Effects on Zinc Stress on Stress-Resistance Physiological and Biochemical Indexes of Jatropha curcas seedlings

Jatropha curcas seedlings were cultured for 21 d under 6 zinc concentrations of 0,25,50,100,200,400 mg/l to study the effects of ZnS O4 stress on the mechanism of resistance to heavy metal stress of J. curcas seedlings. The results showed that with the increase of stress concentration,the content of chlorophyll-a decreased and the activity of POD first increased and then maintained at a certain level or decreased slowly. The contents of soluble sugar,malondialdehyde,soluble protein and free proline increased,and the root activity increased first and then decreased. The relative conductivity of J. curcas seedlings decreased first and then increased,which indicated that the leaves of J. curcas seedlings had some adaptability and self-repairing capability under zinc toxicity stress,but the adaptability and self-repair ability were limited.

Effects of Selenium and Zinc on Renal Oxidative Stress and Apoptosis Induced by Fluoride in Rats

Objective To study the effects of selenium and zinc on oxidative stress, apoptosis, and cell cycle changes in rat renal cells induced by fluoride. Methods Wistar rats were given distilled water containing sodium fluoride （50 mg/L NaF） and were gavaged with different doses of selenium-zinc preparation for six months. Four groups were used and each group had eight animals （four males and four females）. Group one, sham-handled control; group two, 50 mg/L NaF; group three, 50 mg/L NaF with a low dose of selenium-zinc preparation （0.1 mg/kg Na2 SeO3 and 14.8 mg/kg ZnSO4 · 7H2O）; and group four, 50 mg/L NaF with a high dose of selenium-zinc preparation （0.2 mg/kg Na2 SeO3 and29.6 mg/kg ZnSO4 · 7H20）. The activities of serum glutathione peroxidase （GSH-Px）, kidney superoxide dismutase （SOD）, and the levels of malondialdehyde （MDA） and glutathione （GSH） in the kidney were measured to assess the oxidative stress. Kidney cell apoptosis and cell cycle were detected by flow cytometry. Results NaF at the dose of 50 mg/L increased excretion of fluoride in urine, promoted activity of urine γ -glutarnyl transpeptidase （ γ -GT）, inhibited activity of serum GSH-PX and kidney SOD, reduce kidney GSH content, and increased kidney MDA. NaF at the dose of 50 mg/L also induced rat renal apoptosls, reduced the cell number of G2/M phase in cell cycle, and decreased DNA relative content significantly. Selenium and zinc inhibited effects of NaF on oxidative stress and apoptosis, promoted the cell number of G2/M phase in cell cycle, but failed to increase relative DNA content significantly. Conclusion Sodium fluoride administered at the dose of 50 mg/L for six months induced oxidative stress and apoptosis, and changes the cell cycle in rat renal cells. Selenium and zinc antagonize oxidative stress, apoptosis, and cell cycle changes induced by excess fluoride.

Role of zinc as an antioxidant and anti-inflammatory to relieve cadmium oxidative stress induced testicular damage in rats

Objective:To investigate the role of zinc in reducing the deleterious effects of cadmium on male gonads.Methods:Rats were injected subcutaneously with CdCl_2 and ZnCl_2 at dose level of2.2 mg/kg(1/40 of LD50 of cadmium per day).Results:The rats treated with cadmium exhibited a significant increase in levels of testicular malondialdehyde,tumor necrosis factor-alpha,nitrogen oxide and inducible nitrogen oxide synthase immunostaining reaction,as well as an elevation of blood hydroperoxide and follicle stimulating hormone.In addition,a significant decrease in testicular ascorbic acid,zinc,reduced glutathione,catalase,superoxide dismutase,sex organ weight,plasma testosterone and luteinizing hormone were observed in the cadmium group.Sperm motility and count were decreased with cadmium treatment,while sperm abnormalities elevated significantly.Zinc treatment was found to mitigate the toxic effects of cadmium on oxidative stress,spermatogenesis,sex hormones,and inflammatory markers.Rats injected with cadmium showed intense histopathological changes.Zinc manifested protective role and markedly reduced tissues damage induced by cadmium.Conclusions:The protective effect of zinc can be attributed to its antioxidant and antiinflammatory properties.

Temperature-dependent bias-stress-induced electrical instability of amorphous indium-gallium-zinc-oxide thin-film transistors

The time and temperature dependence of threshold voltage shift under positive-bias stress（PBS） and the following recovery process are investigated in amorphous indium-gallium-zinc-oxide（a-IGZO） thin-film transistors. It is found that the time dependence of threshold voltage shift can be well described by a stretched exponential equation in which the time constant τ is found to be temperature dependent. Based on Arrhenius plots, an average effective energy barrier Eτ stress= 0.72 eV for the PBS process and an average effective energy barrier Eτ recovery= 0.58 eV for the recovery process are extracted respectively. A charge trapping/detrapping model is used to explain the threshold voltage shift in both the PBS and the recovery process. The influence of gate bias stress on transistor performance is one of the most critical issues for practical device development.

Positive and Negative Environmental Effect of Using Zinc Oxide Nanoparticles on Wheat under Drought Stress

Nanoscience is a development concept in the field of agriculture. Water scarcity is one of the most serious stresses that restrict growth of plant. This search was done to value the positive and negative influence of ZnO nanoparticles on wheat plant growth under drought stress. A green synthesis technique was used to produce pollutant-free nano structures. A field experiment was carried out during successive season (2019/2020). NP-Zn-O was applied either by seed-soaking, foliar spraying, or both together applications. The dose of ZnO NPs was 100 mg/l. Data showed that drought stress reduced the grain and shoot wheat yield. The use of different forms of ZnO improved the grain and shoot wheat yield, these increases reached 1.16-, 1.54-fold that control. In addition, one of the other effects of Zn-O-NPs is to increase the levels of chlorophyll and proline antioxidants in plant tissues, as it is a cofactor for enzymes such as superoxide dismutase and catalase. The data suggest that the role of ZnO NPs is not only to improve plant growth and physiological parameters, but also to improve nutrient uptake and plant nutrient levels. In this regard, the use of zinc in the form of ZnO NPs has a positive effect on reducing the adverse effects of drought conditions and improving the nutritional quality of plants.

滇杨幼苗对镉、锌胁迫的生理响应与耐受性研究

为探究滇杨幼苗在Cd、Zn单一及复合胁迫下的生长、生理响应与耐受特征,采用土培盆栽的方式开展研究。结果表明:Cd、Zn单一及复合胁迫未显著改变滇杨株高、地径和总生物量,但单一Zn胁迫显著提高总根长、根表面积和根体积,Cd-Zn胁迫显著降低总根长;Zn可改善滇杨的苗木生长质量,Cd可导致滇杨生长变差,而Cd-Zn复合胁迫时生长状况最差。Cd、Zn单一胁迫未显著改变滇杨叶片的光合色素含量和净光合速率,Cd-Zn复合胁迫时叶绿素含量显著降低,但净光合速率和光响应特征参数变化不显著,而Cd单一胁迫时滇杨的R_(d)和LCP较CK显著增高,Zn单一胁迫时则LSP显著增高。Cd和Cd-Zn胁迫可激发滇杨氧化应激防御系统,使SOD和CAT活性显著提高,MDA和TPh含量无显著变化,Zn胁迫时SOD、CAT、MDA和TPh含量均无显著变化。滇杨幼苗对Cd、Zn单一及复合胁迫表现出耐受性,可作为Cd、Zn污染土壤生态修复的重要候选树种,其综合耐受值为Zn>CK>Cd>Cd-Zn。

Improvement in the electrical performance and bias-stress stability of dual-active-layered silicon zinc oxide/zinc oxide thin-film transistor

Si-doped zinc oxide（SZO） thin films are deposited by using a co-sputtering method,and used as the channel active layers of ZnO-based TFTs with single and dual active layer structures.The effects of silicon content on the optical transmittance of the SZO thin film and electrical properties of the SZO TFT are investigated.Moreover,the electrical performances and bias-stress stabilities of the single- and dual-active-layer TFTs are investigated and compared to reveal the effects of the Si doping and dual-active-layer structure.The average transmittances of all the SZO films are about 90% in the visible light region of 400 nm-800 nm,and the optical band gap of the SZO film gradually increases with increasing Si content.The Si-doping can effectively suppress the grain growth of ZnO,revealed by atomic force microscope analysis.Compared with that of the undoped ZnO TFT,the off-state current of the SZO TFT is reduced by more than two orders of magnitude and it is 1.5 × 10^-12 A,and thus the on/off current ratio is increased by more than two orders of magnitude.In summary,the SZO/ZnO TFT with dual-active-layer structure exhibits a high on/off current ratio of 4.0 × 10^6 and superior stability under gate-bias and drain-bias stress.

硫酸锌胁迫对萌发青稞功能成分及抗氧化能力的影响

该研究以藏青2000为原料,采用酶联免疫吸附法等方法测定了不同浓度硫酸锌胁迫下萌发青稞的功能成分含量及抗氧化能力,同时记录其萌发率等指标。结果表明,硫酸锌胁迫对青稞的萌发率、水分含量、根长和芽长有抑制作用。随着时间的延长,在不同浓度硫酸锌胁迫下,褪黑素、γ-氨基丁酸含量先增加后降低;还原糖、可溶性含量先上升后达到动态平衡;β-葡聚糖、总黄酮及总酚含量先降低后升高。其中,0.6 mmol/L硫酸锌胁迫萌发第7天时总酚含量是对照组的1.12倍;0.8 mmol/L硫酸锌胁迫萌发第6天时褪黑素与γ-氨基丁酸含量分别是对照组的1.35、1.40倍,第7天时总黄酮含量是对照组1.28倍。抗氧化能力结果显示,萌发青稞的抗氧化能力与其含有的总黄酮总酚含量显著正相关(P<0.01)。综上,萌发可改善青稞品质,0.6~0.8 mmol/L的硫酸锌胁迫可有效提高萌发青稞功能成分含量及抗氧化能力。

铜锌复合胁迫下禾本科观赏草的富集、转运效应评价

研究禾本科观赏草在土壤重金属铜、锌复合污染下的富集、转运效应,筛选出耐性品种,为挖掘超富集植物及推动利用植物修复铜、锌污染环境提供参考依据。以9种常见禾本科观赏草作为试验植材,设置5个胁迫梯度,采用盆栽控制法,探究供试观赏草体内铜、锌含量分布状况并分析其对铜、锌的富集能力与转运特征。结果表明,不同供试观赏草吸收重金属铜、锌的能力存在差异;不同部位吸收重金属铜、锌的能力亦差异显著,供试观赏草地上部吸收锌的能力强于地下部,而地下部吸收铜的能力强于地上部。供试观赏草富集、转移锌的能力均强于铜,在锌富集系数、转运系数方面高于铜。采用隶属函数法及Q型聚类分析法,当相对距离为7.5时,可将供试观赏草划分为高、中、低铜锌积累型3类,丽色画眉草、细叶芒综合表现最强且属于高铜锌积累型。

基于转录组测序技术研究黑水虻幼虫对锌离子胁迫的响应

黑水虻Hermetia illucens L.是世界范围内重要资源昆虫,过量锌离子(Zn^(2+))胁迫会对其幼虫的生长发育产生影响,而转录组分析有助于揭示Zn^(2+)胁迫影响黑水虻幼虫发育的分子机制。本试验以不同浓度Zn^(2+)(75、150、300、1200 mg/kg)对黑水虻幼虫进行连续5代胁迫,利用Illumina HiSeq 4000高通量测序平台对第5代6龄幼虫转录组进行测序及分析。结果显示,Zn^(2+)胁迫影响了第5代黑水虻幼虫的基因表达水平,75、150、300和1200 mg/kg Zn^(2+)处理幼虫中上调/下调的差异表达基因分别是1293/1839、1277/2306、1080/1966和1444/2170个;GO富集分析结果表明,差异表达基因在细胞过程中所占比例最大,细胞组分中主要是细胞和细胞成分,分子功能中主要为催化活性和细胞结合;KEGG富集差异分析显示,75 mg/kg Zn^(2+)胁迫下差异表达基因主要富集在免疫相关反应、免疫相关信号传导途径及脂类物质代谢,300 mg/kg Zn^(2+)处理组差异表达基因主要富集在氨基酸代谢和碳水化合物代谢;1200 mg/kg Zn^(2+)胁迫下氨基酸和脂类代谢、免疫相关反应和生长均受到严重影响,这些富集的与上述有关的差异基因大多表达下调。本研究表明,Zn^(2+)胁迫影响了黑水虻幼虫基因表达,高浓度Zn^(2+)胁迫基因表达影响尤为显著,主要表现在细胞过程、催化活性和结合的基因表达下调;高浓度Zn^(2+)胁迫还导致了黑水虻幼虫免疫系统、环境相关信号传导途径和脂质代谢等的紊乱。

饲粮锌对高温应激雪山草鸡生长性能、营养物质表观消化率和血清生化指标的影响

【目的】评估不同形态和剂量的锌对高温应激环境中雪山草鸡生长性能、表观消化率和血清生化指标的影响,以期为高温环境下雪山草鸡的锌营养提供参考。【方法】试验采用2(锌源)×2(锌添加水平)两因子完全随机设计,2种锌源分别为无机硫酸锌和中等螯合强度蛋白锌,2种锌添加水平分别为30和60 mg/kg,共4个试验组;另设1个满足肉鸡锌需要量的对照组。选取320只61日龄雪山草鸡,随机分配到5个组中,每个处理8个重复,每个重复8只鸡。预试期7 d,正试期28 d,均在高温应激条件下进行。分别在试验第14(75日龄)和28(89日龄)天时采集饲料样、粪样和血样,用于测定肉鸡的生长性能、养分表观消化率和血清生化指标。【结果】①锌源、锌添加水平及两因子互作对高温应激肉鸡的生长性能均无显著影响(P>0.05)。②与对照组相比,饲粮中添加锌显著提高了肉鸡粗蛋白质和粗脂肪的表观消化率(P<0.05)。锌源对干物质的消化率有显著影响,在锌源主效应上,与饲粮中添加无机硫酸锌相比,添加中等螯合强度蛋白锌显著降低了高温应激肉鸡的干物质表观消化率(P<0.05)。③与对照组相比,饲粮中添加锌显著提高了试验第14天时肉鸡血清中总蛋白、白蛋白和球蛋白含量(P<0.05),以及显著提高了试验第28天时肉鸡血清中总蛋白和白蛋白含量(P<0.05)。锌源对试验第14天时肉鸡血清中总蛋白和白蛋白含量有显著影响(P<0.05);锌水平对试验第14天时肉鸡血清中总蛋白、白蛋白和球蛋白含量,以及试验第28天时肉鸡血清中总蛋白和白蛋白含量有显著影响(P<0.05);锌源×锌水平交互对试验第14天时肉鸡血清中总蛋白含量和试验第28天时肉鸡血清中白蛋白含量均有显著影响(P<0.05),其中饲粮中添加60 mg/kg中等螯合强度蛋白锌作用效果最佳。④在锌源、锌水平和锌源×锌水平互作效应上,饲粮中添加锌对高温应激肉鸡血清中谷丙转氨酶和谷草转氨酶活性均无显著影响(P>0.05)。⑤与对照组相比,饲粮中添加锌显著提高了试验第14天时肉鸡血清中总胆固醇和高密度胆固醇含量,显著降低了试验第28天时肉鸡血清中总胆固醇和低密度胆固醇含量(P<0.05)。锌水平对肉鸡血清中总胆固醇、高密度胆固醇和低密度胆固醇含量均有显著影响(P<0.05)。【结论】在高温应激条件下,饲粮中添加锌虽然没有显著改善肉鸡的生长性能,但对肉鸡粗蛋白质和粗脂肪的表观消化率产生了显著影响,并对高温应激肉鸡血清蛋白质和脂代谢指标产生有益影响,有助于维持肉鸡生理功能的稳定性。

黄芪甲苷通过GATA4途径调控内质网应激对激素性股骨头缺血坏死大鼠的作用机制

目的探讨黄芪甲苷(As-Ⅳ)通过锌指转录因子(GATA4)途径调控内质网应激对激素性股骨头缺血坏死(SANFH)大鼠的影响及其作用机制。方法58只SD大鼠,随机选取10只作为对照组(皮下注射生理盐水,1周7次,连续4周),其余48只大鼠复制SANFH模型,8只未建模成功,40只大鼠建模成功后,随机分为模型组、GATA 4干扰组、As-Ⅳ组、As-Ⅳ+GATA 4干扰组,每组10只。造模4周开始As-Ⅳ组、As-Ⅳ+GATA 4干扰组分别灌胃40 mg/kg的As-Ⅳ,余灌胃等量生理盐水,1次/d,共20 d;GATA4干扰组、As-Ⅳ+GATA4干扰组于造模第1周开始尾静脉注射GATA4干扰载体,1次/周,共4次。比较各组股骨Micro-CT扫描参数、病理学变化、血清氧化应激水平及股骨头组织中GATA4、丙酮酸激酶M2型(PKM2)及骨代谢相关核因子κB受体激活因子(RANK)、RANK配体(RANKL)及内质网应激相关蛋白CAAT增强子结合蛋白同源蛋白(CHOP)、葡萄糖调节蛋白78(GRP78)、半胱氨酸蛋白水解酶12(Caspase-12)蛋白表达情况。结果与GATA 4干扰组比较,As-Ⅳ+GATA 4干扰组、As-Ⅳ组的骨小梁数量、骨小梁厚度、骨体积分数依次升高,骨小梁分离度依次降低(P<0.05)。HE染色显示,模型组大鼠股骨头出现严重坏死,GATA 4干扰组股骨头病变情况加重,As-Ⅳ+GATA 4干扰组、As-Ⅳ组大鼠股骨头坏死情况减轻。与GATA 4干扰组比较,As-Ⅳ+GATA 4干扰组、As-Ⅳ组血清超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH)水平、GATA 4、PKM2蛋白相对表达量依次升高,血清丙二醛(MDA)水平、RANKL、RANK、CHOP、GRP78、Caspase-12蛋白相对表达量依次降低(P<0.05)。结论As-Ⅳ有助于缓解SANFH大鼠股骨头坏死进展,其机制可能与激活GATA 4/PKM2通路抑制内质网应激有关。

喷施锌、钾、锰对镉胁迫下小麦生长的影响

为了缓解镉毒害,促进小麦生长,采用盆栽试验方式,研究了叶面喷施锌、钾、锰元素对镉胁迫下小麦生长的影响。结果表明:与空白对照相比,叶面喷施锌、钾、锰元素可使小麦株高分别提高10.6%、4.9%、8.0%,产量分别提高18.6%、12.1%、15.8%,千粒重分别提高8.0%、6.0%、6.6%,籽粒镉含量分别降低20.0%、18.0%、18.6%。说明叶面喷施一定浓度的锌、钾、锰元素,能够促进小麦生长,降低重金属镉的含量,提升小麦品质。

基于microRNA-21响应的Zn^(2+)/DNA自组装体用于肿瘤的检测和氧化应激治疗

DNA材料具有的特异性、可编程性和生物相容性,使得其在生物检测和药物递送方面具有很大的应用优势。为了进一步拓展DNA材料的应用和合成方法,本文报道了利用DNA与金属离子之间的配合作用,简单高效地制备具有肿瘤标志物micro RNA-21(mi R-21)响应性的Zn^(2+)/DNA自组装纳米粒子(ZDNPs)。通过粒子中DNA发卡结构与mi R-21的特异性互补,激活荧光信号并释放Zn^(2+),导致细胞内产生大量活性氧,从而用于肿瘤的荧光成像和氧化应激治疗。合成的ZDNPs为形状均匀的球形粒子,能有效对Zn^(2+)进行装载。通过ZDNPs对mi R-21的响应性实验,验证了ZDNPs与miR-21浓度之间具有良好的线性响应荧光信号,线性响应范围在5~160 nmol/L,检测限为5 nmol/L,且具备特异性。此外,本文对ZDNPs在细胞内的作用效果也进行了研究,结果表明其能在肿瘤细胞内进行响应性的荧光成像,并能通过氧化应激途径介导肿瘤细胞凋亡。在活体的荧光成像和肿瘤治疗中,ZDNPs在肿瘤病灶部位体现出特异性和持续性的示踪能力,并且对肿瘤产生了明显的生长抑制效果。

基于Nrf-2/HO-1探究甘草锌对黄褐斑小鼠的治疗作用

目的探讨甘草锌对黄褐斑的治疗作用。方法将36只BALB/c小鼠平均分为空白组、模型组、甘草锌低剂量组、甘草锌中剂量组、甘草锌高剂量组和氨甲环酸组,用100 mJ/cm^(2) UVB照射联合15 mg/kg黄体酮注射进行黄褐斑造模,后对小鼠进行氨甲环酸(0.065 g/kg)与甘草锌低(0.65 g/kg)/中(1.3 g/kg)/高(2.6 g/kg)剂量连续治疗14 d。取皮肤进行HE、Masson-Fontana染色;并检测皮肤和外周血中SOD、MDA、GSP-Px、TNF-α、IL-1β及IL-6含量;皮肤组织中浆蛋白Nrf-2、核蛋白Nrf-2、HO-1表达水平。结果与模型组相比较,高剂量甘草锌组黑色素细胞形成、胶原细胞坏死与炎性浸润减少(P<0.01),MDA、IL-6、IL-1β与TNF-α表达和浆蛋白Nrf-2表达降低(P<0.01),GSP-Px、SOD表达和核蛋白Nrf-2、HO-1表达增加(P<0.01)。结论甘草锌激活Nrf-2/HO-1通路启动HO-1、SOD和GSP-Px高表达抗氧化应激,从而减少黑色素形成。

基于FLAC^(3D)对某铅锌矿巷道稳定性及采空区治理方案研究

根据Hoek-Brown准则,采用Roclab1.0软件对岩石力学实验参数数据计算,获取矿体和围岩的岩石力学参数,在此基础上运用FLAC^(3D)数值模拟铅锌矿山矿体回采后,采空区围岩及巷道最大主应力、竖向位移、塑性区的变化情况,判定铅锌矿体回采对现有巷道的影响,最终为现场采空区治理提供相应的理论依据。

水泥固化锌污染黄土力学特性试验研究

聚焦于重金属污染黄土而劣化的实际工程问题,探究水泥固化重金属污染黄土的强度、应力-应变特性,以水泥固化锌离子污染黄土为研究对象,考虑水泥掺量和养护龄期的影响,进行无侧限抗压强度的系列试验,分析其应力-应变曲线、无侧限抗压强度、破坏应变、变形模量的变化规律,进而构建水泥固化锌离子污染黄土在无侧限条件下的应力-应变本构模型。研究表明,经水泥固化后的锌离子污染黄土应力-应变曲线为强软化型,试样呈脆性破坏,可分为弹性、弹塑性、应力下降、残余稳定4个阶段;随着养护龄期、水泥掺量的增加,无侧限抗压强度增大,破坏应变基本呈现减小趋势;变形模量与无侧限抗压强度呈现非线性关系;构建的考虑养护龄期、水泥掺量影响的应力-应变本构模型,可准确描述水泥固化锌离子污染黄土单轴压力下的变形全过程。

冷胁迫下普通油茶CCCH型锌指蛋白基因家族的鉴定和分析

【目的】为挖掘和利用耐寒普通油茶Camellia oleifera遗传资源提供参考。【方法】基于普通油茶的冷胁迫转录组数据,对其CCCH型锌指蛋白基因进行鉴定,并对CCCH型锌指蛋白进行理化性质分析、系统发育分析、保守结构域预测、二级结构预测等相关生物信息学分析,并以庐山高海拔油茶(LSG)和栽培油茶品种赣无1(GW1)为材料,对CCCH型锌指蛋白基因在冷胁迫下的表达情况进行分析。【结果】在普通油茶的冷胁迫转录组数据中共鉴定到24个CCCH型锌指蛋白基因,参考水稻分类方法,将24个CCCH型锌指蛋白聚类到2个亚家族中。保守基序分析结果表明,在24个基因中仅有3种CCCH型锌指蛋白基序类型,即C-X8-C-X5-C-X3-H、C-X7-C-X5-C-X3-H和C-X5-C-X4-C-X3-H,数目分别为92、4和4。转录组表达谱分析结果表明:在野外冷胁迫试验中CoC3H17基因在D4、D5和D6时期的表达量高于D1、D2和D3时期,在室内冷胁迫试验中庐山高海拔油茶和赣无1的CoC3H17基因一直表现为更高的转录本丰度;CoC3H14和CoC3H24基因在野外试验的D4、D5和D6时期均表现为表达量明显上升,且在室内冷胁迫试验中庐山高海拔油茶的这2个基因的表达量高于赣无1。【结论】CoC3H17、CoC3H14和CoC3H24基因可能是普通油茶应对冷胁迫的关键基因。

Antioxidant role of zinc in diabetes mellitus

Chronic hyperglycemia statue noticed in diabetes mellitus favors the manifestation of oxidative stress by increasing the production of reactive oxygen species and/or by reducing the antioxidant defense system activity.Zinc plays an important role in antioxidant defense in type2 diabetic patients by notably acting as a cofactor of the superoxide dismutase enzyme,by modulating the glutathione metabolism and metallothionein expression,by competing with iron and copper in the cell membrane and by inhibiting nicotinamide adenine dinucleotide phosphate-oxidase enzyme.Zinc also improves the oxidative stress in these patients by reducing chronic hyperglycemia.It indeed promotes phosphorylation of insulin receptors by enhancing transport of glucose into cells.However,several studies reveal changes in zinc metabolism in individuals with type 2 diabetes mellitus and controversies remain regarding the effect of zinc supplementation in the improvement of oxidative stress in these patients.Faced with the serious challenge of the metabolic disorders related to oxidative stress in diabetes along with the importance of antioxidant nutrients in the control of this disease,new studies may contribute to improve our understanding of the role played by zinc against oxidative stress and its connection with type 2 diabetes mellitus prognosis.This could serve as a prelude to the development of prevention strategies and treatment of disorders associated with this chronic disease.

QUANTITATIVE CHARACTERIZATION OF STRESS-STRAIN HYSTERESIS LOOPS OF Cu-Zn-Al SHAPE MEMORY ALLOY

A six-parameter mathematical model was introduced to simulate the stress-strain hysteresis and the sinner hysteresis of polycrystalline shape memory alloys (SMAs). By the comparison with experiments of Cu-Zn-Al SMA, it was shown that the model could be used to calculate the stress-strain relations with rather good accuracy. Moreover, it was found that the six parameters introduced in this paper represented the characteristics of the stress-strain hysteresis of polycrystalline SMAs and could be used to characterize the hysteresis quantitatively.