Multivariate Analysis of the Stability of Spray-Dried Eupenicillium javanicum Peptidases

Peptidases occupy a central position in the enzyme market because of their importance in many areas, such as for physiological processes, foods, and detergents, as well as in the pharmaceutical, leather, and biotechnology industries. Microbial production is among the major sources of peptidases because it presents many advantages when compared with other methods. In this study, the metallopeptidases produced by the fungus Eupenicillium javanicum under a solid-state fermentation bioprocess were spray-dried. The enzymatic extract was dried using drying adjuvants, and optimal conditions for preserving enzymatic activity were studied following a Box-Behnken experimental design. The spray process factors studied were the air-drying temperature, enzyme feed flow rate, and the proportion of enzyme/additive. The responses analyzed were the dry extract yield and enzymatic activity after spray drying. Additionally, the stability of the dry extracts was assessed during 180 days at 4°C and 25°C. The results revealed extract yields of up to 66.12% and good enzymatic activity for intermediate values of temperature and adjuvant proportions. Furthermore, the dried enzymatic extracts showed potential for future commercial applications because of their stability at 25°C for 180 days.     

Physicochemical characterization of sahti,an ‘ancient’ beer style indigenous to Finland

Sahti, a strong, unhopped farmhouse beer flavoured with juniper, is still actively brewed in rural areas in Finland. Presented here is the first comprehensive analysis of the physical and chemical properties of this unique beer style. Twelve sahti samples from the southwest of Finland were analysed and, while properties varied, the beers generally had high levels of alcohol (mean = 7.9% ABV) and high residual extract (mean = 9.5°P). Foam stability was negligible, as is typical for the style, and glycerol concentrations at 3.1 – 4.7 g L^?1 were higher than in reference beers (commercial lager, wheat beer and porter). These features may be attributed to the very high gravity conditions employed in brewing sahti beers. Bitterness levels were relatively low (3–13 IBU) owing to the absence or moderate use of hops. All samples contained detectable levels of the clove‐like compound 4‐vinylguaiacol owing to the use of baker's rather than brewer's yeast for brewing. Concentrations of higher alcohols and esters were high, with many individual aroma compounds being above the normal flavour thresholds. Results have highlighted the uniqueness of this style of beer in comparison to commercially available beers and have contributed to our understanding of the reasons for the particular sensorial properties of this traditional beer style. Copyright © 2015 The Institute of Brewing & Distilling     

An upper bound for the distance between a zero and a critical point of a solution of a second order linear differential equation

This paper presents an upper bound for the distance between a zero and a critical point of a solution of the second order linear differential equation (p(x)y^′)^′+q(x)y(x)=0, with p(x),q(x)>0. It also compares it with previous results.     

Polymerisation of styrene using Y, USY and β zeolites as catalysts

The homopolymerisation of styrene is studied in the presence of Y, USY and beta zeolites. High molecular weight polymers, in the range 0.7 × 10⁶–1 × 10⁶, are obtained in good yields. The activity of zeolite beta is only slightly increased by calcination of the as-synthesised material, pointing to an important role of the zeolite outer surface. The influence of the catalyst acidity upon the polymer molecular weight is evaluated by the use of dealuminated zeolites. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis of polar vinyl monomer–olefin copolymers by α‐diimine nickel catalyst

Vinyl acetate, methyl methacrylate, acrylonitrile and methyl vinyl ketone were investigated for co‐ and terpolymerization with ethylene and ethylene–propylene. Precursor [bis(N,N ′‐dimesitylimino)acenaphthene]dibromonickel, activated by methylaluminoxane was used as a catalyst system and trialkylaluminium was employed to block the polar groups for these polymerizations. Polymerization activities of the order of magnitude of 10⁶ in the case of vinyl acetate and methyl methacrylate, and 10⁵ in the case of acrylonitrile were achieved. Microanalysis and GPC of acrylonitrile copolymers found about 17 units of acrylonitrile per polymer chain. Copolymers with very different properties from the parent homopolymers were obtained in all cases except that of methyl vinyl ketone. © 2001 Society of Chemical Industry     

Performance Evaluation of a Zero-Fouling Reciprocating Scraped-Surface Heat Exchanger

An innovative self-cleaning shell-and-tube heat exchanger is presented. Inside each interior tube (through which the product flows) a scraping rod is fitted. This rod moves in reciprocal manner and the scraping elements mounted on the rod fully clean the tube wall surface. Additionally, the macroscopic displacements of the flow, induced by the insert device motion, promote high flow mixing. Consequently, tube-side heat transfer coefficients are enhanced. Thermal-hydraulic and scraping power measurements are performed in laminar regime for motionless and dynamic conditions. An extended performance evaluation criterion is proposed, in order to balance the augmentation of heat transfer and the increased power consumption (pumping and scraping power) of the device. This study allows stating guidelines for the operation of the device, concluding that the performance of the heat exchanger is irrespective of the velocity ratio. The scraper can be used intermittently, or at the minimum scraping frequency that ensures fouling mitigation.     

Evaluation of combined heat and power (CHP) systems performance with dual power generation units for different building configurations

This paper evaluates the economic, energetic, and environmental feasibility of using two power generation units (PGUs) to operate a combined heat and power (CHP) system. Several benchmark buildings developed by the Department of Energy simulated using the weather data for Chicago, IL, are used to analyze the proposed configuration. This location has been selected because it usually provides favorable CHP system conditions in terms of cost and emission reduction. For the proposed configuration, one PGU is operated at base load to satisfy part of the electricity building requirements, whereas the other is used to satisfy the remaining electricity requirement operating following the electric load. The dual‐PGU CHP configuration (D‐CHP) is modeled for four different scenarios to determine the optimum operating range for the selected benchmark buildings. The dual‐PGU scenario is compared with the reference building using conventional technology to determine the benefits of this proposed system in terms of operational cost, primary energy reduction, and carbon dioxide emissions. The D‐CHP system results are also compared with a CHP system operating following the electric load (FEL) and base‐loaded CHP system. For three of the selected buildings, the proposed D‐CHP system provides comparable or greater savings in operating cost, primary energy consumption, and carbon dioxide emissions than the optimized conditions for base loading and FEL. In addition, the effect of operating the D‐CHP system only during certain months of the year on the overall operational cost is also evaluated. Results indicate that not operating the D‐CHP system for the months where the thermal load is too low is beneficial for the overall system performance. Copyright © 2012 John Wiley & Sons, Ltd.     

The role of Smart Grids to foster energy efficiency

The traditional electricity grid has remained the same for most of last century, without major architectural improvements. However, its requirements, guidelines and goals do have changed, especially during the last few years, driven by the sustainability in energy generation and energy efficiency principles. Thus, taking greenhouse gases emissions and CO₂ footprint reduction as key objectives and information and communications technologies as key enabler technologies, a novel and revolutionary electric grid paradigm, the so-called Smart Grid, is emerging, in which energy efficiency and renewable generation play a central role. This paper presents an overview on the main requirements and features of Smart Grids to integrate energy efficiency, on the work done and to be done, on the enabler technologies, as well as on the expected impacts and the main benefits Smart Grids will bring.     

Revisiting the weighting function for lightness in the CIEDE2000 colour-difference formula

We have used 13 experimental datasets (7420 colour pairs) to study the performance of the weighting function for lightness proposed by the CIEDE2000 colour-difference formula, because it has been suggested that this function can be improved by using the weighting function for lightness S_L = 1 adopted by the CIE94 colour-difference formula. Using the standardised residual sum of squares (STRESS) index, it was found that: (i) replacing the S_L in CIEDE2000 with S_L = 1 improved the results for 7/13 datasets considered, but the improvement was statistically significant only for 1/13 datasets; (ii) a Whittle-type lightness-difference formula can be used to replace the term ∆L*/S_L in CIEDE2000, which led to a new colour-difference formula with no statistically significant difference with respect to CIEDE2000 for any of the 13 experimental datasets. A modification of the CIEDE2000 formula using a Whittle-type lightness formula is proposed.