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Listeria monocytogenes is a foodborne human pathogen responsible for severe listeriosis and poses a great threat to human health. Hence, controlling the growth of L. monocytogenes plays an important role in the prevention of food contamination. Listeria innocua is often studied experimentally as a substitute strain for L. monocytogenes. In order to better maintain the sensory properties and nutrients of foods and extend their shelf life, this study explored the antimicrobial effect and possible mechanism of high pressure processing (HPP) combined with lauroyl arginate ethyl ester hydrochloride (LAE) on L. innocua. The feasibility of applying the combined treatment as a preservative was also investigated in ham. The results showed that 12 mg/L LAE treatment for 60 minutes had a potent antimicrobial effect on L. innocua, achieving a bacterial reduction of 3.12 (lg (CFU/mL)). Under the combined action of HPP and LAE, the surface morphology of bacterial cells became more wrinkled and sunken, and intracellular contents leaked out, suggesting a severe change in cell membrane permeability. The combined treatment of HPP at 350 MPa for 5 min with 12 mg/L LAE reduced L. innocua count by 4.87 (lg (CFU/mL)), which was 3.25 and 3.54 (lg (CFU/mL)) higher than that achieved using HPP and LAE treatments alone, respectively, suggesting a synergistic antimicrobial effect. Such synergistic antimicrobial effect was also observed on ham inoculated with L. innocua. This study could provide a theoretical reference for controlling the contamination of foodborne pathogens in ready-to-eat meat products.

In response to nutrient limitation, Bacillus and Clostridium can form metabolically dormant spores, which are extremely resistant to a variety of environmental stresses. The ubiquitousness of spores in the environment makes it inevitable for them to enter the food processing chain. Once suitable conditions are available, spores will rapidly germinate to resume vegetative growth, thereby causing food spoilage. Since germination induces the loss of stress resistance in dormant spores, germination-inactivation strategy has been developed to mildly kill spores while maintaining food quality. Understanding the spore germination process of diverse bacterial species, the related signal transduction mechanism and the factors impacting the germination process are beneficial to develop efficient and precise strategies for inducing spore germination and raising the efficiency of inactivation, which is of great significance to the control of spores in foods. This review describes the mechanisms of the spore germination of Bacillus subtilis, Clostridium perfringens and C. difficile in terms of spore germination receptor activation and signal transduction. Moreover, inducers and inhibitors of spore germination of diverse bacterial species are also comprehensively summarized. This review provides a theoretical foundation for effectively controlling bacterial spores in foods and ensuring food quality.

As the complexities of automotive systems increase, designing a system is a difficult task that cannot be done manually. In this paper, we propose an algorithm for weight minimization of wires used for connecting electronic devices in a system. The wire routing problem is formulated as a Steiner tree problem with capacity constraints, and the location of a Steiner vertex is selected for adding a splice connecting more than two wires. Besides wire routing, wire sizing is also done to satisfy resistance constraints and minimize the total wiring weight. Experimental results show the effectiveness and efficiency of our algorithm. Copyright 2014 ACM.

The annual output of steelmaking slag has exceeded 150 million tons. Mass accumulations of slag damage the environment and hinder sustainable development. Preparing cementing materials in the powder form is a promising solution for the large-scale utilization of slag. Our study focused on the effects of MgO and P2O5 on the grindability, soundness, and cementitious activity of steelmaking slags. Experimental results showed that by increasing the P2O5 content in basic oxygen furnace slag from 0.5% to 3%, the free CaO content, grindability index, and early strength decreased from 6.82% to 5.35%, 0.78 to 0.72, and 29.3 MPa to 21.0 MPa, respectively, and the later strength increased from 42.8 MPa to 46.5 MPa. For electric arc furnace slag, the free CaO content, grindability index, and early and later strengths decreased from 4.0% to 1.9%, 0.75 to ~ 0.6, 29.5 MPa to 23.6 MPa, and 31.2 MPa to 27.5 MPa, respectively. The increase in the MgO content insignificantly influenced the grindability of the slag, but led to a deterioration in the soundness and cementitious characteristics of the slag powders. These results provide guidance for optimizing the chemical composition of steel slag during steelmaking to improve its use in cementing materials and thereby alleviate slag pollution and carbon dioxide emissions caused by cement production. [ABSTRACT FROM AUTHOR]