Konsep perubahan intensitas cahaya terhadap jarak memerlukan metode pengukuran yang memberikan ketepatan dalam menghasilkan data. Aplikasi light meter pada smartphone digunakan dalam penelitian ini ...untuk mengukur penjumlahan intensitas cahaya (I) dari dua sumber cahaya. Daya lampu divariasikan untuk mendapatkan data intensitas cahaya pada jarak dan daya lampu yang berbeda. Hasil perolehan intensitas cahaya untuk ketiga variasi adalah 6,2746 Cd dan 5,8546 Cd, 9,8808 Cd dan 9,6650 Cd, serta 12,8302 dan 11,9215. Diperoleh iluminasi (E) sebesar 32,59671 lux dan 26,964 lux, 51,3220 lux dan 44,9105 lux, serta 43,9934 lux dan 37,1495 lux. Hasil dari intesitas cahaya dan iluminasi yang diperoleh pada ketiga variasi berbanding terbalik dengan kuadrat jaraknya. Semakin jauh light meter diletakan dari sumber cahaya, nilai intensitas cahaya dan iluminasinya semakin kecil. Hal ini sesuai hukum keterbalikan kuadrat pada hukum fisika yang menyatakan sumber pancaran berbanding terbalik dengan kuadrat jaraknya.
•Efficient rutile photocatalysts obtained by the reverse micelle and low temperature methods.•Monitoring of the degradation kinetics using light reflected from the TiO2 suspension.•Effect of H2O2 on ...the CR, MO and DR23 dyes photodegradation was evaluated.
The study proposes two new TiO2 photocatalysts with excellent photocatalytic properties obtained by the reverse micelle (RM-TiO2) and low temperature (LT-TiO2) methods. The crystal structure and morphology of the obtained TiO2 samples were analyzed by X-ray diffraction, scanning electron microscopy and IR-spectroscopy. The chosen synthesis conditions lead to pure rutile modification. FTIR spectra of the obtained samples contain characteristic bands, attributed to stretching vibrations of Ti–O bonds and to deformation vibrations of Ti–OH bonds. The average crystallite sizes for RM-TiO2 and LT-TiO2 samples are 5.4 and 9 nm, respectively. SEM analysis showed that the RM-TiO2 consists of TiO2 particles, assembled into spherical aggregates, while LT-TiO2 consists of smaller aggregates and is mostly mesoporous. The BET surface areas of the RM-TiO2 and LT-TiO2 samples are 39 and 63 m2/g, respectively. The photocatalytic degradation of the Congo Red (CR), Methyl Orange (MO) and Direct Red 23 (DR23) dyes in water medium has been studied under UV LED irradiation with H2O2 as an auxiliary oxidant. Both the RM-TiO2 and LT-TiO2 samples are active photocatalysts. The optimal dosages are 1.5 and 0.5 g/L respectively. The maximum photodegradation efficiency of RM-TiO2 is observed when the concentration of H2O2 is 15 mM for CR, 5 mM for MO and 10 mM for DR23. The maximum photodegradation efficiency of LT-TiO2 is observed when the concentration of H2O2 is 10 mM for CR, 2.5 mM for MO and 1.5 mM for DR23. The boosting effect of H2O2 on the degradation efficiency can be explained by an increased generation of •OH radicals. The real-time monitoring of degradation kinetics has been performed using measurements of light reflected from TiO2 suspension. The proposed technique allows the use of small volume of solution and amount of photocatalyst. The synthesized rutile photocatalysts may be used for wastewater treatment.
The paper discusses the phenomena accompanying switching the sinusoidal excitation of an antenna on and off when the antenna is excited by a train of sinusoids containing several to several hundred ...periods. Transient phenomena are presented against the background of the resonant properties of the antenna. The processes of turning the antenna on and off take place under different conditions and therefore are different. When the antenna is switched on, the transient processes are determined by the antenna properties and the excitation properties. When the antenna is switched off, excitation is no longer present, and the properties of the antenna determine the transient process. We define a new measure of time: the effective light meter.
Light exposure affects the circadian system and consequently can affect sleep quality. Only few studies examined this relationship in children. We evaluated associations between light exposure ...patterns and sleep metrics in children. We measured the sleep parameters of 247 Dutch children, aged between 11 and 13 years and recruited from the ABCD cohort, using actigraphy and sleep records for 7 consecutive nights. Personal light exposures were measured with a light meter during the whole day and night. We applied generalized mixed-effects regression models, adjusted for possible confounders, to evaluate the associations of light exposure patterns on sleep duration, sleep efficiency and sleep-onset delay. In the models mutually adjusted for potential confounders, we found the amount of hours between the first time of bright light in the morning and going to sleep and the duration of bright light to be significantly associated with decreased sleep duration (in min; β: -2.02 95% confidence interval: -3.84, -0.25, β: -8.39 95% confidence interval: -16.70, -0.07, respectively) and with shorter sleep-onset delay (odds ratio: 0.88 95% confidence interval: 0.80, 0.97, odds ratio: 0.40 95% confidence interval: 0.19, 0.87, respectively). Increased light intensities at night were associated with decreased sleep duration (T2 β: -8.54 95% confidence interval: -16.88, -0.20, T3 β: -14.83 95% confidence interval: -28.04, -1.62), while increased light intensities before going to bed were associated with prolonged sleep onset (odds ratio: 4.02 95% confidence interval: 2.09, 7.73). These findings further suggest that children may be able to influence their sleep quality by influencing the light exposure patterns during day and night.
Modern lightmeters are analyzed and the results of the development of a luxmetre with a dynamic range of ten orders and the methods of studying its metrological characteristics are presented, ...according to which the nonlinearity of the energy characteristic of the sensitivity of the luxmetre does not exceed ± 0,7 % in the range of illumination (1 · 10-5 – 1 · 105) lux, and the limits of the permissible basic relative error of measuring the illumination do not exceed ± 5 %.
To compare methods to measure time outdoor and light levels, two possible predictors of myopia, in Singapore children.
Outdoor time from a diary and portable light meter over a 1-week period was ...compared in 117 Singapore children aged 6-12 years with and without myopia. All children wore a (HOBO Pendant temp/light Part # UA-002-64) light meter for 1 week and the parents filled the 7-day outdoor diary to track the outdoor activity.
Mean outdoor time from diary and time with light levels was 5.44 hours per week and 7.91 hours per week, respectively, during school term and school holidays. Time spent with light levels of >1000 Lux from the light meter were 7.08 h per week and 9.81 h per week, respectively, during school term and school holidays. The intraclass correlation coefficients were 0.21 and 0.28 for outdoor time from the diary and light meter (1000 Lux cut-off) during the school term and holidays, respectively. The correlation coefficient was 0.34 (95% CI 0.05, 0.58) for a weekday during school holidays, 0.17 (-0.14, 0.45) for a weekday during school term, 0.07 (-0.16, 0.29) for a weekday during school term, and 0.25 (0.02, 0.46) for a weekend during school term.
The agreement between the light meter and 1-week diary was poor to fair. Both instruments measure different parameters, time outdoors and light intensity, and could therefore capture different aspects of risk in future myopia studies.
Light is one of the most important factors for photosynthetic organisms to grow. Historically, the amount of light in plant sciences has been referred to as light intensity, irradiance, ...photosynthetic active radiation, photon flux, photon flux density, etc. On occasion, all these terms are used interchangeably, yet they refer to different physical units and each metric offers distinct information. Even for experts in the fields of plant photobiology, the use of these terms is confusing, and there is a loose implementation of each concept. This makes the use of radiometric units even more confusing to non-experts when looking for ways to measure light, since they could easily feel overwhelmed by the specialized literature. The use of scientific concepts must be accurate, as ambiguity in the use of radiometric quantities can lead to inconsistencies in analysis, thus decreasing the comparability between experiments and to the formulation of incorrect experimental designs. In this review, we provide a simple yet comprehensive view of the use of radiometric quantities in an effort to clarify their meaning and applications. To facilitate understanding, we adopt a minimum amount of mathematical expressions and provide a historical summary of the use of radiometry (with emphasis on plant sciences), examples of uses, and a review of the available instrumentation for radiometric measurements.
Incoming solar radiation is an important driver of aquatic ecosystem processes, such as gross primary production and photodegradation of organic matter. Rates of incoming solar radiation can be ...estimated in several ways, but their utility is limited for collecting a large number of replicate samples needed to quantify variation in light availability within and among streams. We evaluated the utility of 2 photodegrading organic dyes (rhodamine WT RWT and fluorescein) for measuring light exposure, especially at the level of the stream bed. We attached vials with known concentrations of the RWT or fluorescein to the stream bed and used regressions of concentration vs accumulated light to estimate photodegradation rates. Initial concentrations of RWT (20–100 µg/L) did not affect rate of photodegradation, but RWT decay rates were 93% slower in the dark than in the light. We also tested fluorescein, which degrades faster than RWT when exposed to light and is stable when kept in the dark. On average, RWT degraded at a slower rate (3.5 µg L−1 d−1) than fluorescein (40.8 µg L−1 d−1) when exposed to similar levels of light accumulation. Water temperature did not affect the decay rate of RWT at 10 or 20°C, but RWT did not decay significantly at 30°C, a result suggesting that high temperatures might affect decay rates differently than lower temperatures. Water temperature did not affect the decay rate of fluorescein. The strength of this method is that it enables researchers to integrate light measurements into a single value. Researchers can deploy multiple arrays within a reach to develop a relative measure of incoming light that has the potential to cover large spatial and temporal scales.
The monitoring process is important for any structure for many reasons, but unfortunately most of Iraqi constructions suffer from the lack of their drawings and plans due to different reasons. Such ...drawings and plans are very important in monitoring process to identify locations of damages, thus a new approach has been applied to monitor highway bridges damages using accurate digital cameras with GPS to determine locations of the damages in site, then such defined locations axis have been used to obtain the related Google images of the site to locate the position of damages on images. Also a new colored code of arrows has been used to locate the damage position and identify the direction of images. It has been proved that using such approach was very successful and will reduce time and efforts due to their activity, accuracy and easiness of both damages recognition or identification of damages location when compared with respect to the traditional method of monitoring process as well as the new approach was essential to solve the problem of missing drawings and plans of the site.
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