bluuebunny/crossref_metadata_2025 huggingface dataset:
Recent Progress in Palladium‐Catalyzed Radical Reactions
Authors: Sun Xi , Dong Xu , Liu Hui , Liu Yuying
Published: January 2021

In recent years, great improvements have been made on palladium‐catalyzed radical reactions. Emerging elegant methodologies of radical involved palladium‐catalyzed transformations provide more and more effective strategies for the construction of complex heterocyclic compounds and applications in drug discovery. It is universally known that Pd(0)/(II)/(IV)‐mediated reactions usually undergo two‐electron transfer processes, while the Pd(I) and Pd(III) involved reactions usually occur via single electron transfer processes. Since our review on palladium radical was published, numurous methodolgies involving palladium radical have sprung up in the past five years. This review further summarized the up‐to‐date transformations toward palladium radical from 2015. For most of these catalytic cycles strategies, plausible mechanisms are demonstrated in detail to give better insight for chemists in need.

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Rh(III)‐Catalyzed Csp2−Csp3 Bond Cleavage/Carbonylethylation of α‐Indolyl Alcohols
Authors: Liu Zhipeng , Hu Xinwei , Yang Can , Xie Haisheng , Jiang Huanfeng , Zeng Wei
Published: January 2021

A Rh(III)‐catalyzed Csp2−Csp3 bond cleavage/carbonylethylation of α‐indolyl alcohols with allylic alcohols has been reported. This transformation involved a cascade C−C bond cleavage/C−C bond formation, and provides a novel approach to assemble 2‐carbonylethylindole skeletons.

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Visible Light‐Promoted Selenylation/Cyclization of Enaminones toward the Formation of 3‐Selanyl‐4H‐Chromen‐4‐Ones
Authors: Liu Hao‐Yang , Zhang Jia‐Rong , Huang Guo‐Bao , Zhou Yi‐Huan , Chen Yan‐Yan , Xu Yan‐Li
Published: January 2021

A simple and efficient visible‐light‐promoted selenylation/cyclization of enaminones have been realized for the practical synthesis of 3‐selanyl‐4H‐chromen‐4‐ones. This reaction is performed in the mild conditions, no transition metal catalyst or photocatalysts and no additional oxidants are required. In addition, the 3‐selanyl‐4H‐chromen‐4‐ones could be easily converted to selanyl‐functionalized pyrimidines by reacting with benzamidine substrates.

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Zirconium Oxide‐Catalyzed Direct Amidation of Unactivated Esters under Continuous‐Flow Conditions
Authors: Rashed Md. Nurnobi , Masuda Koichiro , Ichitsuka Tomohiro , Koumura Nagatoshi , Sato Kazuhiko , Kobayashi Shū
Published: January 2021

A sustainable and environmentally benign direct amidation reaction of unactivated esters with amines has been developed in a continuous‐flow system. A commercially available amorphous zirconium oxide was found to be an efficient catalyst for this reaction. While the typical amidation of esters with amines requires a stoichiometric amount of a promoter or metal activator, the present continuous‐flow method enabled the direct amidation reaction under additive‐free conditions with an extensive diversity towards various functional groups. High yields of the products were obtained with a nearly equimolar proportion of starting materials to reduce byproduct formation, which renders this process applicable for use in a sequential‐flow system.

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Nanoparticles as contrast agents for photoacoustic brain imaging
Authors: Liu Xingang , Duan Yukun , Liu Bin
Published: January 2021

Photoacoustic (PA) imaging has emerged as a promising technique for real‐time detection and diagnosis of brain‐related pathologies, due to its advantages in deep penetration of ultrasound imaging and high resolution of optical fluorescence imaging. We herein provide an overview on the latest developments of nanoparticles as contrast agents specifically designed for PA imaging of brain tumor, and brain vascular and other brain‐related diseases. Five design considerations of high‐performance PA contrast agents for brain‐related disease diagnosis are discussed, which include (1) strong absorption in NIR or NIR‐II window, (2) good biocompatibility, (3) high photothermal conversion efficiency, (4) precise nanostructure control, and (5) specific targeting capability. Challenges and perspectives of developing more robust and universal contrast agents for enhanced PA imaging are discussed at the end.
Modeling a fluidized bed reactor by integrating various scales: Pore, particle, and reactor
Authors: Macías Robert J. , Maya Juan C. , Chejne Farid , Afailal Z. , Arauzo J.
Published: January 2021

This work proposes a novel population‐balance based model for a bubbling fluidized bed reactor. This model considers two continuum phases: bubble and emulsion. The evolution of the bubble size distribution was modeled using a population balance, considering both axial and radial motion. This sub‐model involves a new mathematical form for the aggregation frequency, which predicts the migration of bubbles from the reactor wall toward the reactor center. Additionally, reacting particles were considered as a Lagrangian phase, which exchanges mass with emulsion phases. For each particle, the variation of the pore size distribution was also considered. The model presented here accurately predicted the experimental data for biochar gasification in a lab‐scale bubbling fluidized bed reactor. Finally, the aggregation frequency is shown to serve as a scaling parameter.
Mechanistic Understanding of Base‐Catalyzed Aldimine/Ketoamine Condensations: An Old Story and A New Model
Authors: Li Zhe‐wei , Zhang Lin , Pu Min , Lei Ming
Published: January 2021

Aldimine/ketoamine condensations are basic reactions in chemical synthesis. Herein a density functional theory (DFT) study was performed to characterize the mechanism of the ketoamine condensation of acetophenone with tert‐butanesulfinamide catalyzed by NaOH. The calculated results showed that the main N‐tert‐butanesulfinimines products own E configuration, which are due to both thermodynamic and kinetic effects. Meanwhile, the key roles of the substrate cage and the synergistic catalytic mode formed by metal cation and hydroxyl anion were pointed out, which imply the influence of noncovalent interactions on reaction activity. This theoretical study revealed the origin of E sulfinimines achieved in aldimine/ketoamine condensations catalyzed by base, which could provide new insights into the nature for the condensation reactions.
A dense sample of fossil primates (Adapiformes, Notharctidae, Notharctinae) from the Early Eocene Willwood Formation, Wyoming: Documentation of gradual change in tooth area and shape through time
Authors: O'Leary Maureen A.
Published: January 2021

Objectives

The Willwood Formation of the southern Bighorn Basin, Wyoming is a fluvial rock sequence that spans approximately 3 million years of early Eocene time. It has yielded one the largest collections of fossil mammals in the world including thousands of dentitions of extinct lemur‐like primates known as notharctines. In the southern Bighorn Basin, specimens of these primates have been collected on numerous paleontological expeditions and the stratigraphic levels yielding the dentitions have been carefully recorded. Notharctine dentitions represent a rare opportunity to study morphological variation in a single anatomical system through time among closely related individuals.

Materials and Methods

Prior studies of Bighorn Basin notharctines through time produced measurements of hundreds of specimens but I report here results from measurement and comparison of the dentitions and dentaries of more than 3,000 specimens, all stratigraphically mapped.

Results

Variation in premolar and molar area and variation in dentary depth are apparent throughout the section. Specimens with relatively small teeth and dentaries are known from the older part of the section. In younger rocks, variation in tooth area among specimens increases. Variation in tooth area is continuous and overlaps extensively both within and between stratigraphic levels. Other dental variables examined by inspection change in a mosaic and continuous fashion through the section. These features include variation in the presence and number of paraconids on the lower fourth premolar (p4), the size and shape of the entoconid notch on the lower first and second molars, and the relative development of the pseudohypocone, mesostyle, and cingula on the upper molars.

Discussion

These broad patterns can be identified despite notharctine alpha taxonomy being in need of extensive revision and, importantly, simplification. Such revision is beyond the scope of this article but is essential if we are to develop a taxonomy that is both free of stratigraphic influence and useful for rapid, repeatable species assignment. Boundaries among the patterns of tokogenesis, anagenesis, and cladogenesis are blurred in this dense sample of extinct primates. While pattern of evolution, a population‐level phenomenon, may be difficult to falsify in the fossil record, this notharctine sample suggests that in the rare instance such as this, when the fossil record is densely sampled, change through time is continuous and more consistent with gradual evolution.
Comparing semi‐landmarking approaches for analyzing three‐dimensional cranial morphology
Authors: Rolfe Sara , Davis Christopher , Maga A. Murat
Published: January 2021

Objectives

Increased use of three‐dimensional (3D) imaging data has led to a need for methods capable of capturing rich shape descriptions. Semi‐landmarks have been demonstrated to increase shape information but placement in 3D can be time consuming, computationally expensive, or may introduce artifacts. This study implements and compares three strategies to more densely sample a 3D image surface.

Materials and methods

Three dense sampling strategies: patch, patch‐thin‐plate spline (TPS), and pseudo‐landmark sampling, are implemented to analyze skulls from three species of great apes. To evaluate the shape information added by each strategy, the semi or pseudo‐landmarks are used to estimate a transform between an individual and the population average template. The average mean root squared error between the transformed mesh and the template is used to quantify the success of the transform.

Results

The landmark sets generated by each method result in estimates of the template that on average were comparable or exceeded the accuracy of using manual landmarks alone. The patch method demonstrates the most sensitivity to noise and missing data, resulting in outliers with large deviations in the mean shape estimates. Patch‐TPS and pseudo‐landmarking provide more robust performance in the presence of noise and variability in the dataset.

Conclusions

Each landmarking strategy was capable of producing shape estimations of the population average templates that were generally comparable to manual landmarks alone while greatly increasing the density of the shape information. This study highlights the potential trade‐offs between correspondence of the semi‐landmark points, consistent point spacing, sample coverage, repeatability, and computational time.
Giant Optical Activity and Second Harmonic Generation in 2D Hybrid Copper Halides
Authors: Guo Zhihang , Li Junzi , Wang Changshun , Liu Rulin , Liang Jiechun , Gao Yang , Cheng Jiaji , Zhang Wenjing , Zhu Xi , Pan Ruikun , He Tingchao
Published: January 2021

Hybrid organic–inorganic metal halides have emerged as highly promising materials for a wide range of applications in optoelectronics. Incorporating chiral organic molecules into metal halides enables the extension of their unique optical and electronic properties to chiral optics. By using chiral (R)‐ or (S)‐methylbenzylamine (R‐/S‐MBA) as the organic component, we synthesized chiral hybrid copper halides, (R‐/S‐MBA)2CuCl4, and investigated their optical activity. Thin films of this material showed a record anisotropic g‐factor as high as approximately 0.06. We discuss the origin of the giant optical activity observed in (R‐/S‐MBA)2CuCl4 by theoretical modeling based on density functional theory (DFT) and demonstrate highly efficient second harmonic generation (SHG) in these samples. Our study provides insight into the design of chiral materials by structural engineering, creating a new platform for chiral and nonlinear photonic device applications of the chiral hybrid copper halides.
Covalent Organic Frameworks Enabling Site Isolation of Viologen‐Derived Electron‐Transfer Mediators for Stable Photocatalytic Hydrogen Evolution
Authors: Mi Zhen , Zhou Ting , Weng Weijun , Unruangsri Junjuda , Hu Ke , Yang Wuli , Wang Changchun , Zhang Kai A. I. , Guo Jia
Published: January 2021

Electron transfer is the rate‐limiting step in photocatalytic water splitting. Viologen and its derivatives are able to act as electron‐transfer mediators (ETMs) to facilitate the rapid electron transfer from photosensitizers to active sites. Nevertheless, the electron‐transfer ability often suffers from the formation of a stable dipole structure through the coupling between cationic‐radical‐containing viologen‐derived ETMs, by which the electron‐transfer process becomes restricted. Herein, cyclic diquats, a kind of viologen‐derived ETM, are integrated into a 2,2′‐bipyridine‐based covalent organic framework (COF) through a post‐quaternization reaction. The content and distribution of embedded diquat‐ETMs are elaborately controlled, leading to the favorable site‐isolated arrangement. The resulting materials integrate the photosensitizing units and ETMs into one system, exhibiting the enhanced hydrogen evolution rate (34600 μmol h−1 g−1) and sustained performances when compared to a single‐module COF and a COF/ETM mixture. The integration strategy applied in a 2D COF platform promotes the consecutive electron transfer in photochemical processes through the multi‐component cooperation.
Chiral Near‐Infrared Fluorophores by Self‐Promoted Oxidative Coupling of Cationic Helicenes with Amines/Enamines
Authors: Bosson Johann , Labrador Geraldine M. , Besnard Céline , Jacquemin Denis , Lacour Jérôme
Published: January 2021

In one pot, tertiary alkyl amines are oxidized to enamines by cationic dioxa[6]helicene, which further reacts as electrophile and oxidant to form mono or bis donor‐π‐acceptor coupling products. This original and convergent synthetic approach provides a strong extension of conjugation yielding chromophores that absorb intensively in far‐red or NIR domains (λmax up to 791 nm) and fluoresce in the NIR as well (λmax up to 887 nm). Intense ECD properties around 790 nm with a |Δϵ| value up to 60 M−1 cm−1 are observed.
Ambient‐Stable Two‐Dimensional Titanium Carbide (MXene) Enabled by Iodine Etching
Authors: Shi Huanhuan , Zhang Panpan , Liu Zaichun , Park SangWook , Lohe Martin R. , Wu Yuping , Shaygan Nia Ali , Yang Sheng , Feng Xinliang
Published: January 2021

MXene (e.g., Ti3C2) represents an important class of two‐dimensional (2D) materials owing to its unique metallic conductivity and tunable surface chemistry. However, the mainstream synthetic methods rely on the chemical etching of MAX powders (e.g., Ti3AlC2) using hazardous HF or alike, leading to MXene sheets with fluorine termination and poor ambient stability in colloidal dispersions. Here, we demonstrate a fluoride‐free, iodine (I2) assisted etching route for preparing 2D MXene (Ti3C2Tx, T=O, OH) with oxygen‐rich terminal groups and intact lattice structure. More than 71 % of sheets are thinner than 5 nm with an average size of 1.8 μm. They present excellent thin‐film conductivity of 1250 S cm−1 and great ambient stability in water for at least 2 weeks. 2D MXene sheets with abundant oxygen surface groups are excellent electrode materials for supercapacitors, delivering a high gravimetric capacitance of 293 F g−1 at a scan rate of 1 mV s−1, superior to those made from fluoride‐based etchants (<290 F g−1 at 1 mV s−1). Our strategy provides a promising pathway for the facile and sustainable production of highly stable MXene materials.
Ultrafast Size Expansion and Turn‐On Luminescence of Atomically Precise Silver Clusters by Hydrogen Sulfide
Authors: He Wei‐Miao , Zhou Zhe , Han Zhen , Li Si , Zhou Zhan , Ma Lu‐Fang , Zang Shuang‐Quan
Published: January 2021

The formation of high‐nuclearity silver(I) clusters remains elusive and their potential applications are still underdeveloped. Herein, we firstly prepared a chain‐like thiolated AgI complex {[Ag18(StBu)10(NO3)8(CH3CN)2(H2O)2] ⋅ [Ag18(StBu)10(NO3)8(CH3CN)6]}n (abbreviated as Ag18) in which two similar Ag18 clusters are assembled by NO3− anions. The solution containing Ag18 reacted with hydrogen sulfide with controlled concentration, promptly producing another identifiable and bright red‐emitting high‐nuclearity silver(I) cluster, Ag62(S)13(StBu)32(NO3)4 (abbreviated as Ag62). We tracked the transformation using time‐dependent electrospray ionization mass spectrometry (ESI‐MS), UV/Vis absorption and photoluminescence spectra. Based on this cluster transformation, we further developed an ultra‐sensitive turn‐on sensor detecting H2S gas with an ultrafast response time (30 s) at a low detection limit (0.13 ppm). This work opens a new way of understanding the growth of metal clusters and developing their luminescent sensing applications.
Functional Neurological Symptom Disorder (Conversion Disorder) from an Interactional Approach: A Composite Case Study
Authors: Dennis Linda A.M. , Phipps Warwick D.
Published: January 2021

Functional neurological symptom disorder, alternatively termed conversion disorder (FNSD‐CD) (Although the DSM‐5 utilises the term 'conversion disorder', practitioners and consumers consider this to be an outdated, unsubstantiated and often stigmatising term. In accordance with this, the current terminology used in the field is 'functional neurological symptom disorder'), involves symptoms of altered voluntary motor or sensory functions without identifiable nervous system disease or pathology. It is considered a psychiatric disorder and is, thus, listed in the Diagnostic and Statistical Manual of Mental Disorders (5th Ed.; DSM‐5). As per the nosology of the DSM‐5, the discrete behavioural or psychological syndrome or pattern observed in FNSD‐CD is assumed to be a function of a problem of, or a disorder within, the individual. Accordingly, the psychiatric approach to FNSD‐CD, as set out in the DSM‐5, invokes an assumption common to the medical model which is that of lineal (i.e., straight‐line) causality, namely, causal events are arranged in a lineal sequence. The interactional approach, however, which is a development of general system theory in the field of family therapy, offers an alternative approach to understanding psychiatric disorders. Specifically, this approach places the emphasis on the relationships between individuals and their reciprocal influences on – including their psychological and emotional wellbeing with – one another. It draws on the assumption of nonlineal (i.e., circular) causality, namely, causal events are arranged in a circular sequence. From an interactional approach, therefore, FNSD‐CD is thought to be a function of a problem of, or a deficit within, the individuals’ relationship/s, rather than within an individual, per se. This article utilises a composite case study to investigate FNSD‐CD from an interactional approach.
Multiwalled carbon nanotubes/guanidine/Ni (II): A new and effective organometallic catalyst for the green synthesis of pyrazolopyranopyrimidines
Authors: Saeidiroshan Hakimeh , Moradi Leila
Published: January 2021

In this research, we report the first example of the use of multiwalled carbon nanotubes/guanidine/Ni (II) as a new and effective catalyst. The supported catalyst was prepared through a new method and characterized by Fourier transform infrared, scanning electron microscopy, energy‐dispersive spectroscopy, inductively coupled plasma, thermogravimetric analysis, ultraviolet diffuse reflectance spectroscopy, and transmission electron microscopy. Obtained catalyst was used for green and efficient synthesis of pyrazolopyranopyrimidines via four‐component reaction of hydrazine hydrate, ethyl acetoacetate, barbituric acid, and aromatic aldehydes under ultrasonic condition. All products were obtained in high yields and short reaction times. Also, the prepared catalyst was easily separated from the reaction mixture and reused for several times without significant loss of activity.
Feasibility of using polycarbonate as a substrate of thin film composite membrane in forward osmosis
Authors: Alihemati Z. , Hashemifard S. A. , Matsuura T. , Ismail A. F.
Published: January 2021

In the present study, thin film composite (TFC) forward osmosis (FO) membranes with polycarbonate (PC (and polyether sulfone (PES) as substrates were fabricated to investigate the impact of the structural parameters of substrate on the performance of the membranes. Firstly, the substrates were prepared by Loeb‐Sourirajan method. Characterization techniques including FESEM, contact angle measurement, pure water flux, gas permeability test, and tensile test were applied to investigate the properties of the substrates. After preparing suitable substrates, active layers were fabricated via interfacial polymerization (IP) technique. The performance and characterization test showed that PC is a relatively hydrophilic polymer with a good property for using as a substrate of FO TFC membrane but as the result of gas permeability test show, this membrane has large surface pore size in comparison with PES membrane. Mean pore size of PC and PES membrane is 378 and 139 nm, respectively. Also, the results show that the effective surface porosity of PC (285, 1/m) is more than PES (213, 1/m) substrate.
Preparation of high‐performance carbon nanotube/polyamide composite materials by elastic high‐shear kneading and improvement of properties by induction heating treatment
Authors: Noguchi Toru , Niihara Ken‐ichi , Kawamoto Keiichi , Fukushi Masanori , Jinnai Hiroshi , Nakajima Ken , Endo Morinobu
Published: January 2021

Polyamide 66 (PA66) nanocomposites were prepared by compounding carbon nanotubes (CNTs) using an elastic high‐shear kneading method, and the mechanism to understand their excellent properties was verified. In addition, we developed a microwave heat treatment that increases toughness quickly and at low cost. By combining 6.6 vol% or more of CNTs, PA66 with improved mechanical properties, such as higher elastic modulus and yield strength, was achieved, making it possible to obtain a composite having excellent high‐temperature characteristics that does not melt even at a temperature above the melting point. These effects appeared to be due to defibration of CNT aggregates and isolation and dispersion in PA66. A lamellar crystal of PA66 grows around the CNT, forming an interphase. The higher performance appeared to be attributable to a continuous three‐dimensional structure in which CNTs are bound via the interphase, and the improvement of the elastic modulus of the composite material was tentatively ascribed to a Halpin‐Tsai model in which the size of the unit cell of the three‐dimensional structure is introduced. The resulting CNT/PA66 composite materials are superior not only in performance but also in price.
Young people's information practices in library makerspaces
Authors: Li Xiaofeng
Published: January 2021

While there have been a growing number of studies on makerspaces in different disciplines, little is known about how young people interact with information in makerspaces. This study aimed to unpack how young people (middle and high schoolers) sought, used, and shared information in voluntary free‐choice library makerspace activities. Qualitative methods, including individual interviews, observations, photovoice, and focus groups, were used to elicit 21 participants' experiences at two library makerspaces. The findings showed that young people engaged in dynamic practices of information seeking, use, and sharing, and revealed how the historical, sociocultural, material, and technological contexts embedded in makerspace activities shaped these information practices. Information practices of tinkering, sensing, and imagining in makerspaces were highlighted. Various criteria that young people used in evaluating human sources and online information were identified as well. The study also demonstrated the communicative and collaborative aspects of young people's information practices through information sharing. The findings extended Savolainen's everyday information practices model and addressed the gap in the current literature on young people's information behavior and information practices. Understanding how young people interact with information in makerspaces can help makerspace facilitators and information professionals better support youth services and facilitate makerspace activities.
An iSchool approach to data science: Human‐centered, socially responsible, and context‐driven
Authors: Shah Chirag , Anderson Theresa , Hagen Loni , Zhang Yin
Published: January 2021

The Information Schools, also referred to as iSchools, have a unique approach to data science with three distinct components: human‐centeredness, socially responsible, and rooted in context. In this position paper, we highlight and expand on these components and show how they are integrated in various research and educational activities related to data science that are being carried out at iSchools. We argue that the iSchool way of doing data science is not only highly relevant to the current times, but also crucial in solving problems of tomorrow. Specifically, we accentuate the issues of developing insights and solutions that are not only data‐driven, but also incorporate human values, including transparency, privacy, ethics, fairness, and equity. This approach to data science has meaningful implications on how we educate the students and train the next generation of scholars and policymakers. Here, we provide some of those design decisions, rooted in evidence‐based research, along with our perspective on how data science is currently situated and how it should be advanced in iSchools.
Investigative approaches to researching information technology companies
Authors: Carter Daniel , Acker Amelia , Sholler Dan
Published: January 2021

Recent events reveal the potential for information technologies to threaten democratic participation and destabilize knowledge institutions. These are core concerns for researchers working within the area of critical information studies—yet these companies have also demonstrated novel tactics for obscuring their operations, reducing the ability of scholars to speak about how harms are perpetuated or to link them to larger systems. While scholars' methods and ethical conventions have historically privileged the agency of research participants, the current landscape suggests the value of exploring methods that would reveal actions that are purposefully hidden. We propose investigation as a model for critical information studies and review the methods and epistemological conventions of investigative journalists as a provocative example, noting that their orientation toward those in power enables them to discuss societal harms in ways that academic researchers often cannot. We conclude by discussing key topics, such as process accountability and institutional norms, that should feature in discussions of how academic researchers might position investigation in relation to their own work.
An overview on the conversion of glycerol to value‐added industrial products via chemical and biochemical routes
Authors: Lima Paula Jéssyca Morais , da Silva Rhonyele Maciel , Neto Carlos Alberto Chaves Girão , Gomes e Silva Natan Câmara , Souza José Erick da Silva , Nunes Yale Luck , Sousa dos Santos José Cleiton
Published: January 2021

Glycerol is a common by‐product of industrial biodiesel syntheses. Due to its properties, availability, and versatility, residual glycerol can be used as a raw material in the production of high value‐added industrial inputs and outputs. In particular, products like hydrogen, propylene glycol, acrolein, epichlorohydrin, dioxalane and dioxane, glycerol carbonate, n‐butanol, citric acid, ethanol, butanol, propionic acid, (mono‐, di‐, and triacylglycerols), cynamoil esters, glycerol acetate, benzoic acid, and other applications. In this context, the present study presents a critical evaluation of the innovative technologies based on the use of residual glycerol in different industries, including the pharmaceutical, textile, food, cosmetic, and energy sectors. Chemical and biochemical catalysts in the transformation of residual glycerol are explored, along with the factors to be considered regarding the choice of catalyst route used in the conversion process, aiming at improving the production of these industrial products.
Aktive Verbinder für Bauelemente aus Carbonbeton
Authors: Ayoubi Mazen , Sobotta Sacha , Schlüter Dominik , Michler Harald , Kropp Thomas , Thüsing Kai , Kallnick Stefanie , Schumann Alexander
Published: January 2021

Die Umsetzung einer modularen, vorgefertigten Bauweise sowie der weitreichende Einsatz von Leichtbauelementen aus Carbon‐ oder Textilbeton verlangen neue Verbindungselemente. Bauteile aus Carbonbeton werden wesentlich schlanker als vergleichbare Stahlbetonelemente ausgeführt. Neben den geometrischen Bedingungen für die Verbindung stellt insbesondere die Kraftübertragung in entsprechend dünnen Elementen eine Herausforderung für Planer und Bauausführung dar. Eine nachhaltige, modulare Bauweise benötigt darüber hinaus Verbindungselemente, die eine einfache und sichere Montage einzelner Elemente ermöglichen und die Ästhetik des Bauwerks nicht beeinflussen. In diesem Aufsatz werden für genau diesen Anwendungsfall innovative Verbindungselemente vorgestellt, die auf Basis von Formgedächtnislegierungen (FGL) funktionieren. Die neuen Verbindungskonzepte streben eine deutliche Vereinfachung der Montage auf der Baustelle an. Durch den Einsatz von Memory‐Stahl als aktives Verbindungselement kann auf eine mechanische Zugänglichkeit zur Verbindung verzichtet werden. In diesem Beitrag werden das primäre Anwendungsfeld der FGL‐Verbinder sowie die ersten Konzepte und Entwicklungen aufgezeigt.
Dämpfungskennwerte des Schotteroberbaus auf Eisenbahnbrücken
Authors: Stollwitzer Andreas , Fink Josef
Published: January 2021

Um die Eigenschaften des Schotteroberbaus in dynamischen Berechnungen von Eisenbahnbrücken zu berücksichtigen, steht in der Brückendynamik zwar ein breites Feld an Rechenmodellen zur Verfügung, eine erhebliche Streuung der zugehörigen Steifigkeits‐ und Dämpfungskennwerte erschwert jedoch einen ingenieurpragmatischen Zugang. Aufbauend auf dynamischen Analysen an einer Versuchsanlage, welche durch ihre spezielle Funktionsweise eine Betrachtung des vom Brückentragwerk unabhängigen Schotteroberbaus ermöglicht, werden Dämpfungskennwerte für den Schotteroberbau bestimmt. Die Kennwerte sind dabei zugehörig zu einem mechanischen Modell, welches auf die im Schotteroberbau wirkenden Energiedissipations‐ bzw. Dämpfungsmechanismen abgestimmt ist und eine Gleis‐Tragwerk‐Interaktion sowohl in horizontaler als auch in vertikaler Richtung berücksichtigt. Die ermittelten Dämpfungskennwerte zeigen für das gegenständliche Versuchsspektrum signifikante Frequenz‐, Verschiebungs‐ und Beschleunigungsabhängigkeiten, unterliegen innerhalb dieser Abhängigkeiten jedoch nur einer geringfügigen Streuung, womit für den Schotteroberbau letztendlich eine ausreichend genaue und realitätsnahe Angabe von Rechenmodell und darauf abgestimmten Kennwerten ermöglicht wird.
Parent‐conducted rapid assessment of attention types for the treatment of attention‐maintained problem behavior
Authors: Livingston Cynthia , Adams Molly B. , Strohmeier Craig W.
Published: January 2021

When praise is not a reinforcer for alternative behavior in the treatment of attention‐maintained problem behavior, further pretreatment assessments are warranted to develop an effective treatment. The current study reports a replication of the pretreatment rapid assessment of attention types (RAAT) procedures, implemented by the parents of a 19‐year‐old female with attention‐maintained problem behavior. After administering staff and parent‐conducted RAATs, a parent‐implemented treatment, (a) produced clinically significant decreases in problem behavior, and (b) confirmed that the RAAT identified an attention‐type that served as a reinforcer for appropriate alternative behavior. This study extends the findings of Strohmeier et al. by reporting results of a parent‐conducted RAAT and treatment evaluation. The findings highlight the practical importance of pretreatment assessment of attention‐types, with emphasis on caregiver involvement, to develop effective treatments for attention‐maintained problem behavior.
Lyophilization stabilizes clinical‐stage core‐crosslinked polymeric micelles to overcome cold chain supply challenges
Authors: Ojha Tarun , Hu Qizhi , Colombo Claudio , Wit Jan , van Geijn Michiel , van Steenbergen Mies J. , Bagheri Mahsa , Königs‐Werner Hiltrud , Buhl Eva Miriam , Bansal Ruchi , Shi Yang , Hennink Wim E. , Storm Gert , Rijcken Cristianne J. F. , Lammers Twan
Published: January 2021

Background

CriPec technology enables the generation of drug‐entrapped biodegradable core‐crosslinked polymeric micelles (CCPM) with high drug loading capacity, tailorable size, and drug release kinetics. Docetaxel (DTX)‐entrapped CCPM, also referred to as CPC634, have demonstrated favorable pharmacokinetics, tolerability, and enhanced tumor uptake in patients. Clinical efficacy evaluation is ongoing. CPC634 is currently stored (shelf life > 5 years) and shipped as a frozen aqueous dispersion at temperatures below −60°C, in order to prevent premature release of DTX and hydrolysis of the core‐crosslinks. Consequently, like other aqueous nanomedicine formulations, CPC634 relies on cold chain supply, which is unfavorable for commercialization. Lyophilization can help to bypass this issue.

Methods and results

Freeze‐drying methodology for CCPM was developed by employing CPC634 as a model formulation, and sucrose and trehalose as cryoprotectants. We studied the residual moisture content and reconstitution behavior of the CPC634 freeze‐dried cake, as well as the size, polydispersity index, morphology, drug retention, and release kinetics of reconstituted CPC634. Subsequently, the freeze‐drying methodology was validated in an industrial setting, yielding a CPC634 freeze‐dried cake with a moisture content of less than 0.1 wt%. It was found that trehalose‐cryoprotected CPC634 could be rapidly reconstituted in less than 5 min at room temperature. Critical quality attributes such as size, morphology, drug retention, and release kinetics of trehalose‐cryoprotected freeze‐dried CPC634 upon reconstitution were identical to those of non‐freeze‐dried CPC634.

Conclusion

Our findings provide proof‐of‐concept for the lyophilization of drug‐containing CCPM and our methodology is readily translatable to large‐scale manufacturing for future commercialization.
Generation of enzymatically competent SARS‐CoV‐2 decoy receptor ACE2‐Fc in glycoengineered Nicotiana benthamiana
Authors: Castilho Alexandra , Schwestka Jennifer , Kienzl Nikolaus F. , Vavra Ulrike , Grünwald‐Gruber Clemens , Izadi Shiva , Hiremath Chaitra , Niederhöfer Janine , Laurent Elisabeth , Monteil Vanessa , Mirazimi Ali , Wirnsberger Gerald , Stadlmann Johannes , Stöger Eva , Mach Lukas , Strasser Richard
Published: January 2021

Human angiotensin‐converting enzyme 2 (ACE2) is the primary host cell receptor for severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) binding and cell entry. Administration of high concentrations of soluble ACE2 can be utilized as a decoy to block the interaction of the virus with cellular ACE2 receptors and potentially be used as a strategy for treatment or prevention of coronavirus disease 2019. Human ACE2 is heavily glycosylated and its glycans impact on binding to the SARS‐CoV‐2 spike protein and virus infectivity. Here, we describe the production of a recombinant soluble ACE2‐fragment crystallizable (Fc) variant in glycoengineered Nicotiana benthamiana. Our data reveal that the produced dimeric ACE2‐Fc variant is glycosylated with mainly complex human‐type N‐glycans and functional with regard to enzyme activity, affinity to the SARS‐CoV‐2 receptor‐binding domain, and wild‐type virus neutralization.
Process development and optimization of continuous capture with three‐column periodic counter‐current chromatography
Authors: Shi Ce , Zhang Qi‐Lei , Jiao Biao , Chen Xu‐Jun , Chen Ran , Gong Wei , Yao Shan‐Jing , Lin Dong‐Qiang
Published: January 2021

Continuous capture with affinity chromatography is one of the most important units for continuous manufacturing of monoclonal antibody (mAb). Due to the complexity of three‐column periodic counter‐current chromatography (3C‐PCC), three approaches (experimental, model‐based, and simplified approaches) were studied for process development and optimization. The effects of residence time for interconnected load (RT
C), breakthrough percentage of the first column for interconnected load (s) and feed protein concentration (c
0) on productivity and capacity utilization were focused. The model‐based approach was found superior to the experimental approach in process optimization and evaluation. Two phases of productivity were observed and the optimal RT
C for the maximum productivity was located at the boundary of the two phases. The comprehensive effects of the operating parameters (RT
C, s, and c
0) were evaluated by the model‐based approach, and the operation space was predicted. The best performance of 34.5 g/L/h productivity and 97.6% capacity utilization were attained for MabSelect SuRe LX resin under 5 g/L concentration at RT
C = 2.8 min and s = 87.5%. Moreover, a simplified approach was suggested to obtain the optimal RT
C for the maximum productivity. The results demonstrated that model‐assisted tools are useful to determine the optimum conditions for 3C‐PCC continuous capture with high productivity and capacity utilization.
Reversible Control of Gelatin Hydrogel Stiffness by Using DNA Crosslinkers**
Authors: Buchberger Alex , Saini Harpinder , Eliato Kiarash Rahmani , Zare Azadeh , Merkley Ryan , Xu Yang , Bernal Julio , Ros Robert , Nikkhah Mehdi , Stephanopoulos Nicholas
Published: January 2021

Biomaterials with dynamically tunable properties are critical for a range of applications in regenerative medicine and basic biology. In this work, we show the reversible control of gelatin methacrylate (GelMA) hydrogel stiffness through the use of DNA crosslinkers. We replaced some of the inter‐GelMA crosslinks with double‐stranded DNA, allowing for their removal through toehold‐mediated strand displacement. The crosslinks could be restored by adding fresh dsDNA with complementary handles to those on the hydrogel. The elastic modulus (G’) of the hydrogels could be tuned between 500 and 1000 Pa, reversibly, over two cycles without degradation of performance. By functionalizing the gels with a second DNA strand, it was possible to control the crosslink density and a model ligand in an orthogonal fashion with two different displacement strands. Our results demonstrate the potential for DNA to reversibly control both stiffness and ligand presentation in a protein‐based hydrogel, and will be useful for teasing apart the spatiotemporal behavior of encapsulated cells.
Structure Dependent Product Selectivity for CO2 Electroreduction on ZnO Derived Catalysts
Authors: Han Kai , Ngene Peter , de Jongh Petra
Published: January 2021

Electrochemical conversion of CO2 is an attractive alternative to releasing it to the atmosphere. Catalysts derived from electroreduction of metal oxides are often more active than when starting with metallic phase catalyst. The origin of this effect is not yet clear. Using ZnO nanorods, we show that the initial structure of the oxide as well as the electrolyte medium have a profound impact on the structure of the catalytic active Zn phase, and thereby the selectivity of the catalysts. ZnO nanorods with various aspect ratios were electrochemically reduced in different electrolytes leading to metallic Zn with different structures; a sponge‐like structure, nanorods and nanoplates. The sponge‐like Zn produced syngas with H2 : CO=2, and some formate, the nanorods produced only syngas with H2 : CO=1, while Zn nanoplates exhibited 85 % selectivity towards CO. These results open a pathway to design new electrocatalysts with optimized properties by modifying the structure of the starting material and the electroreduction medium.
Natural and Synthetic Oligoarylamides: Privileged Structures for Medical Applications
Authors: Seedorf Tim , Kirschning Andreas , Solga Danny
Published: January 2021

The term “privileged structure” refers to a single molecular substructure or scaffold that can serve as a starting point for high‐affinity ligands for more than one receptor type. In this report, a hitherto overlooked group of privileged substructures is addressed, namely aromatic oligoamides, for which there are natural models in the form of cystobactamids, albicidin, distamycin A, netropsin, and others. The aromatic and heteroaromatic core, together with a flexible selection of substituents, form conformationally well‐defined scaffolds capable of specifically binding to conformationally well‐defined regions of biomacromolecules such as helices in proteins or DNA often by acting as helices mimics themselves. As such, these aromatic oligoamides have already been employed to inhibit protein–protein and nucleic acid–protein interactions. This article is the first to bring together the scattered knowledge about aromatic oligoamides in connection with biomedical applications.
Photohomolysis and Photoheterolysis in Aryl Sulfonates and Aryl Phosphates
Authors: Bonesi Sergio , Protti Stefano , Fagnoni Maurizio
Published: January 2021

The photochemical behaviour of selected aryl sulfonates and phosphates (ArOX) in polar and nonpolar media has been investigated by laser flash photolysis (LFP) experiments. Two main pathways have been identified, namely the photohomolysis of the ArO−X bond or the photoheterolysis of the Ar−OX bond depending on the nature of the leaving group (OX) and on the nature of the substituents on the aromatic ring. In nonpolar solvents the esters are quite photostable due to an efficient triplet deactivation. In polar solvents, the homolytic fragmentation of the ArO−S bond from the exited singlets was found in aryl sulfonates bearing moderately electron‐donating groups as well as electron‐withdrawing groups. In electron‐rich aryl phosphates and sulfonates photoheterolysis of the Ar−OP/Ar−OS bond took place as the exclusive pathway.
Intermolecular Hydroaminoalkylation of Alkynes
Authors: Kaper Tobias , Fischer Malte , Thye Hermann , Geik Dennis , Schmidtmann Marc , Beckhaus Ruediger , Doye Sven
Published: January 2021

Intermolecular hydroaminoalkylation reactions of alkynes with secondary amines, which selectively give access to allylic amines with E configuration of the alkene unit, are achieved in the presence of titanium catalysts. Successful reactions of symmetrically substituted diaryl‐ and dialkylalkynes as well as a terminal alkyne take place with N‐benzylanilines, N‐alkylanilines, and N‐alkylbenzylamines.
Automated segmentation algorithm with deep learning framework for early detection of glaucoma
Authors: Natarajan Deepa , Sankaralingam Esakkirajan , Balraj Keerthiveena , Thangaraj Veerakumar
Published: January 2021

Early stage of diagnosis of eye diseases through automatic analysis in the retinal image is the emerging technology in the area of retinopathy. Glaucoma is the primary reason for the loss of visibility in people around the world. The separation of the disc and the cup in the optic region is the technique used to identify glaucoma in the human retinal image. In this paper, superpixel segmentation, followed by Modified Kernel Fuzzy C‐Means (MKFCM) algorithm is used to segment the optic disc and optic cup. The proposed segmentation method achieves a maximum average of F‐score as 0.979, an average boundary distance as 10.016 pixels, and an average correlation coefficient of 0.949. To train convolutional neural networks (CNN), the segmented images obtained by the MKFCM segmentation algorithm is given as the input for the identification of glaucoma. This CNN uses the gray level co‐occurrence matrix features calculated from the segmented image. The experiment used for this study demonstrates that CNN gives superior categorization correctness and requires fewer figures of knowledge iterations than the original CNN. The accuracy obtained by this proposed method is 94.2%. The model will help to identify the proper class of severity of glaucoma in retinal images.
An Androsterone‐H2@C60hybrid: Synthesis, Properties and Molecular Docking Simulations with SARS‐Cov‐2
Authors: Suárez Margarita , Makowski Kamil , Lemos Reinier , Almagro Luis , Rodríguez Hortensia , Herranz María Ángeles , Molero Dolores , Ortiz Orlando , Maroto Enrique , Albericio Fernando , Murata Yasujiro , Martín Nazario
Published: January 2021

We report the synthesis and characterization of a fullerene‐steroid hybrid that contains H2@C60and a dehydroepiandrosterone moiety synthesized by a cyclopropanation reaction with 76 % yield. Theoretical calculations at the DFT‐D3(BJ)/PBE 6‐311G(d,p) level predict the most stable conformation and that the saturation of a double bond is the main factor causing the upfield shielding of the signal appearing at −3.13 ppm, which corresponds to the H2located inside the fullerene cage. Relevant stereoelectronic parameters were also investigated and reinforce the idea that electronic interactions must be considered to develop studies on chemical‐biological interactions. A molecular docking simulation predicted that the binding energy values for the protease‐hybrid complexes were −9.9 kcal/mol and −13.5 kcal/mol for PLproand 3CLprorespectively, indicating the potential use of the synthesized steroid‐H2@C60as anti‐SARS‐Cov‐2 agent.
A Novel AKR1C3 Specific Prodrug TH3424 With Potent Antitumor Activity in Liver Cancer
Authors: He Ping , Wang Chunnian , Wang Yanlan , Wang Caiyan , Zhou Changhua , Cao Donglin , Li Jiang , Bushnell David A. , Li Qing , Kornberg Roger D. , Xie Wei , Wang Zhong
Published: January 2021

Overexpression of AKR1C3, an aldo‐keto reductase, was recently discovered in liver cancers. In this study, an inverse correlation between AKR1C3 expression and survival of patients with liver cancer was observed. AKR1C3 inhibitors, however, failed to suppress liver cancer cell growth. The prodrug TH3424, which releases a DNA alkylating reagent upon reduction by AKR1C3, was developed to target tumors with overexpression of AKR1C3. TH3424 showed specific killing of liver cancer cells with AKR1C3 overexpression both in vitro and in vivo. In patient‐derived mouse xenograft models, TH3424 at doses as low as 1.5 mg/kg eliminated liver tumors with no apparent toxicity. Therefore, TH3424 is a promising drug candidate for liver cancer and other types of cancers overexpressing AKR1C3.
Interface Engineering of Needle‐Like P‐Doped MoS2/CoP Arrays as Highly Active and Durable Bifunctional Electrocatalyst for Overall Water Splitting
Authors: Hu Yan , Yu Hongbo , Qi Luoluo , Dong Jiaxin , Yan Puxuan , Taylor Isimjan Tayirjan , Yang Xiulin
Published: January 2021

Developing a bifunctional water splitting catalyst with high efficiency and low cost are crucial in the electrolysis water industry. Here, we report a rational design and simple preparation method of MoS2‐based bifunctional electrocatalyst on carbon cloth (CC). The optimized P‐doped MoS2@CoP/CC catalyst presents low overpotentials for the hydrogen (HER) and oxygen evolution reactions (OER) of 64 and 282 mV in alkaline solution as well as 72 mV HER overpotential in H2SO4 at a current density of 10 mA cm−2. Furthermore, P‐MoS2@CoP/CC as a bifunctional catalyst delivered relatively low cell voltages of 1.83 and 1.97 V at high current densities of 500 and mA cm−2 in 30 % KOH. The two‐electrode system showed a remarkable stability for 30 h, even outperformed the benchmark RuO2||Pt/C catalyst. The excellent electrochemical performance can be credited to the unique microstructure, high surface area, and the synergy between metal species. This study presents a possible alternative for noble metal‐based catalysts to overcome the challenges of industrial applications.