Effect of sintering and coldbonding techniques onlightweight aggregates fromindustrial waste – a review

Concrete is a building material which consist major portion of hard inorganic materials called aggregates such as crushed stone aggregate. Due to continuous usage of natural resources within a short length of time these get depleted. Production of concreteby using waste materials from industries is important in this era. The production of light weight aggregate from waste material is done by pellatization and hardened by sintering or cold bonding techniques. Depending upon the hardening methods the properties of concrete is also varied. From previous research works it can be concluded that it is possible to produce structural concrete using sintered fly ash aggregate which are spherical in shape having specific gravity varying from 1.33 to 2.35. According to the literature, the specific gravity of these aggregates was 16 to 46 percent lower than that of standard of weight aggregates, and they might be employed as aggregates in structural concrete production depending on the constituent qualities and the production environment. Cold bonded aggregate concretewith compressive strength 48% lesser compared to normal concrete mix, it exceeds the value of 17 MPa that has been fixed as minimum criteria for concrete to be used as a structural material. This paper mainly focuses on review of artificial light weight aggregate from cold bonding and sintering methods and how these methods affect the concrete properties. From different studies, it is concluded that Cold bonding is an energy saving method and Sintered sludge pellets have a stronger aggregate strength, larger porosity, and lower aggregate density than cold bonded aggregates, exhibiting qualities that are superior to those required of building aggregates. Sustainable development is indeed achievable in this developing era and lightweight aggregate in construction sector is key to achieve this

Inducible Protective Processes in Animal Systems .5. Clastogenic Adaptation Triggered by Low-Dose of Methyl Methanesulfonate (Mms) in Poecilocerus-Pictus

The monofunctional alkylating agent methyl methanesulfonate (MMS) was used to study the induction of inducible protective processes (clastogenic adaptation) in meiotic cells of the grasshopper, Poecilocerus pictus. After a low (conditioning) dose of 0.012 M and challenging with a high (challenging) dose of 0.048 M MMS after 2 h time-lag, the incidence of chromosomal anomalies in metaphase I, II and anaphase I and II stages was found to be significantly less (P < 0.05) compared to that of the additive effect of both the conditioning and the challenging doses. The data suggest that the low dose of MMS rendered the meiotic cells more resistant to the clastogenic effects of a subsequent high dose of MMS employed. These results lend further support to the earlier report from the same laboratory where a low dose of ethyl methanesulfonate (EMS) was found to render protection against a high dose of the same clastogen in meiotic cells of P. pictus. Furthermore, it is clear from the results that conditioning by the methylating (MMS) agent in cells is less effective in comparison with that of the ethylating (EMS) agent

A review on the effects of artificial light weight aggregate in concrete

The disposal problem of industrial by-products like fly ash, heavy metal sludge, sewage sludge etc. are increasing day by day. To use by-products in large volume the applications like embankment fill or aggregate replacement material should be considered for sustainable development. This study is focused on properties of artificial light weight aggregate on concrete and the effect of cold bonded light weight aggregate on concrete through partial and complete replacement of coarse aggregates. Artificial Lightweight aggregate can be produced by nodulizing the by-product for example fly ash in a pelletizer with a proportionate quantity of water, cement and further hardened by cold bonding or sintering. Due to the impact of earth quake forces all over the world, the need for light weight structural design is increasing presently, as it reduces mass of the structure. The concrete produced is light weight in nature and has added the benefit of reducing overall cost, especially in transportation and placing etc. it has its own advantages like reduced dead load, and thus economic structures, high sound absorption and good fire resistance. Keywords—Artificial light weight aggregate, cold bonding, Fly ash, Fly ash aggregate, Pelletization, and Sintering

Home Ownership, Savings, and Mobility Over The Life Cycle

In a Bewley model with endogenous price volatility, home ownership and mobility across locations and jobs, we assess the contribution of financial constraints, housing illiquidities and house price risk to home ownership over the life cycle. The model can explain the rise in home ownership and fall in mobility over the life cycle. While some households rent due to borrowing constraints in the mortgage market, factors that effect propensities to save and move, such as risky house values and transactions costs, are more important determinants of the ownership rate

Impact of chromophores on colour appearance in a computational skin model

Early diagnosis of skin cancer offers the patient more favorable treatment options. Color fidelity of skin images is a major concern for dermatologists as adoption of digital dermatoscopes is increasing rapidly. Accurate color depiction of the lesion and surrounding skin are vital in diagnostic evaluation of a lesion. We previously introduced VCT-Derma, a pipeline for dermatological Virtual Clinical Trials (VCTs) including detailed and flexible models of human skin and lesions, which represent the patient in the entire dermatoscopy-based diagnostic process. However, those initial models of skin and lesions did not properly account for tissue colors. Our new skin model accounts for tissue color appearance by incorporating chromophores (e.g., melanin, blood) into the tissue model, and simulating the optical properties of the various skin layers. The physical properties of the skin and lesion were selected from clinically plausible values. The model and simulated dermatoscope images were created in open modelling software, assuming a linear camera model. We have assumed ambient white lighting, with a 6mm distance to the camera. Our model of color appearance was characterised by comparing the brightness of the lesion to its depth. The brightness of the lesion is compared through the variability of the mean gray values of a cropped region around the lesion. We compare two skin models, one without extensive chromophore content and one with. Our preliminary evaluation of increasing chromophore content shows promise based on the results presented here. Further refinement and validation of the model is ongoing

A Modular and Integrated Optimisation Model for Underwater Vehicles

A modular and integrated optimisation model for the design of underwater vehicles is presented. In the proposed optimisation model two modules (i.e. low fidelity and high fidelity) are incorporated and the basic geometric definition of computer aided design (CAD) is integrated with computational fluid dynamic (CFD) analysis. The hydrodynamic drag is considered as single objective with constraints on the geometric parameters of dimension, space and volume. The CAD model is implemented in MATLAB*TM and CFD model is implemented in Shipflow**TM. A real-world design example of an existing underwater vehicles is presented. The applicability of proposed optimisation model is shown. The presented results show that within given set or sets of constraints the application of optimisation model in design results into an efficient hull form.

Plasma-Enhanced Chemical Vapor Deposition: Where we are and the Outlook for the Future

Chemical vapor deposition (CVD) is a technique for the fabrication of thin films of polymeric materials, which has successfully overcome some of the issues faced by wet chemical fabrication and other deposition methods. There are many hybrid techniques, which arise from CVD and are constantly evolving in order to modify the properties of the fabricated thin films. Amongst them, plasma enhanced chemical vapor deposition (PECVD) is a technique that can extend the applicability of the method for various precursors, reactive organic and inorganic materials as well as inert materials. Organic/inorganic monomers, which are used as precursors in the PECVD technique, undergo disintegration and radical polymerization while exposed to a high-energy plasma stream, followed by thin film deposition. In this chapter, we have provided a summary of the history, various characteristics as well as the main applications of PECVD. By demonstrating the advantages and disadvantages of PECVD, we have provided a comparison of this technique with other techniques. PECVD, like any other techniques, still suffers from some restrictions, such as selection of appropriate monomers, or suitable inlet instrument. However, the remarkable properties of this technique and variety of possible applications make it an area of interest for researchers, and offers potential for many future developments

Validation of the modified Berlin questionnaire to identify patients at risk for the obstructive sleep apnoea syndrome

Background &amp; Objectives: Awareness regarding obstructive sleep apnoea (OSA) among general public as well as practicing physicians is low in India. The present study was undertaken to test the utility of modified Berlin questionnaire for risk categorization of OSA in Indian setting. Methods: The modified Berlin questionnaire was administered in 180 middle aged adults (of 320 screened), of whom, 104 underwent overnight polysomnograhy, in a cross-sectional study at a tertiary care, referral center in north India. Questionnaire addressed the presence of frequency of snoring, wake time sleepiness, fatigue, obesity and hypertension. Subjects with persistent and frequent symptoms in any two of these three domains were considered in high risk category for obstructive sleep apnoea. Overnight polysomnograhy was performed to measure apnoea and hypopnoea index (AHI). Results: Questions about the symptoms demonstrated internal consistency (Cronbach alpha correlations 0.92-0.96). Of the 180 respondents to the screening questions, 80 were in the high risk and the rest were in low risk group. For 104 subjects who underwent polysomnograhy, risk grouping was useful in prediction of AHI. High risk category predicted an AHI &#62; 5 with a sensitivity of 86 per cent, specificity of 95 per cent, positive and negative predictive values of 96 and 82 per cent respectively. These results were comparable to Berlin questionnaire study done in the western population for validation. Interpretation &amp; Conclusion: On the basis of the findings of present study it is concluded that administration of modified Berlin questionnaire prior to a polysomnography study can identify high risk subjects and can thus avoid unnecessary polysomnography studies especially in resource-limited settings. To identify subjects at risk for OSA syndrome in general population, this questionnaire can be applied. However, the findings of the present study need to be confirmed further in a large number of subjects in a community-based setting

Adaptive response to low dose of EMS or MMS in human peripheral blood lymphocytes

Human peripheral blood lymphocytes stimulated in vitro for 6 hr were exposed to a low (conditioning) dose of ethyl methanesulfonate (EMS; 1.5 x 10(-4) M) or methyl methanesulfonate (MMS; 1.5 x 10(-5) M). After 6 hr, the cells were treated with a high (challenging) concentration of the same agent (1.5 x 10(-3) M EMS or 1.5 x 10(-4) M MMS). The cells that received both conditioning and challenging doses became less sensitive to the induction of sister chromatid exchanges (SCEs) than those which did not receive the pretreatment with EMS or MMS. They responded with lower frequencies of SCEs. This suggests that conditioning dose of EMS or MMS has offered the lymphocytes to have decreased SCEs. This led to the realization that pre-exposure of lymphocytes to low dose can cause the induction of repair activity. This is a clear indication of the existence of adaptive response induced by alkylating agents whether it is ethylating or methylating in human lymphocytes in vitro