bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electro‐Oxidative S−H/S−H Cross‐Coupling with Hydrogen Evolution: Facile Access to Unsymmetrical Disulfides
Authors: Huang Pengfei , Wang Pan , Tang Shan , Fu Zhuangjiong , Lei Aiwen 
Published: May 2018

AbstractSulfur is an essential element because it exists widely in proteins. The disulfide bond is an important moiety in many different types of significant organic molecules. A new approach for oxidant‐ and catalyst‐free S−H/S−H cross‐coupling, with hydrogen evolution, to construct unsymmetrical disulfides was developed. Under the conditions of an undivided cell at room temperature, a series of unsymmetrical disulfides were prepared with up to 87 % yield from the direct coupling of an aryl mercaptan and alkyl mercaptan. Gram‐scale synthesis also highlights the synthetic utility of this electrochemical strategy.
Effective Assignment of α2,3/α2,6‐Sialic Acid Isomers by LC‐MS/MS‐Based Glycoproteomics
Authors: Pett Christian , Nasir Waqas , Sihlbom Carina , Olsson Britt‐Marie , Caixeta Vanessa , Schorlemer Manuel , Zahedi René P. , Larson Göran , Nilsson Jonas , Westerlind Ulrika 
Published: May 2018

AbstractDistinct structural changes of the α2,3/α2,6‐sialic acid glycosidic linkages on glycoproteins are of importance in cancer biology, inflammatory diseases, and virus tropism. Current glycoproteomic methodologies are, however, not amenable toward high‐throughput characterization of sialic acid isomers. To enable such assignments, a mass spectrometry method utilizing synthetic model glycopeptides for the analysis of oxonium ion intensity ratios was developed. This method was successfully applied in large‐scale glycoproteomics, thus allowing the site‐specific structural characterization of sialic acid isomers.
Highly Productive Oxidative Biocatalysis in Continuous Flow by Enhancing the Aqueous Equilibrium Solubility of Oxygen
Authors: Chapman Michael R. , Cosgrove Sebastian C. , Turner Nicholas J. , Kapur Nikil , Blacker A. John 
Published: May 2018

AbstractWe report a simple, mild, and synthetically clean approach to accelerate the rate of enzymatic oxidation reactions by a factor of up to 100 when compared to conventional batch gas/liquid systems. Biocatalytic decomposition of H2O2 is used to produce a soluble source of O2 directly in reaction media, thereby enabling the concentration of aqueous O2 to be increased beyond equilibrium solubility under safe and practical conditions. To best exploit this method, a novel flow reactor was developed to maximize productivity (g product L−1 h−1). This scalable benchtop method provides a distinct advantage over conventional bio‐oxidation in that no pressurized gas or specialist equipment is employed. The method is general across different oxidase enzymes and compatible with a variety of functional groups. These results culminate in record space‐time yields for bio‐oxidation.
Shadow Mask Templates for Site‐Selective Metal Exchange in Magnesium Porphyrin Nanorings
Authors: Bols Pernille S. , Anderson Harry L. 
Published: May 2018

AbstractMolecular templates can be used in many different ways to control the outcome of chemical reactions. Herein, we present a new type of template‐directed synthesis. We show that templates can be used as shadow masks: The shape of the template becomes imprinted on the product because reactions only occur at sites not masked by the template. We demonstrate this effect by using oligopyridine templates to dictate the sites of demetalation when a magnesium porphyrin nanoring is treated with acid. Magnesium centers that are coordinated to the template are protected whereas uncoordinated magnesium centers are removed. After site‐selective demetalation, the template can be removed, and other cations, such as zinc(II) and copper(II), can be inserted into the free‐base porphyrin centers. This strategy provides a simple route to a wide range of heterometalated porphyrin arrays.
Electrophilic Formylation of Arenes by Silylium Ion Mediated Activation of Carbon Monoxide
Authors: Omann Lukas , Qu Zheng‐Wang , Irran Elisabeth , Klare Hendrik F. T. , Grimme Stefan , Oestreich Martin 
Published: May 2018

AbstractArene‐stabilized silylium ions react with carbon monoxide rather than carbon monoxide adducts of silylium ions reacting with arenes. This mechanism is supported by quantum‐chemical calculations. Even sterically hindered mesitylene and electronically deactivated chlorobenzene engage in this electrophilic aromatic substitution. The silylium ion mediated formylation corresponds to Gattermann–Koch reactions promoted by strong Brønsted acids. The resulting silylcarboxonium ion of the arenecarbaldehyde was crystallographically characterized, for the first time revealing the molecular structure of this synthetically important intermediate.
From Metal–Organic Frameworks to Single‐Atom Fe Implanted N‐doped Porous Carbons: Efficient Oxygen Reduction in Both Alkaline and Acidic Media
Authors: Jiao Long , Wan Gang , Zhang Rui , Zhou Hua , Yu Shu‐Hong , Jiang Hai‐Long 
Published: May 2018

AbstractIt remains highly desired but a great challenge to achieve atomically dispersed metals in high loadings for efficient catalysis. Now porphyrinic metal–organic frameworks (MOFs) have been synthesized based on a novel mixed‐ligand strategy to afford high‐content (1.76 wt %) single‐atom (SA) iron‐implanted N‐doped porous carbon (FeSA‐N‐C) via pyrolysis. Thanks to the single‐atom Fe sites, hierarchical pores, oriented mesochannels and high conductivity, the optimized FeSA‐N‐C exhibits excellent oxygen reduction activity and stability, surpassing almost all non‐noble‐metal catalysts and state‐of‐the‐art Pt/C, in both alkaline and more challenging acidic media. More far‐reaching, this MOF‐based mixed‐ligand strategy opens a novel avenue to the precise fabrication of efficient single‐atom catalysts.
Catalytic Enantioselective Cloke–Wilson Rearrangement
Authors: Ortega Alesandere , Manzano Rubén , Uria Uxue , Carrillo Luisa , Reyes Efraim , Tejero Tomas , Merino Pedro , Vicario Jose L. 
Published: May 2018

AbstractRacemic cyclopropyl ketones undergo enantioselective rearrangement to deliver the corresponding dihydrofurans in the presence of a chiral phosphoric acid as the catalyst. The reaction involves activation of the donor‐acceptor cyclopropane substrate by the chiral Brønsted acid catalyst to promote the ring‐opening event, thus generating a carbocationic intermediate that subsequently undergoes cyclization. Computational studies and control experiments support this mechanistic pathway.
Synthesis, characterization and theoretical and fluorescence emission microscopy studies of new Pd/Pt–cyclopropa[60]fullerene complexes: Application of Taguchi method for optimization of parameters in Suzuki–Miyaura reaction
Authors: Sabounchei Seyyed Javad , Badpa Khadijeh , Hashemi Ali , Salehzadeh Sadegh , Maleki Farahnaz , Hosseinzadeh Leila 
Published: May 2018

The reactions of unsymmetric phosphorus ylides of the type [Ph2P(CH2)nPPh2C(H)C(O)C6H4‐p‐CN] (n = 1 (Y1); n = 2 (Y2)) with C60 and M(dba)2 (M = Pd or Pt; dba = dibenzylideneacetone) are reported. Based on the various coordination modes of these ylides in complexation, the following new Pd/Pt–cyclopropa[60]fullerene complexes were obtained: P,C‐coordinated [(η2‐C60)Pd(κ2‐Y1)] (1) and [(η2‐C60)Pt(κ2‐Y1)] (2) complexes and P‐coordinated [(η2‐C60)Pd(Y2)2] (3) and [(η2‐C60)Pt(Y2)2] (4) complexes. These compounds were characterized using Fourier transform infrared, UV–visible and NMR (1H, 13C and 31P) spectroscopies and scanning electron microscopy. Furthermore, cytotoxicity studies showed that nanoparticles of these complexes can be used as non‐toxic labels for cellular imaging application. Also energy decomposition analysis results revealed that the percentage contribution of ΔEelec in total interaction energy is considerably larger than that of ΔEorb. Thus, in all complexes the (η2‐C60)M(Y1) bond is considerably more electrostatic in nature than the (η2‐C60)M(Y1) bond. Finally, by application of the Taguchi method for optimization of parameters in Suzuki–Miyaura reaction, the catalytic activity of Pd complexes 1 and 3 was investigated in the cross‐coupling reaction of various aryl chlorides with phenylboronic acid. According to analysis of variance results, solvent has the highest F value and it has high contribution percentage (36.75%) to the yield of Suzuki–Miyaura reaction.
Prediction for regularized clusterwise multiblock regression
Authors: Bougeard S. , Cariou V. , Saporta G. , Niang N. 
Published: May 2018

AbstractIn a large variety of fields such as epidemiology, process monitoring, chemometrics, marketing, and social sciences among others, many research questions pertain to regression analysis from large data sets. Although in some cases standard regression will suffice, modeling is sometimes more challenging for various reasons (i) explain several variables; (ii) with a large number of explanatory variables organized into meaningful, usually ill‐conditioned, multidimensional matrices; (iii) where observations come from different subpopulations; and (iv) with the opportunity to predict new observations. Although some developed methods partially meet these challenges, none of them covers all these aspects. To fill this gap, a new method, called regularized clusterwise multiblock regression (CW.rMBREG), is proposed. The method CW.rMBREG combines clustering and a component‐based (multiblock) model associated with a well‐defined criterion to optimize. It provides simultaneously a partition of the observations into clusters along with the regression coefficients associated with each cluster. To go further, we propose to investigate a key feature generally neglected in clusterwise regression, ie, the prediction of new observations. The usefulness of CW.rMBREG is illustrated on the basis of both a simulation study and a real example in the field of indoor air quality. It results that CW.rMBREG improves the quality of the prediction and facilitates the interpretation of complex ill‐conditioned data. The proposed method is available for users through the R package mbclusterwise.
Synaptotagmin XIII expression and peritoneal metastasis in gastric cancer
Authors: Kanda M , Shimizu D , Tanaka H , Tanaka C , Kobayashi D , Hayashi M , Takami H , Niwa Y , Yamada S , Fujii T , Sugimoto H , Kodera Y 
Published: May 2018

Abstract

Background
Peritoneal metastasis is a frequent cause of death in patients with gastric cancer. The aim of this study was to identify molecules responsible for mediating peritoneal metastasis of gastric cancer.

Methods
Transcriptome and bioinformatics analyses were conducted to identify molecules associated with peritoneal metastasis. The therapeutic effects of intraperitoneally administered small interfering (si) RNA were evaluated using mouse xenograft models. Expression of mRNA and protein was determined in gastric tissues from patients with gastric cancer.

Results
Synaptotagmin XIII (SYT13) was expressed at significantly higher levels in patients with peritoneal recurrence, but not in those with hepatic or distant lymph node recurrence. Inhibition of SYT13 expression in a gastric cancer cell line transfected with SYT13-specific siRNA (siSYT13) was associated with decreased invasion and migration ability of the cells, but not with proliferation and apoptosis. Intraperitoneal administration of siSYT13 significantly inhibited the growth of peritoneal nodules and prolonged survival in mice. In an analysis of 200 patients with gastric cancer, SYT13 expression in primary gastric cancer tissues was significantly greater in patients with peritoneal recurrence or metastasis. A high level of SYT13 expression in primary gastric cancer tissues was an independent risk factor for peritoneal recurrence.

Conclusion
SYT13 expression in gastric cancer is associated with perioneal metatases and is a potential target for treatment.
Control of the Near Infrared Photoluminescence of Locally Functionalized Single‐Walled Carbon Nanotubes via Doping by Azacrown‐Ether Modification
Authors: Onitsuka Hisashi , Fujigaya Tsuyohiko , Nakashima Naotoshi , Shiraki Tomohiro 
Published: May 2018

AbstractDoped semiconducting single‐walled carbon nanotubes (SWNTs) through local chemical functionalization (lf‐SWNTs) show fascinating photoluminescence (PL) that appears with a longer wavelength and enhanced quantum yield compared to the original PL of non‐modified SWNTs. In this study, we introduce an azacrown ether moiety at the doped sites of lf‐SWNTs (CR‐lf‐SWNTs), and observe selective PL wavelength shifts depending on different interaction modes of silver ion inclusion and protonation of the amino group in the ring. Interestingly, their different values of the wavelength shifts show a clear correlation with calculated electron density of the nitrogen atom in the azacrown moiety in case of the inclusion form and the protonated form. This newly‐observed responsiveness based on molecular interactions is expected to create doped sites that can versatilely control the PL functions based on molecular systems.
An Engineered Lithocholate‐Based Facial Amphiphile Stabilizes Membrane Proteins: Assessing the Impact of Detergent Customizability on Protein Stability
Authors: Das Manabendra , Du Yang , Mortensen Jonas S. , Bae Hyoung Eun , Byrne Bernadette , Loland Claus J. , Kobilka Brian K. , Chae Pil Seok 
Published: May 2018

AbstractAmphiphiles are critical tools for the structural and functional study of membrane proteins. Membrane proteins encapsulated by conventional head‐to‐tail detergents tend to undergo structural degradation, necessitating the development of structurally novel agents with improved efficacy. In recent years, facial amphiphiles have yielded encouraging results in terms of membrane protein stability. Herein, we report a new facial detergent (i.e., LFA‐C4) that confers greater stability to tested membrane proteins than the bola form analogue. Owing to the increased facial property and the adaptability of the detergent micelles in complex with different membrane proteins, LFA‐C4 yields increased stability compared to n‐dodecyl‐β‐d‐maltoside (DDM). Thus, this study not only describes a novel maltoside detergent with enhanced protein‐stabilizing properties, but also shows that the customizable nature of a detergent plays an important role in the stabilization of membrane proteins. Owing to both synthetic convenience and enhanced stabilization efficacy for a range of membrane proteins, the new agent has major potential in membrane protein research.
Rational Design and Synthesis of Modified Teixobactin Analogues: In Vitro Antibacterial Activity against Staphylococcus aureus, Propionibacterium acnes and Pseudomonas aeruginosa
Authors: Ng Vivian , Kuehne Sarah A. , Chan Weng C. 
Published: May 2018

AbstractTeixobactin, a recently discovered depsipeptide that binds to bacterial lipid II and lipid III, provides a promising molecular scaffold for the design of new antimicrobials. Herein, we describe the synthesis and antimicrobial evaluation of systematically modified teixobactin analogues. The replacement of the Ile11 residue with aliphatic isosteres, the modification of the guanidino group at residue 10 and the introduction of a rigidifying residue, that is, dehydroamino acid, into the macrocyclic ring generated useful structure–activity information. Extensive antimicrobial susceptibility assessment against a panel of clinically relevant Staphylococcus aureus and Propionibacterium acnes strains led to the identification of the new lead compound, [Arg(Me)10,Nle11]teixobactin, with an excellent bactericidal activity (minimum inhibitory concentration (MIC)=2–4 μg mL−1). Significantly, the antimicrobial activity of several of the teixobactin analogues against the pathogenic Gram‐negative Pseudomonas aeruginosa was “restored” when combined with the sub‐MIC concentration of the outer membrane‐disruptive antibiotic colistin. The antimicrobial effectiveness of a [Tfn10,Nle11]teixobactin (32 μg mL−1)–colistin (2 μg mL−1; 0.5×MIC) combination against P. aeruginosa PAO1 reveals, for the first time, an alternative therapeutic option in the treatment of Gram‐negative infections.
Multivalent Metallosupramolecular Assemblies as Effective DNA Binding Agents
Authors: Drożdż Wojciech , Walczak Anna , Bessin Yannick , Gervais Virginie , Cao Xiao‐Yu , Lehn Jean‐Marie , Ulrich Sébastien , Stefankiewicz Artur R. 
Published: May 2018

AbstractWe report the implementation of coordination chemistry onto the generation of new types of metallosupramolecular complexes with laterally appended cationic moieties for DNA binding in buffered aqueous media. Utilization of an N,N,O‐type coordination pocket along with an octahedral zinc(II) metal ion allowed us to obtain mono‐ and tetranuclear complexes in both solution and solid state, as confirmed by NMR spectroscopy and single‐crystal X‐ray diffraction, respectively. By using isothermal titration calorimetry and gel electrophoresis, multiply charged cationic assemblies were observed to effectively bind to DNA through multivalent electrostatic interactions. Furthermore, we observed a correlation between the multivalency of the compounds employed and the effectiveness of DNA binding.
Benzofuran and Indole: Promising Scaffolds for Drug Development in Alzheimer's Disease
Authors: Goyal Deepti , Kaur Amandeep , Goyal Bhupesh 
Published: May 2018

AbstractAlzheimer's disease (AD) is a progressive neurodegenerative disease with no clinically accepted treatment to cure or halt its progression. The Food and Drug Administration has approved drugs (e.g., rivastigmine, donepezil, galantamine, and memantine) that at best provide marginal benefits, thus emphasizing the urgent need to explore other molecular entities as future drug candidates for AD. Looking at the wide pharmaceutical applications of heterocyclic compounds and particularly those containing benzofuran and indole ring systems, these molecular frameworks have drawn special attention from medicinal chemists for further evaluation in numerous diseases. This article focuses on the history and recent advances of benzofuran‐ and indole‐based compounds as inhibitors of butyrylcholinesterase, acetylcholinesterase, γ‐secretase, β‐secretase, tau misfolding, and β‐amyloid aggregation.
Timing of palliative care needs reporting and aggressiveness of care near the end of life in metastatic lung cancer: A national registry‐based study
Authors: Goldwasser François , Vinant Pascale , Aubry Régis , Rochigneux Philippe , Beaussant Yvan , Huillard Olivier , Morin Lucas 
Published: May 2018

BACKGROUNDEarly integration of palliative care for patients with metastatic lung cancer improves their quality of life and survival and reduces the aggressiveness of care near the end of life. This study examined the association between the timing of palliative care needs reporting and the aggressiveness of end‐of‐life care.METHODSThis retrospective cohort study used the French National Hospital Registry to identify all hospitalized adults (≥20 years old) who died of metastatic lung cancer in France between 2010 and 2013. It compared the use of care and treatments near the end of life as a function of the timing of the first reporting of palliative care needs. The use of chemotherapy and the use of invasive ventilation were defined as primary outcomes. Propensity score weighting was used to control for potential confounders.RESULTSAmong a total of 64,950 deceased patients with metastatic lung cancer, the reporting of palliative care needs was characterized as timely (from 91 to 31 days before death) for 26.3%, late (from 30 to 8 days before death) for 31.5%, and very late (from 7 to 0 days before death) for 12.8%. Palliative care needs were not reported for 19,106 patients (29.4%). Patients with timely reporting of palliative care needs had the earliest and most progressive decrease in the use of anticancer therapy. The use of invasive ventilation also increased with a delay in palliative care needs reporting.CONCLUSIONSThere is a clear association between the timing of palliative care needs reporting and the aggressiveness of care near the end of life. Cancer 2018;124:3044‐51. © 2018 American Cancer Society.
Associations among human papillomavirus, inflammation, and fatigue in patients with head and neck cancer
Authors: Xiao Canhua , Beitler Jonathan J. , Higgins Kristin A. , Glazer Toby , Huynh Linh Kha , Paul Sudeshna , Felger Jennifer C. , Wommack Evanthia C. , Saba Nabil F. , Shin Dong M. , Bruner Deborah W. , Miller Andrew H. 
Published: May 2018

BACKGROUNDHuman papillomavirus (HPV) infection has contributed to an increased incidence of squamous cell carcinoma of the head and neck (SCCHN). Fatigue is a major side effect of SCCHN and its treatment. However, to the authors' knowledge, the association between HPV and fatigue has not been examined to date, nor is it known whether HPV influences biological mechanisms of fatigue, including inflammation.METHODSPatients with SCCHN who were without distant metastasis were assessed at baseline (pre‐radiotherapy) and 1 month and 3 months postradiotherapy. Fatigue was measured using the Multidimensional Fatigue Inventory. Peripheral inflammation was assessed by plasma C‐reactive protein (CRP), interleukin 1 receptor antagonist (IL‐1ra), soluble tumor necrosis factor receptor 2 (sTNFR2), and IL‐6. Mixed effect models were used to examine associations.RESULTSA total of 94 patients who were newly diagnosed were enrolled; 53% had HPV‐related tumors. Patients with HPV‐unrelated tumors had higher fatigue and higher plasma CRP, sTNFR2, and IL‐6 over time, especially at baseline and 3 months after intensity‐modulated radiotherapy compared with those with HPV‐related tumors (allP < .05). However, fatigue and plasma sTNFR2 increased more significantly from baseline to 1 month after radiotherapy in the HPV‐related group compared with the HPV‐unrelated group (bothP < .01). Controlling for significant covariates, HPV status and inflammation were found to be independent predictors of fatigue over time.CONCLUSIONSHPV status is an important marker of vulnerability to the behavioral and immune consequences of SCCHN and its treatment, providing support for different symptom management strategies. Special emphasis should be placed on addressing marked persistent fatigue in patients with HPV‐unrelated tumors, whereas attention should be paid to the large increases in fatigue during treatment among patients with HPV‐related tumors.Cancer2018.©2018 American Cancer Society.
Endo or Exo? Structures of Gas‐Phase Alkali Metal Cation/Aromatic Half‐Belt Complexes
Authors: Chen Yanyang , Jami‐Alahmadi Yasaman , Unikela Kiran Sagar , Bodwell Graham J. , Fridgen Travis D. 
Published: May 2018

Abstract1,1,9,9‐Tetramethyl[9](2,11)teropyrenophane (TM9TP), a belt‐shaped molecule, has a sizable cavity that molecules or ions could occupy. In this study, the question of whether TM9TP forms gas‐phase ion‐molecule complexes with metal cations (K+, Rb+, Cs+) situated inside or outside the TM9TP cavity was addressed using both experimental and computational methods. Complexes were trapped in a Fourier transform ion cyclotron resonance mass spectrometer and their structures were explored by some novel physical chemistry/mass spectrometry methods. Blackbody infrared radiative dissociation kinetics reveal two populations of ions, a fast dissociating fraction and a persistent fraction. Infrared multiphoton dissociation spectra (vibrational spectra) provide very strong evidence that the most abundant population is a complex where the metal cation is inside the TM9TP cavity, endo‐TM9TP. Red‐shifted C−H stretching bands present in the gas‐phase vibrational spectra of these ionic complexes show that there is an interaction between the metal cation and bridge C−H bonds due to the cation sitting inside the cavity of TM9TP. B3LYP/6‐31+G(d,p) calculations showed the endo complexes to be the lowest in energy; about 60 kJ mol−1 more thermodynamically stable and more than 120 kJ mol−1 kinetically more stable than the exo complex.