Advances in Nanomaterials for Sustainable Gas Separation and Storage: Focus on Clathrate Hydrates.

ConspectusClathrate hydrates, also known as gas hydrates, are a type of inclusion compound formed in highly developed nanoporous lattice spaces created by water molecules, where gas molecules such as CO2, H2, CH4, and other low-molecular-weight liquid molecules are trapped. The nanoporous cage formed by water molecules serves as the "host", while the trapped gas or low-molecular-weight liquid molecules such as tetrahydrofuran act as "guests". Early on, clathrate hydrates drew attention as a potential replacement for conventional natural gas due to their natural gas hydrate form, which contains natural gases as guests and exists in permafrost or sea floors. Recently, based on the unique physicochemical properties of clathrate hydrates, efforts are being made to utilize synthetic clathrate hydrates in various separation processes such as post- and pre-combustion CO2 capture, H2 storage, natural gas storage and transportation, wastewater desalination, and more. While it is undeniable that clathrate hydrates are based on principles that are beneficial for the separation and storage of gas molecules, there are several challenges that must be addressed for their practical application. These challenges include (i) the limitation of gas storage capacity due to the confined size of nanoporous cages, (ii) the relatively high-pressure and low-temperature thermodynamic storage conditions typically required for clathrate hydrate formation, and (iii) slow formation kinetics and low gas hydrate conversion, which are also essential issues that need to be resolved for the meaningful implementation of clathrate hydrates. In this Account, we aim to introduce recent noteworthy research findings, including those from our research team, focusing on addressing these challenges. We explored the untapped potential of clathrate hydrates by bridging the gap between macroscopic and microscopic properties. This has led to breakthroughs in sustainable gas separation and storage applications. By revealing the hidden nature of these hydrates, we have effectively mitigated their inherent limitations, setting the stage for more feasible and efficient H2 storage solutions through the introduction of hydrogen-natural gas blends to clathrate hydrates. Additionally, we have demonstrated the tuning effect on all naturally formed hydrate structures, offering new insights into their underlying properties and macroscopic behavior. Furthermore, our research has proposed a highly efficient hydrate-based pre-combustion CO2 capture approach that leverages porous media with appropriate wettability and considers the implications of microstructure properties. This emphasizes the crucial connection between nano-structure and macroscopic properties, underscoring the significance of understanding their interplay for economic feasibility. We believe that our efforts to unveil the hidden nature of gas hydrates provide strategies to address challenges and lay the groundwork for practical applications.

Sex differences in binge drinking-related higher morning cortisol levels and in prospective association with future alcohol intake.

AIMS: Peripheral cortisol represents one biological measure of the hypothalamic-pituitary-adrenal (HPA) axis, a significant component of the stress system, which is altered by chronic alcohol consumption. However, whether heavy alcohol use affects the HPA axis differentially between the sexes and whether basal cortisol levels are a biomarker of prospective alcohol intake is unknown. METHODS: We recruited light moderate (LM) and binge-heavy (BH) drinkers of alcohol (n = 118). Repeated fasting morning cortisol levels were studied over a 2-hour period to assess basal levels while participants underwent a neuroimaging scan. RESULTS: Significantly higher average cortisol levels in BH compared to LM groups across four timepoints were observed (P < .018). Overall sex differences were observed with women showing higher initial cortisol levels at the first timepoint with a blunted decrease over the morning relative to men (P < .003). Average morning cortisol differentially predicted prospective future 30-day daily reports of alcohol consumption by sex and group, such that LM males had a positive significant relationship and BH males had a negative non-significant relationship between cortisol and drinking. CONCLUSIONS: Findings indicate that morning plasma cortisol is upregulated in the BH vs. LM group. Although females had higher initial morning cortisol levels, BH males showed a dysregulated negative relationship between stress and binge drinking in contrast to the LM group. Future work should further investigate the role of cortisol and other stress hormones as biomarkers of problematic drinking behaviors in men and women.

Irregular Autonomic Modulation Predicts Risky Drinking and Altered Ventromedial Prefrontal Cortex Response to Stress in Alcohol Use Disorder.

AIMS: Autonomic dysfunction has been associated with risky drinking and alcohol use disorder (AUD). Although autonomic nervous system (ANS) activity has been attributed to the ventromedial prefrontal cortex (VmPFC)-limbic-striatal regions, the specific role of ANS disruption in AUD and its association with these regions remain unclear. Using functional magnetic resonance imaging (fMRI) and concurrent electrocardiogram (ECG), the current study examined neural correlates of ANS activity in AUD and its role in AUD pathology. METHODS: Demographically matched 20 AUD patients and 20 social drinkers (SD) completed an fMRI task involving repeated exposure to stress, alcohol-cue and neutral-relaxing images in a block design. Based on the known VmPFC-limbic-striatal functions involved in emotions, reward and the ANS, we performed a regions of interest (ROI) analysis to examine the associations between ANS activity and neural responses in the VmPFC, amygdala, and ventral striatum. RESULTS: Across conditions, AUD patients showed significantly higher levels of overall heart rate (HR) and approximate entropy (ApEn) compared to SD (Ps < 0.05). In all participants, increased HR was associated with greater drinking volume (P < 0.05). In addition, higher ApEn levels were associated with greater drinking volume (P < 0.05) and decreased right VmPFC response to stress (P < 0.05). DISCUSSION: Our findings demonstrate ANS disruption in AUD indexed by high overall HR and ApEn. The association between ApEn and rVmPFC response suggests that ApEn may play a role in modulating drinking via interactions with neural regions of emotion regulation. These findings provide insight into patterns of ANS disruption and their relevance to AUD pathology.

Alcohol withdrawal symptoms predict corticostriatal dysfunction that is reversed by prazosin treatment in alcohol use disorder.

Chronic alcohol use increases risk of alcohol withdrawal symptoms (AW) and disrupts stress biology and resilient coping, thereby promoting excessive alcohol intake. Chronic alcohol intake and multiple alcohol detoxifications are known to impair brain medial prefrontal cortex (mPFC) and striatal functioning, regions involved in regulating stress, craving and alcohol intake. In two related studies, we examined whether AW predicts this functional brain pathology and whether Prazosin versus Placebo treatment may reverse these effects. In Study 1, patients with Alcohol Use Disorder (AUD) (N = 45) with varying AW levels at treatment entry were assessed to examine AW effects on corticostriatal responses to stress, alcohol cue and neutral visual images with functional magnetic resonance imaging (fMRI). In Study 2, 23 AUD patients entering a 12-week randomised controlled trial (RCT) of Prazosin, an alpha1 adrenergic antagonist that decreased withdrawal-related alcohol intake in laboratory animals, participated in two fMRI sessions at pretreatment and also at week 9-10 of chronic treatment (Placebo: N = 13; Prazosin: N = 10) to assess Prazosin treatment effects on alcohol-related cortico-striatal dysfunction. Study 1 results indicated that higher AW predicted greater disruption in brain mPFC and striatal response to stress and alcohol cues (p < 0.001, family-wise error [FWE] correction) and also subsequently greater heavy drinking days (HDD) in early treatment (p < 0.01). In Study 2, Prazosin versus Placebo treatment reversed mPFC-striatal dysfunction (p < 0.001, FWE), which in turn predicted fewer drinking days (p < 0.01) during the 12-week treatment period. These results indicate that AW is a significant predictor of alcohol-related prefrontal-striatal dysfunction, and Prazosin treatment reversed these effects that in turn contributed to improved alcohol treatment outcomes.

Differential effects of recent versus past traumas on mood, social support, binge drinking, emotional eating and BMI, and on neural responses to acute stress.

Traumatic stress is associated with risk of psychiatric and physical illnesses. However, the differential and separable effects of past versus recent traumas on maladaptive coping and neural responses are not known. We conducted two studies to assess separate and combined effects of cumulative recent and past trauma on health outcomes (study 1) and on neural responses to acute stress exposure in a subsample of individuals (study 2). Study 1 assessed a large cohort of 677 community adults cross-sectionally, and findings indicated that both high recent (within the last 12 months) and past trauma (prior to the last twelve months) were associated with more physical and psychological symptoms, including increased depression (all p's < .05). However, recent trauma alone was associated with higher problematic alcohol use, a greater maximum number of alcohol drinks consumed, greater emotional eating scores, higher state and trait anxiety scores, and poorer lifestyle habits (all p's < .05). Past trauma alone was associated with higher BMI, decreased social support, and a lower average cortisol relative to ACTH ratio (all p's < .02). Study 2 involving a functional brain scan on a subsample (N = 75) indicated greater recent trauma was associated with a hyperactive response in the ventromedial prefrontal cortex (VmPFC) to neutral-relaxed exposure, but blunted VmPFC response to acute stress exposure (p < .05: whole brain corrected-WBC). By contrast, high past trauma was associated with a hyper-sensitized neural response to stress in the cortico-limbic-striatal regions (p < .05, WBC) critical for reward and emotion processing. Together, these findings suggest differential neurobehavioral and health effects of cumulative past versus recent trauma exposure.

Dynamic neural activity during stress signals resilient coping.

Active coping underlies a healthy stress response, but neural processes supporting such resilient coping are not well-known. Using a brief, sustained exposure paradigm contrasting highly stressful, threatening, and violent stimuli versus nonaversive neutral visual stimuli in a functional magnetic resonance imaging (fMRI) study, we show significant subjective, physiologic, and endocrine increases and temporally related dynamically distinct patterns of neural activation in brain circuits underlying the stress response. First, stress-specific sustained increases in the amygdala, striatum, hypothalamus, midbrain, right insula, and right dorsolateral prefrontal cortex (DLPFC) regions supported the stress processing and reactivity circuit. Second, dynamic neural activation during stress versus neutral runs, showing early increases followed by later reduced activation in the ventrolateral prefrontal cortex (VLPFC), dorsal anterior cingulate cortex (dACC), left DLPFC, hippocampus, and left insula, suggested a stress adaptation response network. Finally, dynamic stress-specific mobilization of the ventromedial prefrontal cortex (VmPFC), marked by initial hypoactivity followed by increased VmPFC activation, pointed to the VmPFC as a key locus of the emotional and behavioral control network. Consistent with this finding, greater neural flexibility signals in the VmPFC during stress correlated with active coping ratings whereas lower dynamic activity in the VmPFC also predicted a higher level of maladaptive coping behaviors in real life, including binge alcohol intake, emotional eating, and frequency of arguments and fights. These findings demonstrate acute functional neuroplasticity during stress, with distinct and separable brain networks that underlie critical components of the stress response, and a specific role for VmPFC neuroflexibility in stress-resilient coping.

Humans with obesity have disordered brain responses to food images during physiological hyperglycemia.

Blood glucose levels influence brain regulation of food intake. This study assessed the effect of mild physiological hyperglycemia on brain response to food cues in individuals with obesity (OB) versus normal weight individuals (NW). Brain responses in 10 OB and 10 NW nondiabetic healthy adults [body mass index: 34 (3) vs. 23 (2) kg/m2, means (SD), P < 0.0001] were measured with functional MRI (blood oxygen level-dependent contrast) in combination with a two-step normoglycemic-hyperglycemic clamp. Participants were shown food and nonfood images during normoglycemia (~95 mg/dl) and hyperglycemia (~130 mg/dl). Plasma glucose levels were comparable in both groups during the two-step clamp ( P = not significant). Insulin and leptin levels were higher in the OB group compared with NW, whereas ghrelin levels were lower (all P < 0.05). During hyperglycemia, insula activity showed a group-by-glucose level effect. When compared with normoglycemia, hyperglycemia resulted in decreased activity in the hypothalamus and putamen in response to food images ( P < 0.001) in the NW group, whereas the OB group exhibited increased activity in insula, putamen, and anterior and dorsolateral prefrontal cortex (aPFC/dlPFC; P < 0.001). These data suggest that OB, compared with NW, appears to have disruption of brain responses to food cues during hyperglycemia, with reduced insula response in NW but increased insula response in OB, an area involved in food perception and interoception. In a post hoc analysis, brain activity in obesity appears to be associated with dysregulated motivation (striatum) and inappropriate self-control (aPFC/dlPFC) to food cues during hyperglycemia. Hyperstimulation for food and insensitivity to internal homeostatic signals may favor food consumption to possibly play a role in the pathogenesis of obesity.

Gender differences in neural correlates of stress-induced anxiety.

Although gender differences have been identified as a crucial factor for understanding stress-related anxiety and associated clinical disorders, the neural mechanisms underlying these differences remain unclear. To explore gender differences in the neural correlates of stress-induced anxiety, the current study used functional magnetic resonance imaging to examine brain responses in 96 healthy men and women with commensurable levels of trait anxiety as they engaged in a personalized guided imagery paradigm to provoke stress and neutral-relaxing experiences. During the task, a significant gender main effect emerged, with men displaying greater responses in the caudate, cingulate gyrus, midbrain, thalamus, and cerebellum. In contrast, women showed greater responses in the posterior insula, temporal gyrus, and occipital lobe. Additionally, a significant anxiety ratings × gender interaction from whole-brain regression analyses was observed in the dorsomedial prefrontal cortex, left inferior parietal lobe, left temporal gyrus, occipital gyrus, and cerebellum (P < 0.05, whole-brain family-wise error corrected), with positive associations between activity in these regions and stress-induced anxiety in women, but negative associations in men, indicating that men and women differentially use neural resources when experiencing stress-induced anxiety. The findings suggest that in response to stress, there is a greater use of the medial prefrontal-parietal cortices in experiencing subjective anxiety in women, while decreased use of this circuit was associated with increased subjective anxiety states in men. The current study has implications for understanding gender-specific differences in stress-induced anxiety and vulnerability to stress-related clinical disorders, and for developing more effective treatment strategies tailored to each gender. © 2016 Wiley Periodicals, Inc.

Fabrication of a vertically-stacked passive-matrix micro-LED array structure for a dual color display.

We report a color tunable display consisting of two passive-matrix micro-LED array chips. The device has combined vertically stacked blue and green passive-matrix LED array chips sandwiched by a transparent bonding material. We demonstrate that vertically stacked blue and green micro-pixels are independently controllable with operation of four color modes. Moreover, the color of each pixel is tunable in the entire wavelength from the blue to green region (450 nm - 540 nm) by applying pulse-width-modulation bias voltage. This study is meaningful in that a dual color micro-LED array with a vertically stacked subpixel structure is realized.

Peripheral and prefrontal stress system markers and risk of relapse in alcoholism.

Previous research has shown that hyperactivation in ventral medial prefrontal cortex (VmPFC) and rostral anterior cingulate cortex (rACC) and high cortisol to corticotrophin ratio (cort:ACTH ratio) during neutral-relaxed states predict relapse in alcohol-dependent (AD) patients. Other studies have shown that VmPFC/rACC deactivation and blunted cortisol release to stress and alcohol cues are predictive of time to relapse and relapse severity. However, no previous study has assessed the relationship between these markers of central and peripheral nervous system dysfunction in AD participants and their potential joint effects on relapse risk. Forty early abstinent, treatment engaged AD patients underwent a laboratory experiment with exposure to neutral, alcohol and stress cues and a separate functional magnetic resonance imaging scan with similar cue exposure. Neutral-relaxed state cort:ACTH ratio was significantly associated with VmPFC hyperreactivity to neutral-relaxing cues, and also with hypoactivation in response to alcohol and stress cues in AD patients. Basal heart rate, neutral cort:ACTH ratio and neutral VmPFC hyperreactivty were each associated with risk of relapse. However, abnormal VmPFC activation and elevated cort:ACTH ratio overlap in predicting risk for relapse, and dysfunctional VmPFC response was the sole significant predictor of odds of relapse in a joint model of relapse risk. These findings suggest that the cort:ACTH ratio may serve as a peripheral marker of VmPFC brain dysfunction, while aberrant VmPFC responses need further evaluation as a potential biomarker of alcohol relapse risk in clinical outcome studies.

Ag nanoparticles-embedded surface plasmonic InGaN-based solar cells via scattering and localized field enhancement.

Ag nanoparticles are embedded in intentionally etched micro-circle p-GaN holes by means of a thermal agglomeration process to enhance the light absorption efficiency in InGaN/GaN multi-quantum-well (MQW) solar cells. The Ag nanoparticles are theoretically and experimentally verified to generate the plasmon light scattering and the localized field enhancement near the MQW absorption layer. The external quantum efficiency enhancement at a target wavelength region is demonstrated by matching the plasmon resonance of Ag nanoparticles, resulting in a Jsc improvement of 9.1%. Furthermore, the Ag-nanoparticle-embedded InGaN solar cell is effectively fabricated considering the carrier extraction that more than 70% of F.F. and 2.2 V of high Voc are simultaneously attained.

Neural Correlates and Connectivity Underlying Stress-Related Impulse Control Difficulties in Alcoholism.

BACKGROUND: Stress triggers impulsive and addictive behaviors, and alcoholism has been frequently associated with increased stress sensitivity and impulse control problems. However, neural correlates underlying the link between alcoholism and impulsivity in the context of stress in patients with alcohol use disorders (AUD) have not been well studied. METHODS: This study investigated neural correlates and connectivity patterns associated with impulse control difficulties in abstinent AUD patients. Using functional magnetic resonance imaging, brain responses of 37 AUD inpatients, and 37 demographically matched healthy controls were examined during brief individualized imagery trials of stress, alcohol cue, and neutral-relaxing conditions. Stress-related impulsivity was measured using a subscale score of impulse control problems from Difficulties in Emotion Regulation Scale. RESULTS: Impulse control difficulties in AUD patients were significantly associated with hypo-active response to stress in the ventromedial prefrontal cortex (VmPFC), right caudate, and left lateral PFC (LPFC) compared to the neutral condition (p < 0.01, whole-brain corrected). These regions were used as seed regions to further examine the connectivity patterns with other brain regions. With the VmPFC seed, AUD patients showed reduced connectivity with the anterior cingulate cortex compared to controls, which are core regions of emotion regulation, suggesting AUD patients' decreased ability to modulate emotional response under distressed state. With the right caudate seed, patients showed increased connectivity with the right motor cortex, suggesting increased tendency toward habitually driven behaviors. With the left LPFC seed, decreased connectivity with the dorsomedial PFC (DmPFC), but increased connectivity with sensory and motor cortices were found in AUD patients compared to controls (p < 0.05, whole-brain corrected). Reduced connectivity between the left LPFC and DmPFC was further associated with increased stress-induced anxiety in AUD patients (p < 0.05, with adjusted Bonferroni correction). CONCLUSIONS: Hypo-active response to stress and altered connectivity in key emotion regulatory regions may account for greater stress-related impulse control problems in alcoholism.

Size-controlled InGaN/GaN nanorod LEDs with an ITO/graphene transparent layer.

We introduce ITO on graphene as a current-spreading layer for separated InGaN/GaN nanorod LEDs for the purpose of passivation-free and high light-extraction efficiency. Transferred graphene on InGaN/GaN nanorods effectively blocks the diffusion of ITO atoms to nanorods, facilitating the production of transparent ITO/graphene contact on parallel-nanorod LEDs, without filling the air gaps, like a bridge structure. The ITO/graphene layer sufficiently spreads current in a lateral direction, resulting in uniform and reliable light emission observed from the whole area of the top surface. Using KOH treatment, we reduce series resistance and reverse leakage current in nanorod LEDs by recovering the plasma-damaged region. We also control the size of the nanorods by varying the KOH treatment time and observe strain relaxation via blueshift in electroluminescence. As a result, bridge-structured LEDs with 8 min of KOH treatment show 15 times higher light-emitting efficiency than with 2 min of KOH treatment.

Brain correlates and functional connectivity linking stress, autonomic dysregulation, and alcohol motivation.

High stress is a key risk factor for alcohol use disorder (AUD) and often accompanied by physiological dysregulation including autonomic nervous system (ANS) disruptions. However, neural mechanisms underlying drinking behaviors associated with stress and ANS disruptions remain unclear. The current study aims to understand neural correlates of stress, ANS disruptions, and subsequent alcohol intake in social drinkers with risky drinking. Using functional magnetic resonance imaging (fMRI), we investigated brain and heart rate (HR) autonomic responses during brief exposure to stress, alcohol, and neutral cues utilizing a well-validated, individualized imagery paradigm in 48 social drinkers of which 26 reported high-risk drinking (HD) while 22 reported low-risk drinking (LD) patterns. Results indicated that HD individuals showed stress and ANS disruptions with increased basal HR, stress-induced craving, and decreased brain response to stress exposure in frontal-striatal regions including the ventromedial prefrontal cortex (VmPFC), anterior cingulate cortex, striatum, insula, and temporal gyrus. Furthermore, whole-brain correlation analysis indicated that greater basal HR was associated with hypoactive VmPFC, but hyperactive medulla oblongata (MOb) responses during stress, with an inverse association between activity in the VmPFC and Mob (whole-brain corrected (WBC), p < 0.05). Functional connectivity with the MOb as a seed to the whole brain indicated that HD versus LD had decreased functional connectivity between the VmPFC and MOb during stress (WBC, p < 0.05). In addition, those with more compromised functional connectivity between the VmPFC and MOb during stress consumed greater amount of alcohol beverage during an experimental alcohol taste test conducted on a separate day, as well as in their self-reported weekly alcohol intake. Together, these results indicate that stress-related, dysfunctional VmPFC control over brain regions of autonomic arousal contributes to greater alcohol motivation and may be a significant risk factor for hazardous alcohol use in non-dependent social drinkers. Findings also suggest that restoring VmPFC integrity in modulating autonomic arousal during stress may be critical for preventing the development of AUD.

Neural Correlates of Stress and Alcohol Cue-Induced Alcohol Craving and of Future Heavy Drinking: Evidence of Sex Differences.

OBJECTIVE: Stress and alcohol cue reactivity are associated with poor treatment outcomes in alcohol use disorder (AUD), but sex-specific neural correlates of stress and alcohol cue-induced craving compared with neutral cue-induced craving and of heavy drinking outcomes in AUD have not been examined. Thus, this study prospectively examined these associations and assessed sex differences. METHODS: Treatment-seeking adults with AUD (N=77; 46 men and 31 women) completed a functional MRI task involving stress, alcohol, and neutral cue exposure with repeated assessments of alcohol craving. Most of these participants (N=72; 43 men and 29 women) then participated in an 8-week standardized behavioral AUD treatment program, during which the percentage of heavy drinking days was assessed. RESULTS: Significant increases in both stress and alcohol cue-induced craving relative to neutral cue-induced craving were observed, with a greater alcohol-neutral contrast in craving relative to the stress-neutral contrast among men and equivalent stress-neutral and alcohol-neutral contrasts in craving among women. Whole-brain voxel-based regression analyses showed craving-associated hyperactivation in the neutral condition, but hypoactive prefrontal (ventromedial and lateral prefrontal, supplementary motor, and anterior cingulate regions) and striatal responses during exposure to stressful images (stress-neutral contrast) and alcohol cues (alcohol-neutral contrast), with significant sex differences. Additionally, a higher percentage of heavy drinking days was associated with hypoactivation of the subgenual anterior cingulate cortex and the bed nucleus of the stria terminalis in the stress-neutral contrast among women, hyperactivation of the hypothalamus in the stress-neutral contrast among men, and hyperactivation of the hippocampus in the alcohol-neutral contrast among men. CONCLUSIONS: Sex differences in stress- and alcohol cue-induced responses in the cortico-striatal-limbic network related to subjective alcohol craving and to heavy drinking indicated that distinct brain circuits underlie alcohol use outcomes in women and men. These findings underscore the need for sex-specific therapeutics to address this neural dysfunction effectively.

Altered brain and physiological stress responses in early psychosis.

Stress is proposed to be a crucial factor in the onset and presentation of psychosis. The early stage of psychosis provides a window into how stress interacts with the emergence of psychosis. Yet, how people with early psychosis respond to stress remains unclear. The current study examined how stress responses (brain, physiological, self-report) differ in early psychosis. Forty participants (20 early psychosis [EP], 20 healthy controls [HC]) completed a stress task in the scanner that involved viewing stressful and neutral-relaxing images. Physiological responses (cortisol, heart rate) and self-report of stress were also assessed. Region of Interest analyses were conducted with brain regions previously shown to be activated during the stress task (amygdala, hippocampus, striatum, hypothalamus, prefrontal cortex [dorsolateral, ventrolateral, medial orbital]). Linear mixed models were used to test for effects of group (EP, HC) and emotion (stress, neutral-relaxing). HC had higher hippocampus activation to stress versus neutral-relaxing conditions while EP did not show a difference (group x emotion interaction, p = 0.04). There were also significant main effects of group with EP having higher amygdala activation (p = 0.01), ventrolateral prefrontal cortex activation (vlPFC, p = 0.03), self-report of stress (p = 0.01), and heart rate (p < 0.001). Our study found preliminary evidence that people with early psychosis showed heightened response to stressful and non-threatening situations, across multiple levels of stress responses. Our findings suggest a novel perspective on stress alterations in early psychosis and highlight the importance of considering both stressful and non-stressful situations.

Low-calorie diet-induced weight loss is associated with altered brain connectivity and food desire in obesity.

OBJECTIVE: The main objective of this study is to better understand the effects of diet-induced weight loss on brain connectivity in response to changes in glucose levels in individuals with obesity. METHODS: A total of 25 individuals with obesity, among whom 9 had a diagnosis of type 2 diabetes, underwent functional magnetic resonance imaging (fMRI) scans before and after an 8-week low-calorie diet. We used a two-step hypereuglycemia clamp approach to mimic the changes in glucose levels observed in the postprandial period in combination with task-mediated fMRI intrinsic connectivity distribution (ICD) analysis. RESULTS: After the diet, participants lost an average of 3.3% body weight. Diet-induced weight loss led to a decrease in leptin levels, an increase in hunger and food intake, and greater brain connectivity in the parahippocampus, right hippocampus, and temporal cortex (limbic-temporal network). Group differences (with vs. without type 2 diabetes) were noted in several brain networks. Connectivity in the limbic-temporal and frontal-parietal brain clusters inversely correlated with hunger. CONCLUSIONS: A short-term low-calorie diet led to a multifaceted body response in patients with obesity, with an increase in connectivity in the limbic-temporal network (emotion and memory) and hormone and eating behavior changes that may be important for recovering the weight lost.

Neural correlates of stress and favorite-food cue exposure in adolescents: a functional magnetic resonance imaging study.

Adolescence is a critical period of neurodevelopment for stress and appetitive processing, as well as a time of increased vulnerability to stress and engagement in risky behaviors. This study was conducted to examine brain activation patterns during stress and favorite-food-cue experiences relative to a neutral-relaxing condition in adolescents. Functional magnetic resonance imaging was employed using individualized script-driven guided imagery to compare brain responses with such experiences in 43 adolescents. Main effects of condition and gender were found, without a significant gender-by-condition interaction. Stress imagery, relative to neutral, was associated with activation in the caudate, thalamus, left hippocampus/parahippocampal gyrus, midbrain, left superior/middle temporal gyrus, and right posterior cerebellum. Appetitive imagery of favorite food was associated with caudate, thalamus, and midbrain activation compared with the neutral-relaxing condition. To understand neural correlates of anxiety and craving, subjective (self-reported) measures of stress-induced anxiety and favorite-food-cue-induced craving were correlated with brain activity during stress and appetitive food-cue conditions, respectively. High self-reported stress-induced anxiety was associated with hypoactivity in the striatum, thalamus, hippocampus, and midbrain. Self-reported favorite-food-cue-induced craving was associated with blunted activity in cortical-striatal regions, including the right dorsal and ventral striatum, medial prefrontal cortex, motor cortex, and left anterior cingulate cortex. These findings in adolescents indicate the activation of predominantly subcortical-striatal regions in the processing of stressful and appetitive experiences and link hypoactive striatal circuits to self-reported stress-induced anxiety and cue-induced favorite-food craving.

Size-controlled InGaN/GaN nanorod array fabrication and optical characterization.

We demonstrate a cost-effective top-down approach for fabricating InGaN/GaN nanorod arrays using a wet treatment process in a KOH solution. The average diameter of the as-etched nanorods was effectively reduced from 420 nm to 180 nm. The spatial strain distribution was then investigated by measuring the high-resolution cathodoluminescence directly on top of the nanorods. The smaller nanorods showed a higher internal quantum efficiency and lower potential fluctuation, which can subsequently be exploited for high-efficiency photonic devices.

Binge drinking is associated with higher cortisol and lower hippocampal and prefrontal gray matter volume: Prospective association with future alcohol intake.

Background: Cortisol is a significant driver of the biological stress response that is potently activated by acute alcohol intake and increased with binge drinking. Binge drinking is associated with negative social and health consequences and risk of developing alcohol use disorder (AUD). Both cortisol levels and AUD are also associated with changes in hippocampal and prefrontal regions. However, no previous research has assessed structural gray matter volume (GMV) and cortisol concurrently to examine BD effects on hippocampal and prefrontal GMV and cortisol, and their prospective relationship to future alcohol intake. Methods: Individuals who reported binge drinking (BD: N = 55) and demographically matched non-binge moderate drinkers (MD: N = 58) were enrolled and scanned using high-resolution structural MRI. Whole brain voxel-based morphometry was used to quantify regional GMV. In a second phase, 65% of the sample volunteered to participate in prospective daily assessment of alcohol intake for 30 days post-scanning. Results: Relative to MD, BD showed significantly higher cortisol and smaller GMV in regions including hippocampus, dorsal lateral prefrontal cortex (dlPFC), prefrontal and supplementary motor, primary sensory and posterior parietal cortex (FWE, p < 0.05). GMV in bilateral dlPFC and motor cortices were negatively associated with cortisol levels, and smaller GMV in multiple PFC regions was associated with more subsequent drinking days in BD. Conclusion: These findings indicate neuroendocrine and structural dysregulation associated with BD relative to MD. Notably, BD-associated lower GMV regions were those involved in stress, memory and cognitive control, with lower GMV in cognitive control and motor regions also predicting higher levels of future alcohol intake in BD.