Stepwise optimisation of enzyme production in solid state fermentation of waste bread pieces

When it is not consumed, bread presents a major source of food waste, both in terms of the amount and its economic value. However, bread also possesses the characteristics of an ideal substrate for solid state fermentation. Yet nearly all wasted bread ends up in landfill sites, where it is converted into methane by anaerobic digestion. Governments are finally taking action and, according to the EU Landfill Directive, for example, biodegradable municipal waste disposed into landfills must be decreased to 35% of 1995 levels, by 2020. Solid state fermentation of waste bread for the production of value added products is a novel idea, which could help with the achievement of this target. In this study, glucoamylase and protease production from waste bread pieces, via solid state fermentation, was investigated in detail. The optimum fermentation conditions for enzyme production were evaluated as, 20 mm particle size, 1.8 (w/w, db) initial moisture ratio, and duration of 144 h. Under these conditions, glucoamylase and protease activities reached up to 114.0 and 83.2 U/g bread (db), respectively. This study confirms that waste bread could be successfully utilised as a primary raw material in cereal based biorefineries.     

Influence of intracrystalline diffusion in shape selective catalytic test reactions

Molecular dynamics simulations are used to measure the self diffusion constant D of linear decane and n-methylnonanes (n = 2, 3, 4, and 5) at a catalytically relevant temperature in seven 10 member ring zeolites. Two general behaviors are observed in D as the branch position is moved towards the center of the alkane chain. For three of the zeolites (MEL, MFI, and MTT), D decreases monotonically as expected based on a consideration of the bulkiness of the different isomers. For the other four, alkane diffusion is considered anamolous as D is not a monotonic function of branch position. For n-methylnonanes in three zeolites D shows a minimum at either n = 2 (FER), 3 (EUO), or 4 (TON). In AEL, D has a local maximum for n = 3. Alkane diffusion is anamolous in these zeolites because they have structural features that provide a unique hindrance to molecular motion along the main diffusion channel. The ability of the zeolite to hinder motion depends on the molecular structure of the isoparaffin, resulting in the anamolous behavior observed. The 10 member ring zeolites selected for this study represent the entire group for which known structures exist and values of the modified constraint index have been published. The diffusion data presented indicates that product shape selectivity may play some part in determining the modified constraint index. This revised version was published online in July 2006 with corrections to the Cover Date.     

Video-rate confocal scanning laser microscope for imaging human tissues in vivo

We have built a video-rate confocal scanning laser microscope for reflectance imaging of human skin and oral mucosa in vivo. Design and imaging parameters were determined for optimum resolution and contrast. Mechanical skin-holding fixtures and oral tissue clamps were made for stable objective lens-to-tissue contact such that gross tissue motion relative to the microscope was minimized. Confocal imaging was possible to maximum depths of 350 mum in human skin and 450 mum in oral mucosa, with measured lateral resolution of 0.5-1 mum and axial resolution (section thickness) of 3-5 mum at the 1064-nm wavelength. This resolution is comparable with that of conventional microscopy of excised biopsies (histology). Normal and abnormal tissue morphology and dynamic processes were observed.     

Scaling of GaAs/AlGaAs laser diodes for submilliampere threshold current

GaAs/AlGaAs lasers grown by a single-step MBE on grooved substrates have been used to investigate the scaling of lasers for very low threshold current. By tuning the facet reflectivity and the laser length, to keep the photon lifetime constant, it has been possible to scale down the threshold current to 0.65 mA without changing the external efficiency.<>     

Numerical solution of the continuous waveguide transition problem

A simple transition between two sizes of rectangular waveguide is analyzed using the generalized telegraphist's equation. Solutions are obtained using a new moment method technique, a Runge-Kutta algorithm, and an iterative numerical integration technique. The results are compared to previously published experimental and numerical data. It is found that the numerical stability, accuracy, and consistency of the results are critically dependent on the choice of weighting and expansion functions. The best results for a simple rectangular-to-rectangular transition were obtained when Galerkin's method and triangle expansion functions were applied to several short sections which were then cascaded. Unlike the Runge-Kutta technique or the integration technique, the Galerkin's method procedure did not result in instabilities with the inclusion of evanescent modes. The programs can, in fact, be extended to any number of modes, the only apparent limitations being the obvious ones of computer time and memory     

Neglected aspects and unsupported claims.

Comments on the article by M. E. Kite et al (see record 2001-10045-002), which summarized the findings and recommendations of the Task Force on the Status of Women in Academe. The present authors contend that while Kite et al documented the differences in the activities of men and women in academia, it is not clear that "inequalities persist." Kite et al interpreted the observed differences in outcomes between men and women as self-evident indicators of remaining bias and discrimination. The present authors warn of two problems with this interpretation. First, Kite et al neglected important variables that suggest alternative interpretations of these differences. Second, the authors made unsupported claims about the existence of bias and discrimination against women. Here the present authors document specific cases of these errors in reasoning. In conclusion, observed differences between men and women might be partly a reflection of other (neglected) personological variables on which the sexes overlap considerably but differ on average. Just as differential outcomes do not imply differential opportunities, equal opportunities do not necessarily produce equal outcomes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hierarchal vector basis functions of arbitrary order for triangularand tetrahedral finite elements

New vector finite elements are proposed for electromagnetics. The new elements are triangular or tetrahedral edge elements (tangential vector elements) of arbitrary polynomial order. They are hierarchal, so that different orders can be used together in the same mesh and p-adaption is possible. They provide separate representation of the gradient and rotational parts of the vector field. Explicit formulas are presented for generating the basis functions to arbitrary order. The basis functions can be used directly or after a further stage of partial orthogonalization to improve the matrix conditioning. Matrix assembly for the frequency-domain curl-curl equation is conveniently carried out by means of universal matrices. Application of the new elements to the solution of a parallel-plate waveguide problem demonstrates the expected convergence rate of the phase of the reflection coefficient, for tetrahedral elements to order 4. In particular, the full-order elements have only the same asymptotic convergence rate as elements with a reduced gradient space (such as the Whitney element). However, further tests reveal that the optimum balance of the gradient and rotational components is problem-dependent     

Auditing NT — Part 2

This second article on NT auditing focuses on controlling users: whether or not they use the system, what they can do once they are in, and how to keep a record of what they have done. As with the operating system configuration that we looked at in the last article, you will need administrator access to review many of the security settings, and to review the security log. You will also be using tools supplied in the NT Resource kit to get listings of information that cannot be effectively scanned online.     

An efficient algorithm for the incremental construction of a piecewise linear classifier

In this paper the problem of finding piecewise linear boundaries between sets is considered and is applied for solving supervised data classification problems. An algorithm for the computation of piecewise linear boundaries, consisting of two main steps, is proposed. In the first step sets are approximated by hyperboxes to find so-called “indeterminate” regions between sets. In the second step sets are separated inside these “indeterminate” regions by piecewise linear functions. These functions are computed incrementally starting with a linear function. Results of numerical experiments are reported. These results demonstrate that the new algorithm requires a reasonable training time and it produces consistently good test set accuracy on most data sets comparing with mainstream classifiers.