Chemical Treatment of Black Tiger nut Tubers (Cyperusesculentus) Variety to Obtain a Bio-based Product

The purpose of this study is to improve microbiological qualities of black tiger nut tubers. Thereby, black variety of tiger nut tubers (Cyperus esculentus) were differently processed in ascorbic acid and alkaline (Ca(OH)2 and Kanwa (alkaline calcium carbonate locally used to soften vegetable)) solutions at different concentrations and temperatures. The effect of these treatments on the water content (swelling), soluble loss, dehulling efficiency and microbial load was investigated. Water content or swelling of the tiger nut soaked in acid and alkaline solutions can be predicted by Peleg model like with brown variety.of C. esculentus tubers. This swelling lead to enhance dehulling efficiency of tuber but caused soluble solute loss overall at the highest temperature of soaking in vitamin C solution. Like soaking in water, the constant of Peleg (k1) decrease with the increase of the temperature of soaking, whereas the constant of capacity of Peleg (k2) is approximately 0.018% for all the conditions. Dehulling efficiency also increased with increasing temperatures (65% at 20°C to 70% at 60°C) for tiger nut tubers soaked in water (0 g/L), dehulling efficiency appeared most strongly affected by concentrations and temperatures of soaking solutions. Like dehulling efficiency, ascorbic solutions has given the best results in term of reduction of microbial load compared to the other soaking solutions. This reduction is considerable at the higher temperatures, reaching a maximum of 4.8 log reduction. Soaking and dehulling treatments gave to black tiger nut tuber effective decontamination in term of microbial load and obtained good microbiological quality for final process.

Engineering of a Biomimetic Interface between a Native Dental Tissue and Restorative Composite and Its Study Using Synchrotron FTIR Microscopic Mapping

The aim of this work is to develop a biomimetic interface between the natural tooth tissue and the restorative composite and to study it on the basis of synchrotron micro-FTIR mapping and multidimensional processing of the spectral data array. Using hierarchical cluster analysis of 3D FTIR data revealed marked improvements in the formation of the dentine/adhesive/dental hybrid interface using a biomimetic approach. The use of a biomimetic strategy (application of an amino acid–modified primer, alkaline calcium and a nano-c-HAp–modified adhesive) allowed the formation of a matrix that can be structurally integrated with natural dentine and dental composite. The biomimetic hybrid layer was characterised by homogeneous chemical composition and a higher degree of conversion of the adhesive during polymerisation, which should provide optimal integration of the dental composite with the dentine.

Review of Recent Research on Grease

Based on the analysis of scientific, technical, and patent literature, the main directions of the development of greases are described: super-alkaline calcium greases for highly loaded friction units, research into the possibilities of nanosized particles as additives to multifunctional greases, and the production of low-temperature greases on biodegradable polyester bases.

Viscosity profile of Eucheuma spinosum carrageenan from Nusa Penida (Bali), Sumenep (Madura), and Takalar (Sulawesi Selatan)

The research was conducted to determine the viscosity profile of carrageenan solution obtained from three different coastal region of Nusa Penida, Sumenep, and Takalar as a result of a decrease in temperature with presence cations K+ and Ca2+. Carrageenan was extracted from Eucheuma spinosum using hot alkaline calcium hydroxide Ca(OH)2 at 95°C, pH was decreased with HCl, carrageenan was precipitated with ethanol, dried and grinded. The viscosity profile of carrageenan was determined by addition of K+ (0.005-0.03% KCl) and Ca2+ (0.005-0.02% CaCl2)using a Rapid Visco Analyser (RVA). The viscosity profile of carrageenan solution changed upon cooling started from a dilute at the initial temperature of 80°C, and then increased as temperature decreased to 20°C. The viscosity of carrageenan E. spinosum from Nusa Penida, Sumenep, and Takalar without the addition of K+ and Ca2+ at a temperature of 80°C respectively were 90, 120, and 130 mPa.s. The viscosity of carrageenan from Nusa Penida, Sumenep, and Takalar in the presence of K+ and Ca2+ increased with increasing time and decreasing temperature. The viscosity of carrageenan from Nusa Penida in the presence of K+ (0.005-0.03% KCl) at 55oC becomes 125, 250, 300 mPa.s, Sumenep 280, 290, and 360 mPa.s, and Takalar 420, 420, and 420 mPa.s. While, in the presence of Ca2+ (0.01-0.02% % CaCl2) at 55oC, the viscosity of carrageenan from Nusa Penida, Sumenep, and Takalar have been formed gelling. Increasing of viscosity of carrageenan from Nusa Penida, Sumenep, and Takalar in the presence of kation Ca2+ was required a faster time and higher temperatures than K+. Carrageenan solution from E. spinosum originated from different coastal regions showed different viscosity profiles.<br />Keywords: Eucheuma spinosum, carrageenan, cation, temperature, viscosity profile

Study on Properties of High Performance Marine Concrete under Seawater Attack

Through artificial seawater simulation test this paper analyzed erosion mechanism of concrete corroded by the ions in seawater. High performance marine concrete was successful developed because of mineral admixture and corrosion-resistance additive double adding. The paper researched the durability of concrete containing freeze-thaw cycles and chloride ions diffusion. Modern testing technologies were used such as scanning electron microscopy and differential thermal analysis in the experiment. Research founded that the amount of unstable or metastable matter reduced such as calcium hydroxide and high alkaline calcium aluminates in the marine concrete. There were more compact hydration products created which made the structure stabler and denser. Those were the reasons that the marine concrete had excellent performances in terms of erosion-resistance and durability.

Elastic and structural properties of alkaline-calcium silica hydrogels

Brillouin scattering has been used to study the elastic properties of alkaline-calcium silica hydrogels synthesized from the precipitation of sodium silicate solution with calcium hydroxide. To the best of our knowledge, this is the first determination of the bulk elastic moduli for this type of alkaline-calcium silica hydrogel, also referred to as the alkali-silica reaction (ASR) gel. The measured bulk moduli for the alkaline-calcium silica hydrogels were found to be between 4 and 8 GPa for the gel containing 0.08 M Ca(OH)2 and between 10 and 25 GPa for the gel containing 0.8 M Ca(OH)2, increasing with increasing pressure. Fourier transform infrared measurements were made to correlate the moduli to the silica speciation and network formation within the gels as a function of Ca(OH)2 content. Significantly, for the concentrations considered, both the interconnection of the silica species and the bulk modulus increased with increasing Ca(OH)2 content. On this basis, Brillouin scattering was confirmed to be a useful method for distinguishing between the bulk moduli of alkaline-calcium silica hydrogels in terms of chemical composition. The potential for further characterization of ASR gels as a function of composition and water content by this technique is highly promising.