The development of eco-friendly flame retardants is crucial due to the hazardous properties of most conventional flame retardants. Herein, adenosine triphosphate (ATP) is reported to be a highly efficient "all-in-one" green flame retardant as it consists of three essential groups, which lead to the formation of char with extreme intumescence, namely, three phosphate groups, providing an acid source; one ribose sugar, working as a char source; and one adenine, acting as a blowing agent. Polyurethane foam was used as a model flammable material to demonstrate the exceptional flame retardancy of ATP. The direct flammability tests have clearly shown that the ATP-coated polyurethane (PU) foam almost did not burn upon exposure to the torch flame. Importantly, ATP exhibits an extreme volume increase, whereas general phosphorus-based flame retardants show a negligible increase in volume. The PU foam coated with 30 wt % of ATP (PU-ATP 30 wt %) exhibits a significant reduction in the peak heat release rate (94.3%) with a significant increase in the ignition time, compared to bare PU. In addition, PU-ATP 30 wt % exhibits a high limiting oxygen index (LOI) value of 31% and HF-1 rating in the UL94 horizontal burning foamed material test. Additionally, we demonstrated that ATP's flame retardancy is sufficient for other types of matrices such as cotton, as confirmed from the results of the standardized ASTM D6413 test; cotton-ATP 30 wt % exhibits an LOI value of 32% and passes the vertical flame test. These results strongly suggest that ATP has great potential to be used as an "all-in-one" green flame retardant.
In this paper, the design and characteristics of a novel ultrasonic motor which is applicable to optical zoom or auto focusing operation of lens system for mobile phone are investigated. Its design and simulation of performances are carried out by FEM (Finite Element Method) commercial software. The shape of the motor is like square without one side, which is able to insert optical lens. Two sheets of piezoelectric ceramic are fixed to both sides of the two legs of an elastic body, respectively. To drive the ultrasonic motor, the voltage is applied to the two sheets of piezoelectric ceramic bonded to one leg. The rotation direction can be easily changed by switching the applied voltage to the piezoelectric sheets bonded to the other legs. The proto type of motor is fabricated and its outer size is 10*10*2 mm3 including the camera lens of which the diameter is 7.5 mm. Its power consumption is about 0.3 W and the rotation speed is adjustable from 10 to 200 rpm according to the applied voltage.
Considering that fire safety is a persistent problem for most polymeric materials, including polyurethane (PU) foam, the demand for flame retardants (FRs) is growing. However, the use of conventional FRs containing halogenated and brominated chemicals has been continuously regulated owing to their toxicity. Here, we demonstrate the layer-by-layer (LbL) coating of negatively charged adenosine triphosphate (ATP) and positively charged chitosan (CS) as the synergistic FR on PU foam, a model flammable polymer material. The FR performance of the PU coated with LbL-assembled ATP and CS (ATP/CS-PU) was tested, and the results suggested that the ATP/CS layers were finely deposited on the surface of the PU without damaging the structure. Only five bilayers (5BL) were sufficient to impart excellent fire retardancy, which exhibited a limiting oxygen index value of 35% and the HF-1 rating in the UL94 foamed material horizontal burning test. In addition, ATP/CS(5BL)-PU showed a significant reduction in the peak heat release rate of 42.0% and in the total smoke release of 30.6% compared to that of bare PU (b-PU). Furthermore, the ATP/CS coatings did not deteriorate the mechanical properties of b-PU. Finally, combined thermogravimetry-Fourier transform infrared spectroscopy (TG-FTIR) showed that ATP/CS(5BL)-PU was safe because it suppresses hazardous gases, which is the main problem with conventional FRs.
Analysis of software survivability in the early development phase is very important to validate and specify software architecture. Specifically, quantitative evaluation of survivability is very useful to determine the architecture and to estimate the risk. The risk factor can be quantified as a combination of the probability that a software system may be failed through security threat and the severity of the damages caused by the attack. In this paper, we devise a methodology for analysis of risk factor which originates from violations of security goal. We elaborate Extended Hierarchically combined Queueing Petri Nets (E-HQPN) to estimate the survival failure probability with regard to attack and combines it with the severity of the failure consequence obtained using the Functional Failure Analysis. We apply the methodology on the development of an e-business application using step-by-step approach.
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