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Posted in: Blog

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Cell Technology Tackles 3D Medical Imaging Reconstruction Challenges

Medical imaging is an information processing technique that takes data samples from medical devices such as magnetic resonance imaging (MRI) or computer tomography (CT) scanners and translates them into 2D, 3D or even 4D images. Advances in sensor technology allow for the generation of an increasing number of images per procedure and per patient, posing a tremendous challenge for the efficient, in-time processing and visualization of the resulting images. In addition, sensor systems are now capable of acquiring thousands of projections per second, literally flooding the image reconstruction subsystem with several hundreds of Mbytes of data per second.

Posted in: Articles

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Ultraviolet-Resistant Bacterial Spores

A document summarizes a study in which it was found that spores of the SAFR-032 strain of Bacillus pumilus can survive doses of ultraviolet (UV) radiation, γ radiation, and hydrogen peroxide in proportions much greater than those of other bacteria. The study was part of a continuing effort to understand the survivability of bacteria under harsh conditions and develop means of sterilizing spacecraft to prevent biocontamination of Mars that could interfere with the search for life there.

Posted in: Medical, Briefs

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Effects of Bone Morphogenic Proteins on Engineered Cartilage

A report describes experiments on the effects of bone morphogenic proteins (BMPs) on engineered cartilage grown in vitro. In the experiments, bovine calf articular chondrocytes were seeded onto biodegradable polyglycolic acid scaffolds and cultured in, variously, a control medium or a medium supplemented with BMP-2, BMP-12, or BMP-13 in various concentrations. Under all conditions investigated, cell-polymer constructs cultivated for 4 weeks macroscopically and histologically resembled native cartilage. At a concentration of 100 ng/mL, BMP-2, BMP-12, or BMP-13 caused (1) total masses of the constructs to exceed those of the controls by 121, 80, or 62 percent, respectively; (2) weight percentages of glycosaminoglycans in the constructs to increase by 27, 18, or 15, respectively; and (3) total collagen contents of the constructs to decrease to 63, 89, or 83 percent of the control values, respectively. BMP-2, but not BMP-12 or BMP-13, promoted chondrocyte hypertrophy.

Posted in: Medical, Briefs

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Laser Scanning Improves Dimensional Accuracy of Automotive Gas Tanks

In the past, one of the world’s leading manufacturers of fuel tanks used coordinate measuring machines (CMMs) to inspect first articles. The geometry of the tanks is so complex, however, that it was difficult to fully inspect the surface one point at a time. Inergy Automotive Systems has achieved significant improvements in quality by switching to laser scanning, which “paints” the surface of the tank with a laser and then uses a sensor to capture all the points in the laser’s path. The new approach generates a solid model of the as-built part that can be compared to the design intent to highlight the full extent of any differences between the two. As a result, Inergy can make required tooling changes with a higher level of confidence and ensure that production parts meet customer specifications.

Posted in: Features, ptb catchall, Photonics, Articles

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Nanotechnology’s Role in Mid-Infrared Laser Development

Progress in developing improved semiconductor lasers with emission in the mid-IR spectral region (≈3 μm to ≈15 μm) has depended heavily on the use of nanometer-scaled structures. Mid-IR quantum cascade lasers (QCLs), for example, represent a “tour de force” of semiconductor nanotechnology where large band gap GaAs and InP based III-V semiconductor multiple quantum well (MQW) structures are used to engineer intersubband transition energies that enable mid-IR photon emission. First developed at Bell Labs and now demonstrated by many other groups, QCLs have offered great hope as a new mid-IR light source for applications such as trace gas sensing [1] and isotope ratio measurement [2]. However, from their first use [3], QCL operation has been complicated by high power inputs, typically a minimum of 5 watts, and associated high heat load in packaged systems. Considering the significant resources devoted to QCL development and the apparent lack of progress in reducing high power consumption levels over the last ten years, it is likely that this problem is fundamental to QCL design. QCLs require high applied voltages (>8 volts) to achieve the necessary band alignment and the cascade effect, so focusing on this contribution is not expected to be fruitful. The other contribution, high threshold current (≈300 mA), appears to be fundamental to all intersubband lasers where there are parallel energy versus momentum dispersion relationships for electrons associated with intraband laser transitions. Figure 1, which depicts E vs. k subband dispersion for a three-level QCL gain medium, shows that there is an efficient competing non-radiative relaxation pathway for excited electrons when they scatter with non-zone-center optical or acoustic phonons. Since low energy subband separation is required for mid-IR light emission and the sub-band dispersions are parallel, such electron-phonon scattering will always be an efficient upper laser state depopulation mechanism thus necessitating high electron currents to achieve population inversion. Note, as indicated in Figure 1, the deliberate use of electron-phonon resonance with longitudinal optical (LO) phonons in QCL designs to depopulate the lower laser transition subband states. Exploitation of such electrophonon resonance effects in reducing laser threshold currents will be discussed below within the context of interband IV-VI mid-IR lasers.

Posted in: ptb catchall, Applications, Photonics, Application Briefs

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Electroform/Plasma-Spray Laminates for X-Ray Optics

Properties of lightweight components can be optimized. Goddard Space Flight Center, Greenbelt, Maryland Electroform/ plasma-spray laminates have shown promise as lightweight, strong, low-thermal-expansion components for x-ray optics. The basic idea is to exploit both (1) the well-established art of fabrication of optical components by replication and (2) plasma spraying as a means of reinforcing a thin replica optic with one or more backing layer(s) having tailorable thermomechanical properties. In x-ray optics as in other applications, replication reduces the time and cost of fabrication because grinding and polishing can be limited to a few thick masters, from which many lightweight replicas can thereafter be made.

Posted in: Tech Briefs, ptb catchall, Photonics, Briefs

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