Chemiluminescence from the oxidation of urea and ammonia with hypobromite and N-bromosuccinimide

The spectral distribution for the chemiluminescent oxidation of ammonia with hypobromite is significantly different to that for the oxidation of ammonia with N-bromosuccinimide. Therefore, in contrast to the assumptions of several authors, the action of N-bromosuccinimide is not solely derived from the in situ formation of hypobromite. Neither the oxidation of urea with hypobromite nor the oxidation of urea with N-bromosuccinimide involves an initial hydrolysis of urea to ammonia in the alkaline solution. However, these two reactions lead to a common emitter. The addition of xanthene dyes, such as dichlorofluorescein, enhance the chemiluminescence intensity by energy transfer to the efficient fluorophore, but reaction between the sensitiser and hypobromite can result in a significant increase in the background signal. A list of potential interferences has been compiled; particular attention was paid to guanidino compounds, as the chemiluminescence accompanying the oxidation of this functional group has not been previously discussed.

Ammonia dissociation in the fluidised bed furnace

Ammonia dissociation is the controlling reaction for several important thermochemical heat treatment processes; nitriding, nitrocarburising (ferritic and austenitic) and carbonitriding. The fluidised bed furnace is a convenient and widely used medium for all of these treatments, yet understanding of the reaction in a fluidised bed context is minimal. This paper deals with the influence of process parameters on nitrogen activity aN; temperature, fluidising flowrate, ammonia inlet level, carbonaceous gas. Two basic behaviours were observed; inlet NH3-dependant and inlet NHr insensitive, with a transition region at intermediate temperatures. The nitrocarburising response of steel specimens was measured by optical microscopy of the layer thicknesses and glow discharge optical emission spectroscopy (GD-OES) determination of nitrogen depth-penetration profiles. aN was found by gas analysis of the exit stream ammonia with the aid of a dissociation burette.

Near-ultraviolet chemiluminescence from the reaction of ammonia with hypobromite in aqueous solution

The chemiluminescence arising from the oxidation of ammonium chloride by sodium hypobromite in aqueous alkaline solution includes a series of peaks in the near-ultraviolet, which is not commonly observed in liquid-phase chemiluminescence. The dominant peak in that region has an intensity maximum at 292 nm and smaller peaks are observed at 313, 334 and 356 nm. The emitted photons are of similar energy to the Vergard–Kaplan transition of molecular nitrogen, a major product of this reaction. However, the spectral distribution is different to that of previously reported gas-phase chemiluminescence attributed to the Vergard–Kaplan transition.

Simultaneous removal of ammonia and phosphate from wastewater by precipitation of struvite using magnesia

A thorough investigation of conditions required for the precipitation of magnesium ammonium phosphate hexahydrate using magnesia as the source of magnesium was carried out and two computer models were used to make predictions as to optimum conditions for production of suitable crystal size and structure for a successful process. A process was developed and a bench scale model operated for a number of high ammonia wastes. Removal of ammonia was affected to levels of up to 97% with 94% ammonia removal being achievable consistently.

Ammonia nitrogen removal from aqueous solution using functionalized zeolite columns

In this study, a functionalized zeolites column was developed to remove ammonia nitrogen with a low concentration (50 mg/L) from aqueous solution. The absorption properties and regeneration capacity were investigated. Through breakthrough and elution curve for dynamic adsorption, we found the wastewater with 50 mg/L ammonia nitrogen took 7 h to flow 10 g modified zeolites column with diameters of 24 to 64 meshes at a flow rate of 2 mL/min. The saturated extent of adsorption was up to 7.95 mg/g, and the saturated adsorption time was 22 h. The process of dynamic adsorption could be fitted by the Thomas Model. The regeneration ability was optimized by 0.1 M Na2CO3 as a regenerant. With excellent absorption ability for removing ammonia nitrogen with a low concentration, the functionalized zeolites could be potentially used a high-performance adsorbent for removing ammonia nitrogen.

A superamphiphobic coating with an ammonia-triggered transition to superhydrophilic and superoleophobic for oil-water separation

Superhydrophilic and superoleophobic materials are very attractive for efficient and cost-effective oil-water separation, but also very challenging to prepare. Reported herein is a new superamphiphobic coating that turns superhydrophilic and superoleophobic upon ammonia exposure. The coating is prepared from a mixture of silica nanoparticles and heptadecafluorononanoic acid-modified TiO2 sol by a facile dip-coating method. Commonly used materials, including polyester fabric and polyurethane sponge, modified with this coating show unusual capabilities for controllable filtration of an oil-water mixture and selective removal of water from bulk oil. We anticipate that this novel coating may lead to the development of advanced oil-water separation techniques.

A PAL1 gene promoter-green fluorescent protein reporter system to analyse defence responses in live cells of Arabidopsis thaliana

Arabidopsis thaliana ecotype Columbia-0 was transformed with a green fluorescent protein (GFP) gene under control of a phenylalanine ammonia-lyase (PAL) promoter. PAL is a key enzyme of the phenylpropanoid pathway and is induced to high levels during plant stress. Constitutive expression of PAL1 promoter-controlled GFP occurred in vascular tissues within stems, leaves and roots and in developing flowers. PAL1 promoter–GFP expression was examined in leaves of transgenic plants subjected to an abiotic elicitor, mechanical wounding or to inoculation with the pathogens Pseudomonas syringae pv. tomato or Peronospora parasitica. Wounding of leaves and treatment with an abiotic elicitor and compatible interactions produced low to moderate levels of GFP. However, in incompatible interactions there were high levels of GFP produced. In incompatible interactions, the intensity of GFP fluorescence was similar to that produced in transgenic plants expressing GFP driven by the CaMV promoter. The bright green fluorescence produced in live cells and tissues was readily visualised using conventional fluorescence microscopy and was quantified using spectroflourometry. This is the first report of the use of GFP as a reporter of defence gene activation against pathogens. It has several advantages over other reporter genes including real time analysis of gene expression and visualisation of defence gene activation in a non-invasive manner.

The emitting species formed by the oxidation of hydrazides with hypohalites or N-halosuccinimides

The chemiluminescence accompanying the oxidation of salicylic hydrazide (2-hydroxybenzoic acid hydrazide) with hypochlorite, hypobromite, N-chlorosuccinimide, N-bromosuccinimide or hydrogen peroxide with cobalt(II) matched the photoluminescence emission of salicylic acid. In a related reaction, the oxidation of a mixture of isoniazid and ammonia, a synergistic effect was observed. The chemiluminescence spectrum for this reaction matches that accompanying the oxidation of the hydrazide, rather than the oxidation of ammonia. These results were used to assess mechanisms proposed by previous authors.

The determination of urea in wine – a review

The concentration of urea in wine is not routinely measured in Australian laboratories, but has been examined in studies of yeast metabolism and the formation of ethyl carbamate, a known carcinogen. For alcoholic beverages that may contain high levels of urea, steps have been taken to reduce the concentration of urea and therefore prevent ethyl carbamate production. Methods for the determination of urea in wine can be grouped into three categories that indicate how selectivity for urea is achieved; those based on colour-forming reactions, enzymatic hydrolysis and chromatographic separation. The two dominant methods used by research groups over the past fifteen years for the determination of urea in wine are based on the urea/ammonia test kit available from Boeringer Mannheim/R-Biopharm and the reaction of urea with 1-phenyl-1,2-propanedione-2-oxime; both are time-consuming and labour-intensive, but involve relatively straightforward and well-established procedures. However, other options are available that may be better suited to the desired application and the instrumentation available in any particular laboratory.

Lupin kernel fibre foods improve bowel function and beneficially modify some putative faecal risk factors for colon cancer in men.

Consumption of some dietary fibres may benefit bowel health; however, the effect of Australian sweet lupin (Lupinus angustifolius) kernel fibre (LKFibre) is unknown. The present study examined the effect of a high-fibre diet containing LKFibre on bowel function and faecal putative risk factors for colon cancer compared to a control diet without LKFibre. Thirty-eight free-living, healthy men consumed an LKFibre and a control diet for 1 month each in a single-blind, randomized, crossover study. Depending on subject energy intake, the LKFibre diet was designed to provide 17–30 g/d fibre (in experimental foods) above that of the control diet. Bowel function self-perception, frequency of defecation, transit time, faecal output, pH and moisture, faecal levels of SCFA and ammonia, and faecal bacterial [ß]-glucuronidase activity were assessed. In comparison to the control diet, the LKFibre diet increased frequency of defecation by 0·13 events/d (P = 0·047), increased faecal output by 21 % (P = 0·020) and increased faecal moisture content by 1·6 % units (P = 0·027), whilst decreasing transit time by 17 % (P = 0·012) and decreasing faecal pH by 0·26 units (P < 0·001). Faecal butyrate concentration was increased by 16 % (P = 0·006), butyrate output was increased by 40 % (P = 0·002) and [ß]-glucuronidase activity was lowered by 1·4 µmol/h per g wet faeces compared to the control diet (P < 0·001). Addition of LKFibre to the diet incorporated into food products improved some markers of healthy bowel function and colon cancer risk in men.

Extraction of compounds associated with water repellency in sandy soils of different origin

After an initial evaluation of several solvents, the efficiency of Soxhlet extractions with isopropanol/ammonia (s.g. 0.88) (70 : 30 v : v; 24 h) in extracting compounds associated with water repellency in sandy soils was examined using a range of repellent and wettable control soils (n = 15 and 4) from Australia, Greece, Portugal, The Netherlands, and the UK. Extraction efficiency and the role of the extracts in causing soil water repellency was examined by determining extract mass, sample organic carbon content and water repellency (after drying at 20°C and 105°C) pre- and post-extraction, and amounts of aliphatic C–H removed using DRIFT, and by assessing the ability of extracts to cause repellency in acid-washed sand (AWS).

Key findings are: (i) none of organic carbon content, amount of aliphatic C–H, or amount of material extracted give any significant correlation with repellency for this diverse range of soils; (ii) sample drying at 105°C is not necessarily useful before extraction, but may provide additional information on extraction effectiveness when used after extraction; (iii) the extraction removed repellency completely from 13 of the 15 repellent samples; (iv) extracts from all repellent and wettable control soils were capable of inducing repellency in AWS. The findings suggest that compounds responsible for repellency represent only a fraction of the extract composition and that their presence does not necessarily always cause repellency.

Creatine supplementation reduces muscle inosine monophosphate during endurance exercise in humans

Introduction: Creatine (Cr) supplementation has been shown to attenuate increases in plasma ammonia and hypoxanthine during intense endurance exercise lasting 1 h, suggesting that Cr supplementation may improve muscle energy balance (matching of ATP resynthesis to ATP demand) during such exercise. We hypothesized that Cr supplementation would improve muscle energy balance (as assessed by muscle inosine monophosphate (IMP) accumulation) during intense endurance exercise.

Methods: Seven well-trained men completed two experimental trials involving approximately 1 h of intense endurance exercise (cycling 45 min at 78 ± 1% V̇O_2peak followed by completion of 251 ± 6 kJ as quickly as possible (performance ride)). Subjects ingested approximately 42 g·d^-1 dextrose for 5 d before the first experimental trial (CON), then approximately 21 g Cr monohydrate plus approximately 21 g·d^-1 dextrose for 5 d before the second experimental trial (CREAT). Trials were ordered because of the long washout time for Cr. Subjects were blinded to the order of the trials.

Results: Creatine supplementation significantly (P < 0.05) increased muscle total Cr (resting values: CREAT: 138.1 ± 7.9; CON: 117.7 ± 6.5 mmol·kg^-1 dm). No difference was seen between treatments in any measured muscle or blood metabolite after the first 45 min of exercise. Despite the performance ride completion time being similar in the two treatments (∼13.5 min, ∼86% V̇O_2peak), IMP at the end of the performance ride was significantly (P < 0.05) lower in CREAT than in CON (CREAT: 1.2 ± 0.6; CON: 2.0 ± 0.7 mmol·kg^-1 dm).

Changes in bacterial concentration in the liver correlate with that in the hepaticojejunostomy after bile duct reconstruction: implication in the pathogenesis of postoperative cholangitis

Postoperative cholangitis is a frequent and unpredictable complication of unknown etiology following bile duct reconstruction (BDR), particularly for biliary atresia. This study was undertaken to correlate the growth of bacteria in the hepaticojejunostomy with that in the liver after BDR. Quantitative bacterial culture was done on the specimens taken from the liver and from the hepaticojejunostomy at 1 week (group 1, n = 7), 1 month (group 2, n = 7), and 2 months (group 3, n = 7) following BDR with Roux-en-Y hepaticojejunostomy in piglets after 2 weeks of common bile duct ligation. The histological examination of the liver and the hepaticojejunostomy, as well as serial monitoring of hemogram and liver function tests, were performed to correlate the findings with the bacterial concentration of the liver and the hepaticojejunostomy following BDR. The bacterial concentration of the hepaticojejunostomy, expressed as log10 colony-forming units per gram (log10 CFU/g) of the hepaticojejunostomy, showed a progressive decrease from 8.38 ± 1.36 in group 1, 7.07 ± 2.54 in group 2, to 3.56 ± 1.31 in group 3 (p = 0.001). The log10 CFU/g of the liver also showed a progressive decrease from 5.02 ± 1.59 in group 1, 3.16 ± 1.56 in group 2, to 2.19 ± 1.09 in group 3 (p = 0.006). There was a significant positive correlation of the log10 CFU/g of the liver (n = 21) with that of the hepaticojejunostomy (n = 21) following BDR (r = 0.600, p = 0.004). Most of the infectious pathogens isolated from the liver were also isolated from the hepaticojejunostomy. The changes in hemoglobin, bilirubin, albumin, and ammonia significantly correlated with the changes of the bacterial concentration of the liver. The results of the study suggests that hepatic bacterial proliferation after BDR is significantly affected by microbial overgrowth in the bilioenteric anastomosis and is associated with deteriorated liver function and hemogram.

Investigation of compounds causing water repellency in the rhizosphere of sandy soils from a wide range of locations.

Although soils are generally considered to wet readily, some are actually water repellent at the surface and in the rhizosphere. This phenomenon occurs at low to moderate moisture contents and has been reported from soils under a range of vegetation types and from many regions around the globe. Water repellency in soils can have serious environmental implications including reduced seed germination and plant growth as well as irrigation efficiency, accelerated soil erosion, and enhanced leaching of agrochemicals through preferential flow. it has been proposed that water repellency is caused by the accumulation of hydrophobic organic compounds released as root exudates, microbial byproducts or from decomposing organic matter, which are deposited on mineral or aggregate surfaces, or are present as interstitial matter, Few studies to date have attempted to isolate and characterize these compounds and their structure is therefore only poorly understood, These studies have generally focussed on only a single soil or a small range of samples, have not included non-repellent soils as a control and have not always been able to demonstrate that the substances isolated are indeed responsible for repellency formation.

This study reports on the first part (extraction procedures) of a research programme addressing these gaps in current knowledge by investigating a wide range of severely repellent and wettable ‘control’ samples from different countries, and by including assessments of extraction efficiency and ability of extracts to cause repellency. Analytical methods include DRIFT (Diffuse Reflectance Infrared Fourier Transform Spectroscopy) of soils and IR (Infrared) analysis of extracts.

Key findings are that (i) soil sample heating after extraction is valuable in assessing the effectiveness of the extraction procedure, (ii) Soxhlet extraction using isopropanol/ ammonia (70/30 v/v) was the most effective method in extracting hydrophobic compounds, while leaving the ability of extracted compounds to induce water repellency virtually unaffected, (iii) wettable control soils also contain hydrophobic substances capable of inducing water repellency, (iv) the amount of organic compounds extracted was poorly related to sample repellency, indicating that compounds responsible for repellency may only represent a small fraction of the extract, (v) differences in extraction efficiency between different samples indicate that the compounds responsible may differ generically and/or in terms of their bonding to minerals, and (vi) the combination of repellency assessments with DRIFT on soils and JR on extracts used with internal standards has considerable potential to allow quantification of CH bearing organic matter in the soil, the efficiency of extraction processes for its removal, and its significance in causing water repellency in soils.