REACTIVE EXTRACTION OF LEVULINIC ACID FROM AQUEOUS SOLUTIONS WITH TRI-n-OCTYLAMINE (TOA) IN 1-OCTANOL: EQUILIBRIA,KINETICS, AND MODEL DEVELOPMENT

Levulinic acid, a carboxylic acid containing a ketone structure, can be used as an acidulant in foods and beverages. Reactive extraction is a promising alternative for the recovery of carboxylic acids from aqueous streams. The design of an amine extraction process requires kinetic data for the acid-amine + solvent system used. In this study, equilibrium and kinetic data on the extraction of levulinic acid from aqueous solutions using tri-n-octylamine (TOA) in 1-octanol have been determined. The mass transfer coefficients of levulinic acid, TOA, and 2:1 levulinic acid-amine complex in 1-octanol were calculated from the acetic acid mass transfer coefficient, which was determined by measuring its fluxes of simple diffusion from kerosene to water. Based on the Hatta number and the criterion given by Doraiswamy and Sharma, the reaction regime has been found to be instantaneous reaction regime occurring at the interface on the organic phase side. An extraction model comprising equilibrium complexation constant w.r.t 2:1 levulinic acid-TOA complex formation, K_E2i (14.794 (m³ kmol^?1)²), and complex mass transfer coefficient, k_B2A (2.193 × 10^?6 m s^?1), has been developed.     

Stress oscillations in plane stress modelling of flexure—a field-consistency interpretation

Exactly integrated isoparametric plane stress elements behave poorly in flexure. The 4-noded element ‘locks’, with errors that progress indefinitely as element aspect ratio increases. Reduced integration of the shear strain energy eliminates this locking entirely. The 8-noded element does not lock, but improves in performance with reduced integration of shear strain energy. Both elements, with their original shape functions, show severe shear stress oscillations in flexure. In this paper we attribute these oscillations to the lack of ‘consistency’ of shear strain fields derived directly from independent field-variable interpolations. We derive error models for specific tractable examples which can confirm the accuracy of this conceptual scheme through digital computation using the finite element models. A field-consistent redistribution strategy for the shear strain field is offered as an elegant procedure to free the elements of spurious oscillations and give a ‘lock’-free performance.     

Going much beyond the Durfee square: enhancing the <Emphasis Type="Italic">h</Emphasis><Subscript>T</Subscript> index

The objective of this research is to develop a new patent bibliometric performance measure by using modified citation rate analyses with dynamic backward citation windows. Cited half-life employed in bibliometrics was adopted in order to establish a model of annual patent backward citation windows. Based on the dynamic behavior of backward citation windows, the annual backward patent citation rates for each technology domain can be calculated to measure its bibliometric performance. It was found that the dynamic backward citation window represents more accurately the citation cycle time which is a key factor on technology assessment. Because different technology domain may have disparate attributes, a normalized backward citation rate was developed to measure the corresponding rank for each domain respect to the entire industry. Three technology domains were then chosen for demonstrative case studies which represent semiconductor, LCD, and drug industries.     

Carbon Nanotubes and Nanohorn Hybrid Composite Buckypaper as Microporous Layer for Proton Exchange Membrane Fuel Cell

In the present work, carbon nanotubes (CNT) and CNT‐carbon nanohorns (CNH) (0, 30, 50, 70 and 100 wt.% CNH) composite Buckypapers (BPs) were fabricated using vacuum filtration technique. Structure and property relation of composite BPs were studied using scanning electron microscope, four probe technique, BET surface area and contact angle measurements. Properties such as electrical conductivity, hydrophobic nature and microstructure of CNT‐30 wt.% CNH composite BP are superior to other composite BP. Hence, CNT‐30 wt.% CNH composite BP is chosen as a microporous layer (MPL) for PEMFCs and tested in fuel cell testing fixture. Polarization studies reveal that the cells performance with composite BPs is comparable with SGL‐MPL based cell. Hydrogen pumping and polarization studies of the cells confirms that composite BPs act as a good MPL at anode as well as cathode at 0.4 to 0.8 V. Hence, CNT‐CNH composite BPs are potential candidates for PEMFC applications.     

A three-dimensional bibliometric evaluation of recent research in India

In this paper a three-dimensional framework to see how Indian universities and research-focused institutions fare in the world of high end research in terms of excellence and diversity of its research base is proposed. At the country level scholarly performance is broken down into three components—size, excellence and balance or evenness. A web application available in the public domain which visualizes scientific excellence worldwide in several subject areas is used. India has a presence in fifteen of twenty-two subject areas in which there are at least 50 institutes globally that have published more than 500 papers. It has no institution which can be counted at this level of size and excellence in seven areas: Arts and Humanities; Business, Management and Accounting; Health Professions; Neuroscience; Nursing; Psychology; and Social Sciences. India’s research base is completely skewed towards the Physical Sciences and Engineering with very little for Biological Sciences and Medicine and virtually none in Social Sciences and Arts and Humanities when excellence at the highest level is considered. Its performance is also benchmarked against three nations, namely Australia, The Netherlands and Taiwan which are of similar size in terms of GDP and scientific output. It is seen that although India has the highest GDP among the four countries, its performance lags considerably behind. Even in terms of diversity, its performance is poor compared to the three comparator countries.     

Scientific wealth and inequality within nations

We show that the greater the scientific wealth of a nation, the more likely that it will tend to concentrate this excellence in a few premier institutions. That is, great wealth implies great inequality of distribution. The “scientific wealth” is interpreted in terms of citation data harvested by Google Scholar Citations for profiled institutions from all countries in the world.     

Homogenization for Dispersion and Reduction in Length of Carbon Nanotubes

An important aspect that limits the use of carbon nanotubes (CNTs) is the difficulty in obtaining homogeneously dispersed CNTs of uniform length. Hence, homogenization of multi-walled carbon nanotubes (MWCNTs) and single-walled carbon nanotubes (SWCNTs) was carried out using bullet blender and the dispersion behavior was compared with that of ultrasonication. 1% sodium dodecyl sulphate (SDS), Triton-x-100 and polyethylene glycol 4000 were used as dispersing agents during homogenization. The dispersed CNTs were studied using transmission electron microscopy, ImageJ and Raman spectroscopy. Though dispersion and reduction in length of MWCNTs were observed both with ultrasonication and homogenization, lowest length range with about 75% reduction in polydispersity index was obtained on homogenization. Longer time of ultrasonication resulted in damage to small MWCNTs. Well dispersed and shorter MWCNTs were obtained with Triton-x-100 while reduction in length was minimum with SDS. SWCNTs of less than 1 μm length could be obtained by homogenization with Triton-x-100.     

Neonatal benign sacrococcygeal teratoma with N-type rectobulbar fistula

A unique case of benign sacrococcygeal teratoma associated with an N-type rectobulbar fistula is reported.