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Jia-Li Zhang,1,2,&ast; An-Xin Wang,1,2,&ast; Yang Yang,2,3 Qin Xu,1,2 Xiao-Ling Liao,1,2 Wei-Guo Ma,4 Ning Zhang,2,3 Chun-Xue Wang,2,3,5 Yong-Jun Wang1,2 1Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, People’s Republic of China; 2China National Clinical Research Center for Neurological Diseases, Beijing Tiantan Hospital, Capital Medical University, Beijing, People’s Republic of China; 3Department of Neuropsychiatry and Behavioral Neurology and Clinical Psychology, Beijing Tiantan Hospital, Capital Medical University, Beijing, People’s Republic of China; 4Beijing Anzhen Hospital, Capital Medical University, Beijing, People’s Republic of China; 5Beijing Institute of Brain Disorders, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing, People’s Republic of China&ast;These authors contributed equally to this workCorrespondence: Ning Zhang; Chun-Xue Wang, Beijing Tiantan Hospital, 119 South 4th Ring West Road, Beijing, 100070, People’s Republic of China, Emails 827582777@qq.com; snowsen@126.comBackground: Although sleep disorders significantly increase the risk of cognitive impairment, literature is relatively scarce regarding the impact of sleep status on cognitive function in patients with acute ischemic stroke (AIS). We seek to study the association between pre-stroke subjective sleep status and cognitive function at 3 months after stroke.Patients and methods: Data were analyzed for 1,759 AIS patients from the Impairment of Cognition and Sleep after Acute Ischemic Stroke or Transient Ischemic Attack in Chinese Patients Study (ICONS). Pre-stroke subjective sleep status was assessed by the Pittsburgh Sleep Quality Index (PSQI) and Epworth Sleepiness Scale (ESS). Greater sleep fragmentation was defined as waking up in the middle of the night or early morning ≥ 3 times a week. Cognitive function was evaluated using the Montreal Cognitive Assessment (MoCA) at 3 months after stroke. Primary endpoint was the incidence of post-stroke cognitive impairment (PSCI) at 3 months after stroke. The association between subjective sleep status and PSCI was evaluated using multivariable logistic regression.Results: PSCI occurred in 52.1% at 3 months after stroke. Patients with very bad sleep quality before stroke were at increased risk of PSCI (OR, 2.11; 95% CI, 1.11– 4.03; P=0.03). Subgroup analysis found that the association between very bad sleep quality and PSCI was more evident among patients with high school education or above (OR, 5.73; 95% CI, 1.92– 17.10; P for interaction=0.02). In addition, patients with greater sleep fragmentation before stroke were also at higher risk of PSCI (OR, 1.55; 95% CI, 1.20– 2.01; P< 0.01). Similarly, subgroup analysis showed that the risk of PSCI was more pronounced among patients without employment (OR, 2.45; 95% CI, 1.59– 3.77; P for interaction=0.01).Conclusion: Very bad sleep quality and greater sleep fragmentation before stroke were identified as independent risk factors for PSCI at 3 months after stroke.Keywords: subjective sleep status, cognitive impairment, ischemic stroke

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Xiao-Wei Fan,1– 4,&ast; Yang Yang,2– 5,&ast; Shuo Wang,2– 5 Yi-Jun Zhang,1– 4 An-Xin Wang,1– 4 Xiao-Ling Liao,1– 4 Wei-Guo Ma,6 Ning Zhang,2– 5 Chun-Xue Wang,2– 5,7 Yong-Jun Wang1– 4 1Department of Neurology, Capital Medical University, Beijing, People’s Republic of China; 2Center of Stroke, Beijing Institute for Brain Disorders, Beijing Tiantan Hospital, Capital Medical University, Beijing, People’s Republic of China; 3China National Clinical Research Center for Neurological Diseases, Beijing, People’s Republic of China; 4Beijing Key Laboratory of Translational Medicine for Cerebrovascular Disease, Beijing Tiantan Hospital, Capital Medical University, Beijing, People’s Republic of China; 5Department of Neuropsychiatry and Behavioral Neurology and Clinical Psychology, Capital Medical University, Beijing, People’s Republic of China; 6Beijing Anzhen Hospital, Capital Medical University, Beijing, People’s Republic of China; 7Beijing Institute of Brain Disorders, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing, People’s Republic of China&ast;These authors contributed equally to this workCorrespondence: Ning Zhang; Chun-Xue Wang, Beijing Tiantan Hospital, 119 South 4th Ring West Road, Beijing, 100070, People’s Republic of China, Tel +86-15801203052 ; +86-13701193710, Email 827582777@qq.com; snowsen@126.comPurpose: The impact of poor sleep quality after stroke, especially persistent poor sleep quality, on poststroke anxiety and depression is unclear. We seek to investigate the impact of baseline and persistent poor sleep quality on short-term poststroke anxiety and depression.Patients and Methods: Data were analyzed for 1619 patients with acute ischemic stroke from the Impairment of Cognition and Sleep after Acute Ischemic Stroke or Transient Ischemic Attack in Chinese Patients study (ICONS). The sleep quality was assessed at 2 weeks and 3 months using the Pittsburgh Sleep Quality Index scale (PSQI). Poor sleep quality was defined as a PSQI score of > 5, and persistent poor sleep quality was defined as a PSQI score of > 5 at each time point. Patients were divided into three groups according to the quality of sleep: good sleep quality, baseline poor sleep quality and persistent poor sleep quality. Patient Health Questionnaire-9 (PHQ-9), General Anxiety Disorder-7 scale (GAD-7), and Modified Rankin Scale (mRS) at 3 months after stroke were taken as the study outcomes.Results: Persistent poor sleep quality was present in 70.2% of patients after stroke. Compared to those with good sleep quality, patients with baseline poor sleep quality did not show significant differences in disability, anxiety and depression. However, patients with persistent poor sleep were at increased risk of depression (odds ratio, OR 3.04, 95% confidence interval, CI 1.66– 5.57, P < 0.01) and anxiety (OR 3.20, 95% CI 1.42– 7.19, P < 0.01) at 3 months after stroke. Persistent poor sleep quality was not identified as a risk factor for functional disability at 3 months.Conclusion: Patients with persistent poor sleep quality are at added risks for depression and anxiety after stroke.Keywords: sleep quality, depression, anxiety, ischemic stroke

To study the effect of the combination treatment of ginkgo biloba extract and low-frequency repetitive transcranial magnetic stimulation (LF-rTMS) on the oxidative stress and brain neurotransmitters of patients who had cerebral ischemic stroke (CIS).A retrospective analysis was conducted, and 93 CIS patients admitted to the Sichuan Academy of Medical Sciences/Sichuan Provincial People's Hospital from January 2018 to January 2020 were included in the study. They were divided into three groups, the regular treatment group (31 cases), the LF-rTMS group (31 cases), and the combination treatment group (31 cases). Patients in the regular treatment group were given the conventional drug therapy and exercise regimen. The LF-rTMS group received LF-rTMS therapy (for 20-30 min each time, 1 time/d and 5 times/week) in addition to the treatment given to the regular treatment group. The combination treatment group was given ginkgo biloba extract (intravenous drips, once per day) in addition to the treatment given to the LF-rTMS group. The treatment was given continuously for 4 weeks and comparison was made at the end of the 4-week treatment regarding the clinical efficacy, oxidative stress response, cerebral oxygen metabolism, and brain neurotransmitter as shown by the three groups.The treatment efficacy in the combination treatment group (96.77%) was higher than those of the LF-rTMS group (80.65%) and the regular treatment group (54.84%). The LF-rTMS group showed higher treatment efficacy than that of the regular group. The serum superoxide dismutase (SOD) of the combination treatment group was higher than that of the LF-rTMS group and that of the routine group, while the malondialdehyde (MDA) and endothelin-1 (ET-1) of the combination treatment group were lower than those of the LF-rTMS group and the regular treatment group (The combination treatment of ginkgo biloba extract and LF-rTMS helped to improve the clinical outcome of CIS patients, which may be related to the inhibition of oxidative stress, improvement in cerebral oxygen metabolism, and regulation of brain neurotransmitter.

BACKGROUND Recently, the negative effects of the COVID-19 pandemic on mental health have been addressed from the perspective of general public health. The role of problematic Internet use as a risk factor for psychological distress during the epidemic is another area of increased concern. Preliminary evidence suggests an increased psychological vulnerability for elementary and middle school teachers. OBJECTIVE The current study analyzed the role of problematic Internet use, including problematic smartphone (PSU) and problematic social media use (PSMU), as explanatory variables in terms of primary and middle school teachers’ fear of COVID-19. The effects of PNT of online teaching and fear of COVID-19 were also evaluated in terms of teachers’ psychological distress. The purpose was to empirically evaluate the relationships among these research variables using a proposed model of factors contributing to teachers’ psychological distress during COVID-19. METHODS Online survey data was collected from 9030 primary and middle school teachers. A conventional model based on recent publications in the field of problematic Internet use and psychological distress during COVID-19 was compared with a proposed model, based on prior findings indicating problematic Internet use variables serve as explanatory, rather than outcome, variables. RESULTS Structural Equation Modelling confirmed the superior goodness of fit of the proposed model (Χ2 (348) = 6220.27, RMSEA = 0.04, NNFI = 0.07, CFI = 0.99, SRMR = 0.07), as evidenced by aΔAIC of 578.505 (significant when greater than 10) between the conventional model and proposed model. The data also demonstrated that the proportion of participants with psychological distress was relatively high: depression (20.4%), anxiety (26.4%), and stress (10.2%). The problematic Internet use behaviors were significantly associated with fear of COVID-19 (PSU: t = 17.19, P < 0.001; PSMU: t = 7.91, P < 0.001). Fear of COVID-19 and PNT of online teaching were both positively related with psychological distress (Fear of COVID-19: t = 9.65, P < 0.001; PNT of online teaching: t = 10.83, P < 0.001). A significant moderating effect was found for PNT of online teaching on psychological distress (t = 5.68, P < 0.001), in that PNT of online teaching enhances the harmful effect of fear of COVID-19 on psychological distress. CONCLUSIONS The findings suggest that problematic Internet use behaviors contribute to fear of COVID-19 which, in turn, results in psychological distress. PNT of online teaching was both directly associated with increased psychological distress as well as serving as a moderator enhancing the impact of fear of COVID-19 on psychological distress. We suggest that school administrators pay attention to teachers’ psychological needs and make efforts to assist teachers in experiencing greater autonomy and relatedness from interpersonal relationships to alleviate the psychological need thwarting that may arise from online teaching tasks.

Making osteoblast migration manageably target to injury sites has been the key challenging in cell therapy for bone and cartilage regeneration. Superparamagnetic materials, the magnetic guide for cell migration, have been applied to increase cell retention. However, additional targeting modifications are still needed to accelerate the low uptake efficiency and moving speed. Arg-Gly-Asp peptide (RGD)-functionalized magnetic nanoparticles showed cutting-edge competence in cell differentiation control and targeted drug delivery. However, more evidence was required to corroborate its role in osteoblast migration in bone repair. In the present study, RGD-modified

High-throughput drug screening microfluidic chip has good biocompatibility and faveriable functional integration, which is the excellent platform for high-throughput screening. Importantly, FRET (Fluorescence Resonance Energy Transfer) technology is the most efficient detection means at present. In this paper, we introduce the development of drug screening microfluidic chip on cellular level and the application of FRET technology on cell detection. Further, we discusse the possibility of FRET applied in the field of microfluidic biochip.

Problematic Internet use (PIU) is a risk factor for psychological distress during COVID-19, as teachers are a psychologically vulnerable population. We explored the role of PIU in terms of primary and middle school teachers’ fear of COVID-19 and psychological need thwarting (PNT) of online teaching. We empirically evaluated the relationships among these research variables in explaining teachers’ psychological distress during COVID-19. Online survey data were collected from 9,030 teachers. A high proportion of participants demonstrated psychological distress: depression (20.4%), anxiety (26.4%), and stress (10.2%). Structural equation modeling was used to test our proposed conceptual model, wherein PIU behaviors served as predictors, mediated by fear of COVID-19 and PNT of online teaching, for teachers’ psychological distress. With ideal model fit, the results of the path coefficients indicated that PIU behaviors were associated with fear of COVID-19 (p &lt, 0.001), fear of COVID-19 and PNT of online teaching were associated with psychological distress (p &lt, and fear of COVID-19 was also positively associated with PNT of online teaching (p &lt, 0.001). PSU and PSMU had an indirect positive effect on psychological distress through the mediator of fear of COVID-19 and PNT of online teaching. As such, we suggest that school administrators pay greater attention to teachers’ psychological needs through efforts to enhance teachers’ autonomy and relatedness from interpersonal relationships, alleviating PNT of online teaching. Our PNT of online teaching scale may also serve as a contribution for further research and practice.

Sr4Al14O25:Eu2+, Dy3+ luminescent phosphor was synthesized for the first time from using cyclodextrin as chelating agent by sol-gel method. The structural characterization, surface morphology and properties of the phosphor were studied. The results revealed that the target phosphor with relatively regular morphology, smaller grain size, pure phase and high crystallinity can be achieved at 1200°C for 4 h in a reducing atmosphere. The average grain size of the Sr4Al14O25:Eu2+, Dy3+ phosphor nanoparticles ranges from 50 to 100 nm . And the phosphorescence in blue-green (483 nm) by Eu2+.

The microenvironment has been shown to regulate cellular functions including cell growth, differentiation, proliferation, migration, cancer development and metastasis. However, the underlying mechanism remains largely unclear. It has been reported that tension force is a key issue for osteogenesis of human mesenchymal stem cells (MSCs) and osteoblasts. In the present study, fibronectin film covered on glass substrate was made into square-shaped micro patterns. Osteoblasts cultured on this geometric substrate first located at the edge of the square. Next day the cells extended to the whole square. The results showed that geometric cues can control the growth of osteoblasts. Possible explanation is that the edge of the square provides higher tension force to the cell. These findings demonstrate that tension force from geometric shape is a positive signal for osteogenesis of osteoblasts and bone remodeling.

Chitosan and N,O-carboxymethyl chitosan are non-toxic natural absorbents. In this paper, the adsorbing behavior of Chitosan and O, N-carboxymethyl Chitosan for Co2+ respectively were studied. The result indicated that the adsorbing ability of N,O-carboxymethyl chitosan was better than this of chitosan. The adsorbing ratio increased clearly with the increasing in the pH value of solution and absorbent amount, but it was not sensitive to the concentration of Co2+. Within ten minutes, the adsorbing ratio of above absorbents could achieve above 80%. But with time prolonging, the adsorbing ratio increased slowly. When time was more than 15 minutes and the pH value was higher than 10, the adsorption rate slowly flatted out.

Carbon/Carbon composite is considered to be one of the best biomaterials substitute to human hard tissues due to its excellent biocompatibility and the much closed elastic modulus to human skeleton. It has been widely used and studied to the fields of artificial bones materials, but the osteoinductivity need to be improved. In recent years, the commonly used surface modification to improve their bone induction, such as hydroxyapatite, chitosan and so on, which prompted the adsorption of osseous protein, adhesion and growth of cells. It is believed the surface modification and coating of the carbon/carbon composite should promote its application in artificial bones. This article reviews the modified coat of medical carbon / carbon composites in recent years, and proposed some recommendations for the development of medical carbon / carbon composite in the future.

Exploring an effective replacement material of bone transplantation to repair bone defect is the hot topic in bone defect therapy at present. The biomimetic materials will be the main dircetion. Chitosan, the N-deacetylated derivative of chitin, has been regarded as suitable materials because of its biocompatibility, biodegradability, reliability and wide sources, which is the next generation of promising materials for tissue engineering. This study introduce the best CoCl2_-Chitosan-gel-sticks of different concentrations prepared by using the in-situ Precipitation Method and Alternate deposition Method. This investigation progeny will have a wide range of applications in biological materials field and other fields.

SUMMARY Aims With developments of etiology of cerebral small vessel disease (CSVD) and genome-wide association study (GWAS) of stroke, the genetic studies of CSVD are focused on genes related to blood-brain barrier (BBB) and aging. The project aims to investigate the association between CSVD and susceptibility loci and candidate genes. Methods All study subjects admitted Beijing Tiantan Hospital from June 2009 to September 2010 including 197 cerebral small vessel disease patients(S), 198 large artery atherosclerosis control individuals (vascular stenotic rate ≥50% diameter reduction) (L), 200 hypertensive intracerebral hemorrhage control individuals (H) and 197 stroke-free control individuals (C). 15 SNPs in 4 genes (MYLK, AQP4, NINJ2, and INK4/ARF) were genotyped using Multiplex Snapshot assay. Each SNP was first examined between the groups S and C in different genetic models (codominant, dominant, recessive, overdominant, and log-additive). Permutation correction was used to adjust for multiple testing. The significant SNP loci were further analyzed in comparing S with L and H, respectively. Subgroup analysis was also performed for each risk-factor category. Results Among the 15 SNPs, rs2222823 and rs2811712 were found to be significantly associated with CSVD after multiple-testing adjustment. The heterozygote (A/T) of rs2222823 of MYLK has an odds ratio of 0.52 (95% CI =[0.35, 0.79], P= 0.002, adjusted P= 0.031) when compared with homozygotes. The heterozygote (C/T) of rs2811712 of INK4/ARF has an odds ratio of 1.75 (95% CI =[1.13–2.71], P= 0.004, adjusted P= 0.050). The SNP rs2222823 was significant (P= 0.035) in comparing S with H. In comparing S versus L, it is significant for the subgroups of patients without diabetes (P= 0.012) and drinking (P= 0.018). rs2811712 was significant in comparing S with L for the subgroups of patients with hyperlipidemia (P= 0.029) and drinking (P= 0.04). Conclusion The heterozygotes (T/A) at the rs2222823 SNP locus of MYLK gene decreases the risk of having cerebral small vessel disease, while the heterozygotes (C/T) at the rs2811712 SNP locus of INK4/ARF gene increases the risk, suggesting that the MYLK and INK4/ARF are the associated genes of cerebral small vessel disease in Han Chinese population.

Rationale and Objectives To investigate whether baseline apparent diffusion coefficient (ADC) maps can be employed to predict both infarct core and salvageable ischemic tissue volumes in acute ischemic stroke. Materials and Methods An automated image analysis system based on baseline ADC maps was tested against 30 patients with acute ischemic stroke of anterior circulation to predict both infarct core and salvageable ischemic tissue volumes. The predicted infarct core and predicted salvageable ischemic tissue were quantitatively and qualitatively compared with follow-up imaging data in recanalization and no recanalization groups, respectively. Direct comparisons with perfusion- and diffusion- weighted magnetic resonance imaging measures were also made. Wilcoxon signed-rank test, Spearman rank correlation, and Bland-Altman plots were performed. Results In the recanalization group, the predicted infarct core volume was significantly correlated with the final infarct volume (r = 0. 868, P < .001). In the no recanalization group, the predicted final infarct volume (sum of the predicted infarct core and salvageable ischemic tissue volumes), as well as the predicted salvageable ischemic tissue volume, was also significantly correlated with the true final infarct volume (r = 0.955, P < .001) and infarct growth (r = 0.918, P < .001), respectively. The volumes of perfusion-diffusion mismatch were significantly larger than those of infarct growth and predicted salvageable ischemic tissue. Good agreement between predicted and true final infarct lesions was visualized by Bland-Altman plots in two groups. Direct visual comparative analysis revealed good qualitative agreement between the true final infarct and predicted lesions in 21 patients. Conclusion The proposed ADC based approach may be a feasible and practical tool to predict the volumes of infarct core and salvageable ischemic tissue without intravenous contrast media–enhanced perfusion-weighted imaging at baseline.

The polylactic acids (PLA) scaffolds materials have been used to be the scaffolds materials of bone, cartilage gristle, blood vessel, nerve and skin due to its bioactivity, biocompatibility and biodegradable, today, the porous polylactic acid scaffolds had widely applied to tissue engineering. In the paper, the advance in study of microstructure and biocompatibility for this material were summarized. The lack in study of microstructure and compatibility has been pointed out and some viewpoints for further investigations are also made in this paper.

Artificial neural network (ANN) is widely applied to the modeling of complex systems, which has become a common modeling method in the study of materials science. As the ideal candidates for high temperature structural materials, carbon materials are no doubt involved in fatigue loads, so the study on forecasting fatigue life is meaningful. In this paper, the electrical resistance at various fatigue cycles and level of applied stress of the materials under tensile fatigue loading has been detected, and regarded the fracture or fatigue cycles equal to 106 as fatigue life of carbon materials. On the basis of the electrical resistance value, the fatigue life has been forecasted by applied the ANN. The results indicated that the ANN could forecast the fatigue life of carbon materials well; finally, the applications of ANN in the study of material, such as properties prediction, damage prediction and failure detection were reviewed.

As the ideal candidates for high temperature structural materials, carbon/carbon (C/C) composites are no doubt involved in fatigue loading. Therefore, the study on fatigue behavior is meaningful. In this paper, the research on fatigue behavior of C/C composites was reviewed and the characteristic of fatigue behavior was summarized. Some viewpoints for further investigations for the study on the fatigue behavior of C/C composites are also made in this paper.

3D braided C/C composites have been prepared by an isothermal chemical vapor infiltration (CVI) process, and the evolution of flexural behavior perpendicular to the fiber direction after tensile fatigue loads was examined. The results show that the flexural property of C/C composites was enhanced with the increase in fatigue cycles, and the fracture mode also evolved from “brittle” of original samples to “pseudo-plastic” of fatigued samples. It is suggested that the weakened interface and reduced residual thermal stresses by fatigue loads play important roles in enhancing the property of C/C composites.

The bend-bend fatigue behavior of 3D integral braided carbon/carbon composites (3D C/C) was examined. Fatigue test was conducted under load control at a sinu-soidal frequency of 10 Hz to obtain stress-fracture cycles (S-N) relationship. The fatigue limit of the C/C was found to be 203 MPa (92% of the static flexural strength), the lag loops of fatigue load-displacement were transformed from elasticity to anelasticity and the flexibility of specimens were enhanced with increase in applied stress. It is revealed that the interfacial sliding abrasion played an important role in the fatigue failure process, and the extent and speed of sliding abrasion were con-trolled by the level of applied stress.

To evaluate the clinical effect and masticatory efficiency of two early loaded Small Diameter Implants (SDI) retained mandibular overdentures.Eight mandibular edentulous patients received two SDIs insertion between mental foramina. The mandibular overdentures were connected with implants for early loading in the period of 2-4 weeks following implant insertion. The data of visual analogue scale (VAS) of denture satisfaction and masticatory ability were collected at baseline, two weeks, three months and six months following overdenture loading. Masticatory efficiency was evaluated before surgery and six months after overdenture loading.Within the period of six months following overdenture loading, all the 16 implants remained stable. Compared with the baseline, the VAS data of denture satisfaction,stability, masticatory and poltophagy ability two weeks, three months and six months after overdenture loading were significantly improved with 30 degree (P0.01), especially the masticatory and poltophagy ability of hard and crisp food. The value of masticatory efficiency improved considerably six months after overdenture loading (P0.01).Mandibular overdentures retained by two SDIs can significantly improve patients' denture satisfaction and masticatory efficiency, and provide more rational diet.

To survey the current availability of expertise in diagnosis and treatment of neurological diseases in grade II hospitals (primary hospitals) in Beijing.Observation, personal in-depth interview and structured questionnaire methods were conducted to survey the status of neurology health care system.From June to August 2005, 66 grade II suburban and urban hospitals in Beijing of China were investigated. There were 66 grade II hospitals in Beijing (suburban 34; urban 32). Cerebrovascular disease was the most common disease. Accounting for 84% of the hospitalized cases in inpatients neurology departments. In urban areas, the proportion of grade II and grade III hospitals (referral hospitals) was 58:60, but in suburban and rural areas, the proportion was 48:6. In suburban and rural areas. Only 64.7% of the hospitals could provide urokinase treatment, 26.5% could provide recombinant tissue plasminogen activator (rt-PA) treatment and 58.8% had standardized operation protocol.The grade II hospitals in suburban areas have heavy grave responsibility to deal with cerebrovascular disease, but these hospitals are in lack of specialists, diagnostic equipment and stroke treatment protocols and could not satisfy the medical demand. It is suggested that in the grade II hospitals in suburban areas of Beijing, strengthening personnel training, establishing primary stroke center and setting up telestroke emergency care systems are urgently needed.

Three dimensional braided carbon/carbon composites (3D C/C composites) were fabricated by chemical vapor infiltration. The thermal expansion behavior of these materials with various densities before and after heat treatment was investigated. It is found that PAN-based carbon fibers (CFs) have an obviously negative coefficient of thermal expansion (CTE) after heat treatment at 1 200 ℃. The CTE of the 3D C/C composites is negative from room temperature to 100 ℃ and is proportion to their density. In the temperature range of 100-1 000 ℃,CTE vs. T curves have an almost a constant slope and expansion behavior of the composite is similar to that of pyrocarbon. When the temperature is above 1 000 ℃,a peak is found in the CTE vs. T curves,indicating that expansion of the pyrocarbon is limited by CFs and the thermal expansion behavior of the composites is determined by both CFs and matrix.