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Potassium Nitrate (potassium + nitrate)
Selected AbstractsA new method of potassium chromate production from chromite and KOH-KNO3 -H2O binary submolten salt systemAICHE JOURNAL, Issue 10 2009Zhi Sun Abstract A new method of chromate production by applying a new reaction system of KOH-KNO3 -H2O (binary submolten salt system) is proposed and proved feasible. Under conditions of temperature 350°C, KOH-to-chromite ore ratio 2:1, stirring speed 700 rpm, KNO3 -to-chromite ore ratio 0.8:1, oxygen partial pressure 50%, and gas flow 1 L/min, chromium conversion ratio obtained is >98% with reaction time around 300 min. The decomposition of chromite ore in the system is a typical process of solid, liquid,gas reaction, which is coordinately controlled by mass diffusion in product layer and interface reaction. Apparent activation energy of decomposition in the temperature range from 280 to 370°C is 55.63 kJ/mol. During reaction, oxygen dissolves into KOH-KNO3 -H2O melt system first and some cluster, e.g. O, is formed and the mass diffusion coefficient of the cluster was calculated. The system can be considered as both a media of oxygen transportation and reactant donator. Potassium nitrate plays a role of catalyst in the oxidation decomposition reaction of chromite ore and potassium hydroxide. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] The use of toxicity bioassays to monitor the recovery of oiled wetland sedimentsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2003Danica C. Mueller Abstract Six toxicity assays were compared to determine their efficacy in assessing toxicity dynamics during a wetland bioremediation study. The toxicity bioassays used were the Microtox® 100% elutriate test, Microtox Solid Phase Test (SPT), amphipod assay, P450 reporter gene system, Toxi-ChromoPadÔ test and a Salmonella/microsome assay. Oiled sediments were analyzed for toxicity in the petroleum biostimulation experiment conducted along the San Jacinto River, near Houston (TX, USA). The bioassays were evaluated for their ability to measure acute toxicity, chronic toxicity, and the mutagenic potential of amended oiled plots as compared to oiled and unoiled control plots. Amendments were diammonium phosphate alone or in combination with potassium nitrate, which served as an alternate electron acceptor. With exception of the Toxi-ChromoPad and Salmonella tests, the bioassays exhibited a significant increase in toxicity after oil application. Microtox bioassays detected significant sediment toxicity up to 29 d after oil and amendment application. The Microtox solid phase test results correlated strongly with gas chromatographymass spectrometry analyses of total target saturate and aromatic hydrocarbons. The amphipod assay detected initial toxicity with a decline to day 70, followed by a significant increase in toxicity on day 140 in plots receiving nutrient amendments, which may be in response to excessive nutrient application. Low levels of enzyme induction were observed with the P450 reporter gene system assay in all oiled sediments throughout the study, suggesting low but persistent levels of polycyclic aromatic hydrocarbons. Of the six tests, the two Microtox tests and the amphipod test showed the most potential in evaluating petroleum toxicity in wetland sediments. [source] Desensitizing Agent Efficacy during Whitening in an At-Risk PopulationJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 1 2004RALPH H. LEONARD Jr. DDS. ABSTRACT Background: Nightguard vital bleaching (NGVB) has gained acceptance among dentists and patients as a simple and effective procedure to lighten discolored teeth. Although the efficacy and predictability of NGVB have been well established, it has been documented that patients undergoing the procedure may experience side effects such as tooth sensitivity (TS) and gingival irritation (GI). A previous NGVB study suggested that selected participants might benefit from a regimen of a desensitizing agent (DSA)to decrease or prevent TS during whitening. Purpose: The purpose of this study was to determine whether the daily use of an active DSA (UltraEZTM, Ultradent Products Inc., South Jordan, UT, USA) during NGVB would decrease TS in a population at risk for TS when compared with a placebo. Materials and Methods: Forty subjects participated in this single-blind randomized clinical trial. All participants had indicated that they had preexisting TS or other risk factors for TS during NGVB. To evaluate TS caused by the tray alone, participants wore custom-fitted maxillary whitening trays containing no DSA or whitening solution during week 1. Next, participants were randomly assigned to apply either the active DSA or placebo daily for 14 days in the trays for 30 minutes prior to whitening. The placebo was the same formulation as UltraEZ but without the desensitizing agents (3% potassium nitrate and 0.11% by weight fluoride ion). The bleaching solution was a 10% carbamide peroxide whitening solution (OpalescenceTM, Ultradent Inc.). Post treatment, participants were followed up for 1 week, during which time they used neither trays nor solutions. Throughout the study, participants completed a daily diary to record their perceptions of TS and the time spent wearing the tray with the whitening solution. Results: Forty-one percent of the active group had at least 1 day of TS during treatment compared with 78% of the placebo group. The difference was statistically significant (p= .027) using the two-tailed Fisher exact test. [source] AKIN,1 is Involved in the Regulation of Nitrogen Metabolism and Sugar Signaling in ArabidopsisJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 5 2009Xiao-Fang Li Abstract Sucrose non-fermenting-1-related protein kinase 1 (SnRK1) has been located at the heart of the control of metabolism and development in plants. The active SnRK1 form is usually a heterotrimeric complex. Subcellular localization and specific target of the SnRK1 kinase are regulated by specific beta subunits. In Arabidopsis, there are at least seven genes encoding beta subunits, of which the regulatory functions are not yet clear. Here, we tried to study the function of one beta subunit, AKIN,1. It showed that AKIN,1 expression was dramatically induced by ammonia nitrate but not potassium nitrate, and the investigation of AKIN,1 transgenic Arabidopsis and T-DNA insertion lines showed that AKIN,1 negatively regulated the activity of nitrate ruductase and was positively involved in sugar repression in early seedling development. Meanwhile AKIN,1 expression was reduced upon sugar treatment (including mannitol) and did not affect the activity of sucrose phosphate synthase. The results indicate that AKIN,1 is involved in the regulation of nitrogen metabolism and sugar signaling. [source] Seeded Crystallization of LeuciteJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 5 2007Yi Zhang The leucite crystallization kinetics from a hydrothermally derived precursor seeded with nano-crystalline leucite was investigated by X-ray diffraction and non-isothermal differential thermal analysis. The nano-crystalline leucite was prepared by high-energy milling of high-purity leucite powder and the leucite precursor was prepared by the hydrothermal method of silica sol, aluminum nitrate, and potassium nitrate. After the seeds were introduced, the crystallization temperature of the precursor was lowered by 100°C and the transition phase kalsilite did not appear during the crystallization process. When the seeded precursor was heat treated at 700°C, a small amount of cubic leucite was stabilized to room temperature. The seeded precursor showed an exothermic peak between 800° and 920°C under different heating rates. The activation energy for the growth of leucite from the seeded precursor was 256(SD9) kJ/mol. [source] Growth and single-crystal refinement of phase-III potassium nitrate, KNO3ACTA CRYSTALLOGRAPHICA SECTION B, Issue 6 2009Evelyn J. Freney Oriented single crystals of the high-temperature phase of KNO3 (phase III), a ferroelectric compound that may also occur as an atmospheric aerosol particle, were grown at room temperature and pressure by atomizing a solution of KNO3 in water and allowing droplets to dry on a glass substrate. The crystals are up to 1,mm across and are stable unless mechanically disturbed. There is no evidence of the spontaneous transformation of phase III to the room-temperature stable phase (phase II), even after several months. Single-crystal structure determinations of phase III were obtained at 295 and 123,K. The unit cell regained its room-temperature dimensions after warming from 123,K. The phase-III KNO3 structure can be viewed as the stacking parallel to the c axis of alternating K atoms and planar NO3 groups. The NO3 groups connect the planes of K atoms, where each O is fourfold coordinated to one N and three K. Each K atom has nine O nearest neighbors, with three bonds at 2.813 and six at 2.9092,Å. The interatomic K,N,K distance alternates from 5.051 to 3.941 along the c axis. The N,O distances increase from 1.245,(2),Å at 295,K to 1.2533,(15),Å at 123,K. The nitrate group has a slight non-planarity, with the N atoms 0.011,Å above the O plane and directed toward the more distant K of the K,N,K chain. [source] Control of purple spot of loquat fruit (Eriobotrya japonica) by means of mineral compoundsANNALS OF APPLIED BIOLOGY, Issue 4 2005N GARIGLIO Summary Treatments to control purple spot of loquat fruit (Eriobotrya japonica) were tested based on the hypothesis that the disorder appears as a consequence of water unbalance between flesh and epidermal tissues caused by their different ability for sugar accumulation. Calcium nitrate, calcium chloride, Ca-EDTA, ammonium nitrate and potassium nitrate at a concentration of 150 mm applied 2 weeks before fruit colour break reduced significantly the proportion of purple-spotted fruit, giving rise to a reduction of water potential of the epidermal tissue that allows it to retain water. The most favourable date of treatment was during the 2 weeks prior to fruit colour break. [source] | |||||||||||||