Light Utilization Rate Research Articles

Photobioreactors for microalgal cultures: A Lagrangian model coupling hydrodynamics and kinetics.

Closed photobioreactors have to be optimized in terms of light utilization and overall photosynthesis rate. A simple model coupling the hydrodynamics and the photosynthesis kinetics has been proposed to analyze the photosynthesis dynamics due to the continuous shuttle of microalgae between dark and lighted zones of the photobioreactor. Microalgal motion has been described according to a stochastic Lagrangian approach adopting the turbulence model suitable for the photobioreactor configuration (single vs. two-phase flows). Effects of light path, biomass concentration, turbulence level and irradiance have been reported in terms of overall photosynthesis rate. Different irradiation strategies (internal, lateral and rounding) and several photobioreactor configurations (flat, tubular, bubble column, airlift) have been investigated. Photobioreactor configurations and the operating conditions to maximize the photosynthesis rate have been pointed out. Results confirmed and explained the common experimental observation that high concentrated cultures are not photoinhibited at high irradiance level.

A Photo-Curing Method to Prepare Biomimetic Micro-Nano Structure of Butterfly Wing Scale

It has been well-known that butterfly wings possess interesting optic properties. Recently, dendritic micro-nanostructure has been found in the wing scales of butterfly Trogonoptera brookiana, which shows excellent light-trapping effect, especially for the visible light. When light enters such a dendritic micro-nanostructure, it will be trapped and eventually absorbed by multiple reflections to generate heat. It is desirable to prepare a biomimetic structure resembling the micro-nanostructure of the butterfly wing scale, which may lead to a new material that can potentially improve the light utilization rate of solar thermal heater and other similar applications. However, a convenient method to make such a structure in large scale is still lacking. Herein, an easy and handy approach has been developed to prepare biomimetic dendritic structure. The starting material is negative photoresist, a chemical reagent which is widely used in photography. A simple device that can adjust the intensity and interval of ultraviolet illumination has been designed and set up. A periodic structure has been achieved via photo-curing with ultraviolet light and the ratio of illumination time has been optimized.

Study on Preparation of a New-Type Catalyst and its Catalytic Activity

To improve the utilization rate of visible light in the degradation of the dye wastewater, the supported mesoporous TiO2 catalyst with perlite as the carrier was prepared. The effect of the calcination time and the loading time on the degradation of the methylene blue by the catalyst was analyzed. The result showed that: as the calcination time exceeded 1.5h, the catalyst activity decreased with the calcination time increasing; under the condition of the optimal calcination time of 1.5h, the degradation rate of methylene blue by visible light reached 71.59%; the multi-loading was in favor of increasing the catalyst activity, of which 3-time loading was the optimal.

The Effect of Chip’s Size on the Performence of GaN-Based LED Chips

Before cutting into a single chip, we have tested LED chips with different sizes that is produced on the some condition. With different drive currents, we compared the luminous intensity and working voltage about the two samples. The results show that: within a certain range, the larger chip is better. Because of low light utilization rate, it isn’t the bigger of chip area the better the performance is. We should choose the best size in application.

Functional traits explain phytoplankton responses to environmental gradients across lakes of the United States

Ecological communities exhibit regular shifts in structure along environmental gradients, but it has proved difficult to dissect the mechanisms by which environmental conditions determine the relative success of species. Functional traits may provide a link between environmental drivers and mechanisms of community membership, but this has not been well tested for phytoplankton, which dominate primary production in many aquatic ecosystems. Here we test whether functional traits of phytoplankton can explain how species respond to gradients of light and phosphorus across U.S. lakes. We find that traits related to light utilization and maximum growth rate can predict species' differential responses to the relative availability of these resources. These results show that laboratory-measured traits are predictive of species' performance under natural conditions, that functional traits provide a mechanistic foundation for community ecology, and that variation in community structure is predictable in spite of the complexity of ecological communities.

Hierarchical ZnO “rod like” architecture synthesized via reverse micellar route for improved photocatalytic activity

Hierarchical ZnO “rod like” architecture was successfully synthesized via reverse micellar route and characterized by various techniques. The FESEM studies show controlled decomposition of zinc oxalate into ZnO “rod like” architecture at 500°C with slow heat rate at 1°/min. Interestingly, improved photocatalytic activity was observed for the degradation of Rhodamine B, due to the self assembly of hexagonal nanoparticles of zinc oxide forming hierarchical ZnO “rod like” architecture which can greatly enhance the light utilization rate due to its special architecture and enlarge the specific surface area, providing more reaction sites and promoting mass transfer. More importantly, the reusability studies of this architecture were most economical.

Hierarchical ZnO nanostructured membrane for multifunctional environmental applications

To counter the global water crisis such as water resources scarcity and water quality deterioration, membrane filtration has been widely used as a promising technology. Recently, nano-materials and its structured membranes demonstrated multifunctional water purification capability in terms of decontamination and disinfection. Here, hierarchical nitrogen (N)-doped “nut-like” ZnO nanostructured material was hydrothermally synthesized at large scale. This hierarchical N-doped “nut-like” ZnO nanostructured material was well characterized and successfully assembled on a piece of polymer membrane surface to create a multifunctional membrane. This newly developed membrane demonstrated high pollutants removal ability via rejection and photodegradation, and strong antibacterial growth ability under visible light irradiation. At the same time, this novel membrane holds the potential to produce clean water at a constant high flux. The experimental results indicated that the hierarchical N-doped ZnO “nut-like” nanostructured material enhanced the photocatalytic activity in a comparison to commercial ZnO powder. This is caused by enlarging the specific surface area and enhancing the light utilization rate. It is reasonable to believe this hierarchical N-doped “nut-like” ZnO nanostructured membrane would benefit the water purification field.

Hierarchical Nitrogen‐Doped Flowerlike ZnO Nanostructure and Its Multifunctional Environmental Applications

Hierarchical nitrogen-doped ZnO flowerlike nanostructures were synthesized on a large scale. These nanostructures were characterized by FESEM, HRTEM, XRD, FTIR, XPS, and TGA, and their suitability for multifunctional environmental applications was investigated. The experimental results demonstrated that the hierarchical N-doped ZnO flowerlike nanostructure enhances the photodegradation of methyl blue (MB) and acid orange 7 (AO7) by presenting a large specific surface area and high light utilization rate, inhibits the growth of bacteria without light irradiation, and increases the permeate flux when used in a membrane filtration system. These advantages of the hierarchical N-doped ZnO flowerlike nanostructure brings benefits to the environmental application fields.

Effect of Juglone from <i>C.cathayensis</i> Exocarp on Summer Peony Photoinhibition

This paper studies the effects of the Juglone on improving the photosynthesis of the peony growing in the summer field, and alleviating the photosynthesis inhibition in the two months of July and August, by using the 0.06mg/L Juglone extracted from the C.cathayensis exocarp, one kind of the forestry waste, to insufflate the peony leaf surface.The research results show that ,by comparing the peony leaf after procession with the control group, the Pn summit values of the photosynthetic rate improve by 10.5% and 12.8% respectively, and the photosynthesis noon-break is greatly shortened; the stomatal conductance variance of the leaf is not big, but the Ci content decreases significantly; the PSII photochemical efficiency of Fv/Fm reduces by 20% and 26% respectively; ΦPSII decreases by 18.1% and 19.9% respectively;between the time period 10 am and 1 pm, when the sunlight is the most sufficient, the contents of the chlorophyll qP decrease by 10% and 11.6% respectively,and the contents of the NPQ increase by 17.3% and 14.3% respectively. The research results show that Juglone could greatly reduce the summer sunlight harm on the photosynthetic system of the peony leaf chloroplast, and improve the light utilization rate of the peony leaf.

Hierarchical CuO/ZnO Membranes for Environmental Applications under the Irradiation of Visible Light

Solar visible light is a source of clean and cheap energy. Herein, a new kind of hierarchical CuO/ZnO nanomaterial was synthesized using a facile process. Characterized by FESEM, TEM, XRD, XPS, and so forth, this CuO/ZnO naomaterial shows a special hierarchical nanostructure with CuO nanoparticles grown on ZnO nanorods. By assembling the hierarchical CuO/ZnO nanomaterials on a piece of commercial glassfiber membrane, a novel hierarchical CuO/ZnO membrane was fabricated. This CuO/ZnO membrane demonstrated excellent environmental applications, such as improved photodegradation of contaminants and antibacterial activity, under the irradiation of visible light. Compared with pure ZnO nanorod membrane, the improved photodegradation and antibacterial capacities of this hierarchical CuO/ZnO membrane result from the special hierarchical nanostructure of CuO/ZnO nanomaterials, which could enhance light utilization rate, enlarge specific surface area, and retard the recombination of electrons and holes at the interfacial between CuO and ZnO. This hierarchical CuO/ZnO membrane is also easy to be regenerated by completely mineralizing the adsorbed contaminants under the irradiation of visible light. All the above characteristics of this hierarchical CuO/ZnO membrane indicate its great potential in environmental applications with solar visible light.

Hierarchical CuO/ZnO “corn-like” architecture for photocatalytic hydrogen generation

Novel high efficient photocatalyst is the key for photocatalytic hydrogen generation from water splitting. In this study, a novel hierarchical CuO/ZnO “corn-like” architecture was designed and synthesized via a combination of hydrothermal and photodeposition method. The as-prepared nanostructured materials was shown to effectively generate hydrogen in the mixture of methanol and water (v/v = 1:10). This is because the hierarchical CuO/ZnO “corn-like” architecture: 1) greatly enhances the light utilization rate due to its special architecture, 2) enlarges the specific surface area, providing more reaction sites and promoting mass transfer, 3) promotes the photogenerated electrons transfer from ZnO to CuO, achieving the anti-recombination effect of electrons and holes, and 4) avoids the photocorrosion of ZnO to improve the stability of ZnO as a catalyst during water splitting. Moreover, the novel hierarchical CuO/ZnO “corn-like” architecture is easily recovered for reuse.

基于折射/全反射/反射/折射结构的LED准直系统的设计

A high efficient,compact,Refractive / Total internal reflection / Reflective / Refractive(RIXR) collimating system was designed and optimized to collect a wide angle range light to emit the collimating beam with a small divergence angle.Firstly,the surface of the initial structure of the system was calculated according to the edge-ray principle and Simultaneous Multiple Surfaces(SMS) method based on the non-imaging optics theory.Then,the initial structure was optimized by using Zemax optical design software.Finally,the best LED collimating system was successfully designed.According to the results of the design,the semi-diameter of the RIXR collimating system is 20 mm,aspect ratio is 0.25 and its collection angle is 200°.These results indicate that the system can completely collect the light emitted by LED sources.As the root mean square radius of a spot diagram for the edge field(± 3.178°)obtained by the reverse ray tracing is less than 2.1 μm,the edge field shows an excellent focusing effect.Furthermore,when the light absorption loss of the material and reflection loss of the interface are fully considered,the light energy utilization rate is as high as 83.48%.Experiments demonstrate that the RIXR-type collimating system has advantages in a compact structure,high light energy utilization ratio and easy to use.

Hierarchical ZnO/Cu “corn-like” materials with high photodegradation and antibacterial capability under visible light

A novel hierarchical ZnO/Cu "corn-like" material was successfully synthesized via facile low temperature hydrothermal and photo-deposition methods. This novel hierarchical material was well characterized by FESEM, XRD, EDS, UV-Vis. This novel material displayed high photodegradation and antibacterial capability under the irradiation of visible light. This is owing to its unique properties, including maximized light utilization rate via red-shifting the light absorption spectrum, enhanced specific surface area for mass transfer and reaction sites, and retarded recombination of photogenerated electrons and holes. Moreover, this novel hierarchical ZnO/Cu "corn-like" material demonstrated easy recovery from treated water for reuse. All these excellent properties indicate that this novel hierarchical ZnO/Cu "corn-like" material has a bright future in water purification applications.

Design of a projector headlamp without using a screen

A design for a projector headlamp that does not use a screen for low-beam lighting is proposed in this paper. The design not only enhances the light source utilization rate but also the elimination of the screen element prevents heat accumulation. The surface of the headlamp reflector is partitioned into six zones and, since there are no steps between reflectors, the zones are smoothly connected. A design equation for the reflector that combines varied lengths for both the circumference and optical axis is proposed and utilized for the surface design of each zone. Thus the reflector has the built-in ability to control light distribution in both the circumference and optical axis directions; consequently, it is able to create a very flexible light pattern, and is able to control all light rays to be below the cut-off line. As a result, the proposed projector headlamp can create a light distribution that meets the low-beam requirements of the ECE R112 standard.

Growth characteristics of microalgae in high-concentration co2 gas, effects of culture medium trace components, and impurities thereon

In order to reduce release of CO2 contained in the flue gas from a power plant, we assumed a system in which the flue gas was directly blown into a pond and CO2 was fixed on microalgae. We have experimentally examined the basic growth characteristics, such as trace components of culture medium, effects of impurities from exhaust gas, and light utilization rate of algal productivity, mainly forNonnochloropsis sp. NANNP-2 from SERI collection. Although Ni and V contained in heavy oil burnt ashes dissolve into culture solution, their concentrations are low, and they have no particular adverse effect on growth as impurities. Culture medium trace component (i.e., heavy metals and vitamins) are essential for the NANNP-2. However, for the PHAEO-2(Phaeodactylum sp.), the growth rate hardly changes, even if vitamins and heavy metals other than Fe are eliminated.