Microoxygraph Device for Biosensoristic Applications

Oxygen consumption rate (OCR) is a significant parameter helpful to determine in vitro respiratory efficiency of living cells. Oxygen is an excellent oxidant and its electrocatalytic reduction on a noble metal allows accurately detecting it. By means of microfabrication technologies, handy, low-cost, and disposable chip can be attained, minimizing working volumes and improving sensitivity and response time. In this respect, here is presented a microoxygraph device (MOD), based on Clark’s electrode principle, displaying many advantageous features in comparison to other systems. This lab-on-chip platform is composed of a three-microelectrode detector equipped with a microgrooved electrochemical cell, sealed with a polymeric reaction chamber. Au working/counter electrodes and Ag/AgCl reference electrode were fabricated on a glass slide. A microchannel was realized by photoresist lift-off technique and a polydimethylsiloxane (PDMS) nanoporous film was integrated as oxygen permeable membrane (OPM) between the probe and the microreaction chamber. Electrochemical measurements showed good reproducibility and average response time, assessed by periodic injection and suction of a reducing agent. OCR measurements on 3T3 cells, subjected, in real time, to chemical stress on the respiratory chain, were able to show that this chip allows performing consistent metabolic analysis

MPC for tracking with optimal closed-loop performance

Abstract-This paper deals with the tracking problem for constrained linear systems using a model predictive control (MPC) law. As it is well known, MPC provides a control law suitable for regulating a constrained linear system to a given target steady state. Asymptotic stability and constraint fulfilment for any finite prediction horizon is typically ensured by means of a suitable choice of the terminal cost and constraint. However, when the target operating point changes, the feasibility of the controller may be lost and the controller fails to track the reference. Recently, a novel MPC formulation has been proposed to solve this problem, ensuring feasibility and asymptotic convergence to any admissible steady state. On the other hand, this control law can not ensure the local optimality of the proposed controller, which is a desirable property of predictive controllers. In this paper, this controller is extended considering a generalized offset cost function. Sufficient conditions on this function are given to ensure the local optimality property. Besides, this novel formulation allows to consider as target operation points, states which may be not equilibrium points of the linear systems. In this case, it is proved in this paper that the proposed control law steers the system to an admissible steady state (different to the target) which is optimal with relation to the offset cost function. Thanks to the proposed generalization, the offset cost function could be chosen according to some steady performance criterium. Therefore, the proposed controller for tracking achieves an optimal closed-loop performance during the transient as well as an optimal steady state in case of not admissible target. These properties are illustrated in an example

Centrifugation force and time alter CASA parameters and oxidative status of cryopreserved stallion sperm

Conventional sperm selection techniques used in ARTs rely on centrifugation steps. To date, the different studies reported on the effects of centrifugation on stallion sperm motility provided contrasting results and do not include effects on mitochondrial functionality and different oxidative parameters. The effects of different centrifugation protocols (300 ×g for 5’, 300 ×g for 10’, 1500 ×g for 5’ and 1500 ×g for 10’ vs no centrifugation) on motility and oxidative status in cryopreserved stallion sperm, were analyzed. After centrifugation, almost all motility parameters were significantly altered, as observed by computer-assisted sperm analysis. A polarographic assay of oxygen consumption showed a progressive decrease in mitochondria respiration from the gentlest to the strongest protocol. By laser scanning confocal microscopy, significant reduction of mitochondrial membrane potential, at any tested protocol, and time-dependent effects, at the same centrifugal force, were found. Increased DNA fragmentation index at any tested protocol and time-dependent effects at the same centrifugal force were found, whereas increased protein carbonylation was observed only at the strongest centrifugal force. These results provide more comprehensive understandings on centrifugation-induced effects on cryopreserved stallion sperm and suggest that, even at a weak force for a short time, centrifugation impairs different aspects of equine sperm metabolism and functionality

Self-Perceived Clinical Competence of Nurses in Different Working Experiences: A Cross-Sectional Study

Background: Competence is an essential concept for measuring nurses’ performance in terms of effectiveness and quality. To this end, our analysis highlighted the process of acquiring competencies, their self-evaluation into clinical practice, and how their proficiency levels change throughout the nursing career. In detail, this research explored nurses’ perceived level of competence and the factors that influence it in different contexts. Methods: A cross-sectional survey using a structured questionnaire to assess the nursing participants’ perception of their competencies in different clinical settings was accomplished. Results: A descriptive and bivariate analysis was performed on 431 nurses. Most respondents assessed their level of competence to be higher than their roles required. The Kruskal–Wallis test confirmed that nursing experience was a relevant factor influencing nursing competencies. Conclusions: We suggest improving the competence of practicing nurses, using experience as a measurable effect of their development

Aneurysms and pseudoaneurysms in dialysis access

Aneurysms are a common and often difficult complication seen with arteriovenous vascular access for haemodialysis. The purpose of this narrative review is to define and describe the scale of the problem and suggested therapeutic strategies. A narrative review of the published literature illustrated by individual cases is presented with the aim of summarising the relevant literature. The definitions of aneurysm are inconsistent throughout the literature and therefore systematic review is impossible. They vary from qualitative descriptions to quantitative definitions using absolute size, relative size and also size plus characteristics. The incidence and aetiology are also ill defined but separation into true aneurysms and false, or pseudoaneurysms may be helpful in planning treatment, which may be conservative, surgical or radiological. The lack of useful definitions and classification along with the multitude of management strategies proposed make firm evidence based conclusions difficult to draw. Further robust well designed studies are required to define best practice for this common problem

Distributed control of chemical process networks

In this paper, we present a review of the current literature on distributed (or partially decentralized) control of chemical process networks. In particular, we focus on recent developments in distributed model predictive control, in the context of the specific challenges faced in the control of chemical process networks. The paper is concluded with some open problems and some possible future research directions in the area

Liver support systems

none4Liver insufficiency is a dramatic syndrome, with multiple organ involvement. A multiplicity of toxic substances (hydrophilic like ammonia and lipophylic like bilirubin or bile acids or mercaptans) are released into the systemic circulation, thus altering many enzymatic cellular processes. The patient’s death while on the transplantation waiting list is frequent, because of organ scarcity. Systems to support liver function may be useful to avoid further complications due to the typical toxic state, “bridging” the patients to the transplantation, or, in the event of an acute decompensation of a chronic liver disease, sustain liver function long enough to permit organ’s regeneration and functional recovery. An ideal liver support system should substitute the main functions of the liver (detoxification, synthesis and regulation). Extracorporeal systems now available may be totally artificial or bio-artificial. While the first are only able to perform detoxification, the second may add the functions of synthesis (plasma proteins, coagulation factors …) and regulation (neurotransmitters). Bioartificial liver working with isolated hepatocytes and a synthetic membrane in an extracorporeal system, are however still far from being ready for clinical use. At present, liver insufficiency may be treated with an extracorporeal support technology aimed either to detoxification alone or to a real purification. Charcoal hemoperfusion or exchange/absorption resins may be used for blood detoxification. Blood or plasma-exchange, from a theoretical point of view, could be suited for a polyvalent intoxication, as liver failure is; however, the multi-compartmental distribution of some solutes largely endangers the efficacy of these procedures. Selective plasmapheresis techniques are now available for some solutes (e.g. styrene for bilirubin) and may progressively reduce the plasma levels and presumably the deposits of the solute. Novel treatments introduced to improve detoxification, mainly of the protein-bound substances, are the molecular adsorbent recirculation system system (MARS) and Prometheus systems. MARS performs an albumin dialysis, where albumin is the exogenous carrier for the toxic substances, and different experiences have proved its efficacy mainly in the treatment of hepatic encephalopathy, while data on survival are still limited to small case series. With Prometheus, the most recent system developed for a wide detoxification, albumin-bound toxins are directly removed in two separate cartridges with different solute affinity, without the need for exogenous albumin; plasmadsorption is then coupled with a real dialysis process. After initial, promising results, the efficacy of Prometheus in the patients hard end-points will be evaluated in a large international trial. On the whole, liver support systems may offer, in many cases, a survival benefit. Stem cells are however, even in this filed, the real, great hope for the future of patients with end-stage liver disease.noneSantoro A.; Mancini E.; Ferramosca E.; Faenza S.Santoro A.; Mancini E.; Ferramosca E.; Faenza S