A simple adaptive difference algorithm with CO2 measurements for evaluating plant growth under environmental fluctuations.

OBJECTIVE: The aim of this study is to demonstrate an adaptive method that is robust toward environmental fluctuations and provides a real-time measure of plant growth by measuring CO2 consumption. To verify the validity of the proposed method, the relation between the plant growth and variation in light conditions with a closed experimental system was investigated. RESULTS: The proposed method was used to measure the photosynthetic rate induced by photosynthetic photon flux density (PPFD) and to evaluate plant growth under continuous and pulsed light in arugula plants. The PPFD-dependent change in photosynthetic rate was measured. And in the condition range of 200-10,000 µs pulse period and 50% duty ratio of pulsed light, there was no change in the growth rate of plants assuming the same PPFD as continuous light. These experiments showed the validity of the adaptive method in removing environmental fluctuations without precise control of temperature and humidity.

Optical Properties of Pickering Emulsions and Foams.

A significant number of studies have been conducted on particle adhesion phenomena as pertaining to the oil-water interface of droplets and the air-liquid interface of bubbles, known as Pickering emulsions and Pickering foams, respectively. However, few of the literature reports have discussed the optical properties of these materials. In this study, the optical properties of Pickering particles were calculated by using an electromagnetic field analysis via a finite element method, and their optical responses are discussed. The changes in scattering due to the differences in the number of adhering particles and particle size are compared for three composition systems: an oil-in-water Pickering emulsion, a water-in-oil Pickering emulsion, and a Pickering foam. It was determined that changes in the amount of scattering are due to the mixing of the phases in the scattering field. This effect is more pronounced when the size of the scatterer is significantly smaller than the wavelength. For systems with particles larger than the wavelength, changes in the amount of scattering were suppressed because of destructive interference of the electromagnetic waves. This work revealed that the variation in the amount of scattering due to the constituent material and size of the Pickering particles is affected by two different factors, and the change in the amount of scattering is 10 times greater than in a uniformly dispersed system.

Demonstration of laser biospeckle method for speedy in vivo evaluation of plant-sound interactions with arugula.

In recent years, it is becoming clearer that plant growth and its yield are affected by sound with certain sounds, such as seedling of corn directing itself toward the sound source and its ability to distinguish stuttering of larvae from other sounds. However, methods investigating the effects of sound on plants either take a long time or are destructive. Here, we propose using laser biospeckle, a non-destructive and non-contact technique, to investigate the activities of an arugula plant for sounds of different frequencies, namely, 0 Hz or control, 100 Hz, 1 kHz, 10 kHz, including rock and classical music. Laser biospeckles are generated when scattered light from biological tissues interfere, and the intensities of such speckles change in time, and these changes reflect changes in the scattering structures within the biological tissue. A leaf was illuminated by light from a laser light of wavelength 635 nm, and the biospeckles were recorded as a movie by a CMOS camera for 20 sec at 15 frames per second (fps). The temporal correlation between the frames was characterized by a parameter called biospeckle activity (BA)under the exposure to different sound stimuli of classical and rock music and single-frequency sound stimuli for 1min. There was a clear difference in BA between the control and other frequencies with BA for 100 Hz being closer to control, while at higher frequencies, BA was much lower, indicating a dependence of the activity on the frequency. As BA is related to changes from both the surface as well as from the internal structures of the leaf, LSM (laser scanning microscope) observations conducted to confirm the change in the internal structure revealed more than 5% transient change in stomatal size following exposure to one minute to high frequency sound of 10kHz that reverted within ten minutes. Our results demonstrate the potential of laser biospeckle to speedily monitor in vivo response of plants to sound stimuli and thus could be a possible screening tool for selecting appropriate frequency sounds to enhance or delay the activity of plants. (337 words).

Lighting system bioinspired by Haworthia obtusa.

Electricity plays an important role in modern societies, with lighting and illumination accounting for approximately one-fifth of the global demand for electricity. Haworthia obtusa has the remarkable ability to collect solar light through a so-called 'window' which allows it to photosynthesise in the dark. Inspired by this unique characteristic, we developed a novel lighting system that does not use electricity. The 'window' of H. obtusa is replicated using a scattering medium that collects solar light and guides it to an optical fibre. The optical fibre then carries the light indoors, where illumination is needed. The efficacy of this unique lighting system was confirmed both numerically and experimentally. The developed system should help in lowering energy consumption.

Optical characteristics of human skin with hyperpigmentation caused by fluorinated pyrimidine anticancer agent.

The fluorinated pyrimidine anticancer agent has several side effects that degrade the quality of life of patients, including hyperpigmentation. Hyperpigmentation differs in color from common pigmentation such as a suntan, giving rise to dramatic skin appearance changes. In this study, we measured the optical properties of the skin of patients with hyperpigmentation by using the reflection spatial profile method (RSPM). The absorption coefficient in hyperpigmentation increased ~1.5-2.5 times and pheomelanin significantly increased compared to the normal skin. In addition, the scattering coefficient of skin with hyperpigmentation was about 65.9-76.5% of that of normal skin.

Artificial chameleon skin that controls spectral radiation: Development of Chameleon Cool Coating (C3).

Chameleons have a diagnostic thermal protection that enables them to live under various conditions. Our developed special radiative control therefore is inspired by the chameleon thermal protection ability by imitating its two superposed layers as two pigment particles in one coating layer. One particle imitates a chameleon superficial surface for color control (visible light), and another particle imitates a deep surface to reflect solar irradiation, especially in the near-infrared region. Optical modeling allows us to optimally design the particle size and volume fraction. Experimental evaluation shows that the desired spectral reflectance, i.e., low in the VIS region and high in NIR region, can be achieved. Comparison between the measured and calculated reflectances shows that control of the particle size and dispersion/aggregation of particle cloud is important in improving the thermal-protection performance of the coating. Using our developed coating, the interior temperature decreases and the cooling load is reduced while keeping the dark tone of the object.