Acid Addition
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2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Matej Par ◽  
Andrea Gubler ◽  
Thomas Attin ◽  
Zrinka Tarle ◽  
Tobias T. Tauböck

AbstractThe aim of this study was to investigate whether experimental and commercial dental restorative materials with functional fillers can exert a protective anti-demineralizing effect on enamel that is not immediately adjacent to the restoration. Four experimental resin composites with bioactive glass and three commercial restorative materials were investigated. Enamel blocks were incubated in a lactic acid solution (pH = 4.0) at a standardized distance (5 mm) from cured specimens of restorative materials. The lactic acid solution was replenished every 4 days up to a total of 32 days. Surfaces of enamel blocks were periodically evaluated by Knoop microhardness measurements and scanning electron microscopy. The protective effect of restorative materials against acid was identified as enamel microhardness remaining unchanged for a certain number of 4-day acid addition cycles. Additionally, the pH of the immersion medium was measured. While enamel microhardness in the control group was maintained for 1 acid addition cycle (4 days), restorative materials postponed enamel softening for 2–5 cycles (8–20 days). The materials capable of exerting a stronger alkalizing effect provided longer-lasting enamel protection. The protective and alkalizing effects of experimental composites improved with higher amounts of bioactive glass and were better for conventional bioactive glass 45S5 compared to a fluoride-containing bioactive glass. Scanning electron micrographs evidenced the protective effect of restorative materials by showing a delayed appearance of an etching pattern on the enamel surface. A remotely-acting anti-demineralizing protective effect on enamel was identified in experimental composites functionalized with two types of bioactive glass, as well as in three commercial ion-releasing restorative materials.


Author(s):  
Zhongteng Bai ◽  
Yanqiu Wang ◽  
Mingjun Shan ◽  
Yanli Lv ◽  
Guangcai Meng ◽  
...  

Abstract In the mechanical vapor recompression (MVR) treatment of landfill leachate, scaling in the evaporator and heat exchanger poses a serious problem. This study explored the reasons for such scaling and proposed acid or ion-exchange pre-treatments to reduce the alkalinity of the landfill leachate nanofiltration concentrate (LLNC) to prevent scaling. The feasibility of these two methods was evaluated and the technical and economic parameters for application were obtained via experiments. A large amount of HCO3- in the LLNC was the main cause of scaling. The acid addition experiment and field application demonstrated that this method could prevent fouling problems. The cost of acid addition was USD 0.18/t. LLNC pre-treatment by ion-exchange showed that a weakly acidic cation-exchange resin performed better than a strongly acidic cation-exchange resin did. The amount of solid residue under an alkalinity of 0 mg/L could be decreased by 92.9% compared with that of raw LLNC during evaporation. Both methods could alleviate scaling and enable the wide application of the MVR evaporation process in landfill leachate treatment.


Author(s):  
Amira A. Helaly

Background: Humic acid is a natural bio-stimulant, which has a major influence on growth and crop quality. Also, Magnetic water treatment enhances both crop productivity and quality, which leads to the efficient use of cultivated land by using water resources available for crop production. This study aims to determine the effects of magnetized water irrigation and application of humic acid with different concentrations as a bio-stimulation on tomato plants, Solanum Lycopersicon cv. Hybrid “86”.Methods: The experiment was conducted during the tow growing seasons of 2018 and 2019 at the Agricultural Experimental Station Farm at Abies region, Faculty of Agriculture, Alexandria University, Egypt. The experiment design was split-plot with three replications. Two irrigation water treatments (magnetized and non-magnetic water) were arranged in the main plots and four concentrations of humic acid (0, 1, 2 and 3 g L-1) were distributed over sub-plots.Result: The results showed that irrigation with magnetized water had a positive effect on the vegetative growth traits, yield and its components and the quality of tomato fruits parameters. There was also a clear desirable effect of humic acid addition with different concentrations, as the results indicated that the use of the highest concentration of humic acid (3 g L-1) reflected the highest values for all the studied traits. The results of the interaction between irrigation with magnetized water and application of humic acid showed that the best results and the highest values for all studied characters were recorded when using magnetic water (MW) combined with 3 g L-1 of humic acid (HA), without significant differences from the interaction treatment MW combined with 2 g L-1 HA for most traits. However, the two treatments combinations MW with 2 g L-1 HA and Non-MW with 3 g L-1 HA didn’t significant differ from each other for all studied characters at the two growing seasons. These results indicated that using the magnetic water with humic acid led to the possibility of reducing the amount of humic acid by one-third and enhances both crop productivity and quality of tomato plants. Generally, we can recommend using magnetized water irrigation with humic acid addition at concentration of 3.g L-1 or 2.g L-1 to enhance the productivity and quality of the tomato plant. 


2021 ◽  
Vol 4 (1) ◽  
pp. 66-81
Author(s):  
Verta Hedyana ◽  
Mochammad Wachid ◽  
Noor Harini

Dragon fruit can be processed into a jam with sugar, pectin, and acid addition. Pectin can be extracted from natural ingredient such as green grass jelly leaf. Stevia leaf powder can be added to a jam as natural sweetener. This study used factorial randomized block design with 3 levels concentration of pectin (0.75%, 1%, 1.25%) and 3 levels concentration of stevia powder (0.5%, 0.75%, 1%). The analyzed parameter such as water content, pH, spreadability, color intensity, total dissolved solid, and organoleptics. Based on the result, there was an interaction between the pectin concentration of green grass jelly leaves and the concentration of stevia leaves on texture and colour of dragon fruit jam.


2021 ◽  
Vol 316 ◽  
pp. 631-636
Author(s):  
L.Ya. Agapova ◽  
S.K. Kilibayeva ◽  
A.N. Zagorodnyaya

The paper presents the results of studies of electrochemical processing of large pieces of metal wastes of rhenium-containing heat-resistant nickel alloys (HRNA) with subsequent processing of the products of electrolysis. It shows the possibility of electrochemical processing of large (up to 2 kg) scrap pieces, without preliminary grinding, in sulfuric acid solution with nitric acid addition, under the current density of 500-1000 A/m2, with a temperature of 30-40о С. Up to 80-90% of rhenium and over 90% of nickel, cobalt, chrome and aluminum can be converted into the solution. Tungsten, tantalum and hafnium remain in the anode slime almost completely. Rhenium, nickel and cobalt remaining in the anode slime can be transferred to the solution, when the slime is chemically processed in sulfuric acid solution with nitric acid addition. The cake remaining after chemical decomposition of anode slimes represents a concentrate of refractory rare metals, containing up to 42% W; 18% Ta; 4% Hf. Rhenium is extracted from the combined solutions from anodic decomposition of HRNA wastes, and chemical dissolution of anode slimes, by the known extraction method in the form of the crude ammonium perrhenate (68,9 mас. % Re). After rhenium extraction the raffinate contains considerable quantities of nickel and cobalt, which can be precipitated by the alkali solution in the form of hydroxides to the nickel-cobalt concentrate, containing 31.5% Ni and 4.8% Co.


Author(s):  
Yingying Li ◽  
Yong Men ◽  
Shuang Liu ◽  
Jinguo Wang ◽  
Kang Wang ◽  
...  

Author(s):  
Hiroyuki Morimoto ◽  
Kei Unoura ◽  
Hideki Nabika
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