Antioxidant and Protective Mechanisms against Hypoxia and Hypoglycaemia in Cortical Neurons in Vitro

In the present work, we have studied whether cell death could be induced in cortical neurons from rats subjected to different period of O₂ deprivation and low glucose (ODLG). This “in vitro” model is designed to emulate the penumbra area under ischemia. In these conditions, cortical neurons displayed loss of mitochondrial respiratory ability however, nor necrosis neither apoptosis occurred despite ROS production. The absence of cellular death could be a consequence of increased antioxidant responses such as superoxide dismutase-1 (SOD1) and GPX3. In addition, the levels of reduced glutathione were augmented and HIF-1/3α overexpressed. After long periods of ODLG (12–24 h) cortical neurons showed cellular and mitochondrial membrane alterations and did not recuperate cellular viability during reperfusion. This could mean that therapies directed toward prevention of cellular and mitochondrial membrane imbalance or cell death through mechanisms other than necrosis or apoptosis, like authophagy, may be a way to prevent ODLG damage.     

Uncertainty determination methodology, sampling maps generation and trend studies with biomass thermogravimetric analysis

This paper investigates a method for the determination of the maximum sampling error and confidence intervals of thermal properties obtained from thermogravimetric analysis (TG analysis) for several lignocellulosic materials (ground olive stone, almond shell, pine pellets and oak pellets), completing previous work of the same authors. A comparison has been made between results of TG analysis and prompt analysis. Levels of uncertainty and errors were obtained, demonstrating that properties evaluated by TG analysis were representative of the overall fuel composition, and no correlation between prompt and TG analysis exists. Additionally, a study of trends and time correlations is indicated. These results are particularly interesting for biomass energy applications.     

Comparison of atrial signal extraction algorithms in 12-lead ECGs with atrial fibrillation

Analysis of atrial rhythm is important in the treatment and management of patients with atrial fibrillation. Several algorithms exist for extracting the atrial signal from the electrocardiogram (ECG) in atrial fibrillation, but there are few reports on how well these techniques are able to recover the atrial signal. We assessed and compared three algorithms for extracting the atrial signal from the 12-lead ECG. The 12-lead ECGs of 30 patients in atrial fibrillation were analyzed. Atrial activity was extracted by three algorithms, Spatiotemporal QRST cancellation (STC), principal component analysis (PCA), and independent component analysis (ICA). The amplitude and frequency characteristics of the extracted atrial signals were compared between algorithms and against reference data. Mean (standard deviation) amplitude of QRST segments of V1 was 0.99 (0.54) mV, compared to 0.18 (0.11) mV (STC), 0.19 (0.13) mV (PCA), and 0.29 (0.22) mV (ICA). Hence, for all algorithms there were significant reductions in the amplitude of the ventricular activity compared with that in V1. Reference atrial signal amplitude in V1 was 0.18 (0.11) mV, compared to 0.17 (0.10) mV (STC), 0.12 (0.09) mV (PCA), and 0.18 (0.13) mV (ICA) in the extracted atrial signals. PCA tended to attenuate the atrial signal in these segments. There were no significant differences for any of the algorithms when comparing the amplitude of the reference atrial signal with that of the extracted atrial signals in segments in which ventricular activity had been removed. There were no significant differences between algorithms in the frequency characteristics of the extracted atrial signals. There were discrepancies in amplitude and frequency characteristics of the atrial signal in only a few cases resulting from notable residual ventricular activity for PCA and ICA algorithms. In conclusion, the extracted atrial signals from these algorithms exhibit very similar amplitude and frequency characteristics. Users of these algorithms should be observant of residual ventricular activities which can affect the analysis of the fibrillatory waveform in clinical practice.     

Application of formal languages in polynomial transformations of instances between NP-complete problems

We propose the usage of formal languages for expressing instances of NP-complete problems for their application in polynomial transformations. The proposed approach, which consists of using formal language theory for polynomial transformations, is more robust, more practical, and faster to apply to real problems than the theory of polynomial transformations. In this paper we propose a methodology for transforming instances between NP-complete problems, which differs from Garey and Johnson’s. Unlike most transformations which are used for proving that a problem is NP-complete based on the NP-completeness of another problem, the proposed approach is intended for extrapolating some known characteristics, phenomena, or behaviors from a problem A to another problem B. This extrapolation could be useful for predicting the performance of an algorithm for solving B based on its known performance for problem A, or for taking an algorithm that solves A and adapting it to solve B.     

A GRASP approach for the extended car sequencing problem

This paper presents a solution procedure for a new variant of the Car Sequencing Problem (CSP) based on the GRASP metaheuristic. In this variant, called xCSP (extended CSP), the aim is to satisfy the hard constraints of the CSP while scheduling the maximum possible number of cars with specific options at specific times of the day in order to satisfy other production requirements. Additional constraint ratios are likewise considered that force at least a minimum specific number of consecutive options. An extension of the CSP is formalized in this paper and computational results are presented using available on-line instances that verify the good performance of a GRASP procedure defined for the xCSP.     

Physical and mechanical properties of unsaturated polyester resin matrix from recycled PET (based PG) with corn straw fiber

In this study, composites of unsaturated polyester resin (UPR), synthesized from recycled polyethylene terephthalate (PET), with 10 to 40% in volume of corn straw fiber (CSF), were elaborated and studied the effect of fiber content on their physical and mechanical properties. The content of cellulose (48.97%), hemicellulose (24.06%), and lignin (6.59%) were determined by chemical characterization of CSF. The characteristic bonds of the UPR were identified as a cross-linking network between the styrene monomer (ST) and the unsaturated polyester (UP) through FTIR. Two decomposition stages were observed by TGA–DTG. The results of physical and mechanical properties showed that as the fiber content increased in the UPR, the water absorption increased (0.6% to 2.56%), on the other hand, the density (1218.23 to 1150.28 kg/m³), flexural strength (50.58 to 26.98 MPa), flexural modulus (2.66 to 2.29 GPa), tensile strength (8.62 to 3.65 MPa), tensile modulus (1.18 to 0.43 GPa), and hardness (81.67 to 65.67 Shore D), they decreased. SEM analysis showed some defects in the fiber distribution in the UPR, which affected the mechanical properties of the composites. This research contributes to the development of new material from use of two waste materials for the benefit of the environment.     

The effect of silk fibroin nanoparticles on the morphology,rheology, dynamic mechanical properties,and toughness of poly(lactic acid)/poly(ε-caprolactone) nanocomposite

The silk fibroin nanoparticles (SFNPs) were extracted from silkworm cocoons and used as a nanofiller in poly(lactic acid) (PLA)/poly(ε-caprolactone) (PCL) blend. The nanoparticle localization was studied theoretically and experimentally and the effects of SFNP on the morphology, rheology, toughness, and dynamic mechanical properties of the blend were investigated. According to the calculated wetting coefficient, SFNP should be thermodynamically located in the PLA matrix during the melting process. The results of SEM illustrated a common sea-island structure for the PLA/PCL blend and the incorporation of SFNP reduced the PCL domain sizes from 1.170 ± 92 μm to 794 ± 46 nm. The atomic force microscopy results showed that the nanoparticles are mainly located in the PLA matrix and also, partially at the phase interface with a thickness of layers around 80 nm. The rheological tests displayed the network formation of SFNP in the prepared nanocomposites. The dynamic mechanical analysis revealed that by the addition of SFNP, the storage modulus of neat PLA and PLA/PCL blend were increased by around 57 and 50%, respectively and the glass transition temperatures (Tg) values of PLA and PCL shifted toward each other. Additionally, using SFNP caused a lower water uptake and higher impact strength (~64%) of the blend.     

Nonlinear regulation of a Lorenz system by feedback linearization techniques

In this paper we analyze some dynamical properties of a chaotic Lorenz system driven by a control input. These properties are the input-state and the input-output feedback linearizability, the stability of the zero dynamics, and the phase minimality of the system. We show that the controlled Lorenz system is feedback equivalent to a controllable linear system. We also show that the zero dynamics are asymptotically stable when the output is an arbitrary state. These facts allow designing control laws such that the closed-loop system has asymptotically stable equilibrium points with dynamic behavior free from chaotic transients. The controllers are robust in the sense that the closed-loop system is stable and non chaotic around a nominal set of parameter values. The results also show that the proposed controllers give better responses compared to linear algorithms obtained from standard linearization techniques, and exhibit a good performance even when the control input is bounded.