Fabrication of 3D scaffolds based on fully biobased unsaturated polyester resins by microstereo-lithography

Additive Manufacturing (AM) technologies are an effective route to fabricate tailor made scaffolds for tissue engineering (TE) and regenerative medicine with microstereo-lithography (µSLA) being one of the most promising techniques to produce high quality 3D structures. Here, we report the crosslinking studies of fully biobased unsaturated polyesters (UPs) with 2-hydroxyethyl methacrylate (HEMA) as the unsaturated monomer (UM), using thermal and µSLA crosslinking processes. The resulting resins were fully characterized in terms of their thermal and mechanical properties. Determination of gel content, water contact angle (WCA), topography and morphology analysis by atomic force microscopy (AFM) and scanning electron microscopy (SEM) were also performed. The results show that the developed unsaturated polyester resins (UPRs) have promising properties for µSLA. In vitro cytotoxicity assays performed with 3T3-L1 cell lines showed that the untreated scaffolds exhibited a maximum cellular viability around 60 %, which was attributed to the acidic nature of the UPRs. The treatment of the UPRs and scaffolds with ethanol (EtOH) improved the cellular viability to 100%. The data presented in this manuscript contribute to improve the performance of biobased unsaturated polyesters in additive manufacturing.

Study on the Perspective of Mechanical Properties and Corrosion Behaviour of Stainless Steel, Plain and TMT Rebars

In the present research, the effects of various alloying elements and microstructural constituents on the mechanical properties and corrosion behaviour have been studied for four different rebars. The microstructures of stainless steel and plain rebar primarily reveal equiaxed ferrite grains and ferrite-pearlite microstructures, respectively, with no evidence of transition zone, whereas tempered martensite at the outer rim, followed by a narrow bainitic transition zone with an internal core of ferrite-pearlite, has been observed for the thermomechanically treated (TMT) rebars. The hardness profiles obtained from this study display maximum hardness at the periphery, which decreases gradually towards the centre, thereby providing the classical U-shaped hardness profile for TMT rebars. The tensile test results confirm that stainless steel rebar exhibits the highest combination of strength (≈755 MPa) and ductility (≈27%). It has been witnessed that in Tafel plots, the corrosion rate increases for all the experimental rebars in 1% HCl solution, which is well expected because the acid solutions generally possess a higher corrosive environment than seawater (3.5% NaCl) due to their acidic nature and lower pH values. However, all the experimental results obtained from Tafel and Nyquist plots correlate well for both 1% HCl and 3.5% NaCl solutions.

Characterization and Properties of Titanium(IV) Oxide, Synthesized by Different Routes

The article considers the influence of precursor type and sol-gel synthesis conditions of TiO2 on its properties. The obtained TiO2 samples were characterized by X-ray diffraction methods, electron microscopy, as a result of which it was found that all the obtained TiO2 powders have the crystallite size in a nanorange of 2.5–17 nm. It was shown that sorption-photocatalytic properties of TiO2 significantly depend on a phase composition, surface acidity, specific surface area and porosity. It was found that the amorphous TiO2 has improved adsorption properties, while crystalline TiO2 is characterized by enhanced photocatalytic properties. Determined acidic nature of the TiO2 surface explains the better sorption and photocatalysis relative to the cationic dye.

Fermentation Dynamics of Ethiopian Traditional Beer (Tella) as Influenced by Substitution of Gesho (Rhamnus prinoides) with Moringa stenopetala: An Innovation for Nutrition

This study was designed to improve Ethiopian traditional beer (tella) with the substitution of gesho by moringa leaves to enhance micronutrients. Substitution of gesho by moringa from 50 to 100% against the biochemical dynamics and nutritional and sensorial profiles of tella was assessed. Incorporation of moringa suppressed the activity of yeast and favored those of lactic acid bacteria, which shifted the properties of the product from a mild alcoholic nature to a low alcoholic and mild acidic nature, revealing the probiotic potential of tella. Moringa leaves at 100% substitution for gesho resulted in the least yeast count compared to the other formulations. The storage of tella samples over periods of 10 days also strengthened the probiotic nature of tella by drastically reducing the yeast cell counts (from 5 logs to <1). This corresponded to the slow increase in the acidity (0.63 to 0.99%), indicating comparatively higher activity of lactic acid bacteria. The best nutritional contents (dietary minerals) and sensorial acceptance of the product were attained at the 50% substitution of gesho by moringa. The implication of the present study is that ethnic foods and beverages can be innovated to meet the nutritional needs of the community.

Utilization of low plants peat brickets for macadamia (Macadamia integrifolia) planting

Currently, the use of organic materials as organic fertilizer has been widely used by farmers. The awareness of farmers to use organic fertilizers has made organic fertilizers increasingly difficult to obtain. Organic fertilizers from chicken, goat and cow farms have generally been ordered and purchased by certain farmers. Therefore, alternative uses of other organic fertilizers need attention. Lowland peat is quite widely available in Indonesia, especially in North Sumatra. Peatlands are spread from the east coast of Aceh Province to the east coast of the Riau Province border. This potential makes it possible for peat to be modified into alternative organic fertilizers. One of the disadvantages of organic fertilizers is the large volume and weight. To overcome this problem, peat is made into briquettes through a pressing process so that its volume can be reduced to 1/3 times its previous volume. In addition, the acidic nature of peat is also expected to be greatly reduced by wasting peat water content. After being made into briquettes, the briquettes are used as organic fertilizer treatment for planting macadamia plants in the field. The results showed that the provision of briquettes from peat could increase the growth of macadamia plants compared to control. However, giving briquettes at a dose of 0.5 kg was not significantly different from giving briquettes up to 1.5 kg.

Changes in Chemical Properties of Banana Pseudostem, Mushroom Media Waste, and Chicken Manure through the Co-Composting Process

Co-composting is an effective approach to biowaste management. The co-composting potential of banana pseudostem (BPS) and mushroom media waste (MMW) with chicken manure (CM) has not been explored, let alone their suitable ratios of co-composting being determined. Meanwhile, the imbalance ratios of the feedstocks used in the process severely restrict the physicochemical properties and quality of the finished product. For this reason, six different ratios of BPS, MMW, and CM, viz. 1:1:1, 1:2:1, 1:3:1, 2:1:1, 2:2:1, and 2:3:1, respectively (T1–T6), were composted together in aerobic conditions to identify the suitable ratio by evaluating the changes in the physicochemical properties in the composting process. According to the ratio of treatments, the feedstocks were mixed on fresh weight basis. The turning process of co-composting piles was repeated at seven-day intervals to maintain the uniform aeration throughout the composting period. The piles having BPS, MMW, and CM at ratios of 1:2:1, 1:3:1, and 2:3:1, respectively, demonstrated a longer thermophilic phase, indicating more complete decomposition and earlier maturity compared to piles with higher amount of BPS. Of the ratios, BPS:MMW:CM at 1:2:1 ratio (T2) resulted in the highest total nitrogen (1.53%), lowest C:N ratio (12.4), organic matter loss (54.5%), and increased CEC (41.3 cmol/kg). The highest germination index (129%) was also recorded in the T2 compost, indicating that it was toxic-free and safe for seed germination. The nutrient-rich compost with high alkaline pH (≥10) can effectively ameliorate soils of an acidic nature, for example, the acidity of Ultisols and Oxisols.

Synthesis of 1,8-dioxo-octahydro-xanthene and tetrahydrobenzo[b]pyran derivatives promoted by two bis-imidazolium-based ionic liquids

Aim and objective: In this work, we have prepared two bis-dicationic ionic liquids with the same cationic core (Bis-imidazole) and different counter-anions using sulfuric acid and perchloric acids. After that, the efficiency and ability of these compounds as catalysts were investigated and compared in the promotion of Knoevenagel condensation and synthesis of benzo[b]pyran derivatives to see the effect of the anionic counter-part in the reaction. Material and method: In a 25 mL round-bottomed flask, a mixture of aldehyde (1.0 mmol), 1,3-cyclodicarbonyl (2.0 mmol) and the desired amount of the mentioned acidic ionic liquids was heated at 90°C in the absence of solvent (Reaction A) or In a 25 mL round-bottomed flask, a mixture of aldehyde (1.0 mmol), 1,3-cyclodicarbonyl (1.0 mmol), malononitrile, (1.1 mmol) and optimized amounts of the ionic liquid in water (3.0 mL) was heated at 80°C (Reaction B) for the appropriated time. After the completion of the reactions which were monitored by TLC (n-hexane: EtOAc; 3:1), 10 mL of water was added and the mixture was stirred for 2 minutes. Then, the products were separated by filtration and were washed several times with water. After drying, the pure products were obtained while there was no need to further. Results: Comparison of the obtained results from both of the ionic liquids revealed that [H2-Bisim][HSO4]2 because of its more acidic structure had a more catalytic activity for the preparation of 1,8-dioxo-octahydro-xanthene derivatives but [H2-Bisim][ClO4]2 was relatively more efficient for the synthesis of tetrahydrobenzo[b]pyran derivatives since the stronger acidic nature of [H2-Bisim][HSO4]2 may prevent the simple activation of malononitrile in the reaction media. Conclusion: In this study, we have introduced efficient methods for the synthesis of 1,8-dioxo-octahydro-xanthene and tetrahydrobenzo[b]pyran derivatives in the presence of catalytic amounts of [H2-Bisim][ClO4]2 and [H2-Bisim][HSO4]2 These methods have several advantages such as ease of preparation and handling of the catalysts, high reaction rates, excellent yields, eco-friendly procedures and simple work-up.

Using Proanthocyanidin as a Root Dentin Conditioner for GIC Restorations

Glass ionomer cements (GICs) are considered the material of choice for restoration of root carious lesions (RCLs). When bonding to demineralized dentin, the collapse of dentinal collagen during restorative treatment may pose challenges. Considering its acidic nature and collagen biomodification effects, proanthocyanidin (PAC) could be potentially used as a dentin conditioner to remove the smear layer while simultaneously acting to biomodify the dentinal collagen involved in the bonding interface. In this study, 6.5% w/v PAC was used as a conditioner for sound (SD) and laboratory demineralized (DD) root dentin before bonding to resin-modified GIC (FII), casein phosphopeptide–amorphous calcium phosphate (CPP-ACP)–modified GIC (FVII), or a high-viscosity GIC (FIX). Root dentin conditioned with deionized distilled water (DDW) or polyacrylic acid (PAA) served as controls. Results indicated FII showed higher shear bond strength (SBS) on SD than the other 2 GICs, especially in PAA-conditioned samples; FIX showed significantly higher SBS than FII and FVII on PAA- or PAC-conditioned DD. In each category of GIC, PAA and PAC did not have a significant influence on SBS in most cases compared to DDW except for a significant decrease in PAC-conditioned SD bonded to FII and a significant increase in PAA-conditioned DD bonded to FIX. The bonding interface between GIC and SD was generally more resistant to the acid-base challenge than DD. Although the alterations in failure modes indicated a compromised interfacial interaction between GICs and PAC-treated root dentin, biomodification effects of PAC on dentin were observed from Raman microspectroscopy analysis in terms of the changes in mineral-to-matrix ratio and hydroxyproline-to-proline ratio of dentin adjacent to the bonding interface, especially of DD. Results from this study also indicated the possibility of using in situ characterization such as Raman microspectroscopy as a complementary approach to SBS test to investigate the integrity of the bonding interface.

Non-Destructive Analytical Investigation of Decorative Wallpapers Samples of the Nineteenth Century before Their Restoration

In this work, decorative wallpapers (19th century) from an historical palace located in Oiartzun (Basque Country, Spain) were analyzed before their restoration. Micro-energy dispersive X-ray fluorescence spectroscopy, Raman spectroscopy, and attenuated total reflectance infrared spectroscopy were used to investigate the elemental and molecular composition of pigments, the presence of binders, and the state of conservation of the paper support. The aim of the investigation was trying to understand the possible degradation pathways and identify the raw materials in order to choose the best restoration protocol according to the original aspect of wallpapers. As stated from both the elemental distribution and the identification of mineral phases by Raman spectroscopy, the most used pigment was lead chromate. It was mixed with other pigments such as ultramarine blue, zinc chromate, hematite, and atacamite among others to obtain different shades and they were applied mixed with an animal glue. Brass, identified thanks to elemental micro-EDXRF maps, was employed as a shiny decorative element. In addition, a partial degradation of cellulose was detected due to its natural ageing, the acidic nature of lignin, and to a phenomenon of humidity of the walls. Probably the deposition of black particulate matter was the cause of the darkening of the painting surfaces.

Fermentation Dynamics of Ethiopian Traditional Beer (Tella) As Influenced by Substitution of Gesho (Rhamnus prinoides) With Moringa Stenopetala as Innovation for Nutrition

This study was designed to improve Ethiopian traditional beer &ndash; tella with the substitution of gesho by moringa leaves to enhance micronutrients. Substation of gesho by moringa from 50 &ndash; 100% against the biochemical dynamics, nutritional and sensorial profiles of tella was assessed. Incorporation of moringa suppressed the activities of yeast and favored that of lactic acid bacteria, which shifted the property of the product from mild alcoholic nature to low alcoholic and mild acidic nature, revealing the probiotic potential of tella. Moringa leaves at 100% substitution for gesho resulted in to the least yeast count compared to the other formulations. The storage of tella samples over periods of 10 days also strengthened the probiotic nature of tella by drastically reducing the yeast cell counts (from 5 logs to &amp;lt;1). This corresponded to the slow increase in the acidity (0.63 to 0.99%), indicating comparatively higher activities of lactic acid bacteria. The best nutritional contents (dietary minerals) and sensorial acceptance of the product was attained at the 50% substitution of gesho by moringa. The implication of the present study is that ethnic foods and beverages can be innovated to meet the nutritional needs of the community