Roberto M. Narbaitz

PURIFICATION AND IMMUNOCHEMISTRY OF A SOLUBLE MATRIX PROTEIN OF THE CHICKEN EGGSHELL (OVOCLEIDIN 17)

The protein components of biomineralized structures (matrix proteins) are believed to modulate crystal nucleation and growth, and theraby influence the shape and strength of the final structure. The chicken eggshell contains a complex array of distinct matrix proteins. The most abundant of these was purified to homogeneity by a combination of anionic exchange and hydroxyapatite chromatographies. Antibodies to this protein were raised in rabbit, and utilized for Western blotting and immunohistochemistry. These studies indicated that the 17 kDa antigen (ovocleidin 17, OC-17) is found in the shell gland mucosa, and that only the tubular gland cells were positive. Immunohistochemistry with decalcified shell indicated that OC-17 is uniformly distributed throughout the shell matrix, but concentrated in the mammillary bodies. Our results indicate that this protein is secreted during shell formation and becomes incorporated into this structure. It may therefore play a role in the crystallization process and influence the properties of the resulting eggshell.

Autoradiographic localization of target cells for 1α, 25-dihydroxyvitamin D3 in bones from fetal rats

SummaryThaw-mount autoradiographic studies after injection of3H-1,25-D3 were conducted on 18-and 20-day-old rat fetuses. In maxillary bones, ribs, and tibia, nuclear concentration of radioactivity was found in osteoprogenitor cells and osteoblasts. Osteocytes and chondrocytes in epiphyseal plates were either unlabeled or weakly labeled. In competition experiments, nuclear concentration of radioactivity was blocked by the injection of a high dose of nonradioactive 1,25-D3 prior to the administration of the labeled hormone, but not by a similar dose of nonradioactive 25-D3. The results are interpreted as indicating that osteoprogenitor cells and osteoblasts are target cells for the direct action of 1,25-D3 on fetal bone.

Estrogen receptors in the fetal mouse

Abstract [ 3 H]-diethylstilbestrol has been injected into pregnant mice on day 16 of pregnancy. Autoradiograms were prepared from fetal tissues as well as maternal brain. Radioactivity is found to be concentrated in the male and female fetus in nuclei of cells in certain hypothalamic and extrahypothalamic brain regions, in the anterior pituitary, in laryngeal mesenchyme, in mesenchyme that surrounds the genital tracts, the urogenital sinus, the rectum and the mammary glands, in the gubernaculum testis, and in the skin. The results suggest presence of estrogen receptors in these structures and estrogenic actions at these sites.

Electrochemical regeneration of granular activated carbon

Abstract Laboratory experiments investigated the feasibility of a novel granular activated carbon (GAC) regeneration technique: electrochemical regeneration. GAC was loaded with phenol, via batch adsorption tests, then electrochemically regenerated and finally reloaded with phenol. Regeneration was conducted in a batch reactor filled with a 1 % NaCl solution as the electrolyte. As limited experiments showed that cathodic regeneration was 5–10% more efficient than anodic regeneration, the investigation concentrated on the former. Although anodic regeneration was more efficient in destroying phenol residuals from the electrolyte, cathodic regeneration could also eliminate these residuals by using longer regeneration times and/or higher currents. Increasing the regeneration current to 100 mA for 5 hours can increase the regeneration efficiency (RE) to a maximum of 95%. Lower currents applied for longer regeneration times can yield similar results. REs were also significantly affected by the electrolyte type, the electrolyte concentration, and the GAC particle size, but not by the phenol loadings. Multiple regenerations only reduce the REs an additional 2% per cycle. Given the high regeneration efficiencies and no apparent carbon losses, electrochemical regeneration of GAC at a laboratory-scale is a feasible alternative to thermal regeneration and merits further investigation.

Application of surface modifying macromolecules in polyethersulfone membranes : Influence on PES surface chemistry and physical properties

Novel surface modifying macromolecules (SMMs) were developed for incorporation into polyethersulfone (PES) membranes, intended for pervaporation applications. These materials were synthesized with a diisocyanate, polypropylene oxide (PPO), and a fluoro-alcohol, and characterized for elemental analysis, molecular weight, and glass transition temperatures. PES/SMM blends with eight types of SMMs were characterized for surface and physical properties and compared with PES. Water droplet contact angle measurements and X-ray photoelectron spectroscopy data showed that the SMMs migrated to the surface and rendered the PES material more hydrophobic. While advancing contact angle data were equivalent to those of pure Teflon™, the highest average values of receding angles of these systems were less than those of commercial Teflon™. The opaqueness of PES/SMMs films and data from differential scanning calorimetry experiments showed that the SMMs were either immiscible or only partially miscible with PES. It was also observed, for a fixed PES concentration of 25 wt %, that increases in the molecular weight of the SMMs and the weight fraction of PPO in the SMMs led to phase separation in the ternary PES/SMMs/dimethylacetamide (i.e., membrane casting solution) system. On the other hand, in the binary PES/SMMs system (i.e., cast membrane film), an increasing weight fraction of fluorine in the SMMs contributed to an increase in the phase separation.

Electrochemical regeneration of granular activated carbons loaded with phenol and natural organic matter

The main objective of this study was to assess the performance of electrochemical regeneration of granular activated carbon via a set of bench‐scale experiments using different operating conditions in the regeneration of several different activated carbons loaded with phenol or natural organic matter. The regeneration efficiency can be increased by increasing the charge applied, whether this was achieved by an increase in current or regeneration time. The degree of phenol‐adsorption saturation did not significantly affect the regeneration efficiencies. The regeneration efficiencies of the various types of phenol‐loaded activated carbon were quite similar despite the differences in their conductivity. The activated carbon exhibiting fully reversible adsorption of phenol had slightly higher regeneration efficiencies than those involving partially irreversible adsorption. Electrochemical regeneration of activated carbon is feasible at a laboratory scale as regeneration efficiencies up to 80% were achieved during electrochemical regeneration of phenol‐loaded or natural organic matter‐loaded activated carbons.

Soluble protein constituents of the domestic fowl's eggshell

1. The protein components of the domestic fowls eggshell are believed to influence appreciably the mechanical properties of the shell and/or its biomineralisation. The purpose of this study was to compare the protein species composing the eggshell matrix in different parts of the shell structure, by SDS-PAGE and chromatography, utilising eggshell cleaned by different methodologies. 2. Protein species were identified whose absence was associated with the removal of the mammillary knobs. In particular, a prominent 81 kDa protein, as well as 38 and 54 kDa calcium-binding proteins, were concentrated within the mammillary layer, as was a 129 kDa insoluble protein. By contrast, soluble proteins of 54, 33, 22, and 14 kDa were enriched in the palisade layer. 3. Our results demonstrate that the mineralised layers of the fowls eggshell possess a complex array of distinct proteins. The different proteins which have been detected in the mammillary and palisade layers may be related to the distinct crystallisation patterns of calcium carbonate in these zones of the eggshell.

Electrochemical regeneration of field spent GAC from two water treatment plants

The effectiveness of on-site thermal regeneration of field-spent granular activated carbon (GAC) from two municipal drinking water facilities was compared with bench-scale electrochemical regeneration, a novel regeneration technology. The regeneration method was evaluated using aqueous natural organic material (NOM) adsorption, iodine number analysis, and surface area analysis. In contrast to the large electrochemical regeneration efficiencies reported in the literature for GAC loaded with phenolics and other individual organic compounds, the electrochemical reactor tested was only able to regenerate 8-15% of the NOM adsorption capacity of the field spent GAC. In contrast, thermal reactivation achieved up to 103% regeneration efficiency. To more accurately assess the efficiency of regeneration processes for water treatment applications, GAC should be loaded in continuous-flow columns and not batch rectors. The iodine number analysis yielded higher efficiency values, however it did not give an accurate estimate of the regeneration efficiency. The small changes in GAC pore size distribution were consistent with the low electrochemical regeneration efficiencies. These low efficiencies appear to be related to the low reversibility of NOM adsorption and to pH-induced adsorbate desorption being the primary mechanism for this type of electrochemical regeneration system.

Mass transport in the membrane air-stripping process using microporous polypropylene hollow fibers: effect of toluene in aqueous feed☆

Abstract Membrane air-stripping (MAS), using microporous polypropylene hollow fiber membrane modules, is one of the most promising processes for removal and recovery of volatile organic compounds (VOCs) from water/wastewater. In this work, aqueous feed containing VOCs was allowed to cross-flow on the shell side, whereas air flowed through the lumen of fibers. Chloroform, toluene and their mixture were used as model VOCs. The effects of presence of toluene alone and in mixture with chloroform in aqueous feed on the mass transport of VOCs through the membrane are reported. It was found that Henry’s law constants (HLCs) for toluene as well as chloroform did not change significantly in mixtures. The tests showed that higher toluene adsorption than that of chloroform on the fibers. It appeared that toluene blocked the pores partially, due to its strong affinity for the membrane material, resulting in substantially reduced mass transport.

Impact of pH on the adsorption and desorption kinetics of 2-nitrophenol on activated carbons

The adsorption and desorption kinetics of 2-nitrophenol (2NP) from aqueous solutions using F-400 and WV-B granular activated carbons (GAC) have been studied at pHs 1, 4.6 and 13, using batch tests. Adsorption and desorption kinetics of 2NP on to both carbons were adequately described by the homogeneous solid surface diffusion model (HSSD). The adsorption and desorption kinetics can be predicted at different pHs by using adsorption kinetics parameters of the pH 4.6 and the isotherm parameters for the corresponding pH. Thus, the differences in the rates of adsorption are primarily attributable to the differences in the equilibrium loadings at the various pHs.