Lifetime improvement of slackened thin cluster carbon stripper foils by suppression of carbon buildup

We control the amount of carbon buildup on slackened thin cluster carbon stripper foils (less than 3.5 μg/cm²) by heating with a high-power infrared lamp during beam bombardment. Foil lifetime measurements were performed using 2.0±0.5 μA beams of 3.2 MeV Ne⁺ ions and quantified as the total charge/area before breakage. Lifetimes were obtained up to 1286 mC/cm² at maximum and 1139 mC/cm² on the average; these values are, respectively, approximately 51 times at maximum and 46 times on average greater than the best commercially available foils, when used unheated and unslackened.     

Wastewater renovation using constructed soil filter (CSF): A novel approach

Constructed soil filter (CSF) also known as Soil Biotechnology (SBT) is a process for water renovation which makes use of formulated media with culture of soil macro- and microorganisms. CSF combines sedimentation, infiltration and biodegradation processes to remove oxidizable organics and inorganics of wastewater in a single facility. Operating experience shows hydraulic loading in the range of 0.05–0.25 m³/m² h and organic loading up to 200–680 g/m² d. The results show increase in dissolved oxygen levels, COD removal (from 352 mg/l to 20 mg/l); BOD removal (from 211 mg/l to 7.0 mg/l); suspended solids removal (from 293 mg/l to 16 mg/l); turbidity reduction (from 145 NTU to 5.3 NTU); iron (from 5 mg/l to 0.3 mg/l); arsenic (from 500 μg/l to 10 μg/l); total coliform and fecal coliform removal (from 145 × 10⁵ to 55 CFU/100 mL and 150 × 10⁸ to 110 CFU/100 mL respectively), with desired pathogen levels as per WHO standards, i.e. ≤10³ CFU/100 mL. CSF reveals advantages such as low HRT (0.5–2.0 h), low energy requirement (0.04 kW h/m³), no pre-treatment, high dissolved oxygen levels in the effluent, no biosludge production, no mechanical aeration and no odor, fish compatible water quality and evergreen ambience.     

Molecular plating of actinides on thin backings

Actinide targets on thick and thin backings are needed for experiments at heavy-ion accelerators. One of the efficient ways to prepare such targets is by molecular plating. Although many laboratories have successfully prepared targets on thick backings by this technique, it is quite difficult to make targets on thin backings (100 μg/cm² up to 1 mg/cm²). In recent years, we have plated targets on thin Ni and carbon backings, for example ²³⁴U targets on a 200 μg/cm² Ni backing. The Ni foils, evaporated on a copper substrate, are available commercially. We used these foils to plate ²³⁴U and afterwards we removed the copper by dissolving it in a mixture of ammoniacal trichloroacetic acid. In this way 400 μg/cm^{2 234}U targets were prepared on a 200 μg/cm² Ni backing. A 100 μg/cm^{2 243}Am target was prepared by plating onto a 75 μg/cm² carbon film left on its glass substrate for later floating. We found that a plating cell made from Teflon was difficult to use because it scratched the C film producing a liquid leak at the joint of the column and the C film. This sealing surface needs to be extremely smooth to avoid leakage. A column made of Delrin™ was then tried and did not produce any scratch on the carbon film surface. This column was used to prepare 100 μg/cm^{2 243}Am targets. Details of the technique will be presented.     

Processing of nanocrystalline 8 mol% yttria-stabilized zirconia by conventional, microwave-assisted and two-step sintering

Manufacturing of near full dense (>97%) 8 mol% yttria-stabilized zirconia (8YSZ) nanopowder (15–33 nm) compacts was manipulated using conventional sintering (CS), two-step sintering (TSS) and microwave-assisted sintering methods. Microwave firing was performed via two different heating rates, i.e. 5 and 50 °C min⁻¹. Although, the lower rate microwave sintering (LMS) was found to yield the higher densities at lower temperatures, this regime ultimately did not provide higher final densities compared to the other methods. The higher rate microwave sintering (HMS) on the other hand managed to suppress the accelerated grain growth and resulted to a finer microstructure (0.9 μm) than LMS (2.35 μm) and CS (2.14 μm). In spite of the great capability of TSS method in fabricating the specimens with ultra-fine grains (0.29 μm), microstructural inhomogeneity and the long total sintering time (>20 h) in comparison with HMS (29 min) set restrictions on the application of TSS method. Based on the effect of grain size on the mechanical properties of ceramics, the specimens produced by TSS exhibited higher fracture toughness (3.16 ± 0.06 MPa m^1/2) than those obtained from CS (1.61 ± 0.07 MPa m^1/2) and LMS (1.9 ± 0.09 MPa m^1/2), due to their finer grain size. The proximity in the fracture toughness values of TSS and HMS (3.17 ± 0.10 MPa m^1/2) samples stems from the higher microstructural homogeneity caused by HMS, while having a larger grain size.     

Citric acid enhances the phytoextraction of manganese and plant growth by alleviating the ultrastructural damages in Juncus effusus L.

Chelate-assisted phytoextraction by high biomass producing plant species enhances the removal of heavy metals from polluted environments. In this regard, Juncus effusus a wetland plant has great potential. This study evaluated the effects of elevated levels of manganese (Mn) on the vegetative growth, Mn uptake and antioxidant enzymes in J. effusus. We also studied the role of citric acid and EDTA on improving metal accumulation, plant growth and Mn toxicity stress alleviation. Three-week-old plantlets of J. effusus were subjected to various treatments in the hydroponics as: Mn (50, 100 and 500 μM) alone, Mn (500 μM) + citric acid (5 mM), and Mn (500 μM) + EDTA (5 mM). After 2 weeks of treatment, higher Mn concentrations significantly reduced the plant biomass and height. Both citric acid and EDTA restored the plant height as it was reduced at the highest Mn level. Only the citric acid (but not EDTA) was able to recover the plant biomass weight, which was also obvious from the microscopic visualization of mesophyll cells. There was a concentration dependent increase in Mn uptake in J. effusus plants, and relatively more deposition in roots compared to aerial parts. Although both EDTA and citric acid caused significant increase in Mn accumulation; however, the Mn translocation was enhanced markedly by EDTA. Elevated levels of Mn augmented the oxidative stress, which was evident from changes in the activities of antioxidative enzymes in plant shoots. Raised levels of lipid peroxidation and variable changes in the activities of antioxidant enzymes were recorded under Mn stress. Electron microscopic images revealed several modifications in the plants at cellular and sub-cellular level due to the oxidative damage induced by Mn. Changes in cell shape and size, chloroplast swelling, increased number of plastoglobuli and disruption of thylakoid were noticed. However, these plants showed a high degree of tolerance against Mn toxicity stress, and it removed substantial amounts of Mn from the media. The EDTA best enhanced the Mn uptake and translocation, while citric acid best recovered the plant growth.     

Microcystins in groundwater wells and their accumulation in vegetable plants irrigated with contaminated waters in Saudi Arabia

The present study describes the presence of toxic cyanobacteria and microcystin (MCYST) concentrations in groundwater wells and tissues of vegetable plants irrigated with well waters in Asir region, southwest of Saudi Arabia. The results revealed the presence of cyanobacteria in all groundwater wells with a dominance of Oscillatoria limentica. This species was found to produce MCYSTs at a concentration of 336 μg g⁻¹ as determined by enzyme-linked immunosorbent assay (ELISA). HPLC chromatogram for the methanolic extract of this species showed one main peak corresponding to MCYST-YR. MCYSTs were also detected in well waters at concentrations (0.3–1.8 μg L⁻¹), exceeding the WHO guideline level (1 μg L⁻¹) in some wells. All vegetable plants collected during the present study were found to accumulate MCYSTs in their leaves and roots at concentrations ranged from 0.07 to 1.2 μg g⁻¹ fresh weight. The study suggests that ground waters and vegetable plants should be continuously monitored for the presence of MCYSTs to protect the public against the exposure to such potent hepatotoxins.     

Determination of heavy metals in skin‐whitening cosmetics using microwave digestion and inductively coupled plasma atomic emission spectrometry

In this study, the determination of noxious heavy metals, cadmium (Cd), bismuth (Bi), mercury (Hg), titanium (Ti), lead (Pb) and metalloid arsenic (As) in skin‐whitening cosmetics were examined using microwave digestion and inductively coupled plasma atomic emission spectrometry method. A complete digestion of cosmetics samples was achieved using a mixture of hydrofluoric acid/hydrogen peroxide/nitric acid. The quantification of the target compounds was done by standard addition method. The excellent quality parameters for instance, detection limits, As (4.6 ppb), Bi (7.9 ppb), Cd (0.45 ppb), Hg (3.3 ppb), Pb (3.8 ppb), Ti (4.3 ppb), linearity (r ²  > 0.999) and run‐to‐run and day‐to‐day precisions with relative standard deviations <3% were obtained. The recovery rates for standard reference materials were found between 90 and 105%. The average concentration of heavy metals in cosmetics samples were in the range of 1.0–12.3 (μg g⁻¹, As), 33–7097 (μg g⁻¹, Bi), 0.20–0.6 (μg g⁻¹, Cd), 0.70–2700 (μg g⁻¹, Hg), 1.20–143 (μg g⁻¹, Pb) and 2.0–1650 (μg g⁻¹, Ti).Inspec keywords: cosmetics, atomic emission spectroscopyOther keywords: skin‐whitening cosmetics, microwave digestion, plasma atomic emission spectrometry, noxious heavy metals, cadmium, bismuth, mercury, titanium, lead, metalloid arsenic, hydrofluoric acid, hydrogen peroxide, nitric acid, standard addition method, standard reference materials     

Ultrasonic irradiation-induced degradation of low-concentration bisphenol A in aqueous solution

Lead (Pb) contamination in the black paper that recovers intraoral films (BKP) has been investigated. BKP samples were collected from the Radiology Clinics of the Dental School of Ribeirão Preto, University of São Paulo, Brazil. For sake of comparison, four different methods were used. The results revealed the presence of high lead levels, well above the maximum limit allowed by the legislation. Pb contamination levels achieved after the following treatments: paper digestion in nitric acid, microwave treatment, DIN38414-54 method and TCLP method were 997 μg g⁻¹, 189 μg g⁻¹, 20.8 μg g⁻¹, and 54.0 μg g⁻¹, respectively. Flame atomic absorption spectrometry (FAAS) and inductively coupled plasma mass spectrometry (ICP-MS) were employed for lead determination according to the protocols of the applied methods. Lead contamination in used BKP was confirmed by scanning electron microscopy coupled with energy dispersive X-ray microanalysis (SEM-EDS). All the SEM imaging was carried out in the secondary electron mode (SE) and backscattered-electron mode (QBSD) following punctual X-ray fluorescence spectra. Soil contamination derived from this product revealed the urgent need of addressing this problem. These elevated Pb levels, show that a preliminary treatment of BKP is mandatory before it is disposed into the common trash. The high lead content of this material makes its direct dumping into the environment unwise.     

Determination of cadmium at ultra-trace levels by CPE–molecular fluorescence combined methodology

A highly sensitive micelle-mediated extraction methodology for the preconcentration and determination of trace levels of cadmium by molecular fluorescence has been developed. Metal was complexed with o-phenanthroline (o-phen) and eosin (eo) at pH 7.6 in buffer Tris medium and quantitatively extracted into a small volume of surfactant-rich phase of PONPE 7.5 after centrifugating. The chemical variables affecting cloud point extraction (CPE) were evaluated and optimized. The RSD for six replicates of cadmium determinations at 0.84 μg L⁻¹ level was 1.17%. The linearity range using the preconcentration system was between 2.79 × 10⁻³ μg L⁻¹ and 2.81 μg L⁻¹ with a correlation coefficient of 0.99. Under the optimal conditions, it obtained a LOD of 8.38 × 10⁻⁴ μg L⁻¹ and LOQ of 2.79 × 10⁻³ μg L⁻¹. The method presented good sensitivity and selectivity and was applied to the determination of trace amounts of cadmium in commercially bottled mineral water, tap water and water well samples with satisfactory results. The proposed method is an innovative application of CPE-luminescence to metal analysis comparable in sensitivity and accuracy with atomic spectroscopies.     

Carbon micro-ribbon and strip polarimeter targets for the AGS and RHIC

Current techniques used to produce carbon micro-ribbon targets 5 μm wide×3.7–4.5 μg/cm²×25-mm long will be described. Developmental emphasis was to provide nearly identical micro-ribbons with the minimum number of atoms per unit of length, and to position them within ±0.5 mm of the desired location on C-shaped frames.The foil strip targets to be described were 200–600 μm wide×3.7–4.5 μg/cm²×51 mm long. These were produced from 25-mm-wide carbon film deposits that were scribed using a jig prior to dissolving the betaine/sucrose release agent under ethanol.Both types of targets required methods and devices that differed significantly from those reported previously for substrate texturing, masking, vacuum deposition, releasing from the substrate, and mounting. Sets of 12–24 of the targets have been made for the 2006 run period at BNL.     

Preparation of isotopic Zn and Cd targets

^nat,68Zn and ^natCd have been reduced from their oxides with high yields (about 90%) using carbon as reductant. A water-cooled copper pin collector was used resulting in higher yield and better reproducibility. ^natZn and ^{nat, 113, 116}Cd targets of 20–3000 μg/cm² on carbon backings of 20 μg/cm² have been deposited by focused ion beam sputtering. ^{67, 68, 70}Zn targets of 200–400 μg/cm² on iron backings of about 1.3 mg/cm² have been prepared using a rotating substrate setup to improve target homogeneity. Using a special rolling technique, ^{64, 66, 68, 70}Zn and ^{110, 114, 116}Cd have also been rolled to thin foils.     

Preparation of isotopically enriched mercury sulphide targets

Production of HgS targets, based on HgO, is described. The HgS is precipitated from HgO dissolved in diluted HNO₃ by gaseous H₂S. Subsequently the target is manufactured by evaporation–condensation of HgS in vacuum. This way the ²⁰⁴HgS layers of 500 μg/cm² on a backing carbon foil of 26 μg/cm² were produced.     

Gas permeability of thin polyimide foils prepared by in-situ polymerisation

The entrance windows to the gas detector chambers as well as to the target containers used in high-energy and high-intensity accelerators must be as thin as possible to minimise energy losses of the particles used in astrophysics and nuclear physics studies. Because of their good physical properties, polyimide foils are often considered as suitable material for such windows, but commercially available foils, having a thickness greater than 7–8 μm (>1 mg/cm²), would cause energy losses of particles significant for some nuclear reactions studied. Foils prepared by in-situ polymerisation can, however, be as thin as 0.07 μm (10 μg/cm²). The permeability of 4 μm foils produced by in-situ polymerisation has been measured at room temperature for He and Ar. For He measurements were performed in the pressure range of 4–70 mbar and for Ar in the range of 20–140 mbar and the permeability was found to be in good agreement with the values published for the thicker commercial foils.     

Polymer coating method developed for carbon stripper foils

The problem of handling the fragile carbon foils (mounting on the frame, placing in the stripper changer) that easily break when self-supporting has been solved by coating carbon foils with poly-monochloro-para-xylylene. It was found that the polymer-coating method could also be used to produce carbon foils thicker than 100 μg/cm² by alternated deposition of carbon and poly-monochloro-para-xylylene layers. Carbon foil of 500 μg/cm² thick and 10 cm in diameter was produced by this method and mounted to a foil holder. Results of lifetime measurement for singly coated foils are also presented.     

Simple and selective extraction process for chromium (VI) in industrial wastewater

A simple and relatively green method has been developed for the determination of chromium based on the extraction of chromium (VI) as its ion-association complex with tetrabutylammoniumiodide (TBAI) in acidic medium. The ion-pair is extracted using isobutylmethylketone (MIBK) as the solvent. The concentration of the extracted chromium (VI) in the organic layer was measured spectrophotometrically at a wavelength maximum of 366 nm and the organic layer was characterized using FT-IR spectroscopy. The influence of various analytical parameters such as pH, aqueous phase volume, equilibration time, interfering ions etc. has been studied in detail. The extracted chromium (VI) was back extracted into the aqueous phase to the non-toxic chromium (III) using ascorbic acid. The calibration graph was linear in the range of 0–2 μg mL⁻¹ chromium (VI) with a relative standard deviation of 2.4%. A detection limit of 0.25 μg in 25 mL aqueous phase volume could be achieved and the validity of the proposed method has been checked by applying it to synthetic mixtures, spiked water sample, electroplating wastewater and certified reference material BCR^®-715.     

Improvement of thickness and uniformity of isotopically enriched C targets on backings by the HIVIPP method

We have made enriched ¹²C targets to accurately measure the cross-section of the ¹²C(α,γ)¹⁶O reaction, which is very important in nuclear astrophysics. Isotopically enriched ¹²C targets for studying this small cross-section, especially for use with an intense pulsed α beam was desired to meet the following requirements: (1) use of impurity-free enriched ¹²C, (2) stability for a long time measurement and (3) uniform thickness in the range 200–300 μg/cm². To meet these experimental requirements, isotopically enriched amorphous ¹²C powder was converted into graphite powder in an electric furnace at a temperature of 3000 K and subsequently the graphite powder was deposited on a thick Au backing via the HIVIPP method. Targets thus prepared could be made thicker than 200 μg/cm². They had a good uniformity and a very high stability against irradiation with high intensity ion beams.     

Fabrication of W target on carbon backing

¹⁸⁴W enriched isotopic target of 210 μg/cm² thickness on carbon backing of 100 μg/cm² thickness has been made in ultra-high vacuum environment by evaporation method using 6 kW electron beam at Inter University Accelerator Centre (IUAC). Hundred and thirty milligrams of enriched ¹⁸⁴W powder was used in this target preparation process. This target has been successfully used in two nuclear reaction experiments performed at IUAC. Methods adopted to convert the tungsten powder to a special pellet form in order to minimize the consumption of the expensive material, preparation of stress relieved carbon-backing foil, steps taken to make the carbon withstand the heat generated during the tungsten evaporation, the method of tungsten fabrication and details of ultra-high vacuum evaporator facility of IUAC are discussed.     

Emissions properties of Ho: I7 → I8 transition sensitized by Er and Yb in fluorophosphate glasses

Emission properties of Ho³⁺ at 2.0 μm and the energy transfer mechanism between Yb³⁺, Er³⁺ and Ho³⁺ ions in fluorophosphate glasses are investigated. The measured emission spectra show that the ⁵I₇ → ⁵I₈ transition of Ho³⁺ upon 980 nm laser diode excitation is strong. Judd–Ofelt intensity parameters (Ω_λ, λ = 2, 4, 6), spontaneous transition probability (A_rad), radiative lifetime (τ_r), absorption cross section (σ_a), stimulated emission cross section (σ_e) and FWHM ×  for the transition of Ho³⁺: ⁵I₇ → ⁵I₈ are calculated and discussed. The obtained results show that the present Yb³⁺/Er³⁺/Ho³⁺ triply-doped fluorophosphate glass can be identified to be a promising material at 2.0 μm emission.     

Preparation of nano-sized magnetic particles from spent pickling liquors by ultrasonic-assisted chemical co-precipitation

This work focuses on the possible use of phenanthro[9,10-c]-1,2,5-thiadiazole 1,1-dioxide (TDZ) as a harmless corrosion inhibitor. TDZ range-dose providing minimum adverse effects to the environment and human health, with satisfactory corrosion-inhibiting properties was evaluated. Cytotoxicity and genotoxicity of TDZ at 0.57–12.50 μM concentration range were tested by neutral red, chromosomal aberrations, mitotic index, and colony formation assays. Results showed a significant increase of chromatid-type aberrations for the highest concentration of TDZ assayed (12.50 μM). Additionally, a reduction in the proliferative rate for lower concentrations was detected by the MI assay. We concluded that TDZ should be used at concentrations lower than 1.16 μM. Corrosion assays performed showed good inhibition effect (ca. 50%) at low (0.65 μM) TDZ concentration. Consequently, our results indicated that TDZ induced a time- and dose-dependent genotoxic and cytotoxic response on CHO-K1 cells. Short assays should be complemented with long exposure tests to simulate chronic contact with TDZ since lower threshold levels may be found for shorter exposures and a wrong safety range could be determined.     

Meteorological variations of PM2.5/PM10 concentrations and particle-associated polycyclic aromatic hydrocarbons in the atmospheric environment of Zonguldak, Turkey

Airborne particulate matter (PM_2.5 and PM₁₀) concentrations were measured in Zonguldak, Turkey from January to December 2007, using dichotomous Partisol 2025 sampler. Collected particulate matter was analyzed for 14 selected polycyclic aromatic hydrocarbons (PAHs) by high-performance liquid chromatography with fluorescence detection (HPLC-FL). The seasonal variations of PM_2.5 and PM₁₀ concentrations were investigated together with their relationships with meteorological parameters. The maximum daily concentrations of PM_2.5 and PM₁₀ reached 83.3 μg m⁻³ and 116.7 μg m⁻³ in winter, whereas in summer, they reached 32.4 μg m⁻³ and 66.7 μg m⁻³, respectively. Total concentration of PM₁₀-associated PAHs reached 492.4 ng m⁻³ in winter and 26.0 ng m⁻³ in summer times. The multiple regression analysis was performed to predict total PM_2.5- and PM₁₀-associated PAHs and benzo(a)pyrene-equivalent (BaPE) concentrations with respect to meteorological parameters and particulate mass concentrations with the determination coefficients (R²) of 0.811, 0.805 and 0.778, respectively. The measured mean values of concentrations of total PM_2.5- and PM₁₀-associated PAHs were found to be 88.4 ng m⁻³ and 93.7 ng m⁻³ while their predicted mean values were found to be 92.5 ng m⁻³ and 98.2 ng m⁻³, respectively. In addition, observed and predicted mean concentration values of PM_2.5-BaPE were found to be 14.1 ng m⁻³ and 14.6 ng m⁻³. The close annual mean concentrations of measured and predicted total particulate related PAHs imply that the models can be reliably used for future predictions of particulate related PAHs in urban atmospheres especially where fossil fuels are mainly used for heating.