experimental testing validates the function and demonstrates that the adaptive beam works as predicted. A fully compensation in deflection is possible. Therefore, a significant increase in load‐bearing capacity is possible with the same material input compared to conventional beams.
Macrocyclic Donor‐Acceptor Dyads Composed of Oligothiophene Half‐Cycles and Perylene Bisimides
Authors: Bold Kevin , Stolte Matthias , Shoyama Kazutaka , Krause Ana‐Maria , Schmiedel Alexander , Holzapfel Marco , Lambert Christoph , Würthner Frank 
Published: March 2022

AbstractA series of donor‐acceptor (D−A) macrocyclic dyads consisting of an electron‐poor perylene bisimide (PBI) π‐scaffold bridged with electron‐rich α‐oligothiophenes bearing four, five, six and seven thiophene units between the two phenyl‐imide substituents has been synthesized and characterized by steady‐state UV/Vis absorption and fluorescence spectroscopy, cyclic and differential pulse voltammetry as well as transient absorption spectroscopy. Tying the oligothiophene strands in a conformationally fixed macrocyclic arrangement leads to a more rigid π‐scaffold with vibronic fine structure in the respective absorption spectra. Electrochemical analysis disclosed charged state properties in solution which are strongly dependent on the degree of rigidification within the individual macrocycle. Investigation of the excited state dynamics revealed an oligothiophene bridge size‐dependent fast charge transfer process for the macrocyclic dyads upon PBI subunit excitation.
Chalcogen Bonding with Diaryl Ditellurides: Evidence from Solid State and Solution Studies.
Authors: Weiss Robin , Aubert Emmanuel , Groslambert Loic , Pale Patrick , Mamane Victor 
Published: March 2022

AbstractThe chalcogen bonding (ChB) ability of Te is studied in symmetrical diaryl ditellurides ArTeTeAr. Among the two Te σ‐holes, the one along the less polarized Te−Te bond was calculated as the more electropositive. This counter‐intuitive situation is due to the hyperconjugation contribution from Te lone pair to the σ* of the adjacent Te which coincides with σ‐hole along the more polarized Te−Ar bond. ArTeTeAr showed notable structural features in the solid state as a result of intermolecular Te⋅⋅⋅Te ChB, such as a Te4 rectangle through dimer aggregation or a triangular Te3 motif, where one Te interacts with both Te atoms of a neighboring molecule through both its σ‐hole and lone pair, in a slightly frustrated geometry. Lewis acidity of ArTeTeAr was also evaluated by NMR with R3PO as σ‐hole acceptors in different solvents. Thus, 125Te NMR allowed monitoring Te⋅⋅⋅O interaction and delivering association constants (Ka) for 1 : 1 adducts. The highest value of Ka=90 M−1 was measured for the adduct between ArTeTeAr bearing CF3 groups and Et3PO in cyclohexane. Notably, by using nBu3PO, Te⋅⋅⋅O interaction was revealed by 19F‐1H HOESY showing spatial proximity between CF3 and CH3 of nBu3PO.
Azetidines‐Containing Fluorescent Purine Analogs: Synthesis and Photophysical Properties
Authors: Hadidi Kaivin , Tor Yitzhak 
Published: March 2022

AbstractAnalogues of N,N‐dimethyladenine exploiting both thieno‐and isothiazolo‐pyrimidine cores were modified with 3‐subsituted azetidines to yield visibly emissive and responsive fluorophores. The emission quantum yields, among the highest seen for purine analogues (0.64 and 0.77 in water and dioxane respectively), correlated with the Hammett inductive constants of the substituents on the azetidine ring. Ribosylation of the difluoroazetidino‐modified nucleobase yielded an emissive nucleoside that displayed a substantially lower emission quantum yield in water, compared to the precursor nucleobase. Importantly, high emission quantum yield was restored in deuterium oxide, which highlights the potential impact of the sugar moiety on the photophysical features of fluorescent nucleosides, a functionality usually considered non‐chromophoric and photophysically benign.
Magnetic Resonance Imaging of Tumor‐Infiltrating Lymphocytes by Anti‐CD3‐Conjugated Iron Oxide Nanoparticles
Authors: Pournoori Negin , Oghabian Mohammad Ali , Irajirad Rasoul , Muhammadnejad Samad , Delavari H. Hamid 
Published: March 2022

AbstractImmune checkpoint blockade, considered a revolutionary approach in cancer treatment, is only effective in patients with high tumor‐infiltrating lymphocytes (TILs). This work aimed to investigate the feasibility of targeted contrast agent (CA) based on dextran‐coated superparamagnetic iron oxide nanoparticles (SPIONs‐DEX) for TILs detection by magnetic resonance imaging (MRI) studies. To do so, we synthesized an MRI CA by conjugating SPIONs‐DEX to an anti‐CD3 monoclonal antibody via cyanogen bromide as a cross‐linker. In vitro assessments demonstrated the higher labeling efficiency of the developed CA to CD3+ lymphocytes compared to SPIONs‐DEX. In vivo MRI of a xenograft model of CD3+ lymphocytes revealed the significant signal loss after the intravenous injection of the bioconjugate by ∼34 % and 21 % in T2*‐weighted and T2‐weighted images, respectively. The histopathological evaluation of xenograft tumors confirmed the labeling of lymphocytes by the targeted CA. This approach could open up a new horizon in the non‐invasive assessment of TILs to identify patients eligible for immunotherapy.
Lysine‐Functionalized SnO2for Efficient CO2Electroreduction into Formate
Authors: Lin Chen , Xu Zifan , Kong Xiangdong , Zheng Han , Geng Zhigang , Zeng Jie 
Published: March 2022

AbstractElectroreduction of CO2to HCOO−can be considered as the most economically valuable process. Herein, we developed lysine‐functionalized SnO2nanoparticles (SnO2‐lys) as an efficient catalyst for the electroreduction of CO2into HCOO−. During CO2electroreduction, SnO2‐lys achieved a Faradaic efficiency for HCOO−of higher than 80% over a wide range of applied potentials from −0.5 V to −2.3 V versus reversible hydrogen electrode (vs. RHE). Notably, the partial current density for HCOO−reached as high as −351.9 mA cm−2at −2.3 Vvs. RHE. On account of kinetic analysis and mechanistic study, lysine‐functionalized SnO2facilitated faradaic process and accelerated reaction kinetics via enhancing the CO2activation, thus promoting the catalytic performance of the electroreduction of CO2into HCOO−.