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A solar street lamp is a lamp technology that utilizes solar cell to obtain electrical energy during the daylight hour by solar radiation and then use the electrical energy to provide light at night. Semiintegrated lamp tries to overcome complicated installation and expensive price of normally solar street lamp. Semi-integrated solar street lamp only integrated solar cell, controller, and battery, while lamp is separated using cable. This configuration makes semi-integrated lamp cheaper and easier for installation that is suitable for rural area. Therefore, in this paper we develop semi-integrated type of solar street lamp. The illumination of semi-integrated lamp was measured using lux meter. The power of the lamp was calculated to meet the energy needs for 12 hours. The results show that the semi-integrated solar street lamp with low power LED ~2W has been successfully developed. The solar lamp can be automatically turned on for around 12 hours, from 5:50 PM to 5:31 AM (UTC+7). The illumination average of the lamp is 17.42 lux with 6.97 lux deviation. The measurement result of illumination shows that the solar street lamp has maximum distance of more than 140 cm with 230 cm high of lamp.

This paper present simple and inexpensive solar charge controller (SCC) using 8-bit microcontroller ATtiny85. The SCC using a pulse width modulation (PWM) signal to transistor and MOSFET to control current that generated by the microcontroller. The battery voltage state also monitored using a series resistor paralleled to the battery and the voltage drop connected to the microcontroller. The design of SCC consists of 3 major part i.e. microcontroller, current driver, voltage sensing. The purpose of measurement is to know the characteristics of 2 charging modes, mode 1 (one) and mode 2 (two), that occur in the system created. The measured data is the battery voltage as independent variable, and the solar panel’s voltage, the current that flow towards battery and the power provided for charging. Measurements are conducted from the battery voltage state of 7.84 V to 8.4 V. The results show that the solar charge controller using 8-bit microcontroller ATtiny85 was successfully managed to provide current and voltage according to expected design with 400 mA, 8.9 V for the first charging case and 150 mA, 12 V for the second charging case.

Today, institutions of higher education play increasingly active roles in helping achieve a sustainable society. This study aims to demonstrate the lessons learned in the development of a green environment at the Faculty of Engineering, University of Indonesia. This paper reviews the development of the necessary supporting infrastructure and discusses opportunities and challenges in establishing a green environment. The availability and condition of groundwater sources are identified, and the process by which canteen wastewater is treated by phytoremediation is described. Additionally, composting and recycling of solid wastes are encouraged in communities, and a model for an energy-efficient classroom is discussed. Three lessons learned are discussed: a focus on defining the program, continuous education and monitoring, and sources of funding. The implications of this study for relevant practices are also identified.

Abstract Silicon field-effect transistors have now reached gate lengths of only a few tens of nanometers, containing a countable number of dopants in the channel. Such technological trend brought us to a research stage on devices working with one or a few dopant atoms. In this work, we review our most recent studies on key atom devices with fundamental structures of silicon-on-insulator MOSFETs, such as single-dopant transistors, preliminary memory devices, single-electron turnstile devices and photonic devices, in which electron tunneling mediated by single dopant atoms is the essential transport mechanism. Furthermore, observation of individual dopant potential in the channel by Kelvin probe force microscopy is also presented. These results may pave the way for the development of a new device technology, i.e., single-dopant atom electronics.

Summary: Efficiency of a dye‐sensitized solar cell (DSSC) device depends on its semiconductor layer and the sensitizing dye to absorb the light. This work seeks to obtain the best solvent for the natural dye extraction from Melastoma malabathricum L. seeds. The extracted dye is used as sensitizer on TiO2 nanoparticles produced via hydrothermal but optimized at relatively low temperature. Infrared characterization of the extracted dyes showed differences in functional groups using different solvents, whereas ultraviolet visible examination of the dyes showed differences in intensity along the spectrum ranges of 600 to 400 nm with maximum absorption around 550 to 500 nm. Thermal analysis revealed that the natural dye should be stable around room temperature. Analysis on the synthesized TiO2 nanoparticles showed that the average crystallite size reported in the previous work is consistent with crystallite sizes observed in the transmission electron microscope images. Photoactivity examination showed that the DSSC sensitized using natural dye extracted with ethanol containing 20% distilled water on TiO2 synthesized at 150°C has an efficiency of 5.7%, whereas the one on commercial TiO2 P25 Degussa has an efficiency of 3.0%. The DSSC device sensitized using commercial dye on TiO2 synthesized at 150°C has an efficiency of 4.4%, whereas the one on TiO2 P25 Degussa has an efficiency of 4.0%. This result is promising for further development of the DSSC device using TiO2 nanoparticles synthesized at low hydrothermal temperature and sensitized with the natural dye. [ABSTRACT FROM AUTHOR]

Polymerization of composite resins could be affected by iradiance levels of light curing units. Furthermore, imperfect polymerization of resin composite polymerization could cause low surface hardness and high cytotoxicity. This study examined the effect of the irradiance levels of the light curing units on the microhardness of cured resin composites and their cytotoxicity A pulse-lighting curing unit with irradiance levels of 800, 900 and 1,000 mW/cm2 in either 10 or 20 sec was employed for this study and a commercially available continuous-lighting curing unit of 900 mW/cm2 in 20 sec was used as comparison. Resin composite specimens were irradiated using the curing units, and the microhardness with Knoop system and cytotoxicity by the MTT were subsequently determined. The irradiance of 900±10 mW/m2 cm2 emitted from the pulse lighting is the closest value to that emitted by the continuous-lighting curing unit. The resin composites irradiated at higher irradiance levels exhibited significantly higher (p<0.05) microhardness than those irradiated at lower irradiance levels. Regarding their cytotoxicity values, higher significant differences (p<0.05) were observed with increasing irradiance levels. Increased irradiance of the pulse-lighting curing unit raised the level of microhardness while minimizing the cytotoxicity of the tested resin composites. For clinical work, enough microhardness and cytotoxicity values obtained from the resin composites irradiated using the pulse lighting curing unit might provide a safe tooth condition. [ABSTRACT FROM AUTHOR]

In this study, vertically aligned zinc oxide (ZnO) nanorod (NR) arrays were grown with the 2- step method. Spin coating was used to apply the seed layer, and by increasing the number of repetitions (n), higher thickness of the seed layer was achieved. The effects of different seed layer thicknesses, spin coated at different rotational speeds (v) and how the variables (v and n) influence the morphological and crystal properties of the resulting ZnO NRs were analyzed. The effects of 1, 3, and 5 (n), with (v) of 3000 or 4000 rpm were investigated, and the formed seed layers were characterized by using scanning electron microscopy (SEM) and X-ray diffraction (XRD) profiles. The ZnO NR arrays were grown by a chemical bath deposition method because of its simplicity and ease of use. Full width at half maximum (FWHM) analysis was conducted on the XRD chart and Raman spectrum to analyze the grain size and Wurtzite distortion of the ZnO NRs. A lower FWHM value was attributed to the lower number of structural disorders in the ZnO NRs, which equated to the most stable or structured Wurtzite structures in the ZnO NRs, achieved at the lowest FWHM value. The lowest FWHM for (002) XRD peak was obtained at 0.35° for ZnO NRs grown with a seed layer spin coated at 4000 rpm once. The crystallite size calculated by Scherrer's equation gave a size of 25.14 nm. The lowest FWHM for E2(High) Raman peak was obtained at 6.00 cm-1 for ZnO NRs grown with a seed layer spin coated at 4000 rpm three times. [ABSTRACT FROM AUTHOR]

Faced with ever-shrinking reserves of fossil-based energy, in addition to the damaging impacts of the use of fossil-based energy sources, such as the greenhouse effect and global warming, efforts are needed to find energy alternatives. Currently under development as an alternative source of renewable energy, utilizing solar energy as its source, is a device incorporating the dyesensitized solar cell (DSSC), which works using the simple photosynthetic-electrochemical principle at the molecular level. In this type of device, inorganic oxide semiconductors such as titanium dioxide (TiO2) offer great potential for the absorption of photon energy from the solar energy source, especially in the form of a TiO2 nanoparticle structure. In this study, a commercial TiO2 nanoparticle was used. The as-received TiO2 nanoparticle was characterized using X-ray diffraction (XRD) and a scanning electron microscope (SEM). For sensitizer, a natural dye extracted from mangosteen (Garcinia mangostana L.) pericarps was used. The extracted natural dye was characterized using Fourier transform infrared (FTIR) for the functional groups, whereas ultraviolet-visible (UV-Vis) was used to examine the absorption activity of the extracted natural dye. Performance of the DSSC was analyzed through a precision current versus potential difference (I-V) curve analyzer. The maximum power conversion efficiency (PCE) of the mangosteen natural dye was obtained using ethanol containing 20% distilled water as compared to commercial organic dye with a PCE of 4.02%. This result is convincing and promising for the next development. [ABSTRACT FROM AUTHOR]

Resonance frequency shift of a zinc oxide- (ZnO-) functionalized microcantilever as a response to carbon monoxide (CO) gas has been investigated. Here, ZnO microrods were grown on the microcantilever surface by a hydrothermal method. The measurement of resonance frequency of the microcantilever vibrations due to the gas was carried out in two conditions, that is, gas flow with and without air pumping into an experiment chamber. The results show that the resonance frequency of the ZnO-functionalized microcantilever decreases because of CO in air pumping condition, while it increases when CO is introduced without air pumping. Such change in the resonance frequency is influenced by water vapor condition, and a possible model based on water-CO combination was proposed. [ABSTRACT FROM AUTHOR]