Search results

In simple terms, confining the antibonding wavefunction which is produced by moving an electron from a π valence state to a π∗ conduction band state to a small number of carbon-carbon bonds causes substantial rearrangement of the valence electrons so that the bond lengths change in response.
The absence of grain boundaries and the fact that the amorphous state is not associated with distorted or broken bonds can lead to trap-free charge transport - a key requirement in electrophotography.
The achievable quantum efficiency for an organic LED that emits from spin singlet excitons is determined by this and a number of other factors, often expressed as , (1) where η is the efficiency (photons out per electron injected), q is the photoluminescence efficiency, γ is the fraction of injected electrons and holes that recombine to form an exciton within the emissive semiconductor layer, rst is the fraction of excitons that are formed as spin-singlets, and fout is the fraction of the light generated within the device that is able to leave it in the forward direction.

In fact, the spin quantum number, S, may be either 0 or 1.
Theoretically, infinite number of singlet states exists for any molecule and are numbered in order of increasing energy, for example, S1 to Sn.
The quantum yield ф is defined as the ratio of the number of emitted photons to the number of absorbed photons per unit time.
Less the number of photons absorbed, more will be the number of photons emitted, and therefore, more the luminescence quantum yield.
The external quantum efficiency ηext of OLED can be defined as the ratio of the number as photons emitted by the OLED to the number of electrons injected.

The data were taken with substantially similar condition of TiO2 loading in the range of 10-12 g m 2 where the TiO2 layer contained a large TiO2 grain (250 nm) for light scattering enhancement and had porosity of about 60%.
Only a limited number of materials can replace Pt.
The number of unit cells connected in this fashion depends on the output voltage required.

From this figure, it is displayed that a large number of slip bands with different directions exist in the spherical particles.
The existence of large numbers of slip bands within the spherical β phase particles is direct evidence that the ductile crystalline phases deform through dislocation movement.
It is almost impossible for the propagating shear bands to cross through these spherical particles because of their proper morphology and the resulting large size, which induces a large number of fine fringe-like multiple shear bands concentrating on the interface between the spherical particles and glassy matrix.
Conclusions Large numbers of slip bands with different directions can be seen within ductile spherical particles on the surface of the compression specimens of the BMG composite containing micro-sized spherical bcc β-Zr(Ti, Nb) phase, which subjected to 9% and 12% plastic strain.
When met with spherical particles, the propagating shear bands were stopped by them, inducing a large number of fine shear bands concentrating on the interface of the spherical particles/glassy matrix.

The number, size and organization of sp2 clusters define the extent of modification in optical and electronic properties of a-C:H [63, 65, 66, 68].
Yang (Ed.), Nanotechnology-Enhanced Orthopedic Materials: Fabrications, Applications and Future Trends, Woodhead Publishing Series in Biomaterials, Number 102, Elsevier, Amsterdam, The Netherlands, 2015, pp. 97-120
Hajlaoui, Grain size dependent mobility in polycrystalline organic field-effect transistors, Synth.

Indeed, they offer a number of advantages over ceramic materials.
Yurek, Grain boundary segregation of yttrium in chromia scales, J.
Larpin, Segregation of neodymium in chromia grain-boundaries during high-temperature oxidation of neodymium oxide-coated chromia-forming alloys, Oxid.

Fig. 1: Reinforcement of metastable austenitic materials [16] For sheet-metal materials there exist a number of analyses that illustrate the effects of parameters on the martensite development and on the factors of increased strengthening.
Additionally, connections between the properties of the structural fields and the components, their grain structure as well as their martensite content shall be examined.
By furthering the research of the mechanisms that lead to martensite formation during the forming process, the material properties, and therefore the component properties, can be controlled at points under particular load, by means of localized adjustment or changing of the grain structure.

Metal-steam reforming results Figure 12 compares the hydrogen yield from metal-steam reforming reaction carried out at 600 oC by using elemental iron obtained via a number of reduction techniques employed in this work: namely, using hydrogen, carbothermic, sodium borohydride and, hydrazine.
In comparison, the effect of larger grain size (micro versus nano) of iron particles derived via high temperature hydrogen and carbothermic reduction techniques is reflected in the slower and more sluggish kinetics; in both the cases, hydrogen generation is seen to continue even after about 2 h of initiation.
Apart from the application of nano iron in MSR reaction to produce hydrogen discussed here, recent studies have shown a great number of applications for nanscale iron as well as magnetite among which arsenic, perchlorate and hexavalent chromium removal from drinking water sources and contrasting agents for magnetic resonance imaging (MRI) deserve mention.

ZrO2 and Ti implants - similar bone-implant responses in terms of BIC and RT. 7 Hoffmann et al [18] 2012 Rabbit femur 96 impl (24x4) ZrO2 sintered  ZrO2 laser-modified, ZrO2 SL Ti – acid etched 6/12 weeks BIC - Comparable rates of bone apposition in the zirconia and titanium implant surfaces at 6 and 12 weeks. 8 Aboushelib et al [19] 2013 Rabbit femur 60 impl/40 rabbits SIE-ZrO2 ZrO2 sintered Ti-sintered 4/6 weeks BIC 4 weeks SIE-ZrO2 - 65.38±5.7 ZrO2 sintered - 53.30 ± 4.2 Ti-sintered - 56.93 ± 3.9 SEM - SIE created a nano-porous surface through inter-grain porosities compared to the dense surface of Zr-sintered 9 Salem et al [20] 2013 Rabbit femur 90 impl in 30 rabbits ZrO2 ZrO2 fusion sputtered Ti - SLA 4/8/12 weeks BIC - significantly greater bone-implant contact for ZrO2 fusion-sputtered implants compared to Ti after 4 and 8 weeks of healing time, with no significant difference at 12 weeks. 10 Chung et al [21] 2013 Rabbit tibiae 100 implants / 25 rabbits PIM- Zr rPIM
The limited number of animals per group, however, does not allow the conclusion that there is no difference in osseointegration between the two types of implants, although the data tend to suggest such a trend [34].
No Author Year Animal design No of implants Material used Period of study Histomorphometric test 1 Franchi et al [40] 2004 Sheep femur &tibiae 30 impl / 2 mongrel sheep SS Ti TPS – Ti ZrO2-SLA 2 weeks 3 months SEM - rough surfaces, and in particular Zr-SLA, seem to better favour bone deposition on the metal surface. 2 Franchi et al [41] 2007 Sheep tibiae 72 impl ZirTi- SLA 60 ZirTi- SLA 120 Ti 2/ 4 weeks The highest values of BIC, BI, BS/BV, and Vickers hardness number (HV) were measured in SLA-60 samples, followed by SLA-120 and T implants 3 Langhoff et al [42] 2008 Sheep pelvis 6 types of impl Ti, Ti + CaP, Ti + Bisphos, Ti + collagen + CS Ti + APC ZrO2 - SLA 2/ 4/ 8 weeks BIC - All titanium implants had similar bone implant contact (BIC) at 2 weeks (57-61%); only zirconia was better (77%).

Incorporation of sand as a fine aggregate in the FC acts in a similar way to the coarse aggregate in the NC, and also provides the shear resistance between its grains, which decreases the drying shrinkage [3, 49].
The greater the number of pores and openings exposed to the environment, the greater the entry of harmful substances into the mass of material and, thus, their durability is reduced [53].
Similarly, the inclusion of fine grain mineral additions increases the compressive strength of FC.