Light Of Wavelength Research Articles

A theoretical study on the photochemical generation of phenylborylene from phenyldiazidoborane.

Organic borylenes are a kind of highly reactive species, which play important roles in a lot of reactions as vigorous intermediates. In this work, we investigated the photochemical generation mechanisms of phenylborylene (PhB) together with the side product N-phenylnitrenoiminoborane (PhNBN) from phenyldiazidoborane (PhBN6) by extrusion of dinitrogen in the two lowest electronic singlet states (S0 and S1) based on the complete active space self-consistent field (CASSCF) and its second-order perturbation (CASPT2) methods combined with time-dependent density functional theory (TD-DFT) calculations. Our results show that the reaction PhBN6 → PhB + 3N2 involves stepwise N2 extrusion three times and the azido region rearrangement. Moreover, we found that the studied photo-induced processes are kinetically feasible because the highest energy barrier is only 0.36 eV and excitation with light of wavelength 254 nm can provide enough excess energy to overcome these energy barriers. Importantly, we revealed that several conical intersections between S1 and S0 states participate and facilitate the studied photochemical processes. Our results not only clarify the experimental observations, (H. F. Bettinger, J. Am. Chem. Soc. 2006, 128, 2534), but also provide valuable insights into borylene chemistry.

Construction of composite films using carbon nanodots for blocking ultraviolet light from the Sun.

Carbon nanodots (CNDs) which demonstrate concentration-dependent emission and have a photoluminescence quantum yield of 45% were designed. Transparent CND-containing composite films (CND-films), obtained by combining the CNDs with polyvinyl alcohol in different proportions, were shown to block the UV component of sunlight. Whereas the pure PVA film could not block UV light, the ability of CND-films to block UV light could be adjusted by altering the proportion of CNDs in the film. The larger the proportion of CNDs, the greater the extent of UV blocking. CND-film containing 32 wt% CNDs completely blocked UV light (≤400 nm) from sunlight, without affecting the transmission of visible light (>800 nm). The ability of the CND-films to block the UV component of sunlight was investigated using a commercially available UV-induced color change card, which confirmed that the capacity of the CND-films to block UV light could be adjusted by altering the proportion of CNDs in the film. This study shows that CNDs with concentration-dependent long wavelength emission characteristics can be used as optical barrier units for the preparation of materials to block high-energy short wavelength light.

A facile and light-controllable drug combination for enhanced photopharmacology.

We investigated the feasibility of creating cyclic azobenzene/azobenzene-based photo-switchable drugs that can fine-tune antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) with light dependence. Furthermore, a "light-controlled drug combination" of these obtained drugs could be reversibly controlled to efficiently improve the antibiotic effect so as to reduce the minimum inhibitory concentrations (MICs) with different wavelength light illumination. Importantly, their antimicrobial activity could be easily manipulated by using light in bacterial patterning studies with high spatiotemporal precision, which might allow for localized activation of drugs and provide an alternative solution for practical clinical application in photopharmacology.

Bi3+/Sm3+ co-doped LiTaO3 photochromic perovskites: an ultrafast erasable optical information storage medium

LiTaO3:Bi3+/Sm3+ materials exhibit reversible color changes under different wavelength light irradiation, and have an ultra fast photobleaching rate of ~1 s.

Surface plasmon enhanced ultrathin Cu2ZnSnS4/crystalline-Si tandem solar cells.

Thin-film silicon solar cells have sparked a great deal of research interest because of their low material usage and cost-effective processing. Despite the potential benefits, thin-film silicon solar cells have low power-conversion efficiency, which limits their commercial usage and mass production. To solve this problem, we design an ultrathin dual junction tandem solar cell with Cu2ZnSnS4 (CZTS) and crystalline silicon (c-Si) as the main absorbing layer for the top and bottom cells, respectively, through optoelectronic simulation. To enhance light absorption in thin-film crystalline silicon, we use silver nanoparticles at the rear end of the bottom cell. We utilize amorphous Si with a c-Si heterojunction to boost the carrier collection efficiency. Computational analyses show that within 9 μm thin-film c-Si, we achieve 28.28% power conversion efficiency with a 220 nm top CZTS layer. These findings will help reduce the amount of Si (∼10 vs. ∼180 μm) in silicon-based solar cells while maintaining high power conversion efficiency.

Introducing luminescent solar waveguides for sustainable buildings for enhanced circadian rhythm regulation

As the world strives towards a low-carbon future, nearly-zero energy buildings (NZEB) have been the goal to reduce carbon emissions. Artificial lighting is estimated to consume as high as 40% of the total energy consumption in a commercial building. By utilising daylighting, which is the practice of allowing natural light into a building, energy consumption by artificial lighting can be reduced. Luminescent solar concentrators (LSCs) can act as a collector and waveguide to transport outdoor light into the building through total internal reflection. Besides, LSCs absorb a part of the solar spectrum and shift them to different wavelengths through up-conversion or down-conversion. Thus, the output spectrum can be manipulated for the desired indoor applications. Circadian rhythm is the periodic variations in behaviour that follows a 24-hour cycle, which is mainly regulated by light response. A regulated circadian rhythm is important for a healthy life, whereas a disturbed circadian rhythm can lead to health issues such as insomnia and mood disorders. There has been a consensus that our circadian rhythm strongly responds to shorter wavelength light, corroborated in studies. Thus, manipulating the output light of LSCs to contain larger proportions of light with shorter wavelengths could enhance circadian regulation. LSC devices have the potential to transport sufficient daylight up to 5m deep into the building, achieving areas beyond the reach of windows. Thus, LSCs can serve as a tool for daylighting purposes, regulating circadian rhythm and providing sufficient light for comfortable indoor visibility.

In Vivo Analysis of Heterogeneous Extracellular Vesicles Using a Red-Shifted Bioluminescence Resonance Energy Transfer Reporter Protein.

Current methods for characterizing the biodistribution of extracellular vesicles (EVs) are not sensitive enough to track EVs in vivo, despite significant advances over the past decade. Commonly used lipophilic fluorescent dyes are convenient, but lack specificity and yield inaccurate spatiotemporal images in the long-term tracking of EVs. In contrast, protein-based fluorescent or bioluminescent EV reporters have more accurately revealed their distribution in cells and mouse models. Here, we describe a red-shifted bioluminescence resonance energy transfer (BRET) EV reporter, PalmReNL, to analyze the trafficking of small EVs (<200nm; sEVs) and medium/large EVs (>200nm; m/lEVs) in mice. Its advantages are that (i) background signals in bioluminescence imaging (BLI) are negligible and (ii) the photons PalmReNL emits have spectral wavelengths longer than 600nm and can more efficiently penetrate tissues than reporters emitting shorter wavelength light.

Application of Absorption Spectra to Study Order of Sequence in Intersecting Printed and Pen Strokes

This work is performed to establish chronological order in crossing strokes between printed stroke and pen strokes. Nine different types of pens including cello maxriter pen (black and blue), pilot pen (red and black), cello pointec pen (black and blue) and cello techno tip pen (red, black and blue) are used to produce pen strokes and for printed stroke Canon LBP 3300 printer is used. In the case of printed stroke, only black color stroke is applied. As a result, samples of both homogeneous and heterogeneous intersecting strokes are prepared. This work is based on the assumption that nature and peak characteristics of absorption spectra from crossing stroke should be similar to that of second stroke. Here, absorption spectra is generated by Video Spectral Comparator-6000 by using light of wavelength ranging from 400 nm to 1000 nm. From this experiment, it is found to be possible to find chronological order for heterogeneous crossing strokes (crossing stroke of different colors) only if printed stroke is over pen stroke. It means, only if print is done over writing strokes from red and blue pen, then order of sequence of writing can be determined whereas in other cases it is not possible.

Blue-light-blocking films enabled by optimal absorption in plasmonic nanoparticles

The widespread use of light emitting diode (LED) based devices makes us inevitably exposed to a blue-enriched environment and brings a potential risk to our eyes. Developing a blue-light-blocking filter with narrow absorbing band, so as to only block harmful blue light (415–455 nm) is highly expected. Here, we create a blue-light-blocking film, consisting of a transparent medium embedded with plasmonic nanoparticles (NPs) that selectively absorb harmful blue light. We present the optimal design based on Mie theory by comprehensive scanning of the parametric space for the NPs, and experimentally demonstrate this concept with a blue-light-blocking film made of silver NPs in a polymer matrix by a simple solvothermal method. For the case of the silver NPs content ∼0.16 wt%, the film can block harmful blue light ∼65% at λ 0 ≈ 430 nm, while maintaining high transparency for the long wavelength light (λ 0 > 500 nm). We also demonstrate that it is possible to correct color cast by optimizing the design of the plasmonic NPs with sharp absorption resonances at yellow waveband. This method has attractive features including simplicity, low cost, non-toxic and scalability to large sizes, which makes it beneficial for blue-light-blocking applications.

Visible‐Light‐Switchable Tellurium‐Based Chalcogen Bonding: Photocontrolled Anion Binding and Anion Abstraction Catalysis

AbstractExploring new noncovalent bonding motifs with reversibly tunable binding affinity is of fundamental importance in manipulating the properties and functions of supramolecular self‐assembly systems and materials. Herein, for the first time, we demonstrate a unique visible‐light‐switchable telluro‐triazole/triazolium‐based chalcogen bonding (ChB) system in which the Te moieties are connected by azobenzene cores. The binding strengths between these azo‐derived ChB receptors and the halide anions (Cl−, Br−) could be reversibly regulated upon irradiation by visible light of different wavelengths. The cis‐bidentate ChB receptors exhibit enhanced halide anion binding ability compared to the trans‐monodentate receptors. In particular, the telluro‐triazolium‐based ChB receptor can achieve both high and significantly photoswitchable binding affinities for halide anions, which enable it to serve as an efficient photocontrolled organocatalyst for ChB‐assisted halide abstraction in a Friedel–Crafts alkylation benchmark reaction.

Visible-Light-Switchable Tellurium-Based Chalcogen Bonding: Photocontrolled Anion Binding and Anion Abstraction Catalysis.

Exploring new noncovalent bonding motifs with reversibly tunable binding affinity is of fundamental importance in manipulating the properties and functions of supramolecular self-assembly systems and materials. Herein, for the first time, we demonstrate a unique visible-light-switchable telluro-triazole/triazolium-based chalcogen bonding (ChB) system in which the Te moieties are connected by azobenzene cores. The binding strengths between these azo-derived ChB receptors and the halide anions (Cl- , Br- ) could be reversibly regulated upon irradiation by visible light of different wavelengths. The cis-bidentate ChB receptors exhibit enhanced halide anion binding ability compared to the trans-monodentate receptors. In particular, the telluro-triazolium-based ChB receptor can achieve both high and significantly photoswitchable binding affinities for halide anions, which enable it to serve as an efficient photocontrolled organocatalyst for ChB-assisted halide abstraction in a Friedel-Crafts alkylation benchmark reaction.

More light components and less light damage on rats' eyes: evidence for the photobiomodulation and spectral opponency.

The blue-light hazard (BLH) has raised concerns with the increasing applications of white light-emitting diodes (LEDs). Many researchers believed that the shorter wavelength or more light components generally resulted in more severe retinal damage. In this study, based on the conventional phosphor-coated white LED, we added azure (484nm), cyan (511nm), and red (664nm) light to fabricate the low-hazard light source. The low-hazard light sources and conventional white LED illuminated 68 Sprague-Dawley (SD) rats for 7 days. Before and after light exposure, we measured the retinal function, thickness of retinal layers, and fundus photographs. The expression levels of autophagy-related proteins and the activities of oxidation-related biochemical indicators were also measured to investigate the mechanisms of damaging or protecting the retina. With the same correlated color temperature (CCT), the low-hazard light source results in significantly less damage on the retinal function and photoreceptors, even if it has two times illuminance and blue-light hazard-weighted irradiance ([Formula: see text]) than conventional white LED. The results illustrated that [Formula: see text] proposed by IEC 62471 could not exactly evaluate the light damage on rats' retinas. We also figured out that more light components could result in less light damage, which provided evidence for the photobiomodulation (PBM) and spectral opponency on light damage.

Image blurring and spectral drift in imaging spectrometer system with an acousto-optic tunable filter and its application in UAV remote sensing

ABSTRACT In the design and research of an unmanned aerial vehicle-borne hyperspectral imager with an acousto-optic tunable filter (AOTF), the depth of the field range of the imaging objective lens is fixed, the spectral range of 400–1000nm is wide, and the AOTF crystal has different deflection angles for diffracted light of different wavelengths. These features all cause problems such as image blurring and spectral drifts. Therefore, we propose a solution using a tunable zoom lens and multi-modal spectrum registration to solve these problems. We also propose an improved image definition evaluation function using the zoom lens to obtain clear horizontal lines and blurred vertical lines and, thereby, hope to overcome image blurring in an AOTF spectrometer. The zoom parameters corresponding to the clear image in each spectral segment of the AOTF spectrometer can be determined rapidly and accurately. However, it is difficult to establish a mathematical model of the drift, using wavelength as a variable, to compensate the drift due to the clear image of each spectrum obtained using the zoom lens. The calibration method completes the registration of the spectral data cube composed of clear images, solving the problem of spectral band drift. Moreover, it has been verified through UAV-borne hyperspectral imaging that image blurring and spectral drift of the AOTF imaging spectrometer were significantly reduced, providing opportunities for the application and research of AOTF-based hyperspectral imagers in more fields, such as remote sensing.

Spectrally programmable Raman fiber laser with adaptive wavefront shaping

Raman fiber lasers (RFLs) have broadband tunability due to cascaded stimulated Raman scattering, providing extensive degrees of freedom for spectral manipulation. However, the spectral diversity of RFLs depends mainly on the wavelength flexibility of the pump, which limits the application of RFLs. Here, a spectrally programmable RFL is developed based on two-dimensional spatial-to-spectral mapping of light in multimode fibers (MMFs). Using an intracavity wavefront shaping method combined with genetic algorithm optimization, we launch light with a selected wavelength(s) at MMF output into the active part of the laser for amplification. In contrast, the light of undesired wavelengths is blocked. We demonstrate spectral shaping of the high-order RFL, including a continuously tunable single wavelength and multiple wavelengths with a designed spectral shape. Due to the simultaneous control of different wavelength regions, each order of Raman Stokes light allows flexible and independent spectral manipulation. Our research exploits light manipulation in a fiber platform with multi-eigenmodes and nonlinear gain, mapping spatial control to the spectral domain and extending linear light control in MMFs to active light emission, which is of great significance for applications of RFLs in optical imaging, sensing, and spectroscopy.

Photochemical Optimization of a Silver Nanoprism/Graphene Oxide Nanocomposite's Antibacterial Properties.

Optimizing the antibacterial properties of nanocomposites is a fundamental challenge for many biomedical applications. Here, we study how we may optimize the antibacterial activity of narrow-sized anisotropically flat silver nanoprisms (S-NPs) on graphene oxide (GO) against Escherichia coli. To do so, we transformed silver nanoparticles (AgNPs) into S-NPs and anchored them to GO via a facile and low-cost photochemical reduction method by varying the irradiation wavelength during the synthesis process in the visible range (440 to 650 nm and white light). We performed a physicochemical characterization of the resulting S-NP/GO nanocomposite using a combination of UV-vis spectroscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Our results reveal a synergistic effect between the silver nanoprism and the oxygen functional groups of the GO surface. The antibacterial activity of the S-NPs/GO nanocomposite shows a significantly higher 53% inhibition efficiency after being irradiated with a 540 nm wavelength light source, compared to AgNPs with a 1% inhibition efficiency, respectively. In so doing, we have demonstrated the utility of a low-cost photoreduction method to control the structural properties of silver nanoprism on GO and, in this way, enhance the antibacterial properties of the nanocomposite. These results should be of great interest in a wide range of biomedical applications and medical devices.

Long wavelength light reduces the negative consequences of dim light at night

Many patients with autism spectrum disorders (ASD) show disturbances in their sleep/wake cycles, and they may be particularly vulnerable to the impact of circadian disruptors. We have previously shown that a 2-weeks exposure to dim light at night (DLaN) disrupts diurnal rhythms, increases repetitive behaviors and reduces social interactions in contactin-associated protein-like 2 knock out (Cntnap2 KO) mice. The deleterious effects of DLaN may be mediated by intrinsically photosensitive retinal ganglion cells (ipRGCs) expressing the photopigment melanopsin, which is maximally sensitive to blue light (480 nm). In this study, the usage of a light-emitting diode array enabled us to shift the spectral properties of the DLaN while keeping the intensity of the illumination at 10 lx. First, we confirmed that the short-wavelength enriched lighting produced strong acute suppression of locomotor activity (masking), robust light-induced phase shifts, and cFos expression in the suprachiasmatic nucleus in wild-type (WT) mice, while the long-wavelength enriched lighting evoked much weaker responses. Opn4DTA mice, lacking the melanopsin expressing ipRGCs, were resistant to DLaN effects. Importantly, shifting the DLaN stimulus to longer wavelengths mitigated the negative impact on the activity rhythms and ‘autistic’ behaviors (i.e. reciprocal social interactions, repetitive grooming) in the Cntnap2 KO as well as in WT mice. The short-, but not the long-wavelength enriched, DLaN triggered cFos expression in in the basolateral amygdala (BLA) as well as in the peri-habenula region raising that possibility that these cell populations may mediate the effects. Broadly, our findings are consistent with the recommendation that spectral properties of light at night should be considered to optimize health in neurotypical as well as vulnerable populations.

Numerical modeling of nonlinear photoelasticity

AbstractWhen molecular photo‐switches, such as azobenzene or norbornadiene, are embedded into a sufficiently soft polymer matrix the resulting compound can undergo a mechanical deformation induced by light of a specific wavelength. These photo‐sensitive compounds have the potential to be applied as soft actuators without the need for hard wired electronics or a separate energy source. Such characteristics are especially attractive in the design of micro‐scale robots but also other applications such as high‐speed data transfer or the conversion of photonic energy into a mechanical response holds great promise. Despite these almost futuristic possibilities, photo‐sensitive polymers have not yet experienced a sufficient attention in industrial applications. One important factor to increase the acceptance of this group of soft smart materials is the formulation of a rigorous constitutive modeling approach in combination with numerical simulation methods. Thus, in this contribution we present a photo‐mechanical modeling approach, departing from the fundamentals published previously. We briefly introduce the necessary constitutive equations which are subsequently utilized in combination with the respective balance laws into a finite element implementation. Finally, the capabilities of the numerical solution approach are illustrated by a simple two‐dimensional bench‐mark example and subsequently extended to a more complex three‐dimensional problem.

Psoralen as a Photosensitizers for Photodynamic Therapy by Means of In Vitro Cherenkov Light

Possible enhancements of DNA damage with light of different wavelengths and ionizing radiation (Rhenium-188-a high energy beta emitter (Re-188)) on plasmid DNA and FaDu cells via psoralen were investigated. The biophysical experimental setup could also be used to investigate additional DNA damage due to photodynamic effects, resulting from Cherenkov light. Conformational changes of plasmid DNA due to DNA damage were detected and quantified by gel electrophoresis and fluorescent staining. The clonogene survival of the FaDu cells was analyzed with colony formation assays. Dimethyl sulfoxide was chosen as a chemical modulator, and Re-188 was used to evaluate the radiotoxicity and light (UVC: λ = 254 nm and UVA: λ = 366 nm) to determine the phototoxicity. Psoralen did not show chemotoxic effects on the plasmid DNA or FaDu cells. After additional treatment with light (only 366 nm-not seen with 254 nm), a concentration-dependent increase in single strand breaks (SSBs) was visible, resulting in a decrease in the survival fraction due to the photochemical activation of psoralen. Whilst UVC light was phototoxic, UVA light did not conclude in DNA strand breaks. Re-188 showed typical radiotoxic effects with SSBs, double strand breaks, and an overall reduced cell survival for both the plasmid DNA and FaDu cells. While psoralen and UVA light showed an increased toxicity on plasmid DNA and human cancer cells, Re-188, in combination with psoralen, did not provoke additional DNA damage via Cherenkov light.

태양이 피부에 닿으면

Skin is the primary barrier that protects our body from various external factors. Sunlight is a representative environmental factor that greatly affects the physiological activities of our body, and for this, sunlight touches the skin. In fact, many studies have thoroughly investigated the harmful effects of ultraviolet (UV) on the skin and their mechanisms. Chronic exposure to UV commonly causes damage to the skin, eventually leading to wrinkle formation and loss of skin elasticity. Recently, it has been discovered that visible light of different wavelengths has various biological effects on the skin. In addition, recent studies have reported that photoreceptors are expressed not only in the eyes but also in the skin, and sunlight is emerging as a new topic for skin research. Since research on the visible light region of the skin is still in its infancy, research has been conducted with different equipment and methods for each study. Therefore, results that contradict existing results or are difficult to accept are reported. Ultimately, standardization of highly reproducible equipment, specifications, and methods for light research seems to be absolutely necessary for future.

Characterisation of pupillary responses to alternating blue and orange light exposures in a fMRI protocol

AbstractBackgroundThe non‐image forming (NIF) functions of light are diverse and include stimulation of cognition and alertness, sleep regulation and pupil diameter modulation. Previous work indicated that exposure to blue‐enriched light as well as pupil size variations are associated with higher locus coeruleus (LC) activity. Given the central role of LC structure and function in the earliest stages of Alzheimer’s disease neuropathology, light exposure may constitute a promising stimulation technique to delay disease progression. Prior to addressing light impact on the LC, here, we aimed at characterising the pupil responses to light during fMRI protocol, to determine its quality in assessing NIF effects of light.MethodPupil diameter was continuously recorded in 11 healthy subjects (20‐30yr, 7 women) with an infrared eyetracker device while they were administered a 15‐min auditory oddball task in a 7T MRI scanner. Participants were concomitantly exposed to pseudo‐randomly alternating 30s blocks of blue‐enriched (4,000K; 200µW/cm2) and orange (589nm; 6x1013photons/cm2/s) lights. Statistics consisted in generalized linear mixed models seeking effects of light condition on pupil response, with subjects as random intercept and controlling for age, sex and BMI.ResultBlue light condition was associated with a significantly smaller pupil diameter as compared to the orange condition, (main effect of light condition: F(2,270)=571.22;p&lt;.0001; Fig1). Moreover, the impact of the light condition on pupil size did not significantly change over the 15min‐protocol (light condition x block repetition interaction: F(12,240)=1.21 ; p=.28), suggesting that time‐in‐protocol and prior light blocks did not influence pupil constriction.ConclusionWe report preliminary results confirming that blue‐enriched light triggers a stronger pupil response than longer wavelength light and showing that the protocol induces a stable response in time even when using short alternating light exposures. These findings support the validity of the protocol to assess NIF responses to light in fMRI in healthy participants, including over the LC. Being able to stimulate the LC holds important implications for possibly delaying Alzheimer’s disease progression. We now aim to include more participants, including older individuals, and to extend to other cognitive tasks to assess the generalization of the present findings to other cognitive domains and age‐ranges.