Simplified mathematical model of proton exchange membrane fuel cell based on horizon fuel cell stack

This paper presents a simplified zero-dimensional mathematical model for a self-humidifying proton exchange membrane (PEM) fuel cell stack of 1 kW. The model incorporates major electric and thermodynamic variables and parameters involved in the operation of the PEM fuel cell under different operational conditions. Influence of each of these parameters and variables upon the operation and the performance of the PEM fuel cell are investigated. The mathematical equations are modeled by using Matlab–Simulink tools in order to simulate the operation of the developed model with a commercial available 1 kW horizon PEM fuel cell stack (H-1000), which is used for the purposes of model validation and tuning of the developed model. The model can be extrapolated to higher wattage fuel cells of similar arrangements. New equation is presented to determine the impact of using air to supply the PEM fuel cell instead of pure oxygen upon the concentration losses and the output voltage when useful current is drawn from it

Improved functionalization of oleic acid-coated iron oxide nanoparticles for biomedical applications

Superparamagnetic iron oxide nanoparticles can providemultiple benefits for biomedical applications in aqueous environments such asmagnetic separation or magnetic resonance imaging. To increase the colloidal stability and allow subsequent reactions, the introduction of hydrophilic functional groups onto the particles’ surface is essential. During this process, the original coating is exchanged by preferably covalently bonded ligands such as trialkoxysilanes. The duration of the silane exchange reaction, which commonly takes more than 24 h, is an important drawback for this approach. In this paper, we present a novel method, which introduces ultrasonication as an energy source to dramatically accelerate this process, resulting in high-quality waterdispersible nanoparticles around 10 nmin size. To prove the generic character, different functional groups were introduced on the surface including polyethylene glycol chains, carboxylic acid, amine, and thiol groups. Their colloidal stability in various aqueous buffer solutions as well as human plasma and serum was investigated to allow implementation in biomedical and sensing applications.status: publishe

Issues and Changes Related to Dissonant Heritage: a Case from Jewish and Polish Heritage in the Small Towns of Western Ukraine

This study presents and analyzes the cases of “dissonant heritage” issues in areas characterized by multicultural backgrounds and conflicting historical narratives. Contrasting trends, which include persistent or resurgent one-sided nationalistic representations, as well as more inclusive and plural emerging trends in heritage promotion, are compared and discussed through the example of three selected towns located in Western Ukraine. The three towns were selected among others as representative of formerly multiethnic communities now turned into ethnically homogeneous ones, where minority heritage shows different degrees of neglect or promotion, in order to understand which aspects of history, memory, and heritage have been selected and promoted or not, and why. The study results show the rise of inclusive narratives in which minority heritage, with the related historical memories, rather than a menace for national cohesion, can become a solid opportunity for local development and for cultural, social, and political pluralism in marginal areas