Effect of calcium ions on the irradiation induced inactivation of cellulase

Abstract The activity of cellulase irradiated at various temperatures was examined as a function of irradiation dose. The effect of calcium ions in radiation inactivation of cellulase at irradiation temperature of 30°C was studied by using calcium sulfate. The calcium ions have a protective ability against radiation caused inactivation of cellulase by scavenging species such as OH(-) formed by irradiation of cellulase aqueous solution, in which the effective concentration range of the calcium ions was ～ 10(-3) M. The calcium ions do not act for the heat inactivation of the enzyme and the enzyme hydrolysis of filter paper or chaff as an activator because the calcium ions do not associate with the enzyme to form a calcium ion-enzyme complex.     

Irradiation and heating effects in amethyst crystals from brazil

Abstract

In this work we report optical absorption spectroscopy study of thermal and irradiation effects on samples of amethyst from Minas Gerais and Rio Grande do Sul, Brazil. Three bands were studied: 10500 cm^?1 (k), 18300 cm^?1 (θ) and 28000 cm^?1 (ζ). Thermal and irradiation effects shows that the θ and ζ bands belongs to a same center and the k band to another center. The isothermal decay and irradiation growth of these band reveal a complex kinetics. The optical absorption bands of amethyst from Minas Gerais do not recover the prmitive absorbance after being bleached at 470°C and irradiated. This sample heated at 470°C in highly reducing atmosphere gets a yellow-brown color. The amethyst from Rio Grande do Sul treated at 400°C gets, also, a yellow-brown color. We suggest this color is probalbly due to the formation of Fe₂O₃ submicroscopc segregate crystals due to the diffusion of Fe ions and oxygen vacancies.     

Swift heavy ions-induced degradation on the electrical characteristics of silicon NPN power transistors

ABSTRACT

The pre- and post-irradiation effects on the DC electrical characteristics of 100?MeV Phosphorous (P⁷⁺) and 80?MeV Nitrogen (N⁶⁺) ion-irradiated NPN transistors were studied in the dose range from 600?krad (Si) to 100?Mrad (Si). The different electrical characteristics, such as Gummel characteristics, excess base current (ΔI_B?=?I_B-Post?–?I_B-Pre), current gain (h_FE), damage constant (K) and output characteristics, were measured in situ after ion irradiation. The considerable increase in the base current (I_B) at lower V_BE and slight decrease in the collector current (I_C) at higher V_BE were observed after ion irradiation. The C–V measurements revealed that the doping concentration (N_d) was found decreased, while the built-in potential (V_bi) increased after irradiation. The ion-irradiated results are compared with ⁶⁰Co gamma-irradiated results in the same dose range. The SRIM simulation was performed to understand the range of ions and energy loss in the transistor structure. The SRIM simulation showed that 100?MeV P⁷⁺ and 80?MeV N⁶⁺ ions can easily pass through the active region of transistors by creating ionization and displacement damages in the device structure. The irradiation results showed that ions induce more degradation in the electrical characteristics when compared to ⁶⁰Co gamma radiation at the same dose range.     

Comparative study on low energy ion beam modification of thermoplastic polymers

ABSTRACT

Polycarbonate (PC) and polyethylene terephthalate (PET) thermoplastic polymer films were irradiated by low energy ion beams such as 100 keV Hydrogen (H⁺) ions and 350 keV Nitrogen (N⁺) ions at varied fluence from 1?×?10¹³ ions/cm² to 5?×?10¹⁴ ions/cm². The depth profile concentration of ions was calculated using Stopping and Range of Ions in Matter (SRIM) software code. Fourier Transform Infrared (FTIR) technique shows decrement in the intensity of peaks and disappearance of peaks mainly related to carbonyl stretching at 1770?cm^?1 and C–C stretching at 1500?cm^?1. Scanning electron microscopy (SEM) of irradiated polymers showed the formation of pores. X-ray diffraction (XRD) analysis has showed decrease in the intensity indicating the decrease in crystallinity after irradiation. Mechanical studies revealed that the molecular weight and microhardness decrease with increase in ion fluence due to increase in chain scission. The contact angle increased with increase in ion fluence indicating the hydrophobic nature of polymer after irradiation. Antibiofilm activity test of irradiated films shows resistance to Salmonella typhi (S. typhi) pathogen responsible for typhoid. The study shows that Nitrogen ion induces more damage compared to Hydrogen ions and PC films get more modified than PET films.     

Induced absorption in yttrium aluminium perovskite crystals irradiated by 12C and 235U ions

The present work is devoted to investigation of optical absorption in pure and neodymium-doped YAlO₃ (YAP) single crystals in the spectral range 0.2–1.1 μm induced by the influence of ¹²C ions irradiation with energy 4.50 MeV/u (MeV per nucleon) and a fluence 2 × 10⁹ cm^?2 or of ²³⁵U ion irradiation with energy 9.35 MeV/u and a fluence 5 × 10¹¹ cm^?2. The induced absorption in the case of ¹²C ions irradiation is caused by recharging of point growth defects and impurities under the radiation influence. After irradiation by ²³⁵U ions with fluence 5 × 10¹¹ cm^?2 the strong absorption rise is probably caused by contribution of the lattice destruction as a result of heavy ion bombardment.     

Heavy-ion irradiations of Fe and Fe–Cr model alloys Part 1: Damage evolution in thin-foils at lower doses

The evolution of radiation damage in Fe and Fe–Cr alloys under heavy-ion irradiation was investigated using transmission electron microscopy. Thin foils were irradiated with 100 or 150 keV Fe⁺ and Xe⁺ ions at room temperature (RT) and 300°C. Dynamic observations followed the evolution of damage and the early stages in damage development are reported. Small (2–5 nm) dislocation loops first appeared at doses between 10¹⁶ and 10¹⁷ ions m^?2 in all materials. Loop number densities depended strongly on the foil orientation in pure Fe but not in Fe–Cr alloys. Number densities did not depend strongly on Cr content. For a given material, defect yields were higher for Xe⁺ ions than for Fe⁺ ions, and were higher at RT than at 300°C. Loops with both ?100? and ½?111? Burgers vectors were identified. The proportion of ?100? loops was larger, especially in pure Fe. Dynamic observations showed that: the contrast of some new loops developed over intervals as long as 0.2 s; hopping of ½?111? loops was induced by the ion and electron beams and was pronounced in ultra-pure iron; and many loops were lost during and after ion irradiation by glide to the foil surface. The number of loops retained was strongly dependent on the foil orientation in Fe, but less so in Fe–Cr alloys. This is due to lower loop mobility in Fe–Cr alloys, probably due to pinning by Cr atoms. Reduced loop loss probably explains the higher loop number densities in Fe–Cr alloys compared with pure Fe.     

Effect of N5+ ion irradiation on l-ornithine monohydrochloride single crystals: an organic nonlinear optical material

In this work, the authors have grown good-quality single crystals of l-ornithine monohydrochloride (LOHCL), an organic nonlinear optical material, in the aqueous solution by the slow cooling technique. N⁵⁺ ion irradiation of three different doses (i.e. 1?×?10¹⁶, 5?×?10¹⁶ and 1?×?10¹⁷?ions/cm²) at room temperature was done on the cut and polished crystal specimen of appropriate size from the grown crystal. A detailed study of FT-Raman spectroscopic was carried out to see the effect of irradiation on structure and vibrational modes of the LOHCL crystal. The results revealed that there is no structural modification even at high doses except the variation in peak intensity, which indicates that the grown crystals of LOHCL have good stability and also confirms that the nitrogen ions do not substitute into the crystal lattice. The UV–Vis–near-infrared spectroscopic study was done on all the samples to see the effect of irradiation and various optical parameters such as transmittance (～50–70%), absorption coefficient, energy band gap (～4.75–4.96?eV), extinction coefficient, refractive index (～1.31–1.24), optical permittivity (～1.7–1.6) and susceptibility (～0.7–0.6). The calculated optical parameters were found to vary with change in doses.     

Influence of 120 MeV Si9+ ion irradiation on ZnTe semiconductor thin films

ABSTRACT

ZnTe (Zinc Telluride) is a potential semiconducting material for many optoelectronic devices like solar cells and back contact material for CdTe-based solar cells. In the present study, ZnTe thin films were prepared by thermal evaporation technique and then irradiated with 120?MeV Si⁹⁺ ions at different fluences. These films are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV–Visible spectroscopy techniques. XRD study confirms increased crystallinity and grain growth for post-irradiated ZnTe thin films for fluences, up to 1?×?10¹¹ ions cm^?2. However, the grain size and crystallinity decreased for higher fluence-exposed samples. SEM images confirm the observed structural properties. Modification of the surface morphology of the film due to the ion irradiation with different fluences is studied. Optical band gap of film is decreased from 2.31?eV (pristine) to 2.17?eV after irradiation of Si⁹⁺ ions.     

Neutron radiation on tin anodes of lithium-ion batteries

Abstract

The operating durability of lithium-ion batteries is a principal problem in universe exploration or rescuing work in the nuclear radiation area. In the study, the neutron irradiation experiments were conducted on film-tin electrodes using the radiation dose of 10¹¹, 10¹², 10¹³ and 10¹⁴?n?cm^?2, respectively. The results show that the particle size grows with the increasing radiation does by atomic force microscopy (AFM) and scanning electron microscope (SEM). In addition, the degressive trend of specific capacity of tin anodes after neutron radiations increases with the increasing radiation dose. The fade of electrochemical performances may be attributed to the increasing particle size and defects induced by neutron radiation.     

Migration behaviour of vacancies and damage structure recovery in a Fe-based Fe-Cr-Mn-Cu-Mo multi-component alloy

ABSTRACT

A Fe-based multi-component alloy, 60Fe-12Cr-10Mn-15Cu-3Mo, which presents higher yield stress than typical stainless steels (such as 304, 316, and 340), was used to investigate the thermal stability of irradiation-induced defects. Neutron irradiation was carried out at approximately 323 and 643?K using up to 1.3 × 10^?3 and 4.5 × 10^?4 dpa (displacements per atom), respectively. While no defects were accumulated at the high temperature of 643?K, single vacancies were formed after irradiation at the low temperature of 323?K to 1.3 × 10^?3 dpa, and the vacancies became mobile at 423?K. As a result, vacancy clusters were formed. However, as the annealing temperature increased the size of vacancy clusters decreased. Coincidence Doppler broadening measurements indicated that Cu precipitates were the sites of vacancy cluster formation, and the recovery of vacancy clusters became prominent while annealing the irradiated sample at temperatures higher than 423?K. Recovery of vacancy clusters at 573?K, which was not a high temperature, was also observed even in the sample that was irradiated using 2.5?MeV Fe ions at room temperature to 0.6 dpa at damage peak.     

Anti-biofilm efficiency of 120 MeV Fe+9 SHI-irradiated polyimide film

ABSTRACT

Polyimide (PI) films were irradiated by 120 MeV iron (Fe⁺⁹) ions and variations in its optical, chemical, surface morphology and anti-bacterial properties were studied. UV-Visible spectroscopic results showed the decrease in the optical band gap of PI after irradiation due to the chain scission mainly at the carbonyl group which is corroborated by Fourier Transform Infrared spectroscopic results. The scanning electron microscopic results showed the surface roughening, surface structure broken and micro-porous formation in PI after irradiation. These results are also corroborated by the decrease in contact angle as studied by the contact angle measurement. PI films irradiated by 120 MeV Fe⁺⁹ ions showed increased anti-biofilm efficacy against the human pathogen, Salmonella typhi. In addition to this, the morphological changes were also observed due to the stress of Fe-irradiated PI. Biofilm formation was inhibited ≈ 35% at 1?×?10¹¹ ion/cm² and 80% at 5?×?10¹² ion/cm² in irradiated PI films. Thus, surface modification of PI films help in the inhibition of biofilm formation.

Highlights

1. Polyimide (PI) films were irradiated by 120?MeV Fe⁺⁹ ions.

2. Optical band gap of PI decreased after ion irradiation.

3. Surface roughening and micro-pores formation in PI after ion irradiation.

4. Surface modification of PI films helps in the inhibition of bio-film formation.

     

The atkermal stress component in neutron irradiated mild steel

Abstract

The temperature dependence of the tensile lower yield stress of an annealed aluminium grain size controlled mild steel has been investigated in the range 23–250 °C and at a strain rate of 1.67 × 10^?4 sec^?l before and after neutron irradiation to 2.3 × 10¹⁸ n/cm² (fission). The yield stress of the irradiated steel decreases with increasing temperature due to thermal activation of the radiation damage and is predicted to reach asymptotically that of the unirradiated steel at ～285 °C; the maximum test temperature was below that at which thermal annealing of the damage occurs. This implies that the athermal stress component due to irradiation is zero and hence there is negligible long range interaction between dislocations and radiation-induced defects.     

Optical detection of Yb+ trapped in an rf trap

The fluorescence from Yb⁺ ions trapped in an rf trap was detected by driving the²S_1/2−²P_1/2 transition at 369.52 nm with the radiation generated by sum-frequency mixing of diode-laser and argon-ion-laser radiation. The rf resonance absorption signal as well as the fluorescence signal, when the Yb⁺ ions were continuously irradiated by the resonant uv radiation, faded out with a decay time shorter than the storage time. This observation suggests that the Yb⁺ ions disappeared from the trap with the irradiation of the resonant uv radiation.     

Swift heavy ion provoked structural, optical and electrical properties in SnO2 thin films

SnO₂ thin films grown on glass substrates at 300 ^°C by reactive thermal evaporation and annealed at 600 ^°C were irradiated by 120 MeV Ag⁹⁺ ions. Though irradiation is known to induce lattice disorder and suppression of crystallinity, we observe grain growth at a certain fluence of irradiation. X-ray diffraction (XRD) revealed the crystalline nature of the films. The particle size estimated by Scherrer’s formula for the irradiated films was in the range 10–25 nm. The crystallite size increases with increase in fluence up to 1×10¹² ions?cm^?2, whereas after that the size starts decreasing. Atomic force microscope (AFM) results showed the surface modification of nanostructures for films irradiated with fluences of 1×10¹¹ ions?cm^?2 to 1×10¹³ ions?cm^?2. The UV–visible spectrum showed the band gap of the irradiated films in the range of 3.56 eV–3.95 eV. The resistivity decreases with fluence up to 5×10¹² ions?cm^?2 and starts increasing after that. Rutherford Backscattering (RBS) reveals the composition of the films and sputtering of ions due to irradiation at higher fluence.     

Ion beam mixing of silicon-tin multilayers

Silicon and tin multilayers of total thickness 200 nm have been deposited at room temperature on beryllium and glass plate substrates under high vacuum (<5. 10^?7 mbar). The average atomic tin fraction of the whole layer varied from 0.12 to 0.60. The samples were irradiated at room temperature with Xe⁺ ions of 900 keV energy with fluences of 1.10¹⁵ to 2.10¹⁶ ions. cm^?2. Rutherford backscattering spectrometry (RBS) was used to check overall composition before irradiation. After irradiation, a substitutional Sn site was evidenced by means of¹¹⁹Sn conversion electron Mössbauer spectroscopy (CEMS), the relative population of which depends on composition and irradiation fluence. Transmission electron microscopy (TEM) was used to monitor the evolution of the samples with irradiation fluence. Electrical measurements show semiconductor behaviour of the mixed multilayers with electrical resistivity ranging from 10² to 10^?3 Ω.cm as a function of composition.     

UV-induced photoluminescence and thermally stimulated luminescence of CaSO4:Eu and CaF2:Tb3+ phosphors

Ultraviolet radiation induced changes in photoluminescence (PL) and thermally stimulated luminescence (TSL) of europium activated calcium sulphate (CaSO₄:Eu³⁺, Eu²⁺) and terbium doped calcium fluoride (CaF₂:Tb³⁺) phosphors have been studied. PL measurements suggest conversion of Eu³⁺ to Eu²⁺ on 254 nm irradiation corresponding to charge transfer band of Eu³⁺ ions and reduction of Eu²⁺ ions with 365 nm illumination representing a f–d transition of Eu²⁺ ions. Similar studies carried out on CaF₂:Tb³⁺ phosphor, however, do not show any significant wavelength specific changes. The integrated TSL output appears to be rate-dependent for both phosphors. The wavelength dependent changes in TSL output observed for CaSO₄:Eu phosphor have been correlated with those obtained in PL studies. The changes in TSL and PL characteristics of CaF₂:Tb³⁺ phosphor have been explained on the basis of stabilisation of traps based on matrix specific charge similarities.     

Effect of Helium ion irradiation on the structure,the phase stability,and the microhardness of TiN,TiAlN, and TiAlYN nanostructured coatings

The radiation resistance of nanostructured TiN, TiAlN, and TiAlYN coatings is studied after 500-keV He⁺ ion irradiation in the fluence range 5 × 10¹⁶–3 × 10¹⁷ ions/cm². The radiation-induced changes in the phase composition, the structure, the lattice parameters, the morphology, and the mechanical properties of coatings are investigated. Blistering is found to be absent, and the radiation fluence is shown to affect the strength properties of the thin coatings nonlinearly. A significant decrease in the grain sizes is detected upon ion irradiation, which causes an increase in the microhardness and the radiation resistance of the coatings. The TiN, TiAlN, and TiAlYN coatings are found to be radiation-resistant coatings, which do not undergo serious degradation during high-fluence ion irradiation.     

Annealing of arsenic-and antimony-implanted silicon single crystals using A CW xenon arc lamp

Abstract

Continuous, incoherent light from a xenon arc lamp has been used to anneal radiation damage in <100> silicon single crystals produced by implantation of 30?keV arsenic or antimony ions to doses between 1×10¹⁵ cm^?2 and 1×10¹⁶ cm^?2. The recrystallized layers have been characterized by Rutherford-backscattering spectroscopy, ion-channeling, Transmission Electron Microscopy, and sheet-resistivity measurements.     

Multipurpose implanter for high technology development

To provide basic operations of semiconductor and radiation materials technologies, a multipurpose implanter with intense ion beams was developed at the Institute of Nuclear Physics. The generated beamparameters are as follows: ions are H⁺, O⁺; C⁺; the ion energy is up to 200 keV; the beam current is up to 2 mA; and the implantation mode is continuous. The size of the target to be processed can reach 76 × 76 mm². During the implanter operation, the target chamber vacuum reaches 10^?4 Pa. The entire process of target irradiation is fully automated.     

A description of the laser-induced annealing and diffusion behaviour of implanted silicon crystals

Abstract

It is shown that as a result of the Greenwood-Foreman-Rimmer loop punching mechanism applied for helium bubble growth in nickel implanted with 5 keV He⁺ ions at 273 K, a considerable amount of helium remains outside the bubbles which are visible in a transmission electron microscope (TEM). It is also shown that even when it is assumed that there is an energy barrier with an upper limit equal to the formation energy of a self-interstitial atom, not all implanted helium can be accumulated in the bubbles below the critical dose for blistering.

The experimental observation of bubble growth in a helium pre-implanted nickel specimen during 1 MeV e^? irradiation may demonstrate that indeed a significant amount of helium remains between the bubbles visible in TEM.