Due to a need for security screening instruments capable of detecting explosives and nuclear materials there is growing interest
in neutron generator systems suitable for field use for applications broadly referred to as active neutron interrogation (ANI).
Over the past two years Thermo Electron Corporation has developed a suite of different compact accelerator neutron generator
products specifically designed for ANI field work to meet this demand. These systems incorporate hermetically-sealed particle
accelerator tubes designed to produce fast neutrons using either the deuterium-deuterium (En = 2.5 MeV) or deuterium-tritium (En = 14.1 MeV) fusion reactions. Employing next-generation features including advanced sealed-tube accelerator designs, all-digital
control electronics and innovative housing configurations these systems are suitable for many different uses. A compact system
weighing less than 14 kg (MP 320) with a lifetime exceeding 1000 hours has been developed for portable applications. A system
for fixed installations (P 325) has been developed with an operating life exceeding 4500 hours that incorporates specific
serviceability features for permanent facilities with difficult-to-access shield blocks. For associated particle imaging (API)
investigations a second-generation system (API 120) with an operating life of greater than 1000 hours has been developed for
field use in which a high resolution fiber-optic imaging plate is specially configured to take advantage of a neutron point-source
spot size of ∼2 mm.
Materials of significant inhomogeneity require big samples to be analyzed. With the exception of very few installations worldwide
the near-core neutron irradiation positions are not spacious enough to fulfil this condition. The use of beam geometry activation
analysis (BEAMGAA) has actually turned out to be an alternative as the activities obtained are proportional to the product
of flux and sample mass. In the case of hard photon radiation delivered by the 30 MeV-Linac of BAM, equipped with a programmable
scanner of the electron beam for dose equalization, a nearly uniform distribution could be obtained in a volume of 7 cm×7
cm×2 cm. It is shown that big sample volumes up to 7 cm×7 cm×10 cm can be treated and non-linearities of irradiation can be
perfectly taken into account by the self-adjusting method of consecutive correction factors (COCOFA). Nevertheless, the concept
of “sliced samples” has to be considered when maximum correctness of the analytical results has to be guaranteed. With the
measures described in photon activation analysis a quality level was realized which was not reached hitherto.
Authors:Khairedin Abdalla, Dimitrios Kaziolas and Charalambos Baniotopoulos
The present paper deals with the study of the installation behavior of high-strength bolts under friction. For this purpose an experimental program was conducted to evaluate the energy of these bolts that is dissipated due to tightening and loosening. The total number of tested specimens was 100 bolts furnished to the requirements of AASHTO specification M253M. The turn-of-nut tightening method is applied experimentally to evaluate the pretension and the torque for tightening and loosening of bolts. It is mentioned that a number of 56 bolts has 76 mm length while the rest is of 152 mm. The experimental preloading and the lost torque that overcomes friction are compared with the respective analytical values. It is confirmed that the K-nut factor is affected by the type of lubricant and the length of the bolt. Additionally, most of torque is going to overcome friction. The percentage of tightening and loosening torque for both the analytical and the experimental cases is very close.
Bastianini, F. – Rizzo, A. – Galati, N. – Deza, U. – Nanni, A.: Discontinuous Brillouin strain monitoring of small concrete bridges: Comparison between near-to-surface and „smart” FRP fiber installation techniques. Proceedings of SPIE – The International
The present paper evaluates the results of field experiments conducted during two consecutive growth seasons (2008–2009) to assess the environmental impact of cement dust pollution on foliar physiology (pigments), growth performance and yield of three commonly cultivated vegetable crops, tomato (Lycopersicon esculentum), radish (Raphanus sativus) and knol-khol (Brassica oleracea var. gongyloides) in Kashmir Himalayan valley, India. Two experimental sites (S1, S2) were selected in the vicinity of the cement factory at Khrew, Pulwama (Kashmir) at a distance of 0.5 km (S1) and 2 km (S2) and compared with a dust free control site (S3) located at about 6 km from the factory in a crosswind direction. The data revealed that cement dust had an adverse effect on morphological and biochemical characteristics of the crops. Differential level of crop sensitivity to cement dust was markedly evident. Knol-khol (Brassica oleracea var. gongyloides) reflected a higher degree of tolerance to particulate emissions as compared to tomato (Lycopersicon esculentum) and radish (Raphanus sativus). Photosynthetic pigment analysis showed adverse impact on chlorophyll-a, while chlorophyll-b marginally decreased in the leaves of tomato plants at S1; the effect being non-significant for the other test crops. Carotenoids also exhibited a remarkable reduction due to cement dust impact. The yield of tomato recorded severe losses (12.28–23.95%) as compared to radish (7.46–21.4%), while the effect was non-significant in knol-khol. Other growth and yield related attributes also followed a similar trend; tomato and radish showing remarkable effects in response to cement dust and knol-khol showed the least effect. The soil characteristics indicated significant reduction in available P. Except available N, other variables (pH, conductivity, available K, exchangeable Ca and Mg) recorded higher values in the polluted soils as compared to control. The need for installation of appropriate devices in cement manufacturing factories to combat the emission of dust in ambient environment together with environmental monitoring of agro-ecosystems is stressed.
Authors:Jiunn-Liang Lin, Ai-Yih Wang, Jiunn-Guang Lo and Ren-Shyan Liu
Lipiodol has excellent retainable ability in hepatoma cells. This agent can be labeled with radioisotope (131I) and mixed with tissue adhesive (Histoacryl), and then alttached on the lesion of liver by intrahepatic arterial administration.
In this study, we attempt to obtain the optimal ratio of Lipiodol to Histoacryl and evaluate the consolidation of blood in
vitro and toxicity and biodistribution in vivo. The ratio of131I Lipiodol/Histoacryl mixture (L/H), concentration of heparin and flow rate of blood are varied by simulating the installation
of bloodstream to test the time of consolidation. In addition, the optimal ratios of the L/H mixtures are assessed in vitro
in heparinized human blood. According to those results, Lipiodol and Histoacryl mixed with 1∶1 or 2∶1 ratio have an ideal
time of 13 to 15 seconds in vitro; in addition, 1.2∶1 ratio is an optimal ratio in the biodistribution study. Interestingly,
heparin and acetic acid does not alter the consolidation time, in addition, no variation occurs when varying the flow rate
of blood. The consolidation of L/H mixture with blood is incubated in the 37°C, normal saline bath for 24 hours. No dissociation
of free131I is found. The optimal mixture is also injected into the hepatic artery of the Sprague-Dawley rats carrying for 24 hours.
No dissociation of free131I is found. The optimal mixture is also injected into the hepatic artery of the Sprague-Dawley rats carrying hepatocellular
carcinoma (NIS1 cell line). Radioactive consolidate is well confined in the tumor without evidence of leakage of the mixture
to the lung or distribution of free131I in the thyroid. In conclusion, this mixture has the merits of both irradiation and embolization of the tumor. The131I Lipiodol/Histoacryl mixture (1.2∶1) is a promising alternative for intrahepatic arterial administration to treat hepatic
tumors. Histoacryl can confine the131I and, also, embolize the tumor vessels.
The Comprehensive Nuclear-Test-Ban Treaty (CTBT) plans the installation of an International Monitoring System (IMS) based upon four global networks. Seismic, hydroacoustic and infrasound waves will help detect underground, underwater and atmospheric nuclear tests and will permit their discrimination from natural events. 80 particulate stations will detect radioactive aerosols, this network being completed with a sub-set of 40 stations which will measure rare gases, typically xenon isotopes. 16 IMS laboratories will perform additional analysis mainly by gamma-spectrometry, using the most sensitive methods such as particulate analysis. In order to have the most effective network, modeling was performed by using an inverse method in which the radioactive tracer is transported back from detectors. Examples will be given, regarding the maps of detection probability, background effects of existing xenon or radon, or the decoupling effects. All these tools and means are anticipated to have a complete process of certification, authentication of the data and discrimination capabilities between nuclear test and releases from civilian nuclear industry (reactors, reprocessing plants,). If a State Party identifies events that it feels could be a nuclear explosion, it can ask for clarification and finally it may send a request for an On-Site Inspection. The rights of the State Party and the constraints for the Inspection Team are defined in the Treaty. That leads to limited time, to limited number of inspectors on the site and to precise methods to be authorized. The means and resulting data have to be blinded in order to make sure the confidentiality is observed. Examples of restricting measurements will be given regarding airborne or vehicle mounted spectrometry as well as laboratory analysis. Cooperation with international organizations (WMO, WHO) will be discussed, depending on confidentiality issues.
Authors:D. Das, Sumit Kumar, P. Pathak, B. Tomar and V. Manchanda
Release of long-lived radioactivity to the aquatic bodies from various nuclear fuel cycle related operations is of great environmental
concern in view of their possible migration into biosphere. This migration is significantly influenced by various factors
such as pH, complexing ions present in aquatic environment and sorption of species involving radionuclides on the sediments
around the water bodies. 241/243Am are two major radionuclides which can contribute a great deal to radioactivity for several thousand years. In the present
study, 241Am sorption on natural sediment collected from site near a nuclear installation in India, has been investigated under the
varying conditions of pH (3–10) and ionic strength [I = 0.01–1 M (NaClO4)]. The sorption of Am increased with pH of the aqueous medium [10% (pH 2) to ~100% (pH 10)], which was explained in terms
of the increased negative surface charge on the sediment particles. There was marginal variation in Am(III) sorption with
increased ionic strength (within error limits) of the aqueous medium suggesting inner-sphere complexation/sorption process.
Sediment was characterized for its elemental composition and structural phases using Energy Dispersive X-Ray (SEM-EDX) and
X-Ray Diffraction (XRD) techniques. Zeta-potential measurement at I = 0.1 M (NaClO4) suggested that Point of Zero Charge (pHPZC) was ~2, indicating the presence of silica as major component in the sediment. Kurabtov plot using sorption data as a function
of pH at fixed I = 0.1 M (NaClO4) indicated the presence of multiple Am(III) species present on the surface. Potentiometric titration of the suspension indicated
the presence of mineral oxide like behavior and assuming a generic nature (≡XOH) for all types of surface sites, protonation–deprotonation
constants and total number of sites have been obtained. The sorption data has been modeled using 2-pK Diffuse Double Layer
Surface Complexation Model (DDL-SCM). ≡XOAm2+ has been identified as the main species responsible for the sorption profile.
A kutatás alapja az a feltételezés, hogy a paneles lakótelepek komplex megújítása városépítészeti léptéket követel, melyben az épületek földszintjei, a külső és belső térkapcsolatok újraértelmezése kiemelt fontosságú. A problémakör feltárása a hazai nagypaneles épületek földszintjeinek építészeti kialakítására épül. A cikk a rendelkezésre álló katalógusok alapján egyrészt a talajközeli térhatár (zárt, áttetsző vagy árkádos), másrészt a nyílások (bejárati ajtó, lakásablak, erkély, kapu, kirakat, közös tér ablaka, gépészeti nyílás, átjáró) tipológiáját állítja fel. Ezt a lakó és látogató számára fontos alsó szintet — a tömegterméket, a paneleket tartó, viszonylag sokféle, az adott helyhez is alkalmazkodó fundamentumot — nemcsak a panelházak építési korában, de az elmúlt évtizedek felújításai során is elhanyagolták. A műszaki vagy látványmegoldások alig érintik, így az épített környezetből a használatot terhelő problémák, mint például a rossz szubjektív biztonságérzet, a találkozások tereinek kerülése, az alulhasznosítottság stb. megmaradnak. Az írás a panelföldszintek építészeti megoldásainak összefoglalását adja, rávilágít az ezekből adódó használati problémákra, felhívja a figyelmet a témakör kiemelt kezelésének fontosságára.