This research presents a new study in reactive distillation by adopting a consecutive reaction . The adopted consecutive reaction was the saponification reaction of diethyl adipate with NaOH solution. The saponification reaction occurs in two steps. The distillation process had the role of withdrawing the intermediate product i.e. monoethyl adipate from the reacting mixture before the second conversion to disodium adipate occurred. It was found that monoethyl adipate appeared successfully in the distillate liquid. The percentage conversion from di-ester to monoester was greatly enhanced (reaching 86%) relative to only 15.3% for the case of reaction without distillation .This means 5 times enhancement . The presence of two layers in both the

This research presents a new study in reactive distillation by adopting a consecutive reaction . The adopted consecutive reaction was the saponification reaction of diethyl adipate with NaOH solution. The saponification reaction occurs in two steps. The distillation process had the role of withdrawing the intermediate product i.e. monoethyl adipate from the reacting mixture before the second conversion to disodium adipate occurred. It was found that monoethyl adipate appeared successfully in the distillate liquid. The percentage conversion from di-ester to monoester was greatly enhanced (reaching 86%) relative to only 15.3% for the case of reaction without distillation .This means 5 times enhancement . The presence of two layers in both

Every year, millions of tons of waste glass are created across the globe. It is disposed of in landfills, which is unsustainable since it does not disintegrate into the environment. This study aims to produce reactive powder concrete by using recycled glass powder and determine the influence on the mechanical properties. This study investigated the effect of partial replacement of cement with recycled glass powder at two percentages (0, 20) % by weight of cement on some mechanical properties (Fresh density, Splitting tensile strength, Impact Strength, and voids%) of reactive powder concrete containing 1 % micro steel (MSRPC). Furthermore, using steam curing for (5 hours) at 90 degrees celsius after hardening the sample directly, RPC was

ABSTRACT Background: This study measured the effects of three parameters pH value, length of immersion and type of archwire on metal ions released from orthodontic appliances. Materials and Methods: Ninety maxillary halves simulated fixed orthodontic appliances that were immersed in artificial saliva of different pH values (6.75, 5 and 3.5) during 28 day period. Three types of archwires were used: stainless steel, nickel titanium and thermal activated nickel titanium. The quantity of nickel and chromium ions was determined with the use of atomic force spectrophotometer while iron ions by spectrophotometer. Each orthodontic set was weighted two times, before the ligation and immersion in the artificial saliva and after 28 days at the end of

Al-Si alloys which are widely used in engineering applications due to their outstanding properties can be modified for more enhancements in their properties. Current work investigated the ability of these alloys to be modified by casting them through the addition of nanoparticles. So, Multi-wall carbon nanotubes (CNT) and titanium carbide ceramic particles (TIC) with size of (20 nm) were added with different amounts started from (0.5 up to 3%) weight  to cast alloy A356 that was considered to be the base metal matrix, then stirred with different speeds of (270, 800, 1500, 2150) rpm at 520 °C for one minute. The results showed change in microstructure’ shape of the casted alloys from the dendritic to spherical gra

Ab – initio restricted Hartree - Fock method within the framework of large unit cell (LUC) formalism is used to investigate the electronic structure of Si and Ge nanocrystals. The surface and core properties are investigated. A large unit cell of 8 atoms is used in the present analysis. Cohesive energy, energy gap, conduction and valence band widths are obtained from the electronic structure calculations. The results are compared with available experimental data and theoretical results of other investigators. The calculated lattice constant is found to be slightly larger than the corresponding experimental value because we use only 8 atoms and we compared the results with that of the bulk crystals, nanoclusters are expected to have str

To achieve sustainability in the field of civil engineering, there has become a great interest in developing reactive powder concrete RPC through the use of environmentally friendly materials to reduce the release of CO₂ gas produced from cement factories as well as contribute to the recycling of industrial wastes that have a great impact on environmental pollution.

In this study, reactive powder concrete was prepared using total binder content of 800 kg/m³, water to binder ratio (0.275), and micro steel fibers  1% by volume of concrete. The experimental program included replacing fly ash with (8, 12, 16) % by cement weight to find the optimal ratio, which achieved the best mechanical proper