Purpose
Understanding the soil nitrogen (N) mineralization potential (
N
0
) and crop N availability during the growing season is essential for improving nitrogen use efficiency (NUE) and preventing ...over-fertilization, which lead to negative environmental impacts.
Methods
Five black soils with different levels of fertility were selected in Northeast China. The
N
0
and kinetics of these soils were estimated through laboratory experiments at different incubation temperatures (15, 25, and 35 °C). N mineralization dynamics were simulated using field soil temperature according to the incubation results. Moreover, the N uptake dynamics of maize were simulated according to the literature.
Results
Compared with the very low-fertility soils, the cumulative mineralized nitrogen increased under all incubation temperatures (15, 25, and 35 °C), by 48–136%, 8–61%, and 24–59%, respectively, in the medium- and high-fertility soils. The highest
N
0
values (96.90, 115.31, and 121.33 mg/kg at the three different temperatures) were recorded in the very high-fertility soils. The soil N mineralization dynamics and N uptake of maize in the growing season were highly consistent over time, although the soil N supply could not meet the maize growth requirements. The higher the soil fertility, the lower the N fertilizer requirement.
Conclusions
Different fertilizer strategies were developed based on the cumulative mineralized N, N uptake by maize, and NUE in soils with different fertility levels. We suggested a reduction of 50–65 kg N/ha in N fertilizer in the two highest fertility soils. This study provided basic data to reduce chemical N fertilizer to improve NUE and reduce negative environmental impacts.
This study is interested in how to utilise the virtual time reversal (VTR) technique to locate the continuous AE source in cylindrical shell structure. Thus, a six-AE-sensor monitoring network was ...designed to divide cylindrical surface into two symmetric semi-cylindrical monitoring areas whose four vertexes and two geometrical centres were defined as the measuring points. The AE source can be located in certain semi-cylindrical monitoring area whose centre measuring point first captured the emitted AE signal. Besides, the response signals at other four measuring points were used to localise the AE source. To realise the VTR focusing of the AE signals, the proposed method solved two key problems. One is to search the shortest helical path between two arbitrary points on a cylindrical surface, which can provide the shortest distance from AE source to sensor. The other is to extract the specific frequency coefficients of wavelet transform for the continuous AE signal, which can meet with the requirement for the instantaneous abrupt characteristic of the signals to be processed using VTR focusing technique. Finally, a continuous leak experiment was carried out on a gas-filled steel pipe. The corresponding localisation method can accurately estimate the location of the continuous leak source.
Graphene on SiO2 enables fabrication of Si-technology-compatible devices, but a transfer of these devices from other substrates and direct growth have severe limitations due to a relatively small ...grain size or device-contamination. Here, we show an efficient, transfer-free way to integrate centimeter-scale, single-crystal graphene, of a quality suitable for electronic devices, on an insulating SiO2 film. Starting with single-crystal graphene grown epitaxially on Ru(0001), a SiO2 film is grown under the graphene by stepwise intercalation of silicon and oxygen. Thin (∼1 nm) crystalline or thicker (∼2 nm) amorphous SiO2 has been produced. The insulating nature of the thick amorphous SiO2 is verified by transport measurements. The device-quality of the corresponding graphene was confirmed by the observation of Shubnikov-de Haas oscillations, an integer quantum Hall effect, and a weak antilocalization effect within in situ fabricated Hall bar devices. This work provides a reliable platform for applications of large-scale, high-quality graphene in electronics.
Objective：To analyze the component law of Chinese patent medicines for anti-influenza and develop new prescriptions for anti-influenza by unsupervised data mining methods. Methods： Chinese patent ...medicine recipes for anti-influenza were collected and recorded in the database, and then the correlation coefficient between herbs, core combinations of herbs and new prescriptions were analyzed by using modified mutual information, complex system entropy cluster and unsupervised hierarchical clustering, respectively. Results： Based on analysis of 126 Chinese patent medicine recipes, the frequency of each herb occurrence in these recipes, 54 frequently-used herb pairs, 34 core combinations were determined, and 4 new recipes for influenza were developed. Conclusion： Unsupervised data mining methods are able to mine the component law quickly and develop new prescriptions.
This paper is concerned with the bifurcation of a complex Swift-Hohenberg equation. The attractor bifurcation of the complex Swift-Hohenberg equation on a one- dimensional domain （0, L） is ...investigated. It is shown that the n-dimensional complex Swift-Hohenberg equation bifurcates from the trivial solution to an attractor under the Dirichlet boundary condition on a general domain and under a periodic boundary condition when the bifurcation parameter crosses some critical values. The stability property of the bifurcation attractor is analyzed.
When designing a mechanical product, how to determine its assembly tolerance specifications (ATS) and tolerance zone types (TZT) is a complex design problem, in which designers need to consider ...comprehensively the functional requirement, geometric feature, tolerance principle, and so on. Therefore, it has high requirements for designers. Meanwhile, the design and development of a complex assembly need to be done jointly by designers. This will cause difficulties for the overall coordination of tolerance design, which affects the quality and efficiency of product development. In order to reduce the uncertainty of ATS and TZT design, and to adapt to the requirements of digital design, a new reasoning algorithm for the automatic generation of ATS and TZT is presented. Polychromatic sets theory (PST) can provide a more formal approach to describe research objects and the relationships among them. Based on PST, this method establishes reasoning relation matrices to represent the relations among research objects, such as assembly feature, assembly constraint type, datum reference frame and tolerance zone type. Therefore, it can use a unified formal mathematical model to describe the whole reasoning process from assembly to ATS and TZT. This method realizes the systematization and computerization of ATS and TZT design, which can help designers to achieve the coordination and coherence of tolerance design. This method facilitates knowledge management and improves reasoning quality and efficiency. ATSs and TZTs generated by this method meet the functional requirements of product and are in accord with the tolerance standards in ISO/ASME. Furthermore, the method only requires a little geometric information and is consistent with the designers’ way of thinking, which shows good applicability for the practical design of ATS and TZT. Finally, the reasoning steps of ATSs and TZTs are demonstrated by means of an example.
► The systematization and computerization of ATS and TZT design is realized. ► Unified mathematical models are established to describe the reasoning process. ► The method enhances the clarity, uniformity and consistency in ATS and TZT design. ► It meets the requirements of “Top-down” design technique and accords with designer’s way of thinking.
To explore the intracellular mechanisms underlying the survival/differentiation effect of the glial cell line-derived neurotrophic factor (GDNF) on dopamine (DA) cells.
Midbrain slice culture and ...primary cell culture were established, and the cultures were divided into 3 groups: control group, GDNF group, and the phosphatidylinositol 3-kinase/Akt (PI3-K/Akt) pathway-inhibited group. Then the expression of tyrosine hydroxylase (TH) was detected by immunostaining as well as Western blotting.
GDNF treatment induced an increase in the number of TH-immunoreactive (ir) cells and the neurite number of TH-ir cells, as well as in the level of TH expression in cultures (Number of TH-ir cells in the slice culture: control group, 8.76+/-0.75; GDNF group, 18.63+/-0.95. Number of TH-ir cells and neurite number of TH-ir cells in cell culture: control group, 3.65+/-0.88 and 2.49+/-0.42; GDNF group, 6.01+/-0.43 and 4.89+/-0.46). Meanwhile, the stimulation of cultured cells with GDNF increased the phosphorylation of Akt, which is a downstream effector of PI3-K/Akt. The effects of GDNF were specifically blocked by the inhibitor of the PI3-K/Akt pathway, wortmannin (Number of TH-ir cells in slice culture: PI3-K/Akt pathway-inhibited group, 6.98+/-0.58. Number of TH-ir cells and neurite number of TH-ir cells in cell culture: PI3-K/Akt pathway-inhibited group, 3.79+/-0.62 and 2.50+/-0.25, respectively).
The PI3-K/Akt pathway mediates the survival/differentiation effect of GDNF on DA cells.
Background Aquired immune deficiency syndrome （AIDS） presents a challenge to medical researchers because of its unique pathological and clinical picture. The clinical data, particularly autopsy ...evidence, from China have failed to provide enough pathological and etiological evidence for AIDS diagnosis, which impairs the reliability of the diagnosis and our full understanding of the occurrence and development of AIDS complications. The purpose of this study was to investigate the imaging and pathologic characteristics of AIDS. Methods Autopsy, imaging and pathological data from 8 cases of AIDS were retrospectively analyzed. Routine CT scanning of different body parts was performed during their periods of hospitalization. Transverse CT scanning was conducted from the skull to the pelvis immediately after the occurrence of death. After routine formalin fixing, 7 cardevers were cross sectioned for autopsy in freezing state and 1 for gross autopsy. Tissues were obtained from each section and organs for pathological examinations. Results The autopsy data indicated the presence of parasitic infections, bacterial infections, fungal infections, and virus infections in AIDS patients. Pneumocystis pneumonia, pulmonary tuberculosis, coccobacteria pneumonia, Aspergillus pneumonia, cytomegaJovirus pneumonia, toxoplasma encephalitis, lymphoma and cerebrovascular diseases were found in these patients. Conclusions During the course of AIDS progression, the concurrent multiple infections as well as tumor development may resuJt in multiple organ pathological changes and clinically complex symptoms that further complicate the imaging and pathological manifestations, thus resulting in difficult differential diagnosis. A combination of imaging data and autopsy data can help to clarify the diagnosis.
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