bluuebunny/crossref_metadata_2025_split huggingface dataset:
Low‐Spin and High‐Spin Perferryl Intermediates in Non‐Heme Iron Catalyzed Oxidations of Aliphatic C−H Groups
Authors: Zima Alexandra M. , Lyakin Oleg Y. , Bryliakov Konstantin P. , Talsi Evgenii P. 
Published: March 2021

AbstractThe selectivity patterns of iron catalysts of the Fe(PDP) family in aliphatic C−H oxidation with H2O2 have been studied (PDP=N,N′‐bis(pyridine‐2‐ylmethyl)‐2,2′‐bipyrrolidine). Cyclohexane, adamantane, 1‐bromo‐3,7‐dimethyloctane, 3,7‐dimethyloctyl acetate, (−)‐acetoxy‐p‐menthane, and cis‐1,2‐dimethylcyclohexane were used as substrates. The studied catalyst systems generate low‐spin (S=1/2) oxoiron(V) intermediates or high‐spin (S=3/2) oxoiron(V) intermediates, depending on the electron‐donating ability of remote substituents at the pyridine rings. The low‐spin perferryl intermediates demonstrate lower stability and higher reactivity toward aliphatic C−H groups of cyclohexane than their high‐spin congeners, according to the measured self‐decay and second‐order rate constants k1 and k2. Unexpectedly, there appears to be no uniform correlation between the spin state of the oxoiron(V) intermediates, and the chemo‐ and regioselectivity of the corresponding catalyst systems in the oxidation of the considered substrates. This contrasts with the asymmetric epoxidations by the same catalyst systems, in which case the epoxidation enantioselectivity increases when passing from the systems featuring the more reactive low‐spin perferryl intermediates to those with their less reactive high‐spin congeners.
[10]CPP‐Based Inclusion Complexes of Charged Fulleropyrrolidines. Effect of the Charge Location on the Photoinduced Electron Transfer
Authors: Stasyuk Olga A. , Stasyuk Anton J. , Solà Miquel , Voityuk Alexander A. 
Published: March 2021

AbstractA number of non‐covalently bound donor‐acceptor dyads, consisting of C60 as the electron acceptor and cycloparaphenylene (CPP) as the electron donor, have been reported. A hypsochromic shift of the charge transfer (CT) band in polar medium has been found in [10]CPP⊃Li+@C60. To explore this anomalous effect, we study inclusion complexes [10]CPP⊃Li+@C60‐MP, [10]CPP⊃C60‐MPH+, and [10]CPP⊃C60‐PPyMe+ formed by fulleropyrrolidine derivatives and [10]CPP using the DFT/TDDFT approach. We show that the introduction of a positively charged fragment into fullerene stabilizes CT states that become the lowest‐lying excited states. These charge‐separated states can be generated by the decay of locally excited states on a nanosecond to picosecond time scale. The distance of the charged fragment to the center of the fullerenic cage and its accessibility to the solvent determine the strength of the hypsochromic shift.
Cyclopentadienone Derivative Dimers as Tunable Photoswitches
Authors: Lu Ru‐Qiang , Zhuo You‐Zhen , Bao Yue‐Hua , Yang Lin‐Lin , Qu Hang , Tang Xiao , Wang Xin‐Chang , Li Zhi‐Hao , Cao Xiao‐Yu 
Published: March 2021

AbstractA series of photoswitchable cyclopentadienone derivative dimers bearing bromo, thienyl, 4‐(dimethylamino)phenyl, 3‐pyridinyl, 4‐nitrophenyl and cyano groups was designed and facilely synthesized. Photoswitching properties such as the photoconversions in the photostationary state (PSS), the thermal kinetics and thermal half‐lives of photoisomers were systematically investigated. These photoswitches show high fatigue resistance and large photoconversions in the PSS. This work proves that the photoswitching properties of photoswitches based on cyclopentadienone dimers can be tuned by substitution groups and also pave the way to functionalize the cyclopentadienone derivative dimer‐based photoswitch, which is important for its future applications.
Photo‐/Electroinduced Irreversible Isomerization of 2,2’‐Azobispyridine Ligands in Arene Ruthenium(II) Complexes
Authors: Long Jonathan , Kumar Divyaratan , Deo Claire , Retailleau Pascal , Dubacheva Galina V. , Royal Guy , Xie Juan , Bogliotti Nicolas 
Published: March 2021

AbstractNovel arene RuII complexes containing 2,2’‐azobispyridine ligands were synthesized and characterized by using 1H and 13C NMR spectroscopy, UV/vis spectroscopy, electrochemistry, DFT calculations and single‐crystal X‐ray diffraction. Z‐configured complexes featuring unprecedented seven‐membered chelate rings involving the nitrogen atom of both pyridines were isolated and were shown to undergo irreversible isomerization to the corresponding E‐configured five‐membered chelate complexes in response to light or electrochemical stimulus.
DNA‐Scaffolded Disulfide Redox Network for Programming Drug‐Delivery Kinetics
Authors: Ji Wei , Li Xiaodan , Xiao Mingshu , Sun Yueyang , Lai Wei , Zhang Hongbo , Pei Hao , Li Li 
Published: March 2021

AbstractIn response to specific stimuli, dynamic covalent materials enable the generation of new structures by reversibly forming/breaking chemical bonds, thus showing great potential for application in controlled drug release. However, using dynamic covalent chemistry to program drug‐delivery kinetics remains challenging. Herein, an in situ polymerization‐generated DNA‐scaffolded disulfide redox network (DdiSRN) is reported in which nucleic acids are used as a scaffold for dynamic disulfide bonds. The constructed DdiSRN allows selective release of loading cargos inside cancer cells in response to redox stimuli. Moreover, the density of disulfide bonds in network can be tuned by precise control over their position and number on DNA scaffolds. As a result, drug‐delivery kinetics can be programmed with a half‐life, t1/2, decreasing from 8.3 to 4.4 h, thus facilitating keeping an adequate drug concentration within the therapeutic window. Both in vitro and in vivo studies confirm that co‐delivery of DOX and siRNA in combination with fast drug release inside cells using this DdiSRN enhances the therapeutic effect on multidrug‐resistant cancer. This nontrivial therapeutic platform enabling kinetic control provides a good paradigm for precision cancer medicine.
Activated Self‐Resolution and Error‐Correction in Catalytic Reaction Networks**
Authors: Schaufelberger Fredrik , Ramström Olof 
Published: March 2021

AbstractUnderstanding the emergence of function in complex reaction networks is a primary goal of systems chemistry and origin‐of‐life studies. Especially challenging is to create systems that simultaneously exhibit several emergent functions that can be independently tuned. In this work, a multifunctional complex reaction network of nucleophilic small molecule catalysts for the Morita‐Baylis‐Hillman (MBH) reaction is demonstrated. The dynamic system exhibited triggered self‐resolution, preferentially amplifying a specific catalyst/product set out of a many potential alternatives. By utilizing selective reversibility of the products of the reaction set, systemic thermodynamically driven error‐correction could also be introduced. To achieve this, a dynamic covalent MBH reaction based on adducts with internal H‐transfer capabilities was developed. By careful tuning of the substituents, rate accelerations of retro‐MBH reactions of up to four orders of magnitude could be obtained. This study thus demonstrates how efficient self‐sorting of catalytic systems can be achieved through an interplay of several complex emergent functionalities.
On the Reactivity Enhancement of Graphene by Metallic Substrates towards Aryl Nitrene Cycloadditions
Authors: Yang Xiaojian , Chen Feiran , Kim Min A. , Liu Haitao , Wolf Lawrence M. , Yan Mingdi 
Published: March 2021

AbstractPristine graphene is fairly inert chemically, and as such, most application‐driven studies use graphene oxide, or reduced graphene oxide. Using substrates to modulate the reactivity of graphene represents a unique strategy in the covalent functionalization of this otherwise fairly inert material. It was found that the reactivity of pristine graphene towards perfluorophenyl azide (PFPA) can be enhanced by a metal substrate on which graphene is supported. Results on the extent of functionalization, defect density, and reaction kinetics all show that graphene supported on Ni (G/Ni) has the highest reactivity toward PFPA, followed by G/Cu and then G/silicon wafer. DFT calculations suggest that the metal substrate stabilizes the physisorbed nitrene through enhanced electron transfer to the singlet nitrene from the graphene surface assisted by the electron rich metal substrate. The G/Ni substantially stabilizes the singlet nitrene relative to G/Cu and the free‐standing graphene. The product structure is also predicted to be substrate dependent. These findings open up opportunities to enhance the reactivity of pristine graphene simply through the selection of the substrate. This also represents a new and powerful approach to increasing the reactivity of singlet nitrenes through direct electronic communication with graphene.
Binding of a TlCl Entity by a Tetragold Tetramercaptothiacalixarene Metalloligand via Metallophilic Interactions
Authors: Frank N. , Pryjomska‐Ray I. , Grubert L. , Hecht S. , Usvyat D. , Limberg C. 
Published: March 2021

AbstractThe successive auration of p‐tert‐butyltetramercaptotetrathiacalix[4]arene, H4(MTC[4]), with gold(I) phosphine units was investigated. Through deprotonation with NaOMe, followed by salt metathesis reactions with (PR3)AuCl (R=Me, Ph) complexes with two and three [(PR3)Au]+ moieties could be prepared and isolated, namely [(Ph3PAu)2H2(MTC[4])] and [(Me3PAu)3H(MTC[4])]. In [(Me3PAu)3H(MTC[4])] two gold atoms already come close enough to undergo aurophilic interactions. To introduce a fourth [(PR3)Au]+ entity TlOEt had to be used for the deprotonation, which led to the finding that four gold atoms organised by the (MTC[4])4− coordination platform are able to bind and stabilize a TlCl entity, yielding [(Me3PAu)4TlCl(MTC[4])]. As evidenced by structural and theoretical investigations the binding occurs through strong metallophilic interactions, which lead to photoluminescence at low temperatures.
N‐Doped Porous Carbon Derived from Solvent‐Free Synthesis of Cross‐Linked Triazine Polymers for Simultaneously Achieving CO2 Capture and Supercapacitors
Authors: Wang Yuan , Xiao Jianfei , Wang Hanzhi , Zhang Tian C. , Yuan Shaojun 
Published: March 2021

AbstractIt is highly desirable to design advanced heteroatomic doped porous carbon for wide application. Herein, N‐doped porous carbon (NPC) was developed via the fabrication of high nitrogen cross‐linked triazine polymers followed by pyrolysis and activation with controllable porous structure. The as‐synthesized NPC at the pyrolysis temperature of 700 °C possessed rich nitrogen content (up to 11.51 %) and high specific surface area (1353 m2 g−1), which led to a high CO2 adsorption capability at 5.67 mmol g−1 at 298.15 K and 5 bar pressure and excellent stability. When the activation temperature was at 600 °C, such NPC exhibited a superior electrochemical performance as anode for supercapacitors with a specific capacitance of 158.8 and 113 F g−1 in 6 M KOH at a current density of 1 and 10 A g−1, respectively. Notably, it delivered an excellent stability with capacity retention of 97.4 % at 20 A g−1after 6000 cycles.
Kinetic study of pyrolysis of high‐density polyethylene (HDPE) waste at different bed thickness in a fixed bed reactor
Authors: Li Haoyu , Mašek Ondřej , Harper Alan , Ocone Raffaella 
Published: March 2021

AbstractThe aim of this study is to investigate the kinetic characteristics of the high‐density polyethylene (HDPE) waste pyrolysis process based on thermogravimetric analysis (TGA) and using a fixed bed pyrolytic reactor (FBPR) at different temperatures. In addition, the influence of material bed thickness on the yield distribution and the composition of products was examined over a temperature range of 425–550°C. A higher wax fraction was obtained in the thin bed of the FBPR bed at 425°C. With temperature above 500°C, more oil and wax products were generated in the thick bed of the FBPR. Based on the experimental study, a discrete first‐order kinetic lumping model, comprising three independent parallel reactions (lumps), was developed to describe the yield distribution of gases, oil fractions, wax fractions, and solid residue, coupling with secondary cracking reactions of the wax fractions into lighter fractions (i.e., oil and gas). The overall apparent activation energy (Ea) and pre‐exponential factor (A0) of HDPE pyrolysis were estimated in the FBPR. The results showed that the thickness of the bed of plastics has a pronounced influence on the pyrolysis kinetics of HDPE.
Capacitive Impedance for Following In‐Situ Grafting Kinetics of Diazonium Salts
Authors: Shkirskiy Viacheslav , Levillain Eric , Gautier Christelle 
Published: March 2021

AbstractA new method to follow in‐situ grafting kinetics of diazonium compounds based on imposing small amplitude high frequency AC oscillations at grafting potential, is outlined. This enables the time‐resolved measurements of capacitive impedance concomitantly with the growth of the organic layer at the working electrode. The impedance values were quantitatively correlated with the ex‐situ (from voltammograms) and in‐situ (from quartz crystal microbalance) measured surface coverages, providing a validation of the new methodology. The versatility of the developed approach was demonstrated on the grafting via reduction of 4‐nitrobenzenediazonium on Au and glassy carbon (GC) substrates and via deposition of in‐situ generated diazonium salts from 1‐aminoanthraquinone and 4‐ferrocenylaniline on GC. The capacitive impedance measurements are simple, fast, and non‐destructive, making it an appealing methodology for an exploration of grafting kinetics of a wide range of diazonium salts.
Efficient Photocatalytic CO2 Reformation of Methane on Ru/La‐g‐C3N4 by Promoting Charge Transfer and CO2 Activation**
Authors: Li Naixu , Li Xianhe , Pan Rui , Cheng Miao , Guan Jie , Zhou Jiancheng , Liu Maochang , Tang Junwang , Jing Dengwei 
Published: March 2021

AbstractArtificial photosynthesis, in which solar energy drives CO2 to produce hydrocarbon fuels, is considered an effective way to solve the increasingly serious energy crisis and mitigate the greenhouse effect. Herein, layered porous Ru‐loaded and La‐doped g‐C3N4 nanosheets (Ru‐LGCNs) were prepared by one‐step calcination, followed by in situ photoreduction deposition of Ru. The layered Ru‐LGCN showed excellent photocatalytic CO2 reformation of methane performance under visible light, and the generation rates of CO, CH3CH3, CH3OH and CH3CH(OH)CH3 were 133, 154, 251 and 133 μmol h−1 g−1, respectively. The reason for the enhanced photocatalytic activity of Ru‐LGCN is the synergistic effect of bimetallic Ru and La. It is worth noting that the doped La can provide a good channel for charge transfer between LGCNs and CO2. This change in the charge behavior of the transport path is beneficial to break the C=O bonds on the active site La and generate methyl radicals on Ru, resulting in the generation of C2+ hydrocarbons.
Modification of Ti‐doped Hematite Photoanode with Quasi‐molecular Cocatalyst: A Comparison of Improvement Mechanism Between Non‐noble and Noble Metals
Authors: Wang Ruiling , Kuwahara Yasutaka , Mori Kohsuke , Qian Xufang , Zhao Yixin , Yamashita Hiromi 
Published: March 2021

AbstractLoading of molecular catalyst on the surface of semiconductors is an attractive way to boost the water oxidation activity. As active sites, molecular water oxidation cocatalysts show increasing attraction and application possibility. In order to compare the advantages between molecular catalysts with non‐noble and noble metals, the loading of the Fe(salen) and Ru(salen) as cocatalyst precursors on the surface of Ti−Fe2O3 was investigated Quasi‐Fe(salen) and Ru(salen) improved the photocurrent density by 1.5 and 1.7 times compared to that of the original Ti−Fe2O3 photoanode, respectively. The quasi‐Fe(salen) could improve the conductivity and reaction kinetics on the photoanode surface. By contrast, the notable advancements could be attributed to more reaction sites for quasi‐Ru(salen) as cocatalysts. Thus, non‐noble quasi‐Fe(salen) is a promising cocatalyst to replace the noble metal salen, and further optimization can be expected with regard to the precise control of reaction sites.
A novel soft‐switched interleaved high step‐up DC–DC converter for high‐efficiency conversion
Authors: Ghaffarpour Sadighi Hossein , Afjei Seyed Ebrahim , Salemnia Ahmad 
Published: March 2021

SummaryThe present study aims to present a new interleaved soft‐switched high step‐up DC–DC converter, which is suitable for renewable energy sources, by integrating built‐in transformer. A high conversion ratio is achieved by adjusting the turns ratio of the built‐in transformer and duty cycle. The proposed converter uses active clamped circuit, which provides zero‐voltage switching (ZVS) and a zero‐current switching (ZCS) operation for all switches and diodes, respectively. Therefore, the losses caused by reverse recovery are considerably alleviated by providing ZCS condition in the diodes. The proposed structure has some advantages such as low‐voltage stress across power switches, very low‐input current ripple, fewer components, and lower cost. The MOSFET with low drain‐source resistance can be used due to the low‐voltage stress, which could reduce conduction losses. Furthermore, a 500‐W, 48‐V input to 380‐V output laboratory prototype is built and tested to validate the performance of the proposed topology.
Optimal allocation of law enforcement patrol effort to mitigate poaching activities
Authors: Moore Jennifer F. , Udell Bradley J. , Martin Julien , Turikunkiko Ezechiel , Masozera Michel K. 
Published: March 2021

AbstractPoaching is a global problem causing the decline of species worldwide. Optimizing the efficiency of ranger patrols to deter poaching activity at the lowest possible cost is crucial for protecting species with limited resources. We applied decision analysis and spatial optimization algorithms to allocate efforts of ranger patrols throughout a national park. Our objective was to mitigate poaching activity at or below management risk targets for the lowest monetary cost. We examined this trade‐off by constructing a Pareto efficiency frontier using integer linear programming. We used data from a ranger‐based monitoring program in Nyungwe National Park, Rwanda. Our measure of poaching risk is based on dynamic occupancy models that account for imperfect detection of poaching activities. We found that in order to achieve a 5% reduction in poaching risk, 622 ranger patrol events (each corresponding to patrolling 1‐km2 sites) were needed within a year at a cost of US$49,760. In order to attain a 60% reduction in poaching risk, 15,560 patrol events were needed at a cost of US$1,244,800. We evaluated the trade‐off between patrol cost and poaching risk based on our model by constructing a Pareto efficiency frontier and park managers found the solution for a 50% risk reduction to be a practical trade‐off based on funding constraints (comparable to recent years) and the diminishing returns between risk mitigation and cost. This expected reduction in risk required 8,558 patrol events per year at a cost of US$684,640. Our results suggest that optimal solutions could increase efficiency compared to the actual effort allocations from 2006 to 2016 in Nyungwe National Park (e.g., risk reductions of ~30% under recent budgets compared to ~50% reduction in risk under the optimal strategy). The modeling framework in this study took into account imperfect detection of poaching risk as well as the directional and conditional nature of ranger patrol events given the spatial adjacency relationships of neighboring sites and access points. Our analyses can help to improve the efficiency of ranger patrols, and the modeling framework can be broadly applied to other spatial conservation planning problems with conditional, multilevel, site selection.
Bone quality assessed by trabecular bone score in severe anorexia nervosa: A brief report
Authors: Watters Ashlie , Fielding Linda , Mehler Philip S. 
Published: March 2021

AbstractObjectiveLow bone mineral density (BMD) in anorexia nervosa (AN) leads to increased risk of fractures. Debate exists whether to medicinally treat young patients with AN based on abnormal dual‐energy x‐ray absorptiometry (DXA) scores or to weight restore and reassess when older. Trabecular bone score (TBS), a technology measuring bone quality, is used in conjunction with DXA. This report explores the potential additional value of TBS, in adults with severe AN, to augment the DXA diagnostic information.MethodSeventy‐one DXA scans were reanalyzed to obtain TBS results from patients (mean age: 36.3 years). Differences in laboratory, anthropometric values and concomitant DXA measurements in relation to TBS results are reported.ResultsFor the cohort, mean body mass index (BMI) was 13.6 kg/m2 (SD: 2.1). The vast majority of patients had normal TBS with a mean of 1.395 (SD: 0.08) but, most patients (69%) had abnormal average DXA BMD Z‐scores of −2.2 (SD: 1.2). The patients who also demonstrated degraded bone quality on TBS had significantly lower percent ideal body weight and elevated alkaline phosphatase compared to patients with normal TBS (p's < .05).DiscussionLow BMD treatment decisions in AN may be optimized by considering both DXA and TBS results.
In Her Wake: On Blackness and Being on Our Own Terms
Authors: Daniel Barnes Riché J. 
Published: March 2021

AbstractIn this reflective piece, scholar Riché Barnes tacks back and forth between her own biography as it intertwined with the biography of Leith Mullings, who was her first graduate student advisor. As an anthropologist invested in Black feminist thought, Barnes explores what it means to live in the wake of Leith Mullings.
Suppression of NF‐κB‐induced chronic inflammation mitigates inflammatory osteolysis in the murine continuous polyethylene particle infusion model
Authors: Utsunomiya Takeshi , Zhang Ning , Lin Tzuhua , Kohno Yusuke , Ueno Masaya , Maruyama Masahiro , Huang Ejun , Rhee Claire , Yao Zhenyu , Goodman Stuart B. 
Published: March 2021

AbstractWear particle‐associated bone loss (periprosthetic osteolysis) constrains the longevity of total joint arthroplasty (TJA). Wear particles induce a prolonged upregulation of nuclear factor kappa B (NF‐κB) signaling in macrophages and osteoclasts. Synthetic double‐stranded oligodeoxynucleotides (ODNs) can prevent the binding of NF‐κB to the promoter regions of targeted genes and inhibit genetic activation. We tested the hypothesis that polyethylene‐particle induced chronic inflammatory bone loss could be suppressed by local delivery of NF‐κB decoy ODNs in murine in vivo model. Polyethylene particles were continuously infused into the medullary cavity of the distal femur for 6 weeks to induce chronic inflammation, and micro‐computational tomography and immunohistochemical analysis were performed. Particle‐induced chronic inflammation resulted in lower BMD values, an increase in osteoclastogenesis and nuclear translocation of p65, a prolonged M1 pro‐inflammatory macrophage phenotype, and a decrease of M2 anti‐inflammatory macrophage phenotype. Delayed timing of local infusion of NF‐κB decoy ODN for the last 3 weeks reversed polyethylene‐particle associated chronic inflammatory bone loss and facilitated bone healing. This study demonstrated that polyethylene‐particle associated chronic inflammatory osteolysis can be effectively modulated via interference with the NF‐κB pathway; this minimally invasive intervention could potentially be an efficacious therapeutic strategy for periprosthetic osteolysis after TJA.