| 1. |
- Soltanmoradi, Reyhaneh, et al.
(författare)
-
Multi-resonator structure based on continuous silver thin films for transparent conductors
- 2014
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 105:6, s. 061110-
-
Tidskriftsartikel (refereegranskat)abstract
- A type of metal-dielectric multilayered structures is investigated theoretically and experimentally for achieving optical transparency with a high electrical conductivity. The structure in our demonstrated case comprises of two coupled metal-dielectric-metal planar optical resonators with metal-layer thicknesses near to its skin depth. Simulations show that the maximum transmittance for visible light can easily reach 90% for silver-based structures. Experimentally, the sample fabricated exhibits a transmission window with a bandwidth of 150 nm and a maximum transmittance of 76% around 643 nm wavelength at normal incidence. Its sheet resistance is measured to be less than 10 Omega/square, much smaller than that of common indium-tin-oxide films. Transparent conductors functioning for blue light and even for the whole visible light are also shown to be theoretically possible. Owing to their simple fabrication procedure as well as design flexibility, such a layered structure can serve as a compelling alternative as transparent conductors for optoelectronic devices, especially for liquid-crystal displays and light-emitting diodes.
|
|
| 2. |
- Soltanmoradi, Reyhaneh, et al.
(författare)
-
Near-infrared light absorption and scattering based on a mono-layer of gold nanoparticles
- 2015
-
Ingår i: Journal of the European Optical Society-Rapid Publications. - : European Optical Society. - 1990-2573. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- We report fabrication and characterization of large-area ultrathin near-infrared light absorbers and scatterers based on amono-layer of gold nanoparticles laying on top of a dielectric spacer and an aluminum reflector. The nanoparticles are formed through thermal annealing of an evaporated continuous gold film. Through optimization of initial gold-film thickness, spacer thickness, as well as annealing temperature we obtained samples that exhibit very low (~2%) broadband specular reflectance at near-infrared (NIR) wavelength range. By considering also diffuse reflection, we identify that the low specular reflectance can be due to either relatively high light absorption (~70%) or high light scattering (over 60%), with the latter achieved for samples having relatively sparse gold nanoparticles. Both strong absorption and scattering of NIR light are not inherent properties of the bulk materials used for fabricating the samples. Such composite optical surfaces can potentially be integrated to solar-energy harvesting and LED devices.
|
|
| 3. |
- Liu, Chao, et al.
(författare)
-
Hyaluronan and phospholipids in boundary lubrication
- 2012
-
Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-683X .- 1744-6848. ; 8:40, s. 10241-10244
-
Tidskriftsartikel (refereegranskat)abstract
- Hyaluronan has been found to play an important role in boundary lubrication in joints, but model experiments have shown that free hyaluronan is reluctant to stay between surfaces. We show that hyaluronan, when assisted by a phospholipid bilayer, can act as a boundary lubricant, even at pressures well above those leading to breakdown of cartilage.
|
|
| 4. |
- Raj, Akanksha, et al.
(författare)
-
Lubrication synergy : Mixture of hyaluronan and dipalmitoylphosphatidylcholine (DPPC) vesicles
- 2017
-
Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 0021-9797 .- 1095-7103. ; 488, s. 225-233
-
Tidskriftsartikel (refereegranskat)abstract
- Phospholipids and hyaluronan have been implied to fulfil important roles in synovial joint lubrication. Since both components are present in synovial fluid, self-assembly structures formed by them should also be present. We demonstrate by small angle X-ray scattering that hyaluronan associates with the outer shell of dipalmitoylphophatidylcholine (DPPC) vesicles in bulk solution. Further, we follow adsorption to silica from mixed hyaluronan/DPPC vesicle solution by Quartz Crystal Microbalance with Dissipation measurements. Atomic Force Microscope imaging visualises the adsorbed layer structure consisting of non-homogeneous phospholipid bilayer with hyaluronan/DPPC aggregates on top. The presence of these aggregates generates a long-range repulsive surface force as two such surfaces are brought together. However, the aggregates are easily deformed, partly rearranged into multilayer structures and partly removed from between the surfaces under high loads. These layers offer very low friction coefficient (<0.01), high load bearing capacity (≈23 MPa), and self-healing ability. Surface bound DPPC/hyaluronan aggregates provide a means for accumulation of lubricating DPPC molecules on sliding surfaces.
|
|
| 5. |
- Raj, Akanksha, et al.
(författare)
-
Molecular synergy in biolubrication: The role of cartilage oligomeric matrix protein (COMP) in surface-structuring of lubricin.
- 2017
-
Ingår i: Journal of colloid and interface science. - : Elsevier BV. - 1095-7103 .- 0021-9797. ; 495, s. 200-206
-
Tidskriftsartikel (refereegranskat)abstract
- Synovial surfaces are lubricated by biomolecular aggregates that act in synergy, and lubricin is one key biolubricant. Its molecular structure allows extensive hydration and this is conducive to its lubrication performance. However, in order to fullfil its lubrication function it needs to be anchored and oriented on the surface in a proper way. We suggest that cartilage oligomeric matrix protein (COMP) is one of the biomolecules that promotes anchoring of lubricin in a fashion that facilitates lubrication.Weakly hydrophobic poly(methyl methacrylate) (PMMA) surfaces were coated by COMP and lubricin, individually and in combinations. Adsorption was investigated using a quartz crystal microbalance, and friction between the biopolymer-coated surfaces was determined by employing the atomic force microscope-colloidal probe technique.It was found that COMP facilitated firm directed attachment of lubricin in a manner that resulted in low friction forces, significantly lower than what was achieved when lubricin was directly adsorbed to PMMA. Evidently, COMP provides means for lubricin to attach strongly and in a favourable conformation for efficient lubrication of this surface. We suggest that our findings can be extrapolated to cartilage surfaces, where co-localization of COMP and lubricin has been demonstrated.
|
|
| 6. |
- Soltanmoradi, Reyhaneh, et al.
(författare)
-
Spectral selectivity of subwavelength gold-based photonic crystals on GaAs substrate
- 2013
-
Ingår i: 2013 7th International Congress on Advanced Electromagnetic Materials in Microwaves and Optics, METAMATERIALS 2013. - : IEEE Computer Society. - 9781479912292 ; , s. 100-102
-
Konferensbidrag (refereegranskat)abstract
- Gold-based subwavelength photonic crystal (PhC) structures on GaAs substrate have been fabricated on a wafer scale. The structures have then been characterized and compared with related simulation results. Integrating these gold-based PhC structures onto III-V semiconductor infrared (IR) photodetectors through a top-down approach has promising potential to enhance detector's performance; especially as its wafer scale fabrication method enables the direct adaption to high volume IR detector processing line.
|
|
| 7. |
- Soltanmoradi, Reyhaneh, et al.
(författare)
-
Transmission of Infrared Radiation Through Metallic Photonic Crystal Structures
- 2013
-
Ingår i: IEEE Photonics Journal. - 1943-0655. ; 5:5, s. 4500608-
-
Tidskriftsartikel (refereegranskat)abstract
- Monolithic integration of a metallic photonic crystal (mPhC) structure onto semiconductor infrared (IR) photodetectors can enhance the detector performances. In order to experimentally investigate the parameters involved in optimizing the transmission spectra of the mPhC structures matching the detector operating wavelength in mid- and long-wave IR (MWIR and LWIR) regimes, square thin gold (Au) hole arrays having periodicities of 4.0, 3.6, 2.4, and 1.8 mu m with various fill factors were fabricated on Si or GaAs substrates in a wafer scale. The thicknesses of the Au films are 50, 100, and 200 nm, respectively. Through this systemic study, suitable mPhC structures were revealed that can be readily integrated onto our type-II InGaSb-based quantum dot MWIR and LWIR photodetectors.
|
|
| 8. |
- Wang, Min, et al.
(författare)
-
Hyaluronan and Phospholipid Association in Biolubrication
- 2013
-
Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 14:12, s. 4198-4206
-
Tidskriftsartikel (refereegranskat)abstract
- It is becoming increasingly clear that the outstanding lubrication of synovial joints is achieved by a sophisticated hierarchical structure of cartilage combined with synergistic actions of surface-active components present in the synovial fluid. In this work we focus on the association of two components of the synovial fluid, hyaluronan and dipalmitoyl phosphatidyl choline (DPPC), in bulk solution and at interfaces. We demonstrate that hyaluronan associates with DPPC vesicles and adsorbs to supported DPPC bilayers. The association structures formed at the interface are sufficiently stable to allow sequential adsorption of DPPC and hyaluronan, whereby promoting the formation of thick composite layers of these two components. The lubricating ability of such composite layers was probed by the AFM colloidal probe technique and found to be very favorable with low friction coefficients and high load bearing capacity. With DPPC as the last adsorbed component, a friction coefficient of 0.01 was found up to pressures significantly above what is encountered in healthy synovial joints. Hyaluronan as the last added component increases the friction coefficient to 0.03 and decreases the load bearing capacity somewhat (but still above what is needed in the synovial joint). Our data demonstrate that self-assembly structures formed by hyaluronan and phospholipids at interfaces are efficient aqueous lubricants, and it seems plausible that such self-assembly structures contribute to the exceptional lubrication of synovial joints.
|
|
| 9. |
- Wang, Min, et al.
(författare)
-
The effect of temperature on supported dipalmitoylphosphatidylcholine (DPPC) bilayers : Structure and lubrication performance
- 2015
-
Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 0021-9797 .- 1095-7103. ; 445, s. 84-92
-
Tidskriftsartikel (refereegranskat)abstract
- Phospholipids fulfill an important role in joint lubrication. They, together with hyaluronan and glycoproteins, are the biolubricants that sustain low friction between cartilage surfaces bathed in synovial fluid. In this work we have investigated how the friction force and load bearing capacity of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) bilayers on silica surfaces are affected by temperature, covering the temperature range 25–52 °C. Friction forces have been determined utilizing the AFM colloidal probe technique, which showed that DPPC bilayers are able to provide low friction forces over the whole temperature interval. However, the load bearing capacity is improved at higher temperatures. We interpret this finding as being a consequence of lower rigidity and higher self-healing capacity of the DPPC bilayer in the liquid disordered state compared to the gel state. The corresponding structure of solid supported DPPC bilayers at the silica–liquid interface has been followed using X-ray reflectivity measurements, which suggests that the DPPC bilayer is in the gel phase at 25 °C and 39 °C and in the liquid disordered state at 55 °C. Well-defined bilayer structures were observed for both phases. The deposited DPPC bilayers were also imaged using AFM PeakForce Tapping mode, and these measurements indicated a less homogeneous layer at temperatures below 37 °C.
|
|
| 10. |
- Wieland, D. C. Florian, et al.
(författare)
-
Studying solutions at high shear rates : A dedicated microfluidics setup
- 2016
-
Ingår i: Journal of Synchrotron Radiation. - : International Union of Crystallography. - 0909-0495 .- 1600-5775. ; 23:2, s. 480-486
-
Tidskriftsartikel (refereegranskat)abstract
- The development of a dedicated small-angle X-ray scattering setup for the investigation of complex fluids at different controlled shear conditions is reported. The setup utilizes a microfluidics chip with a narrowing channel. As a consequence, a shear gradient is generated within the channel and the effect of shear rate on structure and interactions is mapped spatially. In a first experiment small-angle X-ray scattering is utilized to investigate highly concentrated protein solutions up to a shear rate of 300000 s-1. These data demonstrate that equilibrium clusters of lysozyme are destabilized at high shear rates.
|
|
