Towards optimization of the osmotic drying process of alumina-gelatin objects: Regression analysis and verification

In this study, further analysis of the osmotic drying process was conducted to identify the optimum combination of parameters for drying rectangular alumina-gelatin beams. This study was designed to determine the effect of three variables related to the osmotic drying process (osmotic pressure, molecular weight, and immersion time) on the interaction between the liquid desiccant and the submerged alumina-gelatin samples. The water loss from the alumina-gelatin samples was positively correlated with the molecular weight, osmotic pressure, and immersion time. Up to 40% by weight of the initial water content was removed during the osmotic drying process. The samples also experienced solids gain due to the counterflow of solute from the liquid desiccant. The least amount of solids gain resulted from drying for the shortest immersion time at low osmotic pressure and high molecular weight. Evidence of possible interactions between variables was noted for the sintered density metric. Statistical methods were used to form regression equations for the measured responses (water loss, solids gain, bulk density). A verification experiment was conducted to compare the experimental outcomes to the predicted outcomes. The responses were simultaneously optimized to identify the combination of variable settings required to meet specified goals. In order to maximize water loss, minimize solids gain, and maximize bulk density, the ceramic-gelatin object should be immersed for approximately 60?min in an aqueous solution of 100,000?g/mol poly(ethylene oxide) at an osmotic pressure of 2.50?MPa. These values are valid for the range of parameter settings tested and the sample fabrication and drying methods used.     

Synthesis and Application of Novel Nano Fe-BTC/GO Composites as Highly Efficient Photocatalysts in the Dye Degradation

Topics in Catalysis - Nano Fe-BTC/graphene oxide (GO) composites were successfully synthesized by hydrothermal treatment with a microwave-assisted method. Samples were characterized by X-ray...     

CuInS2/SiNWs/Si composite material for application as potential photoelectrode for photoelectrochemical hydrogen generation

This work aims at developing a new composite material based on nanosized semiconducting CuInS₂ (CIS) particles combined with silicon nanowires grown on a silicon substrate (SiNWs/Si) for photoelectrochemical (PEC)-splitting of water. The CIS particles were prepared via a colloidal method using N-methylimidazole (NMI) as the solvent and an annealing treatment. The SiNWs were obtained by chemical etching of silicon (100) substrates assisted by a metal. The CIS/SiNWs/Si composite material was obtained by deposition of an aliquot of a suspension of CIS particles onto the SiNWs/Si substrate, using spin coating followed by a drying step. The XRD pattern demonstrated that CuInS₂ grows in the tetragonal/chalcopyrite phase, while SiNWs/Si presents a cubic structure. The SEM images show semi-spherical particles (～10 nm) distributed on the surface of silicon nanowires (～10 μm). The EIS measurements reveal n-type conductivity for CIS, SiNWs/Si and CIS/SiNWs/Si materials, which could favour the oxidation reaction of water molecules.     

Molten salt synthesis of MAX phases in the Ti-Al-C system

The molten salt method was used to synthesise the MAX phase compounds Ti₂AlC and Ti₃AlC₂ from elemental powders. Between 900–1000?°C, Ti₂AlC was formed alongside ancillary phases TiC and TiAl, which decreased in abundance with increasing synthesis temperature. Changing the stoichiometry and increasing the synthesis temperature to 1300?°C resulted in formation of Ti₃AlC₂ alongside Ti₂AlC and TiC. The type of salt flux used had little effect on the product formation. The reaction pathway for Ti₂AlC was determined to be the initial formation of TiC_1-x templating on the graphite and titanium aluminides.     

Performance Analysis of Pulse Generators on Residual Stress of Machined Silicon Steel Using the EDM Process

The cracks in the workpiece specimens can reduce the fatigue life of any machine components. Since the residual stress has a considerable amount of influence on determining crack formation over the machined surface, it is very essential to analyze the residual stress developed in any machining process. However, it is a very tedious process to compute the residual stress over the machined surface. In the present study, an endeavor has been made to measure and analyze the residual stress of machined silicon steel as a workpiece using the EDM process with different energy distribution. The nano-indentation method was used to compute the residual stress produced over the machined surface. From the experimental results, it was found that the uniform energy distribution has produced higher compressive residual stress owing to the tiny and uniform spark energy distribution. It has also been observed that the tool electrode has a considerable amount of influence on determining development of residual stress in the EDM process.     

Prediction of rock mass P wave velocity using blasthole drilling information

In this paper, the development of the models for the prediction of rock mass P wave velocity is presented. For model development, the database of 53 cases including widely used and recorded drilling parameters and P wave velocity was constructed from the field studies conducted in 13 open pit lignite mines. Both conventional linear, non-linear multiple regression and Adaptive Neuro Fuzzy Inference System (ANFIS) were used for model development. Prediction performance indicators showed that ANFIS model presented the best performance and it can successfully be used for the preliminary prediction of P wave velocities of rock masses.     

Preparation of highly crystalline titanium-based ceramic microfibers from polymer precursor blend by needle-less electrospinning

The aim of the present contribution is to study the influence of the post-spinning heat - treatment of single TiO₂/PVP precursor fibers on the properties and morphology of the final titanium-based microfibers. The post-spinning treatment conditions were: calcination in air at 450–600?°C and pyrolysis in argon at 1000–1700?°C. Calcination resulted in a production of anatase-rich and pure rutile fibers. The use of an alternative sintering method, the low-temperature plasma treatment, led to the crystallization of the composite Magnéli phases/polymer fibers. As a result of the same one precursor, pyrolysis at 1000?°C, the Carbon/TiO₂ composite fibers were obtained. Rising the treatment temperature in inert atmosphere led to the formation of the titanium carbide fibers. The formation process and all the obtained products were characterized by differential scanning calorimetry accompanied with thermogravimetric analysis (DSC/TGA), scanning and transmission electron microscopy (SEM, TEM), X-ray diffraction (XRD), and image analysis techniques.     

Antitumor Effects of Vitamin D Analogs on Hamster and Mouse Melanoma Cell Lines in Relation to Melanin Pigmentation

Deregulated melanogenesis is involved in melanomagenesis and melanoma progression and resistance to therapy. Vitamin D analogs have anti-melanoma activity. While the hypercalcaemic effect of the active form of Vitamin D (1,25(OH)₂D₃) limits its therapeutic use, novel Vitamin D analogs with a modified side chain demonstrate low calcaemic activity. We therefore examined the effect of secosteroidal analogs, both classic (1,25(OH)₂D₃ and 25(OH)D₃), and novel relatively non-calcemic ones (20(OH)D₃, calcipotriol, 21(OH)pD, pD and 20(OH)pL), on proliferation, colony formation in monolayer and soft-agar, and mRNA and protein expression by melanoma cells. Murine B16-F10 and hamster Bomirski Ab cell lines were shown to be effective models to study how melanogenesis affects anti-melanoma treatment. Novel Vitamin D analogs with a short side-chain and lumisterol-like 20(OH)pL efficiently inhibited rodent melanoma growth. Moderate pigmentation sensitized rodent melanoma cells towards Vitamin D analogs, and altered expression of key genes involved in Vitamin D signaling, which was opposite to the effect on heavily pigmented cells. Interestingly, melanogenesis inhibited ligand-induced Vitamin D receptor translocation and ligand-induced expression of VDR and CYP24A1 genes. These findings indicate that melanogenesis can affect the anti-melanoma activity of Vitamin D analogs in a complex manner.     

Temperature cycling and its effect on mechanical behaviours of highporosity chalks

Temperature history can have a significant effect on the strength of water-saturated chalk.In this study,hydrostatic stress cycles are applied to understand the mechanical response of chalk samples exposed to temperature cycling between each stress cycle,compared to the samples tested at a constant temperature.The total accumulated strain during a stress cycle and the irreversible strain are reported.Chalk samples from Kansas(USA)and Mons(Belgium),with different degrees of induration(i.e.amount of contact cementation),were used.The samples were saturated with equilibrated water(polar)and nonpolar Isopar H oil to quantify water weakening.All samples tested during 10 stress cycles with varying temperature(i.e.temperature cycled in between each stress cycle)accumulated more strain than those tested at constant temperatures.All the stress cycles were performed at 30℃.The two chalk types behaved similarly when saturated with Isopar H oil,but differently when saturated with water.When saturated with water,the stronger Kansas chalk accumulated more total strain and more irreversible strain within each stress cycle than the weaker Mons chalk.