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To determine the effects of temperature on the development and reproduction of top borer Scirpophaga excerptalis Walker (Lepidoptera: Pyralidae), the durations of different developmental stages and reproductive capacity of S. excerptalis were measured at 20, 23, 26, 29 and 32℃. The results showed that the average durations of various developmental stages of S. excerptalis shortened with increasing temperatures from 20 to 32℃. The durations to complete one life cycle were 113.17 days at 20℃, and 39.50 days at 32℃. The developmental rate of each stage and generation was positively correlated with the temperature, which was consistent with the Logistic regression model. The temperature thresholds for egg, larval, pupal and preoviposition stages and the total cycle were 13.73, 14.73, 13.91, 13.66 and 14.10℃, respectively. The effective accumulative temperature was 112.62, 370.01, 188.17, 23.82 and 718.07 degree-days (DD), respectively. The adult longevity shortened with increasing temperatures, and the highest number of eggs laid per female was 204.74 eggs at 29℃. The survival rates of eggs, larvae and the whole generation were the highest at 26℃, which were 87.25%, 56.67% and 37.21%, respectively while the highest survival rate of the pupa was 76.69% at 29℃. There was no significant difference for the total cycle at 23-29℃. The results indicated that temperature was the key factor affecting the development and reproduction of S. excerptalis, and the optimum temperature for development and reproduction ranged from 23 to 29℃.

Telenomus dignus is an important egg parasitoid of sugarcane stem borers in China. Parasitism characteristics of T. dignus were studied by the methods of its functional response and the laboratory population life table. Results showed that the parasitism capacity of T. dignus on Chilo sacchariphagus showed a functional response of Holling II model. The maximum parasitism capacity was 66.23 eggs per female at the first day. The searching efficiency was 1.0917. The processing time was 0.0151, and the correlation coefficient was 0.9041, significant. The population life table of T. dignus was established in laboratory. The average life span of females was 6.9 days, which ranged from 3 to 13 days. The number of parasitized eggs on the first day of emergence accounted for about 33% of total number of eggs laid in a lifetime, while it reached approximately 60% in the first three days. The net fecundity and the average number of parasitized eggs were 42.35 and 77.9 per female, respectively. As the dominant natural enemy, T. dignus proved to be a remarkable egg parasitoid of C. sacchariphagus, providing a basis for using T. dignus to control C. sacchariphagus in sugarcane areas.

This work examines the effect of temperature-time history on the flame synthesis of titania nanoparticles using a specially designed swirl-stabilized tubular burner with two kinds of precursor feeding modes, the tangential inlet and the central jet inlet. When the Damkohler number is less than unity, a rapidly mixed type tubular flame is well-formed, which is chosen to be the condition for flame synthesis. The ex situ characterization of the synthesized TiO2 nanoparticles shows that the particle samples from the tangential inlet feeding mode are mainly anatase (up to 84.3%) with a mean primary particle size of 13.0 ± 3.2 nm, whereas those from the central jet inlet feeding mode are large polydisperse rutile (up to 74%) nanoparticles with a mean size of 16.9 ± 8.8 nm. The significant differences in particle size and crystal phase are attributed to the varied temperature-time histories of two feeding modes, as the residence time of nanoparticles in high-temperature zone of the central jet inlet mode is much longer with larger variation than that of the tangential inlet feeding mode. Finally, the well-dispersed Pd/TiO2 nanocatalysts are generated by elaborately feeding palladium acetate through the central jet inlet and titanium tetraisopropoxide through the tangential inlets, respectively, to better match the temperature-time histories with the decomposition properties of two different precursors. The study demonstrates the potential of this swirl-stabilized burner for producing tailored single- and multi-component nanomaterials for a variety of applications.

In this work, we investigate the flame aerosol deposition of TiO 2 nanoparticles in a well-defined premixed stagnation flame based on two-dimensional phase-selective laser-induced breakdown spectroscopy (PS-LIBS). The deposited nanoparticles are in anatase phase with an average size of ∼10 nm. In PS-LIBS measurement, atomic emissions of titanium near the wavelength of 500 nm are extracted by spectral filter lenses and imaged for demonstrating the particle volume fraction distributions. The PS-LIBS signals can well depict the whole process of particle formation and transport, including the rapid gas-to-particle conversion near the flame front, dilution and concentrating of the nanoparticles induced by gas density variations, and dropping of particle volume fractions near the substrate. A quantitative model has been proposed to describe convection, thermophoresis, and diffusion of the nanoparticles. Combining the PS-LIBS measurement and the numerical simulation, it is found that, the nanoparticles concentrate outside the boundary layer at low substrate temperatures due to a joint effect of gas compression and thermophoresis. Further parametric analysis indicates that substrate temperatures and precursor loading rates can strongly affect the particle concentration boundary layer and the particle deposition rate.

Key effects of solvent formulations on the structure and morphology of optical-quality yttrium-aluminum nanocomposites using liquid-fed aerosol flame synthesis are investigated. Employing a temperature-controlled flat flame burner with inexpensive nitrates as multi-component precursors, three different solvent formulations, i.e., ethanol, ethanol/2-ethylhexanoic acid (EHA), and butanol, are studied. Adding EHA into ethanol in a 1:1 volume ratio dramatically changes the flame-made yttrium-aluminum oxides from hollow inhomogeneous powders that contain non-uniform large particles to homogeneous nanopowders around 10 nm. As characterized by in-situ phase Doppler anemometry, droplet size with increasing burner height for the EHA/ethanol case remains constant at the beginning, whereas those for both ethanol and butanol cases reduce immediately. EHA likely causes a shift from the droplet-to-particle precipitation route to the gas-to-particle route because of the formed low-boiling-point 2-ethylhexanoates from nitrates via ligand exchange. By replacing ethanol with butanol, hollow particles are produced with better crystallinity because of its high calorific value that helps to heat precursors at the droplet surface. In-situ diagnostics using phase-selective laser-induced breakdown spectroscopy, which tracks only atomic emission from the nanoparticle phase. The result shows that the Al atomic emissions in the EHA/ethanol mixture case gradually increase along the burner height, while those for both ethanol and butanol cases fluctuate, further verifying the favoring of the gas-to-particle route for producing uniform, ultrafine solid multi-oxide particles by adding EHA in solvents.

Graphene has been subjected to widespread attention, and its highly extraordinary properties have led to abundant scientific researches. The present study shows that fluffy graphene can ignite in a fairly short time upon exposure to a conventional flash light, even in an extremely low temperature environment. The ignition process is fierce and multi-points are distributed with temperatures as high as 1840K with few residues. This kind of ignition can be attributed to the graphene nanostructure efficiently converting light to heat and causing a large amount of heat to accumulate within a very short flash time with the temperature quickly exceeding the ignition point. It is further demonstrated that graphene can ignite in an environment as low as about −50 °C. When fluffy graphene was added to extremely lean methane/oxygen/nitrogen mixtures, ignition of the mixtures was successfully triggered by flash light. The ignition characteristics make graphene a promising alternative for ignition fields in harsh environment.