Toughness in synthetic and biological multilayered systems

Toughness in hard biological tissues is associated with fibrous or lamellar structures that deflect or stop growing cracks. In some cases, such as nacreous shell, protein interlayers absorb much of the crack energy. In other tissues, such as tooth enamel, the toughness derives from the mineral microstructure, and the small amount of residual protein apparently has little effect. There have been a number of efforts to make tough synthetic materials using layered structures. In this work, freeform fabrication has been used to make layered structures with a view to introducing similar toughness into brittle materials. Results are presented for epoxy-glass composites with glass fabric interlayers, porous alumina back-filled with aluminium metal, and layered glass-ceramic/silver materials.     

Truck sizing models for recyclables pick-up

Growing public concerns about the environmental consequences of waste disposal have led to an increase in recycling efforts. In many communities, curbside collection programs have been instituted for collecting recyclables from households for transfer to material recovery facilities. In most programs the cost of collection is the dominant cost. Despite the high cost and environmental importance of collecting recyclables from households, most municipal collection systems are designed and operated without a clear understanding of what factors drive those costs and how they might be reduced. In this paper, models for determining truck configurations, as well as optimal compartment sizes for recyclables collection are developed. Constraints arising from the operation of the trucks are formulated, and solution schemes are presented. In addition, a procedure for optimally partitioning a vehicle used to collect source-separated material is discussed. Several scenario based planning approaches are developed. Use of the truck sizing models as an industry decision tool and the associated benefits of applying the truck sizing models and the solution methodology to a contract based collection program are also discussed.     

Metabolism of monoterpene alcohol, linalool, by a soil pseudomonad

A microorganism of the genus Pseudomonas has been isolated from the soil by enrichment culture techniques with linalool(I) as the sole source of carbon and energy. The organism is also capable of utilizing limonene, citronellol, and geraniol as substrates but fails to grow on citral, critranellal, and 1,8-cineole. Fermentation of linalool by this bacterium in a mineral salt medium results in the formation of 10-hydroxylinalool(II), oleuropeic acid (IX), 2-vinyl-2-methyl-5-hydroxyisopropyl-tetraphydrofuran)linalool oxide, V), 2-vinyl-2-methyl-tetrahydrofuran-5-one(unsaturated lactone, VI), and few unidentified minor metabolities. Probable pathways for the biodegradation of linalool are presented.     

Involvement of 4-hydroxymandelic acid in the degradation of mandelic acid by Pseudomonas convexa

A microorganism capable of degrading DL-mandelic acid was isolated from sewage sediment of enrichment culture and was identified as Pseudomonas convexa. It was found to metabolize mandelic acid by a new pathway involving 4-hydroxymandelic acid, 4-hydroxybenzaldehyde, 4-hydroxybenzoic acid, and 3,4-dihydroxybenzoic acid as aromatic intermediates. All the enzymes of the pathway were demonstrated in cell-free extracts. L-Mandelate-4-hydroxylase, a soluble enzyme, requires tetrahydropteridine, nicotinamide adenine dinucleotide phosphate, reduced form, and Fe2+ for its activity. The next enzyme, L-4-hydroxymandelate oxidase (decarboxylating), a particulate enzyme, requires flavine adenine dinucleotide and Mn2+ for its activity. A nicotinamide adenine dinucleotide-dependent, as well as a nicotinamide adenine dinucleotide phosphate-dependent, benzaldehyde dehydrogenase has been resolved and partially purified.     

Selective detection of proteins in mixtures using electrospray ionization mass spectrometry: influence of instrumental settings and implications for proteomics

We studied the effects of electrospray mass spectrometric instrumental settings on the relative and absolute detection of individual proteins in a five-component mixture. Conditions that were effective for a given protein could be very poor for the others, and vice versa, such that to a good approximation it was possible to find conditions for selective detection of individual proteins in a complex mixture without prior analytical separation. Some of these could be rationalized on the basis of the known biophysical properties of the individual proteins. The ability to vary the conditions of a mass spectrometric detection method on-line provides an important degree of freedom for the selective detection, and hence discrimination, of individual proteins and peptides in complex mixtures and has implications in proteomics, in particular with respect to top-down strategies for proteomic characterizations.     

Discrimination of aerobic endospore-forming bacteria via electrospray-lonization mass spectrometry of whole cell suspensions

Direct injection electrospray ionization mass spectrometry (ESI-MS) without prior analyte separation was investigated for the analysis of whole cell suspensions of bacteria. Thirty-six strains of aerobic endospore-forming bacteria, consisting of six Bacillus species and one Brevibacillus species, were studied     

Cellular convection in vertical annuli of fast breeder reactors

In the pool type fast reactors the roof structure is penetrated by a number of pumps and heat exchangers that are cylindrical in shape. Sandwiched between the free surface of sodium and the roof structure, is stagnant argon gas, which can flow in the annular space between the components and roof structure, as a thermosyphon. These thermosyphons not only transport heat from sodium to roof structure, but also result in cellular convection in vertical annuli resulting in circumferential temperature asymmetry of the penetrating components. There is need to know the temperature asymmetry as it can cause tilting of the components. Experiments were carried out in an annulus model to predict the circumferential temperature difference with and without sodium in the test vessel. Three-dimensional analysis was also carried out using PHOENICS CFD code and compared with the experiment. This paper describes the experimental details, the theoretical analysis and their comparison.     

Quadratically Constrained Beamforming Robust Against Direction-of-Arrival Mismatch

It is well known that the performance of the minimum variance distortionless response (MVDR) beamformer is very sensitive to steering vector mismatch. Such mismatches can occur as a result of direction-of-arrival (DOA) errors, local scattering, near-far spatial signature mismatch, waveform distortion, source spreading, imperfectly calibrated arrays and distorted antenna shape. In this paper, an adaptive beamformer that is robust against the DOA mismatch is proposed. This method imposes two quadratic constraints such that the magnitude responses of two steering vectors exceed unity. Then, a diagonal loading method is used to force the magnitude responses at the arrival angles between these two steering vectors to exceed unity. Therefore, this method can always force the gains at a desired range of angles to exceed a constant level while suppressing the interferences and noise. A closed-form solution to the proposed minimization problem is introduced, and the diagonal loading factor can be computed systematically by a proposed algorithm. Numerical examples show that this method has excellent signal-to-interference-plus-noise ratio performance and a complexity comparable to the standard MVDR beamformer.     

Amino‐functionalised mesoporous silica microspheres for immobilisation of Candida antarctica lipase B – application towards greener production of 2,5‐furandicarboxylic acid

In the present study, amino‐functionalised mesoporous silica microspheres were utilised as support for the covalent immobilisation of Candida antarctica lipase B (CaLB) for the subsequent production of 2,5‐furandicarboxylic acid (FDCA) from 2,5‐diformylfuran (DFF). Under the optimised operating conditions of pH 6.5, particle/enzyme ratio of 1.25:1.0 and glutaraldehyde concentration of 4 mM, a maximum CaLB immobilisation yield of 82.4% on silica microspheres was obtained in 12.25 h. The immobilised CaLB was used for the synthesis of alkyl esters, which were utilised along with hydrogen peroxide for FDCA synthesis. The biocatalytic conversion of 30 mM DFF dictated a 77–79% FDCA in 48 h at 30°C; where the turnover number and turnover frequency of immobilised CaLB were 6220.73 mol mol⁻¹ and 129.59 h⁻¹, respectively, for ethyl acetate, against 6297.65 mol mol⁻¹ and 131.2 h⁻¹, respectively, for ethyl butyrate. Upon examining the operational stability, the immobilised CaLB exhibited high stability till five cycles of FDCA production.Inspec keywords: mesoporous materials, organic compounds, biotechnology, silicon compounds, renewable materials, catalysis, catalysts, enzymes, thermal stability, biofuelOther keywords: FDCA production, amino‐functionalised mesoporous silica microspheres, greener production, 2,5‐furandicarboxylic acid, covalent immobilisation, 2,5‐diformylfuran, CaLB immobilisation, Candida antarctica lipase B immobilisation, ethyl butyrate, time 48.0 hour, temperature 30.0 degC, time 12.25 hour