Wavelength-dependent Manner Research Articles

Quantifying the Photosynthetic Quantum Yield of Ultraviolet-A1 Radiation.

Although it powers photosynthesis, ultraviolet-A1 radiation (UV-A1) is usually not defined as photosynthetically active radiation (PAR). However, the quantum yield (QY) with which UV-A1 drives net photosynthesis rate (A) is unknown, as are the kinetics of A and chlorophyll fluorescence under constant UV-A1 exposure. We measured A in leaves of six genotypes at four spectra peaking at 365, 385, 410 and 450 nm, at intensities spanning 0-300 μmol m s-1. All treatments powered near-linear increases in A in a wavelength-dependent manner. QY at 365 and 385 nm was linked to the apparent concentration of flavonoids, implicating the pigment in reductions of photosynthetic efficiency under UV-A1; in several genotypes, A under 365 and 385 nm was negative regardless of illumination intensity, suggesting very small contributions of UV-A1 radiation to CO2 fixation. Exposure to treatment spectra for 30 min caused slow increases in nonphotochemical quenching, transient reductions in A and dark-adapted maximum quantum yield of photosystem II, that depended on wavelength and intensity, but were generally stronger the lower the peak wavelength was. We conclude that UV-A1 generally powers A, but its definition as PAR requires additional evidence of its capacity to significantly increase whole-canopy carbon uptake in nature.

Bond Selective Photochemistry at Metal Nanoparticle Surfaces: CO Desorption from Pt and Pd.

The use of visible photon fluxes to influence catalytic reactions on metal nanoparticle surfaces has attracted attention based on observations of reaction mechanisms and selectivity not observed under equilibrium heating. These observations suggest that photon fluxes can selectively impact the rates of certain elementary steps, creating nonequilibrium energy distributions among various reaction pathways. However, quantitative studies validating these hypotheses on metal nanoparticle surfaces are lacking. We examine the influence of continuous wave visible photon fluxes on the CO desorption rates from 1 to 2 nm diameter Pt and Pd nanoparticle surfaces supported on γ-Al2O3. Temperature-programmed desorption measurements quantified via diffuse reflectance infrared Fourier transform spectroscopy demonstrate that visible photon fluxes significantly enhanced the rate of CO desorption from Pt nanoparticles in a wavelength-dependent manner. 440 nm photons most efficiently promoted CO desorption from Pt nanoparticle surfaces, aligning with the excitation energy for the interfacial electronic transition within the Pt-CO bond. Conversely, visible photon fluxes had no measurable influence on CO desorption rates from Pd nanoparticle surfaces after accounting for photon-induced heating. Density functional theory calculations demonstrate that the Pt-CO bond exhibits a narrower LUMO resonance, stronger coupling between the photoexcitation and forces induced on the metal-C bond, and vibrational energy dissipation that more effectively couples to desorption as compared to Pd-CO. These results demonstrate the specificity photons provide in facilitating chemical reactions on metal nanoparticle surfaces and substantiate the idea that photon fluxes can steer processes and outcomes of catalytic reactions in ways not achievable by equilibrium heating.

Spectroscopic diagnostics of lead stratification in hot subdwarf atmospheres

ABSTRACT Heavy metal subdwarfs are a class of hot subdwarfs with very high abundances of heavy elements, typically around 10 000 times solar. They include stars, which are strongly enhanced in either lead or zirconium, as well as other elements. Vertical stratification of the enhanced elements, where the element is concentrated in a thin layer of the atmosphere, has been proposed as a mechanism to explain the apparent high abundances. This paper explores the effects of the vertical stratification of lead on the theoretical spectra of hot subdwarfs. The concentration of lead in different regions of the model atmosphere is found to affect individual lines in a broadly wavelength-dependent manner, with the potential for lines to display modified profiles depending on the location of lead enhancement in the atmosphere. This wavelength dependence highlights the importance of observations in both the optical and the UV for determining whether stratification is present in real stars.

Chromatic aberration correction employing reinforcement learning.

In fluorescence microscopy a multitude of labels are used that bind to different structures of biological samples. These often require excitation at different wavelengths and lead to different emission wavelengths. The presence of different wavelengths can induce chromatic aberrations, both in the optical system and induced by the sample. These lead to a detuning of the optical system, as the focal positions shift in a wavelength dependent manner and finally to a decrease in the spatial resolution. We present the correction of chromatic aberrations by using an electrical tunable achromatic lens driven by reinforcement learning. The tunable achromatic lens consists of two lens chambers filled with different optical oils and sealed with deformable glass membranes. By deforming the membranes of both chambers in a targeted manner, the chromatic aberrations present in the system can be manipulated to tackle both systematic and sample induced aberrations. We demonstrate chromatic aberration correction of up to 2200 mm and shift of the focal spot positions of 4000 mm. For control of this non-linear system with four input voltages, several reinforcement learning agents are trained and compared. The experimental results show that the trained agent can correct system and sample induced aberration and thereby improve the imaging quality, this is demonstrated using biomedical samples. In this case human thyroid was used for demonstration.

Photoinhibition of comammox reaction in Nitrospira inopinata in a dose- and wavelength-dependent manner.

Apparent contribution of complete ammonia-oxidizing organisms (comammox) to the global nitrogen cycle highlights the necessity for understanding niche differentiation of comammox bacteria among other ammonia oxidizers. While the high affinity for ammonia of the comammox species Nitrospira inopinata suggests their niche partitioning is expected to be centered in oligotrophic environments, their absence in nutrient-depleted environments (such as the oceans) suggests that other (abiotic) factors might control their distribution and spatial localization within microbial communities. Many ammonia- and nitrite-oxidizing organisms are sensitive to light; however, the photosensitivity of comammox has not been explored. Since comammox bacteria encode enzymatic machinery homologous to canonical ammonia-and nitrite-oxidizers, we hypothesized that comammox N. inopinata, the only available pure culture of this group of microorganisms, may be inhibited by illumination in a similar manner. We evaluated the impact of light intensity, wavelength, and duration on the degree of photoinhibition for cultures of the comammox species N. inopinata and the soil ammonia-oxidizing archaea Nitrososphaera viennensis. Both species were highly sensitive to light. Interestingly, mimicking diurnal light exposure caused an uncoupling of ammonia and nitrite oxidation in N. inopinata, indicating nitrite oxidation might be more sensitive to light exposure than ammonia oxidation. It is likely that light influences comammox spatial distribution in natural environments such as surface fresh waters according to diurnal cycles, light attenuation coefficients, and the light penetration depths. Our findings therefore provide ecophysiological insights for further studies on comammox both in field and laboratory settings.

Wavelength dependent equilibrium mode distribution and steady-state distribution in double-clad W-type microstructured polymer optical fibers

This paper investigates wavelength dependence of equilibrium mode distribution and steady-state distribution in W-type (double-clad) microstructured polymer optical fibers (mPOFs) with a solid core for parametrically varied refractive index and width of the intermediate layer (IL) (inner cladding) by solving the time-independent power flow equation (TI PFE). In the case of wider IL, independent of wavelength, the lengths for establishing the equilibrium mode distribution and steady-state distribution are larger. We have demonstrated that the wavelength has no effect on these lengths for IL’s width that is larger. These lengths drop in a wavelength-dependent manner as the IL's width decreases. Equilibrium mode distribution and steady-state distribution occur at shorter optical fiber lengths as the depth of the IL diminishes, which is due to the similarly declining number of leaky modes. The smaller the depth of the IL, the shorter the fiber length is required for completion of the coupling process. These programmable characteristics allow double-clad W-type mPOFs to be easier customized for a particular use in optical fiber sensors and communications at various wavelengths.

Major target for UV-induced complete loss of HIV-1 infectivity: A model study of single-stranded RNA enveloped viruses

Deep ultraviolet light (UV) is useful for the disinfection of microorganisms, including bacteria and viruses. Although genome damage by UV has been widely accepted, the adverse effects of UV on the activity and/or function of viral proteins including the envelope components are poorly documented. Worthy of note, the observed unfavorable UV-effects for viruses are only insufficiently analyzed in association with the reduction in viral infectivity. In this study, we aimed to clarify which component of virions affected by UV significantly correlates with the loss of viral infectivity using HIV-1 as a model for single-stranded RNA enveloped viruses. Using our UV irradiation apparatus at three wavelengths (265, 280, and 300 nm), we first quantitatively determined the UV power density and irradiation period of each wavelength required for a reduction in infectivity. A heat-treated sample as a control drastically reduced the virion-associated reverse transcriptase (RT) activity and Gag-p24 level. The UV-irradiated samples at the three wavelengths, completely lacking viral infectivity, showed p24 levels similar to those without irradiation. While the virion-associated RT activity was gradually decreased in a wavelength and power density dependent manner, this reduction did not explain the loss of viral infectivity by UV. Remarkably, virological assays revealed that the entry efficiency of the UV-irradiated virus samples at the three wavelengths is comparable to those without irradiation. Importantly, this result shows that, even the virions exposed to UV of various wavelengths at the lethal level, still maintain the function of their envelope composed of a host lipid bilayer and viral proteins. In sharp contrast, UV-induced genome damage shown by semiquantitative RT-PCR correlated well with the reduction in viral infectivity, indicating that it is a major determinant for virus inactivation by UV. The degree of damage was found to be distinct among the regions analyzed. This was probably due to the different nucleotide sequences in those genomic regions amplified by PCR. Our data clearly demonstrate a principal mechanism for viral inactivation by UV and provide information contributing to the improvement of UV-based disinfection technology for microorganisms.

Degradation of Lignin by Infrared Free Electron Laser.

Lignin monomers have attracted attention as functional materials for various industrial uses. However, it is challenging to obtain these monomers by degrading polymerized lignin due to the rigid ether linkage between the aromatic rings. Here, we propose a novel approach based on molecular vibrational excitation using infrared free electron laser (IR-FEL) for the degradation of lignin. The IR-FEL is an accelerator-based pico-second pulse laser, and commercially available powdered lignin was irradiated by the IR-FEL under atmospheric conditions. Synchrotron-radiation infrared microspectroscopy analysis showed that the absorption intensities at 1050 cm−1, 1140 cm−1, and 3400 cm−1 were largely decreased alongside decolorization. Electrospray ionization mass chromatography analysis showed that coumaryl alcohol was more abundant and a mass peak corresponding to hydrated coniferyl alcohol was detected after irradiation at 2.9 μm (νO-H) compared to the original lignin. Interestingly, a mass peak corresponding to vanillic acid appeared after irradiation at 7.1 μm (νC=C and νC-C), which was supported by our two-dimensional nuclear magnetic resonance spectroscopy analysis. Therefore, it seems that partial depolymerization of lignin can be induced by IR-FEL irradiation in a wavelength-dependent manner.

Photobiomodulation Modulates Interleukin-10 and Interferon Gamma Production by Mononuclear Cells from Healthy Donors and Persons with Multiple Sclerosis.

Background: Photobiomodulation (PBM) therapy was previously shown to reduce the clinical severity of disease and modulated pro- and anti-inflammatory cytokines in an animal model of multiple sclerosis (MS). Objective: Previous observations were extended to determine the effect of PBM therapy on peripheral blood mononuclear cells and CD4+ T cells isolated from persons with MS (PwMS) and healthy donors. Methods: Using an in vitro cell culture system, isolated cells were activated and treated with red or near-infrared light wavelengths to determine the effect of PBM on the production of interferon gamma and interleukin-10 (IL-10). Results: PBM modulated cytokine production in MS subjects and healthy donors in a dose- and wavelength-dependent manner, with MS subjects and healthy donors responding differently to administered light. In addition, disease severity affected the response of immune cells, for instance, 670 nm increased IL-10 production associated with increased disease severity. Conclusions: The data show that PBM therapy has the potential to modulate pro- and anti-inflammatory cytokines in PwMS over the course of disease. Further experiments applying PBM treatment directly on patients should be carried out with extreme caution to avoid severe imbalance in the immune response.

The potential contribution of the WRKY53 transcription factor, gamma-aminobutyric acid (GABA) transaminase, and histone deacetylase in regulating growth, organogenesis, photosynthesis, and transcriptional responses of tomato to different light-emitting diodes (LEDs).

Impressive progress in developing light-emitting diodes (LEDs) offers a new dimension for meeting agricultural and biological expectations. The present study addresses how tomato (Solanum lycopersicum) seedlings respond to the different spectral qualities of LEDs (white, red, blue, and blue + red). The light treatments in a wavelength-dependent manner contributed to the variations in biomass accumulation, morphology, and organogenesis pattern. Light quality epigenetically contributed to the transcriptional regulation of the histone deacetylase (HDA3) gene. The expression of WRKY53 transcription factor and gamma-aminobutyric acid transaminase (GABA-TP1) genes displayed a similar upward trend in response to the blue wavelength. On the contrary, the sole red light downregulated the WRKY53 and GABA-TP1 genes. The blue irradiation was associated with the upregulation in the glycolate oxidase (GLO2) and ribulose-1,5-bisphosphate carboxylase‑oxygenase large subunit (rbcL) genes, while the red wavelength down-regulated the GLO2 and rbcL genes. Moreover, rbcL statistically correlated with GLO2, referring to the balanced regulation of photorespiration and the Calvin cycle. The blue wavelengths were more capable of improving the concentrations of photosynthetic pigments and proline. The seedlings grown under the white LEDs displayed the maximum activity of the catalase enzyme. The cultivation of tomato seedlings under the blue lights enhanced the activities of the superoxide dismutase and ascorbate peroxidase enzymes. The light treatments were associated with the variation in the nutritional status of K+ and Ca2+ in both leaves and roots. The presented findings and inferences support the potential contribution of WRKY53, HDA3, and GABA signaling in modulating plant responses to light quality.

Wavelength-Dependent Bifunctional Plasmonic Photocatalysis in Au/Chalcopyrite Hybrid Nanostructures.

Excited, or "hot" charge carrier generation and transfer driven by the decay of localized surface plasmon resonances (LSPRs) are key steps in plasmonic photocatalysis. Hybrid structures that contain both metal and semiconductor building blocks facilitate the extraction of reactive charge carriers and their utilization for photoelectrocatalysis. Additional functionality arises from hybrid structures that combine noble metal nanostructures with semiconductor components, such as chalcopyrite (CuFeS2) nanocrystals (NCs), which by themselves support quasistatic resonances. In this work, we use a hybrid membrane to integrate Au nanorods (NRs) with a longitudinal LSPR at 745 nm and CuFeS2 NCs with a resonance peak at 490 nm into water-stable nanocomposites for robust and bifunctional photocatalysis of oxygen and hydrogen evolution reactions in a wavelength-dependent manner. Excitation of NRs or NCs in the nanocomposite correlates with increased hydrogen or oxygen evolution, respectively, consistent with a light-driven electron transfer between the metal and semiconductor building blocks, the direction of which depends on the wavelength. The bifunctional photoreactivity of the nanocomposite is enhanced by Cu(I)/Cu(II)-assisted catalysis on the surface of the NCs.

Short-wavelength light induces broiler’s behavioral and physiological syndrome through a misaligned eating rhythm

Previous work shows that long-wavelength light has a robust circadian rhythmic pattern in the expression of clock genes of chickens, whereas short-wavelength light leads to an arrhythmic oscillation of some clock genes (e.g., cClock, cCry1, cCry2, cPer2, and cPer3). However, knowledge about the consequences of LED lights on the physiological and behavioral phenotype was still not clear. This experiment hypothesizes that short-wavelength light disturbs chickens’ eating rhythm and leads to the wrong time to eat, resulting in metabolic syndrome. “Meihuang” broilers were housed in monochromatic LED blue light, green light, yellow light, red light, or white light with a very low dose (15 lx). Multiply physiological parameters were measured and the 24-h eating behavior was determined. The effects of LED light on physiological status and behavioral phenotype showed a wavelength-dependent manner. Short-wavelength light significantly decreased the level of total triglycerides and total cholesterol but increased triiodothyronine concentration. Inversely, long-wavelength light increased the triglycerides and total cholesterol and reduced the level of triiodothyronine. Further, it was found that short-wavelength light significantly boosted body weight compared with long-wavelength light, despite equivalent levels of food intake. Short-wavelength light-induced 23.4% and 14.1% of food consumption during subjective nights, but long-wavelength light did not. These results imply that when chickens eat matters, not just what they eat. Thus, low as 15 lx of blue light exposure during the typical dark period is sufficient to lead an individual to eat at the “wrong” time, causing metabolic dysfunction. Blue light should be cautiously considered to be used in the poultry breeding process. Keywords: short-wavelength light, broiler, behavior, physiology, environmental control, circadian rhythm, intermittent eating DOI: 10.25165/j.ijabe.20221503.6456 Citation: Yang Y F, Liu Q, Wang S Y, Zeng L, Pan C H, Jado A, et al. Short-wavelength light induces broiler’s behavioral and physiological syndrome through a misaligned eating rhythm. Int J Agric & Biol Eng, 2022; 15(3): 47–54.

Ultraviolet Radiation and Melanomagenesis: From Mechanism to Immunotherapy.

Melanoma is the deadliest form of skin cancer, and nearly 90% of melanomas are believed to be caused by ultraviolet radiation (UVR), mainly from sunlight. UVR induces DNA damage, forming products such as cyclobutane pyrimidine dimers (CPD) and 6-4-pyrimidone photoproducts (6-4PP) in a wavelength-dependent manner and causes oxidative DNA damage. These DNA lesions lead to DNA mutations and contribute to the formation of melanoma. In this review, we discuss the protective role of melanocytes against UV-induced DNA damage and how genetic variations, including those in p53 and melanocortin-1 receptor (MC1R), or epigenetic histone modifications in melanocytes result in a tendency toward melanoma. We also provide a summary of prevention and treatment strategies against melanoma, including the most recent immunotherapies. Collectively, this work contributes to the understanding of the molecular pathogenesis of UV-induced melanoma.

Effects of photobiomodulation on annulus fibrosus cells derived from degenerative disc disease patients exposed to microvascular endothelial cells conditioned medium

Intervertebral disc (IVD) degeneration with chronic low back pain is associated with neo-vascularisation into the deeper IVD regions. During this process, endothelial cells (ECs), which are primarily responsible for angiogenesis, interact with the adjacent annulus fibrosus (AF) cells, which are the first line of defence against the invasion of vascular structures into deeper IVD regions. However, the accumulation of inflammatory and catabolic enzymes that results from this interaction promotes matrix degradation and an inflammatory response. Thus, regulating the production of these mediators and catabolic enzymes could ameliorate IVD degeneration. Photobiomodulation (PBM) therapy is a non-invasive stimulation known to have biologically beneficial effects on wound healing, tissue repair, and inflammation. Here, we examined the effects of PBM, administered at various wavelengths (645, 525, and 465 nm) and doses (16, 32, and 64 J/cm2), on EC-stimulated human AF cells. Our results show that PBM selectively inhibited the EC-mediated production of inflammatory mediators, catabolic enzymes, and neurotrophins by human AF cells in a dose- and wavelength-dependent manner. These results suggest that PBM could be a superior and advanced treatment strategy for IVD degeneration.

Activation of an Endogenous Opsin 3 Light Receptor Mediates Photo-Relaxation of Pre-Contracting Late Gestation Human Uterine Smooth Muscle Ex Vivo.

Spontaneous preterm birth (sPTB) remains a worldwide healthcare challenge. Preterm labor (PTL) is thought to be the largest reversible cause of sPTB, but current tocolytic therapies are ineffective and associated with systemic side effects from chronic use. Therefore, identifying novel mechanisms that promote human uterine smooth muscle (hUSM) relaxation is essential to improving clinical management of PTL. Here, we aimed to determine if an extraocular opsin receptor (OPN 3,4,5) system is expressed in pregnant hUSM and to characterize how photo-mediated relaxation of pre-contracting hUSM may be facilitated by external application of light. Translational studies were performed with hUSM from healthy late gestation patients (n = 8) and non-pregnant, similarly aged patients undergoing hysterectomy (n = 4). First, RT-PCR screened for mRNA coding for components of the classical extraocular light receptors (OPN 3,4,5). We found a restricted repertoire of opsin receptors (OPN3) expressed in pregnant hUSM tissue. Immunohistochemistry was performed to confirm protein expression. Pre-contracting late gestation hUSM strips were studied in functional organ bath studies to determine if photo-mediated relaxation is intensity or wavelength dependent. Functional organ bath studies revealed acute photo-mediated relaxation occurring in an intensity- and wavelength-dependent manner. Finally, coimmunoprecipitation of OPN3 with Gs following light activation suggests that a component of photo-relaxation occurs via G protein-coupled receptor machinery. This is the first report of light-mediated relaxation of pre-contracted human myometrium. Activation of endogenous light receptors on human myometrium may become a novel, non-invasive tocolytic strategy.

Wavelength-specific artificial light disrupts molecular clock in avian species: A power-calibrated statistical approach

Nighttime lighting is an increasingly important anthropogenic environmental stress on plants and animals. Exposure to unnatural lighting environments may disrupt the circadian rhythm of organisms. However, the sample size of relevant studies, e.g. disruption of the molecular circadian clock by light pollution, was small (<10), which led to low statistical power and difficulties in replicating prior results. Here, we developed a power-calibrated statistical approach to overcome these weaknesses. The results showed that the effect size of 2.48 in clock genes expression induced by artificial light would ensure the reproducibility of the results as high as 80%. Long-wavelength light (560–660 nm) entrained expressions of the positive core clock genes (e.g. cClock) and negative core clock genes (e.g. cCry1, cPer2) in robust circadian rhythmicity, whereas those clock genes were arrhythmic in short-wavelength light (380–480 nm). Further, we found artificial light could entrain the transcriptional-translational feedback loop of the molecular clock in a wavelength-dependent manner. The expression of the positive core clock genes (cBmal1, cBmal2 and cClock), cAanat gene and melatonin were the highest in short-wavelength light and lowest in long-wavelength light. For the negative regulators of the molecular clock (cCry1, cCry2, cPer2 and cPer3), the expression of which was the highest in long-wavelength light and lowest in short-wavelength light. Our statistical approach opens new opportunities to understand and strengthen conclusions, comparing with the studies with small sample sizes. We also provide comprehensive insight into the effect of wavelength-specific artificial light on the circadian rhythm of the molecular clock in avian species. Especially, the global lighting is shifting from “yellow” sodium lamps, which is more like the long-wavelength light, toward short-wavelength light (blue light)-enriched “white” light-emitting diodes (LEDs).

Far-red light enhances photochemical efficiency in a wavelength-dependent manner.

Linear electron transport depends on balanced excitation of photosystem I and II. Far-red light preferentially excites photosystem I (PSI) and can enhance the photosynthetic efficiency when combined with light that over-excites photosystem II (PSII). The efficiency of different wavelengths of far-red light exciting PSI was quantified by measuring the change in quantum yield of PSII (ΦPSII ) of lettuce (Lactuca sativa) under red/blue light with narrowband far-red light added (from 678 to 752 nm, obtained using laser diodes). The ΦPSII of lettuce increased with increasing wavelengths of added light from 678 to 703 nm, indicating longer wavelengths within this region are increasingly used more efficiently by PSI than by PSII. Adding 721 nm light resulted in similar ΦPSII as adding 703 nm light, but ΦPSII tended to decrease as wavelength increased from 721 to 731 nm, likely due to decreasing absorptance and low photon energy. Adding 752 nm light did not affect ΦPSII . Leaf chlorophyll fluorescence light response measurements showed lettuce had higher ΦPSII under halogen light (rich in far-red) than under red/blue light (which over-excites PSII). Far-red light is more photosynthetically active than commonly believed, because of its synergistic interaction with light of shorter wavelengths.

Photobiomodulation of extracellular matrix enzymes in human nucleus pulposus cells as a potential treatment for intervertebral disk degeneration

Intervertebral disc (IVD) degeneration is associated with imbalances between catabolic and anabolic responses, regulated by extracellular matrix (ECM)-modifying enzymes such as matrix metalloproteinases (MMPs) and their endogenous tissue inhibitors of metalloproteinases (TIMPs). Potential contributing factors, such as interleukin (IL)-1β and tumor necrosis factor (TNF)-α, derived from infiltrated, activated macrophages within IVD tissues, can trigger abnormal production of ECM-modifying enzymes and progression of IVD degeneration. Novel therapies for regulating ECM-modifying enzymes can prevent or ameliorate IVD degeneration. Photobiomodulation (PBM), known to regulate wound repair, exhibits regenerative potential by modulating biological molecules. This study examined the effects of PBM, administered at various wavelengths (630, 525, and 465 nm) and energy densities (16, 32, and 64 J/cm2), on the production of ECM-modifying enzymes in replicated degenerative IVD. Our results showed that PBM selectively inhibited the production of ECM-modifying enzymes in a dose- and wavelength-dependent manner, suggesting that it could be a novel tool for treating symptomatic IVD degeneration.

Wavelength-dependence of vasodilation and NO release from S-nitrosothiols and dinitrosyl iron complexes by far red/near infrared light

Far red/near infrared (R/NIR) energy is a novel therapy, but its mechanism of action is poorly characterized. Cytochrome c oxidase (Cco) of the mitochondrial electron transport chain is considered the primary photoacceptor for R/NIR to photolyze a putative heme nitrosyl in Cco to liberate free nitric oxide (NO). We previously observed R/NIR light directly liberates NO from nitrosylated hemoglobin and myoglobin, and recently suggested S-nitrosothiols (RSNO) and dinitrosyl iron complexes (DNIC) may be primary sources of R/NIR-mediated NO. Here we indicate R/NIR light exposure induces wavelength dependent dilation of murine facial artery, with longer wavelengths (740, and 830 nm) exhibiting reduced potency when compared to 670 nm. R/NIR also stimulated NO release from pure solutions of low molecular weight RSNO (GSNO and SNAP) and glutathione dinitrosyl iron complex (GSH-DNIC) in a power- and wavelength-dependent manner, with the greatest effect at 670 nm. NO release from SNAP using 670 was nearly ten-fold more than GSNO or GSH-DNIC, with no substantial difference in NO production at 740 nm and 830 nm. Thermal effects of irradiation on vasodilation or NO release from S-nitrosothiols and DNIC was minimal. Our results suggest 670 nm is the optimal wavelength for R/NIR treatment of certain vascular-related diseases.

Layered semi-convection and tides in giant planet interiors

Layered semi-convection is a possible candidate to explain Saturn's luminosity excess and the abnormally large radius of some hot Jupiters. In giant planet interiors, it could lead to the creation of density staircases, which are convective layers separated by thin stably stratified interfaces. We study the propagation of internal waves in a region of layered semi-convection, with the aim to predict energy transport by internal waves incident upon a density staircase. The goal is then to understand the resulting tidal dissipation when these waves are excited by other bodies such as moons in giant planets systems. We use a local Cartesian analytical model, taking into account the complete Coriolis acceleration at any latitude, thus generalizing previous works. We find transmission of incident internal waves to be strongly affected by the presence of a density staircase, even if these waves are initially pure inertial waves (which are restored by the Coriolis acceleration). In particular, low-frequency waves of all wavelengths are perfectly transmitted near the critical latitude. Otherwise, short-wavelength waves are only efficiently transmitted if they are resonant with a free mode (interfacial gravity wave or short-wavelength inertial mode) of the staircase. In all other cases, waves are primarily reflected unless their wavelengths are longer than the vertical extent of the entire staircase (not just a single step). We expect incident internal waves to be strongly affected by the presence of a density staircase in a frequency-, latitude- and wavelength-dependent manner. First, this could lead to new criteria to probe the interior of giant planets by seismology; and second, this may have important consequences for tidal dissipation and our understanding of the evolution of giant planet systems.