Chemical Engineering

Investigation of Shelf Life of Potency and Activity of the Lactobacilli Produced Bacteriocins Through Their Exposure to Various Physicochemical Stress Factors

by Myrto-Panagiota Zacharof

published in Probiotics and Antimicrobial Proteins
2012, DOI: 10.1007/s12602-012-9102-2 by Springer

Three Lactobacilli strains, Lactobacillus casei NCIMB 11970, Lactobacillus plantarum NCIMB 8014, Lactobacillus lactis... more Three Lactobacilli strains, Lactobacillus casei NCIMB 11970, Lactobacillus plantarum NCIMB 8014, Lactobacillus lactis NCIMB 8586 have been used for the production of bacteriocins. Though, their production phase, their biochemical nature, their mode of activity even their genetic structure have been widely investigated, there are hardly any studies investigating their potency and activity in depth of time, in other words their shelf life under several physicochemical conditions that may occur during their production in large scale. As such, the effect of several factors influencing the activity and the potency of bacteriocins when produced in large scale was examined as due to bacteriocins peptide nature degradation or denaturation might occur, under extreme physicochemical conditions. During scale-up process, differences between the output data may occur, such as concerning biomass, metabolic by-products and limiting substrate concentrations. These may affect negatively the activity and the potency of the bacteriocins. For investigating these effects and minimizing them, numerous studies were conducted, which were related to the exact phase of the production of these substances, the effect of dilution and temperature changes. These studies could be used in order to minimize the scaling-up effect when decided to produce these peptides in large scale.

Heavy metals and trace elements in atmospheric fall-out: Their relationship with topsoil and wheat element composition

by Gonzalo Bermudez

Journal of Hazardous Materials, In press (Available online 16 February 2012)

The objectives of this study were to determine the average concentrations and deposition rates of 28 elements in... more The objectives of this study were to determine the average concentrations and deposition rates of 28 elements in atmospheric bulk deposition and to elucidate associations among topsoil, bulk deposition and wheat element composition. The fluxes of arsenic (As), copper (Cu), lead (Pb) and zinc (Zn) deposition in Córdoba were higher than in other agro-ecosystems, which reflects both natural (geochemistry and topsoil removal) and anthropogenic sources. High lanthanide, uranium (U) and thorium (Th) concentrations revealed the impact of an open cast uranium mine. The highest enrichment factors (EF) were those of Cu, Pb, Zn and nickel (Ni), with calcium (Ca) being the most prominent in the surroundings of a cement plant. Industries and the transport of airborne urban pollutants were the main anthropogenic sources for Ca, Cu, Ni, Pb, Zn, cadmium (Cd), iron (Fe), manganese (Mn) and antimony (Sb). The concentrations of metals in wheat grain were predicted using the topsoil and atmospheric fall-out composition with R2 = 0.90, with the latter being the best explanatory variable. The present study highlights the potential health hazards of wheat consumption (Environmental Protection Agency) by the assessment of heavy metals in bulk atmospheric deposition.

Experimental Study of Local Axial Mixing in a Pilot-Scale Cold Burner

by Vasile Lavric

Self-sustained supercritical water oxidation process for organic pollutant removal. Part I: Heat integration and energetic sufficiency through supercritical steam turbine

by Vasile Lavric

Self-sustained supercritical water oxidation process for organic pollutant removal. Part II: Eenergetic sufficiency through closed thermodynamic cycles

by Vasile Lavric

Synthesis of A356 Al-high-Ca fly ash composites by pressure infiltration technique and their characterization

by Charalampos Vasilatos

Grigorios Itskos, Pradeep K. Rohatg, Angeliki Moutsatsou John D. DeFouw Nikolaos Koukouzas, Charalampos Vasilatos and Benjamin F. Schultz. in Journal of Material Science. 2012. DOI 10.1007/s10853-012-6258-9

In this study, eight types of A356 Al-fly ash composites have been produced using pressure infiltration technique, by... more In this study, eight types of A356 Al-fly ash composites have been produced using pressure infiltration technique, by utilizing high-Ca lignite fly ash. Such type of ash was for the first time used in Al-composites synthesis, and particularly by liquid metal infiltration techniques. After examining their mineralogy and chemistry, specific, narrow ash size fractions were used for the synthesis of composites, and their certain properties were linked to the microstructure and wear strengths of the produced materials. The effect of using ground ash particles on the uniform microstructure and tribological performance of composites was also investigated. It was concluded that using fine, high-Ca ash particles can advantage the properties of composites, and that using ash particles in a ground form can facilitate the production process of MMCs.

Keywords: Metal-Matrix Composites (MMCs); Particulates; Microstructure; Scanning Electron Microscopy; Fly ash; Wear

Production of hydrogen and light hydrocarbons as a potential gaseous fuel from microwave-heated pyrolysis of waste automotive engine oil

by Su Shiung Lam

Published in International Journal of Hydrogen Energy, DOI: 10.1016/j.ijhydene.2011.12.016 (Article In Press).

Waste automotive engine oil was pyrolyzed in a continuous stirred bed reactor using microwave energy as the heat... more Waste automotive engine oil was pyrolyzed in a continuous stirred bed reactor using microwave energy as the heat source; the yield and characteristics of the incondensable gaseous products are discussed. The recovered gases (41 wt% yield) were found to contain substantial concentrations of light aliphatic hydrocarbons (up to 86 vol.%) that could potentially be used as a chemical feedstock or a fuel source to power the process, or to be reformed to produce hydrogen for use as a second-generation fuel. Examination of the composition of the gases also showed the formation of H2 (up to 19 vol.%) and CO that could also be used as a valuable syngas (with a H2 + CO content of up to 35 vol.%). The high yield of gaseous hydrocarbons can be attributed to the unique heating mode and chemical environment present during microwave-heated pyrolysis. The use of a microwave-heated bed of particulate-carbon showed advantages in transforming waste oil into valuable gases. Hence an environmentally unfriendly waste material can be transformed into a useful resource and serves as an alternative source of hydrogen or hydrocarbon energy. The recovery of valuable gases shows advantage over traditional destructive approaches and suggests excellent potential for recycling problematic waste oil.

Ion beam oxidation of GaAs: The role of ion energy

by Nicole Herbots

O. Vancauwenberghe, N. Herbots. H. Manoharan,a) and M. Ahrens

Massachusetts Institute of Technology, Cambridge,
Maassachusetts 02139

J. Vac. Sci. Technot A 9 (3), May/Jun 1991, pp. 1035-1039

In this work, room temperature oxidation of GaAs was investigated using ion beam oxidation (mO). In lBO, an ion beam... more In this work, room temperature oxidation of GaAs was investigated using ion beam oxidation (mO). In lBO, an ion beam is used to introduce oxygen athermally into the substrate, in this case GaAs. GaAs bonds are broken upon collision with the ions, making gallium and arsenic atoms readily available to react with the oxygen species. Ion beam oxidation of GaAs at room temperature was studied as a function ofoxygen ion energy between 500 and is keY. The ion beam oxidized GaAs was characterized in situ by Auger electron spectroscopy (AES) and ex situ with x-ray photoelectron spectroscopy (XPS) for accurate determination of the film chemical composition. Below 1 keY, a thin oxide film is formed: it is composed of Ga20 3 and AS20 3 with almost no metallic arsenic, and presents insulating properties.
As the ion energy increases, preferential sputtering of As and decomposition of AS203 increase and prevent formation of an
insulating film. No damage was detected by Rutherford backscattering spectrometry (RES) combined with ion channeling, in the substrate subjected to IBO below 1 keV.

Professional identity and organisation in a technical occupation: The emergence of chemical engineering in Britain, c. 1915–-30

by Sean Johnston

Colin Divall, James F. Donelly and Sean F. Johnston

The emergence in Britain of chemical engineering, by mid century the fourth largest engineering specialism, was a... more The emergence in Britain of chemical engineering, by mid century the fourth largest engineering specialism, was a hesitant and long drawn out process. This article analyses the organisational politics behind the recognition of the technical occupation and profession from the First World War through to the end of the 1920s. The collective sense of professional identity among nascent 'chemical engineers' developed rapidly during this time owing to associations which promoted their cause among potential patrons.

Proteome-wide post-translational modification statistics: frequency analysis and curation of the swiss-prot database

by George Khoury

Published in Nature Scientific Reports, 2011

Post-translational modifications (PTMs) broadly contribute to the recent explosion of proteomic data and possess a... more Post-translational modifications (PTMs) broadly contribute to the recent explosion of proteomic data and possess a complexity surpassing that of protein design. PTMs are the chemical modification of a protein after its translation, and have wide effects broadening its range of functionality. Based on previous estimates, it is widely believed that more than half of proteins are glycoproteins. Whereas mutations can only occur once per position, different forms of post-translational modifications may occur in tandem. With the number and abundances of modifications constantly being discovered, there is no method to readily assess their relative levels. Here we report the relative abundances of each PTM found experimentally and putatively, from high-quality, manually curated, proteome-wide data, and show that at best, less than one-fifth of proteins are glycosylated. We make available to the academic community a continuously updated resource (http://selene.princeton.edu/PTMCuration) containing the statistics so scientists can assess “how many” of each PTM exists.

Computational design of Candida boidinii xylose reductase for altered cofactor specificity

by George Khoury

CO2 Capture using Whey Protein Isolate

by Md Imtiaz Ul Islam

Md. Imtiaz-Ul-Islam, L Hong & T.A.G. Langrish (2011) CO2 Capture using Whey Protein Isolate, Chemical Engineering Journal, Volume 17, Issue 3, Page 1069-1081

Microwave pyrolysis, a novel process for recycling waste automotive engine oil

by Su Shiung Lam

Published in Energy, 35 (7), 2985-2991 (2010).

Used automotive engine oil was treated using a microwave-induced pyrolysis process, with the intention of assessing... more Used automotive engine oil was treated using a microwave-induced pyrolysis process, with the intention of assessing the suitability of the process in recovering valuable products from this otherwise difficult to dispose of waste. The resulting pyrolysis gases were condensed into liquid oil; the yield and composition of the recovered oil and remaining incondensable gases was determined, and these were compared with those arising from fresh oil. Process temperature was shown to have a significant effect on the overall yield and formation of the recovered oils. The recovered liquid and gaseous pyrolysis products contained various light hydrocarbons which could be used as a valuable fuel and as an industrial feedstock. Our results indicate that microwave pyrolysis shows extreme promise as a means for disposing of problematic waste oil. The recovery of commercially valuable products shows advantage over traditional, more destructive disposal methods, and suggests excellent potential for scaling the process to the commercial level.

Pyrolysis Using Microwave Heating: A Sustainable Process for Recycling Used Car Engine Oil

by Su Shiung Lam

Published in Industrial & Engineering Chemistry Research, 49, 10845-10851 (2010).

We demonstrate the applicability of pyrolysis using microwave heating to recycle used car engine oil. Waste oil was... more We demonstrate the applicability of pyrolysis using microwave heating to recycle used car engine oil. Waste oil was thermally cracked in an inert microwave-heated bed of particulate carbon from which oxygen was excluded, and the relationship between temperature, the chemical composition of the hydrocarbons, and the metal fraction produced was determined. A reaction temperature of 600 °C provided the greatest yield of commercially valuable products: the recovered liquid oils were composed of light paraffins and aromatic hydrocarbons that could be used as industrial feedstock; the remaining incondensable gases comprised light hydrocarbons that could potentially be used as a fuel source to power the process. In addition, the recovered liquid oils showed a significant reduction in the metal contaminants accumulated throughout their use cycle: a 93−97% reduction in Cu, Ni, Pb, Zn, Fe; a 46% reduction in Cd; and a 32% reduction in Cr. Our results indicate that microwave pyrolysis shows exceptional promise as a means for recycling and treating problematic waste oil.

Microwave-heated pyrolysis of waste automotive engine oil: Influence of operation parameters on the yield, composition, and fuel properties of pyrolysis oil

by Su Shiung Lam

Published in Fuel, 92(1), 327-339, 2012

The pyrolysis of waste automotive engine oil was investigated using microwave energy as the heat source, and the yield... more The pyrolysis of waste automotive engine oil was investigated using microwave energy as the heat source, and the yield and characteristics of the pyrolysis oils (i.e. elemental analysis, hydrocarbon composition, and potential fuel properties) are presented and discussed. The microwave-heated pyrolysis generated an 88 wt% yield of condensable pyrolysis oil with fuel properties (e.g. density, calorific value) comparable to traditional liquid transportation fuels derived from fossil fuel. Examination of the composition of the oils showed the formation of light aliphatic and aromatic hydrocarbons that could also be used as a chemical feedstock. The oil product showed significantly high recovery (90%) of the energy present in the waste oil, and is also relatively contaminant free with low levels of sulphur, oxygen, and toxic PAH compounds. The high yield of pyrolysis oil can be attributed to the unique heating mode and chemical environment present during microwave-heated pyrolysis. This study extends existing findings on the effects of pyrolysis process conditions on the overall yield and formation of the recovered oils, by demonstrating that feed injection rate, flow rate of purge-gas, and heating source influence the concentration and the molecular nature of the different hydrocarbons formed in the pyrolysis oils. The microwave-heated pyrolysis can be performed in a continuous operation, and the apparatus described which is fitted with magnetrons capable of delivering 5 kW of microwave power is capable of treating waste oil at a feed rate of 5 kg/h with a positive energy ratio of 8 (energy content of hydrocarbon products/electrical energy supplied for microwave heating) and a net energy output of 179390 kJ/h. Our results indicate that microwave-heated pyrolysis shows exceptional promise as a means for recycling and treating problematic waste oil.

Characterisation of Middle-Distillates by Comprehensive Two-Dimensional Gas Chromatography (GC× GC): A Powerful Alternative for Performing Various Standard …

by Laurent Duval

"Co-authored with VENDEUVRE Colombe ; RUIZ-GUERRERO Rosario ; BERTONCINI Fabrice; DUVAL Laurent ; THIEBAUT Didier ; HENNION Marie-Claire"

The detailed characterisation of middle distillates is essential for a better understanding of reactions involved in... more The detailed characterisation of middle distillates is essential for a better understanding of reactions involved in refining process. Owing to higher resolution power and enhanced sensitivity, comprehensive two-dimensional gas chromatography (GC x GC) is a powerful tool for improving characterisation of petroleum samples. The aim of this paper is to compare GC x GC and various ASTM methods - gas chromatography (GC), liquid chromatography (LC) and mass spectrometry (MS) - for group type separation and detailed hydrocarbon analysis. Best features of GC x GC are demonstrated and compared to these techniques in terms of cost, time consumption and accuracy. In particular, a new approach of simulated distillation (SimDis-GC x GC) is proposed: compared to the standard method ASTM D2887 it gives unequal information for better understanding of conversion process.

Flow and mass transfer of fully resolved bubbles in non‐Newtonian fluids

by Stefan Radl

DNS-based prediction of the selectivity of fast multiphase reactions: Hydrogenation of nitroarenes

by Stefan Radl

Mixing characteristics of wet granular matter in a bladed mixer

by Stefan Radl

Evaluating Factors That Influence Microbial Synthesis Yields by Linear Regression with Numerical and Ordinal Variables

by Yogesh Goyal

Biotechnology and Bioengineering, Wiley Publications 2011

In the production of chemicals via microbial fermentation, achieving a high yield is one of the most important... more In the production of chemicals via microbial fermentation, achieving a high yield is one of the most important objectives. We developed a statistical model to analyze influential factors that determine product yield by compiling data obtained from engineered Escherichia coli developed within last 10 years. Using both numerical and ordinal variables (e.g., enzymatic steps, cultivation conditions, and genetic modifications) as input parameters, our model revealed that cultivation modes, nutrient supplementation, and oxygen conditions were the three significant factors for improving product yield. Generally, the model showed that product yield decreases as the number of enzymatic steps in the biosynthesis pathway increases (7–9% loss of yield per enzymatic step). Moreover, overexpression of enzymes or removal of competitive pathways (e.g., knockout) does not necessarily result in an amplification of product yield (P-value >0.1), possibly because of limited capacity in the biosynthesis pathway to accommodate an increase in flux. The model not only provides general guidelines for metabolic engineering and fermentation processes, but also allows a priori estimation and comparison of product yields under designed cultivation conditions. Biotechnol. Bioeng. 2011; 108:893–901. © 2010 Wiley Periodicals, Inc.