over 30 min), and an intravenous infusion of GIP (1.0 pmol ⅐ kg ؊1 ⅐ min ؊1 over 30 min) were performed. Venous blood samples were drawn for the determination of glucose (glucose oxidase), insulin, C-peptide, GLP-1 (total and intact), and GIP (total and intact; specific immunoassays). Plasma levels of GIP (3-42) and GLP-1 (9-36 amide) were calculated. Statistics were performed using repeated-measures and one-way ANOVA. After the oral glucose load, plasma concentrations of intact GLP-1 and intact GIP reached similar levels in both groups (P ؍ 0.31 and P ؍ 0.87, respectively). The concentrations of GIP (3-42) and GLP-1 (9-36 amide) were significantly higher in the patients than in the control subjects (P ؍ 0.0021 and P ؍ 0.027, respectively). During and after the exogenous infusion, GLP-1 (9-36 amide) and GIP (3-42) reached higher plasma concentrations in the CRI patients than in the control subjects (P < 0.001 and P ؍ 0.0033, respectively), whereas the plasma levels of intact GLP-1 and GIP were not different between the groups (P ؍ 0.29 and P ؍ 0.27, respectively). Plasma half-lives were 3.4 ؎ 0.6 and 2.3 ؎ 0.4 min for intact GLP-1 (P ؍ 0.13) and 5.3 ؎ 0.8 and 3.3 ؎ 0.4 min for the GLP-1 metabolite (P ؍ 0.029) for CRI patients vs. healthy control subjects, respectively. Plasma half-lives of intact GIP were 6.9 ؎ 1.4 and 5.0 ؎ 1.2 min (P ؍ 0.31) and 38.1 ؎ 6.0 and 22.4 ؎ 3.0 min for the GIP metabolite (P ؍ 0.032) for CRI patients vs. healthy control subjects, respectively. Insulin concentrations tended to be lower in the patients during all experiments, whereas C-peptide levels tended to be elevated. These data underline the importance of the kidneys for the final elimination of GIP and GLP-1. The initial dipeptidyl peptidase IV-mediated degradation of both hormones is almost unaffected by impairments in renal function. Delayed elimination of GLP-1 and GIP in renal insufficiency may influence the pharmacokinetics and pharmacodynamics of dipeptidyl peptidase IV-resistant incretin derivatives to be used for the treatment of patients with type 2 diabetes. Diabetes 53:654 -662, 2004
Cryogels from noble metal NPs have proven to be highly efficient catalysts due to their high specific surface area which increases the mass transfer channels and catalytic active sites. By using metal oxides as co-catalysts, the costs of the material can be significantly reduced, while the catalytic activity can remain the same or even improve due to synergetic effects. In this work, we synthesize different cryogel thin films supported on modified ITO substrates from Pt, Pd nanoparticles (NPs), and mixtures of these noble metals with γ-Fe2O3 NPs in a very low concentration (1 wt% of the noble metal). Structural and elemental analysis of the samples are performed, along with the measurement and analysis of their catalytic activity. The electrocatalytic activity of the cryogels towards ethanol oxidation reaction (EOR) in alkaline media was evaluated by means of cyclic voltammetry. By mixing γ-Fe2O3 NPs with Pt or Pd NPs in the cryogel structure, we observe increased tolerance against poisonous surface intermediates produced during the EOR. Moreover, we observe an increase in the catalytic activity towards EOR in the case of the 1 wt% Pd/γ-Fe2O3 cryogel, making them promising materials for the development of direct ethanol fuel cells.
Due to their unique optical properties, nanoparticles are well suited for heating by laser irradiation. In this context, colloidally dispersed particles are of particular interest because in conventional ways of heating, the maximum attainable temperature is limited by the boiling point of the solvent. With the right choice of the used laser wavelength, it is possible to selectively heat these particles above the melting point of the material whereas the surrounding and laser-transparent medium remains comparatively cold. This type of laser process is called laser melting in liquids (LML). To further investigate the possibilities of laser-induced heating processes, colloidally dispersed copper(II) oxide (CuO) nanoparticles were synthesized, dispersed in ethanol, and irradiated with a nanosecond-pulsed Nd:YAG laser. In this way, a laser-induced phase transition into the copper richer copper(I) oxide (Cu 2 O) phase and into elemental copper can be observed. The conversion process is followed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), selected area electron diffraction (SAED), and UV−vis spectroscopy. It is shown that in the initial LML process a minimum particle size of 23−29 nm is required for a successful phase transition likely due to the size dependent heating efficiency, cooling effects, and the formation of nanobubbles.
The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/smll.202206379.
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