Concurrent engineering in designing a system for sensing gas leaks in harsh space environment

Leak monitoring is an essential operation that must be taken into consideration while making the design of a spatial vehicle. In order to make these vehicles function correctly in space and to avoid disasters, one needs to integrate multiple sensors to determine the exact concentrations of fuels such as hydrogen, hydrazine, hydrocarbon or oxygen which are frequently used while launching a space vehicle. These concentrations are important, as hydrogen-oxygen mixtures can ignite with a very small amount of energy. Moreover, it is almost impossible for people to sense the presence of hydrogen, as this gas is odorless and colorless. In the propulsion industry, hydrogen leaks generated several disasters. In 1990 such an error affected the propulsion system while workers were on the launching platform. They were forced to abort all the current processes until the source of leakage could be identified. Another example is the APOLLO 13 mission that took place in 1970 when N.A.S.A aimed to land on the Moon. Two days after the launch there has been a malfunction of the electrical system which caused an explosion leading to the loss of oxygen in both tanks. The crew used a module called lifeboat on their way back to Earth where they completed the landing. The goal of this paper is the describe the concept of an intelligent system that will monitor the presence of oxygen, hydrogen gas in harsh space environments such as vacuum, temperature variations and also beta and gamma radiations. Therefore, some aspects such as the weight of the device or environmental conditions must be taken into consideration when doing concurrent engineering. Micro and nanotechnologies allow the presence of multiple sensors without increasing the size, the weight or the energy consumption. Also, they must resist harsh conditions from space

In silico study of PEI-PEG-squalene-dsDNA polyplex formation: the delicate role of the PEG length in the binding of PEI to DNA

Using a two step simulation protocol the atomistic interactions between PEG and b-PEI and the effect of these interactions on DNA binding were determined

The role of a medium-term physical exercise program in improving cardiovascular parameters in hypertensive patients

The objective of our study was to evaluate the changes in cardiovascular parameters in patients with hypertension who completed a 3-month physical exercise program. 229 sub-jects with high normal values of blood pressure and stage 1 hypertension (group 1) and 120 patients with stage 2 hypertension (group 2) followed a 3-month physical exercise program. The following parameters were measured: systolic blood pressure, diastolic blood pressure, pulse pressure, heart rate, pulse wave velocity. For group 1 there were sta-tistically significant differences for all the tested parameters after the 3-month program (decreased systolic blood pressure, heart rate, pulse pressure and pulse wave velocity, p< 0.0001; lower diastolic blood pressure, p=0.018)). In group 2 all the tested parameters had decreased values after the 3-month rehabilitation program. However, only for the pulse wave velocity there was recorded a statistically significant reduction after the exercise program (p< 0.001). There were significant direct correlations between total cholesterol and pulse wave velocity for group 1 at both initial (p=0.024) and final assessments (p=0.03), and for group 2 patients at the 3-month assessment (p=0.001). A medium-term physical exercise program improved the cardiovascular parameters (blood pressure, arte-rial stiffness) in hypertensive patients

Molecular docking study on the potency of glycosaminoglycans (GaGs) as co-activators of fibroblasts proliferation and differentiation

Fibroblast growth factors (FGF) are heparin-binding polypeptides that control differentiation, growth and migration of many cell types. The signaling in the FGF pathway implies the dimerization of their corresponding cell surface receptors and consequently their activation through autophosphorylation of their cytoplasmatic domains. This process is modulated by heparan-sulfates (HS) or heparan-sufate-proteoglycans (HSPG) present in great abundance on cell surfaces. Different aspects of this modulation were a matter of debate in the last years in the field literature and some of them still remains unclear. The present study is trying to give some answers to a part of these problems by using quantitatively physical theoretical models of the molecules involved in these processes. We aimed to explain, through the aid of molecular docking techniques, the experimental findings about the activation of FGF receptors by small saccharides (di- and tetrasaccharides) and as a result we propose a model for this process. Also, the findings resulted from docking experiments of longer oligosaccharides (hexa- and octasaccharides) offer insights about the stoichiometry of the receptorial complex, supporting a (2:2:2)FGF:FGFR:HS ratio scheme rather than a (2:2:1)FGF:FGFR:HS one, in accordance with recent experiments on the subject published in the literature

Xanthan/chondroitin sulfate hydrogels as carrier for drug delivery applications

Preparation, characterization and in vitro release studies of codeine from xanthan/chondroitin sulfate (X/CS) hydrogels prepared through a crosslinking technique are reported. Swelling and drug delivery studies were conducted in phosphate buffer solution (pH=7.4) which simulates the pH of the intestinal fluid, at 37 °C. The in vitro release test revealed that the percentage of codeine released in phosphate buffer solution increases with increasing the amount of chondroitin sulfate in the composition of hydrogels. The drug release behaviour of the hydrogels loaded with codeine fitted well with case II transport mechanism for all formulations. The biocompatibility testing was made by hemolisys (plasma hemoglobin) technique

A semiquantitative analysis technique regarding immunohistochemical detection for matrix metalloproteinases

Modern image processing techniques are used today in order to evaluate immunohistochemical detection for various markers, especially those important for malignant tumor diagnosis and remodeling processes. Evaluating the immunohistochemical markers detection may be completed by a quantitative analysis. We have used samples of normal and fibrous tissue from surgical scars harvested after 2 months from surgery. We have investigated the immunohistochemically marked areas and we have performed a semiquantitative image analysis, using an academic, open sourcesoftware, ImageJ v. 1.38. After image adjustments (binarization) and correction, we have applied a deconvolution filter after which we have performed and analyzed a histogram of the selected area. The binarized areas were measured and compared for three samples of each tissue. We have followed the semiquantitative analysis of MMP-2 and MMP-9 presence on the investigated samples. This technique, even if controversial, allows us a fast analysis of common markers detected by immunohistochemistr

Cellulose/chondroitin sulphate hydrogels as carriers for drug delivery applications

The potential of the hydrogels based on natural, biodegradable and biocompatible polysaccharides, cellulose (C) and chondrotin sulphate (GAG), as sustained release vehicles, has been followed by in vitro swelling and drug release studies. The swelling studies were performed by mass measurements at 37 0C in twice distilled water. The release profiles and release kinetics of codeine, an opiate used for its analgesic, antitussive and antidiarrheal properties, were determined. Water-uptake data and drug release measurements are given for characterization of new solid dosage forms, the importance of the chondroitin sulphate presence being also discussed. The biocompatibility testing was made by hemolysis (plasma hemoglobin) technique. It seems that cellulose/chondroitin sulphate hydrogels are promising formulations for drug delivery

Pharmacophore identification for matrix metalloproteinases by in silico investigations

Pharmacophores are a collection of universal chemical properties that characterizes the specific action of a ligand in the active site of a three-dimensional conformational model of a molecule. Aim. To define the pharmacophores, from some MMP-inhibitor complexes, defined experimentally in protein databank. Material and methods. We have used LiganScout software that supports the pharmacophore alignment and of important ligand molecules, based on their properties, in arbitrary combinations. The alignment of the two elements is realized by pairing only regardless the number of aligned elements. We have chosen 9 files crystalographically defined as MMP-inhibitor complexes: 1eub, 1fls, 1xuc, 1xud, 1xur, 1you, 1ztq, 456c and 830c, respectively. Results and discussions. Different type of inhibitors shows different pharmacophores, with respect to Zn coordination and for the hydrophobic tunnel in the enzyme binding pocket. Conclusions: it is important to understand substrate selectivity in order to develop new synthetic MMP inhibitors. Not only the Zn ion coordination in the P site is important but also the hydrophobicity of S1 tunnel can be a step in further computer design for potent inhibitor or enzyme modulation factors

BIOCOMPATIBILITY TESTING OF CHITOSAN HYDROGELS

Chitosan is a linear, natural cationic polysaccharide comprising beta-1,4 linked glucosamine and N-acetyl-D-glucosamine. Hydrogels of chitosan were prepared by crosslinking with varying amounts of glutaraldehyde. It can be used as a bacteriostatic, fungistatic and coating agent, and the gels and suspensions may play the role of carriers for slow release or controlled delivery of drugs, as an immobilizing medium and an encapsulation material. Material and methods: Chitosan and glutaraldehyde were used to prepare the hydrogels and their characteristics were investigated by Fourier transform infrared (FT-IR) spectroscopy and the inhibitory effect on cellular growth was tested by chemiluminescence assay. The hemolytic activity was also determined by direct contact with human blood and the concentration of hemoglobin was spectrophotometrically measured. Results and discussion: Chitosan hydrogels have no inhibitory effect on cell growth, and hemolytic action below 1%, which means good blood compatibility; therefore they are promising materials