Dose effects of ultraviolet and terahertz laser radiation on the plasma membrane of erythrocytes

Chronic exposure of adult rats to dietary intake of cadmium (15 mg CdCl2/day/kg for 30 days) leads to development of anemia and thrombocytosis. Anemia is characterized by significant reticulocytosis (13.1 +/- 1.0%), anysocytosis, poikilocytosis, iron deficiency and marked alterations of antioxidant and metabolic status of red blood cells. Activities of SOD, catalase, GPx and GR were significantly increased in red blood cells of cadmium-treated rats. In treated animals cadmium induced an increase of red cell reduced and oxidized glutathione with no changes of GSSG/GSH ratio. However, significant reduction of lipid peroxidation was found. Plasma levels of tocopherol and ascorbate, as well as activity of glutathione-S-transferase, were all significantly increased in cadmium-treated rats. The energy metabolism of red blood cells was deeply altered in cadmium-treated rats. The levels of ATP, ADP, AMP and TAN were significantly increased while ATP/ADP ratio and adenylate energy charge (AEC) were significantly reduced. The level of 2,3-BPG was somewhat lower, but 2,3-BPG/Hb ratio was considerably higher, in red blood cells of cadmium-treated rats.

Objective: To identify the clinical and pathogenetic significance of the activation of lipid peroxidation processes in brucellosis. Materials and methods: There were examined235 patients with brucellosis at age of 15 to 72 years.The content of primary products of lipid peroxidation in the blood serum of patients with acute, subacute and chronic brucellosis was studied. Results: It was established that in all groups of patients with brucellosis, a moderate excess of the concentration of malonic dialdehyde in the serum of the blood of patients with brucellosis was observed at the 2nd week of the disease, followed by a decrease at the 3rd week.Maximum concentrations of malonic dialdehydewere observed in patients with acute brucellosis during all periods of the disease compared with patients with subacute and chronic brucellosis. Consequently: It has been established that the determination of only primary products of lipid peroxidation in the blood serum of patients with brucellosis does not allow to fully controlling the course of lipid peroxidation.It is advisable to evaluate the intensity of lipid peroxidation in a complex, taking into account the accumulation of the final degradation products of hydroperoxides in the blood serum.

We designed and fabricated beam steering subwavelength grating (BS-SWG) with high efficiency, wide angles, and broadband beam steering in the terahertz (THz) range. Beam steering technology in the THz range by a fixed structure and frequency sweep has to date lacked a device combining high efficiency and a wide beam steering angle. A subwavelength structure using float zone Si, a low-loss dielectric, could combine both of these aspects, but no experimental demonstration in the THz range has been performed to our knowledge. The BS-SWG was designed with an efficiency of 0.708 at 0.4 THz and beam steering angles of -72.1°--34.8° by sweeping the incident frequency from 0.3 THz to 0.5 THz including the Beyond 5 G/6 G communication bands. An efficiency of 0.354 at 0.400 THz and beam steering angles of -74°--34° were experimentally achieved, demonstrating the potential of high-efficiency, wide-angle beam steering for THz communications, imaging, and radar applications.

The aim of this scientific research is to study the effect of electromagnetic waves of the terahertz range on the frequency of molecular oxygen (129.0 GHz) on the processes of lipid peroxidation in experimental animals under chronic stress. Overtraining is a psychological and/or physiological condition that manifests itself as impairment in athletic performance. This condition may be based on prolonged competitive stress and stressful psychological factors that can lead to the activation of lipid peroxidation processes (LPO). Moreover, the activation of the processes of lipoperoxidation is the main pathogenetic link of many socially significant diseases, especially cardiovascular disease. These circumstances require the development of modern and relevant methods of prevention and treatment of post-stress disorders. In the last ten years, a new method has been used to assess the effect of stress on the pro-oxidant activity of blood plasma and the concentration of antioxidants by exposure to electromagnetic radiation. In this paper electromagnetic waves of terahertz range, at frequencies of active cellular metabolites, were used to correct the processes of lipoperoxidation (LPO) changes at chronic stress. The innovative device "Оrbit" was used to emit Terahertz (THz) radiation at frequencies of molecular oxygen 129,0 GHz in fractional mode. From the marked activation of lipid peroxidation processes and inhibition of antioxidant activity of blood, it is possible to observe a partial normalization, in the conditions of long-term immobilization or through cold water swimming of animals (rats), by using THz waves 5 days for 15 minutes; moreover, if the same procedure was applied for 30 minutes, a complete normalization of lipid peroxidation and antioxidant levels in the blood of stressed animals occurred. The study shows the high efficiency and expediency of using the device for terahertz therapy "Orbit" in the correction of altered processes of lipid peroxidation and it encourages future application for humans. DOI: https://doi.org/10.52783/pst.289

We investigated the optical properties of zinc germanium phosphide (ZnGeP2 or ZGP) crystals in a wide terahertz (THz) range from 0.2 THz to 6 THz, and made comparisons between crystals grown by both horizontal gradient freezing (HGF) and vertical gradient freezing (VGF) techniques. THz time-domain spectroscopy (TDS) and Fourier transform infrared spectroscopy (FTIR) systems were used to measure and analyze the transmittance, refractive indices and absorption coefficients. It was found that the HGF grown crystals have different birefringence and absorption in the THz range compared with the VGF grown crystals. The anisotropic absorption in the THz range was observed and the polar phonon modes at 3.6 THz and 4.26 THz were also discussed. The dispersion and absorption data of ZGP given in this report enabled us to know it better in the THz range and optimize its THz applications.

The terahertz (THz) range of frequencies is borderline between microwave electronics and photonics. It corresponds to the frequency bands of molecular and lattice vibrations in gases, fluids, and solids. The importance of the THz range is in part due to numerous potential and emerging applications which include imaging and characterization, detection of hazardous substances, environmental monitoring, radio astronomy, covert inter-satellite communications, as well as biological and medical applications.During the last decades marked progress has been achieved in the development, fabrication, and practical implementation of THz devices and systems. This is primarily owing to the utilization of gaseous and free electron lasers and frequency converters using nonlinear optical phenomena as sources of THz radiation. However, such devices and hence the systems based on them are fairly cumbersome. This continuously stimulates an extensive search for new compact and efficient THz sources based on semiconductor heterostructures. Despite tremendous efforts lasting several decades, the so-called THz gap unbridged by semiconductor heterostructure electron and optoelectron devices still exists providing appropriate levels of power of the generated THz radiation. The invention and realization of quantum cascade lasers made of multiple quantum-well heterostructures already resulted in the partial solution of the problem in question, namely, in the successful coverage of the high-frequency portion of the THz gap (2–3 THz and higher). Further advancement to lower frequencies meets, perhaps, fundamental difficulties. All this necessitates further extensive theoretical and experimental studies of more or less traditional and novel semiconductor heterostructures as a basis for sources of THz radiation.This special issue includes 11 excellent original papers submitted by several research teams representing 14 institutions in Europe, America, and Asia. Several device concepts which appear to be feasible for the realization of novel THz devices are put forward and discussed in this collection of experimental and theoretical papers.The issue starts with a paper by Akis et al which deals with a theoretical study of the operation of high electron mobility transistors at THz frequencies. For this, the authors use the numerical simulations using a full-band, cellular Monte Carlo transport model coupled to a full Poisson equation solver.The next three papers by Reklaitis, Balocco et al , and Mikhailov and Zieglel are devoted to considering new ideas related to frequency multiplication which can lead to the up-conversion of ac signals to THz frequencies. For this purpose, different concepts of the devices based on nontrivial heterostructures and materials are proposed and studied.The paper by Knap et al provides an overview of the authors experimental results on the plasma effects infield effect transistors. These effects can be used for the resonant detection of THz radiation and its emission. The observed THz emission from more complex device structures, namely, dual grating gate heterostrucures, which is attributed to the self-excitation of plasma waves, is discussed by Otsuji and his co-workers.The following two papers (by Ryzhii et al and Popov et al) deal with the development of device models and using the one which could explain the results of experimental observations described in the paper by Otsuji et al . In both these papers, the mechanisms of plasma wave instability in spatially periodic heterostructures are analyzed.In the paper by Starikov and his colleagues, an idea to utilize the transit-time resonance assisted by optical phonon emissionis revived and revisited. As demonstrated, this mechanism in the electron system in nitride-made heterostructures can lead to negative dynamic conductivity in the THz range of frequencies and, hence, be used for the generation of THz radiation.In the paper by Millithaler et al, Monte Carlo simulations are used to study the voltage fluctuationsaffected by the plasma oscillations in two-terminal heterostructures with an n-type InGaAs channel.Finally, the paper by Liu {\\it et al} is devoted to the concept of quantum cascade THz lasers using resonant tunneling in quantum dot systems instead of the standard multiple quantum well heterostructures.I would like to express my deep gratitude to all of the authors for having submitted high-quality papers. I am confident that this special issue will substantially promote further progress in THz technology.

PurposeThe proposed structure consists of copper as a ground plane and 50 µm polyimide dielectric layer is placed in between the ground panel and top radiating patch. Octagon and pentagon shapes are combined to form a unit cell. This structure exhibits seven absorption peaks within the short frequency range 0.3–0.5 terahertz (THz) without any interference. Under normal incidence, this structure achieves the absorption of 96.9%, 95.3%, 98.7%, 91.7%, 96.5%, 95% and 97.8% at 0.3136 THz, 0.377 THz, 0.4060 THz, 0.4085 THz, 0.4240 THz, 0.4436 THz and 0.4648 THz, respectively. This study aims to provide a range of applications in THz dielectric sensing, thickness sensing, communications, wavelength selective radiation and detecting.Design/methodology/approachMulti-band THz metamaterial absorbers (MMA) from previous research are having a large unit size because of the presence of stacked layers and multiple resonators within a single unit cell. This leads to difficulty while implementing in practical applications. In this study, a new MMA has been presented at seven distinct frequencies without using stacked layers and multiple resonators.FindingsThis structure exhibits seven absorption peaks within the short frequency range 0.3–0.5 THz without any interference. Under normal incidence this structure achieves the absorption of 96.9%, 95.3%, 98.7%, 91.7%, 96.5%, 95% and 97.8% at 0.3136 THz, 0.377 THz, 0.4060 THz, 0.4085 THz, 0.4240 THz, 0.4436 THz and 0.4648 THz, respectively. The polarization and angle insensitivity of the design have been validated by numerical simulation up to 90° of oblique incidence. The effects of variation in geometrical parameters on absorption response are demonstrated. The physical mechanism of the structure is analysed by electric and magnetic field distributions. The resonant frequency ranges and the number of bands in this work are compared with previously reported papers. In THz range, this is the first time a single planar structure provides seven-band high-level absorption performance.Originality/valueThe highlights of the proposed seven-band THz MMA structure, in comparison with previous THz metamaterials, are as follows: this has a simple unit-cell structure and high resonant mechanism within the short frequency range 0.3–0.5 THz; this MMA can provide seven-band high-level absorption performance in a single planar structure for the first time in THz range; and this structure is polarization and incident angle independent in nature.

The development of efficient and reliable sensors operating at room temperature is essential to advance the application of terahertz (THz) science and technology. Pyroelectric THz detectors are among the best candidates, taking into account their variety, outstanding performance, ease of fabrication, and robustness. In this work, we compare the performance of six different detectors, based on either LaTiO3 crystal or different polymeric films, using monochromatic radiation of the Novosibirsk Free Electron Laser facility (NovoFEL) in the frequency range of 0.9-2.0 THz. The main characteristics, including noise equivalent power and frequency response, were determined for all of them. Possible reasons for the differences in the obtained characteristics are discussed on the basis of the main physicochemical characteristics and optical properties of the sensitive area. At least three detectors showed sufficient sensitivity to monitor the shape and duration of the THz macropulses utilizing only a small fraction of the THz radiation from the primary beam. This capability is crucial for accurate characterization of THz radiation during the main experiment at various specialized endstations at synchrotrons and free electron lasers. As an example of such characterization, the typical stability of the average NovoFEL radiation power at the beamline of the electron paramagnetic resonance endstation was investigated.

Exposure of cells or biological tissues to high-power pulses of terahertz (THz) radiation leads to changes in a variety of intracellular processes. However, the role of heating effects due to strong absorption of THz radiation by water molecules still stays unclear. In this study, we performed numerical modelling in order to estimate the thermal impact on water of a single THz pulse as well as a series of THz pulses. A finite-element (FE) model that provides numerical solutions for the heat conduction equation is employed to compute the temperature increase. A simple expression for temperature estimation in the center of the spot of THz radiation is presented for given frequency and fluence of the THz pulse. It has been demonstrated that thermal effect is determined by either the average power of radiation or by the fluence of a single THz pulse depending on pulse repetition rate. Human dermal fibroblasts have been exposed to THz pulses (with an energy of 15,upmu hbox {J} and repetition rate of 100 Hz) to estimate the thermal effect. Analysis of heat shock proteins expression has demonstrated no statistically significant difference (p < 0.05) between control and experimental groups after 3 h of irradiation.

The spectral range lying from microwaves to optical spectrum was known as the “terahertz (THz) gap” due to the lack of efficient sources and detectors in this spectral region up to the 90 ‘s. This had prevented any use of THz radiation particularly useful in spectroscopy since vibrational modes of molecules are involved in the THz range. THz spectroscopy provides therefore unique fingerprints of material of great interest (e.g. explosives, pharmaceuticals, drugs …) for security and medical applications. Since the emerging of femtosecond pulsed lasers, this gap has been filling by scientists and industrials. Time resolved spectroscopy setups historically used in THz range 1 take advantage of non-linear effects in crystals and semiconductors to generate and detect THz using laser pulse. Such techniques provide picosecond electromagnetic bursts whose spectrum are limited and spread typically from 0.1 THz to few THz. Indeed, photoconductive antennas based on semiconductors have limited bandwidths due to photo-carrier lifetime, while electro-optic (EO) crystals absorb a part of the generated THz leading to dips in the available THz spectrum. The use of diluted media as gases could therefore leads to larger bandwidth. The first solution was proposed by Dai et al.2 who used plasma as a centro-symmetric nonlinear media for broadband THz generation and detection. This technique offers the possibility to get THz waves 1 to 2 orders of magnitude more powerful than classical methods. It also gives the possibility to get a very broadband spectrum, from 0.1 THz to several tens of THz. To generate such broadband THz radiation, a high power femtosecond laser pulse is focalized in air until breakdown is reached: a plasma is generated. The electrons produced by this ionization process are accelerated by an intense optical field asymmetry. This asymmetry is enhanced by using part of the optical pulse whose frequency was previously doubled in a non-linear crystal. The same principle is used to detect the THz signal. In this configuration, the plasma acts as a non linear medium where a four wave mixing occurs: 2 photons from the optical pulse at pulsation ω and 1 THz photon mix to generate a photon at pulsation 2ω whose intensity is directly proportional to THz signal intensity. The authors will present during the conference, short THz waveforms and their associated broadband spectrum generated and detected by air plasma techniques, and their dependence on the experimental parameters.

As the communication band gradually approaches the terahertz (THz) range, there is an urgent need to explore materials with ideal dielectric properties for THz communication devices. Nevertheless, most polymers present a low dielectric constant (Dk), and the regulation of their dielectric properties in the THz range has rarely been reported. In this work, the isotactic polypropylene (iPP)/α-Al2O3 whisker composites were synthesized and their THz dielectric parameters were optimized. The Dk values increased from 2.23 to 3.13 with filler (α-Al2O3 whisker) concentration, ranging from 0 to 20 vol%, but were almost independent of the test frequency. The loss tangent (Df) values presented an increasing tendency along with both filler concentrations and test frequency. All composites exhibited Df values of less than 4.0 × 10−3. Particularly, the dielectric properties of composites can be further regulated by adjusting the orientation direction of the whisker fillers. The orientation of the whisker fillers was adjusted via the injection molding method. Along the direction of the whisker orientation distribution, the composites exhibit higher Dk values and lower Df values. This work presented a schematic to design polymer composites with higher Dk but controlled Df in the THz range and is significant for the development of advanced materials-based THz devices.

Resonant frequencies of the two‐dimensional plasma in field effect transistors (FETs) increase with the reduction of the channel dimensions and can reach the terahertz (THz) range for micrometer and sub‐micrometer channel lengths. Nonlinearity of the gated electron gas in the transistor channel can be used for the detection of THz radiation. The possibility of tuneable narrow band detection in sub‐THz and THz range, related to plasma resonances, has been demonstrated for nanometre gate length transistors at cryogenic temperatures. At room temperatures the plasma oscillations are usually strongly damped, but field effect transistors can still operate as an efficient broadband detectors in the THz range. We present an overview of experimental results on THz detection by field effect transistors made of III‐V and Si materials, The material issue is discussed and first room applications of FETs for imaging at frequencies above 1 THz are demonstrated. (© 2009 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Broadband multimodal THz waveguides for efficient transfer of high-power radiation in space-confined conditions

Terahertz (THz) range holds between infrared light and millimeter wave or microwave radiation. Moreover, THz waves is highly attenuated by the metal object or sensitive to an inter-molecular binding force. Therefore, imaging using THz range is attracted much attention for security, manufacturing, chemical imaging, and so on. In our research, the THz detector composed of Indium arsenide (InAs) high electron mobility transistor (HEMT) and one-sided directional slot antenna on a chip will be developed. In this paper, we focused on the antenna on a chip. The proposed antenna has three layers, namely, top antenna metal, dielectric substrate (BCB, benzocyclobutene) and bottom floating metal layer. There are a coplanar (CPW) feed lines and slots on the top antenna metal. By optimizing the size of the bottom floating metal layer, the radiation toward the back side is suppressed. The CPW feed line is connected the gate electrode on the InAs HEMT. In order to maximize the receiving THz signal form the antenna to InAs HEMT, antenna and gate input impedance is characterized by using the 3D electromagnetic simulator. It has been found that when the input impedance of the gate electrode changes from 10 ohms to 50 ohms, the voltage generated at the gate electrodes is tripled. The antenna was fabricated by the conventional photolithography process. The size of the radiation metal is 290 μm x 210 μm on the top metal with probe pads. The measured antenna gain is 5.57 dBi at 0.93 THz compared with the 5.96 dBi antenna gain at 1 THz from the simulation.

Terahertz (THz) technology developed rapidly in recent years. Liquid crystals (LCs) are one of the most promising base materials to construct switchable devices in THz range because of their high optical anisotropies. However, the practical applications of the devices are hampered by the relationships between birefringence, thickness and LCs switching time. Due to the long wavelength, THz device requires a larger birefringence LC than the device operated at optical frequencies. Yet, in order to design an efficient switchable LC-THz device, it is crucial to find or synthetize LC material which will still display a useful birefringence at THz frequencies. The birefringence properties of LC are determined by the molecular polarizability of the relevant material. Knowledge of the LC molecular polarizability and its dependence on the molecular structure is important for designing LC molecules with desired THz properties. The prediction of the photoelectric characteristics could save a considerable quantity of the man-power and materials needed for the design or synthesis of new LC compounds. A priori screening of materials and the prediction of the optoelectronic properties would make a vast opportunity for expanding the LC material application scope. Hence, the main purpose of the present work is to provide a theoretical method of calculating and analyzing the THz polarizability properties of LC single compounds for LC-THz device applications. In this work, the frequency dependent molecule polarizability values of liquid crystal PCH5, 5CB and 5OCB in THz range are calculated by the density functional theory method. The geometries of the studied LCs are optimized at B3 LYP levels with the standard 6-311G(d) basis set. From the optimized geometries the molecule THz polarizabilities of LCs are calculated by the M06-2x functional with 6-311++G(2d, p) basis set, and they are found to be in good agreement with experimental data. By plotting the polarizability density analysis (PDA), the spatial contributions of electrons to the longitudinal polarizability are presented. The influences of alkyl chain and core structure on the microscopic polarizability of the LC molecule are investigated and explained by using the finite field approach and PDA. The results show that the unsaturated group, such as benzene ring or cyanobenzyl, makes great contribution to the polarizability of LC. In the design process, the new type of LC molecule must be extended the length of up electron conjugated system, to reduce the energy gap between HOMO and LUMO, and hence improving LC molecule polarizabilty. We hope that the present work could give a useful guide in screening or designing LC molecules for THz applications, and offer an effective way to understand fundamental optoelectronic characteristic of LC materials in the THz frequency range.