低能氩离子注入对固态尿嘧啶损伤的研究

对２５ｋｅＶ氩离子束辐照尿嘧啶（ｕｒａｃｉｌ）引起其分子结构的变化进行了研究,通过紫外光谱的分析,得到了离子注入后尿嘧啶的残余紫外吸收曲线,富里叶红外光谱仪的分析,说明尿嘧啶受到了一定程度的损伤,茚三酮反应的测定证明了辐照后的样品中出现了新的化学基团－氨基。     

keV离子辐照固态腺嘌呤与胞嘧啶的剂量效应研究

研究了经20keV的氮离子、氩离子辐照后,腺嘌呤与胞嘧啶的残存率与注入剂理的关系。结果表明,在相同的剂量下,氮离子对碱基的损伤比氩离子高,而对同种离子而言,胞嘧啶比腺嘌呤表现出较高的辐射敏感性。计算了碱基分子损伤的G值,比较它们随剂量的增大呈减小的趋势。考察了加入自由基清除剂后,碱基损伤剂量效应的变化。并对上述结果提出了初步的解释。     

氩离子对两种嘧啶碱基的损伤效应研究

对２５ｋｅＶ的氩离子束辐照两种嘧啶碱基（胞嘧啶,胞腺嘧啶）引起它们分子结构的变化进行了研究,通过紫外光谱的分析,得到了氩离子注入后两种嘧啶碱基的残余紫外吸收曲线;富里叶红外光谱仪的分析,说明两种嘧啶碱基各受到了一定程度的损伤使得红外吸收出现不同程度的减弱;茚三酮反应的测定证明了辐照后的样品中出现了新的化学成分－伯胺类物质。     

固态乙酸钠氮离子注入的辐照效应研究

用 ２５ｋｅ Ｖ 氮离子辐照固体乙酸钠样品,测定离子注入前后样品的紫外光谱,发现辐照后的样品中产生了新的具有紫外吸收的化学物质,给出了新物质的紫外吸收值的剂量效应关系式。通过高效液相色谱的分析测定,发现经氮离子束辐照后的乙酸钠样品中还产生了另一种新的化学基团一氨基,再结合茚三酮反应的检测,得到了离子束辐照剂量与新产物中氨基产生量的曲线关系。     

KeV离子辐照丙氨酸的剂量效应研究

研究了经２０ｋｅＶ的氢、氮及氩离子辐照后,丙氨酸的质量损失及自由基的产生情况。结果表明,ｋｅＶ离子辐照引起的丙氨酸分解不仅与离子的纵向作用有关还与离子的横向作用有关,这种横向作用是入射离子与靶原子级联碰撞产生的反冲原子造成的。ＫｅＶ离子辐照丙氨酸产生的自由基在较大剂量范围（４－１６０×１０１４ｉｏｎｓ／ｃｍ２）内有线性剂量响应,而且自由基的产生同样依赖于重离子的横向作用。这种横纵双重作用也较好地解释了自由基的转化。给出了较清晰的低能离子在生物（等效）材料中发生作用的物理图象。     

浙江辐照对离体质粒DNA的断裂效应

利用低功率的Ｈｅ－Ｎｅ激光辐照离体质粒ＤＮＡ,并用离子束和紫外线为对照,分析了质粒ＤＮＡ的单双链断裂效应。结果表明：Ｈｅ－Ｎｅ激光辐照可诱发质粒ＤＮＡ断裂,且断裂频率辐照剂量增大而提高;Ｈｅ－Ｎｅ激光辐照后的质粒超螺旋双链的ＤＮＡ存活率剂量曲线不同于紫外线和氮离子束。Ｈｅ－Ｎｅ激光诱发双链断裂的频率低于氮离子束和紫外线。     

激光辐照对离体质粒DNA的断裂效应

利用低功率的Ｈｅ－ Ｎｅ 激光辐照离体质粒ＤＮＡ,并用离子束和紫外线为对照,分析了质粒ＤＮＡ的单双链断裂效应。结果表明：Ｈｅ－ Ｎｅ 激光辐照可诱发质粒ＤＮＡ 断裂,且断裂频率随辐照剂量增大而提高;Ｈｅ－ Ｎｅ 激光辐照后的质粒超螺旋双链ＤＮＡ存活率剂量曲线不同于紫外线和氮离子束。Ｈｅ－ Ｎｅ 激光诱发双链断裂的频率低于氮离子束和紫外线。     

酱驴肉辐照贮藏技术研究

目的：分析探讨γ 射线辐照处理对酱驴肉的贮藏效果，建立适宜的辐照加工工艺参数。方法：采用不同剂量的60Coγ 射线对铝箔袋真空包装酱驴肉进行辐照处理，分析测定室温贮藏过程中，样品菌落总数、挥发性盐基氮等品质指标的变化。结果：2.0k～10.0kGy的不同辐射剂量处理能够有效杀死肉品表面污染微生物，抑制贮藏过程中菌落总数的增加，剂量越大杀菌效果越好，同时减缓了样品pH值上升和挥发性盐基氮含量的增加，但是对样品的色泽指标（L*值、a*值、b*值）和质构指标硬度、粘聚性的影响作用不明显。     

辐照对水溶液中亚硝酸盐降解效果研究

以亚硝酸盐水溶液为研究对象,研究了辐照剂量、亚硝酸盐初始浓度、Vc和NaCl含量对亚硝酸盐降解效果的影响.结果表明,辐照能有效降低水溶液中亚硝酸盐含量,亚硝酸盐降解率与辐照剂量呈正相关,与初始浓度呈负相关,Vc对辐照降解亚硝酸盐具有协同作用,NaCl对辐照降解亚硝酸盐具有抑制作用.亚硝酸盐水溶液经辐照后,硝态氮和铵态氮均有一定的增加,当辐照剂量为10.55 kGy,初始浓度为100 mg· L-1时,硝态氮含量由14.857 mg·L-1增加到17.270 mg·L-1,铵态氮含量由0.013 mg·L-1增加到0.041 mg·L-1.     

不同波长Ar^＋激光对啤酒酵母菌的诱变效应

本文应用514.5nm,496.5nm、488.0nm和476.5nm等四种不同波长的氩离子辐照啤酒酵母菌,激光辐照的功率密度300mw/cm~2、辐照时间12min。辐照后进行细胞培养和啤酒发酵试验,并测定细胞有关生理性能的变化。实验表明,上述四种波长的Ar~+激光对啤酒酵母细胞的生长繁殖和代谢主产物乙醇的生物合成有明显的促进作用,并能提高双乙酰还原酶的活力,降低发酵付产物双乙酰的含量。这些变化,有利于缩短啤酒发酵的周期,提高啤酒产量相改善啤酒的风味。     

Effect of shear stress and free radicals induced by ultrasound on erythrocytes

The present study was undertaken to elucidate the mechanism of hemolysis induced by ultrasound. Ar or N2O gas was used to distinguish between cavitation with or without free radical formation (hydroxyl radicals and hydrogen atoms). Free radical formation was examined by the method of spin trapping combined with ESR. After sonication of erythrocyte suspensions, several structural and functional parameters of the erythrocyte membrane--hemolysis, membrane fluidity, membrane permeability, and membrane deformability--were examined. Although free radical formation was observed in the erythrocyte suspensions sonicated in the presence of Ar, no free radical formation was observed in the presence of N2O. However, the hemolysis behavior induced by ultrasound was similar in the presence of Ar or N2O. The membrane fluidity, permeability, and deformability of the remaining unlysed erythrocytes after sonication in the presence of Ar or N2O were unchanged and identical to those of the control cells. On the other hand, after gamma irradiation (700 Gy), the hemolysis behavior was quite different from that after sonication, and the membrane properties were significantly changed. These results suggest that hemolysis induced by sonication was due to mechanical shearing stress arising from cavitation, and that the membrane integrity of the remaining erythrocytes after sonication was the same as that of control cells without sonication. The triatomic gas, N2O, may be useful for ultrasonically disrupting cells without accompanying free radical formation.     

Absence of synergistic enhancement of non-thermal effects of ultrasound on cell killing induced by ionizing radiation

The present study was performed to elucidate the role of non-thermal effects (cavitation and direct effects) of ultrasound, in simultaneous combination with X-irradiation on the cytotoxicity of mouse L cells. Firstly, mouse L cells were exposed to X-rays and ultrasound (1 MHz continuous wave, spatial peak temporal average intensity; 3.7 W/cm2) simultaneously at 37 degrees C under O2 or Ar saturated conditions to examine the cavitational effect of ultrasound. Secondly, cells were exposed to X-rays and ultrasound at 37 degrees C under N2O saturated conditions, which suppresses the cavitation, to examine the direct effects of ultrasound. The cavitational effect under O2 and Ar saturated conditions induced an exponential decrease in cell survival, and resulted in an additive effect on cell killing with the combination of X-rays and ultrasound. The direct effect in the N2O conditions induced no cell killing and did not modify the cell killing induced by X-rays. These results suggested that the non-thermal effects of ultrasound did not interact synergistically with X-rays for cell killing.     

不同离子辐照对离体质粒DNA损伤与转化活性的影响

利用 30Kev的N+ 、Ar+ 离子辐照离体质粒DNA ,分析了不同离子对DNA单双链断裂及转化活性的影响。结果表明 :N+ 、Ar+ 离子辐照均可引起质粒DNA单双链断裂和转化活性的变化 ,且随着辐照剂量的增加 ,单双链断裂频率增加 ,转化活性下降。Ar+对离体质粒DNA比N+ 具有更强的单双链断裂效应 ,且从 9× 10 15Ar+ cm2 剂量开始 ,质粒可完全丧失转化活性。质粒转化活性的大小与DNA单双链断裂频率呈正相关     

Gravitational independence of single-breath washout tests in recumbent dogs

To examine the mechanisms of lung filling and emptying, Ar-bolus and N2 single-breath washout tests were conducted in 10 anesthetized dogs (prone and supine) and in three of those dogs with body rotation. Transpulmonary pressure was measured simultaneously, allowing identification of the lung volume above residual volume at which there was an inflection point in the pressure-volume curve (VIP). Although phase IV for Ar was upward, phase IV for N2 was small and variable, especially in the prone position. No significant prone to supine differences in closing capacity for Ar were seen, indicating that airway closure was generated at the same lung volumes. The maximum deflections of phase IV for Ar and N2 from extrapolated phase III slopes were smaller in the prone position, suggesting more uniform tracer gas concentrations across the lungs. VIP was smaller than the closing volume for Ar, which is consistent with the effects of well-developed collateral ventilation in dogs. Body rotation tests in three dogs did not generally cause an inversion of phase III or IV. We conclude that in recumbent dogs regional distribution of ventilation is not primarily determined by the effect of gravity, but by lung, thorax, and mediastinum interactions and/or differences in regional mechanical properties of the lungs.     

Hydrogenase activity of Chlorella vulgaris cells

Cell suspensions of Chlorella vulgaris were found to possess the hydrogenase activity as was confirmed by their ability to absorb H2 in the presence of benzyl viologen, azocarmine and other hydrogen acceptors as well as to produce H2 from reduced methyl viologen. Incubation of the cells in the dark under anaerobic conditions in the atmosphere of H2, N2 or Ar stimulated the activity of hydrogenase and induced its de novo synthesis. Treatment of the cells adapted to anaerobiosis with dry ice or liquid nitrogen considerably increased their hydrogenase activity. The enzyme of the adapted cells was more resistant to the inactivation by O2 and temperature.     

Effects of n(2) deficiency on transport and partitioning of C and N in a nodulated legume

Nodulated root systems of white lupin (Lupinus albus L. cv Ultra: Rhizobium strain WU425) were exposed to Ar:O₂ (80:20, v/v) or Ar:N₂:O₂ (70:10:20, v/v/v) and C and N partitioning were examined over a 9- or 10-day period in comparison with control plants with nodulated roots retained in air. Accumulation of N ceased in plants exposed to Ar:O₂ or was much reduced in plants exposed to Ar:N₂:O₂, but net C assimilation rates and profiles of C utilization remained similar to those of control N₂-fixing plants. There was, however, a proportional reduction in CO₂ evolution from nodulated roots of the Ar:O₂ treatment. Xylem N levels fell rapidly after application of Ar:O₂. C:N ratios of phloem sap of petioles and of stem base rose during the first day of Ar:O₂ treatment and then fell progressively back to levels close to that of control plants as leaf reserves of N became available for loading of phloem. Stem top phloem sap increased progressively in C:N ratio throughout Ar:O₂ treatment, presumably due to increasing shortage of xylem derived N for xylem to phloem exchange. Reexposure of Ar:O₂-treated nodulated root systems to air prompted a rapid recovery of N₂ fixation and restoration of plant N status. Rates of N₂ fixation in plants whose roots were exposed to a range of N₂ concentrations indicated an apparent K_m of 10% N₂ for the attached intact white lupin nodule.     

Mixed-gas model for predicting decompression sickness in rats.

A mixed-gas model for rats was developed to further explore the role of different gases in decompression and to provide a global model for possible future evaluation of its usefulness for human prediction. A Hill-equation dose-response model was fitted to over 5,000 rat dives by using the technique of maximum likelihood. These dives used various mixtures of He, N(2), Ar, and O(2) and had times at depth up to 2 h and varied decompression profiles. Results supported past findings, including 1) differences among the gases in decompression risk (He < N(2) < Ar) and exchange rate (He > Ar approximately N(2)), 2) significant decompression risk of O(2), and 3) increased risk of decompression sickness with heavier animals. New findings included asymmetrical gas exchange with gas washout often unexpectedly faster than uptake. Model success was demonstrated by the relatively small errors (and their random scatter) between model predictions and actual incidences. This mixed-gas model for prediction of decompression sickness in rats is the first such model for any animal species that covers such a broad range of gas mixtures and dive profiles.     

Stabilities of Suspensions of Influenza Virus Dried by Sublimation of Ice In Vacuo to Different Contents of Residual Moisture and Sealed Under Different Gases

Suspensions of influenza virus were dried by sublimation of ice in vacuo to contents of residual moisture of 2.8, 1.6, or 0.6%. After drying, the preparations were sealed under helium, argon, nitrogen, or a mixture of oxygen and nitrogen (30% O(2), 70% N(2)). Stabilities of the several preparations were determined by an accelerated storage test. Based on the times predicted for the dried preparations stored at preselected temperatures to lose 1 log of infectivity titer, the order of stabilities in relation to residual moisture, gas was as follows: 1.6%, He > 0.6%, He > 2.8%, He > 1.6%, Ar > 2.8%, N(2) > 2.8%, Ar > 1.6%, N(2) > 2.8%, O(2) > 0.6%, Ar > 0.6%, N(2) > 1.6%, O(2) > 0.6%, O(2). The stability of the preparation sealed under helium and dried to the content of residual moisture found best for this gas (1.6%) resulted in an increased stability of the order of years as compared to the other preparations tested.