A novel strategy for quantitative analysis of soil pH via laser-induced breakdown spectroscopy coupled with random forest

pH is one of the significant properties of soil,and is closely related to the decomposition of soil organic matter,anion-cation balance,growth of plants and many other soil processes.In the present work,laser-induced breakdown spectroscopy(LIBS) technique coupled with random forest(RF) was proposed to quantify the pH of soil.First,LIBS spectra of soil was collected,and some common elements in soil were identified based on the National Institute of Science and Technology database.Then,in order to obtain a better predictive result,the influence of different input variables(full spectrum,different spectral ranges,the intensity of characteristic bands and characteristic lines) on the predictive performance of RF calibration model was explored with the evaluation indicators of root mean square error(RMSE) and coefficient of determination(R2),the characteristic bands of four elements(AI,Ca,Mg and Si) were determined as the optimal input variables.Finally,the predictive performance of RF calibration model was compared with partial least squares calibration model with the optimal input variables and model parameters,and RF calibration model showed a better predictive performance,and the four evaluation indicators of R_p^2,RMSEP,mean absolute error and mean relative error were 0.9687,0.1285,0.1114 and 0.0136,respectively.It indicates that LIBS technique coupled with RF algorithm is an effective method for pH determination of soil.

Yiqi Huoxue prescription can prevent and treat post-MI myocardial remodeling through promoting the expression of AMPK signal pathway

Objective:To investigate how Yiqi Huoxue (YQHX) prescription regulates mitochondrial biosynthesis and ATP synthesis via AMP-activated protein kinase (AMPK) and to reveal its molecular mechanism in preventing and treating post-MI myocardial remodeling.Methods:The MI animal model of myocardial infarction were established by ligating Sprague Dawley (SD) rats' left anterior descending coronary arteries;the animals were randomly divided into MI group,YQHX prescription group and perindopril group,and a sham operation group was set at the same time.Related drug intervention was administered on the 2nd day after surgery,the YQHX group was given Astragalus,angelica,ginseng,Ligusticum wallichii and pseudoginseng,provided by the Dongzhimen Hospital of Beijing University of Chinese Medicine,once per day,at a dose of 21 g/kg body weight/day (the clinical equivalent dose based on a previous study),and the changes in relevant indicators were observed at 1 week and 4 weeks.Echocardiography (ECG) was used to observe the changes in rat cardiac structure and functions;the morphology-based technique was used to observe the changes in myocardial cells and mitochondria;the expression of AMPK signal pathway-related proteins and mRNA was detected using western blotting and real-time fluorescence quantification respectively,while fluorescence enzyme-labeled method was used for detecting ATP synthesis.Results:Cardiac structure and functions:Compared with the MI group at 1 week,the YQHX prescription group and the perindopril group exhibited increased LVEF and LVFS (Pall <.05);their LVEDs and LVEDd were reduced but suggested no statistically significant differences (F =2.258,F =0.3464,Pall >.05).At 4 weeks,both LVEF and LVFS were elevated in the YQHX prescription group (P =.008,.009) and the perindopril group (P =.279,.333),where differences in the later group indicated no statistical significance;the YQHX prescription group and the perindopril group were also featured by reduced LVEDs and LVEDd (Pall <.05).Morphology:Compared with the MI group at two time nodes,the YQHX prescription group and the perindopril group exhibited significant improvement in the pathological changes in myocardial cells and mitochondrial structure.Expression of AMPK signal pathway-related proteins and mRNA:The expression of both pLKB1 and pAMPK proteins followed a rising trend in the YQHX prescription group and the perindopril group at 1 week.The expression of LKB1mRNA and AMPKmRNA was elevated (Pall <.05).The increased expression of PGC-1α,NRF1 and mtTFA proteins demonstrated statistically significant differences (Pall <.05).The expression of mtDNA protein followed an increasing trend.At 4 weeks,the expression of both pLKB1 and pAMPK proteins was elevated (Pall <.05).Heightened expression was also reported in LKB1mRNA and AMPKmR-NA (Pall <.05).The increased expression of PGC-1α,NRF1,mtTFA and mtDNA proteins demonstrated statistically significant differences (Pall <.05).ATP synthesis:ATP synthesis was increased in the YQHX prescription group and the perindopril group at both 1 week and 4 weeks (Pall <.001).Conclusion:The possible mechanism of YQHX prescription for preventing and treating post-MI myocardial remodeling may function through strengthening the activation AMPK signal pathway by LKB1,thus further increasing the expression of downstream transcription factor proteins and initiating mitochondrial replication and transcription;as a result,the YQHX prescription can improve the post-MI damage in mitochondrial morphological structure in the tissue at heart marginal zone as well as enhance mitochondrial biosynthesis and ATP synthesis.

von Neumann measurement-related matrices and the nullity condition for quantum correlation

We study von Neumann measurement-related matrices, and the nullity condition of quantum correlation. We investigate the properties of these matrices that are related to a von Neumann measurement. It is shown that these(m^2-1)×(m^2-1) matrices are idempotent, and have rank m-1. These properties give rise to necessary conditions for the nullity of quantum correlations in bipartite systems. Finally, as an example we discuss quantum correlation in Bell diagonal states.

Coherence evolution in two-qubit system going through amplitude damping channel

In this paper, we analyze the evolution of quantum coherence in a two-qubit system going through the amplitude damping channel. After they have gone through this channel many times, we analyze the systems with respect to the coherence of their output states. When only one subsystem goes through the channel, frozen coherence occurs if and only if this subsystem is incoherent and an auxiliary condition is satisfied for the other subsystem. When two subsystems go through this quantum channel, quantum coherence can be frozen if and only if the two subsystems are both incoherent. We also investigate the evolution of coherence for maximally incoherent-coherent states and derive an equation for the output states after one or two subsystems have gone through the amplitude damping channel.