Simultaneously Regulating Electrochemical Corrosion Behavior and Wettability of Magnesium-Neodymium Alloy by Self-Layered Chemical Conversion Coating.

Rapid corrosion in aqueous solutions of magnesium alloys is one of the major obstacles to their wide application, and coating plays a crucial role in their corrosion protection. Recently, protection- and function-integrated coatings have attracted much attention in the research field of magnesium alloys. In this work, a simple chemical conversion process is proposed to fabricate a composite coating on a magnesium-neodymium alloy through immersion in an aqueous solution made of Ca(OH)2 and NaHCO3. After the immersion process, a coating consisting of two spontaneously formed layers is acquired. The top flower-like layer is composed of Mg5(OH)2(CO3)4∙4H2O, Mg(OH)2 and CaCO3, and the inner dense layer is speculated to be Mg(OH)2. Electrochemical impedance spectroscopy, polarization tests, and hydrogen evolution are combined to evaluate the corrosion resistance in simulated body fluid, simulated seawater solution, and simulated concrete pore solution, which reveals that the coated sample has better corrosion resistance than the uncoated one. After the coated sample is modified with fluorinated silane, a water-repellent surface can be achieved with an average water contact angle of 151.74° and a sliding angle of about 4°. Therefore, our results indicate that effective corrosion protection and potential self-cleaning ability have been integrated on the surface of the magnesium alloy in this study. In addition, the formation mechanism of the self-layered coating is discussed from the viewpoint of the interaction between the substrate and its external solution.

Effects of moxibustion at "Zusanli" (ST 36) on oxidative stress and intestinal flora in aging rats. / 艾灸"足三里"å¯¹è¡°è€å¤§é¼ æ°§åŒ–åº”æ¿€å’Œè‚ é“èŒç¾¤çš„å½±å“.

OBJECTIVES: To observe the effects of moxibustion at "Zusanli"(ST 36)on oxidative stress and intestinal flora in subacute aging rats, and to explore the possible mechanism of moxibustion in delaying aging. METHODS: Thirty SD rats were randomly divided into a blank group, a model group and a Zusanli group, with 10 rats in each group. Subacute aging model was established by intraperitoneal injection of D-galactose at dosage of 500 mg/kg in the model group and the Zusanli group, once a day for 42 days. In the Zusanli group, moxibustion was applied at bilateral "Zusanli" (ST 36) , once a day, 3 moxa cones at each acupoint, for consecutive 28 days. After intervention, the serum levels of superoxide dismutase (SOD) and malondialdehyde (MDA) were detected by ELISA; the intestinal flora was detected by 16S rRNA sequencing technique in each group. RESULTS: Compared with the blank group, the serum level of SOD was decreased (P<0.01), the serum level of MDA was increased (P<0.01) in the model group. Compared with the model group, the serum level of SOD was increased (P<0.01), the serum level of MDA was decreased (P<0.01) in the Zusanli group. Compared with the blank group, Chao1 and Shannon indexes were decreased in the model group (P<0.01, P<0.05). Compared with the model group, Chao1 and Shannon indexes were increased in the Zusanli group (P<0.01, P<0.05). Compared with the blank group, the relative abundance of Firmicutes, Treponema_2 and Lachnospiraceae_NK4A136_group was increased (P<0.05, P<0.01), while the relative abundance of Prevotellaceae_UCG-003 and the relative abundance ratio of Bacteroidetes and Firmicutes (B/F value) were decreased (P<0.01, P<0.05) in the model group. Compared with the model group, the relative abundance of Firmicutes and Treponema_2 was decreased (P<0.01), while the relative abundance of Bacteroidetes, Lactobacillus, Prevotellaceae_UCG-003 and B/F value were increased (P<0.05, P<0.01) in the Zusanli group. CONCLUSIONS: Moxibustion at "Zusanli"(ST 36)can effectively improve the level of oxidative stress, regulate the constitution of intestinal flora, maintain the microecological balance of intestinal flora in aging rats, and thus play a role in delaying aging.

[Effects of moxibustion on acupoints at "opening" time on testicular tissue apoptosis in aging rats].

OBJECTIVE: To observe the effect of "lingguibafa" moxibustion at "opening" time on the level of superoxide dismutase(SOD), malondialdehyde(MDA), the protein expressions of B-cell lymphoma-2 (Bcl-2) and Bcl-2 associated X protein (Bax) in aging model rats. METHODS: SD rats were randomly divided into blank control, model and lingguibafa groups, with 8 rats in each group. The aging model was established by daily intraperitoneal injection of D-galactose (500 mg/kg) for 42 consecutive days. After successful modeling, moxibustion intervention was applied at"lingguibafa" acupoints, 3 moxa-cone for each acupoint, once a day for 28 consecutive days. The contents of SOD and MDA in serum were detected by ELISA. Morphological changes of testicular tissue and the number of Leydig cells were observed after HE staining. Apoptosis rate of testicular cells was detected by TUNEL staining. The protein expression levels of Bcl-2 and Bax in testis were detected by Western blot. RESULTS: Compared with the blank control group, the SOD content in the serum, the number of testicular Leydig cells, the expression level of Bcl-2 protein in testis were significantly decreased (P<0.01) in the model group, while the MDA content in the serum, the apoptosis rate of testicular cells and the expression level of Bax protein in testis were significantly increased (P<0.01). Compared with the model group, the SOD content in serum, the number of testicular Leydig cells, the Bcl-2 protein expression in testis were significantly increased (P<0.01), while the MDA content in serum, the apoptosis rate of testicular cells, the expression level of Bax protein in testis were significantly decreased(P<0.01) in the lingguibafa group. CONCLUSION: Moxibustion on acupoints at "opening" time can delay testicular aging, and the mechanism may be related to balancing the metabolism of free radicals, reducing oxidative damage, and inhibiting the apoptosis of testicular cells.