A calibration-free c-VEP based BCI employing narrow-band random sequences

Objective.Code-modulated visual evoked potential (c-VEP) based brain-computer interfaces (BCIs) exhibit high encoding efficiency. Nevertheless, the majority of c-VEP based BCIs necessitate an initial training or calibration session, particularly when the number of targets expands, which impedes the practicality. To address this predicament, this study introduces a calibration-free c-VEP based BCI employing narrow-band random sequences.Approach.For the encoding method, a series of random sequences were generated within a specific frequency band. The c-VEP signals were subsequently elicited through the application of on-type grid flashes that were modulated by these sequences. For the calibration-free decoding algorithm, filter-bank canonical correlation analysis (FBCCA) was utilized with the reference templates generated from the original sequences. Thirty-five subjects participated into an online BCI experiment. The performances of c-VEP based BCIs utilizing narrow-band random sequences with frequency bands of 15-25 Hz (NBRS-15) and 8-16 Hz (NBRS-8) were compared with that of a steady-state visual evoked potential (SSVEP) based BCI within a frequency range of 8-15.8 Hz.Main results.The offline analysis results demonstrated a substantial correlation between the c-VEPs and the original narrow-band random sequences. After parameter optimization, the calibration-free system employing the NBRS-15 frequency band achieved an average information transfer rate (ITR) of 78.56 ± 37.03 bits/min, which exhibited no significant difference compared to the performance of the SSVEP based system when utilizing FBCCA. The proposed system achieved an average ITR of 102.1 ± 57.59 bits/min in a simulation of a 1000-target BCI system.Significance.This study introduces a novel calibration-free c-VEP based BCI system employing narrow-band random sequences and shows great potential of the proposed system in achieving a large number of targets and high ITR.

Optimizing Visual Stimulation Paradigms for User-Friendly SSVEP-Based BCIs

In steady-state visual evoked potential (SSVEP)-based brain-computer interface (BCI) systems, traditional flickering stimulation patterns face challenges in achieving a trade-off in both BCI performance and visual comfort across various frequency bands. To investigate the optimal stimulation paradigms with high performance and high comfort for each frequency band, this study systematically compared the characteristics of SSVEP and user experience of different stimulation paradigms with a wide stimulation frequency range of 1-60 Hz. The findings suggest that, for a better balance between system performance and user experience, ON and OFF grid stimuli with a Weber contrast of 50% can be utilized as alternatives to traditional flickering stimulation paradigms in the frequency band of 1-25 Hz. In the 25-35 Hz range, uniform flicker stimuli with the same 50% contrast are more suitable. In the higher frequency band, traditional uniform flicker stimuli with a high 300% contrast are preferred. These results are significant for developing high performance and user-friendly SSVEP-based BCI systems.

[The clinical significance of lateral pelvic sentinel lymph node biopsy using indocyanine green fluorescence navigation in laparoscopic lateral pelvic lymph node dissection]

Objectives: This study aims to explore the clinical significance of lateral pelvic sentinel lymph node biopsy (SLNB) using indocyanine green (ICG) fluorescence navigation in laparoscopic lateral pelvic lymph node dissection (LLND) and evaluate the accuracy and feasibility of this technique to predict the status of lateral pelvic lymph nodes (LPLNs). Methods: The clinical and pathological characteristics, surgical outcomes, lymph node findings and perioperative complications of 16 rectal cancer patients who underwent SLNB using ICG fluorescence navigation in laparoscopic LLND in the Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College during April 2017 and October 2022 were retrospectively collected and analyzed. The patients did not receive preoperative neoadjuvant radiotherapy and presented with LPLNs but without LPLN enlargement (MRI showed the maximum short axes of the LPLNs were ≥5 mm and <10 mm at first visit). Results: All 16 patients were successfully performed SLNB using ICG fluorescence navigation in laparoscopic LLND. Three patients underwent bilateral LLND and 13 patients underwent unilateral LLND. The lateral pelvic sentinel lymph nodes (SLNs) were clearly fluorescent before dissection in 14 patients and the detection rate of SLNs for these patients was 87.5%. Lateral pelvic SLN metastasis was diagnosed in 2 patients and negative results were found in 12 patients by frozen pathological examinations. Among the 14 patients in whom lateral pelvic SLNs were detected, the dissected lateral pelvic non-SLNs were all negative. All dissected LPLNs were negative in two patients without fluorescent lateral pelvic SLNs. The specificity, sensitivity, negative predictive value, and accuracy was 85.7%, 100%, 100%, and 100%, respectively. Conclusions: This study indicates that lateral pelvic SLNB using ICG fluorescence navigation shows promise as a safe and feasible procedure with good accuracy. This technique may replace preventive LLND for locally advanced lower rectal cancer.

An Ultrasensitive Ti3 C2 Tx MXene-based Soft Contact Lens for Continuous and Nondestructive Intraocular Pressure Monitoring

Wearable soft contact lens sensors for continuous and nondestructive intraocular pressure (IOP) monitoring are highly desired as glaucoma and postoperative myopia patients grow, especially as the eyestrain crowd increases. Herein, a smart closed-loop system is presented that combines a Ti3 C2 Tx MXene-based soft contact lens (MX-CLS) sensor, wireless data transmission units, display, and warning components to realize continuous and nondestructive IOP monitoring/real-time display. The fabricated MX-CLS device exhibits an extremely high sensitivity of 7.483 mV mmHg-1 , good linearity on silicone eyeballs, excellent stability under long-term pressure-release measurement, sufficient transparency with 67.8% transmittance under visible illumination, and superior biocompatibility with no discomfort when putting the MX-CLS sensor onto the Rabbit eyes. After integrating with the wireless module, users can realize real-time monitoring and warning of IOP via smartphones, the demonstrated MX-CLS device together with the IOP monitoring/display system opens up promising platforms for Ti3 C2 Tx materials as the base for multifunctional contact lens-based sensors and continuous and nondestructive IOP measurement system.

An open dataset for human SSVEPs in the frequency range of 1-60 Hz

A steady-state visual evoked potential (SSVEP)-based brain-computer interface (BCI) system relies on the photic driving response to effectively elicit characteristic electroencephalogram (EEG) signals. However, traditional visual stimuli mainly adopt high-contrast black-and-white flickering stimulations, which are easy to cause visual fatigue. This paper presents an SSVEP dataset acquired at a wide frequency range from 1 to 60 Hz with an interval of 1 Hz using flickering stimuli under two different modulation depths. This dataset contains 64-channel EEG data from 30 healthy subjects when they fixated on a single flickering stimulus. The stimulus was rendered on an LCD display with a refresh rate of 240 Hz. Initially, the dataset was rigorously validated through comprehensive data analysis to investigate SSVEP responses and user experiences. Subsequently, BCI performance was evaluated through offline simulations of frequency-coded and phase-coded BCI paradigms. This dataset provides comprehensive and high-quality data for studying and developing SSVEP-based BCI systems.

A high-frequency SSVEP-BCI system based on a 360 Hz refresh rate

Objective. Steady-state visual evoked potential (SSVEP) based brain-computer interfaces (BCIs) often struggle to balance user experience and system performance. To address this challenge, this study employed stimuli in the 55-62.8 Hz frequency range to implement a 40-target BCI speller that offered both high-performance and user-friendliness.Approach. This study proposed a method that presents stable multi-target stimuli on a monitor with a 360 Hz refresh rate. Real-time generation of stimulus matrix and stimulus rendering was used to ensure stable presentation while reducing the computational load. The 40 targets were encoded using the joint frequency and phase modulation method, offline and online BCI experiments were conducted on 16 subjects using the task discriminant component analysis algorithm for feature extraction and classification.Main results. The online BCI system achieved an average accuracy of 88.87% ± 3.05% and an information transfer rate of 51.83 ± 2.77 bits min-1under the low flickering perception condition.Significance. These findings suggest the feasibility and significant practical value of the proposed high-frequency SSVEP BCI system in advancing the visual BCI technology.

Flexible multichannel electrodes for acute recording in nonhuman primates

Flexible electrodes have demonstrated better biocompatibility than rigid electrodes in relieving tissue encapsulation and long-term recording. Nonhuman primates are closer to humans in their brains' structural and functional properties, thus making them more suitable than rodents as animal models for potential clinical usage. However, the application of flexible electrodes on nonhuman primates has rarely been reported. In the present study, a flexible multichannel electrode array for nonhuman primates was developed and implemented for extracellular recording in behaving monkeys. To minimize the window of durotomy for reducing possible risks, a guide-tube-compatible implantation solution was designed to deliver the flexible electrodes through the dura into the cortex. The proposed structure for inserting flexible electrodes was characterized ex vivo and validated in vivo. Furthermore, acute recording of multichannel flexible electrodes for the primates was performed. The results showed that the flexible electrodes and implantation method used in this study meet the needs of extracellular recording in nonhuman primates. Task-related neuronal activities with a high signal-to-noise ratio of spikes demonstrated that our whole device is currently a minimally invasive and clinically viable approach for extracellular recording.

A wearable group-synchronized EEG system for multi-subject brain-computer interfaces

Objective

The multi-subject brain-computer interface (mBCI) is becoming a key tool for the analysis of group behaviors. It is necessary to adopt a neural recording system for collaborative brain signal acquisition, which is usually in the form of a fixed wire.

Approach

In this study, we designed a wireless group-synchronized neural recording system that supports real-time mBCI and event-related potential (ERP) analysis. This system uses a wireless synchronizer to broadcast events to multiple wearable EEG amplifiers. The simultaneously received broadcast signals are marked in data packets to achieve real-time event correlation analysis of multiple targets in a group.

Main results

To evaluate the performance of the proposed real-time group-synchronized neural recording system, we conducted collaborative signal sampling on 10 wireless mBCI devices. The average signal correlation reached 99.8%, the amplitude of average noise was 0.87 μV, and the average common mode rejection ratio (CMRR) reached 109.02 dB. The minimum synchronization error is 237 μs. We also tested the system in real-time processing of the steady-state visual-evoked potential (SSVEP) ranging from 8 to 15.8 Hz. Under 40 target stimulators, with 2 s data length, the average information transfer rate (ITR) reached 150 ± 20 bits/min, and the highest reached 260 bits/min, which was comparable to the marketing leading EEG system (the average: 150 ± 15 bits/min; the highest: 280 bits/min). The accuracy of target recognition in 2 s was 98%, similar to that of the Synamps2 (99%), but a higher signal-to-noise ratio (SNR) of 5.08 dB was achieved. We designed a group EEG cognitive experiment; to verify, this system can be used in noisy settings.

Significance

The evaluation results revealed that the proposed real-time group-synchronized neural recording system is a high-performance tool for real-time mBCI research. It is an enabler for a wide range of future applications in collaborative intelligence, cognitive neurology, and rehabilitation.

Optimization of ear electrodes for SSVEP-based BCI

OBJECTIVE

Current ear electrodes often require complex placing or long stimulation durations to achieve good detection of Steady-state visual evoked potential (SSVEP). To improve the practicability of ear electrode base SSVEP-BCI system, we developed a high-performance ear electrode that can be easily placed.

APPROACH

Hydrogel based disposable and replaceable semi-dry electrodes are developed to improve the contact impedance and wear feeling. The best combination of electrodes for SSVEP-BCI application around the ear is optimized by assessing the electrode on volunteers.

MAIN RESULTS

The developed ear hydrogel electrode can achieve an impedance close to that of the wet electrode. Three combinations of ear electrode groups demonstrate high information transfer rate (ITR) and accuracy in SSVEP-BCI applications. According to the rating of the comprehensive assessment and BCI performance in the online session, the behind-aural electrode is the best electrode combination for recording SSVEP in the ear region. The average preparation time is the shortest, and the average impedance is the lowest. The ITR of the behind-aural electrode based SSVEP-BCI system can reach 37.5±18 bits/min. The stimulus duration was as low as 3s compared to 5s or 10s in other studies.

SIGNIFICANCE

The accuracy, ITR, and wear feeling can be improved by introducing a semi-dry ear electrode and optimizing the position and the combination of ear electrode. The ear electrode base SSVEP-BCI promises to be used in daily life.&#xD.

A Self-Rectifying Synaptic Memristor Array with Ultrahigh Weight Potentiation Linearity for a Self-Organizing-Map Neural Network

Two-terminal self-rectifying (SR)-synaptic memristors are preeminent candidates for high-density and efficient neuromorphic computing, especially for future three-dimensional integrated systems, which can self-suppress the sneak path current in crossbar arrays. However, SR-synaptic memristors face the critical challenges of nonlinear weight potentiation and steep depression, hindering their application in conventional artificial neural networks (ANNs). Here, a SR-synaptic memristor (Pt/NiO_x/WO_3-x:Ti/W) and cross-point array with sneak path current suppression features and ultrahigh-weight potentiation linearity up to 0.9997 are introduced. The image contrast enhancement and background filtering are demonstrated on the basis of the device array. Moreover, an unsupervised self-organizing map (SOM) neural network is first developed for orientation recognition with high recognition accuracy (0.98) and training efficiency and high resilience toward both noises and steep synaptic depression. These results solve the challenges of SR memristors in the conventional ANN, extending the possibilities of large-scale oxide SR-synaptic arrays for high-density, efficient, and accurate neuromorphic computing.

[Lysosomal membrane protein Sidt2 knockout induces apoptosis of human hepatocytes in vitro independent of the autophagy-lysosomal pathway]

OBJECTIVE

To explore the regulatory mechanism of human hepatocyte apoptosis induced by lysosomal membrane protein Sidt2 knockout.

METHODS

The Sidt2 knockout (Sidt2^-/-) cell model was constructed in human hepatocyte HL7702 cells using Crispr-Cas9 technology.The protein levels of Sidt2 and key autophagy proteins LC3-II/I and P62 in the cell model were detected using Western blotting, and the formation of autophagosomes was observed with MDC staining.EdU incorporation assay and flow cytometry were performed to observe the effect of Sidt2 knockout on cell proliferation and apoptosis.The effect of chloroquine at the saturating concentration on autophagic flux, proliferation and apoptosis of Sidt2 knockout cells were observed.

RESULTS

Sidt2^-/- HL7702 cells were successfully constructed.Sidt2 knockout significantly inhibited the proliferation and increased apoptosis of the cells, causing also increased protein expressions of LC3-II/I and P62(P < 0.05) and increased number of autophagosomes.Autophagy of the cells reached a saturated state following treatment with 50 μmol/L chloroquine, and at this concentration, chloroquine significantly increased the expressions of LC3B and P62 in Sidt2^-/- HL7702 cells.

CONCLUSION

Sidt2 gene knockout causes dysregulation of the autophagy pathway and induces apoptosis of HL7702 cells, and the latter effect is not mediated by inhibiting the autophagy-lysosomal pathway.

[M2 macrophage-derived exosomal lncRNA NR_028113.1 promotes macrophage polarization possibly by activating the JAK2/STAT3 signaling pathway]

OBJECTIVE

To explore the effect of M2 macrophage-derived exosomal lncRNA NR_028113.1 on macrophage polarization and its possible mechanism.

METHODS

Bone marrow-derived macrophages (BMDMs) from BALB/c mice were isolated and cultured in vitro. After IL-4 treatment to induce M2 macrophage polarization, exosomes (M2-exo) were extracted from the supernatant of M2 macrophages and identified. The expression of lncRNA in M2-exo was detected by qRT-PCR. BMDMs were co-cultured with M2-exo (100 μg/mL) or PBS for 48 h, and the changes in cellular expression levels of Arg1, YM-1, FIZZ1, iNOS and TNF-α were detected using qRT-PCR and Western blotting. The percentage of CD206⁺ cells was analyzed using flow cytometry, and the phosphorylation levels of JAK2/STAT3 proteins were detected using Western blotting. A lncRNA smart silencer was designed to specifically inhibit the expression of lncRNA NR_028113.1 in the M2 macrophages, from which exosomes were extracted and co-cultured with BMDMs for 48 h. The mRNA expression levels of Arg1, YM-1, FIZZ1, iNOS and TNF-α, CD206⁺ cell percentage and the phosphorylation levels of JAK2/STAT3 proteins were detected using qRT-PCR, flow cytometry and Western blotting.

RESULTS

LncRNA NR_028113.1 was highly expressed in the exosomes of M2 macrophages (P < 0.05). Co-culture with M2-exo significantly increased mRNA expressions of M2 macrophage marker genes Arg1, YM-1 and FIZZ1 (P < 0.05), lowered the expressions of iNOS and TNF-α (P < 0.05), and increased CD206⁺ cell percentage and JAK2/STAT3 protein phosphorylation level in BMDMs (P < 0.05). After inhibiting the expression of lncRNA NR_028113.1 in M2 macrophages, the extracted M2-exo caused significant down-regulation of the mRNA expressions of Arg1, YM-1 and FIZZ1 and up-regulation of iNOS and TNF-α mRNA (P < 0.05), resulting also in signi-ficantly reduced CD206⁺ cell percentage and lowered phosphorylation levels of JAK2/STAT3 proteins in co-cultured BMDM (P < 0.05).

CONCLUSIONS

M2 macrophage-derived exosomal lncRNA NR_028113.1 can significantly promote M2 polarization of macrophages possibly by activating the JAK2/STAT3 signaling pathway.

A new grid stimulus with subtle flicker perception for user-friendly SSVEP-based BCIs

Objective.The traditional uniform flickering stimulation pattern shows strong steady-state visual evoked potential (SSVEP) responses and poor user experience with intense flicker perception. To achieve a balance between performance and comfort in SSVEP-based brain-computer interface (BCI) systems, this study proposed a new grid stimulation pattern with reduced stimulation area and low spatial contrast.Approach.A spatial contrast scanning experiment was conducted first to clarify the relationship between the SSVEP characteristics and the signs and values of spatial contrast. Four stimulation patterns were involved in the experiment: the ON and OFF grid stimulation patterns that separately activated the positive or negative contrast information processing pathways, the ON-OFF grid stimulation pattern that simultaneously activated both pathways, and the uniform flickering stimulation pattern that served as a control group. The contrast-intensity and contrast-user experience curves were obtained for each stimulation pattern. Accordingly, the optimized stimulation schemes with low spatial contrast (the ON-50% grid stimulus, the OFF-50% grid stimulus, and the Flicker-30% stimulus) were applied in a 12-target and a 40-target BCI speller and compared with the traditional uniform flickering stimulus (the Flicker-500% stimulus) in the evaluation of BCI performance and subjective experience.Main results.The OFF-50% grid stimulus showed comparable online performance (12-target, 2 s: 69.87 ± 0.74 vs. 69.76 ± 0.58 bits min^-1, 40-target, 4 s: 57.02 ± 2.53 vs. 60.79 ± 1.08 bits min^-1) and improved user experience (better comfortable level, weaker flicker perception and higher preference level) compared to the traditional Flicker-500% stimulus in both multi-targets BCI spellers.Significance.Selective activation of the negative contrast information processing pathway using the new OFF-50% grid stimulus evoked robust SSVEP responses. On this basis, high-performance and user-friendly SSVEP-based BCIs have been developed and implemented, which has important theoretical significance and application value in promoting the development of the visual BCI technology.

All-Optically Controlled Artificial Synapses Based on Light-Induced Adsorption and Desorption for Neuromorphic Vision

Artificial synapses with the capability of optical sensing and synaptic functions are fundamental components to construct neuromorphic visual systems. However, most reported artificial optical synapses require a combination of optical and electrical stimuli to achieve bidirectional synaptic conductance modulation, leading to an increase in the processing time and system complexity. Here, an all-optically controlled artificial synapse based on the graphene/titanium dioxide (TiO2) quantum dot heterostructure is reported, whose conductance could be reversibly tuned by the effects of light-induced oxygen adsorption and desorption. Synaptic behaviors, such as excitatory and inhibitory, short-term and long-term plasticity, and learning-forgetting processes, are implemented using the device. An artificial neural network simulator based on the artificial synapse was used to train and recognize handwritten digits with a recognition rate of 92.2%. Furthermore, a 5 × 5 optical synaptic array that could simultaneously sense and memorize light stimuli was fabricated, mimicking the sensing and memory functionality of the retina. Such an all-optically controlled artificial synapse shows a promising prospect in the application of perception, learning, and memory tasks for future neuromorphic visual systems.

A high-performance SSVEP-based BCI using imperceptible flickers

Objective.Existing steady-state visual evoked potential (SSVEP)-based brain-computer interfaces (BCIs) struggle to balance user experience and system performance. This study proposed an individualized space and phase modulation method to code imperceptible flickers at 60 Hz towards a user-friendly SSVEP-based BCI with high performance.Approach.The individualized customization of visual stimulation took the subject-to-subject variability in cortex geometry into account. An annulus global-stimulation was divided into local-stimulations of eight annular sectors and presented to subjects separately. The local-stimulation SSVEPs were superimposed to simulate global-stimulation SSVEPs with 4⁷space and phase coding combinations. A four-class phase-coded BCI diagram was used to evaluate the simulated classification performance. The performance ranking of all simulated global-stimulation SSVEPs were obtained and three performance levels (optimal, medium, worst) of individualized modulation groups were searched for each subject. The standard-modulation group conforming to the V1 'cruciform' geometry and the non-modulation group were involved as controls. A four-target phase-coded BCI system with SSVEPs at 60 Hz was implemented with the five modulation groups and questionnaires were used to evaluate user experience.Main results.The proposed individualized space and phase modulation method effectively modulated the SSVEP intensity without affecting the user experience. The online BCI system using the 60 Hz stimuli achieved mean information transfer rates of 52.8 ± 1.9 bits min^-1, 16.8 ± 2.4 bits min^-1, and 42.4 ± 3.0 bits min^-1with individualized optimal-modulation, individualized worst-modulation, and non-modulation groups, respectively.Significance.Structural and functional characteristics of the human visual cortex were exploited to enhance the response intensity of SSVEPs at 60 Hz, resulting in a high-performance BCI system with good user experience. This study has important theoretical significance and application value for promoting the development of the visual BCI technology.

Hypothalamic warm-sensitive neurons require TRPC4 channel for detecting internal warmth and regulating body temperature in mice

Precise monitoring of internal temperature is vital for thermal homeostasis in mammals. For decades, warm-sensitive neurons (WSNs) within the preoptic area (POA) were thought to sense internal warmth, using this information as feedback to regulate body temperature (T_core). However, the cellular and molecular mechanisms by which WSNs measure temperature remain largely undefined. Via a pilot genetic screen, we found that silencing the TRPC4 channel in mice substantially attenuated hypothermia induced by light-mediated heating of the POA. Loss-of-function studies of TRPC4 confirmed its role in warm sensing in GABAergic WSNs, causing additional defects in basal temperature setting, warm defense, and fever responses. Furthermore, TRPC4 antagonists and agonists bidirectionally regulated T_core. Thus, our data indicate that TRPC4 is essential for sensing internal warmth and that TRPC4-expressing GABAergic WSNs function as a novel cellular sensor for preventing T_core from exceeding set-point temperatures. TRPC4 may represent a potential therapeutic target for managing T_core.

Implantable intracortical microelectrodes: reviewing the present with a focus on the future

Implantable intracortical microelectrodes can record a neuron's rapidly changing action potentials (spikes). In vivo neural activity recording methods often have either high temporal or spatial resolution, but not both. There is an increasing need to record more neurons over a longer duration in vivo. However, there remain many challenges to overcome before achieving long-term, stable, high-quality recordings and realizing comprehensive, accurate brain activity analysis. Based on the vision of an idealized implantable microelectrode device, the performance requirements for microelectrodes are divided into four aspects, including recording quality, recording stability, recording throughput, and multifunctionality, which are presented in order of importance. The challenges and current possible solutions for implantable microelectrodes are given from the perspective of each aspect. The current developments in microelectrode technology are analyzed and summarized.

[A fixed cohort study of disability trajectory of the dying elderly in China]

Objective: To explore the trajectory of disability in the dying elderly in China. Methods: Based on the activity of daily living (ADL) data from the 2002-2018 Chinese Longitudinal Healthy Longevity Survey, the longitudinal item response theory (LIRT) model was fitted with the difficulty threshold parameters to analyze the ADL loss in the elderly in China. Then, a mixed-effects model was fitted to analyze the trajectory of the disability level of the dying elderly. Results: A total of 5 817 old adults who entered the cohort in 2002 were included, in whom 41.81% were males, with a baseline age of (86.80±12.40) years and a follow-up time of 4 (3,8) years. The results of LIRT showed that the lowest difficulty threshold parameter in the basic activity of daily living (BADL) was partially disability on bathing (0.41±0.05), and the highest was entirely disability on indoor movement (6.19±0.16). In comparison, the lowest difficulty threshold parameter in instrumental activity of daily living (IADL) was partially disability on using public transportation (-3.01±0.07), and the highest was entirely disability on visiting neighbors (1.51±0.07). In the trajectory of disability, the average dependency in ADL was lower in dying men than in dying women (P<0.001), in the elderly living alone than in the elderly living with family members (P<0.001) and in the non-illiterate elderly than in the illiterate elderly (P<0.001). The estimated value of both the linear change rate and quadratic coefficient of disability level development with time were 0.231 (P<0.001) and 0.002 (P<0.001). Conclusions: In China, the development of disability in the elderly in China has its characteristics, IADL disability might occurs earlier than BADL. Among the IADL/BADL items, the disability of lower limb-based items is more prone to occur compared with upper limb-based items, and the disability of complex items is more prone to occur compared with simple items, and the growth rate of the disability trajectory also accelerates over time. It is necessary to pay attention to old women, old people living with family members, old people with low education level and old people with poor cognitive function in the disability prevention.

Minimally Invasive Local-Skull Electrophysiological Modification With Piezoelectric Drill

The research on non-invasive BCI is nowadays hitting the bottleneck due to the humble quality of scalp EEG signals. Whereas invasive solutions that offer higher signal quality in contrast are suffocated in their spreading because of the potential surgical complication and health risks caused by electrode implantation. Therefore, it puts forward a necessity to explore a scheme that could both collect high-quality EEG signals and guarantee high-level operation safety.This study proposed a Minimally Invasive Local-skull Electrophysiological Modification method to improve scalp EEG signals qualities at specific brain regions. Six eight-month-old SD rats were used for in vivo verification experiment. A hole with a diameter of about 500 micrometers was drilled in the skull above the visual cortex of rats. Significant changes in rsEEG and SSVEP signals before and after modification were observed. After modification, the skull impedance of rats decreases by about 84 %, the average maximum bandwidth of rsEEG increase by 57 %, and the broadband SNR of SSVEP is increased by 5.13 dB. The time of piezoelectric drilling operation is strictly controlled under 30 seconds for each rat to prevent possible brain damage from overheating. Compared with traditional invasive procedures such as ECoG, Minimally Invasive Local-skull Electrophysiological Modification operation time is shorter and no electrode implantation is needed while it remarkably boosts the scalp EEG signal quality. This technical solution has the potential to replace the use of ECoG in certain application scenarios and further invigorate studies in the field of scalp EEG in the future.

Non-Invasive Stable Sensory Feedback for Closed-Loop Control of Hand Prosthesis

The absence of somatotopic sensory feedback limits the function of conventional prosthetic hands. In this study, we integrated a non-invasive sensory feedback system into a commercial Bebionic hand with new customized surface stimulation electrodes. Multiple modalities of tactile and hand aperture sensory information were conveyed to the amputee via the technique of evoked tactile sensation (ETS) elicited at projected finger map (PFM) of residual limb and an additional electrotactile stimulation in the ipsilateral upper arm. A previously developed anti-stimulus artifact module was used to remove the stimulus artifact from surface electromyographic (sEMG) signals, and the filtered sEMG envelops controlled the speed of open/close of the Bebionic hand. The Ag/AgCl surface stimulation electrode in 10-mm diameter was specially designed to fit the restricted PFM areas for stable perception. We evaluated the alternating-current (AC) impedance magnitude of this electrode stimulated over 12 hours. The perceptual and upper thresholds in pulse-width over 200 days at PFM areas were recorded to assess the stability of the non-invasive sensory neural interface. The efficacy of multi-modality feedback for identification of physical properties of objects was also assessed. Results showed that the AC impedance of customized surface stimulation electrode was stable over 12 hours of stimulation. The perceptual and upper thresholds were stable over 200 days. This non-invasive sensory feedback enabled a forearm amputee to identify the compliance and length of grasped objects with an accuracy of 100 %. Results illustrated that the multi-modality sensory feedback system provided stable and sufficient sensory information for perceptual discrimination of physical features of grasped objects. Clinical Relevance- This study demonstrated a promising and novel way to restore stable sensory feedback non-invasively for commercial hand prostheses.

Distributed implantation of a flexible microelectrode array for neural recording

Flexible multichannel electrode arrays (fMEAs) with multiple filaments can be flexibly implanted in various patterns. It is necessary to develop a method for implanting the fMEA in different locations and at various depths based on the recording demands. This study proposed a strategy for reducing the microelectrode volume with integrated packaging. An implantation system was developed specifically for semiautomatic distributed implantation. The feasibility and convenience of the fMEA and implantation platform were verified in rodents. The acute and chronic recording results provied the effectiveness of the packaging and implantation methods. These methods could provide a novel strategy for developing fMEAs with more filaments and recording sites to measure functional interactions across multiple brain regions.

Flexible terahertz metamaterial biosensor for label-free sensing of serum tumor marker modified on a non-metal area

Terahertz (THz) metamaterials for rapid label-free sensing show application potential for the detection of cancer biomarkers. A novel flexible THz metamaterial biosensor based on a low refraction index parylene-C substrate is proposed. The biomarkers are modified on non-metal areas by a three-step modification method that simplifies the modification steps and improves the modified effectivity. Simulation results for non-metal modification illustrate that a bulk refractive index sensitivity of 325 GHz/RIU is achieved, which is larger than that obtained for the traditional metal modification (147 GHz/RIU). Meanwhile, several fluorescence experiments proved the uniform modification effect and selective adsorption capacity of the non-metal modification method. The concentration of the carcinoembryonic antigen (CEA) biomarkers for breast cancer patients tested using this THz biosensor is found to be consistent with results obtained from traditional clinical tests. The limit of detection reaches 2.97 ng/mL. These findings demonstrate that the flexible THz metamaterial biosensor can be extensively used for the rapid detection of cancer biomarkers in the future.

A Pre-gelled EEG Electrode and Its Application in SSVEP-based BCI

Electroencephalogram (EEG) electrodes are critical devices for brain-computer interface and neurofeedback. A pre-gelled (PreG) electrode was developed in this paper for EEG signal acquisition with a short installation time and good comfort. A hydrogel probe was placed in advance on the Ag/AgCl electrode before wearing the EEG headband instead of a time-consuming gel injection after wearing the headband. The impedance characteristics were compared between the PreG electrode and the wet electrode. The PreG electrode and the wet electrode performed the Brain-Computer Interface (BCI) application experiment to evaluate their performance. The average impedance of the PreG electrode can be decreased to 43 kΩ or even lower, which is higher than the wet electrode with an impedance of 8 kΩ. However, there is no significant difference in classification accuracy and information transmission rate (ITR) between the PreG electrode and the wet electrode in a 40 target BCI system based on Steady State Visually Evoked Potential (SSVEP). This study validated the efficiency of the proposed PreG electrode in the SSVEP-based BCI. The proposed PreG electrode will be an excellent substitute for wet electrodes in an actual application with convenience and good comfort.

Wireless Closed-Loop Optical Regulation System for Seizure Detection and Suppression In Vivo

There are approximately 50 million people with epilepsy worldwide, even about 25% of whom cannot be effectively controlled by drugs or surgical treatment. A wireless closed-loop system for epilepsy detection and suppression is proposed in this study. The system is composed of an implantable optrode, wireless recording, wireless energy supply, and a control module. The system can monitor brain electrical activity in real time. When seizures are recognized, the optrode will be turned on. The preset photosensitive caged compounds are activated to inhibit the seizure. When seizures are inhibited or end, the optrode is turned off. The method demonstrates a practical wireless closed-loop epilepsy therapy system.

A Hybrid Brain-Computer Interface Based on Visual Evoked Potential and Pupillary Response

Brain-computer interface (BCI) based on steady-state visual evoked potential (SSVEP) has been widely studied due to the high information transfer rate (ITR), little user training, and wide subject applicability. However, there are also disadvantages such as visual discomfort and “BCI illiteracy.” To address these problems, this study proposes to use low-frequency stimulations (12 classes, 0.8–2.12 Hz with an interval of 0.12 Hz), which can simultaneously elicit visual evoked potential (VEP) and pupillary response (PR) to construct a hybrid BCI (h-BCI) system. Classification accuracy was calculated using supervised and unsupervised methods, respectively, and the hybrid accuracy was obtained using a decision fusion method to combine the information of VEP and PR. Online experimental results from 10 subjects showed that the averaged accuracy was 94.90 ± 2.34% (data length 1.5 s) for the supervised method and 91.88 ± 3.68% (data length 4 s) for the unsupervised method, which correspond to the ITR of 64.35 ± 3.07 bits/min (bpm) and 33.19 ± 2.38 bpm, respectively. Notably, the hybrid method achieved higher accuracy and ITR than that of VEP and PR for most subjects, especially for the short data length. Together with the subjects’ feedback on user experience, these results indicate that the proposed h-BCI with the low-frequency stimulation paradigm is more comfortable and favorable than the traditional SSVEP-BCI paradigm using the alpha frequency range.

[Application and prospect of cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy in the treatment of peritoneal metastasis from colorectal cancer]

Colorectal cancer is one of the common malignant tumors in China, and its incidence is increasing with years. As the second most common metastatic site of colorectal cancer, peritoneum is difficult to diagnose early and with a poor prognosis. Systemic intravenous chemotherapy was used as the main treatment strategy for peritoneal metastasis in the past, but its systemic toxic and side effects were obvious, and it could not effectively control tumor progression. In recent years, the continuous development of surgical techniques, concepts, and equipment, as well as the introduction of new chemotherapy drugs and targeted drugs have significantly improved the quality of life and prognosis of patients with peritoneal metastasis of colorectal cancer. Cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) can effectively eradicated the intraperitoneal free cancer cells and subclinical lesions, while reducing systemic side effects of chemotherapy drugs, and achieve the radical cure of the tumor at the macro and micro levels to the greatest extent. It has been used as the first-line treatment program for peritoneal metastasis of colorectal cancer at home and abroad. This article focuses on the analysis and summary of the survival efficacy, prognostic factor analysis, and chemotherapy safety of CRS+ HIPEC in the treatment of colorectal cancer peritoneal metastasis. The existing problems and controversies of HIPEC therapy are discussed simultaneously.

A high-performance brain switch based on code-modulated visual evoked potentials

OBJECTIVE

Asynchronous brain-computer interfaces (BCIs) are more practical and natural compared to synchronous BCIs. A brain switch is a standard asynchronous BCI, which can automatically detect the specified change of the brain and discriminate between the control state and the idle state. The current brain switches still face challenges on relatively long reaction time (RT) and high false positive rate (FPR).

APPROACH

In this paper, an online electroencephalography-based brain switch is designed to realize a fast reaction and keep long idle time (IDLE) without false positives (FPs) using code-modulated visual evoked potentials (c-VEPs). Two stimulation paradigms were designed and compared in the experiments: multi-code concatenate modulation (concatenation mode) and single-code periodic modulation (periodic mode). Using a task-related component analysis-based detection algorithm, EEG data can be decoded into a series of code indices. Brain states can be detected by a template matching approach with a sliding window on the output series.

MAIN RESULTS

The online experiments achieved an average RT of 1.49 seconds when the average IDLE for each FP was 68.57 minutes (1.46e-2 FP/min) or an average RT of 1.67 seconds without FPs.

SIGNIFICANCE

This study provides a practical c-VEP based brain switch system with both fast reaction and low FPR during idle state, which can be used in various BCI applications.

Analysis of Electromagnetic Interference and Shielding in the μLED Optrode Based on Finite Element Method

Monolithic integrated μLED optrode has promising applications in optogenetics due to their ability to achieve more optical channels in a smaller footprint. The current used to drive the μLED will cause electromagnetic interference (EMI) noise to the recording electrodes at a very close distance. Utilizing a grounded metal shielding layer between the active device and the electrode can potentially reduce the interference. In this paper, multi-dimensional μLED optrode models are set up according to the real device. By numerically analyzing the electromagnetic interference between the μLED and recording electrodes, several optimized shielding schemes are evaluated by simulations and experiments. Some important process and layout parameters that may influence the shielding effect are studied through the finite element method (FEM). Different circuit models based on the corresponding test environment are built to analyze the simulation and experiment results. A new PCB with a shielding layer has been designed and initially verified. The proposed novel computational model can analyze EMI quantitatively, which could facilitate the design of low-noise μLED optrode with reasonable shielding and packaging.

Optimizing spatial properties of a new checkerboard-like visual stimulus for user-friendly SSVEP-based BCIs

Objective.Low-frequency steady-state visual evoked potential (SSVEP)-based brain-computer interface (BCI) systems with high performance are prone to cause visual discomfort and fatigue. High-frequency SSVEP-based BCI systems can alleviate the discomfort, but always obtain lower performance. This study optimized the spatial properties of a proposed checkerboard-like visual stimulus toward high-performance and user-friendly SSVEP-based BCI systems.Approach.On the one hand, two checkerboard-like stimuli with distinct spatial contrasts (the black- and white-background) were designed to balance the tradeoff between BCI performance and user experience and compared with the traditional flickering stimulus. On the other hand, the impacts of the spatial frequency of the new checkerboard-like stimulus on the flicker perception and the intensity of the elicited SSVEP were clarified. The SSVEP-based BCI systems were implemented based on the checkerboard-like stimuli under low-frequency and high-frequency conditions. The user experience for each stimulation pattern was estimated by questionnaires for subjective evaluation.Main results.The comparison results indicate that the black-background checkerboard-like stimulus with an optimized spatial frequency achieved comparable performance and enhanced visual comfort compared with the flickering stimulus. Furthermore, the online nine-target BCI system using the black-background checkerboard-like stimuli achieved averaged information transfer rates of 124.0 ± 2.3 and 109.0 ± 20.4 bits min^-1with low-frequency and high-frequency stimulation respectively.Significance.The new checkerboard-like stimuli with optimized properties show superiority of system performance and user experience in implementing SSVEP-based BCI, which will promote its practical applications in communication and control.

A Modified Miniscope System for Simultaneous Electrophysiology and Calcium Imaging in vivo

The miniscope system is one of the calcium (Ca²⁺) imaging tools with small size and lightweight and can realize the deep-brain Ca²⁺ imaging not confined to the cerebral cortex. Combining Ca²⁺ imaging and electrophysiology recording has been an efficient method for extracting high temporal-spatial resolution signals in the brain. In this study, a particular electrode probe was developed and assembled on the imaging lens to modify the miniscope system. The electrode probe can be tightly integrated into the lens of the miniscope without increasing the volume, weight, and implantation complexity. In vivo tests verified that the proposed modified system has realized the simultaneous recording of Ca²⁺ signals and local field potential (LFP) signal in the hippocampus CA1 region of an adult mouse.

Rewritable PEDOT Film Based on Water-Writing and Electroerasing

Rewritable paper has greatly promoted the sustainable development of society. However, the hydrophilicity/lipophilicity of the poly(3,4-ethylenedioxythiophene) (PEDOT) film limits its application as the rewritable paper. Herein, we constructed a repeatable writing/erasing pattern on a PEDOT film (rewritable PEDOT paper) by combining wettability control, water-induced dedoping, and an electrochemical redox reaction. The treatment with a medium-polarity/high-volatility solvent (MP/HVS) adjusted the wettability of the PEDOT film (water contact angle increased from 6.5° to 146.2°), contributing to the formation of a hydrophobic writable substrate. The treatment with a high-polarity solvent (HPS) induced the dedoping of anions in the PEDOT chain, resulting in the film's color changed from blue to purple and serving as a writing process. The intrinsic electrochemical redox (elimination of color change by doping/dedoping of lithium ions in the PEDOT chain) of the PEDOT film enabled the erasing process. This writing/erasing process can be repeated at least 10 times. The patterned PEDOT film maintained excellent stability to standing diverse solvents (low-polarity solvent (LPS) and MP/HVS), high temperatures (350 °C), and irradiation of different light wavelengths (wavelengths of 365, 380, 460, 520, and 645 nm). Additionally, the conductivity of the PEDOT film was quantitatively measured (impedance: LPS, increased 8.84%; MP/HVS, decreased 6.67%; and HPS, increased 27.97%) by fabricating a micropatterned PEDOT electrode. This work will provide a method for the fabrication of PEDOT-based optoelectronic functional materials.

Research on Pt/NiOx/WO3-x:Ti/W Multijunction Memristors with Synaptic Learning and Memory Functions

Artificial synapses based on biological synapses represent a new idea in the field of artificial intelligence with future applications. Current two-terminal RRAM devices have developed tremendously due to the adjustable synaptic plasticity of artificial synapses. However, these devices still have some problems, such as current leakage and poor durability. Here, we demonstrate a Pt/NiO_x/WO_3-x:Ti/W memristor with a pn-type heterojunction and two metal-semiconductor contacts, which exhibits good rectification. Due to the change in the internal potential barrier, the devices possess multiconductance states under different pulse modulations and memory characteristics, similar to synapses. The rectification characteristics of the device exhibit stable enhancement and suppression behavior. Each device in the 10 × 10 cross array we constructed can be written correctly, which verifies that leakage current does not appear in the device. The structure proposed in this work has great significance for the integration of large-scale memristor cross arrays.

Route to Cost-Effective Fabrication of Wafer-Scale Nanostructure through Self-Priming Nanoimprint

Nanoimprint technology is powerful for fabricating nanostructures in a large area. However, expensive equipment, high cost, and complex process conditions hinder the application of nano-imprinting technology. Therefore, double-layer self-priming nanoimprint technology was proposed to fabricate ordered metal nanostructures uniformly on 4-inch soft and hard substrates without the aid of expensive instruments. Different nanostructure (gratings, nanoholes and nanoparticles) and different materials (metal and MoS2) were patterned, which shows wide application of double-layer self-priming nanoimprint technology. Moreover, by a double-layer system, the width and the height of metal can be adjusted through the photoresist thickness and developing condition, which provide a programmable way to fabricate different nanostructures using a single mold. The double-layer self-priming nanoimprint method can be applied in poor condition without equipment and be programmable in nanostructure parameters using a single mold, which reduces the cost of instruments and molds.

Wearable Contact Lens Sensor for Non-invasive Continuous Monitoring of Intraocular Pressure

Intraocular pressure (IOP) is an essential indicator of the diagnosis and treatment of glaucoma. IOP has an apparent physiological rhythm, and it often reaches its peak value at night. To avoid missing the peak value at night and sample the entire rhythm cycle, the continuous monitoring of IOP is urgently needed. A wearable contact lens IOP sensor based on a platinum (Pt) strain gauge is fabricated by the micro-electro-mechanical (MEMS) process. The structure and parameters of the strain gauge are optimized to improve the sensitivity and temperature stability. Tests on an eyeball model indicate that the IOP sensor has a high sensitivity of 289.5 μV/mmHg and excellent dynamic cycling performance at different speeds of IOP variation. The temperature drift coefficient of the sensor is 33.4 μV/°C. The non-invasive IOP sensor proposed in this report exhibits high sensitivity and satisfactory stability, promising a potential in continuous IOP monitoring.

A Cross-Session Dataset for Collaborative Brain-Computer Interfaces Based on Rapid Serial Visual Presentation

Brain-computer interfaces (BCIs) based on rapid serial visual presentation (RSVP) have been widely used to categorize target and non-target images. However, it is still a challenge to detect single-trial event related potentials (ERPs) from electroencephalography (EEG) signals. Besides, the variability of EEG signal over time may cause difficulties of calibration in long-term system use. Recently, collaborative BCIs have been proposed to improve the overall BCI performance by fusing brain activities acquired from multiple subjects. For both individual and collaborative BCIs, feature extraction and classification algorithms that can be transferred across sessions can significantly facilitate system calibration. Although open datasets are highly efficient for developing algorithms, currently there is still a lack of datasets for a collaborative RSVP-based BCI. This paper presents a cross-session EEG dataset of a collaborative RSVP-based BCI system from 14 subjects, who were divided into seven groups. In collaborative BCI experiments, two subjects did the same target image detection tasks synchronously. All subjects participated in the same experiment twice with an average interval of ∼23 days. The results in data evaluation indicate that adequate signal processing algorithms can greatly enhance the cross-session BCI performance in both individual and collaborative conditions. Besides, compared with individual BCIs, the collaborative methods that fuse information from multiple subjects obtain significantly improved BCI performance. This dataset can be used for developing more efficient algorithms to enhance performance and practicality of a collaborative RSVP-based BCI system.

First Report of Root Rot Caused by Dactylonectria torresensis on Bletilla striata (Baiji) in Yunnan, China

Bletilla striata (Thunb.) Rchb.f. (Orchidaceae family, known as Baiji in Chinese) is an endangered plant species with important medicinal value in China. Bletilla striata plants with symptoms of wilting, leaf yellowing and rotting on underground parts were found in Shizong (24.82822 N; 103.99084 E), Yunnan Province, China in July 2016. In the following years, this disease occurred and became prevalent when high temperature and high humidity prevailed in the fields from May to August. The incidence of the disease varied from 45 to 75%, with yield losses of 40 to 65% in different B. striata fields. To identify the causal agent of the disease, symptomatic vascular tissue fragments were soaked in 2% sodium hypochlorite for 2 min, rinsed twice with sterile distilled water, and then placed on 4% (w/v) potato dextrose agar (PDA) plates. The plates were incubated at 26°C in 12h light/dark for three days. Mycelia grown from the edges of the plant fragments were transferred to PDA plates and incubated at 26°C in 12h light/dark. After three days, hyphal tips were isolated from the edge of the colonies to PDA plates. Three hyphal-tip isolates from different plants were further studied. The colonies of these three isolates were dark red, with cottony mycelia of moderate density. Hyphae were transparent and branched. Numerous hyphae anastomosed frequently and formed hyphal coils. For further morphological analysis, sporulation was induced as described by Cabral et al. (2012) and Lombard et al. (2014). Macroconidia were abundant, 37.2 to 44.0 µm × 5.2 to 8.7 µm based on the measurement of 20 conidia from each isolate. Ascospores divided into two cells of equal size, ellipsoid to oblong-ellipsoid, 12.5 to 14.8 µm × 4.8 to 5.9 µm based on the measurement of 20 spores from each isolate. Conidiophores simple or complex, sporodochial. Simple conidiophores arising laterally or terminally from aerial mycelium, solitary to loosely aggregated, unbranched or sparsely brached, more or less cylindrical. These morphological characteristics were consistent with the description of Dactylonectria spp. by Cabral et al. (2012) and Lombard et al. (2014). From one isolate, the internal transcribed spacer (ITS) region of ribosomal DNA and the beta-tubulin (tub2) gene were amplified by polymerase chain reaction (PCR) using the primer pairs ITS1/ITS4 (White et al. 1990) and T1/Bt-2b (Cabral et al. 2012), respectively. PCR products were sequenced and deposited in GenBank with accession numbers MH458779 (ITS) and MH626485 (tub2). BLAST search revealed that both sequences showed 99 to 100% homology with the corresponding sequences of previously identified D. torresensis isolates. Specially, MH458779 shares 100% identity with the entire 463-base pair (bp) sequence of KP411806, the ITS sequence of a D. torresensis isolate identified from olive trees (Nigro et al. 2019); MH626485 shares 99% identity with the entire 320-bp sequence of KP411801, the tub2 sequence of the same olive tree isolate. In addition, the entire 609-bp sequence of MH626485 shares 99% identity with JF735478, the tub2 sequence of a D. torresensis isolate identified from grapevines (Cabral et al. 2012). To test the pathogenicity of the fungus, plants of B. striata in plastic pots filled with sterilized nursery soil were inoculated with each of the three isolates by placing a fungal-colonized wheat kernel adjacent to each health plant. Plants inoculated with noncolonized wheat kernels were used as controls. Plants in three pots (replicates), with one plant per pot, were inoculated by each isolate. The pots were maintained in a greenhouse with a 12h photoperiod at 25°C. Ten days after inoculation, black necrotic lesions identical to those observed in the field were evident on the roots of all inoculated plants. Using the same methods described above, fungi with identical morphologies as described above were isolated from lesions caused by each of the three isolates. The control plants remained healthy, and no fungus was re-isolated. This completed Koch's postulates. Based on the morphological characteristics and molecular identification, the pathogen was determined to be D. torresensis. To our knowledge, this is the first report of D. torresensis causing root rot of B. striata in Yunnan, China. It is important to further study the impacts of this new disease on B. striata production in China.

[Analysis of risk factors of severe postoperative complications in elderly patients with colorectal cancer aged over 80 years]

Objective: To investigate the risk factors of severe postoperative complications in elderly patients with colorectal cancer aged over 80 years old. Methods: A retrospective case-control study was conducted to collect and analyze the clinicopathological data of patients (≥80 years old) who underwent radical colorectal cancer surgery at department of Colorectal Surgery, Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College from January 2010 to December 2018. A total of 269 patients were included in the study, including 160 males and 109 females. The average age was 83 (80-94) years. Among them, the pathological TNM stage was 16 in stage I, 76 in stage II, 167 in stage III, and 10 in stage IV. According to Clavien-Dindo classification, the postoperative complications of grade III and above were defined as serious complications. To analyze the relationship between the patient's clinical data, such as general information, the surgeon's experience (whether to complete more than 500 radical colorectal cancer surgery), intraoperative conditions and the occurrence of severe complications. Univariate analysis was conducted with the chi-squared test. Multivariate logistic regression analysis was used for statistically significant variables in univariate analysis. Results: Of the 269 patients, 34 (12.6%) had severe complications after surgery. The incidence of postoperative complications ranged from high to low, respectively, for pulmonary infection (8/269,3.0%), intestinal obstruction (8/269, 3.0%) and anastomotic leakage (7/269, 2.6%). One patient died of pulmonary embolism and one patient died of multiple organ failure, with a perioperative mortality rate of 0.7% (2/269). On univariate analysis, the occurrence of severe postoperative complications was associated with age (χ(2)=8.181, P=0.004), American society of anesthesiologists grade (χ(2)=7.945, P=0.005), preoperative albumin level (χ(2)=9.088, P=0.003), operation experience (χ(2)=9.395, P=0.002). Multivariable logistic regression analysis showed that age ≥85 years old (OR=4.415, 95% CI: 1.702-11.453, P=0.080), preoperative albumin <35 g/L (OR=2.544, 95%CI: 1.083-5.974, P=0.032), and less-experieced group (OR=2.475, 95% CI:1.082-5.661, P=0.032) was independent risk factor for severe postoperative complications. The incidence of serious postoperative complications was similar in patients undergoing laparoscopy and laparotomy [10.1% (17/169) vs. 17.0% (17/100), χ(2)=2.741, P=0.098]. Conclusion: Adequate preoperative evaluation, appropriate perioperative nutritional support and experienced specialists are the key factors to ensure the successful perioperative period of elderly patients with colorectal cancer aged over 80 years old. In addition, more attention should be paid to the elderly patients aged ≥85 years.

Characteristics of High-Frequency SSVEPs Evoked by Visual Stimuli at Different Polar Angles

The mapping of visual space onto human striate cortex allows the location of stimuli to affect the scalp distributions of electroencephalogram (EEG). To clarify the relationship between the characteristics of elicited high-frequency steady-state visual evoked potentials (SSVEPs) and the polar angle of stimulus, this study divided the annulus into eight symmetrical annular sectors (i.e., octants) as separate visual stimuli. For both 30 Hz and 60 Hz, the response intensity and classification accuracy indicated that the annular sectors in the lower visual field evoked stronger responses than those in the upper visual field. This paper also evaluated the phase differences between SSVEPs at specific polar angles and found clear individual differences across subjects. These findings may lead to inspirations for the design of new space coding methods for the SSVEP-based brain-computer interfaces (BCIs).

Comparison of Pupil Size and Visual Evoked Potentials under 1-6Hz Visual Stimulation

In order to explore the effect of low frequency stimulation on pupil size and electroencephalogram (EEG), we presented subjects with 1-6Hz black-and-white-alternating flickering stimulus, and compared the differences of signal-to-noise ratio (SNR) and classification performance between pupil size and visual evoked potentials (VEPs). The results showed that the SNR of the pupillary response reached the highest at 1Hz (17.19± 0.10dB) and 100% accuracy was obtained at 1s data length, while the performance was poor at the stimulation frequency above 3Hz. In contrast, the SNR of VEPs reached the highest at 6Hz (18.57± 0.37dB), and the accuracy of all stimulus frequencies could reach 100%, with the minimum data length of 1.5s. This study lays a theoretical foundation for further implementation of a hybrid brain-computer interface (BCI) that integrates pupillometry and EEG.

A Four-Class Phase-Coded SSVEP BCI at 60Hz Using Refresh Rate

A four-class brain-computer interface (BCI) system based on steady-state visual evoked potentials (SSVEPs) was developed by presenting phase-coded 60Hz stimulations on a 240Hz LCD monitor. The task-related component analysis (TRCA) algorithm was used to detect SSVEPs with individual training data. In the BCI experiment with 10 subjects, the system achieved high classification accuracy of 94.50±6.70% and 92.71±7.56% in offline and online BCI experiments, resulting in information transfer rates (ITR) of 19.95±4.36 and 18.81±4.74 bpm, respectively. The behavioral tests on visual comfortableness and perception of flickering reveal that the proposed BCI system is very comfortable to use without any perception of flicker.

A Fast Brain Switch Based on Multi-Class Code-Modulated VEPs

To realize asynchronous control of a brain-computer interface (BCI) system, a fast brain switch with low false positive rate (FPR) is required. This paper proposed a brain switch based on code-modulated visual-evoked potential (c-VEP), in which seven 8-bit pseudorandom codes were used to modulate the electroencephalogram (EEG) signal. This study optimized and demonstrated the control strategy through an offline and an online experiments. By decoding the brain state continuously with the task-related component analysis (TRCA) algorithm, the brain switch achieved an average reaction time (RT) of 1.72 seconds and an average idle time of 183.53 seconds without false positive events in the online experiment.

Application of graphene nanowalls in an intraocular pressure sensor

Combining crack mechanism in GNWs with the stretchability of PDMS, a contact lens sensor exhibits excellent sensitivity to intraocular pressure.

Physical mechanism for the synapse behaviour of WTiOx-based memristors

Tungsten-based memristors possess many advantages as candidates for memristive devices, including gradual changes in resistance states and memorization and learning functions. However, most previous reports mainly focus on studying synaptic learning rules instead of analysing the internal mechanism that results in the exterior learning rules. Herein, we discuss stacked Au/WTiO_x/Au and Ti/WTiO_x/Au devices in which the function of the resistance switch is realized by the externally induced local migration of oxygen ions. The consecutively adjustable multilevel resistance of the Au/WTiO_x/Au device may be due to the variation in the barrier width and height in high oxygen vacancy concentrations. Additionally, the high and low resistance states of Ti/WTiO_x/Au devices are considered as a result of the connection and rupture of the conductive filaments at low concentrations of oxygen vacancies. The physical mechanism construction and state-full synapse development through the control of ion migration provide insight into the applications of oxide-based memristors in neuromorphic computation.

Exploring surface sensitivity of Rayleigh anomaly in metal/dielectric multilayer gratings

Biosensors based on Rayleigh anomaly (RA) in metal gratings exhibit impressive bulk refractive index (RI) sensitivity and narrow linewidth. However, the electric field enhancement extends far away from surface of the gratings, which limits the application on biosensor where the RI changes are restricted at the sensor interface. To overcome this shortcoming, a novel grating composed of a 8-layer Au/Al₂O₃ stack was optimized by numerical simulation. The electric field is limited in several hundreds of nanometers from surface. The surface sensitivity increases 10 times than that of Au gratings at the detection depth of less than 400 nm. The surface index sensitivity can be improved 5 times under oblique incidence than that under normal incidence when the thickness of cover media is 20 nm.

Novel small molecule IL-6 inhibitor suppresses autoreactive Th17 development and promotes Treg development

Multiple sclerosis (MS) is the leading cause of non-traumatic neurological disability in the United States in young adults, but current treatments are only partially effective, making it necessary to develop new, innovative therapeutic strategies. Myelin-specific interleukin (IL)-17-producing T helper type 17 (Th17) cells are a major subset of CD4 T effector cells (T_eff ) that play a critical role in mediating the development and progression of MS and its mouse model, experimental autoimmune encephalomyelitis (EAE), while regulatory T cells (T_reg ) CD4 T cells are beneficial for suppressing disease. The IL-6/signal transducer and activator of transcription 3 (STAT-3) signaling pathway is a key regulator of Th17 and T_reg cells by promoting Th17 development and suppressing T_reg development. Here we show that three novel small molecule IL-6 inhibitors, madindoline-5 (MDL-5), MDL-16 and MDL-101, significantly suppress IL-17 production in myelin-specific CD4 T cells in a dose-dependent manner in vitro. MDL-101 showed superior potency in suppressing IL-17 production compared to MDL-5 and MDL-16. Treatment of myelin-specific CD4 T cells with MDL-101 in vitro reduced their encephalitogenic potential following their subsequent adoptive transfer. Furthermore, MDL-101 significantly suppressed proliferation and IL-17 production of anti-CD3-activated effector/memory CD45RO⁺ CD4⁺ human CD4 T cells and promoted human T_reg development. Together, these data demonstrate that these novel small molecule IL-6 inhibitors have the potential to shift the T_eff  : T_reg balance, which may provide a novel therapeutic strategy for ameliorating disease progression in MS.