Easy Fabrication of Performant SWCNT-Si Photodetector

We propose a simple method to fabricate a photodetector based on the carbon nanotube/silicon nitride/silicon (CNT/Si3N4/Si) heterojunction. The device is obtained by depositing a freestanding single-wall carbon nanotube (SWCNT) film on a silicon substrate using a dry transfer technique. The SWCNT/Si3N4/Si heterojunction is formed without the thermal stress of chemical vapor deposition used for the growth of CNTs in other approaches. The CNT film works as a transparent charge collecting electrode and guarantees a uniform photocurrent across the sensitive area of the device. The obtained photodetector shows a great photocurrent that increases linearly with the incident light intensity and grows with the increasing wavelength in the visible range. The external quantum efficiency is independent of the light intensity and increases with the wavelength, reaching 65% at 640 nm.

All organic multiferroic magnetoelectric complexes with strong interfacial spin-dipole interaction

The organic magnetoelectric complexes are beneficial for the development on flexible magnetoelectric devices in the future. In this work, we fabricated all organic multiferroic ferromagnetic/ferroelectric complexes to study magnetoelectric coupling at room temperature. Under the stimulus of external magnetic field, the localization of charge inside organic ferromagnets will be enhanced to affect spin–dipole interaction at organic multiferroic interfaces, where overall ferroelectric polarization is tuned to present an organic magnetoelectric coupling. Moreover, the magnetoelectric coupling of the organic ferromagnetic/ferroelectric complex is tightly dependent on incident light intensity. Decreasing light intensity, the dominated interfacial interaction will switch from spin–dipole to dipole–dipole interaction, which leads to the magnetoelectric coefficient changing from positive to negative in organic multiferroic magnetoelectric complexes.

A Model for the Digital Method of Measuring LED Incident Photocurrent

Pulse oximeters and other light based sensor types are used to monitor arterial blood oxygen levels, heart rate, and much more that rely on LEDs and photodiodes. The conventional method of using photodiodes to detect light signals is accurate, but requires relatively expensive hardware processing to extract the signal. Digital sensing of light using an LED provides a low-cost alternative by using a voltage threshold timing method. However, the accuracy of this method is dependant on the microcontroller clock speed and suffers from variable sample rate (100 us to 10 ms). This paper develops a model for a digital light sensing method using only a microcontroller’s ADC and timer, and an LED. Using the voltage discharge curve of a reverse biased LED, the sensor is capable of accurately detecting light intensities ranging from 0–3885 mcd at a sample period of 500 us. A linear relationship was found through the incident light intensity ranges of 0 to 3880 mcd. The model fit the expected experimental values, with an estimated photocurrent ranging from 10 pA to 55 nA. With an R2 of 0.9997, the model demonstrates the digital sensing method linearly responds to incident light intensity and can simplify the design of pulse oximeters and similar light based sensor types.

How Do Operational and Design Parameters Effect Biomass Productivity in a Flat-Panel Photo-Bioreactor? A Computational Analysis

Optimal production of microalgae in photo-bioreactors (PBRs) largely depends on the amount of light intensity received by individual algal cells, which is affected by several operational and design factors. A key question is: which process parameters have the highest potential for the optimization of biomass productivity? This can be analyzed by simulating the complex interplay of PBR design, hydrodynamics, dynamic light exposure, and growth of algal cells. A workflow was established comprising the simulation of hydrodynamics in a flat-panel PBR using computational fluid dynamics, calculation of light irradiation inside the PBR, tracing the light exposure of individual cells over time, and calculation the algal growth and biomass productivity based on this light exposure. Different PBR designs leading to different flow profiles were compared, and operational parameters such as air inlet flowrate, microalgal concentration, and incident light intensity were varied to investigate their effect on PBR productivity. The design of internal structures and lighting had a significant effect on biomass productivity, whereas air inlet flowrate had a minimal effect. Microalgal concentration and incident light intensity controlled the amount of light intensity inside the PBR, thereby significantly affecting the overall productivity. For detailed quantitative insight into these dependencies, better parameterization of algal growth models is required.

A renewable photocatalytic system with dramatic photocatalytic activity for H2 evolution and constant light energy utilization: Eosin Y sensitized ZnWO4 nanoplates loaded with CuO nanoparticles

It is necessary for the commercialization of sunlight-driven H2 evolution to develop an efficient photocatalytic system whose energy utilization is independent on incident light intensity. Unfortunately, limited attention has been...

Temperature and Light-Quality-Dependent Regulation of Freezing Tolerance in Barley

It is established that, besides the cold, incident light also has a crucial role in the cold acclimation process. To elucidate the interaction between these two external hardening factors, barley plantlets were grown under different light conditions with low, normal, and high light intensities at 5 and 15 °C. The expression of the HvCBF14 gene and two well-characterized members of the C-repeat binding factor (CBF)-regulon HvCOR14b and HvDHN5 were studied. In general, the expression level of the studied genes was several fold higher at 5 °C than that at 15 °C independently of the applied light intensity or the spectra. The complementary far-red (FR) illumination induced the expression of HvCBF14 and also its target gene HvCOR14b at both temperatures. However, this supplementation did not affect significantly the expression of HvDHN5. To test the physiological effects of these changes in environmental conditions, freezing tests were also performed. In all the cases, we found that the reduced R:FR ratio increased the frost tolerance of barley at every incident light intensity. These results show that the combined effects of cold, light intensity, and the modification of the R:FR light ratio can greatly influence the gene expression pattern of the plants, which can result in increased plant frost tolerance.

Effect of Delays on the Response of Microalgae When Exposed to Dynamic Environmental Conditions

During mathematical representation of microbial cultures, it is normally assumed that changes in the environment produce instantaneous effects on growth. However, reports are available indicating that sometimes this may not be the case. This work studied the existence of delays on the response of a population of microalgae when subjected to changes in energy and carbon sources, and when exposed to a growth inhibitor. Results show that no appreciable delays exist when microalgae undergo changes in the incident light intensity. For changes in carbon source concentration (inorganic carbon), a small delay in the range of minutes was detected. Finally, when exposing microalgae to inhibitory concentrations of ammonia, a significant delay of several hours was observed.