Features of the formation of the frequency of the microwave excitation signal in the quantum frequency standard on rubidium atoms - 87

The article discusses the main disadvantages of the current design of a quantum frequency standard based on rubidium-87 atoms. The main disadvantages of the current design of the quantum frequency standard on rubidium-87 atoms are considered. It is noted that the processes associated with light shifts in the optical part contribute to the greatest instability in the long-term operation of the quantum frequency standard. A solution is proposed to improve the design of the rubidium standard. A forecast for improving its metrological characteristics is presented. The results of experimental investigations are presented.

Aromatic Hydrazide Compounds That Inhibit the Growth of Mycobacterium tuberculosis

Aims: To demonstrate the efficacy of aromatic hydrazide compounds to inhibit growth of Mycobacterium tuberculosis. Study Design: To synthesize tuberculostats and test their antibacterial activity in-vitro. Place and Duration of Study: University of Nebraska, Durham Science Center, 6001 Dodge Street, Omaha NE 68182, and Texas A&M Health Science Center, Department of Microbial Pathogenesis and Immunology, 8447 State Hwy 47, Medical Research and Education Building, Room #3012, Bryan, TX 7780. From March 2019 to October 2019. Methodology: Hydrazide functional groups were formed by covalently bonding hydrazine onto a carbonyl carbon that is a substituent of a single aromatic ring. Microwave excitation was utilized for synthesis, followed by evaluation of antibacterial activity. These compounds were placed into tissue culture media at various concentrations and then Mycobacterium tuberculosis bacteria was added, in order to determine the level of growth inhibition. Growth inhibition of the bacteria was measured as a function of compound concentration versus growth inhibition. Results: Compounds A, B, C, and D carry hydrazide groups as a substituent to a single aromatic ring. All four compounds show zero violations of Rule of 5, indicating favorable drug-likeness. All four compounds showed greater than 50% growth inhibition of bacteria at concentrations below 50 micrograms per milliliter. Growth inhibition was measured by colony forming units and luminescence. Polar surface area, Log P, molecular volume, and other molecular properties were determined for these four compounds. Conclusion: These four hydrazide compounds induced substantial inhibition of bacterial growth. Microwave excitation for the synthesis of hydrazide compounds is effective. These compounds have favorable drug-likeness properties and are highly effective inhibiting the growth of Mycobacterium tuberculosis.

Design guidelines for transition metals as interstitial emitters in silicon nanocrystals to tune photoluminescence properties: zinc as biocompatible example

General photoluminescence design rules for interstitial transition-metal-doped silicon nanocrystals are derived; Zn shows excellent properties for medical imaging and plasmonic microwave excitation to exactly eliminate marked cells.

A HIGH-POWER SOURCE OF OPTICAL RADIATION WITH MICROWAVE EXCITATION

For more than 50 years, interest to the microwave heating technology has not weakened. In addition to the traditional areas of its application, which described in detail in [1], recently there has been an expansion of technological possibilities for the use of microwave energy associated with the impact of electromagnetic waves of the microwave range on various materials (sintering of metal and ceramic powders) and media, including plasma [2]. One such new direction is the creation of high-power and environmentally friendly sources of optical radiation on the basis of an electrodeless sulfur lamp with microwave excitation [2, 3]. The purpose of this paper is to the further development of the theory and practice of microwave excitation by the electrodeless sulfur lamps, improvement the energy efficiency during energy conversion into the optical radiation and widening the application of new light sources in real practice. The results of the computer modeling of conversion process of the microwave energy into optical radiation energy are presented. The simulation results are compared with experimental data. It is shown that additional use of the solar panels for the reverse conversion of the optical radiation into DC energy with follow-up its using in the circuits of secondary power supply allows improving the energy efficiency of the light source. References Microwave Power Engineering. Edited by E.C. Okress. V. 1, 2. Academic Press, New York & London. 1968.A.N. Didenko, SVCh-energetika. Teoriya i praktika. – Moscow: Nauka. 2003.- 445 s.G. Churyumov, T. Frolova, “Microwave Energy and Light Energy Transformation: Methods, Schemes and Designs. Microwave Energy and Light Energy Transformation: Methods, Schemes and Designs” // In book “Emerging Microwave Technologies in Industrial, Agricultural, Medical and Food Processing.” Edited by Kok Yeow You, IntechOpen, 2018. pp. 75-91.