The effects of Li sub(2)O-ZnO-B sub(2)O sub(3) (LZB) glass additive on the sintering behavior, phase composition, microstructure and microwave dielectric properties of Li sub(2)Zn sub(3)Ti sub(4)O ...sub(12) ceramics were investigated. The addition of a small amount of LZB glass can reduce the sintering temperature of Li sub(2)Zn sub(3)Ti sub(4)O sub(12) ceramics from 1,075 to 900 degree C without much degradation of the microwave dielectric properties. Only a single-phase Li sub(2)Zn sub(3)Ti sub(4)O sub(12) is formed in Li sub(2)Zn sub(3)Ti sub(4)O sub(12) ceramic with LZB addition. Typically, the 1.5 wt% LZB glass-added Li sub(2)Zn sub(3)Ti sub(4)O sub(12) ceramic sintered at 900 degree C for 2 h can reach a high relative density of 97.5 % and exhibits good microwave dielectric properties, i.e., relative dielectric constant ( epsilon sub( )r = 19.1, quality factor (Q) = 7083.5 at 9 GHz, and temperature coefficient of resonant frequency ( tau sub( )f = - 48.9 ppm/ degree C. In addition, the ceramic could be co-fired well with an Ag electrode, which is made it as a promising dielectric ceramic for low temperature co-fired ceramics technology application.
This report represents the conclusions of a Joint FAO/WHO Expert Committee convened to evaluate the safety of various food additives, with a view to recommending acceptable daily intakes (ADIs) and ...to preparing specifications for identity and purity. The first part of the report contains a general discussion of the principles governing the toxicological evaluation and assessment of intake of food additives. A summary follows of the Committee's evaluations of technical, toxicological and intake data for certain food additives: branching glycosyltransferase from Rhodothermus obamensis expressed in Bacillus subtilis, cassia gum, cyclamic acid and its salts (dietary exposure assessment), cyclotetraglucose and cyclotetraglucose syrup, ferrous ammonium phosphate, glycerol ester of gum rosin, glycerol ester of tall oil rosin, lycopene from all sources, lycopene extract from tomato, mineral oil (low and medium viscosity) class II and class III, octenyl succinic acid modified gum arabic, sodium hydrogen sulfate and sucrose oligoesters type I and type II. Specifications for the following food additives were revised: diacetyltartaric acid and fatty acid esters of glycerol, ethyl lauroyl arginate, glycerol ester of wood rosin, nisin preparation, nitrous oxide, pectins, starch sodium octenyl succinate, tannic acid, titanium dioxide and triethyl citrate. Annexed to the report are tables summarizing the Committee's recommendations for intakes and toxicological evaluations of the food additives considered.
Sweet has always been a very important basic taste for mankind, although sweetness is always related to either weight gain or teeth decay. Sweeteners entered the food industry back in the 1800's and ...are now staple in foodstuffs. Despite their long relationship with food, sweeteners have been in the spotlights for many reasons. Since being the perfect choice for diabetics, to the dangers concerning toxicity, cancer and other health issues associated with their consumption, sweeteners have come a long way. The conflicting results for the same sweeteners and the divergent regulations are fuel for a wide debate on the impact of sweeteners in the industry, health and lifestyle of mankind. In this review, the history, main concerns, benefits, disadvantages, classification and future trends are revisited for nutritive, intense and natural food additives, while future perspectives are hypothesized.
•Sweeteners are essential to reduce caloric intake in diets.•Some sweeteners are still seen with distrust by consumers.•Natural sweeteners are gaining interest from consumers and companies.•There are still some legislation discrepancies among the EFSA and FDA concerning sweeteners.
In order to prepare dense B sub(4)C-SiC composites under relatively low temperature without any additive, stacking disordered B sub(4)C-SiC ultrafine composite powders were fabricated by mechanical ...alloying firstly. Subsequently, hot pressing sintering was applied to produce a dense B sub(4)C-SiC composite under relatively low temperature (1800-1950 degree C) without any additive. For the samples sintered at 1950 degree C for 30 min, the obtained relative density, Vickers hardness, flexural strength and fracture toughness were 96%, 24 GPa, 430 MPa, and 4.6 MPa.m super( one half ), respectively. The microstructural characterization showed that the main fracture mode was transgranular. The transgranular facture is caused by the powerful interfacial bonding between B sub(4)C and SiC. The density of the samples sintered with composite powders was 13% higher than the density of the samples sintered with mixed powders under the same conditions, indicating that the composite powders had an improved sintering activity due to their disordered structure. Meanwhile, the role of disorder-order transformation-driven sintering of ceramics was demonstrated.
Amine reclaimer wastes (ARW) generated in CO sub(2) capture processes demand suitable disposal means. Such wastes contain remaining amine, NH sub(3) and other degradation compounds. This study ...investigated the potential of using ARW as a NO sub(x) reducing agent, under laboratory conditions in a flow reactor. A simulated flue gas containing about 500 ppm of NO and 5% O sub(2) was injected with liquid ARW under different stoichiometric ratios (TN/NO - total N to nitric oxide ratio) and temperatures. The ARW was obtained from a distillation monoethanolamine reclaimer in an industrial CO sub(2) capture facility with a coal fired boiler. The results indicate that ARW has a significant NO sub(x) reduction potential when injected with TN/NO ratios in excess of 1. The optimum temperature is close to 950 degree C, where 40% reduction in NO sub(x) is recorded with a TN/NO ratio of 1.6. Increasing TN/NO to 8.5 resulted in a 96% reduction. At low TN/NO ratios (<1.6), the NO sub(x) reduction potential of ARW is comparable to that of monoethanolamine, but lower than that of NH sub(3). Nevertheless, the fact that ARW is a waste product, together with its demonstrated NO sub(x) reduction capability and its calorific value contribution, makes it attractive as an additive to combustion processes, including cement industry kilns.
In the Additive Manufacturing (AM) community, the binder jet printing (BJP) process is known to produce parts not suitable for most structural applications due to the insufficient consolidation of ...the powder in the finished part. A new processing protocol for the BJP is presented to reach near full density and better surface finish for stainless steel (SS) parts. Two main modifications from the standard BJP processing are (1) the use of the mixtures of various powders and (2) the adaptation of a full sintering cycle in a vacuum furnace. Two distinct average particle sizes of SS powder were used to improve the packing density in the printing stage. Improving the packing density of the printed powder helps to consolidate the powder better and to reduce the shape distortion in the final parts. More importantly, an extremely small amount of the sintering additive was added to enhance the densification, which reduces the sintering time and temperature. In particular, up to 0.5wt% of boron compounds as sintering additives were used to achieve a near full density in the final part. Thus, the starting powder, consisting of two distinct SS powders and sintering additive, is mixed before building a part in a layer-by-layer fashion. After completing the printing process with a binder phase, the printed powders are cured and the binder phase is burned out at 460°C before sintering at 1250°C for 6h in a vacuum furnace to reach near-full densities (up to 99.6%). A subtle difference between SS 420 and SS 316 was evident because the enhanced oxidation during the binder burnout cycle on SS 316 due to a higher surface area of the SS 316 powder used in the experiment. The main contribution of this work is to provide the BJP process an important ability to fully consolidate the powders under an isothermal condition, which enable us to produce the final parts without residual stresses.
•The main drawback of binder jet printing (BJP) process is known to produce parts not suitable for most structural applications.•In this paper, this main drawback of BJP is addressed by making few simple modifications to the BJP processing protocol for stainless steel 420.•These modifications include the designed starting powder that includes bimodal SS 420 powders and an extremely small amount (up to 0.5%) of sintering additive (BN), the binder burnout cycle and the full sintering cycle with a vacuum furnace.•These modifications have enabled us to produce highly dense (up to 99.6% relative density) SS 420 parts with better surface finish and the hardness comparable to commercially available SS 420 plate.•The main contribution of this work is to provide the BJP process an important ability to fully consolidate the powders under an isothermal condition, which enable us to produce the final parts without residual stresses.
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•Palm biodiesel production parameters optimized utilizing the Response Surface Methodology.•The maximum BTE recorded for B30 + Al2O3 compared to other tested blends at all the test ...conditions.•The minimum CO level observed for B30 + TiO2 as compared to other biodiesel blends at 2300 rpm.•B30 + CNT indicated a significant reduction in NOx intensity as compared to other blends.•Palm biodiesel blended with nanoparticle additives improved engine performance.
The present study aims to evaluate the emission and performance characteristics of a CI engine using biodiesel blends with three different nanoparticles. Biodiesel was prepared from palm oil using transesterification process. Biodiesel yield has been optimized using response surface methodology, which develops an interaction among the independent operating parameters reaction temperature methanol to oil ratio, and catalyst concentration, where they are changed as follows: 50–65 °C, 5:1–12:1, and 0.25–1.75, respectively. Nano fuel blends were prepared by dispersing CNT, TiO2 and Al2O3 nanoparticles into the B30 blend. The stability of these nanoparticles was improved by adding sodium dodecyl sulfate (SDS) as a surfactant, and the stability was characterized by ultraviolet–visible spectrometry. These nanoparticles were mingled with palm methyl ester at a proportion of 100 ppm using an ultrasonication water bath. The engine performance and emission characteristics were determined at varying engine speed and a full load condition. At all engine speeds, B30 with Al2O3 ternary fuel blend exhibits a promising reduction in brake specific fuel consumption (BSFC) of 5.98%. A significant improvement of 9.83%, 3.91% and 1.37% in brake thermal efficiency (BTE) has been observed for Al2O3, CNT, and TiO2 additives as compared to B10 blend, respectively. B30 with TiO2 ternary blend shows a sharp reduction of 27.89% and 30.68% in the CO and HC emissions respectively, and 10.37% decrease in NOx level with the addition of CNT as a fuel additive in the ternary fuel blend. Palm biodiesel blended with nanoparticle additives enhanced both engine performance and emission characteristics.
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