Techno-economic assessment of poly-3-hydroxybutyrate (PHB) production from methane - the case for thermophilic bioprocessing

A major obstacle preventing the large scale production of polyhydroxyalkanoates (PHAs) has been the lack of a reliable, low cost, large volume feedstock. The abundance and relatively low price of methane therefore marks it as a substrate of interest. This paper presents a techno-economic assessment of the production of poly-3-hydroxybutyrate (PHB) from methane. ASPEN Plus was used for process design and simulation. The design and economic evaluation is presented for production of 100,000 t/a PHB through methanotrophic fermentation and acetone-water solvent extraction. Production costs were estimated at $4.1-$6.8/kg PHA, which compares against a median price of $7.5/kg from other studies. Raw material costs are reduced from 30 to 50$3.2-5.4/kg PHA; it is noted that PHB producing thermophilic methanotrophs are yet to be isolated. Energy consumption for air compression and biomass drying were also identified as significant capital and operating costs and therefore optimisation of bioreactor height and pressure and biomass moisture content should be considered in future research

Interfering ribonucleic acids that suppress expression of multiple unrelated genes

<p>Abstract</p> <p>Background</p> <p>Short interfering RNAs (siRNAs) have become the research tool of choice for gene suppression, with human clinical trials ongoing. The emphasis so far in siRNA therapeutics has been the design of one siRNA with complete complementarity to the intended target. However, there is a need for multi-targeting interfering RNA in diseases in which multiple gene products are of importance. We have investigated the possibility of using a single short synthetic duplex RNA to suppress the expression of <it>VEGF-A </it>and <it>ICAM-1</it>; genes implicated in the progression of ocular neovascular diseases such as diabetic retinopathy.</p> <p>Results</p> <p>Duplex RNA were designed to have incomplete complementarity with the 3'UTR sequences of both target genes. One such duplex, CODEMIR-1, was found to suppress VEGF and ICAM-1 by 90 and 60%, respectively in ARPE-19 cells at a transfected concentration of 40 ng/mL. Use of a cyan fusion reporter with target sites constructed in its 3'UTR demonstrated that the repression of VEGF and ICAM-1 by CODEMIR-1 was indeed due to interaction with the target sequence. An exhaustive analysis of sequence variants of CODEMIR-1 demonstrated a clear positive correlation between activity against VEGF (but not ICAM-1) and the length of the contiguous complementary region (from the 5' end of the guide strand). Various strategies, including the use of inosine bases at the sites of divergence of the target sequences were investigated.</p> <p>Conclusion</p> <p>Our work demonstrates the possibility of designing multitargeting dsRNA to suppress more than one disease-altering gene. This warrants further investigation as a possible therapeutic approach.</p

Nanoporous organosilica membrane for water desalination: theoretical study on the water transport

An unconventional nanoporous organosilica membrane has been tested in a vacuum membrane distillation (MD) process for water desalination. We propose a modified approach to understand the transport mechanism of water molecules through the nanopores of this membrane. The modified approach stems from the fact that the membrane has a hydrophilic surface (contact angle 80% increase in permeation flux if the pore size increased from 2 to 3 nm at 60 degrees C. However, pore wetting is expected if d(p) > 3,4 nm, particularly at low temperatures where the slower evaporation rate promoted greater pore intrusion. Concentration polarization was shown to be negligible which agreed well with experimentally observed water fluxes which remained relatively constant despite feed salinity increasing from 0 to 150 g L-1. Lastly, the membrane hydrophilicity was found to impact on water flux and pore intrusion in a complex relationship with pore size. Ultimately, hydrophilic pores less than 3 urn in diameter offer a good combination of good water flux and minimal water intrusion suggesting that ordered mesoporous organosilica membranes have potential in MD applications. (C) 2015 Elsevier B.V. All rights reserved

Long term and performance testing of NaMg double salts for H2/CO2 separation

This work investigates the synthesis and performance of double salts for H/CO separation. A series of NaMg double salts were prepared based on xMg(NO): yNaCO: zHO and characterised. The best sorbents reached CO uptake of 17.9\ua0wt% at 0.62\ua0MPa and 375\ua0°C. The NaMg double salts preferentially sorbed CO as determined by breakthrough tests. The NaMg double salts were packed in a sorbent bed and tested for H/CO separation at the back end of a water gas shift reactor. The space velocity had the largest impact on the performance of the sorbent bed, as increasing the space velocity from 2.16\ua0×\ua010 to 9.51\ua0×\ua010\ua0s sped up the breakthrough time by 84%. Increasing the feed gas pressure from 0.3 to 0.6\ua0MPa reduced the breakthrough time by ∼45%. The NaMg double salt sorbents were exposed for over 1000\ua0h of continuous temperature including 28 cycles of sorption and desorption, and proved to be stable during changes of operating conditions such as flow rates and pressures

Long term and performance testing of NaMg double salts for H2/CO2 separation

This work investigates the synthesis and performance of double salts for H/CO separation. A series of NaMg double salts were prepared based on xMg(NO): yNaCO: zHO and characterised. The best sorbents reached CO uptake of 17.9\ua0wt% at 0.62\ua0MPa and 375\ua0°C. The NaMg double salts preferentially sorbed CO as determined by breakthrough tests. The NaMg double salts were packed in a sorbent bed and tested for H/CO separation at the back end of a water gas shift reactor. The space velocity had the largest impact on the performance of the sorbent bed, as increasing the space velocity from 2.16\ua0×\ua010 to 9.51\ua0×\ua010\ua0s sped up the breakthrough time by 84%. Increasing the feed gas pressure from 0.3 to 0.6\ua0MPa reduced the breakthrough time by ∼45%. The NaMg double salt sorbents were exposed for over 1000\ua0h of continuous temperature including 28 cycles of sorption and desorption, and proved to be stable during changes of operating conditions such as flow rates and pressures

High-throughput gene discovery in the rat

The rat is an important animal model for human diseases and is widely used in physiology. In this article we present a new strategy for gene discovery based on the production of ESTs from serially subtracted and normalized cDNA libraries, and we describe its application for the development of a comprehensive nonredundant collection of rat ESTs. Our new strategy appears to yield substantially more EST clusters per ESTs sequenced than do previous approaches that did not use serial subtraction. However, multiple rounds of library subtraction resulted in high frequencies of otherwise rare internally primed cDNAs, defining the limits of this powerful approach. To date, we have generated >200,000 3′ ESTs from >100 cDNA libraries representing a wide range of tissues and developmental stages of the laboratory rat. Most importantly, we have contributed to ∼50,000 rat UniGene clusters. We have identified, arrayed, and derived 5′ ESTs from >30,000 unique rat cDNA clones. Complete information, including radiation hybrid mapping data, is also maintained locally at http://genome.uiowa.edu/clcg.html. All of the sequences described in this article have been submitted to the dbEST division of the NCBI

Reading and Ownership

First paragraph: ‘It is as easy to make sweeping statements about reading tastes as to indict a nation, and as pointless.’ This jocular remark by a librarian made in the Times in 1952 sums up the dangers and difficulties of writing the history of reading. As a field of study in the humanities it is still in its infancy and encompasses a range of different methodologies and theoretical approaches. Historians of reading are not solely interested in what people read, but also turn their attention to the why, where and how of the reading experience. Reading can be solitary, silent, secret, surreptitious; it can be oral, educative, enforced, or assertive of a collective identity. For what purposes are individuals reading? How do they actually use books and other textual material? What are the physical environments and spaces of reading? What social, educational, technological, commercial, legal, or ideological contexts underpin reading practices? Finding answers to these questions is compounded by the difficulty of locating and interpreting evidence. As Mary Hammond points out, ‘most reading acts in history remain unrecorded, unmarked or forgotten’. Available sources are wide but inchoate: diaries, letters and autobiographies; personal and oral testimonies; marginalia; and records of societies and reading groups all lend themselves more to the case-study approach than the historical survey. Statistics offer analysable data but have the effect of producing identikits rather than actual human beings. The twenty-first century affords further possibilities, and challenges, with its traces of digital reader activity, but the map is ever-changing

Schoolbooks and textbook publishing.

In this chapter the author looks at the history of schoolbooks and textbook publishing. The nineteenth century saw a rise in the school book market in Britain due to the rise of formal schooling and public examinations. Although the 1870 Education and 1872 (Scotland) Education Acts made elementary education compulsory for childern between 5-13 years old, it was not until the end of the First World War that some sort form of secondary education became compulsory for all children

MOLECULAR MODELLING OF POLAR AND NON-POLAR ADSORPTION ON CARBON ADSORBENTS

Adsorption is an industrially important process that remains a vibrant and continuing area of research. The current state of the art in theoretical adsorption studies is molecular simulation with its molecular level determinism of thermodynamic behaviour. This thesis aims to investigate a range of adsorption behaviour through the use of Monte Carlo simulation. Through the duration of this project the thermodynamic properties of adsorption isotherms, heats of adsorption and adsorbed phase heat capacities have been studied for a range of fluids from argon to water. Isotherm behaviour has been studied in two different scenarios. The first was to investigate the use of super critical methane adsorption in the determination of an activated carbon pore size distribution (PSD). It was found that this method was viable in the determination of the PSD in only the micropore range. However it was also shown that the use of absolute amounts adsorbed in the fitting of the PSD results in a better estimation of the accessible volume of and adsorption cell compared with the helium expansion method. Isotherms were also studied for polar compounds on highly graphitised surfaces. Isotherms were shown to be sensitive to the type, amount and configuration of functional groups. It was also shown that currently used interaction models for water adsorption on graphite are inadequate and cannot reproduce any feature of experimental isotherms. A clear and unambiguous derivation of the heat of adsorption equations are presented together with equations for the combination of individual simulation isotherms with a PSD to give the heat of adsorption for a solid. Heat of adsorption behaviour is presented for model carbon surfaces and porous solids and their irreducible features examined. The final large constituent of this study is the investigation of the heat capacity of adsorbed layers for argon and polar compounds. The molecular origins of the interesting heat capacity behaviour are clearly demonstrated and for the case of polar compounds are shown to be a clear indicator in the type of clustering occurring on the surface