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11.
Hovgaard MB Rechendorff K Chevallier J Foss M Besenbacher F 《The journal of physical chemistry. B》2008,112(28):8241-8249
The complex mechanisms of protein adsorption at the solid-liquid interface is of great importance in many research areas, including protein purification, biocompatibility of medical implants, biosensing, and biofouling. The protein adsorption process depends crucially on both the nanoscale chemistry and topography of the interface. Here, we investigate the adsorption of the cell-binding protein fibronectin on flat and nanometer scale rough tantalum oxide surfaces using ellipsometry and quartz crystal microbalance with dissipation (QCM-D). On the flat tantalum oxide surfaces, the interfacial protein spreading causes an increase in the rigidity and a decrease in the thickness of the adsorbed fibronectin layer with decreasing bulk protein concentration. For the tantalum oxide surfaces with well-controlled, stochastic nanometer scale roughness, similar concentration effects are observed for the rigidity of the fibronectin layer and saturated fibronectin uptake. However, we find that the nanorough tantalum oxide surfaces promote additional protein conformational changes, an effect especially apparent from the QCM-D signals, interpreted as an additional stiffening of the formed fibronectin layers. 相似文献
12.
Dr. Lars Michael Skjolding Dr. Sara Nørgaard Sørensen Dr. Nanna Bloch Hartmann M. Sc. Rune Hjorth Dr. Steffen Foss Hansen Dr. Anders Baun 《Angewandte Chemie (International ed. in English)》2016,55(49):15224-15239
The number of products on the market containing engineered nanoparticles (ENPs) has increased significantly, and concerns have been raised regarding their ecotoxicological effects. Environmental safety assessments as well as relevant and reliable ecotoxicological data are required for the safe and sustainable use of ENPs. Although the number of publications on the ecotoxicological effects and uptake of ENPs is rapidly expanding, the applicability of the reported data for hazard assessment is questionable. A major knowledge gap is whether nanoparticle effects occur when test organisms are exposed to ENPs in aquatic test systems. Filling this gap is not straightforward, because of the broad range of ENPs and the different behavior of ENPs compared to “ordinary” (dissolved) chemicals in the ecotoxicity test systems. The risk of generating false negatives, and false positives, in the currently used tests is high, and in most cases difficult to assess. This Review outlines some of the pitfalls in the aquatic toxicity testing of ENPs which may lead to misinterpretation of test results. Response types are also proposed to reveal potential nanoparticle effects in the aquatic test organisms. 相似文献
13.
Eun YJ Foss MH Kiekebusch D Pauw DA Westler WM Thanbichler M Weibel DB 《Journal of the American Chemical Society》2012,134(28):11322-11325
Persistent infections are frequently caused by dormant and biofilm-associated bacteria, which often display characteristically slow growth. Antibiotics that require rapid cell growth may be ineffective against these organisms and thus fail to prevent reoccurring infections. In contrast to growth-based antimicrobial agents, membrane-targeting drugs effectively kill slow-growing bacteria. Herein we introduce 2-((3-(3,6-dichloro-9H-carbazol-9-yl)-2-hydroxypropyl)amino)-2-(hydroxymethyl)propane-1,3-diol (DCAP), a potent broad-spectrum antibiotic that reduces the transmembrane potential of Gram-positive and Gram-negative bacteria and causes mislocalization of essential membrane-associated proteins, including MinD and FtsA. Importantly, DCAP kills nutrient-deprived microbes and sterilizes bacterial biofilms. DCAP is lethal against bacterial cells, has no effect on red blood cell membranes, and only decreases the viability of mammalian cells after ≥6 h. We conclude that membrane-active compounds are a promising solution for treating persistent infections. DCAP expands the limited number of compounds in this class of therapeutic small molecules and provides new opportunities for the development of potent broad-spectrum antimicrobial agents. 相似文献
14.
We consider a single-server cyclic polling system with three queues where the server follows an adaptive rule: if it finds one of queues empty in a given cycle, it decides not to visit that queue in the next cycle. In the case of limited service policies, we prove stability and instability results under some conditions which are sufficient but not necessary, in general. Then we discuss open problems with identifying the exact stability region for models with limited service disciplines: we conjecture that a necessary and sufficient condition for the stability may depend on the whole distributions of the primitive sequences, and illustrate that by examples. We conclude the paper with a section on the stability analysis of a polling system with either gated or exhaustive service disciplines. 相似文献
15.
WANG An-bao~ * Joseph F. Foss YUAN Chun-su Joachim Osinski . Department of Anesthesia Critical Care The University of Chicago Chicago IL USA . Shanghai Institute of Ceramics Chinese Academy of Sciences Shanghai P. R. China 《高等学校化学研究》2005,21(3):268-273
Introduction Opioidmedicationsarewidelyusedclinically forrelievingpainandasantidiarrhealsandantitus- sives.Opioidantagonistsconsistofagroupofnat- ural,semisynthetic,orsyntheticcompoundsacting onaseriesofreceptors.Concomitantwiththeabil- itytorelievepain,thesedrugshaveadverseef- fects.Side-effectsofopioidtreatmentincludenau- sea,constipation,urinaryretention,pruritus,fa- tigue,psychomimeticdisturbance,difficultmic- turition,vomitinganddependence.Thesesideef- fectsareoftensevereenoughtolimitthe… 相似文献
16.
E. G. Neganova Yu. A. Veits A. A. Borisenko V. L. Foss I. F. Lutsenko 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4)
Abstract Element-substituted acylphosphines are stable in form 2 R1P(ERn)COR2 (A), when E=Ge, Sn, Sb, P, T1 and in form R1 P=C(OERn)R2 by NMR data. The reaction 相似文献
17.
Hemmersam AG Rechendorff K Foss M Sutherland DS Besenbacher F 《Journal of colloid and interface science》2008,326(1):110-116
The adsorption of fibronectin on gold, Ti-, and Ta-oxide surfaces is investigated by means of the quartz crystal microbalance with dissipation (QCM-D) technique. The surface chemistry (gold, Ti-, and Ta-oxide) is found to influence the frequency shift observed during adsorption of the fibronectin layer with the magnitude being Delta f Au>Delta f Ti-oxide approximately Delta f Ta-oxide. Corresponding variations in the dissipation change normalised to frequency change (Delta D/Delta f) for the layer are observed. The QCM-D data are further analyzed by the random sequential adsorption (RSA) model, and adsorption rate parameter ka and footprint (a) determined, which supported the trend seen in the Delta f and Delta D/Delta f values. The value of ka found by the RSA modelling of the QCM-D resonance frequency data is found to match the ratio between the mass measured by QCM-D and the mass reported by optical techniques in literature. We conclude that comparison of the adsorption rate parameter (ka) obtained by RSA modelling of the QCM-D data with ka values obtained from RSA modelling of data obtained using optical techniques can be a route to determine the degree of hydration of the adsorbed protein layer. 相似文献
18.
Regenerative events for different queueing models are considered. The aim of this paper is to construct these events for continuous-time
processes if they are given for the corresponding discrete-time model. The construction uses so-called renovative events revealing
the property of the state at timen of the discrete-time model to be independent (in an algebraic sense) of the states referring to epochs not later thann −L (whereL is some constant) given that there are some restrictions on the “governing sequence”. Different types of multi-server and
multi-phase queues are considered. 相似文献
19.
20.
T. E. Nowlin D. Foss Smith Jr. G. S. Cieloszyk 《Journal of polymer science. Part A, Polymer chemistry》1980,18(7):2103-2119
The air oxidation of poly-p-xylylene films was studied at temperatures between 125 and 200°C. The oxidation kinetics were obtained from neutron activation (NA) oxygen analyses and infrared (IR) Spectroscopy. A correlation between the NA oxygen analyses and mechanical properties indicated that the amount of oxygen incorporated into these polymers before a significant degradation mechanical properties is about 1000 ppm for poly(dichloro-p-xylylene) and 5000 ppm for poly(monochloro-p-xylylene) or poly-p-xylylene. The activation energy for the oxidation of these polymers was about 30 kcal/mole. Long-term-use (100,000 hr) temperatures were also estimated for each of the poly-p-xylylenes studied. The 100,000-hr maximum continuous-use temperature is 112°C for poly(dichloro-p-xylylene), 72°C for poly(monochloro-p-xylylene), and 57°C for poly-p-xylylene. 相似文献