bluuebunny/crossref_metadata_2025_split huggingface dataset:
Computational and Synthetic Investigation of Cationic Rearrangement in the Putative Biosynthesis of Justicane Triterpenoids
Authors: Elkin Masha , Scruse Anthony C. , Turlik Aneta , Newhouse Timothy R. 
Published: December 2018

AbstractA biomimetic cationic structural rearrangement of the oleanolic acid framework is reported for the gram‐scale synthesis and structural reassignment of justicioside E aglycone. The mechanism of the putative biosynthetic rearrangement is investigated with kinetic, computational, and synthetic approaches. The precursor to rearrangement was accessed through two strategic advancements: (1) synthesis of a 1,3‐diketone via oxidation of a β‐silyl enone, and (2) diastereoselective 1,3‐diketone reduction to form a syn‐1,3‐diol using SmI2 with PhSH as a key additive.
Ideal‐Filter Capillary Electrophoresis (IFCE) Facilitates the One‐Step Selection of Aptamers
Authors: Le An T. H. , Krylova Svetlana M. , Kanoatov Mirzo , Desai Shrey , Krylov Sergey N. 
Published: December 2018

AbstractSelection of aptamers from oligonucleotide libraries currently requires multiple rounds of alternating steps of partitioning of binders from nonbinders and enzymatic amplification of all collected oligonucleotides. Herein, we report a highly practical solution for reliable one‐step selection of aptamers. We introduce partitioning by ideal‐filter capillary electrophoresis (IFCE) in which binders and nonbinders move in the opposite directions. The efficiency of IFCE‐based partitioning reaches 109, which is ten million times higher than that of typical solid‐phase partitioning methods. One step of IFCE‐based partitioning is sufficient for the selection of a high‐affinity aptamer pool for a protein target. Partitioning by IFCE promises to become an indispensable tool for fast and robust selection of binders from different types of oligonucleotide libraries.
Total Synthesis of (−)‐Merochlorin A
Authors: Brandstätter Marco , Freis Manuel , Huwyler Nikolas , Carreira Erick M. 
Published: December 2018

AbstractThe first asymmetric total synthesis of the meroterpenoid (−)‐merochlorin A is described. The route features enantiospecific gold‐catalyzed tandem 1,3‐acyloxy migration/Nazarov/aldol reaction sequence to furnish the bicyclo[3.3.0]octane core in a single step from a linear propargylic 1,3‐enyne aldehyde. After completion of the central skeleton by reductive enol lactone rearrangement, late stage Diels–Alder cycloaddition/aromatization sequence installed the resorcinol. An additional salient feature of the synthesis is the assignment of the absolute configuration, which had not been determined previously.
A Water‐Soluble Perylene Bisimide Cyclophane as a Molecular Probe for the Recognition of Aromatic Alkaloids
Authors: Sapotta Meike , Hofmann Anja , Bialas David , Würthner Frank 
Published: December 2018

AbstractHerein, we report a water‐soluble macrocyclic host based on perylene bisimide (PBI) chromophores that recognizes natural aromatic alkaloids in aqueous media by intercalating them into its hydrophobic cavity. The host–guest binding properties of our newly designed receptor with several alkaloids were studied by UV/Vis and fluorescence titration experiments as the optical properties of the chromophoric host change significantly upon complexation of guests. Structural information on the host–guest complexes was obtained by 1D and 2D NMR spectroscopy and molecular modelling. Our studies reveal a structure–binding property relationship for a series of structurally diverse aromatic alkaloids with the new receptor and higher binding affinity for the class of harmala alkaloids. To our knowledge, this is the first example of a chromophoric macrocyclic host employed as a molecular probe for the recognition of aromatic alkaloids.
Optimization of ethylene trimerization using catalysts based on TiCl3/half‐sandwich ligands
Authors: Azimnavahsi Leila , Mohamadnia Zahra 
Published: December 2018

Catalytic trimerization of ethylene using three titanium‐based complexes [η5‐C9H6C(R)thienyl]TiCl3 with various types of bridges (R = cyclo‐C5H10 (C1), cyclo‐C4H8 (C2) and (CH3)2 (C3)) has been successfully optimized and compared. First of all, three benzofulvene precursors, C9H6C(R), were synthesized. Then the corresponding indenyl‐based ligands were obtained via the reaction of the precursors with thienyllithium. The final titanium‐based catalysts display a distorted tetrahedral geometry, as expected for Ti(IV), with the ligand coordinated with a hemilabile behaviour. The structures of the compounds were confirmed on the basis of various analyses. The effect of catalyst concentration, ethylene pressure, reaction temperature and nature of the bridge as the significant factor affecting coordination and orientation of thienyl group relative to the metal centre on 1‐hexene (1‐C6) productivity and selectivity was investigated. Results revealed that the bulky bridge groups such as cyclo‐C5H10 and cyclo‐C4H8 are appropriate for ethylene trimerization due to the closer coordination of sulfur atom with Ti, especially in cationic state, and catalyst C2 with cyclo‐C4H8 bridge exhibits moderate productivity equal to 785 kg 1‐C6 (mol Ti)−1 h−1. According to the results, ethylene at a pressure of 10 bar, 50°C and 1.5 μmol of catalyst were selected as the best conditions for obtaining 1‐C6 with high productivity and selectivity. The presence of indenyl enhances the thermal stability of the catalysts and preserves their activity in higher temperatures such as 50 and 80°C.
C–C bridged Ni(II) complexes bearing β‐keto‐9‐fluorenyliminato ligands prepared by different in situ bonding mechanisms and their use in catalytic (co)polymerization of norbornene and styrene
Authors: He Xiaohui , Wang Suli , Yang Yingping , Tu Guangshui , Zhang Feng , Huang Shengmei , Duan Yapeng , Zhu Chuanyi , Cheng Changwen , Chen Defu 
Published: December 2018

Two C–C bridged Ni(II) complexes bearing β‐keto‐9‐fluorenyliminato ligands with electron‐withdrawing groups (─CF3), Ni{PhC(O)CHC[N(9‐fluorenyl)]CF2}2 (Ni1) and Ni{CF3C(O)CHC[N(9‐fluorenyl)]Ph}2 (Ni2), were synthesized by metal coordination reaction and different in situ bonding mechanisms. The C–C bridged bonds of Ni1 were formed by in situ intramolecular trifluoromethyl and 9‐fluorenyl carbon–carbon cross‐coupling reaction and those of Ni2 were formed by in situ intramolecular 9‐fluorenyl carbon–carbon radical coupling reaction mechanism. The obtained complexes were characterized using 1H NMR spectroscopy and elemental analyses. The crystal and molecular structures of Ni1 and Ni2 with C–C bridged configuration were determined using X‐ray diffraction. Ni1 and Ni2 were used as catalysts for norbornene (NB) polymerization after activation with B(C6F5)3 and the catalytic activities reached 106 gpolymer molNi−1 h−1. The copolymerization of NB and styrene catalyzed by the Ni1/B(C6F5)3 system showed high activity (105 gpolymer molNi−1 h−1) and the catalytic activities decreased with increasing feed content of styrene. All vinyl‐type copolymers exhibited high molecular weight (104 g mol−1), narrow molecular weight distribution (Mw/Mn = 1.71–2.80), high styrene insertion ratios (11.13–50.81%) and high thermal stability (Td > 380°C) and could be made into thin films with high transparency in the visible region (400–800 nm).
A gene expression signature‐based nomogram model in prediction of breast cancer bone metastases
Authors: Zhao Chenglong , Lou Yan , Wang Yao , Wang Dongsheng , Tang Liang , Gao Xin , Zhang Kun , Xu Wei , Liu Tielong , Xiao Jianru 
Published: December 2018

AbstractBreast cancer is prone to form bone metastases and subsequent skeletal‐related events (SREs) dramatically decrease patients’ quality of life and survival. Prediction and early management of bone lesions are valuable; however, proper prognostic models are inadequate. In the current study, we reviewed a total of 572 breast cancer patients in three microarray data sets including 191 bone metastases and 381 metastases‐free. Gene set enrichment analysis (GSEA) indicated less aggressive and low‐grade features of patients with bone metastases compared with metastases‐free ones, while luminal subtypes are more prone to form bone metastases. Five bone metastases‐related genes (KRT23, REEP1, SPIB, ALDH3B2, and GLDC) were identified and subjected to construct a gene expression signature‐based nomogram (GESBN) model. The model performed well in both training and testing sets for evaluation of breast cancer bone metastases (BCBM). Clinically, the model may help in prediction of early bone metastases, prevention and management of SREs, and even help to prolong survivals for patients with BCBM. The five‐gene GESBN model showed some implications as molecular diagnostic markers and therapeutic targets. Furthermore, our study also provided a way for analysis of tumor organ‐specific metastases. To the best of our knowledge, this is the first published model focused on tumor organ‐specific metastases.
A Topologically Distinct Modified Peptide with Multiple Bicyclic Core Motifs Expands the Diversity of Microviridin‐Like Peptides
Authors: Roh Heejin , Han Yeji , Lee Hyunbin , Kim Seokhee 
Published: December 2018

AbstractMicroviridins are ribosomally synthesized and post‐translationally modified peptides (RiPPs) that contain multiple intramolecular ω‐ester or ω‐amide crosslinks between two side chains in peptides. This type of the side‐to‐side macrocyclization may generate diverse structures with distinct topology and ring sizes, but the majority of the microviridin‐like RiPPs present only a single consensus sequence with a tricyclic architecture. Here, we expanded the natural diversity of the microviridin‐like modified peptides by determining the crosslinking connectivity of a new modified peptide, mTgnA and its homologous RiPPs, which we named the thuringinin group. Members of the thuringinin group have core motifs with a distinct consensus sequence, which is transformed to a novel hairpin‐like bicyclic structure by the cognate ATP‐grasp enzyme. We suggest that the microviridin‐like RiPPs naturally have novel sequences and architectures beyond those found in microviridins and comprise a larger RiPP family, termed omega‐ester containing peptides (OEPs).
DNA‐Based Chemical Reaction Networks
Authors: Li Fan , Xiao Mingshu , Pei Hao 
Published: December 2018

AbstractMotivated by complex molecular networks of biological organisms, which enable control of the temporal and spatial concentrations of molecules, the bottom‐up development of artificial chemical reaction networks has received renewed interest from biochemists. Based on hybridization and strand‐displacement reactions, DNA‐based chemical reaction networks (D‐CRNs) provide a promising method to describe and analyze (bio)chemical systems, depending on their high programmability and directionality. Herein, progress in the development of D‐CRNs is discussed, and an overview of significant biochemistry applications based on D‐CRNs reported in recent decades is provided. Furthermore, opportunities and future directions for research into D‐CRNs in biochemistry are also discussed.
Oxovanadium(V)‐Catalyzed Direct Amination of Allyl Alcohols
Authors: Sakuramoto Takashi , Hirao Toshikazu , Tobisu Mamoru , Moriuchi Toshiyuki 
Published: December 2018

AbstractDirect amination of allyl alcohols is regarded as one of reliable methods to synthesize allyl amines in one step because water is only by‐product. Oxovanadium(V) compound with triphenyl siloxide ligands was demonstrated to serve as an efficient catalyst in the direct amination of allyl alcohols. The catalytic direct amination reaction could be performed with both aromatic and aliphatic amines. This catalytic system induced selective direct amination in the case of the unsymmetrically substituted allyl alcohols. Furthermore, gram‐scale direct amination reaction was successfully achieved.
Hydrogenation Size‐Selective Pt/Hollow Beta Catalysts
Authors: Morgado Prates Ana Rita , Meunier Frédéric , Dodin Mathias , Martinez Franco Raquel , Farrusseng David , Tuel Alain 
Published: December 2018

AbstractThe aim of the present work is to synthesize a zeolite‐based catalyst with a hollow morphology and highly dispersed metal nanoparticles (NPs) encapsulated inside the zeolite micropores. For this purpose, we have studied a treatment using tetraalkylammonium (TAA) bromides for the selective removal of a large Pt particle from the outer surface of a hollow Beta zeolite. TEM analysis reveals that we succeeded in the synthesis of a hollow beta zeolite single crystal with encapsulated particles, with a high dispersion of 50–60 %. The molecular‐sieve‐type mechanism of the obtained catalysts was evaluated in the model reaction of toluene and mesitylene catalytic hydrogenation. Thanks to the high dispersion. a 10‐fold activity enhancement has been obtained with respect to hollow beta zeolites with encapsulated NPs recently described in the literature.
Tris(trichlorosilyl)tetrelide Anions and a Comparative Study of Their Donor Qualities
Authors: Teichmann Julian , Kunkel Chantal , Georg Isabelle , Moxter Maximilian , Santowski Tobias , Bolte Michael , Lerner Hans‐Wolfram , Bade Stefan , Wagner Matthias 
Published: December 2018

AbstractTrichlorosilylated tetrelides [(Cl3Si)3E]− have been prepared by adding 1 equiv of a soluble Cl− salt to (Cl3Si)4Si (E=Si) or 4 Si2Cl6/GeCl4 (E=Ge). To assess their donor qualities, the anions [(Cl3Si)3E]− (E=C, Si, Ge) have been treated with BCl3, AlCl3, and GaCl3. Both BCl3 and GaCl3 give 1:1 adducts with the anionic centers. AlCl3 leads to Cl− abstraction from [(Cl3Si)3E]− with formation of (Cl3Si)4E (E=Si or Ge). (Cl3Si)4Ge is cleanly converted to the perhydrogenated (H3Si)4Ge by use of Li[AlH4]. Another case of Cl− abstraction was observed for [(Cl3Si)3Ge⋅GaCl3]−, which reacts with GaCl3 to afford the neutral dimer [(Cl3Si)3Ge−GaCl2]2.
Improvement of the ON/OFF Switching Performance of a pH‐Activatable Porphyrin Derivative by the Introduction of Phosphorus(V)
Authors: Horiuchi Hiroaki , Isogai Masataka , Hirakawa Kazutaka , Okutsu Tetsuo 
Published: December 2018

AbstractAn activatable photosensitizer for singlet oxygen is of significance due to its potential application in tumor‐specific photodynamic therapy and diagnosis. In this study, a pH‐activatable system that enables the specific photosensitization of singlet oxygen at a low pH value was developed based on the complexation of a porphyrin‐aniline conjugate with phosphorus(V). As a result of complexation with phosphorus, the water solubility of the porphyrin‐aniline conjugate was improved 100‐fold. Furthermore, this complexation strongly suppressed the singlet‐oxygen‐generating activity of the porphyrin photosensitizer under basic conditions, and the quantum yield of the singlet oxygen photosensitization markedly increased under acidic conditions. Based on these improvements, an extremely high ON/OFF switching ratio of the quantum yield was obtained (>400‐fold).
A Reproducible, Objective Method Using MitoTracker® Fluorescent Dyes to Assess Mitochondrial Mass in T Cells by Flow Cytometry
Authors: Clutton Genevieve , Mollan Katie , Hudgens Michael , Goonetilleke Nilu 
Published: December 2018

AbstractMitoTracker ® dyes are fluorescent compounds that allow cellular mitochondrial content to be measured semi‐quantitatively by flow cytometry and have been used extensively in immunology publications. However, the parameters commonly reported, mean or median fluorescence intensity and percentage of cells that are MitoTracker® “high”, can be influenced by variability in cytometer setup, dye stability, and operator subjectivity, making it difficult to compare data between experiments. Here, we describe a method to identify MitoTracker® “high” populations in an objective manner. When analyzing data, we first removed outliers using a pre‐specified threshold, determined the fluorescence intensity of the brightest and dimmest events to obtain the fluorescence range and then gated cells within the top 90% of this range. This strategy substantially reduced variability between technical replicates and produced consistent results when data were analyzed by different operators. Consistent with previous reports and other analysis strategies, this analysis method demonstrated that within an individual, CD4+ T cells exhibit significantly higher mitochondrial mass than CD8+ T cells. Objective gating increases the reliability and utility of data generated using MitoTracker® dyes. © 2018 The Authors. Cytometry Part A published by Wiley Periodicals, Inc. on behalf of International Society for Advancement of Cytometry.
Impact of operating parameters and wall material components on the characteristics of microencapsulated Melissa officinalis essential oil
Authors: Karimi Sani Iraj , Alizadeh Mohammad , Pirsa Sajad , Moghaddas Kia Ehsan 
Published: December 2018

AbstractTo develop a novel usage for functional essential oils, the present study aimed to evaluate the influence of process parameters on the characteristics of Melissa officinalis essential oil microencapsulated through whey protein isolate (WPI) and sodium caseinate (NaCS). Melissa officinalis was encapsulated via whey proteins and NaCS with variable ratios (0–100), core/coating ratios (10–100%), and ultrasonication power (50–150). The impacts of these variables were examined via response surface methodology. The findings demonstrated that lower particle sizes were obtained at higher amounts of WPI with the lowest level of applied sonication power. Desirability function results indicate that the maximum quantity of WPI with an ultrasonication power of 50 W led to the lowest particle size, zeta potential, and turbidity. The application of microcapsules loaded with Melissa officinalis was found to be useful to preserve their bioactive compounds and induces flavour stability, enabling the use of microcapsules in food formulations.
Long‐term marginal adaptation and nanoleakage of class V cavity restored with organic filler filled 4‐META/MMA‐TBB resin
Authors: Zhang Chao , Yang Bin 
Published: December 2018

AbstractThe current restorative materials used for cervical lesions restoration still need to be improved. A low E‐modulus restorative material Bondfill SB (group BF) is developed. This study was to evaluate marginal adaptation and nanoleakage expression at dentin bonding interface of BF before and after artificial aging cycling when used for class V cavity restoration in vitro. Cavities were prepared in human premolars and restored with either Bondfill SB or Z100 (group SZ). Quantitative data were analyzed by t‐test (α = 0.05). Before cycling, there was no significant differences between groups for perfect margin and modes of failure. After cycling, SZ showed a higher (p = 0.002) perfect margin value (55.08 ± 15.20%) and less (p = 0.01) adhesive failure (35.35 ± 15.02%) to enamel than BF (25.15 ± 12.47% and 61.78 ± 15.41%, respectively). BF exhibited less (p = 0.01) adhesive failure (12.89 ± 5.58%) to dentin than SZ (44.17 ± 17.50%). BF showed more cohesive failures at both enamel (12.01 ± 3.65%) (p < 0.0001) and dentin (9.58 ± 3.14%) (p = 0.02) sides than SZ (0.77 ± 1.21% and 4.68 ± 1.39%, respectively). Transmission electron microscope (TEM) showed that hybrid layers in SZ and BF were around 0.5 μm thick. Before cycling, more silver deposits were found at dentin bonding interface in SZ. After cycling, the deterioration in SZ mostly occurred at the bottom and on the surface of the hybrid layer. While in BF, the deterioration occurred at the bottom of the hybrid layer and in Bondfill SB. BF showed a more reliable dentin bonding after artificial aging and might buffer the cervical stress concentration. Bondfill SB may be a new promising choice for long‐term success of cervical lesions restoration. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2050–2056, 2019.
Novel zein‐based multilayer wound dressing membranes with controlled release of gentamicin
Authors: Kimna Ceren , Tamburaci Sedef , Tihminlioglu Funda 
Published: December 2018

AbstractRecently, functional multilayer scaffolds with controlled drug release ability come into prominence for wound healing applications to mimic the layered structure of skin tissue and prevent the possible infections at the defect site. In this study, controlled antibiotic releasing zein bilayer membranes were fabricated for treatment of acute skin infections. Gentamicin loaded fibers were prepared by electrospinning on the membrane surface. Membranes were characterized with scanning electron microscope, atomic force microscopy, Fourier transform infrared spectroscopy, contact angle, mechanical analysis, swelling, degradation, and water vapor permeability studies. In vitro cytotoxicity, cell attachment, and proliferation were investigated. Cell attachment on fiber layer was observed with fluorescence imaging. Fabricated fibers showed structural similarity to the skin tissue layers with a fiber diameter range of 350–425 nm and film thickness in the range of 311–361 μm. Mechanical properties were found compatible with the skin tissue. In addition, membranes showed antimicrobial activity against Staphylococcus aureus and Escherichia coli. The sustained release was achieved with a cumulative release of 94%. Membranes did not show any cytotoxic effect. NIH/3T3 and HS2 cell lines were proliferated on each layer mimicking the multilayer skin tissue. Hence, zein‐based bilayer membrane showed promising properties to be used as a potential antimicrobial wound dressing for skin tissue regeneration. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2057–2070, 2019.
Global secretome analysis of resident cardiac progenitor cells from wild‐type and transgenic heart failure mice: Why ambience matters
Authors: Samal Rasmita , Sappa Praveen Kumar , Gesell Salazar Manuela , Wenzel Kristin , Reinke Yvonne , Völker Uwe , Felix Stephan Burkhard , Hammer Elke , Könemann Stephanie 
Published: December 2018

AbstractResident cardiac progenitor cells (CPCs) have gained attention in cardiac regenerative medicine primarily due to their paracrine activity. In our current study we determined the role of pathological conditions such as heart failure on the autocrine‐paracrine action of stem cell antigen‐1 (Sca‐1) expressing CPC. This comparative secretome profiling of Sca‐1+ cells derived from transgenic heart failure (αMHC–cyclin‐T1/Gαq overexpression [Cyc] cells) versus healthy (wild‐type [Wt] cells) mice, achieved via mass‐spectrometric quantification, enabled the identification of over 700 proteins. Our results demonstrate that the heart failure milieu caused a 2‐fold enrichment of extracellular matrix proteins (ECM) like biglycan, versican, collagen XII, and angiogenic factors like heparan sulfate proteoglycan 2, plasminogen activator inhibitor 1 in the secretome. We further elucidated the direct influence of the secretome on the functional behavior of Sca‐1
+ cells via in vitro tube forming assay. Secreted factors present in the diseased milieu induced tube formation in Cyc cells (1.7‐fold;
p < 0.01) when compared with Wt cells after 24 hr of exposure. The presence of conditioned media moderately increased the proliferation of Cyc cells but had a more pronounced effect on Wt cells. Overall, these findings revealed global modifications in the secretory activity of adult Sca‐1
+ cells in the heart failure milieu. The secretion of ECM proteins and angiogenic factors, which are crucial for cardiac remodeling and recovery, was notably enriched in the supernatant of Cyc cells. Thus, during heart failure the microenvironment of Sca‐1
+ cells might favor angiogenesis and proliferation suggesting their potential to recover the damaged heart.