213 research outputs found

    On the third coefficient of TYZ expansion for radial scalar flat metrics

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    We classify radial scalar flat metrics with constant third coeffcient of its TYZ expansion. As a byproduct of our analysis we provide a characterization of Simanca's scalar flat metric.Comment: 14 page

    Extremal Kaehler metrics induced by finite or infinite dimensional complex space forms

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    In this paper we address the problem of studying those complex manifolds MM equipped with extremal metrics gg induced by finite or infinite dimensional complex space forms. We prove that when gg is assumed to be radial and the ambient space is finite dimensional then (M,g)(M, g) is itself a complex space form. We extend this result to the infinite dimensional setting by imposing the strongest assumption that the metric gg has constant scalar curvature and is well-behaved (see Definition 1 in the Introduction). Finally, we analyze the radial Kaehler-Einstein metrics induced by infinite dimensional elliptic complex space forms and we show that if such a metric is assumed to satisfy a stability condition then it is forced to have constant non-positive holomorphic sectional curvature.Comment: 24 page

    the molecular motion of bovine serum albumin under physiological conditions is ion specific

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    Specific ion effects on the Brownian motion of BSA protein under physiological conditions give new useful insights into the electrolyte–protein interactions and the molecular mechanisms involved in the Hofmeister effect

    On canonical radial Kaehler metrics

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    We prove that a radial Kaehler metric g is Kaehler-Einstein if and only if one of the following conditions is satisfied: 1. g is extremal and it is associated to a Kaehler-Ricci soliton; 2. two different generalized scalar curvatures of g are constant; 3. g is extremal (not cscK) and one of its generalized scalar curvature is constant.Comment: 11 pages. arXiv admin note: text overlap with arXiv:2105.1069

    A bienzymatic biocatalyst constituted by glucose oxidase and Horseradish peroxidase immobilized on ordered mesoporous silica

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    It is presently extremely challenging to realize an active immobilized multi-enzyme biocatalyst which allows to run in vitro multi-step cascade reactions. This work deals with the obtainment of a bienzymatic immobilized biocatalyst constituted by Glucose Oxidase (GOx) and Horseradish Peroxidase (HRP) immobilized onto SBA-15 mesoporous silica. The effect of co-immobilization (GOx/HRP@SBA-15) versus the separated immobilization (GOx@SBA-15/HRP@SBA-15), and the effect of covalent versus physical immobilization, on protein loading and enzymatic activity were investigated. Regardless the different immobilization strategy used, it was found that the catalytic activity could be retained only if the immobilized bienzymatic biocatalyst was kept wet. The obtained wet GOx/HRP@SBA-15 biocatalyst could be recycled 14 times keeping a good activity. Finally, the bienzymatic biocatalyst was tested for the oxidation of two model phenolic (caffeic acid and ferulic acid) pollutants of agricultural wastewaters, as olive mill wastewaters (OMWs). The biocatalyst was able to reach a 70% conversion within 15 min

    Polysaccharides as drug delivery systems for different administration routes

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    Polysaccharides are biocompatible and biodegradable long carbohydrate molecules organized in repeated monosaccharide units interconnected with glycosidic bonds. These polymers constitute a large source of biomaterials for drug vehicles, controlled drug delivery, tissue engineering etc. The ionic character and the presence of reactive functional group led them to be good candidates for the development of controlled release formulations. They are well tolerated by living tissues and body cavities due to their biocompatibility and biodegradability. In fact, polysaccharides have been widely proposed as drug delivery devices for many administration routes such as oral, parenteral, ophthalmic, nasal and transdermal route. Furthermore, polysaccharides can be considered appropriate for tissue engineering thanks to their mechanical and biochemical functions and ability to deliver and foster cells. The aim of the present work was the development of polysaccharides based platform formulations as novel and suitable delivery systems of specific drugs into determined anatomical districts

    ON CANONICAL RADIAL KÄHLER METRICS

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    We prove that a radial Kähler metric g is Kähler-Einstein if and only if one of the following conditions is satisfied: 1. g is extremal and it is associated to a Kähler-Ricci soliton; 2. two different generalized scalar curvatures of g are constant; 3. g is extremal (not cscK) and one of its generalized scalar curvature is constant

    Adsorption and release of ampicillin antibiotic from ordered mesoporous silica

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    In this work the adsorption and the release of ampicillin - a β-lactam penicillin-like antibiotic - from MCM-41, SBA-15, and (amino functionalized) SBA-15-NH2 ordered mesoporous silica (OMS) materials were investigated. The silica matrices differ for their pore size (SBA-15 vs. MCM-41) mainly, and also for surface charge (SBA-15 and MCM-41, vs. SBA-15-NH2). OMS samples were characterized through small-angle X-rays scattering (SAXS), transmission electron microscopy (TEM), N2 adsorption–desorption isotherms, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and potentiometric titrations. The quantification of immobilized and released ampicillin was monitored by mean of UV–Vis spectroscopy. Experimental adsorption isotherms evidenced that ampicillin's loading is not related to the pore size (dBJH) of the adsorbent. Indeed the maximal loadings were 237 mg/g for SBA-15 (dBJH = 6.5 nm), 278 mg/g for MCM-41 (dBJH = 2.2 nm), and 333 mg/g for SBA-15-NH2 (dBJH = 5.6 nm). Loading seems, instead, to be related to the surface charge density (σ) of the sorbent surface. Indeed, at pH 7.4 ampicillin drug is negatively charged and likely prefers to interact with SBA-15-NH2 (σSBA-15-NH2 = +0.223 C m−2) rather than the slightly negatively charged silicas (σSBA-15 = âˆ’0.044 C m−2 and σMCM-41 = âˆ’0.033 C m−2). Similarly, ampicillin release is affected by interfacial interactions. Indeed, we found a burst release from pure silica samples (SBA-15 and MCM-41), whereas a sustained one from SBA-15-NH2 sample. We explain this behavior as a result of an attractive interaction between the protonated amino group of SBA-15-NH2 and the negatively charged carboxylate group of ampicillin. In summary, in order to obtain a sustained drug release, the chemical nature of the matrix's surface plays a role which is more important than its textural features. SBA-15-NH2 matrix is hence a suitable candidate for local sustained release of antibiotic drugs
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