Preparation of super-aligned carbon nanotube-reinforced nickel-matrix laminar composites with excellent mechanical properties

A homogeneous and compact super-aligned carbon nanotube(SACNT)-reinforced nickel-matrix composite was successfully prepared by electrodeposition. The mechanical properties of the laminar SACNT/Ni composites were substantially improved compared with those of pure nickel. With increasing content of SACNTs, the tensile strength of the composite increased and the elongation decreased because of the high-strength SACNTs bearing part of an applied load and the fine-grained strengthening mechanism. The nanohardness of the SACNT/Ni composites was improved from 3.92 GPa(pure nickel) to 4.62 GPa(Ni-4 vol%SACNTs). The uniform distribution of SACNTs in the composites and strong interfacial bonding between the SACNTs and the nickel matrix resulted in an improvement of the mechanical properties of the SACNT/Ni composites. The introduced SACNTs refined the nickel grains, increased the amount of crystal twins, and changed the preferred orientation of grain growth.

Effects of ply-orientation on microstructure and properties of super-aligned carbon nanotube reinforced copper laminar composites

The super-aligned carbon nanotube(SACNT)films reinforced copper(Cu)laminar composites with different orientationsof CNT ply were fabricated by electrodeposition.The results show that the tensile strength and yield strength of cross-ply compositewith5.0%(volume fraction)of SACNT reach maximum of336.3MPa and246.0MPa respectively,increased by74.0%and124.5%compared with pure Cu prepared with the same method.Moreover,the electrical conductivities of all the prepared composites areover75%IACS.The result of TEM analysis shows that the size of Cu grain and the thickness of twin lamellae can be reduced byadding SACNT,and the refining effect in cross-ply composites is more significant than that in unidirectional ply composites.Theenhanced strength of the Cu/SACNT composites comes from not only the reinforcing effect of SACNT films but also the additionalstrengthening of the Cu grain refinement caused by CNT orientation.

电针通过调控ILC2功能和白色脂肪棕色化治疗肥胖大鼠的作用机制

Objective:To observe the effects of electroacupuncture(EA)on type 2 innate lymphoid cell(ILC2)function in white adipose tissue(WAT)of high-fat diet(HFD)-induced obese rats to reveal the mechanism underlying weight loss.Methods:Male Winstar rats(n=15)were randomly divided into control,HFD,and HFD+EA groups,with five rats in each group.An obesity model was established by feeding rats with a HFD.EA(2 Hz,1 mA)was applied to"Zhongwan(CV12)"bilateral"Tianshu(ST25)""Zusanli(ST36)"and"Sanyinjiao(SP6)"for15 min,7 days a week,for a total of 5 weeks.During EA treatment,the HFD group was fed a HFD,whereas rats in the control group were maintained on a normal diet.There was no intervention in either the control or the HFD groups.Body weight was measured weekly.Full-field adipocyte morphology,adipocyte volume,and the number of abdominal WAT were observed under a microscope after sectioning and hematoxylin and eosin staining.The levels of IL-5(interleukin-5),IL-13(interleukin-13),IL-33(interleukin-33),and ST2(growth stimulating gene 2 protein)in the WAT were assayed using enzymelinked immunosorbent assay and reverse transcription-polymerase chain reaction(RT-PCR).The expression levels of browning markers including PGClα(peroxisome proliferator-activated receptor gamma coactivator 1-alpha),PPARγ(peroxisome proliferator-activated receptor gamma),PRDM16(histone-lysine Nmethyltransferase),and UCP1(uncoupling protein 1 in WAT were detected by western blot analysis and RT-PCR.Results:After a 7-week induction period,rats in both the HFD and HFD+EA groups were 20%heavier than their initial weights before modeling(P<0.01,P<0.001).Following a 5-week EA intervention,the body mass and Lee index of obese rats were significantly reduced(P<0.05).The HE results showed that adipocytes in the HFD group displayed a significant increase in diameter and a decrease in number compared to the control group.However,in the HFD+EA group,white adipocytes exhibited reduced diameter and appeared more regular in shape.In the control group,the proportion of ILC2 was(86.53±2.55)%,whereas in the HFD group,it decreased to(73.62±2.52)%,indicating a significant reduction in ILC2 in the WAT of obese rats.Following EA treatment,the proportion of ILC2 was elevated to(80.54±4.25)%.This analysis revealed a significant decrease in the expression levels of IL-5,IL-13,IL-33,and ST2 in the WAT of obese rats in the HFD group;however,these levels increased after EA intervention.The mRNA levels of PPARy,PGC1α,PRDM16,and protein levels of UCP1 were decreased in the HFD group(P<0.01,P<0.05,and P<0.001),and the trends were significantly reversed with EA manipulation(P<0.05).RT-PCR and western blotting results revealed that EA remarkably upregulated the mRNA expression of PGC1α,PPARy,and PRDM16,as well as the protein expression of UCP1 induced by HFD.In the HFD group,PRDM16 expression showed a strong correlation with UCP1 expression,and ILCs were strongly correlated with PGC1αexpression.However,these strong correlations did not occur in HFD+EA group.Following EA treatment,the expression of PPARy displayed a strong correlation with ILC2s,indicating that the altered ILC2 proportion was closely related to browning in WAT.Conclusion:EA treatment effectively alleviated obesity by restoring ILC2 function and promoting browning of white adipocytes.ILC2s may play an important role in the effects of EA treatment,but this requires further study.

Supramolecular Radical Switches Regulated by Host-Guest Chemistry

Water-soluble thermal initiators are important radical sources to be applied in various fields.However,the uncontrolled radical generation from the high sensitivity of initiators may cause disadvantages in the applications.Here,we present a series of supramolecular radical switches regulated by the host-guest chemistry between initiators and cucurbit[8]uril(CB[8]).Thermal initiators(VA-044,VA-056,VA-057)can be spontaneously encapsulated into the cavity of CB[8]to“turn off”their radical-generation ability.Their activity will instantaneously“turn on”in the presence of other competitors such as 1-adamantylamine(ADA).Further,we demonstrated the free radical polymerization of N-isopropylacrylamide using initiators,inhibiting its activity by binding with CB[8]and initiating reaction by adding ADA.These novel supramolecular radical switches provide a facile strategy to control the generation of free radicals in a“plug-and-play”manner,which may arouse research interests in polymerization,catalysis,and the biomedical field.