bluuebunny/crossref_metadata_2025_split huggingface dataset:
Asymmetric Total Synthesis of Mycoleptodiscin A
Authors: Zhou Shupeng , Chen Hao , Luo Yijie , Zhang Wenhao , Li Ang 
Published: April 2015

AbstractThe first total synthesis of mycoleptodiscin A, a structurally unusual indolosesquiterpenoid possessing an ortho‐benzoquinone motif, has been accomplished. A sulfone alkylation coupled two readily available fragments to give an aryl triene intermediate. The tetracyclic core of the molecule was assembled through a highly enantioselective iridium‐catalyzed polyene cyclization. The benzylic homologation was achieved by a cationic cyanation. The indole motif was constructed via a copper‐mediated intramolecular CN bond formation at a late stage.
Revisiting the Solution Structure of Ceric Ammonium Nitrate
Authors: Demars Thomas J. , Bera Mrinal K. , Seifert Soenke , Antonio Mark R. , Ellis Ross J. 
Published: April 2015

AbstractCeric ammonium nitrate (CAN) is a single‐electron‐transfer reagent with unparalleled utility in organic synthesis, and has emerged as a vital feedstock in diverse chemical industries. Most applications use CAN in solution where it is assigned a monomeric [CeIV(NO3)6]2− structure; an assumption traced to half‐century old studies. Using synchrotron X‐rays and Raman spectroscopy we challenge this tradition, converging instead on an oxo‐bridged dinuclear complex, even in strong nitric acid. Thus, one equivalent of CAN is recast as a two‐electron‐transfer reagent and a redox‐activated superbase, raising questions regarding the origins of its reactivity with organic molecules and giving new fundamental insight into the stability of polynuclear complexes of tetravalent ions.
Isomerization of Olefins Triggered by Rhodium‐Catalyzed CH Bond Activation: Control of Endocyclic β‐Hydrogen Elimination
Authors: Yip Stephanie Y. Y. , Aïssa Christophe 
Published: April 2015

AbstractFive‐membered metallacycles are typically reluctant to undergo endocyclic β‐hydrogen elimination. The rhodium‐catalyzed isomerization of 4‐pentenals into 3‐pentenals occurs through this elementary step and cleavage of two CH bonds, as supported by deuterium‐labeling studies. The reaction proceeds without decarbonylation, leads to trans olefins exclusively, and tolerates other olefins normally prone to isomerization. Endocyclic β‐hydrogen elimination can also be controlled in an enantiodivergent reaction on a racemic mixture.
Cloning, expression, and characterization of a thermostablel‐arginase fromGeobacillus thermodenitrificansNG80‐2 forl‐ornithine production
Authors: Huang Kai , Mu Wanmeng , Zhang Tao , Jiang Bo , Miao Ming 
Published: April 2015

AbstractArginase (l‐arginine amidinohydrolase, EC 3.5.3.1) can efficiently catalyze conversion of arginine to ornithine. Therefore, this enzyme can be used to producel‐ornithine froml‐arginine. In this article, thel‐arginase gene encoding theGeobacillus thermodenitrificansNG80‐2 was cloned and overexpressed inEscherichia coli. The specific activity of the purified enzyme was 138.3 U/mg. The molecular mass of thel‐arginase was approximately 33.0 kDa as estimated by SDS‐PAGE and 192.0 kDa as determined by gel‐filtration chromatography. Manganese ions were the optimum metal cofactor for activity, whereas the enzyme was slightly inhibited by Mg2+, Cu2+, Ba2+, Ca2+, and Zn2+. Activity was optimal at pH 9.0 and 80 °C, and the protein was stable at 40 and 50 °C. The recombinant enzyme was a uricotelic arginase. Using arginine as the substrate, the Michaelis–Menten constant (Km) and catalytic efficiency (kcat/Km) were measured to be 171.9 mM and 3.8 mM−1 s−1, respectively. Trp and His residues were directly involved in thel‐arginase activity evaluated by inactivation agents. The biosynthesis yield ofl‐ornithine by the purified enzyme was 36.9 g/L, and the molar yield was 97.2%.
Titanium dioxide nanoparticles provide protection against polycyclic aromatic hydrocarbon BaP and chrysene‐induced perturbation of DNA repair machinery: A computational biology approach
Authors: Dhasmana Anupam , Jamal Qazi Mohd. Sajid , Gupta Richa , Siddiqui Mohd. Haris , Kesari Kavindra Kumar , Wadhwa Gulshan , khan Saif , Haque Shafiul , Lohani Mohtashim 
Published: April 2015

AbstractWe examined the interaction of polycyclic hydrocarbons (PAHs) like benzo‐α‐pyrene (BaP), chrysene, and their metabolites 7,8‐dihydro‐7,8‐dihydroxybenzo(a)pyrene,9,10‐oxide (BPDE) and chrysene 1,2‐diol‐3,4‐epoxide‐2 (CDE), with the enzymes involved in DNA repair. We investigated interaction of 120 enzymes with PAHs and screened out 40 probable targets among DNA repair enzymes, on the basis of higher binding energy than positive control. Out of which, 20 enzymes lose their function in the presence of BaP, chrysene, and their metabolites, which may fetter DNA repair pathways resulting in damage accumulation and finally leading to cancer formation. We propose the use of nanoparticles as a guardian against the PAH's induced toxicity. PAHs enter the cell via aryl hydrocarbon receptor (AHR). TiO2 NP showed a much higher docking score with AHR (12,074) as compared with BaP and chrysene with AHR (4,600 and 4,186, respectively), indicating a preferential binding of TiO2 NP with the AHR. Further, docking of BaP and chrysene with the TiO2 NP bound AHR complex revealed their strong adsorption on TiO2 NP itself, and not on their original binding site (at AHR). TiO2 NPs thereby prevent the entry of PAHs into the cell via AHR and hence protect cells against the deleterious effects induced by PAHs.
Induction of NRF2‐mediated gene expression by dietary phytochemical flavones apigenin and luteolin
Authors: Paredes‐Gonzalez Ximena , Fuentes Francisco , Jeffery Sundrina , Saw Constance Lay‐Lay , Shu Limin , Su Zheng‐Yuan , Kong Ah‐Ng Tony 
Published: April 2015

AbstractApigenin (API) and luteolin (LUT) have been used as therapeutic agents in folk medicine for thousands of years. These compounds exert a variety of biological activities, including anticancer, antioxidant and antiinflammatory activities. This study investigated whether API and LUT could activate Nrf2‐antioxidant response element (ARE)‐mediated gene expression and induce antiinflammatory activities in human hepatoma HepG2 cells. The compounds did not exhibit any substantial toxicity at low doses (1.56–6.25 µm). The induction of ARE activity was assessed in HepG2‐C8 cells after treatment with low doses of API and LUT for 6 and 12 h. It was found that the induction of ARE activity by these compounds at the higher doses was comparable to the effects of the positive control, SFN at a dose of 6.25 µm. Exposure to the PI3K inhibitor LY294002 abolished ARE activation by both API and LUT, whereas the ERK‐1/2 inhibitor PD98059 only decreased ARE activity induced by API. Both compounds significantly increased the endogenous mRNA and protein levels of Nrf2 and Nrf2 target genes with important effects on heme oxygenase‐1 (HO‐1) expression. API and LUT significantly and dose‐dependently decreased the production of nitric oxide (NO), nitric oxide synthase (iNOS) and cytosolic phospholipase A2 (cPLA2), which were induced by the treatment of HepG2 cells with 1 µg/ml of lipopolysaccharide (LPS) for 24 h. The results indicate that API and LUT significantly activate the PI3K/Nrf2/ARE system, and this activation may be responsible for their antiinflammatory effects, as demonstrated by the suppression of LPS‐induced NO, iNOS and cPLA2. Copyright © 2015 John Wiley & Sons, Ltd.
Biomechanical effects of the transcondylar approach on the craniovertebral junction
Authors: Cardoso Alberto C. , Fontes Ricardo B.V. , Tan Lee A. , Rhoton Albert L. , Roh Sung W. , Fessler Richard G. 
Published: April 2015

The transcondylar variation of the far‐lateral, retrosigmoid approach is intended for pathologies in the anterolateral portion of the foramen magnum. That area is more clearly visualized when a fraction of the ipsilateral occipital condyle is removed. In this study, the biomechanical effect of this approach on occiput‐C2 rotation was investigated. Our hypothesis was that the biomechanical characteristics are significantly altered following the transcondylar approach. Five human cadaveric upper cervical spine specimens (occiput‐C7) were used in the study. Torsional moments were applied from zero to a maximum of 1.5 N m to the left and to the right using a mechanical testing machine. The resulting rotational motions of the O–C1, C1–2, and O–C2 segments were measured in the intact specimen and after a simulated right‐sided transcondylar approach with resection of 2/3 of the condyle, confirmed by CT scanning and visual inspection. After the posterior two‐thirds of the occipital condyle were removed, the neutral zone (NZ) increased 1.3° to the left and 2° to the right at C0–C1, and 7.4° to the left and 6.2° to the right at C1–2. The cumulative increase in NZ between O and C2 was 8.7° to the left and 8.2° to the right. The transcondylar approach also resulted in significant increases in range of motion (ROM) in axial rotation to both sides in all segments. ROM increased 2.8° to the left and 2.4° to the right between C0 and C1, 7.3° to the left and 5.4° to the right between C1 and C2, and 10.1° to the left and 7.8° to the right between CO and C2. Upon inspection, the area of the occipital condyle where the alar ligament attaches had been completely removed in three of the five specimens. Removing the posteromedial two‐thirds of one occipital condyle alters the normal axial rotational movements of the craniovertebral junction on both sides. The insertion of the alar ligament can be inadvertently removed during condylar resection, and this could contribute to atlanto‐axial instability. There is a biomechanical substrate to cranio‐cervical instability following a transcondylar approach; these patients may need to be followed over several years to ensure it does not progress and necessitate occipito‐cervical fusion. Clin. Anat. 28:683–689, 2015. © 2015 Wiley Periodicals, Inc.
Functional Characterization of Different ORFs Including Luciferase‐Like Monooxygenase Genes from the Mensacarcin Gene Cluster
Authors: Maier Sarah , Heitzler Tanja , Asmus Katharina , Brötz Elke , Hardter Uwe , Hesselbach Katharina , Paululat Thomas , Bechthold Andreas 
Published: April 2015

AbstractThe biologically active compound mensacarcin is produced by Streptomyces bottropensis. The cosmid cos2 contains a large part of the mensacarcin biosynthesis gene cluster. Heterologous expression of this cosmid in Streptomyces albus J1074 led to the production of the intermediate didesmethylmensacarcin (DDMM). In order to gain more insights into the biosynthesis, gene inactivation experiments were carried out by λ‐Red/ET‐mediated recombination, and the deletion mutants were introduced into the host S. albus. In total, 23 genes were inactivated. Analysis of the metabolic profiles of the mutant strains showed the complete collapse of DDMM biosynthesis, but upon overexpression of the SARP regulatory gene msnR1 in each mutant new intermediates were detected. The compounds were isolated, and their structures were elucidated. Based on the results the specific functions of several enzymes were determined, and a pathway for mensacarcin biosynthesis is proposed.
Mechanism of Thyroxine Deiodination by Naphthyl‐Based Iodothyronine Deiodinase Mimics and the Halogen Bonding Role: A DFT Investigation
Authors: Fortino Mariagrazia , Marino Tiziana , Russo Nino , Sicilia Emilia 
Published: April 2015

AbstractThis paper deals with a systematic density functional theory (DFT) study aiming to unravel the mechanism of the thyroxine (T4) conversion into 3,3′,5‐triiodothyronine (rT3) by using different bio‐inspired naphthyl‐based models, which are able to reproduce the catalytic functions of the type‐3 deiodinase ID‐3. Such naphthalenes, having two selenols, two thiols, and a selenol–thiol pair in peri positions, which were previously synthesized and tested in their deiodinase activity, are able to remove iodine selectively from the inner ring of T4 to produce rT3. Calculations were performed including also an imidazole ring that, mimicking the role of the His residue, plays an essential role deprotonating the selenol/thiol moiety. For all the used complexes, the calculated potential energy surfaces show that the reaction proceeds via an intermediate, characterized by the presence of a XIC (X=Se, S) halogen bond, whose transformation into a subsequent intermediate in which the CI bond is definitively cleaved and the incipient XI bond is formed represents the rate‐determining step of the whole process. The calculated trend in the barrier heights of the corresponding transition states allows us to rationalize the experimentally observed superior deiodinase activity of the naphthyl‐based compound with two selenol groups. The role of the peri interactions between chalcogen atoms appears to be less prominent in determining the deiodination activity.
Palladium/Zinc Co‐Catalyzed syn‐Stereoselectively Asymmetric Ring‐Opening Reaction of Oxabenzonorbornadienes with Phenols
Authors: Li Sifeng , Xu Jianbin , Fan Baomin , Lu Zhiwu , Zeng Chaoyuan , Bian Zhaoxiang , Zhou Yongyun , Wang Jun 
Published: April 2015

AbstractA new palladium/zinc co‐catalyst system associated with chiral (R)‐Difluorphos for asymmetric ring‐opening reaction of oxabenzonorbornadienes with phenols is reported. This catalyst system allows the formation of cis‐2‐aryloxy‐1,2‐dihydronaphthalen‐1‐ol products in good yields (up to 95 % yield) with excellent enantioselectivities (up to 99 % ee). The cis‐configuration of the product has been confirmed by X‐ray crystal structure analysis. To the best of our knowledge, it represents the first example in ring‐opening reactions of bicycloalkenes with heteronucleophiles in a syn‐stereoselective manner.
Template‐Dependent Photochemical Reactivity of Molecular Metal Oxides
Authors: Tucher Johannes , Peuntinger Katrin , Margraf Johannes T. , Clark Timothy , Guldi Dirk M. , Streb Carsten 
Published: April 2015

AbstractA combined experimental and theoretical study shows that the photooxidative activity of two isostructural metal oxide clusters depends on their internal templates. To this end, two halide‐templated bismuth vanadium oxide clusters [X(Bi(dmso)3)2V12O33]− (X=Cl−, Br−) are reported and fully characterized. The two clusters show similar absorption features and illustrate that bismuth incorporation results in increased visible‐light absorption. Significantly higher photooxidative activity is observed for the bromide‐templated cluster compared with the chloride‐templated one. Detailed photophysical assays and complementary DFT calculations suggest that the more efficient triplet excited state formation in the Br−‐containing cluster is the decisive step in the photocatalysis and is due to the heavy‐atom effect of the bromide. This concept can therefore open new pathways towards the optimization of photocatalytic activity in metal oxide clusters.
Patterns of change in cognitive function with anastrozole therapy
Authors: Bender Catherine M. , Merriman John D. , Gentry Amanda L. , Ahrendt Gretchen M. , Berga Sarah L. , Brufsky Adam M. , Casillo Frances E. , Dailey Meredith M. , Erickson Kirk I. , Kratofil Frances M. , McAuliffe Priscilla F. , Rosenzweig Margaret Q. , Ryan Christopher M. , Sereika Susan M. 
Published: April 2015

BACKGROUNDThe purpose of this study was to examine and compare the effects of the first 18 months of anastrozole therapy on cognitive function in women with breast cancer.METHODSThis large, longitudinal cohort study was composed of postmenopausal women with early‐stage breast cancer who received chemotherapy plus anastrozole (n = 114) or anastrozole alone (n = 173) and a control group (n = 110). Cognitive function was assessed before systemic therapy and 6, 12, and 18 months after therapy initiation and at comparable time points in controls.RESULTSThe chemotherapy‐anastrozole and anastrozole‐alone groups had poorer executive function than the controls at nearly all time points (P < .0001 to P = .09). A pattern of deterioration in working memory and concentration was observed during the first 6 months of anastrozole therapy for the chemotherapy‐anastrozole group (P < .0001 and P < .0009, respectively) and the anastrozole‐alone group (P = .0008 and P = .0002, respectively). This was followed by improved working memory and concentration from 6 to 12 months in both groups. The anastrozole‐alone group had a second decline in working memory and concentration from 12 to 18 months after the initiation of therapy (P < .0001 and P = .02, respectively).CONCLUSIONSWomen with breast cancer had poorer executive functioning from the period before therapy through the entire first 18 months of therapy. A pattern of decline in working memory and concentration with initial exposure to anastrozole was observed. Women receiving anastrozole alone had a second deterioration in working memory and concentration from 12 to 18 months after therapy initiation. The longer term effects (>18 months) of anastrozole on cognitive function remain to be determined. Cancer 2015;121:2627–2636. © 2015 American Cancer Society.
Paths to health equity: Local area variation in progress toward eliminating breast cancer mortality disparities, 1990‐2009
Authors: Rust George , Zhang Shun , Malhotra Khusdeep , Reese Leroy , McRoy Luceta , Baltrus Peter , Caplan Lee , Levine Robert S. 
Published: April 2015

BACKGROUNDUS breast cancer deaths have been declining since 1989, but African American women are still more likely than white women to die of breast cancer. Black/white disparities in breast cancer mortality rate ratios have actually been increasing.METHODSAcross 762 US counties with enough deaths to generate reliable rates, county‐level, age‐adjusted breast cancer mortality rates were examined for women who were 35 to 74 years old during the period of 1989‐2010. Twenty‐two years of mortality data generated twenty 3‐year rolling average data points, each centered on a specific year from 1990 to 2009. Mixed linear models were used to group each county into 1 of 4 mutually exclusive trend patterns. The most recent 3‐year average black breast cancer mortality rate for each county was also categorized as being worse or not worse than the breast cancer mortality rate for the total US population.RESULTSMore than half of the counties (54%) showed persistent, unchanging disparities. Roughly 1 in 4 (24%) had a divergent pattern of worsening black/white disparities. However, 10.5% of the counties sustained racial equality over the 20‐year period, and 11.7% of the counties actually showed a converging pattern from high disparities to greater equality. Twenty‐three counties had 2008‐2010 black mortality rates better than the US average mortality rate.CONCLUSIONSDisparities are not inevitable. Four US counties have sustained both optimal and equitable black outcomes as measured by both absolute (better than the US average) and relative benchmarks (equality in the local black/white rate ratio) for decades, and 6 counties have shown a path from disparities to health equity. Cancer 2015;121:2765‐2774. © 2015 American Cancer Society
Carbazole‐Based Molecular Glasses as Hole‐Transporting Materials in Solid State Dye‐Sensitized Solar Cells
Authors: Bui Thanh‐Tuân , Shah Said Karim , Abbas Mamatimin , Sallenave Xavier , Sini Gjergji , Hirsch Lionel , Goubard Fabrice 
Published: April 2015

AbstractThree 3,6‐di(4‐methoxyphenyl)amino N‐alkylated carbazoles were synthesized, characterized and incorporated in solid state dye‐sensitized solar cells. Devices using these compounds as solid hole conductors showed relative high Voc thanks to good energy level matching between them and D102 dye. However, they yield relatively low Jsc and FF compared to spiro‐OMeTAD‐based control devices, which is due to an order of magnitude lower mobility and conductivity with respect to spiro‐OMeTAD. Maximum PCEs for N‐ethyl and N‐hexyl 3,6‐di(4‐methoxyphenyl)amino carbazoles (2 a, 2 b) are 1.6 %, and 1.8 % respectively, whereas spiro‐OMeTAD devices gave 4.4 %. Stability tests in air under continuous illumination have been reported.
Photocatalytic Activity of Au/TiO2 Photocatalysts for H2 Evolution: Role of the Au Nanoparticles as a Function of the Irradiation Wavelength
Authors: Serra Marco , Albero Josep , García Hermenegildo 
Published: April 2015

AbstractAn investigation of hydrogen production with a series of Au/TiO2 photocatalysts reveals that the Au nanoparticles play different roles depending on the wavelength of the light irradiation. Under visible‐light irradiation, the photoactivity is primarily controlled by the intensity of the Au surface plasmon band, whereas under UV irradiation the Au nanoparticles act as co‐catalysts with TiO2.
Immobilization of Distinctly Capped CdTe Quantum Dots onto Porous Aminated Solid Supports
Authors: Rodrigues S. Sofia M. , Ribeiro David S. M. , Frigerio Christian , Costa Susana P. F. , Prior João A. V. , Pinto Paula C. A. G. , Santos João L. M. , Saraiva M. Lúcia M. F. S. , Passos Marieta L. C. 
Published: April 2015

AbstractImmobilization of quantum dots (QDs) onto solid supports could improve their applicability in the development of sensing platforms and solid‐phase reactors by allowing the implementation of reusable surfaces and the execution of repetitive procedures. As the reactivity of QDs relies mostly on their surface chemistry, immobilization could also limit the disruption of solution stability that could prevent stable measurements. Herein, distinct strategies to immobilize QDs onto porous aminated supports, such as physical adsorption and the establishment of chemical linking, were evaluated. This work explores the influence of QD capping and size, concentration, pH, and contact time between the support and the QDs. Maximum QD retention was obtained for physical adsorption assays. Freundlich and Langmuir isotherms were used to analyze the equilibrium data. Gibbs free energy, enthalpy, and entropy were calculated and the stability of immobilized QDs was confirmed.
Intramolecular Hydrogen Bonds Enhance Disparity in Reactivity between Isomers of Photoswitchable Sorbents and CO2: A Computational Study
Authors: Tang Huarong , Lu Dongmei , Wu Chao 
Published: April 2015

AbstractReducing the emission of greenhouse gases, such as CO2, requires efficient and reusable capture materials. The energy for regenerating sorbents is critical to the cost of CO2 capture. Here, we design a series of photoswitchable CO2 capture molecules by grafting Lewis bases, which can covalently bond CO2, to azo‐based backbones that can switch configurations upon light stimulation. The first‐principles calculations demonstrate that intramolecular hydrogen bonds are crucial for enlarging the difference of CO2 binding strengths to the cis and trans isomers. As a result, the CO2–sorbent interaction can be light‐adjusted from strong chemical bonding in one configuration to weak bonding in the other, which may lead to a great energy reduction in sorbent regeneration.