Impact of foliar spray of zinc oxide nanoparticles on the photosynthesis of Pisum sativum L. under salt stress.

This study investigates the impacts of zinc oxide nanoparticles: bare (ZnO NPs) and ZnO NPs coated with silicon shell (ZnO-Si NPs), on Pisum sativum L. under physiological and salt stress conditions. The experimental results revealed that the foliar spray with ZnO-Si NPs and 200 mg/L ZnO NPs did not influence the stomata structure, the membrane integrity, and the functions of both photosystems under physiological conditions, while 400 mg/L ZnO-Si NPs had beneficial effects on the effective quantum yield of photosystem II (PSII) and the photochemistry of photosystem I (PSI). On the contrary, small phytotoxic effects were registered after spraying with 400 mg/L ZnO NPs accompanied by stimulation of the cyclic electron flow around PSI and an increase of the non-photochemical quenching (NPQ). The results also showed that both types of NPs (with exception of 400 mg/L ZnO NPs) decrease the negative effects of 100 mM NaCl on the photochemistry of PSI (P700 photooxidation) and PSII (qp, Fv/Fm, Fv/Fo, ΦPSII, Φexc), as well as on the pigment content, stomata closure and membrane integrity. The protective effect was stronger after spraying with ZnO-Si NPs in comparison to ZnO NPs, which could be due to the presence of Si coating shell. The role of Si shell is discussed.

Response of some biophysical properties of blood to changes in the perfusion flow rate during cardiopulmonary bypass.

Cardiopulmonary bypass (CPB) is a safe support system during major cardiac operations because it allows the distribution of adequately oxygenated blood to the entire body. The optimal perfusion flow to be used during hypothermic CPB remains a controversial issue. In the present study, the effect of different flows and pressures on oxygen delivery, extraction and consumption was compared. Such an effect was evaluated for 40 patients undergoing open-heart surgery using CPB (membrane oxygenator) and systemic hypothermia. The patients were randomized into two groups (20 each) according to the flow and pressure (low flow, low pressure and high flow, high pressure). The electrical impedance from 50 Hz to 10 MHz for blood samples and erythrocytes for both groups was also measured at different time intervals (before-, during and post-CPB). No significant change for low flow group was recorded (p > 0.05) while the dielectric properties of the high-flow group were greatly affected by the time of operation. Hence, low flow can be safely used in young patients without any organ impairment or carotid artery disease, while high flow should be used for patients with any organ dysfunction, at the initiation of CPB and during rewarming to compensate for the increase in oxygen consumption and the need for better perfusion pressure.