Surface Defect Mitigation of Additively Manufactured Parts Using Surfactant-Mediated Electroless Nickel Coatings.

The emergence of defects during the early production phases of ferrous-alloy additively manufactured (AM) parts poses a serious threat to their versatility and adversely impacts their overall mechanical performance in industries ranging from aerospace engineering to medicine. Lack of fusion and gas entrapment during the manufacturing stages leads to increased surface roughness and porosities in the finished part. In this study, the efficacy of employing electroless nickel-boron (Ni-B) deposition to fill and level simulated AM defects was evaluated. The approach to levelling was inspired by the electrochemical deposition techniques used to fill vias in the electronics industry that (to some extent) resemble the size and shape of AM-type defects. This work investigated the use of surfactants to attenuate surface roughness in electroless nickel coatings, thereby achieving the preferential inhibition of the coating thickness on the surface and promoting the filling of the simulated defects. A cationic surfactant molecule, CTAB (cetyltrimethyl ammonium bromide), and a nonpolar surfactant, PEG (polyethylene glycol), at different concentrations were tested using a Ni-B electrolyte for the levelling study. It was found that the use of electroless Ni-B to fill simulated defects on ferrous alloys was strongly influenced by the concentration and nature of the surfactant. The highest levelling percentages were obtained for the heavy-molecular-weight PEG-mediated coatings at 1.2 g/L. The results suggest that electroless Ni-B deposition could be a novel and facile approach to filling defects in ferrous-based AM parts.

Using fish scales as a new biosorbent for adsorption of nickel and copper ions from wastewater and investigating the effects of electric and magnetic fields on the adsorption process.

In this study, fish scales (Pomadasys kaakan's scales) were used as new biosorbent for removing Ni2+ and Cu2+ ions from wastewater. The effects of electric and magnetic fields on the absorption efficiency were also investigated. The effects of sorbent content, ion concentration, contact time, pH, electric field (EF), and magnetic field (MF) on absorption efficiency were assertained. In addition, the isotherm of absorption was studied in this work. This study revealed that electric field and magnetic field have significant effects on the absorption efficiency of ions from wastewater. An increase in the electric field enhanced the removal percentage of the ions and accelerated the absorption process by up to 40% in comparison with the same condition without an electric field or a magnetic field. By increasing contact time from 10 to 120 min, the removal of Ni2+ ions was increased from 1% to 40% and for Cu2+ ions, the removal increased from 20% to almost 95%, respectively. In addition, increasing pH, ion concentration and scales dose increased removal percentage effectively. The results indicated that using fish scales for Cu2+ ions absorption is ideal due to the very high removal percentage (approximately 95%) without using either an electric or magnetic field.

Waste electrical and electronic equipments as urban mines in Burkina Faso: Characterization and release of metal particles.

Like other developing countries, Burkina Faso is one of the preferential destinations for second-hand electrical and electronic equipments (EEE). At the end of their life, these EEEs are classified as waste electrical and electronic equipment (WEEE) including Printed Circuit Boards (PCB). A particle size reduction is realized for the release of metals by shredding and grinding to obtain particles smaller 1.5 mm. A granulometric sorting was realized and nine granulometric portions were obtained. Particles were characterized by optical microscopy and Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy (EDS). The experiments confirmed that the fractions contained polymers, glass fibers and metals under the form of single metals or alloys. The release of metal was efficient for particles with a size smaller than 0.71 mm. Three digestion procedures were experimented on four components to assess the impact on metals leaching. Microwave-assisted digestion method was the best procedure, compared to the analysis methods ISO 11466: 1995, and method 3050B, adapted. The characterization by Inductively coupled plasma atomic emission spectroscopy (ICP-AES) of these PCBs exhibited important amounts of precious metals (Ag, Au, Pd) and other metals in greater quantities (Cu, Pb, Ni, Co, etc.), leading to their qualification as "Urban Mines" calling for their recovery. The characterization of metals in each granulometric portion is realized. Precious and others metals were distributed in all granulometric size portions. So granulometric size reduction was not efficient for metal separation and recovery from PCBs and alternative methods should be investigated for selective precious metal recovery.

Identification of Dlk1-Dio3 imprinted gene cluster noncoding RNAs as novel candidate biomarkers for liver tumor promotion.

The molecular events during nongenotoxic carcinogenesis and their temporal order are poorly understood but thought to include long-lasting perturbations of gene expression. Here, we have investigated the temporal sequence of molecular and pathological perturbations at early stages of phenobarbital (PB) mediated liver tumor promotion in vivo. Molecular profiling (mRNA, microRNA [miRNA], DNA methylation, and proteins) of mouse liver during 13 weeks of PB treatment revealed progressive increases in hepatic expression of long noncoding RNAs and miRNAs originating from the Dlk1-Dio3 imprinted gene cluster, a locus that has recently been associated with stem cell pluripotency in mice and various neoplasms in humans. PB induction of the Dlk1-Dio3 cluster noncoding RNA (ncRNA) Meg3 was localized to glutamine synthetase-positive hypertrophic perivenous hepatocytes, suggesting a role for ß-catenin signaling in the dysregulation of Dlk1-Dio3 ncRNAs. The carcinogenic relevance of Dlk1-Dio3 locus ncRNA induction was further supported by in vivo genetic dependence on constitutive androstane receptor and ß-catenin pathways. Our data identify Dlk1-Dio3 ncRNAs as novel candidate early biomarkers for mouse liver tumor promotion and provide new opportunities for assessing the carcinogenic potential of novel compounds.