Nuclear Track Membranes Research Articles

Direct and indirect determination of track etch parameters after sequential UV-C exposure and etching for two swift heavy ions in PADC: Production of rocket-shaped tracks

The present work aimed to study the effect of single-sided UV-C successive exposures and sequential chemical etching on the different track parameters of bulk etch rate, Vb, detector diameter, D, detector length, L, track etch rate, Vt, detection sensitivity, and etched track shape. For this, PADC detectors initially irradiated with high energy-long range ions of 7 GeV Si and 17.48 GeV Ni were used. Fission fragment irradiations were also performed before UV-C exposure to determine the PADC bulk etch rate in exposed and non-exposed UV-C sides. Track parameters of bulk etch rate, Vb, detector diameter, D, detector length, L, track etch rate, Vt, and corresponding sensitivity were determined and compared on both sides. The relative differences between the track parameters on both sides are thus determined. It was found that exposure of PADC detectors to sequential UV-C followed by etching gives a strong increase in the two etching rates, Vb and Vt. Sensitivity measurements indicate that the rate of increase of Vb is greater than that of Vt. Track parameters data by direct track cone length and indirect track diameter versus depth evidence the existence of two regions under the polymer surface. These two regions were attributed to the polymer crosslinking and degradation processes resulting from exposure to UV-C. Region 1 and Region 2 have different etching rates. Region 1 has a constant rate, while Region 2 has an increasing rate as it goes deeper. Sequential UV-C followed by etching makes it possible to generate unusual rocket-shaped (or amphora-shaped) tracks. One possible application of the described technique is the production of nuclear track membranes.

Identification and harmfulness analysis of solid particles contained in medical injections and their removal by nuclear track membranes

Summary Two types of cascade nuclear track filters have been developed: (1) cascade filter made of polypropylene (PP) fiber membrane as preliminary filter and nuclear track membrane (NTM) as terminal filter; (2) Nylon tortuous-pore membrane as preliminary filter and NTM as terminal filter. Removal of solid particles by the cascade filters has been investigated. The solid particles studied include glass shards from broken ampoules and rubber fragments from rubber covers (plugs) of medical bottles. When an ampoule containing medicine is broken by emery wheel and by hands, large number of glass shards are produced and fall into the medicine. When a rubber cover is punctured by syringe needle, large number of rubber fragments are produced by friction between rubber and needle. The investigation shows that fiber or tortuous membranes alone usually cannot completely remove the microscopic particles due to existence of large gaps in the structure of the two common membranes. Nuclear track membranes alone and their cascade filters are superior to remove all solid particles bigger than the pore size of the track membrane. Removal efficiency for solid particles and flow rate of injections through the cascade filters have been calibrated and shown that both features above fulfill the requirements of Chinese regulations. The two types of cascade filters have been accepted for use in Chinese hospitals.

Applications of Nuclear Track Membranes to Filtration of Medical Injections and Various Transfusions to Remove Solid Particles

Nuclear track membranes produced by China Institute of Atomic Energy (CIAE) in Beijing, China, and the Joint Institute for Nuclear Research (JINR) in Dubna, Russia have been used in the studies of filtration of medical injections and various transfusion liquid medicine to remove solid particles from the medicine. It shows that the filtration devices made of nuclear track membranes are superior to that made of any other types of membranes. Experiments have demonstrated that the removal efficiencies for solid particles with diameters 5μm can reach over 95% and the flow rate is high enough for use in medical injection and transfusion. The reproducibility of removal efficiencies and flow rate of the new devices are satisfactory to the use in hospitals. Chinese authority in medicine has approved the new devices for use in Chinese hospitals.

Potential use of nuclear track membranes in ophthalmology

Potential use of a nuclear track-etched membrane as a semipermeable membrane for fluid transport and maintenance of the cornea in a slightly dehydrated state for its transparency has been studied. The track membrane TOMTREK based on polyethylene terephthalate (PET) with a pore diameter of 0.4 μm and a density of 5 × 106 pore/cm2 has been used in the experiments. The pores have been formed by bombarding the polymer PET with 41.5-MeV 40Ar8+ ions. After bombardment, the membrane was subjected to chemical treatment in an alkali solution. Contact angle θ on the track membrane surface has been measured using the sessile drop method. Disks of a 10 mm diameter have been cut from plasma-treated membrane samples. An appropriate shape has been imparted to the model by incising and sealing the disk edges.

Glucose determination using a re-usable enzyme-modified ion track membrane sensor

A novel concept for a glucose biosensor based on the enzyme glucose oxidase covalently linked to nanopores of etched nuclear track membranes is presented. This device can be used to detect physiologically relevant glucose concentrations between 10μM and 1M. The sensitive catalytic sensor can be made re-usable due to the production of diffusible products from the oxidative biomolecular recognition event. We have demonstrated both the simplicity with which this sensor can be produced and the stability of the enzyme embedded in the nanopores. We strongly believe that the approach could be expanded for different enzymes and variable configurations of sensing and catalysis using membranes with nanopores for biocatalysis and enrichment of substrates and products. This is the first time that such devices are being used for biocatalytic transformations.

Study on filtration properties of nuclear track membrane and its blocking effect

The study of filtration properties of nuclear track membranes for removing the standard insoluble particles from liquid and its flux has been carried out. Furthermore, the blocking effect of micro-pore and the membrane polluted correlation factor will be presented in the paper in detail.

Submicroscopic pores grafted using the residual sites produced by swift heavy ions

To produce nuclear track membranes (NTM) with submicroscopic pores poly(vinylidene difluoride) (PVDF) foils were irradiated with Cl, Ag and Pb ions. Then they were chemically etched for different times and grafted with acrylic acid. The grafting yields were determined by weight measurements as a function of ion fluence, etching time and also analysed using Fourier transform infrared spectroscopy. Both measurements suggest that the acrylic acid was grafted on the pore wall of the NTM using the active sites left by the ion beam.

Swift heavy ion induced graft polymerization in track etched membranes’ submicroscopic pores

Cl or Pb irradiated foils of poly(vinylidene fluoride) (PVDF) were chemically etched to produce nuclear track membranes (NTM) with submicroscopic pores. The NTM were grafted with styrene using the remaining active sites produced by the heavy ion beams. Experimental curves of grafting yield were measured by weight difference as a function of ion fluence and etching time. As the etching time was increased from 0 to 30min a decrease of the grafting yield was observed. Grafted foils were also analysed by Fourier transform infrared spectroscopy (FTIR). Both measurements suggest that the styrene was grafted on the pore wall of the NTM using the active sites left by the ion beam.

Spatial Overlapping of Holes in Nuclear-Track Membranes with Different Angular Distributions

The results of Monte Carlo calculations on the relative number of spatially overlapping holes Wover in track membranes, depending on porosity P for possible angular distributions of ion incidence (pore orientation) are presented. The values of the relative number of overlapping pores in the bulk, Wm (m = 2, 3, ..., 10), were calculated and the relative hole overlap areas were determined. The choice of the most effective angular distributions for the manufacture of track membranes is discussed.

Hole Overlapping Statistics in Reactor Nuclear Track Membranes

Distributions of nuclear holes (cylindrical channels of an identical diameter) in reactor track membranes were studied by computer simulation taking into account the angular spread of an ion beam. The factors of angular decrease in the number of multiple-hole channels and their dependence on the overlap multiplicity and membrane porosity P at P = 0.01–0.30 and hole multiplicity of m < 4 were obtained. The simulation results were compared with predictions made using analytical models.

A Statistical Model for Hole Distribution on the Nuclear-Track Membrane Surface

A statistical model for analysis of overlapping nuclear pores (ring holes of equal diameter) on the flat surface of nuclear track membranes was developed. Statistical distribution of the probability of occurrence of double and triple pores were obtained for medium-porosity (below 0.5) membranes with allowance for configuration forms (for triplets). The results obtained by the analytical procedure are compared with computer simulation data.

Radiation grafting of NIPAAm on PVDF nuclear track membranes

Polymer surface modifications are obtained by the application of radiation treatments and other physico-chemical methods: fragment fission (ff) or ion implantation, etching and grafting procedure. Poly vinylidene fluoride (PVDF) foils were irradiated during different times to produce pores of different diameters through the foils. In this way, nuclear track membranes (NTM) were produced with different track diameters and track numbers. Active sites were formed using a γ-ray Co-60 source and then contacted with N-isopropylacrylamide (NIPAAm) to obtain a graft copolymer that responds to environmental conditions. The present work shows the grafting yield as a function of: γ-dose, NIPAAm concentration, pore diameter, track density, etc.

Radiofrequency-discharge plasma treatment of heavy ion-irradiated poly(ethylene terephthalate) films

The effects of treatment in a radiofrequency (RF) discharge plasma on the rate of chemical etching of the tracks made by xenon ions (with an energy of ~1 MeV/nucleon) in poly(ethylene terephthalate) (PETP) films were investigated. The influence of plasma treatment conditions on the structure and properties of nuclear track membranes formed by etching was studied. It was found that the RF plasma treatment of heavy ion-bombarded PETP films leads to a decrease in etchability of both tracks and the starting polymer matrix. The changes in track and matrix etchability due to crosslinking of the polymer surface layer were shown to be responsible for the asymmetry of the track membrane structure.

Fabrication and Optical Property of Copper Nanowires in Nuclear Track Membranes

The electrochemical growth of nanowires in nuclear track membranes has been studied and a strong plasma absorption of copper nanowires in the visible region of the electromagnetic spectrum is observed. The result of the plasma absorption is qualitatively in agreement with the prediction of the appropriate formulation of effective medium theory.

The application of nuclear track membranes for ion sampling to mass-spectrometer

Application of track membranes for atmospheric preasure ion sources for mass-spectrometers is described. Theoretical and experimental estimates of gas flow and ion current through track membrane pores are given.

Modification of PEEK model compounds and PEEK film by energetic heavy ion and ultraviolet irradiations

To prepare nuclear track membranes from poly(aryl ether ether ketone) (PEEK) film, we first determined the modifications induced by heavy ion and UV irradiations in this polymer and two of its model compounds, paraphenoxy benzophenone (PPB) and diphenoxy benzophenone (DPB). This article displays the first results obtained by SEC, HPLC, DSC, FTIR, UV and 13C NMR.

Experimental Study of Submicrometer Particle Penetration for Heavy-Ion Track Polyethylene Terephthalate Membranes

The separation characteristics of nuclear track membranes made from l0-μm-thick polyethylene terephthalate film were investigated with submicrometer particles. The measurements were carried out with a submicrometer aerosol indication system and an aerosol laser spectrometer in fixed air flows of 1 L / min. The results obtained are compared with each other and described by the known semiempirical expressions. The effect of the electrostatic charge of microparticles on the filtration efficiency was experimentally studied. The differences between the experimental data obtained and theory and the increasing filtration efficiency for charged aerosols are discussed.

Some basic rules of nuclear track membranes on liquid phase media

Abstract This paper gives a review of the subject on liquid media passing through nuclear track membrane. The following contents will be touched in the paper: 1. 1. Pure liquid medium 1.1. (1) Applicability and limitation of Poiseuille formula 1.2. (2) Viscosity measurement by nuclear track membranes 1.1. 1. Absolute measurement 1.2. 2. Relative measurement 1.1. A. Absolute viscosity measurement with extra pressure 1.2. B. Kinematic viscosity measurement without extra pressure 2. 2. Liquid solution 2.1. Solute concentration determination and its potential usage in industry 3. 3. Liquid phase separation of mixtures 3.1. (1) Principle of liquid phase separation 3.2. (2) Application of liquid phase separation in chemical separation 4. 4. Liquid with microscopic solid particles 4.1. (1) Blocking phenomenon and blocking formula 4.2. (2) Removal of solid particles from liquid by nuclear track microfilters 4.3. (3) Filtration behaviors of bacteria from liquid

Production and investigation of nuclear track membranes at JINR

Abstract In this review the status of the technical and scientific problems associated with the nuclear track membranes is briefly given. The main results obtained in the recent years are presented.

Investigation of efficiency of gas separation on nuclear track membranes with ultra-small pores

The efficiency of the separation of some inert gases (helium, nitrogen, argon, krypton, xenon) and hydrogen on nuclear track membranes of polyethylene terephthalate (PET) with pores of size 2-10 nm have been investigated. The membranes were prepared either by the freeze-drying method or by partial contraction of the porous structure. Membranes with pores over 6 nm in diameter are found to have an ideal gas separation coefficient, close to the theoretical (Knudsen) one, under normal conditions. A gradual decrease in the size of the pores leads to an increase in the reduced ideal separation coefficient of the hydrogen-helium pair for membranes obtained by the freeze-drying method, and in that of the helium-argon and helium-nitrogen pairs for membranes obtained by partial “healing” of pores. For other gas pairs a decrease in the separation coefficients was observed. A theoretical model is proposed that allows description of the observed regularities on the basis of the surface diffusion of components, taking into account the structural peculiarities of the membranes and the isothermal entrainment effects between free and adsorbed gas molecules.