bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photochemical and Electrochemical Strategies towards Benzylic C−H Functionalization: A Recent Update
Authors: Oliva Monica , Coppola Guglielmo A. , Van der Eycken Erik V. , Sharma Upendra K. 
Published: February 2021

AbstractTransition metal‐catalysed processes have been widely used for the functionalization of inert C−H bonds. Strategies for the functionalization of the benzylic C−H position having a relatively weak C−H bond (bond dissociation energy∼ 80–90 kcal/mol) differ from the inert aliphatic and aromatic C−H positions with stronger C−H bonds. The recent advances in the direct activation of the benzylic position through the generation of C(sp3) radicals have demonstrated the potential of electrochemistry and photochemistry as a means for constructing new chemical bonds. This review will cover the recent progress of benzylic C−H functionalization through organic radical strategies employing photochemistry and electrochemistry as sustainable tools. In addition, the mechanistic details of the typical reactions have been included which, in turn, will help the researchers to look at this promising area from a different perspective towards new discoveries and often hidden opportunities.magnified image
Rapid Construction of Polycyclic Ketones and the Divergent Kinetic Resolution Using Ruthenium‐Catalyzed Transfer Hydrogenation
Authors: Lan Shouang , Zhang Hao , Chen Zhizhou , Yang Shuang , Fang Xinqiang 
Published: February 2021

AbstractA unique cascade sequence of vinylogous Michael addition‐Michael addition‐oxa‐Michael addition using dienone substrates was reported for the first time, achieving the rapid construction of 5/6/5 fused ring compounds in good yields with good to high stereoselectivities under mild conditions. Enantioenriched polycyclic rings can be obtained with high level of enantioselectivity by the stereodivergent resolution using ruthenium‐catalyzed transfer hydrogenation. The protocol provides a concise approach for the construction of the related fused ring substances.magnified image
Multicomponent Self‐Assembly of a Giant Heterometallic Polyoxotungstate Supercluster with Antitumor Activity
Authors: Liu Jian‐Cai , Wang Jie‐Fei , Han Qing , Shangguan Ping , Liu Lu‐Lu , Chen Li‐Juan , Zhao Jun‐Wei , Streb Carsten , Song Yu‐Fei 
Published: February 2021

AbstractThe hierarchical aggregation of molecular nanostructures from multiple components is a grand synthetic challenge, which requires highly selective linkage control. We demonstrate how two orthogonal linkage groups, that is, organotin and lanthanide cations, can be used to drive the aggregation of a giant molecular metal oxide superstructure. The title compound {[(Sn(CH3)2)2O]4{[CeW5O18] [TeW4O16][CeSn(CH3)2]4[TeW8O31]4}2}46− (1 a) features dimensions of ca. 2.2×2.3×3.4 nm3 and a molecular weight of ca. 25 kDa. Structural analysis shows the hierarchical aggregation from several independent subunits. Initial biomedical tests show that 1 features an inhibitory effect on the proliferation of HeLa cells based on an apoptosis pathway. In vivo experiments in mice reveal the antiproliferative activity of 1 and open new paths for further development of this new compound class.
Consecutive O−S/N−S Bond Cleavage in Gold‐Catalyzed Rearrangement Reactions of Alkynyl N‐Sulfinylimines
Authors: Tashiro Hiroki , Terada Masahiro , Nakamura Itaru 
Published: February 2021

AbstractGold‐catalyzed reactions of alkynyl N‐sulfinylimines were used to produce the corresponding 2H‐azirines possessing sulfenyl and acyl groups at the 3‐position of the azirine ring in good to excellent yields. These reactions involved internal transfer of the sulfinyl oxygen atom to form a thiooxime intermediate tethered to an α‐oxo gold carbene moiety. Subsequent insertion of the carbene into the N−S bond resulted in ring construction.
Quantitative Assessment of the Physical Virus Titer and Purity by Ultrasensitive Flow Virometry
Authors: Niu Qian , Ma Ling , Zhu Shaobin , Li Lan , Zheng Qisheng , Hou Jibo , Lian Hong , Wu Lina , Yan Xiaomei 
Published: February 2021

AbstractRapid quantification of viruses is vital for basic research on viral diseases as well as biomedical application of virus‐based products. Here, we report the development of a high‐throughput single‐particle method to enumerate intact viral particles by ultrasensitive flow virometry, which detects single viruses as small as 27 nm in diameter. The nucleic acid dye SYTO 82 was used to stain the viral (or vector) genome, and a laboratory‐built nano‐flow cytometer (nFCM) was employed to simultaneously detect the side‐scatter and fluorescence signals of individual viral particles. Using the bacteriophage T7 as a model system, intact virions were completely discriminated from empty capsids and naked viral genomes. Successful measurement of the physical virus titer and purity was demonstrated for recombinant adenoviruses, which could be used for gene delivery, therapeutic products derived from phage cocktails, and infected cell supernatants for veterinary vaccine production.
In Situ Synthesis of Uranyl‐Imprinted Nanocage for Selective Uranium Recovery from Seawater
Authors: Feng Lijuan , Wang Hui , Feng Tiantian , Yan Bingjie , Yu Qiuhan , Zhang Jiacheng , Guo Zhanhu , Yuan Yihui , Ma Chunxin , Liu Tao , Wang Ning 
Published: February 2021

AbstractAn adaptive coordination structure is vital for selective uranium extraction from seawater. By strategy of molecular imprinting, uranyl is introduced into a multivariate metal–organic framework (MOF) during the synthesis process to guide the in situ construction of proper nanocage structure for targeting uranyl binding. Except for the coordination between uranium with four oxygen from the materials, the axial oxygen of uranyl also forms hydrogen bonds with hydrogen from the phenolic hydroxyl group, which enhances the binding affinity of the material to uranyl. Attributing to the high binding affinity, the adsorbent shows high uranium binding selectivity to uranyl against not only the interfering metal ions, but also the carbonate group that coordinates with uranyl to form [UO2(CO)3]4− in seawater. In natural seawater, the adsorbent realizes a high uranium adsorption capacity of 7.35 mg g−1, together with an 18.38 times higher selectivity to vanadium.
Iron‐Catalyzed Tertiary Alkylation of Terminal Alkynes with 1,3‐Diesters via a Functionalized Alkyl Radical
Authors: Tian Ming‐Qing , Shen Zhen‐Yao , Zhao Xuefei , Walsh Patrick J. , Hu Xu‐Hong 
Published: February 2021

AbstractDirect oxidative C(sp)−H/C(sp3)−H cross‐coupling offers an ideal and environmentally benign protocol for C(sp)−C(sp3) bond formations. As such, reactivity and site‐selectivity with respect to C(sp3)−H bond cleavage have remained a persistent challenge. Herein is reported a simple method for iron‐catalyzed/silver‐mediated tertiary alkylation of terminal alkynes with readily available and versatile 1,3‐dicarbonyl compounds. The reaction is suitable for an array of substrates and proceeds in a highly selective manner even employing alkanes containing other tertiary, benzylic, and C(sp3)−H bonds alpha to heteroatoms. Elaboration of the products enables the synthesis of a series of versatile building blocks. Control experiments implicate the in situ generation of a tertiary carbon‐centered radical species.
A Crocheted Model Activity for Teaching Embryonic Lateral Folding to Medical Students
Authors: McConnell Sarah E.A. , Mooney Christopher J. 
Published: February 2021

Knowledge of embryology is foundational for understanding normal anatomy and birth defects, yet, embryology is a notoriously difficult subject for medical students. Embryonic lateral folding in particular is one of the most challenging concepts in embryology. Highly effective teaching methods that promote active engagement with dynamic, three‐dimensional models may be helpful for teaching this content. The aim of this study was to determine whether a hands‐on modeling activity utilizing premade crocheted pieces constructed from durable, inexpensive yarn helped medical students enrolled in a pre‐matriculation course to understand embryonic lateral folding. Change in knowledge was assessed using a pre–post design. Students also completed subjective evaluations regarding their satisfaction with the activity. Quiz scores in means (±SD) increased from 62.7 (±24.1) % before the activity to 77.0 (±17.1) % after the activity (P = 0.0495, two‐tailed pairedttest;d = 0.68). Generally, students reported that the activity was helpful and enjoyable, and the model pieces were easy to manipulate. These promising results suggest that hands‐on activities with dynamic, three‐dimensional models constitute an effective method for teaching embryology.
Regulating Spin Dynamics of Nitronyl Nitroxide Biradical Lanthanide Complexes through Introducing Different Transition Metals
Authors: Jing Pei , Xi Lu , Lu Jiao , Han Jing , Huang Xiaohui , Jin Chaoyi , Xie Junfang , Li Licun 
Published: February 2021

AbstractFour biradical‐Ln complexes with different transition metal ions, namely [LnM(hfac)5(NITPh‐PyPzbis)] (MII=MnII and LnIII=Gd 1, Dy 2; MII=NiII and LnIII=Tb 3, Dy 4), were prepared by the reaction of Ln(hfac)3 ⋅ 2H2O, Mn(hfac)2 ⋅ 2H2O or Ni(hfac)2 ⋅ 2H2O with NITPh‐PyPzbis biradical (hfac=hexafluoroacetylacetonate, NITPh‐PyPzbis=5‐(3‐(2‐pyridinyl)‐1H‐pyrazol‐1‐yl)‐1,3‐bis(1’‐oxyl‐3’‐oxido‐ 4’,4’,5’,5’‐tetramethyl‐4,5‐hydro‐1H‐imidazol‐2‐yl)benzene). In complexes 1–4, the NITPh‐PyPzbis biradical chelates one LnIII ion by means of its aminoxyl moieties and the transition metal ion is introduced through the two N donors from the pyridyl pyrazolyl moiety. Magnetic investigations indicate that complex 4 displays visible maxima in frequency/temperature‐dependent χ′′ signals with two‐step relaxation processes, but complex 2 exhibits no slow magnetization relaxation. The comparison of structure parameters of both Dy complexes indicates that the symmetries of coordination spheres of two Dy ions are D2d for 2 and C2v for 4, which thus probably results in different magnetic relaxation behaviors. This work provides new insight for improving properties of Ln‐biradical based SMMs.
Twisted intramolecular motion arrested in aggregated state emission and the nonlinear optical properties of pyrene pyrazoline derivatives
Authors: Karuppusamy A. , Kannan P. , Rajakumar K. , Zherebtsov D. 
Published: February 2021

AbstractHeterocyclic pyrene pyrazoline moieties containing similar structures but with differences in thiophene (PPT), furan (PPF) and pyridine (PPP) substitutions at the terminal molecules were synthesized. Their aggregation behaviour in THF–water mixtures was investigated and results demonstrated that PPT and PPP exhibited aggregation‐induced emission (AIE), whereas PPF exhibited aggregation‐induced blue‐shifted emission (AIBSE). PPT and PPP provided red‐shifted emission, while PPF had observed blue‐shifted emission at high water fractions of 70–90%, confirming that aggregation effects played a major role in the molecular structure. Two emission peaks from locally excited and twisted intramolecular charge transfer confirmed the twisted nature from the dihedral angle values of the free reorganized molecules that were completely restricted in high water fractions due to molecular aggregation. This was further confirmed from colour Commission Internationale de l’Eclairage values as well as dynamic light scattering analysis. Third‐order nonlinear optical properties were studied using a Nd:Yag laser beam Z‐scan technique at 532 nm. The open aperture Z‐scan revealed that PPT and PPF towards the peak point endured strong saturable absorption, whereas PPP indicated a strong reverse saturable absorption process. The AIE and AIBSE mechanisms from undergoing restricted twisting intramolecular motion in the aggregated luminogens provide great insight into new developments in AIEgen materials for these optoelectronic materials.
De novo sequence redesign of a functional Ras‐binding domain globally inverted the surface charge distribution and led to extreme thermostability
Authors: Liu Ruicun , Wang Jichao , Xiong Peng , Chen Quan , Liu Haiyan 
Published: February 2021

AbstractTo acquire extremely thermostable proteins of given functions is challenging for conventional protein engineering. Here we applied ABACUS, a statistical energy function we developed for de novo amino acid sequence design, to globally redesign a Ras‐binding domain (RBD), and obtained an extremely thermostable RBD that unfolds reversibly at above 110°C, the redesigned RBD experimentally confirmed to have expected structure and Ras‐binding interface. Directed evolution of the redesigned RBD improved its Ras‐binding affinity to the native protein level without excessive loss of thermostability. The designed amino acid substitutions were mostly at the protein surface. For many substitutions, strong epistasis or significantly differentiated effects on thermostability in the native sequence context relative to the redesigned sequence context were observed, suggesting the globally redesigned sequence to be unreachable through combining beneficial mutations of the native sequence. Further analyses revealed that by replacing 38 of a total of 48 non‐interfacial surface residues at once, ABACUS redesign was able to globally “invert” the protein's charge distribution pattern in an optimized way. Our study demonstrates that computational protein design provides powerful new tools to solve challenging protein engineering problems.
Optimization of Gold Nanoparticle Synthesis in Continuous‐Flow Micromixers Using Response Surface Methodology
Authors: Sarsfield Marissa , Roberts Alexa , Streletzky Kiril A. , Fodor Petru S. , Kothapalli Chandrasekhar R. 
Published: February 2021

AbstractGold nanoparticles (AuNPs) were synthesized in microfluidic mixers by means of response surface methodology (RSM). A reverse‐staggered herringbone micromixer was employed and reaction temperature, concentration ratio of reactants, Reynolds number, and pH of chloroauric acid were varied, with desired responses being particle size and peak intensity from UV spectroscopy. RSM was performed by simultaneously optimizing variable ranges to identify the best fit of polynomial equations to experimental data. Results revealed the individual and synergistic roles of each reaction variable on particle size and UV peak intensity, leading to identification of the largest design space. The effect of reaction variables on AuNP synthesis and particle size was confirmed in serpentine mixers.
Controlling Light‐Induced Proton Transfer from the GFP Chromophore
Authors: Langeland Jeppe , Persen Natascha W. , Gruber Elisabeth , Kiefer Hjalte V. , Kabylda Adil M. , Bochenkova Anastasia V. , Andersen Lars H. 
Published: February 2021

AbstractGreen Fluorescent Protein (GFP) is known to undergo excited‐state proton transfer (ESPT). Formation of a short H‐bond favors ultrafast ESPT in GFP‐like proteins, such as the GFP S65T/H148D mutant, but the detailed mechanism and its quantum nature remain to be resolved. Here we study in vacuo, light‐induced proton transfer from the GFP chromophore in hydrogen‐bonded complexes with two anionic proton acceptors, I− and deprotonated trichloroacetic acid (TCA−). We address the role of the strong H‐bond and the quantum mechanical proton‐density distribution in the excited state, which determines the proton‐transfer probability. Our study shows that chemical modifications to the molecular network drastically change the proton‐transfer probability and it can become strongly wavelength dependent. The proton‐transfer branching ratio is found to be 60 % for the TCA complex and 10 % for the iodide complex, being highly dependent on the photon energy in the latter case. Using high‐level ab initio calculations, we show that light‐induced proton transfer takes place in S1, revealing intrinsic photoacid properties of the isolated GFP chromophore in strongly bound H‐bonded complexes. ESPT is found to be very sensitive to the topography of the highly anharmonic potential in S1, depending on the quantum‐density distribution upon vibrational excitation. We also show that the S1 potential‐energy surface, and hence excited‐state proton transfer, can be controlled by altering the chromophore microenvironment.
The significance of left ventricular ejection time in heart failure with reduced ejection fraction
Authors: Alhakak Alia S. , Teerlink John R. , Lindenfeld Joann , Böhm Michael , Rosano Giuseppe M.C. , Biering‐Sørensen Tor 
Published: February 2021

AbstractLeft ventricular ejection time (LVET) is defined as the time interval from aortic valve opening to aortic valve closure, and is the phase of systole during which the left ventricle ejects blood into the aorta. LVET has been used for several decades to assess left ventricular function and contractility. However, there is a recent interest in LVET as a measure of therapeutic action for novel drugs in patients with heart failure with reduced ejection fraction (HFrEF), since LVET is shortened in these patients. This review provides an overview of the available information on LVET including methods of measuring LVET, mechanistic understanding of LVET, association of LVET with outcomes, mechanisms behind shortened LVET in HFrEF and the potential implications of drugs that affect and normalize LVET.
Step by step: Testing the staircase model of intergroup apologies
Authors: Nunney Samuel J. , Manstead Antony S. R. 
Published: February 2021

AbstractDespite the assumption that intergroup apologies should lead to forgiveness in the same way that interpersonal ones do, research suggests that this is not the case. We report two studies exploring the application of the Staircase Model of Intergroup Apologies (Wohl et al., 2011), in which an intergroup apology is embedded in a broader reconciliation process. Participants read accounts of an intergroup conflict (the “Troubles” in Northern Ireland) and subsequent efforts to achieve reconciliation, focusing on an official apology issued by the IRA. The content of this apology was varied such that the steps specified by the Staircase Model were presented either sequentially (Study 1) or in a manipulated order (Study 2). Both studies yielded results that were broadly supportive of the model. There were significant effects on measures of forgiveness, perceptions of the perpetrating group, and negative emotion (in particular disgust). The implications for enhancing the efficacy of intergroup apologies are discussed.
Monarch Butterfly (Danaus plexippus) Life-Stage Risks from Foliar and Seed-Treatment Insecticides
Authors: Krishnan Niranjana , Zhang Yang , Aust Melanie E. , Hellmich Richard L. , Coats Joel R. , Bradbury Steven P. 
Published: February 2021

Abstract
Conservation of North America's eastern monarch butterfly (Danaus plexippus) population would require establishment of milkweed (Asclepias spp.) and nectar plants in the agricultural landscapes of the north central United States. A variety of seed-treatment and foliar insecticides are used to manage early- and late-season pests in these landscapes. Thus, there is a need to assess risks of these insecticides to monarch butterfly life stages to inform habitat conservation practices. Chronic and acute dietary toxicity studies were undertaken with larvae and adults, and acute topical bioassays were conducted with eggs, pupae, and adults using 6 representative insecticides: beta-cyfluthrin (pyrethroid), chlorantraniliprole (anthranilic diamide), chlorpyrifos (organophosphate), imidacloprid, clothianidin, and thiamethoxam (neonicotinoids). Chronic dietary median lethal concentration values for monarch larvae ranged from 1.6 × 10–3 (chlorantraniliprole) to 5.3 (chlorpyrifos) μg/g milkweed leaf, with the neonicotinoids producing high rates of arrested pupal ecdysis. Chlorantraniliprole and beta-cyfluthrin were generally the most toxic insecticides to all life stages, and thiamethoxam and chlorpyrifos were generally the least toxic. The toxicity results were compared to insecticide exposure estimates derived from a spray drift model and/or milkweed residue data reported in the literature. Aerial applications of foliar insecticides are expected to cause high downwind mortality in larvae and eggs, with lower mortality predicted for adults and pupae. Neonicotinoid seed treatments are expected to cause little to no downslope mortality and/or sublethal effects in larvae and adults. Given the vagile behavior of nonmigratory monarchs, considering these results within a landscape-scale context suggests that adult recruitment will not be negatively impacted if new habitat is established in close proximity of maize and soybean fields in the agricultural landscapes of the north central United States. Environ Toxicol Chem 2021;40:1761–1777. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
Quantifying the impact of no‐till on runoff in southern Brazil at hillslope and catchment scales
Authors: Londero Ana L. , Minella Jean P. G. , Schneider Fabio J. A. , Deuschle Dinis , Menezes Danrlei , Evrard Olivier , Boeni Madalena , Merten Gustavo H. 
Published: February 2021

AbstractNo‐till (NT) is a conservation system that improves the hydrological regime of agricultural slopes by providing greater surface protection and benefits to the physical and hydrological properties of soils. However, the isolated use of NT is not enough to control runoff and its associated degradation processes. Therefore, this study aimed to evaluate the runoff of agricultural slopes under NT under different runoff control conditions by monitoring 63 rainfall events in two 2.4‐ha zero‐order catchments and 27 rainfall events in four 0.6‐ha macroplots. The catchments are paired and similar in terms of the type of soil and relief, but different regarding the presence of terraces. The macroplots have different soil and crop management systems. By using monitoring techniques, the hyetographs and hydrographs revealed the influence of the different types of management on the catchments and macroplots and allowed rainfall characteristics, runoff volume, runoff coefficients, water infiltration, peak runoff, response times, and curve number to be analysed. The terraces positively affected the NT and controlled runoff and related variables, in addition to infiltration significantly increasing and runoff reducing in the terraced catchment. All the hydrological information assessed pointed to the positive effects provided by the presence of the terraces. The results in the macroplots showed that high amounts of phytomass and/or chiselling do not control runoff and its correlated variables in medium and high magnitude events. The study concludes by underlining the need for additional measures to control runoff (terraces), even in areas under NT and with high phytomass production. Additionally, the study emphasizes the importance of monitoring at the catchment scale to better understand the hydrological behaviour of agricultural areas and provide the necessary parameters to effectively control runoff.