Biochemical and Biomolecular Engineering Commons^™

Quantifying And Resolving Multiple Vector Transformants In S. Cerevisiae Plasmid Libraries, Thomas C. Scanlon, Elizabeth C. Gray, Karl E. Griswold

Dartmouth Scholarship

In addition to providing the molecular machinery for transcription and translation, recombinant microbial expression hosts maintain the critical genotype-phenotype link that is essential for high throughput screening and recovery of proteins encoded by plasmid libraries. It is known that Escherichia coli cells can be simultaneously transformed with multiple unique plasmids and thusly complicate recombinant library screening experiments. As a result of their potential to yield misleading results, bacterial multiple vector transformants have been thoroughly characterized in previous model studies. In contrast to bacterial systems, there is little quantitative information available regarding multiple vector transformants in yeast. Saccharomyces cerevisiae is the …

Characterisation And Mechanical Testing Of Hydrothermally Treated Ha/Zro2 Composites, D. J. Curran, T. J. Fleming, G. Kawachi, C. Ohtsuki, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

Hydrothermal treatment is traditionally employed to improve the sinterability of powder compacts by reducing porosity and increasing apparent density. The effect of hydrothermal treatment on green powder compacts has been assessed in order to better understand how treatment may affect the sinter ability of the bodies. Laboratory synthesized nano sized hydroxyapatite (HA) and a commercial zirconia (ZrO₂) powder have been ball milled together to create composite mixtures containing 0-5 wt% ZrO₂ loadings. Disc shaped bodies have been formed using uniaxial and subsequent isostatic pressure. The resultant coherent samples were subjected to hydrothermal treatment at either 120 or …

Fabrication Of Spherical Cao-Sro-Zno-Sio2 Particles By Sol-Gel Processing, Ill Yong Kim, Mark R. Towler, Anthony Wren, Chikara Ohtsuki

Chemical and Biochemical Engineering Faculty Research & Creative Works

This study was concerned with the fabrication of ceramic CaO-SrO-ZnO-SiO₂ spherical particles, which are novel candidates for the glass phase in glass polyalkenoate cements (GPCs). GPCs made from these glasses have potential as bone cements because, unlike conventional GPCs, they do not contain aluminum ions, which inhibit the calcification of hydroxyapatite in the body. The glass phase of GPCs require a controllable glass morphology and particle size distribution. Sol-gel processing can potentially be used to fabricate homogenous ceramic particles with controlled morphology. However, a thorough study on preparation conditions of spherical CaO-SrO-ZnO-SiO₂ particles by sol-gel processing has, to …

Analysis Of Γ-Irradiated Synthetic Bone Grafts By ²⁹Si Mas-Nmr Spectroscopy, Calorimetry And Xrd, D. Boyd, S. Murphy, Mark R. Towler, A. W. Wren, S. Hayakawa

Chemical and Biochemical Engineering Faculty Research & Creative Works

Ca-Sr-Zn-Si glasses have demonstrated excellent biocompatibility both in vitro using the MTT assay with L929 mouse fibroblast cells, and in vivo using healthy and ovariectomized female Wistar rats. However, the biological evaluation of the materials was performed on glass granules that were autoclaved, rather than γ-irradiated; the sterilisation procedure required prior to implantation of these materials in the human body. Given the fact that when a glass is exposed to ionizing radiation changes in its physical properties can take place, it is imperative to determine whether the structure of such glasses will be altered as a result of exposure to …

The Effect Of Glass Synthesis Route On Mechanical And Physical Properties Of Resultant Glass Ionomer Cements, A. Wren, O. M. Clarkin, F. R. Laffir, C. Ohtsuki, I. Y. Kim, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

Glass ionomer cements (GICs) have potential orthopaedic applications. Solgel processing is reported as having advantages over the traditional melt-quench route for synthesizing the glass phase of GICs, including far lower processing temperatures and higher levels of glass purity and homogeneity. This work investigates a novel glass formulation, BT 101 (0.48 SiO₂-0.36 ZnO-0.12 CaO-0.04 SrO) produced by both the melt-quench and the solgel route. The glass phase was characterized by X-ray diffraction (XRD) to determine whether the material was amorphous and differential thermal analysis (DTA) to measure the glass transition temperature (T_g). Particle size analysis (PSA) was …

Comparison Of Failure Mechanisms For Cements Used In Skeletal Luting Applications, O. Clarkin, D. Boyd, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

Glass Polyalkenoate Cements (GPCs) based on strontium calcium zinc silicate (Sr-Ca-Zn-SiO₂) glasses and low molecular weight poly (acrylic acid) (PAA) have been shown to exhibit suitable compressive strength (65 MPa) and flexural strength (14 MPa) for orthopaedic luting applications. In this study, two such GPC formulations, alongside two commercial cements (Simplex ® P and Hydroset™) were examined. Fracture toughness and tensile bond strength to sintered hydroxyapatite and a biomedical titanium alloy were examined. Fracture toughness of the commercial Poly(methyl methacrylate) cement, Simplex® P, (3.02 MPa m^1/2) was superior to that of the novel GPC (0.36 MPa …

Comparison Of An Experimental Bone Cement With A Commercial Control, Hydroset™, O. M. Clarkin, D. Boyd, S. Madigan, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

Glass polyalkenoate cements based on strontium calcium zinc silicate glasses (Zn-GPCs) and high molecular weight polyacrylic acids (PAA) (MW; 52,000-210,000) have been shown to exhibit mechanical properties and in vitro bioactivity suitable for arthroplasty applications. Unfortunately, these formulations exhibit working times and setting times which are too short for invasive surgical applications such as bone void filling and fracture fixation. In this study, Zn-GPCs were formulated using a low molecular weight PAA (MW; 12,700) and a modifying agent, trisodium citrate dihydrate (TSC), with the aim of improving the rheological properties of Zn-GPCs. These novel formulations were then compared with commercial …

Proceedings Of The Scientific Conference On Energy And It At Alvsjo Fair, Stockholm March 11-12, 2009 In Connection With The “Energitinget 2009, Dr. Erik Dahlquist, Dr. Jenny Palm

Dr. Erik Dahlquist

This book contains the proceedings from the Energy and IT conference at Alvsjo Energy conference "Energitinget" arranged by Swedish Energy Agency, with approximately 2500 visitors. The papers contain both technical and social science papers, relating to both energy efficiency in buildings and in industry.

Ptau Bimetallic Heteronanostructures Made By Post-Synthesis Modification Of Pt-On-Au Nanoparticles, Zhenmeng Peng

Chemical, Biomolecular, and Corrosion Engineering Faculty Research

imetallic PtAu heteronanostructures have been synthesized from Pt-on-Au nanoparticles, which were made from platinum acetylacetonate and gold nanoparticles. Using the Pt-on-Au nanoparticles as precursors, Ptsurface rich PtAu bimetallic heteronanostructures can be produced through controlled thermal treatments, as confirmed by field emission high-resolution transmission electron microscopy (HR-TEM) and elemental mapping using a high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM). Oxidation of formic acid was used as a model reaction to demonstrate the effects of varying composition and surface structure on the catalytic performance of PtAu bimetallic nanostructures. Cyclic voltammetry (CV) showed that these carbon-supported PtAu heteronanostructures were much more active …

Effects Of Growth Media Ph And Reaction Water Activity On The Conversion Of Acetophenone To (S)-1-Phenylethanol By Saccharomyces Cerevisiae Immobilized On Celite 635 And In Calcium Alginate, Nicholas P. Coleman, Czarena Crofcheck, Sue E. Nokes, Barbara L. Knutson

Biosystems and Agricultural Engineering Faculty Publications

Biologically catalyzed reactions often produce enantiomers of the product; however, only one configuration is desired. Reaction conditions are known to affect enantiomer ratios and reaction kinetics, but little is known regarding the effect of processing conditions on whole-cell biocatalysis. Saccharomyces cerevisiae cells were grown in batch on glucose at pH = 4, 5, and 7, and then immobilized on Celite beads or in calcium alginate beads and used as the biocatalyst for the conversion of acetophenone in hexane to (S)-1-phenylethanol at water activities of 0.37, 0.61, and 0.80. S. cerevisiae was used as a model microorganism for the whole-cell catalyzed …

Biofilm Inhibitory Coatings Formulated From Glass Polyalkenoate Cement Chemistry: An Evaluation Of Their Adhesive Nature, A. Coughlan, D. Boyd, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

Researchers evaluated the adhesive nature of the biofilm inhibitory coatings formulated from glass polyalkenoate cement (GPC) chemistry with the aim to establish the novel testing modality by modifying the conventional T-peel tests. Special consideration was given to determine the resistance of a bonded assembly of two adherents having at least one adherent flexible to quantify the bond between tape and a surgical metal substrate bonded by a luting GPC. The delaminated tape surface was examined by scanning electron microscopy (SEM) with an accelerating voltage of 20 K V to determine whether failure of the bond was adhesive of cohesive in …

Temperature Influence And Heat Management Requirements Of Microalgae Cultivation In Photobioreactors, Thomas Hagen Mehlitz

Master's Theses

Microalgae are considered one of the most promising feedstocks for biofuel production for the future. The most efficient way to produce vast amounts of algal biomass is the use of closed tubular photobioreactors (PBR). The heat requirement for a given system is a major concern since the best algae growth rates are obtained between 25-30 °C, depending on the specific strain. A procedure to determine temperature influence on algal growth rates was developed for a lab-scale PBR system using the species Chlorella. A maximum growth rate of 1.44 doublings per day at 29 °C (optimal temperature) was determined. In addition, …

Computed Tomographic Investigation Of The Influence Of Gas Sparger Design On Gas Holdup Distribution In A Bubble Column, B. C. Ong, P. Gupta, A. Youssef, M. (Muthanna) H. Al-Dahhan, M. P. Duduković

Chemical and Biochemical Engineering Faculty Research & Creative Works

The Effect of Gas Sparger Design on the Gas Holdup Radial Profile in a Bubble Column (With a Diameter of 0.162 M) Has Been Studied using Γ-Ray Computed Tomography (CT). Six Different Configurations of Gas Spargers Were Examined, using an Air-Water System for Selected Superficial Gas Velocities from 2 Cm/s to 30 Cm/s, Covering the Homogeneous and Heterogeneous (Churn-Turbulent) Flow Regimes. Two Operating Pressures Were Used: 1 and 4 Atm. Differences Were Found between the Gas Holdup Distributions Produced by Different Spargers at Dimensionless Radii of R/R < 0.8 in the Central Region of the Column. the Cross and Single Nozzle Spargers Produced Closely Similar Gas Holdup Distributions, While the Perforated Plate Sparger Produced a Higher Gas Holdup When Compared to Other Spargers with the Same Percentage Open Area (POA). at 4 Atm, the Sparger Design Did Not Have a Significant Effect on the Gas Holdup Profiles, Compared to Atmospheric Pressure, Except for the Case of the Single-Hole Sparger, Which Was Found to Yield a Higher Gas Holdup. © 2009 American Chemical Society.

More On Powers Of Ten, Morton Sternheim

Nanotechnology Teacher Summer Institutes

A powers of ten personation and activity adapted from the Nanosense project:

http://nanosense.sri.com/activities/sizematters/index.html

Metabolic Engineering Of Escherichia Coli For Efficient Conversion Of Glycerol Into Ethanol, Cong T. Trinh, Friedrich Srienc

Faculty Publications and Other Works -- Chemical and Biomolecular Engineering

Based on elementary mode analysis, an Escherichia coli strain was designed for efficient conversion of glycerol to ethanol. By using nine gene knockout mutations, the functional space of the central metabolism of E. coli was reduced from over 15,000 possible pathways to a total of 28 glycerol-utilizing pathways that support cell function. Among these pathways are eight aerobic and eight anaerobic pathways that do not support cell growth but convert glycerol into ethanol with a theoretical yield of 0.50 g ethanol/g glycerol. The remaining 12 pathways aerobically coproduce biomass and ethanol from glycerol. The optimal ethanol production depends on the …

Antibacterial Properties Of A Tri-Sodium Citrate Modified Glass Polyalkenoate Cement, A. W. Wren, D. Boyd, R. Thornton, J. C. Cooney, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

Primary deep infection following joint replacement surgery accounts for 7% of all revisions. Glass polyalkenoate cements (GPCs) have previously been shown to exhibit antibacterial properties. The present study had two objectives. The first was to determine if addition of tri-sodium citrate (TSC) to the powder phase of an Al-free GPC (0.04 SrO-0.12 CaO-0.36 ZnO-0.48 SiO2, by mole fraction) enhanced the resultant cement's antibacterial properties against three strains of bacteria that are commonly found in periprosthetic sites following total joint replacements (TJRs); namely, E. coli, B. fragilis, and S. epidermidis. Four cement sets were prepared, which contained 0 wt% TSC (control), …

The Effect Of Sodium On The Catalytic Activity Of Zno-Al2o3/Zsm-5 And Sno-Al2o3/Zsm-5 For The Transesterification Of Vegetable Oil With Methanol, Manhoe Kim, Shuli Yan, Steven O. Salley, K.Y. Simon Ng

National Biofuels Energy Laboratory

In order to elucidate the effect of sodium on the activity of ZSM-5 supported metal oxides catalysts (ZnO-Al2O3/ZSM-5 and SnO-Al2O3/ZSM-5) for the transesterification of soybean oil with methanol, ZSM-5 supported metal oxides were prepared with and without sodium hydroxide by impregnation. The metal compositions of the ZSM-5 supported metal oxide catalysts and the metal concentrations dissolved from the catalysts to the methylester phase were measured by SEM-EDS and inductive coupled plasma spectroscopy, respectively. The catalytic activity of ZnO-Al2O3/ZSM-5 and SnO-Al2O3/ZSM-5 containing sodium did not originate from surface metal oxides sites, but from surface sodium sites or dissolved sodium leached from …

Dna Assembler, An In Vivo Genetic Method For Rapid Construction Of Biochemical Pathways, Zengyi Shao, Hua Zhao, Huimin Zhao

Zengyi Shao

The assembly of large recombinant DNA encoding a whole biochemical pathway or genome represents a significant challenge. Here, we report a new method, DNA assembler, which allows the assembly of an entire biochemical pathway in a single step via in vivo homologous recombination in Saccharomyces cerevisiae. We show that DNA assembler can rapidly assemble a functional d-xylose utilization pathway (∼9 kb DNA consisting of three genes), a functional zeaxanthin biosynthesis pathway (∼11 kb DNA consisting of five genes) and a functional combined d-xylose utilization and zeaxanthin biosynthesis pathway (∼19 kb consisting of eight genes) with high efficiencies (70 - 100%) …

Microfabrication Of Homogenous, Asymmetric Cell-Laden Hydrogel Capsules, Qiaobing Xu, Tram T. Dang, Kaitlin M. Bratlie, Ivy Chen, Robert Langer, Daniel G. Anderson

Kaitlin M. Bratlie

Cell encapsulation has been broadly investigated as a technology to provide immunoprotection for transplanted endocrine cells. Here we develop a new fabrication method that allows for rapid, homogenous microencapsulation of insulin-secreting cells with varying microscale geometries and asymmetrically modified surfaces. Micromolding systems were developed using polypropylene mesh, and the material/surface properties associated with efficient encapsulation were identified. Cells encapsulated using these methods maintain desirable viability and preserve their ability to proliferate and secrete insulin in a glucose-responsive manner. This new cell encapsulation approach enables a practical route to an inexpensive and convenient process for the generation of cell-laden microcapsules without …

Understanding The Dielectric Properties Of Heat-Treated Carbon Nanofibers At Terahertz Frequencies: A New Perspective On The Catalytic Activity Of Structured Carbonaceous Materials, Edward P.J. Parrott, J. Axel Zeitler, James Mcgregor, Shu-Pei Oei, Husnu Emrah Unalan, Swee-Ching Tan, William I. Milne, Jean-Philippe Tessonnier, Robert Schlogl, Lynn F. Gladden

Jean-Philippe Tessonnier

Terahertz time domain spectroscopy (THz-TDS) has been used to study the electrical and optical properties of a series of carbon nanofibers (CNFs) that have undergone different heat treatments. The high-temperature heat-treated (HHT) sample displayed increased absorption and real refractive indices across the range 0.3-3.5 THz when compared to the low-temperature heat-treated (LHT) and pyrolitically stripped (PS) samples. The experimental results were fitted by using a Drude-Lorentz model and an effective medium approximation to yield the electrical parameters of the sample such as the plasma frequency, phonon mode frequency, and oscillator strength. These parameters were used to rationalize the differences as …

Simulation Of Corn Stover And Distillers Grains Gasification With Aspen Plus, Ajay Kumar, Hossein Noureddini, Yaşar Demirel, David Jones, Milford Hanna

Yaşar Demirel Publications

A model was developed to simulate the performance of a lab‐scale gasifier and predict the flowrate and composition of product from given biomass composition and gasifier operating conditions using Aspen Plus software. Mass balance, energy balance, and minimization of Gibbs free energy during the gasification were applied to determine the product gas composition. Carbon conversion efficiency and tar content were provided to the model as inputs as these could not be predicted by the model based on minimization of Gibbs free energy. Experiments for validation of the model were performed on a lab‐scale fluidized bed gasifier using corn stover and …

Preliminary Investigation Of Novel Bone Graft Substitutes Based On Strontium-Calcium-Zinc-Silicate Glasses, D. Boyd, G. Carroll, Mark R. Towler, C. Freeman, P. Farthing, I. M. Brook

Chemical and Biochemical Engineering Faculty Research & Creative Works

Bone graft procedures typically require surgeons to harvest bone from a second site on a given patient (Autograft) before repairing a bone defect. However, this results in increased surgical time, excessive blood loss and a significant increase in pain. In this context a synthetic bone graft with excellent histocompatibility, built in antibacterial efficacy and the ability to regenerate healthy tissue in place of diseased tissue would be a significant step forward relative to current state of the art philosophies. We developed a range of calcium-strontium-zinc-silicate glass-based bone grafts and characterized their structure and physical properties, then evaluated their in vitro …

The Development Of Humans – A Study Including Languages, Cultures, Religions And Genetics, Dr. Erik Dahlquist, Dr. Allan Dahlquist

Dr. Erik Dahlquist

The book covers the development of culture, religion, language and genetics of the human population since prehistory. Four main cultures have spread around the globe: 1) Monosyllabic language people with ancestor cult 2) Austroasiatic people with sun worshipping and megalit graves. Counting with 20 as the base 3) Uralic speaking people with kings from the sky, and strong city states. Moon and mother godess. Don´t differentiate between male and female, he and she. 4) Inflectual language speaking people with sky gods and cattles. Indoeuropeans. Often endings differentiating he and she. Shows how original cultures are refelected in todays society.