低温胁迫对青椒膜脂代谢的影响

目的为了研究低温胁迫对青椒膜脂代谢的影响。方法以“晋黎”青椒为实验材料,测定10℃(对照)和4℃(低温胁迫)等不同贮藏温度下青椒相对电导率、丙二醛(MDA)、脯氨酸、磷脂酶D(PLD)、脂氧合酶(LOX)活性、脂肪酸组分的变化情况。结果在低温胁迫下,青椒的相对电导率升高,MDA积累,脯氨酸含量增加,PLD和LOX活性升高,亚油酸、亚麻酸减少,硬脂酸增加,脂肪酸不饱和指数降低。结论低温胁迫诱导青椒PLD和LOX活性上升,引起不饱和脂肪酸降解,饱和脂肪酸增加,膜流动性减弱,最终导致膜失去完整性,在这过程中脯氨酸含量明显升高。     

茭白茎部CTK及ABA含量动态变化分析

通过比较分析正常茭白与灰茭两种膨大表型茎部发育期间的CTK和ABA含量的动态变化,探索茭白茎部菰黑粉菌生长分布与CTK和ABA含量变化的调节关系.本实验以灰茭和正常茭不同发育时期茎部为实验材料,并采用酶联免疫吸附分析法(简称ELISA)测定实验材料内CTK和ABA的含量,结果表明,灰茭茎部CTK含量峰值出现在孢子形成期,可能与灰孢子的增殖有关,而正常茭出现在分蘖期,可能与茭白组织不断分裂有关;ABA激素在灰茭茎部含量一直较高,在孢子形成期后期达到峰值,正常茭在8叶期和膨大期较高,内源激素ABA的高水平表达可能是由菰黑粉菌侵染茭白以及大量繁殖引起的.总体上CTK和ABA在灰茭和正常茭白内的关系不是单一的,而是相辅相成的.     

低温对西番莲采后贮藏品质的影响

目的 探究低温贮藏对西番莲采后贮藏保鲜效果的影响.方法 以西番莲为实验材料,检测西番莲果实的皱缩指数、质量损失率、好果率、色差、相对电导率、丙二醛含量、可溶性固形物含量、可滴定酸含量、Vc含量、可溶性蛋白含量和SOD酶活性等生理生化指标的变化,研究低温贮藏(3,8,13℃)对西番莲采后生理和营养品质的影响.结果 在8℃下贮藏的保鲜效果优于3,13℃组,其可以有效地维持果实的色泽和好果率,抑制质量损失率、皱缩指数、相对电导率和丙二醛含量的增加,保持较好的可溶性固形物、可滴定酸、Vc、可溶性蛋白含量,提高果实的SOD酶活性,较好地保持了果实的贮藏品质.结论 西番莲采后在8℃下贮藏对果实贮藏保鲜的效果最佳,可以有效地延缓果实衰老.     

茭白黑粉菌核相变化及ISSR分子标记筛选的研究

通过显微观察和Hoechst 33258荧光染色方法,系统观察了茭白灰茭中黑粉菌厚垣孢子不同萌发时期的核相变化.研究表明,厚垣孢子萌发过程中黑粉菌细胞核的数目不断变化,核相在萌发过程中是不规则的.茭白灰茭厚垣孢子中没有观察到细胞核,菌丝体细胞核的数目在1~4个,大多数小孢子仅有一个细胞核或没有细胞核.同时获得了18个可用于茭白黑粉菌遗传变异分析的ISSR分子标记,作为深入探讨茭白黑粉菌的生物学特性的参考.     

气调包装联合保鲜剂对‘塞外红’苹果中短期贮藏的影响

目的 探究不同贮藏温度、气调包装及保鲜剂对‘塞外红’苹果贮藏品质的影响。方法 采用冷藏、气调包装(O2与CO2的体积比为5∶1)以及复合保鲜剂(1-甲基环丙烯、CaCl2、甜菜碱)等处理方式，对新鲜采摘的‘塞外红’苹果进行60 d的贮藏实验，分析贮藏期间苹果的质构特性、呼吸强度、外观品质、褐变指数、可滴定酸含量、可溶性固形物含量、抗坏血酸含量、相对电导率、丙二醛含量的变化。结果 在贮藏温度0.5 ℃下，采用气调包装结合保鲜剂处理能够有效抑制‘塞外红’苹果的褐变指数、丙二醛含量和相对电导率的增加。与单独进行0.5 ℃冷藏处理相比，经过60 d贮藏，处理后苹果的褐变指数、丙二醛含量和相对电导率分别降低了42%、66%、14%。同时，该处理方式延缓了‘塞外红’苹果质构特性的下降，降低了果实的呼吸强度，并保持了较高的抗坏血酸、可溶性固形物和可滴定酸等含量。结论 在0.5 ℃下冷藏并配合气调包装和外源保鲜剂处理可以有效地抑制‘塞外红’苹果的细胞损伤和营养物质的损失，延缓苹果品质的恶化进程。     

软枣猕猴桃后熟过程中生理及品质变化规律

目的 研究不同的软枣猕猴桃品种在后熟衰老过程中生理及品质变化规律,及其差异性产生的内在原因.方法 将"桓优1号"和"龙成2号"软枣猕猴桃置于(20±1)℃下贮藏7 d,每天测定其呼吸代谢、营养成分、抗氧化物质含量及相关酶活性等生理指标,同时利用透射电镜进行超微结构观察.结果 "龙成2号"软枣猕猴桃的呼吸强度较高,果实硬度相对较低,并且有较高的可溶性固形物(TSS)含量、总酚含量、类黄酮含量、Vc含量和多酚氧化酶(PPO)活性."桓优1号"的呼吸代谢缓慢,但过氧化物酶(POD)活性较高.通过对果实超微结构的观察,发现"龙成2号"在贮藏后期中胶层和细胞壁已经降解,结构松散且不完整,然而"桓优1号"的细胞壁和细胞膜结构相对完整.结论 "桓优1号"因其呼吸代谢缓慢,耐贮性更好,但口感较差,而"龙成2号"具有较好的营养风味品质和抗氧化等特性,但其耐贮性较差.研究结果将有助于合理选择软枣猕猴桃的栽培品种.     

利用叶绿素荧光参数筛选抗盐菊芋品种的初步研究

对砂培菊芋幼苗试验材料("大丰"品种(耐盐性较强)和"无锡"品种(耐盐性较弱))分别进行了不同 NaCl 浓度(0、50、100、150mmol/L)的胁迫处理,利用叶绿素荧光测定技术,对"大丰"和"无锡"的生物量、叶绿素含量、叶绿素荧光参数和净光合速率(Pn)的变化进行了研究.结果表明,NaCl 胁迫显著影响植株生物量、叶片叶绿素含量、叶绿素荧光参数和Pn,但"大丰"幼苗生长受盐胁迫的影响小于"无锡",其光合机构受盐胁迫的伤害程度小于"无锡";叶片叶绿素含量的下降与荧光参数和Pn的变化呈极显著相关关系,叶片的叶绿素荧光参数和Pn的显著变化同步于叶绿素含量的下降.因此,叶绿素荧光参数可作为菊芋抗盐品种筛选的诊断指标之一.     

南极冰藻Chlamydomonas sp. L4的UV-B辐射效应研究

实验研究了从南极采集的冰藻Chlamydomonas sp. L4经强UV-B辐射胁迫后的生物学效应及逆境适应性.研究显示,经过强UV-B胁迫,冰藻L4细胞内迅速产生大量的活性氧,丙二醛含量升高;同时,SOD活性快速提高,使活性氧和丙二醛含量维持在细胞容许范围之内.膜脂肪酸成分分析发现不饱和指数增加了近4倍,膜流动性增加 ,从而维持膜的正常功能.光学显微镜、扫描和透射电镜观察表明,UV-B辐射使细胞体积显著增大,黏性多糖分泌增多,细胞壁增厚,未知黑色颗粒密度增加,L4可能通过上述结构变化把 UV-B屏蔽在胞外.脂肪颗粒的增加是细胞在逆境生存的能量保障.此外,细胞中类囊体片层、线粒体和细胞核等结构基本没有变化,维持细胞基本的代谢和能量供应.     

南极冰藻(硅藻)细胞质中无机离子的变化与低温适应性的关系

利用X-射线微区分析方法研究了南极冰藻在不同温度条件下体内身体重要的无机离子的变换，发现低温条件可以诱导南极冰藻（硅藻G）细胞质内的钙离子水平在短期大幅度增加，但随后随时间的延长而下降。这表明，低温能够诱导钙离子向细胞质内流入并发挥其信使功能，从而使抗冷基因得到表达而使南极冰藻具有抗冷的性质，低温也使硅藻G细胞质内的其他无机离子含量迅速增加，这种变化可能是南极冰藻抵抗不良的环境胁迫所主动发挥作用的结果。     

间歇热处理对柑橘冷害调控研究

目的 针对柑橘低温贮藏易冷害问题,研究间歇热处理对柑橘冷害的调控效果。方法 以浙江省衢州市沃柑品种为实验材料,采用连续热处理（50 ℃下热水处理180 s）和间歇热处理（50 ℃下热水处理60 s—20 ℃常温下回温10 min—50 ℃下热水处理60 s—20 ℃常温下回温10 min—50 ℃下热水处理60 s—20 ℃常温下回温10 min）等2种方式处理柑橘。结果 与对照组相比,热处理能够降低柑橘的冷害指数,抑制相对电导率和丙二醛（MDA）含量的上升,提高柑橘的过氧化物酶（POD）和超氧化物歧化酶（SOD）活性,且间歇热处理组柑橘的抗冷效果显著优于连续热处理组（P<0.05）。贮藏50 d后,间歇热处理组的冷害指数比对照组低19.32%,MDA质量摩尔浓度分别比对照组和连续热处理组低0.91 μmol/g和0.37 μmol/g,POD活性分别较对照组和连续热处理组增加了0.72倍和0.19倍,SOD活性分别比对照组和连续热处理组增加5.231 U/g和1.776 U/g。结论 热处理能够延缓柑橘冷害,且间歇热处理对沃柑的保鲜效果优于连续热处理。     

Silicon-enhanced resistance to cadmium toxicity in Brassica chinensis L. is attributed to Si-suppressed cadmium uptake and transport and Si-enhanced antioxidant defense capacity

A series of hydroponics experiments were performed to investigate roles of silicon (Si) in enhancing cadmium (Cd) tolerance in two pakchoi (Brassica chinensis L.) cultivars: i.e. cv. Shanghaiqing, a Cd-sensitive cultivar, and cv. Hangyoudong, a Cd-tolerant cultivar. Plants were grown under 0.5 and 5 mg Cd L⁻¹ Cd stress without or with 1.5 mM Si. Plant growth of the Cd-tolerant cultivar was stimulated at the lower Cd level, but was decreased at the higher Cd level when plants were treated with Cd for one week. However, Plant growth was severely inhibited at both Cd levels as stress duration lasted for up to three weeks. Plant growth of the Cd-sensitive cultivar was severely inhibited at both Cd levels irrespective of Cd stress duration. Addition of Si increased shoot and root biomass of both cultivars at both Cd levels and decreased Cd uptake and root-to-shoot transport. Superoxide dismutase, catalase and ascorbate peroxidase activities decreased, but malondialdehyde and H₂O₂ concentrations increased at the higher Cd level, which were counteracted by Si added. Ascorbic acid, glutathione and non-protein thiols concentrations increased at the higher Cd level, which were further intensified by addition of Si. The effects of Si and Cd on the antioxidant enzyme activity were further verified by isoenzyme analysis. Silicon was more effective in enhancing Cd tolerance in the Cd-tolerant cultivar than in the Cd-sensitive cultivar. It can be concluded that Si-enhanced Cd tolerance in B. chinensis is attributed mainly to Si-suppressed Cd uptake and root-to-shoot Cd transport and Si-enhanced antioxidant defense activity.     

Role of turmeric in oxidative modulation in end‐stage renal disease patients

Oxidative stress is considered as a major player in uremia‐associated morbidity and mortality in hemodialysis (HD) patients. The aim of this study was to evaluate the effects of turmeric on oxidative stress markers in HD patients. This study was a prospective and double‐blind randomized clinical trial. Fifty HD patients aged 18–60 years were recruited after fulfilling the inclusion criteria. Patients were randomly categorized into 2 groups: trial group received turmeric and control group received placebo for 8 weeks. Each patient in the trial group received turmeric, whereas the control group received starch for the same 8 weeks. Plasma malondialdehyde (MDA), red blood cell (RBC) antioxidant enzyme activities as glutathione peroxidase (GPX), glutathione reductase (GR), and catalase (CAT), cholesterol, high‐density lipoprotein‐cholesterol, low‐density lipoprotein‐cholesterol, triglyceride, albumin, and hemoglobin were also measured before and after study. Although MDA level was reduced in both groups, the ratio of decrease was significantly higher in the turmeric group (0.2 vs. 0.1, P = 0.040). Three enzymes of GPX, GR, and CAT levels were increased in both groups; the ratio of increased was significantly higher in the turmeric group for the CAT enzyme (0.73 vs. 0.54; P = 0.02). Also, significant elevation of albumin level in the turmeric group compared with the control group was observed (P = 0.001). Regular ingestion of turmeric reduces plasma MDA and increases RBC CAT activity and plasma albumin levels in HD patients. Turmeric showed no adverse effects.     

振动胁迫对双孢蘑菇活性氧代谢和抗氧化性能的影响

以新鲜的双孢蘑菇为原材料,研究了3 Hz振动频率下经过1, 2 h的振动处理（以未经振动的双孢蘑菇作对照）对双孢蘑菇色泽、活性氧代谢和抗氧化性能的影响。结果表明：振动胁迫加速了双孢蘑菇超氧阴离子（O2-）的产生和过氧化氢（H2O2）含量的积累,不同振动时间下双孢蘑菇产生的O2-活力是对照组的2.89倍（1 h）和3.31倍（2 h）,H2O2含量是对照组的1.38倍（1 h）和1.56倍（2 h）;振动胁迫诱导超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、抗坏血酸过氧化物酶（APX）等抗氧化酶活性迅速升高,相对电导率、丙二醛（MDA）含量大幅上升,抗坏血酸加速分解,总酚、类黄酮含量和多酚氧化酶（PPO）酶活性峰值提前出现。振动胁迫后的双孢蘑菇活性氧自由基大量积累,细胞膜氧化损伤加剧,最终加速了双孢蘑菇的褐变。     

Al2O3纳米粉体悬浮液热物性实验研究

分别采用瞬态热线法、比较量热法和旋转粘度计测试了不同温度、粒子浓度和粒径下的Al2O3-DW（蒸馏水）纳米流体的导热系数、比热容、粘度等热物性参数。试验结果表明,粒子浓度、粒径和温度都是影响Al2O3-DW纳米流体热物性参数的重要因素。与水相比,纳米流体导热系数和粘度增加,常温4％体积份额下增幅分别为21．5％和52．3％;纳米流体比热容随着粒子体积份额增加而降低,并推导出了常温下低浓度纳米流体比热容的预测公式。     

Oxidative DNA damage correlates with carotid artery atherosclerosis in hemodialysis patients

Oxidative stress is accepted as a nonclassical cardiovascular risk factor in chronic renal failure patients. The aim of this study was to evaluate the relation between oxidative DNA damage (8‐hydroxy‐2′‐deoxyguanosine/deoxyguanosine [8‐OHdG/dG] ratio), oxidative stress biomarkers, antioxidant enzymes, and carotid artery intima‐media thickness (CIMT) in hemodialysis (HD) patients. Forty chronic HD patients without known atherosclerotic disease and 48 age‐ and sex‐matched healthy individuals were included in the study. Plasma malondialdehyde (MDA) levels and 8‐OHdG/dG ratio were determined as oxidative stress markers. Superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities were measured as antioxidants. CIMT was assessed by carotid artery ultrasonography. 8‐OHdG/dG ratios and MDA levels were higher; SOD and GPx activities were lower in HD patients compared to controls. HD patients had significantly higher CIMT compared to controls (0.61 ± 0.08 vs. 0.42 ± 0.05, p < 0.001). There was a significant positive correlation between CIMT and 8‐OHdG/dG ratio (r = 0.57, p < 0.01) and MDA levels (r = 0.41, p < 0.01), while there was a significant negative correlation between CIMT and SOD (r = ?0.47, p < 0.01) and GPx levels (r = ?0.62, p < 0.01). It is firstly demonstrated that CIMT is positively correlated with oxidative DNA damage in HD patients without known atherosclerotic disease.     

微波烧结制备ZrO2-AlN复合陶瓷的微观结构与性能研究

氧化锆(ZrO₂)陶瓷具有出色的机械性能, 但其应用受到低热导率(Thermal Conductivity, TC)的限制。本研究设计并通过微波烧结制备了高热导率氧化锆-氮化铝(AlN)复合陶瓷, 优化制备条件后, 抑制了两种物质之间的反应, 获得了致密的复合陶瓷(相对密度>99%), 详细研究了该复合陶瓷的组织演变、热学性能和力学性能。研究结果表明, 随着AlN含量的增加, 复合陶瓷的室温下热导率、热扩散系数和热容增加, 分别达到41.3 W/(m·K)、15.2 mm²/s和0.6 J/(g·K)。这种具有高热导率和抗热震性的ZrO₂-AlN复合复合陶瓷在能源系统的高温热交换材料领域具有广阔的应用前景。     

Febuxostat improves endothelial function in hemodialysis patients with hyperuricemia: A randomized controlled study

Endothelial dysfunction is often found in both hyperuricemia and hemodialysis patients. Recent studies have shown that treating hyperuricemia with allopurinol improves endothelial dysfunction. This study is performed to assess the effect of febuxostat on endothelial dysfunction in hemodialysis patients with hyperuricemia. We randomly assigned 53 hemodialysis patients with hyperuricemia to a febuxostat (10 mg daily) group and a control group and measured flow‐mediated dilation, serum uric acid (UA) levels, systolic and diastolic blood pressure, malondialdehyde‐modified low‐density lipoprotein (MDA‐LDL), and highly sensitive C‐reactive protein (hsCRP) at baseline and at the end of a 4‐week study period. Flow‐mediated dilation increased from 5.3% ± 2.4% to 8.9% ± 3.6% in the febuxostat group but did not change significantly in the control group. Treatment with febuxostat resulted in a significant decrease in serum UA level and a significant decrease in MDA‐LDL compared with baseline, but no significant difference was observed in hsCRP level or blood pressure. No significant differences were observed in the control group. Febuxostat improved endothelial dysfunction and reduced serum UA levels and oxidative stress in hemodialysis patients with hyperuricemia.     

Synthesis of nanocrystalline Ce(0.8)Gd(0.2)O(2-delta) electrolyte materials for IT-SOFC

We successfully synthesized nano-sized Ce(0.8)Gd(0.2)O(2-delta) powders by combustion method, using gelatin as fuel. The calcined powders showed high-quality characteristics, i.e., nano-scale size (14-35 nm) and narrow size distribution. The structural, morphological, and electrical characteristics of the sintered Ce(0.8)Gd(0.2)O(2-delta) were studied systematically, depending on sintering temperature. The crystal structure of the Ce(0.8)Gd(0.2)O(2-delta) belonged to the cubic fluorite structure. The gelatin-assisted combustion synthesized Ce(0.8)Gd(0.2)O(2-delta) powders allowed to sinter well at low temperature for dense and ultra-fine Ce(0.8)Gd(0.2)O(2-delta) electrolyte with good electrical conductivity. The sintering temperature of the Ce(0.8)Gd(0.2)O2 powder was approximately 300 degrees C lower than that of conventional solid-state synthesized powder. The nanopowder produced was sintered into pellets with relative densities over 99.1% of the theoretical value even at 1400 degrees C. The Ce(0.8)Gd(0.2)O(2-delta) sintered at 1400 degrees C exhibited a conductivity of 0.101 S/cm at 800 degrees C in air.