Corrosive-Abrasive Wear Induced by Soot in Boundary Lubrication Regime

Soot is known to induce high wear in engine components. The mechanism by which soot induces wear is not well understood. Although several mechanisms have been suggested, there is still no consensus. This study aims to investigate the most likely mechanism responsible for soot-induced wear in the boundary lubrication regime. Results from this study have shown that previously suggested mechanisms such as abrasion and additive adsorption do not fully explain the high wear observed when soot is present. Based on the results obtained from tests conducted at varying temperature and soot levels, it has been proven that the corrosive–abrasive mechanism was responsible for high wear that occurred in boundary lubrication conditions

A preliminary evaluation of optometric management and referral protocols for pa-tients with diabetic retinopathy

Aim: The purpose of this pilot study was to investigate  the  assessment,  management  and referral practices of South African optometrists in  the  care  of  patients  with  diabetic  retinop-athy  (DR)  and  to  recommend  strategies  to improve  and  standardize  patient  management as required.  Methods:  The  study  design  incorporated quantitative,  qualitative  and  clinical  measures that were administered to fourteen experienced optometrists from the Durban area. The quan-titative measure, the questionnaire in appendix I, evaluated the optometrists’ management pro-tocols of patients with diabetes mellitus (DM).  These  included  the  optometrists’  referral  and co-management practices, their awareness and usage  of  appropriate  guidelines  in  the  man-agement  and  referral  of  these  patients,  their perceived levels of competence and confidence in their education, levels of service offered to the patients and finally the role of Continuous Professional  Development  (CPD).  This  self-report information was supplemented by a set of clinical measures where the study sample grad-ed levels of DR, chose appropriate management options  and  indicated  prognosis  for  disease progression based on a set of slides presented to  them.  Finally  the  fourteen  optometrists,  as well as two ophthalmologists, were interviewed using tailored, semi-structured interview sched-ules. These interviews were used to elaborate and corroborate information obtained from the other two research approaches.  Results:  Descriptive  analysis  was  used  to analyse  the  data  from  the  quantitative  and clinical  measures,  whilst  the  interviews  were analysed  thematically.  Although  86%  of  the sample routinely screened for ocular manifesta-tions of DM, there was no standardization in the criteria used by the fourteen optometrists. Only  15%  of  the  sample  reportedly  assessed their  patients  using  dilated  fundus  examina-tions  (DFE),  which  is  the  internationally  rec-ommended standard of care. The results of the clinical measures indicated that there was a lack of standardization in the management and refer-ral of patients with DR by the study sample, contrary  to  their  own  levels  of  confidence  in their  educational  competencies  regarding  DR and their perception of the level of service that they  offered  to  their  patients.  The  interviews with the optometrists provided crucial insights into this lack of standardised care of patients with DR, with the ophthalmologists confirming the  urgent  need  for  CPD  aimed  at  enhancing clinical  skills  and  ensuring  standardization  in the  management  and  referral  of  patients  with DR.  This finding was particularly relevant for co-management models.Conclusion: This  pilot  study  indicates  that the  performance  of  the  optometrists  (albeit  a relatively small group) in the assessment, man-agement and referral of patients with DR was inconsistent  and  not  in  keeping  with  interna-tionally recommended guidelines. It is recom-mended  that  CPD  programmes  focus  on  the improvement of clinical skills and on the imple-mentation of existing standardised management protocols  for  patients  with  DR.  This  should result in improved patient care, patient confi-dence and loyalty with regard to care received, efficient and effective models of management and  co-management  and  decreased  costs  to patients and the health care system

The effects of diesel contaminants on tribological performance on sliding steel on steel contacts

This article presents the findings from a parametric study examining the effect of four contaminants (soot, oxidation, moisture, and sulphuric acid) at varying levels (four for each). It was observed that all contaminants and contaminant levels reduce the conductivity of the oil. Oxidation and soot contaminants produced large increases in viscosity. The wear rate was mainly influenced by acid and soot additions, while the coefficient of friction was increased by all contaminants and contaminant levels. The steady-state charge levels changed for some contaminants. The best correlation of steady-state charge with the other measured tribological parameters of wear rate, friction, and temperature is seen for the series of oxidized oils. The multi-contaminated oil (L4?×?4) shows remarkably little degradation in tribological performance. Analysis of the wear mechanisms shows that soot and oxidation produced abrasion and polishing wear, respectively, while sulphuric acid and moisture produced corrosive wear. <br/