Adipose-derived stromal/stem cells (ASC) are multipotent with abilities to differentiate into multiple lineages including connective tissue and neural cells. Despite unlimited opportunity and needs for human and veterinary regenerative medicine, applications of adipose-derived stromal/stem cells are at present very limited. Furthermore, the fundamental biological factors regulating stemness in ASC and their stable differentiation into other tissue cells are not fully understood. The objective of this review was to provide an update on the current knowledge of the nature and isolation, molecular and epigenetic determinants of the potency, and applications of adipose-derived stromal/stem cells, as well as challenges and future directions. The first quarter of the review focuses on the nature of ASC, namely their definition, origin, isolation and sorting methods and multilineage differentiation potential, often with a comparison to mesenchymal stem cells of bone marrow. Due to the indisputable role of epigenetic regulation on cell identities, epigenetic modifications (DNA methylation, chromatin remodeling and microRNAs) are described broadly in stem cells but with a focus on ASC. The final sections provide insights into the current and potential applications of ASC in human and veterinary regenerative medicine.

Abstract-In this paper, novel compact broadband dual frequency microstrip antennas are presented and broad-band impedance matching is proposed as a method for improve the matching level of antennas. The first proposed design consists of a rectangular microstrip antenna with a pair of parallel slots loaded close to the radiating edge of the patch and three meandering narrow slots embedded in the antenna surface. The second proposed design consists of a rectangular microstrip antenna with a meandering slits. With the first proposed design a size reduction of 34% and 45% for the two resonant frequencies is obtained respectively. The two frequencies have an operation frequency ratio of 1.30 and 1.25. The theoretical design implementation of compensated compact rectangular microstrip antennas with new configuration Pi-matching networks was presented. A new compensation network consisting of RC Mutator circuit and discrete capacitors are employed at the input of the microstrip antenna operating at 1.5 GHz and 2.5 GHz. The performance parameters of the designed microstrip antenna with and without compensation network were compared. The results show that compensation network can improve the return loss level and the resonant frequency can be controlled in a wide RF band.

In this study, a novel technique for bandwidth enhancement of a microstrip antenna with a floating negative inductor matching network is presented. A compensation network consisting of three gallium-arsenide field effect transistors is employed at the input of a microstrip antenna operating at 10 GHz. The performance parameters of the designed microstrip antenna with and without compensation network are compared. The simulation results show that compensation network can improve the bandwidth from 17.21% to 32.67%.

Abstract-Various communication systems require single radiating element operating in wide band. In this paper, a novel active integrated single microstrip antenna is proposed and its radiation pattern and gain performance is optimized with analysis. The reactive loading is provided by a negative capacitor section embedded within the patch. The active negative capacitor is made of a field-effect transistor that exhibits negative resistance as well as capacitance. It can, therefore, compensate the loss of an inductor. A microstrip patch operating at 10.5 GHz having 12.2% bandwidth has been utilized as a reference antenna. With the proposed antenna design, the antenna radiation pattern can be as large as about 1.5 times that of an antenna without reactive loading. In addition, it has been shown that active compensation significantly improves the matching level.

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