Gas—Liquid Mass Transfer Coefficient in Stirred Tank Reactors

Volumetric gas—liquid mass transfer coefficient (k_La) data available in the literature for larger tanks (T = 0.39 m to 2.7 m) have been analyzed on the basis of relative dispersion parameter, N/N_cd. It was observed that at a given superficial gas velocity (V_G), k_La values were approximately the same irrespective of geometric configuration (size of the tank, type and size of the impellers, type of the sparger, etc.) at a particular N/N_cd. A single correlation based on N/N_cd is presented which shows satisfactory agreement with the k_La data of different workers.     

Gas Hold‐Up in Stirred Tank Reactors in the Presence of Inorganic Electrolytes

Gas hold‐up (?_G) in air‐aqueous electrolyte solutions in stirred tank reactors (STR) is correlated using a relative gas dispersion parameter, N/N_cd and a surface tension factor (STF), (c/z)(dδ/dc)². For electrolyte concentration below transition concentration (c_t) a single correlation in the form of ?_G = f(N/N_cd, vvm, STF) shows good agreement with gas hold‐up data over a wide range of system and operating conditions. Above ct no effect of STF on gas hold‐up is observed and the correlation obtained is of the form ?_G = f(N/N_cd, vvm). Data available in the literature on large STR show good fit with the proposed correlation.     

Trust management for e-transactions

There has been enormous increase in transactions and cooperative-computing services on the internet. This is both a technical and a social phenomenon. Transactions and services over the internet have global reach and users, known or unknown to the service provider, might be interested in availing access or participating in the cooperative transaction in a distributed manner. Thus, it is very important for service providers to identify and establish trustworthiness of potential collaborators, which they do by writing contracts (e.g. access control, security policies; the words contract and policy are used interchangeably) without violating the privacy and confidentiality laws that prevail across geographical boundaries. But as the system becomes complex and dynamic, contractual incompleteness arises since it becomes cumbersome to mention potentially large set of outcomes of the user's choice of action. Trust plays a crucial role in the design of optimal contracts; not all the relevant, valuable information on the user's choice of action is incorporated in the equilibrium contract. It may also be noted in that traditional transactions, the notion ofseeing is believing plays a vital role. However, in e-transactions, this is not the case. The challenge is to see how in such a scenario trust can indeed be generated. Note that the presence of trust facilitates cooperative behaviour and allows for exchange to occur in situations where its absence would preclude trade. In this paper, we shall present a comparative analysis of various approaches of trust management in practice that integrates technology with other factors. We shall also bring out the relative deficiencies and how these issues are tackled in our ongoing work that facilitates execution of optimal contracts.     

Extraction of fibers from saccharum munja grass and its application in composites

With growing environmental awareness, ecological concerns and new legislations, natural fiber‐reinforced plastic composites have received increasing attention during the recent decades. The natural fiber composites have many advantages over traditional glass fiber composites, including lower cost, lighter weight, environmental friendliness, and recyclability. This article reports the findings of the studies done on a new fiber, hitherto unexplored, extracted from Saccharum munja grass. The extracted fibers were further treated using sodium hydroxide to improve its performance in composites. Both treated and untreated fiber‐reinforced composites were prepared by hand lay‐up process using unsaturated polyester resin. Mechanical properties and thermal behavior of the composites were evaluated. The improvement in properties was found for alkali‐treated fiber composites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40829.     

Photocatalytic degradation of 4-nitroaniline using solar and artificial UV radiation

The photocatalytic degradation (PCD) of 4-nitroaniline was studied in the presence of TiO₂ suspensions in a batch and continuous annular reactor. Artificial and solar radiation was employed as sources of UV radiation. The effect of catalyst loading, pH, presence of anions and initial concentration on the rate of photocatalytic degradation was investigated. p-Aminophenol, p-benzoquinone and hydroquinone were identified as the intermediates during the degradation process. A kinetic expression for PCD of 4-NA is provided.     

Building Bridges and Breaking Barriers… the Story Continues

Last time I wrote in this column was May 2005, when I talked about breaking the workflow barriers between the thermal specialist and process engineer and building a bridge of integration between software for simulation and design of heat transfer equipment and process simulation software. Referring to the cover page picture, this essentially represents the iterative workings between the process flowsheet where exchanger duty is specified and thermal design, or simulation, of the exchanger.

Now I want to share how this process of bridge building continues down the workflow toward the final stage of exchanger fabrication. The relevant bridge, this time, is between thermal design and mechanical design of the exchanger.     

The use of personality measures in cross-cultural research: A test of three personality scales across two countries.

This study explored the measurement equivalence of 3 commonly used psychological measures across samples of U.S. and Indian male and female respondents. Multiple groups structural equations modeling indicated that locus of control was measured equivalently across U.S. and Indian male and female groups, whereas measurement equivalence of a self-esteem scale and a higher order need strength scale was observed across U.S. men, U.S. women, and Indian men. Baseline models for self-esteem and for higher order need strength failed to fit in the Indian female sample, suggesting basic differences in how respondents from this group conceptualized scale items. The results underscore the potential importance of culture as a factor that may moderate the types of inferences that can be made from test scores in cross-cultural research applications. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

AJAX风格的Web开发

在过去几个月期间，结合了Asynchronous JavaScript和XML（AJAX）来开发高交互性Web应用程序的设计模式变得越来越流行。高配置的Web应用程序，如Google Maps和A9以及微软的Virtual Earth和Start．com，通常能够利用这些技术的组合来形成丰富的客户端用户体验。组成AJAX的单项技术并不是最新的开发工具——它们已经运用了一段时间，并且不断得到更新和改进。但是，它汇聚了最新的技术，从而导致各种引人注目的可能性。     

Detoxification of a carcinogenic paint preservative by Blumea malcolmii Hook cell cultures

Phytoremediation is considered as an effective viable alternative to remediate the contaminated sites, industrially hazardous chemicals and other toxic pollutants. This bioremediation option offers a safe, cheap and eco friendly alternative to existing physical and chemical remediation technologies as well as other biological sources. The wall paint preservatives consist of several harmful and carcinogenic compounds causing serious environmental concerns. In the present study, an actively growing Blumea malcolmii Hook cell suspensions were established successfully on MS+CM (20%) +2,4-D (5 mg l(-1))+Gln (100 mg l(-1))+sucrose (3%) and were used to detoxify a paint preservative Troysan S 89 (a mixture of carbendazim, diuron and ochthilinone). FTIR and UV spectral analytical studies revealed the phytotransformation of Troysan S 89 by Blumea cell suspension cultures. The non-toxic nature of the products formed after phytotransformation was confirmed by phytotoxicity, cytogenotoxicity while non-carcinogenic nature by Ames tests. The novelty of the present study is effective communal degradation of a mixture of three toxicants in Troysan S 89 by cell suspension cultures of Blumea. This work suggested that Blumea cell suspensions might be able to contribute to the wider and safer application of phytoremediation.     

Harvesting of Saccharomyces cerevisiae using colloidal gas aphrons

Adsorptive bubble separation using Colloidal Gas Aphrons (CGA) can be used for harvesting of microorganisms. The effect of various operating parameters, for example pH, biomass loading, dispersed and continuous phase velocity, surfactant type and concentration, has been studied on the recovery of Saccharomyces cerevisiae. The operating conditions were optimised for maximum separation. The results obtained have been compared with the prediction of an model earlier.