Mineralization treatment of European oak heartwood with calcium oxalate for improved fire retardancy

Within the focus to apply substances for wood protections, here fire retardants, with low hazardous and low environmental impact is of interest. Additionally, European oak is an attractive species for various interior and exterior applications. However, oak is classified as very heavily treatable and thus impregnation is challenging. However, the focus of this study was to treat European oak with a new fire retardant based on an in-situ calcium oxalate deposition. Thin oak specimens with a thickness of 4 mm were investigated with two various formulations of aqueous salt solutions (potassium oxalate and calcium chloride, and potassium oxalate and calcium acetate) to obtain an in-situ mineralization of calcium oxalate during a two-step impregnation process. The uptake, the distribution, and the penetration of the salts for both applied formulations were investigated. Additionally, fire retardant properties were investigated in a single flame source test. It could be demonstrated that an acceptable degree of treatability was achieved for both applied formulations. The fire retardancy of the so mineralized material was clearly improved. Synergetic effects which might be caused by the reaction side products of the various formulations were found to be neglectable.

Highly Porous Carbons Synthesized from Tannic Acid via a Combined Mechanochemical Salt-Templating and Mild Activation Strategy

Highly porous activated carbons were synthesized via the mechanochemical salt-templating method using both sustainable precursors and sustainable chemical activators. Tannic acid is a polyphenolic compound derived from biomass, which, together with urea, can serve as a low-cost, environmentally friendly precursor for the preparation of efficient N-doped carbons. The use of various organic and inorganic salts as activating agents afforded carbons with diverse structural and physicochemical characteristics, e.g., their specific surface areas ranged from 1190 m2·g−1 to 3060 m2·g−1. Coupling the salt-templating method and chemical activation with potassium oxalate appeared to be an efficient strategy for the synthesis of a highly porous carbon with a specific surface area of 3060 m2·g−1, a large total pore volume of 3.07 cm3·g−1 and high H2 and CO2 adsorption capacities of 13.2 mmol·g−1 at −196 °C and 4.7 mmol·g−1 at 0 °C, respectively. The most microporous carbon from the series exhibited a CO2 uptake capacity as high as 6.4 mmol·g−1 at 1 bar and 0 °C. Moreover, these samples showed exceptionally high thermal stability. Such activated carbons obtained from readily available sustainable precursors and activators are attractive for several applications in adsorption and catalysis.

Comparison between different sources of minerals in horses with nutritional secondary hyperparathyroidism

ABSTRACT Minerals perform several functions in the body, such as coagulation actions, muscle contraction, enzymatic and hormonal production, among others. This study aims to evaluate the effect of a 150 days chelated and not chelated mineral supplementation with and without potassium oxalate on serological parameters and bone mineral density of horses. Twenty-four crossbred yearlings (12 females and 12 males) with an average age of 21±3 months and body weight of 330.8±37.9kg were divided into four groups containing six equines in each (three females and three males) in a completely randomized design with repeated measurements in a 2x2 factorial arrangement. Treatments were: 1 - chelated minerals compound; 2 - chelated minerals compound and potassium oxalate; 3 - not chelated minerals compound; and 4 - not chelated minerals compound and potassium oxalate. Clinical signs of nutritional secondary hyperparathyroidism (NSH) were observed only in treatment 4. Results showed no treatment effect in bone biopsy for calcium, phosphorus and bone density. There were significant reductions of parathyroid hormone (PTH) means concentrations in treatments 2 and 4 during supplementation. Animals supplemented with chelated minerals compounds avoided mineral imbalances and NSH even when in dietary potassium oxalate challenged.

Comparative and Stability Study of Glucose Concentrations Measured in both Sodium Fluoride and Serum Separator tubes

IntroductionSodium fluoride/potassium oxalate (NaF/KOx) tubes were once regarded as the gold-standard tubes for glucose analysis. Even though their ineffectiveness in immediately inhibiting glycolysis has been reported in several studies especially in the first 1–4hours, they are still used in our clinical Biochemistry laboratory for glucose measurement. However in its absence, only SSTs are employed for glucose measurement.AimTo determine whether SSTs can replace NaF/KOx tubes for laboratory-based measurement of blood glucose and to assess the stability of glucose concentrations for 3 days periodMethodsDuring the study period (1 March to 11 April, 2015), a total of 50 paired samples collected separately in NaF/KOx tubes and SSTs from healthy adult participants in the Gambia Adults Reference Intervals Study (GARIS) project were used as the project sample size. The samples were analysed within 2hours, and at 24hours, 42hours and 72hours time-points following blood collection and separation using Vitros 350 dry chemistry analyser. The GARIS samples were treated as clinical samples.ResultsThere was no significant difference in the mean glucose concentrations between the two tubes (Mean difference= 0.06mmol/L; P=0.38) recorded in the different time-points. Using growth trajectory and mixed effects model, the study data showed no significant change in the glucose concentrations (p=0.25) for three days period.ConclusionsThe study confirms that SSTs can produce similar glucose results when employed in the absence of NaF/KOx tubes. Besides, the glucose concentrations were stable in both tubes for three days when the samples were separated within two hours and refrigerated in 2-8°C.

Assessment of the acid resistance behaviour of dentin tubules occluded by different desensitizers

Aim: To evaluate the efficacy of in-office and home-based products in the prevention of dentinal hypersensitivity on dentin discs. Methodology: Ninety-six dentin disc samples of 1 mm were divided equally into six groups as follows: TeethmateTM, Smartprotect®, novamin®, Arginine calcium carbonate, potassium oxalate with rinse and saline (control). After acid etching, test agents were applied, and eight samples in each group were subjected to citric acid. SEM examination (3000x) and statistical analysis were carried out. Results: Before citric acid challenge, novamin® and teethmate had superiority when compared to others (p<0.001), but there was no a statistical difference between novamin® and teethmate. After citric acid challenge, teethmate and smartprotect showed resistance on occluded tubules. The decreasing in the level of occluded tubules in novamin® group was statistically significant (p<0.05). In-office products including teethmate and smartprotect were found more successful compared to home-based products. Smartprotect resisted against to citric acid (0.506). Conclusion: Novamin® showed a successful occlusion in all tubules before acid challenge whereas; it was the most unsuccessful group after acid challenge when compared to other agents. In-office agents were found to be more successful in reducing dentine permeability than home-care products. In-office agents showed more resistance to acid attacks. Further studies are needed to assess the efficacy of desensitizer agents. How to cite this article: Karayürek F, Arpağ OF. Assessment of the acid resistance behaviour of dentin tubules occluded by different desensitizers. Int Dent Res 2020;10(3):80-9. https://doi.org/10.5577/intdentres.2020.vol10.no3.3 Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

Pressureless and Low-Pressure Synthesis of Microporous Carbon Spheres Applied to CO2 Adsorption

In this work, low-pressure synthesis of carbon spheres from resorcinol and formaldehyde using an autoclave is presented. The influence of reaction time and process temperature as well as the effect of potassium oxalate, an activator, on the morphology and CO2 adsorption properties was studied. The properties of materials produced at pressureless (atmospheric) conditions were compared with those synthesized under higher pressures. The results of this work show that enhanced pressure treatment is not necessary to produce high-quality carbon spheres, and the morphology and porosity of the spheres produced without an activation step at pressureless conditions are not significantly different from those obtained at higher pressures. In addition, CO2 uptake was not affected by elevated pressure synthesis. It was also demonstrated that addition of the activator (potassium oxalate) had much more effect on key properties than the applied pressure treatment. The use of potassium oxalate as an activator caused non-uniform size distribution of spherical particles. Simultaneously higher values of surface area and total pore volumes were reached. A pressure treatment of the carbon materials in the autoclave significantly enhanced the CO2 uptake at 25 °C, but had no effect on it at 0 °C.

Potassium Oxalate as an Alternative Activating Reagent of Corn Starch-Derived Porous Carbons for Methane Storage

Fossil fuels are a main source of energy but also the major contributor to global warming. Therefore, the needs for alternative renewable and sustainable energy sources such as natural gas is increasing; nevertheless, for practical use, efficient gas storage materials of alternative fuels are essential. Activated carbons (ACs) are a promising candidate as gas storage materials due to their narrow micropore size distribution and high porosity. Appropriate selection of the activating reagents is key factor for the preparation of high-performance ACs. Recently, potassium hydroxide is the most widely used activating reagent, but its application for plant-scale production is reluctant by its toxicity and high corrosiveness. Hence, in this study, the less corrosive and easy manageable potassium oxalate salt was used as an alternative reagent to prepare ACs from corn starch, for methane storage. The products were characterized based on their N2 adsorption–desorption isotherms at 77 K and on their specific surface area and pore size distributions, respectively calculated via the Brunauer–Emmett–Teller (BET) equation and the non-local density functional (NLDFT) theory. The methane storage capacities and adsorption cycles were investigated with a high-pressure adsorption instrument operating at 298 K and 35 bar.