Integrated Solar-Panel Antenna Array for CubeSats

The goal of the Integrated Solar-Panel Antenna Array for CubeSats (ISAAC) project is to design and demonstrate an effective and efficien toptically transparent, high-gain, lightweight, conformal X-band antenna array that is integrated with the solar panels of a CubeSat. The targeted demonstration is for a Near Earth Network (NEN)radio at X-band, but the design can be easilyscaled to other network radios for higher frequencies. ISAAC is a less expensive and more flexible design for communication systemscompared to a deployed dish antenna or the existing integrated solar panel antenna design

A Study on the Applications and Toxicity Assessments of Carbon Nanotubes in Tissue Engineering

Carbon nanotubes (CNTs) are one of the most popular nanomaterials. There has been increasing interest in the development and applications of carbon nanotubes due to their huge potential in industrial and medical applications. Recent applications of carbon nanotubes include development of scaffolds and drug delivery systems. Despite rapidly emerging applications of CNTs, little is known about the impact of CNTs on cellular processes, especially mesenchymal stem cell (MSC)\u27s differentiation. Also, the effects of nanoparticle exposure under different conditions on cellular responses have not been well characterized yet. To characterize the effects of CNTs on creating nanoscale scaffolds for tissue engineering, we incorporated multi-walled CNTs (MWCNTs) into reconstituted type I collagen, and evaluated proliferation, differentiation, mineralization and inflammatory response of MSC on those scaffolds. MWCNTs were homogeneously distributed in collagen matrix, and strongly entrapped in collagen at the concentrations below 100 ppm. Alkaline phosphatase (AP) activity and mineralized nodules of extracellular matrix (ECM) were monitored as osteogenic differentiation markers. AP activity was significantly increased in 12 days after being replaced by differentiating media. Collagen enhanced AP activity, and MWCNT-collagen scaffolds induced additional increase in AP activity. The MSC released a significantly higher level of AP on MWCNT-collagen scaffolds than the plastic surface did at day 16. An increasing percentage of ECM mineralization was seen at day 16 after being replaced by differentiating media in the presence of MWCNT-collagen scaffolds. This study indicated the possibility of enhancement in MSC differentiation in the MWCNT-collagen scaffolds. The increased level of differentiation markers was due to the increased stiffness of the scaffolds for MSC. Our data indicated that the collagen-MWCNT scaffolds might have the potential application to create nanoscale scaffold materials for tissue engineering. To illustrate the effects of interleukin-8 (IL-8) expression in human alveolar epithelial cells (A549) under various exposure conditions of CNT, we measured the level of IL-8 expression in the presence and absence of serum following exposure of SWCNTs. The results demonstrated that the IL-8 expression was enhanced in the presence of serum. The IL-8 expression kept increasing at low concentration even after removing SWCNTs from the media. Further studies are required to characterize biological functions and toxicological potentials of nanomaterials

Design, Fabrication, and Tuning Techniques of Quadrifilar Helix Antennas for Small Satellites

Quadrifilar helix antennas are also called fractional turn helix is very appealing to spacecraft applications. A quadrifilar antenna offers circular polarization in its radiating hemisphere and its radiation pattern is not severely affected by a ground plane. These properties are important for closing the communication link and make the antenna relatively independent of the CubeSat frame and mounting location, which facilitates modular design of the antenna. Although it has similar shape as a helical antenna, a quadrifilar helix antenna is fundamentally different. While there exists design theory and calculators for this type of antennas, detailed notes on design, fabrication, and tuning of different geometries of quadrifilar helix antennas are beneficial for small satellite community. This paper presents design data of several successful demonstrations of quadrifilar helix antennas with different geometries and operation bands

Nanotoxicity Assessment toward the Applications of Carbon Nanotubes as a Small Biomolecule Carrier in Drug Delivery Systems

Carbon Nanotube (CNT) materials have superior properties in electric current carrying capacity, thermal conductivity, and thermal stability. Due to their structure with high aspect ratio, they have structural unusual toxicity and complicate safety issue in a target tissue. In optimized quantities with limited functionality, special type of CNT assembly such as “buckyball” can be used as a potential drug carrier of bioactive molecules and display with increased circulating time and acceptable functionality. We analyzed cytoxicity and inflammatory response following exposure of different size, mass, shape, and functionality of CNTs. We monitored the transport across skin, physiological perturbation of transepithelial electrical resistance (TER) during the exposure of different concentrations of CNTs. The mechanisms of CNTs’ toxicity are closely related to their structure, functional group, and surface charge on the molecule. We established the nanoscale toxicity of fullerenes of CNTs

Analysis and Design of Highly Transparent Meshed Patch Antenna Backed by a Solid Ground Plane

This paper analyzes rectangular and circular patch antennas fabricated from meshed conductors and backed with solid ground planes. Because of the meshing, the antennas are rendered optically transparent, where the transparency is determined by the mesh geometry. It is found that although there is a compromise between the antenna\u27s efficiency and the optical transparency of the meshed patch, it is possible to optimize the antenna by refining mesh lines to certain extent. The limiting factors for refining mesh lines include material handling and fabrication process as well as the increased line impedance when being refined, which accordingly causes loss in antenna\u27s efficiency or gain, it is seen that there is a limit for such an optimization method. This limit is closer to the efficiency of a solid patch for a lower transparency, whereas it is lower for increased transparency. Cross polarization level was also examined, and there was no significant effect on such a parameter due to meshing

Integrated Solar-Panel Antenna Array for CubeSats

The goal of the Integrated Solar-Panel Antenna Array for CubeSats (ISAAC) project is to design and demonstrate an effective optically transparent, high-gain, lightweight, conformal X band antenna array that is integrated with the solar panels of a CubeSat. The targeted demonstration is for a Near Earth Network (NEN) radio at X-band, but the design can be easily scaled to other network radios for higher frequencies. ISAAC is a less expensive and more flexible design for communication systems compared to a deployed dish antenna or the existing integrated solar panel antenna designs

A Study on the Effect between Commercial Space Solar Cells and the Antennas Integrated on Their Cover Glass

A study to determine how commercial space solar cells affect the functionality of the antenna integrated on top of solar cells has been performed. The measured results show that solar cell affects the antenna gain and decreases it by approximately 3 dB at 5GHz. In addition, the pattern of the antenna was not affected significantly by solar cells whether when they were illuminated and terminated with different loads

Recent advances in solid-state organic lasers

Organic solid-state lasers are reviewed, with a special emphasis on works published during the last decade. Referring originally to dyes in solid-state polymeric matrices, organic lasers also include the rich family of organic semiconductors, paced by the rapid development of organic light emitting diodes. Organic lasers are broadly tunable coherent sources are potentially compact, convenient and manufactured at low-costs. In this review, we describe the basic photophysics of the materials used as gain media in organic lasers with a specific look at the distinctive feature of dyes and semiconductors. We also outline the laser architectures used in state-of-the-art organic lasers and the performances of these devices with regard to output power, lifetime, and beam quality. A survey of the recent trends in the field is given, highlighting the latest developments in terms of wavelength coverage, wavelength agility, efficiency and compactness, or towards integrated low-cost sources, with a special focus on the great challenges remaining for achieving direct electrical pumping. Finally, we discuss the very recent demonstration of new kinds of organic lasers based on polaritons or surface plasmons, which open new and very promising routes in the field of organic nanophotonics

Design, Development, Implementation, and On-orbit Performance of the Dynamic Ionosphere CubeSat Experiment Mission

Funded by the NSF CubeSat and NASA ELaNa programs, the Dynamic Ionosphere CubeSat Experiment (DICE) mission consists of two 1.5U CubeSats which were launched into an eccentric low Earth orbit on October 28, 2011. Each identical spacecraft carries two Langmuir probes to measure ionospheric in-situ plasma densities, electric field probes to measure in-situ DC and AC electric fields, and a science grade magnetometer to measure in-situ DC and AC magnetic fields. Given the tight integration of these multiple sensors with the CubeSat platforms, each of the DICE spacecraft is effectively a “sensorsat” capable of comprehensive ionospheric diagnostics. The use of two identical sensor-sats at slightly different orbiting velocities in nearly identical orbits permits the de-convolution of spatial and temporal ambiguities in the observations of the ionosphere from a moving platform. In addition to demonstrating nanosat-based constellation science, the DICE mission is advancing a number of groundbreaking CubeSat technologies including miniaturized mechanisms and high-speed downlink communications