Peak Light Intensity Research Articles

Effects of Pulsed Light on Mycelium Growth and Conidiation in Aspergillus oryzae

Understanding how Aspergillus oryzae responds to light is critical for developing efficient light regulation strategies in the brewing and waste treatment industries. Although continuous light is known to restrict A. oryzae, little is known about A. oryzae’s sensitivity to light with photoperiod. In this study, we used pulse wave modulation (PWM) to generate nine pulsed blue light (PBL) treatments with varying peak light intensities and frequencies. The effect of PBL on A. oryzae was then compared to that of continuous blue light (CBL). Our findings showed that A. oryzae GDMCC 3.31 mycelium developed faster and produced more conidia under PBL with specific peak intensities and frequencies than under CBL treatment when the light dose and average light intensity were held constant. The colony diameter and conidia count under the two PBL treatments (PL-20_40%_1 Hz and PL-400_20%_10 kHz) were 1.13 and 1.22 times greater than under the CBL treatments, respectively. This different response may be mainly attributed to A. oryzae’s adaptation to the light–dark cycles in nature. Furthermore, an interactive effect was found between peak light intensity and frequency. This work includes pulsed wave modulation as a new factor that influences the A. oryzae photoresponse and recommends it in the development of light regulation methods for fermentation.

Study on defect imaging technology of optical elements based on micro-Raman spectroscopy.

An optical element defect detection imaging method based on micro-Raman spectroscopy is proposed to achieve high-precision imaging of optical element defects and their distribution. The detection precision of the system is immediately reflected in the imaging quality. The sharpness value of the mapping images is calculated using the Sum of Modulus of Gray Difference function. The selection of the Raman peak is an important step, and when a borosilicate glass sample with standard defects is measured for verification, it is found that the Raman peak light intensity changes at -37 and 28cm-1. When these two peaks were used for 2D mapping, obvious defect contours can be obtained, while the light intensity at other sites could not be used for imaging, and remained essentially constant. Through the detection of laser burning defects, new peaks appear at the burned defect location that could be used for imaging, and the burning defect area can be clearly distinguished from the non-burning area. By changing the laser burning conditions, the Raman shift changes, which verifies that there is a certain correlation between the laser burning degree and the Raman shift, which also provides a basis for 2D mapping imaging of defect detection.

Investigation of the effect of chirped factors on the interference enhancement effect of an Airyprime beam propagating in free space.

The first-order and the second-order chirped factors are imposed on the Airyprime beam, and the analytical expression of the chirped Airyprime beam propagating in free space is derived. The phenomenon that the peak light intensity on observation plane other than initial plane is greater than that on initial plane is defined as the interference enhancement effect, which is caused by the coherent superposition of the chirped Airyprime and the chirped Airy-related modes. The effects of the first-order and the second-order chirped factors on the interference enhancement effect are theoretically investigated, respectively. The first-order chirped factor only affects the transverse coordinates where the maximum light intensity appears. The strength of interference enhancement effect of the chirped Airyprime beam with any negative second-order chirped factor must be stronger than that of the conventional Airyprime beam. However, the improvement of the strength of interference enhancement effect caused by the negative second-order chirped factor is realized at the expense of shortening the position where the maximum light intensity appears and the range of interference enhancement effect. The chirped Airyprime beam is also experimentally generated, and the effects of the first-order and the second-order chirped factors on the interference enhancement effect are experimentally confirmed. This study provides a scheme to improve the strength of interference enhancement effect by controlling the second-order chirped factor. Compared with traditional intensity enhancement methods such as using lens focusing, our scheme is flexible and easy to implement. This research is beneficial to the practical applications such as spatial optical communication and laser processing.

Microalgal biofilm behavior under light/dark cycles

Biofilm-based systems have attracted more attention recently as an alternative to the standard suspended-cells process for microalgae cultivation. It has also been shown that cells can be protected from photoinhibition under intense sunlight when submitted to alternately light and dark cycles. However, the biological response to light variation is not well understood. Therefore, in this work, a mechanistic model is developed based on Han's model to describe photosynthesis and respiration dynamics that cover different cycle times and a wide range of light fractions (Light/Dark fractions). Keeping the same average light intensity, increasing the light frequency enhances growth thanks to reduced photoinhibition. Increasing light fraction improves the growth rate as both the peak light intensity and the dark period decrease. Respiration variation in intermittent light regimes is for the first time considered in this model, giving a better explanation of biofilm growth experimental data. Understanding the model response will guide strategies for growth enhancement, and further optimize biofilm reactor design and operation and eventually benefit biomass productivity.

Interference enhancement effect in a single Airyprime beam propagating in free space.

An analytical expression of a single Airyprime beam propagating in free space is derived. Upon propagation in free space, a single Airyprime beam in arbitrary transverse direction is the coherent superposition of the Airyprime and the Airy-related modes, which results in the interference enhancement effect under the appropriate condition. The Airy-related mode is the conventional propagating Airy mode with an additional π/2 phase shift and a weight coefficient of half the normalized propagation distance. Due to the peak light intensity in the initial plane being set to be 1, the strength of interference enhancement effect is characterized by the maximum light intensity. The maximum light intensity of a single Airyprime beam propagating in free space is independent of the scaling factor and is only decided by the exponential decay factor. When the exponential decay factor is above the saturated value, the interference enhancement effect disappears. When the exponential decay factor decreases from the saturated value, the maximum light intensity of a single propagating Airyprime beam increases, and the position of maximum light intensity is getting farther away. With the increase of the scaling factor, the position of maximum light intensity of a single propagating Airyprime beam is extended. The intensity distribution and the transverse Poynting vector of a single propagating Airyprime beam are demonstrated in different observation planes of free space. The flow direction of transverse energy flux effectively supports the interference enhancement effect of a single propagating Airyprime beam. The Airyprime beam is experimentally generated, and the interference enhancement effect is experimentally confirmed. The interference enhancement effect is conducive to the practical application of a single Airyprime beam.

Stroboscopic lighting with intensity synchronized to rotation velocity alleviates motion sickness gastrointestinal symptoms and motor disorders in rats.

Motion sickness (MS) is caused by mismatch between conflicted motion perception produced by motion challenges and expected “internal model” of integrated motion sensory pattern formed under normal condition in the brain. Stroboscopic light could reduce MS nausea symptom via increasing fixation ability for gaze stabilization to reduce visuo-vestibular confliction triggered by distorted vision during locomotion. This study tried to clarify whether MS induced by passive motion could be alleviated by stroboscopic light with emitting rate and intensity synchronized to acceleration–deceleration phase of motion. We observed synchronized and unsynchronized stroboscopic light (SSL: 6 cycle/min; uSSL: 2, 4, and 8 cycle/min) on MS-related gastrointestinal symptoms (conditioned gaping and defecation responses), motor disorders (hypoactivity and balance disturbance), and central Fos protein expression in rats receiving Ferris wheel-like rotation (6 cycle/min). The effects of color temperature and peak light intensity were also examined. We found that SSL (6 cycle/min) significantly reduced rotation-induced conditioned gaping and defecation responses and alleviated rotation-induced decline in spontaneous locomotion activity and disruption in balance beam performance. The efficacy of SSL against MS behavioral responses was affected by peak light intensity but not color temperature. The uSSL (4 and 8 cycle/min) only released defecation but less efficiently than SSL, while uSSL (2 cycle/min) showed no beneficial effect in MS animals. SSL but not uSSL inhibited Fos protein expression in the caudal vestibular nucleus, the nucleus of solitary tract, the parabrachial nucleus, the central nucleus of amygdala, and the paraventricular nucleus of hypothalamus, while uSSL (4 and 8 cycle/min) only decreased Fos expression in the paraventricular nucleus of hypothalamus. These results suggested that stroboscopic light synchronized to motion pattern might alleviate MS gastrointestinal symptoms and motor disorders and inhibit vestibular-autonomic pathways. Our study supports the utilization of motion-synchronous stroboscopic light as a potential countermeasure against MS under abnormal motion condition in future.

Three-dimensional echo distribution analysis of multi-band and oblique Gaussian beams propagating through cat-eye optical system

The cat-eye effect in optical systems enables active laser detection at long distances and high orientation precision. However, few studies focus on the influence of a multi-band laser with a large incident angle on the echo distribution. This study proposes a three-dimensional echo distribution calculation model of an obliquely incident multi-band laser based on the Collins diffraction integral formula and aperture function expansion as the sum of complex Gaussian functions. The echo distributions for different detection ranges are calculated by coupling the size of the detector in a cat-eye optical system into the model. In the numerical simulation, the influences of laser wavelength, incident angle, and target detector parameter are quantitatively analysed by introducing a target-missing quantity of echo spot and peak light intensity. The results show that the peak light intensity decreases with an increase in incident laser wavelength. When the incident angle increases to a particular value, the peak light intensity decreases sharply, and the target-missing quantity of the echo spot centroid is positively correlated with the incident angle. We can effectively extract important information, such as the working band and detector size, from the cat-eye target echo using this model and provide a trajectory prediction theory for the active detection of a cat-eye target moving at high speed.

Stable CsPbX3/ZnO Heterostructure Nanocrystals for Light-Emitting Application.

Lead halide perovskite nanocrystals (PNCs) are attractive in light-emitting applications with their extraordinary photoluminescent property. However, the inherent instability of mixed Br/I ions poses a major hurdle to the practical application of yellow-red emitting PNCs. In this work, we report the growth of crystalline ZnO on the surface of CsPb(Br/I)3 nanocrystals through a ligand-mediated in situ surface reaction route, which forms monodispersed CsPb(Br/I)3/ZnO heterostructure nanocrystals (PZNCs). The unique heterostructure endows the PZNCs with largely enhanced stability against air, moisture, and polar solvents. Notably, the red-emitting PZNCs exhibit high color quality and superior stability compared with classical CsPb(Br/I)3 PNCs. The PZNCs retain 95% of initial luminescence after 500 h of illumination, and the PZNC-converted red-light LEDs show no obvious change in the peak position and light intensity after continuous operation for 100 h, demonstrating the promising prospect of the materials in light-emitting applications.

LIGHT SPECTRA: AN IMPORTANT CONSIDERATION FOR CIRCADIAN ALIGNMENT IN THE MEDICAL ICU

TOPIC: Sleep Disorders TYPE: Original Investigations PURPOSE: Human circadian rhythms are regulated by a central ‘master clock’ which is entrained (i.e., aligned) to the 24-hour day primarily by light. Bright daytime light and lack of nighttime light are key entrainment signals. Light is detected via retinal photoreceptors, of which melanopsin is the primary circadian receptor. Circadian rhythms are best entrained by light wavelengths between 446 and 477 nanometers (nm), which are dominant in sunlight. Light wavelengths outside of this range will fail to optimally activate circadian photoreceptors and thus will not promote circadian alignment. A lack of activating wavelengths in hospital settings may potentiate circadian misalignment; circadian misalignment is associated with poor outcomes in critically ill patients.Light spectra measurements provide the intensity, or relative presence, of wavelengths within a defined range. Our study aims to determine the intensity of wavelengths within the approximate visible light range (380-780 nm) in patient rooms in two medical intensive care unit (MICU) campuses in a tertiary academic hospital system. We hypothesized that, during the day, MICU room lighting lacks significant presence of wavelengths between 446 and 477 nm. METHODS: To test this, we conducted an observational study of the visible spectra in 13 MICU rooms. Spectra were captured at 09:00, 13:00, and 17:00 on a sunny and cloudy day each month for 3 months, with a plan to continue for a full year. To test the contribution of artificial light, the spectra of each light source in the room was measured at night. All readings were taken from a standard location at the head of the patient bed. RESULTS: Rooms in both MICUs revealed common peak light intensities at 545 nm and 611 nm at all time points. These wavelengths align with the two wavelengths of greatest intensity emitted by artificial lights in the MICU. On average, 40% of measured intensities came from artificial room lighting, with MICU 1 having a higher percentage (46%) than MICU 2 (31%). Within the total visible spectrum, wavelengths between 446 and 477 nm had a greater daily contribution in MICU 2 (12%) than MICU 1 (8%). MICU rooms with west facing windows had a higher percentage of artificial light present in their spectra (52%) compared to rooms with east facing windows (35%). Similarly, rooms with east-facing windows demonstrated greater relative intensity of wavelengths between 446 and 477 nm (11%) compared to west-facing windows (7%). Over the day, as expected, room light spectra progressively shifted away from natural light, with late afternoon having a strong percentage of artificial spectra. CONCLUSIONS: The wavelengths of greatest intensity present during the day in MICU rooms are outside of the range known to optimally activate retinal photoreceptors that signal day-night orientation. Patients receive insufficient light reflecting natural sunlight, thus, our MICU room lighting likely fails to entrain patient circadian rhythms. CLINICAL IMPLICATIONS: Circadian misalignment has been associated with cardiovascular, immune, metabolic, and neurologic dysfunction, and in critically ill patients, death. ICUs contain myriad factors that disrupt circadian rhythms. The particular wavelengths of light patients are exposed to must be closely considered in the environment of care so that patients have the opportunity to remain entrained in order to heal. DISCLOSURES: No relevant relationships by Taylor Intihar, source=Web Response No relevant relationships by Melissa Knauert, source=Web Response No relevant relationships by Katherine Wasden, source=Web Response

Outdoor scale‐up of Leptolyngbya sp.: Effect of light intensity and inoculum volume on photoinhibition and ‐oxidation

The effect of light intensity and inoculum volume on the occurrence of photooxidation for Leptolyngbya sp. QUCCCM 56 was investigated, to facilitate the transition from small‐scale laboratory experiments to large‐scale outdoor cultivation. Indoor, the strain was capable of growing at light intensities of up to 5600 µmol photons/m2/s, at inoculation densities as low as 0.1 g/L (10% inoculation volume vol/vol). Levels of chlorophyll and phycocyanin showed a significant decrease within the first 24 h, indicating some level of photooxidation, however, both were able to recover within 72 h. When cultivated under outdoor conditions in Qatar during summer, with average peak light intensities 1981 ± 41 μmol photons/m2/s, the strain had difficulties growing. The culture recovered after an initial adaptation period, and clear morphological differences were observed, such as an increase in trichome length, as well as coiling of multiple trichomes in tightly packed strands. It was hypothesized that the morphological changes were induced by UV‐radiation as an adaptation mechanism for increased self‐shading. Furthermore, the presence of contaminating ciliates could have also affected the outdoor culture. Both UV and contaminants are generally not simulated under laboratory environments, causing a mismatch between indoor optimizations and outdoor realizations.

Phase-shift interferometry measured transmission matrix of turbid medium: Three-step phase-shifting interference better than four-step one

Transmission matrix (TM) is an important tool for controlling light focusing, imaging, and communication through turbid media. It can be measured by 3-step (TM3) or 4-step (TM4) phase-shifting interference, but the similarities and differences of the transmission matrices obtained by the two methods are rarely reported. Therefore, we make a quantitative comparison of the peak light intensity, signal-to-noise ratio, and average background of 24 × 24 = 576 focal points between paired samples (TM3–TM4) through the Wilcoxon rank sum test, and discuss the singular value of the transmission matrix and the focal peak. The comparative results of peak light intensity and signal-to-noise ratio show that there is a significant difference between the 3-step phase shift and the 4-step phase shift transmission matrixes. The focusing effect of the former is significantly better than that of the latter; interest concentrates on the focal intensity and singular value. The reciprocal of the singular value is proportional to the squared intensity, which is in accordance with singular value theory. The results of comparison of peak light intensity and signal-to-noise ratio strongly suggest that 3-step phase shift should be selected and used in applying the phase shift method to the measurement of the transmission matrix; and the singular value is of great significance in quantifying the focusing, imaging, and communication quality of the transmission matrix.

Abstract 25: Skeletonema marinoi (diatom) extracts are endowed with promising cancer preventive properties in prostate cancer cells

Abstract The exploration of natural antioxidants for nutraceuticals and pharmaceuticals industries has recently increased. In this scenario, marine microorganisms, represent underestimated sources of bioactive products endowed with beneficial effects on health, that include anti-oxidant, anti-tumor and anti-angiogenic activities. Here, we tested the potential cancer preventive activities of extracts from the marine coastal diatom Skeletonema marinoi Sarno and Zingone (CCMP 2092) on prostate cancer cells, in vitro. Skeletonema marinoi was grown under a sinusoidal light distribution with a midday peak of 150 μmol photons m−2 s−1, and then, once cells reached the exponential phase, shifted to a sinusoidal light distribution with a higher midday peak light intensity of 600 μmol photons m−2 s−1. This high light condition induces in cells the synthesis of antioxidant and protective molecules. Total wet biomass was collected and chemically extracted by methanol solvent. The dried extract was tested as a food supplement on prostate (PC-3), as compared to normal prostate epithelium. Gene expression analysis was performed by qPCR, measuring the variation of 365 different genes involved in the apoptosis and immunogenic cell death pathways. Treatments with Skeletonema marinoi extracts (1-10-100 µg ml-1) resulted in a statistically significant, dose dependent, antiproliferative (inhibition at 70% of cell viability at 100 µg ml-1) and pro-apoptotic effects in PC-3 cells, while sparing normal epithelial prostatic cells. Among the gene panel analysed as key indicators of the PC3 cell fate in terms of signalling pathway prediction, we observed up/down regulation of APAF1, BAD, BAG1, BAG3, BAK1, BAX, BCL2, BCL2L1, BCL2L13, BCL2L2, BCL3, BDNF, BECN1, BFAR, BID, BIK, BIRC2, BIRC3, BIRC6, BNIP1, BOK, BRAF, BRCA1, BRE, CARD17, CARD9, CASP1-2-3-4-5-6-7-10-14, CBX4, CRADD, DEDD, DHCR24, FADD, FAS, FASLG, FASTK. The integrated gene expression analysis revealed necroptosis activation in cells with the up-regulation of the inflammatory mediators such as F2R, F2, IL18-19-A-31RA, SOCS2, SOCS3 genes and the downregulation of the angiogenic factors such as ALOX12, ALOX15B, PIK3CA, PIK3R2, and VEGF genes. One of the main candidates as compounds responsible for such cancer preventive activities is the diatom-xanthophyll photoprotective diatoxanthin, probably in synergy with other molecules. Further metabolomics analysis on the extracts will help in understanding and interpretation of the results. These results demonstrate promising cancer preventive activities of Skeletonema marinoi extracts in PC3 cell lines. This confirms microalgal-derived drugs as potential relevant source of nutraceutical novel food and candidate as potential dietary intervention in cancer prevention approaches. Citation Format: Clementina Sansone, Piscitelli Concetta, Galasso Christian, Smerilli Arianna, Bruno Antonino, Noonan Douglas, Albini Adriana, Brunet Christophe. Skeletonema marinoi (diatom) extracts are endowed with promising cancer preventive properties in prostate cancer cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 25.

Uric acid detection by using contactless intensity modulation based displacement sensor

A simple and contactless intensity modulated displacement sensor is proposed and demonstrated for sensing uric acid concentration. For a concentration change of uric acid from 0 ppm to 500 ppm, two peak voltages are obtained from the displacement curve correspond to the highest reflectivity of each concentration. Those peak light intensities increase linearly with the concentration due to the increase of the refractive index of the uric acid solution. This implies that the higher concentration of uric acid tends to detect a stronger signal. The measured sensitivities are obtained at 0.0015 V/ppm and 0.0016 V/ppm for the first peak voltage and second peak voltage respectively. The result showed the percentage of similarity for the first peak to the second peak is almost 94% and the linearity more than 97% for both peak voltages is obtained suggested the consistency of the sensor system. The stability and simplicity of the contactless sensor offer a good and valuable opportunity for many applications especially in the hazardous chemical, pharmaceutical, process control and diagnostic sectors.

Complex diffraction and dispersion effects in femtosecond laser writing of fiber Bragg gratings using the phase mask technique.

The combined effect of chromatic dispersion and conical diffraction (i.e., off-plane diffraction) in femtosecond laser inscription of fiber Bragg gratings using the phase mask technique is characterized by measuring the light intensity distribution after the phase mask. As the distance from the mask and the observation point grows, chromatic dispersion and conical diffraction introduced by the mask gradually decrease the peak intensity inside the line-shaped focal volume of the cylindrical lens that is used to focus the femtosecond pulses inside the fiber. We also show that at a certain distance from the mask spherical aberration introduced by the plane-parallel mask substrate is cancelled out by conical diffraction and, at a different distance, chromatic aberration of the cylindrical lens is cancelled out by chromatic dispersion of the mask. These two independent cancellation effects lead to sharpening of the line-shaped focus and the consequent growth of peak light intensity inside it. The above phenomena become especially pronounced for tightly focused femtosecond laser beams and small-pitch phase masks, which, in turn, allows one to choose experimental conditions to inscribe Bragg gratings in polymer-coated non-sensitized 50 µm fibers.

An Analysis of ZnS:Cu Phosphor Layer Thickness Influence on Electroluminescence Device Performances

Electroluminescence (EL) device is a new technology; its thickness is within micrometer range which can bend more easily and emit light. However, the thickness of ZnS:Cu phosphor layer may affect the light intensity, so we have analyzed the thickness of ZnS:Cu phosphor layer on EL device. The EL devices consist of ITO:PET/ZnS:Cu phosphor/insulator (BaTiO3)/Ag electrode. The EL devices were fabricated in changing thickness 10 μm, 30 μm, and 50 μm. At 100 V 400 Hz, the luminance of EL devices was 51.22 cd/m2 for thickness 30 μm more than that of 45.78 cd/m2 (thickness: 10 μm) and 42.58 cd/m2 (thickness: 50 μm). However, the peak light intensity was achieved at wavelength of 507 nm which was not influenced by the thickness of the ZnS:Cu phosphor. The use of the ZnS:Cu phosphor layer at thickness 30 μm in the EL device significantly improves the luminescence performance.

Fabrication of carbon nanotubes/TiO2 nanoparticles electrode-based on electrochemiluminescence (ECL) cell application

Abstract In this paper, we fabricate an electrochemical luminescence (ECL) cell with carbon nanotubes/TiO 2 nanoparticles (CNT-TNPs) layer and coated on F-doped SnO 2 (FTO) glass can be increased the surface area interface with the Ru(II) complex [Ru(bpy) 3 Cl 2 ]. The investigated ECL cells were composed of FTO glass/ Ru(II) complex [Ru(bpy) 3 2+ ]/ CNT-TNPs electrode/ FTO glass, which compared TNP and bare FTO electrode. The luminance property of the ECL cell with CNT-TNPs electrode was 59 cd/m 2 more than bare FTO electrode up to 61%. Also, the threshold voltage of the light emission from ECL cell was 2.25 V for CNT-TNPs electrode, which was lower than that 2.5 V for TNP, and 3.0 V for bare FTO electrode. The high efficiency of the ECL cell with CNT-TNPs measured at 4 V was 0.13615 lm/W and 0.13137 lm/W, while bare FTO electrode measured at 4.75 V was 0.10213 lm/W. The peak light intensity at wavelength was 622 nm which corresponds to a red-orange color. The use of the CNT-TNPs electrode layer coated on FTO glass significantly improves the light intensity performance.

Effects of electrical and optical properties of thickness condition of ZnO nanorod array layer for efficient electrochemical luminescence cell device

In this paper, we report on electrochemical luminescence (ECL) cells with a ZnO nanorod (ZNR) layer. The investigated ECL cells were composed of F-doped SnO2 (FTO) glass/Ru(II)/ZNRs/FTO glass, which used a ZNR layer as an electrode and the Ru(II) complex [Ru(bpy)32+] as a light-emitting material. The ECL cells were fabricated by changing the thickness of ZNRs from 5 to 12.5 µm. The luminescence property of the ECL cells was strongly affected by the variation in the thickness of the ZNR layer. The threshold voltage for the light emission from the ECL cells was 2 V for 10 µm thick ZNRs, which was lower than that of the thickness of the ECL cells without a ZNR layer. Also, the intensity of luminance from the ECL cells with ZNRs was much higher than that from the ECL cells without ZNRs at the same operating voltage. The efficiency of the ECL cells without ZNRs measured at 3 V was 0.0049 lm/W, while those of the ECL cells with ZNRs were 0.0121, 0.0157, 0.0354, and 0.024 lm/W for the ZNRs layer thicknesses 5, 7.5, 10, and 12.5 µm, respectively. However, the peak light intensity at the wavelength was 623 nm which had not affected the all ZNRs thicknesses. The best lifetime of the ECL cells with these thicknesses was 40 min for ZNRs 10 µm. The use of the ZNR layer in the ECL cells significantly improves the luminescence performance.

Arc Flash Light Intensity Measurement System Design

Electrical arcs emit extremely high intensity light across a wide spectrum that can damage the eye's delicate structures, such as the cornea or the retina. Developing industry safety standards to mitigate light hazards is a critical component of arc flash safety. Accurate measurement of light intensity is the first step in understanding the level of eye protection needed. Traditionally, light measurement devices are an assembly of light-detecting resistors made from cadmium sulfide (CdS) or silicon (Si) cells. However, their response times are inadequate for capturing the peak light intensity or the dynamic changes during the initial arc flash. In addition, the brightness of an arc flash is greater than the measurable light levels from traditional light measurement devices. Furthermore, the light sensitivity of traditional sensors does not match the Commission Internationale de l'Éclairage luminosity function <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V(\lambda)$</tex-math></inline-formula> curve, which defines the human eye's sensitivity to bright light as a function of wavelength under typical ambient light conditions. This paper discusses a novel light measurement technique to overcome the limitations of traditional approaches. This design is capable of measuring the light intensity of the arc flash as perceived by the human eyes. These results can be used to evaluate the potential of an arc flash to harm the eyes.

Use of Diode Analogy in Explaining the Voltammetric Characteristics of Immobilized Ferrocenyl Moieties on a Silicon Surface

AbstractThe creation of a model that explains the dependency of the voltammetric characteristics of ferrocene‐terminated Si (Si‐Fc) samples on the type of substrate (n‐ or p‐type) would be helpful in understanding the electronic characteristics of these materials. To explain the dependency, Si‐Fc samples are treated like diodes. As diodes, the samples may allow charge flow in a certain direction while inhibiting the opposite flow. The treatment of a sample as a diode is done to facilitate analysis of charge flow within the sample, thus enabling easy prediction of its electrochemical characteristics. Likewise, the trend of the anodic peak potential versus light intensity plot (of the samples with n‐type substrate) is also associated with the sample’s diode characteristics. Our proposed model opens many scientific possibilities, especially in relating the voltammetric characteristics of electroactive molecules on a Si surface with the properties of a diode (e.g., open‐circuit voltage).

Numerical modeling of an InAsSb/InAsSbP double heterojunction light emitting diode for mid-infrared (2–5 μm) applications

The numerical model of a Mid-infrared (MIR) P+–InAs0.48Sb0.22P0.30/n0–InAs0.89Sb0.11/N−–InAs0.48Sb0.22P0.30 double heterostructure light emitting diode (DH-LED) has been reported in this paper. The governing equation of the structure has been solved numerically under the condition of high injection using fourth order Runge-Kutta method employing the shooting algorithm. The numerical model takes into account all dominant radiative and non-radiative recombination processes, surface recombination velocity and self-absorption in the active layer of DH-LED. The DH-LED has been simulated for mid-infrared applications by considering modulation bandwidth and its dependence on active layer width, doping concentration, and injected carrier density. The effect of surface recombination velocity on the quantum efficiency, peak light intensity for different values of active layer width and doping concentration has been estimated numerically. The rise time of the structure has been evaluated by considering transient response for a step current of 50mA. The output power of DH-LED has been computed as a function of bias current and compared/ contrasted with the reported analytical and experimental results.