Improving microbiological food Safety in peri-urban Mali; an experimental study

IntroductionTwenty years ago, a WHO review of the literature assumed that most food-borne disease transmission in developing countries takes place within the home, and advocated a major programme of interdisciplinary research to develop and test cost-effective interventions to promote food hygiene.MethodsThe HACCP approach was applied step by step, to two selected weaning foods prepared by 15 volunteer mothers in peri-urban Mali. After setting Critical Control Points (CCP), actions were taken to control, reduce or eliminate microbial growth at these points. 432 food samples were collected and examined for thermotolerant coliforms in a local laboratory to assess the effectiveness of the approach. Lessons learnt were translated into messages delivered in a pilot study.ResultsTraditional cooking was very effective in eliminating faecal contamination; reheating was as effective as cooking when adopted, because there was no significant difference in the temperatures reached in both cases. Behavioural corrective actions were effective in controlling faecal contamination at the other CCPs (serving the child after cooking and after reheating).ConclusionIn conclusion, the HACCP experiment improved significantly the bacterial safety of both types of weaning food studied.     

The determination of volume ratios by gas depletion through multiple expansions

We present a new technique for the determination of the volume ratio of two vacuum chambers connected through a valve. The method is based on the measurement of the pressure in a chamber filled with a gas that is repeatedly depleted by expansion in a second chamber that was previously evacuated. Our calculation shows that under the reported measurement conditions, this technique has an uncertainty comparable to that obtained from the gas accumulation technique [Elliott KWT, Clapham PB.The accurate measurement of the volume ratios of vacuum vessels. NPL Report MOM 28, January 1978]. An excellent equivalence between the results obtained with this new technique and the measurements obtained by the gas accumulation technique is demonstrated.     

Insight into spontaneous recurrent calcium waves in a 3-D cardiac cell based on analysis of a 1-D deterministic model

Calcium dynamics in a cardiac cell are described by a system of 3-D non-linear stochastic partial differential equations. To obtain solutions that have biophysical properties, it is necessary to explore the model parameter space. To decrease the complexity of the parameter search, we reduce the 3-D stochastic model to a 1-D deterministic model. The reduction of the problem from 3-D to 1-D is done through an asymptotic approximation after non-dimensionalization and based on rational biophysical assumptions of the 3-D domain; the stochastic to deterministic transformation is based on the regular property of the 3-D solution. The result of the model reduction proves very effective in reducing the time required to get qualitative as well as quantitative information about parameter regions in the 3-D stochastic model including calcium dynamics (sparks, wave propagation, and recovery) observed in cardiac cells.     

Fabrication of high-aspect ratio Si pillars for atom probe ‘lift-out’ and field ionization tips

A process for fabricating high-aspect ratio (∼1:20), micron-sized Si [0 0 1] pillars using mechanical and chemical size reduction is presented. A dicing saw was used for mechanically patterning an array of square pillars with side lengths of >20 μm. These pillars were then reduced in size using an aqueous NaOH and KOH solution heated to 100 °C. The chemical etch reduces the pillar size within the time range amenable for focus ion beam milling and/or attachment for atom probe ‘lift-out’ specimens. The pillars can be formed with either a flat top surface or into <100 nm tip points for direct field ionization.     

Investigation of the impact response of PMMA-based nano-rubbers under various temperatures

To benefit from nano-rubber copolymers, the properties and dynamic behavior of nano-rubbers reinforced Poly(Methyl Methacrylate) (PMMA) were investigated. Dynamic tests were conducted on these materials at high strain rates and different temperatures using split Hopkinson pressure bars. The impact resistance of these materials was studied by performing low velocity impact tests with a drop weight tower at different impact energies and temperatures. The results showed decreased Young’s moduli and yield stresses. The mechanical behavior of the materials exhibited strain rate and temperature dependencies. Moreover, the nano-rubber-reinforced PMMA showed outstanding impact resistance compared with neat PMMA. The modified PMMA also exhibited impact properties similar to those of polycarbonate for certain ranges of impact energies and temperatures. No perforations were observed for all those energies and temperatures.     

Hybrid offset‐time and burst assembly algorithm (H‐OTBA) for delay sensitive applications over optical burst switching networks

Optical burst switching (OBS) is the most favourable switching paradigm for future all‐optical networks. Burst assembly is the first process in OBS and it consists of aggregating clients packets into bursts. Assembled bursts wait for an offset time before being transmitted to their intended destinations. Offset time is used to allow burst control packet reserve required resources prior to burst arrival. Burst assembly process and offset‐time create extra delay in OBS networks. To make OBS suitable for real time applications, this extra latency needs to be controlled. This paper proposes and evaluates a novel offset time and burst assembly scheme to address this issue. Constant bit rate (CBR) traffic that has stringent end‐to‐end delay QoS requirements is used in this study. The proposed scheme is called hybrid offset‐time and burst assembly algorithm (H‐OTBA). The objective of the paper is achieved by controlling maximum burst transfer delay parameters of CBR. The proposed scheme was evaluated via network simulation. Simulation results demonstrate that, H‐OTBA has effectively reduced end‐to‐end delay for CBR traffic compared with current solutions. Copyright © 2014 John Wiley & Sons, Ltd.     

Eco Insulation Materials： Reduction of Cooling Loads of a House Made of Breeze Block or Laterite in a Dry Tropical Climate

In this paper, we study the influence ofeco materials for roof insulation and fiber-reinforced mortar coatings on cooling loads of a home in dry tropical climate. The walls of the house are made of cinderblock or laterite and the insulating material of a roof panel is made with lime （24%）, cement （6%）, water （50%） of vegetable fibers hibiscus sabdariffa （16%）, tree widespread in Burkina Faso and sugar cane bagasse （4%）. This panel roof insulation and the fiber-reinforced mortar were characterized at the Laboratory of Physics and Chemistry of the environment by the hot plate method. The building is modeled in TRNSYS using climate data from the city of Ouagadougou. The results obtained show that in the warmer months of the year, that is to say in March and April, the relative differences between heat gains the configurations ＂breeze block-coating mortar and roof not insulated＂ and ＂laterite- fiber-reinforced mortar coating and insulated roof＇ vary between 15.6% and 16.8%. The configuration ＂laterite-fiber-reinforced mortar coating and insulated roof allows a reduction of annual heat gains of 15.5% compared to the configuration ＂breeze block-coating mortar and roof not insulated＂.     

The concentrations of IL-8 and IL-6 in gingival crevicular fluid during nickel–chromium alloy porcelain crown restoration

We explored gum irritation and cytotoxicity caused by nickel–chromium (Ni–Cr) alloy porcelain by interleukin-8 (IL-8), interleukin-6 (IL-6) and gingival crevicular fluid (GCF) volumes at different time points peri-crown restoration. This prospective study was conducted in 60 young adults. The total amount and concentrations of IL-8 and IL-6 per site, GCF volumes, and blood neutrophil counts were performed prior to and at 1 week, 3 months, and 6 months after Ni–Cr alloy-porcelain crown restoration. Thirty male and 30 female subjects, aged 20–35 years old were enrolled. The total amount and concentrations of IL-8 and IL-6 per site, GCF volumes increased after nickel–chromium (Ni–Cr) alloy-porcelain crown restoration, and reached its peak at the third month as the GCF volume increased by 52.20 %, the total amount and concentrations of IL-8 increased by 112.11 and 22.75 %; the total amount and concentrations of IL-6 increased by 77.66 and 17.17 % when compared to baseline. In particular, the increase of IL-8 concentration was found in female patients at 3 months after restoration; while the neutrophil count of the peripheral blood did not change significantly. The increase in the total amount and the concentrations of IL-8 and IL-6 and GCF volume may be related to the cytotoxicity induced by Ni–Cr alloy. The significant increase of IL-8 concentration in females indicates that more attention should be given to women during Ni–Cr alloy porcelain crown restoration.