Effects of Bacillus velezensis zk1 on the physiology and metabolism of peaches

Bacillus velezensis zk1 is the dominant bacterium that causing rot in peaches. However, the mechanisms through that this bacterium causes rot have not been elucidated. Here, we explored the mechanisms of peach decay caused by B. velezensis zk1. The invasion of B. velezensis zk1 in peaches resulted in an increase in glucose and arabinose contents in fruit tissues. Moreover, the relative conductivity of the fruit reached 84% after 4 days of culture with bacterial invasion. With the destruction of cells, the malondialdehyde content increased, whereas the vitamin C, dialdehyde, flavonoid and total phenol contents decreased. Polyphenol oxidase, superoxide dismutase, catalase, peroxidase, ascorbate peroxidase and ammonia lyase activities also decreased. Overall, these findings demonstrated that B. velezensis zk1 infection damaged peach chloroplasts, mitochondria, respiratory chain activity and related free radical scavenging enzyme systems, thereby disrupting the normal physiological metabolism of peaches and causing rot.     

Surface homogenizing heterostructure coatings induced by Ti3C2Tx MXene for enhanced cycle performance of lithium-rich cathode materials

The layered lithium-rich manganese-based cathode material (Li_1.2Mn_0.54Co_0.13Ni_0.13) has the significant advantage of high specific capacity, but this material also suffers serious defects, including severe capacity attenuation and voltage attenuation during the cycle. At present, most researchers have been working to optimize the cycle performance of lithium-rich materials. In this work, we propose a surface homogenizing heterostructure coating induced by MXene modification to reduce capacity reduction and voltage decay. It can be found that the initial Coulombic efficiency (ICE) increases from 77.2% for the bare electrode Li_1.2Mn_0.54Co_0.13Ni_0.13 (LMO) to 85.5% for 1.4 wt% MXene (Ti₃C₂T_x, T_x represents the surface terminations: OH, O, F) modified lithium-rich (TO2). Furthermore, the discharge specific capacity of the electrode at 5 C rate increased from 160.7 mAh g⁻¹ for LMO to 200.6 mAh g⁻¹ for TO2. More prominently, the outstanding cycle stability with capacity retention rate is 82.1% for TO2 after 200 cycles, while only 64.7% for LMO, and the average discharge voltage dropped from 0.788 to 0.468 V. In addition, the mechanism for improving the electrochemical performance is systematically studied.     

Mass and lifetime measurements of exotic nuclei in storage rings

Mass and lifetime measurements lead to the discovery and understanding of basic properties of matter. The isotopic nature of the chemical elements, nuclear binding, and the location and strength of nuclear shells are the most outstanding examples leading to the development of the first nuclear models. More recent are the discoveries of new structures of nuclides far from the valley of stability. A new generation of direct mass measurements which allows the exploration of extended areas of the nuclear mass surface with high accuracy has been opened up with the combination of the Experimental Storage Ring ESR and the FRragment Separator FRS at GSI Darmstadt. In-flight separated nuclei are stored in the ring. Their masses are directly determined from the revolution frequency. Dependent on the half-life two complementary methods are applied. Schottky Mass Spectrometry SMS relies on the measurement of the revolution frequency of electron cooled stored ions. The cooling time determines the lower half-life limit to the order of seconds. For Isochronous Mass Spectrometry IMS the ring is operated in an isochronous ion-optical mode. The revolution frequency of the individual ions coasting in the ring is measured using a time-of-flight method. Nuclides with lifetimes down to microseconds become accessible. With SMS masses of several hundreds nuclides have been measured simultaneously with an accuracy in the 2 x 10(-7)-range. This high accuracy and the ability to study large areas of the mass surface are ideal tools to discover new nuclear structure properties and to guide improvements for theoretical mass models. In addition, nuclear half-lives of stored bare and highly charged ions have been measured. This new experimental development is a significant progress since nuclear decay characteristics are mostly known for neutral atoms. For bare and highly charged ions new nuclear decay modes become possible, such as bound-state beta decay. Dramatic changes in the nuclear lifetime have been observed in highly charged ions compared to neutral atoms due to blocking of nuclear decay channels caused by the modified atomic interaction. High ionization degrees prevail in hot stellar matter and thus these experiments have great relevance for the understanding of the synthesis of elements in the universe and astrophysical scenarios in general.     

具Cauchy-Ventcel边界的阻尼波方程的对数衰减性

本文研究有界区域上具Cauchy-Ventcel边界条件的波动方程的解的衰减性质。在不要求耗散区域满足几何控制条件的情形下,我们得到了波方程的对数衰减结果。 主要结果的证明依赖于具Cauchy-Ventcel边界条件的椭圆方程的插值不等式以及关于该椭圆方程的预解式估计。为得到期望的插值不等式, 我们采用的工具是整体Carleman估计。     

Efficient localization of target in large scale farmland using generalized regression neural network

Although simple to implement, the traditional trilateration technique is generally associated with significant location estimation errors because of highly nonlinear relationship between Received Signal Strength Indicator (RSSI) and distance. In case of agricultural farmland, there is always noise uncertainty in the RSSI measurements because of signal propagation issues such as NLOS, multipath propagation, and reflection. In the context of such environmental dynamicity, the localization algorithm must be efficient in terms of Localization Accuracy and Execution Speed to provide real‐time performance. The Generalized Regression Neural Network (GRNN) is a noniterative highly parallel neural architecture with the capability to get trained quickly using very few training samples. This paper introduces a range free GRNN localization algorithm as an alternative to the traditional range‐based trilateration technique for a large scale wheat farmland. This paper also presents the modified Optimal Fitted Parametric Exponential Decay Model (OFPEDM)‐based signal path loss model to deal with the issue of environmental dynamicity. The evaluation of localization performance of the trilateration and the proposed GRNN‐based approaches is carried out with the help of Wireless Sensor Network (WSN) using three path loss models, namely, Log Normal Shadow Fading (LNSM), Original OFPEDM, and proposed Modified OFPEDM. For all these implementations, the proposed GRNN algorithm demonstrates superior localization performance (localization accuracy of the order of few centimeters) over traditional trilateration irrespective of nonlinear system dynamics, path loss model, and environmental dynamicity. The execution speed of the proposed algorithm is of the order of few milliseconds.     

弱膨胀土干湿循环直剪强度试验研究

为研究干湿循环作用下弱膨胀土的干湿循环直剪强度特征,采用南京胥河边坡弱膨胀土进行2种干密度下的干湿循环试验,对干湿循环后土体的剪应力、凝聚力及内摩擦角进行了分析,探究了膨胀土土样干湿循环后的直剪强度变化规律。试验结果表明膨胀土干湿循环后的裂缝扩展随着干湿循环次数的增加而增多、增宽,并呈现明显的不可逆性;土体的凝聚力随着干湿循环次数的增加而逐渐减小,且不同干密度土体干湿循环稳定后的凝聚力趋近于相同的稳定值;内摩擦角随干湿循环次数的增加变化规律不明显;直剪试验时的上覆压力对于土体抗剪强度测定的剪应力衰减影响明显,上覆压力越大,剪应力的衰减越小。在进行膨胀性土的边坡稳定性分析时,应采用低应力下的直剪强度参数作为分析参数,研究结论可为工程设计提供参考。     

水质模型中污染物衰减系数敏感性分析

对于河流纳污能力数值模拟问题,污染物扩散衰减系数是一个重要参数,决定了模型的准确性和可靠性。本文针对三峡大坝至葛洲坝之间河段,基于Mike21建立平面二维水质模型,以氨氮为典型污染物分析河流纳污能力,在此基础上进行了衰减系数对流量、本底浓度及有无衰减过程等因素的敏感性分析。模拟结果表明:相比本底浓度,流量的改变对污染物扩散过程的影响更为明显;污染物扩散范围随流量的增加而增加,随本底浓度的增大而降低;增大衰减系数将使污染物扩散范围减小,且高流量低本底浓度时衰减系数的取值范围较大,使得影响范围变幅最大。     

Boundary stabilisation of the wave equation in the presence of singularities

We study the boundary stabilisation of the wave equation by a nonlinear feedback active on a part of the boundary in geometric situations for which the solutions have singularities. These singularities appear at the interfaces at which the mixed Neumann–Dirichlet boundary conditions meet. Under a simple geometrical condition concerning the orientation of the boundary, we obtain sharp energy decay rates under a general growth assumption on the feedback. We show that the singularities do not affect the energy decay rates and give examples.