Abstract
The diagnosis of functional dyspepsia (FD) presently relies on the self-reported symptoms. This study aimed to determine the potential of functional brain network features as biomarkers for ...the identification of FD patients. Firstly, the functional brain Magnetic Resonance Imaging data were collected from 100 FD patients and 100 healthy subjects, and the functional brain network features were extracted by the independent component analysis. Then, a support vector machine classifier was established based on these functional brain network features to discriminate FD patients from healthy subjects. Features that contributed substantially to the classification were finally identified as the classifying features. The results demonstrated that the classifier performed pretty well in discriminating FD patients. Namely, the accuracy of classification was 0.84 ± 0.03 in cross-validation set and 0.80 ± 0.07 in independent test set, respectively. A total of 15 connections between the subcortical nucleus (the thalamus and caudate) and sensorimotor cortex, parahippocampus, orbitofrontal cortex were finally determined as the classifying features. Furthermore, the results of cross-brain atlas validation showed that these classifying features were quite robust in the identification of FD patients. In summary, the current findings suggested the potential of using machine learning method and functional brain network biomarkers to identify FD patients.
The aberrant static functional connectivity of brain network has been widely investigated in patients with functional constipation (FCon). However, the dynamics of brain functional connectivity in ...FCon patients remained unknown. This study aimed to detect the brain dynamics of functional connectivity states and network topological organizations of FCon patients and investigate the correlations of the aberrant brain dynamics with symptom severity. Eighty‐three FCon patients and 80 healthy subjects (HS) were included in data analysis. The spatial group independent component analysis, sliding‐window approach, k‐means clustering, and graph‐theoretic analysis were applied to investigate the dynamic temporal properties and coupling patterns of functional connectivity states, as well as the time‐variation of network topological organizations in FCon patients. Four reoccurring functional connectivity states were identified in k‐means clustering analysis. Compared to HS, FCon patients manifested the lower occurrence rate and mean dwell time in the state with a complex connection between default mode network and cognitive control network, as well as the aberrant anterior insula–cortical coupling patterns in this state, which were significantly correlated with the symptom severity. The graph‐theoretic analysis demonstrated that FCon patients had higher sample entropy at the nodal efficiency of anterior insula than HS. The current findings provided dynamic perspectives for understanding the brain connectome of FCon and laid the foundation for the potential treatment of FCon based on brain connectomics.
The current study provided dynamic perspectives for understanding the brain connectome of patients with functional constipation. The results demonstrated the disruptions of dynamic functional connectivity patterns in patients with functional constipation from the respects of the absence of default mode network–cognitive control network connection states, abnormality of anterior insula–cortical coupling patterns, as well as atypical dynamics of regional topological organizations.
Tai Chi has been proven to be a safe and effective assistant therapy for healthcare and disease treatment. However, whether the adjuvant therapeutic effect of Tai Chi is general or disease-oriented ...remains uncertain. This trial focuses on exploring the specific and nonspecific effects of Tai Chi and its potential central responses. The results will deepen our understanding of the characteristics of Tai Chi exercise for adjuvant therapeutic effects and promote its application in the clinic. In this neuroimaging trial, 40 functional constipation (FC) patients and 40 healthy subjects (HS) will be recruited and will receive 10 weeks of Tai Chi exercise. The motor function, respiratory function, stool-related symptoms, quality of life, and emotional state of the participants will be evaluated at the baseline, the 5-week Tai Chi practice, and the end of practice. The potential changes in the heart rate variability and the cerebral function will be recorded by the 24 h dynamic electrocardiogram at the baseline and the functional magnetic resonance imaging at the end of practice. The possible correlations among the clinical variables, the heart rate variability, and the cerebral activity alterations in FC patients and HS will be analyzed. The healthcare and therapeutic effects of Tai Chi exercise might consist of the specific and nonspecific effects. This study provides not only a new perspective for understanding Tai Chi but also a new approach for investigating the mind-body exercise. This trial was registered in the Chinese Clinical Trial Registry (http://www.chictr.org.cn/showproj.aspx?proj=33243) on 28 November 2018 (registration number: ChiCTR1800019781; protocol version number: V1.0). This trial is currently in the stage of recruiting patients. The first patient was included on 1 December 2018. To date, 18 FC patients and 20 HS have been included. Recruitment will be completed in December 2020.
Using neuroimaging techniques to explore the central mechanism of acupuncture gains increasing attention, but the quality control of acupuncture-neuroimaging study remains to be improved. We searched ...the PubMed Database during 1995 to 2014. The original English articles with neuroimaging scan performed on human beings were included. The data involved quality control including the author, sample size, characteristics of the participant, neuroimaging technology, and acupuncture intervention were extracted and analyzed. The rigorous inclusion and exclusion criteria are important guaranty for the participants’ homogeneity. The standard operation process of acupuncture and the stricter requirement for acupuncturist play significant role in quality control. More attention should be paid to the quality control in future studies to improve the reproducibility and reliability of the acupuncture-neuroimaging studies.
PET/PET-CT is an important technique to investigate the central mechanism of acupuncture in vivo. This article collected original research papers with keywords of “Acupuncture,” “PET,” “PET/CT,” and ...“Positron emission tomography” in PubMed and CNKI databases from January 2003 to December 2018. As a result, a total of 43 articles were included. Based on the literature analyses, we found that (1) reasonable arrangement of the operation process and the choice of appropriate acupuncture intervention time is conducive to a better interpretation of acupuncture-PET/PET-CT mechanism and (2) the selection of participants, sample size, acupuncture intervention, and experimental conditions would affect study results. Therefore, effective quality control is an important way to ensure the repeatability of research results.
Pure magnesium exhibits poor ductility owing to pyramidal Formula: see text dislocation transformations to immobile structures, making this lowest-density structural metal unusable for many ...applications where it could enhance energy efficiency. We show why magnesium can be made ductile by specific dilute solute additions, which increase the Formula: see text cross-slip and multiplication rates to levels much faster than the deleterious Formula: see text transformation, enabling both favorable texture during processing and continued plastic straining during deformation. A quantitative theory establishes the conditions for ductility as a function of alloy composition in very good agreement with experiments on many existing magnesium alloys, and the solute-enhanced cross-slip mechanism is confirmed by transmission electron microscopy observations in magnesium-yttrium. The mechanistic theory can quickly screen for alloy compositions favoring conditions for high ductility and may help in the development of high-formability magnesium alloys.
Abstract
Simultaneously enhancing strength and ductility of metals and alloys has been a tremendous challenge. Here, we investigate a CoCuFeNiPd high-entropy alloy (HEA), using a combination of Monte ...Carlo method, molecular dynamic simulation, and density-functional theory calculation. Our results show that this HEA is energetically favorable to undergo short-range ordering (SRO), and the SRO leads to a pseudo-composite microstructure, which surprisingly enhances both the ultimate strength and ductility. The SRO-induced composite microstructure consists of three categories of clusters: face-center-cubic-preferred (FCCP) clusters, indifferent clusters, and body-center-cubic-preferred (BCCP) clusters, with the indifferent clusters playing the role of the matrix, the FCCP clusters serving as hard fillers to enhance the strength, while the BCCP clusters acting as soft fillers to increase the ductility. Our work highlights the importance of SRO in influencing the mechanical properties of HEAs and presents a fascinating route for designing HEAs to achieve superior mechanical properties.
The conversion of methane to more valuable chemicals is one of the most intensively studied topics in catalysis. The direct conversion of methane is attractive because the process is simple, but ...unfortunately its products are chemicals that are more reactive than methane. The current status of this research field is discussed with an emphasis on C–H bond activation and future challenges.
Equiatomic FCC CrCoNi, VCoNi and CrCoNiFeMn exhibit distinctly different deformation mechanisms where twinning is prevalent in CrCoNi and CrCoNiFeMn, but not in VCoNi. Extant density-functional ...theory (DFT) calculations show that all 3 alloys possess similarly low/negative intrinsic stacking fault energies (SFEs) and thus high twinnability in random-solute states, which obviously contradicts experimental observations. Here, the mean and local generalized SFE-lines (γ-lines) are systematically determined using DFT in all 3 alloys with special quasirandom structure (SQS) and Monte Carlo (MC) simulation optimized structures. Linear elasticity with DFT-based γ-lines predicts wide core separations and twinnabilities higher than elemental FCC metals in all 3 alloys with SQS. During MC simulations, chemical short range ordering (SRO) is formed, with VCoNi exhibiting the strongest SRO, followed by CrCoNi and CrCoNiFeMn. SRO always raises the mean intrinsic SFE relative to that in base SQS configurations. The average increase scales linearly with the magnitude of the SRO, resulting in moderate, large and drastic increases in CrCoNiFeMn, CrCoNi and VCoNi, respectively. Furthermore, SRO has strong effects on the intrinsic and extrinsic SFEs, but weaker effects on the unstable SFEs, leading to disparate dislocation and twinning behaviour. In SRO-saturated states, CrCoNi and CrCoNiFeMn retain high twinnability comparable to Ag, while VCoNi has narrow core separations similar to Al and twinnability lower than all elemental FCC metals. The DFT-based γ-lines and mechanics-based prediction not only reveal SRO effects on GSFE, dislocation and twinning, but also shed light on the physical origin of the different deformation mechanisms in these alloys.
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Magnesium is a lightweight structural metal but it exhibits low ductility-connected with unusual, mechanistically unexplained, dislocation and plasticity phenomena-which makes it difficult to form ...and use in energy-saving lightweight structures. We employ long-time molecular dynamics simulations utilizing a density-functional-theory-validated interatomic potential, and reveal the fundamental origins of the previously unexplained phenomena. Here we show that the key 〈c + a〉 dislocation (where 〈c + a〉 indicates the magnitude and direction of slip) is metastable on easy-glide pyramidal II planes; we find that it undergoes a thermally activated, stress-dependent transition to one of three lower-energy, basal-dissociated immobile dislocation structures, which cannot contribute to plastic straining and that serve as strong obstacles to the motion of all other dislocations. This transition is intrinsic to magnesium, driven by reduction in dislocation energy and predicted to occur at very high frequency at room temperature, thus eliminating all major dislocation slip systems able to contribute to c-axis strain and leading to the high hardening and low ductility of magnesium. Enhanced ductility can thus be achieved by increasing the time and temperature at which the transition from the easy-glide metastable dislocation to the immobile basal-dissociated structures occurs. Our results provide the underlying insights needed to guide the design of ductile magnesium alloys.
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