Yoghurt is fermented milk which results from the exclusive action of <i><span style="font-family:Verdana;">Lactobacillus</span></i> <i><span style="font-family:Verdana;&...Yoghurt is fermented milk which results from the exclusive action of <i><span style="font-family:Verdana;">Lactobacillus</span></i> <i><span style="font-family:Verdana;">delbrueckii</span></i><span style="font-family:Verdana;"> subsp </span><i><span style="font-family:Verdana;">bulgaricus</span></i><span style="font-family:Verdana;"> and </span><i><span style="font-family:Verdana;">Streptococcus</span></i> <i><span style="font-family:Verdana;">thermophilus</span></i><span style="font-family:Verdana;">. However, a disruption of the bacterial growth can lead to significant industrial losses. Currents monitoring methods, based on the checking of the pH during the fermentation step are not always satisfactory. The NeOse Pro system, a portable electronic nose, is a mean to obtain immediately aromatic profiles. In this work, we applied this technology to the yoghurt ecosystem, a highly hydrated product. The profiles obtained allowed us to discriminate yoghurts before and after fermentation. In detail, the discrepancy between the two bacteria cultured alone was slight. It was also the case when we compared different initial bacterial ratios. However, two different mixes of bacteria led to clearly distinguishable profiles. A GC/MS analysis performed on products fermented 7</span><span><span><span style="font-family:;" "=""> </span></span></span><span><span><span>h allowed us to explain the detection of acetaldehyde by the stimulation of some captors of the apparatus. NeOse Pro is so convenient to study the fermentation of yogurt.</span></span></span>展开更多
Neonicotinoid insecticides(NEOs)have become an integral part of the global insecticide market due to their high efficiency and low toxicity.However,their environmental persistence has raised significant ecological con...Neonicotinoid insecticides(NEOs)have become an integral part of the global insecticide market due to their high efficiency and low toxicity.However,their environmental persistence has raised significant ecological concerns.Dongting Lake represents a vital freshwater lake in China,and its ecosystem health directly affects regional ecological balance and people’s livelihoods.This study systematically investigated the occurrence characteristics and ecological risks of NEOs in water bodies and sediments across the Dongting Lake basin.Based on surface water and sediment samples collected from 26 representative sampling sites,this study quantified nine NEOs using liquid chromatography triple quadrupole mass spectrometry.Furthermore,it assessed ecological risks posed by the NEOs using the risk quotient(RQ)method and fugacity modeling.The results revealed the presence of six NEOs in the water bodies:imidacloprid(IMI),acetamiprid(ACE),clothianidin(CLO),thiamethoxam(THIA),flonicamid(FLO),and dinotefuran(DIN).The total concentrations of these six NEOs averaged 275.11 ng/L.Five predominant NEOs(i.e.,IMI,THIA,ACE,CLO,and DIN)were identified in the sediments,with a mean concentration of 0.31 ng/g.The NEO concentrations in the water bodies across the Dongting Lake basin increased in the order of the Xiangjiang,Zishui,Yuanjiang,and Lishui rivers(collectively referred to as the Four Rivers),the mainstream of Dongting Lake,the Xinqiang River,the Miluo River,and the Hudu,Ouchi,and Songzi rivers(collectively referred to as the Three Outlets).Sediments from tributaries progressively accumulate in the lake.The ecological risk assessment identified IMI and DIN as the highest-risk compounds(RQ>1),with high-risk areas concentrated in the mainstream of Dongting Lake and the Ouchi,Miluo,and Hudu rivers.The fugacity model showed that IMI,ACE,and THIA are prone to diffuse from sediments to water bodies in most areas,with fugacity fractions(ff)values of greater than 0.5.In contrast,the mainstream of Dongting Lake acts as a sink of CLO and DIN(ff values:<0.5).Sediments at the lake’s outlet emerge as an important sink of NEOs.Based on the results of this study,it is advisable to strengthen the supervision of NEO applications in agricultural areas and to implement zonal control strategies.These measures will help reduce ecological risks and protect the safety of water ecosystems in the Dongting Lake region.展开更多
We have observed three near-Earth objects(NEOs), 2017 VR12, Camillo and Midas, during 2018.The observations were made with the 1-m telescope, operated by Yunnan Observatories, over two nights.Their precise astrometric...We have observed three near-Earth objects(NEOs), 2017 VR12, Camillo and Midas, during 2018.The observations were made with the 1-m telescope, operated by Yunnan Observatories, over two nights.Their precise astrometric positions are derived from 989 CCD observations. The theoretical positions of asteroids are retrieved from the Jet Propulsion Laboratory(JPL) Horizons System and Institut de M′ecanique C′eleste et de Calcul des ′Eph′em′erides(IMCCE). The positions of three asteroids are measured with respect to stars in the Gaia DR2 star catalog. For 2017 VR12, the means(O-C) of right ascension and declination are -0.090′′and-0.623′′respectively based on the published JPL ephemeris, but the corresponding means(O-C) are 3.122′′and-0.636′′based on the published IMCCE ephemeris. The great difference in declination could be explained by several factors.(1) The degraded CCD images caused by the fast apparent motion of the objects lead to a reduction in positioning accuracy.(2) The poor timing system may introduce systematic errors, especially in the high speed direction.(3) The asteroid may be perturbed by Earth when it approaches the Earth too closely. These astrometric results demonstrate that the centroid centering method can reduce the dispersion of non-Gaussian images as compared with the PSF modeling method.For Camillo and Midas, the astrometric results are consistent based on the two ephemerides. Implementing a high-precision timing system, and analyzing some astronomical effects and geometric distortions in CCD images should be carefully considered in future works.展开更多
文摘Yoghurt is fermented milk which results from the exclusive action of <i><span style="font-family:Verdana;">Lactobacillus</span></i> <i><span style="font-family:Verdana;">delbrueckii</span></i><span style="font-family:Verdana;"> subsp </span><i><span style="font-family:Verdana;">bulgaricus</span></i><span style="font-family:Verdana;"> and </span><i><span style="font-family:Verdana;">Streptococcus</span></i> <i><span style="font-family:Verdana;">thermophilus</span></i><span style="font-family:Verdana;">. However, a disruption of the bacterial growth can lead to significant industrial losses. Currents monitoring methods, based on the checking of the pH during the fermentation step are not always satisfactory. The NeOse Pro system, a portable electronic nose, is a mean to obtain immediately aromatic profiles. In this work, we applied this technology to the yoghurt ecosystem, a highly hydrated product. The profiles obtained allowed us to discriminate yoghurts before and after fermentation. In detail, the discrepancy between the two bacteria cultured alone was slight. It was also the case when we compared different initial bacterial ratios. However, two different mixes of bacteria led to clearly distinguishable profiles. A GC/MS analysis performed on products fermented 7</span><span><span><span style="font-family:;" "=""> </span></span></span><span><span><span>h allowed us to explain the detection of acetaldehyde by the stimulation of some captors of the apparatus. NeOse Pro is so convenient to study the fermentation of yogurt.</span></span></span>
基金jointly supported by project of the China Geological Survey(DD20243375,DD20230478)the Key Research and Development Program of Hunan Province(2023SK2066)the Natural Science Foundation of Hunan Province(2024JJ7620).
文摘Neonicotinoid insecticides(NEOs)have become an integral part of the global insecticide market due to their high efficiency and low toxicity.However,their environmental persistence has raised significant ecological concerns.Dongting Lake represents a vital freshwater lake in China,and its ecosystem health directly affects regional ecological balance and people’s livelihoods.This study systematically investigated the occurrence characteristics and ecological risks of NEOs in water bodies and sediments across the Dongting Lake basin.Based on surface water and sediment samples collected from 26 representative sampling sites,this study quantified nine NEOs using liquid chromatography triple quadrupole mass spectrometry.Furthermore,it assessed ecological risks posed by the NEOs using the risk quotient(RQ)method and fugacity modeling.The results revealed the presence of six NEOs in the water bodies:imidacloprid(IMI),acetamiprid(ACE),clothianidin(CLO),thiamethoxam(THIA),flonicamid(FLO),and dinotefuran(DIN).The total concentrations of these six NEOs averaged 275.11 ng/L.Five predominant NEOs(i.e.,IMI,THIA,ACE,CLO,and DIN)were identified in the sediments,with a mean concentration of 0.31 ng/g.The NEO concentrations in the water bodies across the Dongting Lake basin increased in the order of the Xiangjiang,Zishui,Yuanjiang,and Lishui rivers(collectively referred to as the Four Rivers),the mainstream of Dongting Lake,the Xinqiang River,the Miluo River,and the Hudu,Ouchi,and Songzi rivers(collectively referred to as the Three Outlets).Sediments from tributaries progressively accumulate in the lake.The ecological risk assessment identified IMI and DIN as the highest-risk compounds(RQ>1),with high-risk areas concentrated in the mainstream of Dongting Lake and the Ouchi,Miluo,and Hudu rivers.The fugacity model showed that IMI,ACE,and THIA are prone to diffuse from sediments to water bodies in most areas,with fugacity fractions(ff)values of greater than 0.5.In contrast,the mainstream of Dongting Lake acts as a sink of CLO and DIN(ff values:<0.5).Sediments at the lake’s outlet emerge as an important sink of NEOs.Based on the results of this study,it is advisable to strengthen the supervision of NEO applications in agricultural areas and to implement zonal control strategies.These measures will help reduce ecological risks and protect the safety of water ecosystems in the Dongting Lake region.
基金financially supported by the National Natural Science Foundation of China (Grant Nos. 11503083 and 11403101)
文摘We have observed three near-Earth objects(NEOs), 2017 VR12, Camillo and Midas, during 2018.The observations were made with the 1-m telescope, operated by Yunnan Observatories, over two nights.Their precise astrometric positions are derived from 989 CCD observations. The theoretical positions of asteroids are retrieved from the Jet Propulsion Laboratory(JPL) Horizons System and Institut de M′ecanique C′eleste et de Calcul des ′Eph′em′erides(IMCCE). The positions of three asteroids are measured with respect to stars in the Gaia DR2 star catalog. For 2017 VR12, the means(O-C) of right ascension and declination are -0.090′′and-0.623′′respectively based on the published JPL ephemeris, but the corresponding means(O-C) are 3.122′′and-0.636′′based on the published IMCCE ephemeris. The great difference in declination could be explained by several factors.(1) The degraded CCD images caused by the fast apparent motion of the objects lead to a reduction in positioning accuracy.(2) The poor timing system may introduce systematic errors, especially in the high speed direction.(3) The asteroid may be perturbed by Earth when it approaches the Earth too closely. These astrometric results demonstrate that the centroid centering method can reduce the dispersion of non-Gaussian images as compared with the PSF modeling method.For Camillo and Midas, the astrometric results are consistent based on the two ephemerides. Implementing a high-precision timing system, and analyzing some astronomical effects and geometric distortions in CCD images should be carefully considered in future works.
