Undoped nanocrystalline diamond (NCD) films less than 1 μm thick grown on Si (100) silicon by microwave plasma-assisted chemical vapor deposition at a frequency of 2.45 GHz are studied. To obtain ...diamond dielectric films with maximum resistivity the deposition of films in three gas mixtures is investigated: hydrogen-methane mixture, hydrogen-methane mixture with the addition of oxygen and hydrogen-methane mixture with the addition of an inert gas. A relationship has been established between the growth conditions, structural and electrical properties of NCD films. It is shown that for the use of NCD films as effective dielectrics preliminary high-temperature annealing of the films is required, for example, in vacuum at a temperature of 600°C for one hour.
Aim: Lung ischaemia–reperfusion induces nitric oxide synthesis and reactive nitrogen species, decreasing nitric oxide bioavailability. We hypothesized that in the ventilated lung, this process ...begins during ischaemia and intensifies with reperfusion, contributing to ischaemia–reperfusion‐induced pulmonary vasoconstriction. The aim was to determine whether ischaemia–reperfusion alters inducible and endothelial nitric oxide synthase expression/activity, reactive nitrogen species generation, and nitric oxide bioavailability, potentially affecting pulmonary perfusion.
Methods: Ischaemia–reperfusion was induced for various times in anesthetized rabbits with ventilated lungs by reversibly occluding the right pulmonary artery and initiating reperfusion. Nitric oxide synthase activity/expression and phosphorylation, reactive nitrogen species generation and total nitrate/nitrite were determined in lung tissue.
Results: Inducible nitric oxide synthase expression and activity, and reactive nitrogen species formation coincided with increased pulmonary vascular resistance during reperfusion and increased with ischaemia duration, further increasing after 2‐h reperfusion. Total nitrate/nitrite also increased with ischaemia but decreased after 2‐h reperfusion. Pre‐treatment with an inducible nitric oxide synthase inhibitor (1400W; Cayman Chemical Company, Ann Arbor, MI, USA) attenuated inducible nitric oxide synthase activity, reactive nitrogen species generation and pulmonary vascular resistance, but did not affect total nitrate/nitrite. Endothelial nitric oxide synthase expression was unchanged by ischaemia–reperfusion; however, its phosphorylation on serine 1177 and dephosphorylation on threonine 495 was uncoupled, suggesting decreased endothelial nitric oxide synthase activity. 1400W prevented uncoupling of endothelial nitric oxide synthase phosphorylation, maintaining its activity during reperfusion.
Conclusion: Ischaemia–reperfusion up‐regulates inducible nitric oxide synthesis and/activity, which coincides with reduced endothelial nitric oxide synthase activity as suggested by its uncoupling and may contribute to ischaemia–reperfusion‐induced pulmonary vasoconstriction.
The effect of preventive administration of melatonin on the arrhythmogenic substrate in the myocardium was studied in the rabbit model of acute ischemia/reperfusion
in vivo
. The animals treated with ...melatonin 60 min before ischemia induction had shorter median activation time compared to the control group (
p
=0.039), less pronounced shortening of repolarization durations in the ischemic zone during coronary occlusion (
p
=0.008), and more complete recovery of repolarization during reperfusion (
p
=0.027). In the melatonin group, the dispersion of repolarization was less than in the control group during both ischemic period (
p
=0.043) and reperfusion (
p
=0.038). Thus, preventive administration of melatonin mitigated the arrhythmogenic substrate in the heart under conditions of ischemia/reperfusion.
Diabetes mellitus (DM) increases the risk of sudden cardiac death, which suggests the involvement of arrhythmogenic mechanisms. Among other changes, DM causes cardiac autonomic neuropathy (CAN), but ...its role in electrophysiological myocardial remodeling is unclear. The objective of the present study was to test the effects of β-adrenergic blockade regarding ventricular spatiotemporal electrophysiological properties in an experimental DM model. Epicardial mapping (64-lead sock electrode array) was done in 13 control and 11 alloxan-induced DM rabbits. Activation times (AT), end of repolarization times (RT), and activation-repolarization intervals (ARI) were determined as
dV
/
dt
min during QRS,
dV
/
dt
max during T-wave, and RT-AT difference, respectively. The β-adrenergic blockade was produced by esmolol infusion (0.5 mg/kg, i.v.). It was found that the early-stage DM in rabbits was characterized by relatively mild changes in ventricular myocardium, which did not involve ventricular activation and the average duration of repolarization. The signature of this stage was the local prolongation of repolarization, which pertained to the RV apical region. The blockade of β-adrenergic receptors in healthy animals produced a ventricular spatiotemporal repolarization pattern similar to that observed in diabetic rabbits with the local apical prolongation of repolarization. On the other hand, the blockade of β-adrenergic receptors in diabetics prolonged the relatively short basal repolarization. It can be concluded that β-adrenergic blockade in healthy animals reproduced the early-stage DM effects on the spatiotemporal electrophysiological properties of the ventricular myocardium. This demonstrated the role which CAN could play in the electrical remodeling of ventricular myocardium in early-stage DM.
Dimensional effects in the magnetoresistive properties of FeхСо1 – х/Сu/FeхСо1 – х three-layer magnetically ordered films obtained by layer-by-layer metal condensation followed by heat treatment in ...the temperature range of 300÷550 K were studied experimentally and theoretically using generalized Dieny formulas 1, 2. It is shown that in the case when the cover layer thickness is much smaller (greater) than the base layer thickness, the numerical value of the ratio is negligible due to shunting of the covering layer resistance by the resistances of the base layer and the nonmagnetic layer (shunting of the resistances of the base layer and the nonmagnetic layer by the resistance of the covering magnetic layer). If the thickness of the base and cover layers are the same, the value of becomes maximum due to the absence of the shunting effect. If the thickness of the non-magnetic layer increases, provided that the thicknesses of the base and magnetic layers of the metal do not change, the ratio monotonically decreases with increasing spacer thickness.
The growth of modern wireless communications has increased the demand for high quality data services. This article presents an analysis of the performance of a DVB-S2 system with MIMO technology. A ...method for using a receiver-transmitter based on DVB-S2 with MIMO technology, provides a better quality of service for data transmission and discusses ways to improve the quality of data transmission using size and type converters of transmitting and receiving data, an amplifier and a normalizer Gain. The circuit was examined for bit error rate (BER) and peak signal-to-noise ratio (PSNR) between AWGN and multipath Rayleigh fading images operating under intersymbol interference (ZST).The analysis was carried out and a graph of the influence of ISI was obtained. The proposed system has the best quality of service for data transmission for fading channels. The transmission of images in the system includes a Rayleigh channel and AWGN with different values of the signal-to-noise ratio (SNR, dB) and different values of Gain. The Gain values change the BER and PSNR values (7.834 dB, 8.385 dB, and inf) at an SNR of -58 dB with respect to Gain values of 1, 32400 and 648000, respectively. Also obtained eye diagrams, where you can see a decrease in the negative impact of intersymbol interference with an increase in the value of Gain. .This system can be used to wirelessly transmit higher quality, high-resolution radiological images (such as computed tomography or magnetic resonance imaging) over a wireless network to remote healthcare workers.
Postoperative delirium is common in elderly patients. It increases mortality, duration of hospital stay, promotes disability, reduces the quality of life and independence. In this review, we ...summarize the scientific literature on epidemiology, assessment, pathogenesis, prophylaxis and treatment of deliriumfollowed after orthopedic surgery.
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