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121.
M. Rommel E.-J. Langrock H. Baumbach 《Isotopes in environmental and health studies》2013,49(2):203-209
At the Leipzig Technical University a method was developed, which allows to determine nondestructive the crack depth in concrete up to 15 cm. Based on a radiotracer technique the access to only one side of the object is required. The labelling of artificial-made cracks was carried out by use of a transport medium (not miscible with water) on the base of methyl isobutyl ketone (MIBK) and In- 113m as radionuclide. For the calculation of crack depth, measure-geometrical parameters were used. The improvement of the reliability of building-diagnostical interpretation using radio-physical parameters is described. A first application is provided for concrete structures below chemical equipments built as a barrier against ecologically harmful substances (petrol tanks). The intersectional aspect of further qualifications of the technique is emphasized. 相似文献
122.
Es wurde eine Methode zur Bestimmung von Stoffen durch eine Fällungstitration unte Anwendung von radioaktiven Kryptonaten als Redox-Indikatoren entwickelt. Als ein praktisches Beispiel wird die Bestimmung von Ba2+ durch eine Titration mit K2Cr2O7 als Maβlösung und Ag[85Kr] als Äquivalenzpunktindikator angeführt. Bis zum Erreichen des Äquivalenzpunktes verläuft die Fällungsreaktion unter Bildung des Niederschlages von BaCrO4 und nach Überschreiten des Åquivalenzpunktes eine Redox-Reaktion zwischen der Maβlösung und dem radioaktiven Kryptonat, wobei 85 Kr freigesetzt wird. 相似文献
123.
Abstract The problem concerning qualification of food originated from animals irradiated and contaminated with 137caesium appeared especially after the Chernobyl accident. So, it was a reason to undertake respective studies on 108 rabbits divided into three groups: group I – non-irradiated rabbits, group II – irradiated with a dose of 103 mCkg?1 (400 R), group III – irradiated with a dose of 206 mCkg?1 (800 R). All animals were contaminated intragastrically with an aqueous solution of 137CsCl. After slaughter samples of the muscles were cured in 1, 3, 5, 10, and 15% brine or were cooked for 2 hrs. In the case of curing the radioactivities of meat and brine, and the concentrations of salt in cured meat were estimated after 7, 14, and 21 days. The radioactivities of cooked meat, broth, and condensed water vapour were estimated after 1 and 2 hrs. Taking into account the decrease of the radioactivities, duration of curing, and concentrations of salt in cured meat the optimum results were achieved when the meat from non-irradiated rabbits was cured for 7 days in 3% brine, and that of irradiated rabbits in 5% brine with regard to a lower stability of this meat. The decontamination effectiveness of cooking was similar in all examined rabbits. Radiocaesium penetrates into the brine or broth and escapes with water vapour thereafter. 相似文献
124.
125.
The effect of pre or post-administration of vitamin A in ameliorating the radiation-induced alteration in intestinal and spleen Na+/K+-ATPase activity of rats was determined. Rats subjected to multifractionated γ-radiation (20 × 0.5 Gy) over the whole-body showed a significant reduction in Na+/K+-ATPase activity being more obvious in spleen than in intestine. Administration of vitamin A at a daily i. p. dose of 15,000 IU/kg bd. wt. for 7 days prior to fractionated γ-irradiation and thereafter twice weekly throughout the exposure period (as pretreatment regimen) or following the end of irradiation for 7 days (as posttreament regimen) afforded a significant protection from radiation-induced inhibition of spleen and intestinal Na+/K+-ATPase activity. Even though, pretreatment regimen is more efficient against radiation injury to this enzyme than posttreatment, so that its activity was nearly normalized in the first regimen. The regeneration of normal enzyme activity in the tissues of the vitamin A-pretreated group suggests that the intestinal and spleen epithelia in presence of vitamin A are rendered relatively radioresistant. 相似文献
126.
饱和铁芯型超导限流器SCFCL(Saturated Core Superconducting Fault Current Limiter)是一种较为理想的高电压限流器,利用其技术特点可以实现无时限的明显限流作用,有着广泛的运用前景。距离保护能够很好的满足高电压复杂网络快速、精确切除故障的要求,其主要元件阻抗继电器是现阶段普遍应用的高性能继保装置。SCFCL在高压输电网络的接入会对距离保护产生很大影响,运用PSCAD搭建500kV输电线路模型,详细分析限流器接入前后不同短路故障类型及故障距离对线路距离保护的影响。 相似文献
127.
A system of two initially entangled qubits interacting with a bosonic environment is considered. The interaction induces a loss of the initial entanglement of the two qubits, and for specific initial states it causes entanglement sudden death. An investigation of the modifications on the entanglement dynamics by a single pulse control field, performed in the two qubit system, shows that the control field can not only protect entangled states against sudden death but also induce a revival of entanglement in the two qubit system. 相似文献
128.
James W. Favell Osei B. Fordwour Sydney C. Morgan Ieva Zigg Wesley F. Zandberg 《Molecules (Basel, Switzerland)》2021,26(14)
Smoke taint in wine is thought to be caused by smoke-derived volatile phenols (VPs) that are absorbed into grape tissues, trapped as conjugates that are imperceptible by smell, and subsequently released into wines as their free odor-active forms via metabolism by yeasts during fermentation. Blocking VP uptake into grapes would, therefore, be an effective way for vineyards to protect ripening grape crops exposed to smoke. Here, we re-evaluated a biofilm that had previously shown promise in pilot studies in reducing levels of smoke-derived VPs. A suite of nine free and acid-labile VPs were quantitated in Pinot Noir grapes that had been exposed to smoke after being coated with the biofilm one, seven or 14 days earlier. In contrast with earlier studies, our results demonstrated that in all cases, the biofilm treatments led to increased concentrations of both free and total VPs in smoke-exposed grapes, with earlier applications elevating concentrations of some VPs more than the later time points. Tracking VP concentrations through the grape ripening process demonstrated that some (phenol, p/m-cresol, and guaiacol) were not entirely sequestered in grapes as acid-labile conjugates, suggesting the presence of VP storage forms beyond simple glycosides. Free VPs in grapes, though a minor portion of the total, most clearly correlated with concentrations present in the resulting wines. Finally, red table grapes, available year round, were observed to replicate the effects of the biofilm treatments and were capable of transforming most VPs into acid-labile conjugates in under 24 h, indicating that they might be an effective model for rapidly assessing smoke-taint prophylactic products in the laboratory. 相似文献
129.
A novel architecture for an optical time-division switch is investigated and demonstrated at a bit rate of 625 Mbit/s. The self-clocked configuration eliminates some of the limitations found in previous optical implementations of time-division switches: the switch operation is asynchronous, no read gate is required, and an optimal number of delay lines is used. Furthermore, this paper reports the first experimental demonstration of optical space-sorting demultiplexing. 相似文献
130.
借助原位液体透射电镜,我们观察并研究了钯纳米棒溶液环境下的氧化刻蚀的微观行为及机理。通过改变钯纳米棒所处的液体环境,有效地控制了钯纳米棒的氧化刻蚀行为。由于端部具有较高的反应活性,钯纳米棒在氯化铁溶液中的氧化刻蚀会选择沿着轴向进行,具有明显的各向异性。当反应在超薄液层进行时,钯纳米棒的氧化刻蚀会变为准各向同性。这种行为是由于超薄溶液中溶解产物以及氧化物的扩散被抑制,在纳米棒端部选择性发生的氧化刻蚀会受到阻碍。最后,我们发现在钯纳米棒端部选择性沉积金,可以保护纳米棒的端部不受氧化,从而能控制刻蚀沿着钯纳米棒的径向进行。本文的研究结果对贵金属纳米晶的结构参数的精确调控以利于实际应用具有重要的意义。 相似文献