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排序方式: 共有192条查询结果,搜索用时 46 毫秒
101.
102.
Dennis Kubiczek Carolin Flaig Heinz Raber Steffen Dietz Ann‐Kathrin Kissmann Thomas Heerde Nicholas Bodenberger Andreas Wittgens Melaine Gonzlez‐Garcia Fan Kang Octavio L. Franco Ludger Staendker Anselmo J. Otero‐Gonzlez Paul Walther Kay E. Gottschalk Tanja Weil Frank Rosenau 《Macromolecular bioscience》2020,20(4)
The pathogenic yeast Candida auris has received increasing attention due to its ability to cause fatal infections, its resistance toward important fungicides, and its ability to persist on surfaces including medical devices in hospitals. To brace health care systems for this considerable risk, alternative therapeutic approaches such as antifungal peptides are urgently needed. In clinical wound care, a significant focus has been directed toward novel surgical (wound) dressings as first defense lines against C. auris. Inspired by Cerberus the Greek mythological “hound of Hades” that prevents the living from entering and the dead from leaving hell, the preparation of a gatekeeper hybrid hydrogel is reported featuring lectin‐mediated high‐affinity immobilization of C. auris cells from a collagen gel as a model substratum in combination with a release of an antifungal peptide drug to kill the trapped cells. The vision is an efficient and safe two‐layer medical composite hydrogel for the treatment of severe wound infections that typically occur in hospitals. Providing this new armament to the repertoire of possibilities for wound care in critical (intensive care) units may open new routes to shield and defend patients from infections and clinical facilities from spreading and invasion of C. auris and probably other fungal pathogens. 相似文献
103.
In this work, we use nonequilibrium molecular dynamics to simulate a contraction–expansion flow of various systems, namely melts with molecules of various conformations (linear, branched, and star), linear molecules in solution, and a reference Lennard–Jones fluid. The equations for Poiseuille flow are solved using a multiple time scale algorithm extended to nonequilibrium situations. Simulations are performed at constant temperature using the Nose–Hoover dynamics. The main objective of this analysis is to investigate the molecular origin of pressure drop along planar contraction–expansion geometry, varying the length of the contraction, and the effect that different molecular conformations have on the resulting pressure drop along the geometry. Pressure drop is closely related to mass distribution (in neutral and gradient directions) and branching index of molecules. Also, it is shown that remarkable increases of pressure drops are also possible in planar geometries, provided large extensional viscosities combined with moderate values of the first normal stress difference in shear are considered, in addition to considerable reductions of the flow area at the contraction region. 相似文献
104.
Juan Paulo?Garcia-Sandoval Fernando?Bautista Jorge Emilio?Puig Octavio?ManeroEmail author 《Rheologica Acta》2017,56(9):765-778
In this work, we study the diffusion of the interface between bands in wormlike micellar solutions that exhibit shear banding flow regimes, namely, systems undergoing coexistence of states of different shear rates along a constant stress plateau. The migration of the interface between bands possessing different birefringence levels is predicted by the BMP (Bautista-Manero-Puig) model in which a structural parameter (the fluidity) presents two states with differing order separated by an interface. The mechanical potential derived from the constitutive equations and a diffusion term for the structure evolution equation predict various time scales of interface migration at the inception of shear flow and under shear-rate changes along the plateau stress. It is shown that the extremes of the plateau (binodals) correspond to the minima in the mechanical potential as a function of fluidity or shear rate. We also predict the dependence of the diffusive length scale on the applied shear rate. 相似文献
105.
106.
Octavio Betancourt 《纯数学与应用数学通讯》1988,41(5):551-568
A fully three-dimensional spectral code has been developed and implemented. It computes three-dimensional equilibria using the variational approach, by minimizing the potential energy subject to appropriate constraints. A second minimization, with an additional constraint, is used to examine the stability of solutions. The magnetic field representation allows for non-nested flux surfaces. Thus it can be used to study solutions with islands and variation of the potential energy with respect to topology changes. A spectral representation in the toroidal and poloidal angles, coupled with a special choice of collocation points in the radial direction results in greatly enhanced resolution. A fast iterative method was developed, with the number of iterations required for convergence independent of the mesh size. Residuals converge exponentially to the round-off error, allowing the potential energy to be computed to the eight-digit accuracy required for nonlinear stability analysis. A small amount of artificial viscosity may be needed for convergence in cases where low-order resonances are present in the plasma region. Numerical results show convergence to known axially symmetric equilibrium solutions, as well as close agreement with eigenvalue calculations in helically symmetric stellarator configurations. Solutions exhibiting island formations are found to have lower potential energy than that of the nearby nested case. Internal modes are found to localize inside the resonant surface, with the eigenfunction having sharp gradients at the resonant surface. 相似文献
107.
The rheological characterization and modeling of a series of polybutadienes obtained by anionic solution polymerization is
presented in this work. The polybutadienes are synthesized using two different initiators: R,R′,R′′-silyloxyalkyllithium (F1)
and R,R′,R′′-silylalkyllithium (F3). In addition, a polybutadiene obtained with a conventional alkyllithium initiator (n-butyllithium) is used as a reference.
The rheological characterization is carried out under small amplitude oscillatory shear in the stress-controlled mode. Microstructure,
molecular weight, and molecular weight distribution are determined by FTIR and GPC. The vinyl content of the polybutadienes
synthesized using the functionalized initiators is similar to that obtained with n-butyllithium (8–11%). Materials obtained with F1 show a relatively low polydispersity within a narrow molecular weight range
(250,000–300,000 g/mol), while samples obtained with F3 cover a wider range of molecular weights (65,000–670,000 g/mol) and
display higher values of polydispersity. In all cases, a parallel reaction using propylene oxide in the termination step is
done to place a functional group at the chain ends. The effect of this group on the rheological behavior appears to be negligible.
Three rheological models are used and their predictions of the experimental data are compared. The models include the Doi
and Edwards reptation model, expressions using a discrete spectrum of relaxation times based in the rubber-like liquid constitutive
equation and the fractional Maxwell equation in which a given analytical relaxation-spectrum is used. Relevant relations are
obtained between the models' parameters and the molecular properties of these systems, which in turn are related to the presence
of functional groups at the polymer chain ends. 相似文献
108.
Vasso Apostolopoulos Joanna Bojarska Tsun-Thai Chai Sherif Elnagdy Krzysztof Kaczmarek John Matsoukas Roger New Keykavous Parang Octavio Paredes Lopez Hamideh Parhiz Conrad O. Perera Monica Pickholz Milan Remko Michele Saviano Mariusz Skwarczynski Yefeng Tang Wojciech M. Wolf Taku Yoshiya Janusz Zabrocki Piotr Zielenkiewicz Maha AlKhazindar Vanessa Barriga Konstantinos Kelaidonis Elham Mousavinezhad Sarasia Istvan Toth 《Molecules (Basel, Switzerland)》2021,26(2)
Peptides are fragments of proteins that carry out biological functions. They act as signaling entities via all domains of life and interfere with protein-protein interactions, which are indispensable in bio-processes. Short peptides include fundamental molecular information for a prelude to the symphony of life. They have aroused considerable interest due to their unique features and great promise in innovative bio-therapies. This work focusing on the current state-of-the-art short peptide-based therapeutical developments is the first global review written by researchers from all continents, as a celebration of 100 years of peptide therapeutics since the commencement of insulin therapy in the 1920s. Peptide “drugs” initially played only the role of hormone analogs to balance disorders. Nowadays, they achieve numerous biomedical tasks, can cross membranes, or reach intracellular targets. The role of peptides in bio-processes can hardly be mimicked by other chemical substances. The article is divided into independent sections, which are related to either the progress in short peptide-based theranostics or the problems posing challenge to bio-medicine. In particular, the SWOT analysis of short peptides, their relevance in therapies of diverse diseases, improvements in (bio)synthesis platforms, advanced nano-supramolecular technologies, aptamers, altered peptide ligands and in silico methodologies to overcome peptide limitations, modern smart bio-functional materials, vaccines, and drug/gene-targeted delivery systems are discussed. 相似文献
109.
Alves WA Antunes OA 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,67(3-4):847-851
Raman spectra of pure liquid dimethylsulfoxide (DMSO) and of binary mixtures of formamide (FA) and DMSO in different compositions were obtained. The vibrations involving the SO functional group in the band envelope at ca. 1050 cm(-1) of pure liquid DMSO are assigned to monomers, dimers and higher aggregates of DMSO. The appearance of a new band at 1024 cm(-1), whose intensity shows large dependence on the FA concentration, is assigned to a FA-DMSO adduct. This has been possible due to the two H-bond donor sites of FA and the strong donor character of DMSO that become the environment propitious for the donor-acceptor reaction. Quantitative analysis performed in the SO stretching region in the binary mixtures gives a 1:1 stoichiometry in this adduct in the limit of infinite dilution. This proportion is in full agreement with our previous determination for the FA-ACN adduct. The experimental evidence of the 1:1 FA-DMSO adduct is presented for the first time using Raman spectroscopy. The results described here open new possibilities to study the acid-base reactions nature of FA adducts. 相似文献
110.
Rodrigo Osorio-Arciniega Manuel García-Hiplito Octavio Alvarez-Fregoso Marco Antonio Alvarez-Perez 《Molecules (Basel, Switzerland)》2021,26(24)
Composite scaffolds are commonly used strategies and materials employed to achieve similar analogs of bone tissue. This study aims to fabricate 10% wt polylactic acid (PLA) composite fiber scaffolds by the air-jet spinning technique (AJS) doped with 0.5 or 0.1 g of zirconium oxide nanoparticles (ZrO2) for guide bone tissue engineering. ZrO2 nanoparticles were obtained by the hydrothermal method and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). SEM and fourier-transform infrared spectroscopy (FTIR) analyzed the synthesized PLA/ZrO2 fiber scaffolds. The in vitro biocompatibility and bioactivity of the PLA/ZrO2 were studied using human fetal osteoblast cells. Our results showed that the hydrothermal technique allowed ZrO2 nanoparticles to be obtained. SEM analysis showed that PLA/ZrO2 composite has a fiber diameter of 395 nm, and the FITR spectra confirmed that the scaffolds’ chemical characteristics are not affected by the synthesized technique. In vitro studies demonstrated that PLA/ZrO2 scaffolds increased cell adhesion, cellular proliferation, and biomineralization of osteoblasts. In conclusion, the PLA/ZrO2 scaffolds are bioactive, improve osteoblasts behavior, and can be used in tissue bone engineering applications. 相似文献