New sustainable approach to reduce cassava borne environmental waste and develop biodegradable materials for food packaging applications

This is a research article on transforming waste cassava into a sustainable resource that requires a new approach and redesign of the current processing methodologies.Transforming waste cassava into a sustainable resource requires a new approach and redesign of the current processing methodologies. Bitter cassava cultivars have been employed mainly as an emergency famine food, but could also be used as a value-added material for packaging. Processing of intact bitter cassava can minimize waste, and produce low-cost added value biopolymer packaging films for targeted applications. This study developed an improved simultaneous release, recovery and cyanogenesis (SRRC) downstream processing methodology for sustainable reduction of waste and development of film packaging material using intact bitter cassava. SRRC approach produced peeled (BP) and intact (BI) bitter cassava biopolymer derivatives. BI showed significantly higher yields ensuring 16% waste decrease with no environmental impact caused by discard residues. SRRC was very effective in reducing the total cyanogen content to within Codex minimum safety limits, demonstrating that the peeling of bitter cassava process can be avoided. Transparent films were produced using the casting method from both BP and BI derivatives. BI films were more transparent and homogeneous, less soluble, less permeable to moisture, less hydrophilic, more permeable to oxygen and carbon-dioxide, sealable, lower cost, than the BP. Hence, intact bitter cassava and SRRC can be used as sustainable, safe, integrative process solution for high value-added product (e.g., packaging film) production from low-cost biobased materials

Interaction of vortices in viscous planar flows

We consider the inviscid limit for the two-dimensional incompressible Navier-Stokes equation in the particular case where the initial flow is a finite collection of point vortices. We suppose that the initial positions and the circulations of the vortices do not depend on the viscosity parameter \nu, and we choose a time T > 0 such that the Helmholtz-Kirchhoff point vortex system is well-posed on the interval [0,T]. Under these assumptions, we prove that the solution of the Navier-Stokes equation converges, as \nu -> 0, to a superposition of Lamb-Oseen vortices whose centers evolve according to a viscous regularization of the point vortex system. Convergence holds uniformly in time, in a strong topology which allows to give an accurate description of the asymptotic profile of each individual vortex. In particular, we compute to leading order the deformations of the vortices due to mutual interactions. This allows to estimate the self-interactions, which play an important role in the convergence proof.Comment: 39 pages, 1 figur

Nonmonotonic inelastic tunneling spectra due to surface spin excitations in ferromagnetic junctions

The paper addresses inelastic spin-flip tunneling accompanied by surface spin excitations (magnons) in ferromagnetic junctions. The inelastic tunneling current is proportional to the magnon density of states which is energy-independent for the surface waves and, for this reason, cannot account for the bias-voltage dependence of the observed inelastic tunneling spectra. This paper shows that the bias-voltage dependence of the tunneling spectra can arise from the tunneling matrix elements of the electron-magnon interaction. These matrix elements are derived from the Coulomb exchange interaction using the itinerant-electron model of magnon-assisted tunneling. The results for the inelastic tunneling spectra, based on the nonequilibrium Green's function calculations, are presented for both parallel and antiparallel magnetizations in the ferromagnetic leads.Comment: 9 pages, 4 figures, version as publishe

Classical Evolution of Quantum Elliptic States

The hydrogen atom in weak external fields is a very accurate model for the multiphoton excitation of ultrastable high angular momentum Rydberg states, a process which classical mechanics describes with astonishing precision. In this paper we show that the simplest treatment of the intramanifold dynamics of a hydrogenic electron in external fields is based on the elliptic states of the hydrogen atom, i.e., the coherent states of SO(4), which is the dynamical symmetry group of the Kepler problem. Moreover, we also show that classical perturbation theory yields the {\it exact} evolution in time of these quantum states, and so we explain the surprising match between purely classical perturbative calculations and experiments. Finally, as a first application, we propose a fast method for the excitation of circular states; these are ultrastable hydrogenic eigenstates which have maximum total angular momentum and also maximum projection of the angular momentum along a fixed direction. %Comment: 8 Pages, 2 Figures. Accepted for publication in Phys. Rev.

Novel Intact Bitter Cassava: Sustainable Development and Desirability Optimisation of Packaging Films

This is a research article on novel biomaterials and optimal processing conditions are fundamental in low-cost packaging material production.Novel biomaterials and optimal processing conditions are fundamental in low-cost packaging material production. Recently, a novel biobased intact bitter cassava derivative was developed using an intrinsic, high-throughput downstream processing methodology (simultaneous release recovery cyanogenesis). Processing of intact bitter cassava can minimise waste and produce low-cost added value biopolymer packaging films. The objective of this study was to (i) develop and characterise intact bitter cassava biobased films and (ii) determine the optimal processing conditions, which define the most desirable film properties. Films were developed following a Box-Behnken design considering cassava (2, 3, 4 % w/v), glycerol (20, 30, 40 % w/w) and drying temperature (30, 40, 50 °C) and optimized using multi-response desirability. Processing conditions produced films with highly significant (p < 0.05) differences. Developed models predicted impact of processing conditions on film properties. Desirable film properties for food packaging were produced using the optimised processing conditions, 2 % w/v cassava, 40.0%w/w glycerol and 50 °C drying temperature. These processing conditions produced films with 0.3 %; transparency, 3.4 %; solubility, 21.8 %; water-vapour-permeability, 4.2 gmm/m2/day/kPa; glass transition, 56 °C; melting temperature, 212.6 °C; tensile strength, 16.3 MPa; elongation, 133.3 %; elastic modulus, 5.1MPa and puncture resistance, 57.9 J, which are adequate for packaging applications. Therefore, intact bitter cassava is a viable material to produce packaging films that can be tailored for specific sustainable, low-cost applications

Engineered food supplement excipients from bitter cassava for minimisation of cassava processing waste in environment

This is a research paper unchecked large-scale rudimentary upstream (submerged and solid-state fermentation processes of bitter cassava roots into alcohol have often contributed significantly to agricultural wastes in the environment.Unchecked large-scale rudimentary upstream (sub-merged and solid state) fermentation processes of bitter cas- sava roots into alcohol have often contributed significantly to agricultural wastes into environment. Thus, the study explored a proven valorisation methodology, Simultaneous Release Recovery Cyanogenesis (SRRC) along with intact bitter cassava polysaccharide-rich derivatives (CWF), as an apt to find alternative materials for food supplement excipients. Triplicate CWF powder, peeled or intact bitter cassava roots, were produced and analysed to determine crit- ical properties suitable in tablet making. Exclusion approach, using SRRC and compaction, was performed to select desired powder properties for tablet formulation. Microcrystalline cellulose, with known properties for developing drug excipients, was used as a validation reference material. Tablets, for disintegration time and in- vitro dissolution rates studies were produced using wet-granulation, and their potential to release and bio-avail Iron-Zinc investigated in-vitro (pHs 1.2 and 6.8 solutions, 37 0 C). Morphology and Iron-Zinc dissolution-release mechanisms were examined. Kinetic models were used to describe matrix dissolution and Iron-Zinc release mech- anisms. Intact root powder compaction capacity, depicted by hardness, was 4.3, 4.4 and 4.6 KG at 200, 500 and 700 MPa respectively. Scanning Electron Microscopy (SEM) showed Iron-Zinc inclusion altered tablet morphol- ogy. Efficient matrix dissolution and Iron and Zinc release were achieved, showing apex recovery efficiency (98%, 30–45 min). Fitted models well-explained dissolution and release mechanisms (mean R 2 = 0.95), demonstrating adequacy. SRRC-improved intact bitter cassava was confirmed as potential alternative excipient’s matrix for Iron and Zinc release and bioavailability. Thus, this approach is practical for indirect waste elimination, and can promote strategy for sustainable valorisation of agricultural wastes and alternative functional food supplements delivery system

Integrated process standardisation as a zero-based approach to bitter cassava waste elimination and widely-applicable industrial biomaterial derivatives

This is a research article on Integrated standardised methodology for biopolymer derivatives (BPD) production from novel intact bitter cassava was demonstrated by desirability optimisation of simultaneous release, recovery, cyanogenesis (SRRC) processIntegrated standardised methodology for biopolymer derivatives (BPD) production from novel intact bitter cassava was demonstrated by desirability optimisation of simultaneous release, recovery, cyanogenesis (SRRC) process. BPD were evaluated for yield and colour using buffer (0,2,4 % v/v), cassava waste solids (15,23,30 % w/w), and extraction time (4,7,10 minutes). Nearly all the root was transformed into BPD, with higher yield and colour in comparison to starch extrinsically processed. Maximum global desirability, predicted efficient material balance, buffer 4.0 %w/v, cassava waste solids 23 %w/w and extraction time, 10 minutes, producing BPD yield, 38.8 % wb Validation using buffer, 3.3% w/v, cassava waste solids, 30 % w/w and extraction time, 10 minutes, produced 40.7 % wb BPD. SEM, DSC, TGA, FTIR and moisture barrier analyses revealed a uniform microstructure and high thermal stability of BPD and film, thus demonstrating efficient performance of the standardised integrated methodology. Hence, processing intact cassava root as a standardised integrated methodology could be used to produce sustainable low cost BPD for a broad range of applications. Methodologies designed around standard integrated procedures, matching zero-based approach to contamination, are novel strategies, and if used effectively can eliminate cassava wastes and recover BPD resources as sustainable biomaterials

Representations of the Weyl Algebra in Quantum Geometry

The Weyl algebra A of continuous functions and exponentiated fluxes, introduced by Ashtekar, Lewandowski and others, in quantum geometry is studied. It is shown that, in the piecewise analytic category, every regular representation of A having a cyclic and diffeomorphism invariant vector, is already unitarily equivalent to the fundamental representation. Additional assumptions concern the dimension of the underlying analytic manifold (at least three), the finite wide triangulizability of surfaces in it to be used for the fluxes and the naturality of the action of diffeomorphisms -- but neither any domain properties of the represented Weyl operators nor the requirement that the diffeomorphisms act by pull-backs. For this, the general behaviour of C*-algebras generated by continuous functions and pull-backs of homeomorphisms, as well as the properties of stratified analytic diffeomorphisms are studied. Additionally, the paper includes also a short and direct proof of the irreducibility of A.Comment: 71 pages, 1 figure, LaTeX. Changes v2 to v3: previous results unchanged; some addings: inclusion of gauge transforms, several comments, Subsects. 1.5, 3.7, 3.8; comparison with LOST paper moved to Introduction; Def. 2.5 modified; some typos corrected; Refs. updated. Article now as accepted by Commun. Math. Phy

The ODD protocol for describing agent-based and other simulation models: A second update to improve clarity, replication, and structural realism

© 2020, University of Surrey. All rights reserved. The Overview, Design concepts and Details (ODD) protocol for describing Individual-and Agent-Based Models (ABMs) is now widely accepted and used to document such models in journal articles. As a standardized document for providing a consistent, logical and readable account of the structure and dynamics of ABMs, some research groups also find it useful as a workflow for model design. Even so, there are still limitations to ODD that obstruct its more widespread adoption. Such limitations are discussed and addressed in this paper: the limited availability of guidance on how to use ODD; the length of ODD documents; limitations of ODD for highly complex models; lack of sufficient details of many ODDs to enable reimplementation without access to the model code; and the lack of provision for sections in the document structure covering model design ratio-nale, the model’s underlying narrative, and the means by which the model’s fitness for purpose is evaluated. We document the steps we have taken to provide better guidance on: structuring complex ODDs and an ODD summary for inclusion in a journal article (with full details in supplementary material; Table 1); using ODD to point readers to relevant sections of the model code; update the document structure to include sections on model rationale and evaluation. We also further advocate the need for standard descriptions of simulation experiments and argue that ODD can in principle be used for any type of simulation model. Thereby ODD would provide a lingua franca for simulation modelling