Millimeter-Wave Donor-Acceptor-Doped DpHEMT Pashkovskii, Andrey B.; Bogdanov, Sergey A.; Bakarov, Askhat K. ...
IEEE transactions on electron devices,
2021-Jan., 2021-1-00, 20210101, Letnik:
68, Številka:
1
Journal Article
Recenzirano
In this article, we present GaAs millimeter-wave pseudomorphic high-electron-mobility transistor (pHEMT) using sophisticated AlGaAs-InGaAs-GaAs heterostructure with an In 0.22 Ga 0.78 As quantum well ...located inside an external quantum well formed by space charge regions in AlGaAs layers. In a heterostructure with this design, high mobility 5800 cm 2 /(<inline-formula> <tex-math notation="LaTeX">\text {V}\cdot \text {s} </tex-math></inline-formula>) and high density (<inline-formula> <tex-math notation="LaTeX">{4.7}\times {10}^{{12}} </tex-math></inline-formula> cm<inline-formula> <tex-math notation="LaTeX">^{-{2}} </tex-math></inline-formula>) of two-dimensional electron gas at 300 K were obtained. The localization of hot electrons in an external quantum well leads to an increase in their drift velocity and to enhance the dc and RF performances of the device. A field-effect transistor based on such a heterostructure with a T-gate of <inline-formula> <tex-math notation="LaTeX">0.14~\mu \text{m} </tex-math></inline-formula> in length shows a specific current density of about 0.7 A/mm, transconductance of about 250 mS/mm, gate-drain breakdown voltage in the range 23-31 V, which corresponds to more than 2 W/mm specific output RF power according to a simple estimate. The transistor demonstrates impressive RF characteristics, the maximum stable gain (MSG) of more than 15 dB at 40 GHz and more than 10 dB at 67 GHz, <inline-formula> <tex-math notation="LaTeX">{f}_{t} = {45} </tex-math></inline-formula> GHz and <inline-formula> <tex-math notation="LaTeX">{f} _{\text {max}} = {250} </tex-math></inline-formula> GHz. The MSG at 40 GHz increases with increasing distance between the gates in the drain and is almost constant in the range 25-55 GHz.
In this work we have considered metrological problems and measurement of magnetic parameters and presented methods of measuring effective magnetic anisotropy field
H
Aeff
and ferromagnetic resonance ...bandwidth ∆
H
in magnetically uniaxial hexagonal ferrites in the electromagnetic microwave working frequency range. The methods allow measuring
H
Aeff
in the 10–23 and 28–40 kE ranges and ∆
H
in the 0.5–5.0 range. One method (suitable for wavelength measurements in free space in the 3-mm wavelength range) has been implemented for the 78.33–118.1 GHz range. The other method (based on the use of microstrip transmission lines) has been implemented for the 25–67 GHz range.
The methods have been tested for polycrystalline specimens of hexagonal barium and strontium ferrites with nominal composition or complex substituted and having high magnetic texture. The measurement results have been compared with those obtained using conventional measurement methods and spherical specimens. Our methods prove to be highly accurate and reliable.
The issues of postal communication development in the Tambov governorate in the second half of the 19th – early 20th century are analyzed. The relevance of the study is determined by the significant ...role of information and communication infrastructure in the life of society and the state. The following methods were used: comparative-historical, statistical, historical-typological, analysis, synthesis. The research is based on a wide range of archival and published sources, in particular, on the materials of the State Archive of the Tambov region. A significant part of the archival materials used in the work is being introduced into scientific circulation for the first time. The development of urban and rural post offices, the organization of postal communication at the expense of the government and zemstvos, the management structure of postal and telegraph institutions are studied. It is concluded that during the period under study, the postal exchange among the people of the Tambov governorate significantly increased, the network of communication institutions expanded, and the revenues of the postal and telegraph department increased. In the Tambov governorate in the second half of the 19th – early 20th century, along with individual achievements in the development of postal communication, there were a number of unresolved problems, primarily in the functioning of rural mail. The study may be of interest to students of the history of communications, specialists working in the field of communications.
Aim: This work describes the activities of new-generation enzymatic preparations in fruit-berry substrates engineered for use in the fruit-wine industry. The enzymes were produced after genetic ...modification and selection of fungi Penicillium verruculosum, which produce efficient cellulase and pectinase enzymatic complexes.
Methods and results: This paper covers the main characteristics of novel multi-enzyme complexes and the results of in-lab fruit-wine production with addition of enzymatic preparations, which could be used on an industrial scale. The juice yield and the content of suspended materials in the enzymatically treated samples were compared. Experiments included the sensory analysis of produced juices and fruit wines.
Conclusion: Results show a significant increase in juice yield from the fruit pulp processed with the enzymatic preparations, without any negative effect on the quality and organoleptic attributes of the final product.
Significance and impact of the study: The obtained data clearly show that the use of the new-generation enzymatic preparations in the fruit-wine industry is effective.
In age groups from 20 to 60 years old, proliferation and differentiation of cells happen in a morphofunctional zone, in the electric field excited by 12 pairs of mother and daughter cells, turned out ...at cambial cells division. Thus in daughter cells the Src SH2 domain necessary both for cytoskeleton formation and tyrosinase activization is activated. If the conditions for strengthening of tyrosinase activity are created in organism, the portion of Src participating in the cytoskeleton building can decrease to critical level that will lead to development of a malignant tumor. If action of a stimulating factor is quite strong, proliferation of malignant cells begins at a stage of melanocyte, and a melanoma occurs. If action of factors is long and not strong, more remote descendants of daughter cells proliferate, and a cancer appears. In order that there will be a normal differen- tiation of malignantly changed daughter cells, it is necessary to block the tyrosinase. Thus all SH2 domains will go on cell cytoskeleton formation.
This article aimed to study geomorphological conditions of territory and estimation of its influence on the activity and hazard of karst evolution. Geomorphological conditions are considering from ...the position of next four factors: slope of relief, distance from river net, excess above the average water level in rivers, slope of basin. Relationships between these factors and karst forms were studied, using methods of mathematical statistics and correlation-regression analysis. In the result, were obtained integral distributions of karst form by values of studied factors and regression equations, which allows to prognosis karst hazard on the base of geomorphology of the area.
The role and importance of information and communication infrastructure in the modern world is growing, which increases the relevance of studying the history of the formation and development of ...postal, telegraph and telephone communications in Russia, primarily regional features of the social component of this process. Based on interdisciplinary approaches, involving a wide range of historical sources, the work explores the problems of the postal, telegraph and telephone service in the Tambov Governorate in the second half of the 19th – early 20th centuries. The issues of the number and staff of employees in communication institutions (post office, telegraph, telephone) of the Tambov Governorate are studied. We reveal the peculiarities and problems of the development of institutions staff of the postal and telegraph department. The problems of professional mobility of postal and telegraph employees are analyzed; the requirements for them, their official duties are described. In the second half of the 19th – early 20th century in the social and economic life of the Russian province, the information and communication component began to play a prominent role, which was reflected in the increase in the number of communica-tion institutions in the Tambov Governorate and employees in them. There were acute issues of human resourcing, first of all, qualified specialists. At the beginning of the 20th century the pro-portion of women who served in the institutions of the postal and telegraph department of the go-vernorate increased.
Proliferation and differentiation of cells occur in the morphofunctional zones, in the electric field excited by 12 pairs of mother and daughter cells, produced by cambial cell division. Thus, in the ...daughter cells, the Src SH2 domain is essential for both cytoskeleton formation and tyrosinase activation. If the conditions for strengthening the tyrosinase activity are created in an organism, the amount of the Src participating in the cytoskeleton construction process can decrease to a critical level, which will culminate in the development of a malignant tumor. If the action of a stimulating factor is strong enough, the malignant cells will begin to proliferate at the melanocyte stage, and a melanoma will be formed. If the action of the factors is long but not strong, only the more remote descendants of the daughter cells will proliferate, and a cancer will be formed. Therefore, to assure the normal differentiation of the malignantly changed daughter cells, the action of the tyrosinase needs to be blocked. Thus, all the SH2 domains are utilized in cell cytoskeleton construction.
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