Polymer-derived ceramic molten metal filters

Journal of Materials Science - This paper reports the synthesis and the performance of polymer-derived ceramic filters for molten metal filtration. Two different filter types were studied: foam...     

Comparison of restorative materials and surface alterations after prebiotic and probiotic beverages: A nanoindentation and SEM study

The purpose was to investigate the surface characteristics of various resin-based materials by immersing in probiotic beverages. A total of 420 disc-shaped samples (5 mm × 2 mm) were prepared from resin-based composites. Samples were divided into four groups and immersed for 10 min/day for 1 month in either a probiotic sachet, kefir, kombucha, or artificial saliva (control). Surface roughness was measured at baseline and 1 month. One sample of each of the tested materials was examined under nanoindentation to evaluate the reduced elasticity modulus and nanohardness scores. Scanning electron microscopy (SEM) was used to compare surface differences. Data were analyzed statistically using one-way ANOVA test and the significance was set at p < .05. The lowest roughness scores were observed in Z250, Estelite Bulk Fill, and HRi ENA in most of the test groups. Among conventional composites, Z250 group had the highest nanohardness and elasticity modulus scores. Among bulk-fill composites, Estelite Bulk Fill Flow had the lowest surface roughness after immersion in probiotic beverages and the highest nanohardness values. Reveal HD, as a bulk-fill group showed higher surface roughness and considerably lower nanohardness and elasticity modulus scores. Maximum height levels of samples were recorded. SEM images revealed voids and microcracks on the surfaces of test materials. Dentists may prefer Z250 as microhybrid and Estelite Bulk Fill Flow as bulk-fill composites for the restorations of patients who consume gut-friendly drinks regularly. When there are various types of materials, nanoindentation is a useful method for evaluating surface alterations and sensible comparisons.     

Closed porosity ceramics and glasses

In the last three decades, considerable effort has been devoted to obtain both open and closed porosity ceramics & glasses in order to benefit from unique combination of properties such as mechanical strength, thermal and chemical stability at low-relative density. Most of these investigations were directed to the production and the analysis of the properties for open porosity materials, and regrettably quite a few compositions and manufacturing methods were documented for closed porosity ceramics & glasses in the scientific literature so far. This review focuses on the processing strategies, the properties and the applications of closed porosity ceramics & glasses with total porosity higher than 25%. The ones below such level are intentionally left out and the paper is set out to demonstrate the porous components with deliberately generated closed pores/cells. The processing strategies are categorized into five different groups, namely sacrificial templating, high-temperature bonding of hollow structures, casting, direct foaming, and emulsions. The principles underlying these methods are given, with particular emphasis on the critical issues that affect the pore characteristics, mechanical, thermal and electrical properties of the produced components.     

Tough and hierarchical porous cryogel scaffolds preparation using n-butanol as a non-solvent

Hierarchical porous chitosan cryogels were prepared by combination of cryogelation and phase separation techniques. n-Butanol was included as a non-solvent in the initial polymer solutions to enable phase separation. The internal morphology of the resulting cryogels revealed hierarchical porosity where larger pores of between 25–50?µm were formed via cryogelation, whereas smaller pores of between 4–10?µm were produced by phase separation. The control sample prepared without n-butanol exhibited monotype porosity. Any crack development was not observed when samples were compressed up to 80% strain. The results demonstrated hierarchical porous and tough scaffolds with potential use in tissue engineering.     

Adaptive active appearance models.

The active appearance model (AAM) is a powerful tool for modeling images of deformable objects and has been successfully used in a variety of alignment, tracking, and recognition applications. AAM uses subspace-based deformable models to represent the images of a certain object class. In general, fitting such complicated models to previously unseen images using standard optimization techniques is a computationally complex task because the gradient matrix has to be numerically computed at every iteration. The critical feature of AAM is a fast convergence scheme which assumes that the gradient matrix is fixed around the optimal coefficients for all images. Our work in this paper starts with the observation that such a fixed gradient matrix inevitably specializes to a certain region in the texture space, and the fixed gradient matrix is not a good estimate of the actual gradient as the target texture moves away from this region. Hence, we propose an adaptive AAM algorithm that linearly adapts the gradient matrix according to the composition of the target image's texture to obtain a better estimate for the actual gradient. We show that the adaptive AAM significantly outperforms the basic AAM, especially in images that are particularly challenging for the basic algorithm. In terms of speed and accuracy, the idea of a linearly adaptive gradient matrix presented in this paper provides an interesting compromise between a standard optimization technique that recomputes the gradient at every iteration and the fixed gradient matrix approach of the basic AAM.     

Effect of High Hydrostatic Pressure Treatment (HHPT) on Quality and Shelf Life of Atlantic Mackerel (Scomber scombrus)

The ability of high hydrostatic pressure treatment (HHPT) to extend the shelf life of Atlantic mackerel (Scomber scombrus) was assessed in this study. For that purpose, fillets were subjected to pressure treatments at 200, 300, 400 MPa at 5, 10, 15 °C for 5 and 15 min. The influence of pressure treatments on the levels of trimethylamine nitrogen (TMA-N) and thiobarbituric acid (TBA) as well as color changes was investigated. The suitable combinations were determined as 200 MPa, 15 °C for 5 min. and 400 MPa, 5 °C for 5 min. In the second stage, the shelf life of samples, which were treated at these conditions, stored at 4?±?0.5 °C were studied by monitoring pH, color, sensorial features (appearance and odor), TMA-N, TBA, total volatile basic nitrogen, histamine, and total mesophilic aerobic count. The unpressurized mackerel samples were acceptable up to only 7 days compared to 17 and 19 days after 200 and 400 MPa treatments; respectively. The results obtained in this study showed that HHPT in combination with chilled storage can improve the shelf life and quality of fish.     

Versatile p(3-sulfopropyl methacrylate) hydrogel reactor for the preparation of Co,Ni nanoparticles and their use in hydrogen production

In this study, polymeric hydrogels derived from 3-sulfopropyl methacrylate (SPM) were used in the preparation of composite-catalyst system in hydrogen generation from hydrolysis of NaBH₄. In order to generate pores and determine their effect on hydrogen production, silica based p(SPM) hydrogels were synthesized also prepared. Additionally, the effects of metal type, temperature, the amount of the catalyst, metal reloading, and reusability were investigated. The activation energy, activation enthalpy, and activation entropy for the hydroylsis reaction of NaBH₄ solution in the presence of p(SPM)–Co catalyst system were calculated as 41.67 kJ mol^?1, 38.15 kJ mol^?1, ?173.139 J/mol K, respectively.     

用大粒径同位素测井技术测定吸水剖面

对于注水开发油田,通常使用放射性同位素测井测量注水井的吸水剖面。但由于不同地层其孔喉半径不同、受注入水的冲刷程度不同,当向井内注入粒径较小的放射性同位素载体后,对部分孔喉半径大、受注入水的冲刷程度严重的井,其小粒径同位素载体不是滤积在井壁附近,而是注入到探测器无法探测到的远离井筒部位,造成测量结果失真。通过改用大粒径同位素载体测量吸水剖面,不但可以提高资料的准确度,而且可以更明确地划分吸水层位。