Search results for "Biomaterial"
showing 10 items of 1350 documents
Influence of spatial arrangements of π-spacer and acceptor of phenothiazine based dyes on the performance of dye-sensitized solar cells
2013
Abstract Three phenothiazine based organic dyes PTA , PDTA and PTDA with D– π –A, π –D– π –A and A– π –D– π –A frameworks were designed and synthesized for the dye sensitized solar cells (DSSCs). Phenothiazine with octyloxyphenyl moiety acts as donor while thiophene and cyanoacetic acid units act as a π -spacer and an acceptor, respectively. The effects of the molecular structures of the dyes on the performance of the DSSCs were investigated systematically along with their photophysical and photoelectrochemical properties. The dye PTDA with A– π –D– π –A framework exhibited a better light harvesting capacity and an effective electron extraction pathway from the electron donor to the TiO 2 s…
Elastohydrodynamic Collision of Two Spheres Allowing Slip on Their Surfaces.
2000
Our goal is to study theoretically the effect of deformation on the collision of two solid spheres allowing slip on their surfaces. The deformed shape of the solid surface is determined via an asymptotic technique assuming that deformation is small compared with the separation between the surfaces. It has previously been shown that the slippage makes collision possible even without any surface attractive force. Here we demonstrate that even a small amount of deformation can preclude spheres from coagulation. Copyright 2000 Academic Press.
New aspects of scattering and absorbing properties of atmospheric aerosol particles
1972
Abstract Knowledge of the scattering and absorbing processes of the atmospheric aerosol particles in the solar wavelength range is necessary in order to calculate the energy balance of the atmosphere. Both of these depend on the relative humidity of the air. Until now little was known of the behavior of the particles. This paper shows experimental and theoretical results of the real and imaginary part of the refractive index of the aerosol particles at different relative humidities.
Dynamics of Colloidal Hard Spheres in Thin Aqueous Suspension Layers—Particle Tracking by Digital Image Processing and Brownian Dynamics Computer Sim…
1993
Abstract A new experimentally simple technique is introduced for studying dynamical properties of hard sphere colloids in thin aqueous suspension layers by light-microscopy observation supported by computer-aided digital image processing. The thickness of the layers of the colloidal samples confined between two smooth glass plates is accurately adjusted by monodisperse "spacer" spheres which are larger than the diffusing spheres. Tracking of single particles in concentrated phases is accomplished using fluorescence light microscopy where a few dyed particles are mixed with the undyed colloidal spheres of the same size. First results are presented for the self-diffusion coefficient—(i) in ve…
A Multipurpose Instrument To Measure the Vitreous Properties of Charged Colloidal Solids
2001
We present a new high-precision light-scattering setup to study the properties of colloidal solids. It combines static light scattering, dynamic light scattering, and torsional resonance spectroscopy with a flexible and reliable preparational procedure. All three experiments can be performed quasi-simultaneously on the same mechanically undisturbed sample. Thus, unequivocal identification of glassy behavior in a comprehensive characterization dependent on interaction parameters becomes possible. A detailed description of the mechanics is given. We thoroughly tested the new apparatus on dilute colloidal samples and against commercial reference instruments. We performed a first systematic ser…
Measuring the Contact Angle of Individual Colloidal Particles.
1998
The aim of this study was to measure the contact angles of individual colloidal spheres ( solidus in circle 4.4 µm) and compare it to contact angles obtained on similarly prepared planar surfaces. For this purpose the particles were attached to atomic force microscope cantilevers. Then the force between the particle in aqueous medium and an air bubble was measured versus the distance. From the resulting force curves we obtained contact angles and detachment forces of single particles. Contact angles of gold coated silica particles were adjusted between 20 degrees and 100 degrees by self-assembling monolayers from different mixtures of undecanethiols and omega-hydroxy undecanethiols from sol…
Pullulan and dextran: uncommon composition dependent Flory-Huggins interaction parameters of their aqueous solutions.
2008
Vapor pressure measurements were performed for aqueous solutions of pullulan ( M w 280 kg/mol) and dextran ( M w 60 and 2100 kg/mol, respectively) at 25, 37.5, and 50 degrees C. The Flory-Huggins interaction parameters obtained from these measurements, plus information on dilute solutions taken from the literature, show that water is a better solvent for pullulan than for dextran. Furthermore, they evince uncommon composition dependencies, including the concurrent appearance of two extrema, a minimum at moderate polymer concentration and a maximum at high polymer concentration. To model these findings, a previously established approach, subdividing the mixing process into two clearly separa…
Simulation Analysis of the Influence of Hemodialysis Control Parameters on Exchange Processes during Therapy
1992
The effect of dialysis control parameters (dialysate composition, ultrafiltration rate, blood flow rate) on the patient's internal milieu were studied using a mathematical model for the description of the dynamic exchange processes during hemodialysis. This model simulates the electrolyte and water distribution, the acid-base and the oxygenation state as well as the ventilation. The dialysate sodium concentration affects mainly the intra-/ extracellular water and the potassium distribution. The dialysate bicarbonate and acetate concentrations control the acid-base state and the electrolyte distribution (sodium and potassium). In addition, the dialysate acetate concentration has a strong ef…
Thermomagnetic Properties Improved by Self-Organized Flower-Like Phase Separation of Ferromagnetic Co2Dy0.5Mn0.5Sn
2012
A thermodynamically stable phase separation of Co2Dy0.5Mn0.5Sn into the Heusler compound Co2MnSn and Co8Dy3Sn4 is induced by rapid cooling from the liquid phase. The phase separation forms an ordered flower-like structure on the microscale. The increased scattering of phonons at the phase boundaries reduces the thermal conductivity and thus improves thermoelectric and spincaloric properties.
Comparative studies on cytotoxic effects of dental amalgams and alternative alloys according to ISO standards in vitro
1995
Deleterious effects of dental alloys, especially those of dental amalgams, have become an important issue in current discussions on biomaterials. Cytotoxicity and further related risks of amalgams are discussed in a controversial way in the literature without leading to a final conclusion. There is still a need for basic clinical and pre-clinical research, especially with respect to the wide distribution of dental amalgams. Standardized methods of cytotoxicity testing have been established by the ISO. It was the aim of the present study to detect and compare possible cytotoxic effects of dental amalgams and alternative non-amalgam alloys in vitro. According to the ISO standards, direct cont…