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Publicatii proprii
RIETVELD REFINEMENT OF POWDER X-RAY DIFFRACTION OF NANOCRYSTALLINE NOBLE METALS – TUNGSTEN TRIOXIDE
Tungsten trioxide powders were prepared from peroxo-tungstic acid (PTA) precursor obtained by sol-gel route, in aqueous medium. Two WO 3 samples were doped with noble metals, by "loading" them with silver and metallic palladium. The unit cell parameters of the WO 3 monoclinic phase, the effective crystallite mean size, D eff (nm), and the mean root mean square (rms) of the microstrains , 1/2 hkl ,were calculated by Rietveld refinement analysis. The
Read moreOCT4: Dynamic DNA binding pioneers stem cell pluripotency
OCT4 was discovered more than two decades ago as a transcription factor specific to early embryonic development. Early studies with OCT4 were descriptive and looked at determining the functional roles of OCT4 in the embryo as well as in pluripotent cell lines derived from embryos. Later studies showed that OCT4 was one of the transcription factors in the four-factor cocktail required for reprogramming somatic cells into induced pluripotent stem cells
Read moreEstudio de las tensiones en válvulas biplanas tipo mariposa
This paper presents the study of tensions developed as a result of the static actuation developed in a biplane valve, butterfly type, with a 1.500 mm diameter, loaded with a pressure of 1 MPa, using the finite element method, experimentally verified using a resistive electrical tensiometrical method. The proper knowledge of those valve types is very important in order to control the admissible losses.
Read moreTechnological aspects of assembling and processing narrow tubes
The paper presents the assembling, welding and processing of narrow tubes made of austenitic stainless steel used for the manufacturing of syringes and of food industry parts. At the same time, the paper discusses the various phenomena occurring during the processing of the materials previous to assembling and welding as well as during the welding operation proper. Following these studies and experiments, a suitable welding technology has been homologated
Read moreStudy of the materials used in the manufacturing of a tubular camshaft
In this workshop we elaborated several heat treatment tests to a large number of cams in order to achieve better results of mechanical resistance of a tubular camshaft made for an internal combustion engine. The most important results of our tests are represented in a few graphics and tables in this workshop
Read moreThe influence of the braking time on heat flow through the friction surfaces of the friction elements of disk brakes for railway vehicles
Disk brakes were first introduced on the suburban and urban coaches and high speed freight cars (V > 120 km/h) for the following reasons: shoe brakes reached their potential limits, especially at high speeds; the maintenance of disc brakes is cheaper; greater comfort; the friction coefficient of disk brake elements (friction pad and brake disc) presents lower variation in velocity and pressure; disk brakes present lower temperatures of friction surfaces.
Read moreMathematical model of three-phase induction machine connected to advanced inverter for traction system for electric trolley
This paper establishes a mathematical model of induction machine connected to a frequency inverter necessary to adjust the electric motor drive. The mathematical model based on the Park’s theory allows the analysis of the whole spectrum (electric car – frequency inverter) to drive the electric trolley bus made on ASTRA Bus Arad (Romania). To remove higher order harmonics, the PWM waveform of supply voltage is used, set in the general case. Operating
Read moreStructural properties of some transition metal highly doped carbon aerogels
Structural characterization of transition metal highly doped carbon aerogels obtained through the sol–gel polymerization process of the formaldehyde with the potassium salt of 2,4-dihydroxybenzoic acid, followed by metal ions exchange using Ni(II) and Cu(II) aqueous solutions, supercritical drying with liquid CO2 and carbonization at 1050 °C under inert atmosphere has been performed. Transmission electron microscopy (TEM), X-ray diffraction (XRD)
Read moreStructural and Transport Properties of Hg1-xCdxTe/CdTe Semiconductor Heterostructures
Structural and Transport Properties of Hg1-xCdxTe/CdTe Semiconductor Heterostructures
Read moreSynthesis and characterisation of rare earth oxysulphide phosphors. I. Studies on the preparation of Gd 2O 2S:Tb phosphor by the flux method
Terbium activated gadolinium oxysulphide phosphor (Gd2O2S:Tb) shows bright green luminescence and high efficiency under X-ray excitation. Phosphor utilisation depends on powder characteristics and luminescence properties that are regulated during the synthesis stage. The paper presents some of our new results on the synthesis of Gd2O2S:Tb phosphor by solid-state reaction route from oxide precursors. Efficient luminescent powders utilisable in the
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