Biochemical properties of oxidases of Yali pear

The biochemical properties of polyphenol oxidase (PPO), peroxidase (POD) and ascorbate peroxidase (APX) from Yali pear were investigated. The optimum pH and temperature of three enzymes was 5.6, 4.0, 7.0 and 20, 40, 50°C, respectively. Enzyme kinetics results showed that the Michaelis constant (Km) and maximum velocity (Vmax) of PPO for catechol were 0.22 M and 1111 U/ml/min. The Km and Vmax values of POD for guaiacol were 0.14 M and 1429 U/ml/min. The Km of APX for ascorbic acid and H2O2 were 0.41 and 0.083 mM, respectively, and the Vmax of APX was 455 and 208 U/ml/min for ascorbic acid and H2O2, respectively. The inhibitory effects of the four inhibitors (ascorbic acid, citric acid, L-cysteine and phytic acid) on each enzyme were different, suggesting that the composite inhibitor is more appropriate for processing of Yali pear.Keywords: Yali pear, polyphenol oxidase, peroxidase, ascorbate peroxidase, biochemical propert

The comprehensive effect of natural food quality and quantity on growth rate of herbivore consumers

The performance of herbivore consumers in freshwater ecosystems is influenced by food quality and quantity, which are crucial factors in understanding energy flow. However, the comprehensive effects of these factors on consumer growth based on natural food research remain unclear. To address this gap, we conducted a growth experiment culturing the Cladocera Daphnia similis in natural lake water collected from 30 subtropical lakes. Our results showed that the seston concentration (SC), seston phosphorus (seston P), and seston carbon: phosphorus ratio (seston C:P, in moles) were the most important factors in influencing the growth rate of D. similis according to the Random Forest model. Specifically, the growth rate of D. similis was significantly positive correlated with SC and seston P, and significantly negative correlated with seston C:P. D. similis exhibited the optimal growth performance within the seston C:P range of 32.8 to 69.8, with a sharp decline in growth rate observed at a break point of seston C:P of 70. The combined effect of food quality and quantity on growth rate was that higher SC (≥0.26 mg C/L), lower seston C:P (≤69.80), and higher P (≥0.11 mmol/g) were associated with significantly higher growth rates. Additionally, the growth rate increased significantly with the biomass of cryptophyte, indicating the importance of food composition. Our study shows that the growth rate of D. similis is co-affected by the quality and quantity of natural food. SC, seston C:P, seston P and algae composition are reliable indicators for assessing the growth rate of consumer in freshwater ecosystems. The inhibitory effect of low C:P on consumer growth should be applied with caution when assessing the development of herbivore consumers in natural lakes

Reconstructing human activities via coupling mobile phone data with location-based social networks

In the era of big data, the ubiquity of location-aware portable devices provides an unprecedented opportunity to understand inhabitants' behavior and their interactions with the built environments. Among the widely used data resources, mobile phone data is the one passively collected and has the largest coverage in the population. However, mobile operators cannot pinpoint one user within meters, leading to the difficulties in activity inference. To that end, we propose a data analysis framework to identify user's activity via coupling the mobile phone data with location-based social networks (LBSN) data. The two datasets are integrated into a Bayesian inference module, considering people's circadian rhythms in both time and space. Specifically, the framework considers the pattern of arrival time to each type of facility and the spatial distribution of facilities. The former can be observed from the LBSN Data and the latter is provided by the points of interest (POIs) dataset. Taking Shanghai as an example, we reconstruct the activity chains of 1,000,000 active mobile phone users and analyze the temporal and spatial characteristics of each activity type. We assess the results with some official surveys and a real-world check-in dataset collected in Shanghai, indicating that the proposed method can capture and analyze human activities effectively. Next, we cluster users' inferred activity chains with a topic model to understand the behavior of different groups of users. This data analysis framework provides an example of reconstructing and understanding the activity of the population at an urban scale with big data fusion

Effect of ligustrazine injection on the change of oxidative stress system during renal ischemia reperfusion injury in rabbits

目的  通过由兔肾脏缺血/再灌注损伤（IRI）导致的氧化应激体系中的变化，研究中药川芎嗪对IRI干预下的作用机制。方法  建立持续性阻断兔双侧肾动脉血流1h，再灌注5h的肾IRI动物模型。日本大耳兔32只，随机分成3组（n=10）：假手术组(sham，S组)，缺血/再灌注组(ischemia-reperfusion，IR组)，川芎嗪干预缺血/再灌注组（ligustrazine+ ischemia-reperfusion，LZ组），另外两只作为补充实验中意外死亡之用。于缺血前、缺血1h、再灌注1h、3h和5h依次经颈总动脉抽血用以检测超氧化物歧化酶（SOD）活力、黄嘌呤氧化酶（XO）活力以及丙二醛（MDA）含量。在实验结束后取兔肾组织依次检测SOD、XO活力以及MDA含量，并对其进行电镜观察。结果  随着肾缺血和再灌注时间的增加，IR组和LZ组血浆中的XO活力和MDA含量逐渐呈上升趋势，但同时间点LZ组较于IR组明显降低（均P<0.01）；SOD活力随着肾缺血和再灌注时间的增加而逐渐呈下降趋势，但同时间点下，LZ组较于IR组均明显偏高（均P<0.01）。IR组和LZ组相较于S组，肾组织XO活力、MDA含量均明显升高，SOD活力均明显降低（均P<0.01）；而LZ组肾组织中的XO活力、MDA含量均显著低于IR组，SOD活力均显著高于IR组，差异有非常显著性（均P<0.01），LZ组肾组织细胞的超微结构异常改变较IR组显著减轻。结论  川芎嗪能够使氧自由基水平降低，氧化应激损伤减轻，具有保护肾缺血/再灌注损伤的作用。Objective: To investigate the change of oxidative stress system during renal ischemia-reperfusion injury, and to study the mechanism of Ligustrazine on IRI under the intervention. Methods: Establish the IRI animal model by persistent blocking rabbits’ bilateral renal artery blood flow for 1 hour, then reperfusion for another 5 hours. Japanese big ear rabbits, 32, were randomly divided into three groups (n=10): sham operation group (group S), ischemia/reperfusion group (group IR), the effect of ligustrazine on ischemia/ reperfusion group (LZ group), the other two being added in the experiment for accidental death. In 1 hour before ischemia, ischemia, reperfusion 1h, 3h and 5h in turn to check the enzyme activity of superoxide dismutase (SOD), xanthine oxidase (XO) and the content of malondialdehyde (MDA) by getting the blood from common carotid artery. At the end of the experiment, the rabbit’s kidney was used to check the enzyme activity of XO, SOD and the content of MDA, then to observe the morphological changes under the electron microscopy. Results: With the increase of renal ischemia and reperfusion time, XO activity and MDA content of IR group and LZ group in plasma gradually up, they were significantly lower in LZ group than in IR group at same time point (all P<0.01), the activity of SOD in plasma was shown a time-dependent decline in both IR group and LZ group, whereas it was significant higher in LZ group compared with IR group at same time point during ischemia reperfusion (all P<0.01). SOD activity gradually decreased with the increase of renal ischemia and reperfusion time, but at the same time point, LZ group compared with IR group were significantly higher (P<0.01), however, for LZ group, as compared with IR group, activity of XO, content of MDA were increased remarkably while activity of SOD was decreased significantly in kidney tissue (all P<0.01) the abnormal changes of ultrastructure were mitigated significantly. Conclusion: Ligustrazine may attenuate renal ischemia-reperfusion injury by dropping oxygen free radical generation and enhancing oxygen free radical scavenge so that it can antagonize oxidative stress

Reduced European aerosol emissions suppress winter extremes over northern Eurasia

Winter extreme weather events receive major public attention due to their serious impacts, but the dominant factors regulating their interdecadal trends have not been clearly established. Here, we show that the radiative forcing due to geospatially redistributed anthropogenic aerosols mainly determined the spatial variations of winter extreme weather in the Northern Hemisphere during 1970–2005, a unique transition period for global aerosol forcing. Over this period, the local Rossby wave activity and extreme events (top 10% in wave amplitude) exhibited marked declining trends at high latitudes, mainly in northern Eurasia. The combination of long-term observational data and a state-of-the-art climate model revealed the unambiguous signature of anthropogenic aerosols on the wintertime jet stream, planetary wave activity and surface temperature variability on interdecadal timescales. In particular, warming due to aerosol reductions in Europe enhanced the meridional temperature gradient on the jet’s poleward flank and strengthened the zonal wind, resulting in significant suppression in extreme events over northern Eurasia. These results exemplify how aerosol forcing can impact large-scale extratropical atmospheric dynamics, and illustrate the importance of anthropogenic aerosols and their spatiotemporal variability in assessing the drivers of extreme weather in historical and future climate

Holographic Storage of Biphoton Entanglement

Coherent and reversible storage of multi-photon entanglement with a multimode quantum memory is essential for scalable all-optical quantum information processing. Although single photon has been successfully stored in different quantum systems, storage of multi-photon entanglement remains challenging because of the critical requirement for coherent control of photonic entanglement source, multimode quantum memory, and quantum interface between them. Here we demonstrate a coherent and reversible storage of biphoton Bell-type entanglement with a holographic multimode atomic-ensemble-based quantum memory. The retrieved biphoton entanglement violates Bell's inequality for 1 microsecond storage time and a memory-process fidelity of 98% is demonstrated by quantum state tomography.Comment: 5 pages, 4 figures, accepted by Phys. Rev. Let

Reduced European aerosol emissions suppress winter extremes over northern Eurasia

Winter extreme weather events receive major public attention due to their serious impacts, but the dominant factors regulating their interdecadal trends have not been clearly established. Here, we show that the radiative forcing due to geospatially redistributed anthropogenic aerosols mainly determined the spatial variations of winter extreme weather in the Northern Hemisphere during 1970–2005, a unique transition period for global aerosol forcing. Over this period, the local Rossby wave activity and extreme events (top 10% in wave amplitude) exhibited marked declining trends at high latitudes, mainly in northern Eurasia. The combination of long-term observational data and a state-of-the-art climate model revealed the unambiguous signature of anthropogenic aerosols on the wintertime jet stream, planetary wave activity and surface temperature variability on interdecadal timescales. In particular, warming due to aerosol reductions in Europe enhanced the meridional temperature gradient on the jet’s poleward flank and strengthened the zonal wind, resulting in significant suppression in extreme events over northern Eurasia. These results exemplify how aerosol forcing can impact large-scale extratropical atmospheric dynamics, and illustrate the importance of anthropogenic aerosols and their spatiotemporal variability in assessing the drivers of extreme weather in historical and future climate