Development of Antifouling Polysulfone Membranes by Synergistic Modification with Two Different Additives in Casting Solution and Coagulation Bath: Synperonic F108 and Polyacrylic Acid

This study deals with the development of antifouling ultrafiltration membranes based on polysulfone (PSF) for wastewater treatment and the concentration and purification of hemicellulose and lignin in the pulp and paper industry. The efficient simple and reproducible technique of PSF membrane modification to increase antifouling performance by simultaneous addition of triblock copolymer polyethylene glycol-polypropylene glycol-polyethylene glycol (Synperonic F108, Mn =14 × 103 g mol−1) to the casting solution and addition of polyacrylic acid (PAA, Mn = 250 × 103 g mol−1) to the coagulation bath is proposed for the first time. The effect of the PAA concentration in the aqueous solution on the PSF/Synperonic F108 membrane structure, surface characteristics, performance, and antifouling stability was investigated. PAA concentrations were varied from 0.35 to 2.0 wt.%. Membrane composition, structure, and topology were investigated by Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and scanning electron microscopy (SEM). The addition of PAA into the coagulation bath was revealed to cause the formation of a thicker and denser selective layer with decreasing its pore size and porosity; according to the structural characterization, an interpolymer complex of the two additives was formed on the surface of the PSF membrane. Hydrophilicity of the membrane selective layer surface was shown to increase significantly. The selective layer surface charge was found to become more negative in comparison to the reference membrane. It was shown that PSF/Synperonic F108/PAA membranes are characterized by better antifouling performance in ultrafiltration of humic acid solution and thermomechanical pulp mill (ThMP) process water. Membrane modification with PAA results in higher ThMP process water flux, fouling recovery ratio, and hemicellulose and total lignin rejection compared to the reference PSF/Synperonic F108 membrane. This suggests the possibility of applying the developed membranes for hemicellulose concentration and purification.

Thermal conditions for the formation of self-assembled cluster of droplets over the water surface

The effect of temperature profile of the water layer surface on the formation and structure of a levitating droplet cluster is studied in the paper. The laboratory experiments indicate that a local temperature maximum of water is a necessary condition for the formation of a cluster. A quantitative criterium of transformation of a monolayer of randomly positioned microdroplets to a self-assembled cluster of relatively large droplets is obtained.

The dependence of surface morphology on the growth temperature of the Pb0.7Sn0.3Te/Si(111) topological insulator thin films

The possibility of epitaxial growth of Pb0.7Sn0.3Te crystalline topological insulator films on the Si(111) surface was shown and epitaxial relations were found. It was shown that, depending on the growth temperature, it is possible to control not only the character of the morphology, but also, to a significant extent, the smoothness of the epitaxial layer surface, which is extremely important for further transport measurements of the films. Analysis of the grown films surface morphology made it possible to establish the average value of the height and lateral size of the terraces and islands forming Pb0.7Sn0.3Te surface.

Determination of the endurance limit of the surface layer of a part after processing with a blade tool

The dependences of the quality indicators of the surface layer of parts on the fatigue strength are analyzed. The dependences are given, taking into account both the quality indicators of the surface layer of the part after processing with the blade tool, and the parameters of the processing mode. Keywords: surface layer, surface roughness, residual stresses, work-hardening depth, endurance limit, blade tool processing. [email protected]

Using SiO2 nano-particles for better color uniformity and lumen output in 8500 K conformal and in-cup white LEDs

<span>In the effort of improving the performance of white light LEDs devices (WLEDs), the SiO₂ nano-particles were applied and have shown a significant impact on the optical properties. Specifically, the light output of the lighting devices is enhanced when a mixture of SiO₂ particles and silicone gel is diffused on the encapsulation layer surface. This enhancement is the result of light scattering from SiO₂ that strengthens the emitted blue light at further angles and reduces the color discrepancy. The evidence is that CCT deviation in SiO₂-doped structure decline from 1000 K to 420 K in -70° to 70°. In addition, the SiO₂ with refractive index in between the phosphor material and outside environment allows light to be emitted outward more effectively. This lighting enhancement of SiO₂-doped structure increases the lumen output by 2.25% at 120 mA power source in comparison to structure without SiO₂. These experimental outcomes suggest that SiO₂ is an effective material to add in WLEDs structure for better lighting efficiency.</span>

Active Monitoring of Selective Laser Melting Process by Training an Artificial Neural Net Classifier on Layer-By-Layer Surface Laser Profilometry Data

This paper reports some recent results related to active monitoring of Selective Laser Melting (SLM) processes through analysis of layer-by-layer surface profile data. Estimation of fault probability was carried out experimentally in a Renishaw AM250 machine, by collecting Fe3Si powder bed height data, in-situ, during the metal additive manufacturing of a Heat Exchanger section, comprised of a series of conformal channels. Specifically, high-resolution powder bed surface height data from a laser profilometer was linked to post-print ground-truth labels (faulty or nominal) for each site from CT scans, by training a shallow artificial neural net (ANN). The ANN demonstrated interesting capabilities for discovering correlations between surface roughness characteristics and the presence and size of faults. Strong performance was achieved with respect to several standard metrics for classifying faulty and nominal sites. These developments can potentially enable active monitoring processes to become a future component of a layer-by-layer feedback system for better control of SLM processes.