Light Energy Density Research Articles

Effect of annealing temperature on the optoelectrical synapse behaviors of A-ZnO microtube

Optoelectronic synapses with fast response, low power consumption, and memory function hold great potential in the future of artificial intelligence technologies. Herein, a strategy of annealing in oxygen ambient at different temperatures is presented to improve the optoelectronic synaptic behaviors of acceptor-rich ZnO (A-ZnO) microtubes. The basic synaptic functions of as-grown and annealed A-ZnO microtubes including excitatory postsynaptic current (EPSC), short-term memory (STM) to long-term memory (LTM) conversion, and paired-pulse facilitation (PPF), were successfully emulated. The results show that the annealing temperature of 600 °C yields high figures of merit compared to other annealed A-ZnO microtubes. The 4-fold and 20-fold enhancement dependent on the light pulse duration time and energy density have been achieved in the 600 °C annealed A-ZnO microtube, respectively. Furthermore, the device exhibited a PPF index of up to 238% and achieved four cycles of “learning-forgetting” process, proving its capability for optical information storage. The free exciton (FX) and donor–acceptor pair (DAP) concentrations significantly influenced the persistent photoconductivity (PPC) behavior of A-ZnO microtubes. Therefore, the LTM response can be controlled by the adjustment of numbers, powers, and interval time of the optical stimulation. This work outlines a strategy to improve the EPSC response through defect control, representing a step towards applications in the field of optoelectronic synaptic device.

The Comparison between Energy Density of Blue and Red Light which Activation Silver Nanoparticles to Inhibition Candida albicans Biofilms

The Comparison between Energy Density of Blue and Red Light which Activation Silver Nanoparticles to Inhibition Candida albicans Biofilms

Protein sensing using deep subwavelength-engineered photonic crystals.

We demonstrate a higher sensitivity detection of proteins in a photonic crystal platform by including a deep subwavelength feature in the unit cell that locally increases the energy density of light. Through both simulations and experiments, the sensing capability of a deep subwavelength-engineered silicon antislot photonic crystal nanobeam (PhCNB) cavity is compared to that of a traditional PhCNB cavity. The redistribution and local enhancement of the energy density by the 50 nm antislot enable stronger light-molecule interaction at the surface of the antislot and lead to a larger resonance shift upon protein binding. This surface-based energy enhancement is confirmed by experiments demonstrating a nearly 50% larger resonance shift upon attachment of streptavidin molecules to biotin-functionalized antislot PhCNB cavities.

The successful application of light to the system of simultaneous nitrification/endogenous denitrification and phosphorus removal: Promotion of partial nitrification and glycogen accumulation metabolism

Partial nitrification (PN) and high glycogen accumulating metabolism (GAM) activity are the basis for efficient nitrogen (N) and phosphorus (P) removal in simultaneous nitrification endogenous denitrification and phosphorus removal (SNDPR) systems. However, achieving these processes in practical operations is challenging. This study proposes that light irradiation is a novel strategy to enhance the nutrient removal performance of the SNDPR system with low carbon to nitrogen ratios (C/N of 3.3–4.1) domestic wastewater. Light energy densities (Es) of 55–135 J/g VSS were found to promote the activity of ammonia-oxidizing bacteria (AOB) and GAM, while inhibiting the activity of nitrite-oxidizing bacteria (NOB) and polyphosphate accumulating metabolism (PAM). Long-term exposure to different light patterns at Es of 55–135 J/g VSS revealed that continuous light rapidly achieved PN by inhibiting NOB activity and promoted the growth of glycogen accumulating organisms (GAOs), allowing the removal of above 82 % N and below 80 % P. Intermittent light maintained stable PN by inhibiting the activity and growth of NOB and promoted the growth of polyphosphate accumulating organisms (PAOs) with high GAM activity (Accmulibacer IIC-ii and IIC-iii), allowing the removal of above 82 % N and 95 % P. Flow cytometry and enzyme activity assays showed that light promoted GAM-related enzyme activity and the metabolic activity of partial Accmulibacer II over other endogenous denitrifying bacteria, while inhibiting NOB translation activity. These findings provide a new approach for enhancing nutrient removal, especially for achieving PN and promoting GAM activity, in SNDPR systems treating low C/N ratio domestic wastewater using light irradiation.

Highly sensitive, modification-free, and dynamic real-time stereo-optical immuno-sensor

Modification-free biosensing with high specificity and sensitivity is essential for miniaturized, online, integrated, and rapid, or even real-time molecular analyses. However, most optical biosensors are based on surface pre-modification or fluorescent labeling, and have either low sensitivity or low quality factor (Q). To address these difficulties, in this study, an optical sensor prototype was developed with a microbubble optofluidic channel integrated inside a Fabry–Pérot cavity to three-dimensionally tailor the intra-cavity light field via the intra-cavity lensing (microbubble) configuration. A high Q-factor (∼105), small mode volume, and high light energy density were experimentally achieved with this “stereo-sensor” while maintaining an ultrahigh refractive index (RI) sensitivity (679 nm/RIU) and ultra-small RI resolution (∼10−7 RIU at 950 nm). Moreover, specific detection of very low concentration of biomolecules (5 fg/mL for human IgG and 0.5 pg/mL for human serum albumin (HSA)) and wide range of protein concentrations (e.g., fg/mL–ng/mL for human IgG and pg/mL–ng/mL for HSA) without probe pre-modification were achieved owing to the RI change specifically associated with the probe–target binding and the corresponding bio-macromolecular conformation change. This modification-free stereosensing scenario is applicable to continuous, real-time, and multiplexed operations, thus showing potential for online, integrated, dynamic, biomolecular analyses in vitro or in vivo, such as the dynamic metabolic analysis of single cells or organoids and point-of-care tests.

Start-up and maintenance of indigenous microalgae-bacteria consortium treating toilet wastewater through partial nitrification and nitrite-type denitrification

Microalgae-bacteria consortium (MBC) provides an alternative to sustainable treatment of human toilet wastewater (TWW) and resource recovery. This study compared the conventional activated sludge system and wastewater indigenous MBC system (IMBC) for nitrogen removal in TWW through the coupled partial nitrification (PN) and nitrite-type denitrification process. PN was firstly established by alternating FA and FNA. Subsequently, the successful PN maintenance with the nitrite accumulation rate ranging between 90.1–95.3% was achieved using two strategies: light irradiation with the appropriate specific light energy density at 0.0188–0.0598 kJ/mg VSS and the timely nitrite-type denitrification with the algae-secreted organics as the carbon source, eventually resulting in the nitrite accumulation rate ranging between 90.1–95.3%. In the IMBC-PN system, bacterial metabolism contributed to 91.5% of nitrogen removal and the rest was through microalgal assimilation. This study offers a sustainable hybrid IMBC-PN process for high NH4+-N strength wastewater treatment (e.g., TWW), which theoretically saves 23.5% aeration and 34.2% carbon source as well as reduces 17.0% sludge production.

Surface Environment and Energy Density Effects on the Detection and Disinfection of Microorganisms Using a Portable Instrument.

Real-time detection and disinfection of foodborne pathogens are important for preventing foodborne outbreaks and for maintaining a safe environment for consumers. There are numerous methods for the disinfection of hazardous organisms, including heat treatment, chemical reaction, filtration, and irradiation. This report evaluated a portable instrument to validate its simultaneous detection and disinfection capability in typical laboratory situations. In this challenging study, three gram-negative and two gram-positive microorganisms were used. For the detection of contamination, inoculations of various concentrations were dispensed on three different surface types to estimate the performance for minimum-detectable cell concentration. Inoculations higher than 103~104 CFU/mm2 and 0.15 mm of detectable contaminant size were estimated to generate a sufficient level of fluorescence signal. The evaluation of disinfection efficacy was conducted on three distinct types of surfaces, with the energy density of UVC light (275-nm) ranging from 4.5 to 22.5 mJ/cm2 and the exposure time varying from 1 to 5 s. The study determined the optimal energy dose for each of the microorganisms species. In addition, surface characteristics may also be an important factor that results in different inactivation efficacy. These results demonstrate that the proposed portable device could serve as an in-field detection and disinfection unit in various environments, and provide a more efficient and user-friendly way of performing disinfection on large surface areas.

Effects of Light Energy with Different Densities on Denitrification: Metabolic Intermediates, Electron Behavior, Enzyme Activities, and Sludge Settleability

Light energy, as one of the most influencing parameters in microalgal–bacterial consortium (MBC) systems, can regulate activities and metabolisms of microalgae and bacteria consortia. However, its effects on denitrifying bacterial remain unclear. Herein, variations of denitrification, microbial (denitrifiers’) metabolism, sludge surface characteristics, and settleability were systematically investigated with five light energy density conditions. Results showed that light energy decreased the denitrification rate with obvious accumulation of denitrifying intermediates (NO2– and N2O). This could be associated with the inhibition of light energy on electron behavior, evidenced from reduced nicotinamide adenine dinucleotide (by 67.0–71.3%), lowered electron transport system activity (by 66.7%), decreased denitrifying enzyme activities (e.g., NAR, NIR, and NOS), and downregulated gene expressions. Moreover, light energy worsened sludge settleability by regulating sludge extracellular polymeric substance (EPS) types, compositions, and surface characteristics. Specifically, light energy stimulated the soluble and lightly bounded EPS, as well as the hydrophilic and electronegative functional groups in EPS. These findings advance our understandings on denitrifiers activities and their electronic behavior responses to short-term light energy. Ultimately, this may promote the development of MBC as a sustainable approach for wastewater treatment.

Hidden-nucleons neural-network quantum states for the nuclear many-body problem

Understanding how protons and neutrons self-organize to form atomic nuclei requires solving the nuclear many-body Schr\"odinger equation. This work addresses this nontrivial task through a neural network quantum states ansatz that involves additional ``hidden'' degrees of freedom to improve the accuracy of the solution systemically. Light and medium-mass nuclei's energy and spatial density distributions are in excellent agreement with those obtained utilizing exact-diagonalization and diffusion Monte Carlo approaches.

Degradation of curcumin‐mediated photodynamic technology (PDT) on polycyclic aromatic hydrocarbons in oysters and toxicity evaluation of PDT‐treated oysters

SummaryThis study investigated the degradation effect of curcumin‐mediated photodynamic technology (PDT) on polycyclic aromatic hydrocarbons (PAHs) in oysters, and evaluated the safety of PDT‐treated oysters through acute and subacute toxicity experiments. The results demonstrated that curcumin‐mediated PDT could effectively degrade multi‐component PAHs in oysters, the maximum removal efficiency could reach 80.20% (10 μmol L−1 curcumin concentration and 54 J cm−2 light energy density). Acute toxicity experiment revealed PDT‐treated oysters did not cause any mortality and adverse symptoms in mice at an oral dose of 40 g kg−1 BW. Besides, after being treated at the dose of 10 g kg−1 BW for 28 days, the rats showed no obvious abnormal change in the indicators including the body weight, food utilisation, urology, haematology, serum biochemistry, organ index and histopathology. These findings show curcumin‐mediated PDT is a potentially efficacious method to degrade PAHs in oysters, and PDT‐treated oysters have high edible safety.

The first molecules in the intergalactic medium and halos of the Dark Ages and Cosmic Dawn

We study the formation and destruction of the first molecules at the epochs of the Dark Ages and Cosmic Dawn to evaluate the luminosity of the protogalaxy clumps (halos) in the molecular lines. The cosmological recombination is described using the RecFast model of an effective three-level atom, while the chemistry of the molecules is examined using the relevant basic kinetic equations. We then studied the effect of collisional and radiative excitation of molecules on the intensity of molecular emission in both warm and hot halos. Using the Planck data on the reionization of the intergalactic medium at z ∼ 6−8, we evaluated the upper limits of the light energy density for four models of thermal light from the first sources that appeared in the Cosmic Dawn epoch. Assuming that in the halos, the light energy density may essentially be even higher, we estimated the impact of the light from the first sources (the first light) on the formation and destruction of the first molecules in them as well as between them. We show that the molecules H2 and HD are destroyed by photodissociation processes shortly before the full reionization in the inter-halo medium, in the medium of both types of halos and for all models of the first light. At the same time, the number density of helium hydride ions, HeH+, shows essentially more complicated dependences on the kinetic temperature of halos and the models of the first light. These features characterizing the abundance of molecules also determine the intensity of the halos luminescence during their evolution. Furthermore, we calculated the evolution of the brightness temperature of the individual halo in the rotational lines of H2, HD and HeH+ molecules relative to the temperature of the cosmic microwave background at redshifts corresponding to the Dark Ages and Cosmic Dawn epochs. It does not exceed the microkelvin, but its detection may be an important source of information about the physical processes taking place at the beginning of the formation of the first stars and galaxies at the epochs of the Dark Ages and Cosmic Dawn.

Modeling photoacoustic pressure generation in colloidal suspensions at different volume fractions based on a multi-scale approach

Further development of quantitative photoacoustic tomography requires understanding the photoacoustic pressure generation by modeling the generation process. This study modeled the initial photoacoustic pressure in colloidal suspensions, used as tissue phantoms, at different volume fractions on a multi-scale approach. We modeled the thermodynamic and light scattering properties on a microscopic scale with/without treating the hard-sphere interaction between colloidal particles. Meanwhile, we did the light energy density on a macroscopic scale. We showed that the hard-sphere interaction significantly influences the initial pressure and related quantities at a high volume fraction except for the thermodynamic properties. We also showed the initial pressure at the absorber inside the medium logarithmically decreases with increasing the volume fractions. This result is mainly due to the decay of the light energy density with light scattering. Our numerical results suggest that modeling light scattering and propagation is crucial over modeling thermal expansion.

Controllable preparation of hierarchical MnCo bimetallic photocatalyst and the effect of atomic ratio on its photocatalytic activity

In recent years, bimetal has become an important branch of catalysis because of its unique interatomic synergistic activity. In this study, the effects of different preparation temperatures and atomic ratios on the activities of manganese-cobalt bimetallic photocatalysts and their catalytic mechanisms were investigated. Specifically, a series of hierarchical MnCo bimetals were prepared at 180 ∼ 200 ℃ with Mn:Co ratios of 2:1, 1:1 and 1:2 by a simple “hydrothermal/reduction” method. The results of the photoelectrochemical tests and density functional theory (DFT) show that the light absorption range, photocurrent, photovoltage and energy density of the materials are greatly affected by the preparation temperature and atomic ratio. The degradation rate of the representative MnCo2-190 bimetal to norfloxacin (NOR) reached 98.91% within 65 min. In addition to the characteristics of CoMn2 and MnCo, MnCo2 excites local surface plasmon resonance (LSPR) under light irradiation, resulting in strongest catalytic activity through Landau damping effect.

Slow Photon-Enhanced Heterojunction Accelerates Photocatalytic Hydrogen Evolution Reaction to Unprecedented Rates

Slow Photon-Enhanced Heterojunction Accelerates Photocatalytic Hydrogen Evolution Reaction to Unprecedented Rates

Effect of short-term light irradiation with varying energy densities on the activities of nitrifiers in wastewater

Microalgal-bacterial consortium (MBC) process has been proposed as an alternative to conventional activated sludge process for nitrogen removal from wastewater. As one of the most influencing parameters, light irradiation effects on microalgae have been extensively investigated. However, light influence on the performance of nitrifiers in activated sludge and its mechanism remains unclear. In this study, the effects of three factors (light irradiation power, irradiation time and sludge concentration) on activities and physiological characteristics of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) were systematically studied through both the Design of Experiments driven response surface methodology (RSM) approach and light-nitrification kinetic modeling. Results indicated that light irradiation with the specific light energy density (Es) at 0.0203–0.1571 kJ·mg−1 VSS (80–160 W/400–1000 μmol·m−2·s−1, 2.0–5.0 h and 2750–4250 mg·L−1) stimulated the relative AOB activities (rAOB) by 120.0%. This was supported by the increased electron transport system activity, key enzyme activity (AMO) , gene expression (amoA) and energy generation (ATP consumption) in the light treatment. Moreover, further Es increasing up to 0.18 kJ·mg−1 VSS inhibited both AOB and NOB activities. The inhibition was ascribed to the joint light responses of metabolic disorders and lipid peroxidation. The findings enhance our understanding of nitrifiers’ physiological responses to short-term light irradiation, and promote the development of MBC as a sustainable approach for wastewater treatment.

Magnetically induced transparency in helically structured periodic crystals.

We investigated the specific properties of magnetically induced transparency (MIT) and magnetically induced absorption (MIA) in helically structured periodic crystals (HSPCs). We showed that for the wavelength of MIT we have an ideal optical diode: The forward signal passes fully, while the backward signal is completely absorbed and not reflected. A formula for the wavelength λ_{t} of MIT and MIA resonance based on the numerical simulations was analytically obtained. The influence of HSPC parameters on the wavelength λ_{t} and on Δλ_{t}, the transparency line half width, was investigated by numerical simulations. The specific properties of light energy density, the ellipticity e_{in}, and azimuth φ_{in} of the total wave excited in the HSPC layer for MIT and MIA modes were investigated, too.

Особенности поглощения света в чирпированных одномерных фотонных кристаллах

The features of light absorption and localization in one-dimensional chirped photonic crystals (PCs) are studied. It is shown that although chirping leads to the loss of ideal periodicity, the integral over a wide spectral region light energy density practically does not change. We have shown that violation of the ideal periodic structure (chirping) can not only decrease the integral in the broad spectral region absorption, but also lead to an increase in this absorption in the PC, and this depends on the form of chirping and the form of modulation of the imaginary part of the dielectric permittivity. A study of the evolution of the absorption spectra when the chirping contrast is changed showed that at certain values of the chirping contrast, mini-zones of transmission appear in the photonic band gap, where significant absorption is observed.

Peculiarities of light absorption in chirped one-dimensional photonic crystals

The features of light absorption and localization in one-dimensional chirped photonic crystals (PCs) are studied. It is shown that although chirping leads to the loss of ideal periodicity, the integral over a wide spectral region light energy density practically does not change. We have shown that violation of the ideal periodic structure (chirping) can not only decrease the integral in the broad spectral region absorption, but also lead to an increase in this absorption in the PC, and this depends on the form of chirping and the form of modulation of the imaginary part of the dielectric permittivity. A study of the evolution of the absorption spectra when the chirping contrast is changed showed that at certain values of the chirping contrast, mini-zones of transmission appear in the photonic band gap, where significant absorption is observed. Keywords: chirped photonic crystals, absorption, light localization, coupled modes, chirping contrast, mini zone

Design of laser beam dump with high laser-induced-damage threshold

Laser beam dumps are necessary for laser systems designed to deliver high power or high energy to achieve effective control of stray light. However, the energy density of the stray light destroys the absorption glass of the beam dump with an increase in the output energy. To solve this problem, the initial laser-induced-damage threshold (LIDT) of a new optical absorption material was tested. A new type of laser beam dump was designed with this new optical material based on geometrical optics and light-field distribution analysis.

Light Irradiation Enables Rapid Start-Up of Nitritation through Suppressing nxrB Gene Expression and Stimulating Ammonia-Oxidizing Bacteria.

Nitritation facilitates the application of anaerobic ammonium oxidation (Anammox)-based processes for cost-efficient nitrogen removal from wastewater. This study proposed light irradiation as a novel strategy to rapidly start up nitritation by stimulating both the activities and growth of ammonia-oxidizing bacteria (AOB) while suppressing that of nitrite-oxidizing bacteria (NOB). Batch assays and kinetic model jointly suggested that AOB activity presented an initial increase followed by a decline while NOB decreased continuously throughout the light energy densities applied. Under optimal light energy densities (0.03-0.08 kJ/mg VSS), the highest nitrite accumulation ratio of 70.0% was achieved in sequencing batch reactors with both mainstream online and sidestream offline light treatments when treating real or synthetic municipal wastewater. Light irradiation induced different responses of AOB and NOB, leading to microbial structure optimization. Specifically, the expression of nxrB was downregulated, while the expression of amoA was upregulated under appropriate light irradiation. Moreover, although Nitrosomonas as typical AOB disappeared, the family Nitrosomonadaceae was doubled with enrichment of Ellin6067 and another four Nitrosomonadaceae genera that were only identified in light-treated reactors, thus ensuring AOB predominance and stable nitritation. These findings offer a new approach to rapidly establishing nitritation using light irradiation in municipal wastewater, especially for nitritation/microalgae system.