Improvement of Injera shelf life through the use of chemical preservatives

Mould spoilage is a serious problem that affects the shelf life of injera, the staple Ethiopian fermented bread. Injera is made from teff (Eragrostis tef) but other cereals may also be used in combination with teff. About two-third of Ethiopian diet consists of injera and it accounts for about two-thirds of the daily protein intake of the Ethiopian population. Injera has a high nutritional value, as it is rich in calcium and iron. Unfortunately, injera has a shelf life of only 3-4 days essentially due to mould spoilage. The use of weak organic acid as preservative is allowed in acidic foods,primarily as mould inhibitors. In this study, the effect of chemical preservatives such as benzoic acid, sodium benzoate, potassium sorbate and calcium propionate were investigated to prolong shelf life of injera. The preservatives were added immediately before baking at the concentration of 0.1% of benzoic acid, 0.1% sodium benzoate, 0.2% of potassium sorbate, 0.3% of calcium propionate and 0.2% blend of the four as recommended by Food and Drug Administration of USA. Three fungal species: Aspergillus niger, Penicillium sp and Rhizopus sp were found to be responsible for injera spoilage. Penicillium and Rhizopus were more dominant at storage temperature of between 16-200C, while Aspergillus niger was found to be more dominant at higher temperature of 25-320C. Injera samples had a pH and moisture content between 3.38- 3.45 and 62-65%, respectively. Anti-fungal activities of the preservatives investigated significantly prolonged the shelf life of injera for up to12 days. It was found out that the effectiveness of preservation was ranked as sodium benzoate>benzoic acid>potassium sorbate>blend>calcium propionate showing that benzoate and benzoic acid are the most effective. The outcome of the research has a significant implication in food security, energy utilization and a significant reduction in the amount of time used by women to produce injera

Artemisia annua l. As an alternative potential weed control option

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Weblog patterns and human dynamics with decreasing interest

Weblog is the fourth way of network exchange after Email, BBS and MSN. Most bloggers begin to write blogs with great interest, and then their interests gradually achieve a balance with the passage of time. In order to describe the phenomenon that people's interest in something gradually decreases until it reaches a balance, we first propose the model that describes the attenuation of interest and reflects the fact that people's interest becomes more stable after a long time. We give a rigorous analysis on this model by non-homogeneous Poisson processes. Our analysis indicates that the interval distribution of arrival-time is a mixed distribution with exponential and power-law feature, that is, it is a power law with an exponential cutoff. Second, we collect blogs in ScienceNet.cn and carry on empirical studies on the interarrival time distribution. The empirical results agree well with the analytical result, obeying a special power law with the exponential cutoff, that is, a special kind of Gamma distribution. These empirical results verify the model, providing an evidence for a new class of phenomena in human dynamics. In human dynamics there are other distributions, besides power-law distributions. These findings demonstrate the variety of human behavior dynamics.Comment: 8 pages, 1 figure

Carleson Measures and Toeplitz Operators

In this last chapter we shall describe an application of the Kobayashi distance to geometric function theory and functional analysis of holomorphic functions

An Axiomatic Approach to Liveness for Differential Equations

This paper presents an approach for deductive liveness verification for ordinary differential equations (ODEs) with differential dynamic logic. Numerous subtleties complicate the generalization of well-known discrete liveness verification techniques, such as loop variants, to the continuous setting. For example, ODE solutions may blow up in finite time or their progress towards the goal may converge to zero. Our approach handles these subtleties by successively refining ODE liveness properties using ODE invariance properties which have a well-understood deductive proof theory. This approach is widely applicable: we survey several liveness arguments in the literature and derive them all as special instances of our axiomatic refinement approach. We also correct several soundness errors in the surveyed arguments, which further highlights the subtlety of ODE liveness reasoning and the utility of our deductive approach. The library of common refinement steps identified through our approach enables both the sound development and justification of new ODE liveness proof rules from our axioms.Comment: FM 2019: 23rd International Symposium on Formal Methods, Porto, Portugal, October 9-11, 201

Challenges in tin perovskite solar cells

Perovskite solar cells are the rising star of third generation photovoltaic technology. With a power conversion efficiency of 25.5 , the record efficiency is close to the theoretical maximum efficiency of a single junction solar cell. However, lead toxicity threatens commercialization efforts and market accessibility. In this context, Sn based perovskites are a safe alternative. Nevertheless, the efficiency of Sn based devices falls far behind the efficiency of Pb based counterparts. This concise review sheds light on the challenges that the field faces toward making Sn based perovskites the perovskite photovoltaic benchmark. We identified four key challenges materials and solvents, film formation, Sn II oxidation, and energy band alignment. We illustrate every single challenge and highlight the most successful attempts to overcome them. Finally, we provide our opinion on the most promising trends of this field in the futur

Dynamics of an Intruder in Dense Granular Fluids

We investigate the dynamics of an intruder pulled by a constant force in a dense two-dimensional granular fluid by means of event-driven molecular dynamics simulations. In a first step, we show how a propagating momentum front develops and compactifies the system when reflected by the boundaries. To be closer to recent experiments \cite{candelier2010journey,candelier2009creep}, we then add a frictional force acting on each particle, proportional to the particle's velocity. We show how to implement frictional motion in an event-driven simulation. This allows us to carry out extensive numerical simulations aiming at the dependence of the intruder's velocity on packing fraction and pulling force. We identify a linear relation for small and a nonlinear regime for high pulling forces and investigate the dependence of these regimes on granular temperature

Tyrosinase expression in the peripheral blood of stage III melanoma patients is associated with a poor prognosis: a clinical follow-up study of 110 patients

The aim of this study is to define the relationship between the tyrosinase expression in the peripheral blood and the clinical course of the disease in stage III disease-free melanoma patients after radical lymph node dissection. RT-PCR techniques were used to identify tyrosinase mRNA in 110 patients; a total of 542 blood samples were investigated. In all, 54 patients (49%) showed at least one positive result; 13 patients (11.8%) showed baseline positive results: six became negative thereafter, whereas seven showed follow-up positive results until disease progression occurred. One or more positive determinations were found during follow-up in 41 patients with negative baseline tyrosinase. No correlation was found between baseline results and the relapse rate or disease-free survival (DFS), whereas a significant correlation was found between positive tyrosinase results and disease recurrence during follow-up. In fact, 72.9% of positive patients relapsed, but only 19.3% of negative cases did so. The median interval between the positive results and the clinical demonstration of the relapse was 1.9 months (range 1-6.6). Disease-free survival multivariate analysis selected, as independent variables, Breslow thickness (P=0.05), lymph node involvement according to the AJCC classification (P=0.05) and tyrosinase expression (P=0.0001). In conclusion, RT-PCR tyrosinase mRNA expression is a reliable and reproducible marker associated with a high risk of melanoma progression and we encourage its clinical use in routine follow-up