We performed a systematic investigation of CO2 electroreduction to CH4 and CH3OH on copper-based alloys stepped surfaces using density functional theory calculations associated with the standard hydrogen electrode model. We determined the correlations between CO adsorption energy and the other key C x H y O z intermediates adsorption energy, the overpotential, the limiting-potential elementary step, and selectivity to CH4, CH3OH, HCOOH, and H2. The electrode efficiency decrease by OH* poisoning and the H2 evolution is also investigated. The results demonstrate that the CO* protonation is the limiting-potential step on most surfaces, with the exception on Cu3Au and Cu3Co surfaces. In spite of the excessive strong CO* interaction on some surfaces, the overpotentials reduce when the degree of CO* adsorption energy and HCO*/COH* adsorption energy decoupling increases. The CO* adsorption energy is a good descriptor for linear scaling correlations with the other C x H y O z intermediates due to the similar charge transfer characteristics of the C–O bond in CO* and those intermediates. The formic acid production can be efficiently catalyzed on Cu3Pt, Cu3Ni, Cu3Co, and Cu3Rh surfaces. Methanol production is favorable on Cu3Pd and Cu3Pt surfaces, yet they show high overpotential (∼0.7 V). The key of methanol selectivity is CH2OH* intermediate formation favorability associated with the preference of CH2OH* protonation at the C atom over the O atom. The calculations reveal that the electroreduction activity on Cu-based alloys catalysts do not show a volcano-type relation as was previously found on pure metal catalysts.

In this paper, we report on the enhanced strength of glass ionomer cement (GIC) by using the process of pre acid-base reaction and spray drying in glass preparation. The pre acid-base reaction was induced by prior mixing of the glass powder with poly(alkenoic acid). The weight ratios of glass powder to poly(alkenoic acid) were varied to investigate the extent of the pre acid-base reaction of the glass. The effect of the spray drying process which produced spherical glass particles on cement strength was also studied and discussed. The results show that adding 2%-wt of poly(alkenoic acid) liquid in the pre-reacted step improved cement strength. GICs prepared using a mixture of pre-reacted glass with both spherical and irregular powders at 60:40 by weight exhibited the highest compressive strength at 138.64±7.73 MPa. It was concluded that glass ionomer cements containing pre-reacted glass with mixed glass morphology using both spherical and irregular forms are promising as restorative dental materials with improved mechanical properties and handling characteristics.

A technique combining gel-casting and freeze drying methods is introduced to prepare porous hydroxyapatite scaffolds which allow for better control of the scaffold microstructure and have improved mechanical properties. A monomeric system which is known to be a suitable gelling agent for setting ceramic suspensions into dense forms was selected to produce ceramic foams. Different concentrations of sodium lauryl sulphate solution were added into the hydroxyapatite gel suspension as a pore former. The effect of the solid content on the mechanical properties of the scaffold was also investigated. Rapid freezing with liquid nitrogen was performed according to the freeze drying technique and the porous structure and morphology of the scaffolds were analyzed by scanning electron microscopy. The mechanical properties of the hydroxyapatite scaffolds were determined by testing compressive strength using a universal testing machine. The prepared scaffolds were characterized by well-defined pore connectivity along with directional, uniform and completely open porosity. The maximum compressive strength of about 17 MPa obtained from the suspension consisted of 50% solid content with 20% concentration of sodium lauryl sulphate solution. The results show that sodium lauryl sulphate solution plays a significant role in changing the pore structure of hydroxyapaite scaffolds in systems having high solid content.

Universal base is a man-made residue that can be incorporated into the DNA double strands without any discrimination against natural bases (A, C, G, T). The MD simulations with AMBER99 force field were employed to investigate the structure and dynamics of the modified 15-mer DNA duplexes containing carbazole-derived universal bases: carbazole (CBZ), 3,6-dicyanocarbazole (DCC), 3,6-dinitrocarbazole (DNC), and 3-nitro-6-cyanocarbazole (NCC), where X = CBZ, DCC, DNC, or NCC, respectively. The RMSD and B-factor of the modified DNAs backbones around the universal base unit fluctuate more than the reference sequence in the same position. The thermodynamic parameter for duplex stability was estimated by using MM-PBSA method. The averaged duplex formation free energy (ΔG) of all modified DNAs exhibited that the stability order was approximately DNC>NCC>CBZ>DCC, which differed from the reference sequence exceptional DNC unit. The averaged ΔG value of the DNC unit is very close to that of the reference sequence. This calculation indicated that the DNC unit can be considered as a good candidate for using as a universal base.