Real-time wide dynamic range spectrometer using a rapidly wavelength-switchable terahertz parametric source

In this study, we demonstrate real-time terahertz (THz) spectroscopy using a rapidly wavelength-switchable injection-seeded THz parametric generator. We developed a wavelength-switchable external cavity diode laser using a digital micromirror device as a seed source for the generator. We realized fast acquisition of THz spectra by switching the wavelength of the laser for each pump beam pulse. This system can rapidly switch wavelengths and easily increase the number of measurement wavelengths, and it also has a wide dynamic range, of more than 75 dB, and high stability. Furthermore, by combining this system with THz parametric detection, all wavelengths can be detected in a single frame using a near infrared camera for real-time reagent measurement.journal articl

Noise-free terahertz-wave parametric generator

We achieved noise-free terahertz (THz)-wave output from an injection-seeded THz-wave parametric generator (is-TPG) employing high-power injection seeding. A conventional is-TPG uses a weak continuous-wave (CW) seed beam. The position in which broadband noise is generated (via spontaneous parametric down-conversion) and the position of the THz signal overlap. Thus, the output features broadband TPG noise, reducing the signal-to-noise ratio. To solve this problem, we shifted the position in which the THz signal is generated to the front of the crystal; we separated the signal from broadband TPG noise using a high-powered, pulsed seed beam that was 107-fold more powerful than the CW seed beam. Thus, we extracted only the THz signal; we achieved a noise-free is-TPG. This system features a signal-to-noise ratio of 95 dB, approximately 40 dB better than the signal-to-noise ratio of the conventional system.journal articl

Terahertz Parametric Generators and Detectors for Nondestructive Testing Through High-Attenuation Packaging Materials

Here, we introduce an injection-seeded terahertz (THz)-wave parametric generator (is-TPG) spectroscopic system and its application to nondestructive inspection through a packaging material with high attenuation. Recent technological innovations have dramatically improved is-TPG output. Combined with THz parametric detection, whereby detection is performed in the reverse process of generation, a spectrometer with an extremely high dynamic range has been achieved. THz spectroscopic imaging has enabled the previously difficult visualization of substance spatial distributions, even through thick packaging materials. Moreover, the introduction of machine learning has improved the accuracy of identification. High-speed wavelength tuning and multi-wavelength generation enable real-time acquisition of sample information and real-time identification by image recognition, thus broadening the range of applicability of the is-TPG. Additionally, detection sensitivity has improved to a level of < 1 aJ through multi-stage THz parametric detection. The system combining is-TPG and THz parametric detection now exhibits a dynamic range of 125 dB, enabling imaging through thick, high scattering materials with an attenuation factor of −100 dB; to our knowledge, such measurements are difficult to achieve with other THz-wave systems.journal articl

Endoscopic Activity and Serum TNF-α Level at Baseline Are Associated With Clinical Response to Ustekinumab in Crohn’s Disease Patients

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Pulse Burst Multiwavelength Terahertz-Wave Spectroscopic Measurement Using Parametric Wavelength Conversion

In this study, we developed a multiwavelength spectroscopic measurement system using a pulse burst-pumped injection-seeded terahertz (THz)-wave parametric generator (is-TPG). Real-time spectroscopy using multiwavelength simultaneous generation has been demonstrated; however, the ability to make quantitative measurements with this method has been limited by the gain competition between wavelengths. In this study, we divided the pump beam into multiple paths and created pulse bursts with nanosecond intervals via spatial delays. Quasi-multiwavelength simultaneous generation was achieved by generating different THz wavelengths with each pulse; in principle, this is equal to repetitive single-wavelength generation. The gain competition between multi-wavelengths was suppressed compared to the multiwavelength is-TPG pumped by a single-pump pulse. Pulse-burst pumping improved the “quantitativeness” of real-time spectroscopic measurements using an is-TPG and is expected to expand the scope of THz wave applications.journal articl

Expansion of the tuning range of injection-seeded terahertz-wave parametric generator up to 5 THz

In this paper, we report the improvement of the frequency tuning range of an injection-seeded terahertz (THz)-wave parametric generator (is-TPG). A significant previous limitation was the high absorption coefficient in the higher-frequency region of a MgO:LiNbO3 crystal. Here, we inclined the crystal slightly, so that a fraction of the pump beam was internally reflected at the THz-wave exit surface of the crystal. In this configuration, it was easier for a higher-frequency THz wave to reach the crystal surface, because the center core region of the pump beam was closer to the exit surface. As a result, the upper limit of the frequency tuning range increased from 3.0 to 5.0 THz.journal articl

Interações entre bactérias diazotróficas e fungo micorrízico em genótipos de milho

Some diazotrophic bacteria can fix nitrogen biologically in gramineous host plants. Generally, gramineous plants are also associated with mycorrhizal fungi, that can improve mainly plant P uptake. Among the factors affecting plant-microbe interactions, the plant genotype plays an important role. This study evaluates the effect of diazotrophic bacteria and an arbuscular mycorrhizal fungus (AMF), on five genotypes of maize (Zea mays L.), in relation to plant biomass, shoot N and P concentrations, and fine root morphological traits. The experimental design was entirely randomized in a factorial 5 × 4 × 2 arrangement, i.e., five maize genotypes (hybrids C333B, AS3466, and PREMIUM, and the inbreed lines lg40897-1 and lg40505-1), three diazotrophic bacteria (Azospirillum lipoferum, A. amazonense, and Burkholderia sp.) in addition to a control without bacterial inoculation, co-inoculated or not with the AMF Glomus clarum. The non-mycorrhizal plants inoculated with Azospirillum exhibited the highest N concentrations. The lines lg40897-1 and lg40505-1 showed higher P concentrations as compared to the hybrids, mainly when colonized by AMF. The higher levels of mycorrhizal colonization (90%) occurred in the C333B and lg40897-1 genotypes, which also exhibited a greater root diameter. Mycorrhiza increased shoot and root biomass, besides root traits as total length, specific length, total surface, and incidence of root hairs in all genotypes. In addition, mycorrhiza also stimulated the root colonization by diazotrophic bacteria. The bacteria did not affect root morphological traits and mycorrhizal colonization.Algumas bactérias diazotróficas podem fixar N biologicamente em gramíneas, as quais se associam a fungos micorrízicos, o que pode levar a um aumento principalmente da absorção de P. Dentre os fatores que afetam as interações planta-microrganismos, o genótipo da planta tem importante papel. Esse trabalho avalia o efeito de bactérias diazotróficas e de um fungo micorrízico arbuscular (FMA) em cinco genótipos de milho (Zea mays L.), em relação à biomassa das plantas, teores de N e P na parte aérea e parâmetros relacionados à morfologia das raízes finas. O delineamento experimental foi inteiramente casualizado, em arranjo fatorial 5 × 4 × 2, sendo cinco genótipos de milho (híbridos C333B, AS3466, PREMIUM e as linhagens lg40897-1 e lg40505-1), três bactérias diazotróficas (Azospirillum lipoferum, A. amazonense e Burkholderia sp.), mais um controle sem bactéria, co-inoculadas ou não com o FMA Glomus clarum. As plantas sem FMA e inoculadas com Azospirillum apresentaram os maiores teores de N. As linhagens lg40897-1 e lg40505-1 apresentaram maior concentração de P em relação aos híbridos, principalmente quando micorrizadas. Os maiores níveis de colonização micorrízica (90%) ocorreram nos genótipos C333B e lg40897-1 que, por sua vez, apresentaram maior diâmetro de raízes. O FMA aumentou a biomassa da parte aérea e das raízes, comprimento total e específico, superfície total e incidência de pêlos nas raízes em todos os genótipos. O fungo micorrízico também estimulou a colonização das raízes pelas bactérias diazotróficas. Já as bactérias não alteraram as características morfológicas das raízes e nem a colonização micorrízica