Correlation of Gas Quality with Hydrodynamic Parameters in Transmission Networks

Natural gases are a mixture of hydrocarbons. Their composition determines the basic variables that need to be taken into account in the calculation of transport or gathering systems. In the daily operation of gas gathering and transport networks, the available composition measured by online systems is reduced. In the usual composition a pseudo-component called C6+ (or C7+) is used. If this component is defined from the complete chromatograph analysis of gas, the properties are established through a lumping procedure. Online chromatographic analysis is done on a small group of basic components, usually for heavy components by introducing a pseudo-component, in this paper called C6+. In this paper we will show how to determine the properties of the pseudo-component according to the measured density of the mixture and its dynamics through the network. Generally, transport networks operators are interested in operating them so as to maximize the benefit and reduce any penalties. For this they have SCADA systems, which provide information on transport parameters and gas quality at the monitored points. The overall picture of the network and its short and medium-term evolution is achieved with a powerful simulator. Managing the gas quality from the entry points to the exit points must be made dynamically by the simulator. In this paper we will present results obtained with the ADMODUNET simulator produced by NetGas R&D based on the company’s agreement

Ceramic Composite Materials Obtained by Electron-Beam Physical Vapor Deposition Used as Thermal Barriers in the Aerospace Industry

This paper is focused on the basic properties of ceramic composite materials used as thermal barrier coatings in the aerospace industry like SiC, ZrC, ZrB2 etc., and summarizes some principal properties for thermal barrier coatings. Although the aerospace industry is mainly based on metallic materials, a more attractive approach is represented by ceramic materials that are often more resistant to corrosion, oxidation and wear having at the same time suitable thermal properties. It is known that the space environment presents extreme conditions that challenge aerospace scientists, but simultaneously, presents opportunities to produce materials that behave almost ideally in this environment. Used even today, metal-matrix composites (MMCs) have been developed since the beginning of the space era due to their high specific stiffness and low thermal expansion coefficient. These types of composites possess properties such as high-temperature resistance and high strength, and those potential benefits led to the use of MMCs for supreme space system requirements in the late 1980s. Electron beam physical vapor deposition (EB-PVD) is the technology that helps to obtain the composite materials that ultimately have optimal properties for the space environment, and ceramics that broadly meet the requirements for the space industry can be silicon carbide that has been developed as a standard material very quickly, possessing many advantages. One of the most promising ceramics for ultrahigh temperature applications could be zirconium carbide (ZrC) because of its remarkable properties and the competence to form unwilling oxide scales at high temperatures, but at the same time it is known that no material can have all the ideal properties. Another promising material in coating for components used for ultra-high temperature applications as thermal protection systems is zirconium diboride (ZrB2), due to its high melting point, high thermal conductivities, and relatively low density. Some composite ceramic materials like carbon–carbon fiber reinforced SiC, SiC-SiC, ZrC-SiC, ZrB2-SiC, etc., possessing low thermal conductivities have been used as thermal barrier coating (TBC) materials to increase turbine inlet temperatures since the 1960s. With increasing engine efficiency, they can reduce metal surface temperatures and prolong the lifetime of the hot sections of aero-engines and land-based turbines

Neurosurgical treatment of congenital arachnoids cysts in adults: 33 case series review

Authors analyze a 33 case series of adult cases operated in Clinic Emergency Hospital "Bagdasar-Arseni", Bucharest, Fourth Neurosurgical Department, for intracranial arachnoids cysts between 1996 and 2006 and selected from 186 cases diagnosed with this type of disease. The series counts 11 woman (33.33%) and 22 man (66.66%), with a medium age of 37 years, and a total follow-up time of 5.6 years. The main symptoms were headache (28 - 84%), seizures (18-54.5%), dizziness (19-57.5%), behavioral abnormality and learning difficulty or memory troubles (17-51.5%). Papiledema was present in 8 cases (2424%). In 9 cases (27.27%) a cyst-peritoneal shunt was placed, and in the other 24 cases (72.72%) was performed an open craniotomy with cyst fenestration. In both procedures the opening CSF pressure was measured, ranging from 230 to 460 mm H20. 31 patients (93.9%) improved after surgery; one remained unchanged (3.03%) and one deteriorated (3.03%). Authors analyze the outcome and symptoms on medium term and conclude that in selected cases, both neurosurgical procedures improves the patients with low risks, decreases all symptoms, and specially the frequency of seizures under minimal anti epileptic therapy. The patient prognosis is directly related with the decrease in size of the cyst, this anatomic relation being and reliable argument for active neurosurgical management.&nbsp

Synthesis and Characterization of Porous Forsterite Ceramics with Prospective Tissue Engineering Applications

Due to the urgent need to develop and improve biomaterials, the present article proposes a new strategy to obtain porous scaffolds based on forsterite (Mg2SiO4) for bone tissue regeneration. The main objective is to restore and improve bone function, providing a stable environment for regeneration. The usage of magnesium silicate relies on its mechanical properties being superior to hydroxyapatite and, in general, to calcium phosphates, as well as its high biocompatibility, and antibacterial properties. Mg2SiO4 powder was obtained using the sol-gel method, which was calcinated at 800 °C for 2 h; then, part of the powder was further used to make porous ceramics by mixing it with a porogenic agent (e.g., sucrose). The raw ceramic bodies were subjected to two sintering treatments, at 1250 or 1320 °C, and the characterization results were discussed comparatively. The porogenic agent did not influence the identified phases or the samples’ crystallinity and was efficiently removed during the heat treatment. Moreover, the effect of the porogenic agent no longer seems significant after sintering at 1250 °C; the difference in porosity between the two ceramics was negligible. When analysing the in vitro cytotoxicity of the samples, the ones that were porous and treated at 1320 °C showed slightly better cell viability, with the cells appearing to adhere more easily to their surface.</b

Alkali Niobate Powder Synthesis Using an Emerging Microwave-Assisted Hydrothermal Method

For more than five decades, alkali niobate-based materials (KxNa1&minus;xNbO3) have been one of the most promising lead-free piezoelectric materials researched to be used in electronics, photocatalysis, energy storage/conversion and medical applications, due to their important health and environmentally friendly nature. In this paper, our strategy was to synthetize the nearest reproductible composition to KxNa1&minus;xNbO3 (KNN) with x = 0.5, placed at the limit of the morphotropic phase boundary (MPB) with the presence of both polymorphic phases, orthorhombic and tetragonal. The wet synthesis route was chosen to make the mix crystal powders, starting with the suspension preparation of Nb2O5 powder and KOH and NaOH alkaline solutions. Hydrothermal microwave-assisted maturation (HTMW), following the parameter variation T = 200&ndash;250 &deg;C, p = 47&ndash;60 bar and dwelling time of 30&ndash;90 min, was performed. All powders therefore synthesized were entirely KxN1&minus;xNbO3 solid solutions with x = 0.06&ndash;0.69, and the compositional, elemental, structural and morphological characterization highlighted polycrystalline particle assemblage with cubic and prismatic morphology, with sizes between 0.28 nm and 2.95 &mu;m and polymorphic O-T phase coexistence, and a d33 piezoelectric constant under 1 pC/N of the compacted unsintered and unpoled discs were found

Thermally Activated Al(OH)3 Part II—Effect of Different Thermal Treatments

In this paper, the thermal decomposition of crystalline Al(OH)3 was studied over the temperature range of 260–400 °C for particles with a size between 10 and 150 µm. The weight losses and thermal effects occurring in each of the dehydration process were assessed using thermogravimetry (TG) and differential scanning calorimetry (DSC) thermal analysis. X-ray diffraction (XRD) patterns, refined by the Rietveld method, were used for mineral phase identification, phase composition analysis, and crystallinity degree determination. Moreover, the particle size distributions and their corresponding D10, D50, and D90 numeric values were determined with a laser analyzer. We observed a strong relationship between the calcination temperature, the initial gibbsite grade particle size, and the crystallinity of the resulting powders. Hence, for all endothermic effects identified by DSC, the associated temperature values significantly decreased insofar as the particle dimensions decreased. When the gibbsite was calcined at a low temperature, we identified small amounts of boehmite phase along with amorphous new phases and unconverted gibbsite, while the powders calcined at 400 °C gradually yielded a mixture of boehmite and crystalized γ-Al2O3. The crystallinity % of all phase transition products declined with the increase in particle size or temperature for all the samples

Biomimetic Composite Scaffold Based on Naturally Derived Biomaterials

This paper proposes the development of a biomimetic composite based on naturally derived biomaterials. This freeze-dried scaffold contains a microwave-synthesized form of biomimetic hydroxyapatite (HAp), using the interwoven hierarchical structure of eggshell membrane (ESM) as bio-template. The bone regeneration capacity of the scaffold is enhanced with the help of added tricalcium phosphate from bovine Bone ash (BA). With the addition of Gelatin (Gel) and Chitosan (CS) as organic matrix, the obtained composite is characterized by the ability to stimulate the cellular response and might accelerate the bone healing process. Structural characterization of the synthesized HAp (ESM) confirms the presence of both hydroxyapatite and monetite phases, in accordance with the spectroscopy results on the ESM before and after the microwave thermal treatment (the presence of phosphate group). Morphology studies on all individual components and final scaffold, highlight their morphology and porous structure, characteristics that influence the biocompatibility of the scaffold. Porosity, swelling rate and the in vitro cytotoxicity assays performed on amniotic fluid stem cells (AFSC), demonstrate the effective biocompatibility of the obtained materials. The experimental results presented in this paper highlight an original biocomposite scaffold obtained from naturally derived materials, in a nontoxic manner

Multifunctional Platforms Based on Graphene Oxide and Natural Products

Background and objectives: In the last few years, graphene oxide has attracted much attention in biomedical applications due to its unique physico-chemical properties and can be used as a carrier for both hydrophilic and/or hydrophobic biomolecules. The purpose of this paper was to synthesize graphene oxide and to obtain multifunctional platforms based on graphene oxide as a nanocarrier loaded with few biologically active substances with anticancer, antimicrobial or anti-inflammatory properties such as gallic acid, caffeic acid, limonene and nutmeg and cembra pine essential oils. Materials and Methods: Graphene oxide was obtained according to the method developed by Hummers and further loaded with biologically active agents. The obtained platforms were characterized using FTIR, HPLC, TGA, SEM, TEM and Raman spectroscopy. Results: Gallic acid released 80% within 10 days but all the other biologically active agents did not release because their affinity for the graphene oxide support was higher than that of the phosphate buffer solution. SEM characterization showed the formation of nanosheets and a slight increase in the degree of agglomeration of the particles. The ratio I2D/IG for all samples was between 0.18 for GO-cembra pine and 0.27 for GO-limonene, indicating that the GO materials were in the form of multilayers. The individual GO sheets were found to have less than 20 &#181;m, the thickness of GO was estimated to be ~4 nm and an interlayer spacing of about 2.12 &#197;. Raman spectroscopy indicated that the bioactive substances were adsorbed on the surface and no degradation occurred during loading. Conclusions: These findings encourage this research to further explore, both in vitro and in vivo, the biological activities of bioactive agents for their use in medicine

Multiple intracranial meningiomas with different pathological subtype

Authors present the case of a 63 years old woman, admitted for left proptosis and hemicrania evolving for three months. At the screening CT scan with contrast were discovered two lesions: a left fronto-temporal mass, intensely contrast enhancing, with peritumoral edema, inserted on the sphenoid wing, extended in the infratemporal fossa and ethmoidal sinus; the other lesion was cystic, located parieto-temporally, in the corticosubcortical area, with a small tumor nodule located deeply. MRI defined the details and the size of the lesions: 63/65/71 mm left solid tumor suggesting a sphenoid wing meningioma, and a 67/62/72 mm right parietal-temporal cystic lesion with moderate mass effect. Authors insist on neurosurgical strategy for treatment of multiple intracranial masses with different consistency-solid and cystic. Adequate surgical planning was done after MRI with contrast examinations, which were strongly suggestive for multiple intracranial meningiomas. Surgical approach was done in two steps according to treat first the cystic lesion because we supposed that is a recent developed lesion with high risk of sudden volume increase followed by neurological deterioration. On another way, attacking first the solid tumor, we could have a high risk to decompensate the cystic lesion. Neurological and general evolution after two steps neurosurgery was without incidents with a very good outcome. Pathological examination revealed two different types of meningioma: microcystic and transitional

Biocompatible Ag/Fe-Enhanced TiO2 Nanoparticles as an Effective Compound in Sunscreens

In this work, valuable biocompatible Ag/Fe-enhanced TiO2 nanoparticles are comparatively prepared by a conventional wet chemistry method (sol-gel) and a rapid, efficient, hybrid unconventional method (microwave-assisted hydrothermal synthesis). In order to establish their application as effective compounds in sunscreens, the obtained powders were first structurally and morphologically characterized, analyses from which their nanodimensional character, crystalline structure and thermal behavior were highlighted. The evaluation of sunscreen effectiveness is based on the determination of the sun protection factor (SPF). It was observed that silver enhancing increases the SPF significantly, especially when compared to the pristine samples. The obtained Ag/Fe-enhanced TiO2 powders were also evaluated from the point of view of their biocompatibility on amniotic fluid stem cells, and the results indicated an enhance of cell proliferation when exposed to the synthesized nanostructures