Dr. Evgeniy S. Salnikov  Dr. Marta De Zotti  Dr. Sara Bobone  Dr. Claudia Mazzuca  Dr. Jesus Raya  Dr. Alvaro S. Siano  Prof. Cristina Peggion  Prof. Claudio Toniolo  Prof. Lorenzo Stella  Prof. Burkhard Bechinger 《Chembiochem : a European journal of chemical biology》2019,20(16):2141-2150

Trichogin GA IV is a short peptaibol with antimicrobial activity. This uncharged, but amphipathic, sequence is aligned at the membrane interface and undergoes a transition to an aggregated state that inserts more deeply into the membrane, an assembly that predominates at a peptide-to-lipid ratio (P/L) of 1:20. In this work, the natural trichogin sequence was prepared and reconstituted into oriented lipid bilayers. The ¹⁵N NMR chemical shift is indicative of a well-defined alignment of the peptide parallel to the membrane surface at P/Ls of 1:120 and 1:20. When the P/L is increased to 1:8, an additional peptide topology is observed that is indicative of a heterogeneous orientation, with helix alignments ranging from around the magic angle to perfectly in-plane. The topological preference of the trichogin helix for an orientation parallel to the membrane surface was confirmed by attenuated total reflection FTIR spectroscopy. Furthermore, ¹⁹F CODEX experiments were performed on a trichogin sequence with ¹⁹F-Phe at position 10. The CODEX decay is in agreement with a tetrameric complex, in which the ¹⁹F sites are about 9–9.5 Å apart. Thus, a model emerges in which the monomeric peptide aligns along the membrane surface. When the peptide concentration increases, first dimeric and then tetrameric assemblies form, made up from helices oriented predominantly parallel to the membrane surface. The formation of these aggregates correlates with the release of vesicle contents including relatively large molecules.  相似文献   

    

Egar Mancilla-Sanchez  Claudia M. Gómez-Gutiérrez  Graciela Guerra-Rivas  Carlos A. Soto-Robles  Alfredo R. Vilchis-Nestor  Eunice Vargas  Priscy A. Luque 《International Journal of Applied Ceramic Technology》2019,16(2):438-443

We present a simple, quick, and viable way to produce hydroxyapatite (HA) from a waste by-product of the sea food industry, this was achieved by submitting the exoskeleton of the purple sea urchin Strongylocentrotus purpuratus through a chemical reaction with H₃PO₄ at 3 different times (3, 18, and 36 hours) with constant stirring at 35-40°C. The characterization of the materials was made by several techniques (FTIR, XRD, SEM-EDS, and TEM).The FTIR results confirmed the presence of the HA characteristic functional groups OH, PO₄, and CO₃, the XRD characterization showed that the synthesis of calcium phosphates such as brushite and HA was achieved by confirming the presence of its characteristic peaks, also the EDS analysis confirmed the expected HA Ca/P atomic ratio of 1.67. This work shows that we can take advantage from raw materials derived from processing sea food by giving it an added value for the biomedical industry.  相似文献   

    

Margherita Rodolfi  Benedetta Chiancone  Claudia Maria Liberatore  Andrea Fabbri  Martina Cirlini  Tommaso Ganino 《Journal of the science of food and agriculture》2019,99(13):6011-6019

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Raymundo Lira-Casas  J Efren Ramirez-Bribiesca  Hilda A Zavaleta-Mancera  Claudia Hidalgo-Moreno  Rosy G Cruz-Monterrosa  María M Crosby-Galvan  Miguel A Mendez-Rojas  Ignacio A Domínguez-Vara 《Journal of the science of food and agriculture》2019,99(5):2541-2547

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Andrea García-Pérez  José Enrique Muñoz-Hernández  Claudia Guzmán-Corona  Abel Cerón-García  César Ozuna  María Elena Sosa-Morales 《Journal of Food Processing and Preservation》2019,43(12):e14263

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Thomas Waluga  Claudia Schmidt  Georg Fieg  Stephan Scholl 《化学工程与技术》2017,40(10):1940-1945

An adequate characterization of adsorption isotherms is mandatory for chromatographic process development. Here, the elution by characteristic point (ECP) is a suitable method with low consumption of material and time. However, the ECP method requires a highly ideal behavior of the measured system. An innovative extended ECP approach is presented to characterize a non‐ideal system by the example of protein ion‐exchange adsorption. A marker, here bovine hemoglobin, is used to quantify all non‐idealities, e.g., convection, dispersion, or low number of theoretical plates. The system signal of the marker is used to compensate the system signal of the interesting solute, here bovine serum albumin. The resulting isotherm agrees well with the control results of a validated static approach.  相似文献   

    

Franziska Häfner  Claudia Kirch 《时间序列分析杂志》2017,38(6):895-922

We introduce a moving Fourier transformation for locally stationary time series, which captures the time‐varying spectral density in a similar manner as the classical Fourier transform does for stationary time series. In particular, the resulting Fourier coefficients as well as moving local periodograms are shown to be (almost all) asymptotically uncorrelated. The moving local periodogram is obtained by thinning the local periodogram to avoid multiple information present at different but close points in time. We obtain consistent estimators for the local spectral density at each point in time by smoothing the moving local periodogram. Furthermore, the moving Fourier coefficients, respectively periodograms, are well suited to adapt stationary frequency domain bootstrap methods to the locally stationary case. For the wild time frequency toggle bootstrap, it is shown that the corresponding bootstrap covariance of a global locally stationary bootstrap samples captures the time‐varying covariance structure of the underlying locally stationary time series correctly. Furthermore, this bootstrap in addition to adaptations of other frequency domain bootstrap methods is used in a simulation study to obtain uniform confidence bands for the time‐varying autocorrelation at lag 1. Finally, this methodology is applied to a wind data set.  相似文献   

    

Yeampon Nakaramontri  Charoen Nakason  Claudia Kummerlöwe  Norbert Vennemann 《Polymer Engineering and Science》2017,57(4):381-391

Carbon nanotube (CNT)‐filled epoxidized natural rubber (ENR) composites were prepared by mixing in an internal mixer and thereafter on a two‐roll mill. Silane coupling agent, namely 3‐aminopropyltriethoxy silane (APTES), was directly incorporated in the ENR‐CNT composites during mixing of rubber and CNTs in the mixer, to perform in situ functionalization. It was found that pre‐crosslinking of ENR and APTES occurred especially at high APTES concentrations, such as 0.06 mL/(g of CNTs) and caused strong CNT agglomeration in the ENR matrix. However, the pre‐crosslinking could be reduced or avoided by decreasing the APTES concentration. In the concentration range 0.01–0.015 mL/(g of CNTs) of APTES, the APTES molecules were grafted on the CNT surfaces and generated new chemical linkages with the ENR. This improved the CNT dispersion in the ENR matrix and enhanced the composite properties. A very low approximately 0.5 phr of CNT threshold concentration for electric percolation was achieved in this type of composites. Also, three‐dimensional connected CNT networks were found to form in the ENR matrix at very low APTES levels. Thus, the electrical conductivity achieved in these composites reached the level required of conductive materials. POLYM. ENG. SCI., 57:381–391, 2017. © 2016 Society of Plastics Engineers  相似文献   

    

Christian Hopmann  Sven Hendriks  Claudia Spicker  Stefan Zepnik  Frank van Lück 《Polymer Engineering and Science》2017,57(4):441-449

Cellulose acetate (CA) is a bio‐based polymer suitable to replace foamed polystyrene (PS) in packaging applications. Foam trays can be produced by thermoforming of extruded sheets foamed with physical blowing agents. In this paper, the effects of various process settings and the calibration of the sheet on foam morphology and surface quality of extruded CA sheets are presented. Different contact cooling options were applied in order to investigate their influence on surface roughness, density, and morphology of the sheets. By adjusting cooling parameters, blowing agent formulation, and process settings, smooth foam sheets with a surface roughness below 10 µm and a density in the range of 150 kg m^?3 were produced. POLYM. ENG. SCI., 57:441–449, 2017. © 2016 Society of Plastics Engineers  相似文献   

    

Lucia Manna  Claudia Carotenuto  Roberto Nigro  Amedeo Lancia  Francesco Di Natale 《加拿大化工杂志》2017,95(9):1781-1788

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