bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrahigh Brightness Carbon Dot–Based Blue Electroluminescent LEDs by Host–Guest Energy Transfer Emission Mechanism
Authors: Xu Jiacong , Miao Yanqin , Zheng Jingxia , Yang Yongzhen , Liu Xuguang
Published: April 2018

Ultrahigh brightness blue carbon dot–based light‐emitting diodes (CD‐LEDs) are fabricated by a host–guest doping method with poly(N‐vinylcarbazole) (PVK) as the host to realize the high brightness and pure emission of CD‐LEDs. Oleophylic CDs are synthesized as the dopant to obtain a wide range of doping concentration of CDs because oleophylic CDs and PVK can be well cosoluble in chlorobenzene at any doping concentration. Therefore, the CD‐LEDs emitting pure blue light that dominantly originates from CDs' emission are realized by optimizing the doping concentration. A host–guest energy transfer is the main emission mechanism for CDs. It is observed that CD‐LED also achieves a maximum luminance of 569.8 cd m−2, which is the highest luminance compared with ever reported blue CD‐LEDs.
A simple method for preparation of microcellularPLA/calcium carbonate nanocomposite using super critical nitrogen as a blowing agent: Control of microstructure
Authors: Mahdavi Mina , Yousefzade Omid , Garmabi Hamid
Published: April 2018

A simple method was used to prepare microcellular foams of poly(lactic acid) (PLA) and its nanocomposites to improve its shortcomings such as low impact resistance and high cost. The batch foaming process of purePLAandPLAfilled with Nano calcium carbonate (NCC) was conducted using supercritical nitrogen (N2) as a blowing agent. The effect ofNCCon crystallization ofPLAis discussed as a remarkable parameter in foaming of semicrystalline polymers. Differential scanning calorimetry (DSC) was used to optimize the process temperature. The effect of foaming conditions (temperature, pressure, and cooling rate) and nanoparticle content on the foam microstructure ofPLAand its nanocomposites were investigated using scanning electron microscopy (SEM). Foams were obtained in the range of macro‐ and microscale (different cell sizes) using different foaming conditions. The results revealed that nanoparticles show excellent nucleation performance onPLAfoaming. Results of dynamic mechanical thermal analysis (DMTA) also showed significant influences ofNCCon foamed and prefoamed samples to different foaming structures.
Moss protonemata are dispersed by water, wind, and snails
Authors: Pasiche‐Lisboa Carlos J. , Jesús Inés Sastre‐De
Published: April 2018

Premise of the Study

Mosses produce asexual propagules, which are dispersed, thus allowing population establishment and maintenance. However, it is unknown if or how protonemata—one of their asexually produced propagules—are dispersed. Moss protonemata were exposed to three dispersal vectors (water, wind, and snails) to describe the dispersal capability and survival after dispersal.

Methods

The protonemata of mosses Callicostella belangeriana and Taxiphyllum taxirameum were splashed with water drops from a 1 or 2 m height, exposed to two wind velocities (V1 = 2.74 mps and V2 = 3.76 mps), and fed to terrestrial snails. Dispersal of protonemata was described for wind and water by studying the dispersal distance and the relationships between protonemata sizes and dispersal distances. Survival after dispersal was recorded for the three vectors.

Key Results

Water and wind dispersed protonemata up to 80 and 265.5 cm, respectively. The protonemata dispersed the farthest distance when splashed by 2 m drops and hit by V2 wind velocities. No, or little, relationship between protonemata size and dispersal distance was found for the water and wind vectors. Protonemata survived and became established after dispersal: survival was high when dispersed by water and snails, but was low for wind.

Conclusions

For the first time, it was shown that protonemata are dispersed mostly close to the source, which is suggested to aid in moss population maintenance.
Laboratory testing in BCR‐ABL1‐like (Philadelphia‐like) B‐lymphoblastic leukemia/lymphoma
Authors: Siegele Bradford J. , Nardi Valentina
Published: April 2018

BCR‐ABL1‐like B‐lymphoblastic leukemia/lymphoma (BCR‐ABL1‐like B‐ALL), also known as Philadelphia‐like (Ph‐like) ALL, is a neoplasm of B‐lineage lymphoblasts characterized by a pattern of gene expression similar to that of B‐ALL with the BCR‐ABL1 translocation but lacking the BCR‐ABL1 fusion protein. The diagnosis of BCR‐ABL1‐like B‐ALL is associated with a high rate of relapse and poor clinical outcomes. In recognition of the difficulty in screening these leukemias for diagnostic workup, the 2016 update/revision to the World Health Organization (WHO) 2008 edition included BCR‐ABL1‐like B‐ALL as a provisional entity. This review addresses the various clinical considerations and methodologies currently used in the pathologic diagnosis, subclassification, and molecular characterization of cases of BCR‐ABL1‐like B‐ALL, with particular attention paid to emerging methods useful in identification of molecular lesions potentially amenable to targeted therapy.
Functional independence of Taiwanese children with Prader–Willi syndrome
Authors: Lee Chung‐Lin , Lin Hsiang‐Yu , Tsai Li‐Ping , Chiu Huei‐Ching , Tu Ru‐Yi , Huang You‐Hsin , Chien Yin‐Hsiu , Lee Ni‐Chung , Niu Dau‐Ming , Chao Mei‐Chyn , Tsai Fuu‐Jen , Chou Yen‐Yin , Chuang Chih‐Kuang , Lin Shuan‐Pei
Published: April 2018

Prader–Willi syndrome (PWS) is a genetic disorder with obesity, developmental delay, short stature, and behavioral abnormalities. The study aimed to assess the functional independence in children with PWS. The Functional Independence Measure for Children (WeeFIM) was used to evaluate 81 children with PWS (44 boys and 37 girls) with a median age of 11 years 1 month (range 2 years 8 months to 20 years 2 months) were recruited between January 2013 and December 2016. The mean total WeeFIM score was 103.8 (maximum 126). Sixty‐five patients (80%) had deletion type PWS, 16 (20.0%) had nondeletion type. The scores were 103.6 ± 18.5 for deletion and 104.8 ± 18.3 for nondeletion type (p = .405), 104.8 ± 19.3 in boys and 102.6 ± 17.3 in girls (p = .293). The mean self‐care, mobility, and cognition scores were 47 (maximum 56), 33 (maximum 35), and 24 (maximum 35), respectively. All total scores and 18 subscores in the three functional domains were positively correlated with age (p < .05). Most children required assistance in problem‐solving, comprehension, and expression. The WeeFIM identified the strengths and limitations of children with PWS and confirmed that support and supervision were needed in cognitive and self‐care tasks.
Expanding the phenotype of congenital central hypoventilation syndrome impacts management decisions
Authors: Byers Heather M. , Chen Maida , Gelfand Andrew S. , Ong Bruce , Jendras Marisa , Glass Ian A.
Published: April 2018

Congenital central hypoventilation syndrome (CCHS) is a neurocristopathy caused by pathogenic heterozygous variants in the gene paired‐like homeobox 2b (PHOX2B). It is characterized by severe infantile alveolar hypoventilation. Individuals may also have diffuse autonomic nervous system dysfunction, Hirschsprung disease and neural crest tumors. We report three individuals with CCHS due to an 8‐base pair duplication in PHOX2B; c.691_698dupGGCCCGGG (p.Gly234Alafs*78) with a predominant enteral and neural crest phenotype and a relatively mild respiratory phenotype. The attenuated respiratory phenotype reported here and elsewhere suggests an emergent genotype:phenotype correlation which challenges the current paradigm of invoking mechanical ventilation for all infants diagnosed with CCHS. Best treatment requires careful clinical judgment and ideally the assistance of a care team with expertise in CCHS.
Cascade Claisen Rearrangement: Rapid Synthesis of Polysubstituted Salicylaldehydes and Total Syntheses of Hemigossypol and Gossypol
Authors: Cao Tongxiang , Kong Yi , Luo Kui , Chen Lianfen , Zhu Shifa
Published: April 2018

A cascade Claisen rearrangement of a well‐organized maltol propargyl ether for the construction of polysubstituted salicylaldehydes is reported. This reaction features high atom economy (100 %), as well as catalyst‐free and gram‐scale conditions. Based on this novel methodology, the total synthesis of hemigossypol, gossypol, and their analogues has been realized.
Zur Photochemie von Künstlerfarben: Strategien zur Verhinderung von Farbveränderungen in Kunstwerken
Authors: Miliani Costanza , Monico Letizia , Melo Maria J. , Fantacci Simona , Angelin Eva M. , Romani Aldo , Janssens Koen
Published: April 2018

Die Absorption von Licht verleiht Pigmenten ihre Farbe – und damit den Grund ihrer Existenz –, erzeugt aber auch angeregte Zustände, d. h. neue Moleküle mit einem Energieüberschuss, der über Abbauwege dissipiert werden kann. Photoabbauprozesse rufen langfristige, kumulierte und irreversible Farbveränderungen hervor (Verblassung, Dunklung, Ausbleichung), deren Prognose und Verhinderung schwierige Herausforderungen darstellen. Von all den Umweltrisiken, die Kulturgüter beeinträchtigen, ist Lichteinfall das einzige, das nicht ohne Auswirkungen auf die optimale Präsentation des Ausstellungsstücks reguliert werden kann. Lichtinduzierte Veränderungen betreffen nicht nur die Pigmente selbst, sondern auch ihre Wechselwirkungen mit dem Trägermaterial und Bindemittel und werden selbst wiederum durch die Umgebungsbedingungen verkompliziert. In diesem Kurzaufsatz untersuchen wir, wie Chemie (insbesondere in Form mehrskaliger analytischer Studien von Kunstwerken), Computermodellierung und physikalische/chemische Studien dazu beitragen können, die ursprünglichen Erscheinungsbilder von Kunstwerken zu rekonstruieren und wirksame Konservierungsstrategien zu etablieren.
In Vitro Reconstitution of OxyC Activity Enables Total Chemoenzymatic Syntheses of Vancomycin Aglycone Variants
Authors: Forneris Clarissa C. , Seyedsayamdost Mohammad R.
Published: April 2018

The bioactivity of vancomycin is enabled by three aromatic crosslinks, the biosynthesis of which has been an active area of investigation for two decades. Two cytochrome P450 enzymes, OxyB and OxyA, have been shown to introduce bisaryl ether linkages with the help of a so‐called X‐domain. The final crosslink, however, a biaryl bond thought to be installed by OxyC, has remained elusive. We report the in vitro reconstitution of the OxyC reaction and formation of the first carbon–carbon crosslink in any glycopeptide antibiotic. Using a cascade sequence, in which the peptide substrate was incubated with the Oxy enzymes in turn, we completed the chemoenzymatic synthesis of a vancomycin aglycone variant. This approach was also used to generate a new analogue carrying a thioamide linkage at residue 4, a precursor to the amidine derivative, which is effective against vancomycin‐resistant pathogens. Our results set the stage for creating therapeutic vancomycin derivatives by using the native metalloenzymes.
Synthesis, Structure, Bonding, and Reactivity of Metal Complexes Comprising Diborane(4) and Diborene(2): [{Cp*Mo(CO)2}2{μ‐η2:η2‐B2H4}] and [{Cp*M(CO)2}2B2H2M(CO)4], M=Mo,W
Authors: Mondal Bijan , Bag Ranjit , Ghorai Sagar , Bakthavachalam K. , Jemmis Eluvathingal D. , Ghosh Sundargopal
Published: April 2018

The reaction of [(Cp*Mo)2(μ‐Cl)2B2H6] (1) with CO at room temperature led to the formation of the highly fluxional species [{Cp*Mo(CO)2}2{μ‐η2:η2‐B2H4}] (2). Compound 2, to the best of our knowledge, is the first example of a bimetallic diborane(4) conforming to a singly bridged Cs structure. Theoretical studies show that 2 mimics the Cotton dimolybdenum–alkyne complex [{CpMo(CO)2}2C2H2]. In an attempt to replace two hydrogen atoms of diborane(4) in 2 with a 2e [W(CO)4] fragment, [{Cp*Mo(CO)2}2 B2H2W(CO)4] (3) was isolated upon treatment with [W(CO)5⋅thf]. Compound 3 shows the intriguing presence of [B2H2] with a short B−B length of 1.624(4) Å. We isolated the tungsten analogues of 3, [{Cp*W(CO)2}2B2H2W(CO)4] (4) and [{Cp*W(CO)2}2B2H2Mo(CO)4] (5), which provided direct proof of the existence of the tungsten analogue of 2.
Maximizing the Number of Interfacial Sites in Single‐Atom Catalysts for the Highly Selective, Solvent‐Free Oxidation of Primary Alcohols
Authors: Li Tianbo , Liu Fei , Tang Yan , Li Lin , Miao Shu , Su Yang , Zhang Junying , Huang Jiahui , Sun Hui , Haruta Masatake , Wang Aiqin , Qiao Botao , Li Jun , Zhang Tao
Published: April 2018

The solvent‐free selective oxidation of alcohols to aldehydes with molecular oxygen is highly attractive yet challenging. Interfacial sites between a metal and an oxide support are crucial in determining the activity and selectivity of such heterogeneous catalysts. Herein, we demonstrate that the use of supported single‐atom catalysts (SACs) leads to high activity and selectivity in this reaction. The significantly increased number of interfacial sites, resulting from the presence of individually dispersed metal atoms on the support, renders SACs one or two orders of magnitude more active than the corresponding nanoparticle (NP) catalysts. Lattice oxygen atoms activated at interfacial sites were found to be more selective than O2 activated on metal NPs in oxidizing the alcohol substrate. This work demonstrates for the first time that the number of interfacial sites is maximized in SACs, providing a new avenue for improving catalytic performance by developing appropriate SACs for alcohol oxidation and other reactions occurring at metal–support interfacial sites.
Light‐Induced Reversible Reconfiguration of DNA‐Based Constitutional Dynamic Networks: Application to Switchable Catalysis
Authors: Wang Shan , Yue Liang , Li Zi‐Yuan , Zhang Junji , Tian He , Willner Itamar
Published: April 2018

The light‐induced reversible and cyclic reconfiguration of constitutional dynamic networks, consisting of supramolecular nucleic acid structures as constituents and a photoisomerizable trans/cis‐azobenzene‐functionalized nucleic acid as the trigger is demonstrated. In addition, the cyclic photochemical reconfiguration of the constitutional dynamic networks guides the switchable on/off operation of an emerging hemin/G‐quadruplex DNAzyme.
The Discovery of a Palladium(II)‐Initiated Borono‐Catellani Reaction
Authors: Chen Shuqing , Liu Ze‐Shui , Yang Tao , Hua Yu , Zhou Zhiyu , Cheng Hong‐Gang , Zhou Qianghui
Published: April 2018

Reported is a novel palladium(II)‐initiated Catellani‐type reaction that utilizes widely accessible aryl boronic acids as the substrates instead of aryl halides, thereby greatly expanding the existing scope of this powerful transformation. This borono‐Catellani reaction was promoted by cooperative catalysis between Pd(OAc)2 and the inexpensive 5‐norbornene‐2‐carbonitrile. Practicality is the striking feature of the reaction: it is run open to air at ambient temperature and no phosphine ligand is needed. This mild, chemoselective, and scalable protocol is compatible with a large range of readily available functionalized aryl boronic acids and bromides, as well as terminating olefins (50 examples, 39–97 % yields). Moreover, the orthogonal reactivity between the borono‐Catellani and classical Catellani reaction was demonstrated. This work is expected to open new avenues for developing novel Catellani‐type reactions.
Copper‐Catalyzed Heteroarylboration of 1,3‐Dienes with 3‐Bromopyridines: A cine Substitution
Authors: Smith Kevin B. , Huang Yuan , Brown M. Kevin
Published: April 2018

A method for the heteroarylboration of 1,3‐dienes is presented. The process involves an unusual cine substitution of 3‐bromopyridine derivatives to deliver highly functionalized heterocyclic products. Mechanistic studies are included that clarify the details of this unusual process.
1,4‐Iron Migration for Expedient Allene Annulations through Iron‐Catalyzed C−H/N−H/C−O/C−H Functionalizations
Authors: Mo Jiayu , Müller Thomas , Oliveira João C. A. , Ackermann Lutz
Published: April 2018

C−H activation bears great potential for enabling sustainable molecular syntheses in a step‐ and atom‐economical manner, with major advances having been realized with precious 4d and 5d transition metals. In contrast, we employed earth abundant, nontoxic iron catalysts for versatile allene annulations through a unique C−H/N−H/C−O/C−H functionalization sequence. The powerful iron catalysis occurred under external‐oxidant‐free conditions even at room temperature, while detailed mechanistic studies revealed an unprecedented 1,4‐iron migration regime for facile C−H activations.
In Situ Generation of Silylzinc by Si−B Bond Activation Enabling Silylzincation and Silaboration of Terminal Alkynes
Authors: Nagashima Yuki , Yukimori Daiki , Wang Chao , Uchiyama Masanobu
Published: April 2018

A new protocol has been designed for the in situ generation of unstable Si−Zn species through the reaction of dialkylzinc, phosphine, and silylborane (Si−B). Successive reactions with various terminal alkynes using this protocol enabled highly controllable regio‐/stereo‐/chemoselective silylzincation and silaboration on demand without the need for a transition‐metal catalyst.
Directional Shuttling of a Stimuli‐Responsive Cone‐Like Macrocycle on a Single‐State Symmetric Dumbbell Axle
Authors: Cui Jie‐Shun , Ba Qian‐Kai , Ke Hua , Valkonen Arto , Rissanen Kari , Jiang Wei
Published: April 2018

Rotaxane‐based molecular shuttles are often operated using low‐symmetry axles and changing the states of the binding stations. A molecular shuttle capable of directional shuttling of an acid‐responsive cone‐like macrocycle on a single‐state symmetric dumbbell axle is now presented. The axle contains three binding stations: one symmetric di(quaternary ammonium) station and two nonsymmetric phenyl triazole stations arranged in opposite orientations. Upon addition of an acid, the protonated macrocycle shuttles from the di(quaternary ammonium) station to the phenyl triazole binding station closer to its butyl groups. This directional shuttling presumably originates from charge repulsion and an orientational binding preference between the cone‐like cavity and the nonsymmetric phenyl triazole station. This mechanism for achieving directional shuttling by manipulating only the wheels instead of the tracks is new for artificial molecular machines.
Unmanned Aerial Vehicles Formation Using Learning Based Model Predictive Control
Authors: Hafez Ahmed T. , Givigi Sidney N. , Yousefi Shahram
Published: April 2018

This paper presents a solution for the formation flight problem for multiple unmanned aerial vehicles (UAVs) cooperating to execute a required mission. Learning Based Model Predictive Control (LBMPC) is implemented on the team of UAVs in order to accomplish the required formation. All flight simulations respect Reynold's rules of flocking to avoid UAV collisions with nearby flockmates, match the team members velocity and stay close to each other during the formation. The main contribution of this paper lies in the application of LBMPC to solve the problem of formation for an autonomous team of UAVs. The proposed solution is theoretically, by the application of analysis to the problem, demonstrated to be stable. Moreover, simulations support the findings of the paper. The main contributions of this paper are the proposed LBMPC formulation for formation of vehicles with uncertainty in their models, and the theoretical analysis of the solution.
Recombinant AroL‐Catalyzed Phosphorylation for the Efficient Synthesis of Shikimic Acid 3‐Phosphate
Authors: Schoenenberger Bernhard , Wszolek Agata , Meier Roland , Brundiek Henrike , Obkircher Markus , Wohlgemuth Roland
Published: April 2018

Shikimic acid 3‐phosphate, as a central metabolite of the shikimate pathway, is of high interest as enzyme substrate for 5‐enolpyruvoyl‐shikimate 3‐phosphate synthase, a drug target in infectious diseases and a prime enzyme target for the herbicide glyphosate. As the important substrate shikimic acid 3‐phosphate is only accessible via a chemical multi‐step route, a new straightforward preparative one‐step enzymatic phosphorylation of shikimate using a stable recombinant shikimate kinase has been developed for the selective phosphorylation of shikimate in the 3‐position. Highly active shikimate kinase is produced by straightforward expression of a synthetic aroL gene in Escherichia coli. The time course of the shikimate kinase‐catalyzed phosphorylation is investigated by 1H‐ and 31P‐NMR, using the phosphoenolpyruvate/pyruvate kinase system for the regeneration of the ATP cofactor. This enables the development of a quantitative biocatalytic 3‐phosphorylation of shikimic acid. After a standard workup procedure, a good yield of shikimic acid 3‐phosphate, with high HPLC‐ and NMR purity, is obtained. This efficient biocatalytic synthesis of shikimic acid 3‐phosphate is superior to any other method and has been successfully scaled up to multi‐gram scale.
The quantitative assessment of epicardial fat distribution on human hearts: Implications for epicardial electrophysiology
Authors: Mattson Alexander R. , Soto Mario J. , Iaizzo Paul A.
Published: April 2018

Epicardial electrophysiological procedures rely on dependable interfacing with the myocardial tissue. For example, epicardial pacing systems must generate sustainable chronic pacing capture, while epicardial ablations must effectively deliver energy to the target hyper‐excitable myocytes. The human heart has a significant adipose layer which may impede epicardial procedures. The objective of this study was to quantitatively assess the relative location of epicardial adipose on the human heart, to define locations where epicardial therapies might be performed successfully. We studied perfusion‐fixed human hearts (n = 105) in multiple isolated planes including: left ventricular margin, diaphragmatic surface, and anterior right ventricle. Relative adipose distribution was quantitatively assessed via planar images, using a custom‐generated image analysis algorithm. In these specimens, 76.7 ± 13.8% of the left ventricular margin, 72.7 ± 11.3% of the diaphragmatic surface, and 92.1 ± 8.7% of the anterior right margin were covered with superficial epicardial adipose layers. Percent adipose coverage significantly increased with age (P < 0.001) and history of coronary artery disease (P < 0.05). No significant relationships were identified between relative percent adipose coverage and gender, body weight or height, BMI, history of hypertension, and/or history of congestive heart failure. Additionally, we describe two‐dimensional probability distributions of epicardial adipose coverage for each of the three analysis planes. In this study, we detail the quantitative assessment and probabilistic mapping of the distribution of superficial epicardial adipose on the adult human heart. These findings have implications relative to performing epicardial procedures and/or designing procedures or tools to successfully perform such treatments. Clin. Anat. 31:661–666, 2018. © 2018 Wiley Periodicals, Inc.
Web‐mediated problem‐based learning and computer programming: Effects of thinking style on academic achievement and attitude
Authors: Yağcı Mustafa
Published: April 2018

The present study aims to investigate the effect of the thinking styles on students’ attitudes toward problem based learning, web based learning and academic achievement within an online problem‐based learning environment. In this study, a single‐factor, pre‐test post‐test single group and semi empirical pattern was utilized. The study was conducted on 41 students from a public university in Turkey. To implement problem‐based learning activities, a teaching environment was designed with the Moodle platform, allowing for group work and discussions. Six status of the problems were prepared exclusively for the 10‐week application period so that students could make suggestions about how to solve them. In the data collection phase, the Scale of Thinking Styles, the Attitude toward Problem Based Learning Scale, the Attitude toward Web Based Learning Scale, and the Academic Achievement Test were employed. T‐test and covariance analyses were carried out in the statistical analysis phase. According to the findings of the present study, the Elaborator, and the Extrovert students have a more positive view of problem based learning than the Integrator and the Introvert students. Furthermore, the Elaborator and the Innovative students have a more positive view of web based learning than the Integrator and the Traditionalist students. Moreover, it was determined that the Elaborator and the Innovative students were more successful than the Integrator and the Traditionalist students. As a result, students’ thinking styles are related to attitude and academic achievement.
Four Natural Compounds Separated from Folium Isatidis: Crystal Structures and Antibacterial Activity
Authors: Liao Bei‐Ling , Pan Yu‐Jie , Zhang Wei , Pan Li‐Wei
Published: April 2018

Four natural compounds were obtained by concentrating, separating and purifying from the Folium isatidis. These natural compounds have been characterized by elemental analysis, IR spectrum, NMR and single‐crystal X‐ray diffraction analysis. The results show that these natural compounds are 4(3H)‐quinazolinone (I), 2,4(1H,3H)‐quinazolinedione (II), methyl 3,4‐dihydro‐4‐oxoquinazoline‐2‐carboxylate (III) and ethyl 3,4‐dihydro‐4‐oxoquinazoline‐2‐carboxylate (IV). The antibacterial activity experiment showed that I and II had better activity against Staphylococcus aureus, Escherichia coli, Bacillus subtilis and Salmonella than III, IV and other multiple components, because III and IV have long branches and steric hindrance effect. Compounds I and II have planar structure, which can more easily combine with these bacteria and kill them. The above results have good guiding significance for studying the antibacterial activity for single components or mixtures from natural origin.
Anaerobic Radical Enzymes for Biotechnology
Authors: Jäger Christof M. , Croft Anna K.
Published: April 2018

Enzymes that proceed through radical intermediates have a rich chemistry that includes functionalization of otherwise unreactive carbon atoms, carbon‐skeleton rearrangements, aromatic reductions, and unusual eliminations. Especially under anaerobic conditions, organisms have developed a wide range of approaches for managing these transformations that can be exploited to generate new biological routes towards both bulk and specialty chemicals. These routes are often either much more direct or allow access to molecules that are inaccessible through standard (bio)chemical approaches. This review gives an overview of some of the key enzymes in this area: benzoyl‐CoA reductases effecting the enzymatic Birch reduction, ketyl radical dehydratases, coenzyme B12‐dependent enzymes, glycyl radical enzymes, and radical SAM (AdoMet radical) enzymes. These enzymes are discussed alongside biotechnological applications, highlighting the wide range of actual and potential uses. With the increased diversity in biotechnological approaches to obtaining these enzymes and information about them, even more of these enzymes can be expected to find application in industrial processes.
DL‐3‐n‐butylphthalide promotes dendrite development in cortical neurons subjected to oxygen‐glucose deprivation/reperfusion
Authors: Zhang Peng , Xu Ruxiang , Guo Yang , Qin Jiazhen , Dai Yiwu , Liu Ning , Wu Cuiying
Published: April 2018

The limited degree of functional recovery is closely associated with the condition of the periinfarct cortex after ischemic stroke. The model of oxygen‐glucose deprivation in cultured neurons could partly simulate this condition. Proper dendritic morphology is crucial for the correct wiring of neuronal function. Hence, the question of how to facilitate the plasticity of neural dendrites is of great significance. DL‐3‐n‐butylphthalide is an efficient medication for ischemic stroke. In this study, in addition to having neuroprotective effects, DL‐3‐n‐butylphthalide could increase the number of primary and secondary dendrites and of dendritic tips as confirmed by Sholl analysis. This study further demonstrated that DL‐NBP inactivates PI3K/AKT signaling to positively regulate dendritic branching.
Exchange Interactions Switch Tunneling: A Comparative Experimental and Theoretical Study on Relaxation Dynamics by Targeted Metal Ion Replacement
Authors: Tian Haiquan , Ungur Liviu , Zhao Lang , Ding Shuai , Tang Jinkui , Chibotaru Liviu F.
Published: April 2018

The magnetic relaxation and magnetization blocking barriers of tailor‐made homo‐ and heterodinuclear compounds [Dy2(opch)2(OAc)2(H2O)2]⋅MeOH (1) and [DyMn(opch)2(OAc)(MeOH)(H2O)2] (2), where H2opch is (E)‐N′‐(2‐hydroxy‐3‐methoxybenzylidene)pyrazine‐2‐carbohydrazide, were systematically investigated and the change in single‐molecule magnet behavior originating from targeted replacement of one dysprosium site in the Dy2 compound with manganese was elucidated through a combination of experimental and theoretical studies. A detailed comparative study on these closely related model compounds revealed remarkable changes of the crystal‐field splitting and anisotropy of the Dy site and the total exchange spectrum due to the replacement of Dy by Mn. The blocking barriers of these two compounds, which explain their different relaxation behaviors, were analyzed. The two Ising doublets arising from the magnetic interaction in the case of 1 are strongly uniaxial, with tunneling splittings smaller than 10−6 cm−1, and this leads to magnetic relaxation at temperatures exceeding the exchange energy (2.14 cm−1), which involves transition via the excited states corresponding to local transitions on the excited doublet at the Dy site. The third and fourth exchange doublets in 2 (located at 2.16 and 3.25 cm−1, respectively) show much larger tunneling splittings (of 10−4 and 10−3 cm−1, respectively), and thus open an important path for magnetic relaxation.
Modelling the Hydrothermal Ageing of a Fe‐Zeolite Catalyst for Automotive NH3‐SCR Applications
Authors: Ruggeri Maria Pia , Nova Isabella , Tronconi Enrico , Schmeißer Volker , Weibel Michel
Published: April 2018

The effects of duration and temperature of hydrothermal ageing treatments were investigated on a commercial Fe‐zeolite catalyst for NH3‐SCR addressing NH3 adsorption, NH3 oxidation, and NH3 reaction with NOx. Hydrothermal ageing affected primarily NH3 oxidation and standard SCR activities, as well as NH3 storage capacity. Deactivation was fast in the first few hours, eventually approaching asymptotic levels. There is potential to predict the effects of hydrothermal ageing on the SCR behavior of Fe‐zeolite catalysts as a function of just one parameter, i.e., the NH3 storage capacity.
Numerical investigation of heterogeneous nucleation of water vapour on PM10 for particulate abatement
Authors: Fan Fengxian , Zhang Sihong , Peng Zhengbiao , Chen Jun , Su Mingxu , Moghtaderi Behdad , Doroodchi Elham
Published: April 2018

A heterogeneous nucleation model with inclusions of the line tension effect, the particle roughness effect, and the surface diffusion mechanism was presented. Effects of the particle roughness and the wetting agent on the heterogeneous nucleation behaviour were examined. The scaled nucleation barrier was analyzed and subsequently implications of the nucleation behaviour in the particulate abatement by vapour condensation were discussed. It was found that the effect of particle roughness on the nucleation behaviour was greatly affected by the line tension. There existed an optimal concentration of wetting agent at which the lowest nucleation barrier and critical saturation ratio could be obtained. The surface diffusion mechanism played an overwhelmingly important role in governing the embryo growth for hydrophilic particles with a diameter Dp > 0.1 µm and an embryo size smaller than the critical size, otherwise the contribution of direct vapour deposition mechanism could be significant. Based on the scaled nucleation barrier, three distinct nucleation regimes, i.e. athermal heterogeneous nucleation, thermal heterogeneous‐dominant nucleation, and homogeneous‐dominant nucleation, have been identified. When the contact angle was large, the wetting agent might need to be added to reduce the contact angle so as to reach the athermal heterogeneous and thermal heterogeneous‐dominant nucleation regimes, thus achieving efficient particulate abatement at low cost. The prediction results matched reasonably with the experimental data.
Extraction of macauba kernel oil using supercritical carbon dioxide and compressed propane
Authors: Trentini Caroline Portilho , Cuco Roberta Pazinato , Cardozo‐Filho Lucio , Silva Camila da
Published: April 2018

Macauba kernel oil (MKO) was extracted using supercritical CO2 and compressed propane as the solvent. The influence of temperature (313–353 K for CO2 and 303–333 K for propane) and pressure (18–22 MPa for CO2 and 8–12 MPa for propane) on oil yield was investigated, and the results were compared with conventional extraction. A characterization of oil and defatted meal was performed. Temperature and pressure, in the evaluated range, influenced oil yield with the use of CO2. For propane, the oil yield was not influenced by the experimental conditions. In the evaluated experimental range, the use of propane and CO2 provided 100 % and ∼93 % oil yield compared to conventional extraction, respectively. MKO showed a predominance of saturated fatty acids, among which lauric acid was the major constituent. CO2 presented greater efficiency in the removal of phytosteroids and tocopherols from the macauba kernel, however, the oil extracted with propane presented longer oxidative stability. Defatted meals presented modified physico‐chemical composition and potentiated technological characteristics due to oil removal.
Evolution of Graphene Oxide and Graphene: From Imagination to Industrialization
Authors: Tiwari Santosh K. , Mishra Raghvendra Kumar , Ha Sung Kyu , Huczko Andrzej
Published: April 2018

During the past 32years, more than 103000 research articles with term graphene in the title or in manuscript have been recorded in the Scopus database. This exceptional reputation of graphene is due to numerous reasons; the most significant one appears to be its incomparable physical properties, resulting in real‐time application in many fields of science and technology. That's why it seems to be absolutely justified that “graphene possesses everything's what you want”. This article is a tribute to the researchers who contributed to the background of the current face of graphene. In this short paper we are presenting the contributions of initial research articles on graphite that are responsible for the present status of graphene and led the research interests of materials scientists toward the potential applications of graphene and its derivatives. The current progress in graphene research output of renowned scientists around the globe is also evaluated based on the Scopus and Web of Science databases. However, a particular emphasis is focused on the current technological innovations (2010–2017) based on graphene, as well as mostly prototype devices fabricated using graphene as a key material along with discussing the recent challenges in graphene nanotechnology, and a recommendation of the ways to advance the commercial readiness of the products based on graphene and their derivatives. In addition, we have also briefly discussed the limitations of graphene, future prospects and present global market trends of graphene‐based products.
Mechanochemistry in [6]Cycloparaphenylene: A Combined Raman Spectroscopy and Density Functional Theory Study
Authors: Qiu Lili , Peña‐Alvarez Miriam , Baonza Valentín G. , Taravillo Mercedes , Casado Juan , Kertesz Miklos
Published: April 2018

Raman spectroscopy under high pressures up to 10 GPa and density functional computations up to 30 GPa are combined to obtain insights into the behavior of a prototypical nanohoop conjugated molecule, [6]cycloparaphenylene ([6]CPP). Upon increasing pressure, the nanohoop undergoes deformations, first reversible ovalization and then at even higher pressures aggregates are formed. This irreversible aggregation is caused by the formation of new intermolecular σ‐bonds. Frequencies and derivatives of the Raman frequency shifts as a function of pressure are well reproduced by the computations. The frequency behavior is tied to changes in aromatic/quinonoid character of the nanohoop. The modeling at moderate high pressures reveals the deformation of the [6]CPP molecules into oval‐like and peanut‐like shapes. Surprisingly the pressure derivatives of the observed Raman mode shifts undergo a sudden change around a pressure value that is common to all Raman modes, indicating an underlying geometrical change extended over the whole molecule that is interpreted by the computational modeling. Simulations predict that under even larger deformations caused by higher pressures, oligomerization reactions would be triggered. Our simulations demonstrate that these transformations would occur regardless of the solvent, however pressures at which they happen are influenced by solvent molecules encapsulated in the interior of the [6]CPP.
Fear Conditioning by Proxy: Social Transmission of Fear Between Interacting Conspecifics
Authors: Jones Carolyn E. , Agee Laura , Monfils Marie‐H.
Published: April 2018

We describe a method of social fear transmission to a discrete auditory cue in freely behaving rats. Extending beyond traditional observer/demonstrator paradigms, rats are allowed to physically interact and integrate cues from all sensory modalities. In the protocol described in this article, “observer” rats experience social fear conditioning through a proxy cage mate that serves as a “demonstrator” during retrieval of a cued fear memory. We find that a specific auditory cue can come to elicit fear expression in an animal with no foot shock experience simply by interacting with a conspecific expressing a conditioned response in the presence of an otherwise benign stimulus. In this “fear conditioning by proxy” paradigm, we have demonstrated that some, but not all, rats display conditioned responding (e.g., freezing) to a cue after interacting with a cage mate during fear memory retrieval. The amount of freezing exhibited by this fear conditioned “by proxy” rat 24 hr after learning critically depends on social influences, including social relationships and social interactions during learning. © 2018 by John Wiley & Sons, Inc.
Harnessing the Potential of Emerging Digital Health and Biological Sampling Technologies for Clinical Drug Development: Promise to Reality
Authors: Kothare Prajakti A. , Jadhav Pravin R. , Gupta Pankaj , Harrelson Jane Croft , Dickmann Leslie
Published: April 2018

Advances in emerging innovative technologies have led to optimistic outlooks on their transformative potential for healthcare and clinical trials.1 Given the increased attention, this white paper by the International Consortium for Innovation and Quality in Pharmaceutical Development (IQ) presents perspectives on pharmaceutical and biotechnology industry trends for innovative digital health, adherence, and outpatient sampling technologies. As stimulus for cross‐company scientific dialog points to consider for adoption, implementation, and recommendations to broaden uptake are proposed.
Photooxidation of Fulvenes in a Continuous Flow Photoreactor using Carbon Dioxide as a Solvent
Authors: Wu Lingqiao , Lee Darren S. , Boufroura Hamza , Poliakoff Martyn , George Michael W.
Published: April 2018

A range of 3‐substituted oxepinones have been synthesised by the photooxidation of fulvenes with photochemically generated singlet oxygen (1O2) using carbon dioxide (CO2) as a solvent and a CO2‐soluble porphyrin photosensitizer. The reactive intermediates generated in this reaction decompose to yield a range of useful and underutilized building blocks that are not easily accessible using more traditional reaction setups. Fulvenes containing an exocyclic allylic hydrogen are shown to form three products through potentially competing intramolecular pathways, which can be tuned to some extent by adjusting the conditions in the flow reactor. A range of substrates containing a variety of functional groups was examined; this led to lower yields of the desired lactones being observed in the case of compounds containing polar electron‐donating groups. We also demonstrate that one of the lactones can be further hydrogenated over a Pd/C catalyst to the unsaturated 7‐membered ring in high yield.
Self‐Assembled Metal Zinc Three‐Dimensional Microstructures at Room Temperature
Authors: Song Limin , liu Dan , Zhang Shujuan
Published: April 2018

Three‐dimensional metal zinc (Zn) with the shapes of like‐flower, like‐grass, and like‐urchin are successfully prepared by a convenient method that replaced zinc cations (Zn2+) with metal magnesium (Mg) plate at room temperature. The as‐prepared microstructures are investigated by X‐ray diffraction and scanning electron microscopy. The morphology of Zn microstructures is affected by both solvents and anions. The conditions of the self‐assembly of variable shapes are clarified. The formation mechanism of various microstructures is also deduced in detail. The method herein is advantageous in convenience, low cost, and environmental benignity.
On the efficient simulation of electrical circuits with constant phase elements: The Warburg element as a test case
Authors: Athanasiou Vasileios , Konkoli Zoran
Published: April 2018

The constant phase Element (CPE) concept naturally emerges as a model for describing a range of electrical phenomena where ionic diffusion is involved. We suggest a new method for modelling the transient behavior of electrical circuits that contain CPE elements. Without loss of generality, we study the Warburg element to demonstrate the method, but the method can be easily extended to any CPE. Transient simulations of such elements require the numerical evaluation of a computationally expensive convolution integral that links the voltage drop across the element, with the current that passed through it. In our work we suggest a new method for reducing the computational cost of the numerical evaluation of the convolution integral. We show that the computational cost can be reduced by one order of magnitude.
Adaptive management of animal populations with significant unknowns and uncertainties: a case study
Authors: Gerber Brian D. , Kendall William L.
Published: April 2018

Conservation and management decision making in natural resources is challenging due to numerous uncertainties and unknowns, especially relating to understanding system dynamics. Adaptive resource management (ARM) is a formal process to making logical and transparent recurrent decisions when there are uncertainties about system dynamics. Despite wide recognition and calls for implementing adaptive natural resource management, applications remain limited. More common is a reactive approach to decision making, which ignores future system dynamics. This contrasts with ARM, which anticipates future dynamics of ecological process and management actions using a model‐based framework. Practitioners may be reluctant to adopt ARM because of the dearth of comparative evaluations between ARM and more common approaches to making decisions. We compared the probability of meeting management objectives when managing a population under both types of decision frameworks, specifically in relation to typical uncertainties and unknowns. We use a population of Sandhill Cranes as our case study. We evaluate each decision process under varying levels of monitoring and ecological uncertainty, where the true underlying population dynamics followed a stochastic age‐structured population model with environmentally driven vital rate density dependence. We found that the ARM framework outperformed the currently employed reactive decision framework to manage Sandhill Cranes in meeting the population objective across an array of scenarios. This was even the case when the candidate set of population models contained only naïve representations of the true population process. Under the reactive decision framework, we found little improvement in meeting the population objective even if monitoring uncertainty was eliminated. In contrast, if the population was monitored without error within the ARM framework, the population objective was always maintained, regardless of the population models considered. Contrary to expectation, we found that age‐specific optimal harvest decisions are not always necessary to meet a population objective when population dynamics are age structured. Population managers can decrease risks and gain transparency and flexibility in management by adopting an ARM framework. If population monitoring data has high sampling variation and/or limited empirical knowledge is available for constructing mechanistic population models, ARM model sets should consider a range of mechanistic, descriptive, and predictive model types.
Secondary invasion un‐undefined: The importance of consistent and clear terminology for classifying unique invasion phenomena
Authors: O'Loughlin Luke S. , Green Peter T.
Published: April 2018

Linked Article: https://doi.org/10.1002/ece3.3966
Secondary invasion re‐redefined: The distinction between invader‐facilitated and invader‐contingent invasions as subclasses of secondary invasion
Authors: Pearson Dean E. , Ortega Yvette K. , Runyon Justin , Butler Jack L.
Published: April 2018

Linked Article: https://doi.org/10.1002/ece3.3964
Structure is more important than physiology for estimating intracanopy distributions of leaf temperatures
Authors: Woods H. Arthur , Saudreau Marc , Pincebourde Sylvain
Published: April 2018

Estimating leaf temperature distributions (LTDs) in canopies is crucial in forest ecology. Leaf temperature affects the exchange of heat, water, and gases, and it alters the performance of leaf‐dwelling species such as arthropods, including pests and invaders. LTDs provide spatial variation that may allow arthropods to thermoregulate in the face of long‐term changes in mean temperature or incidence of extreme temperatures. Yet, recording LTDs for entire canopies remains challenging. Here, we use an energy‐exchange model (RATP) to examine the relative roles of climatic, structural, and physiological factors in influencing three‐dimensional LTDs in tree canopies. A Morris sensitivity analysis of 13 parameters showed, not surprisingly, that climatic factors had the greatest overall effect on LTDs. In addition, however, structural parameters had greater effects on LTDs than did leaf physiological parameters. Our results suggest that it is possible to infer forest canopy LTDs from the LTDs measured or simulated just at the surface of the canopy cover over a reasonable range of parameter values. This conclusion suggests that remote sensing data can be used to estimate 3D patterns of temperature variation from 2D images of vegetation surface temperatures. Synthesis and applications. Estimating the effects of LTDs on natural plant–insect communities will require extending canopy models beyond their current focus on individual species or crops. These models, however, contain many parameters, and applying the models to new species or to mixed natural canopies depends on identifying the parameters that matter most. Our results suggest that canopy structural parameters are more important determinants of LTDs than are the physiological parameters that tend to receive the most empirical attention.