Advanced Feedback Experiment Methods With Hiher Education Theory

Advanced reserved experiment method focused cognitive law, constructivism and assimilation theory in a way that science teaching method has a profound theoretical foundation and many years of teaching practice. It is a product of deepening the reform of higher education, it is a method of quality education, innovative ability indispensable.The advanced feedback experimental method, that is, to arrange the experimental activity ahead of teaching the theory, so that students can find problems in the course of experiment and solve them in the follow-up theory teaching, it is able to fully mobilize the enthusiasm of students and let them be full of “suspense” before the class. The biggest advantage of the advanced feedback experimental method is to provide more supports to the heuristic and interactive teaching. It enables students to get the maximum amount of information of physics, chemistry, biology and other natural phenomena within limited time and space and in turn to co-operate the classroom teaching strongly. The “hide” of experimental class and the “show” of theory teaching echo each other to make the experiment and theory class linked organically. That can stir up students’ interests and passion in learning. So that they have “Suspense” before class, after-class sense of accomplishment. After more than ten years of practice, it proves that the advanced feedback experimental method is indeed a good way to reform the professional of natural science for higher education sectionand. It is worthy for recommendation

Knowing the Past to Predict the Future: Reinforcement Virtual Learning

Reinforcement Learning (RL)-based control system has received considerable attention in recent decades. However, in many real-world problems, such as Batch Process Control, the environment is uncertain, which requires expensive interaction to acquire the state and reward values. In this paper, we present a cost-efficient framework, such that the RL model can evolve for itself in a Virtual Space using the predictive models with only historical data. The proposed framework enables a step-by-step RL model to predict the future state and select optimal actions for long-sight decisions. The main focuses are summarized as: 1) how to balance the long-sight and short-sight rewards with an optimal strategy; 2) how to make the virtual model interacting with real environment to converge to a final learning policy. Under the experimental settings of Fed-Batch Process, our method consistently outperforms the existing state-of-the-art methods

Nanowrinkled Carbon Aerogels Embedded with FeN x Sites as Effective Oxygen Electrodes for Rechargeable Zinc-Air Battery.

Rational design of single-metal atom sites in carbon substrates by a flexible strategy is highly desired for the preparation of high-performance catalysts for metal-air batteries. In this study, biomass hydrogel reactors are utilized as structural templates to prepare carbon aerogels embedded with single iron atoms by controlled pyrolysis. The tortuous and interlaced hydrogel chains lead to the formation of abundant nanowrinkles in the porous carbon aerogels, and single iron atoms are dispersed and stabilized within the defective carbon skeletons. X-ray absorption spectroscopy measurements indicate that the iron centers are mostly involved in the coordination structure of FeN4, with a minor fraction (ca. 1/5) in the form of FeN3C. First-principles calculations show that the FeN x sites in the Stone-Wales configurations induced by the nanowrinkles of the hierarchically porous carbon aerogels show a much lower free energy than the normal counterparts. The resulting iron and nitrogen-codoped carbon aerogels exhibit excellent and reversible oxygen electrocatalytic activity, and can be used as bifunctional cathode catalysts in rechargeable Zn-air batteries, with a performance even better than that based on commercial Pt/C and RuO2 catalysts. Results from this study highlight the significance of structural distortions of the metal sites in carbon matrices in the design and engineering of highly active single-atom catalysts

Ruthenium atomically dispersed in carbon outperforms platinum toward hydrogen evolution in alkaline media.

Hydrogen evolution reaction is an important process in electrochemical energy technologies. Herein, ruthenium and nitrogen codoped carbon nanowires are prepared as effective hydrogen evolution catalysts. The catalytic performance is markedly better than that of commercial platinum catalyst, with an overpotential of only -12 mV to reach the current density of 10 mV cm-2 in 1 M KOH and -47 mV in 0.1 M KOH. Comparisons with control experiments suggest that the remarkable activity is mainly ascribed to individual ruthenium atoms embedded within the carbon matrix, with minimal contributions from ruthenium nanoparticles. Consistent results are obtained in first-principles calculations, where RuCxNy moieties are found to show a much lower hydrogen binding energy than ruthenium nanoparticles, and a lower kinetic barrier for water dissociation than platinum. Among these, RuC2N2 stands out as the most active catalytic center, where both ruthenium and adjacent carbon atoms are the possible active sites

Marine phytoplankton in subtropical coastal waters showing lower thermal sensitivity than microzooplankton

Temperature sensitivity of plankton in terms of activation energy (Ea, eV) in the Arrhenius equation is critical for predicting how marine productivity and carbon export will respond to ocean warming. In this study, we quantified the temperature responses of phytoplankton growth rate and microzooplankton grazing rate by conducting short-term temperature modulation experiments on natural communities at two subtropical sites with contrasting nutrient conditions. Our results showed that the activation energy of phytoplankton growth rate (Ea = 0.36 eV, 95% confidence interval [CI] = 0.28–0.44 eV) at each station was less than that of microzooplankton grazing rate (Ea = 0.53 eV, 95% CI = 0.47–0.59 eV), indicating an increasing grazing pressure on phytoplankton under warming conditions. Although the difference is consistent with that reported in previous studies, it is very likely to arise from another reason, i.e., differential proximities of the optimal temperature (Topt in nonlinear temperature responses of rates) of phytoplankton and microzooplankton to the environmental temperature, as we found that the environmental temperature is closer to the optimal temperature of phytoplankton growth than to that of microzooplankton grazing in this subtropical environment. Our results suggest that nonlinear temperature responses of plankton should be considered when evaluating and predicting the effects of ocean warming on ecosystem productivity and food web dynamics, especially in subtropical and tropical waters

Study of the correlation between vitamin D level and liver function in children with infectious mononucleosis

Objective To investigate the correlation between the serum level of 25-hydroxyvitamin D （25（OH）D） and liver function in children with infectious mononucleosis （IM）. Methods Ninety children with acute IM were enrolled into the IM group， and 40 healthy children who underwent physical examination during the same period were allocated into the control group. Serum level of 25（OH）D was determined by electrochemiluminescence and the viral load of Epstein-Barr virus DNA （EBV-DNA） in plasma was determined by quantitative fluorescent RT-PCR. Clinical data and serum 25（OH） D levels were compared between two groups. The correlation between 25（OH）D level and atypical lymphocytes， liver function parameters and plasma EBV-DNA in children with IM was analyzed. Results Serum 25（OH）D level in the IM group was significantly lower， whereas the 25（OH）D inadequacy rate was significantly higher than those in the control group （both P < 0.05）. Serum 25（OH）D level was negatively correlated with atypical lymphocytes in the IM group （P < 0.05）. The levels of alanine aminotransferase （ALT）， aspartate aminotransferase （AST）， glutamyl transpeptidase （GGT）， and adenosine deaminase （ADA） in IM children with serum 25（OH）D inadequacy were higher than those in their counterparts with adequate serum 25（OH）D （all P < 0.05）. No significant differences were found in total bilirubin （TBIL）， direct bilirubin （DBIL） and plasma EBV-DNA load between the adequate and inadequate subgroups （all P > 0.05）. In the IM group， serum 25（OH）D level was negatively correlated with ALT， GGT， and ADA （all P < 0.05）， whereas positively correlated with CHE （P < 0.05） and had no correlation with AST， TBIL or DBIL （all P > 0.05）. Conclusions Serum vitamin D insufficiency occurs in children with IM. Vitamin D may be involved in the incidence and development of the course of IM， which is probably associated with liver function impairment

Upper ocean biogeochemistry of the oligotrophic North Pacific Subtropical Gyre : from nutrient sources to carbon export

Subtropical gyres cover 26–29% of the world’s surface ocean and are conventionally regarded as ocean deserts due to their permanent stratification, depleted surface nutrients, and low biological productivity. Despite tremendous advances over the past three decades, particularly through the Hawaii Ocean Time-series and the Bermuda Atlantic Time-series Study, which have revolutionized our understanding of the biogeochemistry in oligotrophic marine ecosystems, the gyres remain understudied. We review current understanding of upper ocean biogeochemistry in the North Pacific Subtropical Gyre, considering other subtropical gyres for comparison. We focus our synthesis on spatial variability, which shows larger than expected dynamic ranges of properties such as nutrient concentrations, rates of N2 fixation, and biological production. This review provides new insights into how nutrient sources drive community structure and export in upper subtropical gyres. We examine the euphotic zone in subtropical gyres as a two-layered vertically structured system: a nutrient-depleted layer above the top of the nutricline in the well-lit upper ocean and a nutrient-replete layer below in the dimly lit waters. These layers vary in nutrient supply and stoichiometries and physical forcing, promoting differences in community structure and food webs, with direct impacts on the magnitude and composition of export production. We evaluate long-term variations in key biogeochemical parameters in both of these euphotic zone layers. Finally, we identify major knowledge gaps and research challenges in these vast and unique systems that offer opportunities for future studies

A Moving Magnetic Grid-Type Long-Range Linear Absolute Displacement Sensor

In order to overcome the shortcomings of the traditional magnetic absolute linear displacement sensors in which cables affect the flexibility and measurement range in linear motor transmission systems, this paper proposes a novel cable-free moving magnetic grid-type long-range absolute displacement sensor. The sensor consists of a magnetic grid and a signal acquisition board. The magnetic grid is a moving component that contains two rows of permanent magnet arrays, one for relative displacement measurement and the other for the displacement interval code. The signal acquisition board is a fixed component that uses n groups of two-row Hall sensor arrays for continuous absolute displacement measurement. The principle of the sensor using the 2D magnetic field signal for the relative displacement measurement is analyzed, and a measurement method based on Hall sensor arrays for coding and absolute displacement detection over n cycles is proposed. Finally, a sensor prototype is fabricated and the experiments are performed. The experimental results show that the measurement resolution of the sensor is 5 μm, and the measurement accuracy is ±14.8 μm within the measurement range of 0–98.3 mm. The proposed sensor can realize continuous absolute displacement measurement over multiple cycles without cable binding

Making comparable measurements of bacterial respiration and production in the subtropical coastal waters

Accurate estimates of bacterial carbon metabolic rates are indispensable for understanding the regulation of carbon fluxes in aquatic environments. Here, changes in bacterial growth, production, and cell volume in both pre-filtered and unfiltered seawater during 24 h incubation were monitored. The methodological artifacts during Winkler bacterial respiration (BR) measurements in subtropical Hong Kong coastal waters were assessed. Bacterial abundance increased by 3- and 1.8-fold in the pre-filtered and unfiltered seawater after incubation, respectively. Bacterial production (BP) and cell volume also showed significant enhancement. Compared with the BR measurements obtained by the Winkler method, the instantaneous free-living BR measurements, after correction, decreased by ~ 70%. The time-integrated free-living BR and BP during 24 h incubation in the pre-filtered sample provided an improved estimate of bacterial growth efficiency, which increased by ~ 52% compared to the common estimations using the noncomparable measurements of integrated free-living BR and instantaneous total BP. The overestimation of BR also exaggerated the contribution of bacteria to community respiration, affecting the understanding on the metabolic state of the marine ecosystems. Furthermore, the BR estimates by the Winkler method may be more biased in environments with a higher bacterial growth rate and tightly coupled grazing mortality, as well as in those with higher nutrient concentrations. These results reveal obvious problems associated with the BR methodology and raise a warning for caution when comparing BP and BR, as well as when making estimations of carbon flow through the complex microbial networks in aquatic ecosystems

Straight Joint Shear Performance Test of Urban Sludge Sintered Shale Bricks

In the actual engineering design, it is too conservative for the calculation results for the urban sludge sintered shale brick to use the shear strength formula in the Design Specifications of Masonry Structure. To more effectively calculate this formula, this paper researches the straight joint shear performance test of urban sludge sintered solid shale bricks and porous brick masonry, and analyzes the failure mode of two kinds of brick masonry, and reaches the proposed formula of the straight joint shear strength. Then, this paper compares the proposed formula with the corresponding formulas in the specification, and reaches a high safety stock of the formula in the specification, and needs to correct the coefficient of material properties in the formula in the specification