Addition Of HNO Research Articles

A rhodamine-based fluorescent probe used to determine nitroxyl (HNO) in lysosomes

The reactive nitrogen species (RNS) in lysosomes play a major role during the regulation of lysosomal microenvironment. Nitroxyl (HNO) belongs to active nitrogen species (RNS) and is becoming a potential diagnostic and therapeutic biomarker. However, the complex synthesis routes of HNO in biosystem always hinder the exact determination of HNO in living cells. Here, a rhodamine-based fluorescent probe used to determine nitroxyl (HNO) in lysosomes was constructed and synthesized. 2-(Diphenylphosphino)benzoate was utilized as the sensing unit for HNO and morpholine was chose as the targeting group for lysosome. Before the addition of HNO, the probe displayed a spirolactone structure and almost no fluorescence was found. After the addition of HNO, the probe existed as a conjugated xanthene form and an intense green fluorescence was observed. The fluorescent probe possessed fast response (3 min) and high selectivity for HNO. Furthermore, fluorescence intensity of the probe linearly related with the HNO concentration in the range of 6.0 × 10−8 to 6.0 × 10−5 mol L−1. The detection limit was found to be 1.87 × 10−8 mol L−1 for HNO. Moreover, the probe could selectively targeted lysosome with excellent biocompatibility and had been effectually utilized to recognize exogenous HNO in A549 cells.

Effect of clay on the fractions of potentially toxic elements in contaminated soil

The aim of the study was to evaluate the effect of clay as an amendment to decrease the mobility and plant availability of potentially toxic elements (PTEs). Kaolinite and vermiculite were added at a 9% application rate to a contaminated garden soil from Kutná Hora. Half of the original soil was acidified by the addition of HNO<sub>3</sub>, to observe the effect of the pH on the adsorption of the PTEs. The samples were analysed four times over an eight-week period to evaluate the effect of the clay additions on the As, Cd, Pb and Zn plant availability and different fractions of the BCR sequential extraction. The results indicate that the PTEs were mainly bound by ion/cation exchange on the edges of the clay minerals and onto the Fe/Mn oxides and organic fractions in the soils. The significance (P < 0.05) of the pH was observed for the plant availability of the PTE, especially on the As and Cd. A comparison of the vermiculite in the form of chunks and as powder displayed the most statistically significant results, where the vermiculite powder significantly decreased the plant availability of the As, Cd and Pb, while the opposite effect was observed for the Zn.

Soft chemical transformation of α-MoO3 to β-MoO3 as a catalyst for vapor-phase oxidation of methanol

Abstract Monoclinic molybdenum trioxide, β-MoO 3 , was synthesized as an active catalyst for vapor-phase oxidation of methanol by a soft chemical transformation of α-MoO 3 . The addition of HNO 3 to an aqueous solution of α-MoO 3 , followed by drying and calcination, resulted in the formation of yellow powders consisting of β-MoO 3 . The β-MoO 3 content increased with the amount of HNO 3 , but the addition of excess HNO 3 inhibited β-MoO 3 formation. The maximum yield was obtained at a HNO 3 /Mo molar ratio of 0.37. Thermal analyses indicated that HNO 3 controlled dehydration of the dried precursor to induce β-phase formation. The resulting β-MoO 3 had a higher activity than α-MoO 3 in the partial oxidation of methanol to formaldehyde at temperatures below 600 K.

Co-precipitation in aqueous medium of La 0.8Sr 0.2Ga 0.8Mg 0.2O 3− δ via inorganic precursors

A simple and inexpensive co-precipitation route in aqueous medium is proposed to prepare La 0.8Sr 0.2Ga 0.8Mg 02O 3− δ ionic conductor (LSGM). Different synthetic procedures and operating parameters (i.e. nature and amount of the precipitating agents, HNO 3 addition and temperature) have been evaluated in order to underline their influence on the composition and microstructure of the final phase. Intermediate and final products were characterized by Thermal-Gravimetry, IR-spectroscopy, X-ray Powder Diffraction, Rietveld analysis and Scanning Electron Microscopy. The electrical properties were measured by Impedance Spectroscopy in the temperature range 250–800 °C. Slight variations of the synthetic procedure (such as precipitating agent amount or no HNO 3 addition) have a considerable and detrimental effect on the ions losses and the subsequent achievement of the final phase. The use NH 4OH as an alternative precipitating agent is dramatically disadvantageous. Ions losses during precipitation must be controlled (i) to avoid understoichiometry in the LSGM phase and (ii) to prevent the formation of large amounts of secondary phases. In fact, both affect the total electrical conductivity. The use of large excess of (NH 4) 2CO 3 precipitating agent and the addition of HNO 3 lead to the best material characterized by a rhombohedral structure, small amount of side phases, a relative density of 98% and a total conductivity of 6.44 × 10 −2 S cm −1 at 800 °C and 1.13 × 10 −2 S cm −1 at 600 °C.

Effect of nitric acid on radiation stability and radiolysis product of N,N-Diethylhydroxylamine

This paper reports the effect of HNO 3 on radiation stability and radiolysis product of N,N-Diethylhydroxylamine (DEHA), which is used as a reducer in the reprocessing of spent fuel. Results show that with the addition of HNO 3, radiation stability of DEHA is weakened obviously, the volume fraction of H 2, CH 4 and C 2H 4 decreases but the concentration of CH 3COOH increases. As to 1.0 and 2.0 M HNO 3, the concentration of CH 3CHO increases, but it decreases when HNO 3 is 3.0 M.

A novel electrochromic device with high optical switching speed

An electrochromic device (ECD) with the configuration of ITO/WO 3/propylene carbonate (PC)+LiClO 4+HNO 3/NiO/ITO has been successfully developed. The developed ECD possesses the advantage of high optical switching speed (coloring transition time 22 s, bleaching transition time 1 s) for the application of back mirror. The coloration process of WO 3 was dramatically improved by addition of HNO 3 in the liquid PC+LiClO 4 electrolyte. The added HNO 3 generates larger quantities of H + ions which shuttle the WO 3 film fast because of its quite light mass increasing the color center to speedup the coloration process. Hence the developed method is available for improving optical switching speed of the ECD.

Separation of ions in acidic conditions using NF

The retention of Na + and Mg 2+ ions in their nitrate solutions was studied in the pH range 0.5–7. Three different Mg 2+ concentrations were used. Two nanofiltration membranes (NF 45 and Desal-5 DK) were tested. The NF 45 membrane showed higher retention values for the tested ions. The Mg 2+ ions were very well retained (97.5–99.5%) within the pH range. The nitric acid permeated freely in all of the experiments. The experiments showed that the concentration of nitric acid in the permeate depended on the ratio of H + ions/rejected metal ions in the feed. The retention of the Na + ion varied from 80–40%. The smallest Na + retention was measured in neutral conditions. The addition of HNO 3 led to a sharp increase in the Na + retention mostly because of two things: An increase in H + concentration (a cation that permeates more easily than the Na + ion) and the positive charge of the membrane due to the decrease in pH, increasing the rejection of all cations. In addition, the Na + retention decreased with an increase of the Mg 2+ concentration in the feed. The effect diminished gradually with decreasing pH due to a high ion concentration that lessened the charge effect of the membrane.

Studies on dislocation etching kinetics of flux-grown YFeO 3 crystals

Results of etching (110) and (001) planes of YFeO 3 crystals are presented and discussed in detail. It is shown that boiling H 3PO 4 or H 3PO 4+HNO 3 in the ratio of 1:1 is the dislocation etchant of YFeO 3 crystals. It is established that the latter etchant is best suited for both (110) and (001) planes insofar as the definition of pit and control over etching are concerned. The kinetics of etching are investigated by making a quantitative study of the etch rate at different temperatures and at different concentrations of H 3PO 4. Variations in areal extension and depth of pits with time in H 3PO 4 or H 3PO 4 mixed with HNO 3 are investigated. It is shown that the areal and vertical etch rates increase with increase in temperature on both (110) and (001) planes. Addition of HNO 3 to H 3PO 4 brings down the minimum temperature required for etching (110) and (001) planes. The velocities of dissolution parallel and perpendicular to the surface are measured. The activation energy responsible for the dislocation sites for dissolution parallel and perpendicular to (110) and (001) planes are estimated. The Arrhenius factors for areal ( A' A ) and vertical ( A D ) dissolution are A' A =1.44×10 9 and 3.99×10 7 μm/s, and A D =8.12×10 3 and 1.31×10 4 μm/s for (110) and (001) planes, respectively.

The effects of pH on the release to solution of zinc, copper and nickel from metal-loaded sewage sludges

The release of metal from four experimental sludges was studied as the pH of sludge-water suspensions was varied by addition of HNO 3 or KOH. The concentration of metal released from the sludge to the supernatant liquid increased as pH decreased below a threshold value, which was about 5·8 for zinc-loaded sludge, 6·3 for nickel-loaded sludge and 4·5 for copper-loaded sludge. Above these values the metal content of the supernatant was small and relatively constant. In speciation experiments the proportion of soluble copper present as Cu 2+ in CaCl 2 solution was related to pH ( r = − 0·97), whereas the proportion of soluble zinc present as Zn 2+ was scarcely correlated with pH ( r = 0·09).

A study of background signals in graphite-furnace atomic absorption spectrometry

The non-specific absorption from inorganic and organic molecules between 190 and 400 nm are measured using a graphite furnace and an atomic absorption spectrometer with a deuterium source. The molecular absorption spectra of NaCl, KCl, RbCl and CsCl are very similar, with two maxima at ca. 200 and 250 nm. That of LiCl is very weak, as is that of NaF. The spectra of NaBr, NaI, KBr, KI, CaCl 2, MgCl 2, SrCl 2, FeCl 3, LaCl 3 are also reported. The non-specific absorption spectrum arising from albumin decreases fro 190 to 400 nm, and that for plasma is similar to albumin, although a contribution from inorganic salts can also be seen. To decrease the non-specific absorption from metal chlorides or biological samples of mainly inorganic composition such as urine, addition of HNO 3 is satisfactory. Oxygen introduction during low temperature charring is better for removing contribution from organic molecules.

Photosynthetic and respiratory consequences of hydrogen chloride gas exposures of Phaseolus vulgaris L. and Spinacea oleracea L.

The effects of supra-acute exposure to gaseous HCl on Phaseolus vulgaris L. and Spinacea oleracea L. have been examined with respect to chlorophyll, ultrastructure, photosynthesis, respiration and RubPCase activity. Changes in ultrastructure and chlorophyll levels were noted in HCl-exposed plants. Photosynthetic and respiratory rates of leaf discs sampled from treated plants were: reduced directly proportional to the severity of injury; more depressed following HCl exposure than 24 h after exposure and enhanced in plants which exhibited minimal or no visual necrosis injury. Similar results were obtained using isolated chloroplasts. The rate of photosynthesis in chloroplasts isolated from spinach was shown to decrease with increasing incubation medium acidity resulting from the addition of HNO 3, H 2SO 4 or HCl. Enzyme extracts from control and HCl-exposed Phaseolus vulgaris L. were prepared and RubPCase was measured. Enzyme activity was stimulated in plants sustaining little or no visual injury and was depressed as either injury or concentration of HCl increased. Results suggest that exposure to HCl causes tissue acidification.

Anwendbarkeit der Zeeman-Effekt/Atomabsorption in der Komplexchemie und Spurenanalyse

The compensation of non specific background absorption is the main problem connected with determinations of traces of metals in the presence of large amounts of concomitants which volatilize together with the metal to be determined. This analytical problem manifests itself especially in flameless atomic absorption spectrometry used in coordination chemistry and trace analysis and can be very effectively mastered by the use of the Zeeman-effect atomic absorption spectrometry. This method works very well in the presence of 0.1 m KNO 3 or NAClO 4, where the most commonly used method, the deuterium background compensation, fails at this concentration of supporting electrolytes in most cases. The high compensating power of the Zeeman-effect method is also demonstrated by the determination of mercury in urine after a simple matrix modification by addition of HNO 3, Br 2 and KBr. The mechanism of the stabilization of mercury by this matrix modification is also discussed. The deuterium system failed in these determinations.

The effect of ammonium thiocyanate and sodium chloride on loss and recovery of mercury from water during storage

The effect of inorganic complexing agents such as thiocyanate and chloride on the stability of distilled water and natural waters spiked with 1 μg Hg l -1 in polyethylene containers is reported. Distilled water solutions can be stored for several months without significant losses of mercury if they contain HNO 3(0.05–0.1 M) + NH 4SCN(0.001–0.01 M) or HNO 3(0.1 M) + NaCl(higher than 0.01 M). For river and pond waters, addition of HNO 3(0.1 M) + NH 4SCN(0.01 M) not only has a pronounced effect on preventing mercury losses, but also gives quantitative recoveries from spiked sample solutions from which mercury has been “lost”. Thiocyanate ion-favors desorption of mercury from solid phases; chloride is less effective in this respect.