Search Results (67)

To obtain a flat top shaped passband in a conventional thin-film-based optical bandpass filter (OBF), it needs a large number of constitutional layers of thin films, which makes the film deposition systems more complicated and accumulates errors in film growth. A flat top and polarization-independent optical bandpass filter structure is proposed based on experimentally verified polarization independency in the form of a prism-pair coupled planar optical waveguide (POW). The POW is composed of two waveguide stacks, which consists of nine planar thin-film layers. Theoretical simulations show that the flat band top spans about 5 nm with transmittance over 97.8%. The passband is designed to be centered at 632.8 nm, the He-Ne laser wavelength, and the FWHM (full width at half maximum) bandwidth is about 35 nm. Within 0.5° tuning for the incident angle of the light, the passband could be shifted within 50 nm, while its transmittance fluctuates only less than 1% and the passband shape distorts only slightly. This type of OBF is potentially applicable in various fields of optical and laser spectroscopies. Full article

Motivated by two of the most unexpected discoveries in recent years—the detection of ArH⁺ and ${\mathrm{HeH}}^{+}$ noble gas molecules in the cold, low-pressure regions of the Universe—we investigate [He₂H]⁺ and [Ne₂H]⁺ as potentially detectable species in the interstellar medium, providing new insights into their energetic and spectral properties. These findings are crucial for advancing our understanding of noble gas chemistry in astrophysical environments. To achieve this, we employed a data-driven approach to construct a high-accuracy machine-learning potential energy surface using the reproducing kernel Hilbert space method. Training and testing datasets are generated via high-level CCSD(T)/CBS[56] quantum chemistry computations, followed by a rigorous validation protocol to ensure the reliability of the potential. The ML-PES is then used to compute vibrational states within the MCTDH framework, and assign spectral transitions for the most common isotopologues of these species in the interstellar medium. Our results are compared with previously recorded values, revealing that both cations exhibit a prominent proton-shuttle motion within the infrared spectral range, making them strong candidates for telescopic observation. This study provides a solid computational foundation, based on rigorous, fully quantum treatments, aiming to assist in the identification of these yet unobserved He/Ne hydride cations in astrophysical environments. Full article

The acceleration of the climate crisis and increased demand for water have caused water stress in many agricultural lands worldwide. This issue is of utmost importance as water stress represents one of the most crucial challenges for the agricultural sector and food security, affecting the growth and yield of crops. Developing agricultural strategies to mitigate the adverse effects of water stress and improve crop stress tolerance and crop yield is therefore crucial. This review aimed to analyze the effect of agricultural practices such as elicitation and biostimulation on mitigating the effects of water stress in vegetables. This manuscript provides relevant and recent information about the studied effects on various vegetable species and their responses under water deficit and agricultural and non-agricultural strategies to mitigate water stress, highlighting the use of elicitors and biostimulants. Inclusion criteria were scientific reports and book chapters published from 2000 to 2024, including keywords as follows: water stress + vegetables, water deficit + effects, drought stress management, agricultural strategies for water stress management, eustressors + water stress, elicitors and biostimulants + water stress mitigation. According to the reported literature, it was found that the physiological, biochemical, and molecular responses of vegetables to water stress depended on factors such as the severity and duration of the water deficit, the plant species, and the phenological state of the plants. Traditional agronomic strategies such as tillage, mulching, and intercropping for crop drought management were evaluated. Recently, alternative strategies for mitigating the effects of water stress have gained significant interest, such as the exogenous application of phytohormones and osmoprotectants, nutrient management, and the use of UV-B light, radiation, and acoustic waves, among others, whose eustressive effects (as biostimulants and elicitors) have been demonstrated. Among these eustressors, those of physical origin show great potential for mitigating water stress. To improve the individual potential of eustressors for water stress mitigation, we proposed the combination of practices such as tillage, mulching, application of hormones and osmoprotectants, and physical elicitors and biostimulants such as gamma rays, He-Ne laser, and UV-B. Further exploration is required to establish doses, application conditions, and effects on water stress mitigation and vegetable yield, underscoring the importance and ongoing nature of this research. Full article

Background: Ovarian aging is characterized by the accumulation of free radicals, leading to tissue damage and affecting reproductive health. Intravascular laser irradiation of blood (ILIB, using a low-energy He-Ne laser) is known for its efficacy in treating vascular-related diseases by reducing free radicals and inflammation. However, its impact on ovarian aging remains unexplored. This study aimed to investigate the effects of ILIB on oxidative stress and energy metabolism in aging ovaries. Methods: Genetic analysis was conducted on 75 infertile patients with aging ovaries, divided into ILIB-treated and control (CTRL) groups. Patients underwent two courses of laser treatment, and clinical parameters were evaluated. Cumulus cells were collected for the genetic analysis of oxeiptosis, glycolysis, and the tricarboxylic acid (TCA) cycle. Results: The analysis of gene expression patterns revealed intriguing findings in ILIB-treated patients compared to the untreated group. Notably, ILIB treatment resulted in significant upregulation of oxeiptosis-related genes AIFM1 and NRF2, suggesting a potential protective effect against oxidative stress-induced cell death. Furthermore, ILIB treatment led to a downregulation of glycolysis-associated gene hexokinase 2 (HK2), indicating a shift away from anaerobic metabolism, along with an increase in PDHA levels, indicative of enhanced mitochondrial function. Consistent with these changes, ILIB-treated patients exhibited elevated expression of the key TCA cycle genes citrate synthase (CS), succinate dehydrogenase complex subunit A (SDHA), and fumarate hydratase (FH), signifying improved energy metabolism. Conclusion: The findings from this study underscore the potential of ILIB as a therapeutic strategy for mitigating ovarian aging. By targeting oxidative stress and enhancing energy metabolism, ILIB holds promise for preserving ovarian function and reproductive health in aging individuals. Further research is warranted to elucidate the underlying mechanisms and optimize the application of ILIB in clinical settings, with the ultimate goal of improving fertility outcomes in women experiencing age-related ovarian decline. Full article

Sputtering of silicon in a He magnetron discharge (MS) has been reported as a bottom-up procedure to obtain He-charged silicon films (i.e., He nanobubbles encapsulated in a silicon matrix). The incorporation of heavier noble gases is demonstrated in this work with a synergistic effect, producing increased Ne and Ar incorporations when using He–Ne and He–Ar gas mixtures in the MS process. Microstructural and chemical characterizations are reported using ion beam analysis (IBA) and scanning and transmission electron microscopies (SEM and TEM). In addition to gas incorporation, He promotes the formation of larger nanobubbles. In the case of Ne, high-resolution X-ray photoelectron and absorption spectroscopies (XPS and XAS) are reported, with remarkable dependence of the Ne 1s photoemission and the Ne K-edge absorption on the nanobubble’s size and composition. The gas (He, Ne and Ar)-charged thin films are proposed as “solid” targets for the characterization of spectroscopic properties of noble gases in a confined state without the need for cryogenics or high-pressure anvils devices. Also, their use as targets for nuclear reaction studies is foreseen. Full article

He-Ne lasers play a crucial role in ultra-precision measurement and optical sensing across various fields. For many applications based on He-Ne lasers, a higher output power is required to enhance the accuracy and signal-to-noise ratios of the associated optical measurements. However, conventional methods to increase the output power by reducing the diameter of the He-Ne laser discharge capillary inevitably result in higher diffraction losses and constrain the lasing performance. Here, we propose an approach to enhance laser pumping efficiency and output power through optimizing the ratios of He and Ne gasses. The validity of our proposal has been confirmed by both numerical simulations of He-Ne laser plasma discharge processes and experimental demonstrations, showing that the optimal gas ratio increases with the capillary diameter and total gas pressure. Full article

In this study, we simultaneously measured the group refractive index dispersion and thickness of fused silica using a scanning white light interferometer on a spectral range from 800 to 1050 nm. A delay error correction was performed using a He-Ne laser. The accuracy of the measured group refractive index dispersion of fused silica, when compared to the temperature-dependent Sellmeier equation, is within 4 × 10⁻⁵. Full article

Simmondsia chinensis is a dioecious, long-lived perennial shrub. Its leaves contain several antioxidant flavonoids that have numerous pharmacological effects. Various strategies have been explored to propagate jojoba with enhanced pharmacological values. This research evaluates the bio-stimulatory impacts of He–Ne laser seed irradiation on seed germination, plantlet growth, and alteration of the composition and bioactivities of phytochemicals in jojoba plants. Jojoba seeds were irradiated for 5, 10, and 15 min before in vitro germination. Germination, growth, and multiplication parameters were recorded during germination, multiple-shoot induction, and rooting stages. The wound healing and antimicrobial activities of methanolic extracts from plant lines obtained from the non-irradiated (control) and 10 min irradiated seeds were compared by excision wound model in Wistar male rats and zone of inhibition assay. Our study revealed that laser irradiation increased seed germination, with the highest percentage observed in seeds irradiated for 10 min. Plant lines from the 10 min irradiated seeds produced more explants with higher explant heights and numbers of leaves, more roots, and higher photosynthetic pigment contents than those of control and other laser testings. By comparing plant extracts from the control and 10 min treatments, we observed that extracts from the 10 min treatment exhibited higher percentages of wound contraction and shorter epithelialization periods. In addition, these extracts also resulted in higher levels of angiogenesis elements (VEGF, TGF-β1, and HIF-1α) and reduced the inflammation regulators (IL-1β, IL-6, TNF-α, and NFκB) in the experimental rats. In concordance, extracts from the 10 min treatment also explained raised antibacterial activities towards Staphylococcus aureus and Escherichia coli. Our findings show that pre-sowing seed treatment with a He–Ne laser (632.8 nm) could be a good technique for stimulating S. chinensis plant growth and increasing the impact compound levels and biological activities. Full article

In this study, a polyvinyl alcohol–sodium alginate blend, PVA:SA 3:1 (w:w), was doped with different contents of TiO₂ nanoparticles (NPs) prepared by aloe vera leaf extract to form the investigated nanocomposites. The nonlinear parameters of third-order susceptibility (χ⁽³⁾) and refractive index (n₂) were detected by using UV-Vis spectroscopy and Z-scan techniques. Some different optical parameters were also determined, including the refractive index (n), optical dielectric parameters, volume and surface energy loss functions, and some others. The best solar skin protection factor (SSPF) was investigated by 5 wt.% of TiO₂ NPs doped in PVA:SA 3:1, which was about 84.6% compared to the corresponding value of the host blend (41%). The studied nanocomposites were examined for their utility in the optical limiting of CUT-OFF laser filters utilizing a continuous He-Ne laser working at 632.2 nm. As a result, our finding demonstrated that TiO₂ NPs doped in the host blend of PVA:SA positively influences a laser light blocking for the investigated laser source. Using the estimated gap energies values, different models were used to deduce theoretical values of the linear refractive index (n). The presence of Ti peaks in the EDX spectrum confirmed the doping of TiO₂ NPs in the nanocomposites. SEM showed that the TiO₂ NPs are homogeneously dispersed through the host blend with some agglomerates. XRD spectra showed that the values of the lattice strain ε_str. detected at 2ϴ = 19.78° are 0.058, 0.055, and 0.060, corresponding to 1, 3, and 5 wt.% of TiO₂ NPs doped in the PVA:SA blend. Full article

Silybum marianum is a medicinal plant that produces silybins A and B, which exhibit liver-protective activities. The He–Ne laser pre-sowing seed treatment has been used as a physical biostimulator in numerous plants to promote seed germination, plant growth, and secondary metabolite production. Thus, in this study, a He–Ne laser at 632.8 nm was used to irradiate S. marianum seeds with the aim of promoting plant growth as well as enhancing the production of silybin (A + B). The seeds were irradiated with a He–Ne laser for 2, 4, 6, 8, and 10 min. The growth attributes of the plants, as well as the silybin (A + B) content and bioactivities of fruit extracts from various treatment groups, were compared. The results indicated that all laser seed treatments resulted in a subsequent increase in plant growth, with the highest yield observed in the 10 min laser treatment. An increase in fruit silybin (A + B) content and in chalcone synthase gene expressions were observed in plants from the 6-, 8-, and 10-min laser-irradiated seeds. The highest silybin (A + B) contents were observed in plants from the 6-min-irradiated seeds. Furthermore, the corresponding fruit extract also exhibited elevated cell growth inhibition in the Dictyostelium discoideum cell model. Full article

Since the turn of the millennium, the development and commercial availability of optical frequency combs has led to a steadily increase of worldwide installed frequency combs and a growing interest in using them for industrial-related metrology applications. Especially, GPS-referenced frequency combs often serve as a “self-calibrating” length standard for laser wavelength calibration in many national metrology institutes with uncertainties better than u = 1 × 10⁻¹¹. In this contribution, the application of a He-Ne laser source permanently disciplined to a GPS-referenced frequency comb for the interferometric measurements in a nanopositioning machine with a measuring volume of 200 mm × 200 mm × 25 mm (NPMM-200) is discussed. For this purpose, the frequency stability of the GPS-referenced comb is characterized by heterodyning with a diode laser referenced to an ultrastable cavity. Based on this comparison, an uncertainty of u = 9.2 × 10⁻¹² (τ = 8 s, k = 2) for the GPS-referenced comb has been obtained. By stabilizing a tunable He-Ne source to a single comb line, the long-term frequency stability of the comb is transferred onto our gas lasers increasing their long-term stability by three orders of magnitude. Second, short-term fluctuations-related length measurement errors were reduced to a value that falls below the nominal resolving capabilities of our interferometers (ΔL/L = 2.9 × 10⁻¹¹). Both measures make the influence of frequency distortions on the interferometric length measurement within the NPMM-200 negligible. Furthermore, this approach establishes a permanent link of interferometric length measurements to an atomic clock. Full article

On a Wendelstein 7-X (W7-X), an alkali metal beam (AMB) diagnostic system was installed in order to measure the plasma edge electron density profiles and turbulence transport. A sodium beam was injected in the plasma, and the light emission was observed by an optical system. During the last operation phase, OP1.2b campaign trial spectral measurements were performed with a dedicated optical branch. The results showed the emergence of potential CX lines in the light spectra during sodium injection. The lines were identified as Carbon III, which were the dominant lines observed by other diagnostics at the edge plasma. Based on these results, an additional dedicated optical system was developed and installed in 2021 for the upcoming operational phase, OP2. The optics were designed for multiple purposes: spectral measurements for the AMB system and for a He/Ne gas jet. The system was designed to allow implementation of further diagnostics on this port later (e.g., coherence imaging system). The details of the implementation of the design requirements and the main challenges of the manufacturing process and installation are discussed in this paper. Full article

New organic stilbazolium family of 4-[2-(3 methoxy-phenyl)-vinyl]-1-methyl-pyridinium⁺ iodide⁻ (MMPI) was successfully synthesized using the condensation reaction method. The recrystallization process was carried out to improve the purity of the synthesized material, and MMPI and grown into a single crystal by the solvent evaporation method. The solubility of the (MMPI) material was taken at different temperatures with a mixture of solvent Methanol: Acetonitrile (1:1). The grown MMPI crystal structure and cell parameters were solved via single crystal X-ray diffraction analysis. The structural formation of the title material was also confirmed by Nuclear Magnetic Resonance spectroscopic (NMR) studies. The experimental vibrational bands in the synthesized material have been assigned by Fourier Transform Infrared (FT-IR) spectrum analysis. From the optical analysis, the grown crystal’s lower cut-off wavelength, transmittance range, and optical band gap were calculated. Chemical etching analysis was carried out on the grown crystal surface (MMPI) to study the surface property of the grown MMPI crystal. Along with etching, atomic force microscope (AFM) and scanning electron microscope (SEM) were also used to analyses the grown MMPI crystal surface. Hirshfeld surface analysis was used to analyses the intermolecular interactions. HOMO and LUMO energies were calculated theoretically using the Gaussian View 6 programmer. The chemical activity was evaluated via the molecular electrostatic potential using the density functional theory (DFT) method. The third-order nonlinear optical parameters of the title crystal were evaluated at He-Ne laser (632.8 nm) source with the single beam Z-scan technique. In addition, it shows significant reverse saturable absorption and self-defocusing. Full article

In this work, we study the light-induced changes of the rotational speed of a thin photomobile film using a single-axis acoustic levitator operating at 40 kHz. In our experiments, a 50 μm thick photomobile polymer film (PMP) is placed in one of the nodes of a stationary acoustic field. Under the action of the field, the film remains suspended in air. By externally perturbing this stable equilibrium condition, the film begins to rotate with its natural frequency. The rotations are detected in real time by monitoring the light of a low power He–Ne laser impinging on and reflected by the film itself. During the rotational motion, an external laser source is used to illuminate the PMP film; as a consequence, the film bends and the rotational speed changes by about 20 Hz. This kind of contactless long-distance interaction is an ideal platform for the development and study of many electro-optics devices in microgravity and low-friction conditions. In particular, we believe that this technology could find applications in research fields such as 3D dynamic displays and aerospace applications. Full article