Synthesis,crystallographic characterization,and mechanical behavior of alumina chromia alloys

Powder mixtures of Alumina and Chromia, blended in different proportions (1, 3, 5 and 10%wt) by attrition milling, were fired either by pressureless sintering in air and hot pressing under vacuum. The resulting materials, characterized by X-ray diffraction, Raman spectroscopy, SEM, hardness and fracture toughness showed that all the compositions form complete solid solution which maintain the same crystal structures of corundum; chromia addition retards materials' densification of pressureless fired samples but not that of hot-pressed samples. Data from Raman spectroscopy and SEM/EDXS showed the appearance of Ti- and Mn-based impurities near the indentation print, in particular on fractured grains. The addition of chromia improves hardness, but does not affect toughness which is, on the other hand, greatly influenced by materials’ residual porosity.     

Cover Image,Volume 93, Issue 5

The cover image, by Gustavo Acosta‐Santoyo et al., is based on the Research Article Stimulation of the germination and growth of different plant species using an electric field treatment with IrO₂‐Ta₂O₅|Ti electrodes, DOI: 10.1002/jctb.5517 .

     

Study of cellular architecture and micromechanical properties of cuajilote fruits (Parmentiera edulis D.C.) using different microscopy techniques

The cuajilote (Parmentiera edulis D.C.) tree produces fibrous fruits with a high content of lignocellulosic compounds. However, this fruit and their fibers have been scarcely studied. For this reason, an integral study of their cellular architecture, physicochemical, micromechanical, and structural properties in two maturity stages were carried out. Physicochemical tests, light, confocal and electron microscopy, microindentation, and X‐ray diffraction were used for the characterization of fruit and their fibers. Chemical analysis showed that the unripe fruits have the highest cellulose content (42.17%), but in ripe fruit the cellulose content decreases (32.76%) while lignin content increases from 35.26 to 40.79%, caused by the lignification of the sclerenchyma fibers. Microstructural and micromechanical studies in the different regions of the fruit provided relevant information about its cellular architecture, distribution of lignocellulosic compounds and its role in the micromechanical properties of their fibers. The thickening cell wall of sclerenchyma fibers was caused by the cellular lignification of the ripe fruits. According to the physicochemical and structural studies, cuajilote fibers are comparable to other fibers obtained from crops rich in lignocellulosic compounds. The current study provided new knowledge about the cellular architecture of fruit and criteria for selecting the ripening stage adequate for the extraction of cellulose or lignin. Furthermore, information regarding the micromechanical properties of their fibers and which structural arrangement could be more convenient for mechanical reinforcement of biodegradable materials was obtained.     

How fish oils could support our friendly bacteria

Commensal gut bacteria are generally considered to be friendly bacteria, since they can help their host in numerous ways. These can include breaking down undigested food to produce metabolites (by‐products), which can be a fuel source for gut cells and can help to regulate the immune system, amongst many other beneficial functions that support the host's health. Probiotic bacteria are bacteria that offer a benefit to their host. They are used in dietary supplements and many are of the genus Lactobacilli. We tested whether gut cells respond differently to a commensal bacterium (Lactobacillus gasseri) and two pathogenic bacteria (Escherichia coli and Staphylococcus aureus), and also whether the responses could be altered with PUFAs. We used a cell co‐culture model containing a layer of colorectal cells, with immune cells in a porous compartment beneath. This model represents the outer cell lining of our lower gut and the immune cells that sit underneath in an area called the lamina propria. We showed that commensal L. gasseri increased the secretion of the immune signalling protein TGF‐β1 (Transforming Growth Factor β1), along with increased expression of its encoding gene signal. TGF‐β1 has an important role in promoting tolerance towards commensal bacteria and has a role in dampening immune responses following inflammation. The pathogenic bacteria had no effect on the amount of TGF‐β1. Our results indicate that L. gasseri could have a way of promoting its own survival in the gut by inducing tolerance towards itself, an effect which pathogenic bacteria do not have. When eicosapentaenoic acid was added to the cell culture model along with L. gasseri, there was a greater increase in TGF‐β1 gene expression. This early research shows the potential of combining fish oil with probiotic bacteria to promote probiotic survival in the gut and/or dampening inflammatory responses.     

Glucuronidation of curcuminoids by human microsomal and recombinant UDP-glucuronosyltransferases

Glucuronidation is an important pathway in the metabolism of curcumin, but the isoforms of uridine-5'-diphosphoglucuronosyltransferase (UGT) involved are not known. Here, we report on the glucuronidation of the three natural curcuminoids and their major phase I metabolites with microsomes from human liver and intestine as well as with human recombinant UGTs. Microsomes from human liver generated predominantly the phenolic and small amounts of the alcoholic glucuronide of each curcuminoid, whereas intestinal microsomes formed only the phenolic conjugates but with higher activities. The phenolic glucuronidation of the curcuminoids was predominantly catalyzed by hepatic UGT1A1 and intestinal UGT1A8 and 1A10, whereas UGT1A9, 2B7, and 1A8 exhibited high activities for hexahydro-curcuminoids. UGT1A9 was able to form the alcoholic glucuronide of each curcuminoid in addition to the phenolic conjugate. These data suggest that the gastrointestinal tract contributes substantially to the glucuronidation of curcuminoids in humans, which may have important implications for their pharmacokinetic fate in vivo.     

Design of correlation filters for recognition of linearly distorted objects in linearly degraded scenes

Generalized correlation filters are proposed to improve recognition of a linearly distorted object embedded in a nonoverlapping background when the input scene is degraded with a linear system and additive noise. Several performance criteria defined for the nonoverlapping signal model are used for the design of filters. The derived filters take into account information about an object to be recognized, disjoint background, noise, and linear degradations of the target and the input scene. Computer simulation results obtained with the proposed filters are discussed and compared with those of various correlation filters in terms of discrimination capability, location errors, and tolerance to input noise.     

Use of linear programming to calculate dwell times for the design of petal tools

Two constraints in the design of a petal tool are, the angles that define it must all be positive, and wear must never be greater than the desired wear. The first constraint is equivalent to that of the positive dwell times of a small solid tool. In view of this foregoing, we present a design of petal tools that are used to generate conic surfaces from their nearest spheres and that correct the profile of a surface that is polished. We study optimal angular sizes of a petal tool, which are found after we use linear programming to calculate the optimal dwell times of a set of complete annular tools placed in different zones of the glass surface. We report numerical results of designed petal tools.     

Dietary Counseling and Probiotic Supplementation During Pregnancy Modify Placental Phospholipid Fatty Acids

It has previously been shown that maternal nutrition affects the fetal environment, with consequences for the infant’s health. From early pregnancy onwards participants here received a combination of dietary counseling and probiotics (Lactobacillus GG and Bifidobacterium lactis Bb12; n = 10), dietary counseling with placebo (n = 12), or placebo alone (n = 8). The major differences in placental fatty acids were attributable to a higher concentration of n-3 polyunsaturated fatty acids in both intervention arms than in controls. Further, dietary counseling with probiotics resulted in higher concentrations of linoleic (18:2n-6) and dihomo-γ-linolenic acids (20:3n-6) compared with dietary counseling with placebo or controls. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.