Organochlorine pesticides (OCPs) were used in agriculture throughout the world for a long time because they are very effective for pest control, but OCPs such as DDT and its metabolites can threaten human health and ecological systems. Although DDT has been banned for use in Canada since 1972, it still persists in Canadian farmland at detectable levels due to its chemical stability. The soils contaminated with DDT require economical remediation strategies because of the low land value and rural location. Although soil washing has been proposed as a possible economical technique to remove DDT, it has very low water solubility and so it is necessary to consider using surfactants to improve the soil-washing process. Building on previous research, we hypothesize that combinations of surfactants can be used to improve the performance of this remediation method. The surfactants Tween 80, Brij 35, and sodium dodecylbenzene sulfonate (SDBS) were selected based on environmental and reported performance criteria. Combinations of surfactants were tested in both batch and leaching column experiments. Experiments indicated that removal efficiency and flowrate in leaching columns were optimized when a mixture of 2% Brij 35 and 0.1% SDBS was employed. The presence of Tween 80 was found to be less effective, possibly due to its higher biodegradability in the soil. Since the measurement of surfactant concentration in the wash solution is important, several methods were tested before finally selecting a simple COD analysis as a surrogate parameter. Using the COD analysis, partitioning experiments were performed to measure the adsorption of surfactant on the soil. For economic reasons, it would be desirable to reuse the surfactant in a washing process. For this purpose, we employed activated carbon to selectively remove the more hydrophobic DDT from the surfactant solutions. Preliminary results have shown that carbon adsorption can remove some DDT, but additional work is required to understand and optimize the process.

Protein stability plays an important role in a wide variety of settings ranging from industrial processes where proteins are used as biocatalysts to medical settings where misfolded proteins are implicated in disease. Understanding protein stability will allow design of improved bioprocess and pharmaceutical formulations as well as aid in the development of therapies for protein-based diseases. The effects of dissolved salts on protein kinetic stability are studied here. We find that ion-solvent interactions, characterized by the Jones-Dole B-viscosity coefficient, are strong indicators of salt effects on protein deactivation. This finding is used to develop a model for predicting protein deactivation in salt solutions in terms of two competing processes. Since protein unfolding and aggregation can lead to a number of protein misfolding diseases, we test the applicability of our model for describing salt effects on transthyretin aggregation. As the factors contributing to protein stability become more understood, the use of enzymes as biocatalyst for industrial process will increase, and the need for enzymes active in a wide range of reaction media will increase. We have developed a process using an enzyme in combination with organic-aqueous tunable solvents (OATS) which allows for monophasic reaction of the enzyme with hypdrophobic substrates. The reaction mixture can be separated into two phases by the addition of carbon dioxide pressure. This separation allows for both convenient recovery of the hydrophobic reaction product from the organic phase as well as recycle of the enzyme in the aqueous phase. Overall reaction conversions of 80% and little enzyme activity loss are observed after six reaction cycles.

Abstract After the ban against private-owned gas service stations was lifted in 1987, some domestic trading firms took advantage of the special feature of gasoline products as well as Taiwan¡¦s unique oil price structure to import low-quality oil products for blending into gasoline-equivalent products, which would then be sold to independent service station owners mushrooming in accordance with the oil market deregulation. According to the statistics of import/export at Taiwan customs and the comparison between supply and demand of relative industries, it is agreed that an annual total of approximate 400,000 kiloliters of various imported oil products would be blended into gasoline or diesels for sale. Moreover, as Taiwan government has been continuously providing a 14% oil price subsidy against a sluggish fishing industry caused by depleting fishing resources, the fishing fuels in glut, at an estimate of 410, 000 kiloliters a year, would be illegally sold as diesel in domestic gas service stations for higher profits. These practices have not only directly affected tax revenues of local governments, but also infringed upon the legal rights of petroleum refineries, putting the orderliness of petroleum production and sale in jeopardy. In addition, as such illicit practices are usually carried out near makeshift storage tanks with ineligible filling facilities, they have posed great threats to public safety and environment. As it is difficult to detect and thereby root out the underground transactions of such inferior gasoline and diesels, the police that was authorized insufficiently on legal aspects would carry out inspections at key roads and intersections only passively, which has posed but limited intimidation over illegal transactions of unqualified gasoline products. Realizing the facts, this survey takes the historical data on relative factors and market survey figures as basis for calculation and analysis, which is used then to assume the normal demand of gasoline and diesel markets and to establish a conclusive alarming model for flow direction. Besides, it obtains affecting variables such as market segmentation, channel characteristics, customer behaviors, price gap and business environments through interviews and questionnaires, to determine limits on the alarming model and the alarming value. Comparing with the actual consumption of gasoline and diesels, we can then judge if there remains any abnormality concerning the sales volume of gasoline and diesels. If any abnormal sign shown, we can check the alarming model item by item for timely management and control, so as to supervise and check the underground transactions of inferior gasoline and diesels. We also hope that the survey report on ¡§the Alarming Model over the Flow of Inferior Gasoline and Diesels and Its Application¡¨ could provide practical references for the detection and elimination of inferior gasoline and diesels so that the illicit and unsafe practice could be inhibited once and for all.

Here, we present the program QContacts, which implements Voronoi polyhedra to determine atomic and residue contacts across the interface of a protein-protein interaction. While QContacts also describes hydrogen bonds, ionic pair and salt bridge interactions, we focus on QContacts’ identification of atomic contacts in a protein interface compared against the current methods. Initially, we investigated in detail the differences between QContacts, radial cutoff and Change in Solvent Accessible Surface Area (delta-SASA) methods in identifying pair-wise contacts across the binding interface. The results were assessed based on a set of 71 double cycle mutants. QContacts excelled at identifying knob-in-hole contacts. QContacts, closest atom radial cutoff and the delta-SASA methods performed well at picking out direct contacts; however, QContacts was the most accurate in excluding false positives. The significance of the differences identified between QContacts and previous methods was assessed using pair-wise contact frequencies in a broader set of 592 protein interfaces. The inaccuracies introduced by commonly used radial cutoff methods were found to produce misleading bias in the residue frequencies. This bias could compromise pair-wise potentials that are based on such frequencies. Here we show that QContacts provides a more accurate description of protein interfaces at atomic resolution than other currently available methods. QContacts is available in a web-based form at http://tsailab.tamu.edu/qcons (Fischer et al., 2006).

Self assembled monolayer films (SAMs) deposited on silicon surfaces have gained considerable interest due to their ability to modify surface properties for advanced applications in sensors, MEMS, and NEMS devices. These molecular films are typically deposited on silicon surfaces from solution using a variety of solvents, which can influence the molecular packing and quality of the films. To better understand these effects, we have performed a systematic solvent effect study of the growth of n-Octadecyltrichlorosilane (OTS) on silicon substrates using chloroform, dichloromethane, toluene, benzene and hexadecane. The films were characterized using contact angle measurements, Fourier Transform Infrared Spectroscopy (FTIR), and Atomic Force Microscopy (AFM) to evaluate the SAM growth rate and film quality. Lateral Force Microscopy (LFM) and transmission FTIR were used to characterize the molecular packing. Finally, we used AFM to make adhesion measurements on the films and correlated these results with friction data. These techniques provide a means to characterize the local nanoscale packing of the films. The Hertzian contact model was used to model and describe the adhesion and friction result. Our results show that using hexadecane as the solvent produced OTS films with the highest density molecular packing. By comparing to Langmuir-Blodgett SAM film deposition methods, we show that it is the intermolecular interaction between the solvent molecules and OTS that determines this density. Thus, the structure and chemical properties of the solvent molecule strongly influences the molecular packing, quality, and performance of the SAM film.

Evolutionary rates vary vastly across intraspecific genes and the determinants of these rates is of central concern to the field of comparative genomics. Tradition has held that preservation of protein function conserved the sequence, however mounting evidence implicates the biophysical properties of proteins themselves as the elements that constrain sequence evolution. Of these properties, the exposure of a residue to solvent is the most prevalent determinant of its evolutionary rate due to pressures to maintain proper synthesis and folding of the structure. In this work, we have developed a model that considers the microenvironment of a residue in the estimation of its evolutionary rate. By working within the structural context of a protein's residues, we show that our model is better able to capture the overall evolutionary trends affecting conservation of both the coding sequences and the protein structures from a genomic level down to individual genes. / text

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Organochlorine pesticides (OCPs) were used in agriculture throughout the world for a long time because they are very effective for pest control, but OCPs such as DDT and its metabolites can threaten human health and ecological systems. Although DDT has been banned for use in Canada since 1972, it still persists in Canadian farmland at detectable levels due to its chemical stability. The soils contaminated with DDT require economical remediation strategies because of the low land value and rural location. Although soil washing has been proposed as a possible economical technique to remove DDT, it has very low water solubility and so it is necessary to consider using surfactants to improve the soil-washing process. Building on previous research, we hypothesize that combinations of surfactants can be used to improve the performance of this remediation method. The surfactants Tween 80, Brij 35, and sodium dodecylbenzene sulfonate (SDBS) were selected based on environmental and reported performance criteria. Combinations of surfactants were tested in both batch and leaching column experiments. Experiments indicated that removal efficiency and flowrate in leaching columns were optimized when a mixture of 2% Brij 35 and 0.1% SDBS was employed. The presence of Tween 80 was found to be less effective, possibly due to its higher biodegradability in the soil. Since the measurement of surfactant concentration in the wash solution is important, several methods were tested before finally selecting a simple COD analysis as a surrogate parameter. Using the COD analysis, partitioning experiments were performed to measure the adsorption of surfactant on the soil. For economic reasons, it would be desirable to reuse the surfactant in a washing process. For this purpose, we employed activated carbon to selectively remove the more hydrophobic DDT from the surfactant solutions. Preliminary results have shown that carbon adsorption can remove some DDT, but additional work is required to understand and optimize the process.

In this research, physicochemical changes that took place during roast processing of coffee beans using fluidized air roaster were studied. The results showed that high-temperature-short-time resulted in higher moisture content, higher pH value, higher titratable acidity, higher porous structure in the bean cell tissues, and also produced more aldehydes, ketones, aliphatic acids, aromatic acids, and caffeine than those processed at low-temperature-long-time process. Fourier transform infrared (FTIR) spectroscopy and chemometric analysis showed that clusters for principal components score plots of ground coffee, extracted by a mixture of equal volume of ethyl acetate and water, were well separated. The research indicated that variations in IR-active components in the coffee extracts due to different stages of roast, roasting profiles, and geographical origins can be evaluated by the FTIR technique. / Natural Sciences and Engineering Research Council of Canada (NESRC) and Mother Parkers Tea & Coffee Inc.