Maximum Light Research Articles

Stuck in the Dark: No Association between Light, Sound, and Delirium in the PICU

AbstractThe purpose of this study was to evaluate the association between sound and light variables and development of delirium in pediatric intensive care unit (PICU) patients within the subsequent 3 days. Light and sound were continuously measured, and patient-specific data were collected daily. Outcomes included presence of delirium, determined by Cornell Assessment of Pediatric Delirium (CAPD) score ≥ 9 on at least 1 day, and development of delirium in the subsequent 3 days. One hundred and forty-two patients were enrolled, totaling 896 study days. Delirium prevalence was 31%. Neurologic diagnosis, younger age, longer PICU stay, restraints, benzodiazepines, opiate infusion, and dexmedetomidine were associated with delirium. Nighttime sound peaks (>70 and >80 dB) were not associated with delirium (p = 0.94 and 0.36, respectively). Light intensity during midday hours (12:00, 1:00, 2:00 pm) was not associated with the development of delirium (p=0.93, 0.81, 0.83, respectively), nor was maximum light at night, difference between maximum daytime and nighttime light, or between maximum and minimum daytime light (p = 0.15, 0.46, and 0.96, respectively). When adjusting for covariables, none of the sound or light variables was associated with delirium. Despite increasing awareness of pediatric delirium, data surrounding modifiable risk factors and concrete treatment strategies are lacking. We found no significant association between light or sound and development of delirium in PICU patients. However, there was little difference between daytime and nighttime light and sound, which may have impacted findings. As the etiology of delirium is multifactorial and potentially different for individual patients, targeted light/dark cycles warrant further study as they relate to delirium and critical illness.

SN 2017fzw: A Fast-Expanding Type Ia Supernova with Transitional Features

In this study, we analyzed the optical observations of a subluminous Type Ia supernova (SN Ia) 2017fzw, which exhibited high photospheric velocity (HV) at B-band maximum light. The absolute B-band peak magnitude was determined to be MmaxB=−18.65±0.13 mag, similar to 91bg-like SNe Ia. An estimation of the rate of decline for the B-band light curve was determined to be Δm15(B)=1.60±0.06 mag. The spectra of SN 2017fzw were similar to those of 91bg-like SNe Ia, with prominent Ti ii and Si ii λ5972 features at early phases, gradually transitioning to spectra resembling normal (mainly HV subclass) SNe Ia at later phases, with a stronger Ca ii NIR feature. Notably, throughout all phases of observation, SN 2017fzw displayed spectral evolution characteristics that were comparable to those of HV SNe Ia, and at peak brightness, the Si ii λ6355 velocity was determined to be 13,800 ± 415 km s−1 and a more pronounced Ca ii NIR feature was also detected. Based on these findings, we classify SN 2017fzw as a transitional object with properties of both normal and 91bg-like SNe Ia, providing support for the hypothesis of a continuous distribution of supernovae between these two groups.

Metasurface-Based Solar Absorption Prediction System Using Artificial Intelligence

Solar energy is a significant, environment-friendly source of renewable energy. The solar absorber transforms solar radiation into heat energy as an effective green energy source. Therefore, increasing its absorbing capacity can improve a solar absorber’s effectiveness. This paper proposes a tungsten tantalum alloy with silicon dioxide (WTa-SiO2) ceramic layer-based solar absorber system with two different metasurfaces to enhance absorptivity and boost the solar absorber efficacy. The absorbance is also improved by adjusting the resonator thickness and material thickness, and the maximum visible light absorption is achieved by the suggested solar filter design. Moreover, Golden Eagle Optimization (GE)-based deep AlexNet algorithm is proposed for predicting the parameter variation and their effect on absorbance. The optimization technique is used to increase the effectiveness of the solar absorber by optimizing the design parameters. The features from the WTa-SiO2 design are extracted by the proposed Principal Component-Autoencoder (PC-AE) method. Experimental results show that the proposed system can effectively predict absorptivity with a reduced computational time. The proposed method demonstrates superior prediction performance with an absorption prediction efficiency of 99.8% compared to the existing methods. Thus, the proposed WTa-SiO2 metasurface-based solar absorber can be used for photovoltaic applications.

Response Characteristics of Photosynthetic Productivity to the Canopy Spatial Distribution Pattern of Larix kaempferi

The spatial distribution of the forest canopy plays an important role in the transpiration and photosynthetic capacity of trees, ultimately affecting their growth and biomass production. Despite its importance, how canopy photosynthetic productivity enhancement depends on canopy spatial distribution remains unclear. To address this knowledge gap, we conducted a study on Larix kaempferi (Lamb.) Carrière (L. kaempferi) plantations in Gansu, China, investigating the relationship between canopy height, leaf area, seasonal variations in canopy spatial distribution, and photosynthetic parameters. The results showed that the net photosynthetic rate, stomatal conductance, and transpiration rate of L. kaempferi increase with greater canopy height, while photosynthetically active radiation shows the opposite trend. Canopy photosynthetic productivity peaked in April, May, and June when the height in the canopy was 40%, followed by 20%, and then 30% from the perspective of spatiotemporal canopy spatial distribution. Maximum leaf area (10.7 m2) and photosynthesis productivity (919.6 mg·C·h−1) were observed when the height in the canopy ranged from 48%–59%. The changes increased sunlight exposure (75%–88%, 88%–100%) in different canopy areas. Additionally, there was a decrease in the amount of space covered by shade (25%–38%, 50%–63%, and 63%–75%), depending on the specific region within the canopy. By scientifically managing stand density, the canopy spatial distribution can be optimized for photosynthesis, resulting in maximum light interception rates, enhanced photosynthetic capacity, and reduced “non-functional canopy”. These findings offer effective and scientifically informed management strategies for the forestry industry. By optimizing the structure of the canopy, specifically in L. kaempferi, these strategies aim to maximize photosynthetic productivity.

SN 2016ije: An SN 2002es-like Type Ia Supernova Exploded in a Metal-poor and Low-surface Brightness Galaxy

We have conducted photometric and spectroscopic observations of the peculiar Type Ia supernova (SN Ia) 2016ije that was discovered through the Tsinghua-NAOC Transient Survey. This peculiar object exploded in the outskirts of a metal-poor, low-surface brightness galaxy (i.e., M g = −14.5 mag). Our photometric analysis reveals that SN 2016ije is subluminous ( = −17.65 ± 0.06 mag) but exhibits relatively broad light curves (Δm 15(B) = 1.35 ± 0.14 mag), similar to the behavior of SN 2002es. Our analysis of the bolometric light curve indicates that only 0.14 ± 0.04 M ⊙ of 56Ni was synthesized in the explosion of SN 2016ije, which suggests a less energetic thermonuclear explosion when compared to normal SNe Ia, and this left a considerable amount of unburned materials in the ejecta. Spectroscopically, SN 2016ije resembles other SN 2002es-like SNe Ia, except that the ejecta velocity inferred from its carbon absorption line (∼4500 km s−1) is much lower than that from silicon lines (∼8300 km s−1) at around the maximum light. Additionally, most of the absorption lines are broader than other 02es-like SNe Ia. These peculiarities suggest the presence of significant unburned carbon in the inner region and a wide line-forming region along the line of sight. These characteristics suggest that SN 2016ije might originate from the violent merger of a white dwarf binary system, when viewed near an orientation along the iron-group-element cavity caused by the companion star.

Drivers of nocturnal interactions between ground-level ozone and nitrogen dioxide

<p>This study analyses nighttime (7 p.m. to 6 a.m.) light pollution effects on ground-level ozone production in urban and sub-urban sites in Malaysia. In the absence of solar radiation, no photochemical reaction will occur during nighttime, resulting in zero readings of ground-level ozone (O3). O3 and nitrogen dioxide (NO2) data collected in 2020 were analysed to assess time series and diurnal variability at each site and between sites. The highest nighttime mean O3 concentration is Minden (60 ppb); meanwhile, for nighttime mean NO2 concentrations, the highest is Klang (43 ppb). The results show that sub-urban experienced higher O3 variations compared to urban areas. The monthly mean nighttime O3 and NO2 in urban and suburban areas display a gradual increase in O3 and NO2 variations from March to April, followed by a decreasing trend in the mid of the year. These variations in monthly air pollutants are related to the MCO, CMCO, and RMCO in Malaysia during 2020. Putrajaya (sub-urban site) was the darkest site (average lux: 20) for the whole dataset. In contrast, Minden (sub-urban site) was recorded as the brightest site with maximum light pollution (average lux: 70). The relationship between O3 and NO2 shows a negative correlation during nighttime for urban and suburban sites. Light pollution can reach levels that might affect nocturnal O3 and NO2 concentrations; therefore, the long-term variability of light pollution is essential for air pollution studies.</p>

Impact of Snowmelt Conditions on the Isotopic Composition of the Surface Waters of the Upper Ob River during the Flood Period

For many of the Siberian rivers, and the Upper Ob in particular, 70–80% of the volume of the annual water runoff is formed during the spring flood. Thus, factors influencing the formation of water runoff during the spring flood are paramount. We explain changes in the isotopic composition of the Upper Ob surface waters by changing different components’ contribution to the runoff water discharge over the spring flood period. We suggest estimating the time of meltwater flow from the Upper Ob watershed to the outlet section using the difference between the date of the complete melting of the snow cover in the catchment area and the date of the maximum light isotope composition of water in the outlet section. We show that a sharp short-term weighting of the isotopic composition of water in the river at the end of the first phase of the flood may be associated with the influx of autumn soil moisture, displaced from the soils by snowmelt waters.

A graph-based spectral classification of Type II supernovae

Given the ever-increasing number of time-domain astronomical surveys, employing robust, interpretative, and automated data-driven classification schemes is pivotal. Based on graph theory, we present new data-driven classification heuristics for spectral data. A spectral classification scheme of Type II supernovae (SNe II) is proposed based on the phase relative to the maximum light in the V band and the end of the plateau phase. We utilize a compiled optical data set that comprises 145 SNe and 1595 optical spectra in 4000–9000 Å. Our classification method naturally identifies outliers and arranges the different SNe in terms of their major spectral features. We compare our approach to the off-the-shelf umap manifold learning and show that both strategies are consistent with a continuous variation of spectral types rather than discrete families. The automated classification naturally reflects the fast evolution of Type II SNe around the maximum light while showcasing their homogeneity close to the end of the plateau phase. The scheme we develop could be more widely applicable to unsupervised time series classification or characterization of other functional data.

Optical Properties and Photocatalytic Performance of Si/TiO2 Tandem Semiconductor Microwire Slurries

Semiconductor particle suspension reactors hold promise as a possible low-cost strategy for solar water-splitting, but they face several challenges that have inhibited their solar-to-hydrogen (STH) efficiencies. A tandem microparticle with a buried junction addresses some of these challenges and offers a pathway to high STH efficiency. As a slurry, the tandem microparticles need to be suspended and well dispersed with maximum light absorption for a minimal photoactive particle concentration. Herein, proof-of-concept Ni/np+-Si/FTO/TiO2 tandem microwire structures capable of unassisted solar water-splitting were investigated as a slurry using uplifting N2 carrier gas bubbles. Transmittance, reflectance, and absorptance of the slurry were characterized as a function of wavelength, bubble flowrate, and tandem microwire concentration using an integrating sphere. Notably, a slurry absorptance of 70–85% was achieved with only 1% of the solution volume filled with a photoactive material. Photochemical activity of the slurry was characterized with in situ monitoring of the photodegradation of methylene blue, including the effects of particle concentration, bubble flowrate, spectral mismatch, intermixed light scattering particles, and a back reflector.

Spectra of pathogens predict lethality of blue light photo-inactivation

Whole-cell spectra of human pathogens are examined to identify species-specific wavelengths of maximum light absorption. It is presented how these data relate to clinical efficacy for antimicrobial phototherapies. Twelve species of microorganisms were cultured to exponential growth then processed and suspended in a scattering solution. Diffuse reflectance from the sample was delivered to two spectrometers that covered a spectral range of 370nm to 1200nm. Reflectance spectra were converted to relative absorbance. Absorbance spectra from multiple trials were averaged to produce a representative spectrum for each species. All pathogens studied demonstrated an absorbance spectrum with a primary component in the range 405-426 nm and 1-4 secondary components in the range 445-636 nm. Antibiotic-resistant and antibiotic-sensitive strains of Pseudomonas aeruginosa (Pa) had identical absorbance spectra. Whole-cell spectra support the hypothesis that a pathogen’s absorbance is directly related to efficacy of photoinactivation. The spectral signatures in all pigmented bacteria tested appear to be that of various combinations of in situ porphyrins. The knowledge of the absorption spectrum of a given pathogen provides a logical start for selecting the appropriate light source for a clinical trial.

Mass Cultivation of Microalgae: II. A Large Species Pulsing Blue Light Concept.

If mass cultivation of photoautotrophic microalgae is to gain momentum and find its place in the new "green future", exceptional optimizations to reduce production costs must be implemented. Issues related to illumination should therefore constitute the main focus, since it is the availability of photons in time and space that drives synthesis of biomass. Further, artificial illumination (e.g., LEDs) is needed to transport enough photons into dense algae cultures contained in large photobioreactors. In the present research project, we employed short-term O2 production and 7-day batch cultivation experiments to evaluate the potential to reduce illumination light energy by applying blue flashing light to cultures of large and small diatoms. Our results show that large diatom cells allow more light penetration for growth compared to smaller cells. PAR (400-700 nm) scans yielded twice as much biovolume-specific absorbance for small biovolume (avg. 7070 μm3) than for large biovolume (avg. 18,703 μm3) cells. The dry weight (DW) to biovolume ratio was 17% lower for large than small cells, resulting in a DW specific absorbance that was 1.75 times higher for small cells compared to large cells. Blue 100 Hz square flashing light yielded the same biovolume production as blue linear light in both the O2 production and batch experiments at the same maximum light intensities. We therefore suggest that, in the future, more focus should be placed on researching optical issues in photobioreactors, and that cell size and flashing blue light should be central in this.

The Behavior of Bp Si Stars in the Far UV—Paper V: HD 92664

The analysis of spectra of the B8 Si-rich HD 92664 recorded by the SWP camera on board the International Ultraviolet Explorer reveals variations of the far-ultraviolet spectral energy distribution shortwards of 1700 Å over a time interval of about 2 months. In contrast, the mid-UV flux does not vary which suggests that changes of the silicon continuous and line opacity are the cause of the variations. The iron-peak elements, chromium, manganese and iron play a lesser role than silicon in these variations. Phased on previous ephemeris, the FUV minimum occurs at the rotational phase, ϕ = 0.0, which corresponds to maximum light in the V-band and minimum longitudinal magnetic field.

Analysis of Light Penetration Depth in Apple Tissues by Depth-Resolved Spatial-Frequency Domain Imaging.

Spatial-frequency domain imaging (SFDI) has been developed as an emerging modality for detecting early-stage bruises of fruits, such as apples, due to its unique advantage of a depth-resolved imaging feature. This paper presents theoretical and experimental analyses to determine the light penetration depth in apple tissues under spatially modulated illumination. Simulation and practical experiments were then carried out to explore the maximum light penetration depths in 'Golden Delicious' apples. Then, apple experiments for early-stage bruise detection using the estimated reduced scattering coefficient mapping were conducted to validate the results of light penetration depths. The results showed that the simulations produced comparable or a little larger light penetration depth in apple tissues (~2.2 mm) than the practical experiment (~1.8 mm or ~2.3 mm). Apple peel further decreased the light penetration depth due to the high absorption properties of pigment contents. Apple bruises located beneath the surface peel with the depth of about 0-1.2 mm could be effectively detected by the SFDI technique. This study, to our knowledge, made the first effort to investigate the light penetration depth in apple tissues by SFDI, which would provide useful information for enhanced detection of early-stage apple bruising by selecting the appropriate spatial frequency.

Comparison study of iron and iron-oxide nanoparticles for thermoplasmonic applications

The plasmonic nanoparticles have the properties of surface plasmon resonance (SPR) that can be used to heat up the surrounding by absorbing maximum light from an irradiated beam. Therefore, the present study reveals the photothermal effect of iron and iron-oxide nanosphere in different ambient environments with varying radii from 20 nm to 60 nm. Based on Mie’s theory, PyMieLab_V1.0 software is used to calculate the size-dependent absorption cross-section of spherical nanoparticles. The absorption spectra at λmax have been tuned from the UV to Infrared region of Fe nanoparticles in different surrounding environments while for Fe2O3 NPs, it reveals in the UV region. As the nanoparticle size increases, the absorption peak position of Fe and Fe2O3 NPs shifts towards the longer wavelength regime on the electromagnetic spectrum. It has been observed that the heat generation rate and the maximum temperature gradually increase with particle sizes and a 60 nm particle’s size has maximum heat generated as well as a maximum temperature increase further, iron NPs are more dominant than iron oxide NPs. At the resonance wavelength, the near-field enhancement is observed with the nanosphere's radii, but with variation in the value of refractive indices, it decreases. Thus, this simulated work opens potential applications in a newly emerging field like thermo-plasmonic and thermo-optic.

Cost-effective way of improving the optical properties of phosphor-in-glass by adjusting the particle size of glass powder

The effects of silicate glass particle size and Y3Al5O12: Ce3+ (YAG: Ce3+) phosphor doping concentration on the optical properties of phosphor-in-glass (PiG) samples were investigated. When the average particle size of glass powder was 160, 100, 60, and 30 μm, the transmittance of silicate glass with a thickness of 0.6 mm was 68%, 78%, 62%, and 54%, respectively. With the mixing of 4 wt% YAG: Ce3+ phosphor in each component of silicate glass, the transmitted luminous flux of PiG gradually increased with the increase of transmittance, reaching a maximum of 179.5 lm. Simultaneously, we found that with the increase in transmittance, the photoluminescence (PL) intensity of PiG gradually decreased; however, the total luminous flux of PiG has independent of transmittance. When the doping concentration of YAG: Ce3+ phosphor was 4 wt%, PiG achieved a maximum efficient white light emission of 212.61 lm/W under blue laser excitation at 2.31 W. All results indicate the outstanding feasibility of the prepared YAG-PiG in high-power/high-brightness white light-emitting diodes (WLEDs).

Effects of Light Intensity on in Vitro Regeneration Of Stevia Rebaudiana Bertoni, Bacopa Monnieri L. And Solanum Tuberosum L.

Light is the most essential factor controlling plant growth, morphogenesis, metabolism and chlorophyll content of plant cells, tissues and organ culture. The present investigations were carried out to find out effects of different light intensities (210, 500, 1000, 1500, 2000, 2500 and 3000 lx) on the regeneration of three plants, namely Stevia rebaudiana Bertoni., Solanum tuberosum L. and Bacopa monnieri L. Results showed that light intensity has a direct effect on plant growth in vitro. There was less time for shoot initiation and the highest mean number of shoots/explants (9.75 ± 3.862) of S. rebaudiana was observed from the nodal explants when the culture was maintained at 1000 lx light conditions. At maximum light intensity (3000 lx) best result was recorded for S. tuberosum. A distinct intensity of light, 1500 lx showed the best outcome both for the number and length of shoots of B. monnieri (p = 0.00). The present study also demonstrated the relationship between root growth and light condition. Bangladesh J. Bot. 52(1): 53-60, 2023 (March)

Light absorption enhancement of silicon solar cell based on horizontal nanowire arrays

The effects of geometry and horizontal positioning of ultrathin triangular silicon nanowires (SiNWs) on the function of solar cells (SCs) have been investigated. Two differentiated methods have been presented to improve the current density of SiNW-SCs. First, a semiperiodic array is used for better utilization of the optical antenna effect. In the second method, several NWs with different geometries are used to achieve broadband absorption. The key to increase absorption is irregularity. Therefore, maximum light absorption is achieved by introducing irregular NWs. A set of optimized irregular NWs have better properties compared to other broadband structures. Using irregular NW arrays, the increase in the absorption of SCs can be improved without applying more absorbent materials. Optimization processes are used to obtain the maximum current density of SCs.

Cross-fertilized biomimetic structures achieved through nanosphere lithography on an ultrathin wafer for flexible black c-Si SHJ solar cells

The millions of years of history of evolution are practically a history of optimization of all the biological designs and structures so as to cope up with nature and to get the best out of it. These natural designs can be exhaustive sources of readily available solutions for engineering and technological problems. Moth eye-like nanostructured anti-reflection coatings are an innovative concept for the fabrication of advanced and efficient solar cells due to its low reflection attributes when applied on the top of a cell. However, owing to its high surface area and low aspect ratio, the minority carrier life time and wide-angle light collection may be compromised, and these are treated as the major barriers of using such moth eye-like nanostructured anti-reflection coatingsin real cases. To overcome this problem, in this work, it has been aimed to introduce a ‘cross fertilized’ biomimetic structure between the ‘moth eye’ and ‘cacti’, so that maximum light can be utilized without much compromising the electrical properties. Detailed experimental and theoretical analyses on the optical and structural properties of such cross-fertilized nanostructures were carried out, giving emphasis on some crucial parameters like wide angle light collection, unified photon-electron harvesting capabilities, and surface recombination velocity. Finally, practical implementation of this optimized geometry has been carried out by the formation of ‘nano-cone’-based black c-Si structures through a metal-assisted chemical etching technique, followed by the fabrication of black p-c-Si/n-a-Si:H flexible solar cells.

Enhanced biohydrogen yield and light conversion efficiency during photo-fermentation using immobilized photo-catalytic nano-particles

Bacterial immobilization is a common method in anaerobic fermentation, since of the maintenance of high bacterial activity, insurance of high density microbial during continuous fermentation, and quick adaptability to the environment. While, the bio-hydrogen production capacity of immobilized photosynthetic bacteria (I-PSB) is seriously affected by the low light transfer efficiency. Hence, in this study, photo-catalytic nano-particles (PNPs) was added into the photo-fermentative bio-hydrogen production (PFHP) system, and its enhancement effects of bio-hydrogen production performance were investigated. Results showed that the maximum cumulative hydrogen yield (CHY) of I-PSB with 100 mg/L nano-SnO2 (154.33 ± 7.33 mL) addition was 18.54% and 33.06% higher than those of I-PSB without nano-SnO2 addition and control group (free cells), and the lag time was the shortest indicating a shorter cell arrest time, more cells and faster response. Maximum energy recovery efficiency and light conversion efficiency were also found to be increased by 18.5% and 12.4%, respectively.

Through-hole composite membrane with an ultrathin oxide shell for highly robust and transparent air filters

Exploring pore structures that are optically transparent and have high filtration efficiency for ultrafine dust is very important for realizing passive window filters for indoor air purification. Herein, a polyester track-etched (PETE) membrane with vertically perforated micropores is investigated as a cost-effective candidate for transparent window filters. The pore size, which governs transparency and filtration efficiency, can be precisely tuned by conformally depositing an ultrathin oxide layer on the PETE membrane via atomic layer deposition. The maximum visible light transmittance (∼81.2 %) was achieved with an alumina layer of approximately 55 nm, and the resulting composite membrane exhibited competitive filtration efficiency compared to commercial products. The chemically inert alumina layer also increased resistance to various external stimuli and enabled simple cleaning of the contaminated membrane surface with a solvent. The membrane installed on an insect screen effectively maintained its filtration performance (∼85 % for PM2.5) even after 10 reuse cycles under extremely harsh conditions (PM2.5 concentration: ∼5000 μg cm−3). The proposed through-hole composite membrane can expand the choice of aesthetic window filters to situations that require high outside visibility and daylighting.