Ferrographic analysis of wear particles from sliding elastohydrodynamic experiments

The Ferrograph was used to analyze wear debris generated in a sliding elastohydrodynamic contact. The amount of wear debris correlates well with the ratio of film thickness to composite surface roughness (A ratio). The general wear level parameter and the wear severity index yielded similar correlations with average A ratios. Essentially all the generated wear particles were of the normal rubbing wear type. The Ferrograph was more sensitive in detecting the wear debris than was the commonly used emission spectrograph

Ferrographic analysis of wear debris generated in a sliding elastohydrodynamic contact

The ferrograph was used to analyze wear debris generated in a sliding elastohydrodynamic contact. The amount of wear debris correlates well with the ratio of film thickness to composite surface roughness. Essentially all of the generated wear particles were of the normal rubbing wear type

Breaking an Epigenetic Chromatin Switch: Curious Features of Hysteresis in Saccharomyces cerevisiae Telomeric Silencing

In addition to gene network switches, local epigenetic modifications to DNA and histones play an important role in all-or-none cellular decision-making. Here, we study the dynamical design of a well-characterized epigenetic chromatin switch: the yeast SIR system, in order to understand the origin of the stability of epigenetic states. We study hysteresis in this system by perturbing it with a histone deacetylase inhibitor. We find that SIR silencing has many characteristics of a non-linear bistable system, as observed in conventional genetic switches, which are based on activities of a few promoters affecting each other through the abundance of their gene products. Quite remarkably, our experiments in yeast telomeric silencing show a very distinctive pattern when it comes to the transition from bistability to monostability. In particular, the loss of the stable silenced state, upon increasing the inhibitor concentration, does not seem to show the expected saddle node behavior, instead looking like a supercritical pitchfork bifurcation. In other words, the 'off' state merges with the 'on' state at a threshold concentration leading to a single state, as opposed to the two states remaining distinct up to the threshold and exhibiting a discontinuous jump from the 'off' to the 'on' state. We argue that this is an inevitable consequence of silenced and active regions coexisting with dynamic domain boundaries. The experimental observations in our study therefore have broad implications for the understanding of chromatin silencing in yeast and beyond

Study on Strength and Self-Healing Behaviour of Bio-Concrete

Micro cracks are very commonly observed in concrete structures. Due to increased permeability through these micro cracks, durability of concrete structures reduces by the entry of chemical through these micro pores particularly in moist environments. In the field, crack repair is labour intensive. It is more advisable to restrict the early age small cracks the moment they appear instead of repairing after large cracks formed. In order to increase the durability of concrete against these commonly observed pores in concrete structures, autogenous pore refinement method can be adopted so that monitoring of the structure against these micro pores can be avoided. By using the principle of Biomineralization, Bacteria forms the Calcium precipitations which is usually called microbial induced calcite precipitation (MIC) .In the present work, the bacteria which will grow in the high alkaline media is chosen since concrete is highly alkaline material and cultured in the controlled medium to get the desired concentration of cells. In the present work, Un-identified and Bacillus sphericus bacterial broth is used for the study. It is observed that these bacteria when mixed with concrete at the concentration of 106 cells per ml, the compressive strength is increased by 36.36 % and 13.63 % and for 107 concentrations of cells, the un-identified bacteria show the increase of compressive strength as 29.56 %. Modulus of elasticity of concrete is increased by 23.78 % and 31 % for both bacteria at the concentration of 106 cells per ml of water and Split tensile strength is increased by 23.5 % and 28.5 % for concentration 106 and 107 cells of Bacillus sphericus. SEM and EDAX analysis reveals the deposition of calcium carbonate Keywords: Self-healing, bio mineralization, strengt

A thermo-chemical exploration of a two-dimensional reacting supersonic mixing layer

The hypervelocity two-dimensional reacting supersonic mixing layer experiments of Erdos et al. with a H2/air stream have been simulated with model free fine grid calculations on a N-S solver with full and single step chemistry. Response of the flow to fluctuations in the in-flow stream is utilized to examine chemistry fluid flow interactions. A favourable comparison of the computation with experimentally measured wall static pressure and heat transfer data along with flow picture forms the basis for further analysis. Insight into the mean flow thermal and reaction properties is provided from the examination of large scale structures in the flow in which the hydrogen stream is at 103 K flowing at 2.4 km/s (M = 3.09) and the air stream is at 2400 K flowing at 3.8 km/s (M = 3.99). The chemistry-flow interaction is dominated by large stream kinetic energy and affects the mean properties including the temperature profiles across the mixing layer. Single step chemistry, in comparison to full chemistry, is inadequate to describe ignition and early combustion processes, but seems reasonable for describing mixing and combustion downstream. Fast chemistry approximation coupled with mixture fraction based on hydrogen element seems to predict H2 mean profiles well; but this is shown to be due to the insensitivity of YH2 to progress of the reaction. This approximation under-predicts YO2 though the general shape of the profile is maintained. Mixture fraction variable approach is shown to be inadequate for the prediction of the H2O mass fraction because of the effect of non-normal diffusion. Finite chemistry conditions are shown to prevail throughout the domain of the mixing layer. It appears that use of mixture fraction approach may be inadequate to compute high speed reacting turbulent flows

Prospective clinical study of surgical management of varicose veins of lower limb and its complications

Background: Varicose veins of the lower extremities are the most common peripheral vascular disease and their treatment is as old as mankind. This prospective clinical study of surgical management of varicose vein was conducted to study the age, sex and occupational distribution of varicose veins of lower limb. Evaluations of clinical features and surgical methods of treatments that were in practice in the management of varicose veins in terms of recurrence and symptoms improvement were also studied.Methods: Two years prospective study was conducted in our institution from May 2007 to April 2009. During this period 62 cases of varicose veins of lower limbs were admitted to our hospital of which 50 cases were selected and were studies in detail. After thorough clinical examination and relevant investigation they are all subjected to surgical management. Results: Out of 50 cases studied, 21 (42%) had only long saphenous vein involvement, 7 (14%) had short saphenous vein involvement and in 5 (10%) cases both short and long saphenous system were involved. In addition to long saphenous vein involvement, incompetent perforators were present in 17 (34%) cases. Among them prominent veins and pain were the main complain in 38 (78%) patients. Itching and pigmentation were present in 4 (8%) patients. Ankle edema was present in 6 (12%) patients. Pain and ulceration of lower leg were present in 2 (4%) patients. After clinical assessment appropriate surgical procedures were followed for each of patients. These cases were followed for 3 year durations. Out of 50 patients 7 (14%) patients had recurrence of varicose vein. 7 (14%) patient complained of recurrence of pain after 2 years of surgery but no appearance of varicose vein. One patient (2%) complained of persistence of pigmentation after surgery. 2 (4%) patients complained of persistence of ankle edema and there was complete healing of ulcer which was present earlier. Conclusions: Commonest age group of varicose vein of lower limb was 20 to 40 years. Definite relationship exists between the occupation and the incidence of varicose veins. The patients were in the occupation which required standing for long time had the higher chances of varicose vein. Severity of the symptoms is not proportional to the duration of varicose veins. The involvement of long saphenous vein is more common than the short saphenous vein. Since our study shows very low percentage of recurrence and symptoms related to varicose vein the surgical line of treatment is an ideal treatment for varicose vein. For incompetent perforators, sub-fascial ligation appears to be a better method of treatment than extra fascial ligation. Because in the former all the perforators could be visualized and dealt with, while in the latter there were chances of missing one or two perforators. If cases are selected properly with good operative technique the complications are negligible.

D-Homothetically Deformed K-Contact Ricci almost Solitons

If a K-contact manifold (M, g) and a D-homothetically deformed K-contact manifold (M,g¯)\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$(M,{\bar{g}})$$\end{document} are both Ricci almost solitons with the same associated vector field V, then we show (i) that (M, g) and (M,g¯\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$M, {\bar{g}}$$\end{document}) are both D-homothetically fixed η\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\eta$$\end{document}-Einstein Ricci solitons, and (ii) V preserves \documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\phi$$\end{document}. We also show that, if the associated vector field V of a complete K-contact Ricci almost soliton (M, g, V) is a projective vector field, then V is Killing and (M, g) is compact Sasakian and shrinking. Finally, we show that the divergence of any vector field is invariant under a D-homothetic deformation

Investigations of lubricant rheology as applied to elastohydrodynamic lubrication

Traction prediction in sliding elastohydrodynamic (EHD) contacts was examined along with an elastohydrodynamic lubrication simulation of the effects of load and speed on temperatures in the EHD contact. An existing shear stress theory and lubricant rheological model were studied and evaluated by applying them to traction prediction. Results obtained using measured film thickness and surface temperature data, were compared with measured traction values. The infrared technique for measuring temperatures in an EHD contact was further developed and ball surface and fluid temperatures are reported for sliding speeds of 0.35 to 5.08 m/s at 0.52 to 2.03 GN/sq m maximum pressure and surface roughnesses of .011 to .381 micrometers c.1.a. The relationship between asperity interaction, as measured by relocation surface profilimetry and high frequency temperature measurements, and the ratio of film thickness to surface roughness was also studied

Phthaloyl amlodipine

The title compound [alternatively called 3-ethyl 5-methyl 4-(2-chloro­phenyl)-2-(2-phthalmidoethoxy­methyl)-6-methyl-1,4-di­hydro­pyridine-3,5-di­carboxyl­ate or ethyl methyl (4RS)-4-(2-chloro­phenyl)-2-({[2-(1,3-dioxo-1,3-di­hydro-2H-isoindol-2-yl)­ethyl]­oxy}methyl)-6-methyl-1,4-di­hydro­pyridine-3,5-di­carboxyl­ate], C28H27ClN2O7, is a calcium channel blocker and belongs to the family of anti-anginal and antihypertensive reagents. The di­hydro­pyridine ring adopts an envelope conformation. The molecular conformation is stabilized by an intramolecular N-H...O hydrogen bond

Frontal electroencephalogram based drug, sex, and age independent sedation level prediction using non-linear machine learning algorithms

Brain monitors which track quantitative electroencephalogram (EEG) signatures to monitor sedation levels are drug and patient specific. There is a need for robust sedation level monitoring systems to accurately track sedation levels across all drug classes, sex and age groups. Forty-four quantitative features estimated from a pooled dataset of 204 EEG recordings from 66 healthy adult volunteers who received either propofol, dexmedetomidine, or sevoflurane (all with and without remifentanil) were used in a machine learning based automated system to estimate the depth of sedation. Model training and evaluation were performed using leave-one-out cross validation methodology. We trained four machine learning models to predict sedation levels and evaluated the influence of remifentanil, age, and sex on the prediction performance. The area under the receiver-operator characteristic curve (AUC) was used to assess the performance of the prediction model. The ensemble tree with bagging outperformed other machine learning models and predicted sedation levels with an AUC = 0.88 (0.81-0.90). There were significant differences in the prediction probability of the automated systems when trained and tested across different age groups and sex. The performance of the EEG based sedation level prediction system is drug, sex, and age specific. Nonlinear machine-learning models using quantitative EEG features can accurately predict sedation levels. The results obtained in this study may provide a useful reference for developing next generation EEG based sedation level prediction systems using advanced machine learning algorithms