Effect of Impact Velocity and Angle on Impact Wear Behavior of Zr-4 Alloy Cladding Tube.

In the pressurized water reactor nuclear power plant, 316L SS chips were captured by the support grid and continued to affect the Zr-4 cladding tube, causing the fuel rods to wear and perforate. In this work, a 60° acute angle cone of 316L SS was used to simulate the cyclic impact of debris on a Zr-4 alloy tube with different initial impact velocities and impact angles. Results showed that increasing the initial impact velocity will generate a wear debris accumulation layer with a wear-reducing effect, but also promote the extension and expansion of fatigue cracks, resulting in the delamination of Zr-4 alloy tubes. The inclination of the impact angle increases the energy loss. The energy loss rate of the 45° impact is as high as 69.68%, of which 78% is generated by the impact-sliding stage. The normal force is mainly responsible for the wear removal and plastic deformation of Zr-4 alloy tubes. Tangential forces cause severe cutting in Zr-4 alloys and pushes the resulting wear debris away from the contact surfaces.

[Foliar stable carbon isotope composition and water use efficiency of plant in the Karst seasonal rain forest.] / å–€æ–¯ç‰¹å­£èŠ‚æ€§é›¨æž—æ¤ç‰©å¶ç‰‡ç¢³åŒä½ç´ ç»„æˆåŠæ°´åˆ†åˆ©ç”¨æ•ˆçŽ‡.

To enrich niche partition and species coexistence theory in karst seasonal rain forest, and provide reference for species selection and configuration for rocky desertification control, we exami-ned foliar stable carbon isotope composition (δ13C) and water use efficiency (WUE) of the representative species in different habitats and the same tree species in different habitats. The results showed that foliar δ13C value in karst seasonal rain forest ranged from -34.13‰ to -29.69‰, with a mean value of (-31.40±1.19)‰. WUE ranged from 9.08-58.76 µmol·mol-1, with a mean value of 41.79 µmol·mol-1. Both of them were lower than subtropical and warm temperate forests at higher latitude, but higher than tropical rain forests at lower latitude and non-karst seasonal rain forests at the same latitude. The foliar δ13C value and WUE of representative species gradually increased with the increases of drought index from the depression to the top of the mountain. The foliar δ13C value and WUE of the same tree species increased with altitude. These results indicated that water use efficiency of tree species was not only related to climate factors, but also related to the geological background and water availability of the habitat. The water use efficiency of plants in karst area was higher than that in non-karst area, and was higher in dry habitat than in wet habitat under the same climatic condition. It showed that having different water use efficiencies was one of the strategies for plants in karst area to adapt to different habitats and maintain species coexistence.

[Analysis of Heavy Metal Pollution and Ecological Risk Assessment on Vegetation Leaves in Baoji City].

Using seven types of vegetation and seven heavy metals (Cr, Cu, Ni, Mn, Pb, Cd, and As), the present study explored the ability of accumulation and degree of contamination in the leaves of vegetation in Binhe Road. The results demonstrated a negative trend between vegetation height and heavy metal content of vegetation leaves, i.e., as plant height increased, heavy metal contamination decreased. Leaves varied in the accumulation of heavy metals depending on the heavy metal and vegetation type. Cr, Mn, and Pb content were the most abundant in vegetation leaves. The highest values for Cr, Cu, Ni, and Mn were observed in the vegetative leaves of Hybrida vicary privet and were 217.33, 58.61, 36.79, 1676.14 mg·kg-1, respectively. The highest Pb content was 1295.64 mg·kg-1 in Ligustrun lucidum, the highest Cd content was 110.19 mg·kg-1 in Cedrus deodara, and the highest As content was 139.42 mg·kg-1in Prunus cerasifera. The degree of pollution in vegetation leaves was evaluated using the comprehensive index method Single-factor pollution index method and the Nemero Composite Index Method. The Single-factor pollution index of vegetation leaves with Prunus cerasifera, Platanus acerifolia, Cercis chinensis were between 0.02-1.23, and the Nemero Composite Index values were 1.01, 0.82, 0.4, respectively, with light pollution. The Single-factor pollution index of vegetation leaves by Cedrus deodara, Platycladus orientalis, Hybrida vicary privet and Ligustrun lucidum were much higher than 1, and the Nemero Composite Index was 16.53, 140.64, 98.80, and 37.52, respectively, with high levels of pollution. The potential ecological risk of heavy metals in vegetation leaves was determined using the Hakanson potential ecological risk assessment method. The order of the average potential ecological risk degree of the seven examined heavy metals was as follows:Cd > Ni > Cr > As > Pb > Cu > Mn, and the RI value range was 19.04-4020.29, with high levels of pollution.

Scientific experiment exploration course of biomedical engineering specialty / 医疗卫生装备

Objective To study the teaching innovation of the scientific experiment exploration course in biomedical engineering specialty based on its characteristics involving in animal physiological parameters acquisition, circuit system design, signal processing and etc. Methods The course aimed to guide the student in observation learning, practice and inquiry with considerations on course significance,basic principles for designing the course,implementation scheme of course teaching, suggestions for course improvement, instances of practical teaching and etc. Results Four basic principles were proposed for course teaching. An implementation scheme was determined with emphases on teaching materials, theory, practice, discussion and exploration. The course had the rule being inquiry, and some suggestions were put forward about student feedback, scientific research progress, experiment platform renewal and etc. Conclusion Teaching practice proves that the improved course contributes to enhancing the student's understanding of experiment exploration of biomedical engineering specialty and to promoting multi-discipline fusion and cross-over personnel training, and thus is of great reference for other universities.

Nicotinic Acetylcholine Receptors Mediate the Suppressive Effect of an Injection of Diluted Bee Venom into the GV3 Acupoint on Oxaliplatin-Induced Neuropathic Cold Allodynia in Rats.

Oxaliplatin, a platinum-based chemotherapy drug, often induces acute neuropathic pain, especially cold allodynia, even after a single administration. Subcutaneous injection of diluted bee venom (BV) into acupoints has been used to treat various pain symptoms in traditional oriental medicine. Although we previously demonstrated the suppressive effect of BV injection on oxaliplatin-induced cold allodynia in rats, its neurochemical mechanism remained unclear. This study investigates whether and how the cholinergic system mediates the relieving effect of BV injection on cold allodynia in oxaliplatin-administered rats. The behavioral signs of cold allodynia induced by an oxaliplatin administration (6 mg/kg, intraperitoneally (i.p.)) were evaluated by a tail immersion test in cold water (4°C). BV (0.25 mg/kg, subcutaneously (s.c.)) injection into the Yaoyangguan acupoint, located between the spinous processes of the fourth and fifth lumbar vertebrae, significantly alleviated the cold allodynia. This relieving effect of BV injection on oxaliplatin-induced cold allodynia was blocked by a pretreatment with mecamylamine (a non-selective nicotinic receptor antagonist, 2 mg/kg, i.p.), but not by atropine (a non-selective muscarinic receptor antagonist, 1 mg/kg, i.p.). Further, dihydro-ß-erythroidinehydrobromide (DHßE, an α4ß2 nicotinic antagonist, 5 mg/kg, i.p.) prevented the anti-allodynic effect of BV, whereas methyllycaconitine (an α7 nicotinic antagonist, 6 mg/kg, i.p.) did not. Finally, intrathecal administration of DHßE (10 nM) blocked the BV-induced anti-allodynic effect. These results suggest that nicotinic acetylcholine receptors, especially spinal α4ß2 receptors, but not muscarinic receptors, mediate the suppressive effect of BV injection on oxaliplatin-induced acute cold allodynia in rats.

Serotonergic mechanism of the relieving effect of bee venom acupuncture on oxaliplatin-induced neuropathic cold allodynia in rats.

BACKGROUND: Oxaliplatin, an important chemotherapy drug for advanced colorectal cancer, often induces peripheral neuropathy, especially cold allodynia. Our previous study showed that bee venom acupuncture (BVA), which has been traditionally used in Korea to treat various pain symptoms, potently relieves oxaliplatin-induced cold allodynia in rats. However, the mechanism for this anti-allodynic effect of BVA remains poorly understood. We investigated whether and how the central serotonergic system, a well-known pathway for acupuncture analgesia, mediates the relieving effect of BVA on cold allodynia in oxaliplatin-injected rats. METHODS: The behavioral signs of cold allodynia in Sprague-Dawley (SD) rats were induced by a single injection of oxaliplatin (6 mg/kg, i.p.). Before and after BVA treatment, the cold allodynia signs were evaluated by immersing the rat's tail into cold water (4°C) and measuring the withdrawal latency. For BVA treatment, a diluted BV (0.25 mg/kg) was subcutaneously administered into Yaoyangguan (GV3) acupoint, which is located between the spinous processes of the fourth and the fifth lumbar vertebra. Serotonin was depleted by a daily injection of DL-p-chlorophenylalanine (PCPA, 150 mg/kg, i.p.) for 3 days. The amount of serotonin in the spinal cord was measured by ELISA. Serotonergic receptor antagonists were administered intraperitoneally or intrathecally before BVA treatment. RESULTS: The serotonin levels in the spinal cord were significantly increased by BVA treatment and such increase was significantly reduced by PCPA. This PCPA pretreatment abolished the relieving effect of BVA on oxaliplatin-induced cold allodynia. Either of methysergide (mixed 5-HT1/5-HT2 receptor antagonist, 1 mg/kg, i.p.) or MDL-72222 (5-HT3 receptor antagonist, 1 mg/kg, i.p) blocked the anti-allodynic effect of BVA. Further, an intrathecal injection of MDL-72222 (12 µg) completely blocked the BVA-induced anti-allodynic action, whereas NAN-190 (5-HT1A receptor antagonist, 15 µg, i.t.) or ketanserin (5-HT2A receptor antagonist, 30 µg, i.t.) did not. CONCLUSIONS: These results suggest that BVA treatment alleviates oxaliplatin-induced acute cold allodynia in rats via activation of the serotonergic system, especially spinal 5-HT3 receptors. Thus, our findings may provide a clinically useful evidence for the application of BVA as an alternative therapeutic option for the management of peripheral neuropathy, a dose-limiting side effect that occurs after an administration of oxaliplatin.

Effect of bee venom acupuncture on oxaliplatin-induced cold allodynia in rats.

Oxaliplatin, a chemotherapy drug, often leads to neuropathic cold allodynia after a single administration. Bee venom acupuncture (BVA) has been used in Korea to relieve various pain symptoms and is shown to have a potent antiallodynic effect in nerve-injured rats. We examined whether BVA relieves oxaliplatin-induced cold allodynia and which endogenous analgesic system is implicated. The cold allodynia induced by an oxaliplatin injection (6 mg/kg, i.p.) was evaluated by immersing the rat's tail into cold water (4°C) and measuring the withdrawal latency. BVA (1.0 mg/kg, s.c.) at Yaoyangguan (GV3), Quchi (LI11), or Zusanli (ST36) acupoints significantly reduced cold allodynia with the longest effect being shown in the GV3 group. Conversely, a high dose of BVA (2.5 mg/kg) at GV3 did not show a significant antiallodynic effect. Phentolamine ( α -adrenergic antagonist, 2 mg/kg, i.p.) partially blocked the relieving effect of BVA on allodynia, whereas naloxone (opioid antagonist, 2 mg/kg, i.p.) did not. We further confirmed that an intrathecal administration of idazoxan ( α 2-adrenergic antagonist, 50 µ g) blocked the BVA-induced anti-allodynic effect. These results indicate that BVA alleviates oxaliplatin-induced cold allodynia in rats, at least partly, through activation of the noradrenergic system. Thus, BVA might be a potential therapeutic option in oxaliplatin-induced neuropathy.