bluuebunny/crossref_metadata_2025_split huggingface dataset:
Divergent Total Syntheses of Enmein‐Type Natural Products: (−)‐Enmein, (−)‐Isodocarpin, and (−)‐Sculponin R
Authors: Pan Saiyong , Chen Sicong , Dong Guangbin 
Published: April 2018

AbstractDivergent total syntheses of the enmein‐type natural products (−)‐enmein, (−)‐isodocarpin, and (−)‐sculponin R have been achieved in a concise fashion. Key features of the strategy include 1) an efficient early‐stage cage formation to control succeeding diastereoselectivity, 2) a one‐pot acylation/akylation/lactonization to construct the C‐ring and C8 quarternary center, 3) a reductive alkenylation approach to construct the enmain D/E rings and 4) a flexible route to allow divergent syntheses of three natural products.
Design, synthesis, and biological evaluation of 2‐substituted‐2,3,4,9‐tetrahydrospiro‐β‐carboline‐3‐carboxylic acid derivatives as first‐in‐class mast cell stabilizers
Authors: Singh Jatinder , Shah Ramanpreet , Singh Dhandeep , Jaggi Amteshwar S. , Singh Nirmal 
Published: April 2018

AbstractMast cell degranulation plays a momentous role in myriad diseases like asthma, eczema, allergic rhinitis, and conjunctivitis as well as anaphylactic shock; hence, there is an unmet need for developing new mast cells stabilizers. The reported mast cell stabilizers have a heterocyclic moiety and an acidic group. Furthermore, the role of tryptophan in suppression of mast cell activation is established. Hence, we prepared constrained analogs of tryptophan, which are derivatives of 2,3,4,9‐tetrahydrospiro‐β‐carboline‐3‐carboxylic acid, and evaluated them forex vivoinhibition of compound 48/80‐induced mast degranulation activity. By comparing IC50(μM) values with that of the standard drug sodium cromoglycate (IC50 = 0.489 ± 0.003 μM), compounds with bulky groups like heptyl (compound9; IC50 = 0.389 ± 0.015 μM) and octyl (compound10; IC50 = 0.354 ± 0.023 μM) were found to be of similar potency as sodium cromoglycate. Furthermore, the polar group‐containing compounds like the chloropropyl (compound16; IC50 = 0.382 ± 0.083 μM) and benzoyl derivative (compound14; IC50 = 00.469 ± 0.032 μM) were also found to be of similar potency as sodium cromoglycate. This is a seminal study of spiro‐β‐carboline mast cell stabilization having a wider scope in mast cell research; yet, the mechanism of action remains elusive.
Long‐Term Outcomes Following Achievement of Clinically Inactive Disease in Juvenile Idiopathic Arthritis
Authors: Shoop‐Worrall Stephanie J. W. , Verstappen Suzanne M. M. , McDonagh Janet E. , Baildam Eileen , Chieng Alice , Davidson Joyce , Foster Helen , Ioannou Yiannis , McErlane Flora , Wedderburn Lucy R. , Thomson W. , Hyrich Kimme L. 
Published: April 2018

ObjectivePotential targets for treat‐to‐target strategies in juvenile idiopathic arthritis are minimal disease activity (MDA) and clinically inactive disease (CID). We undertook this study to compare short‐ and long‐term outcomes following achievement of MDA and CID on the 10‐joint clinical Juvenile Arthritis Disease Activity Score (cJADAS10) and following achievement of CID on Wallace et al's preliminary criteria.MethodsChildren recruited to the Childhood Arthritis Prospective Study, a UK multicenter inception cohort, were selected if they were recruited prior to January 2011 and diagnosed as having oligoarthritis or rheumatoid factor–negative or –positive polyarthritis. One year following diagnosis, children were assessed for MDA on the cJADAS10 and for CID on both Wallace et al's preliminary criteria and the cJADAS10. Associations were tested between those disease states and functional ability, absence of joints with limited range of motion, psychosocial health, and pain at 1 year and annually to 5 years.ResultsOf 832 children, 70% were female and the majority had oligoarthritis (68%). At 1 year, 21% had achieved CID according to both definitions, 7% according to Wallace et al's preliminary criteria alone, and 16% according to the cJADAS10 alone; 56% had not achieved CID. Only 10% of children in the entire cohort achieved MDA without also achieving CID. Achieving either early CID state was associated with a greater absence of joints with limited range of motion. However, only CID according to the cJADAS10 was associated with improved functional ability and psychosocial health. Achieving CID was superior to achieving MDA in terms of short‐ and long‐term pain and the absence of joints with limited range of motion.ConclusionCID on the cJADAS10 may be preferable as a treatment target to CID on Wallace et al's preliminary criteria in terms of both feasibility of application and long‐term outcomes.
Monitoringgestützte Analyse von Schwingungsdämpfern in Turmbauwerken
Authors: Dragos Kosmas , Steiner Maria , Zabel Volkmar , Smarsly Kay 
Published: April 2018

AbstractSchlanke Bauwerke, wie Türme und Masten, zeigen oft ein unerwünschtes dynamisches Verhalten, wenn sie zeitlich veränderlichen Belastungen ausgesetzt sind. Eigenschwingungen höherer Ordnung sowie Resonanzphänomene zwischen den einwirkenden dynamischen Lasten und der Struktur können zu beträchtlichen Bauwerksschwingungen führen. Zur Reduzierung solcher Schwingungen werden häufig Schwingungsdämpfersysteme eingesetzt. Ein Schwingungsdämpfer ist ein Feder‐Masse‐Dämpfer‐System, dessen dynamische Eigenschaften so auf das Bauwerk abgestimmt sind, dass die Trägheitskräfte den Bauwerksschwingungen durch einen Phasenversatz der Relativbewegung zwischen Bauwerk und Schwingungsdämpfer optimal entgegenwirken und diese reduzieren. Die Bemessung von Schwingungsdämpfern erfolgt entweder auf Grundlage numerischer Berechnungen oder durch Schwingungsversuche zur Ermittlung der dynamischen Eigenschaften des Bauwerks. Während der Lebensdauer eines Bauwerks können sich jedoch die dynamischen Eigenschaften, beispielsweise aufgrund von Alterungsprozessen, ändern, sodass die Wirksamkeit der Schwingungsdämpfer herabgesetzt wird. Im vorliegenden Beitrag wird eine Methode zur Beurteilung der Wirksamkeit von Schwingungsdämpfern unter Verwendung von Daten aus einem Structural‐Health‐Monitoring‐(SHM‐)System vorgestellt. Die Funktionalität des Schwingungsdämpfers wird durch Betrachtung des Phasenversatzes zwischen den Schwingungen des Bauwerks und des Dämpfers untersucht, wobei ein optimaler Dämpfungseffekt bei einer Phasenverschiebung von annähernd 90° zwischen diesen beiden Schwingungsantworten erwartet wird. Die vorgeschlagene Methode wird am Beispiel eines mit Schwingungsdämpfer und SHM‐System versehenen Sendeturms validiert.
Using chemiluminescence to determine whole blood antioxidant capacity in rheumatoid arthritis and Parkinson's disease patients
Authors: Hughes Diane L. , Richards Ross S. , Lexis Louise A. 
Published: April 2018

AbstractThe consequences of oxidative stress and inflammation are implicated in a wide range of diseases, including rheumatoid arthritis and Parkinson's disease. The status of antioxidant capacity in rheumatoid arthritis and Parkinson's disease remains unclear, in part due to common practice of assaying erythrocytes separately to plasma. This method removes any synergistic interactions between plasma and erythrocyte‐based antioxidants. The experiments in this report tested antioxidant capacity in whole blood, erythrocytes and plasma by group and disease stage. Medically diagnosed patients were recruited along with appropriate control group participants. Fasting venous blood was assayed using chemiluminescence methods for: time to maximum light emitted, maximum light emitted, and plasma antioxidant capacity in vitamin E analogue units. Here we demonstrate that whole blood exhibits higher antioxidant capacity than either plasma or erythrocytes assayed separately. We report increased oxidative stress in the blood of rheumatoid arthritis patients by group (p = 0.018, p = 0.049). We show increased antioxidant capacity in Parkinson's disease patients by group (p < 0.001). For later stage Parkinson's disease patients, we report reduced oxidative stress (p = 0.025), and increased antioxidant capacity and for erythrocytes (p < 0.001, p = 0.004) and whole blood (p < 0.001, p = 0.003). Early stage Parkinson's disease showed higher antioxidant capacity on only one measure (p = 0.008). Whole blood chemiluminescence is a useful technique for determining redox status in disease and might help clarify the role of oxidative stress in rheumatoid arthritis and Parkinson's disease.
Potential of Pyridine Amphiphiles as Staphylococcal Nuclease Inhibitor
Authors: Sahareen Tabassum , Dey Poulomi , Mukherjee Sandipan , Das Gopal , Ramesh Aiyagari 
Published: April 2018

AbstractThe present study explores the potential of pyridine‐based synthetic amphiphiles C1 and C2 having 4‐carbon and 12‐carbon hydrophobic tails, respectively, as staphylococcal nuclease inhibitors. UV–visible titration with calf‐thymus DNA (CT‐DNA) revealed a hypochromic shift in the absorbance bands of C1 and C2, whereas fluorescence titration indicated a reduction in the emission intensity of the monomer bands of the amphiphiles. Interaction of deoxyribonuclease I (DNase 1) and micrococcal nuclease (MNase) with C1 or C2 led to a decrease in the emission intensity of tryptophan at λ=345 nm along with an increase in the monomer emission intensity of C1 and C2 at λ=375 nm for DNase I and excimer emission intensity at λ=470 nm for both DNase I and MNase. Scatchard's analysis indicated superior interaction of C2 with DNase I. Circular dichroism spectroscopy revealed major changes in the secondary structures of both DNase I and MNase upon interaction with the amphiphiles. A solution‐based nuclease assay in conjunction with gel electrophoresis indicated amphiphile‐mediated protection against nuclease‐directed DNA cleavage. Interestingly, C2 could render inhibition of nuclease present in the culture supernatant of Staphylococcus aureus MTCC 96, which highlights the therapeutic prospect of the amphiphile against S. aureus.
A Genetically Encoded Ratiometric pH Probe: Wavelength Regulation‐Inspired Design of pH Indicators
Authors: Berbasova Tetyana , Tahmasebi Nick Setare , Nosrati Meisam , Nossoni Zahra , Santos Elizabeth M. , Vasileiou Chrysoula , Geiger James H. , Borhan Babak 
Published: April 2018

AbstractMutants of human cellular retinol‐binding protein II (hCRBPII) were engineered to bind a julolidine retinal analogue for the purpose of developing a ratiometric pH sensor. The design relied on the electrostatic influence of a titratable amino acid side chain, which affects the absorption and, thus, the emission of the protein/fluorophore complex. The ratio of emissions obtained at two excitation wavelengths that correspond to the absorption of the two forms of the protein/fluorophore complex, leads to a concentration‐independent measure of pH.
Collision Characteristics for Predicting Particle Attrition and Pipe Wear in Conveying Systems
Authors: Uzi Avi , Levy Avi 
Published: April 2018

AbstractPipe wear and particle attrition are common and undesired effects when conveying particles in pipelines. An approach for predicting these effects to spare considerable efforts spent in trial and error to achieve the optimum operating conditions is reported. The model is composed of a one‐dimensional flow model that calculates the two‐phase flow dynamics, a one‐dimensional breakage algorithm (ODBA) to compute attrition of the particles, and a one‐dimensional erosion model (ODEM) to compute the erosion rate. The ODBA and ODEM exploit machine functions derived from simulations that define collision characteristics. Several collision characteristics were successfully generated universally; therefore, allowing the attrition and erosion models to stand alone in the examined ranges.
Multistage Processing of Tunable Aqueous Polymer Phase Impregnated Resins (TAPPIR®)
Authors: Kaplanow Irene , Stecker Joel , Schembecker Gerhard , Merz Juliane 
Published: April 2018

AbstractA promising concept of aqueous two‐phase extraction (ATPE) is the Tunable Aqueous Polymer Phase Impregnated Resins (TAPPIR®) technology. Thereby, one phase of an aqueous two‐phase system (ATPS) is immobilized inside porous solids, which are then dispersed in the second aqueous phase. Beside extraction performance, the reusability of the impregnated solids for several cycles decides upon the competitiveness of TAPPIR®. Multistage extraction experiments using a polyethylene glycol 4000/citrate ATPS to partition lysozyme were investigated for TAPPIR® and ATPE. A stable impregnation was demonstrated for multiple cycles. Moreover, it was found that multistage extraction processes should not be designed on basis of the first extraction as the yield changes in the following stages.
Hydration of Concrete: The First Steps
Authors: Thissen Peter , Natzeck Carsten , Giraudo Nicolas , Weidler Peter , Wöll Christof 
Published: April 2018

AbstractConcrete is the most important construction material used by mankind and, at the same time, one of the most complex substances known in materials science. Since this mineral compound is highly porous, a better understanding of its surface chemistry, and in particular the reaction with water, is urgently required to understand and avoid corrosion of infrastructure like buildings and bridges. We have gained insight into proton transfer from concrete upon contact with water by applying the so‐called Surface Science approach to a well‐defined mineral, Wollastonite. Data from IR (infrared) spectroscopy reveal that exposure of this calcium‐silicate (CS) substrate to H2O leads to dissociation and the formation of OH‐species. This proton transfer is a chemical reaction of key importance, since on the one hand it triggers the conversion of cement into concrete (a calcium‐silicate‐hydrate phase), but on the other hand also governs the corrosion of concrete. Interestingly, we find that no proton transfer takes place when the same surface is exposed to methanol. In order to understand this unexpected difference, the analysis of the spectroscopic data obtained was aided by a detailed, first‐principles computational study employing density functional theory (DFT). The combined experimental and theoretical effort allows derivation of a consistent picture of proton transfer reactions occurring in CS and CSH phases. Implications for strategies to protect this backbone of urban infrastructure from corrosion in harsh, aqueous environments will be discussed.
In Situ Fabrication of Hierarchical MTW Zeolite via Nanoparticle Assembly by a Tailored Simple Organic Molecule
Authors: Zhang Kai , Luo Shaojuan , Liu Zewei , Li Chao , Ke Zheng , Yan Xin , Wu Ying , Xi Hongxia 
Published: April 2018

AbstractAmphiphilic surfactants are widely used as templates to synthesize hierarchically structured zeolites due to their multiple functions; however, piloting such new dual‐functional templates is limited by their time‐consuming nature and high cost. Herein, a simple organic molecule, without a long hydrophobic alkyl chain, was tailored from a gemini‐type, poly‐quaternary ammonium surfactant, and effectively used as a dual‐porogenic template to synthesize hierarchical MTW zeolite. Upon a range of synthesis parameter optimizations, our detailed characterization suggested that the hierarchical MTW zeolite would completely crystallize within 36 hours from the surface to the inside of quasi—spherical particles through in situ consumption of amorphous silicon and aluminum species; much faster than most of the hierarchical MTW zeolites generated by conventional methods. Moreover, the as‐prepared hierarchical MTW zeolite exhibited 4 times higher catalytic performance and lifetime of benzene‐propene alkylation compared to conventional MTW zeolite, while the introduced crystalline mesopores are of benefit to diffuse reactants, products, and coke depositions. Our strategy broadens the design of new templates in more effective ways to facilely synthesize versatile hierarchical zeolites for diverse applications, especially for those in which macromolecules are involved.
Of Thiols and Disulfides: Methods for Chemoselective Formation of Asymmetric Disulfides in Synthetic Peptides and Polymers
Authors: Schäfer Olga , Barz Matthias 
Published: April 2018

AbstractIn protein or peptide chemistry, thiols are frequently chosen as a chemical entity for chemoselective modification reactions. Although it is a well‐established methodology to address cysteines and homocysteines in aqueous media to form S−C bonds, possibilities for the chemoselective formation of asymmetric disulfides have been less approached. Focusing on bioreversibility in conjugation chemistry, the formation of disulfide bonds is highly desirable for the attachment of thiol‐containing bioactive agents to proteins or in cross‐linking reactions, because disulfide bonds can combine stability in blood with degradability inside cells. In this Concept article, recent approaches in the field of activating groups for thiol moieties incorporated in peptide and polymer materials are highlighted. Advantageous combinations of stability during synthesis of the material with high reactivity towards thiols are explored focusing on simplification and prevention of side reactions as well as additional deprotection and activation steps prior to disulfide formation. Moreover, applications of this chemistry are highlighted and future perspectives are envisioned.
A General One‐Pot Synthesis of 2H‐Indazoles Using an Organophosphorus–Silane System
Authors: Schoene Jens , Bel Abed Hassen , Schmieder Peter , Christmann Mathias , Nazaré Marc 
Published: April 2018

AbstractA simple and direct approach for the regioselective construction of the privileged 2H‐indazole scaffold is described. The developed one‐pot strategy involves phospholene‐mediated N−N bond formation to access 2H‐indazoles. The amount of organophosphorus reagent was minimized by recycling the phospholene oxide with organosilane reductants. Starting from functionalized 2‐nitrobenzaldehydes and primary amines, a mild reductive cyclization, involving the use of commercially available phospholene oxide and silanes, delivered a wide variety of substituted 2H‐indazoles in good to excellent yields.
Multidentate Phosphanyl Phosphinines: Synthesis and Properties
Authors: Chen Xiaodan , Li Zhongshu , Grützmacher Hansjörg 
Published: April 2018

AbstractWith respect to the well‐developed chemistry of pyridines, that of phosphinines is in its infancy. There are still challenges to be overcome with respect to the development of simple syntheses and the application of phosphinine derivatives. Here, we show that sodium phosphinin‐2‐olate is a valuable building block to prepare multidentate phosphinine ligands, which in turn can be employed for the preparation of metal complexes. These PdII and RhI complexes were fully characterized, including by NMR spectra and single‐crystal X‐ray diffraction studies, which clearly demonstrate that molecules R3−xP(O‐phosphinine)x with one, two, and three phosphinines (x=1, 2, 3) can be tethered to a central phosphorus donor center to give bis‐, tris‐, and tetradentate ligands.
Carboxylates as Nucleophiles in the Enantioselective Ring‐Opening of Formylcyclopropanes under Iminium Ion Catalysis
Authors: Díaz Estibaliz , Reyes Efraim , Uria Uxue , Carrillo Luisa , Tejero Tomas , Merino Pedro , Vicario Jose L. 
Published: April 2018

AbstractIn this work, carboxylic acids, which are typically regarded as poor nucleophiles, are demonstrated to be competent reagents to promote the ring‐opening of formylcyclopropanes after activation of the latter through iminium ion formation. Under optimized reaction conditions, a variety of γ‐acyloxy‐substituted aldehydes can be obtained in high yields and enantioselectivities through the desymmetrization of substituted meso‐formylcyclopropanes in the presence of a chiral secondary amine as catalyst.
Hydrazo‐CEST: Hydrazone‐Dependent Chemical Exchange Saturation Transfer Magnetic Resonance Imaging Contrast Agents
Authors: Dang Trina , Suchy Mojmír , Truong Yen J. , Oakden Wendy , Lam Wilfred W. , Lazurko Caitlin , Facey Glenn , Stanisz Greg J. , Shuhendler Adam J. 
Published: April 2018

AbstractThe rapid formation of hydrazones under physiological conditions was exploited for the detection of aldehydes through chemical exchange saturation transfer magnetic resonance imaging (CEST‐MRI). A metal‐free, diamagnetic contrast agent derived from N‐amino anthranilic acid was introduced, which selectively “turned‐on” upon hydrazone formation through an effect termed Hydrazo‐CEST. While the hydrazine form of the probe produced no CEST‐MRI signal enhancement, the formation of the aryl hydrazone resulted in >20 % intensity decrease in the bulk water signal through the CEST effect, as measured by 300 MHz 1H NMR, 3 T and 7 T MRI. Both the electronic contributions of the N‐amino anthranilate and the aldehyde binding partner were shown to directly impact the exchange rate of the proton on the ring‐proximal nitrogen, and thus the imaging signal. Additionally, the presence of the carboxylic acid moiety ortho to the hydrazine was necessary not only for contrast production, but also for rapid hydrazone formation and prolonged hydrazone product stability under physiological conditions. This work provided the first example of an MRI‐based contrast agent capable of a “turn on” response upon reaction with bioactive aldehydes, and outlined both the structural and electronic requirements to expand on Hydrazo‐CEST, a novel, hydrazone‐dependent subtype of diamagnetic CEST‐MRI.
Improving therapy for patients with epidermal growth factor receptor‐mutant lung cancer
Authors: Arbour Kathryn C. , Riely Gregory J. 
Published: April 2018

Progress in the rational development of therapy for patients with epidermal growth factor receptor‐mutant lung cancer depends on pursuing multiple parallel approaches to the problem of resistance. New treatment strategies evaluating not only new drugs, but also novel dosing strategies and novel combinations based on off‐target mechanisms of resistance and general principles of tumor biology, have great potential to improve treatments for patients with epidermal growth factor receptor‐mutant lung cancer.See also pages 2355‐64, this issue.