Compact Brillouin devices through hybrid integration on Silicon

A range of unique capabilities in optical and microwave signal processing have been demonstrated using stimulated Brillouin scattering. The desire to harness Brillouin scattering in mass manufacturable integrated circuits has led to a focus on silicon-based material platforms. Remarkable progress in silicon-based Brillouin waveguides has been made, but results have been hindered by nonlinear losses present at telecommunications wavelengths. Here, we report a new approach to surpass this issue through the integration of a high Brillouin gain material, As2S3, onto a silicon chip. We fabricated a compact spiral device, within a silicon circuit, achieving an order of magnitude improvement in Brillouin amplification. To establish the flexibility of this approach, we fabricated a ring resonator with free spectral range precisely matched to the Brillouin shift, enabling the first demonstration of Brillouin lasing in a silicon integrated circuit. Combining active photonic components with the SBS devices shown here will enable the creation of compact, mass manufacturable optical circuits with enhanced functionality

A wideband 3-dB directional coupler in GGW for use in V-Band communication systems

In this article, a broadband 3-dB directional coupler is proposed using groove gap waveguide (GGW) structures. Gap waveguide technology has been introduced to overcome manufacturing and assembling challenges of different millimeter-wave components and devices. The presented coupler has wideband coupling flatness with low return loss in 60-GHz frequency band and can be easily adapted to other frequency ranges. Experimentally, a sample prototype of the proposed 3-dB coupler has been designed and fabricated. The measured return loss and isolation are better than 20 dB and the power-split unbalance within \ub10.5 dB is obtained over the frequency range from 57 to 74 GHz (26% BW). The proposed structure has the capability of easily integrating with other millimeter-wave components

60-GHz Groove Gap Waveguide Based Wideband H-Plane Power Dividers and Transitions: For Use in High-Gain Slot Array Antenna

Wideband design of power dividers, T-junctions, and transitions based on groove gap waveguide (GGW) technology is presented in this paper with the goal to use these components in high-gain millimeter-wave antenna array design at 60-GHz frequency range. Since this GGW technology does not require electrical contact between the different metal layers of a complex 3-D waveguide structure, the fabrication cost and mechanical complexity are decreased. The designed T-junctions and different power dividers exhibit wide operational bandwidth and low output power and phase imbalance over the 60-GHz frequency band. Also, two transitions from GGW to a standard rectangular waveguide have been designed. To validate the performance of the designed components, a 64-way power divider in combination with 256 radiating slots is designed, prototyped, and measured at 60-GHz band. Measurement results agree well with the simulated performance of the complete array antenna, and the antenna gain is more than 32.5 dBi. The total radiation efficiency is more than 80% over the operating frequency range from 57 to 67 GHz. Also, the measured sidelobe levels are found to be agreeing well with the simulated level

A Ridge Gap Waveguide fed apperture-coupled microstrip antenna array for 60 GHz applications

This paper deals with the design of patch antenna arrays with Ridge Gap Waveguides (RGW) feed networks at 60-GHz band. An array of 64 radiating elements are designed and simulated to demonstrate the good performance of the proposed array. The proposed antenna shows the gain up to 22.6 dBi, efficiency higher than 80% and an impedance bandwidth of 13% covering 59-67 GHz. The results are valuable for the design and evaluation of wideband planar antenna arrays at millimeter-wave frequencies

Ridge gap waveguide slot antenna array with 30% bandwidth for 60-GHz applications

This paper presents a wideband high efficiency slot antenna array based on ridge gap waveguide technology at 60 GHz for millimeter-wave applications. The antenna sub-array consists of four radiating slots that are excited by a cavity. Some tuning pins are placed inside the cavity to achieve wideband performance. A 4 74 slots array antenna is designed using 4-ways power divider. The proposed structure exhibits 30% impedance bandwidth (|S11

A GapWaveguide-Fed Wideband Patch Antenna Array for 60-GHz Applications

This communication presents a wideband aperture-coupled patch antenna array based on ridge gap waveguide feed layer for 60-GHz applications. The novelty of this antenna lies in the combination of relatively new gap waveguide technology along with conventional patch antenna arrays allowing to achieve a wideband patch antenna array with high gain and high radiation efficiency. An 8 x 8-element array antenna is designed, fabricated, and tested. Experimental results show that the bandwidth of VSW

Investigating the thickness-effect of free-standing high aspect-ratio TiO2 nanotube layers on microwave-photoresponse using planar microwave resonators

One-dimensional TiO2 nanotube (TNT) layers are a promising candidate for UV detection due to their distinctive anisotropic geometry which is effective for light harvesting and rapid carrier transport. Here, the photosensitivity efficiency of TNT layers with various thicknesses of 15, 50, 80, and 110 mu m was utilized at a microwave frequency regime by modeling and experimentally. A planar microwave split ring resonator (PMSRR) was designed and fabricated to operate at -8 GHz to study TNT layers by monitoring the scattering parameter (S21) of the PMSRR under a constant UV irradiation power of -96.4 mu W/cm2. According to the results, the 80 mu m thick TNT layers demonstrated the highest resonant amplitude variation for the customized PMSRR. The change of the resonant amplitude was mainly attributed to the conductivity variation contributed by perturbation of trapped electron concentration, as the dominant factor under UV illumination, and their electromagnetic wave interaction. The main advantage of the proposed method of PMSRR for microwave photosensitivity monitoring over the conventional direct current (DC) conductivity measurements is to eliminate the effect of contact resistance between the TNT layers and metal electrodes utilizing the contactless aspect of wave interactions with the TNT layers at microwave regime to perform electrode-less measurements

Liposomes – metabolically active drug transport systems: visualization and pharmacokinetic. Part 2 (review)

Introduction. In the second part of the review we discussed aspects of visualization, pharmacokinetics and biodistribution of liposomes.Text. Many different methodsh as been proposed for the visualization of liposoms morphology and quality such as light microscopy, ESEM, TEM, AFM, etc. Each method have own advantages and limitations which are discussed in the article: In general, the selection of method depends on the specific morphological characteristics and level of details. It is important to understand the specificity of the liposomes and the visualization method for correct preparation of samples. Adequately performed pharmacokinetic and biodistribution studies can also be used as a tool for liposome visualization. The nature of active pharmaceutical ingredients, dose, lipid components, size of liposomes, charge, coating of liposomes with excipients and route of administration significantly affects the pharmacokinetics of liposomal forms. Additionally, the interaction of liposomal forms with the immune system, reticuloendothelial system and blood components play an important role in their absorption, distribution and elimination.Conclusion. The better understanding of the absorption, biodistribution, metabolism and clearance of liposomal formulations is essential for the development of modern drugs

Liposomes – metabolically active drug transport systems: classification, components, preparation methods, and stabilization. Part 1 (review)

Introduction. This review article is focused on the modern classification of liposomes, preparation methods, stabilization and the role of structural components, visualization, and pharmacokinetics. Part 1 discusses the first three aspects mentioned above.Text. Depending on the size and number of bilayers, liposomes are classified into simple, long-circulating, cationic, immuno-liposomes, and sterically stabilized. The lipid components of liposomes can have a pronounced effect on target organs and tissues. Metabolites of the main components of liposomes have their biological activity, depending on their combination and dosage. All of the above indicates the promise of using liposomes not only as carriers of drugs but also as independent effectors that can have a significant impact on human metabolism in various diseases. The advantages and limitations of methods for preparing liposomes, and the features for manufacturing stealth liposomes are discussed. A special section of the article is dedicated to liposome stabilization.Conclusions. The information discussed in the review article may be useful in the development of pharmaceutical formulations in liposomes. Liposomes are not only promising nanocontainers for targeted drug delivery, but also metabolically active complexes with a wide spectrum of activity

The Recent-Transmission of Mycobacterium tuberculosis Strains among Iranian and Afghan Relapse Cases: a DNA-fingerprinting using RFLP and spoligotyping

<p>Abstract</p> <p>Background</p> <p>Relapse of tuberculosis (TB) may develop as the result of reactivation of the endogenous primary infection, or as a result of a exogenous reinfection. This survey evaluated the rate of reactivation versus recent transmission among Iranian and Afghan relapse cases.</p> <p>Methods</p> <p>The sputum specimens were digested, examined microscopically for acid-fast bacilli, and inoculated into Löwenstein-Jensen slants by standard procedures. Thereafter, the susceptibility and identification tests were performed on culture positive specimens. Subsequently, the strains that were identified as <it>Mycobacterium tuberculosis </it>(258 isolates) were subjected to IS6110 restriction fragment length polymorphism (RFLP) and spoligotyping. Additional patient's information was collected for further epidemiological analysis. Patients whose isolates had identical genotyping patterns were considered a cluster with recent transmission episode.</p> <p>Results</p> <p>Out of 258 available isolates, 72(28%) had multi-drug resistant (MDR-TB) in ratio and 42 (16.2%) had other resistant. Notably, 38 of MDR-TB cases (52%) were isolated from Afghan patients. By IS6110-RFLP typing method, 65 patients (25%) were clustered in 29 clusters. In cluster cases, the intra-community transmissions between Iranian and Afghan patients were 41%. All MDR-TB patients in clusters had either Haarlem I or Beijing characteristic. The risk factors like sex, family history, close contact, living condition, PPD test result and site of TB infection were not associated with clustering. Although, the MDR-TB strains were more frequent in non-cluster cases (31%) than cluster one(18%) (P < 0.05). Majority of <it>M. tuberculosis </it>strains isolated from non-cluster cases were belong to EAI3 (51; 30%) and CASI(32;18.6%) superfamilies.</p> <p>Conclusion</p> <p>During the studied period, reactivation of a previous infection remain the more probable cause of recurrence. Although, the evidence of intra- community transmission between Iranian and Afghan TB cases, highlighted the impact of afghan immigrants in national tuberculosis control program (NTP) of Iran.</p