Blue Light Source Research Articles

Highly Productive Laser Annealing Manufacturing Method Using Continuous Blue WBC (Wavelength Beam Combining) Technique

Blue laser annealing can be used to obtain a high-mobility thin-film transistor (TFT) through a laser annealing (i.e., LTPS: low-temperature Poly-Si) process. However, the laser annealing process’s low productivity (as well as high cost) is an issue because the high output power of blue lasers still needs to be addressed. Therefore, productivity can be improved if blue laser energy is efficiently supplied during the laser annealing process using a continuous wave laser instead of a conventional pulsed excimer laser. We developed a blue laser light source (440 ± 10 nm) using the wavelength beam combining (WBC) method, which can achieve a laser power density of 73.7 kW/cm2. In this semiconductor laser, when the power was increased s by 2.9 times, the laser scanning speed was increased by 5.0 times, achieving twice the productivity of conventional lasers. After laser annealing, the size of the crystal grains varied between 2 and 15 μm, resulting in a crystallization rate of 100% by Raman scattering rsult and low resistivity of 0.04 Ωcm. This increase in production capacity is not an arithmetic increase with increased power but a geometric production progression.

Extracorporeal Photopheresis with 5-Aminolevulinic Acid in Crohn's Disease-A First-in-Human Phase I/II Study.

Background/Objectives: With the increasing prevalence of Crohn's disease (CD), treatment options for patients who fail conventional and advanced therapy are highly needed. Therefore, we explored the safety and efficacy of extracorporeal photopheresis (ECP) using 5-aminolevulinic acid (ALA) and blue light (405 nm). Methods: Patients with active CD who failed or were intolerant to biological therapy were eligible. Mononuclear cells (90 mL) were collected from each patient using a Spectra Optia® apheresis system and diluted with 100 mL of 0.9% sodium chloride in a collection bag. The cells were incubated with ALA at a concentration of 3 millimolar (mM) for 60 min ex vivo and illumination with an LED blue light (405 nm) source (BLUE-PIT®) before reinfusion to the patient. Recording of vital signs and adverse events were regularly performed. At week 13, we assessed the patients with colonoscopy, the Harvey Bradshaw Index (HBI), the Inflammatory Bowel disease Health Related Quality of Life Questionnaire, and the measurement of serum C-reactive protein and fecal calprotectin (FC) levels. Biopsies of the intestines were taken for immunohistochemistry. Results: Seven patients were included. Four patients completed the treatments, with a total of 24 treatments. Three of the four patients achieved a favorable response, including a lower HBI, lower FC levels, and/or endoscopic improvement. No significant adverse events were observed. The remaining three patients received only one, three, or five treatments due to technical difficulties, medical reasons, or the withdrawal of informed consent. Conclusions: ALA-based ECP appears safe and seems to give some clinical improvement for the patients with active CD who failed to respond to conventional and advanced therapies.

Blacklight sintering of BaZrO3-based proton conductors

Acceptor-doped BaZrO3, a ceramic proton conductor, is well researched for use in solid oxide fuel cells due to its proton conductivity and chemical stability. A major drawback of the material is the difficulty of sintering as it requires high sintering temperatures and long heating times (> 1600 °C, 24 h). An emerging sintering technology to mitigate this challenge is blacklight sintering, which uses a high-powered blue or UV light source to heat ceramics extremely fast leading to short sintering times and reduced energy demand. In this work, BaZr0.8Y0.2O3-δ (BZY20) and BaZr0.8Y0.1Sc0.1O3-δ (BZY10Sc10) were blacklight-sintered with a high-power blue laser in under four minutes. Even though the resulting samples have a gradient from large to small grains and structurally disordered grain boundaries, the proton conductivity is comparable to conventionally sintered samples. Hence, blacklight sintering is a promising technology with the potential to sinter BaZrO3 much faster, while saving energy.

The influence of blue light sources on somnological disorders among patients with mild to moderate acne

Background. The acne is a chronic inflammatory skin disease that affects all age groups of the population and has a serious impact on the quality of life of patients. Various endogenous and exogenous factors are involved in the pathogenesis of dermatosis. The increasing of usage of digital media and the Internet has an impact on people's sleep habits and, with changes in sleep quality, symptoms of depression, anxiety and stress may increase, which leads to a more severe course of chronic dermatoses, including acne. Aim. To evaluate the relationship between somnological disorders (SLD) and the frequency of smartphone use before bedtime in patients with mild to moderate acne (MMA). Materials and methods. A single-center observational prospective study was conducted from 2023 to 2024: 130 patients aged 18 to 30 years (average age 23.32±2.75 years) diagnosed with MMA were observed. The data on the severity of acne were assessed using the Global Acne Grading System (GAGS), the degree of sleep disturbance was determined using the Pittsburgh Sleep Quality Index (PSQI), and the quality of life of patients was determined according to the Dermatology Life Quality Index (DLQI). Taking into account indicators on the use of a smartphone with the iOS or Android operating system included calculating average screen time, assessing addiction and the fact of using a smartphone 1 hour before bedtime. The statistical processing was carried out using the Jamovi version 2.3.21 program. Results. The SLD were identified in 85 (65.38%) patients with MMA. The dermatosis had a strong impact on quality of life (DLQI20) in 82.31% (n=107). In group I of patients "poor sleeping" there was a direct correlation between SLD (PSQI) and the severity of dermatosis (ρ=0.533; p0.001) and the duration of screen time (ρ=0.628; p0.001) spent on a smartphone per day. The patients of group I had a greater dependence on a smartphone compared to group II of patients "well sleeping": 15.94±1.89 points versus 7.71±1.96 points (p0.001). Conclusion. It has been established that the level of SLD has a high incidence in the group of patients with MMA. There is a pronounced correlation between dyssomnia and the severity of dermatosis; in patients with disturbed sleep, a high dependence on the phone and a correlation with the duration of screen time spent on a smartphone per day were revealed. This study demonstrates the need to pay attention to the presence of disturbances in the quality of sleep in people suffering from skin diseases, in particular acne.

Single-photon-assisted two-photon polymerization

Light-based additive manufacturing (AM) has revolutionized the fabrication of complex three-dimensional objects offering a cost-effective and high-speed alternative to traditional machining. Single-photon polymerization is a key process in this advancement, providing rapid printing time, albeit with limited resolution in the range of tens of micrometers. Two-photon polymerization provides sub-micrometer resolution but is accompanied by a tradeoff of prolonged printing times. We propose combining single- and two-photon absorption to benefit from the dual capabilities, allowing for faster printing time while maintaining high resolution. In this study, we employ a continuous-wave blue light source to pre-sensitize a photocurable resin by single-photon absorption followed by a tightly focused femtosecond laser beam to provide the required energy reaching the polymerization threshold for solidifying the resin through two-photon absorption. We first investigate the impact of pre-sensitization by blue light illumination followed by irradiation with a focused femtosecond laser beam and find that the voxel growth dynamics are markedly altered. Specifically, pre-sensitization by blue light lowers the polymerization threshold power of the femtosecond laser beam and increases the speed of voxel growth. We then exploit this effect by building a custom two-photon 3D printer in which the blue light pre-sensitization is created in a light-sheet configuration. We report successfully printed 3D objects for which the average femtosecond laser power was reduced by 28.6 % and the exposure time was reduced by a factor of two compared with polymerization performed only with the femtosecond laser beam. Additionally, a 63 % improvement in axial voxel size is attained through blue light-sheet pre-sensitization. Our theoretical analysis based on a diffusion-free model suggests that the mechanism of the pre-sensitization is oxygen depletion followed by a single-photon background latent polymerization.

Blue light excitable fluorescent green security ink for anticounterfeit application

AbstractFluorescent security printing inks on flexible substrates is an arena that demands consistent developments to prevent the ever increasing menace of document/product counterfeiting. Visible light is a much more accessible and safer excitation source than the commonly used ultraviolet (UV) light. In this context, a simple Schiff base 4-pyridyl-benzylidene 2,4-difluoro aniline (PBDFA) is synthesized as a colorant with significant solid-state fluorescence for preparing security ink formulation. A huge challenge lies in preparing a security ink that does not fluoresce under UV light but produces a green fluorescence when irradiated with a blue light source. Such prints would be hard to forge as compared to the existing UV luminescent security inks. The screen prints obtained on a UV dull paper substrate using the solvent-based PBDFA ink revealed good blue light excitable green fluorescence, photostability, and colorimetric, densitometric, and rub resistance characteristics.

Preparation of Semiconducting Films By Electrooxidation of Naphthalene

Due to promising electronic and optical properties, conductive polymers are attracting significant interest. Conductive polymers find applications in electronic devices, e.g. substituted polynaphthalenes are used as blue light sources in OLEDs1. The ability to block the substitution sites where the subsequent polymer unit may be added by functional groups allows the polymer structure to be designed2. Moreover, one of the benefits of conductive polymers is the ability to modify the band gap of these materials by adding substituents to the main chain.Naphthalene, as the smallest polycyclic hydrocarbon, is an interesting precursor for synthesis semiconducting materials. The anodic oxidation of naphthalene has been described several times in the literature3,4, however, only formation of 1,4-polynaphthalene in the form of a granular product has been reported.In our research, we performed naphthalene electrooxidation and investigated the impact of the experimental conditions such as naphthalene concentration, water content, and electrode material on the obtained semiconducting materials. We used mass spectrometry to observe mass progression and determine molecular mass of the obtained polymers. The results of electron microscopy imaging showed fine quality coating. We studied the electronic properties of the polymers by cyclic voltammetry and impedance spectroscopy. Based on the results, we discussed the possible mechanism of the reaction. Samanta, S. K. et al. Synthesis of high molecular weight 1,4-polynaphthalene for solution-processed true color blue light emitting diode. Macromolecules 51, 8324–8329 (2018).Debad, J. F. & Bard, A. J. Electropolymerization of acenaphtho[1,2-k]fluoranthene derivatives: Formation of a new conductive electroactive electrochromic hydrocarbon ladder polymer. J Am Chem Soc 120, 2476–2477 (1998).Zecchin, S., Tomat, R., Schiavon, G. & Zotti, G. Polynaphthylene films from anodic coupling of naphthalene. Synthetic Metals vol. 25 (1988).Huang, Z., Qu, L., Shi, G., Chen, F. & Hong, X. Electrochemical polymerization of naphthalene in the electrolyte of boron trifluoride diethyl etherate containing trifluoroacetic acid and polyethylene glycol oligomer. Journal of Electroanalytical Chemistry 556, 159–165 (2003).

Modified Hybrid Hydroxyapatite-Silver Nanoparticles Activated via a Blue Light Source in Various Concentrations in Two-Step Self-Etch Adhesive to Caries-Affected Primary Dentin.

Aims: To evaluate hydroxyapatite-silver (HA-Ag) hybrid nanoparticles (NPs), as an antibacterial agent when integrated in self-etch (SE) adhesive. Blue light activated HA-Ag hybrid NP incorporation on mechanical properties, degree of conversion (DC), and microtensile bond strength (μTBS). Method: Eighty primary molar teeth have carious lesions reaching the dentin but not involving the pulp. The infected dentin was removed and carious-affected dentin (CAD) was preserved. Forty samples were inoculated with Streptococcus mutans. All primary teeth (n = 80) were allocated into four groups based on the incorporation of HA-Ag hybrid NPs in different concentrations (0%, 1%, 5%, and 10%). Group 1: 0% HA-Ag hybrid NPs + Clearfil SE bond primer, group 2: 1% HA-Ag hybrid NPs + Clearfil SE bond primer, group 3: 5 wt% HA-Ag NPs + Clearfil SE bond primer, and group 4: 10 wt% HA-Ag NPs + Clearfil SE bond primer. The survival rate assessment of S. mutans was conducted on 40 inoculated samples. On the remaining primary teeth (n = 40), Clearfil SE bonding agent was applied uniformly via a blue light source. The composite buildup was performed on the samples and μTBS and failure analysis assessed. Fourier transform infrared spectroscopy was performed to assess DC. Survival rates of S. mutans and μTBS among the tested groups were compared using ANOVA and Tukey post hoc analysis. Results: 10 wt % HA-Ag NPs + Clearfil SE bond primer exhibited the highest level of antibacterial efficacy (0.14 ± 0.02 CFU/mL) against S. mutans. The highest μTBS (18.38 ± 0.78 MPa) at the composite/CAD interface was in group 2 (1 wt % HA-Ag NPs + Clearfil SE bond primer + Clearfil SE bonding agent + activation with a blue light source). The highest DC was observed in the control group with Clearfil SE bond primer + Clearfil SE bonding agent + activation with a blue light source. Conclusion: 1 wt% HA-Ag hybrid NPs showed enhanced antibacterial effectiveness, DC, and bond strength of the SE adhesive to the primary CAD.

Diagnostic validity of ICDAS clinical criteria on digital 3D models

ObjectiveTo assess the diagnostic validity of ICDAS clinical criteria on 3D dental models from intraoral scanning. MethodsThis is a retrospective analysis on part of the baseline sample collected in a cohort study and included 73 participants (12–19 years) from Denmark and Greece. The assessment was made by visual inspection, and then by visual inspection associated with radiographs. All participants were scanned with TRIOS 4 which uses white light to obtain the 3D models with tooth color, as well as blue light source (415 nm) for fluorescence. The 3D models’ evaluation was conducted using tooth-color texture and subsequently fluorescence. Two scores were obtained for the 3D model examination: i) ICDAS based on tooth-color information; ii) ICDAS based on tooth-color information supplemented with fluorescence. For the analysis, weighted kappa, sensitivity (SE), specificity (SP) and accuracy (ACC) were calculated. ResultsRegarding all lesions the values for SE, SP, and ACC were respectively 0.804, 0.801, and 0.802 for tooth-color, and 0.819, 0.808, and 0.810 for tooth-color supplemented with fluorescence. In terms of accuracy parameters for moderate-extensive lesions, the values for SE, SP, and ACC for tooth color were 0.709, 0.948, and 0.944, while for fluorescence they were 0.815, 0.937, and 0.934. ConclusionCaries assessment with ICDAS criteria on 3D dental models produces reliable scores. Visual caries analysis using 3D models demonstrates commendable diagnostic accuracy and reasonable consistency with traditional methods. The use of intraoral scanners may be beneficial in evaluating occlusal caries. Clinical SignificanceThe importance of this study is to prove the diagnostic accuracy of caries lesions diagnosis made using and intraoral scanner and to offer greater confidence to professionals who use this diagnosis tool in their daily clinical practice. Intraoral scanners demonstrate to be an accurate tool for diagnosing occlusal caries.

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.

Multifunctional skin dressings synthesized via one‐pot photopolymerization: Advancing wound healing and infection prevention strategies

AbstractIn the field of wound healing treatment, the development of new materials is essential to cover multiple functions, such as acceleration of the healing process, prevention of infection and response to stimuli, especially if they present lower costs or are easier to manufacture. These properties are of great importance to prompt skin cicatrization. In this work, new multifunctional skin dressings for wound healing and infection prevention are developed based on new hydrogel materials. The dressings are produced via a straightforward and environmentally friendly one‐pot photopolymerization manufacturing process utilizing vitamin B2 aqueous solutions as sensitizer, and energy‐efficient blue light sources. These dressings exhibit a high swelling capacity, pH and temperature responsiveness, biocompatibility, antimicrobial activity in the absence of conventional antibiotics, and are capable of promoting wound healing. The formulation is based on the combination of three monomers: 2‐((methacryloyloxy)ethyl)trimethylammonium chloride, methacrylic acid and N‐vinyl caprolactam. Collagen, hyaluronic acid, and essential oil of hop are added to enhance antimicrobial properties and stimulate regenerative cellular processes. In vivo experiments have demonstrated that pristine dressings are superior in promoting collagen and fibroblast regeneration and accelerating cicatrization as compared to dressings containing natural products. The dressing embedded with hop also displayed antimicrobial characteristics. The preparation and testing of these new efficient wound dressings are described. This study is distinctive in its integration of environmentally conscious manufacturing techniques with innovative material formulations, resulting in superior wound dressings that are both cost‐effective and highly functional. By achieving enhanced healing and infection prevention without the employment of conventional antibiotics, this work represents a substantial advancement in sustainable and effective wound care management.

Are phlebotomine sand flies (Diptera: Psychodidae) really attracted to UV-light sources?

Phlebotomine sand flies are the sole confirmed vector of leishmaniosis, a group of endemic and re-emerging diseases in southern European countries such as Spain. Light traps are the major surveillance method currently being employed. Nevertheless, color light attraction by sand flies remains mostly unknown. Following prior research, the effect of UV-LED light sources, and its synergic effect with different color lights has been evaluated employing a modified Flebocollect (FC) light trap model. Results suggest that female Phlebotomus perniciosus sand flies are more attracted to a FC trap lured with the combination of blue and UV LED light sources than commercial CDC (Center for Disease Control and prevention) traps (Bonferroni post-hoc test; p < 0.08; blue/UV mean = 0.50; CDC mean = 0.13), while the combination of red and UV modified-traps excel in capturing Sergentomyia minuta sand flies (Bonferroni post-hoc test; p < 0.04; blue/UV mean = 1.19; CDC mean = 0.66). However, based on our prior studies, incorporating UV light sources into sand fly traps does not seem to enhance their attractiveness, as it has not resulted in higher capture rates. These findings contribute to understanding how sand flies’ vision and light color detection is. Further research is recommended to standardize trap construction procedures and explore variations in different endemic regions according to different sand fly species.

Structural colour in the brown algal genus Sporochnus (Sporochnales, Phaeophyceae)

ABSTRACT The colour produced by an object’s microstructure rather than by pigments is generally called structural colour. Various macroalgae have some mechanisms of structural colouration. The presence of structural colour in the brown algae is well known in the Dictyotales and Fucales but has recently been reported in the Sporochnales where Sporochnus dotyi has structures in the terminal assimilatory filaments (trichothallic hairs) that produce a pronounced green iridescence. Based on observations by light microscopy, the structural colour of this species was caused by iridescent bodies, 10–15 µm in diameter, within the cells of assimilatory filaments. In contrast, another Sporochnus species known as S. radiciformis in Japan (S. radiciformis auct. japon.) also contains iridescent bodies of 6–10 µm diameter in the assimilatory filaments, but no significant structural colour was observed. In epi-illumination observations using red, green and blue LED light sources, iridescent bodies of S. dotyi showed stronger reflection of green compared with red and blue, whereas the reflections were similar among those colours in S. radiciformis. Transmission electron microscopy (TEM) using a rapid freezing method revealed that homogeneous globules 130–160 nm in diameter were tightly packed inside the iridescent bodies of S. dotyi, whereas the sizes of the globules were markedly irregular in iridescent bodies of S. radiciformis. Therefore, we conclude that the structural colouration of S. dotyi is caused by the interference and diffraction of incident light caused by the crystal lattice-like structure of tightly packed and regularly arranged globules of homogeneous size in the iridescent bodies, which is similar to the mechanism causing iridescence in opal. A similar opal-like structure of iridescent bodies causing structural colouration was recently reported in Ericaria selaginoides, but that of S. dotyi lacked the dynamic shift of the globules shown in E. selaginoides that resulted in a change of the wavelength of reflected light.

Evaluation and activity of new porphyrin-peptide cage-type conjugates for the photoinactivation of Mycobacterium abscessus.

Mycobacterium abscessus is increasingly recognized as an emerging opportunistic pathogen causing severe lung diseases and cutaneous infections. However, treatment of M. abscessus infections remains particularly challenging, largely due to intrinsic resistance to a wide panel of antimicrobial agents. New therapeutic alternatives are urgently needed. Herein, we show that, upon limited irradiation with a blue-light source, newly developed porphyrin-peptide cage-type photosensitizers exert a strong bactericidal activity against smooth and rough variants of M. abscessus in planktonic cultures and in biofilms, at low concentrations. Atomic force microscopy unraveled important morphological alterations that include a wrinkled and irregular bacterial surface. The potential of these compounds for a photo-therapeutic use to treat M. abscessus skin infections requires further evaluations.IMPORTANCEMycobacterium abscessus causes persistent infections and is extremely difficult to eradicate. Despite intensive chemotherapy, treatment success rates remain very low. Thus, given the unsatisfactory performances of the current regimens, more effective therapeutic alternatives are needed. In this study, we evaluated the activity of newly described porphyrin-peptide cage-type conjugates in the context of photodynamic therapy. We show that upon light irradiation, these compounds were highly bactericidal against M. abscessus in vitro, thus qualifying these compounds for future studies dedicated to photo-therapeutic applications against M. abscessus skin infections.

Effect of different microalgae-bacterium-fungus symbiont technologies on nutrient removal from aquaculture wastewater and biogas upgrading under a variety of mixed light wavelengths

To develop and characterize novel microalgae-based technology under different mixed light-emitting diode (LED) light wavelengths for simultaneous treatment of actual aquaculture tailwater and biogas upgrading, the performance of four microalgal cultivations in bamboo shrimp aquaculture tailwater treatment and biogas upgrading were systematically examined and analyzed. The results demonstrated that Chlorella vulgaris (C. vulgaris)-endophytic bacterium (S395-2)-Clonostachys rosea (C. rosea) symbiont had the highest growth rate, daily production rate and carbonic anhydrase activity at the 7th d treatment time-point under Red(5): Blue(5) LED mixed light source. After 10d treatment, the nutrient removal efficiency of C. vulgaris-S395-2-C. rosea symbiont under Red(5): Blue(5) LED mixed wavelengths reached up to 93.7% for total inorganic nitrogen, 97.4% for ammonium nitrogen, 96.9% for nitrate nitrogen and 98.8% for phosphate; carbon dioxide (CO2) removal rate maintained at 53.1% without significantly affecting methane (CH4) level. In summary, the present study demonstrates that Red (5): Blue(5) LED mixed wavelengths optimally increase the performance of C. vulgaris-S395-2-C. rosea symbiont in nutrient and CO2 removal without loss of CH4, providing a framework for future simultaneous performing actual aquaculture tailwater treatment and biogas upgrading using microalgae-endophytic bacteria-fungus symbiont.

Chandra and HST studies of the X-ray sources in the globular cluster NGC 362

ABSTRACT We analyse a Chandra observation of the rich globular cluster NGC 362, finding 33 X-ray sources within 1 arcmin (1.2 half-mass radii) of the cluster centre. Spectral analysis of the brightest source (X1) shows blackbody-like emission, indicating it is likely a quiescent low-mass X-ray binary; we find a possible counterpart that falls in the sub-subgiant region. We use Hubble Space Telescope ultraviolet (UV) Globular Cluster Survey photometry to identify 15 potential optical/UV counterparts to these X-ray sources, including two background active galactic nuclei. We identify no likely cataclysmic variables (CVs), probably due to crowding in optical filters in the core, though we predict of order 8 CVs among the detected X-ray sources. We identify three other sub-subgiants and two red straggler counterparts, which are likely powered by coronal activity, along with five other potential coronally active binary counterparts to three X-ray sources. Finally, we note two unusual counterpart candidates that lie to the red of the red giant branch in V606 − I814, and shift well to the blue of the red giant branch in ultraviolet colour–magnitude diagrams. These systems seem to contain a red giant with a distorted evolutionary history, plus a bright blue light source, either a blue straggler star (an Algol-like system) or an accreting white dwarf (a long-period CV, or a symbiotic star).

Modification of a desktop FFF printer via NIR laser addition for upconversion 3D printing

Traditional photopolymer-based 3D printing methods require sequential printing of thin layers, due to short penetration depths of UV or blue light sources used by these techniques. In contrast, upconversion 3D printing circumvents the layer-by-layer limitation by taking advantage of upconversion luminescence processes and the high penetration depths offered by near-infrared (NIR) lasers, allowing for selective crosslinking of voxels at any depth or position within the resin container. The implementation of this technique required the construction of a 3D printer with the ability of focusing the laser on any point of the space. For this, a low-cost fused filament fabrication (FFF) printer was modified by incorporating a 980 nm laser and laser control circuit. The total cost of the parts required for modification was £180. With enhanced penetration depths up to 5.8 cm, this method also allows for printing inside or through existing 3D printed parts. This opens doors for restoration of broken items, in situ bioprinting, 3D-circuitry, and notably, 3D printing inside cavities of a different material, illustrating numerous opportunities for practical applications.

Endoscopic 5-Aminolevulinic Acid–Induced Fluorescence-Guided Intraparenchymal Brain Tumor Resection—Can the Endoscope Detect More Fluorescence Than the Microscope?

ObjectivesUsing a laboratory-based optical setup we show that 5ALA fluorescence is better detected using the endoscope than the microscope. Furthermore, we present our case series of fully-endoscopic 5ALA guided resection of intraparenchymal tumors. MethodsA Zeiss Pentero® microscope was compared to the Karl Storz Hopkins® endoscope. The spectra and intensity of each blue light source were measured. Quantitative fluorescence detection thresholds were measured using a spectrometer. Subjective fluorescence detection thresholds were measured by 6 blinded neuro-oncology surgeons. Clinical data were prospectively collected for all consecutive cases of fully-endoscopic 5ALA guided resection of intraparenchymal tumors between 2012-2023. ResultsThe intensity of blue light on the sample was greater for the endoscope than the microscope at working distances below 20mm. The quantitative fluorescence detection thresholds were lower for the endoscope than the microscope at both 30/10mm working distances. Fluorescence detection threshold was 0.65-0.80% relative DCM concentration (3.20x10-7 to 3.94x10-7mol/dm-3) for the microscope, 0.40-0.55 % relative concentrations (1.97x10-7 to 2.71x10-7mol/dm-3) for the endoscope at 30mm and 0.15-0.30% relative concentrations (7.40x10-8 to 1.48x10-7mol/dm-3) for the endoscope at 10mm.49 5ALA endoscope-assisted brain tumor resections were carried out on 45 patients (mean age=41, male=28). Greater than 95% resection was achieved in 80% of cases and gross total resection (GTR) in 42%. GTR was achieved in 100% of tumors in non-eloquent locations. There was 1 new neurological deficit. ConclusionThe endoscope provides enhanced visualization/detection of 5ALA-induced fluorescence compared to the microscope. 5ALA endoscopic-assisted resection of intraparenchymal tumors is safe and feasible.

Relationship of SSVEP response between flash frequency conditions.

This study delves into the application of Brain-Computer Interfaces (BCIs), focusing on exploiting Steady-State Visual Evoked Potentials (SSVEPs) as communication tools for individuals facing mobility impairments. SSVEP-BCI systems can swiftly transmit substantial volumes of information, rendering them suitable for diverse applications. However, the efficacy of SSVEP responses can be influenced by variables such as the frequency and color of visual stimuli. Through experiments involving participants equipped with electrodes on the brain's visual cortex, visual stimuli were administered at 4, 17, 25, and 40Hz, using white, red, yellow, green, and blue light sources. The results reveal that white and green stimuli evoke higher SSVEP responses at lower frequencies, with color's impact diminishing at higher frequencies. At low light intensity (1W), white and green stimuli elicit significantly higher SSVEP responses, while at high intensity (3W), responses across colors tend to equalize. Notably, due to seizure risks, red and blue lights should be used cautiously, with white and green lights preferred for SSVEP-BCI systems. This underscores the critical consideration of color and frequency in the design of effective and safe SSVEP-BCI systems, necessitating further research to optimize designs for clinical applications.

Synthesis and luminescent properties of a new cyan Ca18Li6-3xYx(PO4)14:0.1Eu phosphors and PVA-based composite films for multifunctional applications

The development of light-emitting materials capable of efficiently emitting broad-band cyan light is of paramount importance in the quest for full-spectrum white light illumination. In this study, a series of new Ca18Li6-3xYx(PO4)14:0.1Eu phosphors with adjustable luminescent properties were synthesized through a high-temperature solid-phase method, and the investigation encompassed an analysis of their crystal structures, luminescence characteristics, and thermal stability. Meanwhile, the optimal doping concentration of Y3+ ions in the Ca18Li6-3xYx(PO4)14:0.1Eu host was identified to be x = 0.3, achieved through the modulation of the substitution ratio of Y3+ to Ca2+ to regulate the occupancy of Eu2+ at different sites. The resulted in the generation of asymmetric cyan color emission spectra (FWHM = 47 nm) with broad-band emission spanning the 425–550 nm range under 378 nm excitation. In addition, the application of the optimized cyan-emitting phosphor Ca18Li5.1Y0.3(PO4)14:0.1Eu in w-LED devices led to a significant enhancement in the CRI from 89.1 to 91.2, accompanied by a reduction in the correlated color temperature from 4896 K to 4566 K. These results highlight the potential utility of the cyan-emitting Ca18Li5.1Y0.3(PO4)14:0.1Eu phosphors in full-visible-spectrum solid-state illumination. Notably, the optimized cyan-emitting phosphor Ca18Li5.1Y0.3(PO4)14:0.1Eu was synthesized in conjunction with soluble polyvinyl alcohol (PVA) to yield a transparent anti-counterfeiting ink. The resulting film exhibited exceptional flexibility, foldability, and superior thermal and optical properties. Moreover, the emission band of this phosphor, situated in the 425 nm–550 nm spectral region, represents a crucial blue light source beneficial for plant growth. In summary, the highly efficient phosphor Ca18Li5.1Y0.3(PO4)14:0.1Eu is a promising material with multifunctional luminescent potential for general illumination, anti-counterfeiting, and light-converting agricultural films.