Solution growth of spherulitic rod and platelet calcium phosphate assemblies through polymer-assisted mesoscopic transformations

Solution growth of apatite its precursors in the presence of urea commercial gelatin is found to lead, under appropriate conditions, to a rich spectrum of morphologies, among them high aspect ratio needles in uniform sturdy spherulitic assemblies resulting from a herein documented morphological ‘Chrysalis Transformation’; the latter transformation involves the growth of parallel arrays of high aspect ratio needles within micron-scale tablets the formation of a radial needle arrangement upon disruption of tablet wrapping. A different level of gelatin leads to the formation of sturdy platelet-based spherulites through another morphological transformation. We also probe the role of four simple synthetic water-soluble polymers; we find that three of them (poly(vinyl alcohol), polyvinylpyrrolidone and polyacrylamide)) also affect substantially the assembly habits of apatite; the effect is similar to that of gelatin but the attained control is less perfect/complete. The case of poly(vinyl alcohol) provides, through variation of the degree of hydrolysis, insights as regards the chain architecture features that might favor morphological transformations. Morphological transformations of particle assemblies documented herein constitute novel ways of generating dense quasi-isotropic reinforcements with high aspect ratio ceramic particles; it becomes possible to tailor calcium phosphate phases at the structural level of crystal assembly.     

Effects of 2-ethylhexanoic acid on reproduction and postnatal development in Wistar rats

Reproductive toxicity of 2-ethylhexanoic acid (2-EHA) was studied in Wistar rats. The animals (24 animals per sex per group) were given 2-EHA as a sodium salt in drinking water at daily doses of 100, 300, or 600 mg/kg. Control animals received plain water. Male rats were exposed to 2-EHA for 10 weeks and females for 2 weeks prior to mating, both sexes during the mating period and females during the entire gestation and lactation period. 2-EHA caused a slight but dose-dependent decrease in fertility; time to mating increased at 300 and 600 mg/kg and even total infertility ensued. 2-EHA slightly decreased sperm quality in males. The spermatozoa were significantly less motile at 100 and 600 mg/kg and abnormal sperm occurred more frequently at the two highest dose levels. The average litter size was reduced by 16% in the dose group receiving 600 mg/kg. The birth weights of the pups were unaffected but the body weight gain was transiently slower during lactation at 600 mg/kg. Several pups appeared abnormal (kinky tail, lethargic, slightly paralyzed legs) and the physical development assessed by several landmarks (opening of eyes, eruption of teeth, hair growth) and reflexes (grip reflex, cliff avoidance) was delayed at 300 and 600 mg/kg. In another experiment, a single dose of 600 mg/kg 2-EHA was given to pregnant females by gavage on Gestational Day 4, 5, 6, or 7 and the number of implantations were counted on Gestational Day 10. Administration on Day 6 decreased the number of implantations and caused resorptions.(ABSTRACT TRUNCATED AT 250 WORDS)     

Synthesis of a neoglycoprotein containing the Lewis X analogous trisaccharide beta-D-GalpNAc-(1-->4)[alpha-L-Fucp-(1-->3)]-beta-D-GlcpNAc

The trisaccharide allyl glycoside 36 and related disaccharide part structures have been prepared using the 2-trichloroacetamido-2-deoxy-alpha-D-galactopyranosyl trichloroacetimidate derivative 9 as glycosyl donor under promotion with TMSOTf or Sn(OTf)2, respectively, to produce the beta-(1-->4) linkage to suitably protected glucosamine derivatives in fair yields. Fucosylation was effected employing the ethyl 1-thio glycosyl donor 20 in the presence of IDCP. Deprotection of the intermediates afforded the disaccharide allyl glycosides beta-D-GalpNAc-(1-->4)- beta-D-GlcpNAc 13, beta-D-GalpNClAc-(1-->4)-beta-D-GlcpNAc 14, alpha-L-Fucp-(1-->3)-beta-D-GlcpNAc 24, alpha-L-Fucp-(1-->4)-beta-D- GlcpNAc 31 and the branched trisaccharide allyl glycoside beta-D-GalpNAc-(1-->4)[alpha-L-Fucp-(1-->3)]-beta-D-GlcpNAc 36. The trisaccharide which corresponds to a structural motif occurring in N-glycoprotein glycans from human urokinase, human recombinant protein C, phospholipase A2 as well as O-glycans, was converted into a neoglycoprotein following introduction of a cysteamine-derived spacer group and subsequent activation with thiophosgene.     

Indolylfuran,a potent aryl hydrocarbon receptor agonist from sauerkraut,interacts with the oestrogen pathway

Numerous ligands of the aryl hydrocarbon receptor (AhR) have been found in plants, especially edible plants, such as cruciferous vegetables, which exert beneficent health effects. A potent activator of the AhR was found in sauerkraut juice. The isolated active ingredient was identified as the novel AhR ligand, (1-(2-furanyl)2-(3-indolyl)ethanone, common name indolylfuran. The isolated and the synthesised compound exerted similar potencies; their EC₅₀-values in an AhR transactivation assay were 160 and 123 nM, respectively. Our in vivo studies confirm and enlighten basic interactions between the AhR and oestrogen receptors (ERs). Further anti-oestrogenic effects of sauerkraut extract were shown. Indolylfuran regulates ER α and β expression, most likely via the AhR pathway, since indolylfuran had no effect on uterus weight and did not agonise ERα. Sauerkraut and indolylfuran may have potential for the prevention or treatment of diseases through modulation of AhR regulation and, indirectly, the ER pathway.     

Characterization of Seed,Oil, and Fatty Acid Methyl Esters of an Ethyl Methanesulfonate Mutant of Camelina sativa with Reduced Seed-Coat Mucilage

Camelina sativa L. Crantz (large-seeded false flax) is a promising oilseed crop for the production of edible oil and biodiesel. An ethyl methanesulfonate (EMS) mutant of C. sativa was identified that lacked seed coat mucilage (SCM) using Ruthenium Red (RR) colorimetric staining. Compared with wild-type (WT) plants, the mucilage-defect mutant line (Cs98) had smaller seeds and seeds with significantly less SCM, but exhibited significantly taller plant height. The seed mass and oil content of the seeds of Cs98 were significantly lower than those of WT plants. However, the seeds of Cs98 had significantly higher crude protein and starch contents, but a significantly lower neutral detergent-soluble fiber (NDSF) fraction (pectin) content. Although Cs98 seed contained significantly higher mineral contents for various macro- and microminerals (e.g., Mg, S, Al, Cu, Mn, Fe, and Zn), these large differences did not prevent the Cs98 seed biodiesel from passing all American Society for Testing and Materials (ASTM) standards for macro- and micromineral content and viscosity, pH, and turbidity. Notably, the oil and biodiesel derived from Cs98 had significantly reduced viscosity compared with WT. Water washes of oil derived from WT and Cs98 seed confirmed that the Cs98 contained only 57% of the mucilage content of the WT oil washes. These significantly lower pectic residues are expected to improve the flow characteristics of the resultant oil and require less washing during biodiesel production.     

Rheological properties of re-melted paraffin-wax suspensions used for LPIM

The influence of re-melting of suspensions of ceramic powder and paraffin-wax used for LPIM on the yield stress and the flow behaviour was investigated. As a model system we used alumina powder and paraffin-wax, which has a liquid/solid phase transition at around 58 °C. The only parameter that was changed during this study was the number of particles per unit volume and, consequently, the number of attractive, interparticle interactions in the suspensions per unit volume.During cooling the particles took up closer interparticle distances than in the prepared suspension due to the huge shrinkage associated with paraffin-wax, which occurs below the liquid–solid phase transition. This resulted in an increased, attractive interparticle interaction (and so an increased yield stress) and an increase in the strength of attractive particle network formed after re-melting, which can be destroyed by homogenization, as was shown during the flow-curve measurements, and the initial flow properties of the paraffin-wax suspensions can be regained.     

Weakly Flocculated Aqueous Alumina Suspensions Prepared by the Addition of Mg(II) Ions

Well-dispersed aqueous alumina suspensions were prepared at an inherent pH via the addition of an anionic dispersant. With the addition of an appropriate amount of magnesium acetate to such a suspension, the surface charge of the particles was neutralized, which was reflected in the destabilization of the slurry. Because of the formation of coordinative bonds between the Mg ion and the two dissociated carboxylic groups of the dispersant, a thin neutral layer was formed on the surface of the particles, which established a nontouching particle network and resulted in a weakly flocculated suspension.     

Structural requirements of synthetic oligosaccharides to bind monoclonal antibodies against Chlamydia lipopolysaccharide

Monoclonal antibodies were generated against a synthetic glycoconjugate containing the trisaccharide alpha-Kdo-(2-->8)-alpha-Kdo-(2-->4)-alpha-Kdo (Kdo, 3-deoxy-D-manno-2-octulopyranosonic acid) which represents the genus-specific epitope of the lipopolysaccharide from the obligatory intracellular human pathogen Chlamydia. Antibodies of all immunoglobulin G isotypes were obtained and characterized by enzyme immunobinding and inhibition assays using the immunizing antigen as well as chemically synthesized derivatives of the Kdo trisaccharide. The latter contained (1) one of the three residues in beta- instead of alpha-linkage, (2) a Kdo residue the carboxyl group of which had been reduced to a CH2OH group (Kdo(C1-red)), or (3) changing the linkage of the terminal Kdo from 2-->8 to 2-->4. Only one compound, namely, alpha-Kdo-(2-->8)-alpha-Kdo(C1-red)-(2-->4)-alpha-Kdo exhibited binding to and inhibition of Kdo trisaccharide-specific antibodies, whereas all other compounds were not active. Structural and conformational investigations using NMR spectroscopy at high field on the allyl glycosides of the oligosaccharides 6-12 confirmed the conformational similarities between those structures 4, 5, and 10 which were able to bind to the antibodies investigated.     

Fibrous hydroxyapatite–carbon nanotube composites by chemical vapor deposition: In situ fabrication,structural and morphological characterization

Fibrous hydroxyapatite (HA)–carbon nanotube composites were synthesized by the catalytic decomposition of acetylene over Fe–Co bimetallic catalysts supported on the fibrous HA. Two forms of fibrous HA (distinct needle-like monocrystals and spherulitic aggregates of needles) were synthesized using a simple precipitation method and loaded with bimetallic catalysts (from 2 up to 20 wt%) by a wet chemical impregnation method. The HA supported catalysts were evaluated for the in situ growth of carbon nanotubes using the catalytic chemical vapor deposition method. The effect of reaction temperature and metal loading on the yield, structural perfection and morphology of the carbon products were investigated using a combination of X-ray diffraction, thermal analysis, Raman spectroscopy and scanning and transmission electron microscopies. The results revealed that both the selection of the growing conditions and the metal loading determine the yield and overall quality of the synthesized carbon nanotubes, which exhibit high graphitization degree when synthesized in high yields.     

Suppressed Reactivity of AlN Powder in Water at 5°C

The hydrolysis behavior of AlN powder suspensions (5–25 wt%) at 5°C has been investigated to explore the impact of low temperatures on the hydrolysis behavior. Throughout the 312‐h long experiment, the pH value of the suspensions was below 9, where the hydrolysis remained in the induction period and was eventually suppressed due to the formation of a few‐nanometers‐thick film of amorphous aluminum hydroxide gel around the AlN particles, acting as a passivation layer. Moreover, the aqueous part of the suspension possessed a remarkably high value of dissolved [Al(III)]_aq, being an order of magnitude higher at a given pH value than the aqueous AlCl₃ solution.