Design of Experiments for Screening

The aim of this paper is to review methods of designing screening experiments, ranging from designs originally developed for physical experiments to those especially tailored to experiments on numerical models. The strengths and weaknesses of the various designs for screening variables in numerical models are discussed. First, classes of factorial designs for experiments to estimate main effects and interactions through a linear statistical model are described, specifically regular and nonregular fractional factorial designs, supersaturated designs and systematic fractional replicate designs. Generic issues of aliasing, bias and cancellation of factorial effects are discussed. Second, group screening experiments are considered including factorial group screening and sequential bifurcation. Third, random sampling plans are discussed including Latin hypercube sampling and sampling plans to estimate elementary effects. Fourth, a variety of modelling methods commonly employed with screening designs are briefly described. Finally, a novel study demonstrates six screening methods on two frequently-used exemplars, and their performances are compared

Hydrating softwood and hardwood samples using pure and modified supercritical carbon dioxide

This article describes an in-progress research project that looks to investigate the use of supercritical carbon dioxide (scCO2) for the addition of water to historic and modern, softwood and hardwood samples. The experiments were carried out at 20 MPa and 50 °C, the effects of co-solvent addition, methanol (MeOH), were examined. A three point bend test provided mechanical data for the wood samples treated with both pure and modified scCO2. All the wood samples, with only one exception, saw an increase in Modulus of Rupture (MOR) after being treated with scCO2. Thereby indicating an increased resistance to force in the treated samples. Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopy was performed to help deduce if any trends in the OH/CH and OH/Cellulose peak area ratios could be established with the nature of the treatment and the type of wood used. The development of this technique seeks to be relevant and safe for applications within modern conservation practices, where dry and fragile materials are prevalent

Expression proteomics of UPF1 knockdown in HeLa cells reveals autoregulation of hnRNP A2/B1 mediated by alternative splicing resulting in nonsense-mediated mRNA decay

BACKGROUND: In addition to acting as an RNA quality control pathway, nonsense-mediated mRNA decay (NMD) plays roles in regulating normal gene expression. In particular, the extent to which alternative splicing is coupled to NMD and the roles of NMD in regulating uORF containing transcripts have been a matter of debate. RESULTS: In order to achieve a greater understanding of NMD regulated gene expression we used 2D-DiGE proteomics technology to examine the changes in protein expression induced in HeLa cells by UPF1 knockdown. QPCR based validation of the corresponding mRNAs, in response to both UPF1 knockdown and cycloheximide treatment, identified 17 bona fide NMD targets. Most of these were associated with bioinformatically predicted NMD activating features, predominantly upstream open reading frames (uORFs). Strikingly, however, the majority of transcripts up-regulated by UPF1 knockdown were either insensitive to, or even down-regulated by, cycloheximide treatment. Furthermore, the mRNA abundance of several down-regulated proteins failed to change upon UPF1 knockdown, indicating that UPF1`s role in regulating mRNA and protein abundance is more complex than previously appreciated. Among the bona fide NMD targets, we identified a highly conserved AS-NMD event within the 3` UTR of the HNRNPA2B1 gene. Overexpression of GFP tagged hnRNP A2 resulted in a decrease in endogenous hnRNP A2 and B1 mRNA with a concurrent increase in the NMD sensitive isoforms. CONCLUSIONS: Despite the large number of changes in protein expression upon UPF1 knockdown, a relatively small fraction of them can be directly attributed to the action of NMD on the corresponding mRNA. From amongst these we have identified a conserved AS-NMD event within HNRNPA2B1 that appears to mediate autoregulation of HNRNPA2B1 expression levels

Use of glass transition temperature for stabilization of board's cracks of Eucalyptus grandis

The Eucalyptus grandis logs temperatures were determined and correlated with the board's cracks during steaming. Thermocouples were inserted in the logs center, registering their temperatures during steaming at 90"C. The logs were sawed and the board's cracks measured. It was concluded that: (1) the logistic S-shaped curve explains the logs temperature variation; (2) the logs with diameter of 20 to <25, 25 to <30 and 30 to <35 cm presented, respectively, 84.2"C, 73.1"C and 45.8"C in the steaming; and (3) the cracks lengths significantly decreased in logs that reached the glass transition temperature.<br>As temperaturas em toras de Eucalyptus grandis, durante a vaporização, foram determinadas e correlacionadas com as rachaduras das tábuas. Nos centros das toras foram inseridos termopares e registradas suas temperaturas durante a vaporização à 90"C. As toras foram desdobradas e as rachaduras das tábuas mensuradas. Concluiu-se que: (1) o modelo estatístico sigmoidal logístico explica a variação da temperatura nas toras; (2) as toras com 20 a <25, 25 a <30 e 30 a <35 cm de diâmetro apresentaram, respectivamente, 84,2"C, 73,1"C e 45,8"C ao final da vaporização; e (3) as rachaduras foramsignificativamente menores nas toras que atingiram a temperatura de transição vítrea