Effects of the grade/price and thickness of cigarette on the PM2.5 concentration of smoke.

In an attempt to promote sales of high-grade/price and slim cigarettes with lower tar and nicotine content, the State Tobacco Monopoly Administration (STMA) also known as the China National Tobacco Corporation (CNTC), whose monopoly controls all aspects of tobacco production, marketing, and distribution in China, have advertised them as safe cigarettes that cause less tobacco smoke pollution (TSP). However, cigarette smoke contains thousands of harmful components, and the effects of only tar and nicotine cannot be used to represent TSP. This study aimed to evaluate the impact of cigarette grade/price and size on TSP by measuring PM2.5 concentrations for three different grades/prices and two sizes of popular cigarettes in China. The results showed that cigarette grade/price did not significantly affect PM2.5 levels in regular (R) or slim (S) cigarettes in either sidestream or mainstream smoke. However, cigarette size had a significant effect on PM2.5 levels, with R cigarette PM2.5 being 116% higher than S cigarette PM2.5 in sidestream smoke. In mainstream smoke, this difference decreased to 31%, although R-cigarette PM2.5 levels remained higher. While S cigarette PM2.5 levels were lower than those of R cigarettes, this did not necessarily mean that S cigarettes were less harmful. The harmfulness of smoke is not only manifested in PM2.5 but also in other particulate matter such as PM10 and PM1.0. At the same time, it is also affected by smoking habits. Therefore, further experiments are required to evaluate the potential harmfulness of S cigarettes.

The mechanism of silicon on alleviating cadmium toxicity in plants: A review.

Cadmium is one of the most toxic heavy metal elements that seriously threaten food safety and agricultural production worldwide. Because of its high solubility, cadmium can easily enter plants, inhibiting plant growth and reducing crop yield. Therefore, finding a way to alleviate the inhibitory effects of cadmium on plant growth is critical. Silicon, the second most abundant element in the Earth's crust, has been widely reported to promote plant growth and alleviate cadmium toxicity. This review summarizes the recent progress made to elucidate how silicon mitigates cadmium toxicity in plants. We describe the role of silicon in reducing cadmium uptake and transport, improving plant mineral nutrient supply, regulating antioxidant systems and optimizing plant architecture. We also summarize in detail the regulation of plant water balance by silicon, and the role of this phenomenon in enhancing plant resistance to cadmium toxicity. An in-depth analysis of literature has been conducted to identify the current problems related to cadmium toxicity and to propose future research directions.

Effects of cadmium on transcription, physiology, and ultrastructure of two tobacco cultivars.

Cadmium (Cd) is one of the most toxic heavy metal pollutants worldwide. Tobacco is an important cash crop; however, the accumulation of Cd in its biomass is very high. Cadmium may enter the body of smokers with contaminated tobacco and the surrounding environment via smoke. Therefore, it is important to understand the mechanisms of Cd accumulation and tolerance in tobacco plants, especially in the leaves. In this study, the effects of Cd on the growth, accumulation, and biochemical indices of two tobacco varieties, K326 (Cd resistant) and NC55 (Cd sensitive), were studied through transcriptomic and physiological experiments. Transcriptome and physiological analyses showed differences in the expression of Cd transport and Cd resistance related genes between NC55 and K326 under Cd stress. The root meristem cells of NC55 were more severely damaged. The antioxidant enzyme activity, ABA and ZT content, chlorophyll content, photosynthetic rate, and nitrogen metabolism enzyme activity in K326 leaves were higher than in NC55. These data elucidate the mechanisms of low Cd accumulation and high Cd tolerance in K326 leaves and provide a theoretical basis for cultivating tobacco varieties with low Cd accumulation and high Cd resistance.

Temporal contrast enhancement of ultrashort pulses using a spatiotemporal plasma-lens filter.

The spatiotemporal plasma-lens filter proposed here enhances the temporal contrast of the ultrashort pulse laser by combining plasma optics and spatial filtering. Experimentally, the spatiotemporal plasma-lens filter has improved the temporal contrast by 2 orders of magnitude with 80% laser transmission efficiency under a 1 Hz repetitive laser operation. Not only were the pre-pulse and the pedestal cleaned out, but also the rising edge of the main pulse was sharpened.