Random and Diblock Thermoresponsive Oligo(ethylene glycol)-Based Copolymers Synthesized via Photo-Induced RAFT Polymerization

Amphiphilic random and diblock thermoresponsive oligo(ethylene glycol)-based (co)polymers were synthesized via photoiniferter polymerization under visible light using trithiocarbonate as a chain transfer agent. The effect of solvent, light intensity and wavelength on the rate of the process was investigated. It was shown that blue and green LED light could initiate RAFT polymerization of macromonomers without an exogenous initiator at room temperature, giving bottlebrush polymers with low dispersity at sufficiently high conversions achieved in 1–2 h. The pseudo-living mechanism of polymerization and high chain-end fidelity were confirmed by successful chain extension. Thermoresponsive properties of the copolymers in aqueous solutions were studied via turbidimetry and laser light scattering. Random copolymers of methoxy- and alkoxy oligo(ethylene glycol) methacrylates of a specified length formed unimolecular micelles in water with a hydrophobic core consisting of a polymer backbone and alkyl groups and a hydrophilic oligo(ethylene glycol) shell. In contrast, the diblock copolymer formed huge multimolecular micelles.

Visible Light-Controlled Living Cationic Polymerization of Methoxystyrene

Photo-controlled living polymerization has received great attention in recent years. However, despite the great success therein, the report on photo-controlled living cationic polymerization has been greatly limited. We demonstrate here a novel decolorable, metal-free and visible light-controlled living cationic polymerization system by using tris(2,4-dimethoxyphenyl)methylium tetrafluoroborate as the photocatalyst and phosphate as the chain transfer agent (CTA) for polymerization of 4-methoxystyrene. This polymerization reaction under green LED light irradiation shows clear living characteristics including predictable molar mass, narrow molar-mass dispersity (Đ = 1.25), and sequential polymerization capability. In addition, the photocata-lytic system exits excellent “on-off” photo switchability and shows the longest “off period” of 36 h up to now for photo-controlled cationic polymerization. Furthermore, the residual photo-catalyst is easily deactivated and decolored with addition of a base after the polymerization.

Visible Light-Controlled Living Cationic Polymerization of Methoxystyrene

Photo-controlled living polymerization has received great attention in recent years. However, despite the great success therein, the report on photo-controlled living cationic polymerization has been greatly limited. We demonstrate here a novel decolorable, metal-free and visible light-controlled living cationic polymerization system by using tris(2,4-dimethoxyphenyl)methylium tetrafluoroborate as the photocatalyst and phosphate as the chain transfer agent (CTA) for polymerization of 4-methoxystyrene. This polymerization reaction under green LED light irradiation shows clear living characteristics including predictable molar mass, narrow molar-mass dispersity (Đ = 1.25), and sequential polymerization capability. In addition, the photocata-lytic system exits excellent “on-off” photo switchability and shows the longest “off period” of 36 h up to now for photo-controlled cationic polymerization. Furthermore, the residual photo-catalyst is easily deactivated and decolored with addition of a base after the polymerization.

The effect of white and green LED-lights on the catch efficiency of the Barents Sea snow crab (Chionoecetes opilio) pot fishery

In commercial snow crab (Chionoecetes opilio) fishery, the catch efficiency of the conical pots is important for increasing the profitability of the industry. This study evaluated the effect of adding green and white light emitting diodes (LED) on the catch efficiency of commercially used conical pots. The results from the field experiments showed that inserting artificial lights significantly increases the catch efficiency for snow crab over the minimum landing size of 95 mm carapace width of up to 76% when using green LED, and by 52–53% on average when using white LED. This study shows that it is possible to improve the catch efficiency of the snow crab fishery by applying artificial LED lights to the conical snow crab pots, potentially resulting in an important economic benefit to the snow crab fishery.

RFID-Based Digital Door Locking System

This is an IoT-enabled RFID-based door locking gadget. This door lock system will know how long the door is open and in this door lock system, only those people who register will be able to enter using their card. It uses a servo motor that operates with the help of Arduino. The Arduino board runs with complete programming that is stored inside it. By using this gadget, an owner can track his office and the place where he wants to let the specific people in. It is also very secure. RFID Module, LCD Display Red and Green and Yellow LED Light and Buzzer have also been used in this door lock system. When the door is locked, the yellow LED will be on and when the door lock is open, the green led light will turn on. The Red LED work will alert you that your card is wrong.

RFID-Based Digital Door Locking System

This is an IoT-enabled RFID-based door locking gadget. This door lock system will know how long the door is open and in this door lock system, only those people who register will be able to enter using their card. It uses a servo motor that operates with the help of Arduino. The Arduino board runs with complete programming that is stored inside it. By using this gadget, an owner can track his office and the place where he wants to let the specific people in. It is also very secure. RFID Module, LCD Display Red and Green and Yellow LED Light and Buzzer have also been used in this door lock system. When the door is locked, the yellow LED will be on and when the door lock is open, the green led light will turn on. The Red LED work will alert you that your card is wrong.

Carrier Dynamics in InGaN/GaN-Based Green LED under Different Excitation Sources

The excitation power and temperature dependence of the photoluminescence (PL) and electroluminescence (EL) spectra were studied in green InGaN/GaN multiple quantum well (MQW)-based light-emitting diodes (LED). An examination of the PL-325, PL-405, and EL spectra at identical optical or electrical generation rates at room temperature showed that the normalized spectra exhibited different characteristic peaks. In addition, the temperature behavior of the peak energy was S-shaped for the PL-405 spectrum, while it was V-shaped for the EL spectrum. These measurement results demonstrate that the excitation source can affect the carrier dynamics about the generation (injection), transfer, and distribution of carriers.

Methods of Measuring Radiation Spectra in a Laboratory Workshop on Physics and Research

The authors single out the formation of research skills as one of the most important aspects of teaching students of higher educational institutions in the areas of engineering and technical profile. As part of a laboratory workshop in physics, students acquire professional skills in research and technological fields. In this paper, we consider the method of measuring the radiation spectra of various light sources, which the authors propose to use when setting up laboratory work in physics. The conditions of the experiment are described and the scheme of the working installation is given. Measurements of the radiation spectra are carried out using a monochromator and a photodetector pre-graded in terms of transmission and spectral sensitivity.Examples of the emission spectra of a green LED, a red semiconductor laser and a fluorescent lamp measured by the considered method are given. Recommendations of such experiments are given when conducting laboratory work and research work of students. The proposed method of performing laboratory research will help students acquire skills in working with spectral measuring equipment, teach them not only to measure and build the emission spectra of light sources, but also to calculate the spectral width of the gap at which the spectra were measured and to estimate measurement errors.

LED Colour Trap for Aedes aegypti Control

Background: Aedes aegypti mosquitoes transmit dengue, zika, and chikungunya viruses, neglected diseases that are considered global health challenges. Due to the lack of antiviral drugs and vaccines for these illnesses, vector control with chemical insecticides is the principal strategy for preventing their spread. However, vector populations are becoming increasingly resistant to insecticides, and the development of other control measures is therefore imperative. Methods: A new insect trap (IT) was used to control Aedes aegypti. A specific light-emitting diode (LED) served as the attractant based on specific wavelength ranges (450-495, 500-550 and 570-600 nm). The IT utilized insect-attracting and killing mechanisms that included a black capture box, a suction-producing mechanism, an electric shock device and a nylon cloth device that held surviving mosquitoes, which thus died by starvation. Capture assays of twenty non-feeding females inside a cage were performed in triplicate using different LED intensities. A commercial trap (ultraviolet lamp attractant and suction system) was used as a positive control. Results: Capture assays of A. aegypti with different intensities and LED combinations showed that the tricolored trap captured 100% of the females, followed by the Green LED 8 set, which captured 91%; in comparison, commercial traps captured approximately 25% of the insects. Although there were no significant differences between the experimental groups, the tricolored trap probably will capture more mosquito females considering the vision variation in individual females. Conclusion: We herein present a green technology-based IT that is effective, safe and successful for reducing mosquito populations, thereby preventing mosquito-borne disease spread.