bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of High‐Energy Ball Milling on Mechanical Properties of the Mg–Nb Composites Fabricated through Powder Metallurgy Process
Authors: Vahid Alireza , Hodgson Peter , Li Yuncang
Published: November 2017

New biocompatible and biodegradable Mg–Nb composites used as bone implant materials are fabricated through powder metallurgy process. Mg–Nb mixture powders are prepared through mechanical milling and manual mixing. Then, the Mg–Nb composites are fabricated through cold press and sintering processes. The effect of mechanical milling and Nb particles as reinforcements on the microstructures and mechanical properties of Mg–Nb composites are investigated. The mechanical milling process is found to be effective in reducing the size of Mg and Nb particles, distributing the Nb particles uniformly in the Mg matrix and obtaining Mg–Nb composite particles. The Mg–Nb composite particles can be bound together firmly during the sintering process, result in Mg–Nb composite structures with no intermetallic formation, lower porosity, and higher mechanical properties compared to composites prepared through manual mixing. Interestingly, the mechanical properties of manually mixed Mg–Nb composites appear to be even lower than that of pure Mg.
A Multiparameter pH‐Sensitive Nanodevice Based on Plasmonic Nanopores
Authors: Liu Hailing , Jiang Qiucen , Pang Jie , Jiang Zeyu , Cao Jiao , Ji Lina , Xia Xinghua , Wang Kang
Published: November 2017

With controllable mass transfer and special optical properties, plasmonic nanopores may be applied as a nanodevice and possibly create a new generation of single molecule detection technique based on plasmon‐enhanced spectra. In the present study, gold nanoparticles self‐assemble into a gold porous sphere (GPS) on the tip of a glass nanopipette with the help of i‐motif DNA thiolated by both ends as linker molecules. The gaps among neighboring gold nanoparticles are considered as plasmonic nanopores. The size of the formed nanopores can be tuned by the folded–unfolded conformational change of i‐motif DNA upon pH adjustment from 4.5 to 7.0. Based on its tunable structural property, the GPS shows reversible changes in ionic current, potential, and surface‐enhanced Raman scattering signal. The GPS is further used to probe regional pH in single cells. The successful application of GPS in multiparameter pH probing and single cell analysis suggests that the new physical properties of the self‐assembled plasmonic nanopores can be used for fabricating multiple types of nanodevices and nanosensors.
Microenvironmental Stiffness of 3D Polymeric Structures to Study Invasive Rates of Cancer Cells
Authors: Lemma Enrico Domenico , Spagnolo Barbara , Rizzi Francesco , Corvaglia Stefania , Pisanello Marco , De Vittorio Massimo , Pisanello Ferruccio
Published: November 2017

Cells are highly dynamic elements, continuously interacting with the extracellular environment. Mechanical forces sensed and applied by cells are responsible for cellular adhesion, motility, and deformation, and are heavily involved in determining cancer spreading and metastasis formation. Cell/extracellular matrix interactions are commonly analyzed with the use of hydrogels and 3D microfabricated scaffolds. However, currently available techniques have a limited control over the stiffness of microscaffolds and do not allow for separating environmental properties from biological processes in driving cell mechanical behavior, including nuclear deformability and cell invasiveness. Herein, a new approach is presented to study tumor cell invasiveness by exploiting an innovative class of polymeric scaffolds based on two‐photon lithography to control the stiffness of deterministic microenvironments in 3D. This is obtained by fine‐tuning of the laser power during the lithography, thus locally modifying both structural and mechanical properties in the same fabrication process. Cage‐like structures and cylindric stent‐like microscaffolds are fabricated with different Young's modulus and stiffness gradients, allowing obtaining new insights on the mechanical interplay between tumor cells and the surrounding environments. In particular, cell invasion is mostly driven by softer architectures, and the introduction of 3D stiffness “weak spots” is shown to boost the rate at which cancer cells invade the scaffolds. The possibility to modulate structural compliance also allowed estimating the force distribution exerted by a single cell on the scaffold, revealing that both pushing and pulling forces are involved in the cell–structure interaction. Overall, exploiting this method to obtain a wide range of 3D architectures with locally engineered stiffness can pave the way for unique applications to study tumor cell dynamics.
Anion‐Regulated Selective Generation of Cobalt Sites in Carbon: Toward Superior Bifunctional Electrocatalysis
Authors: Wan Gang , Yang Ce , Zhao Wanpeng , Li Qianru , Wang Ning , Li Tao , Zhou Hua , Chen Hangrong , Shi Jianlin
Published: November 2017

The introduction of active transition metal sites (TMSs) in carbon enables the synthesis of noble‐metal‐free electrocatalysts for clean energy conversion applications; however, there are often multiple existing forms of TMSs, which are of different natures and catalytic models. Regulating the evolution of distinctive TMSs is highly desirable but remains challenging to date. Anions, as essential elements involved in the synthesis, have been totally neglected previously in the construction of TMSs. Herein, the effects of anions on the creation of different types of TMSs are investigated for the first time. It is found that the active cobalt–nitrogen sites tend to be selectively constructed on the surface of N‐doped carbon by using chloride, while metallic cobalt nanoparticles encased in protective graphite layers are the dominant forms of cobalt species with nitrate ions. The obtained catalysts demonstrate cobalt‐sites‐dependent activity for oxygen reduction reaction and hydrogen evolution reaction in acidic media. The remarkably enhanced catalytic activities approaching that of benchmark Pt/C in an acidic medium have been obtained on the catalyst dominated with cobalt–nitrogen sites, confirmed by the advanced spectroscopic characterization. This finding demonstrates a general paradigm of anion‐regulated evolution of distinctive TMSs, providing a new pathway for enhancing performances of various targeted reactions related with TMSs.
A Thermophilic Tetramolecular G‐Quadruplex/Hemin DNAzyme
Authors: Guo Yuehua , Chen Jielin , Cheng Mingpan , Monchaud David , Zhou Jun , Ju Huangxian
Published: November 2017

The quadruplex‐based DNAzyme system is one of the most useful artificial enzymes or catalysts; their unique properties make them reliable alternatives to proteins for performing catalytic transformation. The first prototype of a thermally stable DNAzyme system is presented. This thermophilic DNAzyme is capable of oxidizing substrates at high temperatures (up to 95 °C) and long reaction times (up to 18 h at 75 °C). The catalytic activity of the DNAzymes were investigated with the standard peroxidase‐mimicking oxidation of 2,2′‐azino‐bis(3‐ethylbenzothiozoline‐6‐sulfonic acid) (ABTS) by H2O2. The step‐by‐step design of this unique heat‐activated G‐quadruplex/hemin catalyst, including the modification of adenines at both ends of G‐tracts, the choice of cation, and its concentration for DNAzyme stabilization, is described. This work investigates thoroughly the molecular basis of these catalytic properties and provides an example of an industrially relevant application.
Ligand‐controlled Regiodivergent C−H Alkenylation of Pyrazoles and its Application to the Synthesis of Indazoles
Authors: Kim Hyun Tae , Ha Hyeri , Kang Geunhee , Kim Og Soon , Ryu Ho , Biswas Abul Kalam , Lim Sang Min , Baik Mu‐Hyun , Joo Jung Min
Published: November 2017

Regioselective C4‐, C5‐, and di‐alkenylations of pyrazoles were achieved. An electrophilic Pd catalyst generated by trifluoroacetic acid (TFA) and 4,5‐diazafluoren‐9‐one (DAF) leads to C4‐alkenylation, whereas KOAc and mono‐protected amino acid (MPAA) ligand Ac‐Val‐OH give C5‐alkenylation. A combination of palladium acetate, silver carbonate, and pivalic acid affords dialkenylation products. Annulation through sequential alkenylation, thermal 6π‐electrocyclization, and oxidation gives functionalized indazoles. This comprehensive strategy greatly expands the range of readily accessible pyrazole and indazole derivatives, enabling useful regiodivergent C−H functionalization of pyrazoles and other heteroaromatic systems.
A High‐Resolution Crystal Structure that Reveals Molecular Details of Target Recognition by the Calcium‐Dependent Lipopeptide Antibiotic Laspartomycin C
Authors: Kleijn Laurens H. J. , Vlieg Hedwich C. , Wood Thomas M. , Sastre Toraño Javier , Janssen Bert J. C. , Martin Nathaniel I.
Published: November 2017

The calcium‐dependent antibiotics (CDAs) are an important emerging class of antibiotics. The crystal structure of the CDA laspartomycin C in complex with calcium and the ligand geranyl‐phosphate at a resolution of 1.28 Å is reported. This is the first crystal structure of a CDA bound to its bacterial target. The structure is also the first to be reported for an antibiotic that binds the essential bacterial phospholipid undecaprenyl phosphate (C55‐P). These structural insights are of great value in the design of antibiotics capable of exploiting this unique bacterial target.
L3C3P3: Tricarbontriphosphide Tricyclic Radicals and Cations Stabilized by Cyclic (alkyl)(amino)carbenes
Authors: Li Zhongshu , Hou Yuanfeng , Li Yaqi , Hinz Alexander , Harmer Jeffrey R. , Su Cheng‐Yong , Bertrand Guy , Grützmacher Hansjörg
Published: November 2017

Alkynes usually oligomerize to give rings with a conjugated π‐electron system. In contrast, phosphaalkynes, R−C≡P, frequently give compounds with polycyclic structures, which are thermodynamically more stable than the corresponding π‐conjugated isomers. The syntheses of the first C3P3 tricyclic compounds are reported with either radical or cationic ground states stabilized by cyclic (alkyl)(amino)carbenes (CAACs). These compounds may be considered as examples of tricarbontriphosphide coordinated by carbenes and are likely formed via trimerization of the corresponding mono‐radicals CAAC‐CP.. The mechanism for the formation of these tricarbontriphosphide radicals has been rationalized by a combination of experiments and DFT calculations.
Solid‐State Structure of Protonated Ketones and Aldehydes
Authors: Stuart Daniel , Wetmore Stacey D. , Gerken Michael
Published: November 2017

Protonated carbonyl compounds have been invoked as intermediates in many acid‐catalyzed organic reactions. To gain key structural and electronic data about such intermediates, oxonium salts derived from five representative examples of ketones and aldehydes are synthesized in the solid state, and characterized by X‐ray crystallography and Raman spectroscopy for the first time. DFT calculations were carried out on the cations in the gas phase. Whereas an equimolar reaction of the carbonyl compounds, acetone, cyclopentanone, adamantanone, and acetaldehyde, with SbF5 in anhydrous HF yielded mononuclear oxonium cations, the same stoichiometry in a reaction with benzaldehyde resulted in formation of a hemiprotonated, hydrogen‐bridged dimeric cation. Hemiprotonated acetaldehyde was obtained when a 2:1 ratio of aldehyde and SbF5 was used. Experimental and NBO analyses quantify the significant increase in electrophilicity of the oxonium cations compared to that of the parent ketones/aldehydes.
1,1‐Hydroboration and a Borane Adduct of Diphenyldiazomethane: A Potential Prelude to FLP‐N2 Chemistry
Authors: Tang Connie , Liang Quiming , Jupp Andrew R. , Johnstone Timothy C. , Neu Rebecca C. , Song Datong , Grimme Stefan , Stephan Douglas W.
Published: November 2017

Diphenyldiazomethane reacts with HB(C6F5)2 and B(C6F5)3, resulting in 1,1‐hydroboration and adduct formation, respectively. The hydroboration proceeds via a concerted reaction involving initial formation of the Lewis adduct Ph2CN2BH(C6F5)2. The highly sensitive adduct Ph2CN2(B(C6F5)3) liberates N2 and generates Ph2CB(C6F5)3. DFT computations reveal that formation of Ph2CN2B(C6F5)3 from carbene, N2, and borane is thermodynamically favourable, suggesting steric frustration could preclude carbene–borane adduct formation and affect FLP‐N2 capture.
Radical Copolymerization of Vinyl Ethers and Cyclic Ketene Acetals as a Versatile Platform to Design Functional Polyesters
Authors: Tardy Antoine , Honoré Jean‐Claude , Tran Johanna , Siri Didier , Delplace Vianney , Bataille Isabelle , Letourneur Didier , Perrier Josette , Nicoletti Cendrine , Maresca Marc , Lefay Catherine , Gigmes Didier , Nicolas Julien , Guillaneuf Yohann
Published: November 2017

Free‐radical copolymerization of cyclic ketene acetals (CKAs) and vinyl ethers (VEs) was investigated as an efficient yet simple approach for the preparation of functional aliphatic polyesters. The copolymerization of CKA and VE was first predicted to be quasi‐ideal by DFT calculations. The theoretical prediction was experimentally confirmed by the copolymerization of 2‐methylene‐1,3‐dioxepane (MDO) and butyl vinyl ether (BVE), leading to rMDO=0.73 and rBVE=1.61. We then illustrated the versatility of this approach by preparing different functional polyesters: 1) copolymers functionalized by fluorescent probes; 2) amphiphilic copolymers grafted with poly(ethylene glycol) (PEG) side chains able to self‐assemble into PEGylated nanoparticles; 3) antibacterial films active against Gram‐positive and Gram‐negative bacteria (including a multiresistant strain); and 4) cross‐linked bioelastomers with suitable properties for tissue engineering applications.
Cyclic Triimidazole Derivatives: Intriguing Examples of Multiple Emissions and Ultralong Phosphorescence at Room Temperature
Authors: Lucenti Elena , Forni Alessandra , Botta Chiara , Carlucci Lucia , Giannini Clelia , Marinotto Daniele , Pavanello Alessandro , Previtali Andrea , Righetto Stefania , Cariati Elena
Published: November 2017

The performance of solid luminogens depends on both their inherent electronic properties and their packing status. Intermolecular interactions have been exploited to achieve persistent room‐temperature phosphorescence (RTP) from organic molecules. However, the design of organic materials with bright RTP and the rationalization of the role of interchromophoric electronic coupling remain challenging tasks. Cyclic triimidazole has been shown to be a promising scaffold for such purposes owing to its crystallization‐induced room‐temperature ultralong phosphorescence (RTUP), which has been associated with H‐aggregation. Herein, we report three triimidazole derivatives as significant examples of multifaceted emission. In particular, dual fluorescence, RTUP, and phosphorescence from the molecular and supramolecular units were observed. H‐aggregation is responsible for the red RTUP, and Br substituents favor yellow molecular phosphorescence while halogen‐bonded Br⋅⋅⋅Br tetrameric units are involved in the blue‐green phosphorescence.
Organocatalytic Atroposelective Arylation of 2‐Naphthylamines as a Practical Approach to Axially Chiral Biaryl Amino Alcohols
Authors: Chen Ye‐Hui , Qi Liang‐Wen , Fang Fang , Tan Bin
Published: November 2017

The first phosphoric acid catalyzed direct arylation of 2‐naphthylamines with iminoquinones for the atroposelective synthesis of axially chiral biaryl amino alcohols has been developed. This reaction constitutes a highly functional‐group‐tolerant route for the rapid construction of enantioenriched axially chiral biaryl amino alcohols, and is a rare example of 2‐naphthylamines acting as nucleophiles in an organocatalytic enantioselective transformation. Furthermore, the products, which feature various halogen atoms, provide access to structurally diverse axially chiral amino alcohols through further transformations.
A synthesis study of phosphonated PSEBS for high temperature proton exchange membrane fuel cells
Authors: Elumalai Vijayakumar , Annapooranan Raja , Ganapathikrishnan Madhubala , Sangeetha Dharmalingam
Published: November 2017

A series of novel phosphonated proton exchange membranes has been prepared using poly(styrene‐ethylene/butylene‐styrene) block copolymer (PSEBS) as base material. Phosphonic acid functionalization of the polymer was performed by a simple two‐step process, via chloromethylation of PSEBS followed by phosphonation utilizing the Michaels–Arbuzov reaction. The successful phosphonation of the polymers were characterized by NMR and Fourier transform infrared. The phosphonated ester form of the membranes were obtained by solvent evaporation method and hydrolyzed to get a proton conducting membrane. The membrane properties such as ion exchange capacity, water uptake and proton conductivity at various temperatures were examined for their suitability to be utilized as a high temperature polymer electrolyte. Additionally, the morphology, thermal, and mechanical properties of the synthesized membranes were investigated, using scanning electron microscope, thermogravimetric analysis, and tensile test, respectively. The effective (anhydrous) proton conductivity was studied with respect to various degrees of functionalization. From the studies, the membranes were found to have a comparatively good conductivity and one of the membranes reached the maximum value of 5.81 mS/cm2 at 140 °C as measured by impedance analyzer. It was found that the synthesized membranes were mechanically durable, chemically, and thermally stable. Hence, the synthesized phosphonated membranes could be a promising candidate for high temperature polymer electrolyte fuel cell applications. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45954.
Early Gestational Hypoxia and Adverse Developmental Outcomes
Authors: Ritchie Helen E. , Oakes Diana J. , Kennedy Debra , Polson Jaimie W.
Published: November 2017

Hypoxia is a normal and essential part of embryonic development. However, this state may leave the embryo vulnerable to damage when oxygen supply is disturbed. Embryofetal response to hypoxia is dependent on duration and depth of hypoxia, as well as developmental stage. Early postimplantation rat embryos were resilient to hypoxia, with many surviving up to 1.5 hr of uterine clamping, while most mid‐gestation embryos were dead after 1 hour of clamping. Survivors were small and many had a range of defects, principally terminal transverse limb reduction defects. Similar patterns of malformations occurred when embryonic hypoxia was induced by maternal hypoxia, interruption of uteroplacental flow, or perfusion and embryonic bradycardia. There is good evidence that high altitude pregnancies are associated with smaller babies and increased risk of some malformations, but these results are complicated by increased risk of pre‐eclampsia. Early onset pre‐eclampsia itself is associated with small for dates and increased risk of atrio‐ventricular septal defects. Limb defects have clearly been associated with chorionic villus sampling, cocaine, and misoprostol use. Similar defects are also observed with increased frequency among fetuses who are homozygous for thalassemia. Drugs that block the potassium current, whether as the prime site of action or as a side effect, are highly teratogenic in experimental animals. They induce embryonic bradycardia, hypoxia, hemorrhage, and blisters, leading to transverse limb defects as well as craniofacial and cardiovascular defects. While evidence linking these drugs to birth defects in humans is not compelling, the reason may methodological rather than biological. Birth Defects Research 109:1358–1376, 2017.© 2017 Wiley Periodicals, Inc.
Regional differences in right versus left congenital heart disease diagnoses in neonates in the United States
Authors: Nelson Jennifer S. , Strassle Paula D.
Published: November 2017

Background

Differences in the prevalence of left and right congenital heart defects (CHD) across the United States are unclear. This study evaluated the overall prevalence and the distribution of right versus left CHD across US regions and divisions in neonates.

Methods

Newborns born from 2000 to 2014 diagnosed with CHD were identified using the National Inpatient Sample. Heart defects were stratified into right, left, and “neither” subtypes. The risk of right and left heart diagnoses between US Census regions and divisions was compared using multivariable binomial regression, adjusting for infant, and hospital characteristics.

Results

Two hundred forty thousand four hundred fifty‐five newborns were included and 38,185 (15.9%) were classifiable as having either right or left subtypes. Between 2000 and 2014, the prevalence of right defects increased from 1.65 to 2.88 cases/1,000 live born infants (p < .0001), left defects increased from 0.47 to 0.75 cases/1,000 live born infants (p < .0001), and “neither” defects increased from 10.82 to 20.09 cases/1,000 live born infants (p < .0001). Newborns in the Northeast (RDadj .03, 95% CI .02, .03), Midwest (RDadj .02, 95% CI .02, .03), and South (RDadj .02, 95% CI .02, .02) were significantly more likely to have a right heart defect diagnosis compared to the West. When stratified by division, New England states had a significantly higher prevalence of right defects compared to the Pacific (RDadj .09, 95% CI .06, 0.11). No differences in the prevalence of left defects were seen.

Conclusions

The prevalence of CHD diagnoses at birth in the US has increased, and regional differences in the prevalence of right defects appear to exist.
Hypoxia: From Placental Development to Fetal Programming
Authors: Fajersztajn Lais , Veras Mariana Matera
Published: November 2017

Hypoxia may influence normal and different pathological processes. Low oxygenation activates a variety of responses, many of them regulated by hypoxia‐inducible factor 1 complex, which is mostly involved in cellular control of O2 consumption and delivery, inhibition of growth and development, and promotion of anaerobic metabolism. Hypoxia plays a significant physiological role in fetal development; it is involved in different embryonic processes, for example, placentation, angiogenesis, and hematopoiesis. More recently, fetal hypoxia has been associated directly or indirectly with fetal programming of heart, brain, and kidney function and metabolism in adulthood. In this review, the role of hypoxia in fetal development, placentation, and fetal programming is summarized. Hypoxia is a basic mechanism involved in different pregnancy disorders and fetal health developmental complications. Although there are scientific data showing that hypoxia mediates changes in the growth trajectory of the fetus, modulates gene expression by epigenetic mechanisms, and determines the health status later in adulthood, more mechanistic studies are needed. Furthermore, if we consider that intrauterine hypoxia is not a rare event, and can be a consequence of unavoidable exposures to air pollution, nutritional deficiencies, obesity, and other very common conditions (drug addiction and stress), the health of future generations may be damaged and the incidence of some diseases will markedly increase as a consequence of disturbed fetal programming. Birth Defects Research 109:1377–1385, 2017.© 2017 Wiley Periodicals, Inc.
Improvements in problem behavior in a child with autism spectrum diagnosis through synthesized analysis and treatment: A replication in an EIBI home program
Authors: Strand Rebekka C.W. , Eldevik Sigmund
Published: November 2017

A recent study described a synthesized treatment where a functional analysis was based on an open‐ended interview and combined with functional communication and delay‐tolerance training. The treatment resulted in a reduction in problem behaviors and an increase in appropriate requests. Most of the analysis and intervention were done in a clinic setting, and required weekly visits by the family. This present study is a systematic replication, where we conducted the same synthesized treatments, with a young child with Autism Spectrum Disorder (ASD) enrolled in a home‐based Early Intensive Behavior Intervention program, EIBI. Outcomes were similar with a marked reduction in problem behaviors and an increase in appropriate requests. These findings suggest that it is possible to conduct this intervention in a home setting, with weekly consultations with parents. Our study show the utility of the synthesized treatment in an EIBI program in a home setting and how this can contribute to client time and costs.
Using computer‐assisted instruction to increase the eye gaze of children with autism
Authors: Miller Neal , Wyatt Jennifer , Casey Laura Baylot , Smith J. Brian
Published: November 2017

Many children diagnosed with autism spectrum disorders have difficulty making appropriate eye contact and engaging in joint attention. The current study evaluated a computer‐assisted instruction package (pairing visual stimuli with vocal stimuli) as a novel treatment to improve the eye gaze accuracy in 3 elementary school children with autism. The researchers measured the latency from a recorded verbal stimulus to the students making eye contact with pictures of familiar individuals displayed on a computer screen, and the duration for which eye gaze on the stimulus was maintained. An automated infrared camera system for measuring eye gaze was utilized that eliminated the need for an instructor to make subjective judgments regarding participants' eye gaze. For all three participants, duration of eye contact increased, and latency to responding decreased following exposure to the computer‐assisted instruction. The implications of these findings for the treatment of individuals with autism are discussed, along with suggestions for future research on the topic.
Enhanced tissue adhesiveness of injectable gelatin hydrogels through dual catalytic activity of horseradish peroxidase
Authors: Hoang Thi Thai Thanh , Lee Yunki , Ryu Seung Bae , Nguyen Dai Hai , Park Ki Dong
Published: November 2017

Development of bioadhesives with tunable mechanical strength, high adhesiveness, biocompatibility, and injectability is greatly desirable in all surgeries to replace or complement the sutures and staples. Herein, the dual catalytic activity of horseradish peroxidase is exploited to in situ form the hydroxyphenyl propionic acid‐gelatin/thiolated gelatin (GH/GS) adhesive hydrogels including two alternative crosslinks (phenol‐phenol and disulfide bonds) with fast gelation (few seconds – several minutes) and improved physicochemical properties. Their elastic moduli increase from 6.7 to 10.3 kPa by adding GS polymer that leads to the better stability of GH/GS hydrogels than GH ones. GH/GS adhesive strength is respectively 6.5‐fold and 15.8‐fold higher than GH‐only and fibrin glue that is due to additional disulfide linkages between hydrogels and tissues. Moreover, in vitro cell study with human dermal fibroblast showed the cell‐compatibility of GH/GS hydrogels. Taken together, GH/GS hydrogels can be considered as promising potential adhesive materials for various biomedical applications.
Lego bricks and the octet rule: Molecular models for biochemical pathways with plastic, interlocking toy bricks
Authors: Lin Henry J. , Lehoang Jennifer , Kwan Isabel , Baghaee Anita , Prasad Priya , Ha‐Chen Stephanie J. , Moss Tanesha , Woods Jeremy D.
Published: November 2017

The 8 studs on a 2 × 4 Lego brick conveniently represent the outer shell of electrons for carbon, nitrogen, and oxygen atoms. We used Lego bricks to model these atoms, which are then joined together to form molecules by following the Lewis octet rule. A variety of small biological molecules can be modeled in this way, such as most amino acids, fatty acids, glucose, and various intermediate metabolites. Model building with these familiar toys can be a helpful, hands‐on exercise for learning—or re‐learning—biochemical pathways. © 2017 by The International Union of Biochemistry and Molecular Biology, 46(1):54–57, 2018.
Simultaneous determination and tissue distribution studies of four phenolic acids in rat tissue by UFLC–MS/MS after intravenous administration of salvianolic acid for injection
Authors: Li Shuang , Xie Xiuman , Li Dongxiang , Yu Zhiguo , Tong Ling , Zhao Yunli
Published: November 2017

A rapid, simple and sensitive ultra‐fast liquid chromatography tandem mass spectrometric method was developed and validated for simultaneous determination and tissue distribution studies of rosmarinic acid, salvianolic acid D, lithospermic acid and salvianolic acid B in rats after intravenous administration of salvianolic acid for injection. The tissue homogenate samples were pretreated by protein precipitation with pre‐cooled acetonitrile. Chromatographic separation was achieved on a Waters Cortecs UPLC C18 column (1.6 μm, 2.1 × 100 mm) with a mobile phase composed of 0.1% formic acid–water and 0.1% formic acid–acetonitrile. Analytes were detected by electrospray ionization mass spectrometry and quantitated using multiple reaction monitoring. The method was fully validated. The calibration curves for the four phenolic acids were linear in the given concentration ranges. The precisions (relative standard deviation) in the measurement of quality control samples were <10% and the accuracies (relative error) were in the range of 0.28–11.22%. The reliable method was successfully applied to the tissue distribution studies of the four phenolic acids. The results showed that rosmarinic acid, salvianolic acid D, lithospermic acid and salvianolic acid B were rapidly distributed in tissues with the major amount found in kidney, and little crossed the blood–brain barrier. The developed method and the results provide a basis for further studies.
SEED: A software tool and an active‐learning strategy for data structures courses
Authors: Adarme Marco , Jabba Molinares Daladier
Published: November 2017

SEED is a software tool designed for Java consisting of a class library and a set of simulators to facilitate learning of the main data structures. The educational component is based on an active case‐solving methodology accompanied by a pedagogical strategy. This strategy allows for the development of a multilayer‐model‐programming work for the construction of basic and advanced applications in real domains and for integration of its use, development and operation assessment with data structures. The evaluation results of SEED as a pedagogical mediator in the issue of binary trees is presented. The evaluation indicates that students prefer to use SEED due to its simplicity and attractive GUIs which facilitate data structures learning.
If you prick us, do we not bleed?
Authors: Ahmed Ameera , Henry Timothy D.
Published: November 2017

Key Points

Women have higher post PCI bleeding complications which in turn contributes to higher post PCI mortality.

Bivalirudin decreases bleeding events in both men and women when compared to use of both heparin and GPI but bleeding avoidance strategies such as radial artery access or avoiding GPI may modify that benefit.

The NCDR bleeding risk score incorporates gender and is predictive of both bleeding complications and mortality. The ideal strategy to reduce bleeding will depend on the specific patient, local practice patterns, and ideally cost effectiveness.
Coronary resting gradients for hemodynamic lesion assessment ‐ The future of coronary physiology?
Authors: Shlofmitz Evan , Jeremias Allen
Published: November 2017

Key Points

Coronary resting gradient measurements with cut‐off values of ≤0.87 and ≥0.93 portend a high degree of certainty with respect to appropriateness of coronary revascularization

Less agreement exists in patients in the so called indeterminate “gray zone”

Pressure‐bounded coronary flow reserve may aid in our understanding of the underlying physiologic principles and facilitate the clinical assessment of these lesions
PVL closure after TAVR: Yes, we can do it
Authors: Cilingiroglu Mehmet , Paixao Andre
Published: November 2017

Key Points

Paravalvular leak (PVL) remains a significant problem after transcatheter aortic valve replacement.

PVL is associated with long‐term morbidity and mortality.

Percutaneous management of post‐TAVR PVL seems to be feasible and should be adopted by the structural heart interventionalist.
Vapor‐Phase Hydrodeoxygenation of Guaiacol to Aromatics over Pt/HBeta: Identification of the Role of Acid Sites and Metal Sites on the Reaction Pathway
Authors: Nie Lei , Peng Bo , Zhu Xinli
Published: November 2017

A comparative study of the hydrodeoxygenation of guaiacol, a phenolic compound derived from the lignin fraction of biomass with both hydroxyl and methoxyl functional groups, was performed on HBeta, Pt/SiO2, and Pt/HBeta at 350 °C and atmospheric pressure. The reaction pathway and the roles of the acid and metal sites were studied. Acid sites catalyze transalkylation and dehydroxylation reactions to produce monohydroxyl phenolics (phenol, cresols, and xylenols) as the major final products. Pt sites catalyze demethylation to result in catechol as the primary product, which can either be deoxygenated to phenol followed by phenol to benzene, or decarbonylated to cyclopentanone and further to butane. The close proximity of Pt and acid sites in bifunctional Pt/HBeta improves transalkylation and deoxygenation (or dehydroxylation) reactions and inhibits demethylation and decarbonylation reactions significantly, which leads to aromatics as the major final products with a total yield >85 %. Both the activity and stability of bifunctional Pt/HBeta during the hydrodeoxygenation of guaiacol are improved compared to those of HBeta and Pt/SiO2. The addition of water to the feed further improves the activity and stability through the hydrolysis of the O−CH3 bond of guaiacol on acid sites and the removal of coke around Pt.
Auto‐Tandem Catalysis: PdII‐Catalysed Dehydrogenation/Oxidative Heck Reaction of Cyclopentane‐1,3‐diones
Authors: Lamb Claire J. C. , Nderitu Bryan G. , McMurdo Gemma , Tobin John M. , Vilela Filipe , Lee Ai‐Lan
Published: November 2017

A PdII catalyst system has been used to successfully catalyse two mechanistically distinct reactions in a one‐pot procedure: dehydrogenation of 2,2‐disubstituted cyclopentane‐1,3‐diones and the subsequent oxidative Heck coupling. This auto‐tandem catalytic reaction is applicable to both batch and continuous flow processes, with the latter being the first example of a tandem aerobic dehydrogenation/oxidative Heck in flow. In addition, a telescoped reaction involving enantioselective desymmetrisation of the all‐C quaternary centre was successfully achieved.
Catalytic Asymmetric Synthesis of Fluoroalkyl‐Containing Compounds by Three‐Component Photoredox Chemistry
Authors: Ma Jiajia , Xie Xiulan , Meggers Eric
Published: November 2017

Multicomponent reactions allow the construction of molecular complexity in an economical fashion, fluorinated compounds play an important role in pharmaceuticals and agrochemicals, whereas visible light is an abundant and sustainable source of energy for activating chemical transformations. Here we report a visible‐light‐induced asymmetric three‐component fluoroalkylation reaction scheme catalyzed by a chiral‐at‐rhodium Lewis acid. The photoredox process is mediated by the inexpensive, commercially available organic photoredox mediator 4,4′‐difluorobenzil, which upon activation by visible light induces the generation of perfluoroalkyl radicals from their sulfinates via single electron transfer oxidation. The fluorinated radicals are trapped by electron‐rich C−C double bonds to deliver α‐oxy carbon‐centered radicals, followed by a subsequent stereocontrolled reaction with acceptor‐substituted alkenes. This three‐component fluoroalkylation scheme provides a range of complex fluoroalkyl‐containing chiral compounds under dual C−C bond formation with high enantioselectivities (up to 98 % ee) and modest diastereoselectivities (up to 6:1 dr). Excellent diastereoselectivities (up to >38:1:1 dr) for natural chiral compound derivatives are observed. Broad substrate scope (25 examples), excellent functional group tolerance, scalability of the reaction, along with the option to recover the chiral catalyst and photoredox mediator reveal the practicability of this methodology in organic synthesis for the rapid synthesis of fluorinated chiral molecules.
Dendritic and Core–Shell–Corona Mesoporous Sister Nanospheres from Polymer–Surfactant–Silica Self‐Entanglement
Authors: Zhang Kun , Yang Tai‐Qun , Shan Bing‐Qian , Liu Peng‐Cheng , Peng Bo , Xue Qing‐Song , Yuan En‐Hui , Wu Peng , Albela Belén , Bonneviot Laurent
Published: November 2017

Mesoporous nanospheres are highly regarded for their applications in nanomedicine, optical devices, batteries, nanofiltration, and heterogeneous catalysis. In the last field, the dendritic morphology, which favors molecular diffusion, is a very important morphology known for silica, but not yet for carbon. A one‐pot, easy, and scalable co‐sol–gel route by using the triphasic resol–surfactant–silica system is shown to yield the topologies of dendritic and core–shell–corona mesoporous sister nanospheres by inner radial phase speciation control on a mass‐transfer‐limited process, depending on the relative polycondensation rates of the resol polymer and silica phases. The trick was the use of polyolamines with different catalytic activities on each hard phase polycondensation. The self‐entanglement of phases is produced at the {O−, S+, I−} organic–surfactant–inorganic interface. Mono‐ and biphasic mesoporous sister nanospheres of carbon and/or silica are derivatized from each mother nanospheres and called “syntaxic” because of similar sizes and mirrored morphologies. Comparing these “false twins”, or yin and yang mesoporous nanospheres, functionalized by sulfonic groups provides evidence of the superiority of the dendritic topologies and the absence of a shell on the diffusion‐controlled catalytic alkylation of m‐cresol.
Co‐Cluster‐Based Metal–Organic Frameworks as Selective Catalysts for Benzene Tandem Acylation–Nazarov Cyclization to Benzocyclopentanone
Authors: Liu Mengjia , Gao Kuan , Fan Yanru , Guo Xiaoqing , Wu Jie , Meng Xiangru , Hou Hongwei
Published: November 2017

One‐step selective benzene acylation–Nazarov cyclization is an attractive, yet challenging method for the synthesis of the benzocyclopentanone skeleton, which is key intermediate of many natural products. Herein, two metal‐cluster‐based metal–organic frameworks (MCOFs) {(H3O)2[Co4(pbcd)2(μ3‐OH)2]⋅CH3CH2OH⋅4 H2O}n (1; pbcd=9,9′‐(propan‐1,3‐diyl)bis(9H‐carbazole‐3,6‐dicarboxylic acid) and {[Co5.25(mcd)2(HCO2)(μ2‐O)0.5(μ3‐OH)0.5(H2O)4]⋅6 H2O⋅5 DMF}n (2; mcd=9,9′‐methylenebis(9H‐carbazole‐3,6‐dicarboxylic acid) were developed to catalyze a tandem Nazarov cyclization reaction of 1,3‐dimethoxybenzene with α,β‐unsaturated carboxylic acids for the synthesis of cyclopentenone[b]benzenes. MCOFs 1 and 2, which were constructed from tetranuclear CoII cluster [Co4(μ3‐OH)2] and hexanuclear CoII cluster [Co6(HCO2)(μ2‐O)(μ3‐OH)], respectively, exhibit high catalytic activity arising not only from their suitable channel size and accessible catalytic sites, but also because of their high density of Lewis acidic sites within the frameworks and the synergic activity among CoII ions. In contrast, {[Co2(pbcd)(bpe)]⋅2 H2O⋅2 DMF}n (3; bpe=1,2‐bis(pyridin‐4‐yl)ethane) containing binuclear CoII and having large pore windows is a highly selective catalyst for obtaining exclusively the acylation products. Easy product separation, simple reaction procedures, and catalyst recycling make the catalyst system attractive. This work highlights the synergistic effect among ions of MCOFs in interacting with substrates in a sequential or cooperative manner to achieve tandem catalysis.
Addressing the Nature of Phosphinidene Sulfides via the Synthesis of P−S Heterocycles
Authors: Graham Cameron M. E. , Macdonald Charles L. B. , Boyle Paul D. , Wisner James A. , Ragogna Paul J.
Published: November 2017

The phosphorus–sulfur heterocycles 1,2‐thiaphosphetenes and phosphirene sulfides have been prepared, and represent the first structurally characterized derivatives for either class of compound. These strained P−S ring systems are formed by the reaction of a phosphinidene sulfide and alkyne. Using an internal alkyne, only the 3‐membered PV, phosphirene sulfide was produced, whereas a terminal alkyne yielded a mixture of phosphirene sulfide and 1,2‐thiaphosphetene (PIII). Detailed computational analysis revealed that for numerous derivatives of alkynes, the corresponding 4‐membered rings are always more stable than the 3‐membered isomers. The electronic nature of “free” phosphinidene sulfides (R−P=S) is discussed based on computational results.
Particle Measurement Techniques in Fluid Process Engineering
Authors: Lichti Markus , Bart Hans‐Jörg
Published: November 2017

Partikuläre Systeme sind ubiquitär und kommen in der Fluidverfahrenstechnik in Form von Tropfen, Blasen oder Feststoffpartikeln vor. Nicht nur ihre Konzentration, sondern auch ihre Verteilung bestimmt oft maßgeblich den jeweiligen Prozess. In diesem Beitrag wird ein Überblick über gängige invasive und nichtinvasive Messverfahren zur Erfassung von Blasen und Tropfen vorgestellt. Die Vor‐ und Nachteile zur Erfassung von Phasen‐ und Partikelgrößenverteilungen in Mehrphasensystemen werden angesprochen und Funktionsprinzipien, deren Anwendbarkeit im Labor sowie Grenzen im industriellen Einsatz aufgezeigt und diskutiert.
Mass Transfer During Droplet Formation – A Measuring Technique Study
Authors: Heine Jens S. , Bart Hans‐Jörg
Published: November 2017

In liquid‐liquid extraction processes, the mass transfer coefficient is one of the key design parameters. In the present study, the impact on mass transfer during droplet formation in a quiescent continuous phase is investigated analytically. Therefore, confocal Raman spectroscopy in a novel measurement cell combined with interfacial tension measurements are applied. It could be shown, that Marangoni effects in the system toluene‐acetonitrile‐water (mass transfer direction from the dispersed to the continuous phase) lead to 50 % of mass transferred in the first 5 s when 90 % is transferred in 1 min.
A New Pentiptycene‐Based Dianhydride and Its High‐Free‐Volume Polymer for Carbon Dioxide Removal
Authors: Shamsabadi Ahmad Arabi , Seidi Farzad , Nozari Mohammad , Soroush Masoud
Published: November 2017

In addition to possessing excellent chemical, mechanical, and thermal stability, polyimides and polyetherimides have excellent solubility in many solvents, which renders them suitable for membrane preparation. Two new monomers [a pentiptycene‐based dianhydride (PPDAn) and a pentiptycene imide‐containing diamine (PPImDA)] and a pentiptycene‐based polyimide [PPImDA‐4,4′‐hexafluoroisopropylidene diphthalic anhydride (PPImDA‐6FDA)] have been synthesized and characterized by FTIR and 1H NMR spectroscopy, gel‐permeation chromatography, mass spectrometry, X‐ray photoelectron spectroscopy, thermogravimetric analysis, differential scanning calorimetry, BET surface area, and X‐ray diffraction. High‐molecular‐weight PPImDA‐6FDA has remarkable thermal stability and excellent solubility in common organic solvents. It also has an extraordinarily high fractional free volume (0.233) owing to the presence of −C(CF3)2− units, the rigid diamine, and the pentiptycene moiety in the polymer structure. It has high CO2 permeability (812 Barrer) owing to poor chain packing, which is caused by the fact that its rigid groups veil the influence of the ethereal oxygen groups in its backbone. It has the highest CO2 permeability among all reported pentiptycene‐containing polymers (about six times higher than that of the most permeable one) without sacrificing selectivity. The high free volume, good microporosity, high solubility in many solvents, and remarkable thermal stability of PPImDA‐6FDA point to the great potential of this polymer for CO2 removal.
Hierarchical Core–Shell Nickel Cobaltite Chestnut‐like Structures as Bifunctional Electrocatalyst for Rechargeable Metal–Air Batteries
Authors: Lee Dong Un , Park Moon Gyu , Cano Zachary Paul , Ahn Wook , Chen Zhongwei
Published: November 2017

Nano‐engineered hierarchical core–shell nickel cobaltite chestnut‐like structures were successfully synthesized as a bifunctionally active electrocatalyst for rechargeable metal–air battery applications. Both the morphology and composition of the catalyst were optimized by a facile hydrothermal reaction, resulting in a 10 h reacted sample demonstrating significantly enhanced activity toward both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in 0.1 m KOH. Specifically, the catalyst demonstrated −0.28 and 0.60 V versus SCE (saturated calomel electrode) at the ORR half‐wave potential and an OER current density of 10 mA cm−2, respectively. The resulting ORR/OER potential difference of 0.90 V was the smallest compared to the catalysts synthesized using 2, 6, and 12 h of hydrothermal reaction time. The excellent bifunctional activity of the catalyst is attributed to the nanoscale porous morphology and the spinel nickel cobaltite composition, which improved the active site exposure and transport of reactants and charges during the oxygen reactions.
An improved Apriori–based algorithm for friends recommendation in microblog
Authors: Liu Li , Yu Shuo , Wei Xiang , Ning Zhaolong
Published: November 2017

With the rapid development of Internet, the world has come into a new era of network interaction. Internet development in China makes various kinds of software available to users, by which relatives, close friends, and partners can achieve real‐time interactions. It is acknowledged that the recommended issues and persons are the most important parts for user experience. This study concentrates on how to provide a recommendation for users with a common interest in Microblog. We first illustrate some recommended algorithms based on data mining, and the implementation process of friend‐recommended system is then stated. After that, by integrating the characteristics of the user information, the forwarding and comments on information to associated users, we present an improved Apriori–based algorithm to rank the recommended information with confidence interval. Simulation results demonstrate the superiority and efficiency of our method.
The physical approximation of APP and BACE‐1: A key event in alzheimer's disease pathogenesis
Authors: Sun Jichao , Roy Subhojit
Published: November 2017

Alzheimer's disease (AD) is characterized by the accumulation of insoluble deposits of Amyloid β (Aβ) in brains. Aβ is derived by sequential cleavage of the amyloid precursor protein (APP) by β‐site secretase enzyme (BACE‐1) and γ‐secretase. Proteolytic processing of APP by BACE‐1 is the rate‐limiting step in Aβ production, and this pathway is a prime target for AD drug development. Both APP and BACE‐1 are membrane‐spanning proteins, transported via secretory and endocytic pathways; and the physical interaction of APP and BACE‐1 during trafficking is a key cell biological event initiating the amyloidogenic pathway. Here, we highlight recent research on intracellular trafficking/sorting of APP and BACE‐1, and discuss how dysregulation of these pathways might lead to enhanced convergence of APP and BACE‐1, and subsequent β‐cleavage of APP. © 2018 Wiley Periodicals, Inc. Develop Neurobiol 78: 340–347, 2018