Interferometric determination of sphere radii is a well known technique. To keep accuracy high and uncertainties low, a precisely controlled environment is usually necessary. Environmental changes in ...temperature lead to time dependent drift in important measurement parameters and to disturbed results. We present a method to minimize time dependent drift to the first order. With this method, it is either possible to reduce the uncertainties further, or to relax environmental conditions and still be able to accomplish high precision measurements. We discuss two typical measurement configurations, the associated benefits and drawbacks and some relevant error sources.
In classical interferometric null test measurements, the measurement and reference beam path should be the same. A difference in the beam paths results in the so called retrace error. One very common ...approach to avoid retrace errors is to adapt the measurement wavefront to the reference wavefront with a computer generated hologram (CGH), which is costly and time consuming. A much more flexible approach is to do non nulltest measurement in combination with mathematical treatment of retrace errors. Most of such methods are based on iterative optimization or calibration of the nominal optical design of the interferometer. While this may be a convenient solution in the context of research, the more common use may be limited due to the need of the optical design of all interferometer components. In many cases, the optical designs of standard off the shelf optical assemblies are not available or disclosed by the manufacturer. This is especially true for transmission spheres of interferometers. We introduce the so called Black Box Model (BBM), used in the well known Tilted Wave Interferometry (TWI), as a mathematical model to account for retrace errors in interferometry. The Black Box Model is based on point characteristic functions which are adapted to the result and behavior of a real interferometer by calibration. With an extended calibration method, the need of a specific optical design of the interferometer is no longer necessary. Thus the method is attractive for a wide field of use in interferometry with standard off the shelf components.
Poultry industry paradigms: connecting the dots Castro, F.L.S.; Chai, L.; Arango, J. ...
Journal of applied poultry research,
March 2023, 2023-03-00, 2023-03-01, Letnik:
32, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Providing high-quality food for the increasing world population with limited natural resources is a challenge for animal agriculture. Over the past decades, poultry production has undergone ...remarkable advancements to adapt to emerging challenges and evolving changes in consumer expectations. Among these changes, the need for an animal protein production system that considers the social, economic, and environmental aspects of sustainability has increased. With that in mind, efforts were and will continue to be made toward improving various aspects of the poultry production chain. Genetic selection has evolved from a simple phenotypic mass selection to the use of genomics, focusing not only on efficiency, but also on animal welfare and the demand from niche markets. Precision poultry farming technologies should be further innovated to develop the core component of an integrated imaging system for evaluating poultry production and wellbeing. Moreover, feed formulation will continue to be adjusted as the birds' nutritional requirements, feed ingredient availability, and cost change, and bird processing will continue to adopt technologies that can improve meat quality and reduce labor intensity and demand. These adaptations highlight a dynamic aspect of the poultry industry and its continuous effort to produce a safe, cost-effective, and environment friendly protein source while maintaining animal welfare.
Cryogels made of components of natural extracellular matrix components are potent biomaterials for bioengineering and regenerative medicine. Human dermal fibroblasts are key cells for tissue ...replacement during wound healing. Thus, any biomaterial for wound healing applications should enable growth, differentiation and matrix synthesis by these cells.
Cryogels are highly porous scaffolds consisting of a network of interconnected pores. Here, we used a novel group of cryogels generated from acrylated hyaluronan where the polymerization was initiated by accelerated electrons (E-beam). This novel procedure omits any toxic polymerization initiators and results in sterile, highly elastic scaffolds with adjustable pore size, excellent swelling and low flow resistance properties.
We show that these cryogels are effective 3D-substrates for long-term cultures of human dermal fibroblasts in vitro. The cells proliferate for at least 28days throughout the cryogels and deposit their own matrix in the pores. Moreover, key modulators of dermal fibroblasts during wound healing like TGFβ and PDGF efficiently stimulated the expression of wound healing-relevant genes.
In conclusion, electron beam initiated cryogels of acrylated hyaluronan represent a functional and cell compatible biomaterial that could be adapted for special wound healing applications by further functionalization.
Summary
Shortly after its development, the white light supercontinuum laser was applied to confocal scanning microscopy as a more versatile substitute for the multiple monochromatic lasers normally ...used for the excitation of fluorescence. This light source is now available coupled to commercial confocal fluorescence microscopes. We have evaluated a supercontinuum laser as a source for a different purpose: confocal interferometric imaging of living cells and artificial models by interference reflection. We used light in the range 460–700 nm where this source provides a reasonably flat spectrum, and obtained images free from fringe artefacts caused by the longer coherence length of conventional lasers. We have also obtained images of cytoskeletal detail that is difficult to see with a monochromatic laser.
Electrical steels with lower thickness become more and more important to realize electrical machines with high nominal frequency due to high number of the poles and to provide higher power at a given ...volume of the electrical machine. For application at higher frequencies the dynamic magnetization processes have to be analyzed. In the paper the experimental data for frequency dependence of the magnetization curves, the coercive force, the permeability, and of the magnetic losses for nonoriented electrical steels with thicknesses in the range of 0.10 mm up to 0.50 mm will be reported. For thin electrical steels a different character of the dynamic magnetization behavior at increasing frequency of the applied external field compared to thicker materials is observed. This is attributed to differences in the number of moving walls.
Development of an Implantable Pulse Oximeter Reichelt, Stephan; Fiala, Jens; Werber, Armin ...
IEEE transactions on biomedical engineering,
02/2008, Letnik:
55, Številka:
2
Journal Article
Recenzirano
A long-term implantable photoplethysmographic sensor system is proposed. The system employs an elastic cuff which is directly wrapped around an arterial blood vessel. The optically transparent cuff ...is equipped with light emitting diodes and a photo transistor including the technology of pulse oximetry. The sensor will permit real-time, continuous monitoring of important vital parameters such as arterial blood oxygen saturation and pulse rate over a long-term period in vivo. We emphasize on the specific requirements for design and instrumentation of the implantable sensor and discuss first in vitro data acquired with that new photonics-based sensor.
This paper focuses on the characterization and use of polymer-modified phosphatidylcholine (PC)/sodium dodecyl sulfate (SDS)-based inverse microemulsions as a template phase for BaSO
4 nanoparticle ...formation. The area of the optically clear inverse microemulsion phase in the isooctane/hexanol/water/PC/SDS system is not significantly changed by adding polyelectrolytes, i.e., poly(diallyldimethylammonium chloride) (PDADMAC), or amphoteric copolymers of diallyldimethylammonium chloride and maleamid acid to the SDS-modified inverse microemulsion. Shear experiments show non-Newtonian flow behavior and oscillation experiments show a frequency-dependent viscosity increase (dilatant behavior) of the microemulsions. Small amounts of bulk water were identified by means of differential scanning calorimetry. One can conclude that the macromolecules are incorporated into the individual droplets, and polymer-filled microemulsions are formed. The polymer-filled microemulsions were used as a template phase for the synthesis of BaSO
4 nanoparticles. After solvent evaporation the nanoparticles were redispersed in water and isooctane, respectively. The polymers incorporated into the microemulsion are involved in the redispersion process and influence the size and shape of the redispersed BaSO
4 particles in a specific way. The crystallization process mainly depends on the type of solvent and the polymer component added. In the presence of the cationic polyelectrolyte PDADMAC the crystallization to larger cubic crystals is inhibited, and layers consisting of polymer-stabilized spherical nanoparticles of BaSO
4 (6 nm in size) will be observed.
Summary
In this paper, differential phase imaging (DPC) with transmitted light is implemented by adding a suitable detection system to a standard commercially available scanning confocal microscope. ...DPC, a long‐established method in scanning optical microscopy, depends on detecting the intensity difference between opposite halves or quadrants of a split photodiode detector placed in an aperture plane. Here, DPC is compared with scanned differential interference contrast (DIC) using a variety of biological specimens and objective lenses of high numerical aperture. While DPC and DIC images are generally similar, DPC seems to have a greater depth of field. DPC has several advantages over DIC. These include low cost (no polarizing or strain‐free optics are required), absence of a double scanning spot, electronically variable direction of shading and the ability to image specimens in plastic dishes where birefringence prevents the use of DIC. DPC is also here found to need 20 times less laser power at the specimen than DIC.
A novel technique for absolute calibration the wavefront reconstructed by computer generated holograms (CGHs) is presented. It requires a specially designed multiplexed CGH (Twin-CGH), which ...reconstructs two wavefronts with the same symmetry. One of those is used for calibration of the CGH by means of known absolute interferometric methods. The patterns of both phase functions are simultaneously structured. The aberrations of the calibration wavefront can be transferred to those of the second wavefront. The testing method is explained and two different encoding methods are discussed. For different encoded Twin-Fresnel zone plates we experimentally demonstrate this novel calibration method.
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