Biochemical composition and photosynthetic activity of Pongamia pinnata（L.） Pierre in response to acute 60Co γ-irradiation

To elucidate the potential and sensitivity of cirradiation in Pongamia pinnata,the present study has been done by irradiating the air-dried seeds to differentγ-irradiation doses(100 Gy,200 Gy,400 Gy and 600 Gy),using 60Co source.Significant increase(p≤0.05)in the germination,growth,and vigor was recorded under the100 Gy treatment than the control set.The chlorophylla and total chlorophyll content(mgg-1 FW)in the leaves of P.pinnata showed a significant decrease under the higher irradiation treatments(200 Gy,400 Gy and 600 Gy).In contrast,chlorophyllb showed a radio-resistance up to 200 Gy dose,and above which its concentration declined significantly(p≤0.05).Photosynthetic rate,stomatal conductance,intercellular CO2 concentration,and transpiration rate were stimulated by 100 Gy irradiation treatment and the higher doses inhibited these parameters.Antioxidant activity in the leaves of P.pinnata tended to increase after irradiation in a dose-dependent manner.All the plants under different treatments ofγ-irradiation showed stimulation in production of proline,flavonoid,and phenolic content in comparision to the control.The findings of the present study showed thatγ-irradiation treatment stimulates the secondary metabolite production(proline,flavonoid and phenolic)and favours faster growth of P.pinnata.

Radiation-induced reduction of chromium(VI) in aqueous solution by γ-irradiation in a laboratory-scale

Radiation-induced reduction of chromium（Ⅵ）（Cr（Ⅵ） by ,γ-irradiation was studied with an initial concentration of 42 mg/L in aqueous solutions. Several factors which might affect the reduction of Cr（Ⅵ） to Cr（Ⅲ） were examined, pH of aqueous solution affects the reduction efficiency significantly. Acidic condition of aqueous solution accelerates the process. At pH 2, a reduction of 86.2% was achieved with the absorbed dose of 15 kGy, while, with the same dose, at pH 5 and 7, the reduction ofCr （Ⅵ） were only 36.3% and 22.2%, respectively. Ethanol （0.1% in V：V） and sodium carbonate （1 mmol/L） were added into the solution respectively as relatively non-toxic hydroxyl radical scavengers. Reduction rate increased greatly in the presence of ethanol at each pH. Reduction efficiency of Cr（Ⅵ） was enhanced in neutral condition with the addition of sodium carbonate, however, no enhancement was found in acidic condition. The reduction of Cr（Ⅵ） was restrained when the solution was saturated with oxygen; however, the restraint was not significant.

EFFECT OF γ-IRRADIATION ON CuZnAl SHAPE MEMORY ALLOY

Effect of γ-irradiation on the shape memory alloy CuZnAl has been studied by the techniques of TEM,positron annihilation etc..The martensitic transformation temperature of the alloy increases obviously ofter γ-irradiation at a dose of 2×10~7 Gy but not for a dose of 1× 10~7 Gy.The shape memory effect in both irradiated alloys remains unaffected.

Efficient Extraction of Tea Saponin from Tea Seed Meals by ^(60)Coγ-Irradiation

In order to simplify the extraction process of tea saponin and improve its extraction rate,tea seed meals was taken as materials to explore effects of ^(60)Coγ-irradiation and H_(2)O_(2) on the extraction rate of tea saponin.The results showed that the optimal crude extract condition of tea saponin was 6%H_(2)O_(2) and an irradiation dose of 5 kGy,the extraction rate was 46.4%.However,when the irradiation dose and the H_(2)O_(2) concentration continued to increase,the extraction rate of tea saponin decreased.After flocculate extraction,the tea saponin content increased from 40.80%to 48.32%.Foaming property test results showed that the higher the tea saponin content in the solution was,the higher the foaming height will be,and the foam had a certain stability.This work provided a new method for the extraction of natural products,usingγ-ray irradiation and H_(2)O_(2) pretreatment to improve the extraction rate,and this was of great significance for industrial extraction.

Stability of isoHex-BTP/SiO_2-P adsorbent against acidic hydrolysis and γ-irradiation

Separation of trivalent minor actinides(MA(ⅡI): Am(ⅡI), Cm(ⅡI)) from fission products(FP) in high-level liquid waste(HLLW) is an important task in advanced nuclear-fuel reprocessing systems. For this purpose, an advanced aqueous partitioning process based on extraction chromatography method was studied. Because R-BTP extractants(R-BTP: 2,6-bis(5,6-dialkyl-1,2,4-triazin-3-yl)pyridine, R = alkyl group) exhibit high selectivity for MA(ⅡI) over trivalent rare-earth elements(RE(ⅡI)), a novel adsorbent isoHex-BTP/SiO2-P was prepared by impregnating isoHex-BTP extractant into the macroporous SiO2-P support with a mean diameter of 60 μm. The stability of isoHex-BTP/SiO2-P against nitric acid and γ-irradiation was investigated. It was found that isoHex-BTP/SiO2-P adsorbent shows good adsorption affinity to Dy(ⅡI). The hydrolytic and radiolytic stability of isoHex-BTP/SiO2-P adsorbent in 0.01 mol/L HNO3 was fairly promising. However, the adsorption amount Q of Dy(ⅡI) decreased dramatically in 3 mol/L HNO3 with the increase of the absorbed dose and became nearly zero at the absorbed dose over 46 kGy. These results suggest that with the synergetic effect of radiation and acidic hydrolysis, the adsorbent instantly loses its efficacy.

Development of Magnetic Compound Fluid Rubber Sensor for Practical Usage on γ-Irradiation and Energy Harvesting for Broad-Band Electromagnetic Waves

We have performed sequential studies on new types of soft rubber for their application as artificial skin in robots and haptic sensors. Based on a proposed electrolytic polymerization method and novel adhesion technique for rubber and a metal that utilizes a metal complex hydrate, we have developed an MCF rubber sensor. This sensor uses a magnetic compound fluid (MCF), natural rubber (NR-latex) or chloroprene rubber latex (CR-latex), and requires the application of a magnetic field. The potential application of the developed sensor in various engineering scenarios and our daily lives is significant. In this regard, we investigated the effects of γ-irradiation, infrared radiation, microwaves, and a thermal source on the MCF rubber sensor. We established that the MCF rubber is effective enough to be used for power generation of broadband electro-magnetic waves from γ-rays to microwaves, including the range of the solar spectrum, which is the typical characteristic obtained in the present investigation. The remarkable attribute is that the MCF rubber sensor dose is not degraded by γ-irradiation. We also demonstrated the effectiveness of the MCF rubber sensor in energy harvesting.

The Influence of <i>γ</i>-Irradiation on Thermoemf and Heat Conduction of Ln_0.01Sn_0.99Se (Ln - Pr, Tb, Er) Monocrystals

Monocrystals are synthesized and grown according to Bridgman-Stockbarger method, and the influence of rare earth elements (REE) as well as of γ-irradiation on electrophysical properties of (SnSe)1-x - (SnSe)x (Ln - Pr, Tb, Er) alloy system is investigated. During transition from SnSe to (SnSe)1-x - (SnSe)x solid solutions, a partial compensation of charge carriers occurs and additional scattering centres appear. At low temperatures T after irradiation with γ-quanta, thermoemf in samples of p-type conduction becomes higher and decreases in those of n-type conduction. In addition, under the influence of γ-rays radiation, defects come into being causing a decrease in lattice heat conduction and a rise in electron heat conduction. REE impurities are supposed to be positioned among the points of crystal lattice during irradiation with γ-quanta and, moreover, Frenkel defects are formed.

Effects of γ-irradiation and Deformation Temperature on Tensile Properties of Pb-2 mass% Sb Alloy

Effects ofγ-irradiation and deformation temperature（T）on the tensile properties of Pb-2mass% Sb alloys were studied.The samples were annealed at 458 Kfor 2hin air,then water quenched after they wereγ-irradiated（the different doses were 0.5,1.0,1.5,and 2.0 MGy）.The tensile properties were performed using stress-strain measurements at a constant strain rate（1.2×10^（-3） s^（-1））and at different T（303-393K）.It was found that at constant dose,the fracture stress（σF）decreases while the fracture strain（εF）increases as Tincreases.At particular T,σFincreases whileεFdecreases with increasing dose.The strain-hardening exponent（n）,which is the slope of the relation between ln（σ）and ln（ε）of the parabolic part of the stress-strain curve,was determined and its values increase as Tincreases and decrease as the dose increases.The value of the activation energy increases as the dose increases from 0.07 eV for un-irradiated sample to 0.1eV for the 2 MGy-irradiated sample.These values are in accordance with that needed for dislocation movement and ordering process.An interpretation of the results was given,based on the creation of point and line defects due toγ-irradiation,and that results in a distribution of beta phase（Sb-phase）,leading to a difficulty in the movement of dislocations,so there is an increase in alloy hardness.

CHARACTERIZATION OF γ-IRRADIATED CRYSTALLINE POLYMERS Ⅱ ISOTHERMAL CRYSTALLIZATION KINETICS OF γ-RADIATION INDUCED CROSSLINKED POLYAMIDE 1010

Polyamide 1010 is a γ-radiation crosslinkable polymer. After irradiation, it is possible to raise its service temperature up to 240℃ . Network formation greatly changes the crystallization behaviour of the polymer. In the present work, DSC was used to examine its isothermal crystallization kinetics. It is found that in addition to the necessity of more undercooling and the lowering of crystallization rate, the primary crystallization stage of the irradiated polymer is shortened. This effect is more evident with increasing radiation dose and content of enhanced difunctionai erosslinking agent. However, the crystallization mechanism of the primary stage is not changed as evidenced by the constancy of Avrami exponent. The lamella end surface free energy σ_e calculated according to Hoffman's equation is very sensitive to γ-radiation. It increases abruptly in 2—3 fold even though the radiation dose is not high enough. The origin of this phenomenon may be accounted for in terms of network structure of the polymer.

Utilizing the γ-Irradiated Sodium Alginate as a Plant Growth Promoter for Enhancing the Growth,Physiological Activities,and Alkaloids Production in Catharanthus roseus L.

Sodium alginate is a polysaccharide that is largely obtained from the brown algae （Sargassum sp.）.It has been used as a wonderful growth promoting substance in its depolymerized form for various plants.The aim of this study was to find out the effects of various concentrations of γ-irradiated sodium alginate （ISA）,viz.,deionized water （control,T0）,20 （T1）,40 （T2）,60 （T3）,80 （T4）,and 100 ppm （T5） on the agricultural performance of Catharanthus roseus L.（Rosea） in terms of growth attributes,photosynthesis,physiological activities,and alkaloid production.The present work revealed that ISA applied as leaf-sprays at concentrations from 20 to 100 ppm might improve growth,photosynthesis,physiological activities,and alkaloid production in C.roseus L.significantly.Of the various ISA concentrations,80 ppm proved to be the best one compared to other concentrations applied.

Use of gamma-irradiation pretreatment for enhancement of anaerobic digestibility of sewage sludge

The effects of γ-irradiation pretreatment on anaerobic digestibility of sewage sludge was investigated in this paper.Parameters like solid components,soluble components,and biogas production of anaerobic digestion experiment for sewage sludge were measured.The values of these parameters were compared before and after γ-irradiation pretreatment.Total solid(TS),volatile solid(VS),suspended solid(SS),volatile suspended solid(VSS),and average floc size of samples decreased after cirradiation treatment.Besides,floc size distribution of sewage sludge shifted from 80–100 mm to 0–40 mm after γ-irradiation treatment at the doses from 0 to 30 kGy,which indicated the disintegration of sewage sludge.Moreover,microbe cells of sewage sludge were ruptured by γ-irradiation treatment,which resulted in the release of cytoplasm and increase of soluble chemical oxygen demand(SCOD).Both sludge disintegration and microbe cells rupture enhanced the subsequent anaerobic digestion process,which was demonstrated by the increase of accumulated biogas production.Compared with digesters fed with none irradiated sludge,the accumulated biogas production increased 44,98,and 178 mL for digesters fed sludge irradiated at 2.48,6.51,and 11.24 kGy,respectively.The results indicated that γ-irradiation pretreatment could effectively enhance anaerobic digestibility of sewage sludge,and correspondingly,could accelerate hydrolysis process,shorten sludge retention time of sludge anaerobic digestion process.

Corrosion behavior of high-level waste container materials Ti and Ti-Pd alloy under long-term gamma irradiation in Beishan groundwater

Titanium and titanium-palladium alloys are important potential materials for nuclear waste container,which will endure both intenseγ-irradiation and groundwater erosion.Therefore,it is very important to investigate the corrosion behavior of the container materials.In this research,the cumulative dose effect of TA8-1 type titanium-palladium alloy(TA8-1)and TA2-type pure titanium(TA2)underγ-irradiation was studied based on the geological disposal of nuclear wastes.The irradiation experiments were performed at room temperature using^(60)Co gamma sources with a 5.0-kGy·h^(-1)intensity for 40,80 or 160 days,respectively.The pH value and conductivity of Beishan groundwater were investigated.The results showed that the pH value changed from alkaline(8.22)to acidic(2.46 for TA8-1 and 2.44 for TA2),while the un-irradiated solution remained alkaline(8.17 for TA8-1 and 8.20 for TA2)after 160 days.With the increase of irradiation dose,the conductivity increases rapidly and then tends to become stable,which indicates that the titanium dioxide corrosion layer formed on the surface of the sample surface effectively prevents further corrosion.Meanwhile,XRD and SEM-EDS analysis results show that the main components of corrosion products are TiO_(2) and TiO.The titanium on the surface of the sample is oxidized,resulting in slight uneven local corrosion.The results show that TA8-1 and TA2 are suitable to be used as candidate materials for high-level waste(HLW)disposal containers due to their excellent performance under long-term and high-dose irradiation corrosion.

Radiation-Chemical Degradation of Oxalic Acid in Water Solutions

Co60 gamma ray radiolysis of aqueous oxalic acid solution （1 × 10-2 M） was investigated within the dose range up to 80 kGy. The value of pH increases from 2.0 to 4.0 and approximately 90% of oxalic acid and its derivatives are degraded at the dose of 80 kGy. Dissolved O2 affects to the degradation of oxalic acid at the initial stage due to total consumption of O2 at the dose of 2 kGy. Formation of CO2 occurs at a higher rate at the initial stage until the dissolved 02 is fully consumed. The kinetic model of oxalic acid degradation in aqueous solution under the gamma irradiation was tested. The suggested mechanism complies with the experimental data both of our own and of that reported earlier.

Low Doses of Ionized Radiation and Hypomagnetic Field Alter Redox Properties of Water and Physiological Characteristics of Seeds of the Highest Plants

The influence of a 40-fold attenuated geomagnetic field and its combined action with low doses of α- and γ-irradiation on the physiological characteristics of seeds of the highest plants and redox properties of water was investigated. It established the reduction of seed germination both under direct and indirect effects due to water action of attenuated geomagnetic field. A negative effect of hypomagnetic field on grown characteristics of seeds under indirect effect via water was decreased by the low doses of γ-irradiation, and was increased by low doses of α-irradiation, i.e. ionized radiation was the dominant factor in their combined action. It was revealed the increasing of the value of the oxidation-reduction potential of water under the influence of low-intensive α-ir-radiation (239Pu), γ-irradiation (137Cs) and also that the magnetic induction attenuated pointing to a natural decline. The increasing of the oxidation-reduction potential value testifies about “the regular decreasing of internal energy of water molecules” and the increasing of its oxidative properties, which, in our opinion, is caused the inhibition of the germination of seeds. It is supposed that namely water is the main component in the effects of studying factors on bio-objects, which acts due to the alterations of the properties and structural content of water.

The Effects of Radiationon Crystal Transformationsof Poly（vinylidenefluoride）

his paper covers the effects of γ-radiation on crystal transformations of Poly-(vinylidene fluoride)before and after drawing as well as during annealing process.The results show that the drawing results in a drastic increase in both crystallinityalong the meridian direction and β-form crystal content for the irradiated samples.When the drawn samples were irradiated under appropriate dose and then annealedat 140℃ , transformation from β-form to a-form was subjected to an inhibition.The transformation mechanisms between the two types of crystals are discussed onthe basis of results of WAXD and DSC.

Delayed plasticity during spherical nanoindentation of an iron-chromium-aluminum alloy:Effect of ferric ion irradiation

Spherical nanoindentation of an iron-chromium-aluminum alloy was conducted to study the effect of ferric-ion(Fe 3+)irradiation on the time-dependent plasticity behavior in the surface layers of this alloy.It was observed that the initiation of plasticity by the appearance of displacement burst or“pop-in”event occurred after a period of waiting time in the apparent elastic regime and that Fe^(3+)irradiation at 360°C and up to∼0.5 displacements per atom could make it happen under the lower applied loads but with a reduced magnitude.Through the experimental data,an activation volume and activation energy were extracted for the delayed plasticity.The results show that Fe^(3+)-irradiation significantly reduced its acti-vation volume from∼3.05 b 3 to∼1.75 b 3(where b=Burgers vector),but slightly increased its activation energy from∼0.65 to∼0.71 eV.On the other hand,high-resolution scanning transmission electron mi-croscopy observations reveal that the irradiation at the elevated temperature created interstitial atom pair onto the(100)habit plane that can serve as the nucleation site of a100dislocation loop while elim-inating the pre-existing dislocations.Consequently,it is indicated that heterogeneous nucleation of the dislocation loop was predominant in the delayed plasticity initiation of this alloy and that the nucleation of the interstitial-type dislocation loop was involved due to Fe^(3+)-irradiation.

CHARACTERIZATION OF γ-RADIATION CROSSLINKED CRYSTALLINE POLYMERS BY CRYSTALLIZATION TEMPERATURE

The effect of gamma-radlatlon on plain crystalline polymers and crystalline polymers containing different amounts of difunctional monomer both in vacuum and in air at room temperature has been investigated with DSC. It was found that the crystallization temperature T_c of crosslinked sample measured on DSC at a constant cooling rate decreases with increasing radiation dose. The difference between T_c before and after crosslinking (T_(c_0)-T_(c_R)) is linearly related to the radiation dose for plain polymer. Based on the Charlesby-Pinner equation, an expression has been derived:where S is the sol fraction, A and B are constants. Since there is evidence that T_c is relative to S or crosslinking desity only and independent of the radiation crosslinking, the equation is also applicable to the enhanced gamma-radiation crosslinking of the polymer and can be used to evaluate the instantaneous G(c.1.)_R value of nonrandom crosslinking system. Therefore, determination of T_c with DSC offers a convenient approach to the quantitative study of the random and especially nonrandom crosslinking reaction of crystalline polymer.

SPECTRAL CHARACTER AND EFFECT OF γ-RAY IRRADIATION ON THE CRYSTAL OF CaF_2:Ce^(3+)

Ce3+ has only one 4f electron, whose ground levels are 2F5/2 and 2F7/2, and the difference between the two levels is about 2200 cm-1. It is d→f transition and differs from other trivalent RE ions. Its characteristic emissions are two broad-bands resulting from the transitions of d→2F5/2 and d→2F7/2. When Ce3+ ions replace Ca2+ ions, the charge

One-step synthesis of hollow UO2 nanospheres via radiolytic reduction of ammonium uranyl tricarbonate

Black precipitates were successfully obtained by radiolytic reduction of ammonium uranyl tricarbonate in the aqueous solution of HCOONH_4 by one step.TEM,SAED,EDS,and XRD analysis indicated that the precipitates consist of hollow UO2 nanospheres（φ：30-50 nm,wall thickness：8-15 nm,and cavity diameter：10-20 nm）.The effect of HCOONH4 concentration,irradiation time and dose rate on the morphology,and size of nanospheres was investigated.Then,a gas-bubble template mechanism was proposed.

From Two-Dimensional Metal Organic Coordination Networks to Near-Infrared Luminescent PbS Nanoparticle/Layered Polymer Composite Materials

Two-dimensional(2-D)layered metal-organic coordination(lead methacrylate(LDMA))networks have been prepared in aqueous solution under mild conditions and their structure determined by single crystal diffraction.As the ligand used in our experiments is easily polymerized,these metal-organic coordination layers are therefore employed as precursors to fabricate cross-linked polymer layered materials throughγ-irradiated polymerization.The stabilities of the samples are signifi cantly improved afterγ-irradiation.To our knowledge,this is the fi rst time that covalent bonded polymer layered structures have been fabricated without the assistance of added surfactant or template.Such layered polymer materials cannot only act as alternatives to layered inorganic materials in some caustic environments,but also allow the generation of PbS nanoparticles(NPs)without aggregation in the polymer matrix.By exposing the polymer layer to H2S gas at room temperature,uniform PbS nanoparticles with an average size of about 6 nm are generated in situ.In addition,the resulting PbS NPs exhibit near-infrared(NIR)luminescent properties,which suggests the composite materials may be useful as active optical elements at communication wavelengths from 1300 to 1550 nm.