Abstract'Chaling' common wild rice (CWR, Oryza rufipogon Griff.), found in Chaling county, Hunan province, China, is one of the only two wild rice populations grown northernmost in the world. Although the cold tolerance of 'Chaling' CWR is extremely strong, its photosynthetic characteristics under cold stress remain unknown. In this study, the photosynthetic parameters of leaves at tiller stage in 'Chaling' CWR were first determined under the conditions of cold stress (15 °C) and normal temperature (28 °C), and then compared with those in the standard rice cultivars including indica 'Guangluai 4', indica 'Y-Liangyou 1' (a Chinese hybrid rice with super high grain yield), and japonica 'Nipponbare' under the same temperature conditions. The results showed that the net photosynthetic rate, the total chlorophyll and total carotenoid contents, the maximum quantum yield of PSII, the apparent quantum yield, and the carboxylation efficiency in 'Chaling' CWR were all significantly higher than those in the standard rice cultivars under cold stress (P < 0.05). The ratios of these parameters in 'Chaling' CWR under cold stress to those under normal temperature condition were 47.9 ~ 84.9%, much higher than those in the standard rice cultivars, which were 3.1 ~ 73.8%. These results indicate that the photosynthetic characteristics of 'Chaling' CWR under cold stress are excellent. Our findings would have an enormous benefit if the trait of the cold stress tolerance of 'Chaling' CWR is transferred to the cultivated rice via the traditional breeding or molecular breeding.Keywords: apparent quantum yield, carboxylation efficiency, chlorophyll fluorescence, photosynthetic pigment, photosynthetic rate Abbreviations: A-C i curve -assimilation rate plotted against intercellular CO 2 concentration, AQY -apparent quantum yield, Car -carotenoids, CE -carboxylation efficiency, Chl -chlorophyll, CWR -common wild rice, F o -the minimal chlorophyll fluorescence value, F m -the maximum chlorophyll fluorescence value, F v /F m -variable to maximum fluorescence, P n -net photosynthetic rate.

Background: Rice is the staple food of many people around the world. However, most rice varieties, especially widely grown indica varieties and hybrids, are sensitive to cold stress. In order to provide a basis for the utilization of a common wild rice (CWR, Oryza rufipogon Griff.) named 'Chaling' CWR in cold-tolerant rice breeding and deepen the understanding of rice cold tolerance, the cold tolerance of ratoon 'Chaling' CWR was studied under the stress of the natural low temperature in winter in Changsha, Hunan province, China, especially under the stress of abnormal natural low temperature in Changsha in 2008, taking other ratoon CWR accessions and ratoon cultivated rice phenotypes as control. Results:The results showed that ratoon 'Chaling' CWR can safely overwinter under the natural conditions in Changsha (28° 22′ N), Hunan province, China, which is a further and colder northern place than its habitat, even if it suffers a long-term low temperature stress with ice and snow. In 2008, an extremely cold winter appeared in Changsha, i.e., the average daily mean temperature of 22 consecutive days from January 13 to February 3 was − 1.0 °C, and the extreme low temperature was − 4.7 °C. After subjected to this long-term cold stress, the overwinter survival rate of ratoon 'Chaling' CWR was 100%, equals to that of ratoon 'Dongxiang' CWR which is northernmost distribution in the word among wild rice populations, higher than those of ratoon 'Fusui' CWR, ratoon ' Jiangyong' CWR, and ratoon 'Liujiang' CWR (63.55-83.5%) as well as those of ratoon 'Hainan' CWR, ratoon 'Hepu' CWR, and all the ratoon cultivated rice phenotypes including 3 japonica ones, 3 javanica ones, and 5 indica ones (0.0%). Conclusions:The results indicate that ratoon 'Chaling' CWR possesses strong cold tolerance and certain freezing tolerance.

On-machine measurement is a high-efficient measure method in NC machining, and there are pre-travel errors during measurement. What is more, these errors tend to present anisotropy, and affect the measurement accuracy. This paper aimed at measuring the anisotropy of probe’s pre-travel error. First, the standard ball is measured by changing the probe angle with the same machine tool moving direction, and the pre-travel errors with different probe angles under the same machine tool errors are obtained. Then, the machine tool backlash errors are measured and compensated, and the pre-travel errors with different probe angle are obtained. Finally, the mathematical model of pre-travel error is established. The method proposed in this paper can be used to determine probe’s pre-travel error with anisotropy.

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Probiotics have a cholesterol-lowering effect. Multi-strain probiotics outperformed single-strain probiotics due to the interaction of strains. Hence, we expect to develop a high-efficiency multi-strain probiotic (MSP) for lowering cholesterol. Three strains, including Lactobacillus casei S1, Enterococcus faecium S4, and Lactobacillus harbinensis S6, were used to develop the MSPs. To evaluate their effect, gastrointestinal tolerance, bile salt hydrolase (BSH) activity, cholesterol-lowering rate, antioxidant ability, gamma-aminobutyric acid (GABA) production, and antibiotic sensitivity were determined. The triple lactic acid bacteria probiotic (TLP) was the most efficient one. After 24 h treatment with artificial gastric fluid, 47.88% of TLP survived. TLP exhibited the highest BSH activity (149.40 U·mL−1) and cholesterol-lowering rate (75.05%) in vitro, with co-precipitation reducing the majority of cholesterol. The reducing power and superoxide radical scavenging rate of the cell-free supernatant and the hydroxyl radical scavenging rate in viable cells were 1.52, 85.03%, and 89.66%, respectively, and the GABA production was 0.67 mg·mL−1, which enhanced the health benefit effects. By fuzzy mathematical analysis, TLP was the optimal probiotic and was competitive with commercial probiotics. The three strains were susceptible to 13 antibiotics. Therefore, TLP has the potential to develop into a cholesterol-lowering probiotic preparation.