Vibrations of water hydraulic systems – an experimental approach

This paper presents an experimental study of the vibrations induced both by cavitating and by non-cavitating flow in a hydraulic installation that comprises the main elements of a water hydraulic system. The cavitation was triggered by progressively closing a butterfly valve. The vibrations were measured on the pump, on the bearings housing, on the pump drive motor, and at nine measurement points located upstream and downstream of the main elements of the installation. The measurements were carried out at different flow rates obtained at different openings of the butterfly valve. The results suggest that the phenomena that take place inside the pump and inside the bearings cause vibrations having frequencies of up to 10 kHz. The results also indicate that the cavitation that occurs at the butterfly valve causes vibrations of high frequency, above 3 kHz, that have a distinct peak at about 18 kHz. These results could be useful in establishing proper maintenance plans for hydraulic installations

Use of some natural supports for the adsorption of theophylline from aqueous solutions

In this work, the interaction of Theophylline with lemon peel and olive leaves (two natural solid supports) was studied at 25, 35 and 45 oC in order to identify the most appropriate theoretical adsorption model, as well as the corresponding thermodynamic parameters (free energy of Gibbs, enthalpy and entropy) of the adsorption process. In the first stage, the time necessary for attaining the equilibrium was established in a series of preliminary experiments, which indicated periods of time ranging from 182 to 356 minutes. The experimental data obtained from the adsorption process was fitted to the Freundlich and Langmuir classical adsorption models by linear regression analysis. The obtained results indicate that for both studied systems, the Langmuir model described better the interaction of Theophylline with the solid supports taken in work

Theoretical consideration regarding the contaminated soil

This artice represent a small review of the main methods for decontamination of soil infected with toxic chemicals. Are presented several methods such as: isolation of contaminated area, separation methods, electrochemical methods, phytoremediation and photocatalytic remediation of soil contaminated with toxic chemicals

TLC-Densitometric investigation of bioactive components from Mediterranean algae

Several photosynthetic pigments from two algae, namely Padina pavonica and Codium fragile, were extracted in different solvents and subsequently analyzed through TLC. The optimization of the separation parameters led to the choosing of the optimum eluent (hexane/acetone mixture) for polar silica gel plates. The isolated compounds were evaluated through densitometric measurements and by the acquisition of their UV-Vis spectra. While xanthophylls, chlorophyll a and pheophytin a were the most typical pigments of Padina pavonica, chlorophyll a and b, xanthophyll and β-carotene were the most characteristic pigments for Codium fragile

Characterization by soft ionization mass spectrometry methods of mono- and oligosaccharides functionalized at the anomeric center

In order to obtain oligosaccharides functionalized with amine groups, aliphatic diamines and polyamines were coupled with maltose by using reductive amination reactions. The synthesized compounds were characterized through electrospray ionization mass spectrometry (ESI-MS), while finer structural details were obtained by using MS

Preliminary TLC studies on Posidonia oceanica seagrass

Several photosynthetic pigments, i.e. chlorophylls and carotenoids, belonging to Posidonia oceanica seagrass, were separated by thin-layer chromatography (TLC) using a hexane/acetone solvent mixture. Additionally, densitometric measurements and spectral scanning of the TLC plates were performed using the Camag TLC Scanner 3 together with the WinCATS software

Reducing Friction in Orthodontic Brackets: A Matter of Material or Type of Ligation Selection? In-Vitro Comparative Study

(1) Background: Orthodontic appliances have changed and improved with the increasing demand for orthodontic treatment of the general population. Patients desire for shorter orthodontic treatments and for the wearing of more aesthetic devices has led to the technological development of orthodontic brackets; these were manufactured from aesthetic materials (ceramics, composite polymers) and presented different designs regarding the way archwires are ligated to the bracket. The aim of this study was to determine whether there were any differences between the static frictional forces generated by stainless steel (metallic) and polycrystalline alumina (ceramics) conventional and self-ligating brackets. (2) Methods: Static friction assessment was carried out in vitro with a universal testing machine, HV-500N-S (Schmidt Control Instruments, Hans Schmidt & Co. GmbH), intended for measuring compression and traction forces. (3) Results: The study revealed significant differences in static frictional forces at the bracket-archwire interface between the tested brackets. Stainless steel brackets produced lower static friction forces than polycrystalline alumina and self-ligating brackets generally produced lower static frictional forces than conventional brackets. The reduction of frictional forces was noticeable in the first stages of treatment, when thin, flexible orthodontic archwires (0.016” NiTi) are used. Engaged with large rectangular stainless steel archwires, (0.019 × 0.025” SS), the frictional forces produced by conventional and self-ligating metal brackets were similar, no significant differences being observed between the two types of metallic design. However, in the case of tested ceramic brackets, the results showed that the self-ligating type allows a reduction in frictional forces even in advanced stages of treatment compared to conventionally ligation. (4) Conclusions: From the perspective of an orthodontic system with low frictional forces, metal brackets are preferable to aesthetic ones, and self-ligating ceramic brackets are preferable to conventional ceramic brackets

The Efficiency and Safety of Leuphasyl—A Botox-Like Peptide

Peptides of synthesis are a very new strategy in cosmetic science and technology for at least two reasons: (1) they are small molecules, easily penetrable in the skin and (2) they are able to induce a very specific action, because all skin cells (keratinocytes, fibroblasts, nervous cells) have membrane receptors for peptides. This group of cosmeceutics includes the botox-like peptides, represented by acetyl hexapeptide 3 (Argireline) and pentapeptid-3 (Leuphasyl). The latter is less known and has been less studied. This substance inhibits the neuromuscular synapses in the mimic muscles, acting as enkephalins. It links the enkephalin receptor to nervous cells, thereby modulating the release of acetylcholine in synaptic space. This cellular activity will be translated in vivo in a relaxation of the muscle and a reduction of expression wrinkles. The aim of our study is to evaluate the optimal concentration of Leuphasyl for skin application at the mimic muscle level, the efficiency and the safety of this peptide. We formulated three emulsions of different concentrations (0.5%, 1%, 2%) which were applied to the skin, at the level of mimic muscles (1) at the eyebrows zone (above the corrugator supercilii muscle) and (2) at the periorbital zone (above the orbicularis oculi muscle). We evaluated the regression of the wrinkles between the eyebrows using an imagistic method: pro-derm Analyser. The study is of interest to discussions concerning how to apply these kinds of cosmetic products at the mimic muscle skin level and not at the level of the wrinkles

ROOT PERFORATIONS IN ENDODONTICALLY-TREATED POSTERIOR TEETH: A CONE-BEAM COMPUTED TOMOGRAPHY STUDY

Root perforations represent artificial communication between the endodontic system and the periodontal space or the oral cavity. While it is true that they can reduce the success rates of endodontic treatment in the long term, nevertheless, with the new bioceramic materials, the evolution is promising. The aim of this retrospective study was to assess the prevalence of perforations in root canal-treated maxillary and mandibular posterior teeth based on findings from images taken using cone-beam computed tomography (CBCT) and to review the most predictable, appropriate non-surgical treatment procedures for the clinical management of these conditions, highlighting some relevant clinical cases of complex oral rehabilitation