Mg-Nd-Zn-Zr稀土镁合金的热变形行为

采用GLEEBLE-1500热模拟机对Mg-Nd-Zn-Zr稀土镁合金在温度为250～450.℃、应变速率为0.002～0.100.s-1、最大变形程度为60%的条件下, 进行高温压缩模拟实验研究. 分析了实验合金在高温变形时的流变应力和应变速率及变形温度之间的关系, 计算了变形激活能和应力指数, 并研究了在热压缩过程中组织的变化, 为确定该稀土镁合金的挤压温度提供了实验依据. 结果表明: 合金的峰值流变应力随应变速率的增大而增加, 随温度的升高而降低; 合金的变形激活能在300～400.℃内变化不大, 而在400～450.℃时增加很大; 根据实验分析认为该稀土镁合金挤压温度定在350～400.℃左右为宜; 在350.℃左右顺利挤出的实验合金有很好的力学性能: σb=275.5.MPa, δ=13.5%.     

铍材应力常数的X射线法测试

在X2001应力分析仪上采用悬臂梁加载法测试了可以用于铍的X射线应力测试的5个衍射晶面的应力常数。结果表明,铍的5个衍射晶面的应力常数差异较大，在进行X射线应力分析时．应采用相应衍射晶面的应力常数，才能获得准确的应力分析结果。由于X射线对铍有较大的穿透深度，必须考虑X射线穿透深度对应力常数标定的影响。     

Local Epidermal Endocrine Estrogen Protects Human Melanocytes against Oxidative Stress,a Novel Insight into Vitiligo Pathology

As the outermost barrier of the body, skin is a major target of oxidative stress. In the brain, estrogen has been reported synthesized locally and protects neurons from oxidative stress. Here, we explored whether estrogen is also locally synthesized in the skin to protect from oxidative stress and whether aberrant local estrogen synthesis is involved in skin disorders. Enzymes and estrogen receptor expression in skin cells were examined first by quantitative real-time PCR and Western blot analyses. Interestingly, the estrogen synthesis enzyme was mainly localized in epidermal keratinocytes and estrogen receptors were mainly expressed in melanocytes among 13 kinds of cultured human skin cells. The most abundant estrogen synthesis enzyme expressed in the epidermis was 17β-hydroxysteroid dehydrogenase 1 (HSD17β1) localized in keratinocytes, and the most dominant estrogen receptor expressed in the epidermis was G protein-coupled estrogen receptor 1 (GPER1) in melanocytes. To investigate whether keratinocyte-derived estradiol could protect melanocytes from oxidative stress, cultured human primary epidermal melanocytes (HEMn-MPs) were treated with H₂O₂ in the presence or absence of 17β estradiol or co-cultured with HSD17β1 siRNA-transfected keratinocytes. Keratinocyte-derived estradiol exhibited protective effects against H₂O₂-induced cell death. Further, reduced expression of HSD17β1 in the epidermis of skin from vitiligo patients was observed compared to the skin from healthy donors or in the normal portions of the skin in vitiligo patients. Our results suggest a possible new target for interventions that may be used in combination with current therapies for patients with vitiligo.     

Na+ and/or Cl− Toxicities Determine Salt Sensitivity in Soybean (Glycine max (L.) Merr.), Mungbean (Vigna radiata (L.) R. Wilczek), Cowpea (Vigna unguiculata (L.) Walp.), and Common Bean (Phaseolus vulgaris L.)

Grain legumes are important crops, but they are salt sensitive. This research dissected the responses of four (sub)tropical grain legumes to ionic components (Na⁺ and/or Cl⁻) of salt stress. Soybean, mungbean, cowpea, and common bean were subjected to NaCl, Na⁺ salts (without Cl⁻), Cl⁻ salts (without Na⁺), and a “high cation” negative control for 57 days. Growth, leaf gas exchange, and tissue ion concentrations were assessed at different growing stages. For soybean, NaCl and Na⁺ salts impaired seed dry mass (30% of control), more so than Cl⁻ salts (60% of control). All treatments impaired mungbean growth, with NaCl and Cl⁻ salt treatments affecting seed dry mass the most (2% of control). For cowpea, NaCl had the greatest adverse impact on seed dry mass (20% of control), while Na⁺ salts and Cl⁻ salts had similar intermediate effects (~45% of control). For common bean, NaCl had the greatest adverse effect on seed dry mass (4% of control), while Na⁺ salts and Cl⁻ salts impaired seed dry mass to a lesser extent (~45% of control). NaCl and Na⁺ salts (without Cl⁻) affected the photosynthesis (P_n) of soybean more than Cl⁻ salts (without Na⁺) (50% of control), while the reverse was true for mungbean. Na⁺ salts (without Cl⁻), Cl⁻ salts (without Na⁺), and NaCl had similar adverse effects on P_n of cowpea and common bean (~70% of control). In conclusion, salt sensitivity is predominantly determined by Na⁺ toxicity in soybean, Cl⁻ toxicity in mungbean, and both Na⁺ and Cl⁻ toxicity in cowpea and common bean.     

Evaluation of the Effects of Developmental Trauma on Neurotransmitter Systems Using Functional Molecular Imaging

Early life stress (ELS) is strongly associated with psychiatric disorders such as anxiety, depression, and schizophrenia in adulthood. To date, biological, behavioral, and structural aspects of ELS have been studied extensively, but their functional effects remain unclear. Here, we examined NeuroPET studies of dopaminergic, glutamatergic, and serotonergic systems in ELS animal models. Maternal separation and restraint stress were used to generate single or complex developmental trauma. Body weights of animals exposed to single trauma were similar to those of control animals; however, animals exposed to complex trauma exhibited loss of body weight when compared to controls. In behavioral tests, the complex developmental trauma group exhibited a decrease in time spent in the open arm of the elevated plus-maze and an increase in immobility time in the forced swim test when compared to control animals. In NeuroPET studies, the complex trauma group displayed a reduction in brain uptake values when compared to single trauma and control groups. Of neurotransmitter systems analyzed, the rate of decrease in brain uptake was the highest in the serotonergic group. Collectively, our results indicate that developmental trauma events induce behavioral deficits, including anxiety- and depressive-like phenotypes and dysfunction in neurotransmitter systems.     

Oxytocin Signaling as a Target to Block Social Defeat-Induced Increases in Drug Abuse Reward

There is huge scientific interest in the neuropeptide oxytocin (OXT) due to its putative capacity to modulate a wide spectrum of physiological and cognitive processes including motivation, learning, emotion, and the stress response. The present review seeks to increase the understanding of the role of OXT in an individual’s vulnerability or resilience with regard to developing a substance use disorder. It places specific attention on the role of social stress as a risk factor of addiction, and explores the hypothesis that OXT constitutes a homeostatic response to stress that buffers against its negative impact. For this purpose, the review summarizes preclinical and clinical literature regarding the effects of OXT in different stages of the addiction cycle. The current literature affirms that a well-functioning oxytocinergic system has protective effects such as the modulation of the initial response to drugs of abuse, the attenuation of the development of dependence, the blunting of drug reinstatement and a general anti-stress effect. However, this system is dysregulated if there is continuous drug use or chronic exposure to stress. In this context, OXT is emerging as a promising pharmacotherapy to restore its natural beneficial effects in the organism and to help rebalance the functions of the addicted brain.