Evaluation of a substitute filter medium for removal of haze in beer.

Diatomaceous earth (DE) is widely used in the filtration of beer to remove suspended yeast and other particulate material that can cause cloudiness or haze in the final product. The DE used has a particle size diameter of between 60 and 100 um. However, health and safety concerns arise its human carcinogenic classification in 1997 from Category 2 (Probable Human Carcinogen) to Category 1 (Human Carcinogen) by the IARC. In a confidential study conducted at Adelaide University, zeolite-A, a hydrated aluminosilicate of alkali earth metals, showed promising filtration capabilities when used in the removal of haze in white wine. Zeolite-A is non-toxic via oral, dermal, ocular and respiratory exposure as well as safe for the environment at disposal. An experimental study to investigate zeolite-A as a possible substitute for DE in the brewing industry was therefore undertaken. The particular zeolite-A used was selected as it was judged as nearly the same as that manufactured within the Department of Chemical Engineering, Adelaide University from naturally occurring deposits of kaolin. Two size-grades of zeolite-A (large diameter particles of 125-250 um and small diameter particles of 63-125 um) were selected to cover the particle size range of widely used DE (as Celite 503). These two zeolites, together with filter sand (200 um diameter particle size) and silica were experimentally evaluated against DE in the clarification of beer simulants and commercial beer product. Flux-time experiments on each of three packed beds of each of the five filter media (3.63, 11.23, 18.83 g) with three values of pressure driving force (70, 125, 180 kPa) were carried out in a specially constructed pilot plant, initially in the laboratory and later in situ in a commercial brewing plant. This special pilot plant, together with protocols for the preparation of media, simulated conditions and practices in current use in the brewing industry. The flux obtained from the small grade zeolite-A (particle 63-125 um) was significantly lower compared to DE, i.e. respectively, 22 mLm⁻²s⁻¹ and 390 mLm⁻²s⁻¹ (using 18.83 g media at 180 kPa) Large grade zeolite-A (particle size 125-250 um) showed comparable flux properties to DE with flux rate of 290 mLm⁻²s⁻¹ . Microbiological analyses were carried out initially on eight selected filter media - which also additionally included pumice, perlite and cellulose (as cotton wool) - to assess effectiveness in removing haze forming constituents from a simulated beer (yeast solution) and two home-brewed beer types. The pumice, perlite and cellulose were rejected as alternative filter media because of poor performance in haze removal. Microbiological, chemical and sensory analyses were carried out on each of the five remaining media. Results of the microbial analyses highlighted that DE and zeolite-A were the best filter media because practically all yeast cells were retained on the filter cake from both the simulated beer and the home-brewed beers. With filtration of commercial beers using small grade zeolite-A as the filter medium in situ at Cooper's Brewery an increase in pH value of the filtrate of 2.0 pH units was observed. For large grade zeolite-A the pH increase of the filtrate was less than 0.5 pH units. This increased pH of the filtrate with both grades of zeolite-A was demonstrated to be due to the release of sodium ions from the filter medium. Additional experiments were conducted to exhaust the sodium from the filter media of both the small and large grade zeolite-A. The pH of the filtrates was monitored for between 8 and 16 h of continuous filtration to determine if all sodium could be exhausted from the medium. A practical constraint was that the filter cake became clogged with yeast and other solid particles from the beer haze before a noticeable change in pH of the filtrate could be observed. Sensory analyses of filtrates of each of the five selected media were carried out by 16 industry noses to assess: colour, aroma, taste, clarity and drinkability ( = overall impression). Overall the large grade zeolite-A filtrates compared satisfactorily with the DE filtrates in ratings of differences from the Descriptive Method employed in the brewery industry for colour, taste, aroma, clarity and drinkability. Small grade zeolite-A filtrates however compared poorly where the filtrate was regarded as inferior to DE, filter sand and silica, by all the members of the panel of noses. Small grade zeolite-A was further found to have a significant adverse effect on the filtrate taste using the Triangular Method widely employed commercially for establishing taste. Therefore small grade zeolite-A was deemed an unsuitable filter substitute for DE in the clarification and removal of haze constitutes in commercial beer. Large grade zeolite-A however appears to be a suitable substitute filter medium for DE in the removal of haze constituents in beer. Importantly it can be readily substituted for DE without the need for significant changes in brewery industry process equipment and protocols for preparation. The findings from this study are sufficient to strongly recommend a focused study on contributing chemical and mechanical factors to the (small) pH increase of the filtrate using large grade zeolite-A. It is not known whether a range of zeolites might also provide a practical substitute to DE, present understanding must therefore be said to be limited. Other zeolites proposed for the removal of haze from beer would need to be evaluated experimentally. The pilot plant and procedures developed for this study would be readily applicable for such an undertaking. An important justification for future work is that a suitable substitute for DE such as zeolite-A is seen as timely in view of the significant health risks associated with the established carcinogenic properties of DE. There is no evidence available to show that zeolites have been studied as an alternative to DE for the removal of haze (in beer or wine). Therefore the findings reported in the present study for zeolite-A, together with earlier findings from the polishing of white wine, strongly indicate the basis for development of IP patent(s).Thesis (M.App.Sc.) -- University of Adelaide, Dept. of Chemical Engineering, 200

Baseline model based structural health monitoring method under varying environment

Environment has significant impacts on the structure performance and will change features of sensor measurements on the monitored structure. The effect of varying environment needs to be considered and eliminated while conducting structural health monitoring. In order to achieve this purpose, a baseline model based structural health monitoring method is proposed in this paper. The relationship between signal features and varying environment, known as a baseline model, is first established. Then, a tolerance range of the signal feature is evaluated via a data based statistical analysis. Furthermore, the health indicator, which is defined as the proportion of signal features within the tolerance range, is used to judge whether the structural system is in normal working condition or not so as to implement the structural health monitoring. Finally, experimental data analysis for an operating wind turbine is conducted and the results demonstrate the performance of the proposed new technique

LiNi0.5Mn1.5O4 Thin Films Grown by Magnetron Sputtering under Inert Gas Flow Mixtures as High-Voltage Cathode Materials for Lithium-Ion Batteries

Delivering a commercial high-voltage spinel LiNi0.5Mn1.5O4 (LNMO) cathode electrode for Li-ion batteries would result in a significant step forward in terms of energy density. However, the structural ordering of the spinel and particle size have considerable effects on the cathode material's cyclability and rate capability, which are crucial challenges to address. Here, a novel mid-frequency alternating current dual magnetron sputtering method was presented, using different Ar-N-2 gas mixtures ratios for the process gas to prepare various LNMO thin films with highly controlled morphology and particle size; as determined from X-ray diffraction, Raman spectroscopy and electron microscopy. It resulted in enhanced cycling and rate performance. This processing method delivered N-containing LNMO thin film electrodes with up to 15 % increased discharge capacity at 1 C (120 mAh g(-1)) with respect to standard LNMO (grown under only Ar gas flow) thin film electrodes, along with outstanding rate performance up to 10 C (99 mAh g(-1)) in the operating voltage window 3.5-4.85 V vs. Li+/Li. Besides, electrochemical impedance spectroscopy results showed that the intricate phase transitions present in standard LNMO electrodes were almost suppressed in N-containing LNMO thin films grown under different Ar-N-2 gas flow mixtures

HISTORIA UNIVERSAL

GUÍA DIDÁCTICA / PLANEACIÓN DIDÁCTICA (NMS

Probability distributed time delays: integrating spatial effects into temporal models

Background: In order to provide insights into the complex biochemical processes inside a cell, modelling approaches must find a balance between achieving an adequate representation of the physical phenomena and keeping the associated computational cost within reasonable limits. This issue is particularly stressed when spatial inhomogeneities have a significant effect on system's behaviour. In such cases, a spatially-resolved stochastic method can better portray the biological reality, but the corresponding computer simulations can in turn be prohibitively expensive.Results: We present a method that incorporates spatial information by means of tailored, probability distributed time-delays. These distributions can be directly obtained by single in silico or a suitable set of in vitro experiments and are subsequently fed into a delay stochastic simulation algorithm (DSSA), achieving a good compromise between computational costs and a much more accurate representation of spatial processes such as molecular diffusion and translocation between cell compartments. Additionally, we present a novel alternative approach based on delay differential equations (DDE) that can be used in scenarios of high molecular concentrations and low noise propagation.Conclusions: Our proposed methodologies accurately capture and incorporate certain spatial processes into temporal stochastic and deterministic simulations, increasing their accuracy at low computational costs. This is of particular importance given that time spans of cellular processes are generally larger (possibly by several orders of magnitude) than those achievable by current spatially-resolved stochastic simulators. Hence, our methodology allows users to explore cellular scenarios under the effects of diffusion and stochasticity in time spans that were, until now, simply unfeasible. Our methodologies are supported by theoretical considerations on the different modelling regimes, i.e. spatial vs. delay-temporal, as indicated by the corresponding Master Equations and presented elsewhere

Fragmentation and constitutive response of tailored mesostructured aluminum compacts

The fragmentation and constitutive response of aluminum-based compacts were examined under dynamic conditions using mesostructured powder compacts in which the interfaces between the powders (sizes of 40, 100, and 400 μm) were tailored during the swaging fabrication process. Fragmentation was induced in ring samples of this material through explosive loading and was examined through high speed photography, laser interferometry, and soft capture of fragments. Fragment velocities of around 100 m/s were recorded. The fragment mass distributions obtained correlated in general with the interfacial strength of the compacts as well as with the powder size. Experimental results are compared with fragmentation theories to characterize the behavior of reactive powders based on the material's mesostructure by introducing the fracture toughness of the compacts. The mean fragment size is calculated using a modified form of Mott's theory and successfully compared with experimental results.The authors gratefully acknowledge financial support provided by ONR/MURI Grant No. N00014-07-1-0740 (Program Officer Dr. Clifford Bedford). We acknowledge Prof. V. F. Nesterenko for the use of the high speed camera. Discussions with Dr. S. Walley at Cavendish Laboratory are gratefully acknowledged.This is the author accepted manuscript. It is currently under an indefinite embargo pending publication by AIP Publishing

Synthesis by extrusion: continuous, large-scale preparation of MOFs using little or no solvent

YesGrinding solid reagents under solvent-free or low-solvent conditions (mechanochemistry) is emerging as a general synthetic technique which is an alternative to conventional solvent-intensive methods. However, it is essential to find ways to scale-up this type of synthesis if its promise of cleaner manufacturing is to be realised. Here, we demonstrate the use of twin screw and single screw extruders for the continuous synthesis of various metal complexes, including Ni(salen), Ni(NCS)2(PPh3)2 as well as the commercially important metal organic frameworks (MOFs) Cu3(BTC)2 (HKUST-1), Zn(2-methylimidazolate)2 (ZIF-8, MAF-4) and Al(fumarate)(OH). Notably, Al(fumarate)(OH) has not previously been synthesised mechanochemically. Quantitative conversions occur to give products at kg h−1 rates which, after activation, exhibit surface areas and pore volumes equivalent to those of materials produced by conventional solvent-based methods. Some reactions can be performed either under completely solvent-free conditions whereas others require the addition of small amounts of solvent (typically 3–4 mol equivalents). Continuous neat melt phase synthesis is also successfully demonstrated by both twin screw and single screw extrusion for ZIF-8. The latter technique provided ZIF-8 at 4 kg h−1. The space time yields (STYs) for these methods of up to 144 × 103 kg per m3 per day are orders of magnitude greater than STYs for other methods of making MOFs. Extrusion methods clearly enable scaling of mechanochemical and melt phase synthesis under solvent-free or low-solvent conditions, and may also be applied in synthesis more generally.EPSRC (EP/L019655/1

Synthesis by wet chemistry and characterization of LiNbO3 nanoparticles

Actually, lithium niobate (LiNbO3) has been used for optical wavelength conversion and ultrafast optical signal processing because of its outstanding rapid nonlinear optical response behavior, low switching power and broad conversion bandwidth. LiNbO3nanoparticles, which belong to the ferroelectric oxide class, were synthesized by chemical reaction with wetchemistry. Their sizedistributionwascenteredaround200 nm. Xray diffraction (XRD) and scanning electron microscopy (SEM) were used to further investigate the quality of the obtained LiNbO3powders.The present work shows thatby employingthis chemical method the correct stoichiometric phasewas obtained. This wascorroborated by XPS (X-Ray Photoelectron Spectroscopy) results. Also, the nanoparticles showed a defined crystallinity and uniform morphology. This way of obtaining nanoparticles is innovative because of its low cost and simple way to reproduce it. It isan important method of increasing the surfacearea, controlling thephase purityand reducing theparticle size distribution. The samples were obtained under low temperature annealing at500, 650 and 800 ºC. Those features can be controlled using variables such temperature, time of synthesis,and calcination. In previous worksit wasfound that hydrothermal methods offer many advantages over conventional ceramic synthesis methods

Discovery of protein–DNA interactions by penalized multivariate regression

Discovering which regulatory proteins, especially transcription factors (TFs), are active under certain experimental conditions and identifying the corresponding binding motifs is essential for understanding the regulatory circuits that control cellular programs. The experimental methods used for this purpose are laborious. Computational methods have been proven extremely effective in identifying TF-binding motifs (TFBMs). In this article, we propose a novel computational method called MotifExpress for discovering active TFBMs. Unlike existing methods, which either use only DNA sequence information or integrate sequence information with a single-sample measurement of gene expression, MotifExpress integrates DNA sequence information with gene expression measured in multiple samples. By selecting TFBMs that are significantly associated with gene expression, we can identify active TFBMs under specific experimental conditions and thus provide clues for the construction of regulatory networks. Compared with existing methods, MotifExpress substantially reduces the number of spurious results. Statistically, MotifExpress uses a penalized multivariate regression approach with a composite absolute penalty, which is highly stable and can effectively find the globally optimal set of active motifs. We demonstrate the excellent performance of MotifExpress by applying it to synthetic data and real examples of Saccharomyces cerevisiae. MotifExpress is available at http://www.stat.illinois.edu/~pingma/MotifExpress.htm