Inhibition of Listeria monocytogenes by oregano, cranberry and sodium lactate combination in broth and cooked ground beef systems and likely mode of action through proline metabolism

Listeria monocytogenes is a food safety challenge in various food systems including fresh and frozen meat and poultry. Natural antimicrobials from plant sources in combination with salts of organic acids have the potential to control L. monocytogenes. In this research the efficiency of water soluble phenolic extracts of oregano and cranberry in combination with sodium lactate was evaluated for control of L .monocytogenes. In both broth and cooked meat studies, the results indicated that the combination of water soluble extracts of oregano and cranberry, at a ratio of 50:50 and a concentration of 750 ppm, with 2% sodium lactate had the best inhibitory effect in the tested strain. Based on the rationale that phenolics in oregano and cranberry behave as proline analogs, the potential recovery of pathogen growth in medium with the best inhibitor concentration and supplemented with 1 mM proline was evaluated. The results indicated that there was a proline-induced growth recovery, pointing to a possible mechanism of action of inhibitors, involving proline metabolism. These results confirm the potential of plant extracts to be antimicrobial, and when combined with sodium lactate, can be used as a nature constituent of multiple-barrier food preservation systems.     

Increased Autotaxin Levels in Severe COVID-19, Correlating with IL-6 Levels,Endothelial Dysfunction Biomarkers,and Impaired Functions of Dendritic Cells

Autotaxin (ATX; ENPP2) is a secreted lysophospholipase D catalyzing the extracellular production of lysophosphatidic acid (LPA), a pleiotropic signaling phospholipid. Genetic and pharmacologic studies have previously established a pathologic role for ATX and LPA signaling in pulmonary injury, inflammation, and fibrosis. Here, increased ENPP2 mRNA levels were detected in immune cells from nasopharyngeal swab samples of COVID-19 patients, and increased ATX serum levels were found in severe COVID-19 patients. ATX serum levels correlated with the corresponding increased serum levels of IL-6 and endothelial damage biomarkers, suggesting an interplay of the ATX/LPA axis with hyperinflammation and the associated vascular dysfunction in COVID-19. Accordingly, dexamethasone (Dex) treatment of mechanically ventilated patients reduced ATX levels, as shown in two independent cohorts, indicating that the therapeutic benefits of Dex include the suppression of ATX. Moreover, large scale analysis of multiple single cell RNA sequencing datasets revealed the expression landscape of ENPP2 in COVID-19 and further suggested a role for ATX in the homeostasis of dendritic cells, which exhibit both numerical and functional deficits in COVID-19. Therefore, ATX has likely a multifunctional role in COVID-19 pathogenesis, suggesting that its pharmacological targeting might represent an additional therapeutic option, both during and after hospitalization.     

Purification and characterization of chymosin and pepsin from kid

The objective of this work was to study the characteristics of the gastric aspartic proteinases chymosin and pepsin which are constituents of the kid rennet. The two enzymes were extracted from abomasal tissue of one kid from a local indigenous breed, separated from each other by DEAE-cellulose chromatography and then were purified by gel filtration and anion-exchange chromatography. The molecular weights of the purified kid chymosin and pepsin as determined by gel filtration were 36 kDa and 40 kDa respectively. The isoelectric point of kid chymosin was as multiple forms of 3-6 zones at pH 4.6-5.1, while that of kid pepsin was at pH < or =3.0. Kid pepsin contained 0.37 molecules phosphorous per molecule and was totally inhibited by 5 muM pepstatin A, being more sensitive than kid chymosin. Both enzymes were almost equally as proteolytic as calf chymosin on total casein at pH 5.6. Kid pepsin activity was more pH and temperature dependent than kid chymosin activity. In comparison with the calf chymosin temperature sensitivity, the order of increased sensitivity was: calf chymosin 相似文献   

Design of a Prototype EHD Air Pump for Electronic Chip Cooling Applications

This paper presents the design,optimization and fabrication of an EHD air pump intended for high-power electronic chip cooling applications.Suitable high-voltage electrode configurations were selected and studied,in terms of the characteristics of the generated electric field,which play an important role in ionic wind flow.For this purpose,dedicated software is used to implement finite element analysis.Critical design parameters,such as the electric field intensity,wind velocity,current flow and power consumption are investigated.Two different laboratory prototypes are fabricated and their performances experimentally assessed.This procedure leads to the fabrication of a final prototype,which is then tested as a replacement of a typical fan for cooling a high power density electronic chip.To assist towards that end,an experimental thermal testing setup is designed and constructed to simulate the size of a personal computer’s CPU core of variable power.The parametric study leads to the fabrication of experimental single-stage EHD pumps,the optimal design of which is capable of delivering an air flow of 51 CFM with an operating voltage of 10.5 kV.Finally,the theoretical and experimental results are evaluated and potential applications are proposed.     

Age determination of highly enriched uranium: separation and analysis of 231Pa

An analytical procedure has been developed for the age determination of highly enriched uranium samples exploiting the mother/daughter pair 235U/231Pa. Protactinium is separated from bulk uranium through highly selective sorption to silica gel and is subsequently quantified using alpha-spectrometry. The method has been validated using uranium standard reference materials of known ages. It affords decontamination factors exceeding 2.5 x 10(7), overall recoveries in the range of 80-85%, and a combined uncertainty below 5%.     

Three-dimensional simulations of light propagation in periodic liquid-crystal microstructures

A composite scheme based on the finite-difference time-domain method and a plane-wave expansion method is developed and applied to the optics of periodic liquid-crystal microstructures. This is used to investigate three-dimensional light-wave propagation in grating-induced bistable nematic devices with double periodicity. Detailed models of realistic devices are analyzed with emphasis on two different underlying surface-relief grating structures: a smooth bisinusoidal grating and a square-post array. The influence of the grating feature size is quantified. Device performance is examined in conjunction with an appropriate compensation layer, and the optimum layer thickness is determined for the different grating geometries.     

Palliation of large-bowel obstruction due to recurrent rectosigmoid tumor using self-expandable endoprostheses

STUDY DESIGN: This study assessed the variability of segmental bone mineral density in the lower cervical spine (C4 through C7). A mean segmental bone mineral density value at each level was determined for all specimens, and a mean coefficient of variation among the 17 specimens was calculated. OBJECTIVES: To quantify the degree of intersegmental bone mineral density variations within cadaveric lower cervical spine segments. SUMMARY OF BACKGROUND DATA: Bone mineral density studies in the thoracic and lumbar spine have shown a high degree of variability between spinal segments; however, the extent of segmental bone mineral density variability in the cervical spine is unknown. METHODS: Seventeen human cadaveric cervical spine specimens (C4 through C7) were scanned in a water bath using dual energy x-ray absorptiometry in a lateral direction. Segmental bone mineral density of the vertebral bodies of all specimens were analyzed with respect to differences between segments within each specimen. RESULTS: The mean coefficient of segmental bone mineral density variations within each specimen for all spines was 14.8% (range, 5.8%-22.9%). Bone mineral density mean values and ranges at each level were as follows: C4, 0.720 g/cm2 (range, 0.367-1.161 g/cm2); C5, 0.784 g/cm2 (range, 0.348-1.268 g/cm2); C6, 0.735 g/cm2 (range 0.367-1.450 g/cm2); C7, 0.590 g/cm2 (range, 0.340-1.040 g/cm2). Paired analysis of difference between all levels for 16 specimens demonstrated the bone mineral density at the C7 level to be significantly lower than at all other levels (P < 0.05). CONCLUSION: Our data show that significant interlevel bone mineral density variability exists in the lower cervical spine, and suggests that random single segment bone mineral density sampling or mean specimen bone mineral density values may not be relevant.     

Endoscopic drainage of acute obstructive cholecystitis in patients with increased operative risk

Emergency biliary surgery for acute obstructive cholecystitis in the elderly is associated with an increased hospital mortality. We therefore attempted to drain the obstructed gallbladder via the transpapillary route in 18 patients (mean age: 67 years) who had cystic duct obstruction on ERC and who were at an increased surgical risk. A cholecystonasal catheter was successfully introduced after a small EPT in sixteen of them (89%). This resulted in effective bile drainage, obviating the need for emergency surgery in all patients. No procedure-associated morbidity or mortality was found. Following clinical remission, elective treatment consisted of ESWL/direct stone dissolution (n = 10) or elective surgery (n = 3). Three patients received no further therapy. Our results show that endoscopic gallbladder drainage may be a valuable alternative to emergency surgery in high risk patients with acute obstructive cholecystitis.     

The kinetics of the sulphuric acid leaching of nickel and magnesium from reduction roasted serpentine

Nickel may be extracted with partial selectivity over magnesium from laterites containing serpentine by reduction roasting followed by sulphuric acid leaching. This paper describes the results of a kinetic study of the sulphuric acid leaching of nickel and magnesium from the reduction roasted serpentine component of a typical laterite. The serpentine used in this work analyzed 1.65% nickel, 20.2% magnesium and 6.10% iron.Initially, leaches were carried out at temperatures of 30, 50 and 70° C to determine the acid requirement for complete nickel extraction using practical leaching conditions (25% solids) under which the acidity drops to a low level. A minimum acid addition of 60 g/l was needed, which gave 80% to 83% nickel extraction from material in which 85% of the nickel was reduced using hydrogen at 700° C. Under these conditions, about 17% of the magnesium was leached at each of the temperatures studied.To facilitate an understanding of leaching kinetics, leaches were then performed using constant acidities (0.1% solids) of 60, 30 and 15 g/l acid at temperatures of 30, 50 and 70° C. Closely sized particles (?65 + 100 mesh) were leached so that magnesium dissolution rates could be tested against established “shrinking core” models.The main conclusions are that, under the experimental conditions, nickel dissolution rates were chemically controlled by either $\text{2}\text{H}{}^{\mathrm{+}}\text{+}\text{1}\text{2}\text{O}{}_2\text{+ 2e →}\text{H}{}_2\text{O}$ or 2 H⁺ + 2e → H₂ occurring at the surfaces of the 40% nickel/iron alloy platelets formed during reduction. The rate controlling process had an activation energy of 11kcal/mole.During extraction of metallic nickel, the dissolution of magnesium follows a “shrinking core” kinetic model, which assumes the reaction is unimpeded by a surface layer of silica - a reaction product. Rates of magnesium dissolution during this stage of the reaction (up to 25% dissolved) were chemically controlled with an activation energy of 12 kcal/mole.At magnesium extractions above 25%, at which point all the metallic nickel had been extracted, the rate of silicate attack was limited by diffusion through a silica coating attached to particle surfaces.The results indicate that selectivity for nickel dissolution over that of magnesium does not depend strongly on acidity and temperature at the levels investigated.     

Thorium/uranium mixed oxide nanocrystals: Synthesis, structural characterization and magnetic properties

One of the primary aims of the actinide community within nanoscience is to develop a good understanding similar to what is currently the case for stable elements. As a consequence, efficient, reliable and versatile synthesis techniques dedicated to the formation of new actinide-based nano-objects （e.g., nanocrystals） are necessary. Hence, a ＂library＂ dedicated to the preparation of various actinidebased nanoscale building blocks is currently being developed. Nanoscale building blocks with tunable sizes, shapes and compositions are of prime importance. So far, the non-aqueous synthesis method in highly coordinating organic media is the only approach which has demonstrated the capability to provide size and shape control of actinide-based nanocrystals （both for thorium and uranium, and recently extended to neptunium and plutonium）. In this paper, we demonstrate that the non-aqueous approach is also well adapted to control the chemical composition of the nanocrystals obtained when mixing two different actinides. Indeed, the controlled hot co-injection of thorium acetylacetonate and uranyl acetate （together with additional capping agents） into benzyl ether can be used to synthesize thorium/uranium mixed oxide nanocrystals covering the full compositional spectrum. Additionally, we found that both size and shape are modified as a function of the thorium：uranium ratio. Finally, the magnetic properties of the different thorium/uranium mixed oxide nanocrystals were investigated. Contrary to several reports, we did not observe any ferromagnetic behavior. As a consequence, ferromagnetism cannot be described as a universal feature of nanocrystals of non-magnetic oxides as recently claimed in the literature.