The objective of the work is to determine the influence of the PLA melting temperature during 3D printing on the dimensional accuracy of the model parts. Two modular drilling devices were also made using PLA model par...The objective of the work is to determine the influence of the PLA melting temperature during 3D printing on the dimensional accuracy of the model parts. Two modular drilling devices were also made using PLA model parts. The model parts were 3D printed using FDM technology and the ZMorph 2.0 hybrid 3D printer. The accuracy of 3D printing of the model part influences the realization of modular devices. In recent years, technology has evolved a lot, and the need to have the most efficient manufacturing equipment has increased. This is the reason for the development of 3D printers using FDM technology for plastic parts. The software used by these 3D printers used in FDM technology is very sophisticated, as they allow the manufacture of very precise 3D prototypes, identical to the designed 3D model, through modern additive manufacturing techniques. The quality and mechanical strength of the prototypes obtained using 3D printers is very good. The materials used by the 3D printers manufactured by FDM are cheap and accessible. These 3D printers are used to make three-dimensional objects (gears, flanges, bearings, covers, casings, mechanisms, figurines, interior and exterior design elements, architectural models, medical models).展开更多
The temperature dependences of the dynamic-elastic and viscous susceptibilities have been measured for Au83Fe17, after cold-rolling. It is found that cold-rolling reduces the Curie temperature and raises the spin-free...The temperature dependences of the dynamic-elastic and viscous susceptibilities have been measured for Au83Fe17, after cold-rolling. It is found that cold-rolling reduces the Curie temperature and raises the spin-freezing temperature remarkably. These results can be explained on the basis of the precipitation medal proposed by Borg and Violet.展开更多
The procedure by means of which the occurrence time of an impending mainshock can be identified by analyzing in natural time the seismicity in the candidate area subsequent to the recording of a precursory seismic ele...The procedure by means of which the occurrence time of an impending mainshock can be identified by analyzing in natural time the seismicity in the candidate area subsequent to the recording of a precursory seismic electric signals（SES） activity is reviewed. Here, we report the application of this procedure to an MW5.4 mainshock that occurred in Greece on 17 November 2014. This mainshock（which is pretty rare since it is the strongest in that area for more than half a century） was preceded by an SES activity recorded on 27 July 2014, and the results of the natural time analysis reveal that the system approached the critical point（mainshock occurrence） early in the morning on 15 November 2014.展开更多
The effect of H2O and the slow thermal annealing on the properties of pure silica (SiO2) and phosphosilicate (SiO2-P2O5) gel-glasses are presented. The monolithic samples have been prepared via sol-gel process using t...The effect of H2O and the slow thermal annealing on the properties of pure silica (SiO2) and phosphosilicate (SiO2-P2O5) gel-glasses are presented. The monolithic samples have been prepared via sol-gel process using tetraethorthosilicate (TEOS), Si(C2H5O)4 and Triethylphosphate (TEP) (C2H5O)3P(O) as SiO2 and P2O5 precursors. Phosphate incorporates into the silicate network by substituting Si atoms and consequently, we observed changes in structural and spectroscopic properties for these systems. The structures of prepared samples were examined by observed weight loss, XRD and FTIR. It has been found that in the structure of pure silica and phosphosilicate glasses there are formed domains characterized by certain degree of ordering of the units present in their composition, while the structure of pure silica is still amorphous of these glasses. The changing character of domains structure may be the reason of different chemical activities of phosphosilicate glass.展开更多
Several bacterial strains of Actinomycetes belonging to Streptomyces and Arthrobacter genera for the first time were used to study the biotechnology of synthesis of gold and silver nanoparticles. The experimental cond...Several bacterial strains of Actinomycetes belonging to Streptomyces and Arthrobacter genera for the first time were used to study the biotechnology of synthesis of gold and silver nanoparticles. The experimental conditions of gold and silver nanoparticles production by the cells of studied strains in aqueous chloroauric acid （HAuCIq） and in silver nitrate （AgNO3） solutions, respectively, were determined. Concentration and time-dependences of nanoparticle formation were investigated. The complex of optical and analytical methods was used for testing the gold and silver nanoparticles in the bacterial biomass. The TEM （Transmission Electron Microscopy） and XRD （X-ray Diffraction） data in all cases demonstrated the presence of crystals with fcc （face centered cubic） structure. The results obtained show that the Actinomycetes are capable of producing gold and silver nanoparticles of spherical shape extracellularly when exposed to suitable compounds. The particle size distribution shows that the sizes of nanoparticles are in the range of 5 nm to 80 nm. The biomass obtained may be used for industrial as well as medical and pharmaceutical purposes.展开更多
The results of optical investigation of hydrogenated epitaxial bilayer graphene are presented. A softening and an increase of the intensity of the in-plane anti-symmetric phonon mode are observed at 0.2eV. It is sugge...The results of optical investigation of hydrogenated epitaxial bilayer graphene are presented. A softening and an increase of the intensity of the in-plane anti-symmetric phonon mode are observed at 0.2eV. It is suggested that they both originate from coupling of the optically active phonon mode to virtual electronic transitions, which is related to the band structure of bilayer graphene and leads to the “charged phonon” effect. In addition, it is noted that optically active phonon peaks have pronounced Fano shapelines. It is argued that the Fano shapeline is attributed to the interaction of the phonon mode with a continuum of electronic transitions in valence bands of hydrogenated bilayer graphene.展开更多
In this paper,the flux pinning effects in Y_(1-x)M_(x)Ba_(2)Cu_(3)O_(7-δ)(M=Gd,Eu and Sm)samples are reported.It is found that there is another pinning mechanism under higher magnetic fields in addition to that under...In this paper,the flux pinning effects in Y_(1-x)M_(x)Ba_(2)Cu_(3)O_(7-δ)(M=Gd,Eu and Sm)samples are reported.It is found that there is another pinning mechanism under higher magnetic fields in addition to that under lower fields.This pinning effect may stem from the lattice stress field resulting from the partial substitution of the rare earth elements with different atomic radii for Y.展开更多
Nano-composite monolith and thin film Alumina-Phospho-Silicates (SiO<sub>2</sub>-P<sub>2</sub>O<sub>5</sub>-Al<sub>2</sub>O<sub>3</sub>):Ln (Ln = Sm, Er, Yb)...Nano-composite monolith and thin film Alumina-Phospho-Silicates (SiO<sub>2</sub>-P<sub>2</sub>O<sub>5</sub>-Al<sub>2</sub>O<sub>3</sub>):Ln (Ln = Sm, Er, Yb) glasses activated by triply doped with three different rare earth ions (REIs) (Er<sup>3+</sup>:Yb<sup>3+</sup>:Sm<sup>3+</sup>) were prepared by modified sol-gel process. The composition of the prepared samples was as follow (SiO<sub>2</sub>:11P<sub>2</sub>O<sub>5</sub>:3Al<sub>2</sub>O<sub>3</sub>:1.2Er<sub>2</sub>O<sub>3</sub>:(1.2 - 3)Yb<sub>2</sub>O<sub>3</sub>:(0.7 - 1.3)Sm<sub>2</sub>O<sub>3</sub>). Tetra-ethyl-orthosilicate (TEOS), tri-ethyl-phosphate (TEP), erbium nitrate, ytterbium nitrate and samarium nitrate were used as precursor materials, respectively. The structure of the prepared samples was studied using X-ray diffraction (XRD), which revealed that the crystallite sizes of monolith and thin film samples both sintered at 900℃ at constant Sm<sup>3+</sup> concentration at 1.3 mol% (SPAE<sub>1.2</sub>Y<sub>1.8</sub>S<sub>1.3</sub>) have the following values 44 and 31 nm, respectively. Transmission Electron Microscopy (TEM) of the same prepared samples was used to confirm the presence of nano-structure phase. The photo-luminescence study will be evaluated for the prepared.展开更多
The interaction between graphene and germanium surfaces was investigated using a combination of microscopic and macroscopic experimental techniques and complementary theoretical calculations.Density functional theory ...The interaction between graphene and germanium surfaces was investigated using a combination of microscopic and macroscopic experimental techniques and complementary theoretical calculations.Density functional theory （DFT） calculations for different reconstructions of the Ge（001） surface showed that the interactions between graphene and the Ge（001） surface introduce additional peaks in the density of states,superimposed on the graphene valence and conduction energy bands.The growth of graphene induces nanofaceting of the Ge（001） surface,which exhibits well-organized hill and valley structures.The graphene regions covered by hills are of high quality and exhibit an almost linear dispersion relation,which indicates weak graphene-germanium interactions.On the other hand,the graphene component occupying valley regions is significantly perturbed by the interaction with germanium.It was also found that the stronger graphene-germanium interaction observed in the valley regions is connected with a lower local electrical conductivity.Annealing of graphene/Ge（001）/Si（001） was performed to obtain a more uniform surface.This process results in a surface characterized by negligible hill and valley structures;however,the graphene properties unexpectedly deteriorated with increasing uniformity of the Ge（001） surface.To sum up,it was shown that the mechanism responsible for the formation of local conductivity inhomogeneities in graphene covering the Ge（001） surface is related to the different strength of graphene-germanium interactions.The present results indicate that,in order to obtain high-quality graphene,the experimental efforts should focus on limiting the interactions between germanium and graphene,which can be achieved by adjusting the growth conditions.展开更多
The development of micromechanical devices(MEMS and NEMS)on the basis of nanostructured shape memory alloys is reported.A Ti_(50)Ni_(25)Cu_(25)(at.%)alloy fabricated by the melt spinning technique in the form of a rib...The development of micromechanical devices(MEMS and NEMS)on the basis of nanostructured shape memory alloys is reported.A Ti_(50)Ni_(25)Cu_(25)(at.%)alloy fabricated by the melt spinning technique in the form of a ribbon with a thickness around 40µm and a width about 1.5 mm was chosen as a starting material.Technological parameters were optimized to produce the alloy in an amorphous state.The thickness of the ribbon was reduced to 5–14µm by means of electrochemical polishing.A nanostructural state of the thin ribbons was obtained via the dynamic crystallization of the amorphous alloy by application of a single electric pulse with duration in the range of 300–900µs.A microtweezers prototype with a composite cantilever of 0.8µm thick and 8µm long was developed and produced on the basis of the obtained nanostructured thin ribbons by means of the focused ion beam technique.Controlled deformation of the micromanipulator was achieved by heating using semiconductor laser radiation in a vacuum chamber of scanning ion-probe microscope.展开更多
文摘The objective of the work is to determine the influence of the PLA melting temperature during 3D printing on the dimensional accuracy of the model parts. Two modular drilling devices were also made using PLA model parts. The model parts were 3D printed using FDM technology and the ZMorph 2.0 hybrid 3D printer. The accuracy of 3D printing of the model part influences the realization of modular devices. In recent years, technology has evolved a lot, and the need to have the most efficient manufacturing equipment has increased. This is the reason for the development of 3D printers using FDM technology for plastic parts. The software used by these 3D printers used in FDM technology is very sophisticated, as they allow the manufacture of very precise 3D prototypes, identical to the designed 3D model, through modern additive manufacturing techniques. The quality and mechanical strength of the prototypes obtained using 3D printers is very good. The materials used by the 3D printers manufactured by FDM are cheap and accessible. These 3D printers are used to make three-dimensional objects (gears, flanges, bearings, covers, casings, mechanisms, figurines, interior and exterior design elements, architectural models, medical models).
文摘The temperature dependences of the dynamic-elastic and viscous susceptibilities have been measured for Au83Fe17, after cold-rolling. It is found that cold-rolling reduces the Curie temperature and raises the spin-freezing temperature remarkably. These results can be explained on the basis of the precipitation medal proposed by Borg and Violet.
基金support of the geoelectrical stations of the SES telemetric network by Basil Dimitropoulos,Spyros Tzigkos and George Lampithianakis
文摘The procedure by means of which the occurrence time of an impending mainshock can be identified by analyzing in natural time the seismicity in the candidate area subsequent to the recording of a precursory seismic electric signals（SES） activity is reviewed. Here, we report the application of this procedure to an MW5.4 mainshock that occurred in Greece on 17 November 2014. This mainshock（which is pretty rare since it is the strongest in that area for more than half a century） was preceded by an SES activity recorded on 27 July 2014, and the results of the natural time analysis reveal that the system approached the critical point（mainshock occurrence） early in the morning on 15 November 2014.
文摘The effect of H2O and the slow thermal annealing on the properties of pure silica (SiO2) and phosphosilicate (SiO2-P2O5) gel-glasses are presented. The monolithic samples have been prepared via sol-gel process using tetraethorthosilicate (TEOS), Si(C2H5O)4 and Triethylphosphate (TEP) (C2H5O)3P(O) as SiO2 and P2O5 precursors. Phosphate incorporates into the silicate network by substituting Si atoms and consequently, we observed changes in structural and spectroscopic properties for these systems. The structures of prepared samples were examined by observed weight loss, XRD and FTIR. It has been found that in the structure of pure silica and phosphosilicate glasses there are formed domains characterized by certain degree of ordering of the units present in their composition, while the structure of pure silica is still amorphous of these glasses. The changing character of domains structure may be the reason of different chemical activities of phosphosilicate glass.
文摘Several bacterial strains of Actinomycetes belonging to Streptomyces and Arthrobacter genera for the first time were used to study the biotechnology of synthesis of gold and silver nanoparticles. The experimental conditions of gold and silver nanoparticles production by the cells of studied strains in aqueous chloroauric acid （HAuCIq） and in silver nitrate （AgNO3） solutions, respectively, were determined. Concentration and time-dependences of nanoparticle formation were investigated. The complex of optical and analytical methods was used for testing the gold and silver nanoparticles in the bacterial biomass. The TEM （Transmission Electron Microscopy） and XRD （X-ray Diffraction） data in all cases demonstrated the presence of crystals with fcc （face centered cubic） structure. The results obtained show that the Actinomycetes are capable of producing gold and silver nanoparticles of spherical shape extracellularly when exposed to suitable compounds. The particle size distribution shows that the sizes of nanoparticles are in the range of 5 nm to 80 nm. The biomass obtained may be used for industrial as well as medical and pharmaceutical purposes.
文摘The results of optical investigation of hydrogenated epitaxial bilayer graphene are presented. A softening and an increase of the intensity of the in-plane anti-symmetric phonon mode are observed at 0.2eV. It is suggested that they both originate from coupling of the optically active phonon mode to virtual electronic transitions, which is related to the band structure of bilayer graphene and leads to the “charged phonon” effect. In addition, it is noted that optically active phonon peaks have pronounced Fano shapelines. It is argued that the Fano shapeline is attributed to the interaction of the phonon mode with a continuum of electronic transitions in valence bands of hydrogenated bilayer graphene.
文摘In this paper,the flux pinning effects in Y_(1-x)M_(x)Ba_(2)Cu_(3)O_(7-δ)(M=Gd,Eu and Sm)samples are reported.It is found that there is another pinning mechanism under higher magnetic fields in addition to that under lower fields.This pinning effect may stem from the lattice stress field resulting from the partial substitution of the rare earth elements with different atomic radii for Y.
文摘Nano-composite monolith and thin film Alumina-Phospho-Silicates (SiO<sub>2</sub>-P<sub>2</sub>O<sub>5</sub>-Al<sub>2</sub>O<sub>3</sub>):Ln (Ln = Sm, Er, Yb) glasses activated by triply doped with three different rare earth ions (REIs) (Er<sup>3+</sup>:Yb<sup>3+</sup>:Sm<sup>3+</sup>) were prepared by modified sol-gel process. The composition of the prepared samples was as follow (SiO<sub>2</sub>:11P<sub>2</sub>O<sub>5</sub>:3Al<sub>2</sub>O<sub>3</sub>:1.2Er<sub>2</sub>O<sub>3</sub>:(1.2 - 3)Yb<sub>2</sub>O<sub>3</sub>:(0.7 - 1.3)Sm<sub>2</sub>O<sub>3</sub>). Tetra-ethyl-orthosilicate (TEOS), tri-ethyl-phosphate (TEP), erbium nitrate, ytterbium nitrate and samarium nitrate were used as precursor materials, respectively. The structure of the prepared samples was studied using X-ray diffraction (XRD), which revealed that the crystallite sizes of monolith and thin film samples both sintered at 900℃ at constant Sm<sup>3+</sup> concentration at 1.3 mol% (SPAE<sub>1.2</sub>Y<sub>1.8</sub>S<sub>1.3</sub>) have the following values 44 and 31 nm, respectively. Transmission Electron Microscopy (TEM) of the same prepared samples was used to confirm the presence of nano-structure phase. The photo-luminescence study will be evaluated for the prepared.
文摘The interaction between graphene and germanium surfaces was investigated using a combination of microscopic and macroscopic experimental techniques and complementary theoretical calculations.Density functional theory （DFT） calculations for different reconstructions of the Ge（001） surface showed that the interactions between graphene and the Ge（001） surface introduce additional peaks in the density of states,superimposed on the graphene valence and conduction energy bands.The growth of graphene induces nanofaceting of the Ge（001） surface,which exhibits well-organized hill and valley structures.The graphene regions covered by hills are of high quality and exhibit an almost linear dispersion relation,which indicates weak graphene-germanium interactions.On the other hand,the graphene component occupying valley regions is significantly perturbed by the interaction with germanium.It was also found that the stronger graphene-germanium interaction observed in the valley regions is connected with a lower local electrical conductivity.Annealing of graphene/Ge（001）/Si（001） was performed to obtain a more uniform surface.This process results in a surface characterized by negligible hill and valley structures;however,the graphene properties unexpectedly deteriorated with increasing uniformity of the Ge（001） surface.To sum up,it was shown that the mechanism responsible for the formation of local conductivity inhomogeneities in graphene covering the Ge（001） surface is related to the different strength of graphene-germanium interactions.The present results indicate that,in order to obtain high-quality graphene,the experimental efforts should focus on limiting the interactions between germanium and graphene,which can be achieved by adjusting the growth conditions.
基金This work has been carried out in the frames of Federal Target Program of Russian Federation,GK No.P726 and No.14.740.11.0687.
文摘The development of micromechanical devices(MEMS and NEMS)on the basis of nanostructured shape memory alloys is reported.A Ti_(50)Ni_(25)Cu_(25)(at.%)alloy fabricated by the melt spinning technique in the form of a ribbon with a thickness around 40µm and a width about 1.5 mm was chosen as a starting material.Technological parameters were optimized to produce the alloy in an amorphous state.The thickness of the ribbon was reduced to 5–14µm by means of electrochemical polishing.A nanostructural state of the thin ribbons was obtained via the dynamic crystallization of the amorphous alloy by application of a single electric pulse with duration in the range of 300–900µs.A microtweezers prototype with a composite cantilever of 0.8µm thick and 8µm long was developed and produced on the basis of the obtained nanostructured thin ribbons by means of the focused ion beam technique.Controlled deformation of the micromanipulator was achieved by heating using semiconductor laser radiation in a vacuum chamber of scanning ion-probe microscope.
