Ultrafast Relaxation Dynamics of Photoexcited Dirac Fermion in The Three Dimensional Dirac Semimetal Cadmium Arsenide

Three dimensional (3D) Dirac semimetals which can be seen as 3D analogues of graphene have attracted enormous interests in research recently. In order to apply these ultrahigh-mobility materials in future electronic/optoelectronic devices, it is crucial to understand the relaxation dynamics of photoexcited carriers and their coupling with lattice. In this work, we report ultrafast transient reflection measurements of the photoexcited carrier dynamics in cadmium arsenide (Cd3As2), which is one of the most stable Dirac semimetals that have been confirmed experimentally. By using low energy probe photon of 0.3 eV, we probed the dynamics of the photoexcited carriers that are Dirac-Fermi-like approaching the Dirac point. We systematically studied the transient reflection on bulk and nanoplate samples that have different doping intensities by tuning the probe wavelength, pump power and lattice temperature, and find that the dynamical evolution of carrier distributions can be retrieved qualitatively by using a two-temperature model. This result is very similar to that of graphene, but the carrier cooling through the optical phonon couplings is slower and lasts over larger electron temperature range because the optical phonon energies in Cd3As2 are much lower than those in graphene

PO-184 Effects of resistance training and aerobic training on Fibronectin of Skeletal Muscle Extracellular Matrix and Satellite Cell in Aging Mice

Objective To investigate the effects of resistance and aerobic training on the content of fibronectin in skeletal muscle extracellular matrix and satellite cell in 9-month-old BALB/c mice, and then explore the effect of fibronectin content change on satellite cell and its intrinsic mechanism, which will provide a new research perspective and theoretical evidence for delaying sarcopenia. Methods 27 one-month-old BALB / c mice of SPF grade were purchased and fed for natural aging. At 9 months of age, the mice were divided into three groups randomly. Group R was resistance exercise training group (n=9), group A was aerobic exercise training group (n=9), and group C was control group (n=9). The load ladder model for resistance training in group R, the pyramid training program for 9 week training, 5 sets of load ladder training every time. 2 min for rest between sets, 1 min for rest between repetitions, 3 times a week. The treadmill training for aerobic training in group A for 9 weeks, the speed of 0.8km/h, 40min every time, 3 times a week. There is no training in group C. During the training, mouse grip strength was tested by the BIOSEB grip instrument once a week. After exercise intervention, the blood of mice was taken from the eyeball, and the gastrocnemius muscles were removed and placed in -80℃ temperature refrigerator to be freezed for tested . Immunofluorescence was used to detect FN and Pax7; The Real-time PCR was used to detect mRNA of FN, Sdc4, Fzd7, Wnt7a, c-Jun, Pax7; Western Blotting was used to detect the FN, sdc4, Fzd7, Wnt7a, c-Jun, p-c-Jun, Pax7 protein content. Results (1) Body weight, grip strength and skeletal muscle mass of mice: The body weight of group C and group R were significantly decreased after 9 weeks to compared with group A (P <0.05; P <0.05). The grip strength of group R and A was significantly increased in the ninth week to compared with group C, (P <0.01; P <0.05); The grip strength of group R and A in the ninth week were significantly higher than that in the first week (P <0.01; P <0.01)；  (2) FN in skeletal muscle extracellular matrix and it’s receptor Sdc4: The integrated optical density (IOD) of FN in group R was higher than that in group C and group A, but there was no significant difference among the three groups. The FN mRNA in group R was significantly increased to compared with group A (P<0.05). The FN protein content in group R was significantly increased to compared with group C and group A (P <0.01; P <0.01). There was no significant difference in the expression of Sdc4 mRNA in gastrocnemius muscle among the three groups. Compared with group C, the Sdc4 protein content was significantly down-regulated in both group R and group A (P<0.01; P<0.05). (3) Wnt7a/PCP signaling pathway: The Wnt7a mRNA and Wnt7a protein content in the gastrocnemius muscle of group R were significantly increased to compared with group C (P<0.05; P<0.01)). Compared with group A, Wnt7a protein content in group R was also significantly increased (P<0.05). There was no significant difference in Fzd7 mRNA in gastrocnemius muscle among the three groups; but the Fzd7 protein content in group R was significantly increased to compared with group A (P<0.05). The c-Jun mRNA in group R was significantly increased to compared with group C and A (P<0.05; P< 0.05). The content of c-Jun protein in group R was significantly increased to compared with group C and group A (P<0.01; P<0.01). The content of p-c-Jun protein in group R was significantly increased to compared with group C (P<0.05). (4) Pax7 : The number of Pax7 positive cells in group R was higher than that in group C and group A, but there was no significant difference among the three groups. Pax7 mRNA in group R and group A were significantly lower than that in group C (P<0.05; P<0.01), but Pax7 protein content in group R was significantly higher than group C and group A (P <0.05; P <0.05) Conclusions (1) Exercise can improve muscle strength of aging mice. (2) Resistance training can promote FN in skeletal muscle extracellular matrix and improve skeletal muscle extracellular matrix components of aging mice. (3) Resistance exercise training can promote Pax7 expression through the increase of FN and up-regulation of Wnt7a / PCP signaling pathway, thus make it possible for satellite cell proliferation

OR-011 Effect of Aerobic and Resistance Exercise on TGF-β1/Smad3 Signal Pathway and Collagen in Skeletal Muscle of Aging Mice

Objective The purpose of this study was to investigate the effects of TGF-β 1/Smad3  signaling pathway and its downstream factor CTGF in collagen deposition and its molecular mechanism. And then it explored further the effect of exercise on the TGF-β1/Smad3 signaling pathway and collagen deposition in skeletal muscle. Therefore, it is expected to provide alternative exercise intervention approaches for skeletal muscle diseases, which are caused by age-related changes of collagen, and to provide new research perspectives for skeletal muscle satellite cell activation and skeletal muscle regeneration. Methods 21 male BALB/c mice were normally raised from 4 weeks to 36 weeks under standard conditions. The mice was divided randomly into three groups, including: group C, the quiet control group; Group A, the aerobics training group, received nine weeks of treadmill training without loading; And the group R, the resistance training group, received nine weeks of climbing training with loading. The body weight and limb grip of the mice were measured on regularly during the experiment. After 24 hours of the last intervention experiment, the mice were weighed and then executed by dislocating the cervical spine. The quadriceps were taken. Real-time PCR technology was used to detect the mRNA levels of TGF-β1, TβR I, Smad 3, CTGF, Pax7, COL1 and COL3. Western blotting technique was used to detect the protein levels of TGF-β1, Smad3, P-Smad3 , CTGF, COL1, COL3, Pax7 and MyoD . The deposition of collagen in the quadriceps muscle tissue of mice was detected by Sirius red staining. And the localization and expressions of COL1 and Pax7 in the quadriceps of mice were demonstrated by immunohistochemistry and immunofluorescence technology respectively. Results (1)       Compared with group C, the weight of mice in group A was significantly increased (P<0.05), and the ratio of the wet weight of the quadriceps and the body weight of the mice increased significantly (P<0.05), while there was no significant change on the limbs relative grip strength. Compared with group C, the body weight of mice in group R showed a certain degree of increase but no significant difference, the ratio between the wet weight of the quadriceps and the body weight of the mice was significantly increased (P<0.01), and the limbs relative grip strength was significantly increased (P<0.05). (2)     Compared with group C, there was no significant difference in the mRNA and protein expression of COL1 and COL3 in the quadriceps of mice in group A, and there was no significant change in collagen volume fraction. Compared with group C, the mRNA and protein expression of COL1 and COL3 of the quadriceps in group R were significantly decreased (P<0.05), and collagen volume fraction significantly reduced (P<0.05), and collagen deposition decreased. (3)     Compared with group C, the mRNA level of CTGF and the protein level of TGF-β1 and CTGF in quadriceps tissues of mice in group A were significantly decreased (P<0.05). While the protein levels of Smad3 and p-Smad3 and the ratio of Smad3 and p-Smad3 had no significant change. Group R is compared with group C, the mRNA level of TGF-β1, TβR I and CTGF in quadriceps were significantly decreased (P<0.05); the mRNA levels of Smad3 and the protein levels of TGF-β1 and p-Smad3 were significantly decreased (P<0.01); and the protein levels of Smad3 and CTGF and the ratio of Smad3 and p-Smad3 were also significantly decreased (P<0.05). (4)     Compared with group C, the mRNA and protein expression of Pax7, and the protein expression of MyoD in the quadriceps of group A showed no significant difference. But group R is compared to group C, the expression of Pax7 mRNA in the quadriceps was significantly increased (P<0.01), and the expression of Pax7 protein was also significantly increased (P<0.05), while the protein expression of MyoD did not change significantly. Compared with group A, the mRNA levels of Pax7 in the quadriceps of the R group was significantly increased (P<0.05), but the protein expression of Pax7 and MyoD showed no significant change. Conclusions (1)     Through 9 week resistance or aerobic exercise training, skeletal muscle mass index in mice increased significantly; and the resistance exercise training can improve the limbs relative grip strength to prevent sacorpenia. (2)     9 week resistance exercise training can inhibit TGF-β1/Smad3 signaling pathway, affect the gene expression of COL1 and COL3, inhibit collagen synthesis, and improve collagen deposition. (3)     9 weeks of resistance exercise training can effectively promote Pax7 gene expression, activate skeletal muscle satellite cells and promote its proliferation. (4)     The effect of 9 week of resistance exercise training on the improvement of skeletal muscle mass, strength, collagen deposition and the activation of satellite cells was significantly better than that of aerobic exercise

Synthesis and self-assembly of tetraphenylethene and biphenyl based AIE-active triazoles

Self-assembly of fluorescent functional materials has attracted increasing interest in the fabrication of optoelectronic and biological nanodevices. Tetraphenylethene (TPE) is a typical dye molecule with aggregation-induced-emission (AIE) characteristics. Melding TPE carrying triple-bond functionality with diazide-containing biphenyl through ''click'' chemistry generates AIE-active luminogens [1,1'-biphenyl]-4,4'-diyl bis(6-(4-(4-(1,2,2-triphenylvinyl)phenyl)-1H-1,2,3-triazol-1-yl) hexanoate) [1(5)] and[1,1'-biphenyl]-4,4'-diyl bis(11-(4-(4-(1,2,2-triphenylvinyl)phenyl)-1H-1,2,3-triazol-1-yl) undecanoate)[1(10)] with solid state efficiencies up to unity. Slow addition of dilute THF solutions of 1(m) (m ¼ 5, 10) into nonsolvents such as n-hexane and water yields self-assembled white wooly solids. TEM and SEM observations reveal the (helical) nanofibrous structure of the aggregates. Upon cooling from their concentrated hot solutions, 1(m) readily precipitate. Meanwhile, they can also form gels at high concentrations. Both precipitates and gels of 1(m) exhibit structures similar to those of the aggregates formed in nonsolvents. These results indicate that 1(m) can facilely self-assemble into high emission efficiency (helical) nanofibers, thus paving the way for their optoelectronic and biological applications

Carbon materials for enhanced photothermal conversion: Preparation and applications on steam generation

Photothermal conversion attracted lots of attention in the past years and sorts of materials were explored to enhance photothermal efficiency. In the past years, solar-driven desalination by photothermal conversion was proposed to release the shortage of fresh water and then it was considered much more important to prepare photothermal materials on large scales with high performance and low cost. In this review, we summarized the works on carbon-based photothermal materials in the past years, including the preparation as well as their application in steam generation. From these works, we give an outlook on the difficulties and chances of how to design and prepare carbon-based photothermal materials