Towards "Precision Mining" of wastewater: Selective recovery of Cu from acid mine drainage onto diatomite supported nanoscale zerovalent iron particles.

This paper introduces the concept of 'Precision Mining' of metals which can be defined as a process for the selective in situ uptake of a metal from a material or media, with subsequent retrieval and recovery of the target metal. In order to demonstrate this concept nanoscale zerovalent iron (nZVI) was loaded onto diatomaceous earth (DE) and tested for the selective uptake of Cu from acid mine drainage (AMD) and subsequent release. Batch experiments were conducted using the AMD and nZVI-DE at 4.0-16.0 g/L. Results demonstrate nZVI-DE as highly selective for Cu removal with >99% uptake recorded after 0.25 h when using nZVI-DE concentrations ≥12.0 g/L, despite appreciable concentrations of numerous other metals in the AMD, namely: Co, Ni, Mn and Zn. Cu uptake was maintained in excess of 4 and 24 h when using nZVI-DE concentrations of 12.0 and 16.0 g/L respectively. Near-total Cu release from the nZVI-DE was then recorded and attributed to the depletion of the nZVI component and the subsequent Eh, DO and pH recovery. This novel Cu uptake and release mechanism, once appropriately engineered, holds great promise as a novel 'Precision Mining' process for the rapid and selective Cu recovery from acidic wastewater, process effluents and leach liquors.

Selective formation of copper nanoparticles from acid mine drainage using nanoscale zerovalent iron particles.

Nanoscale zerovalent iron (nZVI) has been investigated for the selective formation of Cu nanoparticles from acid mine drainage (AMD) taken from a legacy mine site in the UK. Batch experiments were conducted containing unbuffered (pH 2.67 at t = 0) and pH buffered (pH < 3.1) AMD which were exposed to nZVI at 0.1-2.0 g/L. Results demonstrate that nZVI is selective for Cu, Cd and Al removal (>99.9% removal of all metals within 1 h when nZVI ≥ 1.0 g/L) from unbuffered AMD despite the coexistent of numerous other metals in the AMD, namely: Na, Ca, Mg, K, Mn and Zn. An acidic pH buffer enabled similarly high Cu removal but maximum removal of only <1.5% and <0.5% Cd and Al respectively. HRTEM-EDS confirmed the formation of discrete spherical nanoparticles comprised of up to 68% wt. Cu, with a relatively narrow size distribution (typically 20-100 nm diameter). XPS confirmed such nanoparticles as containing Cu°, with the Cu removal mechanism therefore likely via cementation with Fe°. Overall the results demonstrate nZVI as effective for the one-pot and selective formation of Cu°-bearing nanoparticles from acidic wastewater, with the technique therefore potentially highly useful for the selective upcycling of dissolved Cu in wastewater into high value nanomaterials.

Lightweight aerial vehicles for monitoring, assessment and mapping of radiation anomalies.

The Fukushima Daiichi nuclear power plant (FDNPP) incident released a significant mass of radioactive material into the atmosphere. An estimated 22% of this material fell out over land following the incident. Immediately following the disaster, there was a severe lack of information not only pertaining to the identity of the radioactive material released, but also its distribution as fallout in the surrounding regions. Indeed, emergency aid groups including the UN did not have sufficient location specific radiation data to accurately assign exclusion and evacuation zones surrounding the plant in the days and weeks following the incident. A newly developed instrument to provide rapid and high spatial resolution assessment of radionuclide contamination in the environment is presented. The device consists of a low cost, lightweight, unmanned aerial platform with a microcontroller and integrated gamma spectrometer, GPS and LIDAR. We demonstrate that with this instrument it is possible to rapidly and remotely detect ground-based radiation anomalies with a high spatial resolution (<1 m). Critically, as the device is remotely operated, the user is removed from any unnecessary or unforeseen exposure to elevated levels of radiation.

Nanoscale zero-valent iron: future prospects for an emerging water treatment technology.

For the past 15 years, nanoscale metallic iron (nZVI) has been investigated as a new tool for the treatment of contaminated water and soil. The technology has reached commercial status in many countries worldwide, however is yet to gain universal acceptance. This review summarises our contemporary knowledge of nZVI aqueous corrosion, manufacture and deployment, along with methods to enhance particle reactivity, stability and subsurface mobility. Reasons for a lack of universal acceptance are also explored. Key factors include: concerns over the long-term fate, transformation and ecotoxicity of nZVI in environmental systems and, a lack of comparable studies for different nZVI materials and deployment strategies. It is highlighted that few investigations to date have examined systems directly analogous to the chemistry, biology and architecture of the terrestrial environment. Such emerging studies have highlighted new concerns, including the prospect for remobilisation of heavy metals and radionuclides over extended periods. The fundamental importance of being able to accurately predict the long-term physical, chemical and biological fate of contaminated sites following nZVI treatment is emphasised and, as part of this, a universal empirical testing framework for nZVI is suggested.

Magnetite and zero-valent iron nanoparticles for the remediation of uranium contaminated environmental water.

The current work presents a comparative and site specific study for the application of zero-valent iron nanoparticles (nano-Fe(0)) and magnetite nanoparticles (nano-Fe(3)O(4)) for the removal of U from carbonate-rich environmental water taken from the Lisava valley, Banat, Romania. Nanoparticles were introduced to the Lisava water under surface and deep aquifer oxygen conditions, with a U(VI)-only solution studied as a simple system comparator. Thebatch systems were analysed over an 84 day reaction period, during which the liquid and nanoparticulate solids were periodically sampled to determine chemical evolution of the solutions and particulates. Results indicated that U was removed by all nano-Fe(0) systems to <10 µg L(-1) (>98% removal) within 2 h of reaction, below EPA and WHO specified drinking water regulations. Similar U concentrations were maintained until approximately 48 h. X-ray photoelectron spectroscopy analysis of the nanoparticulate solids confirmed partial chemical reduction of U(VI) to U(IV) concurrent with Fe oxidation. In contrast, nano-Fe(3)O(4) failed to achieve >20% U removal from the Lisava water. Whilst the outer surface of both the nano-Fe(0) and nano-Fe(3)O(4) was initially near-stoichiometric magnetite, the greater performance exhibited by nano-Fe(0) is attributed to the presence of a Fe(0) core for enhanced aqueous reactivity, sufficient to achieve near-total removal of aqueous U despite any competing reactions within the carbonate-rich Lisava water. Over extended reaction periods (>1 week) the chemically simple U(VI)-only solution treated using nano-Fe(0) exhibited near-complete and maintained U removal. In contrast, appreciable U re-release was recorded for the Lisava water solutions treated using nano-Fe(0). This behaviour is attributed to the high stability of U in the presence of ligands (predominantly carbonate) within the Lisava water, inducing preferential re-release to the aqueous phase during nano-Fe(0) corrosion. The current study therefore provides clear evidence for the removal and immobilisation of U from environmental waters using Fe-based nanoparticles. As a contrast to previous experimental studies reporting impressive figures for U removal and retention from simple aqueous systems, the present work demonstrates both nanomaterials as ineffective on timescales >1 week. Consequently further research is required to develop nanomaterials that exhibit greater reactivity and extended retention of inorganic contaminants in chemically complex environmental waters.

Nano-scale metallic iron for the treatment of solutions containing multiple inorganic contaminants.

Although contaminant removal from water using zero-valent iron nanoparticles (INP) has been investigated for a wide array of chemical pollutants, the majority of studies to date have only examined the reaction of INP in simple single-contaminant systems. Such systems fail to reproduce the complexity of environmental waters and consequently fail as environmental analogues due to numerous competitive reactions not being considered. Consequently there is a high demand for multi-elemental and site-specific studies to advance the design of INP treatment infrastructure. Here INP are investigated using batch reactor systems over a range of pH for the treatment of water containing multi-element contaminants specifically U, Cu, Cr and Mo, selected to provide site-specific analogues for leachants collected from the Lisava mine, near Oravita in South West Romania. Concurrently, a U-only solution was also analysed as a single-system for comparison. Results confirmed the suitability of nano-Fe(0) as a highly efficient reactive material for the aqueous removal of Cr(IV), Cu(II) and U(VI) over a range of pH applicable to environmental waters. Insufficient Mo(VI) removal was observed at pH >5.7, suggesting that further studies were necessary to successfully deploy INP for the treatment of geochemically complex mine water effluents. Results also indicated that uranium removal in the multi-element system was less than for the comparator containing only uranium.

Protein ProQ influences osmotic activation of compatible solute transporter ProP in Escherichia coli K-12.

ProP is an osmoregulatory compatible solute transporter in Escherichia coli K-12. Mutation proQ220::Tn5 decreased the rate constant for and the extent of ProP activation by an osmotic upshift but did not alter proP transcription or the ProP protein level. Allele proQ220::Tn5 was isolated, and the proQ sequence was determined. Locus proQ is upstream from prc (tsp) at 41.2 centisomes on the genetic map. The proQ220::Tn5 and prc phenotypes were different, however. Gene proQ is predicted to encode a 232-amino-acid, basic, hydrophilic protein (molecular mass, 25,876 Da; calculated isoelectric point, 9.66; 32% D, E, R, or K; 54.5% polar amino acids). The insertion of PCR-amplified proQ into vector pBAD24 produced a plasmid containing the wild-type proQ open reading frame, the expression of which yielded a soluble protein with an apparent molecular mass of 30 kDa. Antibodies raised against the overexpressed ProQ protein detected cross-reactive material in proQ+ bacteria but not in proQ220::Tn5 bacteria. ProQ may be a structural element that influences the osmotic activation of ProP at a posttranslational level.

Intermittent subcutaneous infusion of opioids in hospice home care: an effective, economical, manageable option.

Administration of oral opioids is not always possible for terminally-ill patients. Obstruction, emesis, or inability to swallow frequently force us to seek alternative routes of administration. When the rectal route is contraindicated, impractical, or otherwise rejected by the patient or caregivers, we must resort to the parenteral route. The purpose of this study has been to validate the effectiveness, manageability, and side effects of bolus infusions of opioids utilizing an indwelling subcutaneous butterfly needle. The retrospective chart review included a convenience sample of 50 patients enrolled in our home-based hospice program who required subcutaneous infusion of opioids at some point during their enrollment. The total number of patients served during this time was 112. In the majority of cases (88 percent), the indication was inability to swallow or difficulty swallowing, which was related to impending death. Morphine sulfate was the opiate used in 955 of the cases reviewed. The mean four-hourly dose was 14.3 mg, with a range of 5 to 60 mg. Pain ratings were recorded using a 0-10 scale, both prior to initiation of and during the use of subcutaneous injections. Of the 42 percent of patients able to indicate a pain rating (0-10 scale) all rated their pain at 2 or below while using the subcutaneous route. No objective signs of pain were noted by caregivers or hospice nurses in the 58 percent of patients who were unable to rate their pain. The mean duration of time the needle remained in place was 4.62 days, with a range of 1-26 days.(ABSTRACT TRUNCATED AT 250 WORDS)

A sputtered gold microelectrode in combination with a multibarrelled micropipette: a low impedance extracellular recording electrode with the facility of iontophoresis.

The manufacture of a metal film electrode on a multibarrelled micropipette is described. Gold film is sputtered onto the external surface of a multibarrelled micropipette and subsequently insulated. Gold film exposed at the tip operates as an extracellular recording microelectrode and the micropipettes may be used for iontophoresis of drugs or marker dyes. This method may be used to produce electrodes with increased numbers of iontophoresis channels at the tip without altering the low impedance and good recording characteristics of the metal film (recording) electrode.

A comparison of the dose response effects of pyrimidine ribonucleosides and adenosine on sleep in rats.

The dose-response effects of intracerebroventricular (ICV) infusion of the pyrimidine ribonucleosides cytidine and uridine and the purine ribonucleoside adenosine on sleep and wakefulness (W) in rats were examined and compared. All three drugs were administered at doses of 1,10, and 100 nmol in volumes of 5 microliter, with control animals receiving equivolumetric infusions of 0.9% saline. Treatment with 1 nmol cytidine significantly increased W and decreased both deep slow wave sleep (S2) and total sleep (TS) during both the 3-6 and 0-6 h recording periods. In addition, this dose of cytidine significantly increased light slow wave sleep (S1) during the first 3 h of recording. The 10 nmol dose of cytidine increased W and decreased TS during the 0-6 h recording. ICV administration of uridine produced no significant changes in sleep and W at any dose during any of the recording periods examined. In contrast, adenosine exhibited significant hypnotic effects at all doses examined. All three doses of adenosine significantly reduced W and increased TS during both the 0-3 and 0-6 h recording periods. The 1 and 100 nmol doses of adenosine also significantly increased S2 during both the 0-3 and 0-6 h periods. In addition, the 100 nmol dose of adenosine significantly decreased W and increased both S2 and TS during the second 3 h of recording. Both the 1 and 100 nmol doses of adenosine also significantly reduced the latencies to the onset of rapid eye movement (REM) sleep.(ABSTRACT TRUNCATED AT 250 WORDS)

Water vapor absorption at isotopic CO2 laser wavelengths.

Water vapor absorption at 161 wavelengths, from 9.2 to 11.9 micron, of the 12C1602, 13C1602, and 14CI602 lasers was measured using a resonant optoacoustic spectrometer. Results were obtained at several precisely determined vapor concentrations in a flow of pure air at a total pressure of 1 atm. Since the same apparatus and methodology were used for all measurements, a reliable assessment can be made of the relative merits of the three lasers in applications such as atmospheric propagation and ranging.

Laser optoacoustic absorption spectra for various explosive vapors.

Optoacoustic absorption spectra, using a CO(2) laser source, is reported for ethylene glycol dinitrate, 2, 4 dinitrotoluene, and nitrogylcerine vapors in a nitrogen background. Strong absorption was measured at all seventy-seven laser transitions in the 9.6-microm and 10.6-microm regions. Absorption coefficient data, necessary to evaluate performance as an explosive detector, were obtained for ethylene glycol dinitrate. The strongest feature showed a value of 7.42 atm(-1) cm(-1) giving a minimum detection sensitivity of 8.26 ppb W.

A digital technique for linearising the output of a turbine anemometer.

A technique is described by which it is possible, using digital integrated circuits, to linearise the output of transducers which produce their output in serial digital form. The linearisation technique is used to improve the performance of an anemometer used in the measurement of pulmonary function. The new technique makes possible accurate paediatric measurements using transducers previously intended for adults.