scholarly journals Сitric acid influence on electroreduction processes in low concentrated Cu(NO3)2 solutions

2017 ◽  
Vol 5 (2) ◽  
pp. 136-143
Author(s):  
Alla Pravda ◽  
Vasil Larin

Physico-chemical regularities citric acid influence on processes of copper and nitrate-ions reduction in low concentrated nitrate solutions were established. An influence of pH value on inhibitor action of low concentrations of the additive according to cathode reduction reaction of nitrate-ions, on kinetics of copper electrodeposition, on structure of the precipitates obtained was shown. Polarization measurements show us changes of copper electrodeposition at introduction of citric acid in Cu(NO3)2 solution. By the methods of traced elements and extraction into aqueous phase the reversible inclusion complexes into electrolytic copper, was established that proves participation of complexes in cathode process.

Author(s):  
Anderson dos Santos Formiga ◽  
Franciscleudo Bezerra da Costa ◽  
Marcio Santos da Silva ◽  
Emmanuel Moreira Pereira ◽  
Yasmin Lima Brasil

<p>O objetivo do trabalho foi disponibilizar informações sobre os aspectos tecnológicos e nutricionais dos frutos do quipá buscando aplicações para o mesmo na alimentação humana. O quipá é uma planta nativa da região Nordeste, seus frutos, ao contrário do figo-da-índia não é valorizado. Os frutos foram colhidos, acondicionados e conduzidos ao laboratório de Análise de Alimentos, CCTA/UFCG, Pombal-PB. Em seguida foram divididos em quatro lotes e submetidos à extração da polpa. Foram avaliadas as características físicas, físico-químicas e químicas dos frutos do quipá. Os frutos são pequenos, a casca representa mais da metade do peso do fruto e com as sementes dificultam a aceitabilidade dos frutos pelo consumidor. A polpa compõe pouco mais de 20% do peso do fruto, possui pH ácido, com baixa concentração de ácido cítrico e sólidos solúveis inferiores aos frutos de figo-da-índia e do mandacaru, comuns ao semiárido; as concentrações de vitamina C e compostos fenólicos na polpa foram consideradas significativas, o que não ocorreu com os flavonoides e antocianinas, que estavam presentes em baixas concentrações.</p><p align="center"><strong><em>Physical and chemical aspects of fruit Quipá (Tacinga inamoena)</em></strong></p><p><strong>Abstract</strong><strong>: </strong>The objective was to provide information on the technological and nutritional aspects of the fruits of Quipá in order to seek applications for the same in human nutrition. The Quipá is a plant native to the Northeast, its fruit, unlike the fig-of-India is not valued. The fruits were harvested, packaged and taken to the Food Analysis Laboratory, CCTA / UFCG, Pombal-PB. They were then divided into four batches and subjected to extraction of the pulp. the physical, physico-chemical and chemical of the fruits of Quipá were evaluated. The fruits are small, the shell is more than half the weight of the fruit and seeds hinder the acceptability of fruit by the consumer. The pulp makes up just over 20% of the fruit weight, has an acidic pH, with low concentration of citric acid soluble solids and lower the fruit of fig-of-India and mandacaru common to semiarid; concentrations of vitamin C and phenolic compounds were considered significant, which did not occur with the flavonoids and anthocyanins, which were present in low concentrations.</p>


1977 ◽  
Vol 16 (04) ◽  
pp. 157-162 ◽  
Author(s):  
C. Schümichen ◽  
B. Mackenbrock ◽  
G. Hoffmann

SummaryThe bone-seeking 99mTc-Sn-pyrophosphate compound (compound A) was diluted both in vitro and in vivo and proved to be unstable both in vitro and in vivo. However, stability was much better in vivo than in vitro and thus the in vitro stability of compound A after dilution in various mediums could be followed up by a consecutive evaluation of the in vivo distribution in the rat. After dilution in neutral normal saline compound A is metastable and after a short half-life it is transformed into the other 99mTc-Sn-pyrophosphate compound A is metastable and after a short half-life in bone but in the kidneys. After dilution in normal saline of low pH and in buffering solutions the stability of compound A is increased. In human plasma compound A is relatively stable but not in plasma water. When compound B is formed in a buffering solution, uptake in the kidneys and excretion in urine is lowered and blood concentration increased.It is assumed that the association of protons to compound A will increase its stability at low concentrations while that to compound B will lead to a strong protein bond in plasma. It is concluded that compound A will not be stable in vivo because of a lack of stability in the extravascular space, and that the protein bond in plasma will be a measure of its in vivo stability.


1977 ◽  
Vol 16 (01) ◽  
pp. 30-35 ◽  
Author(s):  
N. Agha ◽  
R. B. R. Persson

SummaryGelchromatography column scanning has been used to study the fractions of 99mTc-pertechnetate, 99mTcchelate and reduced hydrolyzed 99mTc in preparations of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn). The labelling yield of 99mTc-EDTA(Sn) chelate was as high as 90—95% when 100 μmol EDTA · H4 and 0.5 (Amol SnCl2 was incubated with 10 ml 99mTceluate for 30—60 min at room temperature. The study of the influence of the pH-value on the fraction of 99mTc-EDTA shows that pH 2.8—2.9 gave the best labelling yield. In a comparative study of the labelling kinetics of 99mTc-EDTA(Sn) and 99mTc- DTPA(Sn) at different temperatures (7, 22 and 37°C), no significant influence on the reduction step was found. The rate constant for complex formation, however, increased more rapidly with increased temperature for 99mTc-DTPA(Sn). At room temperature only a few minutes was required to achieve a high labelling yield with 99mTc-DTPA(Sn) whereas about 60 min was required for 99mTc-EDTA(Sn). Comparative biokinetic studies in rabbits showed that the maximum activity in kidneys is achieved after 12 min with 99mTc-EDTA(Sn) but already after 6 min with 99mTc-DTPA(Sn). The long-term disappearance of 99mTc-DTPA(Sn) from the kidneys is about five times faster than that for 99mTc-EDTA(Sn).


2020 ◽  
pp. 6-11
Author(s):  
Anton Kasatkin ◽  
Anna Nigmatullina ◽  
Mikhail Kopytov

The article presents the results of studies of osmolality and pH of 0,9 % sodium chloride of various manufacturers. To obtain data on the pH value, the data used in the passports are used, and the indicators of its osmolality are de- termined using laboratory tests. 0,9 % sodium chloride from different manufacturers has different pH and osmolality. Knowing the actual values of physico-chemical parameters can increase the accuracy of the results of future clinical studies, which compare the pharmacokinetics and pharmacodynamics of modern plasma-substituting solutions and a solution of 0,9 % sodium chloride.


2013 ◽  
Vol 28 (4) ◽  
pp. 387-392
Author(s):  
Tong SUN ◽  
Lian-Li LIU ◽  
Shu-Ying XU ◽  
Xiao-Lin PENG ◽  
Hai-Long YANG

1994 ◽  
Vol 30 (11) ◽  
pp. 143-146
Author(s):  
Ronald D. Neufeld ◽  
Christopher A. Badali ◽  
Dennis Powers ◽  
Christopher Carson

A two step operation is proposed for the biodegradation of low concentrations (&lt; 10 mg/L) of BETX substances in an up flow submerged biotower configuration. Step 1 involves growth of a lush biofilm using benzoic acid in a batch mode. Step 2 involves a longer term biological transformation of BETX. Kinetics of biotransformations are modeled using first order assumptions, with rate constants being a function of benzoic acid dosages used in Step 1. A calibrated computer model is developed and presented to predict the degree of transformation and biomass level throughout the tower under a variety of inlet and design operational conditions.


1980 ◽  
Vol 45 (3) ◽  
pp. 783-790 ◽  
Author(s):  
Petr Taras ◽  
Milan Pospíšil

Catalytic activity of nickel-molybdenum catalysts for methanation of carbon monoxide and hydrogen was studied by means of differential scanning calorimetry. The activity of NiMoOx systems exceeds that of carrier-free nickel if x < 2, and is conditioned by the oxidation degree of molybdenum, changing in dependence on the composition in the region Mo-MoO2. The activity of the catalysts is adversely affected by irradiation by fast neutrons, dose 28.1 Gy, or by γ rays using doses in the region 0.8-52 kGy. The system is most susceptible to irradiation in the region of low concentrations of the minor component (about 1 mol.%). The dependence of changes in catalytic activity of γ-irradiated samples on the dose exhibits a maximum in the range of 2-5 kGy. The changes in catalytic activity are stimulated by the change of reactivity of the starting mixed oxides, leading to different kinetics of their reduction and modification of their adsorption properties. The irradiation of the catalysts results in lowered concentration of the active centres for the methanation reaction.


1986 ◽  
Vol 51 (10) ◽  
pp. 2098-2108 ◽  
Author(s):  
Milan Pospíšil ◽  
Jan Topinka

We investigated the effect of origin and some physico-chemical parameters on the kinetics of reduction with hydrogen of two series of mixed NiO-Fe2O3 oxides differing by their composition, the character of their precursors (mixed crystalline nitrates and coprecipitated hydroxides) and their decomposition temperature.This effect manifested itself by different magnitudes of specific surfaces of the mixed oxides and coherent regions of present phases as well as by different oxidizing abilities of the surface and differences in morphology and phase composition of corresponding samples in both series investigated. Nonlinear or nonmonotonous composition dependences of physico-chemical parameters investigated point to a mutual influence of individual components, which is also a function of the system origin and which modifies its reactivity during its reduction with hydrogen. The kinetics of the reduction was studied thermogravimetrically at 320-410 °C. The reduction of oxides of the hydroxide origin is catalytically accelerated by primarily reduced nickel, whereas in corresponding samples of the nitrate series, the total NiO is bound to the spinel phase and the reduction is delayed. Experimental IR spectra, the effect of preliminary annealing and DTA of the mixed oxides point to an inhibitory effect of water, which is constitutionally bound in trace admixtures of the goethite phase, on the kinetics of reduction of samples in the hydroxide series.


Antibiotics ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 709
Author(s):  
Marta Jorba ◽  
Marina Pedrola ◽  
Ouldouz Ghashghaei ◽  
Rocío Herráez ◽  
Lluis Campos-Vicens ◽  
...  

This work reports a detailed characterization of the antimicrobial profile of two trimethoprim-like molecules (compounds 1a and 1b) identified in previous studies. Both molecules displayed remarkable antimicrobial activity, particularly when combined with sulfamethoxazole. In disk diffusion assays on Petri dishes, compounds 1a and 1b showed synergistic effects with colistin. Specifically, in combinations with low concentrations of colistin, very large increases in the activities of compounds 1a and 1b were determined, as demonstrated by alterations in the kinetics of bacterial growth despite only slight changes in the fractional inhibitory concentration index. The effect of colistin may be to increase the rate of antibiotic entry while reducing efflux pump activity. Compounds 1a and 1b were susceptible to extrusion by efflux pumps, whereas the inhibitor phenylalanine arginyl β-naphthylamide (PAβN) exerted effects similar to those of colistin. The interactions between the target enzyme (dihydrofolate reductase), the coenzyme nicotinamide adenine dinucleotide phosphate (NADPH), and the studied molecules were explored using enzymology tools and computational chemistry. A model based on docking results is reported.


2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Luqman Ali Shah ◽  
Rida Javed ◽  
Mohammad Siddiq ◽  
Iram BiBi ◽  
Ishrat Jamil ◽  
...  

AbstractThe in-situ stabilization of Ag nanoparticles is carried out by the use of reducing agent and synthesized three different types of hydrogen (anionic, cationic, and neutral) template. The morphology, constitution and thermal stability of the synthesized pure and Ag-entrapped hybrid hydrogels were efficiently confirmed using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and thermo gravimetric analysis (TGA). The prepared hybrid hydrogels were used in the decolorization of methylene blue (MB) and azo dyes congo red (CR), methyl Orange (MO), and reduction of 4-nitrophenol (4-NP) and nitrobenzene (NB) by an electron donor NaBH4. The kinetics of the reduction reaction was also assessed to determine the activation parameters. The hybrid hydrogen catalysts were recovered by filtration and used continuously up to six times with 98% conversion of pollutants without substantial loss in catalytic activity. It was observed that these types of hydrogel systems can be used for the conversion of pollutants from waste water into useful products.


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