Quantifying evolving toxicity in the TAML/peroxide mineralization of propranolol.

Oxidative water purification of micropollutants (MPs) can proceed via toxic intermediates calling for procedures for connecting degrading chemical mixtures to evolving toxicity. Herein, we introduce a method for projecting evolving toxicity onto composite changing pollutant and intermediate concentrations illustrated through the TAML/HO mineralization of the common drug and MP, propranolol. The approach consists of identifying the key intermediates along the decomposition pathway (UPLC/GCMS/NMR/UV-Vis), determining for each by simulation and experiment the rate constants for both catalytic and noncatalytic oxidations and converting the resulting predicted concentration versus time profiles to evolving composite toxicity exemplified using zebrafish lethality data.

Additively Manufactured Continuous Cell-Size Gradient Porous Scaffolds: Pore Characteristics, Mechanical Properties and Biological Responses In Vitro.

Porous scaffolds with graded open porosity combining a morphology similar to that of bone with mechanical and biological properties are becoming an attractive candidate for bone grafts. In this work, scaffolds with a continuous cell-size gradient were studied from the aspects of pore properties, mechanical properties and bio-functional properties. Using a mathematical method named triply periodic minimal surfaces (TPMS), uniform and graded scaffolds with Gyroid and Diamond units were manufactured by selective laser melting (SLM) with Ti-6Al-4V, followed by micro-computer tomography (CT) reconstruction, mechanical testing and in vitro evaluation.

Study on the Geometric Design of Supports for Overhanging Structures Fabricated by Selective Laser Melting.

Additional structures are usually adopted to support the overhanging structures in order to resist the deformation of parts. Improper geometric design of the support structures may result in a sharp deterioration in the surface quality and a failure of manufacture, which affects the expansion in the use of selective laser melting (SLM) technology. In this research, cuboids were added into the conventional block support for a better heat dissipation.

Improved Mechanical Properties and Energy Absorption of BCC Lattice Structures with Triply Periodic Minimal Surfaces Fabricated by SLM.

The triply periodic minimal surface (TPMS) method is a novel approach for lattice design in a range of fields, such as impact protection and structural lightweighting. In this paper, we used the TPMS formula to rapidly and accurately generate the most common lattice structure, named the body centered cubic (BCC) structure, with certain volume fractions. TPMS-based and computer aided design (CAD) based BCC lattice structures with volume fractions in the range of 10⁻30% were fabricated by selective laser melting (SLM) technology with Ti⁻6Al⁻4V and subjected to compressive tests.

Finite Element Analysis of Interaction of Laser Beam with Material in Laser Metal Powder Bed Fusion Process.

A deep understanding of the laser-material interaction mechanism, characterized by laser absorption, is very important in simulating the laser metal powder bed fusion (PBF) process. This is because the laser absorption of material affects the temperature distribution, which influences the thermal stress development and the final quality of parts. In this paper, a three-dimensional finite element analysis model of heat transfer taking into account the effect of material state and phase changes on laser absorption is presented to gain insight into the absorption mechanism, and the evolution of instantaneous absorptance in the laser metal PBF process.

Mechanical Properties of Optimized Diamond Lattice Structure for Bone Scaffolds Fabricated via Selective Laser Melting.

Developments in selective laser melting (SLM) have enabled the fabrication of periodic cellular lattice structures characterized by suitable properties matching the bone tissue well and by fluid permeability from interconnected structures. These multifunctional performances are significantly affected by cell topology and constitutive properties of applied materials. In this respect, a diamond unit cell was designed in particular volume fractions corresponding to the host bone tissue and optimized with a smooth surface at nodes leading to fewer stress concentrations.

Iron(III) Ejection from a "Beheaded" TAML Activator: Catalytically Relevant Mechanistic Insight into the Deceleration of Electrophilic Processes by Electron Donors.

Kinetic studies of the acid-induced ejection of iron(III) show that the more electron-rich tetra-amido-N macrocyclic ligand (TAML) activator [Fe{(MeCNCOCMeNCO)CMe}OH] (4), which does not have a benzene ring in its head component ("beheaded" TAML), is up to 1 × 10 times more resistant than much less electron-rich [Fe{1,2-CH(NCOCMeNCO)CMe}OH] (1a) to the electrophilic attack. This counterintuitive increased resistance is seen in both the specific acid (k = k[H]/(K + [H])) and phosphate general acid (k = (kK + k[H])/(K+[H])) demetalation pathways. Insight into this reactivity puzzle was obtained from coupling kinetic data with theoretical density functional theory modeling.

Manufacturing Feasibility and Forming Properties of Cu-4Sn in Selective Laser Melting.

Copper alloys, combined with selective laser melting (SLM) technology, have attracted increasing attention in aerospace engineering, automobile, and medical fields. However, there are some difficulties in SLM forming owing to low laser absorption and excellent thermal conductivity. It is, therefore, necessary to explore a copper alloy in SLM.

A "Beheaded" TAML Activator: A Compromised Catalyst that Emphasizes the Linearity between Catalytic Activity and pK.

Studies of the new tetra-amido macrocyclic ligand (TAML) activator [Fe{(MeCNCOCMeNCO)CMe}OH] (4) in water in the pH range of 2-13 suggest its pseudo-octahedral geometry with two nonequivalent axial HO ligands and revealed (i) the anticipated basic drift of the first pK of water to 11.38 due to four electron-donating methyl groups alongside (ii) its counterintuitive enhanced resistance to acid-induced iron(III) ejection from the macrocycle. The catalytic activity of 4 in the oxidation of Orange II (S) by HO in the pH range of 7-12 is significantly lower than that of previously reported TAML activators, though it follows the common rate law (v/[Fe] = kk[HO][S]/(k[HO] + k[S]) and typical pH profiles for k and k.