The Effect of Radiative Cooling on Reducing the Temperature of Greenhouses.

Currently, greenhouses are widely used for the cultivation of various crops. However, in tropical and subtropical regions, undesired near-infrared radiation (NIR) causes heat loads inside the greenhouse. Recent works have demonstrated that radiative cooling, releasing energy via radiative heat exchange where the heat is dumped directly into outer space, can be achieved by using silica particles designed to emit in the infrared atmospheric transparency window. The purpose of this study is to improve the plastic greenhouse cladding to regulate the temperature inside the greenhouse, mainly by passive cooling. Low-density-polyethylene (LDPE)-based formulations with anti-fogging agent, UV stabilizer, and silica particles were prepared by the melt blending technique and were formed into a double film by extrusion molding. Experimental results showed that under 35 °C ambient conditions, the inner temperature of the simulated greenhouse with the newly developed cladding was 4 to 5 °C less than that of the greenhouse with the commercial agricultural polyethylene (PE) film.

Design of a single-cell positioning controller using electroosmotic flow and image processing.

The objective of the current research was not only to provide a fast and automatic positioning platform for single cells, but also improved biomolecular manipulation techniques. In this study, an automatic platform for cell positioning using electroosmotic flow and image processing technology was designed. The platform was developed using a PCI image acquisition interface card for capturing images from a microscope and then transferring them to a computer using human-machine interface software. This software was designed by the Laboratory Virtual Instrument Engineering Workbench, a graphical language for finding cell positions and viewing the driving trace, and the fuzzy logic method for controlling the voltage or time of an electric field. After experiments on real human leukemic cells (U-937), the success of the cell positioning rate achieved by controlling the voltage factor reaches 100% within 5 s. A greater precision is obtained when controlling the time factor, whereby the success rate reaches 100% within 28 s. Advantages in both high speed and high precision are attained if these two voltage and time control methods are combined. The control speed with the combined method is about 5.18 times greater than that achieved by the time method, and the control precision with the combined method is more than five times greater than that achieved by the voltage method.

Evaluation of the correlation between focal adhesion kinase phosphorylation and cell adhesion force using "DEP" technology.

Dielectrophoresis (DEP) is the phenomenon in which a particle, such as a living cell, is polarized and moved by electrical gravity in a non-uniform electric field. In the present study, the DEP force is utilized to act on the cells to induce spatial movement for investigating the correlation between the cell adhesion force and activation level of focal adhesion kinase (FAK). The DEP force produced by the non-uniform electric field was used to measure the cell adhesion force of ECV304 cells, on type 1 collagen (COL1)- and fibronectin (FN)-coated polydimethylsiloxane (PDMS) membranes. For COL1-coating, ECV304 cells revealed weak and variable adhesion force (0.343-0.760 nN) in the first eight hours of incubation. Interestingly, the cell adhesion force of ECV304 at two and five hours of cultivation was significantly high and matched their FAK activation level. In comparison, ECV304 on FN-coated membrane had higher and more stable cell adhesion force (0.577-2.053 nN). FN coating intensified the cell adhesion force of ECV304 with culture time and similar outcome was present on the activation level of FAK. Therefore, this study demonstrated a relationship between cell adhesion force and FAK activation level that was dependent on the choice of the extracellular matrix (ECM) component. Subsequently, two tyrosine kinase inhibitors (AG18 and genistein) and one PI3K inhibitor (LY294002) were applied to study the influence of protein phosphorylation on the cell adhesion force. FAK plays an important role on cell attachment and DEP force measurement is a useful technique for studying cell adhesion.

Development of an integrated chip for automatic tracking and positioning manipulation for single cell lysis.

This study adopted a microelectromechanical fabrication process to design a chip integrated with electroosmotic flow and dielectrophoresis force for single cell lysis. Human histiocytic lymphoma U937 cells were driven rapidly by electroosmotic flow and precisely moved to a specific area for cell lysis. By varying the frequency of AC power, 15 V AC at 1 MHz of frequency configuration achieved 100% cell lysing at the specific area. The integrated chip could successfully manipulate single cells to a specific position and lysis. The overall successful rate of cell tracking, positioning, and cell lysis is 80%. The average speed of cell driving was 17.74 µm/s. This technique will be developed for DNA extraction in biomolecular detection. It can simplify pre-treatment procedures for biotechnological analysis of samples.

Stable trapping and manually controlled rotation of an asymmetric or birefringent microparticle using dual-mode split-beam optical tweezers.

Inserting a coverslip into half of a Gaussian laser beam at a suitable tilting angle can make the single-mode laser beam become closely spaced dual light spots at the laser focus. In this way, we can reform the conventional single-beam optical tweezers easily and construct a set of dual-mode split-beam optical tweezers, which can be used to manually rotate a trapped and twisted red blood cell around the optical axis. Furthermore, we demonstrate that the split-beam optical tweezers can also stably trap and orient a birefringent polystyrene micro strip particle, which otherwise will self rotate at a varying speed along the structural principal axes, fast spin about the optical axis in a tilting pose, or precess like a gyroscope, in the original linearly polarized single-beam optical tweezers.

Nanoscale surface electrical properties of zinc oxide films investigated by conducting atomic force microscopy.

In this study, conducting atomic force microscopy was employed to investigate the nanoscale surface electrical properties of zinc oxide (ZnO) films prepared by pulsed laser deposition (PLD) at different substrate temperatures for use as anode materials in polymer light-emitting diodes. The results show that the surface conductivity distribution of ZnO is related to its surface structure. At substrate temperatures of 150-200 degrees C, the conducting regions may cover over 90% of the ZnO thin-film surface, thus providing the best local conductivity. Moreover, heating at substrate temperatures of above 250 degrees C can effectively make the conductivity on the ZnO surface uniform. In particular, at substrate temperatures of around 300 degrees C, the conducting regions where currents are between 1 and 2 muA may cover as much as 83% of the surface, and furthermore, the transmission ratio in the visible range is higher than 80%. This is a rather ideal production temperature for the PLD for ZnO films.