In this paper a self-startup DC-DC boost converter for thermal energy harvesting applications is presented. A startup circuit boosts an internal supply voltage using a low voltage generated from a thermoelectric generator to operate the internal circuitry of the converter. To reduce power dissipation, the startup circuit is disabled after the startup operation is finished. A boosted output voltage is obtained by alternating an auxiliary converter for the internal supply voltage and a main converter for the output voltage. The converter has been implemented in a 0.35 μm complementary metal–oxide–semiconductor (CMOS) process. Measurement results shows that the designed converter is capable of generating an output voltage close to 3V from an input voltage of 200 mV, and can provide a maximum output power of 278 μW with an end-to-end power efficiency of 46.5%. It occupies an active area of 0.36 mm2.

This paper presents a maximum power point tracking (MPPT) interface circuit for low-voltage DC-type energy harvesting sources such as light and thermal energy. Most energy harvesting systems used in miniature-sized sensor systems require start-up circuits because the output voltages of small-sized energy transducers are very low and not enough to directly power electronic systems. The proposed interface circuit is driven directly by the low output voltages of small size energy transducers, eliminating the need for complex start-up circuitry. A simple MPPT controller with the fractional open-circuit voltage (FOCV) method is designed and fabricated in a 65-nm complementary metal oxide semiconductor (CMOS) process. Measurement results show that the designed circuit can track the MPP voltage even in the presence of the open-circuit voltage fluctuations and can operate properly at operating voltages as low as 0.3 V. The interface circuit achieves a peak power efficiency of 97.1% and an MPPT accuracy of over 98.3%.

In the conventional approach widely used for multi-input energy harvesting (MIEH), energy harvesting, energy combining, and power conversion are performed integrally in an inductor sharing block through time multiplexing operations, which is not suitable for hot-pluggable systems. In the MIEH system proposed in this paper, an energy harvesting block (EHB) and a power management block (PMB) are independent of each other to increase the modularity of the system. Therefore, the EHB can be optimized to extract maximum power from energy sources, and the PMB can be focused on combining input energies and converting power effectively. This paper mainly focuses on the design and implementation of the EHB. For light, vibration, and thermal energy, the measured peak power efficiencies of the EHB implemented using a 0.35 μm CMOS process are 95.2%, 92.5%, and 95.5%, respectively. To confirm the functionality and effectiveness of the proposed MIEH system, a PMB composed of simple charge pump circuits and a power management unit has also been implemented and verified with the designed EHB.

For the purpose of determining neurophysiological mechanism of math anxiety, we conducted an EEG measurement for 22 sixth grade elementary students including 11 students with high math anxiety (HMA group), and 11 students with low math anxiety (LMA group). We found that in HMA group, delta wave was significantly generated from the right frontal lobe, and in LMA group, four paths are clearly connected while they perform math tasks (right inferior occipital gyrus ↔ left superior parietal lobule /left middle frontal gyrus ↔ left inferior parietal lobule /left middle frontal gyrus ↔ right inferior parietal lobule /right middle frontal gyrus ↔ right inferior parietal lobule). According to the above results we suggest that math anxiety is related to emotions associated with pain, reduces working memory and has a negative effect on math performance

The production of two kinds of catalase-peroxidase, viz. catalase-2 and catalase-3 of Deinococcus radiophilus varied depending upon growth phases and oxidative stress. A gradual increase in total catalase activity occurred during exponential and stationary phase. Electrophoretic resolution of these catalases in Deinococcal cell extracts revealed the uniform occurrence of catalase-2 and the appearance of catalase-3 only during the late exponential and stationary phase. A substantial increase in total catalase was observed in either hydrogen peroxide- or UV-treated cells. Monitoring of D. radiophilus catalase activity in the oxidative stressed and non-treated cells by gel electrophoresis followed by densitometry revealed the several-fold increase in catalase-3, which is above the constant level of catalase-2. The occurrence of catalase-3 and catalase-2 revealed by fractionation of sucrose-shocked cells suggests that catalase-3 is a cytosolic inducible enzyme whereas catalase-2 is the membrane-associated constitutive enzyme.