Fat mimicking compounds as grease thickeners in Poly(ethylene glycol)/water: Adopting the solution from history.

Water-based lubricants are thought to be the next generation green lubricants, however, there are very few developments of aqueous grease lubricants. Here, water-based grease lubricants were developed using the food fat replacers. The concept of using fat replacers was inspired by the historical usage of fat as a lubricant. Dextrins were chosen as the fat replacers and mixture of water and PEG as the base fluid. Dextrins with different molecular weights were selected to study its effect on the rheological, tribological and thermal behavior of the gels. It was found that only higher molecular weight dextrins will form the colloidal gels, whereas low molecular weight dextrins will form the colloidal solution. The SEM images of the dried samples showed the agglomerated micro-spherical network with the void to hold the base fluid. It was found that, at an optimum concentration, the fat replacers showed 35-58% lower friction and 29-41% lower wear than the pure PEG200/water solution regardless of their molecular weight. The spherical shaped colloidal particles will form the film over the metal surface by nano-filling and these particles will act as nano-bearings which will reduce the wear and friction. These gel lubricants can be used where the highly biodegradable and bio-compatible green lubricant is needed.

Polyelectrolyte cellulose gel with PEG/water: Toward fully green lubricating grease.

Developing a fully green lubricant is an urgent need due to the growing consciousness of environmental protection and dwindling resources. In this work, fully green gel lubricants were developed out of cellulose derivatives as gelator and mixture of water and poly(ethylene glycol) 200 (PEG 200) as the base fluid. The non-ionic hydroxyethyl cellulose (HEC) and anionic sodium carboxymethyl cellulose (NaCMC) were chosen to understand the effect of ionic and non-ionic gelators on the thermal, rheological and the tribological properties of the gel lubricant. HEC or NaCMC is demonstrated as effective additive to reduce wear, stabilize friction coefficient and enhance the thermal stability of developed lubricants. It is shown that anionic gelator will result in producing lower friction and wear in comparison to non-ionic gelator, which may be attributed to the possible tribo-film formation due to the negative charge in the NaCMC molecules and its larger molecular weight.

Comparative Evaluation of Nemoceph and Foxit PDF Reader for Steiner's Cephalometric Analysis.

AIM: The aim of this study was to evaluate and compare the values of Steiner's cephalometric analysis using Nemoceph and Foxit PDF Reader. No significant difference between the two methods will result in that Foxit PDF Reader can be used as a cost-effective alternative. MATERIALS AND METHODS: This study was conducted on 100 digital lateral cephalograms taken from the same machine. The samples were collected by nonprobability convenience sampling procedures. These images were analyzed for Steiner's cephalometric analysis using two software packages. RESULTS: The skeletal and dental values showed no statistically significant difference in the majority, except for the L1-NA (linear) and L1-NB (linear). CONCLUSION: Results showed that there is a high agreement between the two methods. CLINICAL SIGNIFICANCE: This article provides a simple and cost-effective method of onscreen cephalometric analysis. This technique uses the inbuilt measurement tools in the tool bar of our daily use software. The method can be used independently anywhere without any internet connection and software subscription.

Malocclusion in individuals with mental subnormality--a review.

The occurrence of malocclusion in individuals with mental disability poses an additional obstacle to social acceptance; not only from an esthetic point of view, but also in that it compromises all aspects of oral function. This review examines the reported prevalence of malocclusion in individuals with mental subnormality including Down syndrome, from 1981 to 2013, assessed according to Angle's classification, the Dental Aesthetic Index (DAI), the Index of Orthodontic Treatment Need (IOTN) and certain malocclusions. Although widely reported in many studies, it is still quite difficult to compare the exact proportion of occlusal anomalies and orthodontic treatment need among mentally challenged individuals. This is due partly to the multiplicity of measurement methods and the difficulty in standardizing criteria. Several studies have reported higher prevalence of malocclusion including anterior open bite, anterior cross bite, severe malocclusions in mentally challenged individuals, especially those with Down syndrome. The findings have been varied and attributed to musculoskeletal abnormalities, altered cranial-base relationships, premature tooth loss or eruption, lip incompetence, etc. Future research needs to be devoted to determining exactly why malocclusion is higher among individuals with mental subnormalities. It will be a challenge to identify the preventable factors among multiple complex etiologies to reduce these disparities.

Evaluation of friction in orthodontics using various brackets and archwire combinations-an in vitro study.

AIM: The aim of this study was to compare frictional resistance which was produced between conventional brackets (0.022 slot Otho-Organiser) and self ligating brackets (active Forestadent and passive Damon III) by using various arch wire combinations (0.016 Niti, 0.018 Niti, 0.017 x 0.025 SS and 0.019 x 0.025 SS). METHODS: An experimental model which consisted of 5 aligned stainless steel 0.022-in brackets was used to assess frictional forces which were produced by SLBs (self ligating brackets) and CELs (conventional elastomeric ligatures) with use of 0.016 nickel titanium, 0.018 nickel titanium, 0.017 X 0.025"stainless steel and 0.019 X 0.025"stainless steel wires. STATISTICAL ANALYSIS: One way ANOVA test was used to study the effect of the bracket type, wire alloy and section on frictional resistance test . RESULTS: Conventional brackets produced highest levels of friction for all bracket/archwire combinations. Both Damon III and Forestadent brackets were found to produce significantly lower levels of friction when they were compared with elastomerically tied conventional brackets. CONCLUSION: SLBs are valid alternatives for low friction during sliding mechanics.