Adsorption of Tetracycline and Sulfadiazine onto Three Different Bioadsorbents in Binary Competitive Systems

Different antibiotics contained in manure, slurry, wastewater or sewage sludge are spread into the environment. The harmful effects of these antibiotics could be minimized by means of immobilization onto bioadsorbent materials. This work investigates the competitive adsorption/desorption of tetracycline (TC) and sulfadiazine (SDZ) onto pine bark, oak ash and mussel shell. The study was carried out using batch-type experiments in binary systems (with both antibiotics present simultaneously), adding 5 equal concentrations of the antibiotics (between 1 and 50 µmol L−1). The adsorption percentages were higher for TC (close to 100% onto pine bark and oak ash, and between 40 and 85% onto mussel shell) than for SDZ (75–100% onto pine bark, and generally less than 10% on oak ash and mussel shell). Pine bark performed as the best adsorbent since TC adsorption remained close to 100% throughout the entire concentration range tested, while it was between 75 and 100% for SDZ. Desorption was always higher for SDZ than for TC. The results of this study could be useful to design practices to protected environmental compartments receiving discharges that simultaneously contain the two antibiotics here evaluated, and therefore could be relevant in terms of protection of the environment and public health.

Dynamics in a Delayed Competition System on a Weighted Network

In this paper, we study the stability of positive steady states in a delayed competition system on a weighted network, which does not satisfy the comparison principle appealing to classical competitive systems. By introducing some auxiliary equations and constructing proper contracting rectangles, we present some sufficient conditions on the stability of the unique positive steady state. Moreover, some numerical examples are given to explore the complex dynamics of this nonmonotone model, which implies the nontrivial roles of weights and time delays.

The Organizational Field of Blood Collection: A Multilevel Analysis of Organizational Determinants of Blood Donation in Europe

Maintaining an adequate blood supply for transfusion poses a pressing challenge to society. We argue that this challenge has not been adequately addressed in previous research. Building upon Healy’s seminal work on ‘blood-collection regimes’ and the subsequent shift towards a field-level approach that broadens the analytical focus beyond the dyadic relationship between donors and organizations, we embed the act of blood donation within the organizational field in which blood establishments operate. We assume that varying modes of governance shape the organizational practices of donor recruitment and blood collection. Our analysis is based on Eurobarometer data from 2014 (number of countries = 28; number of individuals = 19,363). The results identify considerable variance in donation rates according to field characteristics in terms of hierarchical centralization and competitiveness. Decentralized systems without competition perform worst in terms of the recruitment of (first-time) blood donors. Competitive systems in which several different bodies share responsibility for the provision of blood to patients yield the highest donation rates.