Naphthalene (Nap) and methylnaphthalene (MN) are the most abundant polycyclic aromatic hydrocarbons (PAHs) in atmosphere and have been proposed to be important precursors of anthropogenic secondary organic aerosol (SOA) derived from laboratory chamber experiments. In this study, atmospheric Nap/MN and their gas-phase photooxidation products were quantified by a Proton Transfer Reaction-Quadrupole interface Time-of-Flight Mass Spectrometer (PTR-QiTOF) during the 2016 winter in Beijing. Phthalic anhydride, a late generation product from Nap under high-NOx conditions, appeared to be more prominent than 2-formylcinnamaldehyde (early generation product), possibly due to more sufficient oxidation during the haze. 1,2-Phthalic acid (1,2-PhA), the hydrated form of phthalic anhydride, was capable of partitioning into aerosol phase and served as a tracer to explore the contribution of Nap to ambient SOA. The measured fraction in particle phase (Fp) of 1,2-PhA averaged at 73 ± 13% with OA mass loadings of 52.5–87.8 μg/m3, lower than the value predicted by the absorptive partitioning model (100%). Using tracer product-based and precursor consumption-based methods, 2-ring PAHs (Nap and MN) were estimated to produce 14.9% (an upper limit) of the SOA formed in the afternoon during the wintertime haze, suggesting a comparable contribution of Nap and MN with monocyclic-aromatics on urban SOA formation.
Triboelectric nanogenerator (TENG) harvesting living environmental energy has been demonstrated to be a potential energy source for internet of things, for its unique properties, such as high-output performance, clean, sustainability, low-cost etc., which have resulted in an explosive growth of related research in the past several years. However, due to the unique features of electrical output signals of TENGs like the pulsed output with random amplitude and frequency, ultra-high voltages and impedance, the electrical power generated by TENGs is hard to be delivered to the load efficiently or stored directly by the classical power management methods. Meanwhile, the mechanical energy from the environment is time dependent, unstable and sometime unpredictable, but the power required to drive electronics is regulated with a fixed input voltage and power. So it is important to store the generated energy in a battery or capacitor, so that it can be used to power a device sustainably. Fortunately, both the power management and energy storage for TENG have obtained significantly progress recently. Here, this paper reviews the progress made in power management and storage, including theoretical development, charge boosting, buck converting, energy storage, and the new enabled applications, aiming at building a self-charging power unit (SCPU) that can be a standard power package for sustainable operation of an electronic device. Finally, we will give an outlook for future development of applying SCPU for internet of things.
A process of fabricating a seven layer microfluidic chip using CO2 laser processing and hot bonding technology is presented. The applied polymer substrates were poly(methyl-methacrylate) (PMMA), polycarbonate (PC), polystyrene (PS) and polyethylene terephthalate (PET). The results show the optimal combination of polymer substrates for the seven layer microfluidic chip at the hot bonding parameters of bonding temperature of 100 degrees C and bonding pressure of 1 MPa for maintaining times of nine minutes. Due to the different properties of the polymer substrates, the profile of the microchannel in the different polymer sheets for the same CO2 laser processing parameters. The maximum tensile strength of the microfluidic was measured as 1.0 MPa. The combined polymers with the minimum binding force were PC and PMMA. At the end, a mixing experiment was performed in the seven layer microfluidic chip with different fluid Re numbers.