Background. The subterahertz and terahertz frequency ranges are very promising for development of high speed wireless communications systems because of possibility to get the bandwidth about some tens of GHz, which provides the high channel capacity. However fast signal attenuation at its propagation in atmosphere complicate the operation of communications systems in these ranges. Aim. Use of fixed narrow-beam antennas with high antenna power gain allows to provide the direct surface communications distance to some kilometers. The communications distance limitation can be partially removed decreasing the frequency down to 200 GHz and narrowing the channel bandwidth down to some GHz. Methods. The model of transmitter-receiver system (200-220 GHz) based of modern semiconductor devices is described in the manuscript. Results. The possibility of digital signals transmission with speed up to 1 Gbit/s at the distance of 1 km is experimentally shown. Conclusion. According to calculations the output power of transmitter about some hundreds mW is enough for data transmission at the distance up to 1.5 km with antenna power gain of no less than 50 dB.
Significance. One of the modern trends in medical diagnostics is based on metabolomics, an approach allowing determination of metabolites which can be the specific features of disease. High-resolution gas spectroscopy allows investigation of the gas metabolite content of samples of biological origin. We present the elaboration of a method of studying diabetic and non-diabetic biological samples, prepared as pellets, by terahertz (THz) high-resolution spectroscopy.
Aim: The main idea of the work is studying the content of thermal decomposition gas products of diabetic and non-diabetic dried blood plasma and kidney tissues for revealing the set of gas-markers that characterized the diabetes by the THz high-resolution spectroscopy method.
Approach: We present an approach to study the diabetic and non-diabetic blood plasma (human and rats) and kidney tissues (rats), using high-resolution spectroscopy based on the non-stationary effect of THz frequency range. The methods of preparing the blood and kidney tissue samples as pellets and of vaporizing the samples were developed.
Results: The measurements of rotational absorption spectra of vapors at heating the pellets prepared from blood and kidney tissue were carried out in 118 to 178 GHz frequency range. The absorption lines appearing in spectra of the sample vapors were detected and identified. The molecular contents of thermal decomposition products differed for non-diabetic and diabetic samples; e.g., main marker is acetone appearing in the diabetic blood (human and rats) and in the diabetic kidney tissue.
Conclusions: Our paper illustrates the potential ability for determining the metabolite content of biological samples for diagnostics and prognosis of diseases for clinical medicine.
Significance: The creation of fundamentally new approaches to storing various biomaterial and estimation parameters, without irreversible loss of any biomaterial, is a pressing challenge in clinical practice. We present a technology for studying samples of diabetic and non-diabetic human blood plasma in the terahertz (THz) frequency range.
Aim: The main idea of our study is to propose a method for diagnosis and storing the samples of diabetic and non-diabetic human blood plasma and to study these samples in the THz frequency range.
Approach: Venous blood from patients with type 2 diabetes mellitus and conditionally healthy participants was collected. To limit the impact of water in the THz spectra, lyophilization of liquid samples and their pressing into a pellet were performed. These pellets were analyzed using THz time-domain spectroscopy. The differentiation between the THz spectral data was conducted using multivariate statistics to classify non-diabetic and diabetic groups’ spectra.
Results: We present the density-normalized absorption and refractive index for diabetic and non-diabetic pellets in the range 0.2 to 1.4 THz. Over the entire THz frequency range, the normalized index of refraction of diabetes pellets exceeds this indicator of non-diabetic pellet on average by 9% to 12%. The non-diabetic and diabetic groups of the THz spectra are spatially separated in the principal component space.
Conclusion: We illustrate the potential ability in clinical medicine to construct a predictive rule by supervised learning algorithms after collecting enough experimental data.
We apply a hybrid nonequilibrium Green’s functions and relaxation rate approximation approach to investigate frequency multiplication in the gigahertz to terahertz range delivering results in good agreement with experimental data for different input frequencies. A discussion of the current limitation of housing designs for the superlattices is given, based on a simple model for the local electric field and in comparison with measured input powers delivered by a backward wave oscillator.
Backward Wave Oscillators (BWO) are frequently used as sources of mm- and sub-mm-wavelengthradiation in microwave spectroscopy. They can easily be tuned to any frequency in a broad frequencyband. However, an oscillator without any stabilisation unit has a relatively broad spectrum and the longterm stability is bad as well.
Nowadays the development of analytical spectroscopy with high performance, sensitivity and spectral resolution for exhaled breath research is attended. The method of two-frequency high precise THz spectroscopy and the method of high precise subTHz-THz-IR spectroscopy are presented. Development of a subTHz-THz-IR gas analyzer increases the number of gases that can be identified and the reliability of the detection by confirming the signature in both THz and MIR ranges. The testing measurements have testified this new direction of analytical spectroscopy to open widespread trends of its using for various problems of medicine and biology. First of all, there are laboratory investigations of the processes in exhaled breath and studying of their dynamics. Besides, the methods presented can be applied for detecting intermediate and short time living products of reactions in exhaled breath. The spectrometers have been employed for investigations of acetone, methanol and ethanol in the breath samples of healthy volunteers and diabetes patients. The results have demonstrated an increased concentration of acetone in breath of diabetes patients. The dynamic of changing the acetone concentration before and after taking the medicines is discovered. The potential markers of pre-cancer states and oncological diseases of gastrointestinal tract organs have been detected. The changes in the NO concentration in exhaled breath of cancer patients during radiotherapy as well as increase of the NH3 concentration at gastrointestinal diseases have been revealed. The preliminary investigations of biomarkers in three frequency ranges have demonstrated the advantages of the multifrequency high precise spectroscopy for noninvasive medical diagnostics.
Valery Koshelets, Andrey Ermakov, Lyudmila Filippenko, Nickolay Kinev, Oleg Kiselev, Mikhail Torgashin, Arno de Lange, Gert de Lange, Sergey Pripolzin, Vladimir Vaks
A Superconducting Integrated Receiver (SIR) comprises on one chip all elements needed for heterodyne detection: a
low-noise SIS mixer with quasioptical antenna, a Flux-Flow Oscillator (FFO) acting as a Local Oscillator (LO) and a
second SIS harmonic mixer (HM) for the FFO phase locking. Light weight and low power consumption combined with
nearly quantum limited sensitivity and a wide tuning range of the FFO make SIR a perfect candidate for many practical
applications. In particular, the SIR developed for novel balloon borne instrument TELIS (TErahertz and submillimeter
LImb Sounder) covers frequency range 480 - 650 GHz. As a result of recent receiver's optimization the DSB noise
temperature was measured as low as 120 K for the SIR with intermediate frequency (IF) band 4 - 8 GHz. The capability of
the SIR for high resolution atmospheric spectroscopy has been successfully proven with scientific balloon flights from Kiruna, North
Sweden. Diurnal cycles of ClO and BrO has been observed with BrO line level of only about 0.5 K. Possibility to use the
SIRs for analysis of the breathed out air at medical survey has been demonstrated.
Cyclotron resonance of 2D holes in high-mobility undoped multi-quantum-well Ge/GeSi heterostructure has been studied in both 'classical' and quantizing magnetic fields. Effects of hole heating on 2D hole cyclotron resonance has been investigated. The calculations of 2D hole Landau levels in rectangular quantum well have been performed allowing to interpret the evolution of CR spectra in going from 'classical' to 'quantum' range.
The noise generator based on the backward wave oscillator (BWO) in 370-535 GHz frequency range has been constructed. The noise spectrum width can be varied from 1 GHz to entire BWO range of operation. The maximum noise temperature is not less than i09 K.
Backward Wave Oscillators (BWO's) are used as the radiation source of themicrowave-synthesisers. They work in a frequency-range from 3 7GHz to 3 SOGElz,They can be used as programmable generators with hi el accuracy or noisegenerators. In the first case, a short-time stability of 6*10-9, a Ion.7.--time stability of10-8 and a accuracy of frequency of 10-8 is reached. The noise generator has anoise-bandwidth of 10Gliz with a equivalent noise-temperature of about 1010K_
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