Self-supporting noncovalent Choline Alginate/Tannic acid/Ag antibacterial films for strawberry preservation.

Packaging materials with peculiar antibacterial properties can shield off and inhibit microorganism proliferation, thus achieving packaging goals such as fresh-keeping, good hygiene, and biosafety. Especially, antibacterial films made of biocompatible substances have received wide attentions, which could effectively extend the shelf life, enhance food security, and guarantee economic benefits. Herein, a self-supporting hybrid antibacterial film was prepared based on non-covalently linked choline hydroxide (ChOH) and alginic acid (HAlg). Then tannic acid (TA) and silver ions were added to improve the mechanical and antimicrobial properties of this hybrid film. The rich hydroxyl groups from TA not only form multiple hydrogen bonds with ChAlg, but can also in situ reduce silver ions to silver nanoparticles, which were confirmed with various characterizations. In addition, the quantitative antibacterial test proved that the antibacterial rate was significantly improved after adding silver ions, reaching >60 %. In an actual storage test, we found that choline cation (Ch+) captured in antibacterial film by electrostatic interaction could achieve sustained release, i.e. sustainable bacteriostasis, and keep strawberries fresh for 48 h at room temperature. This work offers a new strategy for preparing antibacterial films via non-covalent weak interactions, explored an alternative antibacterial film for food packaging applications.

Magnetoencephalography reveals impaired sensory gating and change detection in older adults in the somatosensory system.

Brain electrophysiological responses can provide information about age-related decline in sensory-cognitive functions with high temporal accuracy. Studies have revealed impairments in early sensory gating and pre-attentive change detection mechanisms in older adults, but no magnetoencephalographic (MEG) studies have been undertaken into both non-attentive and attentive somatosensory functions and their relationship to ageing. Magnetoencephalography was utilized to record cortical somatosensory brain responses in young (20-28 yrs), middle-aged (46-56 yrs), and older adults (64-78 yrs) under active and passive somatosensory oddball conditions. A repeated standard stimulus was occasionally replaced by a deviant stimulus (p = .1), which was an electrical pulse on a different finger. We examined the amplitudes of M50 and M100 responses reflecting sensory gating, and later components reflecting change detection and attention shifting (M190 and M250 for the passive condition, and M200 and M350 for the active condition, respectively). Spatiotemporal cluster-based permutation tests revealed that older adults had significantly larger M100 component amplitudes than young adults for task-irrelevant stimuli in both passive and active condition. Older adults also showed a reduced M250 component and an altered M350 in response to deviant stimuli. The responses of middle-aged adults did not differ from those of younger adults, but this study should be repeated with a larger sample size. By demonstrating changes in both somatosensory gating and attentional shifting mechanisms, our findings extend previous research on the effects of ageing on pre-attentive and attentive brain functions.

Nanoscale ductile fracture and associated atomistic mechanisms in a body-centered cubic refractory metal.

Understanding the competing modes of brittle versus ductile fracture is critical for preventing the failure of body-centered cubic (BCC) refractory metals. Despite decades of intensive investigations, the nanoscale fracture processes and associated atomistic mechanisms in BCC metals remain elusive due to insufficient atomic-scale experimental evidence. Here, we perform in situ atomic-resolution observations of nanoscale fracture in single crystals of BCC Mo. The crack growth process involves the nucleation, motion, and interaction of dislocations on multiple 1/2 < 111 > {110} slip systems at the crack tip. These dislocation activities give rise to an alternating sequence of crack-tip plastic shearing, resulting in crack blunting, and local separation normal to the crack plane, leading to crack extension and sharpening. Atomistic simulations reveal the effects of temperature and strain rate on these alternating processes of crack growth, providing insights into the dislocation-mediated mechanisms of the ductile to brittle transition in BCC refractory metals.

A multi-omics approach identifies bHLH71-like as a positive regulator of yellowing leaf pepper mutants exposed to high-intensity light.

Light quality and intensity can have a significant impact on plant health and crop productivity. Chlorophylls and carotenoids are classes of plant pigments that are responsible for harvesting light energy and protecting plants from the damaging effects of intense light. Our understanding of the role played by plant pigments in light sensitivity has been aided by light-sensitive mutants that change colors upon exposure to light of variable intensity. In this study, we conducted transcriptomic, metabolomic, and hormone analyses on a novel yellowing mutant of pepper (yl1) to shed light on the molecular mechanism that regulates the transition from green to yellow leaves in this mutant upon exposure to high-intensity light. Our results revealed greater accumulation of the carotenoid precursor phytoene and the carotenoids phytofluene, antheraxanthin, and zeaxanthin in yl1 compared with wild-type plants under high light intensity. A transcriptomic analysis confirmed that enzymes involved in zeaxanthin and antheraxanthin biosynthesis were upregulated in yl1 upon exposure to high-intensity light. We also identified a single basic helix-loop-helix (bHLH) transcription factor, bHLH71-like, that was differentially expressed and positively correlated with light intensity in yl1. Silencing of bHLH71-like in pepper plants suppressed the yellowing phenotype and led to reduced accumulation of zeaxanthin and antheraxanthin. We propose that the yellow phenotype of yl1 induced by high light intensity could be caused by an increase in yellow carotenoid pigments, concurrent with a decrease in chlorophyll accumulation. Our results also suggest that bHLH71-like functions as a positive regulator of carotenoid biosynthesis in pepper.

DNA Nanobarrel-Based Drug Delivery for Paclitaxel and Doxorubicin.

Co-delivery of anticancer drugs and target agents by endogenous materials is an inevitable approach towards targeted and synergistic therapy. Employing DNA base pair complementarities, DNA nanotechnology exploits a unique nanostructuring method and has demonstrated its capacity for nanoscale positioning and templated assembly. Moreover, the water solubility, biocompatibility, and modifiability render DNA structure suitable candidate for drug delivery applications. We here report single-stranded DNA tail conjugated antitumor drug paclitaxel (PTX), and the co-delivery of PTX, doxorubicin and targeting agent mucin 1 (MUC-1) aptamer on a DNA nanobarrel carrier. We investigated the effect of tail lengths on drug release efficiencies and dual drug codelivery-enabled cytotoxicity. Owing to the rapidly developing field of structural DNA nanotechnology, functional DNA-based drug delivery is promising to achieve clinical therapeutic applications.

The effect of sad mood on early sensory event-related potentials to task-irrelevant faces.

It has been shown that the perceiver's mood affects the perception of emotional faces, but it is not known how mood affects preattentive brain responses to emotional facial expressions. To examine the question, we experimentally induced sad and neutral mood in healthy adults before presenting them with task-irrelevant pictures of faces while an electroencephalography was recorded. Sad, happy, and neutral faces were presented to the participants in an ignore oddball condition. Differential responses (emotional - neutral) for the P1, N170, and P2 amplitudes were extracted and compared between neutral and sad mood conditions. Emotional facial expressions modulated all the components, and an interaction effect of expression by mood was found for P1: an emotional modulation to happy faces, which was found in neutral mood condition, disappeared in sad mood condition. For N170 and P2, we found larger response amplitudes for both emotional faces, regardless of the mood. The results add to the previous behavioral findings showing that mood already affects low-level cortical feature encoding of task-irrelevant faces.

Pain modulates early sensory brain responses to task-irrelevant emotional faces.

BACKGROUND: Pain can have a significant impact on an individual's life, as it has both cognitive and affective consequences. However, our understanding of how pain affects social cognition is limited. Previous studies have shown that pain, as an alarm stimulus, can disrupt cognitive processing when focal attention is required, but whether pain also affects task-irrelevant perceptual processing remains unclear. METHODS: We examined the effect of laboratory-induced pain on event-related potentials (ERPs) to neutral, sad and happy faces before, during and after a cold pressor pain. ERPs reflecting different stages of visual processing (P1, N170 and P2) were analysed. RESULTS: Pain decreased the P1 amplitude for happy faces and increased the N170 amplitude for happy and sad faces compared to the pre-pain phase. The effect of pain on N170 was also observed in the post-pain phase. The P2 component was not affected by pain. CONCLUSIONS: Our results suggest that pain alters both featural (P1) and structural face-sensitive (N170) visual encoding of emotional faces, even when the faces are irrelevant to the task. While the effect of pain on initial feature encoding seemed to be disruptive and specific to happy faces, later processing stages showed long-lasting and increased activity for both sad and happy emotional faces. SIGNIFICANCE: The observed alterations in face perception due to pain may have consequences for real-life interactions, as fast and automatic encoding of facial emotions is important for social interactions.

Alterations in working memory maintenance of fearful face distractors in depressed participants: An ERP study.

Task-irrelevant threatening faces (e.g., fearful) are difficult to filter from visual working memory (VWM), but the difficulty in filtering non-threatening negative faces (e.g., sad) is not known. Depressive symptoms could also potentially affect the ability to filter different emotional faces. We tested the filtering of task-irrelevant sad and fearful faces by depressed and control participants performing a color-change detection task. The VWM storage of distractors was indicated by contralateral delay activity, a specific event-related potential index for the number of objects stored in VWM during the maintenance phase. The control group did not store sad face distractors, but they automatically stored fearful face distractors, suggesting that threatening faces are specifically difficult to filter from VWM in non-depressed individuals. By contrast, depressed participants showed no additional consumption of VWM resources for either the distractor condition or the non-distractor condition, possibly suggesting that neither fearful nor sad face distractors were maintained in VWM. Our control group results confirm previous findings of a threat-related filtering difficulty in the normal population while also suggesting that task-irrelevant non-threatening negative faces do not automatically load into VWM. The novel finding of the lack of negative distractors within VWM storage in participants with depressive symptoms may reflect a decreased overall responsiveness to negative facial stimuli. Future studies should investigate the mechanisms underlying distractor filtering in depressed populations.

Pseudocatalytic Hydrogels with Intrinsic Antibacterial and Photothermal Activities for Local Treatment of Subcutaneous Abscesses and Breast Tumors.

The intimate relationship between bacteria and tumors has triggered a lot of activities in the development and design of bioactive materials to concurrently respond to antitumor and antibacterial demands. Herein, a pseudocatalytic hydrogel (AM-I@Agar) with intrinsic antibacterial and photothermal activities, synthesized by incorporating prefabricated amylose-iodine nanoparticles into low-melting-point agarose hydrogel, is explored as a bioactive agent for local treatment of subcutaneous abscesses and breast tumors. The AM-I@Agar hydrogel depicts the ability of pseudocatalytic O2 generation from H2 O2 to alleviate hypoxia. Meanwhile, the AM-I@Agar hydrogel exhibits temperature self-regulation features, beneficial for avoiding thermal injury during photothermal therapy owing to thermochromic properties. Upon local injection into a subcutaneous abscess, methicillin-resistant Staphylococcus aureus is effectively eliminated by the AM-I@Agar hydrogel, and complete skin recovery is achieved in 8 d, demonstrating much better antibacterial effects compared with penicillin, a small-molecule antibiotic. AM-I/5-FU@Agar hydrogel, obtained after loading 5-fluorouracil (5-FU), significantly inhibits tumors in both normal 4T1 tumor-bearing mice and MRSA-infected 4T1 tumor-bearing mice models via a synergistic photothermal-chemo effect, and shows treatment efficiency superior to that achieved with photothermal therapy or 5-FU alone. This work provides a concept for the design and development of bioactive agents for potential management of bacteria-associated cancer.

Decreased intersubject synchrony in dynamic valence ratings of sad movie contents in dysphoric individuals.

Emotional reactions to movies are typically similar between people. However, depressive symptoms decrease synchrony in brain responses. Less is known about the effect of depressive symptoms on intersubject synchrony in conscious stimulus-related processing. In this study, we presented amusing, sad and fearful movie clips to dysphoric individuals (those with elevated depressive symptoms) and control participants to dynamically rate the clips' valences (positive vs. negative). We analysed both the valence ratings' mean values and intersubject correlation (ISC). We used electrodermal activity (EDA) to complement the measurement in a separate session. There were no group differences in either the EDA or mean valence rating values for each movie type. As expected, the valence ratings' ISC was lower in the dysphoric than the control group, specifically for the sad movie clips. In addition, there was a negative relationship between the valence ratings' ISC and depressive symptoms for sad movie clips in the full sample. The results are discussed in the context of the negative attentional bias in depression. The findings extend previous brain activity results of ISC by showing that depressive symptoms also increase variance in conscious ratings of valence of stimuli in a mood-congruent manner.

Magnetoencephalography Responses to Unpredictable and Predictable Rare Somatosensory Stimuli in Healthy Adult Humans.

Mismatch brain responses to unpredicted rare stimuli are suggested to be a neural indicator of prediction error, but this has rarely been studied in the somatosensory modality. Here, we investigated how the brain responds to unpredictable and predictable rare events. Magnetoencephalography responses were measured in adults frequently presented with somatosensory stimuli (FRE) that were occasionally replaced by two consecutively presented rare stimuli [unpredictable rare stimulus (UR) and predictable rare stimulus (PR); p = 0.1 for each]. The FRE and PR were electrical stimulations administered to either the little finger or the forefinger in a counterbalanced manner between the two conditions. The UR was a simultaneous electrical stimulation to both the forefinger and the little finger (for a smaller subgroup, the UR and FRE were counterbalanced for the stimulus properties). The grand-averaged responses were characterized by two main components: one at 30-100 ms (M55) and the other at 130-230 ms (M150) latency. Source-level analysis was conducted for the primary somatosensory cortex (SI) and the secondary somatosensory cortex (SII). The M55 responses were larger for the UR and PR than for the FRE in both the SI and the SII areas and were larger for the UR than for the PR. For M150, both investigated areas showed increased activity for the UR and the PR compared to the FRE. Interestingly, although the UR was larger in stimulus energy (stimulation of two fingers at the same time) and had a larger prediction error potential than the PR, the M150 responses to these two rare stimuli did not differ in source strength in either the SI or the SII area. The results suggest that M55, but not M150, can possibly be associated with prediction error signals. These findings highlight the need for disentangling prediction error and rareness-related effects in future studies investigating prediction error signals.

Timely and atomic-resolved high-temperature mechanical investigation of ductile fracture and atomistic mechanisms of tungsten.

Revealing the atomistic mechanisms for the high-temperature mechanical behavior of materials is important for optimizing their properties for service at high-temperatures and their thermomechanical processing. However, due to materials microstructure's dynamic recovery and the absence of available in situ techniques, the high-temperature deformation behavior and atomistic mechanisms of materials are difficult to evaluate. Here, we report the development of a microelectromechanical systems-based thermomechanical testing apparatus that enables mechanical testing at temperatures reaching 1556 K inside a transmission electron microscope for in situ investigation with atomic-resolution. With this unique technique, we first uncovered that tungsten fractures at 973 K in a ductile manner via a strain-induced multi-step body-centered cubic (BCC)-to-face-centered cubic (FCC) transformation and dislocation activities within the strain-induced FCC phase. Both events reduce the stress concentration at the crack tip and retard crack propagation. Our research provides an approach for timely and atomic-resolved high-temperature mechanical investigation of materials at high-temperatures.

Electrical brain activity and facial electromyography responses to irony in dysphoric and non-dysphoric participants.

We studied irony comprehension and emotional reactions to irony in dysphoric and control participants. Electroencephalography (EEG) and facial electromyography (EMG) were measured when spoken conversations were presented with pictures that provided either congruent (non-ironic) or incongruent (ironic) contexts. In a separate session, participants evaluated the congruency and valence of the stimuli. While both groups rated ironic stimuli funnier than non-ironic stimuli, the control group rated all the stimuli funnier than the dysphoric group. N400-like activity, P600, and EMG activity indicating smiling were larger after the ironic stimuli than the non-ironic stimuli for both groups. Further, in the dysphoric group the irony modulation was evident in the electrode cluster over the right hemisphere, while no such difference in lateralization was observed in the control group. The results suggest a depression-related alteration in the P600 response associated to irony comprehension, but no alterations were found in emotional reactivity specifically related to irony.

Tailoring Au Films at the Atomic Scale with an Electron Beam Tweezer.

A thin, clean pristine Au film created in a transmission electron microscope chamber was tailored by an electron beam. Various kinds of nanopatterns, including hexagonal holes and dumbbell-like patterns, were fabricated by different doses of the electron beam. A high-quality series of in situ images were recorded to explore the irradiation mechanism. The electron-matter collision enabled the electron beam to act as a tweezer to arrange atoms into a specified pattern.

Continuous "Snowing" Thermotherapeutic Graphene.

Finding the best applications of graphene, and the continuous and scalable preparation of graphene with high quality and high purity, are still two major challenges. Herein, a "pulse-etched" microwave-induced "snowing" (PEMIS) process is developed for continuous and scalable preparation of high-quality and high-purity graphene directly in the gas phase, which is found to have excellent thermotherapeutic effects. The obtained graphene exhibits small size (≈180 nm), high quality, low oxygen content, and high purity, together with a high gas-solid conversion efficiency of ≈10.46%. Considering the intrinsic characteristics of this high-purity and small-sized biocompatible graphene, in particular the low-frequency microwave absorption property as well as the good thermal transformation ability, a graphene-based combination therapeutic system is demonstrated for microwave thermal therapy (MTT) for the first time, exhibiting a high tumor ablation rate of ≈86.7%. This is different from the principle of ions vibrating in a confined space used by current MTT sensitization materials. Not limited to this application, it is foreseen that this PEMIS-based high-quality graphene will allow the search for further suitable applications of graphene.

Event-Related Potentials to Changes in Sound Intensity Demonstrate Alterations in Brain Function Related to Depression and Aging.

Measures of the brain's automatic electrophysiological responses to sounds represent a potential tool for identifying age- and depression-related neural markers. However, these markers have rarely been studied related to aging and depression within one study. Here, we investigated auditory event-related potentials (ERPs) in the brain that may show different alterations related to aging and depression. We used an oddball condition employing changes in sound intensity to investigate: (i) sound intensity dependence; (ii) sensory gating; and (iii) change detection, all within a single paradigm. The ERPs of younger (18-40 years) and older (62-80 years) depressed female participants and age-matched non-depressed participants were measured. Intensity dependence was examined as the difference between N1 responses to repeated high- and low-intensity sounds, sensory gating as N1 responses to rare and repeated sounds, and change detection as indexed by the mismatch negativity (MMN). We found that intensity dependence was greater in older participants than younger ones, indicating effects related to aging but not to depression. For sensory gating, we found depression- and age-related alterations as increased N1 responses. No group differences were found for MMN. Although a sensory gating deficit was expected in older adults, this study is the first to demonstrate age-related overexcitability in sound intensity dependency. The results indicate that automatic brain responses to sound intensity changes are suitable for studying age- and depression-related neural markers but may not be sensitive enough to differentiate the effects of aging and depression.

Automatic Processing of Changes in Facial Emotions in Dysphoria: A Magnetoencephalography Study.

It is not known to what extent the automatic encoding and change detection of peripherally presented facial emotion is altered in dysphoria. The negative bias in automatic face processing in particular has rarely been studied. We used magnetoencephalography (MEG) to record automatic brain responses to happy and sad faces in dysphoric (Beck's Depression Inventory ≥ 13) and control participants. Stimuli were presented in a passive oddball condition, which allowed potential negative bias in dysphoria at different stages of face processing (M100, M170, and M300) and alterations of change detection (visual mismatch negativity, vMMN) to be investigated. The magnetic counterpart of the vMMN was elicited at all stages of face processing, indexing automatic deviance detection in facial emotions. The M170 amplitude was modulated by emotion, response amplitudes being larger for sad faces than happy faces. Group differences were found for the M300, and they were indexed by two different interaction effects. At the left occipital region of interest, the dysphoric group had larger amplitudes for sad than happy deviant faces, reflecting negative bias in deviance detection, which was not found in the control group. On the other hand, the dysphoric group showed no vMMN to changes in facial emotions, while the vMMN was observed in the control group at the right occipital region of interest. Our results indicate that there is a negative bias in automatic visual deviance detection, but also a general change detection deficit in dysphoria.

Heterostructure TiO2 polymorphs design and structure adjustment for photocatalysis.

Atomic composite-structure materials play an important role in energy generation and storage application fields for their advanced performance. Constructing heterostructured semiconductors is a promising strategy to devise photocatalytic systems with high activity. However, most studied hererostructures are those semiconductors with different materials formed by multi-steps, researches on in-situ formed hererostructure originated from the same precursor are few reported, and the effects of different structure ratios on photocatalytic performance are ambiguous. Here, according to in-situ temperature X-ray diffraction and transmission electron microscope techniques, a nano-sized in-situ formed heterostructure of TiO2 semiconductors with anatase and TiO2-B crystalline structures were designed, their structure ratios were adjusted, the heterostructure interface and photocatalytic reaction mechanism were also detected. Results show that high-quality heterojunction and optimum structure ratios have vital influence on photocatalytic performance, there is an obvious synergetic effect between anatase and TiO2-B structure, degradation reactions on methyl orange (MO) under ultraviolet light irradiation prove that the highest activity toward MO removal can be obtained for material with 82.5% anatase structure.