Influence of sample temperature on the expansion dynamics of laser-induced germanium plasma

In this paper, we investigated the influence of sample temperature on the expansion dynamics and the optical emission spectroscopy of laser-induced plasma, and Ge was selected as the test sample. The target was heated from room temperature（22 °C） to 300 °C, and excited in atmospheric environment by using a Q-Switched Nd：YAG pulse laser with the wavelength of 1064 nm. To study the plasma expansion dynamics, we observed the plasma plume at different laser energies（5.0, 7.4 and 9.4 mJ）and different sample temperatures by using time-resolved image. We found that the heated target temperature could accelerate the expansion of plasma plume. Moreover, we also measured the effect of target temperature on the optical emission spectroscopy and signal-to-noise ratio.

Effects of Expansion Temperature on Seven kinds of Hoffmann Components in Mainstream Smoke

[ Objective] To explore the effect of expansion temperature on the release of seven kinds of Hoffmann components （CO, NNK, NH3, HCN,, BaP, crotonaldehyde and phenol） from the mainstream smoke of cigarette. [ Method] The release amount of seven kinds of Hoffmann com-ponents from the mainstream smoke of cigarettes which were prepared from the cut tobacco treated under different expansion temperatures was de-termined. [ Result] Under the same expansion model, the temperature change produced certain impact on the release amount of NH~, phenol and BAP, while had no significant influence on that of CO, NNK, HCN and crotonaldehyde; under CO2 expansion model, the release amount of seven Hoffmann components was small; the reduction of expansion temperature was good for lowering the harmful index of cigarette to a certain extent. [ Conclusion] The study provides basis for optimizing the technical parameters of producinq less harmful cigarette.

Superelasticity and Tunable Thermal Expansion across a Wide Temperature Range

Materials that undergo a reversible change of crystal structure through martensitic transformation （MT） possess unusual functionalities including shape memory, superelasticity, and low/negative thermal ex- pansion. These properties have many advanced applications, such as actuators, sensors, and energy conversion, but are limited typically in a narrow temperature range of tens of Kelvin. Here we report that, by creating a nano-scale concentration modulation via phase separation, the MT can be rendered continuous by an in-situ elastic confinement mechanism. Through a model titanium alloy, we demon- strate that the elastically confined continuous MT has unprecedented properties, such as superelasticity from below 4.2 K to 500 K, fully tunable and stable thermal expansion, from positive, through zero, to negative, from below 4.2 K to 573 K, and high strength-to-modulus ratio across a wide temperature range. The elastic tuning on the MT, together with a significant extension of the crystal stability limit, provides new opportunities to explore advanced materials.