Mechanical properties of the A356 aluminum alloy modified with La/Ce

The research of rare earths for the synthesis of materials with improved mechanical performance is of great interest when they are considered for potential applications in the automotive industry. In this regard, the effect on the mechanical properties and microstructure of the automotive A356 aluminum alloy reinforced with 0.2 (wt.%) Al-6Ce-3La (ACL) was investigated. The ACL was added to the melted A356 alloy in the as-received condition and processed by mechanical milling. In the second route, the effect of the ACL processed by mechanical milling and powder metallurgy techniques was investigated, and compared with the results obtained from the A356 alloy strengthened with ACL in the as-received condition. Microstructural properties were evaluated by means of X-ray diffraction in order to observe the solubility of Ce/La in the Al matrix. In addition, electron microscopy was employed in order to investigate the effect of milling time on the size and morphology of La/Ce phase under milling process. Mechanical properties of the A356 alloy modified with ACL were measured by hardness and tensile test. For comparison unmodified specimens of the A356 were characterized according to the previous procedure. The microstructural and mechanical characterization was carried out in specimens after solution and artificial aging. Observations in scanning electron microscopy indicated a homogeneous dispersion of La/Ce phases by using both routes; however, mechanical results, in the modified A356 alloy with the ACL in the as-received condition, showed an improvement in the mechanical performance of the A356 alloy over that reinforced with the ACL mechanically milled.     

Recent progress on the study of the microstructure and mechanical properties of ECAE copper

Results on the microstructure and the tensile properties of equal channel angular extruded (ECAE) copper processed for one to 16 passes are presented and compared with the available literature data. With increasing number of passes (N), the microstructure changes from a strongly elongated shear band structure after N = 1 and 2, towards a more equiaxed subgrain and grain structure. This is accompanied by a decrease in the cell wall or subgrain-boundary widths and an increase in recovered or even recrystallised grain structures with low dislocation densities. Electron backscatter diffraction measurements have indicated that for lower N, the location of Σ3 boundaries is restricted to shear bands, while at greater N, Σ3 boundaries were found to be more widely distributed. Texture measurements indicate close similarity with simple shear texture components and a spread of the orientation components with greater N. Upon comparing the tensile behaviour of as-ECAE Cu with the surveyed literature, broad agreement on the strength of the material is achieved. However, a strong variation in the percentage elongation to failure is also noted. Strain hardening and deformation kinetic analysis via strain rate jump tests indicate an evolution from stage III to V hardening during post-ECAE compression and a saturation in the strain rate sensitivity after N = 4 resulting in maximum values of ∼0.02. Our results suggest that rather than a change in deformation mechanism, the increase in ductility with increasing N is associated with an increase in the mean free path of dislocations—with the grain boundaries remaining actively involved as the transmitter of plastic strain and their interaction with dislocations being the rate controlling deformation mechanism.

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Short-term transplantation of isolated human ovarian follicles and cortical tissue into nude mice

This study was designed to evaluate follicular survival and growth after short-term transplantation of fresh isolated human follicles and ovarian cortical tissue to nude mice. Ovarian biopsies were obtained from nine women undergoing laparoscopy. Twelve nude mice were xenografted with an ovarian cortical fragment in the right ovarian bursa, and a clot containing isolated follicles in the left, for a period of 7 days. One ungrafted fragment was used as a control. Histological sections were analyzed to determine follicle number and stage. The proliferative status of follicular cells was assessed by Ki-67 immunostaining. A total of 659 follicles was analyzed by histology and 545 follicles by immunohistochemistry. The percentage of primordial follicles was found to be markedly reduced 1 week post-grafting when compared with ungrafted tissue, while the percentage of primary follicles had significantly increased. Only 8% of follicles showed Ki-67-positive granulosa cells before grafting, whereas 1 week after grafting, 71% of follicles in fragments and 67% of isolated follicles were Ki-67-positive (P<0.001). Moreover, the histological aspect of isolated follicle grafts was similar to that of grafted fragments: follicles were surrounded by vimentin-positive stroma-like tissue of human origin, as confirmed by fluorescent in situ hybridization with human-specific probes. Our results demonstrate, for the first time, that isolated human follicles are able to survive and grow after xenografting. This study also shows massive in vivo follicular activation after transplantation of grafted fragments and isolated follicles. One week after grafting, well-structured stroma-like tissue of human origin was observed around the isolated follicles. The potential origin of this stroma is discussed.     

Efficacy of chlorhexidine as a postmilking teat disinfectant for the prevention of bovine mastitis during lactation

A natural exposure trial was conducted for 12 mo in a herd of 150 lactating Jersey cows to determine efficacy of a .35% chlorhexidine teat dip containing a glycerine emollient for the prevention of bovine intramammary infections. Right teats of cows were dipped in the experimental teat dip after milking machine removal and left teats were not dipped. The herd was free of Streptococcus agalactiae and had a low prevalence of Staphylococcus aureus. Most new major pathogen intramammary infections resulted from Streptococcus species, primarily Streptococcus uberis and Streptococcus dysgalactiae. New infections by Streptococcus species were significantly lower in teats dipped in chlorhexidine than in undipped teats. Overall efficacy of the chlorhexidine teat dip against major mastitis pathogens was 50%. The experimental teat dip also reduced coagulase-negative Staphylococcus species infections 49.0% and Corynebacterium bovis infections 65.2%. Overall efficacy against minor mastitis pathogens was 54.0%. No irritation or chapping of teats dipped in the experimental teat dip was observed.     

Plasma vitellogenin levels and gonadal morphology of wild carp (Cyprinus carpio L.) in a receiving rivers downstream of sewage treatment plants

A field study was carried out in order to assess, in a wild cyprinid fish, the biological effects related to the exposure to estrogenic compounds. The gonadosomic index (GSI), plasma vitellogenin (VTG) level and histological observations of gonads were performed to evaluate the reproductive health in common carp (Cyprinus carpio) from three rivers receiving sewage treatment plant (STP) effluents (Guadarrama, Henares and Jarama rivers, Spain) and from a reference site (Lozoya river). No significative differences in male GSI between sites were described. Only in the 18% of fish from Guadarrama river were elevated plasma VTG levels detected. The presence of oocytes in the testis was not found in any of males examined. The results suggest that the released estrogenic compounds by STPs effluents are not enough capable to adversely affect the gonadal development of the fish studied. Additional studies will be required to assess the risk of estrogenic compounds on fish from other sites of this area.     

Dose effect on the uptake and accumulation of hydroxytyrosol and its metabolites in target tissues in rats

Hydroxytyrosol (HT) is the most prominent phenolic compound of virgin olive oil and due to its scientifically validated biological activities it is entering to the market as a potentially useful supplement for cardiovascular disease prevention. The aim of the present study was to investigate the relationship between the HT dose intake and its tissue uptake in rats, and thus, providing complementary information in relation to the target‐dose relationship. Rats were given a refined olive oil enriched with HT at different doses (1, 10, and 100 mg/kg) and they were sacrificed after 5 h to ensure the cell tissue uptake of HT and its metabolites. Plasma samples and different organs as liver, kidney, heart and brain were obtained, and HT metabolites were analyzed by UPLC‐MS/MS. The results showed that HT and its metabolites could be accumulated in a dose‐dependent manner basically in the liver, kidney, and brain and were detected in these tissues even at nutritionally relevant human doses. The detection of free HT in liver and kidney was noteworthy. To date, this appears to be the only biologically active form, and thus, it provides relevant information for optimizing the potential applications of HT to prevent certain hepatic and renal diseases. In recent years, HT and its derivatives have led to a great interest from the virgin olive oil producers and manufacturers of nutraceutical supplements. The increasing interest in HT is mainly due to the European Food Safety Agency (EFSA) Panel on Dietetic Products, Nutrition, and Allergies (NDA) scientific opinion that established a cause‐and‐effect relationship between the consumption of olive oil polyphenols and protection of LDL particles from oxidative damage 1 . Based on this positive opinion, the health claim “Olive oil polyphenols contribute to the protection of blood lipids from oxidative stress” was included in the list of health claims 2 , being the only authorized health claim in the European Union regarding polyphenols and health.     

Prevalence and behaviour of Bacillus cereus in a REPFED of Italian origin

This paper reports on the prevalence and behaviour of Bacillus cereus in gnocchi, a REPFED of Italian origin. A survey of gnocchi under varying storage conditions, revealed that, although B. cereus was found in 33% of the samples, the contamination level was lower than 10(2) CFU/g for the unstored and the refrigerated (8 degrees C) samples. Counts increased with increasing storage temperatures and prolonged storage times in samples prepared without sorbic acid. The effect of different formulations (sorbic, citric and lactic acid) and storage conditions (8, 12 and 20 degrees C) have been evaluated in a challenge testing with spores of B. cereus. Results indicate that the use of sorbic acid in association with citric or lactic acid to pH 5.0 is effective in inhibiting growth of B. cereus and the anticipated shelf life of the product is safe even if temperature abuse occurs. If sorbic acid is omitted, lactic acid can inhibit B. cereus growth during storage at 8 degrees C. On the contrary, when temperature abuse occurs (12 and 20 degrees C), lactic or citric acid are not able to prevent growth of B. cereus.     

Composition and characterization of soyabean and related products

Soyabean contains about 48 to 50% proteins. Among these, storage proteins are predominant. 7S and 11S globulins are two storage proteins that constitute 80% of the total protein content in soyabean. Moreover, there are other less abundant storage proteins such as 2S, 9S, and 15S globulins. In addition to globulins, enzymes, protease inhibitors (Kunitz and Bowman‐Birk), lectin, and others complete the soya protein content.

Different methods exist to characterize soya proteins. These methods involve (1) an isolation of proteins from soya commercial products and (2) the use of analytical techniques for protein determination.

Soya proteins may interact with other soya components such as minerals, phytic acid, ascorbic acid, and fiber. These interactions, which depend on soya processing and treatment, can decrease the bioavailability of minerals and proteins.

Swelling, solubility, viscosity, and capacity to form a gel, an emulsion, or a foam are the main functional properties of soyabean. They are responsible for the wide use of soya in industrial processes.     

Effect of a bacteriocin produced by Pediococcus acidilactici against Listeria monocytogenes and Clostridium perfringens on Spanish raw meat

The inhibitory effect of a bacteriocin, produced by Pediococcus acidilactici, against Listeria monocytogenes and Clostridium perfringens on Spanish raw meat surface, was evaluated by in situ assays. Samples were incubated with the bacteriocin and then with a culture of the pathogenic bacteria. The treatment with 500, 1000 or 5000 bacteriocin units/ml (BU/ml) reduced the counts of L. monocytogenes after storage at 15°C during 72h by 1, 2 or 3 log cycles and with 1000 or 5000 BU/ml after storage at 4°C during 21 days by 2.5 or 3.5 log cycles, respectively, compared to the control. With C. perfringens a bacteriostatic effect could be observed.     

Simultaneous two-dimensional endoscopic pulsed digital holography for evaluation of dynamic displacements

An endoscope is used in pulsed digital holography to simultaneously evaluate in-plane and out- of-plane transient and harmonic displacements on a flat metallic plate. The plate is illuminated from two different directions. The optical path for each illumination direction is matched to its corresponding reference beam, but also in such a way that each object-reference beam pair optical path is mismatched such that they are incoherent and can be stored in a single CCD frame. As is typical in these types of interferometric arrangement, two digital holograms are needed to compare two different states of the plate. Each hologram is Fourier transformed and due to the incoherence introduced, two separate spectra are readily identified, each belonging to an object-reference beam pair. On comparing by subtraction the phase obtained from the two pulsed digital holograms, it is possible to gather quantitative in-plane and out-of- plane results from transient and harmonic displacements.