Wavelength Of Visible Light Research Articles

Transparent X-ray Shielding Solutions with Various Metal Ions.

We fabricated transparent, Pb-free X-ray shielding materials using solvated ions in a polar solvent. Previous materials have been based on dispersions of metal-containing particles such as barium sulfate (BaSO4) in a matrix. Comparisons of suspensions of metal-based particles and solutions of metal ions in a solvent enable better understanding of interactions such as reflection, scattering, and absorption between X-rays and substances. The X-ray shielding properties of a solution of solvated metal ions were similar to or better than those of suspensions of metal-containing particles. In addition, the metal-ion solutions exhibited high transparency. The most effective material among those investigated for X-ray shielding was barium bromide (BaBr2), which exhibits high solubility in polar solvents. X-ray shielding of 92% was confirmed at a tube voltage of 120 kV, along with ∼90% UV transmittance at a visible-light wavelength of 400 nm. Thus, both high X-ray shielding performance and high transparency were achieved.

Z-Schematic Water Splitting on Photocatalyst Sheets Composed of Transition-Metal-Doped Metal Oxides with Long Wavelength Visible Light Responses and a Conductive Polymer

Z-Schematic Water Splitting on Photocatalyst Sheets Composed of Transition-Metal-Doped Metal Oxides with Long Wavelength Visible Light Responses and a Conductive Polymer

Preparation and characterization of Epoxy/TiO2 thin films for Anti-UVB coating

Thin films of pure epoxy and Epoxy/TiO2 were successfully prepared using the spin coating method. The epoxy was doped with different weight ratios of TiO2 nanoparticles for the purpose of studying the effect of increasing its percentage on the properties of epoxy thin films. The surface topography of the prepared films was studied using an atomic force microscope (AFM), which showed that the surfaces of the samples became rougher with an increase in the doping of TiO2 nanoparticles. The functional groups were measured using a Fourier infrared spectrometer (FTIR), which showed the presence of TiO2 bonds in the epoxy matrix at wave numbers 400 and 862 cm-1. Optical measurements for absorbance, transmittance, and reflectivity showed a clear effect of TiO2 nanoparticles on the optical properties of the prepared samples through high absorbance for ultraviolet ray’s B (UVB) and low absorbance for visible light. Reflectivity decreases at the wavelengths of UVB and increases at the wavelengths of visible light with an increasing doping ratio. This makes these thin films candidates for use in anti-UVB coatings.

Long wavelength near-infrared and red light-driven consecutive photo-induced electron transfer for highly effective photoredox catalysis

Consecutive photoinduced electron transfer (conPET) processes accumulate the energies of two photons to overcome the thermodynamic limit of traditional photoredox catalysis. However, the excitation wavelength of conPET systems mainly focused on short wavelength visible light, leading to photodamage and incompatibility with large-scale reactions. Herein, we report on conPET systems triggered by near-infrared (NIR) and red light. Specifically, a blue-absorbing conPET photocatalyst, perylene diimide (PDI) is sensitized by a palladium-based photosensitizer to triplet excited state (3PDI*), which generates PDI radical anion (PDI•–) over 100-fold faster than that in the conventional conPET. Accordingly, photoreduction with superior reaction rate and penetration depth, as well as reduced photodamage is detected. More importantly, our work offers comprehensive design rules for the triplet-mediated conPET strategy, whose versatility is confirmed by metal-free dye pairs and NIR-active PtTNP/PDI. Notably, our work achieves NIR-driven atom transfer radical polymerization using an inert aromatic halide as the initiator.

A Halogen‐Bonded Fluorescent Molecular Photoswitch: Transition from 3D Cubic Lattice to 1D Helical Superstructure for Polarization Inversion of Circularly Polarized Luminescence

AbstractThe fabrication of materials that can switch between circularly polarized luminescence (CPL) signals is both essential and challenging. Here, two new halogen‐bonded fluorescent molecular photoswitches, namely, HB‐switch 1 and HB‐switch 2, containing α‐cyano‐substituted diarylethene compounds with different end groups were developed. Upon exposure to specific UV or visible light wavelengths, they exhibited controllable and reversible Z/E photoisomerization. When these switches were integrated into blue‐phase liquid crystals (BPLCs), the temperature range of BP significantly expanded. Notably, the BP system incorporating HB‐switch 1 exclusively achieved reversible polarization inversion of CPL signals under irradiation with specific UV/Visible light and during cooling/heating. The photo/thermal dual‐response behavior of the CPL signals can be attributed to the phase transition from a high‐symmetry 3D BP Icubic lattice to a low‐symmetry 1D helical superstructure induced by the Z/E photoisomerization of HB‐switch 1 and temperature changes. This study underscores the significance of employing halogen‐bond assembly strategies to design materials with switchable CPL signals, opening new possibilities for CPL‐active systems.

A Halogen-Bonded Fluorescent Molecular Photoswitch: Transition from 3D Cubic Lattice to 1D Helical Superstructure for Polarization Inversion of Circularly Polarized Luminescence.

The fabrication of materials that can switch between circularly polarized luminescence (CPL) signals is both essential and challenging. Here, two new halogen-bonded fluorescent molecular photoswitches, namely, HB-switch 1 and HB-switch 2, containing α-cyano-substituted diarylethene compounds with different end groups were developed. Upon exposure to specific UV or visible light wavelengths, they exhibited controllable and reversible Z/E photoisomerization. When these switches were integrated into blue-phase liquid crystals (BPLCs), the temperature range of BP significantly expanded. Notably, the BP system incorporating HB-switch 1 exclusively achieved reversible polarization inversion of CPL signals under irradiation with specific UV/Visible light and during cooling/heating. The photo/thermal dual-response behavior of the CPL signals can be attributed to the phase transition from a high-symmetry 3D BP Icubic lattice to a low-symmetry 1D helical superstructure induced by the Z/E photoisomerization of HB-switch 1 and temperature changes. This study underscores the significance of employing halogen-bond assembly strategies to design materials with switchable CPL signals, opening new possibilities for CPL-active systems.

Activation of peroxymonosulfate under visible-light illumination for enhanced degradation of acetaminophen by self-assembly iron phosphorus/hexagonal tubular graphite carbon nitride

Improving the visible light response by sulfate-based advanced oxidation processes (S-AOPs) is a promising method for the efficient degradation of organic matter in water. Herein, we facilely fabricated the iron phosphorus/hexagonal tubular graphite carbon nitride (FeP/HTCN) composites via two-phase hydrothermal supramolecular self-assembly and thermal-condensation method. FeP/HTCN with the shape of hollow hexagonal tubular loaded iron phosphorus particles was first synthesized. The results suggested that the loading of iron phosphate greatly enhanced its ability to activate peroxymonosulfate (PMS) while also improving the photocatalytic ability of the catalyst due to its smaller bandgap. The combined effect of iron phosphate, HTCN, and visible light (wavelength ≥ 420 nm) assistance facilitated the enhancement of the reaction activity. Electron paramagnetic resonance techniques (EPR) and radial quenching experiments validated that singlet oxygen (1O2) derived from superoxide was the main active species. The degradation pathways of acetaminophen (APAP) were determined and the mechanism of mineralization and decomposition was demonstrated. This work provided a proposal for the application of iron salts represented by iron phosphate in S-AOPs.

Enhancing mechanical strength in thermosensitive Poly(tetrabutylphosphonium styrene sulfonate) (PTPSS) hydrogels through acrylamide (AAm) copolymerization

Thermosensitive hydrogels are lauded for their smart and tunable responsive behavior, presenting critical application potential in biomedicine and sensing technologies. Traditional thermo-responsive polymers, such as poly(N-isopropylacrylamide) (PNIPAM), typically manifest subpar electrical conductivity, which hinders their integration into biosensing applications. PTPSS hydrogel distinctively responses to temperature and repeatably endures large volume water flux under temperature changes, while catering a significant conductivity (7.438 mS cm−1). However, it possesses suboptimal mechanical strength. In this research, we enhanced the mechanical strength of PTPSS hydrogel by copolymerization of AAm, obtaining a 22-fold increase in compression yield stress and a yield strain reaching up to 75 % The copolymerized hydrogel showcases an elevated transmittance ranging from 86.3–97.1 % within the visible light wavelength spectrum, with the copolymerized hydrogel's conductivity being about 188 times that of PNIPAM copolymerized hydrogel at identical monomer proportions. Simultaneously, the hydrogel maintains explicit thermosensitivity even at a TPSS ratio as low as 60 wt% (grounded on the overall monomer sum). The introduction of AAm copolymerization awards PTPSS with robust mechanical properties, profound transparency, and striking thermosensitivity alongside high conductivity, endorsing enormous potential in the realm of intelligent sensing.

A low cost and simple webcam spectrometer for exploring the visible wavelengths of light

This paper presents a method for constructing a simple, cost-effective, and versatile spectrometer using readily available materials such as a basic webcam, a DVD, tin foil, a cardboard tube, and a microphone boom arm. Building upon previous designs (Widiatmoko et al 2011 Phys. Educ. 46 332, Lorenz 2014 Am. J. Phys. 82 169–73, Rodrigues et al 2016 Phys. Educ. 51 014002, Likith et al 2021 J. Opt. 50 489–94), this spectrometer is mounted on a microphone boom arm, enhancing flexibility in capturing spectra from various angles and distant light sources. The spectrometer, coupled with Theremino Spectrometer V3.1 software, achieves sufficient resolution to measure solar Fraunhofer lines and closely spaced Mercury double lines at 436 nm and 577 nm. The procedure for assembling the spectrometer is detailed, including calibration using a Mercury CFL lamp or phone screens. Results demonstrate the spectrometer’s capability to capture high-resolution spectra of the blue sky and light sources, identifying significant spectral lines. This DIY spectrometer offers an accessible tool for amateur scientists and educators to explore visible light spectra, facilitating both qualitative and quantitative analyses. Also, through measuring the light from phone screens work, perception of colour can be explored.

Building Energy Efficiency Enhancement through Thermochromic Powder-Based Temperature-Adaptive Radiative Cooling Roofs

This paper proposes a temperature-adaptive radiative cooling (TARC) coating with simple preparation, cost effectiveness, and large-scale application based on a thermochromic powder. To determine the energy efficiency of the proposed TARC coating, the heat transfer on the surface of the TARC coating was analyzed. Then, a typical two-story residential building with a roof area of 258.43 m2 was modeled using EnergyPlus. Finally, the energy-saving potential and carbon emission reduction resulting from the application of the proposed TARC roof in buildings under different climates in China were discussed. The results showed that the average solar reflectivity under visible light wavelengths (0.38–0.78 μm) decreases from 0.71 to 0.37 when the TARC coating changes from cooling mode to heating mode. Furthermore, energy consumption can be reduced by approximately 17.8–43.0 MJ/m2 and 2.0–32.6 MJ/m2 for buildings with TARC roofs compared to those with asphalt shingle roofs and passive daytime radiative cooling (PDRC) roofs, respectively. This also leads to reductions in carbon emissions of 9.4–38.0 kgCO2/m2 and 1.0–28.9 kgCO2/m2 for the buildings located in the selected cities. To enhance building energy efficiency, TARC roofs and PDRC roofs are more suitable for use on buildings located in zones with high heating demands and high cooling demands, respectively.

Spontaneous chiral symmetry breaking in polar fluid–heliconical ferroelectric nematic phase

Spontaneous mirror symmetry breaking by formation of chiral structures from achiral building blocks and emergent polar order are phenomena rarely observed in fluids. Separately, they have both been found in certain nematic liquid crystalline phases; however, they have never been observed simultaneously. Here, we report a heliconical arrangement of achiral molecules in the ferroelectric nematic phase. The phase is thus spontaneously both polar and chiral. Notably, the pitch of the heliconical structure is comparable to the wavelength of visible light, giving selective reflection controllable by temperature or application of a weak electric field. Despite bearing resemblance to the heliconical twist-bend nematic phase, this chiral ferroelectric nematic phase arises from electrical interactions that induce a noncollinear orientation of electric dipoles.

Synthesis and Study of Building Blocks with Dibenzo[b,f]oxepine: Potential Microtubule Inhibitors.

The synthesis of biphenylmethoxydibenzo[b,f]oxepine or photoswitchable fluorinated dibenzo[b,f]oxepine derivatives with one or three azo bonds, potential microtubule inhibitors, is described. Our studies provide a concise method for constructing derivatives containing the dibenzo[b,f]oxepine skeleton. An analysis of products was run using experimental and theoretical methods. Next, we evaluated the E/Z isomerization of azo-dibenzo[b,f]oxepine derivatives, which could be photochemically controlled using visible-wavelength light.

Mobile fronthaul solution based on visible light fiber communication and zero-padding 8-D CAP modulation.

With the deployment of the fifth-generation (5 G) emerging technologies, such as massive multiple-input multiple-output (mMIMO), conventional mobile fronthaul (FH) schemes based on Common Public Radio Interface (CPRI) are limited in their abilities to support ultra-high data rate, large bandwidth and massive connectivity. This has led to a growing demand for alternative solutions that can better fulfill these requirements. Visible light communication (VLC) has recently gained increasing research interest as a potential complementary technology for beyond-5 G communication, offering advantages such as unlicensed and abundant spectrum, high bandwidth and cost-efficiency. In this paper, we propose a novel mobile fronthaul solution based on visible light fiber communication (VLFC), incorporating innovative zero-padding N-D (N>2) carrierless amplitude and phase (CAP) modulation. To avoid strong low-frequency noise (LFN) in the practical VLFC system, we innovatively propose zero-padding N-D CAP based on the actual distribution of LFN for the first time. In contrast to frequency division multiplexing (FDM), N-D CAP eliminates guard bands and ensures similar performance among multiple channels. To prove the concept, we demonstrate the transmission of PAM8 symbols at three typical visible light wavelengths (R/G/B) over 100 m multi-mode fiber (MMF) using zero-padding 8-D CAP modulation. The experiment verifies that zero-padding significantly enhances communication performance, with all 8 channels achieving similar BER. Communication performance improves as wavelengths are longer due to attenuation and dispersion caused by MMF. Finally, we have achieved a total data rate of 10.8Gbps at 635 nm (red), 9.0Gbps at 520 nm (green), and 7.5Gbps at 488 nm (blue) under the 7% HD-FEC threshold.

Antibacterial activity of 3D printed thermoplastic elastomers doped with carbon quantum dots for biomedical applications

3D printing provides a lot of varieties for the manufacturing of personalized biomedical devices. Incorporation of the nanoparticles with potential antibacterial activity to the printed materials is another added value. One example of such nanoparticles are hydrophobic carbon quantum dots (hCQDs), which are zero-dimensional redox-active materials with high chemical stability and low production costs. They produce singlet oxygen only when activated by a specific wavelength of visible blue light which allows for controlled antibacterial action and minimizes the chances of bacterial resistance emergence. We prepared and characterized polymer composites based on thermoplastic elastomers (TPE) doped with hCQDs (TPE/hCQDs). The composites were 3D printed using fused deposition modeling method. In the first set of samples, a filament of pure TPE was immersed in a solution of hCQDs (0.5 mg/mL), then 3D printed, and compared with unmodified TPE filament. The mechanical properties, swelling behavior, hardness, and thermal stability of TPE/hCQDs were compared with the pure TPE printed samples. The production of singlet oxygen was confirmed by the electron paramagnetic resonance method. The antibacterial activity of the samples was tested according to ISO 22196 against Staphylococcus aureus and Escherichia coli after one hour of exposure to blue light, which completely inhibited bacterial growth. Besides, the cytotoxicity of samples was evaluated by MTT assay, and no significant effect of the materials on cell viability was observed. 3D printed materials with antibacterial activity represent a perspective for the future, especially in the field of personalized medicine, as well as in products for other industries.

Evaluating hyperpigmentation: is invasion of the skin necessary?

BackgroundThe combination of long wavelength ultraviolet A1 radiation (LWUVA1) and visible light (VL) has been shown to produce photodamage and the majority of organic sunscreens lack protection against this spectrum. Currently, established testing protocols for VL photoprotection are lacking.ObjectiveTo compare pigmentation assessment methods, including Investigator’s Global Assessment (IGA) scoring, Diffuse Reflectance Spectroscopy (DRS), and immunohistochemistry, to assess the utility of each in evaluating VL + LWUVA1 induced pigmentation.MethodsAnonymized IGA, DRS, and immunohistochemistry data for 37 subjects (Fitzpatrick skin phototypes IV-VI) was retrospectively analyzed for pigment evaluation. Pigmentation was induced on the subjects’ backs with VL + LWUVA1 (0%–0.5% UVA1) irradiation at a dose of 480 J/cm2. Comparisons were made for all three assessment techniques between non-irradiated skin and VL + LWUVA1 irradiated skin, as well as between pure VL (0% UVA1) and VL + LWUVA1 (0.5% UVA1) irradiated sites. All comparisons were made for data collected approximately 24 h after irradiation to evaluate persistent pigment darkening (PPD).ResultsAmong all 37 subjects, both IGA scores and DRS detected a statistically significant difference in PPD between irradiated and non-irradiated sites, as well as between VL + LWUVA1 and pure VL irradiated sites. However, MART-1/Melan-A did not indicate a statistically significant difference in PPD between irradiated and non-irradiated sites or between VL + LWUVA1 and pure VL irradiated sites.ConclusionSubjective and objective noninvasive assessments were more sensitive in detecting VL + LWUVA1 induced pigmentation and should be preferred over invasive methods. Researchers are advised to initiate assessments with IGA and subsequently incorporate DRS for more objective and comprehensive insights in pigment evaluation.

Bio-Inspired Crystalline Core-Shell Guanine Spherulites.

Spherical particles with diameters within the wavelength of visible light, known as spherulites, manipulate light uniquely due to their spatial organization and their structural birefringence. Most of the known crystalline spherulites are branched, and composed of metals, alloys, and semi-crystalline polymers. Recently, a different spherulite architecture is discovered in the vision systems of decapod crustaceans - core-shell spherulites composed of highly birefringent ( ) organic single-crystal platelets, with exceptional optical properties. These metastructures, which efficiently scatter light even in dense aqueous environments, have no synthetic equivalence and serve as a natural proof-of-concept as well as synthetic inspiration for thin scattering media. Here, the synthesis of core-shell spherulites composed of guanine crystal platelets (( ) is presented in a two-step emulsification process in which a water/oil/water emulsion and induced pH changes are used to promote interfacial crystallization. Carboxylic acids neutralize the dissolved guanine salts to form spherulites composed of single, radially stacked, β-guanine platelets, which are oriented tangentially to the spherulite surface. Using Mie theory calculations and forward scattering measurements from single spherulites, it is found that due to the single-crystal properties and orientation, the synthetic spherulites possess a high tangential refractive index, similarly to biogenicparticles.

Diamond-lattice photonic crystals assembled from DNA origami.

Colloidal self-assembly allows rational design of structures on the micrometer and submicrometer scale. One architecture that can generate complete three-dimensional photonic bandgaps is the diamond cubic lattice, which has remained difficult to realize at length scales comparable with the wavelength of visible or ultraviolet light. In this work, we demonstrate three-dimensional photonic crystals self-assembled from DNA origami that act as precisely programmable patchy colloids. Our DNA-based nanoscale tetrapods crystallize into a rod-connected diamond cubic lattice with a periodicity of 170 nanometers. This structure serves as a scaffold for atomic-layer deposition of high-refractive index materials such as titanium dioxide, yielding a tunable photonic bandgap in the near-ultraviolet.

DEVELOPING NEXT-GENERATION INJECTABLE ADIPOSE TISSUE GRAFTS FOR SOFT-TISSUE RECONSTRUCTION

IntroductionAutologous fat grafting has favourable potential as a regenerative strategy and is the current gold-standard to repair large contour defects, as needed in breast reconstruction after mastectomy and traumatic soft tissue reconstruction. Clinically, there is a limit on the volume of lipoaspirate which can be utilised to repair a soft-tissue defect. Surgical complications are the result of poor structural fidelity of lipoaspirate and graft resorption as a filling material and are hindered further by poor graft vascularisation. This study aims to develop injectable lipoaspirate-derived adipose tissue grafts with enhanced biologically and clinically-admissible structural and functional properties adopting light photocrosslinking of unmodified lipoaspirate.MethodsPatient-derived lipoaspirate was harvested and crosslinked using novel photoinitiator and exposure to visible light (wavelength 450nm) in surgery, establishing bonds between extracellular matrix (ECM) proteins within the material. The degree of crosslinking was tuned (photoinitiator concentration, light exposure, light intensity) and covalent bond formation measured using mass spectrometry. To predict patient response, SWATH-MS was used to identify differences in patient ECM and crosslinked grafts were implanted in vivo using a subcutaneous mouse model. Functional vessel formation and resorption were quantified using micro-CT and tissue-remodelling was assessed via histology.ResultsThere was an increase in the relative abundance of covalent bonds present with increasing degree of crosslinking. When injected, crosslinked lipoaspirate had better shape fidelity compared with native lipoaspirate – demonstrated by a smaller fibre diameter. Crosslinked lipoaspirate remained viable over long term culture and resulted in more predictable resorption profiles when implanted in vivo.ConclusionsThe crosslinking approach described here is tunable and functional across different patient samples. Improving the structural properties of lipoaspirate through minimal manipulation has clinical utility for the delivery of grafts with higher shape fidelity and therefore increased graft survival when implanted.

Investigate the Electrical and Structural Characteristics of the Si-ZnO Diode

Silicon-zinc oxide (Si-ZnO) junction has been prepared using the chemical bath technique. The zinc oxide layer was examined using different techniques, including X-ray spectroscopy and a UV-visible spectrophotometer. The ZnO film images show that the films are homogeneous with an average grain size of 70 nm, while the X-ray spectrum shows that the layers are amorphous with some crystalline phase peaks appearing between 2θ=20° and 35°, which belong to ZnO. Transmittance, absorbance and extinction coefficient were varied over the visible light wavelength range, and the energy gap of the films was about 2.6 eV. In both forward and reverse bias, the junction revealed diode characteristics. The influence of light on the current intensity was evident and reached about 240 mA compared to the current intensity in the dark state. Also, the current intensity of the diode increased at each applied voltage with the increase in the intensity of the light shining on it.

Controls on the Respiration of Ancient Carbon Draining From Permafrost Soils Into Sunlit Arctic Surface Waters

AbstractThe thawing of ancient organic carbon stored in arctic permafrost soils, and its oxidation to carbon dioxide (CO2, a greenhouse gas), is predicted to amplify global warming. However, the extent to which organic carbon in thawing permafrost soils will be released as CO2 is uncertain. A critical unknown is the extent to which dissolved organic carbon (DOC) from thawing permafrost soils is respired to CO2 by microbes upon export of freshly thawed DOC to both dark bottom waters and sunlit surface waters. In this study, we quantified the radiocarbon age and 13C composition of CO2 produced by microbial respiration of DOC that was leached from permafrost soils and either kept in the dark or exposed to ultraviolet and visible wavelengths of light. We show that permafrost DOC most labile to microbial respiration was as old or older (ages 4,000–11,000 a BP) and more 13C‐depleted than the bulk DOC in both dark and light‐exposed treatments, likely indicating respiration of old, 13C‐depleted lignin and lipid fractions of the permafrost DOC pool. Light exposure either increased, decreased, or had no effect on the magnitude of microbial respiration of old permafrost DOC relative to respiration in the dark, depending on both the extent of DOC oxidation during exposure to light and the wavelength of light. Together, these findings suggest that photochemical changes affecting the lability of permafrost DOC during sunlight exposure are an important control on the magnitude of microbial respiration of permafrost DOC in arctic surface waters.