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21.

Background

Pseudomonas aeruginosa adhesion to animal/human cells for infection establishment involves adhesive proteins, including its galactose- and fucose-binding lectins PA-IL (LecA) and PA-IIL (LecB). The lectin binding to the target-cell receptors may be blocked by compatible glycans that compete with those of the receptors, functioning as anti-adhesion glycodecoys. The anti-adhesion treatment is of the utmost importance for abrogating devastating antibiotic-resistant P. aeruginosa infections in immunodeficient and cystic fibrosis (CF) patients. This strategy functions in nature in protecting embryos and neonates. We have shown that PA-IL, PA-IIL, and also CV-IIL (a PA-IIL homolog produced in the related pathogen Chromobacterium violaceum) are highly useful for revealing natural glycodecoys that surround embryos in diverse avian eggs and are supplied to neonates in milks and royal jelly. In the present study, these lectins were used as probes to search for seed embryo-protecting glycodecoys.

Methods

The lectin-blocking glycodecoy activities were shown by the hemagglutination-inhibition test. Lectin-binding glycoproteins were detected by Western blotting with peroxidase-labeled lectins.

Results

The present work reports the finding - by using PA-IL, PA-IIL, and CV-IIL - of rich glycodecoy activities of low (< 10 KDa) and high MW (> 10 kDa) compounds (including glycoproteins) in extracts of cashew, cocoa, coffee, pumpkin, and tomato seeds, resembling those of avian egg whites, mammal milks, and royal jelly.

Conclusions

Edible seed extracts possess lectin-blocking glycodecoys that might protect their embryos from infections and also might be useful for hampering human and animal infections.  相似文献   
22.
Although single-hole oscillatory columns have been studied since the 1990s, to this day there is an absence of appropriate dimensionless groups to express the hydrodynamic conditions and power requirement for the moving-baffle oscillatory baffled column (OBC). This paper uses computational fluid dynamic (CFD) software coupled with moving overset meshing to aid in the derivation of the first dimensionless oscillatory power number for OBCs. In terms of the moving-baffle OBC, this work marks the first time a power density equation has been derived specifically to account for this column's unique hydrodynamic profile. Equations for period-averaged Reynolds number and period-averaged Strouhal numbers were developed to better estimate the fluid intensity within these moving-baffle columns. This work serves as an example of how complex and challenging flow regimes, such as periodically oscillating flow, can be simplified and analyzed to produce appropriate design equations.  相似文献   
23.
The objective of this work is to prepare absorbent materials based on polydimethylsiloxane (PDMS) for the absorption of organic solvents by a relative simple method, with large absorption capacities and reusability. Different particles (ZnO, MgSO4, ZnCl2, and NaHCO3) were first incorporated in PDMS and then removed by immersion in HCl (c) or water. The absorbent materials were characterized by TGA, mercury porosimetry, stress–strain curves, SEM, EDS, XPS, FTIR, and water contact angle. The materials can absorb polar organic chlorinated solvents (carbon tetrachloride, dichloroethene, dichloromethane, and chloroform) more than four times its own weight. Other solvents were also tested showing 2–3 times its own weight. Additionally, these materials show demulsification properties and absorption of oleophilic compounds. The reusability of the material makes them good candidates for remediation of polluted water.  相似文献   
24.
In this study, NiTi–x wt.% B4C (x = 0, 2, and 4) composites were consolidated with spark plasma sintering method, and the effects of boron carbide reinforcement addition on the microstructure and wear behavior of samples were investigated. Identification of the constituent phases of samples by the X-ray diffraction method plus Rietveld analysis revealed that the stability of the martensite phase increased in the composite samples because of mismatch stresses between the NiTi matrix phase and the reinforcing particles, which increases the density of the dislocations and facilitates the diffusion process that subsequently leads to the formation of stable intermetallics. The results of hardness test indicated that the hardness value increased from 3.67 GPa for pure NiTi to 10.99 GPa for NiTi–4 wt.% B4C. Results of wear test revealed that boron carbide reinforced composite specimens had higher wear resistance, whereas wear rate of NiTi sample was 3.6 × 10−3 mm3/N m, and it reached to .21 × 10−3 mm3/N m for NiTi–4 wt.% B4C. Investigation of microstructure by scanning electron microscopy images and EDS analysis revealed that the wear mechanism in NiTi samples was abrasive and the addition of B4C to NiTi changed the wear mechanisms from abrasive to a combination of oxidation, adhesive, and delamination mechanisms.  相似文献   
25.
Altering the association properties of insulin by amino acid replacement   总被引:12,自引:0,他引:12  
The importance of ProB28 and LysB29 on the self-associationof insulin was established by systematically truncating theC terminus of the B chain. The relationship between structureand association was further explored by making numerous aminoacid replacements at B28 and B29 Association was studied bycircular dichroism, size-exclusion chromatography and ultracentrifugation.Our results show that the location of a prolyl residue at B28is critical for high-affinity self-association. Removal of ProB28in a series of C-terminal truncated insulins, or amino acidreplacement of Pro28, greatly reduced association. The largestdisruption to association was achieved by replacing LysB29 withPro and varying the amino acid at B28 Several of the analogswere predominantly monomers in solutions up to 3 mg/ml. Theseamino acid substitutions decreased association by primarilydisrupting the formation of dimers. Such amino acid substitutionsalso substantially reduced the Zn-induced insulin hexamer formation.The formation of monomeric insulins through amino acid replacementswas accompanied by conformational changes that may be the causefor decreased association. It is demonstrated that self-associationof insulin can be drastically altered by substitution of oneor two key amino acids.  相似文献   
26.
Lignin‐based chemicals, starch, and urea were used as modifiers for phenol–formaldehyde resol resins. The effects of the addition stage of the modifiers used in the synthesis of the resins and the type of modification reagent on the structures of the resins and their molar masses and reactivities were investigated. The modifications with corn starch and lignin promoted condensation; this was verified by increased molar masses and high ratios of methylene bridges to the sum of free ortho and para aromatic groups with respect to the corresponding reference resin without a modification reagent. The later the modifier was added to the resin condensation mixture, the more methylene bridges were formed with respect to the amounts of free ortho and para aromatic groups. In addition, when urea or wheat starch was added in the later condensation stage, the final condensation also reached high stages. The modifications with lignosulfonate and starch, as well as the early addition of urea, enhanced pp′ bridge structures. The lowest condensation stage and, therefore, the highest reactivity were found when wheat starch was added with the starting reagents. The curing heat of the wheat‐starch‐modified resins decreased according to the deferred addition point of starch. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 582–588, 2003  相似文献   
27.
Summary: This paper discusses static and dynamic mechanical properties of electron beam‐cured mixtures made of the nematic liquid crystal (LC) E7 and either tripropyleneglycol diacrylate (TPGDA) or propoxylated glycerol triacrylate (GPTA) as monomers differing essentially by their functionality. Dilution of the initial mixture with LC leads to a significant weakening of the film mechanical strength. Strong effects were found on Young modulus and rubbery state modulus. As the concentration of LC increases, these mechanical parameters drop significantly together with the glass transition temperature of the polymer showing a plasticizing effect. The results for the glass transition temperatures for the polymer and the LC were confirmed by thermograms obtained by differential scanning calorimetry.

Storage tensile modulus versus temperature of EB‐cured TPGDA/E7 films for different LC concentrations.  相似文献   

28.
Vulcanized composites of chloroprene rubber (CR) with cellulose II (Cel II) as a filler were investigated. Cel II, obtained by the coagulation of cellulose xanthate, was incorporated in the rubber by the traditional method. The filler content varied from 0 to 30 phr. For comparison purposes, carbon black (CB)–CR composites were also studied. The CB amount varied from 0 to 45 phr. The mechanical and dynamic mechanical properties were determined, and the CR composite containing 20 phr of Cel II showed the best set of properties. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2425–2430, 2004  相似文献   
29.
Catalytic paraffin dehydrogenation for manufacturing olefins is considered to be one of the most significant production routes in the petrochemical industries. A reactor kinetic model for the dehydrogenation of propane to propylene in a radial‐flow reactor over Pt‐Sn/Al2O3 as the catalyst was investigated here. The model showed that the catalyst activity was highly time dependent. In addition, the component concentrations and the temperature varied along the reactor radius owing to the occurring endothermic reaction. Moreover, a similar trend was noticed for the propane conversion as for the propylene selectivity, with both of them decreasing over the time period studied. Furthermore, a reversal of this trend was also revealed when the feed temperature was enhanced or when argon was added into the feed as an inert gas.  相似文献   
30.
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