Evaluating the impact of transcranial electrical stimulation on post-stroke dysphagia: a systematic review and meta-analysis.

OBJECTIVE: To conduct a systematic review and meta-analysis to assess the impact of transcranial electrical stimulation (TES), proposed as a potential therapy for post-stroke dysphagia, on swallowing function in stroke survivors. METHODS: The PubMed, Embase, Web of Science, and Cochrane Library databases were searched for relevant studies on TES for post-stroke dysphagia. Search results were reviewed following PRISMA guidelines, and the following data were extracted from included studies: study characteristics, demographics, and outcomes. Bias was assessed using the Cochrane tool. Heterogeneity and effect sizes were analysed using I2 statistics and appropriate effects models. The study protocol was registered with PROSPERO (registration No. CRD42024578243). RESULTS: Six randomized controlled trials met the inclusion criteria (I2 = 0.0%). The meta-analysis indicated a significant improvement in dysphagia with TES (standardized mean difference [SMD] 0.43, 95% confidence interval [CI] 0.13, 0.73). Subgroup analysis suggested that low-intensity TES was effective (SMD 0.46, 95% CI 0.09, 0.82), whereas high-intensity TES showed no significant improvement (SMD 0.37, 95% CI -0.17, 0.91). No publication bias was detected. CONCLUSION: TES may improve swallowing in stroke patients, with potential benefits from low-intensity protocols.

Electrochemically-Switched Microwave Response of MXene in Organic Electrolyte.

The increasingly complex electromagnetic (EM) environment necessitates advanced electrically controllable electromagnetic interference (EMI) shielding materials that can adapt to varying EM conditions. This study develops a flexible electrochemically tunable EMI shielding device based on ultrathin Ti3C2Tx MXene films, exhibiting reversible shielding effectiveness (SE) modulation from 18.9 to 26.2 dB in X band at 0.1 and -1.5 V. Unlike the previously reported mechanism relying on interlayer spacing adjustments, the work leverages transformations of charging state and surface chemistry for tunability during the electrochemical process. The Ti3C2Tx flake size is also evidenced to play a crucial role, with smaller flakes offering higher absorption modulation despite lower SE modulation, enabling the device with high designability. When integrated with Salisbury screen structure, the device achieves adjustable absorption from 93.560% at 0.1 V to 99.996% at -1 V, showing a tunable reflection suppression ratio up to 32 dB with an effective bandwidth of 4.2 GHz. Additionally, incorporating resonant cavity structure enables absorption-dominated (over 90%) microwave-responsive switching at 0.1 and -1.5 V. This work highlights significant potential of adaptive EMI shielding materials for applications in smart electronic protection, EM switch, and radar camouflage.

Prophylactic application of dexmedetomidine reduces the incidence of Emergence delirium in children: A systematic review and Meta-analysis.

BACKGROUND: Emergence delirium (ED) is a common postoperative cognitive dysfunction in children. ED may cause distress to patients and their families in the early post-anesthesia period and have long-term adverse effects on children. THE PRIMARY PURPOSE: was to verify whether dexmedetomidine can reduce the occurrence of ED in children. RESEARCH TYPE: Systematic review and meta-analysis of RCTs. DATA ACQUISITION: A search was conducted on Web of Science, WHO Trials, Cochrane Library, Clinical Trials.gov, and PubMed for all published studies from inception to 23 Oct.2022. ELIGIBILITY CRITERIA: Randomized clinical trials that met the following criteria: patients aged 1-18 years, study site in the PACU (Post-anesthesia care unit), incidence of ED as the primary outcome, and prophylactic use of dexmedetomidine defined as injected before admission to the PACU. RESULTS: A total of 7 randomized trials were included (6 studies during eye and neck surgery, 1 during hernia surgery), involving 512 patients (257 (50.1%) with dexmedetomidine, and 250 (49.9%) with control. ED was observed in 17.51% of the patients treated with dexmedetomidine and in 43.14% of those receiving control (risk ratio (RR) = 0.40, 95 % confidence interval [CI] [0.30 - 0.55], P < 0.00001). Additionally, the prophylactic application of dexmedetomidine also reduced the occurrence of Post-Operating Nausea and Vomiting (RR = 0.24, 95%CI [0.12 - 0.49], P = 0.0001) and PACU stay time after extubation (mean difference (MD) = -1.57, 95%CI [-3.07 to -0.07], P = 0.04). However, sensitivity analysis of RCTs showed that our effect estimates were not stable (MD = -1.78, 95%CI [-4.18 - 0.62], P = 0.15). CONCLUSION: The prophylactic use of dexmedetomidine was associated with a reduction of ED. However, our findings only apply to eye and neck surgery. TRIAL REGISTRATION: PROSPERO: CRD42022371840.

Data-free knowledge distillation via generator-free data generation for Non-IID federated learning.

Data heterogeneity (Non-IID) on Federated Learning (FL) is currently a widely publicized problem, which leads to local model drift and performance degradation. Because of the advantage of knowledge distillation, it has been explored in some recent work to refine global models. However, these approaches rely on a proxy dataset or a data generator. First, in many FL scenarios, proxy dataset do not necessarily exist on the server. Second, the quality of data generated by the generator is unstable and the generator depends on the computing resources of the server. In this work, we propose a novel data-Free knowledge distillation approach via generator-Free Data Generation for Non-IID FL, dubbed as FedF2DG. Specifically, FedF2DG requires only local models to generate pseudo datasets for each client, and can generate hard samples by adding an additional regularization term that exploit disagreements between local model and global model. Meanwhile, FedF2DG enables flexible utilization of computational resources by generating pseudo dataset locally or on the server. And to address the label distribution shift in Non-IID FL, we propose a Data Generation Principle that can adaptively control the label distribution and number of pseudo dataset based on client current state, and this allows for the extraction of more client knowledge. Then knowledge distillation is performed to transfer the knowledge in local models to the global model. Extensive experiments demonstrate that our proposed method significantly outperforms the state-of-the-art FL methods and can serve as plugin for existing Federated Learning methds such as FedAvg, FedProx, etc, and improve their performance.

Sex differences in the association between Body Mass Index and cognitive function in Parkinson disease: a cross-sectional study.

Objective: This study utilized a binary logistic regression model to explore the relationship between Body Mass Index (BMI) and cognitive function in Parkinson's disease (PD) patients. Methods: In this cross-sectional study, data were obtained from 1,005 Parkinson's patients enrolled in the Parkinson's Progression Markers Initiative (PPMI) from 2010 to 2023, including 378 females and 627 males. Cognitive function was assessed using the Montreal Cognitive Assessment (MoCA) scale, and the correlation between BMI and cognitive function was determined using binary logistic regression. Results: The median age of enrollment was 63.6 (56.2, 69.6) years old, including 378 (37.6%) females and 627 (62.4%) males. In the final adjusted model, a significant positive correlation was found between BMI and the prevalence of cognitive impairment in females (OR = 1.06, 95% CI = 1.01 ~ 1.12, p = 0.022), while no correlation was found in males (OR = 1.03, 95% CI = 0.99 ~ 1.08, p = 0.165). The results after categorizing BMI indicate that, among females, the risk of cognitive impairment increases for both groups with BMI ≥ 30 kg/m2 and those with 25 ≤ BMI < 30 kg/m2 compared to the reference group with BMI < 25 kg/m2, with a p for trend <0.001 indicating a stable and strong association between BMI and cognitive impairment in females. In males, the results were not significant. The trend of linear fitting was consistent with the above results. Conclusion: In female Parkinson's patients, there is a positive correlation between BMI and cognitive impairment, while no correlation was found in male patients. This study provides new evidence of sex differences in the correlation between BMI and cognitive impairment among Parkinson's patients. The role of sex differences in the relationship between BMI and cognitive impairment should be considered in future research.

Progress and Prospects of Microplastic Biodegradation Processes and Mechanisms: A Bibliometric Analysis.

In order to visualize the content and development patterns of microplastic biodegradation research, the American Chemical Society (ACS), Elsevier, Springer Link, and American Society for Microbiology (ASM) were searched for the years 2012-2022 using Citespace and VOSvivewer for bibliometrics and visual analysis. The biodegradation processes and mechanisms of microplastics were reviewed on this basis. The results showed a sharp increase in the number of publications between 2012 and 2022, peaking in 2020-2021, with 62 more publications than the previous decade. The University of Chinese Academy of Sciences (UCAS), Northwest A&F University (NWAFU), and Chinese Academy of Agricultural Sciences (CAAS) are the top three research institutions in this field. Researchers are mainly located in China, The United States of America (USA), and India. Furthermore, the research in this field is primarily concerned with the screening of functional microorganisms, the determination of functional enzymes, and the analysis of microplastic biodegradation processes and mechanisms. These studies have revealed that the existing functional microorganisms for microplastic biodegradation are bacteria, predominantly Proteobacteria and Firmicutes; fungi, mainly Ascomycota; and some intestinal microorganisms. The main enzymes secreted in the process are hydrolase, oxidative, and depolymerization enzymes. Microorganisms degrade microplastics through the processes of colonization, biofilm retention, and bioenzymatic degradation. These studies have elucidated the current status of and problems in the microbial degradation of microplastics, and provide a direction for further research on the degradation process and molecular mechanism of functional microorganisms.

In2O3/ZnO heterojunction thin film transistor for high recognition accuracy neuromorphic computing and optoelectronic artificial synapses.

Solid electrolyte-gated transistors exhibit improved chemical stability and can fulfill the requirements of microelectronic packaging. Typically, metal oxide semiconductors are employed as channel materials. However, the extrinsic electron transport properties of these oxides, which are often prone to defects, pose limitations on the overall electrical performance. Achieving excellent repeatability and stability of transistors through the solution process remains a challenging task. In this study, we propose the utilization of a solution-based method to fabricate an In2O3/ZnO heterojunction structure, enabling the development of efficient multifunctional optoelectronic devices. The heterojunction's upper and lower interfaces induce energy band bending, resulting in the accumulation of a large number of electrons and a significant enhancement in transistor mobility. To mimic synaptic plasticity responses to electrical and optical stimuli, we utilize Li+-doped high-k ZrOxthin films as a solid electrolyte in the device. Notably, the heterojunction transistor-based convolutional neural network achieves a high accuracy rate of 93% in recognizing handwritten digits. Moreover, our research involves the simulation of a typical sensory neuron, specifically a nociceptor, within our synaptic transistor. This research offers a novel avenue for the advancement of cost-effective three-terminal thin-film transistors tailored for neuromorphic applications.

Motor dysfunction in Parkinson's patients: depression differences in a latent growth model.

Objective: This study aims to utilize latent growth model (LGM) to explore the developmental trajectory of motor dysfunction in Parkinson's disease (PD) patients and investigate the relationship between depression and motor dysfunction. Methods: Four-year follow-up data from 389 PD patients were collected through the Parkinson's Progression Marker Initiative (PPMI). Firstly, a univariate LGM was employed to examine the developmental trajectory of motor dysfunction in PD patients. Subsequently, depression levels were introduced as covariates into the model, and depression was further treated as a parallel growth latent variable to study the longitudinal relationship between motor dysfunction and depression. Results: In the trajectory analysis of motor dysfunction, the fit indices for the quadratic growth LGM model were χ2 = 7.419, df = 6, CFI = 0.998, TLI = 0.997, SRMR = 0.019, and RMSEA = 0.025, indicating that the growth trend of motor dysfunction follows a quadratic curve rather than a simple linear pattern. Introducing depression symptoms as time-varying covariates to explore their effect on motor dysfunction revealed significant positive correlations (ß = 0.383, p = 0.026; ß = 0.675, p < 0.001; ß = 0.385, p = 0.019; ß = 0.415, p = 0.014; ß = 0.614, p = 0.003), suggesting that as depression levels increase, motor dysfunction scores also increase. Treating depression as a parallel developmental process in the LGM, the regression coefficients for depression intercept on motor dysfunction intercept, depression slope on motor dysfunction slope, and depression quadratic factor on motor dysfunction quadratic factor were 0.448 (p = 0.046), 1.316 (p = 0.003), and 1.496 (p = 0.038), respectively. These significant regression coefficients indicate a complex relationship between depression and motor dysfunction, involving not only initial level associations but also growth trends over time and possible quadratic effects. Conclusion: This study indicates a quadratic growth trajectory for motor dysfunction in PD, suggesting a continuous increase in severity with a gradual deceleration in growth rate. The relationship between depression and motor dysfunction is complex, involving initial associations, evolving trends over time, and potential quadratic effects. Exacerbation of depressive symptoms may coincide with motor function deterioration.

Exploring the impact of N4-acetylcytidine modification in RNA on non-neoplastic disease: unveiling its role in pathogenesis and therapeutic opportunities.

RNA modifications include not only methylation modifications, such as m6A, but also acetylation modifications, which constitute a complex interaction involving "writers," "readers," and "erasers" that play crucial roles in growth, genetics, and disease. N4-acetylcytidine (ac4C) is an ancient and highly conserved RNA modification that plays a profound role in the pathogenesis of a wide range of diseases. This review provides insights into the functional impact of ac4C modifications in disease and introduces new perspectives for disease treatment. These studies provide important insights into the biological functions of post-transcriptional RNA modifications and their potential roles in disease mechanisms, offering new perspectives and strategies for disease treatment.

Electroacupuncture improves the learning and memory abilities of rats with PSCI by attenuating the TLR4/NF-κB/NLRP3 signaling pathway on the hippocampal microglia.

This study aims to investigate how electroacupuncture regulates the learning and memory abilities of poststroke cognitive impairment (PSCI) rats through the TLR4/NF-κB/NLRP3 signaling pathway on the hippocampal microglia. Thirty male rats were randomly divided into three groups: sham surgery group, PSCI model group, and electroacupuncture group, with 10 rats in each group. Middle cerebral artery occlusion was used to establish the PSCI model. The Zea Longa method was used to score the rats' neurological function. Electroacupuncture was utilized for 21 days to improve PSCI. The learning and memory abilities of rats were tested using the Morris water maze. Hematoxylin-eosin staining and immunofluorescence were used to find the hippocampus' pathological changes. The concentration of interleukin-1ß, interleukin-6, tumor necrosis factor-α, and interleukin-18 were detected by ELISA. The mRNA expression levels of associated inflammatory corpuscles were measured by quantitative real-time PCR. The protein expression levels of TLR4, MyD88, NF-κB, and NLRP3 were measured using western blotting. Electroacupuncture improved not only the learning and memory abilities of PSCI rats but also hippocampal morphology. Electroacupuncture inhibited the activation of microglia and the TLR4/NF-κB/NLRP3 signaling pathway. Electroacupuncture also reduced proinflammatory factors and restrained the mRNA levels of NLRP3-associated inflammatory cytokines. Its mechanism was related to inhibiting the expression of the TLR4/NF-κB/NLRP3 signaling pathway, attenuating the release of inflammatory factors, and regulating the activation of hippocampal microglia in the brain.

Association Between Preeclampsia and Blood Pressure in Offspring: A Systematic Review and Meta-Analysis.

PURPOSE OF REVIEW: Pregnancy-induced preeclampsia is a severe pregnancy complication and preeclampsia has been associated with an increased risk of chronic hypertension for offspring. However, the magnitude of the overall effect of exposure to preeclampsia in pregnancy on blood pressure (BP) in offspring is unknown. This systematic review and meta-analysis was sought to systematically assess the effects of preeclampsia on the BP of the offspring. RECENT FINDINGS: Of 2550 publications identified, 23 studies were included. The meta-analysis indicated that preeclampsia increases the potential risk of hypertension in offspring. Systolic blood pressure (SBP) was 2.0 mm Hg (95% CI: 1.2, 2.8) and diastolic blood pressure (DBP) was 1.4 mm Hg (95% CI: 0.9, 1.9) higher in offspring exposed to pre-eclampsia in utero, compared to those born to normotensive mothers. The correlations were similar in stratified analyses of children and adolescents by sex, geographic area, ages, and gestational age. During childhood and young adulthood, the offspring of pregnant women with preeclampsia are at an increased risk of high BP. It is crucial to monitor their BP.

Puerarin Affects 1HMR Spectroscopy Quantified Hepatic Fat Signal Fraction in Intrauterine Growth Restricted Rats.

OBJECTIVE: This study aimed to investigate the impact of puerarin early intervention on growth parameters and Hepatic Fat Signal Fraction (HFF) quantification in Intrauterine Growth Restricted(IUGR)rats through Proton Magnetic resonance spectroscopy (1H-MRS). METHODS: Pregnant rats were divided into three groups: control, IUGR with puerarin treatment, and IUGR without treatment. The treatment and nontreatment groups were received a low-protein diet during pregnancy, while the control group received a normal diet. After birth, pups in the treatment group received a unilateral intraperitoneal injection of 50 mg/kg/d puerarin. Male rats were evaluated at 3,8 and 12 weeks, including measurements of weight, body length and waist circumference and body mass index (BMI). Conventional magnetic resonance imaging and 1HMRS were conducted using a 3.0 T whole-body MR scanner. RESULTS: Newborn pups in the treatment and non-treatment groups showed significantly lower body weight, BMI, and body length at 3 weeks compared to the control group. However, there were no significant differences in HFF and waist circumference between the three groups at 3 weeks. At 8 and 12 weeks post-delivery, significant differences in body weight, BMI, waist circumference were observed in newborn pups of IUGR non-treatment rats compared to the control group. In contrast, there were no significant differences in body weight, BMI, waist circumference between the treatment group and the control group at 8 and 12 weeks. Moreover, the treatment group exhibited notably higher HFF compared to the control group at both time points. At 12 weeks post-birth, a significant difference in HFF was observed between the IUGR non-treatment and treatment groups, although no significant difference was found at 8 weeks. CONCLUSION: Early intervention with puerarin following birth has a significant impact on liver fat content and may potentially reduce adult obesity among IUGR rats.

Laser-Guided, Self-Confined Graphitization for High-Conductivity Embedded Electronics.

Facile fabrication of highly conductive and self-encapsulated graphene electronics is in urgent demand for carbon-based integrated circuits, field effect transistors, optoelectronic devices, and flexible sensors. The current fabrication of these electronic devices is mainly based on layer-by-layer techniques (separate circuit preparation and encapsulation procedures), which show multistep fabrication procedures, complicated renovation/repair procedures, and poor electrical property due to graphene oxidation and exfoliation. Here, we propose a laser-guided interfacial writing (LaserIW) technique based on self-confined, nickel-catalyzed graphitization to directly fabricate highly conductive, embedded graphene electronics inside multilayer structures. The doped nickel is used to induce chain carbonization, which firstly enhances the photothermal effect to increase the confined temperature for initial carbonization, and the generated carbon further increases the light-absorption capacity to fabricate high-quality graphene. Meanwhile, the nickel atoms contribute to the accelerated connection of carbon atoms. This interfacial carbonization inherently avoids the exfoliation and oxidation of the as-formed graphene, resulting in an 8-fold improvement in electrical conductivity (~20,000 S/m at 7,958 W/cm2 and 2 mm/s for 20% nickel content). The LaserIW technique shows excellent stability and reproducibility, with ±2.5% variations in the same batch and ±2% variations in different batches. Component-level wireless light sensors and flexible strain sensors exhibit excellent sensitivity (665 kHz/(W/cm2) for passive wireless light sensors) and self-encapsulation (<1% variations in terms of waterproof, antifriction, and antithermal shock). Additionally, the LaserIW technique allows for one-step renovation of in-service electronics and nondestructive repair of damaged circuits without the need to disassemble encapsulation layers. This technique reverses the layer-by-layer processing mode and provides a powerful manufacturing tool for the fabrication, modification, and repair of multilayer, multifunctional embedded electronics, especially demonstrating the immense potential for in-space manufacturing.

Ferroelectricity-Defects Synergistic Artificial Synapses for High Recognition Accuracy Neuromorphic Computing.

The ability of ferroelectric memristors to modulate conductance and offer multilevel storage has garnered significant attention in the realm of artificial synapses. On one hand, the resistance change of ferroelectric memristors mainly depends on the polarization reversal. On the other hand, the defects such as oxygen vacancies, which are inevitable presence during high-temperature processes, can undergo diffusion drift with the polarization reversal, thereby change the interface potential barrier. Thus, it is both desirable and necessary to investigate the synergistic effect of ferroelectricity and defects. Here, we prepare BaTiO3 ferroelectric memristor by pulse laser deposition and achieve resistance switching through the synergistic effect of ferroelectricity and oxygen vacancies. The memristor shows excellent switching characteristics with a large switching ratio (104) and good stability (103 s). It effectively emulates the features of artificial synapses and accomplishes decimal logical neural computing. In the neuromorphic system crafted with the memristor, the recognition accuracy of the 28 × 28 pixel image reaches 94.9%. These findings strongly support the research of ferroelectric memristors in neuromorphic devices.

3D Printed Room Temperature Phosphorescence Materials Enabled by Edible Natural Konjac Glucomannan.

Shaping room temperature phosphorescence (RTP) materials into 3D bodies is important for stereoscopic optoelectronic displays but remains challenging due to their poor processability and mechanical properties. Here, konjac glucomannan (KGM) is employed to anchor arylboronic acids with various π conjugations via a facile B─O covalent reaction to afford printable inks, using which full-color high-fidelity 3D RTP objects with high mechanical strength can be obtained via direct ink writing-based 3D printing and freeze-drying. The doubly rigid structure supplied by the synergy of hydrogen bonding and B─O covalent bonding can protect the triplet excitons; thus, the prepared 3D RTP object shows a striking lifetime of 2.14 s. The printed counterparts are successfully used for 3D anti-counterfeiting and can be recycled and reprinted nondestructively by dissolving in water. This success expands the scope of printable 3D luminescent materials, providing an eco-friendly platform for the additive manufacturing of sophisticated 3D RTP architectures.

Corrigendum: Identifying neutrophil-associated subtypes in ulcerative colitis and confirming neutrophils promote colitis-associated colorectal cancer.

[This corrects the article DOI: 10.3389/fimmu.2023.1095098.].

Migrate demographic group for fair Graph Neural Networks.

Graph Neural networks (GNNs) have been applied in many scenarios due to the superior performance of graph learning. However, fairness is always ignored when designing GNNs. As a consequence, biased information in training data can easily affect vanilla GNNs, causing biased results toward particular demographic groups (divided by sensitive attributes, such as race and age). There have been efforts to address the fairness issue. However, existing fair techniques generally divide the demographic groups by raw sensitive attributes and assume that are fixed. The biased information correlated with raw sensitive attributes will run through the training process regardless of the implemented fair techniques. It is urgent to resolve this problem for training fair GNNs. To tackle this problem, we propose a brand new framework, FairMigration, which is able to migrate the demographic groups dynamically, instead of keeping that fixed with raw sensitive attributes. FairMigration is composed of two training stages. In the first stage, the GNNs are initially optimized by personalized self-supervised learning, and the demographic groups are adjusted dynamically. In the second stage, the new demographic groups are frozen and supervised learning is carried out under the constraints of new demographic groups and adversarial training. Extensive experiments reveal that FairMigration achieves a high trade-off between model performance and fairness.

Argon non-thermal plasma treatment promotes the development of rice (Oryza sativa L.) in saline alkali environments.

Soil salinization leads to a reduction in arable land area, which seriously endangers food security. Developing saline-alkali land has become a key measure to address the contradiction between population growth and limited arable land. Rice is the most important global food crop, feeding half of the world's population and making it a suitable choice for planting on saline-alkali lands. The traditional salt-alkali improvement method has several drawbacks. Currently, non-thermal plasma (NTP) technology is being increasingly applied in agriculture. However, there are few reports on the cultivation of salt/alkali-tolerant rice. Under alkaline stress, argon NTP treatment significantly increased the germination rate of Longdao 5 (LD5) rice seeds. In addition, at 15 kV and 120 s, NTP treatment significantly increased the activity of antioxidant enzymes such as catalase and SOD. NTP treatment induced changes in genes related to salt-alkali stress in rice seedlings, such as chitinase and xylanase inhibitor proteins, which increased the tolerance of the seeds to salt-alkali stress. This experiment has expanded the application scope of NTP in agriculture, providing a more cost-effective, less harmful, and faster method for developing salt-alkali-tolerant rice and laying a theoretical foundation for cultivating NTP-enhanced salt-alkali-tolerant rice.

Enhancing fuel characteristics and combustion performance of cellulose-rich straws through CO2-assisted torrefaction.

Cellulose-rich straws of corn and rice were torrefied under carbon dioxide, and the fuel characteristics and combustion performance of the obtained biochar were investigated. A high severity resulted in surface collapse, greater pore volume, elimination of oxygen, elevated calorific value, and improved hydrophobicity in biochar. Following carbon dioxide torrefaction, the cellulose content in solid biochar experienced a slight decrease when the temperature was raised to 220 °C for longer residence durations. At 300 °C, the cellulose content in the biochar was nearly eliminated, while the relative proportion of non-sugar organic matter in corn stover and rice straw increased to 87.40 % and 77.27 %, respectively. The maximum calorific values for biochar from corn and rice straws were 22.38 ± 0.03 MJ/kg and 18.72 ± 0.05 MJ/kg. The comprehensive combustion indexes of rice and corn straw samples decreased to 1.06 × 10-7 and 1.31 × 10-7 after torrefaction at 300 °C, respectively. In addition, the initial decomposition temperatures increased by 38 °C and 45 °C, while the ultimate combustion temperatures rose by 13 °C and 16 °C for corn and rice straws, respectively. These results imply an extended combustion timeframe for the torrefied samples.

Selectively fractionate hemicelluloses with high molecular weight from poplar thermomechanical pulp by tetramethylammonium hydroxide.

Selective fractionation of hemicelluloses is of great significance for realizing high-value application of hemicelluloses and comprehensive utilization of lignocellulosic biomass. Tetramethylammonium hydroxide (TMAH) solvent has been confirmed as a promising solvent to selectively fractionate hemicelluloses from holocellulose. Herein, TMAH solvent was adopted to pretreat poplar thermomechanical pulp (PTMP) for the selective fractionation of hemicelluloses and enhancement of enzymatic hydrolysis performance of residues. The maximal hemicelluloses yield (65.0 %) and excellent cellulose retention rate (93.3 %) were achieved after pretreatment by the 25 wt% TMAH solvent, while the delignification was only 33.9 %. The hemicelluloses fractions could be selectively fractionated with high molecular weights (109,800-118,500 g/mol), the contents of Klason lignin in them were low (3.2-5.9 %), and the dominating structure of them was 4-O-methylglucurono-ß-D-xylan. Compared to the H2SO4 and NaOH methods, the hemicelluloses fractionated by TMAH method exhibited higher yields, more complete structures and higher molecular weights. Furthermore, the crystalline structure of cellulose practically remained stable, and the highest yield of enzymatic hydrolysis glucose was 57.5 %, which was 3.3 times of that of PTMP. The fractionation effectiveness of TMAH solvent was not significantly reduced after repeatedly recycling. This work demonstrated TMAH solvent could selectively fractionate hemicelluloses from PTMP and efficiently promote sustainable poplar-based biorefinery.