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排序方式: 共有1222条查询结果,搜索用时 15 毫秒
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Guillermo?Martínez-Flórez Heleno?Bolfarine Héctor?W.?GómezEmail author 《Methodology and Computing in Applied Probability》2017,19(3):913-933
In this paper the sinh-power model is developed as a natural follow up to the log-linear Birnbaum-Saunders power model. The class of models resulting, incorporates the sinh-power-normal model, the ordinary sinh-normal model and the log-linear Birnbaum-Saunders model (Rieck and Nedelman, Technometrics 33:51–60, 1991). Maximum likelihood estimation is developed with the Hessian matrix used for standard error estimation. An application is reported for the data set on lung cancer studied in Kalbfleisch and Prentice (2002), where it is shown that the log-linear Birnbaum-Saunders power-normal model presents better fit than the log-linear Birnbaum-Saunders model. Another application is devoted to a fatigue data set previously analyzed in the literature. A nonlinear Birnbaum-Saunders power-normal model is fitted to the data set, with satisfactory performance. 相似文献
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Jorge Labella Dr. Gonzalo Durán-Sampedro Swathi Krishna Prof. M. Victoria Martínez-Díaz Prof. Dirk M. Guldi Prof. Tomás Torres 《Angewandte Chemie (International ed. in English)》2023,62(5):e202214543
Large π-conjugated systems are key in the area of molecular materials. Herein, we prepare via AuI-catalyzed cyclization a series of fully π-conjugated anthracene-fused oligo-BODIPYs. Their structural and optoelectronic properties were studied by several techniques, ranging from X-ray, UV/Vis, and cyclic voltammetry to transient absorption spectroscopy. As a complement, their electronic structures were explored by means of Density Functional Theory (DFT) calculations. Depending on the size and shape of the π-conjugated skeleton, unique features—such as face-to-face supramolecular organization, NIR absorption and fluorescence as well as strong electron accepting character—were noted. All in all, the aforementioned features render them valuable for technological applications. 相似文献
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ATP-Independent and Cell-Free Biosynthesis of β-Hydroxy Acids Using Vinyl Esters as Smart Substrates
Dr. Alejandro H. Orrego Dr. Maria Grazia Rubanu Idania L. López Daniel Andrés-Sanz Dr. Guillermo García-Marquina Dr. German E. Pieslinger Prof. Luca Salassa Prof. Fernando López-Gallego 《Angewandte Chemie (International ed. in English)》2023,62(13):e202218312
In vitro biosynthetic pathways that condense and reduce molecules through coenzyme A (CoASH) activation demand energy and redox power in the form of ATP and NAD(P)H, respectively. These coenzymes must be orthogonally recycled by ancillary reactions that consume chemicals, electricity, or light, impacting the atom economy and/or the energy consumption of the biosystem. In this work, we have exploited vinyl esters as dual acyl and electron donor substrates to synthesize β-hydroxy acids through a non-decarboxylating Claisen condensation, reduction and hydrolysis stepwise cascade, including a NADH recycling step, catalyzed by a total of 4 enzymes. Herein, the chemical energy to activate the acyl group with CoASH and the redox power for the reduction are embedded into the vinyl esters. Upon optimization, this self-sustaining cascade reached a titer of (S)-3-hydroxy butyrate of 24 mM without requiring ATP and simultaneously recycling CoASH and NADH. This work illustrates the potential of in vitro biocatalysis to transform simple molecules into multi-functional ones. 相似文献
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Zhongxin Chen Glenn Quek Ji-Yu Zhu Samuel J. W. Chan Sarah J. Cox-Vázquez Fernando Lopez-Garcia Prof. Guillermo C. Bazan 《Angewandte Chemie (International ed. in English)》2023,62(37):e202307101
We report a rationally designed membrane-intercalating conjugated oligoelectrolyte (COE), namely COE-IC , which endows aerobic N2-fixing bacteria Azotobacter vinelandii with a light-harvesting ability that enables photosynthetic ammonia production. COE-IC possesses an acceptor-donor-acceptor (A-D-A) type conjugated core, which promotes visible light absorption with a high molar extinction coefficient. Furthermore, COE-IC spontaneously associates with A. vinelandii to form a biohybrid in which the COE is intercalated within the lipid bilayer membrane. In the presence of L-ascorbate as a sacrificial electron donor, the resulting COE-IC /A. vinelandii biohybrid showed a 2.4-fold increase in light-driven ammonia production, as compared to the control. Photoinduced enhancement of bacterial biomass and production of L-amino acids is also observed. Introduction of isotopically enriched 15N2 atmosphere led to the enrichment of 15N-containing intracellular metabolites, consistent with the products being generated from atmospheric N2. 相似文献
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Vijayakumar Sekar González-Sánchez Zaira I. Malaikozhundan Balasubramanian Saravanakumar Kandasamy Divya Mani Vaseeharan Baskaralingam Durán-Lara Esteban F. Wang Myeong-Hyeon 《Journal of Cluster Science》2021,32(5):1129-1139
Journal of Cluster Science - Metal oxide nanoparticles (NPs) have gained attention in biomedicine due to their broad spectrum of applications, such as targeted drug delivery, their use as... 相似文献
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Norma Ruiz-Torres Antonio Flores-Naveda Enrique Díaz Barriga-Castro Neymar Camposeco-Montejo Sonia Ramírez-Barrn Fernando Borrego-Escalante Guillermo Nio-Medina Agustín Hernndez-Jurez Carlos Garza-Alonso Pablo Rodríguez-Salinas Josu I. García-Lpez 《Molecules (Basel, Switzerland)》2021,26(7)
The objective of this study was to determine the oxidative stress and the physiological and antioxidant responses of coriander plants (Coriandrum sativum) grown for 58 days in soil with zinc oxide nanoparticles (ZnO NPs) and zinc sulfate (ZnSO4) at concentrations of 0, 100, 200, 300, and 400 mg of Zn/kg of soil. The results revealed that all Zn compounds increased the total chlorophyll content (CHLt) by at least 45%, compared to the control group; however, with 400 mg/kg of ZnSO4, chlorophyll accumulation decreased by 34.6%. Zn determination by induction-plasma-coupled atomic emission spectrometry (ICP–AES) showed that Zn absorption in roots and shoots occurred in plants exposed to ZnSO4 at all concentrations, which resulted in high levels of hydrogen peroxide (H2O2) and malondialdehyde (MDA). Only at 400 mg/kg of ZnSO4, a 78.6% decrease in the MDA levels was observed. According to the results, the ZnSO4 treatments were more effective than the ZnO NPs to increase the antioxidant activity of catalase (CAT), ascorbate peroxidase (APX), and peroxidases (POD). The results corroborate that phytotoxicity was higher in plants subjected to ZnSO4 compared to treatments with ZnO NPs, which suggests that the toxicity was due to Zn accumulation in the tissues by absorbing dissolved Zn++ ions. 相似文献
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