Kinetics and mechanism of oxidation of creatine by N-Bromosuccinimide in acidic aqueous medium

The kinetics and the mechanism of oxidation of creatine (AA) by N-Bromosuccinimide (NBS) in an acidic aqueous medium were examined under isolation conditions. Iodometric method was used to follow the unconsumed NBS at different time intervals. Mercuric(II) acetate was used as a scavenger to capture any Br- formed during the reaction and hence to avoid autocatalytic oxidation by bromine. Findings from stoichiometry measurements revealed that the reaction between AA and NBS was a 2:1 molar ratio. The kinetic study showed that the reaction was first order with respect to both AA and NBS. Increasing [H+] had a negative effect on the rate of reaction. The effect that varying the solvent composition has on the rate of reaction was investigated, and it was found that the reaction rate decreased as the dielectric constant of the solvent increased. The temperature dependence was determined under fixed experimental conditions, from which thermodynamic parameters were calculated. From the proposed mechanism, a rate law was established that was in strong agreement with experimental kinetics.

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Effects of serpentinite fertilizer on the chemical properties and enzyme activity of young spruce soils

International Agrophysics ◽

10.1515/intag-2016-0015 ◽

2016 ◽

Vol 30 (4) ◽

pp. 401-414 ◽

Cited By ~ 2

Author(s):

Ewa Błońska ◽

Kazimierz Januszek ◽

Stanisław Małek ◽

Tomasz Wanic

Keyword(s):

Enzyme Activity ◽

Chemical Properties ◽

Molar Ratio ◽

Tree Roots ◽

Forest Zone ◽

Negative Effect ◽

Phosphorus And Potassium ◽

One Year ◽

Nitrogen Phosphorus ◽

Experimental Plots

AbstractThe experimental plots used in the study were located in the middle forest zone (elevation: 900-950 m a.s.l.) on two nappes of the flysch Carpathians in southern Poland. The aim of this study was to assess the effects of serpentinite in combination with nitrogen, phosphorus, and potassium fertilizers on selected chemical properties of the soil and activity of dehydrogenase and urease in the studied soils. All fertilizer treatments significantly enriched the tested soils in magnesium. The use of serpentinite as a fertilizer reduced the molar ratio of exchangeable calcium to magnesium, which facilitated the uptake of magnesium by tree roots due to competition between calcium and magnesium. After one year of fertilization on the Wisła experimental plot, the pH of the Ofh horizon increased, while the pH of the mineral horizons significantly decreased. Enrichment of serpentinite with nitrogen, phosphorus, and potassium fertilizers stimulated the dehydrogenase activity in the studied organic horizon. The lack of a negative effect of the serpentinite fertilizer on enzyme activity in the spruce stand soil showed that the concentrations of the heavy metals added to the soil were not high enough to be toxic and indicated the feasibility of using this fertilizer in forestry.

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Grafting of (3-Chloropropyl)-Trimethoxy Silane on Halloysite Nanotubes Surface

Applied Sciences ◽

10.3390/app11125534 ◽

2021 ◽

Vol 11 (12) ◽

pp. 5534

Author(s):

Asmaa M. Abu El-Soad ◽

Giuseppe Lazzara ◽

Alexander V. Pestov ◽

Daria P. Tambasova ◽

Denis O. Antonov ◽

...

Keyword(s):

Active Site ◽

Chemical Engineering ◽

Coupling Reaction ◽

Ammonium Hydroxide ◽

Halloysite Nanotubes ◽

Chemical Activity ◽

Molar Ratio ◽

New Materials ◽

Experimental Conditions ◽

Trimethoxy Silane

Modified halloysite nanotubes (HNTs-Cl) were synthesized by a coupling reaction with (3-chloropropyl) trimethoxysilane (CPTMS). The incorporation of chloro-silane onto HNTs surface creates HNTs-Cl, which has great chemical activity and is considered a good candidate as an active site that reacts with other active molecules in order to create new materials with great applications in chemical engineering and nanotechnology. The value of this work lies in the fact that improving the degree of grafting of chloro-silane onto the HNT’s surface has been accomplished by incorporation of HNTs with CPTMS under different experimental conditions. Many parameters, such as the dispersing media, the molar ratio of HNTs/CPTMS/H2O, refluxing time, and the type of catalyst were studied. The greatest degree of grafting was accomplished by using toluene as a medium for the grafting process, with a molar ratio of HNTs/CPTMS/H2O of 1:1:3, and a refluxing time of 4 h. The addition of 7.169 mmol of triethylamine (Et3N) and 25.97 mmol of ammonium hydroxide (NH4OH) led to an increase in the degree of grafting of CPTMS onto the HNT’s surface.

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Photocatalytic Treatment of Wastewater Containing Simultaneous Organic and Inorganic Pollution: Competition and Operating Parameters Effects

Catalysts ◽

10.3390/catal11070855 ◽

2021 ◽

Vol 11 (7) ◽

pp. 855

Author(s):

Ahmed Amine Azzaz ◽

Salah Jellali ◽

Nasser Ben Harharah Hamed ◽

Atef El Jery ◽

Lotfi Khezami ◽

...

Keyword(s):

Ultra Violet ◽

Degradation Process ◽

Molar Ratio ◽

Experimental Conditions ◽

Retention Capacity ◽

Isotherm Study ◽

Related Data ◽

Ph Values ◽

Pseudo Second Order ◽

Maximum Retention

In the present study, methylene blue (MB) removal from aqueous solutions via the photocatalytic process using TiO2 as a catalyst in the presence of external ultra-violet light (UV) was investigated. The results of adsorption in the absence of UV radiation showed that adsorption reached an equilibrium state at 60 min. The experimental kinetic data were found to be well fitted by the pseudo-second-order model. Furthermore, the isotherm study suggested that dye uptake by TiO2 is a chemisorption process with a maximum retention capacity of 34.0 mg/g. The photodegradation of MB was then assessed under various experimental conditions. The related data showed that dye mineralization decreased when dye concentrations were increased and was favored at high pH values and low salt concentrations. The simultaneous presence of organic and inorganic pollution (Zinc) was also evaluated. The effect of the molar ratio Zn2+/MB+ in the solution at different pH values and NaCl concentrations was also monitored. The corresponding experimental results showed that at low values of Zn2+ in the solution (30 mg/L), the kinetic of the MB removal became faster until reaching an optimum at Zn2+/MB+ concentrations of 60/60 mg/L; it then slowed down for higher concentrations. The solutions’ carbon contents were measured during the degradation process and showed total mineralization after about 5 h for the optimal Zn2+/MB+ condition.

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Gut Microbiota Dynamics in Natural Populations of Pintomyia evansi under Experimental Infection with Leishmania infantum

Microorganisms ◽

10.3390/microorganisms9061214 ◽

2021 ◽

Vol 9 (6) ◽

pp. 1214

Author(s):

Rafael José Vivero ◽

Victor Alfonso Castañeda-Monsalve ◽

Luis Roberto Romero ◽

Gregory D. Hurst ◽

Gloria Cadavid-Restrepo ◽

...

Keyword(s):

Gut Microbiota ◽

Leishmania Infantum ◽

Natural Populations ◽

Illumina Miseq ◽

Urban Environments ◽

High Load ◽

Leishmania Infection ◽

Experimental Conditions ◽

Rural And Urban ◽

Negative Effect

Pintomyia evansi is recognized by its vectorial competence in the transmission of parasites that cause fatal visceral leishmaniasis in rural and urban environments of the Caribbean coast of Colombia. The effect on and the variation of the gut microbiota in female P. evansi infected with Leishmania infantum were evaluated under experimental conditions using 16S rRNA Illumina MiSeq sequencing. In the coinfection assay with L. infantum, 96.8% of the midgut microbial population was composed mainly of Proteobacteria (71.0%), followed by Cyanobacteria (20.4%), Actinobacteria (2.7%), and Firmicutes (2.7%). In insect controls (uninfected with L. infantum) that were treated or not with antibiotics, Ralstonia was reported to have high relative abundance (55.1–64.8%), in contrast to guts with a high load of infection from L. infantum (23.4–35.9%). ASVs that moderately increased in guts infected with Leishmania were Bacillus and Aeromonas. Kruskal–Wallis nonparametric variance statistical inference showed statistically significant intergroup differences in the guts of P. evansi infected and uninfected with L. infantum (p < 0.05), suggesting that some individuals of the microbiota could induce or restrict Leishmania infection. This assay also showed a negative effect of the antibiotic treatment and L. infantum infection on the gut microbiota diversity. Endosymbionts, such as Microsporidia infections (<2%), were more often associated with guts without Leishmania infection, whereas Arsenophonus was only found in guts with a high load of Leishmania infection and treated with antibiotics. Finally, this is the first report that showed the potential role of intestinal microbiota in natural populations of P. evansi in susceptibility to L. infantum infection.

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Reaktive E=C(p–p)π Systeme, XXXIV Addition von Alkoholen oder primären Aminen an Phosphaalkene F3CP=C(F)OR. Neue Trifluormethylphosphane und -phosphaalkene/Reactive E = C( p – p ) π-Systems, XXXIV Addition of Alcohols or Primary Amines to Phosphaalkenes F3CP= C(F)OR . Novel Trifluoromethylphosphanes and Phosphaalkenes

Zeitschrift für Naturforschung B ◽

10.1515/znb-1993-0114 ◽

1993 ◽

Vol 48 (1) ◽

pp. 58-67 ◽

Cited By ~ 10

Author(s):

Joseph Grobe ◽

Duc Le Van ◽

Gudrun Lange

Keyword(s):

High Resolution Mass Spectrometry ◽

Molar Ratio ◽

Primary Amines ◽

The Novel ◽

Experimental Conditions ◽

Pull System ◽

Fragment Ions ◽

New Compounds ◽

C Nmr

The course of the reactions o f fluorophosphaalkenes F3CP = C (F)OR [R = Me (1), Et (2)] with methanol or ethanol strongly depends on the experimental conditions. Thus at 70 °C a mixture of the 2-phosphapropionic acid ester F3CP (H )CO2R [R = Me (3), Et (4)] and trifluoromethylphosphane H2PCF3 is formed [molar ratio: 3 or 4 /H2 CF3 ≈1/1]. If the precursors F3CP (H )CO2R [R = Me (3), Et) are used as starting materials, the reaction with ROH under the same conditions affords 3 and 4, respectively, (90 to 95% yield) with only traces of H2PCF 3. In the presence o f iPr2NH these precursors react with R′OH to give the novel trifluoromethylphosphaalkenes F3CP = C (OR )OR [R /R′: Me/Me (6); E t/E t (7); Me/Et (8)]. With Et2NH , 3 undergoes an addition/elimination process yielding the interesting push/pull system Et2N(F)C = P-CO2Me (5). 1 and 2 react with primary amines R′NH2 (R′= tBu, Me) with stereoselective formation of the fairly labile phosphaalkenes F3CP = C(OR)NHR′ [R /R′: Me/tBu (9), Et/tBu(10), Me/Me (11)] with trans-positions for CF3 and NHR′.The new compounds 3 -11 were characterized by spectroscopic investigations (1H , 19F, 31P, 13C NMR ; IR, MS) and determination of M+ or typical fragment ions [M+ -OR ] by high resolution mass spectrometry.

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Comparison of Bite Force in Patients After Treatment of Mandibular Fractures With 3-Dimensional Locking Miniplate and Standard Miniplates

The Traumaxilla ◽

10.1177/2632327319881058 ◽

2019 ◽

Vol 1 (1) ◽

pp. 7-10

Author(s):

Gaurav Singh ◽

Madan Mishra ◽

Amit Gaur ◽

Dhritiman Pathak

Keyword(s):

Treatment Strategies ◽

Bite Force ◽

Mandibular Fractures ◽

Time Intervals ◽

Experimental Conditions ◽

3 Dimensional ◽

The Mean ◽

Group 2 ◽

Drilling Conditions ◽

Group 1

Background: Fractures of the mandible can be studied and described in anatomic terms, functional considerations, treatment strategies, and outcome measures. The performance of any fixation system depends on multiple factors including plate adaptation, screw placement, bone quality, drilling conditions, and postoperative patient compliance. Bite force assesses masticatory muscle function under clinical and experimental conditions. Method: 30 patients with isolated, noncomminuted mandibular fractures were randomly divided into two equal groups. Group 1 patients were treated using 3-dimensional locking miniplates and group 2 patients were treated with standard miniplates. The bite forces were recorded at definite time intervals: preoperatively, and second week, sixth week, third month, and sixth month postoperatively. Result: At 6 weeks postoperative, 3 month postoperative, and 6 month postoperative, the mean bite force was found to be significantly higher among group 1 patients as compared to those in group 2 in all the sites. While at 2 week postoperative, the mean bite force was found to be significantly higher in Group 2 as compared to Group 1 at incisor region. Conclusion: The overall results of the present study show better performance in bite force for the 3-dimensional locking miniplate when compared with standard miniplates.

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Phosphorus extracted by ion exchange resins and mehlich-1 from oxisols (latosols) treated with different phosphorus rates and sources for varied soil-source contact periods

Revista Brasileira de Ciência do Solo ◽

10.1590/s0100-06832013000300013 ◽

2013 ◽

Vol 37 (3) ◽

pp. 667-677 ◽

Cited By ~ 17

Author(s):

Irio Fernando de Freitas ◽

Roberto Ferreira Novais ◽

Ecila Mercês de Albuquerque Villani ◽

Sarah Vieira Novais

Keyword(s):

Sandy Loam ◽

Extraction Methods ◽

Available P ◽

Molar Ratio ◽

P Availability ◽

Triple Superphosphate ◽

Experimental Conditions ◽

Reactive Phosphate ◽

Exchange Resins ◽

P Sources

Despite the large number of studies addressing the quantification of phosphorus (P) availability by different extraction methods, many questions remain unanswered. The aim of this paper was to compare the effectiveness of the extractors Mehlich-1, Anionic Resin (AR) and Mixed Resin (MR), to determine the availability of P under different experimental conditions. The laboratory study was arranged in randomized blocks in a [(3 x 3 x 2) + 3] x 4 factorial design, with four replications, testing the response of three soils with different texture: a very clayey Red Latosol (LV), a sandy clay loam Red Yellow Latosol (LVA), and a sandy loam Yellow Latosol (LA), to three sources (triple superphosphate, reactive phosphate rock from Gafsa-Tunisia; and natural phosphate from Araxá-Minas Gerais) at two P rates (75 and 150 mg dm-3), plus three control treatments (each soil without P application) after four contact periods (15, 30, 60, and 120 days) of the P sources with soil. The soil acidity of LV and LVA was adjusted by raising base saturation to 60 % with the application of CaCO3 and MgCO3 at a 4:1 molar ratio (LA required no correction). These samples were maintained at field moisture capacity for 30 days. After the contact periods, the samples were collected to quantify the available P concentrations by the three extractants. In general, all three indicated that the available P-content in soils was reduced after longer contact periods with the P sources. Of the three sources, this reduction was most pronounced for triple superphosphate, intermediate for reactive phosphate, while Araxá phosphate was least sensitive to the effect of time. It was observed that AR extracted lower P levels from all three soils when the sources were phosphate rocks, while MR extracted values close to Mehlich-1 in LV (clay) and LVA (medium texture) for reactive phosphate. For Araxá phosphate, much higher P values were determined by Mehlich-1 than by the resins, because of the acidity of the extractor. For triple superphosphate, both resins extracted higher P levels than Mehlich-1, due to the consumption of this extractor, particularly when used for LV and LVA.

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Treatability of textile dye-bath effluents by advanced oxidation: preparation for reuse

Water Science & Technology ◽

10.2166/wst.1999.0040 ◽

1999 ◽

Vol 40 (1) ◽

pp. 183-190 ◽

Cited By ~ 30

Author(s):

N. H. Ince ◽

G. Tezcanlı

Keyword(s):

Organic Carbon ◽

Total Organic Carbon ◽

Azo Dye ◽

Uv Light ◽

Advanced Oxidation ◽

Membrane System ◽

Molar Ratio ◽

Textile Dye ◽

Experimental Conditions ◽

Solids Content

Treatability of textile dye-bath effluents by advanced oxidation with Fenton and Fenton-like reagents (FeII/H2O2 and FeIII/H2O2), in the presence and absence of UV light was investigated, using a reactive azo-dye (Procion Red HE7B), and typical dye bath constituents. Under the experimental conditions employed, it was found that with 20 min UV irradiation, complete color removal and 79% total organic carbon degradation is possible, when the system is operated at pH=3, and with a H2O2/Fe(II) molar ratio of 20:1. The increased dissolved solids content of the treated solution implies the necessity of an appropriate membrane system to make the effluent reusable in the dye/wash processes.

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Esterification of palmitic acid with epichlorohydrin on anion exchange resin catalyst

Open Chemistry ◽

10.2478/s11532-007-0033-9 ◽

2007 ◽

Vol 5 (3) ◽

pp. 715-726 ◽

Cited By ~ 2

Author(s):

Emil Muresan ◽

Spiridon Oprea ◽

Theodor Malutan ◽

Mihai Vata

Keyword(s):

Palmitic Acid ◽

Exchange Resin ◽

Catalyst Particle ◽

Molar Ratio ◽

Catalyst Loading ◽

Esterification Reaction ◽

Macroporous Resin ◽

Resin Catalyst ◽

Catalyst Particle Size ◽

Rate Of Reaction

AbstractThe esterification reaction of palmitic acid with epichlorohydrin catalyzed by an anionic macroporous resin was studied. Purolite A-500 resin proved to be a very effective catalyst in the synthesis of 3-chloro-2-hydroxypropyl palmitate. The effects of certain parameters such as speed of agitation, catalyst particle size, catalyst loading, temperature, initial molar ratio between reactants on the rate of reaction were studied. It was found that the overall rate is intrinsically kinetically controlled. The structure of synthesized ester was confirmed by FTIR and 1H NMR analyses.

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Optimization Preparation of Indium Tin Oxide Nanoparticles via Microemulsion Method Using Orthogonal Experiment

Crystals ◽

10.3390/cryst11111387 ◽

2021 ◽

Vol 11 (11) ◽

pp. 1387

Author(s):

Zhucheng Jiang ◽

Ting Liu ◽

Xiaoyu Zhai ◽

Jiaxiang Liu

Keyword(s):

Calcination Temperature ◽

Tin Oxide ◽

Indium Tin Oxide ◽

Orthogonal Experiment ◽

Transparent Conducting Oxide ◽

Molar Ratio ◽

Experimental Conditions ◽

Microemulsion Method ◽

Low Resistivity ◽

Ito Nanoparticles

Indium tin oxide (ITO), an experimentally friendly transparent conducting oxide (TCO), has attracted great attention in the photoelectric field due to its intrinsically low resistivity and high transparency. In this work, the experimental conditions of preparing ITO nanoparticles using the microemulsion method were optimized by an orthogonal experiment. The optimal experimental conditions were obtained: mass ratio of the surfactant (AEO-3, MOA-5), a co-surfactant (n-propyl alcohol) of 5:3, molar ratio of indium and ammonia of 1:20, calcination temperature of 700 °C and calcination time of 4 h. Subsequently, the influence from process variables on the resistivity was researched systematically. The results demonstrated that the calcination temperature had a great effect on the resistivity; the resistivity reduced from 11.28 to 2.72 Ω·cm with the increase in the calcination temperature from 500 to 700 °C. Ultimately, ITO nanoparticles were prepared and systematically characterized under the optimal experimental conditions. The particles with a size of 60 nm were attributed to the cubic ITO crystal phase and showed low resistivity of 0.3675 Ω·cm. Significantly, ITO nanoparticles with low resistivity were obtained using the microemulsion method, which has potential application in the field of ITO nanoparticle preparation.

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