Two Birds with One Stone: Broadband Electromagnetic Wave Absorption and Anticorrosion Performance in 2-18 GHz for Prussian Blue Analog Derivatives Aimed for Practical Applications.

Nowadays, the exploration of electromagnetic (EM) wave absorbers with anticorrosion to improve the survivability and environmental adaptability of military targets in the harsh environments is becoming an attractive and unavoidable challenge. Herein, through modulation of the metal composition in the precursors, the core@shell structure Prussian blue analog-derived NiCo@C, CoFe@C, NiFe@C, and NiCoFe@C are obtained with excellent EM wave absorption performance. As for NiCoFe@C, ascribed to the coupling effect of the dual magnetic alloy, a minimum reflection loss (RL) of -47.6 dB and an effective absorption bandwidthof 5.83 GHz are realized, which cover the whole Ku-band. Meanwhile, four absorbers display the lower corrosion current density (10-4 -10-6 A cm-2 ) and larger polarization resistance (104 -106  Ω) under acid, neutral, and alkaline corrosion conditions over uninterrupted 30 days. Furthermore, due to the spatial barrier effect and the passivation effect of the graphitic carbon shell , the continuous salt spray test has little effect on RL performance and inconspicuously changes the surface morphologies of coating, demonstrating its excellent bifunctional performance. This work lays the foundation for the development of metal-organic frameworks-derived materials with both anticorrosion and EM wave absorption performance.

Functional Abnormality of the Executive Control Network in Individuals With Obesity During Delay Discounting.

Individuals with obesity (OB) prefer immediate rewards of food intake over the delayed reward of healthy well-being achieved through diet management and physical activity, compared with normal-weight controls (NW). This may reflect heightened impulsivity, an important factor contributing to the development and maintenance of obesity. However, the neural mechanisms underlying the greater impulsivity in OB remain unclear. Therefore, the current study employed functional magnetic resonance imaging with a delay discounting (DD) task to examine the association between impulsive choice and altered neural mechanisms in OB. During decision-making in the DD task, OB compared with NW had greater activation in the dorsolateral prefrontal cortex (DLPFC) and posterior parietal cortex, which was associated with greater discounting rate and weaker cognitive control as measured with the Three-Factor Eating Questionnaire (TFEQ). In addition, the association between DLPFC activation and cognitive control (TFEQ) was mediated by discounting rate. Psychophysiological interaction analysis showed decreased connectivity of DLPFC-inferior parietal cortex (within executive control network [ECN]) and angular gyrus-caudate (ECN-reward) in OB relative to NW. These findings reveal that the aberrant function and connectivity in core regions of ECN and striatal brain reward regions underpin the greater impulsivity in OB and contribute to abnormal eating behaviors.

Brain Connectivity, and Hormonal and Behavioral Correlates of Sustained Weight Loss in Obese Patients after Laparoscopic Sleeve Gastrectomy.

The biological mediators that support cognitive-control and long-term weight-loss after laparoscopic sleeve gastrectomy (LSG) remain unclear. We measured peripheral appetitive hormones and brain functional-connectivity (FC) using magnetic-resonance-imaging with food cue-reactivity task in 25 obese participants at pre, 1 month, and 6 month after LSG, and compared with 30 normal weight controls. We also used diffusion-tensor-imaging to explore whether LSG increases brain structural-connectivity (SC) of regions involved in food cue-reactivity. LSG significantly decreased BMI, craving for high-calorie food cues, ghrelin, insulin, and leptin levels, and increased self-reported cognitive-control of eating behavior. LSG increased FC between the right dorsolateral prefrontal cortex (DLPFC) and the pregenual anterior cingulate cortex (pgACC) and increased SC between DLPFC and ACC at 1 month and 6 month after LSG. Reduction in BMI correlated negatively with increased FC of right DLPFC-pgACC at 1 month and with increased SC of DLPFC-ACC at 1 month and 6 month after LSG. Reduction in craving for high-calorie food cues correlated negatively with increased FC of DLPFC-pgACC at 6 month after LSG. Additionally, SC of DLPFC-ACC mediated the relationship between lower ghrelin levels and greater cognitive control. These findings provide evidence that LSG improved functional and structural connectivity in prefrontal regions, which contribute to enhanced cognitive-control and sustained weight-loss following surgery.

Connectome-Based Prediction of Optimal Weight Loss Six Months After Bariatric Surgery.

Despite bariatric surgery being the most effective treatment for obesity, a proportion of subjects have suboptimal weight loss post-surgery. Therefore, it is necessary to understand the mechanisms behind the variance in weight loss and identify specific baseline biomarkers to predict optimal weight loss. Here, we employed functional magnetic resonance imaging (fMRI) with baseline whole-brain resting-state functional connectivity (RSFC) and a multivariate prediction framework integrating feature selection, feature transformation, and classification to prospectively identify obese patients that exhibited optimal weight loss at 6 months post-surgery. Siamese network, which is a multivariate machine learning method suitable for small sample analysis, and K-nearest neighbor (KNN) were cascaded as the classifier (Siamese-KNN). In the leave-one-out cross-validation, the Siamese-KNN achieved an accuracy of 83.78%, which was substantially higher than results from traditional classifiers. RSFC patterns contributing to the prediction consisted of brain networks related to salience, reward, self-referential, and cognitive processing. Further RSFC feature analysis indicated that the connection strength between frontal and parietal cortices was stronger in the optimal versus the suboptimal weight loss group. These findings show that specific RSFC patterns could be used as neuroimaging biomarkers to predict individual weight loss post-surgery and assist in personalized diagnosis for treatment of obesity.

Resting activity of the hippocampus and amygdala in obese individuals predicts their response to food cues.

Obese individuals exhibit brain functional abnormalities in multiple regions implicated in reward/motivation, emotion/memory, homeostatic regulation, and executive control when exposed to food cues and during rest. However, it remains unclear whether abnormal brain responses to food cues might account for or relate to their abnormal activity in resting state. This information would be useful for understanding the neural mechanisms behind hyperactive responses to food cues, a critical marker of obesity. Resting-state functional magnetic resonance imaging (RS-fMRI) and a cue-reactivity fMRI task with high- (HiCal) and low-caloric (LoCal) food cues were employed to investigate brain baseline activity and food cue-induced activation differences in 44 obese participants (OB), in 37 overweight participants (OW), and in 37 normal weight (NW) controls. One-way analyses of variance showed there was a group difference in the left hippocampus/amygdala activity during resting state and during food-cue stimulation (pFWE < 0.05); post-hoc tests showed the OB group had both greater basal activity and greater food cue-induced activation than the OW and NW groups; OW had higher activity in the hippocampus/amygdala than the NW group, which was only significant during resting state. In the OB group, resting-state activity in the left hippocampus/amygdala was positively correlated with activation induced by HiCal food cues, and both of these measures correlated with body mass index (BMI). Mediation analysis showed that the relationship between BMI and hippocampus/amygdala response to HiCal food cues was mediated by their resting-state activity. These findings suggest a close association between obesity and brain functional abnormality in the hippocampus/amygdala. They also indicate that resting-state activity in the hippocampus/amygdala may impact these regions' responses to food cues.

Functional constipation is associated with alterations in thalamo-limbic/parietal structural connectivity.

BACKGROUND: Functional constipation (FCon) is a common functional gastrointestinal disorder (FGID) with a high prevalence in clinical practice. Previous studies have identified that FCon is associated with functional and structural alterations in the primary brain regions involved in emotional arousal processing, sensory processing, somatic/motor-control, and self-referential processing. However, whether FCon is associated with abnormal structural connectivity (SC) among these brain regions remains unclear. METHODS: We selected the brain regions with functional and structural abnormalities as seed regions and employed diffusion tensor imaging (DTI) with probabilistic tractography to investigate SC changes in 29 patients with FCon and 31 healthy controls (HC). KEY RESULTS: Results showed lower fractional anisotropy (FA) in the fibers connecting the thalamus, a region involved in sensory processing, with the amygdala (AMY), hippocampal gyrus (HIPP), precentral (PreCen) and postcentral gyrus (PostCen), supplementary motor area (SMA) and precuneus in patients with FCon compared with HC. FCon had higher mean diffusivity (MD) and radial diffusivity (RD) in the thalamus connected to the AMY and HIPP. In addition, FCon had significantly increased RD of the thalamus-SMA tract. Sensation of incomplete evacuation was negatively correlated with FA of the thalamus-PostCen and thalamus-HIPP tracts, and there was a negative correlation between difficulty of defecation and FA of the thalamus-SMA tract. CONCLUSIONS AND INFERENCES: These findings reflected that FCon is associated with alterations in SC between the thalamus and limbic/parietal cortex, highlighting the integrative role of the thalamus in brain structural network.

Laparoscopic sleeve gastrectomy improves brain connectivity in obese patients.

OBJECTIVE: Obese individuals have shown functional abnormalities in frontal-limbic regions, and bariatric surgery is an effective treatment for morbid obesity. The aim of the study was to investigate how bariatric surgery modulates brain regional activation and functional connectivity (FC) to food cues, and whether the underlying structural connectivity (SC) alterations contribute to these functional changes as well as behavioral changes. METHODS: A functional magnetic resonance imaging cue-reactivity task with high- (HiCal) and low-calorie (LoCal) food pictures and diffusion tensor imaging (DTI) with deterministic tractography were used to investigate brain reactivity, FC and SC in 28 obese participants tested before and 1 month after laparoscopic sleeve gastrectomy (LSG). Twenty-two obese controls (Ctr) without surgery were also tested at baseline and 1 month later. RESULTS: LSG significantly decreased right dorsolateral prefrontal cortex (DLPFC) activation to HiCal versus LoCal cues and increased FC between DLPFC and ventral anterior cingulate cortex (vACC), which are regions involved in self-regulation of feeding behaviors. LSG also increased SC between DLPFC and ACC as quantified by fractional anisotropy. Increases in SC and FC between DLPFC and ACC were associated with greater reductions in BMI, and SC changes were positively correlated with FC changes. Increased SC between right DLPFC and ACC mediated the relationship between reduced BMI and increased right DLPFC-vACC FC; likewise, increases in right DLPFC-vACC FC mediated the relationship between increased right DLPFC-ACC SC and reduced BMI. CONCLUSION: LSG might induce weight loss in part by increasing SC and FC between DLPFC and ACC, and thus strengthening top-down control over food intake.