Role of Boron in the Tribochemistry of Thermal Films Formed in the Presence of ZnDTP and Dispersant Additives

Thermally formed, additive-derived films are often a key precursor to tribologically protective films that are formed under the influence of mechanical stress. We have examined the tribological stability of model thermal films, tested in pure base oil under severe experimental conditions. Our aim was to exclude the self-healing mechanism of the protective film, which would be expected in a fully formulated lubricant. The thermal films were grown in the presence of various oil formulations containing combinations of ZnDTP and dispersants. The films were fully characterized by means of scanning electron microscopy and atomic force microscopy (for investigating the film morphology) in combination with X-ray photoelectron spectroscopy (for determining the chemical composition and thickness of the films). The mechanical stability of the films was evaluated via a series of tribological tests carried out applying two different contact pressures, 1.04 and 0.7 GPa, in base oil—a hydro-treated, heavy paraffinic fraction known as Yubase 4—at 100 °C. The tribological tests were performed using a ball-on-disc set-up and run until the failure of the protective film occurred. It was found that boron-containing thermal films displayed a much higher mechanical stability than their boron-free counterparts. It was also shown that the presence of boron species (8.4–11.1 at.% B) in the thermal films seems to be able to limit the formation of wear particles and prolong the lifetime of the protective coatings. Furthermore, it appears that very thin, boron-based thermal films can exhibit higher durability than films that are thicker but boron-free.     

Lugaro cells target basket and stellate cells in the cerebellar cortex

Lugaro cells are fusiform neurons located just beneath the Purkinje cell layer. Their axon projects profusely in the molecular layer and emits some collaterals in the granular layer. We have analysed the molecular layer postsynaptic targets of a Golgi-impregnated Lugaro cell, using the electronmicroscopic gold-toning procedure and post-embedding anti-GABA immunocytochemistry. All the gold-labeled neuritic and somatic profiles were GABA-positive, thus confirming that the Lugaro cell is an inhibitory interneuron. The axonal varicosities of this cell form multiple symmetrical synaptic junctions with basket and stellate cell somata and proximal dendrites, and, perhaps, with the molecular layer dendrites of Golgi interneurons. Lugaro cells thus seem to exert a feed-back inhibitory control on Purkinje cells.     

Suicidal impulses in patients with chronic viral hepatitis C during or after therapy with interferon alpha

OBJECTIVE: The objective of this study was to evaluate key outcomes of a universal hearing screen/rescreen program for all births with transient evoked otoacoustic emissions in all 8 maternity hospitals in the state of Rhode Island over a 4-year period. STUDY DESIGN: This was a retrospective analysis of the hearing screen/rescreen refer data collected prospectively for 53,121 survivors born in Rhode Island between January 1, 1993, and December 31, 1996. Primary outcomes included the first-stage refer rates, rescreen compliance, diagnostic referral rates, identification rates, and the age of amplification. RESULTS: During this 4-year time period 11 infants were identified with permanent hearing loss, resulting in an impairment rate of 2 per 1000. The mean age of hearing loss confirmation decreased from 8.7 months to 3.5 months, and the age at amplification declined from 13.3 months to 5.7 months. CONCLUSION: We conclude that time and experience are important factors in the development and refinement of a universal hearing screen program. Hearing screen outcome data collected over a 4-year period in Rhode Island reveal a steady improvement in the percent of infants completing the 2-stage screen process, the stage 1 and stage 2 refer rates, compliance with rescreen and diagnostic testing, and significant improvement in the age of identification and age of amplification.     

Kinetic studies of the effects of K+, Na+ and Li+ on the catalytic activity of human erythrocyte pyridoxal kinase

Kinetic studies were conducted to examine the effects of K+, Na+ and Li+ on human erythrocyte pyridoxal kinase (PK) activity. A dialyzed hemolysate served as the PK source. The substrates used were pyridoxal (PL) and ATP. Determination of the enzymatic activity was based on HPLC separation and fluorimetric detection of PL and pyridoxal 5'-phosphate as semicarbazone derivatives. In comparison to the poor activity of PK assayed without monovalent cation, all tested cations are activators. Among them, K+ is the most effective, improving both PK affinity for the substrates and maximal velocity. Na+ increases maximal velocity and PK affinity for ATP but decreases it for PL. Li+ is a poor activator which seems to modify the enzymatic mechanism from a random to an ordered sequential pattern with ATP bound before PL. Results suggest that K+ and Na+ bind to PK on the same site while Li+ binds on another site. This hypothesis and the mechanism of monovalent cation-PK interaction are compared to other well-known K(+)-activated enzymes.     

PAC-Membrane Filtration Process.?II: Model Application

The models developed in the first part of this study are applied to predict the removal of 4-nitrophenol by powdered activated carbon (PAC) in a bench-scale reactor. A series of continuous-flow filtration experiments were conducted with different carbon doses to verify the modeling approach when the activated carbon was added directly to the membrane reactor, either as step or pulse input, and when the carbon was dosed as a step input to a continuous-flow stirred tank reactor followed by the membrane reactor. The models predicted well the experimental data for all cases investigated. The verified model was used to investigate the effect of various operating parameters on the efficiency of the adsorption process. This analysis included the effect of filtration time, membrane reactor volume, dosing procedure, and the effect of dosing the carbon in reactors installed in series upstream of the membrane reactor.     

DNA Extraction from Olive Oil and PCR Amplification of Microsatellite Markers

ABSTRACT: DNA was extracted from single-cultivar of cold-pressed (virgin) unfiltered and cotton-filtered olive oils that were stored at 4 °C for up to a year using different DNA extraction kits and protocols. DNA was amplified using original and nested primers designed on 6 microsatellites loci of the UDO series. The most consistent results in terms of successful single sequence repeat amplifications were achieved using the Qiagen QIAamp DNA stool extraction kit, slightly modified and applied to oil sample amounts as small as 200 μL without any pretreatment. The kit allowed getting polymerase chain reaction (PCR) amplicons visible on gel and scorable peaks at the automatic sequencer for all 6 markers analyzed. Less consistent results were achieved with other kits, such as the Promega Wizard Magnetic DNA Purification System for Food, the LB Link-Biotech ExtMan 50–100 Evolution, the Qiagen Plant Mini kit, and the standard cetyltrimethyl-ammonium bromide-based DNA extraction protocol. The integration in the protocols of further tools, such as the hexane-based phase separation, the addition of water or NaCl solutions to the oil, the precipitation and the use of the pellet, and others, did not result in any substantial use. PCR amplifications that gave low DNA yields were improved by adopting the nested PCR technique, which uses the product of the 1st PCR as a template for a 2nd PCR carried out by means of internal primers. Conclusions are drawn as to the applicability of the method to trace the identity of single-cultivar virgin olive oils. Further work is required to check the sensitivity of the method in determining the varietal composition of blended oils, especially in detecting alleles from cultivars present in only small amounts.