Correlation of processing parameters and in situ temperatures for electron beam irradiated polycarbonate

Temperature measurements were performed for polycarbonate samples under electron beam irradiation for a total dose of 200 kGy at different dose fractionations. The samples were irradiated with a commercial electron beam accelerator and total dose was applied at different number of passes under the beam. Peak temperatures by beam heating obtained during irradiation varied significantly with different amounts of energy deposited per pass. For one-pass irradiation (200 kGy), the peak temperature recorded exceeded the polycarbonate's glass transition temperature.     

电子束辐照与电化学还原联用技术——一种用于煤炭直接液化的新方法

对电子束辐照与电化学联用技术提高煤炭液化率的新型方法进行了研究。利用高能电子束对煤炭样品进行辐照,并通过四氢呋喃萃取出辐照后的可能产物并计算其提取率。实验结果发现,提取产率随着辐照剂量的增加而增加,并得到在氧气气氛下25 kGy的最佳辐照条件。辐照的样品进一步在氢氧化钠电解液中电化学还原液化,并采用元素分析法、傅里叶红外光谱法、阴极极化曲线法、核磁共振法和计时电流法等来检测辐照对煤炭电化学还原的影响。     

Microanalytical investigation of fibre-reinforced ceramic materials

Summary Microanalytical investigations have been made on samples of ceramic fibres (SiC fibres, (Nicalon) C fibre coated with TiN) and fibre-reinforced ceramics (SiC- and glass-matrices). High resolution Auger electron spectroscopy (HRAES), electron probe microanalysis (EPMA) and scanning electron microscopy were employed for these examinations. Analysis was best performed with HRAES on account of its lateral and depth resolution. Some of the problems involved in this technique are discussed e.g. electron beam effects. AES depth profiles of ceramic fibres are reported and compared with the surface analysis of fibres in the composites after being broken in situ.

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Mikroanalytische Untersuchungen faserverstärkter keramischer Werkstoffe

     

Preparation of micro- and nanopatterns of polymer chains grafted onto flexible polymer substrates

In this work a simple novel method for preparing micro- and nanoscale patterns of polymer chains grafted onto flexible polymer substrates is described. A combination of the two techniques of radiation grafting and "grafting-from" has been made. This combination makes it possible to prepare grafted structures having micro- or nanoscale lateral dimensions that are determined by the electron beam or X-ray irradiation patterns used. The height of the grafted features can be controlled by the irradiation dose or such grafting reaction conditions as time, temperature, or monomer concentration. Our first results for nanopatterned samples demonstrate resolution comparable to those of other polymer-based lithography processes.     

Radiation and chemical pretreatment of cellulosic waste

RADIATION AND CHEMICAL PRETREATMENT OF CELLULOSIC WASTE. Combination pretreatment of cellulosic wastes such as corn stalk, cassava bark and peanut husk were studied using chemical and irradiation of electron beam. The effect of 2 % NaOH and irradiation at the doses of 100, 300 and 500 kGy on the cellulosic wastes were evaluated by measurement of the glucose yield in enzymatic hydrolysis. Irradiation was carried out with an electron beam machine EPS-300 (Energy 300 kev, current 50 mA). The result shows that the glucose yield were higher by increasing of dose irradiation and treated with 2 % of NaOH especially in corn stalk. The glucose yield of corn stalk were 20 % in untreated samples and increases to 43 % after treated with electron beam irradiation at the dose of 500 kGy and 2 % NaOH. Cassava bark and peanut husk show the glucose yield are only 3.5, and 2.5% respectively. The effect of E-beam current in enzymatic hydrolysis of corn stalk, and preliminary studied E-beam radiation pretreatment of cassava bark are also reported.     

High-energy electron beam lithography of octadecylphosphonic acid monolayers on aluminum

Monolayers of octadecylphosphonic acid were self-assembled on silicon substrates sputter coated with aluminum. Patterning of the self-assembled monolayer was achieved by high-energy electron (50 kV) illumination using an electron beam lithography tool. The change in chemical composition of the exposed monolayer was investigated by time-of-flight secondary ion mass spectrometry over an area of 100 x 100 microm2. The electron dose required to fully expose the SAM was found to be about 6 mC/cm2. Gratings were exposed with line widths from 10 microm to 100 nm. The resulting patterns were imaged using friction force microscopy. It was found that the minimum line width is limited to ca. 100 nm by the patterning resolution. The pattern resolution achieved, ca. 40 nm, is equal to the grain size of the sputter-coated aluminum layer, and the possibility that the grain size limits the pattern resolution is discussed.     

A study on chemical composition of spices irradiated by electron beam

Quantitative changes in common organic acids and inorganic acids from spices irradiated by electron beam were studied by Dionex-4000i ion chromograph. The results showed that the acids content of either chilli or the five-spice powder⁽³⁾ irradiated with a dose of 9.94 kGy did not undergo significant changes in comparison with the control samples. The flavour composition in the five-spice powder irradiated by electron beam was also determined by Finnigan MAT-8230B gas chromatograph-mass spectrometer, and compared to the results by heating treatment (120°C, 30min). The comparison indicated that the effect of electron beam treatment on flavour composition was less than that of heating.     

Effect of vinyl acetate content and electron beam irradiation on the flame retardancy, mechanical and thermal properties of intumescent flame retardant ethylene-vinyl acetate copolymer

Ethylene vinyl acetate copolymer (EVA) flame retarded by ammonium polyphosphate (APP) and pentaerythritol (PER) was cross-linked by electron beam irradiation. The effects of vinyl acetate content and electron beam irradiation on the flame retardancy, mechanical and thermal properties of EVA composites were investigated. The volatilized products of EVA/APP/PER composites were characterized by thermogravimetric analysis/infrared spectrometry. As VA content increased, the volatilized products increased in the second decomposition step, but decreased in the third decomposition step. For all samples, the increase of irradiation dose could improve both the gel content and the Limit Oxygen Index (LOI, the minimum oxygen concentration by volume for maintaining the burning of a material) values of irradiated composites. The mechanical and thermal properties of the irradiated EVA composites were also evidently improved at appropriate irradiation dose as compared with those of unirradiated EVA composites, whereas these properties decrease at higher irradiation dose because of the electron beam irradiation-induced oxidative degradation or chain scission.     

Sheep Wool Humidity under Electron Irradiation Affects Wool Sorptivity towards Co(II) Ions

The effect of humidity on sheep wool during irradiation by an accelerated electron beam was examined. Each of the samples with 10%, 53%, and 97% relative humidity (RH) absorbed a dose of 0, 109, and 257 kGy, respectively. After being freely kept in common laboratory conditions, the samples were subjected to batch Co(II) sorption experiments monitored with VIS spectrometry for different lapses from electron beam exposure. Along with the sorption, FTIR spectral analysis of the wool samples was conducted for cysteic acid and cystine monoxide, and later, the examination was completed, with pH measuring 0.05 molar KCl extract from the wool samples. Besides a relationship to the absorbed dose and lapse, the sorptivity results showed considerable dependence on wool humidity under exposure. When humidity was deficient (10% RH), the sorptivity was lower due to limited transformation of cystine monoxide to cysteic acid. The wool pre-conditioned at 53% RH, which is the humidity close to common environmental conditions, demonstrated the best Co(II) sorptivity in any case. This finding enables the elimination of pre-exposure wool conditioning in practice. Under excessive humidity of 97% RH and enough high dose of 257 kGy, radiolysis of water occurred, deteriorating the sorptivity. Each wool humidity, dose, and lapse showed a particular scenario. The time and humidity variations in the sorptivity for the non-irradiated sample were a little surprising; despite the absence of electron irradiation, relevant results indicated a strong sensitivity to pre-condition humidity and lapse from the start of the monitoring.     

Orientation Imaging Microscopy for the Transmission Electron Microscope

The resolution limit of Orientation Imaging Microscopy in the Scanning Electron Microscope is between 20 nA and 80 nA depending on the basic resolution/beam current performance of the SEM, the sample atomic number and the level of residual strain within it. The newer technique of orientation imaging in the transmission electron microscope, TEM, improves on this resolution limit by a factor of five to ten. The new technique is based on a novel procedure for determining the crystallography of separate small volumes in the sample by examination of a large series of dark field images. Each image is recorded for a different diffraction condition. This is achieved by using a computer to direct the electron beam onto the same area of the sample so that it covers all directions within a cone of semi-apex angle 3 degrees. Analysis of the intensity of the same point in each of the dark field images permits reconstruction of a diffraction pattern for that point providing the data to calculate its crystal orientation. The process is repeated for each point in the image. The Orientation Image Micrograph is constructed from the orientations so determined. The technique is shown to be capable of producing orientation micrographs of high spatial resolution for unstrained samples. For highly strained samples difficulties are encountered in accurately indexing the complicated diffraction patterns that are observed. Methods to improve the indexing procedures involve determining the sub-cell structure first from a comparison of patterns from adjacent pixels and then summing all patterns belonging to a single sub-cell. The resultant improvement in pattern quality permits more reliable determination of orientation. Examples of this procedure are taken from studies of deformed aluminum.     

Electron radiation damage of MCM-41 and related materials.

The article compares the relative stability of MCM-41 and related mesoporous materials in electron beam at an accelerating voltage of 100-300 kV. The work encountered in electron microscopy presents a comparison with similar research that has been carried out on nonporous and microporous silicates, especially alpha-quartz and zeolite Y. The trends in stability are analyzed, classifying the effects of sample preparation, organic and inorganic moieties, and electron accelerating voltage on beam stability. A higher synthesis temperature, the use of an acid catalyst in the synthesis, and the presence of additional organic or inorganic material within the channels were all found to stabilize these materials. The dose required to completely disrupt the structure increased with accelerating voltage for nearly all samples, suggesting a primarily radiolytic damage mechanism. The exception, MCM-41 containing nanometer-sized titania particles in its channels, was found to be almost insensitive to accelerating voltage.     

Spatial resolution limitation in Auger microanalysis of compounds

The width of the resolved gap between the features of Auger images was calculated by Rayleigh criterion. When the threshold contrast is provided, this width is almost independent of the examined specimen nature and is defined only by probing electron beam diameter. The relation between the irradiation dose, contrast and spatial resolution is deduced. The flexible dependence allowing to evaluate both the real and maximum attainable spatial resolution of Auger images is obtained.     

Optimization of electron beam crosslinking of wire and cable insulation

The computer simulations based on Monte Carlo (MC) method and the ModeCEB software were carried out in connection with electron beam (EB) radiation set-up for crosslinking of electric wire and cable insulation. The theoretical predictions for absorbed dose distribution in irradiated electric insulation induced by scanned EB were compared to the experimental results of irradiation that was carried out in the experimental set-up based on ILU 6 electron accelerator with electron energy 0.5–2.0 MeV.The computer simulation of the dose distributions in two-sided irradiation system by a scanned electron beam in multilayer circular objects was performed for various process parameters, namely electric wire and cable geometry (thickness of insulation layers and copper wire diameter), type of polymer insulation, electron energy, energy spread and geometry of electron beam, electric wire and cable layout in irradiation zone. The geometry of electron beam distribution in the irradiation zone was measured using CTA and PVC foil dosimeters for available electron energy range. The temperature rise of the irradiated electric wire and irradiation homogeneity were evaluated for different experimental conditions to optimize technological process parameters. The results of computer simulation are consistent with the experimental data of dose distribution evaluated by gel-fraction measurements. Such conformity indicates that ModeCEB computer simulation is reliable and sufficient for optimization absorbed dose distribution in the multi-layer circular objects irradiated with scanned electron beams.     

Electron beam coater for reduction of charging in ice-embedded biological specimens using Ti(88)Si(12) alloy.

Biological macromolecules embedded in vitreous ice are known to suffer from charging while being imaged in an electron transmission cryomicroscope. We developed an electron beam coater that deposits conductive films onto the surface of frozen-hydrated specimens. The conductive films help to dissipate charge during electron irradiation of poorly conductive ice-embedded biological samples. We observed significant reduction in charging of ice-embedded catalase crystals suspended over holes in a holey carbon film after coating them with a 30-A-thick layer of an amorphous alloy, Ti(88)Si(12). Images of the crystals after coating showed diffraction spots of up to 3 A resolution.     

Mechanical properties and heat shrinkability of electron beam crosslinked polyethylene–octene copolymer

The mechanical properties and heat shrinkability of electron beam crosslinked polyethylene–octene copolymer were studied. It was found that gel content increases with increased radiation dose. The analysis of results by the Charlesby–Pinner equation revealed that crosslinking was dominant over chain scission upon irradiation. Formation of a crosslinked structure in the electron beam irradiated sample was confirmed by the presence of a plateau of dynamic storage modulus above the melting point of the polymer. Wide-angle X-ray diffraction revealed that there was little change in crystallinity for the irradiated samples, indicating that radiation crosslinking occurs in the amorphous region of the polymer. The tensile modulus increases, whereas the elongation at break decreases with increased radiation dose. The heat shrinkability of the material increased with an increased radiation dose because the radiation-induced crosslinks serve as memory points during the shrinking process.     

Automated technological radiation installation for sterilization of medical goods

Last years most of the developed countries are using radiation method based on electron accelerators for sterilization of medical goods as mostly safe and ecologically pure from all known methods. The report describes in details the automated installation for sterilization of single-use syringes working in the city of Izhevsk, Russia. The syringes are irradiated from two sides inside the packs containing 250 units each. The packs are automatically turned on the inclined part of the conveyor under influence of their own weight. The syringes are posed vertically along the beam fall. The ration of maximal absorbed dose to minimal is 1.4. The productive rate of installation is no less 100 000 syringes per hour. The installation is based on the linear pulse electron accelerator ILU-6. It is the single cavity machine with electron energy up to 2.5 MeV and average beam power up to 20 kW. The pulse nature of the current and automatic control system permit to vary the absorbed dose in great range. The electron energy, beam current, pulse repetition rate, beam position in the extracted window and transportation of the treated products are computer controlled.     

Electron beam irradiation effects on poly(ethylene terephthalate)

Changes in poly(ethylene terephthalate) subjected to electron beam irradiation at doses up to 15 MGy and dose rate of 1.65 MGy/h, were investigated by differential scanning calorimetry, molecular weight measurement, X-ray photoelectron spectroscopy, and scanning electron microscopy. Irradiated samples showed a decrease of molecular weight with a minimum at 5 MGy, which is attributed to chain scission of the macromolecules and then an increase at further doses due to branching and some degradation effect. Irradiation in air is not an important factor because the high dose rate of irradiation inhibits oxygen diffusion in the samples.     

Fluorine in Shark Teeth: Its Direct Atomic‐Resolution Imaging and Strengthening Function

Atomic‐resolution imaging of beam‐sensitive biominerals is extremely challenging, owing to their fairly complex structures and the damage caused by electron irradiation. Herein, we overcome these difficulties by performing aberration‐corrected electron microscopy with low‐dose imaging techniques, and report the successful direct atomic‐resolution imaging of every individual atomic column in the complex fluorapatite structure of shark tooth enameloid, which can be of paramount importance for teeth in general. We demonstrate that every individual atomic column in shark tooth enameloid can be spatially resolved, and has a complex fluorapatite structure. Furthermore, ab initio calculations show that fluorine atoms can be covalently bound to the surrounding calcium atoms, which improves understanding of their caries‐reducing effects in shark teeth.     

The effect of high-energy electron beam irradiation and content of ATH upon mechanical and thermal properties of EVA copolymer

Mechanical and thermal properties of ethylene vinyl acetate (EVA) mixed with various amounts of alumina trihydrate (ATH), irradiated with 5 MeV electron beam at dose range varied from 38 to 190 kGy, have been studied. A small amount (1%) of triallyl cyanurate has been used as a radiation sensitizer. It has been found that (i) EVA samples with various contents of ATH are crosslinked, (ii) crosslinking increases with irradiation dose, (iii) the mechanical properties of samples improve by irradiation and (iv) decomposition of samples takes place at two stages and due to irradiation, decomposition temperatures shift to higher values. These studies were carried out in order to obtain a suitable compound for wire and cable insulation.     

Application of electron beam irradiation combined to conventional treatment to treat industrial effluents

A preliminary study to combine electron beam irradiation process with biological treatment was carried out. Experiments were conducted using samples from a governmental wastewater treatment plant (WTP) that receives about 20% of industrial wastewater, with the objective of destroying the refractory organic pollutants and to obtain a better performance of this plant. Samples from five different steps of WTP were collected and irradiated in the electron beam accelerator in a batch system with 5.0, 10.0 and 20.0 kGy doses. The main results showed a removal of 99% of all organic compound analysed in the industrial receiver unit (IRU) effluent and in the coarse bar screen (CBS) effluent with a 20 kGy dose, and for the medium bar screen (MBS) and primary sedimentation (PS) effluent a 10 kGy dose was sufficient. In the case of final effluent (FE), a dose of 5 kGy removed the remaining organic compounds and dyes present after biological treatment.